IO::Async::MergePoint(3pm)				User Contributed Perl Documentation				IO::Async::MergePoint(3pm)

NAME

       "IO::Async::MergePoint" - resynchronise diverged control flow

SYNOPSIS

       This module as now been moved to its own dist of Async::MergePoint.

       It is kept here as a trivial subclass for backward compatibility. Eventually this subclass may be removed. Any code using
       "IO::Async::MergePoint" should instead use Async::MergePoint.

	use Async::MergePoint;

	my $merge = Async::MergePoint->new(
	   needs => [ "leaves", "water" ],

	   on_finished => sub {
	      my %items = @_;
	      # Make tea using $items{leaves} and $items{water}
	   }
	);

	Kettle->boil(
	   on_boiled => sub { $merge->done( "water", $_[0] ) }
	);

	Cupboard->get_tea_leaves(
	   on_fetched => sub { $merge->done( "leaves", $_[0] ) }
	);

DESCRIPTION

       Often in program logic, multiple different steps need to be taken that are independent of each other, but their total result is needed
       before the next step can be taken. In synchonous code, the usual approach is to do them sequentially.

       An "IO::Async"-based program could do this, but if each step involves some IO idle time, better overall performance can often be gained by
       running the steps in parallel. A Async::MergePoint object can then be used to wait for all of the steps to complete, before passing the
       combined result of each step on to the next stage.

       A merge point maintains a set of outstanding operations it is waiting on; these are arbitrary string values provided at the object's
       construction. Each time the "done" method is called, the named item is marked as being complete. When all of the required items are so
       marked, the "on_finished" continuation is invoked.

       When an item is marked as complete, a value can also be provided, which would contain the results of that step. The "on_finished" callback
       is passed a hash (in list form, rather than by reference) of the collected item values.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>

perl v5.14.2							    2012-10-24						IO::Async::MergePoint(3pm)