NAME

       Mojo::IOLoop::Delay - Manage callbacks and control the flow of events

SYNOPSIS

         use Mojo::IOLoop::Delay;

         # Synchronize multiple events
         my $delay = Mojo::IOLoop::Delay->new;
         $delay->on(finish => sub { say 'BOOM!' });
         for my $i (1 .. 10) {
           my $end = $delay->begin;
           Mojo::IOLoop->timer($i => sub {
             say 10 - $i;
             $end->();
           });
         }
         $delay->wait unless Mojo::IOLoop->is_running;

         # Sequentialize multiple events
         my $delay = Mojo::IOLoop::Delay->new;
         $delay->steps(

           # First step (simple timer)
           sub {
             my $delay = shift;
             Mojo::IOLoop->timer(2 => $delay->begin);
             say 'Second step in 2 seconds.';
           },

           # Second step (parallel timers)
           sub {
             my ($delay, @args) = @_;
             Mojo::IOLoop->timer(1 => $delay->begin);
             Mojo::IOLoop->timer(3 => $delay->begin);
             say 'Third step in 3 seconds.';
           },

           # Third step (the end)
           sub {
             my ($delay, @args) = @_;
             say 'And done after 5 seconds total.';
           }
         );
         $delay->wait unless Mojo::IOLoop->is_running;

DESCRIPTION

       Mojo::IOLoop::Delay manages callbacks and controls the flow of events for Mojo::IOLoop.

EVENTS

       Mojo::IOLoop::Delay inherits all events from Mojo::EventEmitter and can emit the following
       new ones.

   error
         $delay->on(error => sub {
           my ($delay, $err) = @_;
           ...
         });

       Emitted if an error occurs in one of the steps, breaking the chain, fatal if unhandled.

   finish
         $delay->on(finish => sub {
           my ($delay, @args) = @_;
           ...
         });

       Emitted once the active event counter reaches zero and there are no more steps.

ATTRIBUTES

       Mojo::IOLoop::Delay implements the following attributes.

   ioloop
         my $ioloop = $delay->ioloop;
         $delay     = $delay->ioloop(Mojo::IOLoop->new);

       Event loop object to control, defaults to the global Mojo::IOLoop singleton.

METHODS

       Mojo::IOLoop::Delay inherits all methods from Mojo::EventEmitter and implements the
       following new ones.

   begin
         my $without_first_arg = $delay->begin;
         my $with_first_arg    = $delay->begin(0);

       Increment active event counter, the returned callback can be used to decrement the active
       event counter again. Arguments passed to the callback are queued in the right order for
       the next step or "finish" event and "wait" method, the first argument will be ignored by
       default.

         # Capture all arguments
         my $delay = Mojo::IOLoop->delay;
         Mojo::IOLoop->client({port => 3000} => $delay->begin(0));
         my ($loop, $err, $stream) = $delay->wait;

   steps
         $delay = $delay->steps(sub {...}, sub {...});

       Sequentialize multiple events, the first callback will run right away, and the next one
       once the active event counter reaches zero. This chain will continue until there are no
       more callbacks, a callback does not increment the active event counter or an error occurs
       in a callback.

   wait
         my $arg  = $delay->wait;
         my @args = $delay->wait;

       Start "ioloop" and stop it again once an "error" or "finish" event gets emitted, only
       works when "ioloop" is not running already.

         # Use the "finish" event to synchronize portably
         $delay->on(finish => sub {
           my ($delay, @args) = @_;
           ...
         });
         $delay->wait unless $delay->ioloop->is_running;

SEE ALSO

       Mojolicious, Mojolicious::Guides, <http://mojolicio.us>.