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

Comparing IO-AIO/README (file contents):
Revision 1.39 by root, Wed Aug 5 11:53:16 2009 UTC vs.
Revision 1.50 by root, Sun Oct 9 08:24:49 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
…		…
23	my $req = aio_unlink "/tmp/file", sub { };	23	my $req = aio_unlink "/tmp/file", sub { };
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
29	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30	use AnyEvent::AIO;
31
32	# EV integration
33	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
34
35	# Event integration
36	Event->io (fd => IO::AIO::poll_fileno,
37	poll => 'r',
38	cb => \&IO::AIO::poll_cb);
39
40	# Glib/Gtk2 integration
41	add_watch Glib::IO IO::AIO::poll_fileno,
42	in => sub { IO::AIO::poll_cb; 1 };
43
44	# Tk integration
45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46	readable => \&IO::AIO::poll_cb);
47
48	# Danga::Socket integration
49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50	\&IO::AIO::poll_cb);
51		28
52	DESCRIPTION	29	DESCRIPTION
53	This module implements asynchronous I/O using whatever means your	30	This module implements asynchronous I/O using whatever means your
54	operating system supports. It is implemented as an interface to "libeio"	31	operating system supports. It is implemented as an interface to "libeio"
55	(<http://software.schmorp.de/pkg/libeio.html>).	32	(<http://software.schmorp.de/pkg/libeio.html>).
…		…
95		72
96	# register the IO::AIO callback with EV	73	# register the IO::AIO callback with EV
97	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&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;
…		…
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_wd $pathname, $callback->($wd)
		156	aio_open $pathname, $flags, $mode, $callback->($fh)
		157	aio_close $fh, $callback->($status)
		158	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		159	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		160	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		161	aio_readahead $fh,$offset,$length, $callback->($retval)
		162	aio_stat $fh_or_path, $callback->($status)
		163	aio_lstat $fh, $callback->($status)
		164	aio_statvfs $fh_or_path, $callback->($statvfs)
		165	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		166	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		167	aio_truncate $fh_or_path, $offset, $callback->($status)
		168	aio_chmod $fh_or_path, $mode, $callback->($status)
		169	aio_unlink $pathname, $callback->($status)
		170	aio_mknod $pathname, $mode, $dev, $callback->($status)
		171	aio_link $srcpath, $dstpath, $callback->($status)
		172	aio_symlink $srcpath, $dstpath, $callback->($status)
		173	aio_readlink $pathname, $callback->($link)
		174	aio_realpath $pathname, $callback->($link)
		175	aio_rename $srcpath, $dstpath, $callback->($status)
		176	aio_mkdir $pathname, $mode, $callback->($status)
		177	aio_rmdir $pathname, $callback->($status)
		178	aio_readdir $pathname, $callback->($entries)
		179	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		180	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		181	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		182	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		183	aio_load $pathname, $data, $callback->($status)
		184	aio_copy $srcpath, $dstpath, $callback->($status)
		185	aio_move $srcpath, $dstpath, $callback->($status)
		186	aio_rmtree $pathname, $callback->($status)
		187	aio_sync $callback->($status)
		188	aio_syncfs $fh, $callback->($status)
		189	aio_fsync $fh, $callback->($status)
		190	aio_fdatasync $fh, $callback->($status)
		191	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		192	aio_pathsync $pathname, $callback->($status)
		193	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		194	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		195	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		196	aio_mlockall $flags, $callback->($status)
		197	aio_group $callback->(...)
		198	aio_nop $callback->()
		199
		200	$prev_pri = aioreq_pri [$pri]
		201	aioreq_nice $pri_adjust
		202
		203	IO::AIO::poll_wait
		204	IO::AIO::poll_cb
		205	IO::AIO::poll
		206	IO::AIO::flush
		207	IO::AIO::max_poll_reqs $nreqs
		208	IO::AIO::max_poll_time $seconds
		209	IO::AIO::min_parallel $nthreads
		210	IO::AIO::max_parallel $nthreads
		211	IO::AIO::max_idle $nthreads
		212	IO::AIO::idle_timeout $seconds
		213	IO::AIO::max_outstanding $maxreqs
		214	IO::AIO::nreqs
		215	IO::AIO::nready
		216	IO::AIO::npending
		217
		218	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		219	IO::AIO::fadvise $fh, $offset, $len, $advice
		220	IO::AIO::madvise $scalar, $offset, $length, $advice
		221	IO::AIO::mprotect $scalar, $offset, $length, $protect
		222	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		223	IO::AIO::munlockall
		224
173	AIO REQUEST FUNCTIONS	225	AIO REQUEST FUNCTIONS
174	All the "aio_*" calls are more or less thin wrappers around the syscall	226	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	227	with the same name (sans "aio_"). The arguments are similar or
176	identical, and they all accept an additional (and optional) $callback	228	identical, and they all accept an additional (and optional) $callback
177	argument which must be a code reference. This code reference will get	229	argument which must be a code reference. This code reference will be
178	called with the syscall return code (e.g. most syscalls return -1 on
179	error, unlike perl, which usually delivers "false") as its sole argument
180	after the given syscall has been executed asynchronously.	230	called after the syscall has been executed in an asynchronous fashion.
		231	The results of the request will be passed as arguments to the callback
		232	(and, if an error occured, in $!) - for most requests the syscall return
		233	code (e.g. most syscalls return -1 on error, unlike perl, which usually
		234	delivers "false").
		235
		236	Some requests (such as "aio_readdir") pass the actual results and
		237	communicate failures by passing "undef".
181		238
182	All functions expecting a filehandle keep a copy of the filehandle	239	All functions expecting a filehandle keep a copy of the filehandle
183	internally until the request has finished.	240	internally until the request has finished.
184		241
185	All functions return request objects of type IO::AIO::REQ that allow	242	All functions return request objects of type IO::AIO::REQ that allow
186	further manipulation of those requests while they are in-flight.	243	further manipulation of those requests while they are in-flight.
187		244
188	The pathnames you pass to these routines must be absolute and encoded	245	The pathnames you pass to these routines should be absolute. The
189	as octets. The reason for the former is that at the time the request is	246	reason for this is that at the time the request is being executed, the
190	being executed, the current working directory could have changed.	247	current working directory could have changed. Alternatively, you can
191	Alternatively, you can make sure that you never change the current	248	make sure that you never change the current working directory anywhere
192	working directory anywhere in the program and then use relative paths.	249	in the program and then use relative paths. You can also take advantage
		250	of IO::AIOs working directory abstraction, that lets you specify paths
		251	relative to some previously-opened "working directory object" - see the
		252	description of the "IO::AIO::WD" class later in this document.
193		253
194	To encode pathnames as octets, either make sure you either: a) always	254	To encode pathnames as octets, either make sure you either: a) always
195	pass in filenames you got from outside (command line, readdir etc.)	255	pass in filenames you got from outside (command line, readdir etc.)
196	without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module	256	without tinkering, b) are in your native filesystem encoding, c) use the
197	and encode your pathnames to the locale (or other) encoding in effect in	257	Encode module and encode your pathnames to the locale (or other)
198	the user environment, d) use Glib::filename_from_unicode on unicode	258	encoding in effect in the user environment, d) use
199	filenames or e) use something else to ensure your scalar has the correct	259	Glib::filename_from_unicode on unicode filenames or e) use something
200	contents.	260	else to ensure your scalar has the correct contents.
201		261
202	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	262	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
203	handles correctly whether it is set or not.	263	handles correctly whether it is set or not.
204		264
205	$prev_pri = aioreq_pri [$pri]	265	$prev_pri = aioreq_pri [$pri]
…		…
248	will be modified by the umask in effect then the request is being	308	will be modified by the umask in effect then the request is being
249	executed, so better never change the umask.	309	executed, so better never change the umask.
250		310
251	Example:	311	Example:
252		312
253	aio_open "/etc/passwd", O_RDONLY, 0, sub {	313	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
254	if ($_[0]) {	314	if ($_[0]) {
255	print "open successful, fh is $_[0]\n";	315	print "open successful, fh is $_[0]\n";
256	...	316	...
257	} else {	317	} else {
258	die "open failed: $!\n";	318	die "open failed: $!\n";
259	}	319	}
260	};	320	};
261		321
		322	In addition to all the common open modes/flags ("O_RDONLY",
		323	"O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
		324	"O_APPEND"), the following POSIX and non-POSIX constants are
		325	available (missing ones on your system are, as usual, 0):
		326
		327	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
		328	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
		329	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
		330
262	aio_close $fh, $callback->($status)	331	aio_close $fh, $callback->($status)
263	Asynchronously close a file and call the callback with the result	332	Asynchronously close a file and call the callback with the result
264	code.	333	code.
265		334
266	Unfortunately, you can't do this to perl. Perl insists very	335	Unfortunately, you can't do this to perl. Perl insists very
…		…
309	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	378	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
310	Tries to copy $length bytes from $in_fh to $out_fh. It starts	379	Tries to copy $length bytes from $in_fh to $out_fh. It starts
311	reading at byte offset $in_offset, and starts writing at the current	380	reading at byte offset $in_offset, and starts writing at the current
312	file offset of $out_fh. Because of that, it is not safe to issue	381	file offset of $out_fh. Because of that, it is not safe to issue
313	more than one "aio_sendfile" per $out_fh, as they will interfere	382	more than one "aio_sendfile" per $out_fh, as they will interfere
314	with each other.	383	with each other. The same $in_fh works fine though, as this function
		384	does not move or use the file offset of $in_fh.
315		385
		386	Please note that "aio_sendfile" can read more bytes from $in_fh than
		387	are written, and there is no way to find out how many more bytes
		388	have been read from "aio_sendfile" alone, as "aio_sendfile" only
		389	provides the number of bytes written to $out_fh. Only if the result
		390	value equals $length one can assume that $length bytes have been
		391	read.
		392
		393	Unlike with other "aio_" functions, it makes a lot of sense to use
		394	"aio_sendfile" on non-blocking sockets, as long as one end
		395	(typically the $in_fh) is a file - the file I/O will then be
		396	asynchronous, while the socket I/O will be non-blocking. Note,
		397	however, that you can run into a trap where "aio_sendfile" reads
		398	some data with readahead, then fails to write all data, and when the
		399	socket is ready the next time, the data in the cache is already
		400	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		401	"aio_read" + "aio_write" let's you better control resource usage.
		402
316	This call tries to make use of a native "sendfile" syscall to	403	This call tries to make use of a native "sendfile"-like syscall to
317	provide zero-copy operation. For this to work, $out_fh should refer	404	provide zero-copy operation. For this to work, $out_fh should refer
318	to a socket, and $in_fh should refer to mmap'able file.	405	to a socket, and $in_fh should refer to an mmap'able file.
319		406
320	If the native sendfile call fails or is not implemented, it will be	407	If a native sendfile cannot be found or it fails with "ENOSYS",
321	emulated, so you can call "aio_sendfile" on any type of filehandle	408	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
322	regardless of the limitations of the operating system.	409	"ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
		410	any type of filehandle regardless of the limitations of the
		411	operating system.
323		412
324	Please note, however, that "aio_sendfile" can read more bytes from	413	As native sendfile syscalls (as practically any non-POSIX interface
325	$in_fh than are written, and there is no way to find out how many	414	hacked together in a hurry to improve benchmark numbers) tend to be
326	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	415	rather buggy on many systems, this implementation tries to work
327	only provides the number of bytes written to $out_fh. Only if the	416	around some known bugs in Linux and FreeBSD kernels (probably
328	result value equals $length one can assume that $length bytes have	417	others, too), but that might fail, so you really really should check
329	been read.	418	the return value of "aio_sendfile" - fewre bytes than expected might
		419	have been transferred.
330		420
331	aio_readahead $fh,$offset,$length, $callback->($retval)	421	aio_readahead $fh,$offset,$length, $callback->($retval)
332	"aio_readahead" populates the page cache with data from a file so	422	"aio_readahead" populates the page cache with data from a file so
333	that subsequent reads from that file will not block on disk I/O. The	423	that subsequent reads from that file will not block on disk I/O. The
334	$offset argument specifies the starting point from which data is to	424	$offset argument specifies the starting point from which data is to
…		…
355	Currently, the stats are always 64-bit-stats, i.e. instead of	445	Currently, the stats are always 64-bit-stats, i.e. instead of
356	returning an error when stat'ing a large file, the results will be	446	returning an error when stat'ing a large file, the results will be
357	silently truncated unless perl itself is compiled with large file	447	silently truncated unless perl itself is compiled with large file
358	support.	448	support.
359		449
		450	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		451	the following constants and functions (if not implemented, the
		452	constants will be 0 and the functions will either "croak" or fall
		453	back on traditional behaviour).
		454
		455	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		456	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		457	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		458
360	Example: Print the length of /etc/passwd:	459	Example: Print the length of /etc/passwd:
361		460
362	aio_stat "/etc/passwd", sub {	461	aio_stat "/etc/passwd", sub {
363	$_[0] and die "stat failed: $!";	462	$_[0] and die "stat failed: $!";
364	print "size is ", -s _, "\n";	463	print "size is ", -s _, "\n";
365	};	464	};
366		465
		466	aio_statvfs $fh_or_path, $callback->($statvfs)
		467	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		468	whether a file handle or path was passed.
		469
		470	On success, the callback is passed a hash reference with the
		471	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		472	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		473	failure, "undef" is passed.
		474
		475	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		476	and "ST_NOSUID".
		477
		478	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		479	their correct value when available, or to 0 on systems that do not
		480	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		481	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		482	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		483
		484	Example: stat "/wd" and dump out the data if successful.
		485
		486	aio_statvfs "/wd", sub {
		487	my $f = $_[0]
		488	or die "statvfs: $!";
		489
		490	use Data::Dumper;
		491	say Dumper $f;
		492	};
		493
		494	# result:
		495	{
		496	bsize => 1024,
		497	bfree => 4333064312,
		498	blocks => 10253828096,
		499	files => 2050765568,
		500	flag => 4096,
		501	favail => 2042092649,
		502	bavail => 4333064312,
		503	ffree => 2042092649,
		504	namemax => 255,
		505	frsize => 1024,
		506	fsid => 1810
		507	}
		508
367	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	509	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
368	Works like perl's "utime" function (including the special case of	510	Works like perl's "utime" function (including the special case of
369	$atime and $mtime being undef). Fractional times are supported if	511	$atime and $mtime being undef). Fractional times are supported if
370	the underlying syscalls support them.	512	the underlying syscalls support them.
371		513
…		…
400		542
401	aio_unlink $pathname, $callback->($status)	543	aio_unlink $pathname, $callback->($status)
402	Asynchronously unlink (delete) a file and call the callback with the	544	Asynchronously unlink (delete) a file and call the callback with the
403	result code.	545	result code.
404		546
405	aio_mknod $path, $mode, $dev, $callback->($status)	547	aio_mknod $pathname, $mode, $dev, $callback->($status)
406	[EXPERIMENTAL]	548	[EXPERIMENTAL]
407		549
408	Asynchronously create a device node (or fifo). See mknod(2).	550	Asynchronously create a device node (or fifo). See mknod(2).
409		551
410	The only (POSIX-) portable way of calling this function is:	552	The only (POSIX-) portable way of calling this function is:
411		553
412	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	554	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		555
		556	See "aio_stat" for info about some potentially helpful extra
		557	constants and functions.
413		558
414	aio_link $srcpath, $dstpath, $callback->($status)	559	aio_link $srcpath, $dstpath, $callback->($status)
415	Asynchronously create a new link to the existing object at $srcpath	560	Asynchronously create a new link to the existing object at $srcpath
416	at the path $dstpath and call the callback with the result code.	561	at the path $dstpath and call the callback with the result code.
417		562
418	aio_symlink $srcpath, $dstpath, $callback->($status)	563	aio_symlink $srcpath, $dstpath, $callback->($status)
419	Asynchronously create a new symbolic link to the existing object at	564	Asynchronously create a new symbolic link to the existing object at
420	$srcpath at the path $dstpath and call the callback with the result	565	$srcpath at the path $dstpath and call the callback with the result
421	code.	566	code.
422		567
423	aio_readlink $path, $callback->($link)	568	aio_readlink $pathname, $callback->($link)
424	Asynchronously read the symlink specified by $path and pass it to	569	Asynchronously read the symlink specified by $path and pass it to
425	the callback. If an error occurs, nothing or undef gets passed to	570	the callback. If an error occurs, nothing or undef gets passed to
426	the callback.	571	the callback.
		572
		573	aio_realpath $pathname, $callback->($path)
		574	Asynchronously make the path absolute and resolve any symlinks in
		575	$path. The resulting path only consists of directories (Same as
		576	Cwd::realpath).
		577
		578	This request can be used to get the absolute path of the current
		579	working directory by passing it a path of . (a single dot).
427		580
428	aio_rename $srcpath, $dstpath, $callback->($status)	581	aio_rename $srcpath, $dstpath, $callback->($status)
429	Asynchronously rename the object at $srcpath to $dstpath, just as	582	Asynchronously rename the object at $srcpath to $dstpath, just as
430	rename(2) and call the callback with the result code.	583	rename(2) and call the callback with the result code.
431		584
…		…
445		598
446	The callback is passed a single argument which is either "undef" or	599	The callback is passed a single argument which is either "undef" or
447	an array-ref with the filenames.	600	an array-ref with the filenames.
448		601
449	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	602	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
450	Quite similar to "aio_readdir", but the $flags argument allows to	603	Quite similar to "aio_readdir", but the $flags argument allows one
451	tune behaviour and output format. In case of an error, $entries will	604	to tune behaviour and output format. In case of an error, $entries
452	be "undef".	605	will be "undef".
453		606
454	The flags are a combination of the following constants, ORed	607	The flags are a combination of the following constants, ORed
455	together (the flags will also be passed to the callback, possibly	608	together (the flags will also be passed to the callback, possibly
456	modified):	609	modified):
457		610
458	IO::AIO::READDIR_DENTS	611	IO::AIO::READDIR_DENTS
459	When this flag is off, then the callback gets an arrayref with	612	When this flag is off, then the callback gets an arrayref
460	of names only (as with "aio_readdir"), otherwise it gets an	613	consisting of names only (as with "aio_readdir"), otherwise it
461	arrayref with "[$name, $type, $inode]" arrayrefs, each	614	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
462	describing a single directory entry in more detail.	615	describing a single directory entry in more detail.
463		616
464	$name is the name of the entry.	617	$name is the name of the entry.
465		618
466	$type is one of the "IO::AIO::DT_xxx" constants:	619	$type is one of the "IO::AIO::DT_xxx" constants:
…		…
479	unspecified content on systems that do not deliver the inode	632	unspecified content on systems that do not deliver the inode
480	information.	633	information.
481		634
482	IO::AIO::READDIR_DIRS_FIRST	635	IO::AIO::READDIR_DIRS_FIRST
483	When this flag is set, then the names will be returned in an	636	When this flag is set, then the names will be returned in an
484	order where likely directories come first. This is useful when	637	order where likely directories come first, in optimal stat
485	you need to quickly find directories, or you want to find all	638	order. This is useful when you need to quickly find directories,
486	directories while avoiding to stat() each entry.	639	or you want to find all directories while avoiding to stat()
		640	each entry.
487		641
488	If the system returns type information in readdir, then this is	642	If the system returns type information in readdir, then this is
489	used to find directories directly. Otherwise, likely directories	643	used to find directories directly. Otherwise, likely directories
490	are files beginning with ".", or otherwise files with no dots,	644	are names beginning with ".", or otherwise names with no dots,
491	of which files with short names are tried first.	645	of which names with short names are tried first.
492		646
493	IO::AIO::READDIR_STAT_ORDER	647	IO::AIO::READDIR_STAT_ORDER
494	When this flag is set, then the names will be returned in an	648	When this flag is set, then the names will be returned in an
495	order suitable for stat()'ing each one. That is, when you plan	649	order suitable for stat()'ing each one. That is, when you plan
496	to stat() all files in the given directory, then the returned	650	to stat() all files in the given directory, then the returned
…		…
501	optimal stat order.	655	optimal stat order.
502		656
503	IO::AIO::READDIR_FOUND_UNKNOWN	657	IO::AIO::READDIR_FOUND_UNKNOWN
504	This flag should not be set when calling "aio_readdirx".	658	This flag should not be set when calling "aio_readdirx".
505	Instead, it is being set by "aio_readdirx", when any of the	659	Instead, it is being set by "aio_readdirx", when any of the
506	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this	660	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this
507	flag therefore indicates that all $type's are known, which can	661	flag therefore indicates that all $type's are known, which can
508	be used to speed up some algorithms.	662	be used to speed up some algorithms.
509		663
510	aio_load $path, $data, $callback->($status)	664	aio_load $pathname, $data, $callback->($status)
511	This is a composite request that tries to fully load the given file	665	This is a composite request that tries to fully load the given file
512	into memory. Status is the same as with aio_read.	666	into memory. Status is the same as with aio_read.
513		667
514	aio_copy $srcpath, $dstpath, $callback->($status)	668	aio_copy $srcpath, $dstpath, $callback->($status)
515	Try to copy the file (directories not supported as either source	669	Try to copy the file (directories not supported as either source
516	or destination) from $srcpath to $dstpath and call the callback with	670	or destination) from $srcpath to $dstpath and call the callback with
517	the 0 (error) or -1 ok.	671	a status of 0 (ok) or -1 (error, see $!).
518		672
519	This is a composite request that creates the destination file with	673	This is a composite request that creates the destination file with
520	mode 0200 and copies the contents of the source file into it using	674	mode 0200 and copies the contents of the source file into it using
521	"aio_sendfile", followed by restoring atime, mtime, access mode and	675	"aio_sendfile", followed by restoring atime, mtime, access mode and
522	uid/gid, in that order.	676	uid/gid, in that order.
…		…
526	uid/gid, where errors are being ignored.	680	uid/gid, where errors are being ignored.
527		681
528	aio_move $srcpath, $dstpath, $callback->($status)	682	aio_move $srcpath, $dstpath, $callback->($status)
529	Try to move the file (directories not supported as either source	683	Try to move the file (directories not supported as either source
530	or destination) from $srcpath to $dstpath and call the callback with	684	or destination) from $srcpath to $dstpath and call the callback with
531	the 0 (error) or -1 ok.	685	a status of 0 (ok) or -1 (error, see $!).
532		686
533	This is a composite request that tries to rename(2) the file first;	687	This is a composite request that tries to rename(2) the file first;
534	if rename fails with "EXDEV", it copies the file with "aio_copy"	688	if rename fails with "EXDEV", it copies the file with "aio_copy"
535	and, if that is successful, unlinks the $srcpath.	689	and, if that is successful, unlinks the $srcpath.
536		690
537	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	691	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
538	Scans a directory (similar to "aio_readdir") but additionally tries	692	Scans a directory (similar to "aio_readdir") but additionally tries
539	to efficiently separate the entries of directory $path into two sets	693	to efficiently separate the entries of directory $path into two sets
540	of names, directories you can recurse into (directories), and ones	694	of names, directories you can recurse into (directories), and ones
541	you cannot recurse into (everything else, including symlinks to	695	you cannot recurse into (everything else, including symlinks to
542	directories).	696	directories).
…		…
575	Then entries will be sorted into likely directories a non-initial	729	Then entries will be sorted into likely directories a non-initial
576	dot currently) and likely non-directories (see "aio_readdirx"). Then	730	dot currently) and likely non-directories (see "aio_readdirx"). Then
577	every entry plus an appended "/." will be "stat"'ed, likely	731	every entry plus an appended "/." will be "stat"'ed, likely
578	directories first, in order of their inode numbers. If that	732	directories first, in order of their inode numbers. If that
579	succeeds, it assumes that the entry is a directory or a symlink to	733	succeeds, it assumes that the entry is a directory or a symlink to
580	directory (which will be checked seperately). This is often faster	734	directory (which will be checked separately). This is often faster
581	than stat'ing the entry itself because filesystems might detect the	735	than stat'ing the entry itself because filesystems might detect the
582	type of the entry without reading the inode data (e.g. ext2fs	736	type of the entry without reading the inode data (e.g. ext2fs
583	filetype feature), even on systems that cannot return the filetype	737	filetype feature), even on systems that cannot return the filetype
584	information on readdir.	738	information on readdir.
585		739
…		…
591		745
592	It will also likely work on non-POSIX filesystems with reduced	746	It will also likely work on non-POSIX filesystems with reduced
593	efficiency as those tend to return 0 or 1 as link counts, which	747	efficiency as those tend to return 0 or 1 as link counts, which
594	disables the directory counting heuristic.	748	disables the directory counting heuristic.
595		749
596	aio_rmtree $path, $callback->($status)	750	aio_rmtree $pathname, $callback->($status)
597	Delete a directory tree starting (and including) $path, return the	751	Delete a directory tree starting (and including) $path, return the
598	status of the final "rmdir" only. This is a composite request that	752	status of the final "rmdir" only. This is a composite request that
599	uses "aio_scandir" to recurse into and rmdir directories, and unlink	753	uses "aio_scandir" to recurse into and rmdir directories, and unlink
600	everything else.	754	everything else.
601		755
…		…
610	Asynchronously call fdatasync on the given filehandle and call the	764	Asynchronously call fdatasync on the given filehandle and call the
611	callback with the fdatasync result code.	765	callback with the fdatasync result code.
612		766
613	If this call isn't available because your OS lacks it or it couldn't	767	If this call isn't available because your OS lacks it or it couldn't
614	be detected, it will be emulated by calling "fsync" instead.	768	be detected, it will be emulated by calling "fsync" instead.
		769
		770	aio_syncfs $fh, $callback->($status)
		771	Asynchronously call the syncfs syscall to sync the filesystem
		772	associated to the given filehandle and call the callback with the
		773	syncfs result code. If syncfs is not available, calls sync(), but
		774	returns -1 and sets errno to "ENOSYS" nevertheless.
615		775
616	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	776	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
617	Sync the data portion of the file specified by $offset and $length	777	Sync the data portion of the file specified by $offset and $length
618	to disk (but NOT the metadata), by calling the Linux-specific	778	to disk (but NOT the metadata), by calling the Linux-specific
619	sync_file_range call. If sync_file_range is not available or it	779	sync_file_range call. If sync_file_range is not available or it
…		…
623	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",	783	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
624	"IO::AIO::SYNC_FILE_RANGE_WRITE" and	784	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
625	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range	785	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
626	manpage for details.	786	manpage for details.
627		787
628	aio_pathsync $path, $callback->($status)	788	aio_pathsync $pathname, $callback->($status)
629	This request tries to open, fsync and close the given path. This is	789	This request tries to open, fsync and close the given path. This is
630	a composite request intended to sync directories after directory	790	a composite request intended to sync directories after directory
631	operations (E.g. rename). This might not work on all operating	791	operations (E.g. rename). This might not work on all operating
632	systems or have any specific effect, but usually it makes sure that	792	systems or have any specific effect, but usually it makes sure that
633	directory changes get written to disc. It works for anything that	793	directory changes get written to disc. It works for anything that
…		…
636	Future versions of this function might fall back to other methods	796	Future versions of this function might fall back to other methods
637	when "fsync" on the directory fails (such as calling "sync").	797	when "fsync" on the directory fails (such as calling "sync").
638		798
639	Passes 0 when everything went ok, and -1 on error.	799	Passes 0 when everything went ok, and -1 on error.
640		800
		801	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		802	$callback->($status)
		803	This is a rather advanced IO::AIO call, which only works on
		804	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		805	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		806	note that the scalar must only be modified in-place while an aio
		807	operation is pending on it).
		808
		809	It calls the "msync" function of your OS, if available, with the
		810	memory area starting at $offset in the string and ending $length
		811	bytes later. If $length is negative, counts from the end, and if
		812	$length is "undef", then it goes till the end of the string. The
		813	flags can be a combination of "IO::AIO::MS_ASYNC",
		814	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		815
		816	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		817	$callback->($status)
		818	This is a rather advanced IO::AIO call, which works best on
		819	mmap(2)ed scalars.
		820
		821	It touches (reads or writes) all memory pages in the specified range
		822	inside the scalar. All caveats and parameters are the same as for
		823	"aio_msync", above, except for flags, which must be either 0 (which
		824	reads all pages and ensures they are instantiated) or
		825	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		826	and writing an octet from it, which dirties the page).
		827
		828	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		829	This is a rather advanced IO::AIO call, which works best on
		830	mmap(2)ed scalars.
		831
		832	It reads in all the pages of the underlying storage into memory (if
		833	any) and locks them, so they are not getting swapped/paged out or
		834	removed.
		835
		836	If $length is undefined, then the scalar will be locked till the
		837	end.
		838
		839	On systems that do not implement "mlock", this function returns -1
		840	and sets errno to "ENOSYS".
		841
		842	Note that the corresponding "munlock" is synchronous and is
		843	documented under "MISCELLANEOUS FUNCTIONS".
		844
		845	Example: open a file, mmap and mlock it - both will be undone when
		846	$data gets destroyed.
		847
		848	open my $fh, "<", $path or die "$path: $!";
		849	my $data;
		850	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		851	aio_mlock $data; # mlock in background
		852
		853	aio_mlockall $flags, $callback->($status)
		854	Calls the "mlockall" function with the given $flags (a combination
		855	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		856
		857	On systems that do not implement "mlockall", this function returns
		858	-1 and sets errno to "ENOSYS".
		859
		860	Note that the corresponding "munlockall" is synchronous and is
		861	documented under "MISCELLANEOUS FUNCTIONS".
		862
		863	Example: asynchronously lock all current and future pages into
		864	memory.
		865
		866	aio_mlockall IO::AIO::MCL_FUTURE;
		867
641	aio_group $callback->(...)	868	aio_group $callback->(...)
642	This is a very special aio request: Instead of doing something, it	869	This is a very special aio request: Instead of doing something, it
643	is a container for other aio requests, which is useful if you want	870	is a container for other aio requests, which is useful if you want
644	to bundle many requests into a single, composite, request with a	871	to bundle many requests into a single, composite, request with a
645	definite callback and the ability to cancel the whole request with	872	definite callback and the ability to cancel the whole request with
…		…
678	While it is theoretically handy to have simple I/O scheduling	905	While it is theoretically handy to have simple I/O scheduling
679	requests like sleep and file handle readable/writable, the overhead	906	requests like sleep and file handle readable/writable, the overhead
680	this creates is immense (it blocks a thread for a long time) so do	907	this creates is immense (it blocks a thread for a long time) so do
681	not use this function except to put your application under	908	not use this function except to put your application under
682	artificial I/O pressure.	909	artificial I/O pressure.
		910
		911	IO::AIO::WD - multiple working directories
		912	Your process only has one current working directory, which is used by
		913	all threads. This makes it hard to use relative paths (some other
		914	component could call "chdir" at any time, and it is hard to control when
		915	the path will be used by IO::AIO).
		916
		917	One solution for this is to always use absolute paths. This usually
		918	works, but can be quite slow (the kernel has to walk the whole path on
		919	every access), and can also be a hassle to implement.
		920
		921	Newer POSIX systems have a number of functions (openat, fdopendir,
		922	futimensat and so on) that make it possible to specify working
		923	directories per operation.
		924
		925	For portability, and because the clowns who "designed", or shall I
		926	write, perpetrated this new interface were obviously half-drunk, this
		927	abstraction cannot be perfect, though.
		928
		929	IO::AIO allows you to convert directory paths into a so-called
		930	IO::AIO::WD object. This object stores the canonicalised, absolute
		931	version of the path, and on systems that allow it, also a directory file
		932	descriptor.
		933
		934	Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
		935	or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
		936	object and a pathname instead (or the IO::AIO::WD object alone, which
		937	gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
		938	IO::AIO::WD object is ignored, otherwise the pathname is resolved
		939	relative to that IO::AIO::WD object.
		940
		941	For example, to get a wd object for /etc and then stat passwd inside,
		942	you would write:
		943
		944	aio_wd "/etc", sub {
		945	my $etcdir = shift;
		946
		947	# although $etcdir can be undef on error, there is generally no reason
		948	# to check for errors here, as aio_stat will fail with ENOENT
		949	# when $etcdir is undef.
		950
		951	aio_stat [$etcdir, "passwd"], sub {
		952	# yay
		953	};
		954	};
		955
		956	That "aio_wd" is a request and not a normal function shows that creating
		957	an IO::AIO::WD object is itself a potentially blocking operation, which
		958	is why it is done asynchronously.
		959
		960	To stat the directory obtained with "aio_wd" above, one could write
		961	either of the following three request calls:
		962
		963	aio_lstat "/etc" , sub { ... # pathname as normal string
		964	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		965	aio_lstat $wd , sub { ... # shorthand for the previous
		966
		967	As with normal pathnames, IO::AIO keeps a copy of the working directory
		968	object and the pathname string, so you could write the following without
		969	causing any issues due to $path getting reused:
		970
		971	my $path = [$wd, undef];
		972
		973	for my $name (qw(abc def ghi)) {
		974	$path->[1] = $name;
		975	aio_stat $path, sub {
		976	# ...
		977	};
		978	}
		979
		980	There are some caveats: when directories get renamed (or deleted), the
		981	pathname string doesn't change, so will point to the new directory (or
		982	nowhere at all), while the directory fd, if available on the system,
		983	will still point to the original directory. Most functions accepting a
		984	pathname will use the directory fd on newer systems, and the string on
		985	older systems. Some functions (such as realpath) will always rely on the
		986	string form of the pathname.
		987
		988	So this fucntionality is mainly useful to get some protection against
		989	"chdir", to easily get an absolute path out of a relative path for
		990	future reference, and to speed up doing many operations in the same
		991	directory (e.g. when stat'ing all files in a directory).
		992
		993	The following functions implement this working directory abstraction:
		994
		995	aio_wd $pathname, $callback->($wd)
		996	Asynchonously canonicalise the given pathname and convert it to an
		997	IO::AIO::WD object representing it. If possible and supported on the
		998	system, also open a directory fd to speed up pathname resolution
		999	relative to this working directory.
		1000
		1001	If something goes wrong, then "undef" is passwd to the callback
		1002	instead of a working directory object and $! is set appropriately.
		1003	Since passing "undef" as working directory component of a pathname
		1004	fails the request with "ENOENT", there is often no need for error
		1005	checking in the "aio_wd" callback, as future requests using the
		1006	value will fail in the expected way.
		1007
		1008	If this call isn't available because your OS lacks it or it couldn't
		1009	be detected, it will be emulated by calling "fsync" instead.
		1010
		1011	IO::AIO::CWD
		1012	This is a compiletime constant (object) that represents the process
		1013	current working directory.
		1014
		1015	Specifying this object as working directory object for a pathname is
		1016	as if the pathname would be specified directly, without a directory
		1017	object, e.g., these calls are functionally identical:
		1018
		1019	aio_stat "somefile", sub { ... };
		1020	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
683		1021
684	IO::AIO::REQ CLASS	1022	IO::AIO::REQ CLASS
685	All non-aggregate "aio_*" functions return an object of this class when	1023	All non-aggregate "aio_*" functions return an object of this class when
686	called in non-void context.	1024	called in non-void context.
687		1025
…		…
761	$grp->cancel_subs	1099	$grp->cancel_subs
762	Cancel all subrequests and clears any feeder, but not the group	1100	Cancel all subrequests and clears any feeder, but not the group
763	request itself. Useful when you queued a lot of events but got a	1101	request itself. Useful when you queued a lot of events but got a
764	result early.	1102	result early.
765		1103
		1104	The group request will finish normally (you cannot add requests to
		1105	the group).
		1106
766	$grp->result (...)	1107	$grp->result (...)
767	Set the result value(s) that will be passed to the group callback	1108	Set the result value(s) that will be passed to the group callback
768	when all subrequests have finished and set the groups errno to the	1109	when all subrequests have finished and set the groups errno to the
769	current value of errno (just like calling "errno" without an error	1110	current value of errno (just like calling "errno" without an error
770	number). By default, no argument will be passed and errno is zero.	1111	number). By default, no argument will be passed and errno is zero.
…		…
784	Sets a feeder/generator on this group: every group can have an	1125	Sets a feeder/generator on this group: every group can have an
785	attached generator that generates requests if idle. The idea behind	1126	attached generator that generates requests if idle. The idea behind
786	this is that, although you could just queue as many requests as you	1127	this is that, although you could just queue as many requests as you
787	want in a group, this might starve other requests for a potentially	1128	want in a group, this might starve other requests for a potentially
788	long time. For example, "aio_scandir" might generate hundreds of	1129	long time. For example, "aio_scandir" might generate hundreds of
789	thousands "aio_stat" requests, delaying any later requests for a	1130	thousands of "aio_stat" requests, delaying any later requests for a
790	long time.	1131	long time.
791		1132
792	To avoid this, and allow incremental generation of requests, you can	1133	To avoid this, and allow incremental generation of requests, you can
793	instead a group and set a feeder on it that generates those	1134	instead a group and set a feeder on it that generates those
794	requests. The feed callback will be called whenever there are few	1135	requests. The feed callback will be called whenever there are few
…		…
837		1178
838	See "poll_cb" for an example.	1179	See "poll_cb" for an example.
839		1180
840	IO::AIO::poll_cb	1181	IO::AIO::poll_cb
841	Process some outstanding events on the result pipe. You have to call	1182	Process some outstanding events on the result pipe. You have to call
842	this regularly. Returns 0 if all events could be processed, or -1 if	1183	this regularly. Returns 0 if all events could be processed (or there
843	it returned earlier for whatever reason. Returns immediately when no	1184	were no events to process), or -1 if it returned earlier for
844	events are outstanding. The amount of events processed depends on	1185	whatever reason. Returns immediately when no events are outstanding.
845	the settings of "IO::AIO::max_poll_req" and	1186	The amount of events processed depends on the settings of
846	"IO::AIO::max_poll_time".	1187	"IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".
847		1188
848	If not all requests were processed for whatever reason, the	1189	If not all requests were processed for whatever reason, the
849	filehandle will still be ready when "poll_cb" returns, so normally	1190	filehandle will still be ready when "poll_cb" returns, so normally
850	you don't have to do anything special to have it called later.	1191	you don't have to do anything special to have it called later.
851		1192
		1193	Apart from calling "IO::AIO::poll_cb" when the event filehandle
		1194	becomes ready, it can be beneficial to call this function from loops
		1195	which submit a lot of requests, to make sure the results get
		1196	processed when they become available and not just when the loop is
		1197	finished and the event loop takes over again. This function returns
		1198	very fast when there are no outstanding requests.
		1199
852	Example: Install an Event watcher that automatically calls	1200	Example: Install an Event watcher that automatically calls
853	IO::AIO::poll_cb with high priority (more examples can be found in	1201	IO::AIO::poll_cb with high priority (more examples can be found in
854	the SYNOPSIS section, at the top of this document):	1202	the SYNOPSIS section, at the top of this document):
855		1203
856	Event->io (fd => IO::AIO::poll_fileno,	1204	Event->io (fd => IO::AIO::poll_fileno,
857	poll => 'r', async => 1,	1205	poll => 'r', async => 1,
858	cb => \&IO::AIO::poll_cb);	1206	cb => \&IO::AIO::poll_cb);
		1207
		1208	IO::AIO::poll_wait
		1209	If there are any outstanding requests and none of them in the result
		1210	phase, wait till the result filehandle becomes ready for reading
		1211	(simply does a "select" on the filehandle. This is useful if you
		1212	want to synchronously wait for some requests to finish).
		1213
		1214	See "nreqs" for an example.
		1215
		1216	IO::AIO::poll
		1217	Waits until some requests have been handled.
		1218
		1219	Returns the number of requests processed, but is otherwise strictly
		1220	equivalent to:
		1221
		1222	IO::AIO::poll_wait, IO::AIO::poll_cb
		1223
		1224	IO::AIO::flush
		1225	Wait till all outstanding AIO requests have been handled.
		1226
		1227	Strictly equivalent to:
		1228
		1229	IO::AIO::poll_wait, IO::AIO::poll_cb
		1230	while IO::AIO::nreqs;
859		1231
860	IO::AIO::max_poll_reqs $nreqs	1232	IO::AIO::max_poll_reqs $nreqs
861	IO::AIO::max_poll_time $seconds	1233	IO::AIO::max_poll_time $seconds
862	These set the maximum number of requests (default 0, meaning	1234	These set the maximum number of requests (default 0, meaning
863	infinity) that are being processed by "IO::AIO::poll_cb" in one	1235	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
887	# use a low priority so other tasks have priority	1259	# use a low priority so other tasks have priority
888	Event->io (fd => IO::AIO::poll_fileno,	1260	Event->io (fd => IO::AIO::poll_fileno,
889	poll => 'r', nice => 1,	1261	poll => 'r', nice => 1,
890	cb => &IO::AIO::poll_cb);	1262	cb => &IO::AIO::poll_cb);
891		1263
892	IO::AIO::poll_wait
893	If there are any outstanding requests and none of them in the result
894	phase, wait till the result filehandle becomes ready for reading
895	(simply does a "select" on the filehandle. This is useful if you
896	want to synchronously wait for some requests to finish).
897
898	See "nreqs" for an example.
899
900	IO::AIO::poll
901	Waits until some requests have been handled.
902
903	Returns the number of requests processed, but is otherwise strictly
904	equivalent to:
905
906	IO::AIO::poll_wait, IO::AIO::poll_cb
907
908	IO::AIO::flush
909	Wait till all outstanding AIO requests have been handled.
910
911	Strictly equivalent to:
912
913	IO::AIO::poll_wait, IO::AIO::poll_cb
914	while IO::AIO::nreqs;
915
916	CONTROLLING THE NUMBER OF THREADS	1264	CONTROLLING THE NUMBER OF THREADS
917	IO::AIO::min_parallel $nthreads	1265	IO::AIO::min_parallel $nthreads
918	Set the minimum number of AIO threads to $nthreads. The current	1266	Set the minimum number of AIO threads to $nthreads. The current
919	default is 8, which means eight asynchronous operations can execute	1267	default is 8, which means eight asynchronous operations can execute
920	concurrently at any one time (the number of outstanding requests,	1268	concurrently at any one time (the number of outstanding requests,
…		…
949		1297
950	Under normal circumstances you don't need to call this function.	1298	Under normal circumstances you don't need to call this function.
951		1299
952	IO::AIO::max_idle $nthreads	1300	IO::AIO::max_idle $nthreads
953	Limit the number of threads (default: 4) that are allowed to idle	1301	Limit the number of threads (default: 4) that are allowed to idle
954	(i.e., threads that did not get a request to process within 10	1302	(i.e., threads that did not get a request to process within the idle
955	seconds). That means if a thread becomes idle while $nthreads other	1303	timeout (default: 10 seconds). That means if a thread becomes idle
956	threads are also idle, it will free its resources and exit.	1304	while $nthreads other threads are also idle, it will free its
		1305	resources and exit.
957		1306
958	This is useful when you allow a large number of threads (e.g. 100 or	1307	This is useful when you allow a large number of threads (e.g. 100 or
959	1000) to allow for extremely high load situations, but want to free	1308	1000) to allow for extremely high load situations, but want to free
960	resources under normal circumstances (1000 threads can easily	1309	resources under normal circumstances (1000 threads can easily
961	consume 30MB of RAM).	1310	consume 30MB of RAM).
962		1311
963	The default is probably ok in most situations, especially if thread	1312	The default is probably ok in most situations, especially if thread
964	creation is fast. If thread creation is very slow on your system you	1313	creation is fast. If thread creation is very slow on your system you
965	might want to use larger values.	1314	might want to use larger values.
966		1315
		1316	IO::AIO::idle_timeout $seconds
		1317	Sets the minimum idle timeout (default 10) after which worker
		1318	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1319
967	IO::AIO::max_outstanding $maxreqs	1320	IO::AIO::max_outstanding $maxreqs
		1321	Sets the maximum number of outstanding requests to $nreqs. If you do
		1322	queue up more than this number of requests, the next call to
		1323	"IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
		1324	"IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
		1325	no longer exceeded.
		1326
		1327	In other words, this setting does not enforce a queue limit, but can
		1328	be used to make poll functions block if the limit is exceeded.
		1329
968	This is a very bad function to use in interactive programs because	1330	This is a very bad function to use in interactive programs because
969	it blocks, and a bad way to reduce concurrency because it is	1331	it blocks, and a bad way to reduce concurrency because it is
970	inexact: Better use an "aio_group" together with a feed callback.	1332	inexact: Better use an "aio_group" together with a feed callback.
971		1333
972	Sets the maximum number of outstanding requests to $nreqs. If you do	1334	It's main use is in scripts without an event loop - when you want to
973	queue up more than this number of requests, the next call to the	1335	stat a lot of files, you can write somehting like this:
974	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
975	function will block until the limit is no longer exceeded.
976		1336
977	The default value is very large, so there is no practical limit on	1337	IO::AIO::max_outstanding 32;
		1338
		1339	for my $path (...) {
		1340	aio_stat $path , ...;
		1341	IO::AIO::poll_cb;
		1342	}
		1343
		1344	IO::AIO::flush;
		1345
		1346	The call to "poll_cb" inside the loop will normally return
		1347	instantly, but as soon as more thna 32 reqeusts are in-flight, it
		1348	will block until some requests have been handled. This keeps the
		1349	loop from pushing a large number of "aio_stat" requests onto the
		1350	queue.
		1351
		1352	The default value for "max_outstanding" is very large, so there is
978	the number of outstanding requests.	1353	no practical limit on the number of outstanding requests.
979
980	You can still queue as many requests as you want. Therefore,
981	"max_outstanding" is mainly useful in simple scripts (with low
982	values) or as a stop gap to shield against fatal memory overflow
983	(with large values).
984		1354
985	STATISTICAL INFORMATION	1355	STATISTICAL INFORMATION
986	IO::AIO::nreqs	1356	IO::AIO::nreqs
987	Returns the number of requests currently in the ready, execute or	1357	Returns the number of requests currently in the ready, execute or
988	pending states (i.e. for which their callback has not been invoked	1358	pending states (i.e. for which their callback has not been invoked
…		…
1012	set to non-blocking operations).	1382	set to non-blocking operations).
1013		1383
1014	Returns the number of bytes copied, or -1 on error.	1384	Returns the number of bytes copied, or -1 on error.
1015		1385
1016	IO::AIO::fadvise $fh, $offset, $len, $advice	1386	IO::AIO::fadvise $fh, $offset, $len, $advice
1017	Simply calls the "posix_fadvise" function (see it's manpage for	1387	Simply calls the "posix_fadvise" function (see its manpage for
1018	details). The following advice constants are avaiable:	1388	details). The following advice constants are available:
1019	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",	1389	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1020	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",	1390	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1021	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".	1391	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1022		1392
1023	On systems that do not implement "posix_fadvise", this function	1393	On systems that do not implement "posix_fadvise", this function
1024	returns ENOSYS, otherwise the return value of "posix_fadvise".	1394	returns ENOSYS, otherwise the return value of "posix_fadvise".
1025		1395
		1396	IO::AIO::madvise $scalar, $offset, $len, $advice
		1397	Simply calls the "posix_madvise" function (see its manpage for
		1398	details). The following advice constants are available:
		1399	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1400	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1401	"IO::AIO::MADV_DONTNEED".
		1402
		1403	On systems that do not implement "posix_madvise", this function
		1404	returns ENOSYS, otherwise the return value of "posix_madvise".
		1405
		1406	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1407	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1408	$scalar (see its manpage for details). The following protect
		1409	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1410	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1411
		1412	On systems that do not implement "mprotect", this function returns
		1413	ENOSYS, otherwise the return value of "mprotect".
		1414
		1415	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1416	Memory-maps a file (or anonymous memory range) and attaches it to
		1417	the given $scalar, which will act like a string scalar.
		1418
		1419	The only operations allowed on the scalar are "substr"/"vec" that
		1420	don't change the string length, and most read-only operations such
		1421	as copying it or searching it with regexes and so on.
		1422
		1423	Anything else is unsafe and will, at best, result in memory leaks.
		1424
		1425	The memory map associated with the $scalar is automatically removed
		1426	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1427	"IO::AIO::munmap" functions are called.
		1428
		1429	This calls the "mmap"(2) function internally. See your system's
		1430	manual page for details on the $length, $prot and $flags parameters.
		1431
		1432	The $length must be larger than zero and smaller than the actual
		1433	filesize.
		1434
		1435	$prot is a combination of "IO::AIO::PROT_NONE",
		1436	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1437	"IO::AIO::PROT_WRITE",
		1438
		1439	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1440	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1441	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1442	(which is set to "MAP_ANON" if your system only provides this
		1443	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1444	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1445	"IO::AIO::MAP_NONBLOCK"
		1446
		1447	If $fh is "undef", then a file descriptor of -1 is passed.
		1448
		1449	$offset is the offset from the start of the file - it generally must
		1450	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1451
		1452	Example:
		1453
		1454	use Digest::MD5;
		1455	use IO::AIO;
		1456
		1457	open my $fh, "<verybigfile"
		1458	or die "$!";
		1459
		1460	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1461	or die "verybigfile: $!";
		1462
		1463	my $fast_md5 = md5 $data;
		1464
		1465	IO::AIO::munmap $scalar
		1466	Removes a previous mmap and undefines the $scalar.
		1467
		1468	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1469	Calls the "munlock" function, undoing the effects of a previous
		1470	"aio_mlock" call (see its description for details).
		1471
		1472	IO::AIO::munlockall
		1473	Calls the "munlockall" function.
		1474
		1475	On systems that do not implement "munlockall", this function returns
		1476	ENOSYS, otherwise the return value of "munlockall".
		1477
		1478	EVENT LOOP INTEGRATION
		1479	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1480	automatically into many event loops:
		1481
		1482	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1483	use AnyEvent::AIO;
		1484
		1485	You can also integrate IO::AIO manually into many event loops, here are
		1486	some examples of how to do this:
		1487
		1488	# EV integration
		1489	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1490
		1491	# Event integration
		1492	Event->io (fd => IO::AIO::poll_fileno,
		1493	poll => 'r',
		1494	cb => \&IO::AIO::poll_cb);
		1495
		1496	# Glib/Gtk2 integration
		1497	add_watch Glib::IO IO::AIO::poll_fileno,
		1498	in => sub { IO::AIO::poll_cb; 1 };
		1499
		1500	# Tk integration
		1501	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1502	readable => \&IO::AIO::poll_cb);
		1503
		1504	# Danga::Socket integration
		1505	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1506	\&IO::AIO::poll_cb);
		1507
1026	FORK BEHAVIOUR	1508	FORK BEHAVIOUR
1027	This module should do "the right thing" when the process using it forks:	1509	Usage of pthreads in a program changes the semantics of fork
		1510	considerably. Specifically, only async-safe functions can be called
		1511	after fork. Perl doesn't know about this, so in general, you cannot call
		1512	fork with defined behaviour in perl if pthreads are involved. IO::AIO
		1513	uses pthreads, so this applies, but many other extensions and (for
		1514	inexplicable reasons) perl itself often is linked against pthreads, so
		1515	this limitation applies to quite a lot of perls.
1028		1516
1029	Before the fork, IO::AIO enters a quiescent state where no requests can	1517	This module no longer tries to fight your OS, or POSIX. That means
1030	be added in other threads and no results will be processed. After the	1518	IO::AIO only works in the process that loaded it. Forking is fully
1031	fork the parent simply leaves the quiescent state and continues	1519	supported, but using IO::AIO in the child is not.
1032	request/result processing, while the child frees the request/result
1033	queue (so that the requests started before the fork will only be handled
1034	in the parent). Threads will be started on demand until the limit set in
1035	the parent process has been reached again.
1036		1520
1037	In short: the parent will, after a short pause, continue as if fork had	1521	You might get around by not using IO::AIO before (or after) forking.
1038	not been called, while the child will act as if IO::AIO has not been	1522	You could also try to call the IO::AIO::reinit function in the child:
1039	used yet.	1523
		1524	IO::AIO::reinit
		1525	Abandons all current requests and I/O threads and simply
		1526	reinitialises all data structures. This is not an operation
		1527	supported by any standards, but happens to work on GNU/Linux and
		1528	some newer BSD systems.
		1529
		1530	The only reasonable use for this function is to call it after
		1531	forking, if "IO::AIO" was used in the parent. Calling it while
		1532	IO::AIO is active in the process will result in undefined behaviour.
		1533	Calling it at any time will also result in any undefined (by POSIX)
		1534	behaviour.
1040		1535
1041	MEMORY USAGE	1536	MEMORY USAGE
1042	Per-request usage:	1537	Per-request usage:
1043		1538
1044	Each aio request uses - depending on your architecture - around 100-200	1539	Each aio request uses - depending on your architecture - around 100-200

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Comparing IO-AIO/README (file contents): Revision 1.39 by root, Wed Aug 5 11:53:16 2009 UTC vs. Revision 1.50 by root, Sun Oct 9 08:24:49 2011 UTC

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Comparing IO-AIO/README (file contents):
Revision 1.39 by root, Wed Aug 5 11:53:16 2009 UTC vs.
Revision 1.50 by root, Sun Oct 9 08:24:49 2011 UTC