… | |
… | |
57 | as those use one of the supported event loops. It is trivial to add new |
57 | as those use one of the supported event loops. It is trivial to add new |
58 | event loops to AnyEvent, too, so it is future-proof). |
58 | event loops to AnyEvent, too, so it is future-proof). |
59 | |
59 | |
60 | In addition to being free of having to use I<the one and only true event |
60 | In addition to being free of having to use I<the one and only true event |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
62 | modules, you get an enourmous amount of code and strict rules you have to |
62 | modules, you get an enormous amount of code and strict rules you have to |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
65 | technically possible. |
65 | technically possible. |
66 | |
66 | |
67 | Of course, if you want lots of policy (this can arguably be somewhat |
67 | Of course, if you want lots of policy (this can arguably be somewhat |
… | |
… | |
108 | |
108 | |
109 | =head1 WATCHERS |
109 | =head1 WATCHERS |
110 | |
110 | |
111 | AnyEvent has the central concept of a I<watcher>, which is an object that |
111 | AnyEvent has the central concept of a I<watcher>, which is an object that |
112 | stores relevant data for each kind of event you are waiting for, such as |
112 | stores relevant data for each kind of event you are waiting for, such as |
113 | the callback to call, the filehandle to watch, etc. |
113 | the callback to call, the file handle to watch, etc. |
114 | |
114 | |
115 | These watchers are normal Perl objects with normal Perl lifetime. After |
115 | These watchers are normal Perl objects with normal Perl lifetime. After |
116 | creating a watcher it will immediately "watch" for events and invoke the |
116 | creating a watcher it will immediately "watch" for events and invoke the |
117 | callback when the event occurs (of course, only when the event model |
117 | callback when the event occurs (of course, only when the event model |
118 | is in control). |
118 | is in control). |
… | |
… | |
237 | |
237 | |
238 | Although the callback might get passed parameters, their value and |
238 | Although the callback might get passed parameters, their value and |
239 | presence is undefined and you cannot rely on them. Portable AnyEvent |
239 | presence is undefined and you cannot rely on them. Portable AnyEvent |
240 | callbacks cannot use arguments passed to signal watcher callbacks. |
240 | callbacks cannot use arguments passed to signal watcher callbacks. |
241 | |
241 | |
242 | Multiple signal occurances can be clumped together into one callback |
242 | Multiple signal occurrences can be clumped together into one callback |
243 | invocation, and callback invocation will be synchronous. synchronous means |
243 | invocation, and callback invocation will be synchronous. Synchronous means |
244 | that it might take a while until the signal gets handled by the process, |
244 | that it might take a while until the signal gets handled by the process, |
245 | but it is guarenteed not to interrupt any other callbacks. |
245 | but it is guaranteed not to interrupt any other callbacks. |
246 | |
246 | |
247 | The main advantage of using these watchers is that you can share a signal |
247 | The main advantage of using these watchers is that you can share a signal |
248 | between multiple watchers. |
248 | between multiple watchers. |
249 | |
249 | |
250 | This watcher might use C<%SIG>, so programs overwriting those signals |
250 | This watcher might use C<%SIG>, so programs overwriting those signals |
… | |
… | |
310 | Condition variables can be created by calling the C<< AnyEvent->condvar |
310 | Condition 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 |
312 | C<cb>, which specifies a callback to be called when the condition variable |
312 | C<cb>, which specifies a callback to be called when the condition variable |
313 | becomes true. |
313 | becomes true. |
314 | |
314 | |
315 | After creation, the conditon variable is "false" until it becomes "true" |
315 | After creation, the condition variable is "false" until it becomes "true" |
316 | by calling the C<send> method. |
316 | by calling the C<send> method (or calling the condition variable as if it |
|
|
317 | were a callback). |
317 | |
318 | |
318 | Condition variables are similar to callbacks, except that you can |
319 | Condition variables are similar to callbacks, except that you can |
319 | optionally wait for them. They can also be called merge points - points |
320 | optionally wait for them. They can also be called merge points - points |
320 | in time where multiple outstandign events have been processed. And yet |
321 | in time where multiple outstanding events have been processed. And yet |
321 | another way to call them is transations - each condition variable can be |
322 | another way to call them is transactions - each condition variable can be |
322 | used to represent a transaction, which finishes at some point and delivers |
323 | used to represent a transaction, which finishes at some point and delivers |
323 | a result. |
324 | a result. |
324 | |
325 | |
325 | Condition variables are very useful to signal that something has finished, |
326 | Condition variables are very useful to signal that something has finished, |
326 | for example, if you write a module that does asynchronous http requests, |
327 | for example, if you write a module that does asynchronous http requests, |
… | |
… | |
332 | you can block your main program until an event occurs - for example, you |
333 | you can block your main program until an event occurs - for example, you |
333 | could C<< ->recv >> in your main program until the user clicks the Quit |
334 | could C<< ->recv >> in your main program until the user clicks the Quit |
334 | button of your app, which would C<< ->send >> the "quit" event. |
335 | button of your app, which would C<< ->send >> the "quit" event. |
335 | |
336 | |
336 | Note that condition variables recurse into the event loop - if you have |
337 | Note that condition variables recurse into the event loop - if you have |
337 | two pieces of code that call C<< ->recv >> in a round-robbin fashion, you |
338 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
338 | lose. Therefore, condition variables are good to export to your caller, but |
339 | lose. Therefore, condition variables are good to export to your caller, but |
339 | you should avoid making a blocking wait yourself, at least in callbacks, |
340 | you should avoid making a blocking wait yourself, at least in callbacks, |
340 | as this asks for trouble. |
341 | as this asks for trouble. |
341 | |
342 | |
342 | Condition variables are represented by hash refs in perl, and the keys |
343 | Condition variables are represented by hash refs in perl, and the keys |
… | |
… | |
347 | |
348 | |
348 | There are two "sides" to a condition variable - the "producer side" which |
349 | There are two "sides" to a condition variable - the "producer side" which |
349 | eventually calls C<< -> send >>, and the "consumer side", which waits |
350 | eventually calls C<< -> send >>, and the "consumer side", which waits |
350 | for the send to occur. |
351 | for the send to occur. |
351 | |
352 | |
352 | Example: |
353 | Example: 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 | |
|
|
371 | Example: wait for a timer, but take advantage of the fact that |
|
|
372 | condition 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 | |
372 | These methods should only be used by the producing side, i.e. the |
380 | These methods should only be used by the producing side, i.e. the |
373 | code/module that eventually sends the signal. Note that it is also |
381 | code/module that eventually sends the signal. Note that it is also |
374 | the producer side which creates the condvar in most cases, but it isn't |
382 | the producer side which creates the condvar in most cases, but it isn't |
… | |
… | |
385 | If a callback has been set on the condition variable, it is called |
393 | If a callback has been set on the condition variable, it is called |
386 | immediately from within send. |
394 | immediately from within send. |
387 | |
395 | |
388 | Any arguments passed to the C<send> call will be returned by all |
396 | Any arguments passed to the C<send> call will be returned by all |
389 | future C<< ->recv >> calls. |
397 | future C<< ->recv >> calls. |
|
|
398 | |
|
|
399 | Condition variables are overloaded so one can call them directly (as a |
|
|
400 | code 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 | |
393 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
404 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
394 | C<Carp::croak> with the given error message/object/scalar. |
405 | C<Carp::croak> with the given error message/object/scalar. |
… | |
… | |
443 | doesn't execute once). |
454 | doesn't execute once). |
444 | |
455 | |
445 | This is the general pattern when you "fan out" into multiple subrequests: |
456 | This is the general pattern when you "fan out" into multiple subrequests: |
446 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
457 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
447 | is called at least once, and then, for each subrequest you start, call |
458 | is called at least once, and then, for each subrequest you start, call |
448 | C<begin> and for eahc subrequest you finish, call C<end>. |
459 | C<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 |
476 | using this from a module, never require a blocking wait>, but let the |
487 | using this from a module, never require a blocking wait>, but let the |
477 | caller decide whether the call will block or not (for example, by coupling |
488 | caller decide whether the call will block or not (for example, by coupling |
478 | condition variables with some kind of request results and supporting |
489 | condition variables with some kind of request results and supporting |
479 | callbacks so the caller knows that getting the result will not block, |
490 | callbacks so the caller knows that getting the result will not block, |
480 | while still suppporting blocking waits if the caller so desires). |
491 | while still supporting blocking waits if the caller so desires). |
481 | |
492 | |
482 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
493 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
483 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
494 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
495 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
485 | can supply. |
496 | can supply. |
… | |
… | |
696 | no warnings; |
707 | no warnings; |
697 | use strict; |
708 | use strict; |
698 | |
709 | |
699 | use Carp; |
710 | use Carp; |
700 | |
711 | |
701 | our $VERSION = '3.6'; |
712 | our $VERSION = '4.03'; |
702 | our $MODEL; |
713 | our $MODEL; |
703 | |
714 | |
704 | our $AUTOLOAD; |
715 | our $AUTOLOAD; |
705 | our @ISA; |
716 | our @ISA; |
706 | |
717 | |
… | |
… | |
914 | |
925 | |
915 | our @ISA = AnyEvent::CondVar::Base::; |
926 | our @ISA = AnyEvent::CondVar::Base::; |
916 | |
927 | |
917 | package AnyEvent::CondVar::Base; |
928 | package AnyEvent::CondVar::Base; |
918 | |
929 | |
|
|
930 | use overload |
|
|
931 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
932 | fallback => 1; |
|
|
933 | |
919 | sub _send { |
934 | sub _send { |
920 | # nop |
935 | # nop |
921 | } |
936 | } |
922 | |
937 | |
923 | sub send { |
938 | sub send { |
… | |
… | |
1029 | model it chooses. |
1044 | model it chooses. |
1030 | |
1045 | |
1031 | =item C<PERL_ANYEVENT_MODEL> |
1046 | =item C<PERL_ANYEVENT_MODEL> |
1032 | |
1047 | |
1033 | This can be used to specify the event model to be used by AnyEvent, before |
1048 | This can be used to specify the event model to be used by AnyEvent, before |
1034 | autodetection and -probing kicks in. It must be a string consisting |
1049 | auto detection and -probing kicks in. It must be a string consisting |
1035 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
1050 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
1036 | and the resulting module name is loaded and if the load was successful, |
1051 | and the resulting module name is loaded and if the load was successful, |
1037 | used as event model. If it fails to load AnyEvent will proceed with |
1052 | used as event model. If it fails to load AnyEvent will proceed with |
1038 | autodetection and -probing. |
1053 | auto detection and -probing. |
1039 | |
1054 | |
1040 | This functionality might change in future versions. |
1055 | This functionality might change in future versions. |
1041 | |
1056 | |
1042 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
1057 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
1043 | could start your program like this: |
1058 | could start your program like this: |
… | |
… | |
1046 | |
1061 | |
1047 | =item C<PERL_ANYEVENT_PROTOCOLS> |
1062 | =item C<PERL_ANYEVENT_PROTOCOLS> |
1048 | |
1063 | |
1049 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
1064 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
1050 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
1065 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
1051 | of autoprobing). |
1066 | of auto probing). |
1052 | |
1067 | |
1053 | Must be set to a comma-separated list of protocols or address families, |
1068 | Must be set to a comma-separated list of protocols or address families, |
1054 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
1069 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
1055 | used, and preference will be given to protocols mentioned earlier in the |
1070 | used, and preference will be given to protocols mentioned earlier in the |
1056 | list. |
1071 | list. |
1057 | |
1072 | |
|
|
1073 | This variable can effectively be used for denial-of-service attacks |
|
|
1074 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1075 | small, as the program has to handle connection errors already- |
|
|
1076 | |
1058 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
1077 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
1059 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
1078 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
1060 | - only support IPv4, never try to resolve or contact IPv6 |
1079 | - only support IPv4, never try to resolve or contact IPv6 |
1061 | addressses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
1080 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
1062 | IPv6, but prefer IPv6 over IPv4. |
1081 | IPv6, but prefer IPv6 over IPv4. |
|
|
1082 | |
|
|
1083 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1084 | |
|
|
1085 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1086 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1087 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1088 | default. |
|
|
1089 | |
|
|
1090 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1091 | EDNS0 in its DNS requests. |
1063 | |
1092 | |
1064 | =back |
1093 | =back |
1065 | |
1094 | |
1066 | =head1 EXAMPLE PROGRAM |
1095 | =head1 EXAMPLE PROGRAM |
1067 | |
1096 | |
… | |
… | |
1153 | syswrite $txn->{fh}, $txn->{request} |
1182 | syswrite $txn->{fh}, $txn->{request} |
1154 | or die "connection or write error"; |
1183 | or die "connection or write error"; |
1155 | $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 }); |
1156 | |
1185 | |
1157 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1186 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1158 | result and signals any possible waiters that the request ahs finished: |
1187 | result and signals any possible waiters that the request has finished: |
1159 | |
1188 | |
1160 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1189 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1161 | |
1190 | |
1162 | if (end-of-file or data complete) { |
1191 | if (end-of-file or data complete) { |
1163 | $txn->{result} = $txn->{buf}; |
1192 | $txn->{result} = $txn->{buf}; |
… | |
… | |
1171 | |
1200 | |
1172 | $txn->{finished}->recv; |
1201 | $txn->{finished}->recv; |
1173 | return $txn->{result}; |
1202 | return $txn->{result}; |
1174 | |
1203 | |
1175 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1204 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1176 | that occured during request processing. The C<result> method detects |
1205 | that occurred during request processing. The C<result> method detects |
1177 | whether an exception as thrown (it is stored inside the $txn object) |
1206 | whether an exception as thrown (it is stored inside the $txn object) |
1178 | and just throws the exception, which means connection errors and other |
1207 | and just throws the exception, which means connection errors and other |
1179 | problems get reported tot he code that tries to use the result, not in a |
1208 | problems get reported tot he code that tries to use the result, not in a |
1180 | random callback. |
1209 | random callback. |
1181 | |
1210 | |
… | |
… | |
1227 | of various event loops I prepared some benchmarks. |
1256 | of various event loops I prepared some benchmarks. |
1228 | |
1257 | |
1229 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
1258 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
1230 | |
1259 | |
1231 | Here is a benchmark of various supported event models used natively and |
1260 | Here is a benchmark of various supported event models used natively and |
1232 | through anyevent. The benchmark creates a lot of timers (with a zero |
1261 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1233 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1262 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1234 | which it is), lets them fire exactly once and destroys them again. |
1263 | which it is), lets them fire exactly once and destroys them again. |
1235 | |
1264 | |
1236 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
1265 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
1237 | distribution. |
1266 | distribution. |
… | |
… | |
1360 | |
1389 | |
1361 | =back |
1390 | =back |
1362 | |
1391 | |
1363 | =head2 BENCHMARKING THE LARGE SERVER CASE |
1392 | =head2 BENCHMARKING THE LARGE SERVER CASE |
1364 | |
1393 | |
1365 | This benchmark atcually benchmarks the event loop itself. It works by |
1394 | This benchmark actually benchmarks the event loop itself. It works by |
1366 | creating a number of "servers": each server consists of a socketpair, a |
1395 | creating a number of "servers": each server consists of a socket pair, a |
1367 | timeout watcher that gets reset on activity (but never fires), and an I/O |
1396 | timeout watcher that gets reset on activity (but never fires), and an I/O |
1368 | watcher waiting for input on one side of the socket. Each time the socket |
1397 | watcher waiting for input on one side of the socket. Each time the socket |
1369 | watcher reads a byte it will write that byte to a random other "server". |
1398 | watcher reads a byte it will write that byte to a random other "server". |
1370 | |
1399 | |
1371 | The effect is that there will be a lot of I/O watchers, only part of which |
1400 | The effect is that there will be a lot of I/O watchers, only part of which |
1372 | are active at any one point (so there is a constant number of active |
1401 | are active at any one point (so there is a constant number of active |
1373 | fds for each loop iterstaion, but which fds these are is random). The |
1402 | fds for each loop iteration, but which fds these are is random). The |
1374 | timeout is reset each time something is read because that reflects how |
1403 | timeout is reset each time something is read because that reflects how |
1375 | most timeouts work (and puts extra pressure on the event loops). |
1404 | most timeouts work (and puts extra pressure on the event loops). |
1376 | |
1405 | |
1377 | In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 |
1406 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
1378 | (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 |
1379 | connections, most of which are idle at any one point in time. |
1408 | connections, most of which are idle at any one point in time. |
1380 | |
1409 | |
1381 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
1410 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
1382 | distribution. |
1411 | distribution. |
… | |
… | |
1384 | =head3 Explanation of the columns |
1413 | =head3 Explanation of the columns |
1385 | |
1414 | |
1386 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
1415 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
1387 | each server has a read and write socket end). |
1416 | each server has a read and write socket end). |
1388 | |
1417 | |
1389 | I<create> is the time it takes to create a socketpair (which is |
1418 | I<create> is the time it takes to create a socket pair (which is |
1390 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
1419 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
1391 | |
1420 | |
1392 | I<request>, the most important value, is the time it takes to handle a |
1421 | I<request>, the most important value, is the time it takes to handle a |
1393 | single "request", that is, reading the token from the pipe and forwarding |
1422 | single "request", that is, reading the token from the pipe and forwarding |
1394 | it to another server. This includes deleting the old timeout and creating |
1423 | it to another server. This includes deleting the old timeout and creating |
… | |
… | |
1467 | speed most when you have lots of watchers, not when you only have a few of |
1496 | speed most when you have lots of watchers, not when you only have a few of |
1468 | them). |
1497 | them). |
1469 | |
1498 | |
1470 | EV is again fastest. |
1499 | EV is again fastest. |
1471 | |
1500 | |
1472 | Perl again comes second. It is noticably faster than the C-based event |
1501 | Perl again comes second. It is noticeably faster than the C-based event |
1473 | loops Event and Glib, although the difference is too small to really |
1502 | loops Event and Glib, although the difference is too small to really |
1474 | matter. |
1503 | matter. |
1475 | |
1504 | |
1476 | POE also performs much better in this case, but is is still far behind the |
1505 | POE also performs much better in this case, but is is still far behind the |
1477 | others. |
1506 | others. |