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Comparing libev/ev.pod (file contents):
Revision 1.213 by root, Wed Nov 5 02:48:45 2008 UTC vs.
Revision 1.220 by root, Thu Nov 20 11:25:15 2008 UTC

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);
418starting a watcher (without re-setting it) also usually doesn't cause 420starting a watcher (without re-setting it) also usually doesn't cause
419extra overhead. A fork can both result in spurious notifications as well 421extra overhead. A fork can both result in spurious notifications as well
420as in libev having to destroy and recreate the epoll object, which can 422as in libev having to destroy and recreate the epoll object, which can
421take considerable time and thus should be avoided. 423take considerable time and thus should be avoided.
422 424
423All this means that, in practise, C<EVBACKEND_SELECT> is as fast or faster 425All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or
424then epoll for maybe up to a hundred file descriptors. So sad. 426faster than epoll for maybe up to a hundred file descriptors, depending on
427the usage. So sad.
425 428
426While nominally embeddable in other event loops, this feature is broken in 429While nominally embeddable in other event loops, this feature is broken in
427all kernel versions tested so far. 430all kernel versions tested so far.
428 431
429This backend maps C<EV_READ> and C<EV_WRITE> in the same way as 432This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
1418 else 1421 else
1419 { 1422 {
1420 // callback was invoked, but there was some activity, re-arm 1423 // callback was invoked, but there was some activity, re-arm
1421 // the watcher to fire in last_activity + 60, which is 1424 // the watcher to fire in last_activity + 60, which is
1422 // guaranteed to be in the future, so "again" is positive: 1425 // guaranteed to be in the future, so "again" is positive:
1423 w->again = timeout - now; 1426 w->repeat = timeout - now;
1424 ev_timer_again (EV_A_ w); 1427 ev_timer_again (EV_A_ w);
1425 } 1428 }
1426 } 1429 }
1427 1430
1428To summarise the callback: first calculate the real timeout (defined 1431To summarise the callback: first calculate the real timeout (defined
2996Tony Arcieri has written a ruby extension that offers access to a subset 2999Tony Arcieri has written a ruby extension that offers access to a subset
2997of the libev API and adds file handle abstractions, asynchronous DNS and 3000of the libev API and adds file handle abstractions, asynchronous DNS and
2998more on top of it. It can be found via gem servers. Its homepage is at 3001more on top of it. It can be found via gem servers. Its homepage is at
2999L<http://rev.rubyforge.org/>. 3002L<http://rev.rubyforge.org/>.
3000 3003
3004Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190>
3005makes rev work even on mingw.
3006
3001=item D 3007=item D
3002 3008
3003Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to 3009Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
3004be found at L<http://proj.llucax.com.ar/wiki/evd>. 3010be found at L<http://proj.llucax.com.ar/wiki/evd>.
3005 3011
3181keeps libev from including F<config.h>, and it also defines dummy 3187keeps libev from including F<config.h>, and it also defines dummy
3182implementations for some libevent functions (such as logging, which is not 3188implementations for some libevent functions (such as logging, which is not
3183supported). It will also not define any of the structs usually found in 3189supported). It will also not define any of the structs usually found in
3184F<event.h> that are not directly supported by the libev core alone. 3190F<event.h> that are not directly supported by the libev core alone.
3185 3191
3192In stanbdalone mode, libev will still try to automatically deduce the
3193configuration, but has to be more conservative.
3194
3186=item EV_USE_MONOTONIC 3195=item EV_USE_MONOTONIC
3187 3196
3188If defined to be C<1>, libev will try to detect the availability of the 3197If defined to be C<1>, libev will try to detect the availability of the
3189monotonic clock option at both compile time and runtime. Otherwise no use 3198monotonic clock option at both compile time and runtime. Otherwise no
3190of the monotonic clock option will be attempted. If you enable this, you 3199use of the monotonic clock option will be attempted. If you enable this,
3191usually have to link against librt or something similar. Enabling it when 3200you usually have to link against librt or something similar. Enabling it
3192the functionality isn't available is safe, though, although you have 3201when the functionality isn't available is safe, though, although you have
3193to make sure you link against any libraries where the C<clock_gettime> 3202to make sure you link against any libraries where the C<clock_gettime>
3194function is hiding in (often F<-lrt>). 3203function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>.
3195 3204
3196=item EV_USE_REALTIME 3205=item EV_USE_REALTIME
3197 3206
3198If defined to be C<1>, libev will try to detect the availability of the 3207If defined to be C<1>, libev will try to detect the availability of the
3199real-time clock option at compile time (and assume its availability at 3208real-time clock option at compile time (and assume its availability at
3200runtime if successful). Otherwise no use of the real-time clock option will 3209runtime if successful). Otherwise no use of the real-time clock option will
3201be attempted. This effectively replaces C<gettimeofday> by C<clock_get 3210be attempted. This effectively replaces C<gettimeofday> by C<clock_get
3202(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the 3211(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
3203note about libraries in the description of C<EV_USE_MONOTONIC>, though. 3212note about libraries in the description of C<EV_USE_MONOTONIC>, though.
3204 3213
3214=item EV_USE_CLOCK_SYSCALL
3215
3216If defined to be C<1>, libev will try to use a direct syscall instead
3217of calling the system-provided C<clock_gettime> function. This option
3218exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt>
3219unconditionally pulls in C<libpthread>, slowing down single-threaded
3220programs needlessly. Using a direct syscall is slightly slower (in
3221theory), because no optimised vdso implementation can be used, but avoids
3222the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or
3223higher, as it simplifies linking (no need for C<-lrt>).
3224
3205=item EV_USE_NANOSLEEP 3225=item EV_USE_NANOSLEEP
3206 3226
3207If defined to be C<1>, libev will assume that C<nanosleep ()> is available 3227If defined to be C<1>, libev will assume that C<nanosleep ()> is available
3208and will use it for delays. Otherwise it will use C<select ()>. 3228and will use it for delays. Otherwise it will use C<select ()>.
3209 3229
3224 3244
3225=item EV_SELECT_USE_FD_SET 3245=item EV_SELECT_USE_FD_SET
3226 3246
3227If defined to C<1>, then the select backend will use the system C<fd_set> 3247If defined to C<1>, then the select backend will use the system C<fd_set>
3228structure. This is useful if libev doesn't compile due to a missing 3248structure. This is useful if libev doesn't compile due to a missing
3229C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on 3249C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout
3230exotic systems. This usually limits the range of file descriptors to some 3250on exotic systems. This usually limits the range of file descriptors to
3231low limit such as 1024 or might have other limitations (winsocket only 3251some low limit such as 1024 or might have other limitations (winsocket
3232allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might 3252only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation,
3233influence the size of the C<fd_set> used. 3253configures the maximum size of the C<fd_set>.
3234 3254
3235=item EV_SELECT_IS_WINSOCKET 3255=item EV_SELECT_IS_WINSOCKET
3236 3256
3237When defined to C<1>, the select backend will assume that 3257When defined to C<1>, the select backend will assume that
3238select/socket/connect etc. don't understand file descriptors but 3258select/socket/connect etc. don't understand file descriptors but

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