… | |
… | |
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_NOSIGFD> |
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). |
… | |
… | |
789 | |
797 | |
790 | Ref/unref can be used to add or remove a reference count on the event |
798 | 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 |
799 | 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. |
800 | count is nonzero, C<ev_loop> will not return on its own. |
793 | |
801 | |
794 | If you have a watcher you never unregister that should not keep C<ev_loop> |
802 | 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 |
803 | unregister, but that nevertheless should not keep C<ev_loop> from |
|
|
804 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
796 | stopping it. |
805 | before stopping it. |
797 | |
806 | |
798 | As an example, libev itself uses this for its internal signal pipe: It |
807 | 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 |
808 | 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 |
809 | 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 |
810 | excellent way to do this for generic recurring timers or from within |
… | |
… | |
916 | |
925 | |
917 | While event loop modifications are allowed between invocations of |
926 | While event loop modifications are allowed between invocations of |
918 | C<release> and C<acquire> (that's their only purpose after all), no |
927 | 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 |
928 | 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 |
929 | 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 |
930 | 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. |
931 | to take note of any changes you made. |
923 | |
932 | |
924 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
933 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
925 | invocations of C<release> and C<acquire>. |
934 | invocations of C<release> and C<acquire>. |
926 | |
935 | |
… | |
… | |
1123 | |
1132 | |
1124 | ev_io w; |
1133 | ev_io w; |
1125 | ev_init (&w, my_cb); |
1134 | ev_init (&w, my_cb); |
1126 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1135 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1127 | |
1136 | |
1128 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1137 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1129 | |
1138 | |
1130 | This macro initialises the type-specific parts of a watcher. You need to |
1139 | 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 |
1140 | 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 |
1141 | 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 |
1142 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1146 | |
1155 | |
1147 | Example: Initialise and set an C<ev_io> watcher in one step. |
1156 | Example: Initialise and set an C<ev_io> watcher in one step. |
1148 | |
1157 | |
1149 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1158 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1150 | |
1159 | |
1151 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1160 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1152 | |
1161 | |
1153 | Starts (activates) the given watcher. Only active watchers will receive |
1162 | Starts (activates) the given watcher. Only active watchers will receive |
1154 | events. If the watcher is already active nothing will happen. |
1163 | events. If the watcher is already active nothing will happen. |
1155 | |
1164 | |
1156 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1165 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1157 | whole section. |
1166 | whole section. |
1158 | |
1167 | |
1159 | ev_io_start (EV_DEFAULT_UC, &w); |
1168 | ev_io_start (EV_DEFAULT_UC, &w); |
1160 | |
1169 | |
1161 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1170 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1162 | |
1171 | |
1163 | Stops the given watcher if active, and clears the pending status (whether |
1172 | Stops the given watcher if active, and clears the pending status (whether |
1164 | the watcher was active or not). |
1173 | the watcher was active or not). |
1165 | |
1174 | |
1166 | It is possible that stopped watchers are pending - for example, |
1175 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1191 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1200 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1192 | |
1201 | |
1193 | Change the callback. You can change the callback at virtually any time |
1202 | Change the callback. You can change the callback at virtually any time |
1194 | (modulo threads). |
1203 | (modulo threads). |
1195 | |
1204 | |
1196 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1205 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1197 | |
1206 | |
1198 | =item int ev_priority (ev_TYPE *watcher) |
1207 | =item int ev_priority (ev_TYPE *watcher) |
1199 | |
1208 | |
1200 | Set and query the priority of the watcher. The priority is a small |
1209 | 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> |
1210 | 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 |
1241 | 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>. |
1242 | watcher isn't pending it does nothing and returns C<0>. |
1234 | |
1243 | |
1235 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1244 | 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. |
1245 | callback to be invoked, which can be accomplished with this function. |
|
|
1246 | |
|
|
1247 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1248 | |
|
|
1249 | Feeds the given event set into the event loop, as if the specified event |
|
|
1250 | had happened for the specified watcher (which must be a pointer to an |
|
|
1251 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1252 | not free the watcher as long as it has pending events. |
|
|
1253 | |
|
|
1254 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1255 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1256 | not started in the first place. |
|
|
1257 | |
|
|
1258 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1259 | functions that do not need a watcher. |
1237 | |
1260 | |
1238 | =back |
1261 | =back |
1239 | |
1262 | |
1240 | |
1263 | |
1241 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1264 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1515 | |
1538 | |
1516 | So when you encounter spurious, unexplained daemon exits, make sure you |
1539 | 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 |
1540 | 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). |
1541 | somewhere, as that would have given you a big clue). |
1519 | |
1542 | |
|
|
1543 | =head3 The special problem of accept()ing when you can't |
|
|
1544 | |
|
|
1545 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1546 | found in port-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1547 | connection from the pending queue in all error cases. |
|
|
1548 | |
|
|
1549 | For example, larger servers often run out of file descriptors (because |
|
|
1550 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1551 | rejecting the connection, leading to libev signalling readiness on |
|
|
1552 | the next iteration again (the connection still exists after all), and |
|
|
1553 | typically causing the program to loop at 100% CPU usage. |
|
|
1554 | |
|
|
1555 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1556 | operating systems, there is usually little the app can do to remedy the |
|
|
1557 | situation, and no known thread-safe method of removing the connection to |
|
|
1558 | cope with overload is known (to me). |
|
|
1559 | |
|
|
1560 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1561 | - when the program encounters an overload, it will just loop until the |
|
|
1562 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1563 | event-based way to handle this situation, so it's the best one can do. |
|
|
1564 | |
|
|
1565 | A better way to handle the situation is to log any errors other than |
|
|
1566 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1567 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1568 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1569 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1570 | usage. |
|
|
1571 | |
|
|
1572 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1573 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1574 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1575 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1576 | clients under typical overload conditions. |
|
|
1577 | |
|
|
1578 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1579 | is often done with C<malloc> failures, but this results in an easy |
|
|
1580 | opportunity for a DoS attack. |
1520 | |
1581 | |
1521 | =head3 Watcher-Specific Functions |
1582 | =head3 Watcher-Specific Functions |
1522 | |
1583 | |
1523 | =over 4 |
1584 | =over 4 |
1524 | |
1585 | |
… | |
… | |
1837 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1898 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1838 | |
1899 | |
1839 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1900 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1840 | usage example. |
1901 | usage example. |
1841 | |
1902 | |
1842 | =item ev_timer_remaining (loop, ev_timer *) |
1903 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
1843 | |
1904 | |
1844 | Returns the remaining time until a timer fires. If the timer is active, |
1905 | 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 |
1906 | then this time is relative to the current event loop time, otherwise it's |
1846 | the timeout value currently configured. |
1907 | the timeout value currently configured. |
1847 | |
1908 | |
1848 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1909 | 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> |
1910 | 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 |
1911 | 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, |
1912 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1852 | too), and so on. |
1913 | too), and so on. |
1853 | |
1914 | |
1854 | =item ev_tstamp repeat [read-write] |
1915 | =item ev_tstamp repeat [read-write] |
… | |
… | |
2114 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2175 | 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 |
2176 | 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 |
2177 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2117 | and unblock them in an C<ev_prepare> watcher. |
2178 | and unblock them in an C<ev_prepare> watcher. |
2118 | |
2179 | |
2119 | =head3 The special problem of inheritance over execve |
2180 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2120 | |
2181 | |
2121 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2182 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2122 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2183 | (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, |
2184 | 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. |
2185 | and might or might not set or restore the installed signal handler. |
… | |
… | |
2134 | |
2195 | |
2135 | The simplest way to ensure that the signal mask is reset in the child is |
2196 | The simplest way to ensure that the signal mask is reset in the child is |
2136 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2197 | to install a fork handler with C<pthread_atfork> that resets it. That will |
2137 | catch fork calls done by libraries (such as the libc) as well. |
2198 | catch fork calls done by libraries (such as the libc) as well. |
2138 | |
2199 | |
2139 | In current versions of libev, you can also ensure that the signal mask is |
2200 | In current versions of libev, the signal will not be blocked indefinitely |
2140 | not blocking any signals (except temporarily, so thread users watch out) |
2201 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
2141 | by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This |
2202 | the window of opportunity for problems, it will not go away, as libev |
2142 | is not guaranteed for future versions, however. |
2203 | I<has> to modify the signal mask, at least temporarily. |
|
|
2204 | |
|
|
2205 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2206 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2207 | is not a libev-specific thing, this is true for most event libraries. |
2143 | |
2208 | |
2144 | =head3 Watcher-Specific Functions and Data Members |
2209 | =head3 Watcher-Specific Functions and Data Members |
2145 | |
2210 | |
2146 | =over 4 |
2211 | =over 4 |
2147 | |
2212 | |
… | |
… | |
2964 | =head3 Queueing |
3029 | =head3 Queueing |
2965 | |
3030 | |
2966 | C<ev_async> does not support queueing of data in any way. The reason |
3031 | C<ev_async> does not support queueing of data in any way. The reason |
2967 | is that the author does not know of a simple (or any) algorithm for a |
3032 | is that the author does not know of a simple (or any) algorithm for a |
2968 | multiple-writer-single-reader queue that works in all cases and doesn't |
3033 | multiple-writer-single-reader queue that works in all cases and doesn't |
2969 | need elaborate support such as pthreads. |
3034 | need elaborate support such as pthreads or unportable memory access |
|
|
3035 | semantics. |
2970 | |
3036 | |
2971 | That means that if you want to queue data, you have to provide your own |
3037 | That means that if you want to queue data, you have to provide your own |
2972 | queue. But at least I can tell you how to implement locking around your |
3038 | queue. But at least I can tell you how to implement locking around your |
2973 | queue: |
3039 | queue: |
2974 | |
3040 | |
… | |
… | |
3132 | /* doh, nothing entered */; |
3198 | /* doh, nothing entered */; |
3133 | } |
3199 | } |
3134 | |
3200 | |
3135 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3201 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3136 | |
3202 | |
3137 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3138 | |
|
|
3139 | Feeds the given event set into the event loop, as if the specified event |
|
|
3140 | had happened for the specified watcher (which must be a pointer to an |
|
|
3141 | initialised but not necessarily started event watcher). |
|
|
3142 | |
|
|
3143 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3203 | =item ev_feed_fd_event (loop, int fd, int revents) |
3144 | |
3204 | |
3145 | Feed an event on the given fd, as if a file descriptor backend detected |
3205 | Feed an event on the given fd, as if a file descriptor backend detected |
3146 | the given events it. |
3206 | the given events it. |
3147 | |
3207 | |
3148 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3208 | =item ev_feed_signal_event (loop, int signum) |
3149 | |
3209 | |
3150 | Feed an event as if the given signal occurred (C<loop> must be the default |
3210 | Feed an event as if the given signal occurred (C<loop> must be the default |
3151 | loop!). |
3211 | loop!). |
3152 | |
3212 | |
3153 | =back |
3213 | =back |
… | |
… | |
3233 | |
3293 | |
3234 | =over 4 |
3294 | =over 4 |
3235 | |
3295 | |
3236 | =item ev::TYPE::TYPE () |
3296 | =item ev::TYPE::TYPE () |
3237 | |
3297 | |
3238 | =item ev::TYPE::TYPE (struct ev_loop *) |
3298 | =item ev::TYPE::TYPE (loop) |
3239 | |
3299 | |
3240 | =item ev::TYPE::~TYPE |
3300 | =item ev::TYPE::~TYPE |
3241 | |
3301 | |
3242 | The constructor (optionally) takes an event loop to associate the watcher |
3302 | The constructor (optionally) takes an event loop to associate the watcher |
3243 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3303 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3320 | Example: Use a plain function as callback. |
3380 | Example: Use a plain function as callback. |
3321 | |
3381 | |
3322 | static void io_cb (ev::io &w, int revents) { } |
3382 | static void io_cb (ev::io &w, int revents) { } |
3323 | iow.set <io_cb> (); |
3383 | iow.set <io_cb> (); |
3324 | |
3384 | |
3325 | =item w->set (struct ev_loop *) |
3385 | =item w->set (loop) |
3326 | |
3386 | |
3327 | Associates a different C<struct ev_loop> with this watcher. You can only |
3387 | Associates a different C<struct ev_loop> with this watcher. You can only |
3328 | do this when the watcher is inactive (and not pending either). |
3388 | do this when the watcher is inactive (and not pending either). |
3329 | |
3389 | |
3330 | =item w->set ([arguments]) |
3390 | =item w->set ([arguments]) |
… | |
… | |
3429 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3489 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3430 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3490 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3431 | |
3491 | |
3432 | =item Lua |
3492 | =item Lua |
3433 | |
3493 | |
3434 | Brian Maher has written a partial interface to libev |
3494 | Brian Maher has written a partial interface to libev for lua (at the |
3435 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3495 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3436 | L<http://github.com/brimworks/lua-ev>. |
3496 | L<http://github.com/brimworks/lua-ev>. |
3437 | |
3497 | |
3438 | =back |
3498 | =back |
3439 | |
3499 | |
3440 | |
3500 | |
… | |
… | |
3595 | libev.m4 |
3655 | libev.m4 |
3596 | |
3656 | |
3597 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3657 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3598 | |
3658 | |
3599 | Libev can be configured via a variety of preprocessor symbols you have to |
3659 | Libev can be configured via a variety of preprocessor symbols you have to |
3600 | define before including any of its files. The default in the absence of |
3660 | define before including (or compiling) any of its files. The default in |
3601 | autoconf is documented for every option. |
3661 | the absence of autoconf is documented for every option. |
|
|
3662 | |
|
|
3663 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3664 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3665 | to redefine them before including F<ev.h> without breakign compatibility |
|
|
3666 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3667 | users of libev and the libev code itself must be compiled with compatible |
|
|
3668 | settings. |
3602 | |
3669 | |
3603 | =over 4 |
3670 | =over 4 |
3604 | |
3671 | |
3605 | =item EV_STANDALONE |
3672 | =item EV_STANDALONE (h) |
3606 | |
3673 | |
3607 | Must always be C<1> if you do not use autoconf configuration, which |
3674 | Must always be C<1> if you do not use autoconf configuration, which |
3608 | keeps libev from including F<config.h>, and it also defines dummy |
3675 | keeps libev from including F<config.h>, and it also defines dummy |
3609 | implementations for some libevent functions (such as logging, which is not |
3676 | implementations for some libevent functions (such as logging, which is not |
3610 | supported). It will also not define any of the structs usually found in |
3677 | supported). It will also not define any of the structs usually found in |
… | |
… | |
3760 | as well as for signal and thread safety in C<ev_async> watchers. |
3827 | as well as for signal and thread safety in C<ev_async> watchers. |
3761 | |
3828 | |
3762 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3829 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3763 | (from F<signal.h>), which is usually good enough on most platforms. |
3830 | (from F<signal.h>), which is usually good enough on most platforms. |
3764 | |
3831 | |
3765 | =item EV_H |
3832 | =item EV_H (h) |
3766 | |
3833 | |
3767 | The name of the F<ev.h> header file used to include it. The default if |
3834 | The name of the F<ev.h> header file used to include it. The default if |
3768 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3835 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3769 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3836 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3770 | |
3837 | |
3771 | =item EV_CONFIG_H |
3838 | =item EV_CONFIG_H (h) |
3772 | |
3839 | |
3773 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3840 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3774 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3841 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3775 | C<EV_H>, above. |
3842 | C<EV_H>, above. |
3776 | |
3843 | |
3777 | =item EV_EVENT_H |
3844 | =item EV_EVENT_H (h) |
3778 | |
3845 | |
3779 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3846 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3780 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3847 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3781 | |
3848 | |
3782 | =item EV_PROTOTYPES |
3849 | =item EV_PROTOTYPES (h) |
3783 | |
3850 | |
3784 | If defined to be C<0>, then F<ev.h> will not define any function |
3851 | If defined to be C<0>, then F<ev.h> will not define any function |
3785 | prototypes, but still define all the structs and other symbols. This is |
3852 | prototypes, but still define all the structs and other symbols. This is |
3786 | occasionally useful if you want to provide your own wrapper functions |
3853 | occasionally useful if you want to provide your own wrapper functions |
3787 | around libev functions. |
3854 | around libev functions. |
… | |
… | |
3809 | fine. |
3876 | fine. |
3810 | |
3877 | |
3811 | If your embedding application does not need any priorities, defining these |
3878 | If your embedding application does not need any priorities, defining these |
3812 | both to C<0> will save some memory and CPU. |
3879 | both to C<0> will save some memory and CPU. |
3813 | |
3880 | |
3814 | =item EV_PERIODIC_ENABLE |
3881 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3882 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3883 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3815 | |
3884 | |
3816 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3885 | If undefined or defined to be C<1> (and the platform supports it), then |
3817 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3886 | the respective watcher type is supported. If defined to be C<0>, then it |
3818 | code. |
3887 | is not. Disabling watcher types mainly saves codesize. |
3819 | |
3888 | |
3820 | =item EV_IDLE_ENABLE |
3889 | =item EV_FEATURES |
3821 | |
|
|
3822 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3823 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3824 | code. |
|
|
3825 | |
|
|
3826 | =item EV_EMBED_ENABLE |
|
|
3827 | |
|
|
3828 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3829 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3830 | watcher types, which therefore must not be disabled. |
|
|
3831 | |
|
|
3832 | =item EV_STAT_ENABLE |
|
|
3833 | |
|
|
3834 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3835 | defined to be C<0>, then they are not. |
|
|
3836 | |
|
|
3837 | =item EV_FORK_ENABLE |
|
|
3838 | |
|
|
3839 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3840 | defined to be C<0>, then they are not. |
|
|
3841 | |
|
|
3842 | =item EV_ASYNC_ENABLE |
|
|
3843 | |
|
|
3844 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3845 | defined to be C<0>, then they are not. |
|
|
3846 | |
|
|
3847 | =item EV_MINIMAL |
|
|
3848 | |
3890 | |
3849 | If you need to shave off some kilobytes of code at the expense of some |
3891 | If you need to shave off some kilobytes of code at the expense of some |
3850 | speed (but with the full API), define this symbol to C<1>. Currently this |
3892 | speed (but with the full API), you can define this symbol to request |
3851 | is used to override some inlining decisions, saves roughly 30% code size |
3893 | certain subsets of functionality. The default is to enable all features |
3852 | on amd64. It also selects a much smaller 2-heap for timer management over |
3894 | that can be enabled on the platform. |
3853 | the default 4-heap. |
|
|
3854 | |
3895 | |
3855 | You can save even more by disabling watcher types you do not need |
3896 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3856 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
3897 | with some broad features you want) and then selectively re-enable |
3857 | (C<-DNDEBUG>) will usually reduce code size a lot. |
3898 | additional parts you want, for example if you want everything minimal, |
|
|
3899 | but multiple event loop support, async and child watchers and the poll |
|
|
3900 | backend, use this: |
3858 | |
3901 | |
3859 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3902 | #define EV_FEATURES 0 |
3860 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3903 | #define EV_MULTIPLICITY 1 |
3861 | of the API are still available, and do not complain if this subset changes |
3904 | #define EV_USE_POLL 1 |
3862 | over time. |
3905 | #define EV_CHILD_ENABLE 1 |
|
|
3906 | #define EV_ASYNC_ENABLE 1 |
|
|
3907 | |
|
|
3908 | The actual value is a bitset, it can be a combination of the following |
|
|
3909 | values: |
|
|
3910 | |
|
|
3911 | =over 4 |
|
|
3912 | |
|
|
3913 | =item C<1> - faster/larger code |
|
|
3914 | |
|
|
3915 | Use larger code to speed up some operations. |
|
|
3916 | |
|
|
3917 | Currently this is used to override some inlining decisions (enlarging the roughly |
|
|
3918 | 30% code size on amd64. |
|
|
3919 | |
|
|
3920 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
3921 | gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
3922 | assertions. |
|
|
3923 | |
|
|
3924 | =item C<2> - faster/larger data structures |
|
|
3925 | |
|
|
3926 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
3927 | hash table sizes and so on. This will usually further increase codesize |
|
|
3928 | and can additionally have an effect on the size of data structures at |
|
|
3929 | runtime. |
|
|
3930 | |
|
|
3931 | =item C<4> - full API configuration |
|
|
3932 | |
|
|
3933 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
3934 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
3935 | |
|
|
3936 | =item C<8> - full API |
|
|
3937 | |
|
|
3938 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
3939 | details on which parts of the API are still available without this |
|
|
3940 | feature, and do not complain if this subset changes over time. |
|
|
3941 | |
|
|
3942 | =item C<16> - enable all optional watcher types |
|
|
3943 | |
|
|
3944 | Enables all optional watcher types. If you want to selectively enable |
|
|
3945 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
3946 | embed, async, child...) you can enable them manually by defining |
|
|
3947 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
3948 | |
|
|
3949 | =item C<32> - enable all backends |
|
|
3950 | |
|
|
3951 | This enables all backends - without this feature, you need to enable at |
|
|
3952 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
3953 | |
|
|
3954 | =item C<64> - enable OS-specific "helper" APIs |
|
|
3955 | |
|
|
3956 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
3957 | default. |
|
|
3958 | |
|
|
3959 | =back |
|
|
3960 | |
|
|
3961 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
3962 | reduces the compiled size of libev from 24.7Kb to 6.5Kb on my GNU/Linux |
|
|
3963 | amd64 system, while still giving you I/O watchers, timers and monotonic |
|
|
3964 | clock support. |
|
|
3965 | |
|
|
3966 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
3967 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
3968 | your program might be left out as well - a binary starting a timer and an |
|
|
3969 | I/O watcher then might come out at only 5Kb. |
|
|
3970 | |
|
|
3971 | =item EV_AVOID_STDIO |
|
|
3972 | |
|
|
3973 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
3974 | functions (printf, scanf, perror etc.). This will increase the codesize |
|
|
3975 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
3976 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
3977 | big. |
|
|
3978 | |
|
|
3979 | Note that error messages might become less precise when this option is |
|
|
3980 | enabled. |
3863 | |
3981 | |
3864 | =item EV_NSIG |
3982 | =item EV_NSIG |
3865 | |
3983 | |
3866 | The highest supported signal number, +1 (or, the number of |
3984 | The highest supported signal number, +1 (or, the number of |
3867 | signals): Normally, libev tries to deduce the maximum number of signals |
3985 | signals): Normally, libev tries to deduce the maximum number of signals |
… | |
… | |
3871 | statically allocates some 12-24 bytes per signal number. |
3989 | statically allocates some 12-24 bytes per signal number. |
3872 | |
3990 | |
3873 | =item EV_PID_HASHSIZE |
3991 | =item EV_PID_HASHSIZE |
3874 | |
3992 | |
3875 | C<ev_child> watchers use a small hash table to distribute workload by |
3993 | C<ev_child> watchers use a small hash table to distribute workload by |
3876 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3994 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3877 | than enough. If you need to manage thousands of children you might want to |
3995 | usually more than enough. If you need to manage thousands of children you |
3878 | increase this value (I<must> be a power of two). |
3996 | might want to increase this value (I<must> be a power of two). |
3879 | |
3997 | |
3880 | =item EV_INOTIFY_HASHSIZE |
3998 | =item EV_INOTIFY_HASHSIZE |
3881 | |
3999 | |
3882 | C<ev_stat> watchers use a small hash table to distribute workload by |
4000 | C<ev_stat> watchers use a small hash table to distribute workload by |
3883 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4001 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3884 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4002 | disabled), usually more than enough. If you need to manage thousands of |
3885 | watchers you might want to increase this value (I<must> be a power of |
4003 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3886 | two). |
4004 | power of two). |
3887 | |
4005 | |
3888 | =item EV_USE_4HEAP |
4006 | =item EV_USE_4HEAP |
3889 | |
4007 | |
3890 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4008 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3891 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4009 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3892 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4010 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3893 | faster performance with many (thousands) of watchers. |
4011 | faster performance with many (thousands) of watchers. |
3894 | |
4012 | |
3895 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4013 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3896 | (disabled). |
4014 | will be C<0>. |
3897 | |
4015 | |
3898 | =item EV_HEAP_CACHE_AT |
4016 | =item EV_HEAP_CACHE_AT |
3899 | |
4017 | |
3900 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4018 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3901 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4019 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3902 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4020 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3903 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4021 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3904 | but avoids random read accesses on heap changes. This improves performance |
4022 | but avoids random read accesses on heap changes. This improves performance |
3905 | noticeably with many (hundreds) of watchers. |
4023 | noticeably with many (hundreds) of watchers. |
3906 | |
4024 | |
3907 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4025 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3908 | (disabled). |
4026 | will be C<0>. |
3909 | |
4027 | |
3910 | =item EV_VERIFY |
4028 | =item EV_VERIFY |
3911 | |
4029 | |
3912 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4030 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
3913 | be done: If set to C<0>, no internal verification code will be compiled |
4031 | be done: If set to C<0>, no internal verification code will be compiled |
… | |
… | |
3915 | called. If set to C<2>, then the internal verification code will be |
4033 | called. If set to C<2>, then the internal verification code will be |
3916 | called once per loop, which can slow down libev. If set to C<3>, then the |
4034 | called once per loop, which can slow down libev. If set to C<3>, then the |
3917 | verification code will be called very frequently, which will slow down |
4035 | verification code will be called very frequently, which will slow down |
3918 | libev considerably. |
4036 | libev considerably. |
3919 | |
4037 | |
3920 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4038 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3921 | C<0>. |
4039 | will be C<0>. |
3922 | |
4040 | |
3923 | =item EV_COMMON |
4041 | =item EV_COMMON |
3924 | |
4042 | |
3925 | By default, all watchers have a C<void *data> member. By redefining |
4043 | By default, all watchers have a C<void *data> member. By redefining |
3926 | this macro to a something else you can include more and other types of |
4044 | this macro to a something else you can include more and other types of |
… | |
… | |
3984 | file. |
4102 | file. |
3985 | |
4103 | |
3986 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4104 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3987 | that everybody includes and which overrides some configure choices: |
4105 | that everybody includes and which overrides some configure choices: |
3988 | |
4106 | |
3989 | #define EV_MINIMAL 1 |
4107 | #define EV_FEATURES 8 |
3990 | #define EV_USE_POLL 0 |
4108 | #define EV_USE_SELECT 1 |
3991 | #define EV_MULTIPLICITY 0 |
|
|
3992 | #define EV_PERIODIC_ENABLE 0 |
4109 | #define EV_PREPARE_ENABLE 1 |
|
|
4110 | #define EV_IDLE_ENABLE 1 |
3993 | #define EV_STAT_ENABLE 0 |
4111 | #define EV_SIGNAL_ENABLE 1 |
3994 | #define EV_FORK_ENABLE 0 |
4112 | #define EV_CHILD_ENABLE 1 |
|
|
4113 | #define EV_USE_STDEXCEPT 0 |
3995 | #define EV_CONFIG_H <config.h> |
4114 | #define EV_CONFIG_H <config.h> |
3996 | #define EV_MINPRI 0 |
|
|
3997 | #define EV_MAXPRI 0 |
|
|
3998 | |
4115 | |
3999 | #include "ev++.h" |
4116 | #include "ev++.h" |
4000 | |
4117 | |
4001 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4118 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4002 | |
4119 | |