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1 | package Devel::GlobalDestruction; |
2 | |
3 | use strict; |
4 | use warnings; |
5 | |
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6 | our $VERSION = '0.09'; |
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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] }; 1' |
17 | or die $@; |
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18 | } |
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19 | # try to load the xs version if it was compiled |
20 | # |
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21 | elsif (eval { |
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22 | require XSLoader; |
23 | XSLoader::load(__PACKAGE__, $VERSION); |
24 | 1; |
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25 | }) { |
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26 | # the eval already installed everything, nothing to do |
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27 | } |
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28 | # We need pure-perl and we are running under -c |
29 | # None of the END-block trickery will work, use a global scope guard instead, |
30 | # as it is more than adequate in this situation |
31 | # The whole thing is in an eval to prevent perl from parsing it in the |
32 | # first place where none of this is needed |
33 | # |
34 | elsif ($^C) { |
35 | eval <<'PP_IGD' or die $@; |
36 | |
37 | my $in_global_destruction; |
38 | |
39 | sub in_global_destruction () { $in_global_destruction } |
40 | |
41 | { |
42 | package Devel::GlobalDestgruction::_MinusC::ScopeGuard; |
43 | sub DESTROY { shift->[0]->() }; |
44 | } |
45 | |
46 | no warnings 'once'; |
47 | $Devel::GlobalDestgruction::_MinusC::guard = bless [sub { |
48 | $in_global_destruction = 1; |
49 | }], 'Devel::GlobalDestgruction::_MinusC::ScopeGuard'; |
50 | |
51 | 1; # keep eval happy |
52 | |
53 | PP_IGD |
54 | } |
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55 | # Not core nor XS |
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56 | # The whole thing is in an eval to prevent perl from parsing it in the |
57 | # first place under perls where none of this is needed |
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58 | # |
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59 | else { |
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60 | eval <<'PP_IGD' or die $@; |
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61 | |
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62 | # SpeedyCGI runs END blocks every cycle but somehow keeps object instances |
63 | # hence DIAF |
64 | die("The pure-perl version of @{[__PACKAGE__]} can not function correctly under CGI::SpeedyCGI. " |
65 | . "Please ensure you have a working compiler, and reinstall @{[__PACKAGE__]} to enable the XS " |
66 | . "codepath.\n" |
67 | ) if $CGI::SpeedyCGI::i_am_speedy; |
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68 | |
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69 | my ($in_global_destruction, $before_is_installed); |
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70 | |
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71 | sub in_global_destruction () { $in_global_destruction } |
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72 | |
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73 | # end_av trick suggested by liz++ |
74 | require B; |
75 | my $add_endblock = sub { |
76 | push @{ B::end_av()->object_2svref }, sub { $in_global_destruction = 1 }; |
77 | }; |
78 | |
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79 | # This block will fire towards the end of the program execution |
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80 | # Use it to inject an END block which is guaranteed to run last |
81 | # (as long as something else doesn't inject yet another block in |
82 | # the same manner afterwards, at which point it hardly matters |
83 | # anyway) |
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84 | # |
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85 | END { $add_endblock->() } |
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86 | |
87 | # threads do not execute the global ENDs (it would be stupid). However |
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88 | # one can register a new thread-local END from within a thread, and |
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89 | # achieve the same result. A logical place to do this would be CLONE, which |
90 | # is claimed to run in the context of the new thread. However this does |
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91 | # not really seem to be the case - any END inserted in a CLONE is ignored :( |
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92 | # Hence blatantly hooking threads::create |
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93 | # |
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94 | if ($INC{'threads.pm'}) { |
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95 | require Scalar::Util; |
96 | |
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97 | my $orig_create = threads->can('create'); |
98 | no warnings 'redefine'; |
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99 | |
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100 | *threads::create = sub { |
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101 | my $class = shift; |
102 | my $target = shift; |
103 | |
104 | unless ( (Scalar::Util::reftype($target)||'') eq 'CODE' ) { |
105 | no strict 'refs'; |
106 | $target = \&{ caller() . "::$target" }; |
107 | } |
108 | |
109 | @_ = ( |
110 | $class, |
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111 | sub { |
112 | # Perls compiled with THREADS_HAVE_PIDS do not copy end_av properly |
113 | # between threads, so B::end_av ends up returning a B::SPECIAL and it |
114 | # goes downhill from there |
115 | # Install a noop END just to be on the safe side |
116 | { local $@; eval 'END {}' } |
117 | $add_endblock->(); |
118 | goto $target |
119 | }, |
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120 | @_, |
121 | ); |
122 | |
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123 | goto $orig_create; |
124 | }; |
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125 | |
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126 | $before_is_installed = 1; |
127 | } |
128 | |
129 | # just in case threads got loaded after us (silly) |
130 | sub CLONE { |
131 | unless ($before_is_installed) { |
132 | require Carp; |
133 | Carp::croak("You must load the 'threads' module before @{[ __PACKAGE__ ]}"); |
134 | } |
135 | } |
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136 | |
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137 | 1; # keep eval happy |
138 | |
139 | PP_IGD |
140 | |
141 | } |
142 | |
143 | 1; # keep require happy |
144 | |
145 | |
146 | __END__ |
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147 | |
148 | =head1 NAME |
149 | |
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150 | Devel::GlobalDestruction - Expose the flag which marks global |
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151 | destruction. |
152 | |
153 | =head1 SYNOPSIS |
154 | |
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155 | package Foo; |
156 | use Devel::GlobalDestruction; |
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157 | |
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158 | use namespace::clean; # to avoid having an "in_global_destruction" method |
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159 | |
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160 | sub DESTROY { |
161 | return if in_global_destruction; |
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162 | |
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163 | do_something_a_little_tricky(); |
164 | } |
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165 | |
166 | =head1 DESCRIPTION |
167 | |
168 | Perl's global destruction is a little tricky to deal with WRT finalizers |
169 | because it's not ordered and objects can sometimes disappear. |
170 | |
171 | Writing defensive destructors is hard and annoying, and usually if global |
172 | destruction is happenning you only need the destructors that free up non |
173 | process local resources to actually execute. |
174 | |
175 | For these constructors you can avoid the mess by simply bailing out if global |
176 | destruction is in effect. |
177 | |
178 | =head1 EXPORTS |
179 | |
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180 | This module uses L<Sub::Exporter::Progressive> so the exports may be renamed, |
181 | aliased, etc. if L<Sub::Exporter> is present. |
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182 | |
183 | =over 4 |
184 | |
185 | =item in_global_destruction |
186 | |
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187 | Returns true if the interpreter is in global destruction. In perl 5.14+, this |
188 | returns C<${^GLOBAL_PHASE} eq 'DESTRUCT'>, and on earlier perls, it returns the |
189 | current value of C<PL_dirty>. |
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190 | |
191 | =back |
192 | |
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193 | =head1 AUTHORS |
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194 | |
195 | Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt> |
196 | |
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197 | Florian Ragwitz E<lt>rafl@debian.orgE<gt> |
198 | |
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199 | Jesse Luehrs E<lt>doy@tozt.netE<gt> |
200 | |
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201 | Peter Rabbitson E<lt>ribasushi@cpan.orgE<gt> |
202 | |
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203 | Arthur Axel 'fREW' Schmidt E<lt>frioux@gmail.comE<gt> |
204 | |
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205 | Elizabeth Mattijsen E<lt>liz@dijkmat.nlE<gt> |
206 | |
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207 | =head1 COPYRIGHT |
208 | |
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209 | Copyright (c) 2008 Yuval Kogman. All rights reserved |
210 | This program is free software; you can redistribute |
211 | it and/or modify it under the same terms as Perl itself. |
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212 | |
213 | =cut |