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>