… | |
… | |
503 | |
503 | |
504 | =head2 IDLE WATCHERS |
504 | =head2 IDLE WATCHERS |
505 | |
505 | |
506 | $w = AnyEvent->idle (cb => <callback>); |
506 | $w = AnyEvent->idle (cb => <callback>); |
507 | |
507 | |
508 | Sometimes there is a need to do something, but it is not so important |
508 | Repeatedly invoke the callback after the process becomes idle, until |
509 | to do it instantly, but only when there is nothing better to do. This |
509 | either the watcher is destroyed or new events have been detected. |
510 | "nothing better to do" is usually defined to be "no other events need |
|
|
511 | attention by the event loop". |
|
|
512 | |
510 | |
513 | Idle watchers ideally get invoked when the event loop has nothing |
511 | Idle watchers are useful when there is a need to do something, but it |
514 | better to do, just before it would block the process to wait for new |
512 | is not so important (or wise) to do it instantly. The callback will be |
515 | events. Instead of blocking, the idle watcher is invoked. |
513 | invoked only when there is "nothing better to do", which is usually |
|
|
514 | defined as "all outstanding events have been handled and no new events |
|
|
515 | have been detected". That means that idle watchers ideally get invoked |
|
|
516 | when the event loop has just polled for new events but none have been |
|
|
517 | detected. Instead of blocking to wait for more events, the idle watchers |
|
|
518 | will be invoked. |
516 | |
519 | |
517 | Most event loops unfortunately do not really support idle watchers (only |
520 | Unfortunately, most event loops do not really support idle watchers (only |
518 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
521 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
519 | will simply call the callback "from time to time". |
522 | will simply call the callback "from time to time". |
520 | |
523 | |
521 | Example: read lines from STDIN, but only process them when the |
524 | Example: read lines from STDIN, but only process them when the |
522 | program is otherwise idle: |
525 | program is otherwise idle: |
… | |
… | |
966 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
969 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
967 | if it is defined then the event loop has already been detected, and the |
970 | if it is defined then the event loop has already been detected, and the |
968 | array will be ignored. |
971 | array will be ignored. |
969 | |
972 | |
970 | Best use C<AnyEvent::post_detect { BLOCK }> when your application allows |
973 | Best use C<AnyEvent::post_detect { BLOCK }> when your application allows |
971 | it,as it takes care of these details. |
974 | it, as it takes care of these details. |
972 | |
975 | |
973 | This variable is mainly useful for modules that can do something useful |
976 | This variable is mainly useful for modules that can do something useful |
974 | when AnyEvent is used and thus want to know when it is initialised, but do |
977 | when AnyEvent is used and thus want to know when it is initialised, but do |
975 | not need to even load it by default. This array provides the means to hook |
978 | not need to even load it by default. This array provides the means to hook |
976 | into AnyEvent passively, without loading it. |
979 | into AnyEvent passively, without loading it. |
|
|
980 | |
|
|
981 | Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used |
|
|
982 | together, you could put this into Coro (this is the actual code used by |
|
|
983 | Coro to accomplish this): |
|
|
984 | |
|
|
985 | if (defined $AnyEvent::MODEL) { |
|
|
986 | # AnyEvent already initialised, so load Coro::AnyEvent |
|
|
987 | require Coro::AnyEvent; |
|
|
988 | } else { |
|
|
989 | # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent |
|
|
990 | # as soon as it is |
|
|
991 | push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; |
|
|
992 | } |
977 | |
993 | |
978 | =back |
994 | =back |
979 | |
995 | |
980 | =head1 WHAT TO DO IN A MODULE |
996 | =head1 WHAT TO DO IN A MODULE |
981 | |
997 | |
… | |
… | |
1131 | package AnyEvent; |
1147 | package AnyEvent; |
1132 | |
1148 | |
1133 | # basically a tuned-down version of common::sense |
1149 | # basically a tuned-down version of common::sense |
1134 | sub common_sense { |
1150 | sub common_sense { |
1135 | # from common:.sense 1.0 |
1151 | # from common:.sense 1.0 |
1136 | ${^WARNING_BITS} = "\xfc\x3f\xf3\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03"; |
1152 | ${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x00"; |
1137 | # use strict vars subs |
1153 | # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl) |
1138 | $^H |= 0x00000600; |
1154 | $^H |= 0x00000600; |
1139 | } |
1155 | } |
1140 | |
1156 | |
1141 | BEGIN { AnyEvent::common_sense } |
1157 | BEGIN { AnyEvent::common_sense } |
1142 | |
1158 | |
1143 | use Carp (); |
1159 | use Carp (); |
1144 | |
1160 | |
1145 | our $VERSION = '5.21'; |
1161 | our $VERSION = '5.23'; |
1146 | our $MODEL; |
1162 | our $MODEL; |
1147 | |
1163 | |
1148 | our $AUTOLOAD; |
1164 | our $AUTOLOAD; |
1149 | our @ISA; |
1165 | our @ISA; |
1150 | |
1166 | |
… | |
… | |
2448 | it's built-in modules) are required to use it. |
2464 | it's built-in modules) are required to use it. |
2449 | |
2465 | |
2450 | That does not mean that AnyEvent won't take advantage of some additional |
2466 | That does not mean that AnyEvent won't take advantage of some additional |
2451 | modules if they are installed. |
2467 | modules if they are installed. |
2452 | |
2468 | |
2453 | This section epxlains which additional modules will be used, and how they |
2469 | This section explains which additional modules will be used, and how they |
2454 | affect AnyEvent's operation. |
2470 | affect AnyEvent's operation. |
2455 | |
2471 | |
2456 | =over 4 |
2472 | =over 4 |
2457 | |
2473 | |
2458 | =item L<Async::Interrupt> |
2474 | =item L<Async::Interrupt> |
… | |
… | |
2464 | catch the signals) with some delay (default is 10 seconds, look for |
2480 | catch the signals) with some delay (default is 10 seconds, look for |
2465 | C<$AnyEvent::MAX_SIGNAL_LATENCY>). |
2481 | C<$AnyEvent::MAX_SIGNAL_LATENCY>). |
2466 | |
2482 | |
2467 | If this module is available, then it will be used to implement signal |
2483 | If this module is available, then it will be used to implement signal |
2468 | catching, which means that signals will not be delayed, and the event loop |
2484 | catching, which means that signals will not be delayed, and the event loop |
2469 | will not be interrupted regularly, which is more efficient (And good for |
2485 | will not be interrupted regularly, which is more efficient (and good for |
2470 | battery life on laptops). |
2486 | battery life on laptops). |
2471 | |
2487 | |
2472 | This affects not just the pure-perl event loop, but also other event loops |
2488 | This affects not just the pure-perl event loop, but also other event loops |
2473 | that have no signal handling on their own (e.g. Glib, Tk, Qt). |
2489 | that have no signal handling on their own (e.g. Glib, Tk, Qt). |
2474 | |
2490 | |
… | |
… | |
2521 | |
2537 | |
2522 | |
2538 | |
2523 | =head1 FORK |
2539 | =head1 FORK |
2524 | |
2540 | |
2525 | Most event libraries are not fork-safe. The ones who are usually are |
2541 | Most event libraries are not fork-safe. The ones who are usually are |
2526 | because they rely on inefficient but fork-safe C<select> or C<poll> |
2542 | because they rely on inefficient but fork-safe C<select> or C<poll> calls |
2527 | calls. Only L<EV> is fully fork-aware. |
2543 | - higher performance APIs such as BSD's kqueue or the dreaded Linux epoll |
|
|
2544 | are usually badly thought-out hacks that are incompatible with fork in |
|
|
2545 | one way or another. Only L<EV> is fully fork-aware and ensures that you |
|
|
2546 | continue event-processing in both parent and child (or both, if you know |
|
|
2547 | what you are doing). |
|
|
2548 | |
|
|
2549 | This means that, in general, you cannot fork and do event processing in |
|
|
2550 | the child if the event library was initialised before the fork (which |
|
|
2551 | usually happens when the first AnyEvent watcher is created, or the library |
|
|
2552 | is loaded). |
2528 | |
2553 | |
2529 | If you have to fork, you must either do so I<before> creating your first |
2554 | If you have to fork, you must either do so I<before> creating your first |
2530 | watcher OR you must not use AnyEvent at all in the child OR you must do |
2555 | watcher OR you must not use AnyEvent at all in the child OR you must do |
2531 | something completely out of the scope of AnyEvent. |
2556 | something completely out of the scope of AnyEvent. |
|
|
2557 | |
|
|
2558 | The problem of doing event processing in the parent I<and> the child |
|
|
2559 | is much more complicated: even for backends that I<are> fork-aware or |
|
|
2560 | fork-safe, their behaviour is not usually what you want: fork clones all |
|
|
2561 | watchers, that means all timers, I/O watchers etc. are active in both |
|
|
2562 | parent and child, which is almost never what you want. USing C<exec> |
|
|
2563 | to start worker children from some kind of manage rprocess is usually |
|
|
2564 | preferred, because it is much easier and cleaner, at the expense of having |
|
|
2565 | to have another binary. |
2532 | |
2566 | |
2533 | |
2567 | |
2534 | =head1 SECURITY CONSIDERATIONS |
2568 | =head1 SECURITY CONSIDERATIONS |
2535 | |
2569 | |
2536 | AnyEvent can be forced to load any event model via |
2570 | AnyEvent can be forced to load any event model via |