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NAME |
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EV - perl interface to libevent, monkey.org/~provos/libevent/ |
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|
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SYNOPSIS |
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use EV; |
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|
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# TIMER |
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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::timer_abs 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 $w = EV::io \*STDIN, EV::READ | EV::PERSIST, sub { |
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my ($w, $events) = @_; # all callbacks get the watcher object and event mask |
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if ($events & EV::TIMEOUT) { |
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warn "nothing received on stdin for 10 seconds, retrying"; |
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} else { |
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warn "stdin is readable, you entered: ", <STDIN>; |
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} |
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}; |
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$w->timeout (10); |
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|
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my $w = EV::timed_io \*STDIN, EV::READ, 30, sub { |
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my ($w, $events) = @_; |
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if ($_[1] & EV::TIMEOUT) { |
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warn "nothing entered within 30 seconds, bye bye.\n"; |
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$w->stop; |
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} else { |
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my $line = <STDIN>; |
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warn "you entered something, you again have 30 seconds.\n"; |
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} |
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}; |
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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 $w = EV::signal 3, sub { |
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warn "sigquit received (this is GNU/Linux, right?)\n"; |
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}; |
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|
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# MAINLOOP |
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EV::dispatch; # loop as long as watchers are active |
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EV::loop; # the same thing |
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EV::loop EV::LOOP_ONCE; # block until some events could be handles |
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EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait |
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|
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DESCRIPTION |
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This module provides an interface to libevent |
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(<http://monkey.org/~provos/libevent/>). You probably should acquaint |
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yourself with its documentation and source code to be able to use this |
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module fully. |
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|
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Please note thta this module disables the libevent EPOLL method by |
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default, see BUGS, below, if you need to enable it. |
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|
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BASIC INTERFACE |
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$EV::NPRI |
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How many priority levels are available. |
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|
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$EV::DIED |
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Must contain a reference to a function that is called when a |
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callback throws an exception (with $@ containing thr error). The |
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default prints an informative message and continues. |
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|
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If this callback throws an exception it will be silently ignored. |
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|
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$time = EV::now |
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Returns the time in (fractional) seconds since the epoch. |
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|
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$version = EV::version |
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$method = EV::method |
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Return version string and event polling method used. |
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|
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EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT |
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EV::loopexit $after |
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Exit any active loop or dispatch after $after seconds or immediately |
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if $after is missing or zero. |
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|
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EV::dispatch |
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Same as "EV::loop 0". |
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|
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EV::event $callback |
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Creates a new event watcher waiting for nothing, calling the given |
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callback. |
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|
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my $w = EV::io $fileno_or_fh, $eventmask, $callback |
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my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
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As long as the returned watcher object is alive, call the $callback |
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when the events specified in $eventmask happen. Initially, the |
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timeout is disabled. |
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|
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You can additionall set a timeout to occur on the watcher, but note |
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that this timeout will not be reset when you get an I/O event in the |
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EV::PERSIST case, and reaching a timeout will always stop the |
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watcher even in the EV::PERSIST case. |
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|
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If you want a timeout to occur only after a specific time of |
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inactivity, set a repeating timeout and do NOT use EV::PERSIST. |
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|
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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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EV::PERSIST stay active after a (non-timeout) event occured |
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|
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The "io_ns" variant doesn't add/start the newly created watcher. |
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|
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my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback |
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my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback |
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Same as "io" and "io_ns", but also specifies a timeout (as if there |
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was a call to "$w->timeout ($timout, 1)". The persist flag is not |
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allowed and will automatically be cleared. The watcher will be |
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restarted after each event. |
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|
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If the timeout is zero or undef, no timeout will be set, and a |
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normal watcher (with the persist flag set!) will be created. |
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|
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This has the effect of timing out after the specified period of |
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inactivity has happened. |
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|
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Due to the design of libevent, this is also relatively inefficient, |
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having one or two io watchers and a separate timeout watcher that |
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you reset on activity (by calling its "start" method) is usually |
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more efficient. |
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|
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my $w = EV::timer $after, $repeat, $callback |
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my $w = EV::timer_ns $after, $repeat, $callback |
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Calls the callback after $after seconds. If $repeat is true, the |
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timer will be restarted after the callback returns. This means that |
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the callback would be called roughly every $after seconds, prolonged |
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by the time the callback takes. |
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|
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The "timer_ns" variant doesn't add/start the newly created watcher. |
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|
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my $w = EV::timer_abs $at, $interval, $callback |
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my $w = EV::timer_abs_ns $at, $interval, $callback |
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Similar to EV::timer, but the time is given as an absolute point in |
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time ($at), plus an optional $interval. |
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|
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If the $interval is zero, then the callback will be called at the |
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time $at if that is in the future, or as soon as possible if its in |
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the past. It will not automatically repeat. |
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|
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If the $interval is nonzero, then the watcher will always be |
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scheduled to time out at the next "$at + integer * $interval" time. |
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|
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This can be used to schedule a callback to run at very regular |
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intervals, as long as the processing time is less then the interval |
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(otherwise obviously events will be skipped). |
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|
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Another way to think about it (for the mathematically inclined) is |
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that "timer_abs" will try to tun the callback at the next possible |
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time where "$time = $at (mod $interval)", regardless of any time |
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jumps. |
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|
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The "timer_abs_ns" variant doesn't add/start the newly created |
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watcher. |
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|
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my $w = EV::signal $signal, $callback |
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my $w = EV::signal_ns $signal, $callback |
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Call the callback when $signal is received (the signal can be |
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specified by number or by name, just as with kill or %SIG). Signal |
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watchers are persistent no natter what. |
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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 signals) when you start a signal watcher, and |
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removes it again when you stop it. Pelr 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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Unfortunately, only one handler can be registered per signal. Screw |
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libevent. |
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|
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The "signal_ns" variant doesn't add/start the newly created watcher. |
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|
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THE EV::Event CLASS |
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All EV functions creating an event watcher (designated by "my $w =" |
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above) support the following methods on the returned watcher object: |
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|
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$w->add ($timeout) |
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Stops and (re-)starts the event watcher, setting the optional |
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timeout to the given value, or clearing the timeout if none is |
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given. |
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|
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$w->start |
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Stops and (re-)starts the event watcher without touching the |
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timeout. |
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|
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$w->del |
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$w->stop |
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Stop the event watcher if it was started. |
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|
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$current_callback = $w->cb |
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$old_callback = $w->cb ($new_callback) |
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Return the previously set callback and optionally set a new one. |
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|
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$current_fh = $w->fh |
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$old_fh = $w->fh ($new_fh) |
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Returns the previously set filehandle and optionally set a new one |
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(also clears the EV::SIGNAL flag when setting a filehandle). |
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|
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$current_signal = $w->signal |
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$old_signal = $w->signal ($new_signal) |
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Returns the previously set signal number and optionally set a new |
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one (also sets the EV::SIGNAL flag when setting a signal). |
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|
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$current_eventmask = $w->events |
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$old_eventmask = $w->events ($new_eventmask) |
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Returns the previously set event mask and optionally set a new one. |
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|
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$w->timeout ($after, $repeat) |
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Resets the timeout (see "EV::timer" for details). |
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|
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$w->timeout_abs ($at, $interval) |
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Resets the timeout (see "EV::timer_abs" for details). |
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|
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$w->priority_set ($priority) |
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Set the priority of the watcher to $priority (0 <= $priority < |
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$EV::NPRI). |
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|
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BUGS |
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Lots. Libevent itself isn't well tested and rather buggy, and this |
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module is quite new at the moment. |
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|
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Please note that the epoll method is not, in general, reliable in |
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programs that use fork (even if no libveent calls are being made in the |
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forked process). If your program behaves erratically, try setting the |
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environment variable "EVENT_NOEPOLL" first when running the program. |
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|
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In general, if you fork, then you can only use the EV module in one of |
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the children. |
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|
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SEE ALSO |
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L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>. |
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L<EV::AnyEvent>. |
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|
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AUTHOR |
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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|
