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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 $CGI::SpeedyCGI::i_am_speedy; |
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40 | |
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41 | my ($in_global_destruction, $before_is_installed); |
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42 | |
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43 | sub in_global_destruction () { $in_global_destruction } |
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44 | |
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45 | # end_av trick suggested by liz++ |
46 | require B; |
47 | my $add_endblock = sub { |
48 | push @{ B::end_av()->object_2svref }, sub { $in_global_destruction = 1 }; |
49 | }; |
50 | |
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51 | # This block will fire towards the end of the program execution |
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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 |
55 | # anyway) |
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56 | # |
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57 | END { $add_endblock->() } |
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58 | |
59 | # threads do not execute the global ENDs (it would be stupid). However |
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60 | # one can register a new thread-local END from within a thread, and |
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61 | # achieve the same result. A logical place to do this would be CLONE, which |
62 | # is claimed to run in the context of the new thread. However this does |
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63 | # not really seem to be the case - any END inserted in a CLONE is ignored :( |
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64 | # Hence blatantly hooking threads::create |
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65 | # |
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66 | if ($INC{'threads.pm'}) { |
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67 | require Scalar::Util; |
68 | |
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69 | my $orig_create = threads->can('create'); |
70 | no warnings 'redefine'; |
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71 | |
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72 | *threads::create = sub { |
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73 | my $class = shift; |
74 | my $target = shift; |
75 | |
76 | unless ( (Scalar::Util::reftype($target)||'') eq 'CODE' ) { |
77 | no strict 'refs'; |
78 | $target = \&{ caller() . "::$target" }; |
79 | } |
80 | |
81 | @_ = ( |
82 | $class, |
83 | sub { $add_endblock->(); goto $target }, |
84 | @_, |
85 | ); |
86 | |
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87 | goto $orig_create; |
88 | }; |
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89 | |
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90 | $before_is_installed = 1; |
91 | } |
92 | |
93 | # just in case threads got loaded after us (silly) |
94 | sub CLONE { |
95 | unless ($before_is_installed) { |
96 | require Carp; |
97 | Carp::croak("You must load the 'threads' module before @{[ __PACKAGE__ ]}"); |
98 | } |
99 | } |
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100 | |
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101 | 1; # keep eval happy |
102 | |
103 | PP_IGD |
104 | |
105 | } |
106 | |
107 | 1; # keep require happy |
108 | |
109 | |
110 | __END__ |
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111 | |
112 | =head1 NAME |
113 | |
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114 | Devel::GlobalDestruction - Expose the flag which marks global |
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115 | destruction. |
116 | |
117 | =head1 SYNOPSIS |
118 | |
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119 | package Foo; |
120 | use Devel::GlobalDestruction; |
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121 | |
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122 | use namespace::clean; # to avoid having an "in_global_destruction" method |
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123 | |
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124 | sub DESTROY { |
125 | return if in_global_destruction; |
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126 | |
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127 | do_something_a_little_tricky(); |
128 | } |
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129 | |
130 | =head1 DESCRIPTION |
131 | |
132 | Perl's global destruction is a little tricky to deal with WRT finalizers |
133 | because it's not ordered and objects can sometimes disappear. |
134 | |
135 | Writing defensive destructors is hard and annoying, and usually if global |
136 | destruction is happenning you only need the destructors that free up non |
137 | process local resources to actually execute. |
138 | |
139 | For these constructors you can avoid the mess by simply bailing out if global |
140 | destruction is in effect. |
141 | |
142 | =head1 EXPORTS |
143 | |
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144 | This module uses L<Sub::Exporter::Progressive> so the exports may be renamed, |
145 | aliased, etc. if L<Sub::Exporter> is present. |
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146 | |
147 | =over 4 |
148 | |
149 | =item in_global_destruction |
150 | |
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151 | Returns true if the interpreter is in global destruction. In perl 5.14+, this |
152 | returns C<${^GLOBAL_PHASE} eq 'DESTRUCT'>, and on earlier perls, it returns the |
153 | current value of C<PL_dirty>. |
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154 | |
155 | =back |
156 | |
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157 | =head1 AUTHORS |
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158 | |
159 | Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt> |
160 | |
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161 | Florian Ragwitz E<lt>rafl@debian.orgE<gt> |
162 | |
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163 | Jesse Luehrs E<lt>doy@tozt.netE<gt> |
164 | |
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165 | Peter Rabbitson E<lt>ribasushi@cpan.orgE<gt> |
166 | |
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167 | Arthur Axel 'fREW' Schmidt E<lt>frioux@gmail.comE<gt> |
168 | |
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169 | Elizabeth Mattijsen E<lt>liz@dijkmat.nlE<gt> |
170 | |
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171 | =head1 COPYRIGHT |
172 | |
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173 | Copyright (c) 2008 Yuval Kogman. All rights reserved |
174 | This program is free software; you can redistribute |
175 | it and/or modify it under the same terms as Perl itself. |
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176 | |
177 | =cut |