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1.1 |
=head1 NAME |
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AnyEvent - provide framework for multiple event loops |
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EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl - various supported event loops |
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=head1 SYNOPSIS |
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use AnyEvent; |
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my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
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... |
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}); |
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my $w = AnyEvent->timer (after => $seconds, cb => sub { |
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... |
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}); |
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my $w = AnyEvent->condvar; # stores wether a condition was flagged |
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$w->wait; # enters "main loop" till $condvar gets ->broadcast |
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$w->broadcast; # wake up current and all future wait's |
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=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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nowadays. So what is different about AnyEvent? |
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Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
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policy> and AnyEvent is I<small and efficient>. |
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First and foremost, I<AnyEvent is not an event model> itself, it only |
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interfaces to whatever event model the main program happens to use in a |
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pragmatic way. For event models and certain classes of immortals alike, |
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the statement "there can only be one" is a bitter reality, and AnyEvent |
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helps hiding the differences. |
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The goal of AnyEvent is to offer module authors the ability to do event |
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programming (waiting for I/O or timer events) without subscribing to a |
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religion, a way of living, and most importantly: without forcing your |
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module users into the same thing by forcing them to use the same event |
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model you use. |
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For modules like POE or IO::Async (which is actually doing all I/O |
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I<synchronously>...), using them in your module is like joining a |
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cult: After you joined, you are dependent on them and you cannot use |
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anything else, as it is simply incompatible to everything that isn't |
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itself. |
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AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk |
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works fine etc. etc. but none of these work together with the rest: POE |
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+ IO::Async? no go. Tk + Event? no go. If your module uses one of |
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those, every user of your module has to use it, too. If your module |
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uses AnyEvent, it works transparently with all event models it supports |
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(including stuff like POE and IO::Async). |
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In addition of being free of having to use I<the one and only true event |
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model>, AnyEvent also is free of bloat and policy: with POE or similar |
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modules, you get an enourmous amount of code and strict rules you have |
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to follow. AnyEvent, on the other hand, is lean and to the point by only |
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offering the functionality that is useful, in as thin as a wrapper as |
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technically possible. |
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Of course, if you want lots of policy (this can arguably be somewhat |
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useful) and you want to force your users to use the one and only event |
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model, you should I<not> use this module. |
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1.1 |
=head1 DESCRIPTION |
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L<AnyEvent> provides an identical interface to multiple event loops. This |
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allows module authors to utilise an event loop without forcing module |
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users to use the same event loop (as only a single event loop can coexist |
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peacefully at any one time). |
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The interface itself is vaguely similar but not identical to the Event |
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module. |
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On the first call of any method, the module tries to detect the currently |
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loaded event loop by probing wether any of the following modules is |
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loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, L<Event>, L<Glib>, L<Tk>. The |
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first one found is used. If none are found, the module tries to load these |
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modules in the order given. The first one that could be successfully |
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loaded will be used. If still none could be found, AnyEvent will fall back |
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to a pure-perl event loop, which is also not very efficient. |
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Because AnyEvent first checks for modules that are already loaded, loading |
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an Event model explicitly before first using AnyEvent will likely make |
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that model the default. For example: |
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use Tk; |
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use AnyEvent; |
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# .. AnyEvent will likely default to Tk |
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The pure-perl implementation of AnyEvent is called |
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C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
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explicitly. |
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=head1 WATCHERS |
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AnyEvent has the central concept of a I<watcher>, which is an object that |
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stores relevant data for each kind of event you are waiting for, such as |
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the callback to call, the filehandle to watch, etc. |
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These watchers are normal Perl objects with normal Perl lifetime. After |
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creating a watcher it will immediately "watch" for events and invoke |
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the callback. To disable the watcher you have to destroy it (e.g. by |
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setting the variable that stores it to C<undef> or otherwise deleting all |
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references to it). |
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All watchers are created by calling a method on the C<AnyEvent> class. |
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=head2 IO WATCHERS |
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You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
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the following mandatory arguments: |
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C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
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events. C<poll> must be a string that is either C<r> or C<w>, that creates |
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1.36 |
a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback |
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1.14 |
to invoke everytime the filehandle becomes ready. |
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Filehandles will be kept alive, so as long as the watcher exists, the |
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filehandle exists, too. |
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Example: |
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# wait for readability of STDIN, then read a line and disable the watcher |
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my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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chomp (my $input = <STDIN>); |
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warn "read: $input\n"; |
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undef $w; |
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}); |
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1.19 |
=head2 TIME WATCHERS |
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You can create a time watcher by calling the C<< AnyEvent->timer >> |
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method with the following mandatory arguments: |
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C<after> after how many seconds (fractions are supported) should the timer |
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activate. C<cb> the callback to invoke. |
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The timer callback will be invoked at most once: if you want a repeating |
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timer you have to create a new watcher (this is a limitation by both Tk |
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and Glib). |
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Example: |
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# fire an event after 7.7 seconds |
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my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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warn "timeout\n"; |
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}); |
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# to cancel the timer: |
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1.37 |
undef $w; |
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1.14 |
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=head2 CONDITION WATCHERS |
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Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
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method without any arguments. |
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A condition watcher watches for a condition - precisely that the C<< |
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->broadcast >> method has been called. |
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Note that condition watchers recurse into the event loop - if you have |
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two watchers that call C<< ->wait >> in a round-robbin fashion, you |
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lose. Therefore, condition watchers are good to export to your caller, but |
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you should avoid making a blocking wait, at least in callbacks, as this |
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usually asks for trouble. |
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1.14 |
The watcher has only two methods: |
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1.1 |
=over 4 |
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=item $cv->wait |
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Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
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called on c<$cv>, while servicing other watchers normally. |
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You can only wait once on a condition - additional calls will return |
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immediately. |
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Not all event models support a blocking wait - some die in that case |
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(programs might want to do that so they stay interactive), so I<if you |
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are using this from a module, never require a blocking wait>, but let the |
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caller decide wether the call will block or not (for example, by coupling |
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condition variables with some kind of request results and supporting |
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callbacks so the caller knows that getting the result will not block, |
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while still suppporting blocking waits if the caller so desires). |
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Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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sensibly have two C<< ->wait >>'s in parallel, as that would require |
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multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event> |
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explicitly support concurrent C<< ->wait >>'s from different coroutines, |
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however). |
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1.14 |
=item $cv->broadcast |
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Flag the condition as ready - a running C<< ->wait >> and all further |
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calls to C<wait> will return after this method has been called. If nobody |
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is waiting the broadcast will be remembered.. |
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Example: |
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# wait till the result is ready |
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my $result_ready = AnyEvent->condvar; |
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# do something such as adding a timer |
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# or socket watcher the calls $result_ready->broadcast |
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# when the "result" is ready. |
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$result_ready->wait; |
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=back |
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1.19 |
=head2 SIGNAL WATCHERS |
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You can listen for signals using a signal watcher, C<signal> is the signal |
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I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
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1.22 |
together into one callback invocation, and callback invocation might or |
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1.20 |
might not be asynchronous. |
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1.19 |
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These watchers might use C<%SIG>, so programs overwriting those signals |
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directly will likely not work correctly. |
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Example: exit on SIGINT |
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my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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1.20 |
=head2 CHILD PROCESS WATCHERS |
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You can also listen for the status of a child process specified by the |
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1.31 |
C<pid> argument (or any child if the pid argument is 0). The watcher will |
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trigger as often as status change for the child are received. This works |
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1.32 |
by installing a signal handler for C<SIGCHLD>. The callback will be called with |
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the pid and exit status (as returned by waitpid). |
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1.20 |
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Example: wait for pid 1333 |
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my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
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1.16 |
=head1 GLOBALS |
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=over 4 |
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=item $AnyEvent::MODEL |
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Contains C<undef> until the first watcher is being created. Then it |
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contains the event model that is being used, which is the name of the |
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Perl class implementing the model. This class is usually one of the |
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C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
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AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
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The known classes so far are: |
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1.33 |
AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
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1.50 |
AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
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1.33 |
AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
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1.29 |
AnyEvent::Impl::Event based on Event, also second best choice :) |
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1.48 |
AnyEvent::Impl::Glib based on Glib, third-best choice. |
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1.16 |
AnyEvent::Impl::Tk based on Tk, very bad choice. |
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1.48 |
AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
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1.16 |
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1.19 |
=item AnyEvent::detect |
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Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
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necessary. You should only call this function right before you would have |
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created an AnyEvent watcher anyway, that is, very late at runtime. |
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1.16 |
=back |
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1.14 |
=head1 WHAT TO DO IN A MODULE |
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As a module author, you should "use AnyEvent" and call AnyEvent methods |
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freely, but you should not load a specific event module or rely on it. |
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Be careful when you create watchers in the module body - Anyevent will |
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decide which event module to use as soon as the first method is called, so |
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by calling AnyEvent in your module body you force the user of your module |
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to load the event module first. |
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=head1 WHAT TO DO IN THE MAIN PROGRAM |
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There will always be a single main program - the only place that should |
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dictate which event model to use. |
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If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
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do anything special and let AnyEvent decide which implementation to chose. |
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If the main program relies on a specific event model (for example, in Gtk2 |
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programs you have to rely on either Glib or Glib::Event), you should load |
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it before loading AnyEvent or any module that uses it, generally, as early |
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as possible. The reason is that modules might create watchers when they |
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are loaded, and AnyEvent will decide on the event model to use as soon as |
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it creates watchers, and it might chose the wrong one unless you load the |
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correct one yourself. |
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You can chose to use a rather inefficient pure-perl implementation by |
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loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
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generally better. |
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1.1 |
=cut |
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package AnyEvent; |
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1.2 |
no warnings; |
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1.19 |
use strict; |
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1.24 |
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1.1 |
use Carp; |
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1.51 |
our $VERSION = '3.1'; |
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1.2 |
our $MODEL; |
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1.1 |
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1.2 |
our $AUTOLOAD; |
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our @ISA; |
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1.1 |
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1.7 |
our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
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1.8 |
our @REGISTRY; |
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1.1 |
my @models = ( |
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1.33 |
[Coro::EV:: => AnyEvent::Impl::CoroEV::], |
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1.50 |
[Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
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1.33 |
[EV:: => AnyEvent::Impl::EV::], |
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1.18 |
[Event:: => AnyEvent::Impl::Event::], |
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[Glib:: => AnyEvent::Impl::Glib::], |
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[Tk:: => AnyEvent::Impl::Tk::], |
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[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
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1.1 |
); |
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1.19 |
our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
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1.3 |
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1.19 |
sub detect() { |
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unless ($MODEL) { |
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no strict 'refs'; |
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1.1 |
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1.2 |
# check for already loaded models |
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1.8 |
for (@REGISTRY, @models) { |
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my ($package, $model) = @$_; |
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1.7 |
if (${"$package\::VERSION"} > 0) { |
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1.8 |
if (eval "require $model") { |
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$MODEL = $model; |
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warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
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last; |
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} |
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1.2 |
} |
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1.1 |
} |
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1.2 |
unless ($MODEL) { |
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# try to load a model |
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1.8 |
for (@REGISTRY, @models) { |
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my ($package, $model) = @$_; |
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1.21 |
if (eval "require $package" |
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and ${"$package\::VERSION"} > 0 |
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and eval "require $model") { |
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1.8 |
$MODEL = $model; |
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|
|
warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
360 |
|
|
last; |
361 |
|
|
} |
362 |
root |
1.2 |
} |
363 |
|
|
|
364 |
|
|
$MODEL |
365 |
root |
1.35 |
or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event), Glib or Tk."; |
366 |
root |
1.1 |
} |
367 |
root |
1.19 |
|
368 |
|
|
unshift @ISA, $MODEL; |
369 |
|
|
push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
370 |
root |
1.1 |
} |
371 |
|
|
|
372 |
root |
1.19 |
$MODEL |
373 |
|
|
} |
374 |
|
|
|
375 |
|
|
sub AUTOLOAD { |
376 |
|
|
(my $func = $AUTOLOAD) =~ s/.*://; |
377 |
|
|
|
378 |
|
|
$method{$func} |
379 |
|
|
or croak "$func: not a valid method for AnyEvent objects"; |
380 |
|
|
|
381 |
|
|
detect unless $MODEL; |
382 |
root |
1.2 |
|
383 |
|
|
my $class = shift; |
384 |
root |
1.18 |
$class->$func (@_); |
385 |
root |
1.1 |
} |
386 |
|
|
|
387 |
root |
1.19 |
package AnyEvent::Base; |
388 |
|
|
|
389 |
root |
1.20 |
# default implementation for ->condvar, ->wait, ->broadcast |
390 |
|
|
|
391 |
|
|
sub condvar { |
392 |
|
|
bless \my $flag, "AnyEvent::Base::CondVar" |
393 |
|
|
} |
394 |
|
|
|
395 |
|
|
sub AnyEvent::Base::CondVar::broadcast { |
396 |
|
|
${$_[0]}++; |
397 |
|
|
} |
398 |
|
|
|
399 |
|
|
sub AnyEvent::Base::CondVar::wait { |
400 |
|
|
AnyEvent->one_event while !${$_[0]}; |
401 |
|
|
} |
402 |
|
|
|
403 |
|
|
# default implementation for ->signal |
404 |
root |
1.19 |
|
405 |
|
|
our %SIG_CB; |
406 |
|
|
|
407 |
|
|
sub signal { |
408 |
|
|
my (undef, %arg) = @_; |
409 |
|
|
|
410 |
|
|
my $signal = uc $arg{signal} |
411 |
|
|
or Carp::croak "required option 'signal' is missing"; |
412 |
|
|
|
413 |
root |
1.31 |
$SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
414 |
root |
1.19 |
$SIG{$signal} ||= sub { |
415 |
root |
1.20 |
$_->() for values %{ $SIG_CB{$signal} || {} }; |
416 |
root |
1.19 |
}; |
417 |
|
|
|
418 |
root |
1.20 |
bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
419 |
root |
1.19 |
} |
420 |
|
|
|
421 |
|
|
sub AnyEvent::Base::Signal::DESTROY { |
422 |
|
|
my ($signal, $cb) = @{$_[0]}; |
423 |
|
|
|
424 |
|
|
delete $SIG_CB{$signal}{$cb}; |
425 |
|
|
|
426 |
|
|
$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
427 |
|
|
} |
428 |
|
|
|
429 |
root |
1.20 |
# default implementation for ->child |
430 |
|
|
|
431 |
|
|
our %PID_CB; |
432 |
|
|
our $CHLD_W; |
433 |
root |
1.37 |
our $CHLD_DELAY_W; |
434 |
root |
1.20 |
our $PID_IDLE; |
435 |
|
|
our $WNOHANG; |
436 |
|
|
|
437 |
|
|
sub _child_wait { |
438 |
root |
1.38 |
while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
439 |
root |
1.32 |
$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
440 |
|
|
(values %{ $PID_CB{0} || {} }); |
441 |
root |
1.20 |
} |
442 |
|
|
|
443 |
|
|
undef $PID_IDLE; |
444 |
|
|
} |
445 |
|
|
|
446 |
root |
1.37 |
sub _sigchld { |
447 |
|
|
# make sure we deliver these changes "synchronous" with the event loop. |
448 |
|
|
$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
449 |
|
|
undef $CHLD_DELAY_W; |
450 |
|
|
&_child_wait; |
451 |
|
|
}); |
452 |
|
|
} |
453 |
|
|
|
454 |
root |
1.20 |
sub child { |
455 |
|
|
my (undef, %arg) = @_; |
456 |
|
|
|
457 |
root |
1.31 |
defined (my $pid = $arg{pid} + 0) |
458 |
root |
1.20 |
or Carp::croak "required option 'pid' is missing"; |
459 |
|
|
|
460 |
|
|
$PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
461 |
|
|
|
462 |
|
|
unless ($WNOHANG) { |
463 |
|
|
$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
464 |
|
|
} |
465 |
|
|
|
466 |
root |
1.23 |
unless ($CHLD_W) { |
467 |
root |
1.37 |
$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
468 |
|
|
# child could be a zombie already, so make at least one round |
469 |
|
|
&_sigchld; |
470 |
root |
1.23 |
} |
471 |
root |
1.20 |
|
472 |
|
|
bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
473 |
|
|
} |
474 |
|
|
|
475 |
|
|
sub AnyEvent::Base::Child::DESTROY { |
476 |
|
|
my ($pid, $cb) = @{$_[0]}; |
477 |
|
|
|
478 |
|
|
delete $PID_CB{$pid}{$cb}; |
479 |
|
|
delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
480 |
|
|
|
481 |
|
|
undef $CHLD_W unless keys %PID_CB; |
482 |
|
|
} |
483 |
|
|
|
484 |
root |
1.8 |
=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
485 |
|
|
|
486 |
|
|
If you need to support another event library which isn't directly |
487 |
|
|
supported by AnyEvent, you can supply your own interface to it by |
488 |
root |
1.11 |
pushing, before the first watcher gets created, the package name of |
489 |
root |
1.8 |
the event module and the package name of the interface to use onto |
490 |
|
|
C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
491 |
|
|
AnyEvent. |
492 |
|
|
|
493 |
|
|
Example: |
494 |
|
|
|
495 |
|
|
push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
496 |
|
|
|
497 |
root |
1.12 |
This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
498 |
|
|
package/class when it finds the C<urxvt> package/module is loaded. When |
499 |
|
|
AnyEvent is loaded and asked to find a suitable event model, it will |
500 |
|
|
first check for the presence of urxvt. |
501 |
|
|
|
502 |
root |
1.19 |
The class should provide implementations for all watcher types (see |
503 |
root |
1.12 |
L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
504 |
|
|
(Source code) and so on for actual examples, use C<perldoc -m |
505 |
|
|
AnyEvent::Impl::Glib> to see the sources). |
506 |
root |
1.8 |
|
507 |
root |
1.12 |
The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
508 |
|
|
uses the above line as-is. An interface isn't included in AnyEvent |
509 |
root |
1.8 |
because it doesn't make sense outside the embedded interpreter inside |
510 |
|
|
I<rxvt-unicode>, and it is updated and maintained as part of the |
511 |
|
|
I<rxvt-unicode> distribution. |
512 |
|
|
|
513 |
root |
1.12 |
I<rxvt-unicode> also cheats a bit by not providing blocking access to |
514 |
|
|
condition variables: code blocking while waiting for a condition will |
515 |
|
|
C<die>. This still works with most modules/usages, and blocking calls must |
516 |
root |
1.25 |
not be in an interactive application, so it makes sense. |
517 |
root |
1.12 |
|
518 |
root |
1.7 |
=head1 ENVIRONMENT VARIABLES |
519 |
|
|
|
520 |
|
|
The following environment variables are used by this module: |
521 |
|
|
|
522 |
|
|
C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
523 |
|
|
model gets used. |
524 |
|
|
|
525 |
root |
1.2 |
=head1 EXAMPLE |
526 |
|
|
|
527 |
|
|
The following program uses an io watcher to read data from stdin, a timer |
528 |
|
|
to display a message once per second, and a condvar to exit the program |
529 |
|
|
when the user enters quit: |
530 |
|
|
|
531 |
|
|
use AnyEvent; |
532 |
|
|
|
533 |
|
|
my $cv = AnyEvent->condvar; |
534 |
|
|
|
535 |
|
|
my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
536 |
|
|
warn "io event <$_[0]>\n"; # will always output <r> |
537 |
|
|
chomp (my $input = <STDIN>); # read a line |
538 |
|
|
warn "read: $input\n"; # output what has been read |
539 |
|
|
$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
540 |
|
|
}); |
541 |
|
|
|
542 |
|
|
my $time_watcher; # can only be used once |
543 |
|
|
|
544 |
|
|
sub new_timer { |
545 |
|
|
$timer = AnyEvent->timer (after => 1, cb => sub { |
546 |
|
|
warn "timeout\n"; # print 'timeout' about every second |
547 |
|
|
&new_timer; # and restart the time |
548 |
|
|
}); |
549 |
|
|
} |
550 |
|
|
|
551 |
|
|
new_timer; # create first timer |
552 |
|
|
|
553 |
|
|
$cv->wait; # wait until user enters /^q/i |
554 |
|
|
|
555 |
root |
1.5 |
=head1 REAL-WORLD EXAMPLE |
556 |
|
|
|
557 |
|
|
Consider the L<Net::FCP> module. It features (among others) the following |
558 |
|
|
API calls, which are to freenet what HTTP GET requests are to http: |
559 |
|
|
|
560 |
|
|
my $data = $fcp->client_get ($url); # blocks |
561 |
|
|
|
562 |
|
|
my $transaction = $fcp->txn_client_get ($url); # does not block |
563 |
|
|
$transaction->cb ( sub { ... } ); # set optional result callback |
564 |
|
|
my $data = $transaction->result; # possibly blocks |
565 |
|
|
|
566 |
|
|
The C<client_get> method works like C<LWP::Simple::get>: it requests the |
567 |
|
|
given URL and waits till the data has arrived. It is defined to be: |
568 |
|
|
|
569 |
|
|
sub client_get { $_[0]->txn_client_get ($_[1])->result } |
570 |
|
|
|
571 |
|
|
And in fact is automatically generated. This is the blocking API of |
572 |
|
|
L<Net::FCP>, and it works as simple as in any other, similar, module. |
573 |
|
|
|
574 |
|
|
More complicated is C<txn_client_get>: It only creates a transaction |
575 |
|
|
(completion, result, ...) object and initiates the transaction. |
576 |
|
|
|
577 |
|
|
my $txn = bless { }, Net::FCP::Txn::; |
578 |
|
|
|
579 |
|
|
It also creates a condition variable that is used to signal the completion |
580 |
|
|
of the request: |
581 |
|
|
|
582 |
|
|
$txn->{finished} = AnyAvent->condvar; |
583 |
|
|
|
584 |
|
|
It then creates a socket in non-blocking mode. |
585 |
|
|
|
586 |
|
|
socket $txn->{fh}, ...; |
587 |
|
|
fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
588 |
|
|
connect $txn->{fh}, ... |
589 |
|
|
and !$!{EWOULDBLOCK} |
590 |
|
|
and !$!{EINPROGRESS} |
591 |
|
|
and Carp::croak "unable to connect: $!\n"; |
592 |
|
|
|
593 |
root |
1.6 |
Then it creates a write-watcher which gets called whenever an error occurs |
594 |
root |
1.5 |
or the connection succeeds: |
595 |
|
|
|
596 |
|
|
$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
597 |
|
|
|
598 |
|
|
And returns this transaction object. The C<fh_ready_w> callback gets |
599 |
|
|
called as soon as the event loop detects that the socket is ready for |
600 |
|
|
writing. |
601 |
|
|
|
602 |
|
|
The C<fh_ready_w> method makes the socket blocking again, writes the |
603 |
|
|
request data and replaces the watcher by a read watcher (waiting for reply |
604 |
|
|
data). The actual code is more complicated, but that doesn't matter for |
605 |
|
|
this example: |
606 |
|
|
|
607 |
|
|
fcntl $txn->{fh}, F_SETFL, 0; |
608 |
|
|
syswrite $txn->{fh}, $txn->{request} |
609 |
|
|
or die "connection or write error"; |
610 |
|
|
$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
611 |
|
|
|
612 |
|
|
Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
613 |
|
|
result and signals any possible waiters that the request ahs finished: |
614 |
|
|
|
615 |
|
|
sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
616 |
|
|
|
617 |
|
|
if (end-of-file or data complete) { |
618 |
|
|
$txn->{result} = $txn->{buf}; |
619 |
|
|
$txn->{finished}->broadcast; |
620 |
root |
1.6 |
$txb->{cb}->($txn) of $txn->{cb}; # also call callback |
621 |
root |
1.5 |
} |
622 |
|
|
|
623 |
|
|
The C<result> method, finally, just waits for the finished signal (if the |
624 |
|
|
request was already finished, it doesn't wait, of course, and returns the |
625 |
|
|
data: |
626 |
|
|
|
627 |
|
|
$txn->{finished}->wait; |
628 |
root |
1.6 |
return $txn->{result}; |
629 |
root |
1.5 |
|
630 |
|
|
The actual code goes further and collects all errors (C<die>s, exceptions) |
631 |
|
|
that occured during request processing. The C<result> method detects |
632 |
|
|
wether an exception as thrown (it is stored inside the $txn object) |
633 |
|
|
and just throws the exception, which means connection errors and other |
634 |
|
|
problems get reported tot he code that tries to use the result, not in a |
635 |
|
|
random callback. |
636 |
|
|
|
637 |
|
|
All of this enables the following usage styles: |
638 |
|
|
|
639 |
|
|
1. Blocking: |
640 |
|
|
|
641 |
|
|
my $data = $fcp->client_get ($url); |
642 |
|
|
|
643 |
root |
1.49 |
2. Blocking, but running in parallel: |
644 |
root |
1.5 |
|
645 |
|
|
my @datas = map $_->result, |
646 |
|
|
map $fcp->txn_client_get ($_), |
647 |
|
|
@urls; |
648 |
|
|
|
649 |
|
|
Both blocking examples work without the module user having to know |
650 |
|
|
anything about events. |
651 |
|
|
|
652 |
root |
1.49 |
3a. Event-based in a main program, using any supported event module: |
653 |
root |
1.5 |
|
654 |
root |
1.49 |
use EV; |
655 |
root |
1.5 |
|
656 |
|
|
$fcp->txn_client_get ($url)->cb (sub { |
657 |
|
|
my $txn = shift; |
658 |
|
|
my $data = $txn->result; |
659 |
|
|
... |
660 |
|
|
}); |
661 |
|
|
|
662 |
root |
1.49 |
EV::loop; |
663 |
root |
1.5 |
|
664 |
|
|
3b. The module user could use AnyEvent, too: |
665 |
|
|
|
666 |
|
|
use AnyEvent; |
667 |
|
|
|
668 |
|
|
my $quit = AnyEvent->condvar; |
669 |
|
|
|
670 |
|
|
$fcp->txn_client_get ($url)->cb (sub { |
671 |
|
|
... |
672 |
|
|
$quit->broadcast; |
673 |
|
|
}); |
674 |
|
|
|
675 |
|
|
$quit->wait; |
676 |
|
|
|
677 |
root |
1.2 |
=head1 SEE ALSO |
678 |
|
|
|
679 |
root |
1.49 |
Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
680 |
|
|
L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
681 |
root |
1.5 |
|
682 |
root |
1.49 |
Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
683 |
|
|
L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
684 |
|
|
L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
685 |
root |
1.5 |
|
686 |
root |
1.49 |
Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
687 |
root |
1.2 |
|
688 |
|
|
=head1 |
689 |
|
|
|
690 |
|
|
=cut |
691 |
|
|
|
692 |
|
|
1 |
693 |
root |
1.1 |
|