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Revision 1.181 by root, Tue May 4 21:14:01 2010 UTC vs.
Revision 1.279 by root, Sat Jan 6 01:04:42 2018 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '3.65';	176	our $VERSION = 4.4;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	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	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		182	aio_pathsync aio_readahead aio_fiemap aio_allocate
179	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
181	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
182	aio_msync aio_mtouch aio_statvfs);	186	aio_msync aio_mtouch aio_mlock aio_mlockall
		187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
183		190
184	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
185	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
186	min_parallel max_parallel max_idle	193	min_parallel max_parallel max_idle idle_timeout
187	nreqs nready npending nthreads	194	nreqs nready npending nthreads
188	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
189	sendfile fadvise);	196	sendfile fadvise madvise
		197	mmap munmap munlock munlockall);
190		198
191	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
192		200
193	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
194		202
…		…
198		206
199	=head1 FUNCTIONS	207	=head1 FUNCTIONS
200		208
201	=head2 QUICK OVERVIEW	209	=head2 QUICK OVERVIEW
202		210
203	This section simply lists the prototypes of the most important functions	211	This section simply lists the prototypes most of the functions for
204	for quick reference. See the following sections for function-by-function	212	quick reference. See the following sections for function-by-function
205	documentation.	213	documentation.
206		214
		215	aio_wd $pathname, $callback->($wd)
207	aio_open $pathname, $flags, $mode, $callback->($fh)	216	aio_open $pathname, $flags, $mode, $callback->($fh)
208	aio_close $fh, $callback->($status)	217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
209	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
210	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
211	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
212	aio_readahead $fh,$offset,$length, $callback->($retval)	222	aio_readahead $fh,$offset,$length, $callback->($retval)
213	aio_stat $fh_or_path, $callback->($status)	223	aio_stat $fh_or_path, $callback->($status)
214	aio_lstat $fh, $callback->($status)	224	aio_lstat $fh, $callback->($status)
215	aio_statvfs $fh_or_path, $callback->($statvfs)	225	aio_statvfs $fh_or_path, $callback->($statvfs)
216	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
217	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	227	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		228	aio_chmod $fh_or_path, $mode, $callback->($status)
218	aio_truncate $fh_or_path, $offset, $callback->($status)	229	aio_truncate $fh_or_path, $offset, $callback->($status)
219	aio_chmod $fh_or_path, $mode, $callback->($status)	230	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		231	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
220	aio_unlink $pathname, $callback->($status)	232	aio_unlink $pathname, $callback->($status)
221	aio_mknod $path, $mode, $dev, $callback->($status)	233	aio_mknod $pathname, $mode, $dev, $callback->($status)
222	aio_link $srcpath, $dstpath, $callback->($status)	234	aio_link $srcpath, $dstpath, $callback->($status)
223	aio_symlink $srcpath, $dstpath, $callback->($status)	235	aio_symlink $srcpath, $dstpath, $callback->($status)
224	aio_readlink $path, $callback->($link)	236	aio_readlink $pathname, $callback->($link)
		237	aio_realpath $pathname, $callback->($path)
225	aio_rename $srcpath, $dstpath, $callback->($status)	238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
226	aio_mkdir $pathname, $mode, $callback->($status)	240	aio_mkdir $pathname, $mode, $callback->($status)
227	aio_rmdir $pathname, $callback->($status)	241	aio_rmdir $pathname, $callback->($status)
228	aio_readdir $pathname, $callback->($entries)	242	aio_readdir $pathname, $callback->($entries)
229	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
230	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
231	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	245	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		246	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
232	aio_load $path, $data, $callback->($status)	247	aio_load $pathname, $data, $callback->($status)
233	aio_copy $srcpath, $dstpath, $callback->($status)	248	aio_copy $srcpath, $dstpath, $callback->($status)
234	aio_move $srcpath, $dstpath, $callback->($status)	249	aio_move $srcpath, $dstpath, $callback->($status)
235	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
236	aio_rmtree $path, $callback->($status)	250	aio_rmtree $pathname, $callback->($status)
		251	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		252	aio_ioctl $fh, $request, $buf, $callback->($status)
237	aio_sync $callback->($status)	253	aio_sync $callback->($status)
		254	aio_syncfs $fh, $callback->($status)
238	aio_fsync $fh, $callback->($status)	255	aio_fsync $fh, $callback->($status)
239	aio_fdatasync $fh, $callback->($status)	256	aio_fdatasync $fh, $callback->($status)
240	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
241	aio_pathsync $path, $callback->($status)	258	aio_pathsync $pathname, $callback->($status)
242	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
243	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		262	aio_mlockall $flags, $callback->($status)
244	aio_group $callback->(...)	263	aio_group $callback->(...)
245	aio_nop $callback->()	264	aio_nop $callback->()
246		265
247	$prev_pri = aioreq_pri [$pri]	266	$prev_pri = aioreq_pri [$pri]
248	aioreq_nice $pri_adjust	267	aioreq_nice $pri_adjust
…		…
254	IO::AIO::max_poll_reqs $nreqs	273	IO::AIO::max_poll_reqs $nreqs
255	IO::AIO::max_poll_time $seconds	274	IO::AIO::max_poll_time $seconds
256	IO::AIO::min_parallel $nthreads	275	IO::AIO::min_parallel $nthreads
257	IO::AIO::max_parallel $nthreads	276	IO::AIO::max_parallel $nthreads
258	IO::AIO::max_idle $nthreads	277	IO::AIO::max_idle $nthreads
		278	IO::AIO::idle_timeout $seconds
259	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
260	IO::AIO::nreqs	280	IO::AIO::nreqs
261	IO::AIO::nready	281	IO::AIO::nready
262	IO::AIO::npending	282	IO::AIO::npending
		283	$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
		284	IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
263		285
264	IO::AIO::sendfile $ofh, $ifh, $offset, $count	286	IO::AIO::sendfile $ofh, $ifh, $offset, $count
265	IO::AIO::fadvise $fh, $offset, $len, $advice	287	IO::AIO::fadvise $fh, $offset, $len, $advice
266	IO::AIO::mlockall $flags	288	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		289	IO::AIO::munmap $scalar
		290	IO::AIO::madvise $scalar, $offset, $length, $advice
		291	IO::AIO::mprotect $scalar, $offset, $length, $protect
		292	IO::AIO::munlock $scalar, $offset = 0, $length = undef
267	IO::AIO::munlockall	293	IO::AIO::munlockall
268		294
269	=head2 AIO REQUEST FUNCTIONS	295	=head2 API NOTES
270		296
271	All the C<aio_*> calls are more or less thin wrappers around the syscall	297	All the C<aio_*> calls are more or less thin wrappers around the syscall
272	with the same name (sans C<aio_>). The arguments are similar or identical,	298	with the same name (sans C<aio_>). The arguments are similar or identical,
273	and they all accept an additional (and optional) C<$callback> argument	299	and they all accept an additional (and optional) C<$callback> argument
274	which must be a code reference. This code reference will get called with	300	which must be a code reference. This code reference will be called after
275	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	301	the syscall has been executed in an asynchronous fashion. The results
276	perl, which usually delivers "false") as its sole argument after the given	302	of the request will be passed as arguments to the callback (and, if an
277	syscall has been executed asynchronously.	303	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		304	most syscalls return C<-1> on error, unlike perl, which usually delivers
		305	"false").
		306
		307	Some requests (such as C<aio_readdir>) pass the actual results and
		308	communicate failures by passing C<undef>.
278		309
279	All functions expecting a filehandle keep a copy of the filehandle	310	All functions expecting a filehandle keep a copy of the filehandle
280	internally until the request has finished.	311	internally until the request has finished.
281		312
282	All functions return request objects of type L<IO::AIO::REQ> that allow	313	All functions return request objects of type L<IO::AIO::REQ> that allow
283	further manipulation of those requests while they are in-flight.	314	further manipulation of those requests while they are in-flight.
284		315
285	The pathnames you pass to these routines I<must> be absolute and	316	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	317	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	318	current working directory could have changed. Alternatively, you can
288	changed. Alternatively, you can make sure that you never change the	319	make sure that you never change the current working directory anywhere
289	current working directory anywhere in the program and then use relative	320	in the program and then use relative paths. You can also take advantage
290	paths.	321	of IO::AIOs working directory abstraction, that lets you specify paths
		322	relative to some previously-opened "working directory object" - see the
		323	description of the C<IO::AIO::WD> class later in this document.
291		324
292	To encode pathnames as octets, either make sure you either: a) always pass	325	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	326	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	327	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	328	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)	329	effect in the user environment, d) use Glib::filename_from_unicode on
297	use something else to ensure your scalar has the correct contents.	330	unicode filenames or e) use something else to ensure your scalar has the
		331	correct contents.
298		332
299	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	333	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
300	handles correctly whether it is set or not.	334	handles correctly whether it is set or not.
		335
		336	=head2 AIO REQUEST FUNCTIONS
301		337
302	=over 4	338	=over 4
303		339
304	=item $prev_pri = aioreq_pri [$pri]	340	=item $prev_pri = aioreq_pri [$pri]
305		341
…		…
335		371
336		372
337	=item aio_open $pathname, $flags, $mode, $callback->($fh)	373	=item aio_open $pathname, $flags, $mode, $callback->($fh)
338		374
339	Asynchronously open or create a file and call the callback with a newly	375	Asynchronously open or create a file and call the callback with a newly
340	created filehandle for the file.	376	created filehandle for the file (or C<undef> in case of an error).
341		377
342	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	378	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
343	for an explanation.	379	for an explanation.
344		380
345	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	381	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
361	} else {	397	} else {
362	die "open failed: $!\n";	398	die "open failed: $!\n";
363	}	399	}
364	};	400	};
365		401
		402	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		403	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		404	following POSIX and non-POSIX constants are available (missing ones on
		405	your system are, as usual, C<0>):
		406
		407	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		408	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		409	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		410
366		411
367	=item aio_close $fh, $callback->($status)	412	=item aio_close $fh, $callback->($status)
368		413
369	Asynchronously close a file and call the callback with the result	414	Asynchronously close a file and call the callback with the result
370	code.	415	code.
…		…
379	Or in other words: the file descriptor will be closed, but it will not be	424	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.	425	free for reuse until the perl filehandle is closed.
381		426
382	=cut	427	=cut
383		428
		429	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		430
		431	Seeks the filehandle to the new C<$offset>, similarly to perl's
		432	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		433	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		434	C<IO::AIO::SEEK_END>).
		435
		436	The resulting absolute offset will be passed to the callback, or C<-1> in
		437	case of an error.
		438
		439	In theory, the C<$whence> constants could be different than the
		440	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		441	so don't panic.
		442
		443	As a GNU/Linux (and maybe Solaris) extension, also the constants
		444	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		445	could be found. No guarantees about suitability for use in C<aio_seek> or
		446	Perl's C<sysseek> can be made though, although I would naively assume they
		447	"just work".
		448
384	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	449	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
385		450
386	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	451	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
387		452
388	Reads or writes C<$length> bytes from or to the specified C<$fh> and	453	Reads or writes C<$length> bytes from or to the specified C<$fh> and
389	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	454	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
390	and calls the callback without the actual number of bytes read (or -1 on	455	calls the callback with the actual number of bytes transferred (or -1 on
391	error, just like the syscall).	456	error, just like the syscall).
392		457
393	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	458	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
394	offset plus the actual number of bytes read.	459	offset plus the actual number of bytes read.
395		460
…		…
420		485
421	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	486	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
422	reading at byte offset C<$in_offset>, and starts writing at the current	487	reading at byte offset C<$in_offset>, and starts writing at the current
423	file offset of C<$out_fh>. Because of that, it is not safe to issue more	488	file offset of C<$out_fh>. Because of that, it is not safe to issue more
424	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	489	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
425	other.	490	other. The same C<$in_fh> works fine though, as this function does not
		491	move or use the file offset of C<$in_fh>.
426		492
		493	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		494	are written, and there is no way to find out how many more bytes have been
		495	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		496	number of bytes written to C<$out_fh>. Only if the result value equals
		497	C<$length> one can assume that C<$length> bytes have been read.
		498
		499	Unlike with other C<aio_> functions, it makes a lot of sense to use
		500	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		501	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		502	the socket I/O will be non-blocking. Note, however, that you can run
		503	into a trap where C<aio_sendfile> reads some data with readahead, then
		504	fails to write all data, and when the socket is ready the next time, the
		505	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		506	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		507	resource usage.
		508
427	This call tries to make use of a native C<sendfile> syscall to provide	509	This call tries to make use of a native C<sendfile>-like syscall to
428	zero-copy operation. For this to work, C<$out_fh> should refer to a	510	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.	511	a socket, and C<$in_fh> should refer to an mmap'able file.
430		512
431	If a native sendfile cannot be found or it fails with C<ENOSYS>,	513	If a native sendfile cannot be found or it fails with C<ENOSYS>,
432	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	514	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
433	it will be emulated, so you can call C<aio_sendfile> on any type of	515	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
434	filehandle regardless of the limitations of the operating system.	516	type of filehandle regardless of the limitations of the operating system.
435		517
436	Please note, however, that C<aio_sendfile> can read more bytes from	518	As native sendfile syscalls (as practically any non-POSIX interface hacked
437	C<$in_fh> than are written, and there is no way to find out how many	519	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	520	on many systems, this implementation tries to work around some known bugs
439	provides the number of bytes written to C<$out_fh>. Only if the result	521	in Linux and FreeBSD kernels (probably others, too), but that might fail,
440	value equals C<$length> one can assume that C<$length> bytes have been	522	so you really really should check the return value of C<aio_sendfile> -
441	read.	523	fewer bytes than expected might have been transferred.
442		524
443		525
444	=item aio_readahead $fh,$offset,$length, $callback->($retval)	526	=item aio_readahead $fh,$offset,$length, $callback->($retval)
445		527
446	C<aio_readahead> populates the page cache with data from a file so that	528	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	532	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	533	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	534	(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.	535	file. The current file offset of the file is left unchanged.
454		536
455	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	537	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.	538	be emulated by simply reading the data, which would have a similar effect.
457		539
458		540
459	=item aio_stat $fh_or_path, $callback->($status)	541	=item aio_stat $fh_or_path, $callback->($status)
460		542
461	=item aio_lstat $fh, $callback->($status)	543	=item aio_lstat $fh, $callback->($status)
…		…
468	for an explanation.	550	for an explanation.
469		551
470	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	552	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	553	error when stat'ing a large file, the results will be silently truncated
472	unless perl itself is compiled with large file support.	554	unless perl itself is compiled with large file support.
		555
		556	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		557	following constants and functions (if not implemented, the constants will
		558	be C<0> and the functions will either C<croak> or fall back on traditional
		559	behaviour).
		560
		561	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		562	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		563	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
473		564
474	Example: Print the length of F</etc/passwd>:	565	Example: Print the length of F</etc/passwd>:
475		566
476	aio_stat "/etc/passwd", sub {	567	aio_stat "/etc/passwd", sub {
477	$_[0] and die "stat failed: $!";	568	$_[0] and die "stat failed: $!";
…		…
521	namemax => 255,	612	namemax => 255,
522	frsize => 1024,	613	frsize => 1024,
523	fsid => 1810	614	fsid => 1810
524	}	615	}
525		616
		617	Here is a (likely partial - send me updates!) list of fsid values used by
		618	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		619
		620	0x0000adf5 adfs
		621	0x0000adff affs
		622	0x5346414f afs
		623	0x09041934 anon-inode filesystem
		624	0x00000187 autofs
		625	0x42465331 befs
		626	0x1badface bfs
		627	0x42494e4d binfmt_misc
		628	0x9123683e btrfs
		629	0x0027e0eb cgroupfs
		630	0xff534d42 cifs
		631	0x73757245 coda
		632	0x012ff7b7 coh
		633	0x28cd3d45 cramfs
		634	0x453dcd28 cramfs-wend (wrong endianness)
		635	0x64626720 debugfs
		636	0x00001373 devfs
		637	0x00001cd1 devpts
		638	0x0000f15f ecryptfs
		639	0x00414a53 efs
		640	0x0000137d ext
		641	0x0000ef53 ext2/ext3/ext4
		642	0x0000ef51 ext2
		643	0xf2f52010 f2fs
		644	0x00004006 fat
		645	0x65735546 fuseblk
		646	0x65735543 fusectl
		647	0x0bad1dea futexfs
		648	0x01161970 gfs2
		649	0x47504653 gpfs
		650	0x00004244 hfs
		651	0xf995e849 hpfs
		652	0x00c0ffee hostfs
		653	0x958458f6 hugetlbfs
		654	0x2bad1dea inotifyfs
		655	0x00009660 isofs
		656	0x000072b6 jffs2
		657	0x3153464a jfs
		658	0x6b414653 k-afs
		659	0x0bd00bd0 lustre
		660	0x0000137f minix
		661	0x0000138f minix 30 char names
		662	0x00002468 minix v2
		663	0x00002478 minix v2 30 char names
		664	0x00004d5a minix v3
		665	0x19800202 mqueue
		666	0x00004d44 msdos
		667	0x0000564c novell
		668	0x00006969 nfs
		669	0x6e667364 nfsd
		670	0x00003434 nilfs
		671	0x5346544e ntfs
		672	0x00009fa1 openprom
		673	0x7461636F ocfs2
		674	0x00009fa0 proc
		675	0x6165676c pstorefs
		676	0x0000002f qnx4
		677	0x68191122 qnx6
		678	0x858458f6 ramfs
		679	0x52654973 reiserfs
		680	0x00007275 romfs
		681	0x67596969 rpc_pipefs
		682	0x73636673 securityfs
		683	0xf97cff8c selinux
		684	0x0000517b smb
		685	0x534f434b sockfs
		686	0x73717368 squashfs
		687	0x62656572 sysfs
		688	0x012ff7b6 sysv2
		689	0x012ff7b5 sysv4
		690	0x01021994 tmpfs
		691	0x15013346 udf
		692	0x00011954 ufs
		693	0x54190100 ufs byteswapped
		694	0x00009fa2 usbdevfs
		695	0x01021997 v9fs
		696	0xa501fcf5 vxfs
		697	0xabba1974 xenfs
		698	0x012ff7b4 xenix
		699	0x58465342 xfs
		700	0x012fd16d xia
526		701
527	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	702	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
528		703
529	Works like perl's C<utime> function (including the special case of $atime	704	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	705	and $mtime being undef). Fractional times are supported if the underlying
…		…
558	=item aio_truncate $fh_or_path, $offset, $callback->($status)	733	=item aio_truncate $fh_or_path, $offset, $callback->($status)
559		734
560	Works like truncate(2) or ftruncate(2).	735	Works like truncate(2) or ftruncate(2).
561		736
562		737
		738	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		739
		740	Allocates or frees disk space according to the C<$mode> argument. See the
		741	linux C<fallocate> documentation for details.
		742
		743	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		744	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		745	to deallocate a file range.
		746
		747	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		748	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		749	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		750	to unshare shared blocks (see your L<fallocate(2)> manpage).
		751
		752	The file system block size used by C<fallocate> is presumably the
		753	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		754	can dictate other limitations.
		755
		756	If C<fallocate> isn't available or cannot be emulated (currently no
		757	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		758
		759
563	=item aio_chmod $fh_or_path, $mode, $callback->($status)	760	=item aio_chmod $fh_or_path, $mode, $callback->($status)
564		761
565	Works like perl's C<chmod> function.	762	Works like perl's C<chmod> function.
566		763
567		764
…		…
569		766
570	Asynchronously unlink (delete) a file and call the callback with the	767	Asynchronously unlink (delete) a file and call the callback with the
571	result code.	768	result code.
572		769
573		770
574	=item aio_mknod $path, $mode, $dev, $callback->($status)	771	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
575		772
576	[EXPERIMENTAL]	773	[EXPERIMENTAL]
577		774
578	Asynchronously create a device node (or fifo). See mknod(2).	775	Asynchronously create a device node (or fifo). See mknod(2).
579		776
580	The only (POSIX-) portable way of calling this function is:	777	The only (POSIX-) portable way of calling this function is:
581		778
582	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	779	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
583		780
		781	See C<aio_stat> for info about some potentially helpful extra constants
		782	and functions.
584		783
585	=item aio_link $srcpath, $dstpath, $callback->($status)	784	=item aio_link $srcpath, $dstpath, $callback->($status)
586		785
587	Asynchronously create a new link to the existing object at C<$srcpath> at	786	Asynchronously create a new link to the existing object at C<$srcpath> at
588	the path C<$dstpath> and call the callback with the result code.	787	the path C<$dstpath> and call the callback with the result code.
…		…
592		791
593	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	792	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
594	the path C<$dstpath> and call the callback with the result code.	793	the path C<$dstpath> and call the callback with the result code.
595		794
596		795
597	=item aio_readlink $path, $callback->($link)	796	=item aio_readlink $pathname, $callback->($link)
598		797
599	Asynchronously read the symlink specified by C<$path> and pass it to	798	Asynchronously read the symlink specified by C<$path> and pass it to
600	the callback. If an error occurs, nothing or undef gets passed to the	799	the callback. If an error occurs, nothing or undef gets passed to the
601	callback.	800	callback.
602		801
603		802
		803	=item aio_realpath $pathname, $callback->($path)
		804
		805	Asynchronously make the path absolute and resolve any symlinks in
		806	C<$path>. The resulting path only consists of directories (same as
		807	L<Cwd::realpath>).
		808
		809	This request can be used to get the absolute path of the current working
		810	directory by passing it a path of F<.> (a single dot).
		811
		812
604	=item aio_rename $srcpath, $dstpath, $callback->($status)	813	=item aio_rename $srcpath, $dstpath, $callback->($status)
605		814
606	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	815	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
607	rename(2) and call the callback with the result code.	816	rename(2) and call the callback with the result code.
		817
		818	On systems that support the AIO::WD working directory abstraction
		819	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		820	of failing, C<rename> is called on the absolute path of C<$wd>.
		821
		822
		823	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		824
		825	Basically a version of C<aio_rename> with an additional C<$flags>
		826	argument. Calling this with C<$flags=0> is the same as calling
		827	C<aio_rename>.
		828
		829	Non-zero flags are currently only supported on GNU/Linux systems that
		830	support renameat2. Other systems fail with C<ENOSYS> in this case.
		831
		832	The following constants are available (missing ones are, as usual C<0>),
		833	see renameat2(2) for details:
		834
		835	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		836	and C<IO::AIO::RENAME_WHITEOUT>.
608		837
609		838
610	=item aio_mkdir $pathname, $mode, $callback->($status)	839	=item aio_mkdir $pathname, $mode, $callback->($status)
611		840
612	Asynchronously mkdir (create) a directory and call the callback with	841	Asynchronously mkdir (create) a directory and call the callback with
…		…
617	=item aio_rmdir $pathname, $callback->($status)	846	=item aio_rmdir $pathname, $callback->($status)
618		847
619	Asynchronously rmdir (delete) a directory and call the callback with the	848	Asynchronously rmdir (delete) a directory and call the callback with the
620	result code.	849	result code.
621		850
		851	On systems that support the AIO::WD working directory abstraction
		852	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		853	C<rmdir> is called on the absolute path of C<$wd>.
		854
622		855
623	=item aio_readdir $pathname, $callback->($entries)	856	=item aio_readdir $pathname, $callback->($entries)
624		857
625	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	858	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	859	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
630	array-ref with the filenames.	863	array-ref with the filenames.
631		864
632		865
633	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	866	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
634		867
635	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	868	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	869	tune behaviour and output format. In case of an error, C<$entries> will be
637	C<undef>.	870	C<undef>.
638		871
639	The flags are a combination of the following constants, ORed together (the	872	The flags are a combination of the following constants, ORed together (the
640	flags will also be passed to the callback, possibly modified):	873	flags will also be passed to the callback, possibly modified):
641		874
642	=over 4	875	=over 4
643		876
644	=item IO::AIO::READDIR_DENTS	877	=item IO::AIO::READDIR_DENTS
645		878
646	When this flag is off, then the callback gets an arrayref with of names	879	When this flag is off, then the callback gets an arrayref consisting of
647	only (as with C<aio_readdir>), otherwise it gets an arrayref with	880	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
648	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	881	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
649	entry in more detail.	882	entry in more detail.
650		883
651	C<$name> is the name of the entry.	884	C<$name> is the name of the entry.
652		885
…		…
665	systems that do not deliver the inode information.	898	systems that do not deliver the inode information.
666		899
667	=item IO::AIO::READDIR_DIRS_FIRST	900	=item IO::AIO::READDIR_DIRS_FIRST
668		901
669	When this flag is set, then the names will be returned in an order where	902	When this flag is set, then the names will be returned in an order where
670	likely directories come first. This is useful when you need to quickly	903	likely directories come first, in optimal stat order. This is useful when
671	find directories, or you want to find all directories while avoiding to	904	you need to quickly find directories, or you want to find all directories
672	stat() each entry.	905	while avoiding to stat() each entry.
673		906
674	If the system returns type information in readdir, then this is used	907	If the system returns type information in readdir, then this is used
675	to find directories directly. Otherwise, likely directories are files	908	to find directories directly. Otherwise, likely directories are names
676	beginning with ".", or otherwise files with no dots, of which files with	909	beginning with ".", or otherwise names with no dots, of which names with
677	short names are tried first.	910	short names are tried first.
678		911
679	=item IO::AIO::READDIR_STAT_ORDER	912	=item IO::AIO::READDIR_STAT_ORDER
680		913
681	When this flag is set, then the names will be returned in an order	914	When this flag is set, then the names will be returned in an order
…		…
688		921
689	=item IO::AIO::READDIR_FOUND_UNKNOWN	922	=item IO::AIO::READDIR_FOUND_UNKNOWN
690		923
691	This flag should not be set when calling C<aio_readdirx>. Instead, it	924	This flag should not be set when calling C<aio_readdirx>. Instead, it
692	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	925	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
693	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	926	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
694	C<$type>'s are known, which can be used to speed up some algorithms.	927	C<$type>'s are known, which can be used to speed up some algorithms.
695		928
696	=back	929	=back
697		930
698		931
		932	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		933
		934	Opens, reads and closes the given file. The data is put into C<$data>,
		935	which is resized as required.
		936
		937	If C<$offset> is negative, then it is counted from the end of the file.
		938
		939	If C<$length> is zero, then the remaining length of the file is
		940	used. Also, in this case, the same limitations to modifying C<$data> apply
		941	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		942	with C<substr>. If the size of the file is known, specifying a non-zero
		943	C<$length> results in a performance advantage.
		944
		945	This request is similar to the older C<aio_load> request, but since it is
		946	a single request, it might be more efficient to use.
		947
		948	Example: load F</etc/passwd> into C<$passwd>.
		949
		950	my $passwd;
		951	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		952	$_[0] >= 0
		953	or die "/etc/passwd: $!\n";
		954
		955	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		956	print $passwd;
		957	};
		958	IO::AIO::flush;
		959
		960
699	=item aio_load $path, $data, $callback->($status)	961	=item aio_load $pathname, $data, $callback->($status)
700		962
701	This is a composite request that tries to fully load the given file into	963	This is a composite request that tries to fully load the given file into
702	memory. Status is the same as with aio_read.	964	memory. Status is the same as with aio_read.
		965
		966	Using C<aio_slurp> might be more efficient, as it is a single request.
703		967
704	=cut	968	=cut
705		969
706	sub aio_load($$;$) {	970	sub aio_load($$;$) {
707	my ($path, undef, $cb) = @_;	971	my ($path, undef, $cb) = @_;
…		…
727	=item aio_copy $srcpath, $dstpath, $callback->($status)	991	=item aio_copy $srcpath, $dstpath, $callback->($status)
728		992
729	Try to copy the I<file> (directories not supported as either source or	993	Try to copy the I<file> (directories not supported as either source or
730	destination) from C<$srcpath> to C<$dstpath> and call the callback with	994	destination) from C<$srcpath> to C<$dstpath> and call the callback with
731	a status of C<0> (ok) or C<-1> (error, see C<$!>).	995	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		996
		997	Existing destination files will be truncated.
732		998
733	This is a composite request that creates the destination file with	999	This is a composite request that creates the destination file with
734	mode 0200 and copies the contents of the source file into it using	1000	mode 0200 and copies the contents of the source file into it using
735	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	1001	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
736	uid/gid, in that order.	1002	uid/gid, in that order.
…		…
826	if ($_[0] && $! == EXDEV) {	1092	if ($_[0] && $! == EXDEV) {
827	aioreq_pri $pri;	1093	aioreq_pri $pri;
828	add $grp aio_copy $src, $dst, sub {	1094	add $grp aio_copy $src, $dst, sub {
829	$grp->result ($_[0]);	1095	$grp->result ($_[0]);
830		1096
831	if (!$_[0]) {	1097	unless ($_[0]) {
832	aioreq_pri $pri;	1098	aioreq_pri $pri;
833	add $grp aio_unlink $src;	1099	add $grp aio_unlink $src;
834	}	1100	}
835	};	1101	};
836	} else {	1102	} else {
…		…
839	};	1105	};
840		1106
841	$grp	1107	$grp
842	}	1108	}
843		1109
844	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1110	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
845		1111
846	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1112	Scans a directory (similar to C<aio_readdir>) but additionally tries to
847	efficiently separate the entries of directory C<$path> into two sets of	1113	efficiently separate the entries of directory C<$path> into two sets of
848	names, directories you can recurse into (directories), and ones you cannot	1114	names, directories you can recurse into (directories), and ones you cannot
849	recurse into (everything else, including symlinks to directories).	1115	recurse into (everything else, including symlinks to directories).
850		1116
851	C<aio_scandir> is a composite request that creates of many sub requests_	1117	C<aio_scandir> is a composite request that generates many sub requests.
852	C<$maxreq> specifies the maximum number of outstanding aio requests that	1118	C<$maxreq> specifies the maximum number of outstanding aio requests that
853	this function generates. If it is C<< <= 0 >>, then a suitable default	1119	this function generates. If it is C<< <= 0 >>, then a suitable default
854	will be chosen (currently 4).	1120	will be chosen (currently 4).
855		1121
856	On error, the callback is called without arguments, otherwise it receives	1122	On error, the callback is called without arguments, otherwise it receives
…		…
880	Then entries will be sorted into likely directories a non-initial dot	1146	Then entries will be sorted into likely directories a non-initial dot
881	currently) and likely non-directories (see C<aio_readdirx>). Then every	1147	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,	1148	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	1149	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	1150	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	1151	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	1152	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	1153	data (e.g. ext2fs filetype feature), even on systems that cannot return
888	the filetype information on readdir.	1154	the filetype information on readdir.
889		1155
890	If the known number of directories (link count - 2) has been reached, the	1156	If the known number of directories (link count - 2) has been reached, the
…		…
906		1172
907	my $grp = aio_group $cb;	1173	my $grp = aio_group $cb;
908		1174
909	$maxreq = 4 if $maxreq <= 0;	1175	$maxreq = 4 if $maxreq <= 0;
910		1176
911	# stat once	1177	# get a wd object
912	aioreq_pri $pri;	1178	aioreq_pri $pri;
913	add $grp aio_stat $path, sub {	1179	add $grp aio_wd $path, sub {
		1180	$_[0]
914	return $grp->result () if $_[0];	1181	or return $grp->result ();
915	my $now = time;
916	my $hash1 = join ":", (stat _)[0,1,3,7,9];
917		1182
918	# read the directory entries	1183	my $wd = [shift, "."];
		1184
		1185	# stat once
919	aioreq_pri $pri;	1186	aioreq_pri $pri;
920	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1187	add $grp aio_stat $wd, sub {
921	my $entries = shift
922	or return $grp->result ();	1188	return $grp->result () if $_[0];
		1189	my $now = time;
		1190	my $hash1 = join ":", (stat _)[0,1,3,7,9];
923		1191
924	# stat the dir another time	1192	# read the directory entries
925	aioreq_pri $pri;	1193	aioreq_pri $pri;
		1194	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1195	my $entries = shift
		1196	or return $grp->result ();
		1197
		1198	# stat the dir another time
		1199	aioreq_pri $pri;
926	add $grp aio_stat $path, sub {	1200	add $grp aio_stat $wd, sub {
927	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1201	my $hash2 = join ":", (stat _)[0,1,3,7,9];
928		1202
929	my $ndirs;	1203	my $ndirs;
930		1204
931	# take the slow route if anything looks fishy	1205	# take the slow route if anything looks fishy
932	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1206	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
933	$ndirs = -1;	1207	$ndirs = -1;
934	} else {	1208	} else {
935	# if nlink == 2, we are finished	1209	# if nlink == 2, we are finished
936	# for non-posix-fs's, we rely on nlink < 2	1210	# for non-posix-fs's, we rely on nlink < 2
937	$ndirs = (stat _)[3] - 2	1211	$ndirs = (stat _)[3] - 2
938	or return $grp->result ([], $entries);	1212	or return $grp->result ([], $entries);
939	}	1213	}
940		1214
941	my (@dirs, @nondirs);	1215	my (@dirs, @nondirs);
942		1216
943	my $statgrp = add $grp aio_group sub {	1217	my $statgrp = add $grp aio_group sub {
944	$grp->result (\@dirs, \@nondirs);	1218	$grp->result (\@dirs, \@nondirs);
945	};	1219	};
946		1220
947	limit $statgrp $maxreq;	1221	limit $statgrp $maxreq;
948	feed $statgrp sub {	1222	feed $statgrp sub {
949	return unless @$entries;	1223	return unless @$entries;
950	my $entry = shift @$entries;	1224	my $entry = shift @$entries;
951		1225
952	aioreq_pri $pri;	1226	aioreq_pri $pri;
		1227	$wd->[1] = "$entry/.";
953	add $statgrp aio_stat "$path/$entry/.", sub {	1228	add $statgrp aio_stat $wd, sub {
954	if ($_[0] < 0) {	1229	if ($_[0] < 0) {
955	push @nondirs, $entry;	1230	push @nondirs, $entry;
956	} else {	1231	} else {
957	# need to check for real directory	1232	# need to check for real directory
958	aioreq_pri $pri;	1233	aioreq_pri $pri;
		1234	$wd->[1] = $entry;
959	add $statgrp aio_lstat "$path/$entry", sub {	1235	add $statgrp aio_lstat $wd, sub {
960	if (-d _) {	1236	if (-d _) {
961	push @dirs, $entry;	1237	push @dirs, $entry;
962		1238
963	unless (--$ndirs) {	1239	unless (--$ndirs) {
964	push @nondirs, @$entries;	1240	push @nondirs, @$entries;
965	feed $statgrp;	1241	feed $statgrp;
		1242	}
		1243	} else {
		1244	push @nondirs, $entry;
966	}	1245	}
967	} else {
968	push @nondirs, $entry;
969	}	1246	}
970	}	1247	}
971	}	1248	};
972	};	1249	};
973	};	1250	};
974	};	1251	};
975	};	1252	};
976	};	1253	};
977		1254
978	$grp	1255	$grp
979	}	1256	}
980		1257
981	=item aio_rmtree $path, $callback->($status)	1258	=item aio_rmtree $pathname, $callback->($status)
982		1259
983	Delete a directory tree starting (and including) C<$path>, return the	1260	Delete a directory tree starting (and including) C<$path>, return the
984	status of the final C<rmdir> only. This is a composite request that	1261	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	1262	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
986	everything else.	1263	everything else.
987		1264
988	=cut	1265	=cut
989		1266
…		…
1011	};	1288	};
1012		1289
1013	$grp	1290	$grp
1014	}	1291	}
1015		1292
		1293	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1294
		1295	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1296
		1297	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1298	they execute asynchronously and pass the return value to the callback.
		1299
		1300	Both calls can be used for a lot of things, some of which make more sense
		1301	to run asynchronously in their own thread, while some others make less
		1302	sense. For example, calls that block waiting for external events, such
		1303	as locking, will also lock down an I/O thread while it is waiting, which
		1304	can deadlock the whole I/O system. At the same time, there might be no
		1305	alternative to using a thread to wait.
		1306
		1307	So in general, you should only use these calls for things that do
		1308	(filesystem) I/O, not for things that wait for other events (network,
		1309	other processes), although if you are careful and know what you are doing,
		1310	you still can.
		1311
		1312	The following constants are available (missing ones are, as usual C<0>):
		1313
		1314	C<F_DUPFD_CLOEXEC>,
		1315
		1316	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1317
		1318	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1319
		1320	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1321	C<FS_IOC_FIEMAP>.
		1322
		1323	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1324	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1325
		1326	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1327	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1328	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1329	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1330	C<FS_FL_USER_MODIFIABLE>.
		1331
		1332	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1333	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1334	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1335	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1336
1016	=item aio_sync $callback->($status)	1337	=item aio_sync $callback->($status)
1017		1338
1018	Asynchronously call sync and call the callback when finished.	1339	Asynchronously call sync and call the callback when finished.
1019		1340
1020	=item aio_fsync $fh, $callback->($status)	1341	=item aio_fsync $fh, $callback->($status)
…		…
1027	Asynchronously call fdatasync on the given filehandle and call the	1348	Asynchronously call fdatasync on the given filehandle and call the
1028	callback with the fdatasync result code.	1349	callback with the fdatasync result code.
1029		1350
1030	If this call isn't available because your OS lacks it or it couldn't be	1351	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.	1352	detected, it will be emulated by calling C<fsync> instead.
		1353
		1354	=item aio_syncfs $fh, $callback->($status)
		1355
		1356	Asynchronously call the syncfs syscall to sync the filesystem associated
		1357	to the given filehandle and call the callback with the syncfs result
		1358	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1359	errno to C<ENOSYS> nevertheless.
1032		1360
1033	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1361	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1034		1362
1035	Sync the data portion of the file specified by C<$offset> and C<$length>	1363	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	1364	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1040	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1368	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1041	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1369	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1042	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1370	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1043	manpage for details.	1371	manpage for details.
1044		1372
1045	=item aio_pathsync $path, $callback->($status)	1373	=item aio_pathsync $pathname, $callback->($status)
1046		1374
1047	This request tries to open, fsync and close the given path. This is a	1375	This request tries to open, fsync and close the given path. This is a
1048	composite request intended to sync directories after directory operations	1376	composite request intended to sync directories after directory operations
1049	(E.g. rename). This might not work on all operating systems or have any	1377	(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	1378	specific effect, but usually it makes sure that directory changes get
…		…
1081	};	1409	};
1082		1410
1083	$grp	1411	$grp
1084	}	1412	}
1085		1413
1086	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1414	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1087		1415
1088	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1416	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1089	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1417	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1090	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1418	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1091	scalar must only be modified in-place while an aio operation is pending on	1419	scalar must only be modified in-place while an aio operation is pending on
…		…
1093		1421
1094	It calls the C<msync> function of your OS, if available, with the memory	1422	It calls the C<msync> function of your OS, if available, with the memory
1095	area starting at C<$offset> in the string and ending C<$length> bytes	1423	area starting at C<$offset> in the string and ending C<$length> bytes
1096	later. If C<$length> is negative, counts from the end, and if C<$length>	1424	later. If C<$length> is negative, counts from the end, and if C<$length>
1097	is C<undef>, then it goes till the end of the string. The flags can be	1425	is C<undef>, then it goes till the end of the string. The flags can be
1098	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1426	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1099	C<IO::AIO::MS_SYNC>.	1427	C<IO::AIO::MS_INVALIDATE>.
1100		1428
1101	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1429	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1102		1430
1103	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1431	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1104	scalars.	1432	scalars.
1105		1433
1106	It touches (reads or writes) all memory pages in the specified	1434	It touches (reads or writes) all memory pages in the specified
1107	range inside the scalar. All caveats and parameters are the same	1435	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	1436	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	1437	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	1438	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1111	writing an octet from it, which dirties the page).	1439	writing an octet from it, which dirties the page).
		1440
		1441	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1442
		1443	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1444	scalars.
		1445
		1446	It reads in all the pages of the underlying storage into memory (if any)
		1447	and locks them, so they are not getting swapped/paged out or removed.
		1448
		1449	If C<$length> is undefined, then the scalar will be locked till the end.
		1450
		1451	On systems that do not implement C<mlock>, this function returns C<-1>
		1452	and sets errno to C<ENOSYS>.
		1453
		1454	Note that the corresponding C<munlock> is synchronous and is
		1455	documented under L<MISCELLANEOUS FUNCTIONS>.
		1456
		1457	Example: open a file, mmap and mlock it - both will be undone when
		1458	C<$data> gets destroyed.
		1459
		1460	open my $fh, "<", $path or die "$path: $!";
		1461	my $data;
		1462	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1463	aio_mlock $data; # mlock in background
		1464
		1465	=item aio_mlockall $flags, $callback->($status)
		1466
		1467	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1468	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1469
		1470	On systems that do not implement C<mlockall>, this function returns C<-1>
		1471	and sets errno to C<ENOSYS>.
		1472
		1473	Note that the corresponding C<munlockall> is synchronous and is
		1474	documented under L<MISCELLANEOUS FUNCTIONS>.
		1475
		1476	Example: asynchronously lock all current and future pages into memory.
		1477
		1478	aio_mlockall IO::AIO::MCL_FUTURE;
		1479
		1480	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1481
		1482	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1483	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1484	the ioctl is not available on your OS, then this request will fail with
		1485	C<ENOSYS>.
		1486
		1487	C<$start> is the starting offset to query extents for, C<$length> is the
		1488	size of the range to query - if it is C<undef>, then the whole file will
		1489	be queried.
		1490
		1491	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1492	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1493	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1494	the data portion.
		1495
		1496	C<$count> is the maximum number of extent records to return. If it is
		1497	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1498	case, if it is C<0>, then the callback receives the number of extents
		1499	instead of the extents themselves (which is unreliable, see below).
		1500
		1501	If an error occurs, the callback receives no arguments. The special
		1502	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1503
		1504	Otherwise, the callback receives an array reference with extent
		1505	structures. Each extent structure is an array reference itself, with the
		1506	following members:
		1507
		1508	[$logical, $physical, $length, $flags]
		1509
		1510	Flags is any combination of the following flag values (typically either C<0>
		1511	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1512
		1513	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1514	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1515	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1516	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1517	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1518	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1519
		1520	At the time of this writing (Linux 3.2), this request is unreliable unless
		1521	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1522	it to return all extents of a range for files with a large number of
		1523	extents. The code (only) works around all these issues if C<$count> is
		1524	C<undef>.
1112		1525
1113	=item aio_group $callback->(...)	1526	=item aio_group $callback->(...)
1114		1527
1115	This is a very special aio request: Instead of doing something, it is a	1528	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	1529	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	1566	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	1567	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.	1568	except to put your application under artificial I/O pressure.
1156		1569
1157	=back	1570	=back
		1571
		1572
		1573	=head2 IO::AIO::WD - multiple working directories
		1574
		1575	Your process only has one current working directory, which is used by all
		1576	threads. This makes it hard to use relative paths (some other component
		1577	could call C<chdir> at any time, and it is hard to control when the path
		1578	will be used by IO::AIO).
		1579
		1580	One solution for this is to always use absolute paths. This usually works,
		1581	but can be quite slow (the kernel has to walk the whole path on every
		1582	access), and can also be a hassle to implement.
		1583
		1584	Newer POSIX systems have a number of functions (openat, fdopendir,
		1585	futimensat and so on) that make it possible to specify working directories
		1586	per operation.
		1587
		1588	For portability, and because the clowns who "designed", or shall I write,
		1589	perpetrated this new interface were obviously half-drunk, this abstraction
		1590	cannot be perfect, though.
		1591
		1592	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1593	object. This object stores the canonicalised, absolute version of the
		1594	path, and on systems that allow it, also a directory file descriptor.
		1595
		1596	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1597	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1598	object and a pathname instead (or the IO::AIO::WD object alone, which
		1599	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1600	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1601	to that IO::AIO::WD object.
		1602
		1603	For example, to get a wd object for F</etc> and then stat F<passwd>
		1604	inside, you would write:
		1605
		1606	aio_wd "/etc", sub {
		1607	my $etcdir = shift;
		1608
		1609	# although $etcdir can be undef on error, there is generally no reason
		1610	# to check for errors here, as aio_stat will fail with ENOENT
		1611	# when $etcdir is undef.
		1612
		1613	aio_stat [$etcdir, "passwd"], sub {
		1614	# yay
		1615	};
		1616	};
		1617
		1618	The fact that C<aio_wd> is a request and not a normal function shows that
		1619	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1620	which is why it is done asynchronously.
		1621
		1622	To stat the directory obtained with C<aio_wd> above, one could write
		1623	either of the following three request calls:
		1624
		1625	aio_lstat "/etc" , sub { ... # pathname as normal string
		1626	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1627	aio_lstat $wd , sub { ... # shorthand for the previous
		1628
		1629	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1630	object and the pathname string, so you could write the following without
		1631	causing any issues due to C<$path> getting reused:
		1632
		1633	my $path = [$wd, undef];
		1634
		1635	for my $name (qw(abc def ghi)) {
		1636	$path->[1] = $name;
		1637	aio_stat $path, sub {
		1638	# ...
		1639	};
		1640	}
		1641
		1642	There are some caveats: when directories get renamed (or deleted), the
		1643	pathname string doesn't change, so will point to the new directory (or
		1644	nowhere at all), while the directory fd, if available on the system,
		1645	will still point to the original directory. Most functions accepting a
		1646	pathname will use the directory fd on newer systems, and the string on
		1647	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1648	the string form of the pathname.
		1649
		1650	So this functionality is mainly useful to get some protection against
		1651	C<chdir>, to easily get an absolute path out of a relative path for future
		1652	reference, and to speed up doing many operations in the same directory
		1653	(e.g. when stat'ing all files in a directory).
		1654
		1655	The following functions implement this working directory abstraction:
		1656
		1657	=over 4
		1658
		1659	=item aio_wd $pathname, $callback->($wd)
		1660
		1661	Asynchonously canonicalise the given pathname and convert it to an
		1662	IO::AIO::WD object representing it. If possible and supported on the
		1663	system, also open a directory fd to speed up pathname resolution relative
		1664	to this working directory.
		1665
		1666	If something goes wrong, then C<undef> is passwd to the callback instead
		1667	of a working directory object and C<$!> is set appropriately. Since
		1668	passing C<undef> as working directory component of a pathname fails the
		1669	request with C<ENOENT>, there is often no need for error checking in the
		1670	C<aio_wd> callback, as future requests using the value will fail in the
		1671	expected way.
		1672
		1673	=item IO::AIO::CWD
		1674
		1675	This is a compiletime constant (object) that represents the process
		1676	current working directory.
		1677
		1678	Specifying this object as working directory object for a pathname is as if
		1679	the pathname would be specified directly, without a directory object. For
		1680	example, these calls are functionally identical:
		1681
		1682	aio_stat "somefile", sub { ... };
		1683	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1684
		1685	=back
		1686
		1687	To recover the path associated with an IO::AIO::WD object, you can use
		1688	C<aio_realpath>:
		1689
		1690	aio_realpath $wd, sub {
		1691	warn "path is $_[0]\n";
		1692	};
		1693
		1694	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1695	sometimes, fall back to using an absolue path.
1158		1696
1159	=head2 IO::AIO::REQ CLASS	1697	=head2 IO::AIO::REQ CLASS
1160		1698
1161	All non-aggregate C<aio_*> functions return an object of this class when	1699	All non-aggregate C<aio_*> functions return an object of this class when
1162	called in non-void context.	1700	called in non-void context.
…		…
1280		1818
1281	Sets a feeder/generator on this group: every group can have an attached	1819	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,	1820	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,	1821	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,	1822	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,	1823	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1286	delaying any later requests for a long time.	1824	requests, delaying any later requests for a long time.
1287		1825
1288	To avoid this, and allow incremental generation of requests, you can	1826	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	1827	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>,	1828	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	1829	below) requests active in the group itself and is expected to queue more
…		…
1340		1878
1341	See C<poll_cb> for an example.	1879	See C<poll_cb> for an example.
1342		1880
1343	=item IO::AIO::poll_cb	1881	=item IO::AIO::poll_cb
1344		1882
1345	Process some outstanding events on the result pipe. You have to call this	1883	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	1884	been executed but the results are not yet reported). You have to call
1347	returned earlier for whatever reason. Returns immediately when no events	1885	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		1886
		1887	Returns C<0> if all events could be processed (or there were no
		1888	events to process), or C<-1> if it returned earlier for whatever
		1889	reason. Returns immediately when no events are outstanding. The amount
		1890	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1891	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1892
1351	If not all requests were processed for whatever reason, the filehandle	1893	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	1894	descriptor will still be ready when C<poll_cb> returns, so normally you
1353	do anything special to have it called later.	1895	don't have to do anything special to have it called later.
		1896
		1897	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1898	ready, it can be beneficial to call this function from loops which submit
		1899	a lot of requests, to make sure the results get processed when they become
		1900	available and not just when the loop is finished and the event loop takes
		1901	over again. This function returns very fast when there are no outstanding
		1902	requests.
1354		1903
1355	Example: Install an Event watcher that automatically calls	1904	Example: Install an Event watcher that automatically calls
1356	IO::AIO::poll_cb with high priority (more examples can be found in the	1905	IO::AIO::poll_cb with high priority (more examples can be found in the
1357	SYNOPSIS section, at the top of this document):	1906	SYNOPSIS section, at the top of this document):
1358		1907
…		…
1360	poll => 'r', async => 1,	1909	poll => 'r', async => 1,
1361	cb => \&IO::AIO::poll_cb);	1910	cb => \&IO::AIO::poll_cb);
1362		1911
1363	=item IO::AIO::poll_wait	1912	=item IO::AIO::poll_wait
1364		1913
1365	If there are any outstanding requests and none of them in the result	1914	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	1915	requests are outstanding anymore.
1367	does a C<select> on the filehandle. This is useful if you want to	1916
1368	synchronously wait for some requests to finish).	1917	This is useful if you want to synchronously wait for some requests to
		1918	become ready, without actually handling them.
1369		1919
1370	See C<nreqs> for an example.	1920	See C<nreqs> for an example.
1371		1921
1372	=item IO::AIO::poll	1922	=item IO::AIO::poll
1373		1923
…		…
1460		2010
1461	Under normal circumstances you don't need to call this function.	2011	Under normal circumstances you don't need to call this function.
1462		2012
1463	=item IO::AIO::max_idle $nthreads	2013	=item IO::AIO::max_idle $nthreads
1464		2014
1465	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	2015	Limit the number of threads (default: 4) that are allowed to idle
1466	threads that did not get a request to process within 10 seconds). That	2016	(i.e., threads that did not get a request to process within the idle
1467	means if a thread becomes idle while C<$nthreads> other threads are also	2017	timeout (default: 10 seconds). That means if a thread becomes idle while
1468	idle, it will free its resources and exit.	2018	C<$nthreads> other threads are also idle, it will free its resources and
		2019	exit.
1469		2020
1470	This is useful when you allow a large number of threads (e.g. 100 or 1000)	2021	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	2022	to allow for extremely high load situations, but want to free resources
1472	under normal circumstances (1000 threads can easily consume 30MB of RAM).	2023	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1473		2024
1474	The default is probably ok in most situations, especially if thread	2025	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	2026	creation is fast. If thread creation is very slow on your system you might
1476	want to use larger values.	2027	want to use larger values.
1477		2028
		2029	=item IO::AIO::idle_timeout $seconds
		2030
		2031	Sets the minimum idle timeout (default 10) after which worker threads are
		2032	allowed to exit. SEe C<IO::AIO::max_idle>.
		2033
1478	=item IO::AIO::max_outstanding $maxreqs	2034	=item IO::AIO::max_outstanding $maxreqs
		2035
		2036	Sets the maximum number of outstanding requests to C<$nreqs>. If
		2037	you do queue up more than this number of requests, the next call to
		2038	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		2039	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2040	longer exceeded.
		2041
		2042	In other words, this setting does not enforce a queue limit, but can be
		2043	used to make poll functions block if the limit is exceeded.
1479		2044
1480	This is a very bad function to use in interactive programs because it	2045	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	2046	blocks, and a bad way to reduce concurrency because it is inexact: Better
1482	use an C<aio_group> together with a feed callback.	2047	use an C<aio_group> together with a feed callback.
1483		2048
1484	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2049	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	2050	a lot of files, you can write something 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		2051
1489	The default value is very large, so there is no practical limit on the	2052	IO::AIO::max_outstanding 32;
1490	number of outstanding requests.
1491		2053
1492	You can still queue as many requests as you want. Therefore,	2054	for my $path (...) {
1493	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2055	aio_stat $path , ...;
1494	as a stop gap to shield against fatal memory overflow (with large values).	2056	IO::AIO::poll_cb;
		2057	}
		2058
		2059	IO::AIO::flush;
		2060
		2061	The call to C<poll_cb> inside the loop will normally return instantly, but
		2062	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2063	some requests have been handled. This keeps the loop from pushing a large
		2064	number of C<aio_stat> requests onto the queue.
		2065
		2066	The default value for C<max_outstanding> is very large, so there is no
		2067	practical limit on the number of outstanding requests.
1495		2068
1496	=back	2069	=back
1497		2070
1498	=head3 STATISTICAL INFORMATION	2071	=head3 STATISTICAL INFORMATION
1499		2072
…		…
1521		2094
1522	=back	2095	=back
1523		2096
1524	=head3 MISCELLANEOUS FUNCTIONS	2097	=head3 MISCELLANEOUS FUNCTIONS
1525		2098
1526	IO::AIO implements some functions that might be useful, but are not	2099	IO::AIO implements some functions that are useful when you want to use
1527	asynchronous.	2100	some "Advanced I/O" function not available to in Perl, without going the
		2101	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2102	counterpart.
1528		2103
1529	=over 4	2104	=over 4
		2105
		2106	=item $numfd = IO::AIO::get_fdlimit
		2107
		2108	This function is I<EXPERIMENTAL> and subject to change.
		2109
		2110	Tries to find the current file descriptor limit and returns it, or
		2111	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2112	the highest valid file descriptor number.
		2113
		2114	=item IO::AIO::min_fdlimit [$numfd]
		2115
		2116	This function is I<EXPERIMENTAL> and subject to change.
		2117
		2118	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2119	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2120	is missing, it will try to set a very high limit, although this is not
		2121	recommended when you know the actual minimum that you require.
		2122
		2123	If the limit cannot be raised enough, the function makes a best-effort
		2124	attempt to increase the limit as much as possible, using various
		2125	tricks, while still failing. You can query the resulting limit using
		2126	C<IO::AIO::get_fdlimit>.
		2127
		2128	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2129	true.
1530		2130
1531	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2131	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1532		2132
1533	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2133	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1534	but is blocking (this makes most sense if you know the input data is	2134	but is blocking (this makes most sense if you know the input data is
…		…
1537		2137
1538	Returns the number of bytes copied, or C<-1> on error.	2138	Returns the number of bytes copied, or C<-1> on error.
1539		2139
1540	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2140	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1541		2141
1542	Simply calls the C<posix_fadvise> function (see it's	2142	Simply calls the C<posix_fadvise> function (see its
1543	manpage for details). The following advice constants are	2143	manpage for details). The following advice constants are
1544	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2144	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1545	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2145	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1546	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2146	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1547		2147
1548	On systems that do not implement C<posix_fadvise>, this function returns	2148	On systems that do not implement C<posix_fadvise>, this function returns
1549	ENOSYS, otherwise the return value of C<posix_fadvise>.	2149	ENOSYS, otherwise the return value of C<posix_fadvise>.
1550		2150
		2151	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2152
		2153	Simply calls the C<posix_madvise> function (see its
		2154	manpage for details). The following advice constants are
		2155	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2156	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2157	C<IO::AIO::MADV_DONTNEED>.
		2158
		2159	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2160	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2161	will be reduced to fit into the C<$scalar>.
		2162
		2163	On systems that do not implement C<posix_madvise>, this function returns
		2164	ENOSYS, otherwise the return value of C<posix_madvise>.
		2165
		2166	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2167
		2168	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2169	$scalar (see its manpage for details). The following protect
		2170	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2171	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2172
		2173	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2174	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2175	will be reduced to fit into the C<$scalar>.
		2176
		2177	On systems that do not implement C<mprotect>, this function returns
		2178	ENOSYS, otherwise the return value of C<mprotect>.
		2179
1551	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2180	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1552		2181
1553	Memory-maps a file (or anonymous memory range) and attaches it to the	2182	Memory-maps a file (or anonymous memory range) and attaches it to the
1554	given C<$scalar>, which will act like a string scalar.	2183	given C<$scalar>, which will act like a string scalar. Returns true on
		2184	success, and false otherwise.
1555		2185
		2186	The scalar must exist, but its contents do not matter - this means you
		2187	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2188	the scalar first.
		2189
1556	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2190	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1557	change the string length, and most read-only operations such as copying it	2191	which don't change the string length, and most read-only operations such
1558	or searching it with regexes and so on.	2192	as copying it or searching it with regexes and so on.
1559		2193
1560	Anything else is unsafe and will, at best, result in memory leaks.	2194	Anything else is unsafe and will, at best, result in memory leaks.
1561		2195
1562	The memory map associated with the C<$scalar> is automatically removed	2196	The memory map associated with the C<$scalar> is automatically removed
1563	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2197	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1564	C<IO::AIO::munmap> functions are called.	2198	or C<IO::AIO::munmap> functions are called on it.
1565		2199
1566	This calls the C<mmap>(2) function internally. See your system's manual	2200	This calls the C<mmap>(2) function internally. See your system's manual
1567	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2201	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1568		2202
1569	The C<$length> must be larger than zero and smaller than the actual	2203	The C<$length> must be larger than zero and smaller than the actual
1570	filesize.	2204	filesize.
1571		2205
1572	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2206	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1573	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2207	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1574		2208
1575	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2209	C<$flags> can be a combination of
1576	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2210	C<IO::AIO::MAP_SHARED> or
1577	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2211	C<IO::AIO::MAP_PRIVATE>,
		2212	or a number of system-specific flags (when not available, the are C<0>):
1578	(which is set to C<MAP_ANON> if your system only provides this	2213	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1579	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2214	C<IO::AIO::MAP_LOCKED>,
1580	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2215	C<IO::AIO::MAP_NORESERVE>,
		2216	C<IO::AIO::MAP_POPULATE>,
1581	C<IO::AIO::MAP_NONBLOCK>	2217	C<IO::AIO::MAP_NONBLOCK>,
		2218	C<IO::AIO::MAP_FIXED>,
		2219	C<IO::AIO::MAP_GROWSDOWN>,
		2220	C<IO::AIO::MAP_32BIT>,
		2221	C<IO::AIO::MAP_HUGETLB> or
		2222	C<IO::AIO::MAP_STACK>.
1582		2223
1583	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2224	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1584		2225
1585	C<$offset> is the offset from the start of the file - it generally must be	2226	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>.	2227	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1600		2241
1601	=item IO::AIO::munmap $scalar	2242	=item IO::AIO::munmap $scalar
1602		2243
1603	Removes a previous mmap and undefines the C<$scalar>.	2244	Removes a previous mmap and undefines the C<$scalar>.
1604		2245
1605	=item IO::AIO::mlockall $flags	2246	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1606		2247
1607	Calls the C<mlockall> function with the given C<$flags> (a combination of	2248	Calls the C<munlock> function, undoing the effects of a previous
1608	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL__FUTURE>).	2249	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		2250
1613	=item IO::AIO::munlockall	2251	=item IO::AIO::munlockall
1614		2252
1615	Calls the C<munlockall> function.	2253	Calls the C<munlockall> function.
1616		2254
1617	On systems that do not implement C<munlockall>, this function returns	2255	On systems that do not implement C<munlockall>, this function returns
1618	ENOSYS, otherwise the return value of C<munlockall>.	2256	ENOSYS, otherwise the return value of C<munlockall>.
		2257
		2258	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2259
		2260	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2261	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2262	should be the file offset.
		2263
		2264	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2265	silently corrupt the data in this case.
		2266
		2267	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2268	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2269	C<IO::AIO::SPLICE_F_GIFT>.
		2270
		2271	See the C<splice(2)> manpage for details.
		2272
		2273	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2274
		2275	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2276	description for C<IO::AIO::splice> above for details.
		2277
		2278	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2279
		2280	Attempts to query or change the pipe buffer size. Obviously works only
		2281	on pipes, and currently works only on GNU/Linux systems, and fails with
		2282	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2283	size on other systems, drop me a note.
		2284
		2285	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2286
		2287	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2288	C<$flags> is missing or C<0>, then this should be the same as a call to
		2289	perl's built-in C<pipe> function and create a new pipe, and works on
		2290	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2291	(..., 4096, O_BINARY)>.
		2292
		2293	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2294	the given flags (Linux 2.6.27, glibc 2.9).
		2295
		2296	On success, the read and write file handles are returned.
		2297
		2298	On error, nothing will be returned. If the pipe2 syscall is missing and
		2299	C<$flags> is non-zero, fails with C<ENOSYS>.
		2300
		2301	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2302	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2303	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1619		2304
1620	=back	2305	=back
1621		2306
1622	=cut	2307	=cut
1623		2308
…		…
1658	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2343	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1659	\&IO::AIO::poll_cb);	2344	\&IO::AIO::poll_cb);
1660		2345
1661	=head2 FORK BEHAVIOUR	2346	=head2 FORK BEHAVIOUR
1662		2347
1663	This module should do "the right thing" when the process using it forks:	2348	Usage of pthreads in a program changes the semantics of fork
		2349	considerably. Specifically, only async-safe functions can be called after
		2350	fork. Perl doesn't know about this, so in general, you cannot call fork
		2351	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2352	pthreads, so this applies, but many other extensions and (for inexplicable
		2353	reasons) perl itself often is linked against pthreads, so this limitation
		2354	applies to quite a lot of perls.
1664		2355
1665	Before the fork, IO::AIO enters a quiescent state where no requests	2356	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	2357	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	2358	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		2359
1673	In short: the parent will, after a short pause, continue as if fork had	2360	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	2361	forking. You could also try to call the L<IO::AIO::reinit> function in the
1675	yet.	2362	child:
		2363
		2364	=over 4
		2365
		2366	=item IO::AIO::reinit
		2367
		2368	Abandons all current requests and I/O threads and simply reinitialises all
		2369	data structures. This is not an operation supported by any standards, but
		2370	happens to work on GNU/Linux and some newer BSD systems.
		2371
		2372	The only reasonable use for this function is to call it after forking, if
		2373	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2374	the process will result in undefined behaviour. Calling it at any time
		2375	will also result in any undefined (by POSIX) behaviour.
		2376
		2377	=back
1676		2378
1677	=head2 MEMORY USAGE	2379	=head2 MEMORY USAGE
1678		2380
1679	Per-request usage:	2381	Per-request usage:
1680		2382

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