1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - events independent of event loop implementation |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
5 | event loops. |
5 | event loops. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
… | |
… | |
37 | |
37 | |
38 | INTRODUCTION/TUTORIAL |
38 | INTRODUCTION/TUTORIAL |
39 | This manpage is mainly a reference manual. If you are interested in a |
39 | This manpage is mainly a reference manual. If you are interested in a |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
41 | manpage. |
41 | manpage. |
|
|
42 | |
|
|
43 | SUPPORT |
|
|
44 | There is a mailinglist for discussing all things AnyEvent, and an IRC |
|
|
45 | channel, too. |
|
|
46 | |
|
|
47 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
|
|
48 | Respository, at <http://anyevent.schmorp.de>, for more info. |
42 | |
49 | |
43 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
50 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
44 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
51 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
45 | nowadays. So what is different about AnyEvent? |
52 | nowadays. So what is different about AnyEvent? |
46 | |
53 | |
… | |
… | |
350 | invocation, and callback invocation will be synchronous. Synchronous |
357 | invocation, and callback invocation will be synchronous. Synchronous |
351 | means that it might take a while until the signal gets handled by the |
358 | means that it might take a while until the signal gets handled by the |
352 | process, but it is guaranteed not to interrupt any other callbacks. |
359 | process, but it is guaranteed not to interrupt any other callbacks. |
353 | |
360 | |
354 | The main advantage of using these watchers is that you can share a |
361 | The main advantage of using these watchers is that you can share a |
355 | signal between multiple watchers. |
362 | signal between multiple watchers, and AnyEvent will ensure that signals |
|
|
363 | will not interrupt your program at bad times. |
356 | |
364 | |
357 | This watcher might use %SIG, so programs overwriting those signals |
365 | This watcher might use %SIG (depending on the event loop used), so |
358 | directly will likely not work correctly. |
366 | programs overwriting those signals directly will likely not work |
|
|
367 | correctly. |
359 | |
368 | |
360 | Example: exit on SIGINT |
369 | Example: exit on SIGINT |
361 | |
370 | |
362 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
371 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
372 | |
|
|
373 | Signal Races, Delays and Workarounds |
|
|
374 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
|
|
375 | callbacks to signals in a generic way, which is a pity, as you cannot do |
|
|
376 | race-free signal handling in perl. AnyEvent will try to do it's best, |
|
|
377 | but in some cases, signals will be delayed. The maximum time a signal |
|
|
378 | might be delayed is specified in $AnyEvent::MAX_SIGNAL_LATENCY (default: |
|
|
379 | 10 seconds). This variable can be changed only before the first signal |
|
|
380 | watcher is created, and should be left alone otherwise. Higher values |
|
|
381 | will cause fewer spurious wake-ups, which is better for power and CPU |
|
|
382 | saving. All these problems can be avoided by installing the optional |
|
|
383 | Async::Interrupt module. This will not work with inherently broken event |
|
|
384 | loops such as Event or Event::Lib (and not with POE currently, as POE |
|
|
385 | does it's own workaround with one-second latency). With those, you just |
|
|
386 | have to suffer the delays. |
363 | |
387 | |
364 | CHILD PROCESS WATCHERS |
388 | CHILD PROCESS WATCHERS |
365 | You can also watch on a child process exit and catch its exit status. |
389 | You can also watch on a child process exit and catch its exit status. |
366 | |
390 | |
367 | The child process is specified by the "pid" argument (if set to 0, it |
391 | The child process is specified by the "pid" argument (if set to 0, it |
… | |
… | |
390 | of when you start the watcher. |
414 | of when you start the watcher. |
391 | |
415 | |
392 | This means you cannot create a child watcher as the very first thing in |
416 | This means you cannot create a child watcher as the very first thing in |
393 | an AnyEvent program, you *have* to create at least one watcher before |
417 | an AnyEvent program, you *have* to create at least one watcher before |
394 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
418 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
|
|
419 | |
|
|
420 | As most event loops do not support waiting for child events, they will |
|
|
421 | be emulated by AnyEvent in most cases, in which the latency and race |
|
|
422 | problems mentioned in the description of signal watchers apply. |
395 | |
423 | |
396 | Example: fork a process and wait for it |
424 | Example: fork a process and wait for it |
397 | |
425 | |
398 | my $done = AnyEvent->condvar; |
426 | my $done = AnyEvent->condvar; |
399 | |
427 | |
… | |
… | |
473 | Condition variables are similar to callbacks, except that you can |
501 | Condition variables are similar to callbacks, except that you can |
474 | optionally wait for them. They can also be called merge points - points |
502 | optionally wait for them. They can also be called merge points - points |
475 | in time where multiple outstanding events have been processed. And yet |
503 | in time where multiple outstanding events have been processed. And yet |
476 | another way to call them is transactions - each condition variable can |
504 | another way to call them is transactions - each condition variable can |
477 | be used to represent a transaction, which finishes at some point and |
505 | be used to represent a transaction, which finishes at some point and |
478 | delivers a result. |
506 | delivers a result. And yet some people know them as "futures" - a |
|
|
507 | promise to compute/deliver something that you can wait for. |
479 | |
508 | |
480 | Condition variables are very useful to signal that something has |
509 | Condition variables are very useful to signal that something has |
481 | finished, for example, if you write a module that does asynchronous http |
510 | finished, for example, if you write a module that does asynchronous http |
482 | requests, then a condition variable would be the ideal candidate to |
511 | requests, then a condition variable would be the ideal candidate to |
483 | signal the availability of results. The user can either act when the |
512 | signal the availability of results. The user can either act when the |
… | |
… | |
991 | by "PERL_ANYEVENT_MODEL". |
1020 | by "PERL_ANYEVENT_MODEL". |
992 | |
1021 | |
993 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
1022 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
994 | event model it chooses. |
1023 | event model it chooses. |
995 | |
1024 | |
|
|
1025 | When set to 8 or higher, then AnyEvent will report extra information |
|
|
1026 | on which optional modules it loads and how it implements certain |
|
|
1027 | features. |
|
|
1028 | |
996 | "PERL_ANYEVENT_STRICT" |
1029 | "PERL_ANYEVENT_STRICT" |
997 | AnyEvent does not do much argument checking by default, as thorough |
1030 | AnyEvent does not do much argument checking by default, as thorough |
998 | argument checking is very costly. Setting this variable to a true |
1031 | argument checking is very costly. Setting this variable to a true |
999 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1032 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1000 | thoroughly check the arguments passed to most method calls. If it |
1033 | thoroughly check the arguments passed to most method calls. If it |
1001 | finds any problems, it will croak. |
1034 | finds any problems, it will croak. |
1002 | |
1035 | |
1003 | In other words, enables "strict" mode. |
1036 | In other words, enables "strict" mode. |
1004 | |
1037 | |
1005 | Unlike "use strict", it is definitely recommended to keep it off in |
1038 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
1006 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
1039 | is definitely recommended to keep it off in production. Keeping |
|
|
1040 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1007 | while developing programs can be very useful, however. |
1041 | programs can be very useful, however. |
1008 | |
1042 | |
1009 | "PERL_ANYEVENT_MODEL" |
1043 | "PERL_ANYEVENT_MODEL" |
1010 | This can be used to specify the event model to be used by AnyEvent, |
1044 | This can be used to specify the event model to be used by AnyEvent, |
1011 | before auto detection and -probing kicks in. It must be a string |
1045 | before auto detection and -probing kicks in. It must be a string |
1012 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1046 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
1069 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
1103 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
1070 | When neither "ca_file" nor "ca_path" was specified during |
1104 | When neither "ca_file" nor "ca_path" was specified during |
1071 | AnyEvent::TLS context creation, and either of these environment |
1105 | AnyEvent::TLS context creation, and either of these environment |
1072 | variables exist, they will be used to specify CA certificate |
1106 | variables exist, they will be used to specify CA certificate |
1073 | locations instead of a system-dependent default. |
1107 | locations instead of a system-dependent default. |
|
|
1108 | |
|
|
1109 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
|
|
1110 | When these are set to 1, then the respective modules are not loaded. |
|
|
1111 | Mostly good for testing AnyEvent itself. |
1074 | |
1112 | |
1075 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1113 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1076 | This is an advanced topic that you do not normally need to use AnyEvent |
1114 | This is an advanced topic that you do not normally need to use AnyEvent |
1077 | in a module. This section is only of use to event loop authors who want |
1115 | in a module. This section is only of use to event loop authors who want |
1078 | to provide AnyEvent compatibility. |
1116 | to provide AnyEvent compatibility. |
… | |
… | |
1603 | it is that this way, the handler will be restored to defaults on |
1641 | it is that this way, the handler will be restored to defaults on |
1604 | exec. |
1642 | exec. |
1605 | |
1643 | |
1606 | Feel free to install your own handler, or reset it to defaults. |
1644 | Feel free to install your own handler, or reset it to defaults. |
1607 | |
1645 | |
|
|
1646 | RECOMMENDED/OPTIONAL MODULES |
|
|
1647 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
|
|
1648 | it's built-in modules) are required to use it. |
|
|
1649 | |
|
|
1650 | That does not mean that AnyEvent won't take advantage of some additional |
|
|
1651 | modules if they are installed. |
|
|
1652 | |
|
|
1653 | This section epxlains which additional modules will be used, and how |
|
|
1654 | they affect AnyEvent's operetion. |
|
|
1655 | |
|
|
1656 | Async::Interrupt |
|
|
1657 | This slightly arcane module is used to implement fast signal |
|
|
1658 | handling: To my knowledge, there is no way to do completely |
|
|
1659 | race-free and quick signal handling in pure perl. To ensure that |
|
|
1660 | signals still get delivered, AnyEvent will start an interval timer |
|
|
1661 | to wake up perl (and catch the signals) with some delay (default is |
|
|
1662 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1663 | |
|
|
1664 | If this module is available, then it will be used to implement |
|
|
1665 | signal catching, which means that signals will not be delayed, and |
|
|
1666 | the event loop will not be interrupted regularly, which is more |
|
|
1667 | efficient (And good for battery life on laptops). |
|
|
1668 | |
|
|
1669 | This affects not just the pure-perl event loop, but also other event |
|
|
1670 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
|
|
1671 | |
|
|
1672 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
|
|
1673 | natively, and either employ their own workarounds (POE) or use |
|
|
1674 | AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1675 | Installing Async::Interrupt does nothing for those backends. |
|
|
1676 | |
|
|
1677 | EV This module isn't really "optional", as it is simply one of the |
|
|
1678 | backend event loops that AnyEvent can use. However, it is simply the |
|
|
1679 | best event loop available in terms of features, speed and stability: |
|
|
1680 | It supports the AnyEvent API optimally, implements all the watcher |
|
|
1681 | types in XS, does automatic timer adjustments even when no monotonic |
|
|
1682 | clock is available, can take avdantage of advanced kernel interfaces |
|
|
1683 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
|
|
1684 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
|
|
1685 | Glib::EV). |
|
|
1686 | |
|
|
1687 | Guard |
|
|
1688 | The guard module, when used, will be used to implement |
|
|
1689 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
|
|
1690 | uses a lot less memory), but otherwise doesn't affect guard |
|
|
1691 | operation much. It is purely used for performance. |
|
|
1692 | |
|
|
1693 | JSON and JSON::XS |
|
|
1694 | This module is required when you want to read or write JSON data via |
|
|
1695 | AnyEvent::Handle. It is also written in pure-perl, but can take |
|
|
1696 | advantage of the ultra-high-speed JSON::XS module when it is |
|
|
1697 | installed. |
|
|
1698 | |
|
|
1699 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1700 | installed. |
|
|
1701 | |
|
|
1702 | Net::SSLeay |
|
|
1703 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
|
|
1704 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
|
|
1705 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
|
|
1706 | |
|
|
1707 | Time::HiRes |
|
|
1708 | This module is part of perl since release 5.008. It will be used |
|
|
1709 | when the chosen event library does not come with a timing source on |
|
|
1710 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
|
|
1711 | additionally use it to try to use a monotonic clock for timing |
|
|
1712 | stability. |
|
|
1713 | |
1608 | FORK |
1714 | FORK |
1609 | Most event libraries are not fork-safe. The ones who are usually are |
1715 | Most event libraries are not fork-safe. The ones who are usually are |
1610 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1716 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1611 | Only EV is fully fork-aware. |
1717 | Only EV is fully fork-aware. |
1612 | |
1718 | |
1613 | If you have to fork, you must either do so *before* creating your first |
1719 | If you have to fork, you must either do so *before* creating your first |
1614 | watcher OR you must not use AnyEvent at all in the child. |
1720 | watcher OR you must not use AnyEvent at all in the child OR you must do |
|
|
1721 | something completely out of the scope of AnyEvent. |
1615 | |
1722 | |
1616 | SECURITY CONSIDERATIONS |
1723 | SECURITY CONSIDERATIONS |
1617 | AnyEvent can be forced to load any event model via |
1724 | AnyEvent can be forced to load any event model via |
1618 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1725 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1619 | to execute arbitrary code or directly gain access, it can easily be used |
1726 | to execute arbitrary code or directly gain access, it can easily be used |