| 1 |
=head1 NAME |
| 2 |
|
| 3 |
AnyEvent - provide framework for multiple event loops |
| 4 |
|
| 5 |
Event, Coro, Glib, Tk, Perl - various supported event loops |
| 6 |
|
| 7 |
=head1 SYNOPSIS |
| 8 |
|
| 9 |
use AnyEvent; |
| 10 |
|
| 11 |
my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
| 12 |
... |
| 13 |
}); |
| 14 |
|
| 15 |
my $w = AnyEvent->timer (after => $seconds, cb => sub { |
| 16 |
... |
| 17 |
}); |
| 18 |
|
| 19 |
my $w = AnyEvent->condvar; # stores wether a condition was flagged |
| 20 |
$w->wait; # enters "main loop" till $condvar gets ->broadcast |
| 21 |
$w->broadcast; # wake up current and all future wait's |
| 22 |
|
| 23 |
=head1 DESCRIPTION |
| 24 |
|
| 25 |
L<AnyEvent> provides an identical interface to multiple event loops. This |
| 26 |
allows module authors to utilise an event loop without forcing module |
| 27 |
users to use the same event loop (as only a single event loop can coexist |
| 28 |
peacefully at any one time). |
| 29 |
|
| 30 |
The interface itself is vaguely similar but not identical to the Event |
| 31 |
module. |
| 32 |
|
| 33 |
On the first call of any method, the module tries to detect the currently |
| 34 |
loaded event loop by probing wether any of the following modules is |
| 35 |
loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
| 36 |
used. If none is found, the module tries to load these modules in the |
| 37 |
order given. The first one that could be successfully loaded will be |
| 38 |
used. If still none could be found, AnyEvent will fall back to a pure-perl |
| 39 |
event loop, which is also not very efficient. |
| 40 |
|
| 41 |
Because AnyEvent first checks for modules that are already loaded, loading |
| 42 |
an Event model explicitly before first using AnyEvent will likely make |
| 43 |
that model the default. For example: |
| 44 |
|
| 45 |
use Tk; |
| 46 |
use AnyEvent; |
| 47 |
|
| 48 |
# .. AnyEvent will likely default to Tk |
| 49 |
|
| 50 |
The pure-perl implementation of AnyEvent is called |
| 51 |
C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
| 52 |
explicitly. |
| 53 |
|
| 54 |
=head1 WATCHERS |
| 55 |
|
| 56 |
AnyEvent has the central concept of a I<watcher>, which is an object that |
| 57 |
stores relevant data for each kind of event you are waiting for, such as |
| 58 |
the callback to call, the filehandle to watch, etc. |
| 59 |
|
| 60 |
These watchers are normal Perl objects with normal Perl lifetime. After |
| 61 |
creating a watcher it will immediately "watch" for events and invoke |
| 62 |
the callback. To disable the watcher you have to destroy it (e.g. by |
| 63 |
setting the variable that stores it to C<undef> or otherwise deleting all |
| 64 |
references to it). |
| 65 |
|
| 66 |
All watchers are created by calling a method on the C<AnyEvent> class. |
| 67 |
|
| 68 |
=head2 IO WATCHERS |
| 69 |
|
| 70 |
You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
| 71 |
the following mandatory arguments: |
| 72 |
|
| 73 |
C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
| 74 |
events. C<poll> must be a string that is either C<r> or C<w>, that creates |
| 75 |
a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback |
| 76 |
to invoke everytime the filehandle becomes ready. |
| 77 |
|
| 78 |
Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
| 79 |
a socket you can have one r + one w, not any more (limitation comes from |
| 80 |
Tk - if you are sure you are not using Tk this limitation is gone). |
| 81 |
|
| 82 |
Filehandles will be kept alive, so as long as the watcher exists, the |
| 83 |
filehandle exists, too. |
| 84 |
|
| 85 |
Example: |
| 86 |
|
| 87 |
# wait for readability of STDIN, then read a line and disable the watcher |
| 88 |
my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
| 89 |
chomp (my $input = <STDIN>); |
| 90 |
warn "read: $input\n"; |
| 91 |
undef $w; |
| 92 |
}); |
| 93 |
|
| 94 |
=head2 TIME WATCHERS |
| 95 |
|
| 96 |
You can create a time watcher by calling the C<< AnyEvent->timer >> |
| 97 |
method with the following mandatory arguments: |
| 98 |
|
| 99 |
C<after> after how many seconds (fractions are supported) should the timer |
| 100 |
activate. C<cb> the callback to invoke. |
| 101 |
|
| 102 |
The timer callback will be invoked at most once: if you want a repeating |
| 103 |
timer you have to create a new watcher (this is a limitation by both Tk |
| 104 |
and Glib). |
| 105 |
|
| 106 |
Example: |
| 107 |
|
| 108 |
# fire an event after 7.7 seconds |
| 109 |
my $w = AnyEvent->timer (after => 7.7, cb => sub { |
| 110 |
warn "timeout\n"; |
| 111 |
}); |
| 112 |
|
| 113 |
# to cancel the timer: |
| 114 |
undef $w |
| 115 |
|
| 116 |
=head2 CONDITION WATCHERS |
| 117 |
|
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Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
| 119 |
method without any arguments. |
| 120 |
|
| 121 |
A condition watcher watches for a condition - precisely that the C<< |
| 122 |
->broadcast >> method has been called. |
| 123 |
|
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The watcher has only two methods: |
| 125 |
|
| 126 |
=over 4 |
| 127 |
|
| 128 |
=item $cv->wait |
| 129 |
|
| 130 |
Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
| 131 |
called on c<$cv>, while servicing other watchers normally. |
| 132 |
|
| 133 |
Not all event models support a blocking wait - some die in that case, so |
| 134 |
if you are using this from a module, never require a blocking wait, but |
| 135 |
let the caller decide wether the call will block or not (for example, |
| 136 |
by coupling condition variables with some kind of request results and |
| 137 |
supporting callbacks so the caller knows that getting the result will not |
| 138 |
block, while still suppporting blockign waits if the caller so desires). |
| 139 |
|
| 140 |
You can only wait once on a condition - additional calls will return |
| 141 |
immediately. |
| 142 |
|
| 143 |
=item $cv->broadcast |
| 144 |
|
| 145 |
Flag the condition as ready - a running C<< ->wait >> and all further |
| 146 |
calls to C<wait> will return after this method has been called. If nobody |
| 147 |
is waiting the broadcast will be remembered.. |
| 148 |
|
| 149 |
Example: |
| 150 |
|
| 151 |
# wait till the result is ready |
| 152 |
my $result_ready = AnyEvent->condvar; |
| 153 |
|
| 154 |
# do something such as adding a timer |
| 155 |
# or socket watcher the calls $result_ready->broadcast |
| 156 |
# when the "result" is ready. |
| 157 |
|
| 158 |
$result_ready->wait; |
| 159 |
|
| 160 |
=back |
| 161 |
|
| 162 |
=head2 SIGNAL WATCHERS |
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|
| 164 |
You can listen for signals using a signal watcher, C<signal> is the signal |
| 165 |
I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
| 166 |
together into one callback invocation, and callbakc invocation might or |
| 167 |
might not be asynchronous. |
| 168 |
|
| 169 |
These watchers might use C<%SIG>, so programs overwriting those signals |
| 170 |
directly will likely not work correctly. |
| 171 |
|
| 172 |
Example: exit on SIGINT |
| 173 |
|
| 174 |
my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
| 175 |
|
| 176 |
=head2 CHILD PROCESS WATCHERS |
| 177 |
|
| 178 |
You can also listen for the status of a child process specified by the |
| 179 |
C<pid> argument. The watcher will only trigger once. This works by |
| 180 |
installing a signal handler for C<SIGCHLD>. |
| 181 |
|
| 182 |
Example: wait for pid 1333 |
| 183 |
|
| 184 |
my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
| 185 |
|
| 186 |
=head1 GLOBALS |
| 187 |
|
| 188 |
=over 4 |
| 189 |
|
| 190 |
=item $AnyEvent::MODEL |
| 191 |
|
| 192 |
Contains C<undef> until the first watcher is being created. Then it |
| 193 |
contains the event model that is being used, which is the name of the |
| 194 |
Perl class implementing the model. This class is usually one of the |
| 195 |
C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
| 196 |
AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
| 197 |
|
| 198 |
The known classes so far are: |
| 199 |
|
| 200 |
AnyEvent::Impl::Coro based on Coro::Event, best choise. |
| 201 |
AnyEvent::Impl::Event based on Event, also best choice :) |
| 202 |
AnyEvent::Impl::Glib based on Glib, second-best choice. |
| 203 |
AnyEvent::Impl::Tk based on Tk, very bad choice. |
| 204 |
AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
| 205 |
|
| 206 |
=item AnyEvent::detect |
| 207 |
|
| 208 |
Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
| 209 |
necessary. You should only call this function right before you would have |
| 210 |
created an AnyEvent watcher anyway, that is, very late at runtime. |
| 211 |
|
| 212 |
=back |
| 213 |
|
| 214 |
=head1 WHAT TO DO IN A MODULE |
| 215 |
|
| 216 |
As a module author, you should "use AnyEvent" and call AnyEvent methods |
| 217 |
freely, but you should not load a specific event module or rely on it. |
| 218 |
|
| 219 |
Be careful when you create watchers in the module body - Anyevent will |
| 220 |
decide which event module to use as soon as the first method is called, so |
| 221 |
by calling AnyEvent in your module body you force the user of your module |
| 222 |
to load the event module first. |
| 223 |
|
| 224 |
=head1 WHAT TO DO IN THE MAIN PROGRAM |
| 225 |
|
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There will always be a single main program - the only place that should |
| 227 |
dictate which event model to use. |
| 228 |
|
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If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
| 230 |
do anything special and let AnyEvent decide which implementation to chose. |
| 231 |
|
| 232 |
If the main program relies on a specific event model (for example, in Gtk2 |
| 233 |
programs you have to rely on either Glib or Glib::Event), you should load |
| 234 |
it before loading AnyEvent or any module that uses it, generally, as early |
| 235 |
as possible. The reason is that modules might create watchers when they |
| 236 |
are loaded, and AnyEvent will decide on the event model to use as soon as |
| 237 |
it creates watchers, and it might chose the wrong one unless you load the |
| 238 |
correct one yourself. |
| 239 |
|
| 240 |
You can chose to use a rather inefficient pure-perl implementation by |
| 241 |
loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
| 242 |
generally better. |
| 243 |
|
| 244 |
=cut |
| 245 |
|
| 246 |
package AnyEvent; |
| 247 |
|
| 248 |
no warnings; |
| 249 |
use strict; |
| 250 |
use Carp; |
| 251 |
|
| 252 |
our $VERSION = '2.5'; |
| 253 |
our $MODEL; |
| 254 |
|
| 255 |
our $AUTOLOAD; |
| 256 |
our @ISA; |
| 257 |
|
| 258 |
our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
| 259 |
|
| 260 |
our @REGISTRY; |
| 261 |
|
| 262 |
my @models = ( |
| 263 |
[Coro::Event:: => AnyEvent::Impl::Coro::], |
| 264 |
[Event:: => AnyEvent::Impl::Event::], |
| 265 |
[Glib:: => AnyEvent::Impl::Glib::], |
| 266 |
[Tk:: => AnyEvent::Impl::Tk::], |
| 267 |
[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
| 268 |
); |
| 269 |
|
| 270 |
our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
| 271 |
|
| 272 |
sub detect() { |
| 273 |
unless ($MODEL) { |
| 274 |
no strict 'refs'; |
| 275 |
|
| 276 |
# check for already loaded models |
| 277 |
for (@REGISTRY, @models) { |
| 278 |
my ($package, $model) = @$_; |
| 279 |
if (${"$package\::VERSION"} > 0) { |
| 280 |
if (eval "require $model") { |
| 281 |
$MODEL = $model; |
| 282 |
warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
| 283 |
last; |
| 284 |
} |
| 285 |
} |
| 286 |
} |
| 287 |
|
| 288 |
unless ($MODEL) { |
| 289 |
# try to load a model |
| 290 |
|
| 291 |
for (@REGISTRY, @models) { |
| 292 |
my ($package, $model) = @$_; |
| 293 |
if (eval "require $model") { |
| 294 |
$MODEL = $model; |
| 295 |
warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
| 296 |
last; |
| 297 |
} |
| 298 |
} |
| 299 |
|
| 300 |
$MODEL |
| 301 |
or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk."; |
| 302 |
} |
| 303 |
|
| 304 |
unshift @ISA, $MODEL; |
| 305 |
push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
| 306 |
} |
| 307 |
|
| 308 |
$MODEL |
| 309 |
} |
| 310 |
|
| 311 |
sub AUTOLOAD { |
| 312 |
(my $func = $AUTOLOAD) =~ s/.*://; |
| 313 |
|
| 314 |
$method{$func} |
| 315 |
or croak "$func: not a valid method for AnyEvent objects"; |
| 316 |
|
| 317 |
detect unless $MODEL; |
| 318 |
|
| 319 |
my $class = shift; |
| 320 |
$class->$func (@_); |
| 321 |
} |
| 322 |
|
| 323 |
package AnyEvent::Base; |
| 324 |
|
| 325 |
# default implementation for ->condvar, ->wait, ->broadcast |
| 326 |
|
| 327 |
sub condvar { |
| 328 |
bless \my $flag, "AnyEvent::Base::CondVar" |
| 329 |
} |
| 330 |
|
| 331 |
sub AnyEvent::Base::CondVar::broadcast { |
| 332 |
${$_[0]}++; |
| 333 |
} |
| 334 |
|
| 335 |
sub AnyEvent::Base::CondVar::wait { |
| 336 |
AnyEvent->one_event while !${$_[0]}; |
| 337 |
} |
| 338 |
|
| 339 |
# default implementation for ->signal |
| 340 |
|
| 341 |
our %SIG_CB; |
| 342 |
|
| 343 |
sub signal { |
| 344 |
my (undef, %arg) = @_; |
| 345 |
|
| 346 |
my $signal = uc $arg{signal} |
| 347 |
or Carp::croak "required option 'signal' is missing"; |
| 348 |
|
| 349 |
$SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
| 350 |
$SIG{$signal} ||= sub { |
| 351 |
$_->() for values %{ $SIG_CB{$signal} || {} }; |
| 352 |
}; |
| 353 |
|
| 354 |
bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
| 355 |
} |
| 356 |
|
| 357 |
sub AnyEvent::Base::Signal::DESTROY { |
| 358 |
my ($signal, $cb) = @{$_[0]}; |
| 359 |
|
| 360 |
delete $SIG_CB{$signal}{$cb}; |
| 361 |
|
| 362 |
$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
| 363 |
} |
| 364 |
|
| 365 |
# default implementation for ->child |
| 366 |
|
| 367 |
our %PID_CB; |
| 368 |
our $CHLD_W; |
| 369 |
our $PID_IDLE; |
| 370 |
our $WNOHANG; |
| 371 |
|
| 372 |
sub _child_wait { |
| 373 |
while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
| 374 |
$_->() for values %{ (delete $PID_CB{$pid}) || {} }; |
| 375 |
} |
| 376 |
|
| 377 |
undef $PID_IDLE; |
| 378 |
} |
| 379 |
|
| 380 |
sub child { |
| 381 |
my (undef, %arg) = @_; |
| 382 |
|
| 383 |
my $pid = uc $arg{pid} |
| 384 |
or Carp::croak "required option 'pid' is missing"; |
| 385 |
|
| 386 |
$PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
| 387 |
|
| 388 |
unless ($WNOHANG) { |
| 389 |
$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait); |
| 390 |
$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
| 391 |
} |
| 392 |
|
| 393 |
# child could be a zombie already |
| 394 |
$PID_IDLE ||= AnyEvent->timer (after => 0, cb => \&_child_wait); |
| 395 |
|
| 396 |
bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
| 397 |
} |
| 398 |
|
| 399 |
sub AnyEvent::Base::Child::DESTROY { |
| 400 |
my ($pid, $cb) = @{$_[0]}; |
| 401 |
|
| 402 |
delete $PID_CB{$pid}{$cb}; |
| 403 |
delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
| 404 |
|
| 405 |
undef $CHLD_W unless keys %PID_CB; |
| 406 |
} |
| 407 |
|
| 408 |
=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
| 409 |
|
| 410 |
If you need to support another event library which isn't directly |
| 411 |
supported by AnyEvent, you can supply your own interface to it by |
| 412 |
pushing, before the first watcher gets created, the package name of |
| 413 |
the event module and the package name of the interface to use onto |
| 414 |
C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
| 415 |
AnyEvent. |
| 416 |
|
| 417 |
Example: |
| 418 |
|
| 419 |
push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
| 420 |
|
| 421 |
This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
| 422 |
package/class when it finds the C<urxvt> package/module is loaded. When |
| 423 |
AnyEvent is loaded and asked to find a suitable event model, it will |
| 424 |
first check for the presence of urxvt. |
| 425 |
|
| 426 |
The class should provide implementations for all watcher types (see |
| 427 |
L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
| 428 |
(Source code) and so on for actual examples, use C<perldoc -m |
| 429 |
AnyEvent::Impl::Glib> to see the sources). |
| 430 |
|
| 431 |
The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
| 432 |
uses the above line as-is. An interface isn't included in AnyEvent |
| 433 |
because it doesn't make sense outside the embedded interpreter inside |
| 434 |
I<rxvt-unicode>, and it is updated and maintained as part of the |
| 435 |
I<rxvt-unicode> distribution. |
| 436 |
|
| 437 |
I<rxvt-unicode> also cheats a bit by not providing blocking access to |
| 438 |
condition variables: code blocking while waiting for a condition will |
| 439 |
C<die>. This still works with most modules/usages, and blocking calls must |
| 440 |
not be in an interactive appliation, so it makes sense. |
| 441 |
|
| 442 |
=head1 ENVIRONMENT VARIABLES |
| 443 |
|
| 444 |
The following environment variables are used by this module: |
| 445 |
|
| 446 |
C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
| 447 |
model gets used. |
| 448 |
|
| 449 |
=head1 EXAMPLE |
| 450 |
|
| 451 |
The following program uses an io watcher to read data from stdin, a timer |
| 452 |
to display a message once per second, and a condvar to exit the program |
| 453 |
when the user enters quit: |
| 454 |
|
| 455 |
use AnyEvent; |
| 456 |
|
| 457 |
my $cv = AnyEvent->condvar; |
| 458 |
|
| 459 |
my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
| 460 |
warn "io event <$_[0]>\n"; # will always output <r> |
| 461 |
chomp (my $input = <STDIN>); # read a line |
| 462 |
warn "read: $input\n"; # output what has been read |
| 463 |
$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
| 464 |
}); |
| 465 |
|
| 466 |
my $time_watcher; # can only be used once |
| 467 |
|
| 468 |
sub new_timer { |
| 469 |
$timer = AnyEvent->timer (after => 1, cb => sub { |
| 470 |
warn "timeout\n"; # print 'timeout' about every second |
| 471 |
&new_timer; # and restart the time |
| 472 |
}); |
| 473 |
} |
| 474 |
|
| 475 |
new_timer; # create first timer |
| 476 |
|
| 477 |
$cv->wait; # wait until user enters /^q/i |
| 478 |
|
| 479 |
=head1 REAL-WORLD EXAMPLE |
| 480 |
|
| 481 |
Consider the L<Net::FCP> module. It features (among others) the following |
| 482 |
API calls, which are to freenet what HTTP GET requests are to http: |
| 483 |
|
| 484 |
my $data = $fcp->client_get ($url); # blocks |
| 485 |
|
| 486 |
my $transaction = $fcp->txn_client_get ($url); # does not block |
| 487 |
$transaction->cb ( sub { ... } ); # set optional result callback |
| 488 |
my $data = $transaction->result; # possibly blocks |
| 489 |
|
| 490 |
The C<client_get> method works like C<LWP::Simple::get>: it requests the |
| 491 |
given URL and waits till the data has arrived. It is defined to be: |
| 492 |
|
| 493 |
sub client_get { $_[0]->txn_client_get ($_[1])->result } |
| 494 |
|
| 495 |
And in fact is automatically generated. This is the blocking API of |
| 496 |
L<Net::FCP>, and it works as simple as in any other, similar, module. |
| 497 |
|
| 498 |
More complicated is C<txn_client_get>: It only creates a transaction |
| 499 |
(completion, result, ...) object and initiates the transaction. |
| 500 |
|
| 501 |
my $txn = bless { }, Net::FCP::Txn::; |
| 502 |
|
| 503 |
It also creates a condition variable that is used to signal the completion |
| 504 |
of the request: |
| 505 |
|
| 506 |
$txn->{finished} = AnyAvent->condvar; |
| 507 |
|
| 508 |
It then creates a socket in non-blocking mode. |
| 509 |
|
| 510 |
socket $txn->{fh}, ...; |
| 511 |
fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
| 512 |
connect $txn->{fh}, ... |
| 513 |
and !$!{EWOULDBLOCK} |
| 514 |
and !$!{EINPROGRESS} |
| 515 |
and Carp::croak "unable to connect: $!\n"; |
| 516 |
|
| 517 |
Then it creates a write-watcher which gets called whenever an error occurs |
| 518 |
or the connection succeeds: |
| 519 |
|
| 520 |
$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
| 521 |
|
| 522 |
And returns this transaction object. The C<fh_ready_w> callback gets |
| 523 |
called as soon as the event loop detects that the socket is ready for |
| 524 |
writing. |
| 525 |
|
| 526 |
The C<fh_ready_w> method makes the socket blocking again, writes the |
| 527 |
request data and replaces the watcher by a read watcher (waiting for reply |
| 528 |
data). The actual code is more complicated, but that doesn't matter for |
| 529 |
this example: |
| 530 |
|
| 531 |
fcntl $txn->{fh}, F_SETFL, 0; |
| 532 |
syswrite $txn->{fh}, $txn->{request} |
| 533 |
or die "connection or write error"; |
| 534 |
$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
| 535 |
|
| 536 |
Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
| 537 |
result and signals any possible waiters that the request ahs finished: |
| 538 |
|
| 539 |
sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
| 540 |
|
| 541 |
if (end-of-file or data complete) { |
| 542 |
$txn->{result} = $txn->{buf}; |
| 543 |
$txn->{finished}->broadcast; |
| 544 |
$txb->{cb}->($txn) of $txn->{cb}; # also call callback |
| 545 |
} |
| 546 |
|
| 547 |
The C<result> method, finally, just waits for the finished signal (if the |
| 548 |
request was already finished, it doesn't wait, of course, and returns the |
| 549 |
data: |
| 550 |
|
| 551 |
$txn->{finished}->wait; |
| 552 |
return $txn->{result}; |
| 553 |
|
| 554 |
The actual code goes further and collects all errors (C<die>s, exceptions) |
| 555 |
that occured during request processing. The C<result> method detects |
| 556 |
wether an exception as thrown (it is stored inside the $txn object) |
| 557 |
and just throws the exception, which means connection errors and other |
| 558 |
problems get reported tot he code that tries to use the result, not in a |
| 559 |
random callback. |
| 560 |
|
| 561 |
All of this enables the following usage styles: |
| 562 |
|
| 563 |
1. Blocking: |
| 564 |
|
| 565 |
my $data = $fcp->client_get ($url); |
| 566 |
|
| 567 |
2. Blocking, but parallelizing: |
| 568 |
|
| 569 |
my @datas = map $_->result, |
| 570 |
map $fcp->txn_client_get ($_), |
| 571 |
@urls; |
| 572 |
|
| 573 |
Both blocking examples work without the module user having to know |
| 574 |
anything about events. |
| 575 |
|
| 576 |
3a. Event-based in a main program, using any support Event module: |
| 577 |
|
| 578 |
use Event; |
| 579 |
|
| 580 |
$fcp->txn_client_get ($url)->cb (sub { |
| 581 |
my $txn = shift; |
| 582 |
my $data = $txn->result; |
| 583 |
... |
| 584 |
}); |
| 585 |
|
| 586 |
Event::loop; |
| 587 |
|
| 588 |
3b. The module user could use AnyEvent, too: |
| 589 |
|
| 590 |
use AnyEvent; |
| 591 |
|
| 592 |
my $quit = AnyEvent->condvar; |
| 593 |
|
| 594 |
$fcp->txn_client_get ($url)->cb (sub { |
| 595 |
... |
| 596 |
$quit->broadcast; |
| 597 |
}); |
| 598 |
|
| 599 |
$quit->wait; |
| 600 |
|
| 601 |
=head1 SEE ALSO |
| 602 |
|
| 603 |
Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
| 604 |
|
| 605 |
Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
| 606 |
|
| 607 |
Nontrivial usage example: L<Net::FCP>. |
| 608 |
|
| 609 |
=head1 |
| 610 |
|
| 611 |
=cut |
| 612 |
|
| 613 |
1 |
| 614 |
|
