ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.180 by root, Wed Mar 31 00:46:18 2010 UTC vs.
Revision 1.264 by root, Mon Jul 18 07:48:01 2016 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my $fh = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
68	=head2 EXAMPLE	68	=head2 EXAMPLE
69		69
70	This is a simple example that uses the EV module and loads	70	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
72		72
73	use Fcntl;
74	use EV;	73	use EV;
75	use IO::AIO;	74	use IO::AIO;
76		75
77	# register the IO::AIO callback with EV	76	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	77	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
79		78
80	# queue the request to open /etc/passwd	79	# queue the request to open /etc/passwd
81	aio_open "/etc/passwd", O_RDONLY, 0, sub {	80	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
82	my $fh = shift	81	my $fh = shift
83	or die "error while opening: $!";	82	or die "error while opening: $!";
84		83
85	# stat'ing filehandles is generally non-blocking	84	# stat'ing filehandles is generally non-blocking
86	my $size = -s $fh;	85	my $size = -s $fh;
…		…
95		94
96	# file contents now in $contents	95	# file contents now in $contents
97	print $contents;	96	print $contents;
98		97
99	# exit event loop and program	98	# exit event loop and program
100	EV::unloop;	99	EV::break;
101	};	100	};
102	};	101	};
103		102
104	# possibly queue up other requests, or open GUI windows,	103	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	104	# check for sockets etc. etc.
106		105
107	# process events as long as there are some:	106	# process events as long as there are some:
108	EV::loop;	107	EV::run;
109		108
110	=head1 REQUEST ANATOMY AND LIFETIME	109	=head1 REQUEST ANATOMY AND LIFETIME
111		110
112	Every C<aio_*> function creates a request. which is a C data structure not	111	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	112	directly visible to Perl.
…		…
168	use common::sense;	167	use common::sense;
169		168
170	use base 'Exporter';	169	use base 'Exporter';
171		170
172	BEGIN {	171	BEGIN {
173	our $VERSION = '3.65';	172	our $VERSION = 4.34;
174		173
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	174	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	175	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	176	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	177	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		178	aio_pathsync aio_readahead aio_fiemap aio_allocate
179	aio_rename aio_link aio_move aio_copy aio_group	179	aio_rename aio_link aio_move aio_copy aio_group
180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
181	aio_chmod aio_utime aio_truncate	181	aio_chmod aio_utime aio_truncate
182	aio_msync aio_mtouch aio_statvfs);	182	aio_msync aio_mtouch aio_mlock aio_mlockall
		183	aio_statvfs
		184	aio_wd);
183		185
184	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	186	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
185	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	187	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
186	min_parallel max_parallel max_idle	188	min_parallel max_parallel max_idle idle_timeout
187	nreqs nready npending nthreads	189	nreqs nready npending nthreads
188	max_poll_time max_poll_reqs	190	max_poll_time max_poll_reqs
189	sendfile fadvise);	191	sendfile fadvise madvise
		192	mmap munmap munlock munlockall);
190		193
191	push @AIO_REQ, qw(aio_busy); # not exported	194	push @AIO_REQ, qw(aio_busy); # not exported
192		195
193	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
194		197
…		…
198		201
199	=head1 FUNCTIONS	202	=head1 FUNCTIONS
200		203
201	=head2 QUICK OVERVIEW	204	=head2 QUICK OVERVIEW
202		205
203	This section simply lists the prototypes of the most important functions	206	This section simply lists the prototypes most of the functions for
204	for quick reference. See the following sections for function-by-function	207	quick reference. See the following sections for function-by-function
205	documentation.	208	documentation.
206		209
		210	aio_wd $pathname, $callback->($wd)
207	aio_open $pathname, $flags, $mode, $callback->($fh)	211	aio_open $pathname, $flags, $mode, $callback->($fh)
208	aio_close $fh, $callback->($status)	212	aio_close $fh, $callback->($status)
		213	aio_seek $fh,$offset,$whence, $callback->($offs)
209	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
210	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
211	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
212	aio_readahead $fh,$offset,$length, $callback->($retval)	217	aio_readahead $fh,$offset,$length, $callback->($retval)
213	aio_stat $fh_or_path, $callback->($status)	218	aio_stat $fh_or_path, $callback->($status)
214	aio_lstat $fh, $callback->($status)	219	aio_lstat $fh, $callback->($status)
215	aio_statvfs $fh_or_path, $callback->($statvfs)	220	aio_statvfs $fh_or_path, $callback->($statvfs)
216	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
217	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		223	aio_chmod $fh_or_path, $mode, $callback->($status)
218	aio_truncate $fh_or_path, $offset, $callback->($status)	224	aio_truncate $fh_or_path, $offset, $callback->($status)
219	aio_chmod $fh_or_path, $mode, $callback->($status)	225	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		226	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
220	aio_unlink $pathname, $callback->($status)	227	aio_unlink $pathname, $callback->($status)
221	aio_mknod $path, $mode, $dev, $callback->($status)	228	aio_mknod $pathname, $mode, $dev, $callback->($status)
222	aio_link $srcpath, $dstpath, $callback->($status)	229	aio_link $srcpath, $dstpath, $callback->($status)
223	aio_symlink $srcpath, $dstpath, $callback->($status)	230	aio_symlink $srcpath, $dstpath, $callback->($status)
224	aio_readlink $path, $callback->($link)	231	aio_readlink $pathname, $callback->($link)
		232	aio_realpath $pathname, $callback->($path)
225	aio_rename $srcpath, $dstpath, $callback->($status)	233	aio_rename $srcpath, $dstpath, $callback->($status)
226	aio_mkdir $pathname, $mode, $callback->($status)	234	aio_mkdir $pathname, $mode, $callback->($status)
227	aio_rmdir $pathname, $callback->($status)	235	aio_rmdir $pathname, $callback->($status)
228	aio_readdir $pathname, $callback->($entries)	236	aio_readdir $pathname, $callback->($entries)
229	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	237	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
230	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	238	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
231	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	239	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		240	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
232	aio_load $path, $data, $callback->($status)	241	aio_load $pathname, $data, $callback->($status)
233	aio_copy $srcpath, $dstpath, $callback->($status)	242	aio_copy $srcpath, $dstpath, $callback->($status)
234	aio_move $srcpath, $dstpath, $callback->($status)	243	aio_move $srcpath, $dstpath, $callback->($status)
235	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
236	aio_rmtree $path, $callback->($status)	244	aio_rmtree $pathname, $callback->($status)
		245	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		246	aio_ioctl $fh, $request, $buf, $callback->($status)
237	aio_sync $callback->($status)	247	aio_sync $callback->($status)
		248	aio_syncfs $fh, $callback->($status)
238	aio_fsync $fh, $callback->($status)	249	aio_fsync $fh, $callback->($status)
239	aio_fdatasync $fh, $callback->($status)	250	aio_fdatasync $fh, $callback->($status)
240	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	251	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
241	aio_pathsync $path, $callback->($status)	252	aio_pathsync $pathname, $callback->($status)
242	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	253	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
243	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	254	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		255	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		256	aio_mlockall $flags, $callback->($status)
244	aio_group $callback->(...)	257	aio_group $callback->(...)
245	aio_nop $callback->()	258	aio_nop $callback->()
246		259
247	$prev_pri = aioreq_pri [$pri]	260	$prev_pri = aioreq_pri [$pri]
248	aioreq_nice $pri_adjust	261	aioreq_nice $pri_adjust
…		…
254	IO::AIO::max_poll_reqs $nreqs	267	IO::AIO::max_poll_reqs $nreqs
255	IO::AIO::max_poll_time $seconds	268	IO::AIO::max_poll_time $seconds
256	IO::AIO::min_parallel $nthreads	269	IO::AIO::min_parallel $nthreads
257	IO::AIO::max_parallel $nthreads	270	IO::AIO::max_parallel $nthreads
258	IO::AIO::max_idle $nthreads	271	IO::AIO::max_idle $nthreads
		272	IO::AIO::idle_timeout $seconds
259	IO::AIO::max_outstanding $maxreqs	273	IO::AIO::max_outstanding $maxreqs
260	IO::AIO::nreqs	274	IO::AIO::nreqs
261	IO::AIO::nready	275	IO::AIO::nready
262	IO::AIO::npending	276	IO::AIO::npending
263		277
264	IO::AIO::sendfile $ofh, $ifh, $offset, $count	278	IO::AIO::sendfile $ofh, $ifh, $offset, $count
265	IO::AIO::fadvise $fh, $offset, $len, $advice	279	IO::AIO::fadvise $fh, $offset, $len, $advice
266	IO::AIO::mlockall $flags	280	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		281	IO::AIO::munmap $scalar
		282	IO::AIO::madvise $scalar, $offset, $length, $advice
		283	IO::AIO::mprotect $scalar, $offset, $length, $protect
		284	IO::AIO::munlock $scalar, $offset = 0, $length = undef
267	IO::AIO::munlockall	285	IO::AIO::munlockall
268		286
269	=head2 AIO REQUEST FUNCTIONS	287	=head2 API NOTES
270		288
271	All the C<aio_*> calls are more or less thin wrappers around the syscall	289	All the C<aio_*> calls are more or less thin wrappers around the syscall
272	with the same name (sans C<aio_>). The arguments are similar or identical,	290	with the same name (sans C<aio_>). The arguments are similar or identical,
273	and they all accept an additional (and optional) C<$callback> argument	291	and they all accept an additional (and optional) C<$callback> argument
274	which must be a code reference. This code reference will get called with	292	which must be a code reference. This code reference will be called after
275	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	293	the syscall has been executed in an asynchronous fashion. The results
276	perl, which usually delivers "false") as its sole argument after the given	294	of the request will be passed as arguments to the callback (and, if an
277	syscall has been executed asynchronously.	295	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		296	most syscalls return C<-1> on error, unlike perl, which usually delivers
		297	"false").
		298
		299	Some requests (such as C<aio_readdir>) pass the actual results and
		300	communicate failures by passing C<undef>.
278		301
279	All functions expecting a filehandle keep a copy of the filehandle	302	All functions expecting a filehandle keep a copy of the filehandle
280	internally until the request has finished.	303	internally until the request has finished.
281		304
282	All functions return request objects of type L<IO::AIO::REQ> that allow	305	All functions return request objects of type L<IO::AIO::REQ> that allow
283	further manipulation of those requests while they are in-flight.	306	further manipulation of those requests while they are in-flight.
284		307
285	The pathnames you pass to these routines I<must> be absolute and	308	The pathnames you pass to these routines I<should> be absolute. The
286	encoded as octets. The reason for the former is that at the time the	309	reason for this is that at the time the request is being executed, the
287	request is being executed, the current working directory could have	310	current working directory could have changed. Alternatively, you can
288	changed. Alternatively, you can make sure that you never change the	311	make sure that you never change the current working directory anywhere
289	current working directory anywhere in the program and then use relative	312	in the program and then use relative paths. You can also take advantage
290	paths.	313	of IO::AIOs working directory abstraction, that lets you specify paths
		314	relative to some previously-opened "working directory object" - see the
		315	description of the C<IO::AIO::WD> class later in this document.
291		316
292	To encode pathnames as octets, either make sure you either: a) always pass	317	To encode pathnames as octets, either make sure you either: a) always pass
293	in filenames you got from outside (command line, readdir etc.) without	318	in filenames you got from outside (command line, readdir etc.) without
294	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	319	tinkering, b) are in your native filesystem encoding, c) use the Encode
295	your pathnames to the locale (or other) encoding in effect in the user	320	module and encode your pathnames to the locale (or other) encoding in
296	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	321	effect in the user environment, d) use Glib::filename_from_unicode on
297	use something else to ensure your scalar has the correct contents.	322	unicode filenames or e) use something else to ensure your scalar has the
		323	correct contents.
298		324
299	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	325	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
300	handles correctly whether it is set or not.	326	handles correctly whether it is set or not.
		327
		328	=head2 AIO REQUEST FUNCTIONS
301		329
302	=over 4	330	=over 4
303		331
304	=item $prev_pri = aioreq_pri [$pri]	332	=item $prev_pri = aioreq_pri [$pri]
305		333
…		…
335		363
336		364
337	=item aio_open $pathname, $flags, $mode, $callback->($fh)	365	=item aio_open $pathname, $flags, $mode, $callback->($fh)
338		366
339	Asynchronously open or create a file and call the callback with a newly	367	Asynchronously open or create a file and call the callback with a newly
340	created filehandle for the file.	368	created filehandle for the file (or C<undef> in case of an error).
341		369
342	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	370	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
343	for an explanation.	371	for an explanation.
344		372
345	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	373	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
352	by the umask in effect then the request is being executed, so better never	380	by the umask in effect then the request is being executed, so better never
353	change the umask.	381	change the umask.
354		382
355	Example:	383	Example:
356		384
357	aio_open "/etc/passwd", O_RDONLY, 0, sub {	385	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
358	if ($_[0]) {	386	if ($_[0]) {
359	print "open successful, fh is $_[0]\n";	387	print "open successful, fh is $_[0]\n";
360	...	388	...
361	} else {	389	} else {
362	die "open failed: $!\n";	390	die "open failed: $!\n";
363	}	391	}
364	};	392	};
365		393
		394	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		395	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		396	following POSIX and non-POSIX constants are available (missing ones on
		397	your system are, as usual, C<0>):
		398
		399	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		400	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		401	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		402
366		403
367	=item aio_close $fh, $callback->($status)	404	=item aio_close $fh, $callback->($status)
368		405
369	Asynchronously close a file and call the callback with the result	406	Asynchronously close a file and call the callback with the result
370	code.	407	code.
…		…
378		415
379	Or in other words: the file descriptor will be closed, but it will not be	416	Or in other words: the file descriptor will be closed, but it will not be
380	free for reuse until the perl filehandle is closed.	417	free for reuse until the perl filehandle is closed.
381		418
382	=cut	419	=cut
		420
		421	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		422
		423	Seeks the filehandle to the new C<$offset>, similarly to perl's
		424	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		425	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		426	C<IO::AIO::SEEK_END>).
		427
		428	The resulting absolute offset will be passed to the callback, or C<-1> in
		429	case of an error.
		430
		431	In theory, the C<$whence> constants could be different than the
		432	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		433	so don't panic.
		434
		435	As a GNU/Linux (and maybe Solaris) extension, also the constants
		436	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		437	could be found. No guarantees about suitability for use in C<aio_seek> or
		438	Perl's C<sysseek> can be made though, although I would naively assume they
		439	"just work".
383		440
384	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	441	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
385		442
386	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	443	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
387		444
…		…
420		477
421	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	478	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
422	reading at byte offset C<$in_offset>, and starts writing at the current	479	reading at byte offset C<$in_offset>, and starts writing at the current
423	file offset of C<$out_fh>. Because of that, it is not safe to issue more	480	file offset of C<$out_fh>. Because of that, it is not safe to issue more
424	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	481	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
425	other.	482	other. The same C<$in_fh> works fine though, as this function does not
		483	move or use the file offset of C<$in_fh>.
426		484
		485	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		486	are written, and there is no way to find out how many more bytes have been
		487	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		488	number of bytes written to C<$out_fh>. Only if the result value equals
		489	C<$length> one can assume that C<$length> bytes have been read.
		490
		491	Unlike with other C<aio_> functions, it makes a lot of sense to use
		492	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		493	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		494	the socket I/O will be non-blocking. Note, however, that you can run
		495	into a trap where C<aio_sendfile> reads some data with readahead, then
		496	fails to write all data, and when the socket is ready the next time, the
		497	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		498	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		499	resource usage.
		500
427	This call tries to make use of a native C<sendfile> syscall to provide	501	This call tries to make use of a native C<sendfile>-like syscall to
428	zero-copy operation. For this to work, C<$out_fh> should refer to a	502	provide zero-copy operation. For this to work, C<$out_fh> should refer to
429	socket, and C<$in_fh> should refer to an mmap'able file.	503	a socket, and C<$in_fh> should refer to an mmap'able file.
430		504
431	If a native sendfile cannot be found or it fails with C<ENOSYS>,	505	If a native sendfile cannot be found or it fails with C<ENOSYS>,
432	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	506	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
433	it will be emulated, so you can call C<aio_sendfile> on any type of	507	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
434	filehandle regardless of the limitations of the operating system.	508	type of filehandle regardless of the limitations of the operating system.
435		509
436	Please note, however, that C<aio_sendfile> can read more bytes from	510	As native sendfile syscalls (as practically any non-POSIX interface hacked
437	C<$in_fh> than are written, and there is no way to find out how many	511	together in a hurry to improve benchmark numbers) tend to be rather buggy
438	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	512	on many systems, this implementation tries to work around some known bugs
439	provides the number of bytes written to C<$out_fh>. Only if the result	513	in Linux and FreeBSD kernels (probably others, too), but that might fail,
440	value equals C<$length> one can assume that C<$length> bytes have been	514	so you really really should check the return value of C<aio_sendfile> -
441	read.	515	fewer bytes than expected might have been transferred.
442		516
443		517
444	=item aio_readahead $fh,$offset,$length, $callback->($retval)	518	=item aio_readahead $fh,$offset,$length, $callback->($retval)
445		519
446	C<aio_readahead> populates the page cache with data from a file so that	520	C<aio_readahead> populates the page cache with data from a file so that
…		…
450	whole pages, so that offset is effectively rounded down to a page boundary	524	whole pages, so that offset is effectively rounded down to a page boundary
451	and bytes are read up to the next page boundary greater than or equal to	525	and bytes are read up to the next page boundary greater than or equal to
452	(off-set+length). C<aio_readahead> does not read beyond the end of the	526	(off-set+length). C<aio_readahead> does not read beyond the end of the
453	file. The current file offset of the file is left unchanged.	527	file. The current file offset of the file is left unchanged.
454		528
455	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	529	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
456	emulated by simply reading the data, which would have a similar effect.	530	be emulated by simply reading the data, which would have a similar effect.
457		531
458		532
459	=item aio_stat $fh_or_path, $callback->($status)	533	=item aio_stat $fh_or_path, $callback->($status)
460		534
461	=item aio_lstat $fh, $callback->($status)	535	=item aio_lstat $fh, $callback->($status)
…		…
468	for an explanation.	542	for an explanation.
469		543
470	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	544	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
471	error when stat'ing a large file, the results will be silently truncated	545	error when stat'ing a large file, the results will be silently truncated
472	unless perl itself is compiled with large file support.	546	unless perl itself is compiled with large file support.
		547
		548	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		549	following constants and functions (if not implemented, the constants will
		550	be C<0> and the functions will either C<croak> or fall back on traditional
		551	behaviour).
		552
		553	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		554	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		555	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
473		556
474	Example: Print the length of F</etc/passwd>:	557	Example: Print the length of F</etc/passwd>:
475		558
476	aio_stat "/etc/passwd", sub {	559	aio_stat "/etc/passwd", sub {
477	$_[0] and die "stat failed: $!";	560	$_[0] and die "stat failed: $!";
…		…
521	namemax => 255,	604	namemax => 255,
522	frsize => 1024,	605	frsize => 1024,
523	fsid => 1810	606	fsid => 1810
524	}	607	}
525		608
		609	Here is a (likely partial - send me updates!) list of fsid values used by
		610	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		611
		612	0x0000adf5 adfs
		613	0x0000adff affs
		614	0x5346414f afs
		615	0x09041934 anon-inode filesystem
		616	0x00000187 autofs
		617	0x42465331 befs
		618	0x1badface bfs
		619	0x42494e4d binfmt_misc
		620	0x9123683e btrfs
		621	0x0027e0eb cgroupfs
		622	0xff534d42 cifs
		623	0x73757245 coda
		624	0x012ff7b7 coh
		625	0x28cd3d45 cramfs
		626	0x453dcd28 cramfs-wend (wrong endianness)
		627	0x64626720 debugfs
		628	0x00001373 devfs
		629	0x00001cd1 devpts
		630	0x0000f15f ecryptfs
		631	0x00414a53 efs
		632	0x0000137d ext
		633	0x0000ef53 ext2/ext3/ext4
		634	0x0000ef51 ext2
		635	0xf2f52010 f2fs
		636	0x00004006 fat
		637	0x65735546 fuseblk
		638	0x65735543 fusectl
		639	0x0bad1dea futexfs
		640	0x01161970 gfs2
		641	0x47504653 gpfs
		642	0x00004244 hfs
		643	0xf995e849 hpfs
		644	0x00c0ffee hostfs
		645	0x958458f6 hugetlbfs
		646	0x2bad1dea inotifyfs
		647	0x00009660 isofs
		648	0x000072b6 jffs2
		649	0x3153464a jfs
		650	0x6b414653 k-afs
		651	0x0bd00bd0 lustre
		652	0x0000137f minix
		653	0x0000138f minix 30 char names
		654	0x00002468 minix v2
		655	0x00002478 minix v2 30 char names
		656	0x00004d5a minix v3
		657	0x19800202 mqueue
		658	0x00004d44 msdos
		659	0x0000564c novell
		660	0x00006969 nfs
		661	0x6e667364 nfsd
		662	0x00003434 nilfs
		663	0x5346544e ntfs
		664	0x00009fa1 openprom
		665	0x7461636F ocfs2
		666	0x00009fa0 proc
		667	0x6165676c pstorefs
		668	0x0000002f qnx4
		669	0x68191122 qnx6
		670	0x858458f6 ramfs
		671	0x52654973 reiserfs
		672	0x00007275 romfs
		673	0x67596969 rpc_pipefs
		674	0x73636673 securityfs
		675	0xf97cff8c selinux
		676	0x0000517b smb
		677	0x534f434b sockfs
		678	0x73717368 squashfs
		679	0x62656572 sysfs
		680	0x012ff7b6 sysv2
		681	0x012ff7b5 sysv4
		682	0x01021994 tmpfs
		683	0x15013346 udf
		684	0x00011954 ufs
		685	0x54190100 ufs byteswapped
		686	0x00009fa2 usbdevfs
		687	0x01021997 v9fs
		688	0xa501fcf5 vxfs
		689	0xabba1974 xenfs
		690	0x012ff7b4 xenix
		691	0x58465342 xfs
		692	0x012fd16d xia
526		693
527	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	694	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
528		695
529	Works like perl's C<utime> function (including the special case of $atime	696	Works like perl's C<utime> function (including the special case of $atime
530	and $mtime being undef). Fractional times are supported if the underlying	697	and $mtime being undef). Fractional times are supported if the underlying
…		…
558	=item aio_truncate $fh_or_path, $offset, $callback->($status)	725	=item aio_truncate $fh_or_path, $offset, $callback->($status)
559		726
560	Works like truncate(2) or ftruncate(2).	727	Works like truncate(2) or ftruncate(2).
561		728
562		729
		730	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		731
		732	Allocates or frees disk space according to the C<$mode> argument. See the
		733	linux C<fallocate> documentation for details.
		734
		735	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		736	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		737	to deallocate a file range.
		738
		739	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		740	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		741	your L<fallocate(2)> manpage).
		742
		743	The file system block size used by C<fallocate> is presumably the
		744	C<f_bsize> returned by C<statvfs>.
		745
		746	If C<fallocate> isn't available or cannot be emulated (currently no
		747	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		748
		749
563	=item aio_chmod $fh_or_path, $mode, $callback->($status)	750	=item aio_chmod $fh_or_path, $mode, $callback->($status)
564		751
565	Works like perl's C<chmod> function.	752	Works like perl's C<chmod> function.
566		753
567		754
…		…
569		756
570	Asynchronously unlink (delete) a file and call the callback with the	757	Asynchronously unlink (delete) a file and call the callback with the
571	result code.	758	result code.
572		759
573		760
574	=item aio_mknod $path, $mode, $dev, $callback->($status)	761	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
575		762
576	[EXPERIMENTAL]	763	[EXPERIMENTAL]
577		764
578	Asynchronously create a device node (or fifo). See mknod(2).	765	Asynchronously create a device node (or fifo). See mknod(2).
579		766
580	The only (POSIX-) portable way of calling this function is:	767	The only (POSIX-) portable way of calling this function is:
581		768
582	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	769	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
583		770
		771	See C<aio_stat> for info about some potentially helpful extra constants
		772	and functions.
584		773
585	=item aio_link $srcpath, $dstpath, $callback->($status)	774	=item aio_link $srcpath, $dstpath, $callback->($status)
586		775
587	Asynchronously create a new link to the existing object at C<$srcpath> at	776	Asynchronously create a new link to the existing object at C<$srcpath> at
588	the path C<$dstpath> and call the callback with the result code.	777	the path C<$dstpath> and call the callback with the result code.
…		…
592		781
593	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	782	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
594	the path C<$dstpath> and call the callback with the result code.	783	the path C<$dstpath> and call the callback with the result code.
595		784
596		785
597	=item aio_readlink $path, $callback->($link)	786	=item aio_readlink $pathname, $callback->($link)
598		787
599	Asynchronously read the symlink specified by C<$path> and pass it to	788	Asynchronously read the symlink specified by C<$path> and pass it to
600	the callback. If an error occurs, nothing or undef gets passed to the	789	the callback. If an error occurs, nothing or undef gets passed to the
601	callback.	790	callback.
602		791
603		792
		793	=item aio_realpath $pathname, $callback->($path)
		794
		795	Asynchronously make the path absolute and resolve any symlinks in
		796	C<$path>. The resulting path only consists of directories (same as
		797	L<Cwd::realpath>).
		798
		799	This request can be used to get the absolute path of the current working
		800	directory by passing it a path of F<.> (a single dot).
		801
		802
604	=item aio_rename $srcpath, $dstpath, $callback->($status)	803	=item aio_rename $srcpath, $dstpath, $callback->($status)
605		804
606	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	805	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
607	rename(2) and call the callback with the result code.	806	rename(2) and call the callback with the result code.
		807
		808	On systems that support the AIO::WD working directory abstraction
		809	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		810	of failing, C<rename> is called on the absolute path of C<$wd>.
608		811
609		812
610	=item aio_mkdir $pathname, $mode, $callback->($status)	813	=item aio_mkdir $pathname, $mode, $callback->($status)
611		814
612	Asynchronously mkdir (create) a directory and call the callback with	815	Asynchronously mkdir (create) a directory and call the callback with
…		…
617	=item aio_rmdir $pathname, $callback->($status)	820	=item aio_rmdir $pathname, $callback->($status)
618		821
619	Asynchronously rmdir (delete) a directory and call the callback with the	822	Asynchronously rmdir (delete) a directory and call the callback with the
620	result code.	823	result code.
621		824
		825	On systems that support the AIO::WD working directory abstraction
		826	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		827	C<rmdir> is called on the absolute path of C<$wd>.
		828
622		829
623	=item aio_readdir $pathname, $callback->($entries)	830	=item aio_readdir $pathname, $callback->($entries)
624		831
625	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	832	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
626	directory (i.e. opendir + readdir + closedir). The entries will not be	833	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
630	array-ref with the filenames.	837	array-ref with the filenames.
631		838
632		839
633	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	840	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
634		841
635	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	842	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
636	behaviour and output format. In case of an error, C<$entries> will be	843	tune behaviour and output format. In case of an error, C<$entries> will be
637	C<undef>.	844	C<undef>.
638		845
639	The flags are a combination of the following constants, ORed together (the	846	The flags are a combination of the following constants, ORed together (the
640	flags will also be passed to the callback, possibly modified):	847	flags will also be passed to the callback, possibly modified):
641		848
642	=over 4	849	=over 4
643		850
644	=item IO::AIO::READDIR_DENTS	851	=item IO::AIO::READDIR_DENTS
645		852
646	When this flag is off, then the callback gets an arrayref with of names	853	When this flag is off, then the callback gets an arrayref consisting of
647	only (as with C<aio_readdir>), otherwise it gets an arrayref with	854	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
648	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	855	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
649	entry in more detail.	856	entry in more detail.
650		857
651	C<$name> is the name of the entry.	858	C<$name> is the name of the entry.
652		859
…		…
665	systems that do not deliver the inode information.	872	systems that do not deliver the inode information.
666		873
667	=item IO::AIO::READDIR_DIRS_FIRST	874	=item IO::AIO::READDIR_DIRS_FIRST
668		875
669	When this flag is set, then the names will be returned in an order where	876	When this flag is set, then the names will be returned in an order where
670	likely directories come first. This is useful when you need to quickly	877	likely directories come first, in optimal stat order. This is useful when
671	find directories, or you want to find all directories while avoiding to	878	you need to quickly find directories, or you want to find all directories
672	stat() each entry.	879	while avoiding to stat() each entry.
673		880
674	If the system returns type information in readdir, then this is used	881	If the system returns type information in readdir, then this is used
675	to find directories directly. Otherwise, likely directories are files	882	to find directories directly. Otherwise, likely directories are names
676	beginning with ".", or otherwise files with no dots, of which files with	883	beginning with ".", or otherwise names with no dots, of which names with
677	short names are tried first.	884	short names are tried first.
678		885
679	=item IO::AIO::READDIR_STAT_ORDER	886	=item IO::AIO::READDIR_STAT_ORDER
680		887
681	When this flag is set, then the names will be returned in an order	888	When this flag is set, then the names will be returned in an order
…		…
688		895
689	=item IO::AIO::READDIR_FOUND_UNKNOWN	896	=item IO::AIO::READDIR_FOUND_UNKNOWN
690		897
691	This flag should not be set when calling C<aio_readdirx>. Instead, it	898	This flag should not be set when calling C<aio_readdirx>. Instead, it
692	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	899	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
693	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	900	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
694	C<$type>'s are known, which can be used to speed up some algorithms.	901	C<$type>'s are known, which can be used to speed up some algorithms.
695		902
696	=back	903	=back
697		904
698		905
699	=item aio_load $path, $data, $callback->($status)	906	=item aio_load $pathname, $data, $callback->($status)
700		907
701	This is a composite request that tries to fully load the given file into	908	This is a composite request that tries to fully load the given file into
702	memory. Status is the same as with aio_read.	909	memory. Status is the same as with aio_read.
703		910
704	=cut	911	=cut
…		…
826	if ($_[0] && $! == EXDEV) {	1033	if ($_[0] && $! == EXDEV) {
827	aioreq_pri $pri;	1034	aioreq_pri $pri;
828	add $grp aio_copy $src, $dst, sub {	1035	add $grp aio_copy $src, $dst, sub {
829	$grp->result ($_[0]);	1036	$grp->result ($_[0]);
830		1037
831	if (!$_[0]) {	1038	unless ($_[0]) {
832	aioreq_pri $pri;	1039	aioreq_pri $pri;
833	add $grp aio_unlink $src;	1040	add $grp aio_unlink $src;
834	}	1041	}
835	};	1042	};
836	} else {	1043	} else {
…		…
839	};	1046	};
840		1047
841	$grp	1048	$grp
842	}	1049	}
843		1050
844	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1051	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
845		1052
846	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1053	Scans a directory (similar to C<aio_readdir>) but additionally tries to
847	efficiently separate the entries of directory C<$path> into two sets of	1054	efficiently separate the entries of directory C<$path> into two sets of
848	names, directories you can recurse into (directories), and ones you cannot	1055	names, directories you can recurse into (directories), and ones you cannot
849	recurse into (everything else, including symlinks to directories).	1056	recurse into (everything else, including symlinks to directories).
…		…
880	Then entries will be sorted into likely directories a non-initial dot	1087	Then entries will be sorted into likely directories a non-initial dot
881	currently) and likely non-directories (see C<aio_readdirx>). Then every	1088	currently) and likely non-directories (see C<aio_readdirx>). Then every
882	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1089	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
883	in order of their inode numbers. If that succeeds, it assumes that the	1090	in order of their inode numbers. If that succeeds, it assumes that the
884	entry is a directory or a symlink to directory (which will be checked	1091	entry is a directory or a symlink to directory (which will be checked
885	seperately). This is often faster than stat'ing the entry itself because	1092	separately). This is often faster than stat'ing the entry itself because
886	filesystems might detect the type of the entry without reading the inode	1093	filesystems might detect the type of the entry without reading the inode
887	data (e.g. ext2fs filetype feature), even on systems that cannot return	1094	data (e.g. ext2fs filetype feature), even on systems that cannot return
888	the filetype information on readdir.	1095	the filetype information on readdir.
889		1096
890	If the known number of directories (link count - 2) has been reached, the	1097	If the known number of directories (link count - 2) has been reached, the
…		…
906		1113
907	my $grp = aio_group $cb;	1114	my $grp = aio_group $cb;
908		1115
909	$maxreq = 4 if $maxreq <= 0;	1116	$maxreq = 4 if $maxreq <= 0;
910		1117
911	# stat once	1118	# get a wd object
912	aioreq_pri $pri;	1119	aioreq_pri $pri;
913	add $grp aio_stat $path, sub {	1120	add $grp aio_wd $path, sub {
		1121	$_[0]
914	return $grp->result () if $_[0];	1122	or return $grp->result ();
915	my $now = time;
916	my $hash1 = join ":", (stat _)[0,1,3,7,9];
917		1123
918	# read the directory entries	1124	my $wd = [shift, "."];
		1125
		1126	# stat once
919	aioreq_pri $pri;	1127	aioreq_pri $pri;
920	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1128	add $grp aio_stat $wd, sub {
921	my $entries = shift
922	or return $grp->result ();	1129	return $grp->result () if $_[0];
		1130	my $now = time;
		1131	my $hash1 = join ":", (stat _)[0,1,3,7,9];
923		1132
924	# stat the dir another time	1133	# read the directory entries
925	aioreq_pri $pri;	1134	aioreq_pri $pri;
		1135	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1136	my $entries = shift
		1137	or return $grp->result ();
		1138
		1139	# stat the dir another time
		1140	aioreq_pri $pri;
926	add $grp aio_stat $path, sub {	1141	add $grp aio_stat $wd, sub {
927	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1142	my $hash2 = join ":", (stat _)[0,1,3,7,9];
928		1143
929	my $ndirs;	1144	my $ndirs;
930		1145
931	# take the slow route if anything looks fishy	1146	# take the slow route if anything looks fishy
932	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1147	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
933	$ndirs = -1;	1148	$ndirs = -1;
934	} else {	1149	} else {
935	# if nlink == 2, we are finished	1150	# if nlink == 2, we are finished
936	# for non-posix-fs's, we rely on nlink < 2	1151	# for non-posix-fs's, we rely on nlink < 2
937	$ndirs = (stat _)[3] - 2	1152	$ndirs = (stat _)[3] - 2
938	or return $grp->result ([], $entries);	1153	or return $grp->result ([], $entries);
939	}	1154	}
940		1155
941	my (@dirs, @nondirs);	1156	my (@dirs, @nondirs);
942		1157
943	my $statgrp = add $grp aio_group sub {	1158	my $statgrp = add $grp aio_group sub {
944	$grp->result (\@dirs, \@nondirs);	1159	$grp->result (\@dirs, \@nondirs);
945	};	1160	};
946		1161
947	limit $statgrp $maxreq;	1162	limit $statgrp $maxreq;
948	feed $statgrp sub {	1163	feed $statgrp sub {
949	return unless @$entries;	1164	return unless @$entries;
950	my $entry = shift @$entries;	1165	my $entry = shift @$entries;
951		1166
952	aioreq_pri $pri;	1167	aioreq_pri $pri;
		1168	$wd->[1] = "$entry/.";
953	add $statgrp aio_stat "$path/$entry/.", sub {	1169	add $statgrp aio_stat $wd, sub {
954	if ($_[0] < 0) {	1170	if ($_[0] < 0) {
955	push @nondirs, $entry;	1171	push @nondirs, $entry;
956	} else {	1172	} else {
957	# need to check for real directory	1173	# need to check for real directory
958	aioreq_pri $pri;	1174	aioreq_pri $pri;
		1175	$wd->[1] = $entry;
959	add $statgrp aio_lstat "$path/$entry", sub {	1176	add $statgrp aio_lstat $wd, sub {
960	if (-d _) {	1177	if (-d _) {
961	push @dirs, $entry;	1178	push @dirs, $entry;
962		1179
963	unless (--$ndirs) {	1180	unless (--$ndirs) {
964	push @nondirs, @$entries;	1181	push @nondirs, @$entries;
965	feed $statgrp;	1182	feed $statgrp;
		1183	}
		1184	} else {
		1185	push @nondirs, $entry;
966	}	1186	}
967	} else {
968	push @nondirs, $entry;
969	}	1187	}
970	}	1188	}
971	}	1189	};
972	};	1190	};
973	};	1191	};
974	};	1192	};
975	};	1193	};
976	};	1194	};
977		1195
978	$grp	1196	$grp
979	}	1197	}
980		1198
981	=item aio_rmtree $path, $callback->($status)	1199	=item aio_rmtree $pathname, $callback->($status)
982		1200
983	Delete a directory tree starting (and including) C<$path>, return the	1201	Delete a directory tree starting (and including) C<$path>, return the
984	status of the final C<rmdir> only. This is a composite request that	1202	status of the final C<rmdir> only. This is a composite request that
985	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1203	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
986	everything else.	1204	everything else.
987		1205
988	=cut	1206	=cut
989		1207
…		…
1011	};	1229	};
1012		1230
1013	$grp	1231	$grp
1014	}	1232	}
1015		1233
		1234	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1235
		1236	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1237
		1238	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1239	they execute asynchronously and pass the return value to the callback.
		1240
		1241	Both calls can be used for a lot of things, some of which make more sense
		1242	to run asynchronously in their own thread, while some others make less
		1243	sense. For example, calls that block waiting for external events, such
		1244	as locking, will also lock down an I/O thread while it is waiting, which
		1245	can deadlock the whole I/O system. At the same time, there might be no
		1246	alternative to using a thread to wait.
		1247
		1248	So in general, you should only use these calls for things that do
		1249	(filesystem) I/O, not for things that wait for other events (network,
		1250	other processes), although if you are careful and know what you are doing,
		1251	you still can.
		1252
		1253	The following constants are available (missing ones are, as usual C<0>):
		1254
		1255	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1256
		1257	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1258	C<FS_IOC_FIEMAP>.
		1259
		1260	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1261	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1262
		1263	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1264	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1265	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1266	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1267	C<FS_FL_USER_MODIFIABLE>.
		1268
		1269	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1270	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1271	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1272	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1273
1016	=item aio_sync $callback->($status)	1274	=item aio_sync $callback->($status)
1017		1275
1018	Asynchronously call sync and call the callback when finished.	1276	Asynchronously call sync and call the callback when finished.
1019		1277
1020	=item aio_fsync $fh, $callback->($status)	1278	=item aio_fsync $fh, $callback->($status)
…		…
1027	Asynchronously call fdatasync on the given filehandle and call the	1285	Asynchronously call fdatasync on the given filehandle and call the
1028	callback with the fdatasync result code.	1286	callback with the fdatasync result code.
1029		1287
1030	If this call isn't available because your OS lacks it or it couldn't be	1288	If this call isn't available because your OS lacks it or it couldn't be
1031	detected, it will be emulated by calling C<fsync> instead.	1289	detected, it will be emulated by calling C<fsync> instead.
		1290
		1291	=item aio_syncfs $fh, $callback->($status)
		1292
		1293	Asynchronously call the syncfs syscall to sync the filesystem associated
		1294	to the given filehandle and call the callback with the syncfs result
		1295	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1296	errno to C<ENOSYS> nevertheless.
1032		1297
1033	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1298	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1034		1299
1035	Sync the data portion of the file specified by C<$offset> and C<$length>	1300	Sync the data portion of the file specified by C<$offset> and C<$length>
1036	to disk (but NOT the metadata), by calling the Linux-specific	1301	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1040	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1305	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1041	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1306	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1042	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1307	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1043	manpage for details.	1308	manpage for details.
1044		1309
1045	=item aio_pathsync $path, $callback->($status)	1310	=item aio_pathsync $pathname, $callback->($status)
1046		1311
1047	This request tries to open, fsync and close the given path. This is a	1312	This request tries to open, fsync and close the given path. This is a
1048	composite request intended to sync directories after directory operations	1313	composite request intended to sync directories after directory operations
1049	(E.g. rename). This might not work on all operating systems or have any	1314	(E.g. rename). This might not work on all operating systems or have any
1050	specific effect, but usually it makes sure that directory changes get	1315	specific effect, but usually it makes sure that directory changes get
…		…
1102		1367
1103	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1368	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1104	scalars.	1369	scalars.
1105		1370
1106	It touches (reads or writes) all memory pages in the specified	1371	It touches (reads or writes) all memory pages in the specified
1107	range inside the scalar. All caveats and parameters are the same	1372	range inside the scalar. All caveats and parameters are the same
1108	as for C<aio_msync>, above, except for flags, which must be either	1373	as for C<aio_msync>, above, except for flags, which must be either
1109	C<0> (which reads all pages and ensures they are instantiated) or	1374	C<0> (which reads all pages and ensures they are instantiated) or
1110	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1375	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1111	writing an octet from it, which dirties the page).	1376	writing an octet from it, which dirties the page).
		1377
		1378	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1379
		1380	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1381	scalars.
		1382
		1383	It reads in all the pages of the underlying storage into memory (if any)
		1384	and locks them, so they are not getting swapped/paged out or removed.
		1385
		1386	If C<$length> is undefined, then the scalar will be locked till the end.
		1387
		1388	On systems that do not implement C<mlock>, this function returns C<-1>
		1389	and sets errno to C<ENOSYS>.
		1390
		1391	Note that the corresponding C<munlock> is synchronous and is
		1392	documented under L<MISCELLANEOUS FUNCTIONS>.
		1393
		1394	Example: open a file, mmap and mlock it - both will be undone when
		1395	C<$data> gets destroyed.
		1396
		1397	open my $fh, "<", $path or die "$path: $!";
		1398	my $data;
		1399	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1400	aio_mlock $data; # mlock in background
		1401
		1402	=item aio_mlockall $flags, $callback->($status)
		1403
		1404	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1405	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1406
		1407	On systems that do not implement C<mlockall>, this function returns C<-1>
		1408	and sets errno to C<ENOSYS>.
		1409
		1410	Note that the corresponding C<munlockall> is synchronous and is
		1411	documented under L<MISCELLANEOUS FUNCTIONS>.
		1412
		1413	Example: asynchronously lock all current and future pages into memory.
		1414
		1415	aio_mlockall IO::AIO::MCL_FUTURE;
		1416
		1417	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1418
		1419	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1420	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1421	the ioctl is not available on your OS, then this request will fail with
		1422	C<ENOSYS>.
		1423
		1424	C<$start> is the starting offset to query extents for, C<$length> is the
		1425	size of the range to query - if it is C<undef>, then the whole file will
		1426	be queried.
		1427
		1428	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1429	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1430	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1431	the data portion.
		1432
		1433	C<$count> is the maximum number of extent records to return. If it is
		1434	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1435	case, if it is C<0>, then the callback receives the number of extents
		1436	instead of the extents themselves (which is unreliable, see below).
		1437
		1438	If an error occurs, the callback receives no arguments. The special
		1439	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1440
		1441	Otherwise, the callback receives an array reference with extent
		1442	structures. Each extent structure is an array reference itself, with the
		1443	following members:
		1444
		1445	[$logical, $physical, $length, $flags]
		1446
		1447	Flags is any combination of the following flag values (typically either C<0>
		1448	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1449
		1450	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1451	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1452	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1453	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1454	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1455	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1456
		1457	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1458	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1459	it to return all extents of a range for files with large number of
		1460	extents. The code works around all these issues if C<$count> is undef.
1112		1461
1113	=item aio_group $callback->(...)	1462	=item aio_group $callback->(...)
1114		1463
1115	This is a very special aio request: Instead of doing something, it is a	1464	This is a very special aio request: Instead of doing something, it is a
1116	container for other aio requests, which is useful if you want to bundle	1465	container for other aio requests, which is useful if you want to bundle
…		…
1153	like sleep and file handle readable/writable, the overhead this creates is	1502	like sleep and file handle readable/writable, the overhead this creates is
1154	immense (it blocks a thread for a long time) so do not use this function	1503	immense (it blocks a thread for a long time) so do not use this function
1155	except to put your application under artificial I/O pressure.	1504	except to put your application under artificial I/O pressure.
1156		1505
1157	=back	1506	=back
		1507
		1508
		1509	=head2 IO::AIO::WD - multiple working directories
		1510
		1511	Your process only has one current working directory, which is used by all
		1512	threads. This makes it hard to use relative paths (some other component
		1513	could call C<chdir> at any time, and it is hard to control when the path
		1514	will be used by IO::AIO).
		1515
		1516	One solution for this is to always use absolute paths. This usually works,
		1517	but can be quite slow (the kernel has to walk the whole path on every
		1518	access), and can also be a hassle to implement.
		1519
		1520	Newer POSIX systems have a number of functions (openat, fdopendir,
		1521	futimensat and so on) that make it possible to specify working directories
		1522	per operation.
		1523
		1524	For portability, and because the clowns who "designed", or shall I write,
		1525	perpetrated this new interface were obviously half-drunk, this abstraction
		1526	cannot be perfect, though.
		1527
		1528	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1529	object. This object stores the canonicalised, absolute version of the
		1530	path, and on systems that allow it, also a directory file descriptor.
		1531
		1532	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1533	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1534	object and a pathname instead (or the IO::AIO::WD object alone, which
		1535	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1536	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1537	to that IO::AIO::WD object.
		1538
		1539	For example, to get a wd object for F</etc> and then stat F<passwd>
		1540	inside, you would write:
		1541
		1542	aio_wd "/etc", sub {
		1543	my $etcdir = shift;
		1544
		1545	# although $etcdir can be undef on error, there is generally no reason
		1546	# to check for errors here, as aio_stat will fail with ENOENT
		1547	# when $etcdir is undef.
		1548
		1549	aio_stat [$etcdir, "passwd"], sub {
		1550	# yay
		1551	};
		1552	};
		1553
		1554	The fact that C<aio_wd> is a request and not a normal function shows that
		1555	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1556	which is why it is done asynchronously.
		1557
		1558	To stat the directory obtained with C<aio_wd> above, one could write
		1559	either of the following three request calls:
		1560
		1561	aio_lstat "/etc" , sub { ... # pathname as normal string
		1562	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1563	aio_lstat $wd , sub { ... # shorthand for the previous
		1564
		1565	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1566	object and the pathname string, so you could write the following without
		1567	causing any issues due to C<$path> getting reused:
		1568
		1569	my $path = [$wd, undef];
		1570
		1571	for my $name (qw(abc def ghi)) {
		1572	$path->[1] = $name;
		1573	aio_stat $path, sub {
		1574	# ...
		1575	};
		1576	}
		1577
		1578	There are some caveats: when directories get renamed (or deleted), the
		1579	pathname string doesn't change, so will point to the new directory (or
		1580	nowhere at all), while the directory fd, if available on the system,
		1581	will still point to the original directory. Most functions accepting a
		1582	pathname will use the directory fd on newer systems, and the string on
		1583	older systems. Some functions (such as realpath) will always rely on the
		1584	string form of the pathname.
		1585
		1586	So this functionality is mainly useful to get some protection against
		1587	C<chdir>, to easily get an absolute path out of a relative path for future
		1588	reference, and to speed up doing many operations in the same directory
		1589	(e.g. when stat'ing all files in a directory).
		1590
		1591	The following functions implement this working directory abstraction:
		1592
		1593	=over 4
		1594
		1595	=item aio_wd $pathname, $callback->($wd)
		1596
		1597	Asynchonously canonicalise the given pathname and convert it to an
		1598	IO::AIO::WD object representing it. If possible and supported on the
		1599	system, also open a directory fd to speed up pathname resolution relative
		1600	to this working directory.
		1601
		1602	If something goes wrong, then C<undef> is passwd to the callback instead
		1603	of a working directory object and C<$!> is set appropriately. Since
		1604	passing C<undef> as working directory component of a pathname fails the
		1605	request with C<ENOENT>, there is often no need for error checking in the
		1606	C<aio_wd> callback, as future requests using the value will fail in the
		1607	expected way.
		1608
		1609	=item IO::AIO::CWD
		1610
		1611	This is a compiletime constant (object) that represents the process
		1612	current working directory.
		1613
		1614	Specifying this object as working directory object for a pathname is as if
		1615	the pathname would be specified directly, without a directory object. For
		1616	example, these calls are functionally identical:
		1617
		1618	aio_stat "somefile", sub { ... };
		1619	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1620
		1621	=back
		1622
		1623	To recover the path associated with an IO::AIO::WD object, you can use
		1624	C<aio_realpath>:
		1625
		1626	aio_realpath $wd, sub {
		1627	warn "path is $_[0]\n";
		1628	};
		1629
		1630	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1631	sometimes, fall back to using an absolue path.
1158		1632
1159	=head2 IO::AIO::REQ CLASS	1633	=head2 IO::AIO::REQ CLASS
1160		1634
1161	All non-aggregate C<aio_*> functions return an object of this class when	1635	All non-aggregate C<aio_*> functions return an object of this class when
1162	called in non-void context.	1636	called in non-void context.
…		…
1280		1754
1281	Sets a feeder/generator on this group: every group can have an attached	1755	Sets a feeder/generator on this group: every group can have an attached
1282	generator that generates requests if idle. The idea behind this is that,	1756	generator that generates requests if idle. The idea behind this is that,
1283	although you could just queue as many requests as you want in a group,	1757	although you could just queue as many requests as you want in a group,
1284	this might starve other requests for a potentially long time. For example,	1758	this might starve other requests for a potentially long time. For example,
1285	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1759	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1286	delaying any later requests for a long time.	1760	requests, delaying any later requests for a long time.
1287		1761
1288	To avoid this, and allow incremental generation of requests, you can	1762	To avoid this, and allow incremental generation of requests, you can
1289	instead a group and set a feeder on it that generates those requests. The	1763	instead a group and set a feeder on it that generates those requests. The
1290	feed callback will be called whenever there are few enough (see C<limit>,	1764	feed callback will be called whenever there are few enough (see C<limit>,
1291	below) requests active in the group itself and is expected to queue more	1765	below) requests active in the group itself and is expected to queue more
…		…
1340		1814
1341	See C<poll_cb> for an example.	1815	See C<poll_cb> for an example.
1342		1816
1343	=item IO::AIO::poll_cb	1817	=item IO::AIO::poll_cb
1344		1818
1345	Process some outstanding events on the result pipe. You have to call this	1819	Process some requests that have reached the result phase (i.e. they have
1346	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1820	been executed but the results are not yet reported). You have to call
1347	returned earlier for whatever reason. Returns immediately when no events	1821	this "regularly" to finish outstanding requests.
1348	are outstanding. The amount of events processed depends on the settings of
1349	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1350		1822
		1823	Returns C<0> if all events could be processed (or there were no
		1824	events to process), or C<-1> if it returned earlier for whatever
		1825	reason. Returns immediately when no events are outstanding. The amount
		1826	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1827	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1828
1351	If not all requests were processed for whatever reason, the filehandle	1829	If not all requests were processed for whatever reason, the poll file
1352	will still be ready when C<poll_cb> returns, so normally you don't have to	1830	descriptor will still be ready when C<poll_cb> returns, so normally you
1353	do anything special to have it called later.	1831	don't have to do anything special to have it called later.
		1832
		1833	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1834	ready, it can be beneficial to call this function from loops which submit
		1835	a lot of requests, to make sure the results get processed when they become
		1836	available and not just when the loop is finished and the event loop takes
		1837	over again. This function returns very fast when there are no outstanding
		1838	requests.
1354		1839
1355	Example: Install an Event watcher that automatically calls	1840	Example: Install an Event watcher that automatically calls
1356	IO::AIO::poll_cb with high priority (more examples can be found in the	1841	IO::AIO::poll_cb with high priority (more examples can be found in the
1357	SYNOPSIS section, at the top of this document):	1842	SYNOPSIS section, at the top of this document):
1358		1843
…		…
1360	poll => 'r', async => 1,	1845	poll => 'r', async => 1,
1361	cb => \&IO::AIO::poll_cb);	1846	cb => \&IO::AIO::poll_cb);
1362		1847
1363	=item IO::AIO::poll_wait	1848	=item IO::AIO::poll_wait
1364		1849
1365	If there are any outstanding requests and none of them in the result	1850	Wait until either at least one request is in the result phase or no
1366	phase, wait till the result filehandle becomes ready for reading (simply	1851	requests are outstanding anymore.
1367	does a C<select> on the filehandle. This is useful if you want to	1852
1368	synchronously wait for some requests to finish).	1853	This is useful if you want to synchronously wait for some requests to
		1854	become ready, without actually handling them.
1369		1855
1370	See C<nreqs> for an example.	1856	See C<nreqs> for an example.
1371		1857
1372	=item IO::AIO::poll	1858	=item IO::AIO::poll
1373		1859
…		…
1460		1946
1461	Under normal circumstances you don't need to call this function.	1947	Under normal circumstances you don't need to call this function.
1462		1948
1463	=item IO::AIO::max_idle $nthreads	1949	=item IO::AIO::max_idle $nthreads
1464		1950
1465	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1951	Limit the number of threads (default: 4) that are allowed to idle
1466	threads that did not get a request to process within 10 seconds). That	1952	(i.e., threads that did not get a request to process within the idle
1467	means if a thread becomes idle while C<$nthreads> other threads are also	1953	timeout (default: 10 seconds). That means if a thread becomes idle while
1468	idle, it will free its resources and exit.	1954	C<$nthreads> other threads are also idle, it will free its resources and
		1955	exit.
1469		1956
1470	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1957	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1471	to allow for extremely high load situations, but want to free resources	1958	to allow for extremely high load situations, but want to free resources
1472	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1959	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1473		1960
1474	The default is probably ok in most situations, especially if thread	1961	The default is probably ok in most situations, especially if thread
1475	creation is fast. If thread creation is very slow on your system you might	1962	creation is fast. If thread creation is very slow on your system you might
1476	want to use larger values.	1963	want to use larger values.
1477		1964
		1965	=item IO::AIO::idle_timeout $seconds
		1966
		1967	Sets the minimum idle timeout (default 10) after which worker threads are
		1968	allowed to exit. SEe C<IO::AIO::max_idle>.
		1969
1478	=item IO::AIO::max_outstanding $maxreqs	1970	=item IO::AIO::max_outstanding $maxreqs
		1971
		1972	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1973	you do queue up more than this number of requests, the next call to
		1974	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1975	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1976	longer exceeded.
		1977
		1978	In other words, this setting does not enforce a queue limit, but can be
		1979	used to make poll functions block if the limit is exceeded.
1479		1980
1480	This is a very bad function to use in interactive programs because it	1981	This is a very bad function to use in interactive programs because it
1481	blocks, and a bad way to reduce concurrency because it is inexact: Better	1982	blocks, and a bad way to reduce concurrency because it is inexact: Better
1482	use an C<aio_group> together with a feed callback.	1983	use an C<aio_group> together with a feed callback.
1483		1984
1484	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1985	Its main use is in scripts without an event loop - when you want to stat
1485	do queue up more than this number of requests, the next call to the	1986	a lot of files, you can write somehting like this:
1486	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1487	function will block until the limit is no longer exceeded.
1488		1987
1489	The default value is very large, so there is no practical limit on the	1988	IO::AIO::max_outstanding 32;
1490	number of outstanding requests.
1491		1989
1492	You can still queue as many requests as you want. Therefore,	1990	for my $path (...) {
1493	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1991	aio_stat $path , ...;
1494	as a stop gap to shield against fatal memory overflow (with large values).	1992	IO::AIO::poll_cb;
		1993	}
		1994
		1995	IO::AIO::flush;
		1996
		1997	The call to C<poll_cb> inside the loop will normally return instantly, but
		1998	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1999	some requests have been handled. This keeps the loop from pushing a large
		2000	number of C<aio_stat> requests onto the queue.
		2001
		2002	The default value for C<max_outstanding> is very large, so there is no
		2003	practical limit on the number of outstanding requests.
1495		2004
1496	=back	2005	=back
1497		2006
1498	=head3 STATISTICAL INFORMATION	2007	=head3 STATISTICAL INFORMATION
1499		2008
…		…
1521		2030
1522	=back	2031	=back
1523		2032
1524	=head3 MISCELLANEOUS FUNCTIONS	2033	=head3 MISCELLANEOUS FUNCTIONS
1525		2034
1526	IO::AIO implements some functions that might be useful, but are not	2035	IO::AIO implements some functions that are useful when you want to use
1527	asynchronous.	2036	some "Advanced I/O" function not available to in Perl, without going the
		2037	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2038	counterpart.
1528		2039
1529	=over 4	2040	=over 4
1530		2041
1531	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2042	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1532		2043
…		…
1537		2048
1538	Returns the number of bytes copied, or C<-1> on error.	2049	Returns the number of bytes copied, or C<-1> on error.
1539		2050
1540	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2051	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1541		2052
1542	Simply calls the C<posix_fadvise> function (see it's	2053	Simply calls the C<posix_fadvise> function (see its
1543	manpage for details). The following advice constants are	2054	manpage for details). The following advice constants are
1544	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2055	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1545	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2056	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1546	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2057	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1547		2058
1548	On systems that do not implement C<posix_fadvise>, this function returns	2059	On systems that do not implement C<posix_fadvise>, this function returns
1549	ENOSYS, otherwise the return value of C<posix_fadvise>.	2060	ENOSYS, otherwise the return value of C<posix_fadvise>.
1550		2061
		2062	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2063
		2064	Simply calls the C<posix_madvise> function (see its
		2065	manpage for details). The following advice constants are
		2066	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2067	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
		2068	C<IO::AIO::MADV_FREE>.
		2069
		2070	On systems that do not implement C<posix_madvise>, this function returns
		2071	ENOSYS, otherwise the return value of C<posix_madvise>.
		2072
		2073	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2074
		2075	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2076	$scalar (see its manpage for details). The following protect
		2077	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2078	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2079
		2080	On systems that do not implement C<mprotect>, this function returns
		2081	ENOSYS, otherwise the return value of C<mprotect>.
		2082
1551	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2083	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1552		2084
1553	Memory-maps a file (or anonymous memory range) and attaches it to the	2085	Memory-maps a file (or anonymous memory range) and attaches it to the
1554	given C<$scalar>, which will act like a string scalar.	2086	given C<$scalar>, which will act like a string scalar. Returns true on
		2087	success, and false otherwise.
1555		2088
1556	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2089	The only operations allowed on the scalar are C<substr>/C<vec> that don't
1557	change the string length, and most read-only operations such as copying it	2090	change the string length, and most read-only operations such as copying it
1558	or searching it with regexes and so on.	2091	or searching it with regexes and so on.
1559		2092
…		…
1570	filesize.	2103	filesize.
1571		2104
1572	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2105	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1573	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2106	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1574		2107
1575	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2108	C<$flags> can be a combination of
1576	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2109	C<IO::AIO::MAP_SHARED> or
1577	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2110	C<IO::AIO::MAP_PRIVATE>,
		2111	or a number of system-specific flags (when not available, the are C<0>):
1578	(which is set to C<MAP_ANON> if your system only provides this	2112	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1579	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2113	C<IO::AIO::MAP_LOCKED>,
1580	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2114	C<IO::AIO::MAP_NORESERVE>,
		2115	C<IO::AIO::MAP_POPULATE>,
1581	C<IO::AIO::MAP_NONBLOCK>	2116	C<IO::AIO::MAP_NONBLOCK>,
		2117	C<IO::AIO::MAP_FIXED>,
		2118	C<IO::AIO::MAP_GROWSDOWN>,
		2119	C<IO::AIO::MAP_32BIT>,
		2120	C<IO::AIO::MAP_HUGETLB> or
		2121	C<IO::AIO::MAP_STACK>.
1582		2122
1583	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2123	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1584		2124
1585	C<$offset> is the offset from the start of the file - it generally must be	2125	C<$offset> is the offset from the start of the file - it generally must be
1586	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2126	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1600		2140
1601	=item IO::AIO::munmap $scalar	2141	=item IO::AIO::munmap $scalar
1602		2142
1603	Removes a previous mmap and undefines the C<$scalar>.	2143	Removes a previous mmap and undefines the C<$scalar>.
1604		2144
1605	=item IO::AIO::mlockall $flags	2145	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1606		2146
1607	Calls the C<mlockall> function with the given C<$flags> (a combination of	2147	Calls the C<munlock> function, undoing the effects of a previous
1608	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL__FUTURE>).	2148	C<aio_mlock> call (see its description for details).
1609
1610	On systems that do not implement C<mlockall>, this function returns
1611	ENOSYS, otherwise the return value of C<mlockall>.
1612		2149
1613	=item IO::AIO::munlockall	2150	=item IO::AIO::munlockall
1614		2151
1615	Calls the C<munlockall> function.	2152	Calls the C<munlockall> function.
1616		2153
1617	On systems that do not implement C<munlockall>, this function returns	2154	On systems that do not implement C<munlockall>, this function returns
1618	ENOSYS, otherwise the return value of C<munlockall>.	2155	ENOSYS, otherwise the return value of C<munlockall>.
		2156
		2157	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2158
		2159	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2160	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2161	should be the file offset.
		2162
		2163	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2164	silently corrupt the data in this case.
		2165
		2166	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2167	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2168	C<IO::AIO::SPLICE_F_GIFT>.
		2169
		2170	See the C<splice(2)> manpage for details.
		2171
		2172	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2173
		2174	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2175	description for C<IO::AIO::splice> above for details.
		2176
		2177	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2178
		2179	Attempts to query or change the pipe buffer size. Obviously works only
		2180	on pipes, and currently works only on GNU/Linux systems, and fails with
		2181	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2182	size on other systems, drop me a note.
		2183
		2184	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2185
		2186	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2187	C<$flags> is missing or C<0>, then this should be the same as a call to
		2188	perl's built-in C<pipe> function and create a new pipe, and works on
		2189	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2190	(..., 4096, O_BINARY)>.
		2191
		2192	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2193	the given flags (Linux 2.6.27, glibc 2.9).
		2194
		2195	On success, the read and write file handles are returned.
		2196
		2197	On error, nothing will be returned. If the pipe2 syscall is missing and
		2198	C<$flags> is non-zero, fails with C<ENOSYS>.
		2199
		2200	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2201	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2202	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1619		2203
1620	=back	2204	=back
1621		2205
1622	=cut	2206	=cut
1623		2207
…		…
1658	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2242	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1659	\&IO::AIO::poll_cb);	2243	\&IO::AIO::poll_cb);
1660		2244
1661	=head2 FORK BEHAVIOUR	2245	=head2 FORK BEHAVIOUR
1662		2246
1663	This module should do "the right thing" when the process using it forks:	2247	Usage of pthreads in a program changes the semantics of fork
		2248	considerably. Specifically, only async-safe functions can be called after
		2249	fork. Perl doesn't know about this, so in general, you cannot call fork
		2250	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2251	pthreads, so this applies, but many other extensions and (for inexplicable
		2252	reasons) perl itself often is linked against pthreads, so this limitation
		2253	applies to quite a lot of perls.
1664		2254
1665	Before the fork, IO::AIO enters a quiescent state where no requests	2255	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1666	can be added in other threads and no results will be processed. After	2256	only works in the process that loaded it. Forking is fully supported, but
1667	the fork the parent simply leaves the quiescent state and continues	2257	using IO::AIO in the child is not.
1668	request/result processing, while the child frees the request/result queue
1669	(so that the requests started before the fork will only be handled in the
1670	parent). Threads will be started on demand until the limit set in the
1671	parent process has been reached again.
1672		2258
1673	In short: the parent will, after a short pause, continue as if fork had	2259	You might get around by not I<using> IO::AIO before (or after)
1674	not been called, while the child will act as if IO::AIO has not been used	2260	forking. You could also try to call the L<IO::AIO::reinit> function in the
1675	yet.	2261	child:
		2262
		2263	=over 4
		2264
		2265	=item IO::AIO::reinit
		2266
		2267	Abandons all current requests and I/O threads and simply reinitialises all
		2268	data structures. This is not an operation supported by any standards, but
		2269	happens to work on GNU/Linux and some newer BSD systems.
		2270
		2271	The only reasonable use for this function is to call it after forking, if
		2272	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2273	the process will result in undefined behaviour. Calling it at any time
		2274	will also result in any undefined (by POSIX) behaviour.
		2275
		2276	=back
1676		2277
1677	=head2 MEMORY USAGE	2278	=head2 MEMORY USAGE
1678		2279
1679	Per-request usage:	2280	Per-request usage:
1680		2281

Diff Legend

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