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# vim: ts=2 sw=2 expandtab
# Test a case that Yuval Kogman ran into. Decrementing a reference
# count would immediately trigger a GC test. During _start, that
# means a session might be GC'd before _start's handler returned.
# Fatal hilarity would ensue.
use warnings;
use strict;
use Test::More tests => 5;
sub POE::Kernel::ASSERT_DEFAULT () { 1 }
sub POE::Kernel::TRACE_DEFAULT () { 0 }
use POE;
my $sigidle = 0;
# The "bystander" session is kept alive solely by its extra reference
# count. It should be stopped when the "refcount" session destructs.
# This is determined by comparing the _stop time vs. SIGIDLE delivery.
# If _stop is first, then the bystander was reaped correctly.
my $bystander_id = POE::Session->create(
inline_states => {
_start => sub {
$_[KERNEL]->refcount_increment( $_[SESSION]->ID, "just hold me");
},
_stop => sub {
ok(
!$sigidle,
"bystander stopped before sigidle"
);
},
},
)->ID;
# The "sigidle" session watches for SIGIDLE and sets a flag. If the
# bystander is reaped after SIGIDLE, it means that the refcount
# session did not trigger its destruction.
POE::Session->create(
inline_states => {
_start => sub {
$_[KERNEL]->sig( IDLE => 'got_sigidle' );
$_[KERNEL]->alias_set("stayin_alive");
},
got_sigidle => sub {
$sigidle++;
pass("got sigidle");
},
_stop => sub {
pass("sigidle session is allowed to stop");
},
},
);
# The "refcount" session attempts to trigger its own untimely
# destruction by incrementing and decrementing a reference count. If
# it succeeds in killing itself off early, then its "do_something"
# event will cause a fatal runtime error when ASSERT_DEFAULT is on.
#
# As part of _stop, it decrements the extra reference on the bystander
# session, triggering its destruction before SIGIDLE. If there's a
# problem, SIGIDLE will arrive first---because POE::Kernel has a
# refcount of 0 but the session still exists.
POE::Session->create(
inline_states => {
_start => sub {
$_[KERNEL]->refcount_increment($_[SESSION]->ID, "just hold me");
$_[KERNEL]->refcount_decrement($_[SESSION]->ID, "just hold me");
$_[KERNEL]->yield("do_something");
},
do_something => sub {
pass("refcount session is allowed to run");
},
_stop => sub {
pass("refcount session is allowed to stop");
$_[KERNEL]->refcount_decrement($bystander_id, "just hold me");
},
},
);
POE::Kernel->run();
1;
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