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

Comparing libev/ev.pod (file contents):
Revision 1.183 by root, Tue Sep 23 08:37:38 2008 UTC vs.
Revision 1.197 by root, Tue Oct 21 20:52:30 2008 UTC

…		…
214	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	214	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
215	recommended ones.	215	recommended ones.
216		216
217	See the description of C<ev_embed> watchers for more info.	217	See the description of C<ev_embed> watchers for more info.
218		218
219	=item ev_set_allocator (void (cb)(void *ptr, long size))	219	=item ev_set_allocator (void (cb)(void *ptr, long size)) [NOT REENTRANT]
220		220
221	Sets the allocation function to use (the prototype is similar - the	221	Sets the allocation function to use (the prototype is similar - the
222	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	222	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
223	used to allocate and free memory (no surprises here). If it returns zero	223	used to allocate and free memory (no surprises here). If it returns zero
224	when memory needs to be allocated (C<size != 0>), the library might abort	224	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
250	}	250	}
251		251
252	...	252	...
253	ev_set_allocator (persistent_realloc);	253	ev_set_allocator (persistent_realloc);
254		254
255	=item ev_set_syserr_cb (void (cb)(const char msg));	255	=item ev_set_syserr_cb (void (cb)(const char msg)); [NOT REENTRANT]
256		256
257	Set the callback function to call on a retryable system call error (such	257	Set the callback function to call on a retryable system call error (such
258	as failed select, poll, epoll_wait). The message is a printable string	258	as failed select, poll, epoll_wait). The message is a printable string
259	indicating the system call or subsystem causing the problem. If this	259	indicating the system call or subsystem causing the problem. If this
260	callback is set, then libev will expect it to remedy the situation, no	260	callback is set, then libev will expect it to remedy the situation, no
…		…
685	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	685	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
686	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	686	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
687		687
688	This "unloop state" will be cleared when entering C<ev_loop> again.	688	This "unloop state" will be cleared when entering C<ev_loop> again.
689		689
		690	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.
		691
690	=item ev_ref (loop)	692	=item ev_ref (loop)
691		693
692	=item ev_unref (loop)	694	=item ev_unref (loop)
693		695
694	Ref/unref can be used to add or remove a reference count on the event	696	Ref/unref can be used to add or remove a reference count on the event
…		…
892	=item C<EV_ERROR>	894	=item C<EV_ERROR>
893		895
894	An unspecified error has occurred, the watcher has been stopped. This might	896	An unspecified error has occurred, the watcher has been stopped. This might
895	happen because the watcher could not be properly started because libev	897	happen because the watcher could not be properly started because libev
896	ran out of memory, a file descriptor was found to be closed or any other	898	ran out of memory, a file descriptor was found to be closed or any other
		899	problem. Libev considers these application bugs.
		900
897	problem. You best act on it by reporting the problem and somehow coping	901	You best act on it by reporting the problem and somehow coping with the
898	with the watcher being stopped.	902	watcher being stopped. Note that well-written programs should not receive
		903	an error ever, so when your watcher receives it, this usually indicates a
		904	bug in your program.
899		905
900	Libev will usually signal a few "dummy" events together with an error, for	906	Libev will usually signal a few "dummy" events together with an error, for
901	example it might indicate that a fd is readable or writable, and if your	907	example it might indicate that a fd is readable or writable, and if your
902	callbacks is well-written it can just attempt the operation and cope with	908	callbacks is well-written it can just attempt the operation and cope with
903	the error from read() or write(). This will not work in multi-threaded	909	the error from read() or write(). This will not work in multi-threaded
…		…
967		973
968	ev_io_start (EV_DEFAULT_UC, &w);	974	ev_io_start (EV_DEFAULT_UC, &w);
969		975
970	=item C<ev_TYPE_stop> (loop , ev_TYPE watcher)	976	=item C<ev_TYPE_stop> (loop , ev_TYPE watcher)
971		977
972	Stops the given watcher again (if active) and clears the pending	978	Stops the given watcher if active, and clears the pending status (whether
		979	the watcher was active or not).
		980
973	status. It is possible that stopped watchers are pending (for example,	981	It is possible that stopped watchers are pending - for example,
974	non-repeating timers are being stopped when they become pending), but	982	non-repeating timers are being stopped when they become pending - but
975	C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If	983	calling C<ev_TYPE_stop> ensures that the watcher is neither active nor
976	you want to free or reuse the memory used by the watcher it is therefore a	984	pending. If you want to free or reuse the memory used by the watcher it is
977	good idea to always call its C<ev_TYPE_stop> function.	985	therefore a good idea to always call its C<ev_TYPE_stop> function.
978		986
979	=item bool ev_is_active (ev_TYPE *watcher)	987	=item bool ev_is_active (ev_TYPE *watcher)
980		988
981	Returns a true value iff the watcher is active (i.e. it has been started	989	Returns a true value iff the watcher is active (i.e. it has been started
982	and not yet been stopped). As long as a watcher is active you must not modify	990	and not yet been stopped). As long as a watcher is active you must not modify
…		…
1625		1633
1626	=back	1634	=back
1627		1635
1628	=head3 Examples	1636	=head3 Examples
1629		1637
1630	Example: Try to exit cleanly on SIGINT and SIGTERM.	1638	Example: Try to exit cleanly on SIGINT.
1631		1639
1632	static void	1640	static void
1633	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1641	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1634	{	1642	{
1635	ev_unloop (loop, EVUNLOOP_ALL);	1643	ev_unloop (loop, EVUNLOOP_ALL);
1636	}	1644	}
1637		1645
1638	struct ev_signal signal_watcher;	1646	struct ev_signal signal_watcher;
1639	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1647	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1640	ev_signal_start (loop, &sigint_cb);	1648	ev_signal_start (loop, &signal_watcher);
1641		1649
1642		1650
1643	=head2 C<ev_child> - watch out for process status changes	1651	=head2 C<ev_child> - watch out for process status changes
1644		1652
1645	Child watchers trigger when your process receives a SIGCHLD in response to	1653	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1792	to exchange stat structures with application programs compiled using the	1800	to exchange stat structures with application programs compiled using the
1793	default compilation environment.	1801	default compilation environment.
1794		1802
1795	=head3 Inotify and Kqueue	1803	=head3 Inotify and Kqueue
1796		1804
1797	When C<inotify (7)> support has been compiled into libev (generally only	1805	When C<inotify (7)> support has been compiled into libev (generally
		1806	only available with Linux 2.6.25 or above due to bugs in earlier
1798	available with Linux) and present at runtime, it will be used to speed up	1807	implementations) and present at runtime, it will be used to speed up
1799	change detection where possible. The inotify descriptor will be created lazily	1808	change detection where possible. The inotify descriptor will be created
1800	when the first C<ev_stat> watcher is being started.	1809	lazily when the first C<ev_stat> watcher is being started.
1801		1810
1802	Inotify presence does not change the semantics of C<ev_stat> watchers	1811	Inotify presence does not change the semantics of C<ev_stat> watchers
1803	except that changes might be detected earlier, and in some cases, to avoid	1812	except that changes might be detected earlier, and in some cases, to avoid
1804	making regular C<stat> calls. Even in the presence of inotify support	1813	making regular C<stat> calls. Even in the presence of inotify support
1805	there are many cases where libev has to resort to regular C<stat> polling,	1814	there are many cases where libev has to resort to regular C<stat> polling,
…		…
2233	when you fork, you not only have to call C<ev_loop_fork> on both loops,	2242	when you fork, you not only have to call C<ev_loop_fork> on both loops,
2234	but you will also have to stop and restart any C<ev_embed> watchers	2243	but you will also have to stop and restart any C<ev_embed> watchers
2235	yourself - but you can use a fork watcher to handle this automatically,	2244	yourself - but you can use a fork watcher to handle this automatically,
2236	and future versions of libev might do just that.	2245	and future versions of libev might do just that.
2237		2246
2238	Unfortunately, not all backends are embeddable, only the ones returned by	2247	Unfortunately, not all backends are embeddable: only the ones returned by
2239	C<ev_embeddable_backends> are, which, unfortunately, does not include any	2248	C<ev_embeddable_backends> are, which, unfortunately, does not include any
2240	portable one.	2249	portable one.
2241		2250
2242	So when you want to use this feature you will always have to be prepared	2251	So when you want to use this feature you will always have to be prepared
2243	that you cannot get an embeddable loop. The recommended way to get around	2252	that you cannot get an embeddable loop. The recommended way to get around
2244	this is to have a separate variables for your embeddable loop, try to	2253	this is to have a separate variables for your embeddable loop, try to
2245	create it, and if that fails, use the normal loop for everything.	2254	create it, and if that fails, use the normal loop for everything.
		2255
		2256	=head3 C<ev_embed> and fork
		2257
		2258	While the C<ev_embed> watcher is running, forks in the embedding loop will
		2259	automatically be applied to the embedded loop as well, so no special
		2260	fork handling is required in that case. When the watcher is not running,
		2261	however, it is still the task of the libev user to call C<ev_loop_fork ()>
		2262	as applicable.
2246		2263
2247	=head3 Watcher-Specific Functions and Data Members	2264	=head3 Watcher-Specific Functions and Data Members
2248		2265
2249	=over 4	2266	=over 4
2250		2267
…		…
2368	is that the author does not know of a simple (or any) algorithm for a	2385	is that the author does not know of a simple (or any) algorithm for a
2369	multiple-writer-single-reader queue that works in all cases and doesn't	2386	multiple-writer-single-reader queue that works in all cases and doesn't
2370	need elaborate support such as pthreads.	2387	need elaborate support such as pthreads.
2371		2388
2372	That means that if you want to queue data, you have to provide your own	2389	That means that if you want to queue data, you have to provide your own
2373	queue. But at least I can tell you would implement locking around your	2390	queue. But at least I can tell you how to implement locking around your
2374	queue:	2391	queue:
2375		2392
2376	=over 4	2393	=over 4
2377		2394
2378	=item queueing from a signal handler context	2395	=item queueing from a signal handler context
2379		2396
2380	To implement race-free queueing, you simply add to the queue in the signal	2397	To implement race-free queueing, you simply add to the queue in the signal
2381	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2398	handler but you block the signal handler in the watcher callback. Here is
2382	some fictitious SIGUSR1 handler:	2399	an example that does that for some fictitious SIGUSR1 handler:
2383		2400
2384	static ev_async mysig;	2401	static ev_async mysig;
2385		2402
2386	static void	2403	static void
2387	sigusr1_handler (void)	2404	sigusr1_handler (void)
…		…
2454		2471
2455	=item ev_async_init (ev_async *, callback)	2472	=item ev_async_init (ev_async *, callback)
2456		2473
2457	Initialises and configures the async watcher - it has no parameters of any	2474	Initialises and configures the async watcher - it has no parameters of any
2458	kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless,	2475	kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless,
2459	believe me.	2476	trust me.
2460		2477
2461	=item ev_async_send (loop, ev_async *)	2478	=item ev_async_send (loop, ev_async *)
2462		2479
2463	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2480	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2464	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2481	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2465	C<ev_feed_event>, this call is safe to do in other threads, signal or	2482	C<ev_feed_event>, this call is safe to do from other threads, signal or
2466	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding	2483	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2467	section below on what exactly this means).	2484	section below on what exactly this means).
2468		2485
2469	This call incurs the overhead of a system call only once per loop iteration,	2486	This call incurs the overhead of a system call only once per loop iteration,
2470	so while the overhead might be noticeable, it doesn't apply to repeated	2487	so while the overhead might be noticeable, it doesn't apply to repeated
…		…
2494	=over 4	2511	=over 4
2495		2512
2496	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)	2513	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)
2497		2514
2498	This function combines a simple timer and an I/O watcher, calls your	2515	This function combines a simple timer and an I/O watcher, calls your
2499	callback on whichever event happens first and automatically stop both	2516	callback on whichever event happens first and automatically stops both
2500	watchers. This is useful if you want to wait for a single event on an fd	2517	watchers. This is useful if you want to wait for a single event on an fd
2501	or timeout without having to allocate/configure/start/stop/free one or	2518	or timeout without having to allocate/configure/start/stop/free one or
2502	more watchers yourself.	2519	more watchers yourself.
2503		2520
2504	If C<fd> is less than 0, then no I/O watcher will be started and events	2521	If C<fd> is less than 0, then no I/O watcher will be started and the
2505	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2522	C<events> argument is being ignored. Otherwise, an C<ev_io> watcher for
2506	C<events> set will be created and started.	2523	the given C<fd> and C<events> set will be created and started.
2507		2524
2508	If C<timeout> is less than 0, then no timeout watcher will be	2525	If C<timeout> is less than 0, then no timeout watcher will be
2509	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2526	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2510	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2527	repeat = 0) will be started. C<0> is a valid timeout.
2511	dubious value.
2512		2528
2513	The callback has the type C<void (cb)(int revents, void arg)> and gets	2529	The callback has the type C<void (cb)(int revents, void arg)> and gets
2514	passed an C<revents> set like normal event callbacks (a combination of	2530	passed an C<revents> set like normal event callbacks (a combination of
2515	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2531	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2516	value passed to C<ev_once>:	2532	value passed to C<ev_once>. Note that it is possible to receive I<both>
		2533	a timeout and an io event at the same time - you probably should give io
		2534	events precedence.
		2535
		2536	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
2517		2537
2518	static void stdin_ready (int revents, void *arg)	2538	static void stdin_ready (int revents, void *arg)
2519	{	2539	{
		2540	if (revents & EV_READ)
		2541	/* stdin might have data for us, joy! */;
2520	if (revents & EV_TIMEOUT)	2542	else if (revents & EV_TIMEOUT)
2521	/* doh, nothing entered */;	2543	/* doh, nothing entered */;
2522	else if (revents & EV_READ)
2523	/* stdin might have data for us, joy! */;
2524	}	2544	}
2525		2545
2526	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2546	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2527		2547
2528	=item ev_feed_event (ev_loop , watcher , int revents)	2548	=item ev_feed_event (ev_loop , watcher , int revents)
…		…
2676		2696
2677	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.	2697	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
2678		2698
2679	See the method-C<set> above for more details.	2699	See the method-C<set> above for more details.
2680		2700
2681	Example:	2701	Example: Use a plain function as callback.
2682		2702
2683	static void io_cb (ev::io &w, int revents) { }	2703	static void io_cb (ev::io &w, int revents) { }
2684	iow.set <io_cb> ();	2704	iow.set <io_cb> ();
2685		2705
2686	=item w->set (struct ev_loop *)	2706	=item w->set (struct ev_loop *)
…		…
2724	Example: Define a class with an IO and idle watcher, start one of them in	2744	Example: Define a class with an IO and idle watcher, start one of them in
2725	the constructor.	2745	the constructor.
2726		2746
2727	class myclass	2747	class myclass
2728	{	2748	{
2729	ev::io io; void io_cb (ev::io &w, int revents);	2749	ev::io io ; void io_cb (ev::io &w, int revents);
2730	ev:idle idle void idle_cb (ev::idle &w, int revents);	2750	ev::idle idle; void idle_cb (ev::idle &w, int revents);
2731		2751
2732	myclass (int fd)	2752	myclass (int fd)
2733	{	2753	{
2734	io .set <myclass, &myclass::io_cb > (this);	2754	io .set <myclass, &myclass::io_cb > (this);
2735	idle.set <myclass, &myclass::idle_cb> (this);	2755	idle.set <myclass, &myclass::idle_cb> (this);
…		…
2751	=item Perl	2771	=item Perl
2752		2772
2753	The EV module implements the full libev API and is actually used to test	2773	The EV module implements the full libev API and is actually used to test
2754	libev. EV is developed together with libev. Apart from the EV core module,	2774	libev. EV is developed together with libev. Apart from the EV core module,
2755	there are additional modules that implement libev-compatible interfaces	2775	there are additional modules that implement libev-compatible interfaces
2756	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2776	to C<libadns> (C<EV::ADNS>, but C<AnyEvent::DNS> is preferred nowadays),
2757	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2777	C<Net::SNMP> (C<Net::SNMP::EV>) and the C<libglib> event core (C<Glib::EV>
		2778	and C<EV::Glib>).
2758		2779
2759	It can be found and installed via CPAN, its homepage is at	2780	It can be found and installed via CPAN, its homepage is at
2760	L<http://software.schmorp.de/pkg/EV>.	2781	L<http://software.schmorp.de/pkg/EV>.
2761		2782
2762	=item Python	2783	=item Python
…		…
2941		2962
2942	=head2 PREPROCESSOR SYMBOLS/MACROS	2963	=head2 PREPROCESSOR SYMBOLS/MACROS
2943		2964
2944	Libev can be configured via a variety of preprocessor symbols you have to	2965	Libev can be configured via a variety of preprocessor symbols you have to
2945	define before including any of its files. The default in the absence of	2966	define before including any of its files. The default in the absence of
2946	autoconf is noted for every option.	2967	autoconf is documented for every option.
2947		2968
2948	=over 4	2969	=over 4
2949		2970
2950	=item EV_STANDALONE	2971	=item EV_STANDALONE
2951		2972
…		…
3121	When doing priority-based operations, libev usually has to linearly search	3142	When doing priority-based operations, libev usually has to linearly search
3122	all the priorities, so having many of them (hundreds) uses a lot of space	3143	all the priorities, so having many of them (hundreds) uses a lot of space
3123	and time, so using the defaults of five priorities (-2 .. +2) is usually	3144	and time, so using the defaults of five priorities (-2 .. +2) is usually
3124	fine.	3145	fine.
3125		3146
3126	If your embedding application does not need any priorities, defining these both to	3147	If your embedding application does not need any priorities, defining these
3127	C<0> will save some memory and CPU.	3148	both to C<0> will save some memory and CPU.
3128		3149
3129	=item EV_PERIODIC_ENABLE	3150	=item EV_PERIODIC_ENABLE
3130		3151
3131	If undefined or defined to be C<1>, then periodic timers are supported. If	3152	If undefined or defined to be C<1>, then periodic timers are supported. If
3132	defined to be C<0>, then they are not. Disabling them saves a few kB of	3153	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
3139	code.	3160	code.
3140		3161
3141	=item EV_EMBED_ENABLE	3162	=item EV_EMBED_ENABLE
3142		3163
3143	If undefined or defined to be C<1>, then embed watchers are supported. If	3164	If undefined or defined to be C<1>, then embed watchers are supported. If
3144	defined to be C<0>, then they are not.	3165	defined to be C<0>, then they are not. Embed watchers rely on most other
		3166	watcher types, which therefore must not be disabled.
3145		3167
3146	=item EV_STAT_ENABLE	3168	=item EV_STAT_ENABLE
3147		3169
3148	If undefined or defined to be C<1>, then stat watchers are supported. If	3170	If undefined or defined to be C<1>, then stat watchers are supported. If
3149	defined to be C<0>, then they are not.	3171	defined to be C<0>, then they are not.
…		…
3181	two).	3203	two).
3182		3204
3183	=item EV_USE_4HEAP	3205	=item EV_USE_4HEAP
3184		3206
3185	Heaps are not very cache-efficient. To improve the cache-efficiency of the	3207	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3186	timer and periodics heap, libev uses a 4-heap when this symbol is defined	3208	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3187	to C<1>. The 4-heap uses more complicated (longer) code but has	3209	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3188	noticeably faster performance with many (thousands) of watchers.	3210	faster performance with many (thousands) of watchers.
3189		3211
3190	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	3212	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
3191	(disabled).	3213	(disabled).
3192		3214
3193	=item EV_HEAP_CACHE_AT	3215	=item EV_HEAP_CACHE_AT
3194		3216
3195	Heaps are not very cache-efficient. To improve the cache-efficiency of the	3217	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3196	timer and periodics heap, libev can cache the timestamp (I<at>) within	3218	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3197	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	3219	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3198	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	3220	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3199	but avoids random read accesses on heap changes. This improves performance	3221	but avoids random read accesses on heap changes. This improves performance
3200	noticeably with with many (hundreds) of watchers.	3222	noticeably with many (hundreds) of watchers.
3201		3223
3202	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	3224	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
3203	(disabled).	3225	(disabled).
3204		3226
3205	=item EV_VERIFY	3227	=item EV_VERIFY
…		…
3211	called once per loop, which can slow down libev. If set to C<3>, then the	3233	called once per loop, which can slow down libev. If set to C<3>, then the
3212	verification code will be called very frequently, which will slow down	3234	verification code will be called very frequently, which will slow down
3213	libev considerably.	3235	libev considerably.
3214		3236
3215	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	3237	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
3216	C<0.>	3238	C<0>.
3217		3239
3218	=item EV_COMMON	3240	=item EV_COMMON
3219		3241
3220	By default, all watchers have a C<void *data> member. By redefining	3242	By default, all watchers have a C<void *data> member. By redefining
3221	this macro to a something else you can include more and other types of	3243	this macro to a something else you can include more and other types of
…		…
3238	and the way callbacks are invoked and set. Must expand to a struct member	3260	and the way callbacks are invoked and set. Must expand to a struct member
3239	definition and a statement, respectively. See the F<ev.h> header file for	3261	definition and a statement, respectively. See the F<ev.h> header file for
3240	their default definitions. One possible use for overriding these is to	3262	their default definitions. One possible use for overriding these is to
3241	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3263	avoid the C<struct ev_loop *> as first argument in all cases, or to use
3242	method calls instead of plain function calls in C++.	3264	method calls instead of plain function calls in C++.
		3265
		3266	=back
3243		3267
3244	=head2 EXPORTED API SYMBOLS	3268	=head2 EXPORTED API SYMBOLS
3245		3269
3246	If you need to re-export the API (e.g. via a DLL) and you need a list of	3270	If you need to re-export the API (e.g. via a DLL) and you need a list of
3247	exported symbols, you can use the provided F<Symbol.*> files which list	3271	exported symbols, you can use the provided F<Symbol.*> files which list
…		…
3294	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3318	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3295		3319
3296	#include "ev_cpp.h"	3320	#include "ev_cpp.h"
3297	#include "ev.c"	3321	#include "ev.c"
3298		3322
		3323	=head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES
3299		3324
3300	=head1 THREADS AND COROUTINES	3325	=head2 THREADS AND COROUTINES
3301		3326
3302	=head2 THREADS	3327	=head3 THREADS
3303		3328
3304	Libev itself is thread-safe (unless the opposite is specifically	3329	All libev functions are reentrant and thread-safe unless explicitly
3305	documented for a function), but it uses no locking itself. This means that	3330	documented otherwise, but libev implements no locking itself. This means
3306	you can use as many loops as you want in parallel, as long as only one	3331	that you can use as many loops as you want in parallel, as long as there
3307	thread ever calls into one libev function with the same loop parameter:	3332	are no concurrent calls into any libev function with the same loop
		3333	parameter (C<ev_default_*> calls have an implicit default loop parameter,
3308	libev guarentees that different event loops share no data structures that	3334	of course): libev guarantees that different event loops share no data
3309	need locking.	3335	structures that need any locking.
3310		3336
3311	Or to put it differently: calls with different loop parameters can be done	3337	Or to put it differently: calls with different loop parameters can be done
3312	concurrently from multiple threads, calls with the same loop parameter	3338	concurrently from multiple threads, calls with the same loop parameter
3313	must be done serially (but can be done from different threads, as long as	3339	must be done serially (but can be done from different threads, as long as
3314	only one thread ever is inside a call at any point in time, e.g. by using	3340	only one thread ever is inside a call at any point in time, e.g. by using
3315	a mutex per loop).	3341	a mutex per loop).
3316		3342
3317	Specifically to support threads (and signal handlers), libev implements	3343	Specifically to support threads (and signal handlers), libev implements
3318	so-called C<ev_async> watchers, which allow some limited form of	3344	so-called C<ev_async> watchers, which allow some limited form of
3319	concurrency on the same event loop.	3345	concurrency on the same event loop, namely waking it up "from the
		3346	outside".
3320		3347
3321	If you want to know which design (one loop, locking, or multiple loops	3348	If you want to know which design (one loop, locking, or multiple loops
3322	without or something else still) is best for your problem, then I cannot	3349	without or something else still) is best for your problem, then I cannot
3323	help you. I can give some generic advice however:	3350	help you, but here is some generic advice:
3324		3351
3325	=over 4	3352	=over 4
3326		3353
3327	=item * most applications have a main thread: use the default libev loop	3354	=item * most applications have a main thread: use the default libev loop
3328	in that thread, or create a separate thread running only the default loop.	3355	in that thread, or create a separate thread running only the default loop.
…		…
3352	default loop and triggering an C<ev_async> watcher from the default loop	3379	default loop and triggering an C<ev_async> watcher from the default loop
3353	watcher callback into the event loop interested in the signal.	3380	watcher callback into the event loop interested in the signal.
3354		3381
3355	=back	3382	=back
3356		3383
3357	=head2 COROUTINES	3384	=head3 COROUTINES
3358		3385
3359	Libev is much more accommodating to coroutines ("cooperative threads"):	3386	Libev is very accommodating to coroutines ("cooperative threads"):
3360	libev fully supports nesting calls to it's functions from different	3387	libev fully supports nesting calls to its functions from different
3361	coroutines (e.g. you can call C<ev_loop> on the same loop from two	3388	coroutines (e.g. you can call C<ev_loop> on the same loop from two
3362	different coroutines and switch freely between both coroutines running the	3389	different coroutines, and switch freely between both coroutines running the
3363	loop, as long as you don't confuse yourself). The only exception is that	3390	loop, as long as you don't confuse yourself). The only exception is that
3364	you must not do this from C<ev_periodic> reschedule callbacks.	3391	you must not do this from C<ev_periodic> reschedule callbacks.
3365		3392
3366	Care has been taken to ensure that libev does not keep local state inside	3393	Care has been taken to ensure that libev does not keep local state inside
3367	C<ev_loop>, and other calls do not usually allow coroutine switches.	3394	C<ev_loop>, and other calls do not usually allow for coroutine switches as
		3395	they do not clal any callbacks.
3368		3396
		3397	=head2 COMPILER WARNINGS
3369		3398
3370	=head1 COMPLEXITIES	3399	Depending on your compiler and compiler settings, you might get no or a
		3400	lot of warnings when compiling libev code. Some people are apparently
		3401	scared by this.
3371		3402
3372	In this section the complexities of (many of) the algorithms used inside	3403	However, these are unavoidable for many reasons. For one, each compiler
3373	libev will be explained. For complexity discussions about backends see the	3404	has different warnings, and each user has different tastes regarding
3374	documentation for C<ev_default_init>.	3405	warning options. "Warn-free" code therefore cannot be a goal except when
		3406	targeting a specific compiler and compiler-version.
3375		3407
3376	All of the following are about amortised time: If an array needs to be	3408	Another reason is that some compiler warnings require elaborate
3377	extended, libev needs to realloc and move the whole array, but this	3409	workarounds, or other changes to the code that make it less clear and less
3378	happens asymptotically never with higher number of elements, so O(1) might	3410	maintainable.
3379	mean it might do a lengthy realloc operation in rare cases, but on average
3380	it is much faster and asymptotically approaches constant time.
3381		3411
3382	=over 4	3412	And of course, some compiler warnings are just plain stupid, or simply
		3413	wrong (because they don't actually warn about the condition their message
		3414	seems to warn about). For example, certain older gcc versions had some
		3415	warnings that resulted an extreme number of false positives. These have
		3416	been fixed, but some people still insist on making code warn-free with
		3417	such buggy versions.
3383		3418
3384	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	3419	While libev is written to generate as few warnings as possible,
		3420	"warn-free" code is not a goal, and it is recommended not to build libev
		3421	with any compiler warnings enabled unless you are prepared to cope with
		3422	them (e.g. by ignoring them). Remember that warnings are just that:
		3423	warnings, not errors, or proof of bugs.
3385		3424
3386	This means that, when you have a watcher that triggers in one hour and
3387	there are 100 watchers that would trigger before that then inserting will
3388	have to skip roughly seven (C<ld 100>) of these watchers.
3389		3425
3390	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)	3426	=head2 VALGRIND
3391		3427
3392	That means that changing a timer costs less than removing/adding them	3428	Valgrind has a special section here because it is a popular tool that is
3393	as only the relative motion in the event queue has to be paid for.	3429	highly useful. Unfortunately, valgrind reports are very hard to interpret.
3394		3430
3395	=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)	3431	If you think you found a bug (memory leak, uninitialised data access etc.)
		3432	in libev, then check twice: If valgrind reports something like:
3396		3433
3397	These just add the watcher into an array or at the head of a list.	3434	==2274== definitely lost: 0 bytes in 0 blocks.
		3435	==2274== possibly lost: 0 bytes in 0 blocks.
		3436	==2274== still reachable: 256 bytes in 1 blocks.
3398		3437
3399	=item Stopping check/prepare/idle/fork/async watchers: O(1)	3438	Then there is no memory leak, just as memory accounted to global variables
		3439	is not a memleak - the memory is still being refernced, and didn't leak.
3400		3440
3401	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	3441	Similarly, under some circumstances, valgrind might report kernel bugs
		3442	as if it were a bug in libev (e.g. in realloc or in the poll backend,
		3443	although an acceptable workaround has been found here), or it might be
		3444	confused.
3402		3445
3403	These watchers are stored in lists then need to be walked to find the	3446	Keep in mind that valgrind is a very good tool, but only a tool. Don't
3404	correct watcher to remove. The lists are usually short (you don't usually	3447	make it into some kind of religion.
3405	have many watchers waiting for the same fd or signal).
3406		3448
3407	=item Finding the next timer in each loop iteration: O(1)	3449	If you are unsure about something, feel free to contact the mailing list
		3450	with the full valgrind report and an explanation on why you think this
		3451	is a bug in libev (best check the archives, too :). However, don't be
		3452	annoyed when you get a brisk "this is no bug" answer and take the chance
		3453	of learning how to interpret valgrind properly.
3408		3454
3409	By virtue of using a binary or 4-heap, the next timer is always found at a	3455	If you need, for some reason, empty reports from valgrind for your project
3410	fixed position in the storage array.	3456	I suggest using suppression lists.
3411		3457
3412	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3413		3458
3414	A change means an I/O watcher gets started or stopped, which requires	3459	=head1 PORTABILITY NOTES
3415	libev to recalculate its status (and possibly tell the kernel, depending
3416	on backend and whether C<ev_io_set> was used).
3417		3460
3418	=item Activating one watcher (putting it into the pending state): O(1)
3419
3420	=item Priority handling: O(number_of_priorities)
3421
3422	Priorities are implemented by allocating some space for each
3423	priority. When doing priority-based operations, libev usually has to
3424	linearly search all the priorities, but starting/stopping and activating
3425	watchers becomes O(1) w.r.t. priority handling.
3426
3427	=item Sending an ev_async: O(1)
3428
3429	=item Processing ev_async_send: O(number_of_async_watchers)
3430
3431	=item Processing signals: O(max_signal_number)
3432
3433	Sending involves a system call I<iff> there were no other C<ev_async_send>
3434	calls in the current loop iteration. Checking for async and signal events
3435	involves iterating over all running async watchers or all signal numbers.
3436
3437	=back
3438
3439
3440	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	3461	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3441		3462
3442	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3463	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3443	requires, and its I/O model is fundamentally incompatible with the POSIX	3464	requires, and its I/O model is fundamentally incompatible with the POSIX
3444	model. Libev still offers limited functionality on this platform in	3465	model. Libev still offers limited functionality on this platform in
3445	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3466	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
…		…
3456		3477
3457	Not a libev limitation but worth mentioning: windows apparently doesn't	3478	Not a libev limitation but worth mentioning: windows apparently doesn't
3458	accept large writes: instead of resulting in a partial write, windows will	3479	accept large writes: instead of resulting in a partial write, windows will
3459	either accept everything or return C<ENOBUFS> if the buffer is too large,	3480	either accept everything or return C<ENOBUFS> if the buffer is too large,
3460	so make sure you only write small amounts into your sockets (less than a	3481	so make sure you only write small amounts into your sockets (less than a
3461	megabyte seems safe, but thsi apparently depends on the amount of memory	3482	megabyte seems safe, but this apparently depends on the amount of memory
3462	available).	3483	available).
3463		3484
3464	Due to the many, low, and arbitrary limits on the win32 platform and	3485	Due to the many, low, and arbitrary limits on the win32 platform and
3465	the abysmal performance of winsockets, using a large number of sockets	3486	the abysmal performance of winsockets, using a large number of sockets
3466	is not recommended (and not reasonable). If your program needs to use	3487	is not recommended (and not reasonable). If your program needs to use
…		…
3477	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */	3498	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
3478		3499
3479	#include "ev.h"	3500	#include "ev.h"
3480		3501
3481	And compile the following F<evwrap.c> file into your project (make sure	3502	And compile the following F<evwrap.c> file into your project (make sure
3482	you do I<not> compile the F<ev.c> or any other embedded soruce files!):	3503	you do I<not> compile the F<ev.c> or any other embedded source files!):
3483		3504
3484	#include "evwrap.h"	3505	#include "evwrap.h"
3485	#include "ev.c"	3506	#include "ev.c"
3486		3507
3487	=over 4	3508	=over 4
…		…
3532	wrap all I/O functions and provide your own fd management, but the cost of	3553	wrap all I/O functions and provide your own fd management, but the cost of
3533	calling select (O(n²)) will likely make this unworkable.	3554	calling select (O(n²)) will likely make this unworkable.
3534		3555
3535	=back	3556	=back
3536		3557
3537
3538	=head1 PORTABILITY REQUIREMENTS	3558	=head2 PORTABILITY REQUIREMENTS
3539		3559
3540	In addition to a working ISO-C implementation, libev relies on a few	3560	In addition to a working ISO-C implementation and of course the
3541	additional extensions:	3561	backend-specific APIs, libev relies on a few additional extensions:
3542		3562
3543	=over 4	3563	=over 4
3544		3564
3545	=item C<void ()(ev_watcher_type , int revents)> must have compatible	3565	=item C<void ()(ev_watcher_type , int revents)> must have compatible
3546	calling conventions regardless of C<ev_watcher_type *>.	3566	calling conventions regardless of C<ev_watcher_type *>.
…		…
3552	calls them using an C<ev_watcher *> internally.	3572	calls them using an C<ev_watcher *> internally.
3553		3573
3554	=item C<sig_atomic_t volatile> must be thread-atomic as well	3574	=item C<sig_atomic_t volatile> must be thread-atomic as well
3555		3575
3556	The type C<sig_atomic_t volatile> (or whatever is defined as	3576	The type C<sig_atomic_t volatile> (or whatever is defined as
3557	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different	3577	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
3558	threads. This is not part of the specification for C<sig_atomic_t>, but is	3578	threads. This is not part of the specification for C<sig_atomic_t>, but is
3559	believed to be sufficiently portable.	3579	believed to be sufficiently portable.
3560		3580
3561	=item C<sigprocmask> must work in a threaded environment	3581	=item C<sigprocmask> must work in a threaded environment
3562		3582
…		…
3571	except the initial one, and run the default loop in the initial thread as	3591	except the initial one, and run the default loop in the initial thread as
3572	well.	3592	well.
3573		3593
3574	=item C<long> must be large enough for common memory allocation sizes	3594	=item C<long> must be large enough for common memory allocation sizes
3575		3595
3576	To improve portability and simplify using libev, libev uses C<long>	3596	To improve portability and simplify its API, libev uses C<long> internally
3577	internally instead of C<size_t> when allocating its data structures. On	3597	instead of C<size_t> when allocating its data structures. On non-POSIX
3578	non-POSIX systems (Microsoft...) this might be unexpectedly low, but	3598	systems (Microsoft...) this might be unexpectedly low, but is still at
3579	is still at least 31 bits everywhere, which is enough for hundreds of	3599	least 31 bits everywhere, which is enough for hundreds of millions of
3580	millions of watchers.	3600	watchers.
3581		3601
3582	=item C<double> must hold a time value in seconds with enough accuracy	3602	=item C<double> must hold a time value in seconds with enough accuracy
3583		3603
3584	The type C<double> is used to represent timestamps. It is required to	3604	The type C<double> is used to represent timestamps. It is required to
3585	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	3605	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
…		…
3589	=back	3609	=back
3590		3610
3591	If you know of other additional requirements drop me a note.	3611	If you know of other additional requirements drop me a note.
3592		3612
3593		3613
3594	=head1 COMPILER WARNINGS	3614	=head1 ALGORITHMIC COMPLEXITIES
3595		3615
3596	Depending on your compiler and compiler settings, you might get no or a	3616	In this section the complexities of (many of) the algorithms used inside
3597	lot of warnings when compiling libev code. Some people are apparently	3617	libev will be documented. For complexity discussions about backends see
3598	scared by this.	3618	the documentation for C<ev_default_init>.
3599		3619
3600	However, these are unavoidable for many reasons. For one, each compiler	3620	All of the following are about amortised time: If an array needs to be
3601	has different warnings, and each user has different tastes regarding	3621	extended, libev needs to realloc and move the whole array, but this
3602	warning options. "Warn-free" code therefore cannot be a goal except when	3622	happens asymptotically rarer with higher number of elements, so O(1) might
3603	targeting a specific compiler and compiler-version.	3623	mean that libev does a lengthy realloc operation in rare cases, but on
		3624	average it is much faster and asymptotically approaches constant time.
3604		3625
3605	Another reason is that some compiler warnings require elaborate	3626	=over 4
3606	workarounds, or other changes to the code that make it less clear and less
3607	maintainable.
3608		3627
3609	And of course, some compiler warnings are just plain stupid, or simply	3628	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
3610	wrong (because they don't actually warn about the condition their message
3611	seems to warn about).
3612		3629
3613	While libev is written to generate as few warnings as possible,	3630	This means that, when you have a watcher that triggers in one hour and
3614	"warn-free" code is not a goal, and it is recommended not to build libev	3631	there are 100 watchers that would trigger before that, then inserting will
3615	with any compiler warnings enabled unless you are prepared to cope with	3632	have to skip roughly seven (C<ld 100>) of these watchers.
3616	them (e.g. by ignoring them). Remember that warnings are just that:
3617	warnings, not errors, or proof of bugs.
3618		3633
		3634	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
3619		3635
3620	=head1 VALGRIND	3636	That means that changing a timer costs less than removing/adding them,
		3637	as only the relative motion in the event queue has to be paid for.
3621		3638
3622	Valgrind has a special section here because it is a popular tool that is	3639	=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)
3623	highly useful, but valgrind reports are very hard to interpret.
3624		3640
3625	If you think you found a bug (memory leak, uninitialised data access etc.)	3641	These just add the watcher into an array or at the head of a list.
3626	in libev, then check twice: If valgrind reports something like:
3627		3642
3628	==2274== definitely lost: 0 bytes in 0 blocks.	3643	=item Stopping check/prepare/idle/fork/async watchers: O(1)
3629	==2274== possibly lost: 0 bytes in 0 blocks.
3630	==2274== still reachable: 256 bytes in 1 blocks.
3631		3644
3632	Then there is no memory leak. Similarly, under some circumstances,	3645	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
3633	valgrind might report kernel bugs as if it were a bug in libev, or it
3634	might be confused (it is a very good tool, but only a tool).
3635		3646
3636	If you are unsure about something, feel free to contact the mailing list	3647	These watchers are stored in lists, so they need to be walked to find the
3637	with the full valgrind report and an explanation on why you think this is	3648	correct watcher to remove. The lists are usually short (you don't usually
3638	a bug in libev. However, don't be annoyed when you get a brisk "this is	3649	have many watchers waiting for the same fd or signal: one is typical, two
3639	no bug" answer and take the chance of learning how to interpret valgrind	3650	is rare).
3640	properly.
3641		3651
3642	If you need, for some reason, empty reports from valgrind for your project	3652	=item Finding the next timer in each loop iteration: O(1)
3643	I suggest using suppression lists.	3653
		3654	By virtue of using a binary or 4-heap, the next timer is always found at a
		3655	fixed position in the storage array.
		3656
		3657	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		3658
		3659	A change means an I/O watcher gets started or stopped, which requires
		3660	libev to recalculate its status (and possibly tell the kernel, depending
		3661	on backend and whether C<ev_io_set> was used).
		3662
		3663	=item Activating one watcher (putting it into the pending state): O(1)
		3664
		3665	=item Priority handling: O(number_of_priorities)
		3666
		3667	Priorities are implemented by allocating some space for each
		3668	priority. When doing priority-based operations, libev usually has to
		3669	linearly search all the priorities, but starting/stopping and activating
		3670	watchers becomes O(1) with respect to priority handling.
		3671
		3672	=item Sending an ev_async: O(1)
		3673
		3674	=item Processing ev_async_send: O(number_of_async_watchers)
		3675
		3676	=item Processing signals: O(max_signal_number)
		3677
		3678	Sending involves a system call I<iff> there were no other C<ev_async_send>
		3679	calls in the current loop iteration. Checking for async and signal events
		3680	involves iterating over all running async watchers or all signal numbers.
		3681
		3682	=back
3644		3683
3645		3684
3646	=head1 AUTHOR	3685	=head1 AUTHOR
3647		3686
3648	Marc Lehmann <libev@schmorp.de>.	3687	Marc Lehmann <libev@schmorp.de>.

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Comparing libev/ev.pod (file contents): Revision 1.183 by root, Tue Sep 23 08:37:38 2008 UTC vs. Revision 1.197 by root, Tue Oct 21 20:52:30 2008 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.183 by root, Tue Sep 23 08:37:38 2008 UTC vs.
Revision 1.197 by root, Tue Oct 21 20:52:30 2008 UTC