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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 7
8 # TIMERS 8 # TIMERS
9 9
10 my $w = EV::timer 2, 0, sub { 10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s"; 11 warn "is called after 2s";
12 }; 12 };
13 13
14 my $w = EV::timer 2, 2, sub { 14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)"; 15 warn "is called roughly every 2s (repeat = 2)";
16 }; 16 };
17 17
18 undef $w; # destroy event watcher again 18 undef $w; # destroy event watcher again
19 19
20 my $w = EV::periodic 0, 60, 0, sub { 20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly"; 21 warn "is called every minute, on the minute, exactly";
22 }; 22 };
23 23
24 # IO 24 # IO
25 25
26 my $w = EV::io *STDIN, EV::READ, sub { 26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask 27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>; 28 warn "stdin is readable, you entered: ", <STDIN>;
29 }; 29 };
30 30
31 # SIGNALS 31 # SIGNALS
32 32
33 my $w = EV::signal 'QUIT', sub { 33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n"; 34 warn "sigquit received\n";
35 }; 35 };
36 36
37 # CHILD/PID STATUS CHANGES 37 # CHILD/PID STATUS CHANGES
38 38
39 my $w = EV::child 666, sub { 39 my $w = EV::child 666, 0, sub {
40 my ($w, $revents) = @_; 40 my ($w, $revents) = @_;
41 my $status = $w->rstatus; 41 my $status = $w->rstatus;
42 }; 42 };
43 43
44 # STAT CHANGES
45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_;
47 warn $w->path, " has changed somehow.\n";
48 };
49
44 # MAINLOOP 50 # MAINLOOP
45 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
46 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
47 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
48 54
49DESCRIPTION 55DESCRIPTION
50 This module provides an interface to libev 56 This module provides an interface to libev
51 (<http://software.schmorp.de/pkg/libev.html>). While the documentation 57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
52 below is comprehensive, one might also consult the documentation of 58 below is comprehensive, one might also consult the documentation of
53 libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle 59 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
54 details on watcher semantics or some discussion on the available 60 perldoc EV::libev) for more subtle details on watcher semantics or some
55 backends, or how to force a specific backend with "LIBEV_FLAGS". 61 discussion on the available backends, or how to force a specific backend
62 with "LIBEV_FLAGS", or just about in any case because it has much more
63 detailed information.
64
65 This module is very fast and scalable. It is actually so fast that you
66 can use it through the AnyEvent module, stay portable to other event
67 loops (if you don't rely on any watcher types not available through it)
68 and still be faster than with any other event loop currently supported
69 in Perl.
70
71 MODULE EXPORTS
72 This module does not export any symbols.
73
74EVENT LOOPS
75 EV supports multiple event loops: There is a single "default event loop"
76 that can handle everything including signals and child watchers, and any
77 number of "dynamic event loops" that can use different backends (with
78 various limitations), but no child and signal watchers.
79
80 You do not have to do anything to create the default event loop: When
81 the module is loaded a suitable backend is selected on the premise of
82 selecting a working backend (which for example rules out kqueue on most
83 BSDs). Modules should, unless they have "special needs" always use the
84 default loop as this is fastest (perl-wise), best supported by other
85 modules (e.g. AnyEvent or Coro) and most portable event loop.
86
87 For specific programs you can create additional event loops dynamically.
88
89 If you want to take advantage of kqueue (which often works properly for
90 sockets only) even though the default loop doesn't enable it, you can
91 *embed* a kqueue loop into the default loop: running the default loop
92 will then also service the kqueue loop to some extent. See the example
93 in the section about embed watchers for an example on how to achieve
94 that.
95
96 $loop = new EV::Loop [$flags]
97 Create a new event loop as per the specified flags. Please refer to
98 the "ev_loop_new ()" function description in the libev documentation
99 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
100 ONS>, or locally-installed as EV::libev manpage) for more info.
101
102 The loop will automatically be destroyed when it is no longer
103 referenced by any watcher and the loop object goes out of scope.
104
105 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
106 is recommended, as only the default event loop is protected by this
107 module. If you *are* embedding this loop in the default loop, this
108 is not necessary, as "EV::embed" automatically does the right thing
109 on fork.
110
111 $loop->loop_fork
112 Must be called after a fork in the child, before entering or
113 continuing the event loop. An alternative is to use
114 "EV::FLAG_FORKCHECK" which calls this function automatically, at
115 some performance loss (refer to the libev documentation).
116
117 $loop->loop_verify
118 Calls "ev_verify" to make internal consistency checks (for debugging
119 libev) and abort the program if any data structures were found to be
120 corrupted.
121
122 $loop = EV::default_loop [$flags]
123 Return the default loop (which is a singleton object). Since this
124 module already creates the default loop with default flags,
125 specifying flags here will not have any effect unless you destroy
126 the default loop first, which isn't supported. So in short: don't do
127 it, and if you break it, you get to keep the pieces.
56 128
57BASIC INTERFACE 129BASIC INTERFACE
58 $EV::DIED 130 $EV::DIED
59 Must contain a reference to a function that is called when a 131 Must contain a reference to a function that is called when a
60 callback throws an exception (with $@ containing thr error). The 132 callback throws an exception (with $@ containing the error). The
61 default prints an informative message and continues. 133 default prints an informative message and continues.
62 134
63 If this callback throws an exception it will be silently ignored. 135 If this callback throws an exception it will be silently ignored.
136
137 $flags = EV::supported_backends
138 $flags = EV::recommended_backends
139 $flags = EV::embeddable_backends
140 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
141 this instance of EV, the set of recommended backends (supposed to be
142 good) for this platform and the set of embeddable backends (see
143 EMBED WATCHERS).
144
145 EV::sleep $seconds
146 Block the process for the given number of (fractional) seconds.
64 147
65 $time = EV::time 148 $time = EV::time
66 Returns the current time in (fractional) seconds since the epoch. 149 Returns the current time in (fractional) seconds since the epoch.
67 150
68 $time = EV::now 151 $time = EV::now
152 $time = $loop->now
69 Returns the time the last event loop iteration has been started. 153 Returns the time the last event loop iteration has been started.
70 This is the time that (relative) timers are based on, and refering 154 This is the time that (relative) timers are based on, and referring
71 to it is usually faster then calling EV::time. 155 to it is usually faster then calling EV::time.
72 156
73 $method = EV::method 157 EV::now_update
158 $loop->now_update
159 Establishes the current time by querying the kernel, updating the
160 time returned by "EV::now" in the progress. This is a costly
161 operation and is usually done automatically within "EV::loop".
162
163 This function is rarely useful, but when some event callback runs
164 for a very long time without entering the event loop, updating
165 libev's idea of the current time is a good idea.
166
167 EV::suspend
168 $loop->suspend
169 EV::resume
170 $loop->resume
171 These two functions suspend and resume a loop, for use when the loop
172 is not used for a while and timeouts should not be processed.
173
174 A typical use case would be an interactive program such as a game:
175 When the user presses "^Z" to suspend the game and resumes it an
176 hour later it would be best to handle timeouts as if no time had
177 actually passed while the program was suspended. This can be
178 achieved by calling "suspend" in your "SIGTSTP" handler, sending
179 yourself a "SIGSTOP" and calling "resume" directly afterwards to
180 resume timer processing.
181
182 Effectively, all "timer" watchers will be delayed by the time spend
183 between "suspend" and "resume", and all "periodic" watchers will be
184 rescheduled (that is, they will lose any events that would have
185 occured while suspended).
186
187 After calling "suspend" you must not call *any* function on the
188 given loop other than "resume", and you must not call "resume"
189 without a previous call to "suspend".
190
191 Calling "suspend"/"resume" has the side effect of updating the event
192 loop time (see "now_update").
193
194 $backend = EV::backend
195 $backend = $loop->backend
74 Returns an integer describing the backend used by libev 196 Returns an integer describing the backend used by libev
75 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 197 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
76 198
77 EV::loop [$flags] 199 EV::loop [$flags]
200 $loop->loop ([$flags])
78 Begin checking for events and calling callbacks. It returns when a 201 Begin checking for events and calling callbacks. It returns when a
79 callback calls EV::unloop. 202 callback calls EV::unloop.
80 203
81 The $flags argument can be one of the following: 204 The $flags argument can be one of the following:
82 205
83 0 as above 206 0 as above
84 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 207 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
85 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 208 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
86 209
87 EV::unloop [$how] 210 EV::unloop [$how]
211 $loop->unloop ([$how])
88 When called with no arguments or an argument of EV::UNLOOP_ONE, 212 When called with no arguments or an argument of EV::UNLOOP_ONE,
89 makes the innermost call to EV::loop return. 213 makes the innermost call to EV::loop return.
90 214
91 When called with an argument of EV::UNLOOP_ALL, all calls to 215 When called with an argument of EV::UNLOOP_ALL, all calls to
92 EV::loop will return as fast as possible. 216 EV::loop will return as fast as possible.
93 217
218 $count = EV::loop_count
219 $count = $loop->loop_count
220 Return the number of times the event loop has polled for new events.
221 Sometimes useful as a generation counter.
222
94 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 223 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
224 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
95 This function rolls together an I/O and a timer watcher for a single 225 This function rolls together an I/O and a timer watcher for a single
96 one-shot event without the need for managing a watcher object. 226 one-shot event without the need for managing a watcher object.
97 227
98 If $fh_or_undef is a filehandle or file descriptor, then $events 228 If $fh_or_undef is a filehandle or file descriptor, then $events
99 must be a bitset containing either "EV::READ", "EV::WRITE" or 229 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
104 If timeout is "undef" or negative, then there will be no timeout. 234 If timeout is "undef" or negative, then there will be no timeout.
105 Otherwise a EV::timer with this value will be started. 235 Otherwise a EV::timer with this value will be started.
106 236
107 When an error occurs or either the timeout or I/O watcher triggers, 237 When an error occurs or either the timeout or I/O watcher triggers,
108 then the callback will be called with the received event set (in 238 then the callback will be called with the received event set (in
109 general you can expect it to be a combination of "EV:ERROR", 239 general you can expect it to be a combination of "EV::ERROR",
110 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 240 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
111 241
112 EV::once doesn't return anything: the watchers stay active till 242 EV::once doesn't return anything: the watchers stay active till
113 either of them triggers, then they will be stopped and freed, and 243 either of them triggers, then they will be stopped and freed, and
114 the callback invoked. 244 the callback invoked.
115 245
116 WATCHER 246 EV::feed_fd_event ($fd, $revents)
247 $loop->feed_fd_event ($fd, $revents)
248 Feed an event on a file descriptor into EV. EV will react to this
249 call as if the readyness notifications specified by $revents (a
250 combination of "EV::READ" and "EV::WRITE") happened on the file
251 descriptor $fd.
252
253 EV::feed_signal_event ($signal)
254 Feed a signal event into EV. EV will react to this call as if the
255 signal specified by $signal had occured.
256
257 EV::set_io_collect_interval $time
258 $loop->set_io_collect_interval ($time)
259 EV::set_timeout_collect_interval $time
260 $loop->set_timeout_collect_interval ($time)
261 These advanced functions set the minimum block interval when polling
262 for I/O events and the minimum wait interval for timer events. See
263 the libev documentation at
264 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
265 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
266 detailed discussion.
267
268WATCHER OBJECTS
117 A watcher is an object that gets created to record your interest in some 269 A watcher is an object that gets created to record your interest in some
118 event. For instance, if you want to wait for STDIN to become readable, 270 event. For instance, if you want to wait for STDIN to become readable,
119 you would create an EV::io watcher for that: 271 you would create an EV::io watcher for that:
120 272
121 my $watcher = EV::io *STDIN, EV::READ, sub { 273 my $watcher = EV::io *STDIN, EV::READ, sub {
122 my ($watcher, $revents) = @_; 274 my ($watcher, $revents) = @_;
123 warn "yeah, STDIN should not be readable without blocking!\n" 275 warn "yeah, STDIN should now be readable without blocking!\n"
124 }; 276 };
125 277
126 All watchers can be active (waiting for events) or inactive (paused). 278 All watchers can be active (waiting for events) or inactive (paused).
127 Only active watchers will have their callbacks invoked. All callbacks 279 Only active watchers will have their callbacks invoked. All callbacks
128 will be called with at least two arguments: the watcher and a bitmask of 280 will be called with at least two arguments: the watcher and a bitmask of
129 received events. 281 received events.
130 282
131 Each watcher type has its associated bit in revents, so you can use the 283 Each watcher type has its associated bit in revents, so you can use the
132 same callback for multiple watchers. The event mask is named after the 284 same callback for multiple watchers. The event mask is named after the
133 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 285 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
134 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 286 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
135 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 287 events (which can set both EV::READ and EV::WRITE bits), and EV::timer
136 (which uses EV::TIMEOUT). 288 (which uses EV::TIMEOUT).
137 289
138 In the rare case where one wants to create a watcher but not start it at 290 In the rare case where one wants to create a watcher but not start it at
139 the same time, each constructor has a variant with a trailing "_ns" in 291 the same time, each constructor has a variant with a trailing "_ns" in
… …
145 297
146 Also, all methods changing some aspect of a watcher (->set, ->priority, 298 Also, all methods changing some aspect of a watcher (->set, ->priority,
147 ->fh and so on) automatically stop and start it again if it is active, 299 ->fh and so on) automatically stop and start it again if it is active,
148 which means pending events get lost. 300 which means pending events get lost.
149 301
150 WATCHER TYPES 302 COMMON WATCHER METHODS
151 Now lets move to the existing watcher types and asociated methods. 303 This section lists methods common to all watchers.
152
153 The following methods are available for all watchers. Then followes a
154 description of each watcher constructor (EV::io, EV::timer,
155 EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and
156 EV::check), followed by any type-specific methods (if any).
157 304
158 $w->start 305 $w->start
159 Starts a watcher if it isn't active already. Does nothing to an 306 Starts a watcher if it isn't active already. Does nothing to an
160 already active watcher. By default, all watchers start out in the 307 already active watcher. By default, all watchers start out in the
161 active state (see the description of the "_ns" variants if you need 308 active state (see the description of the "_ns" variants if you need
162 stopped watchers). 309 stopped watchers).
163 310
164 $w->stop 311 $w->stop
165 Stop a watcher if it is active. Also clear any pending events 312 Stop a watcher if it is active. Also clear any pending events
166 (events that have been received but that didn't yet result in a 313 (events that have been received but that didn't yet result in a
167 callback invocation), regardless of wether the watcher was active or 314 callback invocation), regardless of whether the watcher was active
168 not. 315 or not.
169 316
170 $bool = $w->is_active 317 $bool = $w->is_active
171 Returns true if the watcher is active, false otherwise. 318 Returns true if the watcher is active, false otherwise.
172 319
173 $current_data = $w->data 320 $current_data = $w->data
… …
196 The default priority of any newly-created watcher is 0. 343 The default priority of any newly-created watcher is 0.
197 344
198 Note that the priority semantics have not yet been fleshed out and 345 Note that the priority semantics have not yet been fleshed out and
199 are subject to almost certain change. 346 are subject to almost certain change.
200 347
201 $w->trigger ($revents) 348 $w->invoke ($revents)
202 Call the callback *now* with the given event mask. 349 Call the callback *now* with the given event mask.
350
351 $w->feed_event ($revents)
352 Feed some events on this watcher into EV. EV will react to this call
353 as if the watcher had received the given $revents mask.
354
355 $revents = $w->clear_pending
356 If the watcher is pending, this function clears its pending status
357 and returns its $revents bitset (as if its callback was invoked). If
358 the watcher isn't pending it does nothing and returns 0.
203 359
204 $previous_state = $w->keepalive ($bool) 360 $previous_state = $w->keepalive ($bool)
205 Normally, "EV::loop" will return when there are no active watchers 361 Normally, "EV::loop" will return when there are no active watchers
206 (which is a "deadlock" because no progress can be made anymore). 362 (which is a "deadlock" because no progress can be made anymore).
207 This is convinient because it allows you to start your watchers (and 363 This is convinient because it allows you to start your watchers (and
208 your jobs), call "EV::loop" once and when it returns you know that 364 your jobs), call "EV::loop" once and when it returns you know that
209 all your jobs are finished (or they forgot to register some watchers 365 all your jobs are finished (or they forgot to register some watchers
210 for their task :). 366 for their task :).
211 367
212 Sometimes, however, this gets in your way, for example when you the 368 Sometimes, however, this gets in your way, for example when the
213 module that calls "EV::loop" (usually the main program) is not the 369 module that calls "EV::loop" (usually the main program) is not the
214 same module as a long-living watcher (for example a DNS client 370 same module as a long-living watcher (for example a DNS client
215 module written by somebody else even). Then you might want any 371 module written by somebody else even). Then you might want any
216 outstanding requests to be handled, but you would not want to keep 372 outstanding requests to be handled, but you would not want to keep
217 "EV::loop" from returning just because you happen to have this 373 "EV::loop" from returning just because you happen to have this
… …
219 375
220 In this case you can clear the keepalive status, which means that 376 In this case you can clear the keepalive status, which means that
221 even though your watcher is active, it won't keep "EV::loop" from 377 even though your watcher is active, it won't keep "EV::loop" from
222 returning. 378 returning.
223 379
224 The initial value for keepalive is true (enabled), and you cna 380 The initial value for keepalive is true (enabled), and you can
225 change it any time. 381 change it any time.
226 382
227 Example: Register an IO watcher for some UDP socket but do not keep 383 Example: Register an I/O watcher for some UDP socket but do not keep
228 the event loop from running just because of that watcher. 384 the event loop from running just because of that watcher.
229 385
230 my $udp_socket = ... 386 my $udp_socket = ...
231 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 387 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
232 $udp_watcher->keepalive (0); 388 $udp_watcher->keepalive (0);
233 389
390 $loop = $w->loop
391 Return the loop that this watcher is attached to.
392
393WATCHER TYPES
394 Each of the following subsections describes a single watcher type.
395
396 I/O WATCHERS - is this file descriptor readable or writable?
234 $w = EV::io $fileno_or_fh, $eventmask, $callback 397 $w = EV::io $fileno_or_fh, $eventmask, $callback
235 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 398 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
399 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
400 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
236 As long as the returned watcher object is alive, call the $callback 401 As long as the returned watcher object is alive, call the $callback
237 when the events specified in $eventmask. 402 when at least one of events specified in $eventmask occurs.
238 403
239 The $eventmask can be one or more of these constants ORed together: 404 The $eventmask can be one or more of these constants ORed together:
240 405
241 EV::READ wait until read() wouldn't block anymore 406 EV::READ wait until read() wouldn't block anymore
242 EV::WRITE wait until write() wouldn't block anymore 407 EV::WRITE wait until write() wouldn't block anymore
… …
254 419
255 $current_eventmask = $w->events 420 $current_eventmask = $w->events
256 $old_eventmask = $w->events ($new_eventmask) 421 $old_eventmask = $w->events ($new_eventmask)
257 Returns the previously set event mask and optionally set a new one. 422 Returns the previously set event mask and optionally set a new one.
258 423
424 TIMER WATCHERS - relative and optionally repeating timeouts
259 $w = EV::timer $after, $repeat, $callback 425 $w = EV::timer $after, $repeat, $callback
260 $w = EV::timer_ns $after, $repeat, $callback 426 $w = EV::timer_ns $after, $repeat, $callback
427 $w = $loop->timer ($after, $repeat, $callback)
428 $w = $loop->timer_ns ($after, $repeat, $callback)
261 Calls the callback after $after seconds (which may be fractional). 429 Calls the callback after $after seconds (which may be fractional).
262 If $repeat is non-zero, the timer will be restarted (with the 430 If $repeat is non-zero, the timer will be restarted (with the
263 $repeat value as $after) after the callback returns. 431 $repeat value as $after) after the callback returns.
264 432
265 This means that the callback would be called roughly after $after 433 This means that the callback would be called roughly after $after
… …
277 The "timer_ns" variant doesn't start (activate) the newly created 445 The "timer_ns" variant doesn't start (activate) the newly created
278 watcher. 446 watcher.
279 447
280 $w->set ($after, $repeat) 448 $w->set ($after, $repeat)
281 Reconfigures the watcher, see the constructor above for details. Can 449 Reconfigures the watcher, see the constructor above for details. Can
282 be at any time. 450 be called at any time.
283 451
284 $w->again 452 $w->again
285 Similar to the "start" method, but has special semantics for 453 Similar to the "start" method, but has special semantics for
286 repeating timers: 454 repeating timers:
287 455
… …
298 This behaviour is useful when you have a timeout for some IO 466 This behaviour is useful when you have a timeout for some IO
299 operation. You create a timer object with the same value for $after 467 operation. You create a timer object with the same value for $after
300 and $repeat, and then, in the read/write watcher, run the "again" 468 and $repeat, and then, in the read/write watcher, run the "again"
301 method on the timeout. 469 method on the timeout.
302 470
471 PERIODIC WATCHERS - to cron or not to cron?
303 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 472 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
304 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 473 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
474 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
475 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
305 Similar to EV::timer, but is not based on relative timeouts but on 476 Similar to EV::timer, but is not based on relative timeouts but on
306 absolute times. Apart from creating "simple" timers that trigger 477 absolute times. Apart from creating "simple" timers that trigger
307 "at" the specified time, it can also be used for non-drifting 478 "at" the specified time, it can also be used for non-drifting
308 absolute timers and more complex, cron-like, setups that are not 479 absolute timers and more complex, cron-like, setups that are not
309 adversely affected by time jumps (i.e. when the system clock is 480 adversely affected by time jumps (i.e. when the system clock is
310 changed by explicit date -s or other means such as ntpd). It is also 481 changed by explicit date -s or other means such as ntpd). It is also
311 the most complex watcher type in EV. 482 the most complex watcher type in EV.
312 483
313 It has three distinct "modes": 484 It has three distinct "modes":
314 485
315 * absolute timer ($interval = $reschedule_cb = 0) 486 * absolute timer ($interval = $reschedule_cb = 0)
487
316 This time simply fires at the wallclock time $at and doesn't 488 This time simply fires at the wallclock time $at and doesn't
317 repeat. It will not adjust when a time jump occurs, that is, if 489 repeat. It will not adjust when a time jump occurs, that is, if
318 it is to be run at January 1st 2011 then it will run when the 490 it is to be run at January 1st 2011 then it will run when the
319 system time reaches or surpasses this time. 491 system time reaches or surpasses this time.
320 492
321 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 493 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
494
322 In this mode the watcher will always be scheduled to time out at 495 In this mode the watcher will always be scheduled to time out at
323 the next "$at + N * $interval" time (for some integer N) and 496 the next "$at + N * $interval" time (for some integer N) and
324 then repeat, regardless of any time jumps. 497 then repeat, regardless of any time jumps.
325 498
326 This can be used to create timers that do not drift with respect 499 This can be used to create timers that do not drift with respect
… …
335 Another way to think about it (for the mathematically inclined) 508 Another way to think about it (for the mathematically inclined)
336 is that EV::periodic will try to run the callback in this mode 509 is that EV::periodic will try to run the callback in this mode
337 at the next possible time where "$time = $at (mod $interval)", 510 at the next possible time where "$time = $at (mod $interval)",
338 regardless of any time jumps. 511 regardless of any time jumps.
339 512
340 * manual reschedule mode ($reschedule_cb = coderef) 513 * manual reschedule mode ($reschedule_cb = coderef)
514
341 In this mode $interval and $at are both being ignored. Instead, 515 In this mode $interval and $at are both being ignored. Instead,
342 each time the periodic watcher gets scheduled, the reschedule 516 each time the periodic watcher gets scheduled, the reschedule
343 callback ($reschedule_cb) will be called with the watcher as 517 callback ($reschedule_cb) will be called with the watcher as
344 first, and the current time as second argument. 518 first, and the current time as second argument.
345 519
346 *This callback MUST NOT stop or destroy this or any other 520 *This callback MUST NOT stop or destroy this or any other
521 periodic watcher, ever, and MUST NOT call any event loop
347 periodic watcher, ever*. If you need to stop it, return 1e30 and 522 functions or methods*. If you need to stop it, return 1e30 and
348 stop it afterwards. 523 stop it afterwards. You may create and start a "EV::prepare"
524 watcher for this task.
349 525
350 It must return the next time to trigger, based on the passed 526 It must return the next time to trigger, based on the passed
351 time value (that is, the lowest time value larger than to the 527 time value (that is, the lowest time value larger than or equal
352 second argument). It will usually be called just before the 528 to to the second argument). It will usually be called just
353 callback will be triggered, but might be called at other times, 529 before the callback will be triggered, but might be called at
354 too. 530 other times, too.
355 531
356 This can be used to create very complex timers, such as a timer 532 This can be used to create very complex timers, such as a timer
357 that triggers on each midnight, local time (actually 24 hours 533 that triggers on each midnight, local time (actually 24 hours
358 after the last midnight, to keep the example simple. If you know 534 after the last midnight, to keep the example simple. If you know
359 a way to do it correctly in about the same space (without 535 a way to do it correctly in about the same space (without
… …
372 The "periodic_ns" variant doesn't start (activate) the newly created 548 The "periodic_ns" variant doesn't start (activate) the newly created
373 watcher. 549 watcher.
374 550
375 $w->set ($at, $interval, $reschedule_cb) 551 $w->set ($at, $interval, $reschedule_cb)
376 Reconfigures the watcher, see the constructor above for details. Can 552 Reconfigures the watcher, see the constructor above for details. Can
377 be at any time. 553 be called at any time.
378 554
379 $w->again 555 $w->again
380 Simply stops and starts the watcher again. 556 Simply stops and starts the watcher again.
381 557
558 $time = $w->at
559 Return the time that the watcher is expected to trigger next.
560
561 SIGNAL WATCHERS - signal me when a signal gets signalled!
382 $w = EV::signal $signal, $callback 562 $w = EV::signal $signal, $callback
383 $w = EV::signal_ns $signal, $callback 563 $w = EV::signal_ns $signal, $callback
384 Call the callback when $signal is received (the signal can be 564 Call the callback when $signal is received (the signal can be
385 specified by number or by name, just as with kill or %SIG). 565 specified by number or by name, just as with "kill" or %SIG).
386 566
387 EV will grab the signal for the process (the kernel only allows one 567 EV will grab the signal for the process (the kernel only allows one
388 component to receive a signal at a time) when you start a signal 568 component to receive a signal at a time) when you start a signal
389 watcher, and removes it again when you stop it. Perl does the same 569 watcher, and removes it again when you stop it. Perl does the same
390 when you add/remove callbacks to %SIG, so watch out. 570 when you add/remove callbacks to %SIG, so watch out.
… …
394 The "signal_ns" variant doesn't start (activate) the newly created 574 The "signal_ns" variant doesn't start (activate) the newly created
395 watcher. 575 watcher.
396 576
397 $w->set ($signal) 577 $w->set ($signal)
398 Reconfigures the watcher, see the constructor above for details. Can 578 Reconfigures the watcher, see the constructor above for details. Can
399 be at any time. 579 be called at any time.
400 580
401 $current_signum = $w->signal 581 $current_signum = $w->signal
402 $old_signum = $w->signal ($new_signal) 582 $old_signum = $w->signal ($new_signal)
403 Returns the previously set signal (always as a number not name) and 583 Returns the previously set signal (always as a number not name) and
404 optionally set a new one. 584 optionally set a new one.
405 585
586 CHILD WATCHERS - watch out for process status changes
406 $w = EV::child $pid, $callback 587 $w = EV::child $pid, $trace, $callback
407 $w = EV::child_ns $pid, $callback 588 $w = EV::child_ns $pid, $trace, $callback
589 $w = $loop->child ($pid, $trace, $callback)
590 $w = $loop->child_ns ($pid, $trace, $callback)
408 Call the callback when a status change for pid $pid (or any pid if 591 Call the callback when a status change for pid $pid (or any pid if
409 $pid is 0) has been received. More precisely: when the process 592 $pid is 0) has been received (a status change happens when the
593 process terminates or is killed, or, when trace is true,
594 additionally when it is stopped or continued). More precisely: when
410 receives a SIGCHLD, EV will fetch the outstanding exit/wait status 595 the process receives a "SIGCHLD", EV will fetch the outstanding
411 for all changed/zombie children and call the callback. 596 exit/wait status for all changed/zombie children and call the
597 callback.
412 598
413 You can access both status and pid by using the "rstatus" and "rpid" 599 It is valid (and fully supported) to install a child watcher after a
600 child has exited but before the event loop has started its next
601 iteration (for example, first you "fork", then the new child process
602 might exit, and only then do you install a child watcher in the
603 parent for the new pid).
604
605 You can access both exit (or tracing) status and pid by using the
414 methods on the watcher object. 606 "rstatus" and "rpid" methods on the watcher object.
415 607
416 You can have as many pid watchers per pid as you want. 608 You can have as many pid watchers per pid as you want, they will all
609 be called.
417 610
418 The "child_ns" variant doesn't start (activate) the newly created 611 The "child_ns" variant doesn't start (activate) the newly created
419 watcher. 612 watcher.
420 613
421 $w->set ($pid) 614 $w->set ($pid, $trace)
422 Reconfigures the watcher, see the constructor above for details. Can 615 Reconfigures the watcher, see the constructor above for details. Can
423 be at any time. 616 be called at any time.
424 617
425 $current_pid = $w->pid 618 $current_pid = $w->pid
426 $old_pid = $w->pid ($new_pid)
427 Returns the previously set process id and optionally set a new one. 619 Returns the previously set process id and optionally set a new one.
428 620
429 $exit_status = $w->rstatus 621 $exit_status = $w->rstatus
430 Return the exit/wait status (as returned by waitpid, see the waitpid 622 Return the exit/wait status (as returned by waitpid, see the waitpid
431 entry in perlfunc). 623 entry in perlfunc).
432 624
433 $pid = $w->rpid 625 $pid = $w->rpid
434 Return the pid of the awaited child (useful when you have installed 626 Return the pid of the awaited child (useful when you have installed
435 a watcher for all pids). 627 a watcher for all pids).
436 628
629 STAT WATCHERS - did the file attributes just change?
630 $w = EV::stat $path, $interval, $callback
631 $w = EV::stat_ns $path, $interval, $callback
632 $w = $loop->stat ($path, $interval, $callback)
633 $w = $loop->stat_ns ($path, $interval, $callback)
634 Call the callback when a file status change has been detected on
635 $path. The $path does not need to exist, changing from "path exists"
636 to "path does not exist" is a status change like any other.
637
638 The $interval is a recommended polling interval for systems where
639 OS-supported change notifications don't exist or are not supported.
640 If you use 0 then an unspecified default is used (which is highly
641 recommended!), which is to be expected to be around five seconds
642 usually.
643
644 This watcher type is not meant for massive numbers of stat watchers,
645 as even with OS-supported change notifications, this can be
646 resource-intensive.
647
648 The "stat_ns" variant doesn't start (activate) the newly created
649 watcher.
650
651 ... = $w->stat
652 This call is very similar to the perl "stat" built-in: It stats
653 (using "lstat") the path specified in the watcher and sets perls
654 stat cache (as well as EV's idea of the current stat values) to the
655 values found.
656
657 In scalar context, a boolean is return indicating success or failure
658 of the stat. In list context, the same 13-value list as with stat is
659 returned (except that the blksize and blocks fields are not
660 reliable).
661
662 In the case of an error, errno is set to "ENOENT" (regardless of the
663 actual error value) and the "nlink" value is forced to zero (if the
664 stat was successful then nlink is guaranteed to be non-zero).
665
666 See also the next two entries for more info.
667
668 ... = $w->attr
669 Just like "$w->stat", but without the initial stat'ing: this returns
670 the values most recently detected by EV. See the next entry for more
671 info.
672
673 ... = $w->prev
674 Just like "$w->stat", but without the initial stat'ing: this returns
675 the previous set of values, before the change.
676
677 That is, when the watcher callback is invoked, "$w->prev" will be
678 set to the values found *before* a change was detected, while
679 "$w->attr" returns the values found leading to the change detection.
680 The difference (if any) between "prev" and "attr" is what triggered
681 the callback.
682
683 If you did something to the filesystem object and do not want to
684 trigger yet another change, you can call "stat" to update EV's idea
685 of what the current attributes are.
686
687 $w->set ($path, $interval)
688 Reconfigures the watcher, see the constructor above for details. Can
689 be called at any time.
690
691 $current_path = $w->path
692 $old_path = $w->path ($new_path)
693 Returns the previously set path and optionally set a new one.
694
695 $current_interval = $w->interval
696 $old_interval = $w->interval ($new_interval)
697 Returns the previously set interval and optionally set a new one.
698 Can be used to query the actual interval used.
699
700 IDLE WATCHERS - when you've got nothing better to do...
437 $w = EV::idle $callback 701 $w = EV::idle $callback
438 $w = EV::idle_ns $callback 702 $w = EV::idle_ns $callback
703 $w = $loop->idle ($callback)
704 $w = $loop->idle_ns ($callback)
439 Call the callback when there are no pending io, timer/periodic, 705 Call the callback when there are no other pending watchers of the
440 signal or child events, i.e. when the process is idle. 706 same or higher priority (excluding check, prepare and other idle
707 watchers of the same or lower priority, of course). They are called
708 idle watchers because when the watcher is the highest priority
709 pending event in the process, the process is considered to be idle
710 at that priority.
711
712 If you want a watcher that is only ever called when *no* other
713 events are outstanding you have to set the priority to "EV::MINPRI".
441 714
442 The process will not block as long as any idle watchers are active, 715 The process will not block as long as any idle watchers are active,
443 and they will be called repeatedly until stopped. 716 and they will be called repeatedly until stopped.
444 717
718 For example, if you have idle watchers at priority 0 and 1, and an
719 I/O watcher at priority 0, then the idle watcher at priority 1 and
720 the I/O watcher will always run when ready. Only when the idle
721 watcher at priority 1 is stopped and the I/O watcher at priority 0
722 is not pending with the 0-priority idle watcher be invoked.
723
445 The "idle_ns" variant doesn't start (activate) the newly created 724 The "idle_ns" variant doesn't start (activate) the newly created
446 watcher. 725 watcher.
447 726
727 PREPARE WATCHERS - customise your event loop!
448 $w = EV::prepare $callback 728 $w = EV::prepare $callback
449 $w = EV::prepare_ns $callback 729 $w = EV::prepare_ns $callback
730 $w = $loop->prepare ($callback)
731 $w = $loop->prepare_ns ($callback)
450 Call the callback just before the process would block. You can still 732 Call the callback just before the process would block. You can still
451 create/modify any watchers at this point. 733 create/modify any watchers at this point.
452 734
453 See the EV::check watcher, below, for explanations and an example. 735 See the EV::check watcher, below, for explanations and an example.
454 736
455 The "prepare_ns" variant doesn't start (activate) the newly created 737 The "prepare_ns" variant doesn't start (activate) the newly created
456 watcher. 738 watcher.
457 739
740 CHECK WATCHERS - customise your event loop even more!
458 $w = EV::check $callback 741 $w = EV::check $callback
459 $w = EV::check_ns $callback 742 $w = EV::check_ns $callback
743 $w = $loop->check ($callback)
744 $w = $loop->check_ns ($callback)
460 Call the callback just after the process wakes up again (after it 745 Call the callback just after the process wakes up again (after it
461 has gathered events), but before any other callbacks have been 746 has gathered events), but before any other callbacks have been
462 invoked. 747 invoked.
463 748
464 This is used to integrate other event-based software into the EV 749 This is used to integrate other event-based software into the EV
… …
475 or return; 760 or return;
476 761
477 # make the dispatcher handle any outstanding stuff 762 # make the dispatcher handle any outstanding stuff
478 ... not shown 763 ... not shown
479 764
480 # create an IO watcher for each and every socket 765 # create an I/O watcher for each and every socket
481 @snmp_watcher = ( 766 @snmp_watcher = (
482 (map { EV::io $_, EV::READ, sub { } } 767 (map { EV::io $_, EV::READ, sub { } }
483 keys %{ $dispatcher->{_descriptors} }), 768 keys %{ $dispatcher->{_descriptors} }),
484 769
485 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 770 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
… …
500 # make the dispatcher handle any new stuff 785 # make the dispatcher handle any new stuff
501 ... not shown 786 ... not shown
502 }; 787 };
503 788
504 The callbacks of the created watchers will not be called as the 789 The callbacks of the created watchers will not be called as the
505 watchers are destroyed before this cna happen (remember EV::check 790 watchers are destroyed before this can happen (remember EV::check
506 gets called first). 791 gets called first).
507 792
508 The "check_ns" variant doesn't start (activate) the newly created 793 The "check_ns" variant doesn't start (activate) the newly created
509 watcher. 794 watcher.
795
796 FORK WATCHERS - the audacity to resume the event loop after a fork
797 Fork watchers are called when a "fork ()" was detected. The invocation
798 is done before the event loop blocks next and before "check" watchers
799 are being called, and only in the child after the fork.
800
801 $w = EV::fork $callback
802 $w = EV::fork_ns $callback
803 $w = $loop->fork ($callback)
804 $w = $loop->fork_ns ($callback)
805 Call the callback before the event loop is resumed in the child
806 process after a fork.
807
808 The "fork_ns" variant doesn't start (activate) the newly created
809 watcher.
810
811 EMBED WATCHERS - when one backend isn't enough...
812 This is a rather advanced watcher type that lets you embed one event
813 loop into another (currently only IO events are supported in the
814 embedded loop, other types of watchers might be handled in a delayed or
815 incorrect fashion and must not be used).
816
817 See the libev documentation at
818 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
819 _when_one_backend_> (locally installed as EV::libev) for more details.
820
821 In short, this watcher is most useful on BSD systems without working
822 kqueue to still be able to handle a large number of sockets:
823
824 my $socket_loop;
825
826 # check wether we use SELECT or POLL _and_ KQUEUE is supported
827 if (
828 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
829 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
830 ) {
831 # use kqueue for sockets
832 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
833 }
834
835 # use the default loop otherwise
836 $socket_loop ||= EV::default_loop;
837
838 $w = EV::embed $otherloop[, $callback]
839 $w = EV::embed_ns $otherloop[, $callback]
840 $w = $loop->embed ($otherloop[, $callback])
841 $w = $loop->embed_ns ($otherloop[, $callback])
842 Call the callback when the embedded event loop ($otherloop) has any
843 I/O activity. The $callback is optional: if it is missing, then the
844 embedded event loop will be managed automatically (which is
845 recommended), otherwise you have to invoke "sweep" yourself.
846
847 The "embed_ns" variant doesn't start (activate) the newly created
848 watcher.
849
850 ASYNC WATCHERS - how to wake up another event loop
851 Async watchers are provided by EV, but have little use in perl directly,
852 as perl neither supports threads nor direct access to signal handlers or
853 other contexts where they could be of value.
854
855 It is, however, possible to use them from the XS level.
856
857 Please see the libev documentation for further details.
858
859 $w = EV::async $callback
860 $w = EV::async_ns $callback
861 $w->send
862 $bool = $w->async_pending
863
864PERL SIGNALS
865 While Perl signal handling (%SIG) is not affected by EV, the behaviour
866 with EV is as the same as any other C library: Perl-signals will only be
867 handled when Perl runs, which means your signal handler might be invoked
868 only the next time an event callback is invoked.
869
870 The solution is to use EV signal watchers (see "EV::signal"), which will
871 ensure proper operations with regards to other event watchers.
872
873 If you cannot do this for whatever reason, you can also force a watcher
874 to be called on every event loop iteration by installing a "EV::check"
875 watcher:
876
877 my $async_check = EV::check sub { };
878
879 This ensures that perl gets into control for a short time to handle any
880 pending signals, and also ensures (slightly) slower overall operation.
510 881
511THREADS 882THREADS
512 Threads are not supported by this module in any way. Perl pseudo-threads 883 Threads are not supported by this module in any way. Perl pseudo-threads
513 is evil stuff and must die. As soon as Perl gains real threads I will 884 is evil stuff and must die. As soon as Perl gains real threads I will
514 work on thread support for it. 885 work on thread support for it.
… …
529 900
530 On win32, there is no notion of fork so all this doesn't apply, of 901 On win32, there is no notion of fork so all this doesn't apply, of
531 course. 902 course.
532 903
533SEE ALSO 904SEE ALSO
534 L<EV::DNS>. 905 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
906 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
907 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
908 agnostic and portable event driven programming.
535 909
536AUTHOR 910AUTHOR
537 Marc Lehmann <schmorp@schmorp.de> 911 Marc Lehmann <schmorp@schmorp.de>
538 http://home.schmorp.de/ 912 http://home.schmorp.de/
539 913

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