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Revision 1.199 by root, Wed Jun 29 12:46:36 2011 UTC vs.
Revision 1.287 by root, Tue Jul 24 04:58:59 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 = '3.92';	176	our $VERSION = 4.42;
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_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
183	aio_statvfs);	187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
184		190
185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
187	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
188	nreqs nready npending nthreads	194	nreqs nready npending nthreads
189	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
190	sendfile fadvise madvise	196	sendfile fadvise madvise
191	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall);
192		198
193	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
194		200
195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
196		202
…		…
200		206
201	=head1 FUNCTIONS	207	=head1 FUNCTIONS
202		208
203	=head2 QUICK OVERVIEW	209	=head2 QUICK OVERVIEW
204		210
205	This section simply lists the prototypes of the most important functions	211	This section simply lists the prototypes most of the functions for
206	for quick reference. See the following sections for function-by-function	212	quick reference. See the following sections for function-by-function
207	documentation.	213	documentation.
208		214
		215	aio_wd $pathname, $callback->($wd)
209	aio_open $pathname, $flags, $mode, $callback->($fh)	216	aio_open $pathname, $flags, $mode, $callback->($fh)
210	aio_close $fh, $callback->($status)	217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214	aio_readahead $fh,$offset,$length, $callback->($retval)	222	aio_readahead $fh,$offset,$length, $callback->($retval)
215	aio_stat $fh_or_path, $callback->($status)	223	aio_stat $fh_or_path, $callback->($status)
216	aio_lstat $fh, $callback->($status)	224	aio_lstat $fh, $callback->($status)
217	aio_statvfs $fh_or_path, $callback->($statvfs)	225	aio_statvfs $fh_or_path, $callback->($statvfs)
218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219	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)
220	aio_truncate $fh_or_path, $offset, $callback->($status)	229	aio_truncate $fh_or_path, $offset, $callback->($status)
221	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)
222	aio_unlink $pathname, $callback->($status)	232	aio_unlink $pathname, $callback->($status)
223	aio_mknod $path, $mode, $dev, $callback->($status)	233	aio_mknod $pathname, $mode, $dev, $callback->($status)
224	aio_link $srcpath, $dstpath, $callback->($status)	234	aio_link $srcpath, $dstpath, $callback->($status)
225	aio_symlink $srcpath, $dstpath, $callback->($status)	235	aio_symlink $srcpath, $dstpath, $callback->($status)
226	aio_readlink $path, $callback->($link)	236	aio_readlink $pathname, $callback->($link)
		237	aio_realpath $pathname, $callback->($path)
227	aio_rename $srcpath, $dstpath, $callback->($status)	238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
228	aio_mkdir $pathname, $mode, $callback->($status)	240	aio_mkdir $pathname, $mode, $callback->($status)
229	aio_rmdir $pathname, $callback->($status)	241	aio_rmdir $pathname, $callback->($status)
230	aio_readdir $pathname, $callback->($entries)	242	aio_readdir $pathname, $callback->($entries)
231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233	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)
234	aio_load $path, $data, $callback->($status)	247	aio_load $pathname, $data, $callback->($status)
235	aio_copy $srcpath, $dstpath, $callback->($status)	248	aio_copy $srcpath, $dstpath, $callback->($status)
236	aio_move $srcpath, $dstpath, $callback->($status)	249	aio_move $srcpath, $dstpath, $callback->($status)
237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238	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)
239	aio_sync $callback->($status)	253	aio_sync $callback->($status)
		254	aio_syncfs $fh, $callback->($status)
240	aio_fsync $fh, $callback->($status)	255	aio_fsync $fh, $callback->($status)
241	aio_fdatasync $fh, $callback->($status)	256	aio_fdatasync $fh, $callback->($status)
242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243	aio_pathsync $path, $callback->($status)	258	aio_pathsync $pathname, $callback->($status)
244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247	aio_mlockall $flags, $callback->($status)	262	aio_mlockall $flags, $callback->($status)
248	aio_group $callback->(...)	263	aio_group $callback->(...)
249	aio_nop $callback->()	264	aio_nop $callback->()
…		…
263	IO::AIO::idle_timeout $seconds	278	IO::AIO::idle_timeout $seconds
264	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
265	IO::AIO::nreqs	280	IO::AIO::nreqs
266	IO::AIO::nready	281	IO::AIO::nready
267	IO::AIO::npending	282	IO::AIO::npending
		283	$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
		284	IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
268		285
269	IO::AIO::sendfile $ofh, $ifh, $offset, $count	286	IO::AIO::sendfile $ofh, $ifh, $offset, $count
270	IO::AIO::fadvise $fh, $offset, $len, $advice	287	IO::AIO::fadvise $fh, $offset, $len, $advice
		288	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		289	IO::AIO::munmap $scalar
		290	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
271	IO::AIO::madvise $scalar, $offset, $length, $advice	291	IO::AIO::madvise $scalar, $offset, $length, $advice
272	IO::AIO::mprotect $scalar, $offset, $length, $protect	292	IO::AIO::mprotect $scalar, $offset, $length, $protect
273	IO::AIO::munlock $scalar, $offset = 0, $length = undef	293	IO::AIO::munlock $scalar, $offset = 0, $length = undef
274	IO::AIO::munlockall	294	IO::AIO::munlockall
275		295
276	=head2 AIO REQUEST FUNCTIONS	296	=head2 API NOTES
277		297
278	All the C<aio_*> calls are more or less thin wrappers around the syscall	298	All the C<aio_*> calls are more or less thin wrappers around the syscall
279	with the same name (sans C<aio_>). The arguments are similar or identical,	299	with the same name (sans C<aio_>). The arguments are similar or identical,
280	and they all accept an additional (and optional) C<$callback> argument	300	and they all accept an additional (and optional) C<$callback> argument
281	which must be a code reference. This code reference will get called with	301	which must be a code reference. This code reference will be called after
282	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	302	the syscall has been executed in an asynchronous fashion. The results
283	perl, which usually delivers "false") as its sole argument after the given	303	of the request will be passed as arguments to the callback (and, if an
284	syscall has been executed asynchronously.	304	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		305	most syscalls return C<-1> on error, unlike perl, which usually delivers
		306	"false").
		307
		308	Some requests (such as C<aio_readdir>) pass the actual results and
		309	communicate failures by passing C<undef>.
285		310
286	All functions expecting a filehandle keep a copy of the filehandle	311	All functions expecting a filehandle keep a copy of the filehandle
287	internally until the request has finished.	312	internally until the request has finished.
288		313
289	All functions return request objects of type L<IO::AIO::REQ> that allow	314	All functions return request objects of type L<IO::AIO::REQ> that allow
290	further manipulation of those requests while they are in-flight.	315	further manipulation of those requests while they are in-flight.
291		316
292	The pathnames you pass to these routines I<must> be absolute and	317	The pathnames you pass to these routines I<should> be absolute. The
293	encoded as octets. The reason for the former is that at the time the	318	reason for this is that at the time the request is being executed, the
294	request is being executed, the current working directory could have	319	current working directory could have changed. Alternatively, you can
295	changed. Alternatively, you can make sure that you never change the	320	make sure that you never change the current working directory anywhere
296	current working directory anywhere in the program and then use relative	321	in the program and then use relative paths. You can also take advantage
297	paths.	322	of IO::AIOs working directory abstraction, that lets you specify paths
		323	relative to some previously-opened "working directory object" - see the
		324	description of the C<IO::AIO::WD> class later in this document.
298		325
299	To encode pathnames as octets, either make sure you either: a) always pass	326	To encode pathnames as octets, either make sure you either: a) always pass
300	in filenames you got from outside (command line, readdir etc.) without	327	in filenames you got from outside (command line, readdir etc.) without
301	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	328	tinkering, b) are in your native filesystem encoding, c) use the Encode
302	your pathnames to the locale (or other) encoding in effect in the user	329	module and encode your pathnames to the locale (or other) encoding in
303	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	330	effect in the user environment, d) use Glib::filename_from_unicode on
304	use something else to ensure your scalar has the correct contents.	331	unicode filenames or e) use something else to ensure your scalar has the
		332	correct contents.
305		333
306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	334	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
307	handles correctly whether it is set or not.	335	handles correctly whether it is set or not.
		336
		337	=head2 AIO REQUEST FUNCTIONS
308		338
309	=over 4	339	=over 4
310		340
311	=item $prev_pri = aioreq_pri [$pri]	341	=item $prev_pri = aioreq_pri [$pri]
312		342
…		…
342		372
343		373
344	=item aio_open $pathname, $flags, $mode, $callback->($fh)	374	=item aio_open $pathname, $flags, $mode, $callback->($fh)
345		375
346	Asynchronously open or create a file and call the callback with a newly	376	Asynchronously open or create a file and call the callback with a newly
347	created filehandle for the file.	377	created filehandle for the file (or C<undef> in case of an error).
348		378
349	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	379	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
350	for an explanation.	380	for an explanation.
351		381
352	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	382	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
375	following POSIX and non-POSIX constants are available (missing ones on	405	following POSIX and non-POSIX constants are available (missing ones on
376	your system are, as usual, C<0>):	406	your system are, as usual, C<0>):
377		407
378	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	408	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
379	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	409	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
380	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	410	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
381		411
382		412
383	=item aio_close $fh, $callback->($status)	413	=item aio_close $fh, $callback->($status)
384		414
385	Asynchronously close a file and call the callback with the result	415	Asynchronously close a file and call the callback with the result
…		…
395	Or in other words: the file descriptor will be closed, but it will not be	425	Or in other words: the file descriptor will be closed, but it will not be
396	free for reuse until the perl filehandle is closed.	426	free for reuse until the perl filehandle is closed.
397		427
398	=cut	428	=cut
399		429
		430	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		431
		432	Seeks the filehandle to the new C<$offset>, similarly to perl's
		433	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		434	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		435	C<IO::AIO::SEEK_END>).
		436
		437	The resulting absolute offset will be passed to the callback, or C<-1> in
		438	case of an error.
		439
		440	In theory, the C<$whence> constants could be different than the
		441	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		442	so don't panic.
		443
		444	As a GNU/Linux (and maybe Solaris) extension, also the constants
		445	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		446	could be found. No guarantees about suitability for use in C<aio_seek> or
		447	Perl's C<sysseek> can be made though, although I would naively assume they
		448	"just work".
		449
400	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	450	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
401		451
402	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	452	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
403		453
404	Reads or writes C<$length> bytes from or to the specified C<$fh> and	454	Reads or writes C<$length> bytes from or to the specified C<$fh> and
405	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	455	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
406	and calls the callback without the actual number of bytes read (or -1 on	456	calls the callback with the actual number of bytes transferred (or -1 on
407	error, just like the syscall).	457	error, just like the syscall).
408		458
409	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	459	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
410	offset plus the actual number of bytes read.	460	offset plus the actual number of bytes read.
411		461
…		…
469	As native sendfile syscalls (as practically any non-POSIX interface hacked	519	As native sendfile syscalls (as practically any non-POSIX interface hacked
470	together in a hurry to improve benchmark numbers) tend to be rather buggy	520	together in a hurry to improve benchmark numbers) tend to be rather buggy
471	on many systems, this implementation tries to work around some known bugs	521	on many systems, this implementation tries to work around some known bugs
472	in Linux and FreeBSD kernels (probably others, too), but that might fail,	522	in Linux and FreeBSD kernels (probably others, too), but that might fail,
473	so you really really should check the return value of C<aio_sendfile> -	523	so you really really should check the return value of C<aio_sendfile> -
474	fewre bytes than expected might have been transferred.	524	fewer bytes than expected might have been transferred.
475		525
476		526
477	=item aio_readahead $fh,$offset,$length, $callback->($retval)	527	=item aio_readahead $fh,$offset,$length, $callback->($retval)
478		528
479	C<aio_readahead> populates the page cache with data from a file so that	529	C<aio_readahead> populates the page cache with data from a file so that
…		…
483	whole pages, so that offset is effectively rounded down to a page boundary	533	whole pages, so that offset is effectively rounded down to a page boundary
484	and bytes are read up to the next page boundary greater than or equal to	534	and bytes are read up to the next page boundary greater than or equal to
485	(off-set+length). C<aio_readahead> does not read beyond the end of the	535	(off-set+length). C<aio_readahead> does not read beyond the end of the
486	file. The current file offset of the file is left unchanged.	536	file. The current file offset of the file is left unchanged.
487		537
488	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	538	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
489	emulated by simply reading the data, which would have a similar effect.	539	be emulated by simply reading the data, which would have a similar effect.
490		540
491		541
492	=item aio_stat $fh_or_path, $callback->($status)	542	=item aio_stat $fh_or_path, $callback->($status)
493		543
494	=item aio_lstat $fh, $callback->($status)	544	=item aio_lstat $fh, $callback->($status)
…		…
563	namemax => 255,	613	namemax => 255,
564	frsize => 1024,	614	frsize => 1024,
565	fsid => 1810	615	fsid => 1810
566	}	616	}
567		617
568
569	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	618	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
570		619
571	Works like perl's C<utime> function (including the special case of $atime	620	Works like perl's C<utime> function (including the special case of $atime
572	and $mtime being undef). Fractional times are supported if the underlying	621	and $mtime being undef). Fractional times are supported if the underlying
573	syscalls support them.	622	syscalls support them.
…		…
600	=item aio_truncate $fh_or_path, $offset, $callback->($status)	649	=item aio_truncate $fh_or_path, $offset, $callback->($status)
601		650
602	Works like truncate(2) or ftruncate(2).	651	Works like truncate(2) or ftruncate(2).
603		652
604		653
		654	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		655
		656	Allocates or frees disk space according to the C<$mode> argument. See the
		657	linux C<fallocate> documentation for details.
		658
		659	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		660	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		661	to deallocate a file range.
		662
		663	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		664	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		665	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		666	to unshare shared blocks (see your L<fallocate(2)> manpage).
		667
		668	The file system block size used by C<fallocate> is presumably the
		669	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		670	can dictate other limitations.
		671
		672	If C<fallocate> isn't available or cannot be emulated (currently no
		673	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		674
		675
605	=item aio_chmod $fh_or_path, $mode, $callback->($status)	676	=item aio_chmod $fh_or_path, $mode, $callback->($status)
606		677
607	Works like perl's C<chmod> function.	678	Works like perl's C<chmod> function.
608		679
609		680
…		…
611		682
612	Asynchronously unlink (delete) a file and call the callback with the	683	Asynchronously unlink (delete) a file and call the callback with the
613	result code.	684	result code.
614		685
615		686
616	=item aio_mknod $path, $mode, $dev, $callback->($status)	687	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
617		688
618	[EXPERIMENTAL]	689	[EXPERIMENTAL]
619		690
620	Asynchronously create a device node (or fifo). See mknod(2).	691	Asynchronously create a device node (or fifo). See mknod(2).
621		692
622	The only (POSIX-) portable way of calling this function is:	693	The only (POSIX-) portable way of calling this function is:
623		694
624	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	695	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
625		696
626	See C<aio_stat> for info about some potentially helpful extra constants	697	See C<aio_stat> for info about some potentially helpful extra constants
627	and functions.	698	and functions.
628		699
629	=item aio_link $srcpath, $dstpath, $callback->($status)	700	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
636		707
637	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	708	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
638	the path C<$dstpath> and call the callback with the result code.	709	the path C<$dstpath> and call the callback with the result code.
639		710
640		711
641	=item aio_readlink $path, $callback->($link)	712	=item aio_readlink $pathname, $callback->($link)
642		713
643	Asynchronously read the symlink specified by C<$path> and pass it to	714	Asynchronously read the symlink specified by C<$path> and pass it to
644	the callback. If an error occurs, nothing or undef gets passed to the	715	the callback. If an error occurs, nothing or undef gets passed to the
645	callback.	716	callback.
646		717
647		718
		719	=item aio_realpath $pathname, $callback->($path)
		720
		721	Asynchronously make the path absolute and resolve any symlinks in
		722	C<$path>. The resulting path only consists of directories (same as
		723	L<Cwd::realpath>).
		724
		725	This request can be used to get the absolute path of the current working
		726	directory by passing it a path of F<.> (a single dot).
		727
		728
648	=item aio_rename $srcpath, $dstpath, $callback->($status)	729	=item aio_rename $srcpath, $dstpath, $callback->($status)
649		730
650	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	731	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
651	rename(2) and call the callback with the result code.	732	rename(2) and call the callback with the result code.
		733
		734	On systems that support the AIO::WD working directory abstraction
		735	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		736	of failing, C<rename> is called on the absolute path of C<$wd>.
		737
		738
		739	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		740
		741	Basically a version of C<aio_rename> with an additional C<$flags>
		742	argument. Calling this with C<$flags=0> is the same as calling
		743	C<aio_rename>.
		744
		745	Non-zero flags are currently only supported on GNU/Linux systems that
		746	support renameat2. Other systems fail with C<ENOSYS> in this case.
		747
		748	The following constants are available (missing ones are, as usual C<0>),
		749	see renameat2(2) for details:
		750
		751	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		752	and C<IO::AIO::RENAME_WHITEOUT>.
652		753
653		754
654	=item aio_mkdir $pathname, $mode, $callback->($status)	755	=item aio_mkdir $pathname, $mode, $callback->($status)
655		756
656	Asynchronously mkdir (create) a directory and call the callback with	757	Asynchronously mkdir (create) a directory and call the callback with
…		…
661	=item aio_rmdir $pathname, $callback->($status)	762	=item aio_rmdir $pathname, $callback->($status)
662		763
663	Asynchronously rmdir (delete) a directory and call the callback with the	764	Asynchronously rmdir (delete) a directory and call the callback with the
664	result code.	765	result code.
665		766
		767	On systems that support the AIO::WD working directory abstraction
		768	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		769	C<rmdir> is called on the absolute path of C<$wd>.
		770
666		771
667	=item aio_readdir $pathname, $callback->($entries)	772	=item aio_readdir $pathname, $callback->($entries)
668		773
669	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	774	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
670	directory (i.e. opendir + readdir + closedir). The entries will not be	775	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
674	array-ref with the filenames.	779	array-ref with the filenames.
675		780
676		781
677	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	782	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
678		783
679	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	784	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
680	behaviour and output format. In case of an error, C<$entries> will be	785	tune behaviour and output format. In case of an error, C<$entries> will be
681	C<undef>.	786	C<undef>.
682		787
683	The flags are a combination of the following constants, ORed together (the	788	The flags are a combination of the following constants, ORed together (the
684	flags will also be passed to the callback, possibly modified):	789	flags will also be passed to the callback, possibly modified):
685		790
686	=over 4	791	=over 4
687		792
688	=item IO::AIO::READDIR_DENTS	793	=item IO::AIO::READDIR_DENTS
689		794
690	When this flag is off, then the callback gets an arrayref consisting of	795	Normally the callback gets an arrayref consisting of names only (as
691	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	796	with C<aio_readdir>). If this flag is set, then the callback gets an
692	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	797	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
693	entry in more detail.	798	single directory entry in more detail:
694		799
695	C<$name> is the name of the entry.	800	C<$name> is the name of the entry.
696		801
697	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	802	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
698		803
699	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	804	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
700	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	805	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
701	C<IO::AIO::DT_WHT>.	806	C<IO::AIO::DT_WHT>.
702		807
703	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	808	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
704	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	809	to know, you have to run stat yourself. Also, for speed/memory reasons,
705	scalars are read-only: you can not modify them.	810	the C<$type> scalars are read-only: you must not modify them.
706		811
707	C<$inode> is the inode number (which might not be exact on systems with 64	812	C<$inode> is the inode number (which might not be exact on systems with 64
708	bit inode numbers and 32 bit perls). This field has unspecified content on	813	bit inode numbers and 32 bit perls). This field has unspecified content on
709	systems that do not deliver the inode information.	814	systems that do not deliver the inode information.
710		815
…		…
721	short names are tried first.	826	short names are tried first.
722		827
723	=item IO::AIO::READDIR_STAT_ORDER	828	=item IO::AIO::READDIR_STAT_ORDER
724		829
725	When this flag is set, then the names will be returned in an order	830	When this flag is set, then the names will be returned in an order
726	suitable for stat()'ing each one. That is, when you plan to stat()	831	suitable for stat()'ing each one. That is, when you plan to stat() most or
727	all files in the given directory, then the returned order will likely	832	all files in the given directory, then the returned order will likely be
728	be fastest.	833	faster.
729		834
730	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	835	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
731	the likely dirs come first, resulting in a less optimal stat order.	836	then the likely dirs come first, resulting in a less optimal stat order
		837	for stat'ing all entries, but likely a more optimal order for finding
		838	subdirectories.
732		839
733	=item IO::AIO::READDIR_FOUND_UNKNOWN	840	=item IO::AIO::READDIR_FOUND_UNKNOWN
734		841
735	This flag should not be set when calling C<aio_readdirx>. Instead, it	842	This flag should not be set when calling C<aio_readdirx>. Instead, it
736	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	843	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
737	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	844	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
738	C<$type>'s are known, which can be used to speed up some algorithms.	845	C<$type>'s are known, which can be used to speed up some algorithms.
739		846
740	=back	847	=back
741		848
742		849
		850	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		851
		852	Opens, reads and closes the given file. The data is put into C<$data>,
		853	which is resized as required.
		854
		855	If C<$offset> is negative, then it is counted from the end of the file.
		856
		857	If C<$length> is zero, then the remaining length of the file is
		858	used. Also, in this case, the same limitations to modifying C<$data> apply
		859	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		860	with C<substr>. If the size of the file is known, specifying a non-zero
		861	C<$length> results in a performance advantage.
		862
		863	This request is similar to the older C<aio_load> request, but since it is
		864	a single request, it might be more efficient to use.
		865
		866	Example: load F</etc/passwd> into C<$passwd>.
		867
		868	my $passwd;
		869	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		870	$_[0] >= 0
		871	or die "/etc/passwd: $!\n";
		872
		873	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		874	print $passwd;
		875	};
		876	IO::AIO::flush;
		877
		878
743	=item aio_load $path, $data, $callback->($status)	879	=item aio_load $pathname, $data, $callback->($status)
744		880
745	This is a composite request that tries to fully load the given file into	881	This is a composite request that tries to fully load the given file into
746	memory. Status is the same as with aio_read.	882	memory. Status is the same as with aio_read.
		883
		884	Using C<aio_slurp> might be more efficient, as it is a single request.
747		885
748	=cut	886	=cut
749		887
750	sub aio_load($$;$) {	888	sub aio_load($$;$) {
751	my ($path, undef, $cb) = @_;	889	my ($path, undef, $cb) = @_;
…		…
771	=item aio_copy $srcpath, $dstpath, $callback->($status)	909	=item aio_copy $srcpath, $dstpath, $callback->($status)
772		910
773	Try to copy the I<file> (directories not supported as either source or	911	Try to copy the I<file> (directories not supported as either source or
774	destination) from C<$srcpath> to C<$dstpath> and call the callback with	912	destination) from C<$srcpath> to C<$dstpath> and call the callback with
775	a status of C<0> (ok) or C<-1> (error, see C<$!>).	913	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		914
		915	Existing destination files will be truncated.
776		916
777	This is a composite request that creates the destination file with	917	This is a composite request that creates the destination file with
778	mode 0200 and copies the contents of the source file into it using	918	mode 0200 and copies the contents of the source file into it using
779	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	919	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
780	uid/gid, in that order.	920	uid/gid, in that order.
…		…
883	};	1023	};
884		1024
885	$grp	1025	$grp
886	}	1026	}
887		1027
888	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1028	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
889		1029
890	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1030	Scans a directory (similar to C<aio_readdir>) but additionally tries to
891	efficiently separate the entries of directory C<$path> into two sets of	1031	efficiently separate the entries of directory C<$path> into two sets of
892	names, directories you can recurse into (directories), and ones you cannot	1032	names, directories you can recurse into (directories), and ones you cannot
893	recurse into (everything else, including symlinks to directories).	1033	recurse into (everything else, including symlinks to directories).
894		1034
895	C<aio_scandir> is a composite request that creates of many sub requests_	1035	C<aio_scandir> is a composite request that generates many sub requests.
896	C<$maxreq> specifies the maximum number of outstanding aio requests that	1036	C<$maxreq> specifies the maximum number of outstanding aio requests that
897	this function generates. If it is C<< <= 0 >>, then a suitable default	1037	this function generates. If it is C<< <= 0 >>, then a suitable default
898	will be chosen (currently 4).	1038	will be chosen (currently 4).
899		1039
900	On error, the callback is called without arguments, otherwise it receives	1040	On error, the callback is called without arguments, otherwise it receives
…		…
924	Then entries will be sorted into likely directories a non-initial dot	1064	Then entries will be sorted into likely directories a non-initial dot
925	currently) and likely non-directories (see C<aio_readdirx>). Then every	1065	currently) and likely non-directories (see C<aio_readdirx>). Then every
926	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1066	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
927	in order of their inode numbers. If that succeeds, it assumes that the	1067	in order of their inode numbers. If that succeeds, it assumes that the
928	entry is a directory or a symlink to directory (which will be checked	1068	entry is a directory or a symlink to directory (which will be checked
929	seperately). This is often faster than stat'ing the entry itself because	1069	separately). This is often faster than stat'ing the entry itself because
930	filesystems might detect the type of the entry without reading the inode	1070	filesystems might detect the type of the entry without reading the inode
931	data (e.g. ext2fs filetype feature), even on systems that cannot return	1071	data (e.g. ext2fs filetype feature), even on systems that cannot return
932	the filetype information on readdir.	1072	the filetype information on readdir.
933		1073
934	If the known number of directories (link count - 2) has been reached, the	1074	If the known number of directories (link count - 2) has been reached, the
…		…
950		1090
951	my $grp = aio_group $cb;	1091	my $grp = aio_group $cb;
952		1092
953	$maxreq = 4 if $maxreq <= 0;	1093	$maxreq = 4 if $maxreq <= 0;
954		1094
955	# stat once	1095	# get a wd object
956	aioreq_pri $pri;	1096	aioreq_pri $pri;
957	add $grp aio_stat $path, sub {	1097	add $grp aio_wd $path, sub {
		1098	$_[0]
958	return $grp->result () if $_[0];	1099	or return $grp->result ();
959	my $now = time;
960	my $hash1 = join ":", (stat _)[0,1,3,7,9];
961		1100
962	# read the directory entries	1101	my $wd = [shift, "."];
		1102
		1103	# stat once
963	aioreq_pri $pri;	1104	aioreq_pri $pri;
964	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1105	add $grp aio_stat $wd, sub {
965	my $entries = shift
966	or return $grp->result ();	1106	return $grp->result () if $_[0];
		1107	my $now = time;
		1108	my $hash1 = join ":", (stat _)[0,1,3,7,9];
967		1109
968	# stat the dir another time	1110	# read the directory entries
969	aioreq_pri $pri;	1111	aioreq_pri $pri;
		1112	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1113	my $entries = shift
		1114	or return $grp->result ();
		1115
		1116	# stat the dir another time
		1117	aioreq_pri $pri;
970	add $grp aio_stat $path, sub {	1118	add $grp aio_stat $wd, sub {
971	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1119	my $hash2 = join ":", (stat _)[0,1,3,7,9];
972		1120
973	my $ndirs;	1121	my $ndirs;
974		1122
975	# take the slow route if anything looks fishy	1123	# take the slow route if anything looks fishy
976	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1124	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
977	$ndirs = -1;	1125	$ndirs = -1;
978	} else {	1126	} else {
979	# if nlink == 2, we are finished	1127	# if nlink == 2, we are finished
980	# for non-posix-fs's, we rely on nlink < 2	1128	# for non-posix-fs's, we rely on nlink < 2
981	$ndirs = (stat _)[3] - 2	1129	$ndirs = (stat _)[3] - 2
982	or return $grp->result ([], $entries);	1130	or return $grp->result ([], $entries);
983	}	1131	}
984		1132
985	my (@dirs, @nondirs);	1133	my (@dirs, @nondirs);
986		1134
987	my $statgrp = add $grp aio_group sub {	1135	my $statgrp = add $grp aio_group sub {
988	$grp->result (\@dirs, \@nondirs);	1136	$grp->result (\@dirs, \@nondirs);
989	};	1137	};
990		1138
991	limit $statgrp $maxreq;	1139	limit $statgrp $maxreq;
992	feed $statgrp sub {	1140	feed $statgrp sub {
993	return unless @$entries;	1141	return unless @$entries;
994	my $entry = shift @$entries;	1142	my $entry = shift @$entries;
995		1143
996	aioreq_pri $pri;	1144	aioreq_pri $pri;
		1145	$wd->[1] = "$entry/.";
997	add $statgrp aio_stat "$path/$entry/.", sub {	1146	add $statgrp aio_stat $wd, sub {
998	if ($_[0] < 0) {	1147	if ($_[0] < 0) {
999	push @nondirs, $entry;	1148	push @nondirs, $entry;
1000	} else {	1149	} else {
1001	# need to check for real directory	1150	# need to check for real directory
1002	aioreq_pri $pri;	1151	aioreq_pri $pri;
		1152	$wd->[1] = $entry;
1003	add $statgrp aio_lstat "$path/$entry", sub {	1153	add $statgrp aio_lstat $wd, sub {
1004	if (-d _) {	1154	if (-d _) {
1005	push @dirs, $entry;	1155	push @dirs, $entry;
1006		1156
1007	unless (--$ndirs) {	1157	unless (--$ndirs) {
1008	push @nondirs, @$entries;	1158	push @nondirs, @$entries;
1009	feed $statgrp;	1159	feed $statgrp;
		1160	}
		1161	} else {
		1162	push @nondirs, $entry;
1010	}	1163	}
1011	} else {
1012	push @nondirs, $entry;
1013	}	1164	}
1014	}	1165	}
1015	}	1166	};
1016	};	1167	};
1017	};	1168	};
1018	};	1169	};
1019	};	1170	};
1020	};	1171	};
1021		1172
1022	$grp	1173	$grp
1023	}	1174	}
1024		1175
1025	=item aio_rmtree $path, $callback->($status)	1176	=item aio_rmtree $pathname, $callback->($status)
1026		1177
1027	Delete a directory tree starting (and including) C<$path>, return the	1178	Delete a directory tree starting (and including) C<$path>, return the
1028	status of the final C<rmdir> only. This is a composite request that	1179	status of the final C<rmdir> only. This is a composite request that
1029	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1180	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1030	everything else.	1181	everything else.
1031		1182
1032	=cut	1183	=cut
1033		1184
…		…
1055	};	1206	};
1056		1207
1057	$grp	1208	$grp
1058	}	1209	}
1059		1210
		1211	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1212
		1213	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1214
		1215	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1216	they execute asynchronously and pass the return value to the callback.
		1217
		1218	Both calls can be used for a lot of things, some of which make more sense
		1219	to run asynchronously in their own thread, while some others make less
		1220	sense. For example, calls that block waiting for external events, such
		1221	as locking, will also lock down an I/O thread while it is waiting, which
		1222	can deadlock the whole I/O system. At the same time, there might be no
		1223	alternative to using a thread to wait.
		1224
		1225	So in general, you should only use these calls for things that do
		1226	(filesystem) I/O, not for things that wait for other events (network,
		1227	other processes), although if you are careful and know what you are doing,
		1228	you still can.
		1229
		1230	The following constants are available (missing ones are, as usual C<0>):
		1231
		1232	C<F_DUPFD_CLOEXEC>,
		1233
		1234	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1235
		1236	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1237
		1238	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1239	C<FS_IOC_FIEMAP>.
		1240
		1241	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1242	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1243
		1244	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1245	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1246	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1247	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1248	C<FS_FL_USER_MODIFIABLE>.
		1249
		1250	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1251	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1252	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1253	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1254
1060	=item aio_sync $callback->($status)	1255	=item aio_sync $callback->($status)
1061		1256
1062	Asynchronously call sync and call the callback when finished.	1257	Asynchronously call sync and call the callback when finished.
1063		1258
1064	=item aio_fsync $fh, $callback->($status)	1259	=item aio_fsync $fh, $callback->($status)
…		…
1071	Asynchronously call fdatasync on the given filehandle and call the	1266	Asynchronously call fdatasync on the given filehandle and call the
1072	callback with the fdatasync result code.	1267	callback with the fdatasync result code.
1073		1268
1074	If this call isn't available because your OS lacks it or it couldn't be	1269	If this call isn't available because your OS lacks it or it couldn't be
1075	detected, it will be emulated by calling C<fsync> instead.	1270	detected, it will be emulated by calling C<fsync> instead.
		1271
		1272	=item aio_syncfs $fh, $callback->($status)
		1273
		1274	Asynchronously call the syncfs syscall to sync the filesystem associated
		1275	to the given filehandle and call the callback with the syncfs result
		1276	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1277	errno to C<ENOSYS> nevertheless.
1076		1278
1077	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1279	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1078		1280
1079	Sync the data portion of the file specified by C<$offset> and C<$length>	1281	Sync the data portion of the file specified by C<$offset> and C<$length>
1080	to disk (but NOT the metadata), by calling the Linux-specific	1282	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1084	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1286	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1085	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1287	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1086	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1288	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1087	manpage for details.	1289	manpage for details.
1088		1290
1089	=item aio_pathsync $path, $callback->($status)	1291	=item aio_pathsync $pathname, $callback->($status)
1090		1292
1091	This request tries to open, fsync and close the given path. This is a	1293	This request tries to open, fsync and close the given path. This is a
1092	composite request intended to sync directories after directory operations	1294	composite request intended to sync directories after directory operations
1093	(E.g. rename). This might not work on all operating systems or have any	1295	(E.g. rename). This might not work on all operating systems or have any
1094	specific effect, but usually it makes sure that directory changes get	1296	specific effect, but usually it makes sure that directory changes get
…		…
1125	};	1327	};
1126		1328
1127	$grp	1329	$grp
1128	}	1330	}
1129		1331
1130	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1332	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1131		1333
1132	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1334	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1133	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1335	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1134	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1336	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1135	scalar must only be modified in-place while an aio operation is pending on	1337	scalar must only be modified in-place while an aio operation is pending on
…		…
1137		1339
1138	It calls the C<msync> function of your OS, if available, with the memory	1340	It calls the C<msync> function of your OS, if available, with the memory
1139	area starting at C<$offset> in the string and ending C<$length> bytes	1341	area starting at C<$offset> in the string and ending C<$length> bytes
1140	later. If C<$length> is negative, counts from the end, and if C<$length>	1342	later. If C<$length> is negative, counts from the end, and if C<$length>
1141	is C<undef>, then it goes till the end of the string. The flags can be	1343	is C<undef>, then it goes till the end of the string. The flags can be
1142	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1344	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1143	C<IO::AIO::MS_SYNC>.	1345	C<IO::AIO::MS_INVALIDATE>.
1144		1346
1145	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1347	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1146		1348
1147	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1349	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1148	scalars.	1350	scalars.
1149		1351
1150	It touches (reads or writes) all memory pages in the specified	1352	It touches (reads or writes) all memory pages in the specified
1151	range inside the scalar. All caveats and parameters are the same	1353	range inside the scalar. All caveats and parameters are the same
1152	as for C<aio_msync>, above, except for flags, which must be either	1354	as for C<aio_msync>, above, except for flags, which must be either
1153	C<0> (which reads all pages and ensures they are instantiated) or	1355	C<0> (which reads all pages and ensures they are instantiated) or
1154	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1356	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1155	writing an octet from it, which dirties the page).	1357	writing an octet from it, which dirties the page).
1156		1358
1157	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1359	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1158		1360
1159	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1361	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1190	documented under L<MISCELLANEOUS FUNCTIONS>.	1392	documented under L<MISCELLANEOUS FUNCTIONS>.
1191		1393
1192	Example: asynchronously lock all current and future pages into memory.	1394	Example: asynchronously lock all current and future pages into memory.
1193		1395
1194	aio_mlockall IO::AIO::MCL_FUTURE;	1396	aio_mlockall IO::AIO::MCL_FUTURE;
		1397
		1398	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1399
		1400	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1401	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1402	the ioctl is not available on your OS, then this request will fail with
		1403	C<ENOSYS>.
		1404
		1405	C<$start> is the starting offset to query extents for, C<$length> is the
		1406	size of the range to query - if it is C<undef>, then the whole file will
		1407	be queried.
		1408
		1409	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1410	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1411	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1412	the data portion.
		1413
		1414	C<$count> is the maximum number of extent records to return. If it is
		1415	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1416	case, if it is C<0>, then the callback receives the number of extents
		1417	instead of the extents themselves (which is unreliable, see below).
		1418
		1419	If an error occurs, the callback receives no arguments. The special
		1420	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1421
		1422	Otherwise, the callback receives an array reference with extent
		1423	structures. Each extent structure is an array reference itself, with the
		1424	following members:
		1425
		1426	[$logical, $physical, $length, $flags]
		1427
		1428	Flags is any combination of the following flag values (typically either C<0>
		1429	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1430
		1431	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1432	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1433	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1434	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1435	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1436	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1437
		1438	At the time of this writing (Linux 3.2), this request is unreliable unless
		1439	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1440	it to return all extents of a range for files with a large number of
		1441	extents. The code (only) works around all these issues if C<$count> is
		1442	C<undef>.
1195		1443
1196	=item aio_group $callback->(...)	1444	=item aio_group $callback->(...)
1197		1445
1198	This is a very special aio request: Instead of doing something, it is a	1446	This is a very special aio request: Instead of doing something, it is a
1199	container for other aio requests, which is useful if you want to bundle	1447	container for other aio requests, which is useful if you want to bundle
…		…
1236	like sleep and file handle readable/writable, the overhead this creates is	1484	like sleep and file handle readable/writable, the overhead this creates is
1237	immense (it blocks a thread for a long time) so do not use this function	1485	immense (it blocks a thread for a long time) so do not use this function
1238	except to put your application under artificial I/O pressure.	1486	except to put your application under artificial I/O pressure.
1239		1487
1240	=back	1488	=back
		1489
		1490
		1491	=head2 IO::AIO::WD - multiple working directories
		1492
		1493	Your process only has one current working directory, which is used by all
		1494	threads. This makes it hard to use relative paths (some other component
		1495	could call C<chdir> at any time, and it is hard to control when the path
		1496	will be used by IO::AIO).
		1497
		1498	One solution for this is to always use absolute paths. This usually works,
		1499	but can be quite slow (the kernel has to walk the whole path on every
		1500	access), and can also be a hassle to implement.
		1501
		1502	Newer POSIX systems have a number of functions (openat, fdopendir,
		1503	futimensat and so on) that make it possible to specify working directories
		1504	per operation.
		1505
		1506	For portability, and because the clowns who "designed", or shall I write,
		1507	perpetrated this new interface were obviously half-drunk, this abstraction
		1508	cannot be perfect, though.
		1509
		1510	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1511	object. This object stores the canonicalised, absolute version of the
		1512	path, and on systems that allow it, also a directory file descriptor.
		1513
		1514	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1515	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1516	object and a pathname instead (or the IO::AIO::WD object alone, which
		1517	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1518	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1519	to that IO::AIO::WD object.
		1520
		1521	For example, to get a wd object for F</etc> and then stat F<passwd>
		1522	inside, you would write:
		1523
		1524	aio_wd "/etc", sub {
		1525	my $etcdir = shift;
		1526
		1527	# although $etcdir can be undef on error, there is generally no reason
		1528	# to check for errors here, as aio_stat will fail with ENOENT
		1529	# when $etcdir is undef.
		1530
		1531	aio_stat [$etcdir, "passwd"], sub {
		1532	# yay
		1533	};
		1534	};
		1535
		1536	The fact that C<aio_wd> is a request and not a normal function shows that
		1537	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1538	which is why it is done asynchronously.
		1539
		1540	To stat the directory obtained with C<aio_wd> above, one could write
		1541	either of the following three request calls:
		1542
		1543	aio_lstat "/etc" , sub { ... # pathname as normal string
		1544	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1545	aio_lstat $wd , sub { ... # shorthand for the previous
		1546
		1547	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1548	object and the pathname string, so you could write the following without
		1549	causing any issues due to C<$path> getting reused:
		1550
		1551	my $path = [$wd, undef];
		1552
		1553	for my $name (qw(abc def ghi)) {
		1554	$path->[1] = $name;
		1555	aio_stat $path, sub {
		1556	# ...
		1557	};
		1558	}
		1559
		1560	There are some caveats: when directories get renamed (or deleted), the
		1561	pathname string doesn't change, so will point to the new directory (or
		1562	nowhere at all), while the directory fd, if available on the system,
		1563	will still point to the original directory. Most functions accepting a
		1564	pathname will use the directory fd on newer systems, and the string on
		1565	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1566	the string form of the pathname.
		1567
		1568	So this functionality is mainly useful to get some protection against
		1569	C<chdir>, to easily get an absolute path out of a relative path for future
		1570	reference, and to speed up doing many operations in the same directory
		1571	(e.g. when stat'ing all files in a directory).
		1572
		1573	The following functions implement this working directory abstraction:
		1574
		1575	=over 4
		1576
		1577	=item aio_wd $pathname, $callback->($wd)
		1578
		1579	Asynchonously canonicalise the given pathname and convert it to an
		1580	IO::AIO::WD object representing it. If possible and supported on the
		1581	system, also open a directory fd to speed up pathname resolution relative
		1582	to this working directory.
		1583
		1584	If something goes wrong, then C<undef> is passwd to the callback instead
		1585	of a working directory object and C<$!> is set appropriately. Since
		1586	passing C<undef> as working directory component of a pathname fails the
		1587	request with C<ENOENT>, there is often no need for error checking in the
		1588	C<aio_wd> callback, as future requests using the value will fail in the
		1589	expected way.
		1590
		1591	=item IO::AIO::CWD
		1592
		1593	This is a compiletime constant (object) that represents the process
		1594	current working directory.
		1595
		1596	Specifying this object as working directory object for a pathname is as if
		1597	the pathname would be specified directly, without a directory object. For
		1598	example, these calls are functionally identical:
		1599
		1600	aio_stat "somefile", sub { ... };
		1601	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1602
		1603	=back
		1604
		1605	To recover the path associated with an IO::AIO::WD object, you can use
		1606	C<aio_realpath>:
		1607
		1608	aio_realpath $wd, sub {
		1609	warn "path is $_[0]\n";
		1610	};
		1611
		1612	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1613	sometimes, fall back to using an absolue path.
1241		1614
1242	=head2 IO::AIO::REQ CLASS	1615	=head2 IO::AIO::REQ CLASS
1243		1616
1244	All non-aggregate C<aio_*> functions return an object of this class when	1617	All non-aggregate C<aio_*> functions return an object of this class when
1245	called in non-void context.	1618	called in non-void context.
…		…
1363		1736
1364	Sets a feeder/generator on this group: every group can have an attached	1737	Sets a feeder/generator on this group: every group can have an attached
1365	generator that generates requests if idle. The idea behind this is that,	1738	generator that generates requests if idle. The idea behind this is that,
1366	although you could just queue as many requests as you want in a group,	1739	although you could just queue as many requests as you want in a group,
1367	this might starve other requests for a potentially long time. For example,	1740	this might starve other requests for a potentially long time. For example,
1368	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1741	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1369	delaying any later requests for a long time.	1742	requests, delaying any later requests for a long time.
1370		1743
1371	To avoid this, and allow incremental generation of requests, you can	1744	To avoid this, and allow incremental generation of requests, you can
1372	instead a group and set a feeder on it that generates those requests. The	1745	instead a group and set a feeder on it that generates those requests. The
1373	feed callback will be called whenever there are few enough (see C<limit>,	1746	feed callback will be called whenever there are few enough (see C<limit>,
1374	below) requests active in the group itself and is expected to queue more	1747	below) requests active in the group itself and is expected to queue more
…		…
1423		1796
1424	See C<poll_cb> for an example.	1797	See C<poll_cb> for an example.
1425		1798
1426	=item IO::AIO::poll_cb	1799	=item IO::AIO::poll_cb
1427		1800
1428	Process some outstanding events on the result pipe. You have to call	1801	Process some requests that have reached the result phase (i.e. they have
		1802	been executed but the results are not yet reported). You have to call
		1803	this "regularly" to finish outstanding requests.
		1804
1429	this regularly. Returns C<0> if all events could be processed (or there	1805	Returns C<0> if all events could be processed (or there were no
1430	were no events to process), or C<-1> if it returned earlier for whatever	1806	events to process), or C<-1> if it returned earlier for whatever
1431	reason. Returns immediately when no events are outstanding. The amount of	1807	reason. Returns immediately when no events are outstanding. The amount
1432	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1808	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1433	C<IO::AIO::max_poll_time>.	1809	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1434		1810
1435	If not all requests were processed for whatever reason, the filehandle	1811	If not all requests were processed for whatever reason, the poll file
1436	will still be ready when C<poll_cb> returns, so normally you don't have to	1812	descriptor will still be ready when C<poll_cb> returns, so normally you
1437	do anything special to have it called later.	1813	don't have to do anything special to have it called later.
1438		1814
1439	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1815	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1440	ready, it can be beneficial to call this function from loops which submit	1816	ready, it can be beneficial to call this function from loops which submit
1441	a lot of requests, to make sure the results get processed when they become	1817	a lot of requests, to make sure the results get processed when they become
1442	available and not just when the loop is finished and the event loop takes	1818	available and not just when the loop is finished and the event loop takes
…		…
1451	poll => 'r', async => 1,	1827	poll => 'r', async => 1,
1452	cb => \&IO::AIO::poll_cb);	1828	cb => \&IO::AIO::poll_cb);
1453		1829
1454	=item IO::AIO::poll_wait	1830	=item IO::AIO::poll_wait
1455		1831
1456	If there are any outstanding requests and none of them in the result	1832	Wait until either at least one request is in the result phase or no
1457	phase, wait till the result filehandle becomes ready for reading (simply	1833	requests are outstanding anymore.
1458	does a C<select> on the filehandle. This is useful if you want to	1834
1459	synchronously wait for some requests to finish).	1835	This is useful if you want to synchronously wait for some requests to
		1836	become ready, without actually handling them.
1460		1837
1461	See C<nreqs> for an example.	1838	See C<nreqs> for an example.
1462		1839
1463	=item IO::AIO::poll	1840	=item IO::AIO::poll
1464		1841
…		…
1585		1962
1586	This is a very bad function to use in interactive programs because it	1963	This is a very bad function to use in interactive programs because it
1587	blocks, and a bad way to reduce concurrency because it is inexact: Better	1964	blocks, and a bad way to reduce concurrency because it is inexact: Better
1588	use an C<aio_group> together with a feed callback.	1965	use an C<aio_group> together with a feed callback.
1589		1966
1590	It's main use is in scripts without an event loop - when you want to stat	1967	Its main use is in scripts without an event loop - when you want to stat
1591	a lot of files, you can write somehting like this:	1968	a lot of files, you can write something like this:
1592		1969
1593	IO::AIO::max_outstanding 32;	1970	IO::AIO::max_outstanding 32;
1594		1971
1595	for my $path (...) {	1972	for my $path (...) {
1596	aio_stat $path , ...;	1973	aio_stat $path , ...;
…		…
1635		2012
1636	=back	2013	=back
1637		2014
1638	=head3 MISCELLANEOUS FUNCTIONS	2015	=head3 MISCELLANEOUS FUNCTIONS
1639		2016
1640	IO::AIO implements some functions that might be useful, but are not	2017	IO::AIO implements some functions that are useful when you want to use
1641	asynchronous.	2018	some "Advanced I/O" function not available to in Perl, without going the
		2019	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2020	counterpart.
1642		2021
1643	=over 4	2022	=over 4
		2023
		2024	=item $numfd = IO::AIO::get_fdlimit
		2025
		2026	This function is I<EXPERIMENTAL> and subject to change.
		2027
		2028	Tries to find the current file descriptor limit and returns it, or
		2029	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2030	the highest valid file descriptor number.
		2031
		2032	=item IO::AIO::min_fdlimit [$numfd]
		2033
		2034	This function is I<EXPERIMENTAL> and subject to change.
		2035
		2036	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2037	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2038	is missing, it will try to set a very high limit, although this is not
		2039	recommended when you know the actual minimum that you require.
		2040
		2041	If the limit cannot be raised enough, the function makes a best-effort
		2042	attempt to increase the limit as much as possible, using various
		2043	tricks, while still failing. You can query the resulting limit using
		2044	C<IO::AIO::get_fdlimit>.
		2045
		2046	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2047	true.
1644		2048
1645	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2049	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1646		2050
1647	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2051	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1648	but is blocking (this makes most sense if you know the input data is	2052	but is blocking (this makes most sense if you know the input data is
…		…
1653		2057
1654	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2058	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1655		2059
1656	Simply calls the C<posix_fadvise> function (see its	2060	Simply calls the C<posix_fadvise> function (see its
1657	manpage for details). The following advice constants are	2061	manpage for details). The following advice constants are
1658	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2062	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1659	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2063	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1660	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2064	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1661		2065
1662	On systems that do not implement C<posix_fadvise>, this function returns	2066	On systems that do not implement C<posix_fadvise>, this function returns
1663	ENOSYS, otherwise the return value of C<posix_fadvise>.	2067	ENOSYS, otherwise the return value of C<posix_fadvise>.
1664		2068
1665	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2069	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1666		2070
1667	Simply calls the C<posix_madvise> function (see its	2071	Simply calls the C<posix_madvise> function (see its
1668	manpage for details). The following advice constants are	2072	manpage for details). The following advice constants are
1669	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2073	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1670	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2074	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2075	C<IO::AIO::MADV_DONTNEED>.
		2076
		2077	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2078	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2079	will be reduced to fit into the C<$scalar>.
1671		2080
1672	On systems that do not implement C<posix_madvise>, this function returns	2081	On systems that do not implement C<posix_madvise>, this function returns
1673	ENOSYS, otherwise the return value of C<posix_madvise>.	2082	ENOSYS, otherwise the return value of C<posix_madvise>.
1674		2083
1675	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2084	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1676		2085
1677	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2086	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1678	$scalar (see its manpage for details). The following protect	2087	$scalar (see its manpage for details). The following protect
1679	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2088	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1680	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2089	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2090
		2091	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2092	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2093	will be reduced to fit into the C<$scalar>.
1681		2094
1682	On systems that do not implement C<mprotect>, this function returns	2095	On systems that do not implement C<mprotect>, this function returns
1683	ENOSYS, otherwise the return value of C<mprotect>.	2096	ENOSYS, otherwise the return value of C<mprotect>.
1684		2097
1685	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2098	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1686		2099
1687	Memory-maps a file (or anonymous memory range) and attaches it to the	2100	Memory-maps a file (or anonymous memory range) and attaches it to the
1688	given C<$scalar>, which will act like a string scalar.	2101	given C<$scalar>, which will act like a string scalar. Returns true on
		2102	success, and false otherwise.
1689		2103
		2104	The scalar must exist, but its contents do not matter - this means you
		2105	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2106	the scalar first.
		2107
1690	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2108	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1691	change the string length, and most read-only operations such as copying it	2109	which don't change the string length, and most read-only operations such
1692	or searching it with regexes and so on.	2110	as copying it or searching it with regexes and so on.
1693		2111
1694	Anything else is unsafe and will, at best, result in memory leaks.	2112	Anything else is unsafe and will, at best, result in memory leaks.
1695		2113
1696	The memory map associated with the C<$scalar> is automatically removed	2114	The memory map associated with the C<$scalar> is automatically removed
1697	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2115	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1698	C<IO::AIO::munmap> functions are called.	2116	or C<IO::AIO::munmap> functions are called on it.
1699		2117
1700	This calls the C<mmap>(2) function internally. See your system's manual	2118	This calls the C<mmap>(2) function internally. See your system's manual
1701	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2119	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1702		2120
1703	The C<$length> must be larger than zero and smaller than the actual	2121	The C<$length> must be larger than zero and smaller than the actual
1704	filesize.	2122	filesize.
1705		2123
1706	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2124	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1707	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2125	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1708		2126
1709	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2127	C<$flags> can be a combination of
1710	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2128	C<IO::AIO::MAP_SHARED> or
1711	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2129	C<IO::AIO::MAP_PRIVATE>,
		2130	or a number of system-specific flags (when not available, the are C<0>):
1712	(which is set to C<MAP_ANON> if your system only provides this	2131	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1713	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2132	C<IO::AIO::MAP_LOCKED>,
1714	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2133	C<IO::AIO::MAP_NORESERVE>,
		2134	C<IO::AIO::MAP_POPULATE>,
1715	C<IO::AIO::MAP_NONBLOCK>	2135	C<IO::AIO::MAP_NONBLOCK>,
		2136	C<IO::AIO::MAP_FIXED>,
		2137	C<IO::AIO::MAP_GROWSDOWN>,
		2138	C<IO::AIO::MAP_32BIT>,
		2139	C<IO::AIO::MAP_HUGETLB> or
		2140	C<IO::AIO::MAP_STACK>.
1716		2141
1717	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2142	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1718		2143
1719	C<$offset> is the offset from the start of the file - it generally must be	2144	C<$offset> is the offset from the start of the file - it generally must be
1720	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2145	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1734		2159
1735	=item IO::AIO::munmap $scalar	2160	=item IO::AIO::munmap $scalar
1736		2161
1737	Removes a previous mmap and undefines the C<$scalar>.	2162	Removes a previous mmap and undefines the C<$scalar>.
1738		2163
		2164	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2165
		2166	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2167	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2168	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2169
		2170	Returns true if successful, and false otherwise. If the underlying mmapped
		2171	region has changed address, then the true value has the numerical value
		2172	C<1>, otherwise it has the numerical value C<0>:
		2173
		2174	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2175	or die "mremap: $!";
		2176
		2177	if ($success*1) {
		2178	warn "scalar has chanegd address in memory\n";
		2179	}
		2180
		2181	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2182	implemented, but not supported and might go away in a future version.
		2183
		2184	On systems where this call is not supported or is not emulated, this call
		2185	returns falls and sets C<$!> to C<ENOSYS>.
		2186
1739	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2187	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1740		2188
1741	Calls the C<munlock> function, undoing the effects of a previous	2189	Calls the C<munlock> function, undoing the effects of a previous
1742	C<aio_mlock> call (see its description for details).	2190	C<aio_mlock> call (see its description for details).
1743		2191
…		…
1745		2193
1746	Calls the C<munlockall> function.	2194	Calls the C<munlockall> function.
1747		2195
1748	On systems that do not implement C<munlockall>, this function returns	2196	On systems that do not implement C<munlockall>, this function returns
1749	ENOSYS, otherwise the return value of C<munlockall>.	2197	ENOSYS, otherwise the return value of C<munlockall>.
		2198
		2199	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2200
		2201	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2202	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2203	should be the file offset.
		2204
		2205	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2206	silently corrupt the data in this case.
		2207
		2208	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2209	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2210	C<IO::AIO::SPLICE_F_GIFT>.
		2211
		2212	See the C<splice(2)> manpage for details.
		2213
		2214	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2215
		2216	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2217	description for C<IO::AIO::splice> above for details.
		2218
		2219	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2220
		2221	Attempts to query or change the pipe buffer size. Obviously works only
		2222	on pipes, and currently works only on GNU/Linux systems, and fails with
		2223	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2224	size on other systems, drop me a note.
		2225
		2226	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2227
		2228	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2229	C<$flags> is missing or C<0>, then this should be the same as a call to
		2230	perl's built-in C<pipe> function and create a new pipe, and works on
		2231	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2232	(..., 4096, O_BINARY)>.
		2233
		2234	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2235	the given flags (Linux 2.6.27, glibc 2.9).
		2236
		2237	On success, the read and write file handles are returned.
		2238
		2239	On error, nothing will be returned. If the pipe2 syscall is missing and
		2240	C<$flags> is non-zero, fails with C<ENOSYS>.
		2241
		2242	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2243	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2244	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2245
		2246	Example: create a pipe race-free w.r.t. threads and fork:
		2247
		2248	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2249	or die "pipe2: $!\n";
		2250
		2251	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2252
		2253	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2254	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2255
		2256	On success, the new eventfd filehandle is returned, otherwise returns
		2257	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2258
		2259	Please refer to L<eventfd(2)> for more info on this call.
		2260
		2261	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2262	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2263
		2264	Example: create a new eventfd filehandle:
		2265
		2266	$fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC
		2267	or die "eventfd: $!\n";
		2268
		2269	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2270
		2271	This is a direct interface to the Linux L<timerfd_create(2)> system call. The
		2272	(unhelpful) default for C<$flags> is C<0>.
		2273
		2274	On success, the new timerfd filehandle is returned, otherwise returns
		2275	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2276
		2277	Please refer to L<timerfd_create(2)> for more info on this call.
		2278
		2279	The following C<$clockid> values are
		2280	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2281	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2282	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2283	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2284
		2285	The following C<$flags> values are available (Linux
		2286	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2287
		2288	Example: create a new timerfd and set it to one-second repeated alarms,
		2289	then wait for two alarms:
		2290
		2291	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2292	or die "timerfd_create: $!\n";
		2293
		2294	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2295	or die "timerfd_settime: $!\n";
		2296
		2297	for (1..2) {
		2298	8 == sysread $fh, my $buf, 8
		2299	or die "timerfd read failure\n";
		2300
		2301	printf "number of expirations (likely 1): %d\n",
		2302	unpack "Q", $buf;
		2303	}
		2304
		2305	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2306
		2307	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2308	call. Please refer to its manpage for more info on this call.
		2309
		2310	The new itimerspec is specified using two (possibly fractional) second
		2311	values, C<$new_interval> and C<$new_value>).
		2312
		2313	On success, the current interval and value are returned (as per
		2314	C<timerfd_gettime>). On failure, the empty list is returned.
		2315
		2316	The following C<$flags> values are
		2317	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2318	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2319
		2320	See C<IO::AIO::timerfd_create> for a full example.
		2321
		2322	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2323
		2324	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2325	call. Please refer to its manpage for more info on this call.
		2326
		2327	On success, returns the current values of interval and value for the given
		2328	timerfd (as potentially fractional second values). On failure, the empty
		2329	list is returned.
1750		2330
1751	=back	2331	=back
1752		2332
1753	=cut	2333	=cut
1754		2334
…		…
1792	=head2 FORK BEHAVIOUR	2372	=head2 FORK BEHAVIOUR
1793		2373
1794	Usage of pthreads in a program changes the semantics of fork	2374	Usage of pthreads in a program changes the semantics of fork
1795	considerably. Specifically, only async-safe functions can be called after	2375	considerably. Specifically, only async-safe functions can be called after
1796	fork. Perl doesn't know about this, so in general, you cannot call fork	2376	fork. Perl doesn't know about this, so in general, you cannot call fork
1797	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,	2377	with defined behaviour in perl if pthreads are involved. IO::AIO uses
1798	but many other extensions and (for inexplicable reasons) perl itself often	2378	pthreads, so this applies, but many other extensions and (for inexplicable
1799	is linked against pthreads, so this limitation applies.	2379	reasons) perl itself often is linked against pthreads, so this limitation
		2380	applies to quite a lot of perls.
1800		2381
1801	Some operating systems have extensions that allow safe use of fork, and	2382	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1802	this module should do "the right thing" on those, and tries on others. At	2383	only works in the process that loaded it. Forking is fully supported, but
1803	the time of this writing (2011) only GNU/Linux supports these extensions	2384	using IO::AIO in the child is not.
1804	to POSIX.	2385
		2386	You might get around by not I<using> IO::AIO before (or after)
		2387	forking. You could also try to call the L<IO::AIO::reinit> function in the
		2388	child:
		2389
		2390	=over 4
		2391
		2392	=item IO::AIO::reinit
		2393
		2394	Abandons all current requests and I/O threads and simply reinitialises all
		2395	data structures. This is not an operation supported by any standards, but
		2396	happens to work on GNU/Linux and some newer BSD systems.
		2397
		2398	The only reasonable use for this function is to call it after forking, if
		2399	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2400	the process will result in undefined behaviour. Calling it at any time
		2401	will also result in any undefined (by POSIX) behaviour.
		2402
		2403	=back
		2404
		2405	=head2 LINUX-SPECIFIC CALLS
		2406
		2407	When a call is documented as "linux-specific" then this means it
		2408	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2409	availability and compatibility of such calls regardless of the platform
		2410	it is compiled on, so platforms such as FreeBSD which often implement
		2411	these calls will work. When in doubt, call them and see if they fail wth
		2412	C<ENOSYS>.
1805		2413
1806	=head2 MEMORY USAGE	2414	=head2 MEMORY USAGE
1807		2415
1808	Per-request usage:	2416	Per-request usage:
1809		2417
…		…
1822	temporary buffers, and each thread requires a stack and other data	2430	temporary buffers, and each thread requires a stack and other data
1823	structures (usually around 16k-128k, depending on the OS).	2431	structures (usually around 16k-128k, depending on the OS).
1824		2432
1825	=head1 KNOWN BUGS	2433	=head1 KNOWN BUGS
1826		2434
1827	Known bugs will be fixed in the next release.	2435	Known bugs will be fixed in the next release :)
		2436
		2437	=head1 KNOWN ISSUES
		2438
		2439	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2440	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2441	non-created hash slots or other scalars I didn't think of. It's best to
		2442	avoid such and either use scalar variables or making sure that the scalar
		2443	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2444
		2445	I am not sure anything can be done about this, so this is considered a
		2446	known issue, rather than a bug.
1828		2447
1829	=head1 SEE ALSO	2448	=head1 SEE ALSO
1830		2449
1831	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2450	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1832	more natural syntax.	2451	more natural syntax.

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