… | |
… | |
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 | |
… | |
… | |
710 | respectively). |
710 | respectively). |
711 | |
711 | |
712 | 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> |
713 | running when nothing else is active. |
713 | running when nothing else is active. |
714 | |
714 | |
715 | struct ev_signal exitsig; |
715 | ev_signal exitsig; |
716 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
716 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
717 | ev_signal_start (loop, &exitsig); |
717 | ev_signal_start (loop, &exitsig); |
718 | evf_unref (loop); |
718 | evf_unref (loop); |
719 | |
719 | |
720 | Example: For some weird reason, unregister the above signal handler again. |
720 | Example: For some weird reason, unregister the above signal handler again. |
… | |
… | |
786 | |
786 | |
787 | 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 |
788 | 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 |
789 | 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: |
790 | |
790 | |
791 | 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) |
792 | { |
792 | { |
793 | ev_io_stop (w); |
793 | ev_io_stop (w); |
794 | ev_unloop (loop, EVUNLOOP_ALL); |
794 | ev_unloop (loop, EVUNLOOP_ALL); |
795 | } |
795 | } |
796 | |
796 | |
797 | struct ev_loop *loop = ev_default_loop (0); |
797 | struct ev_loop *loop = ev_default_loop (0); |
798 | struct ev_io stdin_watcher; |
798 | ev_io stdin_watcher; |
799 | ev_init (&stdin_watcher, my_cb); |
799 | ev_init (&stdin_watcher, my_cb); |
800 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
800 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
801 | ev_io_start (loop, &stdin_watcher); |
801 | ev_io_start (loop, &stdin_watcher); |
802 | ev_loop (loop, 0); |
802 | ev_loop (loop, 0); |
803 | |
803 | |
… | |
… | |
894 | =item C<EV_ERROR> |
894 | =item C<EV_ERROR> |
895 | |
895 | |
896 | 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 |
897 | happen because the watcher could not be properly started because libev |
897 | happen because the watcher could not be properly started because libev |
898 | 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 | |
899 | 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 |
900 | 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. |
901 | |
905 | |
902 | 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 |
903 | 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 |
904 | 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 |
905 | 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 |
… | |
… | |
925 | which rolls both calls into one. |
929 | which rolls both calls into one. |
926 | |
930 | |
927 | 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 |
928 | (or never started) and there are no pending events outstanding. |
932 | (or never started) and there are no pending events outstanding. |
929 | |
933 | |
930 | 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, |
931 | int revents)>. |
935 | int revents)>. |
932 | |
936 | |
933 | Example: Initialise an C<ev_io> watcher in two steps. |
937 | Example: Initialise an C<ev_io> watcher in two steps. |
934 | |
938 | |
935 | ev_io w; |
939 | ev_io w; |
… | |
… | |
1060 | 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 |
1061 | data: |
1065 | data: |
1062 | |
1066 | |
1063 | struct my_io |
1067 | struct my_io |
1064 | { |
1068 | { |
1065 | struct ev_io io; |
1069 | ev_io io; |
1066 | int otherfd; |
1070 | int otherfd; |
1067 | void *somedata; |
1071 | void *somedata; |
1068 | struct whatever *mostinteresting; |
1072 | struct whatever *mostinteresting; |
1069 | }; |
1073 | }; |
1070 | |
1074 | |
… | |
… | |
1073 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
1077 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
1074 | |
1078 | |
1075 | 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 |
1076 | can cast it back to your own type: |
1080 | can cast it back to your own type: |
1077 | |
1081 | |
1078 | 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) |
1079 | { |
1083 | { |
1080 | struct my_io *w = (struct my_io *)w_; |
1084 | struct my_io *w = (struct my_io *)w_; |
1081 | ... |
1085 | ... |
1082 | } |
1086 | } |
1083 | |
1087 | |
… | |
… | |
1101 | programmers): |
1105 | programmers): |
1102 | |
1106 | |
1103 | #include <stddef.h> |
1107 | #include <stddef.h> |
1104 | |
1108 | |
1105 | static void |
1109 | static void |
1106 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
1110 | t1_cb (EV_P_ ev_timer *w, int revents) |
1107 | { |
1111 | { |
1108 | struct my_biggy big = (struct my_biggy * |
1112 | struct my_biggy big = (struct my_biggy * |
1109 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1113 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1110 | } |
1114 | } |
1111 | |
1115 | |
1112 | static void |
1116 | static void |
1113 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
1117 | t2_cb (EV_P_ ev_timer *w, int revents) |
1114 | { |
1118 | { |
1115 | struct my_biggy big = (struct my_biggy * |
1119 | struct my_biggy big = (struct my_biggy * |
1116 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1120 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1117 | } |
1121 | } |
1118 | |
1122 | |
… | |
… | |
1253 | 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 |
1254 | 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 |
1255 | attempt to read a whole line in the callback. |
1259 | attempt to read a whole line in the callback. |
1256 | |
1260 | |
1257 | static void |
1261 | static void |
1258 | 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) |
1259 | { |
1263 | { |
1260 | ev_io_stop (loop, w); |
1264 | ev_io_stop (loop, w); |
1261 | .. 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 |
1262 | } |
1266 | } |
1263 | |
1267 | |
1264 | ... |
1268 | ... |
1265 | struct ev_loop *loop = ev_default_init (0); |
1269 | struct ev_loop *loop = ev_default_init (0); |
1266 | struct ev_io stdin_readable; |
1270 | ev_io stdin_readable; |
1267 | 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); |
1268 | ev_io_start (loop, &stdin_readable); |
1272 | ev_io_start (loop, &stdin_readable); |
1269 | ev_loop (loop, 0); |
1273 | ev_loop (loop, 0); |
1270 | |
1274 | |
1271 | |
1275 | |
… | |
… | |
1282 | |
1286 | |
1283 | 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 |
1284 | 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 |
1285 | then order of execution is undefined. |
1289 | then order of execution is undefined. |
1286 | |
1290 | |
|
|
1291 | =head3 Be smart about timeouts |
|
|
1292 | |
|
|
1293 | Many real-world problems involve some kind of timeout, 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 | What follows are some ways to handle this problem, from obvious and |
|
|
1298 | inefficient to smart and efficient. |
|
|
1299 | |
|
|
1300 | In the following, a 60 second activity timeout is assumed - a timeout that |
|
|
1301 | gets reset to 60 seconds each time there is activity (e.g. each time some |
|
|
1302 | data or other life sign was received). |
|
|
1303 | |
|
|
1304 | =over 4 |
|
|
1305 | |
|
|
1306 | =item 1. Use a timer and stop, reinitialise and 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> it, initialise it |
|
|
1315 | and start it again: |
|
|
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 is |
|
|
1322 | some activity, libev will first have to remove the timer from its internal |
|
|
1323 | data structure and then add it again. Libev tries to be fast, but it's |
|
|
1324 | still not a constant-time operation. |
|
|
1325 | |
|
|
1326 | =item 2. Use a timer and re-start it with C<ev_timer_again> inactivity. |
|
|
1327 | |
|
|
1328 | This is the easiest way, and involves using C<ev_timer_again> instead of |
|
|
1329 | C<ev_timer_start>. |
|
|
1330 | |
|
|
1331 | To implement this, configure an C<ev_timer> with a C<repeat> value |
|
|
1332 | of C<60> and then call C<ev_timer_again> at start and each time you |
|
|
1333 | successfully read or write some data. If you go into an idle state where |
|
|
1334 | you do not expect data to travel on the socket, you can C<ev_timer_stop> |
|
|
1335 | the timer, and C<ev_timer_again> will automatically restart it if need be. |
|
|
1336 | |
|
|
1337 | That means you can ignore both the C<ev_timer_start> function and the |
|
|
1338 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
|
|
1339 | member and C<ev_timer_again>. |
|
|
1340 | |
|
|
1341 | At start: |
|
|
1342 | |
|
|
1343 | ev_timer_init (timer, callback); |
|
|
1344 | timer->repeat = 60.; |
|
|
1345 | ev_timer_again (loop, timer); |
|
|
1346 | |
|
|
1347 | Each time there is some activity: |
|
|
1348 | |
|
|
1349 | ev_timer_again (loop, timer); |
|
|
1350 | |
|
|
1351 | It is even possible to change the time-out on the fly, regardless of |
|
|
1352 | whether the watcher is active or not: |
|
|
1353 | |
|
|
1354 | timer->repeat = 30.; |
|
|
1355 | ev_timer_again (loop, timer); |
|
|
1356 | |
|
|
1357 | This is slightly more efficient then stopping/starting the timer each time |
|
|
1358 | you want to modify its timeout value, as libev does not have to completely |
|
|
1359 | remove and re-insert the timer from/into its internal data structure. |
|
|
1360 | |
|
|
1361 | It is, however, even simpler than the "obvious" way to do it. |
|
|
1362 | |
|
|
1363 | =item 3. Let the timer time out, but then re-arm it as required. |
|
|
1364 | |
|
|
1365 | This method is more tricky, but usually most efficient: Most timeouts are |
|
|
1366 | relatively long compared to the intervals between other activity - in |
|
|
1367 | our example, within 60 seconds, there are usually many I/O events with |
|
|
1368 | associated activity resets. |
|
|
1369 | |
|
|
1370 | In this case, it would be more efficient to leave the C<ev_timer> alone, |
|
|
1371 | but remember the time of last activity, and check for a real timeout only |
|
|
1372 | within the callback: |
|
|
1373 | |
|
|
1374 | ev_tstamp last_activity; // time of last activity |
|
|
1375 | |
|
|
1376 | static void |
|
|
1377 | callback (EV_P_ ev_timer *w, int revents) |
|
|
1378 | { |
|
|
1379 | ev_tstamp now = ev_now (EV_A); |
|
|
1380 | ev_tstamp timeout = last_activity + 60.; |
|
|
1381 | |
|
|
1382 | // if last_activity + 60. is older than now, we did time out |
|
|
1383 | if (timeout < now) |
|
|
1384 | { |
|
|
1385 | // timeout occured, take action |
|
|
1386 | } |
|
|
1387 | else |
|
|
1388 | { |
|
|
1389 | // callback was invoked, but there was some activity, re-arm |
|
|
1390 | // the watcher to fire in last_activity + 60, which is |
|
|
1391 | // guaranteed to be in the future, so "again" is positive: |
|
|
1392 | w->again = timeout - now; |
|
|
1393 | ev_timer_again (EV_A_ w); |
|
|
1394 | } |
|
|
1395 | } |
|
|
1396 | |
|
|
1397 | To summarise the callback: first calculate the real timeout (defined |
|
|
1398 | as "60 seconds after the last activity"), then check if that time has |
|
|
1399 | been reached, which means something I<did>, in fact, time out. Otherwise |
|
|
1400 | the callback was invoked too early (C<timeout> is in the future), so |
|
|
1401 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1402 | a timeout then. |
|
|
1403 | |
|
|
1404 | Note how C<ev_timer_again> is used, taking advantage of the |
|
|
1405 | C<ev_timer_again> optimisation when the timer is already running. |
|
|
1406 | |
|
|
1407 | This scheme causes more callback invocations (about one every 60 seconds |
|
|
1408 | minus half the average time between activity), but virtually no calls to |
|
|
1409 | libev to change the timeout. |
|
|
1410 | |
|
|
1411 | To start the timer, simply initialise the watcher and set C<last_activity> |
|
|
1412 | to the current time (meaning we just have some activity :), then call the |
|
|
1413 | callback, which will "do the right thing" and start the timer: |
|
|
1414 | |
|
|
1415 | ev_timer_init (timer, callback); |
|
|
1416 | last_activity = ev_now (loop); |
|
|
1417 | callback (loop, timer, EV_TIMEOUT); |
|
|
1418 | |
|
|
1419 | And when there is some activity, simply store the current time in |
|
|
1420 | C<last_activity>, no libev calls at all: |
|
|
1421 | |
|
|
1422 | last_actiivty = ev_now (loop); |
|
|
1423 | |
|
|
1424 | This technique is slightly more complex, but in most cases where the |
|
|
1425 | time-out is unlikely to be triggered, much more efficient. |
|
|
1426 | |
|
|
1427 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1428 | callback :) - just change the timeout and invoke the callback, which will |
|
|
1429 | fix things for you. |
|
|
1430 | |
|
|
1431 | =item 4. Whee, use a double-linked list for your timeouts. |
|
|
1432 | |
|
|
1433 | If there is not one request, but many thousands, all employing some kind |
|
|
1434 | of timeout with the same timeout value, then one can do even better: |
|
|
1435 | |
|
|
1436 | When starting the timeout, calculate the timeout value and put the timeout |
|
|
1437 | at the I<end> of the list. |
|
|
1438 | |
|
|
1439 | Then use an C<ev_timer> to fire when the timeout at the I<beginning> of |
|
|
1440 | the list is expected to fire (for example, using the technique #3). |
|
|
1441 | |
|
|
1442 | When there is some activity, remove the timer from the list, recalculate |
|
|
1443 | the timeout, append it to the end of the list again, and make sure to |
|
|
1444 | update the C<ev_timer> if it was taken from the beginning of the list. |
|
|
1445 | |
|
|
1446 | This way, one can manage an unlimited number of timeouts in O(1) time for |
|
|
1447 | starting, stopping and updating the timers, at the expense of a major |
|
|
1448 | complication, and having to use a constant timeout. The constant timeout |
|
|
1449 | ensures that the list stays sorted. |
|
|
1450 | |
|
|
1451 | =back |
|
|
1452 | |
|
|
1453 | So what method is the best? |
|
|
1454 | |
|
|
1455 | The method #2 is a simple no-brain-required solution that is adequate in |
|
|
1456 | most situations. Method #3 requires a bit more thinking, but handles many |
|
|
1457 | cases better, and isn't very complicated either. In most case, choosing |
|
|
1458 | either one is fine. |
|
|
1459 | |
|
|
1460 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
|
|
1461 | rather complicated, but extremely efficient, something that really pays |
|
|
1462 | off after the first or so million of active timers, i.e. it's usually |
|
|
1463 | overkill :) |
|
|
1464 | |
1287 | =head3 The special problem of time updates |
1465 | =head3 The special problem of time updates |
1288 | |
1466 | |
1289 | Establishing the current time is a costly operation (it usually takes at |
1467 | Establishing the current time is a costly operation (it usually takes at |
1290 | least two system calls): EV therefore updates its idea of the current |
1468 | least two system calls): EV therefore updates its idea of the current |
1291 | time only before and after C<ev_loop> collects new events, which causes a |
1469 | time only before and after C<ev_loop> collects new events, which causes a |
… | |
… | |
1334 | If the timer is started but non-repeating, stop it (as if it timed out). |
1512 | If the timer is started but non-repeating, stop it (as if it timed out). |
1335 | |
1513 | |
1336 | If the timer is repeating, either start it if necessary (with the |
1514 | If the timer is repeating, either start it if necessary (with the |
1337 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1515 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1338 | |
1516 | |
1339 | This sounds a bit complicated, but here is a useful and typical |
1517 | This sounds a bit complicated, see "Be smart about timeouts", above, for a |
1340 | example: Imagine you have a TCP connection and you want a so-called idle |
1518 | usage example. |
1341 | timeout, that is, you want to be called when there have been, say, 60 |
|
|
1342 | seconds of inactivity on the socket. The easiest way to do this is to |
|
|
1343 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
|
|
1344 | C<ev_timer_again> each time you successfully read or write some data. If |
|
|
1345 | you go into an idle state where you do not expect data to travel on the |
|
|
1346 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
1347 | automatically restart it if need be. |
|
|
1348 | |
|
|
1349 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1350 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1351 | |
|
|
1352 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1353 | ev_timer_again (loop, timer); |
|
|
1354 | ... |
|
|
1355 | timer->again = 17.; |
|
|
1356 | ev_timer_again (loop, timer); |
|
|
1357 | ... |
|
|
1358 | timer->again = 10.; |
|
|
1359 | ev_timer_again (loop, timer); |
|
|
1360 | |
|
|
1361 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1362 | you want to modify its timeout value. |
|
|
1363 | |
|
|
1364 | Note, however, that it is often even more efficient to remember the |
|
|
1365 | time of the last activity and let the timer time-out naturally. In the |
|
|
1366 | callback, you then check whether the time-out is real, or, if there was |
|
|
1367 | some activity, you reschedule the watcher to time-out in "last_activity + |
|
|
1368 | timeout - ev_now ()" seconds. |
|
|
1369 | |
1519 | |
1370 | =item ev_tstamp repeat [read-write] |
1520 | =item ev_tstamp repeat [read-write] |
1371 | |
1521 | |
1372 | The current C<repeat> value. Will be used each time the watcher times out |
1522 | The current C<repeat> value. Will be used each time the watcher times out |
1373 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1523 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1378 | =head3 Examples |
1528 | =head3 Examples |
1379 | |
1529 | |
1380 | Example: Create a timer that fires after 60 seconds. |
1530 | Example: Create a timer that fires after 60 seconds. |
1381 | |
1531 | |
1382 | static void |
1532 | static void |
1383 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1533 | one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1384 | { |
1534 | { |
1385 | .. one minute over, w is actually stopped right here |
1535 | .. one minute over, w is actually stopped right here |
1386 | } |
1536 | } |
1387 | |
1537 | |
1388 | struct ev_timer mytimer; |
1538 | ev_timer mytimer; |
1389 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1539 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1390 | ev_timer_start (loop, &mytimer); |
1540 | ev_timer_start (loop, &mytimer); |
1391 | |
1541 | |
1392 | Example: Create a timeout timer that times out after 10 seconds of |
1542 | Example: Create a timeout timer that times out after 10 seconds of |
1393 | inactivity. |
1543 | inactivity. |
1394 | |
1544 | |
1395 | static void |
1545 | static void |
1396 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1546 | timeout_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1397 | { |
1547 | { |
1398 | .. ten seconds without any activity |
1548 | .. ten seconds without any activity |
1399 | } |
1549 | } |
1400 | |
1550 | |
1401 | struct ev_timer mytimer; |
1551 | ev_timer mytimer; |
1402 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1552 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1403 | ev_timer_again (&mytimer); /* start timer */ |
1553 | ev_timer_again (&mytimer); /* start timer */ |
1404 | ev_loop (loop, 0); |
1554 | ev_loop (loop, 0); |
1405 | |
1555 | |
1406 | // and in some piece of code that gets executed on any "activity": |
1556 | // and in some piece of code that gets executed on any "activity": |
… | |
… | |
1492 | |
1642 | |
1493 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1643 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1494 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1644 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1495 | only event loop modification you are allowed to do). |
1645 | only event loop modification you are allowed to do). |
1496 | |
1646 | |
1497 | The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic |
1647 | The callback prototype is C<ev_tstamp (*reschedule_cb)(ev_periodic |
1498 | *w, ev_tstamp now)>, e.g.: |
1648 | *w, ev_tstamp now)>, e.g.: |
1499 | |
1649 | |
|
|
1650 | static ev_tstamp |
1500 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1651 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
1501 | { |
1652 | { |
1502 | return now + 60.; |
1653 | return now + 60.; |
1503 | } |
1654 | } |
1504 | |
1655 | |
1505 | It must return the next time to trigger, based on the passed time value |
1656 | It must return the next time to trigger, based on the passed time value |
… | |
… | |
1542 | |
1693 | |
1543 | The current interval value. Can be modified any time, but changes only |
1694 | The current interval value. Can be modified any time, but changes only |
1544 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1695 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1545 | called. |
1696 | called. |
1546 | |
1697 | |
1547 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1698 | =item ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write] |
1548 | |
1699 | |
1549 | The current reschedule callback, or C<0>, if this functionality is |
1700 | The current reschedule callback, or C<0>, if this functionality is |
1550 | switched off. Can be changed any time, but changes only take effect when |
1701 | switched off. Can be changed any time, but changes only take effect when |
1551 | the periodic timer fires or C<ev_periodic_again> is being called. |
1702 | the periodic timer fires or C<ev_periodic_again> is being called. |
1552 | |
1703 | |
… | |
… | |
1557 | Example: Call a callback every hour, or, more precisely, whenever the |
1708 | Example: Call a callback every hour, or, more precisely, whenever the |
1558 | system time is divisible by 3600. The callback invocation times have |
1709 | system time is divisible by 3600. The callback invocation times have |
1559 | potentially a lot of jitter, but good long-term stability. |
1710 | potentially a lot of jitter, but good long-term stability. |
1560 | |
1711 | |
1561 | static void |
1712 | static void |
1562 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1713 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
1563 | { |
1714 | { |
1564 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1715 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1565 | } |
1716 | } |
1566 | |
1717 | |
1567 | struct ev_periodic hourly_tick; |
1718 | ev_periodic hourly_tick; |
1568 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1719 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1569 | ev_periodic_start (loop, &hourly_tick); |
1720 | ev_periodic_start (loop, &hourly_tick); |
1570 | |
1721 | |
1571 | Example: The same as above, but use a reschedule callback to do it: |
1722 | Example: The same as above, but use a reschedule callback to do it: |
1572 | |
1723 | |
1573 | #include <math.h> |
1724 | #include <math.h> |
1574 | |
1725 | |
1575 | static ev_tstamp |
1726 | static ev_tstamp |
1576 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1727 | my_scheduler_cb (ev_periodic *w, ev_tstamp now) |
1577 | { |
1728 | { |
1578 | return now + (3600. - fmod (now, 3600.)); |
1729 | return now + (3600. - fmod (now, 3600.)); |
1579 | } |
1730 | } |
1580 | |
1731 | |
1581 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1732 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1582 | |
1733 | |
1583 | Example: Call a callback every hour, starting now: |
1734 | Example: Call a callback every hour, starting now: |
1584 | |
1735 | |
1585 | struct ev_periodic hourly_tick; |
1736 | ev_periodic hourly_tick; |
1586 | ev_periodic_init (&hourly_tick, clock_cb, |
1737 | ev_periodic_init (&hourly_tick, clock_cb, |
1587 | fmod (ev_now (loop), 3600.), 3600., 0); |
1738 | fmod (ev_now (loop), 3600.), 3600., 0); |
1588 | ev_periodic_start (loop, &hourly_tick); |
1739 | ev_periodic_start (loop, &hourly_tick); |
1589 | |
1740 | |
1590 | |
1741 | |
… | |
… | |
1632 | =head3 Examples |
1783 | =head3 Examples |
1633 | |
1784 | |
1634 | Example: Try to exit cleanly on SIGINT. |
1785 | Example: Try to exit cleanly on SIGINT. |
1635 | |
1786 | |
1636 | static void |
1787 | static void |
1637 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1788 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1638 | { |
1789 | { |
1639 | ev_unloop (loop, EVUNLOOP_ALL); |
1790 | ev_unloop (loop, EVUNLOOP_ALL); |
1640 | } |
1791 | } |
1641 | |
1792 | |
1642 | struct ev_signal signal_watcher; |
1793 | ev_signal signal_watcher; |
1643 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1794 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1644 | ev_signal_start (loop, &signal_watcher); |
1795 | ev_signal_start (loop, &signal_watcher); |
1645 | |
1796 | |
1646 | |
1797 | |
1647 | =head2 C<ev_child> - watch out for process status changes |
1798 | =head2 C<ev_child> - watch out for process status changes |
… | |
… | |
1722 | its completion. |
1873 | its completion. |
1723 | |
1874 | |
1724 | ev_child cw; |
1875 | ev_child cw; |
1725 | |
1876 | |
1726 | static void |
1877 | static void |
1727 | child_cb (EV_P_ struct ev_child *w, int revents) |
1878 | child_cb (EV_P_ ev_child *w, int revents) |
1728 | { |
1879 | { |
1729 | ev_child_stop (EV_A_ w); |
1880 | ev_child_stop (EV_A_ w); |
1730 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1881 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1731 | } |
1882 | } |
1732 | |
1883 | |
… | |
… | |
1984 | |
2135 | |
1985 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
2136 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1986 | callback, free it. Also, use no error checking, as usual. |
2137 | callback, free it. Also, use no error checking, as usual. |
1987 | |
2138 | |
1988 | static void |
2139 | static void |
1989 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
2140 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
1990 | { |
2141 | { |
1991 | free (w); |
2142 | free (w); |
1992 | // now do something you wanted to do when the program has |
2143 | // now do something you wanted to do when the program has |
1993 | // no longer anything immediate to do. |
2144 | // no longer anything immediate to do. |
1994 | } |
2145 | } |
1995 | |
2146 | |
1996 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2147 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
1997 | ev_idle_init (idle_watcher, idle_cb); |
2148 | ev_idle_init (idle_watcher, idle_cb); |
1998 | ev_idle_start (loop, idle_cb); |
2149 | ev_idle_start (loop, idle_cb); |
1999 | |
2150 | |
2000 | |
2151 | |
2001 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2152 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
… | |
… | |
2082 | |
2233 | |
2083 | static ev_io iow [nfd]; |
2234 | static ev_io iow [nfd]; |
2084 | static ev_timer tw; |
2235 | static ev_timer tw; |
2085 | |
2236 | |
2086 | static void |
2237 | static void |
2087 | io_cb (ev_loop *loop, ev_io *w, int revents) |
2238 | io_cb (struct ev_loop *loop, ev_io *w, int revents) |
2088 | { |
2239 | { |
2089 | } |
2240 | } |
2090 | |
2241 | |
2091 | // create io watchers for each fd and a timer before blocking |
2242 | // create io watchers for each fd and a timer before blocking |
2092 | static void |
2243 | static void |
2093 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2244 | adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents) |
2094 | { |
2245 | { |
2095 | int timeout = 3600000; |
2246 | int timeout = 3600000; |
2096 | struct pollfd fds [nfd]; |
2247 | struct pollfd fds [nfd]; |
2097 | // actual code will need to loop here and realloc etc. |
2248 | // actual code will need to loop here and realloc etc. |
2098 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2249 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
… | |
… | |
2113 | } |
2264 | } |
2114 | } |
2265 | } |
2115 | |
2266 | |
2116 | // stop all watchers after blocking |
2267 | // stop all watchers after blocking |
2117 | static void |
2268 | static void |
2118 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2269 | adns_check_cb (struct ev_loop *loop, ev_check *w, int revents) |
2119 | { |
2270 | { |
2120 | ev_timer_stop (loop, &tw); |
2271 | ev_timer_stop (loop, &tw); |
2121 | |
2272 | |
2122 | for (int i = 0; i < nfd; ++i) |
2273 | for (int i = 0; i < nfd; ++i) |
2123 | { |
2274 | { |
… | |
… | |
2291 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2442 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2292 | used). |
2443 | used). |
2293 | |
2444 | |
2294 | struct ev_loop *loop_hi = ev_default_init (0); |
2445 | struct ev_loop *loop_hi = ev_default_init (0); |
2295 | struct ev_loop *loop_lo = 0; |
2446 | struct ev_loop *loop_lo = 0; |
2296 | struct ev_embed embed; |
2447 | ev_embed embed; |
2297 | |
2448 | |
2298 | // see if there is a chance of getting one that works |
2449 | // see if there is a chance of getting one that works |
2299 | // (remember that a flags value of 0 means autodetection) |
2450 | // (remember that a flags value of 0 means autodetection) |
2300 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2451 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2301 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2452 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
… | |
… | |
2315 | kqueue implementation). Store the kqueue/socket-only event loop in |
2466 | kqueue implementation). Store the kqueue/socket-only event loop in |
2316 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2467 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2317 | |
2468 | |
2318 | struct ev_loop *loop = ev_default_init (0); |
2469 | struct ev_loop *loop = ev_default_init (0); |
2319 | struct ev_loop *loop_socket = 0; |
2470 | struct ev_loop *loop_socket = 0; |
2320 | struct ev_embed embed; |
2471 | ev_embed embed; |
2321 | |
2472 | |
2322 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2473 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2323 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2474 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2324 | { |
2475 | { |
2325 | ev_embed_init (&embed, 0, loop_socket); |
2476 | ev_embed_init (&embed, 0, loop_socket); |
… | |
… | |
2539 | /* doh, nothing entered */; |
2690 | /* doh, nothing entered */; |
2540 | } |
2691 | } |
2541 | |
2692 | |
2542 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2693 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2543 | |
2694 | |
2544 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
2695 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
2545 | |
2696 | |
2546 | Feeds the given event set into the event loop, as if the specified event |
2697 | Feeds the given event set into the event loop, as if the specified event |
2547 | had happened for the specified watcher (which must be a pointer to an |
2698 | had happened for the specified watcher (which must be a pointer to an |
2548 | initialised but not necessarily started event watcher). |
2699 | initialised but not necessarily started event watcher). |
2549 | |
2700 | |
2550 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
2701 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
2551 | |
2702 | |
2552 | Feed an event on the given fd, as if a file descriptor backend detected |
2703 | Feed an event on the given fd, as if a file descriptor backend detected |
2553 | the given events it. |
2704 | the given events it. |
2554 | |
2705 | |
2555 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2706 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
2556 | |
2707 | |
2557 | Feed an event as if the given signal occurred (C<loop> must be the default |
2708 | Feed an event as if the given signal occurred (C<loop> must be the default |
2558 | loop!). |
2709 | loop!). |
2559 | |
2710 | |
2560 | =back |
2711 | =back |