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Comparing libev/ev.pod (file contents):
Revision 1.139 by root, Wed Apr 2 05:51:40 2008 UTC vs.
Revision 1.143 by root, Sun Apr 6 14:34:52 2008 UTC

… …
358For few fds, this backend is a bit little slower than poll and select, 358For few fds, this backend is a bit little slower than poll and select,
359but it scales phenomenally better. While poll and select usually scale 359but it scales phenomenally better. While poll and select usually scale
360like O(total_fds) where n is the total number of fds (or the highest fd), 360like O(total_fds) where n is the total number of fds (or the highest fd),
361epoll scales either O(1) or O(active_fds). The epoll design has a number 361epoll scales either O(1) or O(active_fds). The epoll design has a number
362of shortcomings, such as silently dropping events in some hard-to-detect 362of shortcomings, such as silently dropping events in some hard-to-detect
363cases and rewiring a syscall per fd change, no fork support and bad 363cases and requiring a syscall per fd change, no fork support and bad
364support for dup. 364support for dup.
365 365
366While stopping, setting and starting an I/O watcher in the same iteration 366While stopping, setting and starting an I/O watcher in the same iteration
367will result in some caching, there is still a syscall per such incident 367will result in some caching, there is still a syscall per such incident
368(because the fd could point to a different file description now), so its 368(because the fd could point to a different file description now), so its
… …
2288 2288
2289This call incurs the overhead of a syscall only once per loop iteration, 2289This call incurs the overhead of a syscall only once per loop iteration,
2290so while the overhead might be noticable, it doesn't apply to repeated 2290so while the overhead might be noticable, it doesn't apply to repeated
2291calls to C<ev_async_send>. 2291calls to C<ev_async_send>.
2292 2292
2293=item bool = ev_async_pending (ev_async *)
2294
2295Returns a non-zero value when C<ev_async_send> has been called on the
2296watcher but the event has not yet been processed (or even noted) by the
2297event loop.
2298
2299C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2300the loop iterates next and checks for the watcher to have become active,
2301it will reset the flag again. C<ev_async_pending> can be used to very
2302quickly check wether invoking the loop might be a good idea.
2303
2304Not that this does I<not> check wether the watcher itself is pending, only
2305wether it has been requested to make this watcher pending.
2306
2293=back 2307=back
2294 2308
2295 2309
2296=head1 OTHER FUNCTIONS 2310=head1 OTHER FUNCTIONS
2297 2311
… …
2619=item C<EV_DEFAULT>, C<EV_DEFAULT_> 2633=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2620 2634
2621Similar to the other two macros, this gives you the value of the default 2635Similar to the other two macros, this gives you the value of the default
2622loop, if multiple loops are supported ("ev loop default"). 2636loop, if multiple loops are supported ("ev loop default").
2623 2637
2638=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
2639
2640Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
2641default loop has been initialised (C<UC> == unchecked). Their behaviour
2642is undefined when the default loop has not been initialised by a previous
2643execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
2644
2645It is often prudent to use C<EV_DEFAULT> when initialising the first
2646watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2647
2624=back 2648=back
2625 2649
2626Example: Declare and initialise a check watcher, utilising the above 2650Example: Declare and initialise a check watcher, utilising the above
2627macros so it will work regardless of whether multiple loops are supported 2651macros so it will work regardless of whether multiple loops are supported
2628or not. 2652or not.
… …
2723 2747
2724 libev.m4 2748 libev.m4
2725 2749
2726=head2 PREPROCESSOR SYMBOLS/MACROS 2750=head2 PREPROCESSOR SYMBOLS/MACROS
2727 2751
2728Libev can be configured via a variety of preprocessor symbols you have to define 2752Libev can be configured via a variety of preprocessor symbols you have to
2729before including any of its files. The default is not to build for multiplicity 2753define before including any of its files. The default in the absense of
2730and only include the select backend. 2754autoconf is noted for every option.
2731 2755
2732=over 4 2756=over 4
2733 2757
2734=item EV_STANDALONE 2758=item EV_STANDALONE
2735 2759
… …
2761=item EV_USE_NANOSLEEP 2785=item EV_USE_NANOSLEEP
2762 2786
2763If defined to be C<1>, libev will assume that C<nanosleep ()> is available 2787If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2764and will use it for delays. Otherwise it will use C<select ()>. 2788and will use it for delays. Otherwise it will use C<select ()>.
2765 2789
2790=item EV_USE_EVENTFD
2791
2792If defined to be C<1>, then libev will assume that C<eventfd ()> is
2793available and will probe for kernel support at runtime. This will improve
2794C<ev_signal> and C<ev_async> performance and reduce resource consumption.
2795If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
27962.7 or newer, otherwise disabled.
2797
2766=item EV_USE_SELECT 2798=item EV_USE_SELECT
2767 2799
2768If undefined or defined to be C<1>, libev will compile in support for the 2800If undefined or defined to be C<1>, libev will compile in support for the
2769C<select>(2) backend. No attempt at autodetection will be done: if no 2801C<select>(2) backend. No attempt at autodetection will be done: if no
2770other method takes over, select will be it. Otherwise the select backend 2802other method takes over, select will be it. Otherwise the select backend
… …
2806 2838
2807=item EV_USE_EPOLL 2839=item EV_USE_EPOLL
2808 2840
2809If defined to be C<1>, libev will compile in support for the Linux 2841If defined to be C<1>, libev will compile in support for the Linux
2810C<epoll>(7) backend. Its availability will be detected at runtime, 2842C<epoll>(7) backend. Its availability will be detected at runtime,
2811otherwise another method will be used as fallback. This is the 2843otherwise another method will be used as fallback. This is the preferred
2812preferred backend for GNU/Linux systems. 2844backend for GNU/Linux systems. If undefined, it will be enabled if the
2845headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2813 2846
2814=item EV_USE_KQUEUE 2847=item EV_USE_KQUEUE
2815 2848
2816If defined to be C<1>, libev will compile in support for the BSD style 2849If defined to be C<1>, libev will compile in support for the BSD style
2817C<kqueue>(2) backend. Its actual availability will be detected at runtime, 2850C<kqueue>(2) backend. Its actual availability will be detected at runtime,
… …
2836 2869
2837=item EV_USE_INOTIFY 2870=item EV_USE_INOTIFY
2838 2871
2839If defined to be C<1>, libev will compile in support for the Linux inotify 2872If defined to be C<1>, libev will compile in support for the Linux inotify
2840interface to speed up C<ev_stat> watchers. Its actual availability will 2873interface to speed up C<ev_stat> watchers. Its actual availability will
2841be detected at runtime. 2874be detected at runtime. If undefined, it will be enabled if the headers
2875indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2842 2876
2843=item EV_ATOMIC_T 2877=item EV_ATOMIC_T
2844 2878
2845Libev requires an integer type (suitable for storing C<0> or C<1>) whose 2879Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2846access is atomic with respect to other threads or signal contexts. No such 2880access is atomic with respect to other threads or signal contexts. No such

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