--- cvsroot/EV/EV.pm 2007/11/09 19:38:56 1.34 +++ cvsroot/EV/EV.pm 2007/11/28 19:22:16 1.58 @@ -12,8 +12,8 @@ warn "is called after 2s"; }; - my $w = EV::timer 2, 1, sub { - warn "is called roughly every 2s (repeat = 1)"; + my $w = EV::timer 2, 2, sub { + warn "is called roughly every 2s (repeat = 2)"; }; undef $w; # destroy event watcher again @@ -25,7 +25,7 @@ # IO my $w = EV::io *STDIN, EV::READ, sub { - my ($w, $revents) = @_; # all callbacks get the watcher object and event mask + my ($w, $revents) = @_; # all callbacks receive the watcher and event mask warn "stdin is readable, you entered: ", ; }; @@ -35,27 +35,32 @@ warn "sigquit received\n"; }; - my $w = EV::signal 3, sub { - warn "sigquit received (this is GNU/Linux, right?)\n"; - }; - # CHILD/PID STATUS CHANGES my $w = EV::child 666, sub { my ($w, $revents) = @_; - # my $pid = $w->rpid; 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::loop_done is called + 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 libev -(L). +(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. =cut @@ -64,19 +69,23 @@ use strict; BEGIN { - our $VERSION = '0.7'; + our $VERSION = '1.5'; use XSLoader; XSLoader::load "EV", $VERSION; } -@EV::Io::ISA = +@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::Child::ISA = "EV::Watcher"; +@EV::Embed::ISA = +@EV::Fork::ISA = + "EV::Watcher"; =head1 BASIC INTERFACE @@ -100,7 +109,7 @@ is the time that (relative) timers are based on, and refering to it is usually faster then calling EV::time. -=item $method = EV::ev_method +=item $method = EV::method Returns an integer describing the backend used by libev (EV::METHOD_SELECT or EV::METHOD_EPOLL). @@ -108,7 +117,7 @@ =item EV::loop [$flags] Begin checking for events and calling callbacks. It returns when a -callback calls EV::loop_done. +callback calls EV::unloop. The $flags argument can be one of the following: @@ -116,17 +125,40 @@ EV::LOOP_ONESHOT block at most once (wait, but do not loop) EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) -=item EV::loop_done [$how] +=item EV::unloop [$how] -When called with no arguments or an argument of 1, makes the innermost -call to EV::loop return. +When called with no arguments or an argument of EV::UNLOOP_ONE, makes the +innermost call to EV::loop return. -When called with an agrument of 2, all calls to EV::loop will return as +When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as fast as possible. +=item EV::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. + =back -=head2 WATCHER +=head2 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 @@ -161,14 +193,9 @@ ->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. +=head2 COMMON WATCHER 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). +This section lists methods common to all watchers. =over 4 @@ -217,19 +244,60 @@ -2). If the priority is outside this range it will automatically be normalised to the nearest valid priority. -The default priority of any newly-created weatcher is 0. +The default priority of any newly-created watcher is 0. + +Note that the priority semantics have not yet been fleshed out and are +subject to almost certain change. =item $w->trigger ($revents) Call the callback *now* with the given event mask. +=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 you 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 IO 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); + +=back + + +=head2 WATCHER TYPES + +Each of the following subsections describes a single watcher type. + +=head3 IO 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, $callback As long as the returned watcher object is alive, call the C<$callback> -when the events specified in C<$eventmask>. +when at least one of events specified in C<$eventmask> occurs. The $eventmask can be one or more of these constants ORed together: @@ -255,21 +323,28 @@ Returns the previously set event mask and optionally set a new one. +=back + + +=head3 TIMER WATCHERS - relative and optionally repeating timeouts + +=over 4 =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 $after) after the -callback returns. +Calls the callback after C<$after> seconds (which may be fractional). If +C<$repeat> is non-zero, the timer will be restarted (with the $repeat +value as $after) after the callback returns. This means that the callback would be called roughly after C<$after> -seconds, and then every C<$repeat> seconds. "Roughly" because the time of -callback processing is not taken into account, so the timer will slowly -drift. If that isn't acceptable, look at EV::periodic. +seconds, and then every C<$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. -The timer is based on a monotonic clock, that is if somebody is sitting +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. @@ -277,19 +352,19 @@ =item $w->set ($after, $repeat) -Reconfigures the watcher, see the constructor above for details. Can be at +Reconfigures the watcher, see the constructor above for details. Can be called 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 active and non-repeating, it will be stopped. - -If the timer is in active and repeating, start it. +If the timer is inactive and repeating, start it using the repeat value. Otherwise do nothing. @@ -298,6 +373,12 @@ 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, $callback @@ -343,10 +424,10 @@ =item * manual reschedule mode ($reschedule_cb = coderef) -In this mode $interval and $at are both being ignored. Instead, each time -the periodic watcher gets scheduled, the first callback ($reschedule_cb) -will be called with the watcher as first, and the current time as second -argument. +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 @@ -379,25 +460,31 @@ =item $w->set ($at, $interval, $reschedule_cb) -Reconfigures the watcher, see the constructor above for details. Can be at +Reconfigures the watcher, see the constructor above for details. Can be called at any time. =item $w->again Simply stops and starts the watcher again. +=back + + +=head3 SIGNAL WATCHERS - signal me when a signal gets signalled! + +=over 4 =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). +Call the callback when $signal is received (the signal can be specified by +number or by name, just as with C or C<%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. +add/remove callbacks to C<%SIG>, so watch out. You can have as many signal watchers per signal as you want. @@ -405,8 +492,8 @@ =item $w->set ($signal) -Reconfigures the watcher, see the constructor above for details. Can be at -any time. +Reconfigures the watcher, see the constructor above for details. Can be +called at any time. =item $current_signum = $w->signal @@ -415,26 +502,38 @@ Returns the previously set signal (always as a number not name) and optionally set a new one. +=back + + +=head3 CHILD WATCHERS - watch out for process status changes + +=over 4 =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<$pid> is 0) has been received. More precisely: when the process -receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all +Call the callback when a status change for pid C<$pid> (or any pid if +C<$pid> is 0) has been received. More precisely: when the process receives +a C, 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. +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. +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) -Reconfigures the watcher, see the constructor above for details. Can be at +Reconfigures the watcher, see the constructor above for details. Can be called at any time. =item $current_pid = $w->pid @@ -453,6 +552,91 @@ 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, $callback + +Call the callback when a file status change has been detected on +C<$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 @@ -466,6 +650,12 @@ The C variant doesn't start (activate) the newly created watcher. +=back + + +=head3 PREPARE WATCHERS - customise your event loop! + +=over 4 =item $w = EV::prepare $callback @@ -478,6 +668,12 @@ 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 @@ -499,28 +695,30 @@ 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} }), - ); - # if there are any timeouts, also create a timer - push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { } - if $event->[Net::SNMP::Dispatcher::_ACTIVE]; + EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] + ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0), + 0, sub { }, + ); }; -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: +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 @@ -531,10 +729,49 @@ =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 = EV::fork $callback + +=item $w = EV::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 THREADS -Threads are not supported by this in any way. Perl pseudo-threads is evil -stuff and must die. +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 @@ -549,7 +786,7 @@ =head1 SEE ALSO - L, L. +L. =head1 AUTHOR