1 |
=head1 NAME |
2 |
|
3 |
EV - perl interface to libev, a high performance full-featured event loop |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
7 |
use EV; |
8 |
|
9 |
# TIMERS |
10 |
|
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my $w = EV::timer 2, 0, sub { |
12 |
warn "is called after 2s"; |
13 |
}; |
14 |
|
15 |
my $w = EV::timer 2, 2, sub { |
16 |
warn "is called roughly every 2s (repeat = 2)"; |
17 |
}; |
18 |
|
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undef $w; # destroy event watcher again |
20 |
|
21 |
my $w = EV::periodic 0, 60, 0, sub { |
22 |
warn "is called every minute, on the minute, exactly"; |
23 |
}; |
24 |
|
25 |
# IO |
26 |
|
27 |
my $w = EV::io *STDIN, EV::READ, sub { |
28 |
my ($w, $revents) = @_; # all callbacks receive the watcher and event mask |
29 |
warn "stdin is readable, you entered: ", <STDIN>; |
30 |
}; |
31 |
|
32 |
# SIGNALS |
33 |
|
34 |
my $w = EV::signal 'QUIT', sub { |
35 |
warn "sigquit received\n"; |
36 |
}; |
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|
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# CHILD/PID STATUS CHANGES |
39 |
|
40 |
my $w = EV::child 666, sub { |
41 |
my ($w, $revents) = @_; |
42 |
my $status = $w->rstatus; |
43 |
}; |
44 |
|
45 |
# MAINLOOP |
46 |
EV::loop; # loop until EV::loop_done is called or all watchers stop |
47 |
EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
48 |
EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
49 |
|
50 |
=head1 DESCRIPTION |
51 |
|
52 |
This module provides an interface to libev |
53 |
(L<http://software.schmorp.de/pkg/libev.html>). |
54 |
|
55 |
=cut |
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|
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package EV; |
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|
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use strict; |
60 |
|
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BEGIN { |
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our $VERSION = '0.8'; |
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use XSLoader; |
64 |
XSLoader::load "EV", $VERSION; |
65 |
} |
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|
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@EV::Io::ISA = |
68 |
@EV::Timer::ISA = |
69 |
@EV::Periodic::ISA = |
70 |
@EV::Signal::ISA = |
71 |
@EV::Idle::ISA = |
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@EV::Prepare::ISA = |
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@EV::Check::ISA = |
74 |
@EV::Child::ISA = "EV::Watcher"; |
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|
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=head1 BASIC INTERFACE |
77 |
|
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=over 4 |
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|
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=item $EV::DIED |
81 |
|
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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. |
85 |
|
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If this callback throws an exception it will be silently ignored. |
87 |
|
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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 |
93 |
|
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Returns the time the last event loop iteration has been started. This |
95 |
is the time that (relative) timers are based on, and refering to it is |
96 |
usually faster then calling EV::time. |
97 |
|
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=item $method = EV::ev_method |
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|
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Returns an integer describing the backend used by libev (EV::METHOD_SELECT |
101 |
or EV::METHOD_EPOLL). |
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|
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=item EV::loop [$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::loop_done. |
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|
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The $flags argument can be one of the following: |
109 |
|
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0 as above |
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EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
112 |
EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
113 |
|
114 |
=item EV::loop_done [$how] |
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|
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When called with no arguments or an argument of 1, makes the innermost |
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call to EV::loop return. |
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|
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When called with an agrument of 2, all calls to EV::loop will return as |
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fast as possible. |
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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 |
127 |
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: |
129 |
|
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my $watcher = EV::io *STDIN, EV::READ, sub { |
131 |
my ($watcher, $revents) = @_; |
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warn "yeah, STDIN should not be readable without blocking!\n" |
133 |
}; |
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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 |
138 |
events. |
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|
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Each watcher type has its associated bit in revents, so you can use the |
141 |
same callback for multiple watchers. The event mask is named after the |
142 |
type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
143 |
EV::periodic sets EV::PERIODIC and so on, with the exception of IO events |
144 |
(which can set both EV::READ and EV::WRITE bits), and EV::timer (which |
145 |
uses EV::TIMEOUT). |
146 |
|
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In the rare case where one wants to create a watcher but not start it at |
148 |
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, |
156 |
->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 |
160 |
|
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Now lets move to the existing watcher types and asociated methods. |
162 |
|
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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, |
165 |
EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by |
166 |
any type-specific methods (if any). |
167 |
|
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=over 4 |
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|
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=item $w->start |
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|
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Starts a watcher if it isn't active already. Does nothing to an already |
173 |
active watcher. By default, all watchers start out in the active state |
174 |
(see the description of the C<_ns> variants if you need stopped watchers). |
175 |
|
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=item $w->stop |
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|
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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. |
181 |
|
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=item $bool = $w->is_active |
183 |
|
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Returns true if the watcher is active, false otherwise. |
185 |
|
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=item $current_data = $w->data |
187 |
|
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=item $old_data = $w->data ($new_data) |
189 |
|
190 |
Queries a freely usable data scalar on the watcher and optionally changes |
191 |
it. This is a way to associate custom data with a watcher: |
192 |
|
193 |
my $w = EV::timer 60, 0, sub { |
194 |
warn $_[0]->data; |
195 |
}; |
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$w->data ("print me!"); |
197 |
|
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=item $current_cb = $w->cb |
199 |
|
200 |
=item $old_cb = $w->cb ($new_cb) |
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|
202 |
Queries the callback on the watcher and optionally changes it. You can do |
203 |
this at any time without the watcher restarting. |
204 |
|
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=item $current_priority = $w->priority |
206 |
|
207 |
=item $old_priority = $w->priority ($new_priority) |
208 |
|
209 |
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 |
211 |
priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default |
212 |
-2). If the priority is outside this range it will automatically be |
213 |
normalised to the nearest valid priority. |
214 |
|
215 |
The default priority of any newly-created weatcher is 0. |
216 |
|
217 |
=item $w->trigger ($revents) |
218 |
|
219 |
Call the callback *now* with the given event mask. |
220 |
|
221 |
|
222 |
=item $w = EV::io $fileno_or_fh, $eventmask, $callback |
223 |
|
224 |
=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
225 |
|
226 |
As long as the returned watcher object is alive, call the C<$callback> |
227 |
when the events specified in C<$eventmask>. |
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|
229 |
The $eventmask can be one or more of these constants ORed together: |
230 |
|
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EV::READ wait until read() wouldn't block anymore |
232 |
EV::WRITE wait until write() wouldn't block anymore |
233 |
|
234 |
The C<io_ns> variant doesn't start (activate) the newly created watcher. |
235 |
|
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=item $w->set ($fileno_or_fh, $eventmask) |
237 |
|
238 |
Reconfigures the watcher, see the constructor above for details. Can be |
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called at any time. |
240 |
|
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=item $current_fh = $w->fh |
242 |
|
243 |
=item $old_fh = $w->fh ($new_fh) |
244 |
|
245 |
Returns the previously set filehandle and optionally set a new one. |
246 |
|
247 |
=item $current_eventmask = $w->events |
248 |
|
249 |
=item $old_eventmask = $w->events ($new_eventmask) |
250 |
|
251 |
Returns the previously set event mask and optionally set a new one. |
252 |
|
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|
254 |
=item $w = EV::timer $after, $repeat, $callback |
255 |
|
256 |
=item $w = EV::timer_ns $after, $repeat, $callback |
257 |
|
258 |
Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, |
259 |
the timer will be restarted (with the $repeat value as $after) after the |
260 |
callback returns. |
261 |
|
262 |
This means that the callback would be called roughly after C<$after> |
263 |
seconds, and then every C<$repeat> seconds. "Roughly" because the time of |
264 |
callback processing is not taken into account, so the timer will slowly |
265 |
drift. If that isn't acceptable, look at EV::periodic. |
266 |
|
267 |
The timer is based on a monotonic clock, that is if somebody is sitting |
268 |
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. |
270 |
|
271 |
The C<timer_ns> variant doesn't start (activate) the newly created watcher. |
272 |
|
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=item $w->set ($after, $repeat) |
274 |
|
275 |
Reconfigures the watcher, see the constructor above for details. Can be at |
276 |
any time. |
277 |
|
278 |
=item $w->again |
279 |
|
280 |
Similar to the C<start> method, but has special semantics for repeating timers: |
281 |
|
282 |
If the timer is active and repeating, reset the timeout to occur |
283 |
C<$repeat> seconds after now. |
284 |
|
285 |
If the timer is active and non-repeating, it will be stopped. |
286 |
|
287 |
If the timer is in active and repeating, start it. |
288 |
|
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Otherwise do nothing. |
290 |
|
291 |
This behaviour is useful when you have a timeout for some IO |
292 |
operation. You create a timer object with the same value for C<$after> and |
293 |
C<$repeat>, and then, in the read/write watcher, run the C<again> method |
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on the timeout. |
295 |
|
296 |
|
297 |
=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
298 |
|
299 |
=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
300 |
|
301 |
Similar to EV::timer, but is not based on relative timeouts but on |
302 |
absolute times. Apart from creating "simple" timers that trigger "at" the |
303 |
specified time, it can also be used for non-drifting absolute timers and |
304 |
more complex, cron-like, setups that are not adversely affected by time |
305 |
jumps (i.e. when the system clock is changed by explicit date -s or other |
306 |
means such as ntpd). It is also the most complex watcher type in EV. |
307 |
|
308 |
It has three distinct "modes": |
309 |
|
310 |
=over 4 |
311 |
|
312 |
=item * absolute timer ($interval = $reschedule_cb = 0) |
313 |
|
314 |
This time simply fires at the wallclock time C<$at> and doesn't repeat. It |
315 |
will not adjust when a time jump occurs, that is, if it is to be run |
316 |
at January 1st 2011 then it will run when the system time reaches or |
317 |
surpasses this time. |
318 |
|
319 |
=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) |
320 |
|
321 |
In this mode the watcher will always be scheduled to time out at the |
322 |
next C<$at + N * $interval> time (for some integer N) and then repeat, |
323 |
regardless of any time jumps. |
324 |
|
325 |
This can be used to create timers that do not drift with respect to system |
326 |
time: |
327 |
|
328 |
my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; |
329 |
|
330 |
That doesn't mean there will always be 3600 seconds in between triggers, |
331 |
but only that the the clalback will be called when the system time shows a |
332 |
full hour (UTC). |
333 |
|
334 |
Another way to think about it (for the mathematically inclined) is that |
335 |
EV::periodic will try to run the callback in this mode at the next |
336 |
possible time where C<$time = $at (mod $interval)>, regardless of any time |
337 |
jumps. |
338 |
|
339 |
=item * manual reschedule mode ($reschedule_cb = coderef) |
340 |
|
341 |
In this mode $interval and $at are both being ignored. Instead, each time |
342 |
the periodic watcher gets scheduled, the first callback ($reschedule_cb) |
343 |
will be called with the watcher as first, and the current time as second |
344 |
argument. |
345 |
|
346 |
I<This callback MUST NOT stop or destroy this or any other periodic |
347 |
watcher, ever>. If you need to stop it, return 1e30 and stop it |
348 |
afterwards. |
349 |
|
350 |
It must return the next time to trigger, based on the passed time value |
351 |
(that is, the lowest time value larger than to the second argument). It |
352 |
will usually be called just before the callback will be triggered, but |
353 |
might be called at other times, too. |
354 |
|
355 |
This can be used to create very complex timers, such as a timer that |
356 |
triggers on each midnight, local time (actually 24 hours after the last |
357 |
midnight, to keep the example simple. If you know a way to do it correctly |
358 |
in about the same space (without requiring elaborate modules), drop me a |
359 |
note :): |
360 |
|
361 |
my $daily = EV::periodic 0, 0, sub { |
362 |
my ($w, $now) = @_; |
363 |
|
364 |
use Time::Local (); |
365 |
my (undef, undef, undef, $d, $m, $y) = localtime $now; |
366 |
86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y |
367 |
}, sub { |
368 |
print "it's midnight or likely shortly after, now\n"; |
369 |
}; |
370 |
|
371 |
=back |
372 |
|
373 |
The C<periodic_ns> variant doesn't start (activate) the newly created watcher. |
374 |
|
375 |
=item $w->set ($at, $interval, $reschedule_cb) |
376 |
|
377 |
Reconfigures the watcher, see the constructor above for details. Can be at |
378 |
any time. |
379 |
|
380 |
=item $w->again |
381 |
|
382 |
Simply stops and starts the watcher again. |
383 |
|
384 |
|
385 |
=item $w = EV::signal $signal, $callback |
386 |
|
387 |
=item $w = EV::signal_ns $signal, $callback |
388 |
|
389 |
Call the callback when $signal is received (the signal can be specified |
390 |
by number or by name, just as with kill or %SIG). |
391 |
|
392 |
EV will grab the signal for the process (the kernel only allows one |
393 |
component to receive a signal at a time) when you start a signal watcher, |
394 |
and removes it again when you stop it. Perl does the same when you |
395 |
add/remove callbacks to %SIG, so watch out. |
396 |
|
397 |
You can have as many signal watchers per signal as you want. |
398 |
|
399 |
The C<signal_ns> variant doesn't start (activate) the newly created watcher. |
400 |
|
401 |
=item $w->set ($signal) |
402 |
|
403 |
Reconfigures the watcher, see the constructor above for details. Can be at |
404 |
any time. |
405 |
|
406 |
=item $current_signum = $w->signal |
407 |
|
408 |
=item $old_signum = $w->signal ($new_signal) |
409 |
|
410 |
Returns the previously set signal (always as a number not name) and |
411 |
optionally set a new one. |
412 |
|
413 |
|
414 |
=item $w = EV::child $pid, $callback |
415 |
|
416 |
=item $w = EV::child_ns $pid, $callback |
417 |
|
418 |
Call the callback when a status change for pid C<$pid> (or any pid |
419 |
if C<$pid> is 0) has been received. More precisely: when the process |
420 |
receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all |
421 |
changed/zombie children and call the callback. |
422 |
|
423 |
You can access both status and pid by using the C<rstatus> and C<rpid> |
424 |
methods on the watcher object. |
425 |
|
426 |
You can have as many pid watchers per pid as you want. |
427 |
|
428 |
The C<child_ns> variant doesn't start (activate) the newly created watcher. |
429 |
|
430 |
=item $w->set ($pid) |
431 |
|
432 |
Reconfigures the watcher, see the constructor above for details. Can be at |
433 |
any time. |
434 |
|
435 |
=item $current_pid = $w->pid |
436 |
|
437 |
=item $old_pid = $w->pid ($new_pid) |
438 |
|
439 |
Returns the previously set process id and optionally set a new one. |
440 |
|
441 |
=item $exit_status = $w->rstatus |
442 |
|
443 |
Return the exit/wait status (as returned by waitpid, see the waitpid entry |
444 |
in perlfunc). |
445 |
|
446 |
=item $pid = $w->rpid |
447 |
|
448 |
Return the pid of the awaited child (useful when you have installed a |
449 |
watcher for all pids). |
450 |
|
451 |
|
452 |
=item $w = EV::idle $callback |
453 |
|
454 |
=item $w = EV::idle_ns $callback |
455 |
|
456 |
Call the callback when there are no pending io, timer/periodic, signal or |
457 |
child events, i.e. when the process is idle. |
458 |
|
459 |
The process will not block as long as any idle watchers are active, and |
460 |
they will be called repeatedly until stopped. |
461 |
|
462 |
The C<idle_ns> variant doesn't start (activate) the newly created watcher. |
463 |
|
464 |
|
465 |
=item $w = EV::prepare $callback |
466 |
|
467 |
=item $w = EV::prepare_ns $callback |
468 |
|
469 |
Call the callback just before the process would block. You can still |
470 |
create/modify any watchers at this point. |
471 |
|
472 |
See the EV::check watcher, below, for explanations and an example. |
473 |
|
474 |
The C<prepare_ns> variant doesn't start (activate) the newly created watcher. |
475 |
|
476 |
|
477 |
=item $w = EV::check $callback |
478 |
|
479 |
=item $w = EV::check_ns $callback |
480 |
|
481 |
Call the callback just after the process wakes up again (after it has |
482 |
gathered events), but before any other callbacks have been invoked. |
483 |
|
484 |
This is used to integrate other event-based software into the EV |
485 |
mainloop: You register a prepare callback and in there, you create io and |
486 |
timer watchers as required by the other software. Here is a real-world |
487 |
example of integrating Net::SNMP (with some details left out): |
488 |
|
489 |
our @snmp_watcher; |
490 |
|
491 |
our $snmp_prepare = EV::prepare sub { |
492 |
# do nothing unless active |
493 |
$dispatcher->{_event_queue_h} |
494 |
or return; |
495 |
|
496 |
# make the dispatcher handle any outstanding stuff |
497 |
|
498 |
# create an IO watcher for each and every socket |
499 |
@snmp_watcher = ( |
500 |
(map { EV::io $_, EV::READ, sub { } } |
501 |
keys %{ $dispatcher->{_descriptors} }), |
502 |
); |
503 |
|
504 |
# if there are any timeouts, also create a timer |
505 |
push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { } |
506 |
if $event->[Net::SNMP::Dispatcher::_ACTIVE]; |
507 |
}; |
508 |
|
509 |
The callbacks are irrelevant, the only purpose of those watchers is |
510 |
to wake up the process as soon as one of those events occurs (socket |
511 |
readable, or timer timed out). The corresponding EV::check watcher will then |
512 |
clean up: |
513 |
|
514 |
our $snmp_check = EV::check sub { |
515 |
# destroy all watchers |
516 |
@snmp_watcher = (); |
517 |
|
518 |
# make the dispatcher handle any new stuff |
519 |
}; |
520 |
|
521 |
The callbacks of the created watchers will not be called as the watchers |
522 |
are destroyed before this cna happen (remember EV::check gets called |
523 |
first). |
524 |
|
525 |
The C<check_ns> variant doesn't start (activate) the newly created watcher. |
526 |
|
527 |
=back |
528 |
|
529 |
=head1 THREADS |
530 |
|
531 |
Threads are not supported by this in any way. Perl pseudo-threads is evil |
532 |
stuff and must die. |
533 |
|
534 |
=cut |
535 |
|
536 |
our $DIED = sub { |
537 |
warn "EV: error in callback (ignoring): $@"; |
538 |
}; |
539 |
|
540 |
default_loop |
541 |
or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; |
542 |
|
543 |
1; |
544 |
|
545 |
=head1 SEE ALSO |
546 |
|
547 |
L<EV::DNS>, L<EV::AnyEvent>. |
548 |
|
549 |
=head1 AUTHOR |
550 |
|
551 |
Marc Lehmann <schmorp@schmorp.de> |
552 |
http://home.schmorp.de/ |
553 |
|
554 |
=cut |
555 |
|