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Revision 1.26 by root, Wed May 21 23:40:08 2008 UTC

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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, 1, sub { 14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 1)"; 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
24 # IO 23
25 24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub { 26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks get the watcher object and event mask 27 my ($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
37 my $w = EV::signal 3, sub {
38 warn "sigquit received (this is GNU/Linux, right?)\n";
39 }; 36
40
41 # CHILD/PID STATUS CHANGES 37 # CHILD/PID STATUS CHANGES
42 38
43 my $w = EV::child 666, sub { 39 my $w = EV::child 666, 0, sub {
44 my ($w, $revents) = @_; 40 my ($w, $revents) = @_;
45 # my $pid = $w->rpid;
46 my $status = $w->rstatus; 41 my $status = $w->rstatus;
47 }; 42 };
48 43
44 # STAT CHANGES
45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_;
47 warn $w->path, " has changed somehow.\n";
48 };
49
49 # MAINLOOP 50 # MAINLOOP
50 EV::loop; # loop until EV::loop_done is called 51 EV::loop; # loop until EV::unloop is called or all watchers stop
51 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
52 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
53 54
54DESCRIPTION 55DESCRIPTION
55 This module provides an interface to libev 56 This module provides an interface to libev
56 (<http://software.schmorp.de/pkg/libev.html>). 57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
58 below is comprehensive, one might also consult the documentation of
59 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>)
60 for more subtle details on watcher semantics or some discussion on the
61 available backends, or how to force a specific backend with
62 "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
71EVENT LOOPS
72 EV supports multiple event loops: There is a single "default event loop"
73 that can handle everything including signals and child watchers, and any
74 number of "dynamic event loops" that can use different backends (with
75 various limitations), but no child and signal watchers.
76
77 You do not have to do anything to create the default event loop: When
78 the module is loaded a suitable backend is selected on the premise of
79 selecting a working backend (which for example rules out kqueue on most
80 BSDs). Modules should, unless they have "special needs" always use the
81 default loop as this is fastest (perl-wise), best supported by other
82 modules (e.g. AnyEvent or Coro) and most portable event loop.
83
84 For specific programs you can create additional event loops dynamically.
85
86 $loop = new EV::loop [$flags]
87 Create a new event loop as per the specified flags. Please refer to
88 the "ev_loop_new ()" function description in the libev documentation
89 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
90 ONS>) for more info.
91
92 The loop will automatically be destroyed when it is no longer
93 referenced by any watcher and the loop object goes out of scope.
94
95 Using "EV::FLAG_FORKCHECK" is recommended, as only the default event
96 loop is protected by this module.
97
98 $loop->loop_fork
99 Must be called after a fork in the child, before entering or
100 continuing the event loop. An alternative is to use
101 "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at
102 some performance loss (refer to the libev documentation).
103
104 $loop = EV::default_loop [$flags]
105 Return the default loop (which is a singleton object).
57 106
58BASIC INTERFACE 107BASIC INTERFACE
59 $EV::DIED 108 $EV::DIED
60 Must contain a reference to a function that is called when a 109 Must contain a reference to a function that is called when a
61 callback throws an exception (with $@ containing thr error). The 110 callback throws an exception (with $@ containing the error). The
62 default prints an informative message and continues. 111 default prints an informative message and continues.
63 112
64 If this callback throws an exception it will be silently ignored. 113 If this callback throws an exception it will be silently ignored.
114
115 $flags = EV::supported_backends
116 $flags = EV::recommended_backends
117 $flags = EV::embeddable_backends
118 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
119 this instance of EV, the set of recommended backends (supposed to be
120 good) for this platform and the set of embeddable backends (see
121 EMBED WATCHERS).
122
123 EV::sleep $seconds
124 Block the process for the given number of (fractional) seconds.
65 125
66 $time = EV::time 126 $time = EV::time
67 Returns the current time in (fractional) seconds since the epoch. 127 Returns the current time in (fractional) seconds since the epoch.
68 128
69 $time = EV::now 129 $time = EV::now
130 $time = $loop->now
70 Returns the time the last event loop iteration has been started. 131 Returns the time the last event loop iteration has been started.
71 This is the time that (relative) timers are based on, and refering 132 This is the time that (relative) timers are based on, and refering
72 to it is usually faster then calling EV::time. 133 to it is usually faster then calling EV::time.
73 134
74 $method = EV::ev_method 135 $backend = EV::backend
136 $backend = $loop->backend
75 Returns an integer describing the backend used by libev 137 Returns an integer describing the backend used by libev
76 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 138 (EV::METHOD_SELECT or EV::METHOD_EPOLL).
77 139
78 EV::loop [$flags] 140 EV::loop [$flags]
141 $loop->loop ([$flags])
79 Begin checking for events and calling callbacks. It returns when a 142 Begin checking for events and calling callbacks. It returns when a
80 callback calls EV::loop_done. 143 callback calls EV::unloop.
81 144
82 The $flags argument can be one of the following: 145 The $flags argument can be one of the following:
83 146
84 0 as above 147 0 as above
85 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 148 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
86 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 149 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
87 150
88 EV::loop_done [$how] 151 EV::unloop [$how]
152 $loop->unloop ([$how])
89 When called with no arguments or an argument of 1, makes the 153 When called with no arguments or an argument of EV::UNLOOP_ONE,
90 innermost call to EV::loop return. 154 makes the innermost call to EV::loop return.
91 155
92 When called with an agrument of 2, all calls to EV::loop will return 156 When called with an argument of EV::UNLOOP_ALL, all calls to
93 as fast as possible. 157 EV::loop will return as fast as possible.
94 158
95 WATCHER 159 $count = EV::loop_count
160 $count = $loop->loop_count
161 Return the number of times the event loop has polled for new events.
162 Sometiems useful as a generation counter.
163
164 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
165 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
166 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.
168
169 If $fh_or_undef is a filehandle or file descriptor, then $events
170 must be a bitset containing either "EV::READ", "EV::WRITE" or
171 "EV::READ | EV::WRITE", indicating the type of I/O event you want to
172 wait for. If you do not want to wait for some I/O event, specify
173 "undef" for $fh_or_undef and 0 for $events).
174
175 If timeout is "undef" or negative, then there will be no timeout.
176 Otherwise a EV::timer with this value will be started.
177
178 When an error occurs or either the timeout or I/O watcher triggers,
179 then the callback will be called with the received event set (in
180 general you can expect it to be a combination of "EV::ERROR",
181 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
182
183 EV::once doesn't return anything: the watchers stay active till
184 either of them triggers, then they will be stopped and freed, and
185 the callback invoked.
186
187 EV::feed_fd_event ($fd, $revents)
188 $loop->feed_fd_event ($fd, $revents)
189 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
191 combination of "EV::READ" and "EV::WRITE") happened on the file
192 descriptor $fd.
193
194 EV::feed_signal_event ($signal)
195 Feed a signal event into EV. EV will react to this call as if the
196 signal specified by $signal had occured.
197
198 EV::set_io_collect_interval $time
199 $loop->set_io_collect_interval ($time)
200 EV::set_timeout_collect_interval $time
201 $loop->set_timeout_collect_interval ($time)
202 These advanced functions set the minimum block interval when polling
203 for I/O events and the minimum wait interval for timer events. See
204 the libev documentation at
205 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
206 ROLLING_THE_EVENT_LOOP> for a more detailed discussion.
207
208WATCHER OBJECTS
96 A watcher is an object that gets created to record your interest in some 209 A watcher is an object that gets created to record your interest in some
97 event. For instance, if you want to wait for STDIN to become readable, 210 event. For instance, if you want to wait for STDIN to become readable,
98 you would create an EV::io watcher for that: 211 you would create an EV::io watcher for that:
99 212
100 my $watcher = EV::io *STDIN, EV::READ, sub { 213 my $watcher = EV::io *STDIN, EV::READ, sub {
101 my ($watcher, $revents) = @_; 214 my ($watcher, $revents) = @_;
102 warn "yeah, STDIN should not be readable without blocking!\n" 215 warn "yeah, STDIN should now be readable without blocking!\n"
103 }; 216 };
104 217
105 All watchers can be active (waiting for events) or inactive (paused). 218 All watchers can be active (waiting for events) or inactive (paused).
106 Only active watchers will have their callbacks invoked. All callbacks 219 Only active watchers will have their callbacks invoked. All callbacks
107 will be called with at least two arguments: the watcher and a bitmask of 220 will be called with at least two arguments: the watcher and a bitmask of
108 received events. 221 received events.
109 222
110 Each watcher type has its associated bit in revents, so you can use the 223 Each watcher type has its associated bit in revents, so you can use the
111 same callback for multiple watchers. The event mask is named after the 224 same callback for multiple watchers. The event mask is named after the
112 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 225 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
113 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 226 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
114 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 227 events (which can set both EV::READ and EV::WRITE bits), and EV::timer
115 (which uses EV::TIMEOUT). 228 (which uses EV::TIMEOUT).
116 229
117 In the rare case where one wants to create a watcher but not start it at 230 In the rare case where one wants to create a watcher but not start it at
118 the same time, each constructor has a variant with a trailing "_ns" in 231 the same time, each constructor has a variant with a trailing "_ns" in
… …
124 237
125 Also, all methods changing some aspect of a watcher (->set, ->priority, 238 Also, all methods changing some aspect of a watcher (->set, ->priority,
126 ->fh and so on) automatically stop and start it again if it is active, 239 ->fh and so on) automatically stop and start it again if it is active,
127 which means pending events get lost. 240 which means pending events get lost.
128 241
129 WATCHER TYPES 242 COMMON WATCHER METHODS
130 Now lets move to the existing watcher types and asociated methods. 243 This section lists methods common to all watchers.
131
132 The following methods are available for all watchers. Then followes a
133 description of each watcher constructor (EV::io, EV::timer,
134 EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and
135 EV::check), followed by any type-specific methods (if any).
136 244
137 $w->start 245 $w->start
138 Starts a watcher if it isn't active already. Does nothing to an 246 Starts a watcher if it isn't active already. Does nothing to an
139 already active watcher. By default, all watchers start out in the 247 already active watcher. By default, all watchers start out in the
140 active state (see the description of the "_ns" variants if you need 248 active state (see the description of the "_ns" variants if you need
141 stopped watchers). 249 stopped watchers).
142 250
143 $w->stop 251 $w->stop
144 Stop a watcher if it is active. Also clear any pending events 252 Stop a watcher if it is active. Also clear any pending events
145 (events that have been received but that didn't yet result in a 253 (events that have been received but that didn't yet result in a
146 callback invocation), regardless of wether the watcher was active or 254 callback invocation), regardless of whether the watcher was active
147 not. 255 or not.
148 256
149 $bool = $w->is_active 257 $bool = $w->is_active
150 Returns true if the watcher is active, false otherwise. 258 Returns true if the watcher is active, false otherwise.
151 259
152 $current_data = $w->data 260 $current_data = $w->data
… …
170 Pending watchers with higher priority will be invoked first. The 278 Pending watchers with higher priority will be invoked first. The
171 valid range of priorities lies between EV::MAXPRI (default 2) and 279 valid range of priorities lies between EV::MAXPRI (default 2) and
172 EV::MINPRI (default -2). If the priority is outside this range it 280 EV::MINPRI (default -2). If the priority is outside this range it
173 will automatically be normalised to the nearest valid priority. 281 will automatically be normalised to the nearest valid priority.
174 282
175 The default priority of any newly-created weatcher is 0. 283 The default priority of any newly-created watcher is 0.
176 284
285 Note that the priority semantics have not yet been fleshed out and
286 are subject to almost certain change.
287
177 $w->trigger ($revents) 288 $w->invoke ($revents)
178 Call the callback *now* with the given event mask. 289 Call the callback *now* with the given event mask.
179 290
291 $w->feed_event ($revents)
292 Feed some events on this watcher into EV. EV will react to this call
293 as if the watcher had received the given $revents mask.
294
295 $revents = $w->clear_pending
296 If the watcher is pending, this function clears its pending status
297 and returns its $revents bitset (as if its callback was invoked). If
298 the watcher isn't pending it does nothing and returns 0.
299
300 $previous_state = $w->keepalive ($bool)
301 Normally, "EV::loop" will return when there are no active watchers
302 (which is a "deadlock" because no progress can be made anymore).
303 This is convinient because it allows you to start your watchers (and
304 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
306 for their task :).
307
308 Sometimes, however, this gets in your way, for example when the
309 module that calls "EV::loop" (usually the main program) is not the
310 same module as a long-living watcher (for example a DNS client
311 module written by somebody else even). Then you might want any
312 outstanding requests to be handled, but you would not want to keep
313 "EV::loop" from returning just because you happen to have this
314 long-running UDP port watcher.
315
316 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
318 returning.
319
320 The initial value for keepalive is true (enabled), and you cna
321 change it any time.
322
323 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.
325
326 my $udp_socket = ...
327 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
328 $1000udp_watcher->keepalive (0);
329
330 $loop = $w->loop
331 Return the loop that this watcher is attached to.
332
333WATCHER TYPES
334 Each of the following subsections describes a single watcher type.
335
336 I/O WATCHERS - is this file descriptor readable or writable?
180 $w = EV::io $fileno_or_fh, $eventmask, $callback 337 $w = EV::io $fileno_or_fh, $eventmask, $callback
181 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 338 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
339 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
340 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
182 As long as the returned watcher object is alive, call the $callback 341 As long as the returned watcher object is alive, call the $callback
183 when the events specified in $eventmask. 342 when at least one of events specified in $eventmask occurs.
184 343
185 The $eventmask can be one or more of these constants ORed together: 344 The $eventmask can be one or more of these constants ORed together:
186 345
187 EV::READ wait until read() wouldn't block anymore 346 EV::READ wait until read() wouldn't block anymore
188 EV::WRITE wait until write() wouldn't block anymore 347 EV::WRITE wait until write() wouldn't block anymore
… …
200 359
201 $current_eventmask = $w->events 360 $current_eventmask = $w->events
202 $old_eventmask = $w->events ($new_eventmask) 361 $old_eventmask = $w->events ($new_eventmask)
203 Returns the previously set event mask and optionally set a new one. 362 Returns the previously set event mask and optionally set a new one.
204 363
364 TIMER WATCHERS - relative and optionally repeating timeouts
205 $w = EV::timer $after, $repeat, $callback 365 $w = EV::timer $after, $repeat, $callback
206 $w = EV::timer_ns $after, $repeat, $callback 366 $w = EV::timer_ns $after, $repeat, $callback
207 Calls the callback after $after seconds. If $repeat is non-zero, the 367 $w = $loop->timer ($after, $repeat, $callback)
208 timer will be restarted (with the $repeat value as $after) after the 368 $w = $loop->timer_ns ($after, $repeat, $callback)
209 callback returns. 369 Calls the callback after $after seconds (which may be fractional).
370 If $repeat is non-zero, the timer will be restarted (with the
371 $repeat value as $after) after the callback returns.
210 372
211 This means that the callback would be called roughly after $after 373 This means that the callback would be called roughly after $after
212 seconds, and then every $repeat seconds. "Roughly" because the time 374 seconds, and then every $repeat seconds. The timer does his best not
213 of callback processing is not taken into account, so the timer will 375 to drift, but it will not invoke the timer more often then once per
214 slowly drift. If that isn't acceptable, look at EV::periodic. 376 event loop iteration, and might drift in other cases. If that isn't
377 acceptable, look at EV::periodic, which can provide long-term stable
378 timers.
215 379
216 The timer is based on a monotonic clock, that is if somebody is 380 The timer is based on a monotonic clock, that is, if somebody is
217 sitting in front of the machine while the timer is running and 381 sitting in front of the machine while the timer is running and
218 changes the system clock, the timer will nevertheless run (roughly) 382 changes the system clock, the timer will nevertheless run (roughly)
219 the same time. 383 the same time.
220 384
221 The "timer_ns" variant doesn't start (activate) the newly created 385 The "timer_ns" variant doesn't start (activate) the newly created
222 watcher. 386 watcher.
223 387
224 $w->set ($after, $repeat) 388 $w->set ($after, $repeat)
225 Reconfigures the watcher, see the constructor above for details. Can 389 Reconfigures the watcher, see the constructor above for details. Can
226 be at any time. 390 be called at any time.
227 391
228 $w->again 392 $w->again
229 Similar to the "start" method, but has special semantics for 393 Similar to the "start" method, but has special semantics for
230 repeating timers: 394 repeating timers:
231 395
396 If the timer is active and non-repeating, it will be stopped.
397
232 If the timer is active and repeating, reset the timeout to occur 398 If the timer is active and repeating, reset the timeout to occur
233 $repeat seconds after now. 399 $repeat seconds after now.
234 400
235 If the timer is active and non-repeating, it will be stopped.
236
237 If the timer is in active and repeating, start it. 401 If the timer is inactive and repeating, start it using the repeat
402 value.
238 403
239 Otherwise do nothing. 404 Otherwise do nothing.
240 405
241 This behaviour is useful when you have a timeout for some IO 406 This behaviour is useful when you have a timeout for some IO
242 operation. You create a timer object with the same value for $after 407 operation. You create a timer object with the same value for $after
243 and $repeat, and then, in the read/write watcher, run the "again" 408 and $repeat, and then, in the read/write watcher, run the "again"
244 method on the timeout. 409 method on the timeout.
245 410
411 PERIODIC WATCHERS - to cron or not to cron?
246 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 412 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
247 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 413 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
414 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
415 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
248 Similar to EV::timer, but is not based on relative timeouts but on 416 Similar to EV::timer, but is not based on relative timeouts but on
249 absolute times. Apart from creating "simple" timers that trigger 417 absolute times. Apart from creating "simple" timers that trigger
250 "at" the specified time, it can also be used for non-drifting 418 "at" the specified time, it can also be used for non-drifting
251 absolute timers and more complex, cron-like, setups that are not 419 absolute timers and more complex, cron-like, setups that are not
252 adversely affected by time jumps (i.e. when the system clock is 420 adversely affected by time jumps (i.e. when the system clock is
253 changed by explicit date -s or other means such as ntpd). It is also 421 changed by explicit date -s or other means such as ntpd). It is also
254 the most complex watcher type in EV. 422 the most complex watcher type in EV.
255 423
256 It has three distinct "modes": 424 It has three distinct "modes":
257 425
258 * absolute timer ($interval = $reschedule_cb = 0) 426 * absolute timer ($interval = $reschedule_cb = 0)
427
259 This time simply fires at the wallclock time $at and doesn't 428 This time simply fires at the wallclock time $at and doesn't
260 repeat. It will not adjust when a time jump occurs, that is, if 429 repeat. It will not adjust when a time jump occurs, that is, if
261 it is to be run at January 1st 2011 then it will run when the 430 it is to be run at January 1st 2011 then it will run when the
262 system time reaches or surpasses this time. 431 system time reaches or surpasses this time.
263 432
264 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 433 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
434
265 In this mode the watcher will always be scheduled to time out at 435 In this mode the watcher will always be scheduled to time out at
266 the next "$at + N * $interval" time (for some integer N) and 436 the next "$at + N * $interval" time (for some integer N) and
267 then repeat, regardless of any time jumps. 437 then repeat, regardless of any time jumps.
268 438
269 This can be used to create timers that do not drift with respect 439 This can be used to create timers that do not drift with respect
… …
278 Another way to think about it (for the mathematically inclined) 448 Another way to think about it (for the mathematically inclined)
279 is that EV::periodic will try to run the callback in this mode 449 is that EV::periodic will try to run the callback in this mode
280 at the next possible time where "$time = $at (mod $interval)", 450 at the next possible time where "$time = $at (mod $interval)",
281 regardless of any time jumps. 451 regardless of any time jumps.
282 452
283 * manual reschedule mode ($reschedule_cb = coderef) 453 * manual reschedule mode ($reschedule_cb = coderef)
454
284 In this mode $interval and $at are both being ignored. Instead, 455 In this mode $interval and $at are both being ignored. Instead,
285 each time the periodic watcher gets scheduled, the first 456 each time the periodic watcher gets scheduled, the reschedule
286 callback ($reschedule_cb) will be called with the watcher as 457 callback ($reschedule_cb) will be called with the watcher as
287 first, and the current time as second argument. 458 first, and the current time as second argument.
288 459
289 *This callback MUST NOT stop or destroy this or any other 460 *This callback MUST NOT stop or destroy this or any other
461 periodic watcher, ever, and MUST NOT call any event loop
290 periodic watcher, ever*. If you need to stop it, return 1e30 and 462 functions or methods*. If you need to stop it, return 1e30 and
291 stop it afterwards. 463 stop it afterwards. You may create and start a "EV::prepare"
464 watcher for this task.
292 465
293 It must return the next time to trigger, based on the passed 466 It must return the next time to trigger, based on the passed
294 time value (that is, the lowest time value larger than to the 467 time value (that is, the lowest time value larger than or equal
295 second argument). It will usually be called just before the 468 to to the second argument). It will usually be called just
296 callback will be triggered, but might be called at other times, 469 before the callback will be triggered, but might be called at
297 too. 470 other times, too.
298 471
299 This can be used to create very complex timers, such as a timer 472 This can be used to create very complex timers, such as a timer
300 that triggers on each midnight, local time (actually 24 hours 473 that triggers on each midnight, local time (actually 24 hours
301 after the last midnight, to keep the example simple. If you know 474 after the last midnight, to keep the example simple. If you know
302 a way to do it correctly in about the same space (without 475 a way to do it correctly in about the same space (without
… …
315 The "periodic_ns" variant doesn't start (activate) the newly created 488 The "periodic_ns" variant doesn't start (activate) the newly created
316 watcher. 489 watcher.
317 490
318 $w->set ($at, $interval, $reschedule_cb) 491 $w->set ($at, $interval, $reschedule_cb)
319 Reconfigures the watcher, see the constructor above for details. Can 492 Reconfigures the watcher, see the constructor above for details. Can
320 be at any time. 493 be called at any time.
321 494
322 $w->again 495 $w->again
323 Simply stops and starts the watcher again. 496 Simply stops and starts the watcher again.
324 497
498 $time = $w->at
499 Return the time that the watcher is expected to trigger next.
500
501 SIGNAL WATCHERS - signal me when a signal gets signalled!
325 $w = EV::signal $signal, $callback 502 $w = EV::signal $signal, $callback
326 $w = EV::signal_ns $signal, $callback 503 $w = EV::signal_ns $signal, $callback
327 Call the callback when $signal is received (the signal can be 504 Call the callback when $signal is received (the signal can be
328 specified by number or by name, just as with kill or %SIG). 505 specified by number or by name, just as with "kill" or %SIG).
329 506
330 EV will grab the signal for the process (the kernel only allows one 507 EV will grab the signal for the process (the kernel only allows one
331 component to receive a signal at a time) when you start a signal 508 component to receive a signal at a time) when you start a signal
332 watcher, and removes it again when you stop it. Perl does the same 509 watcher, and removes it again when you stop it. Perl does the same
333 when you add/remove callbacks to %SIG, so watch out. 510 when you add/remove callbacks to %SIG, so watch out.
… …
337 The "signal_ns" variant doesn't start (activate) the newly created 514 The "signal_ns" variant doesn't start (activate) the newly created
338 watcher. 515 watcher.
339 516
340 $w->set ($signal) 517 $w->set ($signal)
341 Reconfigures the watcher, see the constructor above for details. Can 518 Reconfigures the watcher, see the constructor above for details. Can
342 be at any time. 519 be called at any time.
343 520
344 $current_signum = $w->signal 521 $current_signum = $w->signal
345 $old_signum = $w->signal ($new_signal) 522 $old_signum = $w->signal ($new_signal)
346 Returns the previously set signal (always as a number not name) and 523 Returns the previously set signal (always as a number not name) and
347 optionally set a new one. 524 optionally set a new one.
348 525
526 CHILD WATCHERS - watch out for process status changes
349 $w = EV::child $pid, $callback 527 $w = EV::child $pid, $trace, $callback
350 $w = EV::child_ns $pid, $callback 528 $w = EV::child_ns $pid, $trace, $callback
529 $w = $loop->child ($pid, $trace, $callback)
530 $w = $loop->child_ns ($pid, $trace, $callback)
351 Call the callback when a status change for pid $pid (or any pid if 531 Call the callback when a status change for pid $pid (or any pid if
352 $pid is 0) has been received. More precisely: when the process 532 $pid is 0) has been received (a status change happens when the
533 process terminates or is killed, or, when trace is true,
534 additionally when it is stopped or continued). More precisely: when
353 receives a SIGCHLD, EV will fetch the outstanding exit/wait status 535 the process receives a "SIGCHLD", EV will fetch the outstanding
354 for all changed/zombie children and call the callback. 536 exit/wait status for all changed/zombie children and call the
537 callback.
355 538
356 You can access both status and pid by using the "rstatus" and "rpid" 539 It is valid (and fully supported) to install a child watcher after a
540 child has exited but before the event loop has started its next
541 iteration (for example, first you "fork", then the new child process
542 might exit, and only then do you install a child watcher in the
543 parent for the new pid).
544
545 You can access both exit (or tracing) status and pid by using the
357 methods on the watcher object. 546 "rstatus" and "rpid" methods on the watcher object.
358 547
359 You can have as many pid watchers per pid as you want. 548 You can have as many pid watchers per pid as you want, they will all
549 be called.
360 550
361 The "child_ns" variant doesn't start (activate) the newly created 551 The "child_ns" variant doesn't start (activate) the newly created
362 watcher. 552 watcher.
363 553
364 $w->set ($pid) 554 $w->set ($pid, $trace)
365 Reconfigures the watcher, see the constructor above for details. Can 555 Reconfigures the watcher, see the constructor above for details. Can
366 be at any time. 556 be called at any time.
367 557
368 $current_pid = $w->pid 558 $current_pid = $w->pid
369 $old_pid = $w->pid ($new_pid)
370 Returns the previously set process id and optionally set a new one. 559 Returns the previously set process id and optionally set a new one.
371 560
372 $exit_status = $w->rstatus 561 $exit_status = $w->rstatus
373 Return the exit/wait status (as returned by waitpid, see the waitpid 562 Return the exit/wait status (as returned by waitpid, see the waitpid
374 entry in perlfunc). 563 entry in perlfunc).
375 564
376 $pid = $w->rpid 565 $pid = $w->rpid
377 Return the pid of the awaited child (useful when you have installed 566 Return the pid of the awaited child (useful when you have installed
378 a watcher for all pids). 567 a watcher for all pids).
379 568
569 STAT WATCHERS - did the file attributes just change?
570 $w = EV::stat $path, $interval, $callback
571 $w = EV::stat_ns $path, $interval, $callback
572 $w = $loop->stat ($path, $interval, $callback)
573 $w = $loop->stat_ns ($path, $interval, $callback)
574 Call the callback when a file status change has been detected on
575 $path. The $path does not need to exist, changing from "path exists"
576 to "path does not exist" is a status change like any other.
577
578 The $interval is a recommended polling interval for systems where
579 OS-supported change notifications don't exist or are not supported.
580 If you use 0 then an unspecified default is used (which is highly
581 recommended!), which is to be expected to be around five seconds
582 usually.
583
584 This watcher type is not meant for massive numbers of stat watchers,
585 as even with OS-supported change notifications, this can be
586 resource-intensive.
587
588 The "stat_ns" variant doesn't start (activate) the newly created
589 watcher.
590
591 ... = $w->stat
592 This call is very similar to the perl "stat" built-in: It stats
593 (using "lstat") the path specified in the watcher and sets perls
594 stat cache (as well as EV's idea of the current stat values) to the
595 values found.
596
597 In scalar context, a boolean is return indicating success or failure
598 of the stat. In list context, the same 13-value list as with stat is
599 returned (except that the blksize and blocks fields are not
600 reliable).
601
602 In the case of an error, errno is set to "ENOENT" (regardless of the
603 actual error value) and the "nlink" value is forced to zero (if the
604 stat was successful then nlink is guaranteed to be non-zero).
605
606 See also the next two entries for more info.
607
608 ... = $w->attr
609 Just like "$w->stat", but without the initial stat'ing: this returns
610 the values most recently detected by EV. See the next entry for more
611 info.
612
613 ... = $w->prev
614 Just like "$w->stat", but without the initial stat'ing: this returns
615 the previous set of values, before the change.
616
617 That is, when the watcher callback is invoked, "$w->prev" will be
618 set to the values found *before* a change was detected, while
619 "$w->attr" returns the values found leading to the change detection.
620 The difference (if any) between "prev" and "attr" is what triggered
621 the callback.
622
623 If you did something to the filesystem object and do not want to
624 trigger yet another change, you can call "stat" to update EV's idea
625 of what the current attributes are.
626
627 $w->set ($path, $interval)
628 Reconfigures the watcher, see the constructor above for details. Can
629 be called at any time.
630
631 $current_path = $w->path
632 $old_path = $w->path ($new_path)
633 Returns the previously set path and optionally set a new one.
634
635 $current_interval = $w->interval
636 $old_interval = $w->interval ($new_interval)
637 Returns the previously set interval and optionally set a new one.
638 Can be used to query the actual interval used.
639
640 IDLE WATCHERS - when you've got nothing better to do...
380 $w = EV::idle $callback 641 $w = EV::idle $callback
381 $w = EV::idle_ns $callback 642 $w = EV::idle_ns $callback
643 $w = $loop->idle ($callback)
644 $w = $loop->idle_ns ($callback)
382 Call the callback when there are no pending io, timer/periodic, 645 Call the callback when there are no other pending watchers of the
383 signal or child events, i.e. when the process is idle. 646 same or higher priority (excluding check, prepare and other idle
647 watchers of the same or lower priority, of course). They are called
648 idle watchers because when the watcher is the highest priority
649 pending event in the process, the process is considered to be idle
650 at that priority.
651
652 If you want a watcher that is only ever called when *no* other
653 events are outstanding you have to set the priority to "EV::MINPRI".
384 654
385 The process will not block as long as any idle watchers are active, 655 The process will not block as long as any idle watchers are active,
386 and they will be called repeatedly until stopped. 656 and they will be called repeatedly until stopped.
387 657
658 For example, if you have idle watchers at priority 0 and 1, and an
659 I/O watcher at priority 0, then the idle watcher at priority 1 and
660 the I/O watcher will always run when ready. Only when the idle
661 watcher at priority 1 is stopped and the I/O watcher at priority 0
662 is not pending with the 0-priority idle watcher be invoked.
663
388 The "idle_ns" variant doesn't start (activate) the newly created 664 The "idle_ns" variant doesn't start (activate) the newly created
389 watcher. 665 watcher.
390 666
667 PREPARE WATCHERS - customise your event loop!
391 $w = EV::prepare $callback 668 $w = EV::prepare $callback
392 $w = EV::prepare_ns $callback 669 $w = EV::prepare_ns $callback
670 $w = $loop->prepare ($callback)
671 $w = $loop->prepare_ns ($callback)
393 Call the callback just before the process would block. You can still 672 Call the callback just before the process would block. You can still
394 create/modify any watchers at this point. 673 create/modify any watchers at this point.
395 674
396 See the EV::check watcher, below, for explanations and an example. 675 See the EV::check watcher, below, for explanations and an example.
397 676
398 The "prepare_ns" variant doesn't start (activate) the newly created 677 The "prepare_ns" variant doesn't start (activate) the newly created
399 watcher. 678 watcher.
400 679
680 CHECK WATCHERS - customise your event loop even more!
401 $w = EV::check $callback 681 $w = EV::check $callback
402 $w = EV::check_ns $callback 682 $w = EV::check_ns $callback
683 $w = $loop->check ($callback)
684 $w = $loop->check_ns ($callback)
403 Call the callback just after the process wakes up again (after it 685 Call the callback just after the process wakes up again (after it
404 has gathered events), but before any other callbacks have been 686 has gathered events), but before any other callbacks have been
405 invoked. 687 invoked.
406 688
407 This is used to integrate other event-based software into the EV 689 This is used to integrate other event-based software into the EV
… …
416 # do nothing unless active 698 # do nothing unless active
417 $dispatcher->{_event_queue_h} 699 $dispatcher->{_event_queue_h}
418 or return; 700 or return;
419 701
420 # make the dispatcher handle any outstanding stuff 702 # make the dispatcher handle any outstanding stuff
703 ... not shown
421 704
422 # create an IO watcher for each and every socket 705 # create an I/O watcher for each and every socket
423 @snmp_watcher = ( 706 @snmp_watcher = (
424 (map { EV::io $_, EV::READ, sub { } } 707 (map { EV::io $_, EV::READ, sub { } }
425 keys %{ $dispatcher->{_descriptors} }), 708 keys %{ $dispatcher->{_descriptors} }),
709
710 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
711 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
712 0, sub { },
426 ); 713 );
427
428 # if there are any timeouts, also create a timer
429 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
430 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
431 }; 714 };
432 715
433 The callbacks are irrelevant, the only purpose of those watchers is 716 The callbacks are irrelevant (and are not even being called), the
434 to wake up the process as soon as one of those events occurs (socket 717 only purpose of those watchers is to wake up the process as soon as
435 readable, or timer timed out). The corresponding EV::check watcher 718 one of those events occurs (socket readable, or timer timed out).
436 will then clean up: 719 The corresponding EV::check watcher will then clean up:
437 720
438 our $snmp_check = EV::check sub { 721 our $snmp_check = EV::check sub {
439 # destroy all watchers 722 # destroy all watchers
440 @snmp_watcher = (); 723 @snmp_watcher = ();
441 724
442 # make the dispatcher handle any new stuff 725 # make the dispatcher handle any new stuff
726 ... not shown
443 }; 727 };
444 728
445 The callbacks of the created watchers will not be called as the 729 The callbacks of the created watchers will not be called as the
446 watchers are destroyed before this cna happen (remember EV::check 730 watchers are destroyed before this cna happen (remember EV::check
447 gets called first). 731 gets called first).
448 732
449 The "check_ns" variant doesn't start (activate) the newly created 733 The "check_ns" variant doesn't start (activate) the newly created
450 watcher. 734 watcher.
451 735
736 FORK WATCHERS - the audacity to resume the event loop after a fork
737 Fork watchers are called when a "fork ()" was detected. The invocation
738 is done before the event loop blocks next and before "check" watchers
739 are being called, and only in the child after the fork.
740
741 $w = EV::fork $callback
742 $w = EV::fork_ns $callback
743 $w = $loop->fork ($callback)
744 $w = $loop->fork_ns ($callback)
745 Call the callback before the event loop is resumed in the child
746 process after a fork.
747
748 The "fork_ns" variant doesn't start (activate) the newly created
749 watcher.
750
751 EMBED WATCHERS - when one backend isn't enough...
752 This is a rather advanced watcher type that lets you embed one event
753 loop into another (currently only IO events are supported in the
754 embedded loop, other types of watchers might be handled in a delayed or
755 incorrect fashion and must not be used).
756
757 See the libev documentation at
758 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
759 _when_one_backend_> for more details.
760
761 In short, this watcher is most useful on BSD systems without working
762 kqueue to still be able to handle a large number of sockets:
763
764 my $socket_loop;
765
766 # check wether we use SELECT or POLL _and_ KQUEUE is supported
767 if (
768 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
769 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
770 ) {
771 # use kqueue for sockets
772 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
773 }
774
775 # use the default loop otherwise
776 $socket_loop ||= EV::default_loop;
777
778 $w = EV::embed $otherloop, $callback
779 $w = EV::embed_ns $otherloop, $callback
780 $w = $loop->embed ($otherloop, $callback)
781 $w = $loop->embed_ns ($otherloop, $callback)
782 Call the callback when the embedded event loop ($otherloop) has any
783 I/O activity. The $callback should alwas be specified as "undef" in
784 this version of EV, which means the embedded event loop will be
785 managed automatically.
786
787 The "embed_ns" variant doesn't start (activate) the newly created
788 watcher.
789
790 ASYNC WATCHERS - how to wake up another event loop
791 Async watchers are provided by EV, but have little use in perl directly,
792 as perl neither supports threads nor direct access to signal handlers or
793 other contexts where they could be of value.
794
795 It is, however, possible to use them from the XS level.
796
797 Please see the libev documentation for further details.
798
799 $w = EV::async $callback
800 $w = EV::async_ns $callback
801 $w->send
802 $bool = $w->async_pending
803
804PERL SIGNALS
805 While Perl signal handling (%SIG) is not affected by EV, the behaviour
806 with EV is as the same as any other C library: Perl-signals will only be
807 handled when Perl runs, which means your signal handler might be invoked
808 only the next time an event callback is invoked.
809
810 The solution is to use EV signal watchers (see "EV::signal"), which will
811 ensure proper operations with regards to other event watchers.
812
813 If you cannot do this for whatever reason, you can also force a watcher
814 to be called on every event loop iteration by installing a "EV::check"
815 watcher:
816
817 my $async_check = EV::check sub { };
818
819 This ensures that perl gets into control for a short time to handle any
820 pending signals, and also ensures (slightly) slower overall operation.
821
452THREADS 822THREADS
453 Threads are not supported by this in any way. Perl pseudo-threads is 823 Threads are not supported by this module in any way. Perl pseudo-threads
454 evil stuff and must die. 824 is evil stuff and must die. As soon as Perl gains real threads I will
825 work on thread support for it.
826
827FORK
828 Most of the "improved" event delivering mechanisms of modern operating
829 systems have quite a few problems with fork(2) (to put it bluntly: it is
830 not supported and usually destructive). Libev makes it possible to work
831 around this by having a function that recreates the kernel state after
832 fork in the child.
833
834 On non-win32 platforms, this module requires the pthread_atfork
835 functionality to do this automatically for you. This function is quite
836 buggy on most BSDs, though, so YMMV. The overhead for this is quite
837 negligible, because everything the function currently does is set a flag
838 that is checked only when the event loop gets used the next time, so
839 when you do fork but not use EV, the overhead is minimal.
840
841 On win32, there is no notion of fork so all this doesn't apply, of
842 course.
455 843
456SEE ALSO 844SEE ALSO
457 L<EV::DNS>, L<EV::AnyEvent>. 845 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
846 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
847 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
848 agnostic and portable event driven programming.
458 849
459AUTHOR 850AUTHOR
460 Marc Lehmann <schmorp@schmorp.de> 851 Marc Lehmann <schmorp@schmorp.de>
461 http://home.schmorp.de/ 852 http://home.schmorp.de/
462 853

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