--- AnyEvent/README 2010/04/28 14:15:55 1.61 +++ AnyEvent/README 2011/08/21 03:02:32 1.66 @@ -2,12 +2,12 @@ AnyEvent - the DBI of event loop programming EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, - Qt and POE are various supported event loops/environments. + Qt, FLTK and POE are various supported event loops/environments. SYNOPSIS use AnyEvent; - # if you prefer function calls, look at the L manpage for + # if you prefer function calls, look at the AE manpage for # an alternative API. # file handle or descriptor readable @@ -15,7 +15,7 @@ # one-shot or repeating timers my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); - my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... + 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. @@ -44,8 +44,10 @@ manpage. SUPPORT - There is a mailinglist for discussing all things AnyEvent, and an IRC - channel, too. + An FAQ document is available as AnyEvent::FAQ. + + There also is a mailinglist for discussing all things AnyEvent, and an + IRC channel, too. See the AnyEvent project page at the Schmorpforge Ta-Sa Software Repository, at , for more info. @@ -73,26 +75,26 @@ For modules like POE or IO::Async (which is a total misnomer as it is actually doing all I/O *synchronously*...), 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 *also* forced to use the same event loop you use. AnyEvent is different: 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. Again: if 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 - to AnyEvent, too, so it is future-proof). + with the rest: POE + EV? No go. Tk + Event? No go. Again: if 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 easy to add new event loops to + AnyEvent, too, so it is future-proof). In addition to being free of having to use *the one and only true event model*, 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 offering the functionality that is necessary, in as thin as a - wrapper as technically possible. + 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. Of course, AnyEvent comes with a big (and fully optional!) toolbox of useful functionality, such as an asynchronous DNS resolver, 100% @@ -105,24 +107,22 @@ model, you should *not* use this module. DESCRIPTION - AnyEvent 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). + AnyEvent 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 Event 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: EV, Event, Glib, - AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. 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: EV, AnyEvent::Loop, Event, Glib, + Tk, Event::Lib, Qt, POE. 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 EV is not available, the pure-perl + AnyEvent::Loop 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 @@ -134,12 +134,13 @@ # .. AnyEvent will likely default to Tk The *likely* 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... - - The pure-perl implementation of AnyEvent is called - "AnyEvent::Impl::Perl". Like other event modules you can load it - explicitly and enjoy the high availability of that event loop :) + 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 "AnyEvent::Loop". + Like other event modules you can load it explicitly and enjoy the high + availability of that event loop :) WATCHERS AnyEvent has the central concept of a *watcher*, which is an object that @@ -153,11 +154,11 @@ Note that callbacks must not permanently change global variables potentially in use by the event loop (such as $_ or $[) and that - callbacks must not "die". The former is good programming practise in + callbacks must not "die". 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 the watcher you have to destroy it (e.g. by setting the + To disable a watcher you have to destroy it (e.g. by setting the variable you store it in to "undef" or otherwise deleting all references to it). @@ -166,7 +167,7 @@ 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 @@ -207,7 +208,7 @@ it. 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. @@ -240,14 +241,14 @@ 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, "interval", as a strictly positive number (> 0), then the callback will be invoked regularly at that interval (in fractional seconds) after the first invocation. If "interval" 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 + attempt is made to avoid timer drift in most backends, so the interval is only approximate. Example: fire an event after 7.7 seconds. @@ -274,13 +275,13 @@ they 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 + supposed to 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 EV, which offers both relative - (ev_timer, based on true relative time) and absolute (ev_periodic, based - on wallclock time) timers. + conscious of these issues is EV, which offers both relative (ev_timer, + based on true relative time) and absolute (ev_periodic, based on + wallclock time) timers. AnyEvent always prefers relative timers, if available, matching the AnyEvent API. @@ -309,15 +310,15 @@ This function is also often faster then "AnyEvent->time", and thus the preferred method if you want some timestamp (for example, - AnyEvent::Handle uses this to update it's activity timeouts). + AnyEvent::Handle 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. + exact with your timing; you can skip it without a bad conscience. For a practical example of when these times differ, consider Event::Lib and EV and the following set-up: - The event loop is running and has just invoked one of your callback + 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 "sleep 1" (blocking the process for a second) and then (at time=501) you create a relative @@ -348,9 +349,9 @@ account. AnyEvent->now_update - Some event loops (such as EV or AnyEvent::Impl::Perl) cache the - current time for each loop iteration (see the discussion of - AnyEvent->now, above). + Some event loops (such as EV or AnyEvent::Loop) cache the current + time for each loop iteration (see the discussion of 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 @@ -416,7 +417,7 @@ 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 it's best, which means in some cases, signals + 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 $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable can be changed only before the first signal watcher is created, and @@ -428,15 +429,15 @@ All these problems can be avoided by installing the optional Async::Interrupt module, which works with most event loops. It will not work with inherently broken event loops such as Event or Event::Lib (and - not with POE currently, as POE does it's own workaround with one-second + not with POE currently, as POE does its own workaround with one-second latency). For those, you just have to suffer the delays. CHILD PROCESS WATCHERS $w = AnyEvent->child (pid => , cb => ); - You can also watch on a child process exit and catch its exit status. + You can also watch for a child process exit and catch its exit status. - The child process is specified by the "pid" argument (one some backends, + The child process is specified by the "pid" argument (on some backends, using 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 @@ -467,16 +468,16 @@ you "fork" the child (alternatively, you can call "AnyEvent::detect"). 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. + be emulated by AnyEvent in most cases, in which case the latency and + race problems mentioned in the description of signal watchers apply. Example: fork a process and wait for it my $done = AnyEvent->condvar; - - my $pid = fork or exit 5; - - my $w = AnyEvent->child ( + + my $pid = fork or exit 5; + + my $w = AnyEvent->child ( pid => $pid, cb => sub { my ($pid, $status) = @_; @@ -484,15 +485,15 @@ $done->send; }, ); - - # do something else, then wait for process exit + + # do something else, then wait for process exit $done->recv; IDLE WATCHERS $w = AnyEvent->idle (cb => ); - Repeatedly invoke the callback after the process becomes idle, until - either the watcher is destroyed or new events have been detected. + 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 @@ -541,8 +542,8 @@ 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. @@ -557,13 +558,27 @@ as if it were a callback, read about the caveats in the description for the "->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. And yet some people know them as "futures" - a - promise to compute/deliver something that you can wait for. + 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: + + * 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. + + * 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. + + * Condition variables are like "Merge Points" - points in your program + where you merge multiple independent results/control flows into one. + + * 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. + + * Condition variables represent future values, or promises to deliver + some result, long before the result is available. Condition variables are very useful to signal that something has finished, for example, if you write a module that does asynchronous http @@ -586,7 +601,7 @@ used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy (it is often useful to build your own transaction class on top of AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call - it's "new" method in your own "new" method. + its "new" method in your own "new" method. There are two "sides" to a condition variable - the "producer side" which eventually calls "-> send", and the "consumer side", which waits @@ -656,14 +671,14 @@ calling "send". $cv->croak ($error) - Similar to send, but causes all call's to "->recv" to invoke + Similar to send, but causes all calls to "->recv" to invoke "Carp::croak" with the given error message/object/scalar. This can be used to signal any errors to the condition variable user/consumer. Doing it this way instead of calling "croak" directly - delays the error detetcion, but has the overwhelmign advantage that + 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 clalback without connection to the actual + and not deep in some event callback with no connection to the actual code causing the problem. $cv->begin ([group callback]) @@ -710,7 +725,7 @@ 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 begung can potentially be zero: + that are begun can potentially be zero: my $cv = AnyEvent->condvar; @@ -741,7 +756,7 @@ (the loop doesn't execute once). This is the general pattern when you "fan out" into multiple (but - potentially none) subrequests: use an outer "begin"/"end" pair to + potentially zero) subrequests: use an outer "begin"/"end" pair to set the callback and ensure "end" is called at least once, and then, for each subrequest you start, call "begin" and for each subrequest you finish, call "end". @@ -752,7 +767,7 @@ $cv->recv Wait (blocking if necessary) until the "->send" or "->croak" methods - have been called on c<$cv>, while servicing other watchers normally. + have been called on $cv, while servicing other watchers normally. You can only wait once on a condition - additional calls are valid but will return immediately. @@ -779,7 +794,7 @@ the result will not block, while still supporting blocking waits if the caller so desires). - You can ensure that "-recv" never blocks by setting a callback and + You can ensure that "->recv" never blocks by setting a callback and only calling "->recv" from within that callback (or at a later time). This will work even when the event loop does not support blocking waits otherwise. @@ -792,11 +807,11 @@ 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 (or already - was) "true", i.e. when "send" or "croak" are called (or were - called), with the only argument being the condition variable itself. - Calling "recv" inside the callback or at any later time is - guaranteed not to block. + The callback will be called when the condition becomes "true", i.e. + when "send" or "croak" 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 "recv" inside + the callback or at any later time is guaranteed not to block. SUPPORTED EVENT LOOPS/BACKENDS The available backend classes are (every class has its own manpage): @@ -808,12 +823,12 @@ with AnyEvent itself. AnyEvent::Impl::EV based on EV (interface to libev, best choice). - AnyEvent::Impl::Perl pure-perl implementation, fast and portable. + AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable. Backends that are transparently being picked up when they are used. - These will be used when they are currently 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 + 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. @@ -824,6 +839,9 @@ AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 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. + AnyEvent::Impl::Cocoa based on Cocoa::EventLoop. + AnyEvent::Impl::FLTK2 based on FLTK (fltk 2 binding). Backends with special needs. Qt requires the Qt::Application to be instantiated first, but will @@ -833,14 +851,6 @@ AnyEvent::Impl::Qt based on Qt. - Support for IO::Async can only be partial, as it is too broken and - architecturally limited to even support the AnyEvent API. It also is - the only event loop that needs the loop to be set explicitly, so it - can only be used by a main program knowing about AnyEvent. See - AnyEvent::Impl::Async for the gory details. - - AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. - Event loops that are indirectly supported via other backends. Some event loops can be supported via other modules: @@ -868,7 +878,7 @@ 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 "AnyEvent::Impl:xxx" modules, but can be any + usually one of the "AnyEvent::Impl::xxx" modules, but can be any other class in the case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode* it will be "urxvt::anyevent"). @@ -876,14 +886,19 @@ Returns $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, and not e.g. while initialising of your module. + possible at runtime, and not e.g. during initialisation of your + module. + + The effect of calling this function is as if a watcher had been + created (specifically, actions that happen "when the first watcher + is created" happen when calling detetc as well). If you need to do some initialisation before AnyEvent watchers are created, use "post_detect". $guard = AnyEvent::post_detect { BLOCK } Arranges for the code block to be executed as soon as the event - model is autodetected (or immediately if this has already happened). + model is autodetected (or immediately if that has already happened). The block will be executed *after* the actual backend has been detected ($AnyEvent::MODEL is set), but *before* any watchers have @@ -902,7 +917,7 @@ AnyEvent::AIO for a case where this is useful. Example: Create a watcher for the IO::AIO module and store it in - $WATCHER. Only do so after the event loop is initialised, though. + $WATCHER, but do so only do so after the event loop is initialised. our WATCHER; @@ -919,7 +934,7 @@ @AnyEvent::post_detect If there are any code references in this array (you can "push" to it - before or after loading AnyEvent), then they will called directly + before or after loading AnyEvent), then they will be called directly after the event loop has been chosen. You should check $AnyEvent::MODEL before adding to this array, @@ -948,6 +963,57 @@ push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; } + AnyEvent::postpone { BLOCK } + Arranges for the block to be executed as soon as possible, but not + before the call itself returns. In practise, the block will be + executed just before the event loop polls for new events, or shortly + afterwards. + + This function never returns anything (to make the "return postpone { + ... }" idiom more useful. + + To understand the usefulness of this function, consider a function + that asynchronously does something for you and returns some + transaction object or guard to let you cancel the operation. For + example, "AnyEvent::Socket::tcp_connect": + + # start a conenction attempt unless one is active + $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub { + delete $self->{connect_guard}; + ... + }; + + Imagine that this function could instantly call the callback, for + example, because it detects an obvious error such as a negative port + number. Invoking the callback before the function returns causes + problems however: the callback will be called and will try to delete + the guard object. But since the function hasn't returned yet, there + is nothing to delete. When the function eventually returns it will + assign the guard object to "$self->{connect_guard}", where it will + likely never be deleted, so the program thinks it is still trying to + connect. + + This is where "AnyEvent::postpone" should be used. Instead of + calling the callback directly on error: + + $cb->(undef), return # signal error to callback, BAD! + if $some_error_condition; + + It should use "postpone": + + AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later + if $some_error_condition; + + AnyEvent::log $level, $msg[, @args] + Log the given $msg at the given $level. + + Loads AnyEvent::Log on first use and calls "AnyEvent::Log::log" - + consequently, look at the AnyEvent::Log documentation for details. + + If you want to sprinkle loads of logging calls around your code, + consider creating a logger callback with the "AnyEvent::Log::logger" + function. + 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. @@ -964,17 +1030,18 @@ It is fine, however, to call "->recv" when the user of your module requests it (i.e. if you create a http request object ad have a method - called "results" that returns the results, it should call "->recv" - freely, as the user of your module knows what she is doing. always). + called "results" that returns the results, it may call "->recv" freely, + as the user of your module knows what she is doing. Always). 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 "use AnyEvent". 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 @@ -982,12 +1049,12 @@ generally 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 + and it might choose the wrong one unless you load the correct one yourself. You can chose to use a pure-perl implementation by loading the - "AnyEvent::Impl::Perl" module, which gives you similar behaviour - everywhere, but letting AnyEvent chose the model is generally better. + "AnyEvent::Loop" module, which gives you similar behaviour everywhere, + but letting AnyEvent chose the model is generally better. MAINLOOP EMULATION Sometimes (often for short test scripts, or even standalone programs who @@ -1009,12 +1076,14 @@ The following is a non-exhaustive list of additional modules that use 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 with AnyEvent, most are available via CPAN. + modules come as part of AnyEvent, the others are available via CPAN (see + for a longer + non-exhaustive list), and the list is heavily biased towards modules of + the AnyEvent author himself :) AnyEvent::Util - Contains various utility functions that replace often-used but - blocking functions such as "inet_aton" by event-/callback-based - versions. + Contains various utility functions that replace often-used blocking + functions such as "inet_aton" with event/callback-based versions. AnyEvent::Socket Provides various utility functions for (internet protocol) sockets, @@ -1025,55 +1094,49 @@ AnyEvent::Handle 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 (via AnyEvent::TLS. + transparent and non-blocking SSL/TLS (via AnyEvent::TLS). AnyEvent::DNS Provides rich asynchronous DNS resolver capabilities. - AnyEvent::HTTP - A simple-to-use HTTP library that is capable of making a lot of - concurrent HTTP requests. - - AnyEvent::HTTPD - Provides a simple web application server framework. - - AnyEvent::FastPing - The fastest ping in the west. + AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, + AnyEvent::IGS, AnyEvent::FCP + 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). + + AnyEvent::Handle::UDP + 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. AnyEvent::DBI - Executes DBI requests asynchronously in a proxy process. + Executes DBI requests asynchronously in a proxy process for you, + notifying you in an event-based way when the operation is finished. AnyEvent::AIO - Truly asynchronous I/O, should be in the toolbox of every event - programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent - together. - - AnyEvent::BDB - Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently - fuses BDB and AnyEvent together. - - AnyEvent::GPSD - A non-blocking interface to gpsd, a daemon delivering GPS - information. - - AnyEvent::IRC - AnyEvent based IRC client module family (replacing the older - Net::IRC3). - - AnyEvent::XMPP - AnyEvent based XMPP (Jabber protocol) module family (replacing the - older Net::XMPP2>. - - AnyEvent::IGS - A non-blocking interface to the Internet Go Server protocol (used by - App::IGS). - - Net::FCP - AnyEvent-based implementation of the Freenet Client Protocol, - birthplace of AnyEvent. + Truly asynchronous (as opposed to non-blocking) I/O, should be in + the toolbox of every event programmer. AnyEvent::AIO transparently + fuses IO::AIO and AnyEvent together, giving AnyEvent access to + event-based file I/O, and much more. + + AnyEvent::HTTPD + A simple embedded webserver. - Event::ExecFlow - High level API for event-based execution flow control. + AnyEvent::FastPing + The fastest ping in the west. Coro Has special support for AnyEvent via Coro::AnyEvent. @@ -1114,11 +1177,11 @@ conditions. You can set this environment variable to make AnyEvent more talkative. - When set to 1 or higher, causes AnyEvent to warn about unexpected + When set to 5 or higher, causes AnyEvent to warn about unexpected conditions, such as not being able to load the event model specified by "PERL_ANYEVENT_MODEL". - When set to 2 or higher, cause AnyEvent to report to STDERR which + When set to 7 or higher, cause AnyEvent to report to STDERR which event model it chooses. When set to 8 or higher, then AnyEvent will report extra information @@ -1134,22 +1197,48 @@ In other words, enables "strict" mode. - Unlike "use strict" (or it's modern cousin, "use common::sense", it + Unlike "use strict" (or its modern cousin, "use common::sense", it is definitely recommended to keep it off in production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment while developing programs can be very useful, however. + "PERL_ANYEVENT_DEBUG_SHELL" + If this env variable is set, then its contents will be interpreted + by "AnyEvent::Socket::parse_hostport" (after replacing every + occurance of $$ by the process pid) and an "AnyEvent::Debug::shell" + is bound on that port. The shell object is saved in + $AnyEvent::Debug::SHELL. + + This takes place when the first watcher is created. + + For example, to bind a debug shell on a unix domain socket in + /tmp/debug.sock, you could use this: + + PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog + + Note that creating sockets in /tmp is very unsafe on multiuser + systems. + + "PERL_ANYEVENT_DEBUG_WRAP" + Can be set to 0, 1 or 2 and enables wrapping of all watchers for + debugging purposes. See "AnyEvent::Debug::wrap" for details. + "PERL_ANYEVENT_MODEL" This can be used to specify the event model to be used by AnyEvent, - before auto detection and -probing kicks in. It must be a string - consisting entirely of ASCII letters. The string "AnyEvent::Impl::" - gets prepended and the resulting module name is loaded and if the - load was successful, used as event model. If it fails to load - AnyEvent will proceed with auto detection and -probing. + before auto detection and -probing kicks in. - This functionality might change in future versions. + It normally is a string consisting entirely of ASCII letters (e.g. + "EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and + the resulting module name is loaded and - if the load was successful + - used as event model backend. If it fails to load then AnyEvent + will proceed with auto detection and -probing. + + If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::") + then nothing gets prepended and the module name is used as-is (hint: + "::" at the end of a string designates a module name and quotes it + appropriately). - For example, to force the pure perl model (AnyEvent::Impl::Perl) you + For example, to force the pure perl model (AnyEvent::Loop::Perl) you could start your program like this: PERL_ANYEVENT_MODEL=Perl perl ... @@ -1532,7 +1621,7 @@ * The overhead AnyEvent adds is usually much smaller than the overhead of the actual event loop, only with extremely fast event loops such - as EV adds AnyEvent significant overhead. + as EV does AnyEvent add significant overhead. * You should avoid POE like the plague if you want performance or reasonable memory usage. @@ -1740,7 +1829,7 @@ RECOMMENDED/OPTIONAL MODULES One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and - it's built-in modules) are required to use it. + 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. @@ -1801,10 +1890,9 @@ Time::HiRes 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 on - it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will - additionally use it to try to use a monotonic clock for timing - stability. + when the chosen event library does not come with a timing source of + its own. The pure-perl event loop (AnyEvent::Loop) will additionally + load it to try to use a monotonic clock for timing stability. FORK Most event libraries are not fork-safe. The ones who are usually are @@ -1845,8 +1933,8 @@ before the first watcher gets created, e.g. with a "BEGIN" block: BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } - - use AnyEvent; + + use AnyEvent; Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can be used to probe what backend is used and gain other information (which @@ -1865,24 +1953,32 @@ not as pronounced). SEE ALSO - Utility functions: AnyEvent::Util. + Tutorial/Introduction: AnyEvent::Intro. + + FAQ: AnyEvent::FAQ. + + Utility functions: AnyEvent::Util (misc. grab-bag), AnyEvent::Log + (simply logging). + + Development/Debugging: AnyEvent::Strict (stricter checking), + AnyEvent::Debug (interactive shell, watcher tracing). - Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, - Event::Lib, Qt, POE. + Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event, + Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK. Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, - AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. + AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi, AnyEvent::Impl::FLTK. - Non-blocking file handles, sockets, TCP clients and servers: + Non-blocking handles, pipes, stream sockets, TCP clients and servers: AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. Asynchronous DNS: AnyEvent::DNS. - Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, + Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. - Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, + Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, AnyEvent::HTTP. AUTHOR