NAME

       AnyEvent::Loop - AnyEvent's Pure-Perl event loop

SYNOPSIS

          use AnyEvent;
          # use AnyEvent::Loop;

          # this module gets loaded automatically when no other loop can be found

          # Explicit use:
          use AnyEvent::Loop;
          use AnyEvent;

          ...

          AnyEvent::Loop::run; # run the event loop

DESCRIPTION

       This module provides an event loop for AnyEvent in case no other event loop could be found
       or loaded. You don't have to do anything to make it work with AnyEvent except by possibly
       loading it before creating the first AnyEvent watcher.

       This module is not some loop abstracion used by AnyEvent, but just another event loop like
       EV or Glib, just written in pure perl and delivered with AnyEvent, so AnyEvent always
       works, even in the absence of any other backend.

       If you want to use this module instead of autoloading a potentially better event loop you
       can simply load it (and no other event loops) before creating the first watcher.

       As for performance, this module is on par with (and usually faster than) most
       select/poll-based C event modules such as Event or Glib (it does not even come close to
       EV, though), with respect to I/O watchers. Timers are handled less optimally, but for many
       common tasks, it is still on par with event loops written in C.

       This event loop has been optimised for the following use cases:

       monotonic clock is available
           This module will use the POSIX monotonic clock option (if it can be detected at
           runtime) or the POSIX "times" function (if the resolution is at least 100Hz), in which
           case it will not suffer adversely from time jumps.

           If no monotonic clock is available, this module will not attempt to correct for time
           jumps in any way.

           The clock chosen will be reported if the environment variable $PERL_ANYEVENT_VERBOSE
           is set to 8 or higher.

       any number of watchers on one fd
           Supporting a large number of watchers per fd is purely a dirty benchmark optimisation
           not relevant in practise. The more common case of having one watcher per fd/poll combo
           is special-cased, however, and therefore fast, too.

       relatively few active fds per "select" call
           This module expects that only a tiny amount of fds is active at any one time. This is
           relatively typical of larger servers (but not the case where "select" traditionally is
           fast), at the expense of the "dense activity case" where most of the fds are active
           (which suits "select").

           The optimal implementation of the "dense" case is not much faster, though, so the
           module should behave very well in most cases, subject to the bad scalability of
           "select" in the presence of a large number of inactive file descriptors.

       lots of timer changes/iteration, or none at all
           This module sorts the timer list using perl's "sort", even though a total ordering is
           not required for timers internally.

           This sorting is expensive, but means sorting can be avoided unless the timer list has
           changed in a way that requires a new sort.

           This means that adding lots of timers is very efficient, as well as not changing the
           timers. Advancing timers (e.g. recreating a timeout watcher on activity) is also
           relatively efficient, for example, if you have a large number of timeout watchers that
           time out after 10 seconds, then the timer list will be sorted only once every 10
           seconds.

           This should not have much of an impact unless you have hundreds or thousands of
           timers, though, or your timers have very small timeouts.

FUNCTIONS

       The only user-visible functions provided by this module loop related - watchers are
       created via the normal AnyEvent mechanisms.

       AnyEvent::Loop::run
           Run the event loop, usually the last thing done in the main program when you want to
           use the pure-perl backend.

       AnyEvent::Loop::one_event
           Blocks until at least one new event has been received by the operating system, whether
           or not it was AnyEvent-related.

SEE ALSO

       AnyEvent.

AUTHOR

          Marc Lehmann <schmorp@schmorp.de>
          http://anyevent.schmorp.de