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Revision 1.149 by root, Sat May 31 01:41:22 2008 UTC vs.
Revision 1.170 by root, Wed Jul 9 11:53:40 2008 UTC

1=head1 => NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6 6
33 33
34Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of 34Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35policy> and AnyEvent is I<small and efficient>. 35policy> and AnyEvent is I<small and efficient>.
36 36
37First and foremost, I<AnyEvent is not an event model> itself, it only 37First and foremost, I<AnyEvent is not an event model> itself, it only
38interfaces to whatever event model the main program happens to use in a 38interfaces to whatever event model the main program happens to use, in a
39pragmatic way. For event models and certain classes of immortals alike, 39pragmatic way. For event models and certain classes of immortals alike,
40the statement "there can only be one" is a bitter reality: In general, 40the statement "there can only be one" is a bitter reality: In general,
41only one event loop can be active at the same time in a process. AnyEvent 41only one event loop can be active at the same time in a process. AnyEvent
42helps hiding the differences between those event loops. 42cannot change this, but it can hide the differences between those event
43loops.
43 44
44The goal of AnyEvent is to offer module authors the ability to do event 45The goal of AnyEvent is to offer module authors the ability to do event
45programming (waiting for I/O or timer events) without subscribing to a 46programming (waiting for I/O or timer events) without subscribing to a
46religion, a way of living, and most importantly: without forcing your 47religion, a way of living, and most importantly: without forcing your
47module users into the same thing by forcing them to use the same event 48module users into the same thing by forcing them to use the same event
48model you use. 49model you use.
49 50
50For modules like POE or IO::Async (which is a total misnomer as it is 51For modules like POE or IO::Async (which is a total misnomer as it is
51actually doing all I/O I<synchronously>...), using them in your module is 52actually doing all I/O I<synchronously>...), using them in your module is
52like joining a cult: After you joined, you are dependent on them and you 53like joining a cult: After you joined, you are dependent on them and you
53cannot use anything else, as it is simply incompatible to everything that 54cannot use anything else, as they are simply incompatible to everything
54isn't itself. What's worse, all the potential users of your module are 55that isn't them. What's worse, all the potential users of your
55I<also> forced to use the same event loop you use. 56module are I<also> forced to use the same event loop you use.
56 57
57AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 58AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58fine. AnyEvent + Tk works fine etc. etc. but none of these work together 59fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if 60with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
60your module uses one of those, every user of your module has to use it, 61your module uses one of those, every user of your module has to use it,
61too. But if your module uses AnyEvent, it works transparently with all 62too. But if your module uses AnyEvent, it works transparently with all
62event models it supports (including stuff like POE and IO::Async, as long 63event models it supports (including stuff like IO::Async, as long as those
63as those use one of the supported event loops. It is trivial to add new 64use one of the supported event loops. It is trivial to add new event loops
64event loops to AnyEvent, too, so it is future-proof). 65to AnyEvent, too, so it is future-proof).
65 66
66In addition to being free of having to use I<the one and only true event 67In addition to being free of having to use I<the one and only true event
67model>, AnyEvent also is free of bloat and policy: with POE or similar 68model>, AnyEvent also is free of bloat and policy: with POE or similar
68modules, you get an enormous amount of code and strict rules you have to 69modules, you get an enormous amount of code and strict rules you have to
69follow. AnyEvent, on the other hand, is lean and up to the point, by only 70follow. AnyEvent, on the other hand, is lean and up to the point, by only
138Many watchers either are used with "recursion" (repeating timers for 139Many watchers either are used with "recursion" (repeating timers for
139example), or need to refer to their watcher object in other ways. 140example), or need to refer to their watcher object in other ways.
140 141
141An any way to achieve that is this pattern: 142An any way to achieve that is this pattern:
142 143
143 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 144 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
144 # you can use $w here, for example to undef it 145 # you can use $w here, for example to undef it
145 undef $w; 146 undef $w;
146 }); 147 });
147 148
148Note that C<my $w; $w => combination. This is necessary because in Perl, 149Note that C<my $w; $w => combination. This is necessary because in Perl,
149my variables are only visible after the statement in which they are 150my variables are only visible after the statement in which they are
150declared. 151declared.
151 152
152=head2 I/O WATCHERS 153=head2 I/O WATCHERS
153 154
154You can create an I/O watcher by calling the C<< AnyEvent->io >> method 155You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155with the following mandatory key-value pairs as arguments: 156with the following mandatory key-value pairs as arguments:
156 157
157C<fh> the Perl I<file handle> (I<not> file descriptor) to watch 158C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
158for events. C<poll> must be a string that is either C<r> or C<w>, 159(AnyEvent might or might not keep a reference to this file handle). C<poll>
159which creates a watcher waiting for "r"eadable or "w"ritable events, 160must be a string that is either C<r> or C<w>, which creates a watcher
160respectively. C<cb> is the callback to invoke each time the file handle 161waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
161becomes ready. 162callback to invoke each time the file handle becomes ready.
162 163
163Although the callback might get passed parameters, their value and 164Although the callback might get passed parameters, their value and
164presence is undefined and you cannot rely on them. Portable AnyEvent 165presence is undefined and you cannot rely on them. Portable AnyEvent
165callbacks cannot use arguments passed to I/O watcher callbacks. 166callbacks cannot use arguments passed to I/O watcher callbacks.
166 167
170 171
171Some event loops issue spurious readyness notifications, so you should 172Some event loops issue spurious readyness notifications, so you should
172always use non-blocking calls when reading/writing from/to your file 173always use non-blocking calls when reading/writing from/to your file
173handles. 174handles.
174 175
175Example:
176
177 # wait for readability of STDIN, then read a line and disable the watcher 176Example: wait for readability of STDIN, then read a line and disable the
177watcher.
178
178 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 179 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
179 chomp (my $input = <STDIN>); 180 chomp (my $input = <STDIN>);
180 warn "read: $input\n"; 181 warn "read: $input\n";
181 undef $w; 182 undef $w;
182 }); 183 });
192 193
193Although the callback might get passed parameters, their value and 194Although the callback might get passed parameters, their value and
194presence is undefined and you cannot rely on them. Portable AnyEvent 195presence is undefined and you cannot rely on them. Portable AnyEvent
195callbacks cannot use arguments passed to time watcher callbacks. 196callbacks cannot use arguments passed to time watcher callbacks.
196 197
197The timer callback will be invoked at most once: if you want a repeating 198The callback will normally be invoked once only. If you specify another
198timer you have to create a new watcher (this is a limitation by both Tk 199parameter, C<interval>, as a strictly positive number (> 0), then the
199and Glib). 200callback will be invoked regularly at that interval (in fractional
201seconds) after the first invocation. If C<interval> is specified with a
202false value, then it is treated as if it were missing.
200 203
201Example: 204The callback will be rescheduled before invoking the callback, but no
205attempt is done to avoid timer drift in most backends, so the interval is
206only approximate.
202 207
203 # fire an event after 7.7 seconds 208Example: fire an event after 7.7 seconds.
209
204 my $w = AnyEvent->timer (after => 7.7, cb => sub { 210 my $w = AnyEvent->timer (after => 7.7, cb => sub {
205 warn "timeout\n"; 211 warn "timeout\n";
206 }); 212 });
207 213
208 # to cancel the timer: 214 # to cancel the timer:
209 undef $w; 215 undef $w;
210 216
211Example 2:
212
213 # fire an event after 0.5 seconds, then roughly every second 217Example 2: fire an event after 0.5 seconds, then roughly every second.
214 my $w;
215 218
216 my $cb = sub {
217 # cancel the old timer while creating a new one
218 $w = AnyEvent->timer (after => 1, cb => $cb); 219 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
220 warn "timeout\n";
219 }; 221 };
220
221 # start the "loop" by creating the first watcher
222 $w = AnyEvent->timer (after => 0.5, cb => $cb);
223 222
224=head3 TIMING ISSUES 223=head3 TIMING ISSUES
225 224
226There are two ways to handle timers: based on real time (relative, "fire 225There are two ways to handle timers: based on real time (relative, "fire
227in 10 seconds") and based on wallclock time (absolute, "fire at 12 226in 10 seconds") and based on wallclock time (absolute, "fire at 12
305=back 304=back
306 305
307=head2 SIGNAL WATCHERS 306=head2 SIGNAL WATCHERS
308 307
309You can watch for signals using a signal watcher, C<signal> is the signal 308You can watch for signals using a signal watcher, C<signal> is the signal
310I<name> without any C<SIG> prefix, C<cb> is the Perl callback to 309I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
311be invoked whenever a signal occurs. 310callback to be invoked whenever a signal occurs.
312 311
313Although the callback might get passed parameters, their value and 312Although the callback might get passed parameters, their value and
314presence is undefined and you cannot rely on them. Portable AnyEvent 313presence is undefined and you cannot rely on them. Portable AnyEvent
315callbacks cannot use arguments passed to signal watcher callbacks. 314callbacks cannot use arguments passed to signal watcher callbacks.
316 315
352AnyEvent program, you I<have> to create at least one watcher before you 351AnyEvent program, you I<have> to create at least one watcher before you
353C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 352C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
354 353
355Example: fork a process and wait for it 354Example: fork a process and wait for it
356 355
357 my $done = AnyEvent->condvar; 356 my $done = AnyEvent->condvar;
358 357
359 my $pid = fork or exit 5; 358 my $pid = fork or exit 5;
360 359
361 my $w = AnyEvent->child ( 360 my $w = AnyEvent->child (
362 pid => $pid, 361 pid => $pid,
363 cb => sub { 362 cb => sub {
364 my ($pid, $status) = @_; 363 my ($pid, $status) = @_;
365 warn "pid $pid exited with status $status"; 364 warn "pid $pid exited with status $status";
366 $done->send; 365 $done->send;
367 }, 366 },
368 ); 367 );
369 368
370 # do something else, then wait for process exit 369 # do something else, then wait for process exit
371 $done->recv; 370 $done->recv;
372 371
373=head2 CONDITION VARIABLES 372=head2 CONDITION VARIABLES
374 373
375If you are familiar with some event loops you will know that all of them 374If you are familiar with some event loops you will know that all of them
376require you to run some blocking "loop", "run" or similar function that 375require you to run some blocking "loop", "run" or similar function that
738=item L<AnyEvent::Util> 737=item L<AnyEvent::Util>
739 738
740Contains various utility functions that replace often-used but blocking 739Contains various utility functions that replace often-used but blocking
741functions such as C<inet_aton> by event-/callback-based versions. 740functions such as C<inet_aton> by event-/callback-based versions.
742 741
743=item L<AnyEvent::Handle>
744
745Provide read and write buffers and manages watchers for reads and writes.
746
747=item L<AnyEvent::Socket> 742=item L<AnyEvent::Socket>
748 743
749Provides various utility functions for (internet protocol) sockets, 744Provides various utility functions for (internet protocol) sockets,
750addresses and name resolution. Also functions to create non-blocking tcp 745addresses and name resolution. Also functions to create non-blocking tcp
751connections or tcp servers, with IPv6 and SRV record support and more. 746connections or tcp servers, with IPv6 and SRV record support and more.
752 747
748=item L<AnyEvent::Handle>
749
750Provide read and write buffers, manages watchers for reads and writes,
751supports raw and formatted I/O, I/O queued and fully transparent and
752non-blocking SSL/TLS.
753
753=item L<AnyEvent::DNS> 754=item L<AnyEvent::DNS>
754 755
755Provides rich asynchronous DNS resolver capabilities. 756Provides rich asynchronous DNS resolver capabilities.
756 757
758=item L<AnyEvent::HTTP>
759
760A simple-to-use HTTP library that is capable of making a lot of concurrent
761HTTP requests.
762
757=item L<AnyEvent::HTTPD> 763=item L<AnyEvent::HTTPD>
758 764
759Provides a simple web application server framework. 765Provides a simple web application server framework.
760 766
761=item L<AnyEvent::FastPing> 767=item L<AnyEvent::FastPing>
762 768
763The fastest ping in the west. 769The fastest ping in the west.
770
771=item L<AnyEvent::DBI>
772
773Executes L<DBI> requests asynchronously in a proxy process.
774
775=item L<AnyEvent::AIO>
776
777Truly asynchronous I/O, should be in the toolbox of every event
778programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
779together.
780
781=item L<AnyEvent::BDB>
782
783Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
784L<BDB> and AnyEvent together.
785
786=item L<AnyEvent::GPSD>
787
788A non-blocking interface to gpsd, a daemon delivering GPS information.
789
790=item L<AnyEvent::IGS>
791
792A non-blocking interface to the Internet Go Server protocol (used by
793L<App::IGS>).
764 794
765=item L<Net::IRC3> 795=item L<Net::IRC3>
766 796
767AnyEvent based IRC client module family. 797AnyEvent based IRC client module family.
768 798
781 811
782=item L<Coro> 812=item L<Coro>
783 813
784Has special support for AnyEvent via L<Coro::AnyEvent>. 814Has special support for AnyEvent via L<Coro::AnyEvent>.
785 815
786=item L<AnyEvent::AIO>, L<IO::AIO>
787
788Truly asynchronous I/O, should be in the toolbox of every event
789programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
790together.
791
792=item L<AnyEvent::BDB>, L<BDB>
793
794Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
795IO::AIO and AnyEvent together.
796
797=item L<IO::Lambda> 816=item L<IO::Lambda>
798 817
799The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 818The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
800 819
801=back 820=back
807no warnings; 826no warnings;
808use strict; 827use strict;
809 828
810use Carp; 829use Carp;
811 830
812our $VERSION = 4.11; 831our $VERSION = 4.2;
813our $MODEL; 832our $MODEL;
814 833
815our $AUTOLOAD; 834our $AUTOLOAD;
816our @ISA; 835our @ISA;
817 836
920 $MODEL 939 $MODEL
921 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 940 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
922 } 941 }
923 } 942 }
924 943
944 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
945
925 unshift @ISA, $MODEL; 946 unshift @ISA, $MODEL;
926 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 947
948 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
927 949
928 (shift @post_detect)->() while @post_detect; 950 (shift @post_detect)->() while @post_detect;
929 } 951 }
930 952
931 $MODEL 953 $MODEL
939 961
940 detect unless $MODEL; 962 detect unless $MODEL;
941 963
942 my $class = shift; 964 my $class = shift;
943 $class->$func (@_); 965 $class->$func (@_);
966}
967
968# utility function to dup a filehandle. this is used by many backends
969# to support binding more than one watcher per filehandle (they usually
970# allow only one watcher per fd, so we dup it to get a different one).
971sub _dupfh($$$$) {
972 my ($poll, $fh, $r, $w) = @_;
973
974 require Fcntl;
975
976 # cygwin requires the fh mode to be matching, unix doesn't
977 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
978 : $poll eq "w" ? ($w, ">")
979 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
980
981 open my $fh2, "$mode&" . fileno $fh
982 or die "cannot dup() filehandle: $!";
983
984 # we assume CLOEXEC is already set by perl in all important cases
985
986 ($fh2, $rw)
944} 987}
945 988
946package AnyEvent::Base; 989package AnyEvent::Base;
947 990
948# default implementation for now and time 991# default implementation for now and time
979sub AnyEvent::Base::Signal::DESTROY { 1022sub AnyEvent::Base::Signal::DESTROY {
980 my ($signal, $cb) = @{$_[0]}; 1023 my ($signal, $cb) = @{$_[0]};
981 1024
982 delete $SIG_CB{$signal}{$cb}; 1025 delete $SIG_CB{$signal}{$cb};
983 1026
984 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; 1027 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
985} 1028}
986 1029
987# default implementation for ->child 1030# default implementation for ->child
988 1031
989our %PID_CB; 1032our %PID_CB;
1159C<PERL_ANYEVENT_MODEL>. 1202C<PERL_ANYEVENT_MODEL>.
1160 1203
1161When set to C<2> or higher, cause AnyEvent to report to STDERR which event 1204When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1162model it chooses. 1205model it chooses.
1163 1206
1207=item C<PERL_ANYEVENT_STRICT>
1208
1209AnyEvent does not do much argument checking by default, as thorough
1210argument checking is very costly. Setting this variable to a true value
1211will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1212check the arguments passed to most method calls. If it finds any problems
1213it will croak.
1214
1215In other words, enables "strict" mode.
1216
1217Unlike C<use strict> it is definitely recommended ot keep it off in
1218production.
1219
1164=item C<PERL_ANYEVENT_MODEL> 1220=item C<PERL_ANYEVENT_MODEL>
1165 1221
1166This can be used to specify the event model to be used by AnyEvent, before 1222This can be used to specify the event model to be used by AnyEvent, before
1167auto detection and -probing kicks in. It must be a string consisting 1223auto detection and -probing kicks in. It must be a string consisting
1168entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1224entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1173This functionality might change in future versions. 1229This functionality might change in future versions.
1174 1230
1175For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1231For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1176could start your program like this: 1232could start your program like this:
1177 1233
1178 PERL_ANYEVENT_MODEL=Perl perl ... 1234 PERL_ANYEVENT_MODEL=Perl perl ...
1179 1235
1180=item C<PERL_ANYEVENT_PROTOCOLS> 1236=item C<PERL_ANYEVENT_PROTOCOLS>
1181 1237
1182Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences 1238Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1183for IPv4 or IPv6. The default is unspecified (and might change, or be the result 1239for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1658specified in the variable. 1714specified in the variable.
1659 1715
1660You can make AnyEvent completely ignore this variable by deleting it 1716You can make AnyEvent completely ignore this variable by deleting it
1661before the first watcher gets created, e.g. with a C<BEGIN> block: 1717before the first watcher gets created, e.g. with a C<BEGIN> block:
1662 1718
1663 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1719 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1664 1720
1665 use AnyEvent; 1721 use AnyEvent;
1666 1722
1667Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1723Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1668be used to probe what backend is used and gain other information (which is 1724be used to probe what backend is used and gain other information (which is
1669probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1725probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1726$ENV{PERL_ANYEGENT_STRICT}.
1727
1728
1729=head1 BUGS
1730
1731Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1732to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1733and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1734mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
1735pronounced).
1670 1736
1671 1737
1672=head1 SEE ALSO 1738=head1 SEE ALSO
1673 1739
1674Utility functions: L<AnyEvent::Util>. 1740Utility functions: L<AnyEvent::Util>.
1691Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. 1757Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1692 1758
1693 1759
1694=head1 AUTHOR 1760=head1 AUTHOR
1695 1761
1696 Marc Lehmann <schmorp@schmorp.de> 1762 Marc Lehmann <schmorp@schmorp.de>
1697 http://home.schmorp.de/ 1763 http://home.schmorp.de/
1698 1764
1699=cut 1765=cut
1700 1766
17011 17671
1702 1768

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