[ViewVC] Diff of: cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.176 by root, Sun Jan 10 23:05:11 2010 UTC vs.
Revision 1.255 by root, Thu Jun 25 15:20:11 2015 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;
…		…
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 = '3.5';	172	our $VERSION = 4.32;
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_sync
178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	177	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_allocate
		178	aio_pathsync aio_readahead aio_fiemap
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)
237	aio_sync $callback->($status)	245	aio_sync $callback->($status)
		246	aio_syncfs $fh, $callback->($status)
238	aio_fsync $fh, $callback->($status)	247	aio_fsync $fh, $callback->($status)
239	aio_fdatasync $fh, $callback->($status)	248	aio_fdatasync $fh, $callback->($status)
240	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	249	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
241	aio_pathsync $path, $callback->($status)	250	aio_pathsync $pathname, $callback->($status)
242	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	251	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
243	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	252	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		253	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		254	aio_mlockall $flags, $callback->($status)
244	aio_group $callback->(...)	255	aio_group $callback->(...)
245	aio_nop $callback->()	256	aio_nop $callback->()
246		257
247	$prev_pri = aioreq_pri [$pri]	258	$prev_pri = aioreq_pri [$pri]
248	aioreq_nice $pri_adjust	259	aioreq_nice $pri_adjust
…		…
254	IO::AIO::max_poll_reqs $nreqs	265	IO::AIO::max_poll_reqs $nreqs
255	IO::AIO::max_poll_time $seconds	266	IO::AIO::max_poll_time $seconds
256	IO::AIO::min_parallel $nthreads	267	IO::AIO::min_parallel $nthreads
257	IO::AIO::max_parallel $nthreads	268	IO::AIO::max_parallel $nthreads
258	IO::AIO::max_idle $nthreads	269	IO::AIO::max_idle $nthreads
		270	IO::AIO::idle_timeout $seconds
259	IO::AIO::max_outstanding $maxreqs	271	IO::AIO::max_outstanding $maxreqs
260	IO::AIO::nreqs	272	IO::AIO::nreqs
261	IO::AIO::nready	273	IO::AIO::nready
262	IO::AIO::npending	274	IO::AIO::npending
263		275
264	IO::AIO::sendfile $ofh, $ifh, $offset, $count	276	IO::AIO::sendfile $ofh, $ifh, $offset, $count
265	IO::AIO::fadvise $fh, $offset, $len, $advice	277	IO::AIO::fadvise $fh, $offset, $len, $advice
266	IO::AIO::mlockall $flags	278	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		279	IO::AIO::munmap $scalar
		280	IO::AIO::madvise $scalar, $offset, $length, $advice
		281	IO::AIO::mprotect $scalar, $offset, $length, $protect
		282	IO::AIO::munlock $scalar, $offset = 0, $length = undef
267	IO::AIO::munlockall	283	IO::AIO::munlockall
268		284
269	=head2 AIO REQUEST FUNCTIONS	285	=head2 API NOTES
270		286
271	All the C<aio_*> calls are more or less thin wrappers around the syscall	287	All the C<aio_*> calls are more or less thin wrappers around the syscall
272	with the same name (sans C<aio_>). The arguments are similar or identical,	288	with the same name (sans C<aio_>). The arguments are similar or identical,
273	and they all accept an additional (and optional) C<$callback> argument	289	and they all accept an additional (and optional) C<$callback> argument
274	which must be a code reference. This code reference will get called with	290	which must be a code reference. This code reference will be called after
275	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	291	the syscall has been executed in an asynchronous fashion. The results
276	perl, which usually delivers "false") as its sole argument after the given	292	of the request will be passed as arguments to the callback (and, if an
277	syscall has been executed asynchronously.	293	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		294	most syscalls return C<-1> on error, unlike perl, which usually delivers
		295	"false").
		296
		297	Some requests (such as C<aio_readdir>) pass the actual results and
		298	communicate failures by passing C<undef>.
278		299
279	All functions expecting a filehandle keep a copy of the filehandle	300	All functions expecting a filehandle keep a copy of the filehandle
280	internally until the request has finished.	301	internally until the request has finished.
281		302
282	All functions return request objects of type L<IO::AIO::REQ> that allow	303	All functions return request objects of type L<IO::AIO::REQ> that allow
283	further manipulation of those requests while they are in-flight.	304	further manipulation of those requests while they are in-flight.
284		305
285	The pathnames you pass to these routines I<must> be absolute and	306	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	307	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	308	current working directory could have changed. Alternatively, you can
288	changed. Alternatively, you can make sure that you never change the	309	make sure that you never change the current working directory anywhere
289	current working directory anywhere in the program and then use relative	310	in the program and then use relative paths. You can also take advantage
290	paths.	311	of IO::AIOs working directory abstraction, that lets you specify paths
		312	relative to some previously-opened "working directory object" - see the
		313	description of the C<IO::AIO::WD> class later in this document.
291		314
292	To encode pathnames as octets, either make sure you either: a) always pass	315	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	316	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	317	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	318	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)	319	effect in the user environment, d) use Glib::filename_from_unicode on
297	use something else to ensure your scalar has the correct contents.	320	unicode filenames or e) use something else to ensure your scalar has the
		321	correct contents.
298		322
299	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	323	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
300	handles correctly whether it is set or not.	324	handles correctly whether it is set or not.
		325
		326	=head2 AIO REQUEST FUNCTIONS
301		327
302	=over 4	328	=over 4
303		329
304	=item $prev_pri = aioreq_pri [$pri]	330	=item $prev_pri = aioreq_pri [$pri]
305		331
…		…
335		361
336		362
337	=item aio_open $pathname, $flags, $mode, $callback->($fh)	363	=item aio_open $pathname, $flags, $mode, $callback->($fh)
338		364
339	Asynchronously open or create a file and call the callback with a newly	365	Asynchronously open or create a file and call the callback with a newly
340	created filehandle for the file.	366	created filehandle for the file (or C<undef> in case of an error).
341		367
342	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	368	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
343	for an explanation.	369	for an explanation.
344		370
345	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	371	The C<$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	378	by the umask in effect then the request is being executed, so better never
353	change the umask.	379	change the umask.
354		380
355	Example:	381	Example:
356		382
357	aio_open "/etc/passwd", O_RDONLY, 0, sub {	383	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
358	if ($_[0]) {	384	if ($_[0]) {
359	print "open successful, fh is $_[0]\n";	385	print "open successful, fh is $_[0]\n";
360	...	386	...
361	} else {	387	} else {
362	die "open failed: $!\n";	388	die "open failed: $!\n";
363	}	389	}
364	};	390	};
365		391
		392	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		393	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		394	following POSIX and non-POSIX constants are available (missing ones on
		395	your system are, as usual, C<0>):
		396
		397	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		398	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		399	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		400
366		401
367	=item aio_close $fh, $callback->($status)	402	=item aio_close $fh, $callback->($status)
368		403
369	Asynchronously close a file and call the callback with the result	404	Asynchronously close a file and call the callback with the result
370	code.	405	code.
…		…
378		413
379	Or in other words: the file descriptor will be closed, but it will not be	414	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.	415	free for reuse until the perl filehandle is closed.
381		416
382	=cut	417	=cut
		418
		419	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		420
		421	Seeks the filehandle to the new C<$offset>, similarly to perl's
		422	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		423	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		424	C<IO::AIO::SEEK_END>).
		425
		426	The resulting absolute offset will be passed to the callback, or C<-1> in
		427	case of an error.
		428
		429	In theory, the C<$whence> constants could be different than the
		430	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		431	so don't panic.
		432
		433	As a GNU/Linux (and maybe Solaris) extension, also the constants
		434	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		435	could be found. No guarantees about suitability for use in C<aio_seek> or
		436	Perl's C<sysseek> can be made though, although I would naively assume they
		437	"just work".
383		438
384	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	439	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
385		440
386	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	441	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
387		442
…		…
420		475
421	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	476	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
422	reading at byte offset C<$in_offset>, and starts writing at the current	477	reading at byte offset C<$in_offset>, and starts writing at the current
423	file offset of C<$out_fh>. Because of that, it is not safe to issue more	478	file offset of C<$out_fh>. Because of that, it is not safe to issue more
424	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	479	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
425	other.	480	other. The same C<$in_fh> works fine though, as this function does not
		481	move or use the file offset of C<$in_fh>.
426		482
		483	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		484	are written, and there is no way to find out how many more bytes have been
		485	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		486	number of bytes written to C<$out_fh>. Only if the result value equals
		487	C<$length> one can assume that C<$length> bytes have been read.
		488
		489	Unlike with other C<aio_> functions, it makes a lot of sense to use
		490	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		491	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		492	the socket I/O will be non-blocking. Note, however, that you can run
		493	into a trap where C<aio_sendfile> reads some data with readahead, then
		494	fails to write all data, and when the socket is ready the next time, the
		495	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		496	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		497	resource usage.
		498
427	This call tries to make use of a native C<sendfile> syscall to provide	499	This call tries to make use of a native C<sendfile>-like syscall to
428	zero-copy operation. For this to work, C<$out_fh> should refer to a	500	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.	501	a socket, and C<$in_fh> should refer to an mmap'able file.
430		502
431	If a native sendfile cannot be found or it fails with C<ENOSYS>,	503	If a native sendfile cannot be found or it fails with C<ENOSYS>,
432	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	504	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
433	it will be emulated, so you can call C<aio_sendfile> on any type of	505	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
434	filehandle regardless of the limitations of the operating system.	506	type of filehandle regardless of the limitations of the operating system.
435		507
436	Please note, however, that C<aio_sendfile> can read more bytes from	508	As native sendfile syscalls (as practically any non-POSIX interface hacked
437	C<$in_fh> than are written, and there is no way to find out how many	509	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	510	on many systems, this implementation tries to work around some known bugs
439	provides the number of bytes written to C<$out_fh>. Only if the result	511	in Linux and FreeBSD kernels (probably others, too), but that might fail,
440	value equals C<$length> one can assume that C<$length> bytes have been	512	so you really really should check the return value of C<aio_sendfile> -
441	read.	513	fewre bytes than expected might have been transferred.
442		514
443		515
444	=item aio_readahead $fh,$offset,$length, $callback->($retval)	516	=item aio_readahead $fh,$offset,$length, $callback->($retval)
445		517
446	C<aio_readahead> populates the page cache with data from a file so that	518	C<aio_readahead> populates the page cache with data from a file so that
…		…
468	for an explanation.	540	for an explanation.
469		541
470	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	542	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	543	error when stat'ing a large file, the results will be silently truncated
472	unless perl itself is compiled with large file support.	544	unless perl itself is compiled with large file support.
		545
		546	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		547	following constants and functions (if not implemented, the constants will
		548	be C<0> and the functions will either C<croak> or fall back on traditional
		549	behaviour).
		550
		551	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		552	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		553	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
473		554
474	Example: Print the length of F</etc/passwd>:	555	Example: Print the length of F</etc/passwd>:
475		556
476	aio_stat "/etc/passwd", sub {	557	aio_stat "/etc/passwd", sub {
477	$_[0] and die "stat failed: $!";	558	$_[0] and die "stat failed: $!";
…		…
521	namemax => 255,	602	namemax => 255,
522	frsize => 1024,	603	frsize => 1024,
523	fsid => 1810	604	fsid => 1810
524	}	605	}
525		606
		607	Here is a (likely partial - send me updates!) list of fsid values used by
		608	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		609
		610	0x0000adf5 adfs
		611	0x0000adff affs
		612	0x5346414f afs
		613	0x09041934 anon-inode filesystem
		614	0x00000187 autofs
		615	0x42465331 befs
		616	0x1badface bfs
		617	0x42494e4d binfmt_misc
		618	0x9123683e btrfs
		619	0x0027e0eb cgroupfs
		620	0xff534d42 cifs
		621	0x73757245 coda
		622	0x012ff7b7 coh
		623	0x28cd3d45 cramfs
		624	0x453dcd28 cramfs-wend (wrong endianness)
		625	0x64626720 debugfs
		626	0x00001373 devfs
		627	0x00001cd1 devpts
		628	0x0000f15f ecryptfs
		629	0x00414a53 efs
		630	0x0000137d ext
		631	0x0000ef53 ext2/ext3
		632	0x0000ef51 ext2
		633	0x00004006 fat
		634	0x65735546 fuseblk
		635	0x65735543 fusectl
		636	0x0bad1dea futexfs
		637	0x01161970 gfs2
		638	0x47504653 gpfs
		639	0x00004244 hfs
		640	0xf995e849 hpfs
		641	0x958458f6 hugetlbfs
		642	0x2bad1dea inotifyfs
		643	0x00009660 isofs
		644	0x000072b6 jffs2
		645	0x3153464a jfs
		646	0x6b414653 k-afs
		647	0x0bd00bd0 lustre
		648	0x0000137f minix
		649	0x0000138f minix 30 char names
		650	0x00002468 minix v2
		651	0x00002478 minix v2 30 char names
		652	0x00004d5a minix v3
		653	0x19800202 mqueue
		654	0x00004d44 msdos
		655	0x0000564c novell
		656	0x00006969 nfs
		657	0x6e667364 nfsd
		658	0x00003434 nilfs
		659	0x5346544e ntfs
		660	0x00009fa1 openprom
		661	0x7461636F ocfs2
		662	0x00009fa0 proc
		663	0x6165676c pstorefs
		664	0x0000002f qnx4
		665	0x858458f6 ramfs
		666	0x52654973 reiserfs
		667	0x00007275 romfs
		668	0x67596969 rpc_pipefs
		669	0x73636673 securityfs
		670	0xf97cff8c selinux
		671	0x0000517b smb
		672	0x534f434b sockfs
		673	0x73717368 squashfs
		674	0x62656572 sysfs
		675	0x012ff7b6 sysv2
		676	0x012ff7b5 sysv4
		677	0x01021994 tmpfs
		678	0x15013346 udf
		679	0x00011954 ufs
		680	0x54190100 ufs byteswapped
		681	0x00009fa2 usbdevfs
		682	0x01021997 v9fs
		683	0xa501fcf5 vxfs
		684	0xabba1974 xenfs
		685	0x012ff7b4 xenix
		686	0x58465342 xfs
		687	0x012fd16d xia
526		688
527	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	689	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
528		690
529	Works like perl's C<utime> function (including the special case of $atime	691	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	692	and $mtime being undef). Fractional times are supported if the underlying
…		…
558	=item aio_truncate $fh_or_path, $offset, $callback->($status)	720	=item aio_truncate $fh_or_path, $offset, $callback->($status)
559		721
560	Works like truncate(2) or ftruncate(2).	722	Works like truncate(2) or ftruncate(2).
561		723
562		724
		725	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		726
		727	Allocates or frees disk space according to the C<$mode> argument. See the
		728	linux C<fallocate> documentation for details.
		729
		730	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		731	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE \| IO::AIO::FALLOC_FL_KEEP_SIZE>,
		732	to deallocate a file range.
		733
		734	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		735	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		736	your L<fallocate(2)> manpage).
		737
		738	The file system block size used by C<fallocate> is presumably the
		739	C<f_bsize> returned by C<statvfs>.
		740
		741	If C<fallocate> isn't available or cannot be emulated (currently no
		742	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		743
		744
563	=item aio_chmod $fh_or_path, $mode, $callback->($status)	745	=item aio_chmod $fh_or_path, $mode, $callback->($status)
564		746
565	Works like perl's C<chmod> function.	747	Works like perl's C<chmod> function.
566		748
567		749
…		…
569		751
570	Asynchronously unlink (delete) a file and call the callback with the	752	Asynchronously unlink (delete) a file and call the callback with the
571	result code.	753	result code.
572		754
573		755
574	=item aio_mknod $path, $mode, $dev, $callback->($status)	756	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
575		757
576	[EXPERIMENTAL]	758	[EXPERIMENTAL]
577		759
578	Asynchronously create a device node (or fifo). See mknod(2).	760	Asynchronously create a device node (or fifo). See mknod(2).
579		761
580	The only (POSIX-) portable way of calling this function is:	762	The only (POSIX-) portable way of calling this function is:
581		763
582	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	764	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
583		765
		766	See C<aio_stat> for info about some potentially helpful extra constants
		767	and functions.
584		768
585	=item aio_link $srcpath, $dstpath, $callback->($status)	769	=item aio_link $srcpath, $dstpath, $callback->($status)
586		770
587	Asynchronously create a new link to the existing object at C<$srcpath> at	771	Asynchronously create a new link to the existing object at C<$srcpath> at
588	the path C<$dstpath> and call the callback with the result code.	772	the path C<$dstpath> and call the callback with the result code.
…		…
592		776
593	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	777	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
594	the path C<$dstpath> and call the callback with the result code.	778	the path C<$dstpath> and call the callback with the result code.
595		779
596		780
597	=item aio_readlink $path, $callback->($link)	781	=item aio_readlink $pathname, $callback->($link)
598		782
599	Asynchronously read the symlink specified by C<$path> and pass it to	783	Asynchronously read the symlink specified by C<$path> and pass it to
600	the callback. If an error occurs, nothing or undef gets passed to the	784	the callback. If an error occurs, nothing or undef gets passed to the
601	callback.	785	callback.
602		786
603		787
		788	=item aio_realpath $pathname, $callback->($path)
		789
		790	Asynchronously make the path absolute and resolve any symlinks in
		791	C<$path>. The resulting path only consists of directories (same as
		792	L<Cwd::realpath>).
		793
		794	This request can be used to get the absolute path of the current working
		795	directory by passing it a path of F<.> (a single dot).
		796
		797
604	=item aio_rename $srcpath, $dstpath, $callback->($status)	798	=item aio_rename $srcpath, $dstpath, $callback->($status)
605		799
606	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	800	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
607	rename(2) and call the callback with the result code.	801	rename(2) and call the callback with the result code.
		802
		803	On systems that support the AIO::WD working directory abstraction
		804	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		805	of failing, C<rename> is called on the absolute path of C<$wd>.
608		806
609		807
610	=item aio_mkdir $pathname, $mode, $callback->($status)	808	=item aio_mkdir $pathname, $mode, $callback->($status)
611		809
612	Asynchronously mkdir (create) a directory and call the callback with	810	Asynchronously mkdir (create) a directory and call the callback with
…		…
617	=item aio_rmdir $pathname, $callback->($status)	815	=item aio_rmdir $pathname, $callback->($status)
618		816
619	Asynchronously rmdir (delete) a directory and call the callback with the	817	Asynchronously rmdir (delete) a directory and call the callback with the
620	result code.	818	result code.
621		819
		820	On systems that support the AIO::WD working directory abstraction
		821	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		822	C<rmdir> is called on the absolute path of C<$wd>.
		823
622		824
623	=item aio_readdir $pathname, $callback->($entries)	825	=item aio_readdir $pathname, $callback->($entries)
624		826
625	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	827	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	828	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
630	array-ref with the filenames.	832	array-ref with the filenames.
631		833
632		834
633	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	835	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
634		836
635	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	837	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	838	tune behaviour and output format. In case of an error, C<$entries> will be
637	C<undef>.	839	C<undef>.
638		840
639	The flags are a combination of the following constants, ORed together (the	841	The flags are a combination of the following constants, ORed together (the
640	flags will also be passed to the callback, possibly modified):	842	flags will also be passed to the callback, possibly modified):
641		843
642	=over 4	844	=over 4
643		845
644	=item IO::AIO::READDIR_DENTS	846	=item IO::AIO::READDIR_DENTS
645		847
646	When this flag is off, then the callback gets an arrayref with of names	848	When this flag is off, then the callback gets an arrayref consisting of
647	only (as with C<aio_readdir>), otherwise it gets an arrayref with	849	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
648	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	850	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
649	entry in more detail.	851	entry in more detail.
650		852
651	C<$name> is the name of the entry.	853	C<$name> is the name of the entry.
652		854
…		…
665	systems that do not deliver the inode information.	867	systems that do not deliver the inode information.
666		868
667	=item IO::AIO::READDIR_DIRS_FIRST	869	=item IO::AIO::READDIR_DIRS_FIRST
668		870
669	When this flag is set, then the names will be returned in an order where	871	When this flag is set, then the names will be returned in an order where
670	likely directories come first. This is useful when you need to quickly	872	likely directories come first, in optimal stat order. This is useful when
671	find directories, or you want to find all directories while avoiding to	873	you need to quickly find directories, or you want to find all directories
672	stat() each entry.	874	while avoiding to stat() each entry.
673		875
674	If the system returns type information in readdir, then this is used	876	If the system returns type information in readdir, then this is used
675	to find directories directly. Otherwise, likely directories are files	877	to find directories directly. Otherwise, likely directories are names
676	beginning with ".", or otherwise files with no dots, of which files with	878	beginning with ".", or otherwise names with no dots, of which names with
677	short names are tried first.	879	short names are tried first.
678		880
679	=item IO::AIO::READDIR_STAT_ORDER	881	=item IO::AIO::READDIR_STAT_ORDER
680		882
681	When this flag is set, then the names will be returned in an order	883	When this flag is set, then the names will be returned in an order
…		…
688		890
689	=item IO::AIO::READDIR_FOUND_UNKNOWN	891	=item IO::AIO::READDIR_FOUND_UNKNOWN
690		892
691	This flag should not be set when calling C<aio_readdirx>. Instead, it	893	This flag should not be set when calling C<aio_readdirx>. Instead, it
692	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	894	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
693	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	895	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
694	C<$type>'s are known, which can be used to speed up some algorithms.	896	C<$type>'s are known, which can be used to speed up some algorithms.
695		897
696	=back	898	=back
697		899
698		900
699	=item aio_load $path, $data, $callback->($status)	901	=item aio_load $pathname, $data, $callback->($status)
700		902
701	This is a composite request that tries to fully load the given file into	903	This is a composite request that tries to fully load the given file into
702	memory. Status is the same as with aio_read.	904	memory. Status is the same as with aio_read.
703		905
704	=cut	906	=cut
…		…
826	if ($_[0] && $! == EXDEV) {	1028	if ($_[0] && $! == EXDEV) {
827	aioreq_pri $pri;	1029	aioreq_pri $pri;
828	add $grp aio_copy $src, $dst, sub {	1030	add $grp aio_copy $src, $dst, sub {
829	$grp->result ($_[0]);	1031	$grp->result ($_[0]);
830		1032
831	if (!$_[0]) {	1033	unless ($_[0]) {
832	aioreq_pri $pri;	1034	aioreq_pri $pri;
833	add $grp aio_unlink $src;	1035	add $grp aio_unlink $src;
834	}	1036	}
835	};	1037	};
836	} else {	1038	} else {
…		…
839	};	1041	};
840		1042
841	$grp	1043	$grp
842	}	1044	}
843		1045
844	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1046	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
845		1047
846	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1048	Scans a directory (similar to C<aio_readdir>) but additionally tries to
847	efficiently separate the entries of directory C<$path> into two sets of	1049	efficiently separate the entries of directory C<$path> into two sets of
848	names, directories you can recurse into (directories), and ones you cannot	1050	names, directories you can recurse into (directories), and ones you cannot
849	recurse into (everything else, including symlinks to directories).	1051	recurse into (everything else, including symlinks to directories).
…		…
880	Then entries will be sorted into likely directories a non-initial dot	1082	Then entries will be sorted into likely directories a non-initial dot
881	currently) and likely non-directories (see C<aio_readdirx>). Then every	1083	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,	1084	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	1085	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	1086	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	1087	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	1088	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	1089	data (e.g. ext2fs filetype feature), even on systems that cannot return
888	the filetype information on readdir.	1090	the filetype information on readdir.
889		1091
890	If the known number of directories (link count - 2) has been reached, the	1092	If the known number of directories (link count - 2) has been reached, the
…		…
906		1108
907	my $grp = aio_group $cb;	1109	my $grp = aio_group $cb;
908		1110
909	$maxreq = 4 if $maxreq <= 0;	1111	$maxreq = 4 if $maxreq <= 0;
910		1112
911	# stat once	1113	# get a wd object
912	aioreq_pri $pri;	1114	aioreq_pri $pri;
913	add $grp aio_stat $path, sub {	1115	add $grp aio_wd $path, sub {
		1116	$_[0]
914	return $grp->result () if $_[0];	1117	or return $grp->result ();
915	my $now = time;
916	my $hash1 = join ":", (stat _)[0,1,3,7,9];
917		1118
918	# read the directory entries	1119	my $wd = [shift, "."];
		1120
		1121	# stat once
919	aioreq_pri $pri;	1122	aioreq_pri $pri;
920	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1123	add $grp aio_stat $wd, sub {
921	my $entries = shift
922	or return $grp->result ();	1124	return $grp->result () if $_[0];
		1125	my $now = time;
		1126	my $hash1 = join ":", (stat _)[0,1,3,7,9];
923		1127
924	# stat the dir another time	1128	# read the directory entries
925	aioreq_pri $pri;	1129	aioreq_pri $pri;
		1130	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1131	my $entries = shift
		1132	or return $grp->result ();
		1133
		1134	# stat the dir another time
		1135	aioreq_pri $pri;
926	add $grp aio_stat $path, sub {	1136	add $grp aio_stat $wd, sub {
927	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1137	my $hash2 = join ":", (stat _)[0,1,3,7,9];
928		1138
929	my $ndirs;	1139	my $ndirs;
930		1140
931	# take the slow route if anything looks fishy	1141	# take the slow route if anything looks fishy
932	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1142	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
933	$ndirs = -1;	1143	$ndirs = -1;
934	} else {	1144	} else {
935	# if nlink == 2, we are finished	1145	# if nlink == 2, we are finished
936	# for non-posix-fs's, we rely on nlink < 2	1146	# for non-posix-fs's, we rely on nlink < 2
937	$ndirs = (stat _)[3] - 2	1147	$ndirs = (stat _)[3] - 2
938	or return $grp->result ([], $entries);	1148	or return $grp->result ([], $entries);
939	}	1149	}
940		1150
941	my (@dirs, @nondirs);	1151	my (@dirs, @nondirs);
942		1152
943	my $statgrp = add $grp aio_group sub {	1153	my $statgrp = add $grp aio_group sub {
944	$grp->result (\@dirs, \@nondirs);	1154	$grp->result (\@dirs, \@nondirs);
945	};	1155	};
946		1156
947	limit $statgrp $maxreq;	1157	limit $statgrp $maxreq;
948	feed $statgrp sub {	1158	feed $statgrp sub {
949	return unless @$entries;	1159	return unless @$entries;
950	my $entry = shift @$entries;	1160	my $entry = shift @$entries;
951		1161
952	aioreq_pri $pri;	1162	aioreq_pri $pri;
		1163	$wd->[1] = "$entry/.";
953	add $statgrp aio_stat "$path/$entry/.", sub {	1164	add $statgrp aio_stat $wd, sub {
954	if ($_[0] < 0) {	1165	if ($_[0] < 0) {
955	push @nondirs, $entry;	1166	push @nondirs, $entry;
956	} else {	1167	} else {
957	# need to check for real directory	1168	# need to check for real directory
958	aioreq_pri $pri;	1169	aioreq_pri $pri;
		1170	$wd->[1] = $entry;
959	add $statgrp aio_lstat "$path/$entry", sub {	1171	add $statgrp aio_lstat $wd, sub {
960	if (-d _) {	1172	if (-d _) {
961	push @dirs, $entry;	1173	push @dirs, $entry;
962		1174
963	unless (--$ndirs) {	1175	unless (--$ndirs) {
964	push @nondirs, @$entries;	1176	push @nondirs, @$entries;
965	feed $statgrp;	1177	feed $statgrp;
		1178	}
		1179	} else {
		1180	push @nondirs, $entry;
966	}	1181	}
967	} else {
968	push @nondirs, $entry;
969	}	1182	}
970	}	1183	}
971	}	1184	};
972	};	1185	};
973	};	1186	};
974	};	1187	};
975	};	1188	};
976	};	1189	};
977		1190
978	$grp	1191	$grp
979	}	1192	}
980		1193
981	=item aio_rmtree $path, $callback->($status)	1194	=item aio_rmtree $pathname, $callback->($status)
982		1195
983	Delete a directory tree starting (and including) C<$path>, return the	1196	Delete a directory tree starting (and including) C<$path>, return the
984	status of the final C<rmdir> only. This is a composite request that	1197	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	1198	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
986	everything else.	1199	everything else.
987		1200
988	=cut	1201	=cut
989		1202
…		…
1028	callback with the fdatasync result code.	1241	callback with the fdatasync result code.
1029		1242
1030	If this call isn't available because your OS lacks it or it couldn't be	1243	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.	1244	detected, it will be emulated by calling C<fsync> instead.
1032		1245
		1246	=item aio_syncfs $fh, $callback->($status)
		1247
		1248	Asynchronously call the syncfs syscall to sync the filesystem associated
		1249	to the given filehandle and call the callback with the syncfs result
		1250	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1251	errno to C<ENOSYS> nevertheless.
		1252
1033	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1253	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1034		1254
1035	Sync the data portion of the file specified by C<$offset> and C<$length>	1255	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	1256	to disk (but NOT the metadata), by calling the Linux-specific
1037	sync_file_range call. If sync_file_range is not available or it returns	1257	sync_file_range call. If sync_file_range is not available or it returns
…		…
1040	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1260	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1041	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1261	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1042	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1262	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1043	manpage for details.	1263	manpage for details.
1044		1264
1045	=item aio_pathsync $path, $callback->($status)	1265	=item aio_pathsync $pathname, $callback->($status)
1046		1266
1047	This request tries to open, fsync and close the given path. This is a	1267	This request tries to open, fsync and close the given path. This is a
1048	composite request intended to sync directories after directory operations	1268	composite request intended to sync directories after directory operations
1049	(E.g. rename). This might not work on all operating systems or have any	1269	(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	1270	specific effect, but usually it makes sure that directory changes get
…		…
1102		1322
1103	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1323	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1104	scalars.	1324	scalars.
1105		1325
1106	It touches (reads or writes) all memory pages in the specified	1326	It touches (reads or writes) all memory pages in the specified
1107	range inside the scalar. All caveats and parameters are the same	1327	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	1328	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	1329	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	1330	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1111	writing an octet from it, which dirties the page).	1331	writing an octet from it, which dirties the page).
		1332
		1333	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1334
		1335	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1336	scalars.
		1337
		1338	It reads in all the pages of the underlying storage into memory (if any)
		1339	and locks them, so they are not getting swapped/paged out or removed.
		1340
		1341	If C<$length> is undefined, then the scalar will be locked till the end.
		1342
		1343	On systems that do not implement C<mlock>, this function returns C<-1>
		1344	and sets errno to C<ENOSYS>.
		1345
		1346	Note that the corresponding C<munlock> is synchronous and is
		1347	documented under L<MISCELLANEOUS FUNCTIONS>.
		1348
		1349	Example: open a file, mmap and mlock it - both will be undone when
		1350	C<$data> gets destroyed.
		1351
		1352	open my $fh, "<", $path or die "$path: $!";
		1353	my $data;
		1354	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1355	aio_mlock $data; # mlock in background
		1356
		1357	=item aio_mlockall $flags, $callback->($status)
		1358
		1359	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1360	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1361
		1362	On systems that do not implement C<mlockall>, this function returns C<-1>
		1363	and sets errno to C<ENOSYS>.
		1364
		1365	Note that the corresponding C<munlockall> is synchronous and is
		1366	documented under L<MISCELLANEOUS FUNCTIONS>.
		1367
		1368	Example: asynchronously lock all current and future pages into memory.
		1369
		1370	aio_mlockall IO::AIO::MCL_FUTURE;
		1371
		1372	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1373
		1374	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1375	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1376	the ioctl is not available on your OS, then this request will fail with
		1377	C<ENOSYS>.
		1378
		1379	C<$start> is the starting offset to query extents for, C<$length> is the
		1380	size of the range to query - if it is C<undef>, then the whole file will
		1381	be queried.
		1382
		1383	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1384	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1385	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1386	the data portion.
		1387
		1388	C<$count> is the maximum number of extent records to return. If it is
		1389	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1390	case, if it is C<0>, then the callback receives the number of extents
		1391	instead of the extents themselves (which is unreliable, see below).
		1392
		1393	If an error occurs, the callback receives no arguments. The special
		1394	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1395
		1396	Otherwise, the callback receives an array reference with extent
		1397	structures. Each extent structure is an array reference itself, with the
		1398	following members:
		1399
		1400	[$logical, $physical, $length, $flags]
		1401
		1402	Flags is any combination of the following flag values (typically either C<0>
		1403	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1404
		1405	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1406	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1407	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1408	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1409	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1410	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1411
		1412	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1413	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1414	it to return all extents of a range for files with large number of
		1415	extents. The code works around all these issues if C<$count> is undef.
1112		1416
1113	=item aio_group $callback->(...)	1417	=item aio_group $callback->(...)
1114		1418
1115	This is a very special aio request: Instead of doing something, it is a	1419	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	1420	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	1457	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	1458	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.	1459	except to put your application under artificial I/O pressure.
1156		1460
1157	=back	1461	=back
		1462
		1463
		1464	=head2 IO::AIO::WD - multiple working directories
		1465
		1466	Your process only has one current working directory, which is used by all
		1467	threads. This makes it hard to use relative paths (some other component
		1468	could call C<chdir> at any time, and it is hard to control when the path
		1469	will be used by IO::AIO).
		1470
		1471	One solution for this is to always use absolute paths. This usually works,
		1472	but can be quite slow (the kernel has to walk the whole path on every
		1473	access), and can also be a hassle to implement.
		1474
		1475	Newer POSIX systems have a number of functions (openat, fdopendir,
		1476	futimensat and so on) that make it possible to specify working directories
		1477	per operation.
		1478
		1479	For portability, and because the clowns who "designed", or shall I write,
		1480	perpetrated this new interface were obviously half-drunk, this abstraction
		1481	cannot be perfect, though.
		1482
		1483	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1484	object. This object stores the canonicalised, absolute version of the
		1485	path, and on systems that allow it, also a directory file descriptor.
		1486
		1487	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1488	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1489	object and a pathname instead (or the IO::AIO::WD object alone, which
		1490	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1491	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1492	to that IO::AIO::WD object.
		1493
		1494	For example, to get a wd object for F</etc> and then stat F<passwd>
		1495	inside, you would write:
		1496
		1497	aio_wd "/etc", sub {
		1498	my $etcdir = shift;
		1499
		1500	# although $etcdir can be undef on error, there is generally no reason
		1501	# to check for errors here, as aio_stat will fail with ENOENT
		1502	# when $etcdir is undef.
		1503
		1504	aio_stat [$etcdir, "passwd"], sub {
		1505	# yay
		1506	};
		1507	};
		1508
		1509	The fact that C<aio_wd> is a request and not a normal function shows that
		1510	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1511	which is why it is done asynchronously.
		1512
		1513	To stat the directory obtained with C<aio_wd> above, one could write
		1514	either of the following three request calls:
		1515
		1516	aio_lstat "/etc" , sub { ... # pathname as normal string
		1517	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1518	aio_lstat $wd , sub { ... # shorthand for the previous
		1519
		1520	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1521	object and the pathname string, so you could write the following without
		1522	causing any issues due to C<$path> getting reused:
		1523
		1524	my $path = [$wd, undef];
		1525
		1526	for my $name (qw(abc def ghi)) {
		1527	$path->[1] = $name;
		1528	aio_stat $path, sub {
		1529	# ...
		1530	};
		1531	}
		1532
		1533	There are some caveats: when directories get renamed (or deleted), the
		1534	pathname string doesn't change, so will point to the new directory (or
		1535	nowhere at all), while the directory fd, if available on the system,
		1536	will still point to the original directory. Most functions accepting a
		1537	pathname will use the directory fd on newer systems, and the string on
		1538	older systems. Some functions (such as realpath) will always rely on the
		1539	string form of the pathname.
		1540
		1541	So this functionality is mainly useful to get some protection against
		1542	C<chdir>, to easily get an absolute path out of a relative path for future
		1543	reference, and to speed up doing many operations in the same directory
		1544	(e.g. when stat'ing all files in a directory).
		1545
		1546	The following functions implement this working directory abstraction:
		1547
		1548	=over 4
		1549
		1550	=item aio_wd $pathname, $callback->($wd)
		1551
		1552	Asynchonously canonicalise the given pathname and convert it to an
		1553	IO::AIO::WD object representing it. If possible and supported on the
		1554	system, also open a directory fd to speed up pathname resolution relative
		1555	to this working directory.
		1556
		1557	If something goes wrong, then C<undef> is passwd to the callback instead
		1558	of a working directory object and C<$!> is set appropriately. Since
		1559	passing C<undef> as working directory component of a pathname fails the
		1560	request with C<ENOENT>, there is often no need for error checking in the
		1561	C<aio_wd> callback, as future requests using the value will fail in the
		1562	expected way.
		1563
		1564	=item IO::AIO::CWD
		1565
		1566	This is a compiletime constant (object) that represents the process
		1567	current working directory.
		1568
		1569	Specifying this object as working directory object for a pathname is as if
		1570	the pathname would be specified directly, without a directory object. For
		1571	example, these calls are functionally identical:
		1572
		1573	aio_stat "somefile", sub { ... };
		1574	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1575
		1576	=back
		1577
		1578	To recover the path associated with an IO::AIO::WD object, you can use
		1579	C<aio_realpath>:
		1580
		1581	aio_realpath $wd, sub {
		1582	warn "path is $_[0]\n";
		1583	};
		1584
		1585	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1586	sometimes, fall back to using an absolue path.
1158		1587
1159	=head2 IO::AIO::REQ CLASS	1588	=head2 IO::AIO::REQ CLASS
1160		1589
1161	All non-aggregate C<aio_*> functions return an object of this class when	1590	All non-aggregate C<aio_*> functions return an object of this class when
1162	called in non-void context.	1591	called in non-void context.
…		…
1280		1709
1281	Sets a feeder/generator on this group: every group can have an attached	1710	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,	1711	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,	1712	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,	1713	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,	1714	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1286	delaying any later requests for a long time.	1715	requests, delaying any later requests for a long time.
1287		1716
1288	To avoid this, and allow incremental generation of requests, you can	1717	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	1718	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>,	1719	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	1720	below) requests active in the group itself and is expected to queue more
…		…
1340		1769
1341	See C<poll_cb> for an example.	1770	See C<poll_cb> for an example.
1342		1771
1343	=item IO::AIO::poll_cb	1772	=item IO::AIO::poll_cb
1344		1773
1345	Process some outstanding events on the result pipe. You have to call this	1774	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	1775	been executed but the results are not yet reported). You have to call
1347	returned earlier for whatever reason. Returns immediately when no events	1776	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		1777
		1778	Returns C<0> if all events could be processed (or there were no
		1779	events to process), or C<-1> if it returned earlier for whatever
		1780	reason. Returns immediately when no events are outstanding. The amount
		1781	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1782	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1783
1351	If not all requests were processed for whatever reason, the filehandle	1784	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	1785	descriptor will still be ready when C<poll_cb> returns, so normally you
1353	do anything special to have it called later.	1786	don't have to do anything special to have it called later.
		1787
		1788	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1789	ready, it can be beneficial to call this function from loops which submit
		1790	a lot of requests, to make sure the results get processed when they become
		1791	available and not just when the loop is finished and the event loop takes
		1792	over again. This function returns very fast when there are no outstanding
		1793	requests.
1354		1794
1355	Example: Install an Event watcher that automatically calls	1795	Example: Install an Event watcher that automatically calls
1356	IO::AIO::poll_cb with high priority (more examples can be found in the	1796	IO::AIO::poll_cb with high priority (more examples can be found in the
1357	SYNOPSIS section, at the top of this document):	1797	SYNOPSIS section, at the top of this document):
1358		1798
…		…
1360	poll => 'r', async => 1,	1800	poll => 'r', async => 1,
1361	cb => \&IO::AIO::poll_cb);	1801	cb => \&IO::AIO::poll_cb);
1362		1802
1363	=item IO::AIO::poll_wait	1803	=item IO::AIO::poll_wait
1364		1804
1365	If there are any outstanding requests and none of them in the result	1805	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	1806	requests are outstanding anymore.
1367	does a C<select> on the filehandle. This is useful if you want to	1807
1368	synchronously wait for some requests to finish).	1808	This is useful if you want to synchronously wait for some requests to
		1809	become ready, without actually handling them.
1369		1810
1370	See C<nreqs> for an example.	1811	See C<nreqs> for an example.
1371		1812
1372	=item IO::AIO::poll	1813	=item IO::AIO::poll
1373		1814
…		…
1460		1901
1461	Under normal circumstances you don't need to call this function.	1902	Under normal circumstances you don't need to call this function.
1462		1903
1463	=item IO::AIO::max_idle $nthreads	1904	=item IO::AIO::max_idle $nthreads
1464		1905
1465	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1906	Limit the number of threads (default: 4) that are allowed to idle
1466	threads that did not get a request to process within 10 seconds). That	1907	(i.e., threads that did not get a request to process within the idle
1467	means if a thread becomes idle while C<$nthreads> other threads are also	1908	timeout (default: 10 seconds). That means if a thread becomes idle while
1468	idle, it will free its resources and exit.	1909	C<$nthreads> other threads are also idle, it will free its resources and
		1910	exit.
1469		1911
1470	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1912	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	1913	to allow for extremely high load situations, but want to free resources
1472	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1914	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1473		1915
1474	The default is probably ok in most situations, especially if thread	1916	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	1917	creation is fast. If thread creation is very slow on your system you might
1476	want to use larger values.	1918	want to use larger values.
1477		1919
		1920	=item IO::AIO::idle_timeout $seconds
		1921
		1922	Sets the minimum idle timeout (default 10) after which worker threads are
		1923	allowed to exit. SEe C<IO::AIO::max_idle>.
		1924
1478	=item IO::AIO::max_outstanding $maxreqs	1925	=item IO::AIO::max_outstanding $maxreqs
		1926
		1927	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1928	you do queue up more than this number of requests, the next call to
		1929	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1930	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1931	longer exceeded.
		1932
		1933	In other words, this setting does not enforce a queue limit, but can be
		1934	used to make poll functions block if the limit is exceeded.
1479		1935
1480	This is a very bad function to use in interactive programs because it	1936	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	1937	blocks, and a bad way to reduce concurrency because it is inexact: Better
1482	use an C<aio_group> together with a feed callback.	1938	use an C<aio_group> together with a feed callback.
1483		1939
1484	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1940	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	1941	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		1942
1489	The default value is very large, so there is no practical limit on the	1943	IO::AIO::max_outstanding 32;
1490	number of outstanding requests.
1491		1944
1492	You can still queue as many requests as you want. Therefore,	1945	for my $path (...) {
1493	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1946	aio_stat $path , ...;
1494	as a stop gap to shield against fatal memory overflow (with large values).	1947	IO::AIO::poll_cb;
		1948	}
		1949
		1950	IO::AIO::flush;
		1951
		1952	The call to C<poll_cb> inside the loop will normally return instantly, but
		1953	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1954	some requests have been handled. This keeps the loop from pushing a large
		1955	number of C<aio_stat> requests onto the queue.
		1956
		1957	The default value for C<max_outstanding> is very large, so there is no
		1958	practical limit on the number of outstanding requests.
1495		1959
1496	=back	1960	=back
1497		1961
1498	=head3 STATISTICAL INFORMATION	1962	=head3 STATISTICAL INFORMATION
1499		1963
…		…
1521		1985
1522	=back	1986	=back
1523		1987
1524	=head3 MISCELLANEOUS FUNCTIONS	1988	=head3 MISCELLANEOUS FUNCTIONS
1525		1989
1526	IO::AIO implements some functions that might be useful, but are not	1990	IO::AIO implements some functions that are useful when you want to use
1527	asynchronous.	1991	some "Advanced I/O" function not available to in Perl, without going the
		1992	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		1993	counterpart.
1528		1994
1529	=over 4	1995	=over 4
1530		1996
1531	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	1997	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1532		1998
…		…
1537		2003
1538	Returns the number of bytes copied, or C<-1> on error.	2004	Returns the number of bytes copied, or C<-1> on error.
1539		2005
1540	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2006	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1541		2007
1542	Simply calls the C<posix_fadvise> function (see it's	2008	Simply calls the C<posix_fadvise> function (see its
1543	manpage for details). The following advice constants are	2009	manpage for details). The following advice constants are
1544	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2010	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1545	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2011	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1546	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2012	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1547		2013
1548	On systems that do not implement C<posix_fadvise>, this function returns	2014	On systems that do not implement C<posix_fadvise>, this function returns
1549	ENOSYS, otherwise the return value of C<posix_fadvise>.	2015	ENOSYS, otherwise the return value of C<posix_fadvise>.
1550		2016
		2017	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2018
		2019	Simply calls the C<posix_madvise> function (see its
		2020	manpage for details). The following advice constants are
		2021	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2022	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		2023
		2024	On systems that do not implement C<posix_madvise>, this function returns
		2025	ENOSYS, otherwise the return value of C<posix_madvise>.
		2026
		2027	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2028
		2029	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2030	$scalar (see its manpage for details). The following protect
		2031	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2032	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2033
		2034	On systems that do not implement C<mprotect>, this function returns
		2035	ENOSYS, otherwise the return value of C<mprotect>.
		2036
1551	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2037	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1552		2038
1553	Memory-maps a file (or anonymous memory range) and attaches it to the	2039	Memory-maps a file (or anonymous memory range) and attaches it to the
1554	given C<$scalar>, which will act like a string scalar.	2040	given C<$scalar>, which will act like a string scalar. Returns true on
		2041	success, and false otherwise.
1555		2042
1556	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2043	The only operations allowed on the scalar are C<substr>/C<vec> that don't
1557	change the string length, and most read-only operations such as copying it	2044	change the string length, and most read-only operations such as copying it
1558	or searching it with regexes and so on.	2045	or searching it with regexes and so on.
1559		2046
…		…
1580	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2067	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1581	C<IO::AIO::MAP_NONBLOCK>	2068	C<IO::AIO::MAP_NONBLOCK>
1582		2069
1583	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2070	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1584		2071
		2072	C<$offset> is the offset from the start of the file - it generally must be
		2073	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2074
		2075	Example:
		2076
		2077	use Digest::MD5;
		2078	use IO::AIO;
		2079
		2080	open my $fh, "<verybigfile"
		2081	or die "$!";
		2082
		2083	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2084	or die "verybigfile: $!";
		2085
		2086	my $fast_md5 = md5 $data;
		2087
1585	=item IO::AIO::munmap $scalar	2088	=item IO::AIO::munmap $scalar
1586		2089
1587	Removes a previous mmap and undefines the C<$scalar>.	2090	Removes a previous mmap and undefines the C<$scalar>.
1588		2091
1589	=item IO::AIO::mlockall $flags	2092	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1590		2093
1591	Calls the C<mlockall> function with the given C<$flags> (a combination of	2094	Calls the C<munlock> function, undoing the effects of a previous
1592	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL__FUTURE>).	2095	C<aio_mlock> call (see its description for details).
1593
1594	On systems that do not implement C<mlockall>, this function returns
1595	ENOSYS, otherwise the return value of C<mlockall>.
1596		2096
1597	=item IO::AIO::munlockall	2097	=item IO::AIO::munlockall
1598		2098
1599	Calls the C<munlockall> function.	2099	Calls the C<munlockall> function.
1600		2100
1601	On systems that do not implement C<munlockall>, this function returns	2101	On systems that do not implement C<munlockall>, this function returns
1602	ENOSYS, otherwise the return value of C<munlockall>.	2102	ENOSYS, otherwise the return value of C<munlockall>.
		2103
		2104	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2105
		2106	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2107	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2108	should be the file offset.
		2109
		2110	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2111	silently corrupt the data in this case.
		2112
		2113	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2114	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2115	C<IO::AIO::SPLICE_F_GIFT>.
		2116
		2117	See the C<splice(2)> manpage for details.
		2118
		2119	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2120
		2121	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2122	description for C<IO::AIO::splice> above for details.
		2123
		2124	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2125
		2126	Attempts to query or change the pipe buffer size. Obviously works only
		2127	on pipes, and currently works only on GNU/Linux systems, and fails with
		2128	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2129	size on other systems, drop me a note.
		2130
		2131	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2132
		2133	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2134	C<$flags> is missing or C<0>, then this should be the same as a call to
		2135	perl's built-in C<pipe> function and create a new pipe, and works on
		2136	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2137	(..., 4096, O_BINARY)>.
		2138
		2139	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2140	the given flags (Linux 2.6.27, glibc 2.9).
		2141
		2142	On success, the read and write file handles are returned.
		2143
		2144	On error, nothing will be returned. If the pipe2 syscall is missing and
		2145	C<$flags> is non-zero, fails with C<ENOSYS>.
		2146
		2147	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2148	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2149	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1603		2150
1604	=back	2151	=back
1605		2152
1606	=cut	2153	=cut
1607		2154
…		…
1642	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2189	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1643	\&IO::AIO::poll_cb);	2190	\&IO::AIO::poll_cb);
1644		2191
1645	=head2 FORK BEHAVIOUR	2192	=head2 FORK BEHAVIOUR
1646		2193
1647	This module should do "the right thing" when the process using it forks:	2194	Usage of pthreads in a program changes the semantics of fork
		2195	considerably. Specifically, only async-safe functions can be called after
		2196	fork. Perl doesn't know about this, so in general, you cannot call fork
		2197	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2198	pthreads, so this applies, but many other extensions and (for inexplicable
		2199	reasons) perl itself often is linked against pthreads, so this limitation
		2200	applies to quite a lot of perls.
1648		2201
1649	Before the fork, IO::AIO enters a quiescent state where no requests	2202	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1650	can be added in other threads and no results will be processed. After	2203	only works in the process that loaded it. Forking is fully supported, but
1651	the fork the parent simply leaves the quiescent state and continues	2204	using IO::AIO in the child is not.
1652	request/result processing, while the child frees the request/result queue
1653	(so that the requests started before the fork will only be handled in the
1654	parent). Threads will be started on demand until the limit set in the
1655	parent process has been reached again.
1656		2205
1657	In short: the parent will, after a short pause, continue as if fork had	2206	You might get around by not I<using> IO::AIO before (or after)
1658	not been called, while the child will act as if IO::AIO has not been used	2207	forking. You could also try to call the L<IO::AIO::reinit> function in the
1659	yet.	2208	child:
		2209
		2210	=over 4
		2211
		2212	=item IO::AIO::reinit
		2213
		2214	Abandons all current requests and I/O threads and simply reinitialises all
		2215	data structures. This is not an operation supported by any standards, but
		2216	happens to work on GNU/Linux and some newer BSD systems.
		2217
		2218	The only reasonable use for this function is to call it after forking, if
		2219	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2220	the process will result in undefined behaviour. Calling it at any time
		2221	will also result in any undefined (by POSIX) behaviour.
		2222
		2223	=back
1660		2224
1661	=head2 MEMORY USAGE	2225	=head2 MEMORY USAGE
1662		2226
1663	Per-request usage:	2227	Per-request usage:
1664		2228

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.176 by root, Sun Jan 10 23:05:11 2010 UTC vs. Revision 1.255 by root, Thu Jun 25 15:20:11 2015 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.176 by root, Sun Jan 10 23:05:11 2010 UTC vs.
Revision 1.255 by root, Thu Jun 25 15:20:11 2015 UTC