--- EV/EV.pm 2007/11/01 11:43:10 1.19 +++ EV/EV.pm 2007/11/01 17:17:32 1.20 @@ -1,12 +1,12 @@ =head1 NAME -EV - perl interface to libevent, monkey.org/~provos/libevent/ +EV - perl interface to libev, a high performance full-featured event loop =head1 SYNOPSIS use EV; - # TIMER + # TIMERS my $w = EV::timer 2, 0, sub { warn "is called after 2s"; @@ -18,31 +18,15 @@ undef $w; # destroy event watcher again - my $w = EV::timer_abs 0, 60, sub { + my $w = EV::periodic 0, 60, sub { warn "is called every minute, on the minute, exactly"; }; # IO - my $w = EV::io \*STDIN, EV::READ | EV::PERSIST, sub { + my $w = EV::io *STDIN, EV::READ, sub { my ($w, $revents) = @_; # all callbacks get the watcher object and event mask - if ($revents & EV::TIMEOUT) { - warn "nothing received on stdin for 10 seconds, retrying"; - } else { - warn "stdin is readable, you entered: ", ; - } - }; - $w->timeout (10); - - my $w = EV::timed_io \*STDIN, EV::READ, 30, sub { - my ($w, $revents) = @_; - if ($revents & EV::TIMEOUT) { - warn "nothing entered within 30 seconds, bye bye.\n"; - $w->stop; - } else { - my $line = ; - warn "you entered something, you again have 30 seconds.\n"; - } + warn "stdin is readable, you entered: ", ; }; # SIGNALS @@ -62,17 +46,14 @@ }; # MAINLOOP - EV::dispatch; # loop as long as watchers are active - EV::loop; # the same thing - EV::loop EV::LOOP_ONESHOT; # block until some events could be handles - EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait + EV::loop; # loop until EV::loop_done is called + EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled + EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block =head1 DESCRIPTION This module provides an interface to libev -(L). You probably should -acquaint yourself with its documentation and source code to be able to use -this module fully. +(L). =cut @@ -99,10 +80,6 @@ =over 4 -=item $EV::NPRI - -How many priority levels are available. - =item $EV::DIED Must contain a reference to a function that is called when a callback @@ -111,194 +88,347 @@ If this callback throws an exception it will be silently ignored. +=item $time = EV::time + +Returns the current time in (fractional) seconds since the epoch. + =item $time = EV::now -Returns the time in (fractional) seconds since the epoch. +Returns the time the last event loop iteration has been started. This +is the time that (relative) timers are based on, and refering to it is +usually faster then calling EV::time. -=item $version = EV::version +=item $method = EV::ev_method -=item $method = EV::method +Returns an integer describing the backend used by libev (EV::METHOD_SELECT +or EV::METHOD_EPOLL). -Return version string and event polling method used. +=item EV::loop [$flags] -=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT +Begin checking for events and calling callbacks. It returns when a +callback calls EV::loop_done. -=item EV::loopexit $after +The $flags argument can be one of the following: -Exit any active loop or dispatch after C<$after> seconds or immediately if -C<$after> is missing or zero. + 0 as above + EV::LOOP_ONESHOT block at most once (wait, but do not loop) + EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) -=item EV::dispatch +=item EV::loop_done [$how] -Same as C. +When called with no arguments or an argument of 1, makes the innermost +call to EV::loop return. -=item EV::event $callback +When called with an agrument of 2, all calls to EV::loop will return as +fast as possible. -Creates a new event watcher waiting for nothing, calling the given callback. +=back -=item my $w = EV::io $fileno_or_fh, $eventmask, $callback +=head2 WATCHER -=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback +A watcher is an object that gets created to record your interest in some +event. For instance, if you want to wait for STDIN to become readable, you +would create an EV::io watcher for that: + + my $watcher = EV::io *STDIN, EV::READ, sub { + my ($watcher, $revents) = @_; + warn "yeah, STDIN should not be readable without blocking!\n" + }; -As long as the returned watcher object is alive, call the C<$callback> -when the events specified in C<$eventmask> happen. Initially, the timeout -is disabled. +All watchers can be active (waiting for events) or inactive (paused). Only +active watchers will have their callbacks invoked. All callbacks will be +called with at least two arguments: the watcher and a bitmask of received +events. + +Each watcher type has its associated bit in revents, so you can use the +same callback for multiple watchers. The event mask is named after the +type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, +EV::periodic sets EV::PERIODIC and so on, with the exception of IO events +(which can set both EV::READ and EV::WRITE bits), and EV::timer (which +uses EV::TIMEOUT). + +In the rare case where one wants to create a watcher but not start it at +the same time, each constructor has a variant with a trailing C<_ns> in +its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. + +Please note that a watcher will automatically be stopped when the watcher +object is returned, so you I to keep the watcher objects returned by +the constructors. + +=head2 WATCHER TYPES + +Now lets move to the existing watcher types and asociated methods. + +The following methods are available for all watchers. Then followes a +description of each watcher constructor (EV::io, EV::timer, EV::periodic, +EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by +any type-specific methods (if any). + +=over 4 + +=item $w->start + +Starts a watcher if it isn't active already. Does nothing to an already +active watcher. By default, all watchers start out in the active state +(see the description of the C<_ns> variants if you need stopped watchers). + +=item $w->stop + +Stop a watcher if it is active. Also clear any pending events (events that +have been received but that didn't yet result in a callback invocation), +regardless of wether the watcher was active or not. + +=item $bool = $w->is_active -You can additionall set a timeout to occur on the watcher, but note that -this timeout will not be reset when you get an I/O event in the EV::PERSIST -case, and reaching a timeout will always stop the watcher even in the -EV::PERSIST case. +Returns true if the watcher is active, false otherwise. -If you want a timeout to occur only after a specific time of inactivity, set -a repeating timeout and do NOT use EV::PERSIST. +=item $current_cb = $w->cb -Eventmask can be one or more of these constants ORed together: +=item $old_cb = $w->cb ($new_cb) + +Queries the callback on the watcher and optionally changes it. You cna do +this at any time. + +=item $w->trigger ($revents) + +Call the callback *now* with the given event mask. + + +=item $w = EV::io $fileno_or_fh, $eventmask, $callback + +=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback + +As long as the returned watcher object is alive, call the C<$callback> +when the events specified in C<$eventmask>. + +The $eventmask can be one or more of these constants ORed together: EV::READ wait until read() wouldn't block anymore EV::WRITE wait until write() wouldn't block anymore - EV::PERSIST stay active after a (non-timeout) event occured -The C variant doesn't add/start the newly created watcher. +The C variant doesn't start (activate) the newly created watcher. -=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback +=item $w->set ($fileno_or_fh, $eventmask) -=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback +Reconfigures the watcher, see the constructor above for details. Can be +called at any time. -Same as C and C, but also specifies a timeout (as if there was -a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed -and will automatically be cleared. The watcher will be restarted after each event. +=item $current_fh = $w->fh + +=item $old_fh = $w->fh ($new_fh) + +Returns the previously set filehandle and optionally set a new one. -If the timeout is zero or undef, no timeout will be set, and a normal -watcher (with the persist flag set!) will be created. +=item $current_eventmask = $w->events + +=item $old_eventmask = $w->events ($new_eventmask) -This has the effect of timing out after the specified period of inactivity -has happened. +Returns the previously set event mask and optionally set a new one. -Due to the design of libevent, this is also relatively inefficient, having -one or two io watchers and a separate timeout watcher that you reset on -activity (by calling its C method) is usually more efficient. -=item my $w = EV::timer $after, $repeat, $callback +=item $w = EV::timer $after, $repeat, $callback -=item my $w = EV::timer_ns $after, $repeat, $callback +=item $w = EV::timer_ns $after, $repeat, $callback -Calls the callback after C<$after> seconds. If C<$repeat> is true, the -timer will be restarted after the callback returns. This means that the -callback would be called roughly every C<$after> seconds, prolonged by the -time the callback takes. +Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, +the timer will be restarted (with the $repeat value as $after) after the +callback returns. -The C variant doesn't add/start the newly created watcher. +This means that the callback would be called roughly after C<$after> +seconds, and then every C<$repeat> seconds. "Roughly" because the time of +callback processing is not taken into account, so the timer will slowly +drift. If that isn't acceptable, look at EV::periodic. -=item my $w = EV::timer_abs $at, $interval, $callback +The timer is based on a monotonic clock, that is if somebody is sitting +in front of the machine while the timer is running and changes the system +clock, the timer will nevertheless run (roughly) the same time. -=item my $w = EV::timer_abs_ns $at, $interval, $callback +The C variant doesn't start (activate) the newly created watcher. + +=item $w->set ($after, $repeat) + +Reconfigures the watcher, see the constructor above for details. Can be at +any time. + +=item $w->again + +Similar to the C method, but has special semantics for repeating timers: + +If the timer is active and repeating, reset the timeout to occur +C<$repeat> seconds after now. + +If the timer is active and non-repeating, it will be stopped. + +If the timer is in active and repeating, start it. + +Otherwise do nothing. + +This behaviour is useful when you have a timeout for some IO +operation. You create a timer object with the same value for C<$after> and +C<$repeat>, and then, in the read/write watcher, run the C method +on the timeout. + + +=item $w = EV::periodic $at, $interval, $callback + +=item $w = EV::periodic_ns $at, $interval, $callback Similar to EV::timer, but the time is given as an absolute point in time (C<$at>), plus an optional C<$interval>. If the C<$interval> is zero, then the callback will be called at the time -C<$at> if that is in the future, or as soon as possible if its in the +C<$at> if that is in the future, or as soon as possible if it is in the past. It will not automatically repeat. If the C<$interval> is nonzero, then the watcher will always be scheduled -to time out at the next C<$at + integer * $interval> time. +to time out at the next C<$at + N * $interval> time. This can be used to schedule a callback to run at very regular intervals, as long as the processing time is less then the interval (otherwise obviously events will be skipped). Another way to think about it (for the mathematically inclined) is that -C will try to tun the callback at the next possible time where +EV::periodic will try to run the callback at the next possible time where C<$time = $at (mod $interval)>, regardless of any time jumps. -The C variant doesn't add/start the newly created watcher. +This periodic timer is based on "wallclock time", that is, if the clock +changes (C, C etc.), then the timer will nevertheless run at +the specified time. + +The C variant doesn't start (activate) the newly created watcher. -=item my $w = EV::signal $signal, $callback +=item $w->set ($at, $interval) -=item my $w = EV::signal_ns $signal, $callback +Reconfigures the watcher, see the constructor above for details. Can be at +any time. + + +=item $w = EV::signal $signal, $callback + +=item $w = EV::signal_ns $signal, $callback Call the callback when $signal is received (the signal can be specified -by number or by name, just as with kill or %SIG). Signal watchers are -persistent no natter what. +by number or by name, just as with kill or %SIG). EV will grab the signal for the process (the kernel only allows one -component to receive signals) when you start a signal watcher, and -removes it again when you stop it. Pelr does the same when you add/remove -callbacks to %SIG, so watch out. +component to receive a signal at a time) when you start a signal watcher, +and removes it again when you stop it. Perl does the same when you +add/remove callbacks to %SIG, so watch out. -Unfortunately, only one handler can be registered per signal. Screw -libevent. +You can have as many signal watchers per signal as you want. -The C variant doesn't add/start the newly created watcher. +The C variant doesn't start (activate) the newly created watcher. -=back +=item $w->set ($signal) -=head1 THE EV::Event CLASS +Reconfigures the watcher, see the constructor above for details. Can be at +any time. -All EV functions creating an event watcher (designated by C -above) support the following methods on the returned watcher object: -=over 4 +=item $w = EV::child $pid, $callback -=item $w->add ($timeout) +=item $w = EV::child_ns $pid, $callback -Stops and (re-)starts the event watcher, setting the optional timeout to -the given value, or clearing the timeout if none is given. +Call the callback when a status change for pid C<$pid> (or any pid +if C<$pid> is 0) has been received. More precisely: when the process +receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all +changed/zombie children and call the callback. -=item $w->start +Unlike all other callbacks, this callback will be called with an +additional third argument which is the exit status. See the C +function for details. -Stops and (re-)starts the event watcher without touching the timeout. +You can have as many pid watchers per pid as you want. -=item $w->del +The C variant doesn't start (activate) the newly created watcher. -=item $w->stop +=item $w->set ($pid) -Stop the event watcher if it was started. +Reconfigures the watcher, see the constructor above for details. Can be at +any time. -=item $current_callback = $w->cb -=item $old_callback = $w->cb ($new_callback) +=item $w = EV::idle $callback -Return the previously set callback and optionally set a new one. +=item $w = EV::idle_ns $callback -=item $current_fh = $w->fh +Call the callback when there are no pending io, timer/periodic, signal or +child events, i.e. when the process is idle. -=item $old_fh = $w->fh ($new_fh) +The process will not block as long as any idle watchers are active, and +they will be called repeatedly until stopped. -Returns the previously set filehandle and optionally set a new one (also -clears the EV::SIGNAL flag when setting a filehandle). +The C variant doesn't start (activate) the newly created watcher. -=item $current_signal = $w->signal -=item $old_signal = $w->signal ($new_signal) +=item $w = EV::prepare $callback -Returns the previously set signal number and optionally set a new one (also sets -the EV::SIGNAL flag when setting a signal). +=item $w = EV::prepare_ns $callback -=item $current_eventmask = $w->events +Call the callback just before the process would block. You can still +create/modify any watchers at this point. -=item $old_eventmask = $w->events ($new_eventmask) +See the EV::check watcher, below, for explanations and an example. -Returns the previously set event mask and optionally set a new one. +The C variant doesn't start (activate) the newly created watcher. + + +=item $w = EV::check $callback + +=item $w = EV::check_ns $callback + +Call the callback just after the process wakes up again (after it has +gathered events), but before any other callbacks have been invoked. + +This is used to integrate other event-based software into the EV +mainloop: You register a prepare callback and in there, you create io and +timer watchers as required by the other software. Here is a real-world +example of integrating Net::SNMP (with some details left out): + + our @snmp_watcher; + + our $snmp_prepare = EV::prepare sub { + # do nothing unless active + $dispatcher->{_event_queue_h} + or return; + + # make the dispatcher handle any outstanding stuff + + # create an IO watcher for each and every socket + @snmp_watcher = ( + (map { EV::io $_, EV::READ, sub { } } + keys %{ $dispatcher->{_descriptors} }), + ); -=item $w->timeout ($after, $repeat) + # if there are any timeouts, also create a timer + push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { } + if $event->[Net::SNMP::Dispatcher::_ACTIVE]; + }; -Resets the timeout (see C for details). +The callbacks are irrelevant, the only purpose of those watchers is +to wake up the process as soon as one of those events occurs (socket +readable, or timer timed out). The corresponding EV::check watcher will then +clean up: -=item $w->timeout_abs ($at, $interval) + our $snmp_check = EV::check sub { + # destroy all watchers + @snmp_watcher = (); -Resets the timeout (see C for details). + # make the dispatcher handle any new stuff + }; -=item $w->priority_set ($priority) +The callbacks of the created watchers will not be called as the watchers +are destroyed before this cna happen (remember EV::check gets called +first). -Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI). +The C variant doesn't start (activate) the newly created watcher. =back =head1 THREADS Threads are not supported by this in any way. Perl pseudo-threads is evil -and must die. +stuff and must die. =cut @@ -314,8 +444,7 @@ =head1 SEE ALSO - L, L, L, L. - L. + L, L. =head1 AUTHOR