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Revision 1.40 by root, Thu Jan 19 17:55:23 2012 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::run; # 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::run EV::RUN_ONCE; # 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::run EV::RUN_NOWAIT; # try to handle same events, but do not block
54
55BEFORE YOU START USING THIS MODULE
56 If you only need timer, I/O, signal, child and idle watchers and not the
57 advanced functionality of this module, consider using AnyEvent instead,
58 specifically the simplified API described in AE.
59
60 When used with EV as backend, the AE API is as fast as the native EV
61 API, but your programs/modules will still run with many other event
62 loops.
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 PORTING FROM EV 3.X to 4.X
81 EV version 4 introduces a number of incompatible changes summarised
82 here. According to the depreciation strategy used by libev, there is a
83 compatibility layer in place so programs should continue to run
84 unchanged (the XS interface lacks this layer, so programs using that one
85 need to be updated).
86
87 This compatibility layer will be switched off in some future release.
88
89 All changes relevant to Perl are renames of symbols, functions and
90 methods:
91
92 EV::loop => EV::run
93 EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
94 EV::LOOP_ONESHOT => EV::RUN_ONCE
95
96 EV::unloop => EV::break
97 EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
98 EV::UNLOOP_ONE => EV::BREAK_ONE
99 EV::UNLOOP_ALL => EV::BREAK_ALL
100
101 EV::TIMEOUT => EV::TIMER
102
103 EV::loop_count => EV::iteration
104 EV::loop_depth => EV::depth
105 EV::loop_verify => EV::verify
106
107 The loop object methods corresponding to the functions above have been
108 similarly renamed.
109
110 MODULE EXPORTS
111 This module does not export any symbols.
63 112
64EVENT LOOPS 113EVENT LOOPS
65 EV supports multiple event loops: There is a single "default event loop" 114 EV supports multiple event loops: There is a single "default event loop"
66 that can handle everything including signals and child watchers, and any 115 that can handle everything including signals and child watchers, and any
67 number of "dynamic event loops" that can use different backends (with 116 number of "dynamic event loops" that can use different backends (with
… …
72 selecting a working backend (which for example rules out kqueue on most 121 selecting a working backend (which for example rules out kqueue on most
73 BSDs). Modules should, unless they have "special needs" always use the 122 BSDs). Modules should, unless they have "special needs" always use the
74 default loop as this is fastest (perl-wise), best supported by other 123 default loop as this is fastest (perl-wise), best supported by other
75 modules (e.g. AnyEvent or Coro) and most portable event loop. 124 modules (e.g. AnyEvent or Coro) and most portable event loop.
76 125
77 For specific programs you cna create additional event loops dynamically. 126 For specific programs you can create additional event loops dynamically.
78 127
128 If you want to take advantage of kqueue (which often works properly for
129 sockets only) even though the default loop doesn't enable it, you can
130 *embed* a kqueue loop into the default loop: running the default loop
131 will then also service the kqueue loop to some extent. See the example
132 in the section about embed watchers for an example on how to achieve
133 that.
134
79 $loop = new EV::loop [$flags] 135 $loop = new EV::Loop [$flags]
80 Create a new event loop as per the specified flags. Please refer to 136 Create a new event loop as per the specified flags. Please refer to
81 the "ev_loop_new ()" function description in the libev documentation 137 the "ev_loop_new ()" function description in the libev documentation
82 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI 138 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
83 ONS>) for more info. 139 ONS>, or locally-installed as EV::libev manpage) for more info.
84 140
85 The loop will automatically be destroyed when it is no longer 141 The loop will automatically be destroyed when it is no longer
86 referenced by any watcher and the loop object goes out of scope. 142 referenced by any watcher and the loop object goes out of scope.
87 143
88 Using "EV::FLAG_FORKCHECK" is recommended, as only the default event 144 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
89 loop is protected by this module. 145 is recommended, as only the default event loop is protected by this
146 module. If you *are* embedding this loop in the default loop, this
147 is not necessary, as "EV::embed" automatically does the right thing
148 on fork.
90 149
91 $loop->loop_fork 150 $loop->loop_fork
92 Must be called after a fork in the child, before entering or 151 Must be called after a fork in the child, before entering or
93 continuing the event loop. An alternative is to use 152 continuing the event loop. An alternative is to use
94 "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at 153 "EV::FLAG_FORKCHECK" which calls this function automatically, at
95 some performance loss (refer to the libev documentation). 154 some performance loss (refer to the libev documentation).
155
156 $loop->verify
157 Calls "ev_verify" to make internal consistency checks (for debugging
158 libev) and abort the program if any data structures were found to be
159 corrupted.
160
161 $loop = EV::default_loop [$flags]
162 Return the default loop (which is a singleton object). Since this
163 module already creates the default loop with default flags,
164 specifying flags here will not have any effect unless you destroy
165 the default loop first, which isn't supported. So in short: don't do
166 it, and if you break it, you get to keep the pieces.
96 167
97BASIC INTERFACE 168BASIC INTERFACE
98 $EV::DIED 169 $EV::DIED
99 Must contain a reference to a function that is called when a 170 Must contain a reference to a function that is called when a
100 callback throws an exception (with $@ containing the error). The 171 callback throws an exception (with $@ containing the error). The
101 default prints an informative message and continues. 172 default prints an informative message and continues.
102 173
103 If this callback throws an exception it will be silently ignored. 174 If this callback throws an exception it will be silently ignored.
104 175
176 $flags = EV::supported_backends
177 $flags = EV::recommended_backends
178 $flags = EV::embeddable_backends
179 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
180 this instance of EV, the set of recommended backends (supposed to be
181 good) for this platform and the set of embeddable backends (see
182 EMBED WATCHERS).
183
184 EV::sleep $seconds
185 Block the process for the given number of (fractional) seconds.
186
105 $time = EV::time 187 $time = EV::time
106 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
107 189
108 $time = EV::now 190 $time = EV::now
109 $time = $loop->now 191 $time = $loop->now
110 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
111 This is the time that (relative) timers are based on, and refering 193 This is the time that (relative) timers are based on, and referring
112 to it is usually faster then calling EV::time. 194 to it is usually faster then calling EV::time.
195
196 EV::now_update
197 $loop->now_update
198 Establishes the current time by querying the kernel, updating the
199 time returned by "EV::now" in the progress. This is a costly
200 operation and is usually done automatically within "EV::loop".
201
202 This function is rarely useful, but when some event callback runs
203 for a very long time without entering the event loop, updating
204 libev's idea of the current time is a good idea.
205
206 EV::suspend
207 $loop->suspend
208 EV::resume
209 $loop->resume
210 These two functions suspend and resume a loop, for use when the loop
211 is not used for a while and timeouts should not be processed.
212
213 A typical use case would be an interactive program such as a game:
214 When the user presses "^Z" to suspend the game and resumes it an
215 hour later it would be best to handle timeouts as if no time had
216 actually passed while the program was suspended. This can be
217 achieved by calling "suspend" in your "SIGTSTP" handler, sending
218 yourself a "SIGSTOP" and calling "resume" directly afterwards to
219 resume timer processing.
220
221 Effectively, all "timer" watchers will be delayed by the time spend
222 between "suspend" and "resume", and all "periodic" watchers will be
223 rescheduled (that is, they will lose any events that would have
224 occured while suspended).
225
226 After calling "suspend" you must not call *any* function on the
227 given loop other than "resume", and you must not call "resume"
228 without a previous call to "suspend".
229
230 Calling "suspend"/"resume" has the side effect of updating the event
231 loop time (see "now_update").
113 232
114 $backend = EV::backend 233 $backend = EV::backend
115 $backend = $loop->backend 234 $backend = $loop->backend
116 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
117 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
118 237
119 EV::loop [$flags] 238 EV::run [$flags]
120 $loop->loop ([$flags]) 239 $loop->run ([$flags])
121 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
122 callback calls EV::unloop. 241 callback calls EV::unloop.
123 242
124 The $flags argument can be one of the following: 243 The $flags argument can be one of the following:
125 244
126 0 as above 245 0 as above
127 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 246 EV::RUN_ONCE block at most once (wait, but do not loop)
128 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 247 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
129 248
130 EV::unloop [$how] 249 EV::break [$how]
131 $loop->unloop ([$how]) 250 $loop->break ([$how])
132 When called with no arguments or an argument of EV::UNLOOP_ONE, 251 When called with no arguments or an argument of EV::BREAK_ONE, makes
133 makes the innermost call to EV::loop return. 252 the innermost call to EV::loop return.
134 253
135 When called with an argument of EV::UNLOOP_ALL, all calls to 254 When called with an argument of EV::BREAK_ALL, all calls to EV::loop
136 EV::loop will return as fast as possible. 255 will return as fast as possible.
137 256
138 $count = EV::loop_count 257 When called with an argument of EV::BREAK_CANCEL, any pending break
139 $count = $loop->loop_count 258 will be cancelled.
259
260 $count = EV::iteration
261 $count = $loop->iteration
140 Return the number of times the event loop has polled for new events. 262 Return the number of times the event loop has polled for new events.
141 Sometiems useful as a generation counter. 263 Sometimes useful as a generation counter.
142 264
143 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 265 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
144 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) 266 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
145 This function rolls together an I/O and a timer watcher for a single 267 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. 268 one-shot event without the need for managing a watcher object.
… …
155 Otherwise a EV::timer with this value will be started. 277 Otherwise a EV::timer with this value will be started.
156 278
157 When an error occurs or either the timeout or I/O watcher triggers, 279 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 280 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", 281 general you can expect it to be a combination of "EV::ERROR",
160 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 282 "EV::READ", "EV::WRITE" and "EV::TIMER").
161 283
162 EV::once doesn't return anything: the watchers stay active till 284 EV::once doesn't return anything: the watchers stay active till
163 either of them triggers, then they will be stopped and freed, and 285 either of them triggers, then they will be stopped and freed, and
164 the callback invoked. 286 the callback invoked.
165 287
166 EV::feed_fd_event ($fd, $revents) 288 EV::feed_fd_event $fd, $revents
167 $loop->feed_fd_event ($fd, $revents) 289 $loop->feed_fd_event ($fd, $revents)
168 Feed an event on a file descriptor into EV. EV will react to this 290 Feed an event on a file descriptor into EV. EV will react to this
169 call as if the readyness notifications specified by $revents (a 291 call as if the readyness notifications specified by $revents (a
170 combination of "EV::READ" and "EV::WRITE") happened on the file 292 combination of "EV::READ" and "EV::WRITE") happened on the file
171 descriptor $fd. 293 descriptor $fd.
172 294
173 EV::feed_signal_event ($signal) 295 EV::feed_signal_event $signal
174 Feed a signal event into EV. EV will react to this call as if the 296 Feed a signal event into the default loop. EV will react to this
175 signal specified by $signal had occured. 297 call as if the signal specified by $signal had occured.
298
299 EV::feed_signal $signal
300 Feed a signal event into EV - unlike "EV::feed_signal_event", this
301 works regardless of which loop has registered the signal, and is
302 mainly useful fro custom signal implementations.
303
304 EV::set_io_collect_interval $time
305 $loop->set_io_collect_interval ($time)
306 EV::set_timeout_collect_interval $time
307 $loop->set_timeout_collect_interval ($time)
308 These advanced functions set the minimum block interval when polling
309 for I/O events and the minimum wait interval for timer events. See
310 the libev documentation at
311 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
312 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
313 detailed discussion.
314
315 $count = EV::pending_count
316 $count = $loop->pending_count
317 Returns the number of currently pending watchers.
318
319 EV::invoke_pending
320 $loop->invoke_pending
321 Invoke all currently pending watchers.
176 322
177WATCHER OBJECTS 323WATCHER OBJECTS
178 A watcher is an object that gets created to record your interest in some 324 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, 325 event. For instance, if you want to wait for STDIN to become readable,
180 you would create an EV::io watcher for that: 326 you would create an EV::io watcher for that:
181 327
182 my $watcher = EV::io *STDIN, EV::READ, sub { 328 my $watcher = EV::io *STDIN, EV::READ, sub {
183 my ($watcher, $revents) = @_; 329 my ($watcher, $revents) = @_;
184 warn "yeah, STDIN should now be readable without blocking!\n" 330 warn "yeah, STDIN should now be readable without blocking!\n"
185 }; 331 };
186 332
187 All watchers can be active (waiting for events) or inactive (paused). 333 All watchers can be active (waiting for events) or inactive (paused).
188 Only active watchers will have their callbacks invoked. All callbacks 334 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 335 will be called with at least two arguments: the watcher and a bitmask of
190 received events. 336 received events.
191 337
192 Each watcher type has its associated bit in revents, so you can use the 338 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 339 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, 340 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 341 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 342 events (which can set both EV::READ and EV::WRITE bits).
197 (which uses EV::TIMEOUT).
198 343
199 In the rare case where one wants to create a watcher but not start it at 344 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 345 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. 346 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
202 347
… …
267 the watcher isn't pending it does nothing and returns 0. 412 the watcher isn't pending it does nothing and returns 0.
268 413
269 $previous_state = $w->keepalive ($bool) 414 $previous_state = $w->keepalive ($bool)
270 Normally, "EV::loop" will return when there are no active watchers 415 Normally, "EV::loop" will return when there are no active watchers
271 (which is a "deadlock" because no progress can be made anymore). 416 (which is a "deadlock" because no progress can be made anymore).
272 This is convinient because it allows you to start your watchers (and 417 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 418 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 419 all your jobs are finished (or they forgot to register some watchers
275 for their task :). 420 for their task :).
276 421
277 Sometimes, however, this gets in your way, for example when the 422 Sometimes, however, this gets in your way, for example when the
… …
284 429
285 In this case you can clear the keepalive status, which means that 430 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 431 even though your watcher is active, it won't keep "EV::loop" from
287 returning. 432 returning.
288 433
289 The initial value for keepalive is true (enabled), and you cna 434 The initial value for keepalive is true (enabled), and you can
290 change it any time. 435 change it any time.
291 436
292 Example: Register an I/O watcher for some UDP socket but do not keep 437 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. 438 the event loop from running just because of that watcher.
294 439
295 my $udp_socket = ... 440 my $udp_socket = ...
296 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 441 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
297 $1000udp_watcher->keepalive (0); 442 $udp_watcher->keepalive (0);
298 443
299 $loop = $w->loop 444 $loop = $w->loop
300 Return the loop that this watcher is attached to. 445 Return the loop that this watcher is attached to.
301 446
302WATCHER TYPES 447WATCHER TYPES
… …
390 changed by explicit date -s or other means such as ntpd). It is also 535 changed by explicit date -s or other means such as ntpd). It is also
391 the most complex watcher type in EV. 536 the most complex watcher type in EV.
392 537
393 It has three distinct "modes": 538 It has three distinct "modes":
394 539
395 * absolute timer ($interval = $reschedule_cb = 0) 540 * absolute timer ($interval = $reschedule_cb = 0)
541
396 This time simply fires at the wallclock time $at and doesn't 542 This time simply fires at the wallclock time $at and doesn't
397 repeat. It will not adjust when a time jump occurs, that is, if 543 repeat. It will not adjust when a time jump occurs, that is, if
398 it is to be run at January 1st 2011 then it will run when the 544 it is to be run at January 1st 2011 then it will run when the
399 system time reaches or surpasses this time. 545 system time reaches or surpasses this time.
400 546
401 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 547 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
548
402 In this mode the watcher will always be scheduled to time out at 549 In this mode the watcher will always be scheduled to time out at
403 the next "$at + N * $interval" time (for some integer N) and 550 the next "$at + N * $interval" time (for some integer N) and
404 then repeat, regardless of any time jumps. 551 then repeat, regardless of any time jumps.
405 552
406 This can be used to create timers that do not drift with respect 553 This can be used to create timers that do not drift with respect
… …
415 Another way to think about it (for the mathematically inclined) 562 Another way to think about it (for the mathematically inclined)
416 is that EV::periodic will try to run the callback in this mode 563 is that EV::periodic will try to run the callback in this mode
417 at the next possible time where "$time = $at (mod $interval)", 564 at the next possible time where "$time = $at (mod $interval)",
418 regardless of any time jumps. 565 regardless of any time jumps.
419 566
420 * manual reschedule mode ($reschedule_cb = coderef) 567 * manual reschedule mode ($reschedule_cb = coderef)
568
421 In this mode $interval and $at are both being ignored. Instead, 569 In this mode $interval and $at are both being ignored. Instead,
422 each time the periodic watcher gets scheduled, the reschedule 570 each time the periodic watcher gets scheduled, the reschedule
423 callback ($reschedule_cb) will be called with the watcher as 571 callback ($reschedule_cb) will be called with the watcher as
424 first, and the current time as second argument. 572 first, and the current time as second argument.
425 573
426 *This callback MUST NOT stop or destroy this or any other 574 *This callback MUST NOT stop or destroy this or any other
575 periodic watcher, ever, and MUST NOT call any event loop
427 periodic watcher, ever*. If you need to stop it, return 1e30 and 576 functions or methods*. If you need to stop it, return 1e30 and
428 stop it afterwards. 577 stop it afterwards. You may create and start a "EV::prepare"
578 watcher for this task.
429 579
430 It must return the next time to trigger, based on the passed 580 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 581 time value (that is, the lowest time value larger than or equal
432 second argument). It will usually be called just before the 582 to to the second argument). It will usually be called just
433 callback will be triggered, but might be called at other times, 583 before the callback will be triggered, but might be called at
434 too. 584 other times, too.
435 585
436 This can be used to create very complex timers, such as a timer 586 This can be used to create very complex timers, such as a timer
437 that triggers on each midnight, local time (actually 24 hours 587 that triggers on each midnight, local time (actually 24 hours
438 after the last midnight, to keep the example simple. If you know 588 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 589 a way to do it correctly in about the same space (without
… …
463 Return the time that the watcher is expected to trigger next. 613 Return the time that the watcher is expected to trigger next.
464 614
465 SIGNAL WATCHERS - signal me when a signal gets signalled! 615 SIGNAL WATCHERS - signal me when a signal gets signalled!
466 $w = EV::signal $signal, $callback 616 $w = EV::signal $signal, $callback
467 $w = EV::signal_ns $signal, $callback 617 $w = EV::signal_ns $signal, $callback
618 $w = $loop->signal ($signal, $callback)
619 $w = $loop->signal_ns ($signal, $callback)
468 Call the callback when $signal is received (the signal can be 620 Call the callback when $signal is received (the signal can be
469 specified by number or by name, just as with "kill" or %SIG). 621 specified by number or by name, just as with "kill" or %SIG).
622
623 Only one event loop can grab a given signal - attempting to grab the
624 same signal from two EV loops will crash the program immediately or
625 cause data corruption.
470 626
471 EV will grab the signal for the process (the kernel only allows one 627 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 628 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 629 watcher, and removes it again when you stop it. Perl does the same
474 when you add/remove callbacks to %SIG, so watch out. 630 when you add/remove callbacks to %SIG, so watch out.
… …
486 $old_signum = $w->signal ($new_signal) 642 $old_signum = $w->signal ($new_signal)
487 Returns the previously set signal (always as a number not name) and 643 Returns the previously set signal (always as a number not name) and
488 optionally set a new one. 644 optionally set a new one.
489 645
490 CHILD WATCHERS - watch out for process status changes 646 CHILD WATCHERS - watch out for process status changes
491 $w = EV::child $pid, $callback 647 $w = EV::child $pid, $trace, $callback
492 $w = EV::child_ns $pid, $callback 648 $w = EV::child_ns $pid, $trace, $callback
493 $w = $loop->child ($pid, $callback) 649 $w = $loop->child ($pid, $trace, $callback)
494 $w = $loop->child_ns ($pid, $callback) 650 $w = $loop->child_ns ($pid, $trace, $callback)
495 Call the callback when a status change for pid $pid (or any pid if 651 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 652 $pid is 0) has been received (a status change happens when the
653 process terminates or is killed, or, when trace is true,
654 additionally when it is stopped or continued). More precisely: when
497 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 655 the process receives a "SIGCHLD", EV will fetch the outstanding
498 for all changed/zombie children and call the callback. 656 exit/wait status for all changed/zombie children and call the
657 callback.
499 658
500 It is valid (and fully supported) to install a child watcher after a 659 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 660 child has exited but before the event loop has started its next
502 iteration (for example, first you "fork", then the new child process 661 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 662 might exit, and only then do you install a child watcher in the
… …
510 be called. 669 be called.
511 670
512 The "child_ns" variant doesn't start (activate) the newly created 671 The "child_ns" variant doesn't start (activate) the newly created
513 watcher. 672 watcher.
514 673
515 $w->set ($pid) 674 $w->set ($pid, $trace)
516 Reconfigures the watcher, see the constructor above for details. Can 675 Reconfigures the watcher, see the constructor above for details. Can
517 be called at any time. 676 be called at any time.
518 677
519 $current_pid = $w->pid 678 $current_pid = $w->pid
520 $old_pid = $w->pid ($new_pid)
521 Returns the previously set process id and optionally set a new one. 679 Returns the previously set process id and optionally set a new one.
522 680
523 $exit_status = $w->rstatus 681 $exit_status = $w->rstatus
524 Return the exit/wait status (as returned by waitpid, see the waitpid 682 Return the exit/wait status (as returned by waitpid, see the waitpid
525 entry in perlfunc). 683 entry in perlfunc).
… …
646 $w = $loop->check_ns ($callback) 804 $w = $loop->check_ns ($callback)
647 Call the callback just after the process wakes up again (after it 805 Call the callback just after the process wakes up again (after it
648 has gathered events), but before any other callbacks have been 806 has gathered events), but before any other callbacks have been
649 invoked. 807 invoked.
650 808
651 This is used to integrate other event-based software into the EV 809 This can be used to integrate other event-based software into the EV
652 mainloop: You register a prepare callback and in there, you create 810 mainloop: You register a prepare callback and in there, you create
653 io and timer watchers as required by the other software. Here is a 811 io and timer watchers as required by the other software. Here is a
654 real-world example of integrating Net::SNMP (with some details left 812 real-world example of integrating Net::SNMP (with some details left
655 out): 813 out):
656 814
… …
687 # make the dispatcher handle any new stuff 845 # make the dispatcher handle any new stuff
688 ... not shown 846 ... not shown
689 }; 847 };
690 848
691 The callbacks of the created watchers will not be called as the 849 The callbacks of the created watchers will not be called as the
692 watchers are destroyed before this cna happen (remember EV::check 850 watchers are destroyed before this can happen (remember EV::check
693 gets called first). 851 gets called first).
694 852
695 The "check_ns" variant doesn't start (activate) the newly created 853 The "check_ns" variant doesn't start (activate) the newly created
696 watcher. 854 watcher.
855
856 EV::CHECK constant issues
857 Like all other watcher types, there is a bitmask constant for use in
858 $revents and other places. The "EV::CHECK" is special as it has the
859 same name as the "CHECK" sub called by Perl. This doesn't cause big
860 issues on newer perls (beginning with 5.8.9), but it means thatthe
861 constant must be *inlined*, i.e. runtime calls will not work. That
862 means that as long as you always "use EV" and then "EV::CHECK" you
863 are on the safe side.
697 864
698 FORK WATCHERS - the audacity to resume the event loop after a fork 865 FORK WATCHERS - the audacity to resume the event loop after a fork
699 Fork watchers are called when a "fork ()" was detected. The invocation 866 Fork watchers are called when a "fork ()" was detected. The invocation
700 is done before the event loop blocks next and before "check" watchers 867 is done before the event loop blocks next and before "check" watchers
701 are being called, and only in the child after the fork. 868 are being called, and only in the child after the fork.
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708 process after a fork. 875 process after a fork.
709 876
710 The "fork_ns" variant doesn't start (activate) the newly created 877 The "fork_ns" variant doesn't start (activate) the newly created
711 watcher. 878 watcher.
712 879
880 EMBED WATCHERS - when one backend isn't enough...
881 This is a rather advanced watcher type that lets you embed one event
882 loop into another (currently only IO events are supported in the
883 embedded loop, other types of watchers might be handled in a delayed or
884 incorrect fashion and must not be used).
885
886 See the libev documentation at
887 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
888 _when_one_backend_> (locally installed as EV::libev) for more details.
889
890 In short, this watcher is most useful on BSD systems without working
891 kqueue to still be able to handle a large number of sockets:
892
893 my $socket_loop;
894
895 # check wether we use SELECT or POLL _and_ KQUEUE is supported
896 if (
897 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
898 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
899 ) {
900 # use kqueue for sockets
901 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
902 }
903
904 # use the default loop otherwise
905 $socket_loop ||= EV::default_loop;
906
907 $w = EV::embed $otherloop[, $callback]
908 $w = EV::embed_ns $otherloop[, $callback]
909 $w = $loop->embed ($otherloop[, $callback])
910 $w = $loop->embed_ns ($otherloop[, $callback])
911 Call the callback when the embedded event loop ($otherloop) has any
912 I/O activity. The $callback is optional: if it is missing, then the
913 embedded event loop will be managed automatically (which is
914 recommended), otherwise you have to invoke "sweep" yourself.
915
916 The "embed_ns" variant doesn't start (activate) the newly created
917 watcher.
918
919 ASYNC WATCHERS - how to wake up another event loop
920 Async watchers are provided by EV, but have little use in perl directly,
921 as perl neither supports threads running in parallel nor direct access
922 to signal handlers or other contexts where they could be of value.
923
924 It is, however, possible to use them from the XS level.
925
926 Please see the libev documentation for further details.
927
928 $w = EV::async $callback
929 $w = EV::async_ns $callback
930 $w->send
931 $bool = $w->async_pending
932
713PERL SIGNALS 933PERL SIGNALS
714 While Perl signal handling (%SIG) is not affected by EV, the behaviour 934 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 935 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 936 handled when Perl runs, which means your signal handler might be invoked
717 only the next time an event callback is invoked. 937 only the next time an event callback is invoked.
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726 my $async_check = EV::check sub { }; 946 my $async_check = EV::check sub { };
727 947
728 This ensures that perl gets into control for a short time to handle any 948 This ensures that perl gets into control for a short time to handle any
729 pending signals, and also ensures (slightly) slower overall operation. 949 pending signals, and also ensures (slightly) slower overall operation.
730 950
731THREADS 951ITHREADS
732 Threads are not supported by this module in any way. Perl pseudo-threads 952 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 953 pseudo-threads is evil stuff and must die. Real threads as provided by
734 work on thread support for it. 954 Coro are fully supported (and enhanced support is available via
955 Coro::EV).
735 956
736FORK 957FORK
737 Most of the "improved" event delivering mechanisms of modern operating 958 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 959 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 960 not supported and usually destructive). Libev makes it possible to work
… …
749 970
750 On win32, there is no notion of fork so all this doesn't apply, of 971 On win32, there is no notion of fork so all this doesn't apply, of
751 course. 972 course.
752 973
753SEE ALSO 974SEE ALSO
754 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event 975 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
755 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines 976 DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed
756 with EV), Net::SNMP::EV (asynchronous SNMP). 977 Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV
978 (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event
979 driven programming.
757 980
758AUTHOR 981AUTHOR
759 Marc Lehmann <schmorp@schmorp.de> 982 Marc Lehmann <schmorp@schmorp.de>
760 http://home.schmorp.de/ 983 http://home.schmorp.de/
761 984

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