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Revision 1.28 by root, Tue Nov 27 20:26:50 2007 UTC vs.
Revision 1.32 by root, Wed Nov 28 17:32:24 2007 UTC

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127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-11-28" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
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210watchers\fR, which are relatively small C structures you initialise with the 210watchers\fR, which are relatively small C structures you initialise with the
211details of the event, and then hand it over to libev by \fIstarting\fR the 211details of the event, and then hand it over to libev by \fIstarting\fR the
212watcher. 212watcher.
213.SH "FEATURES" 213.SH "FEATURES"
214.IX Header "FEATURES" 214.IX Header "FEATURES"
215Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the linux-specific \f(CW\*(C`epoll\*(C'\fR, the 215Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
216bsd-specific \f(CW\*(C`kqueue\*(C'\fR and the solaris-specific event port mechanisms 216BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
217for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), 217for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
218(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
218absolute timers with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous 219with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
219signals (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and 220(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
220event watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, 221watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
221\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as 222\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as
222file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events 223file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
223(\f(CW\*(C`ev_fork\*(C'\fR). 224(\f(CW\*(C`ev_fork\*(C'\fR).
224.PP 225.PP
225It also is quite fast (see this 226It also is quite fast (see this
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304might be supported on the current system, you would need to look at 305might be supported on the current system, you would need to look at
305\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for 306\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
306recommended ones. 307recommended ones.
307.Sp 308.Sp
308See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 309See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
309.IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4 310.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
310.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 311.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
311Sets the allocation function to use (the prototype and semantics are 312Sets the allocation function to use (the prototype is similar \- the
312identical to the realloc C function). It is used to allocate and free 313semantics is identical \- to the realloc C function). It is used to
313memory (no surprises here). If it returns zero when memory needs to be 314allocate and free memory (no surprises here). If it returns zero when
314allocated, the library might abort or take some potentially destructive 315memory needs to be allocated, the library might abort or take some
315action. The default is your system realloc function. 316potentially destructive action. The default is your system realloc
317function.
316.Sp 318.Sp
317You could override this function in high-availability programs to, say, 319You could override this function in high-availability programs to, say,
318free some memory if it cannot allocate memory, to use a special allocator, 320free some memory if it cannot allocate memory, to use a special allocator,
319or even to sleep a while and retry until some memory is available. 321or even to sleep a while and retry until some memory is available.
320.Sp 322.Sp
… …
856Returns a true value iff the watcher is pending, (i.e. it has outstanding 858Returns a true value iff the watcher is pending, (i.e. it has outstanding
857events but its callback has not yet been invoked). As long as a watcher 859events but its callback has not yet been invoked). As long as a watcher
858is pending (but not active) you must not call an init function on it (but 860is pending (but not active) you must not call an init function on it (but
859\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 861\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
860libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 862libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
861.IP "callback = ev_cb (ev_TYPE *watcher)" 4 863.IP "callback ev_cb (ev_TYPE *watcher)" 4
862.IX Item "callback = ev_cb (ev_TYPE *watcher)" 864.IX Item "callback ev_cb (ev_TYPE *watcher)"
863Returns the callback currently set on the watcher. 865Returns the callback currently set on the watcher.
864.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 866.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
865.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 867.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
866Change the callback. You can change the callback at virtually any time 868Change the callback. You can change the callback at virtually any time
867(modulo threads). 869(modulo threads).
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893\& struct my_io *w = (struct my_io *)w_; 895\& struct my_io *w = (struct my_io *)w_;
894\& ... 896\& ...
895\& } 897\& }
896.Ve 898.Ve
897.PP 899.PP
898More interesting and less C\-conformant ways of catsing your callback type 900More interesting and less C\-conformant ways of casting your callback type
899have been omitted.... 901instead have been omitted.
902.PP
903Another common scenario is having some data structure with multiple
904watchers:
905.PP
906.Vb 6
907\& struct my_biggy
908\& {
909\& int some_data;
910\& ev_timer t1;
911\& ev_timer t2;
912\& }
913.Ve
914.PP
915In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
916you need to use \f(CW\*(C`offsetof\*(C'\fR:
917.PP
918.Vb 1
919\& #include <stddef.h>
920.Ve
921.PP
922.Vb 6
923\& static void
924\& t1_cb (EV_P_ struct ev_timer *w, int revents)
925\& {
926\& struct my_biggy big = (struct my_biggy *
927\& (((char *)w) - offsetof (struct my_biggy, t1));
928\& }
929.Ve
930.PP
931.Vb 6
932\& static void
933\& t2_cb (EV_P_ struct ev_timer *w, int revents)
934\& {
935\& struct my_biggy big = (struct my_biggy *
936\& (((char *)w) - offsetof (struct my_biggy, t2));
937\& }
938.Ve
900.SH "WATCHER TYPES" 939.SH "WATCHER TYPES"
901.IX Header "WATCHER TYPES" 940.IX Header "WATCHER TYPES"
902This section describes each watcher in detail, but will not repeat 941This section describes each watcher in detail, but will not repeat
903information given in the last section. Any initialisation/set macros, 942information given in the last section. Any initialisation/set macros,
904functions and members specific to the watcher type are explained. 943functions and members specific to the watcher type are explained.
… …
1346not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is 1385not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1347otherwise always forced to be at least one) and all the other fields of 1386otherwise always forced to be at least one) and all the other fields of
1348the stat buffer having unspecified contents. 1387the stat buffer having unspecified contents.
1349.PP 1388.PP
1350Since there is no standard to do this, the portable implementation simply 1389Since there is no standard to do this, the portable implementation simply
1351calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You 1390calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1352can specify a recommended polling interval for this case. If you specify 1391can specify a recommended polling interval for this case. If you specify
1353a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1392a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1354unspecified default\fR value will be used (which you can expect to be around 1393unspecified default\fR value will be used (which you can expect to be around
1355five seconds, although this might change dynamically). Libev will also 1394five seconds, although this might change dynamically). Libev will also
1356impose a minimum interval which is currently around \f(CW0.1\fR, but thats 1395impose a minimum interval which is currently around \f(CW0.1\fR, but thats
… …
1358.PP 1397.PP
1359This watcher type is not meant for massive numbers of stat watchers, 1398This watcher type is not meant for massive numbers of stat watchers,
1360as even with OS-supported change notifications, this can be 1399as even with OS-supported change notifications, this can be
1361resource\-intensive. 1400resource\-intensive.
1362.PP 1401.PP
1363At the time of this writing, no specific \s-1OS\s0 backends are implemented, but 1402At the time of this writing, only the Linux inotify interface is
1364if demand increases, at least a kqueue and inotify backend will be added. 1403implemented (implementing kqueue support is left as an exercise for the
1404reader). Inotify will be used to give hints only and should not change the
1405semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1406to fall back to regular polling again even with inotify, but changes are
1407usually detected immediately, and if the file exists there will be no
1408polling.
1365.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1409.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1366.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1410.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1367.PD 0 1411.PD 0
1368.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1412.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1369.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1413.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
2133otherwise another method will be used as fallback. This is the preferred 2177otherwise another method will be used as fallback. This is the preferred
2134backend for Solaris 10 systems. 2178backend for Solaris 10 systems.
2135.IP "\s-1EV_USE_DEVPOLL\s0" 4 2179.IP "\s-1EV_USE_DEVPOLL\s0" 4
2136.IX Item "EV_USE_DEVPOLL" 2180.IX Item "EV_USE_DEVPOLL"
2137reserved for future expansion, works like the \s-1USE\s0 symbols above. 2181reserved for future expansion, works like the \s-1USE\s0 symbols above.
2182.IP "\s-1EV_USE_INOTIFY\s0" 4
2183.IX Item "EV_USE_INOTIFY"
2184If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2185interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2186be detected at runtime.
2138.IP "\s-1EV_H\s0" 4 2187.IP "\s-1EV_H\s0" 4
2139.IX Item "EV_H" 2188.IX Item "EV_H"
2140The name of the \fIev.h\fR header file used to include it. The default if 2189The name of the \fIev.h\fR header file used to include it. The default if
2141undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This 2190undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2142can be used to virtually rename the \fIev.h\fR header file in case of conflicts. 2191can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
… …
2187.IP "\s-1EV_PID_HASHSIZE\s0" 4 2236.IP "\s-1EV_PID_HASHSIZE\s0" 4
2188.IX Item "EV_PID_HASHSIZE" 2237.IX Item "EV_PID_HASHSIZE"
2189\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 2238\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2190pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more 2239pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2191than enough. If you need to manage thousands of children you might want to 2240than enough. If you need to manage thousands of children you might want to
2192increase this value. 2241increase this value (\fImust\fR be a power of two).
2242.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2243.IX Item "EV_INOTIFY_HASHSIZE"
2244\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2245inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2246usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2247watchers you might want to increase this value (\fImust\fR be a power of
2248two).
2193.IP "\s-1EV_COMMON\s0" 4 2249.IP "\s-1EV_COMMON\s0" 4
2194.IX Item "EV_COMMON" 2250.IX Item "EV_COMMON"
2195By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2251By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2196this macro to a something else you can include more and other types of 2252this macro to a something else you can include more and other types of
2197members. You have to define it each time you include one of the files, 2253members. You have to define it each time you include one of the files,
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2261.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2317.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2262.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2318.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2263.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2319.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2264.IP "Stopping check/prepare/idle watchers: O(1)" 4 2320.IP "Stopping check/prepare/idle watchers: O(1)" 4
2265.IX Item "Stopping check/prepare/idle watchers: O(1)" 2321.IX Item "Stopping check/prepare/idle watchers: O(1)"
2266.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 2322.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2267.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 2323.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2268.IP "Finding the next timer per loop iteration: O(1)" 4 2324.IP "Finding the next timer per loop iteration: O(1)" 4
2269.IX Item "Finding the next timer per loop iteration: O(1)" 2325.IX Item "Finding the next timer per loop iteration: O(1)"
2270.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2326.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2271.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2327.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2272.IP "Activating one watcher: O(1)" 4 2328.IP "Activating one watcher: O(1)" 4

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