--- AnyEvent/lib/AnyEvent.pm 2005/12/30 01:28:31 1.7 +++ AnyEvent/lib/AnyEvent.pm 2008/04/16 14:04:45 1.50 @@ -2,51 +2,73 @@ AnyEvent - provide framework for multiple event loops -Event, Coro, Glib, Tk - various supported event loops +EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl - various supported event loops =head1 SYNOPSIS use AnyEvent; - my $w = AnyEvent->io (fh => ..., poll => "[rw]+", cb => sub { - my ($poll_got) = @_; + my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... }); -* only one io watcher per $fh and $poll type is allowed (i.e. on a socket -you can have one r + one w or one rw watcher, not any more (limitation by -Tk). - -* the C<$poll_got> passed to the handler needs to be checked by looking -for single characters (e.g. with a regex), as it can contain more event -types than were requested (e.g. a 'w' watcher might generate 'rw' events, -limitation by Glib). - -* AnyEvent will keep filehandles alive, so as long as the watcher exists, -the filehandle exists. - my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); -* io and time watchers get canceled whenever $w is destroyed, so keep a copy + my $w = AnyEvent->condvar; # stores wether a condition was flagged + $w->wait; # enters "main loop" till $condvar gets ->broadcast + $w->broadcast; # wake up current and all future wait's -* timers can only be used once and must be recreated for repeated -operation (limitation by Glib and Tk). +=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) - my $w = AnyEvent->condvar; # kind of main loop replacement - $w->wait; # enters main loop till $condvar gets ->broadcast - $w->broadcast; # wake up current and all future wait's +Glib, POE, IO::Async, Event... CPAN offers event models by the dozen +nowadays. So what is different about AnyEvent? + +Executive Summary: AnyEvent is I, AnyEvent is I and AnyEvent is I. + +First and foremost, I itself, it only +interfaces to whatever event model the main program happens to use in a +pragmatic way. For event models and certain classes of immortals alike, +the statement "there can only be one" is a bitter reality, and AnyEvent +helps hiding the differences. + +The goal of AnyEvent is to offer module authors the ability to do event +programming (waiting for I/O or timer events) without subscribing to a +religion, a way of living, and most importantly: without forcing your +module users into the same thing by forcing them to use the same event +model you use. + +For modules like POE or IO::Async (which is actually doing all I/O +I...), using them in your module is like joining a +cult: After you joined, you are dependent on them and you cannot use +anything else, as it is simply incompatible to everything that isn't +itself. + +AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk +works fine etc. etc. but none of these work together with the rest: POE ++ IO::Async? no go. Tk + Event? no go. If your module uses one of +those, every user of your module has to use it, too. If your module +uses AnyEvent, it works transparently with all event models it supports +(including stuff like POE and IO::Async). + +In addition of being free of having to use I, AnyEvent also is free of bloat and policy: with POE or similar +modules, you get an enourmous amount of code and strict rules you have +to follow. AnyEvent, on the other hand, is lean and to the point by only +offering the functionality that is useful, in as thin as a wrapper as +technically possible. + +Of course, if you want lots of policy (this can arguably be somewhat +useful) and you want to force your users to use the one and only event +model, you should I use this module. -* condvars are used to give blocking behaviour when neccessary. Create -a condvar for any "request" or "event" your module might create, C<< -->broadcast >> it when the event happens and provide a function that calls -C<< ->wait >> for it. See the examples below. =head1 DESCRIPTION L provides an identical interface to multiple event loops. This -allows module authors to utilizy an event loop without forcing module +allows module authors to utilise an event loop without forcing module users to use the same event loop (as only a single event loop can coexist peacefully at any one time). @@ -55,22 +77,239 @@ On the first call of any method, the module tries to detect the currently loaded event loop by probing wether any of the following modules is -loaded: L, L, L, L. The first one found is -used. If none is found, the module tries to load these modules in the -order given. The first one that could be successfully loaded will be -used. If still none could be found, it will issue an error. +loaded: L, L, L, L, L, L. The +first one found is used. If none are found, the module tries to load these +modules in the order given. The first one that could be successfully +loaded will be used. If still none could be found, AnyEvent will fall back +to a pure-perl event loop, which is also not very efficient. + +Because AnyEvent first checks for modules that are already loaded, loading +an Event model explicitly before first using AnyEvent will likely make +that model the default. For example: + + use Tk; + use AnyEvent; + + # .. AnyEvent will likely default to Tk + +The pure-perl implementation of AnyEvent is called +C. Like other event modules you can load it +explicitly. + +=head1 WATCHERS + +AnyEvent has the central concept of a I, which is an object that +stores relevant data for each kind of event you are waiting for, such as +the callback to call, the filehandle to watch, etc. + +These watchers are normal Perl objects with normal Perl lifetime. After +creating a watcher it will immediately "watch" for events and invoke +the callback. To disable the watcher you have to destroy it (e.g. by +setting the variable that stores it to C or otherwise deleting all +references to it). + +All watchers are created by calling a method on the C class. + +=head2 IO WATCHERS + +You can create I/O watcher by calling the C<< AnyEvent->io >> method with +the following mandatory arguments: + +C the Perl I (not filedescriptor) to watch for +events. C must be a string that is either C or C, that creates +a watcher waiting for "r"eadable or "w"ritable events. C the callback +to invoke everytime the filehandle becomes ready. + +Filehandles will be kept alive, so as long as the watcher exists, the +filehandle exists, too. + +Example: + + # wait for readability of STDIN, then read a line and disable the watcher + my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { + chomp (my $input = ); + warn "read: $input\n"; + undef $w; + }); + +=head2 TIME WATCHERS + +You can create a time watcher by calling the C<< AnyEvent->timer >> +method with the following mandatory arguments: + +C after how many seconds (fractions are supported) should the timer +activate. C the callback to invoke. + +The timer callback will be invoked at most once: if you want a repeating +timer you have to create a new watcher (this is a limitation by both Tk +and Glib). + +Example: + + # fire an event after 7.7 seconds + my $w = AnyEvent->timer (after => 7.7, cb => sub { + warn "timeout\n"; + }); + + # to cancel the timer: + undef $w; + +=head2 CONDITION WATCHERS + +Condition watchers can be created by calling the C<< AnyEvent->condvar >> +method without any arguments. + +A condition watcher watches for a condition - precisely that the C<< +->broadcast >> method has been called. + +Note that condition watchers recurse into the event loop - if you have +two watchers that call C<< ->wait >> in a round-robbin fashion, you +lose. Therefore, condition watchers are good to export to your caller, but +you should avoid making a blocking wait, at least in callbacks, as this +usually asks for trouble. + +The watcher has only two methods: + +=over 4 + +=item $cv->wait + +Wait (blocking if necessary) until the C<< ->broadcast >> method has been +called on c<$cv>, while servicing other watchers normally. + +You can only wait once on a condition - additional calls will return +immediately. + +Not all event models support a blocking wait - some die in that case +(programs might want to do that so they stay interactive), so I, but let the +caller decide wether the call will block or not (for example, by coupling +condition variables with some kind of request results and supporting +callbacks so the caller knows that getting the result will not block, +while still suppporting blocking waits if the caller so desires). + +Another reason I to C<< ->wait >> in a module is that you cannot +sensibly have two C<< ->wait >>'s in parallel, as that would require +multiple interpreters or coroutines/threads, none of which C +can supply (the coroutine-aware backends C and C +explicitly support concurrent C<< ->wait >>'s from different coroutines, +however). + +=item $cv->broadcast + +Flag the condition as ready - a running C<< ->wait >> and all further +calls to C will return after this method has been called. If nobody +is waiting the broadcast will be remembered.. + +Example: + + # wait till the result is ready + my $result_ready = AnyEvent->condvar; + + # do something such as adding a timer + # or socket watcher the calls $result_ready->broadcast + # when the "result" is ready. + + $result_ready->wait; + +=back + +=head2 SIGNAL WATCHERS + +You can listen for signals using a signal watcher, C is the signal +I without any C prefix. Multiple signals events can be clumped +together into one callback invocation, and callback invocation might or +might not be asynchronous. + +These watchers might use C<%SIG>, so programs overwriting those signals +directly will likely not work correctly. + +Example: exit on SIGINT + + my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); + +=head2 CHILD PROCESS WATCHERS + +You can also listen for the status of a child process specified by the +C argument (or any child if the pid argument is 0). The watcher will +trigger as often as status change for the child are received. This works +by installing a signal handler for C. The callback will be called with +the pid and exit status (as returned by waitpid). + +Example: wait for pid 1333 + + my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); + +=head1 GLOBALS =over 4 +=item $AnyEvent::MODEL + +Contains C until the first watcher is being created. Then it +contains the event model that is being used, which is the name of the +Perl class implementing the model. This class is usually one of the +C modules, but can be any other class in the case +AnyEvent has been extended at runtime (e.g. in I). + +The known classes so far are: + + AnyEvent::Impl::CoroEV based on Coro::EV, best choice. + AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. + AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). + AnyEvent::Impl::Event based on Event, also second best choice :) + AnyEvent::Impl::Glib based on Glib, third-best choice. + AnyEvent::Impl::Tk based on Tk, very bad choice. + AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. + +=item AnyEvent::detect + +Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if +necessary. You should only call this function right before you would have +created an AnyEvent watcher anyway, that is, very late at runtime. + +=back + +=head1 WHAT TO DO IN A MODULE + +As a module author, you should "use AnyEvent" and call AnyEvent methods +freely, but you should not load a specific event module or rely on it. + +Be careful when you create watchers in the module body - Anyevent will +decide which event module to use as soon as the first method is called, so +by calling AnyEvent in your module body you force the user of your module +to load the event module first. + +=head1 WHAT TO DO IN THE MAIN PROGRAM + +There will always be a single main program - the only place that should +dictate which event model to use. + +If it doesn't care, it can just "use AnyEvent" and use it itself, or not +do anything special and let AnyEvent decide which implementation to chose. + +If the main program relies on a specific event model (for example, in Gtk2 +programs you have to rely on either Glib or Glib::Event), you should load +it before loading AnyEvent or any module that uses it, generally, as early +as possible. The reason is that modules might create watchers when they +are loaded, and AnyEvent will decide on the event model to use as soon as +it creates watchers, and it might chose the wrong one unless you load the +correct one yourself. + +You can chose to use a rather inefficient pure-perl implementation by +loading the C module, but letting AnyEvent chose is +generally better. + =cut package AnyEvent; no warnings; -use strict 'vars'; +use strict; + use Carp; -our $VERSION = '0.4'; +our $VERSION = '3.0'; our $MODEL; our $AUTOLOAD; @@ -78,54 +317,203 @@ our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; +our @REGISTRY; + my @models = ( - [Coro => Coro::Event::], - [Event => Event::], - [Glib => Glib::], - [Tk => Tk::], + [Coro::EV:: => AnyEvent::Impl::CoroEV::], + [Coro::Event:: => AnyEvent::Impl::CoroEvent::], + [EV:: => AnyEvent::Impl::EV::], + [Event:: => AnyEvent::Impl::Event::], + [Glib:: => AnyEvent::Impl::Glib::], + [Tk:: => AnyEvent::Impl::Tk::], + [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], ); -our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY); - -sub AUTOLOAD { - $AUTOLOAD =~ s/.*://; - - $method{$AUTOLOAD} - or croak "$AUTOLOAD: not a valid method for AnyEvent objects"; +our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); +sub detect() { unless ($MODEL) { + no strict 'refs'; + # check for already loaded models - for (@models) { - my ($model, $package) = @$_; + for (@REGISTRY, @models) { + my ($package, $model) = @$_; if (${"$package\::VERSION"} > 0) { - eval "require AnyEvent::Impl::$model"; - warn "AnyEvent: found model '$model', using it.\n" if $MODEL && $verbose > 1; - last if $MODEL; + if (eval "require $model") { + $MODEL = $model; + warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; + last; + } } } unless ($MODEL) { # try to load a model - for (@models) { - my ($model, $package) = @$_; - eval "require AnyEvent::Impl::$model"; - warn "AnyEvent: autprobed and loaded model '$model', using it.\n" if $MODEL && $verbose > 1; - last if $MODEL; + for (@REGISTRY, @models) { + my ($package, $model) = @$_; + if (eval "require $package" + and ${"$package\::VERSION"} > 0 + and eval "require $model") { + $MODEL = $model; + warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; + last; + } } $MODEL - or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk."; + or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event), Glib or Tk."; } + + unshift @ISA, $MODEL; + push @{"$MODEL\::ISA"}, "AnyEvent::Base"; } - @ISA = $MODEL; + $MODEL +} + +sub AUTOLOAD { + (my $func = $AUTOLOAD) =~ s/.*://; + + $method{$func} + or croak "$func: not a valid method for AnyEvent objects"; + + detect unless $MODEL; my $class = shift; - $class->$AUTOLOAD (@_); + $class->$func (@_); } -=back +package AnyEvent::Base; + +# default implementation for ->condvar, ->wait, ->broadcast + +sub condvar { + bless \my $flag, "AnyEvent::Base::CondVar" +} + +sub AnyEvent::Base::CondVar::broadcast { + ${$_[0]}++; +} + +sub AnyEvent::Base::CondVar::wait { + AnyEvent->one_event while !${$_[0]}; +} + +# default implementation for ->signal + +our %SIG_CB; + +sub signal { + my (undef, %arg) = @_; + + my $signal = uc $arg{signal} + or Carp::croak "required option 'signal' is missing"; + + $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; + $SIG{$signal} ||= sub { + $_->() for values %{ $SIG_CB{$signal} || {} }; + }; + + bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" +} + +sub AnyEvent::Base::Signal::DESTROY { + my ($signal, $cb) = @{$_[0]}; + + delete $SIG_CB{$signal}{$cb}; + + $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; +} + +# default implementation for ->child + +our %PID_CB; +our $CHLD_W; +our $CHLD_DELAY_W; +our $PID_IDLE; +our $WNOHANG; + +sub _child_wait { + while (0 < (my $pid = waitpid -1, $WNOHANG)) { + $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), + (values %{ $PID_CB{0} || {} }); + } + + undef $PID_IDLE; +} + +sub _sigchld { + # make sure we deliver these changes "synchronous" with the event loop. + $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { + undef $CHLD_DELAY_W; + &_child_wait; + }); +} + +sub child { + my (undef, %arg) = @_; + + defined (my $pid = $arg{pid} + 0) + or Carp::croak "required option 'pid' is missing"; + + $PID_CB{$pid}{$arg{cb}} = $arg{cb}; + + unless ($WNOHANG) { + $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; + } + + unless ($CHLD_W) { + $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); + # child could be a zombie already, so make at least one round + &_sigchld; + } + + bless [$pid, $arg{cb}], "AnyEvent::Base::Child" +} + +sub AnyEvent::Base::Child::DESTROY { + my ($pid, $cb) = @{$_[0]}; + + delete $PID_CB{$pid}{$cb}; + delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; + + undef $CHLD_W unless keys %PID_CB; +} + +=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE + +If you need to support another event library which isn't directly +supported by AnyEvent, you can supply your own interface to it by +pushing, before the first watcher gets created, the package name of +the event module and the package name of the interface to use onto +C<@AnyEvent::REGISTRY>. You can do that before and even without loading +AnyEvent. + +Example: + + push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; + +This tells AnyEvent to (literally) use the C +package/class when it finds the C package/module is loaded. When +AnyEvent is loaded and asked to find a suitable event model, it will +first check for the presence of urxvt. + +The class should provide implementations for all watcher types (see +L (source code), L +(Source code) and so on for actual examples, use C to see the sources). + +The above isn't fictitious, the I (a.k.a. urxvt) +uses the above line as-is. An interface isn't included in AnyEvent +because it doesn't make sense outside the embedded interpreter inside +I, and it is updated and maintained as part of the +I distribution. + +I also cheats a bit by not providing blocking access to +condition variables: code blocking while waiting for a condition will +C. This still works with most modules/usages, and blocking calls must +not be in an interactive application, so it makes sense. =head1 ENVIRONMENT VARIABLES @@ -252,7 +640,7 @@ my $data = $fcp->client_get ($url); -2. Blocking, but parallelizing: +2. Blocking, but running in parallel: my @datas = map $_->result, map $fcp->txn_client_get ($_), @@ -261,9 +649,9 @@ Both blocking examples work without the module user having to know anything about events. -3a. Event-based in a main program, using any support Event module: +3a. Event-based in a main program, using any supported event module: - use Event; + use EV; $fcp->txn_client_get ($url)->cb (sub { my $txn = shift; @@ -271,7 +659,7 @@ ... }); - Event::loop; + EV::loop; 3b. The module user could use AnyEvent, too: @@ -288,11 +676,14 @@ =head1 SEE ALSO -Event modules: L, L, L, L, L. +Event modules: L, L, L, L, +L, L, L, L, L, L. -Implementations: L, L, L, L. +Implementations: L, L, +L, L, +L, L, L. -Nontrivial usage example: L. +Nontrivial usage examples: L, L. =head1