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Sebastian Riedel


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


  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;

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

    # 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.';

  # Wait for events if necessary
  $delay->wait unless Mojo::IOLoop->is_running;


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


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


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

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


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


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

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


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


  my $cb = $delay->begin;
  my $cb = $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;


  $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 or a callback does not increment the active event counter.


  my @args = $delay->wait;

Start ioloop and stop it again once the 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;


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