Allow monitor options in proc_lib:start_monitor/5

Co-authored-by: Jan Uhlig <[email protected]>

Author: Maria-12648430

lib/stdlib/src/gen.erl

@@ -178,7 +178,7 @@ monitor_return({Error, Mon}) when is_reference(Mon) ->
     %% Failure; wait for spawned process to terminate
     %% and release resources, then return the error...
     receive
-        {'DOWN', Mon, process, _Pid, _Reason} ->
+        {_Tag, Mon, process, _Pid, _Reason} ->
             ok
     end,
     Error.

lib/stdlib/src/proc_lib.erl

@@ -98,15 +98,17 @@ processes that terminate as a result of this process terminating.
 %%
 -doc """
 A restricted set of [spawn options](`t:spawn_option/0`). Most notably `monitor`
-is _not_ part of these options.
+and `{monitor, MonitorOpts}` are _not_ part of these options.
 """.
 -type start_spawn_option() :: 'link'
+			    | {'link', [erlang:link_option()]}
                             | {'priority', erlang:priority_level()}
                             | {'fullsweep_after', non_neg_integer()}
                             | {'min_heap_size', non_neg_integer()}
                             | {'min_bin_vheap_size', non_neg_integer()}
                             | {'max_heap_size', erlang:max_heap_size()}
-                            | {'message_queue_data', erlang:message_queue_data() }.
+                            | {'message_queue_data', erlang:message_queue_data()}
+			    | {'async_dist', boolean()}.
 %% and this macro is used to verify that there are no monitor options
 %% which also needs to be kept in sync all kinds of monitor options
 %% in erlang:spawn_opt_options().
@@ -417,11 +419,11 @@ Argument `SpawnOpts`, if specified, is passed as the last argument to the
 
 > #### Note {: .info }
 >
-> Using spawn option `monitor` is not allowed. It causes the function to fail
-> with reason `badarg`.
+> Using spawn option `monitor` or `{monitor, Opts}` is not allowed. It causes
+> the function to fail with reason `badarg`.
 >
-> Using spawn option `link` will set a link to the spawned process, just like
-> [start_link/3,4,5](`start_link/3`).
+> Using spawn option `link` or `{link, Opts}` will set a link to the spawned
+> process, just like [start_link/3,4,5](`start_link/3`).
 """.
 -spec start(Module, Function, Args, Time, SpawnOpts) -> Ret when
       Module :: module(),
@@ -497,8 +499,11 @@ process.
 
 > #### Note {: .info }
 >
-> Using spawn option `monitor` is not allowed. It causes the function to fail
-> with reason `badarg`.
+> Using spawn option `monitor` or `{monitor, Opts}` is not allowed. It causes
+> the function to fail with reason `badarg`.
+>
+> Using spawn option `link` has no effect. The spawn option `{link, Opts}` can
+> be used to customize the link that will be set to the spawned process.
 """.
 -spec start_link(Module, Function, Args, Time, SpawnOpts) -> Ret when
       Module :: module(),
@@ -510,8 +515,9 @@ process.
 
 start_link(M,F,A,Timeout,SpawnOpts) when is_atom(M), is_atom(F), is_list(A) ->
     ?VERIFY_NO_MONITOR_OPT(M, F, A, Timeout, SpawnOpts),
+    SpawnOpts1 = ensure_spawn_option(link, SpawnOpts),
     sync_start(
-      ?MODULE:spawn_opt(M, F, A, [link,monitor|SpawnOpts]), Timeout).
+      ?MODULE:spawn_opt(M, F, A, [monitor | SpawnOpts1]), Timeout).
 
 
 -doc(#{equiv => start_monitor(Module, Function, Args, infinity)}).
@@ -556,28 +562,28 @@ when this function times out and kills the spawned process.
 
 > #### Note {: .info }
 >
-> Using spawn option `monitor` is not allowed. It causes the function to fail
-> with reason `badarg`.
+> Using spawn option `monitor` has no effect. The spawn option `{monitor, Opts}`
+> can be used to customize the monitor that will be set on the spawned process. 
 >
-> Using spawn option `link` will set a link to the spawned process, just like
-> [start_link/3,4,5](`start_link/3`).
+> Using spawn option `link` or `{link, Opts}` will set a link to the spawned
+> process, just like [start_link/3,4,5](`start_link/3`).
 """.
 -doc(#{since => <<"OTP 23.0">>}).
 -spec start_monitor(Module, Function, Args, Time, SpawnOpts) -> {Ret, Mon} when
       Module :: module(),
       Function :: atom(),
       Args :: [term()],
       Time :: timeout(),
-      SpawnOpts :: [start_spawn_option()],
+      SpawnOpts :: [spawn_option()],
       Mon :: reference(),
       Ret :: term() | {error, Reason :: term()}.
 
 start_monitor(M,F,A,Timeout,SpawnOpts) when is_atom(M),
                                             is_atom(F),
                                             is_list(A) ->
-    ?VERIFY_NO_MONITOR_OPT(M, F, A, Timeout, SpawnOpts),
+    SpawnOpts1 = ensure_spawn_option(monitor, SpawnOpts),
     sync_start_monitor(
-      ?MODULE:spawn_opt(M, F, A, [monitor|SpawnOpts]), Timeout).
+      ?MODULE:spawn_opt(M, F, A, SpawnOpts1), Timeout).
 
 sync_start_monitor({Pid, Ref}, Timeout) ->
     receive
@@ -587,7 +593,7 @@ sync_start_monitor({Pid, Ref}, Timeout) ->
             flush_EXIT(Pid),
             self() ! await_DOWN(Pid, Ref),
             {Return, Ref};
-	{'DOWN', Ref, process, Pid, Reason} = Down ->
+	{_, Ref, process, Pid, Reason} = Down ->
             flush_EXIT(Pid),
             self() ! Down,
             {{error, Reason}, Ref}
@@ -597,6 +603,19 @@ sync_start_monitor({Pid, Ref}, Timeout) ->
             {{error, timeout}, Ref}
     end.
 
+%% Adds the given Opt atom to the given SpawnOpts list
+%% if it is not already contained either in plain form
+%% or as the first element of a tuple.
+ensure_spawn_option(Opt, [Opt | _] = SpawnOpts) ->
+    SpawnOpts;
+ensure_spawn_option(Opt, [SpawnOpt | _] = SpawnOpts)
+  when Opt =:= element(1, SpawnOpt) ->
+    SpawnOpts;
+ensure_spawn_option(Opt, [SpawnOpt | SpawnOpts]) ->
+    [SpawnOpt | ensure_spawn_option(Opt, SpawnOpts)];
+ensure_spawn_option(Opt, []) ->
+    [Opt].
+
 
 %% We regard the existence of an {'EXIT', Pid, _} message
 %% as proof enough that there was a link that fired and
@@ -620,7 +639,7 @@ kill_flush_EXIT(Pid) ->
 
 await_DOWN(Pid, Ref) ->
     receive
-	{'DOWN', Ref, process, Pid, _} = Down ->
+	{_, Ref, process, Pid, _} = Down ->
             Down
     end.
 

lib/stdlib/test/proc_lib_SUITE.erl

@@ -29,11 +29,11 @@
 -export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
 	 init_per_group/2,end_per_group/2, 
 	 crash/1, stacktrace/1, sync_start_nolink/1, sync_start_link/1,
-         sync_start_monitor/1, sync_start_monitor_link/1,
+         sync_start_monitor/1, sync_start_monitor_link/1, sync_start_monitor_monitor/1,
          sync_start_timeout/1, sync_start_link_timeout/1,
          sync_start_monitor_link_timeout/1,
          spawn_opt/1, sp1/0, sp1_with_label/0, sp2/0, sp3/1, sp4/2,
-         sp5/1, sp6/1, sp7/1, sp8/1, sp9/1, sp10/1,
+         sp5/1, sp6/1, sp7_link/1, sp7_monitor/1, sp8/1, sp9/1, sp10/1,
          '\x{447}'/0, hibernate/1, stop/1, t_format/1, t_format_arbitrary/1]).
 -export([ otp_6345/1, init_dont_hang/1]).
 
@@ -64,7 +64,7 @@ all() ->
 groups() -> 
     [{tickets, [], [otp_6345, init_dont_hang]},
      {sync_start, [], [sync_start_nolink, sync_start_link,
-                       sync_start_monitor, sync_start_monitor_link,
+                       sync_start_monitor, sync_start_monitor_link, sync_start_monitor_monitor,
                        sync_start_timeout, sync_start_link_timeout,
                        sync_start_monitor_link_timeout]}].
 
@@ -313,7 +313,7 @@ sync_start_monitor(Config) when is_list(Config) ->
     ok.
 
 sync_start_monitor_link(Config) when is_list(Config) ->
-    _Pid = spawn_link(?MODULE, sp7, [self()]),
+    _Pid = spawn_link(?MODULE, sp7_link, [self()]),
     receive
 	{sync_started, _} -> ct:fail(async_start)
     after 1000 -> ok
@@ -334,6 +334,26 @@ sync_start_monitor_link(Config) when is_list(Config) ->
     end,
     ok.
 
+sync_start_monitor_monitor(Config) when is_list(Config) ->
+    _Pid = spawn_link(?MODULE, sp7_monitor, [self()]),
+    receive
+	{sync_started, _} -> ct:fail(async_start)
+    after 1000 -> ok
+    end,
+    receive
+	{Pid2, init} ->
+	    Pid2 ! go_on
+    end,
+    receive
+	{sync_started, _} -> ok
+    after 1000 -> ct:fail(no_sync_start)
+    end,
+    receive received_down -> ok
+    after 1000 -> ct:fail(no_down)
+    end,
+    ok.
+
+
 sync_start_timeout(Config) when is_list(Config) ->
     _Pid = spawn_link(?MODULE, sp8, [self()]),
     receive done -> ok end,
@@ -445,7 +465,7 @@ sp6(Tester) ->
             Tester ! received_down
     end.
 
-sp7(Tester) ->
+sp7_link(Tester) ->
     process_flag(trap_exit, true),
     {Pid, Mon} = proc_lib:start_monitor(?MODULE, sp4, [self(), Tester], infinity, [link]),
     Tester ! {sync_started, Pid},
@@ -458,6 +478,15 @@ sp7(Tester) ->
             Tester ! received_down
     end.
 
+sp7_monitor(Tester) ->
+    process_flag(trap_exit, true),
+    {Pid, Mon} = proc_lib:start_monitor(?MODULE, sp4, [self(), Tester], infinity, [{monitor, [{tag, sp7_monitor}]}]),
+    Tester ! {sync_started, Pid},
+    receive
+        {sp7_monitor, Mon, process, Pid, normal} ->
+            Tester ! received_down
+    end.
+
 sp8(Tester) ->
     process_flag(trap_exit, true),
     {error,timeout} = proc_lib:start(?MODULE, sp4, [self(), Tester], 500, [link]),
@@ -622,8 +651,12 @@ hib_receive_messages(N) ->
 otp_6345(Config) when is_list(Config) ->
     Opts = [link,monitor],
     try
-        blupp = proc_lib:start(?MODULE, otp_6345_init, [self()],
-                               1000, Opts)
+        proc_lib:start(?MODULE, otp_6345_init, [self()],
+                       1000, Opts)
+    of
+	{ok, Pid} ->
+	    exit(Pid, kill),
+	    ct:fail(monitor_option_accepted)
     catch
         error:badarg -> ok
     end.