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lib/Data/Consumer.pm  view on Meta::CPAN

=head2 The Consumer Pattern

The consumer pattern is where code wants to consume an 'atomic' resource
piece by piece. The consuming code doesn't really want to worry much
about how they got the piece, a task that should be handled by the framework.
The consumer subclasses assume that the resource can be modeled as a 
queue (that there is some ordering principle by which they can be processed 
in a predictable sequence). The consume pattern in full glory is something 
very close to the following following pseudo code. The items marked with 
asterisks are where user callbacks may be invoked:

    DO
        RESET TO THE BEGINNING OF THE QUEUE
	WHILE QUEUE NOT EMPTY AND CAN *PROCEED*
	    ACQUIRE NEXT ITEM TO PROCESS FROM QUEUE
	    MARK AS 'WORKING'
	    *PROCESS* ITEM 
	    IF PROCESSING FAILED
		MARK AS 'FAILED'
	    OTHERWISE 

lib/Data/Consumer.pm  view on Meta::CPAN

        my $id= $self->last_id;
        $self->{ignore}{$id}++;
        $self->leave;
    }
    return $self;
}

=head2 $consumer->fail($message)

Same as doing C<die($message)> from within a consume/process callback except
that no exception is thrown (no C<$SIG{__DIE__}> callbacks are invoked) and
the error is deferred until the callback actually returns.

Typically used as

    return $consumer->fail;

from within a consumer() callback.

Returns the $consumer object.