ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/EV/README
(Generate patch)

Comparing EV/README (file contents):
Revision 1.15 by root, Wed Dec 5 14:06:50 2007 UTC vs.
Revision 1.22 by root, Mon Jan 28 12:24:05 2008 UTC

… …
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 7
8 # TIMERS 8 # TIMERS
9 9
10 my $w = EV::timer 2, 0, sub { 10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s"; 11 warn "is called after 2s";
12 }; 12 };
13 13
14 my $w = EV::timer 2, 2, sub { 14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)"; 15 warn "is called roughly every 2s (repeat = 2)";
16 }; 16 };
17 17
18 undef $w; # destroy event watcher again 18 undef $w; # destroy event watcher again
19 19
20 my $w = EV::periodic 0, 60, 0, sub { 20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly"; 21 warn "is called every minute, on the minute, exactly";
22 }; 22 };
23
24 # IO 23
25 24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub { 26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask 27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>; 28 warn "stdin is readable, you entered: ", <STDIN>;
29 }; 29 };
30 30
31 # SIGNALS 31 # SIGNALS
32 32
33 my $w = EV::signal 'QUIT', sub { 33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n"; 34 warn "sigquit received\n";
35 }; 35 };
36 36
37 # CHILD/PID STATUS CHANGES 37 # CHILD/PID STATUS CHANGES
38 38
39 my $w = EV::child 666, sub { 39 my $w = EV::child 666, 0, sub {
40 my ($w, $revents) = @_; 40 my ($w, $revents) = @_;
41 my $status = $w->rstatus; 41 my $status = $w->rstatus;
42 }; 42 };
43 43
44 # STAT CHANGES 44 # STAT CHANGES
45 my $w = EV::stat "/etc/passwd", 10, sub { 45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_; 46 my ($w, $revents) = @_;
47 warn $w->path, " has changed somehow.\n"; 47 warn $w->path, " has changed somehow.\n";
48 }; 48 };
49 49
50 # MAINLOOP 50 # MAINLOOP
51 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
52 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
53 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 53 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
54 54
55DESCRIPTION 55DESCRIPTION
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
100 $count = EV::loop_count 152 $count = EV::loop_count
153 $count = $loop->loop_count
101 Return the number of times the event loop has polled for new events. 154 Return the number of times the event loop has polled for new events.
102 Sometiems useful as a generation counter. 155 Sometiems useful as a generation counter.
103 156
104 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))
105 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
106 one-shot event without the need for managing a watcher object. 160 one-shot event without the need for managing a watcher object.
107 161
108 If $fh_or_undef is a filehandle or file descriptor, then $events 162 If $fh_or_undef is a filehandle or file descriptor, then $events
109 must be a bitset containing either "EV::READ", "EV::WRITE" or 163 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
114 If timeout is "undef" or negative, then there will be no timeout. 168 If timeout is "undef" or negative, then there will be no timeout.
115 Otherwise a EV::timer with this value will be started. 169 Otherwise a EV::timer with this value will be started.
116 170
117 When an error occurs or either the timeout or I/O watcher triggers, 171 When an error occurs or either the timeout or I/O watcher triggers,
118 then the callback will be called with the received event set (in 172 then the callback will be called with the received event set (in
119 general you can expect it to be a combination of "EV:ERROR", 173 general you can expect it to be a combination of "EV::ERROR",
120 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 174 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
121 175
122 EV::once doesn't return anything: the watchers stay active till 176 EV::once doesn't return anything: the watchers stay active till
123 either of them triggers, then they will be stopped and freed, and 177 either of them triggers, then they will be stopped and freed, and
124 the callback invoked. 178 the callback invoked.
125 179
180 EV::feed_fd_event ($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
126 WATCHER OBJECTS 201WATCHER OBJECTS
127 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
128 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,
129 you would create an EV::io watcher for that: 204 you would create an EV::io watcher for that:
130 205
131 my $watcher = EV::io *STDIN, EV::READ, sub { 206 my $watcher = EV::io *STDIN, EV::READ, sub {
132 my ($watcher, $revents) = @_; 207 my ($watcher, $revents) = @_;
133 warn "yeah, STDIN should not be readable without blocking!\n" 208 warn "yeah, STDIN should now be readable without blocking!\n"
134 }; 209 };
135 210
136 All watchers can be active (waiting for events) or inactive (paused). 211 All watchers can be active (waiting for events) or inactive (paused).
137 Only active watchers will have their callbacks invoked. All callbacks 212 Only active watchers will have their callbacks invoked. All callbacks
138 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
139 received events. 214 received events.
140 215
141 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
142 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
143 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,
144 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
145 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
146 (which uses EV::TIMEOUT). 221 (which uses EV::TIMEOUT).
147 222
148 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
149 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
… …
167 stopped watchers). 242 stopped watchers).
168 243
169 $w->stop 244 $w->stop
170 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
171 (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
172 callback invocation), regardless of wether the watcher was active or 247 callback invocation), regardless of whether the watcher was active
173 not. 248 or not.
174 249
175 $bool = $w->is_active 250 $bool = $w->is_active
176 Returns true if the watcher is active, false otherwise. 251 Returns true if the watcher is active, false otherwise.
177 252
178 $current_data = $w->data 253 $current_data = $w->data
… …
201 The default priority of any newly-created watcher is 0. 276 The default priority of any newly-created watcher is 0.
202 277
203 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
204 are subject to almost certain change. 279 are subject to almost certain change.
205 280
206 $w->trigger ($revents) 281 $w->invoke ($revents)
207 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.
208 292
209 $previous_state = $w->keepalive ($bool) 293 $previous_state = $w->keepalive ($bool)
210 Normally, "EV::loop" will return when there are no active watchers 294 Normally, "EV::loop" will return when there are no active watchers
211 (which is a "deadlock" because no progress can be made anymore). 295 (which is a "deadlock" because no progress can be made anymore).
212 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
213 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
214 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
215 for their task :). 299 for their task :).
216 300
217 Sometimes, however, this gets in your way, for example when you the 301 Sometimes, however, this gets in your way, for example when the
218 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
219 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
220 module written by somebody else even). Then you might want any 304 module written by somebody else even). Then you might want any
221 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
222 "EV::loop" from returning just because you happen to have this 306 "EV::loop" from returning just because you happen to have this
… …
227 returning. 311 returning.
228 312
229 The initial value for keepalive is true (enabled), and you cna 313 The initial value for keepalive is true (enabled), and you cna
230 change it any time. 314 change it any time.
231 315
232 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
233 the event loop from running just because of that watcher. 317 the event loop from running just because of that watcher.
234 318
235 my $udp_socket = ... 319 my $udp_socket = ...
236 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 320 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
237 $udp_watcher->keepalive (0); 321 $1000udp_watcher->keepalive (0);
238 322
323 $loop = $w->loop
324 Return the loop that this watcher is attached to.
325
239 WATCHER TYPES 326WATCHER TYPES
240 Each of the following subsections describes a single watcher type. 327 Each of the following subsections describes a single watcher type.
241 328
242 IO WATCHERS - is this file descriptor readable or writable? 329 I/O WATCHERS - is this file descriptor readable or writable?
243 $w = EV::io $fileno_or_fh, $eventmask, $callback 330 $w = EV::io $fileno_or_fh, $eventmask, $callback
244 $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)
245 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
246 when at least one of events specified in $eventmask occurs. 335 when at least one of events specified in $eventmask occurs.
247 336
248 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:
249 338
… …
266 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.
267 356
268 TIMER WATCHERS - relative and optionally repeating timeouts 357 TIMER WATCHERS - relative and optionally repeating timeouts
269 $w = EV::timer $after, $repeat, $callback 358 $w = EV::timer $after, $repeat, $callback
270 $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)
271 Calls the callback after $after seconds (which may be fractional). 362 Calls the callback after $after seconds (which may be fractional).
272 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
273 $repeat value as $after) after the callback returns. 364 $repeat value as $after) after the callback returns.
274 365
275 This means that the callback would be called roughly after $after 366 This means that the callback would be called roughly after $after
… …
311 method on the timeout. 402 method on the timeout.
312 403
313 PERIODIC WATCHERS - to cron or not to cron? 404 PERIODIC WATCHERS - to cron or not to cron?
314 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 405 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
315 $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, $callback)
316 Similar to EV::timer, but is not based on relative timeouts but on 409 Similar to EV::timer, but is not based on relative timeouts but on
317 absolute times. Apart from creating "simple" timers that trigger 410 absolute times. Apart from creating "simple" timers that trigger
318 "at" the specified time, it can also be used for non-drifting 411 "at" the specified time, it can also be used for non-drifting
319 absolute timers and more complex, cron-like, setups that are not 412 absolute timers and more complex, cron-like, setups that are not
320 adversely affected by time jumps (i.e. when the system clock is 413 adversely affected by time jumps (i.e. when the system clock is
321 changed by explicit date -s or other means such as ntpd). It is also 414 changed by explicit date -s or other means such as ntpd). It is also
322 the most complex watcher type in EV. 415 the most complex watcher type in EV.
323 416
324 It has three distinct "modes": 417 It has three distinct "modes":
325 418
326 * absolute timer ($interval = $reschedule_cb = 0) 419 * absolute timer ($interval = $reschedule_cb = 0)
420
327 This time simply fires at the wallclock time $at and doesn't 421 This time simply fires at the wallclock time $at and doesn't
328 repeat. It will not adjust when a time jump occurs, that is, if 422 repeat. It will not adjust when a time jump occurs, that is, if
329 it is to be run at January 1st 2011 then it will run when the 423 it is to be run at January 1st 2011 then it will run when the
330 system time reaches or surpasses this time. 424 system time reaches or surpasses this time.
331 425
332 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 426 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
427
333 In this mode the watcher will always be scheduled to time out at 428 In this mode the watcher will always be scheduled to time out at
334 the next "$at + N * $interval" time (for some integer N) and 429 the next "$at + N * $interval" time (for some integer N) and
335 then repeat, regardless of any time jumps. 430 then repeat, regardless of any time jumps.
336 431
337 This can be used to create timers that do not drift with respect 432 This can be used to create timers that do not drift with respect
… …
346 Another way to think about it (for the mathematically inclined) 441 Another way to think about it (for the mathematically inclined)
347 is that EV::periodic will try to run the callback in this mode 442 is that EV::periodic will try to run the callback in this mode
348 at the next possible time where "$time = $at (mod $interval)", 443 at the next possible time where "$time = $at (mod $interval)",
349 regardless of any time jumps. 444 regardless of any time jumps.
350 445
351 * manual reschedule mode ($reschedule_cb = coderef) 446 * manual reschedule mode ($reschedule_cb = coderef)
447
352 In this mode $interval and $at are both being ignored. Instead, 448 In this mode $interval and $at are both being ignored. Instead,
353 each time the periodic watcher gets scheduled, the reschedule 449 each time the periodic watcher gets scheduled, the reschedule
354 callback ($reschedule_cb) will be called with the watcher as 450 callback ($reschedule_cb) will be called with the watcher as
355 first, and the current time as second argument. 451 first, and the current time as second argument.
356 452
… …
388 be called at any time. 484 be called at any time.
389 485
390 $w->again 486 $w->again
391 Simply stops and starts the watcher again. 487 Simply stops and starts the watcher again.
392 488
489 $time = $w->at
490 Return the time that the watcher is expected to trigger next.
491
393 SIGNAL WATCHERS - signal me when a signal gets signalled! 492 SIGNAL WATCHERS - signal me when a signal gets signalled!
394 $w = EV::signal $signal, $callback 493 $w = EV::signal $signal, $callback
395 $w = EV::signal_ns $signal, $callback 494 $w = EV::signal_ns $signal, $callback
396 Call the callback when $signal is received (the signal can be 495 Call the callback when $signal is received (the signal can be
397 specified by number or by name, just as with "kill" or %SIG). 496 specified by number or by name, just as with "kill" or %SIG).
… …
414 $old_signum = $w->signal ($new_signal) 513 $old_signum = $w->signal ($new_signal)
415 Returns the previously set signal (always as a number not name) and 514 Returns the previously set signal (always as a number not name) and
416 optionally set a new one. 515 optionally set a new one.
417 516
418 CHILD WATCHERS - watch out for process status changes 517 CHILD WATCHERS - watch out for process status changes
419 $w = EV::child $pid, $callback 518 $w = EV::child $pid, $trace, $callback
420 $w = EV::child_ns $pid, $callback 519 $w = EV::child_ns $pid, $trace, $callback
520 $w = $loop->child ($pid, $trace, $callback)
521 $w = $loop->child_ns ($pid, $trace, $callback)
421 Call the callback when a status change for pid $pid (or any pid if 522 Call the callback when a status change for pid $pid (or any pid if
422 $pid is 0) has been received. More precisely: when the process 523 $pid is 0) has been received (a status change happens when the
524 process terminates or is killed, or, when trace is true,
525 additionally when it is stopped or continued). More precisely: when
423 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 526 the process receives a "SIGCHLD", EV will fetch the outstanding
424 for all changed/zombie children and call the callback. 527 exit/wait status for all changed/zombie children and call the
528 callback.
425 529
426 It is valid (and fully supported) to install a child watcher after a 530 It is valid (and fully supported) to install a child watcher after a
427 child has exited but before the event loop has started its next 531 child has exited but before the event loop has started its next
428 iteration (for example, first you "fork", then the new child process 532 iteration (for example, first you "fork", then the new child process
429 might exit, and only then do you install a child watcher in the 533 might exit, and only then do you install a child watcher in the
… …
436 be called. 540 be called.
437 541
438 The "child_ns" variant doesn't start (activate) the newly created 542 The "child_ns" variant doesn't start (activate) the newly created
439 watcher. 543 watcher.
440 544
441 $w->set ($pid) 545 $w->set ($pid, $trace)
442 Reconfigures the watcher, see the constructor above for details. Can 546 Reconfigures the watcher, see the constructor above for details. Can
443 be called at any time. 547 be called at any time.
444 548
445 $current_pid = $w->pid 549 $current_pid = $w->pid
446 $old_pid = $w->pid ($new_pid)
447 Returns the previously set process id and optionally set a new one. 550 Returns the previously set process id and optionally set a new one.
448 551
449 $exit_status = $w->rstatus 552 $exit_status = $w->rstatus
450 Return the exit/wait status (as returned by waitpid, see the waitpid 553 Return the exit/wait status (as returned by waitpid, see the waitpid
451 entry in perlfunc). 554 entry in perlfunc).
… …
455 a watcher for all pids). 558 a watcher for all pids).
456 559
457 STAT WATCHERS - did the file attributes just change? 560 STAT WATCHERS - did the file attributes just change?
458 $w = EV::stat $path, $interval, $callback 561 $w = EV::stat $path, $interval, $callback
459 $w = EV::stat_ns $path, $interval, $callback 562 $w = EV::stat_ns $path, $interval, $callback
563 $w = $loop->stat ($path, $interval, $callback)
564 $w = $loop->stat_ns ($path, $interval, $callback)
460 Call the callback when a file status change has been detected on 565 Call the callback when a file status change has been detected on
461 $path. The $path does not need to exist, changing from "path exists" 566 $path. The $path does not need to exist, changing from "path exists"
462 to "path does not exist" is a status change like any other. 567 to "path does not exist" is a status change like any other.
463 568
464 The $interval is a recommended polling interval for systems where 569 The $interval is a recommended polling interval for systems where
… …
524 Can be used to query the actual interval used. 629 Can be used to query the actual interval used.
525 630
526 IDLE WATCHERS - when you've got nothing better to do... 631 IDLE WATCHERS - when you've got nothing better to do...
527 $w = EV::idle $callback 632 $w = EV::idle $callback
528 $w = EV::idle_ns $callback 633 $w = EV::idle_ns $callback
634 $w = $loop->idle ($callback)
635 $w = $loop->idle_ns ($callback)
529 Call the callback when there are no pending io, timer/periodic, 636 Call the callback when there are no other pending watchers of the
530 signal or child events, i.e. when the process is idle. 637 same or higher priority (excluding check, prepare and other idle
638 watchers of the same or lower priority, of course). They are called
639 idle watchers because when the watcher is the highest priority
640 pending event in the process, the process is considered to be idle
641 at that priority.
642
643 If you want a watcher that is only ever called when *no* other
644 events are outstanding you have to set the priority to "EV::MINPRI".
531 645
532 The process will not block as long as any idle watchers are active, 646 The process will not block as long as any idle watchers are active,
533 and they will be called repeatedly until stopped. 647 and they will be called repeatedly until stopped.
648
649 For example, if you have idle watchers at priority 0 and 1, and an
650 I/O watcher at priority 0, then the idle watcher at priority 1 and
651 the I/O watcher will always run when ready. Only when the idle
652 watcher at priority 1 is stopped and the I/O watcher at priority 0
653 is not pending with the 0-priority idle watcher be invoked.
534 654
535 The "idle_ns" variant doesn't start (activate) the newly created 655 The "idle_ns" variant doesn't start (activate) the newly created
536 watcher. 656 watcher.
537 657
538 PREPARE WATCHERS - customise your event loop! 658 PREPARE WATCHERS - customise your event loop!
539 $w = EV::prepare $callback 659 $w = EV::prepare $callback
540 $w = EV::prepare_ns $callback 660 $w = EV::prepare_ns $callback
661 $w = $loop->prepare ($callback)
662 $w = $loop->prepare_ns ($callback)
541 Call the callback just before the process would block. You can still 663 Call the callback just before the process would block. You can still
542 create/modify any watchers at this point. 664 create/modify any watchers at this point.
543 665
544 See the EV::check watcher, below, for explanations and an example. 666 See the EV::check watcher, below, for explanations and an example.
545 667
… …
547 watcher. 669 watcher.
548 670
549 CHECK WATCHERS - customise your event loop even more! 671 CHECK WATCHERS - customise your event loop even more!
550 $w = EV::check $callback 672 $w = EV::check $callback
551 $w = EV::check_ns $callback 673 $w = EV::check_ns $callback
674 $w = $loop->check ($callback)
675 $w = $loop->check_ns ($callback)
552 Call the callback just after the process wakes up again (after it 676 Call the callback just after the process wakes up again (after it
553 has gathered events), but before any other callbacks have been 677 has gathered events), but before any other callbacks have been
554 invoked. 678 invoked.
555 679
556 This is used to integrate other event-based software into the EV 680 This is used to integrate other event-based software into the EV
… …
567 or return; 691 or return;
568 692
569 # make the dispatcher handle any outstanding stuff 693 # make the dispatcher handle any outstanding stuff
570 ... not shown 694 ... not shown
571 695
572 # create an IO watcher for each and every socket 696 # create an I/O watcher for each and every socket
573 @snmp_watcher = ( 697 @snmp_watcher = (
574 (map { EV::io $_, EV::READ, sub { } } 698 (map { EV::io $_, EV::READ, sub { } }
575 keys %{ $dispatcher->{_descriptors} }), 699 keys %{ $dispatcher->{_descriptors} }),
576 700
577 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 701 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
… …
605 is done before the event loop blocks next and before "check" watchers 729 is done before the event loop blocks next and before "check" watchers
606 are being called, and only in the child after the fork. 730 are being called, and only in the child after the fork.
607 731
608 $w = EV::fork $callback 732 $w = EV::fork $callback
609 $w = EV::fork_ns $callback 733 $w = EV::fork_ns $callback
734 $w = $loop->fork ($callback)
735 $w = $loop->fork_ns ($callback)
610 Call the callback before the event loop is resumed in the child 736 Call the callback before the event loop is resumed in the child
611 process after a fork. 737 process after a fork.
612 738
613 The "fork_ns" variant doesn't start (activate) the newly created 739 The "fork_ns" variant doesn't start (activate) the newly created
614 watcher. 740 watcher.
741
742 EMBED WATCHERS - when one backend isn't enough...
743 This is a rather advanced watcher type that lets you embed one event
744 loop into another (currently only IO events are supported in the
745 embedded loop, other types of watchers might be handled in a delayed or
746 incorrect fashion and must not be used).
747
748 See the libev documentation at
749 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
750 _when_one_backend_> for more details.
751
752 In short, this watcher is most useful on BSD systems without working
753 kqueue to still be able to handle a large number of sockets:
754
755 my $socket_loop;
756
757 # check wether we use SELECT or POLL _and_ KQUEUE is supported
758 if (
759 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
760 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
761 ) {
762 # use kqueue for sockets
763 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
764 }
765
766 # use the default loop otherwise
767 $socket_loop ||= EV::default_loop;
768
769 $w = EV::embed $otherloop, $callback
770 $w = EV::embed_ns $otherloop, $callback
771 $w = $loop->embed ($otherloop, $callback)
772 $w = $loop->embed_ns ($otherloop, $callback)
773 Call the callback when the embedded event loop ($otherloop) has any
774 I/O activity. The $callback should alwas be specified as "undef" in
775 this version of EV, which means the embedded event loop will be
776 managed automatically.
777
778 The "embed_ns" variant doesn't start (activate) the newly created
779 watcher.
780
781PERL SIGNALS
782 While Perl signal handling (%SIG) is not affected by EV, the behaviour
783 with EV is as the same as any other C library: Perl-signals will only be
784 handled when Perl runs, which means your signal handler might be invoked
785 only the next time an event callback is invoked.
786
787 The solution is to use EV signal watchers (see "EV::signal"), which will
788 ensure proper operations with regards to other event watchers.
789
790 If you cannot do this for whatever reason, you can also force a watcher
791 to be called on every event loop iteration by installing a "EV::check"
792 watcher:
793
794 my $async_check = EV::check sub { };
795
796 This ensures that perl gets into control for a short time to handle any
797 pending signals, and also ensures (slightly) slower overall operation.
615 798
616THREADS 799THREADS
617 Threads are not supported by this module in any way. Perl pseudo-threads 800 Threads are not supported by this module in any way. Perl pseudo-threads
618 is evil stuff and must die. As soon as Perl gains real threads I will 801 is evil stuff and must die. As soon as Perl gains real threads I will
619 work on thread support for it. 802 work on thread support for it.
… …
634 817
635 On win32, there is no notion of fork so all this doesn't apply, of 818 On win32, there is no notion of fork so all this doesn't apply, of
636 course. 819 course.
637 820
638SEE ALSO 821SEE ALSO
639 EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event 822 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
640 loop), Coro::EV (efficient coroutines with EV). 823 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
824 with EV), Net::SNMP::EV (asynchronous SNMP).
641 825
642AUTHOR 826AUTHOR
643 Marc Lehmann <schmorp@schmorp.de> 827 Marc Lehmann <schmorp@schmorp.de>
644 http://home.schmorp.de/ 828 http://home.schmorp.de/
645 829

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines