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Revision 1.12 by root, Tue Nov 27 07:27:10 2007 UTC vs.
Revision 1.21 by root, Sat Dec 22 16:48:33 2007 UTC

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37 # CHILD/PID STATUS CHANGES 37 # CHILD/PID STATUS CHANGES
38 38
39 my $w = EV::child 666, sub { 39 my $w = EV::child 666, sub {
40 my ($w, $revents) = @_; 40 my ($w, $revents) = @_;
41 my $status = $w->rstatus; 41 my $status = $w->rstatus;
42 };
43
44 # STAT CHANGES
45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_;
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::loop; # loop until EV::unloop is called or all watchers stop
46 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 52 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
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50 This module provides an interface to libev 56 This module provides an interface to libev
51 (<http://software.schmorp.de/pkg/libev.html>). While the documentation 57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
52 below is comprehensive, one might also consult the documentation of 58 below is comprehensive, one might also consult the documentation of
53 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
54 details on watcher semantics or some discussion on the available 60 details on watcher semantics or some discussion on the available
55 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).
56 99
57BASIC INTERFACE 100BASIC INTERFACE
58 $EV::DIED 101 $EV::DIED
59 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
60 callback throws an exception (with $@ containing thr error). The 103 callback throws an exception (with $@ containing the error). The
61 default prints an informative message and continues. 104 default prints an informative message and continues.
62 105
63 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.
64 118
65 $time = EV::time 119 $time = EV::time
66 Returns the current time in (fractional) seconds since the epoch. 120 Returns the current time in (fractional) seconds since the epoch.
67 121
68 $time = EV::now 122 $time = EV::now
123 $time = $loop->now
69 Returns the time the last event loop iteration has been started. 124 Returns the time the last event loop iteration has been started.
70 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
71 to it is usually faster then calling EV::time. 126 to it is usually faster then calling EV::time.
72 127
73 $method = EV::method 128 $backend = EV::backend
129 $backend = $loop->backend
74 Returns an integer describing the backend used by libev 130 Returns an integer describing the backend used by libev
75 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 131 (EV::METHOD_SELECT or EV::METHOD_EPOLL).
76 132
77 EV::loop [$flags] 133 EV::loop [$flags]
134 $loop->loop ([$flags])
78 Begin checking for events and calling callbacks. It returns when a 135 Begin checking for events and calling callbacks. It returns when a
79 callback calls EV::unloop. 136 callback calls EV::unloop.
80 137
81 The $flags argument can be one of the following: 138 The $flags argument can be one of the following:
82 139
83 0 as above 140 0 as above
84 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 141 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
85 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 142 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
86 143
87 EV::unloop [$how] 144 EV::unloop [$how]
145 $loop->unloop ([$how])
88 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,
89 makes the innermost call to EV::loop return. 147 makes the innermost call to EV::loop return.
90 148
91 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
92 EV::loop will return as fast as possible. 150 EV::loop will return as fast as possible.
93 151
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
94 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))
95 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
96 one-shot event without the need for managing a watcher object. 160 one-shot event without the need for managing a watcher object.
97 161
98 If $fh_or_undef is a filehandle or file descriptor, then $events 162 If $fh_or_undef is a filehandle or file descriptor, then $events
99 must be a bitset containing either "EV::READ", "EV::WRITE" or 163 must be a bitset containing either "EV::READ", "EV::WRITE" or
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104 If timeout is "undef" or negative, then there will be no timeout. 168 If timeout is "undef" or negative, then there will be no timeout.
105 Otherwise a EV::timer with this value will be started. 169 Otherwise a EV::timer with this value will be started.
106 170
107 When an error occurs or either the timeout or I/O watcher triggers, 171 When an error occurs or either the timeout or I/O watcher triggers,
108 then the callback will be called with the received event set (in 172 then the callback will be called with the received event set (in
109 general you can expect it to be a combination of "EV:ERROR", 173 general you can expect it to be a combination of "EV::ERROR",
110 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 174 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
111 175
112 EV::once doesn't return anything: the watchers stay active till 176 EV::once doesn't return anything: the watchers stay active till
113 either of them triggers, then they will be stopped and freed, and 177 either of them triggers, then they will be stopped and freed, and
114 the callback invoked. 178 the callback invoked.
115 179
116 WATCHER 180 EV::feed_fd_event ($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
201WATCHER OBJECTS
117 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
118 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,
119 you would create an EV::io watcher for that: 204 you would create an EV::io watcher for that:
120 205
121 my $watcher = EV::io *STDIN, EV::READ, sub { 206 my $watcher = EV::io *STDIN, EV::READ, sub {
122 my ($watcher, $revents) = @_; 207 my ($watcher, $revents) = @_;
123 warn "yeah, STDIN should not be readable without blocking!\n" 208 warn "yeah, STDIN should now be readable without blocking!\n"
124 }; 209 };
125 210
126 All watchers can be active (waiting for events) or inactive (paused). 211 All watchers can be active (waiting for events) or inactive (paused).
127 Only active watchers will have their callbacks invoked. All callbacks 212 Only active watchers will have their callbacks invoked. All callbacks
128 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
129 received events. 214 received events.
130 215
131 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
132 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
133 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,
134 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
135 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
136 (which uses EV::TIMEOUT). 221 (which uses EV::TIMEOUT).
137 222
138 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
139 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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145 230
146 Also, all methods changing some aspect of a watcher (->set, ->priority, 231 Also, all methods changing some aspect of a watcher (->set, ->priority,
147 ->fh and so on) automatically stop and start it again if it is active, 232 ->fh and so on) automatically stop and start it again if it is active,
148 which means pending events get lost. 233 which means pending events get lost.
149 234
150 WATCHER TYPES 235 COMMON WATCHER METHODS
151 Now lets move to the existing watcher types and asociated methods. 236 This section lists methods common to all watchers.
152
153 The following methods are available for all watchers. Then followes a
154 description of each watcher constructor (EV::io, EV::timer,
155 EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and
156 EV::check), followed by any type-specific methods (if any).
157 237
158 $w->start 238 $w->start
159 Starts a watcher if it isn't active already. Does nothing to an 239 Starts a watcher if it isn't active already. Does nothing to an
160 already active watcher. By default, all watchers start out in the 240 already active watcher. By default, all watchers start out in the
161 active state (see the description of the "_ns" variants if you need 241 active state (see the description of the "_ns" variants if you need
162 stopped watchers). 242 stopped watchers).
163 243
164 $w->stop 244 $w->stop
165 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
166 (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
167 callback invocation), regardless of wether the watcher was active or 247 callback invocation), regardless of whether the watcher was active
168 not. 248 or not.
169 249
170 $bool = $w->is_active 250 $bool = $w->is_active
171 Returns true if the watcher is active, false otherwise. 251 Returns true if the watcher is active, false otherwise.
172 252
173 $current_data = $w->data 253 $current_data = $w->data
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196 The default priority of any newly-created watcher is 0. 276 The default priority of any newly-created watcher is 0.
197 277
198 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
199 are subject to almost certain change. 279 are subject to almost certain change.
200 280
201 $w->trigger ($revents) 281 $w->invoke ($revents)
202 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.
203 292
204 $previous_state = $w->keepalive ($bool) 293 $previous_state = $w->keepalive ($bool)
205 Normally, "EV::loop" will return when there are no active watchers 294 Normally, "EV::loop" will return when there are no active watchers
206 (which is a "deadlock" because no progress can be made anymore). 295 (which is a "deadlock" because no progress can be made anymore).
207 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
208 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
209 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
210 for their task :). 299 for their task :).
211 300
212 Sometimes, however, this gets in your way, for example when you the 301 Sometimes, however, this gets in your way, for example when the
213 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
214 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
215 module written by somebody else even). Then you might want any 304 module written by somebody else even). Then you might want any
216 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
217 "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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222 returning. 311 returning.
223 312
224 The initial value for keepalive is true (enabled), and you cna 313 The initial value for keepalive is true (enabled), and you cna
225 change it any time. 314 change it any time.
226 315
227 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
228 the event loop from running just because of that watcher. 317 the event loop from running just because of that watcher.
229 318
230 my $udp_socket = ... 319 my $udp_socket = ...
231 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 320 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
232 $udp_watcher->keepalive (0); 321 $1000udp_watcher->keepalive (0);
233 322
323 $loop = $w->loop
324 Return the loop that this watcher is attached to.
325
326WATCHER TYPES
327 Each of the following subsections describes a single watcher type.
328
329 I/O WATCHERS - is this file descriptor readable or writable?
234 $w = EV::io $fileno_or_fh, $eventmask, $callback 330 $w = EV::io $fileno_or_fh, $eventmask, $callback
235 $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)
236 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
237 when the events specified in $eventmask. 335 when at least one of events specified in $eventmask occurs.
238 336
239 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:
240 338
241 EV::READ wait until read() wouldn't block anymore 339 EV::READ wait until read() wouldn't block anymore
242 EV::WRITE wait until write() wouldn't block anymore 340 EV::WRITE wait until write() wouldn't block anymore
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254 352
255 $current_eventmask = $w->events 353 $current_eventmask = $w->events
256 $old_eventmask = $w->events ($new_eventmask) 354 $old_eventmask = $w->events ($new_eventmask)
257 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.
258 356
357 TIMER WATCHERS - relative and optionally repeating timeouts
259 $w = EV::timer $after, $repeat, $callback 358 $w = EV::timer $after, $repeat, $callback
260 $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)
261 Calls the callback after $after seconds (which may be fractional). 362 Calls the callback after $after seconds (which may be fractional).
262 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
263 $repeat value as $after) after the callback returns. 364 $repeat value as $after) after the callback returns.
264 365
265 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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277 The "timer_ns" variant doesn't start (activate) the newly created 378 The "timer_ns" variant doesn't start (activate) the newly created
278 watcher. 379 watcher.
279 380
280 $w->set ($after, $repeat) 381 $w->set ($after, $repeat)
281 Reconfigures the watcher, see the constructor above for details. Can 382 Reconfigures the watcher, see the constructor above for details. Can
282 be at any time. 383 be called at any time.
283 384
284 $w->again 385 $w->again
285 Similar to the "start" method, but has special semantics for 386 Similar to the "start" method, but has special semantics for
286 repeating timers: 387 repeating timers:
287 388
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298 This behaviour is useful when you have a timeout for some IO 399 This behaviour is useful when you have a timeout for some IO
299 operation. You create a timer object with the same value for $after 400 operation. You create a timer object with the same value for $after
300 and $repeat, and then, in the read/write watcher, run the "again" 401 and $repeat, and then, in the read/write watcher, run the "again"
301 method on the timeout. 402 method on the timeout.
302 403
404 PERIODIC WATCHERS - to cron or not to cron?
303 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 405 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
304 $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)
305 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
306 absolute times. Apart from creating "simple" timers that trigger 410 absolute times. Apart from creating "simple" timers that trigger
307 "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
308 absolute timers and more complex, cron-like, setups that are not 412 absolute timers and more complex, cron-like, setups that are not
309 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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372 The "periodic_ns" variant doesn't start (activate) the newly created 476 The "periodic_ns" variant doesn't start (activate) the newly created
373 watcher. 477 watcher.
374 478
375 $w->set ($at, $interval, $reschedule_cb) 479 $w->set ($at, $interval, $reschedule_cb)
376 Reconfigures the watcher, see the constructor above for details. Can 480 Reconfigures the watcher, see the constructor above for details. Can
377 be at any time. 481 be called at any time.
378 482
379 $w->again 483 $w->again
380 Simply stops and starts the watcher again. 484 Simply stops and starts the watcher again.
381 485
486 $time = $w->at
487 Return the time that the watcher is expected to trigger next.
488
489 SIGNAL WATCHERS - signal me when a signal gets signalled!
382 $w = EV::signal $signal, $callback 490 $w = EV::signal $signal, $callback
383 $w = EV::signal_ns $signal, $callback 491 $w = EV::signal_ns $signal, $callback
384 Call the callback when $signal is received (the signal can be 492 Call the callback when $signal is received (the signal can be
385 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).
386 494
387 EV will grab the signal for the process (the kernel only allows one 495 EV will grab the signal for the process (the kernel only allows one
388 component to receive a signal at a time) when you start a signal 496 component to receive a signal at a time) when you start a signal
389 watcher, and removes it again when you stop it. Perl does the same 497 watcher, and removes it again when you stop it. Perl does the same
390 when you add/remove callbacks to %SIG, so watch out. 498 when you add/remove callbacks to %SIG, so watch out.
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394 The "signal_ns" variant doesn't start (activate) the newly created 502 The "signal_ns" variant doesn't start (activate) the newly created
395 watcher. 503 watcher.
396 504
397 $w->set ($signal) 505 $w->set ($signal)
398 Reconfigures the watcher, see the constructor above for details. Can 506 Reconfigures the watcher, see the constructor above for details. Can
399 be at any time. 507 be called at any time.
400 508
401 $current_signum = $w->signal 509 $current_signum = $w->signal
402 $old_signum = $w->signal ($new_signal) 510 $old_signum = $w->signal ($new_signal)
403 Returns the previously set signal (always as a number not name) and 511 Returns the previously set signal (always as a number not name) and
404 optionally set a new one. 512 optionally set a new one.
405 513
514 CHILD WATCHERS - watch out for process status changes
406 $w = EV::child $pid, $callback 515 $w = EV::child $pid, $callback
407 $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)
408 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
409 $pid is 0) has been received. More precisely: when the process 520 $pid is 0) has been received. More precisely: when the process
410 receives a SIGCHLD, EV will fetch the outstanding exit/wait status 521 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status
411 for all changed/zombie children and call the callback. 522 for all changed/zombie children and call the callback.
412 523
413 You can access both status and pid by using the "rstatus" and "rpid" 524 It is valid (and fully supported) to install a child watcher after a
525 child has exited but before the event loop has started its next
526 iteration (for example, first you "fork", then the new child process
527 might exit, and only then do you install a child watcher in the
528 parent for the new pid).
529
530 You can access both exit (or tracing) status and pid by using the
414 methods on the watcher object. 531 "rstatus" and "rpid" methods on the watcher object.
415 532
416 You can have as many pid watchers per pid as you want. 533 You can have as many pid watchers per pid as you want, they will all
534 be called.
417 535
418 The "child_ns" variant doesn't start (activate) the newly created 536 The "child_ns" variant doesn't start (activate) the newly created
419 watcher. 537 watcher.
420 538
421 $w->set ($pid) 539 $w->set ($pid)
422 Reconfigures the watcher, see the constructor above for details. Can 540 Reconfigures the watcher, see the constructor above for details. Can
423 be at any time. 541 be called at any time.
424 542
425 $current_pid = $w->pid 543 $current_pid = $w->pid
426 $old_pid = $w->pid ($new_pid) 544 $old_pid = $w->pid ($new_pid)
427 Returns the previously set process id and optionally set a new one. 545 Returns the previously set process id and optionally set a new one.
428 546
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432 550
433 $pid = $w->rpid 551 $pid = $w->rpid
434 Return the pid of the awaited child (useful when you have installed 552 Return the pid of the awaited child (useful when you have installed
435 a watcher for all pids). 553 a watcher for all pids).
436 554
555 STAT WATCHERS - did the file attributes just change?
556 $w = EV::stat $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)
560 Call the callback when a file status change has been detected on
561 $path. The $path does not need to exist, changing from "path exists"
562 to "path does not exist" is a status change like any other.
563
564 The $interval is a recommended polling interval for systems where
565 OS-supported change notifications don't exist or are not supported.
566 If you use 0 then an unspecified default is used (which is highly
567 recommended!), which is to be expected to be around five seconds
568 usually.
569
570 This watcher type is not meant for massive numbers of stat watchers,
571 as even with OS-supported change notifications, this can be
572 resource-intensive.
573
574 The "stat_ns" variant doesn't start (activate) the newly created
575 watcher.
576
577 ... = $w->stat
578 This call is very similar to the perl "stat" built-in: It stats
579 (using "lstat") the path specified in the watcher and sets perls
580 stat cache (as well as EV's idea of the current stat values) to the
581 values found.
582
583 In scalar context, a boolean is return indicating success or failure
584 of the stat. In list context, the same 13-value list as with stat is
585 returned (except that the blksize and blocks fields are not
586 reliable).
587
588 In the case of an error, errno is set to "ENOENT" (regardless of the
589 actual error value) and the "nlink" value is forced to zero (if the
590 stat was successful then nlink is guaranteed to be non-zero).
591
592 See also the next two entries for more info.
593
594 ... = $w->attr
595 Just like "$w->stat", but without the initial stat'ing: this returns
596 the values most recently detected by EV. See the next entry for more
597 info.
598
599 ... = $w->prev
600 Just like "$w->stat", but without the initial stat'ing: this returns
601 the previous set of values, before the change.
602
603 That is, when the watcher callback is invoked, "$w->prev" will be
604 set to the values found *before* a change was detected, while
605 "$w->attr" returns the values found leading to the change detection.
606 The difference (if any) between "prev" and "attr" is what triggered
607 the callback.
608
609 If you did something to the filesystem object and do not want to
610 trigger yet another change, you can call "stat" to update EV's idea
611 of what the current attributes are.
612
613 $w->set ($path, $interval)
614 Reconfigures the watcher, see the constructor above for details. Can
615 be called at any time.
616
617 $current_path = $w->path
618 $old_path = $w->path ($new_path)
619 Returns the previously set path and optionally set a new one.
620
621 $current_interval = $w->interval
622 $old_interval = $w->interval ($new_interval)
623 Returns the previously set interval and optionally set a new one.
624 Can be used to query the actual interval used.
625
626 IDLE WATCHERS - when you've got nothing better to do...
437 $w = EV::idle $callback 627 $w = EV::idle $callback
438 $w = EV::idle_ns $callback 628 $w = EV::idle_ns $callback
629 $w = $loop->idle ($callback)
630 $w = $loop->idle_ns ($callback)
439 Call the callback when there are no pending io, timer/periodic, 631 Call the callback when there are no other pending watchers of the
440 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".
441 640
442 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,
443 and they will be called repeatedly until stopped. 642 and they will be called repeatedly until stopped.
444 643
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.
649
445 The "idle_ns" variant doesn't start (activate) the newly created 650 The "idle_ns" variant doesn't start (activate) the newly created
446 watcher. 651 watcher.
447 652
653 PREPARE WATCHERS - customise your event loop!
448 $w = EV::prepare $callback 654 $w = EV::prepare $callback
449 $w = EV::prepare_ns $callback 655 $w = EV::prepare_ns $callback
656 $w = $loop->prepare ($callback)
657 $w = $loop->prepare_ns ($callback)
450 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
451 create/modify any watchers at this point. 659 create/modify any watchers at this point.
452 660
453 See the EV::check watcher, below, for explanations and an example. 661 See the EV::check watcher, below, for explanations and an example.
454 662
455 The "prepare_ns" variant doesn't start (activate) the newly created 663 The "prepare_ns" variant doesn't start (activate) the newly created
456 watcher. 664 watcher.
457 665
666 CHECK WATCHERS - customise your event loop even more!
458 $w = EV::check $callback 667 $w = EV::check $callback
459 $w = EV::check_ns $callback 668 $w = EV::check_ns $callback
669 $w = $loop->check ($callback)
670 $w = $loop->check_ns ($callback)
460 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
461 has gathered events), but before any other callbacks have been 672 has gathered events), but before any other callbacks have been
462 invoked. 673 invoked.
463 674
464 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
… …
475 or return; 686 or return;
476 687
477 # make the dispatcher handle any outstanding stuff 688 # make the dispatcher handle any outstanding stuff
478 ... not shown 689 ... not shown
479 690
480 # create an IO watcher for each and every socket 691 # create an I/O watcher for each and every socket
481 @snmp_watcher = ( 692 @snmp_watcher = (
482 (map { EV::io $_, EV::READ, sub { } } 693 (map { EV::io $_, EV::READ, sub { } }
483 keys %{ $dispatcher->{_descriptors} }), 694 keys %{ $dispatcher->{_descriptors} }),
484 695
485 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 696 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
… …
505 watchers are destroyed before this cna happen (remember EV::check 716 watchers are destroyed before this cna happen (remember EV::check
506 gets called first). 717 gets called first).
507 718
508 The "check_ns" variant doesn't start (activate) the newly created 719 The "check_ns" variant doesn't start (activate) the newly created
509 watcher. 720 watcher.
721
722 FORK WATCHERS - the audacity to resume the event loop after a fork
723 Fork watchers are called when a "fork ()" was detected. The invocation
724 is done before the event loop blocks next and before "check" watchers
725 are being called, and only in the child after the fork.
726
727 $w = EV::fork $callback
728 $w = EV::fork_ns $callback
729 $w = $loop->fork ($callback)
730 $w = $loop->fork_ns ($callback)
731 Call the callback before the event loop is resumed in the child
732 process after a fork.
733
734 The "fork_ns" variant doesn't start (activate) the newly created
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.
510 793
511THREADS 794THREADS
512 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
513 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
514 work on thread support for it. 797 work on thread support for it.
… …
529 812
530 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
531 course. 814 course.
532 815
533SEE ALSO 816SEE ALSO
534 L<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).
535 820
536AUTHOR 821AUTHOR
537 Marc Lehmann <schmorp@schmorp.de> 822 Marc Lehmann <schmorp@schmorp.de>
538 http://home.schmorp.de/ 823 http://home.schmorp.de/
539 824

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