1 package Devel::GlobalDestruction;
8 use Sub::Exporter::Progressive -setup => {
9 exports => [ qw(in_global_destruction) ],
10 groups => { default => [ -all ] },
13 # we run 5.14+ - everything is in core
15 if (defined ${^GLOBAL_PHASE}) {
16 eval 'sub in_global_destruction () { ${^GLOBAL_PHASE} eq q[DESTRUCT] }; 1'
19 # try to load the xs version if it was compiled
23 XSLoader::load(__PACKAGE__, $VERSION);
26 # the eval already installed everything, nothing to do
29 # The whole thing is in an eval to prevent perl from parsing it in the
30 # first place under perls where none of this is needed
33 eval <<'PP_IGD' or die $@;
35 # SpeedyCGI runs END blocks every cycle but somehow keeps object instances
37 die("The pure-perl version of @{[__PACKAGE__]} can not function correctly under CGI::SpeedyCGI. "
38 . "Please ensure you have a working compiler, and reinstall @{[__PACKAGE__]} to enable the XS "
40 ) if $CGI::SpeedyCGI::i_am_speedy;
42 my ($in_global_destruction, $before_is_installed);
44 sub in_global_destruction () { $in_global_destruction }
46 # end_av trick suggested by liz++
48 my $add_endblock = sub {
49 push @{ B::end_av()->object_2svref }, sub { $in_global_destruction = 1 };
52 # This block will fire towards the end of the program execution
53 # Use it to inject an END block which is guaranteed to run last
54 # (as long as something else doesn't inject yet another block in
55 # the same manner afterwards, at which point it hardly matters
58 END { $add_endblock->() }
60 # threads do not execute the global ENDs (it would be stupid). However
61 # one can register a new thread-local END from within a thread, and
62 # achieve the same result. A logical place to do this would be CLONE, which
63 # is claimed to run in the context of the new thread. However this does
64 # not really seem to be the case - any END inserted in a CLONE is ignored :(
65 # Hence blatantly hooking threads::create
67 if ($INC{'threads.pm'}) {
70 my $orig_create = threads->can('create');
71 no warnings 'redefine';
73 *threads::create = sub {
77 unless ( (Scalar::Util::reftype($target)||'') eq 'CODE' ) {
79 $target = \&{ caller() . "::$target" };
85 # Perls compiled with THREADS_HAVE_PIDS do not copy end_av properly
86 # between threads, so B::end_av ends up returning a B::SPECIAL and it
87 # goes downhill from there
88 # Install a noop END just to be on the safe side
89 { local $@; eval 'END {}' }
99 $before_is_installed = 1;
102 # just in case threads got loaded after us (silly)
104 unless ($before_is_installed) {
106 Carp::croak("You must load the 'threads' module before @{[ __PACKAGE__ ]}");
116 1; # keep require happy
123 Devel::GlobalDestruction - Expose the flag which marks global
129 use Devel::GlobalDestruction;
131 use namespace::clean; # to avoid having an "in_global_destruction" method
134 return if in_global_destruction;
136 do_something_a_little_tricky();
141 Perl's global destruction is a little tricky to deal with WRT finalizers
142 because it's not ordered and objects can sometimes disappear.
144 Writing defensive destructors is hard and annoying, and usually if global
145 destruction is happenning you only need the destructors that free up non
146 process local resources to actually execute.
148 For these constructors you can avoid the mess by simply bailing out if global
149 destruction is in effect.
153 This module uses L<Sub::Exporter::Progressive> so the exports may be renamed,
154 aliased, etc. if L<Sub::Exporter> is present.
158 =item in_global_destruction
160 Returns true if the interpreter is in global destruction. In perl 5.14+, this
161 returns C<${^GLOBAL_PHASE} eq 'DESTRUCT'>, and on earlier perls, it returns the
162 current value of C<PL_dirty>.
168 Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt>
170 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
172 Jesse Luehrs E<lt>doy@tozt.netE<gt>
174 Peter Rabbitson E<lt>ribasushi@cpan.orgE<gt>
176 Arthur Axel 'fREW' Schmidt E<lt>frioux@gmail.comE<gt>
178 Elizabeth Mattijsen E<lt>liz@dijkmat.nlE<gt>
182 Copyright (c) 2008 Yuval Kogman. All rights reserved
183 This program is free software; you can redistribute
184 it and/or modify it under the same terms as Perl itself.