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1NAME 1NAME
2 EV - perl interface to libev, a high performance full-featured event 2 EV - perl interface to libev, a high performance full-featured event
3 loop 3 loop
4 4
5SYNOPSIS 5SYNOPSIS
6 use EV; 6 use EV;
7
8 # TIMERS
9
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
7 38
8 # TIMERS 39 my $w = EV::child 666, 0, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
9 43
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES 44 # STAT CHANGES
38 45 my $w = EV::stat "/etc/passwd", 10, sub {
39 my $w = EV::child 666, sub {
40 my ($w, $revents) = @_; 46 my ($w, $revents) = @_;
41 my $status = $w->rstatus; 47 warn $w->path, " has changed somehow.\n";
42 }; 48 };
43 49
44 # MAINLOOP 50 # MAINLOOP
45 EV::loop; # loop until EV::unloop is called or all watchers stop 51 EV::run; # loop until EV::break is called or all watchers stop
46 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 52 EV::run EV::RUN_ONCE; # block until at least one event could be handled
47 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 53 EV::run EV::RUN_NOWAIT; # try to handle same events, but do not block
54
55BEFORE YOU START USING THIS MODULE
56 If you only need timer, I/O, signal, child and idle watchers and not the
57 advanced functionality of this module, consider using AnyEvent instead,
58 specifically the simplified API described in AE.
59
60 When used with EV as backend, the AE API is as fast as the native EV
61 API, but your programs/modules will still run with many other event
62 loops.
48 63
49DESCRIPTION 64DESCRIPTION
50 This module provides an interface to libev 65 This module provides an interface to libev
51 (<http://software.schmorp.de/pkg/libev.html>). 66 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
67 below is comprehensive, one might also consult the documentation of
68 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
69 perldoc EV::libev) for more subtle details on watcher semantics or some
70 discussion on the available backends, or how to force a specific backend
71 with "LIBEV_FLAGS", or just about in any case because it has much more
72 detailed information.
73
74 This module is very fast and scalable. It is actually so fast that you
75 can use it through the AnyEvent module, stay portable to other event
76 loops (if you don't rely on any watcher types not available through it)
77 and still be faster than with any other event loop currently supported
78 in Perl.
79
80 PORTING FROM EV 3.X to 4.X
81 EV version 4 introduces a number of incompatible changes summarised
82 here. According to the depreciation strategy used by libev, there is a
83 compatibility layer in place so programs should continue to run
84 unchanged (the XS interface lacks this layer, so programs using that one
85 need to be updated).
86
87 This compatibility layer will be switched off in some future release.
88
89 All changes relevant to Perl are renames of symbols, functions and
90 methods:
91
92 EV::loop => EV::run
93 EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
94 EV::LOOP_ONESHOT => EV::RUN_ONCE
95
96 EV::unloop => EV::break
97 EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
98 EV::UNLOOP_ONE => EV::BREAK_ONE
99 EV::UNLOOP_ALL => EV::BREAK_ALL
100
101 EV::TIMEOUT => EV::TIMER
102
103 EV::loop_count => EV::iteration
104 EV::loop_depth => EV::depth
105 EV::loop_verify => EV::verify
106
107 The loop object methods corresponding to the functions above have been
108 similarly renamed.
109
110 MODULE EXPORTS
111 This module does not export any symbols.
112
113EVENT LOOPS
114 EV supports multiple event loops: There is a single "default event loop"
115 that can handle everything including signals and child watchers, and any
116 number of "dynamic event loops" that can use different backends (with
117 various limitations), but no child and signal watchers.
118
119 You do not have to do anything to create the default event loop: When
120 the module is loaded a suitable backend is selected on the premise of
121 selecting a working backend (which for example rules out kqueue on most
122 BSDs). Modules should, unless they have "special needs" always use the
123 default loop as this is fastest (perl-wise), best supported by other
124 modules (e.g. AnyEvent or Coro) and most portable event loop.
125
126 For specific programs you can create additional event loops dynamically.
127
128 If you want to take advantage of kqueue (which often works properly for
129 sockets only) even though the default loop doesn't enable it, you can
130 *embed* a kqueue loop into the default loop: running the default loop
131 will then also service the kqueue loop to some extent. See the example
132 in the section about embed watchers for an example on how to achieve
133 that.
134
135 $loop = new EV::Loop [$flags]
136 Create a new event loop as per the specified flags. Please refer to
137 the "ev_loop_new ()" function description in the libev documentation
138 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
139 ONS>, or locally-installed as EV::libev manpage) for more info.
140
141 The loop will automatically be destroyed when it is no longer
142 referenced by any watcher and the loop object goes out of scope.
143
144 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
145 is recommended, as only the default event loop is protected by this
146 module. If you *are* embedding this loop in the default loop, this
147 is not necessary, as "EV::embed" automatically does the right thing
148 on fork.
149
150 $loop->loop_fork
151 Must be called after a fork in the child, before entering or
152 continuing the event loop. An alternative is to use
153 "EV::FLAG_FORKCHECK" which calls this function automatically, at
154 some performance loss (refer to the libev documentation).
155
156 $loop->verify
157 Calls "ev_verify" to make internal consistency checks (for debugging
158 libev) and abort the program if any data structures were found to be
159 corrupted.
160
161 $loop = EV::default_loop [$flags]
162 Return the default loop (which is a singleton object). Since this
163 module already creates the default loop with default flags,
164 specifying flags here will not have any effect unless you destroy
165 the default loop first, which isn't supported. So in short: don't do
166 it, and if you break it, you get to keep the pieces.
52 167
53BASIC INTERFACE 168BASIC INTERFACE
54 $EV::DIED 169 $EV::DIED
55 Must contain a reference to a function that is called when a 170 Must contain a reference to a function that is called when a
56 callback throws an exception (with $@ containing thr error). The 171 callback throws an exception (with $@ containing the error). The
57 default prints an informative message and continues. 172 default prints an informative message and continues.
58 173
59 If this callback throws an exception it will be silently ignored. 174 If this callback throws an exception it will be silently ignored.
175
176 $flags = EV::supported_backends
177 $flags = EV::recommended_backends
178 $flags = EV::embeddable_backends
179 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
180 this instance of EV, the set of recommended backends (supposed to be
181 good) for this platform and the set of embeddable backends (see
182 EMBED WATCHERS).
183
184 EV::sleep $seconds
185 Block the process for the given number of (fractional) seconds.
60 186
61 $time = EV::time 187 $time = EV::time
62 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
63 189
64 $time = EV::now 190 $time = EV::now
191 $time = $loop->now
65 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
66 This is the time that (relative) timers are based on, and refering 193 This is the time that (relative) timers are based on, and referring
67 to it is usually faster then calling EV::time. 194 to it is usually faster then calling EV::time.
68 195
69 $method = EV::method 196 EV::now_update
197 $loop->now_update
198 Establishes the current time by querying the kernel, updating the
199 time returned by "EV::now" in the progress. This is a costly
200 operation and is usually done automatically within "EV::run".
201
202 This function is rarely useful, but when some event callback runs
203 for a very long time without entering the event loop, updating
204 libev's idea of the current time is a good idea.
205
206 EV::suspend
207 $loop->suspend
208 EV::resume
209 $loop->resume
210 These two functions suspend and resume a loop, for use when the loop
211 is not used for a while and timeouts should not be processed.
212
213 A typical use case would be an interactive program such as a game:
214 When the user presses "^Z" to suspend the game and resumes it an
215 hour later it would be best to handle timeouts as if no time had
216 actually passed while the program was suspended. This can be
217 achieved by calling "suspend" in your "SIGTSTP" handler, sending
218 yourself a "SIGSTOP" and calling "resume" directly afterwards to
219 resume timer processing.
220
221 Effectively, all "timer" watchers will be delayed by the time spend
222 between "suspend" and "resume", and all "periodic" watchers will be
223 rescheduled (that is, they will lose any events that would have
224 occured while suspended).
225
226 After calling "suspend" you must not call *any* function on the
227 given loop other than "resume", and you must not call "resume"
228 without a previous call to "suspend".
229
230 Calling "suspend"/"resume" has the side effect of updating the event
231 loop time (see "now_update").
232
233 $backend = EV::backend
234 $backend = $loop->backend
70 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
71 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
72 237
73 EV::loop [$flags] 238 $active = EV::run [$flags]
239 $active = $loop->run ([$flags])
74 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
75 callback calls EV::unloop. 241 callback calls EV::break or the flags are nonzero (in which case the
242 return value is true) or when there are no active watchers which
243 reference the loop (keepalive is true), in which case the return
244 value will be false. The return value can generally be interpreted
245 as "if true, there is more work left to do".
76 246
77 The $flags argument can be one of the following: 247 The $flags argument can be one of the following:
78 248
79 0 as above 249 0 as above
80 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 250 EV::RUN_ONCE block at most once (wait, but do not loop)
81 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 251 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
82 252
83 EV::unloop [$how] 253 EV::break [$how]
254 $loop->break ([$how])
84 When called with no arguments or an argument of EV::UNLOOP_ONE, 255 When called with no arguments or an argument of EV::BREAK_ONE, makes
85 makes the innermost call to EV::loop return. 256 the innermost call to EV::run return.
86 257
87 When called with an argument of EV::UNLOOP_ALL, all calls to 258 When called with an argument of EV::BREAK_ALL, all calls to EV::run
88 EV::loop will return as fast as possible. 259 will return as fast as possible.
89 260
90 WATCHER 261 When called with an argument of EV::BREAK_CANCEL, any pending break
262 will be cancelled.
263
264 $count = EV::iteration
265 $count = $loop->iteration
266 Return the number of times the event loop has polled for new events.
267 Sometimes useful as a generation counter.
268
269 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
270 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
271 This function rolls together an I/O and a timer watcher for a single
272 one-shot event without the need for managing a watcher object.
273
274 If $fh_or_undef is a filehandle or file descriptor, then $events
275 must be a bitset containing either "EV::READ", "EV::WRITE" or
276 "EV::READ | EV::WRITE", indicating the type of I/O event you want to
277 wait for. If you do not want to wait for some I/O event, specify
278 "undef" for $fh_or_undef and 0 for $events).
279
280 If timeout is "undef" or negative, then there will be no timeout.
281 Otherwise an "EV::timer" with this value will be started.
282
283 When an error occurs or either the timeout or I/O watcher triggers,
284 then the callback will be called with the received event set (in
285 general you can expect it to be a combination of "EV::ERROR",
286 "EV::READ", "EV::WRITE" and "EV::TIMER").
287
288 EV::once doesn't return anything: the watchers stay active till
289 either of them triggers, then they will be stopped and freed, and
290 the callback invoked.
291
292 EV::feed_fd_event $fd, $revents
293 $loop->feed_fd_event ($fd, $revents)
294 Feed an event on a file descriptor into EV. EV will react to this
295 call as if the readyness notifications specified by $revents (a
296 combination of "EV::READ" and "EV::WRITE") happened on the file
297 descriptor $fd.
298
299 EV::feed_signal_event $signal
300 Feed a signal event into the default loop. EV will react to this
301 call as if the signal specified by $signal had occured.
302
303 EV::feed_signal $signal
304 Feed a signal event into EV - unlike "EV::feed_signal_event", this
305 works regardless of which loop has registered the signal, and is
306 mainly useful for custom signal implementations.
307
308 EV::set_io_collect_interval $time
309 $loop->set_io_collect_interval ($time)
310 EV::set_timeout_collect_interval $time
311 $loop->set_timeout_collect_interval ($time)
312 These advanced functions set the minimum block interval when polling
313 for I/O events and the minimum wait interval for timer events. See
314 the libev documentation at
315 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
316 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
317 detailed discussion.
318
319 $count = EV::pending_count
320 $count = $loop->pending_count
321 Returns the number of currently pending watchers.
322
323 EV::invoke_pending
324 $loop->invoke_pending
325 Invoke all currently pending watchers.
326
327WATCHER OBJECTS
91 A watcher is an object that gets created to record your interest in some 328 A watcher is an object that gets created to record your interest in some
92 event. For instance, if you want to wait for STDIN to become readable, 329 event. For instance, if you want to wait for STDIN to become readable,
93 you would create an EV::io watcher for that: 330 you would create an EV::io watcher for that:
94 331
95 my $watcher = EV::io *STDIN, EV::READ, sub { 332 my $watcher = EV::io *STDIN, EV::READ, sub {
96 my ($watcher, $revents) = @_; 333 my ($watcher, $revents) = @_;
97 warn "yeah, STDIN should not be readable without blocking!\n" 334 warn "yeah, STDIN should now be readable without blocking!\n"
98 }; 335 };
99 336
100 All watchers can be active (waiting for events) or inactive (paused). 337 All watchers can be active (waiting for events) or inactive (paused).
101 Only active watchers will have their callbacks invoked. All callbacks 338 Only active watchers will have their callbacks invoked. All callbacks
102 will be called with at least two arguments: the watcher and a bitmask of 339 will be called with at least two arguments: the watcher and a bitmask of
103 received events. 340 received events.
104 341
105 Each watcher type has its associated bit in revents, so you can use the 342 Each watcher type has its associated bit in revents, so you can use the
106 same callback for multiple watchers. The event mask is named after the 343 same callback for multiple watchers. The event mask is named after the
107 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 344 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
108 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 345 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
109 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 346 events (which can set both EV::READ and EV::WRITE bits).
110 (which uses EV::TIMEOUT).
111 347
112 In the rare case where one wants to create a watcher but not start it at 348 In the rare case where one wants to create a watcher but not start it at
113 the same time, each constructor has a variant with a trailing "_ns" in 349 the same time, each constructor has a variant with a trailing "_ns" in
114 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 350 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
115 351
… …
119 355
120 Also, all methods changing some aspect of a watcher (->set, ->priority, 356 Also, all methods changing some aspect of a watcher (->set, ->priority,
121 ->fh and so on) automatically stop and start it again if it is active, 357 ->fh and so on) automatically stop and start it again if it is active,
122 which means pending events get lost. 358 which means pending events get lost.
123 359
124 WATCHER TYPES 360 COMMON WATCHER METHODS
125 Now lets move to the existing watcher types and asociated methods. 361 This section lists methods common to all watchers.
126
127 The following methods are available for all watchers. Then followes a
128 description of each watcher constructor (EV::io, EV::timer,
129 EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and
130 EV::check), followed by any type-specific methods (if any).
131 362
132 $w->start 363 $w->start
133 Starts a watcher if it isn't active already. Does nothing to an 364 Starts a watcher if it isn't active already. Does nothing to an
134 already active watcher. By default, all watchers start out in the 365 already active watcher. By default, all watchers start out in the
135 active state (see the description of the "_ns" variants if you need 366 active state (see the description of the "_ns" variants if you need
136 stopped watchers). 367 stopped watchers).
137 368
138 $w->stop 369 $w->stop
139 Stop a watcher if it is active. Also clear any pending events 370 Stop a watcher if it is active. Also clear any pending events
140 (events that have been received but that didn't yet result in a 371 (events that have been received but that didn't yet result in a
141 callback invocation), regardless of wether the watcher was active or 372 callback invocation), regardless of whether the watcher was active
142 not. 373 or not.
143 374
144 $bool = $w->is_active 375 $bool = $w->is_active
145 Returns true if the watcher is active, false otherwise. 376 Returns true if the watcher is active, false otherwise.
146 377
147 $current_data = $w->data 378 $current_data = $w->data
… …
165 Pending watchers with higher priority will be invoked first. The 396 Pending watchers with higher priority will be invoked first. The
166 valid range of priorities lies between EV::MAXPRI (default 2) and 397 valid range of priorities lies between EV::MAXPRI (default 2) and
167 EV::MINPRI (default -2). If the priority is outside this range it 398 EV::MINPRI (default -2). If the priority is outside this range it
168 will automatically be normalised to the nearest valid priority. 399 will automatically be normalised to the nearest valid priority.
169 400
170 The default priority of any newly-created weatcher is 0. 401 The default priority of any newly-created watcher is 0.
171 402
403 Note that the priority semantics have not yet been fleshed out and
404 are subject to almost certain change.
405
172 $w->trigger ($revents) 406 $w->invoke ($revents)
173 Call the callback *now* with the given event mask. 407 Call the callback *now* with the given event mask.
174 408
409 $w->feed_event ($revents)
410 Feed some events on this watcher into EV. EV will react to this call
411 as if the watcher had received the given $revents mask.
412
413 $revents = $w->clear_pending
414 If the watcher is pending, this function clears its pending status
415 and returns its $revents bitset (as if its callback was invoked). If
416 the watcher isn't pending it does nothing and returns 0.
417
418 $previous_state = $w->keepalive ($bool)
419 Normally, "EV::run" will return when there are no active watchers
420 (which is a "deadlock" because no progress can be made anymore).
421 This is convenient because it allows you to start your watchers (and
422 your jobs), call "EV::run" once and when it returns you know that
423 all your jobs are finished (or they forgot to register some watchers
424 for their task :).
425
426 Sometimes, however, this gets in your way, for example when the
427 module that calls "EV::run" (usually the main program) is not the
428 same module as a long-living watcher (for example a DNS client
429 module written by somebody else even). Then you might want any
430 outstanding requests to be handled, but you would not want to keep
431 "EV::run" from returning just because you happen to have this
432 long-running UDP port watcher.
433
434 In this case you can clear the keepalive status, which means that
435 even though your watcher is active, it won't keep "EV::run" from
436 returning.
437
438 The initial value for keepalive is true (enabled), and you can
439 change it any time.
440
441 Example: Register an I/O watcher for some UDP socket but do not keep
442 the event loop from running just because of that watcher.
443
444 my $udp_socket = ...
445 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
446 $udp_watcher->keepalive (0);
447
448 $loop = $w->loop
449 Return the loop that this watcher is attached to.
450
451WATCHER TYPES
452 Each of the following subsections describes a single watcher type.
453
454 I/O WATCHERS - is this file descriptor readable or writable?
175 $w = EV::io $fileno_or_fh, $eventmask, $callback 455 $w = EV::io $fileno_or_fh, $eventmask, $callback
176 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 456 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
457 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
458 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
177 As long as the returned watcher object is alive, call the $callback 459 As long as the returned watcher object is alive, call the $callback
178 when the events specified in $eventmask. 460 when at least one of events specified in $eventmask occurs.
179 461
180 The $eventmask can be one or more of these constants ORed together: 462 The $eventmask can be one or more of these constants ORed together:
181 463
182 EV::READ wait until read() wouldn't block anymore 464 EV::READ wait until read() wouldn't block anymore
183 EV::WRITE wait until write() wouldn't block anymore 465 EV::WRITE wait until write() wouldn't block anymore
… …
195 477
196 $current_eventmask = $w->events 478 $current_eventmask = $w->events
197 $old_eventmask = $w->events ($new_eventmask) 479 $old_eventmask = $w->events ($new_eventmask)
198 Returns the previously set event mask and optionally set a new one. 480 Returns the previously set event mask and optionally set a new one.
199 481
482 TIMER WATCHERS - relative and optionally repeating timeouts
200 $w = EV::timer $after, $repeat, $callback 483 $w = EV::timer $after, $repeat, $callback
201 $w = EV::timer_ns $after, $repeat, $callback 484 $w = EV::timer_ns $after, $repeat, $callback
202 Calls the callback after $after seconds. If $repeat is non-zero, the 485 $w = $loop->timer ($after, $repeat, $callback)
203 timer will be restarted (with the $repeat value as $after) after the 486 $w = $loop->timer_ns ($after, $repeat, $callback)
204 callback returns. 487 Calls the callback after $after seconds (which may be fractional or
488 negative). If $repeat is non-zero, the timer will be restarted (with
489 the $repeat value as $after) after the callback returns.
205 490
206 This means that the callback would be called roughly after $after 491 This means that the callback would be called roughly after $after
207 seconds, and then every $repeat seconds. The timer does his best not 492 seconds, and then every $repeat seconds. The timer does his best not
208 to drift, but it will not invoke the timer more often then once per 493 to drift, but it will not invoke the timer more often then once per
209 event loop iteration, and might drift in other cases. If that isn't 494 event loop iteration, and might drift in other cases. If that isn't
… …
216 the same time. 501 the same time.
217 502
218 The "timer_ns" variant doesn't start (activate) the newly created 503 The "timer_ns" variant doesn't start (activate) the newly created
219 watcher. 504 watcher.
220 505
221 $w->set ($after, $repeat) 506 $w->set ($after, $repeat = 0)
222 Reconfigures the watcher, see the constructor above for details. Can 507 Reconfigures the watcher, see the constructor above for details. Can
223 be at any time. 508 be called at any time.
224 509
225 $w->again 510 $w->again
511 $w->again ($repeat)
226 Similar to the "start" method, but has special semantics for 512 Similar to the "start" method, but has special semantics for
227 repeating timers: 513 repeating timers:
228 514
229 If the timer is active and non-repeating, it will be stopped. 515 If the timer is active and non-repeating, it will be stopped.
230 516
… …
239 This behaviour is useful when you have a timeout for some IO 525 This behaviour is useful when you have a timeout for some IO
240 operation. You create a timer object with the same value for $after 526 operation. You create a timer object with the same value for $after
241 and $repeat, and then, in the read/write watcher, run the "again" 527 and $repeat, and then, in the read/write watcher, run the "again"
242 method on the timeout. 528 method on the timeout.
243 529
530 If called with a $repeat argument, then it uses this a timer repeat
531 value.
532
533 $after = $w->remaining
534 Calculates and returns the remaining time till the timer will fire.
535
536 $repeat = $w->repeat
537 $old_repeat = $w->repeat ($new_repeat)
538 Returns the current value of the repeat attribute and optionally
539 sets a new one. Setting the new one will not restart the watcher -
540 if the watcher is active, the new repeat value is used whenever it
541 expires next.
542
543 PERIODIC WATCHERS - to cron or not to cron?
244 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 544 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
245 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 545 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
546 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
547 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
246 Similar to EV::timer, but is not based on relative timeouts but on 548 Similar to EV::timer, but is not based on relative timeouts but on
247 absolute times. Apart from creating "simple" timers that trigger 549 absolute times. Apart from creating "simple" timers that trigger
248 "at" the specified time, it can also be used for non-drifting 550 "at" the specified time, it can also be used for non-drifting
249 absolute timers and more complex, cron-like, setups that are not 551 absolute timers and more complex, cron-like, setups that are not
250 adversely affected by time jumps (i.e. when the system clock is 552 adversely affected by time jumps (i.e. when the system clock is
251 changed by explicit date -s or other means such as ntpd). It is also 553 changed by explicit date -s or other means such as ntpd). It is also
252 the most complex watcher type in EV. 554 the most complex watcher type in EV.
253 555
254 It has three distinct "modes": 556 It has three distinct "modes":
255 557
256 * absolute timer ($interval = $reschedule_cb = 0) 558 * absolute timer ($interval = $reschedule_cb = 0)
559
257 This time simply fires at the wallclock time $at and doesn't 560 This time simply fires at the wallclock time $at and doesn't
258 repeat. It will not adjust when a time jump occurs, that is, if 561 repeat. It will not adjust when a time jump occurs, that is, if
259 it is to be run at January 1st 2011 then it will run when the 562 it is to be run at January 1st 2011 then it will run when the
260 system time reaches or surpasses this time. 563 system time reaches or surpasses this time.
261 564
262 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 565 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
566
263 In this mode the watcher will always be scheduled to time out at 567 In this mode the watcher will always be scheduled to time out at
264 the next "$at + N * $interval" time (for some integer N) and 568 the next "$at + N * $interval" time (for the lowest integer N)
265 then repeat, regardless of any time jumps. 569 and then repeat, regardless of any time jumps. Note that, since
570 "N" can be negative, the first trigger can happen before $at.
266 571
267 This can be used to create timers that do not drift with respect 572 This can be used to create timers that do not drift with respect
268 to system time: 573 to system time:
269 574
270 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; 575 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
271 576
272 That doesn't mean there will always be 3600 seconds in between 577 That doesn't mean there will always be 3600 seconds in between
273 triggers, but only that the the clalback will be called when the 578 triggers, but only that the the callback will be called when the
274 system time shows a full hour (UTC). 579 system time shows a full hour (UTC).
275 580
276 Another way to think about it (for the mathematically inclined) 581 Another way to think about it (for the mathematically inclined)
277 is that EV::periodic will try to run the callback in this mode 582 is that EV::periodic will try to run the callback in this mode
278 at the next possible time where "$time = $at (mod $interval)", 583 at the next possible time where "$time = $at (mod $interval)",
279 regardless of any time jumps. 584 regardless of any time jumps.
280 585
281 * manual reschedule mode ($reschedule_cb = coderef) 586 * manual reschedule mode ($reschedule_cb = coderef)
587
282 In this mode $interval and $at are both being ignored. Instead, 588 In this mode $interval and $at are both being ignored. Instead,
283 each time the periodic watcher gets scheduled, the reschedule 589 each time the periodic watcher gets scheduled, the reschedule
284 callback ($reschedule_cb) will be called with the watcher as 590 callback ($reschedule_cb) will be called with the watcher as
285 first, and the current time as second argument. 591 first, and the current time as second argument.
286 592
287 *This callback MUST NOT stop or destroy this or any other 593 *This callback MUST NOT stop or destroy this or any other
594 periodic watcher, ever, and MUST NOT call any event loop
288 periodic watcher, ever*. If you need to stop it, return 1e30 and 595 functions or methods*. If you need to stop it, return 1e30 and
289 stop it afterwards. 596 stop it afterwards. You may create and start an "EV::prepare"
597 watcher for this task.
290 598
291 It must return the next time to trigger, based on the passed 599 It must return the next time to trigger, based on the passed
292 time value (that is, the lowest time value larger than to the 600 time value (that is, the lowest time value larger than or equal
293 second argument). It will usually be called just before the 601 to to the second argument). It will usually be called just
294 callback will be triggered, but might be called at other times, 602 before the callback will be triggered, but might be called at
295 too. 603 other times, too.
296 604
297 This can be used to create very complex timers, such as a timer 605 This can be used to create very complex timers, such as a timer
298 that triggers on each midnight, local time (actually 24 hours 606 that triggers on each midnight, local time (actually one day
299 after the last midnight, to keep the example simple. If you know 607 after the last midnight, to keep the example simple):
300 a way to do it correctly in about the same space (without
301 requiring elaborate modules), drop me a note :):
302 608
303 my $daily = EV::periodic 0, 0, sub { 609 my $daily = EV::periodic 0, 0, sub {
304 my ($w, $now) = @_; 610 my ($w, $now) = @_;
305 611
306 use Time::Local (); 612 use Time::Local ();
307 my (undef, undef, undef, $d, $m, $y) = localtime $now; 613 my (undef, undef, undef, $d, $m, $y) = localtime $now;
308 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y 614 Time::Local::timelocal_nocheck 0, 0, 0, $d + 1, $m, $y
309 }, sub { 615 }, sub {
310 print "it's midnight or likely shortly after, now\n"; 616 print "it's midnight or likely shortly after, now\n";
311 }; 617 };
312 618
313 The "periodic_ns" variant doesn't start (activate) the newly created 619 The "periodic_ns" variant doesn't start (activate) the newly created
314 watcher. 620 watcher.
315 621
316 $w->set ($at, $interval, $reschedule_cb) 622 $w->set ($at, $interval, $reschedule_cb)
317 Reconfigures the watcher, see the constructor above for details. Can 623 Reconfigures the watcher, see the constructor above for details. Can
318 be at any time. 624 be called at any time.
319 625
320 $w->again 626 $w->again
321 Simply stops and starts the watcher again. 627 Simply stops and starts the watcher again.
322 628
629 $time = $w->at
630 Return the time that the watcher is expected to trigger next.
631
632 $offset = $w->offset
633 $old_offset = $w->offset ($new_offset)
634 Returns the current value of the offset attribute and optionally
635 sets a new one. Setting the new one will not restart the watcher -
636 if the watcher is active, the new offset value is used whenever it
637 expires next.
638
639 $interval = $w->interval
640 $old_interval = $w->interval ($new_interval)
641 See above, for the interval attribute.
642
643 $reschedule_cb = $w->reschedule_cb
644 $old_reschedule_cb = $w->reschedule_cb ($new_reschedule_cb)
645 See above, for the reschedule callback.
646
647 SIGNAL WATCHERS - signal me when a signal gets signalled!
323 $w = EV::signal $signal, $callback 648 $w = EV::signal $signal, $callback
324 $w = EV::signal_ns $signal, $callback 649 $w = EV::signal_ns $signal, $callback
650 $w = $loop->signal ($signal, $callback)
651 $w = $loop->signal_ns ($signal, $callback)
325 Call the callback when $signal is received (the signal can be 652 Call the callback when $signal is received (the signal can be
326 specified by number or by name, just as with kill or %SIG). 653 specified by number or by name, just as with "kill" or %SIG).
654
655 Only one event loop can grab a given signal - attempting to grab the
656 same signal from two EV loops will crash the program immediately or
657 cause data corruption.
327 658
328 EV will grab the signal for the process (the kernel only allows one 659 EV will grab the signal for the process (the kernel only allows one
329 component to receive a signal at a time) when you start a signal 660 component to receive a signal at a time) when you start a signal
330 watcher, and removes it again when you stop it. Perl does the same 661 watcher, and removes it again when you stop it. Perl does the same
331 when you add/remove callbacks to %SIG, so watch out. 662 when you add/remove callbacks to %SIG, so watch out.
… …
335 The "signal_ns" variant doesn't start (activate) the newly created 666 The "signal_ns" variant doesn't start (activate) the newly created
336 watcher. 667 watcher.
337 668
338 $w->set ($signal) 669 $w->set ($signal)
339 Reconfigures the watcher, see the constructor above for details. Can 670 Reconfigures the watcher, see the constructor above for details. Can
340 be at any time. 671 be called at any time.
341 672
342 $current_signum = $w->signal 673 $current_signum = $w->signal
343 $old_signum = $w->signal ($new_signal) 674 $old_signum = $w->signal ($new_signal)
344 Returns the previously set signal (always as a number not name) and 675 Returns the previously set signal (always as a number not name) and
345 optionally set a new one. 676 optionally set a new one.
346 677
678 CHILD WATCHERS - watch out for process status changes
347 $w = EV::child $pid, $callback 679 $w = EV::child $pid, $trace, $callback
348 $w = EV::child_ns $pid, $callback 680 $w = EV::child_ns $pid, $trace, $callback
681 $w = $loop->child ($pid, $trace, $callback)
682 $w = $loop->child_ns ($pid, $trace, $callback)
349 Call the callback when a status change for pid $pid (or any pid if 683 Call the callback when a status change for pid $pid (or any pid if
350 $pid is 0) has been received. More precisely: when the process 684 $pid is 0) has been received (a status change happens when the
685 process terminates or is killed, or, when trace is true,
686 additionally when it is stopped or continued). More precisely: when
351 receives a SIGCHLD, EV will fetch the outstanding exit/wait status 687 the process receives a "SIGCHLD", EV will fetch the outstanding
352 for all changed/zombie children and call the callback. 688 exit/wait status for all changed/zombie children and call the
689 callback.
353 690
354 You can access both status and pid by using the "rstatus" and "rpid" 691 It is valid (and fully supported) to install a child watcher after a
692 child has exited but before the event loop has started its next
693 iteration (for example, first you "fork", then the new child process
694 might exit, and only then do you install a child watcher in the
695 parent for the new pid).
696
697 You can access both exit (or tracing) status and pid by using the
355 methods on the watcher object. 698 "rstatus" and "rpid" methods on the watcher object.
356 699
357 You can have as many pid watchers per pid as you want. 700 You can have as many pid watchers per pid as you want, they will all
701 be called.
358 702
359 The "child_ns" variant doesn't start (activate) the newly created 703 The "child_ns" variant doesn't start (activate) the newly created
360 watcher. 704 watcher.
361 705
362 $w->set ($pid) 706 $w->set ($pid, $trace)
363 Reconfigures the watcher, see the constructor above for details. Can 707 Reconfigures the watcher, see the constructor above for details. Can
364 be at any time. 708 be called at any time.
365 709
366 $current_pid = $w->pid 710 $current_pid = $w->pid
367 $old_pid = $w->pid ($new_pid)
368 Returns the previously set process id and optionally set a new one. 711 Returns the previously set process id and optionally set a new one.
369 712
370 $exit_status = $w->rstatus 713 $exit_status = $w->rstatus
371 Return the exit/wait status (as returned by waitpid, see the waitpid 714 Return the exit/wait status (as returned by waitpid, see the waitpid
372 entry in perlfunc). 715 entry in perlfunc).
373 716
374 $pid = $w->rpid 717 $pid = $w->rpid
375 Return the pid of the awaited child (useful when you have installed 718 Return the pid of the awaited child (useful when you have installed
376 a watcher for all pids). 719 a watcher for all pids).
377 720
721 EV::Child::reinit [EXPERIMENTAL]
722 Internally, libev installs a signal handler for "SIGCHLD".
723 Unfortunately, a lot of Perl code does soemthing like "local
724 $SIG{CHLD}", which, unfortunately, is broken and will not restore
725 the signal handler.
726
727 If this has happened, you can call this function to stop/rrestart
728 the internal libev watcher, which will reset the signal handler.
729
730 Note that this is an experimental function, whose interface might
731 change.
732
733 STAT WATCHERS - did the file attributes just change?
734 $w = EV::stat $path, $interval, $callback
735 $w = EV::stat_ns $path, $interval, $callback
736 $w = $loop->stat ($path, $interval, $callback)
737 $w = $loop->stat_ns ($path, $interval, $callback)
738 Call the callback when a file status change has been detected on
739 $path. The $path does not need to exist, changing from "path exists"
740 to "path does not exist" is a status change like any other.
741
742 The $interval is a recommended polling interval for systems where
743 OS-supported change notifications don't exist or are not supported.
744 If you use 0 then an unspecified default is used (which is highly
745 recommended!), which is to be expected to be around five seconds
746 usually.
747
748 This watcher type is not meant for massive numbers of stat watchers,
749 as even with OS-supported change notifications, this can be
750 resource-intensive.
751
752 The "stat_ns" variant doesn't start (activate) the newly created
753 watcher.
754
755 ... = $w->stat
756 This call is very similar to the perl "stat" built-in: It stats
757 (using "lstat") the path specified in the watcher and sets perls
758 stat cache (as well as EV's idea of the current stat values) to the
759 values found.
760
761 In scalar context, a boolean is return indicating success or failure
762 of the stat. In list context, the same 13-value list as with stat is
763 returned (except that the blksize and blocks fields are not
764 reliable).
765
766 In the case of an error, errno is set to "ENOENT" (regardless of the
767 actual error value) and the "nlink" value is forced to zero (if the
768 stat was successful then nlink is guaranteed to be non-zero).
769
770 See also the next two entries for more info.
771
772 ... = $w->attr
773 Just like "$w->stat", but without the initial stat'ing: this returns
774 the values most recently detected by EV. See the next entry for more
775 info.
776
777 ... = $w->prev
778 Just like "$w->stat", but without the initial stat'ing: this returns
779 the previous set of values, before the change.
780
781 That is, when the watcher callback is invoked, "$w->prev" will be
782 set to the values found *before* a change was detected, while
783 "$w->attr" returns the values found leading to the change detection.
784 The difference (if any) between "prev" and "attr" is what triggered
785 the callback.
786
787 If you did something to the filesystem object and do not want to
788 trigger yet another change, you can call "stat" to update EV's idea
789 of what the current attributes are.
790
791 $w->set ($path, $interval)
792 Reconfigures the watcher, see the constructor above for details. Can
793 be called at any time.
794
795 $current_path = $w->path
796 $old_path = $w->path ($new_path)
797 Returns the previously set path and optionally set a new one.
798
799 $current_interval = $w->interval
800 $old_interval = $w->interval ($new_interval)
801 Returns the previously set interval and optionally set a new one.
802 Can be used to query the actual interval used.
803
804 IDLE WATCHERS - when you've got nothing better to do...
378 $w = EV::idle $callback 805 $w = EV::idle $callback
379 $w = EV::idle_ns $callback 806 $w = EV::idle_ns $callback
807 $w = $loop->idle ($callback)
808 $w = $loop->idle_ns ($callback)
380 Call the callback when there are no pending io, timer/periodic, 809 Call the callback when there are no other pending watchers of the
381 signal or child events, i.e. when the process is idle. 810 same or higher priority (excluding check, prepare and other idle
811 watchers of the same or lower priority, of course). They are called
812 idle watchers because when the watcher is the highest priority
813 pending event in the process, the process is considered to be idle
814 at that priority.
815
816 If you want a watcher that is only ever called when *no* other
817 events are outstanding you have to set the priority to "EV::MINPRI".
382 818
383 The process will not block as long as any idle watchers are active, 819 The process will not block as long as any idle watchers are active,
384 and they will be called repeatedly until stopped. 820 and they will be called repeatedly until stopped.
385 821
822 For example, if you have idle watchers at priority 0 and 1, and an
823 I/O watcher at priority 0, then the idle watcher at priority 1 and
824 the I/O watcher will always run when ready. Only when the idle
825 watcher at priority 1 is stopped and the I/O watcher at priority 0
826 is not pending with the 0-priority idle watcher be invoked.
827
386 The "idle_ns" variant doesn't start (activate) the newly created 828 The "idle_ns" variant doesn't start (activate) the newly created
387 watcher. 829 watcher.
388 830
831 PREPARE WATCHERS - customise your event loop!
389 $w = EV::prepare $callback 832 $w = EV::prepare $callback
390 $w = EV::prepare_ns $callback 833 $w = EV::prepare_ns $callback
834 $w = $loop->prepare ($callback)
835 $w = $loop->prepare_ns ($callback)
391 Call the callback just before the process would block. You can still 836 Call the callback just before the process would block. You can still
392 create/modify any watchers at this point. 837 create/modify any watchers at this point.
393 838
394 See the EV::check watcher, below, for explanations and an example. 839 See the EV::check watcher, below, for explanations and an example.
395 840
396 The "prepare_ns" variant doesn't start (activate) the newly created 841 The "prepare_ns" variant doesn't start (activate) the newly created
397 watcher. 842 watcher.
398 843
844 CHECK WATCHERS - customise your event loop even more!
399 $w = EV::check $callback 845 $w = EV::check $callback
400 $w = EV::check_ns $callback 846 $w = EV::check_ns $callback
847 $w = $loop->check ($callback)
848 $w = $loop->check_ns ($callback)
401 Call the callback just after the process wakes up again (after it 849 Call the callback just after the process wakes up again (after it
402 has gathered events), but before any other callbacks have been 850 has gathered events), but before any other callbacks have been
403 invoked. 851 invoked.
404 852
405 This is used to integrate other event-based software into the EV 853 This can be used to integrate other event-based software into the EV
406 mainloop: You register a prepare callback and in there, you create 854 mainloop: You register a prepare callback and in there, you create
407 io and timer watchers as required by the other software. Here is a 855 io and timer watchers as required by the other software. Here is a
408 real-world example of integrating Net::SNMP (with some details left 856 real-world example of integrating Net::SNMP (with some details left
409 out): 857 out):
410 858
… …
414 # do nothing unless active 862 # do nothing unless active
415 $dispatcher->{_event_queue_h} 863 $dispatcher->{_event_queue_h}
416 or return; 864 or return;
417 865
418 # make the dispatcher handle any outstanding stuff 866 # make the dispatcher handle any outstanding stuff
867 ... not shown
419 868
420 # create an IO watcher for each and every socket 869 # create an I/O watcher for each and every socket
421 @snmp_watcher = ( 870 @snmp_watcher = (
422 (map { EV::io $_, EV::READ, sub { } } 871 (map { EV::io $_, EV::READ, sub { } }
423 keys %{ $dispatcher->{_descriptors} }), 872 keys %{ $dispatcher->{_descriptors} }),
873
874 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
875 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
876 0, sub { },
424 ); 877 );
425
426 # if there are any timeouts, also create a timer
427 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
428 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
429 }; 878 };
430 879
431 The callbacks are irrelevant, the only purpose of those watchers is 880 The callbacks are irrelevant (and are not even being called), the
432 to wake up the process as soon as one of those events occurs (socket 881 only purpose of those watchers is to wake up the process as soon as
433 readable, or timer timed out). The corresponding EV::check watcher 882 one of those events occurs (socket readable, or timer timed out).
434 will then clean up: 883 The corresponding EV::check watcher will then clean up:
435 884
436 our $snmp_check = EV::check sub { 885 our $snmp_check = EV::check sub {
437 # destroy all watchers 886 # destroy all watchers
438 @snmp_watcher = (); 887 @snmp_watcher = ();
439 888
440 # make the dispatcher handle any new stuff 889 # make the dispatcher handle any new stuff
890 ... not shown
441 }; 891 };
442 892
443 The callbacks of the created watchers will not be called as the 893 The callbacks of the created watchers will not be called as the
444 watchers are destroyed before this cna happen (remember EV::check 894 watchers are destroyed before this can happen (remember EV::check
445 gets called first). 895 gets called first).
446 896
447 The "check_ns" variant doesn't start (activate) the newly created 897 The "check_ns" variant doesn't start (activate) the newly created
448 watcher. 898 watcher.
449 899
900 EV::CHECK constant issues
901 Like all other watcher types, there is a bitmask constant for use in
902 $revents and other places. The "EV::CHECK" is special as it has the
903 same name as the "CHECK" sub called by Perl. This doesn't cause big
904 issues on newer perls (beginning with 5.8.9), but it means thatthe
905 constant must be *inlined*, i.e. runtime calls will not work. That
906 means that as long as you always "use EV" and then "EV::CHECK" you
907 are on the safe side.
908
909 FORK WATCHERS - the audacity to resume the event loop after a fork
910 Fork watchers are called when a "fork ()" was detected. The invocation
911 is done before the event loop blocks next and before "check" watchers
912 are being called, and only in the child after the fork.
913
914 $w = EV::fork $callback
915 $w = EV::fork_ns $callback
916 $w = $loop->fork ($callback)
917 $w = $loop->fork_ns ($callback)
918 Call the callback before the event loop is resumed in the child
919 process after a fork.
920
921 The "fork_ns" variant doesn't start (activate) the newly created
922 watcher.
923
924 EMBED WATCHERS - when one backend isn't enough...
925 This is a rather advanced watcher type that lets you embed one event
926 loop into another (currently only IO events are supported in the
927 embedded loop, other types of watchers might be handled in a delayed or
928 incorrect fashion and must not be used).
929
930 See the libev documentation at
931 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
932 _when_one_backend_> (locally installed as EV::libev) for more details.
933
934 In short, this watcher is most useful on BSD systems without working
935 kqueue to still be able to handle a large number of sockets:
936
937 my $socket_loop;
938
939 # check wether we use SELECT or POLL _and_ KQUEUE is supported
940 if (
941 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
942 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
943 ) {
944 # use kqueue for sockets
945 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
946 }
947
948 # use the default loop otherwise
949 $socket_loop ||= EV::default_loop;
950
951 $w = EV::embed $otherloop[, $callback]
952 $w = EV::embed_ns $otherloop[, $callback]
953 $w = $loop->embed ($otherloop[, $callback])
954 $w = $loop->embed_ns ($otherloop[, $callback])
955 Call the callback when the embedded event loop ($otherloop) has any
956 I/O activity. The $callback is optional: if it is missing, then the
957 embedded event loop will be managed automatically (which is
958 recommended), otherwise you have to invoke "sweep" yourself.
959
960 The "embed_ns" variant doesn't start (activate) the newly created
961 watcher.
962
963 ASYNC WATCHERS - how to wake up another event loop
964 Async watchers are provided by EV, but have little use in perl directly,
965 as perl neither supports threads running in parallel nor direct access
966 to signal handlers or other contexts where they could be of value.
967
968 It is, however, possible to use them from the XS level.
969
970 Please see the libev documentation for further details.
971
972 $w = EV::async $callback
973 $w = EV::async_ns $callback
974 $w = $loop->async ($callback)
975 $w = $loop->async_ns ($callback)
976 $w->send
977 $bool = $w->async_pending
978
979 CLEANUP WATCHERS - how to clean up when the event loop goes away
980 Cleanup watchers are not supported on the Perl level, they can only be
981 used via XS currently.
982
983PERL SIGNALS
984 While Perl signal handling (%SIG) is not affected by EV, the behaviour
985 with EV is as the same as any other C library: Perl-signals will only be
986 handled when Perl runs, which means your signal handler might be invoked
987 only the next time an event callback is invoked.
988
989 The solution is to use EV signal watchers (see "EV::signal"), which will
990 ensure proper operations with regards to other event watchers.
991
992 If you cannot do this for whatever reason, you can also force a watcher
993 to be called on every event loop iteration by installing a "EV::check"
994 watcher:
995
996 my $async_check = EV::check sub { };
997
998 This ensures that perl gets into control for a short time to handle any
999 pending signals, and also ensures (slightly) slower overall operation.
1000
450THREADS 1001ITHREADS
451 Threads are not supported by this in any way. Perl pseudo-threads is 1002 Ithreads are not supported by this module in any way. Perl
452 evil stuff and must die. 1003 pseudo-threads is evil stuff and must die. Real threads as provided by
1004 Coro are fully supported (and enhanced support is available via
1005 Coro::EV).
1006
1007FORK
1008 Most of the "improved" event delivering mechanisms of modern operating
1009 systems have quite a few problems with fork(2) (to put it bluntly: it is
1010 not supported and usually destructive). Libev makes it possible to work
1011 around this by having a function that recreates the kernel state after
1012 fork in the child.
1013
1014 On non-win32 platforms, this module requires the pthread_atfork
1015 functionality to do this automatically for you. This function is quite
1016 buggy on most BSDs, though, so YMMV. The overhead for this is quite
1017 negligible, because everything the function currently does is set a flag
1018 that is checked only when the event loop gets used the next time, so
1019 when you do fork but not use EV, the overhead is minimal.
1020
1021 On win32, there is no notion of fork so all this doesn't apply, of
1022 course.
453 1023
454SEE ALSO 1024SEE ALSO
455 L<EV::DNS>. 1025 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
1026 DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed
1027 Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV
1028 (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event
1029 driven programming.
456 1030
457AUTHOR 1031AUTHOR
458 Marc Lehmann <schmorp@schmorp.de> 1032 Marc Lehmann <schmorp@schmorp.de>
459 http://home.schmorp.de/ 1033 http://home.schmorp.de/
460 1034

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