… | |
… | |
47 | |
47 | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
|
|
52 | |
|
|
53 | The newest version of this document is also available as a html-formatted |
|
|
54 | web page you might find easier to navigate when reading it for the first |
|
|
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
52 | |
56 | |
53 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occuring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
… | |
… | |
163 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
167 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
164 | recommended ones. |
168 | recommended ones. |
165 | |
169 | |
166 | See the description of C<ev_embed> watchers for more info. |
170 | See the description of C<ev_embed> watchers for more info. |
167 | |
171 | |
168 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
172 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
169 | |
173 | |
170 | Sets the allocation function to use (the prototype and semantics are |
174 | Sets the allocation function to use (the prototype is similar - the |
171 | identical to the realloc C function). It is used to allocate and free |
175 | semantics is identical - to the realloc C function). It is used to |
172 | memory (no surprises here). If it returns zero when memory needs to be |
176 | allocate and free memory (no surprises here). If it returns zero when |
173 | allocated, the library might abort or take some potentially destructive |
177 | memory needs to be allocated, the library might abort or take some |
174 | action. The default is your system realloc function. |
178 | potentially destructive action. The default is your system realloc |
|
|
179 | function. |
175 | |
180 | |
176 | You could override this function in high-availability programs to, say, |
181 | You could override this function in high-availability programs to, say, |
177 | free some memory if it cannot allocate memory, to use a special allocator, |
182 | free some memory if it cannot allocate memory, to use a special allocator, |
178 | or even to sleep a while and retry until some memory is available. |
183 | or even to sleep a while and retry until some memory is available. |
179 | |
184 | |
… | |
… | |
265 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
270 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
266 | override the flags completely if it is found in the environment. This is |
271 | override the flags completely if it is found in the environment. This is |
267 | useful to try out specific backends to test their performance, or to work |
272 | useful to try out specific backends to test their performance, or to work |
268 | around bugs. |
273 | around bugs. |
269 | |
274 | |
|
|
275 | =item C<EVFLAG_FORKCHECK> |
|
|
276 | |
|
|
277 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
278 | a fork, you can also make libev check for a fork in each iteration by |
|
|
279 | enabling this flag. |
|
|
280 | |
|
|
281 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
282 | and thus this might slow down your event loop if you do a lot of loop |
|
|
283 | iterations and little real work, but is usually not noticeable (on my |
|
|
284 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
285 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
286 | C<pthread_atfork> which is even faster). |
|
|
287 | |
|
|
288 | The big advantage of this flag is that you can forget about fork (and |
|
|
289 | forget about forgetting to tell libev about forking) when you use this |
|
|
290 | flag. |
|
|
291 | |
|
|
292 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
293 | environment variable. |
|
|
294 | |
270 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
295 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
271 | |
296 | |
272 | This is your standard select(2) backend. Not I<completely> standard, as |
297 | This is your standard select(2) backend. Not I<completely> standard, as |
273 | libev tries to roll its own fd_set with no limits on the number of fds, |
298 | libev tries to roll its own fd_set with no limits on the number of fds, |
274 | but if that fails, expect a fairly low limit on the number of fds when |
299 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
408 | =item ev_loop_fork (loop) |
433 | =item ev_loop_fork (loop) |
409 | |
434 | |
410 | Like C<ev_default_fork>, but acts on an event loop created by |
435 | Like C<ev_default_fork>, but acts on an event loop created by |
411 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
436 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
412 | after fork, and how you do this is entirely your own problem. |
437 | after fork, and how you do this is entirely your own problem. |
|
|
438 | |
|
|
439 | =item unsigned int ev_loop_count (loop) |
|
|
440 | |
|
|
441 | Returns the count of loop iterations for the loop, which is identical to |
|
|
442 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
443 | happily wraps around with enough iterations. |
|
|
444 | |
|
|
445 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
446 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
447 | C<ev_prepare> and C<ev_check> calls. |
413 | |
448 | |
414 | =item unsigned int ev_backend (loop) |
449 | =item unsigned int ev_backend (loop) |
415 | |
450 | |
416 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
451 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
417 | use. |
452 | use. |
… | |
… | |
713 | =item ev_cb_set (ev_TYPE *watcher, callback) |
748 | =item ev_cb_set (ev_TYPE *watcher, callback) |
714 | |
749 | |
715 | Change the callback. You can change the callback at virtually any time |
750 | Change the callback. You can change the callback at virtually any time |
716 | (modulo threads). |
751 | (modulo threads). |
717 | |
752 | |
|
|
753 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
754 | |
|
|
755 | =item int ev_priority (ev_TYPE *watcher) |
|
|
756 | |
|
|
757 | Set and query the priority of the watcher. The priority is a small |
|
|
758 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
759 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
760 | before watchers with lower priority, but priority will not keep watchers |
|
|
761 | from being executed (except for C<ev_idle> watchers). |
|
|
762 | |
|
|
763 | This means that priorities are I<only> used for ordering callback |
|
|
764 | invocation after new events have been received. This is useful, for |
|
|
765 | example, to reduce latency after idling, or more often, to bind two |
|
|
766 | watchers on the same event and make sure one is called first. |
|
|
767 | |
|
|
768 | If you need to suppress invocation when higher priority events are pending |
|
|
769 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
770 | |
|
|
771 | The default priority used by watchers when no priority has been set is |
|
|
772 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
773 | |
|
|
774 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
775 | fine, as long as you do not mind that the priority value you query might |
|
|
776 | or might not have been adjusted to be within valid range. |
|
|
777 | |
718 | =back |
778 | =back |
719 | |
779 | |
720 | |
780 | |
721 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
781 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
722 | |
782 | |
… | |
… | |
827 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
887 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
828 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
888 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
829 | |
889 | |
830 | If you cannot run the fd in non-blocking mode (for example you should not |
890 | If you cannot run the fd in non-blocking mode (for example you should not |
831 | play around with an Xlib connection), then you have to seperately re-test |
891 | play around with an Xlib connection), then you have to seperately re-test |
832 | wether a file descriptor is really ready with a known-to-be good interface |
892 | whether a file descriptor is really ready with a known-to-be good interface |
833 | such as poll (fortunately in our Xlib example, Xlib already does this on |
893 | such as poll (fortunately in our Xlib example, Xlib already does this on |
834 | its own, so its quite safe to use). |
894 | its own, so its quite safe to use). |
835 | |
895 | |
836 | =over 4 |
896 | =over 4 |
837 | |
897 | |
… | |
… | |
915 | =item ev_timer_again (loop) |
975 | =item ev_timer_again (loop) |
916 | |
976 | |
917 | This will act as if the timer timed out and restart it again if it is |
977 | This will act as if the timer timed out and restart it again if it is |
918 | repeating. The exact semantics are: |
978 | repeating. The exact semantics are: |
919 | |
979 | |
|
|
980 | If the timer is pending, its pending status is cleared. |
|
|
981 | |
920 | If the timer is started but nonrepeating, stop it. |
982 | If the timer is started but nonrepeating, stop it (as if it timed out). |
921 | |
983 | |
922 | If the timer is repeating, either start it if necessary (with the repeat |
984 | If the timer is repeating, either start it if necessary (with the |
923 | value), or reset the running timer to the repeat value. |
985 | C<repeat> value), or reset the running timer to the C<repeat> value. |
924 | |
986 | |
925 | This sounds a bit complicated, but here is a useful and typical |
987 | This sounds a bit complicated, but here is a useful and typical |
926 | example: Imagine you have a tcp connection and you want a so-called |
988 | example: Imagine you have a tcp connection and you want a so-called idle |
927 | idle timeout, that is, you want to be called when there have been, |
989 | timeout, that is, you want to be called when there have been, say, 60 |
928 | say, 60 seconds of inactivity on the socket. The easiest way to do |
990 | seconds of inactivity on the socket. The easiest way to do this is to |
929 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
991 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
930 | C<ev_timer_again> each time you successfully read or write some data. If |
992 | C<ev_timer_again> each time you successfully read or write some data. If |
931 | you go into an idle state where you do not expect data to travel on the |
993 | you go into an idle state where you do not expect data to travel on the |
932 | socket, you can stop the timer, and again will automatically restart it if |
994 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
933 | need be. |
995 | automatically restart it if need be. |
934 | |
996 | |
935 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
997 | That means you can ignore the C<after> value and C<ev_timer_start> |
936 | and only ever use the C<repeat> value: |
998 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
937 | |
999 | |
938 | ev_timer_init (timer, callback, 0., 5.); |
1000 | ev_timer_init (timer, callback, 0., 5.); |
939 | ev_timer_again (loop, timer); |
1001 | ev_timer_again (loop, timer); |
940 | ... |
1002 | ... |
941 | timer->again = 17.; |
1003 | timer->again = 17.; |
942 | ev_timer_again (loop, timer); |
1004 | ev_timer_again (loop, timer); |
943 | ... |
1005 | ... |
944 | timer->again = 10.; |
1006 | timer->again = 10.; |
945 | ev_timer_again (loop, timer); |
1007 | ev_timer_again (loop, timer); |
946 | |
1008 | |
947 | This is more efficient then stopping/starting the timer eahc time you want |
1009 | This is more slightly efficient then stopping/starting the timer each time |
948 | to modify its timeout value. |
1010 | you want to modify its timeout value. |
949 | |
1011 | |
950 | =item ev_tstamp repeat [read-write] |
1012 | =item ev_tstamp repeat [read-write] |
951 | |
1013 | |
952 | The current C<repeat> value. Will be used each time the watcher times out |
1014 | The current C<repeat> value. Will be used each time the watcher times out |
953 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1015 | or C<ev_timer_again> is called and determines the next timeout (if any), |
… | |
… | |
1221 | The path does not need to exist: changing from "path exists" to "path does |
1283 | The path does not need to exist: changing from "path exists" to "path does |
1222 | not exist" is a status change like any other. The condition "path does |
1284 | not exist" is a status change like any other. The condition "path does |
1223 | not exist" is signified by the C<st_nlink> field being zero (which is |
1285 | not exist" is signified by the C<st_nlink> field being zero (which is |
1224 | otherwise always forced to be at least one) and all the other fields of |
1286 | otherwise always forced to be at least one) and all the other fields of |
1225 | the stat buffer having unspecified contents. |
1287 | the stat buffer having unspecified contents. |
|
|
1288 | |
|
|
1289 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1290 | relative and your working directory changes, the behaviour is undefined. |
1226 | |
1291 | |
1227 | Since there is no standard to do this, the portable implementation simply |
1292 | Since there is no standard to do this, the portable implementation simply |
1228 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1293 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1229 | can specify a recommended polling interval for this case. If you specify |
1294 | can specify a recommended polling interval for this case. If you specify |
1230 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1295 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
… | |
… | |
1315 | ev_stat_start (loop, &passwd); |
1380 | ev_stat_start (loop, &passwd); |
1316 | |
1381 | |
1317 | |
1382 | |
1318 | =head2 C<ev_idle> - when you've got nothing better to do... |
1383 | =head2 C<ev_idle> - when you've got nothing better to do... |
1319 | |
1384 | |
1320 | Idle watchers trigger events when there are no other events are pending |
1385 | Idle watchers trigger events when no other events of the same or higher |
1321 | (prepare, check and other idle watchers do not count). That is, as long |
1386 | priority are pending (prepare, check and other idle watchers do not |
1322 | as your process is busy handling sockets or timeouts (or even signals, |
1387 | count). |
1323 | imagine) it will not be triggered. But when your process is idle all idle |
1388 | |
1324 | watchers are being called again and again, once per event loop iteration - |
1389 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1390 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1391 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1392 | are pending), the idle watchers are being called once per event loop |
1325 | until stopped, that is, or your process receives more events and becomes |
1393 | iteration - until stopped, that is, or your process receives more events |
1326 | busy. |
1394 | and becomes busy again with higher priority stuff. |
1327 | |
1395 | |
1328 | The most noteworthy effect is that as long as any idle watchers are |
1396 | The most noteworthy effect is that as long as any idle watchers are |
1329 | active, the process will not block when waiting for new events. |
1397 | active, the process will not block when waiting for new events. |
1330 | |
1398 | |
1331 | Apart from keeping your process non-blocking (which is a useful |
1399 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
1431 | |
1499 | |
1432 | // create io watchers for each fd and a timer before blocking |
1500 | // create io watchers for each fd and a timer before blocking |
1433 | static void |
1501 | static void |
1434 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1502 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1435 | { |
1503 | { |
1436 | int timeout = 3600000;truct pollfd fds [nfd]; |
1504 | int timeout = 3600000; |
|
|
1505 | struct pollfd fds [nfd]; |
1437 | // actual code will need to loop here and realloc etc. |
1506 | // actual code will need to loop here and realloc etc. |
1438 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1507 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1439 | |
1508 | |
1440 | /* the callback is illegal, but won't be called as we stop during check */ |
1509 | /* the callback is illegal, but won't be called as we stop during check */ |
1441 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1510 | ev_timer_init (&tw, 0, timeout * 1e-3); |
… | |
… | |
1675 | |
1744 | |
1676 | To use it, |
1745 | To use it, |
1677 | |
1746 | |
1678 | #include <ev++.h> |
1747 | #include <ev++.h> |
1679 | |
1748 | |
1680 | (it is not installed by default). This automatically includes F<ev.h> |
1749 | This automatically includes F<ev.h> and puts all of its definitions (many |
1681 | and puts all of its definitions (many of them macros) into the global |
1750 | of them macros) into the global namespace. All C++ specific things are |
1682 | namespace. All C++ specific things are put into the C<ev> namespace. |
1751 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1752 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1683 | |
1753 | |
1684 | It should support all the same embedding options as F<ev.h>, most notably |
1754 | Care has been taken to keep the overhead low. The only data member added |
1685 | C<EV_MULTIPLICITY>. |
1755 | to the C-style watchers is the event loop the watcher is associated with |
|
|
1756 | (or no additional members at all if you disable C<EV_MULTIPLICITY> when |
|
|
1757 | embedding libev). |
|
|
1758 | |
|
|
1759 | Currently, functions and static and non-static member functions can be |
|
|
1760 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1761 | need one additional pointer for context. If you need support for other |
|
|
1762 | types of functors please contact the author (preferably after implementing |
|
|
1763 | it). |
1686 | |
1764 | |
1687 | Here is a list of things available in the C<ev> namespace: |
1765 | Here is a list of things available in the C<ev> namespace: |
1688 | |
1766 | |
1689 | =over 4 |
1767 | =over 4 |
1690 | |
1768 | |
… | |
… | |
1706 | |
1784 | |
1707 | All of those classes have these methods: |
1785 | All of those classes have these methods: |
1708 | |
1786 | |
1709 | =over 4 |
1787 | =over 4 |
1710 | |
1788 | |
1711 | =item ev::TYPE::TYPE (object *, object::method *) |
1789 | =item ev::TYPE::TYPE () |
1712 | |
1790 | |
1713 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1791 | =item ev::TYPE::TYPE (struct ev_loop *) |
1714 | |
1792 | |
1715 | =item ev::TYPE::~TYPE |
1793 | =item ev::TYPE::~TYPE |
1716 | |
1794 | |
1717 | The constructor takes a pointer to an object and a method pointer to |
1795 | The constructor (optionally) takes an event loop to associate the watcher |
1718 | the event handler callback to call in this class. The constructor calls |
1796 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1719 | C<ev_init> for you, which means you have to call the C<set> method |
1797 | |
1720 | before starting it. If you do not specify a loop then the constructor |
1798 | The constructor calls C<ev_init> for you, which means you have to call the |
1721 | automatically associates the default loop with this watcher. |
1799 | C<set> method before starting it. |
|
|
1800 | |
|
|
1801 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1802 | method to set a callback before you can start the watcher. |
|
|
1803 | |
|
|
1804 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1805 | not allow explicit template arguments for constructors). |
1722 | |
1806 | |
1723 | The destructor automatically stops the watcher if it is active. |
1807 | The destructor automatically stops the watcher if it is active. |
|
|
1808 | |
|
|
1809 | =item w->set<class, &class::method> (object *) |
|
|
1810 | |
|
|
1811 | This method sets the callback method to call. The method has to have a |
|
|
1812 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1813 | first argument and the C<revents> as second. The object must be given as |
|
|
1814 | parameter and is stored in the C<data> member of the watcher. |
|
|
1815 | |
|
|
1816 | This method synthesizes efficient thunking code to call your method from |
|
|
1817 | the C callback that libev requires. If your compiler can inline your |
|
|
1818 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1819 | your compiler is good :), then the method will be fully inlined into the |
|
|
1820 | thunking function, making it as fast as a direct C callback. |
|
|
1821 | |
|
|
1822 | Example: simple class declaration and watcher initialisation |
|
|
1823 | |
|
|
1824 | struct myclass |
|
|
1825 | { |
|
|
1826 | void io_cb (ev::io &w, int revents) { } |
|
|
1827 | } |
|
|
1828 | |
|
|
1829 | myclass obj; |
|
|
1830 | ev::io iow; |
|
|
1831 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1832 | |
|
|
1833 | =item w->set (void (*function)(watcher &w, int), void *data = 0) |
|
|
1834 | |
|
|
1835 | Also sets a callback, but uses a static method or plain function as |
|
|
1836 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
1837 | C<data> member and is free for you to use. |
|
|
1838 | |
|
|
1839 | See the method-C<set> above for more details. |
1724 | |
1840 | |
1725 | =item w->set (struct ev_loop *) |
1841 | =item w->set (struct ev_loop *) |
1726 | |
1842 | |
1727 | Associates a different C<struct ev_loop> with this watcher. You can only |
1843 | Associates a different C<struct ev_loop> with this watcher. You can only |
1728 | do this when the watcher is inactive (and not pending either). |
1844 | do this when the watcher is inactive (and not pending either). |
1729 | |
1845 | |
1730 | =item w->set ([args]) |
1846 | =item w->set ([args]) |
1731 | |
1847 | |
1732 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1848 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1733 | called at least once. Unlike the C counterpart, an active watcher gets |
1849 | called at least once. Unlike the C counterpart, an active watcher gets |
1734 | automatically stopped and restarted. |
1850 | automatically stopped and restarted when reconfiguring it with this |
|
|
1851 | method. |
1735 | |
1852 | |
1736 | =item w->start () |
1853 | =item w->start () |
1737 | |
1854 | |
1738 | Starts the watcher. Note that there is no C<loop> argument as the |
1855 | Starts the watcher. Note that there is no C<loop> argument, as the |
1739 | constructor already takes the loop. |
1856 | constructor already stores the event loop. |
1740 | |
1857 | |
1741 | =item w->stop () |
1858 | =item w->stop () |
1742 | |
1859 | |
1743 | Stops the watcher if it is active. Again, no C<loop> argument. |
1860 | Stops the watcher if it is active. Again, no C<loop> argument. |
1744 | |
1861 | |
… | |
… | |
1769 | |
1886 | |
1770 | myclass (); |
1887 | myclass (); |
1771 | } |
1888 | } |
1772 | |
1889 | |
1773 | myclass::myclass (int fd) |
1890 | myclass::myclass (int fd) |
1774 | : io (this, &myclass::io_cb), |
|
|
1775 | idle (this, &myclass::idle_cb) |
|
|
1776 | { |
1891 | { |
|
|
1892 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1893 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1894 | |
1777 | io.start (fd, ev::READ); |
1895 | io.start (fd, ev::READ); |
1778 | } |
1896 | } |
1779 | |
1897 | |
1780 | |
1898 | |
1781 | =head1 MACRO MAGIC |
1899 | =head1 MACRO MAGIC |
1782 | |
1900 | |
1783 | Libev can be compiled with a variety of options, the most fundemantal is |
1901 | Libev can be compiled with a variety of options, the most fundemantal is |
1784 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
1902 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
1785 | callbacks have an initial C<struct ev_loop *> argument. |
1903 | callbacks have an initial C<struct ev_loop *> argument. |
1786 | |
1904 | |
1787 | To make it easier to write programs that cope with either variant, the |
1905 | To make it easier to write programs that cope with either variant, the |
1788 | following macros are defined: |
1906 | following macros are defined: |
1789 | |
1907 | |
… | |
… | |
1822 | Similar to the other two macros, this gives you the value of the default |
1940 | Similar to the other two macros, this gives you the value of the default |
1823 | loop, if multiple loops are supported ("ev loop default"). |
1941 | loop, if multiple loops are supported ("ev loop default"). |
1824 | |
1942 | |
1825 | =back |
1943 | =back |
1826 | |
1944 | |
1827 | Example: Declare and initialise a check watcher, working regardless of |
1945 | Example: Declare and initialise a check watcher, utilising the above |
1828 | wether multiple loops are supported or not. |
1946 | macros so it will work regardless of whether multiple loops are supported |
|
|
1947 | or not. |
1829 | |
1948 | |
1830 | static void |
1949 | static void |
1831 | check_cb (EV_P_ ev_timer *w, int revents) |
1950 | check_cb (EV_P_ ev_timer *w, int revents) |
1832 | { |
1951 | { |
1833 | ev_check_stop (EV_A_ w); |
1952 | ev_check_stop (EV_A_ w); |
… | |
… | |
1835 | |
1954 | |
1836 | ev_check check; |
1955 | ev_check check; |
1837 | ev_check_init (&check, check_cb); |
1956 | ev_check_init (&check, check_cb); |
1838 | ev_check_start (EV_DEFAULT_ &check); |
1957 | ev_check_start (EV_DEFAULT_ &check); |
1839 | ev_loop (EV_DEFAULT_ 0); |
1958 | ev_loop (EV_DEFAULT_ 0); |
1840 | |
|
|
1841 | |
1959 | |
1842 | =head1 EMBEDDING |
1960 | =head1 EMBEDDING |
1843 | |
1961 | |
1844 | Libev can (and often is) directly embedded into host |
1962 | Libev can (and often is) directly embedded into host |
1845 | applications. Examples of applications that embed it include the Deliantra |
1963 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
1885 | ev_vars.h |
2003 | ev_vars.h |
1886 | ev_wrap.h |
2004 | ev_wrap.h |
1887 | |
2005 | |
1888 | ev_win32.c required on win32 platforms only |
2006 | ev_win32.c required on win32 platforms only |
1889 | |
2007 | |
1890 | ev_select.c only when select backend is enabled (which is by default) |
2008 | 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) |
2009 | 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) |
2010 | 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) |
2011 | 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) |
2012 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1895 | |
2013 | |
… | |
… | |
2058 | will have the C<struct ev_loop *> as first argument, and you can create |
2176 | will have the C<struct ev_loop *> as first argument, and you can create |
2059 | additional independent event loops. Otherwise there will be no support |
2177 | additional independent event loops. Otherwise there will be no support |
2060 | for multiple event loops and there is no first event loop pointer |
2178 | for multiple event loops and there is no first event loop pointer |
2061 | argument. Instead, all functions act on the single default loop. |
2179 | argument. Instead, all functions act on the single default loop. |
2062 | |
2180 | |
|
|
2181 | =item EV_MINPRI |
|
|
2182 | |
|
|
2183 | =item EV_MAXPRI |
|
|
2184 | |
|
|
2185 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2186 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2187 | provide for more priorities by overriding those symbols (usually defined |
|
|
2188 | to be C<-2> and C<2>, respectively). |
|
|
2189 | |
|
|
2190 | When doing priority-based operations, libev usually has to linearly search |
|
|
2191 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2192 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2193 | fine. |
|
|
2194 | |
|
|
2195 | If your embedding app does not need any priorities, defining these both to |
|
|
2196 | C<0> will save some memory and cpu. |
|
|
2197 | |
2063 | =item EV_PERIODIC_ENABLE |
2198 | =item EV_PERIODIC_ENABLE |
2064 | |
2199 | |
2065 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2200 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2201 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2202 | code. |
|
|
2203 | |
|
|
2204 | =item EV_IDLE_ENABLE |
|
|
2205 | |
|
|
2206 | If undefined or defined to be C<1>, then idle watchers are supported. If |
2066 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2207 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2067 | code. |
2208 | code. |
2068 | |
2209 | |
2069 | =item EV_EMBED_ENABLE |
2210 | =item EV_EMBED_ENABLE |
2070 | |
2211 | |
… | |
… | |
2137 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2278 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2138 | will be compiled. It is pretty complex because it provides its own header |
2279 | will be compiled. It is pretty complex because it provides its own header |
2139 | file. |
2280 | file. |
2140 | |
2281 | |
2141 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2282 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2142 | that everybody includes and which overrides some autoconf choices: |
2283 | that everybody includes and which overrides some configure choices: |
2143 | |
2284 | |
|
|
2285 | #define EV_MINIMAL 1 |
2144 | #define EV_USE_POLL 0 |
2286 | #define EV_USE_POLL 0 |
2145 | #define EV_MULTIPLICITY 0 |
2287 | #define EV_MULTIPLICITY 0 |
2146 | #define EV_PERIODICS 0 |
2288 | #define EV_PERIODIC_ENABLE 0 |
|
|
2289 | #define EV_STAT_ENABLE 0 |
|
|
2290 | #define EV_FORK_ENABLE 0 |
2147 | #define EV_CONFIG_H <config.h> |
2291 | #define EV_CONFIG_H <config.h> |
|
|
2292 | #define EV_MINPRI 0 |
|
|
2293 | #define EV_MAXPRI 0 |
2148 | |
2294 | |
2149 | #include "ev++.h" |
2295 | #include "ev++.h" |
2150 | |
2296 | |
2151 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2297 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2152 | |
2298 | |
… | |
… | |
2158 | |
2304 | |
2159 | In this section the complexities of (many of) the algorithms used inside |
2305 | In this section the complexities of (many of) the algorithms used inside |
2160 | libev will be explained. For complexity discussions about backends see the |
2306 | libev will be explained. For complexity discussions about backends see the |
2161 | documentation for C<ev_default_init>. |
2307 | documentation for C<ev_default_init>. |
2162 | |
2308 | |
|
|
2309 | All of the following are about amortised time: If an array needs to be |
|
|
2310 | extended, libev needs to realloc and move the whole array, but this |
|
|
2311 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2312 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2313 | it is much faster and asymptotically approaches constant time. |
|
|
2314 | |
2163 | =over 4 |
2315 | =over 4 |
2164 | |
2316 | |
2165 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2317 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2166 | |
2318 | |
|
|
2319 | This means that, when you have a watcher that triggers in one hour and |
|
|
2320 | there are 100 watchers that would trigger before that then inserting will |
|
|
2321 | have to skip those 100 watchers. |
|
|
2322 | |
2167 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2323 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2168 | |
2324 | |
|
|
2325 | That means that for changing a timer costs less than removing/adding them |
|
|
2326 | as only the relative motion in the event queue has to be paid for. |
|
|
2327 | |
2169 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2328 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2170 | |
2329 | |
|
|
2330 | These just add the watcher into an array or at the head of a list. |
2171 | =item Stopping check/prepare/idle watchers: O(1) |
2331 | =item Stopping check/prepare/idle watchers: O(1) |
2172 | |
2332 | |
2173 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2333 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2174 | |
2334 | |
|
|
2335 | These watchers are stored in lists then need to be walked to find the |
|
|
2336 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2337 | have many watchers waiting for the same fd or signal). |
|
|
2338 | |
2175 | =item Finding the next timer per loop iteration: O(1) |
2339 | =item Finding the next timer per loop iteration: O(1) |
2176 | |
2340 | |
2177 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2341 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2178 | |
2342 | |
|
|
2343 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2344 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2345 | |
2179 | =item Activating one watcher: O(1) |
2346 | =item Activating one watcher: O(1) |
2180 | |
2347 | |
|
|
2348 | =item Priority handling: O(number_of_priorities) |
|
|
2349 | |
|
|
2350 | Priorities are implemented by allocating some space for each |
|
|
2351 | priority. When doing priority-based operations, libev usually has to |
|
|
2352 | linearly search all the priorities. |
|
|
2353 | |
2181 | =back |
2354 | =back |
2182 | |
2355 | |
2183 | |
2356 | |
2184 | =head1 AUTHOR |
2357 | =head1 AUTHOR |
2185 | |
2358 | |