1IO::Async::Timer::CountUdsoewrn(C3o)ntributed Perl DocumIeOn:t:aAtsiyonnc::Timer::Countdown(3)
2
3
4

NAME

6       "IO::Async::Timer::Countdown" - event callback after a fixed delay
7

SYNOPSIS

9        use IO::Async::Timer::Countdown;
10
11        use IO::Async::Loop;
12        my $loop = IO::Async::Loop->new();
13
14        my $timer = IO::Async::Timer::Countdown->new(
15           delay => 10,
16
17           on_expire => sub {
18              print "Sorry, your time's up\n";
19              $loop->loop_stop;
20           },
21        );
22
23        $timer->start;
24
25        $loop->add( $timer );
26
27        $loop->loop_forever;
28

DESCRIPTION

30       This module provides a subclass of IO::Async::Timer for implementing
31       one-shot fixed delays. The object implements a countdown timer, which
32       invokes its callback after the given period from when it was started.
33       After it has expired the Timer may be started again, when it will wait
34       the same period then invoke the callback again. A timer that is
35       currently running may be stopped or reset.
36
37       For a "Timer" object that repeatedly runs a callback at regular
38       intervals, see instead IO::Async::Timer::Periodic.
39
40       This object may be used in one of two ways; with a callback function,
41       or as a base class.
42
43       Callbacks
44           If the "on_expire" key is supplied to the constructor, it should
45           contain a CODE reference to a callback function to be invoked at
46           the appropriate time:
47
48            $on_expire->( $self )
49
50       Base Class
51           If a subclass is built, then it can override the "on_expire"
52           method.
53
54            $self->on_expire()
55

PARAMETERS

57       The following named parameters may be passed to "new" or "configure":
58
59       on_expire => CODE
60               CODE reference to callback to invoke when the timer expires. If
61               not supplied, the subclass method will be called instead.
62
63       delay => NUM
64               The delay in seconds after starting the timer until it expires.
65               Cannot be changed if the timer is running.
66
67       Once constructed, the timer object will need to be added to the "Loop"
68       before it will work. It will also need to be started by the "start"
69       method.
70
71   $timer->reset
72       If the timer is running, restart the countdown period from now. If the
73       timer is not running, this method has no effect.
74

EXAMPLES

76   Watchdog Timer
77       Because the "reset" method restarts a running countdown timer back to
78       its full period, it can be used to implement a watchdog timer. This is
79       a timer which will not expire provided the method is called at least as
80       often as it is configured. If the method fails to be called, the timer
81       will eventually expire and run its callback.
82
83       For example, to expire an accepted connection after 30 seconds of
84       inactivity:
85
86        ...
87
88        on_accept => sub {
89           my ( $newclient ) = @_;
90
91           my $stream;
92
93           my $watchdog = IO::Async::Timer::Countdown->new(
94              delay => 30,
95
96              on_expire => sub { $stream->close },
97           );
98           $stream->add_child( $watchdog );
99
100           $stream = IO::Async::Stream->new(
101              handle => $newclient,
102
103              on_read => sub {
104                 my ( $self, $buffref, $closed ) = @_;
105                 $watchdog->reset;
106
107                 ...
108              },
109
110              on_closed => sub {
111                 $watchdog->stop;
112              },
113           ) );
114
115           $watchdog->start;
116
117           $loop->add( $watchdog );
118        }
119

AUTHOR

121       Paul Evans <leonerd@leonerd.org.uk>
122
123
124
125perl v5.12.1                      2010-06-09    IO::Async::Timer::Countdown(3)
Impressum