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

Comparing IO-AIO/README (file contents):
Revision 1.21 by root, Fri Dec 22 04:05:50 2006 UTC vs.
Revision 1.46 by root, Sun Mar 27 10:26:08 2011 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::idle_timeout $seconds
		210	IO::AIO::max_outstanding $maxreqs
		211	IO::AIO::nreqs
		212	IO::AIO::nready
		213	IO::AIO::npending
		214
		215	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		216	IO::AIO::fadvise $fh, $offset, $len, $advice
		217	IO::AIO::madvise $scalar, $offset, $length, $advice
		218	IO::AIO::mprotect $scalar, $offset, $length, $protect
		219	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		220	IO::AIO::munlockall
		221
173	AIO REQUEST FUNCTIONS	222	AIO REQUEST FUNCTIONS
174	All the "aio_*" calls are more or less thin wrappers around the syscall	223	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	224	with the same name (sans "aio_"). The arguments are similar or
176	identical, and they all accept an additional (and optional) $callback	225	identical, and they all accept an additional (and optional) $callback
177	argument which must be a code reference. This code reference will get	226	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	227	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	228	error, unlike perl, which usually delivers "false") as its sole argument
180	argument when the given syscall has been executed asynchronously.	229	after the given syscall has been executed asynchronously.
181		230
182	All functions expecting a filehandle keep a copy of the filehandle	231	All functions expecting a filehandle keep a copy of the filehandle
183	internally until the request has finished.	232	internally until the request has finished.
184		233
185	All functions return request objects of type IO::AIO::REQ that allow	234	All functions return request objects of type IO::AIO::REQ that allow
…		…
198	the user environment, d) use Glib::filename_from_unicode on unicode	247	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	248	filenames or e) use something else to ensure your scalar has the correct
200	contents.	249	contents.
201		250
202	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	251	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
203	handles correctly wether it is set or not.	252	handles correctly whether it is set or not.
204		253
205	$prev_pri = aioreq_pri [$pri]	254	$prev_pri = aioreq_pri [$pri]
206	Returns the priority value that would be used for the next request	255	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.	256	and, if $pri is given, sets the priority for the next aio request.
208		257
…		…
242	They are the same as used by "sysopen".	291	They are the same as used by "sysopen".
243		292
244	Likewise, $mode specifies the mode of the newly created file, if it	293	Likewise, $mode specifies the mode of the newly created file, if it
245	didn't exist and "O_CREAT" has been given, just like perl's	294	didn't exist and "O_CREAT" has been given, just like perl's
246	"sysopen", except that it is mandatory (i.e. use 0 if you don't	295	"sysopen", except that it is mandatory (i.e. use 0 if you don't
247	create new files, and 0666 or 0777 if you do).	296	create new files, and 0666 or 0777 if you do). Note that the $mode
		297	will be modified by the umask in effect then the request is being
		298	executed, so better never change the umask.
248		299
249	Example:	300	Example:
250		301
251	aio_open "/etc/passwd", O_RDONLY, 0, sub {	302	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
252	if ($_[0]) {	303	if ($_[0]) {
253	print "open successful, fh is $_[0]\n";	304	print "open successful, fh is $_[0]\n";
254	...	305	...
255	} else {	306	} else {
256	die "open failed: $!\n";	307	die "open failed: $!\n";
257	}	308	}
258	};	309	};
259		310
260	aio_close $fh, $callback->($status)	311	aio_close $fh, $callback->($status)
261	Asynchronously close a file and call the callback with the result	312	Asynchronously close a file and call the callback with the result
262	code. WARNING: although accepted, you should not pass in a perl	313	code.
263	filehandle here, as perl will likely close the file descriptor
264	another time when the filehandle is destroyed. Normally, you can
265	safely call perls "close" or just let filehandles go out of scope.
266		314
267	This is supposed to be a bug in the API, so that might change. It's	315	Unfortunately, you can't do this to perl. Perl insists very
268	therefore best to avoid this function.	316	strongly on closing the file descriptor associated with the
		317	filehandle itself.
		318
		319	Therefore, "aio_close" will not close the filehandle - instead it
		320	will use dup2 to overwrite the file descriptor with the write-end of
		321	a pipe (the pipe fd will be created on demand and will be cached).
		322
		323	Or in other words: the file descriptor will be closed, but it will
		324	not be free for reuse until the perl filehandle is closed.
269		325
270	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	326	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
271	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	327	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
272	Reads or writes "length" bytes from the specified "fh" and "offset"	328	Reads or writes $length bytes from or to the specified $fh and
273	into the scalar given by "data" and offset "dataoffset" and calls	329	$offset into the scalar given by $data and offset $dataoffset and
274	the callback without the actual number of bytes read (or -1 on	330	calls the callback without the actual number of bytes read (or -1 on
275	error, just like the syscall).	331	error, just like the syscall).
276		332
		333	"aio_read" will, like "sysread", shrink or grow the $data scalar to
		334	offset plus the actual number of bytes read.
		335
		336	If $offset is undefined, then the current file descriptor offset
		337	will be used (and updated), otherwise the file descriptor offset
		338	will not be changed by these calls.
		339
		340	If $length is undefined in "aio_write", use the remaining length of
		341	$data.
		342
		343	If $dataoffset is less than zero, it will be counted from the end of
		344	$data.
		345
277	The $data scalar MUST NOT be modified in any way while the request	346	The $data scalar MUST NOT be modified in any way while the request
278	is outstanding. Modifying it can result in segfaults or WW3 (if the	347	is outstanding. Modifying it can result in segfaults or World War
279	necessary/optional hardware is installed).	348	III (if the necessary/optional hardware is installed).
280		349
281	Example: Read 15 bytes at offset 7 into scalar $buffer, starting at	350	Example: Read 15 bytes at offset 7 into scalar $buffer, starting at
282	offset 0 within the scalar:	351	offset 0 within the scalar:
283		352
284	aio_read $fh, 7, 15, $buffer, 0, sub {	353	aio_read $fh, 7, 15, $buffer, 0, sub {
…		…
291	reading at byte offset $in_offset, and starts writing at the current	360	reading at byte offset $in_offset, and starts writing at the current
292	file offset of $out_fh. Because of that, it is not safe to issue	361	file offset of $out_fh. Because of that, it is not safe to issue
293	more than one "aio_sendfile" per $out_fh, as they will interfere	362	more than one "aio_sendfile" per $out_fh, as they will interfere
294	with each other.	363	with each other.
295		364
		365	Please note that "aio_sendfile" can read more bytes from $in_fh than
		366	are written, and there is no way to find out how many bytes have
		367	been read from "aio_sendfile" alone, as "aio_sendfile" only provides
		368	the number of bytes written to $out_fh. Only if the result value
		369	equals $length one can assume that $length bytes have been read.
		370
		371	Unlike with other "aio_" functions, it makes a lot of sense to use
		372	"aio_sendfile" on non-blocking sockets, as long as one end
		373	(typically the $in_fh) is a file - the file I/O will then be
		374	asynchronous, while the socket I/O will be non-blocking. Note,
		375	however, that you can run into a trap where "aio_sendfile" reads
		376	some data with readahead, then fails to write all data, and when the
		377	socket is ready the next time, the data in the cache is already
		378	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		379	"aio_read" + "aio_write" let's you control resource usage much
		380	better.
		381
296	This call tries to make use of a native "sendfile" syscall to	382	This call tries to make use of a native "sendfile" syscall to
297	provide zero-copy operation. For this to work, $out_fh should refer	383	provide zero-copy operation. For this to work, $out_fh should refer
298	to a socket, and $in_fh should refer to mmap'able file.	384	to a socket, and $in_fh should refer to an mmap'able file.
299		385
300	If the native sendfile call fails or is not implemented, it will be	386	If a native sendfile cannot be found or it fails with "ENOSYS",
		387	"ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",
301	emulated, so you can call "aio_sendfile" on any type of filehandle	388	it will be emulated, so you can call "aio_sendfile" on any type of
302	regardless of the limitations of the operating system.	389	filehandle regardless of the limitations of the operating system.
303
304	Please note, however, that "aio_sendfile" can read more bytes from
305	$in_fh than are written, and there is no way to find out how many
306	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"
307	only provides the number of bytes written to $out_fh. Only if the
308	result value equals $length one can assume that $length bytes have
309	been read.
310		390
311	aio_readahead $fh,$offset,$length, $callback->($retval)	391	aio_readahead $fh,$offset,$length, $callback->($retval)
312	"aio_readahead" populates the page cache with data from a file so	392	"aio_readahead" populates the page cache with data from a file so
313	that subsequent reads from that file will not block on disk I/O. The	393	that subsequent reads from that file will not block on disk I/O. The
314	$offset argument specifies the starting point from which data is to	394	$offset argument specifies the starting point from which data is to
…		…
335	Currently, the stats are always 64-bit-stats, i.e. instead of	415	Currently, the stats are always 64-bit-stats, i.e. instead of
336	returning an error when stat'ing a large file, the results will be	416	returning an error when stat'ing a large file, the results will be
337	silently truncated unless perl itself is compiled with large file	417	silently truncated unless perl itself is compiled with large file
338	support.	418	support.
339		419
		420	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		421	the following constants and functions (if not implemented, the
		422	constants will be 0 and the functions will either "croak" or fall
		423	back on traditional behaviour).
		424
		425	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		426	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		427	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		428
340	Example: Print the length of /etc/passwd:	429	Example: Print the length of /etc/passwd:
341		430
342	aio_stat "/etc/passwd", sub {	431	aio_stat "/etc/passwd", sub {
343	$_[0] and die "stat failed: $!";	432	$_[0] and die "stat failed: $!";
344	print "size is ", -s _, "\n";	433	print "size is ", -s _, "\n";
345	};	434	};
346		435
		436	aio_statvfs $fh_or_path, $callback->($statvfs)
		437	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		438	whether a file handle or path was passed.
		439
		440	On success, the callback is passed a hash reference with the
		441	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		442	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		443	failure, "undef" is passed.
		444
		445	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		446	and "ST_NOSUID".
		447
		448	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		449	their correct value when available, or to 0 on systems that do not
		450	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		451	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		452	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		453
		454	Example: stat "/wd" and dump out the data if successful.
		455
		456	aio_statvfs "/wd", sub {
		457	my $f = $_[0]
		458	or die "statvfs: $!";
		459
		460	use Data::Dumper;
		461	say Dumper $f;
		462	};
		463
		464	# result:
		465	{
		466	bsize => 1024,
		467	bfree => 4333064312,
		468	blocks => 10253828096,
		469	files => 2050765568,
		470	flag => 4096,
		471	favail => 2042092649,
		472	bavail => 4333064312,
		473	ffree => 2042092649,
		474	namemax => 255,
		475	frsize => 1024,
		476	fsid => 1810
		477	}
		478
		479	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		480	Works like perl's "utime" function (including the special case of
		481	$atime and $mtime being undef). Fractional times are supported if
		482	the underlying syscalls support them.
		483
		484	When called with a pathname, uses utimes(2) if available, otherwise
		485	utime(2). If called on a file descriptor, uses futimes(2) if
		486	available, otherwise returns ENOSYS, so this is not portable.
		487
		488	Examples:
		489
		490	# set atime and mtime to current time (basically touch(1)):
		491	aio_utime "path", undef, undef;
		492	# set atime to current time and mtime to beginning of the epoch:
		493	aio_utime "path", time, undef; # undef==0
		494
		495	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		496	Works like perl's "chown" function, except that "undef" for either
		497	$uid or $gid is being interpreted as "do not change" (but -1 can
		498	also be used).
		499
		500	Examples:
		501
		502	# same as "chown root path" in the shell:
		503	aio_chown "path", 0, -1;
		504	# same as above:
		505	aio_chown "path", 0, undef;
		506
		507	aio_truncate $fh_or_path, $offset, $callback->($status)
		508	Works like truncate(2) or ftruncate(2).
		509
		510	aio_chmod $fh_or_path, $mode, $callback->($status)
		511	Works like perl's "chmod" function.
		512
347	aio_unlink $pathname, $callback->($status)	513	aio_unlink $pathname, $callback->($status)
348	Asynchronously unlink (delete) a file and call the callback with the	514	Asynchronously unlink (delete) a file and call the callback with the
349	result code.	515	result code.
350		516
351	aio_mknod $path, $mode, $dev, $callback->($status)	517	aio_mknod $path, $mode, $dev, $callback->($status)
…		…
354	Asynchronously create a device node (or fifo). See mknod(2).	520	Asynchronously create a device node (or fifo). See mknod(2).
355		521
356	The only (POSIX-) portable way of calling this function is:	522	The only (POSIX-) portable way of calling this function is:
357		523
358	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	524	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		525
		526	See "aio_stat" for info about some potentially helpful extra
		527	constants and functions.
359		528
360	aio_link $srcpath, $dstpath, $callback->($status)	529	aio_link $srcpath, $dstpath, $callback->($status)
361	Asynchronously create a new link to the existing object at $srcpath	530	Asynchronously create a new link to the existing object at $srcpath
362	at the path $dstpath and call the callback with the result code.	531	at the path $dstpath and call the callback with the result code.
363		532
…		…
373		542
374	aio_rename $srcpath, $dstpath, $callback->($status)	543	aio_rename $srcpath, $dstpath, $callback->($status)
375	Asynchronously rename the object at $srcpath to $dstpath, just as	544	Asynchronously rename the object at $srcpath to $dstpath, just as
376	rename(2) and call the callback with the result code.	545	rename(2) and call the callback with the result code.
377		546
		547	aio_mkdir $pathname, $mode, $callback->($status)
		548	Asynchronously mkdir (create) a directory and call the callback with
		549	the result code. $mode will be modified by the umask at the time the
		550	request is executed, so do not change your umask.
		551
378	aio_rmdir $pathname, $callback->($status)	552	aio_rmdir $pathname, $callback->($status)
379	Asynchronously rmdir (delete) a directory and call the callback with	553	Asynchronously rmdir (delete) a directory and call the callback with
380	the result code.	554	the result code.
381		555
382	aio_readdir $pathname, $callback->($entries)	556	aio_readdir $pathname, $callback->($entries)
383	Unlike the POSIX call of the same name, "aio_readdir" reads an	557	Unlike the POSIX call of the same name, "aio_readdir" reads an
384	entire directory (i.e. opendir + readdir + closedir). The entries	558	entire directory (i.e. opendir + readdir + closedir). The entries
385	will not be sorted, and will NOT include the "." and ".." entries.	559	will not be sorted, and will NOT include the "." and ".." entries.
386		560
387	The callback a single argument which is either "undef" or an	561	The callback is passed a single argument which is either "undef" or
388	array-ref with the filenames.	562	an array-ref with the filenames.
		563
		564	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		565	Quite similar to "aio_readdir", but the $flags argument allows to
		566	tune behaviour and output format. In case of an error, $entries will
		567	be "undef".
		568
		569	The flags are a combination of the following constants, ORed
		570	together (the flags will also be passed to the callback, possibly
		571	modified):
		572
		573	IO::AIO::READDIR_DENTS
		574	When this flag is off, then the callback gets an arrayref with
		575	of names only (as with "aio_readdir"), otherwise it gets an
		576	arrayref with "[$name, $type, $inode]" arrayrefs, each
		577	describing a single directory entry in more detail.
		578
		579	$name is the name of the entry.
		580
		581	$type is one of the "IO::AIO::DT_xxx" constants:
		582
		583	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
		584	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
		585	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
		586
		587	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
		588	you need to know, you have to run stat yourself. Also, for speed
		589	reasons, the $type scalars are read-only: you can not modify
		590	them.
		591
		592	$inode is the inode number (which might not be exact on systems
		593	with 64 bit inode numbers and 32 bit perls). This field has
		594	unspecified content on systems that do not deliver the inode
		595	information.
		596
		597	IO::AIO::READDIR_DIRS_FIRST
		598	When this flag is set, then the names will be returned in an
		599	order where likely directories come first. This is useful when
		600	you need to quickly find directories, or you want to find all
		601	directories while avoiding to stat() each entry.
		602
		603	If the system returns type information in readdir, then this is
		604	used to find directories directly. Otherwise, likely directories
		605	are files beginning with ".", or otherwise files with no dots,
		606	of which files with short names are tried first.
		607
		608	IO::AIO::READDIR_STAT_ORDER
		609	When this flag is set, then the names will be returned in an
		610	order suitable for stat()'ing each one. That is, when you plan
		611	to stat() all files in the given directory, then the returned
		612	order will likely be fastest.
		613
		614	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
		615	specified, then the likely dirs come first, resulting in a less
		616	optimal stat order.
		617
		618	IO::AIO::READDIR_FOUND_UNKNOWN
		619	This flag should not be set when calling "aio_readdirx".
		620	Instead, it is being set by "aio_readdirx", when any of the
		621	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this
		622	flag therefore indicates that all $type's are known, which can
		623	be used to speed up some algorithms.
		624
		625	aio_load $path, $data, $callback->($status)
		626	This is a composite request that tries to fully load the given file
		627	into memory. Status is the same as with aio_read.
389		628
390	aio_copy $srcpath, $dstpath, $callback->($status)	629	aio_copy $srcpath, $dstpath, $callback->($status)
391	Try to copy the file (directories not supported as either source	630	Try to copy the file (directories not supported as either source
392	or destination) from $srcpath to $dstpath and call the callback with	631	or destination) from $srcpath to $dstpath and call the callback with
393	the 0 (error) or -1 ok.	632	a status of 0 (ok) or -1 (error, see $!).
394		633
395	This is a composite request that it creates the destination file	634	This is a composite request that creates the destination file with
396	with mode 0200 and copies the contents of the source file into it	635	mode 0200 and copies the contents of the source file into it using
397	using "aio_sendfile", followed by restoring atime, mtime, access	636	"aio_sendfile", followed by restoring atime, mtime, access mode and
398	mode and uid/gid, in that order.	637	uid/gid, in that order.
399		638
400	If an error occurs, the partial destination file will be unlinked,	639	If an error occurs, the partial destination file will be unlinked,
401	if possible, except when setting atime, mtime, access mode and	640	if possible, except when setting atime, mtime, access mode and
402	uid/gid, where errors are being ignored.	641	uid/gid, where errors are being ignored.
403		642
404	aio_move $srcpath, $dstpath, $callback->($status)	643	aio_move $srcpath, $dstpath, $callback->($status)
405	Try to move the file (directories not supported as either source	644	Try to move the file (directories not supported as either source
406	or destination) from $srcpath to $dstpath and call the callback with	645	or destination) from $srcpath to $dstpath and call the callback with
407	the 0 (error) or -1 ok.	646	a status of 0 (ok) or -1 (error, see $!).
408		647
409	This is a composite request that tries to rename(2) the file first.	648	This is a composite request that tries to rename(2) the file first;
410	If rename files with "EXDEV", it copies the file with "aio_copy"	649	if rename fails with "EXDEV", it copies the file with "aio_copy"
411	and, if that is successful, unlinking the $srcpath.	650	and, if that is successful, unlinks the $srcpath.
412		651
413	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	652	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
414	Scans a directory (similar to "aio_readdir") but additionally tries	653	Scans a directory (similar to "aio_readdir") but additionally tries
415	to efficiently separate the entries of directory $path into two sets	654	to efficiently separate the entries of directory $path into two sets
416	of names, directories you can recurse into (directories), and ones	655	of names, directories you can recurse into (directories), and ones
…		…
436	Implementation notes.	675	Implementation notes.
437		676
438	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry	677	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
439	can.	678	can.
440		679
		680	If readdir returns file type information, then this is used directly
		681	to find directories.
		682
441	After reading the directory, the modification time, size etc. of the	683	Otherwise, after reading the directory, the modification time, size
442	directory before and after the readdir is checked, and if they match	684	etc. of the directory before and after the readdir is checked, and
443	(and isn't the current time), the link count will be used to decide	685	if they match (and isn't the current time), the link count will be
444	how many entries are directories (if >= 2). Otherwise, no knowledge	686	used to decide how many entries are directories (if >= 2).
445	of the number of subdirectories will be assumed.	687	Otherwise, no knowledge of the number of subdirectories will be
		688	assumed.
446		689
447	Then entries will be sorted into likely directories (everything	690	Then entries will be sorted into likely directories a non-initial
448	without a non-initial dot currently) and likely non-directories	691	dot currently) and likely non-directories (see "aio_readdirx"). Then
449	(everything else). Then every entry plus an appended "/." will be	692	every entry plus an appended "/." will be "stat"'ed, likely
450	"stat"'ed, likely directories first. If that succeeds, it assumes	693	directories first, in order of their inode numbers. If that
451	that the entry is a directory or a symlink to directory (which will	694	succeeds, it assumes that the entry is a directory or a symlink to
452	be checked seperately). This is often faster than stat'ing the entry	695	directory (which will be checked seperately). This is often faster
453	itself because filesystems might detect the type of the entry	696	than stat'ing the entry itself because filesystems might detect the
454	without reading the inode data (e.g. ext2fs filetype feature).	697	type of the entry without reading the inode data (e.g. ext2fs
		698	filetype feature), even on systems that cannot return the filetype
		699	information on readdir.
455		700
456	If the known number of directories (link count - 2) has been	701	If the known number of directories (link count - 2) has been
457	reached, the rest of the entries is assumed to be non-directories.	702	reached, the rest of the entries is assumed to be non-directories.
458		703
459	This only works with certainty on POSIX (= UNIX) filesystems, which	704	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
461		706
462	It will also likely work on non-POSIX filesystems with reduced	707	It will also likely work on non-POSIX filesystems with reduced
463	efficiency as those tend to return 0 or 1 as link counts, which	708	efficiency as those tend to return 0 or 1 as link counts, which
464	disables the directory counting heuristic.	709	disables the directory counting heuristic.
465		710
		711	aio_rmtree $path, $callback->($status)
		712	Delete a directory tree starting (and including) $path, return the
		713	status of the final "rmdir" only. This is a composite request that
		714	uses "aio_scandir" to recurse into and rmdir directories, and unlink
		715	everything else.
		716
		717	aio_sync $callback->($status)
		718	Asynchronously call sync and call the callback when finished.
		719
466	aio_fsync $fh, $callback->($status)	720	aio_fsync $fh, $callback->($status)
467	Asynchronously call fsync on the given filehandle and call the	721	Asynchronously call fsync on the given filehandle and call the
468	callback with the fsync result code.	722	callback with the fsync result code.
469		723
470	aio_fdatasync $fh, $callback->($status)	724	aio_fdatasync $fh, $callback->($status)
471	Asynchronously call fdatasync on the given filehandle and call the	725	Asynchronously call fdatasync on the given filehandle and call the
472	callback with the fdatasync result code.	726	callback with the fdatasync result code.
473		727
474	If this call isn't available because your OS lacks it or it couldn't	728	If this call isn't available because your OS lacks it or it couldn't
475	be detected, it will be emulated by calling "fsync" instead.	729	be detected, it will be emulated by calling "fsync" instead.
		730
		731	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		732	Sync the data portion of the file specified by $offset and $length
		733	to disk (but NOT the metadata), by calling the Linux-specific
		734	sync_file_range call. If sync_file_range is not available or it
		735	returns ENOSYS, then fdatasync or fsync is being substituted.
		736
		737	$flags can be a combination of
		738	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
		739	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
		740	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
		741	manpage for details.
		742
		743	aio_pathsync $path, $callback->($status)
		744	This request tries to open, fsync and close the given path. This is
		745	a composite request intended to sync directories after directory
		746	operations (E.g. rename). This might not work on all operating
		747	systems or have any specific effect, but usually it makes sure that
		748	directory changes get written to disc. It works for anything that
		749	can be opened for read-only, not just directories.
		750
		751	Future versions of this function might fall back to other methods
		752	when "fsync" on the directory fails (such as calling "sync").
		753
		754	Passes 0 when everything went ok, and -1 on error.
		755
		756	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		757	$callback->($status)
		758	This is a rather advanced IO::AIO call, which only works on
		759	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		760	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		761	note that the scalar must only be modified in-place while an aio
		762	operation is pending on it).
		763
		764	It calls the "msync" function of your OS, if available, with the
		765	memory area starting at $offset in the string and ending $length
		766	bytes later. If $length is negative, counts from the end, and if
		767	$length is "undef", then it goes till the end of the string. The
		768	flags can be a combination of "IO::AIO::MS_ASYNC",
		769	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		770
		771	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		772	$callback->($status)
		773	This is a rather advanced IO::AIO call, which works best on
		774	mmap(2)ed scalars.
		775
		776	It touches (reads or writes) all memory pages in the specified range
		777	inside the scalar. All caveats and parameters are the same as for
		778	"aio_msync", above, except for flags, which must be either 0 (which
		779	reads all pages and ensures they are instantiated) or
		780	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		781	and writing an octet from it, which dirties the page).
		782
		783	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		784	This is a rather advanced IO::AIO call, which works best on
		785	mmap(2)ed scalars.
		786
		787	It reads in all the pages of the underlying storage into memory (if
		788	any) and locks them, so they are not getting swapped/paged out or
		789	removed.
		790
		791	If $length is undefined, then the scalar will be locked till the
		792	end.
		793
		794	On systems that do not implement "mlock", this function returns -1
		795	and sets errno to "ENOSYS".
		796
		797	Note that the corresponding "munlock" is synchronous and is
		798	documented under "MISCELLANEOUS FUNCTIONS".
		799
		800	Example: open a file, mmap and mlock it - both will be undone when
		801	$data gets destroyed.
		802
		803	open my $fh, "<", $path or die "$path: $!";
		804	my $data;
		805	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		806	aio_mlock $data; # mlock in background
		807
		808	aio_mlockall $flags, $callback->($status)
		809	Calls the "mlockall" function with the given $flags (a combination
		810	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		811
		812	On systems that do not implement "mlockall", this function returns
		813	-1 and sets errno to "ENOSYS".
		814
		815	Note that the corresponding "munlockall" is synchronous and is
		816	documented under "MISCELLANEOUS FUNCTIONS".
		817
		818	Example: asynchronously lock all current and future pages into
		819	memory.
		820
		821	aio_mlockall IO::AIO::MCL_FUTURE;
476		822
477	aio_group $callback->(...)	823	aio_group $callback->(...)
478	This is a very special aio request: Instead of doing something, it	824	This is a very special aio request: Instead of doing something, it
479	is a container for other aio requests, which is useful if you want	825	is a container for other aio requests, which is useful if you want
480	to bundle many requests into a single, composite, request with a	826	to bundle many requests into a single, composite, request with a
…		…
523		869
524	cancel $req	870	cancel $req
525	Cancels the request, if possible. Has the effect of skipping	871	Cancels the request, if possible. Has the effect of skipping
526	execution when entering the execute state and skipping calling the	872	execution when entering the execute state and skipping calling the
527	callback when entering the the result state, but will leave the	873	callback when entering the the result state, but will leave the
528	request otherwise untouched. That means that requests that currently	874	request otherwise untouched (with the exception of readdir). That
529	execute will not be stopped and resources held by the request will	875	means that requests that currently execute will not be stopped and
530	not be freed prematurely.	876	resources held by the request will not be freed prematurely.
531		877
532	cb $req $callback->(...)	878	cb $req $callback->(...)
533	Replace (or simply set) the callback registered to the request.	879	Replace (or simply set) the callback registered to the request.
534		880
535	IO::AIO::GRP CLASS	881	IO::AIO::GRP CLASS
…		…
562	};	908	};
563		909
564	This makes it very easy to create composite requests (see the source of	910	This makes it very easy to create composite requests (see the source of
565	"aio_move" for an application) that work and feel like simple requests.	911	"aio_move" for an application) that work and feel like simple requests.
566		912
567	* The IO::AIO::GRP objects will be cleaned up during calls to	913	* The IO::AIO::GRP objects will be cleaned up during calls to
568	"IO::AIO::poll_cb", just like any other request.	914	"IO::AIO::poll_cb", just like any other request.
		915
569	* They can be canceled like any other request. Canceling will cancel not	916	* They can be canceled like any other request. Canceling will cancel
570	only the request itself, but also all requests it contains.	917	not only the request itself, but also all requests it contains.
		918
571	* They can also can also be added to other IO::AIO::GRP objects.	919	* They can also can also be added to other IO::AIO::GRP objects.
		920
572	* You must not add requests to a group from within the group callback	921	* You must not add requests to a group from within the group callback
573	(or any later time).	922	(or any later time).
574		923
575	Their lifetime, simplified, looks like this: when they are empty, they	924	Their lifetime, simplified, looks like this: when they are empty, they
576	will finish very quickly. If they contain only requests that are in the	925	will finish very quickly. If they contain only requests that are in the
577	"done" state, they will also finish. Otherwise they will continue to	926	"done" state, they will also finish. Otherwise they will continue to
578	exist.	927	exist.
579		928
580	That means after creating a group you have some time to add requests.	929	That means after creating a group you have some time to add requests
581	And in the callbacks of those requests, you can add further requests to	930	(precisely before the callback has been invoked, which is only done
582	the group. And only when all those requests have finished will the the	931	within the "poll_cb"). And in the callbacks of those requests, you can
583	group itself finish.	932	add further requests to the group. And only when all those requests have
		933	finished will the the group itself finish.
584		934
585	add $grp ...	935	add $grp ...
586	$grp->add (...)	936	$grp->add (...)
587	Add one or more requests to the group. Any type of IO::AIO::REQ can	937	Add one or more requests to the group. Any type of IO::AIO::REQ can
588	be added, including other groups, as long as you do not create	938	be added, including other groups, as long as you do not create
…		…
593	$grp->cancel_subs	943	$grp->cancel_subs
594	Cancel all subrequests and clears any feeder, but not the group	944	Cancel all subrequests and clears any feeder, but not the group
595	request itself. Useful when you queued a lot of events but got a	945	request itself. Useful when you queued a lot of events but got a
596	result early.	946	result early.
597		947
		948	The group request will finish normally (you cannot add requests to
		949	the group).
		950
598	$grp->result (...)	951	$grp->result (...)
599	Set the result value(s) that will be passed to the group callback	952	Set the result value(s) that will be passed to the group callback
600	when all subrequests have finished and set thre groups errno to the	953	when all subrequests have finished and set the groups errno to the
601	current value of errno (just like calling "errno" without an error	954	current value of errno (just like calling "errno" without an error
602	number). By default, no argument will be passed and errno is zero.	955	number). By default, no argument will be passed and errno is zero.
603		956
604	$grp->errno ([$errno])	957	$grp->errno ([$errno])
605	Sets the group errno value to $errno, or the current value of errno	958	Sets the group errno value to $errno, or the current value of errno
…		…
631	does not impose any limits).	984	does not impose any limits).
632		985
633	If the feed does not queue more requests when called, it will be	986	If the feed does not queue more requests when called, it will be
634	automatically removed from the group.	987	automatically removed from the group.
635		988
636	If the feed limit is 0, it will be set to 2 automatically.	989	If the feed limit is 0 when this method is called, it will be set to
		990	2 automatically.
637		991
638	Example:	992	Example:
639		993
640	# stat all files in @files, but only ever use four aio requests concurrently:	994	# stat all files in @files, but only ever use four aio requests concurrently:
641		995
…		…
652	Sets the feeder limit for the group: The feeder will be called	1006	Sets the feeder limit for the group: The feeder will be called
653	whenever the group contains less than this many requests.	1007	whenever the group contains less than this many requests.
654		1008
655	Setting the limit to 0 will pause the feeding process.	1009	Setting the limit to 0 will pause the feeding process.
656		1010
		1011	The default value for the limit is 0, but note that setting a feeder
		1012	automatically bumps it up to 2.
		1013
657	SUPPORT FUNCTIONS	1014	SUPPORT FUNCTIONS
658	EVENT PROCESSING AND EVENT LOOP INTEGRATION	1015	EVENT PROCESSING AND EVENT LOOP INTEGRATION
659	$fileno = IO::AIO::poll_fileno	1016	$fileno = IO::AIO::poll_fileno
660	Return the request result pipe file descriptor. This filehandle	1017	Return the request result pipe file descriptor. This filehandle
661	must be polled for reading by some mechanism outside this module	1018	must be polled for reading by some mechanism outside this module
662	(e.g. Event or select, see below or the SYNOPSIS). If the pipe	1019	(e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
663	becomes readable you have to call "poll_cb" to check the results.	1020	pipe becomes readable you have to call "poll_cb" to check the
		1021	results.
664		1022
665	See "poll_cb" for an example.	1023	See "poll_cb" for an example.
666		1024
667	IO::AIO::poll_cb	1025	IO::AIO::poll_cb
668	Process some outstanding events on the result pipe. You have to call	1026	Process some outstanding events on the result pipe. You have to call
669	this regularly. Returns the number of events processed. Returns	1027	this regularly. Returns 0 if all events could be processed, or -1 if
670	immediately when no events are outstanding. The amount of events	1028	it returned earlier for whatever reason. Returns immediately when no
		1029	events are outstanding. The amount of events processed depends on
671	processed depends on the settings of "IO::AIO::max_poll_req" and	1030	the settings of "IO::AIO::max_poll_req" and
672	"IO::AIO::max_poll_time".	1031	"IO::AIO::max_poll_time".
673		1032
674	If not all requests were processed for whatever reason, the	1033	If not all requests were processed for whatever reason, the
675	filehandle will still be ready when "poll_cb" returns.	1034	filehandle will still be ready when "poll_cb" returns, so normally
		1035	you don't have to do anything special to have it called later.
676		1036
677	Example: Install an Event watcher that automatically calls	1037	Example: Install an Event watcher that automatically calls
678	IO::AIO::poll_cb with high priority:	1038	IO::AIO::poll_cb with high priority (more examples can be found in
		1039	the SYNOPSIS section, at the top of this document):
679		1040
680	Event->io (fd => IO::AIO::poll_fileno,	1041	Event->io (fd => IO::AIO::poll_fileno,
681	poll => 'r', async => 1,	1042	poll => 'r', async => 1,
682	cb => \&IO::AIO::poll_cb);	1043	cb => \&IO::AIO::poll_cb);
		1044
		1045	IO::AIO::poll_wait
		1046	If there are any outstanding requests and none of them in the result
		1047	phase, wait till the result filehandle becomes ready for reading
		1048	(simply does a "select" on the filehandle. This is useful if you
		1049	want to synchronously wait for some requests to finish).
		1050
		1051	See "nreqs" for an example.
		1052
		1053	IO::AIO::poll
		1054	Waits until some requests have been handled.
		1055
		1056	Returns the number of requests processed, but is otherwise strictly
		1057	equivalent to:
		1058
		1059	IO::AIO::poll_wait, IO::AIO::poll_cb
		1060
		1061	IO::AIO::flush
		1062	Wait till all outstanding AIO requests have been handled.
		1063
		1064	Strictly equivalent to:
		1065
		1066	IO::AIO::poll_wait, IO::AIO::poll_cb
		1067	while IO::AIO::nreqs;
683		1068
684	IO::AIO::max_poll_reqs $nreqs	1069	IO::AIO::max_poll_reqs $nreqs
685	IO::AIO::max_poll_time $seconds	1070	IO::AIO::max_poll_time $seconds
686	These set the maximum number of requests (default 0, meaning	1071	These set the maximum number of requests (default 0, meaning
687	infinity) that are being processed by "IO::AIO::poll_cb" in one	1072	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
711	# use a low priority so other tasks have priority	1096	# use a low priority so other tasks have priority
712	Event->io (fd => IO::AIO::poll_fileno,	1097	Event->io (fd => IO::AIO::poll_fileno,
713	poll => 'r', nice => 1,	1098	poll => 'r', nice => 1,
714	cb => &IO::AIO::poll_cb);	1099	cb => &IO::AIO::poll_cb);
715		1100
716	IO::AIO::poll_wait
717	If there are any outstanding requests and none of them in the result
718	phase, wait till the result filehandle becomes ready for reading
719	(simply does a "select" on the filehandle. This is useful if you
720	want to synchronously wait for some requests to finish).
721
722	See "nreqs" for an example.
723
724	IO::AIO::poll
725	Waits until some requests have been handled.
726
727	Returns the number of requests processed, but is otherwise strictly
728	equivalent to:
729
730	IO::AIO::poll_wait, IO::AIO::poll_cb
731
732	IO::AIO::flush
733	Wait till all outstanding AIO requests have been handled.
734
735	Strictly equivalent to:
736
737	IO::AIO::poll_wait, IO::AIO::poll_cb
738	while IO::AIO::nreqs;
739
740	CONTROLLING THE NUMBER OF THREADS	1101	CONTROLLING THE NUMBER OF THREADS
741	IO::AIO::min_parallel $nthreads	1102	IO::AIO::min_parallel $nthreads
742	Set the minimum number of AIO threads to $nthreads. The current	1103	Set the minimum number of AIO threads to $nthreads. The current
743	default is 8, which means eight asynchronous operations can execute	1104	default is 8, which means eight asynchronous operations can execute
744	concurrently at any one time (the number of outstanding requests,	1105	concurrently at any one time (the number of outstanding requests,
…		…
773		1134
774	Under normal circumstances you don't need to call this function.	1135	Under normal circumstances you don't need to call this function.
775		1136
776	IO::AIO::max_idle $nthreads	1137	IO::AIO::max_idle $nthreads
777	Limit the number of threads (default: 4) that are allowed to idle	1138	Limit the number of threads (default: 4) that are allowed to idle
778	(i.e., threads that did not get a request to process within 10	1139	(i.e., threads that did not get a request to process within the idle
779	seconds). That means if a thread becomes idle while $nthreads other	1140	timeout (default: 10 seconds). That means if a thread becomes idle
780	threads are also idle, it will free its resources and exit.	1141	while $nthreads other threads are also idle, it will free its
		1142	resources and exit.
781		1143
782	This is useful when you allow a large number of threads (e.g. 100 or	1144	This is useful when you allow a large number of threads (e.g. 100 or
783	1000) to allow for extremely high load situations, but want to free	1145	1000) to allow for extremely high load situations, but want to free
784	resources under normal circumstances (1000 threads can easily	1146	resources under normal circumstances (1000 threads can easily
785	consume 30MB of RAM).	1147	consume 30MB of RAM).
786		1148
787	The default is probably ok in most situations, especially if thread	1149	The default is probably ok in most situations, especially if thread
788	creation is fast. If thread creation is very slow on your system you	1150	creation is fast. If thread creation is very slow on your system you
789	might want to use larger values.	1151	might want to use larger values.
790		1152
		1153	IO::AIO::idle_timeout $seconds
		1154	Sets the minimum idle timeout (default 10) after which worker
		1155	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1156
791	$oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1157	IO::AIO::max_outstanding $maxreqs
792	This is a very bad function to use in interactive programs because	1158	This is a very bad function to use in interactive programs because
793	it blocks, and a bad way to reduce concurrency because it is	1159	it blocks, and a bad way to reduce concurrency because it is
794	inexact: Better use an "aio_group" together with a feed callback.	1160	inexact: Better use an "aio_group" together with a feed callback.
795		1161
796	Sets the maximum number of outstanding requests to $nreqs. If you to	1162	Sets the maximum number of outstanding requests to $nreqs. If you do
797	queue up more than this number of requests, the next call to the	1163	queue up more than this number of requests, the next call to the
798	"poll_cb" (and "poll_some" and other functions calling "poll_cb")	1164	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
799	function will block until the limit is no longer exceeded.	1165	function will block until the limit is no longer exceeded.
800		1166
801	The default value is very large, so there is no practical limit on	1167	The default value is very large, so there is no practical limit on
802	the number of outstanding requests.	1168	the number of outstanding requests.
803		1169
804	You can still queue as many requests as you want. Therefore,	1170	You can still queue as many requests as you want. Therefore,
805	"max_oustsanding" is mainly useful in simple scripts (with low	1171	"max_outstanding" is mainly useful in simple scripts (with low
806	values) or as a stop gap to shield against fatal memory overflow	1172	values) or as a stop gap to shield against fatal memory overflow
807	(with large values).	1173	(with large values).
808		1174
809	STATISTICAL INFORMATION	1175	STATISTICAL INFORMATION
810	IO::AIO::nreqs	1176	IO::AIO::nreqs
…		…
822	executed).	1188	executed).
823		1189
824	IO::AIO::npending	1190	IO::AIO::npending
825	Returns the number of requests currently in the pending state	1191	Returns the number of requests currently in the pending state
826	(executed, but not yet processed by poll_cb).	1192	(executed, but not yet processed by poll_cb).
		1193
		1194	MISCELLANEOUS FUNCTIONS
		1195	IO::AIO implements some functions that might be useful, but are not
		1196	asynchronous.
		1197
		1198	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1199	Calls the "eio_sendfile_sync" function, which is like
		1200	"aio_sendfile", but is blocking (this makes most sense if you know
		1201	the input data is likely cached already and the output filehandle is
		1202	set to non-blocking operations).
		1203
		1204	Returns the number of bytes copied, or -1 on error.
		1205
		1206	IO::AIO::fadvise $fh, $offset, $len, $advice
		1207	Simply calls the "posix_fadvise" function (see its manpage for
		1208	details). The following advice constants are avaiable:
		1209	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1210	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1211	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1212
		1213	On systems that do not implement "posix_fadvise", this function
		1214	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1215
		1216	IO::AIO::madvise $scalar, $offset, $len, $advice
		1217	Simply calls the "posix_madvise" function (see its manpage for
		1218	details). The following advice constants are avaiable:
		1219	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1220	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1221	"IO::AIO::MADV_DONTNEED".
		1222
		1223	On systems that do not implement "posix_madvise", this function
		1224	returns ENOSYS, otherwise the return value of "posix_madvise".
		1225
		1226	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1227	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1228	$scalar (see its manpage for details). The following protect
		1229	constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1230	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1231
		1232	On systems that do not implement "mprotect", this function returns
		1233	ENOSYS, otherwise the return value of "mprotect".
		1234
		1235	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1236	Memory-maps a file (or anonymous memory range) and attaches it to
		1237	the given $scalar, which will act like a string scalar.
		1238
		1239	The only operations allowed on the scalar are "substr"/"vec" that
		1240	don't change the string length, and most read-only operations such
		1241	as copying it or searching it with regexes and so on.
		1242
		1243	Anything else is unsafe and will, at best, result in memory leaks.
		1244
		1245	The memory map associated with the $scalar is automatically removed
		1246	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1247	"IO::AIO::munmap" functions are called.
		1248
		1249	This calls the "mmap"(2) function internally. See your system's
		1250	manual page for details on the $length, $prot and $flags parameters.
		1251
		1252	The $length must be larger than zero and smaller than the actual
		1253	filesize.
		1254
		1255	$prot is a combination of "IO::AIO::PROT_NONE",
		1256	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1257	"IO::AIO::PROT_WRITE",
		1258
		1259	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1260	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1261	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1262	(which is set to "MAP_ANON" if your system only provides this
		1263	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1264	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1265	"IO::AIO::MAP_NONBLOCK"
		1266
		1267	If $fh is "undef", then a file descriptor of -1 is passed.
		1268
		1269	$offset is the offset from the start of the file - it generally must
		1270	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1271
		1272	Example:
		1273
		1274	use Digest::MD5;
		1275	use IO::AIO;
		1276
		1277	open my $fh, "<verybigfile"
		1278	or die "$!";
		1279
		1280	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1281	or die "verybigfile: $!";
		1282
		1283	my $fast_md5 = md5 $data;
		1284
		1285	IO::AIO::munmap $scalar
		1286	Removes a previous mmap and undefines the $scalar.
		1287
		1288	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1289	Calls the "munlock" function, undoing the effects of a previous
		1290	"aio_mlock" call (see its description for details).
		1291
		1292	IO::AIO::munlockall
		1293	Calls the "munlockall" function.
		1294
		1295	On systems that do not implement "munlockall", this function returns
		1296	ENOSYS, otherwise the return value of "munlockall".
		1297
		1298	EVENT LOOP INTEGRATION
		1299	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1300	automatically into many event loops:
		1301
		1302	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1303	use AnyEvent::AIO;
		1304
		1305	You can also integrate IO::AIO manually into many event loops, here are
		1306	some examples of how to do this:
		1307
		1308	# EV integration
		1309	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1310
		1311	# Event integration
		1312	Event->io (fd => IO::AIO::poll_fileno,
		1313	poll => 'r',
		1314	cb => \&IO::AIO::poll_cb);
		1315
		1316	# Glib/Gtk2 integration
		1317	add_watch Glib::IO IO::AIO::poll_fileno,
		1318	in => sub { IO::AIO::poll_cb; 1 };
		1319
		1320	# Tk integration
		1321	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1322	readable => \&IO::AIO::poll_cb);
		1323
		1324	# Danga::Socket integration
		1325	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1326	\&IO::AIO::poll_cb);
827		1327
828	FORK BEHAVIOUR	1328	FORK BEHAVIOUR
829	This module should do "the right thing" when the process using it forks:	1329	This module should do "the right thing" when the process using it forks:
830		1330
831	Before the fork, IO::AIO enters a quiescent state where no requests can	1331	Before the fork, IO::AIO enters a quiescent state where no requests can
…		…
847	bytes of memory. In addition, stat requests need a stat buffer (possibly	1347	bytes of memory. In addition, stat requests need a stat buffer (possibly
848	a few hundred bytes), readdir requires a result buffer and so on. Perl	1348	a few hundred bytes), readdir requires a result buffer and so on. Perl
849	scalars and other data passed into aio requests will also be locked and	1349	scalars and other data passed into aio requests will also be locked and
850	will consume memory till the request has entered the done state.	1350	will consume memory till the request has entered the done state.
851		1351
852	This is now awfully much, so queuing lots of requests is not usually a	1352	This is not awfully much, so queuing lots of requests is not usually a
853	problem.	1353	problem.
854		1354
855	Per-thread usage:	1355	Per-thread usage:
856		1356
857	In the execution phase, some aio requests require more memory for	1357	In the execution phase, some aio requests require more memory for
…		…
860		1360
861	KNOWN BUGS	1361	KNOWN BUGS
862	Known bugs will be fixed in the next release.	1362	Known bugs will be fixed in the next release.
863		1363
864	SEE ALSO	1364	SEE ALSO
865	Coro::AIO.	1365	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
		1366	more natural syntax.
866		1367
867	AUTHOR	1368	AUTHOR
868	Marc Lehmann <schmorp@schmorp.de>	1369	Marc Lehmann <schmorp@schmorp.de>
869	http://home.schmorp.de/	1370	http://home.schmorp.de/
870		1371

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Comparing IO-AIO/README (file contents): Revision 1.21 by root, Fri Dec 22 04:05:50 2006 UTC vs. Revision 1.46 by root, Sun Mar 27 10:26:08 2011 UTC

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Revision 1.21 by root, Fri Dec 22 04:05:50 2006 UTC vs.
Revision 1.46 by root, Sun Mar 27 10:26:08 2011 UTC