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=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 $w = AnyEvent->condvar; # stores whether a condition was flagged |
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$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: In general, |
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only one event loop can be active at the same time in a process. AnyEvent |
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helps hiding the differences between those event loops. |
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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 a total misnomer as it is |
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actually doing all I/O I<synchronously>...), using them in your module is |
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like joining a cult: After you joined, you are dependent on them and you |
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cannot use anything else, as it is simply incompatible to everything that |
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isn't itself. What's worse, all the potential users of your module are |
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I<also> forced to use the same event loop you use. |
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AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
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fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
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with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if |
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your module uses one of those, every user of your module has to use it, |
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too. But if your module uses AnyEvent, it works transparently with all |
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event models it supports (including stuff like POE and IO::Async, as long |
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as those use one of the supported event loops. It is trivial to add new |
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event loops to AnyEvent, too, so it is future-proof). |
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In addition to 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 to |
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follow. AnyEvent, on the other hand, is lean and up to the point, by only |
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offering the functionality that is necessary, 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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=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 L<Event> |
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module. |
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During the first call of any watcher-creation method, the module tries |
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to detect the currently loaded event loop by probing whether one of the |
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following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
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L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found, |
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the module tries to load these modules in the stated order. The first one |
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that can be successfully loaded will be used. If, after this, still none |
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could be found, AnyEvent will fall back to a pure-perl event loop, which |
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is not very efficient, but should work everywhere. |
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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 I<likely> means that, if any module loads another event model and |
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starts using it, all bets are off. Maybe you should tell their authors to |
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use AnyEvent so their modules work together with others seamlessly... |
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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 the |
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callback when the event occurs (of course, only when the event model |
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is in control). |
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To disable the watcher you have to destroy it (e.g. by setting the |
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variable you store it in to C<undef> or otherwise deleting all references |
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to it). |
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All watchers are created by calling a method on the C<AnyEvent> class. |
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Many watchers either are used with "recursion" (repeating timers for |
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example), or need to refer to their watcher object in other ways. |
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An any way to achieve that is this pattern: |
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my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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# you can use $w here, for example to undef it |
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undef $w; |
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}); |
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Note that C<my $w; $w => combination. This is necessary because in Perl, |
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my variables are only visible after the statement in which they are |
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declared. |
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=head2 IO WATCHERS |
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You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
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with the following mandatory key-value pairs as arguments: |
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C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for |
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events. C<poll> must be a string that is either C<r> or C<w>, which |
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creates a watcher waiting for "r"eadable or "w"ritable events, |
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respectively. C<cb> is the callback to invoke each time the file handle |
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becomes ready. |
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File handles will be kept alive, so as long as the watcher exists, the |
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file handle exists, too. |
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It is not allowed to close a file handle as long as any watcher is active |
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on the underlying file descriptor. |
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Some event loops issue spurious readyness notifications, so you should |
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always use non-blocking calls when reading/writing from/to your file |
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handles. |
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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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=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> specifies after how many seconds (fractional values are |
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supported) should the timer activate. C<cb> the callback to invoke in that |
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case. |
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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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undef $w; |
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Example 2: |
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# fire an event after 0.5 seconds, then roughly every second |
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my $w; |
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my $cb = sub { |
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# cancel the old timer while creating a new one |
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$w = AnyEvent->timer (after => 1, cb => $cb); |
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}; |
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# start the "loop" by creating the first watcher |
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$w = AnyEvent->timer (after => 0.5, cb => $cb); |
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=head3 TIMING ISSUES |
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There are two ways to handle timers: based on real time (relative, "fire |
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in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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o'clock"). |
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While most event loops expect timers to specified in a relative way, they use |
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absolute time internally. This makes a difference when your clock "jumps", |
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for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to |
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2008-01-01, a watcher that you created to fire "after" a second might actually take |
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six years to finally fire. |
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AnyEvent cannot compensate for this. The only event loop that is conscious |
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about these issues is L<EV>, which offers both relative (ev_timer) and |
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absolute (ev_periodic) timers. |
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AnyEvent always prefers relative timers, if available, matching the |
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AnyEvent API. |
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=head2 SIGNAL WATCHERS |
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You can watch for signals using a signal watcher, C<signal> is the signal |
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I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
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be invoked whenever a signal occurs. |
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Multiple signals occurances can be clumped together into one callback |
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invocation, and callback invocation will be synchronous. synchronous means |
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that it might take a while until the signal gets handled by the process, |
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but it is guarenteed not to interrupt any other callbacks. |
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The main advantage of using these watchers is that you can share a signal |
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between multiple watchers. |
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This watcher 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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=head2 CHILD PROCESS WATCHERS |
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You can also watch on a child process exit and catch its exit status. |
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The child process is specified by the C<pid> argument (if set to C<0>, it |
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watches for any child process exit). The watcher will trigger as often |
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as status change for the child are received. This works by installing a |
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signal handler for C<SIGCHLD>. The callback will be called with the pid |
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and exit status (as returned by waitpid). |
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Example: wait for pid 1333 |
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my $w = AnyEvent->child ( |
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pid => 1333, |
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cb => sub { |
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my ($pid, $status) = @_; |
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warn "pid $pid exited with status $status"; |
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}, |
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); |
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=head2 CONDITION VARIABLES |
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Condition variables can be created by calling the C<< AnyEvent->condvar >> |
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method without any arguments. |
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A condition variable waits for a condition - precisely that the C<< |
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->broadcast >> method has been called. |
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They are very useful to signal that a condition has been fulfilled, for |
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example, if you write a module that does asynchronous http requests, |
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then a condition variable would be the ideal candidate to signal the |
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availability of results. |
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You can also use condition variables to block your main program until |
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an event occurs - for example, you could C<< ->wait >> in your main |
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program until the user clicks the Quit button in your app, which would C<< |
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->broadcast >> the "quit" event. |
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Note that condition variables recurse into the event loop - if you have |
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two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
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lose. Therefore, condition variables are good to export to your caller, but |
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you should avoid making a blocking wait yourself, at least in callbacks, |
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as this asks for trouble. |
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This object has two methods: |
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=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 to stay interactive), so I<if you are |
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using this from a module, never require a blocking wait>, but let the |
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caller decide whether 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 L<AnyEvent::Impl::CoroEV> and |
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L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
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from different coroutines, however). |
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=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 (eventually) return after this method has been |
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called. If nobody is waiting the broadcast will be remembered.. |
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=back |
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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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# in this case, we simply use a timer: |
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my $w = AnyEvent->timer ( |
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after => 1, |
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cb => sub { $result_ready->broadcast }, |
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); |
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# this "blocks" (while handling events) till the watcher |
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# calls broadcast |
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$result_ready->wait; |
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=head1 GLOBAL VARIABLES AND FUNCTIONS |
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=over 4 |
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=item $AnyEvent::MODEL |
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Contains C<undef> until the first watcher is being created. Then it |
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contains the event model that is being used, which is the name of the |
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Perl class implementing the model. This class is usually one of the |
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C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
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AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
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The known classes so far are: |
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AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
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AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
358 |
root |
1.33 |
AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
359 |
root |
1.29 |
AnyEvent::Impl::Event based on Event, also second best choice :) |
360 |
root |
1.48 |
AnyEvent::Impl::Glib based on Glib, third-best choice. |
361 |
root |
1.16 |
AnyEvent::Impl::Tk based on Tk, very bad choice. |
362 |
root |
1.48 |
AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
363 |
root |
1.16 |
|
364 |
root |
1.19 |
=item AnyEvent::detect |
365 |
|
|
|
366 |
root |
1.53 |
Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
367 |
|
|
if necessary. You should only call this function right before you would |
368 |
|
|
have created an AnyEvent watcher anyway, that is, as late as possible at |
369 |
|
|
runtime. |
370 |
root |
1.19 |
|
371 |
root |
1.16 |
=back |
372 |
|
|
|
373 |
root |
1.14 |
=head1 WHAT TO DO IN A MODULE |
374 |
|
|
|
375 |
root |
1.53 |
As a module author, you should C<use AnyEvent> and call AnyEvent methods |
376 |
root |
1.14 |
freely, but you should not load a specific event module or rely on it. |
377 |
|
|
|
378 |
root |
1.53 |
Be careful when you create watchers in the module body - AnyEvent will |
379 |
root |
1.14 |
decide which event module to use as soon as the first method is called, so |
380 |
|
|
by calling AnyEvent in your module body you force the user of your module |
381 |
|
|
to load the event module first. |
382 |
|
|
|
383 |
root |
1.53 |
Never call C<< ->wait >> on a condition variable unless you I<know> that |
384 |
|
|
the C<< ->broadcast >> method has been called on it already. This is |
385 |
|
|
because it will stall the whole program, and the whole point of using |
386 |
|
|
events is to stay interactive. |
387 |
|
|
|
388 |
|
|
It is fine, however, to call C<< ->wait >> when the user of your module |
389 |
|
|
requests it (i.e. if you create a http request object ad have a method |
390 |
|
|
called C<results> that returns the results, it should call C<< ->wait >> |
391 |
|
|
freely, as the user of your module knows what she is doing. always). |
392 |
|
|
|
393 |
root |
1.14 |
=head1 WHAT TO DO IN THE MAIN PROGRAM |
394 |
|
|
|
395 |
|
|
There will always be a single main program - the only place that should |
396 |
|
|
dictate which event model to use. |
397 |
|
|
|
398 |
|
|
If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
399 |
root |
1.53 |
do anything special (it does not need to be event-based) and let AnyEvent |
400 |
|
|
decide which implementation to chose if some module relies on it. |
401 |
root |
1.14 |
|
402 |
root |
1.53 |
If the main program relies on a specific event model. For example, in |
403 |
|
|
Gtk2 programs you have to rely on the Glib module. You should load the |
404 |
|
|
event module before loading AnyEvent or any module that uses it: generally |
405 |
|
|
speaking, you should load it as early as possible. The reason is that |
406 |
|
|
modules might create watchers when they are loaded, and AnyEvent will |
407 |
|
|
decide on the event model to use as soon as it creates watchers, and it |
408 |
|
|
might chose the wrong one unless you load the correct one yourself. |
409 |
root |
1.14 |
|
410 |
|
|
You can chose to use a rather inefficient pure-perl implementation by |
411 |
root |
1.53 |
loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
412 |
|
|
behaviour everywhere, but letting AnyEvent chose is generally better. |
413 |
root |
1.14 |
|
414 |
root |
1.1 |
=cut |
415 |
|
|
|
416 |
|
|
package AnyEvent; |
417 |
|
|
|
418 |
root |
1.2 |
no warnings; |
419 |
root |
1.19 |
use strict; |
420 |
root |
1.24 |
|
421 |
root |
1.1 |
use Carp; |
422 |
|
|
|
423 |
root |
1.54 |
our $VERSION = '3.12'; |
424 |
root |
1.2 |
our $MODEL; |
425 |
root |
1.1 |
|
426 |
root |
1.2 |
our $AUTOLOAD; |
427 |
|
|
our @ISA; |
428 |
root |
1.1 |
|
429 |
root |
1.7 |
our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
430 |
|
|
|
431 |
root |
1.8 |
our @REGISTRY; |
432 |
|
|
|
433 |
root |
1.1 |
my @models = ( |
434 |
root |
1.33 |
[Coro::EV:: => AnyEvent::Impl::CoroEV::], |
435 |
root |
1.50 |
[Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
436 |
root |
1.33 |
[EV:: => AnyEvent::Impl::EV::], |
437 |
root |
1.18 |
[Event:: => AnyEvent::Impl::Event::], |
438 |
|
|
[Glib:: => AnyEvent::Impl::Glib::], |
439 |
|
|
[Tk:: => AnyEvent::Impl::Tk::], |
440 |
|
|
[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
441 |
root |
1.1 |
); |
442 |
|
|
|
443 |
root |
1.19 |
our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
444 |
root |
1.3 |
|
445 |
root |
1.19 |
sub detect() { |
446 |
|
|
unless ($MODEL) { |
447 |
|
|
no strict 'refs'; |
448 |
root |
1.1 |
|
449 |
root |
1.2 |
# check for already loaded models |
450 |
root |
1.8 |
for (@REGISTRY, @models) { |
451 |
|
|
my ($package, $model) = @$_; |
452 |
root |
1.7 |
if (${"$package\::VERSION"} > 0) { |
453 |
root |
1.8 |
if (eval "require $model") { |
454 |
|
|
$MODEL = $model; |
455 |
|
|
warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
456 |
|
|
last; |
457 |
|
|
} |
458 |
root |
1.2 |
} |
459 |
root |
1.1 |
} |
460 |
|
|
|
461 |
root |
1.2 |
unless ($MODEL) { |
462 |
|
|
# try to load a model |
463 |
|
|
|
464 |
root |
1.8 |
for (@REGISTRY, @models) { |
465 |
|
|
my ($package, $model) = @$_; |
466 |
root |
1.21 |
if (eval "require $package" |
467 |
|
|
and ${"$package\::VERSION"} > 0 |
468 |
|
|
and eval "require $model") { |
469 |
root |
1.8 |
$MODEL = $model; |
470 |
|
|
warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
471 |
|
|
last; |
472 |
|
|
} |
473 |
root |
1.2 |
} |
474 |
|
|
|
475 |
|
|
$MODEL |
476 |
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."; |
477 |
root |
1.1 |
} |
478 |
root |
1.19 |
|
479 |
|
|
unshift @ISA, $MODEL; |
480 |
|
|
push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
481 |
root |
1.1 |
} |
482 |
|
|
|
483 |
root |
1.19 |
$MODEL |
484 |
|
|
} |
485 |
|
|
|
486 |
|
|
sub AUTOLOAD { |
487 |
|
|
(my $func = $AUTOLOAD) =~ s/.*://; |
488 |
|
|
|
489 |
|
|
$method{$func} |
490 |
|
|
or croak "$func: not a valid method for AnyEvent objects"; |
491 |
|
|
|
492 |
|
|
detect unless $MODEL; |
493 |
root |
1.2 |
|
494 |
|
|
my $class = shift; |
495 |
root |
1.18 |
$class->$func (@_); |
496 |
root |
1.1 |
} |
497 |
|
|
|
498 |
root |
1.19 |
package AnyEvent::Base; |
499 |
|
|
|
500 |
root |
1.20 |
# default implementation for ->condvar, ->wait, ->broadcast |
501 |
|
|
|
502 |
|
|
sub condvar { |
503 |
|
|
bless \my $flag, "AnyEvent::Base::CondVar" |
504 |
|
|
} |
505 |
|
|
|
506 |
|
|
sub AnyEvent::Base::CondVar::broadcast { |
507 |
|
|
${$_[0]}++; |
508 |
|
|
} |
509 |
|
|
|
510 |
|
|
sub AnyEvent::Base::CondVar::wait { |
511 |
|
|
AnyEvent->one_event while !${$_[0]}; |
512 |
|
|
} |
513 |
|
|
|
514 |
|
|
# default implementation for ->signal |
515 |
root |
1.19 |
|
516 |
|
|
our %SIG_CB; |
517 |
|
|
|
518 |
|
|
sub signal { |
519 |
|
|
my (undef, %arg) = @_; |
520 |
|
|
|
521 |
|
|
my $signal = uc $arg{signal} |
522 |
|
|
or Carp::croak "required option 'signal' is missing"; |
523 |
|
|
|
524 |
root |
1.31 |
$SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
525 |
root |
1.19 |
$SIG{$signal} ||= sub { |
526 |
root |
1.20 |
$_->() for values %{ $SIG_CB{$signal} || {} }; |
527 |
root |
1.19 |
}; |
528 |
|
|
|
529 |
root |
1.20 |
bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
530 |
root |
1.19 |
} |
531 |
|
|
|
532 |
|
|
sub AnyEvent::Base::Signal::DESTROY { |
533 |
|
|
my ($signal, $cb) = @{$_[0]}; |
534 |
|
|
|
535 |
|
|
delete $SIG_CB{$signal}{$cb}; |
536 |
|
|
|
537 |
|
|
$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
538 |
|
|
} |
539 |
|
|
|
540 |
root |
1.20 |
# default implementation for ->child |
541 |
|
|
|
542 |
|
|
our %PID_CB; |
543 |
|
|
our $CHLD_W; |
544 |
root |
1.37 |
our $CHLD_DELAY_W; |
545 |
root |
1.20 |
our $PID_IDLE; |
546 |
|
|
our $WNOHANG; |
547 |
|
|
|
548 |
|
|
sub _child_wait { |
549 |
root |
1.38 |
while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
550 |
root |
1.32 |
$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
551 |
|
|
(values %{ $PID_CB{0} || {} }); |
552 |
root |
1.20 |
} |
553 |
|
|
|
554 |
|
|
undef $PID_IDLE; |
555 |
|
|
} |
556 |
|
|
|
557 |
root |
1.37 |
sub _sigchld { |
558 |
|
|
# make sure we deliver these changes "synchronous" with the event loop. |
559 |
|
|
$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
560 |
|
|
undef $CHLD_DELAY_W; |
561 |
|
|
&_child_wait; |
562 |
|
|
}); |
563 |
|
|
} |
564 |
|
|
|
565 |
root |
1.20 |
sub child { |
566 |
|
|
my (undef, %arg) = @_; |
567 |
|
|
|
568 |
root |
1.31 |
defined (my $pid = $arg{pid} + 0) |
569 |
root |
1.20 |
or Carp::croak "required option 'pid' is missing"; |
570 |
|
|
|
571 |
|
|
$PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
572 |
|
|
|
573 |
|
|
unless ($WNOHANG) { |
574 |
|
|
$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
575 |
|
|
} |
576 |
|
|
|
577 |
root |
1.23 |
unless ($CHLD_W) { |
578 |
root |
1.37 |
$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
579 |
|
|
# child could be a zombie already, so make at least one round |
580 |
|
|
&_sigchld; |
581 |
root |
1.23 |
} |
582 |
root |
1.20 |
|
583 |
|
|
bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
584 |
|
|
} |
585 |
|
|
|
586 |
|
|
sub AnyEvent::Base::Child::DESTROY { |
587 |
|
|
my ($pid, $cb) = @{$_[0]}; |
588 |
|
|
|
589 |
|
|
delete $PID_CB{$pid}{$cb}; |
590 |
|
|
delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
591 |
|
|
|
592 |
|
|
undef $CHLD_W unless keys %PID_CB; |
593 |
|
|
} |
594 |
|
|
|
595 |
root |
1.8 |
=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
596 |
|
|
|
597 |
root |
1.53 |
This is an advanced topic that you do not normally need to use AnyEvent in |
598 |
|
|
a module. This section is only of use to event loop authors who want to |
599 |
|
|
provide AnyEvent compatibility. |
600 |
|
|
|
601 |
root |
1.8 |
If you need to support another event library which isn't directly |
602 |
|
|
supported by AnyEvent, you can supply your own interface to it by |
603 |
root |
1.11 |
pushing, before the first watcher gets created, the package name of |
604 |
root |
1.8 |
the event module and the package name of the interface to use onto |
605 |
|
|
C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
606 |
root |
1.53 |
AnyEvent, so it is reasonably cheap. |
607 |
root |
1.8 |
|
608 |
|
|
Example: |
609 |
|
|
|
610 |
|
|
push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
611 |
|
|
|
612 |
root |
1.12 |
This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
613 |
root |
1.53 |
package/class when it finds the C<urxvt> package/module is already loaded. |
614 |
|
|
|
615 |
|
|
When AnyEvent is loaded and asked to find a suitable event model, it |
616 |
|
|
will first check for the presence of urxvt by trying to C<use> the |
617 |
|
|
C<urxvt::anyevent> module. |
618 |
|
|
|
619 |
|
|
The class should provide implementations for all watcher types. See |
620 |
|
|
L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
621 |
|
|
and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
622 |
|
|
see the sources. |
623 |
|
|
|
624 |
|
|
If you don't provide C<signal> and C<child> watchers than AnyEvent will |
625 |
|
|
provide suitable (hopefully) replacements. |
626 |
|
|
|
627 |
|
|
The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
628 |
|
|
terminal emulator uses the above line as-is. An interface isn't included |
629 |
|
|
in AnyEvent because it doesn't make sense outside the embedded interpreter |
630 |
|
|
inside I<rxvt-unicode>, and it is updated and maintained as part of the |
631 |
root |
1.8 |
I<rxvt-unicode> distribution. |
632 |
|
|
|
633 |
root |
1.12 |
I<rxvt-unicode> also cheats a bit by not providing blocking access to |
634 |
|
|
condition variables: code blocking while waiting for a condition will |
635 |
|
|
C<die>. This still works with most modules/usages, and blocking calls must |
636 |
root |
1.53 |
not be done in an interactive application, so it makes sense. |
637 |
root |
1.12 |
|
638 |
root |
1.7 |
=head1 ENVIRONMENT VARIABLES |
639 |
|
|
|
640 |
|
|
The following environment variables are used by this module: |
641 |
|
|
|
642 |
root |
1.53 |
C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, cause AnyEvent to |
643 |
|
|
report to STDERR which event model it chooses. |
644 |
root |
1.7 |
|
645 |
root |
1.53 |
=head1 EXAMPLE PROGRAM |
646 |
root |
1.2 |
|
647 |
root |
1.53 |
The following program uses an IO watcher to read data from STDIN, a timer |
648 |
|
|
to display a message once per second, and a condition variable to quit the |
649 |
|
|
program when the user enters quit: |
650 |
root |
1.2 |
|
651 |
|
|
use AnyEvent; |
652 |
|
|
|
653 |
|
|
my $cv = AnyEvent->condvar; |
654 |
|
|
|
655 |
root |
1.53 |
my $io_watcher = AnyEvent->io ( |
656 |
|
|
fh => \*STDIN, |
657 |
|
|
poll => 'r', |
658 |
|
|
cb => sub { |
659 |
|
|
warn "io event <$_[0]>\n"; # will always output <r> |
660 |
|
|
chomp (my $input = <STDIN>); # read a line |
661 |
|
|
warn "read: $input\n"; # output what has been read |
662 |
|
|
$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
663 |
|
|
}, |
664 |
|
|
); |
665 |
root |
1.2 |
|
666 |
|
|
my $time_watcher; # can only be used once |
667 |
|
|
|
668 |
|
|
sub new_timer { |
669 |
|
|
$timer = AnyEvent->timer (after => 1, cb => sub { |
670 |
|
|
warn "timeout\n"; # print 'timeout' about every second |
671 |
|
|
&new_timer; # and restart the time |
672 |
|
|
}); |
673 |
|
|
} |
674 |
|
|
|
675 |
|
|
new_timer; # create first timer |
676 |
|
|
|
677 |
|
|
$cv->wait; # wait until user enters /^q/i |
678 |
|
|
|
679 |
root |
1.5 |
=head1 REAL-WORLD EXAMPLE |
680 |
|
|
|
681 |
|
|
Consider the L<Net::FCP> module. It features (among others) the following |
682 |
|
|
API calls, which are to freenet what HTTP GET requests are to http: |
683 |
|
|
|
684 |
|
|
my $data = $fcp->client_get ($url); # blocks |
685 |
|
|
|
686 |
|
|
my $transaction = $fcp->txn_client_get ($url); # does not block |
687 |
|
|
$transaction->cb ( sub { ... } ); # set optional result callback |
688 |
|
|
my $data = $transaction->result; # possibly blocks |
689 |
|
|
|
690 |
|
|
The C<client_get> method works like C<LWP::Simple::get>: it requests the |
691 |
|
|
given URL and waits till the data has arrived. It is defined to be: |
692 |
|
|
|
693 |
|
|
sub client_get { $_[0]->txn_client_get ($_[1])->result } |
694 |
|
|
|
695 |
|
|
And in fact is automatically generated. This is the blocking API of |
696 |
|
|
L<Net::FCP>, and it works as simple as in any other, similar, module. |
697 |
|
|
|
698 |
|
|
More complicated is C<txn_client_get>: It only creates a transaction |
699 |
|
|
(completion, result, ...) object and initiates the transaction. |
700 |
|
|
|
701 |
|
|
my $txn = bless { }, Net::FCP::Txn::; |
702 |
|
|
|
703 |
|
|
It also creates a condition variable that is used to signal the completion |
704 |
|
|
of the request: |
705 |
|
|
|
706 |
|
|
$txn->{finished} = AnyAvent->condvar; |
707 |
|
|
|
708 |
|
|
It then creates a socket in non-blocking mode. |
709 |
|
|
|
710 |
|
|
socket $txn->{fh}, ...; |
711 |
|
|
fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
712 |
|
|
connect $txn->{fh}, ... |
713 |
|
|
and !$!{EWOULDBLOCK} |
714 |
|
|
and !$!{EINPROGRESS} |
715 |
|
|
and Carp::croak "unable to connect: $!\n"; |
716 |
|
|
|
717 |
root |
1.6 |
Then it creates a write-watcher which gets called whenever an error occurs |
718 |
root |
1.5 |
or the connection succeeds: |
719 |
|
|
|
720 |
|
|
$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
721 |
|
|
|
722 |
|
|
And returns this transaction object. The C<fh_ready_w> callback gets |
723 |
|
|
called as soon as the event loop detects that the socket is ready for |
724 |
|
|
writing. |
725 |
|
|
|
726 |
|
|
The C<fh_ready_w> method makes the socket blocking again, writes the |
727 |
|
|
request data and replaces the watcher by a read watcher (waiting for reply |
728 |
|
|
data). The actual code is more complicated, but that doesn't matter for |
729 |
|
|
this example: |
730 |
|
|
|
731 |
|
|
fcntl $txn->{fh}, F_SETFL, 0; |
732 |
|
|
syswrite $txn->{fh}, $txn->{request} |
733 |
|
|
or die "connection or write error"; |
734 |
|
|
$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
735 |
|
|
|
736 |
|
|
Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
737 |
|
|
result and signals any possible waiters that the request ahs finished: |
738 |
|
|
|
739 |
|
|
sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
740 |
|
|
|
741 |
|
|
if (end-of-file or data complete) { |
742 |
|
|
$txn->{result} = $txn->{buf}; |
743 |
|
|
$txn->{finished}->broadcast; |
744 |
root |
1.6 |
$txb->{cb}->($txn) of $txn->{cb}; # also call callback |
745 |
root |
1.5 |
} |
746 |
|
|
|
747 |
|
|
The C<result> method, finally, just waits for the finished signal (if the |
748 |
|
|
request was already finished, it doesn't wait, of course, and returns the |
749 |
|
|
data: |
750 |
|
|
|
751 |
|
|
$txn->{finished}->wait; |
752 |
root |
1.6 |
return $txn->{result}; |
753 |
root |
1.5 |
|
754 |
|
|
The actual code goes further and collects all errors (C<die>s, exceptions) |
755 |
|
|
that occured during request processing. The C<result> method detects |
756 |
root |
1.52 |
whether an exception as thrown (it is stored inside the $txn object) |
757 |
root |
1.5 |
and just throws the exception, which means connection errors and other |
758 |
|
|
problems get reported tot he code that tries to use the result, not in a |
759 |
|
|
random callback. |
760 |
|
|
|
761 |
|
|
All of this enables the following usage styles: |
762 |
|
|
|
763 |
|
|
1. Blocking: |
764 |
|
|
|
765 |
|
|
my $data = $fcp->client_get ($url); |
766 |
|
|
|
767 |
root |
1.49 |
2. Blocking, but running in parallel: |
768 |
root |
1.5 |
|
769 |
|
|
my @datas = map $_->result, |
770 |
|
|
map $fcp->txn_client_get ($_), |
771 |
|
|
@urls; |
772 |
|
|
|
773 |
|
|
Both blocking examples work without the module user having to know |
774 |
|
|
anything about events. |
775 |
|
|
|
776 |
root |
1.49 |
3a. Event-based in a main program, using any supported event module: |
777 |
root |
1.5 |
|
778 |
root |
1.49 |
use EV; |
779 |
root |
1.5 |
|
780 |
|
|
$fcp->txn_client_get ($url)->cb (sub { |
781 |
|
|
my $txn = shift; |
782 |
|
|
my $data = $txn->result; |
783 |
|
|
... |
784 |
|
|
}); |
785 |
|
|
|
786 |
root |
1.49 |
EV::loop; |
787 |
root |
1.5 |
|
788 |
|
|
3b. The module user could use AnyEvent, too: |
789 |
|
|
|
790 |
|
|
use AnyEvent; |
791 |
|
|
|
792 |
|
|
my $quit = AnyEvent->condvar; |
793 |
|
|
|
794 |
|
|
$fcp->txn_client_get ($url)->cb (sub { |
795 |
|
|
... |
796 |
|
|
$quit->broadcast; |
797 |
|
|
}); |
798 |
|
|
|
799 |
|
|
$quit->wait; |
800 |
|
|
|
801 |
root |
1.2 |
=head1 SEE ALSO |
802 |
|
|
|
803 |
root |
1.49 |
Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
804 |
|
|
L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
805 |
root |
1.5 |
|
806 |
root |
1.49 |
Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
807 |
|
|
L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
808 |
|
|
L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
809 |
root |
1.5 |
|
810 |
root |
1.49 |
Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
811 |
root |
1.2 |
|
812 |
root |
1.54 |
=head1 AUTHOR |
813 |
|
|
|
814 |
|
|
Marc Lehmann <schmorp@schmorp.de> |
815 |
|
|
http://home.schmorp.de/ |
816 |
root |
1.2 |
|
817 |
|
|
=cut |
818 |
|
|
|
819 |
|
|
1 |
820 |
root |
1.1 |
|