Commit | Line | Data |
a91e8a78 |
1 | package Devel::GlobalDestruction; |
2 | |
3 | use strict; |
4 | use warnings; |
5 | |
1c89491d |
6 | our $VERSION = '0.08'; |
a91e8a78 |
7 | |
aaccce0c |
8 | use Sub::Exporter::Progressive -setup => { |
f832e240 |
9 | exports => [ qw(in_global_destruction) ], |
10 | groups => { default => [ -all ] }, |
a91e8a78 |
11 | }; |
12 | |
6e3fd33e |
13 | # we run 5.14+ - everything is in core |
14 | # |
eaac10b5 |
15 | if (defined ${^GLOBAL_PHASE}) { |
3790e928 |
16 | eval 'sub in_global_destruction () { ${^GLOBAL_PHASE} eq q[DESTRUCT] }'; |
17 | } |
6e3fd33e |
18 | # try to load the xs version if it was compiled |
19 | # |
9aaf3646 |
20 | elsif (eval { |
21 | require XSLoader; |
3790e928 |
22 | XSLoader::load(__PACKAGE__, $VERSION); |
9aaf3646 |
23 | 1; |
24 | }) { |
25 | # the eval already installed everything, nothing to do |
3790e928 |
26 | } |
6e3fd33e |
27 | # Not core nor XS |
28 | # |
9aaf3646 |
29 | else { |
9d5ad143 |
30 | |
31 | # SpeedyCGI runs END blocks every cycle but somehow keeps object instances |
32 | # hence DIAF |
33 | die("The pure-perl version of @{[__PACKAGE__]} can not function correctly under CGI::SpeedyCGI. " |
34 | . "Please ensure you have a working compiler, and reinstall @{[__PACKAGE__]} to enable the XS " |
35 | . "codepath.\n" |
36 | ) if $CGI::SpeedyCGI::i_am_speedy; |
37 | |
9aaf3646 |
38 | eval <<'PP_IGD' or die $@; |
3790e928 |
39 | |
9aaf3646 |
40 | my ($in_global_destruction, $before_is_installed); |
a91e8a78 |
41 | |
41ec1eaf |
42 | sub in_global_destruction () { $in_global_destruction } |
9aaf3646 |
43 | |
6e3fd33e |
44 | # This block will fire towards the end of the program execution |
45 | # Since there is no way for us to generate an END which will execute *last* |
46 | # this is *NOT 100% INCOMPATIBLE* with XS/${^GLOBAL_PHASE}. We *may* end up |
47 | # with a true in_gloal_destruction() in the middle of another END block |
48 | # There are no practical cases where this matters. |
49 | # |
9aaf3646 |
50 | END { |
9d5ad143 |
51 | $in_global_destruction = 1; |
9aaf3646 |
52 | } |
53 | |
54 | # threads do not execute the global ENDs (it would be stupid). However |
55 | # one can register a new END via simple string eval within a thread, and |
56 | # achieve the same result. A logical place to do this would be CLONE, which |
57 | # is claimed to run in the context of the new thread. However this does |
58 | # not really seem to be the case - any END evaled in a CLONE is ignored :( |
59 | # Hence blatantly hooking threads::create |
6e3fd33e |
60 | # |
9aaf3646 |
61 | if ($INC{'threads.pm'}) { |
62 | my $orig_create = threads->can('create'); |
63 | no warnings 'redefine'; |
64 | *threads::create = sub { |
65 | { local $@; eval 'END { $in_global_destruction = 1 }' }; |
66 | goto $orig_create; |
67 | }; |
68 | $before_is_installed = 1; |
69 | } |
70 | |
71 | # just in case threads got loaded after us (silly) |
72 | sub CLONE { |
73 | unless ($before_is_installed) { |
74 | require Carp; |
75 | Carp::croak("You must load the 'threads' module before @{[ __PACKAGE__ ]}"); |
76 | } |
77 | } |
a91e8a78 |
78 | |
9aaf3646 |
79 | 1; # keep eval happy |
80 | |
81 | PP_IGD |
82 | |
83 | } |
84 | |
85 | 1; # keep require happy |
86 | |
87 | |
88 | __END__ |
a91e8a78 |
89 | |
90 | =head1 NAME |
91 | |
761f3ee2 |
92 | Devel::GlobalDestruction - Expose the flag which marks global |
a91e8a78 |
93 | destruction. |
94 | |
95 | =head1 SYNOPSIS |
96 | |
f832e240 |
97 | package Foo; |
98 | use Devel::GlobalDestruction; |
a91e8a78 |
99 | |
f832e240 |
100 | use namespace::clean; # to avoid having an "in_global_destruction" method |
a91e8a78 |
101 | |
f832e240 |
102 | sub DESTROY { |
103 | return if in_global_destruction; |
a91e8a78 |
104 | |
f832e240 |
105 | do_something_a_little_tricky(); |
106 | } |
a91e8a78 |
107 | |
108 | =head1 DESCRIPTION |
109 | |
110 | Perl's global destruction is a little tricky to deal with WRT finalizers |
111 | because it's not ordered and objects can sometimes disappear. |
112 | |
113 | Writing defensive destructors is hard and annoying, and usually if global |
114 | destruction is happenning you only need the destructors that free up non |
115 | process local resources to actually execute. |
116 | |
117 | For these constructors you can avoid the mess by simply bailing out if global |
118 | destruction is in effect. |
119 | |
120 | =head1 EXPORTS |
121 | |
aaccce0c |
122 | This module uses L<Sub::Exporter::Progressive> so the exports may be renamed, |
123 | aliased, etc. if L<Sub::Exporter> is present. |
a91e8a78 |
124 | |
125 | =over 4 |
126 | |
127 | =item in_global_destruction |
128 | |
761f3ee2 |
129 | Returns true if the interpreter is in global destruction. In perl 5.14+, this |
130 | returns C<${^GLOBAL_PHASE} eq 'DESTRUCT'>, and on earlier perls, it returns the |
131 | current value of C<PL_dirty>. |
a91e8a78 |
132 | |
133 | =back |
134 | |
ec94b9e1 |
135 | =head1 AUTHORS |
a91e8a78 |
136 | |
137 | Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt> |
138 | |
ec94b9e1 |
139 | Florian Ragwitz E<lt>rafl@debian.orgE<gt> |
140 | |
aaa7f60f |
141 | Jesse Luehrs E<lt>doy@tozt.netE<gt> |
142 | |
9aaf3646 |
143 | Peter Rabbitson E<lt>ribasushi@cpan.orgE<gt> |
144 | |
aaccce0c |
145 | Arthur Axel 'fREW' Schmidt E<lt>frioux@gmail.comE<gt> |
146 | |
a91e8a78 |
147 | =head1 COPYRIGHT |
148 | |
f832e240 |
149 | Copyright (c) 2008 Yuval Kogman. All rights reserved |
150 | This program is free software; you can redistribute |
151 | it and/or modify it under the same terms as Perl itself. |
a91e8a78 |
152 | |
153 | =cut |