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4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
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9 | <meta name="created" content="Wed Nov 28 12:27:27 2007" /> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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133 | watcher.</p> |
133 | watcher.</p> |
134 | |
134 | |
135 | </div> |
135 | </div> |
136 | <h1 id="FEATURES">FEATURES</h1> |
136 | <h1 id="FEATURES">FEATURES</h1> |
137 | <div id="FEATURES_CONTENT"> |
137 | <div id="FEATURES_CONTENT"> |
138 | <p>Libev supports <code>select</code>, <code>poll</code>, the linux-specific <code>epoll</code>, the |
138 | <p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the |
139 | bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms |
139 | BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms |
140 | for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>), |
140 | for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface |
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141 | (for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers |
141 | absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous |
142 | with customised rescheduling (<code>ev_periodic</code>), synchronous signals |
142 | signals (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and |
143 | (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event |
143 | event watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
144 | watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
144 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
145 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
145 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
146 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
146 | (<code>ev_fork</code>).</p> |
147 | (<code>ev_fork</code>).</p> |
147 | <p>It also is quite fast (see this |
148 | <p>It also is quite fast (see this |
148 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
149 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
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229 | might be supported on the current system, you would need to look at |
230 | might be supported on the current system, you would need to look at |
230 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
231 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
231 | recommended ones.</p> |
232 | recommended ones.</p> |
232 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
233 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
233 | </dd> |
234 | </dd> |
234 | <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt> |
235 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
235 | <dd> |
236 | <dd> |
236 | <p>Sets the allocation function to use (the prototype and semantics are |
237 | <p>Sets the allocation function to use (the prototype is similar - the |
237 | identical to the realloc C function). It is used to allocate and free |
238 | semantics is identical - to the realloc C function). It is used to |
238 | memory (no surprises here). If it returns zero when memory needs to be |
239 | allocate and free memory (no surprises here). If it returns zero when |
239 | allocated, the library might abort or take some potentially destructive |
240 | memory needs to be allocated, the library might abort or take some |
240 | action. The default is your system realloc function.</p> |
241 | potentially destructive action. The default is your system realloc |
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242 | function.</p> |
241 | <p>You could override this function in high-availability programs to, say, |
243 | <p>You could override this function in high-availability programs to, say, |
242 | free some memory if it cannot allocate memory, to use a special allocator, |
244 | free some memory if it cannot allocate memory, to use a special allocator, |
243 | or even to sleep a while and retry until some memory is available.</p> |
245 | or even to sleep a while and retry until some memory is available.</p> |
244 | <p>Example: Replace the libev allocator with one that waits a bit and then |
246 | <p>Example: Replace the libev allocator with one that waits a bit and then |
245 | retries).</p> |
247 | retries).</p> |
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323 | or setgid) then libev will <i>not</i> look at the environment variable |
325 | or setgid) then libev will <i>not</i> look at the environment variable |
324 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
326 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
325 | override the flags completely if it is found in the environment. This is |
327 | override the flags completely if it is found in the environment. This is |
326 | useful to try out specific backends to test their performance, or to work |
328 | useful to try out specific backends to test their performance, or to work |
327 | around bugs.</p> |
329 | around bugs.</p> |
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330 | </dd> |
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331 | <dt><code>EVFLAG_FORKCHECK</code></dt> |
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332 | <dd> |
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333 | <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after |
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334 | a fork, you can also make libev check for a fork in each iteration by |
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335 | enabling this flag.</p> |
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336 | <p>This works by calling <code>getpid ()</code> on every iteration of the loop, |
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337 | and thus this might slow down your event loop if you do a lot of loop |
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338 | iterations and little real work, but is usually not noticable (on my |
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339 | Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence |
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340 | without a syscall and thus <i>very</i> fast, but my Linux system also has |
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341 | <code>pthread_atfork</code> which is even faster).</p> |
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342 | <p>The big advantage of this flag is that you can forget about fork (and |
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343 | forget about forgetting to tell libev about forking) when you use this |
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344 | flag.</p> |
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345 | <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code> |
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346 | environment variable.</p> |
328 | </dd> |
347 | </dd> |
329 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
348 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
330 | <dd> |
349 | <dd> |
331 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
350 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
332 | libev tries to roll its own fd_set with no limits on the number of fds, |
351 | libev tries to roll its own fd_set with no limits on the number of fds, |
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950 | </dd> |
969 | </dd> |
951 | <dt>ev_timer_again (loop)</dt> |
970 | <dt>ev_timer_again (loop)</dt> |
952 | <dd> |
971 | <dd> |
953 | <p>This will act as if the timer timed out and restart it again if it is |
972 | <p>This will act as if the timer timed out and restart it again if it is |
954 | repeating. The exact semantics are:</p> |
973 | repeating. The exact semantics are:</p> |
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974 | <p>If the timer is pending, its pending status is cleared.</p> |
955 | <p>If the timer is started but nonrepeating, stop it.</p> |
975 | <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p> |
956 | <p>If the timer is repeating, either start it if necessary (with the repeat |
976 | <p>If the timer is repeating, either start it if necessary (with the |
957 | value), or reset the running timer to the repeat value.</p> |
977 | <code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p> |
958 | <p>This sounds a bit complicated, but here is a useful and typical |
978 | <p>This sounds a bit complicated, but here is a useful and typical |
959 | example: Imagine you have a tcp connection and you want a so-called |
979 | example: Imagine you have a tcp connection and you want a so-called idle |
960 | idle timeout, that is, you want to be called when there have been, |
980 | timeout, that is, you want to be called when there have been, say, 60 |
961 | say, 60 seconds of inactivity on the socket. The easiest way to do |
981 | seconds of inactivity on the socket. The easiest way to do this is to |
962 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
982 | configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call |
963 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
983 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
964 | you go into an idle state where you do not expect data to travel on the |
984 | you go into an idle state where you do not expect data to travel on the |
965 | socket, you can stop the timer, and again will automatically restart it if |
985 | socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will |
966 | need be.</p> |
986 | automatically restart it if need be.</p> |
967 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
987 | <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code> |
968 | and only ever use the <code>repeat</code> value:</p> |
988 | altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p> |
969 | <pre> ev_timer_init (timer, callback, 0., 5.); |
989 | <pre> ev_timer_init (timer, callback, 0., 5.); |
970 | ev_timer_again (loop, timer); |
990 | ev_timer_again (loop, timer); |
971 | ... |
991 | ... |
972 | timer->again = 17.; |
992 | timer->again = 17.; |
973 | ev_timer_again (loop, timer); |
993 | ev_timer_again (loop, timer); |
974 | ... |
994 | ... |
975 | timer->again = 10.; |
995 | timer->again = 10.; |
976 | ev_timer_again (loop, timer); |
996 | ev_timer_again (loop, timer); |
977 | |
997 | |
978 | </pre> |
998 | </pre> |
979 | <p>This is more efficient then stopping/starting the timer eahc time you want |
999 | <p>This is more slightly efficient then stopping/starting the timer each time |
980 | to modify its timeout value.</p> |
1000 | you want to modify its timeout value.</p> |
981 | </dd> |
1001 | </dd> |
982 | <dt>ev_tstamp repeat [read-write]</dt> |
1002 | <dt>ev_tstamp repeat [read-write]</dt> |
983 | <dd> |
1003 | <dd> |
984 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
1004 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
985 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
1005 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
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1246 | <p>The path does not need to exist: changing from "path exists" to "path does |
1266 | <p>The path does not need to exist: changing from "path exists" to "path does |
1247 | not exist" is a status change like any other. The condition "path does |
1267 | not exist" is a status change like any other. The condition "path does |
1248 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1268 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1249 | otherwise always forced to be at least one) and all the other fields of |
1269 | otherwise always forced to be at least one) and all the other fields of |
1250 | the stat buffer having unspecified contents.</p> |
1270 | the stat buffer having unspecified contents.</p> |
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1271 | <p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is |
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1272 | relative and your working directory changes, the behaviour is undefined.</p> |
1251 | <p>Since there is no standard to do this, the portable implementation simply |
1273 | <p>Since there is no standard to do this, the portable implementation simply |
1252 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
1274 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
1253 | can specify a recommended polling interval for this case. If you specify |
1275 | can specify a recommended polling interval for this case. If you specify |
1254 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1276 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1255 | unspecified default</i> value will be used (which you can expect to be around |
1277 | unspecified default</i> value will be used (which you can expect to be around |
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1817 | <dd> |
1839 | <dd> |
1818 | <p>Similar to the other two macros, this gives you the value of the default |
1840 | <p>Similar to the other two macros, this gives you the value of the default |
1819 | loop, if multiple loops are supported ("ev loop default").</p> |
1841 | loop, if multiple loops are supported ("ev loop default").</p> |
1820 | </dd> |
1842 | </dd> |
1821 | </dl> |
1843 | </dl> |
1822 | <p>Example: Declare and initialise a check watcher, working regardless of |
1844 | <p>Example: Declare and initialise a check watcher, utilising the above |
1823 | wether multiple loops are supported or not.</p> |
1845 | macros so it will work regardless of wether multiple loops are supported |
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|
1846 | or not.</p> |
1824 | <pre> static void |
1847 | <pre> static void |
1825 | check_cb (EV_P_ ev_timer *w, int revents) |
1848 | check_cb (EV_P_ ev_timer *w, int revents) |
1826 | { |
1849 | { |
1827 | ev_check_stop (EV_A_ w); |
1850 | ev_check_stop (EV_A_ w); |
1828 | } |
1851 | } |
1829 | |
1852 | |
1830 | ev_check check; |
1853 | ev_check check; |
1831 | ev_check_init (&check, check_cb); |
1854 | ev_check_init (&check, check_cb); |
1832 | ev_check_start (EV_DEFAULT_ &check); |
1855 | ev_check_start (EV_DEFAULT_ &check); |
1833 | ev_loop (EV_DEFAULT_ 0); |
1856 | ev_loop (EV_DEFAULT_ 0); |
1834 | |
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1835 | |
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1836 | |
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1837 | |
1857 | |
1838 | </pre> |
1858 | </pre> |
1839 | |
1859 | |
1840 | </div> |
1860 | </div> |
1841 | <h1 id="EMBEDDING">EMBEDDING</h1> |
1861 | <h1 id="EMBEDDING">EMBEDDING</h1> |
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1883 | ev_vars.h |
1903 | ev_vars.h |
1884 | ev_wrap.h |
1904 | ev_wrap.h |
1885 | |
1905 | |
1886 | ev_win32.c required on win32 platforms only |
1906 | ev_win32.c required on win32 platforms only |
1887 | |
1907 | |
1888 | ev_select.c only when select backend is enabled (which is by default) |
1908 | ev_select.c only when select backend is enabled (which is enabled by default) |
1889 | ev_poll.c only when poll backend is enabled (disabled by default) |
1909 | ev_poll.c only when poll backend is enabled (disabled by default) |
1890 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1910 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1891 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1911 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1892 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1912 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1893 | |
1913 | |
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2135 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2155 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2136 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2156 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2137 | will be compiled. It is pretty complex because it provides its own header |
2157 | will be compiled. It is pretty complex because it provides its own header |
2138 | file.</p> |
2158 | file.</p> |
2139 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2159 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2140 | that everybody includes and which overrides some autoconf choices:</p> |
2160 | that everybody includes and which overrides some configure choices:</p> |
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|
2161 | <pre> #define EV_MINIMAL 1 |
2141 | <pre> #define EV_USE_POLL 0 |
2162 | #define EV_USE_POLL 0 |
2142 | #define EV_MULTIPLICITY 0 |
2163 | #define EV_MULTIPLICITY 0 |
2143 | #define EV_PERIODICS 0 |
2164 | #define EV_PERIODIC_ENABLE 0 |
|
|
2165 | #define EV_STAT_ENABLE 0 |
|
|
2166 | #define EV_FORK_ENABLE 0 |
2144 | #define EV_CONFIG_H <config.h> |
2167 | #define EV_CONFIG_H <config.h> |
|
|
2168 | #define EV_MINPRI 0 |
|
|
2169 | #define EV_MAXPRI 0 |
2145 | |
2170 | |
2146 | #include "ev++.h" |
2171 | #include "ev++.h" |
2147 | |
2172 | |
2148 | </pre> |
2173 | </pre> |
2149 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
2174 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |