1 |
=head1 NAME |
2 |
|
3 |
EV - perl interface to libev, a high performance full-featured event loop |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
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use EV; |
8 |
|
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# TIMERS |
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|
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my $w = EV::timer 2, 0, sub { |
12 |
warn "is called after 2s"; |
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}; |
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|
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my $w = EV::timer 2, 2, sub { |
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warn "is called roughly every 2s (repeat = 2)"; |
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}; |
18 |
|
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undef $w; # destroy event watcher again |
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|
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my $w = EV::periodic 0, 60, 0, sub { |
22 |
warn "is called every minute, on the minute, exactly"; |
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}; |
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|
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# IO |
26 |
|
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my $w = EV::io *STDIN, EV::READ, sub { |
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my ($w, $revents) = @_; # all callbacks receive the watcher and event mask |
29 |
warn "stdin is readable, you entered: ", <STDIN>; |
30 |
}; |
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|
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# SIGNALS |
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|
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my $w = EV::signal 'QUIT', sub { |
35 |
warn "sigquit received\n"; |
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}; |
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|
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# CHILD/PID STATUS CHANGES |
39 |
|
40 |
my $w = EV::child 666, sub { |
41 |
my ($w, $revents) = @_; |
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my $status = $w->rstatus; |
43 |
}; |
44 |
|
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# MAINLOOP |
46 |
EV::loop; # loop until EV::unloop is called or all watchers stop |
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EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
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EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
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|
50 |
=head1 DESCRIPTION |
51 |
|
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This module provides an interface to libev |
53 |
(L<http://software.schmorp.de/pkg/libev.html>). |
54 |
|
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=cut |
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|
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package EV; |
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|
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use strict; |
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|
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BEGIN { |
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our $VERSION = '1.3'; |
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use XSLoader; |
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XSLoader::load "EV", $VERSION; |
65 |
} |
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|
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@EV::IO::ISA = |
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@EV::Timer::ISA = |
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@EV::Periodic::ISA = |
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@EV::Signal::ISA = |
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@EV::Idle::ISA = |
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@EV::Prepare::ISA = |
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@EV::Check::ISA = |
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@EV::Child::ISA = "EV::Watcher"; |
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|
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=head1 BASIC INTERFACE |
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|
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=over 4 |
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|
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=item $EV::DIED |
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|
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Must contain a reference to a function that is called when a callback |
83 |
throws an exception (with $@ containing thr error). The default prints an |
84 |
informative message and continues. |
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|
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If this callback throws an exception it will be silently ignored. |
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|
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=item $time = EV::time |
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|
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Returns the current time in (fractional) seconds since the epoch. |
91 |
|
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=item $time = EV::now |
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|
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Returns the time the last event loop iteration has been started. This |
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is the time that (relative) timers are based on, and refering to it is |
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usually faster then calling EV::time. |
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|
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=item $method = EV::method |
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|
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Returns an integer describing the backend used by libev (EV::METHOD_SELECT |
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or EV::METHOD_EPOLL). |
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|
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=item EV::loop [$flags] |
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|
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Begin checking for events and calling callbacks. It returns when a |
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callback calls EV::unloop. |
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|
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The $flags argument can be one of the following: |
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|
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0 as above |
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EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
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EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
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|
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=item EV::unloop [$how] |
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|
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When called with no arguments or an argument of EV::UNLOOP_ONE, makes the |
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innermost call to EV::loop return. |
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|
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When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as |
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fast as possible. |
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|
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=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) |
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|
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This function rolls together an I/O and a timer watcher for a single |
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one-shot event without the need for managing a watcher object. |
126 |
|
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If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events> |
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must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ |
129 |
| EV::WRITE>, indicating the type of I/O event you want to wait for. If |
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you do not want to wait for some I/O event, specify C<undef> for |
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C<$fh_or_undef> and C<0> for C<$events>). |
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|
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If timeout is C<undef> or negative, then there will be no |
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timeout. Otherwise a EV::timer with this value will be started. |
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|
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When an error occurs or either the timeout or I/O watcher triggers, then |
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the callback will be called with the received event set (in general |
138 |
you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>, |
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C<EV::WRITE> and C<EV::TIMEOUT>). |
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|
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EV::once doesn't return anything: the watchers stay active till either |
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of them triggers, then they will be stopped and freed, and the callback |
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invoked. |
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|
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=back |
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|
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=head2 WATCHER |
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|
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A watcher is an object that gets created to record your interest in some |
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event. For instance, if you want to wait for STDIN to become readable, you |
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would create an EV::io watcher for that: |
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|
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my $watcher = EV::io *STDIN, EV::READ, sub { |
154 |
my ($watcher, $revents) = @_; |
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warn "yeah, STDIN should not be readable without blocking!\n" |
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}; |
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|
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All watchers can be active (waiting for events) or inactive (paused). Only |
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active watchers will have their callbacks invoked. All callbacks will be |
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called with at least two arguments: the watcher and a bitmask of received |
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events. |
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|
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Each watcher type has its associated bit in revents, so you can use the |
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same callback for multiple watchers. The event mask is named after the |
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type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
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EV::periodic sets EV::PERIODIC and so on, with the exception of IO events |
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(which can set both EV::READ and EV::WRITE bits), and EV::timer (which |
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uses EV::TIMEOUT). |
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|
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In the rare case where one wants to create a watcher but not start it at |
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the same time, each constructor has a variant with a trailing C<_ns> in |
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its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. |
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|
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Please note that a watcher will automatically be stopped when the watcher |
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object is destroyed, so you I<need> to keep the watcher objects returned by |
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the constructors. |
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|
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Also, all methods changing some aspect of a watcher (->set, ->priority, |
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->fh and so on) automatically stop and start it again if it is active, |
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which means pending events get lost. |
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|
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=head2 WATCHER TYPES |
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|
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Now lets move to the existing watcher types and asociated methods. |
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|
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The following methods are available for all watchers. Then followes a |
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description of each watcher constructor (EV::io, EV::timer, EV::periodic, |
188 |
EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by |
189 |
any type-specific methods (if any). |
190 |
|
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=over 4 |
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|
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=item $w->start |
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|
195 |
Starts a watcher if it isn't active already. Does nothing to an already |
196 |
active watcher. By default, all watchers start out in the active state |
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(see the description of the C<_ns> variants if you need stopped watchers). |
198 |
|
199 |
=item $w->stop |
200 |
|
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Stop a watcher if it is active. Also clear any pending events (events that |
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have been received but that didn't yet result in a callback invocation), |
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regardless of wether the watcher was active or not. |
204 |
|
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=item $bool = $w->is_active |
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|
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Returns true if the watcher is active, false otherwise. |
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|
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=item $current_data = $w->data |
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|
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=item $old_data = $w->data ($new_data) |
212 |
|
213 |
Queries a freely usable data scalar on the watcher and optionally changes |
214 |
it. This is a way to associate custom data with a watcher: |
215 |
|
216 |
my $w = EV::timer 60, 0, sub { |
217 |
warn $_[0]->data; |
218 |
}; |
219 |
$w->data ("print me!"); |
220 |
|
221 |
=item $current_cb = $w->cb |
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|
223 |
=item $old_cb = $w->cb ($new_cb) |
224 |
|
225 |
Queries the callback on the watcher and optionally changes it. You can do |
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this at any time without the watcher restarting. |
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|
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=item $current_priority = $w->priority |
229 |
|
230 |
=item $old_priority = $w->priority ($new_priority) |
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|
232 |
Queries the priority on the watcher and optionally changes it. Pending |
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watchers with higher priority will be invoked first. The valid range of |
234 |
priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default |
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-2). If the priority is outside this range it will automatically be |
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normalised to the nearest valid priority. |
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|
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The default priority of any newly-created watcher is 0. |
239 |
|
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Note that the priority semantics have not yet been fleshed out and are |
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subject to almost certain change. |
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|
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=item $w->trigger ($revents) |
244 |
|
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Call the callback *now* with the given event mask. |
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|
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=item $previous_state = $w->keepalive ($bool) |
248 |
|
249 |
Normally, C<EV::loop> will return when there are no active watchers |
250 |
(which is a "deadlock" because no progress can be made anymore). This is |
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convinient because it allows you to start your watchers (and your jobs), |
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call C<EV::loop> once and when it returns you know that all your jobs are |
253 |
finished (or they forgot to register some watchers for their task :). |
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|
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Sometimes, however, this gets in your way, for example when you the module |
256 |
that calls C<EV::loop> (usually the main program) is not the same module |
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as a long-living watcher (for example a DNS client module written by |
258 |
somebody else even). Then you might want any outstanding requests to be |
259 |
handled, but you would not want to keep C<EV::loop> from returning just |
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because you happen to have this long-running UDP port watcher. |
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|
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In this case you can clear the keepalive status, which means that even |
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though your watcher is active, it won't keep C<EV::loop> from returning. |
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|
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The initial value for keepalive is true (enabled), and you cna change it |
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any time. |
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|
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Example: Register an IO watcher for some UDP socket but do not keep the |
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event loop from running just because of that watcher. |
270 |
|
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my $udp_socket = ... |
272 |
my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; |
273 |
$udp_watcher->keepalive (0); |
274 |
|
275 |
=item $w = EV::io $fileno_or_fh, $eventmask, $callback |
276 |
|
277 |
=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
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|
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As long as the returned watcher object is alive, call the C<$callback> |
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when the events specified in C<$eventmask>. |
281 |
|
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The $eventmask can be one or more of these constants ORed together: |
283 |
|
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EV::READ wait until read() wouldn't block anymore |
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EV::WRITE wait until write() wouldn't block anymore |
286 |
|
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The C<io_ns> variant doesn't start (activate) the newly created watcher. |
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|
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=item $w->set ($fileno_or_fh, $eventmask) |
290 |
|
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Reconfigures the watcher, see the constructor above for details. Can be |
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called at any time. |
293 |
|
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=item $current_fh = $w->fh |
295 |
|
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=item $old_fh = $w->fh ($new_fh) |
297 |
|
298 |
Returns the previously set filehandle and optionally set a new one. |
299 |
|
300 |
=item $current_eventmask = $w->events |
301 |
|
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=item $old_eventmask = $w->events ($new_eventmask) |
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|
304 |
Returns the previously set event mask and optionally set a new one. |
305 |
|
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|
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=item $w = EV::timer $after, $repeat, $callback |
308 |
|
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=item $w = EV::timer_ns $after, $repeat, $callback |
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|
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Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, |
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the timer will be restarted (with the $repeat value as $after) after the |
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callback returns. |
314 |
|
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This means that the callback would be called roughly after C<$after> |
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seconds, and then every C<$repeat> seconds. The timer does his best not |
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to drift, but it will not invoke the timer more often then once per event |
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loop iteration, and might drift in other cases. If that isn't acceptable, |
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look at EV::periodic, which can provide long-term stable timers. |
320 |
|
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The timer is based on a monotonic clock, that is, if somebody is sitting |
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in front of the machine while the timer is running and changes the system |
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clock, the timer will nevertheless run (roughly) the same time. |
324 |
|
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The C<timer_ns> variant doesn't start (activate) the newly created watcher. |
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|
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=item $w->set ($after, $repeat) |
328 |
|
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Reconfigures the watcher, see the constructor above for details. Can be at |
330 |
any time. |
331 |
|
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=item $w->again |
333 |
|
334 |
Similar to the C<start> method, but has special semantics for repeating timers: |
335 |
|
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If the timer is active and non-repeating, it will be stopped. |
337 |
|
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If the timer is active and repeating, reset the timeout to occur |
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C<$repeat> seconds after now. |
340 |
|
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If the timer is inactive and repeating, start it using the repeat value. |
342 |
|
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Otherwise do nothing. |
344 |
|
345 |
This behaviour is useful when you have a timeout for some IO |
346 |
operation. You create a timer object with the same value for C<$after> and |
347 |
C<$repeat>, and then, in the read/write watcher, run the C<again> method |
348 |
on the timeout. |
349 |
|
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|
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=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
352 |
|
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=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
354 |
|
355 |
Similar to EV::timer, but is not based on relative timeouts but on |
356 |
absolute times. Apart from creating "simple" timers that trigger "at" the |
357 |
specified time, it can also be used for non-drifting absolute timers and |
358 |
more complex, cron-like, setups that are not adversely affected by time |
359 |
jumps (i.e. when the system clock is changed by explicit date -s or other |
360 |
means such as ntpd). It is also the most complex watcher type in EV. |
361 |
|
362 |
It has three distinct "modes": |
363 |
|
364 |
=over 4 |
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|
366 |
=item * absolute timer ($interval = $reschedule_cb = 0) |
367 |
|
368 |
This time simply fires at the wallclock time C<$at> and doesn't repeat. It |
369 |
will not adjust when a time jump occurs, that is, if it is to be run |
370 |
at January 1st 2011 then it will run when the system time reaches or |
371 |
surpasses this time. |
372 |
|
373 |
=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) |
374 |
|
375 |
In this mode the watcher will always be scheduled to time out at the |
376 |
next C<$at + N * $interval> time (for some integer N) and then repeat, |
377 |
regardless of any time jumps. |
378 |
|
379 |
This can be used to create timers that do not drift with respect to system |
380 |
time: |
381 |
|
382 |
my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; |
383 |
|
384 |
That doesn't mean there will always be 3600 seconds in between triggers, |
385 |
but only that the the clalback will be called when the system time shows a |
386 |
full hour (UTC). |
387 |
|
388 |
Another way to think about it (for the mathematically inclined) is that |
389 |
EV::periodic will try to run the callback in this mode at the next |
390 |
possible time where C<$time = $at (mod $interval)>, regardless of any time |
391 |
jumps. |
392 |
|
393 |
=item * manual reschedule mode ($reschedule_cb = coderef) |
394 |
|
395 |
In this mode $interval and $at are both being ignored. Instead, each |
396 |
time the periodic watcher gets scheduled, the reschedule callback |
397 |
($reschedule_cb) will be called with the watcher as first, and the current |
398 |
time as second argument. |
399 |
|
400 |
I<This callback MUST NOT stop or destroy this or any other periodic |
401 |
watcher, ever>. If you need to stop it, return 1e30 and stop it |
402 |
afterwards. |
403 |
|
404 |
It must return the next time to trigger, based on the passed time value |
405 |
(that is, the lowest time value larger than to the second argument). It |
406 |
will usually be called just before the callback will be triggered, but |
407 |
might be called at other times, too. |
408 |
|
409 |
This can be used to create very complex timers, such as a timer that |
410 |
triggers on each midnight, local time (actually 24 hours after the last |
411 |
midnight, to keep the example simple. If you know a way to do it correctly |
412 |
in about the same space (without requiring elaborate modules), drop me a |
413 |
note :): |
414 |
|
415 |
my $daily = EV::periodic 0, 0, sub { |
416 |
my ($w, $now) = @_; |
417 |
|
418 |
use Time::Local (); |
419 |
my (undef, undef, undef, $d, $m, $y) = localtime $now; |
420 |
86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y |
421 |
}, sub { |
422 |
print "it's midnight or likely shortly after, now\n"; |
423 |
}; |
424 |
|
425 |
=back |
426 |
|
427 |
The C<periodic_ns> variant doesn't start (activate) the newly created watcher. |
428 |
|
429 |
=item $w->set ($at, $interval, $reschedule_cb) |
430 |
|
431 |
Reconfigures the watcher, see the constructor above for details. Can be at |
432 |
any time. |
433 |
|
434 |
=item $w->again |
435 |
|
436 |
Simply stops and starts the watcher again. |
437 |
|
438 |
|
439 |
=item $w = EV::signal $signal, $callback |
440 |
|
441 |
=item $w = EV::signal_ns $signal, $callback |
442 |
|
443 |
Call the callback when $signal is received (the signal can be specified |
444 |
by number or by name, just as with kill or %SIG). |
445 |
|
446 |
EV will grab the signal for the process (the kernel only allows one |
447 |
component to receive a signal at a time) when you start a signal watcher, |
448 |
and removes it again when you stop it. Perl does the same when you |
449 |
add/remove callbacks to %SIG, so watch out. |
450 |
|
451 |
You can have as many signal watchers per signal as you want. |
452 |
|
453 |
The C<signal_ns> variant doesn't start (activate) the newly created watcher. |
454 |
|
455 |
=item $w->set ($signal) |
456 |
|
457 |
Reconfigures the watcher, see the constructor above for details. Can be at |
458 |
any time. |
459 |
|
460 |
=item $current_signum = $w->signal |
461 |
|
462 |
=item $old_signum = $w->signal ($new_signal) |
463 |
|
464 |
Returns the previously set signal (always as a number not name) and |
465 |
optionally set a new one. |
466 |
|
467 |
|
468 |
=item $w = EV::child $pid, $callback |
469 |
|
470 |
=item $w = EV::child_ns $pid, $callback |
471 |
|
472 |
Call the callback when a status change for pid C<$pid> (or any pid |
473 |
if C<$pid> is 0) has been received. More precisely: when the process |
474 |
receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all |
475 |
changed/zombie children and call the callback. |
476 |
|
477 |
You can access both status and pid by using the C<rstatus> and C<rpid> |
478 |
methods on the watcher object. |
479 |
|
480 |
You can have as many pid watchers per pid as you want. |
481 |
|
482 |
The C<child_ns> variant doesn't start (activate) the newly created watcher. |
483 |
|
484 |
=item $w->set ($pid) |
485 |
|
486 |
Reconfigures the watcher, see the constructor above for details. Can be at |
487 |
any time. |
488 |
|
489 |
=item $current_pid = $w->pid |
490 |
|
491 |
=item $old_pid = $w->pid ($new_pid) |
492 |
|
493 |
Returns the previously set process id and optionally set a new one. |
494 |
|
495 |
=item $exit_status = $w->rstatus |
496 |
|
497 |
Return the exit/wait status (as returned by waitpid, see the waitpid entry |
498 |
in perlfunc). |
499 |
|
500 |
=item $pid = $w->rpid |
501 |
|
502 |
Return the pid of the awaited child (useful when you have installed a |
503 |
watcher for all pids). |
504 |
|
505 |
|
506 |
=item $w = EV::idle $callback |
507 |
|
508 |
=item $w = EV::idle_ns $callback |
509 |
|
510 |
Call the callback when there are no pending io, timer/periodic, signal or |
511 |
child events, i.e. when the process is idle. |
512 |
|
513 |
The process will not block as long as any idle watchers are active, and |
514 |
they will be called repeatedly until stopped. |
515 |
|
516 |
The C<idle_ns> variant doesn't start (activate) the newly created watcher. |
517 |
|
518 |
|
519 |
=item $w = EV::prepare $callback |
520 |
|
521 |
=item $w = EV::prepare_ns $callback |
522 |
|
523 |
Call the callback just before the process would block. You can still |
524 |
create/modify any watchers at this point. |
525 |
|
526 |
See the EV::check watcher, below, for explanations and an example. |
527 |
|
528 |
The C<prepare_ns> variant doesn't start (activate) the newly created watcher. |
529 |
|
530 |
|
531 |
=item $w = EV::check $callback |
532 |
|
533 |
=item $w = EV::check_ns $callback |
534 |
|
535 |
Call the callback just after the process wakes up again (after it has |
536 |
gathered events), but before any other callbacks have been invoked. |
537 |
|
538 |
This is used to integrate other event-based software into the EV |
539 |
mainloop: You register a prepare callback and in there, you create io and |
540 |
timer watchers as required by the other software. Here is a real-world |
541 |
example of integrating Net::SNMP (with some details left out): |
542 |
|
543 |
our @snmp_watcher; |
544 |
|
545 |
our $snmp_prepare = EV::prepare sub { |
546 |
# do nothing unless active |
547 |
$dispatcher->{_event_queue_h} |
548 |
or return; |
549 |
|
550 |
# make the dispatcher handle any outstanding stuff |
551 |
... not shown |
552 |
|
553 |
# create an IO watcher for each and every socket |
554 |
@snmp_watcher = ( |
555 |
(map { EV::io $_, EV::READ, sub { } } |
556 |
keys %{ $dispatcher->{_descriptors} }), |
557 |
|
558 |
EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] |
559 |
? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0), |
560 |
0, sub { }, |
561 |
); |
562 |
}; |
563 |
|
564 |
The callbacks are irrelevant (and are not even being called), the |
565 |
only purpose of those watchers is to wake up the process as soon as |
566 |
one of those events occurs (socket readable, or timer timed out). The |
567 |
corresponding EV::check watcher will then clean up: |
568 |
|
569 |
our $snmp_check = EV::check sub { |
570 |
# destroy all watchers |
571 |
@snmp_watcher = (); |
572 |
|
573 |
# make the dispatcher handle any new stuff |
574 |
... not shown |
575 |
}; |
576 |
|
577 |
The callbacks of the created watchers will not be called as the watchers |
578 |
are destroyed before this cna happen (remember EV::check gets called |
579 |
first). |
580 |
|
581 |
The C<check_ns> variant doesn't start (activate) the newly created watcher. |
582 |
|
583 |
=back |
584 |
|
585 |
=head1 THREADS |
586 |
|
587 |
Threads are not supported by this module in any way. Perl pseudo-threads |
588 |
is evil stuff and must die. As soon as Perl gains real threads I will work |
589 |
on thread support for it. |
590 |
|
591 |
=head1 FORK |
592 |
|
593 |
Most of the "improved" event delivering mechanisms of modern operating |
594 |
systems have quite a few problems with fork(2) (to put it bluntly: it is |
595 |
not supported and usually destructive). Libev makes it possible to work |
596 |
around this by having a function that recreates the kernel state after |
597 |
fork in the child. |
598 |
|
599 |
On non-win32 platforms, this module requires the pthread_atfork |
600 |
functionality to do this automatically for you. This function is quite |
601 |
buggy on most BSDs, though, so YMMV. The overhead for this is quite |
602 |
negligible, because everything the function currently does is set a flag |
603 |
that is checked only when the event loop gets used the next time, so when |
604 |
you do fork but not use EV, the overhead is minimal. |
605 |
|
606 |
On win32, there is no notion of fork so all this doesn't apply, of course. |
607 |
|
608 |
=cut |
609 |
|
610 |
our $DIED = sub { |
611 |
warn "EV: error in callback (ignoring): $@"; |
612 |
}; |
613 |
|
614 |
default_loop |
615 |
or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; |
616 |
|
617 |
1; |
618 |
|
619 |
=head1 SEE ALSO |
620 |
|
621 |
L<EV::DNS>. |
622 |
|
623 |
=head1 AUTHOR |
624 |
|
625 |
Marc Lehmann <schmorp@schmorp.de> |
626 |
http://home.schmorp.de/ |
627 |
|
628 |
=cut |
629 |
|