--- AnyEvent/lib/AnyEvent.pm 2008/07/09 11:53:40 1.170 +++ AnyEvent/lib/AnyEvent.pm 2010/12/29 04:16:33 1.342 @@ -1,24 +1,44 @@ =head1 NAME -AnyEvent - provide framework for multiple event loops +AnyEvent - the DBI of event loop programming -EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops +EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt +and POE are various supported event loops/environments. =head1 SYNOPSIS use AnyEvent; - my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { - ... - }); + # if you prefer function calls, look at the AE manpage for + # an alternative API. + + # file handle or descriptor readable + my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); + + # one-shot or repeating timers + my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); + my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...); + + print AnyEvent->now; # prints current event loop time + print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. + + # POSIX signal + my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); - my $w = AnyEvent->timer (after => $seconds, cb => sub { + # child process exit + my $w = AnyEvent->child (pid => $pid, cb => sub { + my ($pid, $status) = @_; ... }); + # called when event loop idle (if applicable) + my $w = AnyEvent->idle (cb => sub { ... }); + my $w = AnyEvent->condvar; # stores whether a condition was flagged $w->send; # wake up current and all future recv's $w->recv; # enters "main loop" till $condvar gets ->send + # use a condvar in callback mode: + $w->cb (sub { $_[0]->recv }); =head1 INTRODUCTION/TUTORIAL @@ -26,6 +46,16 @@ in a tutorial or some gentle introduction, have a look at the L manpage. +=head1 SUPPORT + +An FAQ document is available as L. + +There also is a mailinglist for discussing all things AnyEvent, and an IRC +channel, too. + +See the AnyEvent project page at the B, at L, for more info. + =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) Glib, POE, IO::Async, Event... CPAN offers event models by the dozen @@ -50,7 +80,7 @@ For modules like POE or IO::Async (which is a total misnomer as it 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 +like joining a cult: After you join, you are dependent on them and you cannot use anything else, as they are simply incompatible to everything that isn't them. What's worse, all the potential users of your module are I forced to use the same event loop you use. @@ -61,13 +91,13 @@ your module uses one of those, every user of your module has to use it, too. But if your module uses AnyEvent, it works transparently with all event models it supports (including stuff like IO::Async, as long as those -use one of the supported event loops. It is trivial to add new event loops +use one of the supported event loops. It is easy to add new event loops to AnyEvent, too, so it is future-proof). In addition to being free of having to use I, AnyEvent also is free of bloat and policy: with POE or similar modules, you get an enormous amount of code and strict rules you have to -follow. AnyEvent, on the other hand, is lean and up to the point, by only +follow. AnyEvent, on the other hand, is lean and to the point, by only offering the functionality that is necessary, in as thin as a wrapper as technically possible. @@ -83,24 +113,22 @@ =head1 DESCRIPTION -L provides an identical interface to multiple event loops. This -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). +L provides a uniform interface to various event loops. This +allows module authors to use event loop functionality without forcing +module users to use a specific event loop implementation (since more +than one event loop cannot coexist peacefully). The interface itself is vaguely similar, but not identical to the L module. During the first call of any watcher-creation method, the module tries to detect the currently loaded event loop by probing whether one of the -following modules is already loaded: L, -L, L, L, L, L, L, -L. The first one found is used. If none are found, the module tries -to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl -adaptor should always succeed) in the order given. The first one that can -be successfully loaded will be used. If, after this, still none could be -found, AnyEvent will fall back to a pure-perl event loop, which is not -very efficient, but should work everywhere. +following modules is already loaded: L, L, +L, L, L, L, L, L. The first one +found is used. If none are detected, the module tries to load the first +four modules in the order given; but note that if L is not +available, the pure-perl L should always work, so +the other two are not normally tried. Because AnyEvent first checks for modules that are already loaded, loading an event model explicitly before first using AnyEvent will likely make @@ -112,8 +140,9 @@ # .. AnyEvent will likely default to Tk The I means that, if any module loads another event model and -starts using it, all bets are off. Maybe you should tell their authors to -use AnyEvent so their modules work together with others seamlessly... +starts using it, all bets are off - this case should be very rare though, +as very few modules hardcode event loops without announcing this very +loudly. The pure-perl implementation of AnyEvent is called C. Like other event modules you can load it @@ -130,7 +159,13 @@ callback when the event occurs (of course, only when the event model is in control). -To disable the watcher you have to destroy it (e.g. by setting the +Note that B +potentially in use by the event loop (such as C<$_> or C<$[>) and that B<< +callbacks must not C >>. The former is good programming practice in +Perl and the latter stems from the fact that exception handling differs +widely between event loops. + +To disable a watcher you have to destroy it (e.g. by setting the variable you store it in to C or otherwise deleting all references to it). @@ -139,7 +174,7 @@ Many watchers either are used with "recursion" (repeating timers for example), or need to refer to their watcher object in other ways. -An any way to achieve that is this pattern: +One way to achieve that is this pattern: my $w; $w = AnyEvent->type (arg => value ..., cb => sub { # you can use $w here, for example to undef it @@ -152,14 +187,26 @@ =head2 I/O WATCHERS + $w = AnyEvent->io ( + fh => , + poll => <"r" or "w">, + cb => , + ); + You can create an I/O watcher by calling the C<< AnyEvent->io >> method with the following mandatory key-value pairs as arguments: -C the Perl I (I file descriptor) to watch for events -(AnyEvent might or might not keep a reference to this file handle). C -must be a string that is either C or C, which creates a watcher -waiting for "r"eadable or "w"ritable events, respectively. C is the -callback to invoke each time the file handle becomes ready. +C is the Perl I (or a naked file descriptor) to watch +for events (AnyEvent might or might not keep a reference to this file +handle). Note that only file handles pointing to things for which +non-blocking operation makes sense are allowed. This includes sockets, +most character devices, pipes, fifos and so on, but not for example files +or block devices. + +C must be a string that is either C or C, which creates a +watcher waiting for "r"eadable or "w"ritable events, respectively. + +C is the callback to invoke each time the file handle becomes ready. Although the callback might get passed parameters, their value and presence is undefined and you cannot rely on them. Portable AnyEvent @@ -169,7 +216,7 @@ You must not close a file handle as long as any watcher is active on the underlying file descriptor. -Some event loops issue spurious readyness notifications, so you should +Some event loops issue spurious readiness notifications, so you should always use non-blocking calls when reading/writing from/to your file handles. @@ -184,6 +231,14 @@ =head2 TIME WATCHERS + $w = AnyEvent->timer (after => , cb => ); + + $w = AnyEvent->timer ( + after => , + interval => , + cb => , + ); + You can create a time watcher by calling the C<< AnyEvent->timer >> method with the following mandatory arguments: @@ -195,14 +250,14 @@ presence is undefined and you cannot rely on them. Portable AnyEvent callbacks cannot use arguments passed to time watcher callbacks. -The callback will normally be invoked once only. If you specify another +The callback will normally be invoked only once. If you specify another parameter, C, as a strictly positive number (> 0), then the callback will be invoked regularly at that interval (in fractional seconds) after the first invocation. If C is specified with a -false value, then it is treated as if it were missing. +false value, then it is treated as if it were not specified at all. The callback will be rescheduled before invoking the callback, but no -attempt is done to avoid timer drift in most backends, so the interval is +attempt is made to avoid timer drift in most backends, so the interval is only approximate. Example: fire an event after 7.7 seconds. @@ -230,10 +285,10 @@ use absolute time internally. This makes a difference when your clock "jumps", for example, when ntp decides to set your clock backwards from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to -fire "after" a second might actually take six years to finally fire. +fire "after a second" might actually take six years to finally fire. AnyEvent cannot compensate for this. The only event loop that is conscious -about these issues is L, which offers both relative (ev_timer, based +of these issues is L, which offers both relative (ev_timer, based on true relative time) and absolute (ev_periodic, based on wallclock time) timers. @@ -265,15 +320,15 @@ This function is also often faster then C<< AnyEvent->time >>, and thus the preferred method if you want some timestamp (for example, -L uses this to update it's activity timeouts). +L uses this to update its activity timeouts). The rest of this section is only of relevance if you try to be very exact -with your timing, you can skip it without bad conscience. +with your timing; you can skip it without a bad conscience. For a practical example of when these times differ, consider L and L and the following set-up: -The event loop is running and has just invoked one of your callback at +The event loop is running and has just invoked one of your callbacks at time=500 (assume no other callbacks delay processing). In your callback, you wait a second by executing C (blocking the process for a second) and then (at time=501) you create a relative timer that fires @@ -301,10 +356,34 @@ difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into account. +=item AnyEvent->now_update + +Some event loops (such as L or L) cache +the current time for each loop iteration (see the discussion of L<< +AnyEvent->now >>, above). + +When a callback runs for a long time (or when the process sleeps), then +this "current" time will differ substantially from the real time, which +might affect timers and time-outs. + +When this is the case, you can call this method, which will update the +event loop's idea of "current time". + +A typical example would be a script in a web server (e.g. C) - +when mod_perl executes the script, then the event loop will have the wrong +idea about the "current time" (being potentially far in the past, when the +script ran the last time). In that case you should arrange a call to C<< +AnyEvent->now_update >> each time the web server process wakes up again +(e.g. at the start of your script, or in a handler). + +Note that updating the time I cause some events to be handled. + =back =head2 SIGNAL WATCHERS + $w = AnyEvent->signal (signal => , cb => ); + You can watch for signals using a signal watcher, C is the signal I in uppercase and without any C prefix, C is the Perl callback to be invoked whenever a signal occurs. @@ -319,37 +398,94 @@ but it is guaranteed not to interrupt any other callbacks. The main advantage of using these watchers is that you can share a signal -between multiple watchers. +between multiple watchers, and AnyEvent will ensure that signals will not +interrupt your program at bad times. -This watcher might use C<%SIG>, so programs overwriting those signals -directly will likely not work correctly. +This watcher might use C<%SIG> (depending on the event loop used), +so programs overwriting those signals directly will likely not work +correctly. Example: exit on SIGINT my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); +=head3 Restart Behaviour + +While restart behaviour is up to the event loop implementation, most will +not restart syscalls (that includes L and AnyEvent's +pure perl implementation). + +=head3 Safe/Unsafe Signals + +Perl signals can be either "safe" (synchronous to opcode handling) or +"unsafe" (asynchronous) - the former might get delayed indefinitely, the +latter might corrupt your memory. + +AnyEvent signal handlers are, in addition, synchronous to the event loop, +i.e. they will not interrupt your running perl program but will only be +called as part of the normal event handling (just like timer, I/O etc. +callbacks, too). + +=head3 Signal Races, Delays and Workarounds + +Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching +callbacks to signals in a generic way, which is a pity, as you cannot +do race-free signal handling in perl, requiring C libraries for +this. AnyEvent will try to do its best, which means in some cases, +signals will be delayed. The maximum time a signal might be delayed is +specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This +variable can be changed only before the first signal watcher is created, +and should be left alone otherwise. This variable determines how often +AnyEvent polls for signals (in case a wake-up was missed). Higher values +will cause fewer spurious wake-ups, which is better for power and CPU +saving. + +All these problems can be avoided by installing the optional +L module, which works with most event loops. It will not +work with inherently broken event loops such as L or L +(and not with L currently, as POE does its own workaround with +one-second latency). For those, you just have to suffer the delays. + =head2 CHILD PROCESS WATCHERS -You can also watch on a child process exit and catch its exit status. + $w = AnyEvent->child (pid => , cb => ); + +You can also watch for a child process exit and catch its exit status. -The child process is specified by the C argument (if set to C<0>, it -watches for any child process exit). 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), so unlike other watcher types, -you I rely on child watcher callback arguments. +The child process is specified by the C argument (on some backends, +using C<0> watches for any child process exit, on others this will +croak). The watcher will be triggered only when the child process has +finished and an exit status is available, not on any trace events +(stopped/continued). + +The callback will be called with the pid and exit status (as returned by +waitpid), so unlike other watcher types, you I rely on child watcher +callback arguments. + +This watcher type works by installing a signal handler for C, +and since it cannot be shared, nothing else should use SIGCHLD or reap +random child processes (waiting for specific child processes, e.g. inside +C, is just fine). There is a slight catch to child watchers, however: you usually start them I the child process was created, and this means the process could have exited already (and no SIGCHLD will be sent anymore). -Not all event models handle this correctly (POE doesn't), but even for -event models that I handle this correctly, they usually need to be -loaded before the process exits (i.e. before you fork in the first place). - -This means you cannot create a child watcher as the very first thing in an -AnyEvent program, you I to create at least one watcher before you -C the child (alternatively, you can call C). +Not all event models handle this correctly (neither POE nor IO::Async do, +see their AnyEvent::Impl manpages for details), but even for event models +that I handle this correctly, they usually need to be loaded before +the process exits (i.e. before you fork in the first place). AnyEvent's +pure perl event loop handles all cases correctly regardless of when you +start the watcher. + +This means you cannot create a child watcher as the very first +thing in an AnyEvent program, you I to create at least one +watcher before you C the child (alternatively, you can call +C). + +As most event loops do not support waiting for child events, they will be +emulated by AnyEvent in most cases, in which the latency and race problems +mentioned in the description of signal watchers apply. Example: fork a process and wait for it @@ -369,34 +505,99 @@ # do something else, then wait for process exit $done->recv; +=head2 IDLE WATCHERS + + $w = AnyEvent->idle (cb => ); + +This will repeatedly invoke the callback after the process becomes idle, +until either the watcher is destroyed or new events have been detected. + +Idle watchers are useful when there is a need to do something, but it +is not so important (or wise) to do it instantly. The callback will be +invoked only when there is "nothing better to do", which is usually +defined as "all outstanding events have been handled and no new events +have been detected". That means that idle watchers ideally get invoked +when the event loop has just polled for new events but none have been +detected. Instead of blocking to wait for more events, the idle watchers +will be invoked. + +Unfortunately, most event loops do not really support idle watchers (only +EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent +will simply call the callback "from time to time". + +Example: read lines from STDIN, but only process them when the +program is otherwise idle: + + my @lines; # read data + my $idle_w; + my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { + push @lines, scalar ; + + # start an idle watcher, if not already done + $idle_w ||= AnyEvent->idle (cb => sub { + # handle only one line, when there are lines left + if (my $line = shift @lines) { + print "handled when idle: $line"; + } else { + # otherwise disable the idle watcher again + undef $idle_w; + } + }); + }); + =head2 CONDITION VARIABLES + $cv = AnyEvent->condvar; + + $cv->send (); + my @res = $cv->recv; + If you are familiar with some event loops you will know that all of them require you to run some blocking "loop", "run" or similar function that will actively watch for new events and call your callbacks. -AnyEvent is different, it expects somebody else to run the event loop and -will only block when necessary (usually when told by the user). +AnyEvent is slightly different: it expects somebody else to run the event +loop and will only block when necessary (usually when told by the user). -The instrument to do that is called a "condition variable", so called -because they represent a condition that must become true. +The tool to do that is called a "condition variable", so called because +they represent a condition that must become true. + +Now is probably a good time to look at the examples further below. Condition variables can be created by calling the C<< AnyEvent->condvar >> method, usually without arguments. The only argument pair allowed is C, which specifies a callback to be called when the condition variable -becomes true. +becomes true, with the condition variable as the first argument (but not +the results). After creation, the condition variable is "false" until it becomes "true" by calling the C method (or calling the condition variable as if it were a callback, read about the caveats in the description for the C<< ->send >> method). -Condition variables are similar to callbacks, except that you can -optionally wait for them. They can also be called merge points - points -in time where multiple outstanding events have been processed. And yet -another way to call them is transactions - each condition variable can be -used to represent a transaction, which finishes at some point and delivers -a result. +Since condition variables are the most complex part of the AnyEvent API, here are +some different mental models of what they are - pick the ones you can connect to: + +=over 4 + +=item * Condition variables are like callbacks - you can call them (and pass them instead +of callbacks). Unlike callbacks however, you can also wait for them to be called. + +=item * Condition variables are signals - one side can emit or send them, +the other side can wait for them, or install a handler that is called when +the signal fires. + +=item * Condition variables are like "Merge Points" - points in your program +where you merge multiple independent results/control flows into one. + +=item * Condition variables represent a transaction - functions that start +some kind of transaction can return them, leaving the caller the choice +between waiting in a blocking fashion, or setting a callback. + +=item * Condition variables represent future values, or promises to deliver +some result, long before the result is available. + +=back Condition variables are very useful to signal that something has finished, for example, if you write a module that does asynchronous http requests, @@ -419,7 +620,7 @@ used by AnyEvent itself are all named C<_ae_XXX> to make subclassing easy (it is often useful to build your own transaction class on top of AnyEvent). To subclass, use C as base class and call -it's C method in your own C method. +its C method in your own C method. There are two "sides" to a condition variable - the "producer side" which eventually calls C<< -> send >>, and the "consumer side", which waits @@ -427,29 +628,46 @@ Example: wait for a timer. - # wait till the result is ready - my $result_ready = AnyEvent->condvar; + # condition: "wait till the timer is fired" + my $timer_fired = AnyEvent->condvar; - # do something such as adding a timer - # or socket watcher the calls $result_ready->send - # when the "result" is ready. + # create the timer - we could wait for, say + # a handle becomign ready, or even an + # AnyEvent::HTTP request to finish, but # in this case, we simply use a timer: my $w = AnyEvent->timer ( after => 1, - cb => sub { $result_ready->send }, + cb => sub { $timer_fired->send }, ); # this "blocks" (while handling events) till the callback - # calls send - $result_ready->recv; + # calls ->send + $timer_fired->recv; -Example: wait for a timer, but take advantage of the fact that -condition variables are also code references. +Example: wait for a timer, but take advantage of the fact that condition +variables are also callable directly. my $done = AnyEvent->condvar; my $delay = AnyEvent->timer (after => 5, cb => $done); $done->recv; +Example: Imagine an API that returns a condvar and doesn't support +callbacks. This is how you make a synchronous call, for example from +the main program: + + use AnyEvent::CouchDB; + + ... + + my @info = $couchdb->info->recv; + +And this is how you would just set a callback to be called whenever the +results are available: + + $couchdb->info->cb (sub { + my @info = $_[0]->recv; + }); + =head3 METHODS FOR PRODUCERS These methods should only be used by the producing side, i.e. the @@ -471,45 +689,73 @@ Any arguments passed to the C call will be returned by all future C<< ->recv >> calls. -Condition variables are overloaded so one can call them directly -(as a code reference). Calling them directly is the same as calling -C. Note, however, that many C-based event loops do not handle -overloading, so as tempting as it may be, passing a condition variable -instead of a callback does not work. Both the pure perl and EV loops -support overloading, however, as well as all functions that use perl to -invoke a callback (as in L and L for -example). +Condition variables are overloaded so one can call them directly (as if +they were a code reference). Calling them directly is the same as calling +C. =item $cv->croak ($error) -Similar to send, but causes all call's to C<< ->recv >> to invoke +Similar to send, but causes all calls to C<< ->recv >> to invoke C with the given error message/object/scalar. This can be used to signal any errors to the condition variable -user/consumer. +user/consumer. Doing it this way instead of calling C directly +delays the error detection, but has the overwhelming advantage that it +diagnoses the error at the place where the result is expected, and not +deep in some event callback with no connection to the actual code causing +the problem. =item $cv->begin ([group callback]) =item $cv->end -These two methods are EXPERIMENTAL and MIGHT CHANGE. - These two methods can be used to combine many transactions/events into one. For example, a function that pings many hosts in parallel might want to use a condition variable for the whole process. Every call to C<< ->begin >> will increment a counter, and every call to C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end ->>, the (last) callback passed to C will be executed. That callback -is I to call C<< ->send >>, but that is not required. If no -callback was set, C will be called without any arguments. +>>, the (last) callback passed to C will be executed, passing the +condvar as first argument. That callback is I to call C<< ->send +>>, but that is not required. If no group callback was set, C will +be called without any arguments. + +You can think of C<< $cv->send >> giving you an OR condition (one call +sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND +condition (all C calls must be C'ed before the condvar sends). + +Let's start with a simple example: you have two I/O watchers (for example, +STDOUT and STDERR for a program), and you want to wait for both streams to +close before activating a condvar: + + my $cv = AnyEvent->condvar; + + $cv->begin; # first watcher + my $w1 = AnyEvent->io (fh => $fh1, cb => sub { + defined sysread $fh1, my $buf, 4096 + or $cv->end; + }); + + $cv->begin; # second watcher + my $w2 = AnyEvent->io (fh => $fh2, cb => sub { + defined sysread $fh2, my $buf, 4096 + or $cv->end; + }); + + $cv->recv; -Let's clarify this with the ping example: +This works because for every event source (EOF on file handle), there is +one call to C, so the condvar waits for all calls to C before +sending. + +The ping example mentioned above is slightly more complicated, as the +there are results to be passwd back, and the number of tasks that are +begun can potentially be zero: my $cv = AnyEvent->condvar; my %result; - $cv->begin (sub { $cv->send (\%result) }); + $cv->begin (sub { shift->send (\%result) }); for my $host (@list_of_hosts) { $cv->begin; @@ -534,10 +780,11 @@ C is called even when C hosts are being pinged (the loop doesn't execute once). -This is the general pattern when you "fan out" into multiple subrequests: -use an outer C/C pair to set the callback and ensure C -is called at least once, and then, for each subrequest you start, call -C and for each subrequest you finish, call C. +This is the general pattern when you "fan out" into multiple (but +potentially zero) subrequests: use an outer C/C pair to set +the callback and ensure C is called at least once, and then, for each +subrequest you start, call C and for each subrequest you finish, +call C. =back @@ -551,7 +798,7 @@ =item $cv->recv Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak ->> methods have been called on c<$cv>, while servicing other watchers +>> methods have been called on C<$cv>, while servicing other watchers normally. You can only wait once on a condition - additional calls are valid but @@ -563,26 +810,22 @@ In list context, all parameters passed to C will be returned, in scalar context only the first one will be returned. +Note that doing a blocking wait in a callback is not supported by any +event loop, that is, recursive invocation of a blocking C<< ->recv +>> is not allowed, and the C call will C if such a +condition is detected. This condition can be slightly loosened by using +L, which allows you to do a blocking C<< ->recv >> from +any thread that doesn't run the event loop itself. + Not all event models support a blocking wait - some die in that case (programs might want to do that to stay interactive), so I, but let the +using this from a module, never require a blocking wait>. Instead, let the caller decide whether 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 supporting blocking waits if the caller so desires). -Another reason I to C<< ->recv >> in a module is that you cannot -sensibly have two C<< ->recv >>'s in parallel, as that would require -multiple interpreters or coroutines/threads, none of which C -can supply. - -The L module, however, I and I supply coroutines and, in -fact, L replaces AnyEvent's condvars by coroutine-safe -versions and also integrates coroutines into AnyEvent, making blocking -C<< ->recv >> calls perfectly safe as long as they are done from another -coroutine (one that doesn't run the event loop). - -You can ensure that C<< -recv >> never blocks by setting a callback and +You can ensure that C<< ->recv >> never blocks by setting a callback and only calling C<< ->recv >> from within that callback (or at a later time). This will work even when the event loop does not support blocking waits otherwise. @@ -592,78 +835,175 @@ Returns true when the condition is "true", i.e. whether C or C have been called. -=item $cb = $cv->cb ([new callback]) +=item $cb = $cv->cb ($cb->($cv)) This is a mutator function that returns the callback set and optionally replaces it before doing so. The callback will be called when the condition becomes "true", i.e. when -C or C are called, with the only argument being the condition -variable itself. Calling C inside the callback or at any later time -is guaranteed not to block. +C or C are called, with the only argument being the +condition variable itself. If the condition is already true, the +callback is called immediately when it is set. Calling C inside +the callback or at any later time is guaranteed not to block. =back -=head1 GLOBAL VARIABLES AND FUNCTIONS +=head1 SUPPORTED EVENT LOOPS/BACKENDS -=over 4 +The available backend classes are (every class has its own manpage): -=item $AnyEvent::MODEL +=over 4 -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). +=item Backends that are autoprobed when no other event loop can be found. -The known classes so far are: +EV is the preferred backend when no other event loop seems to be in +use. If EV is not installed, then AnyEvent will fall back to its own +pure-perl implementation, which is available everywhere as it comes with +AnyEvent itself. - AnyEvent::Impl::EV based on EV (an interface to libev, best choice). - AnyEvent::Impl::Event based on Event, second best choice. + AnyEvent::Impl::EV based on EV (interface to libev, best choice). AnyEvent::Impl::Perl pure-perl implementation, fast and portable. - AnyEvent::Impl::Glib based on Glib, third-best choice. - AnyEvent::Impl::Tk based on Tk, very bad choice. - AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). + +=item Backends that are transparently being picked up when they are used. + +These will be used if they are already loaded when the first watcher +is created, in which case it is assumed that the application is using +them. This means that AnyEvent will automatically pick the right backend +when the main program loads an event module before anything starts to +create watchers. Nothing special needs to be done by the main program. + + AnyEvent::Impl::Event based on Event, very stable, few glitches. + AnyEvent::Impl::Glib based on Glib, slow but very stable. + AnyEvent::Impl::Tk based on Tk, very broken. AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. - AnyEvent::Impl::POE based on POE, not generic enough for full support. + AnyEvent::Impl::POE based on POE, very slow, some limitations. + AnyEvent::Impl::Irssi used when running within irssi. + AnyEvent::Impl::IOAsync based on IO::Async. + +=item Backends with special needs. + +Qt requires the Qt::Application to be instantiated first, but will +otherwise be picked up automatically. As long as the main program +instantiates the application before any AnyEvent watchers are created, +everything should just work. + + AnyEvent::Impl::Qt based on Qt. -There is no support for WxWidgets, as WxWidgets has no support for -watching file handles. However, you can use WxWidgets through the -POE Adaptor, as POE has a Wx backend that simply polls 20 times per -second, which was considered to be too horrible to even consider for -AnyEvent. Likewise, other POE backends can be used by AnyEvent by using -it's adaptor. +=item Event loops that are indirectly supported via other backends. -AnyEvent knows about L and L and will try to use L when -autodetecting them. +Some event loops can be supported via other modules: + +There is no direct support for WxWidgets (L) or L. + +B has no support for watching file handles. However, you can +use WxWidgets through the POE adaptor, as POE has a Wx backend that simply +polls 20 times per second, which was considered to be too horrible to even +consider for AnyEvent. + +B is not supported as nobody seems to be using it, but it has a POE +backend, so it can be supported through POE. + +AnyEvent knows about both L and L, however, and will try to +load L when detecting them, in the hope that POE will pick them up, +in which case everything will be automatic. + +=back + +=head1 GLOBAL VARIABLES AND FUNCTIONS + +These are not normally required to use AnyEvent, but can be useful to +write AnyEvent extension modules. + +=over 4 + +=item $AnyEvent::MODEL + +Contains C until the first watcher is being created, before the +backend has been autodetected. + +Afterwards it contains the event model that is being used, which is the +name of the Perl class implementing the model. This class is usually one +of the C modules, but can be any other class in the +case AnyEvent has been extended at runtime (e.g. in I it +will be C). =item AnyEvent::detect Returns C<$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, as late as possible at -runtime. +runtime, and not e.g. during initialisation of your module. + +If you need to do some initialisation before AnyEvent watchers are +created, use C. =item $guard = AnyEvent::post_detect { BLOCK } Arranges for the code block to be executed as soon as the event model is -autodetected (or immediately if this has already happened). +autodetected (or immediately if that has already happened). + +The block will be executed I the actual backend has been detected +(C<$AnyEvent::MODEL> is set), but I any watchers have been +created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do +other initialisations - see the sources of L or +L to see how this is used. + +The most common usage is to create some global watchers, without forcing +event module detection too early, for example, L creates +and installs the global L watcher in a C block to +avoid autodetecting the event module at load time. If called in scalar or list context, then it creates and returns an object -that automatically removes the callback again when it is destroyed. See -L for a case where this is useful. +that automatically removes the callback again when it is destroyed (or +C when the hook was immediately executed). See L for +a case where this is useful. + +Example: Create a watcher for the IO::AIO module and store it in +C<$WATCHER>, but do so only do so after the event loop is initialised. + + our WATCHER; + + my $guard = AnyEvent::post_detect { + $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); + }; + + # the ||= is important in case post_detect immediately runs the block, + # as to not clobber the newly-created watcher. assigning both watcher and + # post_detect guard to the same variable has the advantage of users being + # able to just C if the watcher causes them grief. + + $WATCHER ||= $guard; =item @AnyEvent::post_detect If there are any code references in this array (you can C to it -before or after loading AnyEvent), then they will called directly after -the event loop has been chosen. +before or after loading AnyEvent), then they will be called directly +after the event loop has been chosen. You should check C<$AnyEvent::MODEL> before adding to this array, though: -if it contains a true value then the event loop has already been detected, -and the array will be ignored. +if it is defined then the event loop has already been detected, and the +array will be ignored. -Best use C instead. +Best use C when your application allows +it, as it takes care of these details. + +This variable is mainly useful for modules that can do something useful +when AnyEvent is used and thus want to know when it is initialised, but do +not need to even load it by default. This array provides the means to hook +into AnyEvent passively, without loading it. + +Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used +together, you could put this into Coro (this is the actual code used by +Coro to accomplish this): + + if (defined $AnyEvent::MODEL) { + # AnyEvent already initialised, so load Coro::AnyEvent + require Coro::AnyEvent; + } else { + # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent + # as soon as it is + push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; + } =back @@ -684,17 +1024,19 @@ It is fine, however, to call C<< ->recv >> when the user of your module requests it (i.e. if you create a http request object ad have a method -called C that returns the results, it should call C<< ->recv >> -freely, as the user of your module knows what she is doing. always). +called C that returns the results, it may call C<< ->recv >> +freely, as the user of your module knows what she is doing. Always). =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 (it does not need to be event-based) and let AnyEvent -decide which implementation to chose if some module relies on it. +If the program is not event-based, it need not do anything special, even +when it depends on a module that uses an AnyEvent. If the program itself +uses AnyEvent, but does not care which event loop is used, all it needs +to do is C. In either case, AnyEvent will choose the best +available loop implementation. If the main program relies on a specific event model - for example, in Gtk2 programs you have to rely on the Glib module - you should load the @@ -702,7 +1044,7 @@ speaking, you should load it 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. +might choose the wrong one unless you load the correct one yourself. You can chose to use a pure-perl implementation by loading the C module, which gives you similar behaviour @@ -728,16 +1070,16 @@ =head1 OTHER MODULES The following is a non-exhaustive list of additional modules that use -AnyEvent and can therefore be mixed easily with other AnyEvent modules -in the same program. Some of the modules come with AnyEvent, some are -available via CPAN. +AnyEvent as a client and can therefore be mixed easily with other AnyEvent +modules and other event loops in the same program. Some of the modules +come as part of AnyEvent, the others are available via CPAN. =over 4 =item L -Contains various utility functions that replace often-used but blocking -functions such as C by event-/callback-based versions. +Contains various utility functions that replace often-used blocking +functions such as C with event/callback-based versions. =item L @@ -749,86 +1091,78 @@ Provide read and write buffers, manages watchers for reads and writes, supports raw and formatted I/O, I/O queued and fully transparent and -non-blocking SSL/TLS. +non-blocking SSL/TLS (via L). =item L Provides rich asynchronous DNS resolver capabilities. -=item L - -A simple-to-use HTTP library that is capable of making a lot of concurrent -HTTP requests. - -=item L - -Provides a simple web application server framework. - -=item L +=item L, L, L, L, L, L -The fastest ping in the west. +Implement event-based interfaces to the protocols of the same name (for +the curious, IGS is the International Go Server and FCP is the Freenet +Client Protocol). + +=item L + +Here be danger! + +As Pauli would put it, "Not only is it not right, it's not even wrong!" - +there are so many things wrong with AnyEvent::Handle::UDP, most notably +its use of a stream-based API with a protocol that isn't streamable, that +the only way to improve it is to delete it. + +It features data corruption (but typically only under load) and general +confusion. On top, the author is not only clueless about UDP but also +fact-resistant - some gems of his understanding: "connect doesn't work +with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not +packets", "I don't need to implement proper error checking as UDP doesn't +support error checking" and so on - he doesn't even understand what's +wrong with his module when it is explained to him. =item L -Executes L requests asynchronously in a proxy process. +Executes L requests asynchronously in a proxy process for you, +notifying you in an event-based way when the operation is finished. =item L -Truly asynchronous I/O, should be in the toolbox of every event -programmer. AnyEvent::AIO transparently fuses L and AnyEvent -together. - -=item L - -Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses -L and AnyEvent together. +Truly asynchronous (as opposed to non-blocking) I/O, should be in the +toolbox of every event programmer. AnyEvent::AIO transparently fuses +L and AnyEvent together, giving AnyEvent access to event-based +file I/O, and much more. -=item L - -A non-blocking interface to gpsd, a daemon delivering GPS information. - -=item L - -A non-blocking interface to the Internet Go Server protocol (used by -L). - -=item L - -AnyEvent based IRC client module family. - -=item L - -AnyEvent based XMPP (Jabber protocol) module family. - -=item L +=item L -AnyEvent-based implementation of the Freenet Client Protocol, birthplace -of AnyEvent. +A simple embedded webserver. -=item L +=item L -High level API for event-based execution flow control. +The fastest ping in the west. =item L Has special support for AnyEvent via L. -=item L - -The lambda approach to I/O - don't ask, look there. Can use AnyEvent. - =back =cut package AnyEvent; -no warnings; -use strict; +# basically a tuned-down version of common::sense +sub common_sense { + # from common:.sense 3.3 + ${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf3\x0f\xc0\xf0\xfc\x33\x00"; + # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl) + $^H |= 0x00000600; +} + +BEGIN { AnyEvent::common_sense } -use Carp; +use Carp (); -our $VERSION = 4.2; +our $VERSION = '5.29'; our $MODEL; our $AUTOLOAD; @@ -836,14 +1170,21 @@ our @REGISTRY; -our $WIN32; +our $VERBOSE; BEGIN { - my $win32 = ! ! ($^O =~ /mswin32/i); - eval "sub WIN32(){ $win32 }"; + require "AnyEvent/constants.pl"; + + eval "sub TAINT (){" . (${^TAINT}*1) . "}"; + + delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} + if ${^TAINT}; + + $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1; + } -our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; +our $MAX_SIGNAL_LATENCY = 10; our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred @@ -855,101 +1196,119 @@ } my @models = ( - [EV:: => AnyEvent::Impl::EV::], - [Event:: => AnyEvent::Impl::Event::], - [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], - # everything below here will not be autoprobed + [EV:: => AnyEvent::Impl::EV:: , 1], + [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1], + # everything below here will not (normally) be autoprobed # as the pureperl backend should work everywhere # and is usually faster - [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles - [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers + [Event:: => AnyEvent::Impl::Event::, 1], + [Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy + [Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package + [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles [Qt:: => AnyEvent::Impl::Qt::], # requires special main program [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza [Wx:: => AnyEvent::Impl::POE::], [Prima:: => AnyEvent::Impl::POE::], + [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], ); -our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); +our %method = map +($_ => 1), + qw(io timer time now now_update signal child idle condvar one_event DESTROY); our @post_detect; sub post_detect(&) { my ($cb) = @_; - if ($MODEL) { - $cb->(); - - 1 - } else { - push @post_detect, $cb; + push @post_detect, $cb; - defined wantarray - ? bless \$cb, "AnyEvent::Util::PostDetect" - : () - } + defined wantarray + ? bless \$cb, "AnyEvent::Util::postdetect" + : () } -sub AnyEvent::Util::PostDetect::DESTROY { +sub AnyEvent::Util::postdetect::DESTROY { @post_detect = grep $_ != ${$_[0]}, @post_detect; } sub detect() { - unless ($MODEL) { - no strict 'refs'; - local $SIG{__DIE__}; + # free some memory + *detect = sub () { $MODEL }; - if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { - my $model = "AnyEvent::Impl::$1"; - if (eval "require $model") { - $MODEL = $model; - warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; - } else { - warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; + local $!; # for good measure + local $SIG{__DIE__}; + + if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { + my $model = "AnyEvent::Impl::$1"; + if (eval "require $model") { + $MODEL = $model; + warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2; + } else { + warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE; + } + } + + # check for already loaded models + unless ($MODEL) { + for (@REGISTRY, @models) { + my ($package, $model) = @$_; + if (${"$package\::VERSION"} > 0) { + if (eval "require $model") { + $MODEL = $model; + warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2; + last; + } } } - # check for already loaded models unless ($MODEL) { + # try to autoload a model for (@REGISTRY, @models) { - my ($package, $model) = @$_; - if (${"$package\::VERSION"} > 0) { - if (eval "require $model") { - $MODEL = $model; - warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; - last; - } + my ($package, $model, $autoload) = @$_; + if ( + $autoload + and eval "require $package" + and ${"$package\::VERSION"} > 0 + and eval "require $model" + ) { + $MODEL = $model; + warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2; + last; } } - unless ($MODEL) { - # try to load a model - - for (@REGISTRY, @models) { - my ($package, $model) = @$_; - if (eval "require $package" - and ${"$package\::VERSION"} > 0 - and eval "require $model") { - $MODEL = $model; - warn "AnyEvent: autoprobed model '$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: EV, Event or Glib."; - } + $MODEL + or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n"; } + } - push @{"$MODEL\::ISA"}, "AnyEvent::Base"; + @models = (); # free probe data - unshift @ISA, $MODEL; + push @{"$MODEL\::ISA"}, "AnyEvent::Base"; + unshift @ISA, $MODEL; - require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT}; + # now nuke some methods that are overridden by the backend. + # SUPER is not allowed. + for (qw(time signal child idle)) { + undef &{"AnyEvent::Base::$_"} + if defined &{"$MODEL\::$_"}; + } - (shift @post_detect)->() while @post_detect; + if ($ENV{PERL_ANYEVENT_STRICT}) { + eval { require AnyEvent::Strict }; + warn "AnyEvent: cannot load AnyEvent::Strict: $@" + if $@ && $VERBOSE; } + (shift @post_detect)->() while @post_detect; + + *post_detect = sub(&) { + shift->(); + + undef + }; + $MODEL } @@ -957,9 +1316,9 @@ (my $func = $AUTOLOAD) =~ s/.*://; $method{$func} - or croak "$func: not a valid method for AnyEvent objects"; + or Carp::croak "$func: not a valid AnyEvent class method"; - detect unless $MODEL; + detect; my $class = shift; $class->$func (@_); @@ -968,63 +1327,288 @@ # utility function to dup a filehandle. this is used by many backends # to support binding more than one watcher per filehandle (they usually # allow only one watcher per fd, so we dup it to get a different one). -sub _dupfh($$$$) { +sub _dupfh($$;$$) { my ($poll, $fh, $r, $w) = @_; - require Fcntl; - # cygwin requires the fh mode to be matching, unix doesn't - my ($rw, $mode) = $poll eq "r" ? ($r, "<") - : $poll eq "w" ? ($w, ">") - : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'"; + my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&"); - open my $fh2, "$mode&" . fileno $fh - or die "cannot dup() filehandle: $!"; + open my $fh2, $mode, $fh + or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,"; # we assume CLOEXEC is already set by perl in all important cases ($fh2, $rw) } +=head1 SIMPLIFIED AE API + +Starting with version 5.0, AnyEvent officially supports a second, much +simpler, API that is designed to reduce the calling, typing and memory +overhead by using function call syntax and a fixed number of parameters. + +See the L manpage for details. + +=cut + +package AE; + +our $VERSION = $AnyEvent::VERSION; + +# fall back to the main API by default - backends and AnyEvent::Base +# implementations can overwrite these. + +sub io($$$) { + AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2]) +} + +sub timer($$$) { + AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2]) +} + +sub signal($$) { + AnyEvent->signal (signal => $_[0], cb => $_[1]) +} + +sub child($$) { + AnyEvent->child (pid => $_[0], cb => $_[1]) +} + +sub idle($) { + AnyEvent->idle (cb => $_[0]) +} + +sub cv(;&) { + AnyEvent->condvar (@_ ? (cb => $_[0]) : ()) +} + +sub now() { + AnyEvent->now +} + +sub now_update() { + AnyEvent->now_update +} + +sub time() { + AnyEvent->time +} + package AnyEvent::Base; -# default implementation for now and time +# default implementations for many methods -use Time::HiRes (); +sub time { + eval q{ # poor man's autoloading {} + # probe for availability of Time::HiRes + if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { + warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8; + *AE::time = \&Time::HiRes::time; + # if (eval "use POSIX (); (POSIX::times())... + } else { + warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE; + *AE::time = sub (){ time }; # epic fail + } + + *time = sub { AE::time }; # different prototypes + }; + die if $@; + + &time +} + +*now = \&time; -sub time { Time::HiRes::time } -sub now { Time::HiRes::time } +sub now_update { } # default implementation for ->condvar sub condvar { - bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: + eval q{ # poor man's autoloading {} + *condvar = sub { + bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" + }; + + *AE::cv = sub (;&) { + bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar" + }; + }; + die if $@; + + &condvar } # default implementation for ->signal -our %SIG_CB; +our $HAVE_ASYNC_INTERRUPT; -sub signal { - my (undef, %arg) = @_; - - my $signal = uc $arg{signal} - or Carp::croak "required option 'signal' is missing"; +sub _have_async_interrupt() { + $HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} + && eval "use Async::Interrupt 1.02 (); 1") + unless defined $HAVE_ASYNC_INTERRUPT; + + $HAVE_ASYNC_INTERRUPT +} + +our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); +our (%SIG_ASY, %SIG_ASY_W); +our ($SIG_COUNT, $SIG_TW); + +# install a dummy wakeup watcher to reduce signal catching latency +# used by Impls +sub _sig_add() { + unless ($SIG_COUNT++) { + # try to align timer on a full-second boundary, if possible + my $NOW = AE::now; + + $SIG_TW = AE::timer + $MAX_SIGNAL_LATENCY - ($NOW - int $NOW), + $MAX_SIGNAL_LATENCY, + sub { } # just for the PERL_ASYNC_CHECK + ; + } +} - $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; - $SIG{$signal} ||= sub { - $_->() for values %{ $SIG_CB{$signal} || {} }; +sub _sig_del { + undef $SIG_TW + unless --$SIG_COUNT; +} + +our $_sig_name_init; $_sig_name_init = sub { + eval q{ # poor man's autoloading {} + undef $_sig_name_init; + + if (_have_async_interrupt) { + *sig2num = \&Async::Interrupt::sig2num; + *sig2name = \&Async::Interrupt::sig2name; + } else { + require Config; + + my %signame2num; + @signame2num{ split ' ', $Config::Config{sig_name} } + = split ' ', $Config::Config{sig_num}; + + my @signum2name; + @signum2name[values %signame2num] = keys %signame2num; + + *sig2num = sub($) { + $_[0] > 0 ? shift : $signame2num{+shift} + }; + *sig2name = sub ($) { + $_[0] > 0 ? $signum2name[+shift] : shift + }; + } }; + die if $@; +}; - bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" -} +sub sig2num ($) { &$_sig_name_init; &sig2num } +sub sig2name($) { &$_sig_name_init; &sig2name } + +sub signal { + eval q{ # poor man's autoloading {} + # probe for availability of Async::Interrupt + if (_have_async_interrupt) { + warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8; + + $SIGPIPE_R = new Async::Interrupt::EventPipe; + $SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec; + + } else { + warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8; + + if (AnyEvent::WIN32) { + require AnyEvent::Util; + + ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe (); + AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R; + AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case + } else { + pipe $SIGPIPE_R, $SIGPIPE_W; + fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R; + fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case + + # not strictly required, as $^F is normally 2, but let's make sure... + fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC; + fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC; + } + + $SIGPIPE_R + or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; + + $SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec; + } -sub AnyEvent::Base::Signal::DESTROY { - my ($signal, $cb) = @{$_[0]}; + *signal = $HAVE_ASYNC_INTERRUPT + ? sub { + my (undef, %arg) = @_; + + # async::interrupt + my $signal = sig2num $arg{signal}; + $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; + + $SIG_ASY{$signal} ||= new Async::Interrupt + cb => sub { undef $SIG_EV{$signal} }, + signal => $signal, + pipe => [$SIGPIPE_R->filenos], + pipe_autodrain => 0, + ; + + bless [$signal, $arg{cb}], "AnyEvent::Base::signal" + } + : sub { + my (undef, %arg) = @_; + + # pure perl + my $signal = sig2name $arg{signal}; + $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; + + $SIG{$signal} ||= sub { + local $!; + syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV; + undef $SIG_EV{$signal}; + }; + + # can't do signal processing without introducing races in pure perl, + # so limit the signal latency. + _sig_add; + + bless [$signal, $arg{cb}], "AnyEvent::Base::signal" + } + ; + + *AnyEvent::Base::signal::DESTROY = sub { + my ($signal, $cb) = @{$_[0]}; + + _sig_del; + + delete $SIG_CB{$signal}{$cb}; + + $HAVE_ASYNC_INTERRUPT + ? delete $SIG_ASY{$signal} + : # delete doesn't work with older perls - they then + # print weird messages, or just unconditionally exit + # instead of getting the default action. + undef $SIG{$signal} + unless keys %{ $SIG_CB{$signal} }; + }; - delete $SIG_CB{$signal}{$cb}; + *_signal_exec = sub { + $HAVE_ASYNC_INTERRUPT + ? $SIGPIPE_R->drain + : sysread $SIGPIPE_R, (my $dummy), 9; + + while (%SIG_EV) { + for (keys %SIG_EV) { + delete $SIG_EV{$_}; + $_->() for values %{ $SIG_CB{$_} || {} }; + } + } + }; + }; + die if $@; - delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; + &signal } # default implementation for ->child @@ -1032,65 +1616,122 @@ 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; - }); +# used by many Impl's +sub _emit_childstatus($$) { + my (undef, $rpid, $rstatus) = @_; + + $_->($rpid, $rstatus) + for values %{ $PID_CB{$rpid} || {} }, + values %{ $PID_CB{0} || {} }; } sub child { - my (undef, %arg) = @_; + eval q{ # poor man's autoloading {} + *_sigchld = sub { + my $pid; - defined (my $pid = $arg{pid} + 0) - or Carp::croak "required option 'pid' is missing"; + AnyEvent->_emit_childstatus ($pid, $?) + while ($pid = waitpid -1, WNOHANG) > 0; + }; - $PID_CB{$pid}{$arg{cb}} = $arg{cb}; + *child = sub { + my (undef, %arg) = @_; - unless ($WNOHANG) { - $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; - } + defined (my $pid = $arg{pid} + 0) + or Carp::croak "required option 'pid' is missing"; - unless ($CHLD_W) { - $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); - # child could be a zombie already, so make at least one round - &_sigchld; - } + $PID_CB{$pid}{$arg{cb}} = $arg{cb}; + + unless ($CHLD_W) { + $CHLD_W = AE::signal CHLD => \&_sigchld; + # child could be a zombie already, so make at least one round + &_sigchld; + } + + bless [$pid, $arg{cb}], "AnyEvent::Base::child" + }; - bless [$pid, $arg{cb}], "AnyEvent::Base::Child" + *AnyEvent::Base::child::DESTROY = sub { + my ($pid, $cb) = @{$_[0]}; + + delete $PID_CB{$pid}{$cb}; + delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; + + undef $CHLD_W unless keys %PID_CB; + }; + }; + die if $@; + + &child } -sub AnyEvent::Base::Child::DESTROY { - my ($pid, $cb) = @{$_[0]}; +# idle emulation is done by simply using a timer, regardless +# of whether the process is idle or not, and not letting +# the callback use more than 50% of the time. +sub idle { + eval q{ # poor man's autoloading {} + *idle = sub { + my (undef, %arg) = @_; + + my ($cb, $w, $rcb) = $arg{cb}; + + $rcb = sub { + if ($cb) { + $w = _time; + &$cb; + $w = _time - $w; + + # never use more then 50% of the time for the idle watcher, + # within some limits + $w = 0.0001 if $w < 0.0001; + $w = 5 if $w > 5; + + $w = AE::timer $w, 0, $rcb; + } else { + # clean up... + undef $w; + undef $rcb; + } + }; - delete $PID_CB{$pid}{$cb}; - delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; + $w = AE::timer 0.05, 0, $rcb; - undef $CHLD_W unless keys %PID_CB; + bless \\$cb, "AnyEvent::Base::idle" + }; + + *AnyEvent::Base::idle::DESTROY = sub { + undef $${$_[0]}; + }; + }; + die if $@; + + &idle } package AnyEvent::CondVar; our @ISA = AnyEvent::CondVar::Base::; +# only to be used for subclassing +sub new { + my $class = shift; + bless AnyEvent->condvar (@_), $class +} + package AnyEvent::CondVar::Base; -use overload - '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, - fallback => 1; +#use overload +# '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, +# fallback => 1; + +# save 300+ kilobytes by dirtily hardcoding overloading +${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching. +*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod." +*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{} +${'AnyEvent::CondVar::Base::()'} = 1; # fallback + +our $WAITING; sub _send { # nop @@ -1113,6 +1754,11 @@ } sub _wait { + $WAITING + and !$_[0]{_ae_sent} + and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected"; + + local $WAITING = 1; AnyEvent->one_event while !$_[0]{_ae_sent}; } @@ -1124,8 +1770,14 @@ } sub cb { - $_[0]{_ae_cb} = $_[1] if @_ > 1; - $_[0]{_ae_cb} + my $cv = shift; + + @_ + and $cv->{_ae_cb} = shift + and $cv->{_ae_sent} + and (delete $cv->{_ae_cb})->($cv); + + $cv->{_ae_cb} } sub begin { @@ -1142,52 +1794,32 @@ *broadcast = \&send; *wait = \&_wait; -=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE - -This is an advanced topic that you do not normally need to use AnyEvent in -a module. This section is only of use to event loop authors who want to -provide AnyEvent compatibility. - -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, so it is reasonably cheap. - -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 already loaded. - -When AnyEvent is loaded and asked to find a suitable event model, it -will first check for the presence of urxvt by trying to C the -C module. - -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. +=head1 ERROR AND EXCEPTION HANDLING -If you don't provide C and C watchers than AnyEvent will -provide suitable (hopefully) replacements. - -The above example isn't fictitious, the I (a.k.a. urxvt) -terminal emulator 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 done in an interactive application, so it makes sense. +In general, AnyEvent does not do any error handling - it relies on the +caller to do that if required. The L module (see also +the C environment variable, below) provides strict +checking of all AnyEvent methods, however, which is highly useful during +development. + +As for exception handling (i.e. runtime errors and exceptions thrown while +executing a callback), this is not only highly event-loop specific, but +also not in any way wrapped by this module, as this is the job of the main +program. + +The pure perl event loop simply re-throws the exception (usually +within C<< condvar->recv >>), the L and L modules call C<< +$Event/EV::DIED->() >>, L uses C<< install_exception_handler >> and +so on. =head1 ENVIRONMENT VARIABLES -The following environment variables are used by this module: +The following environment variables are used by this module or its +submodules. + +Note that AnyEvent will remove I environment variables starting with +C from C<%ENV> when it is loaded while taint mode is +enabled. =over 4 @@ -1204,18 +1836,23 @@ When set to C<2> or higher, cause AnyEvent to report to STDERR which event model it chooses. +When set to C<8> or higher, then AnyEvent will report extra information on +which optional modules it loads and how it implements certain features. + =item C AnyEvent does not do much argument checking by default, as thorough argument checking is very costly. Setting this variable to a true value will cause AnyEvent to load C and then to thoroughly -check the arguments passed to most method calls. If it finds any problems +check the arguments passed to most method calls. If it finds any problems, it will croak. In other words, enables "strict" mode. -Unlike C it is definitely recommended ot keep it off in -production. +Unlike C (or its modern cousin, C<< use L +>>, it is definitely recommended to keep it off in production. Keeping +C in your environment while developing programs +can be very useful, however. =item C @@ -1246,7 +1883,7 @@ This variable can effectively be used for denial-of-service attacks against local programs (e.g. when setuid), although the impact is likely -small, as the program has to handle connection errors already- +small, as the program has to handle conenction and other failures anyways. Examples: C - prefer IPv4 over IPv6, but support both and try to use both. C @@ -1269,8 +1906,75 @@ The maximum number of child processes that C will create in parallel. +=item C + +The default value for the C parameter for the default DNS +resolver - this is the maximum number of parallel DNS requests that are +sent to the DNS server. + +=item C + +The file to use instead of F (or OS-specific +configuration) in the default resolver. When set to the empty string, no +default config will be used. + +=item C, C. + +When neither C nor C was specified during +L context creation, and either of these environment +variables exist, they will be used to specify CA certificate locations +instead of a system-dependent default. + +=item C and C + +When these are set to C<1>, then the respective modules are not +loaded. Mostly good for testing AnyEvent itself. + =back +=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE + +This is an advanced topic that you do not normally need to use AnyEvent in +a module. This section is only of use to event loop authors who want to +provide AnyEvent compatibility. + +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, so it is reasonably cheap. + +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 already loaded. + +When AnyEvent is loaded and asked to find a suitable event model, it +will first check for the presence of urxvt by trying to C the +C module. + +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. + +If you don't provide C and C watchers than AnyEvent will +provide suitable (hopefully) replacements. + +The above example isn't fictitious, the I (a.k.a. urxvt) +terminal emulator 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 done in an interactive application, so it makes sense. + =head1 EXAMPLE PROGRAM The following program uses an I/O watcher to read data from STDIN, a timer @@ -1292,16 +1996,9 @@ }, ); - my $time_watcher; # can only be used once - - sub new_timer { - $timer = AnyEvent->timer (after => 1, cb => sub { - warn "timeout\n"; # print 'timeout' about every second - &new_timer; # and restart the time - }); - } - - new_timer; # create first timer + my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub { + warn "timeout\n"; # print 'timeout' at most every second + }); $cv->recv; # wait until user enters /^q/i @@ -1384,7 +2081,7 @@ that occurred during request processing. The C method detects whether an exception as thrown (it is stored inside the $txn object) and just throws the exception, which means connection errors and other -problems get reported tot he code that tries to use the result, not in a +problems get reported to the code that tries to use the result, not in a random callback. All of this enables the following usage styles: @@ -1442,7 +2139,8 @@ which it is), lets them fire exactly once and destroys them again. Source code for this benchmark is found as F in the AnyEvent -distribution. +distribution. It uses the L interface, which makes a real difference +for the EV and Perl backends only. =head3 Explanation of the columns @@ -1473,16 +2171,18 @@ =head3 Results name watchers bytes create invoke destroy comment - EV/EV 400000 244 0.56 0.46 0.31 EV native interface - EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers - CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal - Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation - Event/Event 16000 516 31.88 31.30 0.85 Event native interface - Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers - Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour - Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers - POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event - POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select + EV/EV 100000 223 0.47 0.43 0.27 EV native interface + EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers + Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal + Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation + Event/Event 16000 516 31.16 31.84 0.82 Event native interface + Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers + IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll + IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll + Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour + Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers + POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event + POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select =head3 Discussion @@ -1504,9 +2204,10 @@ cycles with POE. C is the sole leader regarding speed and memory use, which are both -maximal/minimal, respectively. Even when going through AnyEvent, it uses -far less memory than any other event loop and is still faster than Event -natively. +maximal/minimal, respectively. When using the L API there is zero +overhead (when going through the AnyEvent API create is about 5-6 times +slower, with other times being equal, so still uses far less memory than +any other event loop and is still faster than Event natively). The pure perl implementation is hit in a few sweet spots (both the constant timeout and the use of a single fd hit optimisations in the perl @@ -1518,6 +2219,9 @@ The C module has a relatively high setup and callback invocation cost, but overall scores in on the third place. +C performs admirably well, about on par with C, even +when using its pure perl backend. + C's memory usage is quite a bit higher, but it features a faster callback invocation and overall ends up in the same class as C. However, Glib scales extremely badly, doubling the number of @@ -1587,7 +2291,8 @@ connections, most of which are idle at any one point in time. Source code for this benchmark is found as F in the AnyEvent -distribution. +distribution. It uses the L interface, which makes a real difference +for the EV and Perl backends only. =head3 Explanation of the columns @@ -1604,12 +2309,14 @@ =head3 Results - name sockets create request - EV 20000 69.01 11.16 - Perl 20000 73.32 35.87 - Event 20000 212.62 257.32 - Glib 20000 651.16 1896.30 - POE 20000 349.67 12317.24 uses POE::Loop::Event + name sockets create request + EV 20000 62.66 7.99 + Perl 20000 68.32 32.64 + IOAsync 20000 174.06 101.15 epoll + IOAsync 20000 174.67 610.84 poll + Event 20000 202.69 242.91 + Glib 20000 557.01 1689.52 + POE 20000 341.54 12086.32 uses POE::Loop::Event =head3 Discussion @@ -1622,6 +2329,9 @@ Perl surprisingly comes second. It is much faster than the C-based event loops Event and Glib. +IO::Async performs very well when using its epoll backend, and still quite +good compared to Glib when using its pure perl backend. + Event suffers from high setup time as well (look at its code and you will understand why). Callback invocation also has a high overhead compared to the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event @@ -1693,15 +2403,210 @@ =back +=head2 THE IO::Lambda BENCHMARK + +Recently I was told about the benchmark in the IO::Lambda manpage, which +could be misinterpreted to make AnyEvent look bad. In fact, the benchmark +simply compares IO::Lambda with POE, and IO::Lambda looks better (which +shouldn't come as a surprise to anybody). As such, the benchmark is +fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't +very optimal. But how would AnyEvent compare when used without the extra +baggage? To explore this, I wrote the equivalent benchmark for AnyEvent. + +The benchmark itself creates an echo-server, and then, for 500 times, +connects to the echo server, sends a line, waits for the reply, and then +creates the next connection. This is a rather bad benchmark, as it doesn't +test the efficiency of the framework or much non-blocking I/O, but it is a +benchmark nevertheless. + + name runtime + Lambda/select 0.330 sec + + optimized 0.122 sec + Lambda/AnyEvent 0.327 sec + + optimized 0.138 sec + Raw sockets/select 0.077 sec + POE/select, components 0.662 sec + POE/select, raw sockets 0.226 sec + POE/select, optimized 0.404 sec + + AnyEvent/select/nb 0.085 sec + AnyEvent/EV/nb 0.068 sec + +state machine 0.134 sec + +The benchmark is also a bit unfair (my fault): the IO::Lambda/POE +benchmarks actually make blocking connects and use 100% blocking I/O, +defeating the purpose of an event-based solution. All of the newly +written AnyEvent benchmarks use 100% non-blocking connects (using +AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS +resolver), so AnyEvent is at a disadvantage here, as non-blocking connects +generally require a lot more bookkeeping and event handling than blocking +connects (which involve a single syscall only). + +The last AnyEvent benchmark additionally uses L, which +offers similar expressive power as POE and IO::Lambda, using conventional +Perl syntax. This means that both the echo server and the client are 100% +non-blocking, further placing it at a disadvantage. + +As you can see, the AnyEvent + EV combination even beats the +hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl +backend easily beats IO::Lambda and POE. + +And even the 100% non-blocking version written using the high-level (and +slow :) L abstraction beats both POE and IO::Lambda +higher level ("unoptimised") abstractions by a large margin, even though +it does all of DNS, tcp-connect and socket I/O in a non-blocking way. + +The two AnyEvent benchmarks programs can be found as F and +F in the AnyEvent distribution, the remaining benchmarks are +part of the IO::Lambda distribution and were used without any changes. + + +=head1 SIGNALS + +AnyEvent currently installs handlers for these signals: + +=over 4 + +=item SIGCHLD + +A handler for C is installed by AnyEvent's child watcher +emulation for event loops that do not support them natively. Also, some +event loops install a similar handler. + +Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then +AnyEvent will reset it to default, to avoid losing child exit statuses. + +=item SIGPIPE + +A no-op handler is installed for C when C<$SIG{PIPE}> is C +when AnyEvent gets loaded. + +The rationale for this is that AnyEvent users usually do not really depend +on SIGPIPE delivery (which is purely an optimisation for shell use, or +badly-written programs), but C can cause spurious and rare +program exits as a lot of people do not expect C when writing to +some random socket. + +The rationale for installing a no-op handler as opposed to ignoring it is +that this way, the handler will be restored to defaults on exec. + +Feel free to install your own handler, or reset it to defaults. + +=back + +=cut + +undef $SIG{CHLD} + if $SIG{CHLD} eq 'IGNORE'; + +$SIG{PIPE} = sub { } + unless defined $SIG{PIPE}; + +=head1 RECOMMENDED/OPTIONAL MODULES + +One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and +its built-in modules) are required to use it. + +That does not mean that AnyEvent won't take advantage of some additional +modules if they are installed. + +This section explains which additional modules will be used, and how they +affect AnyEvent's operation. + +=over 4 + +=item L + +This slightly arcane module is used to implement fast signal handling: To +my knowledge, there is no way to do completely race-free and quick +signal handling in pure perl. To ensure that signals still get +delivered, AnyEvent will start an interval timer to wake up perl (and +catch the signals) with some delay (default is 10 seconds, look for +C<$AnyEvent::MAX_SIGNAL_LATENCY>). + +If this module is available, then it will be used to implement signal +catching, which means that signals will not be delayed, and the event loop +will not be interrupted regularly, which is more efficient (and good for +battery life on laptops). + +This affects not just the pure-perl event loop, but also other event loops +that have no signal handling on their own (e.g. Glib, Tk, Qt). + +Some event loops (POE, Event, Event::Lib) offer signal watchers natively, +and either employ their own workarounds (POE) or use AnyEvent's workaround +(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L +does nothing for those backends. + +=item L + +This module isn't really "optional", as it is simply one of the backend +event loops that AnyEvent can use. However, it is simply the best event +loop available in terms of features, speed and stability: It supports +the AnyEvent API optimally, implements all the watcher types in XS, does +automatic timer adjustments even when no monotonic clock is available, +can take avdantage of advanced kernel interfaces such as C and +C, and is the fastest backend I. You can even embed +L/L in it (or vice versa, see L and L). + +If you only use backends that rely on another event loop (e.g. C), +then this module will do nothing for you. + +=item L + +The guard module, when used, will be used to implement +C. This speeds up guards considerably (and uses a +lot less memory), but otherwise doesn't affect guard operation much. It is +purely used for performance. + +=item L and L + +One of these modules is required when you want to read or write JSON data +via L. L is also written in pure-perl, but can take +advantage of the ultra-high-speed L module when it is installed. + +=item L + +Implementing TLS/SSL in Perl is certainly interesting, but not very +worthwhile: If this module is installed, then L (with +the help of L), gains the ability to do TLS/SSL. + +=item L + +This module is part of perl since release 5.008. It will be used when the +chosen event library does not come with a timing source of its own. The +pure-perl event loop (L) will additionally use it to +try to use a monotonic clock for timing stability. + +=back + =head1 FORK Most event libraries are not fork-safe. The ones who are usually are -because they rely on inefficient but fork-safe C or C calls +- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll +are usually badly thought-out hacks that are incompatible with fork in +one way or another. Only L is fully fork-aware and ensures that you +continue event-processing in both parent and child (or both, if you know +what you are doing). + +This means that, in general, you cannot fork and do event processing in +the child if the event library was initialised before the fork (which +usually happens when the first AnyEvent watcher is created, or the library +is loaded). If you have to fork, you must either do so I creating your first -watcher OR you must not use AnyEvent at all in the child. +watcher OR you must not use AnyEvent at all in the child OR you must do +something completely out of the scope of AnyEvent. + +The problem of doing event processing in the parent I the child +is much more complicated: even for backends that I fork-aware or +fork-safe, their behaviour is not usually what you want: fork clones all +watchers, that means all timers, I/O watchers etc. are active in both +parent and child, which is almost never what you want. USing C +to start worker children from some kind of manage rprocess is usually +preferred, because it is much easier and cleaner, at the expense of having +to have another binary. =head1 SECURITY CONSIDERATIONS @@ -1723,7 +2628,11 @@ Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can be used to probe what backend is used and gain other information (which is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and -$ENV{PERL_ANYEGENT_STRICT}. +$ENV{PERL_ANYEVENT_STRICT}. + +Note that AnyEvent will remove I environment variables starting with +C from C<%ENV> when it is loaded while taint mode is +enabled. =head1 BUGS @@ -1731,12 +2640,16 @@ Perl 5.8 has numerous memleaks that sometimes hit this module and are hard to work around. If you suffer from memleaks, first upgrade to Perl 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other annoying -mamleaks, such as leaking on C and C but it is usually not as +memleaks, such as leaking on C and C but it is usually not as pronounced). =head1 SEE ALSO +Tutorial/Introduction: L. + +FAQ: L. + Utility functions: L. Event modules: L, L, L, L, L, @@ -1745,16 +2658,17 @@ Implementations: L, L, L, L, L, L, L, -L. +L, L, L. Non-blocking file handles, sockets, TCP clients and -servers: L, L. +servers: L, L, L. Asynchronous DNS: L. -Coroutine support: L, L, L, L, +Thread support: L, L, L, L. -Nontrivial usage examples: L, L, L. +Nontrivial usage examples: L, L, +L. =head1 AUTHOR