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Revision 1.156 by root, Fri Jun 6 10:23:50 2008 UTC vs.
Revision 1.168 by root, Tue Jul 8 23:53:37 2008 UTC

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
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
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
757=item L<AnyEvent::HTTP> 758=item L<AnyEvent::HTTP>
765 766
766=item L<AnyEvent::FastPing> 767=item L<AnyEvent::FastPing>
767 768
768The fastest ping in the west. 769The fastest ping in the west.
769 770
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>).
794
770=item L<Net::IRC3> 795=item L<Net::IRC3>
771 796
772AnyEvent based IRC client module family. 797AnyEvent based IRC client module family.
773 798
774=item L<Net::XMPP2> 799=item L<Net::XMPP2>
786 811
787=item L<Coro> 812=item L<Coro>
788 813
789Has special support for AnyEvent via L<Coro::AnyEvent>. 814Has special support for AnyEvent via L<Coro::AnyEvent>.
790 815
791=item L<AnyEvent::AIO>, L<IO::AIO>
792
793Truly asynchronous I/O, should be in the toolbox of every event
794programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
795together.
796
797=item L<AnyEvent::BDB>, L<BDB>
798
799Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
800IO::AIO and AnyEvent together.
801
802=item L<IO::Lambda> 816=item L<IO::Lambda>
803 817
804The 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.
805 819
806=back 820=back
812no warnings; 826no warnings;
813use strict; 827use strict;
814 828
815use Carp; 829use Carp;
816 830
817our $VERSION = 4.14; 831our $VERSION = 4.2;
818our $MODEL; 832our $MODEL;
819 833
820our $AUTOLOAD; 834our $AUTOLOAD;
821our @ISA; 835our @ISA;
822 836
925 $MODEL 939 $MODEL
926 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 940 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
927 } 941 }
928 } 942 }
929 943
944 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
945
930 unshift @ISA, $MODEL; 946 unshift @ISA, $MODEL;
931 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 947
948 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
932 949
933 (shift @post_detect)->() while @post_detect; 950 (shift @post_detect)->() while @post_detect;
934 } 951 }
935 952
936 $MODEL 953 $MODEL
984sub AnyEvent::Base::Signal::DESTROY { 1001sub AnyEvent::Base::Signal::DESTROY {
985 my ($signal, $cb) = @{$_[0]}; 1002 my ($signal, $cb) = @{$_[0]};
986 1003
987 delete $SIG_CB{$signal}{$cb}; 1004 delete $SIG_CB{$signal}{$cb};
988 1005
989 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; 1006 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
990} 1007}
991 1008
992# default implementation for ->child 1009# default implementation for ->child
993 1010
994our %PID_CB; 1011our %PID_CB;
1163conditions, such as not being able to load the event model specified by 1180conditions, such as not being able to load the event model specified by
1164C<PERL_ANYEVENT_MODEL>. 1181C<PERL_ANYEVENT_MODEL>.
1165 1182
1166When set to C<2> or higher, cause AnyEvent to report to STDERR which event 1183When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1167model it chooses. 1184model it chooses.
1185
1186=item C<PERL_ANYEVENT_STRICT>
1187
1188AnyEvent does not do much argument checking by default, as thorough
1189argument checking is very costly. Setting this variable to a true value
1190will cause AnyEvent to thoroughly check the arguments passed to most
1191method calls and croaks if it finds any problems. In other words, enables
1192"strict" mode. Unlike C<use strict> it is definitely recommended ot keep
1193it off in production.
1168 1194
1169=item C<PERL_ANYEVENT_MODEL> 1195=item C<PERL_ANYEVENT_MODEL>
1170 1196
1171This can be used to specify the event model to be used by AnyEvent, before 1197This can be used to specify the event model to be used by AnyEvent, before
1172auto detection and -probing kicks in. It must be a string consisting 1198auto detection and -probing kicks in. It must be a string consisting
1669 1695
1670 use AnyEvent; 1696 use AnyEvent;
1671 1697
1672Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1698Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1673be used to probe what backend is used and gain other information (which is 1699be used to probe what backend is used and gain other information (which is
1674probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1700probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1701$ENV{PERL_ANYEGENT_STRICT}.
1675 1702
1676 1703
1677=head1 BUGS 1704=head1 BUGS
1678 1705
1679Perl 5.8 has numerous memleaks that sometimes hit this module and are hard 1706Perl 5.8 has numerous memleaks that sometimes hit this module and are hard

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