From: Peter Rabbitson <ribasushi@cpan.org>
Date: Tue, 27 Apr 2010 17:11:45 +0000 (+0000)
Subject: Fix global destruction problems
X-Git-Tag: v0.08122~96
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?p=dbsrgits%2FDBIx-Class.git;a=commitdiff_plain;h=aa0163d42e50f63a1bd40d910654008ee8ca7a09

Fix global destruction problems
---

diff --git a/Changes b/Changes
index 0ca073b..5a6f7ce 100644
--- a/Changes
+++ b/Changes
@@ -1,6 +1,10 @@
 Revision history for DBIx::Class
 
-        - Add a warning to load_namespaces if a class in ResultSet/ is not a subclass of DBIx::Class::ResultSet
+        - Add a warning to load_namespaces if a class in ResultSet/
+          is not a subclass of DBIx::Class::ResultSet
+        - ::Storage::DBI now correctly preserves a parent $dbh from
+          terminating children, even during interpreter global
+          out-of-order destruction
         - InflateColumn::DateTime support for MSSQL via DBD::Sybase
         - Millisecond precision support for MSSQL datetimes for
           InflateColumn::DateTime
diff --git a/lib/DBIx/Class/Storage/DBI.pm b/lib/DBIx/Class/Storage/DBI.pm
index 68593da..ac90066 100644
--- a/lib/DBIx/Class/Storage/DBI.pm
+++ b/lib/DBIx/Class/Storage/DBI.pm
@@ -116,9 +116,102 @@ sub new {
   $new->{_in_dbh_do} = 0;
   $new->{_dbh_gen} = 0;
 
+  # read below to see what this does
+  $new->_arm_global_destructor;
+
   $new;
 }
 
+# This is hack to work around perl shooting stuff in random
+# order on exit(). If we do not walk the remaining storage
+# objects in an END block, there is a *small but real* chance
+# of a fork()ed child to kill the parent's shared DBI handle,
+# *before perl reaches the DESTROY in this package*
+# Yes, it is ugly and effective.
+{
+  my %seek_and_destroy;
+
+  sub _arm_global_destructor {
+    my $self = shift;
+    my $key = Scalar::Util::refaddr ($self);
+    $seek_and_destroy{$key} = $self;
+    Scalar::Util::weaken ($seek_and_destroy{$key});
+  }
+
+  END {
+    local $?; # just in case the DBI destructor changes it somehow
+
+    # destroy just the object if not native to this process/thread
+    $_->_preserve_foreign_dbh for (grep
+      { defined $_ }
+      values %seek_and_destroy
+    );
+  }
+}
+
+sub DESTROY {
+  my $self = shift;
+
+  # destroy just the object if not native to this process/thread
+  $self->_preserve_foreign_dbh;
+
+  # some databases need this to stop spewing warnings
+  if (my $dbh = $self->_dbh) {
+    local $@;
+    eval {
+      %{ $dbh->{CachedKids} } = ();
+      $dbh->disconnect;
+    };
+  }
+
+  $self->_dbh(undef);
+}
+
+sub _preserve_foreign_dbh {
+  my $self = shift;
+
+  return unless $self->_dbh;
+
+  $self->_verify_tid;
+
+  return unless $self->_dbh;
+
+  $self->_verify_pid;
+
+}
+
+# handle pid changes correctly - do not destroy parent's connection
+sub _verify_pid {
+  my $self = shift;
+
+  return if ( defined $self->_conn_pid and $self->_conn_pid == $$ );
+
+  $self->_dbh->{InactiveDestroy} = 1;
+  $self->_dbh(undef);
+  $self->{_dbh_gen}++;
+
+  return;
+}
+
+# very similar to above, but seems to FAIL if I set InactiveDestroy
+sub _verify_tid {
+  my $self = shift;
+
+  if ( ! defined $self->_conn_tid ) {
+    return; # no threads
+  }
+  elsif ( $self->_conn_tid == threads->tid ) {
+    return; # same thread
+  }
+
+  #$self->_dbh->{InactiveDestroy} = 1;  # why does t/51threads.t fail...?
+  $self->_dbh(undef);
+  $self->{_dbh_gen}++;
+
+  return;
+}
+
+
 =head2 connect_info
 
 This method is normally called by L<DBIx::Class::Schema/connection>, which
@@ -804,19 +897,11 @@ sub connected {
 sub _seems_connected {
   my $self = shift;
 
+  $self->_preserve_foreign_dbh;
+
   my $dbh = $self->_dbh
     or return 0;
 
-  if(defined $self->_conn_tid && $self->_conn_tid != threads->tid) {
-    $self->_dbh(undef);
-    $self->{_dbh_gen}++;
-    return 0;
-  }
-  else {
-    $self->_verify_pid;
-    return 0 if !$self->_dbh;
-  }
-
   return $dbh->FETCH('Active');
 }
 
@@ -828,20 +913,6 @@ sub _ping {
   return $dbh->ping;
 }
 
-# handle pid changes correctly
-#  NOTE: assumes $self->_dbh is a valid $dbh
-sub _verify_pid {
-  my ($self) = @_;
-
-  return if defined $self->_conn_pid && $self->_conn_pid == $$;
-
-  $self->_dbh->{InactiveDestroy} = 1;
-  $self->_dbh(undef);
-  $self->{_dbh_gen}++;
-
-  return;
-}
-
 sub ensure_connected {
   my ($self) = @_;
 
@@ -874,7 +945,7 @@ sub dbh {
 # this is the internal "get dbh or connect (don't check)" method
 sub _get_dbh {
   my $self = shift;
-  $self->_verify_pid if $self->_dbh;
+  $self->_preserve_foreign_dbh;
   $self->_populate_dbh unless $self->_dbh;
   return $self->_dbh;
 }
@@ -2653,23 +2724,6 @@ sub relname_to_table_alias {
   return $alias;
 }
 
-sub DESTROY {
-  my $self = shift;
-
-  $self->_verify_pid if $self->_dbh;
-
-  # some databases need this to stop spewing warnings
-  if (my $dbh = $self->_dbh) {
-    local $@;
-    eval {
-      %{ $dbh->{CachedKids} } = ();
-      $dbh->disconnect;
-    };
-  }
-
-  $self->_dbh(undef);
-}
-
 1;
 
 =head1 USAGE NOTES