ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.141 by root, Wed Oct 22 16:30:49 2008 UTC vs.
Revision 1.223 by root, Fri Apr 6 22:51:02 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 = '3.16';	173	our $VERSION = '4.13';
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
		178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
203	aio_fdatasync aio_pathsync aio_readahead	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);
		194
		195	push @AIO_REQ, qw(aio_busy); # not exported
213		196
214	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
215		198
216	require XSLoader;	199	require XSLoader;
217	XSLoader::load ("IO::AIO", $VERSION);	200	XSLoader::load ("IO::AIO", $VERSION);
218	}	201	}
219		202
220	=head1 FUNCTIONS	203	=head1 FUNCTIONS
221		204
222	=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::madvise $scalar, $offset, $length, $advice
		278	IO::AIO::mprotect $scalar, $offset, $length, $protect
		279	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		280	IO::AIO::munlockall
		281
		282	=head2 API NOTES
223		283
224	All the C<aio_*> calls are more or less thin wrappers around the syscall	284	All the C<aio_*> calls are more or less thin wrappers around the syscall
225	with the same name (sans C<aio_>). The arguments are similar or identical,	285	with the same name (sans C<aio_>). The arguments are similar or identical,
226	and they all accept an additional (and optional) C<$callback> argument	286	and they all accept an additional (and optional) C<$callback> argument
227	which must be a code reference. This code reference will get called with	287	which must be a code reference. This code reference will be called after
228	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	288	the syscall has been executed in an asynchronous fashion. The results
229	perl, which usually delivers "false") as its sole argument after the given	289	of the request will be passed as arguments to the callback (and, if an
230	syscall has been executed asynchronously.	290	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		291	most syscalls return C<-1> on error, unlike perl, which usually delivers
		292	"false").
		293
		294	Some requests (such as C<aio_readdir>) pass the actual results and
		295	communicate failures by passing C<undef>.
231		296
232	All functions expecting a filehandle keep a copy of the filehandle	297	All functions expecting a filehandle keep a copy of the filehandle
233	internally until the request has finished.	298	internally until the request has finished.
234		299
235	All functions return request objects of type L<IO::AIO::REQ> that allow	300	All functions return request objects of type L<IO::AIO::REQ> that allow
236	further manipulation of those requests while they are in-flight.	301	further manipulation of those requests while they are in-flight.
237		302
238	The pathnames you pass to these routines I<must> be absolute and	303	The pathnames you pass to these routines I<should> be absolute. The
239	encoded as octets. The reason for the former is that at the time the	304	reason for this is that at the time the request is being executed, the
240	request is being executed, the current working directory could have	305	current working directory could have changed. Alternatively, you can
241	changed. Alternatively, you can make sure that you never change the	306	make sure that you never change the current working directory anywhere
242	current working directory anywhere in the program and then use relative	307	in the program and then use relative paths. You can also take advantage
243	paths.	308	of IO::AIOs working directory abstraction, that lets you specify paths
		309	relative to some previously-opened "working directory object" - see the
		310	description of the C<IO::AIO::WD> class later in this document.
244		311
245	To encode pathnames as octets, either make sure you either: a) always pass	312	To encode pathnames as octets, either make sure you either: a) always pass
246	in filenames you got from outside (command line, readdir etc.) without	313	in filenames you got from outside (command line, readdir etc.) without
247	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	314	tinkering, b) are in your native filesystem encoding, c) use the Encode
248	your pathnames to the locale (or other) encoding in effect in the user	315	module and encode your pathnames to the locale (or other) encoding in
249	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	316	effect in the user environment, d) use Glib::filename_from_unicode on
250	use something else to ensure your scalar has the correct contents.	317	unicode filenames or e) use something else to ensure your scalar has the
		318	correct contents.
251		319
252	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	320	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
253	handles correctly whether it is set or not.	321	handles correctly whether it is set or not.
		322
		323	=head2 AIO REQUEST FUNCTIONS
254		324
255	=over 4	325	=over 4
256		326
257	=item $prev_pri = aioreq_pri [$pri]	327	=item $prev_pri = aioreq_pri [$pri]
258		328
…		…
305	by the umask in effect then the request is being executed, so better never	375	by the umask in effect then the request is being executed, so better never
306	change the umask.	376	change the umask.
307		377
308	Example:	378	Example:
309		379
310	aio_open "/etc/passwd", O_RDONLY, 0, sub {	380	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
311	if ($_[0]) {	381	if ($_[0]) {
312	print "open successful, fh is $_[0]\n";	382	print "open successful, fh is $_[0]\n";
313	...	383	...
314	} else {	384	} else {
315	die "open failed: $!\n";	385	die "open failed: $!\n";
316	}	386	}
317	};	387	};
318		388
		389	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		390	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		391	following POSIX and non-POSIX constants are available (missing ones on
		392	your system are, as usual, C<0>):
		393
		394	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		395	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		396	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		397
319		398
320	=item aio_close $fh, $callback->($status)	399	=item aio_close $fh, $callback->($status)
321		400
322	Asynchronously close a file and call the callback with the result	401	Asynchronously close a file and call the callback with the result
323	code.	402	code.
…		…
332	Or in other words: the file descriptor will be closed, but it will not be	411	Or in other words: the file descriptor will be closed, but it will not be
333	free for reuse until the perl filehandle is closed.	412	free for reuse until the perl filehandle is closed.
334		413
335	=cut	414	=cut
336		415
		416	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		417
		418	Seeks the filehandle to the new C<$offset>, similarly to perl's
		419	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		420	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		421	C<IO::AIO::SEEK_END>).
		422
		423	The resulting absolute offset will be passed to the callback, or C<-1> in
		424	case of an error.
		425
		426	In theory, the C<$whence> constants could be different than the
		427	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		428	so don't panic.
		429
337	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	430	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
338		431
339	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	432	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		433
341	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>	434	Reads or writes C<$length> bytes from or to the specified C<$fh> and
342	into the scalar given by C<$data> and offset C<$dataoffset> and calls the	435	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
343	callback without the actual number of bytes read (or -1 on error, just	436	and calls the callback without the actual number of bytes read (or -1 on
344	like the syscall).	437	error, just like the syscall).
		438
		439	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		440	offset plus the actual number of bytes read.
345		441
346	If C<$offset> is undefined, then the current file descriptor offset will	442	If C<$offset> is undefined, then the current file descriptor offset will
347	be used (and updated), otherwise the file descriptor offset will not be	443	be used (and updated), otherwise the file descriptor offset will not be
348	changed by these calls.	444	changed by these calls.
349		445
350	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.	446	If C<$length> is undefined in C<aio_write>, use the remaining length of
		447	C<$data>.
351		448
352	If C<$dataoffset> is less than zero, it will be counted from the end of	449	If C<$dataoffset> is less than zero, it will be counted from the end of
353	C<$data>.	450	C<$data>.
354		451
355	The C<$data> scalar I<MUST NOT> be modified in any way while the request	452	The C<$data> scalar I<MUST NOT> be modified in any way while the request
…		…
369		466
370	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	467	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
371	reading at byte offset C<$in_offset>, and starts writing at the current	468	reading at byte offset C<$in_offset>, and starts writing at the current
372	file offset of C<$out_fh>. Because of that, it is not safe to issue more	469	file offset of C<$out_fh>. Because of that, it is not safe to issue more
373	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	470	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
374	other.	471	other. The same C<$in_fh> works fine though, as this function does not
		472	move or use the file offset of C<$in_fh>.
375		473
		474	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		475	are written, and there is no way to find out how many more bytes have been
		476	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		477	number of bytes written to C<$out_fh>. Only if the result value equals
		478	C<$length> one can assume that C<$length> bytes have been read.
		479
		480	Unlike with other C<aio_> functions, it makes a lot of sense to use
		481	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		482	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		483	the socket I/O will be non-blocking. Note, however, that you can run
		484	into a trap where C<aio_sendfile> reads some data with readahead, then
		485	fails to write all data, and when the socket is ready the next time, the
		486	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		487	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		488	resource usage.
		489
376	This call tries to make use of a native C<sendfile> syscall to provide	490	This call tries to make use of a native C<sendfile>-like syscall to
377	zero-copy operation. For this to work, C<$out_fh> should refer to a	491	provide zero-copy operation. For this to work, C<$out_fh> should refer to
378	socket, and C<$in_fh> should refer to mmap'able file.	492	a socket, and C<$in_fh> should refer to an mmap'able file.
379		493
380	If the native sendfile call fails or is not implemented, it will be	494	If a native sendfile cannot be found or it fails with C<ENOSYS>,
381	emulated, so you can call C<aio_sendfile> on any type of filehandle	495	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		496	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
382	regardless of the limitations of the operating system.	497	type of filehandle regardless of the limitations of the operating system.
383		498
384	Please note, however, that C<aio_sendfile> can read more bytes from	499	As native sendfile syscalls (as practically any non-POSIX interface hacked
385	C<$in_fh> than are written, and there is no way to find out how many	500	together in a hurry to improve benchmark numbers) tend to be rather buggy
386	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	501	on many systems, this implementation tries to work around some known bugs
387	provides the number of bytes written to C<$out_fh>. Only if the result	502	in Linux and FreeBSD kernels (probably others, too), but that might fail,
388	value equals C<$length> one can assume that C<$length> bytes have been	503	so you really really should check the return value of C<aio_sendfile> -
389	read.	504	fewre bytes than expected might have been transferred.
390		505
391		506
392	=item aio_readahead $fh,$offset,$length, $callback->($retval)	507	=item aio_readahead $fh,$offset,$length, $callback->($retval)
393		508
394	C<aio_readahead> populates the page cache with data from a file so that	509	C<aio_readahead> populates the page cache with data from a file so that
…		…
417		532
418	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	533	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
419	error when stat'ing a large file, the results will be silently truncated	534	error when stat'ing a large file, the results will be silently truncated
420	unless perl itself is compiled with large file support.	535	unless perl itself is compiled with large file support.
421		536
		537	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		538	following constants and functions (if not implemented, the constants will
		539	be C<0> and the functions will either C<croak> or fall back on traditional
		540	behaviour).
		541
		542	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		543	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		544	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		545
422	Example: Print the length of F</etc/passwd>:	546	Example: Print the length of F</etc/passwd>:
423		547
424	aio_stat "/etc/passwd", sub {	548	aio_stat "/etc/passwd", sub {
425	$_[0] and die "stat failed: $!";	549	$_[0] and die "stat failed: $!";
426	print "size is ", -s _, "\n";	550	print "size is ", -s _, "\n";
427	};	551	};
428		552
429		553
		554	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		555
		556	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		557	whether a file handle or path was passed.
		558
		559	On success, the callback is passed a hash reference with the following
		560	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		561	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		562	is passed.
		563
		564	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		565	C<ST_NOSUID>.
		566
		567	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		568	their correct value when available, or to C<0> on systems that do
		569	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		570	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		571	C<ST_NODIRATIME> and C<ST_RELATIME>.
		572
		573	Example: stat C</wd> and dump out the data if successful.
		574
		575	aio_statvfs "/wd", sub {
		576	my $f = $_[0]
		577	or die "statvfs: $!";
		578
		579	use Data::Dumper;
		580	say Dumper $f;
		581	};
		582
		583	# result:
		584	{
		585	bsize => 1024,
		586	bfree => 4333064312,
		587	blocks => 10253828096,
		588	files => 2050765568,
		589	flag => 4096,
		590	favail => 2042092649,
		591	bavail => 4333064312,
		592	ffree => 2042092649,
		593	namemax => 255,
		594	frsize => 1024,
		595	fsid => 1810
		596	}
		597
		598
430	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	599	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
431		600
432	Works like perl's C<utime> function (including the special case of $atime	601	Works like perl's C<utime> function (including the special case of $atime
433	and $mtime being undef). Fractional times are supported if the underlying	602	and $mtime being undef). Fractional times are supported if the underlying
434	syscalls support them.	603	syscalls support them.
…		…
472		641
473	Asynchronously unlink (delete) a file and call the callback with the	642	Asynchronously unlink (delete) a file and call the callback with the
474	result code.	643	result code.
475		644
476		645
477	=item aio_mknod $path, $mode, $dev, $callback->($status)	646	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
478		647
479	[EXPERIMENTAL]	648	[EXPERIMENTAL]
480		649
481	Asynchronously create a device node (or fifo). See mknod(2).	650	Asynchronously create a device node (or fifo). See mknod(2).
482		651
483	The only (POSIX-) portable way of calling this function is:	652	The only (POSIX-) portable way of calling this function is:
484		653
485	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	654	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
486		655
		656	See C<aio_stat> for info about some potentially helpful extra constants
		657	and functions.
487		658
488	=item aio_link $srcpath, $dstpath, $callback->($status)	659	=item aio_link $srcpath, $dstpath, $callback->($status)
489		660
490	Asynchronously create a new link to the existing object at C<$srcpath> at	661	Asynchronously create a new link to the existing object at C<$srcpath> at
491	the path C<$dstpath> and call the callback with the result code.	662	the path C<$dstpath> and call the callback with the result code.
…		…
495		666
496	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	667	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
497	the path C<$dstpath> and call the callback with the result code.	668	the path C<$dstpath> and call the callback with the result code.
498		669
499		670
500	=item aio_readlink $path, $callback->($link)	671	=item aio_readlink $pathname, $callback->($link)
501		672
502	Asynchronously read the symlink specified by C<$path> and pass it to	673	Asynchronously read the symlink specified by C<$path> and pass it to
503	the callback. If an error occurs, nothing or undef gets passed to the	674	the callback. If an error occurs, nothing or undef gets passed to the
504	callback.	675	callback.
505		676
506		677
		678	=item aio_realpath $pathname, $callback->($path)
		679
		680	Asynchronously make the path absolute and resolve any symlinks in
		681	C<$path>. The resulting path only consists of directories (Same as
		682	L<Cwd::realpath>).
		683
		684	This request can be used to get the absolute path of the current working
		685	directory by passing it a path of F<.> (a single dot).
		686
		687
507	=item aio_rename $srcpath, $dstpath, $callback->($status)	688	=item aio_rename $srcpath, $dstpath, $callback->($status)
508		689
509	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	690	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
510	rename(2) and call the callback with the result code.	691	rename(2) and call the callback with the result code.
511		692
…		…
527		708
528	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	709	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
529	directory (i.e. opendir + readdir + closedir). The entries will not be	710	directory (i.e. opendir + readdir + closedir). The entries will not be
530	sorted, and will B<NOT> include the C<.> and C<..> entries.	711	sorted, and will B<NOT> include the C<.> and C<..> entries.
531		712
532	The callback a single argument which is either C<undef> or an array-ref	713	The callback is passed a single argument which is either C<undef> or an
533	with the filenames.	714	array-ref with the filenames.
534		715
535		716
		717	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		718
		719	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		720	tune behaviour and output format. In case of an error, C<$entries> will be
		721	C<undef>.
		722
		723	The flags are a combination of the following constants, ORed together (the
		724	flags will also be passed to the callback, possibly modified):
		725
		726	=over 4
		727
		728	=item IO::AIO::READDIR_DENTS
		729
		730	When this flag is off, then the callback gets an arrayref consisting of
		731	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		732	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		733	entry in more detail.
		734
		735	C<$name> is the name of the entry.
		736
		737	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		738
		739	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		740	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		741	C<IO::AIO::DT_WHT>.
		742
		743	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		744	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		745	scalars are read-only: you can not modify them.
		746
		747	C<$inode> is the inode number (which might not be exact on systems with 64
		748	bit inode numbers and 32 bit perls). This field has unspecified content on
		749	systems that do not deliver the inode information.
		750
		751	=item IO::AIO::READDIR_DIRS_FIRST
		752
		753	When this flag is set, then the names will be returned in an order where
		754	likely directories come first, in optimal stat order. This is useful when
		755	you need to quickly find directories, or you want to find all directories
		756	while avoiding to stat() each entry.
		757
		758	If the system returns type information in readdir, then this is used
		759	to find directories directly. Otherwise, likely directories are names
		760	beginning with ".", or otherwise names with no dots, of which names with
		761	short names are tried first.
		762
		763	=item IO::AIO::READDIR_STAT_ORDER
		764
		765	When this flag is set, then the names will be returned in an order
		766	suitable for stat()'ing each one. That is, when you plan to stat()
		767	all files in the given directory, then the returned order will likely
		768	be fastest.
		769
		770	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		771	the likely dirs come first, resulting in a less optimal stat order.
		772
		773	=item IO::AIO::READDIR_FOUND_UNKNOWN
		774
		775	This flag should not be set when calling C<aio_readdirx>. Instead, it
		776	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		777	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		778	C<$type>'s are known, which can be used to speed up some algorithms.
		779
		780	=back
		781
		782
536	=item aio_load $path, $data, $callback->($status)	783	=item aio_load $pathname, $data, $callback->($status)
537		784
538	This is a composite request that tries to fully load the given file into	785	This is a composite request that tries to fully load the given file into
539	memory. Status is the same as with aio_read.	786	memory. Status is the same as with aio_read.
540		787
541	=cut	788	=cut
…		…
563		810
564	=item aio_copy $srcpath, $dstpath, $callback->($status)	811	=item aio_copy $srcpath, $dstpath, $callback->($status)
565		812
566	Try to copy the I<file> (directories not supported as either source or	813	Try to copy the I<file> (directories not supported as either source or
567	destination) from C<$srcpath> to C<$dstpath> and call the callback with	814	destination) from C<$srcpath> to C<$dstpath> and call the callback with
568	the C<0> (error) or C<-1> ok.	815	a status of C<0> (ok) or C<-1> (error, see C<$!>).
569		816
570	This is a composite request that creates the destination file with	817	This is a composite request that creates the destination file with
571	mode 0200 and copies the contents of the source file into it using	818	mode 0200 and copies the contents of the source file into it using
572	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	819	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
573	uid/gid, in that order.	820	uid/gid, in that order.
…		…
585	my $grp = aio_group $cb;	832	my $grp = aio_group $cb;
586		833
587	aioreq_pri $pri;	834	aioreq_pri $pri;
588	add $grp aio_open $src, O_RDONLY, 0, sub {	835	add $grp aio_open $src, O_RDONLY, 0, sub {
589	if (my $src_fh = $_[0]) {	836	if (my $src_fh = $_[0]) {
590	my @stat = stat $src_fh;	837	my @stat = stat $src_fh; # hmm, might block over nfs?
591		838
592	aioreq_pri $pri;	839	aioreq_pri $pri;
593	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	840	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
594	if (my $dst_fh = $_[0]) {	841	if (my $dst_fh = $_[0]) {
595	aioreq_pri $pri;	842	aioreq_pri $pri;
596	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	843	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
597	if ($_[0] == $stat[7]) {	844	if ($_[0] == $stat[7]) {
598	$grp->result (0);	845	$grp->result (0);
599	close $src_fh;	846	close $src_fh;
600		847
601	# those should not normally block. should. should.	848	my $ch = sub {
602	utime $stat[8], $stat[9], $dst;	849	aioreq_pri $pri;
603	chmod $stat[2] & 07777, $dst_fh;	850	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
604	chown $stat[4], $stat[5], $dst_fh;	851	aioreq_pri $pri;
		852	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		853	aioreq_pri $pri;
		854	add $grp aio_close $dst_fh;
		855	}
		856	};
		857	};
605		858
606	aioreq_pri $pri;	859	aioreq_pri $pri;
607	add $grp aio_close $dst_fh;	860	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		861	if ($_[0] < 0 && $! == ENOSYS) {
		862	aioreq_pri $pri;
		863	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		864	} else {
		865	$ch->();
		866	}
		867	};
608	} else {	868	} else {
609	$grp->result (-1);	869	$grp->result (-1);
610	close $src_fh;	870	close $src_fh;
611	close $dst_fh;	871	close $dst_fh;
612		872
…		…
629		889
630	=item aio_move $srcpath, $dstpath, $callback->($status)	890	=item aio_move $srcpath, $dstpath, $callback->($status)
631		891
632	Try to move the I<file> (directories not supported as either source or	892	Try to move the I<file> (directories not supported as either source or
633	destination) from C<$srcpath> to C<$dstpath> and call the callback with	893	destination) from C<$srcpath> to C<$dstpath> and call the callback with
634	the C<0> (error) or C<-1> ok.	894	a status of C<0> (ok) or C<-1> (error, see C<$!>).
635		895
636	This is a composite request that tries to rename(2) the file first; if	896	This is a composite request that tries to rename(2) the file first; if
637	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	897	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
638	that is successful, unlinks the C<$srcpath>.	898	that is successful, unlinks the C<$srcpath>.
639		899
…		…
650	if ($_[0] && $! == EXDEV) {	910	if ($_[0] && $! == EXDEV) {
651	aioreq_pri $pri;	911	aioreq_pri $pri;
652	add $grp aio_copy $src, $dst, sub {	912	add $grp aio_copy $src, $dst, sub {
653	$grp->result ($_[0]);	913	$grp->result ($_[0]);
654		914
655	if (!$_[0]) {	915	unless ($_[0]) {
656	aioreq_pri $pri;	916	aioreq_pri $pri;
657	add $grp aio_unlink $src;	917	add $grp aio_unlink $src;
658	}	918	}
659	};	919	};
660	} else {	920	} else {
…		…
663	};	923	};
664		924
665	$grp	925	$grp
666	}	926	}
667		927
668	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	928	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
669		929
670	Scans a directory (similar to C<aio_readdir>) but additionally tries to	930	Scans a directory (similar to C<aio_readdir>) but additionally tries to
671	efficiently separate the entries of directory C<$path> into two sets of	931	efficiently separate the entries of directory C<$path> into two sets of
672	names, directories you can recurse into (directories), and ones you cannot	932	names, directories you can recurse into (directories), and ones you cannot
673	recurse into (everything else, including symlinks to directories).	933	recurse into (everything else, including symlinks to directories).
…		…
690		950
691	Implementation notes.	951	Implementation notes.
692		952
693	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	953	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
694		954
		955	If readdir returns file type information, then this is used directly to
		956	find directories.
		957
695	After reading the directory, the modification time, size etc. of the	958	Otherwise, after reading the directory, the modification time, size etc.
696	directory before and after the readdir is checked, and if they match (and	959	of the directory before and after the readdir is checked, and if they
697	isn't the current time), the link count will be used to decide how many	960	match (and isn't the current time), the link count will be used to decide
698	entries are directories (if >= 2). Otherwise, no knowledge of the number	961	how many entries are directories (if >= 2). Otherwise, no knowledge of the
699	of subdirectories will be assumed.	962	number of subdirectories will be assumed.
700		963
701	Then entries will be sorted into likely directories (everything without	964	Then entries will be sorted into likely directories a non-initial dot
702	a non-initial dot currently) and likely non-directories (everything	965	currently) and likely non-directories (see C<aio_readdirx>). Then every
703	else). Then every entry plus an appended C</.> will be C<stat>'ed,	966	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
704	likely directories first. If that succeeds, it assumes that the entry	967	in order of their inode numbers. If that succeeds, it assumes that the
705	is a directory or a symlink to directory (which will be checked	968	entry is a directory or a symlink to directory (which will be checked
706	seperately). This is often faster than stat'ing the entry itself because	969	separately). This is often faster than stat'ing the entry itself because
707	filesystems might detect the type of the entry without reading the inode	970	filesystems might detect the type of the entry without reading the inode
708	data (e.g. ext2fs filetype feature).	971	data (e.g. ext2fs filetype feature), even on systems that cannot return
		972	the filetype information on readdir.
709		973
710	If the known number of directories (link count - 2) has been reached, the	974	If the known number of directories (link count - 2) has been reached, the
711	rest of the entries is assumed to be non-directories.	975	rest of the entries is assumed to be non-directories.
712		976
713	This only works with certainty on POSIX (= UNIX) filesystems, which	977	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
726		990
727	my $grp = aio_group $cb;	991	my $grp = aio_group $cb;
728		992
729	$maxreq = 4 if $maxreq <= 0;	993	$maxreq = 4 if $maxreq <= 0;
730		994
731	# stat once	995	# get a wd object
732	aioreq_pri $pri;	996	aioreq_pri $pri;
733	add $grp aio_stat $path, sub {	997	add $grp aio_wd $path, sub {
		998	$_[0]
734	return $grp->result () if $_[0];	999	or return $grp->result ();
735	my $now = time;
736	my $hash1 = join ":", (stat _)[0,1,3,7,9];
737		1000
738	# read the directory entries	1001	my $wd = [shift, "."];
		1002
		1003	# stat once
739	aioreq_pri $pri;	1004	aioreq_pri $pri;
740	add $grp aio_readdir $path, sub {	1005	add $grp aio_stat $wd, sub {
741	my $entries = shift
742	or return $grp->result ();	1006	return $grp->result () if $_[0];
		1007	my $now = time;
		1008	my $hash1 = join ":", (stat _)[0,1,3,7,9];
743		1009
744	# stat the dir another time	1010	# read the directory entries
745	aioreq_pri $pri;	1011	aioreq_pri $pri;
		1012	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1013	my $entries = shift
		1014	or return $grp->result ();
		1015
		1016	# stat the dir another time
		1017	aioreq_pri $pri;
746	add $grp aio_stat $path, sub {	1018	add $grp aio_stat $wd, sub {
747	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1019	my $hash2 = join ":", (stat _)[0,1,3,7,9];
748		1020
749	my $ndirs;	1021	my $ndirs;
750		1022
751	# take the slow route if anything looks fishy	1023	# take the slow route if anything looks fishy
752	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1024	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
753	$ndirs = -1;	1025	$ndirs = -1;
754	} else {	1026	} else {
755	# if nlink == 2, we are finished	1027	# if nlink == 2, we are finished
756	# on non-posix-fs's, we rely on nlink < 2	1028	# for non-posix-fs's, we rely on nlink < 2
757	$ndirs = (stat _)[3] - 2	1029	$ndirs = (stat _)[3] - 2
758	or return $grp->result ([], $entries);	1030	or return $grp->result ([], $entries);
759	}	1031	}
760		1032
761	# sort into likely dirs and likely nondirs
762	# dirs == files without ".", short entries first
763	$entries = [map $_->[0],
764	sort { $b->[1] cmp $a->[1] }
765	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
766	@$entries];
767
768	my (@dirs, @nondirs);	1033	my (@dirs, @nondirs);
769		1034
770	my $statgrp = add $grp aio_group sub {	1035	my $statgrp = add $grp aio_group sub {
771	$grp->result (\@dirs, \@nondirs);	1036	$grp->result (\@dirs, \@nondirs);
772	};	1037	};
773		1038
774	limit $statgrp $maxreq;	1039	limit $statgrp $maxreq;
775	feed $statgrp sub {	1040	feed $statgrp sub {
776	return unless @$entries;	1041	return unless @$entries;
777	my $entry = pop @$entries;	1042	my $entry = shift @$entries;
778		1043
779	aioreq_pri $pri;	1044	aioreq_pri $pri;
		1045	$wd->[1] = "$entry/.";
780	add $statgrp aio_stat "$path/$entry/.", sub {	1046	add $statgrp aio_stat $wd, sub {
781	if ($_[0] < 0) {	1047	if ($_[0] < 0) {
782	push @nondirs, $entry;	1048	push @nondirs, $entry;
783	} else {	1049	} else {
784	# need to check for real directory	1050	# need to check for real directory
785	aioreq_pri $pri;	1051	aioreq_pri $pri;
		1052	$wd->[1] = $entry;
786	add $statgrp aio_lstat "$path/$entry", sub {	1053	add $statgrp aio_lstat $wd, sub {
787	if (-d _) {	1054	if (-d _) {
788	push @dirs, $entry;	1055	push @dirs, $entry;
789		1056
790	unless (--$ndirs) {	1057	unless (--$ndirs) {
791	push @nondirs, @$entries;	1058	push @nondirs, @$entries;
792	feed $statgrp;	1059	feed $statgrp;
		1060	}
		1061	} else {
		1062	push @nondirs, $entry;
793	}	1063	}
794	} else {
795	push @nondirs, $entry;
796	}	1064	}
797	}	1065	}
798	}	1066	};
799	};	1067	};
800	};	1068	};
801	};	1069	};
802	};	1070	};
803	};	1071	};
804		1072
805	$grp	1073	$grp
806	}	1074	}
807		1075
808	=item aio_rmtree $path, $callback->($status)	1076	=item aio_rmtree $pathname, $callback->($status)
809		1077
810	Delete a directory tree starting (and including) C<$path>, return the	1078	Delete a directory tree starting (and including) C<$path>, return the
811	status of the final C<rmdir> only. This is a composite request that	1079	status of the final C<rmdir> only. This is a composite request that
812	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1080	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
813	everything else.	1081	everything else.
…		…
855	callback with the fdatasync result code.	1123	callback with the fdatasync result code.
856		1124
857	If this call isn't available because your OS lacks it or it couldn't be	1125	If this call isn't available because your OS lacks it or it couldn't be
858	detected, it will be emulated by calling C<fsync> instead.	1126	detected, it will be emulated by calling C<fsync> instead.
859		1127
		1128	=item aio_syncfs $fh, $callback->($status)
		1129
		1130	Asynchronously call the syncfs syscall to sync the filesystem associated
		1131	to the given filehandle and call the callback with the syncfs result
		1132	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1133	errno to C<ENOSYS> nevertheless.
		1134
		1135	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1136
		1137	Sync the data portion of the file specified by C<$offset> and C<$length>
		1138	to disk (but NOT the metadata), by calling the Linux-specific
		1139	sync_file_range call. If sync_file_range is not available or it returns
		1140	ENOSYS, then fdatasync or fsync is being substituted.
		1141
		1142	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1143	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1144	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1145	manpage for details.
		1146
860	=item aio_pathsync $path, $callback->($status)	1147	=item aio_pathsync $pathname, $callback->($status)
861		1148
862	This request tries to open, fsync and close the given path. This is a	1149	This request tries to open, fsync and close the given path. This is a
863	composite request intended to sync directories after directory operations	1150	composite request intended to sync directories after directory operations
864	(E.g. rename). This might not work on all operating systems or have any	1151	(E.g. rename). This might not work on all operating systems or have any
865	specific effect, but usually it makes sure that directory changes get	1152	specific effect, but usually it makes sure that directory changes get
866	written to disc. It works for anything that can be opened for read-only,	1153	written to disc. It works for anything that can be opened for read-only,
867	not just directories.	1154	not just directories.
		1155
		1156	Future versions of this function might fall back to other methods when
		1157	C<fsync> on the directory fails (such as calling C<sync>).
868		1158
869	Passes C<0> when everything went ok, and C<-1> on error.	1159	Passes C<0> when everything went ok, and C<-1> on error.
870		1160
871	=cut	1161	=cut
872		1162
…		…
893	};	1183	};
894		1184
895	$grp	1185	$grp
896	}	1186	}
897		1187
		1188	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1189
		1190	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1191	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1192	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1193	scalar must only be modified in-place while an aio operation is pending on
		1194	it).
		1195
		1196	It calls the C<msync> function of your OS, if available, with the memory
		1197	area starting at C<$offset> in the string and ending C<$length> bytes
		1198	later. If C<$length> is negative, counts from the end, and if C<$length>
		1199	is C<undef>, then it goes till the end of the string. The flags can be
		1200	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1201	C<IO::AIO::MS_SYNC>.
		1202
		1203	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1204
		1205	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1206	scalars.
		1207
		1208	It touches (reads or writes) all memory pages in the specified
		1209	range inside the scalar. All caveats and parameters are the same
		1210	as for C<aio_msync>, above, except for flags, which must be either
		1211	C<0> (which reads all pages and ensures they are instantiated) or
		1212	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1213	writing an octet from it, which dirties the page).
		1214
		1215	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1216
		1217	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1218	scalars.
		1219
		1220	It reads in all the pages of the underlying storage into memory (if any)
		1221	and locks them, so they are not getting swapped/paged out or removed.
		1222
		1223	If C<$length> is undefined, then the scalar will be locked till the end.
		1224
		1225	On systems that do not implement C<mlock>, this function returns C<-1>
		1226	and sets errno to C<ENOSYS>.
		1227
		1228	Note that the corresponding C<munlock> is synchronous and is
		1229	documented under L<MISCELLANEOUS FUNCTIONS>.
		1230
		1231	Example: open a file, mmap and mlock it - both will be undone when
		1232	C<$data> gets destroyed.
		1233
		1234	open my $fh, "<", $path or die "$path: $!";
		1235	my $data;
		1236	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1237	aio_mlock $data; # mlock in background
		1238
		1239	=item aio_mlockall $flags, $callback->($status)
		1240
		1241	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1242	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1243
		1244	On systems that do not implement C<mlockall>, this function returns C<-1>
		1245	and sets errno to C<ENOSYS>.
		1246
		1247	Note that the corresponding C<munlockall> is synchronous and is
		1248	documented under L<MISCELLANEOUS FUNCTIONS>.
		1249
		1250	Example: asynchronously lock all current and future pages into memory.
		1251
		1252	aio_mlockall IO::AIO::MCL_FUTURE;
		1253
		1254	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1255
		1256	Queries the extents of the given file (by calling the Linux FIEMAP ioctl,
		1257	see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the
		1258	C<ioctl> is not available on your OS, then this rquiest will fail with
		1259	C<ENOSYS>.
		1260
		1261	C<$start> is the starting offset to query extents for, C<$length> is the
		1262	size of the range to query - if it is C<undef>, then the whole file will
		1263	be queried.
		1264
		1265	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1266	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1267	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1268	the data portion.
		1269
		1270	C<$count> is the maximum number of extent records to return. If it is
		1271	C<undef>, then IO::AIO queries all extents of the file. As a very special
		1272	case, if it is C<0>, then the callback receives the number of extents
		1273	instead of the extents themselves.
		1274
		1275	If an error occurs, the callback receives no arguments. The special
		1276	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1277
		1278	Otherwise, the callback receives an array reference with extent
		1279	structures. Each extent structure is an array reference itself, with the
		1280	following members:
		1281
		1282	[$logical, $physical, $length, $flags]
		1283
		1284	Flags is any combination of the following flag values (typically either C<0>
		1285	or C<IO::AIO::FIEMAP_EXTENT_LAST>):
		1286
		1287	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1288	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1289	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1290	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1291	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1292	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1293
898	=item aio_group $callback->(...)	1294	=item aio_group $callback->(...)
899		1295
900	This is a very special aio request: Instead of doing something, it is a	1296	This is a very special aio request: Instead of doing something, it is a
901	container for other aio requests, which is useful if you want to bundle	1297	container for other aio requests, which is useful if you want to bundle
902	many requests into a single, composite, request with a definite callback	1298	many requests into a single, composite, request with a definite callback
…		…
939	immense (it blocks a thread for a long time) so do not use this function	1335	immense (it blocks a thread for a long time) so do not use this function
940	except to put your application under artificial I/O pressure.	1336	except to put your application under artificial I/O pressure.
941		1337
942	=back	1338	=back
943		1339
		1340
		1341	=head2 IO::AIO::WD - multiple working directories
		1342
		1343	Your process only has one current working directory, which is used by all
		1344	threads. This makes it hard to use relative paths (some other component
		1345	could call C<chdir> at any time, and it is hard to control when the path
		1346	will be used by IO::AIO).
		1347
		1348	One solution for this is to always use absolute paths. This usually works,
		1349	but can be quite slow (the kernel has to walk the whole path on every
		1350	access), and can also be a hassle to implement.
		1351
		1352	Newer POSIX systems have a number of functions (openat, fdopendir,
		1353	futimensat and so on) that make it possible to specify working directories
		1354	per operation.
		1355
		1356	For portability, and because the clowns who "designed", or shall I write,
		1357	perpetrated this new interface were obviously half-drunk, this abstraction
		1358	cannot be perfect, though.
		1359
		1360	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1361	object. This object stores the canonicalised, absolute version of the
		1362	path, and on systems that allow it, also a directory file descriptor.
		1363
		1364	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1365	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1366	object and a pathname instead (or the IO::AIO::WD object alone, which
		1367	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1368	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1369	to that IO::AIO::WD object.
		1370
		1371	For example, to get a wd object for F</etc> and then stat F<passwd>
		1372	inside, you would write:
		1373
		1374	aio_wd "/etc", sub {
		1375	my $etcdir = shift;
		1376
		1377	# although $etcdir can be undef on error, there is generally no reason
		1378	# to check for errors here, as aio_stat will fail with ENOENT
		1379	# when $etcdir is undef.
		1380
		1381	aio_stat [$etcdir, "passwd"], sub {
		1382	# yay
		1383	};
		1384	};
		1385
		1386	That C<aio_wd> is a request and not a normal function shows that creating
		1387	an IO::AIO::WD object is itself a potentially blocking operation, which is
		1388	why it is done asynchronously.
		1389
		1390	To stat the directory obtained with C<aio_wd> above, one could write
		1391	either of the following three request calls:
		1392
		1393	aio_lstat "/etc" , sub { ... # pathname as normal string
		1394	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1395	aio_lstat $wd , sub { ... # shorthand for the previous
		1396
		1397	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1398	object and the pathname string, so you could write the following without
		1399	causing any issues due to C<$path> getting reused:
		1400
		1401	my $path = [$wd, undef];
		1402
		1403	for my $name (qw(abc def ghi)) {
		1404	$path->[1] = $name;
		1405	aio_stat $path, sub {
		1406	# ...
		1407	};
		1408	}
		1409
		1410	There are some caveats: when directories get renamed (or deleted), the
		1411	pathname string doesn't change, so will point to the new directory (or
		1412	nowhere at all), while the directory fd, if available on the system,
		1413	will still point to the original directory. Most functions accepting a
		1414	pathname will use the directory fd on newer systems, and the string on
		1415	older systems. Some functions (such as realpath) will always rely on the
		1416	string form of the pathname.
		1417
		1418	So this fucntionality is mainly useful to get some protection against
		1419	C<chdir>, to easily get an absolute path out of a relative path for future
		1420	reference, and to speed up doing many operations in the same directory
		1421	(e.g. when stat'ing all files in a directory).
		1422
		1423	The following functions implement this working directory abstraction:
		1424
		1425	=over 4
		1426
		1427	=item aio_wd $pathname, $callback->($wd)
		1428
		1429	Asynchonously canonicalise the given pathname and convert it to an
		1430	IO::AIO::WD object representing it. If possible and supported on the
		1431	system, also open a directory fd to speed up pathname resolution relative
		1432	to this working directory.
		1433
		1434	If something goes wrong, then C<undef> is passwd to the callback instead
		1435	of a working directory object and C<$!> is set appropriately. Since
		1436	passing C<undef> as working directory component of a pathname fails the
		1437	request with C<ENOENT>, there is often no need for error checking in the
		1438	C<aio_wd> callback, as future requests using the value will fail in the
		1439	expected way.
		1440
		1441	If this call isn't available because your OS lacks it or it couldn't be
		1442	detected, it will be emulated by calling C<fsync> instead.
		1443
		1444	=item IO::AIO::CWD
		1445
		1446	This is a compiletime constant (object) that represents the process
		1447	current working directory.
		1448
		1449	Specifying this object as working directory object for a pathname is as
		1450	if the pathname would be specified directly, without a directory object,
		1451	e.g., these calls are functionally identical:
		1452
		1453	aio_stat "somefile", sub { ... };
		1454	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1455
		1456	=back
		1457
		1458
944	=head2 IO::AIO::REQ CLASS	1459	=head2 IO::AIO::REQ CLASS
945		1460
946	All non-aggregate C<aio_*> functions return an object of this class when	1461	All non-aggregate C<aio_*> functions return an object of this class when
947	called in non-void context.	1462	called in non-void context.
948		1463
…		…
951	=item cancel $req	1466	=item cancel $req
952		1467
953	Cancels the request, if possible. Has the effect of skipping execution	1468	Cancels the request, if possible. Has the effect of skipping execution
954	when entering the B<execute> state and skipping calling the callback when	1469	when entering the B<execute> state and skipping calling the callback when
955	entering the the B<result> state, but will leave the request otherwise	1470	entering the the B<result> state, but will leave the request otherwise
956	untouched. That means that requests that currently execute will not be	1471	untouched (with the exception of readdir). That means that requests that
957	stopped and resources held by the request will not be freed prematurely.	1472	currently execute will not be stopped and resources held by the request
		1473	will not be freed prematurely.
958		1474
959	=item cb $req $callback->(...)	1475	=item cb $req $callback->(...)
960		1476
961	Replace (or simply set) the callback registered to the request.	1477	Replace (or simply set) the callback registered to the request.
962		1478
…		…
1036	=item $grp->cancel_subs	1552	=item $grp->cancel_subs
1037		1553
1038	Cancel all subrequests and clears any feeder, but not the group request	1554	Cancel all subrequests and clears any feeder, but not the group request
1039	itself. Useful when you queued a lot of events but got a result early.	1555	itself. Useful when you queued a lot of events but got a result early.
1040		1556
		1557	The group request will finish normally (you cannot add requests to the
		1558	group).
		1559
1041	=item $grp->result (...)	1560	=item $grp->result (...)
1042		1561
1043	Set the result value(s) that will be passed to the group callback when all	1562	Set the result value(s) that will be passed to the group callback when all
1044	subrequests have finished and set the groups errno to the current value	1563	subrequests have finished and set the groups errno to the current value
1045	of errno (just like calling C<errno> without an error number). By default,	1564	of errno (just like calling C<errno> without an error number). By default,
…		…
1061		1580
1062	Sets a feeder/generator on this group: every group can have an attached	1581	Sets a feeder/generator on this group: every group can have an attached
1063	generator that generates requests if idle. The idea behind this is that,	1582	generator that generates requests if idle. The idea behind this is that,
1064	although you could just queue as many requests as you want in a group,	1583	although you could just queue as many requests as you want in a group,
1065	this might starve other requests for a potentially long time. For example,	1584	this might starve other requests for a potentially long time. For example,
1066	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1585	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1067	delaying any later requests for a long time.	1586	requests, delaying any later requests for a long time.
1068		1587
1069	To avoid this, and allow incremental generation of requests, you can	1588	To avoid this, and allow incremental generation of requests, you can
1070	instead a group and set a feeder on it that generates those requests. The	1589	instead a group and set a feeder on it that generates those requests. The
1071	feed callback will be called whenever there are few enough (see C<limit>,	1590	feed callback will be called whenever there are few enough (see C<limit>,
1072	below) requests active in the group itself and is expected to queue more	1591	below) requests active in the group itself and is expected to queue more
…		…
1113	=over 4	1632	=over 4
1114		1633
1115	=item $fileno = IO::AIO::poll_fileno	1634	=item $fileno = IO::AIO::poll_fileno
1116		1635
1117	Return the I<request result pipe file descriptor>. This filehandle must be	1636	Return the I<request result pipe file descriptor>. This filehandle must be
1118	polled for reading by some mechanism outside this module (e.g. Event or	1637	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1119	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1638	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1120	to call C<poll_cb> to check the results.	1639	you have to call C<poll_cb> to check the results.
1121		1640
1122	See C<poll_cb> for an example.	1641	See C<poll_cb> for an example.
1123		1642
1124	=item IO::AIO::poll_cb	1643	=item IO::AIO::poll_cb
1125		1644
1126	Process some outstanding events on the result pipe. You have to call this	1645	Process some outstanding events on the result pipe. You have to call
1127	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1646	this regularly. Returns C<0> if all events could be processed (or there
1128	returned earlier for whatever reason. Returns immediately when no events	1647	were no events to process), or C<-1> if it returned earlier for whatever
1129	are outstanding. The amount of events processed depends on the settings of	1648	reason. Returns immediately when no events are outstanding. The amount of
1130	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1649	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1650	C<IO::AIO::max_poll_time>.
1131		1651
1132	If not all requests were processed for whatever reason, the filehandle	1652	If not all requests were processed for whatever reason, the filehandle
1133	will still be ready when C<poll_cb> returns, so normally you don't have to	1653	will still be ready when C<poll_cb> returns, so normally you don't have to
1134	do anything special to have it called later.	1654	do anything special to have it called later.
1135		1655
		1656	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1657	ready, it can be beneficial to call this function from loops which submit
		1658	a lot of requests, to make sure the results get processed when they become
		1659	available and not just when the loop is finished and the event loop takes
		1660	over again. This function returns very fast when there are no outstanding
		1661	requests.
		1662
1136	Example: Install an Event watcher that automatically calls	1663	Example: Install an Event watcher that automatically calls
1137	IO::AIO::poll_cb with high priority:	1664	IO::AIO::poll_cb with high priority (more examples can be found in the
		1665	SYNOPSIS section, at the top of this document):
1138		1666
1139	Event->io (fd => IO::AIO::poll_fileno,	1667	Event->io (fd => IO::AIO::poll_fileno,
1140	poll => 'r', async => 1,	1668	poll => 'r', async => 1,
1141	cb => \&IO::AIO::poll_cb);	1669	cb => \&IO::AIO::poll_cb);
		1670
		1671	=item IO::AIO::poll_wait
		1672
		1673	If there are any outstanding requests and none of them in the result
		1674	phase, wait till the result filehandle becomes ready for reading (simply
		1675	does a C<select> on the filehandle. This is useful if you want to
		1676	synchronously wait for some requests to finish).
		1677
		1678	See C<nreqs> for an example.
		1679
		1680	=item IO::AIO::poll
		1681
		1682	Waits until some requests have been handled.
		1683
		1684	Returns the number of requests processed, but is otherwise strictly
		1685	equivalent to:
		1686
		1687	IO::AIO::poll_wait, IO::AIO::poll_cb
		1688
		1689	=item IO::AIO::flush
		1690
		1691	Wait till all outstanding AIO requests have been handled.
		1692
		1693	Strictly equivalent to:
		1694
		1695	IO::AIO::poll_wait, IO::AIO::poll_cb
		1696	while IO::AIO::nreqs;
1142		1697
1143	=item IO::AIO::max_poll_reqs $nreqs	1698	=item IO::AIO::max_poll_reqs $nreqs
1144		1699
1145	=item IO::AIO::max_poll_time $seconds	1700	=item IO::AIO::max_poll_time $seconds
1146		1701
…		…
1171	# use a low priority so other tasks have priority	1726	# use a low priority so other tasks have priority
1172	Event->io (fd => IO::AIO::poll_fileno,	1727	Event->io (fd => IO::AIO::poll_fileno,
1173	poll => 'r', nice => 1,	1728	poll => 'r', nice => 1,
1174	cb => &IO::AIO::poll_cb);	1729	cb => &IO::AIO::poll_cb);
1175		1730
1176	=item IO::AIO::poll_wait
1177
1178	If there are any outstanding requests and none of them in the result
1179	phase, wait till the result filehandle becomes ready for reading (simply
1180	does a C<select> on the filehandle. This is useful if you want to
1181	synchronously wait for some requests to finish).
1182
1183	See C<nreqs> for an example.
1184
1185	=item IO::AIO::poll
1186
1187	Waits until some requests have been handled.
1188
1189	Returns the number of requests processed, but is otherwise strictly
1190	equivalent to:
1191
1192	IO::AIO::poll_wait, IO::AIO::poll_cb
1193
1194	=item IO::AIO::flush
1195
1196	Wait till all outstanding AIO requests have been handled.
1197
1198	Strictly equivalent to:
1199
1200	IO::AIO::poll_wait, IO::AIO::poll_cb
1201	while IO::AIO::nreqs;
1202
1203	=back	1731	=back
1204		1732
1205	=head3 CONTROLLING THE NUMBER OF THREADS	1733	=head3 CONTROLLING THE NUMBER OF THREADS
1206		1734
1207	=over	1735	=over
…		…
1240		1768
1241	Under normal circumstances you don't need to call this function.	1769	Under normal circumstances you don't need to call this function.
1242		1770
1243	=item IO::AIO::max_idle $nthreads	1771	=item IO::AIO::max_idle $nthreads
1244		1772
1245	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1773	Limit the number of threads (default: 4) that are allowed to idle
1246	threads that did not get a request to process within 10 seconds). That	1774	(i.e., threads that did not get a request to process within the idle
1247	means if a thread becomes idle while C<$nthreads> other threads are also	1775	timeout (default: 10 seconds). That means if a thread becomes idle while
1248	idle, it will free its resources and exit.	1776	C<$nthreads> other threads are also idle, it will free its resources and
		1777	exit.
1249		1778
1250	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1779	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1251	to allow for extremely high load situations, but want to free resources	1780	to allow for extremely high load situations, but want to free resources
1252	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1781	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1253		1782
1254	The default is probably ok in most situations, especially if thread	1783	The default is probably ok in most situations, especially if thread
1255	creation is fast. If thread creation is very slow on your system you might	1784	creation is fast. If thread creation is very slow on your system you might
1256	want to use larger values.	1785	want to use larger values.
1257		1786
		1787	=item IO::AIO::idle_timeout $seconds
		1788
		1789	Sets the minimum idle timeout (default 10) after which worker threads are
		1790	allowed to exit. SEe C<IO::AIO::max_idle>.
		1791
1258	=item IO::AIO::max_outstanding $maxreqs	1792	=item IO::AIO::max_outstanding $maxreqs
		1793
		1794	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1795	you do queue up more than this number of requests, the next call to
		1796	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1797	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1798	longer exceeded.
		1799
		1800	In other words, this setting does not enforce a queue limit, but can be
		1801	used to make poll functions block if the limit is exceeded.
1259		1802
1260	This is a very bad function to use in interactive programs because it	1803	This is a very bad function to use in interactive programs because it
1261	blocks, and a bad way to reduce concurrency because it is inexact: Better	1804	blocks, and a bad way to reduce concurrency because it is inexact: Better
1262	use an C<aio_group> together with a feed callback.	1805	use an C<aio_group> together with a feed callback.
1263		1806
1264	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1807	It's main use is in scripts without an event loop - when you want to stat
1265	do queue up more than this number of requests, the next call to the	1808	a lot of files, you can write somehting like this:
1266	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1267	function will block until the limit is no longer exceeded.
1268		1809
1269	The default value is very large, so there is no practical limit on the	1810	IO::AIO::max_outstanding 32;
1270	number of outstanding requests.
1271		1811
1272	You can still queue as many requests as you want. Therefore,	1812	for my $path (...) {
1273	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1813	aio_stat $path , ...;
1274	as a stop gap to shield against fatal memory overflow (with large values).	1814	IO::AIO::poll_cb;
		1815	}
		1816
		1817	IO::AIO::flush;
		1818
		1819	The call to C<poll_cb> inside the loop will normally return instantly, but
		1820	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1821	some requests have been handled. This keeps the loop from pushing a large
		1822	number of C<aio_stat> requests onto the queue.
		1823
		1824	The default value for C<max_outstanding> is very large, so there is no
		1825	practical limit on the number of outstanding requests.
1275		1826
1276	=back	1827	=back
1277		1828
1278	=head3 STATISTICAL INFORMATION	1829	=head3 STATISTICAL INFORMATION
1279		1830
…		…
1299	Returns the number of requests currently in the pending state (executed,	1850	Returns the number of requests currently in the pending state (executed,
1300	but not yet processed by poll_cb).	1851	but not yet processed by poll_cb).
1301		1852
1302	=back	1853	=back
1303		1854
		1855	=head3 MISCELLANEOUS FUNCTIONS
		1856
		1857	IO::AIO implements some functions that might be useful, but are not
		1858	asynchronous.
		1859
		1860	=over 4
		1861
		1862	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1863
		1864	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1865	but is blocking (this makes most sense if you know the input data is
		1866	likely cached already and the output filehandle is set to non-blocking
		1867	operations).
		1868
		1869	Returns the number of bytes copied, or C<-1> on error.
		1870
		1871	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1872
		1873	Simply calls the C<posix_fadvise> function (see its
		1874	manpage for details). The following advice constants are
		1875	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1876	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1877	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1878
		1879	On systems that do not implement C<posix_fadvise>, this function returns
		1880	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1881
		1882	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1883
		1884	Simply calls the C<posix_madvise> function (see its
		1885	manpage for details). The following advice constants are
		1886	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1887	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1888
		1889	On systems that do not implement C<posix_madvise>, this function returns
		1890	ENOSYS, otherwise the return value of C<posix_madvise>.
		1891
		1892	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1893
		1894	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1895	$scalar (see its manpage for details). The following protect
		1896	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1897	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1898
		1899	On systems that do not implement C<mprotect>, this function returns
		1900	ENOSYS, otherwise the return value of C<mprotect>.
		1901
		1902	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1903
		1904	Memory-maps a file (or anonymous memory range) and attaches it to the
		1905	given C<$scalar>, which will act like a string scalar.
		1906
		1907	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1908	change the string length, and most read-only operations such as copying it
		1909	or searching it with regexes and so on.
		1910
		1911	Anything else is unsafe and will, at best, result in memory leaks.
		1912
		1913	The memory map associated with the C<$scalar> is automatically removed
		1914	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1915	C<IO::AIO::munmap> functions are called.
		1916
		1917	This calls the C<mmap>(2) function internally. See your system's manual
		1918	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1919
		1920	The C<$length> must be larger than zero and smaller than the actual
		1921	filesize.
		1922
		1923	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1924	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1925
		1926	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1927	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1928	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1929	(which is set to C<MAP_ANON> if your system only provides this
		1930	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1931	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1932	C<IO::AIO::MAP_NONBLOCK>
		1933
		1934	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1935
		1936	C<$offset> is the offset from the start of the file - it generally must be
		1937	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1938
		1939	Example:
		1940
		1941	use Digest::MD5;
		1942	use IO::AIO;
		1943
		1944	open my $fh, "<verybigfile"
		1945	or die "$!";
		1946
		1947	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1948	or die "verybigfile: $!";
		1949
		1950	my $fast_md5 = md5 $data;
		1951
		1952	=item IO::AIO::munmap $scalar
		1953
		1954	Removes a previous mmap and undefines the C<$scalar>.
		1955
		1956	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1957
		1958	Calls the C<munlock> function, undoing the effects of a previous
		1959	C<aio_mlock> call (see its description for details).
		1960
		1961	=item IO::AIO::munlockall
		1962
		1963	Calls the C<munlockall> function.
		1964
		1965	On systems that do not implement C<munlockall>, this function returns
		1966	ENOSYS, otherwise the return value of C<munlockall>.
		1967
		1968	=back
		1969
1304	=cut	1970	=cut
1305		1971
1306	min_parallel 8;	1972	min_parallel 8;
1307		1973
1308	END { flush }	1974	END { flush }
1309		1975
1310	1;	1976	1;
1311		1977
		1978	=head1 EVENT LOOP INTEGRATION
		1979
		1980	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1981	automatically into many event loops:
		1982
		1983	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1984	use AnyEvent::AIO;
		1985
		1986	You can also integrate IO::AIO manually into many event loops, here are
		1987	some examples of how to do this:
		1988
		1989	# EV integration
		1990	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1991
		1992	# Event integration
		1993	Event->io (fd => IO::AIO::poll_fileno,
		1994	poll => 'r',
		1995	cb => \&IO::AIO::poll_cb);
		1996
		1997	# Glib/Gtk2 integration
		1998	add_watch Glib::IO IO::AIO::poll_fileno,
		1999	in => sub { IO::AIO::poll_cb; 1 };
		2000
		2001	# Tk integration
		2002	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2003	readable => \&IO::AIO::poll_cb);
		2004
		2005	# Danga::Socket integration
		2006	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2007	\&IO::AIO::poll_cb);
		2008
1312	=head2 FORK BEHAVIOUR	2009	=head2 FORK BEHAVIOUR
1313		2010
1314	This module should do "the right thing" when the process using it forks:	2011	Usage of pthreads in a program changes the semantics of fork
		2012	considerably. Specifically, only async-safe functions can be called after
		2013	fork. Perl doesn't know about this, so in general, you cannot call fork
		2014	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2015	pthreads, so this applies, but many other extensions and (for inexplicable
		2016	reasons) perl itself often is linked against pthreads, so this limitation
		2017	applies to quite a lot of perls.
1315		2018
1316	Before the fork, IO::AIO enters a quiescent state where no requests	2019	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1317	can be added in other threads and no results will be processed. After	2020	only works in the process that loaded it. Forking is fully supported, but
1318	the fork the parent simply leaves the quiescent state and continues	2021	using IO::AIO in the child is not.
1319	request/result processing, while the child frees the request/result queue
1320	(so that the requests started before the fork will only be handled in the
1321	parent). Threads will be started on demand until the limit set in the
1322	parent process has been reached again.
1323		2022
1324	In short: the parent will, after a short pause, continue as if fork had	2023	You might get around by not I<using> IO::AIO before (or after)
1325	not been called, while the child will act as if IO::AIO has not been used	2024	forking. You could also try to call the L<IO::AIO::reinit> function in the
1326	yet.	2025	child:
		2026
		2027	=over 4
		2028
		2029	=item IO::AIO::reinit
		2030
		2031	Abandons all current requests and I/O threads and simply reinitialises all
		2032	data structures. This is not an operation supported by any standards, but
		2033	happens to work on GNU/Linux and some newer BSD systems.
		2034
		2035	The only reasonable use for this function is to call it after forking, if
		2036	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2037	the process will result in undefined behaviour. Calling it at any time
		2038	will also result in any undefined (by POSIX) behaviour.
		2039
		2040	=back
1327		2041
1328	=head2 MEMORY USAGE	2042	=head2 MEMORY USAGE
1329		2043
1330	Per-request usage:	2044	Per-request usage:
1331		2045

Diff Legend

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