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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 MODULE EXPORTS
81 This module does not export any symbols.
82
83EVENT LOOPS
84 EV supports multiple event loops: There is a single "default event loop"
85 that can handle everything including signals and child watchers, and any
86 number of "dynamic event loops" that can use different backends (with
87 various limitations), but no child and signal watchers.
88
89 You do not have to do anything to create the default event loop: When
90 the module is loaded a suitable backend is selected on the premise of
91 selecting a working backend (which for example rules out kqueue on most
92 BSDs). Modules should, unless they have "special needs" always use the
93 default loop as this is fastest (perl-wise), best supported by other
94 modules (e.g. AnyEvent or Coro) and most portable event loop.
95
96 For specific programs you can create additional event loops dynamically.
97
98 If you want to take advantage of kqueue (which often works properly for
99 sockets only) even though the default loop doesn't enable it, you can
100 *embed* a kqueue loop into the default loop: running the default loop
101 will then also service the kqueue loop to some extent. See the example
102 in the section about embed watchers for an example on how to achieve
103 that.
104
105 $loop = new EV::Loop [$flags]
106 Create a new event loop as per the specified flags. Please refer to
107 the "ev_loop_new ()" function description in the libev documentation
108 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
109 ONS>, or locally-installed as EV::libev manpage) for more info.
110
111 The loop will automatically be destroyed when it is no longer
112 referenced by any watcher and the loop object goes out of scope.
113
114 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
115 is recommended, as only the default event loop is protected by this
116 module. If you *are* embedding this loop in the default loop, this
117 is not necessary, as "EV::embed" automatically does the right thing
118 on fork.
119
120 $loop->loop_fork
121 Must be called after a fork in the child, before entering or
122 continuing the event loop. An alternative is to use
123 "EV::FLAG_FORKCHECK" which calls this function automatically, at
124 some performance loss (refer to the libev documentation).
125
126 $loop->loop_verify
127 Calls "ev_verify" to make internal consistency checks (for debugging
128 libev) and abort the program if any data structures were found to be
129 corrupted.
130
131 $loop = EV::default_loop [$flags]
132 Return the default loop (which is a singleton object). Since this
133 module already creates the default loop with default flags,
134 specifying flags here will not have any effect unless you destroy
135 the default loop first, which isn't supported. So in short: don't do
136 it, and if you break it, you get to keep the pieces.
63 137
64BASIC INTERFACE 138BASIC INTERFACE
65 $EV::DIED 139 $EV::DIED
66 Must contain a reference to a function that is called when a 140 Must contain a reference to a function that is called when a
67 callback throws an exception (with $@ containing thr error). The 141 callback throws an exception (with $@ containing the error). The
68 default prints an informative message and continues. 142 default prints an informative message and continues.
69 143
70 If this callback throws an exception it will be silently ignored. 144 If this callback throws an exception it will be silently ignored.
145
146 $flags = EV::supported_backends
147 $flags = EV::recommended_backends
148 $flags = EV::embeddable_backends
149 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
150 this instance of EV, the set of recommended backends (supposed to be
151 good) for this platform and the set of embeddable backends (see
152 EMBED WATCHERS).
153
154 EV::sleep $seconds
155 Block the process for the given number of (fractional) seconds.
71 156
72 $time = EV::time 157 $time = EV::time
73 Returns the current time in (fractional) seconds since the epoch. 158 Returns the current time in (fractional) seconds since the epoch.
74 159
75 $time = EV::now 160 $time = EV::now
161 $time = $loop->now
76 Returns the time the last event loop iteration has been started. 162 Returns the time the last event loop iteration has been started.
77 This is the time that (relative) timers are based on, and refering 163 This is the time that (relative) timers are based on, and referring
78 to it is usually faster then calling EV::time. 164 to it is usually faster then calling EV::time.
79 165
80 $method = EV::method 166 EV::now_update
167 $loop->now_update
168 Establishes the current time by querying the kernel, updating the
169 time returned by "EV::now" in the progress. This is a costly
170 operation and is usually done automatically within "EV::loop".
171
172 This function is rarely useful, but when some event callback runs
173 for a very long time without entering the event loop, updating
174 libev's idea of the current time is a good idea.
175
176 EV::suspend
177 $loop->suspend
178 EV::resume
179 $loop->resume
180 These two functions suspend and resume a loop, for use when the loop
181 is not used for a while and timeouts should not be processed.
182
183 A typical use case would be an interactive program such as a game:
184 When the user presses "^Z" to suspend the game and resumes it an
185 hour later it would be best to handle timeouts as if no time had
186 actually passed while the program was suspended. This can be
187 achieved by calling "suspend" in your "SIGTSTP" handler, sending
188 yourself a "SIGSTOP" and calling "resume" directly afterwards to
189 resume timer processing.
190
191 Effectively, all "timer" watchers will be delayed by the time spend
192 between "suspend" and "resume", and all "periodic" watchers will be
193 rescheduled (that is, they will lose any events that would have
194 occured while suspended).
195
196 After calling "suspend" you must not call *any* function on the
197 given loop other than "resume", and you must not call "resume"
198 without a previous call to "suspend".
199
200 Calling "suspend"/"resume" has the side effect of updating the event
201 loop time (see "now_update").
202
203 $backend = EV::backend
204 $backend = $loop->backend
81 Returns an integer describing the backend used by libev 205 Returns an integer describing the backend used by libev
82 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 206 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
83 207
84 EV::loop [$flags] 208 EV::loop [$flags]
209 $loop->loop ([$flags])
85 Begin checking for events and calling callbacks. It returns when a 210 Begin checking for events and calling callbacks. It returns when a
86 callback calls EV::unloop. 211 callback calls EV::unloop.
87 212
88 The $flags argument can be one of the following: 213 The $flags argument can be one of the following:
89 214
90 0 as above 215 0 as above
91 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 216 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
92 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 217 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
93 218
94 EV::unloop [$how] 219 EV::unloop [$how]
220 $loop->unloop ([$how])
95 When called with no arguments or an argument of EV::UNLOOP_ONE, 221 When called with no arguments or an argument of EV::UNLOOP_ONE,
96 makes the innermost call to EV::loop return. 222 makes the innermost call to EV::loop return.
97 223
98 When called with an argument of EV::UNLOOP_ALL, all calls to 224 When called with an argument of EV::UNLOOP_ALL, all calls to
99 EV::loop will return as fast as possible. 225 EV::loop will return as fast as possible.
100 226
101 $count = EV::loop_count 227 $count = EV::loop_count
228 $count = $loop->loop_count
102 Return the number of times the event loop has polled for new events. 229 Return the number of times the event loop has polled for new events.
103 Sometiems useful as a generation counter. 230 Sometimes useful as a generation counter.
104 231
105 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 232 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
233 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
106 This function rolls together an I/O and a timer watcher for a single 234 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. 235 one-shot event without the need for managing a watcher object.
108 236
109 If $fh_or_undef is a filehandle or file descriptor, then $events 237 If $fh_or_undef is a filehandle or file descriptor, then $events
110 must be a bitset containing either "EV::READ", "EV::WRITE" or 238 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
115 If timeout is "undef" or negative, then there will be no timeout. 243 If timeout is "undef" or negative, then there will be no timeout.
116 Otherwise a EV::timer with this value will be started. 244 Otherwise a EV::timer with this value will be started.
117 245
118 When an error occurs or either the timeout or I/O watcher triggers, 246 When an error occurs or either the timeout or I/O watcher triggers,
119 then the callback will be called with the received event set (in 247 then the callback will be called with the received event set (in
120 general you can expect it to be a combination of "EV:ERROR", 248 general you can expect it to be a combination of "EV::ERROR",
121 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 249 "EV::READ", "EV::WRITE" and "EV::TIMER").
122 250
123 EV::once doesn't return anything: the watchers stay active till 251 EV::once doesn't return anything: the watchers stay active till
124 either of them triggers, then they will be stopped and freed, and 252 either of them triggers, then they will be stopped and freed, and
125 the callback invoked. 253 the callback invoked.
126 254
127 EV::feed_fd_event ($fd, $revents) 255 EV::feed_fd_event ($fd, $revents)
256 $loop->feed_fd_event ($fd, $revents)
128 Feed an event on a file descriptor into EV. EV will react to this 257 Feed an event on a file descriptor into EV. EV will react to this
129 call as if the readyness notifications specified by $revents (a 258 call as if the readyness notifications specified by $revents (a
130 combination of "EV::READ" and "EV::WRITE") happened on the file 259 combination of "EV::READ" and "EV::WRITE") happened on the file
131 descriptor $fd. 260 descriptor $fd.
132 261
133 EV::feed_signal_event ($signal) 262 EV::feed_signal_event ($signal)
134 Feed a signal event into EV. EV will react to this call as if the 263 Feed a signal event into EV. EV will react to this call as if the
135 signal specified by $signal had occured. 264 signal specified by $signal had occured.
136 265
266 EV::set_io_collect_interval $time
267 $loop->set_io_collect_interval ($time)
268 EV::set_timeout_collect_interval $time
269 $loop->set_timeout_collect_interval ($time)
270 These advanced functions set the minimum block interval when polling
271 for I/O events and the minimum wait interval for timer events. See
272 the libev documentation at
273 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
274 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
275 detailed discussion.
276
277 $count = EV::pending_count
278 $count = $loop->pending_count
279 Returns the number of currently pending watchers.
280
281 EV::invoke_pending
282 $loop->invoke_pending
283 Invoke all currently pending watchers.
284
137 WATCHER OBJECTS 285WATCHER OBJECTS
138 A watcher is an object that gets created to record your interest in some 286 A watcher is an object that gets created to record your interest in some
139 event. For instance, if you want to wait for STDIN to become readable, 287 event. For instance, if you want to wait for STDIN to become readable,
140 you would create an EV::io watcher for that: 288 you would create an EV::io watcher for that:
141 289
142 my $watcher = EV::io *STDIN, EV::READ, sub { 290 my $watcher = EV::io *STDIN, EV::READ, sub {
143 my ($watcher, $revents) = @_; 291 my ($watcher, $revents) = @_;
144 warn "yeah, STDIN should not be readable without blocking!\n" 292 warn "yeah, STDIN should now be readable without blocking!\n"
145 }; 293 };
146 294
147 All watchers can be active (waiting for events) or inactive (paused). 295 All watchers can be active (waiting for events) or inactive (paused).
148 Only active watchers will have their callbacks invoked. All callbacks 296 Only active watchers will have their callbacks invoked. All callbacks
149 will be called with at least two arguments: the watcher and a bitmask of 297 will be called with at least two arguments: the watcher and a bitmask of
150 received events. 298 received events.
151 299
152 Each watcher type has its associated bit in revents, so you can use the 300 Each watcher type has its associated bit in revents, so you can use the
153 same callback for multiple watchers. The event mask is named after the 301 same callback for multiple watchers. The event mask is named after the
154 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 302 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
155 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O 303 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
156 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 304 events (which can set both EV::READ and EV::WRITE bits).
157 (which uses EV::TIMEOUT).
158 305
159 In the rare case where one wants to create a watcher but not start it at 306 In the rare case where one wants to create a watcher but not start it at
160 the same time, each constructor has a variant with a trailing "_ns" in 307 the same time, each constructor has a variant with a trailing "_ns" in
161 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 308 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
162 309
… …
220 $w->feed_event ($revents) 367 $w->feed_event ($revents)
221 Feed some events on this watcher into EV. EV will react to this call 368 Feed some events on this watcher into EV. EV will react to this call
222 as if the watcher had received the given $revents mask. 369 as if the watcher had received the given $revents mask.
223 370
224 $revents = $w->clear_pending 371 $revents = $w->clear_pending
225 If the watcher is pending, this function returns clears its pending 372 If the watcher is pending, this function clears its pending status
226 status and returns its $revents bitset (as if its callback was 373 and returns its $revents bitset (as if its callback was invoked). If
227 invoked). If the watcher isn't pending it does nothing and returns 374 the watcher isn't pending it does nothing and returns 0.
228 0.
229 375
230 $previous_state = $w->keepalive ($bool) 376 $previous_state = $w->keepalive ($bool)
231 Normally, "EV::loop" will return when there are no active watchers 377 Normally, "EV::loop" will return when there are no active watchers
232 (which is a "deadlock" because no progress can be made anymore). 378 (which is a "deadlock" because no progress can be made anymore).
233 This is convinient because it allows you to start your watchers (and 379 This is convenient because it allows you to start your watchers (and
234 your jobs), call "EV::loop" once and when it returns you know that 380 your jobs), call "EV::loop" once and when it returns you know that
235 all your jobs are finished (or they forgot to register some watchers 381 all your jobs are finished (or they forgot to register some watchers
236 for their task :). 382 for their task :).
237 383
238 Sometimes, however, this gets in your way, for example when you the 384 Sometimes, however, this gets in your way, for example when the
239 module that calls "EV::loop" (usually the main program) is not the 385 module that calls "EV::loop" (usually the main program) is not the
240 same module as a long-living watcher (for example a DNS client 386 same module as a long-living watcher (for example a DNS client
241 module written by somebody else even). Then you might want any 387 module written by somebody else even). Then you might want any
242 outstanding requests to be handled, but you would not want to keep 388 outstanding requests to be handled, but you would not want to keep
243 "EV::loop" from returning just because you happen to have this 389 "EV::loop" from returning just because you happen to have this
… …
245 391
246 In this case you can clear the keepalive status, which means that 392 In this case you can clear the keepalive status, which means that
247 even though your watcher is active, it won't keep "EV::loop" from 393 even though your watcher is active, it won't keep "EV::loop" from
248 returning. 394 returning.
249 395
250 The initial value for keepalive is true (enabled), and you cna 396 The initial value for keepalive is true (enabled), and you can
251 change it any time. 397 change it any time.
252 398
253 Example: Register an I/O watcher for some UDP socket but do not keep 399 Example: Register an I/O watcher for some UDP socket but do not keep
254 the event loop from running just because of that watcher. 400 the event loop from running just because of that watcher.
255 401
256 my $udp_socket = ... 402 my $udp_socket = ...
257 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 403 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
258 $udp_watcher->keepalive (0); 404 $udp_watcher->keepalive (0);
259 405
406 $loop = $w->loop
407 Return the loop that this watcher is attached to.
408
260 WATCHER TYPES 409WATCHER TYPES
261 Each of the following subsections describes a single watcher type. 410 Each of the following subsections describes a single watcher type.
262 411
263 I/O WATCHERS - is this file descriptor readable or writable? 412 I/O WATCHERS - is this file descriptor readable or writable?
264 $w = EV::io $fileno_or_fh, $eventmask, $callback 413 $w = EV::io $fileno_or_fh, $eventmask, $callback
265 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 414 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
415 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
416 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
266 As long as the returned watcher object is alive, call the $callback 417 As long as the returned watcher object is alive, call the $callback
267 when at least one of events specified in $eventmask occurs. 418 when at least one of events specified in $eventmask occurs.
268 419
269 The $eventmask can be one or more of these constants ORed together: 420 The $eventmask can be one or more of these constants ORed together:
270 421
… …
287 Returns the previously set event mask and optionally set a new one. 438 Returns the previously set event mask and optionally set a new one.
288 439
289 TIMER WATCHERS - relative and optionally repeating timeouts 440 TIMER WATCHERS - relative and optionally repeating timeouts
290 $w = EV::timer $after, $repeat, $callback 441 $w = EV::timer $after, $repeat, $callback
291 $w = EV::timer_ns $after, $repeat, $callback 442 $w = EV::timer_ns $after, $repeat, $callback
443 $w = $loop->timer ($after, $repeat, $callback)
444 $w = $loop->timer_ns ($after, $repeat, $callback)
292 Calls the callback after $after seconds (which may be fractional). 445 Calls the callback after $after seconds (which may be fractional).
293 If $repeat is non-zero, the timer will be restarted (with the 446 If $repeat is non-zero, the timer will be restarted (with the
294 $repeat value as $after) after the callback returns. 447 $repeat value as $after) after the callback returns.
295 448
296 This means that the callback would be called roughly after $after 449 This means that the callback would be called roughly after $after
… …
332 method on the timeout. 485 method on the timeout.
333 486
334 PERIODIC WATCHERS - to cron or not to cron? 487 PERIODIC WATCHERS - to cron or not to cron?
335 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 488 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
336 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 489 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
490 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
491 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
337 Similar to EV::timer, but is not based on relative timeouts but on 492 Similar to EV::timer, but is not based on relative timeouts but on
338 absolute times. Apart from creating "simple" timers that trigger 493 absolute times. Apart from creating "simple" timers that trigger
339 "at" the specified time, it can also be used for non-drifting 494 "at" the specified time, it can also be used for non-drifting
340 absolute timers and more complex, cron-like, setups that are not 495 absolute timers and more complex, cron-like, setups that are not
341 adversely affected by time jumps (i.e. when the system clock is 496 adversely affected by time jumps (i.e. when the system clock is
342 changed by explicit date -s or other means such as ntpd). It is also 497 changed by explicit date -s or other means such as ntpd). It is also
343 the most complex watcher type in EV. 498 the most complex watcher type in EV.
344 499
345 It has three distinct "modes": 500 It has three distinct "modes":
346 501
347 * absolute timer ($interval = $reschedule_cb = 0) 502 * absolute timer ($interval = $reschedule_cb = 0)
503
348 This time simply fires at the wallclock time $at and doesn't 504 This time simply fires at the wallclock time $at and doesn't
349 repeat. It will not adjust when a time jump occurs, that is, if 505 repeat. It will not adjust when a time jump occurs, that is, if
350 it is to be run at January 1st 2011 then it will run when the 506 it is to be run at January 1st 2011 then it will run when the
351 system time reaches or surpasses this time. 507 system time reaches or surpasses this time.
352 508
353 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 509 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
510
354 In this mode the watcher will always be scheduled to time out at 511 In this mode the watcher will always be scheduled to time out at
355 the next "$at + N * $interval" time (for some integer N) and 512 the next "$at + N * $interval" time (for some integer N) and
356 then repeat, regardless of any time jumps. 513 then repeat, regardless of any time jumps.
357 514
358 This can be used to create timers that do not drift with respect 515 This can be used to create timers that do not drift with respect
… …
367 Another way to think about it (for the mathematically inclined) 524 Another way to think about it (for the mathematically inclined)
368 is that EV::periodic will try to run the callback in this mode 525 is that EV::periodic will try to run the callback in this mode
369 at the next possible time where "$time = $at (mod $interval)", 526 at the next possible time where "$time = $at (mod $interval)",
370 regardless of any time jumps. 527 regardless of any time jumps.
371 528
372 * manual reschedule mode ($reschedule_cb = coderef) 529 * manual reschedule mode ($reschedule_cb = coderef)
530
373 In this mode $interval and $at are both being ignored. Instead, 531 In this mode $interval and $at are both being ignored. Instead,
374 each time the periodic watcher gets scheduled, the reschedule 532 each time the periodic watcher gets scheduled, the reschedule
375 callback ($reschedule_cb) will be called with the watcher as 533 callback ($reschedule_cb) will be called with the watcher as
376 first, and the current time as second argument. 534 first, and the current time as second argument.
377 535
378 *This callback MUST NOT stop or destroy this or any other 536 *This callback MUST NOT stop or destroy this or any other
537 periodic watcher, ever, and MUST NOT call any event loop
379 periodic watcher, ever*. If you need to stop it, return 1e30 and 538 functions or methods*. If you need to stop it, return 1e30 and
380 stop it afterwards. 539 stop it afterwards. You may create and start a "EV::prepare"
540 watcher for this task.
381 541
382 It must return the next time to trigger, based on the passed 542 It must return the next time to trigger, based on the passed
383 time value (that is, the lowest time value larger than to the 543 time value (that is, the lowest time value larger than or equal
384 second argument). It will usually be called just before the 544 to to the second argument). It will usually be called just
385 callback will be triggered, but might be called at other times, 545 before the callback will be triggered, but might be called at
386 too. 546 other times, too.
387 547
388 This can be used to create very complex timers, such as a timer 548 This can be used to create very complex timers, such as a timer
389 that triggers on each midnight, local time (actually 24 hours 549 that triggers on each midnight, local time (actually 24 hours
390 after the last midnight, to keep the example simple. If you know 550 after the last midnight, to keep the example simple. If you know
391 a way to do it correctly in about the same space (without 551 a way to do it correctly in about the same space (without
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409 be called at any time. 569 be called at any time.
410 570
411 $w->again 571 $w->again
412 Simply stops and starts the watcher again. 572 Simply stops and starts the watcher again.
413 573
574 $time = $w->at
575 Return the time that the watcher is expected to trigger next.
576
414 SIGNAL WATCHERS - signal me when a signal gets signalled! 577 SIGNAL WATCHERS - signal me when a signal gets signalled!
415 $w = EV::signal $signal, $callback 578 $w = EV::signal $signal, $callback
416 $w = EV::signal_ns $signal, $callback 579 $w = EV::signal_ns $signal, $callback
580 $w = $loop->signal ($signal, $callback)
581 $w = $loop->signal_ns ($signal, $callback)
417 Call the callback when $signal is received (the signal can be 582 Call the callback when $signal is received (the signal can be
418 specified by number or by name, just as with "kill" or %SIG). 583 specified by number or by name, just as with "kill" or %SIG).
584
585 Only one event loop can grab a given signal - attempting to grab the
586 same signal from two EV loops will crash the program immediately or
587 cause data corruption.
419 588
420 EV will grab the signal for the process (the kernel only allows one 589 EV will grab the signal for the process (the kernel only allows one
421 component to receive a signal at a time) when you start a signal 590 component to receive a signal at a time) when you start a signal
422 watcher, and removes it again when you stop it. Perl does the same 591 watcher, and removes it again when you stop it. Perl does the same
423 when you add/remove callbacks to %SIG, so watch out. 592 when you add/remove callbacks to %SIG, so watch out.
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435 $old_signum = $w->signal ($new_signal) 604 $old_signum = $w->signal ($new_signal)
436 Returns the previously set signal (always as a number not name) and 605 Returns the previously set signal (always as a number not name) and
437 optionally set a new one. 606 optionally set a new one.
438 607
439 CHILD WATCHERS - watch out for process status changes 608 CHILD WATCHERS - watch out for process status changes
440 $w = EV::child $pid, $callback 609 $w = EV::child $pid, $trace, $callback
441 $w = EV::child_ns $pid, $callback 610 $w = EV::child_ns $pid, $trace, $callback
611 $w = $loop->child ($pid, $trace, $callback)
612 $w = $loop->child_ns ($pid, $trace, $callback)
442 Call the callback when a status change for pid $pid (or any pid if 613 Call the callback when a status change for pid $pid (or any pid if
443 $pid is 0) has been received. More precisely: when the process 614 $pid is 0) has been received (a status change happens when the
615 process terminates or is killed, or, when trace is true,
616 additionally when it is stopped or continued). More precisely: when
444 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 617 the process receives a "SIGCHLD", EV will fetch the outstanding
445 for all changed/zombie children and call the callback. 618 exit/wait status for all changed/zombie children and call the
619 callback.
446 620
447 It is valid (and fully supported) to install a child watcher after a 621 It is valid (and fully supported) to install a child watcher after a
448 child has exited but before the event loop has started its next 622 child has exited but before the event loop has started its next
449 iteration (for example, first you "fork", then the new child process 623 iteration (for example, first you "fork", then the new child process
450 might exit, and only then do you install a child watcher in the 624 might exit, and only then do you install a child watcher in the
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457 be called. 631 be called.
458 632
459 The "child_ns" variant doesn't start (activate) the newly created 633 The "child_ns" variant doesn't start (activate) the newly created
460 watcher. 634 watcher.
461 635
462 $w->set ($pid) 636 $w->set ($pid, $trace)
463 Reconfigures the watcher, see the constructor above for details. Can 637 Reconfigures the watcher, see the constructor above for details. Can
464 be called at any time. 638 be called at any time.
465 639
466 $current_pid = $w->pid 640 $current_pid = $w->pid
467 $old_pid = $w->pid ($new_pid)
468 Returns the previously set process id and optionally set a new one. 641 Returns the previously set process id and optionally set a new one.
469 642
470 $exit_status = $w->rstatus 643 $exit_status = $w->rstatus
471 Return the exit/wait status (as returned by waitpid, see the waitpid 644 Return the exit/wait status (as returned by waitpid, see the waitpid
472 entry in perlfunc). 645 entry in perlfunc).
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476 a watcher for all pids). 649 a watcher for all pids).
477 650
478 STAT WATCHERS - did the file attributes just change? 651 STAT WATCHERS - did the file attributes just change?
479 $w = EV::stat $path, $interval, $callback 652 $w = EV::stat $path, $interval, $callback
480 $w = EV::stat_ns $path, $interval, $callback 653 $w = EV::stat_ns $path, $interval, $callback
654 $w = $loop->stat ($path, $interval, $callback)
655 $w = $loop->stat_ns ($path, $interval, $callback)
481 Call the callback when a file status change has been detected on 656 Call the callback when a file status change has been detected on
482 $path. The $path does not need to exist, changing from "path exists" 657 $path. The $path does not need to exist, changing from "path exists"
483 to "path does not exist" is a status change like any other. 658 to "path does not exist" is a status change like any other.
484 659
485 The $interval is a recommended polling interval for systems where 660 The $interval is a recommended polling interval for systems where
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545 Can be used to query the actual interval used. 720 Can be used to query the actual interval used.
546 721
547 IDLE WATCHERS - when you've got nothing better to do... 722 IDLE WATCHERS - when you've got nothing better to do...
548 $w = EV::idle $callback 723 $w = EV::idle $callback
549 $w = EV::idle_ns $callback 724 $w = EV::idle_ns $callback
725 $w = $loop->idle ($callback)
726 $w = $loop->idle_ns ($callback)
550 Call the callback when there are no other pending watchers of the 727 Call the callback when there are no other pending watchers of the
551 same or higher priority (excluding check, prepare and other idle 728 same or higher priority (excluding check, prepare and other idle
552 watchers of the same or lower priority, of course). They are called 729 watchers of the same or lower priority, of course). They are called
553 idle watchers because when the watcher is the highest priority 730 idle watchers because when the watcher is the highest priority
554 pending event in the process, the process is considered to be idle 731 pending event in the process, the process is considered to be idle
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570 watcher. 747 watcher.
571 748
572 PREPARE WATCHERS - customise your event loop! 749 PREPARE WATCHERS - customise your event loop!
573 $w = EV::prepare $callback 750 $w = EV::prepare $callback
574 $w = EV::prepare_ns $callback 751 $w = EV::prepare_ns $callback
752 $w = $loop->prepare ($callback)
753 $w = $loop->prepare_ns ($callback)
575 Call the callback just before the process would block. You can still 754 Call the callback just before the process would block. You can still
576 create/modify any watchers at this point. 755 create/modify any watchers at this point.
577 756
578 See the EV::check watcher, below, for explanations and an example. 757 See the EV::check watcher, below, for explanations and an example.
579 758
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581 watcher. 760 watcher.
582 761
583 CHECK WATCHERS - customise your event loop even more! 762 CHECK WATCHERS - customise your event loop even more!
584 $w = EV::check $callback 763 $w = EV::check $callback
585 $w = EV::check_ns $callback 764 $w = EV::check_ns $callback
765 $w = $loop->check ($callback)
766 $w = $loop->check_ns ($callback)
586 Call the callback just after the process wakes up again (after it 767 Call the callback just after the process wakes up again (after it
587 has gathered events), but before any other callbacks have been 768 has gathered events), but before any other callbacks have been
588 invoked. 769 invoked.
589 770
590 This is used to integrate other event-based software into the EV 771 This is used to integrate other event-based software into the EV
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626 # make the dispatcher handle any new stuff 807 # make the dispatcher handle any new stuff
627 ... not shown 808 ... not shown
628 }; 809 };
629 810
630 The callbacks of the created watchers will not be called as the 811 The callbacks of the created watchers will not be called as the
631 watchers are destroyed before this cna happen (remember EV::check 812 watchers are destroyed before this can happen (remember EV::check
632 gets called first). 813 gets called first).
633 814
634 The "check_ns" variant doesn't start (activate) the newly created 815 The "check_ns" variant doesn't start (activate) the newly created
635 watcher. 816 watcher.
636 817
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639 is done before the event loop blocks next and before "check" watchers 820 is done before the event loop blocks next and before "check" watchers
640 are being called, and only in the child after the fork. 821 are being called, and only in the child after the fork.
641 822
642 $w = EV::fork $callback 823 $w = EV::fork $callback
643 $w = EV::fork_ns $callback 824 $w = EV::fork_ns $callback
825 $w = $loop->fork ($callback)
826 $w = $loop->fork_ns ($callback)
644 Call the callback before the event loop is resumed in the child 827 Call the callback before the event loop is resumed in the child
645 process after a fork. 828 process after a fork.
646 829
647 The "fork_ns" variant doesn't start (activate) the newly created 830 The "fork_ns" variant doesn't start (activate) the newly created
648 watcher. 831 watcher.
832
833 EMBED WATCHERS - when one backend isn't enough...
834 This is a rather advanced watcher type that lets you embed one event
835 loop into another (currently only IO events are supported in the
836 embedded loop, other types of watchers might be handled in a delayed or
837 incorrect fashion and must not be used).
838
839 See the libev documentation at
840 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
841 _when_one_backend_> (locally installed as EV::libev) for more details.
842
843 In short, this watcher is most useful on BSD systems without working
844 kqueue to still be able to handle a large number of sockets:
845
846 my $socket_loop;
847
848 # check wether we use SELECT or POLL _and_ KQUEUE is supported
849 if (
850 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
851 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
852 ) {
853 # use kqueue for sockets
854 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
855 }
856
857 # use the default loop otherwise
858 $socket_loop ||= EV::default_loop;
859
860 $w = EV::embed $otherloop[, $callback]
861 $w = EV::embed_ns $otherloop[, $callback]
862 $w = $loop->embed ($otherloop[, $callback])
863 $w = $loop->embed_ns ($otherloop[, $callback])
864 Call the callback when the embedded event loop ($otherloop) has any
865 I/O activity. The $callback is optional: if it is missing, then the
866 embedded event loop will be managed automatically (which is
867 recommended), otherwise you have to invoke "sweep" yourself.
868
869 The "embed_ns" variant doesn't start (activate) the newly created
870 watcher.
871
872 ASYNC WATCHERS - how to wake up another event loop
873 Async watchers are provided by EV, but have little use in perl directly,
874 as perl neither supports threads running in parallel nor direct access
875 to signal handlers or other contexts where they could be of value.
876
877 It is, however, possible to use them from the XS level.
878
879 Please see the libev documentation for further details.
880
881 $w = EV::async $callback
882 $w = EV::async_ns $callback
883 $w->send
884 $bool = $w->async_pending
649 885
650PERL SIGNALS 886PERL SIGNALS
651 While Perl signal handling (%SIG) is not affected by EV, the behaviour 887 While Perl signal handling (%SIG) is not affected by EV, the behaviour
652 with EV is as the same as any other C library: Perl-signals will only be 888 with EV is as the same as any other C library: Perl-signals will only be
653 handled when Perl runs, which means your signal handler might be invoked 889 handled when Perl runs, which means your signal handler might be invoked
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660 to be called on every event loop iteration by installing a "EV::check" 896 to be called on every event loop iteration by installing a "EV::check"
661 watcher: 897 watcher:
662 898
663 my $async_check = EV::check sub { }; 899 my $async_check = EV::check sub { };
664 900
665 This ensures that perl shortly gets into control for a short time, and 901 This ensures that perl gets into control for a short time to handle any
666 also ensures slower overall operation. 902 pending signals, and also ensures (slightly) slower overall operation.
667 903
668THREADS 904ITHREADS
669 Threads are not supported by this module in any way. Perl pseudo-threads 905 Ithreads are not supported by this module in any way. Perl
670 is evil stuff and must die. As soon as Perl gains real threads I will 906 pseudo-threads is evil stuff and must die. Real threads as provided by
671 work on thread support for it. 907 Coro are fully supported (and enhanced support is available via
908 Coro::EV).
672 909
673FORK 910FORK
674 Most of the "improved" event delivering mechanisms of modern operating 911 Most of the "improved" event delivering mechanisms of modern operating
675 systems have quite a few problems with fork(2) (to put it bluntly: it is 912 systems have quite a few problems with fork(2) (to put it bluntly: it is
676 not supported and usually destructive). Libev makes it possible to work 913 not supported and usually destructive). Libev makes it possible to work
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686 923
687 On win32, there is no notion of fork so all this doesn't apply, of 924 On win32, there is no notion of fork so all this doesn't apply, of
688 course. 925 course.
689 926
690SEE ALSO 927SEE ALSO
691 EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event 928 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
692 loop), Coro::EV (efficient coroutines with EV). 929 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
930 with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop
931 agnostic and portable event driven programming.
693 932
694AUTHOR 933AUTHOR
695 Marc Lehmann <schmorp@schmorp.de> 934 Marc Lehmann <schmorp@schmorp.de>
696 http://home.schmorp.de/ 935 http://home.schmorp.de/
697 936

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