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Revision 1.282 by root, Tue Aug 11 01:18:27 2009 UTC vs.
Revision 1.329 by root, Sun Jul 11 05:44:22 2010 UTC

7 7
8=head1 SYNOPSIS 8=head1 SYNOPSIS
9 9
10 use AnyEvent; 10 use AnyEvent;
11 11
12 # if you prefer function calls, look at the AE manpage for
13 # an alternative API.
14
12 # file descriptor readable 15 # file handle or descriptor readable
13 my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); 16 my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
14 17
15 # one-shot or repeating timers 18 # one-shot or repeating timers
16 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); 19 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
17 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... 20 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
135 use AnyEvent; 138 use AnyEvent;
136 139
137 # .. AnyEvent will likely default to Tk 140 # .. AnyEvent will likely default to Tk
138 141
139The I<likely> means that, if any module loads another event model and 142The I<likely> means that, if any module loads another event model and
140starts using it, all bets are off. Maybe you should tell their authors to 143starts using it, all bets are off - this case should be very rare though,
141use AnyEvent so their modules work together with others seamlessly... 144as very few modules hardcode event loops without announcing this very
145loudly.
142 146
143The pure-perl implementation of AnyEvent is called 147The pure-perl implementation of AnyEvent is called
144C<AnyEvent::Impl::Perl>. Like other event modules you can load it 148C<AnyEvent::Impl::Perl>. Like other event modules you can load it
145explicitly and enjoy the high availability of that event loop :) 149explicitly and enjoy the high availability of that event loop :)
146 150
363might affect timers and time-outs. 367might affect timers and time-outs.
364 368
365When this is the case, you can call this method, which will update the 369When this is the case, you can call this method, which will update the
366event loop's idea of "current time". 370event loop's idea of "current time".
367 371
372A typical example would be a script in a web server (e.g. C<mod_perl>) -
373when mod_perl executes the script, then the event loop will have the wrong
374idea about the "current time" (being potentially far in the past, when the
375script ran the last time). In that case you should arrange a call to C<<
376AnyEvent->now_update >> each time the web server process wakes up again
377(e.g. at the start of your script, or in a handler).
378
368Note that updating the time I<might> cause some events to be handled. 379Note that updating the time I<might> cause some events to be handled.
369 380
370=back 381=back
371 382
372=head2 SIGNAL WATCHERS 383=head2 SIGNAL WATCHERS
395correctly. 406correctly.
396 407
397Example: exit on SIGINT 408Example: exit on SIGINT
398 409
399 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); 410 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
411
412=head3 Restart Behaviour
413
414While restart behaviour is up to the event loop implementation, most will
415not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
416pure perl implementation).
417
418=head3 Safe/Unsafe Signals
419
420Perl signals can be either "safe" (synchronous to opcode handling) or
421"unsafe" (asynchronous) - the former might get delayed indefinitely, the
422latter might corrupt your memory.
423
424AnyEvent signal handlers are, in addition, synchronous to the event loop,
425i.e. they will not interrupt your running perl program but will only be
426called as part of the normal event handling (just like timer, I/O etc.
427callbacks, too).
400 428
401=head3 Signal Races, Delays and Workarounds 429=head3 Signal Races, Delays and Workarounds
402 430
403Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching 431Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
404callbacks to signals in a generic way, which is a pity, as you cannot 432callbacks to signals in a generic way, which is a pity, as you cannot
479 507
480=head2 IDLE WATCHERS 508=head2 IDLE WATCHERS
481 509
482 $w = AnyEvent->idle (cb => <callback>); 510 $w = AnyEvent->idle (cb => <callback>);
483 511
484Sometimes there is a need to do something, but it is not so important 512Repeatedly invoke the callback after the process becomes idle, until
485to do it instantly, but only when there is nothing better to do. This 513either the watcher is destroyed or new events have been detected.
486"nothing better to do" is usually defined to be "no other events need
487attention by the event loop".
488 514
489Idle watchers ideally get invoked when the event loop has nothing 515Idle watchers are useful when there is a need to do something, but it
490better to do, just before it would block the process to wait for new 516is not so important (or wise) to do it instantly. The callback will be
491events. Instead of blocking, the idle watcher is invoked. 517invoked only when there is "nothing better to do", which is usually
518defined as "all outstanding events have been handled and no new events
519have been detected". That means that idle watchers ideally get invoked
520when the event loop has just polled for new events but none have been
521detected. Instead of blocking to wait for more events, the idle watchers
522will be invoked.
492 523
493Most event loops unfortunately do not really support idle watchers (only 524Unfortunately, most event loops do not really support idle watchers (only
494EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent 525EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
495will simply call the callback "from time to time". 526will simply call the callback "from time to time".
496 527
497Example: read lines from STDIN, but only process them when the 528Example: read lines from STDIN, but only process them when the
498program is otherwise idle: 529program is otherwise idle:
526will actively watch for new events and call your callbacks. 557will actively watch for new events and call your callbacks.
527 558
528AnyEvent is slightly different: it expects somebody else to run the event 559AnyEvent is slightly different: it expects somebody else to run the event
529loop and will only block when necessary (usually when told by the user). 560loop and will only block when necessary (usually when told by the user).
530 561
531The instrument to do that is called a "condition variable", so called 562The tool to do that is called a "condition variable", so called because
532because they represent a condition that must become true. 563they represent a condition that must become true.
533 564
534Now is probably a good time to look at the examples further below. 565Now is probably a good time to look at the examples further below.
535 566
536Condition variables can be created by calling the C<< AnyEvent->condvar 567Condition variables can be created by calling the C<< AnyEvent->condvar
537>> method, usually without arguments. The only argument pair allowed is 568>> method, usually without arguments. The only argument pair allowed is
542After creation, the condition variable is "false" until it becomes "true" 573After creation, the condition variable is "false" until it becomes "true"
543by calling the C<send> method (or calling the condition variable as if it 574by calling the C<send> method (or calling the condition variable as if it
544were a callback, read about the caveats in the description for the C<< 575were a callback, read about the caveats in the description for the C<<
545->send >> method). 576->send >> method).
546 577
547Condition variables are similar to callbacks, except that you can 578Since condition variables are the most complex part of the AnyEvent API, here are
548optionally wait for them. They can also be called merge points - points 579some different mental models of what they are - pick the ones you can connect to:
549in time where multiple outstanding events have been processed. And yet 580
550another way to call them is transactions - each condition variable can be 581=over 4
551used to represent a transaction, which finishes at some point and delivers 582
552a result. And yet some people know them as "futures" - a promise to 583=item * Condition variables are like callbacks - you can call them (and pass them instead
553compute/deliver something that you can wait for. 584of callbacks). Unlike callbacks however, you can also wait for them to be called.
585
586=item * Condition variables are signals - one side can emit or send them,
587the other side can wait for them, or install a handler that is called when
588the signal fires.
589
590=item * Condition variables are like "Merge Points" - points in your program
591where you merge multiple independent results/control flows into one.
592
593=item * Condition variables represent a transaction - function that start
594some kind of transaction can return them, leaving the caller the choice
595between waiting in a blocking fashion, or setting a callback.
596
597=item * Condition variables represent future values, or promises to deliver
598some result, long before the result is available.
599
600=back
554 601
555Condition variables are very useful to signal that something has finished, 602Condition variables are very useful to signal that something has finished,
556for example, if you write a module that does asynchronous http requests, 603for example, if you write a module that does asynchronous http requests,
557then a condition variable would be the ideal candidate to signal the 604then a condition variable would be the ideal candidate to signal the
558availability of results. The user can either act when the callback is 605availability of results. The user can either act when the callback is
579eventually calls C<< -> send >>, and the "consumer side", which waits 626eventually calls C<< -> send >>, and the "consumer side", which waits
580for the send to occur. 627for the send to occur.
581 628
582Example: wait for a timer. 629Example: wait for a timer.
583 630
584 # wait till the result is ready 631 # condition: "wait till the timer is fired"
585 my $result_ready = AnyEvent->condvar; 632 my $timer_fired = AnyEvent->condvar;
586 633
587 # do something such as adding a timer 634 # create the timer - we could wait for, say
588 # or socket watcher the calls $result_ready->send 635 # a handle becomign ready, or even an
589 # when the "result" is ready. 636 # AnyEvent::HTTP request to finish, but
590 # in this case, we simply use a timer: 637 # in this case, we simply use a timer:
591 my $w = AnyEvent->timer ( 638 my $w = AnyEvent->timer (
592 after => 1, 639 after => 1,
593 cb => sub { $result_ready->send }, 640 cb => sub { $timer_fired->send },
594 ); 641 );
595 642
596 # this "blocks" (while handling events) till the callback 643 # this "blocks" (while handling events) till the callback
597 # calls -<send 644 # calls ->send
598 $result_ready->recv; 645 $timer_fired->recv;
599 646
600Example: wait for a timer, but take advantage of the fact that condition 647Example: wait for a timer, but take advantage of the fact that condition
601variables are also callable directly. 648variables are also callable directly.
602 649
603 my $done = AnyEvent->condvar; 650 my $done = AnyEvent->condvar;
942You should check C<$AnyEvent::MODEL> before adding to this array, though: 989You should check C<$AnyEvent::MODEL> before adding to this array, though:
943if it is defined then the event loop has already been detected, and the 990if it is defined then the event loop has already been detected, and the
944array will be ignored. 991array will be ignored.
945 992
946Best use C<AnyEvent::post_detect { BLOCK }> when your application allows 993Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
947it,as it takes care of these details. 994it, as it takes care of these details.
948 995
949This variable is mainly useful for modules that can do something useful 996This variable is mainly useful for modules that can do something useful
950when AnyEvent is used and thus want to know when it is initialised, but do 997when AnyEvent is used and thus want to know when it is initialised, but do
951not need to even load it by default. This array provides the means to hook 998not need to even load it by default. This array provides the means to hook
952into AnyEvent passively, without loading it. 999into AnyEvent passively, without loading it.
1000
1001Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
1002together, you could put this into Coro (this is the actual code used by
1003Coro to accomplish this):
1004
1005 if (defined $AnyEvent::MODEL) {
1006 # AnyEvent already initialised, so load Coro::AnyEvent
1007 require Coro::AnyEvent;
1008 } else {
1009 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
1010 # as soon as it is
1011 push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
1012 }
953 1013
954=back 1014=back
955 1015
956=head1 WHAT TO DO IN A MODULE 1016=head1 WHAT TO DO IN A MODULE
957 1017
1014=head1 OTHER MODULES 1074=head1 OTHER MODULES
1015 1075
1016The following is a non-exhaustive list of additional modules that use 1076The following is a non-exhaustive list of additional modules that use
1017AnyEvent as a client and can therefore be mixed easily with other AnyEvent 1077AnyEvent as a client and can therefore be mixed easily with other AnyEvent
1018modules and other event loops in the same program. Some of the modules 1078modules and other event loops in the same program. Some of the modules
1019come with AnyEvent, most are available via CPAN. 1079come as part of AnyEvent, the others are available via CPAN.
1020 1080
1021=over 4 1081=over 4
1022 1082
1023=item L<AnyEvent::Util> 1083=item L<AnyEvent::Util>
1024 1084
1039 1099
1040=item L<AnyEvent::DNS> 1100=item L<AnyEvent::DNS>
1041 1101
1042Provides rich asynchronous DNS resolver capabilities. 1102Provides rich asynchronous DNS resolver capabilities.
1043 1103
1104=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
1105
1106Implement event-based interfaces to the protocols of the same name (for
1107the curious, IGS is the International Go Server and FCP is the Freenet
1108Client Protocol).
1109
1110=item L<AnyEvent::Handle::UDP>
1111
1112Here be danger!
1113
1114As Pauli would put it, "Not only is it not right, it's not even wrong!" -
1115there are so many things wrong with AnyEvent::Handle::UDP, most notably
1116it's use of a stream-based API with a protocol that isn't streamable, that
1117the only way to improve it is to delete it.
1118
1119It features data corruption (but typically only under load) and general
1120confusion. On top, the author is not only clueless about UDP but also
1121fact-resistant - some gems of his understanding: "connect doesn't work
1122with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
1123packets", "I don't need to implement proper error checking as UDP doesn't
1124support error checking" and so on - he doesn't even understand what's
1125wrong with his module when it is explained to him.
1126
1044=item L<AnyEvent::HTTP> 1127=item L<AnyEvent::DBI>
1045 1128
1046A simple-to-use HTTP library that is capable of making a lot of concurrent 1129Executes L<DBI> requests asynchronously in a proxy process for you,
1047HTTP requests. 1130notifying you in an event-bnased way when the operation is finished.
1131
1132=item L<AnyEvent::AIO>
1133
1134Truly asynchronous (as opposed to non-blocking) I/O, should be in the
1135toolbox of every event programmer. AnyEvent::AIO transparently fuses
1136L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
1137file I/O, and much more.
1048 1138
1049=item L<AnyEvent::HTTPD> 1139=item L<AnyEvent::HTTPD>
1050 1140
1051Provides a simple web application server framework. 1141A simple embedded webserver.
1052 1142
1053=item L<AnyEvent::FastPing> 1143=item L<AnyEvent::FastPing>
1054 1144
1055The fastest ping in the west. 1145The fastest ping in the west.
1056
1057=item L<AnyEvent::DBI>
1058
1059Executes L<DBI> requests asynchronously in a proxy process.
1060
1061=item L<AnyEvent::AIO>
1062
1063Truly asynchronous I/O, should be in the toolbox of every event
1064programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
1065together.
1066
1067=item L<AnyEvent::BDB>
1068
1069Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
1070L<BDB> and AnyEvent together.
1071
1072=item L<AnyEvent::GPSD>
1073
1074A non-blocking interface to gpsd, a daemon delivering GPS information.
1075
1076=item L<AnyEvent::IRC>
1077
1078AnyEvent based IRC client module family (replacing the older Net::IRC3).
1079
1080=item L<AnyEvent::XMPP>
1081
1082AnyEvent based XMPP (Jabber protocol) module family (replacing the older
1083Net::XMPP2>.
1084
1085=item L<AnyEvent::IGS>
1086
1087A non-blocking interface to the Internet Go Server protocol (used by
1088L<App::IGS>).
1089
1090=item L<Net::FCP>
1091
1092AnyEvent-based implementation of the Freenet Client Protocol, birthplace
1093of AnyEvent.
1094
1095=item L<Event::ExecFlow>
1096
1097High level API for event-based execution flow control.
1098 1146
1099=item L<Coro> 1147=item L<Coro>
1100 1148
1101Has special support for AnyEvent via L<Coro::AnyEvent>. 1149Has special support for AnyEvent via L<Coro::AnyEvent>.
1102 1150
1106 1154
1107package AnyEvent; 1155package AnyEvent;
1108 1156
1109# basically a tuned-down version of common::sense 1157# basically a tuned-down version of common::sense
1110sub common_sense { 1158sub common_sense {
1111 # no warnings 1159 # from common:.sense 1.0
1112 ${^WARNING_BITS} ^= ${^WARNING_BITS}; 1160 ${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x00";
1113 # use strict vars subs 1161 # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
1114 $^H |= 0x00000600; 1162 $^H |= 0x00000600;
1115} 1163}
1116 1164
1117BEGIN { AnyEvent::common_sense } 1165BEGIN { AnyEvent::common_sense }
1118 1166
1119use Carp (); 1167use Carp ();
1120 1168
1121our $VERSION = '5.1'; 1169our $VERSION = '5.271';
1122our $MODEL; 1170our $MODEL;
1123 1171
1124our $AUTOLOAD; 1172our $AUTOLOAD;
1125our @ISA; 1173our @ISA;
1126 1174
1127our @REGISTRY; 1175our @REGISTRY;
1128 1176
1129our $WIN32;
1130
1131our $VERBOSE; 1177our $VERBOSE;
1132 1178
1133BEGIN { 1179BEGIN {
1134 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }"; 1180 require "AnyEvent/constants.pl";
1181
1135 eval "sub TAINT(){ " . (${^TAINT}*1) . " }"; 1182 eval "sub TAINT (){" . (${^TAINT}*1) . "}";
1136 1183
1137 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} 1184 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1138 if ${^TAINT}; 1185 if ${^TAINT};
1139 1186
1140 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1; 1187 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
1183our @post_detect; 1230our @post_detect;
1184 1231
1185sub post_detect(&) { 1232sub post_detect(&) {
1186 my ($cb) = @_; 1233 my ($cb) = @_;
1187 1234
1188 if ($MODEL) {
1189 $cb->();
1190
1191 undef
1192 } else {
1193 push @post_detect, $cb; 1235 push @post_detect, $cb;
1194 1236
1195 defined wantarray 1237 defined wantarray
1196 ? bless \$cb, "AnyEvent::Util::postdetect" 1238 ? bless \$cb, "AnyEvent::Util::postdetect"
1197 : () 1239 : ()
1198 }
1199} 1240}
1200 1241
1201sub AnyEvent::Util::postdetect::DESTROY { 1242sub AnyEvent::Util::postdetect::DESTROY {
1202 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1243 @post_detect = grep $_ != ${$_[0]}, @post_detect;
1203} 1244}
1204 1245
1205sub detect() { 1246sub detect() {
1247 # free some memory
1248 *detect = sub () { $MODEL };
1249
1250 local $!; # for good measure
1251 local $SIG{__DIE__};
1252
1253 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1254 my $model = "AnyEvent::Impl::$1";
1255 if (eval "require $model") {
1256 $MODEL = $model;
1257 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1258 } else {
1259 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1260 }
1261 }
1262
1263 # check for already loaded models
1206 unless ($MODEL) { 1264 unless ($MODEL) {
1207 local $SIG{__DIE__}; 1265 for (@REGISTRY, @models) {
1208 1266 my ($package, $model) = @$_;
1209 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 1267 if (${"$package\::VERSION"} > 0) {
1210 my $model = "AnyEvent::Impl::$1";
1211 if (eval "require $model") { 1268 if (eval "require $model") {
1212 $MODEL = $model; 1269 $MODEL = $model;
1213 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2; 1270 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1214 } else { 1271 last;
1215 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE; 1272 }
1216 } 1273 }
1217 } 1274 }
1218 1275
1219 # check for already loaded models
1220 unless ($MODEL) { 1276 unless ($MODEL) {
1277 # try to autoload a model
1221 for (@REGISTRY, @models) { 1278 for (@REGISTRY, @models) {
1222 my ($package, $model) = @$_; 1279 my ($package, $model, $autoload) = @$_;
1280 if (
1281 $autoload
1282 and eval "require $package"
1223 if (${"$package\::VERSION"} > 0) { 1283 and ${"$package\::VERSION"} > 0
1224 if (eval "require $model") { 1284 and eval "require $model"
1285 ) {
1225 $MODEL = $model; 1286 $MODEL = $model;
1226 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2; 1287 warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1227 last; 1288 last;
1228 }
1229 } 1289 }
1230 } 1290 }
1231 1291
1232 unless ($MODEL) {
1233 # try to autoload a model
1234 for (@REGISTRY, @models) {
1235 my ($package, $model, $autoload) = @$_;
1236 if (
1237 $autoload
1238 and eval "require $package"
1239 and ${"$package\::VERSION"} > 0
1240 and eval "require $model"
1241 ) {
1242 $MODEL = $model;
1243 warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1244 last;
1245 }
1246 }
1247
1248 $MODEL 1292 $MODEL
1249 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n"; 1293 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
1250 }
1251 } 1294 }
1252
1253 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1254
1255 unshift @ISA, $MODEL;
1256
1257 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1258
1259 (shift @post_detect)->() while @post_detect;
1260 } 1295 }
1296
1297 @models = (); # free probe data
1298
1299 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1300 unshift @ISA, $MODEL;
1301
1302 # now nuke some methods that are overriden by the backend.
1303 # SUPER is not allowed.
1304 for (qw(time signal child idle)) {
1305 undef &{"AnyEvent::Base::$_"}
1306 if defined &{"$MODEL\::$_"};
1307 }
1308
1309 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1310
1311 (shift @post_detect)->() while @post_detect;
1312
1313 *post_detect = sub(&) {
1314 shift->();
1315
1316 undef
1317 };
1261 1318
1262 $MODEL 1319 $MODEL
1263} 1320}
1264 1321
1265sub AUTOLOAD { 1322sub AUTOLOAD {
1266 (my $func = $AUTOLOAD) =~ s/.*://; 1323 (my $func = $AUTOLOAD) =~ s/.*://;
1267 1324
1268 $method{$func} 1325 $method{$func}
1269 or Carp::croak "$func: not a valid method for AnyEvent objects"; 1326 or Carp::croak "$func: not a valid AnyEvent class method";
1270 1327
1271 detect unless $MODEL; 1328 detect;
1272 1329
1273 my $class = shift; 1330 my $class = shift;
1274 $class->$func (@_); 1331 $class->$func (@_);
1275} 1332}
1276 1333
1293 1350
1294=head1 SIMPLIFIED AE API 1351=head1 SIMPLIFIED AE API
1295 1352
1296Starting with version 5.0, AnyEvent officially supports a second, much 1353Starting with version 5.0, AnyEvent officially supports a second, much
1297simpler, API that is designed to reduce the calling, typing and memory 1354simpler, API that is designed to reduce the calling, typing and memory
1298overhead. 1355overhead by using function call syntax and a fixed number of parameters.
1299 1356
1300See the L<AE> manpage for details. 1357See the L<AE> manpage for details.
1301 1358
1302=cut 1359=cut
1303 1360
1304package AE; 1361package AE;
1305 1362
1306our $VERSION = $AnyEvent::VERSION; 1363our $VERSION = $AnyEvent::VERSION;
1364
1365# fall back to the main API by default - backends and AnyEvent::Base
1366# implementations can overwrite these.
1307 1367
1308sub io($$$) { 1368sub io($$$) {
1309 AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2]) 1369 AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
1310} 1370}
1311 1371
1343 1403
1344package AnyEvent::Base; 1404package AnyEvent::Base;
1345 1405
1346# default implementations for many methods 1406# default implementations for many methods
1347 1407
1348sub _time { 1408sub time {
1409 eval q{ # poor man's autoloading {}
1349 # probe for availability of Time::HiRes 1410 # probe for availability of Time::HiRes
1350 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { 1411 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1351 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8; 1412 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1352 *_time = \&Time::HiRes::time; 1413 *AE::time = \&Time::HiRes::time;
1353 # if (eval "use POSIX (); (POSIX::times())... 1414 # if (eval "use POSIX (); (POSIX::times())...
1354 } else { 1415 } else {
1355 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE; 1416 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1356 *_time = sub { time }; # epic fail 1417 *AE::time = sub (){ time }; # epic fail
1418 }
1419
1420 *time = sub { AE::time }; # different prototypes
1357 } 1421 };
1422 die if $@;
1358 1423
1359 &_time 1424 &time
1360} 1425}
1361 1426
1362sub time { _time } 1427*now = \&time;
1363sub now { _time } 1428
1364sub now_update { } 1429sub now_update { }
1365 1430
1366# default implementation for ->condvar 1431# default implementation for ->condvar
1367 1432
1368sub condvar { 1433sub condvar {
1434 eval q{ # poor man's autoloading {}
1435 *condvar = sub {
1369 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" 1436 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1437 };
1438
1439 *AE::cv = sub (;&) {
1440 bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
1441 };
1442 };
1443 die if $@;
1444
1445 &condvar
1370} 1446}
1371 1447
1372# default implementation for ->signal 1448# default implementation for ->signal
1373 1449
1374our $HAVE_ASYNC_INTERRUPT; 1450our $HAVE_ASYNC_INTERRUPT;
1375 1451
1376sub _have_async_interrupt() { 1452sub _have_async_interrupt() {
1377 $HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} 1453 $HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
1378 && eval "use Async::Interrupt 1.0 (); 1") 1454 && eval "use Async::Interrupt 1.02 (); 1")
1379 unless defined $HAVE_ASYNC_INTERRUPT; 1455 unless defined $HAVE_ASYNC_INTERRUPT;
1380 1456
1381 $HAVE_ASYNC_INTERRUPT 1457 $HAVE_ASYNC_INTERRUPT
1382} 1458}
1383 1459
1384our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); 1460our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1385our (%SIG_ASY, %SIG_ASY_W); 1461our (%SIG_ASY, %SIG_ASY_W);
1386our ($SIG_COUNT, $SIG_TW); 1462our ($SIG_COUNT, $SIG_TW);
1387 1463
1388sub _signal_exec {
1389 $HAVE_ASYNC_INTERRUPT
1390 ? $SIGPIPE_R->drain
1391 : sysread $SIGPIPE_R, my $dummy, 9;
1392
1393 while (%SIG_EV) {
1394 for (keys %SIG_EV) {
1395 delete $SIG_EV{$_};
1396 $_->() for values %{ $SIG_CB{$_} || {} };
1397 }
1398 }
1399}
1400
1401# install a dummy wakeup watcher to reduce signal catching latency 1464# install a dummy wakeup watcher to reduce signal catching latency
1465# used by Impls
1402sub _sig_add() { 1466sub _sig_add() {
1403 unless ($SIG_COUNT++) { 1467 unless ($SIG_COUNT++) {
1404 # try to align timer on a full-second boundary, if possible 1468 # try to align timer on a full-second boundary, if possible
1405 my $NOW = AE::now; 1469 my $NOW = AE::now;
1406 1470
1416 undef $SIG_TW 1480 undef $SIG_TW
1417 unless --$SIG_COUNT; 1481 unless --$SIG_COUNT;
1418} 1482}
1419 1483
1420our $_sig_name_init; $_sig_name_init = sub { 1484our $_sig_name_init; $_sig_name_init = sub {
1421 eval q{ # poor man's autoloading 1485 eval q{ # poor man's autoloading {}
1422 undef $_sig_name_init; 1486 undef $_sig_name_init;
1423 1487
1424 if (_have_async_interrupt) { 1488 if (_have_async_interrupt) {
1425 *sig2num = \&Async::Interrupt::sig2num; 1489 *sig2num = \&Async::Interrupt::sig2num;
1426 *sig2name = \&Async::Interrupt::sig2name; 1490 *sig2name = \&Async::Interrupt::sig2name;
1458 $SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec; 1522 $SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1459 1523
1460 } else { 1524 } else {
1461 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8; 1525 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1462 1526
1463 require Fcntl;
1464
1465 if (AnyEvent::WIN32) { 1527 if (AnyEvent::WIN32) {
1466 require AnyEvent::Util; 1528 require AnyEvent::Util;
1467 1529
1468 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe (); 1530 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1469 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R; 1531 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
1470 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case 1532 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
1471 } else { 1533 } else {
1472 pipe $SIGPIPE_R, $SIGPIPE_W; 1534 pipe $SIGPIPE_R, $SIGPIPE_W;
1473 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R; 1535 fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1474 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case 1536 fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1475 1537
1476 # not strictly required, as $^F is normally 2, but let's make sure... 1538 # not strictly required, as $^F is normally 2, but let's make sure...
1477 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; 1539 fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1478 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; 1540 fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1479 } 1541 }
1480 1542
1481 $SIGPIPE_R 1543 $SIGPIPE_R
1482 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; 1544 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1483 1545
1484 $SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec; 1546 $SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1485 } 1547 }
1486 1548
1487 *signal = sub { 1549 *signal = $HAVE_ASYNC_INTERRUPT
1550 ? sub {
1488 my (undef, %arg) = @_; 1551 my (undef, %arg) = @_;
1489 1552
1490 my $signal = uc $arg{signal}
1491 or Carp::croak "required option 'signal' is missing";
1492
1493 if ($HAVE_ASYNC_INTERRUPT) {
1494 # async::interrupt 1553 # async::interrupt
1495
1496 $signal = sig2num $signal; 1554 my $signal = sig2num $arg{signal};
1497 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1555 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1498 1556
1499 $SIG_ASY{$signal} ||= new Async::Interrupt 1557 $SIG_ASY{$signal} ||= new Async::Interrupt
1500 cb => sub { undef $SIG_EV{$signal} }, 1558 cb => sub { undef $SIG_EV{$signal} },
1501 signal => $signal, 1559 signal => $signal,
1502 pipe => [$SIGPIPE_R->filenos], 1560 pipe => [$SIGPIPE_R->filenos],
1503 pipe_autodrain => 0, 1561 pipe_autodrain => 0,
1504 ; 1562 ;
1505 1563
1506 } else { 1564 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1565 }
1566 : sub {
1567 my (undef, %arg) = @_;
1568
1507 # pure perl 1569 # pure perl
1508
1509 # AE::Util has been loaded in signal
1510 $signal = sig2name $signal; 1570 my $signal = sig2name $arg{signal};
1511 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1571 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1512 1572
1513 $SIG{$signal} ||= sub { 1573 $SIG{$signal} ||= sub {
1514 local $!; 1574 local $!;
1515 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV; 1575 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1516 undef $SIG_EV{$signal}; 1576 undef $SIG_EV{$signal};
1517 }; 1577 };
1518 1578
1519 # can't do signal processing without introducing races in pure perl, 1579 # can't do signal processing without introducing races in pure perl,
1520 # so limit the signal latency. 1580 # so limit the signal latency.
1521 _sig_add; 1581 _sig_add;
1522 }
1523 1582
1524 bless [$signal, $arg{cb}], "AnyEvent::Base::signal" 1583 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1584 }
1525 }; 1585 ;
1526 1586
1527 *AnyEvent::Base::signal::DESTROY = sub { 1587 *AnyEvent::Base::signal::DESTROY = sub {
1528 my ($signal, $cb) = @{$_[0]}; 1588 my ($signal, $cb) = @{$_[0]};
1529 1589
1530 _sig_del; 1590 _sig_del;
1537 # print weird messages, or just unconditionally exit 1597 # print weird messages, or just unconditionally exit
1538 # instead of getting the default action. 1598 # instead of getting the default action.
1539 undef $SIG{$signal} 1599 undef $SIG{$signal}
1540 unless keys %{ $SIG_CB{$signal} }; 1600 unless keys %{ $SIG_CB{$signal} };
1541 }; 1601 };
1602
1603 *_signal_exec = sub {
1604 $HAVE_ASYNC_INTERRUPT
1605 ? $SIGPIPE_R->drain
1606 : sysread $SIGPIPE_R, (my $dummy), 9;
1607
1608 while (%SIG_EV) {
1609 for (keys %SIG_EV) {
1610 delete $SIG_EV{$_};
1611 $_->() for values %{ $SIG_CB{$_} || {} };
1612 }
1613 }
1614 };
1542 }; 1615 };
1543 die if $@; 1616 die if $@;
1617
1544 &signal 1618 &signal
1545} 1619}
1546 1620
1547# default implementation for ->child 1621# default implementation for ->child
1548 1622
1549our %PID_CB; 1623our %PID_CB;
1550our $CHLD_W; 1624our $CHLD_W;
1551our $CHLD_DELAY_W; 1625our $CHLD_DELAY_W;
1552our $WNOHANG; 1626our $WNOHANG;
1553 1627
1628# used by many Impl's
1554sub _emit_childstatus($$) { 1629sub _emit_childstatus($$) {
1555 my (undef, $rpid, $rstatus) = @_; 1630 my (undef, $rpid, $rstatus) = @_;
1556 1631
1557 $_->($rpid, $rstatus) 1632 $_->($rpid, $rstatus)
1558 for values %{ $PID_CB{$rpid} || {} }, 1633 for values %{ $PID_CB{$rpid} || {} },
1559 values %{ $PID_CB{0} || {} }; 1634 values %{ $PID_CB{0} || {} };
1560} 1635}
1561 1636
1562sub _sigchld {
1563 my $pid;
1564
1565 AnyEvent->_emit_childstatus ($pid, $?)
1566 while ($pid = waitpid -1, $WNOHANG) > 0;
1567}
1568
1569sub child { 1637sub child {
1638 eval q{ # poor man's autoloading {}
1639 *_sigchld = sub {
1640 my $pid;
1641
1642 AnyEvent->_emit_childstatus ($pid, $?)
1643 while ($pid = waitpid -1, $WNOHANG) > 0;
1644 };
1645
1646 *child = sub {
1570 my (undef, %arg) = @_; 1647 my (undef, %arg) = @_;
1571 1648
1572 defined (my $pid = $arg{pid} + 0) 1649 defined (my $pid = $arg{pid} + 0)
1573 or Carp::croak "required option 'pid' is missing"; 1650 or Carp::croak "required option 'pid' is missing";
1574 1651
1575 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1652 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
1576 1653
1577 # WNOHANG is almost cetrainly 1 everywhere 1654 # WNOHANG is almost cetrainly 1 everywhere
1578 $WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/ 1655 $WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
1579 ? 1 1656 ? 1
1580 : eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; 1657 : eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1581 1658
1582 unless ($CHLD_W) { 1659 unless ($CHLD_W) {
1583 $CHLD_W = AE::signal CHLD => \&_sigchld; 1660 $CHLD_W = AE::signal CHLD => \&_sigchld;
1584 # child could be a zombie already, so make at least one round 1661 # child could be a zombie already, so make at least one round
1585 &_sigchld; 1662 &_sigchld;
1586 } 1663 }
1587 1664
1588 bless [$pid, $arg{cb}], "AnyEvent::Base::child" 1665 bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1589} 1666 };
1590 1667
1591sub AnyEvent::Base::child::DESTROY { 1668 *AnyEvent::Base::child::DESTROY = sub {
1592 my ($pid, $cb) = @{$_[0]}; 1669 my ($pid, $cb) = @{$_[0]};
1593 1670
1594 delete $PID_CB{$pid}{$cb}; 1671 delete $PID_CB{$pid}{$cb};
1595 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1672 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1596 1673
1597 undef $CHLD_W unless keys %PID_CB; 1674 undef $CHLD_W unless keys %PID_CB;
1675 };
1676 };
1677 die if $@;
1678
1679 &child
1598} 1680}
1599 1681
1600# idle emulation is done by simply using a timer, regardless 1682# idle emulation is done by simply using a timer, regardless
1601# of whether the process is idle or not, and not letting 1683# of whether the process is idle or not, and not letting
1602# the callback use more than 50% of the time. 1684# the callback use more than 50% of the time.
1603sub idle { 1685sub idle {
1686 eval q{ # poor man's autoloading {}
1687 *idle = sub {
1604 my (undef, %arg) = @_; 1688 my (undef, %arg) = @_;
1605 1689
1606 my ($cb, $w, $rcb) = $arg{cb}; 1690 my ($cb, $w, $rcb) = $arg{cb};
1607 1691
1608 $rcb = sub { 1692 $rcb = sub {
1609 if ($cb) { 1693 if ($cb) {
1610 $w = _time; 1694 $w = _time;
1611 &$cb; 1695 &$cb;
1612 $w = _time - $w; 1696 $w = _time - $w;
1613 1697
1614 # never use more then 50% of the time for the idle watcher, 1698 # never use more then 50% of the time for the idle watcher,
1615 # within some limits 1699 # within some limits
1616 $w = 0.0001 if $w < 0.0001; 1700 $w = 0.0001 if $w < 0.0001;
1617 $w = 5 if $w > 5; 1701 $w = 5 if $w > 5;
1618 1702
1619 $w = AE::timer $w, 0, $rcb; 1703 $w = AE::timer $w, 0, $rcb;
1620 } else { 1704 } else {
1621 # clean up... 1705 # clean up...
1622 undef $w; 1706 undef $w;
1623 undef $rcb; 1707 undef $rcb;
1708 }
1709 };
1710
1711 $w = AE::timer 0.05, 0, $rcb;
1712
1713 bless \\$cb, "AnyEvent::Base::idle"
1624 } 1714 };
1715
1716 *AnyEvent::Base::idle::DESTROY = sub {
1717 undef $${$_[0]};
1718 };
1625 }; 1719 };
1720 die if $@;
1626 1721
1627 $w = AE::timer 0.05, 0, $rcb; 1722 &idle
1628
1629 bless \\$cb, "AnyEvent::Base::idle"
1630}
1631
1632sub AnyEvent::Base::idle::DESTROY {
1633 undef $${$_[0]};
1634} 1723}
1635 1724
1636package AnyEvent::CondVar; 1725package AnyEvent::CondVar;
1637 1726
1638our @ISA = AnyEvent::CondVar::Base::; 1727our @ISA = AnyEvent::CondVar::Base::;
1912 warn "read: $input\n"; # output what has been read 2001 warn "read: $input\n"; # output what has been read
1913 $cv->send if $input =~ /^q/i; # quit program if /^q/i 2002 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1914 }, 2003 },
1915 ); 2004 );
1916 2005
1917 my $time_watcher; # can only be used once
1918
1919 sub new_timer {
1920 $timer = AnyEvent->timer (after => 1, cb => sub { 2006 my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1921 warn "timeout\n"; # print 'timeout' about every second 2007 warn "timeout\n"; # print 'timeout' at most every second
1922 &new_timer; # and restart the time
1923 }); 2008 });
1924 }
1925
1926 new_timer; # create first timer
1927 2009
1928 $cv->recv; # wait until user enters /^q/i 2010 $cv->recv; # wait until user enters /^q/i
1929 2011
1930=head1 REAL-WORLD EXAMPLE 2012=head1 REAL-WORLD EXAMPLE
1931 2013
2004 2086
2005The actual code goes further and collects all errors (C<die>s, exceptions) 2087The actual code goes further and collects all errors (C<die>s, exceptions)
2006that occurred during request processing. The C<result> method detects 2088that occurred during request processing. The C<result> method detects
2007whether an exception as thrown (it is stored inside the $txn object) 2089whether an exception as thrown (it is stored inside the $txn object)
2008and just throws the exception, which means connection errors and other 2090and just throws the exception, which means connection errors and other
2009problems get reported tot he code that tries to use the result, not in a 2091problems get reported to the code that tries to use the result, not in a
2010random callback. 2092random callback.
2011 2093
2012All of this enables the following usage styles: 2094All of this enables the following usage styles:
2013 2095
20141. Blocking: 20961. Blocking:
2375As you can see, the AnyEvent + EV combination even beats the 2457As you can see, the AnyEvent + EV combination even beats the
2376hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl 2458hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2377backend easily beats IO::Lambda and POE. 2459backend easily beats IO::Lambda and POE.
2378 2460
2379And even the 100% non-blocking version written using the high-level (and 2461And even the 100% non-blocking version written using the high-level (and
2380slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a 2462slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2381large margin, even though it does all of DNS, tcp-connect and socket I/O 2463higher level ("unoptimised") abstractions by a large margin, even though
2382in a non-blocking way. 2464it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2383 2465
2384The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and 2466The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2385F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are 2467F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2386part of the IO::lambda distribution and were used without any changes. 2468part of the IO::Lambda distribution and were used without any changes.
2387 2469
2388 2470
2389=head1 SIGNALS 2471=head1 SIGNALS
2390 2472
2391AnyEvent currently installs handlers for these signals: 2473AnyEvent currently installs handlers for these signals:
2433it's built-in modules) are required to use it. 2515it's built-in modules) are required to use it.
2434 2516
2435That does not mean that AnyEvent won't take advantage of some additional 2517That does not mean that AnyEvent won't take advantage of some additional
2436modules if they are installed. 2518modules if they are installed.
2437 2519
2438This section epxlains which additional modules will be used, and how they 2520This section explains which additional modules will be used, and how they
2439affect AnyEvent's operetion. 2521affect AnyEvent's operation.
2440 2522
2441=over 4 2523=over 4
2442 2524
2443=item L<Async::Interrupt> 2525=item L<Async::Interrupt>
2444 2526
2449catch the signals) with some delay (default is 10 seconds, look for 2531catch the signals) with some delay (default is 10 seconds, look for
2450C<$AnyEvent::MAX_SIGNAL_LATENCY>). 2532C<$AnyEvent::MAX_SIGNAL_LATENCY>).
2451 2533
2452If this module is available, then it will be used to implement signal 2534If this module is available, then it will be used to implement signal
2453catching, which means that signals will not be delayed, and the event loop 2535catching, which means that signals will not be delayed, and the event loop
2454will not be interrupted regularly, which is more efficient (And good for 2536will not be interrupted regularly, which is more efficient (and good for
2455battery life on laptops). 2537battery life on laptops).
2456 2538
2457This affects not just the pure-perl event loop, but also other event loops 2539This affects not just the pure-perl event loop, but also other event loops
2458that have no signal handling on their own (e.g. Glib, Tk, Qt). 2540that have no signal handling on their own (e.g. Glib, Tk, Qt).
2459 2541
2471automatic timer adjustments even when no monotonic clock is available, 2553automatic timer adjustments even when no monotonic clock is available,
2472can take avdantage of advanced kernel interfaces such as C<epoll> and 2554can take avdantage of advanced kernel interfaces such as C<epoll> and
2473C<kqueue>, and is the fastest backend I<by far>. You can even embed 2555C<kqueue>, and is the fastest backend I<by far>. You can even embed
2474L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>). 2556L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
2475 2557
2558If you only use backends that rely on another event loop (e.g. C<Tk>),
2559then this module will do nothing for you.
2560
2476=item L<Guard> 2561=item L<Guard>
2477 2562
2478The guard module, when used, will be used to implement 2563The guard module, when used, will be used to implement
2479C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a 2564C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
2480lot less memory), but otherwise doesn't affect guard operation much. It is 2565lot less memory), but otherwise doesn't affect guard operation much. It is
2481purely used for performance. 2566purely used for performance.
2482 2567
2483=item L<JSON> and L<JSON::XS> 2568=item L<JSON> and L<JSON::XS>
2484 2569
2485This module is required when you want to read or write JSON data via 2570One of these modules is required when you want to read or write JSON data
2486L<AnyEvent::Handle>. It is also written in pure-perl, but can take 2571via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
2487advantage of the ultra-high-speed L<JSON::XS> module when it is installed. 2572advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
2488
2489In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
2490installed.
2491 2573
2492=item L<Net::SSLeay> 2574=item L<Net::SSLeay>
2493 2575
2494Implementing TLS/SSL in Perl is certainly interesting, but not very 2576Implementing TLS/SSL in Perl is certainly interesting, but not very
2495worthwhile: If this module is installed, then L<AnyEvent::Handle> (with 2577worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
2506 2588
2507 2589
2508=head1 FORK 2590=head1 FORK
2509 2591
2510Most event libraries are not fork-safe. The ones who are usually are 2592Most event libraries are not fork-safe. The ones who are usually are
2511because they rely on inefficient but fork-safe C<select> or C<poll> 2593because they rely on inefficient but fork-safe C<select> or C<poll> calls
2512calls. Only L<EV> is fully fork-aware. 2594- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
2595are usually badly thought-out hacks that are incompatible with fork in
2596one way or another. Only L<EV> is fully fork-aware and ensures that you
2597continue event-processing in both parent and child (or both, if you know
2598what you are doing).
2599
2600This means that, in general, you cannot fork and do event processing in
2601the child if the event library was initialised before the fork (which
2602usually happens when the first AnyEvent watcher is created, or the library
2603is loaded).
2513 2604
2514If you have to fork, you must either do so I<before> creating your first 2605If you have to fork, you must either do so I<before> creating your first
2515watcher OR you must not use AnyEvent at all in the child OR you must do 2606watcher OR you must not use AnyEvent at all in the child OR you must do
2516something completely out of the scope of AnyEvent. 2607something completely out of the scope of AnyEvent.
2608
2609The problem of doing event processing in the parent I<and> the child
2610is much more complicated: even for backends that I<are> fork-aware or
2611fork-safe, their behaviour is not usually what you want: fork clones all
2612watchers, that means all timers, I/O watchers etc. are active in both
2613parent and child, which is almost never what you want. USing C<exec>
2614to start worker children from some kind of manage rprocess is usually
2615preferred, because it is much easier and cleaner, at the expense of having
2616to have another binary.
2517 2617
2518 2618
2519=head1 SECURITY CONSIDERATIONS 2619=head1 SECURITY CONSIDERATIONS
2520 2620
2521AnyEvent can be forced to load any event model via 2621AnyEvent can be forced to load any event model via

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