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Revision 1.36 by root, Thu Oct 21 02:46:59 2010 UTC

1NAME 1NAME
2 EV - perl interface to libev, a high performance full-featured event 2 EV - perl interface to libev, a high performance full-featured event
3 loop 3 loop
4 4
5SYNOPSIS 5SYNOPSIS
6 use EV; 6 use EV;
7
8 # TIMERS
9
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
7 38
8 # TIMERS 39 my $w = EV::child 666, 0, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
9 43
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
38
39 my $w = EV::child 666, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
43
44 # STAT CHANGES 44 # STAT CHANGES
45 my $w = EV::stat "/etc/passwd", 10, sub { 45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_; 46 my ($w, $revents) = @_;
47 warn $w->path, " has changed somehow.\n"; 47 warn $w->path, " has changed somehow.\n";
48 }; 48 };
49 49
50 # MAINLOOP 50 # MAINLOOP
51 EV::loop; # loop until EV::unloop is called or all watchers stop 51 EV::loop; # loop until EV::unloop is called or all watchers stop
52 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 52 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
53 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 53 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
54
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". 70 discussion on the available backends, or how to force a specific backend
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 MODULE EXPORTS
81 This module does not export any symbols.
82
83EVENT LOOPS
84 EV supports multiple event loops: There is a single "default event loop"
85 that can handle everything including signals and child watchers, and any
86 number of "dynamic event loops" that can use different backends (with
87 various limitations), but no child and signal watchers.
88
89 You do not have to do anything to create the default event loop: When
90 the module is loaded a suitable backend is selected on the premise of
91 selecting a working backend (which for example rules out kqueue on most
92 BSDs). Modules should, unless they have "special needs" always use the
93 default loop as this is fastest (perl-wise), best supported by other
94 modules (e.g. AnyEvent or Coro) and most portable event loop.
95
96 For specific programs you can create additional event loops dynamically.
97
98 If you want to take advantage of kqueue (which often works properly for
99 sockets only) even though the default loop doesn't enable it, you can
100 *embed* a kqueue loop into the default loop: running the default loop
101 will then also service the kqueue loop to some extent. See the example
102 in the section about embed watchers for an example on how to achieve
103 that.
104
105 $loop = new EV::Loop [$flags]
106 Create a new event loop as per the specified flags. Please refer to
107 the "ev_loop_new ()" function description in the libev documentation
108 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
109 ONS>, or locally-installed as EV::libev manpage) for more info.
110
111 The loop will automatically be destroyed when it is no longer
112 referenced by any watcher and the loop object goes out of scope.
113
114 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
115 is recommended, as only the default event loop is protected by this
116 module. If you *are* embedding this loop in the default loop, this
117 is not necessary, as "EV::embed" automatically does the right thing
118 on fork.
119
120 $loop->loop_fork
121 Must be called after a fork in the child, before entering or
122 continuing the event loop. An alternative is to use
123 "EV::FLAG_FORKCHECK" which calls this function automatically, at
124 some performance loss (refer to the libev documentation).
125
126 $loop->loop_verify
127 Calls "ev_verify" to make internal consistency checks (for debugging
128 libev) and abort the program if any data structures were found to be
129 corrupted.
130
131 $loop = EV::default_loop [$flags]
132 Return the default loop (which is a singleton object). Since this
133 module already creates the default loop with default flags,
134 specifying flags here will not have any effect unless you destroy
135 the default loop first, which isn't supported. So in short: don't do
136 it, and if you break it, you get to keep the pieces.
62 137
63BASIC INTERFACE 138BASIC INTERFACE
64 $EV::DIED 139 $EV::DIED
65 Must contain a reference to a function that is called when a 140 Must contain a reference to a function that is called when a
66 callback throws an exception (with $@ containing thr error). The 141 callback throws an exception (with $@ containing the error). The
67 default prints an informative message and continues. 142 default prints an informative message and continues.
68 143
69 If this callback throws an exception it will be silently ignored. 144 If this callback throws an exception it will be silently ignored.
145
146 $flags = EV::supported_backends
147 $flags = EV::recommended_backends
148 $flags = EV::embeddable_backends
149 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
150 this instance of EV, the set of recommended backends (supposed to be
151 good) for this platform and the set of embeddable backends (see
152 EMBED WATCHERS).
153
154 EV::sleep $seconds
155 Block the process for the given number of (fractional) seconds.
70 156
71 $time = EV::time 157 $time = EV::time
72 Returns the current time in (fractional) seconds since the epoch. 158 Returns the current time in (fractional) seconds since the epoch.
73 159
74 $time = EV::now 160 $time = EV::now
161 $time = $loop->now
75 Returns the time the last event loop iteration has been started. 162 Returns the time the last event loop iteration has been started.
76 This is the time that (relative) timers are based on, and refering 163 This is the time that (relative) timers are based on, and referring
77 to it is usually faster then calling EV::time. 164 to it is usually faster then calling EV::time.
78 165
79 $method = EV::method 166 EV::now_update
167 $loop->now_update
168 Establishes the current time by querying the kernel, updating the
169 time returned by "EV::now" in the progress. This is a costly
170 operation and is usually done automatically within "EV::loop".
171
172 This function is rarely useful, but when some event callback runs
173 for a very long time without entering the event loop, updating
174 libev's idea of the current time is a good idea.
175
176 EV::suspend
177 $loop->suspend
178 EV::resume
179 $loop->resume
180 These two functions suspend and resume a loop, for use when the loop
181 is not used for a while and timeouts should not be processed.
182
183 A typical use case would be an interactive program such as a game:
184 When the user presses "^Z" to suspend the game and resumes it an
185 hour later it would be best to handle timeouts as if no time had
186 actually passed while the program was suspended. This can be
187 achieved by calling "suspend" in your "SIGTSTP" handler, sending
188 yourself a "SIGSTOP" and calling "resume" directly afterwards to
189 resume timer processing.
190
191 Effectively, all "timer" watchers will be delayed by the time spend
192 between "suspend" and "resume", and all "periodic" watchers will be
193 rescheduled (that is, they will lose any events that would have
194 occured while suspended).
195
196 After calling "suspend" you must not call *any* function on the
197 given loop other than "resume", and you must not call "resume"
198 without a previous call to "suspend".
199
200 Calling "suspend"/"resume" has the side effect of updating the event
201 loop time (see "now_update").
202
203 $backend = EV::backend
204 $backend = $loop->backend
80 Returns an integer describing the backend used by libev 205 Returns an integer describing the backend used by libev
81 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 206 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
82 207
83 EV::loop [$flags] 208 EV::loop [$flags]
209 $loop->loop ([$flags])
84 Begin checking for events and calling callbacks. It returns when a 210 Begin checking for events and calling callbacks. It returns when a
85 callback calls EV::unloop. 211 callback calls EV::unloop.
86 212
87 The $flags argument can be one of the following: 213 The $flags argument can be one of the following:
88 214
89 0 as above 215 0 as above
90 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 216 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
91 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 217 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
92 218
93 EV::unloop [$how] 219 EV::unloop [$how]
220 $loop->unloop ([$how])
94 When called with no arguments or an argument of EV::UNLOOP_ONE, 221 When called with no arguments or an argument of EV::UNLOOP_ONE,
95 makes the innermost call to EV::loop return. 222 makes the innermost call to EV::loop return.
96 223
97 When called with an argument of EV::UNLOOP_ALL, all calls to 224 When called with an argument of EV::UNLOOP_ALL, all calls to
98 EV::loop will return as fast as possible. 225 EV::loop will return as fast as possible.
99 226
100 $count = EV::loop_count 227 $count = EV::loop_count
228 $count = $loop->loop_count
101 Return the number of times the event loop has polled for new events. 229 Return the number of times the event loop has polled for new events.
102 Sometiems useful as a generation counter. 230 Sometimes useful as a generation counter.
103 231
104 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 232 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
233 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
105 This function rolls together an I/O and a timer watcher for a single 234 This function rolls together an I/O and a timer watcher for a single
106 one-shot event without the need for managing a watcher object. 235 one-shot event without the need for managing a watcher object.
107 236
108 If $fh_or_undef is a filehandle or file descriptor, then $events 237 If $fh_or_undef is a filehandle or file descriptor, then $events
109 must be a bitset containing either "EV::READ", "EV::WRITE" or 238 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
114 If timeout is "undef" or negative, then there will be no timeout. 243 If timeout is "undef" or negative, then there will be no timeout.
115 Otherwise a EV::timer with this value will be started. 244 Otherwise a EV::timer with this value will be started.
116 245
117 When an error occurs or either the timeout or I/O watcher triggers, 246 When an error occurs or either the timeout or I/O watcher triggers,
118 then the callback will be called with the received event set (in 247 then the callback will be called with the received event set (in
119 general you can expect it to be a combination of "EV:ERROR", 248 general you can expect it to be a combination of "EV::ERROR",
120 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 249 "EV::READ", "EV::WRITE" and "EV::TIMER").
121 250
122 EV::once doesn't return anything: the watchers stay active till 251 EV::once doesn't return anything: the watchers stay active till
123 either of them triggers, then they will be stopped and freed, and 252 either of them triggers, then they will be stopped and freed, and
124 the callback invoked. 253 the callback invoked.
125 254
255 EV::feed_fd_event ($fd, $revents)
256 $loop->feed_fd_event ($fd, $revents)
257 Feed an event on a file descriptor into EV. EV will react to this
258 call as if the readyness notifications specified by $revents (a
259 combination of "EV::READ" and "EV::WRITE") happened on the file
260 descriptor $fd.
261
262 EV::feed_signal_event ($signal)
263 Feed a signal event into EV. EV will react to this call as if the
264 signal specified by $signal had occured.
265
266 EV::set_io_collect_interval $time
267 $loop->set_io_collect_interval ($time)
268 EV::set_timeout_collect_interval $time
269 $loop->set_timeout_collect_interval ($time)
270 These advanced functions set the minimum block interval when polling
271 for I/O events and the minimum wait interval for timer events. See
272 the libev documentation at
273 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
274 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
275 detailed discussion.
276
277 $count = EV::pending_count
278 $count = $loop->pending_count
279 Returns the number of currently pending watchers.
280
281 EV::invoke_pending
282 $loop->invoke_pending
283 Invoke all currently pending watchers.
284
126 WATCHER OBJECTS 285WATCHER OBJECTS
127 A watcher is an object that gets created to record your interest in some 286 A watcher is an object that gets created to record your interest in some
128 event. For instance, if you want to wait for STDIN to become readable, 287 event. For instance, if you want to wait for STDIN to become readable,
129 you would create an EV::io watcher for that: 288 you would create an EV::io watcher for that:
130 289
131 my $watcher = EV::io *STDIN, EV::READ, sub { 290 my $watcher = EV::io *STDIN, EV::READ, sub {
132 my ($watcher, $revents) = @_; 291 my ($watcher, $revents) = @_;
133 warn "yeah, STDIN should not be readable without blocking!\n" 292 warn "yeah, STDIN should now be readable without blocking!\n"
134 }; 293 };
135 294
136 All watchers can be active (waiting for events) or inactive (paused). 295 All watchers can be active (waiting for events) or inactive (paused).
137 Only active watchers will have their callbacks invoked. All callbacks 296 Only active watchers will have their callbacks invoked. All callbacks
138 will be called with at least two arguments: the watcher and a bitmask of 297 will be called with at least two arguments: the watcher and a bitmask of
139 received events. 298 received events.
140 299
141 Each watcher type has its associated bit in revents, so you can use the 300 Each watcher type has its associated bit in revents, so you can use the
142 same callback for multiple watchers. The event mask is named after the 301 same callback for multiple watchers. The event mask is named after the
143 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 302 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
144 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 303 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
145 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 304 events (which can set both EV::READ and EV::WRITE bits).
146 (which uses EV::TIMEOUT).
147 305
148 In the rare case where one wants to create a watcher but not start it at 306 In the rare case where one wants to create a watcher but not start it at
149 the same time, each constructor has a variant with a trailing "_ns" in 307 the same time, each constructor has a variant with a trailing "_ns" in
150 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 308 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
151 309
… …
167 stopped watchers). 325 stopped watchers).
168 326
169 $w->stop 327 $w->stop
170 Stop a watcher if it is active. Also clear any pending events 328 Stop a watcher if it is active. Also clear any pending events
171 (events that have been received but that didn't yet result in a 329 (events that have been received but that didn't yet result in a
172 callback invocation), regardless of wether the watcher was active or 330 callback invocation), regardless of whether the watcher was active
173 not. 331 or not.
174 332
175 $bool = $w->is_active 333 $bool = $w->is_active
176 Returns true if the watcher is active, false otherwise. 334 Returns true if the watcher is active, false otherwise.
177 335
178 $current_data = $w->data 336 $current_data = $w->data
… …
201 The default priority of any newly-created watcher is 0. 359 The default priority of any newly-created watcher is 0.
202 360
203 Note that the priority semantics have not yet been fleshed out and 361 Note that the priority semantics have not yet been fleshed out and
204 are subject to almost certain change. 362 are subject to almost certain change.
205 363
206 $w->trigger ($revents) 364 $w->invoke ($revents)
207 Call the callback *now* with the given event mask. 365 Call the callback *now* with the given event mask.
366
367 $w->feed_event ($revents)
368 Feed some events on this watcher into EV. EV will react to this call
369 as if the watcher had received the given $revents mask.
370
371 $revents = $w->clear_pending
372 If the watcher is pending, this function clears its pending status
373 and returns its $revents bitset (as if its callback was invoked). If
374 the watcher isn't pending it does nothing and returns 0.
208 375
209 $previous_state = $w->keepalive ($bool) 376 $previous_state = $w->keepalive ($bool)
210 Normally, "EV::loop" will return when there are no active watchers 377 Normally, "EV::loop" will return when there are no active watchers
211 (which is a "deadlock" because no progress can be made anymore). 378 (which is a "deadlock" because no progress can be made anymore).
212 This is convinient because it allows you to start your watchers (and 379 This is convenient because it allows you to start your watchers (and
213 your jobs), call "EV::loop" once and when it returns you know that 380 your jobs), call "EV::loop" once and when it returns you know that
214 all your jobs are finished (or they forgot to register some watchers 381 all your jobs are finished (or they forgot to register some watchers
215 for their task :). 382 for their task :).
216 383
217 Sometimes, however, this gets in your way, for example when you the 384 Sometimes, however, this gets in your way, for example when the
218 module that calls "EV::loop" (usually the main program) is not the 385 module that calls "EV::loop" (usually the main program) is not the
219 same module as a long-living watcher (for example a DNS client 386 same module as a long-living watcher (for example a DNS client
220 module written by somebody else even). Then you might want any 387 module written by somebody else even). Then you might want any
221 outstanding requests to be handled, but you would not want to keep 388 outstanding requests to be handled, but you would not want to keep
222 "EV::loop" from returning just because you happen to have this 389 "EV::loop" from returning just because you happen to have this
… …
224 391
225 In this case you can clear the keepalive status, which means that 392 In this case you can clear the keepalive status, which means that
226 even though your watcher is active, it won't keep "EV::loop" from 393 even though your watcher is active, it won't keep "EV::loop" from
227 returning. 394 returning.
228 395
229 The initial value for keepalive is true (enabled), and you cna 396 The initial value for keepalive is true (enabled), and you can
230 change it any time. 397 change it any time.
231 398
232 Example: Register an IO watcher for some UDP socket but do not keep 399 Example: Register an I/O watcher for some UDP socket but do not keep
233 the event loop from running just because of that watcher. 400 the event loop from running just because of that watcher.
234 401
235 my $udp_socket = ... 402 my $udp_socket = ...
236 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 403 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
237 $udp_watcher->keepalive (0); 404 $udp_watcher->keepalive (0);
238 405
406 $loop = $w->loop
407 Return the loop that this watcher is attached to.
408
239 WATCHER TYPES 409WATCHER TYPES
240 Each of the following subsections describes a single watcher type. 410 Each of the following subsections describes a single watcher type.
241 411
242 IO WATCHERS - is this file descriptor readable or writable? 412 I/O WATCHERS - is this file descriptor readable or writable?
243 $w = EV::io $fileno_or_fh, $eventmask, $callback 413 $w = EV::io $fileno_or_fh, $eventmask, $callback
244 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 414 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
415 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
416 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
245 As long as the returned watcher object is alive, call the $callback 417 As long as the returned watcher object is alive, call the $callback
246 when at least one of events specified in $eventmask occurs. 418 when at least one of events specified in $eventmask occurs.
247 419
248 The $eventmask can be one or more of these constants ORed together: 420 The $eventmask can be one or more of these constants ORed together:
249 421
… …
266 Returns the previously set event mask and optionally set a new one. 438 Returns the previously set event mask and optionally set a new one.
267 439
268 TIMER WATCHERS - relative and optionally repeating timeouts 440 TIMER WATCHERS - relative and optionally repeating timeouts
269 $w = EV::timer $after, $repeat, $callback 441 $w = EV::timer $after, $repeat, $callback
270 $w = EV::timer_ns $after, $repeat, $callback 442 $w = EV::timer_ns $after, $repeat, $callback
443 $w = $loop->timer ($after, $repeat, $callback)
444 $w = $loop->timer_ns ($after, $repeat, $callback)
271 Calls the callback after $after seconds (which may be fractional). 445 Calls the callback after $after seconds (which may be fractional).
272 If $repeat is non-zero, the timer will be restarted (with the 446 If $repeat is non-zero, the timer will be restarted (with the
273 $repeat value as $after) after the callback returns. 447 $repeat value as $after) after the callback returns.
274 448
275 This means that the callback would be called roughly after $after 449 This means that the callback would be called roughly after $after
… …
311 method on the timeout. 485 method on the timeout.
312 486
313 PERIODIC WATCHERS - to cron or not to cron? 487 PERIODIC WATCHERS - to cron or not to cron?
314 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 488 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
315 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 489 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
490 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
491 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
316 Similar to EV::timer, but is not based on relative timeouts but on 492 Similar to EV::timer, but is not based on relative timeouts but on
317 absolute times. Apart from creating "simple" timers that trigger 493 absolute times. Apart from creating "simple" timers that trigger
318 "at" the specified time, it can also be used for non-drifting 494 "at" the specified time, it can also be used for non-drifting
319 absolute timers and more complex, cron-like, setups that are not 495 absolute timers and more complex, cron-like, setups that are not
320 adversely affected by time jumps (i.e. when the system clock is 496 adversely affected by time jumps (i.e. when the system clock is
321 changed by explicit date -s or other means such as ntpd). It is also 497 changed by explicit date -s or other means such as ntpd). It is also
322 the most complex watcher type in EV. 498 the most complex watcher type in EV.
323 499
324 It has three distinct "modes": 500 It has three distinct "modes":
325 501
326 * absolute timer ($interval = $reschedule_cb = 0) 502 * absolute timer ($interval = $reschedule_cb = 0)
503
327 This time simply fires at the wallclock time $at and doesn't 504 This time simply fires at the wallclock time $at and doesn't
328 repeat. It will not adjust when a time jump occurs, that is, if 505 repeat. It will not adjust when a time jump occurs, that is, if
329 it is to be run at January 1st 2011 then it will run when the 506 it is to be run at January 1st 2011 then it will run when the
330 system time reaches or surpasses this time. 507 system time reaches or surpasses this time.
331 508
332 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 509 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
510
333 In this mode the watcher will always be scheduled to time out at 511 In this mode the watcher will always be scheduled to time out at
334 the next "$at + N * $interval" time (for some integer N) and 512 the next "$at + N * $interval" time (for some integer N) and
335 then repeat, regardless of any time jumps. 513 then repeat, regardless of any time jumps.
336 514
337 This can be used to create timers that do not drift with respect 515 This can be used to create timers that do not drift with respect
… …
346 Another way to think about it (for the mathematically inclined) 524 Another way to think about it (for the mathematically inclined)
347 is that EV::periodic will try to run the callback in this mode 525 is that EV::periodic will try to run the callback in this mode
348 at the next possible time where "$time = $at (mod $interval)", 526 at the next possible time where "$time = $at (mod $interval)",
349 regardless of any time jumps. 527 regardless of any time jumps.
350 528
351 * manual reschedule mode ($reschedule_cb = coderef) 529 * manual reschedule mode ($reschedule_cb = coderef)
530
352 In this mode $interval and $at are both being ignored. Instead, 531 In this mode $interval and $at are both being ignored. Instead,
353 each time the periodic watcher gets scheduled, the reschedule 532 each time the periodic watcher gets scheduled, the reschedule
354 callback ($reschedule_cb) will be called with the watcher as 533 callback ($reschedule_cb) will be called with the watcher as
355 first, and the current time as second argument. 534 first, and the current time as second argument.
356 535
357 *This callback MUST NOT stop or destroy this or any other 536 *This callback MUST NOT stop or destroy this or any other
537 periodic watcher, ever, and MUST NOT call any event loop
358 periodic watcher, ever*. If you need to stop it, return 1e30 and 538 functions or methods*. If you need to stop it, return 1e30 and
359 stop it afterwards. 539 stop it afterwards. You may create and start a "EV::prepare"
540 watcher for this task.
360 541
361 It must return the next time to trigger, based on the passed 542 It must return the next time to trigger, based on the passed
362 time value (that is, the lowest time value larger than to the 543 time value (that is, the lowest time value larger than or equal
363 second argument). It will usually be called just before the 544 to to the second argument). It will usually be called just
364 callback will be triggered, but might be called at other times, 545 before the callback will be triggered, but might be called at
365 too. 546 other times, too.
366 547
367 This can be used to create very complex timers, such as a timer 548 This can be used to create very complex timers, such as a timer
368 that triggers on each midnight, local time (actually 24 hours 549 that triggers on each midnight, local time (actually 24 hours
369 after the last midnight, to keep the example simple. If you know 550 after the last midnight, to keep the example simple. If you know
370 a way to do it correctly in about the same space (without 551 a way to do it correctly in about the same space (without
… …
388 be called at any time. 569 be called at any time.
389 570
390 $w->again 571 $w->again
391 Simply stops and starts the watcher again. 572 Simply stops and starts the watcher again.
392 573
574 $time = $w->at
575 Return the time that the watcher is expected to trigger next.
576
393 SIGNAL WATCHERS - signal me when a signal gets signalled! 577 SIGNAL WATCHERS - signal me when a signal gets signalled!
394 $w = EV::signal $signal, $callback 578 $w = EV::signal $signal, $callback
395 $w = EV::signal_ns $signal, $callback 579 $w = EV::signal_ns $signal, $callback
580 $w = $loop->signal ($signal, $callback)
581 $w = $loop->signal_ns ($signal, $callback)
396 Call the callback when $signal is received (the signal can be 582 Call the callback when $signal is received (the signal can be
397 specified by number or by name, just as with "kill" or %SIG). 583 specified by number or by name, just as with "kill" or %SIG).
584
585 Only one event loop can grab a given signal - attempting to grab the
586 same signal from two EV loops will crash the program immediately or
587 cause data corruption.
398 588
399 EV will grab the signal for the process (the kernel only allows one 589 EV will grab the signal for the process (the kernel only allows one
400 component to receive a signal at a time) when you start a signal 590 component to receive a signal at a time) when you start a signal
401 watcher, and removes it again when you stop it. Perl does the same 591 watcher, and removes it again when you stop it. Perl does the same
402 when you add/remove callbacks to %SIG, so watch out. 592 when you add/remove callbacks to %SIG, so watch out.
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414 $old_signum = $w->signal ($new_signal) 604 $old_signum = $w->signal ($new_signal)
415 Returns the previously set signal (always as a number not name) and 605 Returns the previously set signal (always as a number not name) and
416 optionally set a new one. 606 optionally set a new one.
417 607
418 CHILD WATCHERS - watch out for process status changes 608 CHILD WATCHERS - watch out for process status changes
419 $w = EV::child $pid, $callback 609 $w = EV::child $pid, $trace, $callback
420 $w = EV::child_ns $pid, $callback 610 $w = EV::child_ns $pid, $trace, $callback
611 $w = $loop->child ($pid, $trace, $callback)
612 $w = $loop->child_ns ($pid, $trace, $callback)
421 Call the callback when a status change for pid $pid (or any pid if 613 Call the callback when a status change for pid $pid (or any pid if
422 $pid is 0) has been received. More precisely: when the process 614 $pid is 0) has been received (a status change happens when the
615 process terminates or is killed, or, when trace is true,
616 additionally when it is stopped or continued). More precisely: when
423 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 617 the process receives a "SIGCHLD", EV will fetch the outstanding
424 for all changed/zombie children and call the callback. 618 exit/wait status for all changed/zombie children and call the
619 callback.
425 620
426 It is valid (and fully supported) to install a child watcher after a 621 It is valid (and fully supported) to install a child watcher after a
427 child has exited but before the event loop has started its next 622 child has exited but before the event loop has started its next
428 iteration (for example, first you "fork", then the new child process 623 iteration (for example, first you "fork", then the new child process
429 might exit, and only then do you install a child watcher in the 624 might exit, and only then do you install a child watcher in the
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436 be called. 631 be called.
437 632
438 The "child_ns" variant doesn't start (activate) the newly created 633 The "child_ns" variant doesn't start (activate) the newly created
439 watcher. 634 watcher.
440 635
441 $w->set ($pid) 636 $w->set ($pid, $trace)
442 Reconfigures the watcher, see the constructor above for details. Can 637 Reconfigures the watcher, see the constructor above for details. Can
443 be called at any time. 638 be called at any time.
444 639
445 $current_pid = $w->pid 640 $current_pid = $w->pid
446 $old_pid = $w->pid ($new_pid)
447 Returns the previously set process id and optionally set a new one. 641 Returns the previously set process id and optionally set a new one.
448 642
449 $exit_status = $w->rstatus 643 $exit_status = $w->rstatus
450 Return the exit/wait status (as returned by waitpid, see the waitpid 644 Return the exit/wait status (as returned by waitpid, see the waitpid
451 entry in perlfunc). 645 entry in perlfunc).
… …
455 a watcher for all pids). 649 a watcher for all pids).
456 650
457 STAT WATCHERS - did the file attributes just change? 651 STAT WATCHERS - did the file attributes just change?
458 $w = EV::stat $path, $interval, $callback 652 $w = EV::stat $path, $interval, $callback
459 $w = EV::stat_ns $path, $interval, $callback 653 $w = EV::stat_ns $path, $interval, $callback
654 $w = $loop->stat ($path, $interval, $callback)
655 $w = $loop->stat_ns ($path, $interval, $callback)
460 Call the callback when a file status change has been detected on 656 Call the callback when a file status change has been detected on
461 $path. The $path does not need to exist, changing from "path exists" 657 $path. The $path does not need to exist, changing from "path exists"
462 to "path does not exist" is a status change like any other. 658 to "path does not exist" is a status change like any other.
463 659
464 The $interval is a recommended polling interval for systems where 660 The $interval is a recommended polling interval for systems where
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524 Can be used to query the actual interval used. 720 Can be used to query the actual interval used.
525 721
526 IDLE WATCHERS - when you've got nothing better to do... 722 IDLE WATCHERS - when you've got nothing better to do...
527 $w = EV::idle $callback 723 $w = EV::idle $callback
528 $w = EV::idle_ns $callback 724 $w = EV::idle_ns $callback
725 $w = $loop->idle ($callback)
726 $w = $loop->idle_ns ($callback)
529 Call the callback when there are no pending io, timer/periodic, 727 Call the callback when there are no other pending watchers of the
530 signal or child events, i.e. when the process is idle. 728 same or higher priority (excluding check, prepare and other idle
729 watchers of the same or lower priority, of course). They are called
730 idle watchers because when the watcher is the highest priority
731 pending event in the process, the process is considered to be idle
732 at that priority.
733
734 If you want a watcher that is only ever called when *no* other
735 events are outstanding you have to set the priority to "EV::MINPRI".
531 736
532 The process will not block as long as any idle watchers are active, 737 The process will not block as long as any idle watchers are active,
533 and they will be called repeatedly until stopped. 738 and they will be called repeatedly until stopped.
739
740 For example, if you have idle watchers at priority 0 and 1, and an
741 I/O watcher at priority 0, then the idle watcher at priority 1 and
742 the I/O watcher will always run when ready. Only when the idle
743 watcher at priority 1 is stopped and the I/O watcher at priority 0
744 is not pending with the 0-priority idle watcher be invoked.
534 745
535 The "idle_ns" variant doesn't start (activate) the newly created 746 The "idle_ns" variant doesn't start (activate) the newly created
536 watcher. 747 watcher.
537 748
538 PREPARE WATCHERS - customise your event loop! 749 PREPARE WATCHERS - customise your event loop!
539 $w = EV::prepare $callback 750 $w = EV::prepare $callback
540 $w = EV::prepare_ns $callback 751 $w = EV::prepare_ns $callback
752 $w = $loop->prepare ($callback)
753 $w = $loop->prepare_ns ($callback)
541 Call the callback just before the process would block. You can still 754 Call the callback just before the process would block. You can still
542 create/modify any watchers at this point. 755 create/modify any watchers at this point.
543 756
544 See the EV::check watcher, below, for explanations and an example. 757 See the EV::check watcher, below, for explanations and an example.
545 758
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547 watcher. 760 watcher.
548 761
549 CHECK WATCHERS - customise your event loop even more! 762 CHECK WATCHERS - customise your event loop even more!
550 $w = EV::check $callback 763 $w = EV::check $callback
551 $w = EV::check_ns $callback 764 $w = EV::check_ns $callback
765 $w = $loop->check ($callback)
766 $w = $loop->check_ns ($callback)
552 Call the callback just after the process wakes up again (after it 767 Call the callback just after the process wakes up again (after it
553 has gathered events), but before any other callbacks have been 768 has gathered events), but before any other callbacks have been
554 invoked. 769 invoked.
555 770
556 This is used to integrate other event-based software into the EV 771 This is used to integrate other event-based software into the EV
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567 or return; 782 or return;
568 783
569 # make the dispatcher handle any outstanding stuff 784 # make the dispatcher handle any outstanding stuff
570 ... not shown 785 ... not shown
571 786
572 # create an IO watcher for each and every socket 787 # create an I/O watcher for each and every socket
573 @snmp_watcher = ( 788 @snmp_watcher = (
574 (map { EV::io $_, EV::READ, sub { } } 789 (map { EV::io $_, EV::READ, sub { } }
575 keys %{ $dispatcher->{_descriptors} }), 790 keys %{ $dispatcher->{_descriptors} }),
576 791
577 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 792 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
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592 # make the dispatcher handle any new stuff 807 # make the dispatcher handle any new stuff
593 ... not shown 808 ... not shown
594 }; 809 };
595 810
596 The callbacks of the created watchers will not be called as the 811 The callbacks of the created watchers will not be called as the
597 watchers are destroyed before this cna happen (remember EV::check 812 watchers are destroyed before this can happen (remember EV::check
598 gets called first). 813 gets called first).
599 814
600 The "check_ns" variant doesn't start (activate) the newly created 815 The "check_ns" variant doesn't start (activate) the newly created
601 watcher. 816 watcher.
602 817
… …
605 is done before the event loop blocks next and before "check" watchers 820 is done before the event loop blocks next and before "check" watchers
606 are being called, and only in the child after the fork. 821 are being called, and only in the child after the fork.
607 822
608 $w = EV::fork $callback 823 $w = EV::fork $callback
609 $w = EV::fork_ns $callback 824 $w = EV::fork_ns $callback
825 $w = $loop->fork ($callback)
826 $w = $loop->fork_ns ($callback)
610 Call the callback before the event loop is resumed in the child 827 Call the callback before the event loop is resumed in the child
611 process after a fork. 828 process after a fork.
612 829
613 The "fork_ns" variant doesn't start (activate) the newly created 830 The "fork_ns" variant doesn't start (activate) the newly created
614 watcher. 831 watcher.
615 832
833 EMBED WATCHERS - when one backend isn't enough...
834 This is a rather advanced watcher type that lets you embed one event
835 loop into another (currently only IO events are supported in the
836 embedded loop, other types of watchers might be handled in a delayed or
837 incorrect fashion and must not be used).
838
839 See the libev documentation at
840 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
841 _when_one_backend_> (locally installed as EV::libev) for more details.
842
843 In short, this watcher is most useful on BSD systems without working
844 kqueue to still be able to handle a large number of sockets:
845
846 my $socket_loop;
847
848 # check wether we use SELECT or POLL _and_ KQUEUE is supported
849 if (
850 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
851 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
852 ) {
853 # use kqueue for sockets
854 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
855 }
856
857 # use the default loop otherwise
858 $socket_loop ||= EV::default_loop;
859
860 $w = EV::embed $otherloop[, $callback]
861 $w = EV::embed_ns $otherloop[, $callback]
862 $w = $loop->embed ($otherloop[, $callback])
863 $w = $loop->embed_ns ($otherloop[, $callback])
864 Call the callback when the embedded event loop ($otherloop) has any
865 I/O activity. The $callback is optional: if it is missing, then the
866 embedded event loop will be managed automatically (which is
867 recommended), otherwise you have to invoke "sweep" yourself.
868
869 The "embed_ns" variant doesn't start (activate) the newly created
870 watcher.
871
872 ASYNC WATCHERS - how to wake up another event loop
873 Async watchers are provided by EV, but have little use in perl directly,
874 as perl neither supports threads running in parallel nor direct access
875 to signal handlers or other contexts where they could be of value.
876
877 It is, however, possible to use them from the XS level.
878
879 Please see the libev documentation for further details.
880
881 $w = EV::async $callback
882 $w = EV::async_ns $callback
883 $w->send
884 $bool = $w->async_pending
885
886PERL SIGNALS
887 While Perl signal handling (%SIG) is not affected by EV, the behaviour
888 with EV is as the same as any other C library: Perl-signals will only be
889 handled when Perl runs, which means your signal handler might be invoked
890 only the next time an event callback is invoked.
891
892 The solution is to use EV signal watchers (see "EV::signal"), which will
893 ensure proper operations with regards to other event watchers.
894
895 If you cannot do this for whatever reason, you can also force a watcher
896 to be called on every event loop iteration by installing a "EV::check"
897 watcher:
898
899 my $async_check = EV::check sub { };
900
901 This ensures that perl gets into control for a short time to handle any
902 pending signals, and also ensures (slightly) slower overall operation.
903
616THREADS 904ITHREADS
617 Threads are not supported by this module in any way. Perl pseudo-threads 905 Ithreads are not supported by this module in any way. Perl
618 is evil stuff and must die. As soon as Perl gains real threads I will 906 pseudo-threads is evil stuff and must die. Real threads as provided by
619 work on thread support for it. 907 Coro are fully supported (and enhanced support is available via
908 Coro::EV).
620 909
621FORK 910FORK
622 Most of the "improved" event delivering mechanisms of modern operating 911 Most of the "improved" event delivering mechanisms of modern operating
623 systems have quite a few problems with fork(2) (to put it bluntly: it is 912 systems have quite a few problems with fork(2) (to put it bluntly: it is
624 not supported and usually destructive). Libev makes it possible to work 913 not supported and usually destructive). Libev makes it possible to work
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634 923
635 On win32, there is no notion of fork so all this doesn't apply, of 924 On win32, there is no notion of fork so all this doesn't apply, of
636 course. 925 course.
637 926
638SEE ALSO 927SEE ALSO
639 EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event 928 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
640 loop), Coro::EV (efficient coroutines with EV). 929 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
930 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
931 agnostic and portable event driven programming.
641 932
642AUTHOR 933AUTHOR
643 Marc Lehmann <schmorp@schmorp.de> 934 Marc Lehmann <schmorp@schmorp.de>
644 http://home.schmorp.de/ 935 http://home.schmorp.de/
645 936

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