| 1 |
=head1 NAME |
| 2 |
|
| 3 |
EV - perl interface to libev, a high performance full-featured event loop |
| 4 |
|
| 5 |
=head1 SYNOPSIS |
| 6 |
|
| 7 |
use EV; |
| 8 |
|
| 9 |
# TIMERS |
| 10 |
|
| 11 |
my $w = EV::timer 2, 0, sub { |
| 12 |
warn "is called after 2s"; |
| 13 |
}; |
| 14 |
|
| 15 |
my $w = EV::timer 2, 2, sub { |
| 16 |
warn "is called roughly every 2s (repeat = 2)"; |
| 17 |
}; |
| 18 |
|
| 19 |
undef $w; # destroy event watcher again |
| 20 |
|
| 21 |
my $w = EV::periodic 0, 60, 0, sub { |
| 22 |
warn "is called every minute, on the minute, exactly"; |
| 23 |
}; |
| 24 |
|
| 25 |
# IO |
| 26 |
|
| 27 |
my $w = EV::io *STDIN, EV::READ, sub { |
| 28 |
my ($w, $revents) = @_; # all callbacks receive the watcher and event mask |
| 29 |
warn "stdin is readable, you entered: ", <STDIN>; |
| 30 |
}; |
| 31 |
|
| 32 |
# SIGNALS |
| 33 |
|
| 34 |
my $w = EV::signal 'QUIT', sub { |
| 35 |
warn "sigquit received\n"; |
| 36 |
}; |
| 37 |
|
| 38 |
# CHILD/PID STATUS CHANGES |
| 39 |
|
| 40 |
my $w = EV::child 666, sub { |
| 41 |
my ($w, $revents) = @_; |
| 42 |
my $status = $w->rstatus; |
| 43 |
}; |
| 44 |
|
| 45 |
# MAINLOOP |
| 46 |
EV::loop; # loop until EV::loop_done is called or all watchers stop |
| 47 |
EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
| 48 |
EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
| 49 |
|
| 50 |
=head1 DESCRIPTION |
| 51 |
|
| 52 |
This module provides an interface to libev |
| 53 |
(L<http://software.schmorp.de/pkg/libev.html>). |
| 54 |
|
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=cut |
| 56 |
|
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package EV; |
| 58 |
|
| 59 |
use strict; |
| 60 |
|
| 61 |
BEGIN { |
| 62 |
our $VERSION = '0.7'; |
| 63 |
use XSLoader; |
| 64 |
XSLoader::load "EV", $VERSION; |
| 65 |
} |
| 66 |
|
| 67 |
@EV::Io::ISA = |
| 68 |
@EV::Timer::ISA = |
| 69 |
@EV::Periodic::ISA = |
| 70 |
@EV::Signal::ISA = |
| 71 |
@EV::Idle::ISA = |
| 72 |
@EV::Prepare::ISA = |
| 73 |
@EV::Check::ISA = |
| 74 |
@EV::Child::ISA = "EV::Watcher"; |
| 75 |
|
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=head1 BASIC INTERFACE |
| 77 |
|
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=over 4 |
| 79 |
|
| 80 |
=item $EV::DIED |
| 81 |
|
| 82 |
Must contain a reference to a function that is called when a callback |
| 83 |
throws an exception (with $@ containing thr error). The default prints an |
| 84 |
informative message and continues. |
| 85 |
|
| 86 |
If this callback throws an exception it will be silently ignored. |
| 87 |
|
| 88 |
=item $time = EV::time |
| 89 |
|
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Returns the current time in (fractional) seconds since the epoch. |
| 91 |
|
| 92 |
=item $time = EV::now |
| 93 |
|
| 94 |
Returns the time the last event loop iteration has been started. This |
| 95 |
is the time that (relative) timers are based on, and refering to it is |
| 96 |
usually faster then calling EV::time. |
| 97 |
|
| 98 |
=item $method = EV::ev_method |
| 99 |
|
| 100 |
Returns an integer describing the backend used by libev (EV::METHOD_SELECT |
| 101 |
or EV::METHOD_EPOLL). |
| 102 |
|
| 103 |
=item EV::loop [$flags] |
| 104 |
|
| 105 |
Begin checking for events and calling callbacks. It returns when a |
| 106 |
callback calls EV::loop_done. |
| 107 |
|
| 108 |
The $flags argument can be one of the following: |
| 109 |
|
| 110 |
0 as above |
| 111 |
EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
| 112 |
EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
| 113 |
|
| 114 |
=item EV::loop_done [$how] |
| 115 |
|
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When called with no arguments or an argument of 1, makes the innermost |
| 117 |
call to EV::loop return. |
| 118 |
|
| 119 |
When called with an agrument of 2, all calls to EV::loop will return as |
| 120 |
fast as possible. |
| 121 |
|
| 122 |
=back |
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|
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=head2 WATCHER |
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|
| 126 |
A watcher is an object that gets created to record your interest in some |
| 127 |
event. For instance, if you want to wait for STDIN to become readable, you |
| 128 |
would create an EV::io watcher for that: |
| 129 |
|
| 130 |
my $watcher = EV::io *STDIN, EV::READ, sub { |
| 131 |
my ($watcher, $revents) = @_; |
| 132 |
warn "yeah, STDIN should not be readable without blocking!\n" |
| 133 |
}; |
| 134 |
|
| 135 |
All watchers can be active (waiting for events) or inactive (paused). Only |
| 136 |
active watchers will have their callbacks invoked. All callbacks will be |
| 137 |
called with at least two arguments: the watcher and a bitmask of received |
| 138 |
events. |
| 139 |
|
| 140 |
Each watcher type has its associated bit in revents, so you can use the |
| 141 |
same callback for multiple watchers. The event mask is named after the |
| 142 |
type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
| 143 |
EV::periodic sets EV::PERIODIC and so on, with the exception of IO events |
| 144 |
(which can set both EV::READ and EV::WRITE bits), and EV::timer (which |
| 145 |
uses EV::TIMEOUT). |
| 146 |
|
| 147 |
In the rare case where one wants to create a watcher but not start it at |
| 148 |
the same time, each constructor has a variant with a trailing C<_ns> in |
| 149 |
its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. |
| 150 |
|
| 151 |
Please note that a watcher will automatically be stopped when the watcher |
| 152 |
object is destroyed, so you I<need> to keep the watcher objects returned by |
| 153 |
the constructors. |
| 154 |
|
| 155 |
Also, all methods changing some aspect of a watcher (->set, ->priority, |
| 156 |
->fh and so on) automatically stop and start it again if it is active, |
| 157 |
which means pending events get lost. |
| 158 |
|
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=head2 WATCHER TYPES |
| 160 |
|
| 161 |
Now lets move to the existing watcher types and asociated methods. |
| 162 |
|
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The following methods are available for all watchers. Then followes a |
| 164 |
description of each watcher constructor (EV::io, EV::timer, EV::periodic, |
| 165 |
EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by |
| 166 |
any type-specific methods (if any). |
| 167 |
|
| 168 |
=over 4 |
| 169 |
|
| 170 |
=item $w->start |
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|
| 172 |
Starts a watcher if it isn't active already. Does nothing to an already |
| 173 |
active watcher. By default, all watchers start out in the active state |
| 174 |
(see the description of the C<_ns> variants if you need stopped watchers). |
| 175 |
|
| 176 |
=item $w->stop |
| 177 |
|
| 178 |
Stop a watcher if it is active. Also clear any pending events (events that |
| 179 |
have been received but that didn't yet result in a callback invocation), |
| 180 |
regardless of wether the watcher was active or not. |
| 181 |
|
| 182 |
=item $bool = $w->is_active |
| 183 |
|
| 184 |
Returns true if the watcher is active, false otherwise. |
| 185 |
|
| 186 |
=item $current_data = $w->data |
| 187 |
|
| 188 |
=item $old_data = $w->data ($new_data) |
| 189 |
|
| 190 |
Queries a freely usable data scalar on the watcher and optionally changes |
| 191 |
it. This is a way to associate custom data with a watcher: |
| 192 |
|
| 193 |
my $w = EV::timer 60, 0, sub { |
| 194 |
warn $_[0]->data; |
| 195 |
}; |
| 196 |
$w->data ("print me!"); |
| 197 |
|
| 198 |
=item $current_cb = $w->cb |
| 199 |
|
| 200 |
=item $old_cb = $w->cb ($new_cb) |
| 201 |
|
| 202 |
Queries the callback on the watcher and optionally changes it. You can do |
| 203 |
this at any time without the watcher restarting. |
| 204 |
|
| 205 |
=item $current_priority = $w->priority |
| 206 |
|
| 207 |
=item $old_priority = $w->priority ($new_priority) |
| 208 |
|
| 209 |
Queries the priority on the watcher and optionally changes it. Pending |
| 210 |
watchers with higher priority will be invoked first. The valid range of |
| 211 |
priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default |
| 212 |
-2). If the priority is outside this range it will automatically be |
| 213 |
normalised to the nearest valid priority. |
| 214 |
|
| 215 |
The default priority of any newly-created weatcher is 0. |
| 216 |
|
| 217 |
=item $w->trigger ($revents) |
| 218 |
|
| 219 |
Call the callback *now* with the given event mask. |
| 220 |
|
| 221 |
|
| 222 |
=item $w = EV::io $fileno_or_fh, $eventmask, $callback |
| 223 |
|
| 224 |
=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
| 225 |
|
| 226 |
As long as the returned watcher object is alive, call the C<$callback> |
| 227 |
when the events specified in C<$eventmask>. |
| 228 |
|
| 229 |
The $eventmask can be one or more of these constants ORed together: |
| 230 |
|
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EV::READ wait until read() wouldn't block anymore |
| 232 |
EV::WRITE wait until write() wouldn't block anymore |
| 233 |
|
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The C<io_ns> variant doesn't start (activate) the newly created watcher. |
| 235 |
|
| 236 |
=item $w->set ($fileno_or_fh, $eventmask) |
| 237 |
|
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Reconfigures the watcher, see the constructor above for details. Can be |
| 239 |
called at any time. |
| 240 |
|
| 241 |
=item $current_fh = $w->fh |
| 242 |
|
| 243 |
=item $old_fh = $w->fh ($new_fh) |
| 244 |
|
| 245 |
Returns the previously set filehandle and optionally set a new one. |
| 246 |
|
| 247 |
=item $current_eventmask = $w->events |
| 248 |
|
| 249 |
=item $old_eventmask = $w->events ($new_eventmask) |
| 250 |
|
| 251 |
Returns the previously set event mask and optionally set a new one. |
| 252 |
|
| 253 |
|
| 254 |
=item $w = EV::timer $after, $repeat, $callback |
| 255 |
|
| 256 |
=item $w = EV::timer_ns $after, $repeat, $callback |
| 257 |
|
| 258 |
Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, |
| 259 |
the timer will be restarted (with the $repeat value as $after) after the |
| 260 |
callback returns. |
| 261 |
|
| 262 |
This means that the callback would be called roughly after C<$after> |
| 263 |
seconds, and then every C<$repeat> seconds. "Roughly" because the time of |
| 264 |
callback processing is not taken into account, so the timer will slowly |
| 265 |
drift. If that isn't acceptable, look at EV::periodic. |
| 266 |
|
| 267 |
The timer is based on a monotonic clock, that is if somebody is sitting |
| 268 |
in front of the machine while the timer is running and changes the system |
| 269 |
clock, the timer will nevertheless run (roughly) the same time. |
| 270 |
|
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The C<timer_ns> variant doesn't start (activate) the newly created watcher. |
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|
| 273 |
=item $w->set ($after, $repeat) |
| 274 |
|
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Reconfigures the watcher, see the constructor above for details. Can be at |
| 276 |
any time. |
| 277 |
|
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=item $w->again |
| 279 |
|
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Similar to the C<start> method, but has special semantics for repeating timers: |
| 281 |
|
| 282 |
If the timer is active and repeating, reset the timeout to occur |
| 283 |
C<$repeat> seconds after now. |
| 284 |
|
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If the timer is active and non-repeating, it will be stopped. |
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|
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If the timer is in active and repeating, start it. |
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|
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Otherwise do nothing. |
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|
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This behaviour is useful when you have a timeout for some IO |
| 292 |
operation. You create a timer object with the same value for C<$after> and |
| 293 |
C<$repeat>, and then, in the read/write watcher, run the C<again> method |
| 294 |
on the timeout. |
| 295 |
|
| 296 |
|
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=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
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|
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=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
| 300 |
|
| 301 |
Similar to EV::timer, but is not based on relative timeouts but on |
| 302 |
absolute times. Apart from creating "simple" timers that trigger "at" the |
| 303 |
specified time, it can also be used for non-drifting absolute timers and |
| 304 |
more complex, cron-like, setups that are not adversely affected by time |
| 305 |
jumps (i.e. when the system clock is changed by explicit date -s or other |
| 306 |
means such as ntpd). It is also the most complex watcher type in EV. |
| 307 |
|
| 308 |
It has three distinct "modes": |
| 309 |
|
| 310 |
=over 4 |
| 311 |
|
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=item * absolute timer ($interval = $reschedule_cb = 0) |
| 313 |
|
| 314 |
This time simply fires at the wallclock time C<$at> and doesn't repeat. It |
| 315 |
will not adjust when a time jump occurs, that is, if it is to be run |
| 316 |
at January 1st 2011 then it will run when the system time reaches or |
| 317 |
surpasses this time. |
| 318 |
|
| 319 |
=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) |
| 320 |
|
| 321 |
In this mode the watcher will always be scheduled to time out at the |
| 322 |
next C<$at + N * $interval> time (for some integer N) and then repeat, |
| 323 |
regardless of any time jumps. |
| 324 |
|
| 325 |
This can be used to create timers that do not drift with respect to system |
| 326 |
time: |
| 327 |
|
| 328 |
my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; |
| 329 |
|
| 330 |
That doesn't mean there will always be 3600 seconds in between triggers, |
| 331 |
but only that the the clalback will be called when the system time shows a |
| 332 |
full hour (UTC). |
| 333 |
|
| 334 |
Another way to think about it (for the mathematically inclined) is that |
| 335 |
EV::periodic will try to run the callback in this mode at the next |
| 336 |
possible time where C<$time = $at (mod $interval)>, regardless of any time |
| 337 |
jumps. |
| 338 |
|
| 339 |
=item * manual reschedule mode ($reschedule_cb = coderef) |
| 340 |
|
| 341 |
In this mode $interval and $at are both being ignored. Instead, each time |
| 342 |
the periodic watcher gets scheduled, the first callback ($reschedule_cb) |
| 343 |
will be called with the watcher as first, and the current time as second |
| 344 |
argument. |
| 345 |
|
| 346 |
I<This callback MUST NOT stop or destroy this or any other periodic |
| 347 |
watcher, ever>. If you need to stop it, return 1e30 and stop it |
| 348 |
afterwards. |
| 349 |
|
| 350 |
It must return the next time to trigger, based on the passed time value |
| 351 |
(that is, the lowest time value larger than to the second argument). It |
| 352 |
will usually be called just before the callback will be triggered, but |
| 353 |
might be called at other times, too. |
| 354 |
|
| 355 |
This can be used to create very complex timers, such as a timer that |
| 356 |
triggers on each midnight, local time (actually 24 hours after the last |
| 357 |
midnight, to keep the example simple. If you know a way to do it correctly |
| 358 |
in about the same space (without requiring elaborate modules), drop me a |
| 359 |
note :): |
| 360 |
|
| 361 |
my $daily = EV::periodic 0, 0, sub { |
| 362 |
my ($w, $now) = @_; |
| 363 |
|
| 364 |
use Time::Local (); |
| 365 |
my (undef, undef, undef, $d, $m, $y) = localtime $now; |
| 366 |
86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y |
| 367 |
}, sub { |
| 368 |
print "it's midnight or likely shortly after, now\n"; |
| 369 |
}; |
| 370 |
|
| 371 |
=back |
| 372 |
|
| 373 |
The C<periodic_ns> variant doesn't start (activate) the newly created watcher. |
| 374 |
|
| 375 |
=item $w->set ($at, $interval, $reschedule_cb) |
| 376 |
|
| 377 |
Reconfigures the watcher, see the constructor above for details. Can be at |
| 378 |
any time. |
| 379 |
|
| 380 |
=item $w->again |
| 381 |
|
| 382 |
Simply stops and starts the watcher again. |
| 383 |
|
| 384 |
|
| 385 |
=item $w = EV::signal $signal, $callback |
| 386 |
|
| 387 |
=item $w = EV::signal_ns $signal, $callback |
| 388 |
|
| 389 |
Call the callback when $signal is received (the signal can be specified |
| 390 |
by number or by name, just as with kill or %SIG). |
| 391 |
|
| 392 |
EV will grab the signal for the process (the kernel only allows one |
| 393 |
component to receive a signal at a time) when you start a signal watcher, |
| 394 |
and removes it again when you stop it. Perl does the same when you |
| 395 |
add/remove callbacks to %SIG, so watch out. |
| 396 |
|
| 397 |
You can have as many signal watchers per signal as you want. |
| 398 |
|
| 399 |
The C<signal_ns> variant doesn't start (activate) the newly created watcher. |
| 400 |
|
| 401 |
=item $w->set ($signal) |
| 402 |
|
| 403 |
Reconfigures the watcher, see the constructor above for details. Can be at |
| 404 |
any time. |
| 405 |
|
| 406 |
=item $current_signum = $w->signal |
| 407 |
|
| 408 |
=item $old_signum = $w->signal ($new_signal) |
| 409 |
|
| 410 |
Returns the previously set signal (always as a number not name) and |
| 411 |
optionally set a new one. |
| 412 |
|
| 413 |
|
| 414 |
=item $w = EV::child $pid, $callback |
| 415 |
|
| 416 |
=item $w = EV::child_ns $pid, $callback |
| 417 |
|
| 418 |
Call the callback when a status change for pid C<$pid> (or any pid |
| 419 |
if C<$pid> is 0) has been received. More precisely: when the process |
| 420 |
receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all |
| 421 |
changed/zombie children and call the callback. |
| 422 |
|
| 423 |
You can access both status and pid by using the C<rstatus> and C<rpid> |
| 424 |
methods on the watcher object. |
| 425 |
|
| 426 |
You can have as many pid watchers per pid as you want. |
| 427 |
|
| 428 |
The C<child_ns> variant doesn't start (activate) the newly created watcher. |
| 429 |
|
| 430 |
=item $w->set ($pid) |
| 431 |
|
| 432 |
Reconfigures the watcher, see the constructor above for details. Can be at |
| 433 |
any time. |
| 434 |
|
| 435 |
=item $current_pid = $w->pid |
| 436 |
|
| 437 |
=item $old_pid = $w->pid ($new_pid) |
| 438 |
|
| 439 |
Returns the previously set process id and optionally set a new one. |
| 440 |
|
| 441 |
=item $exit_status = $w->rstatus |
| 442 |
|
| 443 |
Return the exit/wait status (as returned by waitpid, see the waitpid entry |
| 444 |
in perlfunc). |
| 445 |
|
| 446 |
=item $pid = $w->rpid |
| 447 |
|
| 448 |
Return the pid of the awaited child (useful when you have installed a |
| 449 |
watcher for all pids). |
| 450 |
|
| 451 |
|
| 452 |
=item $w = EV::idle $callback |
| 453 |
|
| 454 |
=item $w = EV::idle_ns $callback |
| 455 |
|
| 456 |
Call the callback when there are no pending io, timer/periodic, signal or |
| 457 |
child events, i.e. when the process is idle. |
| 458 |
|
| 459 |
The process will not block as long as any idle watchers are active, and |
| 460 |
they will be called repeatedly until stopped. |
| 461 |
|
| 462 |
The C<idle_ns> variant doesn't start (activate) the newly created watcher. |
| 463 |
|
| 464 |
|
| 465 |
=item $w = EV::prepare $callback |
| 466 |
|
| 467 |
=item $w = EV::prepare_ns $callback |
| 468 |
|
| 469 |
Call the callback just before the process would block. You can still |
| 470 |
create/modify any watchers at this point. |
| 471 |
|
| 472 |
See the EV::check watcher, below, for explanations and an example. |
| 473 |
|
| 474 |
The C<prepare_ns> variant doesn't start (activate) the newly created watcher. |
| 475 |
|
| 476 |
|
| 477 |
=item $w = EV::check $callback |
| 478 |
|
| 479 |
=item $w = EV::check_ns $callback |
| 480 |
|
| 481 |
Call the callback just after the process wakes up again (after it has |
| 482 |
gathered events), but before any other callbacks have been invoked. |
| 483 |
|
| 484 |
This is used to integrate other event-based software into the EV |
| 485 |
mainloop: You register a prepare callback and in there, you create io and |
| 486 |
timer watchers as required by the other software. Here is a real-world |
| 487 |
example of integrating Net::SNMP (with some details left out): |
| 488 |
|
| 489 |
our @snmp_watcher; |
| 490 |
|
| 491 |
our $snmp_prepare = EV::prepare sub { |
| 492 |
# do nothing unless active |
| 493 |
$dispatcher->{_event_queue_h} |
| 494 |
or return; |
| 495 |
|
| 496 |
# make the dispatcher handle any outstanding stuff |
| 497 |
|
| 498 |
# create an IO watcher for each and every socket |
| 499 |
@snmp_watcher = ( |
| 500 |
(map { EV::io $_, EV::READ, sub { } } |
| 501 |
keys %{ $dispatcher->{_descriptors} }), |
| 502 |
); |
| 503 |
|
| 504 |
# if there are any timeouts, also create a timer |
| 505 |
push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { } |
| 506 |
if $event->[Net::SNMP::Dispatcher::_ACTIVE]; |
| 507 |
}; |
| 508 |
|
| 509 |
The callbacks are irrelevant, the only purpose of those watchers is |
| 510 |
to wake up the process as soon as one of those events occurs (socket |
| 511 |
readable, or timer timed out). The corresponding EV::check watcher will then |
| 512 |
clean up: |
| 513 |
|
| 514 |
our $snmp_check = EV::check sub { |
| 515 |
# destroy all watchers |
| 516 |
@snmp_watcher = (); |
| 517 |
|
| 518 |
# make the dispatcher handle any new stuff |
| 519 |
}; |
| 520 |
|
| 521 |
The callbacks of the created watchers will not be called as the watchers |
| 522 |
are destroyed before this cna happen (remember EV::check gets called |
| 523 |
first). |
| 524 |
|
| 525 |
The C<check_ns> variant doesn't start (activate) the newly created watcher. |
| 526 |
|
| 527 |
=back |
| 528 |
|
| 529 |
=head1 THREADS |
| 530 |
|
| 531 |
Threads are not supported by this in any way. Perl pseudo-threads is evil |
| 532 |
stuff and must die. |
| 533 |
|
| 534 |
=cut |
| 535 |
|
| 536 |
our $DIED = sub { |
| 537 |
warn "EV: error in callback (ignoring): $@"; |
| 538 |
}; |
| 539 |
|
| 540 |
default_loop |
| 541 |
or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; |
| 542 |
|
| 543 |
1; |
| 544 |
|
| 545 |
=head1 SEE ALSO |
| 546 |
|
| 547 |
L<EV::DNS>, L<EV::AnyEvent>. |
| 548 |
|
| 549 |
=head1 AUTHOR |
| 550 |
|
| 551 |
Marc Lehmann <schmorp@schmorp.de> |
| 552 |
http://home.schmorp.de/ |
| 553 |
|
| 554 |
=cut |
| 555 |
|
