--- AnyEvent/README 2013/08/21 08:40:28 1.71 +++ AnyEvent/README 2016/09/17 02:33:54 1.77 @@ -1,8 +1,9 @@ NAME AnyEvent - the DBI of event loop programming - EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, - Qt, FLTK and POE are various supported event loops/environments. + EV, Event, Glib, Tk, UV, Perl, Event::Lib, Irssi, rxvt-unicode, + IO::Async, Qt, FLTK and POE are various supported event + loops/environments. SYNOPSIS use AnyEvent; @@ -471,6 +472,10 @@ my $done = AnyEvent->condvar; + # this forks and immediately calls exit in the child. this + # normally has all sorts of bad consequences for your parent, + # so take this as an example only. always fork and exec, + # or call POSIX::_exit, in real code. my $pid = fork or exit 5; my $w = AnyEvent->child ( @@ -720,7 +725,7 @@ "end" 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 + the there are results to be passed back, and the number of tasks that are begun can potentially be zero: my $cv = AnyEvent->condvar; @@ -809,8 +814,8 @@ "croak" have been called. $cb = $cv->cb ($cb->($cv)) - This is a mutator function that returns the callback set and - optionally replaces it before doing so. + This is a mutator function that returns the callback set (or "undef" + if not) 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 @@ -818,6 +823,10 @@ callback is called immediately when it is set. Calling "recv" inside the callback or at any later time is guaranteed not to block. + Additionally, when the callback is invoked, it is also removed from + the condvar (reset to "undef"), so the condvar does not keep a + reference to the callback after invocation. + SUPPORTED EVENT LOOPS/BACKENDS The available backend classes are (every class has its own manpage): @@ -841,6 +850,7 @@ 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::UV based on UV, innovated square wheels. 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. @@ -982,7 +992,7 @@ transaction object or guard to let you cancel the operation. For example, "AnyEvent::Socket::tcp_connect": - # start a conenction attempt unless one is active + # start a connection attempt unless one is active $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub { delete $self->{connect_guard}; ... @@ -1026,6 +1036,10 @@ function, which can reduce typing, codesize and can reduce the logging overhead enourmously. + AnyEvent::fh_block $filehandle + AnyEvent::fh_unblock $filehandle + Sets blocking or non-blocking behaviour for the given filehandle. + 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. @@ -1123,6 +1137,18 @@ fuses IO::AIO and AnyEvent together, giving AnyEvent access to event-based file I/O, and much more. + AnyEvent::Fork, AnyEvent::Fork::RPC, AnyEvent::Fork::Pool, + AnyEvent::Fork::Remote + These let you safely fork new subprocesses, either locally or + remotely (e.g.v ia ssh), using some RPC protocol or not, without the + limitations normally imposed by fork (AnyEvent works fine for + example). Dynamically-resized worker pools are obviously included as + well. + + And they are quite tiny and fast as well - "abusing" AnyEvent::Fork + just to exec external programs can easily beat using "fork" and + "exec" (or even "system") in most programs. + AnyEvent::Filesys::Notify AnyEvent is good for non-blocking stuff, but it can't detect file or path changes (e.g. "watch this directory for new files", "watch this @@ -1133,16 +1159,13 @@ transparently on other platforms, so it's about as portable as it gets. - (I haven't used it myself, but I haven't heard anybody complaining - about it yet). + (I haven't used it myself, but it seems the biggest problem with it + is it quite bad performance). AnyEvent::DBI Executes DBI requests asynchronously in a proxy process for you, notifying you in an event-based way when the operation is finished. - AnyEvent::HTTPD - A simple embedded webserver. - AnyEvent::FastPing The fastest ping in the west. @@ -1347,7 +1370,7 @@ 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 conenction and other + likely small, as the program has to handle connection and other failures anyways. Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over @@ -1591,7 +1614,7 @@ ... }); - EV::loop; + EV::run; 3b. The module user could use AnyEvent, too: @@ -2037,17 +2060,34 @@ 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 OR you must do - something completely out of the scope of AnyEvent. + something completely out of the scope of AnyEvent (see below). The problem of doing event processing in the parent *and* the child is much more complicated: even for backends that *are* 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 "exec" to - start worker children from some kind of manage rprocess is usually + parent and child, which is almost never what you want. Using "exec" to + start worker children from some kind of manage prrocess is usually preferred, because it is much easier and cleaner, at the expense of having to have another binary. + In addition to logical problems with fork, there are also implementation + problems. For example, on POSIX systems, you cannot fork at all in Perl + code if a thread (I am talking of pthreads here) was ever created in the + process, and this is just the tip of the iceberg. In general, using fork + from Perl is difficult, and attempting to use fork without an exec to + implement some kind of parallel processing is almost certainly doomed. + + To safely fork and exec, you should use a module such as Proc::FastSpawn + that let's you safely fork and exec new processes. + + If you want to do multiprocessing using processes, you can look at the + AnyEvent::Fork module (and some related modules such as + AnyEvent::Fork::RPC, AnyEvent::Fork::Pool and AnyEvent::Fork::Remote). + This module allows you to safely create subprocesses without any + limitations - you can use X11 toolkits or AnyEvent in the children + created by AnyEvent::Fork safely and without any special precautions. + SECURITY CONSIDERATIONS AnyEvent can be forced to load any event model via $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used @@ -2091,12 +2131,13 @@ AnyEvent::Debug (interactive shell, watcher tracing). Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event, - Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK. + Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK, Cocoa::EventLoop, UV. 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::FLTK. + AnyEvent::Impl::IOAsync, AnyEvent::Impl::Irssi, AnyEvent::Impl::FLTK, + AnyEvent::Impl::Cocoa, AnyEvent::Impl::UV. Non-blocking handles, pipes, stream sockets, TCP clients and servers: AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.