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-rw-r--r--lib/debugger/src/dbg_iserver.erl40
-rw-r--r--lib/debugger/src/dbg_wx_trace.erl13
-rw-r--r--lib/debugger/src/dbg_wx_view.erl12
-rw-r--r--lib/reltool/src/reltool.hrl26
-rw-r--r--lib/ssh/src/ssh_connection_handler.erl12
-rw-r--r--lib/ssl/src/dtls_connection.erl13
-rw-r--r--lib/ssl/src/tls_connection.erl15
-rw-r--r--lib/stdlib/doc/src/gen_statem.xml247
-rw-r--r--lib/stdlib/src/gen_statem.erl260
-rw-r--r--lib/stdlib/test/gen_statem_SUITE.erl121
-rw-r--r--lib/tools/doc/src/erlang_mode.xml9
-rw-r--r--lib/tools/emacs/erlang-skels.el149
-rw-r--r--system/doc/design_principles/statem.xml84
13 files changed, 607 insertions, 394 deletions
diff --git a/lib/debugger/src/dbg_iserver.erl b/lib/debugger/src/dbg_iserver.erl
index 3561454685..3e959e8e30 100644
--- a/lib/debugger/src/dbg_iserver.erl
+++ b/lib/debugger/src/dbg_iserver.erl
@@ -214,7 +214,6 @@ handle_call({new_process, Pid, Meta, Function}, _From, State) ->
%% Code loading
handle_call({load, Mod, Src, Bin}, _From, State) ->
-
%% Create an ETS table for storing information about the module
Db = State#state.db,
ModDb = ets:new(Mod, [ordered_set, public]),
@@ -285,23 +284,28 @@ handle_call({contents, Mod, Pid}, _From, State) ->
{reply, {ok, Bin}, State};
handle_call({raw_contents, Mod, Pid}, _From, State) ->
Db = State#state.db,
- [{{Mod, refs}, ModDbs}] = ets:lookup(Db, {Mod, refs}),
- ModDb = if
- Pid =:= any -> hd(ModDbs);
- true ->
- lists:foldl(fun(T, not_found) ->
- [{T, Pids}] = ets:lookup(Db, T),
- case lists:member(Pid, Pids) of
- true -> T;
- false -> not_found
- end;
- (_T, T) -> T
- end,
- not_found,
- ModDbs)
- end,
- [{mod_raw, Bin}] = ets:lookup(ModDb, mod_raw),
- {reply, {ok, Bin}, State};
+ case ets:lookup(Db, {Mod, refs}) of
+ [{{Mod, refs}, ModDbs}] ->
+ ModDb =
+ if
+ Pid =:= any -> hd(ModDbs);
+ true ->
+ lists:foldl(fun(T, not_found) ->
+ [{T, Pids}] = ets:lookup(Db, T),
+ case lists:member(Pid, Pids) of
+ true -> T;
+ false -> not_found
+ end;
+ (_T, T) -> T
+ end,
+ not_found,
+ ModDbs)
+ end,
+ [{mod_raw, Bin}] = ets:lookup(ModDb, mod_raw),
+ {reply, {ok, Bin}, State};
+ [] -> % code not interpreted
+ {reply, not_found, State}
+ end;
handle_call({is_interpreted, Mod, Name, Arity}, _From, State) ->
Db = State#state.db,
Reply = case ets:lookup(Db, {Mod, refs}) of
diff --git a/lib/debugger/src/dbg_wx_trace.erl b/lib/debugger/src/dbg_wx_trace.erl
index 6af19af33b..29c8e8cefb 100644
--- a/lib/debugger/src/dbg_wx_trace.erl
+++ b/lib/debugger/src/dbg_wx_trace.erl
@@ -818,11 +818,14 @@ gui_show_module(Win, Mod, Line, _Cm, Pid, How) ->
gui_load_module(Win, Mod, _Pid) ->
dbg_wx_trace_win:display(Win,{text, "Loading module..."}),
- %% Contents = int:contents(Mod, Pid),
- {ok, Contents} = dbg_iserver:call({raw_contents, Mod, any}),
- Win2 = dbg_wx_trace_win:show_code(Win, Mod, Contents),
- dbg_wx_trace_win:display(Win,{text, ""}),
- Win2.
+ case dbg_iserver:call({raw_contents, Mod, any}) of
+ {ok, Contents} ->
+ Win2 = dbg_wx_trace_win:show_code(Win, Mod, Contents),
+ dbg_wx_trace_win:display(Win,{text, ""}),
+ Win2;
+ not_found ->
+ dbg_wx_trace_win:show_no_code(Win)
+ end.
gui_update_bindings(Win,Meta) ->
Bs = int:meta(Meta, bindings, nostack),
diff --git a/lib/debugger/src/dbg_wx_view.erl b/lib/debugger/src/dbg_wx_view.erl
index 91fc0d08cb..86d009238f 100644
--- a/lib/debugger/src/dbg_wx_view.erl
+++ b/lib/debugger/src/dbg_wx_view.erl
@@ -263,7 +263,11 @@ shortcut(_) -> false.
gui_load_module(Win, Mod) ->
dbg_wx_trace_win:display(Win,{text, "Loading module..."}),
- {ok, Contents} = dbg_iserver:call({raw_contents, Mod, any}),
- Win2 = dbg_wx_trace_win:show_code(Win, Mod, Contents),
- dbg_wx_trace_win:display(Win,{text, ""}),
- Win2.
+ case dbg_iserver:call({raw_contents, Mod, any}) of
+ {ok, Contents} ->
+ Win2 = dbg_wx_trace_win:show_code(Win, Mod, Contents),
+ dbg_wx_trace_win:display(Win,{text, ""}),
+ Win2;
+ not_found ->
+ dbg_wx_trace_win:show_no_code(Win)
+ end.
diff --git a/lib/reltool/src/reltool.hrl b/lib/reltool/src/reltool.hrl
index 9ac22b9450..89b5f3a997 100644
--- a/lib/reltool/src/reltool.hrl
+++ b/lib/reltool/src/reltool.hrl
@@ -154,19 +154,19 @@
-record(app_info,
{
- description = "" :: string(),
- id = "" :: string(),
- vsn = "" :: app_vsn(),
- modules = [] :: [mod_name()],
- maxP = infinity :: integer() | infinity,
- maxT = infinity :: integer() | infinity,
- registered = [] :: [atom()],
- incl_apps = [] :: [app_name()],
- applications = [] :: [app_name()],
- env = [] :: [{atom(), term()}],
- mod = undefined :: {mod_name(), [term()]} | undefined,
- start_phases = undefined :: [{atom(), term()}] | undefined,
- runtime_dependencies = [] :: [string()]
+ description = "" :: '_' | string(),
+ id = "" :: '_' | string(),
+ vsn = "" :: '_' | app_vsn(),
+ modules = [] :: '_' | [mod_name()],
+ maxP = infinity :: '_' | integer() | infinity,
+ maxT = infinity :: '_' | integer() | infinity,
+ registered = [] :: '_' | [atom()],
+ incl_apps = [] :: '_' | '$3' | [app_name()],
+ applications = [] :: '_' | '$2' | [app_name()],
+ env = [] :: '_' | [{atom(), term()}],
+ mod = undefined :: '_' | {mod_name(), [term()]} | undefined,
+ start_phases = undefined :: '_' | [{atom(), term()}] | undefined,
+ runtime_dependencies = [] :: '_' | [string()]
}).
-record(regexp, {source, compiled}).
diff --git a/lib/ssh/src/ssh_connection_handler.erl b/lib/ssh/src/ssh_connection_handler.erl
index f9f4c82351..dcb6ff9343 100644
--- a/lib/ssh/src/ssh_connection_handler.erl
+++ b/lib/ssh/src/ssh_connection_handler.erl
@@ -60,7 +60,8 @@
]).
%%% Behaviour callbacks
--export([handle_event/4, terminate/3, format_status/2, code_change/4]).
+-export([callback_mode/0, handle_event/4, terminate/3,
+ format_status/2, code_change/4]).
%%% Exports not intended to be used :). They are used for spawning and tests
-export([init_connection_handler/3, % proc_lib:spawn needs this
@@ -374,14 +375,12 @@ init_connection_handler(Role, Socket, Opts) ->
S ->
gen_statem:enter_loop(?MODULE,
[], %%[{debug,[trace,log,statistics,debug]} || Role==server],
- handle_event_function,
{hello,Role},
S)
catch
_:Error ->
gen_statem:enter_loop(?MODULE,
[],
- handle_event_function,
{init_error,Error},
S0)
end.
@@ -504,6 +503,9 @@ init_ssh_record(Role, Socket, Opts) ->
%%% ######## Error in the initialisation ####
+callback_mode() ->
+ handle_event_function.
+
handle_event(_, _Event, {init_error,Error}, _) ->
case Error of
{badmatch,{error,enotconn}} ->
@@ -1401,12 +1403,12 @@ fmt_stat_rec(FieldNames, Rec, Exclude) ->
state_name(),
#data{},
term()
- ) -> {gen_statem:callback_mode(), state_name(), #data{}}.
+ ) -> {ok, state_name(), #data{}}.
%% . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
code_change(_OldVsn, StateName, State, _Extra) ->
- {handle_event_function, StateName, State}.
+ {ok, StateName, State}.
%%====================================================================
diff --git a/lib/ssl/src/dtls_connection.erl b/lib/ssl/src/dtls_connection.erl
index b8be686b99..a0d9982aaa 100644
--- a/lib/ssl/src/dtls_connection.erl
+++ b/lib/ssl/src/dtls_connection.erl
@@ -65,9 +65,7 @@
hello/3, certify/3, cipher/3, abbreviated/3, %% Handshake states
connection/3]).
%% gen_statem callbacks
--export([terminate/3, code_change/4, format_status/2]).
-
--define(GEN_STATEM_CB_MODE, state_functions).
+-export([callback_mode/0, terminate/3, code_change/4, format_status/2]).
%%====================================================================
%% Internal application API
@@ -161,12 +159,15 @@ init([Role, Host, Port, Socket, Options, User, CbInfo]) ->
State0 = initial_state(Role, Host, Port, Socket, Options, User, CbInfo),
try
State = ssl_connection:ssl_config(State0#state.ssl_options, Role, State0),
- gen_statem:enter_loop(?MODULE, [], ?GEN_STATEM_CB_MODE, init, State)
+ gen_statem:enter_loop(?MODULE, [], init, State)
catch
throw:Error ->
- gen_statem:enter_loop(?MODULE, [], ?GEN_STATEM_CB_MODE, error, {Error,State0})
+ gen_statem:enter_loop(?MODULE, [], error, {Error,State0})
end.
+callback_mode() ->
+ state_functions.
+
%%--------------------------------------------------------------------
%% State functionsconnection/2
%%--------------------------------------------------------------------
@@ -376,7 +377,7 @@ terminate(Reason, StateName, State) ->
%% Description: Convert process state when code is changed
%%--------------------------------------------------------------------
code_change(_OldVsn, StateName, State, _Extra) ->
- {?GEN_STATEM_CB_MODE, StateName, State}.
+ {ok, StateName, State}.
format_status(Type, Data) ->
ssl_connection:format_status(Type, Data).
diff --git a/lib/ssl/src/tls_connection.erl b/lib/ssl/src/tls_connection.erl
index 9880befa94..eaf866c339 100644
--- a/lib/ssl/src/tls_connection.erl
+++ b/lib/ssl/src/tls_connection.erl
@@ -68,10 +68,8 @@
hello/3, certify/3, cipher/3, abbreviated/3, %% Handshake states
connection/3]).
%% gen_statem callbacks
--export([terminate/3, code_change/4, format_status/2]).
+-export([callback_mode/0, terminate/3, code_change/4, format_status/2]).
--define(GEN_STATEM_CB_MODE, state_functions).
-
%%====================================================================
%% Internal application API
%%====================================================================
@@ -169,11 +167,14 @@ init([Role, Host, Port, Socket, Options, User, CbInfo]) ->
State0 = initial_state(Role, Host, Port, Socket, Options, User, CbInfo),
try
State = ssl_connection:ssl_config(State0#state.ssl_options, Role, State0),
- gen_statem:enter_loop(?MODULE, [], ?GEN_STATEM_CB_MODE, init, State)
+ gen_statem:enter_loop(?MODULE, [], init, State)
catch throw:Error ->
- gen_statem:enter_loop(?MODULE, [], ?GEN_STATEM_CB_MODE, error, {Error, State0})
+ gen_statem:enter_loop(?MODULE, [], error, {Error, State0})
end.
+callback_mode() ->
+ state_functions.
+
%%--------------------------------------------------------------------
%% State functions
%%--------------------------------------------------------------------
@@ -457,9 +458,9 @@ format_status(Type, Data) ->
%%--------------------------------------------------------------------
code_change(_OldVsn, StateName, State0, {Direction, From, To}) ->
State = convert_state(State0, Direction, From, To),
- {?GEN_STATEM_CB_MODE, StateName, State};
+ {ok, StateName, State};
code_change(_OldVsn, StateName, State, _) ->
- {?GEN_STATEM_CB_MODE, StateName, State}.
+ {ok, StateName, State}.
%%--------------------------------------------------------------------
%%% Internal functions
diff --git a/lib/stdlib/doc/src/gen_statem.xml b/lib/stdlib/doc/src/gen_statem.xml
index ed44eef912..3322571b2c 100644
--- a/lib/stdlib/doc/src/gen_statem.xml
+++ b/lib/stdlib/doc/src/gen_statem.xml
@@ -97,6 +97,9 @@ gen_statem module Callback module
gen_statem:start
gen_statem:start_link -----> Module:init/1
+Server start or code change
+ -----> Module:callback_mode/0
+
gen_statem:stop -----> Module:terminate/3
gen_statem:call
@@ -116,9 +119,11 @@ erlang:'!' -----> Module:StateName/3
</p>
<p>
If a callback function fails or returns a bad value,
- the <c>gen_statem</c> terminates. However, an exception of class
+ the <c>gen_statem</c> terminates, unless otherwise stated.
+ However, an exception of class
<seealso marker="erts:erlang#throw/1"><c>throw</c></seealso>
- is not regarded as an error but as a valid return.
+ is not regarded as an error but as a valid return
+ from all callback functions.
</p>
<marker id="state_function"/>
<p>
@@ -127,7 +132,8 @@ erlang:'!' -----> Module:StateName/3
in a <c>gen_statem</c> is the callback function that is called
for all events in this state. It is selected depending on which
<seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
- that the implementation specifies when the server starts.
+ that the callback module defines with the callback function
+ <seealso marker="#Module:callback_mode/0"><c>Module:callback_mode/0</c></seealso>.
</p>
<p>
When the
@@ -138,9 +144,9 @@ erlang:'!' -----> Module:StateName/3
This gathers all code for a specific state
in one function as the <c>gen_statem</c> engine
branches depending on state name.
- Notice that in this mode the mandatory callback function
+ Notice the fact that there is a mandatory callback function
<seealso marker="#Module:terminate/3"><c>Module:terminate/3</c></seealso>
- makes the state name <c>terminate</c> unusable.
+ makes the state name <c>terminate</c> unusable in this mode.
</p>
<p>
When the
@@ -249,11 +255,10 @@ erlang:'!' -----> Module:StateName/3
-behaviour(gen_statem).
-export([start/0,push/0,get_count/0,stop/0]).
--export([terminate/3,code_change/4,init/1]).
+-export([terminate/3,code_change/4,init/1,callback_mode/0]).
-export([on/3,off/3]).
name() -> pushbutton_statem. % The registered server name
-callback_mode() -> state_functions.
%% API. This example uses a registered name name()
%% and does not link to the caller.
@@ -270,15 +275,14 @@ stop() ->
terminate(_Reason, _State, _Data) ->
void.
code_change(_Vsn, State, Data, _Extra) ->
- {callback_mode(),State,Data}.
+ {ok,State,Data}.
init([]) ->
- %% Set the callback mode and initial state + data.
- %% Data is used only as a counter.
+ %% Set the initial state + data. Data is used only as a counter.
State = off, Data = 0,
- {callback_mode(),State,Data}.
-
+ {ok,State,Data}.
+callback_mode() -> state_functions.
-%%% State functions
+%%% State function(s)
off({call,From}, push, Data) ->
%% Go to 'on', increment count and reply
@@ -326,18 +330,13 @@ ok
To compare styles, here follows the same example using
<seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
<c>state_functions</c>, or rather the code to replace
- from function <c>init/1</c> of the <c>pushbutton.erl</c>
+ after function <c>init/1</c> of the <c>pushbutton.erl</c>
example file above:
</p>
<code type="erl">
-init([]) ->
- %% Set the callback mode and initial state + data.
- %% Data is used only as a counter.
- State = off, Data = 0,
- {handle_event_function,State,Data}.
-
+callback_mode() -> handle_event_function.
-%%% Event handling
+%%% State function(s)
handle_event({call,From}, push, off, Data) ->
%% Go to 'on', increment count and reply
@@ -426,8 +425,8 @@ handle_event(_, _, State, Data) ->
<desc>
<p>
Debug option that can be used when starting
- a <c>gen_statem</c> server through, for example,
- <seealso marker="#enter_loop/5"><c>enter_loop/5</c></seealso>.
+ a <c>gen_statem</c> server through,
+ <seealso marker="#enter_loop/4"><c>enter_loop/4-6</c></seealso>.
</p>
<p>
For every entry in <c><anno>Dbgs</anno></c>,
@@ -525,12 +524,9 @@ handle_event(_, _, State, Data) ->
<desc>
<p>
The <em>callback mode</em> is selected when starting the
- <c>gen_statem</c> using the return value from
- <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
- or when calling
- <seealso marker="#enter_loop/5"><c>enter_loop/5,6,7</c></seealso>,
- and with the return value from
- <seealso marker="#Module:code_change/4"><c>Module:code_change/4</c></seealso>.
+ <c>gen_statem</c> and after code change
+ using the return value from
+ <seealso marker="#Module:callback_mode/0"><c>Module:callback_mode/0</c></seealso>.
</p>
<taglist>
<tag><c>state_functions</c></tag>
@@ -691,7 +687,7 @@ handle_event(_, _, State, Data) ->
<seealso marker="#state_function">state function</seealso>, from
<seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
or by giving them to
- <seealso marker="#enter_loop/6"><c>enter_loop/6,7</c></seealso>.
+ <seealso marker="#enter_loop/5"><c>enter_loop/5,6</c></seealso>.
</p>
<p>
Actions are executed in the containing list order.
@@ -923,7 +919,8 @@ handle_event(_, _, State, Data) ->
</p>
<note>
<p>
- To avoid getting a late reply in the caller's
+ For <c><anno>Timeout</anno> =/= infinity</c>,
+ to avoid getting a late reply in the caller's
inbox, this function spawns a proxy process that
does the call. A late reply gets delivered to the
dead proxy process, hence gets discarded. This is
@@ -958,35 +955,36 @@ handle_event(_, _, State, Data) ->
</func>
<func>
- <name name="enter_loop" arity="5"/>
+ <name name="enter_loop" arity="4"/>
<fsummary>Enter the <c>gen_statem</c> receive loop.</fsummary>
<desc>
<p>
The same as
- <seealso marker="#enter_loop/7"><c>enter_loop/7</c></seealso>
- except that no
+ <seealso marker="#enter_loop/6"><c>enter_loop/6</c></seealso>
+ with <c>Actions = []</c> except that no
<seealso marker="#type-server_name"><c>server_name()</c></seealso>
- must have been registered.
+ must have been registered. This creates an anonymous server.
</p>
</desc>
</func>
<func>
- <name name="enter_loop" arity="6"/>
+ <name name="enter_loop" arity="5"/>
<fsummary>Enter the <c>gen_statem</c> receive loop.</fsummary>
<desc>
<p>
If <c><anno>Server_or_Actions</anno></c> is a <c>list()</c>,
the same as
- <seealso marker="#enter_loop/7"><c>enter_loop/7</c></seealso>
+ <seealso marker="#enter_loop/6"><c>enter_loop/6</c></seealso>
except that no
<seealso marker="#type-server_name"><c>server_name()</c></seealso>
must have been registered and
<c>Actions = <anno>Server_or_Actions</anno></c>.
+ This creates an anonymous server.
</p>
<p>
Otherwise the same as
- <seealso marker="#enter_loop/7"><c>enter_loop/7</c></seealso>
+ <seealso marker="#enter_loop/6"><c>enter_loop/6</c></seealso>
with
<c>Server = <anno>Server_or_Actions</anno></c> and
<c>Actions = []</c>.
@@ -995,7 +993,7 @@ handle_event(_, _, State, Data) ->
</func>
<func>
- <name name="enter_loop" arity="7"/>
+ <name name="enter_loop" arity="6"/>
<fsummary>Enter the <c>gen_statem</c> receive loop.</fsummary>
<desc>
<p>
@@ -1015,21 +1013,31 @@ handle_event(_, _, State, Data) ->
the <c>gen_statem</c> behavior provides.
</p>
<p>
- <c><anno>Module</anno></c>, <c><anno>Opts</anno></c>, and
- <c><anno>Server</anno></c> have the same meanings
- as when calling
+ <c><anno>Module</anno></c>, <c><anno>Opts</anno></c>
+ have the same meaning as when calling
<seealso marker="#start_link/3"><c>start[_link]/3,4</c></seealso>.
+ </p>
+ <p>
+ If <c><anno>Server</anno></c> is <c>self()</c> an anonymous
+ server is created just as when using
+ <seealso marker="#start_link/3"><c>start[_link]/3</c></seealso>.
+ If <c><anno>Server</anno></c> is a
+ <seealso marker="#type-server_name"><c>server_name()</c></seealso>
+ a named server is created just as when using
+ <seealso marker="#start_link/4"><c>start[_link]/4</c></seealso>.
However, the
<seealso marker="#type-server_name"><c>server_name()</c></seealso>
name must have been registered accordingly
- <em>before</em> this function is called.</p>
+ <em>before</em> this function is called.
+ </p>
<p>
- <c><anno>CallbackMode</anno></c>, <c><anno>State</anno></c>,
- <c><anno>Data</anno></c>, and <c><anno>Actions</anno></c>
+ <c><anno>State</anno></c>, <c><anno>Data</anno></c>,
+ and <c><anno>Actions</anno></c>
have the same meanings as in the return value of
<seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>.
- Also, the callback module <c><anno>Module</anno></c>
- does not need to export an <c>init/1</c> function.
+ Also, the callback module does not need to export a
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ function.
</p>
<p>
The function fails if the calling process was not started by a
@@ -1253,6 +1261,48 @@ handle_event(_, _, State, Data) ->
<funcs>
<func>
+ <name>Module:callback_mode() -> CallbackMode</name>
+ <fsummary>Update the internal state during upgrade/downgrade.</fsummary>
+ <type>
+ <v>
+ CallbackMode =
+ <seealso marker="#type-callback_mode">callback_mode()</seealso>
+ </v>
+ </type>
+ <desc>
+ <p>
+ This function is called by a <c>gen_statem</c>
+ when it needs to find out the
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
+ of the callback module. The value is cached by <c>gen_statem</c>
+ for efficiency reasons, so this function is only called
+ once after server start and after code change,
+ but before the first
+ <seealso marker="#state_function">state function</seealso>
+ is called. More occasions may be added in future versions
+ of <c>gen_statem</c>.
+ </p>
+ <p>
+ Server start happens either when
+ <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
+ returns or when
+ <seealso marker="#enter_loop/4"><c>enter_loop/4-6</c></seealso>
+ is called. Code change happens when
+ <seealso marker="#Module:code_change/4"><c>Module:code_change/4</c></seealso>
+ returns.
+ </p>
+ <note>
+ <p>
+ If this function's body does not consist of solely one of two
+ possible
+ <seealso marker="#type-callback_mode">atoms</seealso>
+ the callback module is doing something strange.
+ </p>
+ </note>
+ </desc>
+ </func>
+
+ <func>
<name>Module:code_change(OldVsn, OldState, OldData, Extra) ->
Result
</name>
@@ -1262,11 +1312,7 @@ handle_event(_, _, State, Data) ->
<v>&nbsp;&nbsp;Vsn = term()</v>
<v>OldState = NewState = term()</v>
<v>Extra = term()</v>
- <v>Result = {CallbackMode,NewState,NewData} | Reason</v>
- <v>
- CallbackMode =
- <seealso marker="#type-callback_mode">callback_mode()</seealso>
- </v>
+ <v>Result = {ok,NewState,NewData} | Reason</v>
<v>
OldState = NewState =
<seealso marker="#type-state">state()</seealso>
@@ -1295,21 +1341,6 @@ handle_event(_, _, State, Data) ->
<c>Module</c>. If no such attribute is defined, the version
is the checksum of the Beam file.
</p>
- <note>
- <p>
- If you would dare to change
- <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
- during release upgrade/downgrade, the upgrade is no problem,
- as the new code surely knows what <em>callback mode</em>
- it needs. However, for a downgrade this function must
- know from argument <c>Extra</c> that comes from the
- <seealso marker="sasl:appup"><c>sasl:appup</c></seealso>
- file what <em>callback mode</em> the old code did use.
- It can also be possible to figure this out
- from argument <c>{down,Vsn}</c>, as <c>Vsn</c>
- in effect defines the old callback module version.
- </p>
- </note>
<p>
<c>OldState</c> and <c>OldData</c> is the internal state
of the <c>gen_statem</c>.
@@ -1321,39 +1352,32 @@ handle_event(_, _, State, Data) ->
<p>
If successful, the function must return the updated
internal state in an
- <c>{CallbackMode,NewState,NewData}</c> tuple.
+ <c>{ok,NewState,NewData}</c> tuple.
</p>
<p>
If the function returns a failure <c>Reason</c>, the ongoing
upgrade fails and rolls back to the old release.
- Note that <c>Reason</c> can not be a 3-tuple since that
- will be regarded as a
- <c>{CallbackMode,NewState,NewData}</c> tuple,
+ Note that <c>Reason</c> can not be an <c>{ok,_,_}</c> tuple
+ since that will be regarded as a
+ <c>{ok,NewState,NewData}</c> tuple,
and that a tuple matching <c>{ok,_}</c>
- is an invalid failure <c>Reason</c>.
+ is an also invalid failure <c>Reason</c>.
It is recommended to use an atom as <c>Reason</c> since
it will be wrapped in an <c>{error,Reason}</c> tuple.
</p>
- <p>
- This function can use
- <seealso marker="erts:erlang#throw/1"><c>erlang:throw/1</c></seealso>
- to return <c>Result</c> or <c>Reason</c>.
- </p>
</desc>
</func>
<func>
<name>Module:init(Args) -> Result</name>
- <fsummary>Initialize process and internal state.</fsummary>
+ <fsummary>
+ Optional function for initializing process and internal state.
+ </fsummary>
<type>
<v>Args = term()</v>
- <v>Result = {CallbackMode,State,Data}</v>
- <v>&nbsp;| {CallbackMode,State,Data,Actions}</v>
+ <v>Result = {ok,State,Data}</v>
+ <v>&nbsp;| {ok,State,Data,Actions}</v>
<v>&nbsp;| {stop,Reason} | ignore</v>
- <v>
- CallbackMode =
- <seealso marker="#type-callback_mode">callback_mode()</seealso>
- </v>
<v>State = <seealso marker="#type-state">state()</seealso></v>
<v>
Data = <seealso marker="#type-data">data()</seealso>
@@ -1372,7 +1396,7 @@ handle_event(_, _, State, Data) ->
<seealso marker="#start_link/3"><c>start_link/3,4</c></seealso>
or
<seealso marker="#start/3"><c>start/3,4</c></seealso>,
- this function is called by the new process to initialize
+ this optional function is called by the new process to initialize
the implementation state and server data.
</p>
<p>
@@ -1381,11 +1405,8 @@ handle_event(_, _, State, Data) ->
</p>
<p>
If the initialization is successful, the function is to
- return <c>{CallbackMode,State,Data}</c> or
- <c>{CallbackMode,State,Data,Actions}</c>.
- <c>CallbackMode</c> selects the
- <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
- of the <c>gen_statem</c>.
+ return <c>{ok,State,Data}</c> or
+ <c>{ok,State,Data,Actions}</c>.
<c>State</c> is the initial
<seealso marker="#type-state"><c>state()</c></seealso>
and <c>Data</c> the initial server
@@ -1403,11 +1424,16 @@ handle_event(_, _, State, Data) ->
or <c>ignore</c>; see
<seealso marker="#start_link/3"><c>start_link/3,4</c></seealso>.
</p>
- <p>
- This function can use
- <seealso marker="erts:erlang#throw/1"><c>erlang:throw/1</c></seealso>
- to return <c>Result</c>.
- </p>
+ <note>
+ <p>
+ This callback is optional, so a callback module does not need
+ to export it, but most do. If this function is not exported,
+ the <c>gen_statem</c> should be started through
+ <seealso marker="proc_lib"><c>proc_lib</c></seealso>
+ and
+ <seealso marker="#enter_loop/4"><c>enter_loop/4-6</c></seealso>.
+ </p>
+ </note>
</desc>
</func>
@@ -1438,10 +1464,14 @@ handle_event(_, _, State, Data) ->
This callback is optional, so a callback module does not need
to export it. The <c>gen_statem</c> module provides a default
implementation of this function that returns
- <c>{State,Data}</c>. If this callback fails, the default
- function returns <c>{State,Info}</c>,
- where <c>Info</c> informs of the crash but no details,
- to hide possibly sensitive data.
+ <c>{State,Data}</c>.
+ </p>
+ <p>
+ If this callback is exported but fails,
+ to hide possibly sensitive data,
+ the default function will instead return <c>{State,Info}</c>,
+ where <c>Info</c> says nothing but the fact that
+ <c>format_status/2</c> has crashed.
</p>
</note>
<p>This function is called by a <c>gen_statem</c> process when
@@ -1502,11 +1532,6 @@ handle_event(_, _, State, Data) ->
printed in log files. Another use is to hide sensitive data from
being written to the error log.
</p>
- <p>
- This function can use
- <seealso marker="erts:erlang#throw/1"><c>erlang:throw/1</c></seealso>
- to return <c>Status</c>.
- </p>
</desc>
</func>
@@ -1581,9 +1606,12 @@ handle_event(_, _, State, Data) ->
see <seealso marker="#type-action"><c>action()</c></seealso>.
</p>
<p>
- These functions can use
- <seealso marker="erts:erlang#throw/1"><c>erlang:throw/1</c></seealso>,
- to return the result.
+ Note the fact that you can use
+ <seealso marker="erts:erlang#throw/1"><c>throw</c></seealso>
+ to return the result, which can be useful.
+ For example to bail out with <c>throw(keep_state_and_data)</c>
+ from deep within complex code that is in no position to
+ return <c>{next_state,State,Data}</c>.
</p>
</desc>
</func>
@@ -1656,11 +1684,6 @@ handle_event(_, _, State, Data) ->
and an error report is issued using
<seealso marker="kernel:error_logger#format/2"><c>error_logger:format/2</c></seealso>.
</p>
- <p>
- This function can use
- <seealso marker="erts:erlang#throw/1"><c>erlang:throw/1</c></seealso>
- to return <c>Ignored</c>, which is ignored anyway.
- </p>
</desc>
</func>
</funcs>
diff --git a/lib/stdlib/src/gen_statem.erl b/lib/stdlib/src/gen_statem.erl
index c02e6a1a19..3b3477b282 100644
--- a/lib/stdlib/src/gen_statem.erl
+++ b/lib/stdlib/src/gen_statem.erl
@@ -24,7 +24,7 @@
[start/3,start/4,start_link/3,start_link/4,
stop/1,stop/3,
cast/2,call/2,call/3,
- enter_loop/5,enter_loop/6,enter_loop/7,
+ enter_loop/4,enter_loop/5,enter_loop/6,
reply/1,reply/2]).
%% gen callbacks
@@ -63,8 +63,8 @@
{To :: pid(), Tag :: term()}. % Reply-to specifier for call
-type state() ::
- state_name() | % For state callback function StateName/5
- term(). % For state callback function handle_event/5
+ state_name() | % For StateName/3 callback functios
+ term(). % For handle_event/4 callback function
-type state_name() :: atom().
@@ -174,28 +174,33 @@
%% an {ok, ...} tuple. Thereafter the state callbacks are called
%% for all events to this server.
-callback init(Args :: term()) ->
- {callback_mode(), state(), data()} |
- {callback_mode(), state(), data(), [action()] | action()} |
+ {ok, state(), data()} |
+ {ok, state(), data(), [action()] | action()} |
'ignore' |
{'stop', Reason :: term()}.
-%% Example state callback for callback_mode() =:= state_functions
-%% state name 'state_name'.
+%% This callback shall return the callback mode of the callback module.
%%
-%% In this mode all states has to be type state_name() i.e atom().
+%% It is called once after init/0 and code_change/4 but before
+%% the first state callback StateName/3 or handle_event/4.
+-callback callback_mode() -> callback_mode().
+
+%% Example state callback for StateName = 'state_name'
+%% when callback_mode() =:= state_functions.
+%%
+%% In this mode all states has to be of type state_name() i.e atom().
%%
-%% Note that state callbacks and only state callbacks have arity 5
-%% and that is intended.
+%% Note that the only callbacks that have arity 3 are these
+%% StateName/3 callbacks and terminate/3, so the state name
+%% 'terminate' is unusable in this mode.
-callback state_name(
event_type(),
EventContent :: term(),
Data :: data()) ->
state_function_result().
%%
-%% State callback for callback_mode() =:= handle_event_function.
-%%
-%% Note that state callbacks and only state callbacks have arity 5
-%% and that is intended.
+%% State callback for all states
+%% when callback_mode() =:= handle_event_function.
-callback handle_event(
event_type(),
EventContent :: term(),
@@ -219,9 +224,7 @@
OldState :: state(),
OldData :: data(),
Extra :: term()) ->
- {CallbackMode :: callback_mode(),
- NewState :: state(),
- NewData :: data()} |
+ {ok, NewState :: state(), NewData :: data()} |
(Reason :: term()).
%% Format the callback module state in some sensible that is
@@ -240,10 +243,13 @@
[init/1, % One may use enter_loop/5,6,7 instead
format_status/2, % Has got a default implementation
%%
- state_name/3, % Example for callback_mode =:= state_functions:
- %% there has to be a StateName/5 callback function for every StateName.
+ state_name/3, % Example for callback_mode() =:= state_functions:
+ %% there has to be a StateName/3 callback function
+ %% for every StateName in your state machine but the state name
+ %% 'state_name' does of course not have to be used.
%%
- handle_event/4]). % For callback_mode =:= handle_event_function
+ handle_event/4 % For callback_mode() =:= handle_event_function
+ ]).
%% Type validation functions
callback_mode(CallbackMode) ->
@@ -451,43 +457,35 @@ reply({To,Tag}, Reply) when is_pid(To) ->
%% the same arguments as you would have returned from init/1
-spec enter_loop(
Module :: module(), Opts :: [debug_opt()],
- CallbackMode :: callback_mode(),
State :: state(), Data :: data()) ->
no_return().
-enter_loop(Module, Opts, CallbackMode, State, Data) ->
- enter_loop(Module, Opts, CallbackMode, State, Data, self()).
+enter_loop(Module, Opts, State, Data) ->
+ enter_loop(Module, Opts, State, Data, self()).
%%
-spec enter_loop(
Module :: module(), Opts :: [debug_opt()],
- CallbackMode :: callback_mode(),
State :: state(), Data :: data(),
Server_or_Actions ::
server_name() | pid() | [action()]) ->
no_return().
-enter_loop(Module, Opts, CallbackMode, State, Data, Server_or_Actions) ->
+enter_loop(Module, Opts, State, Data, Server_or_Actions) ->
if
is_list(Server_or_Actions) ->
- enter_loop(
- Module, Opts, CallbackMode, State, Data,
- self(), Server_or_Actions);
+ enter_loop(Module, Opts, State, Data, self(), Server_or_Actions);
true ->
- enter_loop(
- Module, Opts, CallbackMode, State, Data,
- Server_or_Actions, [])
+ enter_loop(Module, Opts, State, Data, Server_or_Actions, [])
end.
%%
-spec enter_loop(
Module :: module(), Opts :: [debug_opt()],
- CallbackMode :: callback_mode(),
State :: state(), Data :: data(),
Server :: server_name() | pid(),
Actions :: [action()] | action()) ->
no_return().
-enter_loop(Module, Opts, CallbackMode, State, Data, Server, Actions) ->
+enter_loop(Module, Opts, State, Data, Server, Actions) ->
is_atom(Module) orelse error({atom,Module}),
- callback_mode(CallbackMode) orelse error({callback_mode,CallbackMode}),
Parent = gen:get_parent(),
- enter(Module, Opts, CallbackMode, State, Data, Server, Actions, Parent).
+ enter(Module, Opts, State, Data, Server, Actions, Parent).
%%---------------------------------------------------------------------------
%% API helpers
@@ -515,7 +513,7 @@ send(Proc, Msg) ->
end.
%% Here the init_it/6 and enter_loop/5,6,7 functions converge
-enter(Module, Opts, CallbackMode, State, Data, Server, Actions, Parent) ->
+enter(Module, Opts, State, Data, Server, Actions, Parent) ->
%% The values should already have been type checked
Name = gen:get_proc_name(Server),
Debug = gen:debug_options(Name, Opts),
@@ -531,7 +529,7 @@ enter(Module, Opts, CallbackMode, State, Data, Server, Actions, Parent) ->
[Actions,{postpone,false}]
end,
S = #{
- callback_mode => CallbackMode,
+ callback_mode => undefined,
module => Module,
name => Name,
%% All fields below will be replaced according to the arguments to
@@ -559,9 +557,15 @@ init_it(Starter, Parent, ServerRef, Module, Args, Opts) ->
Result ->
init_result(Starter, Parent, ServerRef, Module, Result, Opts);
Class:Reason ->
+ Stacktrace = erlang:get_stacktrace(),
+ Name = gen:get_proc_name(ServerRef),
gen:unregister_name(ServerRef),
proc_lib:init_ack(Starter, {error,Reason}),
- erlang:raise(Class, Reason, erlang:get_stacktrace())
+ error_info(
+ Class, Reason, Stacktrace,
+ #{name => Name, callback_mode => undefined},
+ [], [], undefined),
+ erlang:raise(Class, Reason, Stacktrace)
end.
%%---------------------------------------------------------------------------
@@ -569,30 +573,12 @@ init_it(Starter, Parent, ServerRef, Module, Args, Opts) ->
init_result(Starter, Parent, ServerRef, Module, Result, Opts) ->
case Result of
- {CallbackMode,State,Data} ->
- case callback_mode(CallbackMode) of
- true ->
- proc_lib:init_ack(Starter, {ok,self()}),
- enter(
- Module, Opts, CallbackMode, State, Data,
- ServerRef, [], Parent);
- false ->
- Error = {callback_mode,CallbackMode},
- proc_lib:init_ack(Starter, {error,Error}),
- exit(Error)
- end;
- {CallbackMode,State,Data,Actions} ->
- case callback_mode(CallbackMode) of
- true ->
- proc_lib:init_ack(Starter, {ok,self()}),
- enter(
- Module, Opts, CallbackMode, State, Data,
- ServerRef, Actions, Parent);
- false ->
- Error = {callback_mode,CallbackMode},
- proc_lib:init_ack(Starter, {error,Error}),
- exit(Error)
- end;
+ {ok,State,Data} ->
+ proc_lib:init_ack(Starter, {ok,self()}),
+ enter(Module, Opts, State, Data, ServerRef, [], Parent);
+ {ok,State,Data,Actions} ->
+ proc_lib:init_ack(Starter, {ok,self()}),
+ enter(Module, Opts, State, Data, ServerRef, Actions, Parent);
{stop,Reason} ->
gen:unregister_name(ServerRef),
proc_lib:init_ack(Starter, {error,Reason}),
@@ -602,8 +588,14 @@ init_result(Starter, Parent, ServerRef, Module, Result, Opts) ->
proc_lib:init_ack(Starter, ignore),
exit(normal);
_ ->
- Error = {bad_return_value,Result},
+ Name = gen:get_proc_name(ServerRef),
+ gen:unregister_name(ServerRef),
+ Error = {bad_return_from_init,Result},
proc_lib:init_ack(Starter, {error,Error}),
+ error_info(
+ error, Error, ?STACKTRACE(),
+ #{name => Name, callback_mode => undefined},
+ [], [], undefined),
exit(Error)
end.
@@ -631,11 +623,9 @@ system_code_change(
Result -> Result
end
of
- {CallbackMode,NewState,NewData} ->
- callback_mode(CallbackMode) orelse
- error({callback_mode,CallbackMode}),
+ {ok,NewState,NewData} ->
{ok,
- S#{callback_mode := CallbackMode,
+ S#{callback_mode := undefined,
state := NewState,
data := NewData}};
{ok,_} = Error ->
@@ -676,14 +666,14 @@ format_status(
%% them, not as the real erlang messages. Use trace for that.
%%---------------------------------------------------------------------------
-print_event(Dev, {in,Event}, {Name,_}) ->
+print_event(Dev, {in,Event}, {Name,State}) ->
io:format(
- Dev, "*DBG* ~p received ~s~n",
- [Name,event_string(Event)]);
-print_event(Dev, {out,Reply,{To,_Tag}}, {Name,_}) ->
+ Dev, "*DBG* ~p receive ~s in state ~p~n",
+ [Name,event_string(Event),State]);
+print_event(Dev, {out,Reply,{To,_Tag}}, {Name,State}) ->
io:format(
- Dev, "*DBG* ~p sent ~p to ~p~n",
- [Name,Reply,To]);
+ Dev, "*DBG* ~p send ~p to ~p from state ~p~n",
+ [Name,Reply,To,State]);
print_event(Dev, {Tag,Event,NextState}, {Name,State}) ->
StateString =
case NextState of
@@ -875,22 +865,36 @@ loop_event(
%%
try
case CallbackMode of
+ undefined ->
+ Module:callback_mode();
state_functions ->
- Module:State(Type, Content, Data);
+ erlang:apply(Module, State, [Type,Content,Data]);
handle_event_function ->
Module:handle_event(Type, Content, State, Data)
- end of
+ end
+ of
+ Result when CallbackMode =:= undefined ->
+ loop_event_callback_mode(
+ Parent, Debug, S, Events, State, Data, P, Event, Result);
Result ->
loop_event_result(
Parent, Debug, S, Events, State, Data, P, Event, Result)
catch
+ Result when CallbackMode =:= undefined ->
+ loop_event_callback_mode(
+ Parent, Debug, S, Events, State, Data, P, Event, Result);
Result ->
loop_event_result(
Parent, Debug, S, Events, State, Data, P, Event, Result);
- error:badarg when CallbackMode =:= state_functions ->
+ error:badarg ->
case erlang:get_stacktrace() of
- [{erlang,apply,[Module,State,_],_}|Stacktrace] ->
- Args = [Type,Content,Data],
+ [{erlang,apply,
+ [Module,State,[Type,Content,Data]=Args],
+ _}
+ |Stacktrace]
+ when CallbackMode =:= state_functions ->
+ %% We get here e.g if apply fails
+ %% due to State not being an atom
terminate(
error,
{undef_state_function,{Module,State,Args}},
@@ -902,24 +906,29 @@ loop_event(
Debug, S, [Event|Events], State, Data, P)
end;
error:undef ->
- %% Process an undef to check for the simple mistake
+ %% Process undef to check for the simple mistake
%% of calling a nonexistent state function
+ %% to make the undef more precise
case erlang:get_stacktrace() of
- [{Module,State,
- [Type,Content,Data]=Args,
- _}
+ [{Module,callback_mode,[]=Args,_}
+ |Stacktrace]
+ when CallbackMode =:= undefined ->
+ terminate(
+ error,
+ {undef_callback,{Module,callback_mode,Args}},
+ Stacktrace,
+ Debug, S, [Event|Events], State, Data, P);
+ [{Module,State,[Type,Content,Data]=Args,_}
|Stacktrace]
- when CallbackMode =:= state_functions ->
+ when CallbackMode =:= state_functions ->
terminate(
error,
{undef_state_function,{Module,State,Args}},
Stacktrace,
Debug, S, [Event|Events], State, Data, P);
- [{Module,handle_event,
- [Type,Content,State,Data]=Args,
- _}
+ [{Module,handle_event,[Type,Content,State,Data]=Args,_}
|Stacktrace]
- when CallbackMode =:= handle_event_function ->
+ when CallbackMode =:= handle_event_function ->
terminate(
error,
{undef_state_function,{Module,handle_event,Args}},
@@ -937,6 +946,25 @@ loop_event(
Debug, S, [Event|Events], State, Data, P)
end.
+%% Interpret callback_mode() result
+loop_event_callback_mode(
+ Parent, Debug, S, Events, State, Data, P, Event, CallbackMode) ->
+ case callback_mode(CallbackMode) of
+ true ->
+ Hibernate = false, % We have already GC:ed recently
+ loop_event(
+ Parent, Debug,
+ S#{callback_mode := CallbackMode},
+ Events,
+ State, Data, P, Event, Hibernate);
+ false ->
+ terminate(
+ error,
+ {bad_return_from_callback_mode,CallbackMode},
+ ?STACKTRACE(),
+ Debug, S, [Event|Events], State, Data, P)
+ end.
+
%% Interpret all callback return variants
loop_event_result(
Parent, Debug, S, Events, State, Data, P, Event, Result) ->
@@ -989,7 +1017,9 @@ loop_event_result(
State, Data, P, Event, State, Actions);
_ ->
terminate(
- error, {bad_return_value,Result}, ?STACKTRACE(),
+ error,
+ {bad_return_from_state_function,Result},
+ ?STACKTRACE(),
Debug, S, [Event|Events], State, Data, P)
end.
@@ -1026,20 +1056,26 @@ loop_event_actions(
Postpone, Hibernate, Timeout, NextEvents);
false ->
terminate(
- error, {bad_action,Action}, ?STACKTRACE(),
+ error,
+ {bad_action_from_state_function,Action},
+ ?STACKTRACE(),
Debug, S, [Event|Events], State, NewData, P)
end;
{next_event,Type,Content} ->
case event_type(Type) of
true ->
+ NewDebug =
+ sys_debug(Debug, S, State, {in,{Type,Content}}),
loop_event_actions(
- Parent, Debug, S, Events,
+ Parent, NewDebug, S, Events,
State, NewData, P, Event, NextState, Actions,
Postpone, Hibernate, Timeout,
[{Type,Content}|NextEvents]);
false ->
terminate(
- error, {bad_action,Action}, ?STACKTRACE(),
+ error,
+ {bad_action_from_state_function,Action},
+ ?STACKTRACE(),
Debug, S, [Event|Events], State, NewData, P)
end;
%% Actions that set options
@@ -1050,7 +1086,9 @@ loop_event_actions(
NewPostpone, Hibernate, Timeout, NextEvents);
{postpone,_} ->
terminate(
- error, {bad_action,Action}, ?STACKTRACE(),
+ error,
+ {bad_action_from_state_function,Action},
+ ?STACKTRACE(),
Debug, S, [Event|Events], State, NewData, P);
postpone ->
loop_event_actions(
@@ -1064,7 +1102,9 @@ loop_event_actions(
Postpone, NewHibernate, Timeout, NextEvents);
{hibernate,_} ->
terminate(
- error, {bad_action,Action}, ?STACKTRACE(),
+ error,
+ {bad_action_from_state_function,Action},
+ ?STACKTRACE(),
Debug, S, [Event|Events], State, NewData, P);
hibernate ->
loop_event_actions(
@@ -1083,7 +1123,9 @@ loop_event_actions(
Postpone, Hibernate, NewTimeout, NextEvents);
{timeout,_,_} ->
terminate(
- error, {bad_action,Action}, ?STACKTRACE(),
+ error,
+ {bad_action_from_state_function,Action},
+ ?STACKTRACE(),
Debug, S, [Event|Events], State, NewData, P);
infinity -> % Clear timer - it will never trigger
loop_event_actions(
@@ -1098,7 +1140,9 @@ loop_event_actions(
Postpone, Hibernate, NewTimeout, NextEvents);
_ ->
terminate(
- error, {bad_action,Action}, ?STACKTRACE(),
+ error,
+ {bad_action_from_state_function,Action},
+ ?STACKTRACE(),
Debug, S, [Event|Events], State, NewData, P)
end;
%%
@@ -1170,7 +1214,9 @@ do_reply_then_terminate(
NewDebug, S, Q, State, Data, P, Rs);
_ ->
terminate(
- error, {bad_action,R}, ?STACKTRACE(),
+ error,
+ {bad_reply_action_from_state_function,R},
+ ?STACKTRACE(),
Debug, S, Q, State, Data, P)
end.
@@ -1189,8 +1235,9 @@ terminate(
C:R ->
ST = erlang:get_stacktrace(),
error_info(
- C, R, ST, Debug, S, Q, P,
+ C, R, ST, S, Q, P,
format_status(terminate, get(), S, State, Data)),
+ sys:print_log(Debug),
erlang:raise(C, R, ST)
end,
case Reason of
@@ -1199,8 +1246,9 @@ terminate(
{shutdown,_} -> ok;
_ ->
error_info(
- Class, Reason, Stacktrace, Debug, S, Q, P,
- format_status(terminate, get(), S, State, Data))
+ Class, Reason, Stacktrace, S, Q, P,
+ format_status(terminate, get(), S, State, Data)),
+ sys:print_log(Debug)
end,
case Stacktrace of
[] ->
@@ -1210,7 +1258,7 @@ terminate(
end.
error_info(
- Class, Reason, Stacktrace, Debug,
+ Class, Reason, Stacktrace,
#{name := Name, callback_mode := CallbackMode},
Q, P, FmtData) ->
{FixedReason,FixedStacktrace} =
@@ -1277,9 +1325,7 @@ error_info(
case FixedStacktrace of
[] -> [];
_ -> [FixedStacktrace]
- end),
- sys:print_log(Debug),
- ok.
+ end).
%% Call Module:format_status/2 or return a default value
@@ -1292,7 +1338,7 @@ format_status(Opt, PDict, #{module := Module}, State, Data) ->
_:_ ->
format_status_default(
Opt, State,
- "Module:format_status/2 crashed")
+ atom_to_list(Module) ++ ":format_status/2 crashed")
end;
false ->
format_status_default(Opt, State, Data)
@@ -1300,10 +1346,10 @@ format_status(Opt, PDict, #{module := Module}, State, Data) ->
%% The default Module:format_status/2
format_status_default(Opt, State, Data) ->
- SSD = {State,Data},
+ StateData = {State,Data},
case Opt of
terminate ->
- SSD;
+ StateData;
_ ->
- [{data,[{"State",SSD}]}]
+ [{data,[{"State",StateData}]}]
end.
diff --git a/lib/stdlib/test/gen_statem_SUITE.erl b/lib/stdlib/test/gen_statem_SUITE.erl
index 364314f91b..1d1417c2e6 100644
--- a/lib/stdlib/test/gen_statem_SUITE.erl
+++ b/lib/stdlib/test/gen_statem_SUITE.erl
@@ -37,33 +37,32 @@ all() ->
{group, stop_handle_event},
{group, abnormal},
{group, abnormal_handle_event},
- shutdown, stop_and_reply, event_order,
+ shutdown, stop_and_reply, event_order, code_change,
{group, sys},
hibernate, enter_loop].
groups() ->
- [{start, [],
- [start1, start2, start3, start4, start5, start6, start7,
- start8, start9, start10, start11, start12, next_events]},
- {start_handle_event, [],
- [start1, start2, start3, start4, start5, start6, start7,
- start8, start9, start10, start11, start12, next_events]},
- {stop, [],
- [stop1, stop2, stop3, stop4, stop5, stop6, stop7, stop8, stop9, stop10]},
- {stop_handle_event, [],
- [stop1, stop2, stop3, stop4, stop5, stop6, stop7, stop8, stop9, stop10]},
- {abnormal, [], [abnormal1, abnormal2]},
- {abnormal_handle_event, [], [abnormal1, abnormal2]},
- {sys, [],
- [sys1, code_change,
- call_format_status,
- error_format_status, terminate_crash_format,
- get_state, replace_state]},
- {sys_handle_event, [],
- [sys1,
- call_format_status,
- error_format_status, terminate_crash_format,
- get_state, replace_state]}].
+ [{start, [], tcs(start)},
+ {start_handle_event, [], tcs(start)},
+ {stop, [], tcs(stop)},
+ {stop_handle_event, [], tcs(stop)},
+ {abnormal, [], tcs(abnormal)},
+ {abnormal_handle_event, [], tcs(abnormal)},
+ {sys, [], tcs(sys)},
+ {sys_handle_event, [], tcs(sys)}].
+
+tcs(start) ->
+ [start1, start2, start3, start4, start5, start6, start7,
+ start8, start9, start10, start11, start12, next_events];
+tcs(stop) ->
+ [stop1, stop2, stop3, stop4, stop5, stop6, stop7, stop8, stop9, stop10];
+tcs(abnormal) ->
+ [abnormal1, abnormal2];
+tcs(sys) ->
+ [sys1, call_format_status,
+ error_format_status, terminate_crash_format,
+ get_state, replace_state].
+
init_per_suite(Config) ->
Config.
@@ -461,10 +460,10 @@ abnormal2(Config) ->
{ok,Pid} = gen_statem:start_link(?MODULE, start_arg(Config, []), []),
%% bad return value in the gen_statem loop
- {{bad_return_value,badreturn},_} =
+ {{bad_return_from_state_function,badreturn},_} =
?EXPECT_FAILURE(gen_statem:call(Pid, badreturn), Reason),
receive
- {'EXIT',Pid,{bad_return_value,badreturn}} -> ok
+ {'EXIT',Pid,{bad_return_from_state_function,badreturn}} -> ok
after 5000 ->
ct:fail(gen_statem_did_not_die)
end,
@@ -633,11 +632,13 @@ sys1(Config) ->
sys:resume(Pid),
stop_it(Pid).
-code_change(Config) ->
- Mode = handle_event_function,
- {ok,Pid} = gen_statem:start(?MODULE, start_arg(Config, []), []),
+code_change(_Config) ->
+ {ok,Pid} =
+ gen_statem:start(
+ ?MODULE, {callback_mode,state_functions,[]}, []),
{idle,data} = sys:get_state(Pid),
sys:suspend(Pid),
+ Mode = handle_event_function,
sys:change_code(Pid, ?MODULE, old_vsn, Mode),
sys:resume(Pid),
{idle,{old_vsn,data,Mode}} = sys:get_state(Pid),
@@ -708,7 +709,7 @@ error_format_status(Config) ->
gen_statem:start(
?MODULE, start_arg(Config, {data,Data}), []),
%% bad return value in the gen_statem loop
- {{bad_return_value,badreturn},_} =
+ {{bad_return_from_state_function,badreturn},_} =
?EXPECT_FAILURE(gen_statem:call(Pid, badreturn), Reason),
receive
{error,_,
@@ -716,7 +717,7 @@ error_format_status(Config) ->
"** State machine"++_,
[Pid,{{call,_},badreturn},
{formatted,idle,Data},
- error,{bad_return_value,badreturn}|_]}} ->
+ error,{bad_return_from_state_function,badreturn}|_]}} ->
ok;
Other when is_tuple(Other), element(1, Other) =:= error ->
error_logger_forwarder:unregister(),
@@ -1029,11 +1030,7 @@ enter_loop(_Config) ->
end,
%% Process not started using proc_lib
- CallbackMode = state_functions,
- Pid4 =
- spawn_link(
- gen_statem, enter_loop,
- [?MODULE,[],CallbackMode,state0,[]]),
+ Pid4 = spawn_link(gen_statem, enter_loop, [?MODULE,[],state0,[]]),
receive
{'EXIT',Pid4,process_was_not_started_by_proc_lib} ->
ok
@@ -1107,21 +1104,18 @@ enter_loop(Reg1, Reg2) ->
anon -> ignore
end,
proc_lib:init_ack({ok, self()}),
- CallbackMode = state_functions,
case Reg2 of
local ->
gen_statem:enter_loop(
- ?MODULE, [], CallbackMode, state0, [], {local,armitage});
+ ?MODULE, [], state0, [], {local,armitage});
global ->
gen_statem:enter_loop(
- ?MODULE, [], CallbackMode, state0, [], {global,armitage});
+ ?MODULE, [], state0, [], {global,armitage});
via ->
gen_statem:enter_loop(
- ?MODULE, [], CallbackMode, state0, [],
- {via, dummy_via, armitage});
+ ?MODULE, [], state0, [], {via, dummy_via, armitage});
anon ->
- gen_statem:enter_loop(
- ?MODULE, [], CallbackMode, state0, [])
+ gen_statem:enter_loop(?MODULE, [], state0, [])
end.
@@ -1266,33 +1260,39 @@ init(stop_shutdown) ->
{stop,shutdown};
init(sleep) ->
?t:sleep(1000),
- {state_functions,idle,data};
+ {ok,idle,data};
init(hiber) ->
- {state_functions,hiber_idle,[]};
+ {ok,hiber_idle,[]};
init(hiber_now) ->
- {state_functions,hiber_idle,[],[hibernate]};
+ {ok,hiber_idle,[],[hibernate]};
init({data, Data}) ->
- {state_functions,idle,Data};
+ {ok,idle,Data};
init({callback_mode,CallbackMode,Arg}) ->
- case init(Arg) of
- {_,State,Data,Ops} ->
- {CallbackMode,State,Data,Ops};
- {_,State,Data} ->
- {CallbackMode,State,Data};
- Other ->
- Other
- end;
+ ets:new(?MODULE, [named_table,private]),
+ ets:insert(?MODULE, {callback_mode,CallbackMode}),
+ init(Arg);
init({map_statem,#{init := Init}=Machine}) ->
+ ets:new(?MODULE, [named_table,private]),
+ ets:insert(?MODULE, {callback_mode,handle_event_function}),
case Init() of
{ok,State,Data,Ops} ->
- {handle_event_function,State,[Data|Machine],Ops};
+ {ok,State,[Data|Machine],Ops};
{ok,State,Data} ->
- {handle_event_function,State,[Data|Machine]};
+ {ok,State,[Data|Machine]};
Other ->
Other
end;
init([]) ->
- {state_functions,idle,data}.
+ {ok,idle,data}.
+
+callback_mode() ->
+ try ets:lookup(?MODULE, callback_mode) of
+ [{callback_mode,CallbackMode}] ->
+ CallbackMode
+ catch
+ error:badarg ->
+ state_functions
+ end.
terminate(_, _State, crash_terminate) ->
exit({crash,terminate});
@@ -1568,7 +1568,12 @@ wrap_result(Result) ->
code_change(OldVsn, State, Data, CallbackMode) ->
- {CallbackMode,State,{OldVsn,Data,CallbackMode}}.
+ io:format(
+ "code_change(~p, ~p, ~p, ~p)~n", [OldVsn,State,Data,CallbackMode]),
+ ets:insert(?MODULE, {callback_mode,CallbackMode}),
+ io:format(
+ "code_change(~p, ~p, ~p, ~p)~n", [OldVsn,State,Data,CallbackMode]),
+ {ok,State,{OldVsn,Data,CallbackMode}}.
format_status(terminate, [_Pdict,State,Data]) ->
{formatted,State,Data};
diff --git a/lib/tools/doc/src/erlang_mode.xml b/lib/tools/doc/src/erlang_mode.xml
index 00cf5196b4..7fef74813b 100644
--- a/lib/tools/doc/src/erlang_mode.xml
+++ b/lib/tools/doc/src/erlang_mode.xml
@@ -252,7 +252,14 @@
behavior</item>
<item>gen_event - skeleton for the OTP gen_event behavior</item>
<item>gen_fsm - skeleton for the OTP gen_fsm behavior</item>
- <item>gen_statem - skeleton for the OTP gen_statem behavior</item>
+ <item>
+ gen_statem (StateName/3) - skeleton for the OTP gen_statem behavior
+ using state name functions
+ </item>
+ <item>
+ gen_statem (handle_event/4) - skeleton for the OTP gen_statem behavior
+ using one state function
+ </item>
<item>Library module - skeleton for a module that does not
implement a process.</item>
<item>Corba callback - skeleton for a Corba callback module.</item>
diff --git a/lib/tools/emacs/erlang-skels.el b/lib/tools/emacs/erlang-skels.el
index c1152f31a4..0284c9d686 100644
--- a/lib/tools/emacs/erlang-skels.el
+++ b/lib/tools/emacs/erlang-skels.el
@@ -56,8 +56,10 @@
erlang-skel-gen-event erlang-skel-header)
("gen_fsm" "gen-fsm"
erlang-skel-gen-fsm erlang-skel-header)
- ("gen_statem" "gen-statem"
- erlang-skel-gen-statem erlang-skel-header)
+ ("gen_statem (StateName/3)" "gen-statem-StateName"
+ erlang-skel-gen-statem-StateName erlang-skel-header)
+ ("gen_statem (handle_event/4)" "gen-statem-handle-event"
+ erlang-skel-gen-statem-handle-event erlang-skel-header)
("wx_object" "wx-object"
erlang-skel-wx-object erlang-skel-header)
("Library module" "gen-lib"
@@ -497,6 +499,7 @@ Please see the function `tempo-define-template'.")
"%% {stop, Reason}" n
(erlang-skel-separator-end 2)
"init([]) ->" n>
+ "process_flag(trap_exit, true)," n>
"{ok, #state{}}." n
n
(erlang-skel-separator-start 2)
@@ -740,6 +743,7 @@ Please see the function `tempo-define-template'.")
"%% {stop, StopReason}" n
(erlang-skel-separator-end 2)
"init([]) ->" n>
+ "process_flag(trap_exit, true)," n>
"{ok, state_name, #state{}}." n
n
(erlang-skel-separator-start 2)
@@ -860,7 +864,7 @@ Please see the function `tempo-define-template'.")
"*The template of a gen_fsm.
Please see the function `tempo-define-template'.")
-(defvar erlang-skel-gen-statem
+(defvar erlang-skel-gen-statem-StateName
'((erlang-skel-include erlang-skel-large-header)
"-behaviour(gen_statem)." n n
@@ -868,9 +872,8 @@ Please see the function `tempo-define-template'.")
"-export([start_link/0])." n
n
"%% gen_statem callbacks" n
- "-export([init/1, terminate/3, code_change/4])." n
+ "-export([callback_mode/0, init/1, terminate/3, code_change/4])." n
"-export([state_name/3])." n
- "-export([handle_event/4])." n
n
"-define(SERVER, ?MODULE)." n
n
@@ -899,30 +902,38 @@ Please see the function `tempo-define-template'.")
(erlang-skel-separator-start 2)
"%% @private" n
"%% @doc" n
+ "%% Define the callback_mode() for this callback module." n
+ (erlang-skel-separator-end 2)
+ "-spec callback_mode() -> gen_statem:callback_mode()." n
+ "callback_mode() -> state_functions." n
+ n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
"%% Whenever a gen_statem is started using gen_statem:start/[3,4] or" n
"%% gen_statem:start_link/[3,4], this function is called by the new" n
"%% process to initialize." n
(erlang-skel-separator-end 2)
"-spec init(Args :: term()) ->" n>
- "{gen_statem:callback_mode()," n>
- "State :: term(), Data :: term()} |" n>
- "{gen_statem:callback_mode()," n>
- "State :: term(), Data :: term()," n>
+ "{ok, State :: term(), Data :: term()} |" n>
+ "{ok, State :: term(), Data :: term()," n>
"[gen_statem:action()] | gen_statem:action()} |" n>
"ignore |" n>
"{stop, Reason :: term()}." n
"init([]) ->" n>
- "{state_functions, state_name, #data{}}." n
+ "process_flag(trap_exit, true)," n>
+ "{ok, state_name, #data{}}." n
n
(erlang-skel-separator-start 2)
"%% @private" n
"%% @doc" n
- "%% If the gen_statem runs with CallbackMode =:= state_functions" n
- "%% there should be one instance of this function for each possible" n
- "%% state name. Whenever a gen_statem receives an event," n
- "%% the instance of this function with the same name" n
- "%% as the current state name StateName is called to" n
- "%% handle the event." n
+ "%% There should be one function like this for each state name." n
+ "%% Whenever a gen_statem receives an event, the function " n
+ "%% with the name of the current state (StateName) " n
+ "%% is called to handle the event." n
+ "%%" n
+ "%% NOTE: If there is an exported function handle_event/4, it is called" n
+ "%% instead of StateName/3 functions like this!" n
(erlang-skel-separator-end 2)
"-spec state_name(" n>
"gen_statem:event_type(), Msg :: term()," n>
@@ -934,8 +945,103 @@ Please see the function `tempo-define-template'.")
(erlang-skel-separator-start 2)
"%% @private" n
"%% @doc" n
- "%% If the gen_statem runs with CallbackMode =:= handle_event_function" n
- "%% this function is called for every event a gen_statem receives." n
+ "%% This function is called by a gen_statem when it is about to" n
+ "%% terminate. It should be the opposite of Module:init/1 and do any" n
+ "%% necessary cleaning up. When it returns, the gen_statem terminates with" n
+ "%% Reason. The return value is ignored." n
+ (erlang-skel-separator-end 2)
+ "-spec terminate(Reason :: term(), State :: term(), Data :: term()) ->" n>
+ "any()." n
+ "terminate(_Reason, _State, _Data) ->" n>
+ "void." n
+ n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% Convert process state when code is changed" n
+ (erlang-skel-separator-end 2)
+ "-spec code_change(" n>
+ "OldVsn :: term() | {down,term()}," n>
+ "State :: term(), Data :: term(), Extra :: term()) ->" n>
+ "{ok, NewState :: term(), NewData :: term()} |" n>
+ "(Reason :: term())." n
+ "code_change(_OldVsn, State, Data, _Extra) ->" n>
+ "{ok, State, Data}." n
+ n
+ (erlang-skel-double-separator-start 3)
+ "%%% Internal functions" n
+ (erlang-skel-double-separator-end 3)
+ )
+ "*The template of a gen_statem (StateName/3).
+Please see the function `tempo-define-template'.")
+
+(defvar erlang-skel-gen-statem-handle-event
+ '((erlang-skel-include erlang-skel-large-header)
+ "-behaviour(gen_statem)." n n
+
+ "%% API" n
+ "-export([start_link/0])." n
+ n
+ "%% gen_statem callbacks" n
+ "-export([callback_mode/0, init/1, terminate/3, code_change/4])." n
+ "-export([handle_event/4])." n
+ n
+ "-define(SERVER, ?MODULE)." n
+ n
+ "-record(data, {})." n
+ n
+ (erlang-skel-double-separator-start 3)
+ "%%% API" n
+ (erlang-skel-double-separator-end 3) n
+ (erlang-skel-separator-start 2)
+ "%% @doc" n
+ "%% Creates a gen_statem process which calls Module:init/1 to" n
+ "%% initialize. To ensure a synchronized start-up procedure, this" n
+ "%% function does not return until Module:init/1 has returned." n
+ "%%" n
+ (erlang-skel-separator-end 2)
+ "-spec start_link() ->" n>
+ "{ok, Pid :: pid()} |" n>
+ "ignore |" n>
+ "{error, Error :: term()}." n
+ "start_link() ->" n>
+ "gen_statem:start_link({local, ?SERVER}, ?MODULE, [], [])." n
+ n
+ (erlang-skel-double-separator-start 3)
+ "%%% gen_statem callbacks" n
+ (erlang-skel-double-separator-end 3) n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% Define the callback_mode() for this callback module." n
+ (erlang-skel-separator-end 2)
+ "-spec callback_mode() -> gen_statem:callback_mode()." n
+ "callback_mode() -> handle_event_function." n
+ n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% Whenever a gen_statem is started using gen_statem:start/[3,4] or" n
+ "%% gen_statem:start_link/[3,4], this function is called by the new" n
+ "%% process to initialize." n
+ (erlang-skel-separator-end 2)
+ "-spec init(Args :: term()) ->" n>
+ "{ok, State :: term(), Data :: term()} |" n>
+ "{ok, State :: term(), Data :: term()," n>
+ "[gen_statem:action()] | gen_statem:action()} |" n>
+ "ignore |" n>
+ "{stop, Reason :: term()}." n
+ "init([]) ->" n>
+ "process_flag(trap_exit, true)," n>
+ "{ok, state_name, #data{}}." n
+ n
+ (erlang-skel-separator-start 2)
+ "%% @private" n
+ "%% @doc" n
+ "%% This function is called for every event a gen_statem receives." n
+ "%%" n
+ "%% NOTE: If there is no exported function handle_event/4," n
+ "%% StateName/3 functions are called instead!" n
(erlang-skel-separator-end 2)
"-spec handle_event(" n>
"gen_statem:event_type(), Msg :: term()," n>
@@ -965,17 +1071,16 @@ Please see the function `tempo-define-template'.")
"-spec code_change(" n>
"OldVsn :: term() | {down,term()}," n>
"State :: term(), Data :: term(), Extra :: term()) ->" n>
- "{gen_statem:callback_mode()," n>
- "NewState :: term(), NewData :: term()} |" n>
+ "{ok, NewState :: term(), NewData :: term()} |" n>
"(Reason :: term())." n
"code_change(_OldVsn, State, Data, _Extra) ->" n>
- "{state_functions, State, Data}." n
+ "{ok, State, Data}." n
n
(erlang-skel-double-separator-start 3)
"%%% Internal functions" n
(erlang-skel-double-separator-end 3)
)
- "*The template of a gen_statem.
+ "*The template of a gen_statem (handle_event/4).
Please see the function `tempo-define-template'.")
(defvar erlang-skel-wx-object
diff --git a/system/doc/design_principles/statem.xml b/system/doc/design_principles/statem.xml
index aea623851a..f785ca9650 100644
--- a/system/doc/design_principles/statem.xml
+++ b/system/doc/design_principles/statem.xml
@@ -52,7 +52,7 @@
<section>
<title>Event-Driven State Machines</title>
<p>
- Established Automata theory does not deal much with
+ 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
@@ -226,11 +226,10 @@ handle_event(EventType, EventContent, State, Data) ->
-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([init/1,callback_mode/0,terminate/3,code_change/4]).
-export([locked/3,open/3]).
start_link(Code) ->
@@ -242,7 +241,10 @@ button(Digit) ->
init(Code) ->
do_lock(),
Data = #{code => Code, remaining => Code},
- {?CALLBACK_MODE,locked,Data}.
+ {ok,locked,Data}.
+
+callback_mode() ->
+ state_functions.
locked(
cast, {button,Digit},
@@ -273,7 +275,7 @@ terminate(_Reason, State, _Data) ->
State =/= locked andalso do_lock(),
ok.
code_change(_Vsn, State, Data, _Extra) ->
- {?CALLBACK_MODE,State,Data}.
+ {ok,State,Data}.
]]></code>
<p>The code is explained in the next sections.</p>
</section>
@@ -343,14 +345,8 @@ start_link(Code) ->
<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>,
+ This function is expected to return <c>{ok,State,Data}</c>,
+ where <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>
@@ -359,11 +355,12 @@ start_link(Code) ->
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}.
+ {ok,locked,Data}.
]]></code>
<p>Function
<seealso marker="stdlib:gen_statem#start_link/3"><c>gen_statem:start_link</c></seealso>
@@ -380,6 +377,21 @@ init(Code) ->
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>
+
+ <code type="erl"><![CDATA[
+callback_mode() ->
+ state_functions.
+ ]]></code>
+ <p>
+ Function
+ <seealso marker="stdlib:gen_statem#Module:callback_mode/0"><c>Module:callback_mode/0</c></seealso>
+ selects the
+ <seealso marker="#callback_modes"><c>CallbackMode</c></seealso>
+ for the callback module, in this case
+ <seealso marker="stdlib:gen_statem#type-callback_mode"><c>state_functions</c></seealso>.
+ That is, each state has got its own handler function.
+ </p>
+
</section>
<!-- =================================================================== -->
@@ -533,12 +545,11 @@ handle_event({call,From}, code_length, #{code := Code} = Data) ->
</p>
<code type="erl"><![CDATA[
...
--define(CALLBACK_MODE, handle_event_function).
-
-...
-export([handle_event/4]).
...
+callback_mode() ->
+ handle_event_function.
handle_event(cast, {button,Digit}, State, #{code := Code} = Data) ->
case State of
@@ -597,7 +608,7 @@ init(Args) ->
callback function <c>terminate(shutdown, State, Data)</c>.
</p>
<p>
- In the following example, function <c>terminate/3</c>
+ In this 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>
@@ -962,16 +973,13 @@ do_unlock() ->
</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).
+ enter(ok, locked, Data).
-...
+callback_mode() ->
+ state_functions.
locked(internal, enter, _Data) ->
do_lock(),
@@ -1027,11 +1035,10 @@ enter(Tag, State, Data) ->
-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([init/1,callback_mode/0,terminate/3,code_change/4]).
-export([locked/3,open/3]).
start_link(Code) ->
@@ -1047,7 +1054,10 @@ code_length() ->
init(Code) ->
process_flag(trap_exit, true),
Data = #{code => Code},
- enter(?CALLBACK_MODE, locked, Data).
+ enter(ok, locked, Data).
+
+callback_mode() ->
+ state_functions.
locked(internal, enter, #{code := Code} = Data) ->
do_lock(),
@@ -1091,7 +1101,7 @@ terminate(_Reason, State, _Data) ->
State =/= locked andalso do_lock(),
ok.
code_change(_Vsn, State, Data, _Extra) ->
- {?CALLBACK_MODE,State,Data}.
+ {ok,State,Data}.
]]></code>
</section>
@@ -1106,12 +1116,11 @@ code_change(_Vsn, State, Data, _Extra) ->
</p>
<code type="erl"><![CDATA[
...
--define(CALLBACK_MODE, handle_event_function).
-
-...
-export([handle_event/4]).
...
+callback_mode() ->
+ handle_event_function.
%% State: locked
handle_event(internal, enter, locked, #{code := Code} = Data) ->
@@ -1208,7 +1217,8 @@ format_status(Opt, [_PDict,State,Data]) ->
<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>.
+ the <c>Data</c> term, that is, <c>StateData = {State,Data}</c>,
+ in this example containing sensitive information.
</p>
</section>
@@ -1273,11 +1283,10 @@ format_status(Opt, [_PDict,State,Data]) ->
-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([init/1,callback_mode/0,terminate/3,code_change/4,format_status/2]).
-export([handle_event/4]).
start_link(Code, LockButton) ->
@@ -1296,7 +1305,10 @@ 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, []).
+ enter(ok, {locked,LockButton}, Data, []).
+
+callback_mode() ->
+ handle_event_function.
handle_event(
{call,From}, {set_lock_button,NewLockButton},
@@ -1366,7 +1378,7 @@ terminate(_Reason, State, _Data) ->
State =/= locked andalso do_lock(),
ok.
code_change(_Vsn, State, Data, _Extra) ->
- {?CALLBACK_MODE,State,Data}.
+ {ok,State,Data}.
format_status(Opt, [_PDict,State,Data]) ->
StateData =
{State,
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-17 20:48:45 +0000