[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.68 by root, Fri Dec 7 18:09:43 2007 UTC vs.
Revision 1.71 by root, Fri Dec 7 20:13:09 2007 UTC

…		…
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
…		…
1740		1744
1741	To use it,	1745	To use it,
1742		1746
1743	#include <ev++.h>	1747	#include <ev++.h>
1744		1748
1745	(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
1746	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
1747	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>.
1748		1753
1749	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
1750	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).
1751		1764
1752	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:
1753		1766
1754	=over 4	1767	=over 4
1755		1768
…		…
1771		1784
1772	All of those classes have these methods:	1785	All of those classes have these methods:
1773		1786
1774	=over 4	1787	=over 4
1775		1788
1776	=item ev::TYPE::TYPE (object , object::method )	1789	=item ev::TYPE::TYPE ()
1777		1790
1778	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1791	=item ev::TYPE::TYPE (struct ev_loop *)
1779		1792
1780	=item ev::TYPE::~TYPE	1793	=item ev::TYPE::~TYPE
1781		1794
1782	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
1783	the event handler callback to call in this class. The constructor calls	1796	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	1797
1785	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
1786	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).
1787		1806
1788	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.
1789		1840
1790	=item w->set (struct ev_loop *)	1841	=item w->set (struct ev_loop *)
1791		1842
1792	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
1793	do this when the watcher is inactive (and not pending either).	1844	do this when the watcher is inactive (and not pending either).
1794		1845
1795	=item w->set ([args])	1846	=item w->set ([args])
1796		1847
1797	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
1798	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
1799	automatically stopped and restarted.	1850	automatically stopped and restarted when reconfiguring it with this
		1851	method.
1800		1852
1801	=item w->start ()	1853	=item w->start ()
1802		1854
1803	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
1804	constructor already takes the loop.	1856	constructor already stores the event loop.
1805		1857
1806	=item w->stop ()	1858	=item w->stop ()
1807		1859
1808	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.
1809		1861
…		…
1834		1886
1835	myclass ();	1887	myclass ();
1836	}	1888	}
1837		1889
1838	myclass::myclass (int fd)	1890	myclass::myclass (int fd)
1839	: io (this, &myclass::io_cb),
1840	idle (this, &myclass::idle_cb)
1841	{	1891	{
		1892	io .set <myclass, &myclass::io_cb > (this);
		1893	idle.set <myclass, &myclass::idle_cb> (this);
		1894
1842	io.start (fd, ev::READ);	1895	io.start (fd, ev::READ);
1843	}	1896	}
1844		1897
1845		1898
1846	=head1 MACRO MAGIC	1899	=head1 MACRO MAGIC
…		…
2123	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
2124	additional independent event loops. Otherwise there will be no support	2177	additional independent event loops. Otherwise there will be no support
2125	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
2126	argument. Instead, all functions act on the single default loop.	2179	argument. Instead, all functions act on the single default loop.
2127		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
2128	=item EV_PERIODIC_ENABLE	2198	=item EV_PERIODIC_ENABLE
2129		2199
2130	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
2131	defined to be C<0>, then they are not. Disabling them saves a few kB of	2201	defined to be C<0>, then they are not. Disabling them saves a few kB of
2132	code.	2202	code.
…		…
2234		2304
2235	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
2236	libev will be explained. For complexity discussions about backends see the	2306	libev will be explained. For complexity discussions about backends see the
2237	documentation for C<ev_default_init>.	2307	documentation for C<ev_default_init>.
2238		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
2239	=over 4	2315	=over 4
2240		2316
2241	=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)
2242		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
2243	=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)
2244		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
2245	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2328	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2246		2329
		2330	These just add the watcher into an array or at the head of a list.
2247	=item Stopping check/prepare/idle watchers: O(1)	2331	=item Stopping check/prepare/idle watchers: O(1)
2248		2332
2249	=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))
2250		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
2251	=item Finding the next timer per loop iteration: O(1)	2339	=item Finding the next timer per loop iteration: O(1)
2252		2340
2253	=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)
2254		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
2255	=item Activating one watcher: O(1)	2346	=item Activating one watcher: O(1)
2256		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
2257	=back	2354	=back
2258		2355
2259		2356
2260	=head1 AUTHOR	2357	=head1 AUTHOR
2261		2358

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Comparing libev/ev.pod (file contents): Revision 1.68 by root, Fri Dec 7 18:09:43 2007 UTC vs. Revision 1.71 by root, Fri Dec 7 20:13:09 2007 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.68 by root, Fri Dec 7 18:09:43 2007 UTC vs.
Revision 1.71 by root, Fri Dec 7 20:13:09 2007 UTC