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Revision 1.145 by root, Sun Apr 19 19:20:10 2009 UTC vs.
Revision 1.228 by root, Sun Jun 17 17:07:25 2012 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;	73	use Fcntl;
96	use Event;	74	use EV;
97	use IO::AIO;	75	use IO::AIO;
98		76
99	# register the IO::AIO callback with Event	77	# register the IO::AIO callback with EV
100	Event->io (fd => IO::AIO::poll_fileno,	78	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		79
104	# queue the request to open /etc/passwd	80	# queue the request to open /etc/passwd
105	aio_open "/etc/passwd", O_RDONLY, 0, sub {	81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106	my $fh = shift	82	my $fh = shift
107	or die "error while opening: $!";	83	or die "error while opening: $!";
108		84
109	# stat'ing filehandles is generally non-blocking	85	# stat'ing filehandles is generally non-blocking
110	my $size = -s $fh;	86	my $size = -s $fh;
…		…
119		95
120	# file contents now in $contents	96	# file contents now in $contents
121	print $contents;	97	print $contents;
122		98
123	# exit event loop and program	99	# exit event loop and program
124	Event::unloop;	100	EV::unloop;
125	};	101	};
126	};	102	};
127		103
128	# possibly queue up other requests, or open GUI windows,	104	# possibly queue up other requests, or open GUI windows,
129	# check for sockets etc. etc.	105	# check for sockets etc. etc.
130		106
131	# process events as long as there are some:	107	# process events as long as there are some:
132	Event::loop;	108	EV::loop;
133		109
134	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
135		111
136	Every C<aio_*> function creates a request. which is a C data structure not	112	Every C<aio_*> function creates a request. which is a C data structure not
137	directly visible to Perl.	113	directly visible to Perl.
…		…
187		163
188	package IO::AIO;	164	package IO::AIO;
189		165
190	use Carp ();	166	use Carp ();
191		167
192	no warnings;	168	use common::sense;
193	use strict 'vars';
194		169
195	use base 'Exporter';	170	use base 'Exporter';
196		171
197	BEGIN {	172	BEGIN {
198	our $VERSION = '3.18';	173	our $VERSION = '4.15';
199		174
200	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	175	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	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
203	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
		179	aio_pathsync aio_readahead aio_fiemap
204	aio_rename aio_link aio_move aio_copy aio_group	180	aio_rename aio_link aio_move aio_copy aio_group
205	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206	aio_chmod aio_utime aio_truncate);	182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
		184	aio_statvfs
		185	aio_wd);
207		186
208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210	min_parallel max_parallel max_idle	189	min_parallel max_parallel max_idle idle_timeout
211	nreqs nready npending nthreads	190	nreqs nready npending nthreads
212	max_poll_time max_poll_reqs);	191	max_poll_time max_poll_reqs
		192	sendfile fadvise madvise
		193	mmap munmap munlock munlockall);
213		194
214	push @AIO_REQ, qw(aio_busy); # not exported	195	push @AIO_REQ, qw(aio_busy); # not exported
215		196
216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217		198
…		…
219	XSLoader::load ("IO::AIO", $VERSION);	200	XSLoader::load ("IO::AIO", $VERSION);
220	}	201	}
221		202
222	=head1 FUNCTIONS	203	=head1 FUNCTIONS
223		204
224	=head2 AIO REQUEST FUNCTIONS	205	=head2 QUICK OVERVIEW
		206
		207	This section simply lists the prototypes of the most important functions
		208	for quick reference. See the following sections for function-by-function
		209	documentation.
		210
		211	aio_wd $pathname, $callback->($wd)
		212	aio_open $pathname, $flags, $mode, $callback->($fh)
		213	aio_close $fh, $callback->($status)
		214	aio_seek $fh,$offset,$whence, $callback->($offs)
		215	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		217	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		218	aio_readahead $fh,$offset,$length, $callback->($retval)
		219	aio_stat $fh_or_path, $callback->($status)
		220	aio_lstat $fh, $callback->($status)
		221	aio_statvfs $fh_or_path, $callback->($statvfs)
		222	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		223	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		224	aio_chmod $fh_or_path, $mode, $callback->($status)
		225	aio_truncate $fh_or_path, $offset, $callback->($status)
		226	aio_unlink $pathname, $callback->($status)
		227	aio_mknod $pathname, $mode, $dev, $callback->($status)
		228	aio_link $srcpath, $dstpath, $callback->($status)
		229	aio_symlink $srcpath, $dstpath, $callback->($status)
		230	aio_readlink $pathname, $callback->($link)
		231	aio_realpath $pathname, $callback->($link)
		232	aio_rename $srcpath, $dstpath, $callback->($status)
		233	aio_mkdir $pathname, $mode, $callback->($status)
		234	aio_rmdir $pathname, $callback->($status)
		235	aio_readdir $pathname, $callback->($entries)
		236	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		237	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		238	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		239	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		240	aio_load $pathname, $data, $callback->($status)
		241	aio_copy $srcpath, $dstpath, $callback->($status)
		242	aio_move $srcpath, $dstpath, $callback->($status)
		243	aio_rmtree $pathname, $callback->($status)
		244	aio_sync $callback->($status)
		245	aio_syncfs $fh, $callback->($status)
		246	aio_fsync $fh, $callback->($status)
		247	aio_fdatasync $fh, $callback->($status)
		248	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		249	aio_pathsync $pathname, $callback->($status)
		250	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		251	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		252	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		253	aio_mlockall $flags, $callback->($status)
		254	aio_group $callback->(...)
		255	aio_nop $callback->()
		256
		257	$prev_pri = aioreq_pri [$pri]
		258	aioreq_nice $pri_adjust
		259
		260	IO::AIO::poll_wait
		261	IO::AIO::poll_cb
		262	IO::AIO::poll
		263	IO::AIO::flush
		264	IO::AIO::max_poll_reqs $nreqs
		265	IO::AIO::max_poll_time $seconds
		266	IO::AIO::min_parallel $nthreads
		267	IO::AIO::max_parallel $nthreads
		268	IO::AIO::max_idle $nthreads
		269	IO::AIO::idle_timeout $seconds
		270	IO::AIO::max_outstanding $maxreqs
		271	IO::AIO::nreqs
		272	IO::AIO::nready
		273	IO::AIO::npending
		274
		275	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		276	IO::AIO::fadvise $fh, $offset, $len, $advice
		277	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		278	IO::AIO::munmap $scalar
		279	IO::AIO::madvise $scalar, $offset, $length, $advice
		280	IO::AIO::mprotect $scalar, $offset, $length, $protect
		281	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		282	IO::AIO::munlockall
		283
		284	=head2 API NOTES
225		285
226	All the C<aio_*> calls are more or less thin wrappers around the syscall	286	All the C<aio_*> calls are more or less thin wrappers around the syscall
227	with the same name (sans C<aio_>). The arguments are similar or identical,	287	with the same name (sans C<aio_>). The arguments are similar or identical,
228	and they all accept an additional (and optional) C<$callback> argument	288	and they all accept an additional (and optional) C<$callback> argument
229	which must be a code reference. This code reference will get called with	289	which must be a code reference. This code reference will be called after
230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	290	the syscall has been executed in an asynchronous fashion. The results
231	perl, which usually delivers "false") as its sole argument after the given	291	of the request will be passed as arguments to the callback (and, if an
232	syscall has been executed asynchronously.	292	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		293	most syscalls return C<-1> on error, unlike perl, which usually delivers
		294	"false").
		295
		296	Some requests (such as C<aio_readdir>) pass the actual results and
		297	communicate failures by passing C<undef>.
233		298
234	All functions expecting a filehandle keep a copy of the filehandle	299	All functions expecting a filehandle keep a copy of the filehandle
235	internally until the request has finished.	300	internally until the request has finished.
236		301
237	All functions return request objects of type L<IO::AIO::REQ> that allow	302	All functions return request objects of type L<IO::AIO::REQ> that allow
238	further manipulation of those requests while they are in-flight.	303	further manipulation of those requests while they are in-flight.
239		304
240	The pathnames you pass to these routines I<must> be absolute and	305	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	306	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	307	current working directory could have changed. Alternatively, you can
243	changed. Alternatively, you can make sure that you never change the	308	make sure that you never change the current working directory anywhere
244	current working directory anywhere in the program and then use relative	309	in the program and then use relative paths. You can also take advantage
245	paths.	310	of IO::AIOs working directory abstraction, that lets you specify paths
		311	relative to some previously-opened "working directory object" - see the
		312	description of the C<IO::AIO::WD> class later in this document.
246		313
247	To encode pathnames as octets, either make sure you either: a) always pass	314	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	315	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	316	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	317	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)	318	effect in the user environment, d) use Glib::filename_from_unicode on
252	use something else to ensure your scalar has the correct contents.	319	unicode filenames or e) use something else to ensure your scalar has the
		320	correct contents.
253		321
254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	322	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255	handles correctly whether it is set or not.	323	handles correctly whether it is set or not.
		324
		325	=head2 AIO REQUEST FUNCTIONS
256		326
257	=over 4	327	=over 4
258		328
259	=item $prev_pri = aioreq_pri [$pri]	329	=item $prev_pri = aioreq_pri [$pri]
260		330
…		…
307	by the umask in effect then the request is being executed, so better never	377	by the umask in effect then the request is being executed, so better never
308	change the umask.	378	change the umask.
309		379
310	Example:	380	Example:
311		381
312	aio_open "/etc/passwd", O_RDONLY, 0, sub {	382	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313	if ($_[0]) {	383	if ($_[0]) {
314	print "open successful, fh is $_[0]\n";	384	print "open successful, fh is $_[0]\n";
315	...	385	...
316	} else {	386	} else {
317	die "open failed: $!\n";	387	die "open failed: $!\n";
318	}	388	}
319	};	389	};
320		390
		391	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		392	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		393	following POSIX and non-POSIX constants are available (missing ones on
		394	your system are, as usual, C<0>):
		395
		396	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		397	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		398	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		399
321		400
322	=item aio_close $fh, $callback->($status)	401	=item aio_close $fh, $callback->($status)
323		402
324	Asynchronously close a file and call the callback with the result	403	Asynchronously close a file and call the callback with the result
325	code.	404	code.
…		…
333		412
334	Or in other words: the file descriptor will be closed, but it will not be	413	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.	414	free for reuse until the perl filehandle is closed.
336		415
337	=cut	416	=cut
		417
		418	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		419
		420	Seeks the filehandle to the new C<$offset>, similarly to perl's
		421	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		422	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		423	C<IO::AIO::SEEK_END>).
		424
		425	The resulting absolute offset will be passed to the callback, or C<-1> in
		426	case of an error.
		427
		428	In theory, the C<$whence> constants could be different than the
		429	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		430	so don't panic.
		431
		432	As a GNU/Linux (and maybe Solaris) extension, also the constants
		433	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		434	could be found. No guarantees about suitability for use in C<aio_seek> or
		435	Perl's C<sysseek> can be made though, although I would naively assume they
		436	"just work".
338		437
339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	438	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		439
341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	440	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342		441
343	Reads or writes C<$length> bytes from or to the specified C<$fh> and	442	Reads or writes C<$length> bytes from or to the specified C<$fh> and
344	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	443	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
345	and calls the callback without the actual number of bytes read (or -1 on	444	and calls the callback without the actual number of bytes read (or -1 on
346	error, just like the syscall).	445	error, just like the syscall).
347		446
		447	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		448	offset plus the actual number of bytes read.
		449
348	If C<$offset> is undefined, then the current file descriptor offset will	450	If C<$offset> is undefined, then the current file descriptor offset will
349	be used (and updated), otherwise the file descriptor offset will not be	451	be used (and updated), otherwise the file descriptor offset will not be
350	changed by these calls.	452	changed by these calls.
351		453
352	If C<$length> is undefined in C<aio_write>, use the remaining length of	454	If C<$length> is undefined in C<aio_write>, use the remaining length of
…		…
372		474
373	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	475	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
374	reading at byte offset C<$in_offset>, and starts writing at the current	476	reading at byte offset C<$in_offset>, and starts writing at the current
375	file offset of C<$out_fh>. Because of that, it is not safe to issue more	477	file offset of C<$out_fh>. Because of that, it is not safe to issue more
376	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	478	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
377	other.	479	other. The same C<$in_fh> works fine though, as this function does not
		480	move or use the file offset of C<$in_fh>.
378		481
		482	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		483	are written, and there is no way to find out how many more bytes have been
		484	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		485	number of bytes written to C<$out_fh>. Only if the result value equals
		486	C<$length> one can assume that C<$length> bytes have been read.
		487
		488	Unlike with other C<aio_> functions, it makes a lot of sense to use
		489	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		490	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		491	the socket I/O will be non-blocking. Note, however, that you can run
		492	into a trap where C<aio_sendfile> reads some data with readahead, then
		493	fails to write all data, and when the socket is ready the next time, the
		494	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		495	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		496	resource usage.
		497
379	This call tries to make use of a native C<sendfile> syscall to provide	498	This call tries to make use of a native C<sendfile>-like syscall to
380	zero-copy operation. For this to work, C<$out_fh> should refer to a	499	provide zero-copy operation. For this to work, C<$out_fh> should refer to
381	socket, and C<$in_fh> should refer to mmap'able file.	500	a socket, and C<$in_fh> should refer to an mmap'able file.
382		501
383	If the native sendfile call fails or is not implemented, it will be	502	If a native sendfile cannot be found or it fails with C<ENOSYS>,
384	emulated, so you can call C<aio_sendfile> on any type of filehandle	503	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		504	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
385	regardless of the limitations of the operating system.	505	type of filehandle regardless of the limitations of the operating system.
386		506
387	Please note, however, that C<aio_sendfile> can read more bytes from	507	As native sendfile syscalls (as practically any non-POSIX interface hacked
388	C<$in_fh> than are written, and there is no way to find out how many	508	together in a hurry to improve benchmark numbers) tend to be rather buggy
389	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	509	on many systems, this implementation tries to work around some known bugs
390	provides the number of bytes written to C<$out_fh>. Only if the result	510	in Linux and FreeBSD kernels (probably others, too), but that might fail,
391	value equals C<$length> one can assume that C<$length> bytes have been	511	so you really really should check the return value of C<aio_sendfile> -
392	read.	512	fewre bytes than expected might have been transferred.
393		513
394		514
395	=item aio_readahead $fh,$offset,$length, $callback->($retval)	515	=item aio_readahead $fh,$offset,$length, $callback->($retval)
396		516
397	C<aio_readahead> populates the page cache with data from a file so that	517	C<aio_readahead> populates the page cache with data from a file so that
…		…
420		540
421	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	541	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
422	error when stat'ing a large file, the results will be silently truncated	542	error when stat'ing a large file, the results will be silently truncated
423	unless perl itself is compiled with large file support.	543	unless perl itself is compiled with large file support.
424		544
		545	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		546	following constants and functions (if not implemented, the constants will
		547	be C<0> and the functions will either C<croak> or fall back on traditional
		548	behaviour).
		549
		550	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		551	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		552	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		553
425	Example: Print the length of F</etc/passwd>:	554	Example: Print the length of F</etc/passwd>:
426		555
427	aio_stat "/etc/passwd", sub {	556	aio_stat "/etc/passwd", sub {
428	$_[0] and die "stat failed: $!";	557	$_[0] and die "stat failed: $!";
429	print "size is ", -s _, "\n";	558	print "size is ", -s _, "\n";
430	};	559	};
431		560
432		561
		562	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		563
		564	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		565	whether a file handle or path was passed.
		566
		567	On success, the callback is passed a hash reference with the following
		568	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		569	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		570	is passed.
		571
		572	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		573	C<ST_NOSUID>.
		574
		575	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		576	their correct value when available, or to C<0> on systems that do
		577	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		578	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		579	C<ST_NODIRATIME> and C<ST_RELATIME>.
		580
		581	Example: stat C</wd> and dump out the data if successful.
		582
		583	aio_statvfs "/wd", sub {
		584	my $f = $_[0]
		585	or die "statvfs: $!";
		586
		587	use Data::Dumper;
		588	say Dumper $f;
		589	};
		590
		591	# result:
		592	{
		593	bsize => 1024,
		594	bfree => 4333064312,
		595	blocks => 10253828096,
		596	files => 2050765568,
		597	flag => 4096,
		598	favail => 2042092649,
		599	bavail => 4333064312,
		600	ffree => 2042092649,
		601	namemax => 255,
		602	frsize => 1024,
		603	fsid => 1810
		604	}
		605
		606
433	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	607	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
434		608
435	Works like perl's C<utime> function (including the special case of $atime	609	Works like perl's C<utime> function (including the special case of $atime
436	and $mtime being undef). Fractional times are supported if the underlying	610	and $mtime being undef). Fractional times are supported if the underlying
437	syscalls support them.	611	syscalls support them.
…		…
475		649
476	Asynchronously unlink (delete) a file and call the callback with the	650	Asynchronously unlink (delete) a file and call the callback with the
477	result code.	651	result code.
478		652
479		653
480	=item aio_mknod $path, $mode, $dev, $callback->($status)	654	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
481		655
482	[EXPERIMENTAL]	656	[EXPERIMENTAL]
483		657
484	Asynchronously create a device node (or fifo). See mknod(2).	658	Asynchronously create a device node (or fifo). See mknod(2).
485		659
486	The only (POSIX-) portable way of calling this function is:	660	The only (POSIX-) portable way of calling this function is:
487		661
488	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	662	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
489		663
		664	See C<aio_stat> for info about some potentially helpful extra constants
		665	and functions.
490		666
491	=item aio_link $srcpath, $dstpath, $callback->($status)	667	=item aio_link $srcpath, $dstpath, $callback->($status)
492		668
493	Asynchronously create a new link to the existing object at C<$srcpath> at	669	Asynchronously create a new link to the existing object at C<$srcpath> at
494	the path C<$dstpath> and call the callback with the result code.	670	the path C<$dstpath> and call the callback with the result code.
…		…
498		674
499	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	675	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
500	the path C<$dstpath> and call the callback with the result code.	676	the path C<$dstpath> and call the callback with the result code.
501		677
502		678
503	=item aio_readlink $path, $callback->($link)	679	=item aio_readlink $pathname, $callback->($link)
504		680
505	Asynchronously read the symlink specified by C<$path> and pass it to	681	Asynchronously read the symlink specified by C<$path> and pass it to
506	the callback. If an error occurs, nothing or undef gets passed to the	682	the callback. If an error occurs, nothing or undef gets passed to the
507	callback.	683	callback.
508		684
509		685
		686	=item aio_realpath $pathname, $callback->($path)
		687
		688	Asynchronously make the path absolute and resolve any symlinks in
		689	C<$path>. The resulting path only consists of directories (Same as
		690	L<Cwd::realpath>).
		691
		692	This request can be used to get the absolute path of the current working
		693	directory by passing it a path of F<.> (a single dot).
		694
		695
510	=item aio_rename $srcpath, $dstpath, $callback->($status)	696	=item aio_rename $srcpath, $dstpath, $callback->($status)
511		697
512	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	698	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
513	rename(2) and call the callback with the result code.	699	rename(2) and call the callback with the result code.
514		700
…		…
530		716
531	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	717	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
532	directory (i.e. opendir + readdir + closedir). The entries will not be	718	directory (i.e. opendir + readdir + closedir). The entries will not be
533	sorted, and will B<NOT> include the C<.> and C<..> entries.	719	sorted, and will B<NOT> include the C<.> and C<..> entries.
534		720
535	The callback a single argument which is either C<undef> or an array-ref	721	The callback is passed a single argument which is either C<undef> or an
536	with the filenames.	722	array-ref with the filenames.
537		723
538		724
		725	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		726
		727	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		728	tune behaviour and output format. In case of an error, C<$entries> will be
		729	C<undef>.
		730
		731	The flags are a combination of the following constants, ORed together (the
		732	flags will also be passed to the callback, possibly modified):
		733
		734	=over 4
		735
		736	=item IO::AIO::READDIR_DENTS
		737
		738	When this flag is off, then the callback gets an arrayref consisting of
		739	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		740	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		741	entry in more detail.
		742
		743	C<$name> is the name of the entry.
		744
		745	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		746
		747	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		748	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		749	C<IO::AIO::DT_WHT>.
		750
		751	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		752	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		753	scalars are read-only: you can not modify them.
		754
		755	C<$inode> is the inode number (which might not be exact on systems with 64
		756	bit inode numbers and 32 bit perls). This field has unspecified content on
		757	systems that do not deliver the inode information.
		758
		759	=item IO::AIO::READDIR_DIRS_FIRST
		760
		761	When this flag is set, then the names will be returned in an order where
		762	likely directories come first, in optimal stat order. This is useful when
		763	you need to quickly find directories, or you want to find all directories
		764	while avoiding to stat() each entry.
		765
		766	If the system returns type information in readdir, then this is used
		767	to find directories directly. Otherwise, likely directories are names
		768	beginning with ".", or otherwise names with no dots, of which names with
		769	short names are tried first.
		770
		771	=item IO::AIO::READDIR_STAT_ORDER
		772
		773	When this flag is set, then the names will be returned in an order
		774	suitable for stat()'ing each one. That is, when you plan to stat()
		775	all files in the given directory, then the returned order will likely
		776	be fastest.
		777
		778	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		779	the likely dirs come first, resulting in a less optimal stat order.
		780
		781	=item IO::AIO::READDIR_FOUND_UNKNOWN
		782
		783	This flag should not be set when calling C<aio_readdirx>. Instead, it
		784	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		785	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		786	C<$type>'s are known, which can be used to speed up some algorithms.
		787
		788	=back
		789
		790
539	=item aio_load $path, $data, $callback->($status)	791	=item aio_load $pathname, $data, $callback->($status)
540		792
541	This is a composite request that tries to fully load the given file into	793	This is a composite request that tries to fully load the given file into
542	memory. Status is the same as with aio_read.	794	memory. Status is the same as with aio_read.
543		795
544	=cut	796	=cut
…		…
566		818
567	=item aio_copy $srcpath, $dstpath, $callback->($status)	819	=item aio_copy $srcpath, $dstpath, $callback->($status)
568		820
569	Try to copy the I<file> (directories not supported as either source or	821	Try to copy the I<file> (directories not supported as either source or
570	destination) from C<$srcpath> to C<$dstpath> and call the callback with	822	destination) from C<$srcpath> to C<$dstpath> and call the callback with
571	the C<0> (error) or C<-1> ok.	823	a status of C<0> (ok) or C<-1> (error, see C<$!>).
572		824
573	This is a composite request that creates the destination file with	825	This is a composite request that creates the destination file with
574	mode 0200 and copies the contents of the source file into it using	826	mode 0200 and copies the contents of the source file into it using
575	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	827	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
576	uid/gid, in that order.	828	uid/gid, in that order.
…		…
588	my $grp = aio_group $cb;	840	my $grp = aio_group $cb;
589		841
590	aioreq_pri $pri;	842	aioreq_pri $pri;
591	add $grp aio_open $src, O_RDONLY, 0, sub {	843	add $grp aio_open $src, O_RDONLY, 0, sub {
592	if (my $src_fh = $_[0]) {	844	if (my $src_fh = $_[0]) {
593	my @stat = stat $src_fh;	845	my @stat = stat $src_fh; # hmm, might block over nfs?
594		846
595	aioreq_pri $pri;	847	aioreq_pri $pri;
596	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	848	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
597	if (my $dst_fh = $_[0]) {	849	if (my $dst_fh = $_[0]) {
598	aioreq_pri $pri;	850	aioreq_pri $pri;
599	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	851	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
600	if ($_[0] == $stat[7]) {	852	if ($_[0] == $stat[7]) {
601	$grp->result (0);	853	$grp->result (0);
602	close $src_fh;	854	close $src_fh;
603		855
604	# those should not normally block. should. should.	856	my $ch = sub {
605	utime $stat[8], $stat[9], $dst;	857	aioreq_pri $pri;
606	chmod $stat[2] & 07777, $dst_fh;	858	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
607	chown $stat[4], $stat[5], $dst_fh;	859	aioreq_pri $pri;
		860	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		861	aioreq_pri $pri;
		862	add $grp aio_close $dst_fh;
		863	}
		864	};
		865	};
608		866
609	aioreq_pri $pri;	867	aioreq_pri $pri;
610	add $grp aio_close $dst_fh;	868	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		869	if ($_[0] < 0 && $! == ENOSYS) {
		870	aioreq_pri $pri;
		871	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		872	} else {
		873	$ch->();
		874	}
		875	};
611	} else {	876	} else {
612	$grp->result (-1);	877	$grp->result (-1);
613	close $src_fh;	878	close $src_fh;
614	close $dst_fh;	879	close $dst_fh;
615		880
…		…
632		897
633	=item aio_move $srcpath, $dstpath, $callback->($status)	898	=item aio_move $srcpath, $dstpath, $callback->($status)
634		899
635	Try to move the I<file> (directories not supported as either source or	900	Try to move the I<file> (directories not supported as either source or
636	destination) from C<$srcpath> to C<$dstpath> and call the callback with	901	destination) from C<$srcpath> to C<$dstpath> and call the callback with
637	the C<0> (error) or C<-1> ok.	902	a status of C<0> (ok) or C<-1> (error, see C<$!>).
638		903
639	This is a composite request that tries to rename(2) the file first; if	904	This is a composite request that tries to rename(2) the file first; if
640	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	905	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
641	that is successful, unlinks the C<$srcpath>.	906	that is successful, unlinks the C<$srcpath>.
642		907
…		…
653	if ($_[0] && $! == EXDEV) {	918	if ($_[0] && $! == EXDEV) {
654	aioreq_pri $pri;	919	aioreq_pri $pri;
655	add $grp aio_copy $src, $dst, sub {	920	add $grp aio_copy $src, $dst, sub {
656	$grp->result ($_[0]);	921	$grp->result ($_[0]);
657		922
658	if (!$_[0]) {	923	unless ($_[0]) {
659	aioreq_pri $pri;	924	aioreq_pri $pri;
660	add $grp aio_unlink $src;	925	add $grp aio_unlink $src;
661	}	926	}
662	};	927	};
663	} else {	928	} else {
…		…
666	};	931	};
667		932
668	$grp	933	$grp
669	}	934	}
670		935
671	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	936	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
672		937
673	Scans a directory (similar to C<aio_readdir>) but additionally tries to	938	Scans a directory (similar to C<aio_readdir>) but additionally tries to
674	efficiently separate the entries of directory C<$path> into two sets of	939	efficiently separate the entries of directory C<$path> into two sets of
675	names, directories you can recurse into (directories), and ones you cannot	940	names, directories you can recurse into (directories), and ones you cannot
676	recurse into (everything else, including symlinks to directories).	941	recurse into (everything else, including symlinks to directories).
…		…
693		958
694	Implementation notes.	959	Implementation notes.
695		960
696	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	961	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
697		962
		963	If readdir returns file type information, then this is used directly to
		964	find directories.
		965
698	After reading the directory, the modification time, size etc. of the	966	Otherwise, after reading the directory, the modification time, size etc.
699	directory before and after the readdir is checked, and if they match (and	967	of the directory before and after the readdir is checked, and if they
700	isn't the current time), the link count will be used to decide how many	968	match (and isn't the current time), the link count will be used to decide
701	entries are directories (if >= 2). Otherwise, no knowledge of the number	969	how many entries are directories (if >= 2). Otherwise, no knowledge of the
702	of subdirectories will be assumed.	970	number of subdirectories will be assumed.
703		971
704	Then entries will be sorted into likely directories (everything without	972	Then entries will be sorted into likely directories a non-initial dot
705	a non-initial dot currently) and likely non-directories (everything	973	currently) and likely non-directories (see C<aio_readdirx>). Then every
706	else). Then every entry plus an appended C</.> will be C<stat>'ed,	974	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
707	likely directories first. If that succeeds, it assumes that the entry	975	in order of their inode numbers. If that succeeds, it assumes that the
708	is a directory or a symlink to directory (which will be checked	976	entry is a directory or a symlink to directory (which will be checked
709	seperately). This is often faster than stat'ing the entry itself because	977	separately). This is often faster than stat'ing the entry itself because
710	filesystems might detect the type of the entry without reading the inode	978	filesystems might detect the type of the entry without reading the inode
711	data (e.g. ext2fs filetype feature).	979	data (e.g. ext2fs filetype feature), even on systems that cannot return
		980	the filetype information on readdir.
712		981
713	If the known number of directories (link count - 2) has been reached, the	982	If the known number of directories (link count - 2) has been reached, the
714	rest of the entries is assumed to be non-directories.	983	rest of the entries is assumed to be non-directories.
715		984
716	This only works with certainty on POSIX (= UNIX) filesystems, which	985	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
729		998
730	my $grp = aio_group $cb;	999	my $grp = aio_group $cb;
731		1000
732	$maxreq = 4 if $maxreq <= 0;	1001	$maxreq = 4 if $maxreq <= 0;
733		1002
734	# stat once	1003	# get a wd object
735	aioreq_pri $pri;	1004	aioreq_pri $pri;
736	add $grp aio_stat $path, sub {	1005	add $grp aio_wd $path, sub {
		1006	$_[0]
737	return $grp->result () if $_[0];	1007	or return $grp->result ();
738	my $now = time;
739	my $hash1 = join ":", (stat _)[0,1,3,7,9];
740		1008
741	# read the directory entries	1009	my $wd = [shift, "."];
		1010
		1011	# stat once
742	aioreq_pri $pri;	1012	aioreq_pri $pri;
743	add $grp aio_readdir $path, sub {	1013	add $grp aio_stat $wd, sub {
744	my $entries = shift
745	or return $grp->result ();	1014	return $grp->result () if $_[0];
		1015	my $now = time;
		1016	my $hash1 = join ":", (stat _)[0,1,3,7,9];
746		1017
747	# stat the dir another time	1018	# read the directory entries
748	aioreq_pri $pri;	1019	aioreq_pri $pri;
		1020	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1021	my $entries = shift
		1022	or return $grp->result ();
		1023
		1024	# stat the dir another time
		1025	aioreq_pri $pri;
749	add $grp aio_stat $path, sub {	1026	add $grp aio_stat $wd, sub {
750	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1027	my $hash2 = join ":", (stat _)[0,1,3,7,9];
751		1028
752	my $ndirs;	1029	my $ndirs;
753		1030
754	# take the slow route if anything looks fishy	1031	# take the slow route if anything looks fishy
755	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1032	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
756	$ndirs = -1;	1033	$ndirs = -1;
757	} else {	1034	} else {
758	# if nlink == 2, we are finished	1035	# if nlink == 2, we are finished
759	# on non-posix-fs's, we rely on nlink < 2	1036	# for non-posix-fs's, we rely on nlink < 2
760	$ndirs = (stat _)[3] - 2	1037	$ndirs = (stat _)[3] - 2
761	or return $grp->result ([], $entries);	1038	or return $grp->result ([], $entries);
762	}	1039	}
763		1040
764	# sort into likely dirs and likely nondirs
765	# dirs == files without ".", short entries first
766	$entries = [map $_->[0],
767	sort { $b->[1] cmp $a->[1] }
768	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
769	@$entries];
770
771	my (@dirs, @nondirs);	1041	my (@dirs, @nondirs);
772		1042
773	my $statgrp = add $grp aio_group sub {	1043	my $statgrp = add $grp aio_group sub {
774	$grp->result (\@dirs, \@nondirs);	1044	$grp->result (\@dirs, \@nondirs);
775	};	1045	};
776		1046
777	limit $statgrp $maxreq;	1047	limit $statgrp $maxreq;
778	feed $statgrp sub {	1048	feed $statgrp sub {
779	return unless @$entries;	1049	return unless @$entries;
780	my $entry = pop @$entries;	1050	my $entry = shift @$entries;
781		1051
782	aioreq_pri $pri;	1052	aioreq_pri $pri;
		1053	$wd->[1] = "$entry/.";
783	add $statgrp aio_stat "$path/$entry/.", sub {	1054	add $statgrp aio_stat $wd, sub {
784	if ($_[0] < 0) {	1055	if ($_[0] < 0) {
785	push @nondirs, $entry;	1056	push @nondirs, $entry;
786	} else {	1057	} else {
787	# need to check for real directory	1058	# need to check for real directory
788	aioreq_pri $pri;	1059	aioreq_pri $pri;
		1060	$wd->[1] = $entry;
789	add $statgrp aio_lstat "$path/$entry", sub {	1061	add $statgrp aio_lstat $wd, sub {
790	if (-d _) {	1062	if (-d _) {
791	push @dirs, $entry;	1063	push @dirs, $entry;
792		1064
793	unless (--$ndirs) {	1065	unless (--$ndirs) {
794	push @nondirs, @$entries;	1066	push @nondirs, @$entries;
795	feed $statgrp;	1067	feed $statgrp;
		1068	}
		1069	} else {
		1070	push @nondirs, $entry;
796	}	1071	}
797	} else {
798	push @nondirs, $entry;
799	}	1072	}
800	}	1073	}
801	}	1074	};
802	};	1075	};
803	};	1076	};
804	};	1077	};
805	};	1078	};
806	};	1079	};
807		1080
808	$grp	1081	$grp
809	}	1082	}
810		1083
811	=item aio_rmtree $path, $callback->($status)	1084	=item aio_rmtree $pathname, $callback->($status)
812		1085
813	Delete a directory tree starting (and including) C<$path>, return the	1086	Delete a directory tree starting (and including) C<$path>, return the
814	status of the final C<rmdir> only. This is a composite request that	1087	status of the final C<rmdir> only. This is a composite request that
815	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1088	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
816	everything else.	1089	everything else.
…		…
858	callback with the fdatasync result code.	1131	callback with the fdatasync result code.
859		1132
860	If this call isn't available because your OS lacks it or it couldn't be	1133	If this call isn't available because your OS lacks it or it couldn't be
861	detected, it will be emulated by calling C<fsync> instead.	1134	detected, it will be emulated by calling C<fsync> instead.
862		1135
		1136	=item aio_syncfs $fh, $callback->($status)
		1137
		1138	Asynchronously call the syncfs syscall to sync the filesystem associated
		1139	to the given filehandle and call the callback with the syncfs result
		1140	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1141	errno to C<ENOSYS> nevertheless.
		1142
863	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1143	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
864		1144
865	Sync the data portion of the file specified by C<$offset> and C<$length>	1145	Sync the data portion of the file specified by C<$offset> and C<$length>
866	to disk (but NOT the metadata), by calling the Linux-specific	1146	to disk (but NOT the metadata), by calling the Linux-specific
867	sync_file_range call. If sync_file_range is not available or it returns	1147	sync_file_range call. If sync_file_range is not available or it returns
…		…
870	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1150	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
871	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1151	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
872	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1152	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
873	manpage for details.	1153	manpage for details.
874		1154
875	=item aio_pathsync $path, $callback->($status)	1155	=item aio_pathsync $pathname, $callback->($status)
876		1156
877	This request tries to open, fsync and close the given path. This is a	1157	This request tries to open, fsync and close the given path. This is a
878	composite request intended to sync directories after directory operations	1158	composite request intended to sync directories after directory operations
879	(E.g. rename). This might not work on all operating systems or have any	1159	(E.g. rename). This might not work on all operating systems or have any
880	specific effect, but usually it makes sure that directory changes get	1160	specific effect, but usually it makes sure that directory changes get
881	written to disc. It works for anything that can be opened for read-only,	1161	written to disc. It works for anything that can be opened for read-only,
882	not just directories.	1162	not just directories.
		1163
		1164	Future versions of this function might fall back to other methods when
		1165	C<fsync> on the directory fails (such as calling C<sync>).
883		1166
884	Passes C<0> when everything went ok, and C<-1> on error.	1167	Passes C<0> when everything went ok, and C<-1> on error.
885		1168
886	=cut	1169	=cut
887		1170
…		…
908	};	1191	};
909		1192
910	$grp	1193	$grp
911	}	1194	}
912		1195
		1196	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1197
		1198	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1199	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1200	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1201	scalar must only be modified in-place while an aio operation is pending on
		1202	it).
		1203
		1204	It calls the C<msync> function of your OS, if available, with the memory
		1205	area starting at C<$offset> in the string and ending C<$length> bytes
		1206	later. If C<$length> is negative, counts from the end, and if C<$length>
		1207	is C<undef>, then it goes till the end of the string. The flags can be
		1208	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1209	C<IO::AIO::MS_SYNC>.
		1210
		1211	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1212
		1213	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1214	scalars.
		1215
		1216	It touches (reads or writes) all memory pages in the specified
		1217	range inside the scalar. All caveats and parameters are the same
		1218	as for C<aio_msync>, above, except for flags, which must be either
		1219	C<0> (which reads all pages and ensures they are instantiated) or
		1220	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1221	writing an octet from it, which dirties the page).
		1222
		1223	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1224
		1225	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1226	scalars.
		1227
		1228	It reads in all the pages of the underlying storage into memory (if any)
		1229	and locks them, so they are not getting swapped/paged out or removed.
		1230
		1231	If C<$length> is undefined, then the scalar will be locked till the end.
		1232
		1233	On systems that do not implement C<mlock>, this function returns C<-1>
		1234	and sets errno to C<ENOSYS>.
		1235
		1236	Note that the corresponding C<munlock> is synchronous and is
		1237	documented under L<MISCELLANEOUS FUNCTIONS>.
		1238
		1239	Example: open a file, mmap and mlock it - both will be undone when
		1240	C<$data> gets destroyed.
		1241
		1242	open my $fh, "<", $path or die "$path: $!";
		1243	my $data;
		1244	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1245	aio_mlock $data; # mlock in background
		1246
		1247	=item aio_mlockall $flags, $callback->($status)
		1248
		1249	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1250	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1251
		1252	On systems that do not implement C<mlockall>, this function returns C<-1>
		1253	and sets errno to C<ENOSYS>.
		1254
		1255	Note that the corresponding C<munlockall> is synchronous and is
		1256	documented under L<MISCELLANEOUS FUNCTIONS>.
		1257
		1258	Example: asynchronously lock all current and future pages into memory.
		1259
		1260	aio_mlockall IO::AIO::MCL_FUTURE;
		1261
		1262	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1263
		1264	Queries the extents of the given file (by calling the Linux FIEMAP ioctl,
		1265	see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the
		1266	C<ioctl> is not available on your OS, then this rquiest will fail with
		1267	C<ENOSYS>.
		1268
		1269	C<$start> is the starting offset to query extents for, C<$length> is the
		1270	size of the range to query - if it is C<undef>, then the whole file will
		1271	be queried.
		1272
		1273	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1274	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1275	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1276	the data portion.
		1277
		1278	C<$count> is the maximum number of extent records to return. If it is
		1279	C<undef>, then IO::AIO queries all extents of the file. As a very special
		1280	case, if it is C<0>, then the callback receives the number of extents
		1281	instead of the extents themselves.
		1282
		1283	If an error occurs, the callback receives no arguments. The special
		1284	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1285
		1286	Otherwise, the callback receives an array reference with extent
		1287	structures. Each extent structure is an array reference itself, with the
		1288	following members:
		1289
		1290	[$logical, $physical, $length, $flags]
		1291
		1292	Flags is any combination of the following flag values (typically either C<0>
		1293	or C<IO::AIO::FIEMAP_EXTENT_LAST>):
		1294
		1295	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1296	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1297	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1298	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1299	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1300	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1301
913	=item aio_group $callback->(...)	1302	=item aio_group $callback->(...)
914		1303
915	This is a very special aio request: Instead of doing something, it is a	1304	This is a very special aio request: Instead of doing something, it is a
916	container for other aio requests, which is useful if you want to bundle	1305	container for other aio requests, which is useful if you want to bundle
917	many requests into a single, composite, request with a definite callback	1306	many requests into a single, composite, request with a definite callback
…		…
954	immense (it blocks a thread for a long time) so do not use this function	1343	immense (it blocks a thread for a long time) so do not use this function
955	except to put your application under artificial I/O pressure.	1344	except to put your application under artificial I/O pressure.
956		1345
957	=back	1346	=back
958		1347
		1348
		1349	=head2 IO::AIO::WD - multiple working directories
		1350
		1351	Your process only has one current working directory, which is used by all
		1352	threads. This makes it hard to use relative paths (some other component
		1353	could call C<chdir> at any time, and it is hard to control when the path
		1354	will be used by IO::AIO).
		1355
		1356	One solution for this is to always use absolute paths. This usually works,
		1357	but can be quite slow (the kernel has to walk the whole path on every
		1358	access), and can also be a hassle to implement.
		1359
		1360	Newer POSIX systems have a number of functions (openat, fdopendir,
		1361	futimensat and so on) that make it possible to specify working directories
		1362	per operation.
		1363
		1364	For portability, and because the clowns who "designed", or shall I write,
		1365	perpetrated this new interface were obviously half-drunk, this abstraction
		1366	cannot be perfect, though.
		1367
		1368	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1369	object. This object stores the canonicalised, absolute version of the
		1370	path, and on systems that allow it, also a directory file descriptor.
		1371
		1372	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1373	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1374	object and a pathname instead (or the IO::AIO::WD object alone, which
		1375	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1376	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1377	to that IO::AIO::WD object.
		1378
		1379	For example, to get a wd object for F</etc> and then stat F<passwd>
		1380	inside, you would write:
		1381
		1382	aio_wd "/etc", sub {
		1383	my $etcdir = shift;
		1384
		1385	# although $etcdir can be undef on error, there is generally no reason
		1386	# to check for errors here, as aio_stat will fail with ENOENT
		1387	# when $etcdir is undef.
		1388
		1389	aio_stat [$etcdir, "passwd"], sub {
		1390	# yay
		1391	};
		1392	};
		1393
		1394	That C<aio_wd> is a request and not a normal function shows that creating
		1395	an IO::AIO::WD object is itself a potentially blocking operation, which is
		1396	why it is done asynchronously.
		1397
		1398	To stat the directory obtained with C<aio_wd> above, one could write
		1399	either of the following three request calls:
		1400
		1401	aio_lstat "/etc" , sub { ... # pathname as normal string
		1402	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1403	aio_lstat $wd , sub { ... # shorthand for the previous
		1404
		1405	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1406	object and the pathname string, so you could write the following without
		1407	causing any issues due to C<$path> getting reused:
		1408
		1409	my $path = [$wd, undef];
		1410
		1411	for my $name (qw(abc def ghi)) {
		1412	$path->[1] = $name;
		1413	aio_stat $path, sub {
		1414	# ...
		1415	};
		1416	}
		1417
		1418	There are some caveats: when directories get renamed (or deleted), the
		1419	pathname string doesn't change, so will point to the new directory (or
		1420	nowhere at all), while the directory fd, if available on the system,
		1421	will still point to the original directory. Most functions accepting a
		1422	pathname will use the directory fd on newer systems, and the string on
		1423	older systems. Some functions (such as realpath) will always rely on the
		1424	string form of the pathname.
		1425
		1426	So this fucntionality is mainly useful to get some protection against
		1427	C<chdir>, to easily get an absolute path out of a relative path for future
		1428	reference, and to speed up doing many operations in the same directory
		1429	(e.g. when stat'ing all files in a directory).
		1430
		1431	The following functions implement this working directory abstraction:
		1432
		1433	=over 4
		1434
		1435	=item aio_wd $pathname, $callback->($wd)
		1436
		1437	Asynchonously canonicalise the given pathname and convert it to an
		1438	IO::AIO::WD object representing it. If possible and supported on the
		1439	system, also open a directory fd to speed up pathname resolution relative
		1440	to this working directory.
		1441
		1442	If something goes wrong, then C<undef> is passwd to the callback instead
		1443	of a working directory object and C<$!> is set appropriately. Since
		1444	passing C<undef> as working directory component of a pathname fails the
		1445	request with C<ENOENT>, there is often no need for error checking in the
		1446	C<aio_wd> callback, as future requests using the value will fail in the
		1447	expected way.
		1448
		1449	If this call isn't available because your OS lacks it or it couldn't be
		1450	detected, it will be emulated by calling C<fsync> instead.
		1451
		1452	=item IO::AIO::CWD
		1453
		1454	This is a compiletime constant (object) that represents the process
		1455	current working directory.
		1456
		1457	Specifying this object as working directory object for a pathname is as
		1458	if the pathname would be specified directly, without a directory object,
		1459	e.g., these calls are functionally identical:
		1460
		1461	aio_stat "somefile", sub { ... };
		1462	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1463
		1464	=back
		1465
		1466
959	=head2 IO::AIO::REQ CLASS	1467	=head2 IO::AIO::REQ CLASS
960		1468
961	All non-aggregate C<aio_*> functions return an object of this class when	1469	All non-aggregate C<aio_*> functions return an object of this class when
962	called in non-void context.	1470	called in non-void context.
963		1471
…		…
966	=item cancel $req	1474	=item cancel $req
967		1475
968	Cancels the request, if possible. Has the effect of skipping execution	1476	Cancels the request, if possible. Has the effect of skipping execution
969	when entering the B<execute> state and skipping calling the callback when	1477	when entering the B<execute> state and skipping calling the callback when
970	entering the the B<result> state, but will leave the request otherwise	1478	entering the the B<result> state, but will leave the request otherwise
971	untouched. That means that requests that currently execute will not be	1479	untouched (with the exception of readdir). That means that requests that
972	stopped and resources held by the request will not be freed prematurely.	1480	currently execute will not be stopped and resources held by the request
		1481	will not be freed prematurely.
973		1482
974	=item cb $req $callback->(...)	1483	=item cb $req $callback->(...)
975		1484
976	Replace (or simply set) the callback registered to the request.	1485	Replace (or simply set) the callback registered to the request.
977		1486
…		…
1051	=item $grp->cancel_subs	1560	=item $grp->cancel_subs
1052		1561
1053	Cancel all subrequests and clears any feeder, but not the group request	1562	Cancel all subrequests and clears any feeder, but not the group request
1054	itself. Useful when you queued a lot of events but got a result early.	1563	itself. Useful when you queued a lot of events but got a result early.
1055		1564
		1565	The group request will finish normally (you cannot add requests to the
		1566	group).
		1567
1056	=item $grp->result (...)	1568	=item $grp->result (...)
1057		1569
1058	Set the result value(s) that will be passed to the group callback when all	1570	Set the result value(s) that will be passed to the group callback when all
1059	subrequests have finished and set the groups errno to the current value	1571	subrequests have finished and set the groups errno to the current value
1060	of errno (just like calling C<errno> without an error number). By default,	1572	of errno (just like calling C<errno> without an error number). By default,
…		…
1076		1588
1077	Sets a feeder/generator on this group: every group can have an attached	1589	Sets a feeder/generator on this group: every group can have an attached
1078	generator that generates requests if idle. The idea behind this is that,	1590	generator that generates requests if idle. The idea behind this is that,
1079	although you could just queue as many requests as you want in a group,	1591	although you could just queue as many requests as you want in a group,
1080	this might starve other requests for a potentially long time. For example,	1592	this might starve other requests for a potentially long time. For example,
1081	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1593	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1082	delaying any later requests for a long time.	1594	requests, delaying any later requests for a long time.
1083		1595
1084	To avoid this, and allow incremental generation of requests, you can	1596	To avoid this, and allow incremental generation of requests, you can
1085	instead a group and set a feeder on it that generates those requests. The	1597	instead a group and set a feeder on it that generates those requests. The
1086	feed callback will be called whenever there are few enough (see C<limit>,	1598	feed callback will be called whenever there are few enough (see C<limit>,
1087	below) requests active in the group itself and is expected to queue more	1599	below) requests active in the group itself and is expected to queue more
…		…
1128	=over 4	1640	=over 4
1129		1641
1130	=item $fileno = IO::AIO::poll_fileno	1642	=item $fileno = IO::AIO::poll_fileno
1131		1643
1132	Return the I<request result pipe file descriptor>. This filehandle must be	1644	Return the I<request result pipe file descriptor>. This filehandle must be
1133	polled for reading by some mechanism outside this module (e.g. Event or	1645	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1134	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1646	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1135	to call C<poll_cb> to check the results.	1647	you have to call C<poll_cb> to check the results.
1136		1648
1137	See C<poll_cb> for an example.	1649	See C<poll_cb> for an example.
1138		1650
1139	=item IO::AIO::poll_cb	1651	=item IO::AIO::poll_cb
1140		1652
1141	Process some outstanding events on the result pipe. You have to call this	1653	Process some outstanding events on the result pipe. You have to call
1142	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1654	this regularly. Returns C<0> if all events could be processed (or there
1143	returned earlier for whatever reason. Returns immediately when no events	1655	were no events to process), or C<-1> if it returned earlier for whatever
1144	are outstanding. The amount of events processed depends on the settings of	1656	reason. Returns immediately when no events are outstanding. The amount of
1145	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1657	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1658	C<IO::AIO::max_poll_time>.
1146		1659
1147	If not all requests were processed for whatever reason, the filehandle	1660	If not all requests were processed for whatever reason, the filehandle
1148	will still be ready when C<poll_cb> returns, so normally you don't have to	1661	will still be ready when C<poll_cb> returns, so normally you don't have to
1149	do anything special to have it called later.	1662	do anything special to have it called later.
1150		1663
		1664	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1665	ready, it can be beneficial to call this function from loops which submit
		1666	a lot of requests, to make sure the results get processed when they become
		1667	available and not just when the loop is finished and the event loop takes
		1668	over again. This function returns very fast when there are no outstanding
		1669	requests.
		1670
1151	Example: Install an Event watcher that automatically calls	1671	Example: Install an Event watcher that automatically calls
1152	IO::AIO::poll_cb with high priority:	1672	IO::AIO::poll_cb with high priority (more examples can be found in the
		1673	SYNOPSIS section, at the top of this document):
1153		1674
1154	Event->io (fd => IO::AIO::poll_fileno,	1675	Event->io (fd => IO::AIO::poll_fileno,
1155	poll => 'r', async => 1,	1676	poll => 'r', async => 1,
1156	cb => \&IO::AIO::poll_cb);	1677	cb => \&IO::AIO::poll_cb);
		1678
		1679	=item IO::AIO::poll_wait
		1680
		1681	If there are any outstanding requests and none of them in the result
		1682	phase, wait till the result filehandle becomes ready for reading (simply
		1683	does a C<select> on the filehandle. This is useful if you want to
		1684	synchronously wait for some requests to finish).
		1685
		1686	See C<nreqs> for an example.
		1687
		1688	=item IO::AIO::poll
		1689
		1690	Waits until some requests have been handled.
		1691
		1692	Returns the number of requests processed, but is otherwise strictly
		1693	equivalent to:
		1694
		1695	IO::AIO::poll_wait, IO::AIO::poll_cb
		1696
		1697	=item IO::AIO::flush
		1698
		1699	Wait till all outstanding AIO requests have been handled.
		1700
		1701	Strictly equivalent to:
		1702
		1703	IO::AIO::poll_wait, IO::AIO::poll_cb
		1704	while IO::AIO::nreqs;
1157		1705
1158	=item IO::AIO::max_poll_reqs $nreqs	1706	=item IO::AIO::max_poll_reqs $nreqs
1159		1707
1160	=item IO::AIO::max_poll_time $seconds	1708	=item IO::AIO::max_poll_time $seconds
1161		1709
…		…
1186	# use a low priority so other tasks have priority	1734	# use a low priority so other tasks have priority
1187	Event->io (fd => IO::AIO::poll_fileno,	1735	Event->io (fd => IO::AIO::poll_fileno,
1188	poll => 'r', nice => 1,	1736	poll => 'r', nice => 1,
1189	cb => &IO::AIO::poll_cb);	1737	cb => &IO::AIO::poll_cb);
1190		1738
1191	=item IO::AIO::poll_wait
1192
1193	If there are any outstanding requests and none of them in the result
1194	phase, wait till the result filehandle becomes ready for reading (simply
1195	does a C<select> on the filehandle. This is useful if you want to
1196	synchronously wait for some requests to finish).
1197
1198	See C<nreqs> for an example.
1199
1200	=item IO::AIO::poll
1201
1202	Waits until some requests have been handled.
1203
1204	Returns the number of requests processed, but is otherwise strictly
1205	equivalent to:
1206
1207	IO::AIO::poll_wait, IO::AIO::poll_cb
1208
1209	=item IO::AIO::flush
1210
1211	Wait till all outstanding AIO requests have been handled.
1212
1213	Strictly equivalent to:
1214
1215	IO::AIO::poll_wait, IO::AIO::poll_cb
1216	while IO::AIO::nreqs;
1217
1218	=back	1739	=back
1219		1740
1220	=head3 CONTROLLING THE NUMBER OF THREADS	1741	=head3 CONTROLLING THE NUMBER OF THREADS
1221		1742
1222	=over	1743	=over
…		…
1255		1776
1256	Under normal circumstances you don't need to call this function.	1777	Under normal circumstances you don't need to call this function.
1257		1778
1258	=item IO::AIO::max_idle $nthreads	1779	=item IO::AIO::max_idle $nthreads
1259		1780
1260	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1781	Limit the number of threads (default: 4) that are allowed to idle
1261	threads that did not get a request to process within 10 seconds). That	1782	(i.e., threads that did not get a request to process within the idle
1262	means if a thread becomes idle while C<$nthreads> other threads are also	1783	timeout (default: 10 seconds). That means if a thread becomes idle while
1263	idle, it will free its resources and exit.	1784	C<$nthreads> other threads are also idle, it will free its resources and
		1785	exit.
1264		1786
1265	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1787	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1266	to allow for extremely high load situations, but want to free resources	1788	to allow for extremely high load situations, but want to free resources
1267	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1789	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1268		1790
1269	The default is probably ok in most situations, especially if thread	1791	The default is probably ok in most situations, especially if thread
1270	creation is fast. If thread creation is very slow on your system you might	1792	creation is fast. If thread creation is very slow on your system you might
1271	want to use larger values.	1793	want to use larger values.
1272		1794
		1795	=item IO::AIO::idle_timeout $seconds
		1796
		1797	Sets the minimum idle timeout (default 10) after which worker threads are
		1798	allowed to exit. SEe C<IO::AIO::max_idle>.
		1799
1273	=item IO::AIO::max_outstanding $maxreqs	1800	=item IO::AIO::max_outstanding $maxreqs
		1801
		1802	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1803	you do queue up more than this number of requests, the next call to
		1804	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1805	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1806	longer exceeded.
		1807
		1808	In other words, this setting does not enforce a queue limit, but can be
		1809	used to make poll functions block if the limit is exceeded.
1274		1810
1275	This is a very bad function to use in interactive programs because it	1811	This is a very bad function to use in interactive programs because it
1276	blocks, and a bad way to reduce concurrency because it is inexact: Better	1812	blocks, and a bad way to reduce concurrency because it is inexact: Better
1277	use an C<aio_group> together with a feed callback.	1813	use an C<aio_group> together with a feed callback.
1278		1814
1279	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1815	It's main use is in scripts without an event loop - when you want to stat
1280	do queue up more than this number of requests, the next call to the	1816	a lot of files, you can write somehting like this:
1281	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1282	function will block until the limit is no longer exceeded.
1283		1817
1284	The default value is very large, so there is no practical limit on the	1818	IO::AIO::max_outstanding 32;
1285	number of outstanding requests.
1286		1819
1287	You can still queue as many requests as you want. Therefore,	1820	for my $path (...) {
1288	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1821	aio_stat $path , ...;
1289	as a stop gap to shield against fatal memory overflow (with large values).	1822	IO::AIO::poll_cb;
		1823	}
		1824
		1825	IO::AIO::flush;
		1826
		1827	The call to C<poll_cb> inside the loop will normally return instantly, but
		1828	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1829	some requests have been handled. This keeps the loop from pushing a large
		1830	number of C<aio_stat> requests onto the queue.
		1831
		1832	The default value for C<max_outstanding> is very large, so there is no
		1833	practical limit on the number of outstanding requests.
1290		1834
1291	=back	1835	=back
1292		1836
1293	=head3 STATISTICAL INFORMATION	1837	=head3 STATISTICAL INFORMATION
1294		1838
…		…
1314	Returns the number of requests currently in the pending state (executed,	1858	Returns the number of requests currently in the pending state (executed,
1315	but not yet processed by poll_cb).	1859	but not yet processed by poll_cb).
1316		1860
1317	=back	1861	=back
1318		1862
		1863	=head3 MISCELLANEOUS FUNCTIONS
		1864
		1865	IO::AIO implements some functions that might be useful, but are not
		1866	asynchronous.
		1867
		1868	=over 4
		1869
		1870	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1871
		1872	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1873	but is blocking (this makes most sense if you know the input data is
		1874	likely cached already and the output filehandle is set to non-blocking
		1875	operations).
		1876
		1877	Returns the number of bytes copied, or C<-1> on error.
		1878
		1879	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1880
		1881	Simply calls the C<posix_fadvise> function (see its
		1882	manpage for details). The following advice constants are
		1883	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1884	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1885	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1886
		1887	On systems that do not implement C<posix_fadvise>, this function returns
		1888	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1889
		1890	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1891
		1892	Simply calls the C<posix_madvise> function (see its
		1893	manpage for details). The following advice constants are
		1894	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1895	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1896
		1897	On systems that do not implement C<posix_madvise>, this function returns
		1898	ENOSYS, otherwise the return value of C<posix_madvise>.
		1899
		1900	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1901
		1902	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1903	$scalar (see its manpage for details). The following protect
		1904	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1905	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1906
		1907	On systems that do not implement C<mprotect>, this function returns
		1908	ENOSYS, otherwise the return value of C<mprotect>.
		1909
		1910	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1911
		1912	Memory-maps a file (or anonymous memory range) and attaches it to the
		1913	given C<$scalar>, which will act like a string scalar. Returns true on
		1914	success, and false otherwise.
		1915
		1916	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1917	change the string length, and most read-only operations such as copying it
		1918	or searching it with regexes and so on.
		1919
		1920	Anything else is unsafe and will, at best, result in memory leaks.
		1921
		1922	The memory map associated with the C<$scalar> is automatically removed
		1923	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1924	C<IO::AIO::munmap> functions are called.
		1925
		1926	This calls the C<mmap>(2) function internally. See your system's manual
		1927	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1928
		1929	The C<$length> must be larger than zero and smaller than the actual
		1930	filesize.
		1931
		1932	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1933	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1934
		1935	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1936	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1937	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1938	(which is set to C<MAP_ANON> if your system only provides this
		1939	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1940	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1941	C<IO::AIO::MAP_NONBLOCK>
		1942
		1943	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1944
		1945	C<$offset> is the offset from the start of the file - it generally must be
		1946	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1947
		1948	Example:
		1949
		1950	use Digest::MD5;
		1951	use IO::AIO;
		1952
		1953	open my $fh, "<verybigfile"
		1954	or die "$!";
		1955
		1956	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1957	or die "verybigfile: $!";
		1958
		1959	my $fast_md5 = md5 $data;
		1960
		1961	=item IO::AIO::munmap $scalar
		1962
		1963	Removes a previous mmap and undefines the C<$scalar>.
		1964
		1965	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1966
		1967	Calls the C<munlock> function, undoing the effects of a previous
		1968	C<aio_mlock> call (see its description for details).
		1969
		1970	=item IO::AIO::munlockall
		1971
		1972	Calls the C<munlockall> function.
		1973
		1974	On systems that do not implement C<munlockall>, this function returns
		1975	ENOSYS, otherwise the return value of C<munlockall>.
		1976
		1977	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		1978
		1979	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		1980	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		1981	should be the file offset.
		1982
		1983	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		1984	silently corrupt the data in this case.
		1985
		1986	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		1987	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		1988	C<IO::AIO::SPLICE_F_GIFT>.
		1989
		1990	See the C<splice(2)> manpage for details.
		1991
		1992	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		1993
		1994	Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the
		1995	description for C<IO::AIO::splice> above for details.
		1996
		1997	=back
		1998
1319	=cut	1999	=cut
1320		2000
1321	min_parallel 8;	2001	min_parallel 8;
1322		2002
1323	END { flush }	2003	END { flush }
1324		2004
1325	1;	2005	1;
1326		2006
		2007	=head1 EVENT LOOP INTEGRATION
		2008
		2009	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2010	automatically into many event loops:
		2011
		2012	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2013	use AnyEvent::AIO;
		2014
		2015	You can also integrate IO::AIO manually into many event loops, here are
		2016	some examples of how to do this:
		2017
		2018	# EV integration
		2019	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2020
		2021	# Event integration
		2022	Event->io (fd => IO::AIO::poll_fileno,
		2023	poll => 'r',
		2024	cb => \&IO::AIO::poll_cb);
		2025
		2026	# Glib/Gtk2 integration
		2027	add_watch Glib::IO IO::AIO::poll_fileno,
		2028	in => sub { IO::AIO::poll_cb; 1 };
		2029
		2030	# Tk integration
		2031	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2032	readable => \&IO::AIO::poll_cb);
		2033
		2034	# Danga::Socket integration
		2035	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2036	\&IO::AIO::poll_cb);
		2037
1327	=head2 FORK BEHAVIOUR	2038	=head2 FORK BEHAVIOUR
1328		2039
1329	This module should do "the right thing" when the process using it forks:	2040	Usage of pthreads in a program changes the semantics of fork
		2041	considerably. Specifically, only async-safe functions can be called after
		2042	fork. Perl doesn't know about this, so in general, you cannot call fork
		2043	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2044	pthreads, so this applies, but many other extensions and (for inexplicable
		2045	reasons) perl itself often is linked against pthreads, so this limitation
		2046	applies to quite a lot of perls.
1330		2047
1331	Before the fork, IO::AIO enters a quiescent state where no requests	2048	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1332	can be added in other threads and no results will be processed. After	2049	only works in the process that loaded it. Forking is fully supported, but
1333	the fork the parent simply leaves the quiescent state and continues	2050	using IO::AIO in the child is not.
1334	request/result processing, while the child frees the request/result queue
1335	(so that the requests started before the fork will only be handled in the
1336	parent). Threads will be started on demand until the limit set in the
1337	parent process has been reached again.
1338		2051
1339	In short: the parent will, after a short pause, continue as if fork had	2052	You might get around by not I<using> IO::AIO before (or after)
1340	not been called, while the child will act as if IO::AIO has not been used	2053	forking. You could also try to call the L<IO::AIO::reinit> function in the
1341	yet.	2054	child:
		2055
		2056	=over 4
		2057
		2058	=item IO::AIO::reinit
		2059
		2060	Abandons all current requests and I/O threads and simply reinitialises all
		2061	data structures. This is not an operation supported by any standards, but
		2062	happens to work on GNU/Linux and some newer BSD systems.
		2063
		2064	The only reasonable use for this function is to call it after forking, if
		2065	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2066	the process will result in undefined behaviour. Calling it at any time
		2067	will also result in any undefined (by POSIX) behaviour.
		2068
		2069	=back
1342		2070
1343	=head2 MEMORY USAGE	2071	=head2 MEMORY USAGE
1344		2072
1345	Per-request usage:	2073	Per-request usage:
1346		2074

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