… | |
… | |
196 | See the description of C<ev_embed> watchers for more info. |
196 | See the description of C<ev_embed> watchers for more info. |
197 | |
197 | |
198 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
198 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
199 | |
199 | |
200 | Sets the allocation function to use (the prototype is similar - the |
200 | Sets the allocation function to use (the prototype is similar - the |
201 | semantics is identical - to the realloc C function). It is used to |
201 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
202 | allocate and free memory (no surprises here). If it returns zero when |
202 | used to allocate and free memory (no surprises here). If it returns zero |
203 | memory needs to be allocated, the library might abort or take some |
203 | when memory needs to be allocated (C<size != 0>), the library might abort |
204 | potentially destructive action. The default is your system realloc |
204 | or take some potentially destructive action. |
205 | function. |
205 | |
|
|
206 | Since some systems (at least OpenBSD and Darwin) fail to implement |
|
|
207 | correct C<realloc> semantics, libev will use a wrapper around the system |
|
|
208 | C<realloc> and C<free> functions by default. |
206 | |
209 | |
207 | You could override this function in high-availability programs to, say, |
210 | You could override this function in high-availability programs to, say, |
208 | free some memory if it cannot allocate memory, to use a special allocator, |
211 | free some memory if it cannot allocate memory, to use a special allocator, |
209 | or even to sleep a while and retry until some memory is available. |
212 | or even to sleep a while and retry until some memory is available. |
210 | |
213 | |
211 | Example: Replace the libev allocator with one that waits a bit and then |
214 | Example: Replace the libev allocator with one that waits a bit and then |
212 | retries). |
215 | retries (example requires a standards-compliant C<realloc>). |
213 | |
216 | |
214 | static void * |
217 | static void * |
215 | persistent_realloc (void *ptr, size_t size) |
218 | persistent_realloc (void *ptr, size_t size) |
216 | { |
219 | { |
217 | for (;;) |
220 | for (;;) |
… | |
… | |
255 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
258 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
256 | |
259 | |
257 | An event loop is described by a C<struct ev_loop *>. The library knows two |
260 | An event loop is described by a C<struct ev_loop *>. The library knows two |
258 | types of such loops, the I<default> loop, which supports signals and child |
261 | types of such loops, the I<default> loop, which supports signals and child |
259 | events, and dynamically created loops which do not. |
262 | events, and dynamically created loops which do not. |
260 | |
|
|
261 | If you use threads, a common model is to run the default event loop |
|
|
262 | in your main thread (or in a separate thread) and for each thread you |
|
|
263 | create, you also create another event loop. Libev itself does no locking |
|
|
264 | whatsoever, so if you mix calls to the same event loop in different |
|
|
265 | threads, make sure you lock (this is usually a bad idea, though, even if |
|
|
266 | done correctly, because it's hideous and inefficient). |
|
|
267 | |
263 | |
268 | =over 4 |
264 | =over 4 |
269 | |
265 | |
270 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
266 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
271 | |
267 | |
… | |
… | |
2382 | |
2378 | |
2383 | =item * Priorities are not currently supported. Initialising priorities |
2379 | =item * Priorities are not currently supported. Initialising priorities |
2384 | will fail and all watchers will have the same priority, even though there |
2380 | will fail and all watchers will have the same priority, even though there |
2385 | is an ev_pri field. |
2381 | is an ev_pri field. |
2386 | |
2382 | |
|
|
2383 | =item * In libevent, the last base created gets the signals, in libev, the |
|
|
2384 | first base created (== the default loop) gets the signals. |
|
|
2385 | |
2387 | =item * Other members are not supported. |
2386 | =item * Other members are not supported. |
2388 | |
2387 | |
2389 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
2388 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
2390 | to use the libev header file and library. |
2389 | to use the libev header file and library. |
2391 | |
2390 | |
… | |
… | |
2633 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
2632 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
2634 | |
2633 | |
2635 | Similar to the other two macros, this gives you the value of the default |
2634 | Similar to the other two macros, this gives you the value of the default |
2636 | loop, if multiple loops are supported ("ev loop default"). |
2635 | loop, if multiple loops are supported ("ev loop default"). |
2637 | |
2636 | |
|
|
2637 | =item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_> |
|
|
2638 | |
|
|
2639 | Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the |
|
|
2640 | default loop has been initialised (C<UC> == unchecked). Their behaviour |
|
|
2641 | is undefined when the default loop has not been initialised by a previous |
|
|
2642 | execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>. |
|
|
2643 | |
|
|
2644 | It is often prudent to use C<EV_DEFAULT> when initialising the first |
|
|
2645 | watcher in a function but use C<EV_DEFAULT_UC> afterwards. |
|
|
2646 | |
2638 | =back |
2647 | =back |
2639 | |
2648 | |
2640 | Example: Declare and initialise a check watcher, utilising the above |
2649 | Example: Declare and initialise a check watcher, utilising the above |
2641 | macros so it will work regardless of whether multiple loops are supported |
2650 | macros so it will work regardless of whether multiple loops are supported |
2642 | or not. |
2651 | or not. |
… | |
… | |
2737 | |
2746 | |
2738 | libev.m4 |
2747 | libev.m4 |
2739 | |
2748 | |
2740 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2749 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2741 | |
2750 | |
2742 | Libev can be configured via a variety of preprocessor symbols you have to define |
2751 | Libev can be configured via a variety of preprocessor symbols you have to |
2743 | before including any of its files. The default is not to build for multiplicity |
2752 | define before including any of its files. The default in the absense of |
2744 | and only include the select backend. |
2753 | autoconf is noted for every option. |
2745 | |
2754 | |
2746 | =over 4 |
2755 | =over 4 |
2747 | |
2756 | |
2748 | =item EV_STANDALONE |
2757 | =item EV_STANDALONE |
2749 | |
2758 | |
… | |
… | |
2775 | =item EV_USE_NANOSLEEP |
2784 | =item EV_USE_NANOSLEEP |
2776 | |
2785 | |
2777 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
2786 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
2778 | and will use it for delays. Otherwise it will use C<select ()>. |
2787 | and will use it for delays. Otherwise it will use C<select ()>. |
2779 | |
2788 | |
|
|
2789 | =item EV_USE_EVENTFD |
|
|
2790 | |
|
|
2791 | If defined to be C<1>, then libev will assume that C<eventfd ()> is |
|
|
2792 | available and will probe for kernel support at runtime. This will improve |
|
|
2793 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
|
|
2794 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
2795 | 2.7 or newer, otherwise disabled. |
|
|
2796 | |
2780 | =item EV_USE_SELECT |
2797 | =item EV_USE_SELECT |
2781 | |
2798 | |
2782 | If undefined or defined to be C<1>, libev will compile in support for the |
2799 | If undefined or defined to be C<1>, libev will compile in support for the |
2783 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2800 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2784 | other method takes over, select will be it. Otherwise the select backend |
2801 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
2820 | |
2837 | |
2821 | =item EV_USE_EPOLL |
2838 | =item EV_USE_EPOLL |
2822 | |
2839 | |
2823 | If defined to be C<1>, libev will compile in support for the Linux |
2840 | If defined to be C<1>, libev will compile in support for the Linux |
2824 | C<epoll>(7) backend. Its availability will be detected at runtime, |
2841 | C<epoll>(7) backend. Its availability will be detected at runtime, |
2825 | otherwise another method will be used as fallback. This is the |
2842 | otherwise another method will be used as fallback. This is the preferred |
2826 | preferred backend for GNU/Linux systems. |
2843 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
2844 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2827 | |
2845 | |
2828 | =item EV_USE_KQUEUE |
2846 | =item EV_USE_KQUEUE |
2829 | |
2847 | |
2830 | If defined to be C<1>, libev will compile in support for the BSD style |
2848 | If defined to be C<1>, libev will compile in support for the BSD style |
2831 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
2849 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
2850 | |
2868 | |
2851 | =item EV_USE_INOTIFY |
2869 | =item EV_USE_INOTIFY |
2852 | |
2870 | |
2853 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2871 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2854 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2872 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2855 | be detected at runtime. |
2873 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
2874 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2856 | |
2875 | |
2857 | =item EV_ATOMIC_T |
2876 | =item EV_ATOMIC_T |
2858 | |
2877 | |
2859 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
2878 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
2860 | access is atomic with respect to other threads or signal contexts. No such |
2879 | access is atomic with respect to other threads or signal contexts. No such |
… | |
… | |
3047 | |
3066 | |
3048 | #include "ev_cpp.h" |
3067 | #include "ev_cpp.h" |
3049 | #include "ev.c" |
3068 | #include "ev.c" |
3050 | |
3069 | |
3051 | |
3070 | |
|
|
3071 | =head1 THREADS AND COROUTINES |
|
|
3072 | |
|
|
3073 | =head2 THREADS |
|
|
3074 | |
|
|
3075 | Libev itself is completely threadsafe, but it uses no locking. This |
|
|
3076 | means that you can use as many loops as you want in parallel, as long as |
|
|
3077 | only one thread ever calls into one libev function with the same loop |
|
|
3078 | parameter. |
|
|
3079 | |
|
|
3080 | Or put differently: calls with different loop parameters can be done in |
|
|
3081 | parallel from multiple threads, calls with the same loop parameter must be |
|
|
3082 | done serially (but can be done from different threads, as long as only one |
|
|
3083 | thread ever is inside a call at any point in time, e.g. by using a mutex |
|
|
3084 | per loop). |
|
|
3085 | |
|
|
3086 | If you want to know which design is best for your problem, then I cannot |
|
|
3087 | help you but by giving some generic advice: |
|
|
3088 | |
|
|
3089 | =over 4 |
|
|
3090 | |
|
|
3091 | =item * most applications have a main thread: use the default libev loop |
|
|
3092 | in that thread, or create a seperate thread running only the default loop. |
|
|
3093 | |
|
|
3094 | This helps integrating other libraries or software modules that use libev |
|
|
3095 | themselves and don't care/know about threading. |
|
|
3096 | |
|
|
3097 | =item * one loop per thread is usually a good model. |
|
|
3098 | |
|
|
3099 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3100 | exists, but it is always a good start. |
|
|
3101 | |
|
|
3102 | =item * other models exist, such as the leader/follower pattern, where one |
|
|
3103 | loop is handed through multiple threads in a kind of round-robbin fashion. |
|
|
3104 | |
|
|
3105 | Chosing a model is hard - look around, learn, know that usually you cna do |
|
|
3106 | better than you currently do :-) |
|
|
3107 | |
|
|
3108 | =item * often you need to talk to some other thread which blocks in the |
|
|
3109 | event loop - C<ev_async> watchers can be used to wake them up from other |
|
|
3110 | threads safely (or from signal contexts...). |
|
|
3111 | |
|
|
3112 | =back |
|
|
3113 | |
|
|
3114 | =head2 COROUTINES |
|
|
3115 | |
|
|
3116 | Libev is much more accomodating to coroutines ("cooperative threads"): |
|
|
3117 | libev fully supports nesting calls to it's functions from different |
|
|
3118 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
|
|
3119 | different coroutines and switch freely between both coroutines running the |
|
|
3120 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3121 | you must not do this from C<ev_periodic> reschedule callbacks. |
|
|
3122 | |
|
|
3123 | Care has been invested into making sure that libev does not keep local |
|
|
3124 | state inside C<ev_loop>, and other calls do not usually allow coroutine |
|
|
3125 | switches. |
|
|
3126 | |
|
|
3127 | |
3052 | =head1 COMPLEXITIES |
3128 | =head1 COMPLEXITIES |
3053 | |
3129 | |
3054 | In this section the complexities of (many of) the algorithms used inside |
3130 | In this section the complexities of (many of) the algorithms used inside |
3055 | libev will be explained. For complexity discussions about backends see the |
3131 | libev will be explained. For complexity discussions about backends see the |
3056 | documentation for C<ev_default_init>. |
3132 | documentation for C<ev_default_init>. |