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Revision 1.34 by root, Sun Aug 9 13:30:41 2009 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 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://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
60 details on watcher semantics or some discussion on the available 60 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 61 discussion on the available backends, or how to force a specific backend
62 about in any case because it has much more detailed information. 62 with "LIBEV_FLAGS", or just about in any case because it has much more
63 detailed information.
64
65 This module is very fast and scalable. It is actually so fast that you
66 can use it through the AnyEvent module, stay portable to other event
67 loops (if you don't rely on any watcher types not available through it)
68 and still be faster than with any other event loop currently supported
69 in Perl.
70
71 MODULE EXPORTS
72 This module does not export any symbols.
73
74EVENT LOOPS
75 EV supports multiple event loops: There is a single "default event loop"
76 that can handle everything including signals and child watchers, and any
77 number of "dynamic event loops" that can use different backends (with
78 various limitations), but no child and signal watchers.
79
80 You do not have to do anything to create the default event loop: When
81 the module is loaded a suitable backend is selected on the premise of
82 selecting a working backend (which for example rules out kqueue on most
83 BSDs). Modules should, unless they have "special needs" always use the
84 default loop as this is fastest (perl-wise), best supported by other
85 modules (e.g. AnyEvent or Coro) and most portable event loop.
86
87 For specific programs you can create additional event loops dynamically.
88
89 If you want to take advantage of kqueue (which often works properly for
90 sockets only) even though the default loop doesn't enable it, you can
91 *embed* a kqueue loop into the default loop: running the default loop
92 will then also service the kqueue loop to some extent. See the example
93 in the section about embed watchers for an example on how to achieve
94 that.
95
96 $loop = new EV::Loop [$flags]
97 Create a new event loop as per the specified flags. Please refer to
98 the "ev_loop_new ()" function description in the libev documentation
99 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
100 ONS>, or locally-installed as EV::libev manpage) for more info.
101
102 The loop will automatically be destroyed when it is no longer
103 referenced by any watcher and the loop object goes out of scope.
104
105 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
106 is recommended, as only the default event loop is protected by this
107 module. If you *are* embedding this loop in the default loop, this
108 is not necessary, as "EV::embed" automatically does the right thing
109 on fork.
110
111 $loop->loop_fork
112 Must be called after a fork in the child, before entering or
113 continuing the event loop. An alternative is to use
114 "EV::FLAG_FORKCHECK" which calls this function automatically, at
115 some performance loss (refer to the libev documentation).
116
117 $loop->loop_verify
118 Calls "ev_verify" to make internal consistency checks (for debugging
119 libev) and abort the program if any data structures were found to be
120 corrupted.
121
122 $loop = EV::default_loop [$flags]
123 Return the default loop (which is a singleton object). Since this
124 module already creates the default loop with default flags,
125 specifying flags here will not have any effect unless you destroy
126 the default loop first, which isn't supported. So in short: don't do
127 it, and if you break it, you get to keep the pieces.
63 128
64BASIC INTERFACE 129BASIC INTERFACE
65 $EV::DIED 130 $EV::DIED
66 Must contain a reference to a function that is called when a 131 Must contain a reference to a function that is called when a
67 callback throws an exception (with $@ containing thr error). The 132 callback throws an exception (with $@ containing the error). The
68 default prints an informative message and continues. 133 default prints an informative message and continues.
69 134
70 If this callback throws an exception it will be silently ignored. 135 If this callback throws an exception it will be silently ignored.
136
137 $flags = EV::supported_backends
138 $flags = EV::recommended_backends
139 $flags = EV::embeddable_backends
140 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
141 this instance of EV, the set of recommended backends (supposed to be
142 good) for this platform and the set of embeddable backends (see
143 EMBED WATCHERS).
144
145 EV::sleep $seconds
146 Block the process for the given number of (fractional) seconds.
71 147
72 $time = EV::time 148 $time = EV::time
73 Returns the current time in (fractional) seconds since the epoch. 149 Returns the current time in (fractional) seconds since the epoch.
74 150
75 $time = EV::now 151 $time = EV::now
152 $time = $loop->now
76 Returns the time the last event loop iteration has been started. 153 Returns the time the last event loop iteration has been started.
77 This is the time that (relative) timers are based on, and refering 154 This is the time that (relative) timers are based on, and referring
78 to it is usually faster then calling EV::time. 155 to it is usually faster then calling EV::time.
79 156
80 $method = EV::method 157 EV::now_update
158 $loop->now_update
159 Establishes the current time by querying the kernel, updating the
160 time returned by "EV::now" in the progress. This is a costly
161 operation and is usually done automatically within "EV::loop".
162
163 This function is rarely useful, but when some event callback runs
164 for a very long time without entering the event loop, updating
165 libev's idea of the current time is a good idea.
166
167 EV::suspend
168 $loop->suspend
169 EV::resume
170 $loop->resume
171 These two functions suspend and resume a loop, for use when the loop
172 is not used for a while and timeouts should not be processed.
173
174 A typical use case would be an interactive program such as a game:
175 When the user presses "^Z" to suspend the game and resumes it an
176 hour later it would be best to handle timeouts as if no time had
177 actually passed while the program was suspended. This can be
178 achieved by calling "suspend" in your "SIGTSTP" handler, sending
179 yourself a "SIGSTOP" and calling "resume" directly afterwards to
180 resume timer processing.
181
182 Effectively, all "timer" watchers will be delayed by the time spend
183 between "suspend" and "resume", and all "periodic" watchers will be
184 rescheduled (that is, they will lose any events that would have
185 occured while suspended).
186
187 After calling "suspend" you must not call *any* function on the
188 given loop other than "resume", and you must not call "resume"
189 without a previous call to "suspend".
190
191 Calling "suspend"/"resume" has the side effect of updating the event
192 loop time (see "now_update").
193
194 $backend = EV::backend
195 $backend = $loop->backend
81 Returns an integer describing the backend used by libev 196 Returns an integer describing the backend used by libev
82 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 197 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
83 198
84 EV::loop [$flags] 199 EV::loop [$flags]
200 $loop->loop ([$flags])
85 Begin checking for events and calling callbacks. It returns when a 201 Begin checking for events and calling callbacks. It returns when a
86 callback calls EV::unloop. 202 callback calls EV::unloop.
87 203
88 The $flags argument can be one of the following: 204 The $flags argument can be one of the following:
89 205
90 0 as above 206 0 as above
91 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 207 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
92 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 208 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
93 209
94 EV::unloop [$how] 210 EV::unloop [$how]
211 $loop->unloop ([$how])
95 When called with no arguments or an argument of EV::UNLOOP_ONE, 212 When called with no arguments or an argument of EV::UNLOOP_ONE,
96 makes the innermost call to EV::loop return. 213 makes the innermost call to EV::loop return.
97 214
98 When called with an argument of EV::UNLOOP_ALL, all calls to 215 When called with an argument of EV::UNLOOP_ALL, all calls to
99 EV::loop will return as fast as possible. 216 EV::loop will return as fast as possible.
100 217
101 $count = EV::loop_count 218 $count = EV::loop_count
219 $count = $loop->loop_count
102 Return the number of times the event loop has polled for new events. 220 Return the number of times the event loop has polled for new events.
103 Sometiems useful as a generation counter. 221 Sometimes useful as a generation counter.
104 222
105 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 223 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
224 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
106 This function rolls together an I/O and a timer watcher for a single 225 This function rolls together an I/O and a timer watcher for a single
107 one-shot event without the need for managing a watcher object. 226 one-shot event without the need for managing a watcher object.
108 227
109 If $fh_or_undef is a filehandle or file descriptor, then $events 228 If $fh_or_undef is a filehandle or file descriptor, then $events
110 must be a bitset containing either "EV::READ", "EV::WRITE" or 229 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
115 If timeout is "undef" or negative, then there will be no timeout. 234 If timeout is "undef" or negative, then there will be no timeout.
116 Otherwise a EV::timer with this value will be started. 235 Otherwise a EV::timer with this value will be started.
117 236
118 When an error occurs or either the timeout or I/O watcher triggers, 237 When an error occurs or either the timeout or I/O watcher triggers,
119 then the callback will be called with the received event set (in 238 then the callback will be called with the received event set (in
120 general you can expect it to be a combination of "EV:ERROR", 239 general you can expect it to be a combination of "EV::ERROR",
121 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 240 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
122 241
123 EV::once doesn't return anything: the watchers stay active till 242 EV::once doesn't return anything: the watchers stay active till
124 either of them triggers, then they will be stopped and freed, and 243 either of them triggers, then they will be stopped and freed, and
125 the callback invoked. 244 the callback invoked.
126 245
246 EV::feed_fd_event ($fd, $revents)
247 $loop->feed_fd_event ($fd, $revents)
248 Feed an event on a file descriptor into EV. EV will react to this
249 call as if the readyness notifications specified by $revents (a
250 combination of "EV::READ" and "EV::WRITE") happened on the file
251 descriptor $fd.
252
253 EV::feed_signal_event ($signal)
254 Feed a signal event into EV. EV will react to this call as if the
255 signal specified by $signal had occured.
256
257 EV::set_io_collect_interval $time
258 $loop->set_io_collect_interval ($time)
259 EV::set_timeout_collect_interval $time
260 $loop->set_timeout_collect_interval ($time)
261 These advanced functions set the minimum block interval when polling
262 for I/O events and the minimum wait interval for timer events. See
263 the libev documentation at
264 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
265 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
266 detailed discussion.
267
268 $count = EV::pending_count
269 $count = $loop->pending_count
270 Returns the number of currently pending watchers.
271
272 EV::invoke_pending
273 $loop->invoke_pending
274 Invoke all currently pending watchers.
275
127 WATCHER OBJECTS 276WATCHER OBJECTS
128 A watcher is an object that gets created to record your interest in some 277 A watcher is an object that gets created to record your interest in some
129 event. For instance, if you want to wait for STDIN to become readable, 278 event. For instance, if you want to wait for STDIN to become readable,
130 you would create an EV::io watcher for that: 279 you would create an EV::io watcher for that:
131 280
132 my $watcher = EV::io *STDIN, EV::READ, sub { 281 my $watcher = EV::io *STDIN, EV::READ, sub {
133 my ($watcher, $revents) = @_; 282 my ($watcher, $revents) = @_;
134 warn "yeah, STDIN should not be readable without blocking!\n" 283 warn "yeah, STDIN should now be readable without blocking!\n"
135 }; 284 };
136 285
137 All watchers can be active (waiting for events) or inactive (paused). 286 All watchers can be active (waiting for events) or inactive (paused).
138 Only active watchers will have their callbacks invoked. All callbacks 287 Only active watchers will have their callbacks invoked. All callbacks
139 will be called with at least two arguments: the watcher and a bitmask of 288 will be called with at least two arguments: the watcher and a bitmask of
140 received events. 289 received events.
141 290
142 Each watcher type has its associated bit in revents, so you can use the 291 Each watcher type has its associated bit in revents, so you can use the
143 same callback for multiple watchers. The event mask is named after the 292 same callback for multiple watchers. The event mask is named after the
144 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 293 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
145 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O 294 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
146 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 295 events (which can set both EV::READ and EV::WRITE bits), and EV::timer
147 (which uses EV::TIMEOUT). 296 (which uses EV::TIMEOUT).
148 297
149 In the rare case where one wants to create a watcher but not start it at 298 In the rare case where one wants to create a watcher but not start it at
… …
202 The default priority of any newly-created watcher is 0. 351 The default priority of any newly-created watcher is 0.
203 352
204 Note that the priority semantics have not yet been fleshed out and 353 Note that the priority semantics have not yet been fleshed out and
205 are subject to almost certain change. 354 are subject to almost certain change.
206 355
207 $w->trigger ($revents) 356 $w->invoke ($revents)
208 Call the callback *now* with the given event mask. 357 Call the callback *now* with the given event mask.
358
359 $w->feed_event ($revents)
360 Feed some events on this watcher into EV. EV will react to this call
361 as if the watcher had received the given $revents mask.
362
363 $revents = $w->clear_pending
364 If the watcher is pending, this function clears its pending status
365 and returns its $revents bitset (as if its callback was invoked). If
366 the watcher isn't pending it does nothing and returns 0.
209 367
210 $previous_state = $w->keepalive ($bool) 368 $previous_state = $w->keepalive ($bool)
211 Normally, "EV::loop" will return when there are no active watchers 369 Normally, "EV::loop" will return when there are no active watchers
212 (which is a "deadlock" because no progress can be made anymore). 370 (which is a "deadlock" because no progress can be made anymore).
213 This is convinient because it allows you to start your watchers (and 371 This is convinient because it allows you to start your watchers (and
214 your jobs), call "EV::loop" once and when it returns you know that 372 your jobs), call "EV::loop" once and when it returns you know that
215 all your jobs are finished (or they forgot to register some watchers 373 all your jobs are finished (or they forgot to register some watchers
216 for their task :). 374 for their task :).
217 375
218 Sometimes, however, this gets in your way, for example when you the 376 Sometimes, however, this gets in your way, for example when the
219 module that calls "EV::loop" (usually the main program) is not the 377 module that calls "EV::loop" (usually the main program) is not the
220 same module as a long-living watcher (for example a DNS client 378 same module as a long-living watcher (for example a DNS client
221 module written by somebody else even). Then you might want any 379 module written by somebody else even). Then you might want any
222 outstanding requests to be handled, but you would not want to keep 380 outstanding requests to be handled, but you would not want to keep
223 "EV::loop" from returning just because you happen to have this 381 "EV::loop" from returning just because you happen to have this
… …
225 383
226 In this case you can clear the keepalive status, which means that 384 In this case you can clear the keepalive status, which means that
227 even though your watcher is active, it won't keep "EV::loop" from 385 even though your watcher is active, it won't keep "EV::loop" from
228 returning. 386 returning.
229 387
230 The initial value for keepalive is true (enabled), and you cna 388 The initial value for keepalive is true (enabled), and you can
231 change it any time. 389 change it any time.
232 390
233 Example: Register an I/O watcher for some UDP socket but do not keep 391 Example: Register an I/O watcher for some UDP socket but do not keep
234 the event loop from running just because of that watcher. 392 the event loop from running just because of that watcher.
235 393
236 my $udp_socket = ... 394 my $udp_socket = ...
237 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 395 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
238 $udp_watcher->keepalive (0); 396 $udp_watcher->keepalive (0);
239 397
398 $loop = $w->loop
399 Return the loop that this watcher is attached to.
400
240 WATCHER TYPES 401WATCHER TYPES
241 Each of the following subsections describes a single watcher type. 402 Each of the following subsections describes a single watcher type.
242 403
243 I/O WATCHERS - is this file descriptor readable or writable? 404 I/O WATCHERS - is this file descriptor readable or writable?
244 $w = EV::io $fileno_or_fh, $eventmask, $callback 405 $w = EV::io $fileno_or_fh, $eventmask, $callback
245 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 406 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
407 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
408 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
246 As long as the returned watcher object is alive, call the $callback 409 As long as the returned watcher object is alive, call the $callback
247 when at least one of events specified in $eventmask occurs. 410 when at least one of events specified in $eventmask occurs.
248 411
249 The $eventmask can be one or more of these constants ORed together: 412 The $eventmask can be one or more of these constants ORed together:
250 413
… …
267 Returns the previously set event mask and optionally set a new one. 430 Returns the previously set event mask and optionally set a new one.
268 431
269 TIMER WATCHERS - relative and optionally repeating timeouts 432 TIMER WATCHERS - relative and optionally repeating timeouts
270 $w = EV::timer $after, $repeat, $callback 433 $w = EV::timer $after, $repeat, $callback
271 $w = EV::timer_ns $after, $repeat, $callback 434 $w = EV::timer_ns $after, $repeat, $callback
435 $w = $loop->timer ($after, $repeat, $callback)
436 $w = $loop->timer_ns ($after, $repeat, $callback)
272 Calls the callback after $after seconds (which may be fractional). 437 Calls the callback after $after seconds (which may be fractional).
273 If $repeat is non-zero, the timer will be restarted (with the 438 If $repeat is non-zero, the timer will be restarted (with the
274 $repeat value as $after) after the callback returns. 439 $repeat value as $after) after the callback returns.
275 440
276 This means that the callback would be called roughly after $after 441 This means that the callback would be called roughly after $after
… …
312 method on the timeout. 477 method on the timeout.
313 478
314 PERIODIC WATCHERS - to cron or not to cron? 479 PERIODIC WATCHERS - to cron or not to cron?
315 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 480 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
316 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 481 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
482 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
483 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
317 Similar to EV::timer, but is not based on relative timeouts but on 484 Similar to EV::timer, but is not based on relative timeouts but on
318 absolute times. Apart from creating "simple" timers that trigger 485 absolute times. Apart from creating "simple" timers that trigger
319 "at" the specified time, it can also be used for non-drifting 486 "at" the specified time, it can also be used for non-drifting
320 absolute timers and more complex, cron-like, setups that are not 487 absolute timers and more complex, cron-like, setups that are not
321 adversely affected by time jumps (i.e. when the system clock is 488 adversely affected by time jumps (i.e. when the system clock is
322 changed by explicit date -s or other means such as ntpd). It is also 489 changed by explicit date -s or other means such as ntpd). It is also
323 the most complex watcher type in EV. 490 the most complex watcher type in EV.
324 491
325 It has three distinct "modes": 492 It has three distinct "modes":
326 493
327 * absolute timer ($interval = $reschedule_cb = 0) 494 * absolute timer ($interval = $reschedule_cb = 0)
495
328 This time simply fires at the wallclock time $at and doesn't 496 This time simply fires at the wallclock time $at and doesn't
329 repeat. It will not adjust when a time jump occurs, that is, if 497 repeat. It will not adjust when a time jump occurs, that is, if
330 it is to be run at January 1st 2011 then it will run when the 498 it is to be run at January 1st 2011 then it will run when the
331 system time reaches or surpasses this time. 499 system time reaches or surpasses this time.
332 500
333 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 501 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
502
334 In this mode the watcher will always be scheduled to time out at 503 In this mode the watcher will always be scheduled to time out at
335 the next "$at + N * $interval" time (for some integer N) and 504 the next "$at + N * $interval" time (for some integer N) and
336 then repeat, regardless of any time jumps. 505 then repeat, regardless of any time jumps.
337 506
338 This can be used to create timers that do not drift with respect 507 This can be used to create timers that do not drift with respect
… …
347 Another way to think about it (for the mathematically inclined) 516 Another way to think about it (for the mathematically inclined)
348 is that EV::periodic will try to run the callback in this mode 517 is that EV::periodic will try to run the callback in this mode
349 at the next possible time where "$time = $at (mod $interval)", 518 at the next possible time where "$time = $at (mod $interval)",
350 regardless of any time jumps. 519 regardless of any time jumps.
351 520
352 * manual reschedule mode ($reschedule_cb = coderef) 521 * manual reschedule mode ($reschedule_cb = coderef)
522
353 In this mode $interval and $at are both being ignored. Instead, 523 In this mode $interval and $at are both being ignored. Instead,
354 each time the periodic watcher gets scheduled, the reschedule 524 each time the periodic watcher gets scheduled, the reschedule
355 callback ($reschedule_cb) will be called with the watcher as 525 callback ($reschedule_cb) will be called with the watcher as
356 first, and the current time as second argument. 526 first, and the current time as second argument.
357 527
358 *This callback MUST NOT stop or destroy this or any other 528 *This callback MUST NOT stop or destroy this or any other
529 periodic watcher, ever, and MUST NOT call any event loop
359 periodic watcher, ever*. If you need to stop it, return 1e30 and 530 functions or methods*. If you need to stop it, return 1e30 and
360 stop it afterwards. 531 stop it afterwards. You may create and start a "EV::prepare"
532 watcher for this task.
361 533
362 It must return the next time to trigger, based on the passed 534 It must return the next time to trigger, based on the passed
363 time value (that is, the lowest time value larger than to the 535 time value (that is, the lowest time value larger than or equal
364 second argument). It will usually be called just before the 536 to to the second argument). It will usually be called just
365 callback will be triggered, but might be called at other times, 537 before the callback will be triggered, but might be called at
366 too. 538 other times, too.
367 539
368 This can be used to create very complex timers, such as a timer 540 This can be used to create very complex timers, such as a timer
369 that triggers on each midnight, local time (actually 24 hours 541 that triggers on each midnight, local time (actually 24 hours
370 after the last midnight, to keep the example simple. If you know 542 after the last midnight, to keep the example simple. If you know
371 a way to do it correctly in about the same space (without 543 a way to do it correctly in about the same space (without
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389 be called at any time. 561 be called at any time.
390 562
391 $w->again 563 $w->again
392 Simply stops and starts the watcher again. 564 Simply stops and starts the watcher again.
393 565
566 $time = $w->at
567 Return the time that the watcher is expected to trigger next.
568
394 SIGNAL WATCHERS - signal me when a signal gets signalled! 569 SIGNAL WATCHERS - signal me when a signal gets signalled!
395 $w = EV::signal $signal, $callback 570 $w = EV::signal $signal, $callback
396 $w = EV::signal_ns $signal, $callback 571 $w = EV::signal_ns $signal, $callback
572 $w = $loop->signal ($signal, $callback)
573 $w = $loop->signal_ns ($signal, $callback)
397 Call the callback when $signal is received (the signal can be 574 Call the callback when $signal is received (the signal can be
398 specified by number or by name, just as with "kill" or %SIG). 575 specified by number or by name, just as with "kill" or %SIG).
576
577 Only one event loop can grab a given signal - attempting to grab the
578 same signal from two EV loops will crash the program immediately or
579 cause data corruption.
399 580
400 EV will grab the signal for the process (the kernel only allows one 581 EV will grab the signal for the process (the kernel only allows one
401 component to receive a signal at a time) when you start a signal 582 component to receive a signal at a time) when you start a signal
402 watcher, and removes it again when you stop it. Perl does the same 583 watcher, and removes it again when you stop it. Perl does the same
403 when you add/remove callbacks to %SIG, so watch out. 584 when you add/remove callbacks to %SIG, so watch out.
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415 $old_signum = $w->signal ($new_signal) 596 $old_signum = $w->signal ($new_signal)
416 Returns the previously set signal (always as a number not name) and 597 Returns the previously set signal (always as a number not name) and
417 optionally set a new one. 598 optionally set a new one.
418 599
419 CHILD WATCHERS - watch out for process status changes 600 CHILD WATCHERS - watch out for process status changes
420 $w = EV::child $pid, $callback 601 $w = EV::child $pid, $trace, $callback
421 $w = EV::child_ns $pid, $callback 602 $w = EV::child_ns $pid, $trace, $callback
603 $w = $loop->child ($pid, $trace, $callback)
604 $w = $loop->child_ns ($pid, $trace, $callback)
422 Call the callback when a status change for pid $pid (or any pid if 605 Call the callback when a status change for pid $pid (or any pid if
423 $pid is 0) has been received. More precisely: when the process 606 $pid is 0) has been received (a status change happens when the
607 process terminates or is killed, or, when trace is true,
608 additionally when it is stopped or continued). More precisely: when
424 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 609 the process receives a "SIGCHLD", EV will fetch the outstanding
425 for all changed/zombie children and call the callback. 610 exit/wait status for all changed/zombie children and call the
611 callback.
426 612
427 It is valid (and fully supported) to install a child watcher after a 613 It is valid (and fully supported) to install a child watcher after a
428 child has exited but before the event loop has started its next 614 child has exited but before the event loop has started its next
429 iteration (for example, first you "fork", then the new child process 615 iteration (for example, first you "fork", then the new child process
430 might exit, and only then do you install a child watcher in the 616 might exit, and only then do you install a child watcher in the
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437 be called. 623 be called.
438 624
439 The "child_ns" variant doesn't start (activate) the newly created 625 The "child_ns" variant doesn't start (activate) the newly created
440 watcher. 626 watcher.
441 627
442 $w->set ($pid) 628 $w->set ($pid, $trace)
443 Reconfigures the watcher, see the constructor above for details. Can 629 Reconfigures the watcher, see the constructor above for details. Can
444 be called at any time. 630 be called at any time.
445 631
446 $current_pid = $w->pid 632 $current_pid = $w->pid
447 $old_pid = $w->pid ($new_pid)
448 Returns the previously set process id and optionally set a new one. 633 Returns the previously set process id and optionally set a new one.
449 634
450 $exit_status = $w->rstatus 635 $exit_status = $w->rstatus
451 Return the exit/wait status (as returned by waitpid, see the waitpid 636 Return the exit/wait status (as returned by waitpid, see the waitpid
452 entry in perlfunc). 637 entry in perlfunc).
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456 a watcher for all pids). 641 a watcher for all pids).
457 642
458 STAT WATCHERS - did the file attributes just change? 643 STAT WATCHERS - did the file attributes just change?
459 $w = EV::stat $path, $interval, $callback 644 $w = EV::stat $path, $interval, $callback
460 $w = EV::stat_ns $path, $interval, $callback 645 $w = EV::stat_ns $path, $interval, $callback
646 $w = $loop->stat ($path, $interval, $callback)
647 $w = $loop->stat_ns ($path, $interval, $callback)
461 Call the callback when a file status change has been detected on 648 Call the callback when a file status change has been detected on
462 $path. The $path does not need to exist, changing from "path exists" 649 $path. The $path does not need to exist, changing from "path exists"
463 to "path does not exist" is a status change like any other. 650 to "path does not exist" is a status change like any other.
464 651
465 The $interval is a recommended polling interval for systems where 652 The $interval is a recommended polling interval for systems where
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525 Can be used to query the actual interval used. 712 Can be used to query the actual interval used.
526 713
527 IDLE WATCHERS - when you've got nothing better to do... 714 IDLE WATCHERS - when you've got nothing better to do...
528 $w = EV::idle $callback 715 $w = EV::idle $callback
529 $w = EV::idle_ns $callback 716 $w = EV::idle_ns $callback
717 $w = $loop->idle ($callback)
718 $w = $loop->idle_ns ($callback)
530 Call the callback when there are no other pending watchers of the 719 Call the callback when there are no other pending watchers of the
531 same or higher priority (excluding check, prepare and other idle 720 same or higher priority (excluding check, prepare and other idle
532 watchers of the same or lower priority, of course). They are called 721 watchers of the same or lower priority, of course). They are called
533 idle watchers because when the watcher is the highest priority 722 idle watchers because when the watcher is the highest priority
534 pending event in the process, the process is considered to be idle 723 pending event in the process, the process is considered to be idle
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550 watcher. 739 watcher.
551 740
552 PREPARE WATCHERS - customise your event loop! 741 PREPARE WATCHERS - customise your event loop!
553 $w = EV::prepare $callback 742 $w = EV::prepare $callback
554 $w = EV::prepare_ns $callback 743 $w = EV::prepare_ns $callback
744 $w = $loop->prepare ($callback)
745 $w = $loop->prepare_ns ($callback)
555 Call the callback just before the process would block. You can still 746 Call the callback just before the process would block. You can still
556 create/modify any watchers at this point. 747 create/modify any watchers at this point.
557 748
558 See the EV::check watcher, below, for explanations and an example. 749 See the EV::check watcher, below, for explanations and an example.
559 750
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561 watcher. 752 watcher.
562 753
563 CHECK WATCHERS - customise your event loop even more! 754 CHECK WATCHERS - customise your event loop even more!
564 $w = EV::check $callback 755 $w = EV::check $callback
565 $w = EV::check_ns $callback 756 $w = EV::check_ns $callback
757 $w = $loop->check ($callback)
758 $w = $loop->check_ns ($callback)
566 Call the callback just after the process wakes up again (after it 759 Call the callback just after the process wakes up again (after it
567 has gathered events), but before any other callbacks have been 760 has gathered events), but before any other callbacks have been
568 invoked. 761 invoked.
569 762
570 This is used to integrate other event-based software into the EV 763 This is used to integrate other event-based software into the EV
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606 # make the dispatcher handle any new stuff 799 # make the dispatcher handle any new stuff
607 ... not shown 800 ... not shown
608 }; 801 };
609 802
610 The callbacks of the created watchers will not be called as the 803 The callbacks of the created watchers will not be called as the
611 watchers are destroyed before this cna happen (remember EV::check 804 watchers are destroyed before this can happen (remember EV::check
612 gets called first). 805 gets called first).
613 806
614 The "check_ns" variant doesn't start (activate) the newly created 807 The "check_ns" variant doesn't start (activate) the newly created
615 watcher. 808 watcher.
616 809
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619 is done before the event loop blocks next and before "check" watchers 812 is done before the event loop blocks next and before "check" watchers
620 are being called, and only in the child after the fork. 813 are being called, and only in the child after the fork.
621 814
622 $w = EV::fork $callback 815 $w = EV::fork $callback
623 $w = EV::fork_ns $callback 816 $w = EV::fork_ns $callback
817 $w = $loop->fork ($callback)
818 $w = $loop->fork_ns ($callback)
624 Call the callback before the event loop is resumed in the child 819 Call the callback before the event loop is resumed in the child
625 process after a fork. 820 process after a fork.
626 821
627 The "fork_ns" variant doesn't start (activate) the newly created 822 The "fork_ns" variant doesn't start (activate) the newly created
628 watcher. 823 watcher.
824
825 EMBED WATCHERS - when one backend isn't enough...
826 This is a rather advanced watcher type that lets you embed one event
827 loop into another (currently only IO events are supported in the
828 embedded loop, other types of watchers might be handled in a delayed or
829 incorrect fashion and must not be used).
830
831 See the libev documentation at
832 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
833 _when_one_backend_> (locally installed as EV::libev) for more details.
834
835 In short, this watcher is most useful on BSD systems without working
836 kqueue to still be able to handle a large number of sockets:
837
838 my $socket_loop;
839
840 # check wether we use SELECT or POLL _and_ KQUEUE is supported
841 if (
842 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
843 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
844 ) {
845 # use kqueue for sockets
846 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
847 }
848
849 # use the default loop otherwise
850 $socket_loop ||= EV::default_loop;
851
852 $w = EV::embed $otherloop[, $callback]
853 $w = EV::embed_ns $otherloop[, $callback]
854 $w = $loop->embed ($otherloop[, $callback])
855 $w = $loop->embed_ns ($otherloop[, $callback])
856 Call the callback when the embedded event loop ($otherloop) has any
857 I/O activity. The $callback is optional: if it is missing, then the
858 embedded event loop will be managed automatically (which is
859 recommended), otherwise you have to invoke "sweep" yourself.
860
861 The "embed_ns" variant doesn't start (activate) the newly created
862 watcher.
863
864 ASYNC WATCHERS - how to wake up another event loop
865 Async watchers are provided by EV, but have little use in perl directly,
866 as perl neither supports threads running in parallel nor direct access
867 to signal handlers or other contexts where they could be of value.
868
869 It is, however, possible to use them from the XS level.
870
871 Please see the libev documentation for further details.
872
873 $w = EV::async $callback
874 $w = EV::async_ns $callback
875 $w->send
876 $bool = $w->async_pending
629 877
630PERL SIGNALS 878PERL SIGNALS
631 While Perl signal handling (%SIG) is not affected by EV, the behaviour 879 While Perl signal handling (%SIG) is not affected by EV, the behaviour
632 with EV is as the same as any other C library: Perl-signals will only be 880 with EV is as the same as any other C library: Perl-signals will only be
633 handled when Perl runs, which means your signal handler might be invoked 881 handled when Perl runs, which means your signal handler might be invoked
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640 to be called on every event loop iteration by installing a "EV::check" 888 to be called on every event loop iteration by installing a "EV::check"
641 watcher: 889 watcher:
642 890
643 my $async_check = EV::check sub { }; 891 my $async_check = EV::check sub { };
644 892
645 This ensures that perl shortly gets into control for a short time, and 893 This ensures that perl gets into control for a short time to handle any
646 also ensures slower overall operation. 894 pending signals, and also ensures (slightly) slower overall operation.
647 895
648THREADS 896ITHREADS
649 Threads are not supported by this module in any way. Perl pseudo-threads 897 Ithreads are not supported by this module in any way. Perl
650 is evil stuff and must die. As soon as Perl gains real threads I will 898 pseudo-threads is evil stuff and must die. Real threads as provided by
651 work on thread support for it. 899 Coro are fully supported (and enhanced support is available via
900 Coro::EV).
652 901
653FORK 902FORK
654 Most of the "improved" event delivering mechanisms of modern operating 903 Most of the "improved" event delivering mechanisms of modern operating
655 systems have quite a few problems with fork(2) (to put it bluntly: it is 904 systems have quite a few problems with fork(2) (to put it bluntly: it is
656 not supported and usually destructive). Libev makes it possible to work 905 not supported and usually destructive). Libev makes it possible to work
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666 915
667 On win32, there is no notion of fork so all this doesn't apply, of 916 On win32, there is no notion of fork so all this doesn't apply, of
668 course. 917 course.
669 918
670SEE ALSO 919SEE ALSO
671 EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event 920 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
672 loop), Coro::EV (efficient coroutines with EV). 921 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
922 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
923 agnostic and portable event driven programming.
673 924
674AUTHOR 925AUTHOR
675 Marc Lehmann <schmorp@schmorp.de> 926 Marc Lehmann <schmorp@schmorp.de>
676 http://home.schmorp.de/ 927 http://home.schmorp.de/
677 928

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