| 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, 1, sub { |
| 16 |
warn "is called roughly every 2s (repeat = 1)"; |
| 17 |
}; |
| 18 |
|
| 19 |
undef $w; # destroy event watcher again |
| 20 |
|
| 21 |
my $w = EV::periodic 0, 60, 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 get the watcher object 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 |
my $w = EV::signal 3, sub { |
| 39 |
warn "sigquit received (this is GNU/Linux, right?)\n"; |
| 40 |
}; |
| 41 |
|
| 42 |
# CHILD/PID STATUS CHANGES |
| 43 |
|
| 44 |
my $w = EV::child 666, sub { |
| 45 |
my ($w, $revents, $status) = @_; |
| 46 |
}; |
| 47 |
|
| 48 |
# MAINLOOP |
| 49 |
EV::loop; # loop until EV::loop_done is called |
| 50 |
EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
| 51 |
EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
| 52 |
|
| 53 |
=head1 DESCRIPTION |
| 54 |
|
| 55 |
This module provides an interface to libev |
| 56 |
(L<http://software.schmorp.de/pkg/libev.html>). |
| 57 |
|
| 58 |
=cut |
| 59 |
|
| 60 |
package EV; |
| 61 |
|
| 62 |
use strict; |
| 63 |
|
| 64 |
BEGIN { |
| 65 |
our $VERSION = '0.1'; |
| 66 |
use XSLoader; |
| 67 |
XSLoader::load "EV", $VERSION; |
| 68 |
} |
| 69 |
|
| 70 |
@EV::Io::ISA = |
| 71 |
@EV::Timer::ISA = |
| 72 |
@EV::Periodic::ISA = |
| 73 |
@EV::Signal::ISA = |
| 74 |
@EV::Idle::ISA = |
| 75 |
@EV::Prepare::ISA = |
| 76 |
@EV::Check::ISA = |
| 77 |
@EV::Child::ISA = "EV::Watcher"; |
| 78 |
|
| 79 |
=head1 BASIC INTERFACE |
| 80 |
|
| 81 |
=over 4 |
| 82 |
|
| 83 |
=item $EV::DIED |
| 84 |
|
| 85 |
Must contain a reference to a function that is called when a callback |
| 86 |
throws an exception (with $@ containing thr error). The default prints an |
| 87 |
informative message and continues. |
| 88 |
|
| 89 |
If this callback throws an exception it will be silently ignored. |
| 90 |
|
| 91 |
=item $time = EV::time |
| 92 |
|
| 93 |
Returns the current time in (fractional) seconds since the epoch. |
| 94 |
|
| 95 |
=item $time = EV::now |
| 96 |
|
| 97 |
Returns the time the last event loop iteration has been started. This |
| 98 |
is the time that (relative) timers are based on, and refering to it is |
| 99 |
usually faster then calling EV::time. |
| 100 |
|
| 101 |
=item $method = EV::ev_method |
| 102 |
|
| 103 |
Returns an integer describing the backend used by libev (EV::METHOD_SELECT |
| 104 |
or EV::METHOD_EPOLL). |
| 105 |
|
| 106 |
=item EV::loop [$flags] |
| 107 |
|
| 108 |
Begin checking for events and calling callbacks. It returns when a |
| 109 |
callback calls EV::loop_done. |
| 110 |
|
| 111 |
The $flags argument can be one of the following: |
| 112 |
|
| 113 |
0 as above |
| 114 |
EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
| 115 |
EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
| 116 |
|
| 117 |
=item EV::loop_done [$how] |
| 118 |
|
| 119 |
When called with no arguments or an argument of 1, makes the innermost |
| 120 |
call to EV::loop return. |
| 121 |
|
| 122 |
When called with an agrument of 2, all calls to EV::loop will return as |
| 123 |
fast as possible. |
| 124 |
|
| 125 |
=back |
| 126 |
|
| 127 |
=head2 WATCHER |
| 128 |
|
| 129 |
A watcher is an object that gets created to record your interest in some |
| 130 |
event. For instance, if you want to wait for STDIN to become readable, you |
| 131 |
would create an EV::io watcher for that: |
| 132 |
|
| 133 |
my $watcher = EV::io *STDIN, EV::READ, sub { |
| 134 |
my ($watcher, $revents) = @_; |
| 135 |
warn "yeah, STDIN should not be readable without blocking!\n" |
| 136 |
}; |
| 137 |
|
| 138 |
All watchers can be active (waiting for events) or inactive (paused). Only |
| 139 |
active watchers will have their callbacks invoked. All callbacks will be |
| 140 |
called with at least two arguments: the watcher and a bitmask of received |
| 141 |
events. |
| 142 |
|
| 143 |
Each watcher type has its associated bit in revents, so you can use the |
| 144 |
same callback for multiple watchers. The event mask is named after the |
| 145 |
type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
| 146 |
EV::periodic sets EV::PERIODIC and so on, with the exception of IO events |
| 147 |
(which can set both EV::READ and EV::WRITE bits), and EV::timer (which |
| 148 |
uses EV::TIMEOUT). |
| 149 |
|
| 150 |
In the rare case where one wants to create a watcher but not start it at |
| 151 |
the same time, each constructor has a variant with a trailing C<_ns> in |
| 152 |
its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. |
| 153 |
|
| 154 |
Please note that a watcher will automatically be stopped when the watcher |
| 155 |
object is returned, so you I<need> to keep the watcher objects returned by |
| 156 |
the constructors. |
| 157 |
|
| 158 |
=head2 WATCHER TYPES |
| 159 |
|
| 160 |
Now lets move to the existing watcher types and asociated methods. |
| 161 |
|
| 162 |
The following methods are available for all watchers. Then followes a |
| 163 |
description of each watcher constructor (EV::io, EV::timer, EV::periodic, |
| 164 |
EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by |
| 165 |
any type-specific methods (if any). |
| 166 |
|
| 167 |
=over 4 |
| 168 |
|
| 169 |
=item $w->start |
| 170 |
|
| 171 |
Starts a watcher if it isn't active already. Does nothing to an already |
| 172 |
active watcher. By default, all watchers start out in the active state |
| 173 |
(see the description of the C<_ns> variants if you need stopped watchers). |
| 174 |
|
| 175 |
=item $w->stop |
| 176 |
|
| 177 |
Stop a watcher if it is active. Also clear any pending events (events that |
| 178 |
have been received but that didn't yet result in a callback invocation), |
| 179 |
regardless of wether the watcher was active or not. |
| 180 |
|
| 181 |
=item $bool = $w->is_active |
| 182 |
|
| 183 |
Returns true if the watcher is active, false otherwise. |
| 184 |
|
| 185 |
=item $current_cb = $w->cb |
| 186 |
|
| 187 |
=item $old_cb = $w->cb ($new_cb) |
| 188 |
|
| 189 |
Queries the callback on the watcher and optionally changes it. You cna do |
| 190 |
this at any time. |
| 191 |
|
| 192 |
=item $w->trigger ($revents) |
| 193 |
|
| 194 |
Call the callback *now* with the given event mask. |
| 195 |
|
| 196 |
|
| 197 |
=item $w = EV::io $fileno_or_fh, $eventmask, $callback |
| 198 |
|
| 199 |
=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
| 200 |
|
| 201 |
As long as the returned watcher object is alive, call the C<$callback> |
| 202 |
when the events specified in C<$eventmask>. |
| 203 |
|
| 204 |
The $eventmask can be one or more of these constants ORed together: |
| 205 |
|
| 206 |
EV::READ wait until read() wouldn't block anymore |
| 207 |
EV::WRITE wait until write() wouldn't block anymore |
| 208 |
|
| 209 |
The C<io_ns> variant doesn't start (activate) the newly created watcher. |
| 210 |
|
| 211 |
=item $w->set ($fileno_or_fh, $eventmask) |
| 212 |
|
| 213 |
Reconfigures the watcher, see the constructor above for details. Can be |
| 214 |
called at any time. |
| 215 |
|
| 216 |
=item $current_fh = $w->fh |
| 217 |
|
| 218 |
=item $old_fh = $w->fh ($new_fh) |
| 219 |
|
| 220 |
Returns the previously set filehandle and optionally set a new one. |
| 221 |
|
| 222 |
=item $current_eventmask = $w->events |
| 223 |
|
| 224 |
=item $old_eventmask = $w->events ($new_eventmask) |
| 225 |
|
| 226 |
Returns the previously set event mask and optionally set a new one. |
| 227 |
|
| 228 |
|
| 229 |
=item $w = EV::timer $after, $repeat, $callback |
| 230 |
|
| 231 |
=item $w = EV::timer_ns $after, $repeat, $callback |
| 232 |
|
| 233 |
Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, |
| 234 |
the timer will be restarted (with the $repeat value as $after) after the |
| 235 |
callback returns. |
| 236 |
|
| 237 |
This means that the callback would be called roughly after C<$after> |
| 238 |
seconds, and then every C<$repeat> seconds. "Roughly" because the time of |
| 239 |
callback processing is not taken into account, so the timer will slowly |
| 240 |
drift. If that isn't acceptable, look at EV::periodic. |
| 241 |
|
| 242 |
The timer is based on a monotonic clock, that is if somebody is sitting |
| 243 |
in front of the machine while the timer is running and changes the system |
| 244 |
clock, the timer will nevertheless run (roughly) the same time. |
| 245 |
|
| 246 |
The C<timer_ns> variant doesn't start (activate) the newly created watcher. |
| 247 |
|
| 248 |
=item $w->set ($after, $repeat) |
| 249 |
|
| 250 |
Reconfigures the watcher, see the constructor above for details. Can be at |
| 251 |
any time. |
| 252 |
|
| 253 |
=item $w->again |
| 254 |
|
| 255 |
Similar to the C<start> method, but has special semantics for repeating timers: |
| 256 |
|
| 257 |
If the timer is active and repeating, reset the timeout to occur |
| 258 |
C<$repeat> seconds after now. |
| 259 |
|
| 260 |
If the timer is active and non-repeating, it will be stopped. |
| 261 |
|
| 262 |
If the timer is in active and repeating, start it. |
| 263 |
|
| 264 |
Otherwise do nothing. |
| 265 |
|
| 266 |
This behaviour is useful when you have a timeout for some IO |
| 267 |
operation. You create a timer object with the same value for C<$after> and |
| 268 |
C<$repeat>, and then, in the read/write watcher, run the C<again> method |
| 269 |
on the timeout. |
| 270 |
|
| 271 |
|
| 272 |
=item $w = EV::periodic $at, $interval, $callback |
| 273 |
|
| 274 |
=item $w = EV::periodic_ns $at, $interval, $callback |
| 275 |
|
| 276 |
Similar to EV::timer, but the time is given as an absolute point in time |
| 277 |
(C<$at>), plus an optional C<$interval>. |
| 278 |
|
| 279 |
If the C<$interval> is zero, then the callback will be called at the time |
| 280 |
C<$at> if that is in the future, or as soon as possible if it is in the |
| 281 |
past. It will not automatically repeat. |
| 282 |
|
| 283 |
If the C<$interval> is nonzero, then the watcher will always be scheduled |
| 284 |
to time out at the next C<$at + N * $interval> time. |
| 285 |
|
| 286 |
This can be used to schedule a callback to run at very regular intervals, |
| 287 |
as long as the processing time is less then the interval (otherwise |
| 288 |
obviously events will be skipped). |
| 289 |
|
| 290 |
Another way to think about it (for the mathematically inclined) is that |
| 291 |
EV::periodic will try to run the callback at the next possible time where |
| 292 |
C<$time = $at (mod $interval)>, regardless of any time jumps. |
| 293 |
|
| 294 |
This periodic timer is based on "wallclock time", that is, if the clock |
| 295 |
changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at |
| 296 |
the specified time. This means it will never drift (it might jitter, but |
| 297 |
it will not drift). |
| 298 |
|
| 299 |
The C<periodic_ns> variant doesn't start (activate) the newly created watcher. |
| 300 |
|
| 301 |
=item $w->set ($at, $interval) |
| 302 |
|
| 303 |
Reconfigures the watcher, see the constructor above for details. Can be at |
| 304 |
any time. |
| 305 |
|
| 306 |
|
| 307 |
=item $w = EV::signal $signal, $callback |
| 308 |
|
| 309 |
=item $w = EV::signal_ns $signal, $callback |
| 310 |
|
| 311 |
Call the callback when $signal is received (the signal can be specified |
| 312 |
by number or by name, just as with kill or %SIG). |
| 313 |
|
| 314 |
EV will grab the signal for the process (the kernel only allows one |
| 315 |
component to receive a signal at a time) when you start a signal watcher, |
| 316 |
and removes it again when you stop it. Perl does the same when you |
| 317 |
add/remove callbacks to %SIG, so watch out. |
| 318 |
|
| 319 |
You can have as many signal watchers per signal as you want. |
| 320 |
|
| 321 |
The C<signal_ns> variant doesn't start (activate) the newly created watcher. |
| 322 |
|
| 323 |
=item $w->set ($signal) |
| 324 |
|
| 325 |
Reconfigures the watcher, see the constructor above for details. Can be at |
| 326 |
any time. |
| 327 |
|
| 328 |
|
| 329 |
=item $w = EV::child $pid, $callback |
| 330 |
|
| 331 |
=item $w = EV::child_ns $pid, $callback |
| 332 |
|
| 333 |
Call the callback when a status change for pid C<$pid> (or any pid |
| 334 |
if C<$pid> is 0) has been received. More precisely: when the process |
| 335 |
receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all |
| 336 |
changed/zombie children and call the callback. |
| 337 |
|
| 338 |
Unlike all other callbacks, this callback will be called with an |
| 339 |
additional third argument which is the exit status. See the C<waitpid> |
| 340 |
function for details. |
| 341 |
|
| 342 |
You can have as many pid watchers per pid as you want. |
| 343 |
|
| 344 |
The C<child_ns> variant doesn't start (activate) the newly created watcher. |
| 345 |
|
| 346 |
=item $w->set ($pid) |
| 347 |
|
| 348 |
Reconfigures the watcher, see the constructor above for details. Can be at |
| 349 |
any time. |
| 350 |
|
| 351 |
|
| 352 |
=item $w = EV::idle $callback |
| 353 |
|
| 354 |
=item $w = EV::idle_ns $callback |
| 355 |
|
| 356 |
Call the callback when there are no pending io, timer/periodic, signal or |
| 357 |
child events, i.e. when the process is idle. |
| 358 |
|
| 359 |
The process will not block as long as any idle watchers are active, and |
| 360 |
they will be called repeatedly until stopped. |
| 361 |
|
| 362 |
The C<idle_ns> variant doesn't start (activate) the newly created watcher. |
| 363 |
|
| 364 |
|
| 365 |
=item $w = EV::prepare $callback |
| 366 |
|
| 367 |
=item $w = EV::prepare_ns $callback |
| 368 |
|
| 369 |
Call the callback just before the process would block. You can still |
| 370 |
create/modify any watchers at this point. |
| 371 |
|
| 372 |
See the EV::check watcher, below, for explanations and an example. |
| 373 |
|
| 374 |
The C<prepare_ns> variant doesn't start (activate) the newly created watcher. |
| 375 |
|
| 376 |
|
| 377 |
=item $w = EV::check $callback |
| 378 |
|
| 379 |
=item $w = EV::check_ns $callback |
| 380 |
|
| 381 |
Call the callback just after the process wakes up again (after it has |
| 382 |
gathered events), but before any other callbacks have been invoked. |
| 383 |
|
| 384 |
This is used to integrate other event-based software into the EV |
| 385 |
mainloop: You register a prepare callback and in there, you create io and |
| 386 |
timer watchers as required by the other software. Here is a real-world |
| 387 |
example of integrating Net::SNMP (with some details left out): |
| 388 |
|
| 389 |
our @snmp_watcher; |
| 390 |
|
| 391 |
our $snmp_prepare = EV::prepare sub { |
| 392 |
# do nothing unless active |
| 393 |
$dispatcher->{_event_queue_h} |
| 394 |
or return; |
| 395 |
|
| 396 |
# make the dispatcher handle any outstanding stuff |
| 397 |
|
| 398 |
# create an IO watcher for each and every socket |
| 399 |
@snmp_watcher = ( |
| 400 |
(map { EV::io $_, EV::READ, sub { } } |
| 401 |
keys %{ $dispatcher->{_descriptors} }), |
| 402 |
); |
| 403 |
|
| 404 |
# if there are any timeouts, also create a timer |
| 405 |
push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { } |
| 406 |
if $event->[Net::SNMP::Dispatcher::_ACTIVE]; |
| 407 |
}; |
| 408 |
|
| 409 |
The callbacks are irrelevant, the only purpose of those watchers is |
| 410 |
to wake up the process as soon as one of those events occurs (socket |
| 411 |
readable, or timer timed out). The corresponding EV::check watcher will then |
| 412 |
clean up: |
| 413 |
|
| 414 |
our $snmp_check = EV::check sub { |
| 415 |
# destroy all watchers |
| 416 |
@snmp_watcher = (); |
| 417 |
|
| 418 |
# make the dispatcher handle any new stuff |
| 419 |
}; |
| 420 |
|
| 421 |
The callbacks of the created watchers will not be called as the watchers |
| 422 |
are destroyed before this cna happen (remember EV::check gets called |
| 423 |
first). |
| 424 |
|
| 425 |
The C<check_ns> variant doesn't start (activate) the newly created watcher. |
| 426 |
|
| 427 |
=back |
| 428 |
|
| 429 |
=head1 THREADS |
| 430 |
|
| 431 |
Threads are not supported by this in any way. Perl pseudo-threads is evil |
| 432 |
stuff and must die. |
| 433 |
|
| 434 |
=cut |
| 435 |
|
| 436 |
our $DIED = sub { |
| 437 |
warn "EV: error in callback (ignoring): $@"; |
| 438 |
}; |
| 439 |
|
| 440 |
init; |
| 441 |
|
| 442 |
push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"]; |
| 443 |
|
| 444 |
1; |
| 445 |
|
| 446 |
=head1 SEE ALSO |
| 447 |
|
| 448 |
L<EV::DNS>, L<EV::AnyEvent>. |
| 449 |
|
| 450 |
=head1 AUTHOR |
| 451 |
|
| 452 |
Marc Lehmann <schmorp@schmorp.de> |
| 453 |
http://home.schmorp.de/ |
| 454 |
|
| 455 |
=cut |
| 456 |
|
