Conservancy/supporters
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Rework the reference counter for begin_work/commit

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This code was clearly not correct as it was.  The main problem is that I
was envisioning begin_work/commit pairs as always matched, but of course
if we die in the middle of a transaction, the counter has to be reset.
That's why we have to set the $dbh->{HandleError} in new() to a
subroutine that does that.

Also, we need to similarly wrap rollback() calls.  When rolling back, we
have to reset the counter as we're not going to commit() (that's the
point).
This commit is contained in:
Bradley M. Kuhn 2015-12-16 19:57:59 -08:00
parent aef01b3031
commit ea60b11965
1 changed files with 43 additions and 7 deletions
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50
Supporters/lib/Supporters.pm
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@ -30,6 +30,8 @@ our $VERSION = '0.02';
use Scalar::Util qw(looks_like_number blessed);
use Mail::RFC822::Address;
my $NESTED_TRANSACTION_COUNTER = 0;
######################################################################
=begin new
@ -65,6 +67,13 @@ sub new ($$) {
die "new: first argument must be a database handle"
unless (defined $dbh and blessed($dbh) =~ /DBI/);
# Turn off AutoCommit, and create our own handler that resets the
# begin_work/commit reference counter.
$dbh->{RaiseError} = 0;
$dbh->{HandleError} = sub {
$NESTED_TRANSACTION_COUNTER = 0;
die $_[0];
};
return $self;
}
######################################################################
@ -453,14 +462,15 @@ This method is a reference counter to keep track of nested begin_work()/commit()
=cut
my $NESTED_TRANSACTION_COUNTER = 0;
sub _beginWork($) {
my($self) = @_;
die "_beginWork: Mismatched begin_work/commit pair in API implementation" if ($NESTED_TRANSACTION_COUNTER < 0);
$self->dbh->begin_work() if ($NESTED_TRANSACTION_COUNTER++ == 1);
if ($NESTED_TRANSACTION_COUNTER < 0) {
die "_beginWork: Mismatched begin_work/commit pair in API implementation";
$NESTED_TRANSACTION_COUNTER = 0;
}
print STDERR "begin work with $NESTED_TRANSACTION_COUNTER\n";
$self->dbh->begin_work() if ($NESTED_TRANSACTION_COUNTER++ == 0);
}
=item _commit()
@ -483,9 +493,35 @@ transactions to verify we don't nest $self->dbh->begin_work()
sub _commit($) {
my($self) = @_;
die "_commit: Mismatched begin_work/commit pair in API implementation" if ($NESTED_TRANSACTION_COUNTER <= 0);
if ($NESTED_TRANSACTION_COUNTER < 0) {
die "_commit: Mismatched begin_work/commit pair in API implementation";
$NESTED_TRANSACTION_COUNTER = 0;
}
$self->dbh->commit() if (--$NESTED_TRANSACTION_COUNTER == 0);
}
$self->dbh->commit() if ($NESTED_TRANSACTION_COUNTER-- == 0);
=item _rollback()
Parameters:
=over
=item $self: current object.
=back
Returns: None.
This method resets the reference counter entirely and calls $dbh->rollback.
=cut
sub _rollback($) {
my($self) = @_;
print STDERR "rollback with $NESTED_TRANSACTION_COUNTER\n";
$NESTED_TRANSACTION_COUNTER = 0;
$self->dbh->rollback();
}
=back