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Comparing libev/ev.pod (file contents):
Revision 1.212 by root, Mon Nov 3 15:13:53 2008 UTC vs.
Revision 1.219 by root, Thu Nov 20 00:43:58 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;
417i.e. keep at least one watcher active per fd at all times. Stopping and 419i.e. keep at least one watcher active per fd at all times. Stopping and
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.
424
425All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or
426faster than epoll for maybe up to a hundred file descriptors, depending on
427the usage. So sad.
422 428
423While nominally embeddable in other event loops, this feature is broken in 429While nominally embeddable in other event loops, this feature is broken in
424all kernel versions tested so far. 430all kernel versions tested so far.
425 431
426This 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
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
1425To summarise the callback: first calculate the real timeout (defined 1431To summarise the callback: first calculate the real timeout (defined
2993Tony 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
2994of the libev API and adds file handle abstractions, asynchronous DNS and 3000of the libev API and adds file handle abstractions, asynchronous DNS and
2995more 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
2996L<http://rev.rubyforge.org/>. 3002L<http://rev.rubyforge.org/>.
2997 3003
3004Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190>
3005makes rev work even on mingw.
3006
2998=item D 3007=item D
2999 3008
3000Leandro 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
3001be found at L<http://proj.llucax.com.ar/wiki/evd>. 3010be found at L<http://proj.llucax.com.ar/wiki/evd>.
3002 3011
3178keeps libev from including F<config.h>, and it also defines dummy 3187keeps libev from including F<config.h>, and it also defines dummy
3179implementations for some libevent functions (such as logging, which is not 3188implementations for some libevent functions (such as logging, which is not
3180supported). 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
3181F<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.
3182 3191
3192In stanbdalone mode, libev will still try to automatically deduce the
3193configuration, but has to be more conservative.
3194
3183=item EV_USE_MONOTONIC 3195=item EV_USE_MONOTONIC
3184 3196
3185If 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
3186monotonic clock option at both compile time and runtime. Otherwise no use 3198monotonic clock option at both compile time and runtime. Otherwise no
3187of 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,
3188usually have to link against librt or something similar. Enabling it when 3200you usually have to link against librt or something similar. Enabling it
3189the functionality isn't available is safe, though, although you have 3201when the functionality isn't available is safe, though, although you have
3190to 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>
3191function is hiding in (often F<-lrt>). 3203function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>.
3192 3204
3193=item EV_USE_REALTIME 3205=item EV_USE_REALTIME
3194 3206
3195If 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
3196real-time clock option at compile time (and assume its availability at 3208real-time clock option at compile time (and assume its availability at
3197runtime 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
3198be attempted. This effectively replaces C<gettimeofday> by C<clock_get 3210be attempted. This effectively replaces C<gettimeofday> by C<clock_get
3199(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the 3211(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
3200note about libraries in the description of C<EV_USE_MONOTONIC>, though. 3212note about libraries in the description of C<EV_USE_MONOTONIC>, though.
3201 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
3202=item EV_USE_NANOSLEEP 3225=item EV_USE_NANOSLEEP
3203 3226
3204If 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
3205and will use it for delays. Otherwise it will use C<select ()>. 3228and will use it for delays. Otherwise it will use C<select ()>.
3206 3229
3221 3244
3222=item EV_SELECT_USE_FD_SET 3245=item EV_SELECT_USE_FD_SET
3223 3246
3224If 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>
3225structure. 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
3226C<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
3227exotic systems. This usually limits the range of file descriptors to some 3250on exotic systems. This usually limits the range of file descriptors to
3228low limit such as 1024 or might have other limitations (winsocket only 3251some low limit such as 1024 or might have other limitations (winsocket
3229allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might 3252only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation,
3230influence the size of the C<fd_set> used. 3253configures the maximum size of the C<fd_set>.
3231 3254
3232=item EV_SELECT_IS_WINSOCKET 3255=item EV_SELECT_IS_WINSOCKET
3233 3256
3234When defined to C<1>, the select backend will assume that 3257When defined to C<1>, the select backend will assume that
3235select/socket/connect etc. don't understand file descriptors but 3258select/socket/connect etc. don't understand file descriptors but

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