… | |
… | |
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 |
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|
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 | |
… | |
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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 | |
1226 | 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 |
1227 | 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 |
1228 | 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 |
1229 | 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, |
1230 | 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 |
1231 | five seconds, although this might change dynamically). Libev will also |
1233 | five seconds, although this might change dynamically). Libev will also |
1232 | 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 |
… | |
… | |
1234 | |
1236 | |
1235 | 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, |
1236 | as even with OS-supported change notifications, this can be |
1238 | as even with OS-supported change notifications, this can be |
1237 | resource-intensive. |
1239 | resource-intensive. |
1238 | |
1240 | |
1239 | 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 |
1240 | 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 |
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|
1247 | polling. |
1241 | |
1248 | |
1242 | =over 4 |
1249 | =over 4 |
1243 | |
1250 | |
1244 | =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) |
1245 | |
1252 | |