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 $CGI::SpeedyCGI::i_am_speedy;
42 my ($in_global_destruction, $before_is_installed);
44 sub in_global_destruction () { $in_global_destruction }
46 # This block will fire towards the end of the program execution
47 # Since there is no way for us to generate an END which will execute *last*
48 # this is *NOT 100% INCOMPATIBLE* with XS/${^GLOBAL_PHASE}. We *may* end up
49 # with a true in_gloal_destruction() in the middle of another END block
50 # There are no practical cases where this matters.
53 $in_global_destruction = 1;
56 # threads do not execute the global ENDs (it would be stupid). However
57 # one can register a new END via simple string eval within a thread, and
58 # achieve the same result. A logical place to do this would be CLONE, which
59 # is claimed to run in the context of the new thread. However this does
60 # not really seem to be the case - any END evaled in a CLONE is ignored :(
61 # Hence blatantly hooking threads::create
63 if ($INC{'threads.pm'}) {
64 my $orig_create = threads->can('create');
65 no warnings 'redefine';
66 *threads::create = sub {
67 { local $@; eval 'END { $in_global_destruction = 1 }' };
70 $before_is_installed = 1;
73 # just in case threads got loaded after us (silly)
75 unless ($before_is_installed) {
77 Carp::croak("You must load the 'threads' module before @{[ __PACKAGE__ ]}");
87 1; # keep require happy
94 Devel::GlobalDestruction - Expose the flag which marks global
100 use Devel::GlobalDestruction;
102 use namespace::clean; # to avoid having an "in_global_destruction" method
105 return if in_global_destruction;
107 do_something_a_little_tricky();
112 Perl's global destruction is a little tricky to deal with WRT finalizers
113 because it's not ordered and objects can sometimes disappear.
115 Writing defensive destructors is hard and annoying, and usually if global
116 destruction is happenning you only need the destructors that free up non
117 process local resources to actually execute.
119 For these constructors you can avoid the mess by simply bailing out if global
120 destruction is in effect.
124 This module uses L<Sub::Exporter::Progressive> so the exports may be renamed,
125 aliased, etc. if L<Sub::Exporter> is present.
129 =item in_global_destruction
131 Returns true if the interpreter is in global destruction. In perl 5.14+, this
132 returns C<${^GLOBAL_PHASE} eq 'DESTRUCT'>, and on earlier perls, it returns the
133 current value of C<PL_dirty>.
139 Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt>
141 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
143 Jesse Luehrs E<lt>doy@tozt.netE<gt>
145 Peter Rabbitson E<lt>ribasushi@cpan.orgE<gt>
147 Arthur Axel 'fREW' Schmidt E<lt>frioux@gmail.comE<gt>
151 Copyright (c) 2008 Yuval Kogman. All rights reserved
152 This program is free software; you can redistribute
153 it and/or modify it under the same terms as Perl itself.