--- AnyEvent/lib/AnyEvent.pm 2008/05/24 15:19:30 1.129 +++ AnyEvent/lib/AnyEvent.pm 2008/07/08 23:53:37 1.168 @@ -1,4 +1,4 @@ -=head1 => NAME +=head1 NAME AnyEvent - provide framework for multiple event loops @@ -20,6 +20,12 @@ $w->send; # wake up current and all future recv's $w->recv; # enters "main loop" till $condvar gets ->send +=head1 INTRODUCTION/TUTORIAL + +This manpage is mainly a reference manual. If you are interested +in a tutorial or some gentle introduction, have a look at the +L manpage. + =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) Glib, POE, IO::Async, Event... CPAN offers event models by the dozen @@ -29,11 +35,12 @@ policy> and AnyEvent is I. First and foremost, I itself, it only -interfaces to whatever event model the main program happens to use in a +interfaces to whatever event model the main program happens to use, in a pragmatic way. For event models and certain classes of immortals alike, the statement "there can only be one" is a bitter reality: In general, only one event loop can be active at the same time in a process. AnyEvent -helps hiding the differences between those event loops. +cannot change this, but it can hide the differences between those event +loops. The goal of AnyEvent is to offer module authors the ability to do event programming (waiting for I/O or timer events) without subscribing to a @@ -44,18 +51,18 @@ For modules like POE or IO::Async (which is a total misnomer as it is actually doing all I/O I...), using them in your module is like joining a cult: After you joined, you are dependent on them and you -cannot use anything else, as it is simply incompatible to everything that -isn't itself. What's worse, all the potential users of your module are -I forced to use the same event loop you use. +cannot use anything else, as they are simply incompatible to everything +that isn't them. What's worse, all the potential users of your +module are I forced to use the same event loop you use. AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk works fine etc. etc. but none of these work together -with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if +with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your module uses one of those, every user of your module has to use it, too. But if your module uses AnyEvent, it works transparently with all -event models it supports (including stuff like POE and IO::Async, as long -as those use one of the supported event loops. It is trivial to add new -event loops to AnyEvent, too, so it is future-proof). +event models it supports (including stuff like IO::Async, as long as those +use one of the supported event loops. It is trivial to add new event loops +to AnyEvent, too, so it is future-proof). In addition to being free of having to use I, AnyEvent also is free of bloat and policy: with POE or similar @@ -64,7 +71,13 @@ offering the functionality that is necessary, in as thin as a wrapper as technically possible. -Of course, if you want lots of policy (this can arguably be somewhat +Of course, AnyEvent comes with a big (and fully optional!) toolbox +of useful functionality, such as an asynchronous DNS resolver, 100% +non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms +such as Windows) and lots of real-world knowledge and workarounds for +platform bugs and differences. + +Now, if you I lots of policy (this can arguably be somewhat useful) and you want to force your users to use the one and only event model, you should I use this module. @@ -104,7 +117,7 @@ The pure-perl implementation of AnyEvent is called C. Like other event modules you can load it -explicitly. +explicitly and enjoy the high availability of that event loop :) =head1 WATCHERS @@ -128,10 +141,10 @@ An any way to achieve that is this pattern: - my $w; $w = AnyEvent->type (arg => value ..., cb => sub { - # you can use $w here, for example to undef it - undef $w; - }); + my $w; $w = AnyEvent->type (arg => value ..., cb => sub { + # you can use $w here, for example to undef it + undef $w; + }); Note that C combination. This is necessary because in Perl, my variables are only visible after the statement in which they are @@ -142,11 +155,11 @@ You can create an I/O watcher by calling the C<< AnyEvent->io >> method with the following mandatory key-value pairs as arguments: -C the Perl I (I file descriptor) to watch -for events. C must be a string that is either C or C, -which creates a watcher waiting for "r"eadable or "w"ritable events, -respectively. C is the callback to invoke each time the file handle -becomes ready. +C the Perl I (I file descriptor) to watch for events +(AnyEvent might or might not keep a reference to this file handle). C +must be a string that is either C or C, which creates a watcher +waiting for "r"eadable or "w"ritable events, respectively. C is the +callback to invoke each time the file handle becomes ready. Although the callback might get passed parameters, their value and presence is undefined and you cannot rely on them. Portable AnyEvent @@ -160,9 +173,9 @@ always use non-blocking calls when reading/writing from/to your file handles. -Example: +Example: wait for readability of STDIN, then read a line and disable the +watcher. - # wait for readability of STDIN, then read a line and disable the watcher my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { chomp (my $input = ); warn "read: $input\n"; @@ -182,13 +195,18 @@ presence is undefined and you cannot rely on them. Portable AnyEvent callbacks cannot use arguments passed to time watcher callbacks. -The timer callback will be invoked at most once: if you want a repeating -timer you have to create a new watcher (this is a limitation by both Tk -and Glib). +The callback will normally be invoked once only. If you specify another +parameter, C, as a strictly positive number (> 0), then the +callback will be invoked regularly at that interval (in fractional +seconds) after the first invocation. If C is specified with a +false value, then it is treated as if it were missing. + +The callback will be rescheduled before invoking the callback, but no +attempt is done to avoid timer drift in most backends, so the interval is +only approximate. -Example: +Example: fire an event after 7.7 seconds. - # fire an event after 7.7 seconds my $w = AnyEvent->timer (after => 7.7, cb => sub { warn "timeout\n"; }); @@ -196,19 +214,12 @@ # to cancel the timer: undef $w; -Example 2: - - # fire an event after 0.5 seconds, then roughly every second - my $w; +Example 2: fire an event after 0.5 seconds, then roughly every second. - my $cb = sub { - # cancel the old timer while creating a new one - $w = AnyEvent->timer (after => 1, cb => $cb); + my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { + warn "timeout\n"; }; - # start the "loop" by creating the first watcher - $w = AnyEvent->timer (after => 0.5, cb => $cb); - =head3 TIMING ISSUES There are two ways to handle timers: based on real time (relative, "fire @@ -229,11 +240,74 @@ AnyEvent always prefers relative timers, if available, matching the AnyEvent API. +AnyEvent has two additional methods that return the "current time": + +=over 4 + +=item AnyEvent->time + +This returns the "current wallclock time" as a fractional number of +seconds since the Epoch (the same thing as C