1 | NAME |
1 | NAME |
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, UV, Perl, Event::Lib, Irssi, rxvt-unicode, |
5 | Qt, FLTK and POE are various supported event loops/environments. |
5 | IO::Async, Qt, FLTK and POE are various supported event |
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6 | loops/environments. |
6 | |
7 | |
7 | SYNOPSIS |
8 | SYNOPSIS |
8 | use AnyEvent; |
9 | use AnyEvent; |
9 | |
10 | |
10 | # if you prefer function calls, look at the AE manpage for |
11 | # if you prefer function calls, look at the AE manpage for |
… | |
… | |
262 | |
263 | |
263 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
264 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
264 | |
265 | |
265 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
266 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
266 | warn "timeout\n"; |
267 | warn "timeout\n"; |
267 | }; |
268 | }); |
268 | |
269 | |
269 | TIMING ISSUES |
270 | TIMING ISSUES |
270 | There are two ways to handle timers: based on real time (relative, "fire |
271 | 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 |
272 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
272 | o'clock"). |
273 | o'clock"). |
… | |
… | |
419 | race-free signal handling in perl, requiring C libraries for this. |
420 | 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 |
421 | 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 10 |
422 | will be delayed. The maximum time a signal might be delayed is 10 |
422 | seconds by default, but can be overriden via |
423 | seconds by default, but can be overriden via |
423 | $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} or $AnyEvent::MAX_SIGNAL_LATENCY |
424 | $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} or $AnyEvent::MAX_SIGNAL_LATENCY |
424 | - see the Ö<ENVIRONMENT VARIABLES> section for details. |
425 | - see the "ENVIRONMENT VARIABLES" section for details. |
425 | |
426 | |
426 | All these problems can be avoided by installing the optional |
427 | All these problems can be avoided by installing the optional |
427 | Async::Interrupt module, which works with most event loops. It will not |
428 | Async::Interrupt module, which works with most event loops. It will not |
428 | work with inherently broken event loops such as Event or Event::Lib (and |
429 | work with inherently broken event loops such as Event or Event::Lib (and |
429 | not with POE currently). For those, you just have to suffer the delays. |
430 | not with POE currently). For those, you just have to suffer the delays. |
… | |
… | |
469 | |
470 | |
470 | Example: fork a process and wait for it |
471 | Example: fork a process and wait for it |
471 | |
472 | |
472 | my $done = AnyEvent->condvar; |
473 | my $done = AnyEvent->condvar; |
473 | |
474 | |
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475 | # this forks and immediately calls exit in the child. this |
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476 | # normally has all sorts of bad consequences for your parent, |
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477 | # so take this as an example only. always fork and exec, |
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478 | # or call POSIX::_exit, in real code. |
474 | my $pid = fork or exit 5; |
479 | my $pid = fork or exit 5; |
475 | |
480 | |
476 | my $w = AnyEvent->child ( |
481 | my $w = AnyEvent->child ( |
477 | pid => $pid, |
482 | pid => $pid, |
478 | cb => sub { |
483 | cb => sub { |
… | |
… | |
718 | This works because for every event source (EOF on file handle), |
723 | This works because for every event source (EOF on file handle), |
719 | there is one call to "begin", so the condvar waits for all calls to |
724 | there is one call to "begin", so the condvar waits for all calls to |
720 | "end" before sending. |
725 | "end" before sending. |
721 | |
726 | |
722 | The ping example mentioned above is slightly more complicated, as |
727 | The ping example mentioned above is slightly more complicated, as |
723 | the there are results to be passwd back, and the number of tasks |
728 | the there are results to be passed back, and the number of tasks |
724 | that are begun can potentially be zero: |
729 | that are begun can potentially be zero: |
725 | |
730 | |
726 | my $cv = AnyEvent->condvar; |
731 | my $cv = AnyEvent->condvar; |
727 | |
732 | |
728 | my %result; |
733 | my %result; |
… | |
… | |
736 | }; |
741 | }; |
737 | } |
742 | } |
738 | |
743 | |
739 | $cv->end; |
744 | $cv->end; |
740 | |
745 | |
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746 | ... |
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747 | |
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748 | my $results = $cv->recv; |
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749 | |
741 | This code fragment supposedly pings a number of hosts and calls |
750 | This code fragment supposedly pings a number of hosts and calls |
742 | "send" after results for all then have have been gathered - in any |
751 | "send" after results for all then have have been gathered - in any |
743 | order. To achieve this, the code issues a call to "begin" when it |
752 | order. To achieve this, the code issues a call to "begin" when it |
744 | starts each ping request and calls "end" when it has received some |
753 | starts each ping request and calls "end" when it has received some |
745 | result for it. Since "begin" and "end" only maintain a counter, the |
754 | result for it. Since "begin" and "end" only maintain a counter, the |
… | |
… | |
774 | In list context, all parameters passed to "send" will be returned, |
783 | In list context, all parameters passed to "send" will be returned, |
775 | in scalar context only the first one will be returned. |
784 | in scalar context only the first one will be returned. |
776 | |
785 | |
777 | Note that doing a blocking wait in a callback is not supported by |
786 | Note that doing a blocking wait in a callback is not supported by |
778 | any event loop, that is, recursive invocation of a blocking "->recv" |
787 | any event loop, that is, recursive invocation of a blocking "->recv" |
779 | is not allowed, and the "recv" call will "croak" if such a condition |
788 | is not allowed and the "recv" call will "croak" if such a condition |
780 | is detected. This condition can be slightly loosened by using |
789 | is detected. This requirement can be dropped by relying on |
781 | Coro::AnyEvent, which allows you to do a blocking "->recv" from any |
790 | Coro::AnyEvent , which allows you to do a blocking "->recv" from any |
782 | thread that doesn't run the event loop itself. |
791 | thread that doesn't run the event loop itself. Coro::AnyEvent is |
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792 | loaded automatically when Coro is used with AnyEvent, so code does |
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793 | not need to do anything special to take advantage of that: any code |
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794 | that would normally block your program because it calls "recv", be |
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795 | executed in an "async" thread instead without blocking other |
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796 | threads. |
783 | |
797 | |
784 | Not all event models support a blocking wait - some die in that case |
798 | Not all event models support a blocking wait - some die in that case |
785 | (programs might want to do that to stay interactive), so *if you are |
799 | (programs might want to do that to stay interactive), so *if you are |
786 | using this from a module, never require a blocking wait*. Instead, |
800 | using this from a module, never require a blocking wait*. Instead, |
787 | let the caller decide whether the call will block or not (for |
801 | let the caller decide whether the call will block or not (for |
… | |
… | |
830 | by the main program. |
844 | by the main program. |
831 | |
845 | |
832 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
846 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
833 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
847 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
834 | AnyEvent::Impl::Tk based on Tk, very broken. |
848 | AnyEvent::Impl::Tk based on Tk, very broken. |
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|
849 | AnyEvent::Impl::UV based on UV, innovated square wheels. |
835 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
850 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
836 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
851 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
837 | AnyEvent::Impl::Irssi used when running within irssi. |
852 | AnyEvent::Impl::Irssi used when running within irssi. |
838 | AnyEvent::Impl::IOAsync based on IO::Async. |
853 | AnyEvent::Impl::IOAsync based on IO::Async. |
839 | AnyEvent::Impl::Cocoa based on Cocoa::EventLoop. |
854 | AnyEvent::Impl::Cocoa based on Cocoa::EventLoop. |
… | |
… | |
971 | To understand the usefulness of this function, consider a function |
986 | To understand the usefulness of this function, consider a function |
972 | that asynchronously does something for you and returns some |
987 | that asynchronously does something for you and returns some |
973 | transaction object or guard to let you cancel the operation. For |
988 | transaction object or guard to let you cancel the operation. For |
974 | example, "AnyEvent::Socket::tcp_connect": |
989 | example, "AnyEvent::Socket::tcp_connect": |
975 | |
990 | |
976 | # start a conenction attempt unless one is active |
991 | # start a connection attempt unless one is active |
977 | $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub { |
992 | $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub { |
978 | delete $self->{connect_guard}; |
993 | delete $self->{connect_guard}; |
979 | ... |
994 | ... |
980 | }; |
995 | }; |
981 | |
996 | |
… | |
… | |
1082 | modules come as part of AnyEvent, the others are available via CPAN (see |
1097 | 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 |
1098 | <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 |
1099 | non-exhaustive list), and the list is heavily biased towards modules of |
1085 | the AnyEvent author himself :) |
1100 | the AnyEvent author himself :) |
1086 | |
1101 | |
1087 | AnyEvent::Util |
1102 | AnyEvent::Util (part of the AnyEvent distribution) |
1088 | Contains various utility functions that replace often-used blocking |
1103 | Contains various utility functions that replace often-used blocking |
1089 | functions such as "inet_aton" with event/callback-based versions. |
1104 | functions such as "inet_aton" with event/callback-based versions. |
1090 | |
1105 | |
1091 | AnyEvent::Socket |
1106 | AnyEvent::Socket (part of the AnyEvent distribution) |
1092 | Provides various utility functions for (internet protocol) sockets, |
1107 | Provides various utility functions for (internet protocol) sockets, |
1093 | addresses and name resolution. Also functions to create non-blocking |
1108 | addresses and name resolution. Also functions to create non-blocking |
1094 | tcp connections or tcp servers, with IPv6 and SRV record support and |
1109 | tcp connections or tcp servers, with IPv6 and SRV record support and |
1095 | more. |
1110 | more. |
1096 | |
1111 | |
1097 | AnyEvent::Handle |
1112 | AnyEvent::Handle (part of the AnyEvent distribution) |
1098 | Provide read and write buffers, manages watchers for reads and |
1113 | Provide read and write buffers, manages watchers for reads and |
1099 | writes, supports raw and formatted I/O, I/O queued and fully |
1114 | writes, supports raw and formatted I/O, I/O queued and fully |
1100 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS). |
1115 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS). |
1101 | |
1116 | |
1102 | AnyEvent::DNS |
1117 | AnyEvent::DNS (part of the AnyEvent distribution) |
1103 | Provides rich asynchronous DNS resolver capabilities. |
1118 | Provides rich asynchronous DNS resolver capabilities. |
1104 | |
1119 | |
1105 | AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, |
1120 | AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, |
1106 | AnyEvent::IGS, AnyEvent::FCP |
1121 | AnyEvent::IGS, AnyEvent::FCP |
1107 | Implement event-based interfaces to the protocols of the same name |
1122 | Implement event-based interfaces to the protocols of the same name |
1108 | (for the curious, IGS is the International Go Server and FCP is the |
1123 | (for the curious, IGS is the International Go Server and FCP is the |
1109 | Freenet Client Protocol). |
1124 | Freenet Client Protocol). |
1110 | |
1125 | |
1111 | AnyEvent::AIO |
1126 | AnyEvent::AIO (part of the AnyEvent distribution) |
1112 | Truly asynchronous (as opposed to non-blocking) I/O, should be in |
1127 | Truly asynchronous (as opposed to non-blocking) I/O, should be in |
1113 | the toolbox of every event programmer. AnyEvent::AIO transparently |
1128 | the toolbox of every event programmer. AnyEvent::AIO transparently |
1114 | fuses IO::AIO and AnyEvent together, giving AnyEvent access to |
1129 | fuses IO::AIO and AnyEvent together, giving AnyEvent access to |
1115 | event-based file I/O, and much more. |
1130 | event-based file I/O, and much more. |
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|
1131 | |
|
|
1132 | AnyEvent::Fork, AnyEvent::Fork::RPC, AnyEvent::Fork::Pool, |
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1133 | AnyEvent::Fork::Remote |
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|
1134 | These let you safely fork new subprocesses, either locally or |
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1135 | remotely (e.g.v ia ssh), using some RPC protocol or not, without the |
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1136 | limitations normally imposed by fork (AnyEvent works fine for |
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1137 | example). Dynamically-resized worker pools are obviously included as |
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1138 | well. |
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1139 | |
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1140 | And they are quite tiny and fast as well - "abusing" AnyEvent::Fork |
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1141 | just to exec external programs can easily beat using "fork" and |
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1142 | "exec" (or even "system") in most programs. |
1116 | |
1143 | |
1117 | AnyEvent::Filesys::Notify |
1144 | AnyEvent::Filesys::Notify |
1118 | AnyEvent is good for non-blocking stuff, but it can't detect file or |
1145 | 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 |
1146 | path changes (e.g. "watch this directory for new files", "watch this |
1120 | file for changes"). The AnyEvent::Filesys::Notify module promises to |
1147 | file for changes"). The AnyEvent::Filesys::Notify module promises to |
… | |
… | |
1122 | and some weird, without doubt broken, stuff on OS X to monitor |
1149 | and some weird, without doubt broken, stuff on OS X to monitor |
1123 | files. It can fall back to blocking scans at regular intervals |
1150 | files. It can fall back to blocking scans at regular intervals |
1124 | transparently on other platforms, so it's about as portable as it |
1151 | transparently on other platforms, so it's about as portable as it |
1125 | gets. |
1152 | gets. |
1126 | |
1153 | |
1127 | (I haven't used it myself, but I haven't heard anybody complaining |
1154 | (I haven't used it myself, but it seems the biggest problem with it |
1128 | about it yet). |
1155 | is it quite bad performance). |
1129 | |
1156 | |
1130 | AnyEvent::DBI |
1157 | AnyEvent::DBI |
1131 | Executes DBI requests asynchronously in a proxy process for you, |
1158 | Executes DBI requests asynchronously in a proxy process for you, |
1132 | notifying you in an event-based way when the operation is finished. |
1159 | notifying you in an event-based way when the operation is finished. |
1133 | |
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|
1134 | AnyEvent::HTTPD |
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|
1135 | A simple embedded webserver. |
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|
1136 | |
1160 | |
1137 | AnyEvent::FastPing |
1161 | AnyEvent::FastPing |
1138 | The fastest ping in the west. |
1162 | The fastest ping in the west. |
1139 | |
1163 | |
1140 | Coro |
1164 | Coro |
… | |
… | |
1214 | This ensures that child processes will not see the "AE_" variables. |
1238 | This ensures that child processes will not see the "AE_" variables. |
1215 | |
1239 | |
1216 | The following environment variables are currently known to AnyEvent: |
1240 | The following environment variables are currently known to AnyEvent: |
1217 | |
1241 | |
1218 | "PERL_ANYEVENT_VERBOSE" |
1242 | "PERL_ANYEVENT_VERBOSE" |
1219 | By default, AnyEvent will only log messages with loglevel 3 |
1243 | By default, AnyEvent will log messages with loglevel 4 ("error") or |
1220 | ("critical") or higher (see AnyEvent::Log). You can set this |
1244 | higher (see AnyEvent::Log). You can set this environment variable to |
1221 | environment variable to a numerical loglevel to make AnyEvent more |
1245 | a numerical loglevel to make AnyEvent more (or less) talkative. |
1222 | (or less) talkative. |
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|
1223 | |
1246 | |
1224 | If you want to do more than just set the global logging level you |
1247 | If you want to do more than just set the global logging level you |
1225 | should have a look at "PERL_ANYEVENT_LOG", which allows much more |
1248 | should have a look at "PERL_ANYEVENT_LOG", which allows much more |
1226 | complex specifications. |
1249 | complex specifications. |
1227 | |
1250 | |
1228 | When set to 0 ("off"), then no messages whatsoever will be logged |
1251 | When set to 0 ("off"), then no messages whatsoever will be logged |
1229 | with the default logging settings. |
1252 | with everything else at defaults. |
1230 | |
1253 | |
1231 | When set to 5 or higher ("warn"), causes AnyEvent to warn about |
1254 | When set to 5 or higher ("warn"), AnyEvent warns about unexpected |
1232 | unexpected conditions, such as not being able to load the event |
1255 | conditions, such as not being able to load the event model specified |
1233 | model specified by "PERL_ANYEVENT_MODEL", or a guard callback |
1256 | by "PERL_ANYEVENT_MODEL", or a guard callback throwing an exception |
1234 | throwing an exception - this is the minimum recommended level. |
1257 | - this is the minimum recommended level for use during development. |
1235 | |
1258 | |
1236 | When set to 7 or higher (info), cause AnyEvent to report which event |
1259 | When set to 7 or higher (info), AnyEvent reports which event model |
1237 | model it chooses. |
1260 | it chooses. |
1238 | |
1261 | |
1239 | When set to 8 or higher (debug), then AnyEvent will report extra |
1262 | When set to 8 or higher (debug), then AnyEvent will report extra |
1240 | information on which optional modules it loads and how it implements |
1263 | information on which optional modules it loads and how it implements |
1241 | certain features. |
1264 | certain features. |
1242 | |
1265 | |
… | |
… | |
1254 | itself. |
1277 | itself. |
1255 | |
1278 | |
1256 | Note that specifying this environment variable causes the |
1279 | Note that specifying this environment variable causes the |
1257 | AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE" |
1280 | AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE" |
1258 | does not, so only using the latter saves a few hundred kB of memory |
1281 | does not, so only using the latter saves a few hundred kB of memory |
1259 | until the first message is being logged. |
1282 | unless a module explicitly needs the extra features of |
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|
1283 | AnyEvent::Log. |
1260 | |
1284 | |
1261 | "PERL_ANYEVENT_STRICT" |
1285 | "PERL_ANYEVENT_STRICT" |
1262 | AnyEvent does not do much argument checking by default, as thorough |
1286 | AnyEvent does not do much argument checking by default, as thorough |
1263 | argument checking is very costly. Setting this variable to a true |
1287 | argument checking is very costly. Setting this variable to a true |
1264 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1288 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
… | |
… | |
1317 | For example, to force the pure perl model (AnyEvent::Loop::Perl) you |
1341 | For example, to force the pure perl model (AnyEvent::Loop::Perl) you |
1318 | could start your program like this: |
1342 | could start your program like this: |
1319 | |
1343 | |
1320 | PERL_ANYEVENT_MODEL=Perl perl ... |
1344 | PERL_ANYEVENT_MODEL=Perl perl ... |
1321 | |
1345 | |
|
|
1346 | "PERL_ANYEVENT_IO_MODEL" |
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|
1347 | The current file I/O model - see AnyEvent::IO for more info. |
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|
1348 | |
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|
1349 | At the moment, only "Perl" (small, pure-perl, synchronous) and |
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|
1350 | "IOAIO" (truly asynchronous) are supported. The default is "IOAIO" |
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|
1351 | if AnyEvent::AIO can be loaded, otherwise it is "Perl". |
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|
1352 | |
1322 | "PERL_ANYEVENT_PROTOCOLS" |
1353 | "PERL_ANYEVENT_PROTOCOLS" |
1323 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
1354 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
1324 | preferences for IPv4 or IPv6. The default is unspecified (and might |
1355 | preferences for IPv4 or IPv6. The default is unspecified (and might |
1325 | change, or be the result of auto probing). |
1356 | change, or be the result of auto probing). |
1326 | |
1357 | |
… | |
… | |
1329 | mentioned will be used, and preference will be given to protocols |
1360 | mentioned will be used, and preference will be given to protocols |
1330 | mentioned earlier in the list. |
1361 | mentioned earlier in the list. |
1331 | |
1362 | |
1332 | This variable can effectively be used for denial-of-service attacks |
1363 | This variable can effectively be used for denial-of-service attacks |
1333 | against local programs (e.g. when setuid), although the impact is |
1364 | against local programs (e.g. when setuid), although the impact is |
1334 | likely small, as the program has to handle conenction and other |
1365 | likely small, as the program has to handle connection and other |
1335 | failures anyways. |
1366 | failures anyways. |
1336 | |
1367 | |
1337 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
1368 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
1338 | IPv6, but support both and try to use both. |
1369 | IPv6, but support both and try to use both. |
1339 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1370 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
… | |
… | |
1994 | This module is part of perl since release 5.008. It will be used |
2025 | This module is part of perl since release 5.008. It will be used |
1995 | when the chosen event library does not come with a timing source of |
2026 | when the chosen event library does not come with a timing source of |
1996 | its own. The pure-perl event loop (AnyEvent::Loop) will additionally |
2027 | its own. The pure-perl event loop (AnyEvent::Loop) will additionally |
1997 | load it to try to use a monotonic clock for timing stability. |
2028 | load it to try to use a monotonic clock for timing stability. |
1998 | |
2029 | |
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|
2030 | AnyEvent::AIO (and IO::AIO) |
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|
2031 | The default implementation of AnyEvent::IO is to do I/O |
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2032 | synchronously, stopping programs while they access the disk, which |
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2033 | is fine for a lot of programs. |
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2034 | |
|
|
2035 | Installing AnyEvent::AIO (and its IO::AIO dependency) makes it |
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2036 | switch to a true asynchronous implementation, so event processing |
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2037 | can continue even while waiting for disk I/O. |
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2038 | |
1999 | FORK |
2039 | FORK |
2000 | Most event libraries are not fork-safe. The ones who are usually are |
2040 | Most event libraries are not fork-safe. The ones who are usually are |
2001 | because they rely on inefficient but fork-safe "select" or "poll" calls |
2041 | because they rely on inefficient but fork-safe "select" or "poll" calls |
2002 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
2042 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
2003 | epoll are usually badly thought-out hacks that are incompatible with |
2043 | epoll are usually badly thought-out hacks that are incompatible with |
… | |
… | |
2010 | usually happens when the first AnyEvent watcher is created, or the |
2050 | usually happens when the first AnyEvent watcher is created, or the |
2011 | library is loaded). |
2051 | library is loaded). |
2012 | |
2052 | |
2013 | If you have to fork, you must either do so *before* creating your first |
2053 | If you have to fork, you must either do so *before* creating your first |
2014 | watcher OR you must not use AnyEvent at all in the child OR you must do |
2054 | watcher OR you must not use AnyEvent at all in the child OR you must do |
2015 | something completely out of the scope of AnyEvent. |
2055 | something completely out of the scope of AnyEvent (see below). |
2016 | |
2056 | |
2017 | The problem of doing event processing in the parent *and* the child is |
2057 | The problem of doing event processing in the parent *and* the child is |
2018 | much more complicated: even for backends that *are* fork-aware or |
2058 | much more complicated: even for backends that *are* fork-aware or |
2019 | fork-safe, their behaviour is not usually what you want: fork clones all |
2059 | fork-safe, their behaviour is not usually what you want: fork clones all |
2020 | watchers, that means all timers, I/O watchers etc. are active in both |
2060 | watchers, that means all timers, I/O watchers etc. are active in both |
2021 | parent and child, which is almost never what you want. USing "exec" to |
2061 | parent and child, which is almost never what you want. Using "exec" to |
2022 | start worker children from some kind of manage rprocess is usually |
2062 | start worker children from some kind of manage prrocess is usually |
2023 | preferred, because it is much easier and cleaner, at the expense of |
2063 | preferred, because it is much easier and cleaner, at the expense of |
2024 | having to have another binary. |
2064 | having to have another binary. |
|
|
2065 | |
|
|
2066 | In addition to logical problems with fork, there are also implementation |
|
|
2067 | problems. For example, on POSIX systems, you cannot fork at all in Perl |
|
|
2068 | code if a thread (I am talking of pthreads here) was ever created in the |
|
|
2069 | process, and this is just the tip of the iceberg. In general, using fork |
|
|
2070 | from Perl is difficult, and attempting to use fork without an exec to |
|
|
2071 | implement some kind of parallel processing is almost certainly doomed. |
|
|
2072 | |
|
|
2073 | To safely fork and exec, you should use a module such as Proc::FastSpawn |
|
|
2074 | that let's you safely fork and exec new processes. |
|
|
2075 | |
|
|
2076 | If you want to do multiprocessing using processes, you can look at the |
|
|
2077 | AnyEvent::Fork module (and some related modules such as |
|
|
2078 | AnyEvent::Fork::RPC, AnyEvent::Fork::Pool and AnyEvent::Fork::Remote). |
|
|
2079 | This module allows you to safely create subprocesses without any |
|
|
2080 | limitations - you can use X11 toolkits or AnyEvent in the children |
|
|
2081 | created by AnyEvent::Fork safely and without any special precautions. |
2025 | |
2082 | |
2026 | SECURITY CONSIDERATIONS |
2083 | SECURITY CONSIDERATIONS |
2027 | AnyEvent can be forced to load any event model via |
2084 | AnyEvent can be forced to load any event model via |
2028 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
2085 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
2029 | to execute arbitrary code or directly gain access, it can easily be used |
2086 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
2064 | |
2121 | |
2065 | Development/Debugging: AnyEvent::Strict (stricter checking), |
2122 | Development/Debugging: AnyEvent::Strict (stricter checking), |
2066 | AnyEvent::Debug (interactive shell, watcher tracing). |
2123 | AnyEvent::Debug (interactive shell, watcher tracing). |
2067 | |
2124 | |
2068 | Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event, |
2125 | Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event, |
2069 | Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK. |
2126 | Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK, Cocoa::EventLoop, UV. |
2070 | |
2127 | |
2071 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
2128 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
2072 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
2129 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
2073 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
2130 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
2074 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi, AnyEvent::Impl::FLTK. |
2131 | AnyEvent::Impl::IOAsync, AnyEvent::Impl::Irssi, AnyEvent::Impl::FLTK, |
|
|
2132 | AnyEvent::Impl::Cocoa, AnyEvent::Impl::UV. |
2075 | |
2133 | |
2076 | Non-blocking handles, pipes, stream sockets, TCP clients and servers: |
2134 | Non-blocking handles, pipes, stream sockets, TCP clients and servers: |
2077 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
2135 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
2078 | |
2136 | |
|
|
2137 | Asynchronous File I/O: AnyEvent::IO. |
|
|
2138 | |
2079 | Asynchronous DNS: AnyEvent::DNS. |
2139 | Asynchronous DNS: AnyEvent::DNS. |
2080 | |
2140 | |
2081 | Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. |
2141 | Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. |
2082 | |
2142 | |
2083 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, |
2143 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, |
2084 | AnyEvent::HTTP. |
2144 | AnyEvent::HTTP. |
2085 | |
2145 | |
2086 | AUTHOR |
2146 | AUTHOR |
2087 | Marc Lehmann <schmorp@schmorp.de> |
2147 | Marc Lehmann <schmorp@schmorp.de> |
2088 | http://home.schmorp.de/ |
2148 | http://anyevent.schmorp.de |
2089 | |
2149 | |