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

Comparing EV/README (file contents):
Revision 1.20 by root, Sat Dec 22 12:05:42 2007 UTC vs.
Revision 1.42 by root, Sat Mar 8 15:51:23 2014 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 $active = EV::run [$flags]
120 $loop->loop ([$flags]) 239 $active = $loop->run ([$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 or the flasg are nonzero (in which case
242 the return value is true) or when there are no active watchers which
243 reference the loop (keepalive is true), in which case the return
244 value will be false. The returnv alue can generally be interpreted
245 as "if true, there is more work left to do".
123 246
124 The $flags argument can be one of the following: 247 The $flags argument can be one of the following:
125 248
126 0 as above 249 0 as above
127 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 250 EV::RUN_ONCE block at most once (wait, but do not loop)
128 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 251 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
129 252
130 EV::unloop [$how] 253 EV::break [$how]
131 $loop->unloop ([$how]) 254 $loop->break ([$how])
132 When called with no arguments or an argument of EV::UNLOOP_ONE, 255 When called with no arguments or an argument of EV::BREAK_ONE, makes
133 makes the innermost call to EV::loop return. 256 the innermost call to EV::loop return.
134 257
135 When called with an argument of EV::UNLOOP_ALL, all calls to 258 When called with an argument of EV::BREAK_ALL, all calls to EV::loop
136 EV::loop will return as fast as possible. 259 will return as fast as possible.
137 260
138 $count = EV::loop_count 261 When called with an argument of EV::BREAK_CANCEL, any pending break
139 $count = $loop->loop_count 262 will be cancelled.
263
264 $count = EV::iteration
265 $count = $loop->iteration
140 Return the number of times the event loop has polled for new events. 266 Return the number of times the event loop has polled for new events.
141 Sometiems useful as a generation counter. 267 Sometimes useful as a generation counter.
142 268
143 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 269 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
144 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) 270 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
145 This function rolls together an I/O and a timer watcher for a single 271 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. 272 one-shot event without the need for managing a watcher object.
… …
155 Otherwise a EV::timer with this value will be started. 281 Otherwise a EV::timer with this value will be started.
156 282
157 When an error occurs or either the timeout or I/O watcher triggers, 283 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 284 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", 285 general you can expect it to be a combination of "EV::ERROR",
160 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 286 "EV::READ", "EV::WRITE" and "EV::TIMER").
161 287
162 EV::once doesn't return anything: the watchers stay active till 288 EV::once doesn't return anything: the watchers stay active till
163 either of them triggers, then they will be stopped and freed, and 289 either of them triggers, then they will be stopped and freed, and
164 the callback invoked. 290 the callback invoked.
165 291
166 EV::feed_fd_event ($fd, $revents) 292 EV::feed_fd_event $fd, $revents
167 $loop->feed_fd_event ($fd, $revents) 293 $loop->feed_fd_event ($fd, $revents)
168 Feed an event on a file descriptor into EV. EV will react to this 294 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 295 call as if the readyness notifications specified by $revents (a
170 combination of "EV::READ" and "EV::WRITE") happened on the file 296 combination of "EV::READ" and "EV::WRITE") happened on the file
171 descriptor $fd. 297 descriptor $fd.
172 298
173 EV::feed_signal_event ($signal) 299 EV::feed_signal_event $signal
174 Feed a signal event into EV. EV will react to this call as if the 300 Feed a signal event into the default loop. EV will react to this
175 signal specified by $signal had occured. 301 call as if the signal specified by $signal had occured.
302
303 EV::feed_signal $signal
304 Feed a signal event into EV - unlike "EV::feed_signal_event", this
305 works regardless of which loop has registered the signal, and is
306 mainly useful fro custom signal implementations.
307
308 EV::set_io_collect_interval $time
309 $loop->set_io_collect_interval ($time)
310 EV::set_timeout_collect_interval $time
311 $loop->set_timeout_collect_interval ($time)
312 These advanced functions set the minimum block interval when polling
313 for I/O events and the minimum wait interval for timer events. See
314 the libev documentation at
315 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
316 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
317 detailed discussion.
318
319 $count = EV::pending_count
320 $count = $loop->pending_count
321 Returns the number of currently pending watchers.
322
323 EV::invoke_pending
324 $loop->invoke_pending
325 Invoke all currently pending watchers.
176 326
177WATCHER OBJECTS 327WATCHER OBJECTS
178 A watcher is an object that gets created to record your interest in some 328 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, 329 event. For instance, if you want to wait for STDIN to become readable,
180 you would create an EV::io watcher for that: 330 you would create an EV::io watcher for that:
181 331
182 my $watcher = EV::io *STDIN, EV::READ, sub { 332 my $watcher = EV::io *STDIN, EV::READ, sub {
183 my ($watcher, $revents) = @_; 333 my ($watcher, $revents) = @_;
184 warn "yeah, STDIN should now be readable without blocking!\n" 334 warn "yeah, STDIN should now be readable without blocking!\n"
185 }; 335 };
186 336
187 All watchers can be active (waiting for events) or inactive (paused). 337 All watchers can be active (waiting for events) or inactive (paused).
188 Only active watchers will have their callbacks invoked. All callbacks 338 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 339 will be called with at least two arguments: the watcher and a bitmask of
190 received events. 340 received events.
191 341
192 Each watcher type has its associated bit in revents, so you can use the 342 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 343 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, 344 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 345 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 346 events (which can set both EV::READ and EV::WRITE bits).
197 (which uses EV::TIMEOUT).
198 347
199 In the rare case where one wants to create a watcher but not start it at 348 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 349 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. 350 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
202 351
… …
267 the watcher isn't pending it does nothing and returns 0. 416 the watcher isn't pending it does nothing and returns 0.
268 417
269 $previous_state = $w->keepalive ($bool) 418 $previous_state = $w->keepalive ($bool)
270 Normally, "EV::loop" will return when there are no active watchers 419 Normally, "EV::loop" will return when there are no active watchers
271 (which is a "deadlock" because no progress can be made anymore). 420 (which is a "deadlock" because no progress can be made anymore).
272 This is convinient because it allows you to start your watchers (and 421 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 422 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 423 all your jobs are finished (or they forgot to register some watchers
275 for their task :). 424 for their task :).
276 425
277 Sometimes, however, this gets in your way, for example when the 426 Sometimes, however, this gets in your way, for example when the
… …
284 433
285 In this case you can clear the keepalive status, which means that 434 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 435 even though your watcher is active, it won't keep "EV::loop" from
287 returning. 436 returning.
288 437
289 The initial value for keepalive is true (enabled), and you cna 438 The initial value for keepalive is true (enabled), and you can
290 change it any time. 439 change it any time.
291 440
292 Example: Register an I/O watcher for some UDP socket but do not keep 441 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. 442 the event loop from running just because of that watcher.
294 443
295 my $udp_socket = ... 444 my $udp_socket = ...
296 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 445 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
297 $1000udp_watcher->keepalive (0); 446 $udp_watcher->keepalive (0);
298 447
299 $loop = $w->loop 448 $loop = $w->loop
300 Return the loop that this watcher is attached to. 449 Return the loop that this watcher is attached to.
301 450
302WATCHER TYPES 451WATCHER TYPES
… …
390 changed by explicit date -s or other means such as ntpd). It is also 539 changed by explicit date -s or other means such as ntpd). It is also
391 the most complex watcher type in EV. 540 the most complex watcher type in EV.
392 541
393 It has three distinct "modes": 542 It has three distinct "modes":
394 543
395 * absolute timer ($interval = $reschedule_cb = 0) 544 * absolute timer ($interval = $reschedule_cb = 0)
545
396 This time simply fires at the wallclock time $at and doesn't 546 This time simply fires at the wallclock time $at and doesn't
397 repeat. It will not adjust when a time jump occurs, that is, if 547 repeat. It will not adjust when a time jump occurs, that is, if
398 it is to be run at January 1st 2011 then it will run when the 548 it is to be run at January 1st 2011 then it will run when the
399 system time reaches or surpasses this time. 549 system time reaches or surpasses this time.
400 550
401 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 551 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
552
402 In this mode the watcher will always be scheduled to time out at 553 In this mode the watcher will always be scheduled to time out at
403 the next "$at + N * $interval" time (for some integer N) and 554 the next "$at + N * $interval" time (for some integer N) and
404 then repeat, regardless of any time jumps. 555 then repeat, regardless of any time jumps.
405 556
406 This can be used to create timers that do not drift with respect 557 This can be used to create timers that do not drift with respect
407 to system time: 558 to system time:
408 559
409 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; 560 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
410 561
411 That doesn't mean there will always be 3600 seconds in between 562 That doesn't mean there will always be 3600 seconds in between
412 triggers, but only that the the clalback will be called when the 563 triggers, but only that the the callback will be called when the
413 system time shows a full hour (UTC). 564 system time shows a full hour (UTC).
414 565
415 Another way to think about it (for the mathematically inclined) 566 Another way to think about it (for the mathematically inclined)
416 is that EV::periodic will try to run the callback in this mode 567 is that EV::periodic will try to run the callback in this mode
417 at the next possible time where "$time = $at (mod $interval)", 568 at the next possible time where "$time = $at (mod $interval)",
418 regardless of any time jumps. 569 regardless of any time jumps.
419 570
420 * manual reschedule mode ($reschedule_cb = coderef) 571 * manual reschedule mode ($reschedule_cb = coderef)
572
421 In this mode $interval and $at are both being ignored. Instead, 573 In this mode $interval and $at are both being ignored. Instead,
422 each time the periodic watcher gets scheduled, the reschedule 574 each time the periodic watcher gets scheduled, the reschedule
423 callback ($reschedule_cb) will be called with the watcher as 575 callback ($reschedule_cb) will be called with the watcher as
424 first, and the current time as second argument. 576 first, and the current time as second argument.
425 577
426 *This callback MUST NOT stop or destroy this or any other 578 *This callback MUST NOT stop or destroy this or any other
579 periodic watcher, ever, and MUST NOT call any event loop
427 periodic watcher, ever*. If you need to stop it, return 1e30 and 580 functions or methods*. If you need to stop it, return 1e30 and
428 stop it afterwards. 581 stop it afterwards. You may create and start a "EV::prepare"
582 watcher for this task.
429 583
430 It must return the next time to trigger, based on the passed 584 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 585 time value (that is, the lowest time value larger than or equal
432 second argument). It will usually be called just before the 586 to to the second argument). It will usually be called just
433 callback will be triggered, but might be called at other times, 587 before the callback will be triggered, but might be called at
434 too. 588 other times, too.
435 589
436 This can be used to create very complex timers, such as a timer 590 This can be used to create very complex timers, such as a timer
437 that triggers on each midnight, local time (actually 24 hours 591 that triggers on each midnight, local time (actually 24 hours
438 after the last midnight, to keep the example simple. If you know 592 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 593 a way to do it correctly in about the same space (without
… …
463 Return the time that the watcher is expected to trigger next. 617 Return the time that the watcher is expected to trigger next.
464 618
465 SIGNAL WATCHERS - signal me when a signal gets signalled! 619 SIGNAL WATCHERS - signal me when a signal gets signalled!
466 $w = EV::signal $signal, $callback 620 $w = EV::signal $signal, $callback
467 $w = EV::signal_ns $signal, $callback 621 $w = EV::signal_ns $signal, $callback
622 $w = $loop->signal ($signal, $callback)
623 $w = $loop->signal_ns ($signal, $callback)
468 Call the callback when $signal is received (the signal can be 624 Call the callback when $signal is received (the signal can be
469 specified by number or by name, just as with "kill" or %SIG). 625 specified by number or by name, just as with "kill" or %SIG).
626
627 Only one event loop can grab a given signal - attempting to grab the
628 same signal from two EV loops will crash the program immediately or
629 cause data corruption.
470 630
471 EV will grab the signal for the process (the kernel only allows one 631 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 632 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 633 watcher, and removes it again when you stop it. Perl does the same
474 when you add/remove callbacks to %SIG, so watch out. 634 when you add/remove callbacks to %SIG, so watch out.
… …
486 $old_signum = $w->signal ($new_signal) 646 $old_signum = $w->signal ($new_signal)
487 Returns the previously set signal (always as a number not name) and 647 Returns the previously set signal (always as a number not name) and
488 optionally set a new one. 648 optionally set a new one.
489 649
490 CHILD WATCHERS - watch out for process status changes 650 CHILD WATCHERS - watch out for process status changes
491 $w = EV::child $pid, $callback 651 $w = EV::child $pid, $trace, $callback
492 $w = EV::child_ns $pid, $callback 652 $w = EV::child_ns $pid, $trace, $callback
493 $w = $loop->child ($pid, $callback) 653 $w = $loop->child ($pid, $trace, $callback)
494 $w = $loop->child_ns ($pid, $callback) 654 $w = $loop->child_ns ($pid, $trace, $callback)
495 Call the callback when a status change for pid $pid (or any pid if 655 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 656 $pid is 0) has been received (a status change happens when the
657 process terminates or is killed, or, when trace is true,
658 additionally when it is stopped or continued). More precisely: when
497 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 659 the process receives a "SIGCHLD", EV will fetch the outstanding
498 for all changed/zombie children and call the callback. 660 exit/wait status for all changed/zombie children and call the
661 callback.
499 662
500 It is valid (and fully supported) to install a child watcher after a 663 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 664 child has exited but before the event loop has started its next
502 iteration (for example, first you "fork", then the new child process 665 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 666 might exit, and only then do you install a child watcher in the
… …
510 be called. 673 be called.
511 674
512 The "child_ns" variant doesn't start (activate) the newly created 675 The "child_ns" variant doesn't start (activate) the newly created
513 watcher. 676 watcher.
514 677
515 $w->set ($pid) 678 $w->set ($pid, $trace)
516 Reconfigures the watcher, see the constructor above for details. Can 679 Reconfigures the watcher, see the constructor above for details. Can
517 be called at any time. 680 be called at any time.
518 681
519 $current_pid = $w->pid 682 $current_pid = $w->pid
520 $old_pid = $w->pid ($new_pid)
521 Returns the previously set process id and optionally set a new one. 683 Returns the previously set process id and optionally set a new one.
522 684
523 $exit_status = $w->rstatus 685 $exit_status = $w->rstatus
524 Return the exit/wait status (as returned by waitpid, see the waitpid 686 Return the exit/wait status (as returned by waitpid, see the waitpid
525 entry in perlfunc). 687 entry in perlfunc).
… …
646 $w = $loop->check_ns ($callback) 808 $w = $loop->check_ns ($callback)
647 Call the callback just after the process wakes up again (after it 809 Call the callback just after the process wakes up again (after it
648 has gathered events), but before any other callbacks have been 810 has gathered events), but before any other callbacks have been
649 invoked. 811 invoked.
650 812
651 This is used to integrate other event-based software into the EV 813 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 814 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 815 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 816 real-world example of integrating Net::SNMP (with some details left
655 out): 817 out):
656 818
… …
687 # make the dispatcher handle any new stuff 849 # make the dispatcher handle any new stuff
688 ... not shown 850 ... not shown
689 }; 851 };
690 852
691 The callbacks of the created watchers will not be called as the 853 The callbacks of the created watchers will not be called as the
692 watchers are destroyed before this cna happen (remember EV::check 854 watchers are destroyed before this can happen (remember EV::check
693 gets called first). 855 gets called first).
694 856
695 The "check_ns" variant doesn't start (activate) the newly created 857 The "check_ns" variant doesn't start (activate) the newly created
696 watcher. 858 watcher.
859
860 EV::CHECK constant issues
861 Like all other watcher types, there is a bitmask constant for use in
862 $revents and other places. The "EV::CHECK" is special as it has the
863 same name as the "CHECK" sub called by Perl. This doesn't cause big
864 issues on newer perls (beginning with 5.8.9), but it means thatthe
865 constant must be *inlined*, i.e. runtime calls will not work. That
866 means that as long as you always "use EV" and then "EV::CHECK" you
867 are on the safe side.
697 868
698 FORK WATCHERS - the audacity to resume the event loop after a fork 869 FORK WATCHERS - the audacity to resume the event loop after a fork
699 Fork watchers are called when a "fork ()" was detected. The invocation 870 Fork watchers are called when a "fork ()" was detected. The invocation
700 is done before the event loop blocks next and before "check" watchers 871 is done before the event loop blocks next and before "check" watchers
701 are being called, and only in the child after the fork. 872 are being called, and only in the child after the fork.
… …
708 process after a fork. 879 process after a fork.
709 880
710 The "fork_ns" variant doesn't start (activate) the newly created 881 The "fork_ns" variant doesn't start (activate) the newly created
711 watcher. 882 watcher.
712 883
884 EMBED WATCHERS - when one backend isn't enough...
885 This is a rather advanced watcher type that lets you embed one event
886 loop into another (currently only IO events are supported in the
887 embedded loop, other types of watchers might be handled in a delayed or
888 incorrect fashion and must not be used).
889
890 See the libev documentation at
891 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
892 _when_one_backend_> (locally installed as EV::libev) for more details.
893
894 In short, this watcher is most useful on BSD systems without working
895 kqueue to still be able to handle a large number of sockets:
896
897 my $socket_loop;
898
899 # check wether we use SELECT or POLL _and_ KQUEUE is supported
900 if (
901 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
902 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
903 ) {
904 # use kqueue for sockets
905 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
906 }
907
908 # use the default loop otherwise
909 $socket_loop ||= EV::default_loop;
910
911 $w = EV::embed $otherloop[, $callback]
912 $w = EV::embed_ns $otherloop[, $callback]
913 $w = $loop->embed ($otherloop[, $callback])
914 $w = $loop->embed_ns ($otherloop[, $callback])
915 Call the callback when the embedded event loop ($otherloop) has any
916 I/O activity. The $callback is optional: if it is missing, then the
917 embedded event loop will be managed automatically (which is
918 recommended), otherwise you have to invoke "sweep" yourself.
919
920 The "embed_ns" variant doesn't start (activate) the newly created
921 watcher.
922
923 ASYNC WATCHERS - how to wake up another event loop
924 Async watchers are provided by EV, but have little use in perl directly,
925 as perl neither supports threads running in parallel nor direct access
926 to signal handlers or other contexts where they could be of value.
927
928 It is, however, possible to use them from the XS level.
929
930 Please see the libev documentation for further details.
931
932 $w = EV::async $callback
933 $w = EV::async_ns $callback
934 $w = $loop->async ($callback)
935 $w = $loop->async_ns ($callback)
936 $w->send
937 $bool = $w->async_pending
938
939 CLEANUP WATCHERS - how to clean up when the event loop goes away
940 Cleanup watchers are not supported on the Perl level, they can only be
941 used via XS currently.
942
713PERL SIGNALS 943PERL SIGNALS
714 While Perl signal handling (%SIG) is not affected by EV, the behaviour 944 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 945 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 946 handled when Perl runs, which means your signal handler might be invoked
717 only the next time an event callback is invoked. 947 only the next time an event callback is invoked.
… …
726 my $async_check = EV::check sub { }; 956 my $async_check = EV::check sub { };
727 957
728 This ensures that perl gets into control for a short time to handle any 958 This ensures that perl gets into control for a short time to handle any
729 pending signals, and also ensures (slightly) slower overall operation. 959 pending signals, and also ensures (slightly) slower overall operation.
730 960
731THREADS 961ITHREADS
732 Threads are not supported by this module in any way. Perl pseudo-threads 962 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 963 pseudo-threads is evil stuff and must die. Real threads as provided by
734 work on thread support for it. 964 Coro are fully supported (and enhanced support is available via
965 Coro::EV).
735 966
736FORK 967FORK
737 Most of the "improved" event delivering mechanisms of modern operating 968 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 969 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 970 not supported and usually destructive). Libev makes it possible to work
… …
749 980
750 On win32, there is no notion of fork so all this doesn't apply, of 981 On win32, there is no notion of fork so all this doesn't apply, of
751 course. 982 course.
752 983
753SEE ALSO 984SEE ALSO
754 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event 985 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
755 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines 986 DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed
756 with EV), Net::SNMP::EV (asynchronous SNMP). 987 Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV
988 (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event
989 driven programming.
757 990
758AUTHOR 991AUTHOR
759 Marc Lehmann <schmorp@schmorp.de> 992 Marc Lehmann <schmorp@schmorp.de>
760 http://home.schmorp.de/ 993 http://home.schmorp.de/
761 994

Diff Legend

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