Rewrite completely broken pure-perl GD detection under threads

[p5sagit/Devel-GlobalDestruction.git] / lib / Devel / GlobalDestruction.pm

diff --git a/lib/Devel/GlobalDestruction.pm b/lib/Devel/GlobalDestruction.pm
index 1afa72a..0854e9e 100644 (file)
--- a/lib/Devel/GlobalDestruction.pm
+++ b/lib/Devel/GlobalDestruction.pm
@@ -3,68 +3,90 @@ package Devel::GlobalDestruction;
 use strict;
 use warnings;
 
-our $VERSION = '0.07';
+our $VERSION = '0.08';
 
 use Sub::Exporter::Progressive -setup => {
-    exports => [ qw(in_global_destruction) ],
-    groups  => { default => [ -all ] },
+  exports => [ qw(in_global_destruction) ],
+  groups  => { default => [ -all ] },
 };
 
 # we run 5.14+ - everything is in core
 #
 if (defined ${^GLOBAL_PHASE}) {
-    eval 'sub in_global_destruction () { ${^GLOBAL_PHASE} eq q[DESTRUCT] }';
+  eval 'sub in_global_destruction () { ${^GLOBAL_PHASE} eq q[DESTRUCT] }';
 }
 # try to load the xs version if it was compiled
 #
 elsif (eval {
-    require XSLoader;
-    XSLoader::load(__PACKAGE__, $VERSION);
-    1;
+  require XSLoader;
+  XSLoader::load(__PACKAGE__, $VERSION);
+  1;
 }) {
-    # the eval already installed everything, nothing to do
+  # the eval already installed everything, nothing to do
 }
 # Not core nor XS
+# The whole thing is in an eval to prevent perl from parsing it in the
+# first place under perls where none of this is needed
 #
 else {
-
-  # SpeedyCGI runs END blocks every cycle but somehow keeps object instances
-  # hence DIAF
-  die("The pure-perl version of @{[__PACKAGE__]} can not function correctly under CGI::SpeedyCGI. "
-    . "Please ensure you have a working compiler, and reinstall @{[__PACKAGE__]} to enable the XS "
-    . "codepath.\n"
-  ) if $CGI::SpeedyCGI::i_am_speedy;
-
   eval <<'PP_IGD' or die $@;
 
+# SpeedyCGI runs END blocks every cycle but somehow keeps object instances
+# hence DIAF
+die("The pure-perl version of @{[__PACKAGE__]} can not function correctly under CGI::SpeedyCGI. "
+  . "Please ensure you have a working compiler, and reinstall @{[__PACKAGE__]} to enable the XS "
+  . "codepath.\n"
+) if $CGI::SpeedyCGI::i_am_speedy;
+
 my ($in_global_destruction, $before_is_installed);
 
 sub in_global_destruction () { $in_global_destruction }
 
+# end_av trick suggested by liz++
+require B;
+my $add_endblock = sub {
+  push @{ B::end_av()->object_2svref }, sub { $in_global_destruction = 1 };
+};
+
 # This block will fire towards the end of the program execution
-# Since there is no way for us to generate an END which will execute *last*
-# this is *NOT 100% INCOMPATIBLE* with XS/${^GLOBAL_PHASE}. We *may* end up
-# with a true in_gloal_destruction() in the middle of another END block
-# There are no practical cases where this matters.
+# Use it to inject an END block which is guaranteed to run last
+# (as long as something else doesn't inject yet another block in
+# the same manner afterwards, at which point it hardly matters
+# anyway)
 #
-END {
-  $in_global_destruction = 1;
-}
+END { $add_endblock->() }
 
 # threads do not execute the global ENDs (it would be stupid). However
-# one can register a new END via simple string eval within a thread, and
+# one can register a new thread-local END from within a thread, and
 # achieve the same result. A logical place to do this would be CLONE, which
 # is claimed to run in the context of the new thread. However this does
-# not really seem to be the case - any END evaled in a CLONE is ignored :(
+# not really seem to be the case - any END inserted in a CLONE is ignored :(
 # Hence blatantly hooking threads::create
 #
 if ($INC{'threads.pm'}) {
+  require Scalar::Util;
+
   my $orig_create = threads->can('create');
   no warnings 'redefine';
+
   *threads::create = sub {
-    { local $@; eval 'END { $in_global_destruction = 1 }' };
+    my $class = shift;
+    my $target = shift;
+
+    unless ( (Scalar::Util::reftype($target)||'') eq 'CODE' ) {
+      no strict 'refs';
+      $target = \&{ caller() . "::$target" };
+    }
+
+    @_ = (
+      $class,
+      sub { $add_endblock->(); goto $target },
+      @_,
+    );
+
     goto $orig_create;
   };
+
   $before_is_installed = 1;
 }
 
@@ -144,6 +166,8 @@ Peter Rabbitson E<lt>ribasushi@cpan.orgE<gt>
 
 Arthur Axel 'fREW' Schmidt E<lt>frioux@gmail.comE<gt>
 
+Elizabeth Mattijsen E<lt>liz@dijkmat.nlE<gt>
+
 =head1 COPYRIGHT
 
     Copyright (c) 2008 Yuval Kogman. All rights reserved