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=head1 NAME |
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|
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EV - perl interface to libev, a high performance full-featured event loop |
| 4 |
|
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=head1 SYNOPSIS |
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|
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use EV; |
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|
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# TIMERS |
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|
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my $w = EV::timer 2, 0, sub { |
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warn "is called after 2s"; |
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}; |
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|
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my $w = EV::timer 2, 1, sub { |
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warn "is called roughly every 2s (repeat = 1)"; |
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}; |
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|
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undef $w; # destroy event watcher again |
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|
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my $w = EV::periodic 0, 60, sub { |
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warn "is called every minute, on the minute, exactly"; |
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}; |
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|
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# IO |
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|
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my $w = EV::io *STDIN, EV::READ, sub { |
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my ($w, $revents) = @_; # all callbacks get the watcher object and event mask |
| 29 |
warn "stdin is readable, you entered: ", <STDIN>; |
| 30 |
}; |
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|
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# SIGNALS |
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|
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my $w = EV::signal 'QUIT', sub { |
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warn "sigquit received\n"; |
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}; |
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|
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my $w = EV::signal 3, sub { |
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warn "sigquit received (this is GNU/Linux, right?)\n"; |
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}; |
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|
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# CHILD/PID STATUS CHANGES |
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|
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my $w = EV::child 666, sub { |
| 45 |
my ($w, $revents, $status) = @_; |
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}; |
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|
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# MAINLOOP |
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EV::loop; # loop until EV::loop_done is called |
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EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
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EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
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|
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=head1 DESCRIPTION |
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|
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This module provides an interface to libev |
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(L<http://software.schmorp.de/pkg/libev.html>). |
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|
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=cut |
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|
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package EV; |
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|
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use strict; |
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|
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BEGIN { |
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our $VERSION = '0.1'; |
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use XSLoader; |
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XSLoader::load "EV", $VERSION; |
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} |
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|
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@EV::Io::ISA = |
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@EV::Timer::ISA = |
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@EV::Periodic::ISA = |
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@EV::Signal::ISA = |
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@EV::Idle::ISA = |
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@EV::Prepare::ISA = |
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@EV::Check::ISA = |
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@EV::Child::ISA = "EV::Watcher"; |
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|
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=head1 BASIC INTERFACE |
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|
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=over 4 |
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|
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=item $EV::DIED |
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|
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Must contain a reference to a function that is called when a callback |
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throws an exception (with $@ containing thr error). The default prints an |
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informative message and continues. |
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|
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If this callback throws an exception it will be silently ignored. |
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|
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=item $time = EV::time |
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|
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Returns the current time in (fractional) seconds since the epoch. |
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|
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=item $time = EV::now |
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|
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Returns the time the last event loop iteration has been started. This |
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is the time that (relative) timers are based on, and refering to it is |
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usually faster then calling EV::time. |
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|
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=item $method = EV::ev_method |
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|
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Returns an integer describing the backend used by libev (EV::METHOD_SELECT |
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or EV::METHOD_EPOLL). |
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|
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=item EV::loop [$flags] |
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|
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Begin checking for events and calling callbacks. It returns when a |
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callback calls EV::loop_done. |
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|
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The $flags argument can be one of the following: |
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|
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0 as above |
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EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
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EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
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|
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=item EV::loop_done [$how] |
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|
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When called with no arguments or an argument of 1, makes the innermost |
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call to EV::loop return. |
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|
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When called with an agrument of 2, all calls to EV::loop will return as |
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fast as possible. |
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|
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=back |
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|
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=head2 WATCHER |
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|
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A watcher is an object that gets created to record your interest in some |
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event. For instance, if you want to wait for STDIN to become readable, you |
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would create an EV::io watcher for that: |
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|
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my $watcher = EV::io *STDIN, EV::READ, sub { |
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my ($watcher, $revents) = @_; |
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warn "yeah, STDIN should not be readable without blocking!\n" |
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}; |
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|
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All watchers can be active (waiting for events) or inactive (paused). Only |
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active watchers will have their callbacks invoked. All callbacks will be |
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called with at least two arguments: the watcher and a bitmask of received |
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events. |
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|
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Each watcher type has its associated bit in revents, so you can use the |
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same callback for multiple watchers. The event mask is named after the |
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type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
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EV::periodic sets EV::PERIODIC and so on, with the exception of IO events |
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(which can set both EV::READ and EV::WRITE bits), and EV::timer (which |
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uses EV::TIMEOUT). |
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|
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In the rare case where one wants to create a watcher but not start it at |
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the same time, each constructor has a variant with a trailing C<_ns> in |
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its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. |
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|
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Please note that a watcher will automatically be stopped when the watcher |
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object is returned, so you I<need> to keep the watcher objects returned by |
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the constructors. |
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|
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=head2 WATCHER TYPES |
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|
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Now lets move to the existing watcher types and asociated methods. |
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|
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The following methods are available for all watchers. Then followes a |
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description of each watcher constructor (EV::io, EV::timer, EV::periodic, |
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EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by |
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any type-specific methods (if any). |
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|
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=over 4 |
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|
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=item $w->start |
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|
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Starts a watcher if it isn't active already. Does nothing to an already |
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active watcher. By default, all watchers start out in the active state |
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(see the description of the C<_ns> variants if you need stopped watchers). |
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|
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=item $w->stop |
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|
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Stop a watcher if it is active. Also clear any pending events (events that |
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have been received but that didn't yet result in a callback invocation), |
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regardless of wether the watcher was active or not. |
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|
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=item $bool = $w->is_active |
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|
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Returns true if the watcher is active, false otherwise. |
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|
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=item $current_cb = $w->cb |
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|
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=item $old_cb = $w->cb ($new_cb) |
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|
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Queries the callback on the watcher and optionally changes it. You cna do |
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this at any time. |
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|
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=item $w->trigger ($revents) |
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|
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Call the callback *now* with the given event mask. |
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|
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|
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=item $w = EV::io $fileno_or_fh, $eventmask, $callback |
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|
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=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
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|
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As long as the returned watcher object is alive, call the C<$callback> |
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when the events specified in C<$eventmask>. |
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|
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The $eventmask can be one or more of these constants ORed together: |
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|
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EV::READ wait until read() wouldn't block anymore |
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EV::WRITE wait until write() wouldn't block anymore |
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|
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The C<io_ns> variant doesn't start (activate) the newly created watcher. |
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|
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=item $w->set ($fileno_or_fh, $eventmask) |
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|
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Reconfigures the watcher, see the constructor above for details. Can be |
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called at any time. |
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|
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=item $current_fh = $w->fh |
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|
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=item $old_fh = $w->fh ($new_fh) |
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|
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Returns the previously set filehandle and optionally set a new one. |
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|
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=item $current_eventmask = $w->events |
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|
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=item $old_eventmask = $w->events ($new_eventmask) |
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|
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Returns the previously set event mask and optionally set a new one. |
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|
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|
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=item $w = EV::timer $after, $repeat, $callback |
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|
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=item $w = EV::timer_ns $after, $repeat, $callback |
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|
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Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, |
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the timer will be restarted (with the $repeat value as $after) after the |
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callback returns. |
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|
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This means that the callback would be called roughly after C<$after> |
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seconds, and then every C<$repeat> seconds. "Roughly" because the time of |
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callback processing is not taken into account, so the timer will slowly |
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drift. If that isn't acceptable, look at EV::periodic. |
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|
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The timer is based on a monotonic clock, that is if somebody is sitting |
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in front of the machine while the timer is running and changes the system |
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clock, the timer will nevertheless run (roughly) the same time. |
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|
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The C<timer_ns> variant doesn't start (activate) the newly created watcher. |
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|
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=item $w->set ($after, $repeat) |
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|
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Reconfigures the watcher, see the constructor above for details. Can be at |
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any time. |
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|
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=item $w->again |
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|
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Similar to the C<start> method, but has special semantics for repeating timers: |
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|
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If the timer is active and repeating, reset the timeout to occur |
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C<$repeat> seconds after now. |
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|
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If the timer is active and non-repeating, it will be stopped. |
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|
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If the timer is in active and repeating, start it. |
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|
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Otherwise do nothing. |
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|
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This behaviour is useful when you have a timeout for some IO |
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operation. You create a timer object with the same value for C<$after> and |
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C<$repeat>, and then, in the read/write watcher, run the C<again> method |
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on the timeout. |
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|
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|
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=item $w = EV::periodic $at, $interval, $callback |
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|
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=item $w = EV::periodic_ns $at, $interval, $callback |
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|
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Similar to EV::timer, but the time is given as an absolute point in time |
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(C<$at>), plus an optional C<$interval>. |
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|
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If the C<$interval> is zero, then the callback will be called at the time |
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C<$at> if that is in the future, or as soon as possible if it is in the |
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past. It will not automatically repeat. |
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|
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If the C<$interval> is nonzero, then the watcher will always be scheduled |
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to time out at the next C<$at + N * $interval> time. |
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|
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This can be used to schedule a callback to run at very regular intervals, |
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as long as the processing time is less then the interval (otherwise |
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obviously events will be skipped). |
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|
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Another way to think about it (for the mathematically inclined) is that |
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EV::periodic will try to run the callback at the next possible time where |
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C<$time = $at (mod $interval)>, regardless of any time jumps. |
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|
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This periodic timer is based on "wallclock time", that is, if the clock |
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changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at |
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the specified time. |
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|
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The C<periodic_ns> variant doesn't start (activate) the newly created watcher. |
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|
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=item $w->set ($at, $interval) |
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|
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Reconfigures the watcher, see the constructor above for details. Can be at |
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any time. |
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|
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|
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=item $w = EV::signal $signal, $callback |
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|
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=item $w = EV::signal_ns $signal, $callback |
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|
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Call the callback when $signal is received (the signal can be specified |
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by number or by name, just as with kill or %SIG). |
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|
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EV will grab the signal for the process (the kernel only allows one |
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component to receive a signal at a time) when you start a signal watcher, |
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and removes it again when you stop it. Perl does the same when you |
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add/remove callbacks to %SIG, so watch out. |
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|
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You can have as many signal watchers per signal as you want. |
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|
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The C<signal_ns> variant doesn't start (activate) the newly created watcher. |
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|
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=item $w->set ($signal) |
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|
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Reconfigures the watcher, see the constructor above for details. Can be at |
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any time. |
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|
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|
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=item $w = EV::child $pid, $callback |
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|
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=item $w = EV::child_ns $pid, $callback |
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|
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Call the callback when a status change for pid C<$pid> (or any pid |
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if C<$pid> is 0) has been received. More precisely: when the process |
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receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all |
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changed/zombie children and call the callback. |
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|
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Unlike all other callbacks, this callback will be called with an |
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additional third argument which is the exit status. See the C<waitpid> |
| 339 |
function for details. |
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|
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You can have as many pid watchers per pid as you want. |
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|
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The C<child_ns> variant doesn't start (activate) the newly created watcher. |
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|
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=item $w->set ($pid) |
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|
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Reconfigures the watcher, see the constructor above for details. Can be at |
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any time. |
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|
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|
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=item $w = EV::idle $callback |
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|
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=item $w = EV::idle_ns $callback |
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|
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Call the callback when there are no pending io, timer/periodic, signal or |
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child events, i.e. when the process is idle. |
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|
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The process will not block as long as any idle watchers are active, and |
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they will be called repeatedly until stopped. |
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|
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The C<idle_ns> variant doesn't start (activate) the newly created watcher. |
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|
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|
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=item $w = EV::prepare $callback |
| 365 |
|
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=item $w = EV::prepare_ns $callback |
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|
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Call the callback just before the process would block. You can still |
| 369 |
create/modify any watchers at this point. |
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|
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See the EV::check watcher, below, for explanations and an example. |
| 372 |
|
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The C<prepare_ns> variant doesn't start (activate) the newly created watcher. |
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|
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|
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=item $w = EV::check $callback |
| 377 |
|
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=item $w = EV::check_ns $callback |
| 379 |
|
| 380 |
Call the callback just after the process wakes up again (after it has |
| 381 |
gathered events), but before any other callbacks have been invoked. |
| 382 |
|
| 383 |
This is used to integrate other event-based software into the EV |
| 384 |
mainloop: You register a prepare callback and in there, you create io and |
| 385 |
timer watchers as required by the other software. Here is a real-world |
| 386 |
example of integrating Net::SNMP (with some details left out): |
| 387 |
|
| 388 |
our @snmp_watcher; |
| 389 |
|
| 390 |
our $snmp_prepare = EV::prepare sub { |
| 391 |
# do nothing unless active |
| 392 |
$dispatcher->{_event_queue_h} |
| 393 |
or return; |
| 394 |
|
| 395 |
# make the dispatcher handle any outstanding stuff |
| 396 |
|
| 397 |
# create an IO watcher for each and every socket |
| 398 |
@snmp_watcher = ( |
| 399 |
(map { EV::io $_, EV::READ, sub { } } |
| 400 |
keys %{ $dispatcher->{_descriptors} }), |
| 401 |
); |
| 402 |
|
| 403 |
# if there are any timeouts, also create a timer |
| 404 |
push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { } |
| 405 |
if $event->[Net::SNMP::Dispatcher::_ACTIVE]; |
| 406 |
}; |
| 407 |
|
| 408 |
The callbacks are irrelevant, the only purpose of those watchers is |
| 409 |
to wake up the process as soon as one of those events occurs (socket |
| 410 |
readable, or timer timed out). The corresponding EV::check watcher will then |
| 411 |
clean up: |
| 412 |
|
| 413 |
our $snmp_check = EV::check sub { |
| 414 |
# destroy all watchers |
| 415 |
@snmp_watcher = (); |
| 416 |
|
| 417 |
# make the dispatcher handle any new stuff |
| 418 |
}; |
| 419 |
|
| 420 |
The callbacks of the created watchers will not be called as the watchers |
| 421 |
are destroyed before this cna happen (remember EV::check gets called |
| 422 |
first). |
| 423 |
|
| 424 |
The C<check_ns> variant doesn't start (activate) the newly created watcher. |
| 425 |
|
| 426 |
=back |
| 427 |
|
| 428 |
=head1 THREADS |
| 429 |
|
| 430 |
Threads are not supported by this in any way. Perl pseudo-threads is evil |
| 431 |
stuff and must die. |
| 432 |
|
| 433 |
=cut |
| 434 |
|
| 435 |
our $DIED = sub { |
| 436 |
warn "EV: error in callback (ignoring): $@"; |
| 437 |
}; |
| 438 |
|
| 439 |
init; |
| 440 |
|
| 441 |
push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"]; |
| 442 |
|
| 443 |
1; |
| 444 |
|
| 445 |
=head1 SEE ALSO |
| 446 |
|
| 447 |
L<EV::DNS>, L<EV::AnyEvent>. |
| 448 |
|
| 449 |
=head1 AUTHOR |
| 450 |
|
| 451 |
Marc Lehmann <schmorp@schmorp.de> |
| 452 |
http://home.schmorp.de/ |
| 453 |
|
| 454 |
=cut |
| 455 |
|
