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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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12 | <body> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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325 | 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 |
326 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
326 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
327 | 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 |
328 | 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 |
329 | 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 noticeable (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> |
330 | </dd> |
347 | </dd> |
331 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
348 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
332 | <dd> |
349 | <dd> |
333 | <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 |
334 | 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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464 | <dd> |
481 | <dd> |
465 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
482 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
466 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
483 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
467 | after fork, and how you do this is entirely your own problem.</p> |
484 | after fork, and how you do this is entirely your own problem.</p> |
468 | </dd> |
485 | </dd> |
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|
486 | <dt>unsigned int ev_loop_count (loop)</dt> |
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|
487 | <dd> |
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|
488 | <p>Returns the count of loop iterations for the loop, which is identical to |
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489 | the number of times libev did poll for new events. It starts at <code>0</code> and |
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490 | happily wraps around with enough iterations.</p> |
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|
491 | <p>This value can sometimes be useful as a generation counter of sorts (it |
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492 | "ticks" the number of loop iterations), as it roughly corresponds with |
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493 | <code>ev_prepare</code> and <code>ev_check</code> calls.</p> |
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494 | </dd> |
469 | <dt>unsigned int ev_backend (loop)</dt> |
495 | <dt>unsigned int ev_backend (loop)</dt> |
470 | <dd> |
496 | <dd> |
471 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
497 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
472 | use.</p> |
498 | use.</p> |
473 | </dd> |
499 | </dd> |
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752 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
778 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
753 | <dd> |
779 | <dd> |
754 | <p>Change the callback. You can change the callback at virtually any time |
780 | <p>Change the callback. You can change the callback at virtually any time |
755 | (modulo threads).</p> |
781 | (modulo threads).</p> |
756 | </dd> |
782 | </dd> |
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783 | <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt> |
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784 | <dt>int ev_priority (ev_TYPE *watcher)</dt> |
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785 | <dd> |
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786 | <p>Set and query the priority of the watcher. The priority is a small |
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787 | integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code> |
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788 | (default: <code>-2</code>). Pending watchers with higher priority will be invoked |
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789 | before watchers with lower priority, but priority will not keep watchers |
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790 | from being executed (except for <code>ev_idle</code> watchers).</p> |
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791 | <p>This means that priorities are <i>only</i> used for ordering callback |
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792 | invocation after new events have been received. This is useful, for |
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793 | example, to reduce latency after idling, or more often, to bind two |
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794 | watchers on the same event and make sure one is called first.</p> |
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795 | <p>If you need to suppress invocation when higher priority events are pending |
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796 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
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797 | <p>The default priority used by watchers when no priority has been set is |
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798 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
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799 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
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800 | fine, as long as you do not mind that the priority value you query might |
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801 | or might not have been adjusted to be within valid range.</p> |
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802 | </dd> |
757 | </dl> |
803 | </dl> |
758 | |
804 | |
759 | |
805 | |
760 | |
806 | |
761 | |
807 | |
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952 | </dd> |
998 | </dd> |
953 | <dt>ev_timer_again (loop)</dt> |
999 | <dt>ev_timer_again (loop)</dt> |
954 | <dd> |
1000 | <dd> |
955 | <p>This will act as if the timer timed out and restart it again if it is |
1001 | <p>This will act as if the timer timed out and restart it again if it is |
956 | repeating. The exact semantics are:</p> |
1002 | repeating. The exact semantics are:</p> |
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|
1003 | <p>If the timer is pending, its pending status is cleared.</p> |
957 | <p>If the timer is started but nonrepeating, stop it.</p> |
1004 | <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p> |
958 | <p>If the timer is repeating, either start it if necessary (with the repeat |
1005 | <p>If the timer is repeating, either start it if necessary (with the |
959 | value), or reset the running timer to the repeat value.</p> |
1006 | <code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p> |
960 | <p>This sounds a bit complicated, but here is a useful and typical |
1007 | <p>This sounds a bit complicated, but here is a useful and typical |
961 | example: Imagine you have a tcp connection and you want a so-called |
1008 | example: Imagine you have a tcp connection and you want a so-called idle |
962 | idle timeout, that is, you want to be called when there have been, |
1009 | timeout, that is, you want to be called when there have been, say, 60 |
963 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1010 | seconds of inactivity on the socket. The easiest way to do this is to |
964 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
1011 | configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call |
965 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
1012 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
966 | you go into an idle state where you do not expect data to travel on the |
1013 | you go into an idle state where you do not expect data to travel on the |
967 | socket, you can stop the timer, and again will automatically restart it if |
1014 | socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will |
968 | need be.</p> |
1015 | automatically restart it if need be.</p> |
969 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
1016 | <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code> |
970 | and only ever use the <code>repeat</code> value:</p> |
1017 | altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p> |
971 | <pre> ev_timer_init (timer, callback, 0., 5.); |
1018 | <pre> ev_timer_init (timer, callback, 0., 5.); |
972 | ev_timer_again (loop, timer); |
1019 | ev_timer_again (loop, timer); |
973 | ... |
1020 | ... |
974 | timer->again = 17.; |
1021 | timer->again = 17.; |
975 | ev_timer_again (loop, timer); |
1022 | ev_timer_again (loop, timer); |
976 | ... |
1023 | ... |
977 | timer->again = 10.; |
1024 | timer->again = 10.; |
978 | ev_timer_again (loop, timer); |
1025 | ev_timer_again (loop, timer); |
979 | |
1026 | |
980 | </pre> |
1027 | </pre> |
981 | <p>This is more efficient then stopping/starting the timer eahc time you want |
1028 | <p>This is more slightly efficient then stopping/starting the timer each time |
982 | to modify its timeout value.</p> |
1029 | you want to modify its timeout value.</p> |
983 | </dd> |
1030 | </dd> |
984 | <dt>ev_tstamp repeat [read-write]</dt> |
1031 | <dt>ev_tstamp repeat [read-write]</dt> |
985 | <dd> |
1032 | <dd> |
986 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
1033 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
987 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
1034 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
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1248 | <p>The path does not need to exist: changing from "path exists" to "path does |
1295 | <p>The path does not need to exist: changing from "path exists" to "path does |
1249 | not exist" is a status change like any other. The condition "path does |
1296 | not exist" is a status change like any other. The condition "path does |
1250 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1297 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1251 | otherwise always forced to be at least one) and all the other fields of |
1298 | otherwise always forced to be at least one) and all the other fields of |
1252 | the stat buffer having unspecified contents.</p> |
1299 | the stat buffer having unspecified contents.</p> |
|
|
1300 | <p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is |
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1301 | relative and your working directory changes, the behaviour is undefined.</p> |
1253 | <p>Since there is no standard to do this, the portable implementation simply |
1302 | <p>Since there is no standard to do this, the portable implementation simply |
1254 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
1303 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
1255 | can specify a recommended polling interval for this case. If you specify |
1304 | can specify a recommended polling interval for this case. If you specify |
1256 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1305 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1257 | unspecified default</i> value will be used (which you can expect to be around |
1306 | unspecified default</i> value will be used (which you can expect to be around |
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1338 | </pre> |
1387 | </pre> |
1339 | |
1388 | |
1340 | </div> |
1389 | </div> |
1341 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1390 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1342 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1391 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1343 | <p>Idle watchers trigger events when there are no other events are pending |
1392 | <p>Idle watchers trigger events when no other events of the same or higher |
1344 | (prepare, check and other idle watchers do not count). That is, as long |
1393 | priority are pending (prepare, check and other idle watchers do not |
1345 | as your process is busy handling sockets or timeouts (or even signals, |
1394 | count).</p> |
1346 | imagine) it will not be triggered. But when your process is idle all idle |
1395 | <p>That is, as long as your process is busy handling sockets or timeouts |
1347 | watchers are being called again and again, once per event loop iteration - |
1396 | (or even signals, imagine) of the same or higher priority it will not be |
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|
1397 | triggered. But when your process is idle (or only lower-priority watchers |
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1398 | are pending), the idle watchers are being called once per event loop |
1348 | until stopped, that is, or your process receives more events and becomes |
1399 | iteration - until stopped, that is, or your process receives more events |
1349 | busy.</p> |
1400 | and becomes busy again with higher priority stuff.</p> |
1350 | <p>The most noteworthy effect is that as long as any idle watchers are |
1401 | <p>The most noteworthy effect is that as long as any idle watchers are |
1351 | active, the process will not block when waiting for new events.</p> |
1402 | active, the process will not block when waiting for new events.</p> |
1352 | <p>Apart from keeping your process non-blocking (which is a useful |
1403 | <p>Apart from keeping your process non-blocking (which is a useful |
1353 | effect on its own sometimes), idle watchers are a good place to do |
1404 | effect on its own sometimes), idle watchers are a good place to do |
1354 | "pseudo-background processing", or delay processing stuff to after the |
1405 | "pseudo-background processing", or delay processing stuff to after the |
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1444 | |
1495 | |
1445 | // create io watchers for each fd and a timer before blocking |
1496 | // create io watchers for each fd and a timer before blocking |
1446 | static void |
1497 | static void |
1447 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1498 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1448 | { |
1499 | { |
1449 | int timeout = 3600000;truct pollfd fds [nfd]; |
1500 | int timeout = 3600000; |
|
|
1501 | struct pollfd fds [nfd]; |
1450 | // actual code will need to loop here and realloc etc. |
1502 | // actual code will need to loop here and realloc etc. |
1451 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1503 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1452 | |
1504 | |
1453 | /* the callback is illegal, but won't be called as we stop during check */ |
1505 | /* the callback is illegal, but won't be called as we stop during check */ |
1454 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1506 | ev_timer_init (&tw, 0, timeout * 1e-3); |
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1819 | <dd> |
1871 | <dd> |
1820 | <p>Similar to the other two macros, this gives you the value of the default |
1872 | <p>Similar to the other two macros, this gives you the value of the default |
1821 | loop, if multiple loops are supported ("ev loop default").</p> |
1873 | loop, if multiple loops are supported ("ev loop default").</p> |
1822 | </dd> |
1874 | </dd> |
1823 | </dl> |
1875 | </dl> |
1824 | <p>Example: Declare and initialise a check watcher, working regardless of |
1876 | <p>Example: Declare and initialise a check watcher, utilising the above |
1825 | wether multiple loops are supported or not.</p> |
1877 | macros so it will work regardless of wether multiple loops are supported |
|
|
1878 | or not.</p> |
1826 | <pre> static void |
1879 | <pre> static void |
1827 | check_cb (EV_P_ ev_timer *w, int revents) |
1880 | check_cb (EV_P_ ev_timer *w, int revents) |
1828 | { |
1881 | { |
1829 | ev_check_stop (EV_A_ w); |
1882 | ev_check_stop (EV_A_ w); |
1830 | } |
1883 | } |
1831 | |
1884 | |
1832 | ev_check check; |
1885 | ev_check check; |
1833 | ev_check_init (&check, check_cb); |
1886 | ev_check_init (&check, check_cb); |
1834 | ev_check_start (EV_DEFAULT_ &check); |
1887 | ev_check_start (EV_DEFAULT_ &check); |
1835 | ev_loop (EV_DEFAULT_ 0); |
1888 | ev_loop (EV_DEFAULT_ 0); |
1836 | |
|
|
1837 | |
|
|
1838 | |
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|
1839 | |
1889 | |
1840 | </pre> |
1890 | </pre> |
1841 | |
1891 | |
1842 | </div> |
1892 | </div> |
1843 | <h1 id="EMBEDDING">EMBEDDING</h1> |
1893 | <h1 id="EMBEDDING">EMBEDDING</h1> |
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1885 | ev_vars.h |
1935 | ev_vars.h |
1886 | ev_wrap.h |
1936 | ev_wrap.h |
1887 | |
1937 | |
1888 | ev_win32.c required on win32 platforms only |
1938 | ev_win32.c required on win32 platforms only |
1889 | |
1939 | |
1890 | ev_select.c only when select backend is enabled (which is by default) |
1940 | ev_select.c only when select backend is enabled (which is enabled by default) |
1891 | ev_poll.c only when poll backend is enabled (disabled by default) |
1941 | ev_poll.c only when poll backend is enabled (disabled by default) |
1892 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1942 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1893 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1943 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1894 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1944 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1895 | |
1945 | |
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2063 | argument. Instead, all functions act on the single default loop.</p> |
2113 | argument. Instead, all functions act on the single default loop.</p> |
2064 | </dd> |
2114 | </dd> |
2065 | <dt>EV_PERIODIC_ENABLE</dt> |
2115 | <dt>EV_PERIODIC_ENABLE</dt> |
2066 | <dd> |
2116 | <dd> |
2067 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2117 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
|
|
2118 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
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|
2119 | code.</p> |
|
|
2120 | </dd> |
|
|
2121 | <dt>EV_IDLE_ENABLE</dt> |
|
|
2122 | <dd> |
|
|
2123 | <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If |
2068 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2124 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2069 | code.</p> |
2125 | code.</p> |
2070 | </dd> |
2126 | </dd> |
2071 | <dt>EV_EMBED_ENABLE</dt> |
2127 | <dt>EV_EMBED_ENABLE</dt> |
2072 | <dd> |
2128 | <dd> |
… | |
… | |
2137 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2193 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2138 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2194 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2139 | will be compiled. It is pretty complex because it provides its own header |
2195 | will be compiled. It is pretty complex because it provides its own header |
2140 | file.</p> |
2196 | file.</p> |
2141 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2197 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2142 | that everybody includes and which overrides some autoconf choices:</p> |
2198 | that everybody includes and which overrides some configure choices:</p> |
|
|
2199 | <pre> #define EV_MINIMAL 1 |
2143 | <pre> #define EV_USE_POLL 0 |
2200 | #define EV_USE_POLL 0 |
2144 | #define EV_MULTIPLICITY 0 |
2201 | #define EV_MULTIPLICITY 0 |
2145 | #define EV_PERIODICS 0 |
2202 | #define EV_PERIODIC_ENABLE 0 |
|
|
2203 | #define EV_STAT_ENABLE 0 |
|
|
2204 | #define EV_FORK_ENABLE 0 |
2146 | #define EV_CONFIG_H <config.h> |
2205 | #define EV_CONFIG_H <config.h> |
|
|
2206 | #define EV_MINPRI 0 |
|
|
2207 | #define EV_MAXPRI 0 |
2147 | |
2208 | |
2148 | #include "ev++.h" |
2209 | #include "ev++.h" |
2149 | |
2210 | |
2150 | </pre> |
2211 | </pre> |
2151 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
2212 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |