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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 |
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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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914 | =item ev_timer_again (loop) |
916 | =item ev_timer_again (loop) |
915 | |
917 | |
916 | This will act as if the timer timed out and restart it again if it is |
918 | This will act as if the timer timed out and restart it again if it is |
917 | repeating. The exact semantics are: |
919 | repeating. The exact semantics are: |
918 | |
920 | |
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921 | If the timer is pending, its pending status is cleared. |
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922 | |
919 | If the timer is started but nonrepeating, stop it. |
923 | If the timer is started but nonrepeating, stop it (as if it timed out). |
920 | |
924 | |
921 | If the timer is repeating, either start it if necessary (with the repeat |
925 | If the timer is repeating, either start it if necessary (with the |
922 | value), or reset the running timer to the repeat value. |
926 | C<repeat> value), or reset the running timer to the C<repeat> value. |
923 | |
927 | |
924 | This sounds a bit complicated, but here is a useful and typical |
928 | 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 |
929 | 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, |
930 | 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 |
931 | 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 |
932 | 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 |
933 | 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 |
934 | 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 |
935 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
932 | need be. |
936 | automatically restart it if need be. |
933 | |
937 | |
934 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
938 | That means you can ignore the C<after> value and C<ev_timer_start> |
935 | and only ever use the C<repeat> value: |
939 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
936 | |
940 | |
937 | ev_timer_init (timer, callback, 0., 5.); |
941 | ev_timer_init (timer, callback, 0., 5.); |
938 | ev_timer_again (loop, timer); |
942 | ev_timer_again (loop, timer); |
939 | ... |
943 | ... |
940 | timer->again = 17.; |
944 | timer->again = 17.; |
941 | ev_timer_again (loop, timer); |
945 | ev_timer_again (loop, timer); |
942 | ... |
946 | ... |
943 | timer->again = 10.; |
947 | timer->again = 10.; |
944 | ev_timer_again (loop, timer); |
948 | ev_timer_again (loop, timer); |
945 | |
949 | |
946 | This is more efficient then stopping/starting the timer eahc time you want |
950 | This is more slightly efficient then stopping/starting the timer each time |
947 | to modify its timeout value. |
951 | you want to modify its timeout value. |
948 | |
952 | |
949 | =item ev_tstamp repeat [read-write] |
953 | =item ev_tstamp repeat [read-write] |
950 | |
954 | |
951 | The current C<repeat> value. Will be used each time the watcher times out |
955 | 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), |
956 | or C<ev_timer_again> is called and determines the next timeout (if any), |
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1220 | The path does not need to exist: changing from "path exists" to "path does |
1224 | The path does not need to exist: changing from "path exists" to "path does |
1221 | not exist" is a status change like any other. The condition "path does |
1225 | 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 |
1226 | 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 |
1227 | otherwise always forced to be at least one) and all the other fields of |
1224 | the stat buffer having unspecified contents. |
1228 | the stat buffer having unspecified contents. |
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1229 | |
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1230 | The path I<should> be absolute and I<must not> end in a slash. If it is |
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1231 | relative and your working directory changes, the behaviour is undefined. |
1225 | |
1232 | |
1226 | Since there is no standard to do this, the portable implementation simply |
1233 | Since there is no standard to do this, the portable implementation simply |
1227 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1234 | 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 |
1235 | 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, |
1236 | a polling interval of C<0> (highly recommended!) then a I<suitable, |