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Revision 1.240 by root, Fri Jul 17 14:57:03 2009 UTC vs.
Revision 1.251 by root, Mon Jul 20 22:39:57 2009 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - events independent of event loop implementation
4 4
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
6event loops. 6event loops.
7 7
8=head1 SYNOPSIS 8=head1 SYNOPSIS
… …
40=head1 INTRODUCTION/TUTORIAL 40=head1 INTRODUCTION/TUTORIAL
41 41
42This manpage is mainly a reference manual. If you are interested 42This manpage is mainly a reference manual. If you are interested
43in a tutorial or some gentle introduction, have a look at the 43in a tutorial or some gentle introduction, have a look at the
44L<AnyEvent::Intro> manpage. 44L<AnyEvent::Intro> manpage.
45
46=head1 SUPPORT
47
48There is a mailinglist for discussing all things AnyEvent, and an IRC
49channel, too.
50
51See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
52Respository>, at L<http://anyevent.schmorp.de>, for more info.
45 53
46=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 54=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
47 55
48Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 56Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
49nowadays. So what is different about AnyEvent? 57nowadays. So what is different about AnyEvent?
… …
361invocation, and callback invocation will be synchronous. Synchronous means 369invocation, and callback invocation will be synchronous. Synchronous means
362that it might take a while until the signal gets handled by the process, 370that it might take a while until the signal gets handled by the process,
363but it is guaranteed not to interrupt any other callbacks. 371but it is guaranteed not to interrupt any other callbacks.
364 372
365The main advantage of using these watchers is that you can share a signal 373The main advantage of using these watchers is that you can share a signal
366between multiple watchers. 374between multiple watchers, and AnyEvent will ensure that signals will not
375interrupt your program at bad times.
367 376
368This watcher might use C<%SIG>, so programs overwriting those signals 377This watcher might use C<%SIG> (depending on the event loop used),
369directly will likely not work correctly. 378so programs overwriting those signals directly will likely not work
379correctly.
370 380
371Example: exit on SIGINT 381Example: exit on SIGINT
372 382
373 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); 383 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
384
385=head3 Signal Races, Delays and Workarounds
386
387Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
388callbacks to signals in a generic way, which is a pity, as you cannot do
389race-free signal handling in perl. AnyEvent will try to do it's best, but
390in some cases, signals will be delayed. The maximum time a signal might
391be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
392seconds). This variable can be changed only before the first signal
393watcher is created, and should be left alone otherwise. Higher values
394will cause fewer spurious wake-ups, which is better for power and CPU
395saving. All these problems can be avoided by installing the optional
396L<Async::Interrupt> module. This will not work with inherently broken
397event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
398currently, as POE does it's own workaround with one-second latency). With
399those, you just have to suffer the delays.
374 400
375=head2 CHILD PROCESS WATCHERS 401=head2 CHILD PROCESS WATCHERS
376 402
377You can also watch on a child process exit and catch its exit status. 403You can also watch on a child process exit and catch its exit status.
378 404
… …
403 429
404This means you cannot create a child watcher as the very first 430This means you cannot create a child watcher as the very first
405thing in an AnyEvent program, you I<have> to create at least one 431thing in an AnyEvent program, you I<have> to create at least one
406watcher before you C<fork> the child (alternatively, you can call 432watcher before you C<fork> the child (alternatively, you can call
407C<AnyEvent::detect>). 433C<AnyEvent::detect>).
434
435As most event loops do not support waiting for child events, they will be
436emulated by AnyEvent in most cases, in which the latency and race problems
437mentioned in the description of signal watchers apply.
408 438
409Example: fork a process and wait for it 439Example: fork a process and wait for it
410 440
411 my $done = AnyEvent->condvar; 441 my $done = AnyEvent->condvar;
412 442
… …
487Condition variables are similar to callbacks, except that you can 517Condition variables are similar to callbacks, except that you can
488optionally wait for them. They can also be called merge points - points 518optionally wait for them. They can also be called merge points - points
489in time where multiple outstanding events have been processed. And yet 519in time where multiple outstanding events have been processed. And yet
490another way to call them is transactions - each condition variable can be 520another way to call them is transactions - each condition variable can be
491used to represent a transaction, which finishes at some point and delivers 521used to represent a transaction, which finishes at some point and delivers
492a result. 522a result. And yet some people know them as "futures" - a promise to
523compute/deliver something that you can wait for.
493 524
494Condition variables are very useful to signal that something has finished, 525Condition variables are very useful to signal that something has finished,
495for example, if you write a module that does asynchronous http requests, 526for example, if you write a module that does asynchronous http requests,
496then a condition variable would be the ideal candidate to signal the 527then a condition variable would be the ideal candidate to signal the
497availability of results. The user can either act when the callback is 528availability of results. The user can either act when the callback is
… …
1024 1055
1025=cut 1056=cut
1026 1057
1027package AnyEvent; 1058package AnyEvent;
1028 1059
1060# basically a tuned-down version of common::sense
1061sub common_sense {
1029no warnings; 1062 # no warnings
1063 ${^WARNING_BITS} ^= ${^WARNING_BITS};
1030use strict qw(vars subs); 1064 # use strict vars subs
1065 $^H |= 0x00000600;
1066}
1067
1068BEGIN { AnyEvent::common_sense }
1031 1069
1032use Carp (); 1070use Carp ();
1033 1071
1034our $VERSION = 4.83; 1072our $VERSION = 4.86;
1035our $MODEL; 1073our $MODEL;
1036 1074
1037our $AUTOLOAD; 1075our $AUTOLOAD;
1038our @ISA; 1076our @ISA;
1039 1077
1040our @REGISTRY; 1078our @REGISTRY;
1041 1079
1042our $WIN32; 1080our $WIN32;
1081
1082our $VERBOSE;
1043 1083
1044BEGIN { 1084BEGIN {
1045 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }"; 1085 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
1046 eval "sub TAINT(){ " . (${^TAINT}*1) . " }"; 1086 eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
1047 1087
1048 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} 1088 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1049 if ${^TAINT}; 1089 if ${^TAINT};
1050}
1051 1090
1052our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 1091 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
1092
1093}
1094
1095our $MAX_SIGNAL_LATENCY = 10;
1053 1096
1054our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred 1097our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
1055 1098
1056{ 1099{
1057 my $idx; 1100 my $idx;
… …
1108 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1151 @post_detect = grep $_ != ${$_[0]}, @post_detect;
1109} 1152}
1110 1153
1111sub detect() { 1154sub detect() {
1112 unless ($MODEL) { 1155 unless ($MODEL) {
1113 no strict 'refs';
1114 local $SIG{__DIE__}; 1156 local $SIG{__DIE__};
1115 1157
1116 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 1158 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1117 my $model = "AnyEvent::Impl::$1"; 1159 my $model = "AnyEvent::Impl::$1";
1118 if (eval "require $model") { 1160 if (eval "require $model") {
1119 $MODEL = $model; 1161 $MODEL = $model;
1120 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $verbose > 1; 1162 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1121 } else { 1163 } else {
1122 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $verbose; 1164 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1123 } 1165 }
1124 } 1166 }
1125 1167
1126 # check for already loaded models 1168 # check for already loaded models
1127 unless ($MODEL) { 1169 unless ($MODEL) {
1128 for (@REGISTRY, @models) { 1170 for (@REGISTRY, @models) {
1129 my ($package, $model) = @$_; 1171 my ($package, $model) = @$_;
1130 if (${"$package\::VERSION"} > 0) { 1172 if (${"$package\::VERSION"} > 0) {
1131 if (eval "require $model") { 1173 if (eval "require $model") {
1132 $MODEL = $model; 1174 $MODEL = $model;
1133 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; 1175 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1134 last; 1176 last;
1135 } 1177 }
1136 } 1178 }
1137 } 1179 }
1138 1180
… …
1143 my ($package, $model) = @$_; 1185 my ($package, $model) = @$_;
1144 if (eval "require $package" 1186 if (eval "require $package"
1145 and ${"$package\::VERSION"} > 0 1187 and ${"$package\::VERSION"} > 0
1146 and eval "require $model") { 1188 and eval "require $model") {
1147 $MODEL = $model; 1189 $MODEL = $model;
1148 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; 1190 warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
1149 last; 1191 last;
1150 } 1192 }
1151 } 1193 }
1152 1194
1153 $MODEL 1195 $MODEL
… …
1184# allow only one watcher per fd, so we dup it to get a different one). 1226# allow only one watcher per fd, so we dup it to get a different one).
1185sub _dupfh($$;$$) { 1227sub _dupfh($$;$$) {
1186 my ($poll, $fh, $r, $w) = @_; 1228 my ($poll, $fh, $r, $w) = @_;
1187 1229
1188 # cygwin requires the fh mode to be matching, unix doesn't 1230 # cygwin requires the fh mode to be matching, unix doesn't
1189 my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">"); 1231 my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1190 1232
1191 open my $fh2, "$mode&", $fh 1233 open my $fh2, $mode, $fh
1192 or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,"; 1234 or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1193 1235
1194 # we assume CLOEXEC is already set by perl in all important cases 1236 # we assume CLOEXEC is already set by perl in all important cases
1195 1237
1196 ($fh2, $rw) 1238 ($fh2, $rw)
… …
1198 1240
1199package AnyEvent::Base; 1241package AnyEvent::Base;
1200 1242
1201# default implementations for many methods 1243# default implementations for many methods
1202 1244
1203BEGIN { 1245sub _time {
1246 # probe for availability of Time::HiRes
1204 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { 1247 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1248 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1205 *_time = \&Time::HiRes::time; 1249 *_time = \&Time::HiRes::time;
1206 # if (eval "use POSIX (); (POSIX::times())... 1250 # if (eval "use POSIX (); (POSIX::times())...
1207 } else { 1251 } else {
1252 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1208 *_time = sub { time }; # epic fail 1253 *_time = sub { time }; # epic fail
1209 } 1254 }
1255
1256 &_time
1210} 1257}
1211 1258
1212sub time { _time } 1259sub time { _time }
1213sub now { _time } 1260sub now { _time }
1214sub now_update { } 1261sub now_update { }
… …
1219 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" 1266 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1220} 1267}
1221 1268
1222# default implementation for ->signal 1269# default implementation for ->signal
1223 1270
1271our $HAVE_ASYNC_INTERRUPT;
1224our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); 1272our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1273our (%SIG_ASY, %SIG_ASY_W);
1274our ($SIG_COUNT, $SIG_TW);
1225 1275
1226sub _signal_exec { 1276sub _signal_exec {
1277 $HAVE_ASYNC_INTERRUPT
1278 ? $SIGPIPE_R->drain
1227 sysread $SIGPIPE_R, my $dummy, 4; 1279 : sysread $SIGPIPE_R, my $dummy, 9;
1228 1280
1229 while (%SIG_EV) { 1281 while (%SIG_EV) {
1230 for (keys %SIG_EV) { 1282 for (keys %SIG_EV) {
1231 delete $SIG_EV{$_}; 1283 delete $SIG_EV{$_};
1232 $_->() for values %{ $SIG_CB{$_} || {} }; 1284 $_->() for values %{ $SIG_CB{$_} || {} };
1233 } 1285 }
1234 } 1286 }
1235} 1287}
1236 1288
1289# install a dumym wakeupw atcher to reduce signal catching latency
1290sub _sig_add() {
1291 unless ($SIG_COUNT++) {
1292 # try to align timer on a full-second boundary, if possible
1293 my $NOW = AnyEvent->now;
1294
1295 $SIG_TW = AnyEvent->timer (
1296 after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
1297 interval => $MAX_SIGNAL_LATENCY,
1298 cb => sub { }, # just for the PERL_ASYNC_CHECK
1299 );
1300 }
1301}
1302
1303sub _sig_del {
1304 undef $SIG_TW
1305 unless --$SIG_COUNT;
1306}
1307
1308sub _signal {
1309 my (undef, %arg) = @_;
1310
1311 my $signal = uc $arg{signal}
1312 or Carp::croak "required option 'signal' is missing";
1313
1314 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1315
1316 if ($HAVE_ASYNC_INTERRUPT) {
1317 # async::interrupt
1318
1319 $SIG_ASY{$signal} ||= do {
1320 my $asy = new Async::Interrupt
1321 cb => sub { undef $SIG_EV{$signal} },
1322 signal => $signal,
1323 pipe => [$SIGPIPE_R->filenos],
1324 ;
1325 $asy->pipe_autodrain (0);
1326
1327 $asy
1328 };
1329
1330 } else {
1331 # pure perl
1332
1333 $SIG{$signal} ||= sub {
1334 local $!;
1335 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1336 undef $SIG_EV{$signal};
1337 };
1338
1339 # can't do signal processing without introducing races in pure perl,
1340 # so limit the signal latency.
1341 _sig_add;
1342 }
1343
1344 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1345}
1346
1237sub signal { 1347sub signal {
1238 my (undef, %arg) = @_; 1348 # probe for availability of Async::Interrupt
1349 if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
1350 warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1239 1351
1240 unless ($SIGPIPE_R) { 1352 $HAVE_ASYNC_INTERRUPT = 1;
1353 $SIGPIPE_R = new Async::Interrupt::EventPipe;
1354 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
1355
1356 } else {
1357 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1358
1241 require Fcntl; 1359 require Fcntl;
1242 1360
1243 if (AnyEvent::WIN32) { 1361 if (AnyEvent::WIN32) {
1244 require AnyEvent::Util; 1362 require AnyEvent::Util;
1245 1363
… …
1260 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; 1378 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1261 1379
1262 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec); 1380 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1263 } 1381 }
1264 1382
1265 my $signal = uc $arg{signal} 1383 *signal = \&_signal;
1266 or Carp::croak "required option 'signal' is missing"; 1384 &signal
1267
1268 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1269 $SIG{$signal} ||= sub {
1270 local $!;
1271 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1272 undef $SIG_EV{$signal};
1273 };
1274
1275 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1276} 1385}
1277 1386
1278sub AnyEvent::Base::signal::DESTROY { 1387sub AnyEvent::Base::signal::DESTROY {
1279 my ($signal, $cb) = @{$_[0]}; 1388 my ($signal, $cb) = @{$_[0]};
1280 1389
1390 _sig_del;
1391
1281 delete $SIG_CB{$signal}{$cb}; 1392 delete $SIG_CB{$signal}{$cb};
1282 1393
1394 $HAVE_ASYNC_INTERRUPT
1395 ? delete $SIG_ASY{$signal}
1283 # delete doesn't work with older perls - they then 1396 : # delete doesn't work with older perls - they then
1284 # print weird messages, or just unconditionally exit 1397 # print weird messages, or just unconditionally exit
1285 # instead of getting the default action. 1398 # instead of getting the default action.
1399 undef $SIG{$signal}
1286 undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; 1400 unless keys %{ $SIG_CB{$signal} };
1287} 1401}
1288 1402
1289# default implementation for ->child 1403# default implementation for ->child
1290 1404
1291our %PID_CB; 1405our %PID_CB;
… …
1293our $CHLD_DELAY_W; 1407our $CHLD_DELAY_W;
1294our $WNOHANG; 1408our $WNOHANG;
1295 1409
1296sub _sigchld { 1410sub _sigchld {
1297 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1411 while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1412 $_->($pid, $?)
1298 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), 1413 for values %{ $PID_CB{$pid} || {} },
1299 (values %{ $PID_CB{0} || {} }); 1414 values %{ $PID_CB{0} || {} };
1300 } 1415 }
1301} 1416}
1302 1417
1303sub child { 1418sub child {
1304 my (undef, %arg) = @_; 1419 my (undef, %arg) = @_;
… …
1306 defined (my $pid = $arg{pid} + 0) 1421 defined (my $pid = $arg{pid} + 0)
1307 or Carp::croak "required option 'pid' is missing"; 1422 or Carp::croak "required option 'pid' is missing";
1308 1423
1309 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1424 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
1310 1425
1426 # WNOHANG is almost cetrainly 1 everywhere
1427 $WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
1428 ? 1
1311 $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; 1429 : eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1312 1430
1313 unless ($CHLD_W) { 1431 unless ($CHLD_W) {
1314 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1432 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1315 # child could be a zombie already, so make at least one round 1433 # child could be a zombie already, so make at least one round
1316 &_sigchld; 1434 &_sigchld;
… …
1368 1486
1369our @ISA = AnyEvent::CondVar::Base::; 1487our @ISA = AnyEvent::CondVar::Base::;
1370 1488
1371package AnyEvent::CondVar::Base; 1489package AnyEvent::CondVar::Base;
1372 1490
1373use overload 1491#use overload
1374 '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, 1492# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1375 fallback => 1; 1493# fallback => 1;
1494
1495# save 300+ kilobytes by dirtily hardcoding overloading
1496${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
1497*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
1498*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
1499${'AnyEvent::CondVar::Base::()'} = 1; # fallback
1376 1500
1377our $WAITING; 1501our $WAITING;
1378 1502
1379sub _send { 1503sub _send {
1380 # nop 1504 # nop
… …
1471C<PERL_ANYEVENT_MODEL>. 1595C<PERL_ANYEVENT_MODEL>.
1472 1596
1473When set to C<2> or higher, cause AnyEvent to report to STDERR which event 1597When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1474model it chooses. 1598model it chooses.
1475 1599
1600When set to C<8> or higher, then AnyEvent will report extra information on
1601which optional modules it loads and how it implements certain features.
1602
1476=item C<PERL_ANYEVENT_STRICT> 1603=item C<PERL_ANYEVENT_STRICT>
1477 1604
1478AnyEvent does not do much argument checking by default, as thorough 1605AnyEvent does not do much argument checking by default, as thorough
1479argument checking is very costly. Setting this variable to a true value 1606argument checking is very costly. Setting this variable to a true value
1480will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly 1607will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1481check the arguments passed to most method calls. If it finds any problems, 1608check the arguments passed to most method calls. If it finds any problems,
1482it will croak. 1609it will croak.
1483 1610
1484In other words, enables "strict" mode. 1611In other words, enables "strict" mode.
1485 1612
1486Unlike C<use strict>, it is definitely recommended to keep it off in 1613Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1487production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while 1614>>, it is definitely recommended to keep it off in production. Keeping
1488developing programs can be very useful, however. 1615C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1616can be very useful, however.
1489 1617
1490=item C<PERL_ANYEVENT_MODEL> 1618=item C<PERL_ANYEVENT_MODEL>
1491 1619
1492This can be used to specify the event model to be used by AnyEvent, before 1620This can be used to specify the event model to be used by AnyEvent, before
1493auto detection and -probing kicks in. It must be a string consisting 1621auto detection and -probing kicks in. It must be a string consisting
… …
1555 1683
1556When neither C<ca_file> nor C<ca_path> was specified during 1684When neither C<ca_file> nor C<ca_path> was specified during
1557L<AnyEvent::TLS> context creation, and either of these environment 1685L<AnyEvent::TLS> context creation, and either of these environment
1558variables exist, they will be used to specify CA certificate locations 1686variables exist, they will be used to specify CA certificate locations
1559instead of a system-dependent default. 1687instead of a system-dependent default.
1688
1689=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
1690
1691When these are set to C<1>, then the respective modules are not
1692loaded. Mostly good for testing AnyEvent itself.
1560 1693
1561=back 1694=back
1562 1695
1563=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1696=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1564 1697
… …
2132 if $SIG{CHLD} eq 'IGNORE'; 2265 if $SIG{CHLD} eq 'IGNORE';
2133 2266
2134$SIG{PIPE} = sub { } 2267$SIG{PIPE} = sub { }
2135 unless defined $SIG{PIPE}; 2268 unless defined $SIG{PIPE};
2136 2269
2270=head1 RECOMMENDED/OPTIONAL MODULES
2271
2272One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
2273it's built-in modules) are required to use it.
2274
2275That does not mean that AnyEvent won't take advantage of some additional
2276modules if they are installed.
2277
2278This section epxlains which additional modules will be used, and how they
2279affect AnyEvent's operetion.
2280
2281=over 4
2282
2283=item L<Async::Interrupt>
2284
2285This slightly arcane module is used to implement fast signal handling: To
2286my knowledge, there is no way to do completely race-free and quick
2287signal handling in pure perl. To ensure that signals still get
2288delivered, AnyEvent will start an interval timer to wake up perl (and
2289catch the signals) with some delay (default is 10 seconds, look for
2290C<$AnyEvent::MAX_SIGNAL_LATENCY>).
2291
2292If this module is available, then it will be used to implement signal
2293catching, which means that signals will not be delayed, and the event loop
2294will not be interrupted regularly, which is more efficient (And good for
2295battery life on laptops).
2296
2297This affects not just the pure-perl event loop, but also other event loops
2298that have no signal handling on their own (e.g. Glib, Tk, Qt).
2299
2300Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
2301and either employ their own workarounds (POE) or use AnyEvent's workaround
2302(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
2303does nothing for those backends.
2304
2305=item L<EV>
2306
2307This module isn't really "optional", as it is simply one of the backend
2308event loops that AnyEvent can use. However, it is simply the best event
2309loop available in terms of features, speed and stability: It supports
2310the AnyEvent API optimally, implements all the watcher types in XS, does
2311automatic timer adjustments even when no monotonic clock is available,
2312can take avdantage of advanced kernel interfaces such as C<epoll> and
2313C<kqueue>, and is the fastest backend I<by far>. You can even embed
2314L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
2315
2316=item L<Guard>
2317
2318The guard module, when used, will be used to implement
2319C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
2320lot less memory), but otherwise doesn't affect guard operation much. It is
2321purely used for performance.
2322
2323=item L<JSON> and L<JSON::XS>
2324
2325This module is required when you want to read or write JSON data via
2326L<AnyEvent::Handle>. It is also written in pure-perl, but can take
2327advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
2328
2329In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
2330installed.
2331
2332=item L<Net::SSLeay>
2333
2334Implementing TLS/SSL in Perl is certainly interesting, but not very
2335worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
2336the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
2337
2338=item L<Time::HiRes>
2339
2340This module is part of perl since release 5.008. It will be used when the
2341chosen event library does not come with a timing source on it's own. The
2342pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
2343try to use a monotonic clock for timing stability.
2344
2345=back
2346
2347
2137=head1 FORK 2348=head1 FORK
2138 2349
2139Most event libraries are not fork-safe. The ones who are usually are 2350Most event libraries are not fork-safe. The ones who are usually are
2140because they rely on inefficient but fork-safe C<select> or C<poll> 2351because they rely on inefficient but fork-safe C<select> or C<poll>
2141calls. Only L<EV> is fully fork-aware. 2352calls. Only L<EV> is fully fork-aware.
2142 2353
2143If you have to fork, you must either do so I<before> creating your first 2354If you have to fork, you must either do so I<before> creating your first
2144watcher OR you must not use AnyEvent at all in the child. 2355watcher OR you must not use AnyEvent at all in the child OR you must do
2356something completely out of the scope of AnyEvent.
2145 2357
2146 2358
2147=head1 SECURITY CONSIDERATIONS 2359=head1 SECURITY CONSIDERATIONS
2148 2360
2149AnyEvent can be forced to load any event model via 2361AnyEvent can be forced to load any event model via

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