--- cvsroot/EV/EV.pm 2007/10/29 07:24:37 1.10 +++ cvsroot/EV/EV.pm 2008/07/08 18:53:11 1.100 @@ -1,269 +1,1064 @@ =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 - - my $w = EV::timer 2, 0, sub { - warn "is called after 2s"; - }; - - my $w = EV::timer 2, 1, sub { - warn "is called roughly every 2s (repeat = 1)"; - }; - - undef $w; # destroy event watcher again - - # IO - - my $w = EV::timer_abs 0, 60, sub { - warn "is called every minute, on the minute, exactly"; - }; - - my $w = EV::io \*STDIN, EV::READ | EV::PERSIST, sub { - my ($w, $events) = @_; # all callbacks get the watcher object and event mask - if ($events & EV::TIMEOUT) { - warn "nothing received on stdin for 10 seconds, retrying"; - } else { - warn "stdin is readable, you entered: ", ; - } - }; - $w->timeout (10); - - # MAINLOOP - EV::dispatch; # loop as long as watchers are active - EV::loop; # the same thing - EV::loop EV::LOOP_ONCE; - EV::loop EV::LOOP_ONSHOT; + use EV; + + # TIMERS + + my $w = EV::timer 2, 0, sub { + warn "is called after 2s"; + }; + + my $w = EV::timer 2, 2, sub { + warn "is called roughly every 2s (repeat = 2)"; + }; + + undef $w; # destroy event watcher again + + my $w = EV::periodic 0, 60, 0, sub { + warn "is called every minute, on the minute, exactly"; + }; + + # IO + + my $w = EV::io *STDIN, EV::READ, sub { + my ($w, $revents) = @_; # all callbacks receive the watcher and event mask + warn "stdin is readable, you entered: ", ; + }; + + # SIGNALS + + my $w = EV::signal 'QUIT', sub { + warn "sigquit received\n"; + }; + + # CHILD/PID STATUS CHANGES + + my $w = EV::child 666, 0, sub { + my ($w, $revents) = @_; + my $status = $w->rstatus; + }; + + # STAT CHANGES + my $w = EV::stat "/etc/passwd", 10, sub { + my ($w, $revents) = @_; + warn $w->path, " has changed somehow.\n"; + }; + + # MAINLOOP + EV::loop; # loop until EV::unloop is called or all watchers stop + 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 libevent -(L). You probably should acquaint -yourself with its documentation and source code to be able to use this -module fully. - -Please note thta this module disables the libevent EPOLL method by -default, see BUGS, below, if you need to enable it. +This module provides an interface to libev +(L). While the documentation +below is comprehensive, one might also consult the documentation of libev +itself (L) for more +subtle details on watcher semantics or some discussion on the available +backends, or how to force a specific backend with C, or just +about in any case because it has much more detailed information. + +This module is very fast and scalable. It is actually so fast that you +can use it through the L module, stay portable to other event +loops (if you don't rely on any watcher types not available through it) +and still be faster than with any other event loop currently supported in +Perl. =cut package EV; +no warnings; use strict; BEGIN { - our $VERSION = '0.02'; + our $VERSION = '3.43'; use XSLoader; XSLoader::load "EV", $VERSION; } -=head1 BASIC INTERFACE +@EV::IO::ISA = +@EV::Timer::ISA = +@EV::Periodic::ISA = +@EV::Signal::ISA = +@EV::Child::ISA = +@EV::Stat::ISA = +@EV::Idle::ISA = +@EV::Prepare::ISA = +@EV::Check::ISA = +@EV::Embed::ISA = +@EV::Fork::ISA = +@EV::Async::ISA = + "EV::Watcher"; + +@EV::Loop::Default::ISA = "EV::Loop"; + +=head1 EVENT LOOPS + +EV supports multiple event loops: There is a single "default event loop" +that can handle everything including signals and child watchers, and any +number of "dynamic event loops" that can use different backends (with +various limitations), but no child and signal watchers. + +You do not have to do anything to create the default event loop: When +the module is loaded a suitable backend is selected on the premise of +selecting a working backend (which for example rules out kqueue on most +BSDs). Modules should, unless they have "special needs" always use the +default loop as this is fastest (perl-wise), best supported by other +modules (e.g. AnyEvent or Coro) and most portable event loop. + +For specific programs you can create additional event loops dynamically. + +If you want to take avdantage of kqueue (which often works properly for +sockets only) even though the default loop doesn't enable it, you can +I a kqueue loop into the default loop: running the default loop +will then also service the kqueue loop to some extent. See the example in +the section about embed watchers for an example on how to achieve that. =over 4 -=item $EV::NPRI +=item $loop = new EV::loop [$flags] + +Create a new event loop as per the specified flags. Please refer to the +C function description in the libev documentation +(L) +for more info. + +The loop will automatically be destroyed when it is no longer referenced +by any watcher and the loop object goes out of scope. + +Using C is recommended, as only the default event loop +is protected by this module. + +=item $loop->loop_fork + +Must be called after a fork in the child, before entering or continuing +the event loop. An alternative is to use C which calls +this function automatically, at some performance loss (refer to the libev +documentation). + +=item $loop->loop_verify -How many priority levels are available. +Calls C to make internal consistency checks (for debugging +libev) and abort the program if any data structures were found to be +corrupted. + +=item $loop = EV::default_loop [$flags] + +Return the default loop (which is a singleton object). Since this module +already creates the default loop with default flags, specifying flags here +will not have any effect unless you destroy the default loop first, which +isn't supported. So in short: don't do it, and if you break it, you get to +keep the pieces. + +=back + + +=head1 BASIC INTERFACE + +=over 4 =item $EV::DIED Must contain a reference to a function that is called when a callback -throws an exception (with $@ containing thr error). The default prints an +throws an exception (with $@ containing the error). The default prints an informative message and continues. If this callback throws an exception it will be silently ignored. +=item $flags = EV::supported_backends + +=item $flags = EV::recommended_backends + +=item $flags = EV::embeddable_backends + +Returns the set (see C flags) of backends supported by this +instance of EV, the set of recommended backends (supposed to be good) for +this platform and the set of embeddable backends (see EMBED WATCHERS). + +=item EV::sleep $seconds + +Block the process for the given number of (fractional) seconds. + +=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. +=item $time = $loop->now -=item $version = EV::version +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 $method = EV::method +=item $backend = EV::backend -Return version string and event polling method used. +=item $backend = $loop->backend -=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT +Returns an integer describing the backend used by libev (EV::METHOD_SELECT +or EV::METHOD_EPOLL). -=item EV::loopexit $after +=item EV::loop [$flags] -Exit any active loop or dispatch after C<$after> seconds or immediately if -C<$after> is missing or zero. +=item $loop->loop ([$flags]) -=item EV::dispatch +Begin checking for events and calling callbacks. It returns when a +callback calls EV::unloop. -Same as C. +The $flags argument can be one of the following: -=item EV::event $callback + 0 as above + EV::LOOP_ONESHOT block at most once (wait, but do not loop) + EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) -Creates a new event watcher waiting for nothing, calling the given callback. +=item EV::unloop [$how] -=item my $w = EV::io $fileno_or_fh, $eventmask, $callback +=item $loop->unloop ([$how]) -=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback +When called with no arguments or an argument of EV::UNLOOP_ONE, makes the +innermost call to EV::loop return. -As long as the returned watcher object is alive, call the C<$callback> -when the events specified in C<$eventmask> happen. Initially, the timeout -is disabled. +When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as +fast as possible. + +=item $count = EV::loop_count + +=item $count = $loop->loop_count + +Return the number of times the event loop has polled for new +events. Sometiems useful as a generation counter. + +=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) + +=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) + +This function rolls together an I/O and a timer watcher for a single +one-shot event without the need for managing a watcher object. + +If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events> +must be a bitset containing either C, C or C, indicating the type of I/O event you want to wait for. If +you do not want to wait for some I/O event, specify C for +C<$fh_or_undef> and C<0> for C<$events>). + +If timeout is C or negative, then there will be no +timeout. Otherwise a EV::timer with this value will be started. + +When an error occurs or either the timeout or I/O watcher triggers, then +the callback will be called with the received event set (in general +you can expect it to be a combination of C, C, +C and C). + +EV::once doesn't return anything: the watchers stay active till either +of them triggers, then they will be stopped and freed, and the callback +invoked. + +=item EV::feed_fd_event ($fd, $revents) + +=item $loop->feed_fd_event ($fd, $revents) + +Feed an event on a file descriptor into EV. EV will react to this call as +if the readyness notifications specified by C<$revents> (a combination of +C and C) happened on the file descriptor C<$fd>. + +=item EV::feed_signal_event ($signal) + +Feed a signal event into EV. EV will react to this call as if the signal +specified by C<$signal> had occured. + +=item EV::set_io_collect_interval $time + +=item $loop->set_io_collect_interval ($time) + +=item EV::set_timeout_collect_interval $time + +=item $loop->set_timeout_collect_interval ($time) + +These advanced functions set the minimum block interval when polling for I/O events and the minimum +wait interval for timer events. See the libev documentation at +L for +a more detailed discussion. + +=back + + +=head1 WATCHER OBJECTS + +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 now be readable without blocking!\n" + }; + +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 I/O 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 destroyed, so you I to keep the watcher objects returned by +the constructors. + +Also, all methods changing some aspect of a watcher (->set, ->priority, +->fh and so on) automatically stop and start it again if it is active, +which means pending events get lost. + +=head2 COMMON WATCHER METHODS + +This section lists methods common to all watchers. + +=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 whether the watcher was active or not. + +=item $bool = $w->is_active + +Returns true if the watcher is active, false otherwise. + +=item $current_data = $w->data + +=item $old_data = $w->data ($new_data) + +Queries a freely usable data scalar on the watcher and optionally changes +it. This is a way to associate custom data with a watcher: + + my $w = EV::timer 60, 0, sub { + warn $_[0]->data; + }; + $w->data ("print me!"); + +=item $current_cb = $w->cb + +=item $old_cb = $w->cb ($new_cb) + +Queries the callback on the watcher and optionally changes it. You can do +this at any time without the watcher restarting. + +=item $current_priority = $w->priority + +=item $old_priority = $w->priority ($new_priority) -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. +Queries the priority on the watcher and optionally changes it. Pending +watchers with higher priority will be invoked first. The valid range of +priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default +-2). If the priority is outside this range it will automatically be +normalised to the nearest valid priority. -If you want a timeout to occur only after a specific time of inactivity, set -a repeating timeout and do NOT use EV::PERSIST. +The default priority of any newly-created watcher is 0. -Eventmask can be one or more of these constants ORed together: +Note that the priority semantics have not yet been fleshed out and are +subject to almost certain change. + +=item $w->invoke ($revents) + +Call the callback *now* with the given event mask. + +=item $w->feed_event ($revents) + +Feed some events on this watcher into EV. EV will react to this call as if +the watcher had received the given C<$revents> mask. + +=item $revents = $w->clear_pending + +If the watcher is pending, this function clears its pending status and +returns its C<$revents> bitset (as if its callback was invoked). If the +watcher isn't pending it does nothing and returns C<0>. + +=item $previous_state = $w->keepalive ($bool) + +Normally, C will return when there are no active watchers +(which is a "deadlock" because no progress can be made anymore). This is +convinient because it allows you to start your watchers (and your jobs), +call C once and when it returns you know that all your jobs are +finished (or they forgot to register some watchers for their task :). + +Sometimes, however, this gets in your way, for example when the module +that calls C (usually the main program) is not the same module +as a long-living watcher (for example a DNS client module written by +somebody else even). Then you might want any outstanding requests to be +handled, but you would not want to keep C from returning just +because you happen to have this long-running UDP port watcher. + +In this case you can clear the keepalive status, which means that even +though your watcher is active, it won't keep C from returning. + +The initial value for keepalive is true (enabled), and you cna change it +any time. + +Example: Register an I/O watcher for some UDP socket but do not keep the +event loop from running just because of that watcher. + + my $udp_socket = ... + my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; + $udp_watcher->keepalive (0); + +=item $loop = $w->loop + +Return the loop that this watcher is attached to. + +=back + + +=head1 WATCHER TYPES + +Each of the following subsections describes a single watcher type. + +=head3 I/O WATCHERS - is this file descriptor readable or writable? + +=over 4 + +=item $w = EV::io $fileno_or_fh, $eventmask, $callback + +=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback + +=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback) + +=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback) + +As long as the returned watcher object is alive, call the C<$callback> +when at least one of events specified in C<$eventmask> occurs. + +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 $w->set ($fileno_or_fh, $eventmask) + +Reconfigures the watcher, see the constructor above for details. Can be +called at any time. + +=item $current_fh = $w->fh + +=item $old_fh = $w->fh ($new_fh) + +Returns the previously set filehandle and optionally set a new one. -=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback +=item $current_eventmask = $w->events + +=item $old_eventmask = $w->events ($new_eventmask) + +Returns the previously set event mask and optionally set a new one. -=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback +=back + + +=head3 TIMER WATCHERS - relative and optionally repeating timeouts + +=over 4 -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 $w = EV::timer $after, $repeat, $callback -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 $w = EV::timer_ns $after, $repeat, $callback -This has the effect of timing out after the specified period of inactivity -has happened. +=item $w = $loop->timer ($after, $repeat, $callback) -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 $w = $loop->timer_ns ($after, $repeat, $callback) -=item my $w = EV::timer $after, $repeat, $callback +Calls the callback after C<$after> seconds (which may be fractional). If +C<$repeat> is non-zero, the timer will be restarted (with the $repeat +value as $after) after the callback returns. -=item my $w = EV::timer_ns $after, $repeat, $callback +This means that the callback would be called roughly after C<$after> +seconds, and then every C<$repeat> seconds. The timer does his best not +to drift, but it will not invoke the timer more often then once per event +loop iteration, and might drift in other cases. If that isn't acceptable, +look at EV::periodic, which can provide long-term stable timers. -Calls the callback after C<$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. +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. -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::timer_abs $at, $interval, $callback +=item $w->set ($after, $repeat) -=item my $w = EV::timer_abs_ns $at, $interval, $callback +Reconfigures the watcher, see the constructor above for details. Can be called at +any time. -Similar to EV::timer, but the time is given as an absolute point in time -(C<$at>), plus an optional C<$interval>. +=item $w->again -If the C<$interval> is zero, then the callback will be called at the time -C<$at> if that is in the future, or as soon as possible if its in the -past. It will not automatically repeat. +Similar to the C method, but has special semantics for repeating timers: -If the C<$interval> is nonzero, then the watcher will always be scheduled -to time out at the next C<$at + integer * $interval> time. +If the timer is active and non-repeating, it will be stopped. -This can be used to schedule a callback to run at very regular intervals, -as long as the processing time is less then the interval (otherwise -obviously events will be skipped). +If the timer is active and repeating, reset the timeout to occur +C<$repeat> seconds after now. + +If the timer is inactive and repeating, start it using the repeat value. + +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. + +=back + + +=head3 PERIODIC WATCHERS - to cron or not to cron? + +=over 4 + +=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback + +=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback + +=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback) + +=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback) + +Similar to EV::timer, but is not based on relative timeouts but on +absolute times. Apart from creating "simple" timers that trigger "at" the +specified time, it can also be used for non-drifting absolute timers and +more complex, cron-like, setups that are not adversely affected by time +jumps (i.e. when the system clock is changed by explicit date -s or other +means such as ntpd). It is also the most complex watcher type in EV. + +It has three distinct "modes": + +=over 4 + +=item * absolute timer ($interval = $reschedule_cb = 0) + +This time simply fires at the wallclock time C<$at> and doesn't repeat. It +will not adjust when a time jump occurs, that is, if it is to be run +at January 1st 2011 then it will run when the system time reaches or +surpasses this time. + +=item * repeating interval timer ($interval > 0, $reschedule_cb = 0) + +In this mode the watcher will always be scheduled to time out at the +next C<$at + N * $interval> time (for some integer N) and then repeat, +regardless of any time jumps. + +This can be used to create timers that do not drift with respect to system +time: + + my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; + +That doesn't mean there will always be 3600 seconds in between triggers, +but only that the the clalback will be called when the system time shows a +full hour (UTC). Another way to think about it (for the mathematically inclined) is that -C will try to tun the callback at the next possible time where -C<$time = $at (mod $interval)>, regardless of any time jumps. +EV::periodic will try to run the callback in this mode at the next +possible time where C<$time = $at (mod $interval)>, regardless of any time +jumps. + +=item * manual reschedule mode ($reschedule_cb = coderef) + +In this mode $interval and $at are both being ignored. Instead, each +time the periodic watcher gets scheduled, the reschedule callback +($reschedule_cb) will be called with the watcher as first, and the current +time as second argument. + +I. If +you need to stop it, return 1e30 and stop it afterwards. You may create +and start a C watcher for this task. + +It must return the next time to trigger, based on the passed time value +(that is, the lowest time value larger than or equal to to the second +argument). It will usually be called just before the callback will be +triggered, but might be called at other times, too. + +This can be used to create very complex timers, such as a timer that +triggers on each midnight, local time (actually 24 hours after the last +midnight, to keep the example simple. If you know a way to do it correctly +in about the same space (without requiring elaborate modules), drop me a +note :): + + my $daily = EV::periodic 0, 0, sub { + my ($w, $now) = @_; + + use Time::Local (); + my (undef, undef, undef, $d, $m, $y) = localtime $now; + 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y + }, sub { + print "it's midnight or likely shortly after, now\n"; + }; + +=back + +The C variant doesn't start (activate) the newly created watcher. -The C variant doesn't add/start the newly created watcher. +=item $w->set ($at, $interval, $reschedule_cb) -=item my $w = EV::signal $signum, $callback +Reconfigures the watcher, see the constructor above for details. Can be called at +any time. -=item my $w = EV::signal_ns $signum, $callback +=item $w->again -Call the callback when signal $signum is received. +Simply stops and starts the watcher again. -The C variant doesn't add/start the newly created watcher. +=item $time = $w->at + +Return the time that the watcher is expected to trigger next. =back -=head1 THE EV::Event CLASS -All EV functions creating an event watcher (designated by C -above) support the following methods on the returned watcher object: +=head3 SIGNAL WATCHERS - signal me when a signal gets signalled! =over 4 -=item $w->add ($timeout) +=item $w = EV::signal $signal, $callback -Stops and (re-)starts the event watcher, setting the optional timeout to -the given value, or clearing the timeout if none is given. +=item $w = EV::signal_ns $signal, $callback -=item $w->start +Call the callback when $signal is received (the signal can be specified by +number or by name, just as with C or C<%SIG>). -Stops and (re-)starts the event watcher without touching the timeout. +EV will grab the signal for the process (the kernel only allows one +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 C<%SIG>, so watch out. -=item $w->del +You can have as many signal watchers per signal as you want. -=item $w->stop +The C variant doesn't start (activate) the newly created watcher. -Stop the event watcher if it was started. +=item $w->set ($signal) -=item $current_callback = $w->cb +Reconfigures the watcher, see the constructor above for details. Can be +called at any time. -=item $old_callback = $w->cb ($new_callback) +=item $current_signum = $w->signal -Return the previously set callback and optionally set a new one. +=item $old_signum = $w->signal ($new_signal) -=item $current_fh = $w->fh +Returns the previously set signal (always as a number not name) and +optionally set a new one. -=item $old_fh = $w->fh ($new_fh) +=back -Returns the previously set filehandle and optionally set a new one (also -clears the EV::SIGNAL flag when setting a filehandle). -=item $current_signal = $w->signal +=head3 CHILD WATCHERS - watch out for process status changes -=item $old_signal = $w->signal ($new_signal) +=over 4 -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::child $pid, $trace, $callback -=item $current_eventmask = $w->events +=item $w = EV::child_ns $pid, $trace, $callback -=item $old_eventmask = $w->events ($new_eventmask) +=item $w = $loop->child ($pid, $trace, $callback) + +=item $w = $loop->child_ns ($pid, $trace, $callback) + +Call the callback when a status change for pid C<$pid> (or any pid +if C<$pid> is 0) has been received (a status change happens when the +process terminates or is killed, or, when trace is true, additionally when +it is stopped or continued). More precisely: when the process receives +a C, EV will fetch the outstanding exit/wait status for all +changed/zombie children and call the callback. + +It is valid (and fully supported) to install a child watcher after a child +has exited but before the event loop has started its next iteration (for +example, first you C, then the new child process might exit, and +only then do you install a child watcher in the parent for the new pid). + +You can access both exit (or tracing) status and pid by using the +C and C methods on the watcher object. + +You can have as many pid watchers per pid as you want, they will all be +called. + +The C variant doesn't start (activate) the newly created watcher. + +=item $w->set ($pid, $trace) + +Reconfigures the watcher, see the constructor above for details. Can be called at +any time. + +=item $current_pid = $w->pid + +Returns the previously set process id and optionally set a new one. + +=item $exit_status = $w->rstatus + +Return the exit/wait status (as returned by waitpid, see the waitpid entry +in perlfunc). + +=item $pid = $w->rpid + +Return the pid of the awaited child (useful when you have installed a +watcher for all pids). + +=back + + +=head3 STAT WATCHERS - did the file attributes just change? + +=over 4 + +=item $w = EV::stat $path, $interval, $callback + +=item $w = EV::stat_ns $path, $interval, $callback + +=item $w = $loop->stat ($path, $interval, $callback) + +=item $w = $loop->stat_ns ($path, $interval, $callback) + +Call the callback when a file status change has been detected on +C<$path>. The C<$path> does not need to exist, changing from "path exists" +to "path does not exist" is a status change like any other. + +The C<$interval> is a recommended polling interval for systems where +OS-supported change notifications don't exist or are not supported. If +you use C<0> then an unspecified default is used (which is highly +recommended!), which is to be expected to be around five seconds usually. + +This watcher type is not meant for massive numbers of stat watchers, +as even with OS-supported change notifications, this can be +resource-intensive. + +The C variant doesn't start (activate) the newly created watcher. + +=item ... = $w->stat + +This call is very similar to the perl C built-in: It stats (using +C) the path specified in the watcher and sets perls stat cache (as +well as EV's idea of the current stat values) to the values found. + +In scalar context, a boolean is return indicating success or failure of +the stat. In list context, the same 13-value list as with stat is returned +(except that the blksize and blocks fields are not reliable). + +In the case of an error, errno is set to C (regardless of the +actual error value) and the C value is forced to zero (if the stat +was successful then nlink is guaranteed to be non-zero). + +See also the next two entries for more info. + +=item ... = $w->attr + +Just like C<< $w->stat >>, but without the initial stat'ing: this returns +the values most recently detected by EV. See the next entry for more info. + +=item ... = $w->prev + +Just like C<< $w->stat >>, but without the initial stat'ing: this returns +the previous set of values, before the change. + +That is, when the watcher callback is invoked, C<< $w->prev >> will be set +to the values found I a change was detected, while C<< $w->attr >> +returns the values found leading to the change detection. The difference (if any) +between C and C is what triggered the callback. + +If you did something to the filesystem object and do not want to trigger +yet another change, you can call C to update EV's idea of what the +current attributes are. + +=item $w->set ($path, $interval) + +Reconfigures the watcher, see the constructor above for details. Can be +called at any time. + +=item $current_path = $w->path + +=item $old_path = $w->path ($new_path) + +Returns the previously set path and optionally set a new one. + +=item $current_interval = $w->interval + +=item $old_interval = $w->interval ($new_interval) + +Returns the previously set interval and optionally set a new one. Can be +used to query the actual interval used. + +=back + + +=head3 IDLE WATCHERS - when you've got nothing better to do... + +=over 4 + +=item $w = EV::idle $callback + +=item $w = EV::idle_ns $callback + +=item $w = $loop->idle ($callback) + +=item $w = $loop->idle_ns ($callback) + +Call the callback when there are no other pending watchers of the same or +higher priority (excluding check, prepare and other idle watchers of the +same or lower priority, of course). They are called idle watchers because +when the watcher is the highest priority pending event in the process, the +process is considered to be idle at that priority. + +If you want a watcher that is only ever called when I other events are +outstanding you have to set the priority to C. + +The process will not block as long as any idle watchers are active, and +they will be called repeatedly until stopped. + +For example, if you have idle watchers at priority C<0> and C<1>, and +an I/O watcher at priority C<0>, then the idle watcher at priority C<1> +and the I/O watcher will always run when ready. Only when the idle watcher +at priority C<1> is stopped and the I/O watcher at priority C<0> is not +pending with the C<0>-priority idle watcher be invoked. + +The C variant doesn't start (activate) the newly created watcher. + +=back -Returns the previously set event mask and optionally set a new one. -=item $w->timeout ($after, $repeat) +=head3 PREPARE WATCHERS - customise your event loop! -Resets the timeout (see C for details). +=over 4 + +=item $w = EV::prepare $callback + +=item $w = EV::prepare_ns $callback + +=item $w = $loop->prepare ($callback) + +=item $w = $loop->prepare_ns ($callback) + +Call the callback just before the process would block. You can still +create/modify any watchers at this point. + +See the EV::check watcher, below, for explanations and an example. + +The C variant doesn't start (activate) the newly created watcher. + +=back + + +=head3 CHECK WATCHERS - customise your event loop even more! + +=over 4 + +=item $w = EV::check $callback + +=item $w = EV::check_ns $callback + +=item $w = $loop->check ($callback) + +=item $w = $loop->check_ns ($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 + ... not shown + + # create an I/O watcher for each and every socket + @snmp_watcher = ( + (map { EV::io $_, EV::READ, sub { } } + keys %{ $dispatcher->{_descriptors} }), + + EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] + ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0), + 0, sub { }, + ); + }; + +The callbacks are irrelevant (and are not even being called), 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: + + our $snmp_check = EV::check sub { + # destroy all watchers + @snmp_watcher = (); + + # make the dispatcher handle any new stuff + ... not shown + }; + +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). + +The C variant doesn't start (activate) the newly created watcher. + +=back + + +=head3 FORK WATCHERS - the audacity to resume the event loop after a fork + +Fork watchers are called when a C was detected. The invocation +is done before the event loop blocks next and before C watchers +are being called, and only in the child after the fork. + +=over 4 -=item $w->timeout_abs ($at, $interval) +=item $w = EV::fork $callback -Resets the timeout (see C for details). +=item $w = EV::fork_ns $callback -=item $w->priority_set ($priority) +=item $w = $loop->fork ($callback) -Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI). +=item $w = $loop->fork_ns ($callback) + +Call the callback before the event loop is resumed in the child process +after a fork. + +The C variant doesn't start (activate) the newly created watcher. =back -=head1 BUGS -Lots. Libevent itself isn't well tested and rather buggy, and this module -is quite new at the moment. +=head3 EMBED WATCHERS - when one backend isn't enough... + +This is a rather advanced watcher type that lets you embed one event loop +into another (currently only IO events are supported in the embedded +loop, other types of watchers might be handled in a delayed or incorrect +fashion and must not be used). + +See the libev documentation at +L +for more details. + +In short, this watcher is most useful on BSD systems without working +kqueue to still be able to handle a large number of sockets: + + my $socket_loop; + + # check wether we use SELECT or POLL _and_ KQUEUE is supported + if ( + (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT)) + && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE) + ) { + # use kqueue for sockets + $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV; + } + + # use the default loop otherwise + $socket_loop ||= EV::default_loop; + +=over 4 + +=item $w = EV::embed $otherloop, $callback + +=item $w = EV::embed_ns $otherloop, $callback + +=item $w = $loop->embed ($otherloop, $callback) + +=item $w = $loop->embed_ns ($otherloop, $callback) + +Call the callback when the embedded event loop (C<$otherloop>) has any +I/O activity. The C<$callback> should alwas be specified as C in +this version of EV, which means the embedded event loop will be managed +automatically. + +The C variant doesn't start (activate) the newly created watcher. + +=back + +=head3 ASYNC WATCHERS - how to wake up another event loop + +Async watchers are provided by EV, but have little use in perl directly, as perl +neither supports threads nor direct access to signal handlers or other +contexts where they could be of value. + +It is, however, possible to use them from the XS level. + +Please see the libev documentation for further details. + +=over 4 -Please note that the epoll method is not, in general, reliable in programs -that use fork (even if no libveent calls are being made in the forked -process). If your program behaves erratically, try setting the environment -variable C first when running the program. +=item $w = EV::async $callback -In general, if you fork, then you can only use the EV module in one of the -children. +=item $w = EV::async_ns $callback + +=item $w->send + +=item $bool = $w->async_pending + +=back + + +=head1 PERL SIGNALS + +While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour +with EV is as the same as any other C library: Perl-signals will only be +handled when Perl runs, which means your signal handler might be invoked +only the next time an event callback is invoked. + +The solution is to use EV signal watchers (see C), which will +ensure proper operations with regards to other event watchers. + +If you cannot do this for whatever reason, you can also force a watcher +to be called on every event loop iteration by installing a C +watcher: + + my $async_check = EV::check sub { }; + +This ensures that perl gets into control for a short time to handle any +pending signals, and also ensures (slightly) slower overall operation. + +=head1 THREADS + +Threads are not supported by this module in any way. Perl pseudo-threads +is evil stuff and must die. As soon as Perl gains real threads I will work +on thread support for it. + +=head1 FORK + +Most of the "improved" event delivering mechanisms of modern operating +systems have quite a few problems with fork(2) (to put it bluntly: it is +not supported and usually destructive). Libev makes it possible to work +around this by having a function that recreates the kernel state after +fork in the child. + +On non-win32 platforms, this module requires the pthread_atfork +functionality to do this automatically for you. This function is quite +buggy on most BSDs, though, so YMMV. The overhead for this is quite +negligible, because everything the function currently does is set a flag +that is checked only when the event loop gets used the next time, so when +you do fork but not use EV, the overhead is minimal. + +On win32, there is no notion of fork so all this doesn't apply, of course. =cut @@ -271,23 +1066,22 @@ warn "EV: error in callback (ignoring): $@"; }; -our $NPRI = 4; -our $BASE = init; -priority_init $NPRI; - -push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"]; +default_loop + or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?'; 1; =head1 SEE ALSO - L, L, L, L. - L. +L (asynchronous DNS), L (makes Glib/Gtk2 use EV as +event loop), L (embed Glib into EV), L (efficient +coroutines with EV), L (asynchronous SNMP), L for +event-loop agnostic and portable event driven programming. =head1 AUTHOR - Marc Lehmann - http://home.schmorp.de/ + Marc Lehmann + http://home.schmorp.de/ =cut