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Revision 1.176 by root, Sun Jan 10 23:05:11 2010 UTC vs.
Revision 1.266 by root, Tue Aug 9 11:37:53 2016 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
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my $fh = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
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;
79		82
80	# queue the request to open /etc/passwd	83	# queue the request to open /etc/passwd
81	aio_open "/etc/passwd", O_RDONLY, 0, sub {	84	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
82	my $fh = shift	85	my $fh = shift
83	or die "error while opening: $!";	86	or die "error while opening: $!";
84		87
85	# stat'ing filehandles is generally non-blocking	88	# stat'ing filehandles is generally non-blocking
86	my $size = -s $fh;	89	my $size = -s $fh;
…		…
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 = '3.5';	176	our $VERSION = 4.34;
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_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_wd);
183		189
184	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	190	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
185	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	191	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
186	min_parallel max_parallel max_idle	192	min_parallel max_parallel max_idle idle_timeout
187	nreqs nready npending nthreads	193	nreqs nready npending nthreads
188	max_poll_time max_poll_reqs	194	max_poll_time max_poll_reqs
189	sendfile fadvise);	195	sendfile fadvise madvise
		196	mmap munmap munlock munlockall);
190		197
191	push @AIO_REQ, qw(aio_busy); # not exported	198	push @AIO_REQ, qw(aio_busy); # not exported
192		199
193	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	200	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
194		201
…		…
198		205
199	=head1 FUNCTIONS	206	=head1 FUNCTIONS
200		207
201	=head2 QUICK OVERVIEW	208	=head2 QUICK OVERVIEW
202		209
203	This section simply lists the prototypes of the most important functions	210	This section simply lists the prototypes most of the functions for
204	for quick reference. See the following sections for function-by-function	211	quick reference. See the following sections for function-by-function
205	documentation.	212	documentation.
206		213
		214	aio_wd $pathname, $callback->($wd)
207	aio_open $pathname, $flags, $mode, $callback->($fh)	215	aio_open $pathname, $flags, $mode, $callback->($fh)
208	aio_close $fh, $callback->($status)	216	aio_close $fh, $callback->($status)
		217	aio_seek $fh,$offset,$whence, $callback->($offs)
209	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	218	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
210	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
211	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	220	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
212	aio_readahead $fh,$offset,$length, $callback->($retval)	221	aio_readahead $fh,$offset,$length, $callback->($retval)
213	aio_stat $fh_or_path, $callback->($status)	222	aio_stat $fh_or_path, $callback->($status)
214	aio_lstat $fh, $callback->($status)	223	aio_lstat $fh, $callback->($status)
215	aio_statvfs $fh_or_path, $callback->($statvfs)	224	aio_statvfs $fh_or_path, $callback->($statvfs)
216	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	225	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
217	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	226	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		227	aio_chmod $fh_or_path, $mode, $callback->($status)
218	aio_truncate $fh_or_path, $offset, $callback->($status)	228	aio_truncate $fh_or_path, $offset, $callback->($status)
219	aio_chmod $fh_or_path, $mode, $callback->($status)	229	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		230	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
220	aio_unlink $pathname, $callback->($status)	231	aio_unlink $pathname, $callback->($status)
221	aio_mknod $path, $mode, $dev, $callback->($status)	232	aio_mknod $pathname, $mode, $dev, $callback->($status)
222	aio_link $srcpath, $dstpath, $callback->($status)	233	aio_link $srcpath, $dstpath, $callback->($status)
223	aio_symlink $srcpath, $dstpath, $callback->($status)	234	aio_symlink $srcpath, $dstpath, $callback->($status)
224	aio_readlink $path, $callback->($link)	235	aio_readlink $pathname, $callback->($link)
		236	aio_realpath $pathname, $callback->($path)
225	aio_rename $srcpath, $dstpath, $callback->($status)	237	aio_rename $srcpath, $dstpath, $callback->($status)
226	aio_mkdir $pathname, $mode, $callback->($status)	238	aio_mkdir $pathname, $mode, $callback->($status)
227	aio_rmdir $pathname, $callback->($status)	239	aio_rmdir $pathname, $callback->($status)
228	aio_readdir $pathname, $callback->($entries)	240	aio_readdir $pathname, $callback->($entries)
229	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	241	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
230	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	242	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
231	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	243	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		244	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
232	aio_load $path, $data, $callback->($status)	245	aio_load $pathname, $data, $callback->($status)
233	aio_copy $srcpath, $dstpath, $callback->($status)	246	aio_copy $srcpath, $dstpath, $callback->($status)
234	aio_move $srcpath, $dstpath, $callback->($status)	247	aio_move $srcpath, $dstpath, $callback->($status)
235	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
236	aio_rmtree $path, $callback->($status)	248	aio_rmtree $pathname, $callback->($status)
		249	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		250	aio_ioctl $fh, $request, $buf, $callback->($status)
237	aio_sync $callback->($status)	251	aio_sync $callback->($status)
		252	aio_syncfs $fh, $callback->($status)
238	aio_fsync $fh, $callback->($status)	253	aio_fsync $fh, $callback->($status)
239	aio_fdatasync $fh, $callback->($status)	254	aio_fdatasync $fh, $callback->($status)
240	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	255	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
241	aio_pathsync $path, $callback->($status)	256	aio_pathsync $pathname, $callback->($status)
242	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	257	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
243	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	258	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		259	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		260	aio_mlockall $flags, $callback->($status)
244	aio_group $callback->(...)	261	aio_group $callback->(...)
245	aio_nop $callback->()	262	aio_nop $callback->()
246		263
247	$prev_pri = aioreq_pri [$pri]	264	$prev_pri = aioreq_pri [$pri]
248	aioreq_nice $pri_adjust	265	aioreq_nice $pri_adjust
…		…
254	IO::AIO::max_poll_reqs $nreqs	271	IO::AIO::max_poll_reqs $nreqs
255	IO::AIO::max_poll_time $seconds	272	IO::AIO::max_poll_time $seconds
256	IO::AIO::min_parallel $nthreads	273	IO::AIO::min_parallel $nthreads
257	IO::AIO::max_parallel $nthreads	274	IO::AIO::max_parallel $nthreads
258	IO::AIO::max_idle $nthreads	275	IO::AIO::max_idle $nthreads
		276	IO::AIO::idle_timeout $seconds
259	IO::AIO::max_outstanding $maxreqs	277	IO::AIO::max_outstanding $maxreqs
260	IO::AIO::nreqs	278	IO::AIO::nreqs
261	IO::AIO::nready	279	IO::AIO::nready
262	IO::AIO::npending	280	IO::AIO::npending
263		281
264	IO::AIO::sendfile $ofh, $ifh, $offset, $count	282	IO::AIO::sendfile $ofh, $ifh, $offset, $count
265	IO::AIO::fadvise $fh, $offset, $len, $advice	283	IO::AIO::fadvise $fh, $offset, $len, $advice
266	IO::AIO::mlockall $flags	284	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		285	IO::AIO::munmap $scalar
		286	IO::AIO::madvise $scalar, $offset, $length, $advice
		287	IO::AIO::mprotect $scalar, $offset, $length, $protect
		288	IO::AIO::munlock $scalar, $offset = 0, $length = undef
267	IO::AIO::munlockall	289	IO::AIO::munlockall
268		290
269	=head2 AIO REQUEST FUNCTIONS	291	=head2 API NOTES
270		292
271	All the C<aio_*> calls are more or less thin wrappers around the syscall	293	All the C<aio_*> calls are more or less thin wrappers around the syscall
272	with the same name (sans C<aio_>). The arguments are similar or identical,	294	with the same name (sans C<aio_>). The arguments are similar or identical,
273	and they all accept an additional (and optional) C<$callback> argument	295	and they all accept an additional (and optional) C<$callback> argument
274	which must be a code reference. This code reference will get called with	296	which must be a code reference. This code reference will be called after
275	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	297	the syscall has been executed in an asynchronous fashion. The results
276	perl, which usually delivers "false") as its sole argument after the given	298	of the request will be passed as arguments to the callback (and, if an
277	syscall has been executed asynchronously.	299	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		300	most syscalls return C<-1> on error, unlike perl, which usually delivers
		301	"false").
		302
		303	Some requests (such as C<aio_readdir>) pass the actual results and
		304	communicate failures by passing C<undef>.
278		305
279	All functions expecting a filehandle keep a copy of the filehandle	306	All functions expecting a filehandle keep a copy of the filehandle
280	internally until the request has finished.	307	internally until the request has finished.
281		308
282	All functions return request objects of type L<IO::AIO::REQ> that allow	309	All functions return request objects of type L<IO::AIO::REQ> that allow
283	further manipulation of those requests while they are in-flight.	310	further manipulation of those requests while they are in-flight.
284		311
285	The pathnames you pass to these routines I<must> be absolute and	312	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	313	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	314	current working directory could have changed. Alternatively, you can
288	changed. Alternatively, you can make sure that you never change the	315	make sure that you never change the current working directory anywhere
289	current working directory anywhere in the program and then use relative	316	in the program and then use relative paths. You can also take advantage
290	paths.	317	of IO::AIOs working directory abstraction, that lets you specify paths
		318	relative to some previously-opened "working directory object" - see the
		319	description of the C<IO::AIO::WD> class later in this document.
291		320
292	To encode pathnames as octets, either make sure you either: a) always pass	321	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	322	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	323	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	324	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)	325	effect in the user environment, d) use Glib::filename_from_unicode on
297	use something else to ensure your scalar has the correct contents.	326	unicode filenames or e) use something else to ensure your scalar has the
		327	correct contents.
298		328
299	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	329	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
300	handles correctly whether it is set or not.	330	handles correctly whether it is set or not.
		331
		332	=head2 AIO REQUEST FUNCTIONS
301		333
302	=over 4	334	=over 4
303		335
304	=item $prev_pri = aioreq_pri [$pri]	336	=item $prev_pri = aioreq_pri [$pri]
305		337
…		…
335		367
336		368
337	=item aio_open $pathname, $flags, $mode, $callback->($fh)	369	=item aio_open $pathname, $flags, $mode, $callback->($fh)
338		370
339	Asynchronously open or create a file and call the callback with a newly	371	Asynchronously open or create a file and call the callback with a newly
340	created filehandle for the file.	372	created filehandle for the file (or C<undef> in case of an error).
341		373
342	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	374	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
343	for an explanation.	375	for an explanation.
344		376
345	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	377	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
352	by the umask in effect then the request is being executed, so better never	384	by the umask in effect then the request is being executed, so better never
353	change the umask.	385	change the umask.
354		386
355	Example:	387	Example:
356		388
357	aio_open "/etc/passwd", O_RDONLY, 0, sub {	389	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
358	if ($_[0]) {	390	if ($_[0]) {
359	print "open successful, fh is $_[0]\n";	391	print "open successful, fh is $_[0]\n";
360	...	392	...
361	} else {	393	} else {
362	die "open failed: $!\n";	394	die "open failed: $!\n";
363	}	395	}
364	};	396	};
365		397
		398	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		399	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		400	following POSIX and non-POSIX constants are available (missing ones on
		401	your system are, as usual, C<0>):
		402
		403	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		404	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		405	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		406
366		407
367	=item aio_close $fh, $callback->($status)	408	=item aio_close $fh, $callback->($status)
368		409
369	Asynchronously close a file and call the callback with the result	410	Asynchronously close a file and call the callback with the result
370	code.	411	code.
…		…
379	Or in other words: the file descriptor will be closed, but it will not be	420	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.	421	free for reuse until the perl filehandle is closed.
381		422
382	=cut	423	=cut
383		424
		425	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		426
		427	Seeks the filehandle to the new C<$offset>, similarly to perl's
		428	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		429	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		430	C<IO::AIO::SEEK_END>).
		431
		432	The resulting absolute offset will be passed to the callback, or C<-1> in
		433	case of an error.
		434
		435	In theory, the C<$whence> constants could be different than the
		436	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		437	so don't panic.
		438
		439	As a GNU/Linux (and maybe Solaris) extension, also the constants
		440	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		441	could be found. No guarantees about suitability for use in C<aio_seek> or
		442	Perl's C<sysseek> can be made though, although I would naively assume they
		443	"just work".
		444
384	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	445	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
385		446
386	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	447	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
387		448
388	Reads or writes C<$length> bytes from or to the specified C<$fh> and	449	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<$dataoffset>	450	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
390	and calls the callback without the actual number of bytes read (or -1 on	451	and calls the callback with the actual number of bytes read (or -1 on
391	error, just like the syscall).	452	error, just like the syscall).
392		453
393	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	454	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
394	offset plus the actual number of bytes read.	455	offset plus the actual number of bytes read.
395		456
…		…
420		481
421	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	482	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
422	reading at byte offset C<$in_offset>, and starts writing at the current	483	reading at byte offset C<$in_offset>, and starts writing at the current
423	file offset of C<$out_fh>. Because of that, it is not safe to issue more	484	file offset of C<$out_fh>. Because of that, it is not safe to issue more
424	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	485	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
425	other.	486	other. The same C<$in_fh> works fine though, as this function does not
		487	move or use the file offset of C<$in_fh>.
426		488
		489	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		490	are written, and there is no way to find out how many more bytes have been
		491	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		492	number of bytes written to C<$out_fh>. Only if the result value equals
		493	C<$length> one can assume that C<$length> bytes have been read.
		494
		495	Unlike with other C<aio_> functions, it makes a lot of sense to use
		496	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		497	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		498	the socket I/O will be non-blocking. Note, however, that you can run
		499	into a trap where C<aio_sendfile> reads some data with readahead, then
		500	fails to write all data, and when the socket is ready the next time, the
		501	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		502	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		503	resource usage.
		504
427	This call tries to make use of a native C<sendfile> syscall to provide	505	This call tries to make use of a native C<sendfile>-like syscall to
428	zero-copy operation. For this to work, C<$out_fh> should refer to a	506	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.	507	a socket, and C<$in_fh> should refer to an mmap'able file.
430		508
431	If a native sendfile cannot be found or it fails with C<ENOSYS>,	509	If a native sendfile cannot be found or it fails with C<ENOSYS>,
432	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	510	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
433	it will be emulated, so you can call C<aio_sendfile> on any type of	511	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
434	filehandle regardless of the limitations of the operating system.	512	type of filehandle regardless of the limitations of the operating system.
435		513
436	Please note, however, that C<aio_sendfile> can read more bytes from	514	As native sendfile syscalls (as practically any non-POSIX interface hacked
437	C<$in_fh> than are written, and there is no way to find out how many	515	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	516	on many systems, this implementation tries to work around some known bugs
439	provides the number of bytes written to C<$out_fh>. Only if the result	517	in Linux and FreeBSD kernels (probably others, too), but that might fail,
440	value equals C<$length> one can assume that C<$length> bytes have been	518	so you really really should check the return value of C<aio_sendfile> -
441	read.	519	fewer bytes than expected might have been transferred.
442		520
443		521
444	=item aio_readahead $fh,$offset,$length, $callback->($retval)	522	=item aio_readahead $fh,$offset,$length, $callback->($retval)
445		523
446	C<aio_readahead> populates the page cache with data from a file so that	524	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	528	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	529	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	530	(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.	531	file. The current file offset of the file is left unchanged.
454		532
455	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	533	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.	534	be emulated by simply reading the data, which would have a similar effect.
457		535
458		536
459	=item aio_stat $fh_or_path, $callback->($status)	537	=item aio_stat $fh_or_path, $callback->($status)
460		538
461	=item aio_lstat $fh, $callback->($status)	539	=item aio_lstat $fh, $callback->($status)
…		…
468	for an explanation.	546	for an explanation.
469		547
470	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	548	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	549	error when stat'ing a large file, the results will be silently truncated
472	unless perl itself is compiled with large file support.	550	unless perl itself is compiled with large file support.
		551
		552	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		553	following constants and functions (if not implemented, the constants will
		554	be C<0> and the functions will either C<croak> or fall back on traditional
		555	behaviour).
		556
		557	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		558	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		559	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
473		560
474	Example: Print the length of F</etc/passwd>:	561	Example: Print the length of F</etc/passwd>:
475		562
476	aio_stat "/etc/passwd", sub {	563	aio_stat "/etc/passwd", sub {
477	$_[0] and die "stat failed: $!";	564	$_[0] and die "stat failed: $!";
…		…
521	namemax => 255,	608	namemax => 255,
522	frsize => 1024,	609	frsize => 1024,
523	fsid => 1810	610	fsid => 1810
524	}	611	}
525		612
		613	Here is a (likely partial - send me updates!) list of fsid values used by
		614	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		615
		616	0x0000adf5 adfs
		617	0x0000adff affs
		618	0x5346414f afs
		619	0x09041934 anon-inode filesystem
		620	0x00000187 autofs
		621	0x42465331 befs
		622	0x1badface bfs
		623	0x42494e4d binfmt_misc
		624	0x9123683e btrfs
		625	0x0027e0eb cgroupfs
		626	0xff534d42 cifs
		627	0x73757245 coda
		628	0x012ff7b7 coh
		629	0x28cd3d45 cramfs
		630	0x453dcd28 cramfs-wend (wrong endianness)
		631	0x64626720 debugfs
		632	0x00001373 devfs
		633	0x00001cd1 devpts
		634	0x0000f15f ecryptfs
		635	0x00414a53 efs
		636	0x0000137d ext
		637	0x0000ef53 ext2/ext3/ext4
		638	0x0000ef51 ext2
		639	0xf2f52010 f2fs
		640	0x00004006 fat
		641	0x65735546 fuseblk
		642	0x65735543 fusectl
		643	0x0bad1dea futexfs
		644	0x01161970 gfs2
		645	0x47504653 gpfs
		646	0x00004244 hfs
		647	0xf995e849 hpfs
		648	0x00c0ffee hostfs
		649	0x958458f6 hugetlbfs
		650	0x2bad1dea inotifyfs
		651	0x00009660 isofs
		652	0x000072b6 jffs2
		653	0x3153464a jfs
		654	0x6b414653 k-afs
		655	0x0bd00bd0 lustre
		656	0x0000137f minix
		657	0x0000138f minix 30 char names
		658	0x00002468 minix v2
		659	0x00002478 minix v2 30 char names
		660	0x00004d5a minix v3
		661	0x19800202 mqueue
		662	0x00004d44 msdos
		663	0x0000564c novell
		664	0x00006969 nfs
		665	0x6e667364 nfsd
		666	0x00003434 nilfs
		667	0x5346544e ntfs
		668	0x00009fa1 openprom
		669	0x7461636F ocfs2
		670	0x00009fa0 proc
		671	0x6165676c pstorefs
		672	0x0000002f qnx4
		673	0x68191122 qnx6
		674	0x858458f6 ramfs
		675	0x52654973 reiserfs
		676	0x00007275 romfs
		677	0x67596969 rpc_pipefs
		678	0x73636673 securityfs
		679	0xf97cff8c selinux
		680	0x0000517b smb
		681	0x534f434b sockfs
		682	0x73717368 squashfs
		683	0x62656572 sysfs
		684	0x012ff7b6 sysv2
		685	0x012ff7b5 sysv4
		686	0x01021994 tmpfs
		687	0x15013346 udf
		688	0x00011954 ufs
		689	0x54190100 ufs byteswapped
		690	0x00009fa2 usbdevfs
		691	0x01021997 v9fs
		692	0xa501fcf5 vxfs
		693	0xabba1974 xenfs
		694	0x012ff7b4 xenix
		695	0x58465342 xfs
		696	0x012fd16d xia
526		697
527	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	698	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
528		699
529	Works like perl's C<utime> function (including the special case of $atime	700	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	701	and $mtime being undef). Fractional times are supported if the underlying
…		…
558	=item aio_truncate $fh_or_path, $offset, $callback->($status)	729	=item aio_truncate $fh_or_path, $offset, $callback->($status)
559		730
560	Works like truncate(2) or ftruncate(2).	731	Works like truncate(2) or ftruncate(2).
561		732
562		733
		734	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		735
		736	Allocates or frees disk space according to the C<$mode> argument. See the
		737	linux C<fallocate> documentation for details.
		738
		739	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		740	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		741	to deallocate a file range.
		742
		743	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		744	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		745	your L<fallocate(2)> manpage).
		746
		747	The file system block size used by C<fallocate> is presumably the
		748	C<f_bsize> returned by C<statvfs>.
		749
		750	If C<fallocate> isn't available or cannot be emulated (currently no
		751	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		752
		753
563	=item aio_chmod $fh_or_path, $mode, $callback->($status)	754	=item aio_chmod $fh_or_path, $mode, $callback->($status)
564		755
565	Works like perl's C<chmod> function.	756	Works like perl's C<chmod> function.
566		757
567		758
…		…
569		760
570	Asynchronously unlink (delete) a file and call the callback with the	761	Asynchronously unlink (delete) a file and call the callback with the
571	result code.	762	result code.
572		763
573		764
574	=item aio_mknod $path, $mode, $dev, $callback->($status)	765	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
575		766
576	[EXPERIMENTAL]	767	[EXPERIMENTAL]
577		768
578	Asynchronously create a device node (or fifo). See mknod(2).	769	Asynchronously create a device node (or fifo). See mknod(2).
579		770
580	The only (POSIX-) portable way of calling this function is:	771	The only (POSIX-) portable way of calling this function is:
581		772
582	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	773	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
583		774
		775	See C<aio_stat> for info about some potentially helpful extra constants
		776	and functions.
584		777
585	=item aio_link $srcpath, $dstpath, $callback->($status)	778	=item aio_link $srcpath, $dstpath, $callback->($status)
586		779
587	Asynchronously create a new link to the existing object at C<$srcpath> at	780	Asynchronously create a new link to the existing object at C<$srcpath> at
588	the path C<$dstpath> and call the callback with the result code.	781	the path C<$dstpath> and call the callback with the result code.
…		…
592		785
593	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	786	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
594	the path C<$dstpath> and call the callback with the result code.	787	the path C<$dstpath> and call the callback with the result code.
595		788
596		789
597	=item aio_readlink $path, $callback->($link)	790	=item aio_readlink $pathname, $callback->($link)
598		791
599	Asynchronously read the symlink specified by C<$path> and pass it to	792	Asynchronously read the symlink specified by C<$path> and pass it to
600	the callback. If an error occurs, nothing or undef gets passed to the	793	the callback. If an error occurs, nothing or undef gets passed to the
601	callback.	794	callback.
602		795
603		796
		797	=item aio_realpath $pathname, $callback->($path)
		798
		799	Asynchronously make the path absolute and resolve any symlinks in
		800	C<$path>. The resulting path only consists of directories (same as
		801	L<Cwd::realpath>).
		802
		803	This request can be used to get the absolute path of the current working
		804	directory by passing it a path of F<.> (a single dot).
		805
		806
604	=item aio_rename $srcpath, $dstpath, $callback->($status)	807	=item aio_rename $srcpath, $dstpath, $callback->($status)
605		808
606	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	809	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
607	rename(2) and call the callback with the result code.	810	rename(2) and call the callback with the result code.
		811
		812	On systems that support the AIO::WD working directory abstraction
		813	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		814	of failing, C<rename> is called on the absolute path of C<$wd>.
608		815
609		816
610	=item aio_mkdir $pathname, $mode, $callback->($status)	817	=item aio_mkdir $pathname, $mode, $callback->($status)
611		818
612	Asynchronously mkdir (create) a directory and call the callback with	819	Asynchronously mkdir (create) a directory and call the callback with
…		…
617	=item aio_rmdir $pathname, $callback->($status)	824	=item aio_rmdir $pathname, $callback->($status)
618		825
619	Asynchronously rmdir (delete) a directory and call the callback with the	826	Asynchronously rmdir (delete) a directory and call the callback with the
620	result code.	827	result code.
621		828
		829	On systems that support the AIO::WD working directory abstraction
		830	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		831	C<rmdir> is called on the absolute path of C<$wd>.
		832
622		833
623	=item aio_readdir $pathname, $callback->($entries)	834	=item aio_readdir $pathname, $callback->($entries)
624		835
625	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	836	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	837	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
630	array-ref with the filenames.	841	array-ref with the filenames.
631		842
632		843
633	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	844	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
634		845
635	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	846	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	847	tune behaviour and output format. In case of an error, C<$entries> will be
637	C<undef>.	848	C<undef>.
638		849
639	The flags are a combination of the following constants, ORed together (the	850	The flags are a combination of the following constants, ORed together (the
640	flags will also be passed to the callback, possibly modified):	851	flags will also be passed to the callback, possibly modified):
641		852
642	=over 4	853	=over 4
643		854
644	=item IO::AIO::READDIR_DENTS	855	=item IO::AIO::READDIR_DENTS
645		856
646	When this flag is off, then the callback gets an arrayref with of names	857	When this flag is off, then the callback gets an arrayref consisting of
647	only (as with C<aio_readdir>), otherwise it gets an arrayref with	858	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
648	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	859	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
649	entry in more detail.	860	entry in more detail.
650		861
651	C<$name> is the name of the entry.	862	C<$name> is the name of the entry.
652		863
…		…
665	systems that do not deliver the inode information.	876	systems that do not deliver the inode information.
666		877
667	=item IO::AIO::READDIR_DIRS_FIRST	878	=item IO::AIO::READDIR_DIRS_FIRST
668		879
669	When this flag is set, then the names will be returned in an order where	880	When this flag is set, then the names will be returned in an order where
670	likely directories come first. This is useful when you need to quickly	881	likely directories come first, in optimal stat order. This is useful when
671	find directories, or you want to find all directories while avoiding to	882	you need to quickly find directories, or you want to find all directories
672	stat() each entry.	883	while avoiding to stat() each entry.
673		884
674	If the system returns type information in readdir, then this is used	885	If the system returns type information in readdir, then this is used
675	to find directories directly. Otherwise, likely directories are files	886	to find directories directly. Otherwise, likely directories are names
676	beginning with ".", or otherwise files with no dots, of which files with	887	beginning with ".", or otherwise names with no dots, of which names with
677	short names are tried first.	888	short names are tried first.
678		889
679	=item IO::AIO::READDIR_STAT_ORDER	890	=item IO::AIO::READDIR_STAT_ORDER
680		891
681	When this flag is set, then the names will be returned in an order	892	When this flag is set, then the names will be returned in an order
…		…
688		899
689	=item IO::AIO::READDIR_FOUND_UNKNOWN	900	=item IO::AIO::READDIR_FOUND_UNKNOWN
690		901
691	This flag should not be set when calling C<aio_readdirx>. Instead, it	902	This flag should not be set when calling C<aio_readdirx>. Instead, it
692	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	903	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
693	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	904	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
694	C<$type>'s are known, which can be used to speed up some algorithms.	905	C<$type>'s are known, which can be used to speed up some algorithms.
695		906
696	=back	907	=back
697		908
698		909
699	=item aio_load $path, $data, $callback->($status)	910	=item aio_load $pathname, $data, $callback->($status)
700		911
701	This is a composite request that tries to fully load the given file into	912	This is a composite request that tries to fully load the given file into
702	memory. Status is the same as with aio_read.	913	memory. Status is the same as with aio_read.
703		914
704	=cut	915	=cut
…		…
826	if ($_[0] && $! == EXDEV) {	1037	if ($_[0] && $! == EXDEV) {
827	aioreq_pri $pri;	1038	aioreq_pri $pri;
828	add $grp aio_copy $src, $dst, sub {	1039	add $grp aio_copy $src, $dst, sub {
829	$grp->result ($_[0]);	1040	$grp->result ($_[0]);
830		1041
831	if (!$_[0]) {	1042	unless ($_[0]) {
832	aioreq_pri $pri;	1043	aioreq_pri $pri;
833	add $grp aio_unlink $src;	1044	add $grp aio_unlink $src;
834	}	1045	}
835	};	1046	};
836	} else {	1047	} else {
…		…
839	};	1050	};
840		1051
841	$grp	1052	$grp
842	}	1053	}
843		1054
844	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1055	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
845		1056
846	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1057	Scans a directory (similar to C<aio_readdir>) but additionally tries to
847	efficiently separate the entries of directory C<$path> into two sets of	1058	efficiently separate the entries of directory C<$path> into two sets of
848	names, directories you can recurse into (directories), and ones you cannot	1059	names, directories you can recurse into (directories), and ones you cannot
849	recurse into (everything else, including symlinks to directories).	1060	recurse into (everything else, including symlinks to directories).
…		…
880	Then entries will be sorted into likely directories a non-initial dot	1091	Then entries will be sorted into likely directories a non-initial dot
881	currently) and likely non-directories (see C<aio_readdirx>). Then every	1092	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,	1093	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	1094	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	1095	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	1096	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	1097	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	1098	data (e.g. ext2fs filetype feature), even on systems that cannot return
888	the filetype information on readdir.	1099	the filetype information on readdir.
889		1100
890	If the known number of directories (link count - 2) has been reached, the	1101	If the known number of directories (link count - 2) has been reached, the
…		…
906		1117
907	my $grp = aio_group $cb;	1118	my $grp = aio_group $cb;
908		1119
909	$maxreq = 4 if $maxreq <= 0;	1120	$maxreq = 4 if $maxreq <= 0;
910		1121
911	# stat once	1122	# get a wd object
912	aioreq_pri $pri;	1123	aioreq_pri $pri;
913	add $grp aio_stat $path, sub {	1124	add $grp aio_wd $path, sub {
		1125	$_[0]
914	return $grp->result () if $_[0];	1126	or return $grp->result ();
915	my $now = time;
916	my $hash1 = join ":", (stat _)[0,1,3,7,9];
917		1127
918	# read the directory entries	1128	my $wd = [shift, "."];
		1129
		1130	# stat once
919	aioreq_pri $pri;	1131	aioreq_pri $pri;
920	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1132	add $grp aio_stat $wd, sub {
921	my $entries = shift
922	or return $grp->result ();	1133	return $grp->result () if $_[0];
		1134	my $now = time;
		1135	my $hash1 = join ":", (stat _)[0,1,3,7,9];
923		1136
924	# stat the dir another time	1137	# read the directory entries
925	aioreq_pri $pri;	1138	aioreq_pri $pri;
		1139	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1140	my $entries = shift
		1141	or return $grp->result ();
		1142
		1143	# stat the dir another time
		1144	aioreq_pri $pri;
926	add $grp aio_stat $path, sub {	1145	add $grp aio_stat $wd, sub {
927	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1146	my $hash2 = join ":", (stat _)[0,1,3,7,9];
928		1147
929	my $ndirs;	1148	my $ndirs;
930		1149
931	# take the slow route if anything looks fishy	1150	# take the slow route if anything looks fishy
932	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1151	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
933	$ndirs = -1;	1152	$ndirs = -1;
934	} else {	1153	} else {
935	# if nlink == 2, we are finished	1154	# if nlink == 2, we are finished
936	# for non-posix-fs's, we rely on nlink < 2	1155	# for non-posix-fs's, we rely on nlink < 2
937	$ndirs = (stat _)[3] - 2	1156	$ndirs = (stat _)[3] - 2
938	or return $grp->result ([], $entries);	1157	or return $grp->result ([], $entries);
939	}	1158	}
940		1159
941	my (@dirs, @nondirs);	1160	my (@dirs, @nondirs);
942		1161
943	my $statgrp = add $grp aio_group sub {	1162	my $statgrp = add $grp aio_group sub {
944	$grp->result (\@dirs, \@nondirs);	1163	$grp->result (\@dirs, \@nondirs);
945	};	1164	};
946		1165
947	limit $statgrp $maxreq;	1166	limit $statgrp $maxreq;
948	feed $statgrp sub {	1167	feed $statgrp sub {
949	return unless @$entries;	1168	return unless @$entries;
950	my $entry = shift @$entries;	1169	my $entry = shift @$entries;
951		1170
952	aioreq_pri $pri;	1171	aioreq_pri $pri;
		1172	$wd->[1] = "$entry/.";
953	add $statgrp aio_stat "$path/$entry/.", sub {	1173	add $statgrp aio_stat $wd, sub {
954	if ($_[0] < 0) {	1174	if ($_[0] < 0) {
955	push @nondirs, $entry;	1175	push @nondirs, $entry;
956	} else {	1176	} else {
957	# need to check for real directory	1177	# need to check for real directory
958	aioreq_pri $pri;	1178	aioreq_pri $pri;
		1179	$wd->[1] = $entry;
959	add $statgrp aio_lstat "$path/$entry", sub {	1180	add $statgrp aio_lstat $wd, sub {
960	if (-d _) {	1181	if (-d _) {
961	push @dirs, $entry;	1182	push @dirs, $entry;
962		1183
963	unless (--$ndirs) {	1184	unless (--$ndirs) {
964	push @nondirs, @$entries;	1185	push @nondirs, @$entries;
965	feed $statgrp;	1186	feed $statgrp;
		1187	}
		1188	} else {
		1189	push @nondirs, $entry;
966	}	1190	}
967	} else {
968	push @nondirs, $entry;
969	}	1191	}
970	}	1192	}
971	}	1193	};
972	};	1194	};
973	};	1195	};
974	};	1196	};
975	};	1197	};
976	};	1198	};
977		1199
978	$grp	1200	$grp
979	}	1201	}
980		1202
981	=item aio_rmtree $path, $callback->($status)	1203	=item aio_rmtree $pathname, $callback->($status)
982		1204
983	Delete a directory tree starting (and including) C<$path>, return the	1205	Delete a directory tree starting (and including) C<$path>, return the
984	status of the final C<rmdir> only. This is a composite request that	1206	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	1207	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
986	everything else.	1208	everything else.
987		1209
988	=cut	1210	=cut
989		1211
…		…
1011	};	1233	};
1012		1234
1013	$grp	1235	$grp
1014	}	1236	}
1015		1237
		1238	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1239
		1240	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1241
		1242	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1243	they execute asynchronously and pass the return value to the callback.
		1244
		1245	Both calls can be used for a lot of things, some of which make more sense
		1246	to run asynchronously in their own thread, while some others make less
		1247	sense. For example, calls that block waiting for external events, such
		1248	as locking, will also lock down an I/O thread while it is waiting, which
		1249	can deadlock the whole I/O system. At the same time, there might be no
		1250	alternative to using a thread to wait.
		1251
		1252	So in general, you should only use these calls for things that do
		1253	(filesystem) I/O, not for things that wait for other events (network,
		1254	other processes), although if you are careful and know what you are doing,
		1255	you still can.
		1256
		1257	The following constants are available (missing ones are, as usual C<0>):
		1258
		1259	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1260
		1261	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1262	C<FS_IOC_FIEMAP>.
		1263
		1264	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1265	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1266
		1267	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1268	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1269	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1270	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1271	C<FS_FL_USER_MODIFIABLE>.
		1272
		1273	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1274	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1275	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1276	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1277
1016	=item aio_sync $callback->($status)	1278	=item aio_sync $callback->($status)
1017		1279
1018	Asynchronously call sync and call the callback when finished.	1280	Asynchronously call sync and call the callback when finished.
1019		1281
1020	=item aio_fsync $fh, $callback->($status)	1282	=item aio_fsync $fh, $callback->($status)
…		…
1027	Asynchronously call fdatasync on the given filehandle and call the	1289	Asynchronously call fdatasync on the given filehandle and call the
1028	callback with the fdatasync result code.	1290	callback with the fdatasync result code.
1029		1291
1030	If this call isn't available because your OS lacks it or it couldn't be	1292	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.	1293	detected, it will be emulated by calling C<fsync> instead.
		1294
		1295	=item aio_syncfs $fh, $callback->($status)
		1296
		1297	Asynchronously call the syncfs syscall to sync the filesystem associated
		1298	to the given filehandle and call the callback with the syncfs result
		1299	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1300	errno to C<ENOSYS> nevertheless.
1032		1301
1033	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1302	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1034		1303
1035	Sync the data portion of the file specified by C<$offset> and C<$length>	1304	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	1305	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1040	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1309	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1041	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1310	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1042	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1311	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1043	manpage for details.	1312	manpage for details.
1044		1313
1045	=item aio_pathsync $path, $callback->($status)	1314	=item aio_pathsync $pathname, $callback->($status)
1046		1315
1047	This request tries to open, fsync and close the given path. This is a	1316	This request tries to open, fsync and close the given path. This is a
1048	composite request intended to sync directories after directory operations	1317	composite request intended to sync directories after directory operations
1049	(E.g. rename). This might not work on all operating systems or have any	1318	(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	1319	specific effect, but usually it makes sure that directory changes get
…		…
1102		1371
1103	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1372	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1104	scalars.	1373	scalars.
1105		1374
1106	It touches (reads or writes) all memory pages in the specified	1375	It touches (reads or writes) all memory pages in the specified
1107	range inside the scalar. All caveats and parameters are the same	1376	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	1377	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	1378	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	1379	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1111	writing an octet from it, which dirties the page).	1380	writing an octet from it, which dirties the page).
		1381
		1382	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1383
		1384	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1385	scalars.
		1386
		1387	It reads in all the pages of the underlying storage into memory (if any)
		1388	and locks them, so they are not getting swapped/paged out or removed.
		1389
		1390	If C<$length> is undefined, then the scalar will be locked till the end.
		1391
		1392	On systems that do not implement C<mlock>, this function returns C<-1>
		1393	and sets errno to C<ENOSYS>.
		1394
		1395	Note that the corresponding C<munlock> is synchronous and is
		1396	documented under L<MISCELLANEOUS FUNCTIONS>.
		1397
		1398	Example: open a file, mmap and mlock it - both will be undone when
		1399	C<$data> gets destroyed.
		1400
		1401	open my $fh, "<", $path or die "$path: $!";
		1402	my $data;
		1403	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1404	aio_mlock $data; # mlock in background
		1405
		1406	=item aio_mlockall $flags, $callback->($status)
		1407
		1408	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1409	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1410
		1411	On systems that do not implement C<mlockall>, this function returns C<-1>
		1412	and sets errno to C<ENOSYS>.
		1413
		1414	Note that the corresponding C<munlockall> is synchronous and is
		1415	documented under L<MISCELLANEOUS FUNCTIONS>.
		1416
		1417	Example: asynchronously lock all current and future pages into memory.
		1418
		1419	aio_mlockall IO::AIO::MCL_FUTURE;
		1420
		1421	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1422
		1423	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1424	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1425	the ioctl is not available on your OS, then this request will fail with
		1426	C<ENOSYS>.
		1427
		1428	C<$start> is the starting offset to query extents for, C<$length> is the
		1429	size of the range to query - if it is C<undef>, then the whole file will
		1430	be queried.
		1431
		1432	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1433	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1434	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1435	the data portion.
		1436
		1437	C<$count> is the maximum number of extent records to return. If it is
		1438	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1439	case, if it is C<0>, then the callback receives the number of extents
		1440	instead of the extents themselves (which is unreliable, see below).
		1441
		1442	If an error occurs, the callback receives no arguments. The special
		1443	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1444
		1445	Otherwise, the callback receives an array reference with extent
		1446	structures. Each extent structure is an array reference itself, with the
		1447	following members:
		1448
		1449	[$logical, $physical, $length, $flags]
		1450
		1451	Flags is any combination of the following flag values (typically either C<0>
		1452	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1453
		1454	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1455	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1456	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1457	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1458	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1459	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1460
		1461	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1462	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1463	it to return all extents of a range for files with large number of
		1464	extents. The code works around all these issues if C<$count> is undef.
1112		1465
1113	=item aio_group $callback->(...)	1466	=item aio_group $callback->(...)
1114		1467
1115	This is a very special aio request: Instead of doing something, it is a	1468	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	1469	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	1506	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	1507	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.	1508	except to put your application under artificial I/O pressure.
1156		1509
1157	=back	1510	=back
		1511
		1512
		1513	=head2 IO::AIO::WD - multiple working directories
		1514
		1515	Your process only has one current working directory, which is used by all
		1516	threads. This makes it hard to use relative paths (some other component
		1517	could call C<chdir> at any time, and it is hard to control when the path
		1518	will be used by IO::AIO).
		1519
		1520	One solution for this is to always use absolute paths. This usually works,
		1521	but can be quite slow (the kernel has to walk the whole path on every
		1522	access), and can also be a hassle to implement.
		1523
		1524	Newer POSIX systems have a number of functions (openat, fdopendir,
		1525	futimensat and so on) that make it possible to specify working directories
		1526	per operation.
		1527
		1528	For portability, and because the clowns who "designed", or shall I write,
		1529	perpetrated this new interface were obviously half-drunk, this abstraction
		1530	cannot be perfect, though.
		1531
		1532	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1533	object. This object stores the canonicalised, absolute version of the
		1534	path, and on systems that allow it, also a directory file descriptor.
		1535
		1536	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1537	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1538	object and a pathname instead (or the IO::AIO::WD object alone, which
		1539	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1540	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1541	to that IO::AIO::WD object.
		1542
		1543	For example, to get a wd object for F</etc> and then stat F<passwd>
		1544	inside, you would write:
		1545
		1546	aio_wd "/etc", sub {
		1547	my $etcdir = shift;
		1548
		1549	# although $etcdir can be undef on error, there is generally no reason
		1550	# to check for errors here, as aio_stat will fail with ENOENT
		1551	# when $etcdir is undef.
		1552
		1553	aio_stat [$etcdir, "passwd"], sub {
		1554	# yay
		1555	};
		1556	};
		1557
		1558	The fact that C<aio_wd> is a request and not a normal function shows that
		1559	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1560	which is why it is done asynchronously.
		1561
		1562	To stat the directory obtained with C<aio_wd> above, one could write
		1563	either of the following three request calls:
		1564
		1565	aio_lstat "/etc" , sub { ... # pathname as normal string
		1566	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1567	aio_lstat $wd , sub { ... # shorthand for the previous
		1568
		1569	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1570	object and the pathname string, so you could write the following without
		1571	causing any issues due to C<$path> getting reused:
		1572
		1573	my $path = [$wd, undef];
		1574
		1575	for my $name (qw(abc def ghi)) {
		1576	$path->[1] = $name;
		1577	aio_stat $path, sub {
		1578	# ...
		1579	};
		1580	}
		1581
		1582	There are some caveats: when directories get renamed (or deleted), the
		1583	pathname string doesn't change, so will point to the new directory (or
		1584	nowhere at all), while the directory fd, if available on the system,
		1585	will still point to the original directory. Most functions accepting a
		1586	pathname will use the directory fd on newer systems, and the string on
		1587	older systems. Some functions (such as realpath) will always rely on the
		1588	string form of the pathname.
		1589
		1590	So this functionality is mainly useful to get some protection against
		1591	C<chdir>, to easily get an absolute path out of a relative path for future
		1592	reference, and to speed up doing many operations in the same directory
		1593	(e.g. when stat'ing all files in a directory).
		1594
		1595	The following functions implement this working directory abstraction:
		1596
		1597	=over 4
		1598
		1599	=item aio_wd $pathname, $callback->($wd)
		1600
		1601	Asynchonously canonicalise the given pathname and convert it to an
		1602	IO::AIO::WD object representing it. If possible and supported on the
		1603	system, also open a directory fd to speed up pathname resolution relative
		1604	to this working directory.
		1605
		1606	If something goes wrong, then C<undef> is passwd to the callback instead
		1607	of a working directory object and C<$!> is set appropriately. Since
		1608	passing C<undef> as working directory component of a pathname fails the
		1609	request with C<ENOENT>, there is often no need for error checking in the
		1610	C<aio_wd> callback, as future requests using the value will fail in the
		1611	expected way.
		1612
		1613	=item IO::AIO::CWD
		1614
		1615	This is a compiletime constant (object) that represents the process
		1616	current working directory.
		1617
		1618	Specifying this object as working directory object for a pathname is as if
		1619	the pathname would be specified directly, without a directory object. For
		1620	example, these calls are functionally identical:
		1621
		1622	aio_stat "somefile", sub { ... };
		1623	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1624
		1625	=back
		1626
		1627	To recover the path associated with an IO::AIO::WD object, you can use
		1628	C<aio_realpath>:
		1629
		1630	aio_realpath $wd, sub {
		1631	warn "path is $_[0]\n";
		1632	};
		1633
		1634	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1635	sometimes, fall back to using an absolue path.
1158		1636
1159	=head2 IO::AIO::REQ CLASS	1637	=head2 IO::AIO::REQ CLASS
1160		1638
1161	All non-aggregate C<aio_*> functions return an object of this class when	1639	All non-aggregate C<aio_*> functions return an object of this class when
1162	called in non-void context.	1640	called in non-void context.
…		…
1280		1758
1281	Sets a feeder/generator on this group: every group can have an attached	1759	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,	1760	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,	1761	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,	1762	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,	1763	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1286	delaying any later requests for a long time.	1764	requests, delaying any later requests for a long time.
1287		1765
1288	To avoid this, and allow incremental generation of requests, you can	1766	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	1767	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>,	1768	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	1769	below) requests active in the group itself and is expected to queue more
…		…
1340		1818
1341	See C<poll_cb> for an example.	1819	See C<poll_cb> for an example.
1342		1820
1343	=item IO::AIO::poll_cb	1821	=item IO::AIO::poll_cb
1344		1822
1345	Process some outstanding events on the result pipe. You have to call this	1823	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	1824	been executed but the results are not yet reported). You have to call
1347	returned earlier for whatever reason. Returns immediately when no events	1825	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		1826
		1827	Returns C<0> if all events could be processed (or there were no
		1828	events to process), or C<-1> if it returned earlier for whatever
		1829	reason. Returns immediately when no events are outstanding. The amount
		1830	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1831	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1832
1351	If not all requests were processed for whatever reason, the filehandle	1833	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	1834	descriptor will still be ready when C<poll_cb> returns, so normally you
1353	do anything special to have it called later.	1835	don't have to do anything special to have it called later.
		1836
		1837	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1838	ready, it can be beneficial to call this function from loops which submit
		1839	a lot of requests, to make sure the results get processed when they become
		1840	available and not just when the loop is finished and the event loop takes
		1841	over again. This function returns very fast when there are no outstanding
		1842	requests.
1354		1843
1355	Example: Install an Event watcher that automatically calls	1844	Example: Install an Event watcher that automatically calls
1356	IO::AIO::poll_cb with high priority (more examples can be found in the	1845	IO::AIO::poll_cb with high priority (more examples can be found in the
1357	SYNOPSIS section, at the top of this document):	1846	SYNOPSIS section, at the top of this document):
1358		1847
…		…
1360	poll => 'r', async => 1,	1849	poll => 'r', async => 1,
1361	cb => \&IO::AIO::poll_cb);	1850	cb => \&IO::AIO::poll_cb);
1362		1851
1363	=item IO::AIO::poll_wait	1852	=item IO::AIO::poll_wait
1364		1853
1365	If there are any outstanding requests and none of them in the result	1854	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	1855	requests are outstanding anymore.
1367	does a C<select> on the filehandle. This is useful if you want to	1856
1368	synchronously wait for some requests to finish).	1857	This is useful if you want to synchronously wait for some requests to
		1858	become ready, without actually handling them.
1369		1859
1370	See C<nreqs> for an example.	1860	See C<nreqs> for an example.
1371		1861
1372	=item IO::AIO::poll	1862	=item IO::AIO::poll
1373		1863
…		…
1460		1950
1461	Under normal circumstances you don't need to call this function.	1951	Under normal circumstances you don't need to call this function.
1462		1952
1463	=item IO::AIO::max_idle $nthreads	1953	=item IO::AIO::max_idle $nthreads
1464		1954
1465	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1955	Limit the number of threads (default: 4) that are allowed to idle
1466	threads that did not get a request to process within 10 seconds). That	1956	(i.e., threads that did not get a request to process within the idle
1467	means if a thread becomes idle while C<$nthreads> other threads are also	1957	timeout (default: 10 seconds). That means if a thread becomes idle while
1468	idle, it will free its resources and exit.	1958	C<$nthreads> other threads are also idle, it will free its resources and
		1959	exit.
1469		1960
1470	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1961	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	1962	to allow for extremely high load situations, but want to free resources
1472	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1963	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1473		1964
1474	The default is probably ok in most situations, especially if thread	1965	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	1966	creation is fast. If thread creation is very slow on your system you might
1476	want to use larger values.	1967	want to use larger values.
1477		1968
		1969	=item IO::AIO::idle_timeout $seconds
		1970
		1971	Sets the minimum idle timeout (default 10) after which worker threads are
		1972	allowed to exit. SEe C<IO::AIO::max_idle>.
		1973
1478	=item IO::AIO::max_outstanding $maxreqs	1974	=item IO::AIO::max_outstanding $maxreqs
		1975
		1976	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1977	you do queue up more than this number of requests, the next call to
		1978	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1979	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1980	longer exceeded.
		1981
		1982	In other words, this setting does not enforce a queue limit, but can be
		1983	used to make poll functions block if the limit is exceeded.
1479		1984
1480	This is a very bad function to use in interactive programs because it	1985	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	1986	blocks, and a bad way to reduce concurrency because it is inexact: Better
1482	use an C<aio_group> together with a feed callback.	1987	use an C<aio_group> together with a feed callback.
1483		1988
1484	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1989	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	1990	a lot of files, you can write somehting like this:
1486	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1487	function will block until the limit is no longer exceeded.
1488		1991
1489	The default value is very large, so there is no practical limit on the	1992	IO::AIO::max_outstanding 32;
1490	number of outstanding requests.
1491		1993
1492	You can still queue as many requests as you want. Therefore,	1994	for my $path (...) {
1493	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1995	aio_stat $path , ...;
1494	as a stop gap to shield against fatal memory overflow (with large values).	1996	IO::AIO::poll_cb;
		1997	}
		1998
		1999	IO::AIO::flush;
		2000
		2001	The call to C<poll_cb> inside the loop will normally return instantly, but
		2002	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2003	some requests have been handled. This keeps the loop from pushing a large
		2004	number of C<aio_stat> requests onto the queue.
		2005
		2006	The default value for C<max_outstanding> is very large, so there is no
		2007	practical limit on the number of outstanding requests.
1495		2008
1496	=back	2009	=back
1497		2010
1498	=head3 STATISTICAL INFORMATION	2011	=head3 STATISTICAL INFORMATION
1499		2012
…		…
1521		2034
1522	=back	2035	=back
1523		2036
1524	=head3 MISCELLANEOUS FUNCTIONS	2037	=head3 MISCELLANEOUS FUNCTIONS
1525		2038
1526	IO::AIO implements some functions that might be useful, but are not	2039	IO::AIO implements some functions that are useful when you want to use
1527	asynchronous.	2040	some "Advanced I/O" function not available to in Perl, without going the
		2041	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2042	counterpart.
1528		2043
1529	=over 4	2044	=over 4
1530		2045
1531	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2046	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1532		2047
…		…
1537		2052
1538	Returns the number of bytes copied, or C<-1> on error.	2053	Returns the number of bytes copied, or C<-1> on error.
1539		2054
1540	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2055	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1541		2056
1542	Simply calls the C<posix_fadvise> function (see it's	2057	Simply calls the C<posix_fadvise> function (see its
1543	manpage for details). The following advice constants are	2058	manpage for details). The following advice constants are
1544	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2059	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1545	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2060	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1546	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2061	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1547		2062
1548	On systems that do not implement C<posix_fadvise>, this function returns	2063	On systems that do not implement C<posix_fadvise>, this function returns
1549	ENOSYS, otherwise the return value of C<posix_fadvise>.	2064	ENOSYS, otherwise the return value of C<posix_fadvise>.
1550		2065
		2066	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2067
		2068	Simply calls the C<posix_madvise> function (see its
		2069	manpage for details). The following advice constants are
		2070	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2071	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
		2072	C<IO::AIO::MADV_FREE>.
		2073
		2074	On systems that do not implement C<posix_madvise>, this function returns
		2075	ENOSYS, otherwise the return value of C<posix_madvise>.
		2076
		2077	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2078
		2079	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2080	$scalar (see its manpage for details). The following protect
		2081	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2082	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2083
		2084	On systems that do not implement C<mprotect>, this function returns
		2085	ENOSYS, otherwise the return value of C<mprotect>.
		2086
1551	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2087	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1552		2088
1553	Memory-maps a file (or anonymous memory range) and attaches it to the	2089	Memory-maps a file (or anonymous memory range) and attaches it to the
1554	given C<$scalar>, which will act like a string scalar.	2090	given C<$scalar>, which will act like a string scalar. Returns true on
		2091	success, and false otherwise.
1555		2092
1556	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2093	The only operations allowed on the scalar are C<substr>/C<vec> that don't
1557	change the string length, and most read-only operations such as copying it	2094	change the string length, and most read-only operations such as copying it
1558	or searching it with regexes and so on.	2095	or searching it with regexes and so on.
1559		2096
…		…
1570	filesize.	2107	filesize.
1571		2108
1572	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2109	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1573	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2110	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1574		2111
1575	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2112	C<$flags> can be a combination of
1576	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2113	C<IO::AIO::MAP_SHARED> or
1577	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2114	C<IO::AIO::MAP_PRIVATE>,
		2115	or a number of system-specific flags (when not available, the are C<0>):
1578	(which is set to C<MAP_ANON> if your system only provides this	2116	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1579	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2117	C<IO::AIO::MAP_LOCKED>,
1580	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2118	C<IO::AIO::MAP_NORESERVE>,
		2119	C<IO::AIO::MAP_POPULATE>,
1581	C<IO::AIO::MAP_NONBLOCK>	2120	C<IO::AIO::MAP_NONBLOCK>,
		2121	C<IO::AIO::MAP_FIXED>,
		2122	C<IO::AIO::MAP_GROWSDOWN>,
		2123	C<IO::AIO::MAP_32BIT>,
		2124	C<IO::AIO::MAP_HUGETLB> or
		2125	C<IO::AIO::MAP_STACK>.
1582		2126
1583	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2127	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1584		2128
		2129	C<$offset> is the offset from the start of the file - it generally must be
		2130	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2131
		2132	Example:
		2133
		2134	use Digest::MD5;
		2135	use IO::AIO;
		2136
		2137	open my $fh, "<verybigfile"
		2138	or die "$!";
		2139
		2140	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2141	or die "verybigfile: $!";
		2142
		2143	my $fast_md5 = md5 $data;
		2144
1585	=item IO::AIO::munmap $scalar	2145	=item IO::AIO::munmap $scalar
1586		2146
1587	Removes a previous mmap and undefines the C<$scalar>.	2147	Removes a previous mmap and undefines the C<$scalar>.
1588		2148
1589	=item IO::AIO::mlockall $flags	2149	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1590		2150
1591	Calls the C<mlockall> function with the given C<$flags> (a combination of	2151	Calls the C<munlock> function, undoing the effects of a previous
1592	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL__FUTURE>).	2152	C<aio_mlock> call (see its description for details).
1593
1594	On systems that do not implement C<mlockall>, this function returns
1595	ENOSYS, otherwise the return value of C<mlockall>.
1596		2153
1597	=item IO::AIO::munlockall	2154	=item IO::AIO::munlockall
1598		2155
1599	Calls the C<munlockall> function.	2156	Calls the C<munlockall> function.
1600		2157
1601	On systems that do not implement C<munlockall>, this function returns	2158	On systems that do not implement C<munlockall>, this function returns
1602	ENOSYS, otherwise the return value of C<munlockall>.	2159	ENOSYS, otherwise the return value of C<munlockall>.
		2160
		2161	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2162
		2163	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2164	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2165	should be the file offset.
		2166
		2167	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2168	silently corrupt the data in this case.
		2169
		2170	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2171	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2172	C<IO::AIO::SPLICE_F_GIFT>.
		2173
		2174	See the C<splice(2)> manpage for details.
		2175
		2176	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2177
		2178	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2179	description for C<IO::AIO::splice> above for details.
		2180
		2181	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2182
		2183	Attempts to query or change the pipe buffer size. Obviously works only
		2184	on pipes, and currently works only on GNU/Linux systems, and fails with
		2185	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2186	size on other systems, drop me a note.
		2187
		2188	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2189
		2190	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2191	C<$flags> is missing or C<0>, then this should be the same as a call to
		2192	perl's built-in C<pipe> function and create a new pipe, and works on
		2193	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2194	(..., 4096, O_BINARY)>.
		2195
		2196	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2197	the given flags (Linux 2.6.27, glibc 2.9).
		2198
		2199	On success, the read and write file handles are returned.
		2200
		2201	On error, nothing will be returned. If the pipe2 syscall is missing and
		2202	C<$flags> is non-zero, fails with C<ENOSYS>.
		2203
		2204	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2205	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2206	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1603		2207
1604	=back	2208	=back
1605		2209
1606	=cut	2210	=cut
1607		2211
…		…
1642	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2246	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1643	\&IO::AIO::poll_cb);	2247	\&IO::AIO::poll_cb);
1644		2248
1645	=head2 FORK BEHAVIOUR	2249	=head2 FORK BEHAVIOUR
1646		2250
1647	This module should do "the right thing" when the process using it forks:	2251	Usage of pthreads in a program changes the semantics of fork
		2252	considerably. Specifically, only async-safe functions can be called after
		2253	fork. Perl doesn't know about this, so in general, you cannot call fork
		2254	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2255	pthreads, so this applies, but many other extensions and (for inexplicable
		2256	reasons) perl itself often is linked against pthreads, so this limitation
		2257	applies to quite a lot of perls.
1648		2258
1649	Before the fork, IO::AIO enters a quiescent state where no requests	2259	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1650	can be added in other threads and no results will be processed. After	2260	only works in the process that loaded it. Forking is fully supported, but
1651	the fork the parent simply leaves the quiescent state and continues	2261	using IO::AIO in the child is not.
1652	request/result processing, while the child frees the request/result queue
1653	(so that the requests started before the fork will only be handled in the
1654	parent). Threads will be started on demand until the limit set in the
1655	parent process has been reached again.
1656		2262
1657	In short: the parent will, after a short pause, continue as if fork had	2263	You might get around by not I<using> IO::AIO before (or after)
1658	not been called, while the child will act as if IO::AIO has not been used	2264	forking. You could also try to call the L<IO::AIO::reinit> function in the
1659	yet.	2265	child:
		2266
		2267	=over 4
		2268
		2269	=item IO::AIO::reinit
		2270
		2271	Abandons all current requests and I/O threads and simply reinitialises all
		2272	data structures. This is not an operation supported by any standards, but
		2273	happens to work on GNU/Linux and some newer BSD systems.
		2274
		2275	The only reasonable use for this function is to call it after forking, if
		2276	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2277	the process will result in undefined behaviour. Calling it at any time
		2278	will also result in any undefined (by POSIX) behaviour.
		2279
		2280	=back
1660		2281
1661	=head2 MEMORY USAGE	2282	=head2 MEMORY USAGE
1662		2283
1663	Per-request usage:	2284	Per-request usage:
1664		2285

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