… | |
… | |
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 |
… | |
… | |
297 | enabling this flag. |
312 | enabling this flag. |
298 | |
313 | |
299 | 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, |
300 | 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 |
301 | 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 |
302 | 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 |
303 | 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 |
304 | C<pthread_atfork> which is even faster). |
319 | C<pthread_atfork> which is even faster). |
305 | |
320 | |
306 | 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 |
307 | 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 |
308 | flag. |
323 | flag. |
… | |
… | |
1070 | To support fork in your programs, you either have to call |
1085 | To support fork in your programs, you either have to call |
1071 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1086 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1072 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1087 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1073 | C<EVBACKEND_POLL>. |
1088 | C<EVBACKEND_POLL>. |
1074 | |
1089 | |
|
|
1090 | =head3 The special problem of SIGPIPE |
|
|
1091 | |
|
|
1092 | While not really specific to libev, it is easy to forget about SIGPIPE: |
|
|
1093 | when reading from a pipe whose other end has been closed, your program |
|
|
1094 | gets send a SIGPIPE, which, by default, aborts your program. For most |
|
|
1095 | programs this is sensible behaviour, for daemons, this is usually |
|
|
1096 | undesirable. |
|
|
1097 | |
|
|
1098 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1099 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
|
|
1100 | somewhere, as that would have given you a big clue). |
|
|
1101 | |
1075 | |
1102 | |
1076 | =head3 Watcher-Specific Functions |
1103 | =head3 Watcher-Specific Functions |
1077 | |
1104 | |
1078 | =over 4 |
1105 | =over 4 |
1079 | |
1106 | |
… | |
… | |
1418 | first watcher gets started will libev actually register a signal watcher |
1445 | first watcher gets started will libev actually register a signal watcher |
1419 | with the kernel (thus it coexists with your own signal handlers as long |
1446 | with the kernel (thus it coexists with your own signal handlers as long |
1420 | as you don't register any with libev). Similarly, when the last signal |
1447 | as you don't register any with libev). Similarly, when the last signal |
1421 | watcher for a signal is stopped libev will reset the signal handler to |
1448 | watcher for a signal is stopped libev will reset the signal handler to |
1422 | SIG_DFL (regardless of what it was set to before). |
1449 | SIG_DFL (regardless of what it was set to before). |
|
|
1450 | |
|
|
1451 | If possible and supported, libev will install its handlers with |
|
|
1452 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
|
|
1453 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1454 | signals you can block all signals in an C<ev_check> watcher and unblock |
|
|
1455 | them in an C<ev_prepare> watcher. |
1423 | |
1456 | |
1424 | =head3 Watcher-Specific Functions and Data Members |
1457 | =head3 Watcher-Specific Functions and Data Members |
1425 | |
1458 | |
1426 | =over 4 |
1459 | =over 4 |
1427 | |
1460 | |
… | |
… | |
1578 | reader). Inotify will be used to give hints only and should not change the |
1611 | reader). Inotify will be used to give hints only and should not change the |
1579 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1612 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1580 | to fall back to regular polling again even with inotify, but changes are |
1613 | to fall back to regular polling again even with inotify, but changes are |
1581 | usually detected immediately, and if the file exists there will be no |
1614 | usually detected immediately, and if the file exists there will be no |
1582 | polling. |
1615 | polling. |
|
|
1616 | |
|
|
1617 | =head3 ABI Issues (Largefile Support) |
|
|
1618 | |
|
|
1619 | Libev by default (unless the user overrides this) uses the default |
|
|
1620 | compilation environment, which means that on systems with optionally |
|
|
1621 | disabled large file support, you get the 32 bit version of the stat |
|
|
1622 | structure. When using the library from programs that change the ABI to |
|
|
1623 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1624 | compile libev with the same flags to get binary compatibility. This is |
|
|
1625 | obviously the case with any flags that change the ABI, but the problem is |
|
|
1626 | most noticably with ev_stat and largefile support. |
1583 | |
1627 | |
1584 | =head3 Inotify |
1628 | =head3 Inotify |
1585 | |
1629 | |
1586 | When C<inotify (7)> support has been compiled into libev (generally only |
1630 | When C<inotify (7)> support has been compiled into libev (generally only |
1587 | available on Linux) and present at runtime, it will be used to speed up |
1631 | available on Linux) and present at runtime, it will be used to speed up |
… | |
… | |
2488 | io.start (fd, ev::READ); |
2532 | io.start (fd, ev::READ); |
2489 | } |
2533 | } |
2490 | }; |
2534 | }; |
2491 | |
2535 | |
2492 | |
2536 | |
|
|
2537 | =head1 OTHER LANGUAGE BINDINGS |
|
|
2538 | |
|
|
2539 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2540 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2541 | any interesting language binding in addition to the ones listed here, drop |
|
|
2542 | me a note. |
|
|
2543 | |
|
|
2544 | =over 4 |
|
|
2545 | |
|
|
2546 | =item Perl |
|
|
2547 | |
|
|
2548 | The EV module implements the full libev API and is actually used to test |
|
|
2549 | libev. EV is developed together with libev. Apart from the EV core module, |
|
|
2550 | there are additional modules that implement libev-compatible interfaces |
|
|
2551 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
|
|
2552 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
|
|
2553 | |
|
|
2554 | It can be found and installed via CPAN, its homepage is found at |
|
|
2555 | L<http://software.schmorp.de/pkg/EV>. |
|
|
2556 | |
|
|
2557 | =item Ruby |
|
|
2558 | |
|
|
2559 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2560 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
|
|
2561 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2562 | L<http://rev.rubyforge.org/>. |
|
|
2563 | |
|
|
2564 | =item D |
|
|
2565 | |
|
|
2566 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
|
|
2567 | be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2568 | |
|
|
2569 | =back |
|
|
2570 | |
|
|
2571 | |
2493 | =head1 MACRO MAGIC |
2572 | =head1 MACRO MAGIC |
2494 | |
2573 | |
2495 | Libev can be compiled with a variety of options, the most fundamantal |
2574 | Libev can be compiled with a variety of options, the most fundamantal |
2496 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2575 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2497 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2576 | functions and callbacks have an initial C<struct ev_loop *> argument. |