… | |
… | |
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 | |
… | |
… | |
703 | events but its callback has not yet been invoked). As long as a watcher |
705 | events but its callback has not yet been invoked). As long as a watcher |
704 | is pending (but not active) you must not call an init function on it (but |
706 | is pending (but not active) you must not call an init function on it (but |
705 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
707 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
706 | libev (e.g. you cnanot C<free ()> it). |
708 | libev (e.g. you cnanot C<free ()> it). |
707 | |
709 | |
708 | =item callback = ev_cb (ev_TYPE *watcher) |
710 | =item callback ev_cb (ev_TYPE *watcher) |
709 | |
711 | |
710 | Returns the callback currently set on the watcher. |
712 | Returns the callback currently set on the watcher. |
711 | |
713 | |
712 | =item ev_cb_set (ev_TYPE *watcher, callback) |
714 | =item ev_cb_set (ev_TYPE *watcher, callback) |
713 | |
715 | |
… | |
… | |
741 | { |
743 | { |
742 | struct my_io *w = (struct my_io *)w_; |
744 | struct my_io *w = (struct my_io *)w_; |
743 | ... |
745 | ... |
744 | } |
746 | } |
745 | |
747 | |
746 | More interesting and less C-conformant ways of catsing your callback type |
748 | More interesting and less C-conformant ways of casting your callback type |
747 | have been omitted.... |
749 | instead have been omitted. |
|
|
750 | |
|
|
751 | Another common scenario is having some data structure with multiple |
|
|
752 | watchers: |
|
|
753 | |
|
|
754 | struct my_biggy |
|
|
755 | { |
|
|
756 | int some_data; |
|
|
757 | ev_timer t1; |
|
|
758 | ev_timer t2; |
|
|
759 | } |
|
|
760 | |
|
|
761 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
762 | you need to use C<offsetof>: |
|
|
763 | |
|
|
764 | #include <stddef.h> |
|
|
765 | |
|
|
766 | static void |
|
|
767 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
768 | { |
|
|
769 | struct my_biggy big = (struct my_biggy * |
|
|
770 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
771 | } |
|
|
772 | |
|
|
773 | static void |
|
|
774 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
775 | { |
|
|
776 | struct my_biggy big = (struct my_biggy * |
|
|
777 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
778 | } |
748 | |
779 | |
749 | |
780 | |
750 | =head1 WATCHER TYPES |
781 | =head1 WATCHER TYPES |
751 | |
782 | |
752 | This section describes each watcher in detail, but will not repeat |
783 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1193 | not exist" is signified by the C<st_nlink> field being zero (which is |
1224 | not exist" is signified by the C<st_nlink> field being zero (which is |
1194 | otherwise always forced to be at least one) and all the other fields of |
1225 | otherwise always forced to be at least one) and all the other fields of |
1195 | the stat buffer having unspecified contents. |
1226 | the stat buffer having unspecified contents. |
1196 | |
1227 | |
1197 | Since there is no standard to do this, the portable implementation simply |
1228 | Since there is no standard to do this, the portable implementation simply |
1198 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
1229 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1199 | can specify a recommended polling interval for this case. If you specify |
1230 | can specify a recommended polling interval for this case. If you specify |
1200 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1231 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1201 | unspecified default> value will be used (which you can expect to be around |
1232 | unspecified default> value will be used (which you can expect to be around |
1202 | five seconds, although this might change dynamically). Libev will also |
1233 | five seconds, although this might change dynamically). Libev will also |
1203 | impose a minimum interval which is currently around C<0.1>, but thats |
1234 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1205 | |
1236 | |
1206 | This watcher type is not meant for massive numbers of stat watchers, |
1237 | This watcher type is not meant for massive numbers of stat watchers, |
1207 | as even with OS-supported change notifications, this can be |
1238 | as even with OS-supported change notifications, this can be |
1208 | resource-intensive. |
1239 | resource-intensive. |
1209 | |
1240 | |
1210 | At the time of this writing, no specific OS backends are implemented, but |
1241 | At the time of this writing, only the Linux inotify interface is |
1211 | if demand increases, at least a kqueue and inotify backend will be added. |
1242 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1243 | reader). Inotify will be used to give hints only and should not change the |
|
|
1244 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1245 | to fall back to regular polling again even with inotify, but changes are |
|
|
1246 | usually detected immediately, and if the file exists there will be no |
|
|
1247 | polling. |
1212 | |
1248 | |
1213 | =over 4 |
1249 | =over 4 |
1214 | |
1250 | |
1215 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1251 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1216 | |
1252 | |
… | |
… | |
1985 | |
2021 | |
1986 | =item EV_USE_DEVPOLL |
2022 | =item EV_USE_DEVPOLL |
1987 | |
2023 | |
1988 | reserved for future expansion, works like the USE symbols above. |
2024 | reserved for future expansion, works like the USE symbols above. |
1989 | |
2025 | |
|
|
2026 | =item EV_USE_INOTIFY |
|
|
2027 | |
|
|
2028 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2029 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2030 | be detected at runtime. |
|
|
2031 | |
1990 | =item EV_H |
2032 | =item EV_H |
1991 | |
2033 | |
1992 | The name of the F<ev.h> header file used to include it. The default if |
2034 | The name of the F<ev.h> header file used to include it. The default if |
1993 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2035 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
1994 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2036 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
… | |
… | |
2049 | =item EV_PID_HASHSIZE |
2091 | =item EV_PID_HASHSIZE |
2050 | |
2092 | |
2051 | C<ev_child> watchers use a small hash table to distribute workload by |
2093 | C<ev_child> watchers use a small hash table to distribute workload by |
2052 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2094 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2053 | than enough. If you need to manage thousands of children you might want to |
2095 | than enough. If you need to manage thousands of children you might want to |
2054 | increase this value. |
2096 | increase this value (I<must> be a power of two). |
|
|
2097 | |
|
|
2098 | =item EV_INOTIFY_HASHSIZE |
|
|
2099 | |
|
|
2100 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2101 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2102 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2103 | watchers you might want to increase this value (I<must> be a power of |
|
|
2104 | two). |
2055 | |
2105 | |
2056 | =item EV_COMMON |
2106 | =item EV_COMMON |
2057 | |
2107 | |
2058 | By default, all watchers have a C<void *data> member. By redefining |
2108 | By default, all watchers have a C<void *data> member. By redefining |
2059 | this macro to a something else you can include more and other types of |
2109 | this macro to a something else you can include more and other types of |
… | |
… | |
2119 | |
2169 | |
2120 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2170 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2121 | |
2171 | |
2122 | =item Stopping check/prepare/idle watchers: O(1) |
2172 | =item Stopping check/prepare/idle watchers: O(1) |
2123 | |
2173 | |
2124 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
2174 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2125 | |
2175 | |
2126 | =item Finding the next timer per loop iteration: O(1) |
2176 | =item Finding the next timer per loop iteration: O(1) |
2127 | |
2177 | |
2128 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2178 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2129 | |
2179 | |