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1NAME 1NAME
2 EV - perl interface to libev, a high performance full-featured event 2 EV - perl interface to libev, a high performance full-featured event
3 loop 3 loop
4 4
5SYNOPSIS 5SYNOPSIS
6 use EV; 6 use EV;
7
8 # TIMERS
9
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
7 38
8 # TIMERS 39 my $w = EV::child 666, 0, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
9 43
10 my $w = EV::timer 2, 0, sub {
11 warn "is called after 2s";
12 };
13
14 my $w = EV::timer 2, 2, sub {
15 warn "is called roughly every 2s (repeat = 2)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, 0, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 # CHILD/PID STATUS CHANGES
38
39 my $w = EV::child 666, sub {
40 my ($w, $revents) = @_;
41 my $status = $w->rstatus;
42 };
43
44 # STAT CHANGES 44 # STAT CHANGES
45 my $w = EV::stat "/etc/passwd", 10, sub { 45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_; 46 my ($w, $revents) = @_;
47 warn $w->path, " has changed somehow.\n"; 47 warn $w->path, " has changed somehow.\n";
48 }; 48 };
49 49
50 # MAINLOOP 50 # MAINLOOP
51 EV::loop; # loop until EV::unloop is called or all watchers stop 51 EV::run; # loop until EV::break is called or all watchers stop
52 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
53 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.
54 63
55DESCRIPTION 64DESCRIPTION
56 This module provides an interface to libev 65 This module provides an interface to libev
57 (<http://software.schmorp.de/pkg/libev.html>). While the documentation 66 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
58 below is comprehensive, one might also consult the documentation of 67 below is comprehensive, one might also consult the documentation of
59 libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle 68 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
60 details on watcher semantics or some discussion on the available 69 perldoc EV::libev) for more subtle details on watcher semantics or some
61 backends, or how to force a specific backend with "LIBEV_FLAGS". 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.
62 167
63BASIC INTERFACE 168BASIC INTERFACE
64 $EV::DIED 169 $EV::DIED
65 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
66 callback throws an exception (with $@ containing thr error). The 171 callback throws an exception (with $@ containing the error). The
67 default prints an informative message and continues. 172 default prints an informative message and continues.
68 173
69 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.
70 186
71 $time = EV::time 187 $time = EV::time
72 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
73 189
74 $time = EV::now 190 $time = EV::now
191 $time = $loop->now
75 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
76 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
77 to it is usually faster then calling EV::time. 194 to it is usually faster then calling EV::time.
78 195
79 $method = 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 = $loop->backend
80 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
81 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
82 237
83 EV::loop [$flags] 238 $active = EV::run [$flags]
239 $active = $loop->run ([$flags])
84 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
85 callback calls EV::unloop. 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".
86 246
87 The $flags argument can be one of the following: 247 The $flags argument can be one of the following:
88 248
89 0 as above 249 0 as above
90 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 250 EV::RUN_ONCE block at most once (wait, but do not loop)
91 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 251 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
92 252
93 EV::unloop [$how] 253 EV::break [$how]
254 $loop->break ([$how])
94 When called with no arguments or an argument of EV::UNLOOP_ONE, 255 When called with no arguments or an argument of EV::BREAK_ONE, makes
95 makes the innermost call to EV::loop return. 256 the innermost call to EV::loop return.
96 257
97 When called with an argument of EV::UNLOOP_ALL, all calls to 258 When called with an argument of EV::BREAK_ALL, all calls to EV::loop
98 EV::loop will return as fast as possible. 259 will return as fast as possible.
99 260
100 $count = EV::loop_count 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
101 Return the number of times the event loop has polled for new events. 266 Return the number of times the event loop has polled for new events.
102 Sometiems useful as a generation counter. 267 Sometimes useful as a generation counter.
103 268
104 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 269 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
270 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
105 This function rolls together an I/O and a timer watcher for a single 271 This function rolls together an I/O and a timer watcher for a single
106 one-shot event without the need for managing a watcher object. 272 one-shot event without the need for managing a watcher object.
107 273
108 If $fh_or_undef is a filehandle or file descriptor, then $events 274 If $fh_or_undef is a filehandle or file descriptor, then $events
109 must be a bitset containing either "EV::READ", "EV::WRITE" or 275 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
114 If timeout is "undef" or negative, then there will be no timeout. 280 If timeout is "undef" or negative, then there will be no timeout.
115 Otherwise a EV::timer with this value will be started. 281 Otherwise a EV::timer with this value will be started.
116 282
117 When an error occurs or either the timeout or I/O watcher triggers, 283 When an error occurs or either the timeout or I/O watcher triggers,
118 then the callback will be called with the received event set (in 284 then the callback will be called with the received event set (in
119 general you can expect it to be a combination of "EV:ERROR", 285 general you can expect it to be a combination of "EV::ERROR",
120 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 286 "EV::READ", "EV::WRITE" and "EV::TIMER").
121 287
122 EV::once doesn't return anything: the watchers stay active till 288 EV::once doesn't return anything: the watchers stay active till
123 either of them triggers, then they will be stopped and freed, and 289 either of them triggers, then they will be stopped and freed, and
124 the callback invoked. 290 the callback invoked.
125 291
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
126 WATCHER OBJECTS 327WATCHER OBJECTS
127 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
128 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,
129 you would create an EV::io watcher for that: 330 you would create an EV::io watcher for that:
130 331
131 my $watcher = EV::io *STDIN, EV::READ, sub { 332 my $watcher = EV::io *STDIN, EV::READ, sub {
132 my ($watcher, $revents) = @_; 333 my ($watcher, $revents) = @_;
133 warn "yeah, STDIN should not be readable without blocking!\n" 334 warn "yeah, STDIN should now be readable without blocking!\n"
134 }; 335 };
135 336
136 All watchers can be active (waiting for events) or inactive (paused). 337 All watchers can be active (waiting for events) or inactive (paused).
137 Only active watchers will have their callbacks invoked. All callbacks 338 Only active watchers will have their callbacks invoked. All callbacks
138 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
139 received events. 340 received events.
140 341
141 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
142 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
143 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,
144 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
145 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).
146 (which uses EV::TIMEOUT).
147 347
148 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
149 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
150 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.
151 351
… …
167 stopped watchers). 367 stopped watchers).
168 368
169 $w->stop 369 $w->stop
170 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
171 (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
172 callback invocation), regardless of wether the watcher was active or 372 callback invocation), regardless of whether the watcher was active
173 not. 373 or not.
174 374
175 $bool = $w->is_active 375 $bool = $w->is_active
176 Returns true if the watcher is active, false otherwise. 376 Returns true if the watcher is active, false otherwise.
177 377
178 $current_data = $w->data 378 $current_data = $w->data
… …
201 The default priority of any newly-created watcher is 0. 401 The default priority of any newly-created watcher is 0.
202 402
203 Note that the priority semantics have not yet been fleshed out and 403 Note that the priority semantics have not yet been fleshed out and
204 are subject to almost certain change. 404 are subject to almost certain change.
205 405
206 $w->trigger ($revents) 406 $w->invoke ($revents)
207 Call the callback *now* with the given event mask. 407 Call the callback *now* with the given event mask.
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.
208 417
209 $previous_state = $w->keepalive ($bool) 418 $previous_state = $w->keepalive ($bool)
210 Normally, "EV::loop" will return when there are no active watchers 419 Normally, "EV::loop" will return when there are no active watchers
211 (which is a "deadlock" because no progress can be made anymore). 420 (which is a "deadlock" because no progress can be made anymore).
212 This is convinient because it allows you to start your watchers (and 421 This is convenient because it allows you to start your watchers (and
213 your jobs), call "EV::loop" once and when it returns you know that 422 your jobs), call "EV::loop" once and when it returns you know that
214 all your jobs are finished (or they forgot to register some watchers 423 all your jobs are finished (or they forgot to register some watchers
215 for their task :). 424 for their task :).
216 425
217 Sometimes, however, this gets in your way, for example when you the 426 Sometimes, however, this gets in your way, for example when the
218 module that calls "EV::loop" (usually the main program) is not the 427 module that calls "EV::loop" (usually the main program) is not the
219 same module as a long-living watcher (for example a DNS client 428 same module as a long-living watcher (for example a DNS client
220 module written by somebody else even). Then you might want any 429 module written by somebody else even). Then you might want any
221 outstanding requests to be handled, but you would not want to keep 430 outstanding requests to be handled, but you would not want to keep
222 "EV::loop" from returning just because you happen to have this 431 "EV::loop" from returning just because you happen to have this
… …
224 433
225 In this case you can clear the keepalive status, which means that 434 In this case you can clear the keepalive status, which means that
226 even though your watcher is active, it won't keep "EV::loop" from 435 even though your watcher is active, it won't keep "EV::loop" from
227 returning. 436 returning.
228 437
229 The initial value for keepalive is true (enabled), and you cna 438 The initial value for keepalive is true (enabled), and you can
230 change it any time. 439 change it any time.
231 440
232 Example: Register an IO watcher for some UDP socket but do not keep 441 Example: Register an I/O watcher for some UDP socket but do not keep
233 the event loop from running just because of that watcher. 442 the event loop from running just because of that watcher.
234 443
235 my $udp_socket = ... 444 my $udp_socket = ...
236 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 445 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
237 $udp_watcher->keepalive (0); 446 $udp_watcher->keepalive (0);
238 447
448 $loop = $w->loop
449 Return the loop that this watcher is attached to.
450
239 WATCHER TYPES 451WATCHER TYPES
240 Each of the following subsections describes a single watcher type. 452 Each of the following subsections describes a single watcher type.
241 453
242 IO WATCHERS - is this file descriptor readable or writable? 454 I/O WATCHERS - is this file descriptor readable or writable?
243 $w = EV::io $fileno_or_fh, $eventmask, $callback 455 $w = EV::io $fileno_or_fh, $eventmask, $callback
244 $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)
245 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
246 when at least one of events specified in $eventmask occurs. 460 when at least one of events specified in $eventmask occurs.
247 461
248 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:
249 463
… …
266 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.
267 481
268 TIMER WATCHERS - relative and optionally repeating timeouts 482 TIMER WATCHERS - relative and optionally repeating timeouts
269 $w = EV::timer $after, $repeat, $callback 483 $w = EV::timer $after, $repeat, $callback
270 $w = EV::timer_ns $after, $repeat, $callback 484 $w = EV::timer_ns $after, $repeat, $callback
485 $w = $loop->timer ($after, $repeat, $callback)
486 $w = $loop->timer_ns ($after, $repeat, $callback)
271 Calls the callback after $after seconds (which may be fractional). 487 Calls the callback after $after seconds (which may be fractional).
272 If $repeat is non-zero, the timer will be restarted (with the 488 If $repeat is non-zero, the timer will be restarted (with the
273 $repeat value as $after) after the callback returns. 489 $repeat value as $after) after the callback returns.
274 490
275 This means that the callback would be called roughly after $after 491 This means that the callback would be called roughly after $after
… …
311 method on the timeout. 527 method on the timeout.
312 528
313 PERIODIC WATCHERS - to cron or not to cron? 529 PERIODIC WATCHERS - to cron or not to cron?
314 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 530 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
315 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 531 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
532 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
533 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
316 Similar to EV::timer, but is not based on relative timeouts but on 534 Similar to EV::timer, but is not based on relative timeouts but on
317 absolute times. Apart from creating "simple" timers that trigger 535 absolute times. Apart from creating "simple" timers that trigger
318 "at" the specified time, it can also be used for non-drifting 536 "at" the specified time, it can also be used for non-drifting
319 absolute timers and more complex, cron-like, setups that are not 537 absolute timers and more complex, cron-like, setups that are not
320 adversely affected by time jumps (i.e. when the system clock is 538 adversely affected by time jumps (i.e. when the system clock is
321 changed by explicit date -s or other means such as ntpd). It is also 539 changed by explicit date -s or other means such as ntpd). It is also
322 the most complex watcher type in EV. 540 the most complex watcher type in EV.
323 541
324 It has three distinct "modes": 542 It has three distinct "modes":
325 543
326 * absolute timer ($interval = $reschedule_cb = 0) 544 * absolute timer ($interval = $reschedule_cb = 0)
545
327 This time simply fires at the wallclock time $at and doesn't 546 This time simply fires at the wallclock time $at and doesn't
328 repeat. It will not adjust when a time jump occurs, that is, if 547 repeat. It will not adjust when a time jump occurs, that is, if
329 it is to be run at January 1st 2011 then it will run when the 548 it is to be run at January 1st 2011 then it will run when the
330 system time reaches or surpasses this time. 549 system time reaches or surpasses this time.
331 550
332 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 551 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
552
333 In this mode the watcher will always be scheduled to time out at 553 In this mode the watcher will always be scheduled to time out at
334 the next "$at + N * $interval" time (for some integer N) and 554 the next "$at + N * $interval" time (for some integer N) and
335 then repeat, regardless of any time jumps. 555 then repeat, regardless of any time jumps.
336 556
337 This can be used to create timers that do not drift with respect 557 This can be used to create timers that do not drift with respect
338 to system time: 558 to system time:
339 559
340 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; 560 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
341 561
342 That doesn't mean there will always be 3600 seconds in between 562 That doesn't mean there will always be 3600 seconds in between
343 triggers, but only that the the clalback will be called when the 563 triggers, but only that the the callback will be called when the
344 system time shows a full hour (UTC). 564 system time shows a full hour (UTC).
345 565
346 Another way to think about it (for the mathematically inclined) 566 Another way to think about it (for the mathematically inclined)
347 is that EV::periodic will try to run the callback in this mode 567 is that EV::periodic will try to run the callback in this mode
348 at the next possible time where "$time = $at (mod $interval)", 568 at the next possible time where "$time = $at (mod $interval)",
349 regardless of any time jumps. 569 regardless of any time jumps.
350 570
351 * manual reschedule mode ($reschedule_cb = coderef) 571 * manual reschedule mode ($reschedule_cb = coderef)
572
352 In this mode $interval and $at are both being ignored. Instead, 573 In this mode $interval and $at are both being ignored. Instead,
353 each time the periodic watcher gets scheduled, the reschedule 574 each time the periodic watcher gets scheduled, the reschedule
354 callback ($reschedule_cb) will be called with the watcher as 575 callback ($reschedule_cb) will be called with the watcher as
355 first, and the current time as second argument. 576 first, and the current time as second argument.
356 577
357 *This callback MUST NOT stop or destroy this or any other 578 *This callback MUST NOT stop or destroy this or any other
579 periodic watcher, ever, and MUST NOT call any event loop
358 periodic watcher, ever*. If you need to stop it, return 1e30 and 580 functions or methods*. If you need to stop it, return 1e30 and
359 stop it afterwards. 581 stop it afterwards. You may create and start a "EV::prepare"
582 watcher for this task.
360 583
361 It must return the next time to trigger, based on the passed 584 It must return the next time to trigger, based on the passed
362 time value (that is, the lowest time value larger than to the 585 time value (that is, the lowest time value larger than or equal
363 second argument). It will usually be called just before the 586 to to the second argument). It will usually be called just
364 callback will be triggered, but might be called at other times, 587 before the callback will be triggered, but might be called at
365 too. 588 other times, too.
366 589
367 This can be used to create very complex timers, such as a timer 590 This can be used to create very complex timers, such as a timer
368 that triggers on each midnight, local time (actually 24 hours 591 that triggers on each midnight, local time (actually 24 hours
369 after the last midnight, to keep the example simple. If you know 592 after the last midnight, to keep the example simple. If you know
370 a way to do it correctly in about the same space (without 593 a way to do it correctly in about the same space (without
… …
388 be called at any time. 611 be called at any time.
389 612
390 $w->again 613 $w->again
391 Simply stops and starts the watcher again. 614 Simply stops and starts the watcher again.
392 615
616 $time = $w->at
617 Return the time that the watcher is expected to trigger next.
618
393 SIGNAL WATCHERS - signal me when a signal gets signalled! 619 SIGNAL WATCHERS - signal me when a signal gets signalled!
394 $w = EV::signal $signal, $callback 620 $w = EV::signal $signal, $callback
395 $w = EV::signal_ns $signal, $callback 621 $w = EV::signal_ns $signal, $callback
622 $w = $loop->signal ($signal, $callback)
623 $w = $loop->signal_ns ($signal, $callback)
396 Call the callback when $signal is received (the signal can be 624 Call the callback when $signal is received (the signal can be
397 specified by number or by name, just as with "kill" or %SIG). 625 specified by number or by name, just as with "kill" or %SIG).
626
627 Only one event loop can grab a given signal - attempting to grab the
628 same signal from two EV loops will crash the program immediately or
629 cause data corruption.
398 630
399 EV will grab the signal for the process (the kernel only allows one 631 EV will grab the signal for the process (the kernel only allows one
400 component to receive a signal at a time) when you start a signal 632 component to receive a signal at a time) when you start a signal
401 watcher, and removes it again when you stop it. Perl does the same 633 watcher, and removes it again when you stop it. Perl does the same
402 when you add/remove callbacks to %SIG, so watch out. 634 when you add/remove callbacks to %SIG, so watch out.
… …
414 $old_signum = $w->signal ($new_signal) 646 $old_signum = $w->signal ($new_signal)
415 Returns the previously set signal (always as a number not name) and 647 Returns the previously set signal (always as a number not name) and
416 optionally set a new one. 648 optionally set a new one.
417 649
418 CHILD WATCHERS - watch out for process status changes 650 CHILD WATCHERS - watch out for process status changes
419 $w = EV::child $pid, $callback 651 $w = EV::child $pid, $trace, $callback
420 $w = EV::child_ns $pid, $callback 652 $w = EV::child_ns $pid, $trace, $callback
653 $w = $loop->child ($pid, $trace, $callback)
654 $w = $loop->child_ns ($pid, $trace, $callback)
421 Call the callback when a status change for pid $pid (or any pid if 655 Call the callback when a status change for pid $pid (or any pid if
422 $pid is 0) has been received. More precisely: when the process 656 $pid is 0) has been received (a status change happens when the
657 process terminates or is killed, or, when trace is true,
658 additionally when it is stopped or continued). More precisely: when
423 receives a "SIGCHLD", EV will fetch the outstanding exit/wait status 659 the process receives a "SIGCHLD", EV will fetch the outstanding
424 for all changed/zombie children and call the callback. 660 exit/wait status for all changed/zombie children and call the
661 callback.
425 662
426 It is valid (and fully supported) to install a child watcher after a 663 It is valid (and fully supported) to install a child watcher after a
427 child has exited but before the event loop has started its next 664 child has exited but before the event loop has started its next
428 iteration (for example, first you "fork", then the new child process 665 iteration (for example, first you "fork", then the new child process
429 might exit, and only then do you install a child watcher in the 666 might exit, and only then do you install a child watcher in the
… …
436 be called. 673 be called.
437 674
438 The "child_ns" variant doesn't start (activate) the newly created 675 The "child_ns" variant doesn't start (activate) the newly created
439 watcher. 676 watcher.
440 677
441 $w->set ($pid) 678 $w->set ($pid, $trace)
442 Reconfigures the watcher, see the constructor above for details. Can 679 Reconfigures the watcher, see the constructor above for details. Can
443 be called at any time. 680 be called at any time.
444 681
445 $current_pid = $w->pid 682 $current_pid = $w->pid
446 $old_pid = $w->pid ($new_pid)
447 Returns the previously set process id and optionally set a new one. 683 Returns the previously set process id and optionally set a new one.
448 684
449 $exit_status = $w->rstatus 685 $exit_status = $w->rstatus
450 Return the exit/wait status (as returned by waitpid, see the waitpid 686 Return the exit/wait status (as returned by waitpid, see the waitpid
451 entry in perlfunc). 687 entry in perlfunc).
… …
455 a watcher for all pids). 691 a watcher for all pids).
456 692
457 STAT WATCHERS - did the file attributes just change? 693 STAT WATCHERS - did the file attributes just change?
458 $w = EV::stat $path, $interval, $callback 694 $w = EV::stat $path, $interval, $callback
459 $w = EV::stat_ns $path, $interval, $callback 695 $w = EV::stat_ns $path, $interval, $callback
696 $w = $loop->stat ($path, $interval, $callback)
697 $w = $loop->stat_ns ($path, $interval, $callback)
460 Call the callback when a file status change has been detected on 698 Call the callback when a file status change has been detected on
461 $path. The $path does not need to exist, changing from "path exists" 699 $path. The $path does not need to exist, changing from "path exists"
462 to "path does not exist" is a status change like any other. 700 to "path does not exist" is a status change like any other.
463 701
464 The $interval is a recommended polling interval for systems where 702 The $interval is a recommended polling interval for systems where
… …
524 Can be used to query the actual interval used. 762 Can be used to query the actual interval used.
525 763
526 IDLE WATCHERS - when you've got nothing better to do... 764 IDLE WATCHERS - when you've got nothing better to do...
527 $w = EV::idle $callback 765 $w = EV::idle $callback
528 $w = EV::idle_ns $callback 766 $w = EV::idle_ns $callback
767 $w = $loop->idle ($callback)
768 $w = $loop->idle_ns ($callback)
529 Call the callback when there are no pending io, timer/periodic, 769 Call the callback when there are no other pending watchers of the
530 signal or child events, i.e. when the process is idle. 770 same or higher priority (excluding check, prepare and other idle
771 watchers of the same or lower priority, of course). They are called
772 idle watchers because when the watcher is the highest priority
773 pending event in the process, the process is considered to be idle
774 at that priority.
775
776 If you want a watcher that is only ever called when *no* other
777 events are outstanding you have to set the priority to "EV::MINPRI".
531 778
532 The process will not block as long as any idle watchers are active, 779 The process will not block as long as any idle watchers are active,
533 and they will be called repeatedly until stopped. 780 and they will be called repeatedly until stopped.
781
782 For example, if you have idle watchers at priority 0 and 1, and an
783 I/O watcher at priority 0, then the idle watcher at priority 1 and
784 the I/O watcher will always run when ready. Only when the idle
785 watcher at priority 1 is stopped and the I/O watcher at priority 0
786 is not pending with the 0-priority idle watcher be invoked.
534 787
535 The "idle_ns" variant doesn't start (activate) the newly created 788 The "idle_ns" variant doesn't start (activate) the newly created
536 watcher. 789 watcher.
537 790
538 PREPARE WATCHERS - customise your event loop! 791 PREPARE WATCHERS - customise your event loop!
539 $w = EV::prepare $callback 792 $w = EV::prepare $callback
540 $w = EV::prepare_ns $callback 793 $w = EV::prepare_ns $callback
794 $w = $loop->prepare ($callback)
795 $w = $loop->prepare_ns ($callback)
541 Call the callback just before the process would block. You can still 796 Call the callback just before the process would block. You can still
542 create/modify any watchers at this point. 797 create/modify any watchers at this point.
543 798
544 See the EV::check watcher, below, for explanations and an example. 799 See the EV::check watcher, below, for explanations and an example.
545 800
… …
547 watcher. 802 watcher.
548 803
549 CHECK WATCHERS - customise your event loop even more! 804 CHECK WATCHERS - customise your event loop even more!
550 $w = EV::check $callback 805 $w = EV::check $callback
551 $w = EV::check_ns $callback 806 $w = EV::check_ns $callback
807 $w = $loop->check ($callback)
808 $w = $loop->check_ns ($callback)
552 Call the callback just after the process wakes up again (after it 809 Call the callback just after the process wakes up again (after it
553 has gathered events), but before any other callbacks have been 810 has gathered events), but before any other callbacks have been
554 invoked. 811 invoked.
555 812
556 This is used to integrate other event-based software into the EV 813 This can be used to integrate other event-based software into the EV
557 mainloop: You register a prepare callback and in there, you create 814 mainloop: You register a prepare callback and in there, you create
558 io and timer watchers as required by the other software. Here is a 815 io and timer watchers as required by the other software. Here is a
559 real-world example of integrating Net::SNMP (with some details left 816 real-world example of integrating Net::SNMP (with some details left
560 out): 817 out):
561 818
… …
567 or return; 824 or return;
568 825
569 # make the dispatcher handle any outstanding stuff 826 # make the dispatcher handle any outstanding stuff
570 ... not shown 827 ... not shown
571 828
572 # create an IO watcher for each and every socket 829 # create an I/O watcher for each and every socket
573 @snmp_watcher = ( 830 @snmp_watcher = (
574 (map { EV::io $_, EV::READ, sub { } } 831 (map { EV::io $_, EV::READ, sub { } }
575 keys %{ $dispatcher->{_descriptors} }), 832 keys %{ $dispatcher->{_descriptors} }),
576 833
577 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 834 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
… …
592 # make the dispatcher handle any new stuff 849 # make the dispatcher handle any new stuff
593 ... not shown 850 ... not shown
594 }; 851 };
595 852
596 The callbacks of the created watchers will not be called as the 853 The callbacks of the created watchers will not be called as the
597 watchers are destroyed before this cna happen (remember EV::check 854 watchers are destroyed before this can happen (remember EV::check
598 gets called first). 855 gets called first).
599 856
600 The "check_ns" variant doesn't start (activate) the newly created 857 The "check_ns" variant doesn't start (activate) the newly created
601 watcher. 858 watcher.
859
860 EV::CHECK constant issues
861 Like all other watcher types, there is a bitmask constant for use in
862 $revents and other places. The "EV::CHECK" is special as it has the
863 same name as the "CHECK" sub called by Perl. This doesn't cause big
864 issues on newer perls (beginning with 5.8.9), but it means thatthe
865 constant must be *inlined*, i.e. runtime calls will not work. That
866 means that as long as you always "use EV" and then "EV::CHECK" you
867 are on the safe side.
602 868
603 FORK WATCHERS - the audacity to resume the event loop after a fork 869 FORK WATCHERS - the audacity to resume the event loop after a fork
604 Fork watchers are called when a "fork ()" was detected. The invocation 870 Fork watchers are called when a "fork ()" was detected. The invocation
605 is done before the event loop blocks next and before "check" watchers 871 is done before the event loop blocks next and before "check" watchers
606 are being called, and only in the child after the fork. 872 are being called, and only in the child after the fork.
607 873
608 $w = EV::fork $callback 874 $w = EV::fork $callback
609 $w = EV::fork_ns $callback 875 $w = EV::fork_ns $callback
876 $w = $loop->fork ($callback)
877 $w = $loop->fork_ns ($callback)
610 Call the callback before the event loop is resumed in the child 878 Call the callback before the event loop is resumed in the child
611 process after a fork. 879 process after a fork.
612 880
613 The "fork_ns" variant doesn't start (activate) the newly created 881 The "fork_ns" variant doesn't start (activate) the newly created
614 watcher. 882 watcher.
615 883
884 EMBED WATCHERS - when one backend isn't enough...
885 This is a rather advanced watcher type that lets you embed one event
886 loop into another (currently only IO events are supported in the
887 embedded loop, other types of watchers might be handled in a delayed or
888 incorrect fashion and must not be used).
889
890 See the libev documentation at
891 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
892 _when_one_backend_> (locally installed as EV::libev) for more details.
893
894 In short, this watcher is most useful on BSD systems without working
895 kqueue to still be able to handle a large number of sockets:
896
897 my $socket_loop;
898
899 # check wether we use SELECT or POLL _and_ KQUEUE is supported
900 if (
901 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
902 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
903 ) {
904 # use kqueue for sockets
905 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
906 }
907
908 # use the default loop otherwise
909 $socket_loop ||= EV::default_loop;
910
911 $w = EV::embed $otherloop[, $callback]
912 $w = EV::embed_ns $otherloop[, $callback]
913 $w = $loop->embed ($otherloop[, $callback])
914 $w = $loop->embed_ns ($otherloop[, $callback])
915 Call the callback when the embedded event loop ($otherloop) has any
916 I/O activity. The $callback is optional: if it is missing, then the
917 embedded event loop will be managed automatically (which is
918 recommended), otherwise you have to invoke "sweep" yourself.
919
920 The "embed_ns" variant doesn't start (activate) the newly created
921 watcher.
922
923 ASYNC WATCHERS - how to wake up another event loop
924 Async watchers are provided by EV, but have little use in perl directly,
925 as perl neither supports threads running in parallel nor direct access
926 to signal handlers or other contexts where they could be of value.
927
928 It is, however, possible to use them from the XS level.
929
930 Please see the libev documentation for further details.
931
932 $w = EV::async $callback
933 $w = EV::async_ns $callback
934 $w = $loop->async ($callback)
935 $w = $loop->async_ns ($callback)
936 $w->send
937 $bool = $w->async_pending
938
939 CLEANUP WATCHERS - how to clean up when the event loop goes away
940 Cleanup watchers are not supported on the Perl level, they can only be
941 used via XS currently.
942
943PERL SIGNALS
944 While Perl signal handling (%SIG) is not affected by EV, the behaviour
945 with EV is as the same as any other C library: Perl-signals will only be
946 handled when Perl runs, which means your signal handler might be invoked
947 only the next time an event callback is invoked.
948
949 The solution is to use EV signal watchers (see "EV::signal"), which will
950 ensure proper operations with regards to other event watchers.
951
952 If you cannot do this for whatever reason, you can also force a watcher
953 to be called on every event loop iteration by installing a "EV::check"
954 watcher:
955
956 my $async_check = EV::check sub { };
957
958 This ensures that perl gets into control for a short time to handle any
959 pending signals, and also ensures (slightly) slower overall operation.
960
616THREADS 961ITHREADS
617 Threads are not supported by this module in any way. Perl pseudo-threads 962 Ithreads are not supported by this module in any way. Perl
618 is evil stuff and must die. As soon as Perl gains real threads I will 963 pseudo-threads is evil stuff and must die. Real threads as provided by
619 work on thread support for it. 964 Coro are fully supported (and enhanced support is available via
965 Coro::EV).
620 966
621FORK 967FORK
622 Most of the "improved" event delivering mechanisms of modern operating 968 Most of the "improved" event delivering mechanisms of modern operating
623 systems have quite a few problems with fork(2) (to put it bluntly: it is 969 systems have quite a few problems with fork(2) (to put it bluntly: it is
624 not supported and usually destructive). Libev makes it possible to work 970 not supported and usually destructive). Libev makes it possible to work
… …
634 980
635 On win32, there is no notion of fork so all this doesn't apply, of 981 On win32, there is no notion of fork so all this doesn't apply, of
636 course. 982 course.
637 983
638SEE ALSO 984SEE ALSO
639 EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event 985 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
640 loop), Coro::EV (efficient coroutines with EV). 986 DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed
987 Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV
988 (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event
989 driven programming.
641 990
642AUTHOR 991AUTHOR
643 Marc Lehmann <schmorp@schmorp.de> 992 Marc Lehmann <schmorp@schmorp.de>
644 http://home.schmorp.de/ 993 http://home.schmorp.de/
645 994

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