… | |
… | |
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 | |
… | |
… | |
732 | =item bool ev_is_pending (ev_TYPE *watcher) |
736 | =item bool ev_is_pending (ev_TYPE *watcher) |
733 | |
737 | |
734 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
738 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
735 | events but its callback has not yet been invoked). As long as a watcher |
739 | events but its callback has not yet been invoked). As long as a watcher |
736 | is pending (but not active) you must not call an init function on it (but |
740 | is pending (but not active) you must not call an init function on it (but |
737 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
741 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
738 | libev (e.g. you cnanot C<free ()> it). |
742 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
743 | it). |
739 | |
744 | |
740 | =item callback ev_cb (ev_TYPE *watcher) |
745 | =item callback ev_cb (ev_TYPE *watcher) |
741 | |
746 | |
742 | Returns the callback currently set on the watcher. |
747 | Returns the callback currently set on the watcher. |
743 | |
748 | |
… | |
… | |
762 | watchers on the same event and make sure one is called first. |
767 | watchers on the same event and make sure one is called first. |
763 | |
768 | |
764 | If you need to suppress invocation when higher priority events are pending |
769 | If you need to suppress invocation when higher priority events are pending |
765 | you need to look at C<ev_idle> watchers, which provide this functionality. |
770 | you need to look at C<ev_idle> watchers, which provide this functionality. |
766 | |
771 | |
|
|
772 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
773 | pending. |
|
|
774 | |
767 | The default priority used by watchers when no priority has been set is |
775 | The default priority used by watchers when no priority has been set is |
768 | always C<0>, which is supposed to not be too high and not be too low :). |
776 | always C<0>, which is supposed to not be too high and not be too low :). |
769 | |
777 | |
770 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
778 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
771 | fine, as long as you do not mind that the priority value you query might |
779 | fine, as long as you do not mind that the priority value you query might |
772 | or might not have been adjusted to be within valid range. |
780 | or might not have been adjusted to be within valid range. |
|
|
781 | |
|
|
782 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
783 | |
|
|
784 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
785 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
786 | can deal with that fact. |
|
|
787 | |
|
|
788 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
789 | |
|
|
790 | If the watcher is pending, this function returns clears its pending status |
|
|
791 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
792 | watcher isn't pending it does nothing and returns C<0>. |
773 | |
793 | |
774 | =back |
794 | =back |
775 | |
795 | |
776 | |
796 | |
777 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
797 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
883 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
903 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
884 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
904 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
885 | |
905 | |
886 | If you cannot run the fd in non-blocking mode (for example you should not |
906 | If you cannot run the fd in non-blocking mode (for example you should not |
887 | play around with an Xlib connection), then you have to seperately re-test |
907 | play around with an Xlib connection), then you have to seperately re-test |
888 | wether a file descriptor is really ready with a known-to-be good interface |
908 | whether a file descriptor is really ready with a known-to-be good interface |
889 | such as poll (fortunately in our Xlib example, Xlib already does this on |
909 | such as poll (fortunately in our Xlib example, Xlib already does this on |
890 | its own, so its quite safe to use). |
910 | its own, so its quite safe to use). |
891 | |
911 | |
892 | =over 4 |
912 | =over 4 |
893 | |
913 | |
… | |
… | |
1740 | |
1760 | |
1741 | To use it, |
1761 | To use it, |
1742 | |
1762 | |
1743 | #include <ev++.h> |
1763 | #include <ev++.h> |
1744 | |
1764 | |
1745 | (it is not installed by default). This automatically includes F<ev.h> |
1765 | This automatically includes F<ev.h> and puts all of its definitions (many |
1746 | and puts all of its definitions (many of them macros) into the global |
1766 | of them macros) into the global namespace. All C++ specific things are |
1747 | namespace. All C++ specific things are put into the C<ev> namespace. |
1767 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1768 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1748 | |
1769 | |
1749 | It should support all the same embedding options as F<ev.h>, most notably |
1770 | Care has been taken to keep the overhead low. The only data member the C++ |
1750 | C<EV_MULTIPLICITY>. |
1771 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1772 | that the watcher is associated with (or no additional members at all if |
|
|
1773 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1774 | |
|
|
1775 | Currently, functions, and static and non-static member functions can be |
|
|
1776 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1777 | need one additional pointer for context. If you need support for other |
|
|
1778 | types of functors please contact the author (preferably after implementing |
|
|
1779 | it). |
1751 | |
1780 | |
1752 | Here is a list of things available in the C<ev> namespace: |
1781 | Here is a list of things available in the C<ev> namespace: |
1753 | |
1782 | |
1754 | =over 4 |
1783 | =over 4 |
1755 | |
1784 | |
… | |
… | |
1771 | |
1800 | |
1772 | All of those classes have these methods: |
1801 | All of those classes have these methods: |
1773 | |
1802 | |
1774 | =over 4 |
1803 | =over 4 |
1775 | |
1804 | |
1776 | =item ev::TYPE::TYPE (object *, object::method *) |
1805 | =item ev::TYPE::TYPE () |
1777 | |
1806 | |
1778 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1807 | =item ev::TYPE::TYPE (struct ev_loop *) |
1779 | |
1808 | |
1780 | =item ev::TYPE::~TYPE |
1809 | =item ev::TYPE::~TYPE |
1781 | |
1810 | |
1782 | The constructor takes a pointer to an object and a method pointer to |
1811 | The constructor (optionally) takes an event loop to associate the watcher |
1783 | the event handler callback to call in this class. The constructor calls |
1812 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1784 | C<ev_init> for you, which means you have to call the C<set> method |
1813 | |
1785 | before starting it. If you do not specify a loop then the constructor |
1814 | The constructor calls C<ev_init> for you, which means you have to call the |
1786 | automatically associates the default loop with this watcher. |
1815 | C<set> method before starting it. |
|
|
1816 | |
|
|
1817 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1818 | method to set a callback before you can start the watcher. |
|
|
1819 | |
|
|
1820 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1821 | not allow explicit template arguments for constructors). |
1787 | |
1822 | |
1788 | The destructor automatically stops the watcher if it is active. |
1823 | The destructor automatically stops the watcher if it is active. |
|
|
1824 | |
|
|
1825 | =item w->set<class, &class::method> (object *) |
|
|
1826 | |
|
|
1827 | This method sets the callback method to call. The method has to have a |
|
|
1828 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1829 | first argument and the C<revents> as second. The object must be given as |
|
|
1830 | parameter and is stored in the C<data> member of the watcher. |
|
|
1831 | |
|
|
1832 | This method synthesizes efficient thunking code to call your method from |
|
|
1833 | the C callback that libev requires. If your compiler can inline your |
|
|
1834 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1835 | your compiler is good :), then the method will be fully inlined into the |
|
|
1836 | thunking function, making it as fast as a direct C callback. |
|
|
1837 | |
|
|
1838 | Example: simple class declaration and watcher initialisation |
|
|
1839 | |
|
|
1840 | struct myclass |
|
|
1841 | { |
|
|
1842 | void io_cb (ev::io &w, int revents) { } |
|
|
1843 | } |
|
|
1844 | |
|
|
1845 | myclass obj; |
|
|
1846 | ev::io iow; |
|
|
1847 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1848 | |
|
|
1849 | =item w->set<function> (void *data = 0) |
|
|
1850 | |
|
|
1851 | Also sets a callback, but uses a static method or plain function as |
|
|
1852 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
1853 | C<data> member and is free for you to use. |
|
|
1854 | |
|
|
1855 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
1856 | |
|
|
1857 | See the method-C<set> above for more details. |
|
|
1858 | |
|
|
1859 | Example: |
|
|
1860 | |
|
|
1861 | static void io_cb (ev::io &w, int revents) { } |
|
|
1862 | iow.set <io_cb> (); |
1789 | |
1863 | |
1790 | =item w->set (struct ev_loop *) |
1864 | =item w->set (struct ev_loop *) |
1791 | |
1865 | |
1792 | Associates a different C<struct ev_loop> with this watcher. You can only |
1866 | Associates a different C<struct ev_loop> with this watcher. You can only |
1793 | do this when the watcher is inactive (and not pending either). |
1867 | do this when the watcher is inactive (and not pending either). |
1794 | |
1868 | |
1795 | =item w->set ([args]) |
1869 | =item w->set ([args]) |
1796 | |
1870 | |
1797 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1871 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1798 | called at least once. Unlike the C counterpart, an active watcher gets |
1872 | called at least once. Unlike the C counterpart, an active watcher gets |
1799 | automatically stopped and restarted. |
1873 | automatically stopped and restarted when reconfiguring it with this |
|
|
1874 | method. |
1800 | |
1875 | |
1801 | =item w->start () |
1876 | =item w->start () |
1802 | |
1877 | |
1803 | Starts the watcher. Note that there is no C<loop> argument as the |
1878 | Starts the watcher. Note that there is no C<loop> argument, as the |
1804 | constructor already takes the loop. |
1879 | constructor already stores the event loop. |
1805 | |
1880 | |
1806 | =item w->stop () |
1881 | =item w->stop () |
1807 | |
1882 | |
1808 | Stops the watcher if it is active. Again, no C<loop> argument. |
1883 | Stops the watcher if it is active. Again, no C<loop> argument. |
1809 | |
1884 | |
… | |
… | |
1834 | |
1909 | |
1835 | myclass (); |
1910 | myclass (); |
1836 | } |
1911 | } |
1837 | |
1912 | |
1838 | myclass::myclass (int fd) |
1913 | myclass::myclass (int fd) |
1839 | : io (this, &myclass::io_cb), |
|
|
1840 | idle (this, &myclass::idle_cb) |
|
|
1841 | { |
1914 | { |
|
|
1915 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1916 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1917 | |
1842 | io.start (fd, ev::READ); |
1918 | io.start (fd, ev::READ); |
1843 | } |
1919 | } |
1844 | |
1920 | |
1845 | |
1921 | |
1846 | =head1 MACRO MAGIC |
1922 | =head1 MACRO MAGIC |
1847 | |
1923 | |
1848 | Libev can be compiled with a variety of options, the most fundemantal is |
1924 | Libev can be compiled with a variety of options, the most fundemantal is |
1849 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
1925 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
1850 | callbacks have an initial C<struct ev_loop *> argument. |
1926 | callbacks have an initial C<struct ev_loop *> argument. |
1851 | |
1927 | |
1852 | To make it easier to write programs that cope with either variant, the |
1928 | To make it easier to write programs that cope with either variant, the |
1853 | following macros are defined: |
1929 | following macros are defined: |
1854 | |
1930 | |
… | |
… | |
1888 | loop, if multiple loops are supported ("ev loop default"). |
1964 | loop, if multiple loops are supported ("ev loop default"). |
1889 | |
1965 | |
1890 | =back |
1966 | =back |
1891 | |
1967 | |
1892 | Example: Declare and initialise a check watcher, utilising the above |
1968 | Example: Declare and initialise a check watcher, utilising the above |
1893 | macros so it will work regardless of wether multiple loops are supported |
1969 | macros so it will work regardless of whether multiple loops are supported |
1894 | or not. |
1970 | or not. |
1895 | |
1971 | |
1896 | static void |
1972 | static void |
1897 | check_cb (EV_P_ ev_timer *w, int revents) |
1973 | check_cb (EV_P_ ev_timer *w, int revents) |
1898 | { |
1974 | { |
… | |
… | |
2123 | will have the C<struct ev_loop *> as first argument, and you can create |
2199 | will have the C<struct ev_loop *> as first argument, and you can create |
2124 | additional independent event loops. Otherwise there will be no support |
2200 | additional independent event loops. Otherwise there will be no support |
2125 | for multiple event loops and there is no first event loop pointer |
2201 | for multiple event loops and there is no first event loop pointer |
2126 | argument. Instead, all functions act on the single default loop. |
2202 | argument. Instead, all functions act on the single default loop. |
2127 | |
2203 | |
|
|
2204 | =item EV_MINPRI |
|
|
2205 | |
|
|
2206 | =item EV_MAXPRI |
|
|
2207 | |
|
|
2208 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2209 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2210 | provide for more priorities by overriding those symbols (usually defined |
|
|
2211 | to be C<-2> and C<2>, respectively). |
|
|
2212 | |
|
|
2213 | When doing priority-based operations, libev usually has to linearly search |
|
|
2214 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2215 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2216 | fine. |
|
|
2217 | |
|
|
2218 | If your embedding app does not need any priorities, defining these both to |
|
|
2219 | C<0> will save some memory and cpu. |
|
|
2220 | |
2128 | =item EV_PERIODIC_ENABLE |
2221 | =item EV_PERIODIC_ENABLE |
2129 | |
2222 | |
2130 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2223 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2131 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2224 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2132 | code. |
2225 | code. |
… | |
… | |
2234 | |
2327 | |
2235 | In this section the complexities of (many of) the algorithms used inside |
2328 | In this section the complexities of (many of) the algorithms used inside |
2236 | libev will be explained. For complexity discussions about backends see the |
2329 | libev will be explained. For complexity discussions about backends see the |
2237 | documentation for C<ev_default_init>. |
2330 | documentation for C<ev_default_init>. |
2238 | |
2331 | |
|
|
2332 | All of the following are about amortised time: If an array needs to be |
|
|
2333 | extended, libev needs to realloc and move the whole array, but this |
|
|
2334 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2335 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2336 | it is much faster and asymptotically approaches constant time. |
|
|
2337 | |
2239 | =over 4 |
2338 | =over 4 |
2240 | |
2339 | |
2241 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2340 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2242 | |
2341 | |
|
|
2342 | This means that, when you have a watcher that triggers in one hour and |
|
|
2343 | there are 100 watchers that would trigger before that then inserting will |
|
|
2344 | have to skip those 100 watchers. |
|
|
2345 | |
2243 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2346 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2244 | |
2347 | |
|
|
2348 | That means that for changing a timer costs less than removing/adding them |
|
|
2349 | as only the relative motion in the event queue has to be paid for. |
|
|
2350 | |
2245 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2351 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2246 | |
2352 | |
|
|
2353 | These just add the watcher into an array or at the head of a list. |
2247 | =item Stopping check/prepare/idle watchers: O(1) |
2354 | =item Stopping check/prepare/idle watchers: O(1) |
2248 | |
2355 | |
2249 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2356 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2250 | |
2357 | |
|
|
2358 | These watchers are stored in lists then need to be walked to find the |
|
|
2359 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2360 | have many watchers waiting for the same fd or signal). |
|
|
2361 | |
2251 | =item Finding the next timer per loop iteration: O(1) |
2362 | =item Finding the next timer per loop iteration: O(1) |
2252 | |
2363 | |
2253 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2364 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2254 | |
2365 | |
|
|
2366 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2367 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2368 | |
2255 | =item Activating one watcher: O(1) |
2369 | =item Activating one watcher: O(1) |
2256 | |
2370 | |
|
|
2371 | =item Priority handling: O(number_of_priorities) |
|
|
2372 | |
|
|
2373 | Priorities are implemented by allocating some space for each |
|
|
2374 | priority. When doing priority-based operations, libev usually has to |
|
|
2375 | linearly search all the priorities. |
|
|
2376 | |
2257 | =back |
2377 | =back |
2258 | |
2378 | |
2259 | |
2379 | |
2260 | =head1 AUTHOR |
2380 | =head1 AUTHOR |
2261 | |
2381 | |