--- AnyEvent/lib/AnyEvent.pm 2009/11/17 01:19:49 1.296 +++ AnyEvent/lib/AnyEvent.pm 2010/02/10 13:33:44 1.311 @@ -405,6 +405,23 @@ 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 @@ -488,16 +505,19 @@ $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 -attention by the event loop". - -Idle watchers ideally get invoked when the event loop has nothing -better to do, just before it would block the process to wait for new -events. Instead of blocking, the idle watcher is invoked. +Repeatedly invoke the callback after the process becomes idle, until +either the watcher is destroyed or new events have been detected. -Most event loops unfortunately do not really support idle watchers (only +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". @@ -951,13 +971,26 @@ array will be ignored. Best use C when your application allows -it,as it takes care of these details. +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 =head1 WHAT TO DO IN A MODULE @@ -1116,8 +1149,8 @@ # basically a tuned-down version of common::sense sub common_sense { # from common:.sense 1.0 - ${^WARNING_BITS} = "\xfc\x3f\xf3\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03"; - # use strict vars subs + ${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x00"; + # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl) $^H |= 0x00000600; } @@ -1125,7 +1158,7 @@ use Carp (); -our $VERSION = '5.202'; +our $VERSION = '5.24'; our $MODEL; our $AUTOLOAD; @@ -1133,13 +1166,12 @@ our @REGISTRY; -our $WIN32; - our $VERBOSE; BEGIN { - eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }"; - eval "sub TAINT(){ " . (${^TAINT}*1) . " }"; + eval "sub CYGWIN(){" . (($^O =~ /cygwin/i) *1) . "}"; + eval "sub WIN32 (){" . (($^O =~ /mswin32/i)*1) . "}"; + eval "sub TAINT (){" . (${^TAINT} *1) . "}"; delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} if ${^TAINT}; @@ -1360,7 +1392,7 @@ # if (eval "use POSIX (); (POSIX::times())... } else { warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE; - *_time = sub { time }; # epic fail + *_time = sub (){ time }; # epic fail } &_time @@ -2435,8 +2467,8 @@ 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. +This section explains which additional modules will be used, and how they +affect AnyEvent's operation. =over 4 @@ -2451,7 +2483,7 @@ 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 +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 @@ -2508,13 +2540,31 @@ =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 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