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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 { 44 # STAT CHANGES
11 warn "is called after 2s"; 45 my $w = EV::stat "/etc/passwd", 10, sub {
46 my ($w, $revents) = @_;
47 warn $w->path, " has changed somehow.\n";
12 }; 48 };
13 49
14 my $w = EV::timer 2, 1, sub {
15 warn "is called roughly every 2s (repeat = 1)";
16 };
17
18 undef $w; # destroy event watcher again
19
20 my $w = EV::periodic 0, 60, sub {
21 warn "is called every minute, on the minute, exactly";
22 };
23
24 # IO
25
26 my $w = EV::io *STDIN, EV::READ, sub {
27 my ($w, $revents) = @_; # all callbacks get the watcher object and event mask
28 warn "stdin is readable, you entered: ", <STDIN>;
29 };
30
31 # SIGNALS
32
33 my $w = EV::signal 'QUIT', sub {
34 warn "sigquit received\n";
35 };
36
37 my $w = EV::signal 3, sub {
38 warn "sigquit received (this is GNU/Linux, right?)\n";
39 };
40
41 # CHILD/PID STATUS CHANGES
42
43 my $w = EV::child 666, sub {
44 my ($w, $revents, $status) = @_;
45 };
46
47 # MAINLOOP 50 # MAINLOOP
48 EV::loop; # loop until EV::loop_done is called 51 EV::run; # loop until EV::unloop is called or all watchers stop
49 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
50 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.
51 63
52DESCRIPTION 64DESCRIPTION
53 This module provides an interface to libev 65 This module provides an interface to libev
54 (<http://software.schmorp.de/pkg/libev.html>). 66 (<http://software.schmorp.de/pkg/libev.html>). While the documentation
67 below is comprehensive, one might also consult the documentation of
68 libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
69 perldoc EV::libev) for more subtle details on watcher semantics or some
70 discussion on the available backends, or how to force a specific backend
71 with "LIBEV_FLAGS", or just about in any case because it has much more
72 detailed information.
73
74 This module is very fast and scalable. It is actually so fast that you
75 can use it through the AnyEvent module, stay portable to other event
76 loops (if you don't rely on any watcher types not available through it)
77 and still be faster than with any other event loop currently supported
78 in Perl.
79
80 PORTING FROM EV 3.X to 4.X
81 EV version 4 introduces a number of incompatible changes summarised
82 here. According to the depreciation strategy used by libev, there is a
83 compatibility layer in place so programs should continue to run
84 unchanged (the XS interface lacks this layer, so programs using that one
85 need to be updated).
86
87 This compatibility layer will be switched off in some future release.
88
89 All changes relevant to Perl are renames of symbols, functions and
90 methods:
91
92 EV::loop => EV::run
93 EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
94 EV::LOOP_ONESHOT => EV::RUN_ONCE
95
96 EV::unloop => EV::break
97 EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
98 EV::UNLOOP_ONE => EV::BREAK_ONE
99 EV::UNLOOP_ALL => EV::BREAK_ALL
100
101 EV::TIMEOUT => EV::TIMER
102
103 EV::loop_count => EV::iteration
104 EV::loop_depth => EV::depth
105 EV::loop_verify => EV::verify
106
107 The loop object methods corresponding to the functions above have been
108 similarly renamed.
109
110 MODULE EXPORTS
111 This module does not export any symbols.
112
113EVENT LOOPS
114 EV supports multiple event loops: There is a single "default event loop"
115 that can handle everything including signals and child watchers, and any
116 number of "dynamic event loops" that can use different backends (with
117 various limitations), but no child and signal watchers.
118
119 You do not have to do anything to create the default event loop: When
120 the module is loaded a suitable backend is selected on the premise of
121 selecting a working backend (which for example rules out kqueue on most
122 BSDs). Modules should, unless they have "special needs" always use the
123 default loop as this is fastest (perl-wise), best supported by other
124 modules (e.g. AnyEvent or Coro) and most portable event loop.
125
126 For specific programs you can create additional event loops dynamically.
127
128 If you want to take advantage of kqueue (which often works properly for
129 sockets only) even though the default loop doesn't enable it, you can
130 *embed* a kqueue loop into the default loop: running the default loop
131 will then also service the kqueue loop to some extent. See the example
132 in the section about embed watchers for an example on how to achieve
133 that.
134
135 $loop = new EV::Loop [$flags]
136 Create a new event loop as per the specified flags. Please refer to
137 the "ev_loop_new ()" function description in the libev documentation
138 (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
139 ONS>, or locally-installed as EV::libev manpage) for more info.
140
141 The loop will automatically be destroyed when it is no longer
142 referenced by any watcher and the loop object goes out of scope.
143
144 If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK"
145 is recommended, as only the default event loop is protected by this
146 module. If you *are* embedding this loop in the default loop, this
147 is not necessary, as "EV::embed" automatically does the right thing
148 on fork.
149
150 $loop->loop_fork
151 Must be called after a fork in the child, before entering or
152 continuing the event loop. An alternative is to use
153 "EV::FLAG_FORKCHECK" which calls this function automatically, at
154 some performance loss (refer to the libev documentation).
155
156 $loop->verify
157 Calls "ev_verify" to make internal consistency checks (for debugging
158 libev) and abort the program if any data structures were found to be
159 corrupted.
160
161 $loop = EV::default_loop [$flags]
162 Return the default loop (which is a singleton object). Since this
163 module already creates the default loop with default flags,
164 specifying flags here will not have any effect unless you destroy
165 the default loop first, which isn't supported. So in short: don't do
166 it, and if you break it, you get to keep the pieces.
55 167
56BASIC INTERFACE 168BASIC INTERFACE
57 $EV::DIED 169 $EV::DIED
58 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
59 callback throws an exception (with $@ containing thr error). The 171 callback throws an exception (with $@ containing the error). The
60 default prints an informative message and continues. 172 default prints an informative message and continues.
61 173
62 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.
63 186
64 $time = EV::time 187 $time = EV::time
65 Returns the current time in (fractional) seconds since the epoch. 188 Returns the current time in (fractional) seconds since the epoch.
66 189
67 $time = EV::now 190 $time = EV::now
191 $time = $loop->now
68 Returns the time the last event loop iteration has been started. 192 Returns the time the last event loop iteration has been started.
69 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
70 to it is usually faster then calling EV::time. 194 to it is usually faster then calling EV::time.
71 195
72 $method = EV::ev_method 196 EV::now_update
197 $loop->now_update
198 Establishes the current time by querying the kernel, updating the
199 time returned by "EV::now" in the progress. This is a costly
200 operation and is usually done automatically within "EV::loop".
201
202 This function is rarely useful, but when some event callback runs
203 for a very long time without entering the event loop, updating
204 libev's idea of the current time is a good idea.
205
206 EV::suspend
207 $loop->suspend
208 EV::resume
209 $loop->resume
210 These two functions suspend and resume a loop, for use when the loop
211 is not used for a while and timeouts should not be processed.
212
213 A typical use case would be an interactive program such as a game:
214 When the user presses "^Z" to suspend the game and resumes it an
215 hour later it would be best to handle timeouts as if no time had
216 actually passed while the program was suspended. This can be
217 achieved by calling "suspend" in your "SIGTSTP" handler, sending
218 yourself a "SIGSTOP" and calling "resume" directly afterwards to
219 resume timer processing.
220
221 Effectively, all "timer" watchers will be delayed by the time spend
222 between "suspend" and "resume", and all "periodic" watchers will be
223 rescheduled (that is, they will lose any events that would have
224 occured while suspended).
225
226 After calling "suspend" you must not call *any* function on the
227 given loop other than "resume", and you must not call "resume"
228 without a previous call to "suspend".
229
230 Calling "suspend"/"resume" has the side effect of updating the event
231 loop time (see "now_update").
232
233 $backend = EV::backend
234 $backend = $loop->backend
73 Returns an integer describing the backend used by libev 235 Returns an integer describing the backend used by libev
74 (EV::METHOD_SELECT or EV::METHOD_EPOLL). 236 (EV::BACKEND_SELECT or EV::BACKEND_EPOLL).
75 237
76 EV::loop [$flags] 238 $active = EV::run [$flags]
239 $active = $loop->run ([$flags])
77 Begin checking for events and calling callbacks. It returns when a 240 Begin checking for events and calling callbacks. It returns when a
78 callback calls EV::loop_done. 241 callback calls EV::unloop or the flasg are nonzero (in which case
242 the 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".
79 246
80 The $flags argument can be one of the following: 247 The $flags argument can be one of the following:
81 248
82 0 as above 249 0 as above
83 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 250 EV::RUN_ONCE block at most once (wait, but do not loop)
84 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 251 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
85 252
86 EV::loop_done [$how] 253 EV::break [$how]
254 $loop->break ([$how])
87 When called with no arguments or an argument of 1, makes the 255 When called with no arguments or an argument of EV::BREAK_ONE, makes
88 innermost call to EV::loop return. 256 the innermost call to EV::loop return.
89 257
90 When called with an agrument of 2, all calls to EV::loop will return 258 When called with an argument of EV::BREAK_ALL, all calls to EV::loop
91 as fast as possible. 259 will return as fast as possible.
92 260
93 WATCHER 261 When called with an argument of EV::BREAK_CANCEL, any pending break
262 will be cancelled.
263
264 $count = EV::iteration
265 $count = $loop->iteration
266 Return the number of times the event loop has polled for new events.
267 Sometimes useful as a generation counter.
268
269 EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
270 $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
271 This function rolls together an I/O and a timer watcher for a single
272 one-shot event without the need for managing a watcher object.
273
274 If $fh_or_undef is a filehandle or file descriptor, then $events
275 must be a bitset containing either "EV::READ", "EV::WRITE" or
276 "EV::READ | EV::WRITE", indicating the type of I/O event you want to
277 wait for. If you do not want to wait for some I/O event, specify
278 "undef" for $fh_or_undef and 0 for $events).
279
280 If timeout is "undef" or negative, then there will be no timeout.
281 Otherwise a EV::timer with this value will be started.
282
283 When an error occurs or either the timeout or I/O watcher triggers,
284 then the callback will be called with the received event set (in
285 general you can expect it to be a combination of "EV::ERROR",
286 "EV::READ", "EV::WRITE" and "EV::TIMER").
287
288 EV::once doesn't return anything: the watchers stay active till
289 either of them triggers, then they will be stopped and freed, and
290 the callback invoked.
291
292 EV::feed_fd_event $fd, $revents
293 $loop->feed_fd_event ($fd, $revents)
294 Feed an event on a file descriptor into EV. EV will react to this
295 call as if the readyness notifications specified by $revents (a
296 combination of "EV::READ" and "EV::WRITE") happened on the file
297 descriptor $fd.
298
299 EV::feed_signal_event $signal
300 Feed a signal event into the default loop. EV will react to this
301 call as if the signal specified by $signal had occured.
302
303 EV::feed_signal $signal
304 Feed a signal event into EV - unlike "EV::feed_signal_event", this
305 works regardless of which loop has registered the signal, and is
306 mainly useful fro custom signal implementations.
307
308 EV::set_io_collect_interval $time
309 $loop->set_io_collect_interval ($time)
310 EV::set_timeout_collect_interval $time
311 $loop->set_timeout_collect_interval ($time)
312 These advanced functions set the minimum block interval when polling
313 for I/O events and the minimum wait interval for timer events. See
314 the libev documentation at
315 <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT
316 ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more
317 detailed discussion.
318
319 $count = EV::pending_count
320 $count = $loop->pending_count
321 Returns the number of currently pending watchers.
322
323 EV::invoke_pending
324 $loop->invoke_pending
325 Invoke all currently pending watchers.
326
327WATCHER OBJECTS
94 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
95 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,
96 you would create an EV::io watcher for that: 330 you would create an EV::io watcher for that:
97 331
98 my $watcher = EV::io *STDIN, EV::READ, sub { 332 my $watcher = EV::io *STDIN, EV::READ, sub {
99 my ($watcher, $revents) = @_; 333 my ($watcher, $revents) = @_;
100 warn "yeah, STDIN should not be readable without blocking!\n" 334 warn "yeah, STDIN should now be readable without blocking!\n"
101 }; 335 };
102 336
103 All watchers can be active (waiting for events) or inactive (paused). 337 All watchers can be active (waiting for events) or inactive (paused).
104 Only active watchers will have their callbacks invoked. All callbacks 338 Only active watchers will have their callbacks invoked. All callbacks
105 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
106 received events. 340 received events.
107 341
108 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
109 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
110 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,
111 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
112 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).
113 (which uses EV::TIMEOUT).
114 347
115 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
116 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
117 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.
118 351
119 Please note that a watcher will automatically be stopped when the 352 Please note that a watcher will automatically be stopped when the
120 watcher object is returned, so you *need* to keep the watcher objects 353 watcher object is destroyed, so you *need* to keep the watcher objects
121 returned by the constructors. 354 returned by the constructors.
122 355
123 WATCHER TYPES 356 Also, all methods changing some aspect of a watcher (->set, ->priority,
124 Now lets move to the existing watcher types and asociated methods. 357 ->fh and so on) automatically stop and start it again if it is active,
358 which means pending events get lost.
125 359
126 The following methods are available for all watchers. Then followes a 360 COMMON WATCHER METHODS
127 description of each watcher constructor (EV::io, EV::timer, 361 This section lists methods common to all watchers.
128 EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and
129 EV::check), followed by any type-specific methods (if any).
130 362
131 $w->start 363 $w->start
132 Starts a watcher if it isn't active already. Does nothing to an 364 Starts a watcher if it isn't active already. Does nothing to an
133 already active watcher. By default, all watchers start out in the 365 already active watcher. By default, all watchers start out in the
134 active state (see the description of the "_ns" variants if you need 366 active state (see the description of the "_ns" variants if you need
135 stopped watchers). 367 stopped watchers).
136 368
137 $w->stop 369 $w->stop
138 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
139 (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
140 callback invocation), regardless of wether the watcher was active or 372 callback invocation), regardless of whether the watcher was active
141 not. 373 or not.
142 374
143 $bool = $w->is_active 375 $bool = $w->is_active
144 Returns true if the watcher is active, false otherwise. 376 Returns true if the watcher is active, false otherwise.
377
378 $current_data = $w->data
379 $old_data = $w->data ($new_data)
380 Queries a freely usable data scalar on the watcher and optionally
381 changes it. This is a way to associate custom data with a watcher:
382
383 my $w = EV::timer 60, 0, sub {
384 warn $_[0]->data;
385 };
386 $w->data ("print me!");
145 387
146 $current_cb = $w->cb 388 $current_cb = $w->cb
147 $old_cb = $w->cb ($new_cb) 389 $old_cb = $w->cb ($new_cb)
148 Queries the callback on the watcher and optionally changes it. You 390 Queries the callback on the watcher and optionally changes it. You
149 cna do this at any time. 391 can do this at any time without the watcher restarting.
150 392
393 $current_priority = $w->priority
394 $old_priority = $w->priority ($new_priority)
395 Queries the priority on the watcher and optionally changes it.
396 Pending watchers with higher priority will be invoked first. The
397 valid range of priorities lies between EV::MAXPRI (default 2) and
398 EV::MINPRI (default -2). If the priority is outside this range it
399 will automatically be normalised to the nearest valid priority.
400
401 The default priority of any newly-created watcher is 0.
402
403 Note that the priority semantics have not yet been fleshed out and
404 are subject to almost certain change.
405
151 $w->trigger ($revents) 406 $w->invoke ($revents)
152 Call the callback *now* with the given event mask. 407 Call the callback *now* with the given event mask.
153 408
409 $w->feed_event ($revents)
410 Feed some events on this watcher into EV. EV will react to this call
411 as if the watcher had received the given $revents mask.
412
413 $revents = $w->clear_pending
414 If the watcher is pending, this function clears its pending status
415 and returns its $revents bitset (as if its callback was invoked). If
416 the watcher isn't pending it does nothing and returns 0.
417
418 $previous_state = $w->keepalive ($bool)
419 Normally, "EV::loop" will return when there are no active watchers
420 (which is a "deadlock" because no progress can be made anymore).
421 This is convenient because it allows you to start your watchers (and
422 your jobs), call "EV::loop" once and when it returns you know that
423 all your jobs are finished (or they forgot to register some watchers
424 for their task :).
425
426 Sometimes, however, this gets in your way, for example when the
427 module that calls "EV::loop" (usually the main program) is not the
428 same module as a long-living watcher (for example a DNS client
429 module written by somebody else even). Then you might want any
430 outstanding requests to be handled, but you would not want to keep
431 "EV::loop" from returning just because you happen to have this
432 long-running UDP port watcher.
433
434 In this case you can clear the keepalive status, which means that
435 even though your watcher is active, it won't keep "EV::loop" from
436 returning.
437
438 The initial value for keepalive is true (enabled), and you can
439 change it any time.
440
441 Example: Register an I/O watcher for some UDP socket but do not keep
442 the event loop from running just because of that watcher.
443
444 my $udp_socket = ...
445 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
446 $udp_watcher->keepalive (0);
447
448 $loop = $w->loop
449 Return the loop that this watcher is attached to.
450
451WATCHER TYPES
452 Each of the following subsections describes a single watcher type.
453
454 I/O WATCHERS - is this file descriptor readable or writable?
154 $w = EV::io $fileno_or_fh, $eventmask, $callback 455 $w = EV::io $fileno_or_fh, $eventmask, $callback
155 $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)
156 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
157 when the events specified in $eventmask. 460 when at least one of events specified in $eventmask occurs.
158 461
159 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:
160 463
161 EV::READ wait until read() wouldn't block anymore 464 EV::READ wait until read() wouldn't block anymore
162 EV::WRITE wait until write() wouldn't block anymore 465 EV::WRITE wait until write() wouldn't block anymore
… …
174 477
175 $current_eventmask = $w->events 478 $current_eventmask = $w->events
176 $old_eventmask = $w->events ($new_eventmask) 479 $old_eventmask = $w->events ($new_eventmask)
177 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.
178 481
482 TIMER WATCHERS - relative and optionally repeating timeouts
179 $w = EV::timer $after, $repeat, $callback 483 $w = EV::timer $after, $repeat, $callback
180 $w = EV::timer_ns $after, $repeat, $callback 484 $w = EV::timer_ns $after, $repeat, $callback
181 Calls the callback after $after seconds. If $repeat is non-zero, the 485 $w = $loop->timer ($after, $repeat, $callback)
182 timer will be restarted (with the $repeat value as $after) after the 486 $w = $loop->timer_ns ($after, $repeat, $callback)
183 callback returns. 487 Calls the callback after $after seconds (which may be fractional).
488 If $repeat is non-zero, the timer will be restarted (with the
489 $repeat value as $after) after the callback returns.
184 490
185 This means that the callback would be called roughly after $after 491 This means that the callback would be called roughly after $after
186 seconds, and then every $repeat seconds. "Roughly" because the time 492 seconds, and then every $repeat seconds. The timer does his best not
187 of callback processing is not taken into account, so the timer will 493 to drift, but it will not invoke the timer more often then once per
188 slowly drift. If that isn't acceptable, look at EV::periodic. 494 event loop iteration, and might drift in other cases. If that isn't
495 acceptable, look at EV::periodic, which can provide long-term stable
496 timers.
189 497
190 The timer is based on a monotonic clock, that is if somebody is 498 The timer is based on a monotonic clock, that is, if somebody is
191 sitting in front of the machine while the timer is running and 499 sitting in front of the machine while the timer is running and
192 changes the system clock, the timer will nevertheless run (roughly) 500 changes the system clock, the timer will nevertheless run (roughly)
193 the same time. 501 the same time.
194 502
195 The "timer_ns" variant doesn't start (activate) the newly created 503 The "timer_ns" variant doesn't start (activate) the newly created
196 watcher. 504 watcher.
197 505
198 $w->set ($after, $repeat) 506 $w->set ($after, $repeat)
199 Reconfigures the watcher, see the constructor above for details. Can 507 Reconfigures the watcher, see the constructor above for details. Can
200 be at any time. 508 be called at any time.
201 509
202 $w->again 510 $w->again
203 Similar to the "start" method, but has special semantics for 511 Similar to the "start" method, but has special semantics for
204 repeating timers: 512 repeating timers:
205 513
514 If the timer is active and non-repeating, it will be stopped.
515
206 If the timer is active and repeating, reset the timeout to occur 516 If the timer is active and repeating, reset the timeout to occur
207 $repeat seconds after now. 517 $repeat seconds after now.
208 518
209 If the timer is active and non-repeating, it will be stopped.
210
211 If the timer is in active and repeating, start it. 519 If the timer is inactive and repeating, start it using the repeat
520 value.
212 521
213 Otherwise do nothing. 522 Otherwise do nothing.
214 523
215 This behaviour is useful when you have a timeout for some IO 524 This behaviour is useful when you have a timeout for some IO
216 operation. You create a timer object with the same value for $after 525 operation. You create a timer object with the same value for $after
217 and $repeat, and then, in the read/write watcher, run the "again" 526 and $repeat, and then, in the read/write watcher, run the "again"
218 method on the timeout. 527 method on the timeout.
219 528
529 PERIODIC WATCHERS - to cron or not to cron?
220 $w = EV::periodic $at, $interval, $callback 530 $w = EV::periodic $at, $interval, $reschedule_cb, $callback
221 $w = EV::periodic_ns $at, $interval, $callback 531 $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
222 Similar to EV::timer, but the time is given as an absolute point in 532 $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
223 time ($at), plus an optional $interval. 533 $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
534 Similar to EV::timer, but is not based on relative timeouts but on
535 absolute times. Apart from creating "simple" timers that trigger
536 "at" the specified time, it can also be used for non-drifting
537 absolute timers and more complex, cron-like, setups that are not
538 adversely affected by time jumps (i.e. when the system clock is
539 changed by explicit date -s or other means such as ntpd). It is also
540 the most complex watcher type in EV.
224 541
225 If the $interval is zero, then the callback will be called at the 542 It has three distinct "modes":
226 time $at if that is in the future, or as soon as possible if it is
227 in the past. It will not automatically repeat.
228 543
229 If the $interval is nonzero, then the watcher will always be 544 * absolute timer ($interval = $reschedule_cb = 0)
230 scheduled to time out at the next "$at + N * $interval" time.
231 545
232 This can be used to schedule a callback to run at very regular 546 This time simply fires at the wallclock time $at and doesn't
233 intervals, as long as the processing time is less then the interval 547 repeat. It will not adjust when a time jump occurs, that is, if
234 (otherwise obviously events will be skipped). 548 it is to be run at January 1st 2011 then it will run when the
549 system time reaches or surpasses this time.
235 550
551 * repeating interval timer ($interval > 0, $reschedule_cb = 0)
552
553 In this mode the watcher will always be scheduled to time out at
554 the next "$at + N * $interval" time (for some integer N) and
555 then repeat, regardless of any time jumps.
556
557 This can be used to create timers that do not drift with respect
558 to system time:
559
560 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
561
562 That doesn't mean there will always be 3600 seconds in between
563 triggers, but only that the the clalback will be called when the
564 system time shows a full hour (UTC).
565
236 Another way to think about it (for the mathematically inclined) is 566 Another way to think about it (for the mathematically inclined)
237 that EV::periodic will try to run the callback at the next possible 567 is that EV::periodic will try to run the callback in this mode
238 time where "$time = $at (mod $interval)", regardless of any time 568 at the next possible time where "$time = $at (mod $interval)",
239 jumps. 569 regardless of any time jumps.
240 570
241 This periodic timer is based on "wallclock time", that is, if the 571 * manual reschedule mode ($reschedule_cb = coderef)
242 clock changes ("ntp", "date -s" etc.), then the timer will 572
243 nevertheless run at the specified time. This means it will never 573 In this mode $interval and $at are both being ignored. Instead,
244 drift (it might jitter, but it will not drift). 574 each time the periodic watcher gets scheduled, the reschedule
575 callback ($reschedule_cb) will be called with the watcher as
576 first, and the current time as second argument.
577
578 *This callback MUST NOT stop or destroy this or any other
579 periodic watcher, ever, and MUST NOT call any event loop
580 functions or methods*. If you need to stop it, return 1e30 and
581 stop it afterwards. You may create and start a "EV::prepare"
582 watcher for this task.
583
584 It must return the next time to trigger, based on the passed
585 time value (that is, the lowest time value larger than or equal
586 to to the second argument). It will usually be called just
587 before the callback will be triggered, but might be called at
588 other times, too.
589
590 This can be used to create very complex timers, such as a timer
591 that triggers on each midnight, local time (actually 24 hours
592 after the last midnight, to keep the example simple. If you know
593 a way to do it correctly in about the same space (without
594 requiring elaborate modules), drop me a note :):
595
596 my $daily = EV::periodic 0, 0, sub {
597 my ($w, $now) = @_;
598
599 use Time::Local ();
600 my (undef, undef, undef, $d, $m, $y) = localtime $now;
601 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
602 }, sub {
603 print "it's midnight or likely shortly after, now\n";
604 };
245 605
246 The "periodic_ns" variant doesn't start (activate) the newly created 606 The "periodic_ns" variant doesn't start (activate) the newly created
247 watcher. 607 watcher.
248 608
249 $w->set ($at, $interval) 609 $w->set ($at, $interval, $reschedule_cb)
250 Reconfigures the watcher, see the constructor above for details. Can 610 Reconfigures the watcher, see the constructor above for details. Can
251 be at any time. 611 be called at any time.
252 612
613 $w->again
614 Simply stops and starts the watcher again.
615
616 $time = $w->at
617 Return the time that the watcher is expected to trigger next.
618
619 SIGNAL WATCHERS - signal me when a signal gets signalled!
253 $w = EV::signal $signal, $callback 620 $w = EV::signal $signal, $callback
254 $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)
255 Call the callback when $signal is received (the signal can be 624 Call the callback when $signal is received (the signal can be
256 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.
257 630
258 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
259 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
260 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
261 when you add/remove callbacks to %SIG, so watch out. 634 when you add/remove callbacks to %SIG, so watch out.
… …
265 The "signal_ns" variant doesn't start (activate) the newly created 638 The "signal_ns" variant doesn't start (activate) the newly created
266 watcher. 639 watcher.
267 640
268 $w->set ($signal) 641 $w->set ($signal)
269 Reconfigures the watcher, see the constructor above for details. Can 642 Reconfigures the watcher, see the constructor above for details. Can
270 be at any time. 643 be called at any time.
271 644
645 $current_signum = $w->signal
646 $old_signum = $w->signal ($new_signal)
647 Returns the previously set signal (always as a number not name) and
648 optionally set a new one.
649
650 CHILD WATCHERS - watch out for process status changes
272 $w = EV::child $pid, $callback 651 $w = EV::child $pid, $trace, $callback
273 $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)
274 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
275 $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
276 receives a SIGCHLD, EV will fetch the outstanding exit/wait status 659 the process receives a "SIGCHLD", EV will fetch the outstanding
277 for all changed/zombie children and call the callback. 660 exit/wait status for all changed/zombie children and call the
661 callback.
278 662
279 Unlike all other callbacks, this callback will be called with an 663 It is valid (and fully supported) to install a child watcher after a
280 additional third argument which is the exit status. See the 664 child has exited but before the event loop has started its next
281 "waitpid" function for details. 665 iteration (for example, first you "fork", then the new child process
666 might exit, and only then do you install a child watcher in the
667 parent for the new pid).
282 668
669 You can access both exit (or tracing) status and pid by using the
670 "rstatus" and "rpid" methods on the watcher object.
671
283 You can have as many pid watchers per pid as you want. 672 You can have as many pid watchers per pid as you want, they will all
673 be called.
284 674
285 The "child_ns" variant doesn't start (activate) the newly created 675 The "child_ns" variant doesn't start (activate) the newly created
286 watcher. 676 watcher.
287 677
288 $w->set ($pid) 678 $w->set ($pid, $trace)
289 Reconfigures the watcher, see the constructor above for details. Can 679 Reconfigures the watcher, see the constructor above for details. Can
290 be at any time. 680 be called at any time.
291 681
682 $current_pid = $w->pid
683 Returns the previously set process id and optionally set a new one.
684
685 $exit_status = $w->rstatus
686 Return the exit/wait status (as returned by waitpid, see the waitpid
687 entry in perlfunc).
688
689 $pid = $w->rpid
690 Return the pid of the awaited child (useful when you have installed
691 a watcher for all pids).
692
693 STAT WATCHERS - did the file attributes just change?
694 $w = EV::stat $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)
698 Call the callback when a file status change has been detected on
699 $path. The $path does not need to exist, changing from "path exists"
700 to "path does not exist" is a status change like any other.
701
702 The $interval is a recommended polling interval for systems where
703 OS-supported change notifications don't exist or are not supported.
704 If you use 0 then an unspecified default is used (which is highly
705 recommended!), which is to be expected to be around five seconds
706 usually.
707
708 This watcher type is not meant for massive numbers of stat watchers,
709 as even with OS-supported change notifications, this can be
710 resource-intensive.
711
712 The "stat_ns" variant doesn't start (activate) the newly created
713 watcher.
714
715 ... = $w->stat
716 This call is very similar to the perl "stat" built-in: It stats
717 (using "lstat") the path specified in the watcher and sets perls
718 stat cache (as well as EV's idea of the current stat values) to the
719 values found.
720
721 In scalar context, a boolean is return indicating success or failure
722 of the stat. In list context, the same 13-value list as with stat is
723 returned (except that the blksize and blocks fields are not
724 reliable).
725
726 In the case of an error, errno is set to "ENOENT" (regardless of the
727 actual error value) and the "nlink" value is forced to zero (if the
728 stat was successful then nlink is guaranteed to be non-zero).
729
730 See also the next two entries for more info.
731
732 ... = $w->attr
733 Just like "$w->stat", but without the initial stat'ing: this returns
734 the values most recently detected by EV. See the next entry for more
735 info.
736
737 ... = $w->prev
738 Just like "$w->stat", but without the initial stat'ing: this returns
739 the previous set of values, before the change.
740
741 That is, when the watcher callback is invoked, "$w->prev" will be
742 set to the values found *before* a change was detected, while
743 "$w->attr" returns the values found leading to the change detection.
744 The difference (if any) between "prev" and "attr" is what triggered
745 the callback.
746
747 If you did something to the filesystem object and do not want to
748 trigger yet another change, you can call "stat" to update EV's idea
749 of what the current attributes are.
750
751 $w->set ($path, $interval)
752 Reconfigures the watcher, see the constructor above for details. Can
753 be called at any time.
754
755 $current_path = $w->path
756 $old_path = $w->path ($new_path)
757 Returns the previously set path and optionally set a new one.
758
759 $current_interval = $w->interval
760 $old_interval = $w->interval ($new_interval)
761 Returns the previously set interval and optionally set a new one.
762 Can be used to query the actual interval used.
763
764 IDLE WATCHERS - when you've got nothing better to do...
292 $w = EV::idle $callback 765 $w = EV::idle $callback
293 $w = EV::idle_ns $callback 766 $w = EV::idle_ns $callback
767 $w = $loop->idle ($callback)
768 $w = $loop->idle_ns ($callback)
294 Call the callback when there are no pending io, timer/periodic, 769 Call the callback when there are no other pending watchers of the
295 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".
296 778
297 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,
298 and they will be called repeatedly until stopped. 780 and they will be called repeatedly until stopped.
299 781
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.
787
300 The "idle_ns" variant doesn't start (activate) the newly created 788 The "idle_ns" variant doesn't start (activate) the newly created
301 watcher. 789 watcher.
302 790
791 PREPARE WATCHERS - customise your event loop!
303 $w = EV::prepare $callback 792 $w = EV::prepare $callback
304 $w = EV::prepare_ns $callback 793 $w = EV::prepare_ns $callback
794 $w = $loop->prepare ($callback)
795 $w = $loop->prepare_ns ($callback)
305 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
306 create/modify any watchers at this point. 797 create/modify any watchers at this point.
307 798
308 See the EV::check watcher, below, for explanations and an example. 799 See the EV::check watcher, below, for explanations and an example.
309 800
310 The "prepare_ns" variant doesn't start (activate) the newly created 801 The "prepare_ns" variant doesn't start (activate) the newly created
311 watcher. 802 watcher.
312 803
804 CHECK WATCHERS - customise your event loop even more!
313 $w = EV::check $callback 805 $w = EV::check $callback
314 $w = EV::check_ns $callback 806 $w = EV::check_ns $callback
807 $w = $loop->check ($callback)
808 $w = $loop->check_ns ($callback)
315 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
316 has gathered events), but before any other callbacks have been 810 has gathered events), but before any other callbacks have been
317 invoked. 811 invoked.
318 812
319 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
320 mainloop: You register a prepare callback and in there, you create 814 mainloop: You register a prepare callback and in there, you create
321 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
322 real-world example of integrating Net::SNMP (with some details left 816 real-world example of integrating Net::SNMP (with some details left
323 out): 817 out):
324 818
… …
328 # do nothing unless active 822 # do nothing unless active
329 $dispatcher->{_event_queue_h} 823 $dispatcher->{_event_queue_h}
330 or return; 824 or return;
331 825
332 # make the dispatcher handle any outstanding stuff 826 # make the dispatcher handle any outstanding stuff
827 ... not shown
333 828
334 # create an IO watcher for each and every socket 829 # create an I/O watcher for each and every socket
335 @snmp_watcher = ( 830 @snmp_watcher = (
336 (map { EV::io $_, EV::READ, sub { } } 831 (map { EV::io $_, EV::READ, sub { } }
337 keys %{ $dispatcher->{_descriptors} }), 832 keys %{ $dispatcher->{_descriptors} }),
833
834 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
835 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
836 0, sub { },
338 ); 837 );
339
340 # if there are any timeouts, also create a timer
341 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
342 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
343 }; 838 };
344 839
345 The callbacks are irrelevant, the only purpose of those watchers is 840 The callbacks are irrelevant (and are not even being called), the
346 to wake up the process as soon as one of those events occurs (socket 841 only purpose of those watchers is to wake up the process as soon as
347 readable, or timer timed out). The corresponding EV::check watcher 842 one of those events occurs (socket readable, or timer timed out).
348 will then clean up: 843 The corresponding EV::check watcher will then clean up:
349 844
350 our $snmp_check = EV::check sub { 845 our $snmp_check = EV::check sub {
351 # destroy all watchers 846 # destroy all watchers
352 @snmp_watcher = (); 847 @snmp_watcher = ();
353 848
354 # make the dispatcher handle any new stuff 849 # make the dispatcher handle any new stuff
850 ... not shown
355 }; 851 };
356 852
357 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
358 watchers are destroyed before this cna happen (remember EV::check 854 watchers are destroyed before this can happen (remember EV::check
359 gets called first). 855 gets called first).
360 856
361 The "check_ns" variant doesn't start (activate) the newly created 857 The "check_ns" variant doesn't start (activate) the newly created
362 watcher. 858 watcher.
363 859
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.
868
869 FORK WATCHERS - the audacity to resume the event loop after a fork
870 Fork watchers are called when a "fork ()" was detected. The invocation
871 is done before the event loop blocks next and before "check" watchers
872 are being called, and only in the child after the fork.
873
874 $w = EV::fork $callback
875 $w = EV::fork_ns $callback
876 $w = $loop->fork ($callback)
877 $w = $loop->fork_ns ($callback)
878 Call the callback before the event loop is resumed in the child
879 process after a fork.
880
881 The "fork_ns" variant doesn't start (activate) the newly created
882 watcher.
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
364THREADS 961ITHREADS
365 Threads are not supported by this in any way. Perl pseudo-threads is 962 Ithreads are not supported by this module in any way. Perl
366 evil stuff and must die. 963 pseudo-threads is evil stuff and must die. Real threads as provided by
964 Coro are fully supported (and enhanced support is available via
965 Coro::EV).
966
967FORK
968 Most of the "improved" event delivering mechanisms of modern operating
969 systems have quite a few problems with fork(2) (to put it bluntly: it is
970 not supported and usually destructive). Libev makes it possible to work
971 around this by having a function that recreates the kernel state after
972 fork in the child.
973
974 On non-win32 platforms, this module requires the pthread_atfork
975 functionality to do this automatically for you. This function is quite
976 buggy on most BSDs, though, so YMMV. The overhead for this is quite
977 negligible, because everything the function currently does is set a flag
978 that is checked only when the event loop gets used the next time, so
979 when you do fork but not use EV, the overhead is minimal.
980
981 On win32, there is no notion of fork so all this doesn't apply, of
982 course.
367 983
368SEE ALSO 984SEE ALSO
369 L<EV::DNS>, L<EV::AnyEvent>. 985 EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous
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.
370 990
371AUTHOR 991AUTHOR
372 Marc Lehmann <schmorp@schmorp.de> 992 Marc Lehmann <schmorp@schmorp.de>
373 http://home.schmorp.de/ 993 http://home.schmorp.de/
374 994

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