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] }';
18 # try to load the xs version if it was compiled
22 XSLoader::load(__PACKAGE__, $VERSION);
25 # the eval already installed everything, nothing to do
28 # The whole thing is in an eval to prevent perl from parsing it in the
29 # first place under perls where none of this is needed
32 eval <<'PP_IGD' or die $@;
34 # SpeedyCGI runs END blocks every cycle but somehow keeps object instances
36 die("The pure-perl version of @{[__PACKAGE__]} can not function correctly under CGI::SpeedyCGI. "
37 . "Please ensure you have a working compiler, and reinstall @{[__PACKAGE__]} to enable the XS "
39 ) if $CGI::SpeedyCGI::i_am_speedy;
41 my ($in_global_destruction, $before_is_installed);
43 sub in_global_destruction () { $in_global_destruction }
45 # end_av trick suggested by liz++
47 my $add_endblock = sub {
48 push @{ B::end_av()->object_2svref }, sub { $in_global_destruction = 1 };
51 # This block will fire towards the end of the program execution
52 # Use it to inject an END block which is guaranteed to run last
53 # (as long as something else doesn't inject yet another block in
54 # the same manner afterwards, at which point it hardly matters
57 END { $add_endblock->() }
59 # threads do not execute the global ENDs (it would be stupid). However
60 # one can register a new END via simple string eval within a thread, and
61 # achieve the same result. A logical place to do this would be CLONE, which
62 # is claimed to run in the context of the new thread. However this does
63 # not really seem to be the case - any END evaled in a CLONE is ignored :(
64 # Hence blatantly hooking threads::create
66 if ($INC{'threads.pm'}) {
67 my $orig_create = threads->can('create');
68 no warnings 'redefine';
69 *threads::create = sub {
70 { local $@; eval 'END { $in_global_destruction = 1 }' };
73 $before_is_installed = 1;
76 # just in case threads got loaded after us (silly)
78 unless ($before_is_installed) {
80 Carp::croak("You must load the 'threads' module before @{[ __PACKAGE__ ]}");
90 1; # keep require happy
97 Devel::GlobalDestruction - Expose the flag which marks global
103 use Devel::GlobalDestruction;
105 use namespace::clean; # to avoid having an "in_global_destruction" method
108 return if in_global_destruction;
110 do_something_a_little_tricky();
115 Perl's global destruction is a little tricky to deal with WRT finalizers
116 because it's not ordered and objects can sometimes disappear.
118 Writing defensive destructors is hard and annoying, and usually if global
119 destruction is happenning you only need the destructors that free up non
120 process local resources to actually execute.
122 For these constructors you can avoid the mess by simply bailing out if global
123 destruction is in effect.
127 This module uses L<Sub::Exporter::Progressive> so the exports may be renamed,
128 aliased, etc. if L<Sub::Exporter> is present.
132 =item in_global_destruction
134 Returns true if the interpreter is in global destruction. In perl 5.14+, this
135 returns C<${^GLOBAL_PHASE} eq 'DESTRUCT'>, and on earlier perls, it returns the
136 current value of C<PL_dirty>.
142 Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt>
144 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
146 Jesse Luehrs E<lt>doy@tozt.netE<gt>
148 Peter Rabbitson E<lt>ribasushi@cpan.orgE<gt>
150 Arthur Axel 'fREW' Schmidt E<lt>frioux@gmail.comE<gt>
152 Elizabeth Mattijsen E<lt>liz@dijkmat.nlE<gt>
156 Copyright (c) 2008 Yuval Kogman. All rights reserved
157 This program is free software; you can redistribute
158 it and/or modify it under the same terms as Perl itself.