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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 44 # STAT CHANGES
38 45 my $w = EV::stat "/etc/passwd", 10, sub {
39 my $w = EV::child 666, sub {
40 my ($w, $revents) = @_; 46 my ($w, $revents) = @_;
41 my $status = $w->rstatus; 47 warn $w->path, " has changed somehow.\n";
42 }; 48 };
43 49
44 # MAINLOOP 50 # MAINLOOP
45 EV::loop; # loop until EV::unloop is called or all watchers stop 51 EV::loop; # loop until EV::unloop is called or all watchers stop
46 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 52 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
47 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 53 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
54
55BEFORE YOU START USING THIS MODULE
56 If you only need timer, I/O, signal, child and idle watchers and not the
57 advanced functionality of this module, consider using AnyEvent instead,
58 specifically the simplified API described in AE.
59
60 When used with EV as backend, the AE API is as fast as the native EV
61 API, but your programs/modules will still run with many other event
62 loops.
48 63
49DESCRIPTION 64DESCRIPTION
50 This module provides an interface to libev 65 This module provides an interface to libev
51 (<http://software.schmorp.de/pkg/libev.html>). While the documentation 66 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
52 below is comprehensive, one might also consult the documentation of 67 below is comprehensive, one might also consult the documentation of
53 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
54 details on watcher semantics or some discussion on the available 69 perldoc EV::libev) for more subtle details on watcher semantics or some
55 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->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.
56 167
57BASIC INTERFACE 168BASIC INTERFACE
58 $EV::DIED 169 $EV::DIED
59 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
60 callback throws an exception (with $@ containing thr error). The 171 callback throws an exception (with $@ containing the error). The
61 default prints an informative message and continues. 172 default prints an informative message and continues.
62 173
63 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.
64 186
65 $time = EV::time 187 $time = EV::time
66 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
67 189
68 $time = EV::now 190 $time = EV::now
191 $time = $loop->now
69 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
70 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
71 to it is usually faster then calling EV::time. 194 to it is usually faster then calling EV::time.
72 195
73 $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 = $loop->backend
74 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
75 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
76 237
77 EV::loop [$flags] 238 EV::loop [$flags]
239 $loop->loop ([$flags])
78 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
79 callback calls EV::unloop. 241 callback calls EV::unloop.
80 242
81 The $flags argument can be one of the following: 243 The $flags argument can be one of the following:
82 244
83 0 as above 245 0 as above
84 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 246 EV::LOOP_ONCE block at most once (wait, but do not loop)
85 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 247 EV::LOOP_NOWAIT do not block at all (fetch/handle events but do not wait)
86 248
87 EV::unloop [$how] 249 EV::break [$how]
250 $loop->break ([$how])
88 When called with no arguments or an argument of EV::UNLOOP_ONE, 251 When called with no arguments or an argument of EV::BREAK_ONE, makes
89 makes the innermost call to EV::loop return. 252 the innermost call to EV::loop return.
90 253
91 When called with an argument of EV::UNLOOP_ALL, all calls to 254 When called with an argument of EV::BREAK_ALL, all calls to EV::loop
92 EV::loop will return as fast as possible. 255 will return as fast as possible.
256
257 When called with an argument of EV::BREAK_CANCEL, any pending break
258 will be cancelled.
259
260 $count = EV::loop_count
261 $count = $loop->loop_count
262 Return the number of times the event loop has polled for new events.
263 Sometimes useful as a generation counter.
93 264
94 EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 265 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
266 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
95 This function rolls together an I/O and a timer watcher for a single 267 This function rolls together an I/O and a timer watcher for a single
96 one-shot event without the need for managing a watcher object. 268 one-shot event without the need for managing a watcher object.
97 269
98 If $fh_or_undef is a filehandle or file descriptor, then $events 270 If $fh_or_undef is a filehandle or file descriptor, then $events
99 must be a bitset containing either "EV::READ", "EV::WRITE" or 271 must be a bitset containing either "EV::READ", "EV::WRITE" or
… …
104 If timeout is "undef" or negative, then there will be no timeout. 276 If timeout is "undef" or negative, then there will be no timeout.
105 Otherwise a EV::timer with this value will be started. 277 Otherwise a EV::timer with this value will be started.
106 278
107 When an error occurs or either the timeout or I/O watcher triggers, 279 When an error occurs or either the timeout or I/O watcher triggers,
108 then the callback will be called with the received event set (in 280 then the callback will be called with the received event set (in
109 general you can expect it to be a combination of "EV:ERROR", 281 general you can expect it to be a combination of "EV::ERROR",
110 "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). 282 "EV::READ", "EV::WRITE" and "EV::TIMER").
111 283
112 EV::once doesn't return anything: the watchers stay active till 284 EV::once doesn't return anything: the watchers stay active till
113 either of them triggers, then they will be stopped and freed, and 285 either of them triggers, then they will be stopped and freed, and
114 the callback invoked. 286 the callback invoked.
115 287
116 WATCHER 288 EV::feed_fd_event $fd, $revents
289 $loop->feed_fd_event ($fd, $revents)
290 Feed an event on a file descriptor into EV. EV will react to this
291 call as if the readyness notifications specified by $revents (a
292 combination of "EV::READ" and "EV::WRITE") happened on the file
293 descriptor $fd.
294
295 EV::feed_signal_event $signal
296 Feed a signal event into the default loop. EV will react to this
297 call as if the signal specified by $signal had occured.
298
299 EV::feed_signal $signal
300 Feed a signal event into EV - unlike "EV::feed_signal_event", this
301 works regardless of which loop has registered the signal, and is
302 mainly useful fro custom signal implementations.
303
304 EV::set_io_collect_interval $time
305 $loop->set_io_collect_interval ($time)
306 EV::set_timeout_collect_interval $time
307 $loop->set_timeout_collect_interval ($time)
308 These advanced functions set the minimum block interval when polling
309 for I/O events and the minimum wait interval for timer events. See
310 the libev documentation at
311 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
312 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
313 detailed discussion.
314
315 $count = EV::pending_count
316 $count = $loop->pending_count
317 Returns the number of currently pending watchers.
318
319 EV::invoke_pending
320 $loop->invoke_pending
321 Invoke all currently pending watchers.
322
323WATCHER OBJECTS
117 A watcher is an object that gets created to record your interest in some 324 A watcher is an object that gets created to record your interest in some
118 event. For instance, if you want to wait for STDIN to become readable, 325 event. For instance, if you want to wait for STDIN to become readable,
119 you would create an EV::io watcher for that: 326 you would create an EV::io watcher for that:
120 327
121 my $watcher = EV::io *STDIN, EV::READ, sub { 328 my $watcher = EV::io *STDIN, EV::READ, sub {
122 my ($watcher, $revents) = @_; 329 my ($watcher, $revents) = @_;
123 warn "yeah, STDIN should not be readable without blocking!\n" 330 warn "yeah, STDIN should now be readable without blocking!\n"
124 }; 331 };
125 332
126 All watchers can be active (waiting for events) or inactive (paused). 333 All watchers can be active (waiting for events) or inactive (paused).
127 Only active watchers will have their callbacks invoked. All callbacks 334 Only active watchers will have their callbacks invoked. All callbacks
128 will be called with at least two arguments: the watcher and a bitmask of 335 will be called with at least two arguments: the watcher and a bitmask of
129 received events. 336 received events.
130 337
131 Each watcher type has its associated bit in revents, so you can use the 338 Each watcher type has its associated bit in revents, so you can use the
132 same callback for multiple watchers. The event mask is named after the 339 same callback for multiple watchers. The event mask is named after the
133 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 340 type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
134 EV::periodic sets EV::PERIODIC and so on, with the exception of IO 341 EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
135 events (which can set both EV::READ and EV::WRITE bits), and EV::timer 342 events (which can set both EV::READ and EV::WRITE bits).
136 (which uses EV::TIMEOUT).
137 343
138 In the rare case where one wants to create a watcher but not start it at 344 In the rare case where one wants to create a watcher but not start it at
139 the same time, each constructor has a variant with a trailing "_ns" in 345 the same time, each constructor has a variant with a trailing "_ns" in
140 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 346 its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
141 347
… …
145 351
146 Also, all methods changing some aspect of a watcher (->set, ->priority, 352 Also, all methods changing some aspect of a watcher (->set, ->priority,
147 ->fh and so on) automatically stop and start it again if it is active, 353 ->fh and so on) automatically stop and start it again if it is active,
148 which means pending events get lost. 354 which means pending events get lost.
149 355
150 WATCHER TYPES 356 COMMON WATCHER METHODS
151 Now lets move to the existing watcher types and asociated methods. 357 This section lists methods common to all watchers.
152
153 The following methods are available for all watchers. Then followes a
154 description of each watcher constructor (EV::io, EV::timer,
155 EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and
156 EV::check), followed by any type-specific methods (if any).
157 358
158 $w->start 359 $w->start
159 Starts a watcher if it isn't active already. Does nothing to an 360 Starts a watcher if it isn't active already. Does nothing to an
160 already active watcher. By default, all watchers start out in the 361 already active watcher. By default, all watchers start out in the
161 active state (see the description of the "_ns" variants if you need 362 active state (see the description of the "_ns" variants if you need
162 stopped watchers). 363 stopped watchers).
163 364
164 $w->stop 365 $w->stop
165 Stop a watcher if it is active. Also clear any pending events 366 Stop a watcher if it is active. Also clear any pending events
166 (events that have been received but that didn't yet result in a 367 (events that have been received but that didn't yet result in a
167 callback invocation), regardless of wether the watcher was active or 368 callback invocation), regardless of whether the watcher was active
168 not. 369 or not.
169 370
170 $bool = $w->is_active 371 $bool = $w->is_active
171 Returns true if the watcher is active, false otherwise. 372 Returns true if the watcher is active, false otherwise.
172 373
173 $current_data = $w->data 374 $current_data = $w->data
… …
196 The default priority of any newly-created watcher is 0. 397 The default priority of any newly-created watcher is 0.
197 398
198 Note that the priority semantics have not yet been fleshed out and 399 Note that the priority semantics have not yet been fleshed out and
199 are subject to almost certain change. 400 are subject to almost certain change.
200 401
201 $w->trigger ($revents) 402 $w->invoke ($revents)
202 Call the callback *now* with the given event mask. 403 Call the callback *now* with the given event mask.
404
405 $w->feed_event ($revents)
406 Feed some events on this watcher into EV. EV will react to this call
407 as if the watcher had received the given $revents mask.
408
409 $revents = $w->clear_pending
410 If the watcher is pending, this function clears its pending status
411 and returns its $revents bitset (as if its callback was invoked). If
412 the watcher isn't pending it does nothing and returns 0.
203 413
204 $previous_state = $w->keepalive ($bool) 414 $previous_state = $w->keepalive ($bool)
205 Normally, "EV::loop" will return when there are no active watchers 415 Normally, "EV::loop" will return when there are no active watchers
206 (which is a "deadlock" because no progress can be made anymore). 416 (which is a "deadlock" because no progress can be made anymore).
207 This is convinient because it allows you to start your watchers (and 417 This is convenient because it allows you to start your watchers (and
208 your jobs), call "EV::loop" once and when it returns you know that 418 your jobs), call "EV::loop" once and when it returns you know that
209 all your jobs are finished (or they forgot to register some watchers 419 all your jobs are finished (or they forgot to register some watchers
210 for their task :). 420 for their task :).
211 421
212 Sometimes, however, this gets in your way, for example when you the 422 Sometimes, however, this gets in your way, for example when the
213 module that calls "EV::loop" (usually the main program) is not the 423 module that calls "EV::loop" (usually the main program) is not the
214 same module as a long-living watcher (for example a DNS client 424 same module as a long-living watcher (for example a DNS client
215 module written by somebody else even). Then you might want any 425 module written by somebody else even). Then you might want any
216 outstanding requests to be handled, but you would not want to keep 426 outstanding requests to be handled, but you would not want to keep
217 "EV::loop" from returning just because you happen to have this 427 "EV::loop" from returning just because you happen to have this
… …
219 429
220 In this case you can clear the keepalive status, which means that 430 In this case you can clear the keepalive status, which means that
221 even though your watcher is active, it won't keep "EV::loop" from 431 even though your watcher is active, it won't keep "EV::loop" from
222 returning. 432 returning.
223 433
224 The initial value for keepalive is true (enabled), and you cna 434 The initial value for keepalive is true (enabled), and you can
225 change it any time. 435 change it any time.
226 436
227 Example: Register an IO watcher for some UDP socket but do not keep 437 Example: Register an I/O watcher for some UDP socket but do not keep
228 the event loop from running just because of that watcher. 438 the event loop from running just because of that watcher.
229 439
230 my $udp_socket = ... 440 my $udp_socket = ...
231 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 441 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
232 $udp_watcher->keepalive (0); 442 $udp_watcher->keepalive (0);
233 443
444 $loop = $w->loop
445 Return the loop that this watcher is attached to.
446
447WATCHER TYPES
448 Each of the following subsections describes a single watcher type.
449
450 I/O WATCHERS - is this file descriptor readable or writable?
234 $w = EV::io $fileno_or_fh, $eventmask, $callback 451 $w = EV::io $fileno_or_fh, $eventmask, $callback
235 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 452 $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
453 $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
454 $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
236 As long as the returned watcher object is alive, call the $callback 455 As long as the returned watcher object is alive, call the $callback
237 when the events specified in $eventmask. 456 when at least one of events specified in $eventmask occurs.
238 457
239 The $eventmask can be one or more of these constants ORed together: 458 The $eventmask can be one or more of these constants ORed together:
240 459
241 EV::READ wait until read() wouldn't block anymore 460 EV::READ wait until read() wouldn't block anymore
242 EV::WRITE wait until write() wouldn't block anymore 461 EV::WRITE wait until write() wouldn't block anymore
… …
254 473
255 $current_eventmask = $w->events 474 $current_eventmask = $w->events
256 $old_eventmask = $w->events ($new_eventmask) 475 $old_eventmask = $w->events ($new_eventmask)
257 Returns the previously set event mask and optionally set a new one. 476 Returns the previously set event mask and optionally set a new one.
258 477
478 TIMER WATCHERS - relative and optionally repeating timeouts
259 $w = EV::timer $after, $repeat, $callback 479 $w = EV::timer $after, $repeat, $callback
260 $w = EV::timer_ns $after, $repeat, $callback 480 $w = EV::timer_ns $after, $repeat, $callback
481 $w = $loop->timer ($after, $repeat, $callback)
482 $w = $loop->timer_ns ($after, $repeat, $callback)
261 Calls the callback after $after seconds (which may be fractional). 483 Calls the callback after $after seconds (which may be fractional).
262 If $repeat is non-zero, the timer will be restarted (with the 484 If $repeat is non-zero, the timer will be restarted (with the
263 $repeat value as $after) after the callback returns. 485 $repeat value as $after) after the callback returns.
264 486
265 This means that the callback would be called roughly after $after 487 This means that the callback would be called roughly after $after
… …
277 The "timer_ns" variant doesn't start (activate) the newly created 499 The "timer_ns" variant doesn't start (activate) the newly created
278 watcher. 500 watcher.
279 501
280 $w->set ($after, $repeat) 502 $w->set ($after, $repeat)
281 Reconfigures the watcher, see the constructor above for details. Can 503 Reconfigures the watcher, see the constructor above for details. Can
282 be at any time. 504 be called at any time.
283 505
284 $w->again 506 $w->again
285 Similar to the "start" method, but has special semantics for 507 Similar to the "start" method, but has special semantics for
286 repeating timers: 508 repeating timers:
287 509
… …
298 This behaviour is useful when you have a timeout for some IO 520 This behaviour is useful when you have a timeout for some IO
299 operation. You create a timer object with the same value for $after 521 operation. You create a timer object with the same value for $after
300 and $repeat, and then, in the read/write watcher, run the "again" 522 and $repeat, and then, in the read/write watcher, run the "again"
301 method on the timeout. 523 method on the timeout.
302 524
525 PERIODIC WATCHERS - to cron or not to cron?
303 $w = EV::periodic $at, $interval, $reschedule_cb, $callback 526 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
304 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 527 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
528 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
529 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
305 Similar to EV::timer, but is not based on relative timeouts but on 530 Similar to EV::timer, but is not based on relative timeouts but on
306 absolute times. Apart from creating "simple" timers that trigger 531 absolute times. Apart from creating "simple" timers that trigger
307 "at" the specified time, it can also be used for non-drifting 532 "at" the specified time, it can also be used for non-drifting
308 absolute timers and more complex, cron-like, setups that are not 533 absolute timers and more complex, cron-like, setups that are not
309 adversely affected by time jumps (i.e. when the system clock is 534 adversely affected by time jumps (i.e. when the system clock is
310 changed by explicit date -s or other means such as ntpd). It is also 535 changed by explicit date -s or other means such as ntpd). It is also
311 the most complex watcher type in EV. 536 the most complex watcher type in EV.
312 537
313 It has three distinct "modes": 538 It has three distinct "modes":
314 539
315 * absolute timer ($interval = $reschedule_cb = 0) 540 * absolute timer ($interval = $reschedule_cb = 0)
541
316 This time simply fires at the wallclock time $at and doesn't 542 This time simply fires at the wallclock time $at and doesn't
317 repeat. It will not adjust when a time jump occurs, that is, if 543 repeat. It will not adjust when a time jump occurs, that is, if
318 it is to be run at January 1st 2011 then it will run when the 544 it is to be run at January 1st 2011 then it will run when the
319 system time reaches or surpasses this time. 545 system time reaches or surpasses this time.
320 546
321 * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 547 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
548
322 In this mode the watcher will always be scheduled to time out at 549 In this mode the watcher will always be scheduled to time out at
323 the next "$at + N * $interval" time (for some integer N) and 550 the next "$at + N * $interval" time (for some integer N) and
324 then repeat, regardless of any time jumps. 551 then repeat, regardless of any time jumps.
325 552
326 This can be used to create timers that do not drift with respect 553 This can be used to create timers that do not drift with respect
… …
335 Another way to think about it (for the mathematically inclined) 562 Another way to think about it (for the mathematically inclined)
336 is that EV::periodic will try to run the callback in this mode 563 is that EV::periodic will try to run the callback in this mode
337 at the next possible time where "$time = $at (mod $interval)", 564 at the next possible time where "$time = $at (mod $interval)",
338 regardless of any time jumps. 565 regardless of any time jumps.
339 566
340 * manual reschedule mode ($reschedule_cb = coderef) 567 * manual reschedule mode ($reschedule_cb = coderef)
568
341 In this mode $interval and $at are both being ignored. Instead, 569 In this mode $interval and $at are both being ignored. Instead,
342 each time the periodic watcher gets scheduled, the reschedule 570 each time the periodic watcher gets scheduled, the reschedule
343 callback ($reschedule_cb) will be called with the watcher as 571 callback ($reschedule_cb) will be called with the watcher as
344 first, and the current time as second argument. 572 first, and the current time as second argument.
345 573
346 *This callback MUST NOT stop or destroy this or any other 574 *This callback MUST NOT stop or destroy this or any other
575 periodic watcher, ever, and MUST NOT call any event loop
347 periodic watcher, ever*. If you need to stop it, return 1e30 and 576 functions or methods*. If you need to stop it, return 1e30 and
348 stop it afterwards. 577 stop it afterwards. You may create and start a "EV::prepare"
578 watcher for this task.
349 579
350 It must return the next time to trigger, based on the passed 580 It must return the next time to trigger, based on the passed
351 time value (that is, the lowest time value larger than to the 581 time value (that is, the lowest time value larger than or equal
352 second argument). It will usually be called just before the 582 to to the second argument). It will usually be called just
353 callback will be triggered, but might be called at other times, 583 before the callback will be triggered, but might be called at
354 too. 584 other times, too.
355 585
356 This can be used to create very complex timers, such as a timer 586 This can be used to create very complex timers, such as a timer
357 that triggers on each midnight, local time (actually 24 hours 587 that triggers on each midnight, local time (actually 24 hours
358 after the last midnight, to keep the example simple. If you know 588 after the last midnight, to keep the example simple. If you know
359 a way to do it correctly in about the same space (without 589 a way to do it correctly in about the same space (without
… …
372 The "periodic_ns" variant doesn't start (activate) the newly created 602 The "periodic_ns" variant doesn't start (activate) the newly created
373 watcher. 603 watcher.
374 604
375 $w->set ($at, $interval, $reschedule_cb) 605 $w->set ($at, $interval, $reschedule_cb)
376 Reconfigures the watcher, see the constructor above for details. Can 606 Reconfigures the watcher, see the constructor above for details. Can
377 be at any time. 607 be called at any time.
378 608
379 $w->again 609 $w->again
380 Simply stops and starts the watcher again. 610 Simply stops and starts the watcher again.
381 611
612 $time = $w->at
613 Return the time that the watcher is expected to trigger next.
614
615 SIGNAL WATCHERS - signal me when a signal gets signalled!
382 $w = EV::signal $signal, $callback 616 $w = EV::signal $signal, $callback
383 $w = EV::signal_ns $signal, $callback 617 $w = EV::signal_ns $signal, $callback
618 $w = $loop->signal ($signal, $callback)
619 $w = $loop->signal_ns ($signal, $callback)
384 Call the callback when $signal is received (the signal can be 620 Call the callback when $signal is received (the signal can be
385 specified by number or by name, just as with kill or %SIG). 621 specified by number or by name, just as with "kill" or %SIG).
622
623 Only one event loop can grab a given signal - attempting to grab the
624 same signal from two EV loops will crash the program immediately or
625 cause data corruption.
386 626
387 EV will grab the signal for the process (the kernel only allows one 627 EV will grab the signal for the process (the kernel only allows one
388 component to receive a signal at a time) when you start a signal 628 component to receive a signal at a time) when you start a signal
389 watcher, and removes it again when you stop it. Perl does the same 629 watcher, and removes it again when you stop it. Perl does the same
390 when you add/remove callbacks to %SIG, so watch out. 630 when you add/remove callbacks to %SIG, so watch out.
… …
394 The "signal_ns" variant doesn't start (activate) the newly created 634 The "signal_ns" variant doesn't start (activate) the newly created
395 watcher. 635 watcher.
396 636
397 $w->set ($signal) 637 $w->set ($signal)
398 Reconfigures the watcher, see the constructor above for details. Can 638 Reconfigures the watcher, see the constructor above for details. Can
399 be at any time. 639 be called at any time.
400 640
401 $current_signum = $w->signal 641 $current_signum = $w->signal
402 $old_signum = $w->signal ($new_signal) 642 $old_signum = $w->signal ($new_signal)
403 Returns the previously set signal (always as a number not name) and 643 Returns the previously set signal (always as a number not name) and
404 optionally set a new one. 644 optionally set a new one.
405 645
646 CHILD WATCHERS - watch out for process status changes
406 $w = EV::child $pid, $callback 647 $w = EV::child $pid, $trace, $callback
407 $w = EV::child_ns $pid, $callback 648 $w = EV::child_ns $pid, $trace, $callback
649 $w = $loop->child ($pid, $trace, $callback)
650 $w = $loop->child_ns ($pid, $trace, $callback)
408 Call the callback when a status change for pid $pid (or any pid if 651 Call the callback when a status change for pid $pid (or any pid if
409 $pid is 0) has been received. More precisely: when the process 652 $pid is 0) has been received (a status change happens when the
653 process terminates or is killed, or, when trace is true,
654 additionally when it is stopped or continued). More precisely: when
410 receives a SIGCHLD, EV will fetch the outstanding exit/wait status 655 the process receives a "SIGCHLD", EV will fetch the outstanding
411 for all changed/zombie children and call the callback. 656 exit/wait status for all changed/zombie children and call the
657 callback.
412 658
413 You can access both status and pid by using the "rstatus" and "rpid" 659 It is valid (and fully supported) to install a child watcher after a
660 child has exited but before the event loop has started its next
661 iteration (for example, first you "fork", then the new child process
662 might exit, and only then do you install a child watcher in the
663 parent for the new pid).
664
665 You can access both exit (or tracing) status and pid by using the
414 methods on the watcher object. 666 "rstatus" and "rpid" methods on the watcher object.
415 667
416 You can have as many pid watchers per pid as you want. 668 You can have as many pid watchers per pid as you want, they will all
669 be called.
417 670
418 The "child_ns" variant doesn't start (activate) the newly created 671 The "child_ns" variant doesn't start (activate) the newly created
419 watcher. 672 watcher.
420 673
421 $w->set ($pid) 674 $w->set ($pid, $trace)
422 Reconfigures the watcher, see the constructor above for details. Can 675 Reconfigures the watcher, see the constructor above for details. Can
423 be at any time. 676 be called at any time.
424 677
425 $current_pid = $w->pid 678 $current_pid = $w->pid
426 $old_pid = $w->pid ($new_pid)
427 Returns the previously set process id and optionally set a new one. 679 Returns the previously set process id and optionally set a new one.
428 680
429 $exit_status = $w->rstatus 681 $exit_status = $w->rstatus
430 Return the exit/wait status (as returned by waitpid, see the waitpid 682 Return the exit/wait status (as returned by waitpid, see the waitpid
431 entry in perlfunc). 683 entry in perlfunc).
432 684
433 $pid = $w->rpid 685 $pid = $w->rpid
434 Return the pid of the awaited child (useful when you have installed 686 Return the pid of the awaited child (useful when you have installed
435 a watcher for all pids). 687 a watcher for all pids).
436 688
689 STAT WATCHERS - did the file attributes just change?
690 $w = EV::stat $path, $interval, $callback
691 $w = EV::stat_ns $path, $interval, $callback
692 $w = $loop->stat ($path, $interval, $callback)
693 $w = $loop->stat_ns ($path, $interval, $callback)
694 Call the callback when a file status change has been detected on
695 $path. The $path does not need to exist, changing from "path exists"
696 to "path does not exist" is a status change like any other.
697
698 The $interval is a recommended polling interval for systems where
699 OS-supported change notifications don't exist or are not supported.
700 If you use 0 then an unspecified default is used (which is highly
701 recommended!), which is to be expected to be around five seconds
702 usually.
703
704 This watcher type is not meant for massive numbers of stat watchers,
705 as even with OS-supported change notifications, this can be
706 resource-intensive.
707
708 The "stat_ns" variant doesn't start (activate) the newly created
709 watcher.
710
711 ... = $w->stat
712 This call is very similar to the perl "stat" built-in: It stats
713 (using "lstat") the path specified in the watcher and sets perls
714 stat cache (as well as EV's idea of the current stat values) to the
715 values found.
716
717 In scalar context, a boolean is return indicating success or failure
718 of the stat. In list context, the same 13-value list as with stat is
719 returned (except that the blksize and blocks fields are not
720 reliable).
721
722 In the case of an error, errno is set to "ENOENT" (regardless of the
723 actual error value) and the "nlink" value is forced to zero (if the
724 stat was successful then nlink is guaranteed to be non-zero).
725
726 See also the next two entries for more info.
727
728 ... = $w->attr
729 Just like "$w->stat", but without the initial stat'ing: this returns
730 the values most recently detected by EV. See the next entry for more
731 info.
732
733 ... = $w->prev
734 Just like "$w->stat", but without the initial stat'ing: this returns
735 the previous set of values, before the change.
736
737 That is, when the watcher callback is invoked, "$w->prev" will be
738 set to the values found *before* a change was detected, while
739 "$w->attr" returns the values found leading to the change detection.
740 The difference (if any) between "prev" and "attr" is what triggered
741 the callback.
742
743 If you did something to the filesystem object and do not want to
744 trigger yet another change, you can call "stat" to update EV's idea
745 of what the current attributes are.
746
747 $w->set ($path, $interval)
748 Reconfigures the watcher, see the constructor above for details. Can
749 be called at any time.
750
751 $current_path = $w->path
752 $old_path = $w->path ($new_path)
753 Returns the previously set path and optionally set a new one.
754
755 $current_interval = $w->interval
756 $old_interval = $w->interval ($new_interval)
757 Returns the previously set interval and optionally set a new one.
758 Can be used to query the actual interval used.
759
760 IDLE WATCHERS - when you've got nothing better to do...
437 $w = EV::idle $callback 761 $w = EV::idle $callback
438 $w = EV::idle_ns $callback 762 $w = EV::idle_ns $callback
763 $w = $loop->idle ($callback)
764 $w = $loop->idle_ns ($callback)
439 Call the callback when there are no pending io, timer/periodic, 765 Call the callback when there are no other pending watchers of the
440 signal or child events, i.e. when the process is idle. 766 same or higher priority (excluding check, prepare and other idle
767 watchers of the same or lower priority, of course). They are called
768 idle watchers because when the watcher is the highest priority
769 pending event in the process, the process is considered to be idle
770 at that priority.
771
772 If you want a watcher that is only ever called when *no* other
773 events are outstanding you have to set the priority to "EV::MINPRI".
441 774
442 The process will not block as long as any idle watchers are active, 775 The process will not block as long as any idle watchers are active,
443 and they will be called repeatedly until stopped. 776 and they will be called repeatedly until stopped.
444 777
778 For example, if you have idle watchers at priority 0 and 1, and an
779 I/O watcher at priority 0, then the idle watcher at priority 1 and
780 the I/O watcher will always run when ready. Only when the idle
781 watcher at priority 1 is stopped and the I/O watcher at priority 0
782 is not pending with the 0-priority idle watcher be invoked.
783
445 The "idle_ns" variant doesn't start (activate) the newly created 784 The "idle_ns" variant doesn't start (activate) the newly created
446 watcher. 785 watcher.
447 786
787 PREPARE WATCHERS - customise your event loop!
448 $w = EV::prepare $callback 788 $w = EV::prepare $callback
449 $w = EV::prepare_ns $callback 789 $w = EV::prepare_ns $callback
790 $w = $loop->prepare ($callback)
791 $w = $loop->prepare_ns ($callback)
450 Call the callback just before the process would block. You can still 792 Call the callback just before the process would block. You can still
451 create/modify any watchers at this point. 793 create/modify any watchers at this point.
452 794
453 See the EV::check watcher, below, for explanations and an example. 795 See the EV::check watcher, below, for explanations and an example.
454 796
455 The "prepare_ns" variant doesn't start (activate) the newly created 797 The "prepare_ns" variant doesn't start (activate) the newly created
456 watcher. 798 watcher.
457 799
800 CHECK WATCHERS - customise your event loop even more!
458 $w = EV::check $callback 801 $w = EV::check $callback
459 $w = EV::check_ns $callback 802 $w = EV::check_ns $callback
803 $w = $loop->check ($callback)
804 $w = $loop->check_ns ($callback)
460 Call the callback just after the process wakes up again (after it 805 Call the callback just after the process wakes up again (after it
461 has gathered events), but before any other callbacks have been 806 has gathered events), but before any other callbacks have been
462 invoked. 807 invoked.
463 808
464 This is used to integrate other event-based software into the EV 809 This can be used to integrate other event-based software into the EV
465 mainloop: You register a prepare callback and in there, you create 810 mainloop: You register a prepare callback and in there, you create
466 io and timer watchers as required by the other software. Here is a 811 io and timer watchers as required by the other software. Here is a
467 real-world example of integrating Net::SNMP (with some details left 812 real-world example of integrating Net::SNMP (with some details left
468 out): 813 out):
469 814
… …
475 or return; 820 or return;
476 821
477 # make the dispatcher handle any outstanding stuff 822 # make the dispatcher handle any outstanding stuff
478 ... not shown 823 ... not shown
479 824
480 # create an IO watcher for each and every socket 825 # create an I/O watcher for each and every socket
481 @snmp_watcher = ( 826 @snmp_watcher = (
482 (map { EV::io $_, EV::READ, sub { } } 827 (map { EV::io $_, EV::READ, sub { } }
483 keys %{ $dispatcher->{_descriptors} }), 828 keys %{ $dispatcher->{_descriptors} }),
484 829
485 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 830 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
… …
500 # make the dispatcher handle any new stuff 845 # make the dispatcher handle any new stuff
501 ... not shown 846 ... not shown
502 }; 847 };
503 848
504 The callbacks of the created watchers will not be called as the 849 The callbacks of the created watchers will not be called as the
505 watchers are destroyed before this cna happen (remember EV::check 850 watchers are destroyed before this can happen (remember EV::check
506 gets called first). 851 gets called first).
507 852
508 The "check_ns" variant doesn't start (activate) the newly created 853 The "check_ns" variant doesn't start (activate) the newly created
509 watcher. 854 watcher.
510 855
856 EV::CHECK constant issues
857 Like all other watcher types, there is a bitmask constant for use in
858 $revents and other places. The "EV::CHECK" is special as it has the
859 same name as the "CHECK" sub called by Perl. This doesn't cause big
860 issues on newer perls (beginning with 5.8.9), but it means thatthe
861 constant must be *inlined*, i.e. runtime calls will not work. That
862 means that as long as you always "use EV" and then "EV::CHECK" you
863 are on the safe side.
864
865 FORK WATCHERS - the audacity to resume the event loop after a fork
866 Fork watchers are called when a "fork ()" was detected. The invocation
867 is done before the event loop blocks next and before "check" watchers
868 are being called, and only in the child after the fork.
869
870 $w = EV::fork $callback
871 $w = EV::fork_ns $callback
872 $w = $loop->fork ($callback)
873 $w = $loop->fork_ns ($callback)
874 Call the callback before the event loop is resumed in the child
875 process after a fork.
876
877 The "fork_ns" variant doesn't start (activate) the newly created
878 watcher.
879
880 EMBED WATCHERS - when one backend isn't enough...
881 This is a rather advanced watcher type that lets you embed one event
882 loop into another (currently only IO events are supported in the
883 embedded loop, other types of watchers might be handled in a delayed or
884 incorrect fashion and must not be used).
885
886 See the libev documentation at
887 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code
888 _when_one_backend_> (locally installed as EV::libev) for more details.
889
890 In short, this watcher is most useful on BSD systems without working
891 kqueue to still be able to handle a large number of sockets:
892
893 my $socket_loop;
894
895 # check wether we use SELECT or POLL _and_ KQUEUE is supported
896 if (
897 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
898 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
899 ) {
900 # use kqueue for sockets
901 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
902 }
903
904 # use the default loop otherwise
905 $socket_loop ||= EV::default_loop;
906
907 $w = EV::embed $otherloop[, $callback]
908 $w = EV::embed_ns $otherloop[, $callback]
909 $w = $loop->embed ($otherloop[, $callback])
910 $w = $loop->embed_ns ($otherloop[, $callback])
911 Call the callback when the embedded event loop ($otherloop) has any
912 I/O activity. The $callback is optional: if it is missing, then the
913 embedded event loop will be managed automatically (which is
914 recommended), otherwise you have to invoke "sweep" yourself.
915
916 The "embed_ns" variant doesn't start (activate) the newly created
917 watcher.
918
919 ASYNC WATCHERS - how to wake up another event loop
920 Async watchers are provided by EV, but have little use in perl directly,
921 as perl neither supports threads running in parallel nor direct access
922 to signal handlers or other contexts where they could be of value.
923
924 It is, however, possible to use them from the XS level.
925
926 Please see the libev documentation for further details.
927
928 $w = EV::async $callback
929 $w = EV::async_ns $callback
930 $w->send
931 $bool = $w->async_pending
932
933PERL SIGNALS
934 While Perl signal handling (%SIG) is not affected by EV, the behaviour
935 with EV is as the same as any other C library: Perl-signals will only be
936 handled when Perl runs, which means your signal handler might be invoked
937 only the next time an event callback is invoked.
938
939 The solution is to use EV signal watchers (see "EV::signal"), which will
940 ensure proper operations with regards to other event watchers.
941
942 If you cannot do this for whatever reason, you can also force a watcher
943 to be called on every event loop iteration by installing a "EV::check"
944 watcher:
945
946 my $async_check = EV::check sub { };
947
948 This ensures that perl gets into control for a short time to handle any
949 pending signals, and also ensures (slightly) slower overall operation.
950
511THREADS 951ITHREADS
512 Threads are not supported by this module in any way. Perl pseudo-threads 952 Ithreads are not supported by this module in any way. Perl
513 is evil stuff and must die. As soon as Perl gains real threads I will 953 pseudo-threads is evil stuff and must die. Real threads as provided by
514 work on thread support for it. 954 Coro are fully supported (and enhanced support is available via
955 Coro::EV).
515 956
516FORK 957FORK
517 Most of the "improved" event delivering mechanisms of modern operating 958 Most of the "improved" event delivering mechanisms of modern operating
518 systems have quite a few problems with fork(2) (to put it bluntly: it is 959 systems have quite a few problems with fork(2) (to put it bluntly: it is
519 not supported and usually destructive). Libev makes it possible to work 960 not supported and usually destructive). Libev makes it possible to work
… …
529 970
530 On win32, there is no notion of fork so all this doesn't apply, of 971 On win32, there is no notion of fork so all this doesn't apply, of
531 course. 972 course.
532 973
533SEE ALSO 974SEE ALSO
534 L<EV::DNS>. 975 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
976 DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed
977 Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV
978 (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event
979 driven programming.
535 980
536AUTHOR 981AUTHOR
537 Marc Lehmann <schmorp@schmorp.de> 982 Marc Lehmann <schmorp@schmorp.de>
538 http://home.schmorp.de/ 983 http://home.schmorp.de/
539 984

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