… | |
… | |
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 |
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|
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 | |
… | |
… | |
1221 | not exist" is a status change like any other. The condition "path does |
1223 | 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 |
1224 | 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 |
1225 | otherwise always forced to be at least one) and all the other fields of |
1224 | the stat buffer having unspecified contents. |
1226 | the stat buffer having unspecified contents. |
1225 | |
1227 | |
|
|
1228 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1229 | relative and your working directory changes, the behaviour is undefined. |
|
|
1230 | |
1226 | Since there is no standard to do this, the portable implementation simply |
1231 | 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 |
1232 | 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 |
1233 | 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, |
1234 | 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 |
1235 | unspecified default> value will be used (which you can expect to be around |
1231 | five seconds, although this might change dynamically). Libev will also |
1236 | five seconds, although this might change dynamically). Libev will also |
1232 | impose a minimum interval which is currently around C<0.1>, but thats |
1237 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1234 | |
1239 | |
1235 | This watcher type is not meant for massive numbers of stat watchers, |
1240 | This watcher type is not meant for massive numbers of stat watchers, |
1236 | as even with OS-supported change notifications, this can be |
1241 | as even with OS-supported change notifications, this can be |
1237 | resource-intensive. |
1242 | resource-intensive. |
1238 | |
1243 | |
1239 | At the time of this writing, no specific OS backends are implemented, but |
1244 | 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. |
1245 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1246 | reader). Inotify will be used to give hints only and should not change the |
|
|
1247 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1248 | to fall back to regular polling again even with inotify, but changes are |
|
|
1249 | usually detected immediately, and if the file exists there will be no |
|
|
1250 | polling. |
1241 | |
1251 | |
1242 | =over 4 |
1252 | =over 4 |
1243 | |
1253 | |
1244 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1254 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1245 | |
1255 | |
… | |
… | |
2014 | |
2024 | |
2015 | =item EV_USE_DEVPOLL |
2025 | =item EV_USE_DEVPOLL |
2016 | |
2026 | |
2017 | reserved for future expansion, works like the USE symbols above. |
2027 | reserved for future expansion, works like the USE symbols above. |
2018 | |
2028 | |
|
|
2029 | =item EV_USE_INOTIFY |
|
|
2030 | |
|
|
2031 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2032 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2033 | be detected at runtime. |
|
|
2034 | |
2019 | =item EV_H |
2035 | =item EV_H |
2020 | |
2036 | |
2021 | The name of the F<ev.h> header file used to include it. The default if |
2037 | The name of the F<ev.h> header file used to include it. The default if |
2022 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2038 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2023 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2039 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
… | |
… | |
2078 | =item EV_PID_HASHSIZE |
2094 | =item EV_PID_HASHSIZE |
2079 | |
2095 | |
2080 | C<ev_child> watchers use a small hash table to distribute workload by |
2096 | C<ev_child> watchers use a small hash table to distribute workload by |
2081 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2097 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2082 | than enough. If you need to manage thousands of children you might want to |
2098 | than enough. If you need to manage thousands of children you might want to |
2083 | increase this value. |
2099 | increase this value (I<must> be a power of two). |
|
|
2100 | |
|
|
2101 | =item EV_INOTIFY_HASHSIZE |
|
|
2102 | |
|
|
2103 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2104 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2105 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2106 | watchers you might want to increase this value (I<must> be a power of |
|
|
2107 | two). |
2084 | |
2108 | |
2085 | =item EV_COMMON |
2109 | =item EV_COMMON |
2086 | |
2110 | |
2087 | By default, all watchers have a C<void *data> member. By redefining |
2111 | By default, all watchers have a C<void *data> member. By redefining |
2088 | this macro to a something else you can include more and other types of |
2112 | this macro to a something else you can include more and other types of |
… | |
… | |
2148 | |
2172 | |
2149 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2173 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2150 | |
2174 | |
2151 | =item Stopping check/prepare/idle watchers: O(1) |
2175 | =item Stopping check/prepare/idle watchers: O(1) |
2152 | |
2176 | |
2153 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
2177 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2154 | |
2178 | |
2155 | =item Finding the next timer per loop iteration: O(1) |
2179 | =item Finding the next timer per loop iteration: O(1) |
2156 | |
2180 | |
2157 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2181 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2158 | |
2182 | |