… | |
… | |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
|
|
11 | // a single header file is required |
11 | #include <ev.h> |
12 | #include <ev.h> |
12 | |
13 | |
|
|
14 | // every watcher type has its own typedef'd struct |
|
|
15 | // with the name ev_<type> |
13 | ev_io stdin_watcher; |
16 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
17 | ev_timer timeout_watcher; |
15 | |
18 | |
|
|
19 | // all watcher callbacks have a similar signature |
16 | /* called when data readable on stdin */ |
20 | // this callback is called when data is readable on stdin |
17 | static void |
21 | static void |
18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
19 | { |
23 | { |
20 | /* puts ("stdin ready"); */ |
24 | puts ("stdin ready"); |
21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
25 | // for one-shot events, one must manually stop the watcher |
22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
26 | // with its corresponding stop function. |
|
|
27 | ev_io_stop (EV_A_ w); |
|
|
28 | |
|
|
29 | // this causes all nested ev_loop's to stop iterating |
|
|
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
23 | } |
31 | } |
24 | |
32 | |
|
|
33 | // another callback, this time for a time-out |
25 | static void |
34 | static void |
26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
35 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
27 | { |
36 | { |
28 | /* puts ("timeout"); */ |
37 | puts ("timeout"); |
29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
38 | // this causes the innermost ev_loop to stop iterating |
|
|
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
30 | } |
40 | } |
31 | |
41 | |
32 | int |
42 | int |
33 | main (void) |
43 | main (void) |
34 | { |
44 | { |
|
|
45 | // use the default event loop unless you have special needs |
35 | struct ev_loop *loop = ev_default_loop (0); |
46 | struct ev_loop *loop = ev_default_loop (0); |
36 | |
47 | |
37 | /* initialise an io watcher, then start it */ |
48 | // initialise an io watcher, then start it |
|
|
49 | // this one will watch for stdin to become readable |
38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
39 | ev_io_start (loop, &stdin_watcher); |
51 | ev_io_start (loop, &stdin_watcher); |
40 | |
52 | |
|
|
53 | // initialise a timer watcher, then start it |
41 | /* simple non-repeating 5.5 second timeout */ |
54 | // simple non-repeating 5.5 second timeout |
42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
43 | ev_timer_start (loop, &timeout_watcher); |
56 | ev_timer_start (loop, &timeout_watcher); |
44 | |
57 | |
45 | /* loop till timeout or data ready */ |
58 | // now wait for events to arrive |
46 | ev_loop (loop, 0); |
59 | ev_loop (loop, 0); |
47 | |
60 | |
|
|
61 | // unloop was called, so exit |
48 | return 0; |
62 | return 0; |
49 | } |
63 | } |
50 | |
64 | |
51 | =head1 DESCRIPTION |
65 | =head1 DESCRIPTION |
52 | |
66 | |
53 | The newest version of this document is also available as a html-formatted |
67 | The newest version of this document is also available as an html-formatted |
54 | web page you might find easier to navigate when reading it for the first |
68 | web page you might find easier to navigate when reading it for the first |
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
69 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
56 | |
70 | |
57 | Libev is an event loop: you register interest in certain events (such as a |
71 | Libev is an event loop: you register interest in certain events (such as a |
58 | file descriptor being readable or a timeout occurring), and it will manage |
72 | file descriptor being readable or a timeout occurring), and it will manage |
… | |
… | |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
98 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
85 | for example). |
99 | for example). |
86 | |
100 | |
87 | =head2 CONVENTIONS |
101 | =head2 CONVENTIONS |
88 | |
102 | |
89 | Libev is very configurable. In this manual the default configuration will |
103 | Libev is very configurable. In this manual the default (and most common) |
90 | be described, which supports multiple event loops. For more info about |
104 | configuration will be described, which supports multiple event loops. For |
91 | various configuration options please have a look at B<EMBED> section in |
105 | more info about various configuration options please have a look at |
92 | this manual. If libev was configured without support for multiple event |
106 | B<EMBED> section in this manual. If libev was configured without support |
93 | loops, then all functions taking an initial argument of name C<loop> |
107 | for multiple event loops, then all functions taking an initial argument of |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
108 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
|
|
109 | this argument. |
95 | |
110 | |
96 | =head2 TIME REPRESENTATION |
111 | =head2 TIME REPRESENTATION |
97 | |
112 | |
98 | Libev represents time as a single floating point number, representing the |
113 | Libev represents time as a single floating point number, representing the |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
… | |
… | |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
275 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
261 | |
276 | |
262 | If you don't know what event loop to use, use the one returned from this |
277 | If you don't know what event loop to use, use the one returned from this |
263 | function. |
278 | function. |
264 | |
279 | |
|
|
280 | The default loop is the only loop that can handle C<ev_signal> and |
|
|
281 | C<ev_child> watchers, and to do this, it always registers a handler |
|
|
282 | for C<SIGCHLD>. If this is a problem for your app you can either |
|
|
283 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
|
|
284 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
|
|
285 | C<ev_default_init>. |
|
|
286 | |
265 | The flags argument can be used to specify special behaviour or specific |
287 | The flags argument can be used to specify special behaviour or specific |
266 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
288 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
267 | |
289 | |
268 | The following flags are supported: |
290 | The following flags are supported: |
269 | |
291 | |
… | |
… | |
290 | enabling this flag. |
312 | enabling this flag. |
291 | |
313 | |
292 | This works by calling C<getpid ()> on every iteration of the loop, |
314 | This works by calling C<getpid ()> on every iteration of the loop, |
293 | and thus this might slow down your event loop if you do a lot of loop |
315 | and thus this might slow down your event loop if you do a lot of loop |
294 | iterations and little real work, but is usually not noticeable (on my |
316 | iterations and little real work, but is usually not noticeable (on my |
295 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
317 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
296 | without a syscall and thus I<very> fast, but my Linux system also has |
318 | without a syscall and thus I<very> fast, but my GNU/Linux system also has |
297 | C<pthread_atfork> which is even faster). |
319 | C<pthread_atfork> which is even faster). |
298 | |
320 | |
299 | The big advantage of this flag is that you can forget about fork (and |
321 | The big advantage of this flag is that you can forget about fork (and |
300 | forget about forgetting to tell libev about forking) when you use this |
322 | forget about forgetting to tell libev about forking) when you use this |
301 | flag. |
323 | flag. |
… | |
… | |
403 | While this backend scales well, it requires one system call per active |
425 | While this backend scales well, it requires one system call per active |
404 | file descriptor per loop iteration. For small and medium numbers of file |
426 | file descriptor per loop iteration. For small and medium numbers of file |
405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
427 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
406 | might perform better. |
428 | might perform better. |
407 | |
429 | |
|
|
430 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
431 | backend actually performed to specification in all tests and is fully |
|
|
432 | embeddable, which is a rare feat among the OS-specific backends. |
|
|
433 | |
408 | =item C<EVBACKEND_ALL> |
434 | =item C<EVBACKEND_ALL> |
409 | |
435 | |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
436 | Try all backends (even potentially broken ones that wouldn't be tried |
411 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
437 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
438 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
… | |
… | |
414 | It is definitely not recommended to use this flag. |
440 | It is definitely not recommended to use this flag. |
415 | |
441 | |
416 | =back |
442 | =back |
417 | |
443 | |
418 | If one or more of these are ored into the flags value, then only these |
444 | If one or more of these are ored into the flags value, then only these |
419 | backends will be tried (in the reverse order as given here). If none are |
445 | backends will be tried (in the reverse order as listed here). If none are |
420 | specified, most compiled-in backend will be tried, usually in reverse |
446 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
421 | order of their flag values :) |
|
|
422 | |
447 | |
423 | The most typical usage is like this: |
448 | The most typical usage is like this: |
424 | |
449 | |
425 | if (!ev_default_loop (0)) |
450 | if (!ev_default_loop (0)) |
426 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
451 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
473 | Like C<ev_default_destroy>, but destroys an event loop created by an |
498 | Like C<ev_default_destroy>, but destroys an event loop created by an |
474 | earlier call to C<ev_loop_new>. |
499 | earlier call to C<ev_loop_new>. |
475 | |
500 | |
476 | =item ev_default_fork () |
501 | =item ev_default_fork () |
477 | |
502 | |
|
|
503 | This function sets a flag that causes subsequent C<ev_loop> iterations |
478 | This function reinitialises the kernel state for backends that have |
504 | to reinitialise the kernel state for backends that have one. Despite the |
479 | one. Despite the name, you can call it anytime, but it makes most sense |
505 | name, you can call it anytime, but it makes most sense after forking, in |
480 | after forking, in either the parent or child process (or both, but that |
506 | the child process (or both child and parent, but that again makes little |
481 | again makes little sense). |
507 | sense). You I<must> call it in the child before using any of the libev |
|
|
508 | functions, and it will only take effect at the next C<ev_loop> iteration. |
482 | |
509 | |
483 | You I<must> call this function in the child process after forking if and |
510 | On the other hand, you only need to call this function in the child |
484 | only if you want to use the event library in both processes. If you just |
511 | process if and only if you want to use the event library in the child. If |
485 | fork+exec, you don't have to call it. |
512 | you just fork+exec, you don't have to call it at all. |
486 | |
513 | |
487 | The function itself is quite fast and it's usually not a problem to call |
514 | The function itself is quite fast and it's usually not a problem to call |
488 | it just in case after a fork. To make this easy, the function will fit in |
515 | it just in case after a fork. To make this easy, the function will fit in |
489 | quite nicely into a call to C<pthread_atfork>: |
516 | quite nicely into a call to C<pthread_atfork>: |
490 | |
517 | |
491 | pthread_atfork (0, 0, ev_default_fork); |
518 | pthread_atfork (0, 0, ev_default_fork); |
492 | |
519 | |
493 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
494 | without calling this function, so if you force one of those backends you |
|
|
495 | do not need to care. |
|
|
496 | |
|
|
497 | =item ev_loop_fork (loop) |
520 | =item ev_loop_fork (loop) |
498 | |
521 | |
499 | Like C<ev_default_fork>, but acts on an event loop created by |
522 | Like C<ev_default_fork>, but acts on an event loop created by |
500 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
523 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
501 | after fork, and how you do this is entirely your own problem. |
524 | after fork, and how you do this is entirely your own problem. |
|
|
525 | |
|
|
526 | =item int ev_is_default_loop (loop) |
|
|
527 | |
|
|
528 | Returns true when the given loop actually is the default loop, false otherwise. |
502 | |
529 | |
503 | =item unsigned int ev_loop_count (loop) |
530 | =item unsigned int ev_loop_count (loop) |
504 | |
531 | |
505 | Returns the count of loop iterations for the loop, which is identical to |
532 | Returns the count of loop iterations for the loop, which is identical to |
506 | the number of times libev did poll for new events. It starts at C<0> and |
533 | the number of times libev did poll for new events. It starts at C<0> and |
… | |
… | |
766 | =item C<EV_FORK> |
793 | =item C<EV_FORK> |
767 | |
794 | |
768 | The event loop has been resumed in the child process after fork (see |
795 | The event loop has been resumed in the child process after fork (see |
769 | C<ev_fork>). |
796 | C<ev_fork>). |
770 | |
797 | |
|
|
798 | =item C<EV_ASYNC> |
|
|
799 | |
|
|
800 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
801 | |
771 | =item C<EV_ERROR> |
802 | =item C<EV_ERROR> |
772 | |
803 | |
773 | An unspecified error has occured, the watcher has been stopped. This might |
804 | An unspecified error has occured, the watcher has been stopped. This might |
774 | happen because the watcher could not be properly started because libev |
805 | happen because the watcher could not be properly started because libev |
775 | ran out of memory, a file descriptor was found to be closed or any other |
806 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
1140 | configure a timer to trigger every 10 seconds, then it will trigger at |
1171 | configure a timer to trigger every 10 seconds, then it will trigger at |
1141 | exactly 10 second intervals. If, however, your program cannot keep up with |
1172 | exactly 10 second intervals. If, however, your program cannot keep up with |
1142 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1173 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1143 | timer will not fire more than once per event loop iteration. |
1174 | timer will not fire more than once per event loop iteration. |
1144 | |
1175 | |
1145 | =item ev_timer_again (loop) |
1176 | =item ev_timer_again (loop, ev_timer *) |
1146 | |
1177 | |
1147 | This will act as if the timer timed out and restart it again if it is |
1178 | This will act as if the timer timed out and restart it again if it is |
1148 | repeating. The exact semantics are: |
1179 | repeating. The exact semantics are: |
1149 | |
1180 | |
1150 | If the timer is pending, its pending status is cleared. |
1181 | If the timer is pending, its pending status is cleared. |
… | |
… | |
1259 | In this configuration the watcher triggers an event at the wallclock time |
1290 | In this configuration the watcher triggers an event at the wallclock time |
1260 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1291 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1261 | that is, if it is to be run at January 1st 2011 then it will run when the |
1292 | that is, if it is to be run at January 1st 2011 then it will run when the |
1262 | system time reaches or surpasses this time. |
1293 | system time reaches or surpasses this time. |
1263 | |
1294 | |
1264 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1295 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1265 | |
1296 | |
1266 | In this mode the watcher will always be scheduled to time out at the next |
1297 | In this mode the watcher will always be scheduled to time out at the next |
1267 | C<at + N * interval> time (for some integer N, which can also be negative) |
1298 | C<at + N * interval> time (for some integer N, which can also be negative) |
1268 | and then repeat, regardless of any time jumps. |
1299 | and then repeat, regardless of any time jumps. |
1269 | |
1300 | |
… | |
… | |
1403 | with the kernel (thus it coexists with your own signal handlers as long |
1434 | with the kernel (thus it coexists with your own signal handlers as long |
1404 | as you don't register any with libev). Similarly, when the last signal |
1435 | as you don't register any with libev). Similarly, when the last signal |
1405 | watcher for a signal is stopped libev will reset the signal handler to |
1436 | watcher for a signal is stopped libev will reset the signal handler to |
1406 | SIG_DFL (regardless of what it was set to before). |
1437 | SIG_DFL (regardless of what it was set to before). |
1407 | |
1438 | |
|
|
1439 | If possible and supported, libev will install its handlers with |
|
|
1440 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
|
|
1441 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1442 | signals you can block all signals in an C<ev_check> watcher and unblock |
|
|
1443 | them in an C<ev_prepare> watcher. |
|
|
1444 | |
1408 | =head3 Watcher-Specific Functions and Data Members |
1445 | =head3 Watcher-Specific Functions and Data Members |
1409 | |
1446 | |
1410 | =over 4 |
1447 | =over 4 |
1411 | |
1448 | |
1412 | =item ev_signal_init (ev_signal *, callback, int signum) |
1449 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
1420 | |
1457 | |
1421 | The signal the watcher watches out for. |
1458 | The signal the watcher watches out for. |
1422 | |
1459 | |
1423 | =back |
1460 | =back |
1424 | |
1461 | |
|
|
1462 | =head3 Examples |
|
|
1463 | |
|
|
1464 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1465 | |
|
|
1466 | static void |
|
|
1467 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1468 | { |
|
|
1469 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1470 | } |
|
|
1471 | |
|
|
1472 | struct ev_signal signal_watcher; |
|
|
1473 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1474 | ev_signal_start (loop, &sigint_cb); |
|
|
1475 | |
1425 | |
1476 | |
1426 | =head2 C<ev_child> - watch out for process status changes |
1477 | =head2 C<ev_child> - watch out for process status changes |
1427 | |
1478 | |
1428 | Child watchers trigger when your process receives a SIGCHLD in response to |
1479 | Child watchers trigger when your process receives a SIGCHLD in response to |
1429 | some child status changes (most typically when a child of yours dies). |
1480 | some child status changes (most typically when a child of yours dies). It |
|
|
1481 | is permissible to install a child watcher I<after> the child has been |
|
|
1482 | forked (which implies it might have already exited), as long as the event |
|
|
1483 | loop isn't entered (or is continued from a watcher). |
|
|
1484 | |
|
|
1485 | Only the default event loop is capable of handling signals, and therefore |
|
|
1486 | you can only rgeister child watchers in the default event loop. |
|
|
1487 | |
|
|
1488 | =head3 Process Interaction |
|
|
1489 | |
|
|
1490 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
|
|
1491 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1492 | the first child watcher is started after the child exits. The occurance |
|
|
1493 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
|
|
1494 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1495 | children, even ones not watched. |
|
|
1496 | |
|
|
1497 | =head3 Overriding the Built-In Processing |
|
|
1498 | |
|
|
1499 | Libev offers no special support for overriding the built-in child |
|
|
1500 | processing, but if your application collides with libev's default child |
|
|
1501 | handler, you can override it easily by installing your own handler for |
|
|
1502 | C<SIGCHLD> after initialising the default loop, and making sure the |
|
|
1503 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1504 | event-based approach to child reaping and thus use libev's support for |
|
|
1505 | that, so other libev users can use C<ev_child> watchers freely. |
1430 | |
1506 | |
1431 | =head3 Watcher-Specific Functions and Data Members |
1507 | =head3 Watcher-Specific Functions and Data Members |
1432 | |
1508 | |
1433 | =over 4 |
1509 | =over 4 |
1434 | |
1510 | |
1435 | =item ev_child_init (ev_child *, callback, int pid) |
1511 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1436 | |
1512 | |
1437 | =item ev_child_set (ev_child *, int pid) |
1513 | =item ev_child_set (ev_child *, int pid, int trace) |
1438 | |
1514 | |
1439 | Configures the watcher to wait for status changes of process C<pid> (or |
1515 | Configures the watcher to wait for status changes of process C<pid> (or |
1440 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1516 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1441 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1517 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1442 | the status word (use the macros from C<sys/wait.h> and see your systems |
1518 | the status word (use the macros from C<sys/wait.h> and see your systems |
1443 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1519 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1444 | process causing the status change. |
1520 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1521 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1522 | activate the watcher when the process is stopped or continued). |
1445 | |
1523 | |
1446 | =item int pid [read-only] |
1524 | =item int pid [read-only] |
1447 | |
1525 | |
1448 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1526 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1449 | |
1527 | |
… | |
… | |
1458 | |
1536 | |
1459 | =back |
1537 | =back |
1460 | |
1538 | |
1461 | =head3 Examples |
1539 | =head3 Examples |
1462 | |
1540 | |
1463 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1541 | Example: C<fork()> a new process and install a child handler to wait for |
|
|
1542 | its completion. |
|
|
1543 | |
|
|
1544 | ev_child cw; |
1464 | |
1545 | |
1465 | static void |
1546 | static void |
1466 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1547 | child_cb (EV_P_ struct ev_child *w, int revents) |
1467 | { |
1548 | { |
1468 | ev_unloop (loop, EVUNLOOP_ALL); |
1549 | ev_child_stop (EV_A_ w); |
|
|
1550 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1469 | } |
1551 | } |
1470 | |
1552 | |
1471 | struct ev_signal signal_watcher; |
1553 | pid_t pid = fork (); |
1472 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1554 | |
1473 | ev_signal_start (loop, &sigint_cb); |
1555 | if (pid < 0) |
|
|
1556 | // error |
|
|
1557 | else if (pid == 0) |
|
|
1558 | { |
|
|
1559 | // the forked child executes here |
|
|
1560 | exit (1); |
|
|
1561 | } |
|
|
1562 | else |
|
|
1563 | { |
|
|
1564 | ev_child_init (&cw, child_cb, pid, 0); |
|
|
1565 | ev_child_start (EV_DEFAULT_ &cw); |
|
|
1566 | } |
1474 | |
1567 | |
1475 | |
1568 | |
1476 | =head2 C<ev_stat> - did the file attributes just change? |
1569 | =head2 C<ev_stat> - did the file attributes just change? |
1477 | |
1570 | |
1478 | This watches a filesystem path for attribute changes. That is, it calls |
1571 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1507 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1600 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1508 | to fall back to regular polling again even with inotify, but changes are |
1601 | to fall back to regular polling again even with inotify, but changes are |
1509 | usually detected immediately, and if the file exists there will be no |
1602 | usually detected immediately, and if the file exists there will be no |
1510 | polling. |
1603 | polling. |
1511 | |
1604 | |
|
|
1605 | =head3 ABI Issues (Largefile Support) |
|
|
1606 | |
|
|
1607 | Libev by default (unless the user overrides this) uses the default |
|
|
1608 | compilation environment, which means that on systems with optionally |
|
|
1609 | disabled large file support, you get the 32 bit version of the stat |
|
|
1610 | structure. When using the library from programs that change the ABI to |
|
|
1611 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1612 | compile libev with the same flags to get binary compatibility. This is |
|
|
1613 | obviously the case with any flags that change the ABI, but the problem is |
|
|
1614 | most noticably with ev_stat and largefile support. |
|
|
1615 | |
1512 | =head3 Inotify |
1616 | =head3 Inotify |
1513 | |
1617 | |
1514 | When C<inotify (7)> support has been compiled into libev (generally only |
1618 | When C<inotify (7)> support has been compiled into libev (generally only |
1515 | available on Linux) and present at runtime, it will be used to speed up |
1619 | available on Linux) and present at runtime, it will be used to speed up |
1516 | change detection where possible. The inotify descriptor will be created lazily |
1620 | change detection where possible. The inotify descriptor will be created lazily |
… | |
… | |
1558 | |
1662 | |
1559 | The callback will be receive C<EV_STAT> when a change was detected, |
1663 | The callback will be receive C<EV_STAT> when a change was detected, |
1560 | relative to the attributes at the time the watcher was started (or the |
1664 | relative to the attributes at the time the watcher was started (or the |
1561 | last change was detected). |
1665 | last change was detected). |
1562 | |
1666 | |
1563 | =item ev_stat_stat (ev_stat *) |
1667 | =item ev_stat_stat (loop, ev_stat *) |
1564 | |
1668 | |
1565 | Updates the stat buffer immediately with new values. If you change the |
1669 | Updates the stat buffer immediately with new values. If you change the |
1566 | watched path in your callback, you could call this fucntion to avoid |
1670 | watched path in your callback, you could call this fucntion to avoid |
1567 | detecting this change (while introducing a race condition). Can also be |
1671 | detecting this change (while introducing a race condition). Can also be |
1568 | useful simply to find out the new values. |
1672 | useful simply to find out the new values. |
… | |
… | |
1685 | static void |
1789 | static void |
1686 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1790 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1687 | { |
1791 | { |
1688 | free (w); |
1792 | free (w); |
1689 | // now do something you wanted to do when the program has |
1793 | // now do something you wanted to do when the program has |
1690 | // no longer asnything immediate to do. |
1794 | // no longer anything immediate to do. |
1691 | } |
1795 | } |
1692 | |
1796 | |
1693 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1797 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1694 | ev_idle_init (idle_watcher, idle_cb); |
1798 | ev_idle_init (idle_watcher, idle_cb); |
1695 | ev_idle_start (loop, idle_cb); |
1799 | ev_idle_start (loop, idle_cb); |
… | |
… | |
2036 | believe me. |
2140 | believe me. |
2037 | |
2141 | |
2038 | =back |
2142 | =back |
2039 | |
2143 | |
2040 | |
2144 | |
|
|
2145 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2146 | |
|
|
2147 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2148 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2149 | loops - those are of course safe to use in different threads). |
|
|
2150 | |
|
|
2151 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2152 | control, for example because it belongs to another thread. This is what |
|
|
2153 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2154 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2155 | safe. |
|
|
2156 | |
|
|
2157 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2158 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2159 | (i.e. the number of callback invocations may be less than the number of |
|
|
2160 | C<ev_async_sent> calls). |
|
|
2161 | |
|
|
2162 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2163 | just the default loop. |
|
|
2164 | |
|
|
2165 | =head3 Queueing |
|
|
2166 | |
|
|
2167 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2168 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2169 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2170 | need elaborate support such as pthreads. |
|
|
2171 | |
|
|
2172 | That means that if you want to queue data, you have to provide your own |
|
|
2173 | queue. But at least I can tell you would implement locking around your |
|
|
2174 | queue: |
|
|
2175 | |
|
|
2176 | =over 4 |
|
|
2177 | |
|
|
2178 | =item queueing from a signal handler context |
|
|
2179 | |
|
|
2180 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2181 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2182 | some fictitiuous SIGUSR1 handler: |
|
|
2183 | |
|
|
2184 | static ev_async mysig; |
|
|
2185 | |
|
|
2186 | static void |
|
|
2187 | sigusr1_handler (void) |
|
|
2188 | { |
|
|
2189 | sometype data; |
|
|
2190 | |
|
|
2191 | // no locking etc. |
|
|
2192 | queue_put (data); |
|
|
2193 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2194 | } |
|
|
2195 | |
|
|
2196 | static void |
|
|
2197 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2198 | { |
|
|
2199 | sometype data; |
|
|
2200 | sigset_t block, prev; |
|
|
2201 | |
|
|
2202 | sigemptyset (&block); |
|
|
2203 | sigaddset (&block, SIGUSR1); |
|
|
2204 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2205 | |
|
|
2206 | while (queue_get (&data)) |
|
|
2207 | process (data); |
|
|
2208 | |
|
|
2209 | if (sigismember (&prev, SIGUSR1) |
|
|
2210 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2211 | } |
|
|
2212 | |
|
|
2213 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2214 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2215 | either...). |
|
|
2216 | |
|
|
2217 | =item queueing from a thread context |
|
|
2218 | |
|
|
2219 | The strategy for threads is different, as you cannot (easily) block |
|
|
2220 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2221 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2222 | |
|
|
2223 | static ev_async mysig; |
|
|
2224 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2225 | |
|
|
2226 | static void |
|
|
2227 | otherthread (void) |
|
|
2228 | { |
|
|
2229 | // only need to lock the actual queueing operation |
|
|
2230 | pthread_mutex_lock (&mymutex); |
|
|
2231 | queue_put (data); |
|
|
2232 | pthread_mutex_unlock (&mymutex); |
|
|
2233 | |
|
|
2234 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2235 | } |
|
|
2236 | |
|
|
2237 | static void |
|
|
2238 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2239 | { |
|
|
2240 | pthread_mutex_lock (&mymutex); |
|
|
2241 | |
|
|
2242 | while (queue_get (&data)) |
|
|
2243 | process (data); |
|
|
2244 | |
|
|
2245 | pthread_mutex_unlock (&mymutex); |
|
|
2246 | } |
|
|
2247 | |
|
|
2248 | =back |
|
|
2249 | |
|
|
2250 | |
|
|
2251 | =head3 Watcher-Specific Functions and Data Members |
|
|
2252 | |
|
|
2253 | =over 4 |
|
|
2254 | |
|
|
2255 | =item ev_async_init (ev_async *, callback) |
|
|
2256 | |
|
|
2257 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2258 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2259 | believe me. |
|
|
2260 | |
|
|
2261 | =item ev_async_send (loop, ev_async *) |
|
|
2262 | |
|
|
2263 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2264 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2265 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2266 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2267 | section below on what exactly this means). |
|
|
2268 | |
|
|
2269 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2270 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2271 | calls to C<ev_async_send>. |
|
|
2272 | |
|
|
2273 | =back |
|
|
2274 | |
|
|
2275 | |
2041 | =head1 OTHER FUNCTIONS |
2276 | =head1 OTHER FUNCTIONS |
2042 | |
2277 | |
2043 | There are some other functions of possible interest. Described. Here. Now. |
2278 | There are some other functions of possible interest. Described. Here. Now. |
2044 | |
2279 | |
2045 | =over 4 |
2280 | =over 4 |
… | |
… | |
2272 | Example: Define a class with an IO and idle watcher, start one of them in |
2507 | Example: Define a class with an IO and idle watcher, start one of them in |
2273 | the constructor. |
2508 | the constructor. |
2274 | |
2509 | |
2275 | class myclass |
2510 | class myclass |
2276 | { |
2511 | { |
2277 | ev_io io; void io_cb (ev::io &w, int revents); |
2512 | ev::io io; void io_cb (ev::io &w, int revents); |
2278 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2513 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2279 | |
2514 | |
2280 | myclass (); |
2515 | myclass (int fd) |
2281 | } |
|
|
2282 | |
|
|
2283 | myclass::myclass (int fd) |
|
|
2284 | { |
2516 | { |
2285 | io .set <myclass, &myclass::io_cb > (this); |
2517 | io .set <myclass, &myclass::io_cb > (this); |
2286 | idle.set <myclass, &myclass::idle_cb> (this); |
2518 | idle.set <myclass, &myclass::idle_cb> (this); |
2287 | |
2519 | |
2288 | io.start (fd, ev::READ); |
2520 | io.start (fd, ev::READ); |
|
|
2521 | } |
2289 | } |
2522 | }; |
|
|
2523 | |
|
|
2524 | |
|
|
2525 | =head1 OTHER LANGUAGE BINDINGS |
|
|
2526 | |
|
|
2527 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2528 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2529 | any interesting language binding in addition to the ones listed here, drop |
|
|
2530 | me a note. |
|
|
2531 | |
|
|
2532 | =over 4 |
|
|
2533 | |
|
|
2534 | =item Perl |
|
|
2535 | |
|
|
2536 | The EV module implements the full libev API and is actually used to test |
|
|
2537 | libev. EV is developed together with libev. Apart from the EV core module, |
|
|
2538 | there are additional modules that implement libev-compatible interfaces |
|
|
2539 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
|
|
2540 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
|
|
2541 | |
|
|
2542 | It can be found and installed via CPAN, its homepage is found at |
|
|
2543 | L<http://software.schmorp.de/pkg/EV>. |
|
|
2544 | |
|
|
2545 | =item Ruby |
|
|
2546 | |
|
|
2547 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2548 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
|
|
2549 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2550 | L<http://rev.rubyforge.org/>. |
|
|
2551 | |
|
|
2552 | =item D |
|
|
2553 | |
|
|
2554 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
|
|
2555 | be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2556 | |
|
|
2557 | =back |
2290 | |
2558 | |
2291 | |
2559 | |
2292 | =head1 MACRO MAGIC |
2560 | =head1 MACRO MAGIC |
2293 | |
2561 | |
2294 | Libev can be compiled with a variety of options, the most fundamantal |
2562 | Libev can be compiled with a variety of options, the most fundamantal |
… | |
… | |
2550 | |
2818 | |
2551 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2819 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2552 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2820 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2553 | be detected at runtime. |
2821 | be detected at runtime. |
2554 | |
2822 | |
|
|
2823 | =item EV_ATOMIC_T |
|
|
2824 | |
|
|
2825 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2826 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2827 | type is easily found in the C language, so you can provide your own type |
|
|
2828 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2829 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2830 | |
|
|
2831 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2832 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2833 | |
2555 | =item EV_H |
2834 | =item EV_H |
2556 | |
2835 | |
2557 | The name of the F<ev.h> header file used to include it. The default if |
2836 | The name of the F<ev.h> header file used to include it. The default if |
2558 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2837 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2559 | virtually rename the F<ev.h> header file in case of conflicts. |
2838 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2560 | |
2839 | |
2561 | =item EV_CONFIG_H |
2840 | =item EV_CONFIG_H |
2562 | |
2841 | |
2563 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2842 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2564 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2843 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2565 | C<EV_H>, above. |
2844 | C<EV_H>, above. |
2566 | |
2845 | |
2567 | =item EV_EVENT_H |
2846 | =item EV_EVENT_H |
2568 | |
2847 | |
2569 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2848 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2570 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2849 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2571 | |
2850 | |
2572 | =item EV_PROTOTYPES |
2851 | =item EV_PROTOTYPES |
2573 | |
2852 | |
2574 | If defined to be C<0>, then F<ev.h> will not define any function |
2853 | If defined to be C<0>, then F<ev.h> will not define any function |
2575 | prototypes, but still define all the structs and other symbols. This is |
2854 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2624 | defined to be C<0>, then they are not. |
2903 | defined to be C<0>, then they are not. |
2625 | |
2904 | |
2626 | =item EV_FORK_ENABLE |
2905 | =item EV_FORK_ENABLE |
2627 | |
2906 | |
2628 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2907 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2908 | defined to be C<0>, then they are not. |
|
|
2909 | |
|
|
2910 | =item EV_ASYNC_ENABLE |
|
|
2911 | |
|
|
2912 | If undefined or defined to be C<1>, then async watchers are supported. If |
2629 | defined to be C<0>, then they are not. |
2913 | defined to be C<0>, then they are not. |
2630 | |
2914 | |
2631 | =item EV_MINIMAL |
2915 | =item EV_MINIMAL |
2632 | |
2916 | |
2633 | If you need to shave off some kilobytes of code at the expense of some |
2917 | If you need to shave off some kilobytes of code at the expense of some |
… | |
… | |
2754 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
3038 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2755 | |
3039 | |
2756 | That means that changing a timer costs less than removing/adding them |
3040 | That means that changing a timer costs less than removing/adding them |
2757 | as only the relative motion in the event queue has to be paid for. |
3041 | as only the relative motion in the event queue has to be paid for. |
2758 | |
3042 | |
2759 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
3043 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2760 | |
3044 | |
2761 | These just add the watcher into an array or at the head of a list. |
3045 | These just add the watcher into an array or at the head of a list. |
2762 | |
3046 | |
2763 | =item Stopping check/prepare/idle watchers: O(1) |
3047 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2764 | |
3048 | |
2765 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
3049 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2766 | |
3050 | |
2767 | These watchers are stored in lists then need to be walked to find the |
3051 | These watchers are stored in lists then need to be walked to find the |
2768 | correct watcher to remove. The lists are usually short (you don't usually |
3052 | correct watcher to remove. The lists are usually short (you don't usually |
… | |
… | |
2784 | =item Priority handling: O(number_of_priorities) |
3068 | =item Priority handling: O(number_of_priorities) |
2785 | |
3069 | |
2786 | Priorities are implemented by allocating some space for each |
3070 | Priorities are implemented by allocating some space for each |
2787 | priority. When doing priority-based operations, libev usually has to |
3071 | priority. When doing priority-based operations, libev usually has to |
2788 | linearly search all the priorities, but starting/stopping and activating |
3072 | linearly search all the priorities, but starting/stopping and activating |
2789 | watchers becomes O(1) w.r.t. prioritiy handling. |
3073 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3074 | |
|
|
3075 | =item Sending an ev_async: O(1) |
|
|
3076 | |
|
|
3077 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3078 | |
|
|
3079 | =item Processing signals: O(max_signal_number) |
|
|
3080 | |
|
|
3081 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3082 | calls in the current loop iteration. Checking for async and signal events |
|
|
3083 | involves iterating over all running async watchers or all signal numbers. |
2790 | |
3084 | |
2791 | =back |
3085 | =back |
2792 | |
3086 | |
2793 | |
3087 | |
2794 | =head1 Win32 platform limitations and workarounds |
3088 | =head1 Win32 platform limitations and workarounds |