ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/EV/README
(Generate patch)

Comparing EV/README (file contents):
Revision 1.18 by root, Tue Dec 11 21:18:25 2007 UTC vs.
Revision 1.32 by root, Tue Apr 28 00:50:57 2009 UTC

1NAME 1NAME
2 EV - perl interface to libev, a high performance full-featured event 2 EV - perl interface to libev, a high performance full-featured event
3 loop 3 loop
4 4
5SYNOPSIS 5SYNOPSIS
6 use EV; 6 use EV;
7 7
8 # TIMERS 8 # TIMERS
9 9
10 my $w = EV::timer 2, 0, sub { 10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s"; 11 warn "is called after 2s";
12 }; 12 };
13 13
14 my $w = EV::timer 2, 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 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 54
55DESCRIPTION 55DESCRIPTION
56 This module provides an interface to libev 56 This module provides an interface to libev
57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation 57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
58 below is comprehensive, one might also consult the documentation of 58 below is comprehensive, one might also consult the documentation of
59 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
60 details on watcher semantics or some discussion on the available 60 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 61 discussion on the available backends, or how to force a specific backend
62 about in any case because it has much more detailed information. 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.
63 128
64BASIC INTERFACE 129BASIC INTERFACE
65 $EV::DIED 130 $EV::DIED
66 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
67 callback throws an exception (with $@ containing the error). The 132 callback throws an exception (with $@ containing the error). The
68 default prints an informative message and continues. 133 default prints an informative message and continues.
69 134
70 If this callback throws an exception it will be silently ignored. 135 If this callback throws an exception it will be silently ignored.
71 136
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.
147
72 $time = EV::time 148 $time = EV::time
73 Returns the current time in (fractional) seconds since the epoch. 149 Returns the current time in (fractional) seconds since the epoch.
74 150
75 $time = EV::now 151 $time = EV::now
152 $time = $loop->now
76 Returns the time the last event loop iteration has been started. 153 Returns the time the last event loop iteration has been started.
77 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
78 to it is usually faster then calling EV::time. 155 to it is usually faster then calling EV::time.
79 156
80 $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 = $loop->backend
81 Returns an integer describing the backend used by libev 196 Returns an integer describing the backend used by libev
82 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 197 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
83 198
84 EV::loop [$flags] 199 EV::loop [$flags]
200 $loop->loop ([$flags])
85 Begin checking for events and calling callbacks. It returns when a 201 Begin checking for events and calling callbacks. It returns when a
86 callback calls EV::unloop. 202 callback calls EV::unloop.
87 203
88 The $flags argument can be one of the following: 204 The $flags argument can be one of the following:
89 205
90 0 as above 206 0 as above
91 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 207 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
92 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 208 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
93 209
94 EV::unloop [$how] 210 EV::unloop [$how]
211 $loop->unloop ([$how])
95 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,
96 makes the innermost call to EV::loop return. 213 makes the innermost call to EV::loop return.
97 214
98 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
99 EV::loop will return as fast as possible. 216 EV::loop will return as fast as possible.
100 217
101 $count = EV::loop_count 218 $count = EV::loop_count
219 $count = $loop->loop_count
102 Return the number of times the event loop has polled for new events. 220 Return the number of times the event loop has polled for new events.
103 Sometiems useful as a generation counter. 221 Sometimes useful as a generation counter.
104 222
105 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))
106 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
107 one-shot event without the need for managing a watcher object. 226 one-shot event without the need for managing a watcher object.
108 227
109 If $fh_or_undef is a filehandle or file descriptor, then $events 228 If $fh_or_undef is a filehandle or file descriptor, then $events
110 must be a bitset containing either "EV::READ", "EV::WRITE" or 229 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
115 If timeout is "undef" or negative, then there will be no timeout. 234 If timeout is "undef" or negative, then there will be no timeout.
116 Otherwise a EV::timer with this value will be started. 235 Otherwise a EV::timer with this value will be started.
117 236
118 When an error occurs or either the timeout or I/O watcher triggers, 237 When an error occurs or either the timeout or I/O watcher triggers,
119 then the callback will be called with the received event set (in 238 then the callback will be called with the received event set (in
120 general you can expect it to be a combination of "EV:ERROR", 239 general you can expect it to be a combination of "EV::ERROR",
121 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 240 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
122 241
123 EV::once doesn't return anything: the watchers stay active till 242 EV::once doesn't return anything: the watchers stay active till
124 either of them triggers, then they will be stopped and freed, and 243 either of them triggers, then they will be stopped and freed, and
125 the callback invoked. 244 the callback invoked.
126 245
127 EV::feed_fd_event ($fd, $revents) 246 EV::feed_fd_event ($fd, $revents)
247 $loop->feed_fd_event ($fd, $revents)
128 Feed an event on a file descriptor into EV. EV will react to this 248 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 249 call as if the readyness notifications specified by $revents (a
130 combination of "EV::READ" and "EV::WRITE") happened on the file 250 combination of "EV::READ" and "EV::WRITE") happened on the file
131 descriptor $fd. 251 descriptor $fd.
132 252
133 EV::feed_signal_event ($signal) 253 EV::feed_signal_event ($signal)
134 Feed a signal event into EV. EV will react to this call as if the 254 Feed a signal event into EV. EV will react to this call as if the
135 signal specified by $signal had occured. 255 signal specified by $signal had occured.
136 256
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
137 WATCHER OBJECTS 268WATCHER OBJECTS
138 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
139 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,
140 you would create an EV::io watcher for that: 271 you would create an EV::io watcher for that:
141 272
142 my $watcher = EV::io *STDIN, EV::READ, sub { 273 my $watcher = EV::io *STDIN, EV::READ, sub {
143 my ($watcher, $revents) = @_; 274 my ($watcher, $revents) = @_;
144 warn "yeah, STDIN should not be readable without blocking!\n" 275 warn "yeah, STDIN should now be readable without blocking!\n"
145 }; 276 };
146 277
147 All watchers can be active (waiting for events) or inactive (paused). 278 All watchers can be active (waiting for events) or inactive (paused).
148 Only active watchers will have their callbacks invoked. All callbacks 279 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 280 will be called with at least two arguments: the watcher and a bitmask of
150 received events. 281 received events.
151 282
152 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
153 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
154 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,
155 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O 286 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 287 events (which can set both EV::READ and EV::WRITE bits), and EV::timer
157 (which uses EV::TIMEOUT). 288 (which uses EV::TIMEOUT).
158 289
159 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
… …
220 $w->feed_event ($revents) 351 $w->feed_event ($revents)
221 Feed some events on this watcher into EV. EV will react to this call 352 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. 353 as if the watcher had received the given $revents mask.
223 354
224 $revents = $w->clear_pending 355 $revents = $w->clear_pending
225 If the watcher is pending, this function returns clears its pending 356 If the watcher is pending, this function clears its pending status
226 status and returns its $revents bitset (as if its callback was 357 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 358 the watcher isn't pending it does nothing and returns 0.
228 0.
229 359
230 $previous_state = $w->keepalive ($bool) 360 $previous_state = $w->keepalive ($bool)
231 Normally, "EV::loop" will return when there are no active watchers 361 Normally, "EV::loop" will return when there are no active watchers
232 (which is a "deadlock" because no progress can be made anymore). 362 (which is a "deadlock" because no progress can be made anymore).
233 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
234 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
235 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
236 for their task :). 366 for their task :).
237 367
238 Sometimes, however, this gets in your way, for example when you the 368 Sometimes, however, this gets in your way, for example when the
239 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
240 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
241 module written by somebody else even). Then you might want any 371 module written by somebody else even). Then you might want any
242 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
243 "EV::loop" from returning just because you happen to have this 373 "EV::loop" from returning just because you happen to have this
… …
245 375
246 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
247 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
248 returning. 378 returning.
249 379
250 The initial value for keepalive is true (enabled), and you cna 380 The initial value for keepalive is true (enabled), and you can
251 change it any time. 381 change it any time.
252 382
253 Example: Register an I/O watcher for some UDP socket but do not keep 383 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. 384 the event loop from running just because of that watcher.
255 385
256 my $udp_socket = ... 386 my $udp_socket = ...
257 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 387 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
258 $udp_watcher->keepalive (0); 388 $udp_watcher->keepalive (0);
259 389
390 $loop = $w->loop
391 Return the loop that this watcher is attached to.
392
260 WATCHER TYPES 393WATCHER TYPES
261 Each of the following subsections describes a single watcher type. 394 Each of the following subsections describes a single watcher type.
262 395
263 I/O WATCHERS - is this file descriptor readable or writable? 396 I/O WATCHERS - is this file descriptor readable or writable?
264 $w = EV::io $fileno_or_fh, $eventmask, $callback 397 $w = EV::io $fileno_or_fh, $eventmask, $callback
265 $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)
266 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
267 when at least one of events specified in $eventmask occurs. 402 when at least one of events specified in $eventmask occurs.
268 403
269 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:
270 405
… …
287 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.
288 423
289 TIMER WATCHERS - relative and optionally repeating timeouts 424 TIMER WATCHERS - relative and optionally repeating timeouts
290 $w = EV::timer $after, $repeat, $callback 425 $w = EV::timer $after, $repeat, $callback
291 $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)
292 Calls the callback after $after seconds (which may be fractional). 429 Calls the callback after $after seconds (which may be fractional).
293 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
294 $repeat value as $after) after the callback returns. 431 $repeat value as $after) after the callback returns.
295 432
296 This means that the callback would be called roughly after $after 433 This means that the callback would be called roughly after $after
… …
332 method on the timeout. 469 method on the timeout.
333 470
334 PERIODIC WATCHERS - to cron or not to cron? 471 PERIODIC WATCHERS - to cron or not to cron?
335 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 472 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
336 $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, $callback)
337 Similar to EV::timer, but is not based on relative timeouts but on 476 Similar to EV::timer, but is not based on relative timeouts but on
338 absolute times. Apart from creating "simple" timers that trigger 477 absolute times. Apart from creating "simple" timers that trigger
339 "at" the specified time, it can also be used for non-drifting 478 "at" the specified time, it can also be used for non-drifting
340 absolute timers and more complex, cron-like, setups that are not 479 absolute timers and more complex, cron-like, setups that are not
341 adversely affected by time jumps (i.e. when the system clock is 480 adversely affected by time jumps (i.e. when the system clock is
342 changed by explicit date -s or other means such as ntpd). It is also 481 changed by explicit date -s or other means such as ntpd). It is also
343 the most complex watcher type in EV. 482 the most complex watcher type in EV.
344 483
345 It has three distinct "modes": 484 It has three distinct "modes":
346 485
347 * absolute timer ($interval = $reschedule_cb = 0) 486 * absolute timer ($interval = $reschedule_cb = 0)
487
348 This time simply fires at the wallclock time $at and doesn't 488 This time simply fires at the wallclock time $at and doesn't
349 repeat. It will not adjust when a time jump occurs, that is, if 489 repeat. It will not adjust when a time jump occurs, that is, if
350 it is to be run at January 1st 2011 then it will run when the 490 it is to be run at January 1st 2011 then it will run when the
351 system time reaches or surpasses this time. 491 system time reaches or surpasses this time.
352 492
353 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 493 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
494
354 In this mode the watcher will always be scheduled to time out at 495 In this mode the watcher will always be scheduled to time out at
355 the next "$at + N * $interval" time (for some integer N) and 496 the next "$at + N * $interval" time (for some integer N) and
356 then repeat, regardless of any time jumps. 497 then repeat, regardless of any time jumps.
357 498
358 This can be used to create timers that do not drift with respect 499 This can be used to create timers that do not drift with respect
… …
367 Another way to think about it (for the mathematically inclined) 508 Another way to think about it (for the mathematically inclined)
368 is that EV::periodic will try to run the callback in this mode 509 is that EV::periodic will try to run the callback in this mode
369 at the next possible time where "$time = $at (mod $interval)", 510 at the next possible time where "$time = $at (mod $interval)",
370 regardless of any time jumps. 511 regardless of any time jumps.
371 512
372 * manual reschedule mode ($reschedule_cb = coderef) 513 * manual reschedule mode ($reschedule_cb = coderef)
514
373 In this mode $interval and $at are both being ignored. Instead, 515 In this mode $interval and $at are both being ignored. Instead,
374 each time the periodic watcher gets scheduled, the reschedule 516 each time the periodic watcher gets scheduled, the reschedule
375 callback ($reschedule_cb) will be called with the watcher as 517 callback ($reschedule_cb) will be called with the watcher as
376 first, and the current time as second argument. 518 first, and the current time as second argument.
377 519
378 *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
379 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
380 stop it afterwards. 523 stop it afterwards. You may create and start a "EV::prepare"
524 watcher for this task.
381 525
382 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
383 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
384 second argument). It will usually be called just before the 528 to to the second argument). It will usually be called just
385 callback will be triggered, but might be called at other times, 529 before the callback will be triggered, but might be called at
386 too. 530 other times, too.
387 531
388 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
389 that triggers on each midnight, local time (actually 24 hours 533 that triggers on each midnight, local time (actually 24 hours
390 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
391 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
… …
409 be called at any time. 553 be called at any time.
410 554
411 $w->again 555 $w->again
412 Simply stops and starts the watcher again. 556 Simply stops and starts the watcher again.
413 557
558 $time = $w->at
559 Return the time that the watcher is expected to trigger next.
560
414 SIGNAL WATCHERS - signal me when a signal gets signalled! 561 SIGNAL WATCHERS - signal me when a signal gets signalled!
415 $w = EV::signal $signal, $callback 562 $w = EV::signal $signal, $callback
416 $w = EV::signal_ns $signal, $callback 563 $w = EV::signal_ns $signal, $callback
417 Call the callback when $signal is received (the signal can be 564 Call the callback when $signal is received (the signal can be
418 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).
… …
435 $old_signum = $w->signal ($new_signal) 582 $old_signum = $w->signal ($new_signal)
436 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
437 optionally set a new one. 584 optionally set a new one.
438 585
439 CHILD WATCHERS - watch out for process status changes 586 CHILD WATCHERS - watch out for process status changes
440 $w = EV::child $pid, $callback 587 $w = EV::child $pid, $trace, $callback
441 $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)
442 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
443 $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
444 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 595 the process receives a "SIGCHLD", EV will fetch the outstanding
445 for all changed/zombie children and call the callback. 596 exit/wait status for all changed/zombie children and call the
597 callback.
446 598
447 It is valid (and fully supported) to install a child watcher after a 599 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 600 child has exited but before the event loop has started its next
449 iteration (for example, first you "fork", then the new child process 601 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 602 might exit, and only then do you install a child watcher in the
… …
457 be called. 609 be called.
458 610
459 The "child_ns" variant doesn't start (activate) the newly created 611 The "child_ns" variant doesn't start (activate) the newly created
460 watcher. 612 watcher.
461 613
462 $w->set ($pid) 614 $w->set ($pid, $trace)
463 Reconfigures the watcher, see the constructor above for details. Can 615 Reconfigures the watcher, see the constructor above for details. Can
464 be called at any time. 616 be called at any time.
465 617
466 $current_pid = $w->pid 618 $current_pid = $w->pid
467 $old_pid = $w->pid ($new_pid)
468 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.
469 620
470 $exit_status = $w->rstatus 621 $exit_status = $w->rstatus
471 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
472 entry in perlfunc). 623 entry in perlfunc).
… …
476 a watcher for all pids). 627 a watcher for all pids).
477 628
478 STAT WATCHERS - did the file attributes just change? 629 STAT WATCHERS - did the file attributes just change?
479 $w = EV::stat $path, $interval, $callback 630 $w = EV::stat $path, $interval, $callback
480 $w = EV::stat_ns $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)
481 Call the callback when a file status change has been detected on 634 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" 635 $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. 636 to "path does not exist" is a status change like any other.
484 637
485 The $interval is a recommended polling interval for systems where 638 The $interval is a recommended polling interval for systems where
… …
545 Can be used to query the actual interval used. 698 Can be used to query the actual interval used.
546 699
547 IDLE WATCHERS - when you've got nothing better to do... 700 IDLE WATCHERS - when you've got nothing better to do...
548 $w = EV::idle $callback 701 $w = EV::idle $callback
549 $w = EV::idle_ns $callback 702 $w = EV::idle_ns $callback
703 $w = $loop->idle ($callback)
704 $w = $loop->idle_ns ($callback)
550 Call the callback when there are no other pending watchers of the 705 Call the callback when there are no other pending watchers of the
551 same or higher priority (excluding check, prepare and other idle 706 same or higher priority (excluding check, prepare and other idle
552 watchers of the same or lower priority, of course). They are called 707 watchers of the same or lower priority, of course). They are called
553 idle watchers because when the watcher is the highest priority 708 idle watchers because when the watcher is the highest priority
554 pending event in the process, the process is considered to be idle 709 pending event in the process, the process is considered to be idle
… …
570 watcher. 725 watcher.
571 726
572 PREPARE WATCHERS - customise your event loop! 727 PREPARE WATCHERS - customise your event loop!
573 $w = EV::prepare $callback 728 $w = EV::prepare $callback
574 $w = EV::prepare_ns $callback 729 $w = EV::prepare_ns $callback
730 $w = $loop->prepare ($callback)
731 $w = $loop->prepare_ns ($callback)
575 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
576 create/modify any watchers at this point. 733 create/modify any watchers at this point.
577 734
578 See the EV::check watcher, below, for explanations and an example. 735 See the EV::check watcher, below, for explanations and an example.
579 736
… …
581 watcher. 738 watcher.
582 739
583 CHECK WATCHERS - customise your event loop even more! 740 CHECK WATCHERS - customise your event loop even more!
584 $w = EV::check $callback 741 $w = EV::check $callback
585 $w = EV::check_ns $callback 742 $w = EV::check_ns $callback
743 $w = $loop->check ($callback)
744 $w = $loop->check_ns ($callback)
586 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
587 has gathered events), but before any other callbacks have been 746 has gathered events), but before any other callbacks have been
588 invoked. 747 invoked.
589 748
590 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
… …
626 # make the dispatcher handle any new stuff 785 # make the dispatcher handle any new stuff
627 ... not shown 786 ... not shown
628 }; 787 };
629 788
630 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
631 watchers are destroyed before this cna happen (remember EV::check 790 watchers are destroyed before this can happen (remember EV::check
632 gets called first). 791 gets called first).
633 792
634 The "check_ns" variant doesn't start (activate) the newly created 793 The "check_ns" variant doesn't start (activate) the newly created
635 watcher. 794 watcher.
636 795
… …
639 is done before the event loop blocks next and before "check" watchers 798 is done before the event loop blocks next and before "check" watchers
640 are being called, and only in the child after the fork. 799 are being called, and only in the child after the fork.
641 800
642 $w = EV::fork $callback 801 $w = EV::fork $callback
643 $w = EV::fork_ns $callback 802 $w = EV::fork_ns $callback
803 $w = $loop->fork ($callback)
804 $w = $loop->fork_ns ($callback)
644 Call the callback before the event loop is resumed in the child 805 Call the callback before the event loop is resumed in the child
645 process after a fork. 806 process after a fork.
646 807
647 The "fork_ns" variant doesn't start (activate) the newly created 808 The "fork_ns" variant doesn't start (activate) the newly created
648 watcher. 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
649 863
650PERL SIGNALS 864PERL SIGNALS
651 While Perl signal handling (%SIG) is not affected by EV, the behaviour 865 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 866 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 867 handled when Perl runs, which means your signal handler might be invoked
… …
660 to be called on every event loop iteration by installing a "EV::check" 874 to be called on every event loop iteration by installing a "EV::check"
661 watcher: 875 watcher:
662 876
663 my $async_check = EV::check sub { }; 877 my $async_check = EV::check sub { };
664 878
665 This ensures that perl shortly gets into control for a short time, and 879 This ensures that perl gets into control for a short time to handle any
666 also ensures slower overall operation. 880 pending signals, and also ensures (slightly) slower overall operation.
667 881
668THREADS 882THREADS
669 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
670 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
671 work on thread support for it. 885 work on thread support for it.
… …
686 900
687 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
688 course. 902 course.
689 903
690SEE ALSO 904SEE ALSO
691 EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event 905 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
692 loop), Coro::EV (efficient coroutines with EV). 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.
693 909
694AUTHOR 910AUTHOR
695 Marc Lehmann <schmorp@schmorp.de> 911 Marc Lehmann <schmorp@schmorp.de>
696 http://home.schmorp.de/ 912 http://home.schmorp.de/
697 913

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines