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Revision 1.19 by root, Tue Dec 18 01:37:46 2007 UTC vs.
Revision 1.20 by root, Sat Dec 22 12:05:42 2007 UTC

59 libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle 59 libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle
60 details on watcher semantics or some discussion on the available 60 details on watcher semantics or some discussion on the available
61 backends, or how to force a specific backend with "LIBEV_FLAGS", or just 61 backends, or how to force a specific backend with "LIBEV_FLAGS", or just
62 about in any case because it has much more detailed information. 62 about in any case because it has much more detailed information.
63 63
64EVENT LOOPS
65 EV supports multiple event loops: There is a single "default event loop"
66 that can handle everything including signals and child watchers, and any
67 number of "dynamic event loops" that can use different backends (with
68 various limitations), but no child and signal watchers.
69
70 You do not have to do anything to create the default event loop: When
71 the module is loaded a suitable backend is selected on the premise of
72 selecting a working backend (which for example rules out kqueue on most
73 BSDs). Modules should, unless they have "special needs" always use the
74 default loop as this is fastest (perl-wise), best supported by other
75 modules (e.g. AnyEvent or Coro) and most portable event loop.
76
77 For specific programs you cna create additional event loops dynamically.
78
79 $loop = new EV::loop [$flags]
80 Create a new event loop as per the specified flags. Please refer to
81 the "ev_loop_new ()" function description in the libev documentation
82 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
83 ONS>) for more info.
84
85 The loop will automatically be destroyed when it is no longer
86 referenced by any watcher and the loop object goes out of scope.
87
88 Using "EV::FLAG_FORKCHECK" is recommended, as only the default event
89 loop is protected by this module.
90
91 $loop->loop_fork
92 Must be called after a fork in the child, before entering or
93 continuing the event loop. An alternative is to use
94 "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at
95 some performance loss (refer to the libev documentation).
96
64BASIC INTERFACE 97BASIC INTERFACE
65 $EV::DIED 98 $EV::DIED
66 Must contain a reference to a function that is called when a 99 Must contain a reference to a function that is called when a
67 callback throws an exception (with $@ containing the error). The 100 callback throws an exception (with $@ containing the error). The
68 default prints an informative message and continues. 101 default prints an informative message and continues.
71 104
72 $time = EV::time 105 $time = EV::time
73 Returns the current time in (fractional) seconds since the epoch. 106 Returns the current time in (fractional) seconds since the epoch.
74 107
75 $time = EV::now 108 $time = EV::now
109 $time = $loop->now
76 Returns the time the last event loop iteration has been started. 110 Returns the time the last event loop iteration has been started.
77 This is the time that (relative) timers are based on, and refering 111 This is the time that (relative) timers are based on, and refering
78 to it is usually faster then calling EV::time. 112 to it is usually faster then calling EV::time.
79 113
80 $method = EV::method 114 $backend = EV::backend
115 $backend = $loop->backend
81 Returns an integer describing the backend used by libev 116 Returns an integer describing the backend used by libev
82 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 117 (EV::METHOD_SELECT or EV::METHOD_EPOLL).
83 118
84 EV::loop [$flags] 119 EV::loop [$flags]
120 $loop->loop ([$flags])
85 Begin checking for events and calling callbacks. It returns when a 121 Begin checking for events and calling callbacks. It returns when a
86 callback calls EV::unloop. 122 callback calls EV::unloop.
87 123
88 The $flags argument can be one of the following: 124 The $flags argument can be one of the following:
89 125
90 0 as above 126 0 as above
91 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 127 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
92 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 128 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
93 129
94 EV::unloop [$how] 130 EV::unloop [$how]
131 $loop->unloop ([$how])
95 When called with no arguments or an argument of EV::UNLOOP_ONE, 132 When called with no arguments or an argument of EV::UNLOOP_ONE,
96 makes the innermost call to EV::loop return. 133 makes the innermost call to EV::loop return.
97 134
98 When called with an argument of EV::UNLOOP_ALL, all calls to 135 When called with an argument of EV::UNLOOP_ALL, all calls to
99 EV::loop will return as fast as possible. 136 EV::loop will return as fast as possible.
100 137
101 $count = EV::loop_count 138 $count = EV::loop_count
139 $count = $loop->loop_count
102 Return the number of times the event loop has polled for new events. 140 Return the number of times the event loop has polled for new events.
103 Sometiems useful as a generation counter. 141 Sometiems useful as a generation counter.
104 142
105 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 143 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
144 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
106 This function rolls together an I/O and a timer watcher for a single 145 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. 146 one-shot event without the need for managing a watcher object.
108 147
109 If $fh_or_undef is a filehandle or file descriptor, then $events 148 If $fh_or_undef is a filehandle or file descriptor, then $events
110 must be a bitset containing either "EV::READ", "EV::WRITE" or 149 must be a bitset containing either "EV::READ", "EV::WRITE" or
115 If timeout is "undef" or negative, then there will be no timeout. 154 If timeout is "undef" or negative, then there will be no timeout.
116 Otherwise a EV::timer with this value will be started. 155 Otherwise a EV::timer with this value will be started.
117 156
118 When an error occurs or either the timeout or I/O watcher triggers, 157 When an error occurs or either the timeout or I/O watcher triggers,
119 then the callback will be called with the received event set (in 158 then the callback will be called with the received event set (in
120 general you can expect it to be a combination of "EV:ERROR", 159 general you can expect it to be a combination of "EV::ERROR",
121 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 160 "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
122 161
123 EV::once doesn't return anything: the watchers stay active till 162 EV::once doesn't return anything: the watchers stay active till
124 either of them triggers, then they will be stopped and freed, and 163 either of them triggers, then they will be stopped and freed, and
125 the callback invoked. 164 the callback invoked.
126 165
127 EV::feed_fd_event ($fd, $revents) 166 EV::feed_fd_event ($fd, $revents)
167 $loop->feed_fd_event ($fd, $revents)
128 Feed an event on a file descriptor into EV. EV will react to this 168 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 169 call as if the readyness notifications specified by $revents (a
130 combination of "EV::READ" and "EV::WRITE") happened on the file 170 combination of "EV::READ" and "EV::WRITE") happened on the file
131 descriptor $fd. 171 descriptor $fd.
132 172
133 EV::feed_signal_event ($signal) 173 EV::feed_signal_event ($signal)
134 Feed a signal event into EV. EV will react to this call as if the 174 Feed a signal event into EV. EV will react to this call as if the
135 signal specified by $signal had occured. 175 signal specified by $signal had occured.
136 176
137 WATCHER OBJECTS 177WATCHER OBJECTS
138 A watcher is an object that gets created to record your interest in some 178 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, 179 event. For instance, if you want to wait for STDIN to become readable,
140 you would create an EV::io watcher for that: 180 you would create an EV::io watcher for that:
141 181
142 my $watcher = EV::io *STDIN, EV::READ, sub { 182 my $watcher = EV::io *STDIN, EV::READ, sub {
143 my ($watcher, $revents) = @_; 183 my ($watcher, $revents) = @_;
144 warn "yeah, STDIN should not be readable without blocking!\n" 184 warn "yeah, STDIN should now be readable without blocking!\n"
145 }; 185 };
146 186
147 All watchers can be active (waiting for events) or inactive (paused). 187 All watchers can be active (waiting for events) or inactive (paused).
148 Only active watchers will have their callbacks invoked. All callbacks 188 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 189 will be called with at least two arguments: the watcher and a bitmask of
220 $w->feed_event ($revents) 260 $w->feed_event ($revents)
221 Feed some events on this watcher into EV. EV will react to this call 261 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. 262 as if the watcher had received the given $revents mask.
223 263
224 $revents = $w->clear_pending 264 $revents = $w->clear_pending
225 If the watcher is pending, this function returns clears its pending 265 If the watcher is pending, this function clears its pending status
226 status and returns its $revents bitset (as if its callback was 266 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 267 the watcher isn't pending it does nothing and returns 0.
228 0.
229 268
230 $previous_state = $w->keepalive ($bool) 269 $previous_state = $w->keepalive ($bool)
231 Normally, "EV::loop" will return when there are no active watchers 270 Normally, "EV::loop" will return when there are no active watchers
232 (which is a "deadlock" because no progress can be made anymore). 271 (which is a "deadlock" because no progress can be made anymore).
233 This is convinient because it allows you to start your watchers (and 272 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 273 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 274 all your jobs are finished (or they forgot to register some watchers
236 for their task :). 275 for their task :).
237 276
238 Sometimes, however, this gets in your way, for example when you the 277 Sometimes, however, this gets in your way, for example when the
239 module that calls "EV::loop" (usually the main program) is not the 278 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 279 same module as a long-living watcher (for example a DNS client
241 module written by somebody else even). Then you might want any 280 module written by somebody else even). Then you might want any
242 outstanding requests to be handled, but you would not want to keep 281 outstanding requests to be handled, but you would not want to keep
243 "EV::loop" from returning just because you happen to have this 282 "EV::loop" from returning just because you happen to have this
253 Example: Register an I/O watcher for some UDP socket but do not keep 292 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. 293 the event loop from running just because of that watcher.
255 294
256 my $udp_socket = ... 295 my $udp_socket = ...
257 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 296 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
258 $udp_watcher->keepalive (0); 297 $1000udp_watcher->keepalive (0);
259 298
299 $loop = $w->loop
300 Return the loop that this watcher is attached to.
301
260 WATCHER TYPES 302WATCHER TYPES
261 Each of the following subsections describes a single watcher type. 303 Each of the following subsections describes a single watcher type.
262 304
263 I/O WATCHERS - is this file descriptor readable or writable? 305 I/O WATCHERS - is this file descriptor readable or writable?
264 $w = EV::io $fileno_or_fh, $eventmask, $callback 306 $w = EV::io $fileno_or_fh, $eventmask, $callback
265 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 307 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
308 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
309 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
266 As long as the returned watcher object is alive, call the $callback 310 As long as the returned watcher object is alive, call the $callback
267 when at least one of events specified in $eventmask occurs. 311 when at least one of events specified in $eventmask occurs.
268 312
269 The $eventmask can be one or more of these constants ORed together: 313 The $eventmask can be one or more of these constants ORed together:
270 314
287 Returns the previously set event mask and optionally set a new one. 331 Returns the previously set event mask and optionally set a new one.
288 332
289 TIMER WATCHERS - relative and optionally repeating timeouts 333 TIMER WATCHERS - relative and optionally repeating timeouts
290 $w = EV::timer $after, $repeat, $callback 334 $w = EV::timer $after, $repeat, $callback
291 $w = EV::timer_ns $after, $repeat, $callback 335 $w = EV::timer_ns $after, $repeat, $callback
336 $w = $loop->timer ($after, $repeat, $callback)
337 $w = $loop->timer_ns ($after, $repeat, $callback)
292 Calls the callback after $after seconds (which may be fractional). 338 Calls the callback after $after seconds (which may be fractional).
293 If $repeat is non-zero, the timer will be restarted (with the 339 If $repeat is non-zero, the timer will be restarted (with the
294 $repeat value as $after) after the callback returns. 340 $repeat value as $after) after the callback returns.
295 341
296 This means that the callback would be called roughly after $after 342 This means that the callback would be called roughly after $after
332 method on the timeout. 378 method on the timeout.
333 379
334 PERIODIC WATCHERS - to cron or not to cron? 380 PERIODIC WATCHERS - to cron or not to cron?
335 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 381 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
336 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 382 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
383 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
384 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
337 Similar to EV::timer, but is not based on relative timeouts but on 385 Similar to EV::timer, but is not based on relative timeouts but on
338 absolute times. Apart from creating "simple" timers that trigger 386 absolute times. Apart from creating "simple" timers that trigger
339 "at" the specified time, it can also be used for non-drifting 387 "at" the specified time, it can also be used for non-drifting
340 absolute timers and more complex, cron-like, setups that are not 388 absolute timers and more complex, cron-like, setups that are not
341 adversely affected by time jumps (i.e. when the system clock is 389 adversely affected by time jumps (i.e. when the system clock is
440 optionally set a new one. 488 optionally set a new one.
441 489
442 CHILD WATCHERS - watch out for process status changes 490 CHILD WATCHERS - watch out for process status changes
443 $w = EV::child $pid, $callback 491 $w = EV::child $pid, $callback
444 $w = EV::child_ns $pid, $callback 492 $w = EV::child_ns $pid, $callback
493 $w = $loop->child ($pid, $callback)
494 $w = $loop->child_ns ($pid, $callback)
445 Call the callback when a status change for pid $pid (or any pid if 495 Call the callback when a status change for pid $pid (or any pid if
446 $pid is 0) has been received. More precisely: when the process 496 $pid is 0) has been received. More precisely: when the process
447 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 497 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status
448 for all changed/zombie children and call the callback. 498 for all changed/zombie children and call the callback.
449 499
479 a watcher for all pids). 529 a watcher for all pids).
480 530
481 STAT WATCHERS - did the file attributes just change? 531 STAT WATCHERS - did the file attributes just change?
482 $w = EV::stat $path, $interval, $callback 532 $w = EV::stat $path, $interval, $callback
483 $w = EV::stat_ns $path, $interval, $callback 533 $w = EV::stat_ns $path, $interval, $callback
534 $w = $loop->stat ($path, $interval, $callback)
535 $w = $loop->stat_ns ($path, $interval, $callback)
484 Call the callback when a file status change has been detected on 536 Call the callback when a file status change has been detected on
485 $path. The $path does not need to exist, changing from "path exists" 537 $path. The $path does not need to exist, changing from "path exists"
486 to "path does not exist" is a status change like any other. 538 to "path does not exist" is a status change like any other.
487 539
488 The $interval is a recommended polling interval for systems where 540 The $interval is a recommended polling interval for systems where
548 Can be used to query the actual interval used. 600 Can be used to query the actual interval used.
549 601
550 IDLE WATCHERS - when you've got nothing better to do... 602 IDLE WATCHERS - when you've got nothing better to do...
551 $w = EV::idle $callback 603 $w = EV::idle $callback
552 $w = EV::idle_ns $callback 604 $w = EV::idle_ns $callback
605 $w = $loop->idle ($callback)
606 $w = $loop->idle_ns ($callback)
553 Call the callback when there are no other pending watchers of the 607 Call the callback when there are no other pending watchers of the
554 same or higher priority (excluding check, prepare and other idle 608 same or higher priority (excluding check, prepare and other idle
555 watchers of the same or lower priority, of course). They are called 609 watchers of the same or lower priority, of course). They are called
556 idle watchers because when the watcher is the highest priority 610 idle watchers because when the watcher is the highest priority
557 pending event in the process, the process is considered to be idle 611 pending event in the process, the process is considered to be idle
573 watcher. 627 watcher.
574 628
575 PREPARE WATCHERS - customise your event loop! 629 PREPARE WATCHERS - customise your event loop!
576 $w = EV::prepare $callback 630 $w = EV::prepare $callback
577 $w = EV::prepare_ns $callback 631 $w = EV::prepare_ns $callback
632 $w = $loop->prepare ($callback)
633 $w = $loop->prepare_ns ($callback)
578 Call the callback just before the process would block. You can still 634 Call the callback just before the process would block. You can still
579 create/modify any watchers at this point. 635 create/modify any watchers at this point.
580 636
581 See the EV::check watcher, below, for explanations and an example. 637 See the EV::check watcher, below, for explanations and an example.
582 638
584 watcher. 640 watcher.
585 641
586 CHECK WATCHERS - customise your event loop even more! 642 CHECK WATCHERS - customise your event loop even more!
587 $w = EV::check $callback 643 $w = EV::check $callback
588 $w = EV::check_ns $callback 644 $w = EV::check_ns $callback
645 $w = $loop->check ($callback)
646 $w = $loop->check_ns ($callback)
589 Call the callback just after the process wakes up again (after it 647 Call the callback just after the process wakes up again (after it
590 has gathered events), but before any other callbacks have been 648 has gathered events), but before any other callbacks have been
591 invoked. 649 invoked.
592 650
593 This is used to integrate other event-based software into the EV 651 This is used to integrate other event-based software into the EV
642 is done before the event loop blocks next and before "check" watchers 700 is done before the event loop blocks next and before "check" watchers
643 are being called, and only in the child after the fork. 701 are being called, and only in the child after the fork.
644 702
645 $w = EV::fork $callback 703 $w = EV::fork $callback
646 $w = EV::fork_ns $callback 704 $w = EV::fork_ns $callback
705 $w = $loop->fork ($callback)
706 $w = $loop->fork_ns ($callback)
647 Call the callback before the event loop is resumed in the child 707 Call the callback before the event loop is resumed in the child
648 process after a fork. 708 process after a fork.
649 709
650 The "fork_ns" variant doesn't start (activate) the newly created 710 The "fork_ns" variant doesn't start (activate) the newly created
651 watcher. 711 watcher.
663 to be called on every event loop iteration by installing a "EV::check" 723 to be called on every event loop iteration by installing a "EV::check"
664 watcher: 724 watcher:
665 725
666 my $async_check = EV::check sub { }; 726 my $async_check = EV::check sub { };
667 727
668 This ensures that perl shortly gets into control for a short time, and 728 This ensures that perl gets into control for a short time to handle any
669 also ensures slower overall operation. 729 pending signals, and also ensures (slightly) slower overall operation.
670 730
671THREADS 731THREADS
672 Threads are not supported by this module in any way. Perl pseudo-threads 732 Threads are not supported by this module in any way. Perl pseudo-threads
673 is evil stuff and must die. As soon as Perl gains real threads I will 733 is evil stuff and must die. As soon as Perl gains real threads I will
674 work on thread support for it. 734 work on thread support for it.
689 749
690 On win32, there is no notion of fork so all this doesn't apply, of 750 On win32, there is no notion of fork so all this doesn't apply, of
691 course. 751 course.
692 752
693SEE ALSO 753SEE ALSO
694 EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event 754 EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
695 loop), Coro::EV (efficient coroutines with EV). 755 loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
756 with EV), Net::SNMP::EV (asynchronous SNMP).
696 757
697AUTHOR 758AUTHOR
698 Marc Lehmann <schmorp@schmorp.de> 759 Marc Lehmann <schmorp@schmorp.de>
699 http://home.schmorp.de/ 760 http://home.schmorp.de/
700 761

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