Merge pull request atomvm#495 from fadushin/gen_statem-start_link

Add start_link/3,4 to gen_statem

This PR adds support for the gen_statem start_link function, so that gen_statem
implementations can work with supervisors.

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

libs/estdlib/src/gen_statem.erl

@@ -42,7 +42,9 @@
 %%-----------------------------------------------------------------------------
 -module(gen_statem).
 
--export([start/3, start/4, stop/1, stop/3, call/2, call/3, cast/2, reply/2]).
+-export([
+    start/3, start/4, start_link/3, start_link/4, stop/1, stop/3, call/2, call/3, cast/2, reply/2
+]).
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2]).
 
 -record(state, {
@@ -98,6 +100,53 @@ start({local, Name} = ServerName, Module, Args, Options) when is_atom(Name) ->
 start(Module, Args, Options) ->
     gen_server:start(?MODULE, {Module, Args}, Options).
 
+%%-----------------------------------------------------------------------------
+%% @param   ServerName the name with which to register the gen_statem
+%% @param   Module the module in which the gen_statem callbacks are defined
+%% @param   Args the arguments to pass to the module's init callback
+%% @param   Options the options used to create the gen_statem
+%% @returns the gen_statem pid, if successful; {error, Reason}, otherwise.
+%% @doc     Start a named gen_statem.
+%%
+%%          This function will start a gen_statem instance and register the
+%%          newly created process with the process registry.  Subsequent calls
+%%          may use the gen_statem name, in lieu of the process id.
+%%
+%%          This version of the start function will link the started gen_statem
+%%          process to the calling process.
+%%
+%%          <em><b>Note.</b>  The Options argument is currently ignored.</em>
+%% @end
+%%-----------------------------------------------------------------------------
+-spec start_link(
+    ServerName :: {local, Name :: atom()},
+    Module :: module(),
+    Args :: term(),
+    Options :: options()
+) -> {ok, pid()} | {error, Reason :: term()}.
+start_link({local, Name} = ServerName, Module, Args, Options) when is_atom(Name) ->
+    gen_server:start_link(ServerName, ?MODULE, {Module, Args}, Options).
+
+%%-----------------------------------------------------------------------------
+%% @param   Module the module in which the gen_statem callbacks are defined
+%% @param   Args the arguments to pass to the module's init callback
+%% @param   Options the options used to create the gen_statem
+%% @returns the gen_statem pid, if successful; {error, Reason}, otherwise.
+%% @doc     Start an un-named gen_statem.
+%%
+%%          This function will start a gen_statem instance.
+%%
+%%          This version of the start function will link the started gen_statem
+%%          process to the calling process.
+%%
+%%          <em><b>Note.</b>  The Options argument is currently ignored.</em>
+%% @end
+%%-----------------------------------------------------------------------------
+-spec start_link(Module :: module(), Args :: term(), Options :: options()) ->
+    {ok, pid()} | {error, Reason :: term()}.
+start_link(Module, Args, Options) ->
+    gen_server:start_link(?MODULE, {Module, Args}, Options).
+
 %%-----------------------------------------------------------------------------
 %% @equiv   stop(ServerRef, normal, infinity)
 %% @doc     Stop a previously started gen_statem.

tests/libs/estdlib/test_gen_statem.erl

@@ -34,6 +34,7 @@ test() ->
     ok = test_cast(),
     ok = test_info(),
     ok = test_timeout(),
+    ok = test_start_link(),
     ok.
 
 test_call() ->
@@ -87,6 +88,18 @@ test_timeout() ->
     gen_statem:stop(Pid),
     ok.
 
+test_start_link() ->
+    {ok, Pid} = gen_statem:start_link(?MODULE, [], []),
+
+    pong = gen_statem:call(Pid, ping),
+
+    erlang:process_flag(trap_exit, true),
+    ok = gen_statem:cast(Pid, crash),
+    receive
+        {'EXIT', Pid, _Reason} -> ok
+    after 30000 -> timeout
+    end.
+
 %%
 %% callbacks
 %%
@@ -107,7 +120,9 @@ initial({call, From}, get_num_casts, #data{num_casts = NumCasts} = Data) ->
 initial({call, From}, get_num_infos, #data{num_infos = NumInfos} = Data) ->
     {next_state, initial, Data#data{num_infos = 0}, [{reply, From, NumInfos}]};
 initial({call, From}, {go_to_jail, Ms}, Data) ->
-    {next_state, jail, Data, [{reply, From, ok}, {state_timeout, Ms, you_are_free}]}.
+    {next_state, jail, Data, [{reply, From, ok}, {state_timeout, Ms, you_are_free}]};
+initial(cast, crash, _Data) ->
+    throw(test_crash).
 
 jail({call, From}, are_you_free, Data) ->
     {next_state, jail, Data, [{reply, From, no}]};