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Revision 1.187 by root, Fri Feb 11 00:05:17 2011 UTC vs.
Revision 1.283 by root, Tue Feb 20 06:05:19 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 = '3.72';	176	our $VERSION = 4.4;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		182	aio_pathsync aio_readahead aio_fiemap aio_allocate
179	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
181	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
182	aio_msync aio_mtouch aio_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	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 munlock munlockall);
192		198
…		…
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->()
…		…
258	IO::AIO::max_poll_reqs $nreqs	273	IO::AIO::max_poll_reqs $nreqs
259	IO::AIO::max_poll_time $seconds	274	IO::AIO::max_poll_time $seconds
260	IO::AIO::min_parallel $nthreads	275	IO::AIO::min_parallel $nthreads
261	IO::AIO::max_parallel $nthreads	276	IO::AIO::max_parallel $nthreads
262	IO::AIO::max_idle $nthreads	277	IO::AIO::max_idle $nthreads
		278	IO::AIO::idle_timeout $seconds
263	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
264	IO::AIO::nreqs	280	IO::AIO::nreqs
265	IO::AIO::nready	281	IO::AIO::nready
266	IO::AIO::npending	282	IO::AIO::npending
		283	$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
		284	IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
267		285
268	IO::AIO::sendfile $ofh, $ifh, $offset, $count	286	IO::AIO::sendfile $ofh, $ifh, $offset, $count
269	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
270	IO::AIO::madvise $scalar, $offset, $length, $advice	290	IO::AIO::madvise $scalar, $offset, $length, $advice
271	IO::AIO::mprotect $scalar, $offset, $length, $protect	291	IO::AIO::mprotect $scalar, $offset, $length, $protect
272	IO::AIO::munlock $scalar, $offset = 0, $length = undef	292	IO::AIO::munlock $scalar, $offset = 0, $length = undef
273	IO::AIO::munlockall	293	IO::AIO::munlockall
274		294
275	=head2 AIO REQUEST FUNCTIONS	295	=head2 API NOTES
276		296
277	All the C<aio_*> calls are more or less thin wrappers around the syscall	297	All the C<aio_*> calls are more or less thin wrappers around the syscall
278	with the same name (sans C<aio_>). The arguments are similar or identical,	298	with the same name (sans C<aio_>). The arguments are similar or identical,
279	and they all accept an additional (and optional) C<$callback> argument	299	and they all accept an additional (and optional) C<$callback> argument
280	which must be a code reference. This code reference will get called with	300	which must be a code reference. This code reference will be called after
281	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	301	the syscall has been executed in an asynchronous fashion. The results
282	perl, which usually delivers "false") as its sole argument after the given	302	of the request will be passed as arguments to the callback (and, if an
283	syscall has been executed asynchronously.	303	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		304	most syscalls return C<-1> on error, unlike perl, which usually delivers
		305	"false").
		306
		307	Some requests (such as C<aio_readdir>) pass the actual results and
		308	communicate failures by passing C<undef>.
284		309
285	All functions expecting a filehandle keep a copy of the filehandle	310	All functions expecting a filehandle keep a copy of the filehandle
286	internally until the request has finished.	311	internally until the request has finished.
287		312
288	All functions return request objects of type L<IO::AIO::REQ> that allow	313	All functions return request objects of type L<IO::AIO::REQ> that allow
289	further manipulation of those requests while they are in-flight.	314	further manipulation of those requests while they are in-flight.
290		315
291	The pathnames you pass to these routines I<must> be absolute and	316	The pathnames you pass to these routines I<should> be absolute. The
292	encoded as octets. The reason for the former is that at the time the	317	reason for this is that at the time the request is being executed, the
293	request is being executed, the current working directory could have	318	current working directory could have changed. Alternatively, you can
294	changed. Alternatively, you can make sure that you never change the	319	make sure that you never change the current working directory anywhere
295	current working directory anywhere in the program and then use relative	320	in the program and then use relative paths. You can also take advantage
296	paths.	321	of IO::AIOs working directory abstraction, that lets you specify paths
		322	relative to some previously-opened "working directory object" - see the
		323	description of the C<IO::AIO::WD> class later in this document.
297		324
298	To encode pathnames as octets, either make sure you either: a) always pass	325	To encode pathnames as octets, either make sure you either: a) always pass
299	in filenames you got from outside (command line, readdir etc.) without	326	in filenames you got from outside (command line, readdir etc.) without
300	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	327	tinkering, b) are in your native filesystem encoding, c) use the Encode
301	your pathnames to the locale (or other) encoding in effect in the user	328	module and encode your pathnames to the locale (or other) encoding in
302	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	329	effect in the user environment, d) use Glib::filename_from_unicode on
303	use something else to ensure your scalar has the correct contents.	330	unicode filenames or e) use something else to ensure your scalar has the
		331	correct contents.
304		332
305	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	333	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
306	handles correctly whether it is set or not.	334	handles correctly whether it is set or not.
		335
		336	=head2 AIO REQUEST FUNCTIONS
307		337
308	=over 4	338	=over 4
309		339
310	=item $prev_pri = aioreq_pri [$pri]	340	=item $prev_pri = aioreq_pri [$pri]
311		341
…		…
341		371
342		372
343	=item aio_open $pathname, $flags, $mode, $callback->($fh)	373	=item aio_open $pathname, $flags, $mode, $callback->($fh)
344		374
345	Asynchronously open or create a file and call the callback with a newly	375	Asynchronously open or create a file and call the callback with a newly
346	created filehandle for the file.	376	created filehandle for the file (or C<undef> in case of an error).
347		377
348	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	378	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
349	for an explanation.	379	for an explanation.
350		380
351	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	381	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
367	} else {	397	} else {
368	die "open failed: $!\n";	398	die "open failed: $!\n";
369	}	399	}
370	};	400	};
371		401
		402	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		403	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		404	following POSIX and non-POSIX constants are available (missing ones on
		405	your system are, as usual, C<0>):
		406
		407	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		408	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		409	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		410
372		411
373	=item aio_close $fh, $callback->($status)	412	=item aio_close $fh, $callback->($status)
374		413
375	Asynchronously close a file and call the callback with the result	414	Asynchronously close a file and call the callback with the result
376	code.	415	code.
…		…
385	Or in other words: the file descriptor will be closed, but it will not be	424	Or in other words: the file descriptor will be closed, but it will not be
386	free for reuse until the perl filehandle is closed.	425	free for reuse until the perl filehandle is closed.
387		426
388	=cut	427	=cut
389		428
		429	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		430
		431	Seeks the filehandle to the new C<$offset>, similarly to perl's
		432	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		433	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		434	C<IO::AIO::SEEK_END>).
		435
		436	The resulting absolute offset will be passed to the callback, or C<-1> in
		437	case of an error.
		438
		439	In theory, the C<$whence> constants could be different than the
		440	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		441	so don't panic.
		442
		443	As a GNU/Linux (and maybe Solaris) extension, also the constants
		444	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		445	could be found. No guarantees about suitability for use in C<aio_seek> or
		446	Perl's C<sysseek> can be made though, although I would naively assume they
		447	"just work".
		448
390	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	449	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
391		450
392	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	451	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
393		452
394	Reads or writes C<$length> bytes from or to the specified C<$fh> and	453	Reads or writes C<$length> bytes from or to the specified C<$fh> and
395	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	454	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
396	and calls the callback without the actual number of bytes read (or -1 on	455	calls the callback with the actual number of bytes transferred (or -1 on
397	error, just like the syscall).	456	error, just like the syscall).
398		457
399	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	458	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
400	offset plus the actual number of bytes read.	459	offset plus the actual number of bytes read.
401		460
…		…
426		485
427	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	486	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
428	reading at byte offset C<$in_offset>, and starts writing at the current	487	reading at byte offset C<$in_offset>, and starts writing at the current
429	file offset of C<$out_fh>. Because of that, it is not safe to issue more	488	file offset of C<$out_fh>. Because of that, it is not safe to issue more
430	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	489	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
431	other.	490	other. The same C<$in_fh> works fine though, as this function does not
		491	move or use the file offset of C<$in_fh>.
432		492
433	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than	493	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
434	are written, and there is no way to find out how many bytes have been read	494	are written, and there is no way to find out how many more bytes have been
435	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of	495	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
436	bytes written to C<$out_fh>. Only if the result value equals C<$length>	496	number of bytes written to C<$out_fh>. Only if the result value equals
437	one can assume that C<$length> bytes have been read.	497	C<$length> one can assume that C<$length> bytes have been read.
438		498
439	Unlike with other C<aio_> functions, it makes a lot of sense to use	499	Unlike with other C<aio_> functions, it makes a lot of sense to use
440	C<aio_sendfile> on non-blocking sockets, as long as one end (typically	500	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
441	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while	501	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
442	the socket I/O will be non-blocking. Note, however, that you can run into	502	the socket I/O will be non-blocking. Note, however, that you can run
443	a trap where C<aio_sendfile> reads some data with readahead, then fails	503	into a trap where C<aio_sendfile> reads some data with readahead, then
444	to write all data, and when the socket is ready the next time, the data	504	fails to write all data, and when the socket is ready the next time, the
445	in the cache is already lost, forcing C<aio_sendfile> to again hit the	505	data in the cache is already lost, forcing C<aio_sendfile> to again hit
446	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage	506	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
447	much better.	507	resource usage.
448		508
449	This call tries to make use of a native C<sendfile> syscall to provide	509	This call tries to make use of a native C<sendfile>-like syscall to
450	zero-copy operation. For this to work, C<$out_fh> should refer to a	510	provide zero-copy operation. For this to work, C<$out_fh> should refer to
451	socket, and C<$in_fh> should refer to an mmap'able file.	511	a socket, and C<$in_fh> should refer to an mmap'able file.
452		512
453	If a native sendfile cannot be found or it fails with C<ENOSYS>,	513	If a native sendfile cannot be found or it fails with C<ENOSYS>,
454	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	514	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
455	it will be emulated, so you can call C<aio_sendfile> on any type of	515	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
456	filehandle regardless of the limitations of the operating system.	516	type of filehandle regardless of the limitations of the operating system.
		517
		518	As native sendfile syscalls (as practically any non-POSIX interface hacked
		519	together in a hurry to improve benchmark numbers) tend to be rather buggy
		520	on many systems, this implementation tries to work around some known bugs
		521	in Linux and FreeBSD kernels (probably others, too), but that might fail,
		522	so you really really should check the return value of C<aio_sendfile> -
		523	fewer bytes than expected might have been transferred.
457		524
458		525
459	=item aio_readahead $fh,$offset,$length, $callback->($retval)	526	=item aio_readahead $fh,$offset,$length, $callback->($retval)
460		527
461	C<aio_readahead> populates the page cache with data from a file so that	528	C<aio_readahead> populates the page cache with data from a file so that
…		…
465	whole pages, so that offset is effectively rounded down to a page boundary	532	whole pages, so that offset is effectively rounded down to a page boundary
466	and bytes are read up to the next page boundary greater than or equal to	533	and bytes are read up to the next page boundary greater than or equal to
467	(off-set+length). C<aio_readahead> does not read beyond the end of the	534	(off-set+length). C<aio_readahead> does not read beyond the end of the
468	file. The current file offset of the file is left unchanged.	535	file. The current file offset of the file is left unchanged.
469		536
470	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	537	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
471	emulated by simply reading the data, which would have a similar effect.	538	be emulated by simply reading the data, which would have a similar effect.
472		539
473		540
474	=item aio_stat $fh_or_path, $callback->($status)	541	=item aio_stat $fh_or_path, $callback->($status)
475		542
476	=item aio_lstat $fh, $callback->($status)	543	=item aio_lstat $fh, $callback->($status)
…		…
545	namemax => 255,	612	namemax => 255,
546	frsize => 1024,	613	frsize => 1024,
547	fsid => 1810	614	fsid => 1810
548	}	615	}
549		616
550
551	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	617	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
552		618
553	Works like perl's C<utime> function (including the special case of $atime	619	Works like perl's C<utime> function (including the special case of $atime
554	and $mtime being undef). Fractional times are supported if the underlying	620	and $mtime being undef). Fractional times are supported if the underlying
555	syscalls support them.	621	syscalls support them.
…		…
582	=item aio_truncate $fh_or_path, $offset, $callback->($status)	648	=item aio_truncate $fh_or_path, $offset, $callback->($status)
583		649
584	Works like truncate(2) or ftruncate(2).	650	Works like truncate(2) or ftruncate(2).
585		651
586		652
		653	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		654
		655	Allocates or frees disk space according to the C<$mode> argument. See the
		656	linux C<fallocate> documentation for details.
		657
		658	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		659	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		660	to deallocate a file range.
		661
		662	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		663	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		664	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		665	to unshare shared blocks (see your L<fallocate(2)> manpage).
		666
		667	The file system block size used by C<fallocate> is presumably the
		668	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		669	can dictate other limitations.
		670
		671	If C<fallocate> isn't available or cannot be emulated (currently no
		672	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		673
		674
587	=item aio_chmod $fh_or_path, $mode, $callback->($status)	675	=item aio_chmod $fh_or_path, $mode, $callback->($status)
588		676
589	Works like perl's C<chmod> function.	677	Works like perl's C<chmod> function.
590		678
591		679
…		…
593		681
594	Asynchronously unlink (delete) a file and call the callback with the	682	Asynchronously unlink (delete) a file and call the callback with the
595	result code.	683	result code.
596		684
597		685
598	=item aio_mknod $path, $mode, $dev, $callback->($status)	686	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
599		687
600	[EXPERIMENTAL]	688	[EXPERIMENTAL]
601		689
602	Asynchronously create a device node (or fifo). See mknod(2).	690	Asynchronously create a device node (or fifo). See mknod(2).
603		691
604	The only (POSIX-) portable way of calling this function is:	692	The only (POSIX-) portable way of calling this function is:
605		693
606	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	694	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
607		695
608	See C<aio_stat> for info about some potentially helpful extra constants	696	See C<aio_stat> for info about some potentially helpful extra constants
609	and functions.	697	and functions.
610		698
611	=item aio_link $srcpath, $dstpath, $callback->($status)	699	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
618		706
619	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	707	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
620	the path C<$dstpath> and call the callback with the result code.	708	the path C<$dstpath> and call the callback with the result code.
621		709
622		710
623	=item aio_readlink $path, $callback->($link)	711	=item aio_readlink $pathname, $callback->($link)
624		712
625	Asynchronously read the symlink specified by C<$path> and pass it to	713	Asynchronously read the symlink specified by C<$path> and pass it to
626	the callback. If an error occurs, nothing or undef gets passed to the	714	the callback. If an error occurs, nothing or undef gets passed to the
627	callback.	715	callback.
628		716
629		717
		718	=item aio_realpath $pathname, $callback->($path)
		719
		720	Asynchronously make the path absolute and resolve any symlinks in
		721	C<$path>. The resulting path only consists of directories (same as
		722	L<Cwd::realpath>).
		723
		724	This request can be used to get the absolute path of the current working
		725	directory by passing it a path of F<.> (a single dot).
		726
		727
630	=item aio_rename $srcpath, $dstpath, $callback->($status)	728	=item aio_rename $srcpath, $dstpath, $callback->($status)
631		729
632	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	730	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
633	rename(2) and call the callback with the result code.	731	rename(2) and call the callback with the result code.
		732
		733	On systems that support the AIO::WD working directory abstraction
		734	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		735	of failing, C<rename> is called on the absolute path of C<$wd>.
		736
		737
		738	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		739
		740	Basically a version of C<aio_rename> with an additional C<$flags>
		741	argument. Calling this with C<$flags=0> is the same as calling
		742	C<aio_rename>.
		743
		744	Non-zero flags are currently only supported on GNU/Linux systems that
		745	support renameat2. Other systems fail with C<ENOSYS> in this case.
		746
		747	The following constants are available (missing ones are, as usual C<0>),
		748	see renameat2(2) for details:
		749
		750	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		751	and C<IO::AIO::RENAME_WHITEOUT>.
634		752
635		753
636	=item aio_mkdir $pathname, $mode, $callback->($status)	754	=item aio_mkdir $pathname, $mode, $callback->($status)
637		755
638	Asynchronously mkdir (create) a directory and call the callback with	756	Asynchronously mkdir (create) a directory and call the callback with
…		…
643	=item aio_rmdir $pathname, $callback->($status)	761	=item aio_rmdir $pathname, $callback->($status)
644		762
645	Asynchronously rmdir (delete) a directory and call the callback with the	763	Asynchronously rmdir (delete) a directory and call the callback with the
646	result code.	764	result code.
647		765
		766	On systems that support the AIO::WD working directory abstraction
		767	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		768	C<rmdir> is called on the absolute path of C<$wd>.
		769
648		770
649	=item aio_readdir $pathname, $callback->($entries)	771	=item aio_readdir $pathname, $callback->($entries)
650		772
651	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	773	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
652	directory (i.e. opendir + readdir + closedir). The entries will not be	774	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
656	array-ref with the filenames.	778	array-ref with the filenames.
657		779
658		780
659	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	781	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
660		782
661	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	783	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
662	behaviour and output format. In case of an error, C<$entries> will be	784	tune behaviour and output format. In case of an error, C<$entries> will be
663	C<undef>.	785	C<undef>.
664		786
665	The flags are a combination of the following constants, ORed together (the	787	The flags are a combination of the following constants, ORed together (the
666	flags will also be passed to the callback, possibly modified):	788	flags will also be passed to the callback, possibly modified):
667		789
668	=over 4	790	=over 4
669		791
670	=item IO::AIO::READDIR_DENTS	792	=item IO::AIO::READDIR_DENTS
671		793
672	When this flag is off, then the callback gets an arrayref with of names	794	When this flag is off, then the callback gets an arrayref consisting of
673	only (as with C<aio_readdir>), otherwise it gets an arrayref with	795	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
674	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	796	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
675	entry in more detail.	797	entry in more detail.
676		798
677	C<$name> is the name of the entry.	799	C<$name> is the name of the entry.
678		800
…		…
691	systems that do not deliver the inode information.	813	systems that do not deliver the inode information.
692		814
693	=item IO::AIO::READDIR_DIRS_FIRST	815	=item IO::AIO::READDIR_DIRS_FIRST
694		816
695	When this flag is set, then the names will be returned in an order where	817	When this flag is set, then the names will be returned in an order where
696	likely directories come first. This is useful when you need to quickly	818	likely directories come first, in optimal stat order. This is useful when
697	find directories, or you want to find all directories while avoiding to	819	you need to quickly find directories, or you want to find all directories
698	stat() each entry.	820	while avoiding to stat() each entry.
699		821
700	If the system returns type information in readdir, then this is used	822	If the system returns type information in readdir, then this is used
701	to find directories directly. Otherwise, likely directories are files	823	to find directories directly. Otherwise, likely directories are names
702	beginning with ".", or otherwise files with no dots, of which files with	824	beginning with ".", or otherwise names with no dots, of which names with
703	short names are tried first.	825	short names are tried first.
704		826
705	=item IO::AIO::READDIR_STAT_ORDER	827	=item IO::AIO::READDIR_STAT_ORDER
706		828
707	When this flag is set, then the names will be returned in an order	829	When this flag is set, then the names will be returned in an order
…		…
714		836
715	=item IO::AIO::READDIR_FOUND_UNKNOWN	837	=item IO::AIO::READDIR_FOUND_UNKNOWN
716		838
717	This flag should not be set when calling C<aio_readdirx>. Instead, it	839	This flag should not be set when calling C<aio_readdirx>. Instead, it
718	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	840	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
719	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	841	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
720	C<$type>'s are known, which can be used to speed up some algorithms.	842	C<$type>'s are known, which can be used to speed up some algorithms.
721		843
722	=back	844	=back
723		845
724		846
		847	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		848
		849	Opens, reads and closes the given file. The data is put into C<$data>,
		850	which is resized as required.
		851
		852	If C<$offset> is negative, then it is counted from the end of the file.
		853
		854	If C<$length> is zero, then the remaining length of the file is
		855	used. Also, in this case, the same limitations to modifying C<$data> apply
		856	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		857	with C<substr>. If the size of the file is known, specifying a non-zero
		858	C<$length> results in a performance advantage.
		859
		860	This request is similar to the older C<aio_load> request, but since it is
		861	a single request, it might be more efficient to use.
		862
		863	Example: load F</etc/passwd> into C<$passwd>.
		864
		865	my $passwd;
		866	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		867	$_[0] >= 0
		868	or die "/etc/passwd: $!\n";
		869
		870	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		871	print $passwd;
		872	};
		873	IO::AIO::flush;
		874
		875
725	=item aio_load $path, $data, $callback->($status)	876	=item aio_load $pathname, $data, $callback->($status)
726		877
727	This is a composite request that tries to fully load the given file into	878	This is a composite request that tries to fully load the given file into
728	memory. Status is the same as with aio_read.	879	memory. Status is the same as with aio_read.
		880
		881	Using C<aio_slurp> might be more efficient, as it is a single request.
729		882
730	=cut	883	=cut
731		884
732	sub aio_load($$;$) {	885	sub aio_load($$;$) {
733	my ($path, undef, $cb) = @_;	886	my ($path, undef, $cb) = @_;
…		…
753	=item aio_copy $srcpath, $dstpath, $callback->($status)	906	=item aio_copy $srcpath, $dstpath, $callback->($status)
754		907
755	Try to copy the I<file> (directories not supported as either source or	908	Try to copy the I<file> (directories not supported as either source or
756	destination) from C<$srcpath> to C<$dstpath> and call the callback with	909	destination) from C<$srcpath> to C<$dstpath> and call the callback with
757	a status of C<0> (ok) or C<-1> (error, see C<$!>).	910	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		911
		912	Existing destination files will be truncated.
758		913
759	This is a composite request that creates the destination file with	914	This is a composite request that creates the destination file with
760	mode 0200 and copies the contents of the source file into it using	915	mode 0200 and copies the contents of the source file into it using
761	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	916	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
762	uid/gid, in that order.	917	uid/gid, in that order.
…		…
852	if ($_[0] && $! == EXDEV) {	1007	if ($_[0] && $! == EXDEV) {
853	aioreq_pri $pri;	1008	aioreq_pri $pri;
854	add $grp aio_copy $src, $dst, sub {	1009	add $grp aio_copy $src, $dst, sub {
855	$grp->result ($_[0]);	1010	$grp->result ($_[0]);
856		1011
857	if (!$_[0]) {	1012	unless ($_[0]) {
858	aioreq_pri $pri;	1013	aioreq_pri $pri;
859	add $grp aio_unlink $src;	1014	add $grp aio_unlink $src;
860	}	1015	}
861	};	1016	};
862	} else {	1017	} else {
…		…
865	};	1020	};
866		1021
867	$grp	1022	$grp
868	}	1023	}
869		1024
870	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1025	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
871		1026
872	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1027	Scans a directory (similar to C<aio_readdir>) but additionally tries to
873	efficiently separate the entries of directory C<$path> into two sets of	1028	efficiently separate the entries of directory C<$path> into two sets of
874	names, directories you can recurse into (directories), and ones you cannot	1029	names, directories you can recurse into (directories), and ones you cannot
875	recurse into (everything else, including symlinks to directories).	1030	recurse into (everything else, including symlinks to directories).
876		1031
877	C<aio_scandir> is a composite request that creates of many sub requests_	1032	C<aio_scandir> is a composite request that generates many sub requests.
878	C<$maxreq> specifies the maximum number of outstanding aio requests that	1033	C<$maxreq> specifies the maximum number of outstanding aio requests that
879	this function generates. If it is C<< <= 0 >>, then a suitable default	1034	this function generates. If it is C<< <= 0 >>, then a suitable default
880	will be chosen (currently 4).	1035	will be chosen (currently 4).
881		1036
882	On error, the callback is called without arguments, otherwise it receives	1037	On error, the callback is called without arguments, otherwise it receives
…		…
906	Then entries will be sorted into likely directories a non-initial dot	1061	Then entries will be sorted into likely directories a non-initial dot
907	currently) and likely non-directories (see C<aio_readdirx>). Then every	1062	currently) and likely non-directories (see C<aio_readdirx>). Then every
908	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1063	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
909	in order of their inode numbers. If that succeeds, it assumes that the	1064	in order of their inode numbers. If that succeeds, it assumes that the
910	entry is a directory or a symlink to directory (which will be checked	1065	entry is a directory or a symlink to directory (which will be checked
911	seperately). This is often faster than stat'ing the entry itself because	1066	separately). This is often faster than stat'ing the entry itself because
912	filesystems might detect the type of the entry without reading the inode	1067	filesystems might detect the type of the entry without reading the inode
913	data (e.g. ext2fs filetype feature), even on systems that cannot return	1068	data (e.g. ext2fs filetype feature), even on systems that cannot return
914	the filetype information on readdir.	1069	the filetype information on readdir.
915		1070
916	If the known number of directories (link count - 2) has been reached, the	1071	If the known number of directories (link count - 2) has been reached, the
…		…
932		1087
933	my $grp = aio_group $cb;	1088	my $grp = aio_group $cb;
934		1089
935	$maxreq = 4 if $maxreq <= 0;	1090	$maxreq = 4 if $maxreq <= 0;
936		1091
937	# stat once	1092	# get a wd object
938	aioreq_pri $pri;	1093	aioreq_pri $pri;
939	add $grp aio_stat $path, sub {	1094	add $grp aio_wd $path, sub {
		1095	$_[0]
940	return $grp->result () if $_[0];	1096	or return $grp->result ();
941	my $now = time;
942	my $hash1 = join ":", (stat _)[0,1,3,7,9];
943		1097
944	# read the directory entries	1098	my $wd = [shift, "."];
		1099
		1100	# stat once
945	aioreq_pri $pri;	1101	aioreq_pri $pri;
946	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1102	add $grp aio_stat $wd, sub {
947	my $entries = shift
948	or return $grp->result ();	1103	return $grp->result () if $_[0];
		1104	my $now = time;
		1105	my $hash1 = join ":", (stat _)[0,1,3,7,9];
949		1106
950	# stat the dir another time	1107	# read the directory entries
951	aioreq_pri $pri;	1108	aioreq_pri $pri;
		1109	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1110	my $entries = shift
		1111	or return $grp->result ();
		1112
		1113	# stat the dir another time
		1114	aioreq_pri $pri;
952	add $grp aio_stat $path, sub {	1115	add $grp aio_stat $wd, sub {
953	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1116	my $hash2 = join ":", (stat _)[0,1,3,7,9];
954		1117
955	my $ndirs;	1118	my $ndirs;
956		1119
957	# take the slow route if anything looks fishy	1120	# take the slow route if anything looks fishy
958	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1121	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
959	$ndirs = -1;	1122	$ndirs = -1;
960	} else {	1123	} else {
961	# if nlink == 2, we are finished	1124	# if nlink == 2, we are finished
962	# for non-posix-fs's, we rely on nlink < 2	1125	# for non-posix-fs's, we rely on nlink < 2
963	$ndirs = (stat _)[3] - 2	1126	$ndirs = (stat _)[3] - 2
964	or return $grp->result ([], $entries);	1127	or return $grp->result ([], $entries);
965	}	1128	}
966		1129
967	my (@dirs, @nondirs);	1130	my (@dirs, @nondirs);
968		1131
969	my $statgrp = add $grp aio_group sub {	1132	my $statgrp = add $grp aio_group sub {
970	$grp->result (\@dirs, \@nondirs);	1133	$grp->result (\@dirs, \@nondirs);
971	};	1134	};
972		1135
973	limit $statgrp $maxreq;	1136	limit $statgrp $maxreq;
974	feed $statgrp sub {	1137	feed $statgrp sub {
975	return unless @$entries;	1138	return unless @$entries;
976	my $entry = shift @$entries;	1139	my $entry = shift @$entries;
977		1140
978	aioreq_pri $pri;	1141	aioreq_pri $pri;
		1142	$wd->[1] = "$entry/.";
979	add $statgrp aio_stat "$path/$entry/.", sub {	1143	add $statgrp aio_stat $wd, sub {
980	if ($_[0] < 0) {	1144	if ($_[0] < 0) {
981	push @nondirs, $entry;	1145	push @nondirs, $entry;
982	} else {	1146	} else {
983	# need to check for real directory	1147	# need to check for real directory
984	aioreq_pri $pri;	1148	aioreq_pri $pri;
		1149	$wd->[1] = $entry;
985	add $statgrp aio_lstat "$path/$entry", sub {	1150	add $statgrp aio_lstat $wd, sub {
986	if (-d _) {	1151	if (-d _) {
987	push @dirs, $entry;	1152	push @dirs, $entry;
988		1153
989	unless (--$ndirs) {	1154	unless (--$ndirs) {
990	push @nondirs, @$entries;	1155	push @nondirs, @$entries;
991	feed $statgrp;	1156	feed $statgrp;
		1157	}
		1158	} else {
		1159	push @nondirs, $entry;
992	}	1160	}
993	} else {
994	push @nondirs, $entry;
995	}	1161	}
996	}	1162	}
997	}	1163	};
998	};	1164	};
999	};	1165	};
1000	};	1166	};
1001	};	1167	};
1002	};	1168	};
1003		1169
1004	$grp	1170	$grp
1005	}	1171	}
1006		1172
1007	=item aio_rmtree $path, $callback->($status)	1173	=item aio_rmtree $pathname, $callback->($status)
1008		1174
1009	Delete a directory tree starting (and including) C<$path>, return the	1175	Delete a directory tree starting (and including) C<$path>, return the
1010	status of the final C<rmdir> only. This is a composite request that	1176	status of the final C<rmdir> only. This is a composite request that
1011	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1177	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1012	everything else.	1178	everything else.
1013		1179
1014	=cut	1180	=cut
1015		1181
…		…
1037	};	1203	};
1038		1204
1039	$grp	1205	$grp
1040	}	1206	}
1041		1207
		1208	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1209
		1210	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1211
		1212	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1213	they execute asynchronously and pass the return value to the callback.
		1214
		1215	Both calls can be used for a lot of things, some of which make more sense
		1216	to run asynchronously in their own thread, while some others make less
		1217	sense. For example, calls that block waiting for external events, such
		1218	as locking, will also lock down an I/O thread while it is waiting, which
		1219	can deadlock the whole I/O system. At the same time, there might be no
		1220	alternative to using a thread to wait.
		1221
		1222	So in general, you should only use these calls for things that do
		1223	(filesystem) I/O, not for things that wait for other events (network,
		1224	other processes), although if you are careful and know what you are doing,
		1225	you still can.
		1226
		1227	The following constants are available (missing ones are, as usual C<0>):
		1228
		1229	C<F_DUPFD_CLOEXEC>,
		1230
		1231	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1232
		1233	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1234
		1235	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1236	C<FS_IOC_FIEMAP>.
		1237
		1238	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1239	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1240
		1241	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1242	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1243	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1244	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1245	C<FS_FL_USER_MODIFIABLE>.
		1246
		1247	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1248	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1249	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1250	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1251
1042	=item aio_sync $callback->($status)	1252	=item aio_sync $callback->($status)
1043		1253
1044	Asynchronously call sync and call the callback when finished.	1254	Asynchronously call sync and call the callback when finished.
1045		1255
1046	=item aio_fsync $fh, $callback->($status)	1256	=item aio_fsync $fh, $callback->($status)
…		…
1053	Asynchronously call fdatasync on the given filehandle and call the	1263	Asynchronously call fdatasync on the given filehandle and call the
1054	callback with the fdatasync result code.	1264	callback with the fdatasync result code.
1055		1265
1056	If this call isn't available because your OS lacks it or it couldn't be	1266	If this call isn't available because your OS lacks it or it couldn't be
1057	detected, it will be emulated by calling C<fsync> instead.	1267	detected, it will be emulated by calling C<fsync> instead.
		1268
		1269	=item aio_syncfs $fh, $callback->($status)
		1270
		1271	Asynchronously call the syncfs syscall to sync the filesystem associated
		1272	to the given filehandle and call the callback with the syncfs result
		1273	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1274	errno to C<ENOSYS> nevertheless.
1058		1275
1059	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1276	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1060		1277
1061	Sync the data portion of the file specified by C<$offset> and C<$length>	1278	Sync the data portion of the file specified by C<$offset> and C<$length>
1062	to disk (but NOT the metadata), by calling the Linux-specific	1279	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1066	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1283	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1067	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1284	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1068	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1285	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1069	manpage for details.	1286	manpage for details.
1070		1287
1071	=item aio_pathsync $path, $callback->($status)	1288	=item aio_pathsync $pathname, $callback->($status)
1072		1289
1073	This request tries to open, fsync and close the given path. This is a	1290	This request tries to open, fsync and close the given path. This is a
1074	composite request intended to sync directories after directory operations	1291	composite request intended to sync directories after directory operations
1075	(E.g. rename). This might not work on all operating systems or have any	1292	(E.g. rename). This might not work on all operating systems or have any
1076	specific effect, but usually it makes sure that directory changes get	1293	specific effect, but usually it makes sure that directory changes get
…		…
1107	};	1324	};
1108		1325
1109	$grp	1326	$grp
1110	}	1327	}
1111		1328
1112	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1329	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1113		1330
1114	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1331	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1115	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1332	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1116	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1333	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1117	scalar must only be modified in-place while an aio operation is pending on	1334	scalar must only be modified in-place while an aio operation is pending on
…		…
1119		1336
1120	It calls the C<msync> function of your OS, if available, with the memory	1337	It calls the C<msync> function of your OS, if available, with the memory
1121	area starting at C<$offset> in the string and ending C<$length> bytes	1338	area starting at C<$offset> in the string and ending C<$length> bytes
1122	later. If C<$length> is negative, counts from the end, and if C<$length>	1339	later. If C<$length> is negative, counts from the end, and if C<$length>
1123	is C<undef>, then it goes till the end of the string. The flags can be	1340	is C<undef>, then it goes till the end of the string. The flags can be
1124	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1341	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1125	C<IO::AIO::MS_SYNC>.	1342	C<IO::AIO::MS_INVALIDATE>.
1126		1343
1127	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1344	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1128		1345
1129	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1346	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1130	scalars.	1347	scalars.
1131		1348
1132	It touches (reads or writes) all memory pages in the specified	1349	It touches (reads or writes) all memory pages in the specified
1133	range inside the scalar. All caveats and parameters are the same	1350	range inside the scalar. All caveats and parameters are the same
1134	as for C<aio_msync>, above, except for flags, which must be either	1351	as for C<aio_msync>, above, except for flags, which must be either
1135	C<0> (which reads all pages and ensures they are instantiated) or	1352	C<0> (which reads all pages and ensures they are instantiated) or
1136	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1353	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1137	writing an octet from it, which dirties the page).	1354	writing an octet from it, which dirties the page).
1138		1355
1139	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1356	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1140		1357
1141	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1358	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1172	documented under L<MISCELLANEOUS FUNCTIONS>.	1389	documented under L<MISCELLANEOUS FUNCTIONS>.
1173		1390
1174	Example: asynchronously lock all current and future pages into memory.	1391	Example: asynchronously lock all current and future pages into memory.
1175		1392
1176	aio_mlockall IO::AIO::MCL_FUTURE;	1393	aio_mlockall IO::AIO::MCL_FUTURE;
		1394
		1395	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1396
		1397	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1398	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1399	the ioctl is not available on your OS, then this request will fail with
		1400	C<ENOSYS>.
		1401
		1402	C<$start> is the starting offset to query extents for, C<$length> is the
		1403	size of the range to query - if it is C<undef>, then the whole file will
		1404	be queried.
		1405
		1406	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1407	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1408	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1409	the data portion.
		1410
		1411	C<$count> is the maximum number of extent records to return. If it is
		1412	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1413	case, if it is C<0>, then the callback receives the number of extents
		1414	instead of the extents themselves (which is unreliable, see below).
		1415
		1416	If an error occurs, the callback receives no arguments. The special
		1417	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1418
		1419	Otherwise, the callback receives an array reference with extent
		1420	structures. Each extent structure is an array reference itself, with the
		1421	following members:
		1422
		1423	[$logical, $physical, $length, $flags]
		1424
		1425	Flags is any combination of the following flag values (typically either C<0>
		1426	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1427
		1428	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1429	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1430	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1431	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1432	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1433	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1434
		1435	At the time of this writing (Linux 3.2), this request is unreliable unless
		1436	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1437	it to return all extents of a range for files with a large number of
		1438	extents. The code (only) works around all these issues if C<$count> is
		1439	C<undef>.
1177		1440
1178	=item aio_group $callback->(...)	1441	=item aio_group $callback->(...)
1179		1442
1180	This is a very special aio request: Instead of doing something, it is a	1443	This is a very special aio request: Instead of doing something, it is a
1181	container for other aio requests, which is useful if you want to bundle	1444	container for other aio requests, which is useful if you want to bundle
…		…
1218	like sleep and file handle readable/writable, the overhead this creates is	1481	like sleep and file handle readable/writable, the overhead this creates is
1219	immense (it blocks a thread for a long time) so do not use this function	1482	immense (it blocks a thread for a long time) so do not use this function
1220	except to put your application under artificial I/O pressure.	1483	except to put your application under artificial I/O pressure.
1221		1484
1222	=back	1485	=back
		1486
		1487
		1488	=head2 IO::AIO::WD - multiple working directories
		1489
		1490	Your process only has one current working directory, which is used by all
		1491	threads. This makes it hard to use relative paths (some other component
		1492	could call C<chdir> at any time, and it is hard to control when the path
		1493	will be used by IO::AIO).
		1494
		1495	One solution for this is to always use absolute paths. This usually works,
		1496	but can be quite slow (the kernel has to walk the whole path on every
		1497	access), and can also be a hassle to implement.
		1498
		1499	Newer POSIX systems have a number of functions (openat, fdopendir,
		1500	futimensat and so on) that make it possible to specify working directories
		1501	per operation.
		1502
		1503	For portability, and because the clowns who "designed", or shall I write,
		1504	perpetrated this new interface were obviously half-drunk, this abstraction
		1505	cannot be perfect, though.
		1506
		1507	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1508	object. This object stores the canonicalised, absolute version of the
		1509	path, and on systems that allow it, also a directory file descriptor.
		1510
		1511	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1512	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1513	object and a pathname instead (or the IO::AIO::WD object alone, which
		1514	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1515	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1516	to that IO::AIO::WD object.
		1517
		1518	For example, to get a wd object for F</etc> and then stat F<passwd>
		1519	inside, you would write:
		1520
		1521	aio_wd "/etc", sub {
		1522	my $etcdir = shift;
		1523
		1524	# although $etcdir can be undef on error, there is generally no reason
		1525	# to check for errors here, as aio_stat will fail with ENOENT
		1526	# when $etcdir is undef.
		1527
		1528	aio_stat [$etcdir, "passwd"], sub {
		1529	# yay
		1530	};
		1531	};
		1532
		1533	The fact that C<aio_wd> is a request and not a normal function shows that
		1534	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1535	which is why it is done asynchronously.
		1536
		1537	To stat the directory obtained with C<aio_wd> above, one could write
		1538	either of the following three request calls:
		1539
		1540	aio_lstat "/etc" , sub { ... # pathname as normal string
		1541	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1542	aio_lstat $wd , sub { ... # shorthand for the previous
		1543
		1544	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1545	object and the pathname string, so you could write the following without
		1546	causing any issues due to C<$path> getting reused:
		1547
		1548	my $path = [$wd, undef];
		1549
		1550	for my $name (qw(abc def ghi)) {
		1551	$path->[1] = $name;
		1552	aio_stat $path, sub {
		1553	# ...
		1554	};
		1555	}
		1556
		1557	There are some caveats: when directories get renamed (or deleted), the
		1558	pathname string doesn't change, so will point to the new directory (or
		1559	nowhere at all), while the directory fd, if available on the system,
		1560	will still point to the original directory. Most functions accepting a
		1561	pathname will use the directory fd on newer systems, and the string on
		1562	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1563	the string form of the pathname.
		1564
		1565	So this functionality is mainly useful to get some protection against
		1566	C<chdir>, to easily get an absolute path out of a relative path for future
		1567	reference, and to speed up doing many operations in the same directory
		1568	(e.g. when stat'ing all files in a directory).
		1569
		1570	The following functions implement this working directory abstraction:
		1571
		1572	=over 4
		1573
		1574	=item aio_wd $pathname, $callback->($wd)
		1575
		1576	Asynchonously canonicalise the given pathname and convert it to an
		1577	IO::AIO::WD object representing it. If possible and supported on the
		1578	system, also open a directory fd to speed up pathname resolution relative
		1579	to this working directory.
		1580
		1581	If something goes wrong, then C<undef> is passwd to the callback instead
		1582	of a working directory object and C<$!> is set appropriately. Since
		1583	passing C<undef> as working directory component of a pathname fails the
		1584	request with C<ENOENT>, there is often no need for error checking in the
		1585	C<aio_wd> callback, as future requests using the value will fail in the
		1586	expected way.
		1587
		1588	=item IO::AIO::CWD
		1589
		1590	This is a compiletime constant (object) that represents the process
		1591	current working directory.
		1592
		1593	Specifying this object as working directory object for a pathname is as if
		1594	the pathname would be specified directly, without a directory object. For
		1595	example, these calls are functionally identical:
		1596
		1597	aio_stat "somefile", sub { ... };
		1598	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1599
		1600	=back
		1601
		1602	To recover the path associated with an IO::AIO::WD object, you can use
		1603	C<aio_realpath>:
		1604
		1605	aio_realpath $wd, sub {
		1606	warn "path is $_[0]\n";
		1607	};
		1608
		1609	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1610	sometimes, fall back to using an absolue path.
1223		1611
1224	=head2 IO::AIO::REQ CLASS	1612	=head2 IO::AIO::REQ CLASS
1225		1613
1226	All non-aggregate C<aio_*> functions return an object of this class when	1614	All non-aggregate C<aio_*> functions return an object of this class when
1227	called in non-void context.	1615	called in non-void context.
…		…
1345		1733
1346	Sets a feeder/generator on this group: every group can have an attached	1734	Sets a feeder/generator on this group: every group can have an attached
1347	generator that generates requests if idle. The idea behind this is that,	1735	generator that generates requests if idle. The idea behind this is that,
1348	although you could just queue as many requests as you want in a group,	1736	although you could just queue as many requests as you want in a group,
1349	this might starve other requests for a potentially long time. For example,	1737	this might starve other requests for a potentially long time. For example,
1350	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1738	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1351	delaying any later requests for a long time.	1739	requests, delaying any later requests for a long time.
1352		1740
1353	To avoid this, and allow incremental generation of requests, you can	1741	To avoid this, and allow incremental generation of requests, you can
1354	instead a group and set a feeder on it that generates those requests. The	1742	instead a group and set a feeder on it that generates those requests. The
1355	feed callback will be called whenever there are few enough (see C<limit>,	1743	feed callback will be called whenever there are few enough (see C<limit>,
1356	below) requests active in the group itself and is expected to queue more	1744	below) requests active in the group itself and is expected to queue more
…		…
1405		1793
1406	See C<poll_cb> for an example.	1794	See C<poll_cb> for an example.
1407		1795
1408	=item IO::AIO::poll_cb	1796	=item IO::AIO::poll_cb
1409		1797
1410	Process some outstanding events on the result pipe. You have to call this	1798	Process some requests that have reached the result phase (i.e. they have
1411	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1799	been executed but the results are not yet reported). You have to call
1412	returned earlier for whatever reason. Returns immediately when no events	1800	this "regularly" to finish outstanding requests.
1413	are outstanding. The amount of events processed depends on the settings of
1414	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1415		1801
		1802	Returns C<0> if all events could be processed (or there were no
		1803	events to process), or C<-1> if it returned earlier for whatever
		1804	reason. Returns immediately when no events are outstanding. The amount
		1805	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1806	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1807
1416	If not all requests were processed for whatever reason, the filehandle	1808	If not all requests were processed for whatever reason, the poll file
1417	will still be ready when C<poll_cb> returns, so normally you don't have to	1809	descriptor will still be ready when C<poll_cb> returns, so normally you
1418	do anything special to have it called later.	1810	don't have to do anything special to have it called later.
		1811
		1812	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1813	ready, it can be beneficial to call this function from loops which submit
		1814	a lot of requests, to make sure the results get processed when they become
		1815	available and not just when the loop is finished and the event loop takes
		1816	over again. This function returns very fast when there are no outstanding
		1817	requests.
1419		1818
1420	Example: Install an Event watcher that automatically calls	1819	Example: Install an Event watcher that automatically calls
1421	IO::AIO::poll_cb with high priority (more examples can be found in the	1820	IO::AIO::poll_cb with high priority (more examples can be found in the
1422	SYNOPSIS section, at the top of this document):	1821	SYNOPSIS section, at the top of this document):
1423		1822
…		…
1425	poll => 'r', async => 1,	1824	poll => 'r', async => 1,
1426	cb => \&IO::AIO::poll_cb);	1825	cb => \&IO::AIO::poll_cb);
1427		1826
1428	=item IO::AIO::poll_wait	1827	=item IO::AIO::poll_wait
1429		1828
1430	If there are any outstanding requests and none of them in the result	1829	Wait until either at least one request is in the result phase or no
1431	phase, wait till the result filehandle becomes ready for reading (simply	1830	requests are outstanding anymore.
1432	does a C<select> on the filehandle. This is useful if you want to	1831
1433	synchronously wait for some requests to finish).	1832	This is useful if you want to synchronously wait for some requests to
		1833	become ready, without actually handling them.
1434		1834
1435	See C<nreqs> for an example.	1835	See C<nreqs> for an example.
1436		1836
1437	=item IO::AIO::poll	1837	=item IO::AIO::poll
1438		1838
…		…
1525		1925
1526	Under normal circumstances you don't need to call this function.	1926	Under normal circumstances you don't need to call this function.
1527		1927
1528	=item IO::AIO::max_idle $nthreads	1928	=item IO::AIO::max_idle $nthreads
1529		1929
1530	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1930	Limit the number of threads (default: 4) that are allowed to idle
1531	threads that did not get a request to process within 10 seconds). That	1931	(i.e., threads that did not get a request to process within the idle
1532	means if a thread becomes idle while C<$nthreads> other threads are also	1932	timeout (default: 10 seconds). That means if a thread becomes idle while
1533	idle, it will free its resources and exit.	1933	C<$nthreads> other threads are also idle, it will free its resources and
		1934	exit.
1534		1935
1535	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1936	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1536	to allow for extremely high load situations, but want to free resources	1937	to allow for extremely high load situations, but want to free resources
1537	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1938	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1538		1939
1539	The default is probably ok in most situations, especially if thread	1940	The default is probably ok in most situations, especially if thread
1540	creation is fast. If thread creation is very slow on your system you might	1941	creation is fast. If thread creation is very slow on your system you might
1541	want to use larger values.	1942	want to use larger values.
1542		1943
		1944	=item IO::AIO::idle_timeout $seconds
		1945
		1946	Sets the minimum idle timeout (default 10) after which worker threads are
		1947	allowed to exit. SEe C<IO::AIO::max_idle>.
		1948
1543	=item IO::AIO::max_outstanding $maxreqs	1949	=item IO::AIO::max_outstanding $maxreqs
		1950
		1951	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1952	you do queue up more than this number of requests, the next call to
		1953	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1954	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1955	longer exceeded.
		1956
		1957	In other words, this setting does not enforce a queue limit, but can be
		1958	used to make poll functions block if the limit is exceeded.
1544		1959
1545	This is a very bad function to use in interactive programs because it	1960	This is a very bad function to use in interactive programs because it
1546	blocks, and a bad way to reduce concurrency because it is inexact: Better	1961	blocks, and a bad way to reduce concurrency because it is inexact: Better
1547	use an C<aio_group> together with a feed callback.	1962	use an C<aio_group> together with a feed callback.
1548		1963
1549	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1964	Its main use is in scripts without an event loop - when you want to stat
1550	do queue up more than this number of requests, the next call to the	1965	a lot of files, you can write something like this:
1551	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1552	function will block until the limit is no longer exceeded.
1553		1966
1554	The default value is very large, so there is no practical limit on the	1967	IO::AIO::max_outstanding 32;
1555	number of outstanding requests.
1556		1968
1557	You can still queue as many requests as you want. Therefore,	1969	for my $path (...) {
1558	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1970	aio_stat $path , ...;
1559	as a stop gap to shield against fatal memory overflow (with large values).	1971	IO::AIO::poll_cb;
		1972	}
		1973
		1974	IO::AIO::flush;
		1975
		1976	The call to C<poll_cb> inside the loop will normally return instantly, but
		1977	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1978	some requests have been handled. This keeps the loop from pushing a large
		1979	number of C<aio_stat> requests onto the queue.
		1980
		1981	The default value for C<max_outstanding> is very large, so there is no
		1982	practical limit on the number of outstanding requests.
1560		1983
1561	=back	1984	=back
1562		1985
1563	=head3 STATISTICAL INFORMATION	1986	=head3 STATISTICAL INFORMATION
1564		1987
…		…
1586		2009
1587	=back	2010	=back
1588		2011
1589	=head3 MISCELLANEOUS FUNCTIONS	2012	=head3 MISCELLANEOUS FUNCTIONS
1590		2013
1591	IO::AIO implements some functions that might be useful, but are not	2014	IO::AIO implements some functions that are useful when you want to use
1592	asynchronous.	2015	some "Advanced I/O" function not available to in Perl, without going the
		2016	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2017	counterpart.
1593		2018
1594	=over 4	2019	=over 4
		2020
		2021	=item $numfd = IO::AIO::get_fdlimit
		2022
		2023	This function is I<EXPERIMENTAL> and subject to change.
		2024
		2025	Tries to find the current file descriptor limit and returns it, or
		2026	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2027	the highest valid file descriptor number.
		2028
		2029	=item IO::AIO::min_fdlimit [$numfd]
		2030
		2031	This function is I<EXPERIMENTAL> and subject to change.
		2032
		2033	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2034	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2035	is missing, it will try to set a very high limit, although this is not
		2036	recommended when you know the actual minimum that you require.
		2037
		2038	If the limit cannot be raised enough, the function makes a best-effort
		2039	attempt to increase the limit as much as possible, using various
		2040	tricks, while still failing. You can query the resulting limit using
		2041	C<IO::AIO::get_fdlimit>.
		2042
		2043	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2044	true.
1595		2045
1596	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2046	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1597		2047
1598	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2048	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1599	but is blocking (this makes most sense if you know the input data is	2049	but is blocking (this makes most sense if you know the input data is
…		…
1604		2054
1605	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2055	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1606		2056
1607	Simply calls the C<posix_fadvise> function (see its	2057	Simply calls the C<posix_fadvise> function (see its
1608	manpage for details). The following advice constants are	2058	manpage for details). The following advice constants are
1609	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2059	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1610	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2060	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1611	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2061	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1612		2062
1613	On systems that do not implement C<posix_fadvise>, this function returns	2063	On systems that do not implement C<posix_fadvise>, this function returns
1614	ENOSYS, otherwise the return value of C<posix_fadvise>.	2064	ENOSYS, otherwise the return value of C<posix_fadvise>.
1615		2065
1616	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2066	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1617		2067
1618	Simply calls the C<posix_madvise> function (see its	2068	Simply calls the C<posix_madvise> function (see its
1619	manpage for details). The following advice constants are	2069	manpage for details). The following advice constants are
1620	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2070	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1621	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2071	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2072	C<IO::AIO::MADV_DONTNEED>.
		2073
		2074	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2075	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2076	will be reduced to fit into the C<$scalar>.
1622		2077
1623	On systems that do not implement C<posix_madvise>, this function returns	2078	On systems that do not implement C<posix_madvise>, this function returns
1624	ENOSYS, otherwise the return value of C<posix_madvise>.	2079	ENOSYS, otherwise the return value of C<posix_madvise>.
1625		2080
1626	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2081	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1627		2082
1628	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2083	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1629	$scalar (see its manpage for details). The following protect	2084	$scalar (see its manpage for details). The following protect
1630	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2085	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1631	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2086	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2087
		2088	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2089	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2090	will be reduced to fit into the C<$scalar>.
1632		2091
1633	On systems that do not implement C<mprotect>, this function returns	2092	On systems that do not implement C<mprotect>, this function returns
1634	ENOSYS, otherwise the return value of C<mprotect>.	2093	ENOSYS, otherwise the return value of C<mprotect>.
1635		2094
1636	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2095	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1637		2096
1638	Memory-maps a file (or anonymous memory range) and attaches it to the	2097	Memory-maps a file (or anonymous memory range) and attaches it to the
1639	given C<$scalar>, which will act like a string scalar.	2098	given C<$scalar>, which will act like a string scalar. Returns true on
		2099	success, and false otherwise.
1640		2100
		2101	The scalar must exist, but its contents do not matter - this means you
		2102	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2103	the scalar first.
		2104
1641	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2105	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1642	change the string length, and most read-only operations such as copying it	2106	which don't change the string length, and most read-only operations such
1643	or searching it with regexes and so on.	2107	as copying it or searching it with regexes and so on.
1644		2108
1645	Anything else is unsafe and will, at best, result in memory leaks.	2109	Anything else is unsafe and will, at best, result in memory leaks.
1646		2110
1647	The memory map associated with the C<$scalar> is automatically removed	2111	The memory map associated with the C<$scalar> is automatically removed
1648	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2112	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1649	C<IO::AIO::munmap> functions are called.	2113	or C<IO::AIO::munmap> functions are called on it.
1650		2114
1651	This calls the C<mmap>(2) function internally. See your system's manual	2115	This calls the C<mmap>(2) function internally. See your system's manual
1652	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2116	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1653		2117
1654	The C<$length> must be larger than zero and smaller than the actual	2118	The C<$length> must be larger than zero and smaller than the actual
1655	filesize.	2119	filesize.
1656		2120
1657	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2121	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1658	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2122	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1659		2123
1660	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2124	C<$flags> can be a combination of
1661	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2125	C<IO::AIO::MAP_SHARED> or
1662	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2126	C<IO::AIO::MAP_PRIVATE>,
		2127	or a number of system-specific flags (when not available, the are C<0>):
1663	(which is set to C<MAP_ANON> if your system only provides this	2128	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1664	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2129	C<IO::AIO::MAP_LOCKED>,
1665	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2130	C<IO::AIO::MAP_NORESERVE>,
		2131	C<IO::AIO::MAP_POPULATE>,
1666	C<IO::AIO::MAP_NONBLOCK>	2132	C<IO::AIO::MAP_NONBLOCK>,
		2133	C<IO::AIO::MAP_FIXED>,
		2134	C<IO::AIO::MAP_GROWSDOWN>,
		2135	C<IO::AIO::MAP_32BIT>,
		2136	C<IO::AIO::MAP_HUGETLB> or
		2137	C<IO::AIO::MAP_STACK>.
1667		2138
1668	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2139	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1669		2140
1670	C<$offset> is the offset from the start of the file - it generally must be	2141	C<$offset> is the offset from the start of the file - it generally must be
1671	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2142	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1696		2167
1697	Calls the C<munlockall> function.	2168	Calls the C<munlockall> function.
1698		2169
1699	On systems that do not implement C<munlockall>, this function returns	2170	On systems that do not implement C<munlockall>, this function returns
1700	ENOSYS, otherwise the return value of C<munlockall>.	2171	ENOSYS, otherwise the return value of C<munlockall>.
		2172
		2173	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2174
		2175	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2176	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2177	should be the file offset.
		2178
		2179	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2180	silently corrupt the data in this case.
		2181
		2182	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2183	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2184	C<IO::AIO::SPLICE_F_GIFT>.
		2185
		2186	See the C<splice(2)> manpage for details.
		2187
		2188	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2189
		2190	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2191	description for C<IO::AIO::splice> above for details.
		2192
		2193	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2194
		2195	Attempts to query or change the pipe buffer size. Obviously works only
		2196	on pipes, and currently works only on GNU/Linux systems, and fails with
		2197	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2198	size on other systems, drop me a note.
		2199
		2200	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2201
		2202	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2203	C<$flags> is missing or C<0>, then this should be the same as a call to
		2204	perl's built-in C<pipe> function and create a new pipe, and works on
		2205	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2206	(..., 4096, O_BINARY)>.
		2207
		2208	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2209	the given flags (Linux 2.6.27, glibc 2.9).
		2210
		2211	On success, the read and write file handles are returned.
		2212
		2213	On error, nothing will be returned. If the pipe2 syscall is missing and
		2214	C<$flags> is non-zero, fails with C<ENOSYS>.
		2215
		2216	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2217	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2218	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2219
		2220	Example: create a pipe race-free w.r.t. threads and fork:
		2221
		2222	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2223	or die "pipe2: $!\n";
		2224
		2225	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2226
		2227	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2228	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2229
		2230	On success, the new eventfd filehandle is returned, otherwise returns
		2231	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2232
		2233	Please refer to L<eventfd(2)> for more info on this call.
		2234
		2235	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2236	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2237
		2238	Example: create a new eventfd filehandle:
		2239
		2240	$fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC
		2241	or die "eventfd: $!\n";
		2242
		2243	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2244
		2245	This is a direct interface to the Linux L<timerfd_create(2)> system call. The
		2246	(unhelpful) default for C<$flags> is C<0>.
		2247
		2248	On success, the new timerfd filehandle is returned, otherwise returns
		2249	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2250
		2251	Please refer to L<timerfd_create(2)> for more info on this call.
		2252
		2253	The following C<$clockid> values are
		2254	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2255	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2256	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2257	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2258
		2259	The following C<$flags> values are available (Linux
		2260	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2261
		2262	Example: create a new timerfd and set it to one-second repeated alarms,
		2263	then wait for two alarms:
		2264
		2265	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2266	or die "timerfd_create: $!\n";
		2267
		2268	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2269	or die "timerfd_settime: $!\n";
		2270
		2271	for (1..2) {
		2272	8 == sysread $fh, my $buf, 8
		2273	or die "timerfd read failure\n";
		2274
		2275	printf "number of expirations (likely 1): %d\n",
		2276	unpack "Q", $buf;
		2277	}
		2278
		2279	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2280
		2281	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2282	call. Please refer to its manpage for more info on this call.
		2283
		2284	The new itimerspec is specified using two (possibly fractional) second
		2285	values, C<$new_interval> and C<$new_value>).
		2286
		2287	On success, the current interval and value are returned (as per
		2288	C<timerfd_gettime>). On failure, the empty list is returned.
		2289
		2290	The following C<$flags> values are
		2291	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2292	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2293
		2294	See C<IO::AIO::timerfd_create> for a full example.
		2295
		2296	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2297
		2298	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2299	call. Please refer to its manpage for more info on this call.
		2300
		2301	On success, returns the current values of interval and value for the given
		2302	timerfd (as potentially fractional second values). On failure, the empty
		2303	list is returned.
1701		2304
1702	=back	2305	=back
1703		2306
1704	=cut	2307	=cut
1705		2308
…		…
1740	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2343	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1741	\&IO::AIO::poll_cb);	2344	\&IO::AIO::poll_cb);
1742		2345
1743	=head2 FORK BEHAVIOUR	2346	=head2 FORK BEHAVIOUR
1744		2347
1745	This module should do "the right thing" when the process using it forks:	2348	Usage of pthreads in a program changes the semantics of fork
		2349	considerably. Specifically, only async-safe functions can be called after
		2350	fork. Perl doesn't know about this, so in general, you cannot call fork
		2351	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2352	pthreads, so this applies, but many other extensions and (for inexplicable
		2353	reasons) perl itself often is linked against pthreads, so this limitation
		2354	applies to quite a lot of perls.
1746		2355
1747	Before the fork, IO::AIO enters a quiescent state where no requests	2356	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1748	can be added in other threads and no results will be processed. After	2357	only works in the process that loaded it. Forking is fully supported, but
1749	the fork the parent simply leaves the quiescent state and continues	2358	using IO::AIO in the child is not.
1750	request/result processing, while the child frees the request/result queue
1751	(so that the requests started before the fork will only be handled in the
1752	parent). Threads will be started on demand until the limit set in the
1753	parent process has been reached again.
1754		2359
1755	In short: the parent will, after a short pause, continue as if fork had	2360	You might get around by not I<using> IO::AIO before (or after)
1756	not been called, while the child will act as if IO::AIO has not been used	2361	forking. You could also try to call the L<IO::AIO::reinit> function in the
1757	yet.	2362	child:
		2363
		2364	=over 4
		2365
		2366	=item IO::AIO::reinit
		2367
		2368	Abandons all current requests and I/O threads and simply reinitialises all
		2369	data structures. This is not an operation supported by any standards, but
		2370	happens to work on GNU/Linux and some newer BSD systems.
		2371
		2372	The only reasonable use for this function is to call it after forking, if
		2373	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2374	the process will result in undefined behaviour. Calling it at any time
		2375	will also result in any undefined (by POSIX) behaviour.
		2376
		2377	=back
		2378
		2379	=head2 LINUX-SPECIFIC CALLS
		2380
		2381	When a call is documented as "linux-specific" then this means it
		2382	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2383	availability and compatibility of such calls regardless of the platform
		2384	it is compiled on, so platforms such as FreeBSD which often implement
		2385	these calls will work. When in doubt, call them and see if they fail wth
		2386	C<ENOSYS>.
1758		2387
1759	=head2 MEMORY USAGE	2388	=head2 MEMORY USAGE
1760		2389
1761	Per-request usage:	2390	Per-request usage:
1762		2391
…		…
1775	temporary buffers, and each thread requires a stack and other data	2404	temporary buffers, and each thread requires a stack and other data
1776	structures (usually around 16k-128k, depending on the OS).	2405	structures (usually around 16k-128k, depending on the OS).
1777		2406
1778	=head1 KNOWN BUGS	2407	=head1 KNOWN BUGS
1779		2408
1780	Known bugs will be fixed in the next release.	2409	Known bugs will be fixed in the next release :)
		2410
		2411	=head1 KNOWN ISSUES
		2412
		2413	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2414	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2415	non-created hash slots or other scalars I didn't think of. It's best to
		2416	avoid such and either use scalar variables or making sure that the scalar
		2417	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2418
		2419	I am not sure anything can be done about this, so this is considered a
		2420	known issue, rather than a bug.
1781		2421
1782	=head1 SEE ALSO	2422	=head1 SEE ALSO
1783		2423
1784	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2424	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1785	more natural syntax.	2425	more natural syntax.

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