Merge pull request #1975 from pguyot/w46/add-sys

Add `sys` implementation for gleam/otp

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

.github/workflows/check-formatting.yaml

@@ -56,14 +56,14 @@ jobs:
 
   erlfmt-check:
     runs-on: ubuntu-24.04
-    container: erlang:27
+    container: erlang:28
     steps:
     - uses: actions/checkout@v4
 
     - name: "Check formatting with Erlang fmt"
       run: |
         cd ..
-        git clone --depth 1 -b v1.1.0 https://github.com/WhatsApp/erlfmt.git
+        git clone --depth 1 -b v1.7.0 https://github.com/WhatsApp/erlfmt.git
         cd erlfmt
         rebar3 as release escriptize
         cd ../AtomVM

CHANGELOG.md

@@ -63,6 +63,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added support for big integers in `binary_to_term/1` and `term_to_binary/1,2`
 - Added `proc_lib`
 - Added gen_server support for timeout tuples in callback return actions introduced in OTP-28.
+- Added `sys`
 
 ### Changed
 

libs/eavmlib/src/timer_manager.erl

@@ -39,14 +39,9 @@ start() ->
 
 -spec maybe_start() -> {ok, Pod :: pid()}.
 maybe_start() ->
-    case erlang:whereis(?SERVER_NAME) of
-        undefined ->
-            case start() of
-                {ok, _Pid} = R -> R;
-                {error, {already_started, Pid}} -> {ok, Pid}
-            end;
-        Pid when is_pid(Pid) ->
-            {ok, Pid}
+    case start() of
+        {ok, _Pid} = R -> R;
+        {error, {already_started, Pid}} -> {ok, Pid}
     end.
 
 %%-----------------------------------------------------------------------------

libs/estdlib/src/CMakeLists.txt

@@ -36,6 +36,7 @@ set(ERLANG_MODULES
     erts_debug
     ets
     file
+    gen
     gen_event
     gen_server
     gen_statem
@@ -58,6 +59,7 @@ set(ERLANG_MODULES
     math
     net
     proc_lib
+    sys
     file
     logger
     logger_std_h

libs/estdlib/src/gen.erl

@@ -0,0 +1,91 @@
+%
+% This file is part of AtomVM.
+%
+% Copyright 2025 Paul Guyot <[email protected]>
+%
+% 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.
+%
+% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%
+
+%%-----------------------------------------------------------------------------
+%% This module implements common code in gen_* modules, following what
+%% Erlang/OTP does with gen module. However, none of the functions exported
+%% here are public interface.
+%%-----------------------------------------------------------------------------
+
+-module(gen).
+-moduledoc false.
+
+-export([
+    call/4,
+    cast/2,
+    reply/2
+]).
+
+-type server_ref() :: atom() | pid().
+-type from() :: {pid(), reference()}.
+
+%% @private
+-spec call(ServerRef :: server_ref(), Label :: atom(), Request :: term(), Timeout :: timeout()) ->
+    Reply :: term() | {error, Reason :: term()}.
+call(ServerRef, Label, Request, Timeout) ->
+    MonitorRef = monitor(process, ServerRef),
+    ok =
+        try
+            ServerRef ! {Label, {self(), MonitorRef}, Request},
+            ok
+        catch
+            error:badarg ->
+                % Process no longer exists, monitor will send a message
+                ok
+        end,
+    receive
+        {'DOWN', MonitorRef, process, _, {E, []} = _Reason} ->
+            exit(E);
+        {'DOWN', MonitorRef, process, _, {_E, _L} = Reason} ->
+            exit(Reason);
+        {'DOWN', MonitorRef, process, _, Atom} when is_atom(Atom) ->
+            exit(Atom);
+        {MonitorRef, Reply} ->
+            demonitor(MonitorRef, [flush]),
+            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.
+        demonitor(MonitorRef, [flush]),
+        exit(timeout)
+    end.
+
+%% @private
+-spec cast(ServerRef :: server_ref(), Message :: any()) -> ok.
+cast(ServerRef, Message) ->
+    try
+        ServerRef ! {'$gen_cast', Message},
+        ok
+    catch
+        error:_ ->
+            % Process does not exist, ignore error
+            ok
+    end.
+
+%% @private
+-spec reply(From :: from(), Reply :: any()) -> ok.
+reply({Pid, Ref}, Reply) ->
+    try
+        Pid ! {Ref, Reply},
+        ok
+    catch
+        _:_ ->
+            ok
+    end.