… | |
… | |
5 | Qt and POE are various supported event loops/environments. |
5 | Qt and POE are various supported event loops/environments. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
|
|
10 | # if you prefer function calls, look at the L<AE> manpage for |
|
|
11 | # an alternative API. |
|
|
12 | |
10 | # file descriptor readable |
13 | # file handle or descriptor readable |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
14 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
12 | |
15 | |
13 | # one-shot or repeating timers |
16 | # one-shot or repeating timers |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
17 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
18 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
… | |
… | |
486 | $done->recv; |
489 | $done->recv; |
487 | |
490 | |
488 | IDLE WATCHERS |
491 | IDLE WATCHERS |
489 | $w = AnyEvent->idle (cb => <callback>); |
492 | $w = AnyEvent->idle (cb => <callback>); |
490 | |
493 | |
491 | Sometimes there is a need to do something, but it is not so important to |
494 | Repeatedly invoke the callback after the process becomes idle, until |
492 | do it instantly, but only when there is nothing better to do. This |
495 | either the watcher is destroyed or new events have been detected. |
493 | "nothing better to do" is usually defined to be "no other events need |
|
|
494 | attention by the event loop". |
|
|
495 | |
496 | |
496 | Idle watchers ideally get invoked when the event loop has nothing better |
497 | Idle watchers are useful when there is a need to do something, but it is |
497 | to do, just before it would block the process to wait for new events. |
498 | not so important (or wise) to do it instantly. The callback will be |
498 | Instead of blocking, the idle watcher is invoked. |
499 | invoked only when there is "nothing better to do", which is usually |
|
|
500 | defined as "all outstanding events have been handled and no new events |
|
|
501 | have been detected". That means that idle watchers ideally get invoked |
|
|
502 | when the event loop has just polled for new events but none have been |
|
|
503 | detected. Instead of blocking to wait for more events, the idle watchers |
|
|
504 | will be invoked. |
499 | |
505 | |
500 | Most event loops unfortunately do not really support idle watchers (only |
506 | Unfortunately, most event loops do not really support idle watchers |
501 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
507 | (only EV, Event and Glib do it in a usable fashion) - for the rest, |
502 | will simply call the callback "from time to time". |
508 | AnyEvent will simply call the callback "from time to time". |
503 | |
509 | |
504 | Example: read lines from STDIN, but only process them when the program |
510 | Example: read lines from STDIN, but only process them when the program |
505 | is otherwise idle: |
511 | is otherwise idle: |
506 | |
512 | |
507 | my @lines; # read data |
513 | my @lines; # read data |
… | |
… | |
586 | which eventually calls "-> send", and the "consumer side", which waits |
592 | which eventually calls "-> send", and the "consumer side", which waits |
587 | for the send to occur. |
593 | for the send to occur. |
588 | |
594 | |
589 | Example: wait for a timer. |
595 | Example: wait for a timer. |
590 | |
596 | |
591 | # wait till the result is ready |
597 | # condition: "wait till the timer is fired" |
592 | my $result_ready = AnyEvent->condvar; |
598 | my $timer_fired = AnyEvent->condvar; |
593 | |
599 | |
594 | # do something such as adding a timer |
600 | # create the timer - we could wait for, say |
595 | # or socket watcher the calls $result_ready->send |
601 | # a handle becomign ready, or even an |
596 | # when the "result" is ready. |
602 | # AnyEvent::HTTP request to finish, but |
597 | # in this case, we simply use a timer: |
603 | # in this case, we simply use a timer: |
598 | my $w = AnyEvent->timer ( |
604 | my $w = AnyEvent->timer ( |
599 | after => 1, |
605 | after => 1, |
600 | cb => sub { $result_ready->send }, |
606 | cb => sub { $timer_fired->send }, |
601 | ); |
607 | ); |
602 | |
608 | |
603 | # this "blocks" (while handling events) till the callback |
609 | # this "blocks" (while handling events) till the callback |
604 | # calls ->send |
610 | # calls ->send |
605 | $result_ready->recv; |
611 | $timer_fired->recv; |
606 | |
612 | |
607 | Example: wait for a timer, but take advantage of the fact that condition |
613 | Example: wait for a timer, but take advantage of the fact that condition |
608 | variables are also callable directly. |
614 | variables are also callable directly. |
609 | |
615 | |
610 | my $done = AnyEvent->condvar; |
616 | my $done = AnyEvent->condvar; |
… | |
… | |
1073 | Has special support for AnyEvent via Coro::AnyEvent. |
1079 | Has special support for AnyEvent via Coro::AnyEvent. |
1074 | |
1080 | |
1075 | SIMPLIFIED AE API |
1081 | SIMPLIFIED AE API |
1076 | Starting with version 5.0, AnyEvent officially supports a second, much |
1082 | Starting with version 5.0, AnyEvent officially supports a second, much |
1077 | simpler, API that is designed to reduce the calling, typing and memory |
1083 | simpler, API that is designed to reduce the calling, typing and memory |
1078 | overhead. |
1084 | overhead by using function call syntax and a fixed number of parameters. |
1079 | |
1085 | |
1080 | See the AE manpage for details. |
1086 | See the AE manpage for details. |
1081 | |
1087 | |
1082 | ERROR AND EXCEPTION HANDLING |
1088 | ERROR AND EXCEPTION HANDLING |
1083 | In general, AnyEvent does not do any error handling - it relies on the |
1089 | In general, AnyEvent does not do any error handling - it relies on the |
… | |
… | |
1348 | |
1354 | |
1349 | The actual code goes further and collects all errors ("die"s, |
1355 | The actual code goes further and collects all errors ("die"s, |
1350 | exceptions) that occurred during request processing. The "result" method |
1356 | exceptions) that occurred during request processing. The "result" method |
1351 | detects whether an exception as thrown (it is stored inside the $txn |
1357 | detects whether an exception as thrown (it is stored inside the $txn |
1352 | object) and just throws the exception, which means connection errors and |
1358 | object) and just throws the exception, which means connection errors and |
1353 | other problems get reported tot he code that tries to use the result, |
1359 | other problems get reported to the code that tries to use the result, |
1354 | not in a random callback. |
1360 | not in a random callback. |
1355 | |
1361 | |
1356 | All of this enables the following usage styles: |
1362 | All of this enables the following usage styles: |
1357 | |
1363 | |
1358 | 1. Blocking: |
1364 | 1. Blocking: |
… | |
… | |
1771 | clock is available, can take avdantage of advanced kernel interfaces |
1777 | clock is available, can take avdantage of advanced kernel interfaces |
1772 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
1778 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
1773 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
1779 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
1774 | Glib::EV). |
1780 | Glib::EV). |
1775 | |
1781 | |
|
|
1782 | If you only use backends that rely on another event loop (e.g. |
|
|
1783 | "Tk"), then this module will do nothing for you. |
|
|
1784 | |
1776 | Guard |
1785 | Guard |
1777 | The guard module, when used, will be used to implement |
1786 | The guard module, when used, will be used to implement |
1778 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
1787 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
1779 | uses a lot less memory), but otherwise doesn't affect guard |
1788 | uses a lot less memory), but otherwise doesn't affect guard |
1780 | operation much. It is purely used for performance. |
1789 | operation much. It is purely used for performance. |
1781 | |
1790 | |
1782 | JSON and JSON::XS |
1791 | JSON and JSON::XS |
1783 | One of these modules is required when you want to read or write JSON |
1792 | One of these modules is required when you want to read or write JSON |
1784 | data via AnyEvent::Handle. It is also written in pure-perl, but can |
1793 | data via AnyEvent::Handle. JSON is also written in pure-perl, but |
1785 | take advantage of the ultra-high-speed JSON::XS module when it is |
1794 | can take advantage of the ultra-high-speed JSON::XS module when it |
1786 | installed. |
1795 | is installed. |
1787 | |
|
|
1788 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1789 | installed. |
|
|
1790 | |
1796 | |
1791 | Net::SSLeay |
1797 | Net::SSLeay |
1792 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
1798 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
1793 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
1799 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
1794 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
1800 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
… | |
… | |
1800 | additionally use it to try to use a monotonic clock for timing |
1806 | additionally use it to try to use a monotonic clock for timing |
1801 | stability. |
1807 | stability. |
1802 | |
1808 | |
1803 | FORK |
1809 | FORK |
1804 | Most event libraries are not fork-safe. The ones who are usually are |
1810 | Most event libraries are not fork-safe. The ones who are usually are |
1805 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1811 | because they rely on inefficient but fork-safe "select" or "poll" calls |
1806 | Only EV is fully fork-aware. |
1812 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
|
|
1813 | epoll are usually badly thought-out hacks that are incompatible with |
|
|
1814 | fork in one way or another. Only EV is fully fork-aware and ensures that |
|
|
1815 | you continue event-processing in both parent and child (or both, if you |
|
|
1816 | know what you are doing). |
1807 | |
1817 | |
1808 | This means that, in general, you cannot fork and do event processing in |
1818 | This means that, in general, you cannot fork and do event processing in |
1809 | the child if a watcher was created before the fork (which in turn |
1819 | the child if the event library was initialised before the fork (which |
1810 | initialises the event library). |
1820 | usually happens when the first AnyEvent watcher is created, or the |
|
|
1821 | library is loaded). |
1811 | |
1822 | |
1812 | If you have to fork, you must either do so *before* creating your first |
1823 | If you have to fork, you must either do so *before* creating your first |
1813 | watcher OR you must not use AnyEvent at all in the child OR you must do |
1824 | watcher OR you must not use AnyEvent at all in the child OR you must do |
1814 | something completely out of the scope of AnyEvent. |
1825 | something completely out of the scope of AnyEvent. |
1815 | |
1826 | |
1816 | The problem of doing event processing in the parent *and* the child is |
1827 | The problem of doing event processing in the parent *and* the child is |
1817 | much more complicated: even for backends that *are* fork-aware or |
1828 | much more complicated: even for backends that *are* fork-aware or |
1818 | fork-safe, their behaviour is not usually what you want: fork clones all |
1829 | fork-safe, their behaviour is not usually what you want: fork clones all |
1819 | watchers, that means all timers, I/O watchers etc. are active in both |
1830 | watchers, that means all timers, I/O watchers etc. are active in both |
1820 | parent and child, which is almost never what you want. |
1831 | parent and child, which is almost never what you want. USing "exec" to |
|
|
1832 | start worker children from some kind of manage rprocess is usually |
|
|
1833 | preferred, because it is much easier and cleaner, at the expense of |
|
|
1834 | having to have another binary. |
1821 | |
1835 | |
1822 | SECURITY CONSIDERATIONS |
1836 | SECURITY CONSIDERATIONS |
1823 | AnyEvent can be forced to load any event model via |
1837 | AnyEvent can be forced to load any event model via |
1824 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1838 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1825 | to execute arbitrary code or directly gain access, it can easily be used |
1839 | to execute arbitrary code or directly gain access, it can easily be used |