--- AnyEvent/README 2009/06/29 21:00:32 1.42 +++ AnyEvent/README 2009/08/09 16:05:11 1.51 @@ -1,8 +1,8 @@ NAME - AnyEvent - provide framework for multiple event loops + AnyEvent - the DBI of event loop programming - EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are 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. SYNOPSIS use AnyEvent; @@ -40,6 +40,13 @@ tutorial or some gentle introduction, have a look at the AnyEvent::Intro manpage. +SUPPORT + There 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. + WHY YOU SHOULD USE THIS MODULE (OR NOT) Glib, POE, IO::Async, Event... CPAN offers event models by the dozen nowadays. So what is different about AnyEvent? @@ -168,10 +175,16 @@ declared. I/O WATCHERS + $w = AnyEvent->io ( + fh => , + poll => <"r" or "w">, + cb => , + ); + You can create an I/O watcher by calling the "AnyEvent->io" method with the following mandatory key-value pairs as arguments: - "fh" is the Perl *file handle* (*not* file descriptor) to watch for + "fh" is the Perl *file handle* (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, @@ -205,6 +218,14 @@ }); TIME WATCHERS + $w = AnyEvent->timer (after => , cb => ); + + $w = AnyEvent->timer ( + after => , + interval => , + cb => , + ); + You can create a time watcher by calling the "AnyEvent->timer" method with the following mandatory arguments: @@ -338,6 +359,8 @@ Note that updating the time *might* cause some events to be handled. SIGNAL WATCHERS + $w = AnyEvent->signal (signal => , cb => ); + You can watch for signals using a signal watcher, "signal" is the signal *name* in uppercase and without any "SIG" prefix, "cb" is the Perl callback to be invoked whenever a signal occurs. @@ -352,22 +375,46 @@ process, 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. + signal between multiple watchers, and AnyEvent will ensure that signals + will not interrupt your program at bad times. - This watcher might use %SIG, so programs overwriting those signals - directly will likely not work correctly. + This watcher might use %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 }); + 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 it's 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 + 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 + 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 + 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. - The child process is specified by the "pid" argument (if set to 0, it - watches for any child process exit). The watcher will triggered only - when the child process has finished and an exit status is available, not - on any trace events (stopped/continued). + The child process is specified by the "pid" argument (one 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 + (stopped/continued). The callback will be called with the pid and exit status (as returned by waitpid), so unlike other watcher types, you *can* rely on child watcher @@ -393,6 +440,10 @@ an AnyEvent program, you *have* to create at least one watcher before 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. + Example: fork a process and wait for it my $done = AnyEvent->condvar; @@ -412,6 +463,8 @@ $done->recv; IDLE WATCHERS + $w = AnyEvent->idle (cb => ); + Sometimes there is a need to do something, but it is not so important to do it instantly, but only when there is nothing better to do. This "nothing better to do" is usually defined to be "no other events need @@ -446,19 +499,26 @@ }); 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. + Now is probably a good time to look at the examples further below. + Condition variables can be created by calling the "AnyEvent->condvar" method, usually without arguments. The only argument pair allowed is - "cb", which specifies a callback to be called when the condition variable becomes true, with the condition variable as the first argument (but not the results). @@ -473,7 +533,8 @@ 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. + delivers a result. And yet some people know them as "futures" - a + promise to compute/deliver something that you can wait for. Condition variables are very useful to signal that something has finished, for example, if you write a module that does asynchronous http @@ -517,11 +578,11 @@ ); # this "blocks" (while handling events) till the callback - # calls send + # calls -recv; Example: wait for a timer, but take advantage of the fact that condition - variables are also code references. + variables are also callable directly. my $done = AnyEvent->condvar; my $delay = AnyEvent->timer (after => 5, cb => $done); @@ -537,7 +598,7 @@ my @info = $couchdb->info->recv; - And this is how you would just ste a callback to be called whenever the + And this is how you would just set a callback to be called whenever the results are available: $couchdb->info->cb (sub { @@ -562,20 +623,19 @@ future "->recv" calls. Condition variables are overloaded so one can call them directly (as - a code reference). Calling them directly is the same as calling - "send". 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 AnyEvent::Socket and - AnyEvent::DNS for example). + if they were a code reference). Calling them directly is the same as + calling "send". $cv->croak ($error) Similar to send, but causes all call's 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. + user/consumer. Doing it this way instead of calling "croak" directly + delays the error detetcion, but has the overwhelmign 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 + code causing the problem. $cv->begin ([group callback]) $cv->end @@ -673,25 +733,21 @@ In list context, all parameters passed to "send" 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 "->recv" + is not allowed, and the "recv" call will "croak" if such a condition + is detected. This condition can be slightly loosened by using + Coro::AnyEvent, which allows you to do a blocking "->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 *if you are - using this from a module, never require a blocking wait*, but 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 *never* to "->recv" in a module is that you cannot - sensibly have two "->recv"'s in parallel, as that would require - multiple interpreters or coroutines/threads, none of which - "AnyEvent" can supply. - - The Coro module, however, *can* and *does* supply coroutines and, in - fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe - versions and also integrates coroutines into AnyEvent, making - blocking "->recv" calls perfectly safe as long as they are done from - another coroutine (one that doesn't run the event loop). + 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). You can ensure that "-recv" never blocks by setting a callback and only calling "->recv" from within that callback (or at a later @@ -706,57 +762,130 @@ 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 "send" or "croak" are 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. - -GLOBAL VARIABLES AND FUNCTIONS - $AnyEvent::MODEL - Contains "undef" 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 "AnyEvent::Impl:xxx" modules, but can be any other class in the - case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). - - The known classes so far are: + 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. + +SUPPORTED EVENT LOOPS/BACKENDS + The available backend classes are (every class has its own manpage): + + Backends that are autoprobed when no other event loop can be found. + 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). + + 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 + 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. + + 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. + + 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: - # warning, support for IO::Async is only partial, as it is too broken - # and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async. - AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs). - - 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. + There is no direct support for WxWidgets (Wx) or Prima. - AnyEvent knows about Prima and Wx and will try to use POE when - autodetecting them. + 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. + + Prima 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 Prima and Wx, however, and will try to + load POE when detecting them, in the hope that POE will pick them + up, in which case everything will be automatic. + +GLOBAL VARIABLES AND FUNCTIONS + These are not normally required to use AnyEvent, but can be useful to + write AnyEvent extension modules. + + $AnyEvent::MODEL + Contains "undef" 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 "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"). AnyEvent::detect 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. + possible at runtime, and not e.g. while initialising of your module. + + If you need to do some initialisation before AnyEvent watchers are + created, use "post_detect". $guard = AnyEvent::post_detect { BLOCK } Arranges for the code block to be executed as soon as the event model is autodetected (or immediately if this has already happened). + The block will be executed *after* the actual backend has been + detected ($AnyEvent::MODEL is set), but *before* any watchers have + been created, so it is possible to e.g. patch @AnyEvent::ISA or do + other initialisations - see the sources of AnyEvent::Strict or + AnyEvent::AIO 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, AnyEvent::AIO + creates and installs the global IO::AIO watcher in a "post_detect" + 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 Coro::BDB for a case where this is useful. + destroyed (or "undef" when the hook was immediately executed). See + 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. + + 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; @AnyEvent::post_detect If there are any code references in this array (you can "push" to it @@ -764,10 +893,17 @@ after the event loop has been chosen. You should check $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. + though: if it is defined then the event loop has already been + detected, and the array will be ignored. - Best use "AnyEvent::post_detect { BLOCK }" instead. + Best use "AnyEvent::post_detect { BLOCK }" 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. WHAT TO DO IN A MODULE As a module author, you should "use AnyEvent" and call AnyEvent methods @@ -828,9 +964,9 @@ 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 with AnyEvent, most are available via CPAN. AnyEvent::Util Contains various utility functions that replace often-used but @@ -846,7 +982,7 @@ 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. + transparent and non-blocking SSL/TLS (via AnyEvent::TLS. AnyEvent::DNS Provides rich asynchronous DNS resolver capabilities. @@ -877,16 +1013,17 @@ A non-blocking interface to gpsd, a daemon delivering GPS information. - AnyEvent::IGS - A non-blocking interface to the Internet Go Server protocol (used by - App::IGS). - AnyEvent::IRC AnyEvent based IRC client module family (replacing the older Net::IRC3). - Net::XMPP2 - AnyEvent based XMPP (Jabber protocol) module family. + 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, @@ -898,9 +1035,12 @@ Coro Has special support for AnyEvent via Coro::AnyEvent. - IO::Lambda - The lambda approach to I/O - don't ask, look there. Can use - AnyEvent. +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. + + See the AE manpage for details. ERROR AND EXCEPTION HANDLING In general, AnyEvent does not do any error handling - it relies on the @@ -938,6 +1078,10 @@ When set to 2 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 + on which optional modules it loads and how it implements certain + features. + "PERL_ANYEVENT_STRICT" AnyEvent does not do much argument checking by default, as thorough argument checking is very costly. Setting this variable to a true @@ -947,9 +1091,10 @@ In other words, enables "strict" mode. - Unlike "use strict", 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. + Unlike "use strict" (or it's 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_MODEL" This can be used to specify the event model to be used by AnyEvent, @@ -1001,6 +1146,26 @@ The maximum number of child processes that "AnyEvent::Util::fork_call" will create in parallel. + "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" + The default value for the "max_outstanding" parameter for the + default DNS resolver - this is the maximum number of parallel DNS + requests that are sent to the DNS server. + + "PERL_ANYEVENT_RESOLV_CONF" + The file to use instead of /etc/resolv.conf (or OS-specific + configuration) in the default resolver. When set to the empty + string, no default config will be used. + + "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". + When neither "ca_file" nor "ca_path" was specified during + AnyEvent::TLS context creation, and either of these environment + variables exist, they will be used to specify CA certificate + locations instead of a system-dependent default. + + "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" + When these are set to 1, then the respective modules are not loaded. + Mostly good for testing AnyEvent itself. + 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 @@ -1210,7 +1375,8 @@ which it is), lets them fire exactly once and destroys them again. Source code for this benchmark is found as eg/bench in the AnyEvent - distribution. + distribution. It uses the AE interface, which makes a real difference + for the EV and Perl backends only. Explanation of the columns *watcher* is the number of event watchers created/destroyed. Since @@ -1239,18 +1405,18 @@ Results name watchers bytes create invoke destroy comment - EV/EV 400000 224 0.47 0.35 0.27 EV native interface - EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers - CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal - Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation - Event/Event 16000 517 32.20 31.80 0.81 Event native interface - Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers - IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll - IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll - Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour - Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers - POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event - POE/Select 2000 6027 94.54 809.13 579.80 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 Discussion The benchmark does *not* measure scalability of the event loop very @@ -1271,9 +1437,10 @@ CPU cycles with POE. "EV" 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 AE 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 @@ -1353,7 +1520,8 @@ many connections, most of which are idle at any one point in time. Source code for this benchmark is found as eg/bench2 in the AnyEvent - distribution. + distribution. It uses the AE interface, which makes a real difference + for the EV and Perl backends only. Explanation of the columns *sockets* is the number of sockets, and twice the number of "servers" @@ -1369,13 +1537,13 @@ Results name sockets create request - EV 20000 69.01 11.16 - Perl 20000 73.32 35.87 - IOAsync 20000 157.00 98.14 epoll - IOAsync 20000 159.31 616.06 poll - Event 20000 212.62 257.32 - Glib 20000 651.16 1896.30 - POE 20000 349.67 12317.24 uses POE::Loop::Event + 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 Discussion This benchmark *does* measure scalability and overall performance of the @@ -1514,8 +1682,9 @@ emulation for event loops that do not support them natively. Also, some event loops install a similar handler. - If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent - will reset it to default, to avoid losing child exit statuses. + Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, + then AnyEvent will reset it to default, to avoid losing child exit + statuses. SIGPIPE A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is @@ -1533,13 +1702,82 @@ Feel free to install your own handler, or reset it to defaults. +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. + + That does not mean that AnyEvent won't take advantage of some additional + modules if they are installed. + + This section epxlains which additional modules will be used, and how + they affect AnyEvent's operetion. + + Async::Interrupt + 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 $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 $AnyEvent::MAX_SIGNAL_LATENCY). + Installing Async::Interrupt does nothing for those backends. + + EV 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 "epoll" and "kqueue", and is the fastest backend *by far*. + You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and + Glib::EV). + + Guard + The guard module, when used, will be used to implement + "AnyEvent::Util::guard". 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. + + JSON and JSON::XS + This module is required when you want to read or write JSON data via + AnyEvent::Handle. It is also written in pure-perl, but can take + advantage of the ultra-high-speed JSON::XS module when it is + installed. + + In fact, AnyEvent::Handle will use JSON::XS by default if it is + installed. + + Net::SSLeay + Implementing TLS/SSL in Perl is certainly interesting, but not very + worthwhile: If this module is installed, then AnyEvent::Handle (with + the help of AnyEvent::TLS), gains the ability to do TLS/SSL. + + 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. + FORK Most event libraries are not fork-safe. The ones who are usually are because they rely on inefficient but fork-safe "select" or "poll" calls. Only EV is fully fork-aware. If you have to fork, you must either do so *before* 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. SECURITY CONSIDERATIONS AnyEvent can be forced to load any event model via @@ -1580,16 +1818,18 @@ 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::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, + AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. Non-blocking file handles, sockets, TCP clients and servers: - AnyEvent::Handle, AnyEvent::Socket. + AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. Asynchronous DNS: AnyEvent::DNS. Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, - Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. + Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, + AnyEvent::HTTP. AUTHOR Marc Lehmann