From 000c33662b8a98870a97a3499076895d4e832563 Mon Sep 17 00:00:00 2001
From: James Fish
Date: Wed, 4 Mar 2015 23:10:25 +0000
Subject: Don't store child that returns ignore in simple supervisor
If a child of a simple_one_for_one returns ignore from its start
function no longer store the child for any restart type. It is not
possible to restart or delete the child because the supervisor is a
simple_one_for_one.
Previously a simple_one_for_one would crash, potentially without
shutting down all of its children, when it tried to shutdown a child
with undefined pid.
Previous only one undefined pid child was stored in a simple_one_for_one
supervisor no matter how many times the child start function returned
ignore.
---
lib/stdlib/doc/src/supervisor.xml | 12 +++++++++---
lib/stdlib/src/supervisor.erl | 2 +-
lib/stdlib/test/supervisor_SUITE.erl | 23 +++++++++++++++++++++++
3 files changed, 33 insertions(+), 4 deletions(-)
diff --git a/lib/stdlib/doc/src/supervisor.xml b/lib/stdlib/doc/src/supervisor.xml
index ffac1c0bd7..6ff477a42d 100644
--- a/lib/stdlib/doc/src/supervisor.xml
+++ b/lib/stdlib/doc/src/supervisor.xml
@@ -386,9 +386,15 @@
added to the supervisor and the function returns the same
value.
If the child process start function returns ignore,
- the child specification is added to the supervisor, the pid
- is set to undefined, and the function returns
- {ok,undefined}.
+ the child specification is added to the supervisor (unless the
+ supervisor is a simple_one_for_one supervisor, see below),
+ the pid is set to undefined and the function returns
+ {ok,undefined}.
+
+ In the case of a simple_one_for_one supervisor, when a child
+ process start function returns ignore the functions returns
+ {ok,undefined} and no child is added to the supervisor.
+
If the child process start function returns an error tuple or
an erroneous value, or if it fails, the child specification is
discarded, and the function returns {error,Error} where
diff --git a/lib/stdlib/src/supervisor.erl b/lib/stdlib/src/supervisor.erl
index 67655b1145..1d7396adee 100644
--- a/lib/stdlib/src/supervisor.erl
+++ b/lib/stdlib/src/supervisor.erl
@@ -381,7 +381,7 @@ handle_call({start_child, EArgs}, _From, State) when ?is_simple(State) ->
#child{mfargs = {M, F, A}} = Child,
Args = A ++ EArgs,
case do_start_child_i(M, F, Args) of
- {ok, undefined} when Child#child.restart_type =:= temporary ->
+ {ok, undefined} ->
{reply, {ok, undefined}, State};
{ok, Pid} ->
NState = save_dynamic_child(Child#child.restart_type, Pid, Args, State),
diff --git a/lib/stdlib/test/supervisor_SUITE.erl b/lib/stdlib/test/supervisor_SUITE.erl
index 9dcf19707c..015b09f35e 100644
--- a/lib/stdlib/test/supervisor_SUITE.erl
+++ b/lib/stdlib/test/supervisor_SUITE.erl
@@ -37,6 +37,7 @@
sup_start_ignore_child/1, sup_start_ignore_temporary_child/1,
sup_start_ignore_temporary_child_start_child/1,
sup_start_ignore_temporary_child_start_child_simple/1,
+ sup_start_ignore_permanent_child_start_child_simple/1,
sup_start_error_return/1, sup_start_fail/1,
sup_start_map/1, sup_start_map_faulty_specs/1,
sup_stop_infinity/1, sup_stop_timeout/1, sup_stop_brutal_kill/1,
@@ -99,6 +100,7 @@ groups() ->
sup_start_ignore_child, sup_start_ignore_temporary_child,
sup_start_ignore_temporary_child_start_child,
sup_start_ignore_temporary_child_start_child_simple,
+ sup_start_ignore_permanent_child_start_child_simple,
sup_start_error_return, sup_start_fail]},
{sup_start_map, [],
[sup_start_map, sup_start_map_faulty_specs]},
@@ -250,6 +252,27 @@ sup_start_ignore_temporary_child_start_child_simple(Config)
[1,1,0,1] = get_child_counts(sup_test).
%%-------------------------------------------------------------------------
+%% Tests what happens if child's init-callback returns ignore for a
+%% permanent child when child is started with start_child/2, and the
+%% supervisor is simple_one_for_one.
+%% Child spec shall NOT be saved!!!
+sup_start_ignore_permanent_child_start_child_simple(Config)
+ when is_list(Config) ->
+ process_flag(trap_exit, true),
+ Child1 = {child1, {supervisor_1, start_child, [ignore]},
+ permanent, 1000, worker, []},
+ {ok, Pid} = start_link({ok, {{simple_one_for_one, 2, 3600}, [Child1]}}),
+
+ {ok, undefined} = supervisor:start_child(sup_test, []),
+ {ok, CPid2} = supervisor:start_child(sup_test, []),
+
+ [{undefined, CPid2, worker, []}] = supervisor:which_children(sup_test),
+ [1,1,0,1] = get_child_counts(sup_test),
+
+ %% Regression test: check that the supervisor terminates without error.
+ exit(Pid, shutdown),
+ check_exit_reason(Pid, shutdown).
+%%-------------------------------------------------------------------------
%% Tests what happens if init-callback returns a invalid value.
sup_start_error_return(Config) when is_list(Config) ->
process_flag(trap_exit, true),
--
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