IO::Async::MergePoint(User Contributed Perl DocumentatIO::Async::MergePoint(3)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 v5.18.2 2014-05-14 IO::Async::MergePoint(3)
