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Revision 1.31 by root, Wed Nov 19 10:33:32 2008 UTC

1NAME 1NAME
2 EV - perl interface to libev, a high performance full-featured event 2 EV - perl interface to libev, a high performance full-featured event
3 loop 3 loop
4 4
5SYNOPSIS 5SYNOPSIS
6 use EV; 6 use EV;
7 7
8 # TIMERS 8 # TIMERS
9 9
10 my $w = EV::timer 2, 0, sub { 10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s"; 11 warn "is called after 2s";
12 }; 12 };
13 13
14 my $w = EV::timer 2, 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 23
24 # IO 24 # IO
25 25
26 my $w = EV::io *STDIN, EV::READ, sub { 26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks get the watcher object and event mask 27 my ($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> or
60 perldoc EV::libev) for more subtle details on watcher semantics or some
61 discussion on the available backends, or how to force a specific backend
62 with "LIBEV_FLAGS", or just about in any case because it has much more
63 detailed information.
64
65 This module is very fast and scalable. It is actually so fast that you
66 can use it through the AnyEvent module, stay portable to other event
67 loops (if you don't rely on any watcher types not available through it)
68 and still be faster than with any other event loop currently supported
69 in Perl.
70
71 MODULE EXPORTS
72 This module does not export any symbols.
73
74EVENT LOOPS
75 EV supports multiple event loops: There is a single "default event loop"
76 that can handle everything including signals and child watchers, and any
77 number of "dynamic event loops" that can use different backends (with
78 various limitations), but no child and signal watchers.
79
80 You do not have to do anything to create the default event loop: When
81 the module is loaded a suitable backend is selected on the premise of
82 selecting a working backend (which for example rules out kqueue on most
83 BSDs). Modules should, unless they have "special needs" always use the
84 default loop as this is fastest (perl-wise), best supported by other
85 modules (e.g. AnyEvent or Coro) and most portable event loop.
86
87 For specific programs you can create additional event loops dynamically.
88
89 If you want to take advantage of kqueue (which often works properly for
90 sockets only) even though the default loop doesn't enable it, you can
91 *embed* a kqueue loop into the default loop: running the default loop
92 will then also service the kqueue loop to some extent. See the example
93 in the section about embed watchers for an example on how to achieve
94 that.
95
96 $loop = new EV::loop [$flags]
97 Create a new event loop as per the specified flags. Please refer to
98 the "ev_loop_new ()" function description in the libev documentation
99 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
100 ONS>, or locally-installed as EV::libev manpage) for more info.
101
102 The loop will automatically be destroyed when it is no longer
103 referenced by any watcher and the loop object goes out of scope.
104
105 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
106 is recommended, as only the default event loop is protected by this
107 module. If you *are* embedding this loop in the default loop, this
108 is not necessary, as "EV::embed" automatically does the right thing
109 on fork.
110
111 $loop->loop_fork
112 Must be called after a fork in the child, before entering or
113 continuing the event loop. An alternative is to use
114 "EV::FLAG_FORKCHECK" which calls this function automatically, at
115 some performance loss (refer to the libev documentation).
116
117 $loop->loop_verify
118 Calls "ev_verify" to make internal consistency checks (for debugging
119 libev) and abort the program if any data structures were found to be
120 corrupted.
121
122 $loop = EV::default_loop [$flags]
123 Return the default loop (which is a singleton object). Since this
124 module already creates the default loop with default flags,
125 specifying flags here will not have any effect unless you destroy
126 the default loop first, which isn't supported. So in short: don't do
127 it, and if you break it, you get to keep the pieces.
57 128
58BASIC INTERFACE 129BASIC INTERFACE
59 $EV::DIED 130 $EV::DIED
60 Must contain a reference to a function that is called when a 131 Must contain a reference to a function that is called when a
61 callback throws an exception (with $@ containing thr error). The 132 callback throws an exception (with $@ containing the error). The
62 default prints an informative message and continues. 133 default prints an informative message and continues.
63 134
64 If this callback throws an exception it will be silently ignored. 135 If this callback throws an exception it will be silently ignored.
136
137 $flags = EV::supported_backends
138 $flags = EV::recommended_backends
139 $flags = EV::embeddable_backends
140 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
141 this instance of EV, the set of recommended backends (supposed to be
142 good) for this platform and the set of embeddable backends (see
143 EMBED WATCHERS).
144
145 EV::sleep $seconds
146 Block the process for the given number of (fractional) seconds.
65 147
66 $time = EV::time 148 $time = EV::time
67 Returns the current time in (fractional) seconds since the epoch. 149 Returns the current time in (fractional) seconds since the epoch.
68 150
69 $time = EV::now 151 $time = EV::now
152 $time = $loop->now
70 Returns the time the last event loop iteration has been started. 153 Returns the time the last event loop iteration has been started.
71 This is the time that (relative) timers are based on, and refering 154 This is the time that (relative) timers are based on, and referring
72 to it is usually faster then calling EV::time. 155 to it is usually faster then calling EV::time.
73 156
74 $method = EV::ev_method 157 $backend = EV::backend
158 $backend = $loop->backend
75 Returns an integer describing the backend used by libev 159 Returns an integer describing the backend used by libev
76 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 160 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
77 161
78 EV::loop [$flags] 162 EV::loop [$flags]
163 $loop->loop ([$flags])
79 Begin checking for events and calling callbacks. It returns when a 164 Begin checking for events and calling callbacks. It returns when a
80 callback calls EV::loop_done. 165 callback calls EV::unloop.
81 166
82 The $flags argument can be one of the following: 167 The $flags argument can be one of the following:
83 168
84 0 as above 169 0 as above
85 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 170 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
86 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 171 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
87 172
88 EV::loop_done [$how] 173 EV::unloop [$how]
174 $loop->unloop ([$how])
89 When called with no arguments or an argument of 1, makes the 175 When called with no arguments or an argument of EV::UNLOOP_ONE,
90 innermost call to EV::loop return. 176 makes the innermost call to EV::loop return.
91 177
92 When called with an agrument of 2, all calls to EV::loop will return 178 When called with an argument of EV::UNLOOP_ALL, all calls to
93 as fast as possible. 179 EV::loop will return as fast as possible.
94 180
95 WATCHER 181 $count = EV::loop_count
182 $count = $loop->loop_count
183 Return the number of times the event loop has polled for new events.
184 Sometimes useful as a generation counter.
185
186 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
187 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
188 This function rolls together an I/O and a timer watcher for a single
189 one-shot event without the need for managing a watcher object.
190
191 If $fh_or_undef is a filehandle or file descriptor, then $events
192 must be a bitset containing either "EV::READ", "EV::WRITE" or
193 "EV::READ | EV::WRITE", indicating the type of I/O event you want to
194 wait for. If you do not want to wait for some I/O event, specify
195 "undef" for $fh_or_undef and 0 for $events).
196
197 If timeout is "undef" or negative, then there will be no timeout.
198 Otherwise a EV::timer with this value will be started.
199
200 When an error occurs or either the timeout or I/O watcher triggers,
201 then the callback will be called with the received event set (in
202 general you can expect it to be a combination of "EV::ERROR",
203 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
204
205 EV::once doesn't return anything: the watchers stay active till
206 either of them triggers, then they will be stopped and freed, and
207 the callback invoked.
208
209 EV::feed_fd_event ($fd, $revents)
210 $loop->feed_fd_event ($fd, $revents)
211 Feed an event on a file descriptor into EV. EV will react to this
212 call as if the readyness notifications specified by $revents (a
213 combination of "EV::READ" and "EV::WRITE") happened on the file
214 descriptor $fd.
215
216 EV::feed_signal_event ($signal)
217 Feed a signal event into EV. EV will react to this call as if the
218 signal specified by $signal had occured.
219
220 EV::set_io_collect_interval $time
221 $loop->set_io_collect_interval ($time)
222 EV::set_timeout_collect_interval $time
223 $loop->set_timeout_collect_interval ($time)
224 These advanced functions set the minimum block interval when polling
225 for I/O events and the minimum wait interval for timer events. See
226 the libev documentation at
227 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
228 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
229 detailed discussion.
230
231WATCHER OBJECTS
96 A watcher is an object that gets created to record your interest in some 232 A watcher is an object that gets created to record your interest in some
97 event. For instance, if you want to wait for STDIN to become readable, 233 event. For instance, if you want to wait for STDIN to become readable,
98 you would create an EV::io watcher for that: 234 you would create an EV::io watcher for that:
99 235
100 my $watcher = EV::io *STDIN, EV::READ, sub { 236 my $watcher = EV::io *STDIN, EV::READ, sub {
101 my ($watcher, $revents) = @_; 237 my ($watcher, $revents) = @_;
102 warn "yeah, STDIN should not be readable without blocking!\n" 238 warn "yeah, STDIN should now be readable without blocking!\n"
103 }; 239 };
104 240
105 All watchers can be active (waiting for events) or inactive (paused). 241 All watchers can be active (waiting for events) or inactive (paused).
106 Only active watchers will have their callbacks invoked. All callbacks 242 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 243 will be called with at least two arguments: the watcher and a bitmask of
108 received events. 244 received events.
109 245
110 Each watcher type has its associated bit in revents, so you can use the 246 Each watcher type has its associated bit in revents, so you can use the
111 same callback for multiple watchers. The event mask is named after the 247 same callback for multiple watchers. The event mask is named after the
112 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 248 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
113 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 249 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
114 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 250 events (which can set both EV::READ and EV::WRITE bits), and EV::timer
115 (which uses EV::TIMEOUT). 251 (which uses EV::TIMEOUT).
116 252
117 In the rare case where one wants to create a watcher but not start it at 253 In the rare case where one wants to create a watcher but not start it at
118 the same time, each constructor has a variant with a trailing "_ns" in 254 the same time, each constructor has a variant with a trailing "_ns" in
… …
124 260
125 Also, all methods changing some aspect of a watcher (->set, ->priority, 261 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, 262 ->fh and so on) automatically stop and start it again if it is active,
127 which means pending events get lost. 263 which means pending events get lost.
128 264
129 WATCHER TYPES 265 COMMON WATCHER METHODS
130 Now lets move to the existing watcher types and asociated methods. 266 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).
136 267
137 $w->start 268 $w->start
138 Starts a watcher if it isn't active already. Does nothing to an 269 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 270 already active watcher. By default, all watchers start out in the
140 active state (see the description of the "_ns" variants if you need 271 active state (see the description of the "_ns" variants if you need
141 stopped watchers). 272 stopped watchers).
142 273
143 $w->stop 274 $w->stop
144 Stop a watcher if it is active. Also clear any pending events 275 Stop a watcher if it is active. Also clear any pending events
145 (events that have been received but that didn't yet result in a 276 (events that have been received but that didn't yet result in a
146 callback invocation), regardless of wether the watcher was active or 277 callback invocation), regardless of whether the watcher was active
147 not. 278 or not.
148 279
149 $bool = $w->is_active 280 $bool = $w->is_active
150 Returns true if the watcher is active, false otherwise. 281 Returns true if the watcher is active, false otherwise.
151 282
152 $current_data = $w->data 283 $current_data = $w->data
… …
170 Pending watchers with higher priority will be invoked first. The 301 Pending watchers with higher priority will be invoked first. The
171 valid range of priorities lies between EV::MAXPRI (default 2) and 302 valid range of priorities lies between EV::MAXPRI (default 2) and
172 EV::MINPRI (default -2). If the priority is outside this range it 303 EV::MINPRI (default -2). If the priority is outside this range it
173 will automatically be normalised to the nearest valid priority. 304 will automatically be normalised to the nearest valid priority.
174 305
175 The default priority of any newly-created weatcher is 0. 306 The default priority of any newly-created watcher is 0.
176 307
308 Note that the priority semantics have not yet been fleshed out and
309 are subject to almost certain change.
310
177 $w->trigger ($revents) 311 $w->invoke ($revents)
178 Call the callback *now* with the given event mask. 312 Call the callback *now* with the given event mask.
179 313
314 $w->feed_event ($revents)
315 Feed some events on this watcher into EV. EV will react to this call
316 as if the watcher had received the given $revents mask.
317
318 $revents = $w->clear_pending
319 If the watcher is pending, this function clears its pending status
320 and returns its $revents bitset (as if its callback was invoked). If
321 the watcher isn't pending it does nothing and returns 0.
322
323 $previous_state = $w->keepalive ($bool)
324 Normally, "EV::loop" will return when there are no active watchers
325 (which is a "deadlock" because no progress can be made anymore).
326 This is convinient because it allows you to start your watchers (and
327 your jobs), call "EV::loop" once and when it returns you know that
328 all your jobs are finished (or they forgot to register some watchers
329 for their task :).
330
331 Sometimes, however, this gets in your way, for example when the
332 module that calls "EV::loop" (usually the main program) is not the
333 same module as a long-living watcher (for example a DNS client
334 module written by somebody else even). Then you might want any
335 outstanding requests to be handled, but you would not want to keep
336 "EV::loop" from returning just because you happen to have this
337 long-running UDP port watcher.
338
339 In this case you can clear the keepalive status, which means that
340 even though your watcher is active, it won't keep "EV::loop" from
341 returning.
342
343 The initial value for keepalive is true (enabled), and you can
344 change it any time.
345
346 Example: Register an I/O watcher for some UDP socket but do not keep
347 the event loop from running just because of that watcher.
348
349 my $udp_socket = ...
350 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
351 $udp_watcher->keepalive (0);
352
353 $loop = $w->loop
354 Return the loop that this watcher is attached to.
355
356WATCHER TYPES
357 Each of the following subsections describes a single watcher type.
358
359 I/O WATCHERS - is this file descriptor readable or writable?
180 $w = EV::io $fileno_or_fh, $eventmask, $callback 360 $w = EV::io $fileno_or_fh, $eventmask, $callback
181 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 361 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
362 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
363 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
182 As long as the returned watcher object is alive, call the $callback 364 As long as the returned watcher object is alive, call the $callback
183 when the events specified in $eventmask. 365 when at least one of events specified in $eventmask occurs.
184 366
185 The $eventmask can be one or more of these constants ORed together: 367 The $eventmask can be one or more of these constants ORed together:
186 368
187 EV::READ wait until read() wouldn't block anymore 369 EV::READ wait until read() wouldn't block anymore
188 EV::WRITE wait until write() wouldn't block anymore 370 EV::WRITE wait until write() wouldn't block anymore
… …
200 382
201 $current_eventmask = $w->events 383 $current_eventmask = $w->events
202 $old_eventmask = $w->events ($new_eventmask) 384 $old_eventmask = $w->events ($new_eventmask)
203 Returns the previously set event mask and optionally set a new one. 385 Returns the previously set event mask and optionally set a new one.
204 386
387 TIMER WATCHERS - relative and optionally repeating timeouts
205 $w = EV::timer $after, $repeat, $callback 388 $w = EV::timer $after, $repeat, $callback
206 $w = EV::timer_ns $after, $repeat, $callback 389 $w = EV::timer_ns $after, $repeat, $callback
207 Calls the callback after $after seconds. If $repeat is non-zero, the 390 $w = $loop->timer ($after, $repeat, $callback)
208 timer will be restarted (with the $repeat value as $after) after the 391 $w = $loop->timer_ns ($after, $repeat, $callback)
209 callback returns. 392 Calls the callback after $after seconds (which may be fractional).
393 If $repeat is non-zero, the timer will be restarted (with the
394 $repeat value as $after) after the callback returns.
210 395
211 This means that the callback would be called roughly after $after 396 This means that the callback would be called roughly after $after
212 seconds, and then every $repeat seconds. "Roughly" because the time 397 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 398 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. 399 event loop iteration, and might drift in other cases. If that isn't
400 acceptable, look at EV::periodic, which can provide long-term stable
401 timers.
215 402
216 The timer is based on a monotonic clock, that is if somebody is 403 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 404 sitting in front of the machine while the timer is running and
218 changes the system clock, the timer will nevertheless run (roughly) 405 changes the system clock, the timer will nevertheless run (roughly)
219 the same time. 406 the same time.
220 407
221 The "timer_ns" variant doesn't start (activate) the newly created 408 The "timer_ns" variant doesn't start (activate) the newly created
222 watcher. 409 watcher.
223 410
224 $w->set ($after, $repeat) 411 $w->set ($after, $repeat)
225 Reconfigures the watcher, see the constructor above for details. Can 412 Reconfigures the watcher, see the constructor above for details. Can
226 be at any time. 413 be called at any time.
227 414
228 $w->again 415 $w->again
229 Similar to the "start" method, but has special semantics for 416 Similar to the "start" method, but has special semantics for
230 repeating timers: 417 repeating timers:
231 418
419 If the timer is active and non-repeating, it will be stopped.
420
232 If the timer is active and repeating, reset the timeout to occur 421 If the timer is active and repeating, reset the timeout to occur
233 $repeat seconds after now. 422 $repeat seconds after now.
234 423
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. 424 If the timer is inactive and repeating, start it using the repeat
425 value.
238 426
239 Otherwise do nothing. 427 Otherwise do nothing.
240 428
241 This behaviour is useful when you have a timeout for some IO 429 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 430 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" 431 and $repeat, and then, in the read/write watcher, run the "again"
244 method on the timeout. 432 method on the timeout.
245 433
434 PERIODIC WATCHERS - to cron or not to cron?
246 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 435 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
247 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 436 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
437 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
438 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
248 Similar to EV::timer, but is not based on relative timeouts but on 439 Similar to EV::timer, but is not based on relative timeouts but on
249 absolute times. Apart from creating "simple" timers that trigger 440 absolute times. Apart from creating "simple" timers that trigger
250 "at" the specified time, it can also be used for non-drifting 441 "at" the specified time, it can also be used for non-drifting
251 absolute timers and more complex, cron-like, setups that are not 442 absolute timers and more complex, cron-like, setups that are not
252 adversely affected by time jumps (i.e. when the system clock is 443 adversely affected by time jumps (i.e. when the system clock is
253 changed by explicit date -s or other means such as ntpd). It is also 444 changed by explicit date -s or other means such as ntpd). It is also
254 the most complex watcher type in EV. 445 the most complex watcher type in EV.
255 446
256 It has three distinct "modes": 447 It has three distinct "modes":
257 448
258 * absolute timer ($interval = $reschedule_cb = 0) 449 * absolute timer ($interval = $reschedule_cb = 0)
450
259 This time simply fires at the wallclock time $at and doesn't 451 This time simply fires at the wallclock time $at and doesn't
260 repeat. It will not adjust when a time jump occurs, that is, if 452 repeat. It will not adjust when a time jump occurs, that is, if
261 it is to be run at January 1st 2011 then it will run when the 453 it is to be run at January 1st 2011 then it will run when the
262 system time reaches or surpasses this time. 454 system time reaches or surpasses this time.
263 455
264 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 456 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
457
265 In this mode the watcher will always be scheduled to time out at 458 In this mode the watcher will always be scheduled to time out at
266 the next "$at + N * $interval" time (for some integer N) and 459 the next "$at + N * $interval" time (for some integer N) and
267 then repeat, regardless of any time jumps. 460 then repeat, regardless of any time jumps.
268 461
269 This can be used to create timers that do not drift with respect 462 This can be used to create timers that do not drift with respect
… …
278 Another way to think about it (for the mathematically inclined) 471 Another way to think about it (for the mathematically inclined)
279 is that EV::periodic will try to run the callback in this mode 472 is that EV::periodic will try to run the callback in this mode
280 at the next possible time where "$time = $at (mod $interval)", 473 at the next possible time where "$time = $at (mod $interval)",
281 regardless of any time jumps. 474 regardless of any time jumps.
282 475
283 * manual reschedule mode ($reschedule_cb = coderef) 476 * manual reschedule mode ($reschedule_cb = coderef)
477
284 In this mode $interval and $at are both being ignored. Instead, 478 In this mode $interval and $at are both being ignored. Instead,
285 each time the periodic watcher gets scheduled, the first 479 each time the periodic watcher gets scheduled, the reschedule
286 callback ($reschedule_cb) will be called with the watcher as 480 callback ($reschedule_cb) will be called with the watcher as
287 first, and the current time as second argument. 481 first, and the current time as second argument.
288 482
289 *This callback MUST NOT stop or destroy this or any other 483 *This callback MUST NOT stop or destroy this or any other
484 periodic watcher, ever, and MUST NOT call any event loop
290 periodic watcher, ever*. If you need to stop it, return 1e30 and 485 functions or methods*. If you need to stop it, return 1e30 and
291 stop it afterwards. 486 stop it afterwards. You may create and start a "EV::prepare"
487 watcher for this task.
292 488
293 It must return the next time to trigger, based on the passed 489 It must return the next time to trigger, based on the passed
294 time value (that is, the lowest time value larger than to the 490 time value (that is, the lowest time value larger than or equal
295 second argument). It will usually be called just before the 491 to to the second argument). It will usually be called just
296 callback will be triggered, but might be called at other times, 492 before the callback will be triggered, but might be called at
297 too. 493 other times, too.
298 494
299 This can be used to create very complex timers, such as a timer 495 This can be used to create very complex timers, such as a timer
300 that triggers on each midnight, local time (actually 24 hours 496 that triggers on each midnight, local time (actually 24 hours
301 after the last midnight, to keep the example simple. If you know 497 after the last midnight, to keep the example simple. If you know
302 a way to do it correctly in about the same space (without 498 a way to do it correctly in about the same space (without
… …
315 The "periodic_ns" variant doesn't start (activate) the newly created 511 The "periodic_ns" variant doesn't start (activate) the newly created
316 watcher. 512 watcher.
317 513
318 $w->set ($at, $interval, $reschedule_cb) 514 $w->set ($at, $interval, $reschedule_cb)
319 Reconfigures the watcher, see the constructor above for details. Can 515 Reconfigures the watcher, see the constructor above for details. Can
320 be at any time. 516 be called at any time.
321 517
322 $w->again 518 $w->again
323 Simply stops and starts the watcher again. 519 Simply stops and starts the watcher again.
324 520
521 $time = $w->at
522 Return the time that the watcher is expected to trigger next.
523
524 SIGNAL WATCHERS - signal me when a signal gets signalled!
325 $w = EV::signal $signal, $callback 525 $w = EV::signal $signal, $callback
326 $w = EV::signal_ns $signal, $callback 526 $w = EV::signal_ns $signal, $callback
327 Call the callback when $signal is received (the signal can be 527 Call the callback when $signal is received (the signal can be
328 specified by number or by name, just as with kill or %SIG). 528 specified by number or by name, just as with "kill" or %SIG).
329 529
330 EV will grab the signal for the process (the kernel only allows one 530 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 531 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 532 watcher, and removes it again when you stop it. Perl does the same
333 when you add/remove callbacks to %SIG, so watch out. 533 when you add/remove callbacks to %SIG, so watch out.
… …
337 The "signal_ns" variant doesn't start (activate) the newly created 537 The "signal_ns" variant doesn't start (activate) the newly created
338 watcher. 538 watcher.
339 539
340 $w->set ($signal) 540 $w->set ($signal)
341 Reconfigures the watcher, see the constructor above for details. Can 541 Reconfigures the watcher, see the constructor above for details. Can
342 be at any time. 542 be called at any time.
343 543
344 $current_signum = $w->signal 544 $current_signum = $w->signal
345 $old_signum = $w->signal ($new_signal) 545 $old_signum = $w->signal ($new_signal)
346 Returns the previously set signal (always as a number not name) and 546 Returns the previously set signal (always as a number not name) and
347 optionally set a new one. 547 optionally set a new one.
348 548
549 CHILD WATCHERS - watch out for process status changes
349 $w = EV::child $pid, $callback 550 $w = EV::child $pid, $trace, $callback
350 $w = EV::child_ns $pid, $callback 551 $w = EV::child_ns $pid, $trace, $callback
552 $w = $loop->child ($pid, $trace, $callback)
553 $w = $loop->child_ns ($pid, $trace, $callback)
351 Call the callback when a status change for pid $pid (or any pid if 554 Call the callback when a status change for pid $pid (or any pid if
352 $pid is 0) has been received. More precisely: when the process 555 $pid is 0) has been received (a status change happens when the
556 process terminates or is killed, or, when trace is true,
557 additionally when it is stopped or continued). More precisely: when
353 receives a SIGCHLD, EV will fetch the outstanding exit/wait status 558 the process receives a "SIGCHLD", EV will fetch the outstanding
354 for all changed/zombie children and call the callback. 559 exit/wait status for all changed/zombie children and call the
560 callback.
355 561
356 You can access both status and pid by using the "rstatus" and "rpid" 562 It is valid (and fully supported) to install a child watcher after a
563 child has exited but before the event loop has started its next
564 iteration (for example, first you "fork", then the new child process
565 might exit, and only then do you install a child watcher in the
566 parent for the new pid).
567
568 You can access both exit (or tracing) status and pid by using the
357 methods on the watcher object. 569 "rstatus" and "rpid" methods on the watcher object.
358 570
359 You can have as many pid watchers per pid as you want. 571 You can have as many pid watchers per pid as you want, they will all
572 be called.
360 573
361 The "child_ns" variant doesn't start (activate) the newly created 574 The "child_ns" variant doesn't start (activate) the newly created
362 watcher. 575 watcher.
363 576
364 $w->set ($pid) 577 $w->set ($pid, $trace)
365 Reconfigures the watcher, see the constructor above for details. Can 578 Reconfigures the watcher, see the constructor above for details. Can
366 be at any time. 579 be called at any time.
367 580
368 $current_pid = $w->pid 581 $current_pid = $w->pid
369 $old_pid = $w->pid ($new_pid)
370 Returns the previously set process id and optionally set a new one. 582 Returns the previously set process id and optionally set a new one.
371 583
372 $exit_status = $w->rstatus 584 $exit_status = $w->rstatus
373 Return the exit/wait status (as returned by waitpid, see the waitpid 585 Return the exit/wait status (as returned by waitpid, see the waitpid
374 entry in perlfunc). 586 entry in perlfunc).
375 587
376 $pid = $w->rpid 588 $pid = $w->rpid
377 Return the pid of the awaited child (useful when you have installed 589 Return the pid of the awaited child (useful when you have installed
378 a watcher for all pids). 590 a watcher for all pids).
379 591
592 STAT WATCHERS - did the file attributes just change?
593 $w = EV::stat $path, $interval, $callback
594 $w = EV::stat_ns $path, $interval, $callback
595 $w = $loop->stat ($path, $interval, $callback)
596 $w = $loop->stat_ns ($path, $interval, $callback)
597 Call the callback when a file status change has been detected on
598 $path. The $path does not need to exist, changing from "path exists"
599 to "path does not exist" is a status change like any other.
600
601 The $interval is a recommended polling interval for systems where
602 OS-supported change notifications don't exist or are not supported.
603 If you use 0 then an unspecified default is used (which is highly
604 recommended!), which is to be expected to be around five seconds
605 usually.
606
607 This watcher type is not meant for massive numbers of stat watchers,
608 as even with OS-supported change notifications, this can be
609 resource-intensive.
610
611 The "stat_ns" variant doesn't start (activate) the newly created
612 watcher.
613
614 ... = $w->stat
615 This call is very similar to the perl "stat" built-in: It stats
616 (using "lstat") the path specified in the watcher and sets perls
617 stat cache (as well as EV's idea of the current stat values) to the
618 values found.
619
620 In scalar context, a boolean is return indicating success or failure
621 of the stat. In list context, the same 13-value list as with stat is
622 returned (except that the blksize and blocks fields are not
623 reliable).
624
625 In the case of an error, errno is set to "ENOENT" (regardless of the
626 actual error value) and the "nlink" value is forced to zero (if the
627 stat was successful then nlink is guaranteed to be non-zero).
628
629 See also the next two entries for more info.
630
631 ... = $w->attr
632 Just like "$w->stat", but without the initial stat'ing: this returns
633 the values most recently detected by EV. See the next entry for more
634 info.
635
636 ... = $w->prev
637 Just like "$w->stat", but without the initial stat'ing: this returns
638 the previous set of values, before the change.
639
640 That is, when the watcher callback is invoked, "$w->prev" will be
641 set to the values found *before* a change was detected, while
642 "$w->attr" returns the values found leading to the change detection.
643 The difference (if any) between "prev" and "attr" is what triggered
644 the callback.
645
646 If you did something to the filesystem object and do not want to
647 trigger yet another change, you can call "stat" to update EV's idea
648 of what the current attributes are.
649
650 $w->set ($path, $interval)
651 Reconfigures the watcher, see the constructor above for details. Can
652 be called at any time.
653
654 $current_path = $w->path
655 $old_path = $w->path ($new_path)
656 Returns the previously set path and optionally set a new one.
657
658 $current_interval = $w->interval
659 $old_interval = $w->interval ($new_interval)
660 Returns the previously set interval and optionally set a new one.
661 Can be used to query the actual interval used.
662
663 IDLE WATCHERS - when you've got nothing better to do...
380 $w = EV::idle $callback 664 $w = EV::idle $callback
381 $w = EV::idle_ns $callback 665 $w = EV::idle_ns $callback
666 $w = $loop->idle ($callback)
667 $w = $loop->idle_ns ($callback)
382 Call the callback when there are no pending io, timer/periodic, 668 Call the callback when there are no other pending watchers of the
383 signal or child events, i.e. when the process is idle. 669 same or higher priority (excluding check, prepare and other idle
670 watchers of the same or lower priority, of course). They are called
671 idle watchers because when the watcher is the highest priority
672 pending event in the process, the process is considered to be idle
673 at that priority.
674
675 If you want a watcher that is only ever called when *no* other
676 events are outstanding you have to set the priority to "EV::MINPRI".
384 677
385 The process will not block as long as any idle watchers are active, 678 The process will not block as long as any idle watchers are active,
386 and they will be called repeatedly until stopped. 679 and they will be called repeatedly until stopped.
387 680
681 For example, if you have idle watchers at priority 0 and 1, and an
682 I/O watcher at priority 0, then the idle watcher at priority 1 and
683 the I/O watcher will always run when ready. Only when the idle
684 watcher at priority 1 is stopped and the I/O watcher at priority 0
685 is not pending with the 0-priority idle watcher be invoked.
686
388 The "idle_ns" variant doesn't start (activate) the newly created 687 The "idle_ns" variant doesn't start (activate) the newly created
389 watcher. 688 watcher.
390 689
690 PREPARE WATCHERS - customise your event loop!
391 $w = EV::prepare $callback 691 $w = EV::prepare $callback
392 $w = EV::prepare_ns $callback 692 $w = EV::prepare_ns $callback
693 $w = $loop->prepare ($callback)
694 $w = $loop->prepare_ns ($callback)
393 Call the callback just before the process would block. You can still 695 Call the callback just before the process would block. You can still
394 create/modify any watchers at this point. 696 create/modify any watchers at this point.
395 697
396 See the EV::check watcher, below, for explanations and an example. 698 See the EV::check watcher, below, for explanations and an example.
397 699
398 The "prepare_ns" variant doesn't start (activate) the newly created 700 The "prepare_ns" variant doesn't start (activate) the newly created
399 watcher. 701 watcher.
400 702
703 CHECK WATCHERS - customise your event loop even more!
401 $w = EV::check $callback 704 $w = EV::check $callback
402 $w = EV::check_ns $callback 705 $w = EV::check_ns $callback
706 $w = $loop->check ($callback)
707 $w = $loop->check_ns ($callback)
403 Call the callback just after the process wakes up again (after it 708 Call the callback just after the process wakes up again (after it
404 has gathered events), but before any other callbacks have been 709 has gathered events), but before any other callbacks have been
405 invoked. 710 invoked.
406 711
407 This is used to integrate other event-based software into the EV 712 This is used to integrate other event-based software into the EV
… …
416 # do nothing unless active 721 # do nothing unless active
417 $dispatcher->{_event_queue_h} 722 $dispatcher->{_event_queue_h}
418 or return; 723 or return;
419 724
420 # make the dispatcher handle any outstanding stuff 725 # make the dispatcher handle any outstanding stuff
726 ... not shown
421 727
422 # create an IO watcher for each and every socket 728 # create an I/O watcher for each and every socket
423 @snmp_watcher = ( 729 @snmp_watcher = (
424 (map { EV::io $_, EV::READ, sub { } } 730 (map { EV::io $_, EV::READ, sub { } }
425 keys %{ $dispatcher->{_descriptors} }), 731 keys %{ $dispatcher->{_descriptors} }),
732
733 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
734 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
735 0, sub { },
426 ); 736 );
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 }; 737 };
432 738
433 The callbacks are irrelevant, the only purpose of those watchers is 739 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 740 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 741 one of those events occurs (socket readable, or timer timed out).
436 will then clean up: 742 The corresponding EV::check watcher will then clean up:
437 743
438 our $snmp_check = EV::check sub { 744 our $snmp_check = EV::check sub {
439 # destroy all watchers 745 # destroy all watchers
440 @snmp_watcher = (); 746 @snmp_watcher = ();
441 747
442 # make the dispatcher handle any new stuff 748 # make the dispatcher handle any new stuff
749 ... not shown
443 }; 750 };
444 751
445 The callbacks of the created watchers will not be called as the 752 The callbacks of the created watchers will not be called as the
446 watchers are destroyed before this cna happen (remember EV::check 753 watchers are destroyed before this can happen (remember EV::check
447 gets called first). 754 gets called first).
448 755
449 The "check_ns" variant doesn't start (activate) the newly created 756 The "check_ns" variant doesn't start (activate) the newly created
450 watcher. 757 watcher.
451 758
759 FORK WATCHERS - the audacity to resume the event loop after a fork
760 Fork watchers are called when a "fork ()" was detected. The invocation
761 is done before the event loop blocks next and before "check" watchers
762 are being called, and only in the child after the fork.
763
764 $w = EV::fork $callback
765 $w = EV::fork_ns $callback
766 $w = $loop->fork ($callback)
767 $w = $loop->fork_ns ($callback)
768 Call the callback before the event loop is resumed in the child
769 process after a fork.
770
771 The "fork_ns" variant doesn't start (activate) the newly created
772 watcher.
773
774 EMBED WATCHERS - when one backend isn't enough...
775 This is a rather advanced watcher type that lets you embed one event
776 loop into another (currently only IO events are supported in the
777 embedded loop, other types of watchers might be handled in a delayed or
778 incorrect fashion and must not be used).
779
780 See the libev documentation at
781 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
782 _when_one_backend_> (locally installed as EV::libev) for more details.
783
784 In short, this watcher is most useful on BSD systems without working
785 kqueue to still be able to handle a large number of sockets:
786
787 my $socket_loop;
788
789 # check wether we use SELECT or POLL _and_ KQUEUE is supported
790 if (
791 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
792 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
793 ) {
794 # use kqueue for sockets
795 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
796 }
797
798 # use the default loop otherwise
799 $socket_loop ||= EV::default_loop;
800
801 $w = EV::embed $otherloop[, $callback]
802 $w = EV::embed_ns $otherloop[, $callback]
803 $w = $loop->embed ($otherloop[, $callback])
804 $w = $loop->embed_ns ($otherloop[, $callback])
805 Call the callback when the embedded event loop ($otherloop) has any
806 I/O activity. The $callback is optional: if it is missing, then the
807 embedded event loop will be managed automatically (which is
808 recommended), otherwise you have to invoke "sweep" yourself.
809
810 The "embed_ns" variant doesn't start (activate) the newly created
811 watcher.
812
813 ASYNC WATCHERS - how to wake up another event loop
814 Async watchers are provided by EV, but have little use in perl directly,
815 as perl neither supports threads nor direct access to signal handlers or
816 other contexts where they could be of value.
817
818 It is, however, possible to use them from the XS level.
819
820 Please see the libev documentation for further details.
821
822 $w = EV::async $callback
823 $w = EV::async_ns $callback
824 $w->send
825 $bool = $w->async_pending
826
827PERL SIGNALS
828 While Perl signal handling (%SIG) is not affected by EV, the behaviour
829 with EV is as the same as any other C library: Perl-signals will only be
830 handled when Perl runs, which means your signal handler might be invoked
831 only the next time an event callback is invoked.
832
833 The solution is to use EV signal watchers (see "EV::signal"), which will
834 ensure proper operations with regards to other event watchers.
835
836 If you cannot do this for whatever reason, you can also force a watcher
837 to be called on every event loop iteration by installing a "EV::check"
838 watcher:
839
840 my $async_check = EV::check sub { };
841
842 This ensures that perl gets into control for a short time to handle any
843 pending signals, and also ensures (slightly) slower overall operation.
844
452THREADS 845THREADS
453 Threads are not supported by this in any way. Perl pseudo-threads is 846 Threads are not supported by this module in any way. Perl pseudo-threads
454 evil stuff and must die. 847 is evil stuff and must die. As soon as Perl gains real threads I will
848 work on thread support for it.
849
850FORK
851 Most of the "improved" event delivering mechanisms of modern operating
852 systems have quite a few problems with fork(2) (to put it bluntly: it is
853 not supported and usually destructive). Libev makes it possible to work
854 around this by having a function that recreates the kernel state after
855 fork in the child.
856
857 On non-win32 platforms, this module requires the pthread_atfork
858 functionality to do this automatically for you. This function is quite
859 buggy on most BSDs, though, so YMMV. The overhead for this is quite
860 negligible, because everything the function currently does is set a flag
861 that is checked only when the event loop gets used the next time, so
862 when you do fork but not use EV, the overhead is minimal.
863
864 On win32, there is no notion of fork so all this doesn't apply, of
865 course.
455 866
456SEE ALSO 867SEE ALSO
457 L<EV::DNS>, L<EV::AnyEvent>. 868 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
869 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
870 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
871 agnostic and portable event driven programming.
458 872
459AUTHOR 873AUTHOR
460 Marc Lehmann <schmorp@schmorp.de> 874 Marc Lehmann <schmorp@schmorp.de>
461 http://home.schmorp.de/ 875 http://home.schmorp.de/
462 876

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