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Revision 1.64 by root, Fri Dec 31 04:50:44 2010 UTC vs.
Revision 1.71 by root, Wed Aug 21 08:40:28 2013 UTC

1NAME 1NAME
2 AnyEvent - the DBI of event loop programming 2 AnyEvent - the DBI of event loop programming
3 3
4 EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, 4 EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async,
5 Qt and POE are various supported event loops/environments. 5 Qt, FLTK and POE are various supported event loops/environments.
6 6
7SYNOPSIS 7SYNOPSIS
8 use AnyEvent; 8 use AnyEvent;
9 9
10 # if you prefer function calls, look at the AE manpage for 10 # if you prefer function calls, look at the AE manpage for
… …
115 The interface itself is vaguely similar, but not identical to the Event 115 The interface itself is vaguely similar, but not identical to the Event
116 module. 116 module.
117 117
118 During the first call of any watcher-creation method, the module tries 118 During the first call of any watcher-creation method, the module tries
119 to detect the currently loaded event loop by probing whether one of the 119 to detect the currently loaded event loop by probing whether one of the
120 following modules is already loaded: EV, AnyEvent::Impl::Perl, Event, 120 following modules is already loaded: EV, AnyEvent::Loop, Event, Glib,
121 Glib, Tk, Event::Lib, Qt, POE. The first one found is used. If none are 121 Tk, Event::Lib, Qt, POE. The first one found is used. If none are
122 detected, the module tries to load the first four modules in the order 122 detected, the module tries to load the first four modules in the order
123 given; but note that if EV is not available, the pure-perl 123 given; but note that if EV is not available, the pure-perl
124 AnyEvent::Impl::Perl should always work, so the other two are not 124 AnyEvent::Loop should always work, so the other two are not normally
125 normally tried. 125 tried.
126 126
127 Because AnyEvent first checks for modules that are already loaded, 127 Because AnyEvent first checks for modules that are already loaded,
128 loading an event model explicitly before first using AnyEvent will 128 loading an event model explicitly before first using AnyEvent will
129 likely make that model the default. For example: 129 likely make that model the default. For example:
130 130
… …
136 The *likely* means that, if any module loads another event model and 136 The *likely* means that, if any module loads another event model and
137 starts using it, all bets are off - this case should be very rare 137 starts using it, all bets are off - this case should be very rare
138 though, as very few modules hardcode event loops without announcing this 138 though, as very few modules hardcode event loops without announcing this
139 very loudly. 139 very loudly.
140 140
141 The pure-perl implementation of AnyEvent is called 141 The pure-perl implementation of AnyEvent is called "AnyEvent::Loop".
142 "AnyEvent::Impl::Perl". Like other event modules you can load it 142 Like other event modules you can load it explicitly and enjoy the high
143 explicitly and enjoy the high availability of that event loop :) 143 availability of that event loop :)
144 144
145WATCHERS 145WATCHERS
146 AnyEvent has the central concept of a *watcher*, which is an object that 146 AnyEvent has the central concept of a *watcher*, which is an object that
147 stores relevant data for each kind of event you are waiting for, such as 147 stores relevant data for each kind of event you are waiting for, such as
148 the callback to call, the file handle to watch, etc. 148 the callback to call, the file handle to watch, etc.
… …
262 262
263 Example 2: fire an event after 0.5 seconds, then roughly every second. 263 Example 2: fire an event after 0.5 seconds, then roughly every second.
264 264
265 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { 265 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
266 warn "timeout\n"; 266 warn "timeout\n";
267 }; 267 });
268 268
269 TIMING ISSUES 269 TIMING ISSUES
270 There are two ways to handle timers: based on real time (relative, "fire 270 There are two ways to handle timers: based on real time (relative, "fire
271 in 10 seconds") and based on wallclock time (absolute, "fire at 12 271 in 10 seconds") and based on wallclock time (absolute, "fire at 12
272 o'clock"). 272 o'clock").
… …
347 can get whatever behaviour you want with any event loop, by taking 347 can get whatever behaviour you want with any event loop, by taking
348 the difference between "AnyEvent->time" and "AnyEvent->now" into 348 the difference between "AnyEvent->time" and "AnyEvent->now" into
349 account. 349 account.
350 350
351 AnyEvent->now_update 351 AnyEvent->now_update
352 Some event loops (such as EV or AnyEvent::Impl::Perl) cache the 352 Some event loops (such as EV or AnyEvent::Loop) cache the current
353 current time for each loop iteration (see the discussion of 353 time for each loop iteration (see the discussion of AnyEvent->now,
354 AnyEvent->now, above). 354 above).
355 355
356 When a callback runs for a long time (or when the process sleeps), 356 When a callback runs for a long time (or when the process sleeps),
357 then this "current" time will differ substantially from the real 357 then this "current" time will differ substantially from the real
358 time, which might affect timers and time-outs. 358 time, which might affect timers and time-outs.
359 359
… …
403 will not restart syscalls (that includes Async::Interrupt and AnyEvent's 403 will not restart syscalls (that includes Async::Interrupt and AnyEvent's
404 pure perl implementation). 404 pure perl implementation).
405 405
406 Safe/Unsafe Signals 406 Safe/Unsafe Signals
407 Perl signals can be either "safe" (synchronous to opcode handling) or 407 Perl signals can be either "safe" (synchronous to opcode handling) or
408 "unsafe" (asynchronous) - the former might get delayed indefinitely, the 408 "unsafe" (asynchronous) - the former might delay signal delivery
409 latter might corrupt your memory. 409 indefinitely, the latter might corrupt your memory.
410 410
411 AnyEvent signal handlers are, in addition, synchronous to the event 411 AnyEvent signal handlers are, in addition, synchronous to the event
412 loop, i.e. they will not interrupt your running perl program but will 412 loop, i.e. they will not interrupt your running perl program but will
413 only be called as part of the normal event handling (just like timer, 413 only be called as part of the normal event handling (just like timer,
414 I/O etc. callbacks, too). 414 I/O etc. callbacks, too).
… …
416 Signal Races, Delays and Workarounds 416 Signal Races, Delays and Workarounds
417 Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching 417 Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
418 callbacks to signals in a generic way, which is a pity, as you cannot do 418 callbacks to signals in a generic way, which is a pity, as you cannot do
419 race-free signal handling in perl, requiring C libraries for this. 419 race-free signal handling in perl, requiring C libraries for this.
420 AnyEvent will try to do its best, which means in some cases, signals 420 AnyEvent will try to do its best, which means in some cases, signals
421 will be delayed. The maximum time a signal might be delayed is specified 421 will be delayed. The maximum time a signal might be delayed is 10
422 in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable 422 seconds by default, but can be overriden via
423 can be changed only before the first signal watcher is created, and 423 $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} or $AnyEvent::MAX_SIGNAL_LATENCY
424 should be left alone otherwise. This variable determines how often 424 - see the "ENVIRONMENT VARIABLES" section for details.
425 AnyEvent polls for signals (in case a wake-up was missed). Higher values
426 will cause fewer spurious wake-ups, which is better for power and CPU
427 saving.
428 425
429 All these problems can be avoided by installing the optional 426 All these problems can be avoided by installing the optional
430 Async::Interrupt module, which works with most event loops. It will not 427 Async::Interrupt module, which works with most event loops. It will not
431 work with inherently broken event loops such as Event or Event::Lib (and 428 work with inherently broken event loops such as Event or Event::Lib (and
432 not with POE currently, as POE does its own workaround with one-second
433 latency). For those, you just have to suffer the delays. 429 not with POE currently). For those, you just have to suffer the delays.
434 430
435 CHILD PROCESS WATCHERS 431 CHILD PROCESS WATCHERS
436 $w = AnyEvent->child (pid => <process id>, cb => <callback>); 432 $w = AnyEvent->child (pid => <process id>, cb => <callback>);
437 433
438 You can also watch for a child process exit and catch its exit status. 434 You can also watch for a child process exit and catch its exit status.
… …
466 This means you cannot create a child watcher as the very first thing in 462 This means you cannot create a child watcher as the very first thing in
467 an AnyEvent program, you *have* to create at least one watcher before 463 an AnyEvent program, you *have* to create at least one watcher before
468 you "fork" the child (alternatively, you can call "AnyEvent::detect"). 464 you "fork" the child (alternatively, you can call "AnyEvent::detect").
469 465
470 As most event loops do not support waiting for child events, they will 466 As most event loops do not support waiting for child events, they will
471 be emulated by AnyEvent in most cases, in which the latency and race 467 be emulated by AnyEvent in most cases, in which case the latency and
472 problems mentioned in the description of signal watchers apply. 468 race problems mentioned in the description of signal watchers apply.
473 469
474 Example: fork a process and wait for it 470 Example: fork a process and wait for it
475 471
476 my $done = AnyEvent->condvar; 472 my $done = AnyEvent->condvar;
477 473
… …
740 }; 736 };
741 } 737 }
742 738
743 $cv->end; 739 $cv->end;
744 740
741 ...
742
743 my $results = $cv->recv;
744
745 This code fragment supposedly pings a number of hosts and calls 745 This code fragment supposedly pings a number of hosts and calls
746 "send" after results for all then have have been gathered - in any 746 "send" after results for all then have have been gathered - in any
747 order. To achieve this, the code issues a call to "begin" when it 747 order. To achieve this, the code issues a call to "begin" when it
748 starts each ping request and calls "end" when it has received some 748 starts each ping request and calls "end" when it has received some
749 result for it. Since "begin" and "end" only maintain a counter, the 749 result for it. Since "begin" and "end" only maintain a counter, the
… …
778 In list context, all parameters passed to "send" will be returned, 778 In list context, all parameters passed to "send" will be returned,
779 in scalar context only the first one will be returned. 779 in scalar context only the first one will be returned.
780 780
781 Note that doing a blocking wait in a callback is not supported by 781 Note that doing a blocking wait in a callback is not supported by
782 any event loop, that is, recursive invocation of a blocking "->recv" 782 any event loop, that is, recursive invocation of a blocking "->recv"
783 is not allowed, and the "recv" call will "croak" if such a condition 783 is not allowed and the "recv" call will "croak" if such a condition
784 is detected. This condition can be slightly loosened by using 784 is detected. This requirement can be dropped by relying on
785 Coro::AnyEvent, which allows you to do a blocking "->recv" from any 785 Coro::AnyEvent , which allows you to do a blocking "->recv" from any
786 thread that doesn't run the event loop itself. 786 thread that doesn't run the event loop itself. Coro::AnyEvent is
787 loaded automatically when Coro is used with AnyEvent, so code does
788 not need to do anything special to take advantage of that: any code
789 that would normally block your program because it calls "recv", be
790 executed in an "async" thread instead without blocking other
791 threads.
787 792
788 Not all event models support a blocking wait - some die in that case 793 Not all event models support a blocking wait - some die in that case
789 (programs might want to do that to stay interactive), so *if you are 794 (programs might want to do that to stay interactive), so *if you are
790 using this from a module, never require a blocking wait*. Instead, 795 using this from a module, never require a blocking wait*. Instead,
791 let the caller decide whether the call will block or not (for 796 let the caller decide whether the call will block or not (for
… …
821 use. If EV is not installed, then AnyEvent will fall back to its own 826 use. If EV is not installed, then AnyEvent will fall back to its own
822 pure-perl implementation, which is available everywhere as it comes 827 pure-perl implementation, which is available everywhere as it comes
823 with AnyEvent itself. 828 with AnyEvent itself.
824 829
825 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 830 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
826 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 831 AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
827 832
828 Backends that are transparently being picked up when they are used. 833 Backends that are transparently being picked up when they are used.
829 These will be used if they are already loaded when the first watcher 834 These will be used if they are already loaded when the first watcher
830 is created, in which case it is assumed that the application is 835 is created, in which case it is assumed that the application is
831 using them. This means that AnyEvent will automatically pick the 836 using them. This means that AnyEvent will automatically pick the
… …
839 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 844 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
840 AnyEvent::Impl::POE based on POE, very slow, some limitations. 845 AnyEvent::Impl::POE based on POE, very slow, some limitations.
841 AnyEvent::Impl::Irssi used when running within irssi. 846 AnyEvent::Impl::Irssi used when running within irssi.
842 AnyEvent::Impl::IOAsync based on IO::Async. 847 AnyEvent::Impl::IOAsync based on IO::Async.
843 AnyEvent::Impl::Cocoa based on Cocoa::EventLoop. 848 AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
849 AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
844 850
845 Backends with special needs. 851 Backends with special needs.
846 Qt requires the Qt::Application to be instantiated first, but will 852 Qt requires the Qt::Application to be instantiated first, but will
847 otherwise be picked up automatically. As long as the main program 853 otherwise be picked up automatically. As long as the main program
848 instantiates the application before any AnyEvent watchers are 854 instantiates the application before any AnyEvent watchers are
… …
885 Returns $AnyEvent::MODEL, forcing autodetection of the event model 891 Returns $AnyEvent::MODEL, forcing autodetection of the event model
886 if necessary. You should only call this function right before you 892 if necessary. You should only call this function right before you
887 would have created an AnyEvent watcher anyway, that is, as late as 893 would have created an AnyEvent watcher anyway, that is, as late as
888 possible at runtime, and not e.g. during initialisation of your 894 possible at runtime, and not e.g. during initialisation of your
889 module. 895 module.
896
897 The effect of calling this function is as if a watcher had been
898 created (specifically, actions that happen "when the first watcher
899 is created" happen when calling detetc as well).
890 900
891 If you need to do some initialisation before AnyEvent watchers are 901 If you need to do some initialisation before AnyEvent watchers are
892 created, use "post_detect". 902 created, use "post_detect".
893 903
894 $guard = AnyEvent::post_detect { BLOCK } 904 $guard = AnyEvent::post_detect { BLOCK }
… …
956 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent 966 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
957 # as soon as it is 967 # as soon as it is
958 push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; 968 push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
959 } 969 }
960 970
971 AnyEvent::postpone { BLOCK }
972 Arranges for the block to be executed as soon as possible, but not
973 before the call itself returns. In practise, the block will be
974 executed just before the event loop polls for new events, or shortly
975 afterwards.
976
977 This function never returns anything (to make the "return postpone {
978 ... }" idiom more useful.
979
980 To understand the usefulness of this function, consider a function
981 that asynchronously does something for you and returns some
982 transaction object or guard to let you cancel the operation. For
983 example, "AnyEvent::Socket::tcp_connect":
984
985 # start a conenction attempt unless one is active
986 $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
987 delete $self->{connect_guard};
988 ...
989 };
990
991 Imagine that this function could instantly call the callback, for
992 example, because it detects an obvious error such as a negative port
993 number. Invoking the callback before the function returns causes
994 problems however: the callback will be called and will try to delete
995 the guard object. But since the function hasn't returned yet, there
996 is nothing to delete. When the function eventually returns it will
997 assign the guard object to "$self->{connect_guard}", where it will
998 likely never be deleted, so the program thinks it is still trying to
999 connect.
1000
1001 This is where "AnyEvent::postpone" should be used. Instead of
1002 calling the callback directly on error:
1003
1004 $cb->(undef), return # signal error to callback, BAD!
1005 if $some_error_condition;
1006
1007 It should use "postpone":
1008
1009 AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
1010 if $some_error_condition;
1011
1012 AnyEvent::log $level, $msg[, @args]
1013 Log the given $msg at the given $level.
1014
1015 If AnyEvent::Log is not loaded then this function makes a simple
1016 test to see whether the message will be logged. If the test succeeds
1017 it will load AnyEvent::Log and call "AnyEvent::Log::log" -
1018 consequently, look at the AnyEvent::Log documentation for details.
1019
1020 If the test fails it will simply return. Right now this happens when
1021 a numerical loglevel is used and it is larger than the level
1022 specified via $ENV{PERL_ANYEVENT_VERBOSE}.
1023
1024 If you want to sprinkle loads of logging calls around your code,
1025 consider creating a logger callback with the "AnyEvent::Log::logger"
1026 function, which can reduce typing, codesize and can reduce the
1027 logging overhead enourmously.
1028
961WHAT TO DO IN A MODULE 1029WHAT TO DO IN A MODULE
962 As a module author, you should "use AnyEvent" and call AnyEvent methods 1030 As a module author, you should "use AnyEvent" and call AnyEvent methods
963 freely, but you should not load a specific event module or rely on it. 1031 freely, but you should not load a specific event module or rely on it.
964 1032
965 Be careful when you create watchers in the module body - AnyEvent will 1033 Be careful when you create watchers in the module body - AnyEvent will
… …
995 will decide on the event model to use as soon as it creates watchers, 1063 will decide on the event model to use as soon as it creates watchers,
996 and it might choose the wrong one unless you load the correct one 1064 and it might choose the wrong one unless you load the correct one
997 yourself. 1065 yourself.
998 1066
999 You can chose to use a pure-perl implementation by loading the 1067 You can chose to use a pure-perl implementation by loading the
1000 "AnyEvent::Impl::Perl" module, which gives you similar behaviour 1068 "AnyEvent::Loop" module, which gives you similar behaviour everywhere,
1001 everywhere, but letting AnyEvent chose the model is generally better. 1069 but letting AnyEvent chose the model is generally better.
1002 1070
1003 MAINLOOP EMULATION 1071 MAINLOOP EMULATION
1004 Sometimes (often for short test scripts, or even standalone programs who 1072 Sometimes (often for short test scripts, or even standalone programs who
1005 only want to use AnyEvent), you do not want to run a specific event 1073 only want to use AnyEvent), you do not want to run a specific event
1006 loop. 1074 loop.
… …
1018 1086
1019OTHER MODULES 1087OTHER MODULES
1020 The following is a non-exhaustive list of additional modules that use 1088 The following is a non-exhaustive list of additional modules that use
1021 AnyEvent as a client and can therefore be mixed easily with other 1089 AnyEvent as a client and can therefore be mixed easily with other
1022 AnyEvent modules and other event loops in the same program. Some of the 1090 AnyEvent modules and other event loops in the same program. Some of the
1023 modules come as part of AnyEvent, the others are available via CPAN. 1091 modules come as part of AnyEvent, the others are available via CPAN (see
1092 <http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for a longer
1093 non-exhaustive list), and the list is heavily biased towards modules of
1094 the AnyEvent author himself :)
1024 1095
1025 AnyEvent::Util 1096 AnyEvent::Util (part of the AnyEvent distribution)
1026 Contains various utility functions that replace often-used blocking 1097 Contains various utility functions that replace often-used blocking
1027 functions such as "inet_aton" with event/callback-based versions. 1098 functions such as "inet_aton" with event/callback-based versions.
1028 1099
1029 AnyEvent::Socket 1100 AnyEvent::Socket (part of the AnyEvent distribution)
1030 Provides various utility functions for (internet protocol) sockets, 1101 Provides various utility functions for (internet protocol) sockets,
1031 addresses and name resolution. Also functions to create non-blocking 1102 addresses and name resolution. Also functions to create non-blocking
1032 tcp connections or tcp servers, with IPv6 and SRV record support and 1103 tcp connections or tcp servers, with IPv6 and SRV record support and
1033 more. 1104 more.
1034 1105
1035 AnyEvent::Handle 1106 AnyEvent::Handle (part of the AnyEvent distribution)
1036 Provide read and write buffers, manages watchers for reads and 1107 Provide read and write buffers, manages watchers for reads and
1037 writes, supports raw and formatted I/O, I/O queued and fully 1108 writes, supports raw and formatted I/O, I/O queued and fully
1038 transparent and non-blocking SSL/TLS (via AnyEvent::TLS). 1109 transparent and non-blocking SSL/TLS (via AnyEvent::TLS).
1039 1110
1040 AnyEvent::DNS 1111 AnyEvent::DNS (part of the AnyEvent distribution)
1041 Provides rich asynchronous DNS resolver capabilities. 1112 Provides rich asynchronous DNS resolver capabilities.
1042 1113
1043 AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, 1114 AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD,
1044 AnyEvent::IGS, AnyEvent::FCP 1115 AnyEvent::IGS, AnyEvent::FCP
1045 Implement event-based interfaces to the protocols of the same name 1116 Implement event-based interfaces to the protocols of the same name
1046 (for the curious, IGS is the International Go Server and FCP is the 1117 (for the curious, IGS is the International Go Server and FCP is the
1047 Freenet Client Protocol). 1118 Freenet Client Protocol).
1048 1119
1049 AnyEvent::Handle::UDP 1120 AnyEvent::AIO (part of the AnyEvent distribution)
1050 Here be danger!
1051
1052 As Pauli would put it, "Not only is it not right, it's not even
1053 wrong!" - there are so many things wrong with AnyEvent::Handle::UDP,
1054 most notably its use of a stream-based API with a protocol that
1055 isn't streamable, that the only way to improve it is to delete it.
1056
1057 It features data corruption (but typically only under load) and
1058 general confusion. On top, the author is not only clueless about UDP
1059 but also fact-resistant - some gems of his understanding: "connect
1060 doesn't work with UDP", "UDP packets are not IP packets", "UDP only
1061 has datagrams, not packets", "I don't need to implement proper error
1062 checking as UDP doesn't support error checking" and so on - he
1063 doesn't even understand what's wrong with his module when it is
1064 explained to him.
1065
1066 AnyEvent::DBI
1067 Executes DBI requests asynchronously in a proxy process for you,
1068 notifying you in an event-based way when the operation is finished.
1069
1070 AnyEvent::AIO
1071 Truly asynchronous (as opposed to non-blocking) I/O, should be in 1121 Truly asynchronous (as opposed to non-blocking) I/O, should be in
1072 the toolbox of every event programmer. AnyEvent::AIO transparently 1122 the toolbox of every event programmer. AnyEvent::AIO transparently
1073 fuses IO::AIO and AnyEvent together, giving AnyEvent access to 1123 fuses IO::AIO and AnyEvent together, giving AnyEvent access to
1074 event-based file I/O, and much more. 1124 event-based file I/O, and much more.
1075 1125
1126 AnyEvent::Filesys::Notify
1127 AnyEvent is good for non-blocking stuff, but it can't detect file or
1128 path changes (e.g. "watch this directory for new files", "watch this
1129 file for changes"). The AnyEvent::Filesys::Notify module promises to
1130 do just that in a portbale fashion, supporting inotify on GNU/Linux
1131 and some weird, without doubt broken, stuff on OS X to monitor
1132 files. It can fall back to blocking scans at regular intervals
1133 transparently on other platforms, so it's about as portable as it
1134 gets.
1135
1136 (I haven't used it myself, but I haven't heard anybody complaining
1137 about it yet).
1138
1139 AnyEvent::DBI
1140 Executes DBI requests asynchronously in a proxy process for you,
1141 notifying you in an event-based way when the operation is finished.
1142
1076 AnyEvent::HTTPD 1143 AnyEvent::HTTPD
1077 A simple embedded webserver. 1144 A simple embedded webserver.
1078 1145
1079 AnyEvent::FastPing 1146 AnyEvent::FastPing
1080 The fastest ping in the west. 1147 The fastest ping in the west.
1081 1148
1082 Coro 1149 Coro
1083 Has special support for AnyEvent via Coro::AnyEvent. 1150 Has special support for AnyEvent via Coro::AnyEvent, which allows
1151 you to simply invert the flow control - don't call us, we will call
1152 you:
1153
1154 async {
1155 Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
1156 print "5 seconds later!\n";
1157
1158 Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
1159 my $line = <STDIN>; # works for ttys
1160
1161 AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
1162 my ($body, $hdr) = Coro::rouse_wait;
1163 };
1084 1164
1085SIMPLIFIED AE API 1165SIMPLIFIED AE API
1086 Starting with version 5.0, AnyEvent officially supports a second, much 1166 Starting with version 5.0, AnyEvent officially supports a second, much
1087 simpler, API that is designed to reduce the calling, typing and memory 1167 simpler, API that is designed to reduce the calling, typing and memory
1088 overhead by using function call syntax and a fixed number of parameters. 1168 overhead by using function call syntax and a fixed number of parameters.
… …
1104 The pure perl event loop simply re-throws the exception (usually within 1184 The pure perl event loop simply re-throws the exception (usually within
1105 "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", 1185 "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
1106 Glib uses "install_exception_handler" and so on. 1186 Glib uses "install_exception_handler" and so on.
1107 1187
1108ENVIRONMENT VARIABLES 1188ENVIRONMENT VARIABLES
1109 The following environment variables are used by this module or its 1189 AnyEvent supports a number of environment variables that tune the
1110 submodules. 1190 runtime behaviour. They are usually evaluated when AnyEvent is loaded,
1191 initialised, or a submodule that uses them is loaded. Many of them also
1192 cause AnyEvent to load additional modules - for example,
1193 "PERL_ANYEVENT_DEBUG_WRAP" causes the AnyEvent::Debug module to be
1194 loaded.
1111 1195
1112 Note that AnyEvent will remove *all* environment variables starting with 1196 All the environment variables documented here start with
1113 "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is 1197 "PERL_ANYEVENT_", which is what AnyEvent considers its own namespace.
1114 enabled. 1198 Other modules are encouraged (but by no means required) to use
1199 "PERL_ANYEVENT_SUBMODULE" if they have registered the
1200 AnyEvent::Submodule namespace on CPAN, for any submodule. For example,
1201 AnyEvent::HTTP could be expected to use "PERL_ANYEVENT_HTTP_PROXY" (it
1202 should not access env variables starting with "AE_", see below).
1203
1204 All variables can also be set via the "AE_" prefix, that is, instead of
1205 setting "PERL_ANYEVENT_VERBOSE" you can also set "AE_VERBOSE". In case
1206 there is a clash btween anyevent and another program that uses
1207 "AE_something" you can set the corresponding "PERL_ANYEVENT_something"
1208 variable to the empty string, as those variables take precedence.
1209
1210 When AnyEvent is first loaded, it copies all "AE_xxx" env variables to
1211 their "PERL_ANYEVENT_xxx" counterpart unless that variable already
1212 exists. If taint mode is on, then AnyEvent will remove *all* environment
1213 variables starting with "PERL_ANYEVENT_" from %ENV (or replace them with
1214 "undef" or the empty string, if the corresaponding "AE_" variable is
1215 set).
1216
1217 The exact algorithm is currently:
1218
1219 1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
1220 2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
1221 3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
1222
1223 This ensures that child processes will not see the "AE_" variables.
1224
1225 The following environment variables are currently known to AnyEvent:
1115 1226
1116 "PERL_ANYEVENT_VERBOSE" 1227 "PERL_ANYEVENT_VERBOSE"
1117 By default, AnyEvent will be completely silent except in fatal 1228 By default, AnyEvent will log messages with loglevel 4 ("error") or
1118 conditions. You can set this environment variable to make AnyEvent 1229 higher (see AnyEvent::Log). You can set this environment variable to
1119 more talkative. 1230 a numerical loglevel to make AnyEvent more (or less) talkative.
1120 1231
1232 If you want to do more than just set the global logging level you
1233 should have a look at "PERL_ANYEVENT_LOG", which allows much more
1234 complex specifications.
1235
1236 When set to 0 ("off"), then no messages whatsoever will be logged
1237 with everything else at defaults.
1238
1121 When set to 1 or higher, causes AnyEvent to warn about unexpected 1239 When set to 5 or higher ("warn"), AnyEvent warns about unexpected
1122 conditions, such as not being able to load the event model specified 1240 conditions, such as not being able to load the event model specified
1123 by "PERL_ANYEVENT_MODEL". 1241 by "PERL_ANYEVENT_MODEL", or a guard callback throwing an exception
1242 - this is the minimum recommended level for use during development.
1124 1243
1125 When set to 2 or higher, cause AnyEvent to report to STDERR which 1244 When set to 7 or higher (info), AnyEvent reports which event model
1126 event model it chooses. 1245 it chooses.
1127 1246
1128 When set to 8 or higher, then AnyEvent will report extra information 1247 When set to 8 or higher (debug), then AnyEvent will report extra
1129 on which optional modules it loads and how it implements certain 1248 information on which optional modules it loads and how it implements
1130 features. 1249 certain features.
1250
1251 "PERL_ANYEVENT_LOG"
1252 Accepts rather complex logging specifications. For example, you
1253 could log all "debug" messages of some module to stderr, warnings
1254 and above to stderr, and errors and above to syslog, with:
1255
1256 PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
1257
1258 For the rather extensive details, see AnyEvent::Log.
1259
1260 This variable is evaluated when AnyEvent (or AnyEvent::Log) is
1261 loaded, so will take effect even before AnyEvent has initialised
1262 itself.
1263
1264 Note that specifying this environment variable causes the
1265 AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE"
1266 does not, so only using the latter saves a few hundred kB of memory
1267 unless a module explicitly needs the extra features of
1268 AnyEvent::Log.
1131 1269
1132 "PERL_ANYEVENT_STRICT" 1270 "PERL_ANYEVENT_STRICT"
1133 AnyEvent does not do much argument checking by default, as thorough 1271 AnyEvent does not do much argument checking by default, as thorough
1134 argument checking is very costly. Setting this variable to a true 1272 argument checking is very costly. Setting this variable to a true
1135 value will cause AnyEvent to load "AnyEvent::Strict" and then to 1273 value will cause AnyEvent to load "AnyEvent::Strict" and then to
… …
1141 Unlike "use strict" (or its modern cousin, "use common::sense", it 1279 Unlike "use strict" (or its modern cousin, "use common::sense", it
1142 is definitely recommended to keep it off in production. Keeping 1280 is definitely recommended to keep it off in production. Keeping
1143 "PERL_ANYEVENT_STRICT=1" in your environment while developing 1281 "PERL_ANYEVENT_STRICT=1" in your environment while developing
1144 programs can be very useful, however. 1282 programs can be very useful, however.
1145 1283
1284 "PERL_ANYEVENT_DEBUG_SHELL"
1285 If this env variable is nonempty, then its contents will be
1286 interpreted by "AnyEvent::Socket::parse_hostport" and
1287 "AnyEvent::Debug::shell" (after replacing every occurance of $$ by
1288 the process pid). The shell object is saved in
1289 $AnyEvent::Debug::SHELL.
1290
1291 This happens when the first watcher is created.
1292
1293 For example, to bind a debug shell on a unix domain socket in
1294 /tmp/debug<pid>.sock, you could use this:
1295
1296 PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
1297 # connect with e.g.: socat readline /tmp/debug123.sock
1298
1299 Or to bind to tcp port 4545 on localhost:
1300
1301 PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
1302 # connect with e.g.: telnet localhost 4545
1303
1304 Note that creating sockets in /tmp or on localhost is very unsafe on
1305 multiuser systems.
1306
1307 "PERL_ANYEVENT_DEBUG_WRAP"
1308 Can be set to 0, 1 or 2 and enables wrapping of all watchers for
1309 debugging purposes. See "AnyEvent::Debug::wrap" for details.
1310
1146 "PERL_ANYEVENT_MODEL" 1311 "PERL_ANYEVENT_MODEL"
1147 This can be used to specify the event model to be used by AnyEvent, 1312 This can be used to specify the event model to be used by AnyEvent,
1148 before auto detection and -probing kicks in. It must be a string 1313 before auto detection and -probing kicks in.
1149 consisting entirely of ASCII letters. The string "AnyEvent::Impl::" 1314
1150 gets prepended and the resulting module name is loaded and if the 1315 It normally is a string consisting entirely of ASCII letters (e.g.
1151 load was successful, used as event model. If it fails to load 1316 "EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and
1317 the resulting module name is loaded and - if the load was successful
1318 - used as event model backend. If it fails to load then AnyEvent
1152 AnyEvent will proceed with auto detection and -probing. 1319 will proceed with auto detection and -probing.
1153 1320
1154 This functionality might change in future versions. 1321 If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::")
1322 then nothing gets prepended and the module name is used as-is (hint:
1323 "::" at the end of a string designates a module name and quotes it
1324 appropriately).
1155 1325
1156 For example, to force the pure perl model (AnyEvent::Impl::Perl) you 1326 For example, to force the pure perl model (AnyEvent::Loop::Perl) you
1157 could start your program like this: 1327 could start your program like this:
1158 1328
1159 PERL_ANYEVENT_MODEL=Perl perl ... 1329 PERL_ANYEVENT_MODEL=Perl perl ...
1330
1331 "PERL_ANYEVENT_IO_MODEL"
1332 The current file I/O model - see AnyEvent::IO for more info.
1333
1334 At the moment, only "Perl" (small, pure-perl, synchronous) and
1335 "IOAIO" (truly asynchronous) are supported. The default is "IOAIO"
1336 if AnyEvent::AIO can be loaded, otherwise it is "Perl".
1160 1337
1161 "PERL_ANYEVENT_PROTOCOLS" 1338 "PERL_ANYEVENT_PROTOCOLS"
1162 Used by both AnyEvent::DNS and AnyEvent::Socket to determine 1339 Used by both AnyEvent::DNS and AnyEvent::Socket to determine
1163 preferences for IPv4 or IPv6. The default is unspecified (and might 1340 preferences for IPv4 or IPv6. The default is unspecified (and might
1164 change, or be the result of auto probing). 1341 change, or be the result of auto probing).
… …
1178 "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to 1355 "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to
1179 resolve or contact IPv6 addresses. 1356 resolve or contact IPv6 addresses.
1180 "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but 1357 "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but
1181 prefer IPv6 over IPv4. 1358 prefer IPv6 over IPv4.
1182 1359
1360 "PERL_ANYEVENT_HOSTS"
1361 This variable, if specified, overrides the /etc/hosts file used by
1362 AnyEvent::Socket"::resolve_sockaddr", i.e. hosts aliases will be
1363 read from that file instead.
1364
1183 "PERL_ANYEVENT_EDNS0" 1365 "PERL_ANYEVENT_EDNS0"
1184 Used by AnyEvent::DNS to decide whether to use the EDNS0 extension 1366 Used by AnyEvent::DNS to decide whether to use the EDNS0 extension
1185 for DNS. This extension is generally useful to reduce DNS traffic, 1367 for DNS. This extension is generally useful to reduce DNS traffic,
1186 but some (broken) firewalls drop such DNS packets, which is why it 1368 especially when DNSSEC is involved, but some (broken) firewalls drop
1187 is off by default. 1369 such DNS packets, which is why it is off by default.
1188 1370
1189 Setting this variable to 1 will cause AnyEvent::DNS to announce 1371 Setting this variable to 1 will cause AnyEvent::DNS to announce
1190 EDNS0 in its DNS requests. 1372 EDNS0 in its DNS requests.
1191 1373
1192 "PERL_ANYEVENT_MAX_FORKS" 1374 "PERL_ANYEVENT_MAX_FORKS"
… …
1196 "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" 1378 "PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
1197 The default value for the "max_outstanding" parameter for the 1379 The default value for the "max_outstanding" parameter for the
1198 default DNS resolver - this is the maximum number of parallel DNS 1380 default DNS resolver - this is the maximum number of parallel DNS
1199 requests that are sent to the DNS server. 1381 requests that are sent to the DNS server.
1200 1382
1383 "PERL_ANYEVENT_MAX_SIGNAL_LATENCY"
1384 Perl has inherently racy signal handling (you can basically choose
1385 between losing signals and memory corruption) - pure perl event
1386 loops (including "AnyEvent::Loop", when "Async::Interrupt" isn't
1387 available) therefore have to poll regularly to avoid losing signals.
1388
1389 Some event loops are racy, but don't poll regularly, and some event
1390 loops are written in C but are still racy. For those event loops,
1391 AnyEvent installs a timer that regularly wakes up the event loop.
1392
1393 By default, the interval for this timer is 10 seconds, but you can
1394 override this delay with this environment variable (or by setting
1395 the $AnyEvent::MAX_SIGNAL_LATENCY variable before creating signal
1396 watchers).
1397
1398 Lower values increase CPU (and energy) usage, higher values can
1399 introduce long delays when reaping children or waiting for signals.
1400
1401 The AnyEvent::Async module, if available, will be used to avoid this
1402 polling (with most event loops).
1403
1201 "PERL_ANYEVENT_RESOLV_CONF" 1404 "PERL_ANYEVENT_RESOLV_CONF"
1202 The file to use instead of /etc/resolv.conf (or OS-specific 1405 The absolute path to a resolv.conf-style file to use instead of
1203 configuration) in the default resolver. When set to the empty 1406 /etc/resolv.conf (or the OS-specific configuration) in the default
1204 string, no default config will be used. 1407 resolver, or the empty string to select the default configuration.
1205 1408
1206 "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". 1409 "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
1207 When neither "ca_file" nor "ca_path" was specified during 1410 When neither "ca_file" nor "ca_path" was specified during
1208 AnyEvent::TLS context creation, and either of these environment 1411 AnyEvent::TLS context creation, and either of these environment
1209 variables exist, they will be used to specify CA certificate 1412 variables are nonempty, they will be used to specify CA certificate
1210 locations instead of a system-dependent default. 1413 locations instead of a system-dependent default.
1211 1414
1212 "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" 1415 "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"
1213 When these are set to 1, then the respective modules are not loaded. 1416 When these are set to 1, then the respective modules are not loaded.
1214 Mostly good for testing AnyEvent itself. 1417 Mostly good for testing AnyEvent itself.
… …
1534 when used without AnyEvent), but most event loops have acceptable 1737 when used without AnyEvent), but most event loops have acceptable
1535 performance with or without AnyEvent. 1738 performance with or without AnyEvent.
1536 1739
1537 * The overhead AnyEvent adds is usually much smaller than the overhead 1740 * The overhead AnyEvent adds is usually much smaller than the overhead
1538 of the actual event loop, only with extremely fast event loops such 1741 of the actual event loop, only with extremely fast event loops such
1539 as EV adds AnyEvent significant overhead. 1742 as EV does AnyEvent add significant overhead.
1540 1743
1541 * You should avoid POE like the plague if you want performance or 1744 * You should avoid POE like the plague if you want performance or
1542 reasonable memory usage. 1745 reasonable memory usage.
1543 1746
1544 BENCHMARKING THE LARGE SERVER CASE 1747 BENCHMARKING THE LARGE SERVER CASE
… …
1804 the help of AnyEvent::TLS), gains the ability to do TLS/SSL. 2007 the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
1805 2008
1806 Time::HiRes 2009 Time::HiRes
1807 This module is part of perl since release 5.008. It will be used 2010 This module is part of perl since release 5.008. It will be used
1808 when the chosen event library does not come with a timing source of 2011 when the chosen event library does not come with a timing source of
1809 its own. The pure-perl event loop (AnyEvent::Impl::Perl) will 2012 its own. The pure-perl event loop (AnyEvent::Loop) will additionally
1810 additionally use it to try to use a monotonic clock for timing 2013 load it to try to use a monotonic clock for timing stability.
1811 stability. 2014
2015 AnyEvent::AIO (and IO::AIO)
2016 The default implementation of AnyEvent::IO is to do I/O
2017 synchronously, stopping programs while they access the disk, which
2018 is fine for a lot of programs.
2019
2020 Installing AnyEvent::AIO (and its IO::AIO dependency) makes it
2021 switch to a true asynchronous implementation, so event processing
2022 can continue even while waiting for disk I/O.
1812 2023
1813FORK 2024FORK
1814 Most event libraries are not fork-safe. The ones who are usually are 2025 Most event libraries are not fork-safe. The ones who are usually are
1815 because they rely on inefficient but fork-safe "select" or "poll" calls 2026 because they rely on inefficient but fork-safe "select" or "poll" calls
1816 - higher performance APIs such as BSD's kqueue or the dreaded Linux 2027 - higher performance APIs such as BSD's kqueue or the dreaded Linux
… …
1871SEE ALSO 2082SEE ALSO
1872 Tutorial/Introduction: AnyEvent::Intro. 2083 Tutorial/Introduction: AnyEvent::Intro.
1873 2084
1874 FAQ: AnyEvent::FAQ. 2085 FAQ: AnyEvent::FAQ.
1875 2086
1876 Utility functions: AnyEvent::Util. 2087 Utility functions: AnyEvent::Util (misc. grab-bag), AnyEvent::Log
2088 (simply logging).
1877 2089
1878 Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, 2090 Development/Debugging: AnyEvent::Strict (stricter checking),
1879 Event::Lib, Qt, POE. 2091 AnyEvent::Debug (interactive shell, watcher tracing).
2092
2093 Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event,
2094 Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK.
1880 2095
1881 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, 2096 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1882 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, 2097 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1883 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, 2098 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
1884 AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. 2099 AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi, AnyEvent::Impl::FLTK.
1885 2100
1886 Non-blocking file handles, sockets, TCP clients and servers: 2101 Non-blocking handles, pipes, stream sockets, TCP clients and servers:
1887 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. 2102 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
2103
2104 Asynchronous File I/O: AnyEvent::IO.
1888 2105
1889 Asynchronous DNS: AnyEvent::DNS. 2106 Asynchronous DNS: AnyEvent::DNS.
1890 2107
1891 Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. 2108 Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event.
1892 2109
1893 Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, 2110 Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC,
1894 AnyEvent::HTTP. 2111 AnyEvent::HTTP.
1895 2112
1896AUTHOR 2113AUTHOR
1897 Marc Lehmann <schmorp@schmorp.de> 2114 Marc Lehmann <schmorp@schmorp.de>
1898 http://home.schmorp.de/ 2115 http://anyevent.schmorp.de
1899 2116

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