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Revision 1.195 by root, Fri May 27 19:56:31 2011 UTC vs.
Revision 1.292 by root, Tue Aug 14 09:29:50 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 = '3.9';	176	our $VERSION = 4.53;
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
…		…
436		486
437	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	487	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
438	reading at byte offset C<$in_offset>, and starts writing at the current	488	reading at byte offset C<$in_offset>, and starts writing at the current
439	file offset of C<$out_fh>. Because of that, it is not safe to issue more	489	file offset of C<$out_fh>. Because of that, it is not safe to issue more
440	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	490	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
441	other.	491	other. The same C<$in_fh> works fine though, as this function does not
		492	move or use the file offset of C<$in_fh>.
442		493
443	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than	494	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
444	are written, and there is no way to find out how many bytes have been read	495	are written, and there is no way to find out how many more bytes have been
445	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of	496	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
446	bytes written to C<$out_fh>. Only if the result value equals C<$length>	497	number of bytes written to C<$out_fh>. Only if the result value equals
447	one can assume that C<$length> bytes have been read.	498	C<$length> one can assume that C<$length> bytes have been read.
448		499
449	Unlike with other C<aio_> functions, it makes a lot of sense to use	500	Unlike with other C<aio_> functions, it makes a lot of sense to use
450	C<aio_sendfile> on non-blocking sockets, as long as one end (typically	501	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
451	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while	502	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
452	the socket I/O will be non-blocking. Note, however, that you can run into	503	the socket I/O will be non-blocking. Note, however, that you can run
453	a trap where C<aio_sendfile> reads some data with readahead, then fails	504	into a trap where C<aio_sendfile> reads some data with readahead, then
454	to write all data, and when the socket is ready the next time, the data	505	fails to write all data, and when the socket is ready the next time, the
455	in the cache is already lost, forcing C<aio_sendfile> to again hit the	506	data in the cache is already lost, forcing C<aio_sendfile> to again hit
456	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage	507	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
457	much better.	508	resource usage.
458		509
459	This call tries to make use of a native C<sendfile> syscall to provide	510	This call tries to make use of a native C<sendfile>-like syscall to
460	zero-copy operation. For this to work, C<$out_fh> should refer to a	511	provide zero-copy operation. For this to work, C<$out_fh> should refer to
461	socket, and C<$in_fh> should refer to an mmap'able file.	512	a socket, and C<$in_fh> should refer to an mmap'able file.
462		513
463	If a native sendfile cannot be found or it fails with C<ENOSYS>,	514	If a native sendfile cannot be found or it fails with C<ENOSYS>,
464	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	515	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
465	it will be emulated, so you can call C<aio_sendfile> on any type of	516	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
466	filehandle regardless of the limitations of the operating system.	517	type of filehandle regardless of the limitations of the operating system.
		518
		519	As native sendfile syscalls (as practically any non-POSIX interface hacked
		520	together in a hurry to improve benchmark numbers) tend to be rather buggy
		521	on many systems, this implementation tries to work around some known bugs
		522	in Linux and FreeBSD kernels (probably others, too), but that might fail,
		523	so you really really should check the return value of C<aio_sendfile> -
		524	fewer bytes than expected might have been transferred.
467		525
468		526
469	=item aio_readahead $fh,$offset,$length, $callback->($retval)	527	=item aio_readahead $fh,$offset,$length, $callback->($retval)
470		528
471	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
…		…
475	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
476	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
477	(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
478	file. The current file offset of the file is left unchanged.	536	file. The current file offset of the file is left unchanged.
479		537
480	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
481	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.
482		540
483		541
484	=item aio_stat $fh_or_path, $callback->($status)	542	=item aio_stat $fh_or_path, $callback->($status)
485		543
486	=item aio_lstat $fh, $callback->($status)	544	=item aio_lstat $fh, $callback->($status)
…		…
502	behaviour).	560	behaviour).
503		561
504	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	562	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
505	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	563	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
506	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	564	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		565
		566	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		567	ACCESS>.
507		568
508	Example: Print the length of F</etc/passwd>:	569	Example: Print the length of F</etc/passwd>:
509		570
510	aio_stat "/etc/passwd", sub {	571	aio_stat "/etc/passwd", sub {
511	$_[0] and die "stat failed: $!";	572	$_[0] and die "stat failed: $!";
…		…
555	namemax => 255,	616	namemax => 255,
556	frsize => 1024,	617	frsize => 1024,
557	fsid => 1810	618	fsid => 1810
558	}	619	}
559		620
560
561	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	621	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
562		622
563	Works like perl's C<utime> function (including the special case of $atime	623	Works like perl's C<utime> function (including the special case of $atime
564	and $mtime being undef). Fractional times are supported if the underlying	624	and $mtime being undef). Fractional times are supported if the underlying
565	syscalls support them.	625	syscalls support them.
…		…
592	=item aio_truncate $fh_or_path, $offset, $callback->($status)	652	=item aio_truncate $fh_or_path, $offset, $callback->($status)
593		653
594	Works like truncate(2) or ftruncate(2).	654	Works like truncate(2) or ftruncate(2).
595		655
596		656
		657	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		658
		659	Allocates or frees disk space according to the C<$mode> argument. See the
		660	linux C<fallocate> documentation for details.
		661
		662	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		663	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		664	to deallocate a file range.
		665
		666	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		667	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		668	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		669	to unshare shared blocks (see your L<fallocate(2)> manpage).
		670
		671	The file system block size used by C<fallocate> is presumably the
		672	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		673	can dictate other limitations.
		674
		675	If C<fallocate> isn't available or cannot be emulated (currently no
		676	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		677
		678
597	=item aio_chmod $fh_or_path, $mode, $callback->($status)	679	=item aio_chmod $fh_or_path, $mode, $callback->($status)
598		680
599	Works like perl's C<chmod> function.	681	Works like perl's C<chmod> function.
600		682
601		683
…		…
603		685
604	Asynchronously unlink (delete) a file and call the callback with the	686	Asynchronously unlink (delete) a file and call the callback with the
605	result code.	687	result code.
606		688
607		689
608	=item aio_mknod $path, $mode, $dev, $callback->($status)	690	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
609		691
610	[EXPERIMENTAL]	692	[EXPERIMENTAL]
611		693
612	Asynchronously create a device node (or fifo). See mknod(2).	694	Asynchronously create a device node (or fifo). See mknod(2).
613		695
614	The only (POSIX-) portable way of calling this function is:	696	The only (POSIX-) portable way of calling this function is:
615		697
616	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	698	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
617		699
618	See C<aio_stat> for info about some potentially helpful extra constants	700	See C<aio_stat> for info about some potentially helpful extra constants
619	and functions.	701	and functions.
620		702
621	=item aio_link $srcpath, $dstpath, $callback->($status)	703	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
628		710
629	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	711	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
630	the path C<$dstpath> and call the callback with the result code.	712	the path C<$dstpath> and call the callback with the result code.
631		713
632		714
633	=item aio_readlink $path, $callback->($link)	715	=item aio_readlink $pathname, $callback->($link)
634		716
635	Asynchronously read the symlink specified by C<$path> and pass it to	717	Asynchronously read the symlink specified by C<$path> and pass it to
636	the callback. If an error occurs, nothing or undef gets passed to the	718	the callback. If an error occurs, nothing or undef gets passed to the
637	callback.	719	callback.
638		720
639		721
		722	=item aio_realpath $pathname, $callback->($path)
		723
		724	Asynchronously make the path absolute and resolve any symlinks in
		725	C<$path>. The resulting path only consists of directories (same as
		726	L<Cwd::realpath>).
		727
		728	This request can be used to get the absolute path of the current working
		729	directory by passing it a path of F<.> (a single dot).
		730
		731
640	=item aio_rename $srcpath, $dstpath, $callback->($status)	732	=item aio_rename $srcpath, $dstpath, $callback->($status)
641		733
642	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	734	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
643	rename(2) and call the callback with the result code.	735	rename(2) and call the callback with the result code.
		736
		737	On systems that support the AIO::WD working directory abstraction
		738	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		739	of failing, C<rename> is called on the absolute path of C<$wd>.
		740
		741
		742	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		743
		744	Basically a version of C<aio_rename> with an additional C<$flags>
		745	argument. Calling this with C<$flags=0> is the same as calling
		746	C<aio_rename>.
		747
		748	Non-zero flags are currently only supported on GNU/Linux systems that
		749	support renameat2. Other systems fail with C<ENOSYS> in this case.
		750
		751	The following constants are available (missing ones are, as usual C<0>),
		752	see renameat2(2) for details:
		753
		754	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		755	and C<IO::AIO::RENAME_WHITEOUT>.
644		756
645		757
646	=item aio_mkdir $pathname, $mode, $callback->($status)	758	=item aio_mkdir $pathname, $mode, $callback->($status)
647		759
648	Asynchronously mkdir (create) a directory and call the callback with	760	Asynchronously mkdir (create) a directory and call the callback with
…		…
653	=item aio_rmdir $pathname, $callback->($status)	765	=item aio_rmdir $pathname, $callback->($status)
654		766
655	Asynchronously rmdir (delete) a directory and call the callback with the	767	Asynchronously rmdir (delete) a directory and call the callback with the
656	result code.	768	result code.
657		769
		770	On systems that support the AIO::WD working directory abstraction
		771	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		772	C<rmdir> is called on the absolute path of C<$wd>.
		773
658		774
659	=item aio_readdir $pathname, $callback->($entries)	775	=item aio_readdir $pathname, $callback->($entries)
660		776
661	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	777	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
662	directory (i.e. opendir + readdir + closedir). The entries will not be	778	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
666	array-ref with the filenames.	782	array-ref with the filenames.
667		783
668		784
669	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	785	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
670		786
671	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	787	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
672	behaviour and output format. In case of an error, C<$entries> will be	788	tune behaviour and output format. In case of an error, C<$entries> will be
673	C<undef>.	789	C<undef>.
674		790
675	The flags are a combination of the following constants, ORed together (the	791	The flags are a combination of the following constants, ORed together (the
676	flags will also be passed to the callback, possibly modified):	792	flags will also be passed to the callback, possibly modified):
677		793
678	=over 4	794	=over 4
679		795
680	=item IO::AIO::READDIR_DENTS	796	=item IO::AIO::READDIR_DENTS
681		797
682	When this flag is off, then the callback gets an arrayref consisting of	798	Normally the callback gets an arrayref consisting of names only (as
683	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	799	with C<aio_readdir>). If this flag is set, then the callback gets an
684	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	800	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
685	entry in more detail.	801	single directory entry in more detail:
686		802
687	C<$name> is the name of the entry.	803	C<$name> is the name of the entry.
688		804
689	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	805	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
690		806
691	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	807	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
692	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	808	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
693	C<IO::AIO::DT_WHT>.	809	C<IO::AIO::DT_WHT>.
694		810
695	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	811	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
696	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	812	to know, you have to run stat yourself. Also, for speed/memory reasons,
697	scalars are read-only: you can not modify them.	813	the C<$type> scalars are read-only: you must not modify them.
698		814
699	C<$inode> is the inode number (which might not be exact on systems with 64	815	C<$inode> is the inode number (which might not be exact on systems with 64
700	bit inode numbers and 32 bit perls). This field has unspecified content on	816	bit inode numbers and 32 bit perls). This field has unspecified content on
701	systems that do not deliver the inode information.	817	systems that do not deliver the inode information.
702		818
…		…
713	short names are tried first.	829	short names are tried first.
714		830
715	=item IO::AIO::READDIR_STAT_ORDER	831	=item IO::AIO::READDIR_STAT_ORDER
716		832
717	When this flag is set, then the names will be returned in an order	833	When this flag is set, then the names will be returned in an order
718	suitable for stat()'ing each one. That is, when you plan to stat()	834	suitable for stat()'ing each one. That is, when you plan to stat() most or
719	all files in the given directory, then the returned order will likely	835	all files in the given directory, then the returned order will likely be
720	be fastest.	836	faster.
721		837
722	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	838	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
723	the likely dirs come first, resulting in a less optimal stat order.	839	then the likely dirs come first, resulting in a less optimal stat order
		840	for stat'ing all entries, but likely a more optimal order for finding
		841	subdirectories.
724		842
725	=item IO::AIO::READDIR_FOUND_UNKNOWN	843	=item IO::AIO::READDIR_FOUND_UNKNOWN
726		844
727	This flag should not be set when calling C<aio_readdirx>. Instead, it	845	This flag should not be set when calling C<aio_readdirx>. Instead, it
728	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	846	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
729	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	847	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
730	C<$type>'s are known, which can be used to speed up some algorithms.	848	C<$type>'s are known, which can be used to speed up some algorithms.
731		849
732	=back	850	=back
733		851
734		852
		853	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		854
		855	Opens, reads and closes the given file. The data is put into C<$data>,
		856	which is resized as required.
		857
		858	If C<$offset> is negative, then it is counted from the end of the file.
		859
		860	If C<$length> is zero, then the remaining length of the file is
		861	used. Also, in this case, the same limitations to modifying C<$data> apply
		862	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		863	with C<substr>. If the size of the file is known, specifying a non-zero
		864	C<$length> results in a performance advantage.
		865
		866	This request is similar to the older C<aio_load> request, but since it is
		867	a single request, it might be more efficient to use.
		868
		869	Example: load F</etc/passwd> into C<$passwd>.
		870
		871	my $passwd;
		872	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		873	$_[0] >= 0
		874	or die "/etc/passwd: $!\n";
		875
		876	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		877	print $passwd;
		878	};
		879	IO::AIO::flush;
		880
		881
735	=item aio_load $path, $data, $callback->($status)	882	=item aio_load $pathname, $data, $callback->($status)
736		883
737	This is a composite request that tries to fully load the given file into	884	This is a composite request that tries to fully load the given file into
738	memory. Status is the same as with aio_read.	885	memory. Status is the same as with aio_read.
		886
		887	Using C<aio_slurp> might be more efficient, as it is a single request.
739		888
740	=cut	889	=cut
741		890
742	sub aio_load($$;$) {	891	sub aio_load($$;$) {
743	my ($path, undef, $cb) = @_;	892	my ($path, undef, $cb) = @_;
…		…
763	=item aio_copy $srcpath, $dstpath, $callback->($status)	912	=item aio_copy $srcpath, $dstpath, $callback->($status)
764		913
765	Try to copy the I<file> (directories not supported as either source or	914	Try to copy the I<file> (directories not supported as either source or
766	destination) from C<$srcpath> to C<$dstpath> and call the callback with	915	destination) from C<$srcpath> to C<$dstpath> and call the callback with
767	a status of C<0> (ok) or C<-1> (error, see C<$!>).	916	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		917
		918	Existing destination files will be truncated.
768		919
769	This is a composite request that creates the destination file with	920	This is a composite request that creates the destination file with
770	mode 0200 and copies the contents of the source file into it using	921	mode 0200 and copies the contents of the source file into it using
771	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	922	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
772	uid/gid, in that order.	923	uid/gid, in that order.
…		…
862	if ($_[0] && $! == EXDEV) {	1013	if ($_[0] && $! == EXDEV) {
863	aioreq_pri $pri;	1014	aioreq_pri $pri;
864	add $grp aio_copy $src, $dst, sub {	1015	add $grp aio_copy $src, $dst, sub {
865	$grp->result ($_[0]);	1016	$grp->result ($_[0]);
866		1017
867	if (!$_[0]) {	1018	unless ($_[0]) {
868	aioreq_pri $pri;	1019	aioreq_pri $pri;
869	add $grp aio_unlink $src;	1020	add $grp aio_unlink $src;
870	}	1021	}
871	};	1022	};
872	} else {	1023	} else {
…		…
875	};	1026	};
876		1027
877	$grp	1028	$grp
878	}	1029	}
879		1030
880	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1031	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
881		1032
882	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1033	Scans a directory (similar to C<aio_readdir>) but additionally tries to
883	efficiently separate the entries of directory C<$path> into two sets of	1034	efficiently separate the entries of directory C<$path> into two sets of
884	names, directories you can recurse into (directories), and ones you cannot	1035	names, directories you can recurse into (directories), and ones you cannot
885	recurse into (everything else, including symlinks to directories).	1036	recurse into (everything else, including symlinks to directories).
886		1037
887	C<aio_scandir> is a composite request that creates of many sub requests_	1038	C<aio_scandir> is a composite request that generates many sub requests.
888	C<$maxreq> specifies the maximum number of outstanding aio requests that	1039	C<$maxreq> specifies the maximum number of outstanding aio requests that
889	this function generates. If it is C<< <= 0 >>, then a suitable default	1040	this function generates. If it is C<< <= 0 >>, then a suitable default
890	will be chosen (currently 4).	1041	will be chosen (currently 4).
891		1042
892	On error, the callback is called without arguments, otherwise it receives	1043	On error, the callback is called without arguments, otherwise it receives
…		…
916	Then entries will be sorted into likely directories a non-initial dot	1067	Then entries will be sorted into likely directories a non-initial dot
917	currently) and likely non-directories (see C<aio_readdirx>). Then every	1068	currently) and likely non-directories (see C<aio_readdirx>). Then every
918	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1069	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
919	in order of their inode numbers. If that succeeds, it assumes that the	1070	in order of their inode numbers. If that succeeds, it assumes that the
920	entry is a directory or a symlink to directory (which will be checked	1071	entry is a directory or a symlink to directory (which will be checked
921	seperately). This is often faster than stat'ing the entry itself because	1072	separately). This is often faster than stat'ing the entry itself because
922	filesystems might detect the type of the entry without reading the inode	1073	filesystems might detect the type of the entry without reading the inode
923	data (e.g. ext2fs filetype feature), even on systems that cannot return	1074	data (e.g. ext2fs filetype feature), even on systems that cannot return
924	the filetype information on readdir.	1075	the filetype information on readdir.
925		1076
926	If the known number of directories (link count - 2) has been reached, the	1077	If the known number of directories (link count - 2) has been reached, the
…		…
942		1093
943	my $grp = aio_group $cb;	1094	my $grp = aio_group $cb;
944		1095
945	$maxreq = 4 if $maxreq <= 0;	1096	$maxreq = 4 if $maxreq <= 0;
946		1097
947	# stat once	1098	# get a wd object
948	aioreq_pri $pri;	1099	aioreq_pri $pri;
949	add $grp aio_stat $path, sub {	1100	add $grp aio_wd $path, sub {
		1101	$_[0]
950	return $grp->result () if $_[0];	1102	or return $grp->result ();
951	my $now = time;
952	my $hash1 = join ":", (stat _)[0,1,3,7,9];
953		1103
954	# read the directory entries	1104	my $wd = [shift, "."];
		1105
		1106	# stat once
955	aioreq_pri $pri;	1107	aioreq_pri $pri;
956	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1108	add $grp aio_stat $wd, sub {
957	my $entries = shift
958	or return $grp->result ();	1109	return $grp->result () if $_[0];
		1110	my $now = time;
		1111	my $hash1 = join ":", (stat _)[0,1,3,7,9];
959		1112
960	# stat the dir another time	1113	# read the directory entries
961	aioreq_pri $pri;	1114	aioreq_pri $pri;
		1115	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1116	my $entries = shift
		1117	or return $grp->result ();
		1118
		1119	# stat the dir another time
		1120	aioreq_pri $pri;
962	add $grp aio_stat $path, sub {	1121	add $grp aio_stat $wd, sub {
963	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1122	my $hash2 = join ":", (stat _)[0,1,3,7,9];
964		1123
965	my $ndirs;	1124	my $ndirs;
966		1125
967	# take the slow route if anything looks fishy	1126	# take the slow route if anything looks fishy
968	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1127	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
969	$ndirs = -1;	1128	$ndirs = -1;
970	} else {	1129	} else {
971	# if nlink == 2, we are finished	1130	# if nlink == 2, we are finished
972	# for non-posix-fs's, we rely on nlink < 2	1131	# for non-posix-fs's, we rely on nlink < 2
973	$ndirs = (stat _)[3] - 2	1132	$ndirs = (stat _)[3] - 2
974	or return $grp->result ([], $entries);	1133	or return $grp->result ([], $entries);
975	}	1134	}
976		1135
977	my (@dirs, @nondirs);	1136	my (@dirs, @nondirs);
978		1137
979	my $statgrp = add $grp aio_group sub {	1138	my $statgrp = add $grp aio_group sub {
980	$grp->result (\@dirs, \@nondirs);	1139	$grp->result (\@dirs, \@nondirs);
981	};	1140	};
982		1141
983	limit $statgrp $maxreq;	1142	limit $statgrp $maxreq;
984	feed $statgrp sub {	1143	feed $statgrp sub {
985	return unless @$entries;	1144	return unless @$entries;
986	my $entry = shift @$entries;	1145	my $entry = shift @$entries;
987		1146
988	aioreq_pri $pri;	1147	aioreq_pri $pri;
		1148	$wd->[1] = "$entry/.";
989	add $statgrp aio_stat "$path/$entry/.", sub {	1149	add $statgrp aio_stat $wd, sub {
990	if ($_[0] < 0) {	1150	if ($_[0] < 0) {
991	push @nondirs, $entry;	1151	push @nondirs, $entry;
992	} else {	1152	} else {
993	# need to check for real directory	1153	# need to check for real directory
994	aioreq_pri $pri;	1154	aioreq_pri $pri;
		1155	$wd->[1] = $entry;
995	add $statgrp aio_lstat "$path/$entry", sub {	1156	add $statgrp aio_lstat $wd, sub {
996	if (-d _) {	1157	if (-d _) {
997	push @dirs, $entry;	1158	push @dirs, $entry;
998		1159
999	unless (--$ndirs) {	1160	unless (--$ndirs) {
1000	push @nondirs, @$entries;	1161	push @nondirs, @$entries;
1001	feed $statgrp;	1162	feed $statgrp;
		1163	}
		1164	} else {
		1165	push @nondirs, $entry;
1002	}	1166	}
1003	} else {
1004	push @nondirs, $entry;
1005	}	1167	}
1006	}	1168	}
1007	}	1169	};
1008	};	1170	};
1009	};	1171	};
1010	};	1172	};
1011	};	1173	};
1012	};	1174	};
1013		1175
1014	$grp	1176	$grp
1015	}	1177	}
1016		1178
1017	=item aio_rmtree $path, $callback->($status)	1179	=item aio_rmtree $pathname, $callback->($status)
1018		1180
1019	Delete a directory tree starting (and including) C<$path>, return the	1181	Delete a directory tree starting (and including) C<$path>, return the
1020	status of the final C<rmdir> only. This is a composite request that	1182	status of the final C<rmdir> only. This is a composite request that
1021	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1183	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1022	everything else.	1184	everything else.
1023		1185
1024	=cut	1186	=cut
1025		1187
…		…
1047	};	1209	};
1048		1210
1049	$grp	1211	$grp
1050	}	1212	}
1051		1213
		1214	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1215
		1216	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1217
		1218	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1219	they execute asynchronously and pass the return value to the callback.
		1220
		1221	Both calls can be used for a lot of things, some of which make more sense
		1222	to run asynchronously in their own thread, while some others make less
		1223	sense. For example, calls that block waiting for external events, such
		1224	as locking, will also lock down an I/O thread while it is waiting, which
		1225	can deadlock the whole I/O system. At the same time, there might be no
		1226	alternative to using a thread to wait.
		1227
		1228	So in general, you should only use these calls for things that do
		1229	(filesystem) I/O, not for things that wait for other events (network,
		1230	other processes), although if you are careful and know what you are doing,
		1231	you still can.
		1232
		1233	The following constants are available (missing ones are, as usual C<0>):
		1234
		1235	C<F_DUPFD_CLOEXEC>,
		1236
		1237	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1238
		1239	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1240
		1241	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1242	C<FS_IOC_FIEMAP>.
		1243
		1244	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1245	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1246
		1247	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1248	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1249	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1250	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1251	C<FS_FL_USER_MODIFIABLE>.
		1252
		1253	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1254	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1255	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1256	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1257
1052	=item aio_sync $callback->($status)	1258	=item aio_sync $callback->($status)
1053		1259
1054	Asynchronously call sync and call the callback when finished.	1260	Asynchronously call sync and call the callback when finished.
1055		1261
1056	=item aio_fsync $fh, $callback->($status)	1262	=item aio_fsync $fh, $callback->($status)
…		…
1063	Asynchronously call fdatasync on the given filehandle and call the	1269	Asynchronously call fdatasync on the given filehandle and call the
1064	callback with the fdatasync result code.	1270	callback with the fdatasync result code.
1065		1271
1066	If this call isn't available because your OS lacks it or it couldn't be	1272	If this call isn't available because your OS lacks it or it couldn't be
1067	detected, it will be emulated by calling C<fsync> instead.	1273	detected, it will be emulated by calling C<fsync> instead.
		1274
		1275	=item aio_syncfs $fh, $callback->($status)
		1276
		1277	Asynchronously call the syncfs syscall to sync the filesystem associated
		1278	to the given filehandle and call the callback with the syncfs result
		1279	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1280	errno to C<ENOSYS> nevertheless.
1068		1281
1069	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1282	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1070		1283
1071	Sync the data portion of the file specified by C<$offset> and C<$length>	1284	Sync the data portion of the file specified by C<$offset> and C<$length>
1072	to disk (but NOT the metadata), by calling the Linux-specific	1285	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1076	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1289	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1077	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1290	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1078	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1291	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1079	manpage for details.	1292	manpage for details.
1080		1293
1081	=item aio_pathsync $path, $callback->($status)	1294	=item aio_pathsync $pathname, $callback->($status)
1082		1295
1083	This request tries to open, fsync and close the given path. This is a	1296	This request tries to open, fsync and close the given path. This is a
1084	composite request intended to sync directories after directory operations	1297	composite request intended to sync directories after directory operations
1085	(E.g. rename). This might not work on all operating systems or have any	1298	(E.g. rename). This might not work on all operating systems or have any
1086	specific effect, but usually it makes sure that directory changes get	1299	specific effect, but usually it makes sure that directory changes get
…		…
1117	};	1330	};
1118		1331
1119	$grp	1332	$grp
1120	}	1333	}
1121		1334
1122	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1335	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1123		1336
1124	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1337	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1125	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1338	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1126	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1339	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1127	scalar must only be modified in-place while an aio operation is pending on	1340	scalar must only be modified in-place while an aio operation is pending on
…		…
1129		1342
1130	It calls the C<msync> function of your OS, if available, with the memory	1343	It calls the C<msync> function of your OS, if available, with the memory
1131	area starting at C<$offset> in the string and ending C<$length> bytes	1344	area starting at C<$offset> in the string and ending C<$length> bytes
1132	later. If C<$length> is negative, counts from the end, and if C<$length>	1345	later. If C<$length> is negative, counts from the end, and if C<$length>
1133	is C<undef>, then it goes till the end of the string. The flags can be	1346	is C<undef>, then it goes till the end of the string. The flags can be
1134	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1347	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1135	C<IO::AIO::MS_SYNC>.	1348	C<IO::AIO::MS_INVALIDATE>.
1136		1349
1137	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1350	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1138		1351
1139	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1352	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1140	scalars.	1353	scalars.
1141		1354
1142	It touches (reads or writes) all memory pages in the specified	1355	It touches (reads or writes) all memory pages in the specified
1143	range inside the scalar. All caveats and parameters are the same	1356	range inside the scalar. All caveats and parameters are the same
1144	as for C<aio_msync>, above, except for flags, which must be either	1357	as for C<aio_msync>, above, except for flags, which must be either
1145	C<0> (which reads all pages and ensures they are instantiated) or	1358	C<0> (which reads all pages and ensures they are instantiated) or
1146	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1359	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1147	writing an octet from it, which dirties the page).	1360	writing an octet from it, which dirties the page).
1148		1361
1149	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1362	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1150		1363
1151	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1364	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1182	documented under L<MISCELLANEOUS FUNCTIONS>.	1395	documented under L<MISCELLANEOUS FUNCTIONS>.
1183		1396
1184	Example: asynchronously lock all current and future pages into memory.	1397	Example: asynchronously lock all current and future pages into memory.
1185		1398
1186	aio_mlockall IO::AIO::MCL_FUTURE;	1399	aio_mlockall IO::AIO::MCL_FUTURE;
		1400
		1401	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1402
		1403	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1404	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1405	the ioctl is not available on your OS, then this request will fail with
		1406	C<ENOSYS>.
		1407
		1408	C<$start> is the starting offset to query extents for, C<$length> is the
		1409	size of the range to query - if it is C<undef>, then the whole file will
		1410	be queried.
		1411
		1412	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1413	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1414	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1415	the data portion.
		1416
		1417	C<$count> is the maximum number of extent records to return. If it is
		1418	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1419	case, if it is C<0>, then the callback receives the number of extents
		1420	instead of the extents themselves (which is unreliable, see below).
		1421
		1422	If an error occurs, the callback receives no arguments. The special
		1423	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1424
		1425	Otherwise, the callback receives an array reference with extent
		1426	structures. Each extent structure is an array reference itself, with the
		1427	following members:
		1428
		1429	[$logical, $physical, $length, $flags]
		1430
		1431	Flags is any combination of the following flag values (typically either C<0>
		1432	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1433
		1434	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1435	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1436	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1437	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1438	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1439	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1440
		1441	At the time of this writing (Linux 3.2), this request is unreliable unless
		1442	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1443	it to return all extents of a range for files with a large number of
		1444	extents. The code (only) works around all these issues if C<$count> is
		1445	C<undef>.
1187		1446
1188	=item aio_group $callback->(...)	1447	=item aio_group $callback->(...)
1189		1448
1190	This is a very special aio request: Instead of doing something, it is a	1449	This is a very special aio request: Instead of doing something, it is a
1191	container for other aio requests, which is useful if you want to bundle	1450	container for other aio requests, which is useful if you want to bundle
…		…
1228	like sleep and file handle readable/writable, the overhead this creates is	1487	like sleep and file handle readable/writable, the overhead this creates is
1229	immense (it blocks a thread for a long time) so do not use this function	1488	immense (it blocks a thread for a long time) so do not use this function
1230	except to put your application under artificial I/O pressure.	1489	except to put your application under artificial I/O pressure.
1231		1490
1232	=back	1491	=back
		1492
		1493
		1494	=head2 IO::AIO::WD - multiple working directories
		1495
		1496	Your process only has one current working directory, which is used by all
		1497	threads. This makes it hard to use relative paths (some other component
		1498	could call C<chdir> at any time, and it is hard to control when the path
		1499	will be used by IO::AIO).
		1500
		1501	One solution for this is to always use absolute paths. This usually works,
		1502	but can be quite slow (the kernel has to walk the whole path on every
		1503	access), and can also be a hassle to implement.
		1504
		1505	Newer POSIX systems have a number of functions (openat, fdopendir,
		1506	futimensat and so on) that make it possible to specify working directories
		1507	per operation.
		1508
		1509	For portability, and because the clowns who "designed", or shall I write,
		1510	perpetrated this new interface were obviously half-drunk, this abstraction
		1511	cannot be perfect, though.
		1512
		1513	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1514	object. This object stores the canonicalised, absolute version of the
		1515	path, and on systems that allow it, also a directory file descriptor.
		1516
		1517	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1518	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1519	object and a pathname instead (or the IO::AIO::WD object alone, which
		1520	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1521	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1522	to that IO::AIO::WD object.
		1523
		1524	For example, to get a wd object for F</etc> and then stat F<passwd>
		1525	inside, you would write:
		1526
		1527	aio_wd "/etc", sub {
		1528	my $etcdir = shift;
		1529
		1530	# although $etcdir can be undef on error, there is generally no reason
		1531	# to check for errors here, as aio_stat will fail with ENOENT
		1532	# when $etcdir is undef.
		1533
		1534	aio_stat [$etcdir, "passwd"], sub {
		1535	# yay
		1536	};
		1537	};
		1538
		1539	The fact that C<aio_wd> is a request and not a normal function shows that
		1540	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1541	which is why it is done asynchronously.
		1542
		1543	To stat the directory obtained with C<aio_wd> above, one could write
		1544	either of the following three request calls:
		1545
		1546	aio_lstat "/etc" , sub { ... # pathname as normal string
		1547	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1548	aio_lstat $wd , sub { ... # shorthand for the previous
		1549
		1550	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1551	object and the pathname string, so you could write the following without
		1552	causing any issues due to C<$path> getting reused:
		1553
		1554	my $path = [$wd, undef];
		1555
		1556	for my $name (qw(abc def ghi)) {
		1557	$path->[1] = $name;
		1558	aio_stat $path, sub {
		1559	# ...
		1560	};
		1561	}
		1562
		1563	There are some caveats: when directories get renamed (or deleted), the
		1564	pathname string doesn't change, so will point to the new directory (or
		1565	nowhere at all), while the directory fd, if available on the system,
		1566	will still point to the original directory. Most functions accepting a
		1567	pathname will use the directory fd on newer systems, and the string on
		1568	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1569	the string form of the pathname.
		1570
		1571	So this functionality is mainly useful to get some protection against
		1572	C<chdir>, to easily get an absolute path out of a relative path for future
		1573	reference, and to speed up doing many operations in the same directory
		1574	(e.g. when stat'ing all files in a directory).
		1575
		1576	The following functions implement this working directory abstraction:
		1577
		1578	=over 4
		1579
		1580	=item aio_wd $pathname, $callback->($wd)
		1581
		1582	Asynchonously canonicalise the given pathname and convert it to an
		1583	IO::AIO::WD object representing it. If possible and supported on the
		1584	system, also open a directory fd to speed up pathname resolution relative
		1585	to this working directory.
		1586
		1587	If something goes wrong, then C<undef> is passwd to the callback instead
		1588	of a working directory object and C<$!> is set appropriately. Since
		1589	passing C<undef> as working directory component of a pathname fails the
		1590	request with C<ENOENT>, there is often no need for error checking in the
		1591	C<aio_wd> callback, as future requests using the value will fail in the
		1592	expected way.
		1593
		1594	=item IO::AIO::CWD
		1595
		1596	This is a compiletime constant (object) that represents the process
		1597	current working directory.
		1598
		1599	Specifying this object as working directory object for a pathname is as if
		1600	the pathname would be specified directly, without a directory object. For
		1601	example, these calls are functionally identical:
		1602
		1603	aio_stat "somefile", sub { ... };
		1604	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1605
		1606	=back
		1607
		1608	To recover the path associated with an IO::AIO::WD object, you can use
		1609	C<aio_realpath>:
		1610
		1611	aio_realpath $wd, sub {
		1612	warn "path is $_[0]\n";
		1613	};
		1614
		1615	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1616	sometimes, fall back to using an absolue path.
1233		1617
1234	=head2 IO::AIO::REQ CLASS	1618	=head2 IO::AIO::REQ CLASS
1235		1619
1236	All non-aggregate C<aio_*> functions return an object of this class when	1620	All non-aggregate C<aio_*> functions return an object of this class when
1237	called in non-void context.	1621	called in non-void context.
…		…
1355		1739
1356	Sets a feeder/generator on this group: every group can have an attached	1740	Sets a feeder/generator on this group: every group can have an attached
1357	generator that generates requests if idle. The idea behind this is that,	1741	generator that generates requests if idle. The idea behind this is that,
1358	although you could just queue as many requests as you want in a group,	1742	although you could just queue as many requests as you want in a group,
1359	this might starve other requests for a potentially long time. For example,	1743	this might starve other requests for a potentially long time. For example,
1360	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1744	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1361	delaying any later requests for a long time.	1745	requests, delaying any later requests for a long time.
1362		1746
1363	To avoid this, and allow incremental generation of requests, you can	1747	To avoid this, and allow incremental generation of requests, you can
1364	instead a group and set a feeder on it that generates those requests. The	1748	instead a group and set a feeder on it that generates those requests. The
1365	feed callback will be called whenever there are few enough (see C<limit>,	1749	feed callback will be called whenever there are few enough (see C<limit>,
1366	below) requests active in the group itself and is expected to queue more	1750	below) requests active in the group itself and is expected to queue more
…		…
1415		1799
1416	See C<poll_cb> for an example.	1800	See C<poll_cb> for an example.
1417		1801
1418	=item IO::AIO::poll_cb	1802	=item IO::AIO::poll_cb
1419		1803
1420	Process some outstanding events on the result pipe. You have to call	1804	Process some requests that have reached the result phase (i.e. they have
		1805	been executed but the results are not yet reported). You have to call
		1806	this "regularly" to finish outstanding requests.
		1807
1421	this regularly. Returns C<0> if all events could be processed (or there	1808	Returns C<0> if all events could be processed (or there were no
1422	were no events to process), or C<-1> if it returned earlier for whatever	1809	events to process), or C<-1> if it returned earlier for whatever
1423	reason. Returns immediately when no events are outstanding. The amount of	1810	reason. Returns immediately when no events are outstanding. The amount
1424	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1811	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1425	C<IO::AIO::max_poll_time>.	1812	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1426		1813
1427	If not all requests were processed for whatever reason, the filehandle	1814	If not all requests were processed for whatever reason, the poll file
1428	will still be ready when C<poll_cb> returns, so normally you don't have to	1815	descriptor will still be ready when C<poll_cb> returns, so normally you
1429	do anything special to have it called later.	1816	don't have to do anything special to have it called later.
1430		1817
1431	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1818	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1432	ready, it can be beneficial to call this function from loops which submit	1819	ready, it can be beneficial to call this function from loops which submit
1433	a lot of requests, to make sure the results get processed when they become	1820	a lot of requests, to make sure the results get processed when they become
1434	available and not just when the loop is finished and the event loop takes	1821	available and not just when the loop is finished and the event loop takes
…		…
1443	poll => 'r', async => 1,	1830	poll => 'r', async => 1,
1444	cb => \&IO::AIO::poll_cb);	1831	cb => \&IO::AIO::poll_cb);
1445		1832
1446	=item IO::AIO::poll_wait	1833	=item IO::AIO::poll_wait
1447		1834
1448	If there are any outstanding requests and none of them in the result	1835	Wait until either at least one request is in the result phase or no
1449	phase, wait till the result filehandle becomes ready for reading (simply	1836	requests are outstanding anymore.
1450	does a C<select> on the filehandle. This is useful if you want to	1837
1451	synchronously wait for some requests to finish).	1838	This is useful if you want to synchronously wait for some requests to
		1839	become ready, without actually handling them.
1452		1840
1453	See C<nreqs> for an example.	1841	See C<nreqs> for an example.
1454		1842
1455	=item IO::AIO::poll	1843	=item IO::AIO::poll
1456		1844
…		…
1577		1965
1578	This is a very bad function to use in interactive programs because it	1966	This is a very bad function to use in interactive programs because it
1579	blocks, and a bad way to reduce concurrency because it is inexact: Better	1967	blocks, and a bad way to reduce concurrency because it is inexact: Better
1580	use an C<aio_group> together with a feed callback.	1968	use an C<aio_group> together with a feed callback.
1581		1969
1582	It's main use is in scripts without an event loop - when you want to stat	1970	Its main use is in scripts without an event loop - when you want to stat
1583	a lot of files, you can write somehting like this:	1971	a lot of files, you can write something like this:
1584		1972
1585	IO::AIO::max_outstanding 32;	1973	IO::AIO::max_outstanding 32;
1586		1974
1587	for my $path (...) {	1975	for my $path (...) {
1588	aio_stat $path , ...;	1976	aio_stat $path , ...;
…		…
1625	Returns the number of requests currently in the pending state (executed,	2013	Returns the number of requests currently in the pending state (executed,
1626	but not yet processed by poll_cb).	2014	but not yet processed by poll_cb).
1627		2015
1628	=back	2016	=back
1629		2017
		2018	=head3 SUBSECOND STAT TIME ACCESS
		2019
		2020	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2021	generally find access/modification and change times with subsecond time
		2022	accuracy of the system supports it, but perl's built-in functions only
		2023	return the integer part.
		2024
		2025	The following functions return the timestamps of the most recent
		2026	stat with subsecond precision on most systems and work both after
		2027	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2028	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2029	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2030
		2031	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2032	full resolution without rounding and work with standard perl C<stat>,
		2033	alleviating the need to call the special C<Time::HiRes> functions, which
		2034	do not act like their perl counterparts.
		2035
		2036	On operating systems or file systems where subsecond time resolution is
		2037	not supported or could not be detected, a fractional part of C<0> is
		2038	returned, so it is always safe to call these functions.
		2039
		2040	=over 4
		2041
		2042	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime
		2043
		2044	Return the access, modication or change time, respectively, including
		2045	fractional part. Due to the limited precision of floating point, the
		2046	accuracy on most platforms is only a bit better than milliseconds for
		2047	times around now - see the I<nsec> function family, below, for full
		2048	accuracy.
		2049
		2050	=item ($atime, $mtime, $ctime, ...) = IO::AIO::st_xtime
		2051
		2052	Returns access, modification and change time all in one go, and maybe more
		2053	times in the future version.
		2054
		2055	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec
		2056
		2057	Return the fractional access, modifcation or change time, in nanoseconds,
		2058	as an integer in the range C<0> to C<999999999>.
		2059
		2060	=item ($atime, $mtime, $ctime, ...) = IO::AIO::st_xtimensec
		2061
		2062	Like the functions above, but returns all three times in one go (and maybe
		2063	more in future versions).
		2064
		2065	=back
		2066
		2067	Example: print the high resolution modification time of F</etc>, using
		2068	C<stat>, and C<IO::AIO::aio_stat>.
		2069
		2070	if (stat "/etc") {
		2071	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2072	}
		2073
		2074	IO::AIO::aio_stat "/etc", sub {
		2075	$_[0]
		2076	and return;
		2077
		2078	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2079	};
		2080
		2081	IO::AIO::flush;
		2082
		2083	Output of the awbove on my system, showing reduced and full accuracy:
		2084
		2085	stat(/etc) mtime: 1534043702.020808
		2086	aio_stat(/etc) mtime: 1534043702.020807792
		2087
1630	=head3 MISCELLANEOUS FUNCTIONS	2088	=head3 MISCELLANEOUS FUNCTIONS
1631		2089
1632	IO::AIO implements some functions that might be useful, but are not	2090	IO::AIO implements some functions that are useful when you want to use
1633	asynchronous.	2091	some "Advanced I/O" function not available to in Perl, without going the
		2092	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2093	counterpart.
1634		2094
1635	=over 4	2095	=over 4
		2096
		2097	=item $numfd = IO::AIO::get_fdlimit
		2098
		2099	This function is I<EXPERIMENTAL> and subject to change.
		2100
		2101	Tries to find the current file descriptor limit and returns it, or
		2102	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2103	the highest valid file descriptor number.
		2104
		2105	=item IO::AIO::min_fdlimit [$numfd]
		2106
		2107	This function is I<EXPERIMENTAL> and subject to change.
		2108
		2109	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2110	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2111	is missing, it will try to set a very high limit, although this is not
		2112	recommended when you know the actual minimum that you require.
		2113
		2114	If the limit cannot be raised enough, the function makes a best-effort
		2115	attempt to increase the limit as much as possible, using various
		2116	tricks, while still failing. You can query the resulting limit using
		2117	C<IO::AIO::get_fdlimit>.
		2118
		2119	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2120	true.
1636		2121
1637	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2122	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1638		2123
1639	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2124	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1640	but is blocking (this makes most sense if you know the input data is	2125	but is blocking (this makes most sense if you know the input data is
…		…
1645		2130
1646	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2131	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1647		2132
1648	Simply calls the C<posix_fadvise> function (see its	2133	Simply calls the C<posix_fadvise> function (see its
1649	manpage for details). The following advice constants are	2134	manpage for details). The following advice constants are
1650	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2135	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1651	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2136	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1652	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2137	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1653		2138
1654	On systems that do not implement C<posix_fadvise>, this function returns	2139	On systems that do not implement C<posix_fadvise>, this function returns
1655	ENOSYS, otherwise the return value of C<posix_fadvise>.	2140	ENOSYS, otherwise the return value of C<posix_fadvise>.
1656		2141
1657	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2142	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1658		2143
1659	Simply calls the C<posix_madvise> function (see its	2144	Simply calls the C<posix_madvise> function (see its
1660	manpage for details). The following advice constants are	2145	manpage for details). The following advice constants are
1661	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2146	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1662	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2147	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2148	C<IO::AIO::MADV_DONTNEED>.
		2149
		2150	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2151	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2152	will be reduced to fit into the C<$scalar>.
1663		2153
1664	On systems that do not implement C<posix_madvise>, this function returns	2154	On systems that do not implement C<posix_madvise>, this function returns
1665	ENOSYS, otherwise the return value of C<posix_madvise>.	2155	ENOSYS, otherwise the return value of C<posix_madvise>.
1666		2156
1667	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2157	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1668		2158
1669	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2159	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1670	$scalar (see its manpage for details). The following protect	2160	$scalar (see its manpage for details). The following protect
1671	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2161	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1672	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2162	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2163
		2164	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2165	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2166	will be reduced to fit into the C<$scalar>.
1673		2167
1674	On systems that do not implement C<mprotect>, this function returns	2168	On systems that do not implement C<mprotect>, this function returns
1675	ENOSYS, otherwise the return value of C<mprotect>.	2169	ENOSYS, otherwise the return value of C<mprotect>.
1676		2170
1677	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2171	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1678		2172
1679	Memory-maps a file (or anonymous memory range) and attaches it to the	2173	Memory-maps a file (or anonymous memory range) and attaches it to the
1680	given C<$scalar>, which will act like a string scalar.	2174	given C<$scalar>, which will act like a string scalar. Returns true on
		2175	success, and false otherwise.
1681		2176
		2177	The scalar must exist, but its contents do not matter - this means you
		2178	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2179	the scalar first.
		2180
1682	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2181	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1683	change the string length, and most read-only operations such as copying it	2182	which don't change the string length, and most read-only operations such
1684	or searching it with regexes and so on.	2183	as copying it or searching it with regexes and so on.
1685		2184
1686	Anything else is unsafe and will, at best, result in memory leaks.	2185	Anything else is unsafe and will, at best, result in memory leaks.
1687		2186
1688	The memory map associated with the C<$scalar> is automatically removed	2187	The memory map associated with the C<$scalar> is automatically removed
1689	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2188	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1690	C<IO::AIO::munmap> functions are called.	2189	or C<IO::AIO::munmap> functions are called on it.
1691		2190
1692	This calls the C<mmap>(2) function internally. See your system's manual	2191	This calls the C<mmap>(2) function internally. See your system's manual
1693	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2192	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1694		2193
1695	The C<$length> must be larger than zero and smaller than the actual	2194	The C<$length> must be larger than zero and smaller than the actual
1696	filesize.	2195	filesize.
1697		2196
1698	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2197	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1699	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2198	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1700		2199
1701	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2200	C<$flags> can be a combination of
1702	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2201	C<IO::AIO::MAP_SHARED> or
1703	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2202	C<IO::AIO::MAP_PRIVATE>,
		2203	or a number of system-specific flags (when not available, the are C<0>):
1704	(which is set to C<MAP_ANON> if your system only provides this	2204	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1705	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2205	C<IO::AIO::MAP_LOCKED>,
1706	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2206	C<IO::AIO::MAP_NORESERVE>,
		2207	C<IO::AIO::MAP_POPULATE>,
1707	C<IO::AIO::MAP_NONBLOCK>	2208	C<IO::AIO::MAP_NONBLOCK>,
		2209	C<IO::AIO::MAP_FIXED>,
		2210	C<IO::AIO::MAP_GROWSDOWN>,
		2211	C<IO::AIO::MAP_32BIT>,
		2212	C<IO::AIO::MAP_HUGETLB> or
		2213	C<IO::AIO::MAP_STACK>.
1708		2214
1709	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2215	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1710		2216
1711	C<$offset> is the offset from the start of the file - it generally must be	2217	C<$offset> is the offset from the start of the file - it generally must be
1712	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2218	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1726		2232
1727	=item IO::AIO::munmap $scalar	2233	=item IO::AIO::munmap $scalar
1728		2234
1729	Removes a previous mmap and undefines the C<$scalar>.	2235	Removes a previous mmap and undefines the C<$scalar>.
1730		2236
		2237	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2238
		2239	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2240	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2241	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2242
		2243	Returns true if successful, and false otherwise. If the underlying mmapped
		2244	region has changed address, then the true value has the numerical value
		2245	C<1>, otherwise it has the numerical value C<0>:
		2246
		2247	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2248	or die "mremap: $!";
		2249
		2250	if ($success*1) {
		2251	warn "scalar has chanegd address in memory\n";
		2252	}
		2253
		2254	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2255	implemented, but not supported and might go away in a future version.
		2256
		2257	On systems where this call is not supported or is not emulated, this call
		2258	returns falls and sets C<$!> to C<ENOSYS>.
		2259
1731	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2260	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1732		2261
1733	Calls the C<munlock> function, undoing the effects of a previous	2262	Calls the C<munlock> function, undoing the effects of a previous
1734	C<aio_mlock> call (see its description for details).	2263	C<aio_mlock> call (see its description for details).
1735		2264
…		…
1737		2266
1738	Calls the C<munlockall> function.	2267	Calls the C<munlockall> function.
1739		2268
1740	On systems that do not implement C<munlockall>, this function returns	2269	On systems that do not implement C<munlockall>, this function returns
1741	ENOSYS, otherwise the return value of C<munlockall>.	2270	ENOSYS, otherwise the return value of C<munlockall>.
		2271
		2272	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2273
		2274	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2275	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2276	should be the file offset.
		2277
		2278	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2279	silently corrupt the data in this case.
		2280
		2281	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2282	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2283	C<IO::AIO::SPLICE_F_GIFT>.
		2284
		2285	See the C<splice(2)> manpage for details.
		2286
		2287	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2288
		2289	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2290	description for C<IO::AIO::splice> above for details.
		2291
		2292	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2293
		2294	Attempts to query or change the pipe buffer size. Obviously works only
		2295	on pipes, and currently works only on GNU/Linux systems, and fails with
		2296	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2297	size on other systems, drop me a note.
		2298
		2299	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2300
		2301	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2302	C<$flags> is missing or C<0>, then this should be the same as a call to
		2303	perl's built-in C<pipe> function and create a new pipe, and works on
		2304	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2305	(..., 4096, O_BINARY)>.
		2306
		2307	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2308	the given flags (Linux 2.6.27, glibc 2.9).
		2309
		2310	On success, the read and write file handles are returned.
		2311
		2312	On error, nothing will be returned. If the pipe2 syscall is missing and
		2313	C<$flags> is non-zero, fails with C<ENOSYS>.
		2314
		2315	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2316	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2317	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2318
		2319	Example: create a pipe race-free w.r.t. threads and fork:
		2320
		2321	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2322	or die "pipe2: $!\n";
		2323
		2324	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2325
		2326	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2327	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2328
		2329	On success, the new eventfd filehandle is returned, otherwise returns
		2330	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2331
		2332	Please refer to L<eventfd(2)> for more info on this call.
		2333
		2334	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2335	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2336
		2337	Example: create a new eventfd filehandle:
		2338
		2339	$fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC
		2340	or die "eventfd: $!\n";
		2341
		2342	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2343
		2344	This is a direct interface to the Linux L<timerfd_create(2)> system call. The
		2345	(unhelpful) default for C<$flags> is C<0>.
		2346
		2347	On success, the new timerfd filehandle is returned, otherwise returns
		2348	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2349
		2350	Please refer to L<timerfd_create(2)> for more info on this call.
		2351
		2352	The following C<$clockid> values are
		2353	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2354	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2355	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2356	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2357
		2358	The following C<$flags> values are available (Linux
		2359	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2360
		2361	Example: create a new timerfd and set it to one-second repeated alarms,
		2362	then wait for two alarms:
		2363
		2364	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2365	or die "timerfd_create: $!\n";
		2366
		2367	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2368	or die "timerfd_settime: $!\n";
		2369
		2370	for (1..2) {
		2371	8 == sysread $fh, my $buf, 8
		2372	or die "timerfd read failure\n";
		2373
		2374	printf "number of expirations (likely 1): %d\n",
		2375	unpack "Q", $buf;
		2376	}
		2377
		2378	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2379
		2380	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2381	call. Please refer to its manpage for more info on this call.
		2382
		2383	The new itimerspec is specified using two (possibly fractional) second
		2384	values, C<$new_interval> and C<$new_value>).
		2385
		2386	On success, the current interval and value are returned (as per
		2387	C<timerfd_gettime>). On failure, the empty list is returned.
		2388
		2389	The following C<$flags> values are
		2390	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2391	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2392
		2393	See C<IO::AIO::timerfd_create> for a full example.
		2394
		2395	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2396
		2397	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2398	call. Please refer to its manpage for more info on this call.
		2399
		2400	On success, returns the current values of interval and value for the given
		2401	timerfd (as potentially fractional second values). On failure, the empty
		2402	list is returned.
1742		2403
1743	=back	2404	=back
1744		2405
1745	=cut	2406	=cut
1746		2407
…		…
1781	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2442	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1782	\&IO::AIO::poll_cb);	2443	\&IO::AIO::poll_cb);
1783		2444
1784	=head2 FORK BEHAVIOUR	2445	=head2 FORK BEHAVIOUR
1785		2446
1786	This module should do "the right thing" when the process using it forks:	2447	Usage of pthreads in a program changes the semantics of fork
		2448	considerably. Specifically, only async-safe functions can be called after
		2449	fork. Perl doesn't know about this, so in general, you cannot call fork
		2450	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2451	pthreads, so this applies, but many other extensions and (for inexplicable
		2452	reasons) perl itself often is linked against pthreads, so this limitation
		2453	applies to quite a lot of perls.
1787		2454
1788	Before the fork, IO::AIO enters a quiescent state where no requests	2455	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1789	can be added in other threads and no results will be processed. After	2456	only works in the process that loaded it. Forking is fully supported, but
1790	the fork the parent simply leaves the quiescent state and continues	2457	using IO::AIO in the child is not.
1791	request/result processing, while the child frees the request/result queue
1792	(so that the requests started before the fork will only be handled in the
1793	parent). Threads will be started on demand until the limit set in the
1794	parent process has been reached again.
1795		2458
1796	In short: the parent will, after a short pause, continue as if fork had	2459	You might get around by not I<using> IO::AIO before (or after)
1797	not been called, while the child will act as if IO::AIO has not been used	2460	forking. You could also try to call the L<IO::AIO::reinit> function in the
1798	yet.	2461	child:
		2462
		2463	=over 4
		2464
		2465	=item IO::AIO::reinit
		2466
		2467	Abandons all current requests and I/O threads and simply reinitialises all
		2468	data structures. This is not an operation supported by any standards, but
		2469	happens to work on GNU/Linux and some newer BSD systems.
		2470
		2471	The only reasonable use for this function is to call it after forking, if
		2472	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2473	the process will result in undefined behaviour. Calling it at any time
		2474	will also result in any undefined (by POSIX) behaviour.
		2475
		2476	=back
		2477
		2478	=head2 LINUX-SPECIFIC CALLS
		2479
		2480	When a call is documented as "linux-specific" then this means it
		2481	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2482	availability and compatibility of such calls regardless of the platform
		2483	it is compiled on, so platforms such as FreeBSD which often implement
		2484	these calls will work. When in doubt, call them and see if they fail wth
		2485	C<ENOSYS>.
1799		2486
1800	=head2 MEMORY USAGE	2487	=head2 MEMORY USAGE
1801		2488
1802	Per-request usage:	2489	Per-request usage:
1803		2490
…		…
1816	temporary buffers, and each thread requires a stack and other data	2503	temporary buffers, and each thread requires a stack and other data
1817	structures (usually around 16k-128k, depending on the OS).	2504	structures (usually around 16k-128k, depending on the OS).
1818		2505
1819	=head1 KNOWN BUGS	2506	=head1 KNOWN BUGS
1820		2507
1821	Known bugs will be fixed in the next release.	2508	Known bugs will be fixed in the next release :)
		2509
		2510	=head1 KNOWN ISSUES
		2511
		2512	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2513	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2514	non-created hash slots or other scalars I didn't think of. It's best to
		2515	avoid such and either use scalar variables or making sure that the scalar
		2516	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2517
		2518	I am not sure anything can be done about this, so this is considered a
		2519	known issue, rather than a bug.
1822		2520
1823	=head1 SEE ALSO	2521	=head1 SEE ALSO
1824		2522
1825	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2523	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1826	more natural syntax.	2524	more natural syntax.

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