… | |
… | |
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 |
|
|
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 | |
… | |
… | |
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. |
366 | |
367 | |
|
|
368 | =item C<EVFLAG_NOINOTIFY> |
|
|
369 | |
|
|
370 | When this flag is specified, then libev will not attempt to use the |
|
|
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
|
|
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
|
|
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
|
|
374 | |
|
|
375 | =item C<EVFLAG_NOSIGFD> |
|
|
376 | |
|
|
377 | When this flag is specified, then libev will not attempt to use the |
|
|
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
|
|
379 | probably only useful to work around any bugs in libev. Consequently, this |
|
|
380 | flag might go away once the signalfd functionality is considered stable, |
|
|
381 | so it's useful mostly in environment variables and not in program code. |
|
|
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, |
371 | but if that fails, expect a fairly low limit on the number of fds when |
387 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
394 | |
410 | |
395 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
411 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
396 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
412 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
397 | |
413 | |
398 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
414 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
415 | |
|
|
416 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
417 | kernels). |
399 | |
418 | |
400 | For few fds, this backend is a bit little slower than poll and select, |
419 | For few fds, this backend is a bit little slower than poll and select, |
401 | but it scales phenomenally better. While poll and select usually scale |
420 | but it scales phenomenally better. While poll and select usually scale |
402 | like O(total_fds) where n is the total number of fds (or the highest fd), |
421 | like O(total_fds) where n is the total number of fds (or the highest fd), |
403 | epoll scales either O(1) or O(active_fds). |
422 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
518 | |
537 | |
519 | It is definitely not recommended to use this flag. |
538 | It is definitely not recommended to use this flag. |
520 | |
539 | |
521 | =back |
540 | =back |
522 | |
541 | |
523 | If one or more of these are or'ed into the flags value, then only these |
542 | 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 |
543 | 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. |
544 | here). If none are specified, all backends in C<ev_recommended_backends |
|
|
545 | ()> will be tried. |
526 | |
546 | |
527 | Example: This is the most typical usage. |
547 | Example: This is the most typical usage. |
528 | |
548 | |
529 | if (!ev_default_loop (0)) |
549 | if (!ev_default_loop (0)) |
530 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
550 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
573 | as signal and child watchers) would need to be stopped manually. |
593 | as signal and child watchers) would need to be stopped manually. |
574 | |
594 | |
575 | In general it is not advisable to call this function except in the |
595 | In general it is not advisable to call this function except in the |
576 | rare occasion where you really need to free e.g. the signal handling |
596 | rare occasion where you really need to free e.g. the signal handling |
577 | pipe fds. If you need dynamically allocated loops it is better to use |
597 | pipe fds. If you need dynamically allocated loops it is better to use |
578 | C<ev_loop_new> and C<ev_loop_destroy>). |
598 | C<ev_loop_new> and C<ev_loop_destroy>. |
579 | |
599 | |
580 | =item ev_loop_destroy (loop) |
600 | =item ev_loop_destroy (loop) |
581 | |
601 | |
582 | Like C<ev_default_destroy>, but destroys an event loop created by an |
602 | Like C<ev_default_destroy>, but destroys an event loop created by an |
583 | earlier call to C<ev_loop_new>. |
603 | earlier call to C<ev_loop_new>. |
… | |
… | |
687 | event loop time (see C<ev_now_update>). |
707 | event loop time (see C<ev_now_update>). |
688 | |
708 | |
689 | =item ev_loop (loop, int flags) |
709 | =item ev_loop (loop, int flags) |
690 | |
710 | |
691 | Finally, this is it, the event handler. This function usually is called |
711 | Finally, this is it, the event handler. This function usually is called |
692 | after you initialised all your watchers and you want to start handling |
712 | after you have initialised all your watchers and you want to start |
693 | events. |
713 | handling events. |
694 | |
714 | |
695 | If the flags argument is specified as C<0>, it will not return until |
715 | If the flags argument is specified as C<0>, it will not return until |
696 | either no event watchers are active anymore or C<ev_unloop> was called. |
716 | either no event watchers are active anymore or C<ev_unloop> was called. |
697 | |
717 | |
698 | Please note that an explicit C<ev_unloop> is usually better than |
718 | Please note that an explicit C<ev_unloop> is usually better than |
… | |
… | |
2076 | Signal watchers will trigger an event when the process receives a specific |
2096 | 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 |
2097 | 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 |
2098 | will try it's best to deliver signals synchronously, i.e. as part of the |
2079 | normal event processing, like any other event. |
2099 | normal event processing, like any other event. |
2080 | |
2100 | |
2081 | If you want signals asynchronously, just use C<sigaction> as you would |
2101 | If you want signals to be delivered truly asynchronously, just use |
2082 | do without libev and forget about sharing the signal. You can even use |
2102 | C<sigaction> as you would do without libev and forget about sharing |
2083 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2103 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2104 | synchronously wake up an event loop. |
2084 | |
2105 | |
2085 | You can configure as many watchers as you like per signal. Only when the |
2106 | You can configure as many watchers as you like for the same signal, but |
|
|
2107 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2108 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2109 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2110 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2111 | |
2086 | first watcher gets started will libev actually register a signal handler |
2112 | When the first watcher gets started will libev actually register something |
2087 | with the kernel (thus it coexists with your own signal handlers as long as |
2113 | with the kernel (thus it coexists with your own signal handlers as long as |
2088 | you don't register any with libev for the same signal). Similarly, when |
2114 | you don't register any with libev for the same signal). |
2089 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
2090 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
2091 | |
2115 | |
2092 | If possible and supported, libev will install its handlers with |
2116 | If possible and supported, libev will install its handlers with |
2093 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2117 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2094 | interrupted. If you have a problem with system calls getting interrupted by |
2118 | not be unduly interrupted. If you have a problem with system calls getting |
2095 | signals you can block all signals in an C<ev_check> watcher and unblock |
2119 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2096 | them in an C<ev_prepare> watcher. |
2120 | and unblock them in an C<ev_prepare> watcher. |
|
|
2121 | |
|
|
2122 | =head3 The special problem of inheritance over execve |
|
|
2123 | |
|
|
2124 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2125 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2126 | stopping it again), that is, libev might or might not block the signal, |
|
|
2127 | and might or might not set or restore the installed signal handler. |
|
|
2128 | |
|
|
2129 | While this does not matter for the signal disposition (libev never |
|
|
2130 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2131 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2132 | certain signals to be blocked. |
|
|
2133 | |
|
|
2134 | This means that before calling C<exec> (from the child) you should reset |
|
|
2135 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2136 | choice usually). |
|
|
2137 | |
|
|
2138 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2139 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2140 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2141 | |
|
|
2142 | In current versions of libev, you can also ensure that the signal mask is |
|
|
2143 | not blocking any signals (except temporarily, so thread users watch out) |
|
|
2144 | by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This |
|
|
2145 | is not guaranteed for future versions, however. |
2097 | |
2146 | |
2098 | =head3 Watcher-Specific Functions and Data Members |
2147 | =head3 Watcher-Specific Functions and Data Members |
2099 | |
2148 | |
2100 | =over 4 |
2149 | =over 4 |
2101 | |
2150 | |
… | |
… | |
2146 | libev) |
2195 | libev) |
2147 | |
2196 | |
2148 | =head3 Process Interaction |
2197 | =head3 Process Interaction |
2149 | |
2198 | |
2150 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2199 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2151 | initialised. This is necessary to guarantee proper behaviour even if |
2200 | initialised. This is necessary to guarantee proper behaviour even if the |
2152 | the first child watcher is started after the child exits. The occurrence |
2201 | first child watcher is started after the child exits. The occurrence |
2153 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2202 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2154 | synchronously as part of the event loop processing. Libev always reaps all |
2203 | synchronously as part of the event loop processing. Libev always reaps all |
2155 | children, even ones not watched. |
2204 | children, even ones not watched. |
2156 | |
2205 | |
2157 | =head3 Overriding the Built-In Processing |
2206 | =head3 Overriding the Built-In Processing |
… | |
… | |
2167 | =head3 Stopping the Child Watcher |
2216 | =head3 Stopping the Child Watcher |
2168 | |
2217 | |
2169 | Currently, the child watcher never gets stopped, even when the |
2218 | Currently, the child watcher never gets stopped, even when the |
2170 | child terminates, so normally one needs to stop the watcher in the |
2219 | child terminates, so normally one needs to stop the watcher in the |
2171 | callback. Future versions of libev might stop the watcher automatically |
2220 | callback. Future versions of libev might stop the watcher automatically |
2172 | when a child exit is detected. |
2221 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2222 | problem). |
2173 | |
2223 | |
2174 | =head3 Watcher-Specific Functions and Data Members |
2224 | =head3 Watcher-Specific Functions and Data Members |
2175 | |
2225 | |
2176 | =over 4 |
2226 | =over 4 |
2177 | |
2227 | |
… | |
… | |
3380 | =item Ocaml |
3430 | =item Ocaml |
3381 | |
3431 | |
3382 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3432 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3383 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3433 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3384 | |
3434 | |
|
|
3435 | =item Lua |
|
|
3436 | |
|
|
3437 | Brian Maher has written a partial interface to libev |
|
|
3438 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
|
|
3439 | L<http://github.com/brimworks/lua-ev>. |
|
|
3440 | |
3385 | =back |
3441 | =back |
3386 | |
3442 | |
3387 | |
3443 | |
3388 | =head1 MACRO MAGIC |
3444 | =head1 MACRO MAGIC |
3389 | |
3445 | |
… | |
… | |
3555 | keeps libev from including F<config.h>, and it also defines dummy |
3611 | keeps libev from including F<config.h>, and it also defines dummy |
3556 | implementations for some libevent functions (such as logging, which is not |
3612 | implementations for some libevent functions (such as logging, which is not |
3557 | supported). It will also not define any of the structs usually found in |
3613 | supported). It will also not define any of the structs usually found in |
3558 | F<event.h> that are not directly supported by the libev core alone. |
3614 | F<event.h> that are not directly supported by the libev core alone. |
3559 | |
3615 | |
3560 | In stanbdalone mode, libev will still try to automatically deduce the |
3616 | In standalone mode, libev will still try to automatically deduce the |
3561 | configuration, but has to be more conservative. |
3617 | configuration, but has to be more conservative. |
3562 | |
3618 | |
3563 | =item EV_USE_MONOTONIC |
3619 | =item EV_USE_MONOTONIC |
3564 | |
3620 | |
3565 | If defined to be C<1>, libev will try to detect the availability of the |
3621 | If defined to be C<1>, libev will try to detect the availability of the |
… | |
… | |
3630 | be used is the winsock select). This means that it will call |
3686 | be used is the winsock select). This means that it will call |
3631 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3687 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3632 | it is assumed that all these functions actually work on fds, even |
3688 | it is assumed that all these functions actually work on fds, even |
3633 | on win32. Should not be defined on non-win32 platforms. |
3689 | on win32. Should not be defined on non-win32 platforms. |
3634 | |
3690 | |
3635 | =item EV_FD_TO_WIN32_HANDLE |
3691 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3636 | |
3692 | |
3637 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3693 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3638 | file descriptors to socket handles. When not defining this symbol (the |
3694 | file descriptors to socket handles. When not defining this symbol (the |
3639 | default), then libev will call C<_get_osfhandle>, which is usually |
3695 | default), then libev will call C<_get_osfhandle>, which is usually |
3640 | correct. In some cases, programs use their own file descriptor management, |
3696 | correct. In some cases, programs use their own file descriptor management, |
3641 | in which case they can provide this function to map fds to socket handles. |
3697 | in which case they can provide this function to map fds to socket handles. |
|
|
3698 | |
|
|
3699 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
3700 | |
|
|
3701 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
3702 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
3703 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3704 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3705 | |
|
|
3706 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
3707 | |
|
|
3708 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3709 | macro can be used to override the C<close> function, useful to unregister |
|
|
3710 | file descriptors again. Note that the replacement function has to close |
|
|
3711 | the underlying OS handle. |
3642 | |
3712 | |
3643 | =item EV_USE_POLL |
3713 | =item EV_USE_POLL |
3644 | |
3714 | |
3645 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3715 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3646 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3716 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3792 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3862 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3793 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3863 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3794 | of the API are still available, and do not complain if this subset changes |
3864 | of the API are still available, and do not complain if this subset changes |
3795 | over time. |
3865 | over time. |
3796 | |
3866 | |
|
|
3867 | =item EV_NSIG |
|
|
3868 | |
|
|
3869 | The highest supported signal number, +1 (or, the number of |
|
|
3870 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
3871 | automatically, but sometimes this fails, in which case it can be |
|
|
3872 | specified. Also, using a lower number than detected (C<32> should be |
|
|
3873 | good for about any system in existance) can save some memory, as libev |
|
|
3874 | statically allocates some 12-24 bytes per signal number. |
|
|
3875 | |
3797 | =item EV_PID_HASHSIZE |
3876 | =item EV_PID_HASHSIZE |
3798 | |
3877 | |
3799 | C<ev_child> watchers use a small hash table to distribute workload by |
3878 | C<ev_child> watchers use a small hash table to distribute workload by |
3800 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3879 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3801 | than enough. If you need to manage thousands of children you might want to |
3880 | than enough. If you need to manage thousands of children you might want to |