… | |
… | |
1174 | |
1174 | |
1175 | =item C<EV_PREPARE> |
1175 | =item C<EV_PREPARE> |
1176 | |
1176 | |
1177 | =item C<EV_CHECK> |
1177 | =item C<EV_CHECK> |
1178 | |
1178 | |
1179 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1179 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to |
1180 | to gather new events, and all C<ev_check> watchers are invoked just after |
1180 | gather new events, and all C<ev_check> watchers are queued (not invoked) |
1181 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1181 | just after C<ev_run> has gathered them, but before it queues any callbacks |
|
|
1182 | for any received events. That means C<ev_prepare> watchers are the last |
|
|
1183 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1184 | C<ev_check> watchers will be invoked before any other watchers of the same |
|
|
1185 | or lower priority within an event loop iteration. |
|
|
1186 | |
1182 | received events. Callbacks of both watcher types can start and stop as |
1187 | Callbacks of both watcher types can start and stop as many watchers as |
1183 | many watchers as they want, and all of them will be taken into account |
1188 | they want, and all of them will be taken into account (for example, a |
1184 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1189 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1185 | C<ev_run> from blocking). |
1190 | blocking). |
1186 | |
1191 | |
1187 | =item C<EV_EMBED> |
1192 | =item C<EV_EMBED> |
1188 | |
1193 | |
1189 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1194 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1190 | |
1195 | |
… | |
… | |
1874 | callback (EV_P_ ev_timer *w, int revents) |
1879 | callback (EV_P_ ev_timer *w, int revents) |
1875 | { |
1880 | { |
1876 | // calculate when the timeout would happen |
1881 | // calculate when the timeout would happen |
1877 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1882 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1878 | |
1883 | |
1879 | // if negative, it means we the timeout already occured |
1884 | // if negative, it means we the timeout already occurred |
1880 | if (after < 0.) |
1885 | if (after < 0.) |
1881 | { |
1886 | { |
1882 | // timeout occurred, take action |
1887 | // timeout occurred, take action |
1883 | } |
1888 | } |
1884 | else |
1889 | else |
… | |
… | |
1902 | |
1907 | |
1903 | Otherwise, we now the earliest time at which the timeout would trigger, |
1908 | Otherwise, we now the earliest time at which the timeout would trigger, |
1904 | and simply start the timer with this timeout value. |
1909 | and simply start the timer with this timeout value. |
1905 | |
1910 | |
1906 | In other words, each time the callback is invoked it will check whether |
1911 | In other words, each time the callback is invoked it will check whether |
1907 | the timeout cocured. If not, it will simply reschedule itself to check |
1912 | the timeout occurred. If not, it will simply reschedule itself to check |
1908 | again at the earliest time it could time out. Rinse. Repeat. |
1913 | again at the earliest time it could time out. Rinse. Repeat. |
1909 | |
1914 | |
1910 | This scheme causes more callback invocations (about one every 60 seconds |
1915 | This scheme causes more callback invocations (about one every 60 seconds |
1911 | minus half the average time between activity), but virtually no calls to |
1916 | minus half the average time between activity), but virtually no calls to |
1912 | libev to change the timeout. |
1917 | libev to change the timeout. |
… | |
… | |
1926 | if (activity detected) |
1931 | if (activity detected) |
1927 | last_activity = ev_now (EV_A); |
1932 | last_activity = ev_now (EV_A); |
1928 | |
1933 | |
1929 | When your timeout value changes, then the timeout can be changed by simply |
1934 | When your timeout value changes, then the timeout can be changed by simply |
1930 | providing a new value, stopping the timer and calling the callback, which |
1935 | providing a new value, stopping the timer and calling the callback, which |
1931 | will agaion do the right thing (for example, time out immediately :). |
1936 | will again do the right thing (for example, time out immediately :). |
1932 | |
1937 | |
1933 | timeout = new_value; |
1938 | timeout = new_value; |
1934 | ev_timer_stop (EV_A_ &timer); |
1939 | ev_timer_stop (EV_A_ &timer); |
1935 | callback (EV_A_ &timer, 0); |
1940 | callback (EV_A_ &timer, 0); |
1936 | |
1941 | |
… | |
… | |
3313 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3318 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3314 | |
3319 | |
3315 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3320 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3316 | too, are asynchronous in nature, and signals, too, will be compressed |
3321 | too, are asynchronous in nature, and signals, too, will be compressed |
3317 | (i.e. the number of callback invocations may be less than the number of |
3322 | (i.e. the number of callback invocations may be less than the number of |
3318 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3323 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
3319 | of "global async watchers" by using a watcher on an otherwise unused |
3324 | of "global async watchers" by using a watcher on an otherwise unused |
3320 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3325 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3321 | even without knowing which loop owns the signal. |
3326 | even without knowing which loop owns the signal. |
3322 | |
3327 | |
3323 | =head3 Queueing |
3328 | =head3 Queueing |
… | |
… | |
3921 | |
3926 | |
3922 | ... |
3927 | ... |
3923 | ev_set_syserr_cb (fatal_error); |
3928 | ev_set_syserr_cb (fatal_error); |
3924 | |
3929 | |
3925 | The only API functions that can currently throw exceptions are C<ev_run>, |
3930 | The only API functions that can currently throw exceptions are C<ev_run>, |
3926 | C<ev_inoke> and C<ev_invoke_pending>. |
3931 | C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
|
|
3932 | because it runs cleanup watchers). |
3927 | |
3933 | |
3928 | Throwing exceptions in watcher callbacks is only supported if libev itself |
3934 | Throwing exceptions in watcher callbacks is only supported if libev itself |
3929 | is compiled with a C++ compiler or your C and C++ environments allow |
3935 | is compiled with a C++ compiler or your C and C++ environments allow |
3930 | throwing exceptions through C libraries (most do). |
3936 | throwing exceptions through C libraries (most do). |
3931 | |
3937 | |