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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
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
11 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { 11 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });
12 ...
13 });
14 12
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 13 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
15
16 print AnyEvent->now; # prints current event loop time
17 print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18
19 my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20
21 my $w = AnyEvent->child (pid => $pid, cb => sub {
22 my ($pid, $status) = @_;
16 ... 23 ...
17 }); 24 });
18 25
19 my $w = AnyEvent->condvar; # stores whether a condition was flagged 26 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->send; # wake up current and all future recv's 27 $w->send; # wake up current and all future recv's
21 $w->recv; # enters "main loop" till $condvar gets ->send 28 $w->recv; # enters "main loop" till $condvar gets ->send
29 # use a condvar in callback mode:
30 $w->cb (sub { $_[0]->recv });
31
32=head1 INTRODUCTION/TUTORIAL
33
34This manpage is mainly a reference manual. If you are interested
35in a tutorial or some gentle introduction, have a look at the
36L<AnyEvent::Intro> manpage.
22 37
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 38=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 39
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 40Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent? 41nowadays. So what is different about AnyEvent?
27 42
28Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of 43Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29policy> and AnyEvent is I<small and efficient>. 44policy> and AnyEvent is I<small and efficient>.
30 45
31First and foremost, I<AnyEvent is not an event model> itself, it only 46First and foremost, I<AnyEvent is not an event model> itself, it only
32interfaces to whatever event model the main program happens to use in a 47interfaces to whatever event model the main program happens to use, in a
33pragmatic way. For event models and certain classes of immortals alike, 48pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality: In general, 49the statement "there can only be one" is a bitter reality: In general,
35only one event loop can be active at the same time in a process. AnyEvent 50only one event loop can be active at the same time in a process. AnyEvent
36helps hiding the differences between those event loops. 51cannot change this, but it can hide the differences between those event
52loops.
37 53
38The goal of AnyEvent is to offer module authors the ability to do event 54The goal of AnyEvent is to offer module authors the ability to do event
39programming (waiting for I/O or timer events) without subscribing to a 55programming (waiting for I/O or timer events) without subscribing to a
40religion, a way of living, and most importantly: without forcing your 56religion, a way of living, and most importantly: without forcing your
41module users into the same thing by forcing them to use the same event 57module users into the same thing by forcing them to use the same event
42model you use. 58model you use.
43 59
44For modules like POE or IO::Async (which is a total misnomer as it is 60For modules like POE or IO::Async (which is a total misnomer as it is
45actually doing all I/O I<synchronously>...), using them in your module is 61actually doing all I/O I<synchronously>...), using them in your module is
46like joining a cult: After you joined, you are dependent on them and you 62like joining a cult: After you joined, you are dependent on them and you
47cannot use anything else, as it is simply incompatible to everything that 63cannot use anything else, as they are simply incompatible to everything
48isn't itself. What's worse, all the potential users of your module are 64that isn't them. What's worse, all the potential users of your
49I<also> forced to use the same event loop you use. 65module are I<also> forced to use the same event loop you use.
50 66
51AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 67AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52fine. AnyEvent + Tk works fine etc. etc. but none of these work together 68fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if 69with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54your module uses one of those, every user of your module has to use it, 70your module uses one of those, every user of your module has to use it,
55too. But if your module uses AnyEvent, it works transparently with all 71too. But if your module uses AnyEvent, it works transparently with all
56event models it supports (including stuff like POE and IO::Async, as long 72event models it supports (including stuff like IO::Async, as long as those
57as those use one of the supported event loops. It is trivial to add new 73use one of the supported event loops. It is trivial to add new event loops
58event loops to AnyEvent, too, so it is future-proof). 74to AnyEvent, too, so it is future-proof).
59 75
60In addition to being free of having to use I<the one and only true event 76In addition to being free of having to use I<the one and only true event
61model>, AnyEvent also is free of bloat and policy: with POE or similar 77model>, AnyEvent also is free of bloat and policy: with POE or similar
62modules, you get an enormous amount of code and strict rules you have to 78modules, you get an enormous amount of code and strict rules you have to
63follow. AnyEvent, on the other hand, is lean and up to the point, by only 79follow. AnyEvent, on the other hand, is lean and up to the point, by only
64offering the functionality that is necessary, in as thin as a wrapper as 80offering the functionality that is necessary, in as thin as a wrapper as
65technically possible. 81technically possible.
66 82
83Of course, AnyEvent comes with a big (and fully optional!) toolbox
84of useful functionality, such as an asynchronous DNS resolver, 100%
85non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
86such as Windows) and lots of real-world knowledge and workarounds for
87platform bugs and differences.
88
67Of course, if you want lots of policy (this can arguably be somewhat 89Now, if you I<do want> lots of policy (this can arguably be somewhat
68useful) and you want to force your users to use the one and only event 90useful) and you want to force your users to use the one and only event
69model, you should I<not> use this module. 91model, you should I<not> use this module.
70 92
71=head1 DESCRIPTION 93=head1 DESCRIPTION
72 94
102starts using it, all bets are off. Maybe you should tell their authors to 124starts using it, all bets are off. Maybe you should tell their authors to
103use AnyEvent so their modules work together with others seamlessly... 125use AnyEvent so their modules work together with others seamlessly...
104 126
105The pure-perl implementation of AnyEvent is called 127The pure-perl implementation of AnyEvent is called
106C<AnyEvent::Impl::Perl>. Like other event modules you can load it 128C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107explicitly. 129explicitly and enjoy the high availability of that event loop :)
108 130
109=head1 WATCHERS 131=head1 WATCHERS
110 132
111AnyEvent has the central concept of a I<watcher>, which is an object that 133AnyEvent has the central concept of a I<watcher>, which is an object that
112stores relevant data for each kind of event you are waiting for, such as 134stores relevant data for each kind of event you are waiting for, such as
126Many watchers either are used with "recursion" (repeating timers for 148Many watchers either are used with "recursion" (repeating timers for
127example), or need to refer to their watcher object in other ways. 149example), or need to refer to their watcher object in other ways.
128 150
129An any way to achieve that is this pattern: 151An any way to achieve that is this pattern:
130 152
131 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 153 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132 # you can use $w here, for example to undef it 154 # you can use $w here, for example to undef it
133 undef $w; 155 undef $w;
134 }); 156 });
135 157
136Note that C<my $w; $w => combination. This is necessary because in Perl, 158Note that C<my $w; $w => combination. This is necessary because in Perl,
137my variables are only visible after the statement in which they are 159my variables are only visible after the statement in which they are
138declared. 160declared.
139 161
140=head2 I/O WATCHERS 162=head2 I/O WATCHERS
141 163
142You can create an I/O watcher by calling the C<< AnyEvent->io >> method 164You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143with the following mandatory key-value pairs as arguments: 165with the following mandatory key-value pairs as arguments:
144 166
145C<fh> the Perl I<file handle> (I<not> file descriptor) to watch 167C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
146for events. C<poll> must be a string that is either C<r> or C<w>, 168(AnyEvent might or might not keep a reference to this file handle). C<poll>
147which creates a watcher waiting for "r"eadable or "w"ritable events, 169must be a string that is either C<r> or C<w>, which creates a watcher
148respectively. C<cb> is the callback to invoke each time the file handle 170waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
149becomes ready. 171callback to invoke each time the file handle becomes ready.
150 172
151Although the callback might get passed parameters, their value and 173Although the callback might get passed parameters, their value and
152presence is undefined and you cannot rely on them. Portable AnyEvent 174presence is undefined and you cannot rely on them. Portable AnyEvent
153callbacks cannot use arguments passed to I/O watcher callbacks. 175callbacks cannot use arguments passed to I/O watcher callbacks.
154 176
158 180
159Some event loops issue spurious readyness notifications, so you should 181Some event loops issue spurious readyness notifications, so you should
160always use non-blocking calls when reading/writing from/to your file 182always use non-blocking calls when reading/writing from/to your file
161handles. 183handles.
162 184
163Example:
164
165 # wait for readability of STDIN, then read a line and disable the watcher 185Example: wait for readability of STDIN, then read a line and disable the
186watcher.
187
166 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 188 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167 chomp (my $input = <STDIN>); 189 chomp (my $input = <STDIN>);
168 warn "read: $input\n"; 190 warn "read: $input\n";
169 undef $w; 191 undef $w;
170 }); 192 });
180 202
181Although the callback might get passed parameters, their value and 203Although the callback might get passed parameters, their value and
182presence is undefined and you cannot rely on them. Portable AnyEvent 204presence is undefined and you cannot rely on them. Portable AnyEvent
183callbacks cannot use arguments passed to time watcher callbacks. 205callbacks cannot use arguments passed to time watcher callbacks.
184 206
185The timer callback will be invoked at most once: if you want a repeating 207The callback will normally be invoked once only. If you specify another
186timer you have to create a new watcher (this is a limitation by both Tk 208parameter, C<interval>, as a strictly positive number (> 0), then the
187and Glib). 209callback will be invoked regularly at that interval (in fractional
210seconds) after the first invocation. If C<interval> is specified with a
211false value, then it is treated as if it were missing.
188 212
189Example: 213The callback will be rescheduled before invoking the callback, but no
214attempt is done to avoid timer drift in most backends, so the interval is
215only approximate.
190 216
191 # fire an event after 7.7 seconds 217Example: fire an event after 7.7 seconds.
218
192 my $w = AnyEvent->timer (after => 7.7, cb => sub { 219 my $w = AnyEvent->timer (after => 7.7, cb => sub {
193 warn "timeout\n"; 220 warn "timeout\n";
194 }); 221 });
195 222
196 # to cancel the timer: 223 # to cancel the timer:
197 undef $w; 224 undef $w;
198 225
199Example 2:
200
201 # fire an event after 0.5 seconds, then roughly every second 226Example 2: fire an event after 0.5 seconds, then roughly every second.
202 my $w;
203 227
204 my $cb = sub {
205 # cancel the old timer while creating a new one
206 $w = AnyEvent->timer (after => 1, cb => $cb); 228 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
229 warn "timeout\n";
207 }; 230 };
208
209 # start the "loop" by creating the first watcher
210 $w = AnyEvent->timer (after => 0.5, cb => $cb);
211 231
212=head3 TIMING ISSUES 232=head3 TIMING ISSUES
213 233
214There are two ways to handle timers: based on real time (relative, "fire 234There are two ways to handle timers: based on real time (relative, "fire
215in 10 seconds") and based on wallclock time (absolute, "fire at 12 235in 10 seconds") and based on wallclock time (absolute, "fire at 12
227timers. 247timers.
228 248
229AnyEvent always prefers relative timers, if available, matching the 249AnyEvent always prefers relative timers, if available, matching the
230AnyEvent API. 250AnyEvent API.
231 251
252AnyEvent has two additional methods that return the "current time":
253
254=over 4
255
256=item AnyEvent->time
257
258This returns the "current wallclock time" as a fractional number of
259seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
260return, and the result is guaranteed to be compatible with those).
261
262It progresses independently of any event loop processing, i.e. each call
263will check the system clock, which usually gets updated frequently.
264
265=item AnyEvent->now
266
267This also returns the "current wallclock time", but unlike C<time>, above,
268this value might change only once per event loop iteration, depending on
269the event loop (most return the same time as C<time>, above). This is the
270time that AnyEvent's timers get scheduled against.
271
272I<In almost all cases (in all cases if you don't care), this is the
273function to call when you want to know the current time.>
274
275This function is also often faster then C<< AnyEvent->time >>, and
276thus the preferred method if you want some timestamp (for example,
277L<AnyEvent::Handle> uses this to update it's activity timeouts).
278
279The rest of this section is only of relevance if you try to be very exact
280with your timing, you can skip it without bad conscience.
281
282For a practical example of when these times differ, consider L<Event::Lib>
283and L<EV> and the following set-up:
284
285The event loop is running and has just invoked one of your callback at
286time=500 (assume no other callbacks delay processing). In your callback,
287you wait a second by executing C<sleep 1> (blocking the process for a
288second) and then (at time=501) you create a relative timer that fires
289after three seconds.
290
291With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
292both return C<501>, because that is the current time, and the timer will
293be scheduled to fire at time=504 (C<501> + C<3>).
294
295With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
296time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
297last event processing phase started. With L<EV>, your timer gets scheduled
298to run at time=503 (C<500> + C<3>).
299
300In one sense, L<Event::Lib> is more exact, as it uses the current time
301regardless of any delays introduced by event processing. However, most
302callbacks do not expect large delays in processing, so this causes a
303higher drift (and a lot more system calls to get the current time).
304
305In another sense, L<EV> is more exact, as your timer will be scheduled at
306the same time, regardless of how long event processing actually took.
307
308In either case, if you care (and in most cases, you don't), then you
309can get whatever behaviour you want with any event loop, by taking the
310difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311account.
312
313=back
314
232=head2 SIGNAL WATCHERS 315=head2 SIGNAL WATCHERS
233 316
234You can watch for signals using a signal watcher, C<signal> is the signal 317You can watch for signals using a signal watcher, C<signal> is the signal
235I<name> without any C<SIG> prefix, C<cb> is the Perl callback to 318I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236be invoked whenever a signal occurs. 319callback to be invoked whenever a signal occurs.
237 320
238Although the callback might get passed parameters, their value and 321Although the callback might get passed parameters, their value and
239presence is undefined and you cannot rely on them. Portable AnyEvent 322presence is undefined and you cannot rely on them. Portable AnyEvent
240callbacks cannot use arguments passed to signal watcher callbacks. 323callbacks cannot use arguments passed to signal watcher callbacks.
241 324
257=head2 CHILD PROCESS WATCHERS 340=head2 CHILD PROCESS WATCHERS
258 341
259You can also watch on a child process exit and catch its exit status. 342You can also watch on a child process exit and catch its exit status.
260 343
261The child process is specified by the C<pid> argument (if set to C<0>, it 344The child process is specified by the C<pid> argument (if set to C<0>, it
262watches for any child process exit). The watcher will trigger as often 345watches for any child process exit). The watcher will triggered only when
263as status change for the child are received. This works by installing a 346the child process has finished and an exit status is available, not on
264signal handler for C<SIGCHLD>. The callback will be called with the pid 347any trace events (stopped/continued).
265and exit status (as returned by waitpid), so unlike other watcher types, 348
266you I<can> rely on child watcher callback arguments. 349The callback will be called with the pid and exit status (as returned by
350waitpid), so unlike other watcher types, you I<can> rely on child watcher
351callback arguments.
352
353This watcher type works by installing a signal handler for C<SIGCHLD>,
354and since it cannot be shared, nothing else should use SIGCHLD or reap
355random child processes (waiting for specific child processes, e.g. inside
356C<system>, is just fine).
267 357
268There is a slight catch to child watchers, however: you usually start them 358There is a slight catch to child watchers, however: you usually start them
269I<after> the child process was created, and this means the process could 359I<after> the child process was created, and this means the process could
270have exited already (and no SIGCHLD will be sent anymore). 360have exited already (and no SIGCHLD will be sent anymore).
271 361
277AnyEvent program, you I<have> to create at least one watcher before you 367AnyEvent program, you I<have> to create at least one watcher before you
278C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 368C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279 369
280Example: fork a process and wait for it 370Example: fork a process and wait for it
281 371
282 my $done = AnyEvent->condvar; 372 my $done = AnyEvent->condvar;
283 373
284 my $pid = fork or exit 5; 374 my $pid = fork or exit 5;
285 375
286 my $w = AnyEvent->child ( 376 my $w = AnyEvent->child (
287 pid => $pid, 377 pid => $pid,
288 cb => sub { 378 cb => sub {
289 my ($pid, $status) = @_; 379 my ($pid, $status) = @_;
290 warn "pid $pid exited with status $status"; 380 warn "pid $pid exited with status $status";
291 $done->send; 381 $done->send;
292 }, 382 },
293 ); 383 );
294 384
295 # do something else, then wait for process exit 385 # do something else, then wait for process exit
296 $done->recv; 386 $done->recv;
297 387
298=head2 CONDITION VARIABLES 388=head2 CONDITION VARIABLES
299 389
300If you are familiar with some event loops you will know that all of them 390If you are familiar with some event loops you will know that all of them
301require you to run some blocking "loop", "run" or similar function that 391require you to run some blocking "loop", "run" or similar function that
307The instrument to do that is called a "condition variable", so called 397The instrument to do that is called a "condition variable", so called
308because they represent a condition that must become true. 398because they represent a condition that must become true.
309 399
310Condition variables can be created by calling the C<< AnyEvent->condvar 400Condition variables can be created by calling the C<< AnyEvent->condvar
311>> method, usually without arguments. The only argument pair allowed is 401>> method, usually without arguments. The only argument pair allowed is
402
312C<cb>, which specifies a callback to be called when the condition variable 403C<cb>, which specifies a callback to be called when the condition variable
313becomes true. 404becomes true, with the condition variable as the first argument (but not
405the results).
314 406
315After creation, the condition variable is "false" until it becomes "true" 407After creation, the condition variable is "false" until it becomes "true"
316by calling the C<send> method (or calling the condition variable as if it 408by calling the C<send> method (or calling the condition variable as if it
317were a callback, read about the caveats in the description for the C<< 409were a callback, read about the caveats in the description for the C<<
318->send >> method). 410->send >> method).
374 466
375 my $done = AnyEvent->condvar; 467 my $done = AnyEvent->condvar;
376 my $delay = AnyEvent->timer (after => 5, cb => $done); 468 my $delay = AnyEvent->timer (after => 5, cb => $done);
377 $done->recv; 469 $done->recv;
378 470
471Example: Imagine an API that returns a condvar and doesn't support
472callbacks. This is how you make a synchronous call, for example from
473the main program:
474
475 use AnyEvent::CouchDB;
476
477 ...
478
479 my @info = $couchdb->info->recv;
480
481And this is how you would just ste a callback to be called whenever the
482results are available:
483
484 $couchdb->info->cb (sub {
485 my @info = $_[0]->recv;
486 });
487
379=head3 METHODS FOR PRODUCERS 488=head3 METHODS FOR PRODUCERS
380 489
381These methods should only be used by the producing side, i.e. the 490These methods should only be used by the producing side, i.e. the
382code/module that eventually sends the signal. Note that it is also 491code/module that eventually sends the signal. Note that it is also
383the producer side which creates the condvar in most cases, but it isn't 492the producer side which creates the condvar in most cases, but it isn't
516=item $bool = $cv->ready 625=item $bool = $cv->ready
517 626
518Returns true when the condition is "true", i.e. whether C<send> or 627Returns true when the condition is "true", i.e. whether C<send> or
519C<croak> have been called. 628C<croak> have been called.
520 629
521=item $cb = $cv->cb ([new callback]) 630=item $cb = $cv->cb ($cb->($cv))
522 631
523This is a mutator function that returns the callback set and optionally 632This is a mutator function that returns the callback set and optionally
524replaces it before doing so. 633replaces it before doing so.
525 634
526The callback will be called when the condition becomes "true", i.e. when 635The callback will be called when the condition becomes "true", i.e. when
527C<send> or C<croak> are called. Calling C<recv> inside the callback 636C<send> or C<croak> are called, with the only argument being the condition
528or at any later time is guaranteed not to block. 637variable itself. Calling C<recv> inside the callback or at any later time
638is guaranteed not to block.
529 639
530=back 640=back
531 641
532=head1 GLOBAL VARIABLES AND FUNCTIONS 642=head1 GLOBAL VARIABLES AND FUNCTIONS
533 643
662=item L<AnyEvent::Util> 772=item L<AnyEvent::Util>
663 773
664Contains various utility functions that replace often-used but blocking 774Contains various utility functions that replace often-used but blocking
665functions such as C<inet_aton> by event-/callback-based versions. 775functions such as C<inet_aton> by event-/callback-based versions.
666 776
667=item L<AnyEvent::Handle>
668
669Provide read and write buffers and manages watchers for reads and writes.
670
671=item L<AnyEvent::Socket> 777=item L<AnyEvent::Socket>
672 778
673Provides various utility functions for (internet protocol) sockets, 779Provides various utility functions for (internet protocol) sockets,
674addresses and name resolution. Also functions to create non-blocking tcp 780addresses and name resolution. Also functions to create non-blocking tcp
675connections or tcp servers, with IPv6 and SRV record support and more. 781connections or tcp servers, with IPv6 and SRV record support and more.
676 782
783=item L<AnyEvent::Handle>
784
785Provide read and write buffers, manages watchers for reads and writes,
786supports raw and formatted I/O, I/O queued and fully transparent and
787non-blocking SSL/TLS.
788
677=item L<AnyEvent::DNS> 789=item L<AnyEvent::DNS>
678 790
679Provides rich asynchronous DNS resolver capabilities. 791Provides rich asynchronous DNS resolver capabilities.
680 792
793=item L<AnyEvent::HTTP>
794
795A simple-to-use HTTP library that is capable of making a lot of concurrent
796HTTP requests.
797
681=item L<AnyEvent::HTTPD> 798=item L<AnyEvent::HTTPD>
682 799
683Provides a simple web application server framework. 800Provides a simple web application server framework.
684 801
685=item L<AnyEvent::FastPing> 802=item L<AnyEvent::FastPing>
686 803
687The fastest ping in the west. 804The fastest ping in the west.
688 805
806=item L<AnyEvent::DBI>
807
808Executes L<DBI> requests asynchronously in a proxy process.
809
810=item L<AnyEvent::AIO>
811
812Truly asynchronous I/O, should be in the toolbox of every event
813programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
814together.
815
816=item L<AnyEvent::BDB>
817
818Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
819L<BDB> and AnyEvent together.
820
821=item L<AnyEvent::GPSD>
822
823A non-blocking interface to gpsd, a daemon delivering GPS information.
824
825=item L<AnyEvent::IGS>
826
827A non-blocking interface to the Internet Go Server protocol (used by
828L<App::IGS>).
829
689=item L<Net::IRC3> 830=item L<AnyEvent::IRC>
690 831
691AnyEvent based IRC client module family. 832AnyEvent based IRC client module family (replacing the older Net::IRC3).
692 833
693=item L<Net::XMPP2> 834=item L<Net::XMPP2>
694 835
695AnyEvent based XMPP (Jabber protocol) module family. 836AnyEvent based XMPP (Jabber protocol) module family.
696 837
705 846
706=item L<Coro> 847=item L<Coro>
707 848
708Has special support for AnyEvent via L<Coro::AnyEvent>. 849Has special support for AnyEvent via L<Coro::AnyEvent>.
709 850
710=item L<AnyEvent::AIO>, L<IO::AIO>
711
712Truly asynchronous I/O, should be in the toolbox of every event
713programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714together.
715
716=item L<AnyEvent::BDB>, L<BDB>
717
718Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719IO::AIO and AnyEvent together.
720
721=item L<IO::Lambda> 851=item L<IO::Lambda>
722 852
723The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 853The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
724 854
725=back 855=back
727=cut 857=cut
728 858
729package AnyEvent; 859package AnyEvent;
730 860
731no warnings; 861no warnings;
732use strict; 862use strict qw(vars subs);
733 863
734use Carp; 864use Carp;
735 865
736our $VERSION = '4.03'; 866our $VERSION = 4.3;
737our $MODEL; 867our $MODEL;
738 868
739our $AUTOLOAD; 869our $AUTOLOAD;
740our @ISA; 870our @ISA;
741 871
742our @REGISTRY; 872our @REGISTRY;
743 873
874our $WIN32;
875
876BEGIN {
877 my $win32 = ! ! ($^O =~ /mswin32/i);
878 eval "sub WIN32(){ $win32 }";
879}
880
744our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 881our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
745 882
746our %PROTOCOL; # (ipv4|ipv6) => (1|2) 883our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
747 884
748{ 885{
749 my $idx; 886 my $idx;
750 $PROTOCOL{$_} = ++$idx 887 $PROTOCOL{$_} = ++$idx
888 for reverse split /\s*,\s*/,
751 for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; 889 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
752} 890}
753 891
754my @models = ( 892my @models = (
755 [EV:: => AnyEvent::Impl::EV::], 893 [EV:: => AnyEvent::Impl::EV::],
756 [Event:: => AnyEvent::Impl::Event::], 894 [Event:: => AnyEvent::Impl::Event::],
765 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 903 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
766 [Wx:: => AnyEvent::Impl::POE::], 904 [Wx:: => AnyEvent::Impl::POE::],
767 [Prima:: => AnyEvent::Impl::POE::], 905 [Prima:: => AnyEvent::Impl::POE::],
768); 906);
769 907
770our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 908our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
771 909
772our @post_detect; 910our @post_detect;
773 911
774sub post_detect(&) { 912sub post_detect(&) {
775 my ($cb) = @_; 913 my ($cb) = @_;
792} 930}
793 931
794sub detect() { 932sub detect() {
795 unless ($MODEL) { 933 unless ($MODEL) {
796 no strict 'refs'; 934 no strict 'refs';
935 local $SIG{__DIE__};
797 936
798 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 937 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
799 my $model = "AnyEvent::Impl::$1"; 938 my $model = "AnyEvent::Impl::$1";
800 if (eval "require $model") { 939 if (eval "require $model") {
801 $MODEL = $model; 940 $MODEL = $model;
835 $MODEL 974 $MODEL
836 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 975 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
837 } 976 }
838 } 977 }
839 978
979 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
980
840 unshift @ISA, $MODEL; 981 unshift @ISA, $MODEL;
841 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 982
983 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
842 984
843 (shift @post_detect)->() while @post_detect; 985 (shift @post_detect)->() while @post_detect;
844 } 986 }
845 987
846 $MODEL 988 $MODEL
856 998
857 my $class = shift; 999 my $class = shift;
858 $class->$func (@_); 1000 $class->$func (@_);
859} 1001}
860 1002
1003# utility function to dup a filehandle. this is used by many backends
1004# to support binding more than one watcher per filehandle (they usually
1005# allow only one watcher per fd, so we dup it to get a different one).
1006sub _dupfh($$$$) {
1007 my ($poll, $fh, $r, $w) = @_;
1008
1009 require Fcntl;
1010
1011 # cygwin requires the fh mode to be matching, unix doesn't
1012 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
1013 : $poll eq "w" ? ($w, ">")
1014 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1015
1016 open my $fh2, "$mode&" . fileno $fh
1017 or die "cannot dup() filehandle: $!";
1018
1019 # we assume CLOEXEC is already set by perl in all important cases
1020
1021 ($fh2, $rw)
1022}
1023
861package AnyEvent::Base; 1024package AnyEvent::Base;
1025
1026# default implementation for now and time
1027
1028BEGIN {
1029 if (eval "use Time::HiRes (); time (); 1") {
1030 *_time = \&Time::HiRes::time;
1031 # if (eval "use POSIX (); (POSIX::times())...
1032 } else {
1033 *_time = sub { time }; # epic fail
1034 }
1035}
1036
1037sub time { _time }
1038sub now { _time }
862 1039
863# default implementation for ->condvar 1040# default implementation for ->condvar
864 1041
865sub condvar { 1042sub condvar {
866 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: 1043 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
887sub AnyEvent::Base::Signal::DESTROY { 1064sub AnyEvent::Base::Signal::DESTROY {
888 my ($signal, $cb) = @{$_[0]}; 1065 my ($signal, $cb) = @{$_[0]};
889 1066
890 delete $SIG_CB{$signal}{$cb}; 1067 delete $SIG_CB{$signal}{$cb};
891 1068
892 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; 1069 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
893} 1070}
894 1071
895# default implementation for ->child 1072# default implementation for ->child
896 1073
897our %PID_CB; 1074our %PID_CB;
924 or Carp::croak "required option 'pid' is missing"; 1101 or Carp::croak "required option 'pid' is missing";
925 1102
926 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1103 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
927 1104
928 unless ($WNOHANG) { 1105 unless ($WNOHANG) {
929 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; 1106 $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
930 } 1107 }
931 1108
932 unless ($CHLD_W) { 1109 unless ($CHLD_W) {
933 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1110 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
934 # child could be a zombie already, so make at least one round 1111 # child could be a zombie already, so make at least one round
1004} 1181}
1005 1182
1006# undocumented/compatibility with pre-3.4 1183# undocumented/compatibility with pre-3.4
1007*broadcast = \&send; 1184*broadcast = \&send;
1008*wait = \&_wait; 1185*wait = \&_wait;
1186
1187=head1 ERROR AND EXCEPTION HANDLING
1188
1189In general, AnyEvent does not do any error handling - it relies on the
1190caller to do that if required. The L<AnyEvent::Strict> module (see also
1191the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
1192checking of all AnyEvent methods, however, which is highly useful during
1193development.
1194
1195As for exception handling (i.e. runtime errors and exceptions thrown while
1196executing a callback), this is not only highly event-loop specific, but
1197also not in any way wrapped by this module, as this is the job of the main
1198program.
1199
1200The pure perl event loop simply re-throws the exception (usually
1201within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
1202$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1203so on.
1204
1205=head1 ENVIRONMENT VARIABLES
1206
1207The following environment variables are used by this module or its
1208submodules:
1209
1210=over 4
1211
1212=item C<PERL_ANYEVENT_VERBOSE>
1213
1214By default, AnyEvent will be completely silent except in fatal
1215conditions. You can set this environment variable to make AnyEvent more
1216talkative.
1217
1218When set to C<1> or higher, causes AnyEvent to warn about unexpected
1219conditions, such as not being able to load the event model specified by
1220C<PERL_ANYEVENT_MODEL>.
1221
1222When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1223model it chooses.
1224
1225=item C<PERL_ANYEVENT_STRICT>
1226
1227AnyEvent does not do much argument checking by default, as thorough
1228argument checking is very costly. Setting this variable to a true value
1229will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1230check the arguments passed to most method calls. If it finds any problems
1231it will croak.
1232
1233In other words, enables "strict" mode.
1234
1235Unlike C<use strict>, it is definitely recommended ot keep it off in
1236production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1237developing programs can be very useful, however.
1238
1239=item C<PERL_ANYEVENT_MODEL>
1240
1241This can be used to specify the event model to be used by AnyEvent, before
1242auto detection and -probing kicks in. It must be a string consisting
1243entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1244and the resulting module name is loaded and if the load was successful,
1245used as event model. If it fails to load AnyEvent will proceed with
1246auto detection and -probing.
1247
1248This functionality might change in future versions.
1249
1250For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1251could start your program like this:
1252
1253 PERL_ANYEVENT_MODEL=Perl perl ...
1254
1255=item C<PERL_ANYEVENT_PROTOCOLS>
1256
1257Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1258for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1259of auto probing).
1260
1261Must be set to a comma-separated list of protocols or address families,
1262current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1263used, and preference will be given to protocols mentioned earlier in the
1264list.
1265
1266This variable can effectively be used for denial-of-service attacks
1267against local programs (e.g. when setuid), although the impact is likely
1268small, as the program has to handle connection errors already-
1269
1270Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1271but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1272- only support IPv4, never try to resolve or contact IPv6
1273addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1274IPv6, but prefer IPv6 over IPv4.
1275
1276=item C<PERL_ANYEVENT_EDNS0>
1277
1278Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1279for DNS. This extension is generally useful to reduce DNS traffic, but
1280some (broken) firewalls drop such DNS packets, which is why it is off by
1281default.
1282
1283Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1284EDNS0 in its DNS requests.
1285
1286=item C<PERL_ANYEVENT_MAX_FORKS>
1287
1288The maximum number of child processes that C<AnyEvent::Util::fork_call>
1289will create in parallel.
1290
1291=back
1009 1292
1010=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1293=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1011 1294
1012This is an advanced topic that you do not normally need to use AnyEvent in 1295This is an advanced topic that you do not normally need to use AnyEvent in
1013a module. This section is only of use to event loop authors who want to 1296a module. This section is only of use to event loop authors who want to
1047 1330
1048I<rxvt-unicode> also cheats a bit by not providing blocking access to 1331I<rxvt-unicode> also cheats a bit by not providing blocking access to
1049condition variables: code blocking while waiting for a condition will 1332condition variables: code blocking while waiting for a condition will
1050C<die>. This still works with most modules/usages, and blocking calls must 1333C<die>. This still works with most modules/usages, and blocking calls must
1051not be done in an interactive application, so it makes sense. 1334not be done in an interactive application, so it makes sense.
1052
1053=head1 ENVIRONMENT VARIABLES
1054
1055The following environment variables are used by this module:
1056
1057=over 4
1058
1059=item C<PERL_ANYEVENT_VERBOSE>
1060
1061By default, AnyEvent will be completely silent except in fatal
1062conditions. You can set this environment variable to make AnyEvent more
1063talkative.
1064
1065When set to C<1> or higher, causes AnyEvent to warn about unexpected
1066conditions, such as not being able to load the event model specified by
1067C<PERL_ANYEVENT_MODEL>.
1068
1069When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1070model it chooses.
1071
1072=item C<PERL_ANYEVENT_MODEL>
1073
1074This can be used to specify the event model to be used by AnyEvent, before
1075auto detection and -probing kicks in. It must be a string consisting
1076entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1077and the resulting module name is loaded and if the load was successful,
1078used as event model. If it fails to load AnyEvent will proceed with
1079auto detection and -probing.
1080
1081This functionality might change in future versions.
1082
1083For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1084could start your program like this:
1085
1086 PERL_ANYEVENT_MODEL=Perl perl ...
1087
1088=item C<PERL_ANYEVENT_PROTOCOLS>
1089
1090Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1091for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1092of auto probing).
1093
1094Must be set to a comma-separated list of protocols or address families,
1095current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1096used, and preference will be given to protocols mentioned earlier in the
1097list.
1098
1099This variable can effectively be used for denial-of-service attacks
1100against local programs (e.g. when setuid), although the impact is likely
1101small, as the program has to handle connection errors already-
1102
1103Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1104but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1105- only support IPv4, never try to resolve or contact IPv6
1106addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1107IPv6, but prefer IPv6 over IPv4.
1108
1109=item C<PERL_ANYEVENT_EDNS0>
1110
1111Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1112for DNS. This extension is generally useful to reduce DNS traffic, but
1113some (broken) firewalls drop such DNS packets, which is why it is off by
1114default.
1115
1116Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1117EDNS0 in its DNS requests.
1118
1119=back
1120 1335
1121=head1 EXAMPLE PROGRAM 1336=head1 EXAMPLE PROGRAM
1122 1337
1123The following program uses an I/O watcher to read data from STDIN, a timer 1338The following program uses an I/O watcher to read data from STDIN, a timer
1124to display a message once per second, and a condition variable to quit the 1339to display a message once per second, and a condition variable to quit the
1318watcher. 1533watcher.
1319 1534
1320=head3 Results 1535=head3 Results
1321 1536
1322 name watchers bytes create invoke destroy comment 1537 name watchers bytes create invoke destroy comment
1323 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1538 EV/EV 400000 224 0.47 0.43 0.27 EV native interface
1324 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1539 EV/Any 100000 224 2.88 0.44 0.27 EV + AnyEvent watchers
1325 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1540 CoroEV/Any 100000 224 2.85 0.45 0.28 coroutines + Coro::Signal
1326 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1541 Perl/Any 100000 452 4.14 0.75 0.99 pure perl implementation
1327 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1542 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1328 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1543 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1329 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1544 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1330 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1545 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1331 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1546 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1332 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1547 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1333 1548
1334=head3 Discussion 1549=head3 Discussion
1335 1550
1336The benchmark does I<not> measure scalability of the event loop very 1551The benchmark does I<not> measure scalability of the event loop very
1337well. For example, a select-based event loop (such as the pure perl one) 1552well. For example, a select-based event loop (such as the pure perl one)
1539watchers, as the management overhead dominates. 1754watchers, as the management overhead dominates.
1540 1755
1541=back 1756=back
1542 1757
1543 1758
1759=head1 SIGNALS
1760
1761AnyEvent currently installs handlers for these signals:
1762
1763=over 4
1764
1765=item SIGCHLD
1766
1767A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1768emulation for event loops that do not support them natively. Also, some
1769event loops install a similar handler.
1770
1771=item SIGPIPE
1772
1773A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1774when AnyEvent gets loaded.
1775
1776The rationale for this is that AnyEvent users usually do not really depend
1777on SIGPIPE delivery (which is purely an optimisation for shell use, or
1778badly-written programs), but C<SIGPIPE> can cause spurious and rare
1779program exits as a lot of people do not expect C<SIGPIPE> when writing to
1780some random socket.
1781
1782The rationale for installing a no-op handler as opposed to ignoring it is
1783that this way, the handler will be restored to defaults on exec.
1784
1785Feel free to install your own handler, or reset it to defaults.
1786
1787=back
1788
1789=cut
1790
1791$SIG{PIPE} = sub { }
1792 unless defined $SIG{PIPE};
1793
1794
1544=head1 FORK 1795=head1 FORK
1545 1796
1546Most event libraries are not fork-safe. The ones who are usually are 1797Most event libraries are not fork-safe. The ones who are usually are
1547because they rely on inefficient but fork-safe C<select> or C<poll> 1798because they rely on inefficient but fork-safe C<select> or C<poll>
1548calls. Only L<EV> is fully fork-aware. 1799calls. Only L<EV> is fully fork-aware.
1561specified in the variable. 1812specified in the variable.
1562 1813
1563You can make AnyEvent completely ignore this variable by deleting it 1814You can make AnyEvent completely ignore this variable by deleting it
1564before the first watcher gets created, e.g. with a C<BEGIN> block: 1815before the first watcher gets created, e.g. with a C<BEGIN> block:
1565 1816
1566 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1817 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1567 1818
1568 use AnyEvent; 1819 use AnyEvent;
1569 1820
1570Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1821Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1571be used to probe what backend is used and gain other information (which is 1822be used to probe what backend is used and gain other information (which is
1572probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1823probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1824$ENV{PERL_ANYEGENT_STRICT}.
1825
1826
1827=head1 BUGS
1828
1829Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1830to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1831and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1832mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
1833pronounced).
1573 1834
1574 1835
1575=head1 SEE ALSO 1836=head1 SEE ALSO
1576 1837
1577Utility functions: L<AnyEvent::Util>. 1838Utility functions: L<AnyEvent::Util>.
1594Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. 1855Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1595 1856
1596 1857
1597=head1 AUTHOR 1858=head1 AUTHOR
1598 1859
1599 Marc Lehmann <schmorp@schmorp.de> 1860 Marc Lehmann <schmorp@schmorp.de>
1600 http://home.schmorp.de/ 1861 http://home.schmorp.de/
1601 1862
1602=cut 1863=cut
1603 1864
16041 18651
1605 1866

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