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Revision 1.36 by root, Thu Oct 21 02:46:59 2010 UTC

1NAME 1NAME
2 EV - perl interface to libev, a high performance full-featured event 2 EV - perl interface to libev, a high performance full-featured event
3 loop 3 loop
4 4
5SYNOPSIS 5SYNOPSIS
6 use EV; 6 use EV;
7
8 # TIMERS
9
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
7 38
8 # TIMERS 39 my $w = EV::child 666, 0, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
9 43
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
38
39 my $w = EV::child 666, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
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
55BEFORE YOU START USING THIS MODULE
56 If you only need timer, I/O, signal, child and idle watchers and not the
57 advanced functionality of this module, consider using AnyEvent instead,
58 specifically the simplified API described in AE.
59
60 When used with EV as backend, the AE API is as fast as the native EV
61 API, but your programs/modules will still run with many other event
62 loops.
54 63
55DESCRIPTION 64DESCRIPTION
56 This module provides an interface to libev 65 This module provides an interface to libev
57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation 66 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
58 below is comprehensive, one might also consult the documentation of 67 below is comprehensive, one might also consult the documentation of
59 libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle 68 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
60 details on watcher semantics or some discussion on the available 69 perldoc EV::libev) for more subtle details on watcher semantics or some
61 backends, or how to force a specific backend with "LIBEV_FLAGS", or just 70 discussion on the available backends, or how to force a specific backend
62 about in any case because it has much more detailed information. 71 with "LIBEV_FLAGS", or just about in any case because it has much more
72 detailed information.
73
74 This module is very fast and scalable. It is actually so fast that you
75 can use it through the AnyEvent module, stay portable to other event
76 loops (if you don't rely on any watcher types not available through it)
77 and still be faster than with any other event loop currently supported
78 in Perl.
79
80 MODULE EXPORTS
81 This module does not export any symbols.
63 82
64EVENT LOOPS 83EVENT LOOPS
65 EV supports multiple event loops: There is a single "default event loop" 84 EV supports multiple event loops: There is a single "default event loop"
66 that can handle everything including signals and child watchers, and any 85 that can handle everything including signals and child watchers, and any
67 number of "dynamic event loops" that can use different backends (with 86 number of "dynamic event loops" that can use different backends (with
… …
72 selecting a working backend (which for example rules out kqueue on most 91 selecting a working backend (which for example rules out kqueue on most
73 BSDs). Modules should, unless they have "special needs" always use the 92 BSDs). Modules should, unless they have "special needs" always use the
74 default loop as this is fastest (perl-wise), best supported by other 93 default loop as this is fastest (perl-wise), best supported by other
75 modules (e.g. AnyEvent or Coro) and most portable event loop. 94 modules (e.g. AnyEvent or Coro) and most portable event loop.
76 95
77 For specific programs you cna create additional event loops dynamically. 96 For specific programs you can create additional event loops dynamically.
78 97
98 If you want to take advantage of kqueue (which often works properly for
99 sockets only) even though the default loop doesn't enable it, you can
100 *embed* a kqueue loop into the default loop: running the default loop
101 will then also service the kqueue loop to some extent. See the example
102 in the section about embed watchers for an example on how to achieve
103 that.
104
79 $loop = new EV::loop [$flags] 105 $loop = new EV::Loop [$flags]
80 Create a new event loop as per the specified flags. Please refer to 106 Create a new event loop as per the specified flags. Please refer to
81 the "ev_loop_new ()" function description in the libev documentation 107 the "ev_loop_new ()" function description in the libev documentation
82 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI 108 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
83 ONS>) for more info. 109 ONS>, or locally-installed as EV::libev manpage) for more info.
84 110
85 The loop will automatically be destroyed when it is no longer 111 The loop will automatically be destroyed when it is no longer
86 referenced by any watcher and the loop object goes out of scope. 112 referenced by any watcher and the loop object goes out of scope.
87 113
88 Using "EV::FLAG_FORKCHECK" is recommended, as only the default event 114 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
89 loop is protected by this module. 115 is recommended, as only the default event loop is protected by this
116 module. If you *are* embedding this loop in the default loop, this
117 is not necessary, as "EV::embed" automatically does the right thing
118 on fork.
90 119
91 $loop->loop_fork 120 $loop->loop_fork
92 Must be called after a fork in the child, before entering or 121 Must be called after a fork in the child, before entering or
93 continuing the event loop. An alternative is to use 122 continuing the event loop. An alternative is to use
94 "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at 123 "EV::FLAG_FORKCHECK" which calls this function automatically, at
95 some performance loss (refer to the libev documentation). 124 some performance loss (refer to the libev documentation).
125
126 $loop->loop_verify
127 Calls "ev_verify" to make internal consistency checks (for debugging
128 libev) and abort the program if any data structures were found to be
129 corrupted.
130
131 $loop = EV::default_loop [$flags]
132 Return the default loop (which is a singleton object). Since this
133 module already creates the default loop with default flags,
134 specifying flags here will not have any effect unless you destroy
135 the default loop first, which isn't supported. So in short: don't do
136 it, and if you break it, you get to keep the pieces.
96 137
97BASIC INTERFACE 138BASIC INTERFACE
98 $EV::DIED 139 $EV::DIED
99 Must contain a reference to a function that is called when a 140 Must contain a reference to a function that is called when a
100 callback throws an exception (with $@ containing the error). The 141 callback throws an exception (with $@ containing the error). The
101 default prints an informative message and continues. 142 default prints an informative message and continues.
102 143
103 If this callback throws an exception it will be silently ignored. 144 If this callback throws an exception it will be silently ignored.
104 145
146 $flags = EV::supported_backends
147 $flags = EV::recommended_backends
148 $flags = EV::embeddable_backends
149 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
150 this instance of EV, the set of recommended backends (supposed to be
151 good) for this platform and the set of embeddable backends (see
152 EMBED WATCHERS).
153
154 EV::sleep $seconds
155 Block the process for the given number of (fractional) seconds.
156
105 $time = EV::time 157 $time = EV::time
106 Returns the current time in (fractional) seconds since the epoch. 158 Returns the current time in (fractional) seconds since the epoch.
107 159
108 $time = EV::now 160 $time = EV::now
109 $time = $loop->now 161 $time = $loop->now
110 Returns the time the last event loop iteration has been started. 162 Returns the time the last event loop iteration has been started.
111 This is the time that (relative) timers are based on, and refering 163 This is the time that (relative) timers are based on, and referring
112 to it is usually faster then calling EV::time. 164 to it is usually faster then calling EV::time.
165
166 EV::now_update
167 $loop->now_update
168 Establishes the current time by querying the kernel, updating the
169 time returned by "EV::now" in the progress. This is a costly
170 operation and is usually done automatically within "EV::loop".
171
172 This function is rarely useful, but when some event callback runs
173 for a very long time without entering the event loop, updating
174 libev's idea of the current time is a good idea.
175
176 EV::suspend
177 $loop->suspend
178 EV::resume
179 $loop->resume
180 These two functions suspend and resume a loop, for use when the loop
181 is not used for a while and timeouts should not be processed.
182
183 A typical use case would be an interactive program such as a game:
184 When the user presses "^Z" to suspend the game and resumes it an
185 hour later it would be best to handle timeouts as if no time had
186 actually passed while the program was suspended. This can be
187 achieved by calling "suspend" in your "SIGTSTP" handler, sending
188 yourself a "SIGSTOP" and calling "resume" directly afterwards to
189 resume timer processing.
190
191 Effectively, all "timer" watchers will be delayed by the time spend
192 between "suspend" and "resume", and all "periodic" watchers will be
193 rescheduled (that is, they will lose any events that would have
194 occured while suspended).
195
196 After calling "suspend" you must not call *any* function on the
197 given loop other than "resume", and you must not call "resume"
198 without a previous call to "suspend".
199
200 Calling "suspend"/"resume" has the side effect of updating the event
201 loop time (see "now_update").
113 202
114 $backend = EV::backend 203 $backend = EV::backend
115 $backend = $loop->backend 204 $backend = $loop->backend
116 Returns an integer describing the backend used by libev 205 Returns an integer describing the backend used by libev
117 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 206 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
118 207
119 EV::loop [$flags] 208 EV::loop [$flags]
120 $loop->loop ([$flags]) 209 $loop->loop ([$flags])
121 Begin checking for events and calling callbacks. It returns when a 210 Begin checking for events and calling callbacks. It returns when a
122 callback calls EV::unloop. 211 callback calls EV::unloop.
… …
136 EV::loop will return as fast as possible. 225 EV::loop will return as fast as possible.
137 226
138 $count = EV::loop_count 227 $count = EV::loop_count
139 $count = $loop->loop_count 228 $count = $loop->loop_count
140 Return the number of times the event loop has polled for new events. 229 Return the number of times the event loop has polled for new events.
141 Sometiems useful as a generation counter. 230 Sometimes useful as a generation counter.
142 231
143 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 232 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
144 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) 233 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
145 This function rolls together an I/O and a timer watcher for a single 234 This function rolls together an I/O and a timer watcher for a single
146 one-shot event without the need for managing a watcher object. 235 one-shot event without the need for managing a watcher object.
… …
155 Otherwise a EV::timer with this value will be started. 244 Otherwise a EV::timer with this value will be started.
156 245
157 When an error occurs or either the timeout or I/O watcher triggers, 246 When an error occurs or either the timeout or I/O watcher triggers,
158 then the callback will be called with the received event set (in 247 then the callback will be called with the received event set (in
159 general you can expect it to be a combination of "EV::ERROR", 248 general you can expect it to be a combination of "EV::ERROR",
160 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 249 "EV::READ", "EV::WRITE" and "EV::TIMER").
161 250
162 EV::once doesn't return anything: the watchers stay active till 251 EV::once doesn't return anything: the watchers stay active till
163 either of them triggers, then they will be stopped and freed, and 252 either of them triggers, then they will be stopped and freed, and
164 the callback invoked. 253 the callback invoked.
165 254
… …
172 261
173 EV::feed_signal_event ($signal) 262 EV::feed_signal_event ($signal)
174 Feed a signal event into EV. EV will react to this call as if the 263 Feed a signal event into EV. EV will react to this call as if the
175 signal specified by $signal had occured. 264 signal specified by $signal had occured.
176 265
266 EV::set_io_collect_interval $time
267 $loop->set_io_collect_interval ($time)
268 EV::set_timeout_collect_interval $time
269 $loop->set_timeout_collect_interval ($time)
270 These advanced functions set the minimum block interval when polling
271 for I/O events and the minimum wait interval for timer events. See
272 the libev documentation at
273 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
274 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
275 detailed discussion.
276
277 $count = EV::pending_count
278 $count = $loop->pending_count
279 Returns the number of currently pending watchers.
280
281 EV::invoke_pending
282 $loop->invoke_pending
283 Invoke all currently pending watchers.
284
177WATCHER OBJECTS 285WATCHER OBJECTS
178 A watcher is an object that gets created to record your interest in some 286 A watcher is an object that gets created to record your interest in some
179 event. For instance, if you want to wait for STDIN to become readable, 287 event. For instance, if you want to wait for STDIN to become readable,
180 you would create an EV::io watcher for that: 288 you would create an EV::io watcher for that:
181 289
182 my $watcher = EV::io *STDIN, EV::READ, sub { 290 my $watcher = EV::io *STDIN, EV::READ, sub {
183 my ($watcher, $revents) = @_; 291 my ($watcher, $revents) = @_;
184 warn "yeah, STDIN should now be readable without blocking!\n" 292 warn "yeah, STDIN should now be readable without blocking!\n"
185 }; 293 };
186 294
187 All watchers can be active (waiting for events) or inactive (paused). 295 All watchers can be active (waiting for events) or inactive (paused).
188 Only active watchers will have their callbacks invoked. All callbacks 296 Only active watchers will have their callbacks invoked. All callbacks
189 will be called with at least two arguments: the watcher and a bitmask of 297 will be called with at least two arguments: the watcher and a bitmask of
190 received events. 298 received events.
191 299
192 Each watcher type has its associated bit in revents, so you can use the 300 Each watcher type has its associated bit in revents, so you can use the
193 same callback for multiple watchers. The event mask is named after the 301 same callback for multiple watchers. The event mask is named after the
194 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 302 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
195 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O 303 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
196 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 304 events (which can set both EV::READ and EV::WRITE bits).
197 (which uses EV::TIMEOUT).
198 305
199 In the rare case where one wants to create a watcher but not start it at 306 In the rare case where one wants to create a watcher but not start it at
200 the same time, each constructor has a variant with a trailing "_ns" in 307 the same time, each constructor has a variant with a trailing "_ns" in
201 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 308 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
202 309
… …
267 the watcher isn't pending it does nothing and returns 0. 374 the watcher isn't pending it does nothing and returns 0.
268 375
269 $previous_state = $w->keepalive ($bool) 376 $previous_state = $w->keepalive ($bool)
270 Normally, "EV::loop" will return when there are no active watchers 377 Normally, "EV::loop" will return when there are no active watchers
271 (which is a "deadlock" because no progress can be made anymore). 378 (which is a "deadlock" because no progress can be made anymore).
272 This is convinient because it allows you to start your watchers (and 379 This is convenient because it allows you to start your watchers (and
273 your jobs), call "EV::loop" once and when it returns you know that 380 your jobs), call "EV::loop" once and when it returns you know that
274 all your jobs are finished (or they forgot to register some watchers 381 all your jobs are finished (or they forgot to register some watchers
275 for their task :). 382 for their task :).
276 383
277 Sometimes, however, this gets in your way, for example when the 384 Sometimes, however, this gets in your way, for example when the
… …
284 391
285 In this case you can clear the keepalive status, which means that 392 In this case you can clear the keepalive status, which means that
286 even though your watcher is active, it won't keep "EV::loop" from 393 even though your watcher is active, it won't keep "EV::loop" from
287 returning. 394 returning.
288 395
289 The initial value for keepalive is true (enabled), and you cna 396 The initial value for keepalive is true (enabled), and you can
290 change it any time. 397 change it any time.
291 398
292 Example: Register an I/O watcher for some UDP socket but do not keep 399 Example: Register an I/O watcher for some UDP socket but do not keep
293 the event loop from running just because of that watcher. 400 the event loop from running just because of that watcher.
294 401
295 my $udp_socket = ... 402 my $udp_socket = ...
296 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 403 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
297 $1000udp_watcher->keepalive (0); 404 $udp_watcher->keepalive (0);
298 405
299 $loop = $w->loop 406 $loop = $w->loop
300 Return the loop that this watcher is attached to. 407 Return the loop that this watcher is attached to.
301 408
302WATCHER TYPES 409WATCHER TYPES
… …
390 changed by explicit date -s or other means such as ntpd). It is also 497 changed by explicit date -s or other means such as ntpd). It is also
391 the most complex watcher type in EV. 498 the most complex watcher type in EV.
392 499
393 It has three distinct "modes": 500 It has three distinct "modes":
394 501
395 * absolute timer ($interval = $reschedule_cb = 0) 502 * absolute timer ($interval = $reschedule_cb = 0)
503
396 This time simply fires at the wallclock time $at and doesn't 504 This time simply fires at the wallclock time $at and doesn't
397 repeat. It will not adjust when a time jump occurs, that is, if 505 repeat. It will not adjust when a time jump occurs, that is, if
398 it is to be run at January 1st 2011 then it will run when the 506 it is to be run at January 1st 2011 then it will run when the
399 system time reaches or surpasses this time. 507 system time reaches or surpasses this time.
400 508
401 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 509 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
510
402 In this mode the watcher will always be scheduled to time out at 511 In this mode the watcher will always be scheduled to time out at
403 the next "$at + N * $interval" time (for some integer N) and 512 the next "$at + N * $interval" time (for some integer N) and
404 then repeat, regardless of any time jumps. 513 then repeat, regardless of any time jumps.
405 514
406 This can be used to create timers that do not drift with respect 515 This can be used to create timers that do not drift with respect
… …
415 Another way to think about it (for the mathematically inclined) 524 Another way to think about it (for the mathematically inclined)
416 is that EV::periodic will try to run the callback in this mode 525 is that EV::periodic will try to run the callback in this mode
417 at the next possible time where "$time = $at (mod $interval)", 526 at the next possible time where "$time = $at (mod $interval)",
418 regardless of any time jumps. 527 regardless of any time jumps.
419 528
420 * manual reschedule mode ($reschedule_cb = coderef) 529 * manual reschedule mode ($reschedule_cb = coderef)
530
421 In this mode $interval and $at are both being ignored. Instead, 531 In this mode $interval and $at are both being ignored. Instead,
422 each time the periodic watcher gets scheduled, the reschedule 532 each time the periodic watcher gets scheduled, the reschedule
423 callback ($reschedule_cb) will be called with the watcher as 533 callback ($reschedule_cb) will be called with the watcher as
424 first, and the current time as second argument. 534 first, and the current time as second argument.
425 535
426 *This callback MUST NOT stop or destroy this or any other 536 *This callback MUST NOT stop or destroy this or any other
537 periodic watcher, ever, and MUST NOT call any event loop
427 periodic watcher, ever*. If you need to stop it, return 1e30 and 538 functions or methods*. If you need to stop it, return 1e30 and
428 stop it afterwards. 539 stop it afterwards. You may create and start a "EV::prepare"
540 watcher for this task.
429 541
430 It must return the next time to trigger, based on the passed 542 It must return the next time to trigger, based on the passed
431 time value (that is, the lowest time value larger than to the 543 time value (that is, the lowest time value larger than or equal
432 second argument). It will usually be called just before the 544 to to the second argument). It will usually be called just
433 callback will be triggered, but might be called at other times, 545 before the callback will be triggered, but might be called at
434 too. 546 other times, too.
435 547
436 This can be used to create very complex timers, such as a timer 548 This can be used to create very complex timers, such as a timer
437 that triggers on each midnight, local time (actually 24 hours 549 that triggers on each midnight, local time (actually 24 hours
438 after the last midnight, to keep the example simple. If you know 550 after the last midnight, to keep the example simple. If you know
439 a way to do it correctly in about the same space (without 551 a way to do it correctly in about the same space (without
… …
463 Return the time that the watcher is expected to trigger next. 575 Return the time that the watcher is expected to trigger next.
464 576
465 SIGNAL WATCHERS - signal me when a signal gets signalled! 577 SIGNAL WATCHERS - signal me when a signal gets signalled!
466 $w = EV::signal $signal, $callback 578 $w = EV::signal $signal, $callback
467 $w = EV::signal_ns $signal, $callback 579 $w = EV::signal_ns $signal, $callback
580 $w = $loop->signal ($signal, $callback)
581 $w = $loop->signal_ns ($signal, $callback)
468 Call the callback when $signal is received (the signal can be 582 Call the callback when $signal is received (the signal can be
469 specified by number or by name, just as with "kill" or %SIG). 583 specified by number or by name, just as with "kill" or %SIG).
584
585 Only one event loop can grab a given signal - attempting to grab the
586 same signal from two EV loops will crash the program immediately or
587 cause data corruption.
470 588
471 EV will grab the signal for the process (the kernel only allows one 589 EV will grab the signal for the process (the kernel only allows one
472 component to receive a signal at a time) when you start a signal 590 component to receive a signal at a time) when you start a signal
473 watcher, and removes it again when you stop it. Perl does the same 591 watcher, and removes it again when you stop it. Perl does the same
474 when you add/remove callbacks to %SIG, so watch out. 592 when you add/remove callbacks to %SIG, so watch out.
… …
486 $old_signum = $w->signal ($new_signal) 604 $old_signum = $w->signal ($new_signal)
487 Returns the previously set signal (always as a number not name) and 605 Returns the previously set signal (always as a number not name) and
488 optionally set a new one. 606 optionally set a new one.
489 607
490 CHILD WATCHERS - watch out for process status changes 608 CHILD WATCHERS - watch out for process status changes
491 $w = EV::child $pid, $callback 609 $w = EV::child $pid, $trace, $callback
492 $w = EV::child_ns $pid, $callback 610 $w = EV::child_ns $pid, $trace, $callback
493 $w = $loop->child ($pid, $callback) 611 $w = $loop->child ($pid, $trace, $callback)
494 $w = $loop->child_ns ($pid, $callback) 612 $w = $loop->child_ns ($pid, $trace, $callback)
495 Call the callback when a status change for pid $pid (or any pid if 613 Call the callback when a status change for pid $pid (or any pid if
496 $pid is 0) has been received. More precisely: when the process 614 $pid is 0) has been received (a status change happens when the
615 process terminates or is killed, or, when trace is true,
616 additionally when it is stopped or continued). More precisely: when
497 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 617 the process receives a "SIGCHLD", EV will fetch the outstanding
498 for all changed/zombie children and call the callback. 618 exit/wait status for all changed/zombie children and call the
619 callback.
499 620
500 It is valid (and fully supported) to install a child watcher after a 621 It is valid (and fully supported) to install a child watcher after a
501 child has exited but before the event loop has started its next 622 child has exited but before the event loop has started its next
502 iteration (for example, first you "fork", then the new child process 623 iteration (for example, first you "fork", then the new child process
503 might exit, and only then do you install a child watcher in the 624 might exit, and only then do you install a child watcher in the
… …
510 be called. 631 be called.
511 632
512 The "child_ns" variant doesn't start (activate) the newly created 633 The "child_ns" variant doesn't start (activate) the newly created
513 watcher. 634 watcher.
514 635
515 $w->set ($pid) 636 $w->set ($pid, $trace)
516 Reconfigures the watcher, see the constructor above for details. Can 637 Reconfigures the watcher, see the constructor above for details. Can
517 be called at any time. 638 be called at any time.
518 639
519 $current_pid = $w->pid 640 $current_pid = $w->pid
520 $old_pid = $w->pid ($new_pid)
521 Returns the previously set process id and optionally set a new one. 641 Returns the previously set process id and optionally set a new one.
522 642
523 $exit_status = $w->rstatus 643 $exit_status = $w->rstatus
524 Return the exit/wait status (as returned by waitpid, see the waitpid 644 Return the exit/wait status (as returned by waitpid, see the waitpid
525 entry in perlfunc). 645 entry in perlfunc).
… …
687 # make the dispatcher handle any new stuff 807 # make the dispatcher handle any new stuff
688 ... not shown 808 ... not shown
689 }; 809 };
690 810
691 The callbacks of the created watchers will not be called as the 811 The callbacks of the created watchers will not be called as the
692 watchers are destroyed before this cna happen (remember EV::check 812 watchers are destroyed before this can happen (remember EV::check
693 gets called first). 813 gets called first).
694 814
695 The "check_ns" variant doesn't start (activate) the newly created 815 The "check_ns" variant doesn't start (activate) the newly created
696 watcher. 816 watcher.
697 817
… …
708 process after a fork. 828 process after a fork.
709 829
710 The "fork_ns" variant doesn't start (activate) the newly created 830 The "fork_ns" variant doesn't start (activate) the newly created
711 watcher. 831 watcher.
712 832
833 EMBED WATCHERS - when one backend isn't enough...
834 This is a rather advanced watcher type that lets you embed one event
835 loop into another (currently only IO events are supported in the
836 embedded loop, other types of watchers might be handled in a delayed or
837 incorrect fashion and must not be used).
838
839 See the libev documentation at
840 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
841 _when_one_backend_> (locally installed as EV::libev) for more details.
842
843 In short, this watcher is most useful on BSD systems without working
844 kqueue to still be able to handle a large number of sockets:
845
846 my $socket_loop;
847
848 # check wether we use SELECT or POLL _and_ KQUEUE is supported
849 if (
850 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
851 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
852 ) {
853 # use kqueue for sockets
854 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
855 }
856
857 # use the default loop otherwise
858 $socket_loop ||= EV::default_loop;
859
860 $w = EV::embed $otherloop[, $callback]
861 $w = EV::embed_ns $otherloop[, $callback]
862 $w = $loop->embed ($otherloop[, $callback])
863 $w = $loop->embed_ns ($otherloop[, $callback])
864 Call the callback when the embedded event loop ($otherloop) has any
865 I/O activity. The $callback is optional: if it is missing, then the
866 embedded event loop will be managed automatically (which is
867 recommended), otherwise you have to invoke "sweep" yourself.
868
869 The "embed_ns" variant doesn't start (activate) the newly created
870 watcher.
871
872 ASYNC WATCHERS - how to wake up another event loop
873 Async watchers are provided by EV, but have little use in perl directly,
874 as perl neither supports threads running in parallel nor direct access
875 to signal handlers or other contexts where they could be of value.
876
877 It is, however, possible to use them from the XS level.
878
879 Please see the libev documentation for further details.
880
881 $w = EV::async $callback
882 $w = EV::async_ns $callback
883 $w->send
884 $bool = $w->async_pending
885
713PERL SIGNALS 886PERL SIGNALS
714 While Perl signal handling (%SIG) is not affected by EV, the behaviour 887 While Perl signal handling (%SIG) is not affected by EV, the behaviour
715 with EV is as the same as any other C library: Perl-signals will only be 888 with EV is as the same as any other C library: Perl-signals will only be
716 handled when Perl runs, which means your signal handler might be invoked 889 handled when Perl runs, which means your signal handler might be invoked
717 only the next time an event callback is invoked. 890 only the next time an event callback is invoked.
… …
726 my $async_check = EV::check sub { }; 899 my $async_check = EV::check sub { };
727 900
728 This ensures that perl gets into control for a short time to handle any 901 This ensures that perl gets into control for a short time to handle any
729 pending signals, and also ensures (slightly) slower overall operation. 902 pending signals, and also ensures (slightly) slower overall operation.
730 903
731THREADS 904ITHREADS
732 Threads are not supported by this module in any way. Perl pseudo-threads 905 Ithreads are not supported by this module in any way. Perl
733 is evil stuff and must die. As soon as Perl gains real threads I will 906 pseudo-threads is evil stuff and must die. Real threads as provided by
734 work on thread support for it. 907 Coro are fully supported (and enhanced support is available via
908 Coro::EV).
735 909
736FORK 910FORK
737 Most of the "improved" event delivering mechanisms of modern operating 911 Most of the "improved" event delivering mechanisms of modern operating
738 systems have quite a few problems with fork(2) (to put it bluntly: it is 912 systems have quite a few problems with fork(2) (to put it bluntly: it is
739 not supported and usually destructive). Libev makes it possible to work 913 not supported and usually destructive). Libev makes it possible to work
… …
751 course. 925 course.
752 926
753SEE ALSO 927SEE ALSO
754 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event 928 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
755 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines 929 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
756 with EV), Net::SNMP::EV (asynchronous SNMP). 930 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
931 agnostic and portable event driven programming.
757 932
758AUTHOR 933AUTHOR
759 Marc Lehmann <schmorp@schmorp.de> 934 Marc Lehmann <schmorp@schmorp.de>
760 http://home.schmorp.de/ 935 http://home.schmorp.de/
761 936

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