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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", or just 70 discussion on the available backends, or how to force a specific backend
62 about in any case because it has much more detailed information. 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.
63 167
64BASIC INTERFACE 168BASIC INTERFACE
65 $EV::DIED 169 $EV::DIED
66 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
67 callback throws an exception (with $@ containing thr error). The 171 callback throws an exception (with $@ containing the error). The
68 default prints an informative message and continues. 172 default prints an informative message and continues.
69 173
70 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.
71 186
72 $time = EV::time 187 $time = EV::time
73 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
74 189
75 $time = EV::now 190 $time = EV::now
191 $time = $loop->now
76 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
77 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
78 to it is usually faster then calling EV::time. 194 to it is usually faster then calling EV::time.
79 195
80 $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 = $loop->backend
81 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
82 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
83 237
84 EV::loop [$flags] 238 EV::loop [$flags]
239 $loop->loop ([$flags])
85 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
86 callback calls EV::unloop. 241 callback calls EV::unloop.
87 242
88 The $flags argument can be one of the following: 243 The $flags argument can be one of the following:
89 244
90 0 as above 245 0 as above
91 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 246 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
92 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 247 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
93 248
94 EV::unloop [$how] 249 EV::unloop [$how]
250 $loop->unloop ([$how])
95 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,
96 makes the innermost call to EV::loop return. 252 makes the innermost call to EV::loop return.
97 253
98 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
99 EV::loop will return as fast as possible. 255 EV::loop will return as fast as possible.
100 256
101 $count = EV::loop_count 257 $count = EV::loop_count
258 $count = $loop->loop_count
102 Return the number of times the event loop has polled for new events. 259 Return the number of times the event loop has polled for new events.
103 Sometiems useful as a generation counter. 260 Sometimes useful as a generation counter.
104 261
105 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))
106 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
107 one-shot event without the need for managing a watcher object. 265 one-shot event without the need for managing a watcher object.
108 266
109 If $fh_or_undef is a filehandle or file descriptor, then $events 267 If $fh_or_undef is a filehandle or file descriptor, then $events
110 must be a bitset containing either "EV::READ", "EV::WRITE" or 268 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
115 If timeout is "undef" or negative, then there will be no timeout. 273 If timeout is "undef" or negative, then there will be no timeout.
116 Otherwise a EV::timer with this value will be started. 274 Otherwise a EV::timer with this value will be started.
117 275
118 When an error occurs or either the timeout or I/O watcher triggers, 276 When an error occurs or either the timeout or I/O watcher triggers,
119 then the callback will be called with the received event set (in 277 then the callback will be called with the received event set (in
120 general you can expect it to be a combination of "EV:ERROR", 278 general you can expect it to be a combination of "EV::ERROR",
121 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 279 "EV::READ", "EV::WRITE" and "EV::TIMER").
122 280
123 EV::once doesn't return anything: the watchers stay active till 281 EV::once doesn't return anything: the watchers stay active till
124 either of them triggers, then they will be stopped and freed, and 282 either of them triggers, then they will be stopped and freed, and
125 the callback invoked. 283 the callback invoked.
126 284
285 EV::feed_fd_event ($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
127 WATCHER OBJECTS 315WATCHER OBJECTS
128 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
129 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,
130 you would create an EV::io watcher for that: 318 you would create an EV::io watcher for that:
131 319
132 my $watcher = EV::io *STDIN, EV::READ, sub { 320 my $watcher = EV::io *STDIN, EV::READ, sub {
133 my ($watcher, $revents) = @_; 321 my ($watcher, $revents) = @_;
134 warn "yeah, STDIN should not be readable without blocking!\n" 322 warn "yeah, STDIN should now be readable without blocking!\n"
135 }; 323 };
136 324
137 All watchers can be active (waiting for events) or inactive (paused). 325 All watchers can be active (waiting for events) or inactive (paused).
138 Only active watchers will have their callbacks invoked. All callbacks 326 Only active watchers will have their callbacks invoked. All callbacks
139 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
140 received events. 328 received events.
141 329
142 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
143 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
144 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,
145 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O 333 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
146 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).
147 (which uses EV::TIMEOUT).
148 335
149 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
150 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
151 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.
152 339
… …
202 The default priority of any newly-created watcher is 0. 389 The default priority of any newly-created watcher is 0.
203 390
204 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
205 are subject to almost certain change. 392 are subject to almost certain change.
206 393
207 $w->trigger ($revents) 394 $w->invoke ($revents)
208 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.
209 405
210 $previous_state = $w->keepalive ($bool) 406 $previous_state = $w->keepalive ($bool)
211 Normally, "EV::loop" will return when there are no active watchers 407 Normally, "EV::loop" will return when there are no active watchers
212 (which is a "deadlock" because no progress can be made anymore). 408 (which is a "deadlock" because no progress can be made anymore).
213 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
214 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
215 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
216 for their task :). 412 for their task :).
217 413
218 Sometimes, however, this gets in your way, for example when you the 414 Sometimes, however, this gets in your way, for example when the
219 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
220 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
221 module written by somebody else even). Then you might want any 417 module written by somebody else even). Then you might want any
222 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
223 "EV::loop" from returning just because you happen to have this 419 "EV::loop" from returning just because you happen to have this
… …
225 421
226 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
227 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
228 returning. 424 returning.
229 425
230 The initial value for keepalive is true (enabled), and you cna 426 The initial value for keepalive is true (enabled), and you can
231 change it any time. 427 change it any time.
232 428
233 Example: Register an I/O watcher for some UDP socket but do not keep 429 Example: Register an I/O watcher for some UDP socket but do not keep
234 the event loop from running just because of that watcher. 430 the event loop from running just because of that watcher.
235 431
236 my $udp_socket = ... 432 my $udp_socket = ...
237 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 433 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
238 $udp_watcher->keepalive (0); 434 $udp_watcher->keepalive (0);
239 435
436 $loop = $w->loop
437 Return the loop that this watcher is attached to.
438
240 WATCHER TYPES 439WATCHER TYPES
241 Each of the following subsections describes a single watcher type. 440 Each of the following subsections describes a single watcher type.
242 441
243 I/O WATCHERS - is this file descriptor readable or writable? 442 I/O WATCHERS - is this file descriptor readable or writable?
244 $w = EV::io $fileno_or_fh, $eventmask, $callback 443 $w = EV::io $fileno_or_fh, $eventmask, $callback
245 $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)
246 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
247 when at least one of events specified in $eventmask occurs. 448 when at least one of events specified in $eventmask occurs.
248 449
249 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:
250 451
… …
267 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.
268 469
269 TIMER WATCHERS - relative and optionally repeating timeouts 470 TIMER WATCHERS - relative and optionally repeating timeouts
270 $w = EV::timer $after, $repeat, $callback 471 $w = EV::timer $after, $repeat, $callback
271 $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)
272 Calls the callback after $after seconds (which may be fractional). 475 Calls the callback after $after seconds (which may be fractional).
273 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
274 $repeat value as $after) after the callback returns. 477 $repeat value as $after) after the callback returns.
275 478
276 This means that the callback would be called roughly after $after 479 This means that the callback would be called roughly after $after
… …
312 method on the timeout. 515 method on the timeout.
313 516
314 PERIODIC WATCHERS - to cron or not to cron? 517 PERIODIC WATCHERS - to cron or not to cron?
315 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 518 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
316 $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, $callback)
317 Similar to EV::timer, but is not based on relative timeouts but on 522 Similar to EV::timer, but is not based on relative timeouts but on
318 absolute times. Apart from creating "simple" timers that trigger 523 absolute times. Apart from creating "simple" timers that trigger
319 "at" the specified time, it can also be used for non-drifting 524 "at" the specified time, it can also be used for non-drifting
320 absolute timers and more complex, cron-like, setups that are not 525 absolute timers and more complex, cron-like, setups that are not
321 adversely affected by time jumps (i.e. when the system clock is 526 adversely affected by time jumps (i.e. when the system clock is
322 changed by explicit date -s or other means such as ntpd). It is also 527 changed by explicit date -s or other means such as ntpd). It is also
323 the most complex watcher type in EV. 528 the most complex watcher type in EV.
324 529
325 It has three distinct "modes": 530 It has three distinct "modes":
326 531
327 * absolute timer ($interval = $reschedule_cb = 0) 532 * absolute timer ($interval = $reschedule_cb = 0)
533
328 This time simply fires at the wallclock time $at and doesn't 534 This time simply fires at the wallclock time $at and doesn't
329 repeat. It will not adjust when a time jump occurs, that is, if 535 repeat. It will not adjust when a time jump occurs, that is, if
330 it is to be run at January 1st 2011 then it will run when the 536 it is to be run at January 1st 2011 then it will run when the
331 system time reaches or surpasses this time. 537 system time reaches or surpasses this time.
332 538
333 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 539 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
540
334 In this mode the watcher will always be scheduled to time out at 541 In this mode the watcher will always be scheduled to time out at
335 the next "$at + N * $interval" time (for some integer N) and 542 the next "$at + N * $interval" time (for some integer N) and
336 then repeat, regardless of any time jumps. 543 then repeat, regardless of any time jumps.
337 544
338 This can be used to create timers that do not drift with respect 545 This can be used to create timers that do not drift with respect
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347 Another way to think about it (for the mathematically inclined) 554 Another way to think about it (for the mathematically inclined)
348 is that EV::periodic will try to run the callback in this mode 555 is that EV::periodic will try to run the callback in this mode
349 at the next possible time where "$time = $at (mod $interval)", 556 at the next possible time where "$time = $at (mod $interval)",
350 regardless of any time jumps. 557 regardless of any time jumps.
351 558
352 * manual reschedule mode ($reschedule_cb = coderef) 559 * manual reschedule mode ($reschedule_cb = coderef)
560
353 In this mode $interval and $at are both being ignored. Instead, 561 In this mode $interval and $at are both being ignored. Instead,
354 each time the periodic watcher gets scheduled, the reschedule 562 each time the periodic watcher gets scheduled, the reschedule
355 callback ($reschedule_cb) will be called with the watcher as 563 callback ($reschedule_cb) will be called with the watcher as
356 first, and the current time as second argument. 564 first, and the current time as second argument.
357 565
358 *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
359 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
360 stop it afterwards. 569 stop it afterwards. You may create and start a "EV::prepare"
570 watcher for this task.
361 571
362 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
363 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
364 second argument). It will usually be called just before the 574 to to the second argument). It will usually be called just
365 callback will be triggered, but might be called at other times, 575 before the callback will be triggered, but might be called at
366 too. 576 other times, too.
367 577
368 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
369 that triggers on each midnight, local time (actually 24 hours 579 that triggers on each midnight, local time (actually 24 hours
370 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
371 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
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389 be called at any time. 599 be called at any time.
390 600
391 $w->again 601 $w->again
392 Simply stops and starts the watcher again. 602 Simply stops and starts the watcher again.
393 603
604 $time = $w->at
605 Return the time that the watcher is expected to trigger next.
606
394 SIGNAL WATCHERS - signal me when a signal gets signalled! 607 SIGNAL WATCHERS - signal me when a signal gets signalled!
395 $w = EV::signal $signal, $callback 608 $w = EV::signal $signal, $callback
396 $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)
397 Call the callback when $signal is received (the signal can be 612 Call the callback when $signal is received (the signal can be
398 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.
399 618
400 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
401 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
402 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
403 when you add/remove callbacks to %SIG, so watch out. 622 when you add/remove callbacks to %SIG, so watch out.
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415 $old_signum = $w->signal ($new_signal) 634 $old_signum = $w->signal ($new_signal)
416 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
417 optionally set a new one. 636 optionally set a new one.
418 637
419 CHILD WATCHERS - watch out for process status changes 638 CHILD WATCHERS - watch out for process status changes
420 $w = EV::child $pid, $callback 639 $w = EV::child $pid, $trace, $callback
421 $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)
422 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
423 $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
424 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 647 the process receives a "SIGCHLD", EV will fetch the outstanding
425 for all changed/zombie children and call the callback. 648 exit/wait status for all changed/zombie children and call the
649 callback.
426 650
427 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
428 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
429 iteration (for example, first you "fork", then the new child process 653 iteration (for example, first you "fork", then the new child process
430 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
… …
437 be called. 661 be called.
438 662
439 The "child_ns" variant doesn't start (activate) the newly created 663 The "child_ns" variant doesn't start (activate) the newly created
440 watcher. 664 watcher.
441 665
442 $w->set ($pid) 666 $w->set ($pid, $trace)
443 Reconfigures the watcher, see the constructor above for details. Can 667 Reconfigures the watcher, see the constructor above for details. Can
444 be called at any time. 668 be called at any time.
445 669
446 $current_pid = $w->pid 670 $current_pid = $w->pid
447 $old_pid = $w->pid ($new_pid)
448 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.
449 672
450 $exit_status = $w->rstatus 673 $exit_status = $w->rstatus
451 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
452 entry in perlfunc). 675 entry in perlfunc).
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456 a watcher for all pids). 679 a watcher for all pids).
457 680
458 STAT WATCHERS - did the file attributes just change? 681 STAT WATCHERS - did the file attributes just change?
459 $w = EV::stat $path, $interval, $callback 682 $w = EV::stat $path, $interval, $callback
460 $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)
461 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
462 $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"
463 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.
464 689
465 The $interval is a recommended polling interval for systems where 690 The $interval is a recommended polling interval for systems where
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525 Can be used to query the actual interval used. 750 Can be used to query the actual interval used.
526 751
527 IDLE WATCHERS - when you've got nothing better to do... 752 IDLE WATCHERS - when you've got nothing better to do...
528 $w = EV::idle $callback 753 $w = EV::idle $callback
529 $w = EV::idle_ns $callback 754 $w = EV::idle_ns $callback
755 $w = $loop->idle ($callback)
756 $w = $loop->idle_ns ($callback)
530 Call the callback when there are no other pending watchers of the 757 Call the callback when there are no other pending watchers of the
531 same or higher priority (excluding check, prepare and other idle 758 same or higher priority (excluding check, prepare and other idle
532 watchers of the same or lower priority, of course). They are called 759 watchers of the same or lower priority, of course). They are called
533 idle watchers because when the watcher is the highest priority 760 idle watchers because when the watcher is the highest priority
534 pending event in the process, the process is considered to be idle 761 pending event in the process, the process is considered to be idle
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550 watcher. 777 watcher.
551 778
552 PREPARE WATCHERS - customise your event loop! 779 PREPARE WATCHERS - customise your event loop!
553 $w = EV::prepare $callback 780 $w = EV::prepare $callback
554 $w = EV::prepare_ns $callback 781 $w = EV::prepare_ns $callback
782 $w = $loop->prepare ($callback)
783 $w = $loop->prepare_ns ($callback)
555 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
556 create/modify any watchers at this point. 785 create/modify any watchers at this point.
557 786
558 See the EV::check watcher, below, for explanations and an example. 787 See the EV::check watcher, below, for explanations and an example.
559 788
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561 watcher. 790 watcher.
562 791
563 CHECK WATCHERS - customise your event loop even more! 792 CHECK WATCHERS - customise your event loop even more!
564 $w = EV::check $callback 793 $w = EV::check $callback
565 $w = EV::check_ns $callback 794 $w = EV::check_ns $callback
795 $w = $loop->check ($callback)
796 $w = $loop->check_ns ($callback)
566 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
567 has gathered events), but before any other callbacks have been 798 has gathered events), but before any other callbacks have been
568 invoked. 799 invoked.
569 800
570 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
571 mainloop: You register a prepare callback and in there, you create 802 mainloop: You register a prepare callback and in there, you create
572 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
573 real-world example of integrating Net::SNMP (with some details left 804 real-world example of integrating Net::SNMP (with some details left
574 out): 805 out):
575 806
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606 # make the dispatcher handle any new stuff 837 # make the dispatcher handle any new stuff
607 ... not shown 838 ... not shown
608 }; 839 };
609 840
610 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
611 watchers are destroyed before this cna happen (remember EV::check 842 watchers are destroyed before this can happen (remember EV::check
612 gets called first). 843 gets called first).
613 844
614 The "check_ns" variant doesn't start (activate) the newly created 845 The "check_ns" variant doesn't start (activate) the newly created
615 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.
616 856
617 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
618 Fork watchers are called when a "fork ()" was detected. The invocation 858 Fork watchers are called when a "fork ()" was detected. The invocation
619 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
620 are being called, and only in the child after the fork. 860 are being called, and only in the child after the fork.
621 861
622 $w = EV::fork $callback 862 $w = EV::fork $callback
623 $w = EV::fork_ns $callback 863 $w = EV::fork_ns $callback
864 $w = $loop->fork ($callback)
865 $w = $loop->fork_ns ($callback)
624 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
625 process after a fork. 867 process after a fork.
626 868
627 The "fork_ns" variant doesn't start (activate) the newly created 869 The "fork_ns" variant doesn't start (activate) the newly created
628 watcher. 870 watcher.
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
629 924
630PERL SIGNALS 925PERL SIGNALS
631 While Perl signal handling (%SIG) is not affected by EV, the behaviour 926 While Perl signal handling (%SIG) is not affected by EV, the behaviour
632 with EV is as the same as any other C library: Perl-signals will only be 927 with EV is as the same as any other C library: Perl-signals will only be
633 handled when Perl runs, which means your signal handler might be invoked 928 handled when Perl runs, which means your signal handler might be invoked
… …
640 to be called on every event loop iteration by installing a "EV::check" 935 to be called on every event loop iteration by installing a "EV::check"
641 watcher: 936 watcher:
642 937
643 my $async_check = EV::check sub { }; 938 my $async_check = EV::check sub { };
644 939
645 This ensures that perl shortly gets into control for a short time, and 940 This ensures that perl gets into control for a short time to handle any
646 also ensures slower overall operation. 941 pending signals, and also ensures (slightly) slower overall operation.
647 942
648THREADS 943ITHREADS
649 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
650 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
651 work on thread support for it. 946 Coro are fully supported (and enhanced support is available via
947 Coro::EV).
652 948
653FORK 949FORK
654 Most of the "improved" event delivering mechanisms of modern operating 950 Most of the "improved" event delivering mechanisms of modern operating
655 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
656 not supported and usually destructive). Libev makes it possible to work 952 not supported and usually destructive). Libev makes it possible to work
… …
666 962
667 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
668 course. 964 course.
669 965
670SEE ALSO 966SEE ALSO
671 EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event 967 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
672 loop), Coro::EV (efficient coroutines with EV). 968 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
969 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
970 agnostic and portable event driven programming.
673 971
674AUTHOR 972AUTHOR
675 Marc Lehmann <schmorp@schmorp.de> 973 Marc Lehmann <schmorp@schmorp.de>
676 http://home.schmorp.de/ 974 http://home.schmorp.de/
677 975

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