add comment to explain use of main_start

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

diff --git a/lib/Devel/GlobalDestruction.pm b/lib/Devel/GlobalDestruction.pm
index 0854e9e..25b8958 100644 (file)
--- a/lib/Devel/GlobalDestruction.pm
+++ b/lib/Devel/GlobalDestruction.pm
@@ -3,7 +3,7 @@ package Devel::GlobalDestruction;
 use strict;
 use warnings;
 
-our $VERSION = '0.08';
+our $VERSION = '0.09';
 
 use Sub::Exporter::Progressive -setup => {
   exports => [ qw(in_global_destruction) ],
@@ -13,7 +13,8 @@ use Sub::Exporter::Progressive -setup => {
 # 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] }; 1'
+    or die $@;
 }
 # try to load the xs version if it was compiled
 #
@@ -24,84 +25,12 @@ elsif (eval {
 }) {
   # 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 {
-  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
-# 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 { $add_endblock->() }
-
-# threads do not execute the global ENDs (it would be stupid). However
-# one can register a new thread-local END from within a thread, and
-# achieve the same result. A logical place to do this would be CLONE, which
-# is claimed to run in the context of the new thread. However this does
-# not really seem to be the case - any END inserted in a CLONE is ignored :(
-# Hence blatantly hooking threads::create
-#
-if ($INC{'threads.pm'}) {
-  require Scalar::Util;
-
-  my $orig_create = threads->can('create');
-  no warnings 'redefine';
-
-  *threads::create = sub {
-    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;
-  };
-
-  $before_is_installed = 1;
-}
-
-# just in case threads got loaded after us (silly)
-sub CLONE {
-  unless ($before_is_installed) {
-    require Carp;
-    Carp::croak("You must load the 'threads' module before @{[ __PACKAGE__ ]}");
-  }
-}
-
-1;  # keep eval happy
-
-PP_IGD
-
+  # internally, PL_main_start is nulled immediately before entering global destruction
+  # and we can use B to detect that
+  require B;
+  eval 'sub in_global_destruction () { B::main_start()->isa(q[B::NULL]) }; 1'
+    or die $@;
 }
 
 1;  # keep require happy