… | |
… | |
118 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
119 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
120 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
121 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
122 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
123 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
124 | this argument. |
124 | this argument. |
125 | |
125 | |
126 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
127 | |
127 | |
128 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
… | |
… | |
370 | When this flag is specified, then libev will not attempt to use the |
370 | When this flag is specified, then libev will not attempt to use the |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
374 | |
374 | |
375 | =item C<EVFLAG_NOSIGNALFD> |
375 | =item C<EVFLAG_SIGNALFD> |
376 | |
376 | |
377 | When this flag is specified, then libev will not attempt to use the |
377 | When this flag is specified, then libev will attempt to use the |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
379 | probably only useful to work around any bugs in libev. Consequently, this |
379 | delivers signals synchronously, which makes it both faster and might make |
380 | flag might go away once the signalfd functionality is considered stable, |
380 | it possible to get the queued signal data. It can also simplify signal |
381 | so it's useful mostly in environment variables and not in program code. |
381 | handling with threads, as long as you properly block signals in your |
|
|
382 | threads that are not interested in handling them. |
|
|
383 | |
|
|
384 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
385 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
386 | example) that can't properly initialise their signal masks. |
382 | |
387 | |
383 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
384 | |
389 | |
385 | This is your standard select(2) backend. Not I<completely> standard, as |
390 | This is your standard select(2) backend. Not I<completely> standard, as |
386 | libev tries to roll its own fd_set with no limits on the number of fds, |
391 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
410 | |
415 | |
411 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
416 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
412 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
417 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
413 | |
418 | |
414 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
419 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
420 | |
|
|
421 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
422 | kernels). |
415 | |
423 | |
416 | For few fds, this backend is a bit little slower than poll and select, |
424 | For few fds, this backend is a bit little slower than poll and select, |
417 | but it scales phenomenally better. While poll and select usually scale |
425 | but it scales phenomenally better. While poll and select usually scale |
418 | like O(total_fds) where n is the total number of fds (or the highest fd), |
426 | like O(total_fds) where n is the total number of fds (or the highest fd), |
419 | epoll scales either O(1) or O(active_fds). |
427 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
559 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
567 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
560 | |
568 | |
561 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
569 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
562 | |
570 | |
563 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
571 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
564 | always distinct from the default loop. Unlike the default loop, it cannot |
572 | always distinct from the default loop. |
565 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
566 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
567 | |
573 | |
568 | Note that this function I<is> thread-safe, and the recommended way to use |
574 | Note that this function I<is> thread-safe, and one common way to use |
569 | libev with threads is indeed to create one loop per thread, and using the |
575 | libev with threads is indeed to create one loop per thread, and using the |
570 | default loop in the "main" or "initial" thread. |
576 | default loop in the "main" or "initial" thread. |
571 | |
577 | |
572 | Example: Try to create a event loop that uses epoll and nothing else. |
578 | Example: Try to create a event loop that uses epoll and nothing else. |
573 | |
579 | |
… | |
… | |
575 | if (!epoller) |
581 | if (!epoller) |
576 | fatal ("no epoll found here, maybe it hides under your chair"); |
582 | fatal ("no epoll found here, maybe it hides under your chair"); |
577 | |
583 | |
578 | =item ev_default_destroy () |
584 | =item ev_default_destroy () |
579 | |
585 | |
580 | Destroys the default loop again (frees all memory and kernel state |
586 | Destroys the default loop (frees all memory and kernel state etc.). None |
581 | etc.). None of the active event watchers will be stopped in the normal |
587 | of the active event watchers will be stopped in the normal sense, so |
582 | sense, so e.g. C<ev_is_active> might still return true. It is your |
588 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
583 | responsibility to either stop all watchers cleanly yourself I<before> |
589 | either stop all watchers cleanly yourself I<before> calling this function, |
584 | calling this function, or cope with the fact afterwards (which is usually |
590 | or cope with the fact afterwards (which is usually the easiest thing, you |
585 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
591 | can just ignore the watchers and/or C<free ()> them for example). |
586 | for example). |
|
|
587 | |
592 | |
588 | Note that certain global state, such as signal state (and installed signal |
593 | Note that certain global state, such as signal state (and installed signal |
589 | handlers), will not be freed by this function, and related watchers (such |
594 | handlers), will not be freed by this function, and related watchers (such |
590 | as signal and child watchers) would need to be stopped manually. |
595 | as signal and child watchers) would need to be stopped manually. |
591 | |
596 | |
592 | In general it is not advisable to call this function except in the |
597 | In general it is not advisable to call this function except in the |
593 | rare occasion where you really need to free e.g. the signal handling |
598 | rare occasion where you really need to free e.g. the signal handling |
594 | pipe fds. If you need dynamically allocated loops it is better to use |
599 | pipe fds. If you need dynamically allocated loops it is better to use |
595 | C<ev_loop_new> and C<ev_loop_destroy>). |
600 | C<ev_loop_new> and C<ev_loop_destroy>. |
596 | |
601 | |
597 | =item ev_loop_destroy (loop) |
602 | =item ev_loop_destroy (loop) |
598 | |
603 | |
599 | Like C<ev_default_destroy>, but destroys an event loop created by an |
604 | Like C<ev_default_destroy>, but destroys an event loop created by an |
600 | earlier call to C<ev_loop_new>. |
605 | earlier call to C<ev_loop_new>. |
… | |
… | |
704 | event loop time (see C<ev_now_update>). |
709 | event loop time (see C<ev_now_update>). |
705 | |
710 | |
706 | =item ev_loop (loop, int flags) |
711 | =item ev_loop (loop, int flags) |
707 | |
712 | |
708 | Finally, this is it, the event handler. This function usually is called |
713 | Finally, this is it, the event handler. This function usually is called |
709 | after you initialised all your watchers and you want to start handling |
714 | after you have initialised all your watchers and you want to start |
710 | events. |
715 | handling events. |
711 | |
716 | |
712 | If the flags argument is specified as C<0>, it will not return until |
717 | If the flags argument is specified as C<0>, it will not return until |
713 | either no event watchers are active anymore or C<ev_unloop> was called. |
718 | either no event watchers are active anymore or C<ev_unloop> was called. |
714 | |
719 | |
715 | Please note that an explicit C<ev_unloop> is usually better than |
720 | Please note that an explicit C<ev_unloop> is usually better than |
… | |
… | |
789 | |
794 | |
790 | Ref/unref can be used to add or remove a reference count on the event |
795 | Ref/unref can be used to add or remove a reference count on the event |
791 | loop: Every watcher keeps one reference, and as long as the reference |
796 | loop: Every watcher keeps one reference, and as long as the reference |
792 | count is nonzero, C<ev_loop> will not return on its own. |
797 | count is nonzero, C<ev_loop> will not return on its own. |
793 | |
798 | |
794 | If you have a watcher you never unregister that should not keep C<ev_loop> |
799 | This is useful when you have a watcher that you never intend to |
795 | from returning, call ev_unref() after starting, and ev_ref() before |
800 | unregister, but that nevertheless should not keep C<ev_loop> from |
|
|
801 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
796 | stopping it. |
802 | before stopping it. |
797 | |
803 | |
798 | As an example, libev itself uses this for its internal signal pipe: It |
804 | As an example, libev itself uses this for its internal signal pipe: It |
799 | is not visible to the libev user and should not keep C<ev_loop> from |
805 | is not visible to the libev user and should not keep C<ev_loop> from |
800 | exiting if no event watchers registered by it are active. It is also an |
806 | exiting if no event watchers registered by it are active. It is also an |
801 | excellent way to do this for generic recurring timers or from within |
807 | excellent way to do this for generic recurring timers or from within |
… | |
… | |
916 | |
922 | |
917 | While event loop modifications are allowed between invocations of |
923 | While event loop modifications are allowed between invocations of |
918 | C<release> and C<acquire> (that's their only purpose after all), no |
924 | C<release> and C<acquire> (that's their only purpose after all), no |
919 | modifications done will affect the event loop, i.e. adding watchers will |
925 | modifications done will affect the event loop, i.e. adding watchers will |
920 | have no effect on the set of file descriptors being watched, or the time |
926 | have no effect on the set of file descriptors being watched, or the time |
921 | waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it |
927 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
922 | to take note of any changes you made. |
928 | to take note of any changes you made. |
923 | |
929 | |
924 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
930 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
925 | invocations of C<release> and C<acquire>. |
931 | invocations of C<release> and C<acquire>. |
926 | |
932 | |
… | |
… | |
1023 | =item C<EV_WRITE> |
1029 | =item C<EV_WRITE> |
1024 | |
1030 | |
1025 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1031 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1026 | writable. |
1032 | writable. |
1027 | |
1033 | |
1028 | =item C<EV_TIMEOUT> |
1034 | =item C<EV_TIMER> |
1029 | |
1035 | |
1030 | The C<ev_timer> watcher has timed out. |
1036 | The C<ev_timer> watcher has timed out. |
1031 | |
1037 | |
1032 | =item C<EV_PERIODIC> |
1038 | =item C<EV_PERIODIC> |
1033 | |
1039 | |
… | |
… | |
1123 | |
1129 | |
1124 | ev_io w; |
1130 | ev_io w; |
1125 | ev_init (&w, my_cb); |
1131 | ev_init (&w, my_cb); |
1126 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1132 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1127 | |
1133 | |
1128 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1134 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1129 | |
1135 | |
1130 | This macro initialises the type-specific parts of a watcher. You need to |
1136 | This macro initialises the type-specific parts of a watcher. You need to |
1131 | call C<ev_init> at least once before you call this macro, but you can |
1137 | call C<ev_init> at least once before you call this macro, but you can |
1132 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1138 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1133 | macro on a watcher that is active (it can be pending, however, which is a |
1139 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1146 | |
1152 | |
1147 | Example: Initialise and set an C<ev_io> watcher in one step. |
1153 | Example: Initialise and set an C<ev_io> watcher in one step. |
1148 | |
1154 | |
1149 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1155 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1150 | |
1156 | |
1151 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1157 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1152 | |
1158 | |
1153 | Starts (activates) the given watcher. Only active watchers will receive |
1159 | Starts (activates) the given watcher. Only active watchers will receive |
1154 | events. If the watcher is already active nothing will happen. |
1160 | events. If the watcher is already active nothing will happen. |
1155 | |
1161 | |
1156 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1162 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1157 | whole section. |
1163 | whole section. |
1158 | |
1164 | |
1159 | ev_io_start (EV_DEFAULT_UC, &w); |
1165 | ev_io_start (EV_DEFAULT_UC, &w); |
1160 | |
1166 | |
1161 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1167 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1162 | |
1168 | |
1163 | Stops the given watcher if active, and clears the pending status (whether |
1169 | Stops the given watcher if active, and clears the pending status (whether |
1164 | the watcher was active or not). |
1170 | the watcher was active or not). |
1165 | |
1171 | |
1166 | It is possible that stopped watchers are pending - for example, |
1172 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1191 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1197 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1192 | |
1198 | |
1193 | Change the callback. You can change the callback at virtually any time |
1199 | Change the callback. You can change the callback at virtually any time |
1194 | (modulo threads). |
1200 | (modulo threads). |
1195 | |
1201 | |
1196 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1202 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1197 | |
1203 | |
1198 | =item int ev_priority (ev_TYPE *watcher) |
1204 | =item int ev_priority (ev_TYPE *watcher) |
1199 | |
1205 | |
1200 | Set and query the priority of the watcher. The priority is a small |
1206 | Set and query the priority of the watcher. The priority is a small |
1201 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1207 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1232 | returns its C<revents> bitset (as if its callback was invoked). If the |
1238 | returns its C<revents> bitset (as if its callback was invoked). If the |
1233 | watcher isn't pending it does nothing and returns C<0>. |
1239 | watcher isn't pending it does nothing and returns C<0>. |
1234 | |
1240 | |
1235 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1241 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1236 | callback to be invoked, which can be accomplished with this function. |
1242 | callback to be invoked, which can be accomplished with this function. |
|
|
1243 | |
|
|
1244 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1245 | |
|
|
1246 | Feeds the given event set into the event loop, as if the specified event |
|
|
1247 | had happened for the specified watcher (which must be a pointer to an |
|
|
1248 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1249 | not free the watcher as long as it has pending events. |
|
|
1250 | |
|
|
1251 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1252 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1253 | not started in the first place. |
|
|
1254 | |
|
|
1255 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1256 | functions that do not need a watcher. |
1237 | |
1257 | |
1238 | =back |
1258 | =back |
1239 | |
1259 | |
1240 | |
1260 | |
1241 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1261 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1515 | |
1535 | |
1516 | So when you encounter spurious, unexplained daemon exits, make sure you |
1536 | So when you encounter spurious, unexplained daemon exits, make sure you |
1517 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1537 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1518 | somewhere, as that would have given you a big clue). |
1538 | somewhere, as that would have given you a big clue). |
1519 | |
1539 | |
|
|
1540 | =head3 The special problem of accept()ing when you can't |
|
|
1541 | |
|
|
1542 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1543 | found in port-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1544 | connection from the pending queue in all error cases. |
|
|
1545 | |
|
|
1546 | For example, larger servers often run out of file descriptors (because |
|
|
1547 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1548 | rejecting the connection, leading to libev signalling readiness on |
|
|
1549 | the next iteration again (the connection still exists after all), and |
|
|
1550 | typically causing the program to loop at 100% CPU usage. |
|
|
1551 | |
|
|
1552 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1553 | operating systems, there is usually little the app can do to remedy the |
|
|
1554 | situation, and no known thread-safe method of removing the connection to |
|
|
1555 | cope with overload is known (to me). |
|
|
1556 | |
|
|
1557 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1558 | - when the program encounters an overload, it will just loop until the |
|
|
1559 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1560 | event-based way to handle this situation, so it's the best one can do. |
|
|
1561 | |
|
|
1562 | A better way to handle the situation is to log any errors other than |
|
|
1563 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1564 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1565 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1566 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1567 | usage. |
|
|
1568 | |
|
|
1569 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1570 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1571 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1572 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1573 | clients under typical overload conditions. |
|
|
1574 | |
|
|
1575 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1576 | is often done with C<malloc> failures, but this results in an easy |
|
|
1577 | opportunity for a DoS attack. |
1520 | |
1578 | |
1521 | =head3 Watcher-Specific Functions |
1579 | =head3 Watcher-Specific Functions |
1522 | |
1580 | |
1523 | =over 4 |
1581 | =over 4 |
1524 | |
1582 | |
… | |
… | |
1703 | to the current time (meaning we just have some activity :), then call the |
1761 | to the current time (meaning we just have some activity :), then call the |
1704 | callback, which will "do the right thing" and start the timer: |
1762 | callback, which will "do the right thing" and start the timer: |
1705 | |
1763 | |
1706 | ev_init (timer, callback); |
1764 | ev_init (timer, callback); |
1707 | last_activity = ev_now (loop); |
1765 | last_activity = ev_now (loop); |
1708 | callback (loop, timer, EV_TIMEOUT); |
1766 | callback (loop, timer, EV_TIMER); |
1709 | |
1767 | |
1710 | And when there is some activity, simply store the current time in |
1768 | And when there is some activity, simply store the current time in |
1711 | C<last_activity>, no libev calls at all: |
1769 | C<last_activity>, no libev calls at all: |
1712 | |
1770 | |
1713 | last_actiivty = ev_now (loop); |
1771 | last_actiivty = ev_now (loop); |
… | |
… | |
1837 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1895 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1838 | |
1896 | |
1839 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1897 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1840 | usage example. |
1898 | usage example. |
1841 | |
1899 | |
1842 | =item ev_timer_remaining (loop, ev_timer *) |
1900 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
1843 | |
1901 | |
1844 | Returns the remaining time until a timer fires. If the timer is active, |
1902 | Returns the remaining time until a timer fires. If the timer is active, |
1845 | then this time is relative to the current event loop time, otherwise it's |
1903 | then this time is relative to the current event loop time, otherwise it's |
1846 | the timeout value currently configured. |
1904 | the timeout value currently configured. |
1847 | |
1905 | |
1848 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1906 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1849 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
1907 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
1850 | will return C<4>. When the timer expires and is restarted, it will return |
1908 | will return C<4>. When the timer expires and is restarted, it will return |
1851 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1909 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1852 | too), and so on. |
1910 | too), and so on. |
1853 | |
1911 | |
1854 | =item ev_tstamp repeat [read-write] |
1912 | =item ev_tstamp repeat [read-write] |
… | |
… | |
2114 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2172 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2115 | not be unduly interrupted. If you have a problem with system calls getting |
2173 | not be unduly interrupted. If you have a problem with system calls getting |
2116 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2174 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2117 | and unblock them in an C<ev_prepare> watcher. |
2175 | and unblock them in an C<ev_prepare> watcher. |
2118 | |
2176 | |
2119 | =head3 The special problem of inheritance over execve |
2177 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2120 | |
2178 | |
2121 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2179 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2122 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2180 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2123 | stopping it again), that is, libev might or might not block the signal, |
2181 | stopping it again), that is, libev might or might not block the signal, |
2124 | and might or might not set or restore the installed signal handler. |
2182 | and might or might not set or restore the installed signal handler. |
… | |
… | |
2130 | |
2188 | |
2131 | This means that before calling C<exec> (from the child) you should reset |
2189 | This means that before calling C<exec> (from the child) you should reset |
2132 | the signal mask to whatever "default" you expect (all clear is a good |
2190 | the signal mask to whatever "default" you expect (all clear is a good |
2133 | choice usually). |
2191 | choice usually). |
2134 | |
2192 | |
2135 | In current versions of libev, you can ensure that the signal mask is not |
2193 | The simplest way to ensure that the signal mask is reset in the child is |
2136 | blocking any signals (except temporarily, so thread users watch out) by |
2194 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2137 | specifying the C<EVFLAG_NOSIGNALFD> when creating the event loop. This is |
2195 | catch fork calls done by libraries (such as the libc) as well. |
2138 | not guaranteed for future versions, however. |
2196 | |
|
|
2197 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2198 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2199 | the window of opportunity for problems, it will not go away, as libev |
|
|
2200 | I<has> to modify the signal mask, at least temporarily. |
|
|
2201 | |
|
|
2202 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2203 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2204 | is not a libev-specific thing, this is true for most event libraries. |
2139 | |
2205 | |
2140 | =head3 Watcher-Specific Functions and Data Members |
2206 | =head3 Watcher-Specific Functions and Data Members |
2141 | |
2207 | |
2142 | =over 4 |
2208 | =over 4 |
2143 | |
2209 | |
… | |
… | |
2960 | =head3 Queueing |
3026 | =head3 Queueing |
2961 | |
3027 | |
2962 | C<ev_async> does not support queueing of data in any way. The reason |
3028 | C<ev_async> does not support queueing of data in any way. The reason |
2963 | is that the author does not know of a simple (or any) algorithm for a |
3029 | is that the author does not know of a simple (or any) algorithm for a |
2964 | multiple-writer-single-reader queue that works in all cases and doesn't |
3030 | multiple-writer-single-reader queue that works in all cases and doesn't |
2965 | need elaborate support such as pthreads. |
3031 | need elaborate support such as pthreads or unportable memory access |
|
|
3032 | semantics. |
2966 | |
3033 | |
2967 | That means that if you want to queue data, you have to provide your own |
3034 | That means that if you want to queue data, you have to provide your own |
2968 | queue. But at least I can tell you how to implement locking around your |
3035 | queue. But at least I can tell you how to implement locking around your |
2969 | queue: |
3036 | queue: |
2970 | |
3037 | |
… | |
… | |
3109 | |
3176 | |
3110 | If C<timeout> is less than 0, then no timeout watcher will be |
3177 | If C<timeout> is less than 0, then no timeout watcher will be |
3111 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3178 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3112 | repeat = 0) will be started. C<0> is a valid timeout. |
3179 | repeat = 0) will be started. C<0> is a valid timeout. |
3113 | |
3180 | |
3114 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3181 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3115 | passed an C<revents> set like normal event callbacks (a combination of |
3182 | passed an C<revents> set like normal event callbacks (a combination of |
3116 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3183 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3117 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3184 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3118 | a timeout and an io event at the same time - you probably should give io |
3185 | a timeout and an io event at the same time - you probably should give io |
3119 | events precedence. |
3186 | events precedence. |
3120 | |
3187 | |
3121 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3188 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3122 | |
3189 | |
3123 | static void stdin_ready (int revents, void *arg) |
3190 | static void stdin_ready (int revents, void *arg) |
3124 | { |
3191 | { |
3125 | if (revents & EV_READ) |
3192 | if (revents & EV_READ) |
3126 | /* stdin might have data for us, joy! */; |
3193 | /* stdin might have data for us, joy! */; |
3127 | else if (revents & EV_TIMEOUT) |
3194 | else if (revents & EV_TIMER) |
3128 | /* doh, nothing entered */; |
3195 | /* doh, nothing entered */; |
3129 | } |
3196 | } |
3130 | |
3197 | |
3131 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3198 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3132 | |
3199 | |
3133 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3134 | |
|
|
3135 | Feeds the given event set into the event loop, as if the specified event |
|
|
3136 | had happened for the specified watcher (which must be a pointer to an |
|
|
3137 | initialised but not necessarily started event watcher). |
|
|
3138 | |
|
|
3139 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3200 | =item ev_feed_fd_event (loop, int fd, int revents) |
3140 | |
3201 | |
3141 | Feed an event on the given fd, as if a file descriptor backend detected |
3202 | Feed an event on the given fd, as if a file descriptor backend detected |
3142 | the given events it. |
3203 | the given events it. |
3143 | |
3204 | |
3144 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3205 | =item ev_feed_signal_event (loop, int signum) |
3145 | |
3206 | |
3146 | Feed an event as if the given signal occurred (C<loop> must be the default |
3207 | Feed an event as if the given signal occurred (C<loop> must be the default |
3147 | loop!). |
3208 | loop!). |
3148 | |
3209 | |
3149 | =back |
3210 | =back |
… | |
… | |
3229 | |
3290 | |
3230 | =over 4 |
3291 | =over 4 |
3231 | |
3292 | |
3232 | =item ev::TYPE::TYPE () |
3293 | =item ev::TYPE::TYPE () |
3233 | |
3294 | |
3234 | =item ev::TYPE::TYPE (struct ev_loop *) |
3295 | =item ev::TYPE::TYPE (loop) |
3235 | |
3296 | |
3236 | =item ev::TYPE::~TYPE |
3297 | =item ev::TYPE::~TYPE |
3237 | |
3298 | |
3238 | The constructor (optionally) takes an event loop to associate the watcher |
3299 | The constructor (optionally) takes an event loop to associate the watcher |
3239 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3300 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3316 | Example: Use a plain function as callback. |
3377 | Example: Use a plain function as callback. |
3317 | |
3378 | |
3318 | static void io_cb (ev::io &w, int revents) { } |
3379 | static void io_cb (ev::io &w, int revents) { } |
3319 | iow.set <io_cb> (); |
3380 | iow.set <io_cb> (); |
3320 | |
3381 | |
3321 | =item w->set (struct ev_loop *) |
3382 | =item w->set (loop) |
3322 | |
3383 | |
3323 | Associates a different C<struct ev_loop> with this watcher. You can only |
3384 | Associates a different C<struct ev_loop> with this watcher. You can only |
3324 | do this when the watcher is inactive (and not pending either). |
3385 | do this when the watcher is inactive (and not pending either). |
3325 | |
3386 | |
3326 | =item w->set ([arguments]) |
3387 | =item w->set ([arguments]) |
… | |
… | |
3425 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3486 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3426 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3487 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3427 | |
3488 | |
3428 | =item Lua |
3489 | =item Lua |
3429 | |
3490 | |
3430 | Brian Maher has written a partial interface to libev |
3491 | Brian Maher has written a partial interface to libev for lua (at the |
3431 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3492 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3432 | L<http://github.com/brimworks/lua-ev>. |
3493 | L<http://github.com/brimworks/lua-ev>. |
3433 | |
3494 | |
3434 | =back |
3495 | =back |
3435 | |
3496 | |
3436 | |
3497 | |
… | |
… | |
3591 | libev.m4 |
3652 | libev.m4 |
3592 | |
3653 | |
3593 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3654 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3594 | |
3655 | |
3595 | Libev can be configured via a variety of preprocessor symbols you have to |
3656 | Libev can be configured via a variety of preprocessor symbols you have to |
3596 | define before including any of its files. The default in the absence of |
3657 | define before including (or compiling) any of its files. The default in |
3597 | autoconf is documented for every option. |
3658 | the absence of autoconf is documented for every option. |
|
|
3659 | |
|
|
3660 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3661 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3662 | to redefine them before including F<ev.h> without breakign compatibility |
|
|
3663 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3664 | users of libev and the libev code itself must be compiled with compatible |
|
|
3665 | settings. |
3598 | |
3666 | |
3599 | =over 4 |
3667 | =over 4 |
3600 | |
3668 | |
3601 | =item EV_STANDALONE |
3669 | =item EV_STANDALONE (h) |
3602 | |
3670 | |
3603 | Must always be C<1> if you do not use autoconf configuration, which |
3671 | Must always be C<1> if you do not use autoconf configuration, which |
3604 | keeps libev from including F<config.h>, and it also defines dummy |
3672 | keeps libev from including F<config.h>, and it also defines dummy |
3605 | implementations for some libevent functions (such as logging, which is not |
3673 | implementations for some libevent functions (such as logging, which is not |
3606 | supported). It will also not define any of the structs usually found in |
3674 | supported). It will also not define any of the structs usually found in |
… | |
… | |
3756 | as well as for signal and thread safety in C<ev_async> watchers. |
3824 | as well as for signal and thread safety in C<ev_async> watchers. |
3757 | |
3825 | |
3758 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3826 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3759 | (from F<signal.h>), which is usually good enough on most platforms. |
3827 | (from F<signal.h>), which is usually good enough on most platforms. |
3760 | |
3828 | |
3761 | =item EV_H |
3829 | =item EV_H (h) |
3762 | |
3830 | |
3763 | The name of the F<ev.h> header file used to include it. The default if |
3831 | The name of the F<ev.h> header file used to include it. The default if |
3764 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3832 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3765 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3833 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3766 | |
3834 | |
3767 | =item EV_CONFIG_H |
3835 | =item EV_CONFIG_H (h) |
3768 | |
3836 | |
3769 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3837 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3770 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3838 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3771 | C<EV_H>, above. |
3839 | C<EV_H>, above. |
3772 | |
3840 | |
3773 | =item EV_EVENT_H |
3841 | =item EV_EVENT_H (h) |
3774 | |
3842 | |
3775 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3843 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3776 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3844 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3777 | |
3845 | |
3778 | =item EV_PROTOTYPES |
3846 | =item EV_PROTOTYPES (h) |
3779 | |
3847 | |
3780 | If defined to be C<0>, then F<ev.h> will not define any function |
3848 | If defined to be C<0>, then F<ev.h> will not define any function |
3781 | prototypes, but still define all the structs and other symbols. This is |
3849 | prototypes, but still define all the structs and other symbols. This is |
3782 | occasionally useful if you want to provide your own wrapper functions |
3850 | occasionally useful if you want to provide your own wrapper functions |
3783 | around libev functions. |
3851 | around libev functions. |
… | |
… | |
3805 | fine. |
3873 | fine. |
3806 | |
3874 | |
3807 | If your embedding application does not need any priorities, defining these |
3875 | If your embedding application does not need any priorities, defining these |
3808 | both to C<0> will save some memory and CPU. |
3876 | both to C<0> will save some memory and CPU. |
3809 | |
3877 | |
3810 | =item EV_PERIODIC_ENABLE |
3878 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3879 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3880 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3811 | |
3881 | |
3812 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3882 | If undefined or defined to be C<1> (and the platform supports it), then |
3813 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3883 | the respective watcher type is supported. If defined to be C<0>, then it |
3814 | code. |
3884 | is not. Disabling watcher types mainly saves codesize. |
3815 | |
3885 | |
3816 | =item EV_IDLE_ENABLE |
3886 | =item EV_FEATURES |
3817 | |
|
|
3818 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3819 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3820 | code. |
|
|
3821 | |
|
|
3822 | =item EV_EMBED_ENABLE |
|
|
3823 | |
|
|
3824 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3825 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3826 | watcher types, which therefore must not be disabled. |
|
|
3827 | |
|
|
3828 | =item EV_STAT_ENABLE |
|
|
3829 | |
|
|
3830 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3831 | defined to be C<0>, then they are not. |
|
|
3832 | |
|
|
3833 | =item EV_FORK_ENABLE |
|
|
3834 | |
|
|
3835 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3836 | defined to be C<0>, then they are not. |
|
|
3837 | |
|
|
3838 | =item EV_ASYNC_ENABLE |
|
|
3839 | |
|
|
3840 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3841 | defined to be C<0>, then they are not. |
|
|
3842 | |
|
|
3843 | =item EV_MINIMAL |
|
|
3844 | |
3887 | |
3845 | If you need to shave off some kilobytes of code at the expense of some |
3888 | If you need to shave off some kilobytes of code at the expense of some |
3846 | speed (but with the full API), define this symbol to C<1>. Currently this |
3889 | speed (but with the full API), you can define this symbol to request |
3847 | is used to override some inlining decisions, saves roughly 30% code size |
3890 | certain subsets of functionality. The default is to enable all features |
3848 | on amd64. It also selects a much smaller 2-heap for timer management over |
3891 | that can be enabled on the platform. |
3849 | the default 4-heap. |
|
|
3850 | |
3892 | |
3851 | You can save even more by disabling watcher types you do not need |
3893 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3852 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
3894 | with some broad features you want) and then selectively re-enable |
3853 | (C<-DNDEBUG>) will usually reduce code size a lot. |
3895 | additional parts you want, for example if you want everything minimal, |
|
|
3896 | but multiple event loop support, async and child watchers and the poll |
|
|
3897 | backend, use this: |
3854 | |
3898 | |
3855 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3899 | #define EV_FEATURES 0 |
3856 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3900 | #define EV_MULTIPLICITY 1 |
3857 | of the API are still available, and do not complain if this subset changes |
3901 | #define EV_USE_POLL 1 |
3858 | over time. |
3902 | #define EV_CHILD_ENABLE 1 |
|
|
3903 | #define EV_ASYNC_ENABLE 1 |
|
|
3904 | |
|
|
3905 | The actual value is a bitset, it can be a combination of the following |
|
|
3906 | values: |
|
|
3907 | |
|
|
3908 | =over 4 |
|
|
3909 | |
|
|
3910 | =item C<1> - faster/larger code |
|
|
3911 | |
|
|
3912 | Use larger code to speed up some operations. |
|
|
3913 | |
|
|
3914 | Currently this is used to override some inlining decisions (enlarging the roughly |
|
|
3915 | 30% code size on amd64. |
|
|
3916 | |
|
|
3917 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
3918 | gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
3919 | assertions. |
|
|
3920 | |
|
|
3921 | =item C<2> - faster/larger data structures |
|
|
3922 | |
|
|
3923 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
3924 | hash table sizes and so on. This will usually further increase codesize |
|
|
3925 | and can additionally have an effect on the size of data structures at |
|
|
3926 | runtime. |
|
|
3927 | |
|
|
3928 | =item C<4> - full API configuration |
|
|
3929 | |
|
|
3930 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
3931 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
3932 | |
|
|
3933 | =item C<8> - full API |
|
|
3934 | |
|
|
3935 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
3936 | details on which parts of the API are still available without this |
|
|
3937 | feature, and do not complain if this subset changes over time. |
|
|
3938 | |
|
|
3939 | =item C<16> - enable all optional watcher types |
|
|
3940 | |
|
|
3941 | Enables all optional watcher types. If you want to selectively enable |
|
|
3942 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
3943 | embed, async, child...) you can enable them manually by defining |
|
|
3944 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
3945 | |
|
|
3946 | =item C<32> - enable all backends |
|
|
3947 | |
|
|
3948 | This enables all backends - without this feature, you need to enable at |
|
|
3949 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
3950 | |
|
|
3951 | =item C<64> - enable OS-specific "helper" APIs |
|
|
3952 | |
|
|
3953 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
3954 | default. |
|
|
3955 | |
|
|
3956 | =back |
|
|
3957 | |
|
|
3958 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
3959 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
3960 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
3961 | watchers, timers and monotonic clock support. |
|
|
3962 | |
|
|
3963 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
3964 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
3965 | your program might be left out as well - a binary starting a timer and an |
|
|
3966 | I/O watcher then might come out at only 5Kb. |
|
|
3967 | |
|
|
3968 | =item EV_AVOID_STDIO |
|
|
3969 | |
|
|
3970 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
3971 | functions (printf, scanf, perror etc.). This will increase the codesize |
|
|
3972 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
3973 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
3974 | big. |
|
|
3975 | |
|
|
3976 | Note that error messages might become less precise when this option is |
|
|
3977 | enabled. |
3859 | |
3978 | |
3860 | =item EV_NSIG |
3979 | =item EV_NSIG |
3861 | |
3980 | |
3862 | The highest supported signal number, +1 (or, the number of |
3981 | The highest supported signal number, +1 (or, the number of |
3863 | signals): Normally, libev tries to deduce the maximum number of signals |
3982 | signals): Normally, libev tries to deduce the maximum number of signals |
… | |
… | |
3867 | statically allocates some 12-24 bytes per signal number. |
3986 | statically allocates some 12-24 bytes per signal number. |
3868 | |
3987 | |
3869 | =item EV_PID_HASHSIZE |
3988 | =item EV_PID_HASHSIZE |
3870 | |
3989 | |
3871 | C<ev_child> watchers use a small hash table to distribute workload by |
3990 | C<ev_child> watchers use a small hash table to distribute workload by |
3872 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3991 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3873 | than enough. If you need to manage thousands of children you might want to |
3992 | usually more than enough. If you need to manage thousands of children you |
3874 | increase this value (I<must> be a power of two). |
3993 | might want to increase this value (I<must> be a power of two). |
3875 | |
3994 | |
3876 | =item EV_INOTIFY_HASHSIZE |
3995 | =item EV_INOTIFY_HASHSIZE |
3877 | |
3996 | |
3878 | C<ev_stat> watchers use a small hash table to distribute workload by |
3997 | C<ev_stat> watchers use a small hash table to distribute workload by |
3879 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
3998 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3880 | usually more than enough. If you need to manage thousands of C<ev_stat> |
3999 | disabled), usually more than enough. If you need to manage thousands of |
3881 | watchers you might want to increase this value (I<must> be a power of |
4000 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3882 | two). |
4001 | power of two). |
3883 | |
4002 | |
3884 | =item EV_USE_4HEAP |
4003 | =item EV_USE_4HEAP |
3885 | |
4004 | |
3886 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4005 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3887 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4006 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3888 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4007 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3889 | faster performance with many (thousands) of watchers. |
4008 | faster performance with many (thousands) of watchers. |
3890 | |
4009 | |
3891 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4010 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3892 | (disabled). |
4011 | will be C<0>. |
3893 | |
4012 | |
3894 | =item EV_HEAP_CACHE_AT |
4013 | =item EV_HEAP_CACHE_AT |
3895 | |
4014 | |
3896 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4015 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3897 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4016 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3898 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4017 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3899 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4018 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3900 | but avoids random read accesses on heap changes. This improves performance |
4019 | but avoids random read accesses on heap changes. This improves performance |
3901 | noticeably with many (hundreds) of watchers. |
4020 | noticeably with many (hundreds) of watchers. |
3902 | |
4021 | |
3903 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4022 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3904 | (disabled). |
4023 | will be C<0>. |
3905 | |
4024 | |
3906 | =item EV_VERIFY |
4025 | =item EV_VERIFY |
3907 | |
4026 | |
3908 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4027 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
3909 | be done: If set to C<0>, no internal verification code will be compiled |
4028 | be done: If set to C<0>, no internal verification code will be compiled |
… | |
… | |
3911 | called. If set to C<2>, then the internal verification code will be |
4030 | called. If set to C<2>, then the internal verification code will be |
3912 | called once per loop, which can slow down libev. If set to C<3>, then the |
4031 | called once per loop, which can slow down libev. If set to C<3>, then the |
3913 | verification code will be called very frequently, which will slow down |
4032 | verification code will be called very frequently, which will slow down |
3914 | libev considerably. |
4033 | libev considerably. |
3915 | |
4034 | |
3916 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4035 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3917 | C<0>. |
4036 | will be C<0>. |
3918 | |
4037 | |
3919 | =item EV_COMMON |
4038 | =item EV_COMMON |
3920 | |
4039 | |
3921 | By default, all watchers have a C<void *data> member. By redefining |
4040 | By default, all watchers have a C<void *data> member. By redefining |
3922 | this macro to a something else you can include more and other types of |
4041 | this macro to a something else you can include more and other types of |
… | |
… | |
3980 | file. |
4099 | file. |
3981 | |
4100 | |
3982 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4101 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3983 | that everybody includes and which overrides some configure choices: |
4102 | that everybody includes and which overrides some configure choices: |
3984 | |
4103 | |
3985 | #define EV_MINIMAL 1 |
4104 | #define EV_FEATURES 8 |
3986 | #define EV_USE_POLL 0 |
4105 | #define EV_USE_SELECT 1 |
3987 | #define EV_MULTIPLICITY 0 |
|
|
3988 | #define EV_PERIODIC_ENABLE 0 |
4106 | #define EV_PREPARE_ENABLE 1 |
|
|
4107 | #define EV_IDLE_ENABLE 1 |
3989 | #define EV_STAT_ENABLE 0 |
4108 | #define EV_SIGNAL_ENABLE 1 |
3990 | #define EV_FORK_ENABLE 0 |
4109 | #define EV_CHILD_ENABLE 1 |
|
|
4110 | #define EV_USE_STDEXCEPT 0 |
3991 | #define EV_CONFIG_H <config.h> |
4111 | #define EV_CONFIG_H <config.h> |
3992 | #define EV_MINPRI 0 |
|
|
3993 | #define EV_MAXPRI 0 |
|
|
3994 | |
4112 | |
3995 | #include "ev++.h" |
4113 | #include "ev++.h" |
3996 | |
4114 | |
3997 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4115 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3998 | |
4116 | |
… | |
… | |
4500 | involves iterating over all running async watchers or all signal numbers. |
4618 | involves iterating over all running async watchers or all signal numbers. |
4501 | |
4619 | |
4502 | =back |
4620 | =back |
4503 | |
4621 | |
4504 | |
4622 | |
|
|
4623 | =head1 PORTING FROM 3.X TO 4.X |
|
|
4624 | |
|
|
4625 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4626 | |
|
|
4627 | =over 4 |
|
|
4628 | |
|
|
4629 | =item C<EV_TIMEOUT> replaced by C<EV_TIMER> in C<revents> |
|
|
4630 | |
|
|
4631 | This is a simple rename - all other watcher types use their name |
|
|
4632 | as revents flag, and now C<ev_timer> does, too. |
|
|
4633 | |
|
|
4634 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4635 | and continue to be present for the forseeable future, so this is mostly a |
|
|
4636 | documentation change. |
|
|
4637 | |
|
|
4638 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4639 | |
|
|
4640 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4641 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4642 | and work, but the library code will of course be larger. |
|
|
4643 | |
|
|
4644 | =back |
|
|
4645 | |
|
|
4646 | |
4505 | =head1 GLOSSARY |
4647 | =head1 GLOSSARY |
4506 | |
4648 | |
4507 | =over 4 |
4649 | =over 4 |
4508 | |
4650 | |
4509 | =item active |
4651 | =item active |
… | |
… | |
4530 | A change of state of some external event, such as data now being available |
4672 | A change of state of some external event, such as data now being available |
4531 | for reading on a file descriptor, time having passed or simply not having |
4673 | for reading on a file descriptor, time having passed or simply not having |
4532 | any other events happening anymore. |
4674 | any other events happening anymore. |
4533 | |
4675 | |
4534 | In libev, events are represented as single bits (such as C<EV_READ> or |
4676 | In libev, events are represented as single bits (such as C<EV_READ> or |
4535 | C<EV_TIMEOUT>). |
4677 | C<EV_TIMER>). |
4536 | |
4678 | |
4537 | =item event library |
4679 | =item event library |
4538 | |
4680 | |
4539 | A software package implementing an event model and loop. |
4681 | A software package implementing an event model and loop. |
4540 | |
4682 | |