--- cvsroot/EV/README 2007/12/08 14:44:21 1.17 +++ cvsroot/EV/README 2008/05/18 10:45:36 1.25 @@ -4,39 +4,39 @@ SYNOPSIS use EV; - - # TIMERS - - my $w = EV::timer 2, 0, sub { + + # TIMERS + + my $w = EV::timer 2, 0, sub { warn "is called after 2s"; }; - - my $w = EV::timer 2, 2, sub { + + 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 { + + 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 { + + # 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 { + + # 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 $w = EV::child 666, 0, sub { my ($w, $revents) = @_; my $status = $w->rstatus; }; @@ -46,8 +46,8 @@ my ($w, $revents) = @_; warn $w->path, " has changed somehow.\n"; }; - - # MAINLOOP + + # 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 @@ -56,32 +56,89 @@ This module provides an interface to libev (). While the documentation below is comprehensive, one might also consult the documentation of - libev itself () for more subtle - details on watcher semantics or some discussion on the available - backends, or how to force a specific backend with "LIBEV_FLAGS", or just - about in any case because it has much more detailed information. + libev itself () + for more subtle details on watcher semantics or some discussion on the + available backends, or how to force a specific backend with + "LIBEV_FLAGS", 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 AnyEvent 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. + +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. + + $loop = new EV::loop [$flags] + Create a new event loop as per the specified flags. Please refer to + the "ev_loop_new ()" function description in the libev documentation + () 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 "EV::FLAG_FORKCHECK" is recommended, as only the default event + loop is protected by this module. + + $loop->loop_fork + Must be called after a fork in the child, before entering or + continuing the event loop. An alternative is to use + "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at + some performance loss (refer to the libev documentation). + + $loop = EV::default_loop [$flags] + Return the default loop (which is a singleton object). BASIC INTERFACE $EV::DIED Must contain a reference to a function that is called when a - callback throws an exception (with $@ containing thr error). The + callback 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. + $flags = EV::supported_backends + $flags = EV::recommended_backends + $flags = EV::embeddable_backends + Returns the set (see "EV::BACKEND_*" 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). + + EV::sleep $seconds + Block the process for the given number of (fractional) seconds. + $time = EV::time Returns the current time in (fractional) seconds since the epoch. $time = EV::now + $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 usually faster then calling EV::time. - $method = EV::method + $backend = EV::backend + $backend = $loop->backend Returns an integer describing the backend used by libev (EV::METHOD_SELECT or EV::METHOD_EPOLL). EV::loop [$flags] + $loop->loop ([$flags]) Begin checking for events and calling callbacks. It returns when a callback calls EV::unloop. @@ -92,6 +149,7 @@ EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) EV::unloop [$how] + $loop->unloop ([$how]) When called with no arguments or an argument of EV::UNLOOP_ONE, makes the innermost call to EV::loop return. @@ -99,10 +157,12 @@ EV::loop will return as fast as possible. $count = EV::loop_count + $count = $loop->loop_count Return the number of times the event loop has polled for new events. Sometiems useful as a generation counter. EV::once $fh_or_undef, $events, $timeout, $cb->($revents) + $loop->once ($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. @@ -117,7 +177,7 @@ 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 "EV:ERROR", + general you can expect it to be a combination of "EV::ERROR", "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). EV::once doesn't return anything: the watchers stay active till @@ -125,6 +185,7 @@ the callback invoked. EV::feed_fd_event ($fd, $revents) + $loop->feed_fd_event ($fd, $revents) Feed an event on a file descriptor into EV. EV will react to this call as if the readyness notifications specified by $revents (a combination of "EV::READ" and "EV::WRITE") happened on the file @@ -134,14 +195,24 @@ Feed a signal event into EV. EV will react to this call as if the signal specified by $signal had occured. - WATCHER OBJECTS + EV::set_io_collect_interval $time + $loop->set_io_collect_interval ($time) + EV::set_timeout_collect_interval $time + $loop->set_timeout_collect_interval ($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 + for a more detailed discussion. + +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" + warn "yeah, STDIN should now be readable without blocking!\n" }; All watchers can be active (waiting for events) or inactive (paused). @@ -222,10 +293,9 @@ as if the watcher had received the given $revents mask. $revents = $w->clear_pending - If the watcher is pending, this function returns clears its pending - status and returns its $revents bitset (as if its callback was - invoked). If the watcher isn't pending it does nothing and returns - 0. + If the watcher is pending, this function clears its pending status + and returns its $revents bitset (as if its callback was invoked). If + the watcher isn't pending it does nothing and returns 0. $previous_state = $w->keepalive ($bool) Normally, "EV::loop" will return when there are no active watchers @@ -235,7 +305,7 @@ 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 + Sometimes, however, this gets in your way, for example when the module that calls "EV::loop" (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 @@ -255,14 +325,19 @@ my $udp_socket = ... my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; - $udp_watcher->keepalive (0); + $1000udp_watcher->keepalive (0); - WATCHER TYPES + $loop = $w->loop + Return the loop that this watcher is attached to. + +WATCHER TYPES Each of the following subsections describes a single watcher type. I/O WATCHERS - is this file descriptor readable or writable? $w = EV::io $fileno_or_fh, $eventmask, $callback $w = EV::io_ns $fileno_or_fh, $eventmask, $callback + $w = $loop->io ($fileno_or_fh, $eventmask, $callback) + $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback) As long as the returned watcher object is alive, call the $callback when at least one of events specified in $eventmask occurs. @@ -289,6 +364,8 @@ TIMER WATCHERS - relative and optionally repeating timeouts $w = EV::timer $after, $repeat, $callback $w = EV::timer_ns $after, $repeat, $callback + $w = $loop->timer ($after, $repeat, $callback) + $w = $loop->timer_ns ($after, $repeat, $callback) Calls the callback after $after seconds (which may be fractional). If $repeat is non-zero, the timer will be restarted (with the $repeat value as $after) after the callback returns. @@ -334,6 +411,8 @@ PERIODIC WATCHERS - to cron or not to cron? $w = EV::periodic $at, $interval, $reschedule_cb, $callback $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback + $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback) + $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback) Similar to EV::timer, but is not based on relative timeouts but on absolute times. Apart from creating "simple" timers that trigger "at" the specified time, it can also be used for non-drifting @@ -344,13 +423,15 @@ It has three distinct "modes": - * absolute timer ($interval = $reschedule_cb = 0) + * absolute timer ($interval = $reschedule_cb = 0) + This time simply fires at the wallclock time $at and doesn't repeat. It will not adjust when a time jump occurs, that is, if it is to be run at January 1st 2011 then it will run when the system time reaches or surpasses this time. - * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) + * repeating interval timer ($interval > 0, $reschedule_cb = 0) + In this mode the watcher will always be scheduled to time out at the next "$at + N * $interval" time (for some integer N) and then repeat, regardless of any time jumps. @@ -369,7 +450,8 @@ at the next possible time where "$time = $at (mod $interval)", regardless of any time jumps. - * manual reschedule mode ($reschedule_cb = coderef) + * 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 @@ -411,6 +493,9 @@ $w->again Simply stops and starts the watcher again. + $time = $w->at + Return the time that the watcher is expected to trigger next. + SIGNAL WATCHERS - signal me when a signal gets signalled! $w = EV::signal $signal, $callback $w = EV::signal_ns $signal, $callback @@ -437,12 +522,17 @@ optionally set a new one. CHILD WATCHERS - watch out for process status changes - $w = EV::child $pid, $callback - $w = EV::child_ns $pid, $callback + $w = EV::child $pid, $trace, $callback + $w = EV::child_ns $pid, $trace, $callback + $w = $loop->child ($pid, $trace, $callback) + $w = $loop->child_ns ($pid, $trace, $callback) Call the callback when a status change for pid $pid (or any pid if - $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. + $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 "SIGCHLD", 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 @@ -459,12 +549,11 @@ The "child_ns" variant doesn't start (activate) the newly created watcher. - $w->set ($pid) + $w->set ($pid, $trace) Reconfigures the watcher, see the constructor above for details. Can be called at any time. $current_pid = $w->pid - $old_pid = $w->pid ($new_pid) Returns the previously set process id and optionally set a new one. $exit_status = $w->rstatus @@ -478,6 +567,8 @@ STAT WATCHERS - did the file attributes just change? $w = EV::stat $path, $interval, $callback $w = EV::stat_ns $path, $interval, $callback + $w = $loop->stat ($path, $interval, $callback) + $w = $loop->stat_ns ($path, $interval, $callback) Call the callback when a file status change has been detected on $path. The $path does not need to exist, changing from "path exists" to "path does not exist" is a status change like any other. @@ -547,6 +638,8 @@ IDLE WATCHERS - when you've got nothing better to do... $w = EV::idle $callback $w = EV::idle_ns $callback + $w = $loop->idle ($callback) + $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 @@ -572,6 +665,8 @@ PREPARE WATCHERS - customise your event loop! $w = EV::prepare $callback $w = EV::prepare_ns $callback + $w = $loop->prepare ($callback) + $w = $loop->prepare_ns ($callback) Call the callback just before the process would block. You can still create/modify any watchers at this point. @@ -583,6 +678,8 @@ CHECK WATCHERS - customise your event loop even more! $w = EV::check $callback $w = EV::check_ns $callback + $w = $loop->check ($callback) + $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. @@ -641,12 +738,67 @@ $w = EV::fork $callback $w = EV::fork_ns $callback + $w = $loop->fork ($callback) + $w = $loop->fork_ns ($callback) Call the callback before the event loop is resumed in the child process after a fork. The "fork_ns" variant doesn't start (activate) the newly created watcher. + 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 + 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; + + $w = EV::embed $otherloop, $callback + $w = EV::embed_ns $otherloop, $callback + $w = $loop->embed ($otherloop, $callback) + $w = $loop->embed_ns ($otherloop, $callback) + Call the callback when the embedded event loop ($otherloop) has any + I/O activity. The $callback should alwas be specified as "undef" in + this version of EV, which means the embedded event loop will be + managed automatically. + + The "embed_ns" variant doesn't start (activate) the newly created + watcher. + + 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. + + $w = EV::async $callback + $w = EV::async_ns $callback + $w->send + $bool = $w->async_pending + PERL SIGNALS While Perl signal handling (%SIG) is not affected by EV, the behaviour with EV is as the same as any other C library: Perl-signals will only be @@ -662,8 +814,8 @@ my $async_check = EV::check sub { }; - This ensures that perl shortly gets into control for a short time, and - also ensures slower overall operation. + This ensures that perl gets into control for a short time to handle any + pending signals, and also ensures (slightly) slower overall operation. THREADS Threads are not supported by this module in any way. Perl pseudo-threads @@ -688,8 +840,10 @@ course. SEE ALSO - EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event - loop), Coro::EV (efficient coroutines with EV). + EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event + loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines + with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop + agnostic and portable event driven programming. AUTHOR Marc Lehmann