Fix spurious ROLLBACK statements when a TxnScopeGuard fails a deferred commit

[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / Storage / TxnScopeGuard.pm

diff --git a/lib/DBIx/Class/Storage/TxnScopeGuard.pm b/lib/DBIx/Class/Storage/TxnScopeGuard.pm
index f686cce..392e354 100644 (file)
--- a/lib/DBIx/Class/Storage/TxnScopeGuard.pm
+++ b/lib/DBIx/Class/Storage/TxnScopeGuard.pm
@@ -2,52 +2,103 @@ package DBIx::Class::Storage::TxnScopeGuard;
 
 use strict;
 use warnings;
-use Carp::Clan qw/^DBIx::Class/;
 use Try::Tiny;
-use Scalar::Util qw/weaken/;
+use Scalar::Util qw(weaken blessed refaddr);
+use DBIx::Class;
+use DBIx::Class::_Util qw(is_exception detected_reinvoked_destructor);
+use DBIx::Class::Carp;
 use namespace::clean;
 
 sub new {
   my ($class, $storage) = @_;
 
+  my $guard = {
+    inactivated => 0,
+    storage => $storage,
+  };
+
+  # we are starting with an already set $@ - in order for things to work we need to
+  # be able to recognize it upon destruction - store its weakref
+  # recording it before doing the txn_begin stuff
+  #
+  # FIXME FRAGILE - any eval that fails but *does not* rethrow between here
+  # and the unwind will trample over $@ and invalidate the entire mechanism
+  # There got to be a saner way of doing this...
+  if (is_exception $@) {
+    weaken(
+      $guard->{existing_exception_ref} = (ref($@) eq '') ? \$@ : $@
+    );
+  }
+
   $storage->txn_begin;
-  my $guard = bless [ 0, $storage, $storage->_dbh ], ref $class || $class;
-  weaken ($guard->[2]);
+
+  weaken( $guard->{dbh} = $storage->_dbh );
+
+  bless $guard, ref $class || $class;
+
   $guard;
 }
 
 sub commit {
   my $self = shift;
 
-  $self->[1]->txn_commit;
-  $self->[0] = 1;
+  $self->{storage}->throw_exception("Refusing to execute multiple commits on scope guard $self")
+    if $self->{inactivated};
+
+  # FIXME - this assumption may be premature: a commit may fail and a rollback
+  # *still* be necessary. Currently I am not aware of such scenarious, but I
+  # also know the deferred constraint handling is *severely* undertested.
+  # Making the change of "fire txn and never come back to this" in order to
+  # address RT#107159, but this *MUST* be reevaluated later.
+  $self->{inactivated} = 1;
+  $self->{storage}->txn_commit;
 }
 
 sub DESTROY {
-  my ($dismiss, $storage) = @{$_[0]};
+  return if &detected_reinvoked_destructor;
 
-  return if $dismiss;
+  my $self = shift;
+
+  return if $self->{inactivated};
 
-  # if our dbh is not ours anymore, the weakref will go undef
-  $storage->_preserve_foreign_dbh;
-  return unless $_[0]->[2];
+  # if our dbh is not ours anymore, the $dbh weakref will go undef
+  $self->{storage}->_verify_pid unless DBIx::Class::_ENV_::BROKEN_FORK;
+  return unless $self->{dbh};
 
-  my $exception = $@;
+  my $exception = $@ if (
+    is_exception $@
+      and
+    (
+      ! defined $self->{existing_exception_ref}
+        or
+      refaddr( ref($@) eq '' ? \$@ : $@ ) != refaddr($self->{existing_exception_ref})
+    )
+  );
 
   {
     local $@;
 
     carp 'A DBIx::Class::Storage::TxnScopeGuard went out of scope without explicit commit or error. Rolling back.'
-      unless $exception;
+      unless defined $exception;
 
     my $rollback_exception;
     # do minimal connectivity check due to weird shit like
     # https://rt.cpan.org/Public/Bug/Display.html?id=62370
-    try { $storage->_seems_connected && $storage->txn_rollback }
+    try { $self->{storage}->_seems_connected && $self->{storage}->txn_rollback }
     catch { $rollback_exception = shift };
 
-    if (defined $rollback_exception && $rollback_exception !~ /DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION/) {
-      if ($exception) {
+    if ( $rollback_exception and (
+      ! defined blessed $rollback_exception
+          or
+      ! $rollback_exception->isa('DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION')
+    ) ) {
+      # append our text - THIS IS A TEMPORARY FIXUP!
+      # a real stackable exception object is in the works
+      if (ref $exception eq 'DBIx::Class::Exception') {
+        $exception->{msg} = "Transaction aborted: $exception->{msg} "
+          ."Rollback failed: ${rollback_exception}";
+      }
+      elsif ($exception) {
         $exception = "Transaction aborted: ${exception} "
           ."Rollback failed: ${rollback_exception}";
       }
@@ -110,13 +161,15 @@ the transaction is rolled back, via L<DBIx::Class::Storage/txn_rollback>
 
 L<DBIx::Class::Schema/txn_scope_guard>.
 
-=head1 AUTHOR
+L<Scope::Guard> by chocolateboy (inspiration for this module)
 
-Ash Berlin, 2008.
+=head1 FURTHER QUESTIONS?
 
-Inspired by L<Scope::Guard> by chocolateboy.
+Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
 
-This module is free software. It may be used, redistributed and/or modified
-under the same terms as Perl itself.
+=head1 COPYRIGHT AND LICENSE
 
-=cut
+This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
+by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
+redistribute it and/or modify it under the same terms as the
+L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.