… | |
… | |
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 | |
… | |
… | |
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. |
|
|
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_NOSIGNALFD> |
|
|
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. |
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, |
… | |
… | |
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 |
|
|
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?"); |
… | |
… | |
862 | |
879 | |
863 | This call will simply invoke all pending watchers while resetting their |
880 | This call will simply invoke all pending watchers while resetting their |
864 | pending state. Normally, C<ev_loop> does this automatically when required, |
881 | pending state. Normally, C<ev_loop> does this automatically when required, |
865 | but when overriding the invoke callback this call comes handy. |
882 | but when overriding the invoke callback this call comes handy. |
866 | |
883 | |
|
|
884 | =item int ev_pending_count (loop) |
|
|
885 | |
|
|
886 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
887 | are pending. |
|
|
888 | |
867 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
889 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
868 | |
890 | |
869 | This overrides the invoke pending functionality of the loop: Instead of |
891 | This overrides the invoke pending functionality of the loop: Instead of |
870 | invoking all pending watchers when there are any, C<ev_loop> will call |
892 | invoking all pending watchers when there are any, C<ev_loop> will call |
871 | this callback instead. This is useful, for example, when you want to |
893 | this callback instead. This is useful, for example, when you want to |
… | |
… | |
1750 | |
1772 | |
1751 | If the event loop is suspended for a long time, you can also force an |
1773 | If the event loop is suspended for a long time, you can also force an |
1752 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1774 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1753 | ()>. |
1775 | ()>. |
1754 | |
1776 | |
|
|
1777 | =head3 The special problems of suspended animation |
|
|
1778 | |
|
|
1779 | When you leave the server world it is quite customary to hit machines that |
|
|
1780 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1781 | |
|
|
1782 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1783 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1784 | to run until the system is suspended, but they will not advance while the |
|
|
1785 | system is suspended. That means, on resume, it will be as if the program |
|
|
1786 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1787 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1788 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1789 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1790 | be adjusted accordingly. |
|
|
1791 | |
|
|
1792 | I would not be surprised to see different behaviour in different between |
|
|
1793 | operating systems, OS versions or even different hardware. |
|
|
1794 | |
|
|
1795 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1796 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1797 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1798 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1799 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1800 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1801 | |
|
|
1802 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1803 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1804 | deterministic behaviour in this case (you can do nothing against |
|
|
1805 | C<SIGSTOP>). |
|
|
1806 | |
1755 | =head3 Watcher-Specific Functions and Data Members |
1807 | =head3 Watcher-Specific Functions and Data Members |
1756 | |
1808 | |
1757 | =over 4 |
1809 | =over 4 |
1758 | |
1810 | |
1759 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1811 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1784 | If the timer is repeating, either start it if necessary (with the |
1836 | If the timer is repeating, either start it if necessary (with the |
1785 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1837 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1786 | |
1838 | |
1787 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1839 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1788 | usage example. |
1840 | usage example. |
|
|
1841 | |
|
|
1842 | =item ev_timer_remaining (loop, ev_timer *) |
|
|
1843 | |
|
|
1844 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1845 | then this time is relative to the current event loop time, otherwise it's |
|
|
1846 | the timeout value currently configured. |
|
|
1847 | |
|
|
1848 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
1849 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
|
|
1850 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
1851 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
1852 | too), and so on. |
1789 | |
1853 | |
1790 | =item ev_tstamp repeat [read-write] |
1854 | =item ev_tstamp repeat [read-write] |
1791 | |
1855 | |
1792 | The current C<repeat> value. Will be used each time the watcher times out |
1856 | The current C<repeat> value. Will be used each time the watcher times out |
1793 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1857 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
2029 | 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 |
2030 | 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 |
2031 | 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 |
2032 | normal event processing, like any other event. |
2096 | normal event processing, like any other event. |
2033 | |
2097 | |
2034 | If you want signals asynchronously, just use C<sigaction> as you would |
2098 | If you want signals to be delivered truly asynchronously, just use |
2035 | do without libev and forget about sharing the signal. You can even use |
2099 | C<sigaction> as you would do without libev and forget about sharing |
2036 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2100 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2101 | synchronously wake up an event loop. |
2037 | |
2102 | |
2038 | 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 |
|
|
2104 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2105 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2106 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2107 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2108 | |
2039 | first watcher gets started will libev actually register a signal handler |
2109 | When the first watcher gets started will libev actually register something |
2040 | with the kernel (thus it coexists with your own signal handlers as long as |
2110 | with the kernel (thus it coexists with your own signal handlers as long as |
2041 | you don't register any with libev for the same signal). Similarly, when |
2111 | you don't register any with libev for the same signal). |
2042 | the last signal watcher for a signal is stopped, libev will reset the |
2112 | |
2043 | signal handler to SIG_DFL (regardless of what it was set to before). |
2113 | Both the signal mask state (C<sigprocmask>) and the signal handler state |
|
|
2114 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2115 | sotpping it again), that is, libev might or might not block the signal, |
|
|
2116 | and might or might not set or restore the installed signal handler. |
2044 | |
2117 | |
2045 | If possible and supported, libev will install its handlers with |
2118 | If possible and supported, libev will install its handlers with |
2046 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2119 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2047 | interrupted. If you have a problem with system calls getting interrupted by |
2120 | not be unduly interrupted. If you have a problem with system calls getting |
2048 | signals you can block all signals in an C<ev_check> watcher and unblock |
2121 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2049 | them in an C<ev_prepare> watcher. |
2122 | and unblock them in an C<ev_prepare> watcher. |
2050 | |
2123 | |
2051 | =head3 Watcher-Specific Functions and Data Members |
2124 | =head3 Watcher-Specific Functions and Data Members |
2052 | |
2125 | |
2053 | =over 4 |
2126 | =over 4 |
2054 | |
2127 | |
… | |
… | |
2099 | libev) |
2172 | libev) |
2100 | |
2173 | |
2101 | =head3 Process Interaction |
2174 | =head3 Process Interaction |
2102 | |
2175 | |
2103 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2176 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2104 | initialised. This is necessary to guarantee proper behaviour even if |
2177 | initialised. This is necessary to guarantee proper behaviour even if the |
2105 | the first child watcher is started after the child exits. The occurrence |
2178 | first child watcher is started after the child exits. The occurrence |
2106 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2179 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2107 | synchronously as part of the event loop processing. Libev always reaps all |
2180 | synchronously as part of the event loop processing. Libev always reaps all |
2108 | children, even ones not watched. |
2181 | children, even ones not watched. |
2109 | |
2182 | |
2110 | =head3 Overriding the Built-In Processing |
2183 | =head3 Overriding the Built-In Processing |
… | |
… | |
2120 | =head3 Stopping the Child Watcher |
2193 | =head3 Stopping the Child Watcher |
2121 | |
2194 | |
2122 | Currently, the child watcher never gets stopped, even when the |
2195 | Currently, the child watcher never gets stopped, even when the |
2123 | child terminates, so normally one needs to stop the watcher in the |
2196 | child terminates, so normally one needs to stop the watcher in the |
2124 | callback. Future versions of libev might stop the watcher automatically |
2197 | callback. Future versions of libev might stop the watcher automatically |
2125 | when a child exit is detected. |
2198 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2199 | problem). |
2126 | |
2200 | |
2127 | =head3 Watcher-Specific Functions and Data Members |
2201 | =head3 Watcher-Specific Functions and Data Members |
2128 | |
2202 | |
2129 | =over 4 |
2203 | =over 4 |
2130 | |
2204 | |
… | |
… | |
3508 | keeps libev from including F<config.h>, and it also defines dummy |
3582 | keeps libev from including F<config.h>, and it also defines dummy |
3509 | implementations for some libevent functions (such as logging, which is not |
3583 | implementations for some libevent functions (such as logging, which is not |
3510 | supported). It will also not define any of the structs usually found in |
3584 | supported). It will also not define any of the structs usually found in |
3511 | F<event.h> that are not directly supported by the libev core alone. |
3585 | F<event.h> that are not directly supported by the libev core alone. |
3512 | |
3586 | |
3513 | In stanbdalone mode, libev will still try to automatically deduce the |
3587 | In standalone mode, libev will still try to automatically deduce the |
3514 | configuration, but has to be more conservative. |
3588 | configuration, but has to be more conservative. |
3515 | |
3589 | |
3516 | =item EV_USE_MONOTONIC |
3590 | =item EV_USE_MONOTONIC |
3517 | |
3591 | |
3518 | If defined to be C<1>, libev will try to detect the availability of the |
3592 | If defined to be C<1>, libev will try to detect the availability of the |
… | |
… | |
3745 | 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 |
3746 | 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 |
3747 | 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 |
3748 | over time. |
3822 | over time. |
3749 | |
3823 | |
|
|
3824 | =item EV_NSIG |
|
|
3825 | |
|
|
3826 | The highest supported signal number, +1 (or, the number of |
|
|
3827 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
3828 | automatically, but sometimes this fails, in which case it can be |
|
|
3829 | specified. Also, using a lower number than detected (C<32> should be |
|
|
3830 | good for about any system in existance) can save some memory, as libev |
|
|
3831 | statically allocates some 12-24 bytes per signal number. |
|
|
3832 | |
3750 | =item EV_PID_HASHSIZE |
3833 | =item EV_PID_HASHSIZE |
3751 | |
3834 | |
3752 | 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 |
3753 | 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 |
3754 | 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 |
… | |
… | |
4028 | } |
4111 | } |
4029 | |
4112 | |
4030 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
4113 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
4031 | signal the main thread via some unspecified mechanism (signals? pipe |
4114 | signal the main thread via some unspecified mechanism (signals? pipe |
4032 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
4115 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
4033 | have been called: |
4116 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4117 | and b) skipping inter-thread-communication when there are no pending |
|
|
4118 | watchers is very beneficial): |
4034 | |
4119 | |
4035 | static void |
4120 | static void |
4036 | l_invoke (EV_P) |
4121 | l_invoke (EV_P) |
4037 | { |
4122 | { |
4038 | userdata *u = ev_userdata (EV_A); |
4123 | userdata *u = ev_userdata (EV_A); |
4039 | |
4124 | |
|
|
4125 | while (ev_pending_count (EV_A)) |
|
|
4126 | { |
4040 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
4127 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
4041 | |
|
|
4042 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
4128 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4129 | } |
4043 | } |
4130 | } |
4044 | |
4131 | |
4045 | Now, whenever the main thread gets told to invoke pending watchers, it |
4132 | Now, whenever the main thread gets told to invoke pending watchers, it |
4046 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
4133 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
4047 | thread to continue: |
4134 | thread to continue: |