ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/AnyEvent/README
(Generate patch)

Comparing AnyEvent/README (file contents):
Revision 1.63 by root, Wed Oct 13 19:49:46 2010 UTC vs.
Revision 1.70 by root, Fri Apr 13 09:57:41 2012 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
… …
80 that isn't them. What's worse, all the potential users of your module 80 that isn't them. What's worse, all the potential users of your module
81 are *also* forced to use the same event loop you use. 81 are *also* forced to use the same event loop you use.
82 82
83 AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 83 AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
84 fine. AnyEvent + Tk works fine etc. etc. but none of these work together 84 fine. AnyEvent + Tk works fine etc. etc. but none of these work together
85 with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your 85 with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
86 module uses one of those, every user of your module has to use it, too. 86 uses one of those, every user of your module has to use it, too. But if
87 But if your module uses AnyEvent, it works transparently with all event 87 your module uses AnyEvent, it works transparently with all event models
88 models it supports (including stuff like IO::Async, as long as those use 88 it supports (including stuff like IO::Async, as long as those use one of
89 one of the supported event loops. It is easy to add new event loops to 89 the supported event loops. It is easy to add new event loops to
90 AnyEvent, too, so it is future-proof). 90 AnyEvent, too, so it is future-proof).
91 91
92 In addition to being free of having to use *the one and only true event 92 In addition to being free of having to use *the one and only true event
93 model*, AnyEvent also is free of bloat and policy: with POE or similar 93 model*, AnyEvent also is free of bloat and policy: with POE or similar
94 modules, you get an enormous amount of code and strict rules you have to 94 modules, you get an enormous amount of code and strict rules you have to
… …
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.
… …
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
… …
821 use. If EV is not installed, then AnyEvent will fall back to its own 817 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 818 pure-perl implementation, which is available everywhere as it comes
823 with AnyEvent itself. 819 with AnyEvent itself.
824 820
825 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 821 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
826 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 822 AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
827 823
828 Backends that are transparently being picked up when they are used. 824 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 825 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 826 is created, in which case it is assumed that the application is
831 using them. This means that AnyEvent will automatically pick the 827 using them. This means that AnyEvent will automatically pick the
… …
837 AnyEvent::Impl::Glib based on Glib, slow but very stable. 833 AnyEvent::Impl::Glib based on Glib, slow but very stable.
838 AnyEvent::Impl::Tk based on Tk, very broken. 834 AnyEvent::Impl::Tk based on Tk, very broken.
839 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 835 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
840 AnyEvent::Impl::POE based on POE, very slow, some limitations. 836 AnyEvent::Impl::POE based on POE, very slow, some limitations.
841 AnyEvent::Impl::Irssi used when running within irssi. 837 AnyEvent::Impl::Irssi used when running within irssi.
838 AnyEvent::Impl::IOAsync based on IO::Async.
839 AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
840 AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
842 841
843 Backends with special needs. 842 Backends with special needs.
844 Qt requires the Qt::Application to be instantiated first, but will 843 Qt requires the Qt::Application to be instantiated first, but will
845 otherwise be picked up automatically. As long as the main program 844 otherwise be picked up automatically. As long as the main program
846 instantiates the application before any AnyEvent watchers are 845 instantiates the application before any AnyEvent watchers are
847 created, everything should just work. 846 created, everything should just work.
848 847
849 AnyEvent::Impl::Qt based on Qt. 848 AnyEvent::Impl::Qt based on Qt.
850
851 Support for IO::Async can only be partial, as it is too broken and
852 architecturally limited to even support the AnyEvent API. It also is
853 the only event loop that needs the loop to be set explicitly, so it
854 can only be used by a main program knowing about AnyEvent. See
855 AnyEvent::Impl::IOAsync for the gory details.
856
857 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
858 849
859 Event loops that are indirectly supported via other backends. 850 Event loops that are indirectly supported via other backends.
860 Some event loops can be supported via other modules: 851 Some event loops can be supported via other modules:
861 852
862 There is no direct support for WxWidgets (Wx) or Prima. 853 There is no direct support for WxWidgets (Wx) or Prima.
… …
891 Returns $AnyEvent::MODEL, forcing autodetection of the event model 882 Returns $AnyEvent::MODEL, forcing autodetection of the event model
892 if necessary. You should only call this function right before you 883 if necessary. You should only call this function right before you
893 would have created an AnyEvent watcher anyway, that is, as late as 884 would have created an AnyEvent watcher anyway, that is, as late as
894 possible at runtime, and not e.g. during initialisation of your 885 possible at runtime, and not e.g. during initialisation of your
895 module. 886 module.
887
888 The effect of calling this function is as if a watcher had been
889 created (specifically, actions that happen "when the first watcher
890 is created" happen when calling detetc as well).
896 891
897 If you need to do some initialisation before AnyEvent watchers are 892 If you need to do some initialisation before AnyEvent watchers are
898 created, use "post_detect". 893 created, use "post_detect".
899 894
900 $guard = AnyEvent::post_detect { BLOCK } 895 $guard = AnyEvent::post_detect { BLOCK }
… …
962 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent 957 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
963 # as soon as it is 958 # as soon as it is
964 push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; 959 push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
965 } 960 }
966 961
962 AnyEvent::postpone { BLOCK }
963 Arranges for the block to be executed as soon as possible, but not
964 before the call itself returns. In practise, the block will be
965 executed just before the event loop polls for new events, or shortly
966 afterwards.
967
968 This function never returns anything (to make the "return postpone {
969 ... }" idiom more useful.
970
971 To understand the usefulness of this function, consider a function
972 that asynchronously does something for you and returns some
973 transaction object or guard to let you cancel the operation. For
974 example, "AnyEvent::Socket::tcp_connect":
975
976 # start a conenction attempt unless one is active
977 $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
978 delete $self->{connect_guard};
979 ...
980 };
981
982 Imagine that this function could instantly call the callback, for
983 example, because it detects an obvious error such as a negative port
984 number. Invoking the callback before the function returns causes
985 problems however: the callback will be called and will try to delete
986 the guard object. But since the function hasn't returned yet, there
987 is nothing to delete. When the function eventually returns it will
988 assign the guard object to "$self->{connect_guard}", where it will
989 likely never be deleted, so the program thinks it is still trying to
990 connect.
991
992 This is where "AnyEvent::postpone" should be used. Instead of
993 calling the callback directly on error:
994
995 $cb->(undef), return # signal error to callback, BAD!
996 if $some_error_condition;
997
998 It should use "postpone":
999
1000 AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
1001 if $some_error_condition;
1002
1003 AnyEvent::log $level, $msg[, @args]
1004 Log the given $msg at the given $level.
1005
1006 If AnyEvent::Log is not loaded then this function makes a simple
1007 test to see whether the message will be logged. If the test succeeds
1008 it will load AnyEvent::Log and call "AnyEvent::Log::log" -
1009 consequently, look at the AnyEvent::Log documentation for details.
1010
1011 If the test fails it will simply return. Right now this happens when
1012 a numerical loglevel is used and it is larger than the level
1013 specified via $ENV{PERL_ANYEVENT_VERBOSE}.
1014
1015 If you want to sprinkle loads of logging calls around your code,
1016 consider creating a logger callback with the "AnyEvent::Log::logger"
1017 function, which can reduce typing, codesize and can reduce the
1018 logging overhead enourmously.
1019
967WHAT TO DO IN A MODULE 1020WHAT TO DO IN A MODULE
968 As a module author, you should "use AnyEvent" and call AnyEvent methods 1021 As a module author, you should "use AnyEvent" and call AnyEvent methods
969 freely, but you should not load a specific event module or rely on it. 1022 freely, but you should not load a specific event module or rely on it.
970 1023
971 Be careful when you create watchers in the module body - AnyEvent will 1024 Be careful when you create watchers in the module body - AnyEvent will
… …
1001 will decide on the event model to use as soon as it creates watchers, 1054 will decide on the event model to use as soon as it creates watchers,
1002 and it might choose the wrong one unless you load the correct one 1055 and it might choose the wrong one unless you load the correct one
1003 yourself. 1056 yourself.
1004 1057
1005 You can chose to use a pure-perl implementation by loading the 1058 You can chose to use a pure-perl implementation by loading the
1006 "AnyEvent::Impl::Perl" module, which gives you similar behaviour 1059 "AnyEvent::Loop" module, which gives you similar behaviour everywhere,
1007 everywhere, but letting AnyEvent chose the model is generally better. 1060 but letting AnyEvent chose the model is generally better.
1008 1061
1009 MAINLOOP EMULATION 1062 MAINLOOP EMULATION
1010 Sometimes (often for short test scripts, or even standalone programs who 1063 Sometimes (often for short test scripts, or even standalone programs who
1011 only want to use AnyEvent), you do not want to run a specific event 1064 only want to use AnyEvent), you do not want to run a specific event
1012 loop. 1065 loop.
… …
1024 1077
1025OTHER MODULES 1078OTHER MODULES
1026 The following is a non-exhaustive list of additional modules that use 1079 The following is a non-exhaustive list of additional modules that use
1027 AnyEvent as a client and can therefore be mixed easily with other 1080 AnyEvent as a client and can therefore be mixed easily with other
1028 AnyEvent modules and other event loops in the same program. Some of the 1081 AnyEvent modules and other event loops in the same program. Some of the
1029 modules come as part of AnyEvent, the others are available via CPAN. 1082 modules come as part of AnyEvent, the others are available via CPAN (see
1083 <http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for a longer
1084 non-exhaustive list), and the list is heavily biased towards modules of
1085 the AnyEvent author himself :)
1030 1086
1031 AnyEvent::Util 1087 AnyEvent::Util
1032 Contains various utility functions that replace often-used blocking 1088 Contains various utility functions that replace often-used blocking
1033 functions such as "inet_aton" with event/callback-based versions. 1089 functions such as "inet_aton" with event/callback-based versions.
1034 1090
… …
1050 AnyEvent::IGS, AnyEvent::FCP 1106 AnyEvent::IGS, AnyEvent::FCP
1051 Implement event-based interfaces to the protocols of the same name 1107 Implement event-based interfaces to the protocols of the same name
1052 (for the curious, IGS is the International Go Server and FCP is the 1108 (for the curious, IGS is the International Go Server and FCP is the
1053 Freenet Client Protocol). 1109 Freenet Client Protocol).
1054 1110
1055 AnyEvent::Handle::UDP
1056 Here be danger!
1057
1058 As Pauli would put it, "Not only is it not right, it's not even
1059 wrong!" - there are so many things wrong with AnyEvent::Handle::UDP,
1060 most notably its use of a stream-based API with a protocol that
1061 isn't streamable, that the only way to improve it is to delete it.
1062
1063 It features data corruption (but typically only under load) and
1064 general confusion. On top, the author is not only clueless about UDP
1065 but also fact-resistant - some gems of his understanding: "connect
1066 doesn't work with UDP", "UDP packets are not IP packets", "UDP only
1067 has datagrams, not packets", "I don't need to implement proper error
1068 checking as UDP doesn't support error checking" and so on - he
1069 doesn't even understand what's wrong with his module when it is
1070 explained to him.
1071
1072 AnyEvent::DBI
1073 Executes DBI requests asynchronously in a proxy process for you,
1074 notifying you in an event-based way when the operation is finished.
1075
1076 AnyEvent::AIO 1111 AnyEvent::AIO
1077 Truly asynchronous (as opposed to non-blocking) I/O, should be in 1112 Truly asynchronous (as opposed to non-blocking) I/O, should be in
1078 the toolbox of every event programmer. AnyEvent::AIO transparently 1113 the toolbox of every event programmer. AnyEvent::AIO transparently
1079 fuses IO::AIO and AnyEvent together, giving AnyEvent access to 1114 fuses IO::AIO and AnyEvent together, giving AnyEvent access to
1080 event-based file I/O, and much more. 1115 event-based file I/O, and much more.
1081 1116
1117 AnyEvent::Filesys::Notify
1118 AnyEvent is good for non-blocking stuff, but it can't detect file or
1119 path changes (e.g. "watch this directory for new files", "watch this
1120 file for changes"). The AnyEvent::Filesys::Notify module promises to
1121 do just that in a portbale fashion, supporting inotify on GNU/Linux
1122 and some weird, without doubt broken, stuff on OS X to monitor
1123 files. It can fall back to blocking scans at regular intervals
1124 transparently on other platforms, so it's about as portable as it
1125 gets.
1126
1127 (I haven't used it myself, but I haven't heard anybody complaining
1128 about it yet).
1129
1130 AnyEvent::DBI
1131 Executes DBI requests asynchronously in a proxy process for you,
1132 notifying you in an event-based way when the operation is finished.
1133
1082 AnyEvent::HTTPD 1134 AnyEvent::HTTPD
1083 A simple embedded webserver. 1135 A simple embedded webserver.
1084 1136
1085 AnyEvent::FastPing 1137 AnyEvent::FastPing
1086 The fastest ping in the west. 1138 The fastest ping in the west.
1087 1139
1088 Coro 1140 Coro
1089 Has special support for AnyEvent via Coro::AnyEvent. 1141 Has special support for AnyEvent via Coro::AnyEvent, which allows
1142 you to simply invert the flow control - don't call us, we will call
1143 you:
1144
1145 async {
1146 Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
1147 print "5 seconds later!\n";
1148
1149 Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
1150 my $line = <STDIN>; # works for ttys
1151
1152 AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
1153 my ($body, $hdr) = Coro::rouse_wait;
1154 };
1090 1155
1091SIMPLIFIED AE API 1156SIMPLIFIED AE API
1092 Starting with version 5.0, AnyEvent officially supports a second, much 1157 Starting with version 5.0, AnyEvent officially supports a second, much
1093 simpler, API that is designed to reduce the calling, typing and memory 1158 simpler, API that is designed to reduce the calling, typing and memory
1094 overhead by using function call syntax and a fixed number of parameters. 1159 overhead by using function call syntax and a fixed number of parameters.
… …
1110 The pure perl event loop simply re-throws the exception (usually within 1175 The pure perl event loop simply re-throws the exception (usually within
1111 "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", 1176 "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
1112 Glib uses "install_exception_handler" and so on. 1177 Glib uses "install_exception_handler" and so on.
1113 1178
1114ENVIRONMENT VARIABLES 1179ENVIRONMENT VARIABLES
1115 The following environment variables are used by this module or its 1180 AnyEvent supports a number of environment variables that tune the
1116 submodules. 1181 runtime behaviour. They are usually evaluated when AnyEvent is loaded,
1182 initialised, or a submodule that uses them is loaded. Many of them also
1183 cause AnyEvent to load additional modules - for example,
1184 "PERL_ANYEVENT_DEBUG_WRAP" causes the AnyEvent::Debug module to be
1185 loaded.
1117 1186
1118 Note that AnyEvent will remove *all* environment variables starting with 1187 All the environment variables documented here start with
1119 "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is 1188 "PERL_ANYEVENT_", which is what AnyEvent considers its own namespace.
1120 enabled. 1189 Other modules are encouraged (but by no means required) to use
1190 "PERL_ANYEVENT_SUBMODULE" if they have registered the
1191 AnyEvent::Submodule namespace on CPAN, for any submodule. For example,
1192 AnyEvent::HTTP could be expected to use "PERL_ANYEVENT_HTTP_PROXY" (it
1193 should not access env variables starting with "AE_", see below).
1194
1195 All variables can also be set via the "AE_" prefix, that is, instead of
1196 setting "PERL_ANYEVENT_VERBOSE" you can also set "AE_VERBOSE". In case
1197 there is a clash btween anyevent and another program that uses
1198 "AE_something" you can set the corresponding "PERL_ANYEVENT_something"
1199 variable to the empty string, as those variables take precedence.
1200
1201 When AnyEvent is first loaded, it copies all "AE_xxx" env variables to
1202 their "PERL_ANYEVENT_xxx" counterpart unless that variable already
1203 exists. If taint mode is on, then AnyEvent will remove *all* environment
1204 variables starting with "PERL_ANYEVENT_" from %ENV (or replace them with
1205 "undef" or the empty string, if the corresaponding "AE_" variable is
1206 set).
1207
1208 The exact algorithm is currently:
1209
1210 1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
1211 2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
1212 3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
1213
1214 This ensures that child processes will not see the "AE_" variables.
1215
1216 The following environment variables are currently known to AnyEvent:
1121 1217
1122 "PERL_ANYEVENT_VERBOSE" 1218 "PERL_ANYEVENT_VERBOSE"
1123 By default, AnyEvent will be completely silent except in fatal 1219 By default, AnyEvent will log messages with loglevel 4 ("error") or
1124 conditions. You can set this environment variable to make AnyEvent 1220 higher (see AnyEvent::Log). You can set this environment variable to
1125 more talkative. 1221 a numerical loglevel to make AnyEvent more (or less) talkative.
1126 1222
1223 If you want to do more than just set the global logging level you
1224 should have a look at "PERL_ANYEVENT_LOG", which allows much more
1225 complex specifications.
1226
1227 When set to 0 ("off"), then no messages whatsoever will be logged
1228 with everything else at defaults.
1229
1127 When set to 1 or higher, causes AnyEvent to warn about unexpected 1230 When set to 5 or higher ("warn"), AnyEvent warns about unexpected
1128 conditions, such as not being able to load the event model specified 1231 conditions, such as not being able to load the event model specified
1129 by "PERL_ANYEVENT_MODEL". 1232 by "PERL_ANYEVENT_MODEL", or a guard callback throwing an exception
1233 - this is the minimum recommended level for use during development.
1130 1234
1131 When set to 2 or higher, cause AnyEvent to report to STDERR which 1235 When set to 7 or higher (info), AnyEvent reports which event model
1132 event model it chooses. 1236 it chooses.
1133 1237
1134 When set to 8 or higher, then AnyEvent will report extra information 1238 When set to 8 or higher (debug), then AnyEvent will report extra
1135 on which optional modules it loads and how it implements certain 1239 information on which optional modules it loads and how it implements
1136 features. 1240 certain features.
1241
1242 "PERL_ANYEVENT_LOG"
1243 Accepts rather complex logging specifications. For example, you
1244 could log all "debug" messages of some module to stderr, warnings
1245 and above to stderr, and errors and above to syslog, with:
1246
1247 PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
1248
1249 For the rather extensive details, see AnyEvent::Log.
1250
1251 This variable is evaluated when AnyEvent (or AnyEvent::Log) is
1252 loaded, so will take effect even before AnyEvent has initialised
1253 itself.
1254
1255 Note that specifying this environment variable causes the
1256 AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE"
1257 does not, so only using the latter saves a few hundred kB of memory
1258 unless a module explicitly needs the extra features of
1259 AnyEvent::Log.
1137 1260
1138 "PERL_ANYEVENT_STRICT" 1261 "PERL_ANYEVENT_STRICT"
1139 AnyEvent does not do much argument checking by default, as thorough 1262 AnyEvent does not do much argument checking by default, as thorough
1140 argument checking is very costly. Setting this variable to a true 1263 argument checking is very costly. Setting this variable to a true
1141 value will cause AnyEvent to load "AnyEvent::Strict" and then to 1264 value will cause AnyEvent to load "AnyEvent::Strict" and then to
… …
1147 Unlike "use strict" (or its modern cousin, "use common::sense", it 1270 Unlike "use strict" (or its modern cousin, "use common::sense", it
1148 is definitely recommended to keep it off in production. Keeping 1271 is definitely recommended to keep it off in production. Keeping
1149 "PERL_ANYEVENT_STRICT=1" in your environment while developing 1272 "PERL_ANYEVENT_STRICT=1" in your environment while developing
1150 programs can be very useful, however. 1273 programs can be very useful, however.
1151 1274
1275 "PERL_ANYEVENT_DEBUG_SHELL"
1276 If this env variable is nonempty, then its contents will be
1277 interpreted by "AnyEvent::Socket::parse_hostport" and
1278 "AnyEvent::Debug::shell" (after replacing every occurance of $$ by
1279 the process pid). The shell object is saved in
1280 $AnyEvent::Debug::SHELL.
1281
1282 This happens when the first watcher is created.
1283
1284 For example, to bind a debug shell on a unix domain socket in
1285 /tmp/debug<pid>.sock, you could use this:
1286
1287 PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
1288 # connect with e.g.: socat readline /tmp/debug123.sock
1289
1290 Or to bind to tcp port 4545 on localhost:
1291
1292 PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
1293 # connect with e.g.: telnet localhost 4545
1294
1295 Note that creating sockets in /tmp or on localhost is very unsafe on
1296 multiuser systems.
1297
1298 "PERL_ANYEVENT_DEBUG_WRAP"
1299 Can be set to 0, 1 or 2 and enables wrapping of all watchers for
1300 debugging purposes. See "AnyEvent::Debug::wrap" for details.
1301
1152 "PERL_ANYEVENT_MODEL" 1302 "PERL_ANYEVENT_MODEL"
1153 This can be used to specify the event model to be used by AnyEvent, 1303 This can be used to specify the event model to be used by AnyEvent,
1154 before auto detection and -probing kicks in. It must be a string 1304 before auto detection and -probing kicks in.
1155 consisting entirely of ASCII letters. The string "AnyEvent::Impl::" 1305
1156 gets prepended and the resulting module name is loaded and if the 1306 It normally is a string consisting entirely of ASCII letters (e.g.
1157 load was successful, used as event model. If it fails to load 1307 "EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and
1308 the resulting module name is loaded and - if the load was successful
1309 - used as event model backend. If it fails to load then AnyEvent
1158 AnyEvent will proceed with auto detection and -probing. 1310 will proceed with auto detection and -probing.
1159 1311
1160 This functionality might change in future versions. 1312 If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::")
1313 then nothing gets prepended and the module name is used as-is (hint:
1314 "::" at the end of a string designates a module name and quotes it
1315 appropriately).
1161 1316
1162 For example, to force the pure perl model (AnyEvent::Impl::Perl) you 1317 For example, to force the pure perl model (AnyEvent::Loop::Perl) you
1163 could start your program like this: 1318 could start your program like this:
1164 1319
1165 PERL_ANYEVENT_MODEL=Perl perl ... 1320 PERL_ANYEVENT_MODEL=Perl perl ...
1321
1322 "PERL_ANYEVENT_IO_MODEL"
1323 The current file I/O model - see AnyEvent::IO for more info.
1324
1325 At the moment, only "Perl" (small, pure-perl, synchronous) and
1326 "IOAIO" (truly asynchronous) are supported. The default is "IOAIO"
1327 if AnyEvent::AIO can be loaded, otherwise it is "Perl".
1166 1328
1167 "PERL_ANYEVENT_PROTOCOLS" 1329 "PERL_ANYEVENT_PROTOCOLS"
1168 Used by both AnyEvent::DNS and AnyEvent::Socket to determine 1330 Used by both AnyEvent::DNS and AnyEvent::Socket to determine
1169 preferences for IPv4 or IPv6. The default is unspecified (and might 1331 preferences for IPv4 or IPv6. The default is unspecified (and might
1170 change, or be the result of auto probing). 1332 change, or be the result of auto probing).
… …
1184 "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to 1346 "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to
1185 resolve or contact IPv6 addresses. 1347 resolve or contact IPv6 addresses.
1186 "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but 1348 "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but
1187 prefer IPv6 over IPv4. 1349 prefer IPv6 over IPv4.
1188 1350
1351 "PERL_ANYEVENT_HOSTS"
1352 This variable, if specified, overrides the /etc/hosts file used by
1353 AnyEvent::Socket"::resolve_sockaddr", i.e. hosts aliases will be
1354 read from that file instead.
1355
1189 "PERL_ANYEVENT_EDNS0" 1356 "PERL_ANYEVENT_EDNS0"
1190 Used by AnyEvent::DNS to decide whether to use the EDNS0 extension 1357 Used by AnyEvent::DNS to decide whether to use the EDNS0 extension
1191 for DNS. This extension is generally useful to reduce DNS traffic, 1358 for DNS. This extension is generally useful to reduce DNS traffic,
1192 but some (broken) firewalls drop such DNS packets, which is why it 1359 especially when DNSSEC is involved, but some (broken) firewalls drop
1193 is off by default. 1360 such DNS packets, which is why it is off by default.
1194 1361
1195 Setting this variable to 1 will cause AnyEvent::DNS to announce 1362 Setting this variable to 1 will cause AnyEvent::DNS to announce
1196 EDNS0 in its DNS requests. 1363 EDNS0 in its DNS requests.
1197 1364
1198 "PERL_ANYEVENT_MAX_FORKS" 1365 "PERL_ANYEVENT_MAX_FORKS"
… …
1202 "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" 1369 "PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
1203 The default value for the "max_outstanding" parameter for the 1370 The default value for the "max_outstanding" parameter for the
1204 default DNS resolver - this is the maximum number of parallel DNS 1371 default DNS resolver - this is the maximum number of parallel DNS
1205 requests that are sent to the DNS server. 1372 requests that are sent to the DNS server.
1206 1373
1374 "PERL_ANYEVENT_MAX_SIGNAL_LATENCY"
1375 Perl has inherently racy signal handling (you can basically choose
1376 between losing signals and memory corruption) - pure perl event
1377 loops (including "AnyEvent::Loop", when "Async::Interrupt" isn't
1378 available) therefore have to poll regularly to avoid losing signals.
1379
1380 Some event loops are racy, but don't poll regularly, and some event
1381 loops are written in C but are still racy. For those event loops,
1382 AnyEvent installs a timer that regularly wakes up the event loop.
1383
1384 By default, the interval for this timer is 10 seconds, but you can
1385 override this delay with this environment variable (or by setting
1386 the $AnyEvent::MAX_SIGNAL_LATENCY variable before creating signal
1387 watchers).
1388
1389 Lower values increase CPU (and energy) usage, higher values can
1390 introduce long delays when reaping children or waiting for signals.
1391
1392 The AnyEvent::Async module, if available, will be used to avoid this
1393 polling (with most event loops).
1394
1207 "PERL_ANYEVENT_RESOLV_CONF" 1395 "PERL_ANYEVENT_RESOLV_CONF"
1208 The file to use instead of /etc/resolv.conf (or OS-specific 1396 The absolute path to a resolv.conf-style file to use instead of
1209 configuration) in the default resolver. When set to the empty 1397 /etc/resolv.conf (or the OS-specific configuration) in the default
1210 string, no default config will be used. 1398 resolver, or the empty string to select the default configuration.
1211 1399
1212 "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". 1400 "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
1213 When neither "ca_file" nor "ca_path" was specified during 1401 When neither "ca_file" nor "ca_path" was specified during
1214 AnyEvent::TLS context creation, and either of these environment 1402 AnyEvent::TLS context creation, and either of these environment
1215 variables exist, they will be used to specify CA certificate 1403 variables are nonempty, they will be used to specify CA certificate
1216 locations instead of a system-dependent default. 1404 locations instead of a system-dependent default.
1217 1405
1218 "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" 1406 "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"
1219 When these are set to 1, then the respective modules are not loaded. 1407 When these are set to 1, then the respective modules are not loaded.
1220 Mostly good for testing AnyEvent itself. 1408 Mostly good for testing AnyEvent itself.
… …
1540 when used without AnyEvent), but most event loops have acceptable 1728 when used without AnyEvent), but most event loops have acceptable
1541 performance with or without AnyEvent. 1729 performance with or without AnyEvent.
1542 1730
1543 * The overhead AnyEvent adds is usually much smaller than the overhead 1731 * The overhead AnyEvent adds is usually much smaller than the overhead
1544 of the actual event loop, only with extremely fast event loops such 1732 of the actual event loop, only with extremely fast event loops such
1545 as EV adds AnyEvent significant overhead. 1733 as EV does AnyEvent add significant overhead.
1546 1734
1547 * You should avoid POE like the plague if you want performance or 1735 * You should avoid POE like the plague if you want performance or
1548 reasonable memory usage. 1736 reasonable memory usage.
1549 1737
1550 BENCHMARKING THE LARGE SERVER CASE 1738 BENCHMARKING THE LARGE SERVER CASE
… …
1810 the help of AnyEvent::TLS), gains the ability to do TLS/SSL. 1998 the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
1811 1999
1812 Time::HiRes 2000 Time::HiRes
1813 This module is part of perl since release 5.008. It will be used 2001 This module is part of perl since release 5.008. It will be used
1814 when the chosen event library does not come with a timing source of 2002 when the chosen event library does not come with a timing source of
1815 its own. The pure-perl event loop (AnyEvent::Impl::Perl) will 2003 its own. The pure-perl event loop (AnyEvent::Loop) will additionally
1816 additionally use it to try to use a monotonic clock for timing 2004 load it to try to use a monotonic clock for timing stability.
1817 stability.
1818 2005
1819FORK 2006FORK
1820 Most event libraries are not fork-safe. The ones who are usually are 2007 Most event libraries are not fork-safe. The ones who are usually are
1821 because they rely on inefficient but fork-safe "select" or "poll" calls 2008 because they rely on inefficient but fork-safe "select" or "poll" calls
1822 - higher performance APIs such as BSD's kqueue or the dreaded Linux 2009 - higher performance APIs such as BSD's kqueue or the dreaded Linux
… …
1877SEE ALSO 2064SEE ALSO
1878 Tutorial/Introduction: AnyEvent::Intro. 2065 Tutorial/Introduction: AnyEvent::Intro.
1879 2066
1880 FAQ: AnyEvent::FAQ. 2067 FAQ: AnyEvent::FAQ.
1881 2068
1882 Utility functions: AnyEvent::Util. 2069 Utility functions: AnyEvent::Util (misc. grab-bag), AnyEvent::Log
2070 (simply logging).
1883 2071
1884 Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, 2072 Development/Debugging: AnyEvent::Strict (stricter checking),
1885 Event::Lib, Qt, POE. 2073 AnyEvent::Debug (interactive shell, watcher tracing).
2074
2075 Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event,
2076 Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK.
1886 2077
1887 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, 2078 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1888 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, 2079 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1889 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, 2080 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
1890 AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. 2081 AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi, AnyEvent::Impl::FLTK.
1891 2082
1892 Non-blocking file handles, sockets, TCP clients and servers: 2083 Non-blocking handles, pipes, stream sockets, TCP clients and servers:
1893 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. 2084 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
2085
2086 Asynchronous File I/O: AnyEvent::IO.
1894 2087
1895 Asynchronous DNS: AnyEvent::DNS. 2088 Asynchronous DNS: AnyEvent::DNS.
1896 2089
1897 Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. 2090 Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event.
1898 2091
1899 Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, 2092 Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC,
1900 AnyEvent::HTTP. 2093 AnyEvent::HTTP.
1901 2094
1902AUTHOR 2095AUTHOR
1903 Marc Lehmann <schmorp@schmorp.de> 2096 Marc Lehmann <schmorp@schmorp.de>
1904 http://home.schmorp.de/ 2097 http://anyevent.schmorp.de
1905 2098

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines