trusty (3) IO::Async::MergePoint.3pm.gz

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>