… | |
… | |
63 | details of the event, and then hand it over to libev by I<starting> the |
63 | details of the event, and then hand it over to libev by I<starting> the |
64 | watcher. |
64 | watcher. |
65 | |
65 | |
66 | =head1 FEATURES |
66 | =head1 FEATURES |
67 | |
67 | |
68 | Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the |
68 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
69 | bsd-specific C<kqueue> and the solaris-specific event port mechanisms |
69 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
70 | for file descriptor events (C<ev_io>), relative timers (C<ev_timer>), |
70 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
|
|
71 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
71 | absolute timers with customised rescheduling (C<ev_periodic>), synchronous |
72 | with customised rescheduling (C<ev_periodic>), synchronous signals |
72 | signals (C<ev_signal>), process status change events (C<ev_child>), and |
73 | (C<ev_signal>), process status change events (C<ev_child>), and event |
73 | event watchers dealing with the event loop mechanism itself (C<ev_idle>, |
74 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
74 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
75 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
75 | file watchers (C<ev_stat>) and even limited support for fork events |
76 | file watchers (C<ev_stat>) and even limited support for fork events |
76 | (C<ev_fork>). |
77 | (C<ev_fork>). |
77 | |
78 | |
78 | It also is quite fast (see this |
79 | It also is quite fast (see this |
… | |
… | |
162 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
163 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
163 | recommended ones. |
164 | recommended ones. |
164 | |
165 | |
165 | See the description of C<ev_embed> watchers for more info. |
166 | See the description of C<ev_embed> watchers for more info. |
166 | |
167 | |
167 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
168 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
168 | |
169 | |
169 | Sets the allocation function to use (the prototype and semantics are |
170 | Sets the allocation function to use (the prototype is similar - the |
170 | identical to the realloc C function). It is used to allocate and free |
171 | semantics is identical - to the realloc C function). It is used to |
171 | memory (no surprises here). If it returns zero when memory needs to be |
172 | allocate and free memory (no surprises here). If it returns zero when |
172 | allocated, the library might abort or take some potentially destructive |
173 | memory needs to be allocated, the library might abort or take some |
173 | action. The default is your system realloc function. |
174 | potentially destructive action. The default is your system realloc |
|
|
175 | function. |
174 | |
176 | |
175 | You could override this function in high-availability programs to, say, |
177 | You could override this function in high-availability programs to, say, |
176 | free some memory if it cannot allocate memory, to use a special allocator, |
178 | free some memory if it cannot allocate memory, to use a special allocator, |
177 | or even to sleep a while and retry until some memory is available. |
179 | or even to sleep a while and retry until some memory is available. |
178 | |
180 | |
… | |
… | |
264 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
266 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
265 | override the flags completely if it is found in the environment. This is |
267 | override the flags completely if it is found in the environment. This is |
266 | useful to try out specific backends to test their performance, or to work |
268 | useful to try out specific backends to test their performance, or to work |
267 | around bugs. |
269 | around bugs. |
268 | |
270 | |
|
|
271 | =item C<EVFLAG_FORKCHECK> |
|
|
272 | |
|
|
273 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
274 | a fork, you can also make libev check for a fork in each iteration by |
|
|
275 | enabling this flag. |
|
|
276 | |
|
|
277 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
278 | and thus this might slow down your event loop if you do a lot of loop |
|
|
279 | iterations and little real work, but is usually not noticeable (on my |
|
|
280 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
281 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
282 | C<pthread_atfork> which is even faster). |
|
|
283 | |
|
|
284 | The big advantage of this flag is that you can forget about fork (and |
|
|
285 | forget about forgetting to tell libev about forking) when you use this |
|
|
286 | flag. |
|
|
287 | |
|
|
288 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
289 | environment variable. |
|
|
290 | |
269 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
291 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
270 | |
292 | |
271 | This is your standard select(2) backend. Not I<completely> standard, as |
293 | This is your standard select(2) backend. Not I<completely> standard, as |
272 | libev tries to roll its own fd_set with no limits on the number of fds, |
294 | libev tries to roll its own fd_set with no limits on the number of fds, |
273 | but if that fails, expect a fairly low limit on the number of fds when |
295 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
407 | =item ev_loop_fork (loop) |
429 | =item ev_loop_fork (loop) |
408 | |
430 | |
409 | Like C<ev_default_fork>, but acts on an event loop created by |
431 | Like C<ev_default_fork>, but acts on an event loop created by |
410 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
432 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
411 | after fork, and how you do this is entirely your own problem. |
433 | after fork, and how you do this is entirely your own problem. |
|
|
434 | |
|
|
435 | =item unsigned int ev_loop_count (loop) |
|
|
436 | |
|
|
437 | Returns the count of loop iterations for the loop, which is identical to |
|
|
438 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
439 | happily wraps around with enough iterations. |
|
|
440 | |
|
|
441 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
442 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
443 | C<ev_prepare> and C<ev_check> calls. |
412 | |
444 | |
413 | =item unsigned int ev_backend (loop) |
445 | =item unsigned int ev_backend (loop) |
414 | |
446 | |
415 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
447 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
416 | use. |
448 | use. |
… | |
… | |
914 | =item ev_timer_again (loop) |
946 | =item ev_timer_again (loop) |
915 | |
947 | |
916 | This will act as if the timer timed out and restart it again if it is |
948 | This will act as if the timer timed out and restart it again if it is |
917 | repeating. The exact semantics are: |
949 | repeating. The exact semantics are: |
918 | |
950 | |
|
|
951 | If the timer is pending, its pending status is cleared. |
|
|
952 | |
919 | If the timer is started but nonrepeating, stop it. |
953 | If the timer is started but nonrepeating, stop it (as if it timed out). |
920 | |
954 | |
921 | If the timer is repeating, either start it if necessary (with the repeat |
955 | If the timer is repeating, either start it if necessary (with the |
922 | value), or reset the running timer to the repeat value. |
956 | C<repeat> value), or reset the running timer to the C<repeat> value. |
923 | |
957 | |
924 | This sounds a bit complicated, but here is a useful and typical |
958 | This sounds a bit complicated, but here is a useful and typical |
925 | example: Imagine you have a tcp connection and you want a so-called |
959 | example: Imagine you have a tcp connection and you want a so-called idle |
926 | idle timeout, that is, you want to be called when there have been, |
960 | timeout, that is, you want to be called when there have been, say, 60 |
927 | say, 60 seconds of inactivity on the socket. The easiest way to do |
961 | seconds of inactivity on the socket. The easiest way to do this is to |
928 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
962 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
929 | C<ev_timer_again> each time you successfully read or write some data. If |
963 | C<ev_timer_again> each time you successfully read or write some data. If |
930 | you go into an idle state where you do not expect data to travel on the |
964 | you go into an idle state where you do not expect data to travel on the |
931 | socket, you can stop the timer, and again will automatically restart it if |
965 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
932 | need be. |
966 | automatically restart it if need be. |
933 | |
967 | |
934 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
968 | That means you can ignore the C<after> value and C<ev_timer_start> |
935 | and only ever use the C<repeat> value: |
969 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
936 | |
970 | |
937 | ev_timer_init (timer, callback, 0., 5.); |
971 | ev_timer_init (timer, callback, 0., 5.); |
938 | ev_timer_again (loop, timer); |
972 | ev_timer_again (loop, timer); |
939 | ... |
973 | ... |
940 | timer->again = 17.; |
974 | timer->again = 17.; |
941 | ev_timer_again (loop, timer); |
975 | ev_timer_again (loop, timer); |
942 | ... |
976 | ... |
943 | timer->again = 10.; |
977 | timer->again = 10.; |
944 | ev_timer_again (loop, timer); |
978 | ev_timer_again (loop, timer); |
945 | |
979 | |
946 | This is more efficient then stopping/starting the timer eahc time you want |
980 | This is more slightly efficient then stopping/starting the timer each time |
947 | to modify its timeout value. |
981 | you want to modify its timeout value. |
948 | |
982 | |
949 | =item ev_tstamp repeat [read-write] |
983 | =item ev_tstamp repeat [read-write] |
950 | |
984 | |
951 | The current C<repeat> value. Will be used each time the watcher times out |
985 | The current C<repeat> value. Will be used each time the watcher times out |
952 | or C<ev_timer_again> is called and determines the next timeout (if any), |
986 | or C<ev_timer_again> is called and determines the next timeout (if any), |
… | |
… | |
1221 | not exist" is a status change like any other. The condition "path does |
1255 | not exist" is a status change like any other. The condition "path does |
1222 | not exist" is signified by the C<st_nlink> field being zero (which is |
1256 | not exist" is signified by the C<st_nlink> field being zero (which is |
1223 | otherwise always forced to be at least one) and all the other fields of |
1257 | otherwise always forced to be at least one) and all the other fields of |
1224 | the stat buffer having unspecified contents. |
1258 | the stat buffer having unspecified contents. |
1225 | |
1259 | |
|
|
1260 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1261 | relative and your working directory changes, the behaviour is undefined. |
|
|
1262 | |
1226 | Since there is no standard to do this, the portable implementation simply |
1263 | Since there is no standard to do this, the portable implementation simply |
1227 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
1264 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1228 | can specify a recommended polling interval for this case. If you specify |
1265 | can specify a recommended polling interval for this case. If you specify |
1229 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1266 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1230 | unspecified default> value will be used (which you can expect to be around |
1267 | unspecified default> value will be used (which you can expect to be around |
1231 | five seconds, although this might change dynamically). Libev will also |
1268 | five seconds, although this might change dynamically). Libev will also |
1232 | impose a minimum interval which is currently around C<0.1>, but thats |
1269 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1234 | |
1271 | |
1235 | This watcher type is not meant for massive numbers of stat watchers, |
1272 | This watcher type is not meant for massive numbers of stat watchers, |
1236 | as even with OS-supported change notifications, this can be |
1273 | as even with OS-supported change notifications, this can be |
1237 | resource-intensive. |
1274 | resource-intensive. |
1238 | |
1275 | |
1239 | At the time of this writing, no specific OS backends are implemented, but |
1276 | At the time of this writing, only the Linux inotify interface is |
1240 | if demand increases, at least a kqueue and inotify backend will be added. |
1277 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1278 | reader). Inotify will be used to give hints only and should not change the |
|
|
1279 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1280 | to fall back to regular polling again even with inotify, but changes are |
|
|
1281 | usually detected immediately, and if the file exists there will be no |
|
|
1282 | polling. |
1241 | |
1283 | |
1242 | =over 4 |
1284 | =over 4 |
1243 | |
1285 | |
1244 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1286 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1245 | |
1287 | |
… | |
… | |
1425 | |
1467 | |
1426 | // create io watchers for each fd and a timer before blocking |
1468 | // create io watchers for each fd and a timer before blocking |
1427 | static void |
1469 | static void |
1428 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1470 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1429 | { |
1471 | { |
1430 | int timeout = 3600000;truct pollfd fds [nfd]; |
1472 | int timeout = 3600000; |
|
|
1473 | struct pollfd fds [nfd]; |
1431 | // actual code will need to loop here and realloc etc. |
1474 | // actual code will need to loop here and realloc etc. |
1432 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1475 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1433 | |
1476 | |
1434 | /* the callback is illegal, but won't be called as we stop during check */ |
1477 | /* the callback is illegal, but won't be called as we stop during check */ |
1435 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1478 | ev_timer_init (&tw, 0, timeout * 1e-3); |
… | |
… | |
1816 | Similar to the other two macros, this gives you the value of the default |
1859 | Similar to the other two macros, this gives you the value of the default |
1817 | loop, if multiple loops are supported ("ev loop default"). |
1860 | loop, if multiple loops are supported ("ev loop default"). |
1818 | |
1861 | |
1819 | =back |
1862 | =back |
1820 | |
1863 | |
1821 | Example: Declare and initialise a check watcher, working regardless of |
1864 | Example: Declare and initialise a check watcher, utilising the above |
1822 | wether multiple loops are supported or not. |
1865 | macros so it will work regardless of wether multiple loops are supported |
|
|
1866 | or not. |
1823 | |
1867 | |
1824 | static void |
1868 | static void |
1825 | check_cb (EV_P_ ev_timer *w, int revents) |
1869 | check_cb (EV_P_ ev_timer *w, int revents) |
1826 | { |
1870 | { |
1827 | ev_check_stop (EV_A_ w); |
1871 | ev_check_stop (EV_A_ w); |
… | |
… | |
1829 | |
1873 | |
1830 | ev_check check; |
1874 | ev_check check; |
1831 | ev_check_init (&check, check_cb); |
1875 | ev_check_init (&check, check_cb); |
1832 | ev_check_start (EV_DEFAULT_ &check); |
1876 | ev_check_start (EV_DEFAULT_ &check); |
1833 | ev_loop (EV_DEFAULT_ 0); |
1877 | ev_loop (EV_DEFAULT_ 0); |
1834 | |
|
|
1835 | |
1878 | |
1836 | =head1 EMBEDDING |
1879 | =head1 EMBEDDING |
1837 | |
1880 | |
1838 | Libev can (and often is) directly embedded into host |
1881 | Libev can (and often is) directly embedded into host |
1839 | applications. Examples of applications that embed it include the Deliantra |
1882 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
1879 | ev_vars.h |
1922 | ev_vars.h |
1880 | ev_wrap.h |
1923 | ev_wrap.h |
1881 | |
1924 | |
1882 | ev_win32.c required on win32 platforms only |
1925 | ev_win32.c required on win32 platforms only |
1883 | |
1926 | |
1884 | ev_select.c only when select backend is enabled (which is by default) |
1927 | ev_select.c only when select backend is enabled (which is enabled by default) |
1885 | ev_poll.c only when poll backend is enabled (disabled by default) |
1928 | ev_poll.c only when poll backend is enabled (disabled by default) |
1886 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1929 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1887 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1930 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1888 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1931 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1889 | |
1932 | |
… | |
… | |
2131 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2174 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2132 | will be compiled. It is pretty complex because it provides its own header |
2175 | will be compiled. It is pretty complex because it provides its own header |
2133 | file. |
2176 | file. |
2134 | |
2177 | |
2135 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2178 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2136 | that everybody includes and which overrides some autoconf choices: |
2179 | that everybody includes and which overrides some configure choices: |
2137 | |
2180 | |
|
|
2181 | #define EV_MINIMAL 1 |
2138 | #define EV_USE_POLL 0 |
2182 | #define EV_USE_POLL 0 |
2139 | #define EV_MULTIPLICITY 0 |
2183 | #define EV_MULTIPLICITY 0 |
2140 | #define EV_PERIODICS 0 |
2184 | #define EV_PERIODIC_ENABLE 0 |
|
|
2185 | #define EV_STAT_ENABLE 0 |
|
|
2186 | #define EV_FORK_ENABLE 0 |
2141 | #define EV_CONFIG_H <config.h> |
2187 | #define EV_CONFIG_H <config.h> |
|
|
2188 | #define EV_MINPRI 0 |
|
|
2189 | #define EV_MAXPRI 0 |
2142 | |
2190 | |
2143 | #include "ev++.h" |
2191 | #include "ev++.h" |
2144 | |
2192 | |
2145 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2193 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2146 | |
2194 | |