[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 1.74 by root, Sat Dec 8 14:12:08 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
…		…
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
…		…
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 (void (function)(watcher &w, int), 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	See the method-C<set> above for more details.
1789		1856
1790	=item w->set (struct ev_loop *)	1857	=item w->set (struct ev_loop *)
1791		1858
1792	Associates a different C<struct ev_loop> with this watcher. You can only	1859	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).	1860	do this when the watcher is inactive (and not pending either).
1794		1861
1795	=item w->set ([args])	1862	=item w->set ([args])
1796		1863
1797	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1864	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	1865	called at least once. Unlike the C counterpart, an active watcher gets
1799	automatically stopped and restarted.	1866	automatically stopped and restarted when reconfiguring it with this
		1867	method.
1800		1868
1801	=item w->start ()	1869	=item w->start ()
1802		1870
1803	Starts the watcher. Note that there is no C<loop> argument as the	1871	Starts the watcher. Note that there is no C<loop> argument, as the
1804	constructor already takes the loop.	1872	constructor already stores the event loop.
1805		1873
1806	=item w->stop ()	1874	=item w->stop ()
1807		1875
1808	Stops the watcher if it is active. Again, no C<loop> argument.	1876	Stops the watcher if it is active. Again, no C<loop> argument.
1809		1877
…		…
1834		1902
1835	myclass ();	1903	myclass ();
1836	}	1904	}
1837		1905
1838	myclass::myclass (int fd)	1906	myclass::myclass (int fd)
1839	: io (this, &myclass::io_cb),
1840	idle (this, &myclass::idle_cb)
1841	{	1907	{
		1908	io .set <myclass, &myclass::io_cb > (this);
		1909	idle.set <myclass, &myclass::idle_cb> (this);
		1910
1842	io.start (fd, ev::READ);	1911	io.start (fd, ev::READ);
1843	}	1912	}
1844		1913
1845		1914
1846	=head1 MACRO MAGIC	1915	=head1 MACRO MAGIC
…		…
2123	will have the C<struct ev_loop *> as first argument, and you can create	2192	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	2193	additional independent event loops. Otherwise there will be no support
2125	for multiple event loops and there is no first event loop pointer	2194	for multiple event loops and there is no first event loop pointer
2126	argument. Instead, all functions act on the single default loop.	2195	argument. Instead, all functions act on the single default loop.
2127		2196
		2197	=item EV_MINPRI
		2198
		2199	=item EV_MAXPRI
		2200
		2201	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2202	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2203	provide for more priorities by overriding those symbols (usually defined
		2204	to be C<-2> and C<2>, respectively).
		2205
		2206	When doing priority-based operations, libev usually has to linearly search
		2207	all the priorities, so having many of them (hundreds) uses a lot of space
		2208	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2209	fine.
		2210
		2211	If your embedding app does not need any priorities, defining these both to
		2212	C<0> will save some memory and cpu.
		2213
2128	=item EV_PERIODIC_ENABLE	2214	=item EV_PERIODIC_ENABLE
2129		2215
2130	If undefined or defined to be C<1>, then periodic timers are supported. If	2216	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	2217	defined to be C<0>, then they are not. Disabling them saves a few kB of
2132	code.	2218	code.
…		…
2234		2320
2235	In this section the complexities of (many of) the algorithms used inside	2321	In this section the complexities of (many of) the algorithms used inside
2236	libev will be explained. For complexity discussions about backends see the	2322	libev will be explained. For complexity discussions about backends see the
2237	documentation for C<ev_default_init>.	2323	documentation for C<ev_default_init>.
2238		2324
		2325	All of the following are about amortised time: If an array needs to be
		2326	extended, libev needs to realloc and move the whole array, but this
		2327	happens asymptotically never with higher number of elements, so O(1) might
		2328	mean it might do a lengthy realloc operation in rare cases, but on average
		2329	it is much faster and asymptotically approaches constant time.
		2330
2239	=over 4	2331	=over 4
2240		2332
2241	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2333	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2242		2334
		2335	This means that, when you have a watcher that triggers in one hour and
		2336	there are 100 watchers that would trigger before that then inserting will
		2337	have to skip those 100 watchers.
		2338
2243	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2339	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2244		2340
		2341	That means that for changing a timer costs less than removing/adding them
		2342	as only the relative motion in the event queue has to be paid for.
		2343
2245	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2344	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2246		2345
		2346	These just add the watcher into an array or at the head of a list.
2247	=item Stopping check/prepare/idle watchers: O(1)	2347	=item Stopping check/prepare/idle watchers: O(1)
2248		2348
2249	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2349	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2250		2350
		2351	These watchers are stored in lists then need to be walked to find the
		2352	correct watcher to remove. The lists are usually short (you don't usually
		2353	have many watchers waiting for the same fd or signal).
		2354
2251	=item Finding the next timer per loop iteration: O(1)	2355	=item Finding the next timer per loop iteration: O(1)
2252		2356
2253	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2357	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2254		2358
		2359	A change means an I/O watcher gets started or stopped, which requires
		2360	libev to recalculate its status (and possibly tell the kernel).
		2361
2255	=item Activating one watcher: O(1)	2362	=item Activating one watcher: O(1)
2256		2363
		2364	=item Priority handling: O(number_of_priorities)
		2365
		2366	Priorities are implemented by allocating some space for each
		2367	priority. When doing priority-based operations, libev usually has to
		2368	linearly search all the priorities.
		2369
2257	=back	2370	=back
2258		2371
2259		2372
2260	=head1 AUTHOR	2373	=head1 AUTHOR
2261		2374

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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 1.74 by root, Sat Dec 8 14:12:08 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 1.74 by root, Sat Dec 8 14:12:08 2007 UTC