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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 7
8 # TIMERS 8 # TIMERS
9 9
10 my $w = EV::timer 2, 0, sub { 10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s"; 11 warn "is called after 2s";
12 }; 12 };
13 13
14 my $w = EV::timer 2, 2, sub { 14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)"; 15 warn "is called roughly every 2s (repeat = 2)";
16 }; 16 };
17 17
18 undef $w; # destroy event watcher again 18 undef $w; # destroy event watcher again
19 19
20 my $w = EV::periodic 0, 60, 0, sub { 20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly"; 21 warn "is called every minute, on the minute, exactly";
22 }; 22 };
23 23
24 # IO 24 # IO
25 25
26 my $w = EV::io *STDIN, EV::READ, sub { 26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask 27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>; 28 warn "stdin is readable, you entered: ", <STDIN>;
29 }; 29 };
30 30
31 # SIGNALS 31 # SIGNALS
32 32
33 my $w = EV::signal 'QUIT', sub { 33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n"; 34 warn "sigquit received\n";
35 }; 35 };
36 36
37 # CHILD/PID STATUS CHANGES 37 # CHILD/PID STATUS CHANGES
38 38
39 my $w = EV::child 666, 0, sub { 39 my $w = EV::child 666, 0, sub {
40 my ($w, $revents) = @_; 40 my ($w, $revents) = @_;
41 my $status = $w->rstatus; 41 my $status = $w->rstatus;
42 }; 42 };
43 43
44 # STAT CHANGES 44 # STAT CHANGES
45 my $w = EV::stat "/etc/passwd", 10, sub { 45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_; 46 my ($w, $revents) = @_;
47 warn $w->path, " has changed somehow.\n"; 47 warn $w->path, " has changed somehow.\n";
48 }; 48 };
49 49
50 # MAINLOOP 50 # MAINLOOP
51 EV::loop; # loop until EV::unloop is called or all watchers stop 51 EV::run; # loop until EV::break 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://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) 68 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
60 for more subtle details on watcher semantics or some discussion on the 69 perldoc EV::libev) for more subtle details on watcher semantics or some
61 available backends, or how to force a specific backend with 70 discussion on the available backends, or how to force a specific backend
62 "LIBEV_FLAGS", or just about in any case because it has much more 71 with "LIBEV_FLAGS", or just about in any case because it has much more
63 detailed information. 72 detailed information.
64 73
65 This module is very fast and scalable. It is actually so fast that you 74 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 75 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) 76 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 77 and still be faster than with any other event loop currently supported
69 in Perl. 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.
70 112
71EVENT LOOPS 113EVENT LOOPS
72 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"
73 that can handle everything including signals and child watchers, and any 115 that can handle everything including signals and child watchers, and any
74 number of "dynamic event loops" that can use different backends (with 116 number of "dynamic event loops" that can use different backends (with
… …
81 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
82 modules (e.g. AnyEvent or Coro) and most portable event loop. 124 modules (e.g. AnyEvent or Coro) and most portable event loop.
83 125
84 For specific programs you can create additional event loops dynamically. 126 For specific programs you can create additional event loops dynamically.
85 127
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
86 $loop = new EV::loop [$flags] 135 $loop = new EV::Loop [$flags]
87 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
88 the "ev_loop_new ()" function description in the libev documentation 137 the "ev_loop_new ()" function description in the libev documentation
89 (<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
90 ONS>) for more info. 139 ONS>, or locally-installed as EV::libev manpage) for more info.
91 140
92 The loop will automatically be destroyed when it is no longer 141 The loop will automatically be destroyed when it is no longer
93 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.
94 143
95 Using "EV::FLAG_FORKCHECK" is recommended, as only the default event 144 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
96 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.
97 149
98 $loop->loop_fork 150 $loop->loop_fork
99 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
100 continuing the event loop. An alternative is to use 152 continuing the event loop. An alternative is to use
101 "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at 153 "EV::FLAG_FORKCHECK" which calls this function automatically, at
102 some performance loss (refer to the libev documentation). 154 some performance loss (refer to the libev documentation).
103 155
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
104 $loop = EV::default_loop [$flags] 161 $loop = EV::default_loop [$flags]
105 Return the default loop (which is a singleton object). 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.
106 167
107BASIC INTERFACE 168BASIC INTERFACE
108 $EV::DIED 169 $EV::DIED
109 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
110 callback throws an exception (with $@ containing the error). The 171 callback throws an exception (with $@ containing the error). The
… …
127 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
128 189
129 $time = EV::now 190 $time = EV::now
130 $time = $loop->now 191 $time = $loop->now
131 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
132 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
133 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").
134 232
135 $backend = EV::backend 233 $backend = EV::backend
136 $backend = $loop->backend 234 $backend = $loop->backend
137 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
138 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
139 237
140 EV::loop [$flags] 238 $active = EV::run [$flags]
141 $loop->loop ([$flags]) 239 $active = $loop->run ([$flags])
142 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
143 callback calls EV::unloop. 241 callback calls EV::break or the flasg are nonzero (in which case the
242 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".
144 246
145 The $flags argument can be one of the following: 247 The $flags argument can be one of the following:
146 248
147 0 as above 249 0 as above
148 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 250 EV::RUN_ONCE block at most once (wait, but do not loop)
149 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 251 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
150 252
151 EV::unloop [$how] 253 EV::break [$how]
152 $loop->unloop ([$how]) 254 $loop->break ([$how])
153 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
154 makes the innermost call to EV::loop return. 256 the innermost call to EV::loop return.
155 257
156 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
157 EV::loop will return as fast as possible. 259 will return as fast as possible.
158 260
159 $count = EV::loop_count 261 When called with an argument of EV::BREAK_CANCEL, any pending break
160 $count = $loop->loop_count 262 will be cancelled.
263
264 $count = EV::iteration
265 $count = $loop->iteration
161 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.
162 Sometiems useful as a generation counter. 267 Sometimes useful as a generation counter.
163 268
164 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 269 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
165 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) 270 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
166 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
167 one-shot event without the need for managing a watcher object. 272 one-shot event without the need for managing a watcher object.
… …
176 Otherwise a EV::timer with this value will be started. 281 Otherwise a EV::timer with this value will be started.
177 282
178 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,
179 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
180 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",
181 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 286 "EV::READ", "EV::WRITE" and "EV::TIMER").
182 287
183 EV::once doesn't return anything: the watchers stay active till 288 EV::once doesn't return anything: the watchers stay active till
184 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
185 the callback invoked. 290 the callback invoked.
186 291
187 EV::feed_fd_event ($fd, $revents) 292 EV::feed_fd_event $fd, $revents
188 $loop->feed_fd_event ($fd, $revents) 293 $loop->feed_fd_event ($fd, $revents)
189 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
190 call as if the readyness notifications specified by $revents (a 295 call as if the readyness notifications specified by $revents (a
191 combination of "EV::READ" and "EV::WRITE") happened on the file 296 combination of "EV::READ" and "EV::WRITE") happened on the file
192 descriptor $fd. 297 descriptor $fd.
193 298
194 EV::feed_signal_event ($signal) 299 EV::feed_signal_event $signal
195 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
196 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.
197 307
198 EV::set_io_collect_interval $time 308 EV::set_io_collect_interval $time
199 $loop->set_io_collect_interval ($time) 309 $loop->set_io_collect_interval ($time)
200 EV::set_timeout_collect_interval $time 310 EV::set_timeout_collect_interval $time
201 $loop->set_timeout_collect_interval ($time) 311 $loop->set_timeout_collect_interval ($time)
202 These advanced functions set the minimum block interval when polling 312 These advanced functions set the minimum block interval when polling
203 for I/O events and the minimum wait interval for timer events. See 313 for I/O events and the minimum wait interval for timer events. See
204 the libev documentation at 314 the libev documentation at
205 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT 315 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
206 ROLLING_THE_EVENT_LOOP> for a more detailed discussion. 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.
207 326
208WATCHER OBJECTS 327WATCHER OBJECTS
209 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
210 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,
211 you would create an EV::io watcher for that: 330 you would create an EV::io watcher for that:
212 331
213 my $watcher = EV::io *STDIN, EV::READ, sub { 332 my $watcher = EV::io *STDIN, EV::READ, sub {
214 my ($watcher, $revents) = @_; 333 my ($watcher, $revents) = @_;
215 warn "yeah, STDIN should now be readable without blocking!\n" 334 warn "yeah, STDIN should now be readable without blocking!\n"
216 }; 335 };
217 336
218 All watchers can be active (waiting for events) or inactive (paused). 337 All watchers can be active (waiting for events) or inactive (paused).
219 Only active watchers will have their callbacks invoked. All callbacks 338 Only active watchers will have their callbacks invoked. All callbacks
220 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
221 received events. 340 received events.
222 341
223 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
224 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
225 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,
226 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
227 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).
228 (which uses EV::TIMEOUT).
229 347
230 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
231 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
232 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.
233 351
… …
298 the watcher isn't pending it does nothing and returns 0. 416 the watcher isn't pending it does nothing and returns 0.
299 417
300 $previous_state = $w->keepalive ($bool) 418 $previous_state = $w->keepalive ($bool)
301 Normally, "EV::loop" will return when there are no active watchers 419 Normally, "EV::loop" will return when there are no active watchers
302 (which is a "deadlock" because no progress can be made anymore). 420 (which is a "deadlock" because no progress can be made anymore).
303 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
304 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
305 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
306 for their task :). 424 for their task :).
307 425
308 Sometimes, however, this gets in your way, for example when the 426 Sometimes, however, this gets in your way, for example when the
… …
315 433
316 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
317 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
318 returning. 436 returning.
319 437
320 The initial value for keepalive is true (enabled), and you cna 438 The initial value for keepalive is true (enabled), and you can
321 change it any time. 439 change it any time.
322 440
323 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
324 the event loop from running just because of that watcher. 442 the event loop from running just because of that watcher.
325 443
326 my $udp_socket = ... 444 my $udp_socket = ...
327 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 445 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
328 $1000udp_watcher->keepalive (0); 446 $udp_watcher->keepalive (0);
329 447
330 $loop = $w->loop 448 $loop = $w->loop
331 Return the loop that this watcher is attached to. 449 Return the loop that this watcher is attached to.
332 450
333WATCHER TYPES 451WATCHER TYPES
… …
383 the same time. 501 the same time.
384 502
385 The "timer_ns" variant doesn't start (activate) the newly created 503 The "timer_ns" variant doesn't start (activate) the newly created
386 watcher. 504 watcher.
387 505
388 $w->set ($after, $repeat) 506 $w->set ($after, $repeat = 0)
389 Reconfigures the watcher, see the constructor above for details. Can 507 Reconfigures the watcher, see the constructor above for details. Can
390 be called at any time. 508 be called at any time.
391 509
392 $w->again 510 $w->again
511 $w->again ($repeat)
393 Similar to the "start" method, but has special semantics for 512 Similar to the "start" method, but has special semantics for
394 repeating timers: 513 repeating timers:
395 514
396 If the timer is active and non-repeating, it will be stopped. 515 If the timer is active and non-repeating, it will be stopped.
397 516
… …
405 524
406 This behaviour is useful when you have a timeout for some IO 525 This behaviour is useful when you have a timeout for some IO
407 operation. You create a timer object with the same value for $after 526 operation. You create a timer object with the same value for $after
408 and $repeat, and then, in the read/write watcher, run the "again" 527 and $repeat, and then, in the read/write watcher, run the "again"
409 method on the timeout. 528 method on the timeout.
529
530 If called with a $repeat argument, then it uses this a timer repeat
531 value.
532
533 $after = $w->remaining
534 Calculates and returns the remaining time till the timer will fire.
410 535
411 PERIODIC WATCHERS - to cron or not to cron? 536 PERIODIC WATCHERS - to cron or not to cron?
412 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 537 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
413 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 538 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
414 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback) 539 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
… …
440 to system time: 565 to system time:
441 566
442 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; 567 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
443 568
444 That doesn't mean there will always be 3600 seconds in between 569 That doesn't mean there will always be 3600 seconds in between
445 triggers, but only that the the clalback will be called when the 570 triggers, but only that the the callback will be called when the
446 system time shows a full hour (UTC). 571 system time shows a full hour (UTC).
447 572
448 Another way to think about it (for the mathematically inclined) 573 Another way to think about it (for the mathematically inclined)
449 is that EV::periodic will try to run the callback in this mode 574 is that EV::periodic will try to run the callback in this mode
450 at the next possible time where "$time = $at (mod $interval)", 575 at the next possible time where "$time = $at (mod $interval)",
… …
456 each time the periodic watcher gets scheduled, the reschedule 581 each time the periodic watcher gets scheduled, the reschedule
457 callback ($reschedule_cb) will be called with the watcher as 582 callback ($reschedule_cb) will be called with the watcher as
458 first, and the current time as second argument. 583 first, and the current time as second argument.
459 584
460 *This callback MUST NOT stop or destroy this or any other 585 *This callback MUST NOT stop or destroy this or any other
586 periodic watcher, ever, and MUST NOT call any event loop
461 periodic watcher, ever*. If you need to stop it, return 1e30 and 587 functions or methods*. If you need to stop it, return 1e30 and
462 stop it afterwards. 588 stop it afterwards. You may create and start a "EV::prepare"
589 watcher for this task.
463 590
464 It must return the next time to trigger, based on the passed 591 It must return the next time to trigger, based on the passed
465 time value (that is, the lowest time value larger than to the 592 time value (that is, the lowest time value larger than or equal
466 second argument). It will usually be called just before the 593 to to the second argument). It will usually be called just
467 callback will be triggered, but might be called at other times, 594 before the callback will be triggered, but might be called at
468 too. 595 other times, too.
469 596
470 This can be used to create very complex timers, such as a timer 597 This can be used to create very complex timers, such as a timer
471 that triggers on each midnight, local time (actually 24 hours 598 that triggers on each midnight, local time (actually 24 hours
472 after the last midnight, to keep the example simple. If you know 599 after the last midnight, to keep the example simple. If you know
473 a way to do it correctly in about the same space (without 600 a way to do it correctly in about the same space (without
… …
497 Return the time that the watcher is expected to trigger next. 624 Return the time that the watcher is expected to trigger next.
498 625
499 SIGNAL WATCHERS - signal me when a signal gets signalled! 626 SIGNAL WATCHERS - signal me when a signal gets signalled!
500 $w = EV::signal $signal, $callback 627 $w = EV::signal $signal, $callback
501 $w = EV::signal_ns $signal, $callback 628 $w = EV::signal_ns $signal, $callback
629 $w = $loop->signal ($signal, $callback)
630 $w = $loop->signal_ns ($signal, $callback)
502 Call the callback when $signal is received (the signal can be 631 Call the callback when $signal is received (the signal can be
503 specified by number or by name, just as with "kill" or %SIG). 632 specified by number or by name, just as with "kill" or %SIG).
633
634 Only one event loop can grab a given signal - attempting to grab the
635 same signal from two EV loops will crash the program immediately or
636 cause data corruption.
504 637
505 EV will grab the signal for the process (the kernel only allows one 638 EV will grab the signal for the process (the kernel only allows one
506 component to receive a signal at a time) when you start a signal 639 component to receive a signal at a time) when you start a signal
507 watcher, and removes it again when you stop it. Perl does the same 640 watcher, and removes it again when you stop it. Perl does the same
508 when you add/remove callbacks to %SIG, so watch out. 641 when you add/remove callbacks to %SIG, so watch out.
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682 $w = $loop->check_ns ($callback) 815 $w = $loop->check_ns ($callback)
683 Call the callback just after the process wakes up again (after it 816 Call the callback just after the process wakes up again (after it
684 has gathered events), but before any other callbacks have been 817 has gathered events), but before any other callbacks have been
685 invoked. 818 invoked.
686 819
687 This is used to integrate other event-based software into the EV 820 This can be used to integrate other event-based software into the EV
688 mainloop: You register a prepare callback and in there, you create 821 mainloop: You register a prepare callback and in there, you create
689 io and timer watchers as required by the other software. Here is a 822 io and timer watchers as required by the other software. Here is a
690 real-world example of integrating Net::SNMP (with some details left 823 real-world example of integrating Net::SNMP (with some details left
691 out): 824 out):
692 825
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723 # make the dispatcher handle any new stuff 856 # make the dispatcher handle any new stuff
724 ... not shown 857 ... not shown
725 }; 858 };
726 859
727 The callbacks of the created watchers will not be called as the 860 The callbacks of the created watchers will not be called as the
728 watchers are destroyed before this cna happen (remember EV::check 861 watchers are destroyed before this can happen (remember EV::check
729 gets called first). 862 gets called first).
730 863
731 The "check_ns" variant doesn't start (activate) the newly created 864 The "check_ns" variant doesn't start (activate) the newly created
732 watcher. 865 watcher.
866
867 EV::CHECK constant issues
868 Like all other watcher types, there is a bitmask constant for use in
869 $revents and other places. The "EV::CHECK" is special as it has the
870 same name as the "CHECK" sub called by Perl. This doesn't cause big
871 issues on newer perls (beginning with 5.8.9), but it means thatthe
872 constant must be *inlined*, i.e. runtime calls will not work. That
873 means that as long as you always "use EV" and then "EV::CHECK" you
874 are on the safe side.
733 875
734 FORK WATCHERS - the audacity to resume the event loop after a fork 876 FORK WATCHERS - the audacity to resume the event loop after a fork
735 Fork watchers are called when a "fork ()" was detected. The invocation 877 Fork watchers are called when a "fork ()" was detected. The invocation
736 is done before the event loop blocks next and before "check" watchers 878 is done before the event loop blocks next and before "check" watchers
737 are being called, and only in the child after the fork. 879 are being called, and only in the child after the fork.
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752 embedded loop, other types of watchers might be handled in a delayed or 894 embedded loop, other types of watchers might be handled in a delayed or
753 incorrect fashion and must not be used). 895 incorrect fashion and must not be used).
754 896
755 See the libev documentation at 897 See the libev documentation at
756 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code 898 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
757 _when_one_backend_> for more details. 899 _when_one_backend_> (locally installed as EV::libev) for more details.
758 900
759 In short, this watcher is most useful on BSD systems without working 901 In short, this watcher is most useful on BSD systems without working
760 kqueue to still be able to handle a large number of sockets: 902 kqueue to still be able to handle a large number of sockets:
761 903
762 my $socket_loop; 904 my $socket_loop;
763 905
764 # check wether we use SELECT or POLL _and_ KQUEUE is supported 906 # check wether we use SELECT or POLL _and_ KQUEUE is supported
765 if ( 907 if (
766 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT)) 908 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
767 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE) 909 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
768 ) { 910 ) {
769 # use kqueue for sockets 911 # use kqueue for sockets
770 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV; 912 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
771 } 913 }
772 914
773 # use the default loop otherwise 915 # use the default loop otherwise
774 $socket_loop ||= EV::default_loop; 916 $socket_loop ||= EV::default_loop;
775 917
776 $w = EV::embed $otherloop, $callback 918 $w = EV::embed $otherloop[, $callback]
777 $w = EV::embed_ns $otherloop, $callback 919 $w = EV::embed_ns $otherloop[, $callback]
778 $w = $loop->embed ($otherloop, $callback) 920 $w = $loop->embed ($otherloop[, $callback])
779 $w = $loop->embed_ns ($otherloop, $callback) 921 $w = $loop->embed_ns ($otherloop[, $callback])
780 Call the callback when the embedded event loop ($otherloop) has any 922 Call the callback when the embedded event loop ($otherloop) has any
781 I/O activity. The $callback should alwas be specified as "undef" in 923 I/O activity. The $callback is optional: if it is missing, then the
782 this version of EV, which means the embedded event loop will be 924 embedded event loop will be managed automatically (which is
783 managed automatically. 925 recommended), otherwise you have to invoke "sweep" yourself.
784 926
785 The "embed_ns" variant doesn't start (activate) the newly created 927 The "embed_ns" variant doesn't start (activate) the newly created
786 watcher. 928 watcher.
787 929
788 ASYNC WATCHERS - how to wake up another event loop 930 ASYNC WATCHERS - how to wake up another event loop
789 Async watchers are provided by EV, but have little use in perl directly, 931 Async watchers are provided by EV, but have little use in perl directly,
790 as perl neither supports threads nor direct access to signal handlers or 932 as perl neither supports threads running in parallel nor direct access
791 other contexts where they could be of value. 933 to signal handlers or other contexts where they could be of value.
792 934
793 It is, however, possible to use them from the XS level. 935 It is, however, possible to use them from the XS level.
794 936
795 Please see the libev documentation for further details. 937 Please see the libev documentation for further details.
796 938
797 $w = EV::async $callback 939 $w = EV::async $callback
798 $w = EV::async_ns $callback 940 $w = EV::async_ns $callback
941 $w = $loop->async ($callback)
942 $w = $loop->async_ns ($callback)
799 $w->send 943 $w->send
800 $bool = $w->async_pending 944 $bool = $w->async_pending
945
946 CLEANUP WATCHERS - how to clean up when the event loop goes away
947 Cleanup watchers are not supported on the Perl level, they can only be
948 used via XS currently.
801 949
802PERL SIGNALS 950PERL SIGNALS
803 While Perl signal handling (%SIG) is not affected by EV, the behaviour 951 While Perl signal handling (%SIG) is not affected by EV, the behaviour
804 with EV is as the same as any other C library: Perl-signals will only be 952 with EV is as the same as any other C library: Perl-signals will only be
805 handled when Perl runs, which means your signal handler might be invoked 953 handled when Perl runs, which means your signal handler might be invoked
… …
815 my $async_check = EV::check sub { }; 963 my $async_check = EV::check sub { };
816 964
817 This ensures that perl gets into control for a short time to handle any 965 This ensures that perl gets into control for a short time to handle any
818 pending signals, and also ensures (slightly) slower overall operation. 966 pending signals, and also ensures (slightly) slower overall operation.
819 967
820THREADS 968ITHREADS
821 Threads are not supported by this module in any way. Perl pseudo-threads 969 Ithreads are not supported by this module in any way. Perl
822 is evil stuff and must die. As soon as Perl gains real threads I will 970 pseudo-threads is evil stuff and must die. Real threads as provided by
823 work on thread support for it. 971 Coro are fully supported (and enhanced support is available via
972 Coro::EV).
824 973
825FORK 974FORK
826 Most of the "improved" event delivering mechanisms of modern operating 975 Most of the "improved" event delivering mechanisms of modern operating
827 systems have quite a few problems with fork(2) (to put it bluntly: it is 976 systems have quite a few problems with fork(2) (to put it bluntly: it is
828 not supported and usually destructive). Libev makes it possible to work 977 not supported and usually destructive). Libev makes it possible to work
… …
838 987
839 On win32, there is no notion of fork so all this doesn't apply, of 988 On win32, there is no notion of fork so all this doesn't apply, of
840 course. 989 course.
841 990
842SEE ALSO 991SEE ALSO
843 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event 992 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
844 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines 993 DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed
845 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop 994 Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV
846 agnostic and portable event driven programming. 995 (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event
996 driven programming.
847 997
848AUTHOR 998AUTHOR
849 Marc Lehmann <schmorp@schmorp.de> 999 Marc Lehmann <schmorp@schmorp.de>
850 http://home.schmorp.de/ 1000 http://home.schmorp.de/
851 1001

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