[ViewVC] Diff of: cvs/IO-AIO/README

Comparing IO-AIO/README (file contents):
Revision 1.23 by root, Mon Jan 22 15:59:52 2007 UTC vs.
Revision 1.45 by root, Thu Dec 30 07:19:31 2010 UTC

…		…
2	IO::AIO - Asynchronous Input/Output	2	IO::AIO - Asynchronous Input/Output
3		3
4	SYNOPSIS	4	SYNOPSIS
5	use IO::AIO;	5	use IO::AIO;
6		6
7	aio_open "/etc/passwd", O_RDONLY, 0, sub {	7	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
8	my $fh = shift	8	my $fh = shift
9	or die "/etc/passwd: $!";	9	or die "/etc/passwd: $!";
10	...	10	...
11	};	11	};
12		12
…		…
24	$req->cancel; # cancel request if still in queue	24	$req->cancel; # cancel request if still in queue
25		25
26	my $grp = aio_group sub { print "all stats done\n" };	26	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	27	add $grp aio_stat "..." for ...;
28		28
29	# AnyEvent integration
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32
33	# Event integration
34	Event->io (fd => IO::AIO::poll_fileno,
35	poll => 'r',
36	cb => \&IO::AIO::poll_cb);
37
38	# Glib/Gtk2 integration
39	add_watch Glib::IO IO::AIO::poll_fileno,
40	in => sub { IO::AIO::poll_cb; 1 };
41
42	# Tk integration
43	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
44	readable => \&IO::AIO::poll_cb);
45
46	# Danga::Socket integration
47	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
48	\&IO::AIO::poll_cb);
49
50	DESCRIPTION	29	DESCRIPTION
51	This module implements asynchronous I/O using whatever means your	30	This module implements asynchronous I/O using whatever means your
52	operating system supports.	31	operating system supports. It is implemented as an interface to "libeio"
		32	(<http://software.schmorp.de/pkg/libeio.html>).
53		33
54	Asynchronous means that operations that can normally block your program	34	Asynchronous means that operations that can normally block your program
55	(e.g. reading from disk) will be done asynchronously: the operation will	35	(e.g. reading from disk) will be done asynchronously: the operation will
56	still block, but you can do something else in the meantime. This is	36	still block, but you can do something else in the meantime. This is
57	extremely useful for programs that need to stay interactive even when	37	extremely useful for programs that need to stay interactive even when
…		…
61	faster on a RAID volume or over NFS when you do a number of stat	41	faster on a RAID volume or over NFS when you do a number of stat
62	operations concurrently.	42	operations concurrently.
63		43
64	While most of this works on all types of file descriptors (for example	44	While most of this works on all types of file descriptors (for example
65	sockets), using these functions on file descriptors that support	45	sockets), using these functions on file descriptors that support
66	nonblocking operation (again, sockets, pipes etc.) is very inefficient	46	nonblocking operation (again, sockets, pipes etc.) is very inefficient.
67	or might not work (aio_read fails on sockets/pipes/fifos). Use an event
68	loop for that (such as the Event module): IO::AIO will naturally fit	47	Use an event loop for that (such as the EV module): IO::AIO will
69	into such an event loop itself.	48	naturally fit into such an event loop itself.
70		49
71	In this version, a number of threads are started that execute your	50	In this version, a number of threads are started that execute your
72	requests and signal their completion. You don't need thread support in	51	requests and signal their completion. You don't need thread support in
73	perl, and the threads created by this module will not be visible to	52	perl, and the threads created by this module will not be visible to
74	perl. In the future, this module might make use of the native aio	53	perl. In the future, this module might make use of the native aio
…		…
76	not well-supported or restricted (GNU/Linux doesn't allow them on normal	55	not well-supported or restricted (GNU/Linux doesn't allow them on normal
77	files currently, for example), and they would only support aio_read and	56	files currently, for example), and they would only support aio_read and
78	aio_write, so the remaining functionality would have to be implemented	57	aio_write, so the remaining functionality would have to be implemented
79	using threads anyway.	58	using threads anyway.
80		59
81	Although the module will work with in the presence of other (Perl-)	60	Although the module will work in the presence of other (Perl-) threads,
82	threads, it is currently not reentrant in any way, so use appropriate	61	it is currently not reentrant in any way, so use appropriate locking
83	locking yourself, always call "poll_cb" from within the same thread, or	62	yourself, always call "poll_cb" from within the same thread, or never
84	never call "poll_cb" (or other "aio_" functions) recursively.	63	call "poll_cb" (or other "aio_" functions) recursively.
85		64
86	EXAMPLE	65	EXAMPLE
87	This is a simple example that uses the Event module and loads	66	This is a simple example that uses the EV module and loads /etc/passwd
88	/etc/passwd asynchronously:	67	asynchronously:
89		68
90	use Fcntl;	69	use Fcntl;
91	use Event;	70	use EV;
92	use IO::AIO;	71	use IO::AIO;
93		72
94	# register the IO::AIO callback with Event	73	# register the IO::AIO callback with EV
95	Event->io (fd => IO::AIO::poll_fileno,	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
96	poll => 'r',
97	cb => \&IO::AIO::poll_cb);
98		75
99	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
100	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
101	my $fh = shift	78	my $fh = shift
102	or die "error while opening: $!";	79	or die "error while opening: $!";
103		80
104	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
105	my $size = -s $fh;	82	my $size = -s $fh;
…		…
114		91
115	# file contents now in $contents	92	# file contents now in $contents
116	print $contents;	93	print $contents;
117		94
118	# exit event loop and program	95	# exit event loop and program
119	Event::unloop;	96	EV::unloop;
120	};	97	};
121	};	98	};
122		99
123	# possibly queue up other requests, or open GUI windows,	100	# possibly queue up other requests, or open GUI windows,
124	# check for sockets etc. etc.	101	# check for sockets etc. etc.
125		102
126	# process events as long as there are some:	103	# process events as long as there are some:
127	Event::loop;	104	EV::loop;
128		105
129	REQUEST ANATOMY AND LIFETIME	106	REQUEST ANATOMY AND LIFETIME
130	Every "aio_*" function creates a request. which is a C data structure	107	Every "aio_*" function creates a request. which is a C data structure
131	not directly visible to Perl.	108	not directly visible to Perl.
132		109
…		…
168	anymore (except possibly for the Perl object, but its connection to	145	anymore (except possibly for the Perl object, but its connection to
169	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
170	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
171		148
172	FUNCTIONS	149	FUNCTIONS
		150	QUICK OVERVIEW
		151	This section simply lists the prototypes of the most important functions
		152	for quick reference. See the following sections for function-by-function
		153	documentation.
		154
		155	aio_open $pathname, $flags, $mode, $callback->($fh)
		156	aio_close $fh, $callback->($status)
		157	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		158	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		159	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		160	aio_readahead $fh,$offset,$length, $callback->($retval)
		161	aio_stat $fh_or_path, $callback->($status)
		162	aio_lstat $fh, $callback->($status)
		163	aio_statvfs $fh_or_path, $callback->($statvfs)
		164	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		165	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		166	aio_truncate $fh_or_path, $offset, $callback->($status)
		167	aio_chmod $fh_or_path, $mode, $callback->($status)
		168	aio_unlink $pathname, $callback->($status)
		169	aio_mknod $path, $mode, $dev, $callback->($status)
		170	aio_link $srcpath, $dstpath, $callback->($status)
		171	aio_symlink $srcpath, $dstpath, $callback->($status)
		172	aio_readlink $path, $callback->($link)
		173	aio_rename $srcpath, $dstpath, $callback->($status)
		174	aio_mkdir $pathname, $mode, $callback->($status)
		175	aio_rmdir $pathname, $callback->($status)
		176	aio_readdir $pathname, $callback->($entries)
		177	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		178	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		179	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		180	aio_load $path, $data, $callback->($status)
		181	aio_copy $srcpath, $dstpath, $callback->($status)
		182	aio_move $srcpath, $dstpath, $callback->($status)
		183	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		184	aio_rmtree $path, $callback->($status)
		185	aio_sync $callback->($status)
		186	aio_fsync $fh, $callback->($status)
		187	aio_fdatasync $fh, $callback->($status)
		188	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		189	aio_pathsync $path, $callback->($status)
		190	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		191	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		192	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		193	aio_mlockall $flags, $callback->($status)
		194	aio_group $callback->(...)
		195	aio_nop $callback->()
		196
		197	$prev_pri = aioreq_pri [$pri]
		198	aioreq_nice $pri_adjust
		199
		200	IO::AIO::poll_wait
		201	IO::AIO::poll_cb
		202	IO::AIO::poll
		203	IO::AIO::flush
		204	IO::AIO::max_poll_reqs $nreqs
		205	IO::AIO::max_poll_time $seconds
		206	IO::AIO::min_parallel $nthreads
		207	IO::AIO::max_parallel $nthreads
		208	IO::AIO::max_idle $nthreads
		209	IO::AIO::max_outstanding $maxreqs
		210	IO::AIO::nreqs
		211	IO::AIO::nready
		212	IO::AIO::npending
		213
		214	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		215	IO::AIO::fadvise $fh, $offset, $len, $advice
		216	IO::AIO::madvise $scalar, $offset, $length, $advice
		217	IO::AIO::mprotect $scalar, $offset, $length, $protect
		218	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		219	IO::AIO::munlockall
		220
173	AIO REQUEST FUNCTIONS	221	AIO REQUEST FUNCTIONS
174	All the "aio_*" calls are more or less thin wrappers around the syscall	222	All the "aio_*" calls are more or less thin wrappers around the syscall
175	with the same name (sans "aio_"). The arguments are similar or	223	with the same name (sans "aio_"). The arguments are similar or
176	identical, and they all accept an additional (and optional) $callback	224	identical, and they all accept an additional (and optional) $callback
177	argument which must be a code reference. This code reference will get	225	argument which must be a code reference. This code reference will get
178	called with the syscall return code (e.g. most syscalls return -1 on	226	called with the syscall return code (e.g. most syscalls return -1 on
179	error, unlike perl, which usually delivers "false") as it's sole	227	error, unlike perl, which usually delivers "false") as its sole argument
180	argument when the given syscall has been executed asynchronously.	228	after the given syscall has been executed asynchronously.
181		229
182	All functions expecting a filehandle keep a copy of the filehandle	230	All functions expecting a filehandle keep a copy of the filehandle
183	internally until the request has finished.	231	internally until the request has finished.
184		232
185	All functions return request objects of type IO::AIO::REQ that allow	233	All functions return request objects of type IO::AIO::REQ that allow
…		…
198	the user environment, d) use Glib::filename_from_unicode on unicode	246	the user environment, d) use Glib::filename_from_unicode on unicode
199	filenames or e) use something else to ensure your scalar has the correct	247	filenames or e) use something else to ensure your scalar has the correct
200	contents.	248	contents.
201		249
202	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	250	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
203	handles correctly wether it is set or not.	251	handles correctly whether it is set or not.
204		252
205	$prev_pri = aioreq_pri [$pri]	253	$prev_pri = aioreq_pri [$pri]
206	Returns the priority value that would be used for the next request	254	Returns the priority value that would be used for the next request
207	and, if $pri is given, sets the priority for the next aio request.	255	and, if $pri is given, sets the priority for the next aio request.
208		256
…		…
248	will be modified by the umask in effect then the request is being	296	will be modified by the umask in effect then the request is being
249	executed, so better never change the umask.	297	executed, so better never change the umask.
250		298
251	Example:	299	Example:
252		300
253	aio_open "/etc/passwd", O_RDONLY, 0, sub {	301	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
254	if ($_[0]) {	302	if ($_[0]) {
255	print "open successful, fh is $_[0]\n";	303	print "open successful, fh is $_[0]\n";
256	...	304	...
257	} else {	305	} else {
258	die "open failed: $!\n";	306	die "open failed: $!\n";
259	}	307	}
260	};	308	};
261		309
262	aio_close $fh, $callback->($status)	310	aio_close $fh, $callback->($status)
263	Asynchronously close a file and call the callback with the result	311	Asynchronously close a file and call the callback with the result
264	code. WARNING: although accepted, you should not pass in a perl	312	code.
265	filehandle here, as perl will likely close the file descriptor
266	another time when the filehandle is destroyed. Normally, you can
267	safely call perls "close" or just let filehandles go out of scope.
268		313
269	This is supposed to be a bug in the API, so that might change. It's	314	Unfortunately, you can't do this to perl. Perl insists very
270	therefore best to avoid this function.	315	strongly on closing the file descriptor associated with the
		316	filehandle itself.
		317
		318	Therefore, "aio_close" will not close the filehandle - instead it
		319	will use dup2 to overwrite the file descriptor with the write-end of
		320	a pipe (the pipe fd will be created on demand and will be cached).
		321
		322	Or in other words: the file descriptor will be closed, but it will
		323	not be free for reuse until the perl filehandle is closed.
271		324
272	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
273	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	326	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
274	Reads or writes "length" bytes from the specified "fh" and "offset"	327	Reads or writes $length bytes from or to the specified $fh and
275	into the scalar given by "data" and offset "dataoffset" and calls	328	$offset into the scalar given by $data and offset $dataoffset and
276	the callback without the actual number of bytes read (or -1 on	329	calls the callback without the actual number of bytes read (or -1 on
277	error, just like the syscall).	330	error, just like the syscall).
278		331
		332	"aio_read" will, like "sysread", shrink or grow the $data scalar to
		333	offset plus the actual number of bytes read.
		334
		335	If $offset is undefined, then the current file descriptor offset
		336	will be used (and updated), otherwise the file descriptor offset
		337	will not be changed by these calls.
		338
		339	If $length is undefined in "aio_write", use the remaining length of
		340	$data.
		341
		342	If $dataoffset is less than zero, it will be counted from the end of
		343	$data.
		344
279	The $data scalar MUST NOT be modified in any way while the request	345	The $data scalar MUST NOT be modified in any way while the request
280	is outstanding. Modifying it can result in segfaults or WW3 (if the	346	is outstanding. Modifying it can result in segfaults or World War
281	necessary/optional hardware is installed).	347	III (if the necessary/optional hardware is installed).
282		348
283	Example: Read 15 bytes at offset 7 into scalar $buffer, starting at	349	Example: Read 15 bytes at offset 7 into scalar $buffer, starting at
284	offset 0 within the scalar:	350	offset 0 within the scalar:
285		351
286	aio_read $fh, 7, 15, $buffer, 0, sub {	352	aio_read $fh, 7, 15, $buffer, 0, sub {
…		…
293	reading at byte offset $in_offset, and starts writing at the current	359	reading at byte offset $in_offset, and starts writing at the current
294	file offset of $out_fh. Because of that, it is not safe to issue	360	file offset of $out_fh. Because of that, it is not safe to issue
295	more than one "aio_sendfile" per $out_fh, as they will interfere	361	more than one "aio_sendfile" per $out_fh, as they will interfere
296	with each other.	362	with each other.
297		363
		364	Please note that "aio_sendfile" can read more bytes from $in_fh than
		365	are written, and there is no way to find out how many bytes have
		366	been read from "aio_sendfile" alone, as "aio_sendfile" only provides
		367	the number of bytes written to $out_fh. Only if the result value
		368	equals $length one can assume that $length bytes have been read.
		369
		370	Unlike with other "aio_" functions, it makes a lot of sense to use
		371	"aio_sendfile" on non-blocking sockets, as long as one end
		372	(typically the $in_fh) is a file - the file I/O will then be
		373	asynchronous, while the socket I/O will be non-blocking. Note,
		374	however, that you can run into a trap where "aio_sendfile" reads
		375	some data with readahead, then fails to write all data, and when the
		376	socket is ready the next time, the data in the cache is already
		377	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		378	"aio_read" + "aio_write" let's you control resource usage much
		379	better.
		380
298	This call tries to make use of a native "sendfile" syscall to	381	This call tries to make use of a native "sendfile" syscall to
299	provide zero-copy operation. For this to work, $out_fh should refer	382	provide zero-copy operation. For this to work, $out_fh should refer
300	to a socket, and $in_fh should refer to mmap'able file.	383	to a socket, and $in_fh should refer to an mmap'able file.
301		384
302	If the native sendfile call fails or is not implemented, it will be	385	If a native sendfile cannot be found or it fails with "ENOSYS",
		386	"ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",
303	emulated, so you can call "aio_sendfile" on any type of filehandle	387	it will be emulated, so you can call "aio_sendfile" on any type of
304	regardless of the limitations of the operating system.	388	filehandle regardless of the limitations of the operating system.
305
306	Please note, however, that "aio_sendfile" can read more bytes from
307	$in_fh than are written, and there is no way to find out how many
308	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"
309	only provides the number of bytes written to $out_fh. Only if the
310	result value equals $length one can assume that $length bytes have
311	been read.
312		389
313	aio_readahead $fh,$offset,$length, $callback->($retval)	390	aio_readahead $fh,$offset,$length, $callback->($retval)
314	"aio_readahead" populates the page cache with data from a file so	391	"aio_readahead" populates the page cache with data from a file so
315	that subsequent reads from that file will not block on disk I/O. The	392	that subsequent reads from that file will not block on disk I/O. The
316	$offset argument specifies the starting point from which data is to	393	$offset argument specifies the starting point from which data is to
…		…
344	aio_stat "/etc/passwd", sub {	421	aio_stat "/etc/passwd", sub {
345	$_[0] and die "stat failed: $!";	422	$_[0] and die "stat failed: $!";
346	print "size is ", -s _, "\n";	423	print "size is ", -s _, "\n";
347	};	424	};
348		425
		426	aio_statvfs $fh_or_path, $callback->($statvfs)
		427	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		428	whether a file handle or path was passed.
		429
		430	On success, the callback is passed a hash reference with the
		431	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		432	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		433	failure, "undef" is passed.
		434
		435	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		436	and "ST_NOSUID".
		437
		438	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		439	their correct value when available, or to 0 on systems that do not
		440	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		441	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		442	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		443
		444	Example: stat "/wd" and dump out the data if successful.
		445
		446	aio_statvfs "/wd", sub {
		447	my $f = $_[0]
		448	or die "statvfs: $!";
		449
		450	use Data::Dumper;
		451	say Dumper $f;
		452	};
		453
		454	# result:
		455	{
		456	bsize => 1024,
		457	bfree => 4333064312,
		458	blocks => 10253828096,
		459	files => 2050765568,
		460	flag => 4096,
		461	favail => 2042092649,
		462	bavail => 4333064312,
		463	ffree => 2042092649,
		464	namemax => 255,
		465	frsize => 1024,
		466	fsid => 1810
		467	}
		468
		469	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		470	Works like perl's "utime" function (including the special case of
		471	$atime and $mtime being undef). Fractional times are supported if
		472	the underlying syscalls support them.
		473
		474	When called with a pathname, uses utimes(2) if available, otherwise
		475	utime(2). If called on a file descriptor, uses futimes(2) if
		476	available, otherwise returns ENOSYS, so this is not portable.
		477
		478	Examples:
		479
		480	# set atime and mtime to current time (basically touch(1)):
		481	aio_utime "path", undef, undef;
		482	# set atime to current time and mtime to beginning of the epoch:
		483	aio_utime "path", time, undef; # undef==0
		484
		485	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		486	Works like perl's "chown" function, except that "undef" for either
		487	$uid or $gid is being interpreted as "do not change" (but -1 can
		488	also be used).
		489
		490	Examples:
		491
		492	# same as "chown root path" in the shell:
		493	aio_chown "path", 0, -1;
		494	# same as above:
		495	aio_chown "path", 0, undef;
		496
		497	aio_truncate $fh_or_path, $offset, $callback->($status)
		498	Works like truncate(2) or ftruncate(2).
		499
		500	aio_chmod $fh_or_path, $mode, $callback->($status)
		501	Works like perl's "chmod" function.
		502
349	aio_unlink $pathname, $callback->($status)	503	aio_unlink $pathname, $callback->($status)
350	Asynchronously unlink (delete) a file and call the callback with the	504	Asynchronously unlink (delete) a file and call the callback with the
351	result code.	505	result code.
352		506
353	aio_mknod $path, $mode, $dev, $callback->($status)	507	aio_mknod $path, $mode, $dev, $callback->($status)
…		…
389	aio_readdir $pathname, $callback->($entries)	543	aio_readdir $pathname, $callback->($entries)
390	Unlike the POSIX call of the same name, "aio_readdir" reads an	544	Unlike the POSIX call of the same name, "aio_readdir" reads an
391	entire directory (i.e. opendir + readdir + closedir). The entries	545	entire directory (i.e. opendir + readdir + closedir). The entries
392	will not be sorted, and will NOT include the "." and ".." entries.	546	will not be sorted, and will NOT include the "." and ".." entries.
393		547
394	The callback a single argument which is either "undef" or an	548	The callback is passed a single argument which is either "undef" or
395	array-ref with the filenames.	549	an array-ref with the filenames.
		550
		551	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		552	Quite similar to "aio_readdir", but the $flags argument allows to
		553	tune behaviour and output format. In case of an error, $entries will
		554	be "undef".
		555
		556	The flags are a combination of the following constants, ORed
		557	together (the flags will also be passed to the callback, possibly
		558	modified):
		559
		560	IO::AIO::READDIR_DENTS
		561	When this flag is off, then the callback gets an arrayref with
		562	of names only (as with "aio_readdir"), otherwise it gets an
		563	arrayref with "[$name, $type, $inode]" arrayrefs, each
		564	describing a single directory entry in more detail.
		565
		566	$name is the name of the entry.
		567
		568	$type is one of the "IO::AIO::DT_xxx" constants:
		569
		570	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
		571	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
		572	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
		573
		574	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
		575	you need to know, you have to run stat yourself. Also, for speed
		576	reasons, the $type scalars are read-only: you can not modify
		577	them.
		578
		579	$inode is the inode number (which might not be exact on systems
		580	with 64 bit inode numbers and 32 bit perls). This field has
		581	unspecified content on systems that do not deliver the inode
		582	information.
		583
		584	IO::AIO::READDIR_DIRS_FIRST
		585	When this flag is set, then the names will be returned in an
		586	order where likely directories come first. This is useful when
		587	you need to quickly find directories, or you want to find all
		588	directories while avoiding to stat() each entry.
		589
		590	If the system returns type information in readdir, then this is
		591	used to find directories directly. Otherwise, likely directories
		592	are files beginning with ".", or otherwise files with no dots,
		593	of which files with short names are tried first.
		594
		595	IO::AIO::READDIR_STAT_ORDER
		596	When this flag is set, then the names will be returned in an
		597	order suitable for stat()'ing each one. That is, when you plan
		598	to stat() all files in the given directory, then the returned
		599	order will likely be fastest.
		600
		601	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
		602	specified, then the likely dirs come first, resulting in a less
		603	optimal stat order.
		604
		605	IO::AIO::READDIR_FOUND_UNKNOWN
		606	This flag should not be set when calling "aio_readdirx".
		607	Instead, it is being set by "aio_readdirx", when any of the
		608	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this
		609	flag therefore indicates that all $type's are known, which can
		610	be used to speed up some algorithms.
396		611
397	aio_load $path, $data, $callback->($status)	612	aio_load $path, $data, $callback->($status)
398	This is a composite request that tries to fully load the given file	613	This is a composite request that tries to fully load the given file
399	into memory. Status is the same as with aio_read.	614	into memory. Status is the same as with aio_read.
400		615
401	aio_copy $srcpath, $dstpath, $callback->($status)	616	aio_copy $srcpath, $dstpath, $callback->($status)
402	Try to copy the file (directories not supported as either source	617	Try to copy the file (directories not supported as either source
403	or destination) from $srcpath to $dstpath and call the callback with	618	or destination) from $srcpath to $dstpath and call the callback with
404	the 0 (error) or -1 ok.	619	a status of 0 (ok) or -1 (error, see $!).
405		620
406	This is a composite request that it creates the destination file	621	This is a composite request that creates the destination file with
407	with mode 0200 and copies the contents of the source file into it	622	mode 0200 and copies the contents of the source file into it using
408	using "aio_sendfile", followed by restoring atime, mtime, access	623	"aio_sendfile", followed by restoring atime, mtime, access mode and
409	mode and uid/gid, in that order.	624	uid/gid, in that order.
410		625
411	If an error occurs, the partial destination file will be unlinked,	626	If an error occurs, the partial destination file will be unlinked,
412	if possible, except when setting atime, mtime, access mode and	627	if possible, except when setting atime, mtime, access mode and
413	uid/gid, where errors are being ignored.	628	uid/gid, where errors are being ignored.
414		629
415	aio_move $srcpath, $dstpath, $callback->($status)	630	aio_move $srcpath, $dstpath, $callback->($status)
416	Try to move the file (directories not supported as either source	631	Try to move the file (directories not supported as either source
417	or destination) from $srcpath to $dstpath and call the callback with	632	or destination) from $srcpath to $dstpath and call the callback with
418	the 0 (error) or -1 ok.	633	a status of 0 (ok) or -1 (error, see $!).
419		634
420	This is a composite request that tries to rename(2) the file first.	635	This is a composite request that tries to rename(2) the file first;
421	If rename files with "EXDEV", it copies the file with "aio_copy"	636	if rename fails with "EXDEV", it copies the file with "aio_copy"
422	and, if that is successful, unlinking the $srcpath.	637	and, if that is successful, unlinks the $srcpath.
423		638
424	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	639	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
425	Scans a directory (similar to "aio_readdir") but additionally tries	640	Scans a directory (similar to "aio_readdir") but additionally tries
426	to efficiently separate the entries of directory $path into two sets	641	to efficiently separate the entries of directory $path into two sets
427	of names, directories you can recurse into (directories), and ones	642	of names, directories you can recurse into (directories), and ones
…		…
447	Implementation notes.	662	Implementation notes.
448		663
449	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry	664	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
450	can.	665	can.
451		666
		667	If readdir returns file type information, then this is used directly
		668	to find directories.
		669
452	After reading the directory, the modification time, size etc. of the	670	Otherwise, after reading the directory, the modification time, size
453	directory before and after the readdir is checked, and if they match	671	etc. of the directory before and after the readdir is checked, and
454	(and isn't the current time), the link count will be used to decide	672	if they match (and isn't the current time), the link count will be
455	how many entries are directories (if >= 2). Otherwise, no knowledge	673	used to decide how many entries are directories (if >= 2).
456	of the number of subdirectories will be assumed.	674	Otherwise, no knowledge of the number of subdirectories will be
		675	assumed.
457		676
458	Then entries will be sorted into likely directories (everything	677	Then entries will be sorted into likely directories a non-initial
459	without a non-initial dot currently) and likely non-directories	678	dot currently) and likely non-directories (see "aio_readdirx"). Then
460	(everything else). Then every entry plus an appended "/." will be	679	every entry plus an appended "/." will be "stat"'ed, likely
461	"stat"'ed, likely directories first. If that succeeds, it assumes	680	directories first, in order of their inode numbers. If that
462	that the entry is a directory or a symlink to directory (which will	681	succeeds, it assumes that the entry is a directory or a symlink to
463	be checked seperately). This is often faster than stat'ing the entry	682	directory (which will be checked seperately). This is often faster
464	itself because filesystems might detect the type of the entry	683	than stat'ing the entry itself because filesystems might detect the
465	without reading the inode data (e.g. ext2fs filetype feature).	684	type of the entry without reading the inode data (e.g. ext2fs
		685	filetype feature), even on systems that cannot return the filetype
		686	information on readdir.
466		687
467	If the known number of directories (link count - 2) has been	688	If the known number of directories (link count - 2) has been
468	reached, the rest of the entries is assumed to be non-directories.	689	reached, the rest of the entries is assumed to be non-directories.
469		690
470	This only works with certainty on POSIX (= UNIX) filesystems, which	691	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
478	Delete a directory tree starting (and including) $path, return the	699	Delete a directory tree starting (and including) $path, return the
479	status of the final "rmdir" only. This is a composite request that	700	status of the final "rmdir" only. This is a composite request that
480	uses "aio_scandir" to recurse into and rmdir directories, and unlink	701	uses "aio_scandir" to recurse into and rmdir directories, and unlink
481	everything else.	702	everything else.
482		703
		704	aio_sync $callback->($status)
		705	Asynchronously call sync and call the callback when finished.
		706
483	aio_fsync $fh, $callback->($status)	707	aio_fsync $fh, $callback->($status)
484	Asynchronously call fsync on the given filehandle and call the	708	Asynchronously call fsync on the given filehandle and call the
485	callback with the fsync result code.	709	callback with the fsync result code.
486		710
487	aio_fdatasync $fh, $callback->($status)	711	aio_fdatasync $fh, $callback->($status)
488	Asynchronously call fdatasync on the given filehandle and call the	712	Asynchronously call fdatasync on the given filehandle and call the
489	callback with the fdatasync result code.	713	callback with the fdatasync result code.
490		714
491	If this call isn't available because your OS lacks it or it couldn't	715	If this call isn't available because your OS lacks it or it couldn't
492	be detected, it will be emulated by calling "fsync" instead.	716	be detected, it will be emulated by calling "fsync" instead.
		717
		718	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		719	Sync the data portion of the file specified by $offset and $length
		720	to disk (but NOT the metadata), by calling the Linux-specific
		721	sync_file_range call. If sync_file_range is not available or it
		722	returns ENOSYS, then fdatasync or fsync is being substituted.
		723
		724	$flags can be a combination of
		725	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
		726	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
		727	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
		728	manpage for details.
		729
		730	aio_pathsync $path, $callback->($status)
		731	This request tries to open, fsync and close the given path. This is
		732	a composite request intended to sync directories after directory
		733	operations (E.g. rename). This might not work on all operating
		734	systems or have any specific effect, but usually it makes sure that
		735	directory changes get written to disc. It works for anything that
		736	can be opened for read-only, not just directories.
		737
		738	Future versions of this function might fall back to other methods
		739	when "fsync" on the directory fails (such as calling "sync").
		740
		741	Passes 0 when everything went ok, and -1 on error.
		742
		743	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		744	$callback->($status)
		745	This is a rather advanced IO::AIO call, which only works on
		746	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		747	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		748	note that the scalar must only be modified in-place while an aio
		749	operation is pending on it).
		750
		751	It calls the "msync" function of your OS, if available, with the
		752	memory area starting at $offset in the string and ending $length
		753	bytes later. If $length is negative, counts from the end, and if
		754	$length is "undef", then it goes till the end of the string. The
		755	flags can be a combination of "IO::AIO::MS_ASYNC",
		756	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		757
		758	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		759	$callback->($status)
		760	This is a rather advanced IO::AIO call, which works best on
		761	mmap(2)ed scalars.
		762
		763	It touches (reads or writes) all memory pages in the specified range
		764	inside the scalar. All caveats and parameters are the same as for
		765	"aio_msync", above, except for flags, which must be either 0 (which
		766	reads all pages and ensures they are instantiated) or
		767	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		768	and writing an octet from it, which dirties the page).
		769
		770	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		771	This is a rather advanced IO::AIO call, which works best on
		772	mmap(2)ed scalars.
		773
		774	It reads in all the pages of the underlying storage into memory (if
		775	any) and locks them, so they are not getting swapped/paged out or
		776	removed.
		777
		778	If $length is undefined, then the scalar will be locked till the
		779	end.
		780
		781	On systems that do not implement "mlock", this function returns -1
		782	and sets errno to "ENOSYS".
		783
		784	Note that the corresponding "munlock" is synchronous and is
		785	documented under "MISCELLANEOUS FUNCTIONS".
		786
		787	Example: open a file, mmap and mlock it - both will be undone when
		788	$data gets destroyed.
		789
		790	open my $fh, "<", $path or die "$path: $!";
		791	my $data;
		792	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		793	aio_mlock $data; # mlock in background
		794
		795	aio_mlockall $flags, $callback->($status)
		796	Calls the "mlockall" function with the given $flags (a combination
		797	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		798
		799	On systems that do not implement "mlockall", this function returns
		800	-1 and sets errno to "ENOSYS".
		801
		802	Note that the corresponding "munlockall" is synchronous and is
		803	documented under "MISCELLANEOUS FUNCTIONS".
		804
		805	Example: asynchronously lock all current and future pages into
		806	memory.
		807
		808	aio_mlockall IO::AIO::MCL_FUTURE;
493		809
494	aio_group $callback->(...)	810	aio_group $callback->(...)
495	This is a very special aio request: Instead of doing something, it	811	This is a very special aio request: Instead of doing something, it
496	is a container for other aio requests, which is useful if you want	812	is a container for other aio requests, which is useful if you want
497	to bundle many requests into a single, composite, request with a	813	to bundle many requests into a single, composite, request with a
…		…
540		856
541	cancel $req	857	cancel $req
542	Cancels the request, if possible. Has the effect of skipping	858	Cancels the request, if possible. Has the effect of skipping
543	execution when entering the execute state and skipping calling the	859	execution when entering the execute state and skipping calling the
544	callback when entering the the result state, but will leave the	860	callback when entering the the result state, but will leave the
545	request otherwise untouched. That means that requests that currently	861	request otherwise untouched (with the exception of readdir). That
546	execute will not be stopped and resources held by the request will	862	means that requests that currently execute will not be stopped and
547	not be freed prematurely.	863	resources held by the request will not be freed prematurely.
548		864
549	cb $req $callback->(...)	865	cb $req $callback->(...)
550	Replace (or simply set) the callback registered to the request.	866	Replace (or simply set) the callback registered to the request.
551		867
552	IO::AIO::GRP CLASS	868	IO::AIO::GRP CLASS
…		…
579	};	895	};
580		896
581	This makes it very easy to create composite requests (see the source of	897	This makes it very easy to create composite requests (see the source of
582	"aio_move" for an application) that work and feel like simple requests.	898	"aio_move" for an application) that work and feel like simple requests.
583		899
584	* The IO::AIO::GRP objects will be cleaned up during calls to	900	* The IO::AIO::GRP objects will be cleaned up during calls to
585	"IO::AIO::poll_cb", just like any other request.	901	"IO::AIO::poll_cb", just like any other request.
		902
586	* They can be canceled like any other request. Canceling will cancel not	903	* They can be canceled like any other request. Canceling will cancel
587	only the request itself, but also all requests it contains.	904	not only the request itself, but also all requests it contains.
		905
588	* They can also can also be added to other IO::AIO::GRP objects.	906	* They can also can also be added to other IO::AIO::GRP objects.
		907
589	* You must not add requests to a group from within the group callback	908	* You must not add requests to a group from within the group callback
590	(or any later time).	909	(or any later time).
591		910
592	Their lifetime, simplified, looks like this: when they are empty, they	911	Their lifetime, simplified, looks like this: when they are empty, they
593	will finish very quickly. If they contain only requests that are in the	912	will finish very quickly. If they contain only requests that are in the
594	"done" state, they will also finish. Otherwise they will continue to	913	"done" state, they will also finish. Otherwise they will continue to
595	exist.	914	exist.
596		915
597	That means after creating a group you have some time to add requests.	916	That means after creating a group you have some time to add requests
598	And in the callbacks of those requests, you can add further requests to	917	(precisely before the callback has been invoked, which is only done
599	the group. And only when all those requests have finished will the the	918	within the "poll_cb"). And in the callbacks of those requests, you can
600	group itself finish.	919	add further requests to the group. And only when all those requests have
		920	finished will the the group itself finish.
601		921
602	add $grp ...	922	add $grp ...
603	$grp->add (...)	923	$grp->add (...)
604	Add one or more requests to the group. Any type of IO::AIO::REQ can	924	Add one or more requests to the group. Any type of IO::AIO::REQ can
605	be added, including other groups, as long as you do not create	925	be added, including other groups, as long as you do not create
…		…
610	$grp->cancel_subs	930	$grp->cancel_subs
611	Cancel all subrequests and clears any feeder, but not the group	931	Cancel all subrequests and clears any feeder, but not the group
612	request itself. Useful when you queued a lot of events but got a	932	request itself. Useful when you queued a lot of events but got a
613	result early.	933	result early.
614		934
		935	The group request will finish normally (you cannot add requests to
		936	the group).
		937
615	$grp->result (...)	938	$grp->result (...)
616	Set the result value(s) that will be passed to the group callback	939	Set the result value(s) that will be passed to the group callback
617	when all subrequests have finished and set thre groups errno to the	940	when all subrequests have finished and set the groups errno to the
618	current value of errno (just like calling "errno" without an error	941	current value of errno (just like calling "errno" without an error
619	number). By default, no argument will be passed and errno is zero.	942	number). By default, no argument will be passed and errno is zero.
620		943
621	$grp->errno ([$errno])	944	$grp->errno ([$errno])
622	Sets the group errno value to $errno, or the current value of errno	945	Sets the group errno value to $errno, or the current value of errno
…		…
648	does not impose any limits).	971	does not impose any limits).
649		972
650	If the feed does not queue more requests when called, it will be	973	If the feed does not queue more requests when called, it will be
651	automatically removed from the group.	974	automatically removed from the group.
652		975
653	If the feed limit is 0, it will be set to 2 automatically.	976	If the feed limit is 0 when this method is called, it will be set to
		977	2 automatically.
654		978
655	Example:	979	Example:
656		980
657	# stat all files in @files, but only ever use four aio requests concurrently:	981	# stat all files in @files, but only ever use four aio requests concurrently:
658		982
…		…
669	Sets the feeder limit for the group: The feeder will be called	993	Sets the feeder limit for the group: The feeder will be called
670	whenever the group contains less than this many requests.	994	whenever the group contains less than this many requests.
671		995
672	Setting the limit to 0 will pause the feeding process.	996	Setting the limit to 0 will pause the feeding process.
673		997
		998	The default value for the limit is 0, but note that setting a feeder
		999	automatically bumps it up to 2.
		1000
674	SUPPORT FUNCTIONS	1001	SUPPORT FUNCTIONS
675	EVENT PROCESSING AND EVENT LOOP INTEGRATION	1002	EVENT PROCESSING AND EVENT LOOP INTEGRATION
676	$fileno = IO::AIO::poll_fileno	1003	$fileno = IO::AIO::poll_fileno
677	Return the request result pipe file descriptor. This filehandle	1004	Return the request result pipe file descriptor. This filehandle
678	must be polled for reading by some mechanism outside this module	1005	must be polled for reading by some mechanism outside this module
679	(e.g. Event or select, see below or the SYNOPSIS). If the pipe	1006	(e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
680	becomes readable you have to call "poll_cb" to check the results.	1007	pipe becomes readable you have to call "poll_cb" to check the
		1008	results.
681		1009
682	See "poll_cb" for an example.	1010	See "poll_cb" for an example.
683		1011
684	IO::AIO::poll_cb	1012	IO::AIO::poll_cb
685	Process some outstanding events on the result pipe. You have to call	1013	Process some outstanding events on the result pipe. You have to call
686	this regularly. Returns the number of events processed. Returns	1014	this regularly. Returns 0 if all events could be processed, or -1 if
687	immediately when no events are outstanding. The amount of events	1015	it returned earlier for whatever reason. Returns immediately when no
		1016	events are outstanding. The amount of events processed depends on
688	processed depends on the settings of "IO::AIO::max_poll_req" and	1017	the settings of "IO::AIO::max_poll_req" and
689	"IO::AIO::max_poll_time".	1018	"IO::AIO::max_poll_time".
690		1019
691	If not all requests were processed for whatever reason, the	1020	If not all requests were processed for whatever reason, the
692	filehandle will still be ready when "poll_cb" returns.	1021	filehandle will still be ready when "poll_cb" returns, so normally
		1022	you don't have to do anything special to have it called later.
693		1023
694	Example: Install an Event watcher that automatically calls	1024	Example: Install an Event watcher that automatically calls
695	IO::AIO::poll_cb with high priority:	1025	IO::AIO::poll_cb with high priority (more examples can be found in
		1026	the SYNOPSIS section, at the top of this document):
696		1027
697	Event->io (fd => IO::AIO::poll_fileno,	1028	Event->io (fd => IO::AIO::poll_fileno,
698	poll => 'r', async => 1,	1029	poll => 'r', async => 1,
699	cb => \&IO::AIO::poll_cb);	1030	cb => \&IO::AIO::poll_cb);
		1031
		1032	IO::AIO::poll_wait
		1033	If there are any outstanding requests and none of them in the result
		1034	phase, wait till the result filehandle becomes ready for reading
		1035	(simply does a "select" on the filehandle. This is useful if you
		1036	want to synchronously wait for some requests to finish).
		1037
		1038	See "nreqs" for an example.
		1039
		1040	IO::AIO::poll
		1041	Waits until some requests have been handled.
		1042
		1043	Returns the number of requests processed, but is otherwise strictly
		1044	equivalent to:
		1045
		1046	IO::AIO::poll_wait, IO::AIO::poll_cb
		1047
		1048	IO::AIO::flush
		1049	Wait till all outstanding AIO requests have been handled.
		1050
		1051	Strictly equivalent to:
		1052
		1053	IO::AIO::poll_wait, IO::AIO::poll_cb
		1054	while IO::AIO::nreqs;
700		1055
701	IO::AIO::max_poll_reqs $nreqs	1056	IO::AIO::max_poll_reqs $nreqs
702	IO::AIO::max_poll_time $seconds	1057	IO::AIO::max_poll_time $seconds
703	These set the maximum number of requests (default 0, meaning	1058	These set the maximum number of requests (default 0, meaning
704	infinity) that are being processed by "IO::AIO::poll_cb" in one	1059	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
728	# use a low priority so other tasks have priority	1083	# use a low priority so other tasks have priority
729	Event->io (fd => IO::AIO::poll_fileno,	1084	Event->io (fd => IO::AIO::poll_fileno,
730	poll => 'r', nice => 1,	1085	poll => 'r', nice => 1,
731	cb => &IO::AIO::poll_cb);	1086	cb => &IO::AIO::poll_cb);
732		1087
733	IO::AIO::poll_wait
734	If there are any outstanding requests and none of them in the result
735	phase, wait till the result filehandle becomes ready for reading
736	(simply does a "select" on the filehandle. This is useful if you
737	want to synchronously wait for some requests to finish).
738
739	See "nreqs" for an example.
740
741	IO::AIO::poll
742	Waits until some requests have been handled.
743
744	Returns the number of requests processed, but is otherwise strictly
745	equivalent to:
746
747	IO::AIO::poll_wait, IO::AIO::poll_cb
748
749	IO::AIO::flush
750	Wait till all outstanding AIO requests have been handled.
751
752	Strictly equivalent to:
753
754	IO::AIO::poll_wait, IO::AIO::poll_cb
755	while IO::AIO::nreqs;
756
757	CONTROLLING THE NUMBER OF THREADS	1088	CONTROLLING THE NUMBER OF THREADS
758	IO::AIO::min_parallel $nthreads	1089	IO::AIO::min_parallel $nthreads
759	Set the minimum number of AIO threads to $nthreads. The current	1090	Set the minimum number of AIO threads to $nthreads. The current
760	default is 8, which means eight asynchronous operations can execute	1091	default is 8, which means eight asynchronous operations can execute
761	concurrently at any one time (the number of outstanding requests,	1092	concurrently at any one time (the number of outstanding requests,
…		…
803		1134
804	The default is probably ok in most situations, especially if thread	1135	The default is probably ok in most situations, especially if thread
805	creation is fast. If thread creation is very slow on your system you	1136	creation is fast. If thread creation is very slow on your system you
806	might want to use larger values.	1137	might want to use larger values.
807		1138
808	$oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1139	IO::AIO::max_outstanding $maxreqs
809	This is a very bad function to use in interactive programs because	1140	This is a very bad function to use in interactive programs because
810	it blocks, and a bad way to reduce concurrency because it is	1141	it blocks, and a bad way to reduce concurrency because it is
811	inexact: Better use an "aio_group" together with a feed callback.	1142	inexact: Better use an "aio_group" together with a feed callback.
812		1143
813	Sets the maximum number of outstanding requests to $nreqs. If you to	1144	Sets the maximum number of outstanding requests to $nreqs. If you do
814	queue up more than this number of requests, the next call to the	1145	queue up more than this number of requests, the next call to the
815	"poll_cb" (and "poll_some" and other functions calling "poll_cb")	1146	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
816	function will block until the limit is no longer exceeded.	1147	function will block until the limit is no longer exceeded.
817		1148
818	The default value is very large, so there is no practical limit on	1149	The default value is very large, so there is no practical limit on
819	the number of outstanding requests.	1150	the number of outstanding requests.
820		1151
821	You can still queue as many requests as you want. Therefore,	1152	You can still queue as many requests as you want. Therefore,
822	"max_oustsanding" is mainly useful in simple scripts (with low	1153	"max_outstanding" is mainly useful in simple scripts (with low
823	values) or as a stop gap to shield against fatal memory overflow	1154	values) or as a stop gap to shield against fatal memory overflow
824	(with large values).	1155	(with large values).
825		1156
826	STATISTICAL INFORMATION	1157	STATISTICAL INFORMATION
827	IO::AIO::nreqs	1158	IO::AIO::nreqs
…		…
839	executed).	1170	executed).
840		1171
841	IO::AIO::npending	1172	IO::AIO::npending
842	Returns the number of requests currently in the pending state	1173	Returns the number of requests currently in the pending state
843	(executed, but not yet processed by poll_cb).	1174	(executed, but not yet processed by poll_cb).
		1175
		1176	MISCELLANEOUS FUNCTIONS
		1177	IO::AIO implements some functions that might be useful, but are not
		1178	asynchronous.
		1179
		1180	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1181	Calls the "eio_sendfile_sync" function, which is like
		1182	"aio_sendfile", but is blocking (this makes most sense if you know
		1183	the input data is likely cached already and the output filehandle is
		1184	set to non-blocking operations).
		1185
		1186	Returns the number of bytes copied, or -1 on error.
		1187
		1188	IO::AIO::fadvise $fh, $offset, $len, $advice
		1189	Simply calls the "posix_fadvise" function (see its manpage for
		1190	details). The following advice constants are avaiable:
		1191	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1192	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1193	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1194
		1195	On systems that do not implement "posix_fadvise", this function
		1196	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1197
		1198	IO::AIO::madvise $scalar, $offset, $len, $advice
		1199	Simply calls the "posix_madvise" function (see its manpage for
		1200	details). The following advice constants are avaiable:
		1201	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1202	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1203	"IO::AIO::MADV_DONTNEED".
		1204
		1205	On systems that do not implement "posix_madvise", this function
		1206	returns ENOSYS, otherwise the return value of "posix_madvise".
		1207
		1208	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1209	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1210	$scalar (see its manpage for details). The following protect
		1211	constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1212	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1213
		1214	On systems that do not implement "mprotect", this function returns
		1215	ENOSYS, otherwise the return value of "mprotect".
		1216
		1217	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1218	Memory-maps a file (or anonymous memory range) and attaches it to
		1219	the given $scalar, which will act like a string scalar.
		1220
		1221	The only operations allowed on the scalar are "substr"/"vec" that
		1222	don't change the string length, and most read-only operations such
		1223	as copying it or searching it with regexes and so on.
		1224
		1225	Anything else is unsafe and will, at best, result in memory leaks.
		1226
		1227	The memory map associated with the $scalar is automatically removed
		1228	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1229	"IO::AIO::munmap" functions are called.
		1230
		1231	This calls the "mmap"(2) function internally. See your system's
		1232	manual page for details on the $length, $prot and $flags parameters.
		1233
		1234	The $length must be larger than zero and smaller than the actual
		1235	filesize.
		1236
		1237	$prot is a combination of "IO::AIO::PROT_NONE",
		1238	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1239	"IO::AIO::PROT_WRITE",
		1240
		1241	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1242	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1243	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1244	(which is set to "MAP_ANON" if your system only provides this
		1245	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1246	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1247	"IO::AIO::MAP_NONBLOCK"
		1248
		1249	If $fh is "undef", then a file descriptor of -1 is passed.
		1250
		1251	$offset is the offset from the start of the file - it generally must
		1252	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1253
		1254	Example:
		1255
		1256	use Digest::MD5;
		1257	use IO::AIO;
		1258
		1259	open my $fh, "<verybigfile"
		1260	or die "$!";
		1261
		1262	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1263	or die "verybigfile: $!";
		1264
		1265	my $fast_md5 = md5 $data;
		1266
		1267	IO::AIO::munmap $scalar
		1268	Removes a previous mmap and undefines the $scalar.
		1269
		1270	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1271	Calls the "munlock" function, undoing the effects of a previous
		1272	"aio_mlock" call (see its description for details).
		1273
		1274	IO::AIO::munlockall
		1275	Calls the "munlockall" function.
		1276
		1277	On systems that do not implement "munlockall", this function returns
		1278	ENOSYS, otherwise the return value of "munlockall".
		1279
		1280	EVENT LOOP INTEGRATION
		1281	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1282	automatically into many event loops:
		1283
		1284	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1285	use AnyEvent::AIO;
		1286
		1287	You can also integrate IO::AIO manually into many event loops, here are
		1288	some examples of how to do this:
		1289
		1290	# EV integration
		1291	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1292
		1293	# Event integration
		1294	Event->io (fd => IO::AIO::poll_fileno,
		1295	poll => 'r',
		1296	cb => \&IO::AIO::poll_cb);
		1297
		1298	# Glib/Gtk2 integration
		1299	add_watch Glib::IO IO::AIO::poll_fileno,
		1300	in => sub { IO::AIO::poll_cb; 1 };
		1301
		1302	# Tk integration
		1303	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1304	readable => \&IO::AIO::poll_cb);
		1305
		1306	# Danga::Socket integration
		1307	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1308	\&IO::AIO::poll_cb);
844		1309
845	FORK BEHAVIOUR	1310	FORK BEHAVIOUR
846	This module should do "the right thing" when the process using it forks:	1311	This module should do "the right thing" when the process using it forks:
847		1312
848	Before the fork, IO::AIO enters a quiescent state where no requests can	1313	Before the fork, IO::AIO enters a quiescent state where no requests can
…		…
864	bytes of memory. In addition, stat requests need a stat buffer (possibly	1329	bytes of memory. In addition, stat requests need a stat buffer (possibly
865	a few hundred bytes), readdir requires a result buffer and so on. Perl	1330	a few hundred bytes), readdir requires a result buffer and so on. Perl
866	scalars and other data passed into aio requests will also be locked and	1331	scalars and other data passed into aio requests will also be locked and
867	will consume memory till the request has entered the done state.	1332	will consume memory till the request has entered the done state.
868		1333
869	This is now awfully much, so queuing lots of requests is not usually a	1334	This is not awfully much, so queuing lots of requests is not usually a
870	problem.	1335	problem.
871		1336
872	Per-thread usage:	1337	Per-thread usage:
873		1338
874	In the execution phase, some aio requests require more memory for	1339	In the execution phase, some aio requests require more memory for
…		…
877		1342
878	KNOWN BUGS	1343	KNOWN BUGS
879	Known bugs will be fixed in the next release.	1344	Known bugs will be fixed in the next release.
880		1345
881	SEE ALSO	1346	SEE ALSO
882	Coro::AIO.	1347	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
		1348	more natural syntax.
883		1349
884	AUTHOR	1350	AUTHOR
885	Marc Lehmann <schmorp@schmorp.de>	1351	Marc Lehmann <schmorp@schmorp.de>
886	http://home.schmorp.de/	1352	http://home.schmorp.de/
887		1353

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Comparing IO-AIO/README (file contents): Revision 1.23 by root, Mon Jan 22 15:59:52 2007 UTC vs. Revision 1.45 by root, Thu Dec 30 07:19:31 2010 UTC

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Comparing IO-AIO/README (file contents):
Revision 1.23 by root, Mon Jan 22 15:59:52 2007 UTC vs.
Revision 1.45 by root, Thu Dec 30 07:19:31 2010 UTC