ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/AnyEvent/lib/AnyEvent.pm
(Generate patch)

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.127 by root, Sat May 24 01:15:19 2008 UTC vs.
Revision 1.132 by root, Sun May 25 01:05:27 2008 UTC

57as those use one of the supported event loops. It is trivial to add new 57as those use one of the supported event loops. It is trivial to add new
58event loops to AnyEvent, too, so it is future-proof). 58event loops to AnyEvent, too, so it is future-proof).
59 59
60In addition to being free of having to use I<the one and only true event 60In addition to being free of having to use I<the one and only true event
61model>, AnyEvent also is free of bloat and policy: with POE or similar 61model>, AnyEvent also is free of bloat and policy: with POE or similar
62modules, you get an enourmous amount of code and strict rules you have to 62modules, you get an enormous amount of code and strict rules you have to
63follow. AnyEvent, on the other hand, is lean and up to the point, by only 63follow. AnyEvent, on the other hand, is lean and up to the point, by only
64offering the functionality that is necessary, in as thin as a wrapper as 64offering the functionality that is necessary, in as thin as a wrapper as
65technically possible. 65technically possible.
66 66
67Of course, if you want lots of policy (this can arguably be somewhat 67Of course, if you want lots of policy (this can arguably be somewhat
108 108
109=head1 WATCHERS 109=head1 WATCHERS
110 110
111AnyEvent has the central concept of a I<watcher>, which is an object that 111AnyEvent has the central concept of a I<watcher>, which is an object that
112stores relevant data for each kind of event you are waiting for, such as 112stores relevant data for each kind of event you are waiting for, such as
113the callback to call, the filehandle to watch, etc. 113the callback to call, the file handle to watch, etc.
114 114
115These watchers are normal Perl objects with normal Perl lifetime. After 115These watchers are normal Perl objects with normal Perl lifetime. After
116creating a watcher it will immediately "watch" for events and invoke the 116creating a watcher it will immediately "watch" for events and invoke the
117callback when the event occurs (of course, only when the event model 117callback when the event occurs (of course, only when the event model
118is in control). 118is in control).
237 237
238Although the callback might get passed parameters, their value and 238Although the callback might get passed parameters, their value and
239presence is undefined and you cannot rely on them. Portable AnyEvent 239presence is undefined and you cannot rely on them. Portable AnyEvent
240callbacks cannot use arguments passed to signal watcher callbacks. 240callbacks cannot use arguments passed to signal watcher callbacks.
241 241
242Multiple signal occurances can be clumped together into one callback 242Multiple signal occurrences can be clumped together into one callback
243invocation, and callback invocation will be synchronous. synchronous means 243invocation, and callback invocation will be synchronous. Synchronous means
244that it might take a while until the signal gets handled by the process, 244that it might take a while until the signal gets handled by the process,
245but it is guarenteed not to interrupt any other callbacks. 245but it is guaranteed not to interrupt any other callbacks.
246 246
247The main advantage of using these watchers is that you can share a signal 247The main advantage of using these watchers is that you can share a signal
248between multiple watchers. 248between multiple watchers.
249 249
250This watcher might use C<%SIG>, so programs overwriting those signals 250This watcher might use C<%SIG>, so programs overwriting those signals
310Condition variables can be created by calling the C<< AnyEvent->condvar 310Condition variables can be created by calling the C<< AnyEvent->condvar
311>> method, usually without arguments. The only argument pair allowed is 311>> method, usually without arguments. The only argument pair allowed is
312C<cb>, which specifies a callback to be called when the condition variable 312C<cb>, which specifies a callback to be called when the condition variable
313becomes true. 313becomes true.
314 314
315After creation, the conditon variable is "false" until it becomes "true" 315After creation, the condition variable is "false" until it becomes "true"
316by calling the C<send> method. 316by calling the C<send> method (or calling the condition variable as if it
317were a callback).
317 318
318Condition variables are similar to callbacks, except that you can 319Condition variables are similar to callbacks, except that you can
319optionally wait for them. They can also be called merge points - points 320optionally wait for them. They can also be called merge points - points
320in time where multiple outstandign events have been processed. And yet 321in time where multiple outstanding events have been processed. And yet
321another way to call them is transations - each condition variable can be 322another way to call them is transactions - each condition variable can be
322used to represent a transaction, which finishes at some point and delivers 323used to represent a transaction, which finishes at some point and delivers
323a result. 324a result.
324 325
325Condition variables are very useful to signal that something has finished, 326Condition variables are very useful to signal that something has finished,
326for example, if you write a module that does asynchronous http requests, 327for example, if you write a module that does asynchronous http requests,
332you can block your main program until an event occurs - for example, you 333you can block your main program until an event occurs - for example, you
333could C<< ->recv >> in your main program until the user clicks the Quit 334could C<< ->recv >> in your main program until the user clicks the Quit
334button of your app, which would C<< ->send >> the "quit" event. 335button of your app, which would C<< ->send >> the "quit" event.
335 336
336Note that condition variables recurse into the event loop - if you have 337Note that condition variables recurse into the event loop - if you have
337two pieces of code that call C<< ->recv >> in a round-robbin fashion, you 338two pieces of code that call C<< ->recv >> in a round-robin fashion, you
338lose. Therefore, condition variables are good to export to your caller, but 339lose. Therefore, condition variables are good to export to your caller, but
339you should avoid making a blocking wait yourself, at least in callbacks, 340you should avoid making a blocking wait yourself, at least in callbacks,
340as this asks for trouble. 341as this asks for trouble.
341 342
342Condition variables are represented by hash refs in perl, and the keys 343Condition variables are represented by hash refs in perl, and the keys
347 348
348There are two "sides" to a condition variable - the "producer side" which 349There are two "sides" to a condition variable - the "producer side" which
349eventually calls C<< -> send >>, and the "consumer side", which waits 350eventually calls C<< -> send >>, and the "consumer side", which waits
350for the send to occur. 351for the send to occur.
351 352
352Example: 353Example: wait for a timer.
353 354
354 # wait till the result is ready 355 # wait till the result is ready
355 my $result_ready = AnyEvent->condvar; 356 my $result_ready = AnyEvent->condvar;
356 357
357 # do something such as adding a timer 358 # do something such as adding a timer
365 366
366 # this "blocks" (while handling events) till the callback 367 # this "blocks" (while handling events) till the callback
367 # calls send 368 # calls send
368 $result_ready->recv; 369 $result_ready->recv;
369 370
371Example: wait for a timer, but take advantage of the fact that
372condition variables are also code references.
373
374 my $done = AnyEvent->condvar;
375 my $delay = AnyEvent->timer (after => 5, cb => $done);
376 $done->recv;
377
370=head3 METHODS FOR PRODUCERS 378=head3 METHODS FOR PRODUCERS
371 379
372These methods should only be used by the producing side, i.e. the 380These methods should only be used by the producing side, i.e. the
373code/module that eventually sends the signal. Note that it is also 381code/module that eventually sends the signal. Note that it is also
374the producer side which creates the condvar in most cases, but it isn't 382the producer side which creates the condvar in most cases, but it isn't
385If a callback has been set on the condition variable, it is called 393If a callback has been set on the condition variable, it is called
386immediately from within send. 394immediately from within send.
387 395
388Any arguments passed to the C<send> call will be returned by all 396Any arguments passed to the C<send> call will be returned by all
389future C<< ->recv >> calls. 397future C<< ->recv >> calls.
398
399Condition variables are overloaded so one can call them directly (as a
400code reference). Calling them directly is the same as calling C<send>.
390 401
391=item $cv->croak ($error) 402=item $cv->croak ($error)
392 403
393Similar to send, but causes all call's to C<< ->recv >> to invoke 404Similar to send, but causes all call's to C<< ->recv >> to invoke
394C<Carp::croak> with the given error message/object/scalar. 405C<Carp::croak> with the given error message/object/scalar.
443doesn't execute once). 454doesn't execute once).
444 455
445This is the general pattern when you "fan out" into multiple subrequests: 456This is the general pattern when you "fan out" into multiple subrequests:
446use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 457use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447is called at least once, and then, for each subrequest you start, call 458is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>. 459C<begin> and for each subrequest you finish, call C<end>.
449 460
450=back 461=back
451 462
452=head3 METHODS FOR CONSUMERS 463=head3 METHODS FOR CONSUMERS
453 464
475(programs might want to do that to stay interactive), so I<if you are 486(programs might want to do that to stay interactive), so I<if you are
476using this from a module, never require a blocking wait>, but let the 487using this from a module, never require a blocking wait>, but let the
477caller decide whether the call will block or not (for example, by coupling 488caller decide whether the call will block or not (for example, by coupling
478condition variables with some kind of request results and supporting 489condition variables with some kind of request results and supporting
479callbacks so the caller knows that getting the result will not block, 490callbacks so the caller knows that getting the result will not block,
480while still suppporting blocking waits if the caller so desires). 491while still supporting blocking waits if the caller so desires).
481 492
482Another reason I<never> to C<< ->recv >> in a module is that you cannot 493Another reason I<never> to C<< ->recv >> in a module is that you cannot
483sensibly have two C<< ->recv >>'s in parallel, as that would require 494sensibly have two C<< ->recv >>'s in parallel, as that would require
484multiple interpreters or coroutines/threads, none of which C<AnyEvent> 495multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485can supply. 496can supply.
696no warnings; 707no warnings;
697use strict; 708use strict;
698 709
699use Carp; 710use Carp;
700 711
701our $VERSION = '3.6'; 712our $VERSION = '4.03';
702our $MODEL; 713our $MODEL;
703 714
704our $AUTOLOAD; 715our $AUTOLOAD;
705our @ISA; 716our @ISA;
706 717
914 925
915our @ISA = AnyEvent::CondVar::Base::; 926our @ISA = AnyEvent::CondVar::Base::;
916 927
917package AnyEvent::CondVar::Base; 928package AnyEvent::CondVar::Base;
918 929
930use overload
931 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
932 fallback => 1;
933
919sub _send { 934sub _send {
920 # nop 935 # nop
921} 936}
922 937
923sub send { 938sub send {
1029model it chooses. 1044model it chooses.
1030 1045
1031=item C<PERL_ANYEVENT_MODEL> 1046=item C<PERL_ANYEVENT_MODEL>
1032 1047
1033This can be used to specify the event model to be used by AnyEvent, before 1048This can be used to specify the event model to be used by AnyEvent, before
1034autodetection and -probing kicks in. It must be a string consisting 1049auto detection and -probing kicks in. It must be a string consisting
1035entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1050entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1036and the resulting module name is loaded and if the load was successful, 1051and the resulting module name is loaded and if the load was successful,
1037used as event model. If it fails to load AnyEvent will proceed with 1052used as event model. If it fails to load AnyEvent will proceed with
1038autodetection and -probing. 1053auto detection and -probing.
1039 1054
1040This functionality might change in future versions. 1055This functionality might change in future versions.
1041 1056
1042For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1057For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1043could start your program like this: 1058could start your program like this:
1046 1061
1047=item C<PERL_ANYEVENT_PROTOCOLS> 1062=item C<PERL_ANYEVENT_PROTOCOLS>
1048 1063
1049Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences 1064Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1050for IPv4 or IPv6. The default is unspecified (and might change, or be the result 1065for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1051of autoprobing). 1066of auto probing).
1052 1067
1053Must be set to a comma-separated list of protocols or address families, 1068Must be set to a comma-separated list of protocols or address families,
1054current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be 1069current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1055used, and preference will be given to protocols mentioned earlier in the 1070used, and preference will be given to protocols mentioned earlier in the
1056list. 1071list.
1060small, as the program has to handle connection errors already- 1075small, as the program has to handle connection errors already-
1061 1076
1062Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, 1077Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1063but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> 1078but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1064- only support IPv4, never try to resolve or contact IPv6 1079- only support IPv4, never try to resolve or contact IPv6
1065addressses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or 1080addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1066IPv6, but prefer IPv6 over IPv4. 1081IPv6, but prefer IPv6 over IPv4.
1067 1082
1068=item C<PERL_ANYEVENT_EDNS0> 1083=item C<PERL_ANYEVENT_EDNS0>
1069 1084
1070Used by L<AnyEvent::DNS> to decide wether to use the EDNS0 extension 1085Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1071for DNS. This extension is generally useful to reduce DNS traffic, but 1086for DNS. This extension is generally useful to reduce DNS traffic, but
1072some (broken) firewalls drop such DNS packets, which is why it is off by 1087some (broken) firewalls drop such DNS packets, which is why it is off by
1073default. 1088default.
1074 1089
1075Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce 1090Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1167 syswrite $txn->{fh}, $txn->{request} 1182 syswrite $txn->{fh}, $txn->{request}
1168 or die "connection or write error"; 1183 or die "connection or write error";
1169 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1184 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1170 1185
1171Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1186Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1172result and signals any possible waiters that the request ahs finished: 1187result and signals any possible waiters that the request has finished:
1173 1188
1174 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1189 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1175 1190
1176 if (end-of-file or data complete) { 1191 if (end-of-file or data complete) {
1177 $txn->{result} = $txn->{buf}; 1192 $txn->{result} = $txn->{buf};
1185 1200
1186 $txn->{finished}->recv; 1201 $txn->{finished}->recv;
1187 return $txn->{result}; 1202 return $txn->{result};
1188 1203
1189The actual code goes further and collects all errors (C<die>s, exceptions) 1204The actual code goes further and collects all errors (C<die>s, exceptions)
1190that occured during request processing. The C<result> method detects 1205that occurred during request processing. The C<result> method detects
1191whether an exception as thrown (it is stored inside the $txn object) 1206whether an exception as thrown (it is stored inside the $txn object)
1192and just throws the exception, which means connection errors and other 1207and just throws the exception, which means connection errors and other
1193problems get reported tot he code that tries to use the result, not in a 1208problems get reported tot he code that tries to use the result, not in a
1194random callback. 1209random callback.
1195 1210
1241of various event loops I prepared some benchmarks. 1256of various event loops I prepared some benchmarks.
1242 1257
1243=head2 BENCHMARKING ANYEVENT OVERHEAD 1258=head2 BENCHMARKING ANYEVENT OVERHEAD
1244 1259
1245Here is a benchmark of various supported event models used natively and 1260Here is a benchmark of various supported event models used natively and
1246through anyevent. The benchmark creates a lot of timers (with a zero 1261through AnyEvent. The benchmark creates a lot of timers (with a zero
1247timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1262timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1248which it is), lets them fire exactly once and destroys them again. 1263which it is), lets them fire exactly once and destroys them again.
1249 1264
1250Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1265Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1251distribution. 1266distribution.
1374 1389
1375=back 1390=back
1376 1391
1377=head2 BENCHMARKING THE LARGE SERVER CASE 1392=head2 BENCHMARKING THE LARGE SERVER CASE
1378 1393
1379This benchmark atcually benchmarks the event loop itself. It works by 1394This benchmark actually benchmarks the event loop itself. It works by
1380creating a number of "servers": each server consists of a socketpair, a 1395creating a number of "servers": each server consists of a socket pair, a
1381timeout watcher that gets reset on activity (but never fires), and an I/O 1396timeout watcher that gets reset on activity (but never fires), and an I/O
1382watcher waiting for input on one side of the socket. Each time the socket 1397watcher waiting for input on one side of the socket. Each time the socket
1383watcher reads a byte it will write that byte to a random other "server". 1398watcher reads a byte it will write that byte to a random other "server".
1384 1399
1385The effect is that there will be a lot of I/O watchers, only part of which 1400The effect is that there will be a lot of I/O watchers, only part of which
1386are active at any one point (so there is a constant number of active 1401are active at any one point (so there is a constant number of active
1387fds for each loop iterstaion, but which fds these are is random). The 1402fds for each loop iteration, but which fds these are is random). The
1388timeout is reset each time something is read because that reflects how 1403timeout is reset each time something is read because that reflects how
1389most timeouts work (and puts extra pressure on the event loops). 1404most timeouts work (and puts extra pressure on the event loops).
1390 1405
1391In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1406In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1392(1%) are active. This mirrors the activity of large servers with many 1407(1%) are active. This mirrors the activity of large servers with many
1393connections, most of which are idle at any one point in time. 1408connections, most of which are idle at any one point in time.
1394 1409
1395Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1410Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1396distribution. 1411distribution.
1398=head3 Explanation of the columns 1413=head3 Explanation of the columns
1399 1414
1400I<sockets> is the number of sockets, and twice the number of "servers" (as 1415I<sockets> is the number of sockets, and twice the number of "servers" (as
1401each server has a read and write socket end). 1416each server has a read and write socket end).
1402 1417
1403I<create> is the time it takes to create a socketpair (which is 1418I<create> is the time it takes to create a socket pair (which is
1404nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1419nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1405 1420
1406I<request>, the most important value, is the time it takes to handle a 1421I<request>, the most important value, is the time it takes to handle a
1407single "request", that is, reading the token from the pipe and forwarding 1422single "request", that is, reading the token from the pipe and forwarding
1408it to another server. This includes deleting the old timeout and creating 1423it to another server. This includes deleting the old timeout and creating
1481speed most when you have lots of watchers, not when you only have a few of 1496speed most when you have lots of watchers, not when you only have a few of
1482them). 1497them).
1483 1498
1484EV is again fastest. 1499EV is again fastest.
1485 1500
1486Perl again comes second. It is noticably faster than the C-based event 1501Perl again comes second. It is noticeably faster than the C-based event
1487loops Event and Glib, although the difference is too small to really 1502loops Event and Glib, although the difference is too small to really
1488matter. 1503matter.
1489 1504
1490POE also performs much better in this case, but is is still far behind the 1505POE also performs much better in this case, but is is still far behind the
1491others. 1506others.

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines