--- cvsroot/EV/EV.pm 2007/11/24 16:20:30 1.52 +++ cvsroot/EV/EV.pm 2010/03/16 17:11:48 1.126 @@ -4,66 +4,84 @@ =head1 SYNOPSIS - 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"; - }; + 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 - # CHILD/PID STATUS CHANGES - - my $w = EV::child 666, sub { - my ($w, $revents) = @_; - my $status = $w->rstatus; - }; + my $w = EV::child 666, 0, sub { + my ($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 + # 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 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. +below is comprehensive, one might also consult the documentation of +libev itself (L or +F) 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. + +=head2 MODULE EXPORTS + +This module does not export any symbols. =cut package EV; -use strict; +use common::sense; BEGIN { - our $VERSION = '1.3'; + our $VERSION = '4.00'; use XSLoader; XSLoader::load "EV", $VERSION; } @@ -72,10 +90,80 @@ @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::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 advantage 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 $loop = new EV::Loop [$flags] + +Create a new event loop as per the specified flags. Please refer to +the C function description in the libev documentation +(L, +or locally-installed as F manpage) 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. + +If you are not embedding the loop, then Using C +is recommended, as only the default event loop is protected by this +module. If you I embedding this loop in the default loop, this is not +necessary, as C automatically does the right thing on fork. + +=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 + +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 @@ -84,28 +172,90 @@ =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 +=item $time = $loop->now + 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 +is the time that (relative) timers are based on, and referring to it is usually faster then calling EV::time. -=item $method = EV::method +=item EV::now_update + +=item $loop->now_update + +Establishes the current time by querying the kernel, updating the time +returned by C in the progress. This is a costly operation and +is usually done automatically within C. + +This function is rarely useful, but when some event callback runs for a +very long time without entering the event loop, updating libev's idea of +the current time is a good idea. + +=item EV::suspend -Returns an integer describing the backend used by libev (EV::METHOD_SELECT -or EV::METHOD_EPOLL). +=item $loop->suspend + +=item EV::resume + +=item $loop->resume + +These two functions suspend and resume a loop, for use when the loop is +not used for a while and timeouts should not be processed. + +A typical use case would be an interactive program such as a game: When +the user presses C<^Z> to suspend the game and resumes it an hour later it +would be best to handle timeouts as if no time had actually passed while +the program was suspended. This can be achieved by calling C +in your C handler, sending yourself a C and calling +C directly afterwards to resume timer processing. + +Effectively, all C watchers will be delayed by the time spend +between C and C, and all C watchers +will be rescheduled (that is, they will lose any events that would have +occured while suspended). + +After calling C you B call I function on the given +loop other than C, and you B call C +without a previous call to C. + +Calling C/C has the side effect of updating the event +loop time (see C). + +=item $backend = EV::backend + +=item $backend = $loop->backend + +Returns an integer describing the backend used by libev (EV::BACKEND_SELECT +or EV::BACKEND_EPOLL). =item EV::loop [$flags] +=item $loop->loop ([$flags]) + Begin checking for events and calling callbacks. It returns when a callback calls EV::unloop. @@ -117,14 +267,25 @@ =item EV::unloop [$how] +=item $loop->unloop ([$how]) + When called with no arguments or an argument of EV::UNLOOP_ONE, makes the innermost call to EV::loop return. 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. Sometimes 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. @@ -139,25 +300,64 @@ 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). +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 +(locally installed as F) for a more detailed discussion. + +=item $count = EV::pending_count + +=item $count = $loop->pending_count + +Returns the number of currently pending watchers. + +=item EV::invoke_pending + +=item $loop->invoke_pending + +Invoke all currently pending watchers. + =back -=head2 WATCHER + +=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 not be readable without blocking!\n" - }; + 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 @@ -166,10 +366,9 @@ 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). +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). 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 @@ -183,14 +382,9 @@ ->fh and so on) automatically stop and start it again if it is active, which means pending events get lost. -=head2 WATCHER TYPES +=head2 COMMON WATCHER METHODS -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). +This section lists methods common to all watchers. =over 4 @@ -204,7 +398,7 @@ 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. +regardless of whether the watcher was active or not. =item $bool = $w->is_active @@ -244,19 +438,30 @@ Note that the priority semantics have not yet been fleshed out and are subject to almost certain change. -=item $w->trigger ($revents) +=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), +convenient 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 +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 @@ -266,22 +471,41 @@ 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 +The initial value for keepalive is true (enabled), and you can change it any time. -Example: Register an IO watcher for some UDP socket but do not keep the +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 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: @@ -307,14 +531,24 @@ 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. +=item $w = $loop->timer ($after, $repeat, $callback) + +=item $w = $loop->timer_ns ($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 $after) after the callback returns. This means that the callback would be called roughly after C<$after> seconds, and then every C<$repeat> seconds. The timer does his best not @@ -330,7 +564,7 @@ =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 $w->again @@ -351,11 +585,21 @@ C<$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, $callback) + Similar to EV::timer, but is not based on relative timeouts but on absolute times. Apart from creating "simple" timers that trigger "at" the specified time, it can also be used for non-drifting absolute timers and @@ -374,7 +618,7 @@ at January 1st 2011 then it will run when the system time reaches or surpasses this time. -=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) +=item * repeating interval timer ($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, @@ -402,13 +646,14 @@ time as second argument. I. If you need to stop it, return 1e30 and stop it -afterwards. +watcher, ever, and MUST NOT call any event loop functions or methods>. 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 to the second argument). It -will usually be called just before the callback will be triggered, but -might be called at other times, too. +(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 @@ -432,25 +677,43 @@ =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. +=item $time = $w->at + +Return the time that the watcher is expected to trigger next. + +=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). +=item $w = $loop->signal ($signal, $callback) + +=item $w = $loop->signal_ns ($signal, $callback) + +Call the callback when $signal is received (the signal can be specified by +number or by name, just as with C or C<%SIG>). + +Only one event loop can grab a given signal - attempting to grab the same +signal from two EV loops will crash the program immediately or cause data +corruption. 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. @@ -458,8 +721,8 @@ =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 @@ -468,32 +731,48 @@ 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 $pid, $trace, $callback -=item $w = EV::child_ns $pid, $callback +=item $w = EV::child_ns $pid, $trace, $callback + +=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<$pid> is 0) has been received. More precisely: when the process -receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all +if C<$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. -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 have as many pid watchers per pid as you want. +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) +=item $w->set ($pid, $trace) -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 -=item $old_pid = $w->pid ($new_pid) - Returns the previously set process id and optionally set a new one. =item $exit_status = $w->rstatus @@ -506,24 +785,139 @@ 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 -Call the callback when there are no pending io, timer/periodic, signal or -child events, i.e. when the process is idle. +=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 + + +=head3 PREPARE WATCHERS - customise your event loop! + +=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. @@ -531,11 +925,21 @@ 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. @@ -554,7 +958,7 @@ # make the dispatcher handle any outstanding stuff ... not shown - # create an IO watcher for each and every socket + # create an I/O watcher for each and every socket @snmp_watcher = ( (map { EV::io $_, EV::READ, sub { } } keys %{ $dispatcher->{_descriptors} }), @@ -579,18 +983,132 @@ }; The callbacks of the created watchers will not be called as the watchers -are destroyed before this cna happen (remember EV::check gets called +are destroyed before this can 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. +=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 + +=item $w = $loop->fork ($callback) + +=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 + + +=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 +(locally installed as F) 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> is optional: if it is missing, then the +embedded event loop will be managed automatically (which is recommended), +otherwise you have to invoke C yourself. + +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 running in parallel 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 + +=item $w = EV::async $callback + +=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 ITHREADS + +Ithreads are not supported by this module in any way. Perl pseudo-threads +is evil stuff and must die. Real threads as provided by Coro are fully +supported (and enhanced support is available via L). =head1 FORK @@ -616,18 +1134,21 @@ }; default_loop - or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; + or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?'; 1; =head1 SEE ALSO - 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