--- cvsroot/EV/EV.pm 2007/10/27 07:30:10 1.6 +++ cvsroot/EV/EV.pm 2007/11/24 08:28:10 1.49 @@ -1,54 +1,56 @@ =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 "nothign 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 $w = EV::child 666, sub { + my ($w, $revents) = @_; + my $status = $w->rstatus; + }; + + # 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). =cut @@ -57,128 +59,207 @@ use strict; BEGIN { - our $VERSION = '0.01'; + our $VERSION = '1.2'; use XSLoader; XSLoader::load "EV", $VERSION; } -=head1 FUNCTIONAL INTERFACE +@EV::IO::ISA = +@EV::Timer::ISA = +@EV::Periodic::ISA = +@EV::Signal::ISA = +@EV::Idle::ISA = +@EV::Prepare::ISA = +@EV::Check::ISA = +@EV::Child::ISA = "EV::Watcher"; + +=head1 BASIC INTERFACE =over 4 -=item $EV::NPRI +=item $EV::DIED -How many priority levels are available. +Must contain a reference to a function that is called when a callback +throws an exception (with $@ containing thr error). The default prints an +informative message and continues. -=item $time = EV::now +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. -Returns the time in (fractional) seconds since the epoch. +=item $time = EV::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 -Return version string and event polling method used. +Returns an integer describing the backend used by libev (EV::METHOD_SELECT +or EV::METHOD_EPOLL). -=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT +=item EV::loop [$flags] -=item EV::loopexit $after +Begin checking for events and calling callbacks. It returns when a +callback calls EV::unloop. -Exit any active loop or dispatch after C<$after> seconds or immediately if -C<$after> is missing or zero. +The $flags argument can be one of the following: -=item EV::dispatch + 0 as above + EV::LOOP_ONESHOT block at most once (wait, but do not loop) + EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) -Same as C. +=item EV::unloop [$how] -=item EV::event $callback +When called with no arguments or an argument of EV::UNLOOP_ONE, makes the +innermost call to EV::loop return. -Creates a new event watcher waiting for nothing, calling the given callback. +When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as +fast as possible. -=item my $w = EV::io $fileno_or_fh, $eventmask, $callback +=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) -=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback +This function rolls together an I/O and a timer watcher for a single +one-shot event without the need for managing a watcher object. -As long as the returned watcher object is alive, call the C<$callback> -when the events specified in C<$eventmask> happen. Initially, the timeout -is disabled. +If C<$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>). -The C variant doesn't add/start the newly created watcher. +If timeout is C or negative, then there will be no +timeout. Otherwise a EV::timer with this value will be started. -Eventmask can be one or more of these constants ORed together: +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::READ wait until read() wouldn't block anymore - EV::WRITE wait until write() wouldn't block anymore - EV::PERSIST stay active after an event occured +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 my $w = EV::timer $after, $repeat, $callback +=back -=item my $w = EV::timer_ns $after, $repeat, $callback +=head2 WATCHER -Calls the callback after C<$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. +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" + }; + +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 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 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). -The C variant doesn't add/start the newly created watcher. +=over 4 -=item my $w = EV::timer_abs $at, $interval, $callback +=item $w->start -=item my $w = EV::timer_abs_ns $at, $interval, $callback +Starts a watcher if it isn't active already. Does nothing to an already +active watcher. By default, all watchers start out in the active state +(see the description of the C<_ns> variants if you need stopped watchers). -Similar to EV::timer, but the time is given as an absolute point in time -(C<$at>), plus an optional C<$interval>. +=item $w->stop -If the C<$interval> is zero, then the callback will be called at the time -C<$at> if that is in the future, or as soon as possible if its in the -past. It will not automatically repeat. +Stop a watcher if it is active. Also clear any pending events (events that +have been received but that didn't yet result in a callback invocation), +regardless of wether the watcher was active or not. -If the C<$interval> is nonzero, then the watcher will always be scheduled -to time out at the next C<$at + integer * $interval> time. +=item $bool = $w->is_active -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). +Returns true if the watcher is active, false otherwise. -The C variant doesn't add/start the newly created watcher. +=item $current_data = $w->data -=item my $w = EV::signal $signum, $callback +=item $old_data = $w->data ($new_data) -=item my $w = EV::signal_ns $signum, $callback +Queries a freely usable data scalar on the watcher and optionally changes +it. This is a way to associate custom data with a watcher: -Call the callback when signal $signum is received. + my $w = EV::timer 60, 0, sub { + warn $_[0]->data; + }; + $w->data ("print me!"); -The C variant doesn't add/start the newly created watcher. +=item $current_cb = $w->cb -=back +=item $old_cb = $w->cb ($new_cb) -=head1 THE EV::Event CLASS +Queries the callback on the watcher and optionally changes it. You can do +this at any time without the watcher restarting. -All EV functions creating an event watcher (designated by C -above) support the following methods on the returned watcher object: +=item $current_priority = $w->priority -=over 4 +=item $old_priority = $w->priority ($new_priority) -=item $w->add ($timeout) +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. -Stops and (re-)starts the event watcher, setting the optional timeout to -the given value, or clearing the timeout if none is given. +The default priority of any newly-created weatcher is 0. -=item $w->start +=item $w->trigger ($revents) -Stops and (re-)starts the event watcher without touching the timeout. +Call the callback *now* with the given event mask. -=item $w->del -=item $w->stop +=item $w = EV::io $fileno_or_fh, $eventmask, $callback -Stop the event watcher if it was started. +=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback -=item $current_callback = $w->cb +As long as the returned watcher object is alive, call the C<$callback> +when the events specified in C<$eventmask>. -=item $old_callback = $w->cb ($new_callback) +The $eventmask can be one or more of these constants ORed together: -Return the previously set callback and optionally set a new one. + EV::READ wait until read() wouldn't block anymore + EV::WRITE wait until write() wouldn't block anymore + +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 @@ -192,54 +273,322 @@ Returns the previously set event mask and optionally set a new one. -=item $w->timeout ($after, $repeat) -Resets the timeout (see C for details). +=item $w = EV::timer $after, $repeat, $callback + +=item $w = EV::timer_ns $after, $repeat, $callback + +Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, +the timer will be restarted (with the $repeat value as $after) after the +callback returns. -=item $w->timeout_abs ($at, $interval) +This means that the callback would be called roughly after C<$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. -Resets the timeout (see C for details). +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 $w->priority_set ($priority) +The C variant doesn't start (activate) the newly created watcher. -Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI). +=item $w->set ($after, $repeat) + +Reconfigures the watcher, see the constructor above for details. Can be at +any time. + +=item $w->again + +Similar to the C method, but has special semantics for repeating timers: + +If the timer is active and non-repeating, it will be stopped. + +If the timer is active and repeating, reset the timeout to occur +C<$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. + + +=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback + +=item $w = EV::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 * non-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 $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; + +That doesn't mean there will always be 3600 seconds in between triggers, +but only that the the clalback will be called when the system time shows a +full hour (UTC). + +Another way to think about it (for the mathematically inclined) is that +EV::periodic will try to run the callback in this mode at the next +possible time where C<$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. + +It must return the next time to trigger, based on the passed time value +(that is, the lowest time value larger than 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 -=head1 BUGS +The C variant doesn't start (activate) the newly created watcher. -Lots. Libevent itself isn't well tested and rather buggy, and this module -is quite new at the moment. +=item $w->set ($at, $interval, $reschedule_cb) -Please note that the epoll method is not, in general, reliable in -programs that use fork (even if no libveent calls are being made in the -forked process). Since this is such a common issue, this module will -force the epoll method in EV to be off *unless* the global variable -$EV::ENABLE_EPOLL is set to 1 *before* loading this module for the first -time. +Reconfigures the watcher, see the constructor above for details. Can be at +any time. -=cut +=item $w->again -our $NPRI = 4; -our $BASE; -our $ENABLE_EPOLL; - -{ - local $ENV{EVENT_NOEPOLL}; - $ENV{EVENT_NOEPOLL} = 1 unless $ENABLE_EPOLL; - $BASE = init; -} +Simply stops and starts the watcher again. + + +=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). + +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 %SIG, so watch out. + +You can have as many signal watchers per signal as you want. + +The C variant doesn't start (activate) the newly created watcher. + +=item $w->set ($signal) + +Reconfigures the watcher, see the constructor above for details. Can be at +any time. + +=item $current_signum = $w->signal + +=item $old_signum = $w->signal ($new_signal) + +Returns the previously set signal (always as a number not name) and +optionally set a new one. + + +=item $w = EV::child $pid, $callback + +=item $w = EV::child_ns $pid, $callback + +Call the callback when a status change for pid C<$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. + +You can access both 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. + +The C variant doesn't start (activate) the newly created watcher. + +=item $w->set ($pid) + +Reconfigures the watcher, see the constructor above for details. Can be at +any time. + +=item $current_pid = $w->pid + +=item $old_pid = $w->pid ($new_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). + + +=item $w = EV::idle $callback + +=item $w = EV::idle_ns $callback + +Call the callback when there are no pending io, timer/periodic, signal or +child events, i.e. when the process is idle. + +The process will not block as long as any idle watchers are active, and +they will be called repeatedly until stopped. + +The C variant doesn't start (activate) the newly created watcher. + + +=item $w = EV::prepare $callback + +=item $w = EV::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. + + +=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 + ... not shown + + # create an IO 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 + +=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 -priority_init $NPRI; +our $DIED = sub { + warn "EV: error in callback (ignoring): $@"; +}; -push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"]; +default_loop + or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1; =head1 SEE ALSO - L, L, L, L. - L. + L. =head1 AUTHOR