--- AnyEvent/README 2011/08/26 05:33:53 1.67 +++ AnyEvent/README 2013/08/21 08:40:28 1.71 @@ -264,7 +264,7 @@ my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { warn "timeout\n"; - }; + }); TIMING ISSUES There are two ways to handle timers: based on real time (relative, "fire @@ -405,8 +405,8 @@ 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. + "unsafe" (asynchronous) - the former might delay signal delivery + 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 @@ -418,19 +418,15 @@ 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 $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. + will be delayed. The maximum time a signal might be delayed is 10 + seconds by default, but can be overriden via + $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} or $AnyEvent::MAX_SIGNAL_LATENCY + - see the "ENVIRONMENT VARIABLES" section for details. 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 its own workaround with one-second - latency). For those, you just have to suffer the delays. + not with POE currently). For those, you just have to suffer the delays. CHILD PROCESS WATCHERS $w = AnyEvent->child (pid => , cb => ); @@ -742,6 +738,10 @@ $cv->end; + ... + + my $results = $cv->recv; + This code fragment supposedly pings a number of hosts and calls "send" after results for all then have have been gathered - in any order. To achieve this, the code issues a call to "begin" when it @@ -780,10 +780,15 @@ 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. + is not allowed and the "recv" call will "croak" if such a condition + is detected. This requirement can be dropped by relying on + Coro::AnyEvent , which allows you to do a blocking "->recv" from any + thread that doesn't run the event loop itself. Coro::AnyEvent is + loaded automatically when Coro is used with AnyEvent, so code does + not need to do anything special to take advantage of that: any code + that would normally block your program because it calls "recv", be + executed in an "async" thread instead without blocking other + threads. 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 @@ -841,7 +846,7 @@ 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). + AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding). Backends with special needs. Qt requires the Qt::Application to be instantiated first, but will @@ -1012,7 +1017,9 @@ it will load AnyEvent::Log and call "AnyEvent::Log::log" - consequently, look at the AnyEvent::Log documentation for details. - If the test fails it will simply return. + If the test fails it will simply return. Right now this happens when + a numerical loglevel is used and it is larger than the level + specified via $ENV{PERL_ANYEVENT_VERBOSE}. If you want to sprinkle loads of logging calls around your code, consider creating a logger callback with the "AnyEvent::Log::logger" @@ -1086,22 +1093,22 @@ non-exhaustive list), and the list is heavily biased towards modules of the AnyEvent author himself :) - AnyEvent::Util + AnyEvent::Util (part of the AnyEvent distribution) Contains various utility functions that replace often-used blocking functions such as "inet_aton" with event/callback-based versions. - AnyEvent::Socket + AnyEvent::Socket (part of the AnyEvent distribution) Provides various utility functions for (internet protocol) sockets, addresses and name resolution. Also functions to create non-blocking tcp connections or tcp servers, with IPv6 and SRV record support and more. - AnyEvent::Handle + AnyEvent::Handle (part of the AnyEvent distribution) 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). - AnyEvent::DNS + AnyEvent::DNS (part of the AnyEvent distribution) Provides rich asynchronous DNS resolver capabilities. AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, @@ -1110,7 +1117,7 @@ (for the curious, IGS is the International Go Server and FCP is the Freenet Client Protocol). - AnyEvent::AIO + AnyEvent::AIO (part of the AnyEvent distribution) 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 @@ -1218,19 +1225,24 @@ The following environment variables are currently known to AnyEvent: "PERL_ANYEVENT_VERBOSE" - By default, AnyEvent will be completely silent except in fatal - conditions. You can set this environment variable to make AnyEvent - more talkative. If you want to do more than just set the global - logging level you should have a look at "PERL_ANYEVENT_LOG", which - allows much more complex specifications. - - When set to 5 or higher (warn), causes AnyEvent to warn about - unexpected conditions, such as not being able to load the event - model specified by "PERL_ANYEVENT_MODEL", or a guard callback - throwing an exception - this is the minimum recommended level. + By default, AnyEvent will log messages with loglevel 4 ("error") or + higher (see AnyEvent::Log). You can set this environment variable to + a numerical loglevel to make AnyEvent more (or less) talkative. + + If you want to do more than just set the global logging level you + should have a look at "PERL_ANYEVENT_LOG", which allows much more + complex specifications. + + When set to 0 ("off"), then no messages whatsoever will be logged + with everything else at defaults. + + When set to 5 or higher ("warn"), AnyEvent warns about unexpected + conditions, such as not being able to load the event model specified + by "PERL_ANYEVENT_MODEL", or a guard callback throwing an exception + - this is the minimum recommended level for use during development. - When set to 7 or higher (info), cause AnyEvent to report which event - model it chooses. + When set to 7 or higher (info), AnyEvent reports which event model + it chooses. When set to 8 or higher (debug), then AnyEvent will report extra information on which optional modules it loads and how it implements @@ -1252,7 +1264,8 @@ Note that specifying this environment variable causes the AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE" does not, so only using the latter saves a few hundred kB of memory - until the first message is being logged. + unless a module explicitly needs the extra features of + AnyEvent::Log. "PERL_ANYEVENT_STRICT" AnyEvent does not do much argument checking by default, as thorough @@ -1269,10 +1282,10 @@ 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 $$ by the process pid) and an "AnyEvent::Debug::shell" - is bound on that port. The shell object is saved in + If this env variable is nonempty, then its contents will be + interpreted by "AnyEvent::Socket::parse_hostport" and + "AnyEvent::Debug::shell" (after replacing every occurance of $$ by + the process pid). The shell object is saved in $AnyEvent::Debug::SHELL. This happens when the first watcher is created. @@ -1281,9 +1294,15 @@ /tmp/debug.sock, you could use this: PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog + # connect with e.g.: socat readline /tmp/debug123.sock - Note that creating sockets in /tmp is very unsafe on multiuser - systems. + Or to bind to tcp port 4545 on localhost: + + PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog + # connect with e.g.: telnet localhost 4545 + + Note that creating sockets in /tmp or on localhost 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 @@ -1309,6 +1328,13 @@ PERL_ANYEVENT_MODEL=Perl perl ... + "PERL_ANYEVENT_IO_MODEL" + The current file I/O model - see AnyEvent::IO for more info. + + At the moment, only "Perl" (small, pure-perl, synchronous) and + "IOAIO" (truly asynchronous) are supported. The default is "IOAIO" + if AnyEvent::AIO can be loaded, otherwise it is "Perl". + "PERL_ANYEVENT_PROTOCOLS" Used by both AnyEvent::DNS and AnyEvent::Socket to determine preferences for IPv4 or IPv6. The default is unspecified (and might @@ -1354,6 +1380,27 @@ default DNS resolver - this is the maximum number of parallel DNS requests that are sent to the DNS server. + "PERL_ANYEVENT_MAX_SIGNAL_LATENCY" + Perl has inherently racy signal handling (you can basically choose + between losing signals and memory corruption) - pure perl event + loops (including "AnyEvent::Loop", when "Async::Interrupt" isn't + available) therefore have to poll regularly to avoid losing signals. + + Some event loops are racy, but don't poll regularly, and some event + loops are written in C but are still racy. For those event loops, + AnyEvent installs a timer that regularly wakes up the event loop. + + By default, the interval for this timer is 10 seconds, but you can + override this delay with this environment variable (or by setting + the $AnyEvent::MAX_SIGNAL_LATENCY variable before creating signal + watchers). + + Lower values increase CPU (and energy) usage, higher values can + introduce long delays when reaping children or waiting for signals. + + The AnyEvent::Async module, if available, will be used to avoid this + polling (with most event loops). + "PERL_ANYEVENT_RESOLV_CONF" The absolute path to a resolv.conf-style file to use instead of /etc/resolv.conf (or the OS-specific configuration) in the default @@ -1965,6 +2012,15 @@ its own. The pure-perl event loop (AnyEvent::Loop) will additionally load it to try to use a monotonic clock for timing stability. + AnyEvent::AIO (and IO::AIO) + The default implementation of AnyEvent::IO is to do I/O + synchronously, stopping programs while they access the disk, which + is fine for a lot of programs. + + Installing AnyEvent::AIO (and its IO::AIO dependency) makes it + switch to a true asynchronous implementation, so event processing + can continue even while waiting for disk I/O. + 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 @@ -2045,6 +2101,8 @@ Non-blocking handles, pipes, stream sockets, TCP clients and servers: AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. + Asynchronous File I/O: AnyEvent::IO. + Asynchronous DNS: AnyEvent::DNS. Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. @@ -2054,5 +2112,5 @@ AUTHOR Marc Lehmann - http://home.schmorp.de/ + http://anyevent.schmorp.de