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Revision 1.14 by root, Wed Nov 28 19:22:16 2007 UTC vs.
Revision 1.21 by root, Sat Dec 22 16:48:33 2007 UTC

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56 This module provides an interface to libev 56 This module provides an interface to libev
57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation 57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
58 below is comprehensive, one might also consult the documentation of 58 below is comprehensive, one might also consult the documentation of
59 libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle 59 libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle
60 details on watcher semantics or some discussion on the available 60 details on watcher semantics or some discussion on the available
61 backends, or how to force a specific backend with "LIBEV_FLAGS". 61 backends, or how to force a specific backend with "LIBEV_FLAGS", or just
62 about in any case because it has much more detailed information.
63
64EVENT LOOPS
65 EV supports multiple event loops: There is a single "default event loop"
66 that can handle everything including signals and child watchers, and any
67 number of "dynamic event loops" that can use different backends (with
68 various limitations), but no child and signal watchers.
69
70 You do not have to do anything to create the default event loop: When
71 the module is loaded a suitable backend is selected on the premise of
72 selecting a working backend (which for example rules out kqueue on most
73 BSDs). Modules should, unless they have "special needs" always use the
74 default loop as this is fastest (perl-wise), best supported by other
75 modules (e.g. AnyEvent or Coro) and most portable event loop.
76
77 For specific programs you can create additional event loops dynamically.
78
79 $loop = new EV::loop [$flags]
80 Create a new event loop as per the specified flags. Please refer to
81 the "ev_loop_new ()" function description in the libev documentation
82 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
83 ONS>) for more info.
84
85 The loop will automatically be destroyed when it is no longer
86 referenced by any watcher and the loop object goes out of scope.
87
88 Using "EV::FLAG_FORKCHECK" is recommended, as only the default event
89 loop is protected by this module.
90
91 $loop->loop_fork
92 Must be called after a fork in the child, before entering or
93 continuing the event loop. An alternative is to use
94 "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at
95 some performance loss (refer to the libev documentation).
96
97 $loop = EV::default_loop [$flags]
98 Return the default loop (which is a singleton object).
62 99
63BASIC INTERFACE 100BASIC INTERFACE
64 $EV::DIED 101 $EV::DIED
65 Must contain a reference to a function that is called when a 102 Must contain a reference to a function that is called when a
66 callback throws an exception (with $@ containing thr error). The 103 callback throws an exception (with $@ containing the error). The
67 default prints an informative message and continues. 104 default prints an informative message and continues.
68 105
69 If this callback throws an exception it will be silently ignored. 106 If this callback throws an exception it will be silently ignored.
107
108 $flags = EV::supported_backends
109 $flags = EV::recommended_backends
110 $flags = EV::embeddable_backends
111 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
112 this instance of EV, the set of recommended backends (supposed to be
113 good) for this platform and the set of embeddable backends (see
114 EMBED WATCHERS).
115
116 EV::sleep $seconds
117 Block the process for the given number of (fractional) seconds.
70 118
71 $time = EV::time 119 $time = EV::time
72 Returns the current time in (fractional) seconds since the epoch. 120 Returns the current time in (fractional) seconds since the epoch.
73 121
74 $time = EV::now 122 $time = EV::now
123 $time = $loop->now
75 Returns the time the last event loop iteration has been started. 124 Returns the time the last event loop iteration has been started.
76 This is the time that (relative) timers are based on, and refering 125 This is the time that (relative) timers are based on, and refering
77 to it is usually faster then calling EV::time. 126 to it is usually faster then calling EV::time.
78 127
79 $method = EV::method 128 $backend = EV::backend
129 $backend = $loop->backend
80 Returns an integer describing the backend used by libev 130 Returns an integer describing the backend used by libev
81 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 131 (EV::METHOD_SELECT or EV::METHOD_EPOLL).
82 132
83 EV::loop [$flags] 133 EV::loop [$flags]
134 $loop->loop ([$flags])
84 Begin checking for events and calling callbacks. It returns when a 135 Begin checking for events and calling callbacks. It returns when a
85 callback calls EV::unloop. 136 callback calls EV::unloop.
86 137
87 The $flags argument can be one of the following: 138 The $flags argument can be one of the following:
88 139
89 0 as above 140 0 as above
90 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 141 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
91 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 142 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
92 143
93 EV::unloop [$how] 144 EV::unloop [$how]
145 $loop->unloop ([$how])
94 When called with no arguments or an argument of EV::UNLOOP_ONE, 146 When called with no arguments or an argument of EV::UNLOOP_ONE,
95 makes the innermost call to EV::loop return. 147 makes the innermost call to EV::loop return.
96 148
97 When called with an argument of EV::UNLOOP_ALL, all calls to 149 When called with an argument of EV::UNLOOP_ALL, all calls to
98 EV::loop will return as fast as possible. 150 EV::loop will return as fast as possible.
99 151
152 $count = EV::loop_count
153 $count = $loop->loop_count
154 Return the number of times the event loop has polled for new events.
155 Sometiems useful as a generation counter.
156
100 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 157 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
158 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
101 This function rolls together an I/O and a timer watcher for a single 159 This function rolls together an I/O and a timer watcher for a single
102 one-shot event without the need for managing a watcher object. 160 one-shot event without the need for managing a watcher object.
103 161
104 If $fh_or_undef is a filehandle or file descriptor, then $events 162 If $fh_or_undef is a filehandle or file descriptor, then $events
105 must be a bitset containing either "EV::READ", "EV::WRITE" or 163 must be a bitset containing either "EV::READ", "EV::WRITE" or
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110 If timeout is "undef" or negative, then there will be no timeout. 168 If timeout is "undef" or negative, then there will be no timeout.
111 Otherwise a EV::timer with this value will be started. 169 Otherwise a EV::timer with this value will be started.
112 170
113 When an error occurs or either the timeout or I/O watcher triggers, 171 When an error occurs or either the timeout or I/O watcher triggers,
114 then the callback will be called with the received event set (in 172 then the callback will be called with the received event set (in
115 general you can expect it to be a combination of "EV:ERROR", 173 general you can expect it to be a combination of "EV::ERROR",
116 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 174 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
117 175
118 EV::once doesn't return anything: the watchers stay active till 176 EV::once doesn't return anything: the watchers stay active till
119 either of them triggers, then they will be stopped and freed, and 177 either of them triggers, then they will be stopped and freed, and
120 the callback invoked. 178 the callback invoked.
121 179
180 EV::feed_fd_event ($fd, $revents)
181 $loop->feed_fd_event ($fd, $revents)
182 Feed an event on a file descriptor into EV. EV will react to this
183 call as if the readyness notifications specified by $revents (a
184 combination of "EV::READ" and "EV::WRITE") happened on the file
185 descriptor $fd.
186
187 EV::feed_signal_event ($signal)
188 Feed a signal event into EV. EV will react to this call as if the
189 signal specified by $signal had occured.
190
191 EV::set_io_collect_interval $time
192 $loop->set_io_collect_interval ($time)
193 EV::set_timeout_collect_interval $time
194 $loop->set_timeout_collect_interval ($time)
195 These advanced functions set the minimum block interval when polling
196 for I/O events and the minimum wait interval for timer events. See
197 the libev documentation at
198 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
199 ROLLING_THE_EVENT_LOOP> for a more detailed discussion.
200
122 WATCHER OBJECTS 201WATCHER OBJECTS
123 A watcher is an object that gets created to record your interest in some 202 A watcher is an object that gets created to record your interest in some
124 event. For instance, if you want to wait for STDIN to become readable, 203 event. For instance, if you want to wait for STDIN to become readable,
125 you would create an EV::io watcher for that: 204 you would create an EV::io watcher for that:
126 205
127 my $watcher = EV::io *STDIN, EV::READ, sub { 206 my $watcher = EV::io *STDIN, EV::READ, sub {
128 my ($watcher, $revents) = @_; 207 my ($watcher, $revents) = @_;
129 warn "yeah, STDIN should not be readable without blocking!\n" 208 warn "yeah, STDIN should now be readable without blocking!\n"
130 }; 209 };
131 210
132 All watchers can be active (waiting for events) or inactive (paused). 211 All watchers can be active (waiting for events) or inactive (paused).
133 Only active watchers will have their callbacks invoked. All callbacks 212 Only active watchers will have their callbacks invoked. All callbacks
134 will be called with at least two arguments: the watcher and a bitmask of 213 will be called with at least two arguments: the watcher and a bitmask of
135 received events. 214 received events.
136 215
137 Each watcher type has its associated bit in revents, so you can use the 216 Each watcher type has its associated bit in revents, so you can use the
138 same callback for multiple watchers. The event mask is named after the 217 same callback for multiple watchers. The event mask is named after the
139 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 218 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
140 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 219 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
141 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 220 events (which can set both EV::READ and EV::WRITE bits), and EV::timer
142 (which uses EV::TIMEOUT). 221 (which uses EV::TIMEOUT).
143 222
144 In the rare case where one wants to create a watcher but not start it at 223 In the rare case where one wants to create a watcher but not start it at
145 the same time, each constructor has a variant with a trailing "_ns" in 224 the same time, each constructor has a variant with a trailing "_ns" in
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163 stopped watchers). 242 stopped watchers).
164 243
165 $w->stop 244 $w->stop
166 Stop a watcher if it is active. Also clear any pending events 245 Stop a watcher if it is active. Also clear any pending events
167 (events that have been received but that didn't yet result in a 246 (events that have been received but that didn't yet result in a
168 callback invocation), regardless of wether the watcher was active or 247 callback invocation), regardless of whether the watcher was active
169 not. 248 or not.
170 249
171 $bool = $w->is_active 250 $bool = $w->is_active
172 Returns true if the watcher is active, false otherwise. 251 Returns true if the watcher is active, false otherwise.
173 252
174 $current_data = $w->data 253 $current_data = $w->data
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197 The default priority of any newly-created watcher is 0. 276 The default priority of any newly-created watcher is 0.
198 277
199 Note that the priority semantics have not yet been fleshed out and 278 Note that the priority semantics have not yet been fleshed out and
200 are subject to almost certain change. 279 are subject to almost certain change.
201 280
202 $w->trigger ($revents) 281 $w->invoke ($revents)
203 Call the callback *now* with the given event mask. 282 Call the callback *now* with the given event mask.
283
284 $w->feed_event ($revents)
285 Feed some events on this watcher into EV. EV will react to this call
286 as if the watcher had received the given $revents mask.
287
288 $revents = $w->clear_pending
289 If the watcher is pending, this function clears its pending status
290 and returns its $revents bitset (as if its callback was invoked). If
291 the watcher isn't pending it does nothing and returns 0.
204 292
205 $previous_state = $w->keepalive ($bool) 293 $previous_state = $w->keepalive ($bool)
206 Normally, "EV::loop" will return when there are no active watchers 294 Normally, "EV::loop" will return when there are no active watchers
207 (which is a "deadlock" because no progress can be made anymore). 295 (which is a "deadlock" because no progress can be made anymore).
208 This is convinient because it allows you to start your watchers (and 296 This is convinient because it allows you to start your watchers (and
209 your jobs), call "EV::loop" once and when it returns you know that 297 your jobs), call "EV::loop" once and when it returns you know that
210 all your jobs are finished (or they forgot to register some watchers 298 all your jobs are finished (or they forgot to register some watchers
211 for their task :). 299 for their task :).
212 300
213 Sometimes, however, this gets in your way, for example when you the 301 Sometimes, however, this gets in your way, for example when the
214 module that calls "EV::loop" (usually the main program) is not the 302 module that calls "EV::loop" (usually the main program) is not the
215 same module as a long-living watcher (for example a DNS client 303 same module as a long-living watcher (for example a DNS client
216 module written by somebody else even). Then you might want any 304 module written by somebody else even). Then you might want any
217 outstanding requests to be handled, but you would not want to keep 305 outstanding requests to be handled, but you would not want to keep
218 "EV::loop" from returning just because you happen to have this 306 "EV::loop" from returning just because you happen to have this
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223 returning. 311 returning.
224 312
225 The initial value for keepalive is true (enabled), and you cna 313 The initial value for keepalive is true (enabled), and you cna
226 change it any time. 314 change it any time.
227 315
228 Example: Register an IO watcher for some UDP socket but do not keep 316 Example: Register an I/O watcher for some UDP socket but do not keep
229 the event loop from running just because of that watcher. 317 the event loop from running just because of that watcher.
230 318
231 my $udp_socket = ... 319 my $udp_socket = ...
232 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 320 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
233 $udp_watcher->keepalive (0); 321 $1000udp_watcher->keepalive (0);
234 322
323 $loop = $w->loop
324 Return the loop that this watcher is attached to.
325
235 WATCHER TYPES 326WATCHER TYPES
236 Each of the following subsections describes a single watcher type. 327 Each of the following subsections describes a single watcher type.
237 328
238 IO WATCHERS - is this file descriptor readable or writable? 329 I/O WATCHERS - is this file descriptor readable or writable?
239 $w = EV::io $fileno_or_fh, $eventmask, $callback 330 $w = EV::io $fileno_or_fh, $eventmask, $callback
240 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 331 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
332 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
333 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
241 As long as the returned watcher object is alive, call the $callback 334 As long as the returned watcher object is alive, call the $callback
242 when at least one of events specified in $eventmask occurs. 335 when at least one of events specified in $eventmask occurs.
243 336
244 The $eventmask can be one or more of these constants ORed together: 337 The $eventmask can be one or more of these constants ORed together:
245 338
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262 Returns the previously set event mask and optionally set a new one. 355 Returns the previously set event mask and optionally set a new one.
263 356
264 TIMER WATCHERS - relative and optionally repeating timeouts 357 TIMER WATCHERS - relative and optionally repeating timeouts
265 $w = EV::timer $after, $repeat, $callback 358 $w = EV::timer $after, $repeat, $callback
266 $w = EV::timer_ns $after, $repeat, $callback 359 $w = EV::timer_ns $after, $repeat, $callback
360 $w = $loop->timer ($after, $repeat, $callback)
361 $w = $loop->timer_ns ($after, $repeat, $callback)
267 Calls the callback after $after seconds (which may be fractional). 362 Calls the callback after $after seconds (which may be fractional).
268 If $repeat is non-zero, the timer will be restarted (with the 363 If $repeat is non-zero, the timer will be restarted (with the
269 $repeat value as $after) after the callback returns. 364 $repeat value as $after) after the callback returns.
270 365
271 This means that the callback would be called roughly after $after 366 This means that the callback would be called roughly after $after
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307 method on the timeout. 402 method on the timeout.
308 403
309 PERIODIC WATCHERS - to cron or not to cron? 404 PERIODIC WATCHERS - to cron or not to cron?
310 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 405 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
311 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 406 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
407 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
408 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
312 Similar to EV::timer, but is not based on relative timeouts but on 409 Similar to EV::timer, but is not based on relative timeouts but on
313 absolute times. Apart from creating "simple" timers that trigger 410 absolute times. Apart from creating "simple" timers that trigger
314 "at" the specified time, it can also be used for non-drifting 411 "at" the specified time, it can also be used for non-drifting
315 absolute timers and more complex, cron-like, setups that are not 412 absolute timers and more complex, cron-like, setups that are not
316 adversely affected by time jumps (i.e. when the system clock is 413 adversely affected by time jumps (i.e. when the system clock is
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384 be called at any time. 481 be called at any time.
385 482
386 $w->again 483 $w->again
387 Simply stops and starts the watcher again. 484 Simply stops and starts the watcher again.
388 485
486 $time = $w->at
487 Return the time that the watcher is expected to trigger next.
488
389 SIGNAL WATCHERS - signal me when a signal gets signalled! 489 SIGNAL WATCHERS - signal me when a signal gets signalled!
390 $w = EV::signal $signal, $callback 490 $w = EV::signal $signal, $callback
391 $w = EV::signal_ns $signal, $callback 491 $w = EV::signal_ns $signal, $callback
392 Call the callback when $signal is received (the signal can be 492 Call the callback when $signal is received (the signal can be
393 specified by number or by name, just as with "kill" or %SIG). 493 specified by number or by name, just as with "kill" or %SIG).
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412 optionally set a new one. 512 optionally set a new one.
413 513
414 CHILD WATCHERS - watch out for process status changes 514 CHILD WATCHERS - watch out for process status changes
415 $w = EV::child $pid, $callback 515 $w = EV::child $pid, $callback
416 $w = EV::child_ns $pid, $callback 516 $w = EV::child_ns $pid, $callback
517 $w = $loop->child ($pid, $callback)
518 $w = $loop->child_ns ($pid, $callback)
417 Call the callback when a status change for pid $pid (or any pid if 519 Call the callback when a status change for pid $pid (or any pid if
418 $pid is 0) has been received. More precisely: when the process 520 $pid is 0) has been received. More precisely: when the process
419 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 521 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status
420 for all changed/zombie children and call the callback. 522 for all changed/zombie children and call the callback.
421 523
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451 a watcher for all pids). 553 a watcher for all pids).
452 554
453 STAT WATCHERS - did the file attributes just change? 555 STAT WATCHERS - did the file attributes just change?
454 $w = EV::stat $path, $interval, $callback 556 $w = EV::stat $path, $interval, $callback
455 $w = EV::stat_ns $path, $interval, $callback 557 $w = EV::stat_ns $path, $interval, $callback
558 $w = $loop->stat ($path, $interval, $callback)
559 $w = $loop->stat_ns ($path, $interval, $callback)
456 Call the callback when a file status change has been detected on 560 Call the callback when a file status change has been detected on
457 $path. The $path does not need to exist, changing from "path exists" 561 $path. The $path does not need to exist, changing from "path exists"
458 to "path does not exist" is a status change like any other. 562 to "path does not exist" is a status change like any other.
459 563
460 The $interval is a recommended polling interval for systems where 564 The $interval is a recommended polling interval for systems where
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520 Can be used to query the actual interval used. 624 Can be used to query the actual interval used.
521 625
522 IDLE WATCHERS - when you've got nothing better to do... 626 IDLE WATCHERS - when you've got nothing better to do...
523 $w = EV::idle $callback 627 $w = EV::idle $callback
524 $w = EV::idle_ns $callback 628 $w = EV::idle_ns $callback
629 $w = $loop->idle ($callback)
630 $w = $loop->idle_ns ($callback)
525 Call the callback when there are no pending io, timer/periodic, 631 Call the callback when there are no other pending watchers of the
526 signal or child events, i.e. when the process is idle. 632 same or higher priority (excluding check, prepare and other idle
633 watchers of the same or lower priority, of course). They are called
634 idle watchers because when the watcher is the highest priority
635 pending event in the process, the process is considered to be idle
636 at that priority.
637
638 If you want a watcher that is only ever called when *no* other
639 events are outstanding you have to set the priority to "EV::MINPRI".
527 640
528 The process will not block as long as any idle watchers are active, 641 The process will not block as long as any idle watchers are active,
529 and they will be called repeatedly until stopped. 642 and they will be called repeatedly until stopped.
643
644 For example, if you have idle watchers at priority 0 and 1, and an
645 I/O watcher at priority 0, then the idle watcher at priority 1 and
646 the I/O watcher will always run when ready. Only when the idle
647 watcher at priority 1 is stopped and the I/O watcher at priority 0
648 is not pending with the 0-priority idle watcher be invoked.
530 649
531 The "idle_ns" variant doesn't start (activate) the newly created 650 The "idle_ns" variant doesn't start (activate) the newly created
532 watcher. 651 watcher.
533 652
534 PREPARE WATCHERS - customise your event loop! 653 PREPARE WATCHERS - customise your event loop!
535 $w = EV::prepare $callback 654 $w = EV::prepare $callback
536 $w = EV::prepare_ns $callback 655 $w = EV::prepare_ns $callback
656 $w = $loop->prepare ($callback)
657 $w = $loop->prepare_ns ($callback)
537 Call the callback just before the process would block. You can still 658 Call the callback just before the process would block. You can still
538 create/modify any watchers at this point. 659 create/modify any watchers at this point.
539 660
540 See the EV::check watcher, below, for explanations and an example. 661 See the EV::check watcher, below, for explanations and an example.
541 662
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543 watcher. 664 watcher.
544 665
545 CHECK WATCHERS - customise your event loop even more! 666 CHECK WATCHERS - customise your event loop even more!
546 $w = EV::check $callback 667 $w = EV::check $callback
547 $w = EV::check_ns $callback 668 $w = EV::check_ns $callback
669 $w = $loop->check ($callback)
670 $w = $loop->check_ns ($callback)
548 Call the callback just after the process wakes up again (after it 671 Call the callback just after the process wakes up again (after it
549 has gathered events), but before any other callbacks have been 672 has gathered events), but before any other callbacks have been
550 invoked. 673 invoked.
551 674
552 This is used to integrate other event-based software into the EV 675 This is used to integrate other event-based software into the EV
… …
563 or return; 686 or return;
564 687
565 # make the dispatcher handle any outstanding stuff 688 # make the dispatcher handle any outstanding stuff
566 ... not shown 689 ... not shown
567 690
568 # create an IO watcher for each and every socket 691 # create an I/O watcher for each and every socket
569 @snmp_watcher = ( 692 @snmp_watcher = (
570 (map { EV::io $_, EV::READ, sub { } } 693 (map { EV::io $_, EV::READ, sub { } }
571 keys %{ $dispatcher->{_descriptors} }), 694 keys %{ $dispatcher->{_descriptors} }),
572 695
573 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 696 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
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601 is done before the event loop blocks next and before "check" watchers 724 is done before the event loop blocks next and before "check" watchers
602 are being called, and only in the child after the fork. 725 are being called, and only in the child after the fork.
603 726
604 $w = EV::fork $callback 727 $w = EV::fork $callback
605 $w = EV::fork_ns $callback 728 $w = EV::fork_ns $callback
729 $w = $loop->fork ($callback)
730 $w = $loop->fork_ns ($callback)
606 Call the callback before the event loop is resumed in the child 731 Call the callback before the event loop is resumed in the child
607 process after a fork. 732 process after a fork.
608 733
609 The "fork_ns" variant doesn't start (activate) the newly created 734 The "fork_ns" variant doesn't start (activate) the newly created
610 watcher. 735 watcher.
736
737 EMBED WATCHERS - when one backend isn't enough...
738 This is a rather advanced watcher type that lets you embed one event
739 loop into another (currently only IO events are supported in the
740 embedded loop, other types of watchers might be handled in a delayed or
741 incorrect fashion and must not be used).
742
743 See the libev documentation at
744 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
745 _when_one_backend_> for more details.
746
747 In short, this watcher is most useful on BSD systems without working
748 kqueue to still be able to handle a large number of sockets:
749
750 my $socket_loop;
751
752 # check wether we use SELECT or POLL _and_ KQUEUE is supported
753 if (
754 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
755 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
756 ) {
757 # use kqueue for sockets
758 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
759 }
760
761 # use the default loop otherwise
762 $socket_loop ||= EV::default_loop;
763
764 $w = EV::embed $otherloop, $callback
765 $w = EV::embed_ns $otherloop, $callback
766 $w = $loop->embed ($otherloop, $callback)
767 $w = $loop->embed_ns ($otherloop, $callback)
768 Call the callback when the embedded event loop ($otherloop) has any
769 I/O activity. The $callback should alwas be specified as "undef" in
770 this version of EV, which means the embedded event loop will be
771 managed automatically.
772
773 The "embed_ns" variant doesn't start (activate) the newly created
774 watcher.
775
776PERL SIGNALS
777 While Perl signal handling (%SIG) is not affected by EV, the behaviour
778 with EV is as the same as any other C library: Perl-signals will only be
779 handled when Perl runs, which means your signal handler might be invoked
780 only the next time an event callback is invoked.
781
782 The solution is to use EV signal watchers (see "EV::signal"), which will
783 ensure proper operations with regards to other event watchers.
784
785 If you cannot do this for whatever reason, you can also force a watcher
786 to be called on every event loop iteration by installing a "EV::check"
787 watcher:
788
789 my $async_check = EV::check sub { };
790
791 This ensures that perl gets into control for a short time to handle any
792 pending signals, and also ensures (slightly) slower overall operation.
611 793
612THREADS 794THREADS
613 Threads are not supported by this module in any way. Perl pseudo-threads 795 Threads are not supported by this module in any way. Perl pseudo-threads
614 is evil stuff and must die. As soon as Perl gains real threads I will 796 is evil stuff and must die. As soon as Perl gains real threads I will
615 work on thread support for it. 797 work on thread support for it.
… …
630 812
631 On win32, there is no notion of fork so all this doesn't apply, of 813 On win32, there is no notion of fork so all this doesn't apply, of
632 course. 814 course.
633 815
634SEE ALSO 816SEE ALSO
635 EV::DNS. 817 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
818 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
819 with EV), Net::SNMP::EV (asynchronous SNMP).
636 820
637AUTHOR 821AUTHOR
638 Marc Lehmann <schmorp@schmorp.de> 822 Marc Lehmann <schmorp@schmorp.de>
639 http://home.schmorp.de/ 823 http://home.schmorp.de/
640 824

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