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1.1 |
=head1 NAME |
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1.20 |
EV - perl interface to libev, a high performance full-featured event loop |
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1.1 |
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=head1 SYNOPSIS |
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1.11 |
use EV; |
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# TIMERS |
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1.11 |
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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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my $w = EV::timer 2, 2, sub { |
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warn "is called roughly every 2s (repeat = 2)"; |
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}; |
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undef $w; # destroy event watcher again |
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my $w = EV::periodic 0, 60, 0, sub { |
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warn "is called every minute, on the minute, exactly"; |
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}; |
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# IO |
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my $w = EV::io *STDIN, EV::READ, sub { |
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my ($w, $revents) = @_; # all callbacks receive the watcher and event mask |
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warn "stdin is readable, you entered: ", <STDIN>; |
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}; |
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# SIGNALS |
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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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# CHILD/PID STATUS CHANGES |
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my $w = EV::child 666, sub { |
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my ($w, $revents) = @_; |
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my $status = $w->rstatus; |
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}; |
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# STAT CHANGES |
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my $w = EV::stat "/etc/passwd", 10, sub { |
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my ($w, $revents) = @_; |
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warn $w->path, " has changed somehow.\n"; |
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}; |
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|
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# MAINLOOP |
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EV::loop; # loop until EV::unloop is called or all watchers stop |
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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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1.2 |
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1.1 |
=head1 DESCRIPTION |
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This module provides an interface to libev |
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(L<http://software.schmorp.de/pkg/libev.html>). While the documentation |
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below is comprehensive, one might also consult the documentation of libev |
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itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on |
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watcher semantics or some discussion on the available backends, or how to |
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force a specific backend with C<LIBEV_FLAGS>, or just about in any case |
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because it has much more detailed information. |
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=cut |
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package EV; |
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use strict; |
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BEGIN { |
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our $VERSION = '1.72'; |
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1.1 |
use XSLoader; |
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XSLoader::load "EV", $VERSION; |
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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::Child::ISA = |
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@EV::Stat::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::Embed::ISA = |
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@EV::Fork::ISA = |
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"EV::Watcher"; |
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|
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1.8 |
=head1 BASIC INTERFACE |
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|
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=over 4 |
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=item $EV::DIED |
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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 the error). The default prints an |
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informative message and continues. |
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If this callback throws an exception it will be silently ignored. |
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=item $time = EV::time |
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Returns the current time in (fractional) seconds since the epoch. |
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=item $time = EV::now |
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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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=item $method = EV::method |
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Returns an integer describing the backend used by libev (EV::METHOD_SELECT |
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or EV::METHOD_EPOLL). |
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=item EV::loop [$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::unloop. |
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|
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The $flags argument can be one of the following: |
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|
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0 as above |
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EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
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EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
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|
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=item EV::unloop [$how] |
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|
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When called with no arguments or an argument of EV::UNLOOP_ONE, makes the |
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innermost call to EV::loop return. |
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When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as |
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fast as possible. |
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|
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=item $count = EV::loop_count |
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Return the number of times the event loop has polled for new |
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events. Sometiems useful as a generation counter. |
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=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) |
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This function rolls together an I/O and a timer watcher for a single |
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one-shot event without the need for managing a watcher object. |
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If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events> |
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must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ |
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| EV::WRITE>, indicating the type of I/O event you want to wait for. If |
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you do not want to wait for some I/O event, specify C<undef> for |
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C<$fh_or_undef> and C<0> for C<$events>). |
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If timeout is C<undef> or negative, then there will be no |
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timeout. Otherwise a EV::timer with this value will be started. |
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When an error occurs or either the timeout or I/O watcher triggers, then |
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the callback will be called with the received event set (in general |
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you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>, |
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C<EV::WRITE> and C<EV::TIMEOUT>). |
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EV::once doesn't return anything: the watchers stay active till either |
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of them triggers, then they will be stopped and freed, and the callback |
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invoked. |
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=item EV::feed_fd_event ($fd, $revents) |
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Feed an event on a file descriptor into EV. EV will react to this call as |
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if the readyness notifications specified by C<$revents> (a combination of |
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C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>. |
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=item EV::feed_signal_event ($signal) |
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Feed a signal event into EV. EV will react to this call as if the signal |
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specified by C<$signal> had occured. |
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1.20 |
=back |
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1.65 |
|
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1.54 |
=head2 WATCHER OBJECTS |
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1.2 |
|
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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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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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1.2 |
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1.20 |
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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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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1.62 |
EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events |
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1.20 |
(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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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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Please note that a watcher will automatically be stopped when the watcher |
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1.23 |
object is destroyed, so you I<need> to keep the watcher objects returned by |
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1.20 |
the constructors. |
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1.23 |
Also, all methods changing some aspect of a watcher (->set, ->priority, |
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->fh and so on) automatically stop and start it again if it is active, |
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which means pending events get lost. |
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1.54 |
=head2 COMMON WATCHER METHODS |
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1.20 |
|
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1.54 |
This section lists methods common to all watchers. |
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1.20 |
|
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=over 4 |
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1.2 |
|
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1.20 |
=item $w->start |
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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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=item $w->stop |
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1.2 |
|
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1.20 |
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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1.62 |
regardless of whether the watcher was active or not. |
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1.2 |
|
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1.20 |
=item $bool = $w->is_active |
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1.2 |
|
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1.20 |
Returns true if the watcher is active, false otherwise. |
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1.30 |
=item $current_data = $w->data |
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=item $old_data = $w->data ($new_data) |
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Queries a freely usable data scalar on the watcher and optionally changes |
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it. This is a way to associate custom data with a watcher: |
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my $w = EV::timer 60, 0, sub { |
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warn $_[0]->data; |
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}; |
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$w->data ("print me!"); |
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1.20 |
=item $current_cb = $w->cb |
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=item $old_cb = $w->cb ($new_cb) |
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1.23 |
Queries the callback on the watcher and optionally changes it. You can do |
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this at any time without the watcher restarting. |
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=item $current_priority = $w->priority |
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=item $old_priority = $w->priority ($new_priority) |
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Queries the priority on the watcher and optionally changes it. Pending |
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watchers with higher priority will be invoked first. The valid range of |
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1.24 |
priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default |
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-2). If the priority is outside this range it will automatically be |
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1.23 |
normalised to the nearest valid priority. |
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1.50 |
The default priority of any newly-created watcher is 0. |
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Note that the priority semantics have not yet been fleshed out and are |
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subject to almost certain change. |
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1.20 |
|
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1.65 |
=item $w->invoke ($revents) |
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1.20 |
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Call the callback *now* with the given event mask. |
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1.65 |
=item $w->feed_event ($revents) |
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Feed some events on this watcher into EV. EV will react to this call as if |
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the watcher had received the given C<$revents> mask. |
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=item $revents = $w->clear_pending |
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If the watcher is pending, this function returns clears its pending status |
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and returns its C<$revents> bitset (as if its callback was invoked). If the |
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watcher isn't pending it does nothing and returns C<0>. |
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1.50 |
=item $previous_state = $w->keepalive ($bool) |
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Normally, C<EV::loop> will return when there are no active watchers |
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(which is a "deadlock" because no progress can be made anymore). This is |
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convinient because it allows you to start your watchers (and your jobs), |
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call C<EV::loop> once and when it returns you know that all your jobs are |
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finished (or they forgot to register some watchers for their task :). |
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Sometimes, however, this gets in your way, for example when you the module |
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that calls C<EV::loop> (usually the main program) is not the same module |
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as a long-living watcher (for example a DNS client module written by |
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somebody else even). Then you might want any outstanding requests to be |
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handled, but you would not want to keep C<EV::loop> from returning just |
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because you happen to have this long-running UDP port watcher. |
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In this case you can clear the keepalive status, which means that even |
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though your watcher is active, it won't keep C<EV::loop> from returning. |
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The initial value for keepalive is true (enabled), and you cna change it |
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any time. |
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1.62 |
Example: Register an I/O watcher for some UDP socket but do not keep the |
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1.50 |
event loop from running just because of that watcher. |
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my $udp_socket = ... |
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my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; |
311 |
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$udp_watcher->keepalive (0); |
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1.20 |
|
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1.54 |
=back |
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=head2 WATCHER TYPES |
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Each of the following subsections describes a single watcher type. |
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1.62 |
=head3 I/O WATCHERS - is this file descriptor readable or writable? |
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1.54 |
|
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=over 4 |
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1.20 |
=item $w = EV::io $fileno_or_fh, $eventmask, $callback |
325 |
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1.2 |
|
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1.20 |
=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
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1.7 |
|
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1.20 |
As long as the returned watcher object is alive, call the C<$callback> |
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1.54 |
when at least one of events specified in C<$eventmask> occurs. |
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1.2 |
|
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1.20 |
The $eventmask can be one or more of these constants ORed together: |
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1.2 |
|
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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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1.7 |
|
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1.20 |
The C<io_ns> variant doesn't start (activate) the newly created watcher. |
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1.2 |
|
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1.20 |
=item $w->set ($fileno_or_fh, $eventmask) |
339 |
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1.10 |
|
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1.20 |
Reconfigures the watcher, see the constructor above for details. Can be |
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called at any time. |
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1.10 |
|
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1.20 |
=item $current_fh = $w->fh |
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=item $old_fh = $w->fh ($new_fh) |
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347 |
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Returns the previously set filehandle and optionally set a new one. |
348 |
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1.10 |
|
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1.20 |
=item $current_eventmask = $w->events |
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=item $old_eventmask = $w->events ($new_eventmask) |
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1.10 |
|
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1.20 |
Returns the previously set event mask and optionally set a new one. |
354 |
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1.10 |
|
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1.54 |
=back |
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|
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=head3 TIMER WATCHERS - relative and optionally repeating timeouts |
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|
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=over 4 |
361 |
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1.10 |
|
362 |
root |
1.20 |
=item $w = EV::timer $after, $repeat, $callback |
363 |
root |
1.2 |
|
364 |
root |
1.20 |
=item $w = EV::timer_ns $after, $repeat, $callback |
365 |
root |
1.2 |
|
366 |
root |
1.53 |
Calls the callback after C<$after> seconds (which may be fractional). If |
367 |
|
|
C<$repeat> is non-zero, the timer will be restarted (with the $repeat |
368 |
|
|
value as $after) after the callback returns. |
369 |
root |
1.2 |
|
370 |
root |
1.20 |
This means that the callback would be called roughly after C<$after> |
371 |
root |
1.39 |
seconds, and then every C<$repeat> seconds. The timer does his best not |
372 |
|
|
to drift, but it will not invoke the timer more often then once per event |
373 |
|
|
loop iteration, and might drift in other cases. If that isn't acceptable, |
374 |
|
|
look at EV::periodic, which can provide long-term stable timers. |
375 |
root |
1.2 |
|
376 |
root |
1.39 |
The timer is based on a monotonic clock, that is, if somebody is sitting |
377 |
root |
1.20 |
in front of the machine while the timer is running and changes the system |
378 |
|
|
clock, the timer will nevertheless run (roughly) the same time. |
379 |
root |
1.2 |
|
380 |
root |
1.20 |
The C<timer_ns> variant doesn't start (activate) the newly created watcher. |
381 |
|
|
|
382 |
|
|
=item $w->set ($after, $repeat) |
383 |
|
|
|
384 |
root |
1.54 |
Reconfigures the watcher, see the constructor above for details. Can be called at |
385 |
root |
1.20 |
any time. |
386 |
|
|
|
387 |
|
|
=item $w->again |
388 |
|
|
|
389 |
|
|
Similar to the C<start> method, but has special semantics for repeating timers: |
390 |
|
|
|
391 |
root |
1.39 |
If the timer is active and non-repeating, it will be stopped. |
392 |
|
|
|
393 |
root |
1.20 |
If the timer is active and repeating, reset the timeout to occur |
394 |
|
|
C<$repeat> seconds after now. |
395 |
|
|
|
396 |
root |
1.39 |
If the timer is inactive and repeating, start it using the repeat value. |
397 |
root |
1.20 |
|
398 |
|
|
Otherwise do nothing. |
399 |
|
|
|
400 |
|
|
This behaviour is useful when you have a timeout for some IO |
401 |
|
|
operation. You create a timer object with the same value for C<$after> and |
402 |
|
|
C<$repeat>, and then, in the read/write watcher, run the C<again> method |
403 |
|
|
on the timeout. |
404 |
|
|
|
405 |
root |
1.54 |
=back |
406 |
|
|
|
407 |
|
|
|
408 |
|
|
=head3 PERIODIC WATCHERS - to cron or not to cron? |
409 |
|
|
|
410 |
|
|
=over 4 |
411 |
root |
1.20 |
|
412 |
root |
1.30 |
=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
413 |
root |
1.20 |
|
414 |
root |
1.30 |
=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
415 |
|
|
|
416 |
|
|
Similar to EV::timer, but is not based on relative timeouts but on |
417 |
|
|
absolute times. Apart from creating "simple" timers that trigger "at" the |
418 |
|
|
specified time, it can also be used for non-drifting absolute timers and |
419 |
|
|
more complex, cron-like, setups that are not adversely affected by time |
420 |
|
|
jumps (i.e. when the system clock is changed by explicit date -s or other |
421 |
|
|
means such as ntpd). It is also the most complex watcher type in EV. |
422 |
|
|
|
423 |
|
|
It has three distinct "modes": |
424 |
|
|
|
425 |
|
|
=over 4 |
426 |
root |
1.2 |
|
427 |
root |
1.30 |
=item * absolute timer ($interval = $reschedule_cb = 0) |
428 |
root |
1.2 |
|
429 |
root |
1.30 |
This time simply fires at the wallclock time C<$at> and doesn't repeat. It |
430 |
|
|
will not adjust when a time jump occurs, that is, if it is to be run |
431 |
|
|
at January 1st 2011 then it will run when the system time reaches or |
432 |
|
|
surpasses this time. |
433 |
root |
1.2 |
|
434 |
root |
1.30 |
=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) |
435 |
root |
1.2 |
|
436 |
root |
1.30 |
In this mode the watcher will always be scheduled to time out at the |
437 |
|
|
next C<$at + N * $interval> time (for some integer N) and then repeat, |
438 |
|
|
regardless of any time jumps. |
439 |
|
|
|
440 |
|
|
This can be used to create timers that do not drift with respect to system |
441 |
|
|
time: |
442 |
|
|
|
443 |
|
|
my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; |
444 |
|
|
|
445 |
|
|
That doesn't mean there will always be 3600 seconds in between triggers, |
446 |
|
|
but only that the the clalback will be called when the system time shows a |
447 |
|
|
full hour (UTC). |
448 |
root |
1.2 |
|
449 |
root |
1.7 |
Another way to think about it (for the mathematically inclined) is that |
450 |
root |
1.30 |
EV::periodic will try to run the callback in this mode at the next |
451 |
|
|
possible time where C<$time = $at (mod $interval)>, regardless of any time |
452 |
|
|
jumps. |
453 |
|
|
|
454 |
|
|
=item * manual reschedule mode ($reschedule_cb = coderef) |
455 |
|
|
|
456 |
root |
1.37 |
In this mode $interval and $at are both being ignored. Instead, each |
457 |
|
|
time the periodic watcher gets scheduled, the reschedule callback |
458 |
|
|
($reschedule_cb) will be called with the watcher as first, and the current |
459 |
|
|
time as second argument. |
460 |
root |
1.30 |
|
461 |
root |
1.31 |
I<This callback MUST NOT stop or destroy this or any other periodic |
462 |
|
|
watcher, ever>. If you need to stop it, return 1e30 and stop it |
463 |
|
|
afterwards. |
464 |
root |
1.30 |
|
465 |
|
|
It must return the next time to trigger, based on the passed time value |
466 |
|
|
(that is, the lowest time value larger than to the second argument). It |
467 |
|
|
will usually be called just before the callback will be triggered, but |
468 |
|
|
might be called at other times, too. |
469 |
|
|
|
470 |
|
|
This can be used to create very complex timers, such as a timer that |
471 |
|
|
triggers on each midnight, local time (actually 24 hours after the last |
472 |
|
|
midnight, to keep the example simple. If you know a way to do it correctly |
473 |
|
|
in about the same space (without requiring elaborate modules), drop me a |
474 |
|
|
note :): |
475 |
|
|
|
476 |
|
|
my $daily = EV::periodic 0, 0, sub { |
477 |
|
|
my ($w, $now) = @_; |
478 |
|
|
|
479 |
|
|
use Time::Local (); |
480 |
|
|
my (undef, undef, undef, $d, $m, $y) = localtime $now; |
481 |
|
|
86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y |
482 |
|
|
}, sub { |
483 |
|
|
print "it's midnight or likely shortly after, now\n"; |
484 |
|
|
}; |
485 |
root |
1.7 |
|
486 |
root |
1.30 |
=back |
487 |
root |
1.20 |
|
488 |
|
|
The C<periodic_ns> variant doesn't start (activate) the newly created watcher. |
489 |
root |
1.2 |
|
490 |
root |
1.30 |
=item $w->set ($at, $interval, $reschedule_cb) |
491 |
root |
1.11 |
|
492 |
root |
1.54 |
Reconfigures the watcher, see the constructor above for details. Can be called at |
493 |
root |
1.20 |
any time. |
494 |
|
|
|
495 |
root |
1.30 |
=item $w->again |
496 |
|
|
|
497 |
|
|
Simply stops and starts the watcher again. |
498 |
|
|
|
499 |
root |
1.54 |
=back |
500 |
|
|
|
501 |
|
|
|
502 |
|
|
=head3 SIGNAL WATCHERS - signal me when a signal gets signalled! |
503 |
|
|
|
504 |
|
|
=over 4 |
505 |
root |
1.20 |
|
506 |
|
|
=item $w = EV::signal $signal, $callback |
507 |
|
|
|
508 |
|
|
=item $w = EV::signal_ns $signal, $callback |
509 |
root |
1.11 |
|
510 |
root |
1.54 |
Call the callback when $signal is received (the signal can be specified by |
511 |
|
|
number or by name, just as with C<kill> or C<%SIG>). |
512 |
root |
1.2 |
|
513 |
root |
1.11 |
EV will grab the signal for the process (the kernel only allows one |
514 |
root |
1.20 |
component to receive a signal at a time) when you start a signal watcher, |
515 |
|
|
and removes it again when you stop it. Perl does the same when you |
516 |
root |
1.54 |
add/remove callbacks to C<%SIG>, so watch out. |
517 |
root |
1.20 |
|
518 |
|
|
You can have as many signal watchers per signal as you want. |
519 |
root |
1.2 |
|
520 |
root |
1.20 |
The C<signal_ns> variant doesn't start (activate) the newly created watcher. |
521 |
root |
1.2 |
|
522 |
root |
1.20 |
=item $w->set ($signal) |
523 |
root |
1.2 |
|
524 |
root |
1.54 |
Reconfigures the watcher, see the constructor above for details. Can be |
525 |
|
|
called at any time. |
526 |
root |
1.20 |
|
527 |
root |
1.22 |
=item $current_signum = $w->signal |
528 |
|
|
|
529 |
|
|
=item $old_signum = $w->signal ($new_signal) |
530 |
|
|
|
531 |
|
|
Returns the previously set signal (always as a number not name) and |
532 |
|
|
optionally set a new one. |
533 |
|
|
|
534 |
root |
1.54 |
=back |
535 |
|
|
|
536 |
|
|
|
537 |
|
|
=head3 CHILD WATCHERS - watch out for process status changes |
538 |
|
|
|
539 |
|
|
=over 4 |
540 |
root |
1.20 |
|
541 |
|
|
=item $w = EV::child $pid, $callback |
542 |
|
|
|
543 |
|
|
=item $w = EV::child_ns $pid, $callback |
544 |
|
|
|
545 |
root |
1.54 |
Call the callback when a status change for pid C<$pid> (or any pid if |
546 |
|
|
C<$pid> is 0) has been received. More precisely: when the process receives |
547 |
|
|
a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all |
548 |
root |
1.20 |
changed/zombie children and call the callback. |
549 |
|
|
|
550 |
root |
1.54 |
It is valid (and fully supported) to install a child watcher after a child |
551 |
|
|
has exited but before the event loop has started its next iteration (for |
552 |
|
|
example, first you C<fork>, then the new child process might exit, and |
553 |
|
|
only then do you install a child watcher in the parent for the new pid). |
554 |
|
|
|
555 |
|
|
You can access both exit (or tracing) status and pid by using the |
556 |
|
|
C<rstatus> and C<rpid> methods on the watcher object. |
557 |
root |
1.20 |
|
558 |
root |
1.54 |
You can have as many pid watchers per pid as you want, they will all be |
559 |
|
|
called. |
560 |
root |
1.20 |
|
561 |
|
|
The C<child_ns> variant doesn't start (activate) the newly created watcher. |
562 |
|
|
|
563 |
|
|
=item $w->set ($pid) |
564 |
root |
1.1 |
|
565 |
root |
1.54 |
Reconfigures the watcher, see the constructor above for details. Can be called at |
566 |
root |
1.20 |
any time. |
567 |
root |
1.2 |
|
568 |
root |
1.22 |
=item $current_pid = $w->pid |
569 |
|
|
|
570 |
|
|
=item $old_pid = $w->pid ($new_pid) |
571 |
|
|
|
572 |
|
|
Returns the previously set process id and optionally set a new one. |
573 |
|
|
|
574 |
root |
1.27 |
=item $exit_status = $w->rstatus |
575 |
|
|
|
576 |
|
|
Return the exit/wait status (as returned by waitpid, see the waitpid entry |
577 |
|
|
in perlfunc). |
578 |
|
|
|
579 |
|
|
=item $pid = $w->rpid |
580 |
|
|
|
581 |
|
|
Return the pid of the awaited child (useful when you have installed a |
582 |
|
|
watcher for all pids). |
583 |
|
|
|
584 |
root |
1.54 |
=back |
585 |
|
|
|
586 |
|
|
|
587 |
root |
1.56 |
=head3 STAT WATCHERS - did the file attributes just change? |
588 |
|
|
|
589 |
|
|
=over 4 |
590 |
|
|
|
591 |
|
|
=item $w = EV::stat $path, $interval, $callback |
592 |
|
|
|
593 |
|
|
=item $w = EV::stat_ns $path, $interval, $callback |
594 |
|
|
|
595 |
|
|
Call the callback when a file status change has been detected on |
596 |
|
|
C<$path>. The C<$path> does not need to exist, changing from "path exists" |
597 |
|
|
to "path does not exist" is a status change like any other. |
598 |
|
|
|
599 |
|
|
The C<$interval> is a recommended polling interval for systems where |
600 |
|
|
OS-supported change notifications don't exist or are not supported. If |
601 |
|
|
you use C<0> then an unspecified default is used (which is highly |
602 |
|
|
recommended!), which is to be expected to be around five seconds usually. |
603 |
|
|
|
604 |
|
|
This watcher type is not meant for massive numbers of stat watchers, |
605 |
|
|
as even with OS-supported change notifications, this can be |
606 |
|
|
resource-intensive. |
607 |
|
|
|
608 |
|
|
The C<stat_ns> variant doesn't start (activate) the newly created watcher. |
609 |
|
|
|
610 |
root |
1.57 |
=item ... = $w->stat |
611 |
|
|
|
612 |
|
|
This call is very similar to the perl C<stat> built-in: It stats (using |
613 |
|
|
C<lstat>) the path specified in the watcher and sets perls stat cache (as |
614 |
|
|
well as EV's idea of the current stat values) to the values found. |
615 |
|
|
|
616 |
|
|
In scalar context, a boolean is return indicating success or failure of |
617 |
|
|
the stat. In list context, the same 13-value list as with stat is returned |
618 |
|
|
(except that the blksize and blocks fields are not reliable). |
619 |
|
|
|
620 |
|
|
In the case of an error, errno is set to C<ENOENT> (regardless of the |
621 |
|
|
actual error value) and the C<nlink> value is forced to zero (if the stat |
622 |
|
|
was successful then nlink is guaranteed to be non-zero). |
623 |
|
|
|
624 |
|
|
See also the next two entries for more info. |
625 |
|
|
|
626 |
|
|
=item ... = $w->attr |
627 |
|
|
|
628 |
|
|
Just like C<< $w->stat >>, but without the initial stat'ing: this returns |
629 |
|
|
the values most recently detected by EV. See the next entry for more info. |
630 |
|
|
|
631 |
|
|
=item ... = $w->prev |
632 |
|
|
|
633 |
|
|
Just like C<< $w->stat >>, but without the initial stat'ing: this returns |
634 |
|
|
the previous set of values, before the change. |
635 |
|
|
|
636 |
|
|
That is, when the watcher callback is invoked, C<< $w->prev >> will be set |
637 |
|
|
to the values found I<before> a change was detected, while C<< $w->attr >> |
638 |
|
|
returns the values found leading to the change detection. The difference (if any) |
639 |
|
|
between C<prev> and C<attr> is what triggered the callback. |
640 |
|
|
|
641 |
|
|
If you did something to the filesystem object and do not want to trigger |
642 |
|
|
yet another change, you can call C<stat> to update EV's idea of what the |
643 |
|
|
current attributes are. |
644 |
|
|
|
645 |
root |
1.56 |
=item $w->set ($path, $interval) |
646 |
|
|
|
647 |
|
|
Reconfigures the watcher, see the constructor above for details. Can be |
648 |
|
|
called at any time. |
649 |
|
|
|
650 |
|
|
=item $current_path = $w->path |
651 |
|
|
|
652 |
|
|
=item $old_path = $w->path ($new_path) |
653 |
|
|
|
654 |
|
|
Returns the previously set path and optionally set a new one. |
655 |
|
|
|
656 |
|
|
=item $current_interval = $w->interval |
657 |
|
|
|
658 |
|
|
=item $old_interval = $w->interval ($new_interval) |
659 |
|
|
|
660 |
|
|
Returns the previously set interval and optionally set a new one. Can be |
661 |
|
|
used to query the actual interval used. |
662 |
|
|
|
663 |
|
|
=back |
664 |
|
|
|
665 |
|
|
|
666 |
root |
1.54 |
=head3 IDLE WATCHERS - when you've got nothing better to do... |
667 |
|
|
|
668 |
|
|
=over 4 |
669 |
root |
1.2 |
|
670 |
root |
1.20 |
=item $w = EV::idle $callback |
671 |
root |
1.2 |
|
672 |
root |
1.20 |
=item $w = EV::idle_ns $callback |
673 |
root |
1.2 |
|
674 |
root |
1.62 |
Call the callback when there are no other pending watchers of the same or |
675 |
|
|
higher priority (excluding check, prepare and other idle watchers of the |
676 |
|
|
same or lower priority, of course). They are called idle watchers because |
677 |
|
|
when the watcher is the highest priority pending event in the process, the |
678 |
|
|
process is considered to be idle at that priority. |
679 |
|
|
|
680 |
|
|
If you want a watcher that is only ever called when I<no> other events are |
681 |
|
|
outstanding you have to set the priority to C<EV::MINPRI>. |
682 |
root |
1.2 |
|
683 |
root |
1.20 |
The process will not block as long as any idle watchers are active, and |
684 |
|
|
they will be called repeatedly until stopped. |
685 |
root |
1.2 |
|
686 |
root |
1.62 |
For example, if you have idle watchers at priority C<0> and C<1>, and |
687 |
|
|
an I/O watcher at priority C<0>, then the idle watcher at priority C<1> |
688 |
|
|
and the I/O watcher will always run when ready. Only when the idle watcher |
689 |
|
|
at priority C<1> is stopped and the I/O watcher at priority C<0> is not |
690 |
|
|
pending with the C<0>-priority idle watcher be invoked. |
691 |
|
|
|
692 |
root |
1.20 |
The C<idle_ns> variant doesn't start (activate) the newly created watcher. |
693 |
root |
1.2 |
|
694 |
root |
1.54 |
=back |
695 |
|
|
|
696 |
|
|
|
697 |
|
|
=head3 PREPARE WATCHERS - customise your event loop! |
698 |
|
|
|
699 |
|
|
=over 4 |
700 |
root |
1.2 |
|
701 |
root |
1.20 |
=item $w = EV::prepare $callback |
702 |
root |
1.1 |
|
703 |
root |
1.20 |
=item $w = EV::prepare_ns $callback |
704 |
root |
1.1 |
|
705 |
root |
1.20 |
Call the callback just before the process would block. You can still |
706 |
|
|
create/modify any watchers at this point. |
707 |
root |
1.1 |
|
708 |
root |
1.20 |
See the EV::check watcher, below, for explanations and an example. |
709 |
root |
1.2 |
|
710 |
root |
1.20 |
The C<prepare_ns> variant doesn't start (activate) the newly created watcher. |
711 |
root |
1.2 |
|
712 |
root |
1.54 |
=back |
713 |
|
|
|
714 |
|
|
|
715 |
|
|
=head3 CHECK WATCHERS - customise your event loop even more! |
716 |
|
|
|
717 |
|
|
=over 4 |
718 |
root |
1.2 |
|
719 |
root |
1.20 |
=item $w = EV::check $callback |
720 |
root |
1.2 |
|
721 |
root |
1.20 |
=item $w = EV::check_ns $callback |
722 |
root |
1.10 |
|
723 |
root |
1.20 |
Call the callback just after the process wakes up again (after it has |
724 |
|
|
gathered events), but before any other callbacks have been invoked. |
725 |
root |
1.10 |
|
726 |
root |
1.20 |
This is used to integrate other event-based software into the EV |
727 |
|
|
mainloop: You register a prepare callback and in there, you create io and |
728 |
|
|
timer watchers as required by the other software. Here is a real-world |
729 |
|
|
example of integrating Net::SNMP (with some details left out): |
730 |
root |
1.10 |
|
731 |
root |
1.20 |
our @snmp_watcher; |
732 |
root |
1.2 |
|
733 |
root |
1.20 |
our $snmp_prepare = EV::prepare sub { |
734 |
|
|
# do nothing unless active |
735 |
|
|
$dispatcher->{_event_queue_h} |
736 |
|
|
or return; |
737 |
root |
1.2 |
|
738 |
root |
1.20 |
# make the dispatcher handle any outstanding stuff |
739 |
root |
1.45 |
... not shown |
740 |
root |
1.2 |
|
741 |
root |
1.62 |
# create an I/O watcher for each and every socket |
742 |
root |
1.20 |
@snmp_watcher = ( |
743 |
|
|
(map { EV::io $_, EV::READ, sub { } } |
744 |
|
|
keys %{ $dispatcher->{_descriptors} }), |
745 |
root |
1.45 |
|
746 |
|
|
EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] |
747 |
|
|
? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0), |
748 |
|
|
0, sub { }, |
749 |
root |
1.20 |
); |
750 |
|
|
}; |
751 |
root |
1.2 |
|
752 |
root |
1.45 |
The callbacks are irrelevant (and are not even being called), the |
753 |
|
|
only purpose of those watchers is to wake up the process as soon as |
754 |
|
|
one of those events occurs (socket readable, or timer timed out). The |
755 |
|
|
corresponding EV::check watcher will then clean up: |
756 |
root |
1.2 |
|
757 |
root |
1.20 |
our $snmp_check = EV::check sub { |
758 |
|
|
# destroy all watchers |
759 |
|
|
@snmp_watcher = (); |
760 |
root |
1.2 |
|
761 |
root |
1.20 |
# make the dispatcher handle any new stuff |
762 |
root |
1.45 |
... not shown |
763 |
root |
1.20 |
}; |
764 |
root |
1.2 |
|
765 |
root |
1.20 |
The callbacks of the created watchers will not be called as the watchers |
766 |
|
|
are destroyed before this cna happen (remember EV::check gets called |
767 |
|
|
first). |
768 |
root |
1.2 |
|
769 |
root |
1.20 |
The C<check_ns> variant doesn't start (activate) the newly created watcher. |
770 |
root |
1.1 |
|
771 |
|
|
=back |
772 |
|
|
|
773 |
root |
1.54 |
|
774 |
root |
1.56 |
=head3 FORK WATCHERS - the audacity to resume the event loop after a fork |
775 |
root |
1.54 |
|
776 |
root |
1.56 |
Fork watchers are called when a C<fork ()> was detected. The invocation |
777 |
|
|
is done before the event loop blocks next and before C<check> watchers |
778 |
|
|
are being called, and only in the child after the fork. |
779 |
root |
1.54 |
|
780 |
root |
1.56 |
=over 4 |
781 |
root |
1.54 |
|
782 |
root |
1.56 |
=item $w = EV::fork $callback |
783 |
root |
1.54 |
|
784 |
root |
1.56 |
=item $w = EV::fork_ns $callback |
785 |
root |
1.54 |
|
786 |
root |
1.56 |
Call the callback before the event loop is resumed in the child process |
787 |
|
|
after a fork. |
788 |
root |
1.54 |
|
789 |
root |
1.56 |
The C<fork_ns> variant doesn't start (activate) the newly created watcher. |
790 |
root |
1.54 |
|
791 |
|
|
=back |
792 |
|
|
|
793 |
|
|
|
794 |
root |
1.61 |
=head1 PERL SIGNALS |
795 |
|
|
|
796 |
|
|
While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour |
797 |
|
|
with EV is as the same as any other C library: Perl-signals will only be |
798 |
|
|
handled when Perl runs, which means your signal handler might be invoked |
799 |
|
|
only the next time an event callback is invoked. |
800 |
|
|
|
801 |
|
|
The solution is to use EV signal watchers (see C<EV::signal>), which will |
802 |
|
|
ensure proper operations with regards to other event watchers. |
803 |
|
|
|
804 |
|
|
If you cannot do this for whatever reason, you can also force a watcher |
805 |
|
|
to be called on every event loop iteration by installing a C<EV::check> |
806 |
|
|
watcher: |
807 |
|
|
|
808 |
|
|
my $async_check = EV::check sub { }; |
809 |
|
|
|
810 |
|
|
This ensures that perl shortly gets into control for a short time, and |
811 |
|
|
also ensures slower overall operation. |
812 |
|
|
|
813 |
root |
1.13 |
=head1 THREADS |
814 |
|
|
|
815 |
root |
1.45 |
Threads are not supported by this module in any way. Perl pseudo-threads |
816 |
root |
1.46 |
is evil stuff and must die. As soon as Perl gains real threads I will work |
817 |
|
|
on thread support for it. |
818 |
|
|
|
819 |
|
|
=head1 FORK |
820 |
|
|
|
821 |
|
|
Most of the "improved" event delivering mechanisms of modern operating |
822 |
|
|
systems have quite a few problems with fork(2) (to put it bluntly: it is |
823 |
|
|
not supported and usually destructive). Libev makes it possible to work |
824 |
|
|
around this by having a function that recreates the kernel state after |
825 |
|
|
fork in the child. |
826 |
|
|
|
827 |
|
|
On non-win32 platforms, this module requires the pthread_atfork |
828 |
|
|
functionality to do this automatically for you. This function is quite |
829 |
|
|
buggy on most BSDs, though, so YMMV. The overhead for this is quite |
830 |
|
|
negligible, because everything the function currently does is set a flag |
831 |
|
|
that is checked only when the event loop gets used the next time, so when |
832 |
|
|
you do fork but not use EV, the overhead is minimal. |
833 |
|
|
|
834 |
|
|
On win32, there is no notion of fork so all this doesn't apply, of course. |
835 |
root |
1.13 |
|
836 |
root |
1.1 |
=cut |
837 |
|
|
|
838 |
root |
1.8 |
our $DIED = sub { |
839 |
|
|
warn "EV: error in callback (ignoring): $@"; |
840 |
|
|
}; |
841 |
|
|
|
842 |
root |
1.28 |
default_loop |
843 |
root |
1.68 |
or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?'; |
844 |
root |
1.1 |
|
845 |
|
|
1; |
846 |
|
|
|
847 |
root |
1.3 |
=head1 SEE ALSO |
848 |
|
|
|
849 |
root |
1.59 |
L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as |
850 |
|
|
event loop), L<Coro::EV> (efficient coroutines with EV). |
851 |
root |
1.3 |
|
852 |
root |
1.1 |
=head1 AUTHOR |
853 |
|
|
|
854 |
|
|
Marc Lehmann <schmorp@schmorp.de> |
855 |
|
|
http://home.schmorp.de/ |
856 |
|
|
|
857 |
|
|
=cut |
858 |
|
|
|