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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, 1, sub {
15 warn "is called roughly every 2s (repeat = 1)";
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 get the watcher object 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 my $w = EV::signal 3, sub {
38 warn "sigquit received (this is GNU/Linux, right?)\n";
39 };
40
41 # CHILD/PID STATUS CHANGES 44 # STAT CHANGES
42 45 my $w = EV::stat "/etc/passwd", 10, sub {
43 my $w = EV::child 666, sub {
44 my ($w, $revents) = @_; 46 my ($w, $revents) = @_;
45 # my $pid = $w->rpid; 47 warn $w->path, " has changed somehow.\n";
46 my $status = $w->rstatus;
47 }; 48 };
48 49
49 # MAINLOOP 50 # MAINLOOP
50 EV::loop; # loop until EV::loop_done is called 51 EV::run; # loop until EV::break is called or all watchers stop
51 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 52 EV::run EV::RUN_ONCE; # block until at least one event could be handled
52 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 53 EV::run EV::RUN_NOWAIT; # 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.
53 63
54DESCRIPTION 64DESCRIPTION
55 This module provides an interface to libev 65 This module provides an interface to libev
56 (<http://software.schmorp.de/pkg/libev.html>). 66 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
67 below is comprehensive, one might also consult the documentation of
68 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
69 perldoc EV::libev) for more subtle details on watcher semantics or some
70 discussion on the available backends, or how to force a specific backend
71 with "LIBEV_FLAGS", or just about in any case because it has much more
72 detailed information.
73
74 This module is very fast and scalable. It is actually so fast that you
75 can use it through the AnyEvent module, stay portable to other event
76 loops (if you don't rely on any watcher types not available through it)
77 and still be faster than with any other event loop currently supported
78 in Perl.
79
80 PORTING FROM EV 3.X to 4.X
81 EV version 4 introduces a number of incompatible changes summarised
82 here. According to the depreciation strategy used by libev, there is a
83 compatibility layer in place so programs should continue to run
84 unchanged (the XS interface lacks this layer, so programs using that one
85 need to be updated).
86
87 This compatibility layer will be switched off in some future release.
88
89 All changes relevant to Perl are renames of symbols, functions and
90 methods:
91
92 EV::loop => EV::run
93 EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
94 EV::LOOP_ONESHOT => EV::RUN_ONCE
95
96 EV::unloop => EV::break
97 EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
98 EV::UNLOOP_ONE => EV::BREAK_ONE
99 EV::UNLOOP_ALL => EV::BREAK_ALL
100
101 EV::TIMEOUT => EV::TIMER
102
103 EV::loop_count => EV::iteration
104 EV::loop_depth => EV::depth
105 EV::loop_verify => EV::verify
106
107 The loop object methods corresponding to the functions above have been
108 similarly renamed.
109
110 MODULE EXPORTS
111 This module does not export any symbols.
112
113EVENT LOOPS
114 EV supports multiple event loops: There is a single "default event loop"
115 that can handle everything including signals and child watchers, and any
116 number of "dynamic event loops" that can use different backends (with
117 various limitations), but no child and signal watchers.
118
119 You do not have to do anything to create the default event loop: When
120 the module is loaded a suitable backend is selected on the premise of
121 selecting a working backend (which for example rules out kqueue on most
122 BSDs). Modules should, unless they have "special needs" always use the
123 default loop as this is fastest (perl-wise), best supported by other
124 modules (e.g. AnyEvent or Coro) and most portable event loop.
125
126 For specific programs you can create additional event loops dynamically.
127
128 If you want to take advantage of kqueue (which often works properly for
129 sockets only) even though the default loop doesn't enable it, you can
130 *embed* a kqueue loop into the default loop: running the default loop
131 will then also service the kqueue loop to some extent. See the example
132 in the section about embed watchers for an example on how to achieve
133 that.
134
135 $loop = new EV::Loop [$flags]
136 Create a new event loop as per the specified flags. Please refer to
137 the "ev_loop_new ()" function description in the libev documentation
138 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
139 ONS>, or locally-installed as EV::libev manpage) for more info.
140
141 The loop will automatically be destroyed when it is no longer
142 referenced by any watcher and the loop object goes out of scope.
143
144 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
145 is recommended, as only the default event loop is protected by this
146 module. If you *are* embedding this loop in the default loop, this
147 is not necessary, as "EV::embed" automatically does the right thing
148 on fork.
149
150 $loop->loop_fork
151 Must be called after a fork in the child, before entering or
152 continuing the event loop. An alternative is to use
153 "EV::FLAG_FORKCHECK" which calls this function automatically, at
154 some performance loss (refer to the libev documentation).
155
156 $loop->verify
157 Calls "ev_verify" to make internal consistency checks (for debugging
158 libev) and abort the program if any data structures were found to be
159 corrupted.
160
161 $loop = EV::default_loop [$flags]
162 Return the default loop (which is a singleton object). Since this
163 module already creates the default loop with default flags,
164 specifying flags here will not have any effect unless you destroy
165 the default loop first, which isn't supported. So in short: don't do
166 it, and if you break it, you get to keep the pieces.
57 167
58BASIC INTERFACE 168BASIC INTERFACE
59 $EV::DIED 169 $EV::DIED
60 Must contain a reference to a function that is called when a 170 Must contain a reference to a function that is called when a
61 callback throws an exception (with $@ containing thr error). The 171 callback throws an exception (with $@ containing the error). The
62 default prints an informative message and continues. 172 default prints an informative message and continues.
63 173
64 If this callback throws an exception it will be silently ignored. 174 If this callback throws an exception it will be silently ignored.
175
176 $flags = EV::supported_backends
177 $flags = EV::recommended_backends
178 $flags = EV::embeddable_backends
179 Returns the set (see "EV::BACKEND_*" flags) of backends supported by
180 this instance of EV, the set of recommended backends (supposed to be
181 good) for this platform and the set of embeddable backends (see
182 EMBED WATCHERS).
183
184 EV::sleep $seconds
185 Block the process for the given number of (fractional) seconds.
65 186
66 $time = EV::time 187 $time = EV::time
67 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
68 189
69 $time = EV::now 190 $time = EV::now
191 $time = $loop->now
70 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
71 This is the time that (relative) timers are based on, and refering 193 This is the time that (relative) timers are based on, and referring
72 to it is usually faster then calling EV::time. 194 to it is usually faster then calling EV::time.
73 195
74 $method = EV::ev_method 196 EV::now_update
197 $loop->now_update
198 Establishes the current time by querying the kernel, updating the
199 time returned by "EV::now" in the progress. This is a costly
200 operation and is usually done automatically within "EV::loop".
201
202 This function is rarely useful, but when some event callback runs
203 for a very long time without entering the event loop, updating
204 libev's idea of the current time is a good idea.
205
206 EV::suspend
207 $loop->suspend
208 EV::resume
209 $loop->resume
210 These two functions suspend and resume a loop, for use when the loop
211 is not used for a while and timeouts should not be processed.
212
213 A typical use case would be an interactive program such as a game:
214 When the user presses "^Z" to suspend the game and resumes it an
215 hour later it would be best to handle timeouts as if no time had
216 actually passed while the program was suspended. This can be
217 achieved by calling "suspend" in your "SIGTSTP" handler, sending
218 yourself a "SIGSTOP" and calling "resume" directly afterwards to
219 resume timer processing.
220
221 Effectively, all "timer" watchers will be delayed by the time spend
222 between "suspend" and "resume", and all "periodic" watchers will be
223 rescheduled (that is, they will lose any events that would have
224 occured while suspended).
225
226 After calling "suspend" you must not call *any* function on the
227 given loop other than "resume", and you must not call "resume"
228 without a previous call to "suspend".
229
230 Calling "suspend"/"resume" has the side effect of updating the event
231 loop time (see "now_update").
232
233 $backend = EV::backend
234 $backend = $loop->backend
75 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
76 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
77 237
78 EV::loop [$flags] 238 $active = EV::run [$flags]
239 $active = $loop->run ([$flags])
79 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
80 callback calls EV::loop_done. 241 callback calls EV::break or the flasg are nonzero (in which case the
242 return value is true) or when there are no active watchers which
243 reference the loop (keepalive is true), in which case the return
244 value will be false. The returnv alue can generally be interpreted
245 as "if true, there is more work left to do".
81 246
82 The $flags argument can be one of the following: 247 The $flags argument can be one of the following:
83 248
84 0 as above 249 0 as above
85 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 250 EV::RUN_ONCE block at most once (wait, but do not loop)
86 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 251 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
87 252
88 EV::loop_done [$how] 253 EV::break [$how]
254 $loop->break ([$how])
89 When called with no arguments or an argument of 1, makes the 255 When called with no arguments or an argument of EV::BREAK_ONE, makes
90 innermost call to EV::loop return. 256 the innermost call to EV::loop return.
91 257
92 When called with an agrument of 2, all calls to EV::loop will return 258 When called with an argument of EV::BREAK_ALL, all calls to EV::loop
93 as fast as possible. 259 will return as fast as possible.
94 260
95 WATCHER 261 When called with an argument of EV::BREAK_CANCEL, any pending break
262 will be cancelled.
263
264 $count = EV::iteration
265 $count = $loop->iteration
266 Return the number of times the event loop has polled for new events.
267 Sometimes useful as a generation counter.
268
269 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
270 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
271 This function rolls together an I/O and a timer watcher for a single
272 one-shot event without the need for managing a watcher object.
273
274 If $fh_or_undef is a filehandle or file descriptor, then $events
275 must be a bitset containing either "EV::READ", "EV::WRITE" or
276 "EV::READ | EV::WRITE", indicating the type of I/O event you want to
277 wait for. If you do not want to wait for some I/O event, specify
278 "undef" for $fh_or_undef and 0 for $events).
279
280 If timeout is "undef" or negative, then there will be no timeout.
281 Otherwise a EV::timer with this value will be started.
282
283 When an error occurs or either the timeout or I/O watcher triggers,
284 then the callback will be called with the received event set (in
285 general you can expect it to be a combination of "EV::ERROR",
286 "EV::READ", "EV::WRITE" and "EV::TIMER").
287
288 EV::once doesn't return anything: the watchers stay active till
289 either of them triggers, then they will be stopped and freed, and
290 the callback invoked.
291
292 EV::feed_fd_event $fd, $revents
293 $loop->feed_fd_event ($fd, $revents)
294 Feed an event on a file descriptor into EV. EV will react to this
295 call as if the readyness notifications specified by $revents (a
296 combination of "EV::READ" and "EV::WRITE") happened on the file
297 descriptor $fd.
298
299 EV::feed_signal_event $signal
300 Feed a signal event into the default loop. EV will react to this
301 call as if the signal specified by $signal had occured.
302
303 EV::feed_signal $signal
304 Feed a signal event into EV - unlike "EV::feed_signal_event", this
305 works regardless of which loop has registered the signal, and is
306 mainly useful fro custom signal implementations.
307
308 EV::set_io_collect_interval $time
309 $loop->set_io_collect_interval ($time)
310 EV::set_timeout_collect_interval $time
311 $loop->set_timeout_collect_interval ($time)
312 These advanced functions set the minimum block interval when polling
313 for I/O events and the minimum wait interval for timer events. See
314 the libev documentation at
315 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
316 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
317 detailed discussion.
318
319 $count = EV::pending_count
320 $count = $loop->pending_count
321 Returns the number of currently pending watchers.
322
323 EV::invoke_pending
324 $loop->invoke_pending
325 Invoke all currently pending watchers.
326
327WATCHER OBJECTS
96 A watcher is an object that gets created to record your interest in some 328 A watcher is an object that gets created to record your interest in some
97 event. For instance, if you want to wait for STDIN to become readable, 329 event. For instance, if you want to wait for STDIN to become readable,
98 you would create an EV::io watcher for that: 330 you would create an EV::io watcher for that:
99 331
100 my $watcher = EV::io *STDIN, EV::READ, sub { 332 my $watcher = EV::io *STDIN, EV::READ, sub {
101 my ($watcher, $revents) = @_; 333 my ($watcher, $revents) = @_;
102 warn "yeah, STDIN should not be readable without blocking!\n" 334 warn "yeah, STDIN should now be readable without blocking!\n"
103 }; 335 };
104 336
105 All watchers can be active (waiting for events) or inactive (paused). 337 All watchers can be active (waiting for events) or inactive (paused).
106 Only active watchers will have their callbacks invoked. All callbacks 338 Only active watchers will have their callbacks invoked. All callbacks
107 will be called with at least two arguments: the watcher and a bitmask of 339 will be called with at least two arguments: the watcher and a bitmask of
108 received events. 340 received events.
109 341
110 Each watcher type has its associated bit in revents, so you can use the 342 Each watcher type has its associated bit in revents, so you can use the
111 same callback for multiple watchers. The event mask is named after the 343 same callback for multiple watchers. The event mask is named after the
112 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 344 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
113 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 345 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
114 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 346 events (which can set both EV::READ and EV::WRITE bits).
115 (which uses EV::TIMEOUT).
116 347
117 In the rare case where one wants to create a watcher but not start it at 348 In the rare case where one wants to create a watcher but not start it at
118 the same time, each constructor has a variant with a trailing "_ns" in 349 the same time, each constructor has a variant with a trailing "_ns" in
119 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 350 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
120 351
… …
124 355
125 Also, all methods changing some aspect of a watcher (->set, ->priority, 356 Also, all methods changing some aspect of a watcher (->set, ->priority,
126 ->fh and so on) automatically stop and start it again if it is active, 357 ->fh and so on) automatically stop and start it again if it is active,
127 which means pending events get lost. 358 which means pending events get lost.
128 359
129 WATCHER TYPES 360 COMMON WATCHER METHODS
130 Now lets move to the existing watcher types and asociated methods. 361 This section lists methods common to all watchers.
131
132 The following methods are available for all watchers. Then followes a
133 description of each watcher constructor (EV::io, EV::timer,
134 EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and
135 EV::check), followed by any type-specific methods (if any).
136 362
137 $w->start 363 $w->start
138 Starts a watcher if it isn't active already. Does nothing to an 364 Starts a watcher if it isn't active already. Does nothing to an
139 already active watcher. By default, all watchers start out in the 365 already active watcher. By default, all watchers start out in the
140 active state (see the description of the "_ns" variants if you need 366 active state (see the description of the "_ns" variants if you need
141 stopped watchers). 367 stopped watchers).
142 368
143 $w->stop 369 $w->stop
144 Stop a watcher if it is active. Also clear any pending events 370 Stop a watcher if it is active. Also clear any pending events
145 (events that have been received but that didn't yet result in a 371 (events that have been received but that didn't yet result in a
146 callback invocation), regardless of wether the watcher was active or 372 callback invocation), regardless of whether the watcher was active
147 not. 373 or not.
148 374
149 $bool = $w->is_active 375 $bool = $w->is_active
150 Returns true if the watcher is active, false otherwise. 376 Returns true if the watcher is active, false otherwise.
151 377
152 $current_data = $w->data 378 $current_data = $w->data
… …
170 Pending watchers with higher priority will be invoked first. The 396 Pending watchers with higher priority will be invoked first. The
171 valid range of priorities lies between EV::MAXPRI (default 2) and 397 valid range of priorities lies between EV::MAXPRI (default 2) and
172 EV::MINPRI (default -2). If the priority is outside this range it 398 EV::MINPRI (default -2). If the priority is outside this range it
173 will automatically be normalised to the nearest valid priority. 399 will automatically be normalised to the nearest valid priority.
174 400
175 The default priority of any newly-created weatcher is 0. 401 The default priority of any newly-created watcher is 0.
176 402
403 Note that the priority semantics have not yet been fleshed out and
404 are subject to almost certain change.
405
177 $w->trigger ($revents) 406 $w->invoke ($revents)
178 Call the callback *now* with the given event mask. 407 Call the callback *now* with the given event mask.
179 408
409 $w->feed_event ($revents)
410 Feed some events on this watcher into EV. EV will react to this call
411 as if the watcher had received the given $revents mask.
412
413 $revents = $w->clear_pending
414 If the watcher is pending, this function clears its pending status
415 and returns its $revents bitset (as if its callback was invoked). If
416 the watcher isn't pending it does nothing and returns 0.
417
418 $previous_state = $w->keepalive ($bool)
419 Normally, "EV::loop" will return when there are no active watchers
420 (which is a "deadlock" because no progress can be made anymore).
421 This is convenient because it allows you to start your watchers (and
422 your jobs), call "EV::loop" once and when it returns you know that
423 all your jobs are finished (or they forgot to register some watchers
424 for their task :).
425
426 Sometimes, however, this gets in your way, for example when the
427 module that calls "EV::loop" (usually the main program) is not the
428 same module as a long-living watcher (for example a DNS client
429 module written by somebody else even). Then you might want any
430 outstanding requests to be handled, but you would not want to keep
431 "EV::loop" from returning just because you happen to have this
432 long-running UDP port watcher.
433
434 In this case you can clear the keepalive status, which means that
435 even though your watcher is active, it won't keep "EV::loop" from
436 returning.
437
438 The initial value for keepalive is true (enabled), and you can
439 change it any time.
440
441 Example: Register an I/O watcher for some UDP socket but do not keep
442 the event loop from running just because of that watcher.
443
444 my $udp_socket = ...
445 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
446 $udp_watcher->keepalive (0);
447
448 $loop = $w->loop
449 Return the loop that this watcher is attached to.
450
451WATCHER TYPES
452 Each of the following subsections describes a single watcher type.
453
454 I/O WATCHERS - is this file descriptor readable or writable?
180 $w = EV::io $fileno_or_fh, $eventmask, $callback 455 $w = EV::io $fileno_or_fh, $eventmask, $callback
181 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 456 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
457 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
458 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
182 As long as the returned watcher object is alive, call the $callback 459 As long as the returned watcher object is alive, call the $callback
183 when the events specified in $eventmask. 460 when at least one of events specified in $eventmask occurs.
184 461
185 The $eventmask can be one or more of these constants ORed together: 462 The $eventmask can be one or more of these constants ORed together:
186 463
187 EV::READ wait until read() wouldn't block anymore 464 EV::READ wait until read() wouldn't block anymore
188 EV::WRITE wait until write() wouldn't block anymore 465 EV::WRITE wait until write() wouldn't block anymore
… …
200 477
201 $current_eventmask = $w->events 478 $current_eventmask = $w->events
202 $old_eventmask = $w->events ($new_eventmask) 479 $old_eventmask = $w->events ($new_eventmask)
203 Returns the previously set event mask and optionally set a new one. 480 Returns the previously set event mask and optionally set a new one.
204 481
482 TIMER WATCHERS - relative and optionally repeating timeouts
205 $w = EV::timer $after, $repeat, $callback 483 $w = EV::timer $after, $repeat, $callback
206 $w = EV::timer_ns $after, $repeat, $callback 484 $w = EV::timer_ns $after, $repeat, $callback
207 Calls the callback after $after seconds. If $repeat is non-zero, the 485 $w = $loop->timer ($after, $repeat, $callback)
208 timer will be restarted (with the $repeat value as $after) after the 486 $w = $loop->timer_ns ($after, $repeat, $callback)
209 callback returns. 487 Calls the callback after $after seconds (which may be fractional).
488 If $repeat is non-zero, the timer will be restarted (with the
489 $repeat value as $after) after the callback returns.
210 490
211 This means that the callback would be called roughly after $after 491 This means that the callback would be called roughly after $after
212 seconds, and then every $repeat seconds. "Roughly" because the time 492 seconds, and then every $repeat seconds. The timer does his best not
213 of callback processing is not taken into account, so the timer will 493 to drift, but it will not invoke the timer more often then once per
214 slowly drift. If that isn't acceptable, look at EV::periodic. 494 event loop iteration, and might drift in other cases. If that isn't
495 acceptable, look at EV::periodic, which can provide long-term stable
496 timers.
215 497
216 The timer is based on a monotonic clock, that is if somebody is 498 The timer is based on a monotonic clock, that is, if somebody is
217 sitting in front of the machine while the timer is running and 499 sitting in front of the machine while the timer is running and
218 changes the system clock, the timer will nevertheless run (roughly) 500 changes the system clock, the timer will nevertheless run (roughly)
219 the same time. 501 the same time.
220 502
221 The "timer_ns" variant doesn't start (activate) the newly created 503 The "timer_ns" variant doesn't start (activate) the newly created
222 watcher. 504 watcher.
223 505
224 $w->set ($after, $repeat) 506 $w->set ($after, $repeat = 0)
225 Reconfigures the watcher, see the constructor above for details. Can 507 Reconfigures the watcher, see the constructor above for details. Can
226 be at any time. 508 be called at any time.
227 509
228 $w->again 510 $w->again
511 $w->again ($repeat)
229 Similar to the "start" method, but has special semantics for 512 Similar to the "start" method, but has special semantics for
230 repeating timers: 513 repeating timers:
231 514
515 If the timer is active and non-repeating, it will be stopped.
516
232 If the timer is active and repeating, reset the timeout to occur 517 If the timer is active and repeating, reset the timeout to occur
233 $repeat seconds after now. 518 $repeat seconds after now.
234 519
235 If the timer is active and non-repeating, it will be stopped.
236
237 If the timer is in active and repeating, start it. 520 If the timer is inactive and repeating, start it using the repeat
521 value.
238 522
239 Otherwise do nothing. 523 Otherwise do nothing.
240 524
241 This behaviour is useful when you have a timeout for some IO 525 This behaviour is useful when you have a timeout for some IO
242 operation. You create a timer object with the same value for $after 526 operation. You create a timer object with the same value for $after
243 and $repeat, and then, in the read/write watcher, run the "again" 527 and $repeat, and then, in the read/write watcher, run the "again"
244 method on the timeout. 528 method on the timeout.
245 529
530 If called with a $repeat argument, then it uses this a timer repeat
531 value.
532
533 $after = $w->remaining
534 Calculates and returns the remaining time till the timer will fire.
535
536 PERIODIC WATCHERS - to cron or not to cron?
246 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 537 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
247 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 538 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
539 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
540 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
248 Similar to EV::timer, but is not based on relative timeouts but on 541 Similar to EV::timer, but is not based on relative timeouts but on
249 absolute times. Apart from creating "simple" timers that trigger 542 absolute times. Apart from creating "simple" timers that trigger
250 "at" the specified time, it can also be used for non-drifting 543 "at" the specified time, it can also be used for non-drifting
251 absolute timers and more complex, cron-like, setups that are not 544 absolute timers and more complex, cron-like, setups that are not
252 adversely affected by time jumps (i.e. when the system clock is 545 adversely affected by time jumps (i.e. when the system clock is
253 changed by explicit date -s or other means such as ntpd). It is also 546 changed by explicit date -s or other means such as ntpd). It is also
254 the most complex watcher type in EV. 547 the most complex watcher type in EV.
255 548
256 It has three distinct "modes": 549 It has three distinct "modes":
257 550
258 * absolute timer ($interval = $reschedule_cb = 0) 551 * absolute timer ($interval = $reschedule_cb = 0)
552
259 This time simply fires at the wallclock time $at and doesn't 553 This time simply fires at the wallclock time $at and doesn't
260 repeat. It will not adjust when a time jump occurs, that is, if 554 repeat. It will not adjust when a time jump occurs, that is, if
261 it is to be run at January 1st 2011 then it will run when the 555 it is to be run at January 1st 2011 then it will run when the
262 system time reaches or surpasses this time. 556 system time reaches or surpasses this time.
263 557
264 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 558 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
559
265 In this mode the watcher will always be scheduled to time out at 560 In this mode the watcher will always be scheduled to time out at
266 the next "$at + N * $interval" time (for some integer N) and 561 the next "$at + N * $interval" time (for some integer N) and
267 then repeat, regardless of any time jumps. 562 then repeat, regardless of any time jumps.
268 563
269 This can be used to create timers that do not drift with respect 564 This can be used to create timers that do not drift with respect
270 to system time: 565 to system time:
271 566
272 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; 567 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
273 568
274 That doesn't mean there will always be 3600 seconds in between 569 That doesn't mean there will always be 3600 seconds in between
275 triggers, but only that the the clalback will be called when the 570 triggers, but only that the the callback will be called when the
276 system time shows a full hour (UTC). 571 system time shows a full hour (UTC).
277 572
278 Another way to think about it (for the mathematically inclined) 573 Another way to think about it (for the mathematically inclined)
279 is that EV::periodic will try to run the callback in this mode 574 is that EV::periodic will try to run the callback in this mode
280 at the next possible time where "$time = $at (mod $interval)", 575 at the next possible time where "$time = $at (mod $interval)",
281 regardless of any time jumps. 576 regardless of any time jumps.
282 577
283 * manual reschedule mode ($reschedule_cb = coderef) 578 * manual reschedule mode ($reschedule_cb = coderef)
579
284 In this mode $interval and $at are both being ignored. Instead, 580 In this mode $interval and $at are both being ignored. Instead,
285 each time the periodic watcher gets scheduled, the first 581 each time the periodic watcher gets scheduled, the reschedule
286 callback ($reschedule_cb) will be called with the watcher as 582 callback ($reschedule_cb) will be called with the watcher as
287 first, and the current time as second argument. 583 first, and the current time as second argument.
288 584
289 *This callback MUST NOT stop or destroy this or any other 585 *This callback MUST NOT stop or destroy this or any other
586 periodic watcher, ever, and MUST NOT call any event loop
290 periodic watcher, ever*. If you need to stop it, return 1e30 and 587 functions or methods*. If you need to stop it, return 1e30 and
291 stop it afterwards. 588 stop it afterwards. You may create and start a "EV::prepare"
589 watcher for this task.
292 590
293 It must return the next time to trigger, based on the passed 591 It must return the next time to trigger, based on the passed
294 time value (that is, the lowest time value larger than to the 592 time value (that is, the lowest time value larger than or equal
295 second argument). It will usually be called just before the 593 to to the second argument). It will usually be called just
296 callback will be triggered, but might be called at other times, 594 before the callback will be triggered, but might be called at
297 too. 595 other times, too.
298 596
299 This can be used to create very complex timers, such as a timer 597 This can be used to create very complex timers, such as a timer
300 that triggers on each midnight, local time (actually 24 hours 598 that triggers on each midnight, local time (actually 24 hours
301 after the last midnight, to keep the example simple. If you know 599 after the last midnight, to keep the example simple. If you know
302 a way to do it correctly in about the same space (without 600 a way to do it correctly in about the same space (without
… …
315 The "periodic_ns" variant doesn't start (activate) the newly created 613 The "periodic_ns" variant doesn't start (activate) the newly created
316 watcher. 614 watcher.
317 615
318 $w->set ($at, $interval, $reschedule_cb) 616 $w->set ($at, $interval, $reschedule_cb)
319 Reconfigures the watcher, see the constructor above for details. Can 617 Reconfigures the watcher, see the constructor above for details. Can
320 be at any time. 618 be called at any time.
321 619
322 $w->again 620 $w->again
323 Simply stops and starts the watcher again. 621 Simply stops and starts the watcher again.
324 622
623 $time = $w->at
624 Return the time that the watcher is expected to trigger next.
625
626 SIGNAL WATCHERS - signal me when a signal gets signalled!
325 $w = EV::signal $signal, $callback 627 $w = EV::signal $signal, $callback
326 $w = EV::signal_ns $signal, $callback 628 $w = EV::signal_ns $signal, $callback
629 $w = $loop->signal ($signal, $callback)
630 $w = $loop->signal_ns ($signal, $callback)
327 Call the callback when $signal is received (the signal can be 631 Call the callback when $signal is received (the signal can be
328 specified by number or by name, just as with kill or %SIG). 632 specified by number or by name, just as with "kill" or %SIG).
633
634 Only one event loop can grab a given signal - attempting to grab the
635 same signal from two EV loops will crash the program immediately or
636 cause data corruption.
329 637
330 EV will grab the signal for the process (the kernel only allows one 638 EV will grab the signal for the process (the kernel only allows one
331 component to receive a signal at a time) when you start a signal 639 component to receive a signal at a time) when you start a signal
332 watcher, and removes it again when you stop it. Perl does the same 640 watcher, and removes it again when you stop it. Perl does the same
333 when you add/remove callbacks to %SIG, so watch out. 641 when you add/remove callbacks to %SIG, so watch out.
… …
337 The "signal_ns" variant doesn't start (activate) the newly created 645 The "signal_ns" variant doesn't start (activate) the newly created
338 watcher. 646 watcher.
339 647
340 $w->set ($signal) 648 $w->set ($signal)
341 Reconfigures the watcher, see the constructor above for details. Can 649 Reconfigures the watcher, see the constructor above for details. Can
342 be at any time. 650 be called at any time.
343 651
344 $current_signum = $w->signal 652 $current_signum = $w->signal
345 $old_signum = $w->signal ($new_signal) 653 $old_signum = $w->signal ($new_signal)
346 Returns the previously set signal (always as a number not name) and 654 Returns the previously set signal (always as a number not name) and
347 optionally set a new one. 655 optionally set a new one.
348 656
657 CHILD WATCHERS - watch out for process status changes
349 $w = EV::child $pid, $callback 658 $w = EV::child $pid, $trace, $callback
350 $w = EV::child_ns $pid, $callback 659 $w = EV::child_ns $pid, $trace, $callback
660 $w = $loop->child ($pid, $trace, $callback)
661 $w = $loop->child_ns ($pid, $trace, $callback)
351 Call the callback when a status change for pid $pid (or any pid if 662 Call the callback when a status change for pid $pid (or any pid if
352 $pid is 0) has been received. More precisely: when the process 663 $pid is 0) has been received (a status change happens when the
664 process terminates or is killed, or, when trace is true,
665 additionally when it is stopped or continued). More precisely: when
353 receives a SIGCHLD, EV will fetch the outstanding exit/wait status 666 the process receives a "SIGCHLD", EV will fetch the outstanding
354 for all changed/zombie children and call the callback. 667 exit/wait status for all changed/zombie children and call the
668 callback.
355 669
356 You can access both status and pid by using the "rstatus" and "rpid" 670 It is valid (and fully supported) to install a child watcher after a
671 child has exited but before the event loop has started its next
672 iteration (for example, first you "fork", then the new child process
673 might exit, and only then do you install a child watcher in the
674 parent for the new pid).
675
676 You can access both exit (or tracing) status and pid by using the
357 methods on the watcher object. 677 "rstatus" and "rpid" methods on the watcher object.
358 678
359 You can have as many pid watchers per pid as you want. 679 You can have as many pid watchers per pid as you want, they will all
680 be called.
360 681
361 The "child_ns" variant doesn't start (activate) the newly created 682 The "child_ns" variant doesn't start (activate) the newly created
362 watcher. 683 watcher.
363 684
364 $w->set ($pid) 685 $w->set ($pid, $trace)
365 Reconfigures the watcher, see the constructor above for details. Can 686 Reconfigures the watcher, see the constructor above for details. Can
366 be at any time. 687 be called at any time.
367 688
368 $current_pid = $w->pid 689 $current_pid = $w->pid
369 $old_pid = $w->pid ($new_pid)
370 Returns the previously set process id and optionally set a new one. 690 Returns the previously set process id and optionally set a new one.
371 691
372 $exit_status = $w->rstatus 692 $exit_status = $w->rstatus
373 Return the exit/wait status (as returned by waitpid, see the waitpid 693 Return the exit/wait status (as returned by waitpid, see the waitpid
374 entry in perlfunc). 694 entry in perlfunc).
375 695
376 $pid = $w->rpid 696 $pid = $w->rpid
377 Return the pid of the awaited child (useful when you have installed 697 Return the pid of the awaited child (useful when you have installed
378 a watcher for all pids). 698 a watcher for all pids).
379 699
700 STAT WATCHERS - did the file attributes just change?
701 $w = EV::stat $path, $interval, $callback
702 $w = EV::stat_ns $path, $interval, $callback
703 $w = $loop->stat ($path, $interval, $callback)
704 $w = $loop->stat_ns ($path, $interval, $callback)
705 Call the callback when a file status change has been detected on
706 $path. The $path does not need to exist, changing from "path exists"
707 to "path does not exist" is a status change like any other.
708
709 The $interval is a recommended polling interval for systems where
710 OS-supported change notifications don't exist or are not supported.
711 If you use 0 then an unspecified default is used (which is highly
712 recommended!), which is to be expected to be around five seconds
713 usually.
714
715 This watcher type is not meant for massive numbers of stat watchers,
716 as even with OS-supported change notifications, this can be
717 resource-intensive.
718
719 The "stat_ns" variant doesn't start (activate) the newly created
720 watcher.
721
722 ... = $w->stat
723 This call is very similar to the perl "stat" built-in: It stats
724 (using "lstat") the path specified in the watcher and sets perls
725 stat cache (as well as EV's idea of the current stat values) to the
726 values found.
727
728 In scalar context, a boolean is return indicating success or failure
729 of the stat. In list context, the same 13-value list as with stat is
730 returned (except that the blksize and blocks fields are not
731 reliable).
732
733 In the case of an error, errno is set to "ENOENT" (regardless of the
734 actual error value) and the "nlink" value is forced to zero (if the
735 stat was successful then nlink is guaranteed to be non-zero).
736
737 See also the next two entries for more info.
738
739 ... = $w->attr
740 Just like "$w->stat", but without the initial stat'ing: this returns
741 the values most recently detected by EV. See the next entry for more
742 info.
743
744 ... = $w->prev
745 Just like "$w->stat", but without the initial stat'ing: this returns
746 the previous set of values, before the change.
747
748 That is, when the watcher callback is invoked, "$w->prev" will be
749 set to the values found *before* a change was detected, while
750 "$w->attr" returns the values found leading to the change detection.
751 The difference (if any) between "prev" and "attr" is what triggered
752 the callback.
753
754 If you did something to the filesystem object and do not want to
755 trigger yet another change, you can call "stat" to update EV's idea
756 of what the current attributes are.
757
758 $w->set ($path, $interval)
759 Reconfigures the watcher, see the constructor above for details. Can
760 be called at any time.
761
762 $current_path = $w->path
763 $old_path = $w->path ($new_path)
764 Returns the previously set path and optionally set a new one.
765
766 $current_interval = $w->interval
767 $old_interval = $w->interval ($new_interval)
768 Returns the previously set interval and optionally set a new one.
769 Can be used to query the actual interval used.
770
771 IDLE WATCHERS - when you've got nothing better to do...
380 $w = EV::idle $callback 772 $w = EV::idle $callback
381 $w = EV::idle_ns $callback 773 $w = EV::idle_ns $callback
774 $w = $loop->idle ($callback)
775 $w = $loop->idle_ns ($callback)
382 Call the callback when there are no pending io, timer/periodic, 776 Call the callback when there are no other pending watchers of the
383 signal or child events, i.e. when the process is idle. 777 same or higher priority (excluding check, prepare and other idle
778 watchers of the same or lower priority, of course). They are called
779 idle watchers because when the watcher is the highest priority
780 pending event in the process, the process is considered to be idle
781 at that priority.
782
783 If you want a watcher that is only ever called when *no* other
784 events are outstanding you have to set the priority to "EV::MINPRI".
384 785
385 The process will not block as long as any idle watchers are active, 786 The process will not block as long as any idle watchers are active,
386 and they will be called repeatedly until stopped. 787 and they will be called repeatedly until stopped.
387 788
789 For example, if you have idle watchers at priority 0 and 1, and an
790 I/O watcher at priority 0, then the idle watcher at priority 1 and
791 the I/O watcher will always run when ready. Only when the idle
792 watcher at priority 1 is stopped and the I/O watcher at priority 0
793 is not pending with the 0-priority idle watcher be invoked.
794
388 The "idle_ns" variant doesn't start (activate) the newly created 795 The "idle_ns" variant doesn't start (activate) the newly created
389 watcher. 796 watcher.
390 797
798 PREPARE WATCHERS - customise your event loop!
391 $w = EV::prepare $callback 799 $w = EV::prepare $callback
392 $w = EV::prepare_ns $callback 800 $w = EV::prepare_ns $callback
801 $w = $loop->prepare ($callback)
802 $w = $loop->prepare_ns ($callback)
393 Call the callback just before the process would block. You can still 803 Call the callback just before the process would block. You can still
394 create/modify any watchers at this point. 804 create/modify any watchers at this point.
395 805
396 See the EV::check watcher, below, for explanations and an example. 806 See the EV::check watcher, below, for explanations and an example.
397 807
398 The "prepare_ns" variant doesn't start (activate) the newly created 808 The "prepare_ns" variant doesn't start (activate) the newly created
399 watcher. 809 watcher.
400 810
811 CHECK WATCHERS - customise your event loop even more!
401 $w = EV::check $callback 812 $w = EV::check $callback
402 $w = EV::check_ns $callback 813 $w = EV::check_ns $callback
814 $w = $loop->check ($callback)
815 $w = $loop->check_ns ($callback)
403 Call the callback just after the process wakes up again (after it 816 Call the callback just after the process wakes up again (after it
404 has gathered events), but before any other callbacks have been 817 has gathered events), but before any other callbacks have been
405 invoked. 818 invoked.
406 819
407 This is used to integrate other event-based software into the EV 820 This can be used to integrate other event-based software into the EV
408 mainloop: You register a prepare callback and in there, you create 821 mainloop: You register a prepare callback and in there, you create
409 io and timer watchers as required by the other software. Here is a 822 io and timer watchers as required by the other software. Here is a
410 real-world example of integrating Net::SNMP (with some details left 823 real-world example of integrating Net::SNMP (with some details left
411 out): 824 out):
412 825
… …
416 # do nothing unless active 829 # do nothing unless active
417 $dispatcher->{_event_queue_h} 830 $dispatcher->{_event_queue_h}
418 or return; 831 or return;
419 832
420 # make the dispatcher handle any outstanding stuff 833 # make the dispatcher handle any outstanding stuff
834 ... not shown
421 835
422 # create an IO watcher for each and every socket 836 # create an I/O watcher for each and every socket
423 @snmp_watcher = ( 837 @snmp_watcher = (
424 (map { EV::io $_, EV::READ, sub { } } 838 (map { EV::io $_, EV::READ, sub { } }
425 keys %{ $dispatcher->{_descriptors} }), 839 keys %{ $dispatcher->{_descriptors} }),
840
841 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
842 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
843 0, sub { },
426 ); 844 );
427
428 # if there are any timeouts, also create a timer
429 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
430 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
431 }; 845 };
432 846
433 The callbacks are irrelevant, the only purpose of those watchers is 847 The callbacks are irrelevant (and are not even being called), the
434 to wake up the process as soon as one of those events occurs (socket 848 only purpose of those watchers is to wake up the process as soon as
435 readable, or timer timed out). The corresponding EV::check watcher 849 one of those events occurs (socket readable, or timer timed out).
436 will then clean up: 850 The corresponding EV::check watcher will then clean up:
437 851
438 our $snmp_check = EV::check sub { 852 our $snmp_check = EV::check sub {
439 # destroy all watchers 853 # destroy all watchers
440 @snmp_watcher = (); 854 @snmp_watcher = ();
441 855
442 # make the dispatcher handle any new stuff 856 # make the dispatcher handle any new stuff
857 ... not shown
443 }; 858 };
444 859
445 The callbacks of the created watchers will not be called as the 860 The callbacks of the created watchers will not be called as the
446 watchers are destroyed before this cna happen (remember EV::check 861 watchers are destroyed before this can happen (remember EV::check
447 gets called first). 862 gets called first).
448 863
449 The "check_ns" variant doesn't start (activate) the newly created 864 The "check_ns" variant doesn't start (activate) the newly created
450 watcher. 865 watcher.
451 866
867 EV::CHECK constant issues
868 Like all other watcher types, there is a bitmask constant for use in
869 $revents and other places. The "EV::CHECK" is special as it has the
870 same name as the "CHECK" sub called by Perl. This doesn't cause big
871 issues on newer perls (beginning with 5.8.9), but it means thatthe
872 constant must be *inlined*, i.e. runtime calls will not work. That
873 means that as long as you always "use EV" and then "EV::CHECK" you
874 are on the safe side.
875
876 FORK WATCHERS - the audacity to resume the event loop after a fork
877 Fork watchers are called when a "fork ()" was detected. The invocation
878 is done before the event loop blocks next and before "check" watchers
879 are being called, and only in the child after the fork.
880
881 $w = EV::fork $callback
882 $w = EV::fork_ns $callback
883 $w = $loop->fork ($callback)
884 $w = $loop->fork_ns ($callback)
885 Call the callback before the event loop is resumed in the child
886 process after a fork.
887
888 The "fork_ns" variant doesn't start (activate) the newly created
889 watcher.
890
891 EMBED WATCHERS - when one backend isn't enough...
892 This is a rather advanced watcher type that lets you embed one event
893 loop into another (currently only IO events are supported in the
894 embedded loop, other types of watchers might be handled in a delayed or
895 incorrect fashion and must not be used).
896
897 See the libev documentation at
898 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
899 _when_one_backend_> (locally installed as EV::libev) for more details.
900
901 In short, this watcher is most useful on BSD systems without working
902 kqueue to still be able to handle a large number of sockets:
903
904 my $socket_loop;
905
906 # check wether we use SELECT or POLL _and_ KQUEUE is supported
907 if (
908 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
909 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
910 ) {
911 # use kqueue for sockets
912 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
913 }
914
915 # use the default loop otherwise
916 $socket_loop ||= EV::default_loop;
917
918 $w = EV::embed $otherloop[, $callback]
919 $w = EV::embed_ns $otherloop[, $callback]
920 $w = $loop->embed ($otherloop[, $callback])
921 $w = $loop->embed_ns ($otherloop[, $callback])
922 Call the callback when the embedded event loop ($otherloop) has any
923 I/O activity. The $callback is optional: if it is missing, then the
924 embedded event loop will be managed automatically (which is
925 recommended), otherwise you have to invoke "sweep" yourself.
926
927 The "embed_ns" variant doesn't start (activate) the newly created
928 watcher.
929
930 ASYNC WATCHERS - how to wake up another event loop
931 Async watchers are provided by EV, but have little use in perl directly,
932 as perl neither supports threads running in parallel nor direct access
933 to signal handlers or other contexts where they could be of value.
934
935 It is, however, possible to use them from the XS level.
936
937 Please see the libev documentation for further details.
938
939 $w = EV::async $callback
940 $w = EV::async_ns $callback
941 $w = $loop->async ($callback)
942 $w = $loop->async_ns ($callback)
943 $w->send
944 $bool = $w->async_pending
945
946 CLEANUP WATCHERS - how to clean up when the event loop goes away
947 Cleanup watchers are not supported on the Perl level, they can only be
948 used via XS currently.
949
950PERL SIGNALS
951 While Perl signal handling (%SIG) is not affected by EV, the behaviour
952 with EV is as the same as any other C library: Perl-signals will only be
953 handled when Perl runs, which means your signal handler might be invoked
954 only the next time an event callback is invoked.
955
956 The solution is to use EV signal watchers (see "EV::signal"), which will
957 ensure proper operations with regards to other event watchers.
958
959 If you cannot do this for whatever reason, you can also force a watcher
960 to be called on every event loop iteration by installing a "EV::check"
961 watcher:
962
963 my $async_check = EV::check sub { };
964
965 This ensures that perl gets into control for a short time to handle any
966 pending signals, and also ensures (slightly) slower overall operation.
967
452THREADS 968ITHREADS
453 Threads are not supported by this in any way. Perl pseudo-threads is 969 Ithreads are not supported by this module in any way. Perl
454 evil stuff and must die. 970 pseudo-threads is evil stuff and must die. Real threads as provided by
971 Coro are fully supported (and enhanced support is available via
972 Coro::EV).
973
974FORK
975 Most of the "improved" event delivering mechanisms of modern operating
976 systems have quite a few problems with fork(2) (to put it bluntly: it is
977 not supported and usually destructive). Libev makes it possible to work
978 around this by having a function that recreates the kernel state after
979 fork in the child.
980
981 On non-win32 platforms, this module requires the pthread_atfork
982 functionality to do this automatically for you. This function is quite
983 buggy on most BSDs, though, so YMMV. The overhead for this is quite
984 negligible, because everything the function currently does is set a flag
985 that is checked only when the event loop gets used the next time, so
986 when you do fork but not use EV, the overhead is minimal.
987
988 On win32, there is no notion of fork so all this doesn't apply, of
989 course.
455 990
456SEE ALSO 991SEE ALSO
457 L<EV::DNS>, L<EV::AnyEvent>. 992 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
993 DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed
994 Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV
995 (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event
996 driven programming.
458 997
459AUTHOR 998AUTHOR
460 Marc Lehmann <schmorp@schmorp.de> 999 Marc Lehmann <schmorp@schmorp.de>
461 http://home.schmorp.de/ 1000 http://home.schmorp.de/
462 1001

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