… | |
… | |
17 | ev_timer timeout_watcher; |
17 | ev_timer timeout_watcher; |
18 | |
18 | |
19 | // all watcher callbacks have a similar signature |
19 | // all watcher callbacks have a similar signature |
20 | // this callback is called when data is readable on stdin |
20 | // this callback is called when data is readable on stdin |
21 | static void |
21 | static void |
22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
22 | stdin_cb (EV_P_ ev_io *w, int revents) |
23 | { |
23 | { |
24 | puts ("stdin ready"); |
24 | puts ("stdin ready"); |
25 | // for one-shot events, one must manually stop the watcher |
25 | // for one-shot events, one must manually stop the watcher |
26 | // with its corresponding stop function. |
26 | // with its corresponding stop function. |
27 | ev_io_stop (EV_A_ w); |
27 | ev_io_stop (EV_A_ w); |
… | |
… | |
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
31 | } |
31 | } |
32 | |
32 | |
33 | // another callback, this time for a time-out |
33 | // another callback, this time for a time-out |
34 | static void |
34 | static void |
35 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
35 | timeout_cb (EV_P_ ev_timer *w, int revents) |
36 | { |
36 | { |
37 | puts ("timeout"); |
37 | puts ("timeout"); |
38 | // this causes the innermost ev_loop to stop iterating |
38 | // this causes the innermost ev_loop to stop iterating |
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
40 | } |
40 | } |
41 | |
41 | |
42 | int |
42 | int |
43 | main (void) |
43 | main (void) |
44 | { |
44 | { |
45 | // use the default event loop unless you have special needs |
45 | // use the default event loop unless you have special needs |
46 | struct ev_loop *loop = ev_default_loop (0); |
46 | ev_loop *loop = ev_default_loop (0); |
47 | |
47 | |
48 | // 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 |
49 | // this one will watch for stdin to become readable |
50 | 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); |
51 | ev_io_start (loop, &stdin_watcher); |
51 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
103 | Libev is very configurable. In this manual the default (and most common) |
103 | Libev is very configurable. In this manual the default (and most common) |
104 | configuration will be described, which supports multiple event loops. For |
104 | configuration will be described, which supports multiple event loops. For |
105 | more info about various configuration options please have a look at |
105 | more info about various configuration options please have a look at |
106 | B<EMBED> section in this manual. If libev was configured without support |
106 | B<EMBED> section in this manual. If libev was configured without support |
107 | for multiple event loops, then all functions taking an initial argument of |
107 | for multiple event loops, then all functions taking an initial argument of |
108 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
108 | name C<loop> (which is always of type C<ev_loop *>) will not have |
109 | this argument. |
109 | this argument. |
110 | |
110 | |
111 | =head2 TIME REPRESENTATION |
111 | =head2 TIME REPRESENTATION |
112 | |
112 | |
113 | Libev represents time as a single floating point number, representing the |
113 | Libev represents time as a single floating point number, representing the |
… | |
… | |
276 | |
276 | |
277 | =back |
277 | =back |
278 | |
278 | |
279 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
279 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
280 | |
280 | |
281 | An event loop is described by a C<struct ev_loop *>. The library knows two |
281 | An event loop is described by a C<ev_loop *>. The library knows two |
282 | types of such loops, the I<default> loop, which supports signals and child |
282 | types of such loops, the I<default> loop, which supports signals and child |
283 | events, and dynamically created loops which do not. |
283 | events, and dynamically created loops which do not. |
284 | |
284 | |
285 | =over 4 |
285 | =over 4 |
286 | |
286 | |
… | |
… | |
685 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
685 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
686 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
686 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
687 | |
687 | |
688 | This "unloop state" will be cleared when entering C<ev_loop> again. |
688 | This "unloop state" will be cleared when entering C<ev_loop> again. |
689 | |
689 | |
|
|
690 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
|
|
691 | |
690 | =item ev_ref (loop) |
692 | =item ev_ref (loop) |
691 | |
693 | |
692 | =item ev_unref (loop) |
694 | =item ev_unref (loop) |
693 | |
695 | |
694 | Ref/unref can be used to add or remove a reference count on the event |
696 | Ref/unref can be used to add or remove a reference count on the event |
… | |
… | |
708 | respectively). |
710 | respectively). |
709 | |
711 | |
710 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
712 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
711 | running when nothing else is active. |
713 | running when nothing else is active. |
712 | |
714 | |
713 | struct ev_signal exitsig; |
715 | ev_signal exitsig; |
714 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
716 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
715 | ev_signal_start (loop, &exitsig); |
717 | ev_signal_start (loop, &exitsig); |
716 | evf_unref (loop); |
718 | evf_unref (loop); |
717 | |
719 | |
718 | Example: For some weird reason, unregister the above signal handler again. |
720 | Example: For some weird reason, unregister the above signal handler again. |
… | |
… | |
784 | |
786 | |
785 | A watcher is a structure that you create and register to record your |
787 | A watcher is a structure that you create and register to record your |
786 | interest in some event. For instance, if you want to wait for STDIN to |
788 | interest in some event. For instance, if you want to wait for STDIN to |
787 | become readable, you would create an C<ev_io> watcher for that: |
789 | become readable, you would create an C<ev_io> watcher for that: |
788 | |
790 | |
789 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
791 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
790 | { |
792 | { |
791 | ev_io_stop (w); |
793 | ev_io_stop (w); |
792 | ev_unloop (loop, EVUNLOOP_ALL); |
794 | ev_unloop (loop, EVUNLOOP_ALL); |
793 | } |
795 | } |
794 | |
796 | |
795 | struct ev_loop *loop = ev_default_loop (0); |
797 | struct ev_loop *loop = ev_default_loop (0); |
796 | struct ev_io stdin_watcher; |
798 | ev_io stdin_watcher; |
797 | ev_init (&stdin_watcher, my_cb); |
799 | ev_init (&stdin_watcher, my_cb); |
798 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
800 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
799 | ev_io_start (loop, &stdin_watcher); |
801 | ev_io_start (loop, &stdin_watcher); |
800 | ev_loop (loop, 0); |
802 | ev_loop (loop, 0); |
801 | |
803 | |
… | |
… | |
892 | =item C<EV_ERROR> |
894 | =item C<EV_ERROR> |
893 | |
895 | |
894 | An unspecified error has occurred, the watcher has been stopped. This might |
896 | An unspecified error has occurred, the watcher has been stopped. This might |
895 | happen because the watcher could not be properly started because libev |
897 | happen because the watcher could not be properly started because libev |
896 | ran out of memory, a file descriptor was found to be closed or any other |
898 | ran out of memory, a file descriptor was found to be closed or any other |
|
|
899 | problem. Libev considers these application bugs. |
|
|
900 | |
897 | problem. You best act on it by reporting the problem and somehow coping |
901 | You best act on it by reporting the problem and somehow coping with the |
898 | with the watcher being stopped. |
902 | watcher being stopped. Note that well-written programs should not receive |
|
|
903 | an error ever, so when your watcher receives it, this usually indicates a |
|
|
904 | bug in your program. |
899 | |
905 | |
900 | Libev will usually signal a few "dummy" events together with an error, for |
906 | Libev will usually signal a few "dummy" events together with an error, for |
901 | example it might indicate that a fd is readable or writable, and if your |
907 | example it might indicate that a fd is readable or writable, and if your |
902 | callbacks is well-written it can just attempt the operation and cope with |
908 | callbacks is well-written it can just attempt the operation and cope with |
903 | the error from read() or write(). This will not work in multi-threaded |
909 | the error from read() or write(). This will not work in multi-threaded |
… | |
… | |
923 | which rolls both calls into one. |
929 | which rolls both calls into one. |
924 | |
930 | |
925 | You can reinitialise a watcher at any time as long as it has been stopped |
931 | You can reinitialise a watcher at any time as long as it has been stopped |
926 | (or never started) and there are no pending events outstanding. |
932 | (or never started) and there are no pending events outstanding. |
927 | |
933 | |
928 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
934 | The callback is always of type C<void (*)(struct ev_loop *loop, ev_TYPE *watcher, |
929 | int revents)>. |
935 | int revents)>. |
930 | |
936 | |
931 | Example: Initialise an C<ev_io> watcher in two steps. |
937 | Example: Initialise an C<ev_io> watcher in two steps. |
932 | |
938 | |
933 | ev_io w; |
939 | ev_io w; |
… | |
… | |
967 | |
973 | |
968 | ev_io_start (EV_DEFAULT_UC, &w); |
974 | ev_io_start (EV_DEFAULT_UC, &w); |
969 | |
975 | |
970 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
976 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
971 | |
977 | |
972 | Stops the given watcher again (if active) and clears the pending |
978 | Stops the given watcher if active, and clears the pending status (whether |
|
|
979 | the watcher was active or not). |
|
|
980 | |
973 | status. It is possible that stopped watchers are pending (for example, |
981 | It is possible that stopped watchers are pending - for example, |
974 | non-repeating timers are being stopped when they become pending), but |
982 | non-repeating timers are being stopped when they become pending - but |
975 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
983 | calling C<ev_TYPE_stop> ensures that the watcher is neither active nor |
976 | you want to free or reuse the memory used by the watcher it is therefore a |
984 | pending. If you want to free or reuse the memory used by the watcher it is |
977 | good idea to always call its C<ev_TYPE_stop> function. |
985 | therefore a good idea to always call its C<ev_TYPE_stop> function. |
978 | |
986 | |
979 | =item bool ev_is_active (ev_TYPE *watcher) |
987 | =item bool ev_is_active (ev_TYPE *watcher) |
980 | |
988 | |
981 | Returns a true value iff the watcher is active (i.e. it has been started |
989 | Returns a true value iff the watcher is active (i.e. it has been started |
982 | and not yet been stopped). As long as a watcher is active you must not modify |
990 | and not yet been stopped). As long as a watcher is active you must not modify |
… | |
… | |
1056 | member, you can also "subclass" the watcher type and provide your own |
1064 | member, you can also "subclass" the watcher type and provide your own |
1057 | data: |
1065 | data: |
1058 | |
1066 | |
1059 | struct my_io |
1067 | struct my_io |
1060 | { |
1068 | { |
1061 | struct ev_io io; |
1069 | ev_io io; |
1062 | int otherfd; |
1070 | int otherfd; |
1063 | void *somedata; |
1071 | void *somedata; |
1064 | struct whatever *mostinteresting; |
1072 | struct whatever *mostinteresting; |
1065 | }; |
1073 | }; |
1066 | |
1074 | |
… | |
… | |
1069 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
1077 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
1070 | |
1078 | |
1071 | And since your callback will be called with a pointer to the watcher, you |
1079 | And since your callback will be called with a pointer to the watcher, you |
1072 | can cast it back to your own type: |
1080 | can cast it back to your own type: |
1073 | |
1081 | |
1074 | static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1082 | static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
1075 | { |
1083 | { |
1076 | struct my_io *w = (struct my_io *)w_; |
1084 | struct my_io *w = (struct my_io *)w_; |
1077 | ... |
1085 | ... |
1078 | } |
1086 | } |
1079 | |
1087 | |
… | |
… | |
1097 | programmers): |
1105 | programmers): |
1098 | |
1106 | |
1099 | #include <stddef.h> |
1107 | #include <stddef.h> |
1100 | |
1108 | |
1101 | static void |
1109 | static void |
1102 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
1110 | t1_cb (EV_P_ ev_timer *w, int revents) |
1103 | { |
1111 | { |
1104 | struct my_biggy big = (struct my_biggy * |
1112 | struct my_biggy big = (struct my_biggy * |
1105 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1113 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1106 | } |
1114 | } |
1107 | |
1115 | |
1108 | static void |
1116 | static void |
1109 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
1117 | t2_cb (EV_P_ ev_timer *w, int revents) |
1110 | { |
1118 | { |
1111 | struct my_biggy big = (struct my_biggy * |
1119 | struct my_biggy big = (struct my_biggy * |
1112 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1120 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1113 | } |
1121 | } |
1114 | |
1122 | |
… | |
… | |
1249 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1257 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1250 | readable, but only once. Since it is likely line-buffered, you could |
1258 | readable, but only once. Since it is likely line-buffered, you could |
1251 | attempt to read a whole line in the callback. |
1259 | attempt to read a whole line in the callback. |
1252 | |
1260 | |
1253 | static void |
1261 | static void |
1254 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1262 | stdin_readable_cb (struct ev_loop *loop, ev_io *w, int revents) |
1255 | { |
1263 | { |
1256 | ev_io_stop (loop, w); |
1264 | ev_io_stop (loop, w); |
1257 | .. read from stdin here (or from w->fd) and handle any I/O errors |
1265 | .. read from stdin here (or from w->fd) and handle any I/O errors |
1258 | } |
1266 | } |
1259 | |
1267 | |
1260 | ... |
1268 | ... |
1261 | struct ev_loop *loop = ev_default_init (0); |
1269 | struct ev_loop *loop = ev_default_init (0); |
1262 | struct ev_io stdin_readable; |
1270 | ev_io stdin_readable; |
1263 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1271 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1264 | ev_io_start (loop, &stdin_readable); |
1272 | ev_io_start (loop, &stdin_readable); |
1265 | ev_loop (loop, 0); |
1273 | ev_loop (loop, 0); |
1266 | |
1274 | |
1267 | |
1275 | |
… | |
… | |
1278 | |
1286 | |
1279 | The callback is guaranteed to be invoked only I<after> its timeout has |
1287 | The callback is guaranteed to be invoked only I<after> its timeout has |
1280 | passed, but if multiple timers become ready during the same loop iteration |
1288 | passed, but if multiple timers become ready during the same loop iteration |
1281 | then order of execution is undefined. |
1289 | then order of execution is undefined. |
1282 | |
1290 | |
|
|
1291 | =head3 Be smart about timeouts |
|
|
1292 | |
|
|
1293 | Many real-world problems invole some kind of time-out, usually for error |
|
|
1294 | recovery. A typical example is an HTTP request - if the other side hangs, |
|
|
1295 | you want to raise some error after a while. |
|
|
1296 | |
|
|
1297 | Here are some ways on how to handle this problem, from simple and |
|
|
1298 | inefficient to very efficient. |
|
|
1299 | |
|
|
1300 | In the following examples a 60 second activity timeout is assumed - a |
|
|
1301 | timeout that gets reset to 60 seconds each time some data ("a lifesign") |
|
|
1302 | was received. |
|
|
1303 | |
|
|
1304 | =over 4 |
|
|
1305 | |
|
|
1306 | =item 1. Use a timer and stop, reinitialise, start it on activity. |
|
|
1307 | |
|
|
1308 | This is the most obvious, but not the most simple way: In the beginning, |
|
|
1309 | start the watcher: |
|
|
1310 | |
|
|
1311 | ev_timer_init (timer, callback, 60., 0.); |
|
|
1312 | ev_timer_start (loop, timer); |
|
|
1313 | |
|
|
1314 | Then, each time there is some activity, C<ev_timer_stop> the timer, |
|
|
1315 | initialise it again, and start it: |
|
|
1316 | |
|
|
1317 | ev_timer_stop (loop, timer); |
|
|
1318 | ev_timer_set (timer, 60., 0.); |
|
|
1319 | ev_timer_start (loop, timer); |
|
|
1320 | |
|
|
1321 | This is relatively simple to implement, but means that each time there |
|
|
1322 | is some activity, libev will first have to remove the timer from it's |
|
|
1323 | internal data strcuture and then add it again. |
|
|
1324 | |
|
|
1325 | =item 2. Use a timer and re-start it with C<ev_timer_again> inactivity. |
|
|
1326 | |
|
|
1327 | This is the easiest way, and involves using C<ev_timer_again> instead of |
|
|
1328 | C<ev_timer_start>. |
|
|
1329 | |
|
|
1330 | For this, configure an C<ev_timer> with a C<repeat> value of C<60> and |
|
|
1331 | then call C<ev_timer_again> at start and each time you successfully read |
|
|
1332 | or write some data. If you go into an idle state where you do not expect |
|
|
1333 | data to travel on the socket, you can C<ev_timer_stop> the timer, and |
|
|
1334 | C<ev_timer_again> will automatically restart it if need be. |
|
|
1335 | |
|
|
1336 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1337 | altogether and only ever use the C<repeat> value and C<ev_timer_again>. |
|
|
1338 | |
|
|
1339 | At start: |
|
|
1340 | |
|
|
1341 | ev_timer_init (timer, callback, 0., 60.); |
|
|
1342 | ev_timer_again (loop, timer); |
|
|
1343 | |
|
|
1344 | Each time you receive some data: |
|
|
1345 | |
|
|
1346 | ev_timer_again (loop, timer); |
|
|
1347 | |
|
|
1348 | It is even possible to change the time-out on the fly: |
|
|
1349 | |
|
|
1350 | timer->repeat = 30.; |
|
|
1351 | ev_timer_again (loop, timer); |
|
|
1352 | |
|
|
1353 | This is slightly more efficient then stopping/starting the timer each time |
|
|
1354 | you want to modify its timeout value, as libev does not have to completely |
|
|
1355 | remove and re-insert the timer from/into it's internal data structure. |
|
|
1356 | |
|
|
1357 | =item 3. Let the timer time out, but then re-arm it as required. |
|
|
1358 | |
|
|
1359 | This method is more tricky, but usually most efficient: Most timeouts are |
|
|
1360 | relatively long compared to the loop iteration time - in our example, |
|
|
1361 | within 60 seconds, there are usually many I/O events with associated |
|
|
1362 | activity resets. |
|
|
1363 | |
|
|
1364 | In this case, it would be more efficient to leave the C<ev_timer> alone, |
|
|
1365 | but remember the time of last activity, and check for a real timeout only |
|
|
1366 | within the callback: |
|
|
1367 | |
|
|
1368 | ev_tstamp last_activity; // time of last activity |
|
|
1369 | |
|
|
1370 | static void |
|
|
1371 | callback (EV_P_ ev_timer *w, int revents) |
|
|
1372 | { |
|
|
1373 | ev_tstamp now = ev_now (EV_A); |
|
|
1374 | ev_tstamp timeout = last_activity + 60.; |
|
|
1375 | |
|
|
1376 | // if last_activity is older than now - timeout, we did time out |
|
|
1377 | if (timeout < now) |
|
|
1378 | { |
|
|
1379 | // timeout occured, take action |
|
|
1380 | } |
|
|
1381 | else |
|
|
1382 | { |
|
|
1383 | // callback was invoked, but there was some activity, re-arm |
|
|
1384 | // to fire in last_activity + 60. |
|
|
1385 | w->again = timeout - now; |
|
|
1386 | ev_timer_again (EV_A_ w); |
|
|
1387 | } |
|
|
1388 | } |
|
|
1389 | |
|
|
1390 | To summarise the callback: first calculate the real time-out (defined as |
|
|
1391 | "60 seconds after the last activity"), then check if that time has been |
|
|
1392 | reached, which means there was a real timeout. Otherwise the callback was |
|
|
1393 | invoked too early (timeout is in the future), so re-schedule the timer to |
|
|
1394 | fire at that future time. |
|
|
1395 | |
|
|
1396 | Note how C<ev_timer_again> is used, taking advantage of the |
|
|
1397 | C<ev_timer_again> optimisation when the timer is already running. |
|
|
1398 | |
|
|
1399 | This scheme causes more callback invocations (about one every 60 seconds), |
|
|
1400 | but virtually no calls to libev to change the timeout. |
|
|
1401 | |
|
|
1402 | To start the timer, simply intiialise the watcher and C<last_activity>, |
|
|
1403 | then call the callback: |
|
|
1404 | |
|
|
1405 | ev_timer_init (timer, callback); |
|
|
1406 | last_activity = ev_now (loop); |
|
|
1407 | callback (loop, timer, EV_TIMEOUT); |
|
|
1408 | |
|
|
1409 | And when there is some activity, simply remember the time in |
|
|
1410 | C<last_activity>: |
|
|
1411 | |
|
|
1412 | last_actiivty = ev_now (loop); |
|
|
1413 | |
|
|
1414 | This technique is slightly more complex, but in most cases where the |
|
|
1415 | time-out is unlikely to be triggered, much more efficient. |
|
|
1416 | |
|
|
1417 | =back |
|
|
1418 | |
1283 | =head3 The special problem of time updates |
1419 | =head3 The special problem of time updates |
1284 | |
1420 | |
1285 | Establishing the current time is a costly operation (it usually takes at |
1421 | Establishing the current time is a costly operation (it usually takes at |
1286 | least two system calls): EV therefore updates its idea of the current |
1422 | least two system calls): EV therefore updates its idea of the current |
1287 | time only before and after C<ev_loop> collects new events, which causes a |
1423 | time only before and after C<ev_loop> collects new events, which causes a |
… | |
… | |
1330 | If the timer is started but non-repeating, stop it (as if it timed out). |
1466 | If the timer is started but non-repeating, stop it (as if it timed out). |
1331 | |
1467 | |
1332 | If the timer is repeating, either start it if necessary (with the |
1468 | If the timer is repeating, either start it if necessary (with the |
1333 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1469 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1334 | |
1470 | |
1335 | This sounds a bit complicated, but here is a useful and typical |
1471 | This sounds a bit complicated, see "Be smart about timeouts", above, for a |
1336 | example: Imagine you have a TCP connection and you want a so-called idle |
1472 | usage example. |
1337 | timeout, that is, you want to be called when there have been, say, 60 |
|
|
1338 | seconds of inactivity on the socket. The easiest way to do this is to |
|
|
1339 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
|
|
1340 | C<ev_timer_again> each time you successfully read or write some data. If |
|
|
1341 | you go into an idle state where you do not expect data to travel on the |
|
|
1342 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
1343 | automatically restart it if need be. |
|
|
1344 | |
|
|
1345 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1346 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1347 | |
|
|
1348 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1349 | ev_timer_again (loop, timer); |
|
|
1350 | ... |
|
|
1351 | timer->again = 17.; |
|
|
1352 | ev_timer_again (loop, timer); |
|
|
1353 | ... |
|
|
1354 | timer->again = 10.; |
|
|
1355 | ev_timer_again (loop, timer); |
|
|
1356 | |
|
|
1357 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1358 | you want to modify its timeout value. |
|
|
1359 | |
|
|
1360 | Note, however, that it is often even more efficient to remember the |
|
|
1361 | time of the last activity and let the timer time-out naturally. In the |
|
|
1362 | callback, you then check whether the time-out is real, or, if there was |
|
|
1363 | some activity, you reschedule the watcher to time-out in "last_activity + |
|
|
1364 | timeout - ev_now ()" seconds. |
|
|
1365 | |
1473 | |
1366 | =item ev_tstamp repeat [read-write] |
1474 | =item ev_tstamp repeat [read-write] |
1367 | |
1475 | |
1368 | The current C<repeat> value. Will be used each time the watcher times out |
1476 | The current C<repeat> value. Will be used each time the watcher times out |
1369 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1477 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1374 | =head3 Examples |
1482 | =head3 Examples |
1375 | |
1483 | |
1376 | Example: Create a timer that fires after 60 seconds. |
1484 | Example: Create a timer that fires after 60 seconds. |
1377 | |
1485 | |
1378 | static void |
1486 | static void |
1379 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1487 | one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1380 | { |
1488 | { |
1381 | .. one minute over, w is actually stopped right here |
1489 | .. one minute over, w is actually stopped right here |
1382 | } |
1490 | } |
1383 | |
1491 | |
1384 | struct ev_timer mytimer; |
1492 | ev_timer mytimer; |
1385 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1493 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1386 | ev_timer_start (loop, &mytimer); |
1494 | ev_timer_start (loop, &mytimer); |
1387 | |
1495 | |
1388 | Example: Create a timeout timer that times out after 10 seconds of |
1496 | Example: Create a timeout timer that times out after 10 seconds of |
1389 | inactivity. |
1497 | inactivity. |
1390 | |
1498 | |
1391 | static void |
1499 | static void |
1392 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1500 | timeout_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1393 | { |
1501 | { |
1394 | .. ten seconds without any activity |
1502 | .. ten seconds without any activity |
1395 | } |
1503 | } |
1396 | |
1504 | |
1397 | struct ev_timer mytimer; |
1505 | ev_timer mytimer; |
1398 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1506 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1399 | ev_timer_again (&mytimer); /* start timer */ |
1507 | ev_timer_again (&mytimer); /* start timer */ |
1400 | ev_loop (loop, 0); |
1508 | ev_loop (loop, 0); |
1401 | |
1509 | |
1402 | // and in some piece of code that gets executed on any "activity": |
1510 | // and in some piece of code that gets executed on any "activity": |
… | |
… | |
1488 | |
1596 | |
1489 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1597 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1490 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1598 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1491 | only event loop modification you are allowed to do). |
1599 | only event loop modification you are allowed to do). |
1492 | |
1600 | |
1493 | The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic |
1601 | The callback prototype is C<ev_tstamp (*reschedule_cb)(ev_periodic |
1494 | *w, ev_tstamp now)>, e.g.: |
1602 | *w, ev_tstamp now)>, e.g.: |
1495 | |
1603 | |
|
|
1604 | static ev_tstamp |
1496 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1605 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
1497 | { |
1606 | { |
1498 | return now + 60.; |
1607 | return now + 60.; |
1499 | } |
1608 | } |
1500 | |
1609 | |
1501 | It must return the next time to trigger, based on the passed time value |
1610 | It must return the next time to trigger, based on the passed time value |
… | |
… | |
1538 | |
1647 | |
1539 | The current interval value. Can be modified any time, but changes only |
1648 | The current interval value. Can be modified any time, but changes only |
1540 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1649 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1541 | called. |
1650 | called. |
1542 | |
1651 | |
1543 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1652 | =item ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write] |
1544 | |
1653 | |
1545 | The current reschedule callback, or C<0>, if this functionality is |
1654 | The current reschedule callback, or C<0>, if this functionality is |
1546 | switched off. Can be changed any time, but changes only take effect when |
1655 | switched off. Can be changed any time, but changes only take effect when |
1547 | the periodic timer fires or C<ev_periodic_again> is being called. |
1656 | the periodic timer fires or C<ev_periodic_again> is being called. |
1548 | |
1657 | |
… | |
… | |
1553 | Example: Call a callback every hour, or, more precisely, whenever the |
1662 | Example: Call a callback every hour, or, more precisely, whenever the |
1554 | system time is divisible by 3600. The callback invocation times have |
1663 | system time is divisible by 3600. The callback invocation times have |
1555 | potentially a lot of jitter, but good long-term stability. |
1664 | potentially a lot of jitter, but good long-term stability. |
1556 | |
1665 | |
1557 | static void |
1666 | static void |
1558 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1667 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
1559 | { |
1668 | { |
1560 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1669 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1561 | } |
1670 | } |
1562 | |
1671 | |
1563 | struct ev_periodic hourly_tick; |
1672 | ev_periodic hourly_tick; |
1564 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1673 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1565 | ev_periodic_start (loop, &hourly_tick); |
1674 | ev_periodic_start (loop, &hourly_tick); |
1566 | |
1675 | |
1567 | Example: The same as above, but use a reschedule callback to do it: |
1676 | Example: The same as above, but use a reschedule callback to do it: |
1568 | |
1677 | |
1569 | #include <math.h> |
1678 | #include <math.h> |
1570 | |
1679 | |
1571 | static ev_tstamp |
1680 | static ev_tstamp |
1572 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1681 | my_scheduler_cb (ev_periodic *w, ev_tstamp now) |
1573 | { |
1682 | { |
1574 | return now + (3600. - fmod (now, 3600.)); |
1683 | return now + (3600. - fmod (now, 3600.)); |
1575 | } |
1684 | } |
1576 | |
1685 | |
1577 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1686 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1578 | |
1687 | |
1579 | Example: Call a callback every hour, starting now: |
1688 | Example: Call a callback every hour, starting now: |
1580 | |
1689 | |
1581 | struct ev_periodic hourly_tick; |
1690 | ev_periodic hourly_tick; |
1582 | ev_periodic_init (&hourly_tick, clock_cb, |
1691 | ev_periodic_init (&hourly_tick, clock_cb, |
1583 | fmod (ev_now (loop), 3600.), 3600., 0); |
1692 | fmod (ev_now (loop), 3600.), 3600., 0); |
1584 | ev_periodic_start (loop, &hourly_tick); |
1693 | ev_periodic_start (loop, &hourly_tick); |
1585 | |
1694 | |
1586 | |
1695 | |
… | |
… | |
1628 | =head3 Examples |
1737 | =head3 Examples |
1629 | |
1738 | |
1630 | Example: Try to exit cleanly on SIGINT. |
1739 | Example: Try to exit cleanly on SIGINT. |
1631 | |
1740 | |
1632 | static void |
1741 | static void |
1633 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1742 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1634 | { |
1743 | { |
1635 | ev_unloop (loop, EVUNLOOP_ALL); |
1744 | ev_unloop (loop, EVUNLOOP_ALL); |
1636 | } |
1745 | } |
1637 | |
1746 | |
1638 | struct ev_signal signal_watcher; |
1747 | ev_signal signal_watcher; |
1639 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1748 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1640 | ev_signal_start (loop, &signal_watcher); |
1749 | ev_signal_start (loop, &signal_watcher); |
1641 | |
1750 | |
1642 | |
1751 | |
1643 | =head2 C<ev_child> - watch out for process status changes |
1752 | =head2 C<ev_child> - watch out for process status changes |
… | |
… | |
1718 | its completion. |
1827 | its completion. |
1719 | |
1828 | |
1720 | ev_child cw; |
1829 | ev_child cw; |
1721 | |
1830 | |
1722 | static void |
1831 | static void |
1723 | child_cb (EV_P_ struct ev_child *w, int revents) |
1832 | child_cb (EV_P_ ev_child *w, int revents) |
1724 | { |
1833 | { |
1725 | ev_child_stop (EV_A_ w); |
1834 | ev_child_stop (EV_A_ w); |
1726 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1835 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1727 | } |
1836 | } |
1728 | |
1837 | |
… | |
… | |
1792 | to exchange stat structures with application programs compiled using the |
1901 | to exchange stat structures with application programs compiled using the |
1793 | default compilation environment. |
1902 | default compilation environment. |
1794 | |
1903 | |
1795 | =head3 Inotify and Kqueue |
1904 | =head3 Inotify and Kqueue |
1796 | |
1905 | |
1797 | When C<inotify (7)> support has been compiled into libev (generally only |
1906 | When C<inotify (7)> support has been compiled into libev (generally |
|
|
1907 | only available with Linux 2.6.25 or above due to bugs in earlier |
1798 | available with Linux) and present at runtime, it will be used to speed up |
1908 | implementations) and present at runtime, it will be used to speed up |
1799 | change detection where possible. The inotify descriptor will be created lazily |
1909 | change detection where possible. The inotify descriptor will be created |
1800 | when the first C<ev_stat> watcher is being started. |
1910 | lazily when the first C<ev_stat> watcher is being started. |
1801 | |
1911 | |
1802 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1912 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1803 | except that changes might be detected earlier, and in some cases, to avoid |
1913 | except that changes might be detected earlier, and in some cases, to avoid |
1804 | making regular C<stat> calls. Even in the presence of inotify support |
1914 | making regular C<stat> calls. Even in the presence of inotify support |
1805 | there are many cases where libev has to resort to regular C<stat> polling, |
1915 | there are many cases where libev has to resort to regular C<stat> polling, |
… | |
… | |
1979 | |
2089 | |
1980 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
2090 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1981 | callback, free it. Also, use no error checking, as usual. |
2091 | callback, free it. Also, use no error checking, as usual. |
1982 | |
2092 | |
1983 | static void |
2093 | static void |
1984 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
2094 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
1985 | { |
2095 | { |
1986 | free (w); |
2096 | free (w); |
1987 | // now do something you wanted to do when the program has |
2097 | // now do something you wanted to do when the program has |
1988 | // no longer anything immediate to do. |
2098 | // no longer anything immediate to do. |
1989 | } |
2099 | } |
1990 | |
2100 | |
1991 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2101 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
1992 | ev_idle_init (idle_watcher, idle_cb); |
2102 | ev_idle_init (idle_watcher, idle_cb); |
1993 | ev_idle_start (loop, idle_cb); |
2103 | ev_idle_start (loop, idle_cb); |
1994 | |
2104 | |
1995 | |
2105 | |
1996 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2106 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
… | |
… | |
2077 | |
2187 | |
2078 | static ev_io iow [nfd]; |
2188 | static ev_io iow [nfd]; |
2079 | static ev_timer tw; |
2189 | static ev_timer tw; |
2080 | |
2190 | |
2081 | static void |
2191 | static void |
2082 | io_cb (ev_loop *loop, ev_io *w, int revents) |
2192 | io_cb (struct ev_loop *loop, ev_io *w, int revents) |
2083 | { |
2193 | { |
2084 | } |
2194 | } |
2085 | |
2195 | |
2086 | // create io watchers for each fd and a timer before blocking |
2196 | // create io watchers for each fd and a timer before blocking |
2087 | static void |
2197 | static void |
2088 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2198 | adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents) |
2089 | { |
2199 | { |
2090 | int timeout = 3600000; |
2200 | int timeout = 3600000; |
2091 | struct pollfd fds [nfd]; |
2201 | struct pollfd fds [nfd]; |
2092 | // actual code will need to loop here and realloc etc. |
2202 | // actual code will need to loop here and realloc etc. |
2093 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2203 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
… | |
… | |
2108 | } |
2218 | } |
2109 | } |
2219 | } |
2110 | |
2220 | |
2111 | // stop all watchers after blocking |
2221 | // stop all watchers after blocking |
2112 | static void |
2222 | static void |
2113 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2223 | adns_check_cb (struct ev_loop *loop, ev_check *w, int revents) |
2114 | { |
2224 | { |
2115 | ev_timer_stop (loop, &tw); |
2225 | ev_timer_stop (loop, &tw); |
2116 | |
2226 | |
2117 | for (int i = 0; i < nfd; ++i) |
2227 | for (int i = 0; i < nfd; ++i) |
2118 | { |
2228 | { |
… | |
… | |
2286 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2396 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2287 | used). |
2397 | used). |
2288 | |
2398 | |
2289 | struct ev_loop *loop_hi = ev_default_init (0); |
2399 | struct ev_loop *loop_hi = ev_default_init (0); |
2290 | struct ev_loop *loop_lo = 0; |
2400 | struct ev_loop *loop_lo = 0; |
2291 | struct ev_embed embed; |
2401 | ev_embed embed; |
2292 | |
2402 | |
2293 | // see if there is a chance of getting one that works |
2403 | // see if there is a chance of getting one that works |
2294 | // (remember that a flags value of 0 means autodetection) |
2404 | // (remember that a flags value of 0 means autodetection) |
2295 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2405 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2296 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2406 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
… | |
… | |
2310 | kqueue implementation). Store the kqueue/socket-only event loop in |
2420 | kqueue implementation). Store the kqueue/socket-only event loop in |
2311 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2421 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2312 | |
2422 | |
2313 | struct ev_loop *loop = ev_default_init (0); |
2423 | struct ev_loop *loop = ev_default_init (0); |
2314 | struct ev_loop *loop_socket = 0; |
2424 | struct ev_loop *loop_socket = 0; |
2315 | struct ev_embed embed; |
2425 | ev_embed embed; |
2316 | |
2426 | |
2317 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2427 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2318 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2428 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2319 | { |
2429 | { |
2320 | ev_embed_init (&embed, 0, loop_socket); |
2430 | ev_embed_init (&embed, 0, loop_socket); |
… | |
… | |
2534 | /* doh, nothing entered */; |
2644 | /* doh, nothing entered */; |
2535 | } |
2645 | } |
2536 | |
2646 | |
2537 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2647 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2538 | |
2648 | |
2539 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
2649 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
2540 | |
2650 | |
2541 | Feeds the given event set into the event loop, as if the specified event |
2651 | Feeds the given event set into the event loop, as if the specified event |
2542 | had happened for the specified watcher (which must be a pointer to an |
2652 | had happened for the specified watcher (which must be a pointer to an |
2543 | initialised but not necessarily started event watcher). |
2653 | initialised but not necessarily started event watcher). |
2544 | |
2654 | |
2545 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
2655 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
2546 | |
2656 | |
2547 | Feed an event on the given fd, as if a file descriptor backend detected |
2657 | Feed an event on the given fd, as if a file descriptor backend detected |
2548 | the given events it. |
2658 | the given events it. |
2549 | |
2659 | |
2550 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2660 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
2551 | |
2661 | |
2552 | Feed an event as if the given signal occurred (C<loop> must be the default |
2662 | Feed an event as if the given signal occurred (C<loop> must be the default |
2553 | loop!). |
2663 | loop!). |
2554 | |
2664 | |
2555 | =back |
2665 | =back |