… | |
… | |
8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | // a single header file is required |
11 | // a single header file is required |
12 | #include <ev.h> |
12 | #include <ev.h> |
|
|
13 | |
|
|
14 | #include <stdio.h> // for puts |
13 | |
15 | |
14 | // every watcher type has its own typedef'd struct |
16 | // every watcher type has its own typedef'd struct |
15 | // with the name ev_TYPE |
17 | // with the name ev_TYPE |
16 | ev_io stdin_watcher; |
18 | ev_io stdin_watcher; |
17 | ev_timer timeout_watcher; |
19 | ev_timer timeout_watcher; |
… | |
… | |
41 | |
43 | |
42 | int |
44 | int |
43 | main (void) |
45 | main (void) |
44 | { |
46 | { |
45 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
46 | ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = ev_default_loop (0); |
47 | |
49 | |
48 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
49 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
51 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
418 | starting a watcher (without re-setting it) also usually doesn't cause |
420 | starting a watcher (without re-setting it) also usually doesn't cause |
419 | extra overhead. A fork can both result in spurious notifications as well |
421 | extra overhead. A fork can both result in spurious notifications as well |
420 | as in libev having to destroy and recreate the epoll object, which can |
422 | as in libev having to destroy and recreate the epoll object, which can |
421 | take considerable time and thus should be avoided. |
423 | take considerable time and thus should be avoided. |
422 | |
424 | |
|
|
425 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
|
|
426 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
427 | the usage. So sad. |
|
|
428 | |
423 | While nominally embeddable in other event loops, this feature is broken in |
429 | While nominally embeddable in other event loops, this feature is broken in |
424 | all kernel versions tested so far. |
430 | all kernel versions tested so far. |
425 | |
431 | |
426 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
432 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
427 | C<EVBACKEND_POLL>. |
433 | C<EVBACKEND_POLL>. |
… | |
… | |
454 | |
460 | |
455 | While nominally embeddable in other event loops, this doesn't work |
461 | While nominally embeddable in other event loops, this doesn't work |
456 | everywhere, so you might need to test for this. And since it is broken |
462 | everywhere, so you might need to test for this. And since it is broken |
457 | almost everywhere, you should only use it when you have a lot of sockets |
463 | almost everywhere, you should only use it when you have a lot of sockets |
458 | (for which it usually works), by embedding it into another event loop |
464 | (for which it usually works), by embedding it into another event loop |
459 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it, |
465 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course |
460 | using it only for sockets. |
466 | also broken on OS X)) and, did I mention it, using it only for sockets. |
461 | |
467 | |
462 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
468 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
463 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
469 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
464 | C<NOTE_EOF>. |
470 | C<NOTE_EOF>. |
465 | |
471 | |
… | |
… | |
1415 | else |
1421 | else |
1416 | { |
1422 | { |
1417 | // callback was invoked, but there was some activity, re-arm |
1423 | // callback was invoked, but there was some activity, re-arm |
1418 | // the watcher to fire in last_activity + 60, which is |
1424 | // the watcher to fire in last_activity + 60, which is |
1419 | // guaranteed to be in the future, so "again" is positive: |
1425 | // guaranteed to be in the future, so "again" is positive: |
1420 | w->again = timeout - now; |
1426 | w->repeat = timeout - now; |
1421 | ev_timer_again (EV_A_ w); |
1427 | ev_timer_again (EV_A_ w); |
1422 | } |
1428 | } |
1423 | } |
1429 | } |
1424 | |
1430 | |
1425 | To summarise the callback: first calculate the real timeout (defined |
1431 | To summarise the callback: first calculate the real timeout (defined |
… | |
… | |
2006 | the process. The exception are C<ev_stat> watchers - those call C<stat |
2012 | the process. The exception are C<ev_stat> watchers - those call C<stat |
2007 | ()>, which is a synchronous operation. |
2013 | ()>, which is a synchronous operation. |
2008 | |
2014 | |
2009 | For local paths, this usually doesn't matter: unless the system is very |
2015 | For local paths, this usually doesn't matter: unless the system is very |
2010 | busy or the intervals between stat's are large, a stat call will be fast, |
2016 | busy or the intervals between stat's are large, a stat call will be fast, |
2011 | as the path data is suually in memory already (except when starting the |
2017 | as the path data is usually in memory already (except when starting the |
2012 | watcher). |
2018 | watcher). |
2013 | |
2019 | |
2014 | For networked file systems, calling C<stat ()> can block an indefinite |
2020 | For networked file systems, calling C<stat ()> can block an indefinite |
2015 | time due to network issues, and even under good conditions, a stat call |
2021 | time due to network issues, and even under good conditions, a stat call |
2016 | often takes multiple milliseconds. |
2022 | often takes multiple milliseconds. |
… | |
… | |
2422 | some fds have to be watched and handled very quickly (with low latency), |
2428 | some fds have to be watched and handled very quickly (with low latency), |
2423 | and even priorities and idle watchers might have too much overhead. In |
2429 | and even priorities and idle watchers might have too much overhead. In |
2424 | this case you would put all the high priority stuff in one loop and all |
2430 | this case you would put all the high priority stuff in one loop and all |
2425 | the rest in a second one, and embed the second one in the first. |
2431 | the rest in a second one, and embed the second one in the first. |
2426 | |
2432 | |
2427 | As long as the watcher is active, the callback will be invoked every time |
2433 | As long as the watcher is active, the callback will be invoked every |
2428 | there might be events pending in the embedded loop. The callback must then |
2434 | time there might be events pending in the embedded loop. The callback |
2429 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2435 | must then call C<ev_embed_sweep (mainloop, watcher)> to make a single |
2430 | their callbacks (you could also start an idle watcher to give the embedded |
2436 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2431 | loop strictly lower priority for example). You can also set the callback |
2437 | C<ev_embed_sweep> function directly, it could also start an idle watcher |
2432 | to C<0>, in which case the embed watcher will automatically execute the |
2438 | to give the embedded loop strictly lower priority for example). |
2433 | embedded loop sweep. |
|
|
2434 | |
2439 | |
2435 | As long as the watcher is started it will automatically handle events. The |
2440 | You can also set the callback to C<0>, in which case the embed watcher |
2436 | callback will be invoked whenever some events have been handled. You can |
2441 | will automatically execute the embedded loop sweep whenever necessary. |
2437 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
2438 | interested in that. |
|
|
2439 | |
2442 | |
2440 | Also, there have not currently been made special provisions for forking: |
2443 | Fork detection will be handled transparently while the C<ev_embed> watcher |
2441 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2444 | is active, i.e., the embedded loop will automatically be forked when the |
2442 | but you will also have to stop and restart any C<ev_embed> watchers |
2445 | embedding loop forks. In other cases, the user is responsible for calling |
2443 | yourself - but you can use a fork watcher to handle this automatically, |
2446 | C<ev_loop_fork> on the embedded loop. |
2444 | and future versions of libev might do just that. |
|
|
2445 | |
2447 | |
2446 | Unfortunately, not all backends are embeddable: only the ones returned by |
2448 | Unfortunately, not all backends are embeddable: only the ones returned by |
2447 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2449 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2448 | portable one. |
2450 | portable one. |
2449 | |
2451 | |
… | |
… | |
2885 | |
2887 | |
2886 | myclass obj; |
2888 | myclass obj; |
2887 | ev::io iow; |
2889 | ev::io iow; |
2888 | iow.set <myclass, &myclass::io_cb> (&obj); |
2890 | iow.set <myclass, &myclass::io_cb> (&obj); |
2889 | |
2891 | |
|
|
2892 | =item w->set (object *) |
|
|
2893 | |
|
|
2894 | This is an B<experimental> feature that might go away in a future version. |
|
|
2895 | |
|
|
2896 | This is a variation of a method callback - leaving out the method to call |
|
|
2897 | will default the method to C<operator ()>, which makes it possible to use |
|
|
2898 | functor objects without having to manually specify the C<operator ()> all |
|
|
2899 | the time. Incidentally, you can then also leave out the template argument |
|
|
2900 | list. |
|
|
2901 | |
|
|
2902 | The C<operator ()> method prototype must be C<void operator ()(watcher &w, |
|
|
2903 | int revents)>. |
|
|
2904 | |
|
|
2905 | See the method-C<set> above for more details. |
|
|
2906 | |
|
|
2907 | Example: use a functor object as callback. |
|
|
2908 | |
|
|
2909 | struct myfunctor |
|
|
2910 | { |
|
|
2911 | void operator() (ev::io &w, int revents) |
|
|
2912 | { |
|
|
2913 | ... |
|
|
2914 | } |
|
|
2915 | } |
|
|
2916 | |
|
|
2917 | myfunctor f; |
|
|
2918 | |
|
|
2919 | ev::io w; |
|
|
2920 | w.set (&f); |
|
|
2921 | |
2890 | =item w->set<function> (void *data = 0) |
2922 | =item w->set<function> (void *data = 0) |
2891 | |
2923 | |
2892 | Also sets a callback, but uses a static method or plain function as |
2924 | Also sets a callback, but uses a static method or plain function as |
2893 | callback. The optional C<data> argument will be stored in the watcher's |
2925 | callback. The optional C<data> argument will be stored in the watcher's |
2894 | C<data> member and is free for you to use. |
2926 | C<data> member and is free for you to use. |
… | |
… | |
2993 | Tony Arcieri has written a ruby extension that offers access to a subset |
3025 | Tony Arcieri has written a ruby extension that offers access to a subset |
2994 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3026 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2995 | more on top of it. It can be found via gem servers. Its homepage is at |
3027 | more on top of it. It can be found via gem servers. Its homepage is at |
2996 | L<http://rev.rubyforge.org/>. |
3028 | L<http://rev.rubyforge.org/>. |
2997 | |
3029 | |
|
|
3030 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3031 | makes rev work even on mingw. |
|
|
3032 | |
2998 | =item D |
3033 | =item D |
2999 | |
3034 | |
3000 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3035 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3001 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3036 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3002 | |
3037 | |
… | |
… | |
3178 | keeps libev from including F<config.h>, and it also defines dummy |
3213 | keeps libev from including F<config.h>, and it also defines dummy |
3179 | implementations for some libevent functions (such as logging, which is not |
3214 | implementations for some libevent functions (such as logging, which is not |
3180 | supported). It will also not define any of the structs usually found in |
3215 | supported). It will also not define any of the structs usually found in |
3181 | F<event.h> that are not directly supported by the libev core alone. |
3216 | F<event.h> that are not directly supported by the libev core alone. |
3182 | |
3217 | |
|
|
3218 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3219 | configuration, but has to be more conservative. |
|
|
3220 | |
3183 | =item EV_USE_MONOTONIC |
3221 | =item EV_USE_MONOTONIC |
3184 | |
3222 | |
3185 | If defined to be C<1>, libev will try to detect the availability of the |
3223 | If defined to be C<1>, libev will try to detect the availability of the |
3186 | monotonic clock option at both compile time and runtime. Otherwise no use |
3224 | monotonic clock option at both compile time and runtime. Otherwise no |
3187 | of the monotonic clock option will be attempted. If you enable this, you |
3225 | use of the monotonic clock option will be attempted. If you enable this, |
3188 | usually have to link against librt or something similar. Enabling it when |
3226 | you usually have to link against librt or something similar. Enabling it |
3189 | the functionality isn't available is safe, though, although you have |
3227 | when the functionality isn't available is safe, though, although you have |
3190 | to make sure you link against any libraries where the C<clock_gettime> |
3228 | to make sure you link against any libraries where the C<clock_gettime> |
3191 | function is hiding in (often F<-lrt>). |
3229 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
3192 | |
3230 | |
3193 | =item EV_USE_REALTIME |
3231 | =item EV_USE_REALTIME |
3194 | |
3232 | |
3195 | If defined to be C<1>, libev will try to detect the availability of the |
3233 | If defined to be C<1>, libev will try to detect the availability of the |
3196 | real-time clock option at compile time (and assume its availability at |
3234 | real-time clock option at compile time (and assume its availability at |
3197 | runtime if successful). Otherwise no use of the real-time clock option will |
3235 | runtime if successful). Otherwise no use of the real-time clock option will |
3198 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3236 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3199 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3237 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3200 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3238 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3201 | |
3239 | |
|
|
3240 | =item EV_USE_CLOCK_SYSCALL |
|
|
3241 | |
|
|
3242 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3243 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3244 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3245 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3246 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3247 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3248 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3249 | higher, as it simplifies linking (no need for C<-lrt>). |
|
|
3250 | |
3202 | =item EV_USE_NANOSLEEP |
3251 | =item EV_USE_NANOSLEEP |
3203 | |
3252 | |
3204 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3253 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3205 | and will use it for delays. Otherwise it will use C<select ()>. |
3254 | and will use it for delays. Otherwise it will use C<select ()>. |
3206 | |
3255 | |
… | |
… | |
3221 | |
3270 | |
3222 | =item EV_SELECT_USE_FD_SET |
3271 | =item EV_SELECT_USE_FD_SET |
3223 | |
3272 | |
3224 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3273 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3225 | structure. This is useful if libev doesn't compile due to a missing |
3274 | structure. This is useful if libev doesn't compile due to a missing |
3226 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3275 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3227 | exotic systems. This usually limits the range of file descriptors to some |
3276 | on exotic systems. This usually limits the range of file descriptors to |
3228 | low limit such as 1024 or might have other limitations (winsocket only |
3277 | some low limit such as 1024 or might have other limitations (winsocket |
3229 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3278 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3230 | influence the size of the C<fd_set> used. |
3279 | configures the maximum size of the C<fd_set>. |
3231 | |
3280 | |
3232 | =item EV_SELECT_IS_WINSOCKET |
3281 | =item EV_SELECT_IS_WINSOCKET |
3233 | |
3282 | |
3234 | When defined to C<1>, the select backend will assume that |
3283 | When defined to C<1>, the select backend will assume that |
3235 | select/socket/connect etc. don't understand file descriptors but |
3284 | select/socket/connect etc. don't understand file descriptors but |