use IO::Async::Timer::Countdown; use IO::Async::Loop; my $loop = IO::Async::Loop->new; my $timer = IO::Async::Timer::Countdown->new( delay => 10, on_expire => sub { print "Sorry, your time's up\n"; $loop->stop; }, ); $timer->start; $loop->add( $timer ); $loop->run;
For a "Timer" object that repeatedly runs a callback at regular intervals, see instead IO::Async::Timer::Periodic. For a "Timer" that invokes its callback at a fixed time in the future, see IO::Async::Timer::Absolute.
Once constructed, the timer object will need to be added to the "Loop" before it will work. It will also need to be started by the "start" method.
$expired = $timer->is_expired
Returns true if the Timer has already expired.
$timer->reset
If the timer is running, restart the countdown period from now. If the timer is not running, this method has no effect.
For example, to expire an accepted connection after 30 seconds of inactivity:
... on_accept => sub { my ( $newclient ) = @_; my $watchdog = IO::Async::Timer::Countdown->new( delay => 30, on_expire => sub { my $self = shift; my $stream = $self->parent; $stream->close; }, ); my $stream = IO::Async::Stream->new( handle => $newclient, on_read => sub { my ( $self, $buffref, $eof ) = @_; $watchdog->reset; ... }, on_closed => sub { $watchdog->stop; }, ) ); $stream->add_child( $watchdog ); $watchdog->start; $loop->add( $watchdog ); }
Rather than setting up a lexical variable to store the Stream so that the Timer's "on_expire" closure can call "close" on it, the parent/child relationship between the two Notifier objects is used. At the time the Timer "on_expire" closure is invoked, it will have been added as a child notifier of the Stream; this means the Timer's "parent" method will return the Stream Notifier. This enables it to call "close" without needing to capture a lexical variable, which would create a cyclic reference.
my $timer = IO::Async::Timer::Countdown->new( delay => 60, on_expire => sub { my $self = shift; start_some_operation( on_complete => sub { $self->start }, ); }, ); $timer->start; $loop->add( $timer );
This example invokes the "start_some_operation" function 60 seconds after the previous iteration has indicated it has finished.