… | |
… | |
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 | |
… | |
… | |
274 | a fork, you can also make libev check for a fork in each iteration by |
278 | a fork, you can also make libev check for a fork in each iteration by |
275 | enabling this flag. |
279 | enabling this flag. |
276 | |
280 | |
277 | This works by calling C<getpid ()> on every iteration of the loop, |
281 | This works by calling C<getpid ()> on every iteration of the loop, |
278 | and thus this might slow down your event loop if you do a lot of loop |
282 | and thus this might slow down your event loop if you do a lot of loop |
279 | iterations and little real work, but is usually not noticable (on my |
283 | iterations and little real work, but is usually not noticeable (on my |
280 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
284 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
281 | without a syscall and thus I<very> fast, but my Linux system also has |
285 | without a syscall and thus I<very> fast, but my Linux system also has |
282 | C<pthread_atfork> which is even faster). |
286 | C<pthread_atfork> which is even faster). |
283 | |
287 | |
284 | The big advantage of this flag is that you can forget about fork (and |
288 | The big advantage of this flag is that you can forget about fork (and |
… | |
… | |
429 | =item ev_loop_fork (loop) |
433 | =item ev_loop_fork (loop) |
430 | |
434 | |
431 | 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 |
432 | 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 |
433 | 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. |
434 | |
448 | |
435 | =item unsigned int ev_backend (loop) |
449 | =item unsigned int ev_backend (loop) |
436 | |
450 | |
437 | 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 |
438 | use. |
452 | use. |
… | |
… | |
734 | =item ev_cb_set (ev_TYPE *watcher, callback) |
748 | =item ev_cb_set (ev_TYPE *watcher, callback) |
735 | |
749 | |
736 | 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 |
737 | (modulo threads). |
751 | (modulo threads). |
738 | |
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 | |
739 | =back |
778 | =back |
740 | |
779 | |
741 | |
780 | |
742 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
781 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
743 | |
782 | |
… | |
… | |
848 | 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 |
849 | 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. |
850 | |
889 | |
851 | 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 |
852 | 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 |
853 | 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 |
854 | 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 |
855 | its own, so its quite safe to use). |
894 | its own, so its quite safe to use). |
856 | |
895 | |
857 | =over 4 |
896 | =over 4 |
858 | |
897 | |
… | |
… | |
1341 | ev_stat_start (loop, &passwd); |
1380 | ev_stat_start (loop, &passwd); |
1342 | |
1381 | |
1343 | |
1382 | |
1344 | =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... |
1345 | |
1384 | |
1346 | 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 |
1347 | (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 |
1348 | as your process is busy handling sockets or timeouts (or even signals, |
1387 | count). |
1349 | imagine) it will not be triggered. But when your process is idle all idle |
1388 | |
1350 | 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 |
1351 | until stopped, that is, or your process receives more events and becomes |
1393 | iteration - until stopped, that is, or your process receives more events |
1352 | busy. |
1394 | and becomes busy again with higher priority stuff. |
1353 | |
1395 | |
1354 | 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 |
1355 | active, the process will not block when waiting for new events. |
1397 | active, the process will not block when waiting for new events. |
1356 | |
1398 | |
1357 | Apart from keeping your process non-blocking (which is a useful |
1399 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
1457 | |
1499 | |
1458 | // create io watchers for each fd and a timer before blocking |
1500 | // create io watchers for each fd and a timer before blocking |
1459 | static void |
1501 | static void |
1460 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1502 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1461 | { |
1503 | { |
1462 | int timeout = 3600000;truct pollfd fds [nfd]; |
1504 | int timeout = 3600000; |
|
|
1505 | struct pollfd fds [nfd]; |
1463 | // actual code will need to loop here and realloc etc. |
1506 | // actual code will need to loop here and realloc etc. |
1464 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1507 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1465 | |
1508 | |
1466 | /* 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 */ |
1467 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1510 | ev_timer_init (&tw, 0, timeout * 1e-3); |
… | |
… | |
1701 | |
1744 | |
1702 | To use it, |
1745 | To use it, |
1703 | |
1746 | |
1704 | #include <ev++.h> |
1747 | #include <ev++.h> |
1705 | |
1748 | |
1706 | (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 |
1707 | 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 |
1708 | 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>. |
1709 | |
1753 | |
1710 | 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 |
1711 | 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). |
1712 | |
1764 | |
1713 | 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: |
1714 | |
1766 | |
1715 | =over 4 |
1767 | =over 4 |
1716 | |
1768 | |
… | |
… | |
1732 | |
1784 | |
1733 | All of those classes have these methods: |
1785 | All of those classes have these methods: |
1734 | |
1786 | |
1735 | =over 4 |
1787 | =over 4 |
1736 | |
1788 | |
1737 | =item ev::TYPE::TYPE (object *, object::method *) |
1789 | =item ev::TYPE::TYPE () |
1738 | |
1790 | |
1739 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1791 | =item ev::TYPE::TYPE (struct ev_loop *) |
1740 | |
1792 | |
1741 | =item ev::TYPE::~TYPE |
1793 | =item ev::TYPE::~TYPE |
1742 | |
1794 | |
1743 | 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 |
1744 | the event handler callback to call in this class. The constructor calls |
1796 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1745 | C<ev_init> for you, which means you have to call the C<set> method |
1797 | |
1746 | 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 |
1747 | 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). |
1748 | |
1806 | |
1749 | 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. |
1750 | |
1840 | |
1751 | =item w->set (struct ev_loop *) |
1841 | =item w->set (struct ev_loop *) |
1752 | |
1842 | |
1753 | 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 |
1754 | do this when the watcher is inactive (and not pending either). |
1844 | do this when the watcher is inactive (and not pending either). |
1755 | |
1845 | |
1756 | =item w->set ([args]) |
1846 | =item w->set ([args]) |
1757 | |
1847 | |
1758 | 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 |
1759 | 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 |
1760 | automatically stopped and restarted. |
1850 | automatically stopped and restarted when reconfiguring it with this |
|
|
1851 | method. |
1761 | |
1852 | |
1762 | =item w->start () |
1853 | =item w->start () |
1763 | |
1854 | |
1764 | 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 |
1765 | constructor already takes the loop. |
1856 | constructor already stores the event loop. |
1766 | |
1857 | |
1767 | =item w->stop () |
1858 | =item w->stop () |
1768 | |
1859 | |
1769 | 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. |
1770 | |
1861 | |
… | |
… | |
1795 | |
1886 | |
1796 | myclass (); |
1887 | myclass (); |
1797 | } |
1888 | } |
1798 | |
1889 | |
1799 | myclass::myclass (int fd) |
1890 | myclass::myclass (int fd) |
1800 | : io (this, &myclass::io_cb), |
|
|
1801 | idle (this, &myclass::idle_cb) |
|
|
1802 | { |
1891 | { |
|
|
1892 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1893 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1894 | |
1803 | io.start (fd, ev::READ); |
1895 | io.start (fd, ev::READ); |
1804 | } |
1896 | } |
1805 | |
1897 | |
1806 | |
1898 | |
1807 | =head1 MACRO MAGIC |
1899 | =head1 MACRO MAGIC |
1808 | |
1900 | |
1809 | 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 |
1810 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
1902 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
1811 | callbacks have an initial C<struct ev_loop *> argument. |
1903 | callbacks have an initial C<struct ev_loop *> argument. |
1812 | |
1904 | |
1813 | 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 |
1814 | following macros are defined: |
1906 | following macros are defined: |
1815 | |
1907 | |
… | |
… | |
1848 | 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 |
1849 | loop, if multiple loops are supported ("ev loop default"). |
1941 | loop, if multiple loops are supported ("ev loop default"). |
1850 | |
1942 | |
1851 | =back |
1943 | =back |
1852 | |
1944 | |
1853 | Example: Declare and initialise a check watcher, working regardless of |
1945 | Example: Declare and initialise a check watcher, utilising the above |
1854 | wether multiple loops are supported or not. |
1946 | macros so it will work regardless of whether multiple loops are supported |
|
|
1947 | or not. |
1855 | |
1948 | |
1856 | static void |
1949 | static void |
1857 | check_cb (EV_P_ ev_timer *w, int revents) |
1950 | check_cb (EV_P_ ev_timer *w, int revents) |
1858 | { |
1951 | { |
1859 | ev_check_stop (EV_A_ w); |
1952 | ev_check_stop (EV_A_ w); |
… | |
… | |
1861 | |
1954 | |
1862 | ev_check check; |
1955 | ev_check check; |
1863 | ev_check_init (&check, check_cb); |
1956 | ev_check_init (&check, check_cb); |
1864 | ev_check_start (EV_DEFAULT_ &check); |
1957 | ev_check_start (EV_DEFAULT_ &check); |
1865 | ev_loop (EV_DEFAULT_ 0); |
1958 | ev_loop (EV_DEFAULT_ 0); |
1866 | |
|
|
1867 | |
1959 | |
1868 | =head1 EMBEDDING |
1960 | =head1 EMBEDDING |
1869 | |
1961 | |
1870 | Libev can (and often is) directly embedded into host |
1962 | Libev can (and often is) directly embedded into host |
1871 | applications. Examples of applications that embed it include the Deliantra |
1963 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
1911 | ev_vars.h |
2003 | ev_vars.h |
1912 | ev_wrap.h |
2004 | ev_wrap.h |
1913 | |
2005 | |
1914 | ev_win32.c required on win32 platforms only |
2006 | ev_win32.c required on win32 platforms only |
1915 | |
2007 | |
1916 | 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) |
1917 | 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) |
1918 | 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) |
1919 | 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) |
1920 | 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) |
1921 | |
2013 | |
… | |
… | |
2084 | 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 |
2085 | additional independent event loops. Otherwise there will be no support |
2177 | additional independent event loops. Otherwise there will be no support |
2086 | 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 |
2087 | argument. Instead, all functions act on the single default loop. |
2179 | argument. Instead, all functions act on the single default loop. |
2088 | |
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 | |
2089 | =item EV_PERIODIC_ENABLE |
2198 | =item EV_PERIODIC_ENABLE |
2090 | |
2199 | |
2091 | 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 |
2092 | 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 |
2093 | code. |
2208 | code. |
2094 | |
2209 | |
2095 | =item EV_EMBED_ENABLE |
2210 | =item EV_EMBED_ENABLE |
2096 | |
2211 | |
… | |
… | |
2163 | 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 |
2164 | 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 |
2165 | file. |
2280 | file. |
2166 | |
2281 | |
2167 | 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 |
2168 | that everybody includes and which overrides some autoconf choices: |
2283 | that everybody includes and which overrides some configure choices: |
2169 | |
2284 | |
|
|
2285 | #define EV_MINIMAL 1 |
2170 | #define EV_USE_POLL 0 |
2286 | #define EV_USE_POLL 0 |
2171 | #define EV_MULTIPLICITY 0 |
2287 | #define EV_MULTIPLICITY 0 |
2172 | #define EV_PERIODICS 0 |
2288 | #define EV_PERIODIC_ENABLE 0 |
|
|
2289 | #define EV_STAT_ENABLE 0 |
|
|
2290 | #define EV_FORK_ENABLE 0 |
2173 | #define EV_CONFIG_H <config.h> |
2291 | #define EV_CONFIG_H <config.h> |
|
|
2292 | #define EV_MINPRI 0 |
|
|
2293 | #define EV_MAXPRI 0 |
2174 | |
2294 | |
2175 | #include "ev++.h" |
2295 | #include "ev++.h" |
2176 | |
2296 | |
2177 | 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: |
2178 | |
2298 | |
… | |
… | |
2184 | |
2304 | |
2185 | 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 |
2186 | libev will be explained. For complexity discussions about backends see the |
2306 | libev will be explained. For complexity discussions about backends see the |
2187 | documentation for C<ev_default_init>. |
2307 | documentation for C<ev_default_init>. |
2188 | |
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 | |
2189 | =over 4 |
2315 | =over 4 |
2190 | |
2316 | |
2191 | =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) |
2192 | |
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 | |
2193 | =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) |
2194 | |
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 | |
2195 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2328 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2196 | |
2329 | |
|
|
2330 | These just add the watcher into an array or at the head of a list. |
2197 | =item Stopping check/prepare/idle watchers: O(1) |
2331 | =item Stopping check/prepare/idle watchers: O(1) |
2198 | |
2332 | |
2199 | =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)) |
2200 | |
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 | |
2201 | =item Finding the next timer per loop iteration: O(1) |
2339 | =item Finding the next timer per loop iteration: O(1) |
2202 | |
2340 | |
2203 | =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) |
2204 | |
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 | |
2205 | =item Activating one watcher: O(1) |
2346 | =item Activating one watcher: O(1) |
2206 | |
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 | |
2207 | =back |
2354 | =back |
2208 | |
2355 | |
2209 | |
2356 | |
2210 | =head1 AUTHOR |
2357 | =head1 AUTHOR |
2211 | |
2358 | |