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1NAME 1NAME
2 EV - perl interface to libev, a high performance full-featured event 2 EV - perl interface to libev, a high performance full-featured event
3 loop 3 loop
4 4
5SYNOPSIS 5SYNOPSIS
6 use EV; 6 use EV;
7
8 # TIMERS
9
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
7 38
8 # TIMERS 39 my $w = EV::child 666, 0, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
9 43
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
38
39 my $w = EV::child 666, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
43
44 # STAT CHANGES 44 # STAT CHANGES
45 my $w = EV::stat "/etc/passwd", 10, sub { 45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_; 46 my ($w, $revents) = @_;
47 warn $w->path, " has changed somehow.\n"; 47 warn $w->path, " has changed somehow.\n";
48 }; 48 };
49 49
50 # MAINLOOP 50 # MAINLOOP
51 EV::loop; # loop until EV::unloop is called or all watchers stop 51 EV::loop; # loop until EV::unloop is called or all watchers stop
52 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 52 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
53 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 53 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
54
55BEFORE YOU START USING THIS MODULE
56 If you only need timer, I/O, signal, child and idle watchers and not the
57 advanced functionality of this module, consider using AnyEvent instead,
58 specifically the simplified API described in AE.
59
60 When used with EV as backend, the AE API is as fast as the native EV
61 API, but your programs/modules will still run with many other event
62 loops.
54 63
55DESCRIPTION 64DESCRIPTION
56 This module provides an interface to libev 65 This module provides an interface to libev
57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation 66 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
58 below is comprehensive, one might also consult the documentation of 67 below is comprehensive, one might also consult the documentation of
59 libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle 68 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
60 details on watcher semantics or some discussion on the available 69 perldoc EV::libev) for more subtle details on watcher semantics or some
61 backends, or how to force a specific backend with "LIBEV_FLAGS". 70 discussion on the available backends, or how to force a specific backend
71 with "LIBEV_FLAGS", or just about in any case because it has much more
72 detailed information.
73
74 This module is very fast and scalable. It is actually so fast that you
75 can use it through the AnyEvent module, stay portable to other event
76 loops (if you don't rely on any watcher types not available through it)
77 and still be faster than with any other event loop currently supported
78 in Perl.
79
80 PORTING FROM EV 3.X to 4.X
81 EV version 4 introduces a number of incompatible changes summarised
82 here. According to the depreciation strategy used by libev, there is a
83 compatibility layer in place so programs should continue to run
84 unchanged (the XS interface lacks this layer, so programs using that one
85 need to be updated).
86
87 This compatibility layer will be switched off in some future release.
88
89 All changes relevant to Perl are renames of symbols, functions and
90 methods:
91
92 EV::loop => EV::run
93 EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
94 EV::LOOP_ONESHOT => EV::RUN_ONCE
95
96 EV::unloop => EV::break
97 EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
98 EV::UNLOOP_ONE => EV::BREAK_ONE
99 EV::UNLOOP_ALL => EV::BREAK_ALL
100
101 EV::TIMEOUT => EV::TIMER
102
103 EV::loop_count => EV::iteration
104 EV::loop_depth => EV::depth
105 EV::loop_verify => EV::verify
106
107 The loop object methods corresponding to the functions above have been
108 similarly renamed.
109
110 MODULE EXPORTS
111 This module does not export any symbols.
112
113EVENT LOOPS
114 EV supports multiple event loops: There is a single "default event loop"
115 that can handle everything including signals and child watchers, and any
116 number of "dynamic event loops" that can use different backends (with
117 various limitations), but no child and signal watchers.
118
119 You do not have to do anything to create the default event loop: When
120 the module is loaded a suitable backend is selected on the premise of
121 selecting a working backend (which for example rules out kqueue on most
122 BSDs). Modules should, unless they have "special needs" always use the
123 default loop as this is fastest (perl-wise), best supported by other
124 modules (e.g. AnyEvent or Coro) and most portable event loop.
125
126 For specific programs you can create additional event loops dynamically.
127
128 If you want to take advantage of kqueue (which often works properly for
129 sockets only) even though the default loop doesn't enable it, you can
130 *embed* a kqueue loop into the default loop: running the default loop
131 will then also service the kqueue loop to some extent. See the example
132 in the section about embed watchers for an example on how to achieve
133 that.
134
135 $loop = new EV::Loop [$flags]
136 Create a new event loop as per the specified flags. Please refer to
137 the "ev_loop_new ()" function description in the libev documentation
138 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
139 ONS>, or locally-installed as EV::libev manpage) for more info.
140
141 The loop will automatically be destroyed when it is no longer
142 referenced by any watcher and the loop object goes out of scope.
143
144 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
145 is recommended, as only the default event loop is protected by this
146 module. If you *are* embedding this loop in the default loop, this
147 is not necessary, as "EV::embed" automatically does the right thing
148 on fork.
149
150 $loop->loop_fork
151 Must be called after a fork in the child, before entering or
152 continuing the event loop. An alternative is to use
153 "EV::FLAG_FORKCHECK" which calls this function automatically, at
154 some performance loss (refer to the libev documentation).
155
156 $loop->loop_verify
157 Calls "ev_verify" to make internal consistency checks (for debugging
158 libev) and abort the program if any data structures were found to be
159 corrupted.
160
161 $loop = EV::default_loop [$flags]
162 Return the default loop (which is a singleton object). Since this
163 module already creates the default loop with default flags,
164 specifying flags here will not have any effect unless you destroy
165 the default loop first, which isn't supported. So in short: don't do
166 it, and if you break it, you get to keep the pieces.
62 167
63BASIC INTERFACE 168BASIC INTERFACE
64 $EV::DIED 169 $EV::DIED
65 Must contain a reference to a function that is called when a 170 Must contain a reference to a function that is called when a
66 callback throws an exception (with $@ containing thr error). The 171 callback throws an exception (with $@ containing the error). The
67 default prints an informative message and continues. 172 default prints an informative message and continues.
68 173
69 If this callback throws an exception it will be silently ignored. 174 If this callback throws an exception it will be silently ignored.
175
176 $flags = EV::supported_backends
177 $flags = EV::recommended_backends
178 $flags = EV::embeddable_backends
179 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
180 this instance of EV, the set of recommended backends (supposed to be
181 good) for this platform and the set of embeddable backends (see
182 EMBED WATCHERS).
183
184 EV::sleep $seconds
185 Block the process for the given number of (fractional) seconds.
70 186
71 $time = EV::time 187 $time = EV::time
72 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
73 189
74 $time = EV::now 190 $time = EV::now
191 $time = $loop->now
75 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
76 This is the time that (relative) timers are based on, and refering 193 This is the time that (relative) timers are based on, and referring
77 to it is usually faster then calling EV::time. 194 to it is usually faster then calling EV::time.
78 195
79 $method = EV::method 196 EV::now_update
197 $loop->now_update
198 Establishes the current time by querying the kernel, updating the
199 time returned by "EV::now" in the progress. This is a costly
200 operation and is usually done automatically within "EV::loop".
201
202 This function is rarely useful, but when some event callback runs
203 for a very long time without entering the event loop, updating
204 libev's idea of the current time is a good idea.
205
206 EV::suspend
207 $loop->suspend
208 EV::resume
209 $loop->resume
210 These two functions suspend and resume a loop, for use when the loop
211 is not used for a while and timeouts should not be processed.
212
213 A typical use case would be an interactive program such as a game:
214 When the user presses "^Z" to suspend the game and resumes it an
215 hour later it would be best to handle timeouts as if no time had
216 actually passed while the program was suspended. This can be
217 achieved by calling "suspend" in your "SIGTSTP" handler, sending
218 yourself a "SIGSTOP" and calling "resume" directly afterwards to
219 resume timer processing.
220
221 Effectively, all "timer" watchers will be delayed by the time spend
222 between "suspend" and "resume", and all "periodic" watchers will be
223 rescheduled (that is, they will lose any events that would have
224 occured while suspended).
225
226 After calling "suspend" you must not call *any* function on the
227 given loop other than "resume", and you must not call "resume"
228 without a previous call to "suspend".
229
230 Calling "suspend"/"resume" has the side effect of updating the event
231 loop time (see "now_update").
232
233 $backend = EV::backend
234 $backend = $loop->backend
80 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
81 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
82 237
83 EV::loop [$flags] 238 EV::loop [$flags]
239 $loop->loop ([$flags])
84 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
85 callback calls EV::unloop. 241 callback calls EV::unloop.
86 242
87 The $flags argument can be one of the following: 243 The $flags argument can be one of the following:
88 244
89 0 as above 245 0 as above
90 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 246 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
91 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 247 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
92 248
93 EV::unloop [$how] 249 EV::unloop [$how]
250 $loop->unloop ([$how])
94 When called with no arguments or an argument of EV::UNLOOP_ONE, 251 When called with no arguments or an argument of EV::UNLOOP_ONE,
95 makes the innermost call to EV::loop return. 252 makes the innermost call to EV::loop return.
96 253
97 When called with an argument of EV::UNLOOP_ALL, all calls to 254 When called with an argument of EV::UNLOOP_ALL, all calls to
98 EV::loop will return as fast as possible. 255 EV::loop will return as fast as possible.
99 256
257 $count = EV::loop_count
258 $count = $loop->loop_count
259 Return the number of times the event loop has polled for new events.
260 Sometimes useful as a generation counter.
261
100 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 262 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
263 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
101 This function rolls together an I/O and a timer watcher for a single 264 This function rolls together an I/O and a timer watcher for a single
102 one-shot event without the need for managing a watcher object. 265 one-shot event without the need for managing a watcher object.
103 266
104 If $fh_or_undef is a filehandle or file descriptor, then $events 267 If $fh_or_undef is a filehandle or file descriptor, then $events
105 must be a bitset containing either "EV::READ", "EV::WRITE" or 268 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
110 If timeout is "undef" or negative, then there will be no timeout. 273 If timeout is "undef" or negative, then there will be no timeout.
111 Otherwise a EV::timer with this value will be started. 274 Otherwise a EV::timer with this value will be started.
112 275
113 When an error occurs or either the timeout or I/O watcher triggers, 276 When an error occurs or either the timeout or I/O watcher triggers,
114 then the callback will be called with the received event set (in 277 then the callback will be called with the received event set (in
115 general you can expect it to be a combination of "EV:ERROR", 278 general you can expect it to be a combination of "EV::ERROR",
116 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 279 "EV::READ", "EV::WRITE" and "EV::TIMER").
117 280
118 EV::once doesn't return anything: the watchers stay active till 281 EV::once doesn't return anything: the watchers stay active till
119 either of them triggers, then they will be stopped and freed, and 282 either of them triggers, then they will be stopped and freed, and
120 the callback invoked. 283 the callback invoked.
121 284
285 EV::feed_fd_event ($fd, $revents)
286 $loop->feed_fd_event ($fd, $revents)
287 Feed an event on a file descriptor into EV. EV will react to this
288 call as if the readyness notifications specified by $revents (a
289 combination of "EV::READ" and "EV::WRITE") happened on the file
290 descriptor $fd.
291
292 EV::feed_signal_event ($signal)
293 Feed a signal event into EV. EV will react to this call as if the
294 signal specified by $signal had occured.
295
296 EV::set_io_collect_interval $time
297 $loop->set_io_collect_interval ($time)
298 EV::set_timeout_collect_interval $time
299 $loop->set_timeout_collect_interval ($time)
300 These advanced functions set the minimum block interval when polling
301 for I/O events and the minimum wait interval for timer events. See
302 the libev documentation at
303 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
304 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
305 detailed discussion.
306
307 $count = EV::pending_count
308 $count = $loop->pending_count
309 Returns the number of currently pending watchers.
310
311 EV::invoke_pending
312 $loop->invoke_pending
313 Invoke all currently pending watchers.
314
122 WATCHER OBJECTS 315WATCHER OBJECTS
123 A watcher is an object that gets created to record your interest in some 316 A watcher is an object that gets created to record your interest in some
124 event. For instance, if you want to wait for STDIN to become readable, 317 event. For instance, if you want to wait for STDIN to become readable,
125 you would create an EV::io watcher for that: 318 you would create an EV::io watcher for that:
126 319
127 my $watcher = EV::io *STDIN, EV::READ, sub { 320 my $watcher = EV::io *STDIN, EV::READ, sub {
128 my ($watcher, $revents) = @_; 321 my ($watcher, $revents) = @_;
129 warn "yeah, STDIN should not be readable without blocking!\n" 322 warn "yeah, STDIN should now be readable without blocking!\n"
130 }; 323 };
131 324
132 All watchers can be active (waiting for events) or inactive (paused). 325 All watchers can be active (waiting for events) or inactive (paused).
133 Only active watchers will have their callbacks invoked. All callbacks 326 Only active watchers will have their callbacks invoked. All callbacks
134 will be called with at least two arguments: the watcher and a bitmask of 327 will be called with at least two arguments: the watcher and a bitmask of
135 received events. 328 received events.
136 329
137 Each watcher type has its associated bit in revents, so you can use the 330 Each watcher type has its associated bit in revents, so you can use the
138 same callback for multiple watchers. The event mask is named after the 331 same callback for multiple watchers. The event mask is named after the
139 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 332 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
140 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 333 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
141 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 334 events (which can set both EV::READ and EV::WRITE bits).
142 (which uses EV::TIMEOUT).
143 335
144 In the rare case where one wants to create a watcher but not start it at 336 In the rare case where one wants to create a watcher but not start it at
145 the same time, each constructor has a variant with a trailing "_ns" in 337 the same time, each constructor has a variant with a trailing "_ns" in
146 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 338 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
147 339
… …
163 stopped watchers). 355 stopped watchers).
164 356
165 $w->stop 357 $w->stop
166 Stop a watcher if it is active. Also clear any pending events 358 Stop a watcher if it is active. Also clear any pending events
167 (events that have been received but that didn't yet result in a 359 (events that have been received but that didn't yet result in a
168 callback invocation), regardless of wether the watcher was active or 360 callback invocation), regardless of whether the watcher was active
169 not. 361 or not.
170 362
171 $bool = $w->is_active 363 $bool = $w->is_active
172 Returns true if the watcher is active, false otherwise. 364 Returns true if the watcher is active, false otherwise.
173 365
174 $current_data = $w->data 366 $current_data = $w->data
… …
197 The default priority of any newly-created watcher is 0. 389 The default priority of any newly-created watcher is 0.
198 390
199 Note that the priority semantics have not yet been fleshed out and 391 Note that the priority semantics have not yet been fleshed out and
200 are subject to almost certain change. 392 are subject to almost certain change.
201 393
202 $w->trigger ($revents) 394 $w->invoke ($revents)
203 Call the callback *now* with the given event mask. 395 Call the callback *now* with the given event mask.
396
397 $w->feed_event ($revents)
398 Feed some events on this watcher into EV. EV will react to this call
399 as if the watcher had received the given $revents mask.
400
401 $revents = $w->clear_pending
402 If the watcher is pending, this function clears its pending status
403 and returns its $revents bitset (as if its callback was invoked). If
404 the watcher isn't pending it does nothing and returns 0.
204 405
205 $previous_state = $w->keepalive ($bool) 406 $previous_state = $w->keepalive ($bool)
206 Normally, "EV::loop" will return when there are no active watchers 407 Normally, "EV::loop" will return when there are no active watchers
207 (which is a "deadlock" because no progress can be made anymore). 408 (which is a "deadlock" because no progress can be made anymore).
208 This is convinient because it allows you to start your watchers (and 409 This is convenient because it allows you to start your watchers (and
209 your jobs), call "EV::loop" once and when it returns you know that 410 your jobs), call "EV::loop" once and when it returns you know that
210 all your jobs are finished (or they forgot to register some watchers 411 all your jobs are finished (or they forgot to register some watchers
211 for their task :). 412 for their task :).
212 413
213 Sometimes, however, this gets in your way, for example when you the 414 Sometimes, however, this gets in your way, for example when the
214 module that calls "EV::loop" (usually the main program) is not the 415 module that calls "EV::loop" (usually the main program) is not the
215 same module as a long-living watcher (for example a DNS client 416 same module as a long-living watcher (for example a DNS client
216 module written by somebody else even). Then you might want any 417 module written by somebody else even). Then you might want any
217 outstanding requests to be handled, but you would not want to keep 418 outstanding requests to be handled, but you would not want to keep
218 "EV::loop" from returning just because you happen to have this 419 "EV::loop" from returning just because you happen to have this
… …
220 421
221 In this case you can clear the keepalive status, which means that 422 In this case you can clear the keepalive status, which means that
222 even though your watcher is active, it won't keep "EV::loop" from 423 even though your watcher is active, it won't keep "EV::loop" from
223 returning. 424 returning.
224 425
225 The initial value for keepalive is true (enabled), and you cna 426 The initial value for keepalive is true (enabled), and you can
226 change it any time. 427 change it any time.
227 428
228 Example: Register an IO watcher for some UDP socket but do not keep 429 Example: Register an I/O watcher for some UDP socket but do not keep
229 the event loop from running just because of that watcher. 430 the event loop from running just because of that watcher.
230 431
231 my $udp_socket = ... 432 my $udp_socket = ...
232 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 433 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
233 $udp_watcher->keepalive (0); 434 $udp_watcher->keepalive (0);
234 435
436 $loop = $w->loop
437 Return the loop that this watcher is attached to.
438
235 WATCHER TYPES 439WATCHER TYPES
236 Each of the following subsections describes a single watcher type. 440 Each of the following subsections describes a single watcher type.
237 441
238 IO WATCHERS - is this file descriptor readable or writable? 442 I/O WATCHERS - is this file descriptor readable or writable?
239 $w = EV::io $fileno_or_fh, $eventmask, $callback 443 $w = EV::io $fileno_or_fh, $eventmask, $callback
240 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 444 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
445 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
446 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
241 As long as the returned watcher object is alive, call the $callback 447 As long as the returned watcher object is alive, call the $callback
242 when at least one of events specified in $eventmask occurs. 448 when at least one of events specified in $eventmask occurs.
243 449
244 The $eventmask can be one or more of these constants ORed together: 450 The $eventmask can be one or more of these constants ORed together:
245 451
… …
262 Returns the previously set event mask and optionally set a new one. 468 Returns the previously set event mask and optionally set a new one.
263 469
264 TIMER WATCHERS - relative and optionally repeating timeouts 470 TIMER WATCHERS - relative and optionally repeating timeouts
265 $w = EV::timer $after, $repeat, $callback 471 $w = EV::timer $after, $repeat, $callback
266 $w = EV::timer_ns $after, $repeat, $callback 472 $w = EV::timer_ns $after, $repeat, $callback
473 $w = $loop->timer ($after, $repeat, $callback)
474 $w = $loop->timer_ns ($after, $repeat, $callback)
267 Calls the callback after $after seconds (which may be fractional). 475 Calls the callback after $after seconds (which may be fractional).
268 If $repeat is non-zero, the timer will be restarted (with the 476 If $repeat is non-zero, the timer will be restarted (with the
269 $repeat value as $after) after the callback returns. 477 $repeat value as $after) after the callback returns.
270 478
271 This means that the callback would be called roughly after $after 479 This means that the callback would be called roughly after $after
… …
307 method on the timeout. 515 method on the timeout.
308 516
309 PERIODIC WATCHERS - to cron or not to cron? 517 PERIODIC WATCHERS - to cron or not to cron?
310 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 518 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
311 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 519 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
520 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
521 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
312 Similar to EV::timer, but is not based on relative timeouts but on 522 Similar to EV::timer, but is not based on relative timeouts but on
313 absolute times. Apart from creating "simple" timers that trigger 523 absolute times. Apart from creating "simple" timers that trigger
314 "at" the specified time, it can also be used for non-drifting 524 "at" the specified time, it can also be used for non-drifting
315 absolute timers and more complex, cron-like, setups that are not 525 absolute timers and more complex, cron-like, setups that are not
316 adversely affected by time jumps (i.e. when the system clock is 526 adversely affected by time jumps (i.e. when the system clock is
317 changed by explicit date -s or other means such as ntpd). It is also 527 changed by explicit date -s or other means such as ntpd). It is also
318 the most complex watcher type in EV. 528 the most complex watcher type in EV.
319 529
320 It has three distinct "modes": 530 It has three distinct "modes":
321 531
322 * absolute timer ($interval = $reschedule_cb = 0) 532 * absolute timer ($interval = $reschedule_cb = 0)
533
323 This time simply fires at the wallclock time $at and doesn't 534 This time simply fires at the wallclock time $at and doesn't
324 repeat. It will not adjust when a time jump occurs, that is, if 535 repeat. It will not adjust when a time jump occurs, that is, if
325 it is to be run at January 1st 2011 then it will run when the 536 it is to be run at January 1st 2011 then it will run when the
326 system time reaches or surpasses this time. 537 system time reaches or surpasses this time.
327 538
328 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 539 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
540
329 In this mode the watcher will always be scheduled to time out at 541 In this mode the watcher will always be scheduled to time out at
330 the next "$at + N * $interval" time (for some integer N) and 542 the next "$at + N * $interval" time (for some integer N) and
331 then repeat, regardless of any time jumps. 543 then repeat, regardless of any time jumps.
332 544
333 This can be used to create timers that do not drift with respect 545 This can be used to create timers that do not drift with respect
… …
342 Another way to think about it (for the mathematically inclined) 554 Another way to think about it (for the mathematically inclined)
343 is that EV::periodic will try to run the callback in this mode 555 is that EV::periodic will try to run the callback in this mode
344 at the next possible time where "$time = $at (mod $interval)", 556 at the next possible time where "$time = $at (mod $interval)",
345 regardless of any time jumps. 557 regardless of any time jumps.
346 558
347 * manual reschedule mode ($reschedule_cb = coderef) 559 * manual reschedule mode ($reschedule_cb = coderef)
560
348 In this mode $interval and $at are both being ignored. Instead, 561 In this mode $interval and $at are both being ignored. Instead,
349 each time the periodic watcher gets scheduled, the reschedule 562 each time the periodic watcher gets scheduled, the reschedule
350 callback ($reschedule_cb) will be called with the watcher as 563 callback ($reschedule_cb) will be called with the watcher as
351 first, and the current time as second argument. 564 first, and the current time as second argument.
352 565
353 *This callback MUST NOT stop or destroy this or any other 566 *This callback MUST NOT stop or destroy this or any other
567 periodic watcher, ever, and MUST NOT call any event loop
354 periodic watcher, ever*. If you need to stop it, return 1e30 and 568 functions or methods*. If you need to stop it, return 1e30 and
355 stop it afterwards. 569 stop it afterwards. You may create and start a "EV::prepare"
570 watcher for this task.
356 571
357 It must return the next time to trigger, based on the passed 572 It must return the next time to trigger, based on the passed
358 time value (that is, the lowest time value larger than to the 573 time value (that is, the lowest time value larger than or equal
359 second argument). It will usually be called just before the 574 to to the second argument). It will usually be called just
360 callback will be triggered, but might be called at other times, 575 before the callback will be triggered, but might be called at
361 too. 576 other times, too.
362 577
363 This can be used to create very complex timers, such as a timer 578 This can be used to create very complex timers, such as a timer
364 that triggers on each midnight, local time (actually 24 hours 579 that triggers on each midnight, local time (actually 24 hours
365 after the last midnight, to keep the example simple. If you know 580 after the last midnight, to keep the example simple. If you know
366 a way to do it correctly in about the same space (without 581 a way to do it correctly in about the same space (without
… …
384 be called at any time. 599 be called at any time.
385 600
386 $w->again 601 $w->again
387 Simply stops and starts the watcher again. 602 Simply stops and starts the watcher again.
388 603
604 $time = $w->at
605 Return the time that the watcher is expected to trigger next.
606
389 SIGNAL WATCHERS - signal me when a signal gets signalled! 607 SIGNAL WATCHERS - signal me when a signal gets signalled!
390 $w = EV::signal $signal, $callback 608 $w = EV::signal $signal, $callback
391 $w = EV::signal_ns $signal, $callback 609 $w = EV::signal_ns $signal, $callback
610 $w = $loop->signal ($signal, $callback)
611 $w = $loop->signal_ns ($signal, $callback)
392 Call the callback when $signal is received (the signal can be 612 Call the callback when $signal is received (the signal can be
393 specified by number or by name, just as with "kill" or %SIG). 613 specified by number or by name, just as with "kill" or %SIG).
614
615 Only one event loop can grab a given signal - attempting to grab the
616 same signal from two EV loops will crash the program immediately or
617 cause data corruption.
394 618
395 EV will grab the signal for the process (the kernel only allows one 619 EV will grab the signal for the process (the kernel only allows one
396 component to receive a signal at a time) when you start a signal 620 component to receive a signal at a time) when you start a signal
397 watcher, and removes it again when you stop it. Perl does the same 621 watcher, and removes it again when you stop it. Perl does the same
398 when you add/remove callbacks to %SIG, so watch out. 622 when you add/remove callbacks to %SIG, so watch out.
… …
410 $old_signum = $w->signal ($new_signal) 634 $old_signum = $w->signal ($new_signal)
411 Returns the previously set signal (always as a number not name) and 635 Returns the previously set signal (always as a number not name) and
412 optionally set a new one. 636 optionally set a new one.
413 637
414 CHILD WATCHERS - watch out for process status changes 638 CHILD WATCHERS - watch out for process status changes
415 $w = EV::child $pid, $callback 639 $w = EV::child $pid, $trace, $callback
416 $w = EV::child_ns $pid, $callback 640 $w = EV::child_ns $pid, $trace, $callback
641 $w = $loop->child ($pid, $trace, $callback)
642 $w = $loop->child_ns ($pid, $trace, $callback)
417 Call the callback when a status change for pid $pid (or any pid if 643 Call the callback when a status change for pid $pid (or any pid if
418 $pid is 0) has been received. More precisely: when the process 644 $pid is 0) has been received (a status change happens when the
645 process terminates or is killed, or, when trace is true,
646 additionally when it is stopped or continued). More precisely: when
419 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 647 the process receives a "SIGCHLD", EV will fetch the outstanding
420 for all changed/zombie children and call the callback. 648 exit/wait status for all changed/zombie children and call the
649 callback.
421 650
422 It is valid (and fully supported) to install a child watcher after a 651 It is valid (and fully supported) to install a child watcher after a
423 child has exited but before the event loop has started its next 652 child has exited but before the event loop has started its next
424 iteration (for example, first you "fork", then the new child process 653 iteration (for example, first you "fork", then the new child process
425 might exit, and only then do you install a child watcher in the 654 might exit, and only then do you install a child watcher in the
… …
432 be called. 661 be called.
433 662
434 The "child_ns" variant doesn't start (activate) the newly created 663 The "child_ns" variant doesn't start (activate) the newly created
435 watcher. 664 watcher.
436 665
437 $w->set ($pid) 666 $w->set ($pid, $trace)
438 Reconfigures the watcher, see the constructor above for details. Can 667 Reconfigures the watcher, see the constructor above for details. Can
439 be called at any time. 668 be called at any time.
440 669
441 $current_pid = $w->pid 670 $current_pid = $w->pid
442 $old_pid = $w->pid ($new_pid)
443 Returns the previously set process id and optionally set a new one. 671 Returns the previously set process id and optionally set a new one.
444 672
445 $exit_status = $w->rstatus 673 $exit_status = $w->rstatus
446 Return the exit/wait status (as returned by waitpid, see the waitpid 674 Return the exit/wait status (as returned by waitpid, see the waitpid
447 entry in perlfunc). 675 entry in perlfunc).
… …
451 a watcher for all pids). 679 a watcher for all pids).
452 680
453 STAT WATCHERS - did the file attributes just change? 681 STAT WATCHERS - did the file attributes just change?
454 $w = EV::stat $path, $interval, $callback 682 $w = EV::stat $path, $interval, $callback
455 $w = EV::stat_ns $path, $interval, $callback 683 $w = EV::stat_ns $path, $interval, $callback
684 $w = $loop->stat ($path, $interval, $callback)
685 $w = $loop->stat_ns ($path, $interval, $callback)
456 Call the callback when a file status change has been detected on 686 Call the callback when a file status change has been detected on
457 $path. The $path does not need to exist, changing from "path exists" 687 $path. The $path does not need to exist, changing from "path exists"
458 to "path does not exist" is a status change like any other. 688 to "path does not exist" is a status change like any other.
459 689
460 The $interval is a recommended polling interval for systems where 690 The $interval is a recommended polling interval for systems where
… …
520 Can be used to query the actual interval used. 750 Can be used to query the actual interval used.
521 751
522 IDLE WATCHERS - when you've got nothing better to do... 752 IDLE WATCHERS - when you've got nothing better to do...
523 $w = EV::idle $callback 753 $w = EV::idle $callback
524 $w = EV::idle_ns $callback 754 $w = EV::idle_ns $callback
755 $w = $loop->idle ($callback)
756 $w = $loop->idle_ns ($callback)
525 Call the callback when there are no pending io, timer/periodic, 757 Call the callback when there are no other pending watchers of the
526 signal or child events, i.e. when the process is idle. 758 same or higher priority (excluding check, prepare and other idle
759 watchers of the same or lower priority, of course). They are called
760 idle watchers because when the watcher is the highest priority
761 pending event in the process, the process is considered to be idle
762 at that priority.
763
764 If you want a watcher that is only ever called when *no* other
765 events are outstanding you have to set the priority to "EV::MINPRI".
527 766
528 The process will not block as long as any idle watchers are active, 767 The process will not block as long as any idle watchers are active,
529 and they will be called repeatedly until stopped. 768 and they will be called repeatedly until stopped.
769
770 For example, if you have idle watchers at priority 0 and 1, and an
771 I/O watcher at priority 0, then the idle watcher at priority 1 and
772 the I/O watcher will always run when ready. Only when the idle
773 watcher at priority 1 is stopped and the I/O watcher at priority 0
774 is not pending with the 0-priority idle watcher be invoked.
530 775
531 The "idle_ns" variant doesn't start (activate) the newly created 776 The "idle_ns" variant doesn't start (activate) the newly created
532 watcher. 777 watcher.
533 778
534 PREPARE WATCHERS - customise your event loop! 779 PREPARE WATCHERS - customise your event loop!
535 $w = EV::prepare $callback 780 $w = EV::prepare $callback
536 $w = EV::prepare_ns $callback 781 $w = EV::prepare_ns $callback
782 $w = $loop->prepare ($callback)
783 $w = $loop->prepare_ns ($callback)
537 Call the callback just before the process would block. You can still 784 Call the callback just before the process would block. You can still
538 create/modify any watchers at this point. 785 create/modify any watchers at this point.
539 786
540 See the EV::check watcher, below, for explanations and an example. 787 See the EV::check watcher, below, for explanations and an example.
541 788
… …
543 watcher. 790 watcher.
544 791
545 CHECK WATCHERS - customise your event loop even more! 792 CHECK WATCHERS - customise your event loop even more!
546 $w = EV::check $callback 793 $w = EV::check $callback
547 $w = EV::check_ns $callback 794 $w = EV::check_ns $callback
795 $w = $loop->check ($callback)
796 $w = $loop->check_ns ($callback)
548 Call the callback just after the process wakes up again (after it 797 Call the callback just after the process wakes up again (after it
549 has gathered events), but before any other callbacks have been 798 has gathered events), but before any other callbacks have been
550 invoked. 799 invoked.
551 800
552 This is used to integrate other event-based software into the EV 801 This can be used to integrate other event-based software into the EV
553 mainloop: You register a prepare callback and in there, you create 802 mainloop: You register a prepare callback and in there, you create
554 io and timer watchers as required by the other software. Here is a 803 io and timer watchers as required by the other software. Here is a
555 real-world example of integrating Net::SNMP (with some details left 804 real-world example of integrating Net::SNMP (with some details left
556 out): 805 out):
557 806
… …
563 or return; 812 or return;
564 813
565 # make the dispatcher handle any outstanding stuff 814 # make the dispatcher handle any outstanding stuff
566 ... not shown 815 ... not shown
567 816
568 # create an IO watcher for each and every socket 817 # create an I/O watcher for each and every socket
569 @snmp_watcher = ( 818 @snmp_watcher = (
570 (map { EV::io $_, EV::READ, sub { } } 819 (map { EV::io $_, EV::READ, sub { } }
571 keys %{ $dispatcher->{_descriptors} }), 820 keys %{ $dispatcher->{_descriptors} }),
572 821
573 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 822 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
… …
588 # make the dispatcher handle any new stuff 837 # make the dispatcher handle any new stuff
589 ... not shown 838 ... not shown
590 }; 839 };
591 840
592 The callbacks of the created watchers will not be called as the 841 The callbacks of the created watchers will not be called as the
593 watchers are destroyed before this cna happen (remember EV::check 842 watchers are destroyed before this can happen (remember EV::check
594 gets called first). 843 gets called first).
595 844
596 The "check_ns" variant doesn't start (activate) the newly created 845 The "check_ns" variant doesn't start (activate) the newly created
597 watcher. 846 watcher.
847
848 EV::CHECK constant issues
849 Like all other watcher types, there is a bitmask constant for use in
850 $revents and other places. The "EV::CHECK" is special as it has the
851 same name as the "CHECK" sub called by Perl. This doesn't cause big
852 issues on newer perls (beginning with 5.8.9), but it means thatthe
853 constant must be *inlined*, i.e. runtime calls will not work. That
854 means that as long as you always "use EV" and then "EV::CHECK" you
855 are on the safe side.
598 856
599 FORK WATCHERS - the audacity to resume the event loop after a fork 857 FORK WATCHERS - the audacity to resume the event loop after a fork
600 Fork watchers are called when a "fork ()" was detected. The invocation 858 Fork watchers are called when a "fork ()" was detected. The invocation
601 is done before the event loop blocks next and before "check" watchers 859 is done before the event loop blocks next and before "check" watchers
602 are being called, and only in the child after the fork. 860 are being called, and only in the child after the fork.
603 861
604 $w = EV::fork $callback 862 $w = EV::fork $callback
605 $w = EV::fork_ns $callback 863 $w = EV::fork_ns $callback
864 $w = $loop->fork ($callback)
865 $w = $loop->fork_ns ($callback)
606 Call the callback before the event loop is resumed in the child 866 Call the callback before the event loop is resumed in the child
607 process after a fork. 867 process after a fork.
608 868
609 The "fork_ns" variant doesn't start (activate) the newly created 869 The "fork_ns" variant doesn't start (activate) the newly created
610 watcher. 870 watcher.
611 871
872 EMBED WATCHERS - when one backend isn't enough...
873 This is a rather advanced watcher type that lets you embed one event
874 loop into another (currently only IO events are supported in the
875 embedded loop, other types of watchers might be handled in a delayed or
876 incorrect fashion and must not be used).
877
878 See the libev documentation at
879 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
880 _when_one_backend_> (locally installed as EV::libev) for more details.
881
882 In short, this watcher is most useful on BSD systems without working
883 kqueue to still be able to handle a large number of sockets:
884
885 my $socket_loop;
886
887 # check wether we use SELECT or POLL _and_ KQUEUE is supported
888 if (
889 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
890 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
891 ) {
892 # use kqueue for sockets
893 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
894 }
895
896 # use the default loop otherwise
897 $socket_loop ||= EV::default_loop;
898
899 $w = EV::embed $otherloop[, $callback]
900 $w = EV::embed_ns $otherloop[, $callback]
901 $w = $loop->embed ($otherloop[, $callback])
902 $w = $loop->embed_ns ($otherloop[, $callback])
903 Call the callback when the embedded event loop ($otherloop) has any
904 I/O activity. The $callback is optional: if it is missing, then the
905 embedded event loop will be managed automatically (which is
906 recommended), otherwise you have to invoke "sweep" yourself.
907
908 The "embed_ns" variant doesn't start (activate) the newly created
909 watcher.
910
911 ASYNC WATCHERS - how to wake up another event loop
912 Async watchers are provided by EV, but have little use in perl directly,
913 as perl neither supports threads running in parallel nor direct access
914 to signal handlers or other contexts where they could be of value.
915
916 It is, however, possible to use them from the XS level.
917
918 Please see the libev documentation for further details.
919
920 $w = EV::async $callback
921 $w = EV::async_ns $callback
922 $w->send
923 $bool = $w->async_pending
924
925PERL SIGNALS
926 While Perl signal handling (%SIG) is not affected by EV, the behaviour
927 with EV is as the same as any other C library: Perl-signals will only be
928 handled when Perl runs, which means your signal handler might be invoked
929 only the next time an event callback is invoked.
930
931 The solution is to use EV signal watchers (see "EV::signal"), which will
932 ensure proper operations with regards to other event watchers.
933
934 If you cannot do this for whatever reason, you can also force a watcher
935 to be called on every event loop iteration by installing a "EV::check"
936 watcher:
937
938 my $async_check = EV::check sub { };
939
940 This ensures that perl gets into control for a short time to handle any
941 pending signals, and also ensures (slightly) slower overall operation.
942
612THREADS 943ITHREADS
613 Threads are not supported by this module in any way. Perl pseudo-threads 944 Ithreads are not supported by this module in any way. Perl
614 is evil stuff and must die. As soon as Perl gains real threads I will 945 pseudo-threads is evil stuff and must die. Real threads as provided by
615 work on thread support for it. 946 Coro are fully supported (and enhanced support is available via
947 Coro::EV).
616 948
617FORK 949FORK
618 Most of the "improved" event delivering mechanisms of modern operating 950 Most of the "improved" event delivering mechanisms of modern operating
619 systems have quite a few problems with fork(2) (to put it bluntly: it is 951 systems have quite a few problems with fork(2) (to put it bluntly: it is
620 not supported and usually destructive). Libev makes it possible to work 952 not supported and usually destructive). Libev makes it possible to work
… …
630 962
631 On win32, there is no notion of fork so all this doesn't apply, of 963 On win32, there is no notion of fork so all this doesn't apply, of
632 course. 964 course.
633 965
634SEE ALSO 966SEE ALSO
635 EV::DNS. 967 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
968 DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed
969 Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV
970 (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event
971 driven programming.
636 972
637AUTHOR 973AUTHOR
638 Marc Lehmann <schmorp@schmorp.de> 974 Marc Lehmann <schmorp@schmorp.de>
639 http://home.schmorp.de/ 975 http://home.schmorp.de/
640 976

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