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1 | package Devel::GlobalDestruction; |
2 | |
3 | use strict; |
4 | use warnings; |
5 | |
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6 | our $VERSION = '0.08'; |
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7 | |
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8 | use Sub::Exporter::Progressive -setup => { |
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9 | exports => [ qw(in_global_destruction) ], |
10 | groups => { default => [ -all ] }, |
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11 | }; |
12 | |
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13 | # we run 5.14+ - everything is in core |
14 | # |
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15 | if (defined ${^GLOBAL_PHASE}) { |
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16 | eval 'sub in_global_destruction () { ${^GLOBAL_PHASE} eq q[DESTRUCT] }'; |
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17 | } |
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18 | # try to load the xs version if it was compiled |
19 | # |
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20 | elsif (eval { |
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21 | require XSLoader; |
22 | XSLoader::load(__PACKAGE__, $VERSION); |
23 | 1; |
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24 | }) { |
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25 | # the eval already installed everything, nothing to do |
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26 | } |
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27 | # Not core nor XS |
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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 |
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30 | # |
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31 | else { |
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32 | eval <<'PP_IGD' or die $@; |
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33 | |
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34 | # SpeedyCGI runs END blocks every cycle but somehow keeps object instances |
35 | # hence DIAF |
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 " |
38 | . "codepath.\n" |
39 | ) if $CGI::SpeedyCGI::i_am_speedy; |
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40 | |
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41 | |
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42 | my ($in_global_destruction, $before_is_installed); |
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43 | |
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44 | sub in_global_destruction () { $in_global_destruction } |
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45 | |
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46 | # This block will fire towards the end of the program execution |
47 | # Since there is no way for us to generate an END which will execute *last* |
48 | # this is *NOT 100% INCOMPATIBLE* with XS/${^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. |
51 | # |
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52 | END { |
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53 | $in_global_destruction = 1; |
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54 | } |
55 | |
56 | # threads do not execute the global ENDs (it would be stupid). However |
57 | # one can register a new END via simple string eval within a thread, and |
58 | # achieve the same result. A logical place to do this would be CLONE, which |
59 | # is claimed to run in the context of the new thread. However this does |
60 | # not really seem to be the case - any END evaled in a CLONE is ignored :( |
61 | # Hence blatantly hooking threads::create |
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62 | # |
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63 | if ($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 }' }; |
68 | goto $orig_create; |
69 | }; |
70 | $before_is_installed = 1; |
71 | } |
72 | |
73 | # just in case threads got loaded after us (silly) |
74 | sub CLONE { |
75 | unless ($before_is_installed) { |
76 | require Carp; |
77 | Carp::croak("You must load the 'threads' module before @{[ __PACKAGE__ ]}"); |
78 | } |
79 | } |
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80 | |
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81 | 1; # keep eval happy |
82 | |
83 | PP_IGD |
84 | |
85 | } |
86 | |
87 | 1; # keep require happy |
88 | |
89 | |
90 | __END__ |
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91 | |
92 | =head1 NAME |
93 | |
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94 | Devel::GlobalDestruction - Expose the flag which marks global |
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95 | destruction. |
96 | |
97 | =head1 SYNOPSIS |
98 | |
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99 | package Foo; |
100 | use Devel::GlobalDestruction; |
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101 | |
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102 | use namespace::clean; # to avoid having an "in_global_destruction" method |
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103 | |
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104 | sub DESTROY { |
105 | return if in_global_destruction; |
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106 | |
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107 | do_something_a_little_tricky(); |
108 | } |
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109 | |
110 | =head1 DESCRIPTION |
111 | |
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. |
114 | |
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. |
118 | |
119 | For these constructors you can avoid the mess by simply bailing out if global |
120 | destruction is in effect. |
121 | |
122 | =head1 EXPORTS |
123 | |
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124 | This module uses L<Sub::Exporter::Progressive> so the exports may be renamed, |
125 | aliased, etc. if L<Sub::Exporter> is present. |
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126 | |
127 | =over 4 |
128 | |
129 | =item in_global_destruction |
130 | |
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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>. |
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134 | |
135 | =back |
136 | |
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137 | =head1 AUTHORS |
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138 | |
139 | Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt> |
140 | |
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141 | Florian Ragwitz E<lt>rafl@debian.orgE<gt> |
142 | |
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143 | Jesse Luehrs E<lt>doy@tozt.netE<gt> |
144 | |
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145 | Peter Rabbitson E<lt>ribasushi@cpan.orgE<gt> |
146 | |
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147 | Arthur Axel 'fREW' Schmidt E<lt>frioux@gmail.comE<gt> |
148 | |
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149 | =head1 COPYRIGHT |
150 | |
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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. |
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154 | |
155 | =cut |