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98 | =head2 FEATURES |
98 | =head2 FEATURES |
99 | |
99 | |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
103 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
104 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
105 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
106 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
107 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
107 | change events (C<ev_child>), and event watchers dealing with the event |
108 | file watchers (C<ev_stat>) and even limited support for fork events |
108 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
109 | (C<ev_fork>). |
109 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
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110 | limited support for fork events (C<ev_fork>). |
110 | |
111 | |
111 | It also is quite fast (see this |
112 | It also is quite fast (see this |
112 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | for example). |
114 | for example). |
114 | |
115 | |
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361 | forget about forgetting to tell libev about forking) when you use this |
362 | forget about forgetting to tell libev about forking) when you use this |
362 | flag. |
363 | flag. |
363 | |
364 | |
364 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | environment variable. |
366 | environment variable. |
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367 | |
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368 | =item C<EVFLAG_NOINOTIFY> |
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369 | |
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370 | When this flag is specified, then libev will not attempt to use the |
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371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
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372 | testing, this flag can be useful to conserve inotify file descriptors, as |
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373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
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374 | |
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375 | =item C<EVFLAG_NOSIGNALFD> |
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376 | |
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377 | When this flag is specified, then libev will not attempt to use the |
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378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
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379 | probably only useful to work around any bugs in libev. Consequently, this |
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380 | flag might go away once the signalfd functionality is considered stable, |
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381 | so it's useful mostly in environment variables and not in program code. |
366 | |
382 | |
367 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
383 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
368 | |
384 | |
369 | This is your standard select(2) backend. Not I<completely> standard, as |
385 | This is your standard select(2) backend. Not I<completely> standard, as |
370 | libev tries to roll its own fd_set with no limits on the number of fds, |
386 | libev tries to roll its own fd_set with no limits on the number of fds, |
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518 | |
534 | |
519 | It is definitely not recommended to use this flag. |
535 | It is definitely not recommended to use this flag. |
520 | |
536 | |
521 | =back |
537 | =back |
522 | |
538 | |
523 | If one or more of these are or'ed into the flags value, then only these |
539 | If one or more of the backend flags are or'ed into the flags value, |
524 | backends will be tried (in the reverse order as listed here). If none are |
540 | then only these backends will be tried (in the reverse order as listed |
525 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
541 | here). If none are specified, all backends in C<ev_recommended_backends |
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542 | ()> will be tried. |
526 | |
543 | |
527 | Example: This is the most typical usage. |
544 | Example: This is the most typical usage. |
528 | |
545 | |
529 | if (!ev_default_loop (0)) |
546 | if (!ev_default_loop (0)) |
530 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
547 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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2076 | Signal watchers will trigger an event when the process receives a specific |
2093 | Signal watchers will trigger an event when the process receives a specific |
2077 | signal one or more times. Even though signals are very asynchronous, libev |
2094 | signal one or more times. Even though signals are very asynchronous, libev |
2078 | will try it's best to deliver signals synchronously, i.e. as part of the |
2095 | will try it's best to deliver signals synchronously, i.e. as part of the |
2079 | normal event processing, like any other event. |
2096 | normal event processing, like any other event. |
2080 | |
2097 | |
2081 | Note that only the default loop supports registering signal watchers |
2098 | If you want signals to be delivered truly asynchronously, just use |
2082 | currently. |
2099 | C<sigaction> as you would do without libev and forget about sharing |
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2100 | the signal. You can even use C<ev_async> from a signal handler to |
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2101 | synchronously wake up an event loop. |
2083 | |
2102 | |
2084 | If you want signals asynchronously, just use C<sigaction> as you would |
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2085 | do without libev and forget about sharing the signal. You can even use |
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2086 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
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2087 | |
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2088 | You can configure as many watchers as you like per signal. Only when the |
2103 | You can configure as many watchers as you like for the same signal, but |
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2104 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
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2105 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
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2106 | C<SIGINT> in both the default loop and another loop at the same time. At |
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2107 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
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2108 | |
2089 | first watcher gets started will libev actually register something with |
2109 | When the first watcher gets started will libev actually register something |
2090 | the kernel (thus it coexists with your own signal handlers as long as you |
2110 | with the kernel (thus it coexists with your own signal handlers as long as |
2091 | don't register any with libev for the same signal). |
2111 | you don't register any with libev for the same signal). |
2092 | |
2112 | |
2093 | Both the signal mask state (C<sigprocmask>) and the signal handler state |
2113 | Both the signal mask state (C<sigprocmask>) and the signal handler state |
2094 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2114 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2095 | sotpping it again), that is, libev might or might not block the signal, |
2115 | sotpping it again), that is, libev might or might not block the signal, |
2096 | and might or might not set or restore the installed signal handler. |
2116 | and might or might not set or restore the installed signal handler. |
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3799 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3819 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3800 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3820 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3801 | of the API are still available, and do not complain if this subset changes |
3821 | of the API are still available, and do not complain if this subset changes |
3802 | over time. |
3822 | over time. |
3803 | |
3823 | |
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3824 | =item EV_NSIG |
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3825 | |
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3826 | The highest supported signal number, +1 (or, the number of |
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3827 | signals): Normally, libev tries to deduce the maximum number of signals |
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3828 | automatically, but sometimes this fails, in which case it can be |
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3829 | specified. Also, using a lower number than detected (C<32> should be |
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3830 | good for about any system in existance) can save some memory, as libev |
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3831 | statically allocates some 12-24 bytes per signal number. |
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3832 | |
3804 | =item EV_PID_HASHSIZE |
3833 | =item EV_PID_HASHSIZE |
3805 | |
3834 | |
3806 | C<ev_child> watchers use a small hash table to distribute workload by |
3835 | C<ev_child> watchers use a small hash table to distribute workload by |
3807 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3836 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3808 | than enough. If you need to manage thousands of children you might want to |
3837 | than enough. If you need to manage thousands of children you might want to |