ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.151 by root, Fri Jun 12 00:43:16 2009 UTC vs.
Revision 1.264 by root, Mon Jul 18 07:48:01 2016 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my $fh = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
26	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
27		27
28	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
29	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
30		30
31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32	use AnyEvent::AIO;
33
34	# EV integration
35	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37	# Event integration
38	Event->io (fd => IO::AIO::poll_fileno,
39	poll => 'r',
40	cb => \&IO::AIO::poll_cb);
41
42	# Glib/Gtk2 integration
43	add_watch Glib::IO IO::AIO::poll_fileno,
44	in => sub { IO::AIO::poll_cb; 1 };
45
46	# Tk integration
47	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48	readable => \&IO::AIO::poll_cb);
49
50	# Danga::Socket integration
51	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52	\&IO::AIO::poll_cb);
53
54	=head1 DESCRIPTION	31	=head1 DESCRIPTION
55		32
56	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
57	operating system supports.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
58		36
59	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
60	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
61	will still block, but you can do something else in the meantime. This	39	will still block, but you can do something else in the meantime. This
62	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
66	on a RAID volume or over NFS when you do a number of stat operations	44	on a RAID volume or over NFS when you do a number of stat operations
67	concurrently.	45	concurrently.
68		46
69	While most of this works on all types of file descriptors (for	47	While most of this works on all types of file descriptors (for
70	example sockets), using these functions on file descriptors that	48	example sockets), using these functions on file descriptors that
71	support nonblocking operation (again, sockets, pipes etc.) is very	49	support nonblocking operation (again, sockets, pipes etc.) is
72	inefficient. Use an event loop for that (such as the L<Event|Event>	50	very inefficient. Use an event loop for that (such as the L<EV>
73	module): IO::AIO will naturally fit into such an event loop itself.	51	module): IO::AIO will naturally fit into such an event loop itself.
74		52
75	In this version, a number of threads are started that execute your	53	In this version, a number of threads are started that execute your
76	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
77	in perl, and the threads created by this module will not be visible	55	in perl, and the threads created by this module will not be visible
…		…
87	yourself, always call C<poll_cb> from within the same thread, or never	65	yourself, always call C<poll_cb> from within the same thread, or never
88	call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
89		67
90	=head2 EXAMPLE	68	=head2 EXAMPLE
91		69
92	This is a simple example that uses the Event module and loads	70	This is a simple example that uses the EV module and loads
93	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
94		72
95	use Fcntl;
96	use Event;	73	use EV;
97	use IO::AIO;	74	use IO::AIO;
98		75
99	# register the IO::AIO callback with Event	76	# register the IO::AIO callback with EV
100	Event->io (fd => IO::AIO::poll_fileno,	77	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
101	poll => 'r',
102	cb => \&IO::AIO::poll_cb);
103		78
104	# queue the request to open /etc/passwd	79	# queue the request to open /etc/passwd
105	aio_open "/etc/passwd", O_RDONLY, 0, sub {	80	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106	my $fh = shift	81	my $fh = shift
107	or die "error while opening: $!";	82	or die "error while opening: $!";
108		83
109	# stat'ing filehandles is generally non-blocking	84	# stat'ing filehandles is generally non-blocking
110	my $size = -s $fh;	85	my $size = -s $fh;
…		…
119		94
120	# file contents now in $contents	95	# file contents now in $contents
121	print $contents;	96	print $contents;
122		97
123	# exit event loop and program	98	# exit event loop and program
124	Event::unloop;	99	EV::break;
125	};	100	};
126	};	101	};
127		102
128	# possibly queue up other requests, or open GUI windows,	103	# possibly queue up other requests, or open GUI windows,
129	# check for sockets etc. etc.	104	# check for sockets etc. etc.
130		105
131	# process events as long as there are some:	106	# process events as long as there are some:
132	Event::loop;	107	EV::run;
133		108
134	=head1 REQUEST ANATOMY AND LIFETIME	109	=head1 REQUEST ANATOMY AND LIFETIME
135		110
136	Every C<aio_*> function creates a request. which is a C data structure not	111	Every C<aio_*> function creates a request. which is a C data structure not
137	directly visible to Perl.	112	directly visible to Perl.
…		…
187		162
188	package IO::AIO;	163	package IO::AIO;
189		164
190	use Carp ();	165	use Carp ();
191		166
192	no warnings;	167	use common::sense;
193	use strict 'vars';
194		168
195	use base 'Exporter';	169	use base 'Exporter';
196		170
197	BEGIN {	171	BEGIN {
198	our $VERSION = '3.2';	172	our $VERSION = 4.34;
199		173
200	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	174	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
201	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	175	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	176	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
203	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	177	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		178	aio_pathsync aio_readahead aio_fiemap aio_allocate
204	aio_rename aio_link aio_move aio_copy aio_group	179	aio_rename aio_link aio_move aio_copy aio_group
205	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206	aio_chmod aio_utime aio_truncate);	181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
		183	aio_statvfs
		184	aio_wd);
207		185
208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	186	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	187	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210	min_parallel max_parallel max_idle	188	min_parallel max_parallel max_idle idle_timeout
211	nreqs nready npending nthreads	189	nreqs nready npending nthreads
212	max_poll_time max_poll_reqs);	190	max_poll_time max_poll_reqs
		191	sendfile fadvise madvise
		192	mmap munmap munlock munlockall);
213		193
214	push @AIO_REQ, qw(aio_busy); # not exported	194	push @AIO_REQ, qw(aio_busy); # not exported
215		195
216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217		197
…		…
219	XSLoader::load ("IO::AIO", $VERSION);	199	XSLoader::load ("IO::AIO", $VERSION);
220	}	200	}
221		201
222	=head1 FUNCTIONS	202	=head1 FUNCTIONS
223		203
224	=head2 AIO REQUEST FUNCTIONS	204	=head2 QUICK OVERVIEW
		205
		206	This section simply lists the prototypes most of the functions for
		207	quick reference. See the following sections for function-by-function
		208	documentation.
		209
		210	aio_wd $pathname, $callback->($wd)
		211	aio_open $pathname, $flags, $mode, $callback->($fh)
		212	aio_close $fh, $callback->($status)
		213	aio_seek $fh,$offset,$whence, $callback->($offs)
		214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		217	aio_readahead $fh,$offset,$length, $callback->($retval)
		218	aio_stat $fh_or_path, $callback->($status)
		219	aio_lstat $fh, $callback->($status)
		220	aio_statvfs $fh_or_path, $callback->($statvfs)
		221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		223	aio_chmod $fh_or_path, $mode, $callback->($status)
		224	aio_truncate $fh_or_path, $offset, $callback->($status)
		225	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		226	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		227	aio_unlink $pathname, $callback->($status)
		228	aio_mknod $pathname, $mode, $dev, $callback->($status)
		229	aio_link $srcpath, $dstpath, $callback->($status)
		230	aio_symlink $srcpath, $dstpath, $callback->($status)
		231	aio_readlink $pathname, $callback->($link)
		232	aio_realpath $pathname, $callback->($path)
		233	aio_rename $srcpath, $dstpath, $callback->($status)
		234	aio_mkdir $pathname, $mode, $callback->($status)
		235	aio_rmdir $pathname, $callback->($status)
		236	aio_readdir $pathname, $callback->($entries)
		237	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		238	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		239	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		240	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		241	aio_load $pathname, $data, $callback->($status)
		242	aio_copy $srcpath, $dstpath, $callback->($status)
		243	aio_move $srcpath, $dstpath, $callback->($status)
		244	aio_rmtree $pathname, $callback->($status)
		245	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		246	aio_ioctl $fh, $request, $buf, $callback->($status)
		247	aio_sync $callback->($status)
		248	aio_syncfs $fh, $callback->($status)
		249	aio_fsync $fh, $callback->($status)
		250	aio_fdatasync $fh, $callback->($status)
		251	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		252	aio_pathsync $pathname, $callback->($status)
		253	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		254	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		255	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		256	aio_mlockall $flags, $callback->($status)
		257	aio_group $callback->(...)
		258	aio_nop $callback->()
		259
		260	$prev_pri = aioreq_pri [$pri]
		261	aioreq_nice $pri_adjust
		262
		263	IO::AIO::poll_wait
		264	IO::AIO::poll_cb
		265	IO::AIO::poll
		266	IO::AIO::flush
		267	IO::AIO::max_poll_reqs $nreqs
		268	IO::AIO::max_poll_time $seconds
		269	IO::AIO::min_parallel $nthreads
		270	IO::AIO::max_parallel $nthreads
		271	IO::AIO::max_idle $nthreads
		272	IO::AIO::idle_timeout $seconds
		273	IO::AIO::max_outstanding $maxreqs
		274	IO::AIO::nreqs
		275	IO::AIO::nready
		276	IO::AIO::npending
		277
		278	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		279	IO::AIO::fadvise $fh, $offset, $len, $advice
		280	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		281	IO::AIO::munmap $scalar
		282	IO::AIO::madvise $scalar, $offset, $length, $advice
		283	IO::AIO::mprotect $scalar, $offset, $length, $protect
		284	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		285	IO::AIO::munlockall
		286
		287	=head2 API NOTES
225		288
226	All the C<aio_*> calls are more or less thin wrappers around the syscall	289	All the C<aio_*> calls are more or less thin wrappers around the syscall
227	with the same name (sans C<aio_>). The arguments are similar or identical,	290	with the same name (sans C<aio_>). The arguments are similar or identical,
228	and they all accept an additional (and optional) C<$callback> argument	291	and they all accept an additional (and optional) C<$callback> argument
229	which must be a code reference. This code reference will get called with	292	which must be a code reference. This code reference will be called after
230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	293	the syscall has been executed in an asynchronous fashion. The results
231	perl, which usually delivers "false") as its sole argument after the given	294	of the request will be passed as arguments to the callback (and, if an
232	syscall has been executed asynchronously.	295	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		296	most syscalls return C<-1> on error, unlike perl, which usually delivers
		297	"false").
		298
		299	Some requests (such as C<aio_readdir>) pass the actual results and
		300	communicate failures by passing C<undef>.
233		301
234	All functions expecting a filehandle keep a copy of the filehandle	302	All functions expecting a filehandle keep a copy of the filehandle
235	internally until the request has finished.	303	internally until the request has finished.
236		304
237	All functions return request objects of type L<IO::AIO::REQ> that allow	305	All functions return request objects of type L<IO::AIO::REQ> that allow
238	further manipulation of those requests while they are in-flight.	306	further manipulation of those requests while they are in-flight.
239		307
240	The pathnames you pass to these routines I<must> be absolute and	308	The pathnames you pass to these routines I<should> be absolute. The
241	encoded as octets. The reason for the former is that at the time the	309	reason for this is that at the time the request is being executed, the
242	request is being executed, the current working directory could have	310	current working directory could have changed. Alternatively, you can
243	changed. Alternatively, you can make sure that you never change the	311	make sure that you never change the current working directory anywhere
244	current working directory anywhere in the program and then use relative	312	in the program and then use relative paths. You can also take advantage
245	paths.	313	of IO::AIOs working directory abstraction, that lets you specify paths
		314	relative to some previously-opened "working directory object" - see the
		315	description of the C<IO::AIO::WD> class later in this document.
246		316
247	To encode pathnames as octets, either make sure you either: a) always pass	317	To encode pathnames as octets, either make sure you either: a) always pass
248	in filenames you got from outside (command line, readdir etc.) without	318	in filenames you got from outside (command line, readdir etc.) without
249	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	319	tinkering, b) are in your native filesystem encoding, c) use the Encode
250	your pathnames to the locale (or other) encoding in effect in the user	320	module and encode your pathnames to the locale (or other) encoding in
251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	321	effect in the user environment, d) use Glib::filename_from_unicode on
252	use something else to ensure your scalar has the correct contents.	322	unicode filenames or e) use something else to ensure your scalar has the
		323	correct contents.
253		324
254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	325	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255	handles correctly whether it is set or not.	326	handles correctly whether it is set or not.
		327
		328	=head2 AIO REQUEST FUNCTIONS
256		329
257	=over 4	330	=over 4
258		331
259	=item $prev_pri = aioreq_pri [$pri]	332	=item $prev_pri = aioreq_pri [$pri]
260		333
…		…
290		363
291		364
292	=item aio_open $pathname, $flags, $mode, $callback->($fh)	365	=item aio_open $pathname, $flags, $mode, $callback->($fh)
293		366
294	Asynchronously open or create a file and call the callback with a newly	367	Asynchronously open or create a file and call the callback with a newly
295	created filehandle for the file.	368	created filehandle for the file (or C<undef> in case of an error).
296		369
297	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	370	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
298	for an explanation.	371	for an explanation.
299		372
300	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	373	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
307	by the umask in effect then the request is being executed, so better never	380	by the umask in effect then the request is being executed, so better never
308	change the umask.	381	change the umask.
309		382
310	Example:	383	Example:
311		384
312	aio_open "/etc/passwd", O_RDONLY, 0, sub {	385	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313	if ($_[0]) {	386	if ($_[0]) {
314	print "open successful, fh is $_[0]\n";	387	print "open successful, fh is $_[0]\n";
315	...	388	...
316	} else {	389	} else {
317	die "open failed: $!\n";	390	die "open failed: $!\n";
318	}	391	}
319	};	392	};
320		393
		394	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		395	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		396	following POSIX and non-POSIX constants are available (missing ones on
		397	your system are, as usual, C<0>):
		398
		399	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		400	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		401	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		402
321		403
322	=item aio_close $fh, $callback->($status)	404	=item aio_close $fh, $callback->($status)
323		405
324	Asynchronously close a file and call the callback with the result	406	Asynchronously close a file and call the callback with the result
325	code.	407	code.
…		…
333		415
334	Or in other words: the file descriptor will be closed, but it will not be	416	Or in other words: the file descriptor will be closed, but it will not be
335	free for reuse until the perl filehandle is closed.	417	free for reuse until the perl filehandle is closed.
336		418
337	=cut	419	=cut
		420
		421	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		422
		423	Seeks the filehandle to the new C<$offset>, similarly to perl's
		424	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		425	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		426	C<IO::AIO::SEEK_END>).
		427
		428	The resulting absolute offset will be passed to the callback, or C<-1> in
		429	case of an error.
		430
		431	In theory, the C<$whence> constants could be different than the
		432	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		433	so don't panic.
		434
		435	As a GNU/Linux (and maybe Solaris) extension, also the constants
		436	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		437	could be found. No guarantees about suitability for use in C<aio_seek> or
		438	Perl's C<sysseek> can be made though, although I would naively assume they
		439	"just work".
338		440
339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	441	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		442
341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	443	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342		444
…		…
375		477
376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	478	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377	reading at byte offset C<$in_offset>, and starts writing at the current	479	reading at byte offset C<$in_offset>, and starts writing at the current
378	file offset of C<$out_fh>. Because of that, it is not safe to issue more	480	file offset of C<$out_fh>. Because of that, it is not safe to issue more
379	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	481	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380	other.	482	other. The same C<$in_fh> works fine though, as this function does not
		483	move or use the file offset of C<$in_fh>.
381		484
		485	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		486	are written, and there is no way to find out how many more bytes have been
		487	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		488	number of bytes written to C<$out_fh>. Only if the result value equals
		489	C<$length> one can assume that C<$length> bytes have been read.
		490
		491	Unlike with other C<aio_> functions, it makes a lot of sense to use
		492	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		493	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		494	the socket I/O will be non-blocking. Note, however, that you can run
		495	into a trap where C<aio_sendfile> reads some data with readahead, then
		496	fails to write all data, and when the socket is ready the next time, the
		497	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		498	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		499	resource usage.
		500
382	This call tries to make use of a native C<sendfile> syscall to provide	501	This call tries to make use of a native C<sendfile>-like syscall to
383	zero-copy operation. For this to work, C<$out_fh> should refer to a	502	provide zero-copy operation. For this to work, C<$out_fh> should refer to
384	socket, and C<$in_fh> should refer to mmap'able file.	503	a socket, and C<$in_fh> should refer to an mmap'able file.
385		504
386	If the native sendfile call fails or is not implemented, it will be	505	If a native sendfile cannot be found or it fails with C<ENOSYS>,
387	emulated, so you can call C<aio_sendfile> on any type of filehandle	506	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		507	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
388	regardless of the limitations of the operating system.	508	type of filehandle regardless of the limitations of the operating system.
389		509
390	Please note, however, that C<aio_sendfile> can read more bytes from	510	As native sendfile syscalls (as practically any non-POSIX interface hacked
391	C<$in_fh> than are written, and there is no way to find out how many	511	together in a hurry to improve benchmark numbers) tend to be rather buggy
392	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	512	on many systems, this implementation tries to work around some known bugs
393	provides the number of bytes written to C<$out_fh>. Only if the result	513	in Linux and FreeBSD kernels (probably others, too), but that might fail,
394	value equals C<$length> one can assume that C<$length> bytes have been	514	so you really really should check the return value of C<aio_sendfile> -
395	read.	515	fewer bytes than expected might have been transferred.
396		516
397		517
398	=item aio_readahead $fh,$offset,$length, $callback->($retval)	518	=item aio_readahead $fh,$offset,$length, $callback->($retval)
399		519
400	C<aio_readahead> populates the page cache with data from a file so that	520	C<aio_readahead> populates the page cache with data from a file so that
…		…
404	whole pages, so that offset is effectively rounded down to a page boundary	524	whole pages, so that offset is effectively rounded down to a page boundary
405	and bytes are read up to the next page boundary greater than or equal to	525	and bytes are read up to the next page boundary greater than or equal to
406	(off-set+length). C<aio_readahead> does not read beyond the end of the	526	(off-set+length). C<aio_readahead> does not read beyond the end of the
407	file. The current file offset of the file is left unchanged.	527	file. The current file offset of the file is left unchanged.
408		528
409	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	529	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
410	emulated by simply reading the data, which would have a similar effect.	530	be emulated by simply reading the data, which would have a similar effect.
411		531
412		532
413	=item aio_stat $fh_or_path, $callback->($status)	533	=item aio_stat $fh_or_path, $callback->($status)
414		534
415	=item aio_lstat $fh, $callback->($status)	535	=item aio_lstat $fh, $callback->($status)
…		…
422	for an explanation.	542	for an explanation.
423		543
424	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	544	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
425	error when stat'ing a large file, the results will be silently truncated	545	error when stat'ing a large file, the results will be silently truncated
426	unless perl itself is compiled with large file support.	546	unless perl itself is compiled with large file support.
		547
		548	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		549	following constants and functions (if not implemented, the constants will
		550	be C<0> and the functions will either C<croak> or fall back on traditional
		551	behaviour).
		552
		553	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		554	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		555	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
427		556
428	Example: Print the length of F</etc/passwd>:	557	Example: Print the length of F</etc/passwd>:
429		558
430	aio_stat "/etc/passwd", sub {	559	aio_stat "/etc/passwd", sub {
431	$_[0] and die "stat failed: $!";	560	$_[0] and die "stat failed: $!";
432	print "size is ", -s _, "\n";	561	print "size is ", -s _, "\n";
433	};	562	};
434		563
435		564
		565	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		566
		567	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		568	whether a file handle or path was passed.
		569
		570	On success, the callback is passed a hash reference with the following
		571	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		572	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		573	is passed.
		574
		575	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		576	C<ST_NOSUID>.
		577
		578	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		579	their correct value when available, or to C<0> on systems that do
		580	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		581	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		582	C<ST_NODIRATIME> and C<ST_RELATIME>.
		583
		584	Example: stat C</wd> and dump out the data if successful.
		585
		586	aio_statvfs "/wd", sub {
		587	my $f = $_[0]
		588	or die "statvfs: $!";
		589
		590	use Data::Dumper;
		591	say Dumper $f;
		592	};
		593
		594	# result:
		595	{
		596	bsize => 1024,
		597	bfree => 4333064312,
		598	blocks => 10253828096,
		599	files => 2050765568,
		600	flag => 4096,
		601	favail => 2042092649,
		602	bavail => 4333064312,
		603	ffree => 2042092649,
		604	namemax => 255,
		605	frsize => 1024,
		606	fsid => 1810
		607	}
		608
		609	Here is a (likely partial - send me updates!) list of fsid values used by
		610	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		611
		612	0x0000adf5 adfs
		613	0x0000adff affs
		614	0x5346414f afs
		615	0x09041934 anon-inode filesystem
		616	0x00000187 autofs
		617	0x42465331 befs
		618	0x1badface bfs
		619	0x42494e4d binfmt_misc
		620	0x9123683e btrfs
		621	0x0027e0eb cgroupfs
		622	0xff534d42 cifs
		623	0x73757245 coda
		624	0x012ff7b7 coh
		625	0x28cd3d45 cramfs
		626	0x453dcd28 cramfs-wend (wrong endianness)
		627	0x64626720 debugfs
		628	0x00001373 devfs
		629	0x00001cd1 devpts
		630	0x0000f15f ecryptfs
		631	0x00414a53 efs
		632	0x0000137d ext
		633	0x0000ef53 ext2/ext3/ext4
		634	0x0000ef51 ext2
		635	0xf2f52010 f2fs
		636	0x00004006 fat
		637	0x65735546 fuseblk
		638	0x65735543 fusectl
		639	0x0bad1dea futexfs
		640	0x01161970 gfs2
		641	0x47504653 gpfs
		642	0x00004244 hfs
		643	0xf995e849 hpfs
		644	0x00c0ffee hostfs
		645	0x958458f6 hugetlbfs
		646	0x2bad1dea inotifyfs
		647	0x00009660 isofs
		648	0x000072b6 jffs2
		649	0x3153464a jfs
		650	0x6b414653 k-afs
		651	0x0bd00bd0 lustre
		652	0x0000137f minix
		653	0x0000138f minix 30 char names
		654	0x00002468 minix v2
		655	0x00002478 minix v2 30 char names
		656	0x00004d5a minix v3
		657	0x19800202 mqueue
		658	0x00004d44 msdos
		659	0x0000564c novell
		660	0x00006969 nfs
		661	0x6e667364 nfsd
		662	0x00003434 nilfs
		663	0x5346544e ntfs
		664	0x00009fa1 openprom
		665	0x7461636F ocfs2
		666	0x00009fa0 proc
		667	0x6165676c pstorefs
		668	0x0000002f qnx4
		669	0x68191122 qnx6
		670	0x858458f6 ramfs
		671	0x52654973 reiserfs
		672	0x00007275 romfs
		673	0x67596969 rpc_pipefs
		674	0x73636673 securityfs
		675	0xf97cff8c selinux
		676	0x0000517b smb
		677	0x534f434b sockfs
		678	0x73717368 squashfs
		679	0x62656572 sysfs
		680	0x012ff7b6 sysv2
		681	0x012ff7b5 sysv4
		682	0x01021994 tmpfs
		683	0x15013346 udf
		684	0x00011954 ufs
		685	0x54190100 ufs byteswapped
		686	0x00009fa2 usbdevfs
		687	0x01021997 v9fs
		688	0xa501fcf5 vxfs
		689	0xabba1974 xenfs
		690	0x012ff7b4 xenix
		691	0x58465342 xfs
		692	0x012fd16d xia
		693
436	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	694	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437		695
438	Works like perl's C<utime> function (including the special case of $atime	696	Works like perl's C<utime> function (including the special case of $atime
439	and $mtime being undef). Fractional times are supported if the underlying	697	and $mtime being undef). Fractional times are supported if the underlying
440	syscalls support them.	698	syscalls support them.
…		…
467	=item aio_truncate $fh_or_path, $offset, $callback->($status)	725	=item aio_truncate $fh_or_path, $offset, $callback->($status)
468		726
469	Works like truncate(2) or ftruncate(2).	727	Works like truncate(2) or ftruncate(2).
470		728
471		729
		730	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		731
		732	Allocates or frees disk space according to the C<$mode> argument. See the
		733	linux C<fallocate> documentation for details.
		734
		735	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		736	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		737	to deallocate a file range.
		738
		739	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		740	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		741	your L<fallocate(2)> manpage).
		742
		743	The file system block size used by C<fallocate> is presumably the
		744	C<f_bsize> returned by C<statvfs>.
		745
		746	If C<fallocate> isn't available or cannot be emulated (currently no
		747	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		748
		749
472	=item aio_chmod $fh_or_path, $mode, $callback->($status)	750	=item aio_chmod $fh_or_path, $mode, $callback->($status)
473		751
474	Works like perl's C<chmod> function.	752	Works like perl's C<chmod> function.
475		753
476		754
…		…
478		756
479	Asynchronously unlink (delete) a file and call the callback with the	757	Asynchronously unlink (delete) a file and call the callback with the
480	result code.	758	result code.
481		759
482		760
483	=item aio_mknod $path, $mode, $dev, $callback->($status)	761	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
484		762
485	[EXPERIMENTAL]	763	[EXPERIMENTAL]
486		764
487	Asynchronously create a device node (or fifo). See mknod(2).	765	Asynchronously create a device node (or fifo). See mknod(2).
488		766
489	The only (POSIX-) portable way of calling this function is:	767	The only (POSIX-) portable way of calling this function is:
490		768
491	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	769	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492		770
		771	See C<aio_stat> for info about some potentially helpful extra constants
		772	and functions.
493		773
494	=item aio_link $srcpath, $dstpath, $callback->($status)	774	=item aio_link $srcpath, $dstpath, $callback->($status)
495		775
496	Asynchronously create a new link to the existing object at C<$srcpath> at	776	Asynchronously create a new link to the existing object at C<$srcpath> at
497	the path C<$dstpath> and call the callback with the result code.	777	the path C<$dstpath> and call the callback with the result code.
…		…
501		781
502	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	782	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
503	the path C<$dstpath> and call the callback with the result code.	783	the path C<$dstpath> and call the callback with the result code.
504		784
505		785
506	=item aio_readlink $path, $callback->($link)	786	=item aio_readlink $pathname, $callback->($link)
507		787
508	Asynchronously read the symlink specified by C<$path> and pass it to	788	Asynchronously read the symlink specified by C<$path> and pass it to
509	the callback. If an error occurs, nothing or undef gets passed to the	789	the callback. If an error occurs, nothing or undef gets passed to the
510	callback.	790	callback.
511		791
512		792
		793	=item aio_realpath $pathname, $callback->($path)
		794
		795	Asynchronously make the path absolute and resolve any symlinks in
		796	C<$path>. The resulting path only consists of directories (same as
		797	L<Cwd::realpath>).
		798
		799	This request can be used to get the absolute path of the current working
		800	directory by passing it a path of F<.> (a single dot).
		801
		802
513	=item aio_rename $srcpath, $dstpath, $callback->($status)	803	=item aio_rename $srcpath, $dstpath, $callback->($status)
514		804
515	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	805	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
516	rename(2) and call the callback with the result code.	806	rename(2) and call the callback with the result code.
		807
		808	On systems that support the AIO::WD working directory abstraction
		809	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		810	of failing, C<rename> is called on the absolute path of C<$wd>.
517		811
518		812
519	=item aio_mkdir $pathname, $mode, $callback->($status)	813	=item aio_mkdir $pathname, $mode, $callback->($status)
520		814
521	Asynchronously mkdir (create) a directory and call the callback with	815	Asynchronously mkdir (create) a directory and call the callback with
…		…
526	=item aio_rmdir $pathname, $callback->($status)	820	=item aio_rmdir $pathname, $callback->($status)
527		821
528	Asynchronously rmdir (delete) a directory and call the callback with the	822	Asynchronously rmdir (delete) a directory and call the callback with the
529	result code.	823	result code.
530		824
		825	On systems that support the AIO::WD working directory abstraction
		826	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		827	C<rmdir> is called on the absolute path of C<$wd>.
		828
531		829
532	=item aio_readdir $pathname, $callback->($entries)	830	=item aio_readdir $pathname, $callback->($entries)
533		831
534	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	832	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
535	directory (i.e. opendir + readdir + closedir). The entries will not be	833	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
539	array-ref with the filenames.	837	array-ref with the filenames.
540		838
541		839
542	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	840	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
543		841
544	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	842	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
545	behaviour and output format. In case of an error, C<$entries> will be	843	tune behaviour and output format. In case of an error, C<$entries> will be
546	C<undef>.	844	C<undef>.
547		845
548	The flags are a combination of the following constants, ORed together (the	846	The flags are a combination of the following constants, ORed together (the
549	flags will also be passed to the callback, possibly modified):	847	flags will also be passed to the callback, possibly modified):
550		848
551	=over 4	849	=over 4
552		850
553	=item IO::AIO::READDIR_DENTS	851	=item IO::AIO::READDIR_DENTS
554		852
555	When this flag is off, then the callback gets an arrayref with of names	853	When this flag is off, then the callback gets an arrayref consisting of
556	only (as with C<aio_readdir>), otherwise it gets an arrayref with	854	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
557	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	855	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
558	entry in more detail.	856	entry in more detail.
559		857
560	C<$name> is the name of the entry.	858	C<$name> is the name of the entry.
561		859
…		…
568	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	866	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
569	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	867	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
570	scalars are read-only: you can not modify them.	868	scalars are read-only: you can not modify them.
571		869
572	C<$inode> is the inode number (which might not be exact on systems with 64	870	C<$inode> is the inode number (which might not be exact on systems with 64
573	bit inode numbers and 32 bit perls). On systems that do not deliver the	871	bit inode numbers and 32 bit perls). This field has unspecified content on
574	inode information, this will always be zero.	872	systems that do not deliver the inode information.
575		873
576	=item IO::AIO::READDIR_DIRS_FIRST	874	=item IO::AIO::READDIR_DIRS_FIRST
577		875
578	When this flag is set, then the names will be returned in an order where	876	When this flag is set, then the names will be returned in an order where
579	likely directories come first. This is useful when you need to quickly	877	likely directories come first, in optimal stat order. This is useful when
580	find directories, or you want to find all directories while avoiding to	878	you need to quickly find directories, or you want to find all directories
581	stat() each entry.	879	while avoiding to stat() each entry.
582		880
583	If the system returns type information in readdir, then this is used	881	If the system returns type information in readdir, then this is used
584	to find directories directly. Otherwise, likely directories are files	882	to find directories directly. Otherwise, likely directories are names
585	beginning with ".", or otherwise files with no dots, of which files with	883	beginning with ".", or otherwise names with no dots, of which names with
586	short names are tried first.	884	short names are tried first.
587		885
588	=item IO::AIO::READDIR_STAT_ORDER	886	=item IO::AIO::READDIR_STAT_ORDER
589		887
590	When this flag is set, then the names will be returned in an order	888	When this flag is set, then the names will be returned in an order
…		…
597		895
598	=item IO::AIO::READDIR_FOUND_UNKNOWN	896	=item IO::AIO::READDIR_FOUND_UNKNOWN
599		897
600	This flag should not be set when calling C<aio_readdirx>. Instead, it	898	This flag should not be set when calling C<aio_readdirx>. Instead, it
601	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	899	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
602	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	900	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
603	C<$type>'s are known, which can be used to speed up some algorithms.	901	C<$type>'s are known, which can be used to speed up some algorithms.
604		902
605	=back	903	=back
606		904
607		905
608	=item aio_load $path, $data, $callback->($status)	906	=item aio_load $pathname, $data, $callback->($status)
609		907
610	This is a composite request that tries to fully load the given file into	908	This is a composite request that tries to fully load the given file into
611	memory. Status is the same as with aio_read.	909	memory. Status is the same as with aio_read.
612		910
613	=cut	911	=cut
…		…
635		933
636	=item aio_copy $srcpath, $dstpath, $callback->($status)	934	=item aio_copy $srcpath, $dstpath, $callback->($status)
637		935
638	Try to copy the I<file> (directories not supported as either source or	936	Try to copy the I<file> (directories not supported as either source or
639	destination) from C<$srcpath> to C<$dstpath> and call the callback with	937	destination) from C<$srcpath> to C<$dstpath> and call the callback with
640	the C<0> (error) or C<-1> ok.	938	a status of C<0> (ok) or C<-1> (error, see C<$!>).
641		939
642	This is a composite request that creates the destination file with	940	This is a composite request that creates the destination file with
643	mode 0200 and copies the contents of the source file into it using	941	mode 0200 and copies the contents of the source file into it using
644	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	942	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
645	uid/gid, in that order.	943	uid/gid, in that order.
…		…
657	my $grp = aio_group $cb;	955	my $grp = aio_group $cb;
658		956
659	aioreq_pri $pri;	957	aioreq_pri $pri;
660	add $grp aio_open $src, O_RDONLY, 0, sub {	958	add $grp aio_open $src, O_RDONLY, 0, sub {
661	if (my $src_fh = $_[0]) {	959	if (my $src_fh = $_[0]) {
662	my @stat = stat $src_fh; # hmm, might bock over nfs?	960	my @stat = stat $src_fh; # hmm, might block over nfs?
663		961
664	aioreq_pri $pri;	962	aioreq_pri $pri;
665	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	963	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
666	if (my $dst_fh = $_[0]) {	964	if (my $dst_fh = $_[0]) {
667	aioreq_pri $pri;	965	aioreq_pri $pri;
…		…
714		1012
715	=item aio_move $srcpath, $dstpath, $callback->($status)	1013	=item aio_move $srcpath, $dstpath, $callback->($status)
716		1014
717	Try to move the I<file> (directories not supported as either source or	1015	Try to move the I<file> (directories not supported as either source or
718	destination) from C<$srcpath> to C<$dstpath> and call the callback with	1016	destination) from C<$srcpath> to C<$dstpath> and call the callback with
719	the C<0> (error) or C<-1> ok.	1017	a status of C<0> (ok) or C<-1> (error, see C<$!>).
720		1018
721	This is a composite request that tries to rename(2) the file first; if	1019	This is a composite request that tries to rename(2) the file first; if
722	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	1020	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
723	that is successful, unlinks the C<$srcpath>.	1021	that is successful, unlinks the C<$srcpath>.
724		1022
…		…
735	if ($_[0] && $! == EXDEV) {	1033	if ($_[0] && $! == EXDEV) {
736	aioreq_pri $pri;	1034	aioreq_pri $pri;
737	add $grp aio_copy $src, $dst, sub {	1035	add $grp aio_copy $src, $dst, sub {
738	$grp->result ($_[0]);	1036	$grp->result ($_[0]);
739		1037
740	if (!$_[0]) {	1038	unless ($_[0]) {
741	aioreq_pri $pri;	1039	aioreq_pri $pri;
742	add $grp aio_unlink $src;	1040	add $grp aio_unlink $src;
743	}	1041	}
744	};	1042	};
745	} else {	1043	} else {
…		…
748	};	1046	};
749		1047
750	$grp	1048	$grp
751	}	1049	}
752		1050
753	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1051	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
754		1052
755	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1053	Scans a directory (similar to C<aio_readdir>) but additionally tries to
756	efficiently separate the entries of directory C<$path> into two sets of	1054	efficiently separate the entries of directory C<$path> into two sets of
757	names, directories you can recurse into (directories), and ones you cannot	1055	names, directories you can recurse into (directories), and ones you cannot
758	recurse into (everything else, including symlinks to directories).	1056	recurse into (everything else, including symlinks to directories).
…		…
789	Then entries will be sorted into likely directories a non-initial dot	1087	Then entries will be sorted into likely directories a non-initial dot
790	currently) and likely non-directories (see C<aio_readdirx>). Then every	1088	currently) and likely non-directories (see C<aio_readdirx>). Then every
791	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1089	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
792	in order of their inode numbers. If that succeeds, it assumes that the	1090	in order of their inode numbers. If that succeeds, it assumes that the
793	entry is a directory or a symlink to directory (which will be checked	1091	entry is a directory or a symlink to directory (which will be checked
794	seperately). This is often faster than stat'ing the entry itself because	1092	separately). This is often faster than stat'ing the entry itself because
795	filesystems might detect the type of the entry without reading the inode	1093	filesystems might detect the type of the entry without reading the inode
796	data (e.g. ext2fs filetype feature), even on systems that cannot return	1094	data (e.g. ext2fs filetype feature), even on systems that cannot return
797	the filetype information on readdir.	1095	the filetype information on readdir.
798		1096
799	If the known number of directories (link count - 2) has been reached, the	1097	If the known number of directories (link count - 2) has been reached, the
…		…
815		1113
816	my $grp = aio_group $cb;	1114	my $grp = aio_group $cb;
817		1115
818	$maxreq = 4 if $maxreq <= 0;	1116	$maxreq = 4 if $maxreq <= 0;
819		1117
820	# stat once	1118	# get a wd object
821	aioreq_pri $pri;	1119	aioreq_pri $pri;
822	add $grp aio_stat $path, sub {	1120	add $grp aio_wd $path, sub {
		1121	$_[0]
823	return $grp->result () if $_[0];	1122	or return $grp->result ();
824	my $now = time;
825	my $hash1 = join ":", (stat _)[0,1,3,7,9];
826		1123
827	# read the directory entries	1124	my $wd = [shift, "."];
		1125
		1126	# stat once
828	aioreq_pri $pri;	1127	aioreq_pri $pri;
829	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1128	add $grp aio_stat $wd, sub {
830	my $entries = shift
831	or return $grp->result ();	1129	return $grp->result () if $_[0];
		1130	my $now = time;
		1131	my $hash1 = join ":", (stat _)[0,1,3,7,9];
832		1132
833	# stat the dir another time	1133	# read the directory entries
834	aioreq_pri $pri;	1134	aioreq_pri $pri;
		1135	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1136	my $entries = shift
		1137	or return $grp->result ();
		1138
		1139	# stat the dir another time
		1140	aioreq_pri $pri;
835	add $grp aio_stat $path, sub {	1141	add $grp aio_stat $wd, sub {
836	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1142	my $hash2 = join ":", (stat _)[0,1,3,7,9];
837		1143
838	my $ndirs;	1144	my $ndirs;
839		1145
840	# take the slow route if anything looks fishy	1146	# take the slow route if anything looks fishy
841	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1147	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
842	$ndirs = -1;	1148	$ndirs = -1;
843	} else {	1149	} else {
844	# if nlink == 2, we are finished	1150	# if nlink == 2, we are finished
845	# for non-posix-fs's, we rely on nlink < 2	1151	# for non-posix-fs's, we rely on nlink < 2
846	$ndirs = (stat _)[3] - 2	1152	$ndirs = (stat _)[3] - 2
847	or return $grp->result ([], $entries);	1153	or return $grp->result ([], $entries);
848	}	1154	}
849		1155
850	my (@dirs, @nondirs);	1156	my (@dirs, @nondirs);
851		1157
852	my $statgrp = add $grp aio_group sub {	1158	my $statgrp = add $grp aio_group sub {
853	$grp->result (\@dirs, \@nondirs);	1159	$grp->result (\@dirs, \@nondirs);
854	};	1160	};
855		1161
856	limit $statgrp $maxreq;	1162	limit $statgrp $maxreq;
857	feed $statgrp sub {	1163	feed $statgrp sub {
858	return unless @$entries;	1164	return unless @$entries;
859	my $entry = shift @$entries;	1165	my $entry = shift @$entries;
860		1166
861	aioreq_pri $pri;	1167	aioreq_pri $pri;
		1168	$wd->[1] = "$entry/.";
862	add $statgrp aio_stat "$path/$entry/.", sub {	1169	add $statgrp aio_stat $wd, sub {
863	if ($_[0] < 0) {	1170	if ($_[0] < 0) {
864	push @nondirs, $entry;	1171	push @nondirs, $entry;
865	} else {	1172	} else {
866	# need to check for real directory	1173	# need to check for real directory
867	aioreq_pri $pri;	1174	aioreq_pri $pri;
		1175	$wd->[1] = $entry;
868	add $statgrp aio_lstat "$path/$entry", sub {	1176	add $statgrp aio_lstat $wd, sub {
869	if (-d _) {	1177	if (-d _) {
870	push @dirs, $entry;	1178	push @dirs, $entry;
871		1179
872	unless (--$ndirs) {	1180	unless (--$ndirs) {
873	push @nondirs, @$entries;	1181	push @nondirs, @$entries;
874	feed $statgrp;	1182	feed $statgrp;
		1183	}
		1184	} else {
		1185	push @nondirs, $entry;
875	}	1186	}
876	} else {
877	push @nondirs, $entry;
878	}	1187	}
879	}	1188	}
880	}	1189	};
881	};	1190	};
882	};	1191	};
883	};	1192	};
884	};	1193	};
885	};	1194	};
886		1195
887	$grp	1196	$grp
888	}	1197	}
889		1198
890	=item aio_rmtree $path, $callback->($status)	1199	=item aio_rmtree $pathname, $callback->($status)
891		1200
892	Delete a directory tree starting (and including) C<$path>, return the	1201	Delete a directory tree starting (and including) C<$path>, return the
893	status of the final C<rmdir> only. This is a composite request that	1202	status of the final C<rmdir> only. This is a composite request that
894	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1203	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
895	everything else.	1204	everything else.
896		1205
897	=cut	1206	=cut
898		1207
…		…
920	};	1229	};
921		1230
922	$grp	1231	$grp
923	}	1232	}
924		1233
		1234	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1235
		1236	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1237
		1238	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1239	they execute asynchronously and pass the return value to the callback.
		1240
		1241	Both calls can be used for a lot of things, some of which make more sense
		1242	to run asynchronously in their own thread, while some others make less
		1243	sense. For example, calls that block waiting for external events, such
		1244	as locking, will also lock down an I/O thread while it is waiting, which
		1245	can deadlock the whole I/O system. At the same time, there might be no
		1246	alternative to using a thread to wait.
		1247
		1248	So in general, you should only use these calls for things that do
		1249	(filesystem) I/O, not for things that wait for other events (network,
		1250	other processes), although if you are careful and know what you are doing,
		1251	you still can.
		1252
		1253	The following constants are available (missing ones are, as usual C<0>):
		1254
		1255	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1256
		1257	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1258	C<FS_IOC_FIEMAP>.
		1259
		1260	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1261	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1262
		1263	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1264	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1265	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1266	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1267	C<FS_FL_USER_MODIFIABLE>.
		1268
		1269	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1270	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1271	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1272	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1273
925	=item aio_sync $callback->($status)	1274	=item aio_sync $callback->($status)
926		1275
927	Asynchronously call sync and call the callback when finished.	1276	Asynchronously call sync and call the callback when finished.
928		1277
929	=item aio_fsync $fh, $callback->($status)	1278	=item aio_fsync $fh, $callback->($status)
…		…
936	Asynchronously call fdatasync on the given filehandle and call the	1285	Asynchronously call fdatasync on the given filehandle and call the
937	callback with the fdatasync result code.	1286	callback with the fdatasync result code.
938		1287
939	If this call isn't available because your OS lacks it or it couldn't be	1288	If this call isn't available because your OS lacks it or it couldn't be
940	detected, it will be emulated by calling C<fsync> instead.	1289	detected, it will be emulated by calling C<fsync> instead.
		1290
		1291	=item aio_syncfs $fh, $callback->($status)
		1292
		1293	Asynchronously call the syncfs syscall to sync the filesystem associated
		1294	to the given filehandle and call the callback with the syncfs result
		1295	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1296	errno to C<ENOSYS> nevertheless.
941		1297
942	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1298	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
943		1299
944	Sync the data portion of the file specified by C<$offset> and C<$length>	1300	Sync the data portion of the file specified by C<$offset> and C<$length>
945	to disk (but NOT the metadata), by calling the Linux-specific	1301	to disk (but NOT the metadata), by calling the Linux-specific
…		…
949	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1305	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
950	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1306	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
951	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1307	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
952	manpage for details.	1308	manpage for details.
953		1309
954	=item aio_pathsync $path, $callback->($status)	1310	=item aio_pathsync $pathname, $callback->($status)
955		1311
956	This request tries to open, fsync and close the given path. This is a	1312	This request tries to open, fsync and close the given path. This is a
957	composite request intended to sync directories after directory operations	1313	composite request intended to sync directories after directory operations
958	(E.g. rename). This might not work on all operating systems or have any	1314	(E.g. rename). This might not work on all operating systems or have any
959	specific effect, but usually it makes sure that directory changes get	1315	specific effect, but usually it makes sure that directory changes get
960	written to disc. It works for anything that can be opened for read-only,	1316	written to disc. It works for anything that can be opened for read-only,
961	not just directories.	1317	not just directories.
		1318
		1319	Future versions of this function might fall back to other methods when
		1320	C<fsync> on the directory fails (such as calling C<sync>).
962		1321
963	Passes C<0> when everything went ok, and C<-1> on error.	1322	Passes C<0> when everything went ok, and C<-1> on error.
964		1323
965	=cut	1324	=cut
966		1325
…		…
987	};	1346	};
988		1347
989	$grp	1348	$grp
990	}	1349	}
991		1350
		1351	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1352
		1353	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1354	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1355	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1356	scalar must only be modified in-place while an aio operation is pending on
		1357	it).
		1358
		1359	It calls the C<msync> function of your OS, if available, with the memory
		1360	area starting at C<$offset> in the string and ending C<$length> bytes
		1361	later. If C<$length> is negative, counts from the end, and if C<$length>
		1362	is C<undef>, then it goes till the end of the string. The flags can be
		1363	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1364	C<IO::AIO::MS_SYNC>.
		1365
		1366	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1367
		1368	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1369	scalars.
		1370
		1371	It touches (reads or writes) all memory pages in the specified
		1372	range inside the scalar. All caveats and parameters are the same
		1373	as for C<aio_msync>, above, except for flags, which must be either
		1374	C<0> (which reads all pages and ensures they are instantiated) or
		1375	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
		1376	writing an octet from it, which dirties the page).
		1377
		1378	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1379
		1380	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1381	scalars.
		1382
		1383	It reads in all the pages of the underlying storage into memory (if any)
		1384	and locks them, so they are not getting swapped/paged out or removed.
		1385
		1386	If C<$length> is undefined, then the scalar will be locked till the end.
		1387
		1388	On systems that do not implement C<mlock>, this function returns C<-1>
		1389	and sets errno to C<ENOSYS>.
		1390
		1391	Note that the corresponding C<munlock> is synchronous and is
		1392	documented under L<MISCELLANEOUS FUNCTIONS>.
		1393
		1394	Example: open a file, mmap and mlock it - both will be undone when
		1395	C<$data> gets destroyed.
		1396
		1397	open my $fh, "<", $path or die "$path: $!";
		1398	my $data;
		1399	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1400	aio_mlock $data; # mlock in background
		1401
		1402	=item aio_mlockall $flags, $callback->($status)
		1403
		1404	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1405	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1406
		1407	On systems that do not implement C<mlockall>, this function returns C<-1>
		1408	and sets errno to C<ENOSYS>.
		1409
		1410	Note that the corresponding C<munlockall> is synchronous and is
		1411	documented under L<MISCELLANEOUS FUNCTIONS>.
		1412
		1413	Example: asynchronously lock all current and future pages into memory.
		1414
		1415	aio_mlockall IO::AIO::MCL_FUTURE;
		1416
		1417	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1418
		1419	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1420	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1421	the ioctl is not available on your OS, then this request will fail with
		1422	C<ENOSYS>.
		1423
		1424	C<$start> is the starting offset to query extents for, C<$length> is the
		1425	size of the range to query - if it is C<undef>, then the whole file will
		1426	be queried.
		1427
		1428	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1429	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1430	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1431	the data portion.
		1432
		1433	C<$count> is the maximum number of extent records to return. If it is
		1434	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1435	case, if it is C<0>, then the callback receives the number of extents
		1436	instead of the extents themselves (which is unreliable, see below).
		1437
		1438	If an error occurs, the callback receives no arguments. The special
		1439	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1440
		1441	Otherwise, the callback receives an array reference with extent
		1442	structures. Each extent structure is an array reference itself, with the
		1443	following members:
		1444
		1445	[$logical, $physical, $length, $flags]
		1446
		1447	Flags is any combination of the following flag values (typically either C<0>
		1448	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1449
		1450	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1451	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1452	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1453	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1454	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1455	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1456
		1457	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1458	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1459	it to return all extents of a range for files with large number of
		1460	extents. The code works around all these issues if C<$count> is undef.
		1461
992	=item aio_group $callback->(...)	1462	=item aio_group $callback->(...)
993		1463
994	This is a very special aio request: Instead of doing something, it is a	1464	This is a very special aio request: Instead of doing something, it is a
995	container for other aio requests, which is useful if you want to bundle	1465	container for other aio requests, which is useful if you want to bundle
996	many requests into a single, composite, request with a definite callback	1466	many requests into a single, composite, request with a definite callback
…		…
1032	like sleep and file handle readable/writable, the overhead this creates is	1502	like sleep and file handle readable/writable, the overhead this creates is
1033	immense (it blocks a thread for a long time) so do not use this function	1503	immense (it blocks a thread for a long time) so do not use this function
1034	except to put your application under artificial I/O pressure.	1504	except to put your application under artificial I/O pressure.
1035		1505
1036	=back	1506	=back
		1507
		1508
		1509	=head2 IO::AIO::WD - multiple working directories
		1510
		1511	Your process only has one current working directory, which is used by all
		1512	threads. This makes it hard to use relative paths (some other component
		1513	could call C<chdir> at any time, and it is hard to control when the path
		1514	will be used by IO::AIO).
		1515
		1516	One solution for this is to always use absolute paths. This usually works,
		1517	but can be quite slow (the kernel has to walk the whole path on every
		1518	access), and can also be a hassle to implement.
		1519
		1520	Newer POSIX systems have a number of functions (openat, fdopendir,
		1521	futimensat and so on) that make it possible to specify working directories
		1522	per operation.
		1523
		1524	For portability, and because the clowns who "designed", or shall I write,
		1525	perpetrated this new interface were obviously half-drunk, this abstraction
		1526	cannot be perfect, though.
		1527
		1528	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1529	object. This object stores the canonicalised, absolute version of the
		1530	path, and on systems that allow it, also a directory file descriptor.
		1531
		1532	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1533	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1534	object and a pathname instead (or the IO::AIO::WD object alone, which
		1535	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1536	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1537	to that IO::AIO::WD object.
		1538
		1539	For example, to get a wd object for F</etc> and then stat F<passwd>
		1540	inside, you would write:
		1541
		1542	aio_wd "/etc", sub {
		1543	my $etcdir = shift;
		1544
		1545	# although $etcdir can be undef on error, there is generally no reason
		1546	# to check for errors here, as aio_stat will fail with ENOENT
		1547	# when $etcdir is undef.
		1548
		1549	aio_stat [$etcdir, "passwd"], sub {
		1550	# yay
		1551	};
		1552	};
		1553
		1554	The fact that C<aio_wd> is a request and not a normal function shows that
		1555	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1556	which is why it is done asynchronously.
		1557
		1558	To stat the directory obtained with C<aio_wd> above, one could write
		1559	either of the following three request calls:
		1560
		1561	aio_lstat "/etc" , sub { ... # pathname as normal string
		1562	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1563	aio_lstat $wd , sub { ... # shorthand for the previous
		1564
		1565	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1566	object and the pathname string, so you could write the following without
		1567	causing any issues due to C<$path> getting reused:
		1568
		1569	my $path = [$wd, undef];
		1570
		1571	for my $name (qw(abc def ghi)) {
		1572	$path->[1] = $name;
		1573	aio_stat $path, sub {
		1574	# ...
		1575	};
		1576	}
		1577
		1578	There are some caveats: when directories get renamed (or deleted), the
		1579	pathname string doesn't change, so will point to the new directory (or
		1580	nowhere at all), while the directory fd, if available on the system,
		1581	will still point to the original directory. Most functions accepting a
		1582	pathname will use the directory fd on newer systems, and the string on
		1583	older systems. Some functions (such as realpath) will always rely on the
		1584	string form of the pathname.
		1585
		1586	So this functionality is mainly useful to get some protection against
		1587	C<chdir>, to easily get an absolute path out of a relative path for future
		1588	reference, and to speed up doing many operations in the same directory
		1589	(e.g. when stat'ing all files in a directory).
		1590
		1591	The following functions implement this working directory abstraction:
		1592
		1593	=over 4
		1594
		1595	=item aio_wd $pathname, $callback->($wd)
		1596
		1597	Asynchonously canonicalise the given pathname and convert it to an
		1598	IO::AIO::WD object representing it. If possible and supported on the
		1599	system, also open a directory fd to speed up pathname resolution relative
		1600	to this working directory.
		1601
		1602	If something goes wrong, then C<undef> is passwd to the callback instead
		1603	of a working directory object and C<$!> is set appropriately. Since
		1604	passing C<undef> as working directory component of a pathname fails the
		1605	request with C<ENOENT>, there is often no need for error checking in the
		1606	C<aio_wd> callback, as future requests using the value will fail in the
		1607	expected way.
		1608
		1609	=item IO::AIO::CWD
		1610
		1611	This is a compiletime constant (object) that represents the process
		1612	current working directory.
		1613
		1614	Specifying this object as working directory object for a pathname is as if
		1615	the pathname would be specified directly, without a directory object. For
		1616	example, these calls are functionally identical:
		1617
		1618	aio_stat "somefile", sub { ... };
		1619	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1620
		1621	=back
		1622
		1623	To recover the path associated with an IO::AIO::WD object, you can use
		1624	C<aio_realpath>:
		1625
		1626	aio_realpath $wd, sub {
		1627	warn "path is $_[0]\n";
		1628	};
		1629
		1630	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1631	sometimes, fall back to using an absolue path.
1037		1632
1038	=head2 IO::AIO::REQ CLASS	1633	=head2 IO::AIO::REQ CLASS
1039		1634
1040	All non-aggregate C<aio_*> functions return an object of this class when	1635	All non-aggregate C<aio_*> functions return an object of this class when
1041	called in non-void context.	1636	called in non-void context.
…		…
1131	=item $grp->cancel_subs	1726	=item $grp->cancel_subs
1132		1727
1133	Cancel all subrequests and clears any feeder, but not the group request	1728	Cancel all subrequests and clears any feeder, but not the group request
1134	itself. Useful when you queued a lot of events but got a result early.	1729	itself. Useful when you queued a lot of events but got a result early.
1135		1730
		1731	The group request will finish normally (you cannot add requests to the
		1732	group).
		1733
1136	=item $grp->result (...)	1734	=item $grp->result (...)
1137		1735
1138	Set the result value(s) that will be passed to the group callback when all	1736	Set the result value(s) that will be passed to the group callback when all
1139	subrequests have finished and set the groups errno to the current value	1737	subrequests have finished and set the groups errno to the current value
1140	of errno (just like calling C<errno> without an error number). By default,	1738	of errno (just like calling C<errno> without an error number). By default,
…		…
1156		1754
1157	Sets a feeder/generator on this group: every group can have an attached	1755	Sets a feeder/generator on this group: every group can have an attached
1158	generator that generates requests if idle. The idea behind this is that,	1756	generator that generates requests if idle. The idea behind this is that,
1159	although you could just queue as many requests as you want in a group,	1757	although you could just queue as many requests as you want in a group,
1160	this might starve other requests for a potentially long time. For example,	1758	this might starve other requests for a potentially long time. For example,
1161	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1759	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1162	delaying any later requests for a long time.	1760	requests, delaying any later requests for a long time.
1163		1761
1164	To avoid this, and allow incremental generation of requests, you can	1762	To avoid this, and allow incremental generation of requests, you can
1165	instead a group and set a feeder on it that generates those requests. The	1763	instead a group and set a feeder on it that generates those requests. The
1166	feed callback will be called whenever there are few enough (see C<limit>,	1764	feed callback will be called whenever there are few enough (see C<limit>,
1167	below) requests active in the group itself and is expected to queue more	1765	below) requests active in the group itself and is expected to queue more
…		…
1208	=over 4	1806	=over 4
1209		1807
1210	=item $fileno = IO::AIO::poll_fileno	1808	=item $fileno = IO::AIO::poll_fileno
1211		1809
1212	Return the I<request result pipe file descriptor>. This filehandle must be	1810	Return the I<request result pipe file descriptor>. This filehandle must be
1213	polled for reading by some mechanism outside this module (e.g. Event or	1811	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1214	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1812	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1215	to call C<poll_cb> to check the results.	1813	you have to call C<poll_cb> to check the results.
1216		1814
1217	See C<poll_cb> for an example.	1815	See C<poll_cb> for an example.
1218		1816
1219	=item IO::AIO::poll_cb	1817	=item IO::AIO::poll_cb
1220		1818
1221	Process some outstanding events on the result pipe. You have to call this	1819	Process some requests that have reached the result phase (i.e. they have
1222	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1820	been executed but the results are not yet reported). You have to call
1223	returned earlier for whatever reason. Returns immediately when no events	1821	this "regularly" to finish outstanding requests.
1224	are outstanding. The amount of events processed depends on the settings of
1225	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1226		1822
		1823	Returns C<0> if all events could be processed (or there were no
		1824	events to process), or C<-1> if it returned earlier for whatever
		1825	reason. Returns immediately when no events are outstanding. The amount
		1826	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1827	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1828
1227	If not all requests were processed for whatever reason, the filehandle	1829	If not all requests were processed for whatever reason, the poll file
1228	will still be ready when C<poll_cb> returns, so normally you don't have to	1830	descriptor will still be ready when C<poll_cb> returns, so normally you
1229	do anything special to have it called later.	1831	don't have to do anything special to have it called later.
		1832
		1833	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1834	ready, it can be beneficial to call this function from loops which submit
		1835	a lot of requests, to make sure the results get processed when they become
		1836	available and not just when the loop is finished and the event loop takes
		1837	over again. This function returns very fast when there are no outstanding
		1838	requests.
1230		1839
1231	Example: Install an Event watcher that automatically calls	1840	Example: Install an Event watcher that automatically calls
1232	IO::AIO::poll_cb with high priority:	1841	IO::AIO::poll_cb with high priority (more examples can be found in the
		1842	SYNOPSIS section, at the top of this document):
1233		1843
1234	Event->io (fd => IO::AIO::poll_fileno,	1844	Event->io (fd => IO::AIO::poll_fileno,
1235	poll => 'r', async => 1,	1845	poll => 'r', async => 1,
1236	cb => \&IO::AIO::poll_cb);	1846	cb => \&IO::AIO::poll_cb);
		1847
		1848	=item IO::AIO::poll_wait
		1849
		1850	Wait until either at least one request is in the result phase or no
		1851	requests are outstanding anymore.
		1852
		1853	This is useful if you want to synchronously wait for some requests to
		1854	become ready, without actually handling them.
		1855
		1856	See C<nreqs> for an example.
		1857
		1858	=item IO::AIO::poll
		1859
		1860	Waits until some requests have been handled.
		1861
		1862	Returns the number of requests processed, but is otherwise strictly
		1863	equivalent to:
		1864
		1865	IO::AIO::poll_wait, IO::AIO::poll_cb
		1866
		1867	=item IO::AIO::flush
		1868
		1869	Wait till all outstanding AIO requests have been handled.
		1870
		1871	Strictly equivalent to:
		1872
		1873	IO::AIO::poll_wait, IO::AIO::poll_cb
		1874	while IO::AIO::nreqs;
1237		1875
1238	=item IO::AIO::max_poll_reqs $nreqs	1876	=item IO::AIO::max_poll_reqs $nreqs
1239		1877
1240	=item IO::AIO::max_poll_time $seconds	1878	=item IO::AIO::max_poll_time $seconds
1241		1879
…		…
1266	# use a low priority so other tasks have priority	1904	# use a low priority so other tasks have priority
1267	Event->io (fd => IO::AIO::poll_fileno,	1905	Event->io (fd => IO::AIO::poll_fileno,
1268	poll => 'r', nice => 1,	1906	poll => 'r', nice => 1,
1269	cb => &IO::AIO::poll_cb);	1907	cb => &IO::AIO::poll_cb);
1270		1908
1271	=item IO::AIO::poll_wait
1272
1273	If there are any outstanding requests and none of them in the result
1274	phase, wait till the result filehandle becomes ready for reading (simply
1275	does a C<select> on the filehandle. This is useful if you want to
1276	synchronously wait for some requests to finish).
1277
1278	See C<nreqs> for an example.
1279
1280	=item IO::AIO::poll
1281
1282	Waits until some requests have been handled.
1283
1284	Returns the number of requests processed, but is otherwise strictly
1285	equivalent to:
1286
1287	IO::AIO::poll_wait, IO::AIO::poll_cb
1288
1289	=item IO::AIO::flush
1290
1291	Wait till all outstanding AIO requests have been handled.
1292
1293	Strictly equivalent to:
1294
1295	IO::AIO::poll_wait, IO::AIO::poll_cb
1296	while IO::AIO::nreqs;
1297
1298	=back	1909	=back
1299		1910
1300	=head3 CONTROLLING THE NUMBER OF THREADS	1911	=head3 CONTROLLING THE NUMBER OF THREADS
1301		1912
1302	=over	1913	=over
…		…
1335		1946
1336	Under normal circumstances you don't need to call this function.	1947	Under normal circumstances you don't need to call this function.
1337		1948
1338	=item IO::AIO::max_idle $nthreads	1949	=item IO::AIO::max_idle $nthreads
1339		1950
1340	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1951	Limit the number of threads (default: 4) that are allowed to idle
1341	threads that did not get a request to process within 10 seconds). That	1952	(i.e., threads that did not get a request to process within the idle
1342	means if a thread becomes idle while C<$nthreads> other threads are also	1953	timeout (default: 10 seconds). That means if a thread becomes idle while
1343	idle, it will free its resources and exit.	1954	C<$nthreads> other threads are also idle, it will free its resources and
		1955	exit.
1344		1956
1345	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1957	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1346	to allow for extremely high load situations, but want to free resources	1958	to allow for extremely high load situations, but want to free resources
1347	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1959	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348		1960
1349	The default is probably ok in most situations, especially if thread	1961	The default is probably ok in most situations, especially if thread
1350	creation is fast. If thread creation is very slow on your system you might	1962	creation is fast. If thread creation is very slow on your system you might
1351	want to use larger values.	1963	want to use larger values.
1352		1964
		1965	=item IO::AIO::idle_timeout $seconds
		1966
		1967	Sets the minimum idle timeout (default 10) after which worker threads are
		1968	allowed to exit. SEe C<IO::AIO::max_idle>.
		1969
1353	=item IO::AIO::max_outstanding $maxreqs	1970	=item IO::AIO::max_outstanding $maxreqs
		1971
		1972	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1973	you do queue up more than this number of requests, the next call to
		1974	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1975	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1976	longer exceeded.
		1977
		1978	In other words, this setting does not enforce a queue limit, but can be
		1979	used to make poll functions block if the limit is exceeded.
1354		1980
1355	This is a very bad function to use in interactive programs because it	1981	This is a very bad function to use in interactive programs because it
1356	blocks, and a bad way to reduce concurrency because it is inexact: Better	1982	blocks, and a bad way to reduce concurrency because it is inexact: Better
1357	use an C<aio_group> together with a feed callback.	1983	use an C<aio_group> together with a feed callback.
1358		1984
1359	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1985	Its main use is in scripts without an event loop - when you want to stat
1360	do queue up more than this number of requests, the next call to the	1986	a lot of files, you can write somehting like this:
1361	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1362	function will block until the limit is no longer exceeded.
1363		1987
1364	The default value is very large, so there is no practical limit on the	1988	IO::AIO::max_outstanding 32;
1365	number of outstanding requests.
1366		1989
1367	You can still queue as many requests as you want. Therefore,	1990	for my $path (...) {
1368	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1991	aio_stat $path , ...;
1369	as a stop gap to shield against fatal memory overflow (with large values).	1992	IO::AIO::poll_cb;
		1993	}
		1994
		1995	IO::AIO::flush;
		1996
		1997	The call to C<poll_cb> inside the loop will normally return instantly, but
		1998	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1999	some requests have been handled. This keeps the loop from pushing a large
		2000	number of C<aio_stat> requests onto the queue.
		2001
		2002	The default value for C<max_outstanding> is very large, so there is no
		2003	practical limit on the number of outstanding requests.
1370		2004
1371	=back	2005	=back
1372		2006
1373	=head3 STATISTICAL INFORMATION	2007	=head3 STATISTICAL INFORMATION
1374		2008
…		…
1394	Returns the number of requests currently in the pending state (executed,	2028	Returns the number of requests currently in the pending state (executed,
1395	but not yet processed by poll_cb).	2029	but not yet processed by poll_cb).
1396		2030
1397	=back	2031	=back
1398		2032
		2033	=head3 MISCELLANEOUS FUNCTIONS
		2034
		2035	IO::AIO implements some functions that are useful when you want to use
		2036	some "Advanced I/O" function not available to in Perl, without going the
		2037	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2038	counterpart.
		2039
		2040	=over 4
		2041
		2042	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		2043
		2044	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		2045	but is blocking (this makes most sense if you know the input data is
		2046	likely cached already and the output filehandle is set to non-blocking
		2047	operations).
		2048
		2049	Returns the number of bytes copied, or C<-1> on error.
		2050
		2051	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		2052
		2053	Simply calls the C<posix_fadvise> function (see its
		2054	manpage for details). The following advice constants are
		2055	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		2056	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		2057	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		2058
		2059	On systems that do not implement C<posix_fadvise>, this function returns
		2060	ENOSYS, otherwise the return value of C<posix_fadvise>.
		2061
		2062	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2063
		2064	Simply calls the C<posix_madvise> function (see its
		2065	manpage for details). The following advice constants are
		2066	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2067	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
		2068	C<IO::AIO::MADV_FREE>.
		2069
		2070	On systems that do not implement C<posix_madvise>, this function returns
		2071	ENOSYS, otherwise the return value of C<posix_madvise>.
		2072
		2073	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2074
		2075	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2076	$scalar (see its manpage for details). The following protect
		2077	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2078	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2079
		2080	On systems that do not implement C<mprotect>, this function returns
		2081	ENOSYS, otherwise the return value of C<mprotect>.
		2082
		2083	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2084
		2085	Memory-maps a file (or anonymous memory range) and attaches it to the
		2086	given C<$scalar>, which will act like a string scalar. Returns true on
		2087	success, and false otherwise.
		2088
		2089	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		2090	change the string length, and most read-only operations such as copying it
		2091	or searching it with regexes and so on.
		2092
		2093	Anything else is unsafe and will, at best, result in memory leaks.
		2094
		2095	The memory map associated with the C<$scalar> is automatically removed
		2096	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		2097	C<IO::AIO::munmap> functions are called.
		2098
		2099	This calls the C<mmap>(2) function internally. See your system's manual
		2100	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2101
		2102	The C<$length> must be larger than zero and smaller than the actual
		2103	filesize.
		2104
		2105	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2106	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2107
		2108	C<$flags> can be a combination of
		2109	C<IO::AIO::MAP_SHARED> or
		2110	C<IO::AIO::MAP_PRIVATE>,
		2111	or a number of system-specific flags (when not available, the are C<0>):
		2112	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
		2113	C<IO::AIO::MAP_LOCKED>,
		2114	C<IO::AIO::MAP_NORESERVE>,
		2115	C<IO::AIO::MAP_POPULATE>,
		2116	C<IO::AIO::MAP_NONBLOCK>,
		2117	C<IO::AIO::MAP_FIXED>,
		2118	C<IO::AIO::MAP_GROWSDOWN>,
		2119	C<IO::AIO::MAP_32BIT>,
		2120	C<IO::AIO::MAP_HUGETLB> or
		2121	C<IO::AIO::MAP_STACK>.
		2122
		2123	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2124
		2125	C<$offset> is the offset from the start of the file - it generally must be
		2126	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2127
		2128	Example:
		2129
		2130	use Digest::MD5;
		2131	use IO::AIO;
		2132
		2133	open my $fh, "<verybigfile"
		2134	or die "$!";
		2135
		2136	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2137	or die "verybigfile: $!";
		2138
		2139	my $fast_md5 = md5 $data;
		2140
		2141	=item IO::AIO::munmap $scalar
		2142
		2143	Removes a previous mmap and undefines the C<$scalar>.
		2144
		2145	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2146
		2147	Calls the C<munlock> function, undoing the effects of a previous
		2148	C<aio_mlock> call (see its description for details).
		2149
		2150	=item IO::AIO::munlockall
		2151
		2152	Calls the C<munlockall> function.
		2153
		2154	On systems that do not implement C<munlockall>, this function returns
		2155	ENOSYS, otherwise the return value of C<munlockall>.
		2156
		2157	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2158
		2159	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2160	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2161	should be the file offset.
		2162
		2163	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2164	silently corrupt the data in this case.
		2165
		2166	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2167	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2168	C<IO::AIO::SPLICE_F_GIFT>.
		2169
		2170	See the C<splice(2)> manpage for details.
		2171
		2172	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2173
		2174	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2175	description for C<IO::AIO::splice> above for details.
		2176
		2177	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2178
		2179	Attempts to query or change the pipe buffer size. Obviously works only
		2180	on pipes, and currently works only on GNU/Linux systems, and fails with
		2181	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2182	size on other systems, drop me a note.
		2183
		2184	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2185
		2186	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2187	C<$flags> is missing or C<0>, then this should be the same as a call to
		2188	perl's built-in C<pipe> function and create a new pipe, and works on
		2189	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2190	(..., 4096, O_BINARY)>.
		2191
		2192	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2193	the given flags (Linux 2.6.27, glibc 2.9).
		2194
		2195	On success, the read and write file handles are returned.
		2196
		2197	On error, nothing will be returned. If the pipe2 syscall is missing and
		2198	C<$flags> is non-zero, fails with C<ENOSYS>.
		2199
		2200	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2201	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2202	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2203
		2204	=back
		2205
1399	=cut	2206	=cut
1400		2207
1401	min_parallel 8;	2208	min_parallel 8;
1402		2209
1403	END { flush }	2210	END { flush }
1404		2211
1405	1;	2212	1;
1406		2213
		2214	=head1 EVENT LOOP INTEGRATION
		2215
		2216	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2217	automatically into many event loops:
		2218
		2219	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2220	use AnyEvent::AIO;
		2221
		2222	You can also integrate IO::AIO manually into many event loops, here are
		2223	some examples of how to do this:
		2224
		2225	# EV integration
		2226	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2227
		2228	# Event integration
		2229	Event->io (fd => IO::AIO::poll_fileno,
		2230	poll => 'r',
		2231	cb => \&IO::AIO::poll_cb);
		2232
		2233	# Glib/Gtk2 integration
		2234	add_watch Glib::IO IO::AIO::poll_fileno,
		2235	in => sub { IO::AIO::poll_cb; 1 };
		2236
		2237	# Tk integration
		2238	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2239	readable => \&IO::AIO::poll_cb);
		2240
		2241	# Danga::Socket integration
		2242	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2243	\&IO::AIO::poll_cb);
		2244
1407	=head2 FORK BEHAVIOUR	2245	=head2 FORK BEHAVIOUR
1408		2246
1409	This module should do "the right thing" when the process using it forks:	2247	Usage of pthreads in a program changes the semantics of fork
		2248	considerably. Specifically, only async-safe functions can be called after
		2249	fork. Perl doesn't know about this, so in general, you cannot call fork
		2250	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2251	pthreads, so this applies, but many other extensions and (for inexplicable
		2252	reasons) perl itself often is linked against pthreads, so this limitation
		2253	applies to quite a lot of perls.
1410		2254
1411	Before the fork, IO::AIO enters a quiescent state where no requests	2255	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1412	can be added in other threads and no results will be processed. After	2256	only works in the process that loaded it. Forking is fully supported, but
1413	the fork the parent simply leaves the quiescent state and continues	2257	using IO::AIO in the child is not.
1414	request/result processing, while the child frees the request/result queue
1415	(so that the requests started before the fork will only be handled in the
1416	parent). Threads will be started on demand until the limit set in the
1417	parent process has been reached again.
1418		2258
1419	In short: the parent will, after a short pause, continue as if fork had	2259	You might get around by not I<using> IO::AIO before (or after)
1420	not been called, while the child will act as if IO::AIO has not been used	2260	forking. You could also try to call the L<IO::AIO::reinit> function in the
1421	yet.	2261	child:
		2262
		2263	=over 4
		2264
		2265	=item IO::AIO::reinit
		2266
		2267	Abandons all current requests and I/O threads and simply reinitialises all
		2268	data structures. This is not an operation supported by any standards, but
		2269	happens to work on GNU/Linux and some newer BSD systems.
		2270
		2271	The only reasonable use for this function is to call it after forking, if
		2272	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2273	the process will result in undefined behaviour. Calling it at any time
		2274	will also result in any undefined (by POSIX) behaviour.
		2275
		2276	=back
1422		2277
1423	=head2 MEMORY USAGE	2278	=head2 MEMORY USAGE
1424		2279
1425	Per-request usage:	2280	Per-request usage:
1426		2281

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines