[ViewVC] Diff of: cvs/libeio/eio.pod

Comparing libeio/eio.pod (file contents):
Revision 1.9 by root, Sun Jun 5 23:07:46 2011 UTC vs.
Revision 1.22 by root, Fri Jul 8 01:12:39 2011 UTC

…		…
45	Unlike the name component C<stamp> might indicate, it is also used for	45	Unlike the name component C<stamp> might indicate, it is also used for
46	time differences throughout libeio.	46	time differences throughout libeio.
47		47
48	=head2 FORK SUPPORT	48	=head2 FORK SUPPORT
49		49
50	Calling C<fork ()> is fully supported by this module. It is implemented in these steps:	50	Calling C<fork ()> is fully supported by this module - but you must not
		51	rely on this. It is currently implemented in these steps:
51		52
52	1. wait till all requests in "execute" state have been handled	53	1. wait till all requests in "execute" state have been handled
53	(basically requests that are already handed over to the kernel).	54	(basically requests that are already handed over to the kernel).
54	2. fork	55	2. fork
55	3. in the parent, continue business as usual, done	56	3. in the parent, continue business as usual, done
56	4. in the child, destroy all ready and pending requests and free the	57	4. in the child, destroy all ready and pending requests and free the
57	memory used by the worker threads. This gives you a fully empty	58	memory used by the worker threads. This gives you a fully empty
58	libeio queue.	59	libeio queue.
59		60
60	Note, however, since libeio does use threads, thr above guarantee doesn't	61	Note, however, since libeio does use threads, the above guarantee doesn't
61	cover your libc, for example, malloc and other libc functions are not	62	cover your libc, for example, malloc and other libc functions are not
62	fork-safe, so there is very little you can do after a fork, and in fatc,	63	fork-safe, so there is very little you can do after a fork, and in fact,
63	the above might crash, and thus change.	64	the above might crash, and thus change.
64		65
65	=head1 INITIALISATION/INTEGRATION	66	=head1 INITIALISATION/INTEGRATION
66		67
67	Before you can call any eio functions you first have to initialise the	68	Before you can call any eio functions you first have to initialise the
…		…
124	=back	125	=back
125		126
126	For libev, you would typically use an C<ev_async> watcher: the	127	For libev, you would typically use an C<ev_async> watcher: the
127	C<want_poll> callback would invoke C<ev_async_send> to wake up the event	128	C<want_poll> callback would invoke C<ev_async_send> to wake up the event
128	loop. Inside the callback set for the watcher, one would call C<eio_poll	129	loop. Inside the callback set for the watcher, one would call C<eio_poll
129	()> (followed by C<ev_async_send> again if C<eio_poll> indicates that not	130	()>.
130	all requests have been handled yet). The race is taken care of because	131
131	libev resets/rearms the async watcher before calling your callback,	132	If C<eio_poll ()> is configured to not handle all results in one go
132	and therefore, before calling C<eio_poll>. This might result in (some)	133	(i.e. it returns C<-1>) then you should start an idle watcher that calls
133	spurious wake-ups, but is generally harmless.	134	C<eio_poll> until it returns something C<!= -1>.
		135
		136	A full-featured connector between libeio and libev would look as follows
		137	(if C<eio_poll> is handling all requests, it can of course be simplified a
		138	lot by removing the idle watcher logic):
		139
		140	static struct ev_loop *loop;
		141	static ev_idle repeat_watcher;
		142	static ev_async ready_watcher;
		143
		144	/* idle watcher callback, only used when eio_poll */
		145	/* didn't handle all results in one call */
		146	static void
		147	repeat (EV_P_ ev_idle *w, int revents)
		148	{
		149	if (eio_poll () != -1)
		150	ev_idle_stop (EV_A_ w);
		151	}
		152
		153	/* eio has some results, process them */
		154	static void
		155	ready (EV_P_ ev_async *w, int revents)
		156	{
		157	if (eio_poll () == -1)
		158	ev_idle_start (EV_A_ &repeat_watcher);
		159	}
		160
		161	/* wake up the event loop */
		162	static void
		163	want_poll (void)
		164	{
		165	ev_async_send (loop, &ready_watcher)
		166	}
		167
		168	void
		169	my_init_eio ()
		170	{
		171	loop = EV_DEFAULT;
		172
		173	ev_idle_init (&repeat_watcher, repeat);
		174	ev_async_init (&ready_watcher, ready);
		175	ev_async_start (loop &watcher);
		176
		177	eio_init (want_poll, 0);
		178	}
134		179
135	For most other event loops, you would typically use a pipe - the event	180	For most other event loops, you would typically use a pipe - the event
136	loop should be told to wait for read readiness on the read end. In	181	loop should be told to wait for read readiness on the read end. In
137	C<want_poll> you would write a single byte, in C<done_poll> you would try	182	C<want_poll> you would write a single byte, in C<done_poll> you would try
138	to read that byte, and in the callback for the read end, you would call	183	to read that byte, and in the callback for the read end, you would call
139	C<eio_poll>. The race is avoided here because the event loop should invoke	184	C<eio_poll>.
140	your callback again and again until the byte has been read (as the pipe	185
141	read callback does not read it, only C<done_poll>).	186	You don't have to take special care in the case C<eio_poll> doesn't handle
		187	all requests, as the done callback will not be invoked, so the event loop
		188	will still signal readiness for the pipe until I<all> results have been
		189	processed.
142		190
143		191
144	=head1 HIGH LEVEL REQUEST API	192	=head1 HIGH LEVEL REQUEST API
145		193
146	Libeio has both a high-level API, which consists of calling a request	194	Libeio has both a high-level API, which consists of calling a request
…		…
153		201
154	You submit a request by calling the relevant C<eio_TYPE> function with the	202	You submit a request by calling the relevant C<eio_TYPE> function with the
155	required parameters, a callback of type C<int (eio_cb)(eio_req req)>	203	required parameters, a callback of type C<int (eio_cb)(eio_req req)>
156	(called C<eio_cb> below) and a freely usable C<void *data> argument.	204	(called C<eio_cb> below) and a freely usable C<void *data> argument.
157		205
158	The return value will either be 0	206	The return value will either be 0, in case something went really wrong
		207	(which can basically only happen on very fatal errors, such as C<malloc>
		208	returning 0, which is rather unlikely), or a pointer to the newly-created
		209	and submitted C<eio_req *>.
159		210
160	The callback will be called with an C<eio_req *> which contains the	211	The callback will be called with an C<eio_req *> which contains the
161	results of the request. The members you can access inside that structure	212	results of the request. The members you can access inside that structure
162	vary from request to request, except for:	213	vary from request to request, except for:
163		214
…		…
210	}	261	}
211		262
212	/* the first three arguments are passed to open(2) */	263	/* the first three arguments are passed to open(2) */
213	/* the remaining are priority, callback and data */	264	/* the remaining are priority, callback and data */
214	if (!eio_open ("/etc/passwd", O_RDONLY, 0, 0, file_open_done, 0))	265	if (!eio_open ("/etc/passwd", O_RDONLY, 0, 0, file_open_done, 0))
215	abort (); /* something ent wrong, we will all die!!! */	266	abort (); /* something went wrong, we will all die!!! */
216		267
217	Note that you additionally need to call C<eio_poll> when the C<want_cb>	268	Note that you additionally need to call C<eio_poll> when the C<want_cb>
218	indicates that requests are ready to be processed.	269	indicates that requests are ready to be processed.
		270
		271	=head2 CANCELLING REQUESTS
		272
		273	Sometimes the need for a request goes away before the request is
		274	finished. In that case, one can cancel the request by a call to
		275	C<eio_cancel>:
		276
		277	=over 4
		278
		279	=item eio_cancel (eio_req *req)
		280
		281	Cancel the request (and all its subrequests). If the request is currently
		282	executing it might still continue to execute, and in other cases it might
		283	still take a while till the request is cancelled.
		284
		285	Even if cancelled, the finish callback will still be invoked - the
		286	callbacks of all cancellable requests need to check whether the request
		287	has been cancelled by calling C<EIO_CANCELLED (req)>:
		288
		289	static int
		290	my_eio_cb (eio_req *req)
		291	{
		292	if (EIO_CANCELLED (req))
		293	return 0;
		294	}
		295
		296	In addition, cancelled requests will I<either> have C<< req->result >>
		297	set to C<-1> and C<errno> to C<ECANCELED>, or I<otherwise> they were
		298	successfully executed, despite being cancelled (e.g. when they have
		299	already been executed at the time they were cancelled).
		300
		301	C<EIO_CANCELLED> is still true for requests that have successfully
		302	executed, as long as C<eio_cancel> was called on them at some point.
		303
		304	=back
219		305
220	=head2 AVAILABLE REQUESTS	306	=head2 AVAILABLE REQUESTS
221		307
222	The following request functions are available. I<All> of them return the	308	The following request functions are available. I<All> of them return the
223	C<eio_req *> on success and C<0> on failure, and I<all> of them have the	309	C<eio_req *> on success and C<0> on failure, and I<all> of them have the
…		…
226	custom data value as C<data>.	312	custom data value as C<data>.
227		313
228	=head3 POSIX API WRAPPERS	314	=head3 POSIX API WRAPPERS
229		315
230	These requests simply wrap the POSIX call of the same name, with the same	316	These requests simply wrap the POSIX call of the same name, with the same
231	arguments:	317	arguments. If a function is not implemented by the OS and cannot be emulated
		318	in some way, then all of these return C<-1> and set C<errorno> to C<ENOSYS>.
232		319
233	=over 4	320	=over 4
234		321
235	=item eio_open (const char path, int flags, mode_t mode, int pri, eio_cb cb, void data)	322	=item eio_open (const char path, int flags, mode_t mode, int pri, eio_cb cb, void data)
236		323
		324	=item eio_truncate (const char path, off_t offset, int pri, eio_cb cb, void data)
		325
		326	=item eio_chown (const char path, uid_t uid, gid_t gid, int pri, eio_cb cb, void data)
		327
		328	=item eio_chmod (const char path, mode_t mode, int pri, eio_cb cb, void data)
		329
		330	=item eio_mkdir (const char path, mode_t mode, int pri, eio_cb cb, void data)
		331
		332	=item eio_rmdir (const char path, int pri, eio_cb cb, void data)
		333
		334	=item eio_unlink (const char path, int pri, eio_cb cb, void data)
		335
237	=item eio_utime (const char path, eio_tstamp atime, eio_tstamp mtime, int pri, eio_cb cb, void data)	336	=item eio_utime (const char path, eio_tstamp atime, eio_tstamp mtime, int pri, eio_cb cb, void data)
238		337
239	=item eio_truncate (const char path, off_t offset, int pri, eio_cb cb, void data)
240
241	=item eio_chown (const char path, uid_t uid, gid_t gid, int pri, eio_cb cb, void data)
242
243	=item eio_chmod (const char path, mode_t mode, int pri, eio_cb cb, void data)
244
245	=item eio_mkdir (const char path, mode_t mode, int pri, eio_cb cb, void data)
246
247	=item eio_rmdir (const char path, int pri, eio_cb cb, void data)
248
249	=item eio_unlink (const char path, int pri, eio_cb cb, void data)
250
251	=item eio_readlink (const char path, int pri, eio_cb cb, void data) /* result=ptr2 allocated dynamically */
252
253	=item eio_stat (const char path, int pri, eio_cb cb, void data) /* stat buffer=ptr2 allocated dynamically */
254
255	=item eio_lstat (const char path, int pri, eio_cb cb, void data) /* stat buffer=ptr2 allocated dynamically */
256
257	=item eio_statvfs (const char path, int pri, eio_cb cb, void data) /* stat buffer=ptr2 allocated dynamically */
258
259	=item eio_mknod (const char path, mode_t mode, dev_t dev, int pri, eio_cb cb, void data)	338	=item eio_mknod (const char path, mode_t mode, dev_t dev, int pri, eio_cb cb, void data)
260		339
261	=item eio_link (const char path, const char new_path, int pri, eio_cb cb, void *data)	340	=item eio_link (const char path, const char new_path, int pri, eio_cb cb, void *data)
262		341
263	=item eio_symlink (const char path, const char new_path, int pri, eio_cb cb, void *data)	342	=item eio_symlink (const char path, const char new_path, int pri, eio_cb cb, void *data)
264		343
265	=item eio_rename (const char path, const char new_path, int pri, eio_cb cb, void *data)	344	=item eio_rename (const char path, const char new_path, int pri, eio_cb cb, void *data)
266		345
267	=item eio_msync (void addr, size_t length, int flags, int pri, eio_cb cb, void data)
268
269	=item eio_mlock (void addr, size_t length, int pri, eio_cb cb, void data)	346	=item eio_mlock (void addr, size_t length, int pri, eio_cb cb, void data)
270
271	=item eio_mlockall (int flags, int pri, eio_cb cb, void *data)
272		347
273	=item eio_close (int fd, int pri, eio_cb cb, void *data)	348	=item eio_close (int fd, int pri, eio_cb cb, void *data)
274		349
275	=item eio_sync (int pri, eio_cb cb, void *data)	350	=item eio_sync (int pri, eio_cb cb, void *data)
276		351
…		…
305		380
306	Not surprisingly, pread and pwrite are not thread-safe on Darwin (OS/X),	381	Not surprisingly, pread and pwrite are not thread-safe on Darwin (OS/X),
307	so it is advised not to submit multiple requests on the same fd on this	382	so it is advised not to submit multiple requests on the same fd on this
308	horrible pile of garbage.	383	horrible pile of garbage.
309		384
		385	=item eio_mlockall (int flags, int pri, eio_cb cb, void *data)
		386
		387	Like C<mlockall>, but the flag value constants are called
		388	C<EIO_MCL_CURRENT> and C<EIO_MCL_FUTURE>.
		389
		390	=item eio_msync (void addr, size_t length, int flags, int pri, eio_cb cb, void data)
		391
		392	Just like msync, except that the flag values are called C<EIO_MS_ASYNC>,
		393	C<EIO_MS_INVALIDATE> and C<EIO_MS_SYNC>.
		394
		395	=item eio_readlink (const char path, int pri, eio_cb cb, void data)
		396
		397	If successful, the path read by C<readlink(2)> can be accessed via C<<
		398	req->ptr2 >> and is I<NOT> null-terminated, with the length specified as
		399	C<< req->result >>.
		400
		401	if (req->result >= 0)
		402	{
		403	char target = strndup ((char )req->ptr2, req->result);
		404
		405	free (target);
		406	}
		407
		408	=item eio_realpath (const char path, int pri, eio_cb cb, void data)
		409
		410	Similar to the realpath libc function, but unlike that one, C<<
		411	req->result >> is C<-1> on failure. On success, the result is the length
		412	of the returned path in C<ptr2> (which is I<NOT> 0-terminated) - this is
		413	similar to readlink.
		414
		415	=item eio_stat (const char path, int pri, eio_cb cb, void data)
		416
		417	=item eio_lstat (const char path, int pri, eio_cb cb, void data)
		418
310	=item eio_fstat (int fd, int pri, eio_cb cb, void *data)	419	=item eio_fstat (int fd, int pri, eio_cb cb, void *data)
311		420
312	Stats a file - if C<< req->result >> indicates success, then you can	421	Stats a file - if C<< req->result >> indicates success, then you can
313	access the C<struct stat>-like structure via C<< req->ptr2 >>:	422	access the C<struct stat>-like structure via C<< req->ptr2 >>:
314		423
315	EIO_STRUCT_STAT statdata = (EIO_STRUCT_STAT )req->ptr2;	424	EIO_STRUCT_STAT statdata = (EIO_STRUCT_STAT )req->ptr2;
316		425
317	=item eio_fstatvfs (int fd, int pri, eio_cb cb, void data) / stat buffer=ptr2 allocated dynamically */	426	=item eio_statvfs (const char path, int pri, eio_cb cb, void data)
		427
		428	=item eio_fstatvfs (int fd, int pri, eio_cb cb, void *data)
318		429
319	Stats a filesystem - if C<< req->result >> indicates success, then you can	430	Stats a filesystem - if C<< req->result >> indicates success, then you can
320	access the C<struct statvfs>-like structure via C<< req->ptr2 >>:	431	access the C<struct statvfs>-like structure via C<< req->ptr2 >>:
321		432
322	EIO_STRUCT_STATVFS statdata = (EIO_STRUCT_STATVFS )req->ptr2;	433	EIO_STRUCT_STATVFS statdata = (EIO_STRUCT_STATVFS )req->ptr2;
323		434
324	=back	435	=back
325		436
326	=head3 READING DIRECTORIES	437	=head3 READING DIRECTORIES
327		438
328	Reading directories sounds simple, but can be rather demanding, especially	439	Reading directories sounds simple, but can be rather demanding, especially
329	if you want to do stuff such as traversing a diretcory hierarchy or	440	if you want to do stuff such as traversing a directory hierarchy or
330	processing all files in a directory. Libeio can assist thess complex tasks	441	processing all files in a directory. Libeio can assist these complex tasks
331	with it's C<eio_readdir> call.	442	with it's C<eio_readdir> call.
332		443
333	=over 4	444	=over 4
334		445
335	=item eio_readdir (const char path, int flags, int pri, eio_cb cb, void data)	446	=item eio_readdir (const char path, int flags, int pri, eio_cb cb, void data)
…		…
338	(via the C<opendir>, C<readdir> and C<closedir> calls) and returns either	449	(via the C<opendir>, C<readdir> and C<closedir> calls) and returns either
339	the names or an array of C<struct eio_dirent>, depending on the C<flags>	450	the names or an array of C<struct eio_dirent>, depending on the C<flags>
340	argument.	451	argument.
341		452
342	The C<< req->result >> indicates either the number of files found, or	453	The C<< req->result >> indicates either the number of files found, or
343	C<-1> on error. On success, zero-terminated names can be found as C<< req->ptr2 >>,	454	C<-1> on error. On success, null-terminated names can be found as C<< req->ptr2 >>,
344	and C<struct eio_dirents>, if requested by C<flags>, can be found via C<<	455	and C<struct eio_dirents>, if requested by C<flags>, can be found via C<<
345	req->ptr1 >>.	456	req->ptr1 >>.
346		457
347	Here is an example that prints all the names:	458	Here is an example that prints all the names:
348		459
…		…
367		478
368	If this flag is specified, then, in addition to the names in C<ptr2>,	479	If this flag is specified, then, in addition to the names in C<ptr2>,
369	also an array of C<struct eio_dirent> is returned, in C<ptr1>. A C<struct	480	also an array of C<struct eio_dirent> is returned, in C<ptr1>. A C<struct
370	eio_dirent> looks like this:	481	eio_dirent> looks like this:
371		482
372	struct eio_dirent	483	struct eio_dirent
373	{	484	{
374	int nameofs; /* offset of null-terminated name string in (char )req->ptr2 /	485	int nameofs; /* offset of null-terminated name string in (char )req->ptr2 /
375	unsigned short namelen; /* size of filename without trailing 0 */	486	unsigned short namelen; /* size of filename without trailing 0 */
376	unsigned char type; /* one of EIO_DT_* */	487	unsigned char type; /* one of EIO_DT_* */
377	signed char score; /* internal use */	488	signed char score; /* internal use */
378	ino_t inode; /* the inode number, if available, otherwise unspecified */	489	ino_t inode; /* the inode number, if available, otherwise unspecified */
379	};	490	};
380		491
381	The only members you normally would access are C<nameofs>, which is the	492	The only members you normally would access are C<nameofs>, which is the
382	byte-offset from C<ptr2> to the start of the name, C<namelen> and C<type>.	493	byte-offset from C<ptr2> to the start of the name, C<namelen> and C<type>.
383		494
384	C<type> can be one of:	495	C<type> can be one of:
…		…
427	When this flag is specified, then the names will be returned in an order	538	When this flag is specified, then the names will be returned in an order
428	suitable for stat()'ing each one. That is, when you plan to stat()	539	suitable for stat()'ing each one. That is, when you plan to stat()
429	all files in the given directory, then the returned order will likely	540	all files in the given directory, then the returned order will likely
430	be fastest.	541	be fastest.
431		542
432	If both this flag and C<EIO_READDIR_DIRS_FIRST> are specified, then	543	If both this flag and C<EIO_READDIR_DIRS_FIRST> are specified, then the
433	the likely dirs come first, resulting in a less optimal stat order.	544	likely directories come first, resulting in a less optimal stat order.
434		545
435	=item EIO_READDIR_FOUND_UNKNOWN	546	=item EIO_READDIR_FOUND_UNKNOWN
436		547
437	This flag should not be specified when calling C<eio_readdir>. Instead,	548	This flag should not be specified when calling C<eio_readdir>. Instead,
438	it is being set by C<eio_readdir> (you can access the C<flags> via C<<	549	it is being set by C<eio_readdir> (you can access the C<flags> via C<<
439	req->int1 >>, when any of the C<type>'s found were C<EIO_DT_UNKNOWN>. The	550	req->int1 >>, when any of the C<type>'s found were C<EIO_DT_UNKNOWN>. The
440	absense of this flag therefore indicates that all C<type>'s are known,	551	absence of this flag therefore indicates that all C<type>'s are known,
441	which can be used to speed up some algorithms.	552	which can be used to speed up some algorithms.
442		553
443	A typical use case would be to identify all subdirectories within a	554	A typical use case would be to identify all subdirectories within a
444	directory - you would ask C<eio_readdir> for C<EIO_READDIR_DIRS_FIRST>. If	555	directory - you would ask C<eio_readdir> for C<EIO_READDIR_DIRS_FIRST>. If
445	then this flag is I<NOT> set, then all the entries at the beginning of the	556	then this flag is I<NOT> set, then all the entries at the beginning of the
…		…
480	=item eio_sync_file_range (int fd, off_t offset, size_t nbytes, unsigned int flags, int pri, eio_cb cb, void *data)	591	=item eio_sync_file_range (int fd, off_t offset, size_t nbytes, unsigned int flags, int pri, eio_cb cb, void *data)
481		592
482	Calls C<sync_file_range>. If the syscall is missing, then this is the same	593	Calls C<sync_file_range>. If the syscall is missing, then this is the same
483	as calling C<fdatasync>.	594	as calling C<fdatasync>.
484		595
		596	Flags can be any combination of C<EIO_SYNC_FILE_RANGE_WAIT_BEFORE>,
		597	C<EIO_SYNC_FILE_RANGE_WRITE> and C<EIO_SYNC_FILE_RANGE_WAIT_AFTER>.
		598
		599	=item eio_fallocate (int fd, int mode, off_t offset, off_t len, int pri, eio_cb cb, void *data)
		600
		601	Calls C<fallocate> (note: I<NOT> C<posix_fallocate>!). If the syscall is
		602	missing, then it returns failure and sets C<errno> to C<ENOSYS>.
		603
		604	The C<mode> argument can be C<0> (for behaviour similar to
		605	C<posix_fallocate>), or C<EIO_FALLOC_FL_KEEP_SIZE>, which keeps the size
		606	of the file unchanged (but still preallocates space beyond end of file).
		607
485	=back	608	=back
486		609
487	=head3 LIBEIO-SPECIFIC REQUESTS	610	=head3 LIBEIO-SPECIFIC REQUESTS
488		611
489	These requests are specific to libeio and do not correspond to any OS call.	612	These requests are specific to libeio and do not correspond to any OS call.
…		…
530		653
531	eio_custom (my_open, 0, my_open_done, "/etc/passwd");	654	eio_custom (my_open, 0, my_open_done, "/etc/passwd");
532		655
533	=item eio_busy (eio_tstamp delay, int pri, eio_cb cb, void *data)	656	=item eio_busy (eio_tstamp delay, int pri, eio_cb cb, void *data)
534		657
535	This is a a request that takes C<delay> seconds to execute, but otherwise	658	This is a request that takes C<delay> seconds to execute, but otherwise
536	does nothing - it simply puts one of the worker threads to sleep for this	659	does nothing - it simply puts one of the worker threads to sleep for this
537	long.	660	long.
538		661
539	This request can be used to artificially increase load, e.g. for debugging	662	This request can be used to artificially increase load, e.g. for debugging
540	or benchmarking reasons.	663	or benchmarking reasons.
…		…
547		670
548	=back	671	=back
549		672
550	=head3 GROUPING AND LIMITING REQUESTS	673	=head3 GROUPING AND LIMITING REQUESTS
551		674
		675	There is one more rather special request, C<eio_grp>. It is a very special
		676	aio request: Instead of doing something, it is a container for other eio
		677	requests.
		678
		679	There are two primary use cases for this: a) bundle many requests into a
		680	single, composite, request with a definite callback and the ability to
		681	cancel the whole request with its subrequests and b) limiting the number
		682	of "active" requests.
		683
		684	Further below you will find more discussion of these topics - first
		685	follows the reference section detailing the request generator and other
		686	methods.
		687
		688	=over 4
		689
		690	=item eio_req grp = eio_grp (eio_cb cb, void data)
		691
		692	Creates, submits and returns a group request.
		693
		694	=item eio_grp_add (eio_req grp, eio_req req)
		695
		696	Adds a request to the request group.
		697
		698	=item eio_grp_cancel (eio_req *grp)
		699
		700	Cancels all requests I<in> the group, but I<not> the group request
		701	itself. You can cancel the group request via a normal C<eio_cancel> call.
		702
		703
		704
		705	=back
		706
		707
		708
552	#TODO	709	#TODO
553		710
554	/*****************************************************************************/	711	/*****************************************************************************/
555	/* groups */	712	/* groups */
556		713
557	eio_req eio_grp (eio_cb cb, void data);	714	eio_req eio_grp (eio_cb cb, void data);
558	void eio_grp_feed (eio_req grp, void (feed)(eio_req *req), int limit);	715	void eio_grp_feed (eio_req grp, void (feed)(eio_req *req), int limit);
559	void eio_grp_limit (eio_req *grp, int limit);	716	void eio_grp_limit (eio_req *grp, int limit);
560	void eio_grp_add (eio_req grp, eio_req req);
561	void eio_grp_cancel (eio_req grp); / cancels all sub requests but not the group */	717	void eio_grp_cancel (eio_req grp); / cancels all sub requests but not the group */
562		718
563		719
564	=back	720	=back
565		721
…		…
572	=head1 ANATOMY AND LIFETIME OF AN EIO REQUEST	728	=head1 ANATOMY AND LIFETIME OF AN EIO REQUEST
573		729
574	A request is represented by a structure of type C<eio_req>. To initialise	730	A request is represented by a structure of type C<eio_req>. To initialise
575	it, clear it to all zero bytes:	731	it, clear it to all zero bytes:
576		732
577	eio_req req;	733	eio_req req;
578		734
579	memset (&req, 0, sizeof (req));	735	memset (&req, 0, sizeof (req));
580		736
581	A more common way to initialise a new C<eio_req> is to use C<calloc>:	737	A more common way to initialise a new C<eio_req> is to use C<calloc>:
582		738
583	eio_req req = calloc (1, sizeof (req));	739	eio_req req = calloc (1, sizeof (req));
584		740
585	In either case, libeio neither allocates, initialises or frees the	741	In either case, libeio neither allocates, initialises or frees the
586	C<eio_req> structure for you - it merely uses it.	742	C<eio_req> structure for you - it merely uses it.
587		743
588	zero	744	zero
…		…
606	for example, in interactive programs, you might want to limit this time to	762	for example, in interactive programs, you might want to limit this time to
607	C<0.01> seconds or so.	763	C<0.01> seconds or so.
608		764
609	Note that:	765	Note that:
610		766
		767	=over 4
		768
611	a) libeio doesn't know how long your request callbacks take, so the time	769	=item a) libeio doesn't know how long your request callbacks take, so the
612	spent in C<eio_poll> is up to one callback invocation longer then this	770	time spent in C<eio_poll> is up to one callback invocation longer then
613	interval.	771	this interval.
614		772
615	b) this is implemented by calling C<gettimeofday> after each request,	773	=item b) this is implemented by calling C<gettimeofday> after each
616	which can be costly.	774	request, which can be costly.
617		775
618	c) at least one request will be handled.	776	=item c) at least one request will be handled.
		777
		778	=back
619		779
620	=item eio_set_max_poll_reqs (unsigned int nreqs)	780	=item eio_set_max_poll_reqs (unsigned int nreqs)
621		781
622	When C<nreqs> is non-zero, then C<eio_poll> will not handle more than	782	When C<nreqs> is non-zero, then C<eio_poll> will not handle more than
623	C<nreqs> requests per invocation. This is a less costly way to limit the	783	C<nreqs> requests per invocation. This is a less costly way to limit the

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Comparing libeio/eio.pod (file contents): Revision 1.9 by root, Sun Jun 5 23:07:46 2011 UTC vs. Revision 1.22 by root, Fri Jul 8 01:12:39 2011 UTC

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Comparing libeio/eio.pod (file contents):
Revision 1.9 by root, Sun Jun 5 23:07:46 2011 UTC vs.
Revision 1.22 by root, Fri Jul 8 01:12:39 2011 UTC