ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/libev/ev.pod
(Generate patch)

Comparing libev/ev.pod (file contents):
Revision 1.115 by root, Mon Dec 31 01:32:59 2007 UTC vs.
Revision 1.121 by root, Mon Jan 28 12:13:54 2008 UTC

260flags. If that is troubling you, check C<ev_backend ()> afterwards). 260flags. If that is troubling you, check C<ev_backend ()> afterwards).
261 261
262If you don't know what event loop to use, use the one returned from this 262If you don't know what event loop to use, use the one returned from this
263function. 263function.
264 264
265The default loop is the only loop that can handle C<ev_signal> and
266C<ev_child> watchers, and to do this, it always registers a handler
267for C<SIGCHLD>. If this is a problem for your app you can either
268create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
269can simply overwrite the C<SIGCHLD> signal handler I<after> calling
270C<ev_default_init>.
271
265The flags argument can be used to specify special behaviour or specific 272The flags argument can be used to specify special behaviour or specific
266backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). 273backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
267 274
268The following flags are supported: 275The following flags are supported:
269 276
403While this backend scales well, it requires one system call per active 410While this backend scales well, it requires one system call per active
404file descriptor per loop iteration. For small and medium numbers of file 411file descriptor per loop iteration. For small and medium numbers of file
405descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend 412descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
406might perform better. 413might perform better.
407 414
415On the positive side, ignoring the spurious readyness notifications, this
416backend actually performed to specification in all tests and is fully
417embeddable, which is a rare feat among the OS-specific backends.
418
408=item C<EVBACKEND_ALL> 419=item C<EVBACKEND_ALL>
409 420
410Try all backends (even potentially broken ones that wouldn't be tried 421Try all backends (even potentially broken ones that wouldn't be tried
411with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as 422with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
412C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. 423C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
414It is definitely not recommended to use this flag. 425It is definitely not recommended to use this flag.
415 426
416=back 427=back
417 428
418If one or more of these are ored into the flags value, then only these 429If one or more of these are ored into the flags value, then only these
419backends will be tried (in the reverse order as given here). If none are 430backends will be tried (in the reverse order as listed here). If none are
420specified, most compiled-in backend will be tried, usually in reverse 431specified, all backends in C<ev_recommended_backends ()> will be tried.
421order of their flag values :)
422 432
423The most typical usage is like this: 433The most typical usage is like this:
424 434
425 if (!ev_default_loop (0)) 435 if (!ev_default_loop (0))
426 fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); 436 fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
473Like C<ev_default_destroy>, but destroys an event loop created by an 483Like C<ev_default_destroy>, but destroys an event loop created by an
474earlier call to C<ev_loop_new>. 484earlier call to C<ev_loop_new>.
475 485
476=item ev_default_fork () 486=item ev_default_fork ()
477 487
488This function sets a flag that causes subsequent C<ev_loop> iterations
478This function reinitialises the kernel state for backends that have 489to reinitialise the kernel state for backends that have one. Despite the
479one. Despite the name, you can call it anytime, but it makes most sense 490name, you can call it anytime, but it makes most sense after forking, in
480after forking, in either the parent or child process (or both, but that 491the child process (or both child and parent, but that again makes little
481again makes little sense). 492sense). You I<must> call it in the child before using any of the libev
493functions, and it will only take effect at the next C<ev_loop> iteration.
482 494
483You I<must> call this function in the child process after forking if and 495On the other hand, you only need to call this function in the child
484only if you want to use the event library in both processes. If you just 496process if and only if you want to use the event library in the child. If
485fork+exec, you don't have to call it. 497you just fork+exec, you don't have to call it at all.
486 498
487The function itself is quite fast and it's usually not a problem to call 499The function itself is quite fast and it's usually not a problem to call
488it just in case after a fork. To make this easy, the function will fit in 500it just in case after a fork. To make this easy, the function will fit in
489quite nicely into a call to C<pthread_atfork>: 501quite nicely into a call to C<pthread_atfork>:
490 502
491 pthread_atfork (0, 0, ev_default_fork); 503 pthread_atfork (0, 0, ev_default_fork);
492
493At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
494without calling this function, so if you force one of those backends you
495do not need to care.
496 504
497=item ev_loop_fork (loop) 505=item ev_loop_fork (loop)
498 506
499Like C<ev_default_fork>, but acts on an event loop created by 507Like C<ev_default_fork>, but acts on an event loop created by
500C<ev_loop_new>. Yes, you have to call this on every allocated event loop 508C<ev_loop_new>. Yes, you have to call this on every allocated event loop
605returning, ev_unref() after starting, and ev_ref() before stopping it. For 613returning, ev_unref() after starting, and ev_ref() before stopping it. For
606example, libev itself uses this for its internal signal pipe: It is not 614example, libev itself uses this for its internal signal pipe: It is not
607visible to the libev user and should not keep C<ev_loop> from exiting if 615visible to the libev user and should not keep C<ev_loop> from exiting if
608no event watchers registered by it are active. It is also an excellent 616no event watchers registered by it are active. It is also an excellent
609way to do this for generic recurring timers or from within third-party 617way to do this for generic recurring timers or from within third-party
610libraries. Just remember to I<unref after start> and I<ref before stop>. 618libraries. Just remember to I<unref after start> and I<ref before stop>
619(but only if the watcher wasn't active before, or was active before,
620respectively).
611 621
612Example: Create a signal watcher, but keep it from keeping C<ev_loop> 622Example: Create a signal watcher, but keep it from keeping C<ev_loop>
613running when nothing else is active. 623running when nothing else is active.
614 624
615 struct ev_signal exitsig; 625 struct ev_signal exitsig;
1428 1438
1429=head3 Watcher-Specific Functions and Data Members 1439=head3 Watcher-Specific Functions and Data Members
1430 1440
1431=over 4 1441=over 4
1432 1442
1433=item ev_child_init (ev_child *, callback, int pid) 1443=item ev_child_init (ev_child *, callback, int pid, int trace)
1434 1444
1435=item ev_child_set (ev_child *, int pid) 1445=item ev_child_set (ev_child *, int pid, int trace)
1436 1446
1437Configures the watcher to wait for status changes of process C<pid> (or 1447Configures the watcher to wait for status changes of process C<pid> (or
1438I<any> process if C<pid> is specified as C<0>). The callback can look 1448I<any> process if C<pid> is specified as C<0>). The callback can look
1439at the C<rstatus> member of the C<ev_child> watcher structure to see 1449at the C<rstatus> member of the C<ev_child> watcher structure to see
1440the status word (use the macros from C<sys/wait.h> and see your systems 1450the status word (use the macros from C<sys/wait.h> and see your systems
1441C<waitpid> documentation). The C<rpid> member contains the pid of the 1451C<waitpid> documentation). The C<rpid> member contains the pid of the
1442process causing the status change. 1452process causing the status change. C<trace> must be either C<0> (only
1453activate the watcher when the process terminates) or C<1> (additionally
1454activate the watcher when the process is stopped or continued).
1443 1455
1444=item int pid [read-only] 1456=item int pid [read-only]
1445 1457
1446The process id this watcher watches out for, or C<0>, meaning any process id. 1458The process id this watcher watches out for, or C<0>, meaning any process id.
1447 1459
1683 static void 1695 static void
1684 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1696 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1685 { 1697 {
1686 free (w); 1698 free (w);
1687 // now do something you wanted to do when the program has 1699 // now do something you wanted to do when the program has
1688 // no longer asnything immediate to do. 1700 // no longer anything immediate to do.
1689 } 1701 }
1690 1702
1691 struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); 1703 struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1692 ev_idle_init (idle_watcher, idle_cb); 1704 ev_idle_init (idle_watcher, idle_cb);
1693 ev_idle_start (loop, idle_cb); 1705 ev_idle_start (loop, idle_cb);
2270Example: Define a class with an IO and idle watcher, start one of them in 2282Example: Define a class with an IO and idle watcher, start one of them in
2271the constructor. 2283the constructor.
2272 2284
2273 class myclass 2285 class myclass
2274 { 2286 {
2275 ev_io io; void io_cb (ev::io &w, int revents); 2287 ev::io io; void io_cb (ev::io &w, int revents);
2276 ev_idle idle void idle_cb (ev::idle &w, int revents); 2288 ev:idle idle void idle_cb (ev::idle &w, int revents);
2277 2289
2278 myclass (); 2290 myclass (int fd)
2279 }
2280
2281 myclass::myclass (int fd)
2282 { 2291 {
2283 io .set <myclass, &myclass::io_cb > (this); 2292 io .set <myclass, &myclass::io_cb > (this);
2284 idle.set <myclass, &myclass::idle_cb> (this); 2293 idle.set <myclass, &myclass::idle_cb> (this);
2285 2294
2286 io.start (fd, ev::READ); 2295 io.start (fd, ev::READ);
2296 }
2287 } 2297 };
2288 2298
2289 2299
2290=head1 MACRO MAGIC 2300=head1 MACRO MAGIC
2291 2301
2292Libev can be compiled with a variety of options, the most fundamantal 2302Libev can be compiled with a variety of options, the most fundamantal
2551be detected at runtime. 2561be detected at runtime.
2552 2562
2553=item EV_H 2563=item EV_H
2554 2564
2555The name of the F<ev.h> header file used to include it. The default if 2565The name of the F<ev.h> header file used to include it. The default if
2556undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to 2566undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
2557virtually rename the F<ev.h> header file in case of conflicts. 2567used to virtually rename the F<ev.h> header file in case of conflicts.
2558 2568
2559=item EV_CONFIG_H 2569=item EV_CONFIG_H
2560 2570
2561If C<EV_STANDALONE> isn't C<1>, this variable can be used to override 2571If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
2562F<ev.c>'s idea of where to find the F<config.h> file, similarly to 2572F<ev.c>'s idea of where to find the F<config.h> file, similarly to
2563C<EV_H>, above. 2573C<EV_H>, above.
2564 2574
2565=item EV_EVENT_H 2575=item EV_EVENT_H
2566 2576
2567Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea 2577Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
2568of how the F<event.h> header can be found, the dfeault is C<"event.h">. 2578of how the F<event.h> header can be found, the default is C<"event.h">.
2569 2579
2570=item EV_PROTOTYPES 2580=item EV_PROTOTYPES
2571 2581
2572If defined to be C<0>, then F<ev.h> will not define any function 2582If defined to be C<0>, then F<ev.h> will not define any function
2573prototypes, but still define all the structs and other symbols. This is 2583prototypes, but still define all the structs and other symbols. This is

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines