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

Comparing IO-AIO/README (file contents):
Revision 1.29 by root, Wed Apr 16 16:45:30 2008 UTC vs.
Revision 1.48 by root, Wed Jun 29 11:25:17 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 (EV, Event, Glib, Tk, urxvt, pureperl...)
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	# EV integration
34	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
35
36	# Event integration
37	Event->io (fd => IO::AIO::poll_fileno,
38	poll => 'r',
39	cb => \&IO::AIO::poll_cb);
40
41	# Glib/Gtk2 integration
42	add_watch Glib::IO IO::AIO::poll_fileno,
43	in => sub { IO::AIO::poll_cb; 1 };
44
45	# Tk integration
46	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
47	readable => \&IO::AIO::poll_cb);
48
49	# Danga::Socket integration
50	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
51	\&IO::AIO::poll_cb);
52
53	DESCRIPTION	29	DESCRIPTION
54	This module implements asynchronous I/O using whatever means your	30	This module implements asynchronous I/O using whatever means your
55	operating system supports.	31	operating system supports. It is implemented as an interface to "libeio"
		32	(<http://software.schmorp.de/pkg/libeio.html>).
56		33
57	Asynchronous means that operations that can normally block your program	34	Asynchronous means that operations that can normally block your program
58	(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
59	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
60	extremely useful for programs that need to stay interactive even when	37	extremely useful for programs that need to stay interactive even when
…		…
65	operations concurrently.	42	operations concurrently.
66		43
67	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
68	sockets), using these functions on file descriptors that support	45	sockets), using these functions on file descriptors that support
69	nonblocking operation (again, sockets, pipes etc.) is very inefficient.	46	nonblocking operation (again, sockets, pipes etc.) is very inefficient.
70	Use an event loop for that (such as the Event module): IO::AIO will	47	Use an event loop for that (such as the EV module): IO::AIO will
71	naturally fit into such an event loop itself.	48	naturally fit into such an event loop itself.
72		49
73	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
74	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
75	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
…		…
84	it is currently not reentrant in any way, so use appropriate locking	61	it is currently not reentrant in any way, so use appropriate locking
85	yourself, always call "poll_cb" from within the same thread, or never	62	yourself, always call "poll_cb" from within the same thread, or never
86	call "poll_cb" (or other "aio_" functions) recursively.	63	call "poll_cb" (or other "aio_" functions) recursively.
87		64
88	EXAMPLE	65	EXAMPLE
89	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
90	/etc/passwd asynchronously:	67	asynchronously:
91		68
92	use Fcntl;	69	use Fcntl;
93	use Event;	70	use EV;
94	use IO::AIO;	71	use IO::AIO;
95		72
96	# register the IO::AIO callback with Event	73	# register the IO::AIO callback with EV
97	Event->io (fd => IO::AIO::poll_fileno,	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98	poll => 'r',
99	cb => \&IO::AIO::poll_cb);
100		75
101	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
102	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
103	my $fh = shift	78	my $fh = shift
104	or die "error while opening: $!";	79	or die "error while opening: $!";
105		80
106	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
107	my $size = -s $fh;	82	my $size = -s $fh;
…		…
116		91
117	# file contents now in $contents	92	# file contents now in $contents
118	print $contents;	93	print $contents;
119		94
120	# exit event loop and program	95	# exit event loop and program
121	Event::unloop;	96	EV::unloop;
122	};	97	};
123	};	98	};
124		99
125	# possibly queue up other requests, or open GUI windows,	100	# possibly queue up other requests, or open GUI windows,
126	# check for sockets etc. etc.	101	# check for sockets etc. etc.
127		102
128	# process events as long as there are some:	103	# process events as long as there are some:
129	Event::loop;	104	EV::loop;
130		105
131	REQUEST ANATOMY AND LIFETIME	106	REQUEST ANATOMY AND LIFETIME
132	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
133	not directly visible to Perl.	108	not directly visible to Perl.
134		109
…		…
170	anymore (except possibly for the Perl object, but its connection to	145	anymore (except possibly for the Perl object, but its connection to
171	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
172	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
173		148
174	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
175	AIO REQUEST FUNCTIONS	222	AIO REQUEST FUNCTIONS
176	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
177	with the same name (sans "aio_"). The arguments are similar or	224	with the same name (sans "aio_"). The arguments are similar or
178	identical, and they all accept an additional (and optional) $callback	225	identical, and they all accept an additional (and optional) $callback
179	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
180	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
181	error, unlike perl, which usually delivers "false") as it's sole	228	error, unlike perl, which usually delivers "false") as its sole argument
182	argument when the given syscall has been executed asynchronously.	229	after the given syscall has been executed asynchronously.
183		230
184	All functions expecting a filehandle keep a copy of the filehandle	231	All functions expecting a filehandle keep a copy of the filehandle
185	internally until the request has finished.	232	internally until the request has finished.
186		233
187	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
…		…
200	the user environment, d) use Glib::filename_from_unicode on unicode	247	the user environment, d) use Glib::filename_from_unicode on unicode
201	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
202	contents.	249	contents.
203		250
204	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
205	handles correctly wether it is set or not.	252	handles correctly whether it is set or not.
206		253
207	$prev_pri = aioreq_pri [$pri]	254	$prev_pri = aioreq_pri [$pri]
208	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
209	and, if $pri is given, sets the priority for the next aio request.	256	and, if $pri is given, sets the priority for the next aio request.
210		257
…		…
250	will be modified by the umask in effect then the request is being	297	will be modified by the umask in effect then the request is being
251	executed, so better never change the umask.	298	executed, so better never change the umask.
252		299
253	Example:	300	Example:
254		301
255	aio_open "/etc/passwd", O_RDONLY, 0, sub {	302	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
256	if ($_[0]) {	303	if ($_[0]) {
257	print "open successful, fh is $_[0]\n";	304	print "open successful, fh is $_[0]\n";
258	...	305	...
259	} else {	306	} else {
260	die "open failed: $!\n";	307	die "open failed: $!\n";
261	}	308	}
262	};	309	};
263		310
		311	In addition to all the common open modes/flags ("O_RDONLY",
		312	"O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
		313	"O_APPEND"), the following POSIX and non-POSIX constants are
		314	available (missing ones on your system are, as usual, 0):
		315
		316	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
		317	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
		318	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
		319
264	aio_close $fh, $callback->($status)	320	aio_close $fh, $callback->($status)
265	Asynchronously close a file and call the callback with the result	321	Asynchronously close a file and call the callback with the result
266	code.	322	code.
267		323
268	Unfortunately, you can't do this to perl. Perl insists very	324	Unfortunately, you can't do this to perl. Perl insists very
…		…
276	Or in other words: the file descriptor will be closed, but it will	332	Or in other words: the file descriptor will be closed, but it will
277	not be free for reuse until the perl filehandle is closed.	333	not be free for reuse until the perl filehandle is closed.
278		334
279	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	335	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
280	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	336	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
281	Reads or writes $length bytes from the specified $fh and $offset	337	Reads or writes $length bytes from or to the specified $fh and
282	into the scalar given by $data and offset $dataoffset and calls the	338	$offset into the scalar given by $data and offset $dataoffset and
283	callback without the actual number of bytes read (or -1 on error,	339	calls the callback without the actual number of bytes read (or -1 on
284	just like the syscall).	340	error, just like the syscall).
		341
		342	"aio_read" will, like "sysread", shrink or grow the $data scalar to
		343	offset plus the actual number of bytes read.
285		344
286	If $offset is undefined, then the current file descriptor offset	345	If $offset is undefined, then the current file descriptor offset
287	will be used (and updated), otherwise the file descriptor offset	346	will be used (and updated), otherwise the file descriptor offset
288	will not be changed by these calls.	347	will not be changed by these calls.
289		348
…		…
308	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	367	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
309	Tries to copy $length bytes from $in_fh to $out_fh. It starts	368	Tries to copy $length bytes from $in_fh to $out_fh. It starts
310	reading at byte offset $in_offset, and starts writing at the current	369	reading at byte offset $in_offset, and starts writing at the current
311	file offset of $out_fh. Because of that, it is not safe to issue	370	file offset of $out_fh. Because of that, it is not safe to issue
312	more than one "aio_sendfile" per $out_fh, as they will interfere	371	more than one "aio_sendfile" per $out_fh, as they will interfere
313	with each other.	372	with each other. The same $in_fh works fine though, as this function
		373	does not move or use the file offset of $in_fh.
314		374
		375	Please note that "aio_sendfile" can read more bytes from $in_fh than
		376	are written, and there is no way to find out how many more bytes
		377	have been read from "aio_sendfile" alone, as "aio_sendfile" only
		378	provides the number of bytes written to $out_fh. Only if the result
		379	value equals $length one can assume that $length bytes have been
		380	read.
		381
		382	Unlike with other "aio_" functions, it makes a lot of sense to use
		383	"aio_sendfile" on non-blocking sockets, as long as one end
		384	(typically the $in_fh) is a file - the file I/O will then be
		385	asynchronous, while the socket I/O will be non-blocking. Note,
		386	however, that you can run into a trap where "aio_sendfile" reads
		387	some data with readahead, then fails to write all data, and when the
		388	socket is ready the next time, the data in the cache is already
		389	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		390	"aio_read" + "aio_write" let's you better control resource usage.
		391
315	This call tries to make use of a native "sendfile" syscall to	392	This call tries to make use of a native "sendfile"-like syscall to
316	provide zero-copy operation. For this to work, $out_fh should refer	393	provide zero-copy operation. For this to work, $out_fh should refer
317	to a socket, and $in_fh should refer to mmap'able file.	394	to a socket, and $in_fh should refer to an mmap'able file.
318		395
319	If the native sendfile call fails or is not implemented, it will be	396	If a native sendfile cannot be found or it fails with "ENOSYS",
320	emulated, so you can call "aio_sendfile" on any type of filehandle	397	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
321	regardless of the limitations of the operating system.	398	"ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
		399	any type of filehandle regardless of the limitations of the
		400	operating system.
322		401
323	Please note, however, that "aio_sendfile" can read more bytes from	402	As native sendfile syscalls (as practically any non-POSIX interface
324	$in_fh than are written, and there is no way to find out how many	403	hacked together in a hurry to improve benchmark numbers) tend to be
325	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	404	rather buggy on many systems, this implementation tries to work
326	only provides the number of bytes written to $out_fh. Only if the	405	around some known bugs in Linux and FreeBSD kernels (probably
327	result value equals $length one can assume that $length bytes have	406	others, too), but that might fail, so you really really should check
328	been read.	407	the return value of "aio_sendfile" - fewre bytes than expected might
		408	have been transferred.
329		409
330	aio_readahead $fh,$offset,$length, $callback->($retval)	410	aio_readahead $fh,$offset,$length, $callback->($retval)
331	"aio_readahead" populates the page cache with data from a file so	411	"aio_readahead" populates the page cache with data from a file so
332	that subsequent reads from that file will not block on disk I/O. The	412	that subsequent reads from that file will not block on disk I/O. The
333	$offset argument specifies the starting point from which data is to	413	$offset argument specifies the starting point from which data is to
…		…
354	Currently, the stats are always 64-bit-stats, i.e. instead of	434	Currently, the stats are always 64-bit-stats, i.e. instead of
355	returning an error when stat'ing a large file, the results will be	435	returning an error when stat'ing a large file, the results will be
356	silently truncated unless perl itself is compiled with large file	436	silently truncated unless perl itself is compiled with large file
357	support.	437	support.
358		438
		439	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		440	the following constants and functions (if not implemented, the
		441	constants will be 0 and the functions will either "croak" or fall
		442	back on traditional behaviour).
		443
		444	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		445	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		446	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		447
359	Example: Print the length of /etc/passwd:	448	Example: Print the length of /etc/passwd:
360		449
361	aio_stat "/etc/passwd", sub {	450	aio_stat "/etc/passwd", sub {
362	$_[0] and die "stat failed: $!";	451	$_[0] and die "stat failed: $!";
363	print "size is ", -s _, "\n";	452	print "size is ", -s _, "\n";
364	};	453	};
365		454
		455	aio_statvfs $fh_or_path, $callback->($statvfs)
		456	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		457	whether a file handle or path was passed.
		458
		459	On success, the callback is passed a hash reference with the
		460	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		461	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		462	failure, "undef" is passed.
		463
		464	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		465	and "ST_NOSUID".
		466
		467	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		468	their correct value when available, or to 0 on systems that do not
		469	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		470	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		471	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		472
		473	Example: stat "/wd" and dump out the data if successful.
		474
		475	aio_statvfs "/wd", sub {
		476	my $f = $_[0]
		477	or die "statvfs: $!";
		478
		479	use Data::Dumper;
		480	say Dumper $f;
		481	};
		482
		483	# result:
		484	{
		485	bsize => 1024,
		486	bfree => 4333064312,
		487	blocks => 10253828096,
		488	files => 2050765568,
		489	flag => 4096,
		490	favail => 2042092649,
		491	bavail => 4333064312,
		492	ffree => 2042092649,
		493	namemax => 255,
		494	frsize => 1024,
		495	fsid => 1810
		496	}
		497
366	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	498	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
367	Works like perl's "utime" function (including the special case of	499	Works like perl's "utime" function (including the special case of
368	$atime and $mtime being undef). Fractional times are supported if	500	$atime and $mtime being undef). Fractional times are supported if
369	the underlying syscalls support them.	501	the underlying syscalls support them.
370		502
…		…
408		540
409	The only (POSIX-) portable way of calling this function is:	541	The only (POSIX-) portable way of calling this function is:
410		542
411	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	543	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
412		544
		545	See "aio_stat" for info about some potentially helpful extra
		546	constants and functions.
		547
413	aio_link $srcpath, $dstpath, $callback->($status)	548	aio_link $srcpath, $dstpath, $callback->($status)
414	Asynchronously create a new link to the existing object at $srcpath	549	Asynchronously create a new link to the existing object at $srcpath
415	at the path $dstpath and call the callback with the result code.	550	at the path $dstpath and call the callback with the result code.
416		551
417	aio_symlink $srcpath, $dstpath, $callback->($status)	552	aio_symlink $srcpath, $dstpath, $callback->($status)
…		…
440	aio_readdir $pathname, $callback->($entries)	575	aio_readdir $pathname, $callback->($entries)
441	Unlike the POSIX call of the same name, "aio_readdir" reads an	576	Unlike the POSIX call of the same name, "aio_readdir" reads an
442	entire directory (i.e. opendir + readdir + closedir). The entries	577	entire directory (i.e. opendir + readdir + closedir). The entries
443	will not be sorted, and will NOT include the "." and ".." entries.	578	will not be sorted, and will NOT include the "." and ".." entries.
444		579
445	The callback a single argument which is either "undef" or an	580	The callback is passed a single argument which is either "undef" or
446	array-ref with the filenames.	581	an array-ref with the filenames.
		582
		583	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		584	Quite similar to "aio_readdir", but the $flags argument allows to
		585	tune behaviour and output format. In case of an error, $entries will
		586	be "undef".
		587
		588	The flags are a combination of the following constants, ORed
		589	together (the flags will also be passed to the callback, possibly
		590	modified):
		591
		592	IO::AIO::READDIR_DENTS
		593	When this flag is off, then the callback gets an arrayref
		594	consisting of names only (as with "aio_readdir"), otherwise it
		595	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
		596	describing a single directory entry in more detail.
		597
		598	$name is the name of the entry.
		599
		600	$type is one of the "IO::AIO::DT_xxx" constants:
		601
		602	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
		603	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
		604	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
		605
		606	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
		607	you need to know, you have to run stat yourself. Also, for speed
		608	reasons, the $type scalars are read-only: you can not modify
		609	them.
		610
		611	$inode is the inode number (which might not be exact on systems
		612	with 64 bit inode numbers and 32 bit perls). This field has
		613	unspecified content on systems that do not deliver the inode
		614	information.
		615
		616	IO::AIO::READDIR_DIRS_FIRST
		617	When this flag is set, then the names will be returned in an
		618	order where likely directories come first, in optimal stat
		619	order. This is useful when you need to quickly find directories,
		620	or you want to find all directories while avoiding to stat()
		621	each entry.
		622
		623	If the system returns type information in readdir, then this is
		624	used to find directories directly. Otherwise, likely directories
		625	are names beginning with ".", or otherwise names with no dots,
		626	of which names with short names are tried first.
		627
		628	IO::AIO::READDIR_STAT_ORDER
		629	When this flag is set, then the names will be returned in an
		630	order suitable for stat()'ing each one. That is, when you plan
		631	to stat() all files in the given directory, then the returned
		632	order will likely be fastest.
		633
		634	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
		635	specified, then the likely dirs come first, resulting in a less
		636	optimal stat order.
		637
		638	IO::AIO::READDIR_FOUND_UNKNOWN
		639	This flag should not be set when calling "aio_readdirx".
		640	Instead, it is being set by "aio_readdirx", when any of the
		641	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this
		642	flag therefore indicates that all $type's are known, which can
		643	be used to speed up some algorithms.
447		644
448	aio_load $path, $data, $callback->($status)	645	aio_load $path, $data, $callback->($status)
449	This is a composite request that tries to fully load the given file	646	This is a composite request that tries to fully load the given file
450	into memory. Status is the same as with aio_read.	647	into memory. Status is the same as with aio_read.
451		648
452	aio_copy $srcpath, $dstpath, $callback->($status)	649	aio_copy $srcpath, $dstpath, $callback->($status)
453	Try to copy the file (directories not supported as either source	650	Try to copy the file (directories not supported as either source
454	or destination) from $srcpath to $dstpath and call the callback with	651	or destination) from $srcpath to $dstpath and call the callback with
455	the 0 (error) or -1 ok.	652	a status of 0 (ok) or -1 (error, see $!).
456		653
457	This is a composite request that it creates the destination file	654	This is a composite request that creates the destination file with
458	with mode 0200 and copies the contents of the source file into it	655	mode 0200 and copies the contents of the source file into it using
459	using "aio_sendfile", followed by restoring atime, mtime, access	656	"aio_sendfile", followed by restoring atime, mtime, access mode and
460	mode and uid/gid, in that order.	657	uid/gid, in that order.
461		658
462	If an error occurs, the partial destination file will be unlinked,	659	If an error occurs, the partial destination file will be unlinked,
463	if possible, except when setting atime, mtime, access mode and	660	if possible, except when setting atime, mtime, access mode and
464	uid/gid, where errors are being ignored.	661	uid/gid, where errors are being ignored.
465		662
466	aio_move $srcpath, $dstpath, $callback->($status)	663	aio_move $srcpath, $dstpath, $callback->($status)
467	Try to move the file (directories not supported as either source	664	Try to move the file (directories not supported as either source
468	or destination) from $srcpath to $dstpath and call the callback with	665	or destination) from $srcpath to $dstpath and call the callback with
469	the 0 (error) or -1 ok.	666	a status of 0 (ok) or -1 (error, see $!).
470		667
471	This is a composite request that tries to rename(2) the file first.	668	This is a composite request that tries to rename(2) the file first;
472	If rename files with "EXDEV", it copies the file with "aio_copy"	669	if rename fails with "EXDEV", it copies the file with "aio_copy"
473	and, if that is successful, unlinking the $srcpath.	670	and, if that is successful, unlinks the $srcpath.
474		671
475	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	672	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
476	Scans a directory (similar to "aio_readdir") but additionally tries	673	Scans a directory (similar to "aio_readdir") but additionally tries
477	to efficiently separate the entries of directory $path into two sets	674	to efficiently separate the entries of directory $path into two sets
478	of names, directories you can recurse into (directories), and ones	675	of names, directories you can recurse into (directories), and ones
…		…
498	Implementation notes.	695	Implementation notes.
499		696
500	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry	697	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
501	can.	698	can.
502		699
		700	If readdir returns file type information, then this is used directly
		701	to find directories.
		702
503	After reading the directory, the modification time, size etc. of the	703	Otherwise, after reading the directory, the modification time, size
504	directory before and after the readdir is checked, and if they match	704	etc. of the directory before and after the readdir is checked, and
505	(and isn't the current time), the link count will be used to decide	705	if they match (and isn't the current time), the link count will be
506	how many entries are directories (if >= 2). Otherwise, no knowledge	706	used to decide how many entries are directories (if >= 2).
507	of the number of subdirectories will be assumed.	707	Otherwise, no knowledge of the number of subdirectories will be
		708	assumed.
508		709
509	Then entries will be sorted into likely directories (everything	710	Then entries will be sorted into likely directories a non-initial
510	without a non-initial dot currently) and likely non-directories	711	dot currently) and likely non-directories (see "aio_readdirx"). Then
511	(everything else). Then every entry plus an appended "/." will be	712	every entry plus an appended "/." will be "stat"'ed, likely
512	"stat"'ed, likely directories first. If that succeeds, it assumes	713	directories first, in order of their inode numbers. If that
513	that the entry is a directory or a symlink to directory (which will	714	succeeds, it assumes that the entry is a directory or a symlink to
514	be checked seperately). This is often faster than stat'ing the entry	715	directory (which will be checked seperately). This is often faster
515	itself because filesystems might detect the type of the entry	716	than stat'ing the entry itself because filesystems might detect the
516	without reading the inode data (e.g. ext2fs filetype feature).	717	type of the entry without reading the inode data (e.g. ext2fs
		718	filetype feature), even on systems that cannot return the filetype
		719	information on readdir.
517		720
518	If the known number of directories (link count - 2) has been	721	If the known number of directories (link count - 2) has been
519	reached, the rest of the entries is assumed to be non-directories.	722	reached, the rest of the entries is assumed to be non-directories.
520		723
521	This only works with certainty on POSIX (= UNIX) filesystems, which	724	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
543	callback with the fdatasync result code.	746	callback with the fdatasync result code.
544		747
545	If this call isn't available because your OS lacks it or it couldn't	748	If this call isn't available because your OS lacks it or it couldn't
546	be detected, it will be emulated by calling "fsync" instead.	749	be detected, it will be emulated by calling "fsync" instead.
547		750
		751	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		752	Sync the data portion of the file specified by $offset and $length
		753	to disk (but NOT the metadata), by calling the Linux-specific
		754	sync_file_range call. If sync_file_range is not available or it
		755	returns ENOSYS, then fdatasync or fsync is being substituted.
		756
		757	$flags can be a combination of
		758	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
		759	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
		760	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
		761	manpage for details.
		762
548	aio_pathsync $path, $callback->($status)	763	aio_pathsync $path, $callback->($status)
549	This request tries to open, fsync and close the given path. This is	764	This request tries to open, fsync and close the given path. This is
550	a composite request intended tosync directories after directory	765	a composite request intended to sync directories after directory
551	operations (E.g. rename). This might not work on all operating	766	operations (E.g. rename). This might not work on all operating
552	systems or have any specific effect, but usually it makes sure that	767	systems or have any specific effect, but usually it makes sure that
553	directory changes get written to disc. It works for anything that	768	directory changes get written to disc. It works for anything that
554	can be opened for read-only, not just directories.	769	can be opened for read-only, not just directories.
555		770
		771	Future versions of this function might fall back to other methods
		772	when "fsync" on the directory fails (such as calling "sync").
		773
556	Passes 0 when everything went ok, and -1 on error.	774	Passes 0 when everything went ok, and -1 on error.
		775
		776	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		777	$callback->($status)
		778	This is a rather advanced IO::AIO call, which only works on
		779	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		780	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		781	note that the scalar must only be modified in-place while an aio
		782	operation is pending on it).
		783
		784	It calls the "msync" function of your OS, if available, with the
		785	memory area starting at $offset in the string and ending $length
		786	bytes later. If $length is negative, counts from the end, and if
		787	$length is "undef", then it goes till the end of the string. The
		788	flags can be a combination of "IO::AIO::MS_ASYNC",
		789	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		790
		791	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		792	$callback->($status)
		793	This is a rather advanced IO::AIO call, which works best on
		794	mmap(2)ed scalars.
		795
		796	It touches (reads or writes) all memory pages in the specified range
		797	inside the scalar. All caveats and parameters are the same as for
		798	"aio_msync", above, except for flags, which must be either 0 (which
		799	reads all pages and ensures they are instantiated) or
		800	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		801	and writing an octet from it, which dirties the page).
		802
		803	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		804	This is a rather advanced IO::AIO call, which works best on
		805	mmap(2)ed scalars.
		806
		807	It reads in all the pages of the underlying storage into memory (if
		808	any) and locks them, so they are not getting swapped/paged out or
		809	removed.
		810
		811	If $length is undefined, then the scalar will be locked till the
		812	end.
		813
		814	On systems that do not implement "mlock", this function returns -1
		815	and sets errno to "ENOSYS".
		816
		817	Note that the corresponding "munlock" is synchronous and is
		818	documented under "MISCELLANEOUS FUNCTIONS".
		819
		820	Example: open a file, mmap and mlock it - both will be undone when
		821	$data gets destroyed.
		822
		823	open my $fh, "<", $path or die "$path: $!";
		824	my $data;
		825	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		826	aio_mlock $data; # mlock in background
		827
		828	aio_mlockall $flags, $callback->($status)
		829	Calls the "mlockall" function with the given $flags (a combination
		830	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		831
		832	On systems that do not implement "mlockall", this function returns
		833	-1 and sets errno to "ENOSYS".
		834
		835	Note that the corresponding "munlockall" is synchronous and is
		836	documented under "MISCELLANEOUS FUNCTIONS".
		837
		838	Example: asynchronously lock all current and future pages into
		839	memory.
		840
		841	aio_mlockall IO::AIO::MCL_FUTURE;
557		842
558	aio_group $callback->(...)	843	aio_group $callback->(...)
559	This is a very special aio request: Instead of doing something, it	844	This is a very special aio request: Instead of doing something, it
560	is a container for other aio requests, which is useful if you want	845	is a container for other aio requests, which is useful if you want
561	to bundle many requests into a single, composite, request with a	846	to bundle many requests into a single, composite, request with a
…		…
604		889
605	cancel $req	890	cancel $req
606	Cancels the request, if possible. Has the effect of skipping	891	Cancels the request, if possible. Has the effect of skipping
607	execution when entering the execute state and skipping calling the	892	execution when entering the execute state and skipping calling the
608	callback when entering the the result state, but will leave the	893	callback when entering the the result state, but will leave the
609	request otherwise untouched. That means that requests that currently	894	request otherwise untouched (with the exception of readdir). That
610	execute will not be stopped and resources held by the request will	895	means that requests that currently execute will not be stopped and
611	not be freed prematurely.	896	resources held by the request will not be freed prematurely.
612		897
613	cb $req $callback->(...)	898	cb $req $callback->(...)
614	Replace (or simply set) the callback registered to the request.	899	Replace (or simply set) the callback registered to the request.
615		900
616	IO::AIO::GRP CLASS	901	IO::AIO::GRP CLASS
…		…
659	Their lifetime, simplified, looks like this: when they are empty, they	944	Their lifetime, simplified, looks like this: when they are empty, they
660	will finish very quickly. If they contain only requests that are in the	945	will finish very quickly. If they contain only requests that are in the
661	"done" state, they will also finish. Otherwise they will continue to	946	"done" state, they will also finish. Otherwise they will continue to
662	exist.	947	exist.
663		948
664	That means after creating a group you have some time to add requests.	949	That means after creating a group you have some time to add requests
665	And in the callbacks of those requests, you can add further requests to	950	(precisely before the callback has been invoked, which is only done
666	the group. And only when all those requests have finished will the the	951	within the "poll_cb"). And in the callbacks of those requests, you can
667	group itself finish.	952	add further requests to the group. And only when all those requests have
		953	finished will the the group itself finish.
668		954
669	add $grp ...	955	add $grp ...
670	$grp->add (...)	956	$grp->add (...)
671	Add one or more requests to the group. Any type of IO::AIO::REQ can	957	Add one or more requests to the group. Any type of IO::AIO::REQ can
672	be added, including other groups, as long as you do not create	958	be added, including other groups, as long as you do not create
…		…
676		962
677	$grp->cancel_subs	963	$grp->cancel_subs
678	Cancel all subrequests and clears any feeder, but not the group	964	Cancel all subrequests and clears any feeder, but not the group
679	request itself. Useful when you queued a lot of events but got a	965	request itself. Useful when you queued a lot of events but got a
680	result early.	966	result early.
		967
		968	The group request will finish normally (you cannot add requests to
		969	the group).
681		970
682	$grp->result (...)	971	$grp->result (...)
683	Set the result value(s) that will be passed to the group callback	972	Set the result value(s) that will be passed to the group callback
684	when all subrequests have finished and set the groups errno to the	973	when all subrequests have finished and set the groups errno to the
685	current value of errno (just like calling "errno" without an error	974	current value of errno (just like calling "errno" without an error
…		…
715	does not impose any limits).	1004	does not impose any limits).
716		1005
717	If the feed does not queue more requests when called, it will be	1006	If the feed does not queue more requests when called, it will be
718	automatically removed from the group.	1007	automatically removed from the group.
719		1008
720	If the feed limit is 0, it will be set to 2 automatically.	1009	If the feed limit is 0 when this method is called, it will be set to
		1010	2 automatically.
721		1011
722	Example:	1012	Example:
723		1013
724	# stat all files in @files, but only ever use four aio requests concurrently:	1014	# stat all files in @files, but only ever use four aio requests concurrently:
725		1015
…		…
736	Sets the feeder limit for the group: The feeder will be called	1026	Sets the feeder limit for the group: The feeder will be called
737	whenever the group contains less than this many requests.	1027	whenever the group contains less than this many requests.
738		1028
739	Setting the limit to 0 will pause the feeding process.	1029	Setting the limit to 0 will pause the feeding process.
740		1030
		1031	The default value for the limit is 0, but note that setting a feeder
		1032	automatically bumps it up to 2.
		1033
741	SUPPORT FUNCTIONS	1034	SUPPORT FUNCTIONS
742	EVENT PROCESSING AND EVENT LOOP INTEGRATION	1035	EVENT PROCESSING AND EVENT LOOP INTEGRATION
743	$fileno = IO::AIO::poll_fileno	1036	$fileno = IO::AIO::poll_fileno
744	Return the request result pipe file descriptor. This filehandle	1037	Return the request result pipe file descriptor. This filehandle
745	must be polled for reading by some mechanism outside this module	1038	must be polled for reading by some mechanism outside this module
746	(e.g. Event or select, see below or the SYNOPSIS). If the pipe	1039	(e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
747	becomes readable you have to call "poll_cb" to check the results.	1040	pipe becomes readable you have to call "poll_cb" to check the
		1041	results.
748		1042
749	See "poll_cb" for an example.	1043	See "poll_cb" for an example.
750		1044
751	IO::AIO::poll_cb	1045	IO::AIO::poll_cb
752	Process some outstanding events on the result pipe. You have to call	1046	Process some outstanding events on the result pipe. You have to call
753	this regularly. Returns the number of events processed. Returns	1047	this regularly. Returns 0 if all events could be processed (or there
754	immediately when no events are outstanding. The amount of events	1048	were no events to process), or -1 if it returned earlier for
755	processed depends on the settings of "IO::AIO::max_poll_req" and	1049	whatever reason. Returns immediately when no events are outstanding.
756	"IO::AIO::max_poll_time".	1050	The amount of events processed depends on the settings of
		1051	"IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".
757		1052
758	If not all requests were processed for whatever reason, the	1053	If not all requests were processed for whatever reason, the
759	filehandle will still be ready when "poll_cb" returns.	1054	filehandle will still be ready when "poll_cb" returns, so normally
		1055	you don't have to do anything special to have it called later.
		1056
		1057	Apart from calling "IO::AIO::poll_cb" when the event filehandle
		1058	becomes ready, it can be beneficial to call this function from loops
		1059	which submit a lot of requests, to make sure the results get
		1060	processed when they become available and not just when the loop is
		1061	finished and the event loop takes over again. This function returns
		1062	very fast when there are no outstanding requests.
760		1063
761	Example: Install an Event watcher that automatically calls	1064	Example: Install an Event watcher that automatically calls
762	IO::AIO::poll_cb with high priority:	1065	IO::AIO::poll_cb with high priority (more examples can be found in
		1066	the SYNOPSIS section, at the top of this document):
763		1067
764	Event->io (fd => IO::AIO::poll_fileno,	1068	Event->io (fd => IO::AIO::poll_fileno,
765	poll => 'r', async => 1,	1069	poll => 'r', async => 1,
766	cb => \&IO::AIO::poll_cb);	1070	cb => \&IO::AIO::poll_cb);
		1071
		1072	IO::AIO::poll_wait
		1073	If there are any outstanding requests and none of them in the result
		1074	phase, wait till the result filehandle becomes ready for reading
		1075	(simply does a "select" on the filehandle. This is useful if you
		1076	want to synchronously wait for some requests to finish).
		1077
		1078	See "nreqs" for an example.
		1079
		1080	IO::AIO::poll
		1081	Waits until some requests have been handled.
		1082
		1083	Returns the number of requests processed, but is otherwise strictly
		1084	equivalent to:
		1085
		1086	IO::AIO::poll_wait, IO::AIO::poll_cb
		1087
		1088	IO::AIO::flush
		1089	Wait till all outstanding AIO requests have been handled.
		1090
		1091	Strictly equivalent to:
		1092
		1093	IO::AIO::poll_wait, IO::AIO::poll_cb
		1094	while IO::AIO::nreqs;
767		1095
768	IO::AIO::max_poll_reqs $nreqs	1096	IO::AIO::max_poll_reqs $nreqs
769	IO::AIO::max_poll_time $seconds	1097	IO::AIO::max_poll_time $seconds
770	These set the maximum number of requests (default 0, meaning	1098	These set the maximum number of requests (default 0, meaning
771	infinity) that are being processed by "IO::AIO::poll_cb" in one	1099	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
795	# use a low priority so other tasks have priority	1123	# use a low priority so other tasks have priority
796	Event->io (fd => IO::AIO::poll_fileno,	1124	Event->io (fd => IO::AIO::poll_fileno,
797	poll => 'r', nice => 1,	1125	poll => 'r', nice => 1,
798	cb => &IO::AIO::poll_cb);	1126	cb => &IO::AIO::poll_cb);
799		1127
800	IO::AIO::poll_wait
801	If there are any outstanding requests and none of them in the result
802	phase, wait till the result filehandle becomes ready for reading
803	(simply does a "select" on the filehandle. This is useful if you
804	want to synchronously wait for some requests to finish).
805
806	See "nreqs" for an example.
807
808	IO::AIO::poll
809	Waits until some requests have been handled.
810
811	Returns the number of requests processed, but is otherwise strictly
812	equivalent to:
813
814	IO::AIO::poll_wait, IO::AIO::poll_cb
815
816	IO::AIO::flush
817	Wait till all outstanding AIO requests have been handled.
818
819	Strictly equivalent to:
820
821	IO::AIO::poll_wait, IO::AIO::poll_cb
822	while IO::AIO::nreqs;
823
824	CONTROLLING THE NUMBER OF THREADS	1128	CONTROLLING THE NUMBER OF THREADS
825	IO::AIO::min_parallel $nthreads	1129	IO::AIO::min_parallel $nthreads
826	Set the minimum number of AIO threads to $nthreads. The current	1130	Set the minimum number of AIO threads to $nthreads. The current
827	default is 8, which means eight asynchronous operations can execute	1131	default is 8, which means eight asynchronous operations can execute
828	concurrently at any one time (the number of outstanding requests,	1132	concurrently at any one time (the number of outstanding requests,
…		…
857		1161
858	Under normal circumstances you don't need to call this function.	1162	Under normal circumstances you don't need to call this function.
859		1163
860	IO::AIO::max_idle $nthreads	1164	IO::AIO::max_idle $nthreads
861	Limit the number of threads (default: 4) that are allowed to idle	1165	Limit the number of threads (default: 4) that are allowed to idle
862	(i.e., threads that did not get a request to process within 10	1166	(i.e., threads that did not get a request to process within the idle
863	seconds). That means if a thread becomes idle while $nthreads other	1167	timeout (default: 10 seconds). That means if a thread becomes idle
864	threads are also idle, it will free its resources and exit.	1168	while $nthreads other threads are also idle, it will free its
		1169	resources and exit.
865		1170
866	This is useful when you allow a large number of threads (e.g. 100 or	1171	This is useful when you allow a large number of threads (e.g. 100 or
867	1000) to allow for extremely high load situations, but want to free	1172	1000) to allow for extremely high load situations, but want to free
868	resources under normal circumstances (1000 threads can easily	1173	resources under normal circumstances (1000 threads can easily
869	consume 30MB of RAM).	1174	consume 30MB of RAM).
870		1175
871	The default is probably ok in most situations, especially if thread	1176	The default is probably ok in most situations, especially if thread
872	creation is fast. If thread creation is very slow on your system you	1177	creation is fast. If thread creation is very slow on your system you
873	might want to use larger values.	1178	might want to use larger values.
874		1179
		1180	IO::AIO::idle_timeout $seconds
		1181	Sets the minimum idle timeout (default 10) after which worker
		1182	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1183
875	$oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1184	IO::AIO::max_outstanding $maxreqs
		1185	Sets the maximum number of outstanding requests to $nreqs. If you do
		1186	queue up more than this number of requests, the next call to
		1187	"IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
		1188	"IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
		1189	no longer exceeded.
		1190
		1191	In other words, this setting does not enforce a queue limit, but can
		1192	be used to make poll functions block if the limit is exceeded.
		1193
876	This is a very bad function to use in interactive programs because	1194	This is a very bad function to use in interactive programs because
877	it blocks, and a bad way to reduce concurrency because it is	1195	it blocks, and a bad way to reduce concurrency because it is
878	inexact: Better use an "aio_group" together with a feed callback.	1196	inexact: Better use an "aio_group" together with a feed callback.
879		1197
880	Sets the maximum number of outstanding requests to $nreqs. If you do	1198	It's main use is in scripts without an event loop - when you want to
881	queue up more than this number of requests, the next call to the	1199	stat a lot of files, you can write somehting like this:
882	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
883	function will block until the limit is no longer exceeded.
884		1200
885	The default value is very large, so there is no practical limit on	1201	IO::AIO::max_outstanding 32;
		1202
		1203	for my $path (...) {
		1204	aio_stat $path , ...;
		1205	IO::AIO::poll_cb;
		1206	}
		1207
		1208	IO::AIO::flush;
		1209
		1210	The call to "poll_cb" inside the loop will normally return
		1211	instantly, but as soon as more thna 32 reqeusts are in-flight, it
		1212	will block until some requests have been handled. This keeps the
		1213	loop from pushing a large number of "aio_stat" requests onto the
		1214	queue.
		1215
		1216	The default value for "max_outstanding" is very large, so there is
886	the number of outstanding requests.	1217	no practical limit on the number of outstanding requests.
887
888	You can still queue as many requests as you want. Therefore,
889	"max_oustsanding" is mainly useful in simple scripts (with low
890	values) or as a stop gap to shield against fatal memory overflow
891	(with large values).
892		1218
893	STATISTICAL INFORMATION	1219	STATISTICAL INFORMATION
894	IO::AIO::nreqs	1220	IO::AIO::nreqs
895	Returns the number of requests currently in the ready, execute or	1221	Returns the number of requests currently in the ready, execute or
896	pending states (i.e. for which their callback has not been invoked	1222	pending states (i.e. for which their callback has not been invoked
…		…
907		1233
908	IO::AIO::npending	1234	IO::AIO::npending
909	Returns the number of requests currently in the pending state	1235	Returns the number of requests currently in the pending state
910	(executed, but not yet processed by poll_cb).	1236	(executed, but not yet processed by poll_cb).
911		1237
		1238	MISCELLANEOUS FUNCTIONS
		1239	IO::AIO implements some functions that might be useful, but are not
		1240	asynchronous.
		1241
		1242	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1243	Calls the "eio_sendfile_sync" function, which is like
		1244	"aio_sendfile", but is blocking (this makes most sense if you know
		1245	the input data is likely cached already and the output filehandle is
		1246	set to non-blocking operations).
		1247
		1248	Returns the number of bytes copied, or -1 on error.
		1249
		1250	IO::AIO::fadvise $fh, $offset, $len, $advice
		1251	Simply calls the "posix_fadvise" function (see its manpage for
		1252	details). The following advice constants are avaiable:
		1253	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1254	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1255	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1256
		1257	On systems that do not implement "posix_fadvise", this function
		1258	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1259
		1260	IO::AIO::madvise $scalar, $offset, $len, $advice
		1261	Simply calls the "posix_madvise" function (see its manpage for
		1262	details). The following advice constants are avaiable:
		1263	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1264	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1265	"IO::AIO::MADV_DONTNEED".
		1266
		1267	On systems that do not implement "posix_madvise", this function
		1268	returns ENOSYS, otherwise the return value of "posix_madvise".
		1269
		1270	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1271	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1272	$scalar (see its manpage for details). The following protect
		1273	constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1274	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1275
		1276	On systems that do not implement "mprotect", this function returns
		1277	ENOSYS, otherwise the return value of "mprotect".
		1278
		1279	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1280	Memory-maps a file (or anonymous memory range) and attaches it to
		1281	the given $scalar, which will act like a string scalar.
		1282
		1283	The only operations allowed on the scalar are "substr"/"vec" that
		1284	don't change the string length, and most read-only operations such
		1285	as copying it or searching it with regexes and so on.
		1286
		1287	Anything else is unsafe and will, at best, result in memory leaks.
		1288
		1289	The memory map associated with the $scalar is automatically removed
		1290	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1291	"IO::AIO::munmap" functions are called.
		1292
		1293	This calls the "mmap"(2) function internally. See your system's
		1294	manual page for details on the $length, $prot and $flags parameters.
		1295
		1296	The $length must be larger than zero and smaller than the actual
		1297	filesize.
		1298
		1299	$prot is a combination of "IO::AIO::PROT_NONE",
		1300	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1301	"IO::AIO::PROT_WRITE",
		1302
		1303	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1304	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1305	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1306	(which is set to "MAP_ANON" if your system only provides this
		1307	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1308	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1309	"IO::AIO::MAP_NONBLOCK"
		1310
		1311	If $fh is "undef", then a file descriptor of -1 is passed.
		1312
		1313	$offset is the offset from the start of the file - it generally must
		1314	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1315
		1316	Example:
		1317
		1318	use Digest::MD5;
		1319	use IO::AIO;
		1320
		1321	open my $fh, "<verybigfile"
		1322	or die "$!";
		1323
		1324	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1325	or die "verybigfile: $!";
		1326
		1327	my $fast_md5 = md5 $data;
		1328
		1329	IO::AIO::munmap $scalar
		1330	Removes a previous mmap and undefines the $scalar.
		1331
		1332	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1333	Calls the "munlock" function, undoing the effects of a previous
		1334	"aio_mlock" call (see its description for details).
		1335
		1336	IO::AIO::munlockall
		1337	Calls the "munlockall" function.
		1338
		1339	On systems that do not implement "munlockall", this function returns
		1340	ENOSYS, otherwise the return value of "munlockall".
		1341
		1342	EVENT LOOP INTEGRATION
		1343	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1344	automatically into many event loops:
		1345
		1346	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1347	use AnyEvent::AIO;
		1348
		1349	You can also integrate IO::AIO manually into many event loops, here are
		1350	some examples of how to do this:
		1351
		1352	# EV integration
		1353	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1354
		1355	# Event integration
		1356	Event->io (fd => IO::AIO::poll_fileno,
		1357	poll => 'r',
		1358	cb => \&IO::AIO::poll_cb);
		1359
		1360	# Glib/Gtk2 integration
		1361	add_watch Glib::IO IO::AIO::poll_fileno,
		1362	in => sub { IO::AIO::poll_cb; 1 };
		1363
		1364	# Tk integration
		1365	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1366	readable => \&IO::AIO::poll_cb);
		1367
		1368	# Danga::Socket integration
		1369	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1370	\&IO::AIO::poll_cb);
		1371
912	FORK BEHAVIOUR	1372	FORK BEHAVIOUR
913	This module should do "the right thing" when the process using it forks:	1373	Usage of pthreads in a program changes the semantics of fork
		1374	considerably. Specifically, only async-safe functions can be called
		1375	after fork. Perl doesn't know about this, so in general, you cannot call
		1376	fork with defined behaviour in perl. IO::AIO uses pthreads, so this
		1377	applies, but many other extensions and (for inexplicable reasons) perl
		1378	itself often is linked against pthreads, so this limitation applies.
914		1379
915	Before the fork, IO::AIO enters a quiescent state where no requests can	1380	Some operating systems have extensions that allow safe use of fork, and
916	be added in other threads and no results will be processed. After the	1381	this module should do "the right thing" on those, and tries on others.
917	fork the parent simply leaves the quiescent state and continues	1382	At the time of this writing (2011) only GNU/Linux supports these
918	request/result processing, while the child frees the request/result	1383	extensions to POSIX.
919	queue (so that the requests started before the fork will only be handled
920	in the parent). Threads will be started on demand until the limit set in
921	the parent process has been reached again.
922
923	In short: the parent will, after a short pause, continue as if fork had
924	not been called, while the child will act as if IO::AIO has not been
925	used yet.
926		1384
927	MEMORY USAGE	1385	MEMORY USAGE
928	Per-request usage:	1386	Per-request usage:
929		1387
930	Each aio request uses - depending on your architecture - around 100-200	1388	Each aio request uses - depending on your architecture - around 100-200
…		…
944		1402
945	KNOWN BUGS	1403	KNOWN BUGS
946	Known bugs will be fixed in the next release.	1404	Known bugs will be fixed in the next release.
947		1405
948	SEE ALSO	1406	SEE ALSO
949	Coro::AIO.	1407	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
		1408	more natural syntax.
950		1409
951	AUTHOR	1410	AUTHOR
952	Marc Lehmann <schmorp@schmorp.de>	1411	Marc Lehmann <schmorp@schmorp.de>
953	http://home.schmorp.de/	1412	http://home.schmorp.de/
954		1413

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Comparing IO-AIO/README (file contents): Revision 1.29 by root, Wed Apr 16 16:45:30 2008 UTC vs. Revision 1.48 by root, Wed Jun 29 11:25:17 2011 UTC

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Comparing IO-AIO/README (file contents):
Revision 1.29 by root, Wed Apr 16 16:45:30 2008 UTC vs.
Revision 1.48 by root, Wed Jun 29 11:25:17 2011 UTC