Merge branch 'nybek/speed_up_supervisor_count_children' into maint

* nybek/speed_up_supervisor_count_children:
  Speed up supervisor:count_children/1; simple_one_for_one
  Add supervisor:get_callback_module/1

OTP-13290

2 files changed, 62 insertions, 4 deletions

diff --git a/lib/stdlib/test/supervisor_SUITE.erl b/lib/stdlib/test/supervisor_SUITE.erl
index 8cb2a5194a..903ca76575 100644
--- a/lib/stdlib/test/supervisor_SUITE.erl
+++ b/lib/stdlib/test/supervisor_SUITE.erl
@@ -67,6 +67,7 @@
 
 %% Misc tests
 -export([child_unlink/1, tree/1, count_children/1,
+	 count_restarting_children/1,
 	 do_not_save_start_parameters_for_temporary_children/1,
 	 do_not_save_child_specs_for_temporary_children/1,
 	 simple_one_for_one_scale_many_temporary_children/1,
@@ -90,7 +91,8 @@ all() ->
      {group, normal_termination},
      {group, shutdown_termination},
      {group, abnormal_termination}, child_unlink, tree,
-     count_children, do_not_save_start_parameters_for_temporary_children,
+     count_children, count_restarting_children,
+     do_not_save_start_parameters_for_temporary_children,
      do_not_save_child_specs_for_temporary_children,
      simple_one_for_one_scale_many_temporary_children, temporary_bystander,
      simple_global_supervisor, hanging_restart_loop, hanging_restart_loop_simple,
@@ -1459,6 +1461,54 @@ count_children(Config) when is_list(Config) ->
     [1,0,0,0] = get_child_counts(sup_test).
 
 %%-------------------------------------------------------------------------
+%% Test count_children when some children are restarting
+count_restarting_children(Config) when is_list(Config) ->
+    process_flag(trap_exit, true),
+    Child = {child, {supervisor_deadlock, start_child_noreg, []},
+	     permanent, brutal_kill, worker, []},
+    %% 2 sek delay on failing restart (see supervisor_deadlock.erl) ->
+    %% MaxR=20, MaxT=10 should ensure a restart loop when starting and
+    %% restarting 3 instances of the child (as below)
+    {ok, SupPid} = start_link({ok, {{simple_one_for_one, 20, 10}, [Child]}}),
+
+    %% Ets table with state read by supervisor_deadlock.erl
+    ets:new(supervisor_deadlock,[set,named_table,public]),
+    ets:insert(supervisor_deadlock,{fail_start,false}),
+
+    [1,0,0,0] = get_child_counts(SupPid),
+    {ok, Ch1_1} = supervisor:start_child(SupPid, []),
+    [1,1,0,1] = get_child_counts(SupPid),
+    {ok, Ch1_2} = supervisor:start_child(SupPid, []),
+    [1,2,0,2] = get_child_counts(SupPid),
+    {ok, Ch1_3} = supervisor:start_child(SupPid, []),
+    [1,3,0,3] = get_child_counts(SupPid),
+
+    supervisor_deadlock:restart_child(Ch1_1),
+    supervisor_deadlock:restart_child(Ch1_2),
+    supervisor_deadlock:restart_child(Ch1_3),
+    test_server:sleep(400),
+    [1,3,0,3] = get_child_counts(SupPid),
+    [Ch2_1, Ch2_2, Ch2_3] = [C || {_,C,_,_} <- supervisor:which_children(SupPid)],
+
+    ets:insert(supervisor_deadlock,{fail_start,true}),
+    supervisor_deadlock:restart_child(Ch2_1),
+    supervisor_deadlock:restart_child(Ch2_2),
+    test_server:sleep(4000), % allow restart to happen before proceeding
+    [1,1,0,3] = get_child_counts(SupPid),
+
+    ets:insert(supervisor_deadlock,{fail_start,false}),
+    test_server:sleep(4000), % allow restart to happen before proceeding
+    [1,3,0,3] = get_child_counts(SupPid),
+
+    ok = supervisor:terminate_child(SupPid, Ch2_3),
+    [1,2,0,2] = get_child_counts(SupPid),
+    [Ch3_1, Ch3_2] = [C || {_,C,_,_} <- supervisor:which_children(SupPid)],
+    ok = supervisor:terminate_child(SupPid, Ch3_1),
+    [1,1,0,1] = get_child_counts(SupPid),
+    ok = supervisor:terminate_child(SupPid, Ch3_2),
+    [1,0,0,0] = get_child_counts(SupPid).
+
+%%-------------------------------------------------------------------------
 %% Temporary children shall not be restarted so they should not save
 %% start parameters, as it potentially can take up a huge amount of
 %% memory for no purpose.
diff --git a/lib/stdlib/test/supervisor_deadlock.erl b/lib/stdlib/test/supervisor_deadlock.erl
index 288547a972..8d3d1c6f30 100644
--- a/lib/stdlib/test/supervisor_deadlock.erl
+++ b/lib/stdlib/test/supervisor_deadlock.erl
@@ -11,9 +11,11 @@ init([child]) ->
             %% terminates immediately
             {ok, []};
         [{fail_start, true}] ->
-	    %% Restart frequency is MaxR=8, MaxT=10, so this will
-	    %% ensure that restart intensity is not reached -> restart
-	    %% loop
+	    %% A restart frequency of MaxR=8, MaxT=10 should ensure
+	    %% that restart intensity is not reached -> restart loop.
+	    %% (Note that if we use simple_one_for_one, and start
+	    %% 'many' child instances, the restart frequency must be
+	    %% ajusted accordingly.)
             timer:sleep(2000), % NOTE: this could be a gen_server call timeout
 
             {stop, error}
@@ -41,5 +43,11 @@ code_change(_OldVsn, State, _Extra) ->
 start_child() ->
     gen_server:start_link({local, ?MODULE}, ?MODULE, [child], []).
 
+start_child_noreg() ->
+    gen_server:start_link(?MODULE, [child], []).
+
 restart_child() ->
     gen_server:cast(supervisor_deadlock, restart).
+
+restart_child(Pid) ->
+    gen_server:cast(Pid, restart).