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-rw-r--r--lib/sasl/doc/src/appup.xml3
-rw-r--r--lib/sasl/doc/src/error_logging.xml5
-rw-r--r--lib/stdlib/doc/src/Makefile3
-rw-r--r--lib/stdlib/doc/src/gen_fsm.xml14
-rw-r--r--lib/stdlib/doc/src/gen_server.xml1
-rw-r--r--lib/stdlib/doc/src/gen_statem.xml1715
-rw-r--r--lib/stdlib/doc/src/proc_lib.xml6
-rw-r--r--lib/stdlib/doc/src/ref_man.xml3
-rw-r--r--lib/stdlib/doc/src/specs.xml1
-rw-r--r--lib/stdlib/doc/src/supervisor.xml8
-rw-r--r--lib/stdlib/doc/src/sys.xml29
-rw-r--r--lib/stdlib/src/Makefile3
-rw-r--r--lib/stdlib/src/gen.erl119
-rw-r--r--lib/stdlib/src/gen_event.erl9
-rw-r--r--lib/stdlib/src/gen_fsm.erl83
-rw-r--r--lib/stdlib/src/gen_server.erl110
-rw-r--r--lib/stdlib/src/gen_statem.erl1257
-rw-r--r--lib/stdlib/src/proc_lib.erl14
-rw-r--r--lib/stdlib/src/stdlib.app.src1
-rw-r--r--lib/stdlib/test/Makefile1
-rw-r--r--lib/stdlib/test/error_logger_forwarder.erl6
-rw-r--r--lib/stdlib/test/gen_statem_SUITE.erl1578
-rw-r--r--lib/tools/doc/src/erlang_mode.xml1
-rw-r--r--lib/tools/emacs/erlang-skels.el118
-rw-r--r--system/doc/definitions/term.defs1
-rw-r--r--system/doc/design_principles/Makefile15
-rw-r--r--system/doc/design_principles/appup_cookbook.xml3
-rw-r--r--system/doc/design_principles/code_lock.diabin0 -> 2955 bytes
-rw-r--r--system/doc/design_principles/code_lock.pngbin0 -> 58823 bytes
-rw-r--r--system/doc/design_principles/code_lock_2.diabin0 -> 2646 bytes
-rw-r--r--system/doc/design_principles/code_lock_2.pngbin0 -> 51848 bytes
-rw-r--r--system/doc/design_principles/des_princ.xml4
-rw-r--r--system/doc/design_principles/fsm.xml10
-rw-r--r--system/doc/design_principles/part.xml1
-rw-r--r--system/doc/design_principles/release_handling.xml2
-rw-r--r--system/doc/design_principles/statem.xml1451
-rw-r--r--system/doc/design_principles/sup_princ.xml6
-rw-r--r--system/doc/design_principles/xmlfiles.mk1
-rw-r--r--system/doc/reference_manual/modules.xml3
39 files changed, 6341 insertions, 244 deletions
diff --git a/lib/sasl/doc/src/appup.xml b/lib/sasl/doc/src/appup.xml
index a57068492c..6fbdcb9f5b 100644
--- a/lib/sasl/doc/src/appup.xml
+++ b/lib/sasl/doc/src/appup.xml
@@ -137,7 +137,8 @@
code change. If it is set to <c>{advanced,Extra}</c>, implemented
processes using
<seealso marker="stdlib:gen_server"><c>gen_server</c></seealso>,
- <seealso marker="stdlib:gen_fsm"><c>gen_fsm</c></seealso>, or
+ <seealso marker="stdlib:gen_fsm"><c>gen_fsm</c></seealso>,
+ <seealso marker="stdlib:gen_statem"><c>gen_statem</c></seealso>, or
<seealso marker="stdlib:gen_event"><c>gen_event</c></seealso>
transform their internal state by calling the callback function
<c>code_change</c>. Special processes call the callback
diff --git a/lib/sasl/doc/src/error_logging.xml b/lib/sasl/doc/src/error_logging.xml
index 86d0c811e9..8464a41ff9 100644
--- a/lib/sasl/doc/src/error_logging.xml
+++ b/lib/sasl/doc/src/error_logging.xml
@@ -90,8 +90,9 @@
a process terminates with an unexpected reason, which is any reason
other than <c>normal</c>, <c>shutdown</c>, or <c>{shutdown,Term}</c>.
Processes using behaviors
- <seealso marker="stdlib:gen_server"><c>gen_server</c></seealso> or
- <seealso marker="stdlib:gen_fsm"><c>gen_fsm</c></seealso>
+ <seealso marker="stdlib:gen_server"><c>gen_server</c></seealso>,
+ <seealso marker="stdlib:gen_fsm"><c>gen_fsm</c></seealso> or
+ <seealso marker="stdlib:gen_statem"><c>gen_statem</c></seealso>
are examples of such processes. A crash report contains the following items:</p>
<taglist>
<tag><c>Crasher</c></tag>
diff --git a/lib/stdlib/doc/src/Makefile b/lib/stdlib/doc/src/Makefile
index 196c86748f..26602764a6 100644
--- a/lib/stdlib/doc/src/Makefile
+++ b/lib/stdlib/doc/src/Makefile
@@ -1,7 +1,7 @@
#
# %CopyrightBegin%
#
-# Copyright Ericsson AB 1997-2015. All Rights Reserved.
+# Copyright Ericsson AB 1997-2016. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
@@ -68,6 +68,7 @@ XML_REF3_FILES = \
gen_event.xml \
gen_fsm.xml \
gen_server.xml \
+ gen_statem.xml \
io.xml \
io_lib.xml \
lib.xml \
diff --git a/lib/stdlib/doc/src/gen_fsm.xml b/lib/stdlib/doc/src/gen_fsm.xml
index 37e7c6ed17..835e252704 100644
--- a/lib/stdlib/doc/src/gen_fsm.xml
+++ b/lib/stdlib/doc/src/gen_fsm.xml
@@ -31,12 +31,23 @@
<module>gen_fsm</module>
<modulesummary>Generic Finite State Machine Behaviour</modulesummary>
<description>
+ <note>
+ <p>
+ There is a new behaviour
+ <seealso marker="gen_statem"><c>gen_statem</c></seealso>
+ that is intended to replace <c>gen_fsm</c> for new code.
+ It has the same features and add some really useful.
+ This module will not be removed for the foreseeable future
+ to keep old state machine implementations running.
+ </p>
+ </note>
<p>A behaviour module for implementing a finite state machine.
A generic finite state machine process (gen_fsm) implemented
using this module will have a standard set of interface functions
and include functionality for tracing and error reporting. It will
also fit into an OTP supervision tree. Refer to
- <seealso marker="doc/design_principles:fsm">OTP Design Principles</seealso> for more information.</p>
+ <seealso marker="doc/design_principles:fsm">OTP Design Principles</seealso> for more information.
+ </p>
<p>A gen_fsm assumes all specific parts to be located in a callback
module exporting a pre-defined set of functions. The relationship
between the behaviour functions and the callback functions can be
@@ -848,6 +859,7 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4
<title>SEE ALSO</title>
<p><seealso marker="gen_event">gen_event(3)</seealso>,
<seealso marker="gen_server">gen_server(3)</seealso>,
+ <seealso marker="gen_statem">gen_statem(3)</seealso>,
<seealso marker="supervisor">supervisor(3)</seealso>,
<seealso marker="proc_lib">proc_lib(3)</seealso>,
<seealso marker="sys">sys(3)</seealso></p>
diff --git a/lib/stdlib/doc/src/gen_server.xml b/lib/stdlib/doc/src/gen_server.xml
index 02da11250a..10dc978afc 100644
--- a/lib/stdlib/doc/src/gen_server.xml
+++ b/lib/stdlib/doc/src/gen_server.xml
@@ -715,6 +715,7 @@ gen_server:abcast -----> Module:handle_cast/2
<title>SEE ALSO</title>
<p><seealso marker="gen_event">gen_event(3)</seealso>,
<seealso marker="gen_fsm">gen_fsm(3)</seealso>,
+ <seealso marker="gen_statem">gen_statem(3)</seealso>,
<seealso marker="supervisor">supervisor(3)</seealso>,
<seealso marker="proc_lib">proc_lib(3)</seealso>,
<seealso marker="sys">sys(3)</seealso></p>
diff --git a/lib/stdlib/doc/src/gen_statem.xml b/lib/stdlib/doc/src/gen_statem.xml
new file mode 100644
index 0000000000..91332fbdde
--- /dev/null
+++ b/lib/stdlib/doc/src/gen_statem.xml
@@ -0,0 +1,1715 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+ <header>
+ <copyright>
+ <year>2016</year>
+ <holder>Ericsson AB. All Rights Reserved.</holder>
+ </copyright>
+ <legalnotice>
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+ </legalnotice>
+
+ <title>gen_statem</title>
+ <prepared></prepared>
+ <docno></docno>
+ <date></date>
+ <rev></rev>
+ </header>
+ <module>gen_statem</module>
+ <modulesummary>Generic State Machine Behaviour</modulesummary>
+ <description>
+ <p>
+ A behaviour module for implementing a state machine. Two
+ <seealso marker="#type-callback_mode"><em>callback modes</em></seealso>
+ are supported. One for finite state machines
+ (<seealso marker="gen_fsm"><c>gen_fsm</c></seealso> like)
+ that requires the state to be an atom and uses that state as
+ the name of the current callback function,
+ and one without restriction on the state data type
+ that uses one callback function for all states.
+ </p>
+ <p>
+ This is a new behaviour in OTP-19.0.
+ It has been thoroughly reviewed, is stable enough
+ to be used by at least two heavy OTP applications, and is here to stay.
+ But depending on user feedback, we do not expect
+ but might find it necessary to make minor
+ not backwards compatible changes into OTP-20.0,
+ so its state can be designated as "not quite experimental"...
+ </p>
+ <p>
+ The <c>gen_statem</c> behaviour is intended to replace
+ <seealso marker="gen_fsm"><c>gen_fsm</c></seealso> for new code.
+ It has the same features and add some really useful:
+ </p>
+ <list type="bulleted">
+ <item>State code is gathered</item>
+ <item>The state can be any term</item>
+ <item>Events can be postponed</item>
+ <item>Events can be self generated</item>
+ <item>A reply can be sent from a later state</item>
+ <item>There can be multiple sys traceable replies</item>
+ </list>
+ <p>
+ The callback model(s) for <c>gen_statem</c> differs from
+ the one for <seealso marker="gen_fsm"><c>gen_fsm</c></seealso>,
+ but it is still fairly easy to rewrite
+ from <c>gen_fsm</c> to <c>gen_statem</c>.
+ </p>
+ <p>
+ A generic state machine process (<c>gen_statem</c>) implemented
+ using this module will have a standard set of interface functions
+ and include functionality for tracing and error reporting.
+ It will also fit into an OTP supervision tree. Refer to
+ <seealso marker="doc/design_principles:statem">
+ OTP Design Principles
+ </seealso>
+ for more information.
+ </p>
+ <p>
+ A <c>gen_statem</c> assumes all specific parts to be located in a
+ callback module exporting a pre-defined set of functions.
+ The relationship between the behaviour functions and the callback
+ functions can be illustrated as follows:</p>
+ <pre>
+gen_statem module Callback module
+----------------- ---------------
+gen_statem:start
+gen_statem:start_link -----> Module:init/1
+
+gen_statem:stop -----> Module:terminate/3
+
+gen_statem:call
+gen_statem:cast
+erlang:send
+erlang:'!' -----> Module:StateName/3
+ Module:handle_event/4
+
+- -----> Module:terminate/3
+
+- -----> Module:code_change/4</pre>
+ <p>
+ Events are of different
+ <seealso marker="#type-event_type">types</seealso>
+ so the callback functions can know the origin of an event
+ and how to respond.
+ </p>
+ <p>
+ If a callback function fails or returns a bad value,
+ the <c>gen_statem</c> will terminate. An exception of class
+ <seealso marker="erts:erlang#throw/1"><c>throw</c></seealso>,
+ however, is not regarded as an error but as a valid return.
+ </p>
+ <marker id="state_function" />
+ <p>
+ The "<em>state function</em>" for a specific
+ <seealso marker="#type-state">state</seealso>
+ in a <c>gen_statem</c> is the callback function that is called
+ for all events in this state, and is selected depending on which
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
+ that the implementation specifies when the the server starts.
+ </p>
+ <p>
+ When the
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
+ is <c>state_functions</c>, the state has to be an atom and
+ is used as the state function name. See
+ <seealso marker="#Module:StateName/3">
+ <c>Module:StateName/3</c>
+ </seealso>.
+ This gathers all code for a specific state
+ in one function and hence dispatches on state first.
+ Note that in this mode the fact that there is
+ a mandatory callback function
+ <seealso marker="#Module:terminate/3">
+ <c>Module:terminate/3</c>
+ </seealso> makes the state name <c>terminate</c> unusable.
+ </p>
+ <p>
+ When the
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
+ is <c>handle_event_function</c> the state can be any term
+ and the state function name is
+ <seealso marker="#Module:handle_event/4">
+ <c>Module:handle_event/4</c>
+ </seealso>.
+ This makes it easy to dispatch on state or on event as you desire.
+ Be careful about which events you handle in which
+ states so you do not accidentally postpone one event
+ forever creating an infinite busy loop.
+ </p>
+ <p>
+ The <c>gen_statem</c> enqueues incoming events in order of arrival
+ and presents these to the
+ <seealso marker="#state_function">state function</seealso>
+ in that order. The state function can postpone an event
+ so it is not retried in the current state.
+ After a state change the queue restarts with the postponed events.
+ </p>
+ <p>
+ The <c>gen_statem</c> event queue model is sufficient
+ to emulate the normal process message queue with selective receive.
+ Postponing an event corresponds to not matching it
+ in a receive statement and changing states corresponds
+ to entering a new receive statement.
+ </p>
+ <p>
+ The <seealso marker="#state_function">state function</seealso>
+ can insert events using the
+ <seealso marker="#type-action">
+ <c>action()</c> <c>next_event</c>
+ </seealso>
+ and such an event is inserted as the next to present
+ to the state function. That is: as if it is
+ the oldest incoming event. There is a dedicated
+ <seealso marker="#type-event_type">
+ <c>event_type()</c>
+ </seealso>
+ <c>internal</c> that can be used for such events making them impossible
+ to mistake for external events.
+ </p>
+ <p>
+ Inserting an event replaces the trick of calling your own
+ state handling functions that you often would have to
+ resort to in for example <seealso marker="gen_fsm"><c>gen_fsm</c></seealso>
+ to force processing an inserted event before others.
+ A warning, though: if you in <c>gen_statem</c> for example
+ postpone an event in one state and then call some other state function of yours,
+ you have not changed states and hence the postponed event will not be retried,
+ which is logical but might be confusing.
+ </p>
+ <p>
+ See the type
+ <seealso marker="#type-transition_option">
+ <c>transition_option()</c>
+ </seealso>
+ for the details of a state transition.
+ </p>
+ <p>
+ A <c>gen_statem</c> handles system messages as documented in
+ <seealso marker="sys"><c>sys</c></seealso>.
+ The <c>sys</c>module can be used for debugging a <c>gen_statem</c>.
+ </p>
+ <p>
+ Note that a <c>gen_statem</c> does not trap exit signals
+ automatically, this must be explicitly initiated in
+ the callback module (by calling
+ <seealso marker="erts:erlang#process_flag/2">
+ <c>process_flag(trap_exit, true)</c></seealso>.
+ </p>
+ <p>
+ Unless otherwise stated, all functions in this module fail if
+ the specified <c>gen_statem</c> does not exist or
+ if bad arguments are given.
+ </p>
+ <p>
+ The <c>gen_statem</c> process can go into hibernation (see
+ <seealso marker="erts:erlang#hibernate/3">
+ <c>erlang:hibernate/3</c>
+ </seealso>) if a
+ <seealso marker="#state_function">state function</seealso> or
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ specifies <c>hibernate</c> in the returned
+ <seealso marker="#type-action"><c>Actions</c></seealso>
+ list. This might be useful if the server is expected to be idle
+ for a long time. However use this feature with care
+ since hibernation implies at least two garbage collections
+ (when hibernating and shortly after waking up) and that is not
+ something you would want to do between each event on a busy server.
+ </p>
+ </description>
+
+ <section>
+ <title>EXAMPLE</title>
+ <p>
+ This example shows a simple pushbutton model
+ for a toggling pushbutton implemented with
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
+ <c>state_functions</c>.
+ You can push the button and it replies if it went on or off,
+ and you can ask for a count of how many times it has been
+ pushed to on.
+ </p>
+ <p>This is the complete callback module file <c>pushbutton.erl</c>:</p>
+ <code type="erl">
+-module(pushbutton).
+-behaviour(gen_statem).
+
+-export([start/0,push/0,get_count/0,stop/0]).
+-export([terminate/3,code_change/4,init/1]).
+-export([on/3,off/3]).
+
+name() -> pushbutton_statem. % The registered server name
+callback_mode() -> state_functions.
+
+%% API. This example uses a registered name name()
+%% and does not link to the caller.
+start() ->
+ gen_statem:start({local,name()}, ?MODULE, [], []).
+push() ->
+ gen_statem:call(name(), push).
+get_count() ->
+ gen_statem:call(name(), get_count).
+stop() ->
+ gen_statem:stop(name()).
+
+%% Mandatory callback functions
+terminate(_Reason, _State, _Data) ->
+ void.
+code_change(_Vsn, State, Data, _Extra) ->
+ {callback_mode(),State,Data}.
+init([]) ->
+ %% Set the callback mode and initial state + data.
+ %% Data is used only as a counter.
+ State = off, Data = 0,
+ {callback_mode(),State,Data}.
+
+
+%%% State functions
+
+off({call,From}, push, Data) ->
+ %% Go to 'on', increment count and reply
+ %% that the resulting status is 'on'
+ {next_state,on,Data+1,[{reply,From,on}]};
+off(EventType, EventContent, Data) ->
+ handle_event(EventType, EventContent, Data).
+
+on({call,From}, push, Data) ->
+ %% Go to 'off' and reply that the resulting status is 'off'
+ {next_state,off,Data,[{reply,From,off}]};
+on(EventType, EventContent, Data) ->
+ handle_event(EventType, EventContent, Data).
+
+%% Handle events common to all states
+handle_event({call,From}, get_count, Data) ->
+ %% Reply with the current count
+ {keep_state,Data,[{reply,From,Data}]};
+handle_event(_, _, Data) ->
+ %% Ignore all other events
+ {keep_state,Data}.
+ </code>
+ <p>And this is a shell session when running it:</p>
+ <pre>
+1> pushbutton:start().
+{ok,&lt;0.36.0>}
+2> pushbutton:get_count().
+0
+3> pushbutton:push().
+on
+4> pushbutton:get_count().
+1
+5> pushbutton:push().
+off
+6> pushbutton:get_count().
+1
+7> pushbutton:stop().
+ok
+8> pushbutton:push().
+** exception exit: {noproc,{gen_statem,call,[pushbutton_statem,push,infinity]}}
+ in function gen:do_for_proc/2 (gen.erl, line 261)
+ in call from gen_statem:call/3 (gen_statem.erl, line 386)
+ </pre>
+
+ <p>
+ And just to compare styles here is the same example using
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
+ <c>state_functions</c>, or rather here is code to replace
+ from the <c>init/1</c> function of the <c>pushbutton.erl</c>
+ example file above:
+ </p>
+ <code type="erl">
+init([]) ->
+ %% Set the callback mode and initial state + data.
+ %% Data is used only as a counter.
+ State = off, Data = 0,
+ {handle_event_function,State,Data}.
+
+
+%%% Event handling
+
+handle_event({call,From}, push, off, Data) ->
+ %% Go to 'on', increment count and reply
+ %% that the resulting status is 'on'
+ {next_state,on,Data+1,[{reply,From,on}]};
+handle_event({call,From}, push, on, Data) ->
+ %% Go to 'off' and reply that the resulting status is 'off'
+ {next_state,off,Data,[{reply,From,off}]};
+%%
+%% Event handling common to all states
+handle_event({call,From}, get_count, State, Data) ->
+ %% Reply with the current count
+ {next_state,State,Data,[{reply,From,Data}]};
+handle_event(_, _, State, Data) ->
+ %% Ignore all other events
+ {next_state,State,Data}.
+ </code>
+ </section>
+
+ <datatypes>
+ <datatype>
+ <name name="server_name" />
+ <desc>
+ <p>
+ Name specification to use when starting
+ a <c>gen_statem</c> server. See
+ <seealso marker="#start_link/3">
+ <c>start_link/3</c>
+ </seealso>
+ and
+ <seealso marker="#type-server_ref">
+ <c>server_ref()</c>
+ </seealso> below.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="server_ref" />
+ <desc>
+ <p>
+ Server specification to use when addressing
+ a <c>gen_statem</c> server.
+ See <seealso marker="#call/2"><c>call/2</c></seealso> and
+ <seealso marker="#type-server_name">
+ <c>server_name()</c>
+ </seealso>
+ above.
+ </p>
+ <p>It can be:</p>
+ <taglist>
+ <tag><c>pid()</c><br />
+ <c>LocalName</c></tag>
+ <item>The <c>gen_statem</c> is locally registered.</item>
+ <tag><c>Name, Node</c></tag>
+ <item>
+ The <c>gen_statem</c> is locally registered
+ on another node.
+ </item>
+ <tag><c>GlobalName</c></tag>
+ <item>
+ The <c>gen_statem</c> is globally registered
+ in <seealso marker="kernel:global"><c>global</c></seealso>.
+ </item>
+ <tag><c>RegMod, ViaName</c></tag>
+ <item>
+ The <c>gen_statem</c> is registered through
+ an alternative process registry.
+ The registry callback module <c>RegMod</c>
+ should export the functions
+ <c>register_name/2</c>, <c>unregister_name/1</c>,
+ <c>whereis_name/1</c> and <c>send/2</c>,
+ which should behave like the corresponding functions
+ in <seealso marker="kernel:global"><c>global</c></seealso>.
+ Thus, <c>{via,global,GlobalName}</c> is the same as
+ <c>{global,GlobalName}</c>.
+ </item>
+ </taglist>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="debug_opt" />
+ <desc>
+ <p>
+ Debug option that can be used when starting
+ a <c>gen_statem</c> server through for example
+ <seealso marker="#enter_loop/5"><c>enter_loop/5</c></seealso>.
+ </p>
+ <p>
+ For every entry in <c><anno>Dbgs</anno></c>
+ the corresponding function in
+ <seealso marker="sys"><c>sys</c></seealso> will be called.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="start_opt" />
+ <desc>
+ <p>
+ Options that can be used when starting
+ a <c>gen_statem</c> server through for example
+ <seealso marker="#start_link/3"><c>start_link/3</c></seealso>.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="start_ret" />
+ <desc>
+ <p>
+ Return value from the start functions for_example
+ <seealso marker="#start_link/3"><c>start_link/3</c></seealso>.
+ </p>
+ </desc>
+ </datatype>
+
+ <datatype>
+ <name name="from" />
+ <desc>
+ <p>
+ Destination to use when replying through for example the
+ <seealso marker="#type-action">
+ <c>action()</c>
+ </seealso>
+ <c>{reply,From,Reply}</c>
+ to a process that has called the <c>gen_statem</c> server using
+ <seealso marker="#call/2"><c>call/2</c></seealso>.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="state" />
+ <desc>
+ <p>
+ After a state change (<c>NextState =/= State</c>)
+ all postponed events are retried.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="state_name" />
+ <desc>
+ <p>
+ If the
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
+ is <c>state_functions</c>,
+ the state has to be of this type.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="data" />
+ <desc>
+ <p>
+ A term in which the state machine implementation
+ should store any server data it needs. The difference between
+ this and the <seealso marker="#type-state"><c>state()</c></seealso>
+ itself is that a change in this data does not cause
+ postponed events to be retried. Hence if a change
+ in this data would change the set of events that
+ are handled than that data item should be made
+ a part of the state.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="event_type" />
+ <desc>
+ <p>
+ External events are of 3 different type:
+ <c>{call,<anno>From</anno>}</c>, <c>cast</c> or <c>info</c>.
+ <seealso marker="#call/2">Calls</seealso>
+ (synchronous) and
+ <seealso marker="#cast/2">casts</seealso>
+ originate from the corresponding API functions.
+ For calls the event contain whom to reply to.
+ Type <c>info</c> originates from regular process messages sent
+ to the <c>gen_statem</c>. It is also possible for the state machine
+ implementation to generate events of types
+ <c>timeout</c> and <c>internal</c> to itself.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="callback_mode" />
+ <desc>
+ <p>
+ The <em>callback mode</em> is selected when starting the
+ <c>gen_statem</c> using the return value from
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ or when calling
+ <seealso marker="#enter_loop/5"><c>enter_loop/5-7</c></seealso>,
+ and with the return value from
+ <seealso marker="#Module:code_change/4">
+ <c>Module:code_change/4</c>.
+ </seealso>
+ </p>
+ <taglist>
+ <tag><c>state_functions</c></tag>
+ <item>
+ The state has to be of type
+ <seealso marker="#type-state_name"><c>state_name()</c></seealso>
+ and one callback function per state that is
+ <seealso marker="#Module:StateName/3">
+ <c>Module:StateName/3</c>
+ </seealso>
+ is used.
+ </item>
+ <tag><c>handle_event_function</c></tag>
+ <item>
+ The state can be any term and the callback function
+ <seealso marker="#Module:handle_event/4">
+ <c>Module:handle_event/4</c>
+ </seealso>
+ is used for all states.
+ </item>
+ </taglist>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="transition_option" />
+ <desc>
+ <p>
+ Transition options may be set by
+ <seealso marker="#type-action">actions</seealso>
+ and they modify some details below in how
+ the state transition is done:
+ </p>
+ <list type="ordered">
+ <item>
+ All
+ <seealso marker="#type-action">actions</seealso>
+ are processed in order of appearance.
+ </item>
+ <item>
+ If
+ <seealso marker="#type-postpone">
+ <c>postpone()</c>
+ </seealso>
+ is <c>true</c>
+ the current event is postponed.
+ </item>
+ <item>
+ If the state changes the queue of incoming events
+ is reset to start with the oldest postponed.
+ </item>
+ <item>
+ All events stored with
+ <seealso marker="#type-action">
+ <c>action()</c>
+ </seealso>
+ <c>next_event</c>
+ are inserted in the queue to be processed before
+ all other events.
+ </item>
+ <item>
+ If an
+ <seealso marker="#type-event_timeout">
+ <c>event_timeout()</c>
+ </seealso>
+ is set through
+ <seealso marker="#type-action">
+ <c>action()</c>
+ </seealso>
+ <c>timeout</c>
+ an event timer may be started or a timeout zero event
+ may be enqueued.
+ </item>
+ <item>
+ The (possibly new)
+ <seealso marker="#state_function">state function</seealso>
+ is called with the oldest enqueued event if there is any,
+ otherwise the <c>gen_statem</c> goes into <c>receive</c>
+ or hibernation
+ (if
+ <seealso marker="#type-hibernate">
+ <c>hibernate()</c>
+ </seealso>
+ is <c>true</c>)
+ to wait for the next message. In hibernation the next
+ non-system event awakens the <c>gen_statem</c>, or rather
+ the next incoming message awakens the <c>gen_statem</c>
+ but if it is a system event it goes back into hibernation.
+ </item>
+ </list>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="postpone" />
+ <desc>
+ <p>
+ If <c>true</c> postpone the current event and retry
+ it when the state changes
+ (<c>NextState =/= State</c>).
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="hibernate" />
+ <desc>
+ <p>
+ If <c>true</c> hibernate the <c>gen_statem</c>
+ by calling
+ <seealso marker="proc_lib#hibernate/3">
+ <c>proc_lib:hibernate/3</c>
+ </seealso>
+ before going into <c>receive</c>
+ to wait for a new external event.
+ If there are enqueued events the <c>hibernate</c>
+ is ignored as if an event just arrived and awakened
+ the <c>gen_statem</c>.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="event_timeout" />
+ <desc>
+ <p>
+ Generate an event of
+ <seealso marker="#type-event_type"><c>event_type()</c></seealso>
+ <c>timeout</c>
+ after this time (in milliseconds) unless some other
+ event arrives in which case this timeout is cancelled.
+ Note that a retried or inserted event
+ counts just like a new in this respect.
+ </p>
+ <p>
+ If the value is <c>infinity</c> no timer is started since
+ it will never trigger anyway.
+ </p>
+ <p>
+ If the value is <c>0</c> the timeout event is immediately enqueued
+ unless there already are enqueued events since then the
+ timeout is immediately cancelled.
+ This is a feature ensuring that a timeout <c>0</c> event
+ will be processed before any not yet received external event.
+ </p>
+ <p>
+ Note that it is not possible nor needed to cancel this timeout
+ since it is cancelled automatically by any other event.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="action" />
+ <desc>
+ <p>
+ These state transition actions may be invoked by
+ returning them from the
+ <seealso marker="#state_function">state function</seealso>,
+ from <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ or by giving them to
+ <seealso marker="#enter_loop/6"><c>enter_loop/6,7</c></seealso>.
+ </p>
+ <p>
+ Actions are executed in the containing list order.
+ </p>
+ <p>
+ Actions that set
+ <seealso marker="#type-transition_option">
+ transition options
+ </seealso>
+ overrides any previous of the same type,
+ so the last in the containing list wins.
+ For example the last
+ <seealso marker="#type-event_timeout">
+ <c>event_timeout()</c>
+ </seealso>
+ overrides any other <c>event_timeout()</c> in the list.
+ </p>
+ <taglist>
+ <tag><c>postpone</c></tag>
+ <item>
+ Set the
+ <seealso marker="#type-transition_option">
+ <c>transition_option()</c>
+ </seealso>
+ <seealso marker="#type-postpone">
+ <c>postpone()</c>
+ </seealso>
+ for this state transition.
+ This action is ignored when returned from
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ or given to
+ <seealso marker="#enter_loop/5"><c>enter_loop/5,6</c></seealso>
+ since there is no event to postpone in those cases.
+ </item>
+ <tag><c>hibernate</c></tag>
+ <item>
+ Set the
+ <seealso marker="#type-transition_option">
+ <c>transition_option()</c>
+ </seealso>
+ <seealso marker="#type-hibernate">
+ <c>hibernate()</c>
+ </seealso>
+ for this state transition.
+ </item>
+ <tag><c>Timeout</c></tag>
+ <item>
+ Short for <c>{timeout,Timeout,Timeout}</c> that is
+ the timeout message is the timeout time.
+ This form exists to make the
+ <seealso marker="#state_function">state function</seealso>
+ return value <c>{next_state,NextState,NewData,Timeout}</c>
+ allowed like for
+ <seealso marker="gen_fsm#Module:StateName/2">
+ <c>gen_fsm Module:StateName/2</c>.
+ </seealso>
+ </item>
+ <tag><c>timeout</c></tag>
+ <item>
+ Set the
+ <seealso marker="#type-transition_option">
+ <c>transition_option()</c>
+ </seealso>
+ <seealso marker="#type-event_timeout">
+ <c>event_timeout()</c>
+ </seealso>
+ to <c><anno>Time</anno></c> with <c><anno>EventContent</anno></c>.
+ </item>
+ <tag><c>reply_action()</c></tag>
+ <item>Reply to a caller.</item>
+ <tag><c>next_event</c></tag>
+ <item>
+ Store the given <c><anno>EventType</anno></c>
+ and <c><anno>EventContent</anno></c> for insertion after all
+ actions have been executed.
+ </item>
+ <item>
+ <p>
+ The stored events are inserted in the queue as the next to process
+ before any already queued events. The order of these stored events
+ is preserved so the first <c>next_event</c> in the containing list
+ will become the first to process.
+ </p>
+ </item>
+ <item>
+ <p>
+ An event of type
+ <seealso marker="#type-event_type">
+ <c>internal</c>
+ </seealso>
+ should be used when you want to reliably distinguish
+ an event inserted this way from any external event.
+ </p>
+ </item>
+ </taglist>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="reply_action" />
+ <desc>
+ <p>
+ Reply to a caller waiting for a reply in
+ <seealso marker="#call/2"><c>call/2</c></seealso>.
+ <c><anno>From</anno></c> must be the term from the
+ <seealso marker="#type-event_type">
+ <c>{call,<anno>From</anno>}</c>
+ </seealso>
+ argument to the
+ <seealso marker="#state_function">state function</seealso>.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="state_function_result" />
+ <desc>
+ <taglist>
+ <tag><c>next_state</c></tag>
+ <item>
+ The <c>gen_statem</c> will do a state transition to
+ <c><anno>NextStateName</anno></c>
+ (which may be the same as the current state),
+ set <c><anno>NewData</anno></c>
+ and execute all <c><anno>Actions</anno></c>
+ </item>
+ </taglist>
+ <p>
+ All these terms are tuples or atoms and this property
+ will hold in any future version of <c>gen_statem</c>,
+ just in case you need such a promise.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="handle_event_result" />
+ <desc>
+ <taglist>
+ <tag><c>next_state</c></tag>
+ <item>
+ The <c>gen_statem</c> will do a state transition to
+ <c><anno>NextState</anno></c>
+ (which may be the same as the current state),
+ set <c><anno>NewData</anno></c>
+ and execute all <c><anno>Actions</anno></c>
+ </item>
+ </taglist>
+ <p>
+ All these terms are tuples or atoms and this property
+ will hold in any future version of <c>gen_statem</c>,
+ just in case you need such a promise.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="common_state_callback_result" />
+ <desc>
+ <taglist>
+ <tag><c>stop</c></tag>
+ <item>
+ Terminate the <c>gen_statem</c> by calling
+ <seealso marker="#Module:terminate/3">
+ <c>Module:terminate/3</c>
+ </seealso>
+ with <c>Reason</c> and
+ <c><anno>NewData</anno></c>, if given.
+ </item>
+ <tag><c>stop_and_reply</c></tag>
+ <item>
+ Send all <c><anno>Replies</anno></c>
+ then terminate the <c>gen_statem</c> by calling
+ <seealso marker="#Module:terminate/3">
+ <c>Module:terminate/3</c>
+ </seealso>
+ with <c>Reason</c> and
+ <c><anno>NewData</anno></c>, if given.
+ </item>
+ <tag><c>keep_state</c></tag>
+ <item>
+ The <c>gen_statem</c> will keep the current state, or
+ do a state transition to the current state if you like,
+ set <c><anno>NewData</anno></c>
+ and execute all <c><anno>Actions</anno></c>.
+ This is the same as
+ <c>{next_state,CurrentState,<anno>NewData</anno>,<anno>Actions</anno>}</c>.
+ </item>
+ <tag><c>keep_state_and_data</c></tag>
+ <item>
+ The <c>gen_statem</c> will keep the current state or
+ do a state transition to the current state if you like,
+ keep the current server data,
+ and execute all <c><anno>Actions</anno></c>.
+ This is the same as
+ <c>{next_state,CurrentState,CurrentData,<anno>Actions</anno>}</c>.
+ </item>
+ </taglist>
+ <p>
+ All these terms are tuples or atoms and this property
+ will hold in any future version of <c>gen_statem</c>,
+ just in case you need such a promise.
+ </p>
+ </desc>
+ </datatype>
+ </datatypes>
+
+ <funcs>
+
+ <func>
+ <name name="start_link" arity="3" />
+ <name name="start_link" arity="4" />
+ <fsummary>Create a linked <c>gen_statem</c> process</fsummary>
+ <desc>
+ <p>
+ Creates a <c>gen_statem</c> process according
+ to OTP design principles
+ (using
+ <seealso marker="proc_lib"><c>proc_lib</c></seealso>
+ primitives)
+ that is linked to the calling process.
+ This is essential when the <c>gen_statem</c> shall be part of
+ a supervision tree so it gets linked to its supervisor.
+ </p>
+ <p>
+ The <c>gen_statem</c> process calls
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ to initialize the server. To ensure a synchronized start-up
+ procedure, <c>start_link/3,4</c> does not return until
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ has returned.
+ </p>
+ <p>
+ <c><anno>ServerName</anno></c> specifies the
+ <seealso marker="#type-server_name">
+ <c>server_name()</c>
+ </seealso>
+ to register for the <c>gen_statem</c>.
+ If the <c>gen_statem</c> is started with <c>start_link/3</c>
+ no <c><anno>ServerName</anno></c> is provided and
+ the <c>gen_statem</c> is not registered.
+ </p>
+ <p><c><anno>Module</anno></c> is the name of the callback module.</p>
+ <p>
+ <c><anno>Args</anno></c> is an arbitrary term which is passed as
+ the argument to
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>.
+ </p>
+ <p>
+ If the option <c>{timeout,Time}</c> is present in
+ <c><anno>Opts</anno></c>, the <c>gen_statem</c>
+ is allowed to spend <c>Time</c> milliseconds initializing
+ or it will be terminated and the start function will return
+ <seealso marker="#type-start_ret"><c>{error,timeout}</c></seealso>.
+ </p>
+ <p>
+ If the option
+ <seealso marker="#type-debug_opt"><c>{debug,Dbgs}</c></seealso>
+ is present in <c><anno>Opts</anno></c>, debugging through
+ <seealso marker="sys"><c>sys</c></seealso> is activated.
+ </p>
+ <p>
+ If the option <c>{spawn_opt,SpawnOpts}</c> is present in
+ <c><anno>Opts</anno></c>, <c>SpawnOpts</c> will be passed
+ as option list to
+ <seealso marker="erts:erlang#spawn_opt/2"><c>spawn_opt/2</c></seealso>
+ which is used to spawn the <c>gen_statem</c> process.
+ </p>
+ <note>
+ <p>
+ Using the spawn option <c>monitor</c> is currently not
+ allowed, but will cause this function to fail with reason
+ <c>badarg</c>.
+ </p>
+ </note>
+ <p>
+ If the <c>gen_statem</c> is successfully created
+ and initialized this function returns
+ <seealso marker="#type-start_ret">
+ <c>{ok,Pid}</c>,
+ </seealso>
+ where <c>Pid</c> is the <c>pid()</c>
+ of the <c>gen_statem</c>.
+ If there already exists a process with the specified
+ <c><anno>ServerName</anno></c> this function returns
+ <seealso marker="#type-start_ret"><c>{error,{already_started,Pid}}</c></seealso>,
+ where <c>Pid</c> is the <c>pid()</c> of that process.
+ </p>
+ <p>
+ If <c>Module:init/1</c> fails with <c>Reason</c>,
+ this function returns
+ <seealso marker="#type-start_ret"><c>{error,Reason}</c></seealso>.
+ If <c>Module:init/1</c> returns
+ <seealso marker="#type-start_ret">
+ <c>{stop,Reason}</c>
+ </seealso>
+ or
+ <seealso marker="#type-start_ret"><c>ignore</c></seealso>,
+ the process is terminated and this function
+ returns
+ <seealso marker="#type-start_ret">
+ <c>{error,Reason}</c>
+ </seealso>
+ or
+ <seealso marker="#type-start_ret"><c>ignore</c></seealso>,
+ respectively.
+ </p>
+ </desc>
+ </func>
+
+
+ <func>
+ <name name="start" arity="3" />
+ <name name="start" arity="4" />
+ <fsummary>Create a stand-alone <c>gen_statem</c> process</fsummary>
+ <desc>
+ <p>
+ Creates a stand-alone <c>gen_statem</c> process according to
+ OTP design principles (using
+ <seealso marker="proc_lib"><c>proc_lib</c></seealso>
+ primitives).
+ Since it does not get linked to the calling process
+ this start function can not be used by a supervisor
+ to start a child.
+ </p>
+ <p>
+ See <seealso marker="#start_link/3"><c>start_link/3,4</c></seealso>
+ for a description of arguments and return values.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="stop" arity="1" />
+ <fsummary>Synchronously stop a generic server</fsummary>
+ <desc>
+ <p>
+ The same as
+ <seealso marker="#stop/3">
+ <c>stop(<anno>ServerRef</anno>, normal, infinity)</c>.
+ </seealso>
+ </p>
+ </desc>
+ </func>
+ <func>
+ <name name="stop" arity="3" />
+ <fsummary>Synchronously stop a generic server</fsummary>
+ <desc>
+ <p>
+ Orders the <c>gen_statem</c>
+ <seealso marker="#type-server_ref">
+ <c><anno>ServerRef</anno></c>
+ </seealso>
+ to exit with the given <c><anno>Reason</anno></c>
+ and waits for it to terminate.
+ The <c>gen_statem</c> will call
+ <seealso marker="#Module:terminate/3">
+ <c>Module:terminate/3</c>
+ </seealso>
+ before exiting.
+ </p>
+ <p>
+ This function returns <c>ok</c> if the server terminates
+ with the expected reason. Any other reason than <c>normal</c>,
+ <c>shutdown</c>, or <c>{shutdown,Term}</c> will cause an
+ error report to be issued through
+ <seealso marker="kernel:error_logger#format/2">
+ <c>error_logger:format/2</c>.
+ </seealso>
+ The default <c><anno>Reason</anno></c> is <c>normal</c>.
+ </p>
+ <p>
+ <c><anno>Timeout</anno></c> is an integer greater than zero
+ which specifies how many milliseconds to wait for the server to
+ terminate, or the atom <c>infinity</c> to wait indefinitely.
+ The default value is <c>infinity</c>.
+ If the server has not terminated within the specified time,
+ a <c>timeout</c> exception is raised.
+ </p>
+ <p>
+ If the process does not exist, a <c>noproc</c> exception
+ is raised.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="call" arity="2" />
+ <name name="call" arity="3" />
+ <fsummary>Make a synchronous call to a <c>gen_statem</c></fsummary>
+ <desc>
+ <p>
+ Makes a synchronous call to the <c>gen_statem</c>
+ <seealso marker="#type-server_ref">
+ <c><anno>ServerRef</anno></c>
+ </seealso>
+ by sending a request
+ and waiting until its reply arrives.
+ The <c>gen_statem</c> will call the
+ <seealso marker="#state_function">state function</seealso> with
+ <seealso marker="#type-event_type"><c>event_type()</c></seealso>
+ <c>{call,From}</c> and event content
+ <c><anno>Request</anno></c>.
+ </p>
+ <p>
+ A <c><anno>Reply</anno></c> is generated when a
+ <seealso marker="#state_function">state function</seealso>
+ returns with
+ <c>{reply,From,<anno>Reply</anno>}</c> as one
+ <seealso marker="#type-action"><c>action()</c></seealso>,
+ and that <c><anno>Reply</anno></c> becomes the return value
+ of this function.
+ </p>
+ <p>
+ <c><anno>Timeout</anno></c> is an integer greater than zero
+ which specifies how many milliseconds to wait for a reply,
+ or the atom <c>infinity</c> to wait indefinitely,
+ which is the default. If no reply is received within
+ the specified time, the function call fails.
+ </p>
+ <note>
+ <p>
+ To avoid getting a late reply in the caller's
+ inbox this function spawns a proxy process that
+ does the call. A late reply gets delivered to the
+ dead proxy process hence gets discarded. This is
+ less efficient than using
+ <c><anno>Timeout</anno> =:= infinity</c>.
+ </p>
+ </note>
+ <p>
+ The call may fail for example if the <c>gen_statem</c> dies
+ before or during this function call.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="cast" arity="2" />
+ <fsummary>Send an asynchronous event to a <c>gen_statem</c></fsummary>
+ <desc>
+ <p>
+ Sends an asynchronous event to the <c>gen_statem</c>
+ <seealso marker="#type-server_ref">
+ <c><anno>ServerRef</anno></c>
+ </seealso>
+ and returns <c>ok</c> immediately,
+ ignoring if the destination node or <c>gen_statem</c>
+ does not exist.
+ The <c>gen_statem</c> will call the
+ <seealso marker="#state_function">state function</seealso> with
+ <seealso marker="#type-event_type"><c>event_type()</c></seealso>
+ <c>cast</c> and event content
+ <c><anno>Msg</anno></c>.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="reply" arity="1" />
+ <name name="reply" arity="2" />
+ <fsummary>Reply to a caller</fsummary>
+ <desc>
+ <p>
+ This function can be used by a <c>gen_statem</c>
+ to explicitly send a reply to a process that waits in
+ <seealso marker="#call/2"><c>call/2</c></seealso>
+ when the reply cannot be defined in
+ the return value of a
+ <seealso marker="#state_function">state function</seealso>.
+ </p>
+ <p>
+ <c><anno>From</anno></c> must be the term from the
+ <seealso marker="#type-event_type">
+ <c>{call,<anno>From</anno>}</c>
+ </seealso>
+ argument to the
+ <seealso marker="#state_function">state function</seealso>.
+ <c><anno>From</anno></c> and <c><anno>Reply</anno></c>
+ can also be specified using a
+ <seealso marker="#type-reply_action">
+ <c>reply_action()</c>
+ </seealso>
+ and multiple replies with a list of them.
+ </p>
+ <note>
+ <p>
+ A reply sent with this function will not be visible
+ in <seealso marker="sys"><c>sys</c></seealso> debug output.
+ </p>
+ </note>
+ </desc>
+ </func>
+
+ <func>
+ <name name="enter_loop" arity="5" />
+ <fsummary>Enter the <c>gen_statem</c> receive loop</fsummary>
+ <desc>
+ <p>
+ The same as
+ <seealso marker="#enter_loop/7"><c>enter_loop/7</c></seealso>
+ except that no
+ <seealso marker="#type-server_name">
+ <c>server_name()</c>
+ </seealso>
+ must have been registered.
+ </p>
+ </desc>
+ </func>
+ <func>
+ <name name="enter_loop" arity="6" />
+ <fsummary>Enter the <c>gen_statem</c> receive loop</fsummary>
+ <desc>
+ <p>
+ If <c><anno>Server_or_Actions</anno></c> is a <c>list()</c>
+ the same as
+ <seealso marker="#enter_loop/7"><c>enter_loop/7</c></seealso>
+ except that no
+ <seealso marker="#type-server_name">
+ <c>server_name()</c>
+ </seealso>
+ must have been registered and
+ <c>Actions = <anno>Server_or_Actions</anno></c>.
+ </p>
+ <p>
+ Otherwise the same as
+ <seealso marker="#enter_loop/7"><c>enter_loop/7</c></seealso>
+ with
+ <c>Server = <anno>Server_or_Actions</anno></c> and
+ <c>Actions = []</c>.
+ </p>
+ </desc>
+ </func>
+ <func>
+ <name name="enter_loop" arity="7" />
+ <fsummary>Enter the <c>gen_statem</c> receive loop</fsummary>
+ <desc>
+ <p>
+ Makes an the calling process become a <c>gen_statem</c>.
+ Does not return, instead the calling process will enter
+ the <c>gen_statem</c> receive loop and become
+ a <c>gen_statem</c> server.
+ The process <em>must</em> have been started
+ using one of the start functions in
+ <seealso marker="proc_lib"><c>proc_lib</c></seealso>.
+ The user is responsible for any initialization of the process,
+ including registering a name for it.
+ </p>
+ <p>
+ This function is useful when a more complex initialization
+ procedure is needed than
+ the <c>gen_statem</c> behaviour provides.
+ </p>
+ <p>
+ <c><anno>Module</anno></c>, <c><anno>Opts</anno></c> and
+ <c><anno>Server</anno></c> have the same meanings
+ as when calling
+ <seealso marker="#start_link/3">
+ <c>gen_statem:start[_link]/3,4</c>.
+ </seealso>
+ However, the
+ <seealso marker="#type-server_name">
+ <c>server_name()</c>
+ </seealso>
+ name must have been registered accordingly
+ <em>before</em> this function is called.</p>
+ <p>
+ <c><anno>CallbackMode</anno></c>, <c><anno>State</anno></c>,
+ <c><anno>Data</anno></c> and <c><anno>Actions</anno></c>
+ have the same meanings as in the return value of
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>.
+ Also, the callback module <c><anno>Module</anno></c>
+ does not need to export an <c>init/1</c> function.
+ </p>
+ <p>
+ Failure: If the calling process was not started by a
+ <seealso marker="proc_lib"><c>proc_lib</c></seealso>
+ start function, or if it is not registered
+ according to
+ <seealso marker="#type-server_name"><c>server_name()</c></seealso>.
+ </p>
+ </desc>
+ </func>
+
+ </funcs>
+
+
+
+ <section>
+ <title>CALLBACK FUNCTIONS</title>
+ <p>
+ The following functions should be exported from a
+ <c>gen_statem</c> callback module.
+ </p>
+ </section>
+ <funcs>
+
+ <func>
+ <name>Module:init(Args) -> Result</name>
+ <fsummary>Initialize process and internal state</fsummary>
+ <type>
+ <v>Args = term()</v>
+ <v>Result = {CallbackMode,State,Data}</v>
+ <v>&nbsp;| {CallbackMode,State,Data,Actions}</v>
+ <v>&nbsp;| {stop,Reason} | ignore</v>
+ <v>
+ CallbackMode =
+ <seealso marker="#type-callback_mode">callback_mode()</seealso>
+ </v>
+ <v>State = <seealso marker="#type-state">state()</seealso></v>
+ <v>
+ Data = <seealso marker="#type-data">data()</seealso>
+ </v>
+ <v>
+ Actions =
+ [<seealso marker="#type-action">action()</seealso>] |
+ <seealso marker="#type-action">action()</seealso>
+ </v>
+ <v>Reason = term()</v>
+ </type>
+ <desc>
+ <marker id="Module:init-1" />
+ <p>
+ Whenever a <c>gen_statem</c> is started using
+ <seealso marker="#start_link/3"><c>start_link/3,4</c></seealso>
+ or
+ <seealso marker="#start/3"><c>start/3,4</c></seealso>,
+ this function is called by the new process to initialize
+ the implementation state and server data.
+ </p>
+ <p>
+ <c>Args</c> is the <c>Args</c> argument provided to the start
+ function.
+ </p>
+ <p>
+ If the initialization is successful, the function should
+ return <c>{CallbackMode,State,Data}</c> or
+ <c>{CallbackMode,State,Data,Actions}</c>.
+ <c>CallbackMode</c> selects the
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>.
+ of the <c>gen_statem</c>.
+ <c>State</c> is the initial
+ <seealso marker="#type-state"><c>state()</c></seealso>
+ and <c>Data</c> the initial server
+ <seealso marker="#type-data"><c>data()</c></seealso>.
+ </p>
+ <p>
+ The <seealso marker="#type-action"><c>Actions</c></seealso>
+ are executed when entering the first
+ <seealso marker="#type-state">state</seealso> just as for a
+ <seealso marker="#state_function">state function</seealso>.
+ </p>
+ <p>
+ If something goes wrong during the initialization
+ the function should return <c>{stop,Reason}</c>
+ or <c>ignore</c>. See
+ <seealso marker="#start_link/3"><c>start_link/3,4</c></seealso>.
+ </p>
+ <p>
+ This function may use
+ <seealso marker="erts:erlang#throw/1"><c>throw/1</c></seealso>
+ to return <c>Result</c>.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name>Module:StateName(EventType, EventContent, Data) ->
+ StateFunctionResult
+ </name>
+ <name>Module:handle_event(EventType, EventContent,
+ State, Data) -> HandleEventResult
+ </name>
+ <fsummary>Handle an event</fsummary>
+ <type>
+ <v>
+ EventType =
+ <seealso marker="#type-event_type">event_type()</seealso>
+ </v>
+ <v>EventContent = term()</v>
+ <v>
+ State =
+ <seealso marker="#type-state">state()</seealso>
+ </v>
+ <v>
+ Data = NewData =
+ <seealso marker="#type-data">data()</seealso>
+ </v>
+ <v>
+ StateFunctionResult =
+ <seealso marker="#type-state_function_result">
+ state_function_result()
+ </seealso>
+ </v>
+ <v>
+ HandleEventResult =
+ <seealso marker="#type-handle_event_result">
+ handle_event_result()
+ </seealso>
+ </v>
+ </type>
+ <desc>
+ <p>
+ Whenever a <c>gen_statem</c> receives an event from
+ <seealso marker="#call/2"><c>call/2</c></seealso>,
+ <seealso marker="#cast/2"><c>cast/2</c></seealso> or
+ as a normal process message one of these functions is called. If
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
+ is <c>state_functions</c> then <c>Module:StateName/3</c> is called,
+ and if it is <c>handle_event_function</c>
+ then <c>Module:handle_event/4</c> is called.
+ </p>
+ <p>
+ If <c>EventType</c> is
+ <seealso marker="#type-event_type"><c>{call,From}</c></seealso>
+ the caller is waiting for a reply. The reply can be sent
+ from this or from any other
+ <seealso marker="#state_function">state function</seealso>
+ by returning with <c>{reply,From,Reply}</c> in
+ <seealso marker="#type-action"><c>Actions</c></seealso>, in
+ <seealso marker="#type-reply_action"><c>Replies</c></seealso>
+ or by calling
+ <seealso marker="#reply/2"><c>reply(From, Reply)</c></seealso>.
+ </p>
+ <p>
+ If this function returns with a next state that
+ does not match equal (<c>=/=</c>) to the current state
+ all postponed events will be retried in the next state.
+ </p>
+ <p>
+ The only difference between <c>StateFunctionResult</c> and
+ <c>HandleEventResult</c> is that for <c>StateFunctionResult</c>
+ the next state has to be an atom but for <c>HandleEventResult</c>
+ there is no restriction on the next state.
+ </p>
+ <p>
+ See <seealso marker="#type-action"><c>action()</c></seealso>
+ for options that can be set and actions that can be done
+ by <c>gen_statem</c> after returning from this function.
+ </p>
+ <p>
+ These functions may use
+ <seealso marker="erts:erlang#throw/1"><c>throw/1</c></seealso>,
+ to return the result.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name>Module:terminate(Reason, State, Data) -> Ignored</name>
+ <fsummary>Clean up before termination</fsummary>
+ <type>
+ <v>Reason = normal | shutdown | {shutdown,term()} | term()</v>
+ <v>State = <seealso marker="#type-state">state()</seealso></v>
+ <v>Data = <seealso marker="#type-data">data()</seealso></v>
+ <v>Ignored = term()</v>
+ </type>
+ <desc>
+ <p>
+ This function is called by a <c>gen_statem</c>
+ when it is about to terminate. It should be the opposite of
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ and do any necessary cleaning up. When it returns,
+ the <c>gen_statem</c> terminates with <c>Reason</c>. The return
+ value is ignored.</p>
+ <p>
+ <c>Reason</c> is a term denoting the stop reason and
+ <seealso marker="#type-state"><c>State</c></seealso>
+ is the internal state of the <c>gen_statem</c>.
+ </p>
+ <p>
+ <c>Reason</c> depends on why the <c>gen_statem</c>
+ is terminating.
+ If it is because another callback function has returned a
+ stop tuple <c>{stop,Reason}</c> in
+ <seealso marker="#type-action"><c>Actions</c></seealso>,
+ <c>Reason</c> will have the value specified in that tuple.
+ If it is due to a failure, <c>Reason</c> is the error reason.
+ </p>
+ <p>
+ If the <c>gen_statem</c> is part of a supervision tree and is
+ ordered by its supervisor to terminate, this function will be
+ called with <c>Reason = shutdown</c> if the following
+ conditions apply:</p>
+ <list type="bulleted">
+ <item>
+ the <c>gen_statem</c> has been set
+ to trap exit signals, and
+ </item>
+ <item>
+ the shutdown strategy as defined in the supervisor's
+ child specification is an integer timeout value, not
+ <c>brutal_kill</c>.
+ </item>
+ </list>
+ <p>
+ Even if the <c>gen_statem</c> is <em>not</em>
+ part of a supervision tree, this function will be called
+ if it receives an <c>'EXIT'</c> message from its parent.
+ <c>Reason</c> will be the same as
+ in the <c>'EXIT'</c> message.
+ </p>
+ <p>
+ Otherwise, the <c>gen_statem</c> will be immediately terminated.
+ </p>
+ <p>
+ Note that for any other reason than <c>normal</c>,
+ <c>shutdown</c>, or <c>{shutdown,Term}</c>
+ the <c>gen_statem</c> is assumed to terminate due to an error
+ and an error report is issued using
+ <seealso marker="kernel:error_logger#format/2">
+ <c>error_logger:format/2</c>.
+ </seealso>
+ </p>
+ <p>
+ This function may use
+ <seealso marker="erts:erlang#throw/1"><c>throw/1</c></seealso>
+ to return <c>Ignored</c>, which is ignored anyway.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name>Module:code_change(OldVsn, OldState, OldData, Extra) ->
+ Result
+ </name>
+ <fsummary>Update the internal state during upgrade/downgrade</fsummary>
+ <type>
+ <v>OldVsn = Vsn | {down,Vsn}</v>
+ <v>&nbsp;&nbsp;Vsn = term()</v>
+ <v>OldState = NewState = term()</v>
+ <v>Extra = term()</v>
+ <v>Result = {NewCallbackMode,NewState,NewData} | Reason</v>
+ <v>
+ NewCallbackMode =
+ <seealso marker="#type-callback_mode">callback_mode()</seealso>
+ </v>
+ <v>
+ OldState = NewState =
+ <seealso marker="#type-state">state()</seealso>
+ </v>
+ <v>
+ OldData = NewData =
+ <seealso marker="#type-data">data()</seealso>
+ </v>
+ <v>Reason = term()</v>
+ </type>
+ <desc>
+ <p>
+ This function is called by a <c>gen_statem</c> when it should
+ update its internal state during a release upgrade/downgrade,
+ that is when the instruction <c>{update,Module,Change,...}</c>
+ where <c>Change={advanced,Extra}</c> is given in the
+ <seealso marker="sasl:appup"><c>appup</c></seealso>
+ file. See
+ <seealso marker="doc/design_principles:release_handling#instr">
+ OTP Design Principles
+ </seealso>
+ for more information.
+ </p>
+ <p>
+ In the case of an upgrade, <c>OldVsn</c> is <c>Vsn</c>, and
+ in the case of a downgrade, <c>OldVsn</c> is
+ <c>{down,Vsn}</c>. <c>Vsn</c> is defined by the <c>vsn</c>
+ attribute(s) of the old version of the callback module
+ <c>Module</c>. If no such attribute is defined, the version
+ is the checksum of the BEAM file.
+ </p>
+ <note>
+ <p>
+ If you would dare to change
+ <seealso marker="#type-callback_mode">
+ <em>callback mode</em>
+ </seealso>
+ during release upgrade/downgrade, the upgrade is no problem
+ since the new code surely knows what <em>callback mode</em>
+ it needs, but for a downgrade this function will have to
+ know from the <c>Extra</c> argument that comes from the
+ <seealso marker="sasl:appup"><c>appup</c></seealso>
+ file what <em>callback mode</em> the old code did use.
+ It may also be possible to figure this out
+ from the <c>{down,Vsn}</c> argument since <c>Vsn</c>
+ in effect defines the old callback module version.
+ </p>
+ </note>
+ <p>
+ <c>OldState</c> and <c>OldData</c> is the internal state
+ of the <c>gen_statem</c>.
+ </p>
+ <p>
+ <c>Extra</c> is passed as-is from the <c>{advanced,Extra}</c>
+ part of the update instruction.
+ </p>
+ <p>
+ If successful, the function shall return the updated
+ internal state in an
+ <c>{NewCallbackMode,NewState,NewData}</c> tuple.
+ </p>
+ <p>
+ If the function returns <c>Reason</c>, the ongoing
+ upgrade will fail and roll back to the old release.</p>
+ <p>
+ This function may use
+ <seealso marker="erts:erlang#throw/1"><c>throw/1</c></seealso>
+ to return <c>Result</c> or <c>Reason</c>.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name>Module:format_status(Opt, [PDict,State,Data]) ->
+ Status
+ </name>
+ <fsummary>Optional function for providing a term describing the
+ current <c>gen_statem</c> status</fsummary>
+ <type>
+ <v>Opt = normal | terminate</v>
+ <v>PDict = [{Key, Value}]</v>
+ <v>
+ State =
+ <seealso marker="#type-state">state()</seealso>
+ </v>
+ <v>
+ Data =
+ <seealso marker="#type-data">data()</seealso>
+ </v>
+ <v>Key = term()</v>
+ <v>Value = term()</v>
+ <v>Status = term()</v>
+ </type>
+ <desc>
+ <note>
+ <p>
+ This callback is optional, so a callback module need not
+ export it. The <c>gen_statem</c> module provides a default
+ implementation of this function that returns
+ <c>{State,Data}</c>. If this callback fails the default
+ function will return <c>{State,Info}</c>
+ where <c>Info</c> informs of the crash but no details,
+ to hide possibly sensitive data.
+ </p>
+ </note>
+ <p>This function is called by a <c>gen_statem</c> process when:</p>
+ <list type="bulleted">
+ <item>
+ One of
+ <seealso marker="sys#get_status/1">
+ <c>sys:get_status/1,2</c>
+ </seealso>
+ is invoked to get the <c>gen_statem</c> status. <c>Opt</c> is set
+ to the atom <c>normal</c> for this case.
+ </item>
+ <item>
+ The <c>gen_statem</c> terminates abnormally and logs an error.
+ <c>Opt</c> is set to the atom <c>terminate</c> for this case.
+ </item>
+ </list>
+ <p>
+ This function is useful for customising the form and
+ appearance of the <c>gen_statem</c> status for these cases. A
+ callback module wishing to customise the
+ <seealso marker="sys#get_status/1">
+ <c>sys:get_status/1,2</c>
+ </seealso>
+ return value as well as how
+ its status appears in termination error logs exports an
+ instance of <c>format_status/2</c> that returns a term
+ describing the current status of the <c>gen_statem</c>.
+ </p>
+ <p>
+ <c>PDict</c> is the current value of the <c>gen_statem</c>'s
+ process dictionary.
+ </p>
+ <p>
+ <seealso marker="#type-state"><c>State</c></seealso>
+ is the internal state of the <c>gen_statem</c>.
+ </p>
+ <p>
+ <seealso marker="#type-data"><c>Data</c></seealso>
+ is the internal server data of the <c>gen_statem</c>.
+ </p>
+ <p>
+ The function should return <c>Status</c>, a term that
+ customises the details of the current state and status of
+ the <c>gen_statem</c>. There are no restrictions on the
+ form <c>Status</c> can take, but for the
+ <seealso marker="sys#get_status/1">
+ <c>sys:get_status/1,2</c>
+ </seealso>
+ case (when <c>Opt</c>
+ is <c>normal</c>), the recommended form for
+ the <c>Status</c> value is <c>[{data, [{"State",
+ Term}]}]</c> where <c>Term</c> provides relevant details of
+ the <c>gen_statem</c> state. Following this recommendation isn't
+ required, but doing so will make the callback module status
+ consistent with the rest of the
+ <seealso marker="sys#get_status/1">
+ <c>sys:get_status/1,2</c>
+ </seealso>
+ return value.
+ </p>
+ <p>
+ One use for this function is to return compact alternative
+ state representations to avoid having large state terms
+ printed in logfiles. Another is to hide sensitive data from
+ being written to the error log.
+ </p>
+ <p>
+ This function may use
+ <seealso marker="erts:erlang#throw/1"><c>throw/1</c></seealso>
+ to return <c>Status</c>.
+ </p>
+ </desc>
+ </func>
+
+ </funcs>
+
+ <section>
+ <title>SEE ALSO</title>
+ <p><seealso marker="gen_event"><c>gen_event(3)</c></seealso>,
+ <seealso marker="gen_fsm"><c>gen_fsm(3)</c></seealso>,
+ <seealso marker="gen_server"><c>gen_server(3)</c></seealso>,
+ <seealso marker="supervisor"><c>supervisor(3)</c></seealso>,
+ <seealso marker="proc_lib"><c>proc_lib(3)</c></seealso>,
+ <seealso marker="sys"><c>sys(3)</c></seealso></p>
+ </section>
+</erlref>
diff --git a/lib/stdlib/doc/src/proc_lib.xml b/lib/stdlib/doc/src/proc_lib.xml
index bef037076b..245580b1ba 100644
--- a/lib/stdlib/doc/src/proc_lib.xml
+++ b/lib/stdlib/doc/src/proc_lib.xml
@@ -34,9 +34,9 @@
<p>This module is used to start processes adhering to
the <seealso marker="doc/design_principles:des_princ">OTP Design Principles</seealso>. Specifically, the functions in this
module are used by the OTP standard behaviors (<c>gen_server</c>,
- <c>gen_fsm</c>, ...) when starting new processes. The functions
- can also be used to start <em>special processes</em>, user
- defined processes which comply to the OTP design principles. See
+ <c>gen_fsm</c>, <c>gen_statem</c>, ...) when starting new processes.
+ The functions can also be used to start <em>special processes</em>,
+ user defined processes which comply to the OTP design principles. See
<seealso marker="doc/design_principles:spec_proc">Sys and Proc_Lib</seealso> in OTP Design Principles for an example.</p>
<p>Some useful information is initialized when a process starts.
The registered names, or the process identifiers, of the parent
diff --git a/lib/stdlib/doc/src/ref_man.xml b/lib/stdlib/doc/src/ref_man.xml
index 82ad78e675..404873ea32 100644
--- a/lib/stdlib/doc/src/ref_man.xml
+++ b/lib/stdlib/doc/src/ref_man.xml
@@ -4,7 +4,7 @@
<application xmlns:xi="http://www.w3.org/2001/XInclude">
<header>
<copyright>
- <year>1996</year><year>2015</year>
+ <year>1996</year><year>2016</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -66,6 +66,7 @@
<xi:include href="gen_event.xml"/>
<xi:include href="gen_fsm.xml"/>
<xi:include href="gen_server.xml"/>
+ <xi:include href="gen_statem.xml"/>
<xi:include href="io.xml"/>
<xi:include href="io_lib.xml"/>
<xi:include href="lib.xml"/>
diff --git a/lib/stdlib/doc/src/specs.xml b/lib/stdlib/doc/src/specs.xml
index 0418bf7b22..45b207b13d 100644
--- a/lib/stdlib/doc/src/specs.xml
+++ b/lib/stdlib/doc/src/specs.xml
@@ -30,6 +30,7 @@
<xi:include href="../specs/specs_gen_event.xml"/>
<xi:include href="../specs/specs_gen_fsm.xml"/>
<xi:include href="../specs/specs_gen_server.xml"/>
+ <xi:include href="../specs/specs_gen_statem.xml"/>
<xi:include href="../specs/specs_io.xml"/>
<xi:include href="../specs/specs_io_lib.xml"/>
<xi:include href="../specs/specs_lib.xml"/>
diff --git a/lib/stdlib/doc/src/supervisor.xml b/lib/stdlib/doc/src/supervisor.xml
index 421306283c..29e5a732d5 100644
--- a/lib/stdlib/doc/src/supervisor.xml
+++ b/lib/stdlib/doc/src/supervisor.xml
@@ -34,8 +34,8 @@
<p>A behaviour module for implementing a supervisor, a process which
supervises other processes called child processes. A child
process can either be another supervisor or a worker process.
- Worker processes are normally implemented using one of
- the <c>gen_event</c>, <c>gen_fsm</c>, or <c>gen_server</c>
+ Worker processes are normally implemented using one of the
+ <c>gen_event</c>, <c>gen_fsm</c>, <c>gen_statem</c> or <c>gen_server</c>
behaviours. A supervisor implemented using this module will have
a standard set of interface functions and include functionality
for tracing and error reporting. Supervisors are used to build a
@@ -221,7 +221,8 @@
<p><c>modules</c> is used by the release handler during code
replacement to determine which processes are using a certain
module. As a rule of thumb, if the child process is a
- <c>supervisor</c>, <c>gen_server</c>, or <c>gen_fsm</c>,
+ <c>supervisor</c>, <c>gen_server</c>,
+ <c>gen_fsm</c> or <c>gen_statem</c>
this should be a list with one element <c>[Module]</c>,
where <c>Module</c> is the callback module. If the child
process is an event manager (<c>gen_event</c>) with a
@@ -636,6 +637,7 @@
<title>SEE ALSO</title>
<p><seealso marker="gen_event">gen_event(3)</seealso>,
<seealso marker="gen_fsm">gen_fsm(3)</seealso>,
+ <seealso marker="gen_statem">gen_statem(3)</seealso>,
<seealso marker="gen_server">gen_server(3)</seealso>,
<seealso marker="sys">sys(3)</seealso></p>
</section>
diff --git a/lib/stdlib/doc/src/sys.xml b/lib/stdlib/doc/src/sys.xml
index d80ec4dfa6..2255395f46 100644
--- a/lib/stdlib/doc/src/sys.xml
+++ b/lib/stdlib/doc/src/sys.xml
@@ -217,14 +217,18 @@
processes. For example, a <c>gen_server</c> process returns
the callback module's state, a <c>gen_fsm</c> process
returns information such as its current state name and state data,
- and a <c>gen_event</c> process returns information about each of its
+ a <c>gen_statem</c> process returns information about
+ its current state and data, and a <c>gen_event</c> process
+ returns information about each of its
registered handlers. Callback modules for <c>gen_server</c>,
- <c>gen_fsm</c>, and <c>gen_event</c> can also customise the value
+ <c>gen_fsm</c>, <c>gen_statem</c> and <c>gen_event</c>
+ can also customise the value
of <c><anno>Misc</anno></c> by exporting a <c>format_status/2</c>
function that contributes module-specific information;
- see <seealso marker="gen_server#Module:format_status/2">gen_server:format_status/2</seealso>,
- <seealso marker="gen_fsm#Module:format_status/2">gen_fsm:format_status/2</seealso>, and
- <seealso marker="gen_event#Module:format_status/2">gen_event:format_status/2</seealso>
+ see <seealso marker="gen_server#Module:format_status/2">gen_server format_status/2</seealso>,
+ <seealso marker="gen_fsm#Module:format_status/2">gen_fsm format_status/2</seealso>,
+ <seealso marker="gen_statem#Module:format_status/2">gen_statem format_status/2</seealso>, and
+ <seealso marker="gen_event#Module:format_status/2">gen_event format_status/2</seealso>
for more details.</p>
</desc>
</func>
@@ -245,6 +249,8 @@
processes. For a <c>gen_server</c> process, the returned <c><anno>State</anno></c>
is simply the callback module's state. For a <c>gen_fsm</c> process,
<c><anno>State</anno></c> is the tuple <c>{CurrentStateName, CurrentStateData}</c>.
+ For a <c>gen_statem</c> process <c><anno>State</anno></c> is
+ the tuple <c>{CurrentState,CurrentData}.</c>
For a <c>gen_event</c> process, <c><anno>State</anno></c> a list of tuples,
where each tuple corresponds to an event handler registered in the process and contains
<c>{Module, Id, HandlerState}</c>, where <c>Module</c> is the event handler's module name,
@@ -263,8 +269,9 @@
details of the exception.</p>
<p>The <c>system_get_state/1</c> function is primarily useful for user-defined
behaviours and modules that implement OTP <seealso marker="#special_process">special
- processes</seealso>. The <c>gen_server</c>, <c>gen_fsm</c>, and <c>gen_event</c> OTP
- behaviour modules export this function, and so callback modules for those behaviours
+ processes</seealso>. The <c>gen_server</c>, <c>gen_fsm</c>,
+ <c>gen_statem</c> and <c>gen_event</c> OTP
+ behaviour modules export this function, so callback modules for those behaviours
need not supply their own.</p>
<p>To obtain more information about a process, including its state, see
<seealso marker="#get_status-1">get_status/1</seealso> and
@@ -290,6 +297,8 @@
<c>gen_fsm</c> process, <c><anno>State</anno></c> is the tuple
<c>{CurrentStateName, CurrentStateData}</c>, and <c><anno>NewState</anno></c>
is a similar tuple that may contain a new state name, new state data, or both.
+ The same applies for a <c>gen_statem</c> process but
+ it names the tuple fields <c>{CurrentState,CurrentData}</c>.
For a <c>gen_event</c> process, <c><anno>State</anno></c> is the tuple
<c>{Module, Id, HandlerState}</c> where <c>Module</c> is the event handler's module name,
<c>Id</c> is the handler's ID (which is the value <c>false</c> if it was registered without
@@ -304,7 +313,8 @@
state, then regardless of process type, it may simply return its <c><anno>State</anno></c>
argument.</p>
<p>If a <c><anno>StateFun</anno></c> function crashes or throws an exception, then
- for <c>gen_server</c> and <c>gen_fsm</c> processes, the original state of the process is
+ for <c>gen_server</c>, <c>gen_fsm</c> or <c>gen_statem</c> processes,
+ the original state of the process is
unchanged. For <c>gen_event</c> processes, a crashing or failing <c><anno>StateFun</anno></c>
function means that only the state of the particular event handler it was working on when it
failed or crashed is unchanged; it can still succeed in changing the states of other event
@@ -329,7 +339,8 @@
<c>{callback_failed, StateFun, {Class, Reason}}</c>.</p>
<p>The <c>system_replace_state/2</c> function is primarily useful for user-defined behaviours and
modules that implement OTP <seealso marker="#special_process">special processes</seealso>. The
- <c>gen_server</c>, <c>gen_fsm</c>, and <c>gen_event</c> OTP behaviour modules export this function,
+ <c>gen_server</c>, <c>gen_fsm</c>, <c>gen_statem</c> and
+ <c>gen_event</c> OTP behaviour modules export this function,
and so callback modules for those behaviours need not supply their own.</p>
</desc>
</func>
diff --git a/lib/stdlib/src/Makefile b/lib/stdlib/src/Makefile
index 9f4a446ea0..302834f9d0 100644
--- a/lib/stdlib/src/Makefile
+++ b/lib/stdlib/src/Makefile
@@ -1,7 +1,7 @@
#
# %CopyrightBegin%
#
-# Copyright Ericsson AB 1996-2015. All Rights Reserved.
+# Copyright Ericsson AB 1996-2016. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
@@ -85,6 +85,7 @@ MODULES= \
gen_event \
gen_fsm \
gen_server \
+ gen_statem \
io \
io_lib \
io_lib_format \
diff --git a/lib/stdlib/src/gen.erl b/lib/stdlib/src/gen.erl
index 9811a211ae..597830cf9a 100644
--- a/lib/stdlib/src/gen.erl
+++ b/lib/stdlib/src/gen.erl
@@ -26,7 +26,8 @@
%%%
%%% The standard behaviour should export init_it/6.
%%%-----------------------------------------------------------------
--export([start/5, start/6, debug_options/1,
+-export([start/5, start/6, debug_options/2,
+ name/1, unregister_name/1, get_proc_name/1, get_parent/0,
call/3, call/4, reply/2, stop/1, stop/3]).
-export([init_it/6, init_it/7]).
@@ -124,7 +125,7 @@ init_it(GenMod, Starter, Parent, Mod, Args, Options) ->
init_it2(GenMod, Starter, Parent, self(), Mod, Args, Options).
init_it(GenMod, Starter, Parent, Name, Mod, Args, Options) ->
- case name_register(Name) of
+ case register_name(Name) of
true ->
init_it2(GenMod, Starter, Parent, Name, Mod, Args, Options);
{false, Pid} ->
@@ -297,19 +298,19 @@ where({global, Name}) -> global:whereis_name(Name);
where({via, Module, Name}) -> Module:whereis_name(Name);
where({local, Name}) -> whereis(Name).
-name_register({local, Name} = LN) ->
+register_name({local, Name} = LN) ->
try register(Name, self()) of
true -> true
catch
error:_ ->
{false, where(LN)}
end;
-name_register({global, Name} = GN) ->
+register_name({global, Name} = GN) ->
case global:register_name(Name, self()) of
yes -> true;
no -> {false, where(GN)}
end;
-name_register({via, Module, Name} = GN) ->
+register_name({via, Module, Name} = GN) ->
case Module:register_name(Name, self()) of
yes ->
true;
@@ -317,34 +318,108 @@ name_register({via, Module, Name} = GN) ->
{false, where(GN)}
end.
+name({local,Name}) -> Name;
+name({global,Name}) -> Name;
+name({via,_, Name}) -> Name;
+name(Pid) when is_pid(Pid) -> Pid.
+
+unregister_name({local,Name}) ->
+ try unregister(Name) of
+ _ -> ok
+ catch
+ _:_ -> ok
+ end;
+unregister_name({global,Name}) ->
+ _ = global:unregister_name(Name),
+ ok;
+unregister_name({via, Mod, Name}) ->
+ _ = Mod:unregister_name(Name),
+ ok;
+unregister_name(Pid) when is_pid(Pid) ->
+ ok.
+
+get_proc_name(Pid) when is_pid(Pid) ->
+ Pid;
+get_proc_name({local, Name}) ->
+ case process_info(self(), registered_name) of
+ {registered_name, Name} ->
+ Name;
+ {registered_name, _Name} ->
+ exit(process_not_registered);
+ [] ->
+ exit(process_not_registered)
+ end;
+get_proc_name({global, Name}) ->
+ case global:whereis_name(Name) of
+ undefined ->
+ exit(process_not_registered_globally);
+ Pid when Pid =:= self() ->
+ Name;
+ _Pid ->
+ exit(process_not_registered_globally)
+ end;
+get_proc_name({via, Mod, Name}) ->
+ case Mod:whereis_name(Name) of
+ undefined ->
+ exit({process_not_registered_via, Mod});
+ Pid when Pid =:= self() ->
+ Name;
+ _Pid ->
+ exit({process_not_registered_via, Mod})
+ end.
+
+get_parent() ->
+ case get('$ancestors') of
+ [Parent | _] when is_pid(Parent) ->
+ Parent;
+ [Parent | _] when is_atom(Parent) ->
+ name_to_pid(Parent);
+ _ ->
+ exit(process_was_not_started_by_proc_lib)
+ end.
+
+name_to_pid(Name) ->
+ case whereis(Name) of
+ undefined ->
+ case global:whereis_name(Name) of
+ undefined ->
+ exit(could_not_find_registered_name);
+ Pid ->
+ Pid
+ end;
+ Pid ->
+ Pid
+ end.
+
timeout(Options) ->
- case opt(timeout, Options) of
- {ok, Time} ->
+ case lists:keyfind(timeout, 1, Options) of
+ {_,Time} ->
Time;
- _ ->
+ false ->
infinity
end.
spawn_opts(Options) ->
- case opt(spawn_opt, Options) of
- {ok, Opts} ->
+ case lists:keyfind(spawn_opt, 1, Options) of
+ {_,Opts} ->
Opts;
- _ ->
+ false ->
[]
end.
-opt(Op, [{Op, Value}|_]) ->
- {ok, Value};
-opt(Op, [_|Options]) ->
- opt(Op, Options);
-opt(_, []) ->
- false.
-
-debug_options(Opts) ->
- case opt(debug, Opts) of
- {ok, Options} -> sys:debug_options(Options);
- _ -> []
+debug_options(Name, Opts) ->
+ case lists:keyfind(debug, 1, Opts) of
+ {_,Options} ->
+ try sys:debug_options(Options)
+ catch _:_ ->
+ error_logger:format(
+ "~p: ignoring erroneous debug options - ~p~n",
+ [Name,Options]),
+ []
+ end;
+ false ->
+ []
end.
format_status_header(TagLine, Pid) when is_pid(Pid) ->
diff --git a/lib/stdlib/src/gen_event.erl b/lib/stdlib/src/gen_event.erl
index 1303036168..ccacf658e9 100644
--- a/lib/stdlib/src/gen_event.erl
+++ b/lib/stdlib/src/gen_event.erl
@@ -147,16 +147,11 @@ init_it(Starter, self, Name, Mod, Args, Options) ->
init_it(Starter, self(), Name, Mod, Args, Options);
init_it(Starter, Parent, Name0, _, _, Options) ->
process_flag(trap_exit, true),
- Debug = gen:debug_options(Options),
+ Name = gen:name(Name0),
+ Debug = gen:debug_options(Name, Options),
proc_lib:init_ack(Starter, {ok, self()}),
- Name = name(Name0),
loop(Parent, Name, [], Debug, false).
-name({local,Name}) -> Name;
-name({global,Name}) -> Name;
-name({via,_, Name}) -> Name;
-name(Pid) when is_pid(Pid) -> Pid.
-
-spec add_handler(emgr_ref(), handler(), term()) -> term().
add_handler(M, Handler, Args) -> rpc(M, {add_handler, Handler, Args}).
diff --git a/lib/stdlib/src/gen_fsm.erl b/lib/stdlib/src/gen_fsm.erl
index 2b4b76105e..6e7528fd98 100644
--- a/lib/stdlib/src/gen_fsm.erl
+++ b/lib/stdlib/src/gen_fsm.erl
@@ -305,64 +305,11 @@ enter_loop(Mod, Options, StateName, StateData, Timeout) ->
enter_loop(Mod, Options, StateName, StateData, self(), Timeout).
enter_loop(Mod, Options, StateName, StateData, ServerName, Timeout) ->
- Name = get_proc_name(ServerName),
- Parent = get_parent(),
- Debug = gen:debug_options(Options),
+ Name = gen:get_proc_name(ServerName),
+ Parent = gen:get_parent(),
+ Debug = gen:debug_options(Name, Options),
loop(Parent, Name, StateName, StateData, Mod, Timeout, Debug).
-get_proc_name(Pid) when is_pid(Pid) ->
- Pid;
-get_proc_name({local, Name}) ->
- case process_info(self(), registered_name) of
- {registered_name, Name} ->
- Name;
- {registered_name, _Name} ->
- exit(process_not_registered);
- [] ->
- exit(process_not_registered)
- end;
-get_proc_name({global, Name}) ->
- case global:whereis_name(Name) of
- undefined ->
- exit(process_not_registered_globally);
- Pid when Pid =:= self() ->
- Name;
- _Pid ->
- exit(process_not_registered_globally)
- end;
-get_proc_name({via, Mod, Name}) ->
- case Mod:whereis_name(Name) of
- undefined ->
- exit({process_not_registered_via, Mod});
- Pid when Pid =:= self() ->
- Name;
- _Pid ->
- exit({process_not_registered_via, Mod})
- end.
-
-get_parent() ->
- case get('$ancestors') of
- [Parent | _] when is_pid(Parent) ->
- Parent;
- [Parent | _] when is_atom(Parent) ->
- name_to_pid(Parent);
- _ ->
- exit(process_was_not_started_by_proc_lib)
- end.
-
-name_to_pid(Name) ->
- case whereis(Name) of
- undefined ->
- case global:whereis_name(Name) of
- undefined ->
- exit(could_not_find_registered_name);
- Pid ->
- Pid
- end;
- Pid ->
- Pid
- end.
-
%%% ---------------------------------------------------
%%% Initiate the new process.
%%% Register the name using the Rfunc function
@@ -373,8 +320,8 @@ name_to_pid(Name) ->
init_it(Starter, self, Name, Mod, Args, Options) ->
init_it(Starter, self(), Name, Mod, Args, Options);
init_it(Starter, Parent, Name0, Mod, Args, Options) ->
- Name = name(Name0),
- Debug = gen:debug_options(Options),
+ Name = gen:name(Name0),
+ Debug = gen:debug_options(Name, Options),
case catch Mod:init(Args) of
{ok, StateName, StateData} ->
proc_lib:init_ack(Starter, {ok, self()}),
@@ -383,15 +330,15 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
proc_lib:init_ack(Starter, {ok, self()}),
loop(Parent, Name, StateName, StateData, Mod, Timeout, Debug);
{stop, Reason} ->
- unregister_name(Name0),
+ gen:unregister_name(Name0),
proc_lib:init_ack(Starter, {error, Reason}),
exit(Reason);
ignore ->
- unregister_name(Name0),
+ gen:unregister_name(Name0),
proc_lib:init_ack(Starter, ignore),
exit(normal);
{'EXIT', Reason} ->
- unregister_name(Name0),
+ gen:unregister_name(Name0),
proc_lib:init_ack(Starter, {error, Reason}),
exit(Reason);
Else ->
@@ -400,20 +347,6 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
exit(Error)
end.
-name({local,Name}) -> Name;
-name({global,Name}) -> Name;
-name({via,_, Name}) -> Name;
-name(Pid) when is_pid(Pid) -> Pid.
-
-unregister_name({local,Name}) ->
- _ = (catch unregister(Name));
-unregister_name({global,Name}) ->
- _ = global:unregister_name(Name);
-unregister_name({via, Mod, Name}) ->
- _ = Mod:unregister_name(Name);
-unregister_name(Pid) when is_pid(Pid) ->
- Pid.
-
%%-----------------------------------------------------------------
%% The MAIN loop
%%-----------------------------------------------------------------
diff --git a/lib/stdlib/src/gen_server.erl b/lib/stdlib/src/gen_server.erl
index fa6fff6dca..5800aca66f 100644
--- a/lib/stdlib/src/gen_server.erl
+++ b/lib/stdlib/src/gen_server.erl
@@ -304,9 +304,9 @@ enter_loop(Mod, Options, State, Timeout) ->
enter_loop(Mod, Options, State, self(), Timeout).
enter_loop(Mod, Options, State, ServerName, Timeout) ->
- Name = get_proc_name(ServerName),
- Parent = get_parent(),
- Debug = debug_options(Name, Options),
+ Name = gen:get_proc_name(ServerName),
+ Parent = gen:get_parent(),
+ Debug = gen:debug_options(Name, Options),
loop(Parent, Name, State, Mod, Timeout, Debug).
%%%========================================================================
@@ -323,8 +323,8 @@ enter_loop(Mod, Options, State, ServerName, Timeout) ->
init_it(Starter, self, Name, Mod, Args, Options) ->
init_it(Starter, self(), Name, Mod, Args, Options);
init_it(Starter, Parent, Name0, Mod, Args, Options) ->
- Name = name(Name0),
- Debug = debug_options(Name, Options),
+ Name = gen:name(Name0),
+ Debug = gen:debug_options(Name, Options),
case catch Mod:init(Args) of
{ok, State} ->
proc_lib:init_ack(Starter, {ok, self()}),
@@ -339,15 +339,15 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
%% (Otherwise, the parent process could get
%% an 'already_started' error if it immediately
%% tried starting the process again.)
- unregister_name(Name0),
+ gen:unregister_name(Name0),
proc_lib:init_ack(Starter, {error, Reason}),
exit(Reason);
ignore ->
- unregister_name(Name0),
+ gen:unregister_name(Name0),
proc_lib:init_ack(Starter, ignore),
exit(normal);
{'EXIT', Reason} ->
- unregister_name(Name0),
+ gen:unregister_name(Name0),
proc_lib:init_ack(Starter, {error, Reason}),
exit(Reason);
Else ->
@@ -356,20 +356,6 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
exit(Error)
end.
-name({local,Name}) -> Name;
-name({global,Name}) -> Name;
-name({via,_, Name}) -> Name;
-name(Pid) when is_pid(Pid) -> Pid.
-
-unregister_name({local,Name}) ->
- _ = (catch unregister(Name));
-unregister_name({global,Name}) ->
- _ = global:unregister_name(Name);
-unregister_name({via, Mod, Name}) ->
- _ = Mod:unregister_name(Name);
-unregister_name(Pid) when is_pid(Pid) ->
- Pid.
-
%%%========================================================================
%%% Internal functions
%%%========================================================================
@@ -858,86 +844,6 @@ error_info(Reason, Name, Msg, State, Debug) ->
sys:print_log(Debug),
ok.
-%%% ---------------------------------------------------
-%%% Misc. functions.
-%%% ---------------------------------------------------
-
-opt(Op, [{Op, Value}|_]) ->
- {ok, Value};
-opt(Op, [_|Options]) ->
- opt(Op, Options);
-opt(_, []) ->
- false.
-
-debug_options(Name, Opts) ->
- case opt(debug, Opts) of
- {ok, Options} -> dbg_opts(Name, Options);
- _ -> []
- end.
-
-dbg_opts(Name, Opts) ->
- case catch sys:debug_options(Opts) of
- {'EXIT',_} ->
- format("~p: ignoring erroneous debug options - ~p~n",
- [Name, Opts]),
- [];
- Dbg ->
- Dbg
- end.
-
-get_proc_name(Pid) when is_pid(Pid) ->
- Pid;
-get_proc_name({local, Name}) ->
- case process_info(self(), registered_name) of
- {registered_name, Name} ->
- Name;
- {registered_name, _Name} ->
- exit(process_not_registered);
- [] ->
- exit(process_not_registered)
- end;
-get_proc_name({global, Name}) ->
- case global:whereis_name(Name) of
- undefined ->
- exit(process_not_registered_globally);
- Pid when Pid =:= self() ->
- Name;
- _Pid ->
- exit(process_not_registered_globally)
- end;
-get_proc_name({via, Mod, Name}) ->
- case Mod:whereis_name(Name) of
- undefined ->
- exit({process_not_registered_via, Mod});
- Pid when Pid =:= self() ->
- Name;
- _Pid ->
- exit({process_not_registered_via, Mod})
- end.
-
-get_parent() ->
- case get('$ancestors') of
- [Parent | _] when is_pid(Parent)->
- Parent;
- [Parent | _] when is_atom(Parent)->
- name_to_pid(Parent);
- _ ->
- exit(process_was_not_started_by_proc_lib)
- end.
-
-name_to_pid(Name) ->
- case whereis(Name) of
- undefined ->
- case global:whereis_name(Name) of
- undefined ->
- exit(could_not_find_registered_name);
- Pid ->
- Pid
- end;
- Pid ->
- Pid
- end.
-
%%-----------------------------------------------------------------
%% Status information
%%-----------------------------------------------------------------
diff --git a/lib/stdlib/src/gen_statem.erl b/lib/stdlib/src/gen_statem.erl
new file mode 100644
index 0000000000..c85c521d8e
--- /dev/null
+++ b/lib/stdlib/src/gen_statem.erl
@@ -0,0 +1,1257 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2016. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(gen_statem).
+
+%% API
+-export(
+ [start/3,start/4,start_link/3,start_link/4,
+ stop/1,stop/3,
+ cast/2,call/2,call/3,
+ enter_loop/5,enter_loop/6,enter_loop/7,
+ reply/1,reply/2]).
+
+%% gen callbacks
+-export(
+ [init_it/6]).
+
+%% sys callbacks
+-export(
+ [system_continue/3,
+ system_terminate/4,
+ system_code_change/4,
+ system_get_state/1,
+ system_replace_state/2,
+ format_status/2]).
+
+%% Internal callbacks
+-export(
+ [wakeup_from_hibernate/3]).
+
+%% Type exports for templates
+-export_type(
+ [event_type/0,
+ callback_mode/0,
+ state_function_result/0,
+ handle_event_result/0,
+ action/0]).
+
+%% Fix problem for doc build
+-export_type([transition_option/0]).
+
+%%%==========================================================================
+%%% Interface functions.
+%%%==========================================================================
+
+-type from() ::
+ {To :: pid(), Tag :: term()}. % Reply-to specifier for call
+
+-type state() ::
+ state_name() | % For state callback function StateName/5
+ term(). % For state callback function handle_event/5
+
+-type state_name() :: atom().
+
+-type data() :: term().
+
+-type event_type() ::
+ {'call',From :: from()} | 'cast' |
+ 'info' | 'timeout' | 'internal'.
+
+-type callback_mode() :: 'state_functions' | 'handle_event_function'.
+
+-type transition_option() ::
+ postpone() | hibernate() | event_timeout().
+-type postpone() ::
+ %% If 'true' postpone the current event
+ %% and retry it when the state changes (=/=)
+ boolean().
+-type hibernate() ::
+ %% If 'true' hibernate the server instead of going into receive
+ boolean().
+-type event_timeout() ::
+ %% Generate a ('timeout', EventContent, ...) event after Time
+ %% unless some other event is delivered
+ Time :: timeout().
+
+-type action() ::
+ %% During a state change:
+ %% * NextState and NewData are set.
+ %% * All action()s are executed in order of apperance.
+ %% * Postponing the current event is performed
+ %% iff 'postpone' is 'true'.
+ %% * A state timer is started iff 'timeout' is set.
+ %% * Pending events are processed or if there are
+ %% no pending events the server goes into receive
+ %% or hibernate (iff 'hibernate' is 'true')
+ %%
+ %% These action()s are executed in order of appearence
+ %% in the containing list. The ones that set options
+ %% will override any previous so the last of each kind wins.
+ %%
+ 'postpone' | % Set the postpone option
+ {'postpone', Postpone :: postpone()} |
+ %%
+ 'hibernate' | % Set the hibernate option
+ {'hibernate', Hibernate :: hibernate()} |
+ %%
+ (Timeout :: event_timeout()) | % {timeout,Timeout}
+ {'timeout', % Set the event timeout option
+ Time :: event_timeout(), EventContent :: term()} |
+ %%
+ reply_action() |
+ %%
+ %% All 'next_event' events are kept in a list and then
+ %% inserted at state changes so the first in the
+ %% action() list is the first to be delivered.
+ {'next_event', % Insert event as the next to handle
+ EventType :: event_type(),
+ EventContent :: term()}.
+-type reply_action() ::
+ {'reply', % Reply to a caller
+ From :: from(), Reply :: term()}.
+
+-type state_function_result() ::
+ {'next_state', % {next_state,NextStateName,NewData,[]}
+ NextStateName :: state_name(),
+ NewData :: data()} |
+ {'next_state', % State transition, maybe to the same state
+ NextStateName :: state_name(),
+ NewData :: data(),
+ Actions :: [action()] | action()} |
+ common_state_callback_result().
+-type handle_event_result() ::
+ {'next_state', % {next_state,NextState,NewData,[]}
+ NextState :: state(),
+ NewData :: data()} |
+ {'next_state', % State transition, maybe to the same state
+ NextState :: state(),
+ NewData :: data(),
+ Actions :: [action()] | action()} |
+ common_state_callback_result().
+-type common_state_callback_result() ::
+ 'stop' | % {stop,normal}
+ {'stop', % Stop the server
+ Reason :: term()} |
+ {'stop', % Stop the server
+ Reason :: term(),
+ NewData :: data()} |
+ {'stop_and_reply', % Reply then stop the server
+ Reason :: term(),
+ Replies :: [reply_action()] | reply_action()} |
+ {'stop_and_reply', % Reply then stop the server
+ Reason :: term(),
+ Replies :: [reply_action()] | reply_action(),
+ NewData :: data()} |
+ {'keep_state', % {keep_state,NewData,[]}
+ NewData :: data()} |
+ {'keep_state', % Keep state, change data
+ NewData :: data(),
+ Actions :: [action()] | action()} |
+ 'keep_state_and_data' | % {keep_state_and_data,[]}
+ {'keep_state_and_data', % Keep state and data -> only actions
+ Actions :: [action()] | action()}.
+
+
+%% The state machine init function. It is called only once and
+%% the server is not running until this function has returned
+%% an {ok, ...} tuple. Thereafter the state callbacks are called
+%% for all events to this server.
+-callback init(Args :: term()) ->
+ {callback_mode(), state(), data()} |
+ {callback_mode(), state(), data(), [action()] | action()} |
+ 'ignore' |
+ {'stop', Reason :: term()}.
+
+%% Example state callback for callback_mode() =:= state_functions
+%% state name 'state_name'.
+%%
+%% In this mode all states has to be type state_name() i.e atom().
+%%
+%% Note that state callbacks and only state callbacks have arity 5
+%% and that is intended.
+-callback state_name(
+ event_type(),
+ EventContent :: term(),
+ Data :: data()) ->
+ state_function_result().
+%%
+%% State callback for callback_mode() =:= handle_event_function.
+%%
+%% Note that state callbacks and only state callbacks have arity 5
+%% and that is intended.
+-callback handle_event(
+ event_type(),
+ EventContent :: term(),
+ State :: state(), % Current state
+ Data :: data()) ->
+ handle_event_result().
+
+%% Clean up before the server terminates.
+-callback terminate(
+ Reason :: 'normal' | 'shutdown' | {'shutdown', term()}
+ | term(),
+ State :: state(),
+ Data :: data()) ->
+ any().
+
+%% Note that the new code can expect to get an OldState from
+%% the old code version not only in code_change/4 but in the first
+%% state callback function called thereafter
+-callback code_change(
+ OldVsn :: term() | {'down', term()},
+ OldState :: state(),
+ OldData :: data(),
+ Extra :: term()) ->
+ {NewCallbackMode :: callback_mode(),
+ NewState :: state(),
+ NewData :: data()}.
+
+%% Format the callback module state in some sensible that is
+%% often condensed way. For StatusOption =:= 'normal' the perferred
+%% return term is [{data,[{"State",FormattedState}]}], and for
+%% StatusOption =:= 'terminate' it is just FormattedState.
+-callback format_status(
+ StatusOption,
+ [ [{Key :: term(), Value :: term()}] |
+ state() |
+ data()]) ->
+ Status :: term() when
+ StatusOption :: 'normal' | 'terminate'.
+
+-optional_callbacks(
+ [init/1, % One may use enter_loop/5,6,7 instead
+ format_status/2, % Has got a default implementation
+ %%
+ state_name/3, % Example for callback_mode =:= state_functions:
+ %% there has to be a StateName/5 callback function for every StateName.
+ %%
+ handle_event/4]). % For callback_mode =:= handle_event_function
+
+%% Type validation functions
+callback_mode(CallbackMode) ->
+ case CallbackMode of
+ state_functions ->
+ true;
+ handle_event_function ->
+ true;
+ _ ->
+ false
+ end.
+%%
+from({Pid,_}) when is_pid(Pid) ->
+ true;
+from(_) ->
+ false.
+%%
+event_type({call,From}) ->
+ from(From);
+event_type(Type) ->
+ case Type of
+ cast ->
+ true;
+ info ->
+ true;
+ timeout ->
+ true;
+ internal ->
+ true;
+ _ ->
+ false
+ end.
+
+
+
+-define(
+ STACKTRACE(),
+ try throw(ok) catch _ -> erlang:get_stacktrace() end).
+
+-define(
+ TERMINATE(Class, Reason, Debug, S, Q),
+ terminate(
+ begin Class end,
+ begin Reason end,
+ ?STACKTRACE(),
+ begin Debug end,
+ begin S end,
+ begin Q end)).
+
+%%%==========================================================================
+%%% API
+
+-type server_name() ::
+ {'global', GlobalName :: term()}
+ | {'via', RegMod :: module(), Name :: term()}
+ | {'local', atom()}.
+-type server_ref() ::
+ {'global', GlobalName :: term()}
+ | {'via', RegMod :: module(), ViaName :: term()}
+ | (LocalName :: atom())
+ | {Name :: atom(), Node :: atom()}
+ | pid().
+-type debug_opt() ::
+ {'debug',
+ Dbgs ::
+ ['trace' | 'log' | 'statistics' | 'debug'
+ | {'logfile', string()}]}.
+-type start_opt() ::
+ debug_opt()
+ | {'timeout', Time :: timeout()}
+ | {'spawn_opt', [proc_lib:spawn_option()]}.
+-type start_ret() :: {'ok', pid()} | 'ignore' | {'error', term()}.
+
+
+
+%% Start a state machine
+-spec start(
+ Module :: module(), Args :: term(), Opts :: [start_opt()]) ->
+ start_ret().
+start(Module, Args, Opts) ->
+ gen:start(?MODULE, nolink, Module, Args, Opts).
+%%
+-spec start(
+ ServerName :: server_name(),
+ Module :: module(), Args :: term(), Opts :: [start_opt()]) ->
+ start_ret().
+start(ServerName, Module, Args, Opts) ->
+ gen:start(?MODULE, nolink, ServerName, Module, Args, Opts).
+
+%% Start and link to a state machine
+-spec start_link(
+ Module :: module(), Args :: term(), Opts :: [start_opt()]) ->
+ start_ret().
+start_link(Module, Args, Opts) ->
+ gen:start(?MODULE, link, Module, Args, Opts).
+%%
+-spec start_link(
+ ServerName :: server_name(),
+ Module :: module(), Args :: term(), Opts :: [start_opt()]) ->
+ start_ret().
+start_link(ServerName, Module, Args, Opts) ->
+ gen:start(?MODULE, link, ServerName, Module, Args, Opts).
+
+%% Stop a state machine
+-spec stop(ServerRef :: server_ref()) -> ok.
+stop(ServerRef) ->
+ gen:stop(ServerRef).
+%%
+-spec stop(
+ ServerRef :: server_ref(),
+ Reason :: term(),
+ Timeout :: timeout()) -> ok.
+stop(ServerRef, Reason, Timeout) ->
+ gen:stop(ServerRef, Reason, Timeout).
+
+%% Send an event to a state machine that arrives with type 'event'
+-spec cast(ServerRef :: server_ref(), Msg :: term()) -> ok.
+cast({global,Name}, Msg) ->
+ try global:send(Name, wrap_cast(Msg)) of
+ _ -> ok
+ catch
+ _:_ -> ok
+ end;
+cast({via,RegMod,Name}, Msg) ->
+ try RegMod:send(Name, wrap_cast(Msg)) of
+ _ -> ok
+ catch
+ _:_ -> ok
+ end;
+cast({Name,Node} = ServerRef, Msg) when is_atom(Name), is_atom(Node) ->
+ send(ServerRef, wrap_cast(Msg));
+cast(ServerRef, Msg) when is_atom(ServerRef) ->
+ send(ServerRef, wrap_cast(Msg));
+cast(ServerRef, Msg) when is_pid(ServerRef) ->
+ send(ServerRef, wrap_cast(Msg)).
+
+%% Call a state machine (synchronous; a reply is expected) that
+%% arrives with type {call,From}
+-spec call(ServerRef :: server_ref(), Request :: term()) -> Reply :: term().
+call(ServerRef, Request) ->
+ call(ServerRef, Request, infinity).
+%%
+-spec call(
+ ServerRef :: server_ref(),
+ Request :: term(),
+ Timeout :: timeout()) ->
+ Reply :: term().
+call(ServerRef, Request, infinity) ->
+ try gen:call(ServerRef, '$gen_call', Request, infinity) of
+ {ok,Reply} ->
+ Reply
+ catch
+ Class:Reason ->
+ erlang:raise(
+ Class,
+ {Reason,{?MODULE,call,[ServerRef,Request,infinity]}},
+ erlang:get_stacktrace())
+ end;
+call(ServerRef, Request, Timeout) ->
+ %% Call server through proxy process to dodge any late reply
+ Ref = make_ref(),
+ Self = self(),
+ Pid = spawn(
+ fun () ->
+ Self !
+ try gen:call(
+ ServerRef, '$gen_call', Request, Timeout) of
+ Result ->
+ {Ref,Result}
+ catch Class:Reason ->
+ {Ref,Class,Reason,erlang:get_stacktrace()}
+ end
+ end),
+ Mref = monitor(process, Pid),
+ receive
+ {Ref,Result} ->
+ demonitor(Mref, [flush]),
+ case Result of
+ {ok,Reply} ->
+ Reply
+ end;
+ {Ref,Class,Reason,Stacktrace} ->
+ demonitor(Mref, [flush]),
+ erlang:raise(
+ Class,
+ {Reason,{?MODULE,call,[ServerRef,Request,Timeout]}},
+ Stacktrace);
+ {'DOWN',Mref,_,_,Reason} ->
+ %% There is a theoretical possibility that the
+ %% proxy process gets killed between try--of and !
+ %% so this clause is in case of that
+ exit(Reason)
+ end.
+
+%% Reply from a state machine callback to whom awaits in call/2
+-spec reply([reply_action()] | reply_action()) -> ok.
+reply({reply,From,Reply}) ->
+ reply(From, Reply);
+reply(Replies) when is_list(Replies) ->
+ replies(Replies).
+%%
+-spec reply(From :: from(), Reply :: term()) -> ok.
+reply({To,Tag}, Reply) when is_pid(To) ->
+ Msg = {Tag,Reply},
+ try To ! Msg of
+ _ ->
+ ok
+ catch
+ _:_ -> ok
+ end.
+
+%% Instead of starting the state machine through start/3,4
+%% or start_link/3,4 turn the current process presumably
+%% started by proc_lib into a state machine using
+%% the same arguments as you would have returned from init/1
+-spec enter_loop(
+ Module :: module(), Opts :: [debug_opt()],
+ CallbackMode :: callback_mode(),
+ State :: state(), Data :: data()) ->
+ no_return().
+enter_loop(Module, Opts, CallbackMode, State, Data) ->
+ enter_loop(Module, Opts, CallbackMode, State, Data, self()).
+%%
+-spec enter_loop(
+ Module :: module(), Opts :: [debug_opt()],
+ CallbackMode :: callback_mode(),
+ State :: state(), Data :: data(),
+ Server_or_Actions ::
+ server_name() | pid() | [action()]) ->
+ no_return().
+enter_loop(Module, Opts, CallbackMode, State, Data, Server_or_Actions) ->
+ if
+ is_list(Server_or_Actions) ->
+ enter_loop(
+ Module, Opts, CallbackMode, State, Data,
+ self(), Server_or_Actions);
+ true ->
+ enter_loop(
+ Module, Opts, CallbackMode, State, Data,
+ Server_or_Actions, [])
+ end.
+%%
+-spec enter_loop(
+ Module :: module(), Opts :: [debug_opt()],
+ CallbackMode :: callback_mode(),
+ State :: state(), Data :: data(),
+ Server :: server_name() | pid(),
+ Actions :: [action()] | action()) ->
+ no_return().
+enter_loop(Module, Opts, CallbackMode, State, Data, Server, Actions) ->
+ is_atom(Module) orelse error({atom,Module}),
+ callback_mode(CallbackMode) orelse error({callback_mode,CallbackMode}),
+ Parent = gen:get_parent(),
+ enter(Module, Opts, CallbackMode, State, Data, Server, Actions, Parent).
+
+%%---------------------------------------------------------------------------
+%% API helpers
+
+wrap_cast(Event) ->
+ {'$gen_cast',Event}.
+
+replies([{reply,From,Reply}|Replies]) ->
+ reply(From, Reply),
+ replies(Replies);
+replies([]) ->
+ ok.
+
+%% Might actually not send the message in case of caught exception
+send(Proc, Msg) ->
+ try erlang:send(Proc, Msg, [noconnect]) of
+ noconnect ->
+ _ = spawn(erlang, send, [Proc,Msg]),
+ ok;
+ ok ->
+ ok
+ catch
+ _:_ ->
+ ok
+ end.
+
+%% Here init_it/6 and enter_loop/5,6,7 functions converge
+enter(Module, Opts, CallbackMode, State, Data, Server, Actions, Parent) ->
+ %% The values should already have been type checked
+ Name = gen:get_proc_name(Server),
+ Debug = gen:debug_options(Name, Opts),
+ PrevState = make_ref(), % Will be discarded by loop_event_actions/9
+ NewActions =
+ if
+ is_list(Actions) ->
+ Actions ++ [{postpone,false}];
+ true ->
+ [Actions,{postpone,false}]
+ end,
+ S = #{
+ callback_mode => CallbackMode,
+ module => Module,
+ name => Name,
+ state => PrevState,
+ data => Data,
+ timer => undefined,
+ postponed => [],
+ hibernate => false},
+ loop_event_actions(
+ Parent, Debug, S, [],
+ {event,undefined}, % Will be discarded thanks to {postpone,false}
+ PrevState, State, Data, NewActions).
+
+%%%==========================================================================
+%%% gen callbacks
+
+init_it(Starter, self, ServerRef, Module, Args, Opts) ->
+ init_it(Starter, self(), ServerRef, Module, Args, Opts);
+init_it(Starter, Parent, ServerRef, Module, Args, Opts) ->
+ try Module:init(Args) of
+ Result ->
+ init_result(Starter, Parent, ServerRef, Module, Result, Opts)
+ catch
+ Result ->
+ init_result(Starter, Parent, ServerRef, Module, Result, Opts);
+ Class:Reason ->
+ gen:unregister_name(ServerRef),
+ proc_lib:init_ack(Starter, {error,Reason}),
+ erlang:raise(Class, Reason, erlang:get_stacktrace())
+ end.
+
+%%---------------------------------------------------------------------------
+%% gen callbacks helpers
+
+init_result(Starter, Parent, ServerRef, Module, Result, Opts) ->
+ case Result of
+ {CallbackMode,State,Data} ->
+ case callback_mode(CallbackMode) of
+ true ->
+ proc_lib:init_ack(Starter, {ok,self()}),
+ enter(
+ Module, Opts, CallbackMode, State, Data,
+ ServerRef, [], Parent);
+ false ->
+ Error = {callback_mode,CallbackMode},
+ proc_lib:init_ack(Starter, {error,Error}),
+ exit(Error)
+ end;
+ {CallbackMode,State,Data,Actions} ->
+ case callback_mode(CallbackMode) of
+ true ->
+ proc_lib:init_ack(Starter, {ok,self()}),
+ enter(
+ Module, Opts, CallbackMode, State, Data,
+ ServerRef, Actions, Parent);
+ false ->
+ Error = {callback_mode,CallbackMode},
+ proc_lib:init_ack(Starter, {error,Error}),
+ exit(Error)
+ end;
+ {stop,Reason} ->
+ gen:unregister_name(ServerRef),
+ proc_lib:init_ack(Starter, {error,Reason}),
+ exit(Reason);
+ ignore ->
+ gen:unregister_name(ServerRef),
+ proc_lib:init_ack(Starter, ignore),
+ exit(normal);
+ _ ->
+ Error = {bad_return_value,Result},
+ proc_lib:init_ack(Starter, {error,Error}),
+ exit(Error)
+ end.
+
+%%%==========================================================================
+%%% sys callbacks
+
+system_continue(Parent, Debug, S) ->
+ loop(Parent, Debug, S).
+
+system_terminate(Reason, _Parent, Debug, S) ->
+ ?TERMINATE(exit, Reason, Debug, S, []).
+
+system_code_change(
+ #{module := Module,
+ state := State,
+ data := Data} = S,
+ _Mod, OldVsn, Extra) ->
+ case
+ try Module:code_change(OldVsn, State, Data, Extra)
+ catch
+ Result -> Result
+ end
+ of
+ {NewCallbackMode,NewState,NewData} ->
+ callback_mode(NewCallbackMode) orelse
+ error({callback_mode,NewCallbackMode}),
+ {ok,S#{state := NewState, data := NewData}};
+ {ok,_} = Error ->
+ error({case_clause,Error});
+ Error ->
+ Error
+ end.
+
+system_get_state(#{state := State, data := Data}) ->
+ {ok,{State,Data}}.
+
+system_replace_state(
+ StateFun,
+ #{state := State,
+ data := Data} = S) ->
+ {NewState,NewData} = Result = StateFun({State,Data}),
+ {ok,Result,S#{state := NewState, data := NewData}}.
+
+format_status(
+ Opt,
+ [PDict,SysState,Parent,Debug,
+ #{name := Name, postponed := P} = S]) ->
+ Header = gen:format_status_header("Status for state machine", Name),
+ Log = sys:get_debug(log, Debug, []),
+ [{header,Header},
+ {data,
+ [{"Status",SysState},
+ {"Parent",Parent},
+ {"Logged Events",Log},
+ {"Postponed",P}]} |
+ case format_status(Opt, PDict, S) of
+ L when is_list(L) -> L;
+ T -> [T]
+ end].
+
+%%---------------------------------------------------------------------------
+%% Format debug messages. Print them as the call-back module sees
+%% them, not as the real erlang messages. Use trace for that.
+%%---------------------------------------------------------------------------
+
+print_event(Dev, {in,Event}, #{name := Name}) ->
+ io:format(
+ Dev, "*DBG* ~p received ~s~n",
+ [Name,event_string(Event)]);
+print_event(Dev, {out,Reply,{To,_Tag}}, #{name := Name}) ->
+ io:format(
+ Dev, "*DBG* ~p sent ~p to ~p~n",
+ [Name,Reply,To]);
+print_event(Dev, {Tag,Event,NewState}, #{name := Name, state := State}) ->
+ StateString =
+ case NewState of
+ State ->
+ io_lib:format("~p", [State]);
+ _ ->
+ io_lib:format("~p => ~p", [State,NewState])
+ end,
+ io:format(
+ Dev, "*DBG* ~p ~w ~s in state ~s~n",
+ [Name,Tag,event_string(Event),StateString]).
+
+event_string(Event) ->
+ case Event of
+ {{call,{Pid,_Tag}},Request} ->
+ io_lib:format("call ~p from ~w", [Request,Pid]);
+ {Tag,Content} ->
+ io_lib:format("~w ~p", [Tag,Content])
+ end.
+
+sys_debug(Debug, S, Entry) ->
+ case Debug of
+ [] ->
+ Debug;
+ _ ->
+ sys:handle_debug(Debug, fun print_event/3, S, Entry)
+ end.
+
+%%%==========================================================================
+%%% Internal callbacks
+
+wakeup_from_hibernate(Parent, Debug, S) ->
+ %% It is a new message that woke us up so we have to receive it now
+ loop_receive(Parent, Debug, S).
+
+%%%==========================================================================
+%%% State Machine engine implementation of proc_lib/gen server
+
+%% Server loop, consists of all loop* functions
+%% and some detours through sys and proc_lib
+
+%% Entry point for system_continue/3
+loop(Parent, Debug, #{hibernate := Hib} = S) ->
+ case Hib of
+ true ->
+ %% Does not return but restarts process at
+ %% wakeup_from_hibernate/3 that jumps to loop_receive/3
+ proc_lib:hibernate(
+ ?MODULE, wakeup_from_hibernate, [Parent,Debug,S]),
+ error(
+ {should_not_have_arrived_here_but_instead_in,
+ {wakeup_from_hibernate,3}});
+ false ->
+ loop_receive(Parent, Debug, S)
+ end.
+
+%% Entry point for wakeup_from_hibernate/3
+loop_receive(Parent, Debug, #{timer := Timer} = S) ->
+ receive
+ Msg ->
+ case Msg of
+ {system,Pid,Req} ->
+ #{hibernate := Hibernate} = S,
+ %% Does not return but tail recursively calls
+ %% system_continue/3 that jumps to loop/3
+ sys:handle_system_msg(
+ Req, Pid, Parent, ?MODULE, Debug, S, Hibernate);
+ {'EXIT',Parent,Reason} = EXIT ->
+ %% EXIT is not a 2-tuple and therefore
+ %% not an event and has no event_type(),
+ %% but this will stand out in the crash report...
+ ?TERMINATE(exit, Reason, Debug, S, [EXIT]);
+ {timeout,Timer,Content} when Timer =/= undefined ->
+ loop_event(
+ Parent, Debug, S, {timeout,Content});
+ _ ->
+ %% Cancel Timer if running
+ case Timer of
+ undefined ->
+ ok;
+ _ ->
+ case erlang:cancel_timer(Timer) of
+ TimeLeft when is_integer(TimeLeft) ->
+ ok;
+ false ->
+ receive
+ {timeout,Timer,_} ->
+ ok
+ after 0 ->
+ ok
+ end
+ end
+ end,
+ Event =
+ case Msg of
+ {'$gen_call',From,Request} ->
+ {{call,From},Request};
+ {'$gen_cast',E} ->
+ {cast,E};
+ _ ->
+ {info,Msg}
+ end,
+ loop_event(Parent, Debug, S, Event)
+ end
+ end.
+
+loop_event(Parent, Debug, S, Event) ->
+ %% The timer field in S is now invalid and ignored
+ %% until we get back to loop/3
+ NewDebug = sys_debug(Debug, S, {in,Event}),
+ %% Here the queue of not yet processed events is created
+ loop_events(Parent, NewDebug, S, [Event]).
+
+%% Process first the event queue, or if it is empty
+%% loop back to receive a new event
+loop_events(Parent, Debug, S, []) ->
+ loop(Parent, Debug, S);
+loop_events(
+ Parent, Debug,
+ #{callback_mode := CallbackMode,
+ module := Module,
+ state := State,
+ data := Data} = S,
+ [{Type,Content} = Event|Events] = Q) ->
+ try
+ case CallbackMode of
+ state_functions ->
+ Module:State(Type, Content, Data);
+ handle_event_function ->
+ Module:handle_event(Type, Content, State, Data)
+ end of
+ Result ->
+ loop_event_result(
+ Parent, Debug, S, Events, Event, Result)
+ catch
+ Result ->
+ loop_event_result(
+ Parent, Debug, S, Events, Event, Result);
+ error:badarg when CallbackMode =:= state_functions ->
+ case erlang:get_stacktrace() of
+ [{erlang,apply,[Module,State,_],_}|Stacktrace] ->
+ Args = [Type,Content,Data],
+ terminate(
+ error,
+ {undef_state_function,{Module,State,Args}},
+ Stacktrace,
+ Debug, S, Q);
+ Stacktrace ->
+ terminate(error, badarg, Stacktrace, Debug, S, Q)
+ end;
+ error:undef ->
+ %% Process an undef to check for the simple mistake
+ %% of calling a nonexistent state function
+ case erlang:get_stacktrace() of
+ [{Module,State,
+ [Type,Content,Data]=Args,
+ _}
+ |Stacktrace]
+ when CallbackMode =:= state_functions ->
+ terminate(
+ error,
+ {undef_state_function,{Module,State,Args}},
+ Stacktrace,
+ Debug, S, Q);
+ [{Module,handle_event,
+ [Type,Content,State,Data]=Args,
+ _}
+ |Stacktrace]
+ when CallbackMode =:= handle_event_function ->
+ terminate(
+ error,
+ {undef_state_function,
+ {Module,handle_event,Args}},
+ Stacktrace,
+ Debug, S, Q);
+ Stacktrace ->
+ terminate(error, undef, Stacktrace, Debug, S, Q)
+ end;
+ Class:Reason ->
+ Stacktrace = erlang:get_stacktrace(),
+ terminate(Class, Reason, Stacktrace, Debug, S, Q)
+ end.
+
+%% Interpret all callback return variants
+loop_event_result(
+ Parent, Debug,
+ #{state := State, data := Data} = S,
+ Events, Event, Result) ->
+ case Result of
+ stop ->
+ ?TERMINATE(exit, normal, Debug, S, [Event|Events]);
+ {stop,Reason} ->
+ ?TERMINATE(exit, Reason, Debug, S, [Event|Events]);
+ {stop,Reason,NewData} ->
+ NewS = S#{data := NewData},
+ Q = [Event|Events],
+ ?TERMINATE(exit, Reason, Debug, NewS, Q);
+ {stop_and_reply,Reason,Replies} ->
+ Q = [Event|Events],
+ [Class,NewReason,Stacktrace,NewDebug] =
+ reply_then_terminate(
+ exit, Reason, ?STACKTRACE(), Debug, S, Q, Replies),
+ %% Since we got back here Replies was bad
+ terminate(Class, NewReason, Stacktrace, NewDebug, S, Q);
+ {stop_and_reply,Reason,Replies,NewData} ->
+ NewS = S#{data := NewData},
+ Q = [Event|Events],
+ [Class,NewReason,Stacktrace,NewDebug] =
+ reply_then_terminate(
+ exit, Reason, ?STACKTRACE(), Debug, NewS, Q, Replies),
+ %% Since we got back here Replies was bad
+ terminate(Class, NewReason, Stacktrace, NewDebug, NewS, Q);
+ {next_state,NextState,NewData} ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, []);
+ {next_state,NextState,NewData,Actions} ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions);
+ {keep_state,NewData} ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, State, NewData, []);
+ {keep_state,NewData,Actions} ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, State, NewData, Actions);
+ keep_state_and_data ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, State, Data, []);
+ {keep_state_and_data,Actions} ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, State, Data, Actions);
+ _ ->
+ ?TERMINATE(
+ error, {bad_return_value,Result}, Debug, S, [Event|Events])
+ end.
+
+loop_event_actions(
+ Parent, Debug, S, Events, Event, State, NextState, NewData, Actions) ->
+ Postpone = false, % Shall we postpone this event, true or false
+ Hibernate = false,
+ Timeout = undefined,
+ NextEvents = [],
+ loop_event_actions(
+ Parent, Debug, S, Events, Event, State, NextState, NewData,
+ if
+ is_list(Actions) ->
+ Actions;
+ true ->
+ [Actions]
+ end,
+ Postpone, Hibernate, Timeout, NextEvents).
+%%
+%% Process all action()s
+loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, [Action|Actions],
+ Postpone, Hibernate, Timeout, NextEvents) ->
+ case Action of
+ %% Actual actions
+ {reply,From,Reply} ->
+ case from(From) of
+ true ->
+ NewDebug = do_reply(Debug, S, From, Reply),
+ loop_event_actions(
+ Parent, NewDebug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ Postpone, Hibernate, Timeout, NextEvents);
+ false ->
+ ?TERMINATE(
+ error, {bad_action,Action}, Debug, S, [Event|Events])
+ end;
+ {next_event,Type,Content} ->
+ case event_type(Type) of
+ true ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ Postpone, Hibernate, Timeout,
+ [{Type,Content}|NextEvents]);
+ false ->
+ ?TERMINATE(
+ error, {bad_action,Action}, Debug, S, [Event|Events])
+ end;
+ %% Actions that set options
+ {postpone,NewPostpone} when is_boolean(NewPostpone) ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ NewPostpone, Hibernate, Timeout, NextEvents);
+ {postpone,_} ->
+ ?TERMINATE(
+ error, {bad_action,Action}, Debug, S, [Event|Events]);
+ postpone ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ true, Hibernate, Timeout, NextEvents);
+ {hibernate,NewHibernate} when is_boolean(NewHibernate) ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ Postpone, NewHibernate, Timeout, NextEvents);
+ {hibernate,_} ->
+ ?TERMINATE(
+ error, {bad_action,Action}, Debug, S, [Event|Events]);
+ hibernate ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ Postpone, true, Timeout, NextEvents);
+ {timeout,infinity,_} -> % Clear timer - it will never trigger
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ Postpone, Hibernate, undefined, NextEvents);
+ {timeout,Time,_} = NewTimeout when is_integer(Time), Time >= 0 ->
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ Postpone, Hibernate, NewTimeout, NextEvents);
+ {timeout,_,_} ->
+ ?TERMINATE(
+ error, {bad_action,Action}, Debug, S, [Event|Events]);
+ infinity -> % Clear timer - it will never trigger
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ Postpone, Hibernate, undefined, NextEvents);
+ Time when is_integer(Time), Time >= 0 ->
+ NewTimeout = {timeout,Time,Time},
+ loop_event_actions(
+ Parent, Debug, S, Events, Event,
+ State, NextState, NewData, Actions,
+ Postpone, Hibernate, NewTimeout, NextEvents);
+ _ ->
+ ?TERMINATE(
+ error, {bad_action,Action}, Debug, S, [Event|Events])
+ end;
+%%
+%% End of actions list
+loop_event_actions(
+ Parent, Debug, #{postponed := P0} = S, Events, Event,
+ State, NextState, NewData, [],
+ Postpone, Hibernate, Timeout, NextEvents) ->
+ %%
+ %% All options have been collected and next_events are buffered.
+ %% Do the actual state transition.
+ %%
+ P1 = % Move current event to postponed if Postpone
+ case Postpone of
+ true ->
+ [Event|P0];
+ false ->
+ P0
+ end,
+ {Q2,P} = % Move all postponed events to queue if state change
+ if
+ NextState =:= State ->
+ {Events,P1};
+ true ->
+ {lists:reverse(P1, Events),[]}
+ end,
+ %% Place next events first in queue
+ Q3 = lists:reverse(NextEvents, Q2),
+ %%
+ NewDebug =
+ sys_debug(
+ Debug, S,
+ case Postpone of
+ true ->
+ {postpone,Event,NextState};
+ false ->
+ {consume,Event,NextState}
+ end),
+ %% Have a peek on the event queue so we can avoid starting
+ %% the state timer unless we have to
+ {Q,Timer} =
+ case Timeout of
+ undefined ->
+ %% No state timeout has been requested
+ {Q3,undefined};
+ {timeout,Time,EventContent} ->
+ %% A state timeout has been requested
+ case Q3 of
+ [] when Time =:= 0 ->
+ %% Immediate timeout - simulate it
+ %% so we do not get the timeout message
+ %% after any received event
+ {[{timeout,EventContent}],undefined};
+ [] ->
+ %% Actually start a timer
+ {Q3,erlang:start_timer(Time, self(), EventContent)};
+ _ ->
+ %% Do not start a timer since any queued
+ %% event cancels the state timer so we pretend
+ %% that the timer has been started and cancelled
+ {Q3,undefined}
+ end
+ end,
+ %% Loop to top of event queue loop; process next event
+ loop_events(
+ Parent, NewDebug,
+ S#{
+ state := NextState,
+ data := NewData,
+ timer := Timer,
+ postponed := P,
+ hibernate := Hibernate},
+ Q).
+
+%%---------------------------------------------------------------------------
+%% Server helpers
+
+reply_then_terminate(Class, Reason, Stacktrace, Debug, S, Q, Replies) ->
+ if
+ is_list(Replies) ->
+ do_reply_then_terminate(
+ Class, Reason, Stacktrace, Debug, S, Q, Replies);
+ true ->
+ do_reply_then_terminate(
+ Class, Reason, Stacktrace, Debug, S, Q, [Replies])
+ end.
+%%
+do_reply_then_terminate(Class, Reason, Stacktrace, Debug, S, Q, []) ->
+ terminate(Class, Reason, Stacktrace, Debug, S, Q);
+do_reply_then_terminate(
+ Class, Reason, Stacktrace, Debug, S, Q, [R|Rs]) ->
+ case R of
+ {reply,{_To,_Tag}=From,Reply} ->
+ NewDebug = do_reply(Debug, S, From, Reply),
+ do_reply_then_terminate(
+ Class, Reason, Stacktrace, NewDebug, S, Q, Rs);
+ _ ->
+ [error,{bad_action,R},?STACKTRACE(),Debug]
+ end.
+
+do_reply(Debug, S, From, Reply) ->
+ reply(From, Reply),
+ sys_debug(Debug, S, {out,Reply,From}).
+
+
+terminate(
+ Class, Reason, Stacktrace, Debug,
+ #{module := Module,
+ state := State, data := Data} = S,
+ Q) ->
+ try Module:terminate(Reason, State, Data) of
+ _ -> ok
+ catch
+ _ -> ok;
+ C:R ->
+ ST = erlang:get_stacktrace(),
+ error_info(
+ C, R, ST, Debug, S, Q,
+ format_status(terminate, get(), S)),
+ erlang:raise(C, R, ST)
+ end,
+ case Reason of
+ normal -> ok;
+ shutdown -> ok;
+ {shutdown,_} -> ok;
+ _ ->
+ error_info(
+ Class, Reason, Stacktrace, Debug, S, Q,
+ format_status(terminate, get(), S))
+ end,
+ case Stacktrace of
+ [] ->
+ erlang:Class(Reason);
+ _ ->
+ erlang:raise(Class, Reason, Stacktrace)
+ end.
+
+error_info(
+ Class, Reason, Stacktrace, Debug,
+ #{name := Name, callback_mode := CallbackMode,
+ state := State, postponed := P},
+ Q, FmtData) ->
+ {FixedReason,FixedStacktrace} =
+ case Stacktrace of
+ [{M,F,Args,_}|ST]
+ when Class =:= error, Reason =:= undef ->
+ case code:is_loaded(M) of
+ false ->
+ {{'module could not be loaded',M},ST};
+ _ ->
+ Arity =
+ if
+ is_list(Args) ->
+ length(Args);
+ is_integer(Args) ->
+ Args
+ end,
+ case erlang:function_exported(M, F, Arity) of
+ true ->
+ {Reason,Stacktrace};
+ false ->
+ {{'function not exported',{M,F,Arity}},
+ ST}
+ end
+ end;
+ _ -> {Reason,Stacktrace}
+ end,
+ error_logger:format(
+ "** State machine ~p terminating~n" ++
+ case Q of
+ [] ->
+ "";
+ _ ->
+ "** Last event = ~p~n"
+ end ++
+ "** When Server state = ~p~n" ++
+ "** Reason for termination = ~w:~p~n" ++
+ "** State = ~p~n" ++
+ "** Callback mode = ~p~n" ++
+ "** Queued/Postponed = ~w/~w~n" ++
+ case FixedStacktrace of
+ [] ->
+ "";
+ _ ->
+ "** Stacktrace =~n"
+ "** ~p~n"
+ end,
+ [Name |
+ case Q of
+ [] ->
+ [];
+ [Event|_] ->
+ [Event]
+ end] ++
+ [FmtData,Class,FixedReason,
+ State,CallbackMode,length(Q),length(P)] ++
+ case FixedStacktrace of
+ [] ->
+ [];
+ _ ->
+ [FixedStacktrace]
+ end),
+ sys:print_log(Debug),
+ ok.
+
+
+%% Call Module:format_status/2 or return a default value
+format_status(
+ Opt, PDict,
+ #{module := Module, state := State, data := Data}) ->
+ case erlang:function_exported(Module, format_status, 2) of
+ true ->
+ try Module:format_status(Opt, [PDict,State,Data])
+ catch
+ Result -> Result;
+ _:_ ->
+ format_status_default(
+ Opt, State,
+ "Module:format_status/2 crashed")
+ end;
+ false ->
+ format_status_default(Opt, State, Data)
+ end.
+
+%% The default Module:format_status/2
+format_status_default(Opt, State, Data) ->
+ SSD = {State,Data},
+ case Opt of
+ terminate ->
+ SSD;
+ _ ->
+ [{data,[{"State",SSD}]}]
+ end.
diff --git a/lib/stdlib/src/proc_lib.erl b/lib/stdlib/src/proc_lib.erl
index c47d30c8b8..3f79ed0f87 100644
--- a/lib/stdlib/src/proc_lib.erl
+++ b/lib/stdlib/src/proc_lib.erl
@@ -472,13 +472,15 @@ trans_init(gen,init_it,[gen_server,_,_,supervisor_bridge,[Module|_],_]) ->
{supervisor_bridge,Module,1};
trans_init(gen,init_it,[gen_server,_,_,_,supervisor_bridge,[Module|_],_]) ->
{supervisor_bridge,Module,1};
-trans_init(gen,init_it,[gen_server,_,_,Module,_,_]) ->
+trans_init(gen,init_it,[GenMod,_,_,Module,_,_])
+ when GenMod =:= gen_server;
+ GenMod =:= gen_statem;
+ GenMod =:= gen_fsm ->
{Module,init,1};
-trans_init(gen,init_it,[gen_server,_,_,_,Module|_]) ->
- {Module,init,1};
-trans_init(gen,init_it,[gen_fsm,_,_,Module,_,_]) ->
- {Module,init,1};
-trans_init(gen,init_it,[gen_fsm,_,_,_,Module|_]) ->
+trans_init(gen,init_it,[GenMod,_,_,_,Module|_])
+ when GenMod =:= gen_server;
+ GenMod =:= gen_statem;
+ GenMod =:= gen_fsm ->
{Module,init,1};
trans_init(gen,init_it,[gen_event|_]) ->
{gen_event,init_it,6};
diff --git a/lib/stdlib/src/stdlib.app.src b/lib/stdlib/src/stdlib.app.src
index e3950ee795..32bcdc4f2a 100644
--- a/lib/stdlib/src/stdlib.app.src
+++ b/lib/stdlib/src/stdlib.app.src
@@ -65,6 +65,7 @@
gen_event,
gen_fsm,
gen_server,
+ gen_statem,
io,
io_lib,
io_lib_format,
diff --git a/lib/stdlib/test/Makefile b/lib/stdlib/test/Makefile
index 287f63b2be..28c35aed55 100644
--- a/lib/stdlib/test/Makefile
+++ b/lib/stdlib/test/Makefile
@@ -46,6 +46,7 @@ MODULES= \
gen_event_SUITE \
gen_fsm_SUITE \
gen_server_SUITE \
+ gen_statem_SUITE \
id_transform_SUITE \
io_SUITE \
io_proto_SUITE \
diff --git a/lib/stdlib/test/error_logger_forwarder.erl b/lib/stdlib/test/error_logger_forwarder.erl
index 0aecd41ba9..6bbf180585 100644
--- a/lib/stdlib/test/error_logger_forwarder.erl
+++ b/lib/stdlib/test/error_logger_forwarder.erl
@@ -20,7 +20,7 @@
-module(error_logger_forwarder).
%% API.
--export([register/0]).
+-export([register/0, unregister/0]).
%% Internal export for error_logger.
-export([init/1,
@@ -33,6 +33,10 @@
register() ->
error_logger:add_report_handler(?MODULE, self()).
+unregister() ->
+ Self = self(),
+ Self = error_logger:delete_report_handler(?MODULE).
+
init(Tester) ->
{ok,Tester}.
diff --git a/lib/stdlib/test/gen_statem_SUITE.erl b/lib/stdlib/test/gen_statem_SUITE.erl
new file mode 100644
index 0000000000..3deb5fd986
--- /dev/null
+++ b/lib/stdlib/test/gen_statem_SUITE.erl
@@ -0,0 +1,1578 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2016. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(gen_statem_SUITE).
+
+-include_lib("common_test/include/ct.hrl").
+
+-compile(export_all).
+-behaviour(gen_statem).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+suite() ->
+ [{ct_hooks,[ts_install_cth]},
+ {timetrap,{minutes,1}}].
+
+all() ->
+ [{group, start},
+ {group, start_handle_event},
+ {group, stop},
+ {group, stop_handle_event},
+ {group, abnormal},
+ {group, abnormal_handle_event},
+ shutdown, stop_and_reply, event_order,
+ {group, sys},
+ hibernate, enter_loop].
+
+groups() ->
+ [{start, [],
+ [start1, start2, start3, start4, start5, start6, start7,
+ start8, start9, start10, start11, start12, next_events]},
+ {start_handle_event, [],
+ [start1, start2, start3, start4, start5, start6, start7,
+ start8, start9, start10, start11, start12, next_events]},
+ {stop, [],
+ [stop1, stop2, stop3, stop4, stop5, stop6, stop7, stop8, stop9, stop10]},
+ {stop_handle_event, [],
+ [stop1, stop2, stop3, stop4, stop5, stop6, stop7, stop8, stop9, stop10]},
+ {abnormal, [], [abnormal1, abnormal2]},
+ {abnormal_handle_event, [], [abnormal1, abnormal2]},
+ {sys, [],
+ [sys1, code_change,
+ call_format_status,
+ error_format_status, terminate_crash_format,
+ get_state, replace_state]},
+ {sys_handle_event, [],
+ [sys1,
+ call_format_status,
+ error_format_status, terminate_crash_format,
+ get_state, replace_state]}].
+
+init_per_suite(Config) ->
+ Config.
+
+end_per_suite(_Config) ->
+ ok.
+
+init_per_group(GroupName, Config)
+ when GroupName =:= start_handle_event;
+ GroupName =:= stop_handle_event;
+ GroupName =:= abnormal_handle_event;
+ GroupName =:= sys_handle_event ->
+ [{callback_mode,handle_event_function}|Config];
+init_per_group(_GroupName, Config) ->
+ Config.
+
+end_per_group(_GroupName, Config) ->
+ Config.
+
+init_per_testcase(_CaseName, Config) ->
+ flush(),
+%%% dbg:tracer(),
+%%% dbg:p(all, c),
+%%% dbg:tpl(gen_statem, cx),
+%%% dbg:tpl(proc_lib, cx),
+%%% dbg:tpl(gen, cx),
+%%% dbg:tpl(sys, cx),
+ Config.
+
+end_per_testcase(_CaseName, Config) ->
+%%% dbg:stop(),
+ Config.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+-define(EXPECT_FAILURE(Code, Reason),
+ try begin Code end of
+ Reason ->
+ ct:fail({unexpected,Reason})
+ catch
+ error:Reason -> Reason;
+ exit:Reason -> Reason
+ end).
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%% anonymous
+start1(Config) ->
+ %%OldFl = process_flag(trap_exit, true),
+
+ {ok,Pid0} = gen_statem:start_link(?MODULE, start_arg(Config, []), []),
+ ok = do_func_test(Pid0),
+ ok = do_sync_func_test(Pid0),
+ stop_it(Pid0),
+%% stopped = gen_statem:call(Pid0, stop),
+%% timeout =
+%% ?EXPECT_FAILURE(gen_statem:call(Pid0, hej), Reason),
+
+ %%process_flag(trap_exit, OldFl),
+ ok = verify_empty_msgq().
+
+%% anonymous w. shutdown
+start2(Config) ->
+ %% Dont link when shutdown
+ {ok,Pid0} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+ ok = do_func_test(Pid0),
+ ok = do_sync_func_test(Pid0),
+ stopped = gen_statem:call(Pid0, {stop,shutdown}),
+ check_stopped(Pid0),
+ ok = verify_empty_msgq().
+
+%% anonymous with timeout
+start3(Config) ->
+ %%OldFl = process_flag(trap_exit, true),
+
+ {ok,Pid0} =
+ gen_statem:start(?MODULE, start_arg(Config, []), [{timeout,5}]),
+ ok = do_func_test(Pid0),
+ ok = do_sync_func_test(Pid0),
+ stop_it(Pid0),
+
+ {error,timeout} =
+ gen_statem:start(
+ ?MODULE, start_arg(Config, sleep), [{timeout,5}]),
+
+ %%process_flag(trap_exit, OldFl),
+ ok = verify_empty_msgq().
+
+%% anonymous with ignore
+start4(Config) ->
+ OldFl = process_flag(trap_exit, true),
+
+ ignore = gen_statem:start(?MODULE, start_arg(Config, ignore), []),
+
+ process_flag(trap_exit, OldFl),
+ ok = verify_empty_msgq().
+
+%% anonymous with stop
+start5(Config) ->
+ OldFl = process_flag(trap_exit, true),
+
+ {error,stopped} = gen_statem:start(?MODULE, start_arg(Config, stop), []),
+
+ process_flag(trap_exit, OldFl),
+ ok = verify_empty_msgq().
+
+%% anonymous linked
+start6(Config) ->
+ {ok,Pid} = gen_statem:start_link(?MODULE, start_arg(Config, []), []),
+ ok = do_func_test(Pid),
+ ok = do_sync_func_test(Pid),
+ stop_it(Pid),
+
+ ok = verify_empty_msgq().
+
+%% global register linked
+start7(Config) ->
+ STM = {global,my_stm},
+
+ {ok,Pid} =
+ gen_statem:start_link(STM, ?MODULE, start_arg(Config, []), []),
+ {error,{already_started,Pid}} =
+ gen_statem:start_link(STM, ?MODULE, start_arg(Config, []), []),
+ {error,{already_started,Pid}} =
+ gen_statem:start(STM, ?MODULE, start_arg(Config, []), []),
+
+ ok = do_func_test(Pid),
+ ok = do_sync_func_test(Pid),
+ ok = do_func_test(STM),
+ ok = do_sync_func_test(STM),
+ stop_it(STM),
+
+ ok = verify_empty_msgq().
+
+
+%% local register
+start8(Config) ->
+ %%OldFl = process_flag(trap_exit, true),
+ Name = my_stm,
+ STM = {local,Name},
+
+ {ok,Pid} =
+ gen_statem:start(STM, ?MODULE, start_arg(Config, []), []),
+ {error,{already_started,Pid}} =
+ gen_statem:start(STM, ?MODULE, start_arg(Config, []), []),
+
+ ok = do_func_test(Pid),
+ ok = do_sync_func_test(Pid),
+ ok = do_func_test(Name),
+ ok = do_sync_func_test(Name),
+ stop_it(Pid),
+
+ %%process_flag(trap_exit, OldFl),
+ ok = verify_empty_msgq().
+
+%% local register linked
+start9(Config) ->
+ %%OldFl = process_flag(trap_exit, true),
+ Name = my_stm,
+ STM = {local,Name},
+
+ {ok,Pid} =
+ gen_statem:start_link(STM, ?MODULE, start_arg(Config, []), []),
+ {error,{already_started,Pid}} =
+ gen_statem:start(STM, ?MODULE, start_arg(Config, []), []),
+
+ ok = do_func_test(Pid),
+ ok = do_sync_func_test(Pid),
+ ok = do_func_test(Name),
+ ok = do_sync_func_test(Name),
+ stop_it(Pid),
+
+ %%process_flag(trap_exit, OldFl),
+ ok = verify_empty_msgq().
+
+%% global register
+start10(Config) ->
+ STM = {global,my_stm},
+
+ {ok,Pid} =
+ gen_statem:start(STM, ?MODULE, start_arg(Config, []), []),
+ {error,{already_started,Pid}} =
+ gen_statem:start(STM, ?MODULE, start_arg(Config, []), []),
+ {error,{already_started,Pid}} =
+ gen_statem:start_link(STM, ?MODULE, start_arg(Config, []), []),
+
+ ok = do_func_test(Pid),
+ ok = do_sync_func_test(Pid),
+ ok = do_func_test(STM),
+ ok = do_sync_func_test(STM),
+ stop_it(STM),
+
+ ok = verify_empty_msgq().
+
+%% Stop registered processes
+start11(Config) ->
+ Name = my_stm,
+ LocalSTM = {local,Name},
+ GlobalSTM = {global,Name},
+
+ {ok,Pid} =
+ gen_statem:start_link(LocalSTM, ?MODULE, start_arg(Config, []), []),
+ stop_it(Pid),
+
+ {ok,_Pid1} =
+ gen_statem:start_link(LocalSTM, ?MODULE, start_arg(Config, []), []),
+ stop_it(Name),
+
+ {ok,Pid2} =
+ gen_statem:start(GlobalSTM, ?MODULE, start_arg(Config, []), []),
+ stop_it(Pid2),
+ receive after 1 -> true end,
+ Result =
+ gen_statem:start(GlobalSTM, ?MODULE, start_arg(Config, []), []),
+ ct:log("Result = ~p~n",[Result]),
+ {ok,_Pid3} = Result,
+ stop_it(GlobalSTM),
+
+ ok = verify_empty_msgq().
+
+%% Via register linked
+start12(Config) ->
+ dummy_via:reset(),
+ VIA = {via,dummy_via,my_stm},
+
+ {ok,Pid} =
+ gen_statem:start_link(VIA, ?MODULE, start_arg(Config, []), []),
+ {error,{already_started,Pid}} =
+ gen_statem:start_link(VIA, ?MODULE, start_arg(Config, []), []),
+ {error,{already_started,Pid}} =
+ gen_statem:start(VIA, ?MODULE, start_arg(Config, []), []),
+
+ ok = do_func_test(Pid),
+ ok = do_sync_func_test(Pid),
+ ok = do_func_test(VIA),
+ ok = do_sync_func_test(VIA),
+ stop_it(VIA),
+
+ ok = verify_empty_msgq().
+
+
+%% Anonymous, reason 'normal'
+stop1(Config) ->
+ {ok,Pid} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+ ok = gen_statem:stop(Pid),
+ false = erlang:is_process_alive(Pid),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(Pid), Reason).
+
+%% Anonymous, other reason
+stop2(Config) ->
+ {ok,Pid} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+ ok = gen_statem:stop(Pid, other_reason, infinity),
+ false = erlang:is_process_alive(Pid),
+ ok.
+
+%% Anonymous, invalid timeout
+stop3(Config) ->
+ {ok,Pid} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+ _ =
+ ?EXPECT_FAILURE(
+ gen_statem:stop(Pid, other_reason, invalid_timeout),
+ Reason),
+ true = erlang:is_process_alive(Pid),
+ ok = gen_statem:stop(Pid),
+ false = erlang:is_process_alive(Pid),
+ ok.
+
+%% Registered name
+stop4(Config) ->
+ {ok,Pid} =
+ gen_statem:start(
+ {local,to_stop},?MODULE, start_arg(Config, []), []),
+ ok = gen_statem:stop(to_stop),
+ false = erlang:is_process_alive(Pid),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(to_stop), Reason),
+ ok.
+
+%% Registered name and local node
+stop5(Config) ->
+ Name = to_stop,
+ {ok,Pid} =
+ gen_statem:start(
+ {local,Name},?MODULE, start_arg(Config, []), []),
+ ok = gen_statem:stop({Name,node()}),
+ false = erlang:is_process_alive(Pid),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop({Name,node()}), Reason),
+ ok.
+
+%% Globally registered name
+stop6(Config) ->
+ STM = {global,to_stop},
+ {ok,Pid} = gen_statem:start(STM, ?MODULE, start_arg(Config, []), []),
+ ok = gen_statem:stop(STM),
+ false = erlang:is_process_alive(Pid),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(STM), Reason),
+ ok.
+
+%% 'via' registered name
+stop7(Config) ->
+ VIA = {via,dummy_via,to_stop},
+ dummy_via:reset(),
+ {ok,Pid} = gen_statem:start(VIA, ?MODULE, start_arg(Config, []), []),
+ ok = gen_statem:stop(VIA),
+ false = erlang:is_process_alive(Pid),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(VIA), Reason),
+ ok.
+
+%% Anonymous on remote node
+stop8(Config) ->
+ Node = gen_statem_stop8,
+ {ok,NodeName} = ct_slave:start(Node),
+ Dir = filename:dirname(code:which(?MODULE)),
+ rpc:call(NodeName, code, add_path, [Dir]),
+ {ok,Pid} =
+ rpc:call(
+ NodeName, gen_statem,start,
+ [?MODULE,start_arg(Config, []),[]]),
+ ok = gen_statem:stop(Pid),
+ false = rpc:call(NodeName, erlang, is_process_alive, [Pid]),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(Pid), Reason1),
+ {ok,NodeName} = ct_slave:stop(Node),
+ {{nodedown,NodeName},{sys,terminate,_}} =
+ ?EXPECT_FAILURE(gen_statem:stop(Pid), Reason2),
+ ok.
+
+%% Registered name on remote node
+stop9(Config) ->
+ Name = to_stop,
+ LocalSTM = {local,Name},
+ Node = gen_statem__stop9,
+ {ok,NodeName} = ct_slave:start(Node),
+ STM = {Name,NodeName},
+ Dir = filename:dirname(code:which(?MODULE)),
+ rpc:call(NodeName, code, add_path, [Dir]),
+ {ok,Pid} =
+ rpc:call(
+ NodeName, gen_statem, start,
+ [LocalSTM,?MODULE,start_arg(Config, []),[]]),
+ ok = gen_statem:stop(STM),
+ undefined = rpc:call(NodeName,erlang,whereis,[Name]),
+ false = rpc:call(NodeName,erlang,is_process_alive,[Pid]),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(STM), Reason1),
+ {ok,NodeName} = ct_slave:stop(Node),
+ {{nodedown,NodeName},{sys,terminate,_}} =
+ ?EXPECT_FAILURE(gen_statem:stop(STM), Reason2),
+ ok.
+
+%% Globally registered name on remote node
+stop10(Config) ->
+ Node = gen_statem_stop10,
+ STM = {global,to_stop},
+ {ok,NodeName} = ct_slave:start(Node),
+ Dir = filename:dirname(code:which(?MODULE)),
+ rpc:call(NodeName,code,add_path,[Dir]),
+ {ok,Pid} =
+ rpc:call(
+ NodeName, gen_statem, start,
+ [STM,?MODULE,start_arg(Config, []),[]]),
+ global:sync(),
+ ok = gen_statem:stop(STM),
+ false = rpc:call(NodeName, erlang, is_process_alive, [Pid]),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(STM), Reason1),
+ {ok,NodeName} = ct_slave:stop(Node),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(STM), Reason2),
+ ok.
+
+%% Check that time outs in calls work
+abnormal1(Config) ->
+ Name = abnormal1,
+ LocalSTM = {local,Name},
+
+ {ok, _Pid} =
+ gen_statem:start(LocalSTM, ?MODULE, start_arg(Config, []), []),
+
+ %% timeout call.
+ delayed = gen_statem:call(Name, {delayed_answer,1}, 100),
+ {timeout,_} =
+ ?EXPECT_FAILURE(
+ gen_statem:call(Name, {delayed_answer,1000}, 10),
+ Reason),
+ ok = gen_statem:stop(Name),
+ ok = verify_empty_msgq().
+
+%% Check that bad return values makes the stm crash. Note that we must
+%% trap exit since we must link to get the real bad_return_ error
+abnormal2(Config) ->
+ OldFl = process_flag(trap_exit, true),
+ {ok,Pid} = gen_statem:start_link(?MODULE, start_arg(Config, []), []),
+
+ %% bad return value in the gen_statem loop
+ {{bad_return_value,badreturn},_} =
+ ?EXPECT_FAILURE(gen_statem:call(Pid, badreturn), Reason),
+ receive
+ {'EXIT',Pid,{bad_return_value,badreturn}} -> ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ process_flag(trap_exit, OldFl),
+ ok = verify_empty_msgq().
+
+shutdown(Config) ->
+ process_flag(trap_exit, true),
+
+ {ok,Pid0} = gen_statem:start_link(?MODULE, start_arg(Config, []), []),
+ ok = do_func_test(Pid0),
+ ok = do_sync_func_test(Pid0),
+ stopped = gen_statem:call(Pid0, {stop,{shutdown,reason}}),
+ receive {'EXIT',Pid0,{shutdown,reason}} -> ok end,
+ process_flag(trap_exit, false),
+
+ {noproc,_} =
+ ?EXPECT_FAILURE(gen_statem:call(Pid0, hej), Reason),
+
+ receive
+ Any ->
+ ct:log("Unexpected: ~p", [Any]),
+ ct:fail({unexpected,Any})
+ after 500 ->
+ ok
+ end.
+
+
+
+stop_and_reply(_Config) ->
+ process_flag(trap_exit, true),
+
+ Machine =
+ %% Abusing the internal format of From...
+ #{init =>
+ fun () ->
+ {ok,start,undefined}
+ end,
+ start =>
+ fun (cast, {echo,From1,Reply1}, undefined) ->
+ {next_state,wait,{reply,From1,Reply1}}
+ end,
+ wait =>
+ fun (cast, {stop_and_reply,Reason,From2,Reply2},R1) ->
+ {stop_and_reply,Reason,
+ [R1,{reply,From2,Reply2}]}
+ end},
+ {ok,STM} = gen_statem:start_link(?MODULE, {map_statem,Machine}, []),
+
+ Self = self(),
+ Tag1 = make_ref(),
+ gen_statem:cast(STM, {echo,{Self,Tag1},reply1}),
+ Tag2 = make_ref(),
+ gen_statem:cast(STM, {stop_and_reply,reason,{Self,Tag2},reply2}),
+ case flush() of
+ [{Tag1,reply1},{Tag2,reply2},{'EXIT',STM,reason}] ->
+ ok;
+ Other1 ->
+ ct:fail({unexpected,Other1})
+ end,
+
+ {noproc,_} =
+ ?EXPECT_FAILURE(gen_statem:call(STM, hej), Reason),
+ case flush() of
+ [] ->
+ ok;
+ Other2 ->
+ ct:fail({unexpected,Other2})
+ end.
+
+
+
+event_order(_Config) ->
+ process_flag(trap_exit, true),
+
+ Machine =
+ %% Abusing the internal format of From...
+ #{init =>
+ fun () ->
+ {ok,start,undefined}
+ end,
+ start =>
+ fun (cast, _, _) ->
+ {keep_state_and_data,postpone}; %% Handled in 'buffer'
+ ({call,From}, {buffer,Pid,[Tag3,Tag4,Tag5]},
+ undefined) ->
+ {next_state,buffer,[],
+ [{next_event,internal,{reply,{Pid,Tag3},ok3}},
+ {next_event,internal,{reply,{Pid,Tag4},ok4}},
+ {timeout,0,{reply,{Pid,Tag5},ok5}},
+ %% The timeout should not happen since there
+ %% are events that cancel it i.e next_event
+ %% and postponed
+ {reply,From,ok}]}
+ end,
+ buffer =>
+ fun (internal, Reply, Replies) ->
+ {keep_state,[Reply|Replies]};
+ (timeout, Reply, Replies) ->
+ {keep_state,[Reply|Replies]};
+ (cast, Reply, Replies) ->
+ {keep_state,[Reply|Replies]};
+ ({call,From}, {stop,Reason}, Replies) ->
+ {next_state,stop,undefined,
+ lists:reverse(
+ Replies,
+ [{reply,From,ok},
+ {next_event,internal,{stop,Reason}}])}
+ end,
+ stop =>
+ fun (internal, Result, undefined) ->
+ Result
+ end},
+
+ {ok,STM} = gen_statem:start_link(?MODULE, {map_statem,Machine}, []),
+ Self = self(),
+ Tag1 = make_ref(),
+ gen_statem:cast(STM, {reply,{Self,Tag1},ok1}),
+ Tag2 = make_ref(),
+ gen_statem:cast(STM, {reply,{Self,Tag2},ok2}),
+ Tag3 = make_ref(),
+ Tag4 = make_ref(),
+ Tag5 = make_ref(),
+ ok = gen_statem:call(STM, {buffer,Self,[Tag3,Tag4,Tag5]}),
+ ok = gen_statem:call(STM, {stop,reason}),
+ case flush() of
+ [{Tag3,ok3},{Tag4,ok4},{Tag1,ok1},{Tag2,ok2},
+ {'EXIT',STM,reason}] ->
+ ok;
+ Other1 ->
+ ct:fail({unexpected,Other1})
+ end,
+
+ {noproc,_} =
+ ?EXPECT_FAILURE(gen_statem:call(STM, hej), Reason),
+ case flush() of
+ [] ->
+ ok;
+ Other2 ->
+ ct:fail({unexpected,Other2})
+ end.
+
+
+
+sys1(Config) ->
+ {ok,Pid} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+ {status, Pid, {module,gen_statem}, _} = sys:get_status(Pid),
+ sys:suspend(Pid),
+ Parent = self(),
+ Tag = make_ref(),
+ Caller =
+ spawn(
+ fun () ->
+ Parent ! {Tag,gen_statem:call(Pid, hej)}
+ end),
+ receive
+ {Tag,_} ->
+ ct:fail(should_be_suspended)
+ after 3000 ->
+ exit(Caller, ok)
+ end,
+
+ %% {timeout,_} =
+ %% ?EXPECT_FAILURE(gen_statem:call(Pid, hej), Reason),
+ sys:resume(Pid),
+ stop_it(Pid).
+
+code_change(Config) ->
+ {ok,Pid} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+ {idle,data} = sys:get_state(Pid),
+ sys:suspend(Pid),
+ sys:change_code(Pid, ?MODULE, old_vsn, state_functions),
+ sys:resume(Pid),
+ {idle,{old_vsn,data,state_functions}} = sys:get_state(Pid),
+ stop_it(Pid).
+
+call_format_status(Config) ->
+ {ok,Pid} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+ Status = sys:get_status(Pid),
+ {status,Pid,_Mod,[_PDict,running,_,_, Data]} = Status,
+ [format_status_called|_] = lists:reverse(Data),
+ stop_it(Pid),
+
+ %% check that format_status can handle a name being an atom (pid is
+ %% already checked by the previous test)
+ {ok, Pid2} =
+ gen_statem:start(
+ {local, gstm}, ?MODULE, start_arg(Config, []), []),
+ Status2 = sys:get_status(gstm),
+ {status,Pid2,_Mod,[_PDict2,running,_,_,Data2]} = Status2,
+ [format_status_called|_] = lists:reverse(Data2),
+ stop_it(Pid2),
+
+ %% check that format_status can handle a name being a term other than a
+ %% pid or atom
+ GlobalName1 = {global,"CallFormatStatus"},
+ {ok,Pid3} =
+ gen_statem:start(
+ GlobalName1, ?MODULE, start_arg(Config, []), []),
+ Status3 = sys:get_status(GlobalName1),
+ {status,Pid3,_Mod,[_PDict3,running,_,_,Data3]} = Status3,
+ [format_status_called|_] = lists:reverse(Data3),
+ stop_it(Pid3),
+ GlobalName2 = {global,{name, "term"}},
+ {ok,Pid4} =
+ gen_statem:start(
+ GlobalName2, ?MODULE, start_arg(Config, []), []),
+ Status4 = sys:get_status(GlobalName2),
+ {status,Pid4,_Mod,[_PDict4,running,_,_, Data4]} = Status4,
+ [format_status_called|_] = lists:reverse(Data4),
+ stop_it(Pid4),
+
+ %% check that format_status can handle a name being a term other than a
+ %% pid or atom
+ dummy_via:reset(),
+ ViaName1 = {via,dummy_via,"CallFormatStatus"},
+ {ok,Pid5} = gen_statem:start(ViaName1, ?MODULE, start_arg(Config, []), []),
+ Status5 = sys:get_status(ViaName1),
+ {status,Pid5,_Mod, [_PDict5,running,_,_, Data5]} = Status5,
+ [format_status_called|_] = lists:reverse(Data5),
+ stop_it(Pid5),
+ ViaName2 = {via,dummy_via,{name,"term"}},
+ {ok, Pid6} =
+ gen_statem:start(
+ ViaName2, ?MODULE, start_arg(Config, []), []),
+ Status6 = sys:get_status(ViaName2),
+ {status,Pid6,_Mod,[_PDict6,running,_,_,Data6]} = Status6,
+ [format_status_called|_] = lists:reverse(Data6),
+ stop_it(Pid6).
+
+
+
+error_format_status(Config) ->
+ error_logger_forwarder:register(),
+ OldFl = process_flag(trap_exit, true),
+ Data = "called format_status",
+ {ok,Pid} =
+ gen_statem:start(
+ ?MODULE, start_arg(Config, {data,Data}), []),
+ %% bad return value in the gen_statem loop
+ {{bad_return_value,badreturn},_} =
+ ?EXPECT_FAILURE(gen_statem:call(Pid, badreturn), Reason),
+ receive
+ {error,_,
+ {Pid,
+ "** State machine"++_,
+ [Pid,{{call,_},badreturn},
+ {formatted,idle,Data},
+ error,{bad_return_value,badreturn}|_]}} ->
+ ok;
+ Other when is_tuple(Other), element(1, Other) =:= error ->
+ error_logger_forwarder:unregister(),
+ ct:fail({unexpected,Other})
+ after 1000 ->
+ error_logger_forwarder:unregister(),
+ ct:fail(timeout)
+ end,
+ process_flag(trap_exit, OldFl),
+ error_logger_forwarder:unregister(),
+ receive
+ %% Comes with SASL
+ {error_report,_,{Pid,crash_report,_}} ->
+ ok
+ after 500 ->
+ ok
+ end,
+ ok = verify_empty_msgq().
+
+terminate_crash_format(Config) ->
+ error_logger_forwarder:register(),
+ OldFl = process_flag(trap_exit, true),
+ Data = crash_terminate,
+ {ok,Pid} =
+ gen_statem:start(
+ ?MODULE, start_arg(Config, {data,Data}), []),
+ stop_it(Pid),
+ Self = self(),
+ receive
+ {error,_GroupLeader,
+ {Pid,
+ "** State machine"++_,
+ [Pid,
+ {{call,{Self,_}},stop},
+ {formatted,idle,Data},
+ exit,{crash,terminate}|_]}} ->
+ ok;
+ Other when is_tuple(Other), element(1, Other) =:= error ->
+ error_logger_forwarder:unregister(),
+ ct:fail({unexpected,Other})
+ after 1000 ->
+ error_logger_forwarder:unregister(),
+ ct:fail(timeout)
+ end,
+ process_flag(trap_exit, OldFl),
+ error_logger_forwarder:unregister(),
+ receive
+ %% Comes with SASL
+ {error_report,_,{Pid,crash_report,_}} ->
+ ok
+ after 500 ->
+ ok
+ end,
+ ok = verify_empty_msgq().
+
+
+get_state(Config) ->
+ State = self(),
+ {ok,Pid} =
+ gen_statem:start(
+ ?MODULE, start_arg(Config, {data,State}), []),
+ {idle,State} = sys:get_state(Pid),
+ {idle,State} = sys:get_state(Pid, 5000),
+ stop_it(Pid),
+
+ %% check that get_state can handle a name being an atom (pid is
+ %% already checked by the previous test)
+ {ok,Pid2} =
+ gen_statem:start(
+ {local,gstm}, ?MODULE, start_arg(Config, {data,State}), []),
+ {idle,State} = sys:get_state(gstm),
+ {idle,State} = sys:get_state(gstm, 5000),
+ stop_it(Pid2),
+
+ %% check that get_state works when pid is sys suspended
+ {ok,Pid3} =
+ gen_statem:start(
+ ?MODULE, start_arg(Config, {data,State}), []),
+ {idle,State} = sys:get_state(Pid3),
+ ok = sys:suspend(Pid3),
+ {idle,State} = sys:get_state(Pid3, 5000),
+ ok = sys:resume(Pid3),
+ stop_it(Pid3),
+ ok = verify_empty_msgq().
+
+replace_state(Config) ->
+ State = self(),
+ {ok, Pid} =
+ gen_statem:start(
+ ?MODULE, start_arg(Config, {data,State}), []),
+ {idle,State} = sys:get_state(Pid),
+ NState1 = "replaced",
+ Replace1 = fun({StateName, _}) -> {StateName,NState1} end,
+ {idle,NState1} = sys:replace_state(Pid, Replace1),
+ {idle,NState1} = sys:get_state(Pid),
+ NState2 = "replaced again",
+ Replace2 = fun({idle, _}) -> {state0,NState2} end,
+ {state0,NState2} = sys:replace_state(Pid, Replace2, 5000),
+ {state0,NState2} = sys:get_state(Pid),
+ %% verify no change in state if replace function crashes
+ Replace3 = fun(_) -> error(fail) end,
+ {callback_failed,
+ {gen_statem,system_replace_state},{error,fail}} =
+ ?EXPECT_FAILURE(sys:replace_state(Pid, Replace3), Reason),
+ {state0, NState2} = sys:get_state(Pid),
+ %% verify state replaced if process sys suspended
+ ok = sys:suspend(Pid),
+ Suffix2 = " and again",
+ NState3 = NState2 ++ Suffix2,
+ Replace4 = fun({StateName, _}) -> {StateName, NState3} end,
+ {state0,NState3} = sys:replace_state(Pid, Replace4),
+ ok = sys:resume(Pid),
+ {state0,NState3} = sys:get_state(Pid, 5000),
+ stop_it(Pid),
+ ok = verify_empty_msgq().
+
+%% Hibernation
+hibernate(Config) ->
+ OldFl = process_flag(trap_exit, true),
+
+ {ok,Pid0} =
+ gen_statem:start_link(
+ ?MODULE, start_arg(Config, hiber_now), []),
+ is_in_erlang_hibernate(Pid0),
+ stop_it(Pid0),
+ receive
+ {'EXIT',Pid0,normal} -> ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ {ok,Pid} =
+ gen_statem:start_link(?MODULE, start_arg(Config, hiber), []),
+ true = ({current_function,{erlang,hibernate,3}} =/=
+ erlang:process_info(Pid,current_function)),
+ hibernating = gen_statem:call(Pid, hibernate_sync),
+ is_in_erlang_hibernate(Pid),
+ good_morning = gen_statem:call(Pid, wakeup_sync),
+ is_not_in_erlang_hibernate(Pid),
+ hibernating = gen_statem:call(Pid, hibernate_sync),
+ is_in_erlang_hibernate(Pid),
+ please_just_five_more = gen_statem:call(Pid, snooze_sync),
+ is_in_erlang_hibernate(Pid),
+ good_morning = gen_statem:call(Pid, wakeup_sync),
+ is_not_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, hibernate_async),
+ is_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, wakeup_async),
+ is_not_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, hibernate_async),
+ is_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, snooze_async),
+ is_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, wakeup_async),
+ is_not_in_erlang_hibernate(Pid),
+
+ Pid ! hibernate_later,
+ true =
+ ({current_function,{erlang,hibernate,3}} =/=
+ erlang:process_info(Pid, current_function)),
+ is_in_erlang_hibernate(Pid),
+
+ 'alive!' = gen_statem:call(Pid, 'alive?'),
+ true =
+ ({current_function,{erlang,hibernate,3}} =/=
+ erlang:process_info(Pid, current_function)),
+ Pid ! hibernate_now,
+ is_in_erlang_hibernate(Pid),
+
+ 'alive!' = gen_statem:call(Pid, 'alive?'),
+ true =
+ ({current_function,{erlang,hibernate,3}} =/=
+ erlang:process_info(Pid, current_function)),
+
+ hibernating = gen_statem:call(Pid, hibernate_sync),
+ is_in_erlang_hibernate(Pid),
+ good_morning = gen_statem:call(Pid, wakeup_sync),
+ is_not_in_erlang_hibernate(Pid),
+ hibernating = gen_statem:call(Pid, hibernate_sync),
+ is_in_erlang_hibernate(Pid),
+ please_just_five_more = gen_statem:call(Pid, snooze_sync),
+ is_in_erlang_hibernate(Pid),
+ good_morning = gen_statem:call(Pid, wakeup_sync),
+ is_not_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, hibernate_async),
+ is_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, wakeup_async),
+ is_not_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, hibernate_async),
+ is_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, snooze_async),
+ is_in_erlang_hibernate(Pid),
+ ok = gen_statem:cast(Pid, wakeup_async),
+ is_not_in_erlang_hibernate(Pid),
+
+ hibernating = gen_statem:call(Pid, hibernate_sync),
+ is_in_erlang_hibernate(Pid),
+ sys:suspend(Pid),
+ is_in_erlang_hibernate(Pid),
+ sys:resume(Pid),
+ is_in_erlang_hibernate(Pid),
+ receive after 1000 -> ok end,
+ is_in_erlang_hibernate(Pid),
+
+ good_morning = gen_statem:call(Pid, wakeup_sync),
+ is_not_in_erlang_hibernate(Pid),
+ stop_it(Pid),
+ process_flag(trap_exit, OldFl),
+ receive
+ {'EXIT',Pid,normal} -> ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+ ok = verify_empty_msgq().
+
+is_in_erlang_hibernate(Pid) ->
+ receive after 1 -> ok end,
+ is_in_erlang_hibernate_1(200, Pid).
+
+is_in_erlang_hibernate_1(0, Pid) ->
+ ct:log("~p\n", [erlang:process_info(Pid, current_function)]),
+ ct:fail(not_in_erlang_hibernate_3);
+is_in_erlang_hibernate_1(N, Pid) ->
+ {current_function,MFA} = erlang:process_info(Pid, current_function),
+ case MFA of
+ {erlang,hibernate,3} ->
+ ok;
+ _ ->
+ receive after 10 -> ok end,
+ is_in_erlang_hibernate_1(N-1, Pid)
+ end.
+
+is_not_in_erlang_hibernate(Pid) ->
+ receive after 1 -> ok end,
+ is_not_in_erlang_hibernate_1(200, Pid).
+
+is_not_in_erlang_hibernate_1(0, Pid) ->
+ ct:log("~p\n", [erlang:process_info(Pid, current_function)]),
+ ct:fail(not_in_erlang_hibernate_3);
+is_not_in_erlang_hibernate_1(N, Pid) ->
+ {current_function,MFA} = erlang:process_info(Pid, current_function),
+ case MFA of
+ {erlang,hibernate,3} ->
+ receive after 10 -> ok end,
+ is_not_in_erlang_hibernate_1(N-1, Pid);
+ _ ->
+ ok
+ end.
+
+
+enter_loop(_Config) ->
+ OldFlag = process_flag(trap_exit, true),
+
+ dummy_via:reset(),
+
+ %% Locally registered process + {local,Name}
+ {ok,Pid1a} =
+ proc_lib:start_link(?MODULE, enter_loop, [local,local]),
+ yes = gen_statem:call(Pid1a, 'alive?'),
+ stopped = gen_statem:call(Pid1a, stop),
+ receive
+ {'EXIT',Pid1a,normal} ->
+ ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ %% Unregistered process + {local,Name}
+ {ok,Pid1b} =
+ proc_lib:start_link(?MODULE, enter_loop, [anon,local]),
+ receive
+ {'EXIT',Pid1b,process_not_registered} ->
+ ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ %% Globally registered process + {global,Name}
+ {ok,Pid2a} =
+ proc_lib:start_link(?MODULE, enter_loop, [global,global]),
+ yes = gen_statem:call(Pid2a, 'alive?'),
+ stopped = gen_statem:call(Pid2a, stop),
+ receive
+ {'EXIT',Pid2a,normal} ->
+ ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ %% Unregistered process + {global,Name}
+ {ok,Pid2b} =
+ proc_lib:start_link(?MODULE, enter_loop, [anon,global]),
+ receive
+ {'EXIT',Pid2b,process_not_registered_globally} ->
+ ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ %% Unregistered process + no name
+ {ok,Pid3} =
+ proc_lib:start_link(?MODULE, enter_loop, [anon,anon]),
+ yes = gen_statem:call(Pid3, 'alive?'),
+ stopped = gen_statem:call(Pid3, stop),
+ receive
+ {'EXIT',Pid3,normal} ->
+ ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ %% Process not started using proc_lib
+ CallbackMode = state_functions,
+ Pid4 =
+ spawn_link(
+ gen_statem, enter_loop,
+ [?MODULE,[],CallbackMode,state0,[]]),
+ receive
+ {'EXIT',Pid4,process_was_not_started_by_proc_lib} ->
+ ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ %% Make sure I am the parent, ie that ordering a shutdown will
+ %% result in the process terminating with Reason==shutdown
+ {ok,Pid5} =
+ proc_lib:start_link(?MODULE, enter_loop, [anon,anon]),
+ yes = gen_statem:call(Pid5, 'alive?'),
+ exit(Pid5, shutdown),
+ receive
+ {'EXIT',Pid5,shutdown} ->
+ ok
+ after 5000 ->
+ ct:fail(gen_statem_did_not_die)
+ end,
+
+ %% Make sure gen_statem:enter_loop does not accept {local,Name}
+ %% when it's another process than the calling one which is
+ %% registered under that name
+ register(armitage, self()),
+ {ok,Pid6a} =
+ proc_lib:start_link(?MODULE, enter_loop, [anon,local]),
+ receive
+ {'EXIT',Pid6a,process_not_registered} ->
+ ok
+ after 1000 ->
+ ct:fail(gen_statem_started)
+ end,
+ unregister(armitage),
+
+ %% Make sure gen_statem:enter_loop does not accept {global,Name}
+ %% when it's another process than the calling one which is
+ %% registered under that name
+ global:register_name(armitage, self()),
+ {ok,Pid6b} =
+ proc_lib:start_link(?MODULE, enter_loop, [anon,global]),
+ receive
+ {'EXIT',Pid6b,process_not_registered_globally} ->
+ ok
+ after 1000 ->
+ ct:fail(gen_statem_started)
+ end,
+ global:unregister_name(armitage),
+
+ dummy_via:register_name(armitage, self()),
+ {ok,Pid6c} =
+ proc_lib:start_link(?MODULE, enter_loop, [anon,via]),
+ receive
+ {'EXIT',Pid6c,{process_not_registered_via,dummy_via}} ->
+ ok
+ after 1000 ->
+ ct:fail(
+ {gen_statem_started,
+ process_info(self(), messages)})
+ end,
+ dummy_via:unregister_name(armitage),
+
+ process_flag(trap_exit, OldFlag),
+ ok = verify_empty_msgq().
+
+enter_loop(Reg1, Reg2) ->
+ process_flag(trap_exit, true),
+ case Reg1 of
+ local -> register(armitage, self());
+ global -> global:register_name(armitage, self());
+ via -> dummy_via:register_name(armitage, self());
+ anon -> ignore
+ end,
+ proc_lib:init_ack({ok, self()}),
+ CallbackMode = state_functions,
+ case Reg2 of
+ local ->
+ gen_statem:enter_loop(
+ ?MODULE, [], CallbackMode, state0, [], {local,armitage});
+ global ->
+ gen_statem:enter_loop(
+ ?MODULE, [], CallbackMode, state0, [], {global,armitage});
+ via ->
+ gen_statem:enter_loop(
+ ?MODULE, [], CallbackMode, state0, [],
+ {via, dummy_via, armitage});
+ anon ->
+ gen_statem:enter_loop(
+ ?MODULE, [], CallbackMode, state0, [])
+ end.
+
+
+%% Test the order for multiple {next_event,T,C}
+next_events(Config) ->
+ {ok,Pid} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+ ok = gen_statem:cast(Pid, next_event),
+ {state,next_events,[]} = gen_statem:call(Pid, get),
+ ok = gen_statem:stop(Pid),
+ false = erlang:is_process_alive(Pid),
+ noproc =
+ ?EXPECT_FAILURE(gen_statem:stop(Pid), Reason).
+
+
+%%
+%% Functionality check
+%%
+
+wfor(Msg) ->
+ receive
+ Msg -> ok
+ after 5000 ->
+ error(timeout)
+ end.
+
+
+stop_it(STM) ->
+ stopped = gen_statem:call(STM, stop),
+ check_stopped(STM).
+
+
+check_stopped(STM) ->
+ Call = there_you_are,
+ {_,{gen_statem,call,[_,Call,infinity]}} =
+ ?EXPECT_FAILURE(gen_statem:call(STM, Call), Reason),
+ ok.
+
+
+do_func_test(STM) ->
+ ok = gen_statem:cast(STM, {'alive?',self()}),
+ wfor(yes),
+ ok = do_connect(STM),
+ ok = gen_statem:cast(STM, {'alive?',self()}),
+ wfor(yes),
+ ?t:do_times(3, ?MODULE, do_msg, [STM]),
+ ok = gen_statem:cast(STM, {'alive?',self()}),
+ wfor(yes),
+ ok = do_disconnect(STM),
+ ok = gen_statem:cast(STM, {'alive?',self()}),
+ wfor(yes),
+ ok.
+
+
+do_connect(STM) ->
+ check_state(STM, idle),
+ gen_statem:cast(STM, {connect,self()}),
+ wfor(accept),
+ check_state(STM, wfor_conf),
+ Tag = make_ref(),
+ gen_statem:cast(STM, {ping,self(),Tag}),
+ gen_statem:cast(STM, confirm),
+ wfor({pong,Tag}),
+ check_state(STM, connected),
+ ok.
+
+do_msg(STM) ->
+ check_state(STM, connected),
+ R = make_ref(),
+ ok = gen_statem:cast(STM, {msg,self(),R}),
+ wfor({ack,R}).
+
+
+do_disconnect(STM) ->
+ ok = gen_statem:cast(STM, disconnect),
+ check_state(STM, idle).
+
+check_state(STM, State) ->
+ case gen_statem:call(STM, get) of
+ {state, State, _} -> ok
+ end.
+
+do_sync_func_test(STM) ->
+ yes = gen_statem:call(STM, 'alive?'),
+ ok = do_sync_connect(STM),
+ yes = gen_statem:call(STM, 'alive?'),
+ ?t:do_times(3, ?MODULE, do_sync_msg, [STM]),
+ yes = gen_statem:call(STM, 'alive?'),
+ ok = do_sync_disconnect(STM),
+ yes = gen_statem:call(STM, 'alive?'),
+ check_state(STM, idle),
+ ok = gen_statem:call(STM, {timeout,200}),
+ yes = gen_statem:call(STM, 'alive?'),
+ check_state(STM, idle),
+ ok.
+
+
+do_sync_connect(STM) ->
+ check_state(STM, idle),
+ accept = gen_statem:call(STM, connect),
+ check_state(STM, wfor_conf),
+ Tag = make_ref(),
+ gen_statem:cast(STM, {ping,self(),Tag}),
+ yes = gen_statem:call(STM, confirm),
+ wfor({pong,Tag}),
+ check_state(STM, connected),
+ ok.
+
+do_sync_msg(STM) ->
+ check_state(STM, connected),
+ R = make_ref(),
+ {ack,R} = gen_statem:call(STM, {msg,R}),
+ ok.
+
+do_sync_disconnect(STM) ->
+ yes = gen_statem:call(STM, disconnect),
+ check_state(STM, idle).
+
+
+verify_empty_msgq() ->
+ [] = flush(),
+ ok.
+
+start_arg(Config, Arg) ->
+ case lists:keyfind(callback_mode, 1, Config) of
+ {_,CallbackMode} ->
+ {callback_mode,CallbackMode,Arg};
+ false ->
+ Arg
+ end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%
+%% The State Machine
+%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+init(ignore) ->
+ ignore;
+init(stop) ->
+ {stop,stopped};
+init(stop_shutdown) ->
+ {stop,shutdown};
+init(sleep) ->
+ ?t:sleep(1000),
+ {state_functions,idle,data};
+init(hiber) ->
+ {state_functions,hiber_idle,[]};
+init(hiber_now) ->
+ {state_functions,hiber_idle,[],[hibernate]};
+init({data, Data}) ->
+ {state_functions,idle,Data};
+init({callback_mode,CallbackMode,Arg}) ->
+ case init(Arg) of
+ {_,State,Data,Ops} ->
+ {CallbackMode,State,Data,Ops};
+ {_,State,Data} ->
+ {CallbackMode,State,Data};
+ Other ->
+ Other
+ end;
+init({map_statem,#{init := Init}=Machine}) ->
+ case Init() of
+ {ok,State,Data,Ops} ->
+ {handle_event_function,State,[Data|Machine],Ops};
+ {ok,State,Data} ->
+ {handle_event_function,State,[Data|Machine]};
+ Other ->
+ Other
+ end;
+init([]) ->
+ {state_functions,idle,data}.
+
+terminate(_, _State, crash_terminate) ->
+ exit({crash,terminate});
+terminate({From,stopped}, State, _Data) ->
+ From ! {self(),{stopped,State}},
+ ok;
+terminate(_Reason, _State, _Data) ->
+ ok.
+
+
+%% State functions
+
+idle(cast, {connect,Pid}, Data) ->
+ Pid ! accept,
+ {next_state,wfor_conf,Data,infinity}; % NoOp timeout just to test API
+idle({call,From}, connect, Data) ->
+ gen_statem:reply(From, accept),
+ {next_state,wfor_conf,Data,infinity}; % NoOp timeout just to test API
+idle(cast, badreturn, _Data) ->
+ badreturn;
+idle({call,_From}, badreturn, _Data) ->
+ badreturn;
+idle({call,From}, {delayed_answer,T}, Data) ->
+ receive
+ after T ->
+ gen_statem:reply({reply,From,delayed}),
+ throw({keep_state,Data})
+ end;
+idle({call,From}, {timeout,Time}, _Data) ->
+ {next_state,timeout,{From,Time},
+ {timeout,Time,idle}};
+idle(cast, next_event, _Data) ->
+ {next_state,next_events,[a,b,c],
+ [{next_event,internal,a},
+ {next_event,internal,b},
+ {next_event,internal,c}]};
+idle(Type, Content, Data) ->
+ case handle_common_events(Type, Content, idle, Data) of
+ undefined ->
+ case Type of
+ {call,From} ->
+ throw({keep_state,Data,[{reply,From,'eh?'}]});
+ _ ->
+ throw(
+ {stop,{unexpected,idle,Type,Content}})
+ end;
+ Result ->
+ Result
+ end.
+
+timeout(timeout, idle, {From,Time}) ->
+ TRef = erlang:start_timer(Time, self(), ok),
+ {keep_state,{From,TRef},0}; % Immediate timeout 0
+timeout(timeout, 0, {From,TRef}) ->
+ {next_state,timeout2,{From,TRef},
+ [{timeout,1,should_be_cancelled},
+ postpone]}; % Should cancel state timeout
+timeout(_, _, _) ->
+ keep_state_and_data.
+
+timeout2(timeout, 0, _) ->
+ keep_state_and_data;
+timeout2(timeout, Reason, _) ->
+ {stop,Reason};
+timeout2(info, {timeout,TRef,Result}, {From,TRef}) ->
+ gen_statem:reply([{reply,From,Result}]),
+ {next_state,idle,state};
+timeout2(_, _, _) ->
+ {keep_state_and_data,[]}.
+
+wfor_conf({call,From}, confirm, Data) ->
+ {next_state,connected,Data,
+ {reply,From,yes}};
+wfor_conf(cast, {ping,_,_}, _) ->
+ {keep_state_and_data,[postpone]};
+wfor_conf(cast, confirm, Data) ->
+ {next_state,connected,Data};
+wfor_conf(Type, Content, Data) ->
+ case handle_common_events(Type, Content, wfor_conf, Data) of
+ undefined ->
+ case Type of
+ {call,From} ->
+ {next_state,idle,Data,
+ [{reply,From,'eh?'}]};
+ _ ->
+ throw(keep_state_and_data)
+ end;
+ Result ->
+ Result
+ end.
+
+connected({call,From}, {msg,Ref}, Data) ->
+ {keep_state,Data,
+ {reply,From,{ack,Ref}}};
+connected(cast, {msg,From,Ref}, Data) ->
+ From ! {ack,Ref},
+ {keep_state,Data};
+connected({call,From}, disconnect, Data) ->
+ {next_state,idle,Data,
+ [{reply,From,yes}]};
+connected(cast, disconnect, Data) ->
+ {next_state,idle,Data};
+connected(cast, {ping,Pid,Tag}, Data) ->
+ Pid ! {pong,Tag},
+ {keep_state,Data};
+connected(Type, Content, Data) ->
+ case handle_common_events(Type, Content, connected, Data) of
+ undefined ->
+ case Type of
+ {call,From} ->
+ {keep_state,Data,
+ [{reply,From,'eh?'}]};
+ _ ->
+ {keep_state,Data}
+ end;
+ Result ->
+ Result
+ end.
+
+state0({call,From}, stop, Data) ->
+ {stop_and_reply,normal,[{reply,From,stopped}],Data};
+state0(Type, Content, Data) ->
+ case handle_common_events(Type, Content, state0, Data) of
+ undefined ->
+ {keep_state,Data};
+ Result ->
+ Result
+ end.
+
+hiber_idle({call,From}, 'alive?', Data) ->
+ {keep_state,Data,
+ [{reply,From,'alive!'}]};
+hiber_idle({call,From}, hibernate_sync, Data) ->
+ {next_state,hiber_wakeup,Data,
+ [{reply,From,hibernating},
+ hibernate]};
+hiber_idle(info, hibernate_later, _) ->
+ Tref = erlang:start_timer(1000, self(), hibernate),
+ {keep_state,Tref};
+hiber_idle(info, hibernate_now, Data) ->
+ {keep_state,Data,
+ [hibernate]};
+hiber_idle(info, {timeout,Tref,hibernate}, Tref) ->
+ {keep_state,[],
+ [hibernate]};
+hiber_idle(cast, hibernate_async, Data) ->
+ {next_state,hiber_wakeup,Data,
+ [hibernate]};
+hiber_idle(Type, Content, Data) ->
+ case handle_common_events(Type, Content, hiber_idle, Data) of
+ undefined ->
+ {keep_state,Data};
+ Result ->
+ Result
+ end.
+
+hiber_wakeup({call,From}, wakeup_sync, Data) ->
+ {next_state,hiber_idle,Data,
+ [{reply,From,good_morning}]};
+hiber_wakeup({call,From}, snooze_sync, Data) ->
+ {keep_state,Data,
+ [{reply,From,please_just_five_more},
+ hibernate]};
+hiber_wakeup(cast, wakeup_async, Data) ->
+ {next_state,hiber_idle,Data};
+hiber_wakeup(cast, snooze_async, Data) ->
+ {keep_state,Data,
+ [hibernate]};
+hiber_wakeup(Type, Content, Data) ->
+ case handle_common_events(Type, Content, hiber_wakeup, Data) of
+ undefined ->
+ {keep_state,Data};
+ Result ->
+ Result
+ end.
+
+next_events(internal, Msg, [Msg|Msgs]) ->
+ {keep_state,Msgs};
+next_events(Type, Content, Data) ->
+ case handle_common_events(Type, Content, next_events, Data) of
+ undefined ->
+ {keep_state,Data};
+ Result ->
+ Result
+ end.
+
+
+handle_common_events({call,From}, get, State, Data) ->
+ {keep_state,Data,
+ [{reply,From,{state,State,Data}}]};
+handle_common_events(cast, {get,Pid}, State, Data) ->
+ Pid ! {state,State,Data},
+ {keep_state,Data};
+handle_common_events({call,From}, stop, _, Data) ->
+ {stop_and_reply,normal,[{reply,From,stopped}],Data};
+handle_common_events(cast, stop, _, _) ->
+ stop;
+handle_common_events({call,From}, {stop,Reason}, _, Data) ->
+ {stop_and_reply,Reason,{reply,From,stopped},Data};
+handle_common_events(cast, {stop,Reason}, _, _) ->
+ {stop,Reason};
+handle_common_events({call,From}, 'alive?', _, Data) ->
+ {keep_state,Data,
+ [{reply,From,yes}]};
+handle_common_events(cast, {'alive?',Pid}, _, Data) ->
+ Pid ! yes,
+ {keep_state,Data};
+handle_common_events(_, _, _, _) ->
+ undefined.
+
+%% Wrapper state machine that uses a map state machine spec
+handle_event(
+ Type, Event, State, [Data|Machine])
+ when is_map(Machine) ->
+ #{State := HandleEvent} = Machine,
+ case
+ try HandleEvent(Type, Event, Data) of
+ Result ->
+ Result
+ catch
+ Result ->
+ Result
+ end of
+ {stop,Reason,NewData} ->
+ {stop,Reason,[NewData|Machine]};
+ {next_state,NewState,NewData} ->
+ {next_state,NewState,[NewData|Machine]};
+ {next_state,NewState,NewData,Ops} ->
+ {next_state,NewState,[NewData|Machine],Ops};
+ {keep_state,NewData} ->
+ {keep_state,[NewData|Machine]};
+ {keep_state,NewData,Ops} ->
+ {keep_state,[NewData|Machine],Ops};
+ Other ->
+ Other
+ end;
+%%
+%% Dispatcher to test callback_mode handle_event_function
+%%
+%% Wrap the state in a 1 element list just to test non-atom
+%% states. Note that the state from init/1 is not wrapped
+%% so both atom and non-atom states are tested.
+handle_event(Type, Event, State, Data) ->
+ StateName = unwrap_state(State),
+ try ?MODULE:StateName(Type, Event, Data) of
+ Result ->
+ wrap_result(Result)
+ catch
+ throw:Result ->
+ erlang:raise(
+ throw, wrap_result(Result), erlang:get_stacktrace())
+ end.
+
+unwrap_state([State]) ->
+ State;
+unwrap_state(State) ->
+ State.
+
+wrap_result(Result) ->
+ case Result of
+ {next_state,NewState,NewData} ->
+ {next_state,[NewState],NewData};
+ {next_state,NewState,NewData,StateOps} ->
+ {next_state,[NewState],NewData,StateOps};
+ Other ->
+ Other
+ end.
+
+
+
+code_change(OldVsn, State, Data, CallbackMode) ->
+ {CallbackMode,State,{OldVsn,Data,CallbackMode}}.
+
+format_status(terminate, [_Pdict,State,Data]) ->
+ {formatted,State,Data};
+format_status(normal, [_Pdict,_State,_Data]) ->
+ [format_status_called].
+
+flush() ->
+ receive
+ Msg ->
+ [Msg|flush()]
+ after 500 ->
+ []
+ end.
diff --git a/lib/tools/doc/src/erlang_mode.xml b/lib/tools/doc/src/erlang_mode.xml
index 0ab272fb2f..00cf5196b4 100644
--- a/lib/tools/doc/src/erlang_mode.xml
+++ b/lib/tools/doc/src/erlang_mode.xml
@@ -252,6 +252,7 @@
behavior</item>
<item>gen_event - skeleton for the OTP gen_event behavior</item>
<item>gen_fsm - skeleton for the OTP gen_fsm behavior</item>
+ <item>gen_statem - skeleton for the OTP gen_statem behavior</item>
<item>Library module - skeleton for a module that does not
implement a process.</item>
<item>Corba callback - skeleton for a Corba callback module.</item>
diff --git a/lib/tools/emacs/erlang-skels.el b/lib/tools/emacs/erlang-skels.el
index 3bb1dda6db..ce26c83295 100644
--- a/lib/tools/emacs/erlang-skels.el
+++ b/lib/tools/emacs/erlang-skels.el
@@ -56,6 +56,8 @@
erlang-skel-gen-event erlang-skel-header)
("gen_fsm" "gen-fsm"
erlang-skel-gen-fsm erlang-skel-header)
+ ("gen_statem" "gen-statem"
+ erlang-skel-gen-statem erlang-skel-header)
("wx_object" "wx-object"
erlang-skel-wx-object erlang-skel-header)
("Library module" "gen-lib"
@@ -858,6 +860,122 @@ Please see the function `tempo-define-template'.")
"*The template of a gen_fsm.
Please see the function `tempo-define-template'.")
+(defvar erlang-skel-gen-statem
+ '((erlang-skel-include erlang-skel-large-header)
+ "-behaviour(gen_statem)." n n
+
+ "%% API" n
+ "-export([start_link/0])." n
+ n
+ "%% gen_statem callbacks" n
+ "-export([init/1, terminate/3, code_change/4])." n
+ "-export([state_name/3])." n
+ "-export([handle_event/4])." n
+ n
+ "-define(SERVER, ?MODULE)." n
+ n
+ "-record(data, {})." n
+ n
+ (erlang-skel-double-separator-start 3)
+ "%%% API" n
+ (erlang-skel-double-separator-end 3) n
+ (erlang-skel-separator-start 2)
+ "%% @doc" n
+ "%% Creates a gen_statem process which calls Module:init/1 to" n
+ "%% initialize. To ensure a synchronized start-up procedure, this" n
+ "%% function does not return until Module:init/1 has returned." n
+ "%%" n
+ (erlang-skel-separator-end 2)
+ "-spec start_link() ->" n>
+ "{ok, Pid :: pid()} |" n>
+ "ignore |" n>
+ "{error, Error :: term()}." n
+ "start_link() ->" n>
+ "gen_statem:start_link({local, ?SERVER}, ?MODULE, [], [])." n
+ n
+ (erlang-skel-double-separator-start 3)
+ "%%% gen_statem callbacks" n
+ (erlang-skel-double-separator-end 3) n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% Whenever a gen_statem is started using gen_statem:start/[3,4] or" n
+ "%% gen_statem:start_link/[3,4], this function is called by the new" n
+ "%% process to initialize." n
+ (erlang-skel-separator-end 2)
+ "-spec init(Args :: term()) -> " n>
+ "{gen_statem:callback_mode()," n>
+ "State :: term(), Data :: term()} |" n>
+ "{gen_statem:callback_mode()," n>
+ "State :: term(), Data :: term()," n>
+ "[gen_statem:action()] | gen_statem:action()} |" n>
+ "ignore |" n>
+ "{stop, Reason :: term()}." n
+ "init([]) ->" n>
+ "{state_functions, state_name, #data{}}." n
+ n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% If the gen_statem runs with CallbackMode =:= state_functions" n
+ "%% there should be one instance of this function for each possible" n
+ "%% state name. Whenever a gen_statem receives an event," n
+ "%% the instance of this function with the same name" n
+ "%% as the current state name StateName is called to" n
+ "%% handle the event." n
+ (erlang-skel-separator-end 2)
+ "-spec state_name(" n>
+ "gen_statem:event_type(), Msg :: term()," n>
+ "Data :: term()) ->" n>
+ "gen_statem:state_function_result(). " n
+ "state_name({call,Caller}, _Msg, Data) ->" n>
+ "{next_state, state_name, Data, [{reply,Caller,ok}]}." n
+ n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% If the gen_statem runs with CallbackMode =:= handle_event_function" n
+ "%% this function is called for every event a gen_statem receives." n
+ (erlang-skel-separator-end 2)
+ "-spec handle_event(" n>
+ "gen_statem:event_type(), Msg :: term()," n>
+ "State :: term(), Data :: term()) ->" n>
+ "gen_statem:handle_event_result(). " n
+ "handle_event({call,From}, _Msg, State, Data) ->" n>
+ "{next_state, State, Data, [{reply,From,ok}]}." n
+ n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% This function is called by a gen_statem when it is about to" n
+ "%% terminate. It should be the opposite of Module:init/1 and do any" n
+ "%% necessary cleaning up. When it returns, the gen_statem terminates with" n
+ "%% Reason. The return value is ignored." n
+ (erlang-skel-separator-end 2)
+ "-spec terminate(Reason :: term(), State :: term(), Data :: term()) ->" n>
+ "any()." n
+ "terminate(_Reason, _State, _Data) ->" n>
+ "void." n
+ n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% Convert process state when code is changed" n
+ (erlang-skel-separator-end 2)
+ "-spec code_change(" n>
+ "OldVsn :: term() | {down,term()}," n>
+ "State :: term(), Data :: term(), Extra :: term()) ->" n>
+ "{ok, NewState :: term(), NewData :: term()}." n
+ "code_change(_OldVsn, State, Data, _Extra) ->" n>
+ "{ok, State, Data}." n
+ n
+ (erlang-skel-double-separator-start 3)
+ "%%% Internal functions" n
+ (erlang-skel-double-separator-end 3)
+ )
+ "*The template of a gen_statem.
+Please see the function `tempo-define-template'.")
+
(defvar erlang-skel-wx-object
'((erlang-skel-include erlang-skel-large-header)
"-behaviour(wx_object)." n n
diff --git a/system/doc/definitions/term.defs b/system/doc/definitions/term.defs
index 6091a46a20..921175a7f0 100644
--- a/system/doc/definitions/term.defs
+++ b/system/doc/definitions/term.defs
@@ -76,6 +76,7 @@ the module Erlang in the application kernel","kenneth"},
{"gen_event","gen_event","A behaviour used for programming event handling mechanisms, such as alarm handlers, error loggers, and plug-and-play handlers.","mbj"},
{"gen_fsm","gen_fsm","A behaviour used for programming finite state machines.","mbj"},
{"gen_server","gen_server","A behaviour used for programming client-server processes.","mbj"},
+{"gen_statem","gen_statem","A behaviour used for programming generic state machines.","raimo"},
{"gterm","Global Glossary Database","A glossary database used to list common acronymns and defintions etc.","jocke"},
{"xref","xref","A cross reference tool that can be used for finding dependencies between functions, modules, applications and releases. Part of the Tools application.","gunilla"},
{"GSlong","Graphics System","A library module which provides a graphics interface for Erlang.","mbj"},
diff --git a/system/doc/design_principles/Makefile b/system/doc/design_principles/Makefile
index 653072bc65..937b3e28c8 100644
--- a/system/doc/design_principles/Makefile
+++ b/system/doc/design_principles/Makefile
@@ -58,6 +58,12 @@ GIF_FILES = \
sup5.gif \
sup6.gif
+PNG_FILES = \
+ code_lock.png \
+ code_lock_2.png
+
+IMAGE_FILES = $(GIF_FILES) $(PNG_FILES)
+
XML_FILES = \
$(BOOK_FILES) $(XML_CHAPTER_FILES) \
$(XML_PART_FILES)
@@ -85,13 +91,16 @@ _create_dirs := $(shell mkdir -p $(HTMLDIR))
$(HTMLDIR)/%.gif: %.gif
$(INSTALL_DATA) $< $@
+$(HTMLDIR)/%.png: %.png
+ $(INSTALL_DATA) $< $@
+
docs: html
local_docs: PDFDIR=../../pdf
-html: $(HTML_UG_FILE) gifs
+html: $(HTML_UG_FILE) images
-gifs: $(GIF_FILES:%=$(HTMLDIR)/%)
+images: $(IMAGE_FILES:%=$(HTMLDIR)/%)
debug opt:
@@ -109,7 +118,7 @@ release_docs_spec: docs
# $(INSTALL_DIR) "$(RELEASE_PATH)/pdf"
# $(INSTALL_DATA) $(TOP_PDF_FILE) "$(RELEASE_PATH)/pdf"
$(INSTALL_DIR) $(RELSYSDIR)
- $(INSTALL_DATA) $(GIF_FILES) $(HTMLDIR)/*.html \
+ $(INSTALL_DATA) $(IMAGE_FILES) $(HTMLDIR)/*.html \
$(RELSYSDIR)
diff --git a/system/doc/design_principles/appup_cookbook.xml b/system/doc/design_principles/appup_cookbook.xml
index 417b482fba..4f23c42c59 100644
--- a/system/doc/design_principles/appup_cookbook.xml
+++ b/system/doc/design_principles/appup_cookbook.xml
@@ -50,7 +50,8 @@
<p>In a system implemented according to the OTP design principles,
all processes, except system processes and special processes,
reside in one of the behaviours <c>supervisor</c>,
- <c>gen_server</c>, <c>gen_fsm</c>, or <c>gen_event</c>. These
+ <c>gen_server</c>, <c>gen_fsm</c>,
+ <c>gen_statem</c> or <c>gen_event</c>. These
belong to the STDLIB application and upgrading/downgrading
normally requires an emulator restart.</p>
<p>OTP thus provides no support for changing residence modules except
diff --git a/system/doc/design_principles/code_lock.dia b/system/doc/design_principles/code_lock.dia
new file mode 100644
index 0000000000..bed6d8ee86
--- /dev/null
+++ b/system/doc/design_principles/code_lock.dia
Binary files differ
diff --git a/system/doc/design_principles/code_lock.png b/system/doc/design_principles/code_lock.png
new file mode 100644
index 0000000000..e40f0320aa
--- /dev/null
+++ b/system/doc/design_principles/code_lock.png
Binary files differ
diff --git a/system/doc/design_principles/code_lock_2.dia b/system/doc/design_principles/code_lock_2.dia
new file mode 100644
index 0000000000..4e82a9e1d6
--- /dev/null
+++ b/system/doc/design_principles/code_lock_2.dia
Binary files differ
diff --git a/system/doc/design_principles/code_lock_2.png b/system/doc/design_principles/code_lock_2.png
new file mode 100644
index 0000000000..138fbdef6c
--- /dev/null
+++ b/system/doc/design_principles/code_lock_2.png
Binary files differ
diff --git a/system/doc/design_principles/des_princ.xml b/system/doc/design_principles/des_princ.xml
index 0cf9f28bdc..8ab8661c2d 100644
--- a/system/doc/design_principles/des_princ.xml
+++ b/system/doc/design_principles/des_princ.xml
@@ -226,7 +226,9 @@ free(Ch, {Alloc, Free} = Channels) ->
<item><p><seealso marker="gen_server_concepts">gen_server</seealso></p>
<p>For implementing the server of a client-server relation</p></item>
<item><p><seealso marker="fsm">gen_fsm</seealso></p>
- <p>For implementing finite-state machines</p></item>
+ <p>For implementing finite-state machines (Old)</p></item>
+ <item><p><seealso marker="statem">gen_statem</seealso></p>
+ <p>For implementing state machines (New)</p></item>
<item><p><seealso marker="events">gen_event</seealso></p>
<p>For implementing event handling functionality</p></item>
<item><p><seealso marker="sup_princ">supervisor</seealso></p>
diff --git a/system/doc/design_principles/fsm.xml b/system/doc/design_principles/fsm.xml
index f20d20fb7e..3468f93ae0 100644
--- a/system/doc/design_principles/fsm.xml
+++ b/system/doc/design_principles/fsm.xml
@@ -30,6 +30,16 @@
<file>fsm.xml</file>
</header>
<marker id="gen_fsm behaviour"></marker>
+ <note>
+ <p>
+ There is a new behaviour
+ <seealso marker="gen_statem"><c>gen_statem</c></seealso>
+ that is intended to replace <c>gen_fsm</c> for new code.
+ It has the same features and add some really useful.
+ This module will not be removed for the foreseeable future
+ to keep old state machine implementations running.
+ </p>
+ </note>
<p>This section is to be read with the <c>gen_fsm(3)</c> manual page
in STDLIB, where all interface functions and callback
functions are described in detail.</p>
diff --git a/system/doc/design_principles/part.xml b/system/doc/design_principles/part.xml
index 7862a2d650..6495211e04 100644
--- a/system/doc/design_principles/part.xml
+++ b/system/doc/design_principles/part.xml
@@ -31,6 +31,7 @@
<xi:include href="des_princ.xml"/>
<xi:include href="gen_server_concepts.xml"/>
<xi:include href="fsm.xml"/>
+ <xi:include href="statem.xml"/>
<xi:include href="events.xml"/>
<xi:include href="sup_princ.xml"/>
<xi:include href="spec_proc.xml"/>
diff --git a/system/doc/design_principles/release_handling.xml b/system/doc/design_principles/release_handling.xml
index c38cca248f..4f71ad4437 100644
--- a/system/doc/design_principles/release_handling.xml
+++ b/system/doc/design_principles/release_handling.xml
@@ -249,7 +249,7 @@
<p>If <c>Modules=dynamic</c>, which is the case for event
managers, the event manager process informs the release handler
about the list of currently installed event handlers
- (<c>gen_fsm</c>), and it is checked if the module name is in
+ (<c>gen_event</c>), and it is checked if the module name is in
this list instead.</p>
<p>The release handler suspends, asks for code change, and
resumes processes by calling the functions
diff --git a/system/doc/design_principles/statem.xml b/system/doc/design_principles/statem.xml
new file mode 100644
index 0000000000..a4b8fb06a0
--- /dev/null
+++ b/system/doc/design_principles/statem.xml
@@ -0,0 +1,1451 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+ <header>
+ <copyright>
+ <year>2016</year>
+ <holder>Ericsson AB. All Rights Reserved.</holder>
+ </copyright>
+ <legalnotice>
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+ </legalnotice>
+
+ <title>gen_statem Behaviour</title>
+ <prepared></prepared>
+ <docno></docno>
+ <date></date>
+ <rev></rev>
+ <file>statem.xml</file>
+ </header>
+ <marker id="gen_statem behaviour"></marker>
+ <p>
+ This section is to be read with the
+ <seealso marker="stdlib:gen_statem"><c>gen_statem(3)</c></seealso>
+ manual page in STDLIB, where all interface functions and callback
+ functions are described in detail.
+ </p>
+ <p>
+ This is a new behaviour in OTP-19.0.
+ It has been thoroughly reviewed, is stable enough
+ to be used by at least two heavy OTP applications, and is here to stay.
+ But depending on user feedback, we do not expect
+ but might find it necessary to make minor
+ not backwards compatible changes into OTP-20.0,
+ so its state can be designated as "not quite experimental"...
+ </p>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Event Driven State Machines</title>
+ <p>
+ Established Automata theory does not deal much with
+ how a state transition is triggered,
+ but in general assumes that the output is a function
+ of the input (and the state) and that they are
+ some kind of values.
+ </p>
+ <p>
+ For an Event Driven State Machine the input is an event
+ that triggers a state transition and the output
+ is actions executed during the state transition.
+ It can analogously to the mathematical model of a
+ Finite State Machine be described as
+ a set of relations of the form:
+ </p>
+ <pre>
+State(S) x Event(E) -> Actions(A), State(S')</pre>
+ <p>These relations are interpreted as meaning:</p>
+ <p>
+ If we are in state <c>S</c> and event <c>E</c> occurs, we
+ are to perform actions <c>A</c> and make a transition to
+ state <c>S'</c>.
+ </p>
+ <p>
+ Note that <c>S'</c> may be equal to <c>S</c>.
+ </p>
+ <p>
+ Since <c>A</c> and <c>S'</c> depend only on
+ <c>S</c> and <c>E</c> the kind of state machine described
+ here is a Mealy Machine.
+ (See for example the corresponding Wikipedia article)
+ </p>
+ <p>
+ Like most <c>gen_</c> behaviours, <c>gen_statem</c> keeps
+ a server <c>Data</c> besides the state. This and the fact that
+ there is no restriction on the number of states
+ (assuming enough virtual machine memory)
+ or on the number of distinct input events actually makes
+ a state machine implemented with this behaviour Turing complete.
+ But it feels mostly like an Event Driven Mealy Machine.
+ </p>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <marker id="callback_modes" />
+ <title>Callback Modes</title>
+ <p>
+ The <c>gen_statem</c> behaviour supports two different callback modes.
+ In the mode
+ <seealso marker="stdlib:gen_statem#type-callback_mode">
+ <c>state_functions</c>,
+ </seealso>
+ the state transition rules are written as a number of Erlang
+ functions, which conform to the following convention:
+ </p>
+ <pre>
+StateName(EventType, EventContent, Data) ->
+ .. code for actions here ...
+ {next_state, NewStateName, NewData}.</pre>
+ <p>
+ In the mode
+ <seealso marker="stdlib:gen_statem#type-callback_mode">
+ <c>handle_event_function</c>
+ </seealso>
+ there is only one
+ Erlang function that implements all state transition rules:
+ </p>
+ <pre>
+handle_event(EventType, EventContent, State, Data) ->
+ .. code for actions here ...
+ {next_state, State', Data'}</pre>
+ <p>
+ Both these modes allow other return tuples
+ that you can find in the
+ <seealso marker="stdlib:gen_statem#Module:StateName/3">
+ reference manual.
+ </seealso>
+ These other return tuples can for example stop the machine,
+ execute state transition actions on the machine engine itself
+ and send replies.
+ </p>
+
+ <section>
+ <title>Choosing the Callback Mode</title>
+ <p>
+ The two
+ <seealso marker="#callback_modes">callback modes</seealso>
+ gives different possibilities
+ and restrictions, but one goal remains:
+ you want to handle all possible combinations of
+ events and states.
+ </p>
+ <p>
+ You can for example do this by focusing on one state at the time
+ and for every state ensure that all events are handled,
+ or the other way around focus on one event at the time
+ and ensure that it is handled in every state,
+ or mix these strategies.
+ </p>
+ <p>
+ With <c>state_functions</c> you are restricted to use
+ atom only states, and the <c>gen_statem</c> engine dispatches
+ on state name for you. This encourages the callback module
+ to gather the implementation of all event actions particular
+ to one state in the same place in the code
+ hence to focus on one state at the time.
+ </p>
+ <p>
+ This mode fits well when you have a regular state diagram
+ like the ones in this chapter that describes all events and actions
+ belonging to a state visually around that state,
+ and each state has its unique name.
+ </p>
+ <p>
+ With <c>handle_event_function</c> you are free to mix strategies
+ as you like because all events and states
+ are handled in the the same callback function.
+ </p>
+ <p>
+ This mode works equally well when you want to focus on
+ one event at the time or when you want to focus on
+ one state at the time, but the <c>handle_event/4</c> function
+ quickly grows too large to handle without introducing dispatching.
+ </p>
+ <p>
+ The mode enables the use of non-atom states for example
+ complex states or even hiearchical states.
+ If, for example, a state diagram is largely alike
+ for the client and for the server side of a protocol;
+ then you can have a state <c>{StateName,server}</c> or
+ <c>{StateName,client}</c> and since you do the dispatching
+ yourself you make <c>StateName</c> decide where in the code
+ to handle most events in the state.
+ The second element of the tuple is then used to select
+ whether to handle special client side or server side events.
+ </p>
+ </section>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Example</title>
+ <p>
+ This is an example starting off as equivalent to the the example in the
+ <seealso marker="fsm"><c>gen_fsm</c> behaviour</seealso>
+ description. In later chapters additions and tweaks are made
+ using features in <c>gen_statem</c> that <c>gen_fsm</c> does not have.
+ At the end of this section you can find the example again
+ with all the added features.
+ </p>
+ <p>
+ A door with a code lock can be viewed as a state machine.
+ Initially, the door is locked. Anytime someone presses a button,
+ this generates an event.
+ Depending on what buttons have been pressed before,
+ the sequence so far can be correct, incomplete, or wrong.
+ </p>
+ <p>
+ If it is correct, the door is unlocked for 10 seconds (10000 ms).
+ If it is incomplete, we wait for another button to be pressed. If
+ it is is wrong, we start all over,
+ waiting for a new button sequence.
+ </p>
+ <image file="../design_principles/code_lock.png">
+ <icaption>Code lock state diagram</icaption>
+ </image>
+ <p>
+ We can implement such a code lock state machine using
+ <c>gen_statem</c> with the following callback module:
+ </p>
+ <marker id="ex"></marker>
+ <code type="erl"><![CDATA[
+-module(code_lock).
+-behaviour(gen_statem).
+-define(NAME, code_lock).
+-define(CALLBACK_MODE, state_functions).
+
+-export([start_link/1]).
+-export([button/1]).
+-export([init/1,terminate/3,code_change/4]).
+-export([locked/3,open/3]).
+
+start_link(Code) ->
+ gen_statem:start_link({local,?NAME}, ?MODULE, Code, []).
+
+button(Digit) ->
+ gen_statem:cast(?NAME, {button,Digit}).
+
+
+init(Code) ->
+ do_lock(),
+ Data = #{code => Code, remaining => Code},
+ {?CALLBACK_MODE,locked,Data}.
+
+locked(
+ cast, {button,Digit},
+ #{code := Code, remaining := Remaining} = Data) ->
+ case Remaining of
+ [Digit] ->
+ do_unlock(),
+ {next_state,open,Data#{remaining := Code},10000};
+ [Digit|Rest] -> % Incomplete
+ {next_state,locked,Data#{remaining := Rest}};
+ _Wrong ->
+ {next_state,locked,Data#{remaining := Code}}
+ end.
+
+open(timeout, _, Data) ->
+ do_lock(),
+ {next_state,locked,Data};
+open(cast, {button,_}, Data) ->
+ do_lock(),
+ {next_state,locked,Data}.
+
+do_lock() ->
+ io:format("Lock~n", []).
+do_unlock() ->
+ io:format("Unlock~n", []).
+
+terminate(_Reason, State, _Data) ->
+ State =/= locked andalso do_lock(),
+ ok.
+code_change(_Vsn, State, Data, _Extra) ->
+ {?CALLBACK_MODE,State,Data}.
+ ]]></code>
+ <p>The code is explained in the next sections.</p>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Starting gen_statem</title>
+ <p>
+ In the example in the previous section, the <c>gen_statem</c> is
+ started by calling <c>code_lock:start_link(Code)</c>:
+ </p>
+ <code type="erl"><![CDATA[
+start_link(Code) ->
+ gen_statem:start_link({local,?NAME}, ?MODULE, Code, []).
+ ]]></code>
+ <p>
+ <c>start_link</c> calls the function
+ <seealso marker="stdlib:gen_statem#start_link/4">
+ <c>gen_statem:start_link/4</c>
+ </seealso>
+ which spawns and links to a new process; a <c>gen_statem</c>.
+ </p>
+ <list type="bulleted">
+ <item>
+ <p>
+ The first argument, <c>{local,?NAME}</c>, specifies
+ the name. In this case, the <c>gen_statem</c> is locally
+ registered as <c>code_lock</c> through the macro <c>?NAME</c>.
+ </p>
+ <p>
+ If the name is omitted, the <c>gen_statem</c> is not registered.
+ Instead its pid must be used. The name can also be given
+ as <c>{global,Name}</c>, in which case the <c>gen_statem</c> is
+ registered using
+ <seealso marker="kernel:global#register_name/2">
+ <c>global:register_name/2</c>.
+ </seealso>
+ </p>
+ </item>
+ <item>
+ <p>
+ The second argument, <c>?MODULE</c>, is the name of
+ the callback module, that is; the module where the callback
+ functions are located, which is this module.
+ </p>
+ <p>
+ The interface functions (<c>start_link/1</c> and <c>button/1</c>)
+ are located in the same module as the callback functions
+ (<c>init/1</c>, <c>locked/3</c>, and <c>open/3</c>).
+ It is normally good programming practice to have the client
+ side and the server side code contained in one module.
+ </p>
+ </item>
+ <item>
+ <p>
+ The third argument, <c>Code</c>, is a list of digits that
+ is the correct unlock code which is passsed
+ to the callback function <c>init/1</c>.
+ </p>
+ </item>
+ <item>
+ <p>
+ The fourth argument, <c>[]</c>, is a list of options. See the
+ <seealso marker="stdlib:gen_statem#start_link/3">
+ <c>gen_statem:start_link/3</c>
+ </seealso>
+ manual page for available options.
+ </p>
+ </item>
+ </list>
+ <p>
+ If name registration succeeds, the new <c>gen_statem</c> process
+ calls the callback function <c>code_lock:init(Code)</c>.
+ This function is expected to return <c>{CallbackMode,State,Data}</c>,
+ where
+ <seealso marker="#callback_modes">
+ <c>CallbackMode</c>
+ </seealso>
+ selects callback module state function mode, in this case
+ <seealso marker="stdlib:gen_statem#type-callback_mode">
+ <c>state_functions</c>
+ </seealso>
+ through the macro <c>?CALLBACK_MODE</c> that is; each state
+ has got its own handler function.
+ <c>State</c> is the initial state of the <c>gen_statem</c>,
+ in this case <c>locked</c>; assuming the door is locked to begin with.
+ <c>Data</c> is the internal server data of the <c>gen_statem</c>.
+ Here the server data is a <seealso marker="stdlib:maps">map</seealso>
+ with the key <c>code</c> that stores
+ the correct button sequence and the key <c>remaining</c>
+ that stores the remaining correct button sequence
+ (the same as the <c>code</c> to begin with).
+ </p>
+ <code type="erl"><![CDATA[
+init(Code) ->
+ do_lock(),
+ Data = #{code => Code, remaining => Code},
+ {?CALLBACK_MODE,locked,Data}.
+ ]]></code>
+ <p>
+ <seealso marker="stdlib:gen_statem#start_link/3">
+ <c>gen_statem:start_link</c>
+ </seealso>
+ is synchronous. It does not return until the <c>gen_statem</c>
+ has been initialized and is ready to receive events.
+ </p>
+ <p>
+ <seealso marker="stdlib:gen_statem#start_link/3">
+ <c>gen_statem:start_link</c>
+ </seealso>
+ must be used if the <c>gen_statem</c>
+ is part of a supervision tree, that is; started by a supervisor.
+ There is another function;
+ <seealso marker="stdlib:gen_statem#start/3">
+ <c>gen_statem:start</c>
+ </seealso>
+ to start a standalone <c>gen_statem</c>, that is;
+ a <c>gen_statem</c> that is not part of a supervision tree.
+ </p>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Events and Handling them</title>
+ <p>The function notifying the code lock about a button event is
+ implemented using
+ <seealso marker="stdlib:gen_statem#cast/2">
+ <c>gen_statem:cast/2</c>:
+ </seealso>
+ </p>
+ <code type="erl"><![CDATA[
+button(Digit) ->
+ gen_statem:cast(?NAME, {button,Digit}).
+ ]]></code>
+ <p>
+ The first argument is the name of the <c>gen_statem</c> and must
+ agree with the name used to start it so therefore we use the
+ same macro <c>?NAME</c> as when starting.
+ <c>{button,Digit}</c> is the actual event content.
+ </p>
+ <p>
+ The event is made into a message and sent to the <c>gen_statem</c>.
+ When the event is received, the <c>gen_statem</c> calls
+ <c>StateName(cast, Event, Data)</c>, which is expected to
+ return a tuple <c>{next_state,NewStateName,NewData}</c>.
+ <c>StateName</c> is the name of the current state and
+ <c>NewStateName</c> is the name of the next state to go to.
+ <c>NewData</c> is a new value for the server data of
+ the <c>gen_statem</c>.
+ </p>
+ <code type="erl"><![CDATA[
+locked(
+ cast, {button,Digit},
+ #{code := Code, remaining := Remaining} = Data) ->
+ case Remaining of
+ [Digit] -> % Complete
+ do_unlock(),
+ {next_state,open,Data#{remaining := Code},10000};
+ [Digit|Rest] -> % Incomplete
+ {next_state,locked,Data#{remaining := Rest}};
+ [_|_] -> % Wrong
+ {next_state,locked,Data#{remaining := Code}}
+ end.
+
+open(timeout, _, Data) ->
+ do_lock(),
+ {next_state,locked,Data};
+open(cast, {button,_}, Data) ->
+ do_lock(),
+ {next_state,locked,Data}.
+ ]]></code>
+ <p>
+ If the door is locked and a button is pressed, the pressed
+ button is compared with the next correct button and,
+ depending on the result, the door is either unlocked
+ and the <c>gen_statem</c> goes to state <c>open</c>,
+ or the door remains in state <c>locked</c>.
+ </p>
+ <p>
+ If the pressed button is incorrect the server data
+ restarts from the start of the code sequence.
+ </p>
+ <p>
+ In state <c>open</c> any button locks the door since
+ any event cancels the event timer so we will not get
+ a timeout event after a button event.
+ </p>
+ </section>
+
+ <section>
+ <title>Event Time-Outs</title>
+ <p>
+ When a correct code has been given, the door is unlocked and
+ the following tuple is returned from <c>locked/2</c>:
+ </p>
+ <code type="erl"><![CDATA[
+{next_state,open,Data#{remaining := Code},10000};
+ ]]></code>
+ <p>
+ 10000 is a time-out value in milliseconds.
+ After this time, that is; 10 seconds, a time-out occurs.
+ Then, <c>StateName(timeout, 10000, Data)</c> is called.
+ The time-out occurs when the door has been in state <c>open</c>
+ for 10 seconds. After that the door is locked again:
+ </p>
+ <code type="erl"><![CDATA[
+open(timeout, _, Data) ->
+ do_lock(),
+ {next_state,locked,Data};
+ ]]></code>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>All State Events</title>
+ <p>
+ Sometimes an event can arrive in any state of the <c>gen_statem</c>.
+ It is convenient to handle these in a common state handler function
+ that all state functions call for events not specific to the state.
+ </p>
+ <p>
+ Let's introduce a <c>code_length/0</c> function that returns
+ the length of the correct code
+ (that should not be sensitive to reveal...).
+ We'll dispatch all events that are not state specific
+ to the common function <c>handle_event/3</c>.
+ </p>
+ <code type="erl"><![CDATA[
+...
+-export([button/1,code_length/0]).
+...
+
+code_length() ->
+ gen_statem:call(?NAME, code_length).
+
+...
+locked(...) -> ... ;
+locked(EventType, EventContent, Data) ->
+ handle_event(EventType, EventContent, Data).
+
+...
+open(...) -> ... ;
+open(EventType, EventContent, Data) ->
+ handle_event(EventType, EventContent, Data).
+
+handle_event({call,From}, code_length, #{code := Code} = Data) ->
+ {keep_state,Data,[{reply,From,length(Code)}]}.
+ ]]></code>
+ <p>
+ This example uses
+ <seealso marker="stdlib:gen_statem#call/2">
+ <c>gen_statem:call/2</c>
+ </seealso>
+ which waits for a reply from the server.
+ The reply is sent with a <c>{reply,From,Reply}</c> tuple
+ in an action list in the <c>{keep_state,...}</c> tuple
+ that retains the current state.
+ </p>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>One Event Handler</title>
+ <p>
+ If you use the mode <c>handle_event_function</c>
+ all events are handled in <c>handle_event/4</c> and we
+ may (but do not have to) use an event-centered approach
+ where we dispatch on event first and then state:
+ </p>
+ <code type="erl"><![CDATA[
+...
+-define(CALLBACK_MODE, state_functions).
+
+...
+-export([handle_event/4]).
+
+...
+
+handle_event(cast, {button,Digit}, State, #{code := Code} = Data) ->
+ case State of
+ locked ->
+ case maps:get(remaining, Data) of
+ [Digit] -> % Complete
+ do_unlock(),
+ {next_state,open,Data#{remaining := Code},10000};
+ [Digit|Rest] -> % Incomplete
+ {keep_state,Data#{remaining := Rest}};
+ [_|_] -> % Wrong
+ {keep_state,Data#{remaining := Code}}
+ end;
+ open ->
+ do_lock(),
+ {next_state,locked,Data}
+ end;
+handle_event(timeout, _, open, Data) ->
+ do_lock(),
+ {next_state,locked,Data}.
+
+...
+ ]]></code>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Stopping</title>
+
+ <section>
+ <title>In a Supervision Tree</title>
+ <p>
+ If the <c>gen_statem</c> is part of a supervision tree,
+ no stop function is needed.
+ The <c>gen_statem</c> is automatically terminated by its supervisor.
+ Exactly how this is done is defined by a
+ <seealso marker="sup_princ#shutdown">shutdown strategy</seealso>
+ set in the supervisor.
+ </p>
+ <p>
+ If it is necessary to clean up before termination, the shutdown
+ strategy must be a time-out value and the <c>gen_statem</c> must
+ in the <c>init/1</c> function set itself to trap exit signals
+ by calling
+ <seealso marker="erts:erlang#process_flag/2">
+ <c>process_flag(trap_exit, true)</c>.
+ </seealso>
+ When ordered to shutdown, the <c>gen_statem</c> then calls
+ the callback function
+ <c>terminate(shutdown, State, Data)</c>:
+ </p>
+ <code type="erl"><![CDATA[
+init(Args) ->
+ process_flag(trap_exit, true),
+ do_lock(),
+ ...
+ ]]></code>
+ <p>
+ In this example we let the <c>terminate/3</c> function
+ lock the door if it is open so we do not accidentally leave the door
+ open when the supervision tree terminates.
+ </p>
+ <code type="erl"><![CDATA[
+terminate(_Reason, State, _Data) ->
+ State =/= locked andalso do_lock(),
+ ok.
+ ]]></code>
+ </section>
+
+ <section>
+ <title>Standalone gen_statem</title>
+ <p>
+ If the <c>gen_statem</c> is not part of a supervision tree,
+ it can be stopped using
+ <seealso marker="stdlib:gen_statem#stop/1">
+ <c>gen_statem:stop</c>,
+ </seealso>
+ preferably through an API function:
+ </p>
+ <code type="erl"><![CDATA[
+...
+-export([start_link/1,stop/0]).
+
+...
+stop() ->
+ gen_statem:stop(?NAME).
+ ]]></code>
+ <p>
+ This makes the <c>gen_statem</c> call the <c>terminate/3</c>
+ callback function just like for a supervised server
+ and waits for the process to terminate.
+ </p>
+ </section>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Actions</title>
+ <p>
+ In the first chapters we mentioned actions as a part of
+ the general state machine model, and these actions
+ are implemented with the code the <c>gen_statem</c>
+ callback module executes in an event handling
+ callback function before returning
+ to the <c>gen_statem</c> engine.
+ </p>
+ <p>
+ There are more specific state transition actions
+ that a callback function can order the <c>gen_statem</c>
+ engine to do after the callback function return.
+ These are ordered by returning a list of
+ <seealso marker="stdlib:gen_statem#type-action">
+ actions
+ </seealso>
+ in the
+ <seealso marker="stdlib:gen_statem#type-state_function_result">
+ return tuple
+ </seealso>
+ from the
+ <seealso marker="stdlib:gen_statem#Module:StateName/3">
+ callback function.
+ </seealso>
+ These state transition actions affect the <c>gen_statem</c>
+ engine itself. They can:
+ </p>
+ <list type="bulleted">
+ <item>Postpone the current event.</item>
+ <item>Hibernate the <c>gen_statem</c>.</item>
+ <item>Start an event timeout.</item>
+ <item>Reply to a caller.</item>
+ <item>Generate the next event to handle.</item>
+ </list>
+ <p>
+ We have mentioned the event timeout
+ and replying to a caller in the example above.
+ An example of event postponing comes in later in this chapter.
+ See the
+ <seealso marker="stdlib:gen_statem#type-action">
+ reference manual
+ </seealso>
+ for details. You can for example actually reply to several callers
+ and generate multiple next events to handle.
+ </p>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Event Types</title>
+ <p>
+ So far we have mentioned a few
+ <seealso marker="stdlib:gen_statem#type-event_type">
+ event types.
+ </seealso>
+ Events of all types are handled in the same callback function,
+ for a given state, and the function gets
+ <c>EventType</c> and <c>EventContent</c> as arguments.
+ </p>
+ <p>
+ Here is the complete list of event types and where
+ they come from:
+ </p>
+ <taglist>
+ <tag><c>cast</c></tag>
+ <item>
+ Generated by
+ <seealso marker="stdlib:gen_statem#cast/2">
+ <c>gen_statem:cast</c>.
+ </seealso>
+ </item>
+ <tag><c>{call,From}</c></tag>
+ <item>
+ Generated by
+ <seealso marker="stdlib:gen_statem#call/2">
+ <c>gen_statem:call</c>
+ </seealso>
+ where <c>From</c> is the reply address to use
+ when replying either through the state transition action
+ <c>{reply,From,Msg}</c> or by calling
+ <seealso marker="stdlib:gen_statem#reply/1">
+ <c>gen_statem:reply</c>.
+ </seealso>
+ </item>
+ <tag><c>info</c></tag>
+ <item>
+ Generated by any regular process message sent to
+ the <c>gen_statem</c> process.
+ </item>
+ <tag><c>timeout</c></tag>
+ <item>
+ Generated by the state transition action
+ <c>{timeout,Time,EventContent}</c> (or its short form <c>Time</c>)
+ timer timing out.
+ </item>
+ <tag><c>internal</c></tag>
+ <item>
+ Generated by the state transition action
+ <c>{next_event,internal,EventContent}</c>.
+ In fact all event types above can be generated using
+ <c>{next_event,EventType,EventContent}</c>.
+ </item>
+ </taglist>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>State Timeouts</title>
+ <p>
+ The timeout event generated by the state transition action
+ <c>{timeout,Time,EventContent}</c> is an event timeout,
+ that is; if an event arrives the timer is cancelled.
+ You get either an event or a timeout but not both.
+ </p>
+ <p>
+ Often you want a timer to not be cancelled by any event
+ or you want to start a timer in one state and respond
+ to the timeout in another. This can be accomplished
+ with a regular erlang timer:
+ <seealso marker="erts:erlang#start_timer/4">
+ <c>erlang:start_timer</c>.
+ </seealso>
+ </p>
+ <p>
+ Looking at the example in this chapter so far; using the
+ <c>gen_statem</c> event timer has the consequence that
+ if a button event is generated while in the <c>open</c> state,
+ the timeout is cancelled and the button event is delivered.
+ Therefore we chose to lock the door if this happended.
+ </p>
+ <p>
+ Suppose we do not want a button to lock the door,
+ instead we want to ignore button events in the <c>open</c> state.
+ Then we start a timer when entering the <c>open</c> state
+ and wait for it to expire while ignoring button events:
+ </p>
+ <code type="erl"><![CDATA[
+...
+locked(
+ cast, {button,Digit},
+ #{code := Code, remaining := Remaining} = Data) ->
+ case Remaining of
+ [Digit] ->
+ do_unlock(),
+ Tref = erlang:start_timer(10000, self(), lock),
+ {next_state,open,Data#{remaining := Code, timer := Tref}};
+...
+
+open(info, {timeout,Tref,lock}, #{timer := Tref} = Data) ->
+ do_lock(),
+ {next_state,locked,Data};
+open(cast, {button,_}, Data) ->
+ {keep_state,Data};
+...
+ ]]></code>
+ <p>
+ If you need to cancel a timer due to some other event you can use
+ <seealso marker="erts:erlang#cancel_timer/2">
+ <c>erlang:cancel_timer(Tref)</c>.
+ </seealso>
+ Note that a timeout message can not arrive after this,
+ unless you have postponed it (see the next section) before,
+ so make sure you do not accidentally postpone such messages.
+ </p>
+ <p>
+ Another way to cancel a timer is to not cancel it,
+ but instead to ignore it if it arrives in a state
+ where it is known to be late.
+ </p>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Postponing Events</title>
+ <p>
+ If you want to ignore a particular event in the current state
+ and handle it in a future state, you can postpone the event.
+ A postponed event is retried after the state has
+ changed i.e <c>OldState =/= NewState</c>.
+ </p>
+ <p>
+ Postponing is ordered by the state transition
+ <seealso marker="stdlib:gen_statem#type-action">
+ action
+ </seealso>
+ <c>postpone</c>.
+ </p>
+ <p>
+ In this example, instead of ignoring button events
+ while in the <c>open</c> state we can postpone them
+ and they will be queued and later handled in the <c>locked</c> state:
+ </p>
+ <code type="erl"><![CDATA[
+...
+open(cast, {button,_}, Data) ->
+ {keep_state,Data,[postpone]};
+...
+ ]]></code>
+ <p>
+ The fact that a postponed event is only retried after a state change
+ translates into a requirement on the event and state space:
+ if you have a choice between storing a state data item
+ in the <c>State</c> or in the <c>Data</c>;
+ should a change in the item value affect which events that
+ are handled, then this item ought to be part of the state.
+ </p>
+ <p>
+ What you want to avoid is that you maybe much later decide
+ to postpone an event in one state and by misfortune it is never retried
+ because the code only changes the <c>Data</c> but not the <c>State</c>.
+ </p>
+
+ <section>
+ <title>Fuzzy State Diagrams</title>
+ <p>
+ It is not uncommon that a state diagram does not specify
+ how to handle events that are not illustrated
+ in a particular state in the diagram.
+ Hopefully this is described in an associated text
+ or from the context.
+ </p>
+ <p>
+ Possible actions may be; ignore as in drop the event
+ (maybe log it) or deal with the event in some other state
+ as in postpone it.
+ </p>
+ </section>
+
+ <section>
+ <title>Selective Receive</title>
+ <p>
+ Erlang's selective receive statement is often used to
+ describe simple state machine examples in straightforward
+ Erlang code. Here is a possible implementation of
+ the first example:
+ </p>
+ <code type="erl"><![CDATA[
+-module(code_lock).
+-define(NAME, code_lock_1).
+-export([start_link/1,button/1]).
+
+start_link(Code) ->
+ spawn(
+ fun () ->
+ true = register(?NAME, self()),
+ do_lock(),
+ locked(Code, Code)
+ end).
+
+button(Digit) ->
+ ?NAME ! {button,Digit}.
+
+locked(Code, [Digit|Remaining]) ->
+ receive
+ {button,Digit} when Remaining =:= [] ->
+ do_unlock(),
+ open(Code);
+ {button,Digit} ->
+ locked(Code, Remaining);
+ {button,_} ->
+ locked(Code, Code)
+ end.
+
+open(Code) ->
+ receive
+ after 10000 ->
+ do_lock(),
+ locked(Code, Code)
+ end.
+
+do_lock() ->
+ io:format("Locked~n", []).
+do_unlock() ->
+ io:format("Open~n", []).
+ ]]></code>
+ <p>
+ The selective receive in this case causes <c>open</c>
+ to implicitly postpone any events to the <c>locked</c> state.
+ </p>
+ <p>
+ A selective receive can not be used from a <c>gen_statem</c>
+ behaviour just as for any <c>gen_*</c> behavior
+ since the receive statement is within the <c>gen_*</c> engine itself.
+ It has to be there because all
+ <seealso marker="stdlib:sys"><c>sys</c></seealso>
+ compatible behaviours must respond to system messages and therefore
+ do that in their engine receive loop,
+ passing non-system messages to the callback module.
+ </p>
+ <p>
+ The state transition
+ <seealso marker="stdlib:gen_statem#type-action">
+ action
+ </seealso>
+ <c>postpone</c> is designed to be able to model
+ selective receives. A selective receive implicitly postpones
+ any not received events, but the <c>postpone</c>
+ state transition action explicitly postpones one received event.
+ </p>
+ <p>
+ Other than that both mechanisms have got the same theoretical
+ time and memory complexity, while the selective receive
+ language construct has got smaller constant factors.
+ </p>
+ </section>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Self Generated Events</title>
+ <p>
+ It may be beneficial in some cases to be able to generate events
+ to your own state machine.
+ This can be done with the state transition
+ <seealso marker="stdlib:gen_statem#type-action">
+ action
+ </seealso>
+ <c>{next_event,EventType,EventContent}</c>.
+ </p>
+ <p>
+ You can generate events of any existing
+ <seealso marker="stdlib:gen_statem#type-action">
+ type,
+ </seealso>
+ but the <c>internal</c> type can only be generated through the
+ <c>next_event</c> action and hence can not come from an external source,
+ so you can be certain that an <c>internal</c> event is an event
+ from your state machine to itself.
+ </p>
+ <p>
+ One example of using self generated events may be when you have
+ a state machine specification that uses state entry actions.
+ That you could code using a dedicated function
+ to do the state transition. But if you want that code to be
+ visible besides the other state logic you can insert
+ an <c>internal</c> event that does the entry actions.
+ This has the same unfortunate consequence as using
+ state transition functions that everywhere you go to
+ the state in question you will have to explicitly
+ insert the <c>internal</c> event
+ or use state transition function.
+ </p>
+ <p>
+ Here is an implementation of entry actions
+ using <c>internal</c> events with content <c>enter</c>
+ utilizing a helper function <c>enter/3</c> for state entry:
+ </p>
+ <code type="erl"><![CDATA[
+...
+-define(CALLBACK_MODE, state_functions).
+
+...
+
+init(Code) ->
+ process_flag(trap_exit, true),
+ Data = #{code => Code},
+ enter(?CALLBACK_MODE, locked, Data).
+
+...
+
+locked(internal, enter, _Data) ->
+ do_lock(),
+ {keep_state,Data#{remaining => Code}};
+locked(
+ cast, {button,Digit},
+ #{code := Code, remaining := Remaining} = Data) ->
+ case Remaining of
+ [Digit] ->
+ enter(next_state, open, Data);
+...
+
+open(internal, enter, _Data) ->
+ Tref = erlang:start_timer(10000, self(), lock),
+ do_unlock(),
+ {keep_state,Data#{timer => Tref}};
+open(info, {timeout,Tref,lock}, #{timer := Tref} = Data) ->
+ enter(next_state, locked, Data);
+...
+
+enter(Tag, State, Data) ->
+ {Tag,State,Data,[{next_event,internal,enter}]}.
+ ]]></code>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Example Revisited</title>
+ <p>
+ Here is the example after all mentioned modifications
+ and some more utilizing the entry actions,
+ which deserves a new state diagram:
+ </p>
+ <image file="../design_principles/code_lock_2.png">
+ <icaption>Code lock state diagram revisited</icaption>
+ </image>
+ <p>
+ Note that this state diagram does not specify how to handle
+ a button event in the state <c>open</c>, so you will have to
+ read some other place that is here that unspecified events
+ shall be ignored as in not consumed but handled in some other state.
+ Nor does it show that the <c>code_length/0</c> call shall be
+ handled in every state.
+ </p>
+
+ <section>
+ <title>Callback Mode: state_functions</title>
+ <p>
+ Using state functions:
+ </p>
+ <code type="erl"><![CDATA[
+-module(code_lock).
+-behaviour(gen_statem).
+-define(NAME, code_lock_2).
+-define(CALLBACK_MODE, state_functions).
+
+-export([start_link/1,stop/0]).
+-export([button/1,code_length/0]).
+-export([init/1,terminate/3,code_change/4]).
+-export([locked/3,open/3]).
+
+start_link(Code) ->
+ gen_statem:start_link({local,?NAME}, ?MODULE, Code, []).
+stop() ->
+ gen_statem:stop(?NAME).
+
+button(Digit) ->
+ gen_statem:cast(?NAME, {button,Digit}).
+code_length() ->
+ gen_statem:call(?NAME, code_length).
+
+init(Code) ->
+ process_flag(trap_exit, true),
+ Data = #{code => Code},
+ enter(?CALLBACK_MODE, locked, Data).
+
+locked(internal, enter, #{code := Code} = Data) ->
+ do_lock(),
+ {keep_state,Data#{remaining => Code}};
+locked(
+ cast, {button,Digit},
+ #{code := Code, remaining := Remaining} = Data) ->
+ case Remaining of
+ [Digit] -> % Complete
+ enter(next_state, open, Data);
+ [Digit|Rest] -> % Incomplete
+ {keep_state,Data#{remaining := Rest}};
+ [_|_] -> % Wrong
+ {keep_state,Data#{remaining := Code}}
+ end;
+locked(EventType, EventContent, Data) ->
+ handle_event(EventType, EventContent, Data).
+
+open(internal, enter, Data) ->
+ Tref = erlang:start_timer(10000, self(), lock),
+ do_unlock(),
+ {keep_state,Data#{timer => Tref}};
+open(info, {timeout,Tref,lock}, #{timer := Tref} = Data) ->
+ enter(next_state, locked, Data);
+open(cast, {button,_}, _) ->
+ {keep_state_and_data,[postpone]};
+open(EventType, EventContent, Data) ->
+ handle_event(EventType, EventContent, Data).
+
+handle_event({call,From}, code_length, #{code := Code}) ->
+ {keep_state_and_data,[{reply,From,length(Code)}]}.
+enter(Tag, State, Data) ->
+ {Tag,State,Data,[{next_event,internal,enter}]}.
+
+do_lock() ->
+ io:format("Locked~n", []).
+do_unlock() ->
+ io:format("Open~n", []).
+
+terminate(_Reason, State, _Data) ->
+ State =/= locked andalso do_lock(),
+ ok.
+code_change(_Vsn, State, Data, _Extra) ->
+ {?CALLBACK_MODE,State,Data}.
+ ]]></code>
+ </section>
+
+ <section>
+ <title>Callback Mode: handle_event_function</title>
+ <p>
+ What to change to use one <c>handle_event/4</c> function.
+ Here a clean first-dispatch-on-event approach
+ does not work that well due to the generated
+ entry actions:
+ </p>
+ <code type="erl"><![CDATA[
+...
+-define(CALLBACK_MODE, handle_event_function).
+
+...
+-export([handle_event/4]).
+
+...
+
+%% State: locked
+handle_event(internal, enter, locked, #{code := Code} = Data) ->
+ do_lock(),
+ {keep_state,Data#{remaining => Code}};
+handle_event(
+ cast, {button,Digit}, locked,
+ #{code := Code, remaining := Remaining} = Data) ->
+ case Remaining of
+ [Digit] -> % Complete
+ enter(next_state, open, Data);
+ [Digit|Rest] -> % Incomplete
+ {keep_state,Data#{remaining := Rest}};
+ [_|_] -> % Wrong
+ {keep_state,Data#{remaining := Code}}
+ end;
+%%
+%% State: open
+handle_event(internal, enter, open, Data) ->
+ Tref = erlang:start_timer(10000, self(), lock),
+ do_unlock(),
+ {keep_state,Data#{timer => Tref}};
+handle_event(info, {timeout,Tref,lock}, open, #{timer := Tref} = Data) ->
+ enter(next_state, locked, Data);
+handle_event(cast, {button,_}, open, _) ->
+ {keep_state_and_data,[postpone]};
+%%
+%% Any state
+handle_event({call,From}, code_length, _State, #{code := Code}) ->
+ {keep_state_and_data,[{reply,From,length(Code)}]}.
+
+...
+ ]]></code>
+ </section>
+ <p>
+ Note that postponing buttons from the <c>locked</c> state
+ to the <c>open</c> state feels like the wrong thing to do
+ for a code lock, but it at least illustrates event postponing.
+ </p>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Filter the State</title>
+ <p>
+ The example servers so far in this chapter will for example
+ when killed by an exit signal or due to an internal error
+ print out the full internal state in the error log.
+ This state contains both the code lock code
+ and which digits that remains to unlock.
+ </p>
+ <p>
+ This state data can be regarded as sensitive,
+ and maybe not what you want in the error log
+ because of something unpredictable happening.
+ </p>
+ <p>
+ Another reason to filter the state can be
+ that the state is too big to print out since it fills
+ the error log with uninteresting details.
+ </p>
+ <p>
+ To avoid this you can format the internal state
+ that gets in the error log and gets returned from
+ <seealso marker="stdlib:sys#get_status/1">
+ <c>sys:get_status/1,2</c>
+ </seealso>
+ by implementing the
+ <seealso marker="stdlib:gen_statem#Module:format_status/2">
+ <c>Module:format_status/2</c>
+ </seealso>
+ function, for example like this:
+ </p>
+ <code type="erl"><![CDATA[
+...
+-export([init/1,terminate/3,code_change/4,format_status/2]).
+...
+
+format_status(Opt, [_PDict,State,Data]) ->
+ StateData =
+ {State,
+ maps:filter(
+ fun (code, _) -> false;
+ (remaining, _) -> false;
+ (_, _) -> true
+ end,
+ Data)},
+ case Opt of
+ terminate ->
+ StateData;
+ normal ->
+ [{data,[{"State",StateData}]}]
+ end.
+ ]]></code>
+ <p>
+ It is not mandatory to implement a
+ <seealso marker="stdlib:gen_statem#Module:format_status/2">
+ <c>Module:format_status/2</c>
+ </seealso>
+ function. If you do not a default implementation is used that
+ does the same as this example function without filtering
+ the <c>Data</c> term that is: <c>StateData = {State,Data}</c>.
+ </p>
+ </section>
+
+<!-- =================================================================== -->
+
+ <section>
+ <title>Complex State</title>
+ <p>
+ The callback mode
+ <seealso marker="stdlib:gen_statem#type-callback_mode">
+ <c>handle_event_function</c>
+ </seealso>
+ enables using a non-atom state as described in
+ <seealso marker="#callback_modes">
+ Callback Modes,
+ </seealso>
+ for example a complex state term like a tuple.
+ </p>
+ <p>
+ One reason to use this is when you have
+ a state item that affects the event handling
+ in particular when combining that with postponing events.
+ Let us complicate the previous example
+ by introducing a configurable lock button
+ (this is the state item in question)
+ that in the <c>open</c> state immediately locks the door,
+ and an API function <c>set_lock_button/1</c> to set the lock button.
+ </p>
+ <p>
+ Suppose now that we call <c>set_lock_button</c>
+ while the door is open,
+ and have already postponed a button event
+ that up until now was not the lock button;
+ the sensible thing might be to say that
+ the button was pressed too early so it should
+ not be recognized as the lock button,
+ but then it might be surprising that a button event
+ that now is the lock button event arrives (as retried postponed)
+ immediately after the state transits to <c>locked</c>.
+ </p>
+ <p>
+ So let us make the <c>button/1</c> function synchronous
+ by using <c>gen_statem:call</c>,
+ and still postpone its events in the <c>open</c> state.
+ Then a call to <c>button/1</c> during the <c>open</c>
+ state will not return until the state transits to <c>locked</c>
+ since it is there the event is handled and the reply is sent.
+ </p>
+ <p>
+ If now one process calls <c>set_lock_button/1</c>
+ to change the lock button while some other process
+ hangs in <c>button/1</c> with the new lock button
+ it could be expected that the hanging lock button call
+ immediately takes effect and locks the lock.
+ Therefore we make the current lock button a part of the state
+ so when we change the lock button the state will change
+ and all postponed events will be retried.
+ </p>
+ <p>
+ We define the state as <c>{StateName,LockButton}</c>
+ where <c>StateName</c> is as before
+ and <c>LockButton</c> is the current lock button:
+ </p>
+ <code type="erl"><![CDATA[
+-module(code_lock).
+-behaviour(gen_statem).
+-define(NAME, code_lock_3).
+-define(CALLBACK_MODE, handle_event_function).
+
+-export([start_link/2,stop/0]).
+-export([button/1,code_length/0,set_lock_button/1]).
+-export([init/1,terminate/3,code_change/4,format_status/2]).
+-export([handle_event/4]).
+
+start_link(Code, LockButton) ->
+ gen_statem:start_link(
+ {local,?NAME}, ?MODULE, {Code,LockButton}, []).
+stop() ->
+ gen_statem:stop(?NAME).
+
+button(Digit) ->
+ gen_statem:call(?NAME, {button,Digit}).
+code_length() ->
+ gen_statem:call(?NAME, code_length).
+set_lock_button(LockButton) ->
+ gen_statem:call(?NAME, {set_lock_button,LockButton}).
+
+init({Code,LockButton}) ->
+ process_flag(trap_exit, true),
+ Data = #{code => Code, remaining => undefined, timer => undefined},
+ enter(?CALLBACK_MODE, {locked,LockButton}, Data, []).
+
+handle_event(
+ {call,From}, {set_lock_button,NewLockButton},
+ {StateName,OldLockButton}, Data) ->
+ {next_state,{StateName,NewLockButton},Data,
+ [{reply,From,OldLockButton}]};
+handle_event(
+ {call,From}, code_length,
+ {_StateName,_LockButton}, #{code := Code}) ->
+ {keep_state_and_data,
+ [{reply,From,length(Code)}]};
+handle_event(
+ EventType, EventContent,
+ {locked,LockButton}, #{code := Code, remaining := Remaining} = Data) ->
+ case {EventType,EventContent} of
+ {internal,enter} ->
+ do_lock(),
+ {keep_state,Data#{remaining := Code}};
+ {{call,From},{button,Digit}} ->
+ case Remaining of
+ [Digit] -> % Complete
+ next_state(
+ {open,LockButton}, Data,
+ [{reply,From,ok}]);
+ [Digit|Rest] -> % Incomplete
+ {keep_state,Data#{remaining := Rest},
+ [{reply,From,ok}]};
+ [_|_] -> % Wrong
+ {keep_state,Data#{remaining := Code},
+ [{reply,From,ok}]}
+ end
+ end;
+handle_event(
+ EventType, EventContent,
+ {open,LockButton}, #{timer := Timer} = Data) ->
+ case {EventType,EventContent} of
+ {internal,enter} ->
+ Tref = erlang:start_timer(10000, self(), lock),
+ do_unlock(),
+ {keep_state,Data#{timer := Tref}};
+ {info,{timeout,Timer,lock}} ->
+ next_state({locked,LockButton}, Data, []);
+ {{call,From},{button,Digit}} ->
+ if
+ Digit =:= LockButton ->
+ erlang:cancel_timer(Timer),
+ next_state(
+ {locked,LockButton}, Data,
+ [{reply,From,locked}]);
+ true ->
+ {keep_state_and_data,
+ [postpone]}
+ end
+ end.
+
+next_state(State, Data, Actions) ->
+ enter(next_state, State, Data, Actions).
+enter(Tag, State, Data, Actions) ->
+ {Tag,State,Data,[{next_event,internal,enter}|Actions]}.
+
+do_lock() ->
+ io:format("Locked~n", []).
+do_unlock() ->
+ io:format("Open~n", []).
+
+terminate(_Reason, State, _Data) ->
+ State =/= locked andalso do_lock(),
+ ok.
+code_change(_Vsn, State, Data, _Extra) ->
+ {?CALLBACK_MODE,State,Data}.
+format_status(Opt, [_PDict,State,Data]) ->
+ StateData =
+ {State,
+ maps:filter(
+ fun (code, _) -> false;
+ (remaining, _) -> false;
+ (_, _) -> true
+ end,
+ Data)},
+ case Opt of
+ terminate ->
+ StateData;
+ normal ->
+ [{data,[{"State",StateData}]}]
+ end.
+ ]]></code>
+ <p>
+ It may be an ill-fitting model for a physical code lock
+ that the <c>button/1</c> call might hang until the lock
+ is locked. But for an API in general it is really not
+ that strange.
+ </p>
+ </section>
+
+</chapter>
diff --git a/system/doc/design_principles/sup_princ.xml b/system/doc/design_principles/sup_princ.xml
index 7408a34442..a77b3964fc 100644
--- a/system/doc/design_principles/sup_princ.xml
+++ b/system/doc/design_principles/sup_princ.xml
@@ -213,6 +213,7 @@ child_spec() = #{id => child_id(), % mandatory
<item><c>supervisor:start_link</c></item>
<item><c>gen_server:start_link</c></item>
<item><c>gen_fsm:start_link</c></item>
+ <item><c>gen_statem:start_link</c></item>
<item><c>gen_event:start_link</c></item>
<item>A function compliant with these functions. For details,
see the <c>supervisor(3)</c> manual page.</item>
@@ -276,7 +277,8 @@ child_spec() = #{id => child_id(), % mandatory
<p><c>modules</c> are to be a list with one element
<c>[Module]</c>, where <c>Module</c> is the name of
the callback module, if the child process is a supervisor,
- gen_server or gen_fsm. If the child process is a gen_event,
+ gen_server, gen_fsm or gen_statem.
+ If the child process is a gen_event,
the value shall be <c>dynamic</c>.</p>
<p>This information is used by the release handler during
upgrades and downgrades, see
@@ -400,8 +402,8 @@ supervisor:delete_child(Sup, Id)</code>
restarts.</p>
</section>
- <marker id="simple"/>
<section>
+ <marker id="simple"/>
<title>Simplified one_for_one Supervisors</title>
<p>A supervisor with restart strategy <c>simple_one_for_one</c> is
a simplified <c>one_for_one</c> supervisor, where all child
diff --git a/system/doc/design_principles/xmlfiles.mk b/system/doc/design_principles/xmlfiles.mk
index 9c3836c8ac..e476255d62 100644
--- a/system/doc/design_principles/xmlfiles.mk
+++ b/system/doc/design_principles/xmlfiles.mk
@@ -25,6 +25,7 @@ DESIGN_PRINCIPLES_CHAPTER_FILES = \
distributed_applications.xml \
events.xml \
fsm.xml \
+ statem.xml \
gen_server_concepts.xml \
included_applications.xml \
release_handling.xml \
diff --git a/system/doc/reference_manual/modules.xml b/system/doc/reference_manual/modules.xml
index 5f2ac2a67d..96968b547e 100644
--- a/system/doc/reference_manual/modules.xml
+++ b/system/doc/reference_manual/modules.xml
@@ -4,7 +4,7 @@
<chapter>
<header>
<copyright>
- <year>2003</year><year>2015</year>
+ <year>2003</year><year>2016</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -144,6 +144,7 @@ fact(0) -> % |
<list type="bulleted">
<item><c>gen_server</c></item>
<item><c>gen_fsm</c></item>
+ <item><c>gen_statem</c></item>
<item><c>gen_event</c></item>
<item><c>supervisor</c></item>
</list>