… | |
… | |
415 | not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's |
415 | not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's |
416 | pure perl implementation). |
416 | pure perl implementation). |
417 | |
417 | |
418 | =head3 Safe/Unsafe Signals |
418 | =head3 Safe/Unsafe Signals |
419 | |
419 | |
420 | Perl signals can be either "safe" (synchronous to opcode handling) or |
420 | Perl signals can be either "safe" (synchronous to opcode handling) |
421 | "unsafe" (asynchronous) - the former might get delayed indefinitely, the |
421 | or "unsafe" (asynchronous) - the former might delay signal delivery |
422 | latter might corrupt your memory. |
422 | indefinitely, the latter might corrupt your memory. |
423 | |
423 | |
424 | AnyEvent signal handlers are, in addition, synchronous to the event loop, |
424 | AnyEvent signal handlers are, in addition, synchronous to the event loop, |
425 | i.e. they will not interrupt your running perl program but will only be |
425 | i.e. they will not interrupt your running perl program but will only be |
426 | called as part of the normal event handling (just like timer, I/O etc. |
426 | called as part of the normal event handling (just like timer, I/O etc. |
427 | callbacks, too). |
427 | callbacks, too). |
428 | |
428 | |
429 | =head3 Signal Races, Delays and Workarounds |
429 | =head3 Signal Races, Delays and Workarounds |
430 | |
430 | |
431 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
431 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support |
432 | callbacks to signals in a generic way, which is a pity, as you cannot |
432 | attaching callbacks to signals in a generic way, which is a pity, |
433 | do race-free signal handling in perl, requiring C libraries for |
433 | as you cannot do race-free signal handling in perl, requiring |
434 | this. AnyEvent will try to do its best, which means in some cases, |
434 | C libraries for this. AnyEvent will try to do its best, which |
435 | signals will be delayed. The maximum time a signal might be delayed is |
435 | means in some cases, signals will be delayed. The maximum time |
436 | specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This |
436 | a signal might be delayed is 10 seconds by default, but can |
437 | variable can be changed only before the first signal watcher is created, |
437 | be overriden via C<$ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY}> or |
438 | and should be left alone otherwise. This variable determines how often |
438 | C<$AnyEvent::MAX_SIGNAL_LATENCY> - see the Ö<ENVIRONMENT VARIABLES> |
439 | AnyEvent polls for signals (in case a wake-up was missed). Higher values |
439 | section for details. |
440 | will cause fewer spurious wake-ups, which is better for power and CPU |
|
|
441 | saving. |
|
|
442 | |
440 | |
443 | All these problems can be avoided by installing the optional |
441 | All these problems can be avoided by installing the optional |
444 | L<Async::Interrupt> module, which works with most event loops. It will not |
442 | L<Async::Interrupt> module, which works with most event loops. It will not |
445 | work with inherently broken event loops such as L<Event> or L<Event::Lib> |
443 | work with inherently broken event loops such as L<Event> or L<Event::Lib> |
446 | (and not with L<POE> currently, as POE does its own workaround with |
444 | (and not with L<POE> currently). For those, you just have to suffer the |
447 | one-second latency). For those, you just have to suffer the delays. |
445 | delays. |
448 | |
446 | |
449 | =head2 CHILD PROCESS WATCHERS |
447 | =head2 CHILD PROCESS WATCHERS |
450 | |
448 | |
451 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
449 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
452 | |
450 | |
… | |
… | |
1240 | our $VERSION = '6.02'; |
1238 | our $VERSION = '6.02'; |
1241 | our $MODEL; |
1239 | our $MODEL; |
1242 | our @ISA; |
1240 | our @ISA; |
1243 | our @REGISTRY; |
1241 | our @REGISTRY; |
1244 | our $VERBOSE; |
1242 | our $VERBOSE; |
1245 | our $MAX_SIGNAL_LATENCY = 10; |
|
|
1246 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
1243 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
|
|
1244 | our $MAX_SIGNAL_LATENCY = $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} || 10; # executes after the BEGIN block below (tainting!) |
1247 | |
1245 | |
1248 | BEGIN { |
1246 | BEGIN { |
1249 | require "AnyEvent/constants.pl"; |
1247 | require "AnyEvent/constants.pl"; |
1250 | |
1248 | |
1251 | eval "sub TAINT (){" . (${^TAINT}*1) . "}"; |
1249 | eval "sub TAINT (){" . (${^TAINT}*1) . "}"; |
… | |
… | |
2227 | |
2225 | |
2228 | The default value for the C<max_outstanding> parameter for the default DNS |
2226 | The default value for the C<max_outstanding> parameter for the default DNS |
2229 | resolver - this is the maximum number of parallel DNS requests that are |
2227 | resolver - this is the maximum number of parallel DNS requests that are |
2230 | sent to the DNS server. |
2228 | sent to the DNS server. |
2231 | |
2229 | |
|
|
2230 | =item C<PERL_ANYEVENT_MAX_SIGNAL_LATENCY> |
|
|
2231 | |
|
|
2232 | Perl has inherently racy signal handling (you can basically choose between |
|
|
2233 | losing signals and memory corruption) - pure perl event loops (including |
|
|
2234 | C<AnyEvent::Loop>, when C<Async::Interrupt> isn't available) therefore |
|
|
2235 | have to poll regularly to avoid losing signals. |
|
|
2236 | |
|
|
2237 | Some event loops are racy, but don't poll regularly, and some event loops |
|
|
2238 | are written in C but are still racy. For those event loops, AnyEvent |
|
|
2239 | installs a timer that regularly wakes up the event loop. |
|
|
2240 | |
|
|
2241 | By default, the interval for this timer is C<10> seconds, but you can |
|
|
2242 | override this delay with this environment variable (or by setting |
|
|
2243 | the C<$AnyEvent::MAX_SIGNAL_LATENCY> variable before creating signal |
|
|
2244 | watchers). |
|
|
2245 | |
|
|
2246 | Lower values increase CPU (and energy) usage, higher values can introduce |
|
|
2247 | long delays when reaping children or waiting for signals. |
|
|
2248 | |
|
|
2249 | The L<AnyEvent::Async> module, if available, will be used to avoid this |
|
|
2250 | polling (with most event loops). |
|
|
2251 | |
2232 | =item C<PERL_ANYEVENT_RESOLV_CONF> |
2252 | =item C<PERL_ANYEVENT_RESOLV_CONF> |
2233 | |
2253 | |
2234 | The absolute path to a F<resolv.conf>-style file to use instead of |
2254 | The absolute path to a F<resolv.conf>-style file to use instead of |
2235 | F</etc/resolv.conf> (or the OS-specific configuration) in the default |
2255 | F</etc/resolv.conf> (or the OS-specific configuration) in the default |
2236 | resolver, or the empty string to select the default configuration. |
2256 | resolver, or the empty string to select the default configuration. |