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

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Revision 1.4 by root, Wed Apr 22 11:04:49 2009 UTC vs.
Revision 1.10 by root, Sun Jun 5 23:22:04 2011 UTC

…		…
11	The newest version of this document is also available as an html-formatted	11	The newest version of this document is also available as an html-formatted
12	web page you might find easier to navigate when reading it for the first	12	web page you might find easier to navigate when reading it for the first
13	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libeio/eio.pod>.	13	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libeio/eio.pod>.
14		14
15	Note that this library is a by-product of the C<IO::AIO> perl	15	Note that this library is a by-product of the C<IO::AIO> perl
16	module, and many of the subtler points regarding requets lifetime	16	module, and many of the subtler points regarding requests lifetime
17	and so on are only documented in its documentation at the	17	and so on are only documented in its documentation at the
18	moment: L<http://pod.tst.eu/http://cvs.schmorp.de/IO-AIO/AIO.pm>.	18	moment: L<http://pod.tst.eu/http://cvs.schmorp.de/IO-AIO/AIO.pm>.
19		19
20	=head2 FEATURES	20	=head2 FEATURES
21		21
22	This library provides fully asynchronous versions of most POSIX functions	22	This library provides fully asynchronous versions of most POSIX functions
23	dealign with I/O. Unlike most asynchronous libraries, this not only	23	dealing with I/O. Unlike most asynchronous libraries, this not only
24	includes C<read> and C<write>, but also C<open>, C<stat>, C<unlink> and	24	includes C<read> and C<write>, but also C<open>, C<stat>, C<unlink> and
25	similar functions, as well as less rarely ones such as C<mknod>, C<futime>	25	similar functions, as well as less rarely ones such as C<mknod>, C<futime>
26	or C<readlink>.	26	or C<readlink>.
27		27
28	It also offers wrappers around C<sendfile> (Solaris, Linux, HP-UX and	28	It also offers wrappers around C<sendfile> (Solaris, Linux, HP-UX and
29	FreeBSD, with emulation on other platforms) and C<readahead> (Linux, with	29	FreeBSD, with emulation on other platforms) and C<readahead> (Linux, with
30	emulation elsewhere>).	30	emulation elsewhere>).
31		31
32	The goal is to enbale you to write fully non-blocking programs. For	32	The goal is to enable you to write fully non-blocking programs. For
33	example, in a game server, you would not want to freeze for a few seconds	33	example, in a game server, you would not want to freeze for a few seconds
34	just because the server is running a backup and you happen to call	34	just because the server is running a backup and you happen to call
35	C<readdir>.	35	C<readdir>.
36		36
37	=head2 TIME REPRESENTATION	37	=head2 TIME REPRESENTATION
38		38
39	Libeio represents time as a single floating point number, representing the	39	Libeio represents time as a single floating point number, representing the
40	(fractional) number of seconds since the (POSIX) epoch (somewhere near	40	(fractional) number of seconds since the (POSIX) epoch (somewhere near
41	the beginning of 1970, details are complicated, don't ask). This type is	41	the beginning of 1970, details are complicated, don't ask). This type is
42	called C<eio_tstamp>, but it is guarenteed to be of type C<double> (or	42	called C<eio_tstamp>, but it is guaranteed to be of type C<double> (or
43	better), so you can freely use C<double> yourself.	43	better), so you can freely use C<double> yourself.
44		44
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
…		…
55	3. in the parent, continue business as usual, done	55	3. in the parent, continue business as usual, done
56	4. in the child, destroy all ready and pending requests and free the	56	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	57	memory used by the worker threads. This gives you a fully empty
58	libeio queue.	58	libeio queue.
59		59
		60	Note, however, since libeio does use threads, thr above guarantee doesn't
		61	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	the above might crash, and thus change.
		64
60	=head1 INITIALISATION/INTEGRATION	65	=head1 INITIALISATION/INTEGRATION
61		66
62	Before you can call any eio functions you first have to initialise the	67	Before you can call any eio functions you first have to initialise the
63	library. The library integrates into any event loop, but can also be used	68	library. The library integrates into any event loop, but can also be used
64	without one, including in polling mode.	69	without one, including in polling mode.
…		…
97	handled or C<done_poll> has been called, which signals the same.	102	handled or C<done_poll> has been called, which signals the same.
98		103
99	Note that C<eio_poll> might return after C<done_poll> and C<want_poll>	104	Note that C<eio_poll> might return after C<done_poll> and C<want_poll>
100	have been called again, so watch out for races in your code.	105	have been called again, so watch out for races in your code.
101		106
102	As with C<want_poll>, this callback is called while lcoks are being held,	107	As with C<want_poll>, this callback is called while locks are being held,
103	so you I<must not call any libeio functions form within this callback>.	108	so you I<must not call any libeio functions form within this callback>.
104		109
105	=item int eio_poll ()	110	=item int eio_poll ()
106		111
107	This function has to be called whenever there are pending requests that	112	This function has to be called whenever there are pending requests that
…		…
126	libev resets/rearms the async watcher before calling your callback,	131	libev resets/rearms the async watcher before calling your callback,
127	and therefore, before calling C<eio_poll>. This might result in (some)	132	and therefore, before calling C<eio_poll>. This might result in (some)
128	spurious wake-ups, but is generally harmless.	133	spurious wake-ups, but is generally harmless.
129		134
130	For most other event loops, you would typically use a pipe - the event	135	For most other event loops, you would typically use a pipe - the event
131	loop should be told to wait for read readyness on the read end. In	136	loop should be told to wait for read readiness on the read end. In
132	C<want_poll> you would write a single byte, in C<done_poll> you would try	137	C<want_poll> you would write a single byte, in C<done_poll> you would try
133	to read that byte, and in the callback for the read end, you would call	138	to read that byte, and in the callback for the read end, you would call
134	C<eio_poll>. The race is avoided here because the event loop should invoke	139	C<eio_poll>. The race is avoided here because the event loop should invoke
135	your callback again and again until the byte has been read (as the pipe	140	your callback again and again until the byte has been read (as the pipe
136	read callback does not read it, only C<done_poll>).	141	read callback does not read it, only C<done_poll>).
137		142
		143
		144	=head1 HIGH LEVEL REQUEST API
		145
		146	Libeio has both a high-level API, which consists of calling a request
		147	function with a callback to be called on completion, and a low-level API
		148	where you fill out request structures and submit them.
		149
		150	This section describes the high-level API.
		151
		152	=head2 REQUEST SUBMISSION AND RESULT PROCESSING
		153
		154	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)>
		156	(called C<eio_cb> below) and a freely usable C<void *data> argument.
		157
		158	The return value will either be 0
		159
		160	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
		162	vary from request to request, except for:
		163
		164	=over 4
		165
		166	=item C<ssize_t result>
		167
		168	This contains the result value from the call (usually the same as the
		169	syscall of the same name).
		170
		171	=item C<int errorno>
		172
		173	This contains the value of C<errno> after the call.
		174
		175	=item C<void *data>
		176
		177	The C<void *data> member simply stores the value of the C<data> argument.
		178
		179	=back
		180
		181	The return value of the callback is normally C<0>, which tells libeio to
		182	continue normally. If a callback returns a nonzero value, libeio will
		183	stop processing results (in C<eio_poll>) and will return the value to its
		184	caller.
		185
		186	Memory areas passed to libeio must stay valid as long as a request
		187	executes, with the exception of paths, which are being copied
		188	internally. Any memory libeio itself allocates will be freed after the
		189	finish callback has been called. If you want to manage all memory passed
		190	to libeio yourself you can use the low-level API.
		191
		192	For example, to open a file, you could do this:
		193
		194	static int
		195	file_open_done (eio_req *req)
		196	{
		197	if (req->result < 0)
		198	{
		199	/* open() returned -1 */
		200	errno = req->errorno;
		201	perror ("open");
		202	}
		203	else
		204	{
		205	int fd = req->result;
		206	/* now we have the new fd in fd */
		207	}
		208
		209	return 0;
		210	}
		211
		212	/* the first three arguments are passed to open(2) */
		213	/* the remaining are priority, callback and data */
		214	if (!eio_open ("/etc/passwd", O_RDONLY, 0, 0, file_open_done, 0))
		215	abort (); /* something ent wrong, we will all die!!! */
		216
		217	Note that you additionally need to call C<eio_poll> when the C<want_cb>
		218	indicates that requests are ready to be processed.
		219
		220	=head2 AVAILABLE REQUESTS
		221
		222	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
		224	same three trailing arguments: C<pri>, C<cb> and C<data>. The C<cb> is
		225	mandatory, but in most cases, you pass in C<0> as C<pri> and C<0> or some
		226	custom data value as C<data>.
		227
		228	=head3 POSIX API WRAPPERS
		229
		230	These requests simply wrap the POSIX call of the same name, with the same
		231	arguments. If a function is not implemented by the OS and cnanot be emulated
		232	in some way, then all of these return C<-1> and set C<errorno> to C<ENOSYS>.
		233
		234	=over 4
		235
		236	=item eio_open (const char path, int flags, mode_t mode, int pri, eio_cb cb, void data)
		237
		238	=item eio_truncate (const char path, off_t offset, int pri, eio_cb cb, void data)
		239
		240	=item eio_chown (const char path, uid_t uid, gid_t gid, int pri, eio_cb cb, void data)
		241
		242	=item eio_chmod (const char path, mode_t mode, int pri, eio_cb cb, void data)
		243
		244	=item eio_mkdir (const char path, mode_t mode, int pri, eio_cb cb, void data)
		245
		246	=item eio_rmdir (const char path, int pri, eio_cb cb, void data)
		247
		248	=item eio_unlink (const char path, int pri, eio_cb cb, void data)
		249
		250	=item eio_utime (const char path, eio_tstamp atime, eio_tstamp mtime, int pri, eio_cb cb, void data)
		251
		252	=item eio_mknod (const char path, mode_t mode, dev_t dev, int pri, eio_cb cb, void data)
		253
		254	=item eio_link (const char path, const char new_path, int pri, eio_cb cb, void *data)
		255
		256	=item eio_symlink (const char path, const char new_path, int pri, eio_cb cb, void *data)
		257
		258	=item eio_rename (const char path, const char new_path, int pri, eio_cb cb, void *data)
		259
		260	=item eio_mlock (void addr, size_t length, int pri, eio_cb cb, void data)
		261
		262	=item eio_close (int fd, int pri, eio_cb cb, void *data)
		263
		264	=item eio_sync (int pri, eio_cb cb, void *data)
		265
		266	=item eio_fsync (int fd, int pri, eio_cb cb, void *data)
		267
		268	=item eio_fdatasync (int fd, int pri, eio_cb cb, void *data)
		269
		270	=item eio_futime (int fd, eio_tstamp atime, eio_tstamp mtime, int pri, eio_cb cb, void *data)
		271
		272	=item eio_ftruncate (int fd, off_t offset, int pri, eio_cb cb, void *data)
		273
		274	=item eio_fchmod (int fd, mode_t mode, int pri, eio_cb cb, void *data)
		275
		276	=item eio_fchown (int fd, uid_t uid, gid_t gid, int pri, eio_cb cb, void *data)
		277
		278	=item eio_dup2 (int fd, int fd2, int pri, eio_cb cb, void *data)
		279
		280	These have the same semantics as the syscall of the same name, their
		281	return value is available as C<< req->result >> later.
		282
		283	=item eio_read (int fd, void buf, size_t length, off_t offset, int pri, eio_cb cb, void data)
		284
		285	=item eio_write (int fd, void buf, size_t length, off_t offset, int pri, eio_cb cb, void data)
		286
		287	These two requests are called C<read> and C<write>, but actually wrap
		288	C<pread> and C<pwrite>. On systems that lack these calls (such as cygwin),
		289	libeio uses lseek/read_or_write/lseek and a mutex to serialise the
		290	requests, so all these requests run serially and do not disturb each
		291	other. However, they still disturb the file offset while they run, so it's
		292	not safe to call these functions concurrently with non-libeio functions on
		293	the same fd on these systems.
		294
		295	Not surprisingly, pread and pwrite are not thread-safe on Darwin (OS/X),
		296	so it is advised not to submit multiple requests on the same fd on this
		297	horrible pile of garbage.
		298
		299	=item eio_mlockall (int flags, int pri, eio_cb cb, void *data)
		300
		301	Like C<mlockall>, but the flag value constants are called
		302	C<EIO_MCL_CURRENT> and C<EIO_MCL_FUTURE>.
		303
		304	=item eio_msync (void addr, size_t length, int flags, int pri, eio_cb cb, void data)
		305
		306	Just like msync, except that the flag values are called C<EIO_MS_ASYNC>,
		307	C<EIO_MS_INVALIDATE> and C<EIO_MS_SYNC>.
		308
		309	=item eio_readlink (const char path, int pri, eio_cb cb, void data)
		310
		311	If successful, the path read by C<readlink(2)> can be accessed via C<<
		312	req->ptr2 >> and is I<NOT> null-terminated, with the length specified as
		313	C<< req->result >>.
		314
		315	if (req->result >= 0)
		316	{
		317	char target = strndup ((char )req->ptr2, req->result);
		318
		319	free (target);
		320	}
		321
		322	=item eio_stat (const char path, int pri, eio_cb cb, void data)
		323
		324	=item eio_lstat (const char path, int pri, eio_cb cb, void data)
		325
		326	=item eio_fstat (int fd, int pri, eio_cb cb, void *data)
		327
		328	Stats a file - if C<< req->result >> indicates success, then you can
		329	access the C<struct stat>-like structure via C<< req->ptr2 >>:
		330
		331	EIO_STRUCT_STAT statdata = (EIO_STRUCT_STAT )req->ptr2;
		332
		333	=item eio_statvfs (const char path, int pri, eio_cb cb, void data)
		334
		335	=item eio_fstatvfs (int fd, int pri, eio_cb cb, void *data)
		336
		337	Stats a filesystem - if C<< req->result >> indicates success, then you can
		338	access the C<struct statvfs>-like structure via C<< req->ptr2 >>:
		339
		340	EIO_STRUCT_STATVFS statdata = (EIO_STRUCT_STATVFS )req->ptr2;
		341
		342	=back
		343
		344	=head3 READING DIRECTORIES
		345
		346	Reading directories sounds simple, but can be rather demanding, especially
		347	if you want to do stuff such as traversing a diretcory hierarchy or
		348	processing all files in a directory. Libeio can assist thess complex tasks
		349	with it's C<eio_readdir> call.
		350
		351	=over 4
		352
		353	=item eio_readdir (const char path, int flags, int pri, eio_cb cb, void data)
		354
		355	This is a very complex call. It basically reads through a whole directory
		356	(via the C<opendir>, C<readdir> and C<closedir> calls) and returns either
		357	the names or an array of C<struct eio_dirent>, depending on the C<flags>
		358	argument.
		359
		360	The C<< req->result >> indicates either the number of files found, or
		361	C<-1> on error. On success, null-terminated names can be found as C<< req->ptr2 >>,
		362	and C<struct eio_dirents>, if requested by C<flags>, can be found via C<<
		363	req->ptr1 >>.
		364
		365	Here is an example that prints all the names:
		366
		367	int i;
		368	char names = (char )req->ptr2;
		369
		370	for (i = 0; i < req->result; ++i)
		371	{
		372	printf ("name #%d: %s\n", i, names);
		373
		374	/* move to next name */
		375	names += strlen (names) + 1;
		376	}
		377
		378	Pseudo-entries such as F<.> and F<..> are never returned by C<eio_readdir>.
		379
		380	C<flags> can be any combination of:
		381
		382	=over 4
		383
		384	=item EIO_READDIR_DENTS
		385
		386	If this flag is specified, then, in addition to the names in C<ptr2>,
		387	also an array of C<struct eio_dirent> is returned, in C<ptr1>. A C<struct
		388	eio_dirent> looks like this:
		389
		390	struct eio_dirent
		391	{
		392	int nameofs; /* offset of null-terminated name string in (char )req->ptr2 /
		393	unsigned short namelen; /* size of filename without trailing 0 */
		394	unsigned char type; /* one of EIO_DT_* */
		395	signed char score; /* internal use */
		396	ino_t inode; /* the inode number, if available, otherwise unspecified */
		397	};
		398
		399	The only members you normally would access are C<nameofs>, which is the
		400	byte-offset from C<ptr2> to the start of the name, C<namelen> and C<type>.
		401
		402	C<type> can be one of:
		403
		404	C<EIO_DT_UNKNOWN> - if the type is not known (very common) and you have to C<stat>
		405	the name yourself if you need to know,
		406	one of the "standard" POSIX file types (C<EIO_DT_REG>, C<EIO_DT_DIR>, C<EIO_DT_LNK>,
		407	C<EIO_DT_FIFO>, C<EIO_DT_SOCK>, C<EIO_DT_CHR>, C<EIO_DT_BLK>)
		408	or some OS-specific type (currently
		409	C<EIO_DT_MPC> - multiplexed char device (v7+coherent),
		410	C<EIO_DT_NAM> - xenix special named file,
		411	C<EIO_DT_MPB> - multiplexed block device (v7+coherent),
		412	C<EIO_DT_NWK> - HP-UX network special,
		413	C<EIO_DT_CMP> - VxFS compressed,
		414	C<EIO_DT_DOOR> - solaris door, or
		415	C<EIO_DT_WHT>).
		416
		417	This example prints all names and their type:
		418
		419	int i;
		420	struct eio_dirent ents = (struct eio_dirent )req->ptr1;
		421	char names = (char )req->ptr2;
		422
		423	for (i = 0; i < req->result; ++i)
		424	{
		425	struct eio_dirent *ent = ents + i;
		426	char *name = names + ent->nameofs;
		427
		428	printf ("name #%d: %s (type %d)\n", i, name, ent->type);
		429	}
		430
		431	=item EIO_READDIR_DIRS_FIRST
		432
		433	When this flag is specified, then the names will be returned in an order
		434	where likely directories come first, in optimal C<stat> order. This is
		435	useful when you need to quickly find directories, or you want to find all
		436	directories while avoiding to stat() each entry.
		437
		438	If the system returns type information in readdir, then this is used
		439	to find directories directly. Otherwise, likely directories are names
		440	beginning with ".", or otherwise names with no dots, of which names with
		441	short names are tried first.
		442
		443	=item EIO_READDIR_STAT_ORDER
		444
		445	When this flag is specified, then the names will be returned in an order
		446	suitable for stat()'ing each one. That is, when you plan to stat()
		447	all files in the given directory, then the returned order will likely
		448	be fastest.
		449
		450	If both this flag and C<EIO_READDIR_DIRS_FIRST> are specified, then
		451	the likely dirs come first, resulting in a less optimal stat order.
		452
		453	=item EIO_READDIR_FOUND_UNKNOWN
		454
		455	This flag should not be specified when calling C<eio_readdir>. Instead,
		456	it is being set by C<eio_readdir> (you can access the C<flags> via C<<
		457	req->int1 >>, when any of the C<type>'s found were C<EIO_DT_UNKNOWN>. The
		458	absense of this flag therefore indicates that all C<type>'s are known,
		459	which can be used to speed up some algorithms.
		460
		461	A typical use case would be to identify all subdirectories within a
		462	directory - you would ask C<eio_readdir> for C<EIO_READDIR_DIRS_FIRST>. If
		463	then this flag is I<NOT> set, then all the entries at the beginning of the
		464	returned array of type C<EIO_DT_DIR> are the directories. Otherwise, you
		465	should start C<stat()>'ing the entries starting at the beginning of the
		466	array, stopping as soon as you found all directories (the count can be
		467	deduced by the link count of the directory).
		468
		469	=back
		470
		471	=back
		472
		473	=head3 OS-SPECIFIC CALL WRAPPERS
		474
		475	These wrap OS-specific calls (usually Linux ones), and might or might not
		476	be emulated on other operating systems. Calls that are not emulated will
		477	return C<-1> and set C<errno> to C<ENOSYS>.
		478
		479	=over 4
		480
		481	=item eio_sendfile (int out_fd, int in_fd, off_t in_offset, size_t length, int pri, eio_cb cb, void *data)
		482
		483	Wraps the C<sendfile> syscall. The arguments follow the Linux version, but
		484	libeio supports and will use similar calls on FreeBSD, HP/UX, Solaris and
		485	Darwin.
		486
		487	If the OS doesn't support some sendfile-like call, or the call fails,
		488	indicating support for the given file descriptor type (for example,
		489	Linux's sendfile might not support file to file copies), then libeio will
		490	emulate the call in userspace, so there are almost no limitations on its
		491	use.
		492
		493	=item eio_readahead (int fd, off_t offset, size_t length, int pri, eio_cb cb, void *data)
		494
		495	Calls C<readahead(2)>. If the syscall is missing, then the call is
		496	emulated by simply reading the data (currently in 64kiB chunks).
		497
		498	=item eio_sync_file_range (int fd, off_t offset, size_t nbytes, unsigned int flags, int pri, eio_cb cb, void *data)
		499
		500	Calls C<sync_file_range>. If the syscall is missing, then this is the same
		501	as calling C<fdatasync>.
		502
		503	Flags can be any combination of C<EIO_SYNC_FILE_RANGE_WAIT_BEFORE>,
		504	C<EIO_SYNC_FILE_RANGE_WRITE> and C<EIO_SYNC_FILE_RANGE_WAIT_AFTER>.
		505
		506	=back
		507
		508	=head3 LIBEIO-SPECIFIC REQUESTS
		509
		510	These requests are specific to libeio and do not correspond to any OS call.
		511
		512	=over 4
		513
		514	=item eio_mtouch (void addr, size_t length, int flags, int pri, eio_cb cb, void data)
		515
		516	Reads (C<flags == 0>) or modifies (C<flags == EIO_MT_MODIFY) the given
		517	memory area, page-wise, that is, it reads (or reads and writes back) the
		518	first octet of every page that spans the memory area.
		519
		520	This can be used to page in some mmapped file, or dirty some pages. Note
		521	that dirtying is an unlocked read-write access, so races can ensue when
		522	the some other thread modifies the data stored in that memory area.
		523
		524	=item eio_custom (void ()(eio_req ) execute, int pri, eio_cb cb, void *data)
		525
		526	Executes a custom request, i.e., a user-specified callback.
		527
		528	The callback gets the C<eio_req *> as parameter and is expected to read
		529	and modify any request-specific members. Specifically, it should set C<<
		530	req->result >> to the result value, just like other requests.
		531
		532	Here is an example that simply calls C<open>, like C<eio_open>, but it
		533	uses the C<data> member as filename and uses a hardcoded C<O_RDONLY>. If
		534	you want to pass more/other parameters, you either need to pass some
		535	struct or so via C<data> or provide your own wrapper using the low-level
		536	API.
		537
		538	static int
		539	my_open_done (eio_req *req)
		540	{
		541	int fd = req->result;
		542
		543	return 0;
		544	}
		545
		546	static void
		547	my_open (eio_req *req)
		548	{
		549	req->result = open (req->data, O_RDONLY);
		550	}
		551
		552	eio_custom (my_open, 0, my_open_done, "/etc/passwd");
		553
		554	=item eio_busy (eio_tstamp delay, int pri, eio_cb cb, void *data)
		555
		556	This is a a request that takes C<delay> seconds to execute, but otherwise
		557	does nothing - it simply puts one of the worker threads to sleep for this
		558	long.
		559
		560	This request can be used to artificially increase load, e.g. for debugging
		561	or benchmarking reasons.
		562
		563	=item eio_nop (int pri, eio_cb cb, void *data)
		564
		565	This request does nothing, except go through the whole request cycle. This
		566	can be used to measure latency or in some cases to simplify code, but is
		567	not really of much use.
		568
		569	=back
		570
		571	=head3 GROUPING AND LIMITING REQUESTS
		572
		573	#TODO
		574
		575	/*****************************************************************************/
		576	/* groups */
		577
		578	eio_req eio_grp (eio_cb cb, void data);
		579	void eio_grp_feed (eio_req grp, void (feed)(eio_req *req), int limit);
		580	void eio_grp_limit (eio_req *grp, int limit);
		581	void eio_grp_add (eio_req grp, eio_req req);
		582	void eio_grp_cancel (eio_req grp); / cancels all sub requests but not the group */
		583
		584
		585	=back
		586
		587
		588	=head1 LOW LEVEL REQUEST API
		589
		590	#TODO
		591
		592
		593	=head1 ANATOMY AND LIFETIME OF AN EIO REQUEST
		594
		595	A request is represented by a structure of type C<eio_req>. To initialise
		596	it, clear it to all zero bytes:
		597
		598	eio_req req;
		599
		600	memset (&req, 0, sizeof (req));
		601
		602	A more common way to initialise a new C<eio_req> is to use C<calloc>:
		603
		604	eio_req req = calloc (1, sizeof (req));
		605
		606	In either case, libeio neither allocates, initialises or frees the
		607	C<eio_req> structure for you - it merely uses it.
		608
		609	zero
		610
		611	#TODO
		612
138	=head2 CONFIGURATION	613	=head2 CONFIGURATION
139		614
140	The functions in this section can sometimes be useful, but the default	615	The functions in this section can sometimes be useful, but the default
141	configuration will do in most case, so you should skip this section on	616	configuration will do in most case, so you should skip this section on
142	first reading.	617	first reading.
…		…
185	=item eio_set_max_idle (unsigned int nthreads)	660	=item eio_set_max_idle (unsigned int nthreads)
186		661
187	Libeio uses threads internally to handle most requests, and will start and stop threads on demand.	662	Libeio uses threads internally to handle most requests, and will start and stop threads on demand.
188		663
189	This call can be used to limit the number of idle threads (threads without	664	This call can be used to limit the number of idle threads (threads without
190	work to do): libeio will keep some threads idle in preperation for more	665	work to do): libeio will keep some threads idle in preparation for more
191	requests, but never longer than C<nthreads> threads.	666	requests, but never longer than C<nthreads> threads.
192		667
193	In addition to this, libeio will also stop threads when they are idle for	668	In addition to this, libeio will also stop threads when they are idle for
194	a few seconds, regardless of this setting.	669	a few seconds, regardless of this setting.
195		670
…		…
213	Returns the number of pending requests, i.e. requests that have been	688	Returns the number of pending requests, i.e. requests that have been
214	executed and have results, but have not been finished yet by a call to	689	executed and have results, but have not been finished yet by a call to
215	C<eio_poll>).	690	C<eio_poll>).
216		691
217	=back	692	=back
218
219
220	=head1 ANATOMY OF AN EIO REQUEST
221
222	#TODO
223
224
225	=head1 HIGH LEVEL REQUEST API
226
227	#TODO
228
229	=back
230
231
232	=head1 LOW LEVEL REQUEST API
233
234	#TODO
235		693
236	=head1 EMBEDDING	694	=head1 EMBEDDING
237		695
238	Libeio can be embedded directly into programs. This functionality is not	696	Libeio can be embedded directly into programs. This functionality is not
239	documented and not (yet) officially supported.	697	documented and not (yet) officially supported.

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Comparing libeio/eio.pod (file contents): Revision 1.4 by root, Wed Apr 22 11:04:49 2009 UTC vs. Revision 1.10 by root, Sun Jun 5 23:22:04 2011 UTC

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Comparing libeio/eio.pod (file contents):
Revision 1.4 by root, Wed Apr 22 11:04:49 2009 UTC vs.
Revision 1.10 by root, Sun Jun 5 23:22:04 2011 UTC