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Revision 1.30 by root, Thu Oct 23 04:56:49 2008 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 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, 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::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". 61 discussion on the available backends, or how to force a specific backend
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 avdantage 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.
62 128
63BASIC INTERFACE 129BASIC INTERFACE
64 $EV::DIED 130 $EV::DIED
65 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
66 callback throws an exception (with $@ containing thr error). The 132 callback throws an exception (with $@ containing the error). The
67 default prints an informative message and continues. 133 default prints an informative message and continues.
68 134
69 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.
70 147
71 $time = EV::time 148 $time = EV::time
72 Returns the current time in (fractional) seconds since the epoch. 149 Returns the current time in (fractional) seconds since the epoch.
73 150
74 $time = EV::now 151 $time = EV::now
152 $time = $loop->now
75 Returns the time the last event loop iteration has been started. 153 Returns the time the last event loop iteration has been started.
76 This is the time that (relative) timers are based on, and refering 154 This is the time that (relative) timers are based on, and refering
77 to it is usually faster then calling EV::time. 155 to it is usually faster then calling EV::time.
78 156
79 $method = EV::method 157 $backend = EV::backend
158 $backend = $loop->backend
80 Returns an integer describing the backend used by libev 159 Returns an integer describing the backend used by libev
81 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 160 (EV::METHOD_SELECT or EV::METHOD_EPOLL).
82 161
83 EV::loop [$flags] 162 EV::loop [$flags]
163 $loop->loop ([$flags])
84 Begin checking for events and calling callbacks. It returns when a 164 Begin checking for events and calling callbacks. It returns when a
85 callback calls EV::unloop. 165 callback calls EV::unloop.
86 166
87 The $flags argument can be one of the following: 167 The $flags argument can be one of the following:
88 168
89 0 as above 169 0 as above
90 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 170 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
91 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 171 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
92 172
93 EV::unloop [$how] 173 EV::unloop [$how]
174 $loop->unloop ([$how])
94 When called with no arguments or an argument of EV::UNLOOP_ONE, 175 When called with no arguments or an argument of EV::UNLOOP_ONE,
95 makes the innermost call to EV::loop return. 176 makes the innermost call to EV::loop return.
96 177
97 When called with an argument of EV::UNLOOP_ALL, all calls to 178 When called with an argument of EV::UNLOOP_ALL, all calls to
98 EV::loop will return as fast as possible. 179 EV::loop will return as fast as possible.
99 180
181 $count = EV::loop_count
182 $count = $loop->loop_count
183 Return the number of times the event loop has polled for new events.
184 Sometiems useful as a generation counter.
185
100 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 186 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
187 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
101 This function rolls together an I/O and a timer watcher for a single 188 This function rolls together an I/O and a timer watcher for a single
102 one-shot event without the need for managing a watcher object. 189 one-shot event without the need for managing a watcher object.
103 190
104 If $fh_or_undef is a filehandle or file descriptor, then $events 191 If $fh_or_undef is a filehandle or file descriptor, then $events
105 must be a bitset containing either "EV::READ", "EV::WRITE" or 192 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
110 If timeout is "undef" or negative, then there will be no timeout. 197 If timeout is "undef" or negative, then there will be no timeout.
111 Otherwise a EV::timer with this value will be started. 198 Otherwise a EV::timer with this value will be started.
112 199
113 When an error occurs or either the timeout or I/O watcher triggers, 200 When an error occurs or either the timeout or I/O watcher triggers,
114 then the callback will be called with the received event set (in 201 then the callback will be called with the received event set (in
115 general you can expect it to be a combination of "EV:ERROR", 202 general you can expect it to be a combination of "EV::ERROR",
116 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 203 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
117 204
118 EV::once doesn't return anything: the watchers stay active till 205 EV::once doesn't return anything: the watchers stay active till
119 either of them triggers, then they will be stopped and freed, and 206 either of them triggers, then they will be stopped and freed, and
120 the callback invoked. 207 the callback invoked.
121 208
209 EV::feed_fd_event ($fd, $revents)
210 $loop->feed_fd_event ($fd, $revents)
211 Feed an event on a file descriptor into EV. EV will react to this
212 call as if the readyness notifications specified by $revents (a
213 combination of "EV::READ" and "EV::WRITE") happened on the file
214 descriptor $fd.
215
216 EV::feed_signal_event ($signal)
217 Feed a signal event into EV. EV will react to this call as if the
218 signal specified by $signal had occured.
219
220 EV::set_io_collect_interval $time
221 $loop->set_io_collect_interval ($time)
222 EV::set_timeout_collect_interval $time
223 $loop->set_timeout_collect_interval ($time)
224 These advanced functions set the minimum block interval when polling
225 for I/O events and the minimum wait interval for timer events. See
226 the libev documentation at
227 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
228 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
229 detailed discussion.
230
122 WATCHER OBJECTS 231WATCHER OBJECTS
123 A watcher is an object that gets created to record your interest in some 232 A watcher is an object that gets created to record your interest in some
124 event. For instance, if you want to wait for STDIN to become readable, 233 event. For instance, if you want to wait for STDIN to become readable,
125 you would create an EV::io watcher for that: 234 you would create an EV::io watcher for that:
126 235
127 my $watcher = EV::io *STDIN, EV::READ, sub { 236 my $watcher = EV::io *STDIN, EV::READ, sub {
128 my ($watcher, $revents) = @_; 237 my ($watcher, $revents) = @_;
129 warn "yeah, STDIN should not be readable without blocking!\n" 238 warn "yeah, STDIN should now be readable without blocking!\n"
130 }; 239 };
131 240
132 All watchers can be active (waiting for events) or inactive (paused). 241 All watchers can be active (waiting for events) or inactive (paused).
133 Only active watchers will have their callbacks invoked. All callbacks 242 Only active watchers will have their callbacks invoked. All callbacks
134 will be called with at least two arguments: the watcher and a bitmask of 243 will be called with at least two arguments: the watcher and a bitmask of
135 received events. 244 received events.
136 245
137 Each watcher type has its associated bit in revents, so you can use the 246 Each watcher type has its associated bit in revents, so you can use the
138 same callback for multiple watchers. The event mask is named after the 247 same callback for multiple watchers. The event mask is named after the
139 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 248 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
140 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 249 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
141 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 250 events (which can set both EV::READ and EV::WRITE bits), and EV::timer
142 (which uses EV::TIMEOUT). 251 (which uses EV::TIMEOUT).
143 252
144 In the rare case where one wants to create a watcher but not start it at 253 In the rare case where one wants to create a watcher but not start it at
145 the same time, each constructor has a variant with a trailing "_ns" in 254 the same time, each constructor has a variant with a trailing "_ns" in
… …
163 stopped watchers). 272 stopped watchers).
164 273
165 $w->stop 274 $w->stop
166 Stop a watcher if it is active. Also clear any pending events 275 Stop a watcher if it is active. Also clear any pending events
167 (events that have been received but that didn't yet result in a 276 (events that have been received but that didn't yet result in a
168 callback invocation), regardless of wether the watcher was active or 277 callback invocation), regardless of whether the watcher was active
169 not. 278 or not.
170 279
171 $bool = $w->is_active 280 $bool = $w->is_active
172 Returns true if the watcher is active, false otherwise. 281 Returns true if the watcher is active, false otherwise.
173 282
174 $current_data = $w->data 283 $current_data = $w->data
… …
197 The default priority of any newly-created watcher is 0. 306 The default priority of any newly-created watcher is 0.
198 307
199 Note that the priority semantics have not yet been fleshed out and 308 Note that the priority semantics have not yet been fleshed out and
200 are subject to almost certain change. 309 are subject to almost certain change.
201 310
202 $w->trigger ($revents) 311 $w->invoke ($revents)
203 Call the callback *now* with the given event mask. 312 Call the callback *now* with the given event mask.
313
314 $w->feed_event ($revents)
315 Feed some events on this watcher into EV. EV will react to this call
316 as if the watcher had received the given $revents mask.
317
318 $revents = $w->clear_pending
319 If the watcher is pending, this function clears its pending status
320 and returns its $revents bitset (as if its callback was invoked). If
321 the watcher isn't pending it does nothing and returns 0.
204 322
205 $previous_state = $w->keepalive ($bool) 323 $previous_state = $w->keepalive ($bool)
206 Normally, "EV::loop" will return when there are no active watchers 324 Normally, "EV::loop" will return when there are no active watchers
207 (which is a "deadlock" because no progress can be made anymore). 325 (which is a "deadlock" because no progress can be made anymore).
208 This is convinient because it allows you to start your watchers (and 326 This is convinient because it allows you to start your watchers (and
209 your jobs), call "EV::loop" once and when it returns you know that 327 your jobs), call "EV::loop" once and when it returns you know that
210 all your jobs are finished (or they forgot to register some watchers 328 all your jobs are finished (or they forgot to register some watchers
211 for their task :). 329 for their task :).
212 330
213 Sometimes, however, this gets in your way, for example when you the 331 Sometimes, however, this gets in your way, for example when the
214 module that calls "EV::loop" (usually the main program) is not the 332 module that calls "EV::loop" (usually the main program) is not the
215 same module as a long-living watcher (for example a DNS client 333 same module as a long-living watcher (for example a DNS client
216 module written by somebody else even). Then you might want any 334 module written by somebody else even). Then you might want any
217 outstanding requests to be handled, but you would not want to keep 335 outstanding requests to be handled, but you would not want to keep
218 "EV::loop" from returning just because you happen to have this 336 "EV::loop" from returning just because you happen to have this
… …
223 returning. 341 returning.
224 342
225 The initial value for keepalive is true (enabled), and you cna 343 The initial value for keepalive is true (enabled), and you cna
226 change it any time. 344 change it any time.
227 345
228 Example: Register an IO watcher for some UDP socket but do not keep 346 Example: Register an I/O watcher for some UDP socket but do not keep
229 the event loop from running just because of that watcher. 347 the event loop from running just because of that watcher.
230 348
231 my $udp_socket = ... 349 my $udp_socket = ...
232 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 350 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
233 $udp_watcher->keepalive (0); 351 $udp_watcher->keepalive (0);
234 352
353 $loop = $w->loop
354 Return the loop that this watcher is attached to.
355
235 WATCHER TYPES 356WATCHER TYPES
236 Each of the following subsections describes a single watcher type. 357 Each of the following subsections describes a single watcher type.
237 358
238 IO WATCHERS - is this file descriptor readable or writable? 359 I/O WATCHERS - is this file descriptor readable or writable?
239 $w = EV::io $fileno_or_fh, $eventmask, $callback 360 $w = EV::io $fileno_or_fh, $eventmask, $callback
240 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 361 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
362 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
363 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
241 As long as the returned watcher object is alive, call the $callback 364 As long as the returned watcher object is alive, call the $callback
242 when at least one of events specified in $eventmask occurs. 365 when at least one of events specified in $eventmask occurs.
243 366
244 The $eventmask can be one or more of these constants ORed together: 367 The $eventmask can be one or more of these constants ORed together:
245 368
… …
262 Returns the previously set event mask and optionally set a new one. 385 Returns the previously set event mask and optionally set a new one.
263 386
264 TIMER WATCHERS - relative and optionally repeating timeouts 387 TIMER WATCHERS - relative and optionally repeating timeouts
265 $w = EV::timer $after, $repeat, $callback 388 $w = EV::timer $after, $repeat, $callback
266 $w = EV::timer_ns $after, $repeat, $callback 389 $w = EV::timer_ns $after, $repeat, $callback
390 $w = $loop->timer ($after, $repeat, $callback)
391 $w = $loop->timer_ns ($after, $repeat, $callback)
267 Calls the callback after $after seconds (which may be fractional). 392 Calls the callback after $after seconds (which may be fractional).
268 If $repeat is non-zero, the timer will be restarted (with the 393 If $repeat is non-zero, the timer will be restarted (with the
269 $repeat value as $after) after the callback returns. 394 $repeat value as $after) after the callback returns.
270 395
271 This means that the callback would be called roughly after $after 396 This means that the callback would be called roughly after $after
… …
307 method on the timeout. 432 method on the timeout.
308 433
309 PERIODIC WATCHERS - to cron or not to cron? 434 PERIODIC WATCHERS - to cron or not to cron?
310 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 435 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
311 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 436 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
437 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
438 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
312 Similar to EV::timer, but is not based on relative timeouts but on 439 Similar to EV::timer, but is not based on relative timeouts but on
313 absolute times. Apart from creating "simple" timers that trigger 440 absolute times. Apart from creating "simple" timers that trigger
314 "at" the specified time, it can also be used for non-drifting 441 "at" the specified time, it can also be used for non-drifting
315 absolute timers and more complex, cron-like, setups that are not 442 absolute timers and more complex, cron-like, setups that are not
316 adversely affected by time jumps (i.e. when the system clock is 443 adversely affected by time jumps (i.e. when the system clock is
317 changed by explicit date -s or other means such as ntpd). It is also 444 changed by explicit date -s or other means such as ntpd). It is also
318 the most complex watcher type in EV. 445 the most complex watcher type in EV.
319 446
320 It has three distinct "modes": 447 It has three distinct "modes":
321 448
322 * absolute timer ($interval = $reschedule_cb = 0) 449 * absolute timer ($interval = $reschedule_cb = 0)
450
323 This time simply fires at the wallclock time $at and doesn't 451 This time simply fires at the wallclock time $at and doesn't
324 repeat. It will not adjust when a time jump occurs, that is, if 452 repeat. It will not adjust when a time jump occurs, that is, if
325 it is to be run at January 1st 2011 then it will run when the 453 it is to be run at January 1st 2011 then it will run when the
326 system time reaches or surpasses this time. 454 system time reaches or surpasses this time.
327 455
328 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 456 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
457
329 In this mode the watcher will always be scheduled to time out at 458 In this mode the watcher will always be scheduled to time out at
330 the next "$at + N * $interval" time (for some integer N) and 459 the next "$at + N * $interval" time (for some integer N) and
331 then repeat, regardless of any time jumps. 460 then repeat, regardless of any time jumps.
332 461
333 This can be used to create timers that do not drift with respect 462 This can be used to create timers that do not drift with respect
… …
342 Another way to think about it (for the mathematically inclined) 471 Another way to think about it (for the mathematically inclined)
343 is that EV::periodic will try to run the callback in this mode 472 is that EV::periodic will try to run the callback in this mode
344 at the next possible time where "$time = $at (mod $interval)", 473 at the next possible time where "$time = $at (mod $interval)",
345 regardless of any time jumps. 474 regardless of any time jumps.
346 475
347 * manual reschedule mode ($reschedule_cb = coderef) 476 * manual reschedule mode ($reschedule_cb = coderef)
477
348 In this mode $interval and $at are both being ignored. Instead, 478 In this mode $interval and $at are both being ignored. Instead,
349 each time the periodic watcher gets scheduled, the reschedule 479 each time the periodic watcher gets scheduled, the reschedule
350 callback ($reschedule_cb) will be called with the watcher as 480 callback ($reschedule_cb) will be called with the watcher as
351 first, and the current time as second argument. 481 first, and the current time as second argument.
352 482
353 *This callback MUST NOT stop or destroy this or any other 483 *This callback MUST NOT stop or destroy this or any other
484 periodic watcher, ever, and MUST NOT call any event loop
354 periodic watcher, ever*. If you need to stop it, return 1e30 and 485 functions or methods*. If you need to stop it, return 1e30 and
355 stop it afterwards. 486 stop it afterwards. You may create and start a "EV::prepare"
487 watcher for this task.
356 488
357 It must return the next time to trigger, based on the passed 489 It must return the next time to trigger, based on the passed
358 time value (that is, the lowest time value larger than to the 490 time value (that is, the lowest time value larger than or equal
359 second argument). It will usually be called just before the 491 to to the second argument). It will usually be called just
360 callback will be triggered, but might be called at other times, 492 before the callback will be triggered, but might be called at
361 too. 493 other times, too.
362 494
363 This can be used to create very complex timers, such as a timer 495 This can be used to create very complex timers, such as a timer
364 that triggers on each midnight, local time (actually 24 hours 496 that triggers on each midnight, local time (actually 24 hours
365 after the last midnight, to keep the example simple. If you know 497 after the last midnight, to keep the example simple. If you know
366 a way to do it correctly in about the same space (without 498 a way to do it correctly in about the same space (without
… …
384 be called at any time. 516 be called at any time.
385 517
386 $w->again 518 $w->again
387 Simply stops and starts the watcher again. 519 Simply stops and starts the watcher again.
388 520
521 $time = $w->at
522 Return the time that the watcher is expected to trigger next.
523
389 SIGNAL WATCHERS - signal me when a signal gets signalled! 524 SIGNAL WATCHERS - signal me when a signal gets signalled!
390 $w = EV::signal $signal, $callback 525 $w = EV::signal $signal, $callback
391 $w = EV::signal_ns $signal, $callback 526 $w = EV::signal_ns $signal, $callback
392 Call the callback when $signal is received (the signal can be 527 Call the callback when $signal is received (the signal can be
393 specified by number or by name, just as with "kill" or %SIG). 528 specified by number or by name, just as with "kill" or %SIG).
… …
410 $old_signum = $w->signal ($new_signal) 545 $old_signum = $w->signal ($new_signal)
411 Returns the previously set signal (always as a number not name) and 546 Returns the previously set signal (always as a number not name) and
412 optionally set a new one. 547 optionally set a new one.
413 548
414 CHILD WATCHERS - watch out for process status changes 549 CHILD WATCHERS - watch out for process status changes
415 $w = EV::child $pid, $callback 550 $w = EV::child $pid, $trace, $callback
416 $w = EV::child_ns $pid, $callback 551 $w = EV::child_ns $pid, $trace, $callback
552 $w = $loop->child ($pid, $trace, $callback)
553 $w = $loop->child_ns ($pid, $trace, $callback)
417 Call the callback when a status change for pid $pid (or any pid if 554 Call the callback when a status change for pid $pid (or any pid if
418 $pid is 0) has been received. More precisely: when the process 555 $pid is 0) has been received (a status change happens when the
556 process terminates or is killed, or, when trace is true,
557 additionally when it is stopped or continued). More precisely: when
419 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 558 the process receives a "SIGCHLD", EV will fetch the outstanding
420 for all changed/zombie children and call the callback. 559 exit/wait status for all changed/zombie children and call the
560 callback.
421 561
422 It is valid (and fully supported) to install a child watcher after a 562 It is valid (and fully supported) to install a child watcher after a
423 child has exited but before the event loop has started its next 563 child has exited but before the event loop has started its next
424 iteration (for example, first you "fork", then the new child process 564 iteration (for example, first you "fork", then the new child process
425 might exit, and only then do you install a child watcher in the 565 might exit, and only then do you install a child watcher in the
… …
432 be called. 572 be called.
433 573
434 The "child_ns" variant doesn't start (activate) the newly created 574 The "child_ns" variant doesn't start (activate) the newly created
435 watcher. 575 watcher.
436 576
437 $w->set ($pid) 577 $w->set ($pid, $trace)
438 Reconfigures the watcher, see the constructor above for details. Can 578 Reconfigures the watcher, see the constructor above for details. Can
439 be called at any time. 579 be called at any time.
440 580
441 $current_pid = $w->pid 581 $current_pid = $w->pid
442 $old_pid = $w->pid ($new_pid)
443 Returns the previously set process id and optionally set a new one. 582 Returns the previously set process id and optionally set a new one.
444 583
445 $exit_status = $w->rstatus 584 $exit_status = $w->rstatus
446 Return the exit/wait status (as returned by waitpid, see the waitpid 585 Return the exit/wait status (as returned by waitpid, see the waitpid
447 entry in perlfunc). 586 entry in perlfunc).
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451 a watcher for all pids). 590 a watcher for all pids).
452 591
453 STAT WATCHERS - did the file attributes just change? 592 STAT WATCHERS - did the file attributes just change?
454 $w = EV::stat $path, $interval, $callback 593 $w = EV::stat $path, $interval, $callback
455 $w = EV::stat_ns $path, $interval, $callback 594 $w = EV::stat_ns $path, $interval, $callback
595 $w = $loop->stat ($path, $interval, $callback)
596 $w = $loop->stat_ns ($path, $interval, $callback)
456 Call the callback when a file status change has been detected on 597 Call the callback when a file status change has been detected on
457 $path. The $path does not need to exist, changing from "path exists" 598 $path. The $path does not need to exist, changing from "path exists"
458 to "path does not exist" is a status change like any other. 599 to "path does not exist" is a status change like any other.
459 600
460 The $interval is a recommended polling interval for systems where 601 The $interval is a recommended polling interval for systems where
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468 resource-intensive. 609 resource-intensive.
469 610
470 The "stat_ns" variant doesn't start (activate) the newly created 611 The "stat_ns" variant doesn't start (activate) the newly created
471 watcher. 612 watcher.
472 613
614 ... = $w->stat
615 This call is very similar to the perl "stat" built-in: It stats
616 (using "lstat") the path specified in the watcher and sets perls
617 stat cache (as well as EV's idea of the current stat values) to the
618 values found.
619
620 In scalar context, a boolean is return indicating success or failure
621 of the stat. In list context, the same 13-value list as with stat is
622 returned (except that the blksize and blocks fields are not
623 reliable).
624
625 In the case of an error, errno is set to "ENOENT" (regardless of the
626 actual error value) and the "nlink" value is forced to zero (if the
627 stat was successful then nlink is guaranteed to be non-zero).
628
629 See also the next two entries for more info.
630
631 ... = $w->attr
632 Just like "$w->stat", but without the initial stat'ing: this returns
633 the values most recently detected by EV. See the next entry for more
634 info.
635
636 ... = $w->prev
637 Just like "$w->stat", but without the initial stat'ing: this returns
638 the previous set of values, before the change.
639
640 That is, when the watcher callback is invoked, "$w->prev" will be
641 set to the values found *before* a change was detected, while
642 "$w->attr" returns the values found leading to the change detection.
643 The difference (if any) between "prev" and "attr" is what triggered
644 the callback.
645
646 If you did something to the filesystem object and do not want to
647 trigger yet another change, you can call "stat" to update EV's idea
648 of what the current attributes are.
649
473 $w->set ($path, $interval) 650 $w->set ($path, $interval)
474 Reconfigures the watcher, see the constructor above for details. Can 651 Reconfigures the watcher, see the constructor above for details. Can
475 be called at any time. 652 be called at any time.
476 653
477 $current_path = $w->path 654 $current_path = $w->path
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484 Can be used to query the actual interval used. 661 Can be used to query the actual interval used.
485 662
486 IDLE WATCHERS - when you've got nothing better to do... 663 IDLE WATCHERS - when you've got nothing better to do...
487 $w = EV::idle $callback 664 $w = EV::idle $callback
488 $w = EV::idle_ns $callback 665 $w = EV::idle_ns $callback
666 $w = $loop->idle ($callback)
667 $w = $loop->idle_ns ($callback)
489 Call the callback when there are no pending io, timer/periodic, 668 Call the callback when there are no other pending watchers of the
490 signal or child events, i.e. when the process is idle. 669 same or higher priority (excluding check, prepare and other idle
670 watchers of the same or lower priority, of course). They are called
671 idle watchers because when the watcher is the highest priority
672 pending event in the process, the process is considered to be idle
673 at that priority.
674
675 If you want a watcher that is only ever called when *no* other
676 events are outstanding you have to set the priority to "EV::MINPRI".
491 677
492 The process will not block as long as any idle watchers are active, 678 The process will not block as long as any idle watchers are active,
493 and they will be called repeatedly until stopped. 679 and they will be called repeatedly until stopped.
680
681 For example, if you have idle watchers at priority 0 and 1, and an
682 I/O watcher at priority 0, then the idle watcher at priority 1 and
683 the I/O watcher will always run when ready. Only when the idle
684 watcher at priority 1 is stopped and the I/O watcher at priority 0
685 is not pending with the 0-priority idle watcher be invoked.
494 686
495 The "idle_ns" variant doesn't start (activate) the newly created 687 The "idle_ns" variant doesn't start (activate) the newly created
496 watcher. 688 watcher.
497 689
498 PREPARE WATCHERS - customise your event loop! 690 PREPARE WATCHERS - customise your event loop!
499 $w = EV::prepare $callback 691 $w = EV::prepare $callback
500 $w = EV::prepare_ns $callback 692 $w = EV::prepare_ns $callback
693 $w = $loop->prepare ($callback)
694 $w = $loop->prepare_ns ($callback)
501 Call the callback just before the process would block. You can still 695 Call the callback just before the process would block. You can still
502 create/modify any watchers at this point. 696 create/modify any watchers at this point.
503 697
504 See the EV::check watcher, below, for explanations and an example. 698 See the EV::check watcher, below, for explanations and an example.
505 699
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507 watcher. 701 watcher.
508 702
509 CHECK WATCHERS - customise your event loop even more! 703 CHECK WATCHERS - customise your event loop even more!
510 $w = EV::check $callback 704 $w = EV::check $callback
511 $w = EV::check_ns $callback 705 $w = EV::check_ns $callback
706 $w = $loop->check ($callback)
707 $w = $loop->check_ns ($callback)
512 Call the callback just after the process wakes up again (after it 708 Call the callback just after the process wakes up again (after it
513 has gathered events), but before any other callbacks have been 709 has gathered events), but before any other callbacks have been
514 invoked. 710 invoked.
515 711
516 This is used to integrate other event-based software into the EV 712 This is used to integrate other event-based software into the EV
… …
527 or return; 723 or return;
528 724
529 # make the dispatcher handle any outstanding stuff 725 # make the dispatcher handle any outstanding stuff
530 ... not shown 726 ... not shown
531 727
532 # create an IO watcher for each and every socket 728 # create an I/O watcher for each and every socket
533 @snmp_watcher = ( 729 @snmp_watcher = (
534 (map { EV::io $_, EV::READ, sub { } } 730 (map { EV::io $_, EV::READ, sub { } }
535 keys %{ $dispatcher->{_descriptors} }), 731 keys %{ $dispatcher->{_descriptors} }),
536 732
537 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 733 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
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565 is done before the event loop blocks next and before "check" watchers 761 is done before the event loop blocks next and before "check" watchers
566 are being called, and only in the child after the fork. 762 are being called, and only in the child after the fork.
567 763
568 $w = EV::fork $callback 764 $w = EV::fork $callback
569 $w = EV::fork_ns $callback 765 $w = EV::fork_ns $callback
766 $w = $loop->fork ($callback)
767 $w = $loop->fork_ns ($callback)
570 Call the callback before the event loop is resumed in the child 768 Call the callback before the event loop is resumed in the child
571 process after a fork. 769 process after a fork.
572 770
573 The "fork_ns" variant doesn't start (activate) the newly created 771 The "fork_ns" variant doesn't start (activate) the newly created
574 watcher. 772 watcher.
773
774 EMBED WATCHERS - when one backend isn't enough...
775 This is a rather advanced watcher type that lets you embed one event
776 loop into another (currently only IO events are supported in the
777 embedded loop, other types of watchers might be handled in a delayed or
778 incorrect fashion and must not be used).
779
780 See the libev documentation at
781 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
782 _when_one_backend_> (locally installed as EV::libev) for more details.
783
784 In short, this watcher is most useful on BSD systems without working
785 kqueue to still be able to handle a large number of sockets:
786
787 my $socket_loop;
788
789 # check wether we use SELECT or POLL _and_ KQUEUE is supported
790 if (
791 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
792 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
793 ) {
794 # use kqueue for sockets
795 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
796 }
797
798 # use the default loop otherwise
799 $socket_loop ||= EV::default_loop;
800
801 $w = EV::embed $otherloop[, $callback]
802 $w = EV::embed_ns $otherloop[, $callback]
803 $w = $loop->embed ($otherloop[, $callback])
804 $w = $loop->embed_ns ($otherloop[, $callback])
805 Call the callback when the embedded event loop ($otherloop) has any
806 I/O activity. The $callback is optional: if it is missing, then the
807 embedded event loop will be managed automatically (which is
808 recommended), otherwise you have to invoke "sweep" yourself.
809
810 The "embed_ns" variant doesn't start (activate) the newly created
811 watcher.
812
813 ASYNC WATCHERS - how to wake up another event loop
814 Async watchers are provided by EV, but have little use in perl directly,
815 as perl neither supports threads nor direct access to signal handlers or
816 other contexts where they could be of value.
817
818 It is, however, possible to use them from the XS level.
819
820 Please see the libev documentation for further details.
821
822 $w = EV::async $callback
823 $w = EV::async_ns $callback
824 $w->send
825 $bool = $w->async_pending
826
827PERL SIGNALS
828 While Perl signal handling (%SIG) is not affected by EV, the behaviour
829 with EV is as the same as any other C library: Perl-signals will only be
830 handled when Perl runs, which means your signal handler might be invoked
831 only the next time an event callback is invoked.
832
833 The solution is to use EV signal watchers (see "EV::signal"), which will
834 ensure proper operations with regards to other event watchers.
835
836 If you cannot do this for whatever reason, you can also force a watcher
837 to be called on every event loop iteration by installing a "EV::check"
838 watcher:
839
840 my $async_check = EV::check sub { };
841
842 This ensures that perl gets into control for a short time to handle any
843 pending signals, and also ensures (slightly) slower overall operation.
575 844
576THREADS 845THREADS
577 Threads are not supported by this module in any way. Perl pseudo-threads 846 Threads are not supported by this module in any way. Perl pseudo-threads
578 is evil stuff and must die. As soon as Perl gains real threads I will 847 is evil stuff and must die. As soon as Perl gains real threads I will
579 work on thread support for it. 848 work on thread support for it.
… …
594 863
595 On win32, there is no notion of fork so all this doesn't apply, of 864 On win32, there is no notion of fork so all this doesn't apply, of
596 course. 865 course.
597 866
598SEE ALSO 867SEE ALSO
599 EV::DNS. 868 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
869 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
870 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
871 agnostic and portable event driven programming.
600 872
601AUTHOR 873AUTHOR
602 Marc Lehmann <schmorp@schmorp.de> 874 Marc Lehmann <schmorp@schmorp.de>
603 http://home.schmorp.de/ 875 http://home.schmorp.de/
604 876

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