Merge pull request #1980 from pguyot/w46/fix-gen-api

Change `gen:call/4` signature to match OTP's

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.erl

@@ -36,9 +36,18 @@
 -type server_ref() :: atom() | pid().
 -type from() :: {pid(), reference()}.
 
-%% @private
+%%-----------------------------------------------------------------------------
+%% @doc     Perform a call on a gen server. This API not documented by OTP,
+%% yet Elixir uses it, so this function matches the current OTP-28 behavior.
+%% @end
+%% @param ServerRef the server to call
+%% @param Label the label for the message, typically `system' or `$gen_call'
+%% @param Request the message to send
+%% @param Timeout timeout for sending the message
+%% @returns `{ok, Result}' or raises an exit exception
+%%-----------------------------------------------------------------------------
 -spec call(ServerRef :: server_ref(), Label :: atom(), Request :: term(), Timeout :: timeout()) ->
-    Reply :: term() | {error, Reason :: term()}.
+    {ok, Reply :: term()} | {error, Reason :: term()}.
 call(ServerRef, Label, Request, Timeout) ->
     MonitorRef = monitor(process, ServerRef),
     ok =
@@ -59,7 +68,7 @@ call(ServerRef, Label, Request, Timeout) ->
             exit(Atom);
         {MonitorRef, Reply} ->
             demonitor(MonitorRef, [flush]),
-            Reply
+            {ok, Reply}
     after Timeout ->
         % If Timeout is small enough (0), the error message might be timeout
         % instead of noproc as there could be a race condition with the monitor.

libs/estdlib/src/gen_server.erl

@@ -422,8 +422,8 @@ call(ServerRef, Request) ->
 -spec call(ServerRef :: server_ref(), Request :: term(), TimeoutMs :: timeout()) ->
     Reply :: term() | {error, Reason :: term()}.
 call(ServerRef, Request, TimeoutMs) ->
-    try
-        gen:call(ServerRef, '$gen_call', Request, TimeoutMs)
+    try gen:call(ServerRef, '$gen_call', Request, TimeoutMs) of
+        {ok, Result} -> Result
     catch
         exit:Reason ->
             exit({Reason, {?MODULE, ?FUNCTION_NAME, [ServerRef, Request, TimeoutMs]}})

libs/estdlib/src/gen_statem.erl

@@ -210,8 +210,8 @@ call(ServerRef, Request) ->
 -spec call(ServerRef :: server_ref(), Request :: term(), Timeout :: timeout()) ->
     Reply :: term() | {error, Reason :: term()}.
 call(ServerRef, Request, Timeout) ->
-    try
-        gen:call(ServerRef, '$gen_call', Request, Timeout)
+    try gen:call(ServerRef, '$gen_call', Request, Timeout) of
+        {ok, Reply} -> Reply
     catch
         exit:Reason ->
             exit({Reason, {?MODULE, ?FUNCTION_NAME, [ServerRef, Request]}})

libs/estdlib/src/sys.erl

@@ -130,7 +130,8 @@ change_code(Name, Module, OldVsn, Extra) ->
     Timeout :: timeout()
 ) -> ok | {error, any()}.
 change_code(Name, Module, OldVsn, Extra, Timeout) ->
-    gen:call(Name, system, {change_code, Module, OldVsn, Extra}, Timeout).
+    {ok, Reply} = gen:call(Name, system, {change_code, Module, OldVsn, Extra}, Timeout),
+    Reply.
 
 %% @equiv get_state(Name, 5000)
 -spec get_state(Name :: name()) -> any().
@@ -147,7 +148,8 @@ get_state(Name) ->
 %%-----------------------------------------------------------------------------
 -spec get_state(Name :: name(), timeout()) -> any().
 get_state(Name, Timeout) ->
-    case gen:call(Name, system, get_state, Timeout) of
+    {ok, Reply} = gen:call(Name, system, get_state, Timeout),
+    case Reply of
         {ok, State} -> State;
         {error, Reason} -> error(Reason)
     end.
@@ -168,7 +170,8 @@ get_status(Name) ->
 -spec get_status(Name :: name(), Timeout :: timeout()) ->
     {status, pid(), {module, module()}, [SItem :: any()]}.
 get_status(Name, Timeout) ->
-    gen:call(Name, system, get_status, Timeout).
+    {ok, Reply} = gen:call(Name, system, get_status, Timeout),
+    Reply.
 
 %% @equiv replace_state(Name, StateFun, 5000)
 -spec replace_state(Name :: name(), StateFun :: fun((any()) -> any())) -> ok.
@@ -185,7 +188,8 @@ replace_state(Name, StateFun) ->
 %%-----------------------------------------------------------------------------
 -spec replace_state(Name :: name(), StateFun :: fun((any()) -> any()), Timeout :: timeout()) -> ok.
 replace_state(Name, StateFun, Timeout) ->
-    case gen:call(Name, system, {replace_state, StateFun}, Timeout) of
+    {ok, Reply} = gen:call(Name, system, {replace_state, StateFun}, Timeout),
+    case Reply of
         {ok, State} -> State;
         {error, Reason} -> error(Reason)
     end.
@@ -204,7 +208,8 @@ resume(Name) ->
 %%-----------------------------------------------------------------------------
 -spec resume(Name :: name(), Timeout :: timeout()) -> ok.
 resume(Name, Timeout) ->
-    gen:call(Name, system, resume, Timeout).
+    {ok, ok} = gen:call(Name, system, resume, Timeout),
+    ok.
 
 %% @equiv suspend(Name, 5000)
 -spec suspend(Name :: name()) -> ok.
@@ -221,7 +226,8 @@ suspend(Name) ->
 %%-----------------------------------------------------------------------------
 -spec suspend(Name :: name(), Timeout :: timeout()) -> ok.
 suspend(Name, Timeout) ->
-    gen:call(Name, system, suspend, Timeout).
+    {ok, ok} = gen:call(Name, system, suspend, Timeout),
+    ok.
 
 %% @equiv terminate(Name, Reason, 5000)
 -spec terminate(Name :: name(), Reason :: any()) -> ok.
@@ -238,7 +244,8 @@ terminate(Name, Reason) ->
 %%-----------------------------------------------------------------------------
 -spec terminate(Name :: name(), Reason :: any(), Timeout :: timeout()) -> ok.
 terminate(Name, Reason, Timeout) ->
-    gen:call(Name, system, {terminate, Reason}, Timeout).
+    {ok, ok} = gen:call(Name, system, {terminate, Reason}, Timeout),
+    ok.
 
 %% @equiv trace(Name, Flag, 5000)
 -spec trace(Name :: name(), Flag :: boolean()) -> ok.
@@ -255,7 +262,8 @@ trace(Name, Flag) ->
 %%-----------------------------------------------------------------------------
 -spec trace(Name :: name(), Flag :: boolean(), Timeout :: timeout()) -> ok.
 trace(Name, Flag, Timeout) ->
-    gen:call(Name, system, {debug, {trace, Flag}}, Timeout).
+    {ok, ok} = gen:call(Name, system, {debug, {trace, Flag}}, Timeout),
+    ok.
 
 %%-----------------------------------------------------------------------------
 %% Process Implementation Functions