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Allow monitor options in proc_lib:start_monitor/5 #9804

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2 changes: 1 addition & 1 deletion lib/stdlib/src/gen.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand Down
55 changes: 37 additions & 18 deletions lib/stdlib/src/proc_lib.erl
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Expand Up @@ -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().
Expand Down Expand Up @@ -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(),
Expand Down Expand Up @@ -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(),
Expand All @@ -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)}).
Expand Down Expand Up @@ -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
Expand All @@ -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}
Expand All @@ -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
Expand All @@ -620,7 +639,7 @@ kill_flush_EXIT(Pid) ->

await_DOWN(Pid, Ref) ->
receive
{'DOWN', Ref, process, Pid, _} = Down ->
{_, Ref, process, Pid, _} = Down ->
Down
end.

Expand Down
47 changes: 40 additions & 7 deletions lib/stdlib/test/proc_lib_SUITE.erl
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Expand Up @@ -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]).

Expand Down Expand Up @@ -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]}].

Expand Down Expand Up @@ -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
Expand All @@ -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,
Expand Down Expand Up @@ -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},
Expand All @@ -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]),
Expand Down Expand Up @@ -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.
Expand Down
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