AnyEvent::FIFO - Simple FIFO Callback Dispatch

    my $fifo = AnyEvent::FIFO->new(
        max_active => 1, # max "concurrent" callbacks to execute per slot
    );

    # send to the "default" slot
    $fifo->push( \&callback, @args );

    # send to the "slot" slot
    $fifo->push( "slot", \&callback, @args );

    # dispatch is done automatically

    sub callback {
        my ($guard, @args) = @_;

        # next callback will be executed when $guard is undef'ed or
        # when it goes out of scope
    }

AnyEvent::FIFO is a simple FIFO queue to dispatch events in order.

If you use regular watchers and register callbacks from various places in your program, you're not necessarily guaranteed that the callbacks will be executed in the order that you expect. By using this module, you can register callbacks and they will be executed in that particular order.

max_active => $number

Number of concurrent callbacks to be executed per slot.

$slot

The name of the slot that this callback should be registered to. If $slot is not specified, "__default__" is used.

$cb

The callback to be executed. Receives a "guard" object, and a list of arguments, as specied in @args.

$guard is the actually trigger that kicks the next callback to be executed, so you should keep it "alive" while you need it. For example, if you need to make an http request to declare the callback done, you should do something like this:

    $fifo->push( sub {
        my ($guard, @args) = @_;

        http_get $uri, sub {
            ...
            undef $guard; # *NOW* the callback is done
        }
    } );

@args

List of extra arguments that gets passed to the callback

Attemps to drain the queue, if possible. You DO NOT need to call this method by yourself. It's handled automatically

This module is basically a generalisation of the FIFO queue used in AnyEvent::HTTP by Marc Lehman.

(c) Daisuke Maki <<daisuke@endeworks.jp> > 2010