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=head1 NAME |
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AnyEvent - provide framework for multiple event loops |
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EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
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=head1 SYNOPSIS |
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use AnyEvent; |
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|
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# file descriptor readable |
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my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
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|
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# one-shot or repeating timers |
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my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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print AnyEvent->now; # prints current event loop time |
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print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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# POSIX signal |
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my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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|
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# child process exit |
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my $w = AnyEvent->child (pid => $pid, cb => sub { |
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my ($pid, $status) = @_; |
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... |
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}); |
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# called when event loop idle (if applicable) |
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my $w = AnyEvent->idle (cb => sub { ... }); |
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my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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$w->send; # wake up current and all future recv's |
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$w->recv; # enters "main loop" till $condvar gets ->send |
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# use a condvar in callback mode: |
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$w->cb (sub { $_[0]->recv }); |
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=head1 INTRODUCTION/TUTORIAL |
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This manpage is mainly a reference manual. If you are interested |
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in a tutorial or some gentle introduction, have a look at the |
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L<AnyEvent::Intro> manpage. |
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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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cannot change this, but it can hide the differences between those event |
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loops. |
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|
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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 they are simply incompatible to everything |
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that isn't them. What's worse, all the potential users of your |
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module are I<also> forced to use the same event loop you use. |
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|
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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 IO::Async, as long as those |
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use one of the supported event loops. It is trivial to add new event loops |
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to AnyEvent, too, so it is future-proof). |
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1.41 |
|
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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 enormous amount of code and strict rules you have to |
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1.53 |
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, AnyEvent comes with a big (and fully optional!) toolbox |
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of useful functionality, such as an asynchronous DNS resolver, 100% |
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non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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such as Windows) and lots of real-world knowledge and workarounds for |
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platform bugs and differences. |
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Now, if you I<do 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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1.43 |
|
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1.1 |
=head1 DESCRIPTION |
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1.2 |
L<AnyEvent> provides an identical interface to multiple event loops. This |
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1.13 |
allows module authors to utilise an event loop without forcing module |
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1.2 |
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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1.2 |
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<EV>, |
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L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
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1.61 |
L<POE>. The first one found is used. If none are found, the module tries |
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1.81 |
to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
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1.61 |
adaptor should always succeed) in the order given. The first one that can |
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be successfully loaded will be used. If, after this, still none could be |
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found, AnyEvent will fall back to a pure-perl event loop, which is not |
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very efficient, but should work everywhere. |
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1.14 |
|
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Because AnyEvent first checks for modules that are already loaded, loading |
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1.53 |
an event model explicitly before first using AnyEvent will likely make |
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1.14 |
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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1.142 |
explicitly and enjoy the high availability of that event loop :) |
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|
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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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1.128 |
the callback to call, the file handle to watch, etc. |
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1.14 |
|
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These watchers are normal Perl objects with normal Perl lifetime. After |
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1.53 |
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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Note that B<callbacks must not permanently change global variables> |
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potentially in use by the event loop (such as C<$_> or C<$[>) and that B<< |
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callbacks must not C<die> >>. The former is good programming practise in |
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Perl and the latter stems from the fact that exception handling differs |
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widely between event loops. |
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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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|
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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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1.78 |
=head2 I/O WATCHERS |
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|
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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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|
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C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch |
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for events (AnyEvent might or might not keep a reference to this file |
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handle). Note that only file handles pointing to things for which |
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non-blocking operation makes sense are allowed. This includes sockets, |
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most character devices, pipes, fifos and so on, but not for example files |
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or block devices. |
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C<poll> must be a string that is either C<r> or C<w>, which creates a |
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watcher waiting for "r"eadable or "w"ritable events, respectively. |
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C<cb> is the callback to invoke each time the file handle becomes ready. |
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|
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Although the callback might get passed parameters, their value and |
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presence is undefined and you cannot rely on them. Portable AnyEvent |
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callbacks cannot use arguments passed to I/O watcher callbacks. |
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1.82 |
The I/O watcher might use the underlying file descriptor or a copy of it. |
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You must not close a file handle as long as any watcher is active on the |
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underlying file descriptor. |
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|
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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: wait for readability of STDIN, then read a line and disable the |
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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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1.14 |
|
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1.19 |
You can create a time watcher by calling the C<< AnyEvent->timer >> |
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1.14 |
method with the following mandatory arguments: |
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1.53 |
C<after> specifies after how many seconds (fractional values are |
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1.85 |
supported) the callback should be invoked. C<cb> is the callback to invoke |
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in that case. |
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Although the callback might get passed parameters, their value and |
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presence is undefined and you cannot rely on them. Portable AnyEvent |
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callbacks cannot use arguments passed to time watcher callbacks. |
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1.14 |
|
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1.164 |
The callback will normally be invoked once only. If you specify another |
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parameter, C<interval>, as a strictly positive number (> 0), then the |
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callback will be invoked regularly at that interval (in fractional |
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seconds) after the first invocation. If C<interval> is specified with a |
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false value, then it is treated as if it were missing. |
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1.164 |
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The callback will be rescheduled before invoking the callback, but no |
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attempt is done to avoid timer drift in most backends, so the interval is |
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only approximate. |
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1.14 |
|
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1.164 |
Example: fire an event after 7.7 seconds. |
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1.14 |
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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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|
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Example 2: fire an event after 0.5 seconds, then roughly every second. |
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1.53 |
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1.164 |
my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
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warn "timeout\n"; |
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1.53 |
}; |
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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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1.58 |
While most event loops expect timers to specified in a relative way, they |
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use absolute time internally. This makes a difference when your clock |
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"jumps", for example, when ntp decides to set your clock backwards from |
260 |
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the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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fire "after" a second might actually take six years to finally fire. |
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1.53 |
|
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AnyEvent cannot compensate for this. The only event loop that is conscious |
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1.58 |
about these issues is L<EV>, which offers both relative (ev_timer, based |
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on true relative time) and absolute (ev_periodic, based on wallclock time) |
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timers. |
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AnyEvent always prefers relative timers, if available, matching the |
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AnyEvent API. |
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1.143 |
AnyEvent has two additional methods that return the "current time": |
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=over 4 |
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=item AnyEvent->time |
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This returns the "current wallclock time" as a fractional number of |
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seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time> |
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return, and the result is guaranteed to be compatible with those). |
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1.144 |
It progresses independently of any event loop processing, i.e. each call |
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will check the system clock, which usually gets updated frequently. |
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|
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=item AnyEvent->now |
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This also returns the "current wallclock time", but unlike C<time>, above, |
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this value might change only once per event loop iteration, depending on |
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the event loop (most return the same time as C<time>, above). This is the |
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1.144 |
time that AnyEvent's timers get scheduled against. |
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I<In almost all cases (in all cases if you don't care), this is the |
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function to call when you want to know the current time.> |
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This function is also often faster then C<< AnyEvent->time >>, and |
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thus the preferred method if you want some timestamp (for example, |
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L<AnyEvent::Handle> uses this to update it's activity timeouts). |
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The rest of this section is only of relevance if you try to be very exact |
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with your timing, you can skip it without bad conscience. |
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1.143 |
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For a practical example of when these times differ, consider L<Event::Lib> |
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and L<EV> and the following set-up: |
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The event loop is running and has just invoked one of your callback at |
305 |
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time=500 (assume no other callbacks delay processing). In your callback, |
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you wait a second by executing C<sleep 1> (blocking the process for a |
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second) and then (at time=501) you create a relative timer that fires |
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after three seconds. |
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With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will |
311 |
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both return C<501>, because that is the current time, and the timer will |
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be scheduled to fire at time=504 (C<501> + C<3>). |
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1.144 |
With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current |
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time), but C<< AnyEvent->now >> returns C<500>, as that is the time the |
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last event processing phase started. With L<EV>, your timer gets scheduled |
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to run at time=503 (C<500> + C<3>). |
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In one sense, L<Event::Lib> is more exact, as it uses the current time |
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regardless of any delays introduced by event processing. However, most |
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callbacks do not expect large delays in processing, so this causes a |
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higher drift (and a lot more system calls to get the current time). |
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|
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In another sense, L<EV> is more exact, as your timer will be scheduled at |
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the same time, regardless of how long event processing actually took. |
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In either case, if you care (and in most cases, you don't), then you |
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can get whatever behaviour you want with any event loop, by taking the |
329 |
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difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into |
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account. |
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1.205 |
=item AnyEvent->now_update |
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Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache |
335 |
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the current time for each loop iteration (see the discussion of L<< |
336 |
|
|
AnyEvent->now >>, above). |
337 |
|
|
|
338 |
|
|
When a callback runs for a long time (or when the process sleeps), then |
339 |
|
|
this "current" time will differ substantially from the real time, which |
340 |
|
|
might affect timers and time-outs. |
341 |
|
|
|
342 |
|
|
When this is the case, you can call this method, which will update the |
343 |
|
|
event loop's idea of "current time". |
344 |
|
|
|
345 |
|
|
Note that updating the time I<might> cause some events to be handled. |
346 |
|
|
|
347 |
root |
1.143 |
=back |
348 |
|
|
|
349 |
root |
1.53 |
=head2 SIGNAL WATCHERS |
350 |
root |
1.14 |
|
351 |
root |
1.53 |
You can watch for signals using a signal watcher, C<signal> is the signal |
352 |
root |
1.167 |
I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl |
353 |
|
|
callback to be invoked whenever a signal occurs. |
354 |
root |
1.53 |
|
355 |
root |
1.85 |
Although the callback might get passed parameters, their value and |
356 |
|
|
presence is undefined and you cannot rely on them. Portable AnyEvent |
357 |
|
|
callbacks cannot use arguments passed to signal watcher callbacks. |
358 |
|
|
|
359 |
elmex |
1.129 |
Multiple signal occurrences can be clumped together into one callback |
360 |
|
|
invocation, and callback invocation will be synchronous. Synchronous means |
361 |
root |
1.53 |
that it might take a while until the signal gets handled by the process, |
362 |
elmex |
1.129 |
but it is guaranteed not to interrupt any other callbacks. |
363 |
root |
1.53 |
|
364 |
|
|
The main advantage of using these watchers is that you can share a signal |
365 |
|
|
between multiple watchers. |
366 |
|
|
|
367 |
|
|
This watcher might use C<%SIG>, so programs overwriting those signals |
368 |
|
|
directly will likely not work correctly. |
369 |
|
|
|
370 |
|
|
Example: exit on SIGINT |
371 |
|
|
|
372 |
|
|
my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
373 |
|
|
|
374 |
|
|
=head2 CHILD PROCESS WATCHERS |
375 |
|
|
|
376 |
|
|
You can also watch on a child process exit and catch its exit status. |
377 |
|
|
|
378 |
|
|
The child process is specified by the C<pid> argument (if set to C<0>, it |
379 |
root |
1.181 |
watches for any child process exit). The watcher will triggered only when |
380 |
|
|
the child process has finished and an exit status is available, not on |
381 |
|
|
any trace events (stopped/continued). |
382 |
|
|
|
383 |
|
|
The callback will be called with the pid and exit status (as returned by |
384 |
|
|
waitpid), so unlike other watcher types, you I<can> rely on child watcher |
385 |
|
|
callback arguments. |
386 |
|
|
|
387 |
|
|
This watcher type works by installing a signal handler for C<SIGCHLD>, |
388 |
|
|
and since it cannot be shared, nothing else should use SIGCHLD or reap |
389 |
|
|
random child processes (waiting for specific child processes, e.g. inside |
390 |
|
|
C<system>, is just fine). |
391 |
root |
1.53 |
|
392 |
root |
1.82 |
There is a slight catch to child watchers, however: you usually start them |
393 |
|
|
I<after> the child process was created, and this means the process could |
394 |
|
|
have exited already (and no SIGCHLD will be sent anymore). |
395 |
|
|
|
396 |
|
|
Not all event models handle this correctly (POE doesn't), but even for |
397 |
|
|
event models that I<do> handle this correctly, they usually need to be |
398 |
|
|
loaded before the process exits (i.e. before you fork in the first place). |
399 |
|
|
|
400 |
|
|
This means you cannot create a child watcher as the very first thing in an |
401 |
|
|
AnyEvent program, you I<have> to create at least one watcher before you |
402 |
|
|
C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
403 |
|
|
|
404 |
|
|
Example: fork a process and wait for it |
405 |
|
|
|
406 |
root |
1.151 |
my $done = AnyEvent->condvar; |
407 |
|
|
|
408 |
|
|
my $pid = fork or exit 5; |
409 |
|
|
|
410 |
|
|
my $w = AnyEvent->child ( |
411 |
|
|
pid => $pid, |
412 |
|
|
cb => sub { |
413 |
|
|
my ($pid, $status) = @_; |
414 |
|
|
warn "pid $pid exited with status $status"; |
415 |
|
|
$done->send; |
416 |
|
|
}, |
417 |
|
|
); |
418 |
|
|
|
419 |
|
|
# do something else, then wait for process exit |
420 |
|
|
$done->recv; |
421 |
root |
1.82 |
|
422 |
root |
1.207 |
=head2 IDLE WATCHERS |
423 |
|
|
|
424 |
|
|
Sometimes there is a need to do something, but it is not so important |
425 |
|
|
to do it instantly, but only when there is nothing better to do. This |
426 |
|
|
"nothing better to do" is usually defined to be "no other events need |
427 |
|
|
attention by the event loop". |
428 |
|
|
|
429 |
|
|
Idle watchers ideally get invoked when the event loop has nothing |
430 |
|
|
better to do, just before it would block the process to wait for new |
431 |
|
|
events. Instead of blocking, the idle watcher is invoked. |
432 |
|
|
|
433 |
|
|
Most event loops unfortunately do not really support idle watchers (only |
434 |
|
|
EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
435 |
|
|
will simply call the callback "from time to time". |
436 |
|
|
|
437 |
|
|
Example: read lines from STDIN, but only process them when the |
438 |
|
|
program is otherwise idle: |
439 |
|
|
|
440 |
|
|
my @lines; # read data |
441 |
|
|
my $idle_w; |
442 |
|
|
my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
443 |
|
|
push @lines, scalar <STDIN>; |
444 |
|
|
|
445 |
|
|
# start an idle watcher, if not already done |
446 |
|
|
$idle_w ||= AnyEvent->idle (cb => sub { |
447 |
|
|
# handle only one line, when there are lines left |
448 |
|
|
if (my $line = shift @lines) { |
449 |
|
|
print "handled when idle: $line"; |
450 |
|
|
} else { |
451 |
|
|
# otherwise disable the idle watcher again |
452 |
|
|
undef $idle_w; |
453 |
|
|
} |
454 |
|
|
}); |
455 |
|
|
}); |
456 |
|
|
|
457 |
root |
1.53 |
=head2 CONDITION VARIABLES |
458 |
|
|
|
459 |
root |
1.105 |
If you are familiar with some event loops you will know that all of them |
460 |
|
|
require you to run some blocking "loop", "run" or similar function that |
461 |
|
|
will actively watch for new events and call your callbacks. |
462 |
|
|
|
463 |
|
|
AnyEvent is different, it expects somebody else to run the event loop and |
464 |
|
|
will only block when necessary (usually when told by the user). |
465 |
|
|
|
466 |
|
|
The instrument to do that is called a "condition variable", so called |
467 |
|
|
because they represent a condition that must become true. |
468 |
|
|
|
469 |
|
|
Condition variables can be created by calling the C<< AnyEvent->condvar |
470 |
|
|
>> method, usually without arguments. The only argument pair allowed is |
471 |
root |
1.173 |
|
472 |
root |
1.105 |
C<cb>, which specifies a callback to be called when the condition variable |
473 |
root |
1.173 |
becomes true, with the condition variable as the first argument (but not |
474 |
|
|
the results). |
475 |
root |
1.105 |
|
476 |
elmex |
1.129 |
After creation, the condition variable is "false" until it becomes "true" |
477 |
root |
1.131 |
by calling the C<send> method (or calling the condition variable as if it |
478 |
root |
1.135 |
were a callback, read about the caveats in the description for the C<< |
479 |
|
|
->send >> method). |
480 |
root |
1.105 |
|
481 |
|
|
Condition variables are similar to callbacks, except that you can |
482 |
|
|
optionally wait for them. They can also be called merge points - points |
483 |
elmex |
1.129 |
in time where multiple outstanding events have been processed. And yet |
484 |
|
|
another way to call them is transactions - each condition variable can be |
485 |
root |
1.105 |
used to represent a transaction, which finishes at some point and delivers |
486 |
|
|
a result. |
487 |
root |
1.14 |
|
488 |
root |
1.105 |
Condition variables are very useful to signal that something has finished, |
489 |
|
|
for example, if you write a module that does asynchronous http requests, |
490 |
root |
1.53 |
then a condition variable would be the ideal candidate to signal the |
491 |
root |
1.105 |
availability of results. The user can either act when the callback is |
492 |
root |
1.114 |
called or can synchronously C<< ->recv >> for the results. |
493 |
root |
1.53 |
|
494 |
root |
1.105 |
You can also use them to simulate traditional event loops - for example, |
495 |
|
|
you can block your main program until an event occurs - for example, you |
496 |
root |
1.114 |
could C<< ->recv >> in your main program until the user clicks the Quit |
497 |
root |
1.106 |
button of your app, which would C<< ->send >> the "quit" event. |
498 |
root |
1.53 |
|
499 |
|
|
Note that condition variables recurse into the event loop - if you have |
500 |
elmex |
1.129 |
two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
501 |
root |
1.53 |
lose. Therefore, condition variables are good to export to your caller, but |
502 |
|
|
you should avoid making a blocking wait yourself, at least in callbacks, |
503 |
|
|
as this asks for trouble. |
504 |
root |
1.41 |
|
505 |
root |
1.105 |
Condition variables are represented by hash refs in perl, and the keys |
506 |
|
|
used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
507 |
|
|
easy (it is often useful to build your own transaction class on top of |
508 |
|
|
AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
509 |
|
|
it's C<new> method in your own C<new> method. |
510 |
|
|
|
511 |
|
|
There are two "sides" to a condition variable - the "producer side" which |
512 |
root |
1.106 |
eventually calls C<< -> send >>, and the "consumer side", which waits |
513 |
|
|
for the send to occur. |
514 |
root |
1.105 |
|
515 |
root |
1.131 |
Example: wait for a timer. |
516 |
root |
1.105 |
|
517 |
|
|
# wait till the result is ready |
518 |
|
|
my $result_ready = AnyEvent->condvar; |
519 |
|
|
|
520 |
|
|
# do something such as adding a timer |
521 |
root |
1.106 |
# or socket watcher the calls $result_ready->send |
522 |
root |
1.105 |
# when the "result" is ready. |
523 |
|
|
# in this case, we simply use a timer: |
524 |
|
|
my $w = AnyEvent->timer ( |
525 |
|
|
after => 1, |
526 |
root |
1.106 |
cb => sub { $result_ready->send }, |
527 |
root |
1.105 |
); |
528 |
|
|
|
529 |
|
|
# this "blocks" (while handling events) till the callback |
530 |
root |
1.106 |
# calls send |
531 |
root |
1.114 |
$result_ready->recv; |
532 |
root |
1.105 |
|
533 |
root |
1.131 |
Example: wait for a timer, but take advantage of the fact that |
534 |
|
|
condition variables are also code references. |
535 |
|
|
|
536 |
|
|
my $done = AnyEvent->condvar; |
537 |
|
|
my $delay = AnyEvent->timer (after => 5, cb => $done); |
538 |
|
|
$done->recv; |
539 |
|
|
|
540 |
root |
1.173 |
Example: Imagine an API that returns a condvar and doesn't support |
541 |
|
|
callbacks. This is how you make a synchronous call, for example from |
542 |
|
|
the main program: |
543 |
|
|
|
544 |
|
|
use AnyEvent::CouchDB; |
545 |
|
|
|
546 |
|
|
... |
547 |
|
|
|
548 |
|
|
my @info = $couchdb->info->recv; |
549 |
|
|
|
550 |
|
|
And this is how you would just ste a callback to be called whenever the |
551 |
|
|
results are available: |
552 |
|
|
|
553 |
|
|
$couchdb->info->cb (sub { |
554 |
|
|
my @info = $_[0]->recv; |
555 |
|
|
}); |
556 |
|
|
|
557 |
root |
1.105 |
=head3 METHODS FOR PRODUCERS |
558 |
|
|
|
559 |
|
|
These methods should only be used by the producing side, i.e. the |
560 |
root |
1.106 |
code/module that eventually sends the signal. Note that it is also |
561 |
root |
1.105 |
the producer side which creates the condvar in most cases, but it isn't |
562 |
|
|
uncommon for the consumer to create it as well. |
563 |
root |
1.2 |
|
564 |
root |
1.1 |
=over 4 |
565 |
|
|
|
566 |
root |
1.106 |
=item $cv->send (...) |
567 |
root |
1.105 |
|
568 |
root |
1.114 |
Flag the condition as ready - a running C<< ->recv >> and all further |
569 |
|
|
calls to C<recv> will (eventually) return after this method has been |
570 |
root |
1.106 |
called. If nobody is waiting the send will be remembered. |
571 |
root |
1.105 |
|
572 |
|
|
If a callback has been set on the condition variable, it is called |
573 |
root |
1.106 |
immediately from within send. |
574 |
root |
1.105 |
|
575 |
root |
1.106 |
Any arguments passed to the C<send> call will be returned by all |
576 |
root |
1.114 |
future C<< ->recv >> calls. |
577 |
root |
1.105 |
|
578 |
root |
1.135 |
Condition variables are overloaded so one can call them directly |
579 |
|
|
(as a code reference). Calling them directly is the same as calling |
580 |
|
|
C<send>. Note, however, that many C-based event loops do not handle |
581 |
|
|
overloading, so as tempting as it may be, passing a condition variable |
582 |
|
|
instead of a callback does not work. Both the pure perl and EV loops |
583 |
|
|
support overloading, however, as well as all functions that use perl to |
584 |
|
|
invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for |
585 |
|
|
example). |
586 |
root |
1.131 |
|
587 |
root |
1.105 |
=item $cv->croak ($error) |
588 |
|
|
|
589 |
root |
1.114 |
Similar to send, but causes all call's to C<< ->recv >> to invoke |
590 |
root |
1.105 |
C<Carp::croak> with the given error message/object/scalar. |
591 |
|
|
|
592 |
|
|
This can be used to signal any errors to the condition variable |
593 |
|
|
user/consumer. |
594 |
|
|
|
595 |
|
|
=item $cv->begin ([group callback]) |
596 |
|
|
|
597 |
|
|
=item $cv->end |
598 |
|
|
|
599 |
root |
1.114 |
These two methods are EXPERIMENTAL and MIGHT CHANGE. |
600 |
|
|
|
601 |
root |
1.105 |
These two methods can be used to combine many transactions/events into |
602 |
|
|
one. For example, a function that pings many hosts in parallel might want |
603 |
|
|
to use a condition variable for the whole process. |
604 |
|
|
|
605 |
|
|
Every call to C<< ->begin >> will increment a counter, and every call to |
606 |
|
|
C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
607 |
|
|
>>, the (last) callback passed to C<begin> will be executed. That callback |
608 |
root |
1.106 |
is I<supposed> to call C<< ->send >>, but that is not required. If no |
609 |
|
|
callback was set, C<send> will be called without any arguments. |
610 |
root |
1.105 |
|
611 |
|
|
Let's clarify this with the ping example: |
612 |
|
|
|
613 |
|
|
my $cv = AnyEvent->condvar; |
614 |
|
|
|
615 |
|
|
my %result; |
616 |
root |
1.106 |
$cv->begin (sub { $cv->send (\%result) }); |
617 |
root |
1.105 |
|
618 |
|
|
for my $host (@list_of_hosts) { |
619 |
|
|
$cv->begin; |
620 |
|
|
ping_host_then_call_callback $host, sub { |
621 |
|
|
$result{$host} = ...; |
622 |
|
|
$cv->end; |
623 |
|
|
}; |
624 |
|
|
} |
625 |
|
|
|
626 |
|
|
$cv->end; |
627 |
|
|
|
628 |
|
|
This code fragment supposedly pings a number of hosts and calls |
629 |
root |
1.106 |
C<send> after results for all then have have been gathered - in any |
630 |
root |
1.105 |
order. To achieve this, the code issues a call to C<begin> when it starts |
631 |
|
|
each ping request and calls C<end> when it has received some result for |
632 |
|
|
it. Since C<begin> and C<end> only maintain a counter, the order in which |
633 |
|
|
results arrive is not relevant. |
634 |
|
|
|
635 |
|
|
There is an additional bracketing call to C<begin> and C<end> outside the |
636 |
|
|
loop, which serves two important purposes: first, it sets the callback |
637 |
|
|
to be called once the counter reaches C<0>, and second, it ensures that |
638 |
root |
1.106 |
C<send> is called even when C<no> hosts are being pinged (the loop |
639 |
root |
1.105 |
doesn't execute once). |
640 |
|
|
|
641 |
|
|
This is the general pattern when you "fan out" into multiple subrequests: |
642 |
|
|
use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
643 |
|
|
is called at least once, and then, for each subrequest you start, call |
644 |
elmex |
1.129 |
C<begin> and for each subrequest you finish, call C<end>. |
645 |
root |
1.105 |
|
646 |
|
|
=back |
647 |
|
|
|
648 |
|
|
=head3 METHODS FOR CONSUMERS |
649 |
|
|
|
650 |
|
|
These methods should only be used by the consuming side, i.e. the |
651 |
|
|
code awaits the condition. |
652 |
|
|
|
653 |
root |
1.106 |
=over 4 |
654 |
|
|
|
655 |
root |
1.114 |
=item $cv->recv |
656 |
root |
1.14 |
|
657 |
root |
1.106 |
Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
658 |
root |
1.105 |
>> methods have been called on c<$cv>, while servicing other watchers |
659 |
|
|
normally. |
660 |
|
|
|
661 |
|
|
You can only wait once on a condition - additional calls are valid but |
662 |
|
|
will return immediately. |
663 |
|
|
|
664 |
|
|
If an error condition has been set by calling C<< ->croak >>, then this |
665 |
|
|
function will call C<croak>. |
666 |
root |
1.14 |
|
667 |
root |
1.106 |
In list context, all parameters passed to C<send> will be returned, |
668 |
root |
1.105 |
in scalar context only the first one will be returned. |
669 |
root |
1.14 |
|
670 |
root |
1.47 |
Not all event models support a blocking wait - some die in that case |
671 |
root |
1.53 |
(programs might want to do that to stay interactive), so I<if you are |
672 |
|
|
using this from a module, never require a blocking wait>, but let the |
673 |
root |
1.52 |
caller decide whether the call will block or not (for example, by coupling |
674 |
root |
1.47 |
condition variables with some kind of request results and supporting |
675 |
|
|
callbacks so the caller knows that getting the result will not block, |
676 |
elmex |
1.129 |
while still supporting blocking waits if the caller so desires). |
677 |
root |
1.47 |
|
678 |
root |
1.114 |
Another reason I<never> to C<< ->recv >> in a module is that you cannot |
679 |
|
|
sensibly have two C<< ->recv >>'s in parallel, as that would require |
680 |
root |
1.47 |
multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
681 |
root |
1.108 |
can supply. |
682 |
|
|
|
683 |
|
|
The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
684 |
|
|
fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
685 |
|
|
versions and also integrates coroutines into AnyEvent, making blocking |
686 |
root |
1.114 |
C<< ->recv >> calls perfectly safe as long as they are done from another |
687 |
root |
1.108 |
coroutine (one that doesn't run the event loop). |
688 |
root |
1.47 |
|
689 |
root |
1.114 |
You can ensure that C<< -recv >> never blocks by setting a callback and |
690 |
|
|
only calling C<< ->recv >> from within that callback (or at a later |
691 |
root |
1.105 |
time). This will work even when the event loop does not support blocking |
692 |
|
|
waits otherwise. |
693 |
root |
1.53 |
|
694 |
root |
1.106 |
=item $bool = $cv->ready |
695 |
|
|
|
696 |
|
|
Returns true when the condition is "true", i.e. whether C<send> or |
697 |
|
|
C<croak> have been called. |
698 |
|
|
|
699 |
root |
1.173 |
=item $cb = $cv->cb ($cb->($cv)) |
700 |
root |
1.106 |
|
701 |
|
|
This is a mutator function that returns the callback set and optionally |
702 |
|
|
replaces it before doing so. |
703 |
|
|
|
704 |
|
|
The callback will be called when the condition becomes "true", i.e. when |
705 |
root |
1.149 |
C<send> or C<croak> are called, with the only argument being the condition |
706 |
|
|
variable itself. Calling C<recv> inside the callback or at any later time |
707 |
|
|
is guaranteed not to block. |
708 |
root |
1.106 |
|
709 |
root |
1.53 |
=back |
710 |
root |
1.14 |
|
711 |
root |
1.53 |
=head1 GLOBAL VARIABLES AND FUNCTIONS |
712 |
root |
1.16 |
|
713 |
|
|
=over 4 |
714 |
|
|
|
715 |
|
|
=item $AnyEvent::MODEL |
716 |
|
|
|
717 |
|
|
Contains C<undef> until the first watcher is being created. Then it |
718 |
|
|
contains the event model that is being used, which is the name of the |
719 |
|
|
Perl class implementing the model. This class is usually one of the |
720 |
|
|
C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
721 |
|
|
AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
722 |
|
|
|
723 |
|
|
The known classes so far are: |
724 |
|
|
|
725 |
root |
1.56 |
AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
726 |
|
|
AnyEvent::Impl::Event based on Event, second best choice. |
727 |
root |
1.104 |
AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
728 |
root |
1.48 |
AnyEvent::Impl::Glib based on Glib, third-best choice. |
729 |
root |
1.16 |
AnyEvent::Impl::Tk based on Tk, very bad choice. |
730 |
root |
1.56 |
AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
731 |
root |
1.55 |
AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
732 |
root |
1.61 |
AnyEvent::Impl::POE based on POE, not generic enough for full support. |
733 |
|
|
|
734 |
|
|
There is no support for WxWidgets, as WxWidgets has no support for |
735 |
|
|
watching file handles. However, you can use WxWidgets through the |
736 |
|
|
POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
737 |
|
|
second, which was considered to be too horrible to even consider for |
738 |
root |
1.62 |
AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
739 |
root |
1.61 |
it's adaptor. |
740 |
root |
1.16 |
|
741 |
root |
1.62 |
AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
742 |
|
|
autodetecting them. |
743 |
|
|
|
744 |
root |
1.19 |
=item AnyEvent::detect |
745 |
|
|
|
746 |
root |
1.53 |
Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
747 |
|
|
if necessary. You should only call this function right before you would |
748 |
|
|
have created an AnyEvent watcher anyway, that is, as late as possible at |
749 |
|
|
runtime. |
750 |
root |
1.19 |
|
751 |
root |
1.111 |
=item $guard = AnyEvent::post_detect { BLOCK } |
752 |
root |
1.109 |
|
753 |
|
|
Arranges for the code block to be executed as soon as the event model is |
754 |
|
|
autodetected (or immediately if this has already happened). |
755 |
|
|
|
756 |
root |
1.110 |
If called in scalar or list context, then it creates and returns an object |
757 |
root |
1.112 |
that automatically removes the callback again when it is destroyed. See |
758 |
|
|
L<Coro::BDB> for a case where this is useful. |
759 |
root |
1.110 |
|
760 |
root |
1.111 |
=item @AnyEvent::post_detect |
761 |
root |
1.108 |
|
762 |
|
|
If there are any code references in this array (you can C<push> to it |
763 |
|
|
before or after loading AnyEvent), then they will called directly after |
764 |
|
|
the event loop has been chosen. |
765 |
|
|
|
766 |
|
|
You should check C<$AnyEvent::MODEL> before adding to this array, though: |
767 |
|
|
if it contains a true value then the event loop has already been detected, |
768 |
|
|
and the array will be ignored. |
769 |
|
|
|
770 |
root |
1.111 |
Best use C<AnyEvent::post_detect { BLOCK }> instead. |
771 |
root |
1.109 |
|
772 |
root |
1.16 |
=back |
773 |
|
|
|
774 |
root |
1.14 |
=head1 WHAT TO DO IN A MODULE |
775 |
|
|
|
776 |
root |
1.53 |
As a module author, you should C<use AnyEvent> and call AnyEvent methods |
777 |
root |
1.14 |
freely, but you should not load a specific event module or rely on it. |
778 |
|
|
|
779 |
root |
1.53 |
Be careful when you create watchers in the module body - AnyEvent will |
780 |
root |
1.14 |
decide which event module to use as soon as the first method is called, so |
781 |
|
|
by calling AnyEvent in your module body you force the user of your module |
782 |
|
|
to load the event module first. |
783 |
|
|
|
784 |
root |
1.114 |
Never call C<< ->recv >> on a condition variable unless you I<know> that |
785 |
root |
1.106 |
the C<< ->send >> method has been called on it already. This is |
786 |
root |
1.53 |
because it will stall the whole program, and the whole point of using |
787 |
|
|
events is to stay interactive. |
788 |
|
|
|
789 |
root |
1.114 |
It is fine, however, to call C<< ->recv >> when the user of your module |
790 |
root |
1.53 |
requests it (i.e. if you create a http request object ad have a method |
791 |
root |
1.114 |
called C<results> that returns the results, it should call C<< ->recv >> |
792 |
root |
1.53 |
freely, as the user of your module knows what she is doing. always). |
793 |
|
|
|
794 |
root |
1.14 |
=head1 WHAT TO DO IN THE MAIN PROGRAM |
795 |
|
|
|
796 |
|
|
There will always be a single main program - the only place that should |
797 |
|
|
dictate which event model to use. |
798 |
|
|
|
799 |
|
|
If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
800 |
root |
1.53 |
do anything special (it does not need to be event-based) and let AnyEvent |
801 |
|
|
decide which implementation to chose if some module relies on it. |
802 |
root |
1.14 |
|
803 |
root |
1.134 |
If the main program relies on a specific event model - for example, in |
804 |
|
|
Gtk2 programs you have to rely on the Glib module - you should load the |
805 |
root |
1.53 |
event module before loading AnyEvent or any module that uses it: generally |
806 |
|
|
speaking, you should load it as early as possible. The reason is that |
807 |
|
|
modules might create watchers when they are loaded, and AnyEvent will |
808 |
|
|
decide on the event model to use as soon as it creates watchers, and it |
809 |
|
|
might chose the wrong one unless you load the correct one yourself. |
810 |
root |
1.14 |
|
811 |
root |
1.134 |
You can chose to use a pure-perl implementation by loading the |
812 |
|
|
C<AnyEvent::Impl::Perl> module, which gives you similar behaviour |
813 |
|
|
everywhere, but letting AnyEvent chose the model is generally better. |
814 |
|
|
|
815 |
|
|
=head2 MAINLOOP EMULATION |
816 |
|
|
|
817 |
|
|
Sometimes (often for short test scripts, or even standalone programs who |
818 |
|
|
only want to use AnyEvent), you do not want to run a specific event loop. |
819 |
|
|
|
820 |
|
|
In that case, you can use a condition variable like this: |
821 |
|
|
|
822 |
|
|
AnyEvent->condvar->recv; |
823 |
|
|
|
824 |
|
|
This has the effect of entering the event loop and looping forever. |
825 |
|
|
|
826 |
|
|
Note that usually your program has some exit condition, in which case |
827 |
|
|
it is better to use the "traditional" approach of storing a condition |
828 |
|
|
variable somewhere, waiting for it, and sending it when the program should |
829 |
|
|
exit cleanly. |
830 |
|
|
|
831 |
root |
1.14 |
|
832 |
elmex |
1.100 |
=head1 OTHER MODULES |
833 |
|
|
|
834 |
root |
1.101 |
The following is a non-exhaustive list of additional modules that use |
835 |
|
|
AnyEvent and can therefore be mixed easily with other AnyEvent modules |
836 |
|
|
in the same program. Some of the modules come with AnyEvent, some are |
837 |
|
|
available via CPAN. |
838 |
|
|
|
839 |
|
|
=over 4 |
840 |
|
|
|
841 |
|
|
=item L<AnyEvent::Util> |
842 |
|
|
|
843 |
|
|
Contains various utility functions that replace often-used but blocking |
844 |
|
|
functions such as C<inet_aton> by event-/callback-based versions. |
845 |
|
|
|
846 |
root |
1.125 |
=item L<AnyEvent::Socket> |
847 |
|
|
|
848 |
|
|
Provides various utility functions for (internet protocol) sockets, |
849 |
|
|
addresses and name resolution. Also functions to create non-blocking tcp |
850 |
|
|
connections or tcp servers, with IPv6 and SRV record support and more. |
851 |
|
|
|
852 |
root |
1.164 |
=item L<AnyEvent::Handle> |
853 |
|
|
|
854 |
|
|
Provide read and write buffers, manages watchers for reads and writes, |
855 |
|
|
supports raw and formatted I/O, I/O queued and fully transparent and |
856 |
|
|
non-blocking SSL/TLS. |
857 |
|
|
|
858 |
root |
1.134 |
=item L<AnyEvent::DNS> |
859 |
|
|
|
860 |
|
|
Provides rich asynchronous DNS resolver capabilities. |
861 |
|
|
|
862 |
root |
1.155 |
=item L<AnyEvent::HTTP> |
863 |
|
|
|
864 |
|
|
A simple-to-use HTTP library that is capable of making a lot of concurrent |
865 |
|
|
HTTP requests. |
866 |
|
|
|
867 |
root |
1.101 |
=item L<AnyEvent::HTTPD> |
868 |
|
|
|
869 |
|
|
Provides a simple web application server framework. |
870 |
|
|
|
871 |
elmex |
1.100 |
=item L<AnyEvent::FastPing> |
872 |
|
|
|
873 |
root |
1.101 |
The fastest ping in the west. |
874 |
|
|
|
875 |
root |
1.159 |
=item L<AnyEvent::DBI> |
876 |
|
|
|
877 |
root |
1.164 |
Executes L<DBI> requests asynchronously in a proxy process. |
878 |
|
|
|
879 |
|
|
=item L<AnyEvent::AIO> |
880 |
|
|
|
881 |
|
|
Truly asynchronous I/O, should be in the toolbox of every event |
882 |
|
|
programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent |
883 |
|
|
together. |
884 |
|
|
|
885 |
|
|
=item L<AnyEvent::BDB> |
886 |
|
|
|
887 |
|
|
Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses |
888 |
|
|
L<BDB> and AnyEvent together. |
889 |
|
|
|
890 |
|
|
=item L<AnyEvent::GPSD> |
891 |
|
|
|
892 |
|
|
A non-blocking interface to gpsd, a daemon delivering GPS information. |
893 |
|
|
|
894 |
|
|
=item L<AnyEvent::IGS> |
895 |
|
|
|
896 |
|
|
A non-blocking interface to the Internet Go Server protocol (used by |
897 |
|
|
L<App::IGS>). |
898 |
root |
1.159 |
|
899 |
root |
1.184 |
=item L<AnyEvent::IRC> |
900 |
elmex |
1.100 |
|
901 |
root |
1.184 |
AnyEvent based IRC client module family (replacing the older Net::IRC3). |
902 |
root |
1.101 |
|
903 |
elmex |
1.100 |
=item L<Net::XMPP2> |
904 |
|
|
|
905 |
root |
1.101 |
AnyEvent based XMPP (Jabber protocol) module family. |
906 |
|
|
|
907 |
|
|
=item L<Net::FCP> |
908 |
|
|
|
909 |
|
|
AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
910 |
|
|
of AnyEvent. |
911 |
|
|
|
912 |
|
|
=item L<Event::ExecFlow> |
913 |
|
|
|
914 |
|
|
High level API for event-based execution flow control. |
915 |
|
|
|
916 |
|
|
=item L<Coro> |
917 |
|
|
|
918 |
root |
1.108 |
Has special support for AnyEvent via L<Coro::AnyEvent>. |
919 |
root |
1.101 |
|
920 |
root |
1.113 |
=item L<IO::Lambda> |
921 |
root |
1.101 |
|
922 |
root |
1.113 |
The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
923 |
root |
1.101 |
|
924 |
elmex |
1.100 |
=back |
925 |
|
|
|
926 |
root |
1.1 |
=cut |
927 |
|
|
|
928 |
|
|
package AnyEvent; |
929 |
|
|
|
930 |
root |
1.2 |
no warnings; |
931 |
root |
1.180 |
use strict qw(vars subs); |
932 |
root |
1.24 |
|
933 |
root |
1.1 |
use Carp; |
934 |
|
|
|
935 |
root |
1.208 |
our $VERSION = 4.4; |
936 |
root |
1.2 |
our $MODEL; |
937 |
root |
1.1 |
|
938 |
root |
1.2 |
our $AUTOLOAD; |
939 |
|
|
our @ISA; |
940 |
root |
1.1 |
|
941 |
root |
1.135 |
our @REGISTRY; |
942 |
|
|
|
943 |
root |
1.138 |
our $WIN32; |
944 |
|
|
|
945 |
|
|
BEGIN { |
946 |
|
|
my $win32 = ! ! ($^O =~ /mswin32/i); |
947 |
|
|
eval "sub WIN32(){ $win32 }"; |
948 |
|
|
} |
949 |
|
|
|
950 |
root |
1.7 |
our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
951 |
|
|
|
952 |
root |
1.136 |
our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
953 |
root |
1.126 |
|
954 |
|
|
{ |
955 |
|
|
my $idx; |
956 |
|
|
$PROTOCOL{$_} = ++$idx |
957 |
root |
1.136 |
for reverse split /\s*,\s*/, |
958 |
|
|
$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
959 |
root |
1.126 |
} |
960 |
|
|
|
961 |
root |
1.1 |
my @models = ( |
962 |
root |
1.33 |
[EV:: => AnyEvent::Impl::EV::], |
963 |
root |
1.18 |
[Event:: => AnyEvent::Impl::Event::], |
964 |
|
|
[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
965 |
root |
1.135 |
# everything below here will not be autoprobed |
966 |
|
|
# as the pureperl backend should work everywhere |
967 |
|
|
# and is usually faster |
968 |
|
|
[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles |
969 |
|
|
[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers |
970 |
root |
1.61 |
[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
971 |
root |
1.56 |
[Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
972 |
root |
1.61 |
[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
973 |
root |
1.135 |
[Wx:: => AnyEvent::Impl::POE::], |
974 |
|
|
[Prima:: => AnyEvent::Impl::POE::], |
975 |
root |
1.1 |
); |
976 |
|
|
|
977 |
root |
1.205 |
our %method = map +($_ => 1), |
978 |
root |
1.207 |
qw(io timer time now now_update signal child idle condvar one_event DESTROY); |
979 |
root |
1.3 |
|
980 |
root |
1.111 |
our @post_detect; |
981 |
root |
1.109 |
|
982 |
root |
1.111 |
sub post_detect(&) { |
983 |
root |
1.110 |
my ($cb) = @_; |
984 |
|
|
|
985 |
root |
1.109 |
if ($MODEL) { |
986 |
root |
1.110 |
$cb->(); |
987 |
|
|
|
988 |
|
|
1 |
989 |
root |
1.109 |
} else { |
990 |
root |
1.111 |
push @post_detect, $cb; |
991 |
root |
1.110 |
|
992 |
|
|
defined wantarray |
993 |
root |
1.207 |
? bless \$cb, "AnyEvent::Util::postdetect" |
994 |
root |
1.110 |
: () |
995 |
root |
1.109 |
} |
996 |
|
|
} |
997 |
root |
1.108 |
|
998 |
root |
1.207 |
sub AnyEvent::Util::postdetect::DESTROY { |
999 |
root |
1.111 |
@post_detect = grep $_ != ${$_[0]}, @post_detect; |
1000 |
root |
1.110 |
} |
1001 |
|
|
|
1002 |
root |
1.19 |
sub detect() { |
1003 |
|
|
unless ($MODEL) { |
1004 |
|
|
no strict 'refs'; |
1005 |
root |
1.137 |
local $SIG{__DIE__}; |
1006 |
root |
1.1 |
|
1007 |
root |
1.55 |
if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
1008 |
|
|
my $model = "AnyEvent::Impl::$1"; |
1009 |
|
|
if (eval "require $model") { |
1010 |
|
|
$MODEL = $model; |
1011 |
|
|
warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
1012 |
root |
1.60 |
} else { |
1013 |
|
|
warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
1014 |
root |
1.2 |
} |
1015 |
root |
1.1 |
} |
1016 |
|
|
|
1017 |
root |
1.55 |
# check for already loaded models |
1018 |
root |
1.2 |
unless ($MODEL) { |
1019 |
root |
1.61 |
for (@REGISTRY, @models) { |
1020 |
root |
1.8 |
my ($package, $model) = @$_; |
1021 |
root |
1.55 |
if (${"$package\::VERSION"} > 0) { |
1022 |
|
|
if (eval "require $model") { |
1023 |
|
|
$MODEL = $model; |
1024 |
|
|
warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
1025 |
|
|
last; |
1026 |
|
|
} |
1027 |
root |
1.8 |
} |
1028 |
root |
1.2 |
} |
1029 |
|
|
|
1030 |
root |
1.55 |
unless ($MODEL) { |
1031 |
|
|
# try to load a model |
1032 |
|
|
|
1033 |
|
|
for (@REGISTRY, @models) { |
1034 |
|
|
my ($package, $model) = @$_; |
1035 |
|
|
if (eval "require $package" |
1036 |
|
|
and ${"$package\::VERSION"} > 0 |
1037 |
|
|
and eval "require $model") { |
1038 |
|
|
$MODEL = $model; |
1039 |
|
|
warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
1040 |
|
|
last; |
1041 |
|
|
} |
1042 |
|
|
} |
1043 |
|
|
|
1044 |
|
|
$MODEL |
1045 |
root |
1.204 |
or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n"; |
1046 |
root |
1.55 |
} |
1047 |
root |
1.1 |
} |
1048 |
root |
1.19 |
|
1049 |
|
|
push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
1050 |
root |
1.108 |
|
1051 |
root |
1.168 |
unshift @ISA, $MODEL; |
1052 |
|
|
|
1053 |
|
|
require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT}; |
1054 |
root |
1.167 |
|
1055 |
root |
1.111 |
(shift @post_detect)->() while @post_detect; |
1056 |
root |
1.1 |
} |
1057 |
|
|
|
1058 |
root |
1.19 |
$MODEL |
1059 |
|
|
} |
1060 |
|
|
|
1061 |
|
|
sub AUTOLOAD { |
1062 |
|
|
(my $func = $AUTOLOAD) =~ s/.*://; |
1063 |
|
|
|
1064 |
|
|
$method{$func} |
1065 |
|
|
or croak "$func: not a valid method for AnyEvent objects"; |
1066 |
|
|
|
1067 |
|
|
detect unless $MODEL; |
1068 |
root |
1.2 |
|
1069 |
|
|
my $class = shift; |
1070 |
root |
1.18 |
$class->$func (@_); |
1071 |
root |
1.1 |
} |
1072 |
|
|
|
1073 |
root |
1.169 |
# utility function to dup a filehandle. this is used by many backends |
1074 |
|
|
# to support binding more than one watcher per filehandle (they usually |
1075 |
|
|
# allow only one watcher per fd, so we dup it to get a different one). |
1076 |
|
|
sub _dupfh($$$$) { |
1077 |
|
|
my ($poll, $fh, $r, $w) = @_; |
1078 |
|
|
|
1079 |
|
|
# cygwin requires the fh mode to be matching, unix doesn't |
1080 |
|
|
my ($rw, $mode) = $poll eq "r" ? ($r, "<") |
1081 |
|
|
: $poll eq "w" ? ($w, ">") |
1082 |
|
|
: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'"; |
1083 |
|
|
|
1084 |
|
|
open my $fh2, "$mode&" . fileno $fh |
1085 |
root |
1.204 |
or die "cannot dup() filehandle: $!,"; |
1086 |
root |
1.169 |
|
1087 |
|
|
# we assume CLOEXEC is already set by perl in all important cases |
1088 |
|
|
|
1089 |
|
|
($fh2, $rw) |
1090 |
|
|
} |
1091 |
|
|
|
1092 |
root |
1.19 |
package AnyEvent::Base; |
1093 |
|
|
|
1094 |
root |
1.205 |
# default implementations for many methods |
1095 |
root |
1.143 |
|
1096 |
root |
1.179 |
BEGIN { |
1097 |
root |
1.207 |
if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { |
1098 |
root |
1.179 |
*_time = \&Time::HiRes::time; |
1099 |
|
|
# if (eval "use POSIX (); (POSIX::times())... |
1100 |
|
|
} else { |
1101 |
root |
1.182 |
*_time = sub { time }; # epic fail |
1102 |
root |
1.179 |
} |
1103 |
|
|
} |
1104 |
root |
1.143 |
|
1105 |
root |
1.179 |
sub time { _time } |
1106 |
|
|
sub now { _time } |
1107 |
root |
1.205 |
sub now_update { } |
1108 |
root |
1.143 |
|
1109 |
root |
1.114 |
# default implementation for ->condvar |
1110 |
root |
1.20 |
|
1111 |
|
|
sub condvar { |
1112 |
root |
1.207 |
bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" |
1113 |
root |
1.20 |
} |
1114 |
|
|
|
1115 |
|
|
# default implementation for ->signal |
1116 |
root |
1.19 |
|
1117 |
root |
1.195 |
our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); |
1118 |
|
|
|
1119 |
|
|
sub _signal_exec { |
1120 |
root |
1.198 |
sysread $SIGPIPE_R, my $dummy, 4; |
1121 |
|
|
|
1122 |
root |
1.195 |
while (%SIG_EV) { |
1123 |
|
|
for (keys %SIG_EV) { |
1124 |
|
|
delete $SIG_EV{$_}; |
1125 |
|
|
$_->() for values %{ $SIG_CB{$_} || {} }; |
1126 |
|
|
} |
1127 |
|
|
} |
1128 |
|
|
} |
1129 |
root |
1.19 |
|
1130 |
|
|
sub signal { |
1131 |
|
|
my (undef, %arg) = @_; |
1132 |
|
|
|
1133 |
root |
1.195 |
unless ($SIGPIPE_R) { |
1134 |
root |
1.200 |
require Fcntl; |
1135 |
|
|
|
1136 |
root |
1.195 |
if (AnyEvent::WIN32) { |
1137 |
root |
1.200 |
require AnyEvent::Util; |
1138 |
|
|
|
1139 |
root |
1.195 |
($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe (); |
1140 |
|
|
AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R; |
1141 |
|
|
AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case |
1142 |
|
|
} else { |
1143 |
|
|
pipe $SIGPIPE_R, $SIGPIPE_W; |
1144 |
|
|
fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R; |
1145 |
|
|
fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case |
1146 |
|
|
} |
1147 |
|
|
|
1148 |
|
|
$SIGPIPE_R |
1149 |
|
|
or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; |
1150 |
|
|
|
1151 |
root |
1.201 |
# not strictly required, as $^F is normally 2, but let's make sure... |
1152 |
root |
1.200 |
fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; |
1153 |
|
|
fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; |
1154 |
|
|
|
1155 |
root |
1.195 |
$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec); |
1156 |
|
|
} |
1157 |
|
|
|
1158 |
root |
1.19 |
my $signal = uc $arg{signal} |
1159 |
|
|
or Carp::croak "required option 'signal' is missing"; |
1160 |
|
|
|
1161 |
root |
1.31 |
$SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
1162 |
root |
1.19 |
$SIG{$signal} ||= sub { |
1163 |
root |
1.202 |
local $!; |
1164 |
root |
1.195 |
syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV; |
1165 |
|
|
undef $SIG_EV{$signal}; |
1166 |
root |
1.19 |
}; |
1167 |
|
|
|
1168 |
root |
1.207 |
bless [$signal, $arg{cb}], "AnyEvent::Base::signal" |
1169 |
root |
1.19 |
} |
1170 |
|
|
|
1171 |
root |
1.207 |
sub AnyEvent::Base::signal::DESTROY { |
1172 |
root |
1.19 |
my ($signal, $cb) = @{$_[0]}; |
1173 |
|
|
|
1174 |
|
|
delete $SIG_CB{$signal}{$cb}; |
1175 |
|
|
|
1176 |
root |
1.161 |
delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; |
1177 |
root |
1.19 |
} |
1178 |
|
|
|
1179 |
root |
1.20 |
# default implementation for ->child |
1180 |
|
|
|
1181 |
|
|
our %PID_CB; |
1182 |
|
|
our $CHLD_W; |
1183 |
root |
1.37 |
our $CHLD_DELAY_W; |
1184 |
root |
1.20 |
our $PID_IDLE; |
1185 |
|
|
our $WNOHANG; |
1186 |
|
|
|
1187 |
|
|
sub _child_wait { |
1188 |
root |
1.38 |
while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
1189 |
root |
1.32 |
$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
1190 |
|
|
(values %{ $PID_CB{0} || {} }); |
1191 |
root |
1.20 |
} |
1192 |
|
|
|
1193 |
|
|
undef $PID_IDLE; |
1194 |
|
|
} |
1195 |
|
|
|
1196 |
root |
1.37 |
sub _sigchld { |
1197 |
|
|
# make sure we deliver these changes "synchronous" with the event loop. |
1198 |
|
|
$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
1199 |
|
|
undef $CHLD_DELAY_W; |
1200 |
|
|
&_child_wait; |
1201 |
|
|
}); |
1202 |
|
|
} |
1203 |
|
|
|
1204 |
root |
1.20 |
sub child { |
1205 |
|
|
my (undef, %arg) = @_; |
1206 |
|
|
|
1207 |
root |
1.31 |
defined (my $pid = $arg{pid} + 0) |
1208 |
root |
1.20 |
or Carp::croak "required option 'pid' is missing"; |
1209 |
|
|
|
1210 |
|
|
$PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
1211 |
|
|
|
1212 |
|
|
unless ($WNOHANG) { |
1213 |
root |
1.137 |
$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; |
1214 |
root |
1.20 |
} |
1215 |
|
|
|
1216 |
root |
1.23 |
unless ($CHLD_W) { |
1217 |
root |
1.37 |
$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
1218 |
|
|
# child could be a zombie already, so make at least one round |
1219 |
|
|
&_sigchld; |
1220 |
root |
1.23 |
} |
1221 |
root |
1.20 |
|
1222 |
root |
1.207 |
bless [$pid, $arg{cb}], "AnyEvent::Base::child" |
1223 |
root |
1.20 |
} |
1224 |
|
|
|
1225 |
root |
1.207 |
sub AnyEvent::Base::child::DESTROY { |
1226 |
root |
1.20 |
my ($pid, $cb) = @{$_[0]}; |
1227 |
|
|
|
1228 |
|
|
delete $PID_CB{$pid}{$cb}; |
1229 |
|
|
delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
1230 |
|
|
|
1231 |
|
|
undef $CHLD_W unless keys %PID_CB; |
1232 |
|
|
} |
1233 |
|
|
|
1234 |
root |
1.207 |
# idle emulation is done by simply using a timer, regardless |
1235 |
|
|
# of whether the proces sis idle or not, and not letting |
1236 |
|
|
# the callback use more than 50% of the time. |
1237 |
|
|
sub idle { |
1238 |
|
|
my (undef, %arg) = @_; |
1239 |
|
|
|
1240 |
|
|
my ($cb, $w, $rcb) = $arg{cb}; |
1241 |
|
|
|
1242 |
|
|
$rcb = sub { |
1243 |
|
|
if ($cb) { |
1244 |
|
|
$w = _time; |
1245 |
|
|
&$cb; |
1246 |
|
|
$w = _time - $w; |
1247 |
|
|
|
1248 |
|
|
# never use more then 50% of the time for the idle watcher, |
1249 |
|
|
# within some limits |
1250 |
|
|
$w = 0.0001 if $w < 0.0001; |
1251 |
|
|
$w = 5 if $w > 5; |
1252 |
|
|
|
1253 |
|
|
$w = AnyEvent->timer (after => $w, cb => $rcb); |
1254 |
|
|
} else { |
1255 |
|
|
# clean up... |
1256 |
|
|
undef $w; |
1257 |
|
|
undef $rcb; |
1258 |
|
|
} |
1259 |
|
|
}; |
1260 |
|
|
|
1261 |
|
|
$w = AnyEvent->timer (after => 0.05, cb => $rcb); |
1262 |
|
|
|
1263 |
|
|
bless \\$cb, "AnyEvent::Base::idle" |
1264 |
|
|
} |
1265 |
|
|
|
1266 |
|
|
sub AnyEvent::Base::idle::DESTROY { |
1267 |
|
|
undef $${$_[0]}; |
1268 |
|
|
} |
1269 |
|
|
|
1270 |
root |
1.116 |
package AnyEvent::CondVar; |
1271 |
|
|
|
1272 |
|
|
our @ISA = AnyEvent::CondVar::Base::; |
1273 |
|
|
|
1274 |
|
|
package AnyEvent::CondVar::Base; |
1275 |
root |
1.114 |
|
1276 |
root |
1.131 |
use overload |
1277 |
|
|
'&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
1278 |
|
|
fallback => 1; |
1279 |
|
|
|
1280 |
root |
1.114 |
sub _send { |
1281 |
root |
1.116 |
# nop |
1282 |
root |
1.114 |
} |
1283 |
|
|
|
1284 |
|
|
sub send { |
1285 |
root |
1.115 |
my $cv = shift; |
1286 |
|
|
$cv->{_ae_sent} = [@_]; |
1287 |
root |
1.116 |
(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
1288 |
root |
1.115 |
$cv->_send; |
1289 |
root |
1.114 |
} |
1290 |
|
|
|
1291 |
|
|
sub croak { |
1292 |
root |
1.115 |
$_[0]{_ae_croak} = $_[1]; |
1293 |
root |
1.114 |
$_[0]->send; |
1294 |
|
|
} |
1295 |
|
|
|
1296 |
|
|
sub ready { |
1297 |
|
|
$_[0]{_ae_sent} |
1298 |
|
|
} |
1299 |
|
|
|
1300 |
root |
1.116 |
sub _wait { |
1301 |
|
|
AnyEvent->one_event while !$_[0]{_ae_sent}; |
1302 |
|
|
} |
1303 |
|
|
|
1304 |
root |
1.114 |
sub recv { |
1305 |
root |
1.116 |
$_[0]->_wait; |
1306 |
root |
1.114 |
|
1307 |
|
|
Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
1308 |
|
|
wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
1309 |
|
|
} |
1310 |
|
|
|
1311 |
|
|
sub cb { |
1312 |
|
|
$_[0]{_ae_cb} = $_[1] if @_ > 1; |
1313 |
|
|
$_[0]{_ae_cb} |
1314 |
|
|
} |
1315 |
|
|
|
1316 |
|
|
sub begin { |
1317 |
|
|
++$_[0]{_ae_counter}; |
1318 |
|
|
$_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
1319 |
|
|
} |
1320 |
|
|
|
1321 |
|
|
sub end { |
1322 |
|
|
return if --$_[0]{_ae_counter}; |
1323 |
root |
1.124 |
&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
1324 |
root |
1.114 |
} |
1325 |
|
|
|
1326 |
|
|
# undocumented/compatibility with pre-3.4 |
1327 |
|
|
*broadcast = \&send; |
1328 |
root |
1.116 |
*wait = \&_wait; |
1329 |
root |
1.114 |
|
1330 |
root |
1.180 |
=head1 ERROR AND EXCEPTION HANDLING |
1331 |
root |
1.53 |
|
1332 |
root |
1.180 |
In general, AnyEvent does not do any error handling - it relies on the |
1333 |
|
|
caller to do that if required. The L<AnyEvent::Strict> module (see also |
1334 |
|
|
the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict |
1335 |
|
|
checking of all AnyEvent methods, however, which is highly useful during |
1336 |
|
|
development. |
1337 |
|
|
|
1338 |
|
|
As for exception handling (i.e. runtime errors and exceptions thrown while |
1339 |
|
|
executing a callback), this is not only highly event-loop specific, but |
1340 |
|
|
also not in any way wrapped by this module, as this is the job of the main |
1341 |
|
|
program. |
1342 |
|
|
|
1343 |
|
|
The pure perl event loop simply re-throws the exception (usually |
1344 |
|
|
within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<< |
1345 |
|
|
$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and |
1346 |
|
|
so on. |
1347 |
root |
1.12 |
|
1348 |
root |
1.7 |
=head1 ENVIRONMENT VARIABLES |
1349 |
|
|
|
1350 |
root |
1.180 |
The following environment variables are used by this module or its |
1351 |
|
|
submodules: |
1352 |
root |
1.7 |
|
1353 |
root |
1.55 |
=over 4 |
1354 |
|
|
|
1355 |
|
|
=item C<PERL_ANYEVENT_VERBOSE> |
1356 |
|
|
|
1357 |
root |
1.60 |
By default, AnyEvent will be completely silent except in fatal |
1358 |
|
|
conditions. You can set this environment variable to make AnyEvent more |
1359 |
|
|
talkative. |
1360 |
|
|
|
1361 |
|
|
When set to C<1> or higher, causes AnyEvent to warn about unexpected |
1362 |
|
|
conditions, such as not being able to load the event model specified by |
1363 |
|
|
C<PERL_ANYEVENT_MODEL>. |
1364 |
|
|
|
1365 |
root |
1.55 |
When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
1366 |
|
|
model it chooses. |
1367 |
|
|
|
1368 |
root |
1.167 |
=item C<PERL_ANYEVENT_STRICT> |
1369 |
|
|
|
1370 |
|
|
AnyEvent does not do much argument checking by default, as thorough |
1371 |
|
|
argument checking is very costly. Setting this variable to a true value |
1372 |
root |
1.170 |
will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly |
1373 |
|
|
check the arguments passed to most method calls. If it finds any problems |
1374 |
|
|
it will croak. |
1375 |
|
|
|
1376 |
|
|
In other words, enables "strict" mode. |
1377 |
|
|
|
1378 |
root |
1.180 |
Unlike C<use strict>, it is definitely recommended ot keep it off in |
1379 |
|
|
production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while |
1380 |
|
|
developing programs can be very useful, however. |
1381 |
root |
1.167 |
|
1382 |
root |
1.55 |
=item C<PERL_ANYEVENT_MODEL> |
1383 |
|
|
|
1384 |
|
|
This can be used to specify the event model to be used by AnyEvent, before |
1385 |
root |
1.128 |
auto detection and -probing kicks in. It must be a string consisting |
1386 |
root |
1.55 |
entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
1387 |
|
|
and the resulting module name is loaded and if the load was successful, |
1388 |
|
|
used as event model. If it fails to load AnyEvent will proceed with |
1389 |
root |
1.128 |
auto detection and -probing. |
1390 |
root |
1.55 |
|
1391 |
|
|
This functionality might change in future versions. |
1392 |
|
|
|
1393 |
|
|
For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
1394 |
|
|
could start your program like this: |
1395 |
|
|
|
1396 |
root |
1.151 |
PERL_ANYEVENT_MODEL=Perl perl ... |
1397 |
root |
1.55 |
|
1398 |
root |
1.125 |
=item C<PERL_ANYEVENT_PROTOCOLS> |
1399 |
|
|
|
1400 |
|
|
Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
1401 |
|
|
for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
1402 |
root |
1.128 |
of auto probing). |
1403 |
root |
1.125 |
|
1404 |
|
|
Must be set to a comma-separated list of protocols or address families, |
1405 |
|
|
current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
1406 |
|
|
used, and preference will be given to protocols mentioned earlier in the |
1407 |
|
|
list. |
1408 |
|
|
|
1409 |
root |
1.127 |
This variable can effectively be used for denial-of-service attacks |
1410 |
|
|
against local programs (e.g. when setuid), although the impact is likely |
1411 |
root |
1.194 |
small, as the program has to handle conenction and other failures anyways. |
1412 |
root |
1.127 |
|
1413 |
root |
1.125 |
Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
1414 |
|
|
but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
1415 |
|
|
- only support IPv4, never try to resolve or contact IPv6 |
1416 |
root |
1.128 |
addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
1417 |
root |
1.125 |
IPv6, but prefer IPv6 over IPv4. |
1418 |
|
|
|
1419 |
root |
1.127 |
=item C<PERL_ANYEVENT_EDNS0> |
1420 |
|
|
|
1421 |
root |
1.128 |
Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
1422 |
root |
1.127 |
for DNS. This extension is generally useful to reduce DNS traffic, but |
1423 |
|
|
some (broken) firewalls drop such DNS packets, which is why it is off by |
1424 |
|
|
default. |
1425 |
|
|
|
1426 |
|
|
Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
1427 |
|
|
EDNS0 in its DNS requests. |
1428 |
|
|
|
1429 |
root |
1.142 |
=item C<PERL_ANYEVENT_MAX_FORKS> |
1430 |
|
|
|
1431 |
|
|
The maximum number of child processes that C<AnyEvent::Util::fork_call> |
1432 |
|
|
will create in parallel. |
1433 |
|
|
|
1434 |
root |
1.55 |
=back |
1435 |
root |
1.7 |
|
1436 |
root |
1.180 |
=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1437 |
|
|
|
1438 |
|
|
This is an advanced topic that you do not normally need to use AnyEvent in |
1439 |
|
|
a module. This section is only of use to event loop authors who want to |
1440 |
|
|
provide AnyEvent compatibility. |
1441 |
|
|
|
1442 |
|
|
If you need to support another event library which isn't directly |
1443 |
|
|
supported by AnyEvent, you can supply your own interface to it by |
1444 |
|
|
pushing, before the first watcher gets created, the package name of |
1445 |
|
|
the event module and the package name of the interface to use onto |
1446 |
|
|
C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
1447 |
|
|
AnyEvent, so it is reasonably cheap. |
1448 |
|
|
|
1449 |
|
|
Example: |
1450 |
|
|
|
1451 |
|
|
push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
1452 |
|
|
|
1453 |
|
|
This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
1454 |
|
|
package/class when it finds the C<urxvt> package/module is already loaded. |
1455 |
|
|
|
1456 |
|
|
When AnyEvent is loaded and asked to find a suitable event model, it |
1457 |
|
|
will first check for the presence of urxvt by trying to C<use> the |
1458 |
|
|
C<urxvt::anyevent> module. |
1459 |
|
|
|
1460 |
|
|
The class should provide implementations for all watcher types. See |
1461 |
|
|
L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
1462 |
|
|
and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
1463 |
|
|
see the sources. |
1464 |
|
|
|
1465 |
|
|
If you don't provide C<signal> and C<child> watchers than AnyEvent will |
1466 |
|
|
provide suitable (hopefully) replacements. |
1467 |
|
|
|
1468 |
|
|
The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
1469 |
|
|
terminal emulator uses the above line as-is. An interface isn't included |
1470 |
|
|
in AnyEvent because it doesn't make sense outside the embedded interpreter |
1471 |
|
|
inside I<rxvt-unicode>, and it is updated and maintained as part of the |
1472 |
|
|
I<rxvt-unicode> distribution. |
1473 |
|
|
|
1474 |
|
|
I<rxvt-unicode> also cheats a bit by not providing blocking access to |
1475 |
|
|
condition variables: code blocking while waiting for a condition will |
1476 |
|
|
C<die>. This still works with most modules/usages, and blocking calls must |
1477 |
|
|
not be done in an interactive application, so it makes sense. |
1478 |
|
|
|
1479 |
root |
1.53 |
=head1 EXAMPLE PROGRAM |
1480 |
root |
1.2 |
|
1481 |
root |
1.78 |
The following program uses an I/O watcher to read data from STDIN, a timer |
1482 |
root |
1.53 |
to display a message once per second, and a condition variable to quit the |
1483 |
|
|
program when the user enters quit: |
1484 |
root |
1.2 |
|
1485 |
|
|
use AnyEvent; |
1486 |
|
|
|
1487 |
|
|
my $cv = AnyEvent->condvar; |
1488 |
|
|
|
1489 |
root |
1.53 |
my $io_watcher = AnyEvent->io ( |
1490 |
|
|
fh => \*STDIN, |
1491 |
|
|
poll => 'r', |
1492 |
|
|
cb => sub { |
1493 |
|
|
warn "io event <$_[0]>\n"; # will always output <r> |
1494 |
|
|
chomp (my $input = <STDIN>); # read a line |
1495 |
|
|
warn "read: $input\n"; # output what has been read |
1496 |
root |
1.118 |
$cv->send if $input =~ /^q/i; # quit program if /^q/i |
1497 |
root |
1.53 |
}, |
1498 |
|
|
); |
1499 |
root |
1.2 |
|
1500 |
|
|
my $time_watcher; # can only be used once |
1501 |
|
|
|
1502 |
|
|
sub new_timer { |
1503 |
|
|
$timer = AnyEvent->timer (after => 1, cb => sub { |
1504 |
|
|
warn "timeout\n"; # print 'timeout' about every second |
1505 |
|
|
&new_timer; # and restart the time |
1506 |
|
|
}); |
1507 |
|
|
} |
1508 |
|
|
|
1509 |
|
|
new_timer; # create first timer |
1510 |
|
|
|
1511 |
root |
1.118 |
$cv->recv; # wait until user enters /^q/i |
1512 |
root |
1.2 |
|
1513 |
root |
1.5 |
=head1 REAL-WORLD EXAMPLE |
1514 |
|
|
|
1515 |
|
|
Consider the L<Net::FCP> module. It features (among others) the following |
1516 |
|
|
API calls, which are to freenet what HTTP GET requests are to http: |
1517 |
|
|
|
1518 |
|
|
my $data = $fcp->client_get ($url); # blocks |
1519 |
|
|
|
1520 |
|
|
my $transaction = $fcp->txn_client_get ($url); # does not block |
1521 |
|
|
$transaction->cb ( sub { ... } ); # set optional result callback |
1522 |
|
|
my $data = $transaction->result; # possibly blocks |
1523 |
|
|
|
1524 |
|
|
The C<client_get> method works like C<LWP::Simple::get>: it requests the |
1525 |
|
|
given URL and waits till the data has arrived. It is defined to be: |
1526 |
|
|
|
1527 |
|
|
sub client_get { $_[0]->txn_client_get ($_[1])->result } |
1528 |
|
|
|
1529 |
|
|
And in fact is automatically generated. This is the blocking API of |
1530 |
|
|
L<Net::FCP>, and it works as simple as in any other, similar, module. |
1531 |
|
|
|
1532 |
|
|
More complicated is C<txn_client_get>: It only creates a transaction |
1533 |
|
|
(completion, result, ...) object and initiates the transaction. |
1534 |
|
|
|
1535 |
|
|
my $txn = bless { }, Net::FCP::Txn::; |
1536 |
|
|
|
1537 |
|
|
It also creates a condition variable that is used to signal the completion |
1538 |
|
|
of the request: |
1539 |
|
|
|
1540 |
|
|
$txn->{finished} = AnyAvent->condvar; |
1541 |
|
|
|
1542 |
|
|
It then creates a socket in non-blocking mode. |
1543 |
|
|
|
1544 |
|
|
socket $txn->{fh}, ...; |
1545 |
|
|
fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
1546 |
|
|
connect $txn->{fh}, ... |
1547 |
|
|
and !$!{EWOULDBLOCK} |
1548 |
|
|
and !$!{EINPROGRESS} |
1549 |
|
|
and Carp::croak "unable to connect: $!\n"; |
1550 |
|
|
|
1551 |
root |
1.6 |
Then it creates a write-watcher which gets called whenever an error occurs |
1552 |
root |
1.5 |
or the connection succeeds: |
1553 |
|
|
|
1554 |
|
|
$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
1555 |
|
|
|
1556 |
|
|
And returns this transaction object. The C<fh_ready_w> callback gets |
1557 |
|
|
called as soon as the event loop detects that the socket is ready for |
1558 |
|
|
writing. |
1559 |
|
|
|
1560 |
|
|
The C<fh_ready_w> method makes the socket blocking again, writes the |
1561 |
|
|
request data and replaces the watcher by a read watcher (waiting for reply |
1562 |
|
|
data). The actual code is more complicated, but that doesn't matter for |
1563 |
|
|
this example: |
1564 |
|
|
|
1565 |
|
|
fcntl $txn->{fh}, F_SETFL, 0; |
1566 |
|
|
syswrite $txn->{fh}, $txn->{request} |
1567 |
|
|
or die "connection or write error"; |
1568 |
|
|
$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1569 |
|
|
|
1570 |
|
|
Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1571 |
root |
1.128 |
result and signals any possible waiters that the request has finished: |
1572 |
root |
1.5 |
|
1573 |
|
|
sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1574 |
|
|
|
1575 |
|
|
if (end-of-file or data complete) { |
1576 |
|
|
$txn->{result} = $txn->{buf}; |
1577 |
root |
1.118 |
$txn->{finished}->send; |
1578 |
root |
1.6 |
$txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1579 |
root |
1.5 |
} |
1580 |
|
|
|
1581 |
|
|
The C<result> method, finally, just waits for the finished signal (if the |
1582 |
|
|
request was already finished, it doesn't wait, of course, and returns the |
1583 |
|
|
data: |
1584 |
|
|
|
1585 |
root |
1.118 |
$txn->{finished}->recv; |
1586 |
root |
1.6 |
return $txn->{result}; |
1587 |
root |
1.5 |
|
1588 |
|
|
The actual code goes further and collects all errors (C<die>s, exceptions) |
1589 |
root |
1.128 |
that occurred during request processing. The C<result> method detects |
1590 |
root |
1.52 |
whether an exception as thrown (it is stored inside the $txn object) |
1591 |
root |
1.5 |
and just throws the exception, which means connection errors and other |
1592 |
|
|
problems get reported tot he code that tries to use the result, not in a |
1593 |
|
|
random callback. |
1594 |
|
|
|
1595 |
|
|
All of this enables the following usage styles: |
1596 |
|
|
|
1597 |
|
|
1. Blocking: |
1598 |
|
|
|
1599 |
|
|
my $data = $fcp->client_get ($url); |
1600 |
|
|
|
1601 |
root |
1.49 |
2. Blocking, but running in parallel: |
1602 |
root |
1.5 |
|
1603 |
|
|
my @datas = map $_->result, |
1604 |
|
|
map $fcp->txn_client_get ($_), |
1605 |
|
|
@urls; |
1606 |
|
|
|
1607 |
|
|
Both blocking examples work without the module user having to know |
1608 |
|
|
anything about events. |
1609 |
|
|
|
1610 |
root |
1.49 |
3a. Event-based in a main program, using any supported event module: |
1611 |
root |
1.5 |
|
1612 |
root |
1.49 |
use EV; |
1613 |
root |
1.5 |
|
1614 |
|
|
$fcp->txn_client_get ($url)->cb (sub { |
1615 |
|
|
my $txn = shift; |
1616 |
|
|
my $data = $txn->result; |
1617 |
|
|
... |
1618 |
|
|
}); |
1619 |
|
|
|
1620 |
root |
1.49 |
EV::loop; |
1621 |
root |
1.5 |
|
1622 |
|
|
3b. The module user could use AnyEvent, too: |
1623 |
|
|
|
1624 |
|
|
use AnyEvent; |
1625 |
|
|
|
1626 |
|
|
my $quit = AnyEvent->condvar; |
1627 |
|
|
|
1628 |
|
|
$fcp->txn_client_get ($url)->cb (sub { |
1629 |
|
|
... |
1630 |
root |
1.118 |
$quit->send; |
1631 |
root |
1.5 |
}); |
1632 |
|
|
|
1633 |
root |
1.118 |
$quit->recv; |
1634 |
root |
1.5 |
|
1635 |
root |
1.64 |
|
1636 |
root |
1.91 |
=head1 BENCHMARKS |
1637 |
root |
1.64 |
|
1638 |
root |
1.65 |
To give you an idea of the performance and overheads that AnyEvent adds |
1639 |
root |
1.91 |
over the event loops themselves and to give you an impression of the speed |
1640 |
|
|
of various event loops I prepared some benchmarks. |
1641 |
root |
1.77 |
|
1642 |
root |
1.91 |
=head2 BENCHMARKING ANYEVENT OVERHEAD |
1643 |
|
|
|
1644 |
|
|
Here is a benchmark of various supported event models used natively and |
1645 |
root |
1.128 |
through AnyEvent. The benchmark creates a lot of timers (with a zero |
1646 |
root |
1.91 |
timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1647 |
|
|
which it is), lets them fire exactly once and destroys them again. |
1648 |
|
|
|
1649 |
|
|
Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
1650 |
|
|
distribution. |
1651 |
|
|
|
1652 |
|
|
=head3 Explanation of the columns |
1653 |
root |
1.68 |
|
1654 |
|
|
I<watcher> is the number of event watchers created/destroyed. Since |
1655 |
|
|
different event models feature vastly different performances, each event |
1656 |
|
|
loop was given a number of watchers so that overall runtime is acceptable |
1657 |
|
|
and similar between tested event loop (and keep them from crashing): Glib |
1658 |
|
|
would probably take thousands of years if asked to process the same number |
1659 |
|
|
of watchers as EV in this benchmark. |
1660 |
|
|
|
1661 |
|
|
I<bytes> is the number of bytes (as measured by the resident set size, |
1662 |
|
|
RSS) consumed by each watcher. This method of measuring captures both C |
1663 |
|
|
and Perl-based overheads. |
1664 |
|
|
|
1665 |
|
|
I<create> is the time, in microseconds (millionths of seconds), that it |
1666 |
|
|
takes to create a single watcher. The callback is a closure shared between |
1667 |
|
|
all watchers, to avoid adding memory overhead. That means closure creation |
1668 |
|
|
and memory usage is not included in the figures. |
1669 |
|
|
|
1670 |
|
|
I<invoke> is the time, in microseconds, used to invoke a simple |
1671 |
|
|
callback. The callback simply counts down a Perl variable and after it was |
1672 |
root |
1.118 |
invoked "watcher" times, it would C<< ->send >> a condvar once to |
1673 |
root |
1.69 |
signal the end of this phase. |
1674 |
root |
1.64 |
|
1675 |
root |
1.71 |
I<destroy> is the time, in microseconds, that it takes to destroy a single |
1676 |
root |
1.68 |
watcher. |
1677 |
root |
1.64 |
|
1678 |
root |
1.91 |
=head3 Results |
1679 |
root |
1.64 |
|
1680 |
root |
1.75 |
name watchers bytes create invoke destroy comment |
1681 |
root |
1.187 |
EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
1682 |
|
|
EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1683 |
|
|
CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1684 |
root |
1.190 |
Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1685 |
root |
1.186 |
Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1686 |
|
|
Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1687 |
|
|
Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1688 |
|
|
Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1689 |
|
|
POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1690 |
|
|
POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1691 |
root |
1.64 |
|
1692 |
root |
1.91 |
=head3 Discussion |
1693 |
root |
1.68 |
|
1694 |
|
|
The benchmark does I<not> measure scalability of the event loop very |
1695 |
|
|
well. For example, a select-based event loop (such as the pure perl one) |
1696 |
|
|
can never compete with an event loop that uses epoll when the number of |
1697 |
root |
1.80 |
file descriptors grows high. In this benchmark, all events become ready at |
1698 |
|
|
the same time, so select/poll-based implementations get an unnatural speed |
1699 |
|
|
boost. |
1700 |
root |
1.68 |
|
1701 |
root |
1.95 |
Also, note that the number of watchers usually has a nonlinear effect on |
1702 |
|
|
overall speed, that is, creating twice as many watchers doesn't take twice |
1703 |
|
|
the time - usually it takes longer. This puts event loops tested with a |
1704 |
|
|
higher number of watchers at a disadvantage. |
1705 |
|
|
|
1706 |
root |
1.96 |
To put the range of results into perspective, consider that on the |
1707 |
|
|
benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1708 |
|
|
EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
1709 |
|
|
cycles with POE. |
1710 |
|
|
|
1711 |
root |
1.68 |
C<EV> is the sole leader regarding speed and memory use, which are both |
1712 |
root |
1.84 |
maximal/minimal, respectively. Even when going through AnyEvent, it uses |
1713 |
|
|
far less memory than any other event loop and is still faster than Event |
1714 |
|
|
natively. |
1715 |
root |
1.64 |
|
1716 |
|
|
The pure perl implementation is hit in a few sweet spots (both the |
1717 |
root |
1.86 |
constant timeout and the use of a single fd hit optimisations in the perl |
1718 |
|
|
interpreter and the backend itself). Nevertheless this shows that it |
1719 |
|
|
adds very little overhead in itself. Like any select-based backend its |
1720 |
|
|
performance becomes really bad with lots of file descriptors (and few of |
1721 |
|
|
them active), of course, but this was not subject of this benchmark. |
1722 |
root |
1.64 |
|
1723 |
root |
1.90 |
The C<Event> module has a relatively high setup and callback invocation |
1724 |
|
|
cost, but overall scores in on the third place. |
1725 |
root |
1.64 |
|
1726 |
root |
1.90 |
C<Glib>'s memory usage is quite a bit higher, but it features a |
1727 |
root |
1.73 |
faster callback invocation and overall ends up in the same class as |
1728 |
|
|
C<Event>. However, Glib scales extremely badly, doubling the number of |
1729 |
|
|
watchers increases the processing time by more than a factor of four, |
1730 |
|
|
making it completely unusable when using larger numbers of watchers |
1731 |
|
|
(note that only a single file descriptor was used in the benchmark, so |
1732 |
|
|
inefficiencies of C<poll> do not account for this). |
1733 |
root |
1.64 |
|
1734 |
root |
1.73 |
The C<Tk> adaptor works relatively well. The fact that it crashes with |
1735 |
root |
1.64 |
more than 2000 watchers is a big setback, however, as correctness takes |
1736 |
root |
1.68 |
precedence over speed. Nevertheless, its performance is surprising, as the |
1737 |
|
|
file descriptor is dup()ed for each watcher. This shows that the dup() |
1738 |
|
|
employed by some adaptors is not a big performance issue (it does incur a |
1739 |
root |
1.87 |
hidden memory cost inside the kernel which is not reflected in the figures |
1740 |
|
|
above). |
1741 |
root |
1.68 |
|
1742 |
root |
1.103 |
C<POE>, regardless of underlying event loop (whether using its pure perl |
1743 |
|
|
select-based backend or the Event module, the POE-EV backend couldn't |
1744 |
|
|
be tested because it wasn't working) shows abysmal performance and |
1745 |
|
|
memory usage with AnyEvent: Watchers use almost 30 times as much memory |
1746 |
|
|
as EV watchers, and 10 times as much memory as Event (the high memory |
1747 |
root |
1.87 |
requirements are caused by requiring a session for each watcher). Watcher |
1748 |
|
|
invocation speed is almost 900 times slower than with AnyEvent's pure perl |
1749 |
root |
1.103 |
implementation. |
1750 |
|
|
|
1751 |
|
|
The design of the POE adaptor class in AnyEvent can not really account |
1752 |
|
|
for the performance issues, though, as session creation overhead is |
1753 |
|
|
small compared to execution of the state machine, which is coded pretty |
1754 |
|
|
optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
1755 |
|
|
using multiple sessions is not a good approach, especially regarding |
1756 |
|
|
memory usage, even the author of POE could not come up with a faster |
1757 |
|
|
design). |
1758 |
root |
1.72 |
|
1759 |
root |
1.91 |
=head3 Summary |
1760 |
root |
1.72 |
|
1761 |
root |
1.87 |
=over 4 |
1762 |
|
|
|
1763 |
root |
1.89 |
=item * Using EV through AnyEvent is faster than any other event loop |
1764 |
|
|
(even when used without AnyEvent), but most event loops have acceptable |
1765 |
|
|
performance with or without AnyEvent. |
1766 |
root |
1.72 |
|
1767 |
root |
1.87 |
=item * The overhead AnyEvent adds is usually much smaller than the overhead of |
1768 |
root |
1.89 |
the actual event loop, only with extremely fast event loops such as EV |
1769 |
root |
1.73 |
adds AnyEvent significant overhead. |
1770 |
root |
1.72 |
|
1771 |
root |
1.90 |
=item * You should avoid POE like the plague if you want performance or |
1772 |
root |
1.72 |
reasonable memory usage. |
1773 |
root |
1.64 |
|
1774 |
root |
1.87 |
=back |
1775 |
|
|
|
1776 |
root |
1.91 |
=head2 BENCHMARKING THE LARGE SERVER CASE |
1777 |
|
|
|
1778 |
root |
1.128 |
This benchmark actually benchmarks the event loop itself. It works by |
1779 |
|
|
creating a number of "servers": each server consists of a socket pair, a |
1780 |
root |
1.91 |
timeout watcher that gets reset on activity (but never fires), and an I/O |
1781 |
|
|
watcher waiting for input on one side of the socket. Each time the socket |
1782 |
|
|
watcher reads a byte it will write that byte to a random other "server". |
1783 |
|
|
|
1784 |
|
|
The effect is that there will be a lot of I/O watchers, only part of which |
1785 |
|
|
are active at any one point (so there is a constant number of active |
1786 |
root |
1.128 |
fds for each loop iteration, but which fds these are is random). The |
1787 |
root |
1.91 |
timeout is reset each time something is read because that reflects how |
1788 |
|
|
most timeouts work (and puts extra pressure on the event loops). |
1789 |
|
|
|
1790 |
root |
1.128 |
In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
1791 |
root |
1.91 |
(1%) are active. This mirrors the activity of large servers with many |
1792 |
root |
1.92 |
connections, most of which are idle at any one point in time. |
1793 |
root |
1.91 |
|
1794 |
|
|
Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
1795 |
|
|
distribution. |
1796 |
|
|
|
1797 |
|
|
=head3 Explanation of the columns |
1798 |
|
|
|
1799 |
|
|
I<sockets> is the number of sockets, and twice the number of "servers" (as |
1800 |
root |
1.94 |
each server has a read and write socket end). |
1801 |
root |
1.91 |
|
1802 |
root |
1.128 |
I<create> is the time it takes to create a socket pair (which is |
1803 |
root |
1.91 |
nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
1804 |
|
|
|
1805 |
|
|
I<request>, the most important value, is the time it takes to handle a |
1806 |
|
|
single "request", that is, reading the token from the pipe and forwarding |
1807 |
root |
1.93 |
it to another server. This includes deleting the old timeout and creating |
1808 |
|
|
a new one that moves the timeout into the future. |
1809 |
root |
1.91 |
|
1810 |
|
|
=head3 Results |
1811 |
|
|
|
1812 |
|
|
name sockets create request |
1813 |
|
|
EV 20000 69.01 11.16 |
1814 |
root |
1.99 |
Perl 20000 73.32 35.87 |
1815 |
root |
1.91 |
Event 20000 212.62 257.32 |
1816 |
|
|
Glib 20000 651.16 1896.30 |
1817 |
|
|
POE 20000 349.67 12317.24 uses POE::Loop::Event |
1818 |
|
|
|
1819 |
|
|
=head3 Discussion |
1820 |
|
|
|
1821 |
|
|
This benchmark I<does> measure scalability and overall performance of the |
1822 |
|
|
particular event loop. |
1823 |
|
|
|
1824 |
|
|
EV is again fastest. Since it is using epoll on my system, the setup time |
1825 |
|
|
is relatively high, though. |
1826 |
|
|
|
1827 |
|
|
Perl surprisingly comes second. It is much faster than the C-based event |
1828 |
|
|
loops Event and Glib. |
1829 |
|
|
|
1830 |
|
|
Event suffers from high setup time as well (look at its code and you will |
1831 |
|
|
understand why). Callback invocation also has a high overhead compared to |
1832 |
|
|
the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
1833 |
|
|
uses select or poll in basically all documented configurations. |
1834 |
|
|
|
1835 |
|
|
Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
1836 |
|
|
clearly fails to perform with many filehandles or in busy servers. |
1837 |
|
|
|
1838 |
|
|
POE is still completely out of the picture, taking over 1000 times as long |
1839 |
|
|
as EV, and over 100 times as long as the Perl implementation, even though |
1840 |
|
|
it uses a C-based event loop in this case. |
1841 |
|
|
|
1842 |
|
|
=head3 Summary |
1843 |
|
|
|
1844 |
|
|
=over 4 |
1845 |
|
|
|
1846 |
root |
1.103 |
=item * The pure perl implementation performs extremely well. |
1847 |
root |
1.91 |
|
1848 |
|
|
=item * Avoid Glib or POE in large projects where performance matters. |
1849 |
|
|
|
1850 |
|
|
=back |
1851 |
|
|
|
1852 |
|
|
=head2 BENCHMARKING SMALL SERVERS |
1853 |
|
|
|
1854 |
|
|
While event loops should scale (and select-based ones do not...) even to |
1855 |
|
|
large servers, most programs we (or I :) actually write have only a few |
1856 |
|
|
I/O watchers. |
1857 |
|
|
|
1858 |
|
|
In this benchmark, I use the same benchmark program as in the large server |
1859 |
|
|
case, but it uses only eight "servers", of which three are active at any |
1860 |
|
|
one time. This should reflect performance for a small server relatively |
1861 |
|
|
well. |
1862 |
|
|
|
1863 |
|
|
The columns are identical to the previous table. |
1864 |
|
|
|
1865 |
|
|
=head3 Results |
1866 |
|
|
|
1867 |
|
|
name sockets create request |
1868 |
|
|
EV 16 20.00 6.54 |
1869 |
root |
1.99 |
Perl 16 25.75 12.62 |
1870 |
root |
1.91 |
Event 16 81.27 35.86 |
1871 |
|
|
Glib 16 32.63 15.48 |
1872 |
|
|
POE 16 261.87 276.28 uses POE::Loop::Event |
1873 |
|
|
|
1874 |
|
|
=head3 Discussion |
1875 |
|
|
|
1876 |
|
|
The benchmark tries to test the performance of a typical small |
1877 |
|
|
server. While knowing how various event loops perform is interesting, keep |
1878 |
|
|
in mind that their overhead in this case is usually not as important, due |
1879 |
root |
1.97 |
to the small absolute number of watchers (that is, you need efficiency and |
1880 |
|
|
speed most when you have lots of watchers, not when you only have a few of |
1881 |
|
|
them). |
1882 |
root |
1.91 |
|
1883 |
|
|
EV is again fastest. |
1884 |
|
|
|
1885 |
elmex |
1.129 |
Perl again comes second. It is noticeably faster than the C-based event |
1886 |
root |
1.102 |
loops Event and Glib, although the difference is too small to really |
1887 |
|
|
matter. |
1888 |
root |
1.91 |
|
1889 |
root |
1.97 |
POE also performs much better in this case, but is is still far behind the |
1890 |
root |
1.91 |
others. |
1891 |
|
|
|
1892 |
|
|
=head3 Summary |
1893 |
|
|
|
1894 |
|
|
=over 4 |
1895 |
|
|
|
1896 |
|
|
=item * C-based event loops perform very well with small number of |
1897 |
|
|
watchers, as the management overhead dominates. |
1898 |
|
|
|
1899 |
|
|
=back |
1900 |
|
|
|
1901 |
root |
1.64 |
|
1902 |
root |
1.185 |
=head1 SIGNALS |
1903 |
|
|
|
1904 |
|
|
AnyEvent currently installs handlers for these signals: |
1905 |
|
|
|
1906 |
|
|
=over 4 |
1907 |
|
|
|
1908 |
|
|
=item SIGCHLD |
1909 |
|
|
|
1910 |
|
|
A handler for C<SIGCHLD> is installed by AnyEvent's child watcher |
1911 |
|
|
emulation for event loops that do not support them natively. Also, some |
1912 |
|
|
event loops install a similar handler. |
1913 |
|
|
|
1914 |
|
|
=item SIGPIPE |
1915 |
|
|
|
1916 |
|
|
A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> |
1917 |
|
|
when AnyEvent gets loaded. |
1918 |
|
|
|
1919 |
|
|
The rationale for this is that AnyEvent users usually do not really depend |
1920 |
|
|
on SIGPIPE delivery (which is purely an optimisation for shell use, or |
1921 |
|
|
badly-written programs), but C<SIGPIPE> can cause spurious and rare |
1922 |
|
|
program exits as a lot of people do not expect C<SIGPIPE> when writing to |
1923 |
|
|
some random socket. |
1924 |
|
|
|
1925 |
|
|
The rationale for installing a no-op handler as opposed to ignoring it is |
1926 |
|
|
that this way, the handler will be restored to defaults on exec. |
1927 |
|
|
|
1928 |
|
|
Feel free to install your own handler, or reset it to defaults. |
1929 |
|
|
|
1930 |
|
|
=back |
1931 |
|
|
|
1932 |
|
|
=cut |
1933 |
|
|
|
1934 |
|
|
$SIG{PIPE} = sub { } |
1935 |
|
|
unless defined $SIG{PIPE}; |
1936 |
|
|
|
1937 |
|
|
|
1938 |
root |
1.55 |
=head1 FORK |
1939 |
|
|
|
1940 |
|
|
Most event libraries are not fork-safe. The ones who are usually are |
1941 |
root |
1.104 |
because they rely on inefficient but fork-safe C<select> or C<poll> |
1942 |
|
|
calls. Only L<EV> is fully fork-aware. |
1943 |
root |
1.55 |
|
1944 |
|
|
If you have to fork, you must either do so I<before> creating your first |
1945 |
|
|
watcher OR you must not use AnyEvent at all in the child. |
1946 |
|
|
|
1947 |
root |
1.64 |
|
1948 |
root |
1.55 |
=head1 SECURITY CONSIDERATIONS |
1949 |
|
|
|
1950 |
|
|
AnyEvent can be forced to load any event model via |
1951 |
|
|
$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
1952 |
|
|
execute arbitrary code or directly gain access, it can easily be used to |
1953 |
|
|
make the program hang or malfunction in subtle ways, as AnyEvent watchers |
1954 |
|
|
will not be active when the program uses a different event model than |
1955 |
|
|
specified in the variable. |
1956 |
|
|
|
1957 |
|
|
You can make AnyEvent completely ignore this variable by deleting it |
1958 |
|
|
before the first watcher gets created, e.g. with a C<BEGIN> block: |
1959 |
|
|
|
1960 |
root |
1.151 |
BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1961 |
|
|
|
1962 |
|
|
use AnyEvent; |
1963 |
root |
1.55 |
|
1964 |
root |
1.107 |
Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1965 |
|
|
be used to probe what backend is used and gain other information (which is |
1966 |
root |
1.167 |
probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and |
1967 |
|
|
$ENV{PERL_ANYEGENT_STRICT}. |
1968 |
root |
1.107 |
|
1969 |
root |
1.64 |
|
1970 |
root |
1.156 |
=head1 BUGS |
1971 |
|
|
|
1972 |
|
|
Perl 5.8 has numerous memleaks that sometimes hit this module and are hard |
1973 |
|
|
to work around. If you suffer from memleaks, first upgrade to Perl 5.10 |
1974 |
|
|
and check wether the leaks still show up. (Perl 5.10.0 has other annoying |
1975 |
root |
1.197 |
memleaks, such as leaking on C<map> and C<grep> but it is usually not as |
1976 |
root |
1.156 |
pronounced). |
1977 |
|
|
|
1978 |
|
|
|
1979 |
root |
1.2 |
=head1 SEE ALSO |
1980 |
|
|
|
1981 |
root |
1.125 |
Utility functions: L<AnyEvent::Util>. |
1982 |
|
|
|
1983 |
root |
1.108 |
Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
1984 |
|
|
L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
1985 |
|
|
|
1986 |
|
|
Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
1987 |
|
|
L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
1988 |
|
|
L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
1989 |
|
|
L<AnyEvent::Impl::POE>. |
1990 |
|
|
|
1991 |
root |
1.125 |
Non-blocking file handles, sockets, TCP clients and |
1992 |
|
|
servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
1993 |
|
|
|
1994 |
root |
1.122 |
Asynchronous DNS: L<AnyEvent::DNS>. |
1995 |
|
|
|
1996 |
root |
1.108 |
Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
1997 |
root |
1.5 |
|
1998 |
root |
1.125 |
Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
1999 |
root |
1.2 |
|
2000 |
root |
1.64 |
|
2001 |
root |
1.54 |
=head1 AUTHOR |
2002 |
|
|
|
2003 |
root |
1.151 |
Marc Lehmann <schmorp@schmorp.de> |
2004 |
|
|
http://home.schmorp.de/ |
2005 |
root |
1.2 |
|
2006 |
|
|
=cut |
2007 |
|
|
|
2008 |
|
|
1 |
2009 |
root |
1.1 |
|