diff options
Diffstat (limited to 'system/doc')
111 files changed, 1767 insertions, 189 deletions
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 29df484279..937b3e28c8 100644 --- a/system/doc/design_principles/Makefile +++ b/system/doc/design_principles/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1997-2012. 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. @@ -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/applications.xml b/system/doc/design_principles/applications.xml index 4d73e0fc66..0a1b65ea8e 100644 --- a/system/doc/design_principles/applications.xml +++ b/system/doc/design_principles/applications.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2014</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/design_principles/appup_cookbook.xml b/system/doc/design_principles/appup_cookbook.xml index 31335197d7..4f23c42c59 100644 --- a/system/doc/design_principles/appup_cookbook.xml +++ b/system/doc/design_principles/appup_cookbook.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2014</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -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/book.xml b/system/doc/design_principles/book.xml index 663551df2f..a734f1d1e4 100644 --- a/system/doc/design_principles/book.xml +++ b/system/doc/design_principles/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/design_principles/code_lock.dia b/system/doc/design_principles/code_lock.dia Binary files differnew file mode 100644 index 0000000000..8e6ff8a898 --- /dev/null +++ b/system/doc/design_principles/code_lock.dia diff --git a/system/doc/design_principles/code_lock.png b/system/doc/design_principles/code_lock.png Binary files differnew file mode 100644 index 0000000000..745fd91920 --- /dev/null +++ b/system/doc/design_principles/code_lock.png diff --git a/system/doc/design_principles/code_lock_2.dia b/system/doc/design_principles/code_lock_2.dia Binary files differnew file mode 100644 index 0000000000..142909a2f5 --- /dev/null +++ b/system/doc/design_principles/code_lock_2.dia diff --git a/system/doc/design_principles/code_lock_2.png b/system/doc/design_principles/code_lock_2.png Binary files differnew file mode 100644 index 0000000000..ecf7b0d799 --- /dev/null +++ b/system/doc/design_principles/code_lock_2.png diff --git a/system/doc/design_principles/des_princ.xml b/system/doc/design_principles/des_princ.xml index 0e087cf843..8ab8661c2d 100644 --- a/system/doc/design_principles/des_princ.xml +++ b/system/doc/design_principles/des_princ.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -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/distributed_applications.xml b/system/doc/design_principles/distributed_applications.xml index f1624a9ad7..a1a0149eb5 100644 --- a/system/doc/design_principles/distributed_applications.xml +++ b/system/doc/design_principles/distributed_applications.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/design_principles/events.xml b/system/doc/design_principles/events.xml index 3c9d0996dc..e37b8b460d 100644 --- a/system/doc/design_principles/events.xml +++ b/system/doc/design_principles/events.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/design_principles/fsm.xml b/system/doc/design_principles/fsm.xml index f58b50cbff..4f2b75e6e8 100644 --- a/system/doc/design_principles/fsm.xml +++ b/system/doc/design_principles/fsm.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -30,6 +30,16 @@ <file>fsm.xml</file> </header> <marker id="gen_fsm behaviour"></marker> + <note> + <p> + There is a new behaviour + <seealso marker="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/gen_server_concepts.xml b/system/doc/design_principles/gen_server_concepts.xml index f8f98918fa..c1b98189d5 100644 --- a/system/doc/design_principles/gen_server_concepts.xml +++ b/system/doc/design_principles/gen_server_concepts.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/design_principles/included_applications.xml b/system/doc/design_principles/included_applications.xml index 3257795e5f..34501c0296 100644 --- a/system/doc/design_principles/included_applications.xml +++ b/system/doc/design_principles/included_applications.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/design_principles/part.xml b/system/doc/design_principles/part.xml index 42fd3beb6a..6495211e04 100644 --- a/system/doc/design_principles/part.xml +++ b/system/doc/design_principles/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -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 20ddc3dbf5..4f71ad4437 100644 --- a/system/doc/design_principles/release_handling.xml +++ b/system/doc/design_principles/release_handling.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2014</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -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/release_structure.xml b/system/doc/design_principles/release_structure.xml index 6e7ab06094..a0ab21c43f 100644 --- a/system/doc/design_principles/release_structure.xml +++ b/system/doc/design_principles/release_structure.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/design_principles/spec_proc.xml b/system/doc/design_principles/spec_proc.xml index 3d7a88da3f..5b156ac263 100644 --- a/system/doc/design_principles/spec_proc.xml +++ b/system/doc/design_principles/spec_proc.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2014</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -522,9 +522,36 @@ init(Parent, Name, Module) -> -module(db). -behaviour(simple_server). --export([init/0, handle_req/2, terminate/0]). +-export([init/1, handle_req/2, terminate/0]). ...</code> + + <p>The contracts specified with <c>-callback</c> attributes in + behaviour modules can be further refined by adding <c>-spec</c> + attributes in callback modules. This can be useful as + <c>-callback</c> contracts are usually generic. The same callback + module with contracts for the callbacks:</p> + + <code type="none"> +-module(db). +-behaviour(simple_server). + +-export([init/1, handle_req/2, terminate/0]). + +-record(state, {field1 :: [atom()], field2 :: integer()}). + +-type state() :: #state{}. +-type request() :: {'store', term(), term()}; + {'lookup', term()}. + +... + +-spec handle_req(request(), state()) -> {'ok', term()}. + +...</code> + + <p>Each <c>-spec</c> contract is to be a subtype of the respective + <c>-callback</c> contract.</p> + </section> </chapter> - diff --git a/system/doc/design_principles/statem.xml b/system/doc/design_principles/statem.xml new file mode 100644 index 0000000000..b63327291d --- /dev/null +++ b/system/doc/design_principles/statem.xml @@ -0,0 +1,1457 @@ +<?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 Behavior</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 <c>STDLIB</c>, where all interface functions and callback + functions are described in detail. + </p> + <note> + <p> + This is a new behavior in Erlang/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. + Depending on user feedback, we do not expect + but can find it necessary to make minor + not backward compatible changes into Erlang/OTP 20.0. + </p> + </note> + +<!-- =================================================================== --> + + <section> + <title>Event-Driven State Machines</title> + <p> + Established Automata theory does not deal much with + how a state transition is triggered, + but 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 following form: + </p> + <pre> +State(S) x Event(E) -> Actions(A), State(S')</pre> + <p>These relations are interpreted as follows: + 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>. Notice that <c>S'</c> can be equal to <c>S</c>. + </p> + <p> + As <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> behaviors, <c>gen_statem</c> keeps + a server <c>Data</c> besides the state. Because of this, and as + there is no restriction on the number of states + (assuming that there is enough virtual machine memory) + or on the number of distinct input events, + a state machine implemented with this behavior + is in fact 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> behavior supports two callback modes: + </p> + <list type="bulleted"> + <item> + <p> + In mode + <seealso marker="stdlib:gen_statem#type-callback_mode"><c>state_functions</c></seealso>, + the state transition rules are written as some Erlang + functions, which conform to the following convention: + </p> + <pre> +StateName(EventType, EventContent, Data) -> + .. code for actions here ... + {next_state, NewStateName, NewData}.</pre> + </item> + <item> + <p> + In mode + <seealso marker="stdlib:gen_statem#type-callback_mode"><c>handle_event_function</c></seealso>, + only one Erlang function provides all state transition rules: + </p> + <pre> +handle_event(EventType, EventContent, State, Data) -> + .. code for actions here ... + {next_state, NewState, NewData}</pre> + </item> + </list> + <p> + Both these modes allow other return tuples; see + <seealso marker="stdlib:gen_statem#Module:StateName/3"><c>Module:StateName/3</c></seealso> + in the <c>gen_statem</c> manual page. + 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> + give different possibilities + and restrictions, but one goal remains: + you want to handle all possible combinations of + events and states. + </p> + <p> + This can be done, for example, by focusing on one state at the time + and for every state ensure that all events are handled. + Alternatively, you can focus on one event at the time + and ensure that it is handled in every state. + You can also use a mix of these strategies. + </p> + <p> + With <c>state_functions</c>, you are restricted to use + atom-only states, and the <c>gen_statem</c> engine + branches depending 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, which 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 all events and states are handled in the same callback function. + </p> + <p> + This mode works equally well when you want to focus on + one event at the time or on + one state at the time, but function + <seealso marker="stdlib:gen_statem#Module:handle_event/4"><c>Module:handle_event/4</c></seealso> + quickly grows too large to handle without branching to + helper functions. + </p> + <p> + The mode enables the use of non-atom states, for example, + complex states or even hierarchical states. + If, for example, a state diagram is largely alike + for the client side and the server side of a protocol, + you can have a state <c>{StateName,server}</c> or + <c>{StateName,client}</c>, + and make <c>StateName</c> determine 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 example starts off as equivalent to the example in section + <seealso marker="fsm"><c>gen_fsm</c> Behavior</seealso>. + In later sections, additions and tweaks are made + using features in <c>gen_statem</c> that <c>gen_fsm</c> does not have. + The end of this chapter provides the example again + with all the added features. + </p> + <p> + A door with a code lock can be seen as a state machine. + Initially, the door is locked. When someone presses a button, + an event is generated. + Depending on what buttons have been pressed before, + the sequence so far can be correct, incomplete, or wrong. + If correct, the door is unlocked for 10 seconds (10,000 milliseconds). + If incomplete, we wait for another button to be pressed. If + 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> + This code lock state machine can be implemented 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, <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 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 specified + as <c>{global,Name}</c>, then the <c>gen_statem</c> is + registered using + <seealso marker="kernel:global#register_name/2"><c>global:register_name/2</c></seealso> + in <c>Kernel</c>. + </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 + code and the server-side code contained in one module. + </p> + </item> + <item> + <p> + The third argument, <c>Code</c>, is a list of digits, which + is the correct unlock code that is passed + to callback function <c>init/1</c>. + </p> + </item> + <item> + <p> + The fourth argument, <c>[]</c>, is a list of options. + For the available options, see + <seealso marker="stdlib:gen_statem#start_link/3"><c>gen_statem:start_link/3</c></seealso>. + </p> + </item> + </list> + <p> + If name registration succeeds, the new <c>gen_statem</c> process + calls 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 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 that 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 key <c>code</c> that stores + the correct button sequence, and 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>Function + <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> + is initialized and is ready to receive events. + </p> + <p> + Function + <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. + Another function, + <seealso marker="stdlib:gen_statem#start/3"><c>gen_statem:start</c></seealso> + can be used 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>Handling Events</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, we use the + same macro <c>?NAME</c> as when starting. + <c>{button,Digit}</c> is the 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. + 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, as + any event cancels the event timer, so no + time-out event occurs 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> + 10,000 is a time-out value in milliseconds. + After this time (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 events 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> + Consider a <c>code_length/0</c> function that returns + the length of the correct code + (that should not be sensitive to reveal). + We 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 mode <c>handle_event_function</c> is used, + all events are handled in + <seealso marker="stdlib:gen_statem#Module:handle_event/4"><c>Module:handle_event/4</c></seealso> + and we can (but do not have to) use an event-centered approach + where we first branch depending on event + and then depending on state: + </p> + <code type="erl"><![CDATA[ +... +-define(CALLBACK_MODE, handle_event_function). + +... +-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 function <c>init/1</c> set itself to trap exit signals + by calling + <seealso marker="erts:erlang#process_flag/2"><c>process_flag(trap_exit, true)</c></seealso>: + </p> + <code type="erl"><![CDATA[ +init(Args) -> + process_flag(trap_exit, true), + do_lock(), + ... + ]]></code> + <p> + When ordered to shut down, the <c>gen_statem</c> then calls + callback function <c>terminate(shutdown, State, Data)</c>. + </p> + <p> + In the following example, function <c>terminate/3</c> + locks 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 callback function + <c>terminate/3</c> just like for a supervised server + and waits for the process to terminate. + </p> + </section> + </section> + +<!-- =================================================================== --> + + <section> + <title>Actions</title> + <p> + In the first sections actions were mentioned as a part of + the general state machine model. These general actions + are implemented with the code that callback module + <c>gen_statem</c> 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 and can do the following: + </p> + <list type="bulleted"> + <item>Postpone the current event</item> + <item>Hibernate the <c>gen_statem</c></item> + <item>Start an event time-out</item> + <item>Reply to a caller</item> + <item>Generate the next event to handle</item> + </list> + <p> + In the example earlier was mentioned the event time-out + and replying to a caller. + An example of event postponing is included later in this chapter. + For details, see the + <seealso marker="stdlib:gen_statem#type-action"><c>gen_statem(3)</c></seealso> + manual page. + You can, for example, reply to many callers + and generate multiple next events to handle. + </p> + </section> + +<!-- =================================================================== --> + + <section> + <title>Event Types</title> + <p> + The previous sections 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> + The following is a 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 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 state transition action + <c>{next_event,internal,EventContent}</c>. + All event types above can also be generated using + <c>{next_event,EventType,EventContent}</c>. + </item> + </taglist> + </section> + +<!-- =================================================================== --> + + <section> + <title>State Time-Outs</title> + <p> + The time-out event generated by state transition action + <c>{timeout,Time,EventContent}</c> is an event time-out, + that is, if an event arrives the timer is cancelled. + You get either an event or a time-out, but not both. + </p> + <p> + Often you want a timer not to be cancelled by any event + or you want to start a timer in one state and respond + to the time-out 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> + For the example so far in this chapter: 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 time-out is cancelled and the button event is delivered. + So, we choose to lock the door if this occurred. + </p> + <p> + Suppose that 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 waits 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 because of some other event, you can use + <seealso marker="erts:erlang#cancel_timer/2"><c>erlang:cancel_timer(Tref)</c></seealso>. + Notice that a time-out message cannot arrive after this, + unless you have postponed it (see the next section) before, + so ensure that you do not accidentally postpone such messages. + </p> + <p> + Another way to cancel a timer is not to cancel it, + but 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, that is, <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 are 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>: + if a change in the item value affects which events that + are handled, then this item is to be part of the state. + </p> + <p> + You want to avoid that you maybe much later decide + to postpone an event in one state and by misfortune it is never retried, + as 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: 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. The following 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 implicitly <c>open</c> + to postpone any events to the <c>locked</c> state. + </p> + <p> + A selective receive cannot be used from a <c>gen_statem</c> + behavior as for any <c>gen_*</c> behavior, + as the receive statement is within the <c>gen_*</c> engine itself. + It must be there because all + <seealso marker="stdlib:sys"><c>sys</c></seealso> + compatible behaviors 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 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> + Both mechanisms have the same theoretical + time and memory complexity, while the selective receive + language construct has smaller constant factors. + </p> + </section> + </section> + +<!-- =================================================================== --> + + <section> + <title>Self-Generated Events</title> + <p> + It can sometimes be beneficial 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 action + <c>next_event</c>. Hence, it cannot 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 can be when you have + a state machine specification that uses state entry actions. + You can code that 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: everywhere you go to + the state, you must explicitly + insert the <c>internal</c> event + or use a state transition function. + </p> + <p> + The following is an implementation of entry actions + using <c>internal</c> events with content <c>enter</c> + using 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> + This section includes the example after all mentioned modifications + and some more using 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> + Notice that this state diagram does not specify how to handle + a button event in the state <c>open</c>. So, you need to + read somewhere else that unspecified events + must be ignored as in not consumed but handled in some other state. + Also, the state diagram does not show that the <c>code_length/0</c> + call must 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> + This section describes what to change in the example + to use one <c>handle_event/4</c> function. + The previously used approach to first branch depending on event + does not work that well here because of the generated + entry actions, so this example first branches depending on state: + </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> + Notice 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 + print the full internal state in the error log, for example, + when killed by an exit signal or because of an internal error. + This state contains both the code lock code + and which digits that remain to unlock. + </p> + <p> + This state data can be regarded as sensitive, + and maybe not what you want in the error log + because of some unpredictable event. + </p> + <p> + Another reason to filter the state can be + that the state is too large to print, as 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 function + <seealso marker="stdlib:gen_statem#Module:format_status/2"><c>Module:format_status/2</c></seealso>, + 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 section + <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 in combination with postponing events. + We complicate the previous example + by introducing a configurable lock button + (this is the state item in question), + which 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 until now was not the lock button. + The sensible thing can be to say that + the button was pressed too early so it is + not to be recognized as the lock button. + However, then it can 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 we make the <c>button/1</c> function synchronous + by using + <seealso marker="stdlib:gen_statem#call/2"><c>gen_statem:call</c></seealso> + 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 does not return until the state transits to <c>locked</c>, + as it is there the event is handled and the reply is sent. + </p> + <p> + If a process now calls <c>set_lock_button/1</c> + to change the lock button while another process + hangs in <c>button/1</c> with the new lock button, + it can 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 that when we change the lock button, the state changes + and all postponed events are 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 can be an ill-fitting model for a physical code lock + that the <c>button/1</c> call can hang until the lock + is locked. But for an API in general it is not that strange. + </p> + </section> + +<!-- =================================================================== --> + + <section> + <title>Hibernation</title> + <p> + If you have many servers in one node + and they have some state(s) in their lifetime in which + the servers can be expected to idle for a while, + and the amount of heap memory all these servers need + is a problem, then the memory footprint of a server + can be mimimized by hibernating it through + <seealso marker="stdlib:proc_lib#hibernate/3"><c>proc_lib:hibernate/3</c></seealso>. + </p> + <note> + <p> + It is rather costly to hibernate a process; see + <seealso marker="erts:erlang#hibernate/3"><c>erlang:hibernate/3</c></seealso>. + It is not something you want to do after every event. + </p> + </note> + <p> + We can in this example hibernate in the <c>{open,_}</c> state, + because what normally occurs in that state is that + the state time-out after a while + triggers a transition to <c>{locked,_}</c>: + </p> + <code type="erl"><![CDATA[ +... +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},[hibernate]}; +... + ]]></code> + <p> + The + <seealso marker="stdlib:gen_statem#type-hibernate"><c>[hibernate]</c></seealso> + action list on the last line + when entering the <c>{open,_}</c> state is the only change. + If any event arrives in the <c>{open,_},</c> state, we + do not bother to rehibernate, so the server stays + awake after any event. + </p> + <p> + To change that we would need to insert + action <c>hibernate</c> in more places. + For example, for the state-independent <c>set_lock_button</c> + and <c>code_length</c> operations that then would have to + be aware of using <c>hibernate</c> while in the + <c>{open,_}</c> state, which would clutter the code. + </p> + <p> + This server probably does not use + heap memory worth hibernating for. + To gain anything from hibernation, your server would + have to produce some garbage during callback execution, + for which this example server can serve as a bad example. + </p> + </section> + +</chapter> diff --git a/system/doc/design_principles/sup_princ.xml b/system/doc/design_principles/sup_princ.xml index 5e2f6ba9cb..a77b3964fc 100644 --- a/system/doc/design_principles/sup_princ.xml +++ b/system/doc/design_principles/sup_princ.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2014</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -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> @@ -229,7 +230,7 @@ child_spec() = #{id => child_id(), % mandatory is <c>rest_for_one</c> or <c>one_for_all</c> and a sibling death causes the temporary process to be terminated).</item> <item>A <c>transient</c> child process is restarted only if it - terminates abnormally, that is, with another exit reason than + terminates abnormally, that is, with an exit reason other than <c>normal</c>, <c>shutdown</c>, or <c>{shutdown,Term}</c>.</item> </list> <p>The <c>restart</c> key is optional. If it is not given, the @@ -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 3032ac3ab9..e476255d62 100644 --- a/system/doc/design_principles/xmlfiles.mk +++ b/system/doc/design_principles/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. @@ -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/efficiency_guide/Makefile b/system/doc/efficiency_guide/Makefile index 0665bb91f7..36e4cd00df 100644 --- a/system/doc/efficiency_guide/Makefile +++ b/system/doc/efficiency_guide/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2001-2012. All Rights Reserved. +# Copyright Ericsson AB 2001-2016. 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. diff --git a/system/doc/efficiency_guide/advanced.xml b/system/doc/efficiency_guide/advanced.xml index d4e47f4f10..016302fe50 100644 --- a/system/doc/efficiency_guide/advanced.xml +++ b/system/doc/efficiency_guide/advanced.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -35,8 +35,7 @@ how much memory different data types and operations require. It is implementation-dependent how much memory the Erlang data types and other items consume, but the following table shows some figures for - the <c>erts-5.2</c> system in R9B. There have been no significant - changes in R13.</p> + the <c>erts-8.0</c> system in OTP 19.0.</p> <p>The unit of measurement is memory words. There exists both a 32-bit and a 64-bit implementation. A word is therefore 4 bytes or @@ -87,6 +86,19 @@ <cell>2 words + the size of each element.</cell> </row> <row> + <cell>Small Map</cell> + <cell>4 words + 2 words per entry (key and value) + the size of each key and value pair.</cell> + </row> + <row> + <cell>Large Map</cell> + <cell> + At least, 2 words + 2 x <c>N</c> words + 2 x log16(<c>N</c>) words + + the size of each key and value pair, where <c>N</c> is the number of pairs in the Map. + A large Map is represented as a tree internally where each node in the tree is a + "sparse tuple" of arity 16. + </cell> + </row> + <row> <cell>Pid</cell> <cell>1 word for a process identifier from the current local node + 5 words for a process identifier from another node.<br></br> @@ -122,7 +134,7 @@ </row> <row> <cell>Erlang process</cell> - <cell>327 words when spawned, including a heap of 233 words.</cell> + <cell>338 words when spawned, including a heap of 233 words.</cell> </row> <tcaption>Memory Size of Different Data Types</tcaption> </table> diff --git a/system/doc/efficiency_guide/appendix.xml b/system/doc/efficiency_guide/appendix.xml index 1e2e906515..225c8c4e2f 100644 --- a/system/doc/efficiency_guide/appendix.xml +++ b/system/doc/efficiency_guide/appendix.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>2002</year> - <year>2013</year> + <year>2016</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/binaryhandling.xml b/system/doc/efficiency_guide/binaryhandling.xml index 0964b759d8..0295d18644 100644 --- a/system/doc/efficiency_guide/binaryhandling.xml +++ b/system/doc/efficiency_guide/binaryhandling.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>2007</year> - <year>2014</year> + <year>2016</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/book.xml b/system/doc/efficiency_guide/book.xml index 76f0ad24d3..e3d6fd5fc2 100644 --- a/system/doc/efficiency_guide/book.xml +++ b/system/doc/efficiency_guide/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/commoncaveats.xml b/system/doc/efficiency_guide/commoncaveats.xml index c1d71e745a..ecfeff0349 100644 --- a/system/doc/efficiency_guide/commoncaveats.xml +++ b/system/doc/efficiency_guide/commoncaveats.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/drivers.xml b/system/doc/efficiency_guide/drivers.xml index 202551ab8e..c99701eeba 100644 --- a/system/doc/efficiency_guide/drivers.xml +++ b/system/doc/efficiency_guide/drivers.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2009</year><year>2013</year> + <year>2009</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/functions.xml b/system/doc/efficiency_guide/functions.xml index 9616df554e..4a8248e65c 100644 --- a/system/doc/efficiency_guide/functions.xml +++ b/system/doc/efficiency_guide/functions.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/introduction.xml b/system/doc/efficiency_guide/introduction.xml index 121ce3af21..ca4a41c798 100644 --- a/system/doc/efficiency_guide/introduction.xml +++ b/system/doc/efficiency_guide/introduction.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/listhandling.xml b/system/doc/efficiency_guide/listhandling.xml index c7b5cf9a9a..2ebc877820 100644 --- a/system/doc/efficiency_guide/listhandling.xml +++ b/system/doc/efficiency_guide/listhandling.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/myths.xml b/system/doc/efficiency_guide/myths.xml index 651d909834..5d3ad78b23 100644 --- a/system/doc/efficiency_guide/myths.xml +++ b/system/doc/efficiency_guide/myths.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>2007</year> - <year>2013</year> + <year>2016</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/part.xml b/system/doc/efficiency_guide/part.xml index 2862058bf2..6e10a0c031 100644 --- a/system/doc/efficiency_guide/part.xml +++ b/system/doc/efficiency_guide/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/processes.xml b/system/doc/efficiency_guide/processes.xml index 2d486ef7ff..f2d9712f51 100644 --- a/system/doc/efficiency_guide/processes.xml +++ b/system/doc/efficiency_guide/processes.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/profiling.xml b/system/doc/efficiency_guide/profiling.xml index 4fbec927f4..1f3d503170 100644 --- a/system/doc/efficiency_guide/profiling.xml +++ b/system/doc/efficiency_guide/profiling.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/tablesDatabases.xml b/system/doc/efficiency_guide/tablesDatabases.xml index 865c46bc33..3f77151e55 100644 --- a/system/doc/efficiency_guide/tablesDatabases.xml +++ b/system/doc/efficiency_guide/tablesDatabases.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/efficiency_guide/xmlfiles.mk b/system/doc/efficiency_guide/xmlfiles.mk index e3373d545a..88df9417f5 100644 --- a/system/doc/efficiency_guide/xmlfiles.mk +++ b/system/doc/efficiency_guide/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/embedded/Makefile b/system/doc/embedded/Makefile index c1134dd62c..40a1b1fb23 100644 --- a/system/doc/embedded/Makefile +++ b/system/doc/embedded/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1997-2012. 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. diff --git a/system/doc/embedded/book.xml b/system/doc/embedded/book.xml index 5a414152d0..7737da7d2e 100644 --- a/system/doc/embedded/book.xml +++ b/system/doc/embedded/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/embedded/embedded_nt.xml b/system/doc/embedded/embedded_nt.xml index b35a5edf36..a1a4b90f3c 100644 --- a/system/doc/embedded/embedded_nt.xml +++ b/system/doc/embedded/embedded_nt.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/embedded/embedded_solaris.xml b/system/doc/embedded/embedded_solaris.xml index ade5ad344e..f8febcc546 100644 --- a/system/doc/embedded/embedded_solaris.xml +++ b/system/doc/embedded/embedded_solaris.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/embedded/intro.xml b/system/doc/embedded/intro.xml index 7fea2eeb82..2b9d35d24c 100644 --- a/system/doc/embedded/intro.xml +++ b/system/doc/embedded/intro.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>1997</year> - <year>2013</year> + <year>2016</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> diff --git a/system/doc/embedded/part.xml b/system/doc/embedded/part.xml index 7bac643be7..d359a888e7 100644 --- a/system/doc/embedded/part.xml +++ b/system/doc/embedded/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/embedded/starting.xml b/system/doc/embedded/starting.xml index f9454f1021..720383e8ac 100644 --- a/system/doc/embedded/starting.xml +++ b/system/doc/embedded/starting.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1996</year><year>2013</year> + <year>1996</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/embedded/target.xml b/system/doc/embedded/target.xml index 20ef6b0fc6..754269aa2f 100644 --- a/system/doc/embedded/target.xml +++ b/system/doc/embedded/target.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1996</year><year>2013</year> + <year>1996</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/embedded/vme_problems.xml b/system/doc/embedded/vme_problems.xml index 54618935cd..ac276ce9d3 100644 --- a/system/doc/embedded/vme_problems.xml +++ b/system/doc/embedded/vme_problems.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>1997</year> - <year>2013</year> + <year>2016</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> diff --git a/system/doc/embedded/xmlfiles.mk b/system/doc/embedded/xmlfiles.mk index 4446aa1516..1e0c71c726 100644 --- a/system/doc/embedded/xmlfiles.mk +++ b/system/doc/embedded/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009-2013. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/embedded/xntp.xml b/system/doc/embedded/xntp.xml index 2f4dc9a534..46213c7865 100644 --- a/system/doc/embedded/xntp.xml +++ b/system/doc/embedded/xntp.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>1997</year> - <year>2013</year> + <year>2016</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> diff --git a/system/doc/getting_started/Makefile b/system/doc/getting_started/Makefile index f16dc0dde1..1fe3d39e4e 100644 --- a/system/doc/getting_started/Makefile +++ b/system/doc/getting_started/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1996-2012. 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. diff --git a/system/doc/getting_started/book.xml b/system/doc/getting_started/book.xml index 8dfca19480..1d92105429 100644 --- a/system/doc/getting_started/book.xml +++ b/system/doc/getting_started/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1996</year><year>2013</year> + <year>1996</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/getting_started/conc_prog.xml b/system/doc/getting_started/conc_prog.xml index 9f13ee4802..f3136898ad 100644 --- a/system/doc/getting_started/conc_prog.xml +++ b/system/doc/getting_started/conc_prog.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/getting_started/intro.xml b/system/doc/getting_started/intro.xml index 6ac4f912fe..afae4e8c18 100644 --- a/system/doc/getting_started/intro.xml +++ b/system/doc/getting_started/intro.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/getting_started/part.xml b/system/doc/getting_started/part.xml index 4b902f4c63..71e551a404 100644 --- a/system/doc/getting_started/part.xml +++ b/system/doc/getting_started/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/getting_started/records_macros.xml b/system/doc/getting_started/records_macros.xml index dd2441b64e..3fcdb10088 100644 --- a/system/doc/getting_started/records_macros.xml +++ b/system/doc/getting_started/records_macros.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/getting_started/robustness.xml b/system/doc/getting_started/robustness.xml index abd5892b80..6932f0ca0f 100644 --- a/system/doc/getting_started/robustness.xml +++ b/system/doc/getting_started/robustness.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/getting_started/seq_prog.xml b/system/doc/getting_started/seq_prog.xml index 5698405ed2..6b7e1cd24f 100644 --- a/system/doc/getting_started/seq_prog.xml +++ b/system/doc/getting_started/seq_prog.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/getting_started/xmlfiles.mk b/system/doc/getting_started/xmlfiles.mk index 892db0e8de..d5a41121d6 100644 --- a/system/doc/getting_started/xmlfiles.mk +++ b/system/doc/getting_started/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/installation_guide/Makefile b/system/doc/installation_guide/Makefile index 52485382d5..673c203422 100644 --- a/system/doc/installation_guide/Makefile +++ b/system/doc/installation_guide/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1996-2014. 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. diff --git a/system/doc/installation_guide/book.xml b/system/doc/installation_guide/book.xml index 92a64345c0..a7686252c6 100644 --- a/system/doc/installation_guide/book.xml +++ b/system/doc/installation_guide/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/installation_guide/install-binary.xml b/system/doc/installation_guide/install-binary.xml index 43f5a57077..b070c02633 100644 --- a/system/doc/installation_guide/install-binary.xml +++ b/system/doc/installation_guide/install-binary.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2000</year><year>2014</year> + <year>2000</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/installation_guide/part.xml b/system/doc/installation_guide/part.xml index 0aacd0f49b..7e51e6ae84 100644 --- a/system/doc/installation_guide/part.xml +++ b/system/doc/installation_guide/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>2000</year><year>2014</year> + <year>2000</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/installation_guide/xmlfiles.mk b/system/doc/installation_guide/xmlfiles.mk index 05effe1534..3f720e1ee5 100644 --- a/system/doc/installation_guide/xmlfiles.mk +++ b/system/doc/installation_guide/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009-2014. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/oam/Makefile b/system/doc/oam/Makefile index 0638a4dbd6..9095744423 100644 --- a/system/doc/oam/Makefile +++ b/system/doc/oam/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1997-2012. 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. diff --git a/system/doc/oam/book.xml b/system/doc/oam/book.xml index 93f5fe344a..05aa2334a5 100644 --- a/system/doc/oam/book.xml +++ b/system/doc/oam/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/oam/oam_intro.xml b/system/doc/oam/oam_intro.xml index 22a2080fd9..cdcb6e3111 100644 --- a/system/doc/oam/oam_intro.xml +++ b/system/doc/oam/oam_intro.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/oam/part.xml b/system/doc/oam/part.xml index efbaa05b94..817b70751c 100644 --- a/system/doc/oam/part.xml +++ b/system/doc/oam/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/oam/xmlfiles.mk b/system/doc/oam/xmlfiles.mk index 5876243466..b2351c661c 100644 --- a/system/doc/oam/xmlfiles.mk +++ b/system/doc/oam/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/programming_examples/Makefile b/system/doc/programming_examples/Makefile index e5f7a330f4..237076d770 100644 --- a/system/doc/programming_examples/Makefile +++ b/system/doc/programming_examples/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2003-2012. All Rights Reserved. +# Copyright Ericsson AB 2003-2016. 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. diff --git a/system/doc/programming_examples/book.xml b/system/doc/programming_examples/book.xml index c6eb4fec97..0f0fca5874 100644 --- a/system/doc/programming_examples/book.xml +++ b/system/doc/programming_examples/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/programming_examples/funs.xmlsrc b/system/doc/programming_examples/funs.xmlsrc index 8469f0871c..bb519be612 100644 --- a/system/doc/programming_examples/funs.xmlsrc +++ b/system/doc/programming_examples/funs.xmlsrc @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -212,7 +212,7 @@ f(...) -> ... end, ...) ...</code> - <p>instead of writng the following code:</p> + <p>instead of writing the following code:</p> <code type="none"> f(...) -> Y = ... diff --git a/system/doc/programming_examples/list_comprehensions.xml b/system/doc/programming_examples/list_comprehensions.xml index 5667571ec5..706cb337ad 100644 --- a/system/doc/programming_examples/list_comprehensions.xml +++ b/system/doc/programming_examples/list_comprehensions.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/programming_examples/part.xml b/system/doc/programming_examples/part.xml index e1f8cc5d57..930646ff4b 100644 --- a/system/doc/programming_examples/part.xml +++ b/system/doc/programming_examples/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/programming_examples/records.xml b/system/doc/programming_examples/records.xml index 6bda6dc0fd..da346dd0b3 100644 --- a/system/doc/programming_examples/records.xml +++ b/system/doc/programming_examples/records.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/programming_examples/xmlfiles.mk b/system/doc/programming_examples/xmlfiles.mk index cc77f48253..5129e488f4 100644 --- a/system/doc/programming_examples/xmlfiles.mk +++ b/system/doc/programming_examples/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/reference_manual/Makefile b/system/doc/reference_manual/Makefile index 30febb1ade..e14a056979 100644 --- a/system/doc/reference_manual/Makefile +++ b/system/doc/reference_manual/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2003-2012. All Rights Reserved. +# Copyright Ericsson AB 2003-2016. 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. diff --git a/system/doc/reference_manual/book.xml b/system/doc/reference_manual/book.xml index 6b7306fb77..590d3580a4 100644 --- a/system/doc/reference_manual/book.xml +++ b/system/doc/reference_manual/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/reference_manual/code_loading.xml b/system/doc/reference_manual/code_loading.xml index e9da40e02f..f6fd2911fa 100644 --- a/system/doc/reference_manual/code_loading.xml +++ b/system/doc/reference_manual/code_loading.xml @@ -130,26 +130,6 @@ loop() -> <marker id="on_load"></marker> <title>Running a Function When a Module is Loaded</title> - <warning> - <p>The <c>on_load</c> feature is to be considered experimental - as there are a number of known weak points in current semantics, - which therefore might change in future Erlang/OTP releases:</p> - <list> - <item><p>Doing external call in <c>on_load</c> to the module itself - leads to deadlock.</p></item> - <item><p>At module upgrade, other processes calling the module - get suspended waiting for <c>on_load</c> to finish. This can be very bad - for applications with demands on realtime characteristics.</p></item> - <item><p>At module upgrade, no rollback is done if the - <c>on_load</c> function fails. - The system is left in a bad limbo state without any working - and reachable instance of the module.</p></item> - </list> - <p>The problems with module upgrade described above can be fixed in future - Erlang/OTP releases by changing the behaviour to not make the module reachable until - after the <c>on_load</c> function has successfully returned.</p> - </warning> - <p>The <c>-on_load()</c> directive names a function that is to be run automatically when a module is loaded.</p> <p>Its syntax is as follows:</p> @@ -159,20 +139,35 @@ loop() -> <p>It is not necessary to export the function. It is called in a freshly spawned process (which terminates as soon as the function - returns). The function must return <c>ok</c> if the module is to - remain loaded and become callable, or any other value if the module - is to be unloaded. Generating an exception also causes the - module to be unloaded. If the return value is not an atom, - a warning error report is sent to the error logger.</p> - - <p>A process that calls any function in a module whose <c>on_load</c> - function has not yet returned, is suspended until the <c>on_load</c> - function has returned.</p> + returns).</p> + + <p>The function must return <c>ok</c> if the module is to + become the new current code for the module and become + callable.</p> + + <p>Returning any other value or generating an exception + causes the new code to be unloaded. If the return value is not an + atom, a warning error report is sent to the error logger.</p> + + <p>If there already is current code for the module, that code will + remain current and can be called until the <c>on_load</c> function + has returned. If the <c>on_load</c> function fails, the current + code (if any) will remain current. If there is no current code for + a module, any process that makes an external call to the module + before the <c>on_load</c> function has finished will be suspended + until the <c>on_load</c> function have finished.</p> + + <note> + <p>Before OTP 19, if the <c>on_load</c> function failed, any + previously current code would become old, essentially leaving + the system without any working and reachable instance of the + module. That problem has been eliminated in OTP 19.</p> + </note> <p>In embedded mode, first all modules are loaded. Then all <c>on_load</c> functions are called. The system is terminated unless all of the <c>on_load</c> functions return - <c>ok</c></p>. + <c>ok</c>.</p> <p><em>Example:</em></p> diff --git a/system/doc/reference_manual/expressions.xml b/system/doc/reference_manual/expressions.xml index 893398b71b..355fd3cfef 100644 --- a/system/doc/reference_manual/expressions.xml +++ b/system/doc/reference_manual/expressions.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> @@ -245,13 +245,13 @@ lists:keysearch(Name, 1, List)</code> handle(Msg, State) spawn(m, init, [])</code> <p><em>Examples</em> where <c>ExprF</c> is a fun:</p> - <code type="none"> -Fun1 = fun(X) -> X+1 end -Fun1(3) -=> 4 - -fun lists:append/2([1,2], [3,4]) -=> [1,2,3,4]</code> + <pre> +1> <input>Fun1 = fun(X) -> X+1 end,</input> +<input>Fun1(3).</input> +4 +2> <input>fun lists:append/2([1,2], [3,4]).</input> +[1,2,3,4] +3> </pre> <p>Notice that when calling a local function, there is a difference between using the implicitly or fully qualified function name. @@ -1004,7 +1004,7 @@ M4 = M3#{a := 2, b := 3}. % 'a' and 'b' was added in `M1` and `M2`.</code> </p> <list> <item><p>A <c>badmatch</c> exception.</p> - <p>This is if it is used in the context of the matching operator + <p>This is if it is used in the context of the match operator as in the example.</p> </item> <item><p>Or resulting in the next clause being tested in function heads and @@ -1085,7 +1085,7 @@ Ei = Value | <p>Used in a bit string construction, <c>Value</c> is an expression that is to evaluate to an integer, float, or bit string. If the expression is not a single literal or variable, it - is to be enclosed in parenthesis.</p> + is to be enclosed in parentheses.</p> <p>Used in a bit string matching, <c>Value</c> must be a variable, or an integer, float, or string.</p> @@ -1319,7 +1319,7 @@ catch Expr</code> {'EXIT',{badarith,[...]}}</pre> <p>Notice that <c>catch</c> has low precedence and catch subexpressions often needs to be enclosed in a block - expression or in parenthesis:</p> + expression or in parentheses:</p> <pre> 3> <input>A = catch 1+2.</input> ** 1: syntax error before: 'catch' ** @@ -1556,9 +1556,11 @@ end</pre> <p>Bit string comprehensions are written with the following syntax:</p> <pre> -<< BitString || Qualifier1,...,QualifierN >></pre> - <p>Here, <c>BitString</c> is a bit string expression and each - <c>Qualifier</c> is either a generator, a bit string generator or a filter.</p> +<< BitStringExpr || Qualifier1,...,QualifierN >></pre> + <p><c>BitStringExpr</c> is an expression that evalutes to a bit + string. If <c>BitStringExpr</c> is a function call, it must be + enclosed in parentheses. Each <c>Qualifier</c> is either a + generator, a bit string generator or a filter.</p> <list type="bulleted"> <item>A <em>generator</em> is written as: <br></br> <c><![CDATA[Pattern <- ListExpr]]></c>. <br></br> diff --git a/system/doc/reference_manual/macros.xml b/system/doc/reference_manual/macros.xml index 3b1f72e5d6..350bb1d123 100644 --- a/system/doc/reference_manual/macros.xml +++ b/system/doc/reference_manual/macros.xml @@ -146,6 +146,10 @@ bar(X) -> <item>The current line number.</item> <tag><c>?MACHINE</c>.</tag> <item>The machine name, <c>'BEAM'</c>.</item> + <tag><c>?FUNCTION_NAME</c></tag> + <item>The name of the current function.</item> + <tag><c>?FUNCTION_ARITY</c></tag> + <item>The arity (number of arguments) for the current function.</item> </taglist> </section> @@ -230,6 +234,53 @@ or </section> <section> + <title>-error() and -warning() directives</title> + + <p>The directive <c>-error(Term)</c> causes a compilation error.</p> + + <p><em>Example:</em></p> + <code type="none"> +-module(t). +-export([version/0]). + +-ifdef(VERSION). +version() -> ?VERSION. +-else. +-error("Macro VERSION must be defined."). +version() -> "". +-endif.</code> + + <p>The error message will look like this:</p> + + <pre> +% <input>erlc t.erl</input> +t.erl:7: -error("Macro VERSION must be defined.").</pre> + + <p>The directive <c>-warning(Term)</c> causes a compilation warning.</p> + + <p><em>Example:</em></p> + <code type="none"> +-module(t). +-export([version/0]). + +-ifndef(VERSION). +-warning("Macro VERSION not defined -- using default version."). +-define(VERSION, "0"). +-endif. +version() -> ?VERSION.</code> + + <p>The warning message will look like this:</p> + + <pre> +% <input>erlc t.erl</input> +t.erl:5: Warning: -warning("Macro VERSION not defined -- using default version.").</pre> + + <p>The <c>-error()</c> and <c>-warning()</c> directives were added + in OTP 19.</p> + + </section> + + <section> <title>Stringifying Macro Arguments</title> <p>The construction <c>??Arg</c>, where <c>Arg</c> is a macro argument, is expanded to a string containing the tokens of @@ -249,5 +300,6 @@ io:format("Call ~s: ~w~n",["you : function ( 2 , 1 )",you:function(2,1)]).</code <p>That is, a trace output, with both the function called and the resulting value.</p> </section> + </chapter> 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> diff --git a/system/doc/reference_manual/part.xml b/system/doc/reference_manual/part.xml index 58483b099a..3d31157973 100644 --- a/system/doc/reference_manual/part.xml +++ b/system/doc/reference_manual/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>2003</year><year>2014</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/reference_manual/patterns.xml b/system/doc/reference_manual/patterns.xml index 043d282de7..57b84b4dfc 100644 --- a/system/doc/reference_manual/patterns.xml +++ b/system/doc/reference_manual/patterns.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/reference_manual/typespec.xml b/system/doc/reference_manual/typespec.xml index 22627058c1..9e26e9058d 100644 --- a/system/doc/reference_manual/typespec.xml +++ b/system/doc/reference_manual/typespec.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> @@ -69,7 +69,7 @@ <p> For integers and atoms, it is allowed for singleton types; for example, the integers - <c>-1</c> and <c>42</c>, or the atoms <c>'foo'</c> and <c>'bar'</c>). + <c>-1</c> and <c>42</c>, or the atoms <c>'foo'</c> and <c>'bar'</c>. All other types are built using unions of either predefined types or singleton types. In a type union between a type and one @@ -132,15 +132,18 @@ | nonempty_list(Type) %% Proper non-empty list Map :: map() %% stands for a map of any size - | #{} %% stands for a map of any size + | #{} %% stands for the empty map | #{PairList} Tuple :: tuple() %% stands for a tuple of any size | {} | {TList} - PairList :: Type => Type - | Type => Type, PairList + PairList :: Pair + | Pair, PairList + + Pair :: Type := Type %% notes a pair that must be present + | Type => Type TList :: Type | Type, TList @@ -148,9 +151,9 @@ Union :: Type1 | Type2 ]]></pre> <p> - The general form of bitstrings is <c><<_:M, _:_*N>></c>, + The general form of bit strings is <c><<_:M, _:_*N>></c>, where <c>M</c> and <c>N</c> are positive integers. It denotes a - bitstring that is <c>M + (k*N)</c> bits long (that is, a bitstring that + bit string that is <c>M + (k*N)</c> bits long (that is, a bit string that starts with <c>M</c> bits and continues with <c>k</c> segments of <c>N</c> bits each, where <c>k</c> is also a positive integer). The notations <c><<_:_*N>></c>, <c><<_:M>></c>, @@ -170,6 +173,23 @@ The notation <c>[]</c> specifies the singleton type for the empty list. </p> <p> + The general form of maps is <c>#{PairList}</c>. The key types in + <c>PairList</c> are allowed to overlap, and if they do, the leftmost pair + takes precedence. A map value does not belong to this type if contains a key + that is not in <c>PairList</c>. + </p> + <p> + Because it is common to end a map type with <c>any() => any()</c> to denote + that keys that do not belong to any other pair in <c>PairList</c> are + allowed, and may map to any value, the shorthand notation <c>...</c> is + allowed as the last pair of a map type. + </p> + <p> + Notice that the syntactic representation of <c>map()</c> is <c>#{...}</c> + (or <c>#{_ => _}</c>, or <c>#{any() => any()}</c>), not <c>#{}</c>. + The notation <c>#{}</c> specifies the singleton type for the empty map. + </p> + <p> For convenience, the following types are also built-in. They can be thought as predefined aliases for the type unions also shown in the table. @@ -302,12 +322,6 @@ This is described in <seealso marker="#typeinrecords"> Type Information in Record Declarations</seealso>. </p> - <note> - <p>Map types, both <c>map()</c> and <c>#{...}</c>, - are considered experimental during OTP 17.</p> - <p>No type information of maps pairs, only the containing map types, - are used by Dialyzer in OTP 17.</p> - </note> </section> <section> @@ -495,7 +509,8 @@ </p> <pre> -spec id(X) -> X when X :: tuple().</pre> <p> - Currently, the <c>::</c> constraint (read as <c>is_subtype</c>) is + Currently, the <c>::</c> constraint + (read as «is a subtype of») is the only guard constraint that can be used in the <c>'when'</c> part of a <c>'-spec'</c> attribute. </p> @@ -513,7 +528,7 @@ <em>the same</em> tuple. </p> <p> - However, it is up to the tools that process the specificationss + However, it is up to the tools that process the specifications to choose whether to take this extra information into account or not. </p> @@ -529,16 +544,6 @@ <pre> -spec foo({X, integer()}) -> X when X :: atom() ; ([Y]) -> Y when Y :: number().</pre> - <note> - <p> - For backwards compatibility the following form is also allowed: - </p> - <pre> -spec id(X) -> X when is_subtype(X, tuple()).</pre> - <p> - but its use is discouraged. It will be removed in a future - Erlang/OTP release. - </p> - </note> <p> Some functions in Erlang are not meant to return; either because they define servers or because they are used to diff --git a/system/doc/reference_manual/xmlfiles.mk b/system/doc/reference_manual/xmlfiles.mk index 323b94c0de..61637ae701 100644 --- a/system/doc/reference_manual/xmlfiles.mk +++ b/system/doc/reference_manual/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/system_architecture_intro/Makefile b/system/doc/system_architecture_intro/Makefile index 8bc86ab312..446e66205c 100644 --- a/system/doc/system_architecture_intro/Makefile +++ b/system/doc/system_architecture_intro/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1997-2012. 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. diff --git a/system/doc/system_architecture_intro/book.xml b/system/doc/system_architecture_intro/book.xml index 318f940a18..4b9f03c7f9 100644 --- a/system/doc/system_architecture_intro/book.xml +++ b/system/doc/system_architecture_intro/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_architecture_intro/part.xml b/system/doc/system_architecture_intro/part.xml index eb0f9e0ba6..c000892449 100644 --- a/system/doc/system_architecture_intro/part.xml +++ b/system/doc/system_architecture_intro/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_architecture_intro/sys_arch_intro.xml b/system/doc/system_architecture_intro/sys_arch_intro.xml index b9535f66f8..cf75e1f100 100644 --- a/system/doc/system_architecture_intro/sys_arch_intro.xml +++ b/system/doc/system_architecture_intro/sys_arch_intro.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2000</year><year>2013</year> + <year>2000</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_architecture_intro/xmlfiles.mk b/system/doc/system_architecture_intro/xmlfiles.mk index 6e7e712703..60c2047796 100644 --- a/system/doc/system_architecture_intro/xmlfiles.mk +++ b/system/doc/system_architecture_intro/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/system_principles/Makefile b/system/doc/system_principles/Makefile index 2bb84474df..77edea8f58 100644 --- a/system/doc/system_principles/Makefile +++ b/system/doc/system_principles/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1996-2012. 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. diff --git a/system/doc/system_principles/book.xml b/system/doc/system_principles/book.xml index 11eacba578..cd84d4cf6b 100644 --- a/system/doc/system_principles/book.xml +++ b/system/doc/system_principles/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1996</year><year>2013</year> + <year>1996</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_principles/create_target.xmlsrc b/system/doc/system_principles/create_target.xmlsrc index ccc26081c3..8a463076f5 100644 --- a/system/doc/system_principles/create_target.xmlsrc +++ b/system/doc/system_principles/create_target.xmlsrc @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2002</year><year>2014</year> + <year>2002</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_principles/error_logging.xml b/system/doc/system_principles/error_logging.xml index 024137a430..c99d59ddb7 100644 --- a/system/doc/system_principles/error_logging.xml +++ b/system/doc/system_principles/error_logging.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_principles/part.xml b/system/doc/system_principles/part.xml index 1557b5ff62..1b87ecd350 100644 --- a/system/doc/system_principles/part.xml +++ b/system/doc/system_principles/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>1997</year><year>2014</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_principles/upgrade.xml b/system/doc/system_principles/upgrade.xml index 173e46185c..c491bd855e 100644 --- a/system/doc/system_principles/upgrade.xml +++ b/system/doc/system_principles/upgrade.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2014</year> + <year>2014</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_principles/versions.xml b/system/doc/system_principles/versions.xml index ee104a8302..3772d773fc 100644 --- a/system/doc/system_principles/versions.xml +++ b/system/doc/system_principles/versions.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2014</year> + <year>2014</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/system_principles/xmlfiles.mk b/system/doc/system_principles/xmlfiles.mk index fcc1fc886f..c3c3bb4731 100644 --- a/system/doc/system_principles/xmlfiles.mk +++ b/system/doc/system_principles/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009-2014. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/top/Makefile b/system/doc/top/Makefile index 7e3041ce1e..caae19a8d1 100644 --- a/system/doc/top/Makefile +++ b/system/doc/top/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1999-2013. All Rights Reserved. +# Copyright Ericsson AB 1999-2016. 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. diff --git a/system/doc/top/book.xml b/system/doc/top/book.xml index 7bbeb38472..c94b0f24d6 100644 --- a/system/doc/top/book.xml +++ b/system/doc/top/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1997</year><year>2013</year> + <year>1997</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/top/src/erl_html_tools.erl b/system/doc/top/src/erl_html_tools.erl index dddf025020..ab58fdf666 100644 --- a/system/doc/top/src/erl_html_tools.erl +++ b/system/doc/top/src/erl_html_tools.erl @@ -2,7 +2,7 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 2009-2011. All Rights Reserved. +%% Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/top/src/erlresolvelinks.erl b/system/doc/top/src/erlresolvelinks.erl index 7946fd4bea..cfe8d0fa0b 100644 --- a/system/doc/top/src/erlresolvelinks.erl +++ b/system/doc/top/src/erlresolvelinks.erl @@ -2,7 +2,7 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 2009-2010. All Rights Reserved. +%% Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/top/src/otp_man_index.erl b/system/doc/top/src/otp_man_index.erl index 753e952ecb..12aaba1423 100644 --- a/system/doc/top/src/otp_man_index.erl +++ b/system/doc/top/src/otp_man_index.erl @@ -2,7 +2,7 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 2010. All Rights Reserved. +%% Copyright Ericsson AB 2010-2016. 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. diff --git a/system/doc/top/templates/applications.html.src b/system/doc/top/templates/applications.html.src index 4be969f9d1..1f73c44d69 100644 --- a/system/doc/top/templates/applications.html.src +++ b/system/doc/top/templates/applications.html.src @@ -2,7 +2,7 @@ <!-- %CopyrightBegin% -Copyright Ericsson AB 2009-2010. All Rights Reserved. +Copyright Ericsson AB 2009-2016. 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. diff --git a/system/doc/top/templates/index.html.src b/system/doc/top/templates/index.html.src index bdac3895b0..9637685946 100644 --- a/system/doc/top/templates/index.html.src +++ b/system/doc/top/templates/index.html.src @@ -2,7 +2,7 @@ <!-- %CopyrightBegin% -Copyright Ericsson AB 2009-2014. All Rights Reserved. +Copyright Ericsson AB 2009-2016. 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. @@ -145,10 +145,10 @@ verification, comment support including paragraph filling, skeletons, tags support and more. See the <a href="#tools#/index.html"> Tools</a> application for details. <p> -There is also an -<a href="http://erlide.org/index.html"> -Erlang plugin (ErlIDE) for Eclipse</a> if you prefer a more graphical -environment. ErlIDE is under active development with new features in almost every release. +There are also Erlang plugins for +<a href="http://erlide.org/index.html">Eclipse (ErlIDE)</a> and +<a href="http://ignatov.github.io/intellij-erlang/">IntelliJ IDEA</a> +if you prefer a more graphical environment, which are both under active development. <li>When developing with Erlang/OTP you usually test your programs from the interactive shell (see <a href="getting_started/users_guide.html"> Getting Started With Erlang</a>) where you can call individual diff --git a/system/doc/tutorial/Makefile b/system/doc/tutorial/Makefile index 868e79cd83..5deea41f0a 100644 --- a/system/doc/tutorial/Makefile +++ b/system/doc/tutorial/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2000-2012. All Rights Reserved. +# Copyright Ericsson AB 2000-2016. 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. diff --git a/system/doc/tutorial/appendix.xmlsrc b/system/doc/tutorial/appendix.xmlsrc index 52c24c1b67..4be6c91fe9 100644 --- a/system/doc/tutorial/appendix.xmlsrc +++ b/system/doc/tutorial/appendix.xmlsrc @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2000</year><year>2013</year> + <year>2000</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/tutorial/book.xml b/system/doc/tutorial/book.xml index 81530f25eb..1841a2df60 100644 --- a/system/doc/tutorial/book.xml +++ b/system/doc/tutorial/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>2000</year><year>2013</year> + <year>2000</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/tutorial/distribution.xml b/system/doc/tutorial/distribution.xml index 40d60acb3a..b489410841 100644 --- a/system/doc/tutorial/distribution.xml +++ b/system/doc/tutorial/distribution.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2000</year><year>2013</year> + <year>2000</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/tutorial/part.xml b/system/doc/tutorial/part.xml index 5216d1653d..4a66f0cb22 100644 --- a/system/doc/tutorial/part.xml +++ b/system/doc/tutorial/part.xml @@ -4,7 +4,7 @@ <part xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>2000</year><year>2013</year> + <year>2000</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> diff --git a/system/doc/tutorial/xmlfiles.mk b/system/doc/tutorial/xmlfiles.mk index 28b66f232d..f8ed7be064 100644 --- a/system/doc/tutorial/xmlfiles.mk +++ b/system/doc/tutorial/xmlfiles.mk @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2009-2010. All Rights Reserved. +# Copyright Ericsson AB 2009-2016. 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. |
