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Revision 1.182 by root, Sun Sep 12 03:36:27 2010 UTC vs.
Revision 1.275 by root, Fri Sep 22 05:20:39 2017 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '3.65';	176	our $VERSION = 4.35;
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_wd);
184		189
185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	190	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	191	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
187	min_parallel max_parallel max_idle	192	min_parallel max_parallel max_idle idle_timeout
188	nreqs nready npending nthreads	193	nreqs nready npending nthreads
189	max_poll_time max_poll_reqs	194	max_poll_time max_poll_reqs
190	sendfile fadvise madvise	195	sendfile fadvise madvise
191	mmap munmap munlock munlockall);	196	mmap munmap munlock munlockall);
192		197
…		…
200		205
201	=head1 FUNCTIONS	206	=head1 FUNCTIONS
202		207
203	=head2 QUICK OVERVIEW	208	=head2 QUICK OVERVIEW
204		209
205	This section simply lists the prototypes of the most important functions	210	This section simply lists the prototypes most of the functions for
206	for quick reference. See the following sections for function-by-function	211	quick reference. See the following sections for function-by-function
207	documentation.	212	documentation.
208		213
		214	aio_wd $pathname, $callback->($wd)
209	aio_open $pathname, $flags, $mode, $callback->($fh)	215	aio_open $pathname, $flags, $mode, $callback->($fh)
210	aio_close $fh, $callback->($status)	216	aio_close $fh, $callback->($status)
		217	aio_seek $fh,$offset,$whence, $callback->($offs)
211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	218	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	220	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214	aio_readahead $fh,$offset,$length, $callback->($retval)	221	aio_readahead $fh,$offset,$length, $callback->($retval)
215	aio_stat $fh_or_path, $callback->($status)	222	aio_stat $fh_or_path, $callback->($status)
216	aio_lstat $fh, $callback->($status)	223	aio_lstat $fh, $callback->($status)
217	aio_statvfs $fh_or_path, $callback->($statvfs)	224	aio_statvfs $fh_or_path, $callback->($statvfs)
218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	225	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	226	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		227	aio_chmod $fh_or_path, $mode, $callback->($status)
220	aio_truncate $fh_or_path, $offset, $callback->($status)	228	aio_truncate $fh_or_path, $offset, $callback->($status)
221	aio_chmod $fh_or_path, $mode, $callback->($status)	229	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		230	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
222	aio_unlink $pathname, $callback->($status)	231	aio_unlink $pathname, $callback->($status)
223	aio_mknod $path, $mode, $dev, $callback->($status)	232	aio_mknod $pathname, $mode, $dev, $callback->($status)
224	aio_link $srcpath, $dstpath, $callback->($status)	233	aio_link $srcpath, $dstpath, $callback->($status)
225	aio_symlink $srcpath, $dstpath, $callback->($status)	234	aio_symlink $srcpath, $dstpath, $callback->($status)
226	aio_readlink $path, $callback->($link)	235	aio_readlink $pathname, $callback->($link)
		236	aio_realpath $pathname, $callback->($path)
227	aio_rename $srcpath, $dstpath, $callback->($status)	237	aio_rename $srcpath, $dstpath, $callback->($status)
		238	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
228	aio_mkdir $pathname, $mode, $callback->($status)	239	aio_mkdir $pathname, $mode, $callback->($status)
229	aio_rmdir $pathname, $callback->($status)	240	aio_rmdir $pathname, $callback->($status)
230	aio_readdir $pathname, $callback->($entries)	241	aio_readdir $pathname, $callback->($entries)
231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	242	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	243	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	244	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		245	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
234	aio_load $path, $data, $callback->($status)	246	aio_load $pathname, $data, $callback->($status)
235	aio_copy $srcpath, $dstpath, $callback->($status)	247	aio_copy $srcpath, $dstpath, $callback->($status)
236	aio_move $srcpath, $dstpath, $callback->($status)	248	aio_move $srcpath, $dstpath, $callback->($status)
237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238	aio_rmtree $path, $callback->($status)	249	aio_rmtree $pathname, $callback->($status)
		250	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		251	aio_ioctl $fh, $request, $buf, $callback->($status)
239	aio_sync $callback->($status)	252	aio_sync $callback->($status)
		253	aio_syncfs $fh, $callback->($status)
240	aio_fsync $fh, $callback->($status)	254	aio_fsync $fh, $callback->($status)
241	aio_fdatasync $fh, $callback->($status)	255	aio_fdatasync $fh, $callback->($status)
242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	256	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243	aio_pathsync $path, $callback->($status)	257	aio_pathsync $pathname, $callback->($status)
244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	258	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	260	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247	aio_mlockall $flags, $callback->($status)	261	aio_mlockall $flags, $callback->($status)
248	aio_group $callback->(...)	262	aio_group $callback->(...)
249	aio_nop $callback->()	263	aio_nop $callback->()
…		…
258	IO::AIO::max_poll_reqs $nreqs	272	IO::AIO::max_poll_reqs $nreqs
259	IO::AIO::max_poll_time $seconds	273	IO::AIO::max_poll_time $seconds
260	IO::AIO::min_parallel $nthreads	274	IO::AIO::min_parallel $nthreads
261	IO::AIO::max_parallel $nthreads	275	IO::AIO::max_parallel $nthreads
262	IO::AIO::max_idle $nthreads	276	IO::AIO::max_idle $nthreads
		277	IO::AIO::idle_timeout $seconds
263	IO::AIO::max_outstanding $maxreqs	278	IO::AIO::max_outstanding $maxreqs
264	IO::AIO::nreqs	279	IO::AIO::nreqs
265	IO::AIO::nready	280	IO::AIO::nready
266	IO::AIO::npending	281	IO::AIO::npending
		282	IO::AIO::min_fdlimit $nfd;
267		283
268	IO::AIO::sendfile $ofh, $ifh, $offset, $count	284	IO::AIO::sendfile $ofh, $ifh, $offset, $count
269	IO::AIO::fadvise $fh, $offset, $len, $advice	285	IO::AIO::fadvise $fh, $offset, $len, $advice
		286	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		287	IO::AIO::munmap $scalar
		288	IO::AIO::madvise $scalar, $offset, $length, $advice
		289	IO::AIO::mprotect $scalar, $offset, $length, $protect
270	IO::AIO::munlock $scalar, $offset = 0, $length = undef	290	IO::AIO::munlock $scalar, $offset = 0, $length = undef
271	IO::AIO::munlockall	291	IO::AIO::munlockall
272		292
273	=head2 AIO REQUEST FUNCTIONS	293	=head2 API NOTES
274		294
275	All the C<aio_*> calls are more or less thin wrappers around the syscall	295	All the C<aio_*> calls are more or less thin wrappers around the syscall
276	with the same name (sans C<aio_>). The arguments are similar or identical,	296	with the same name (sans C<aio_>). The arguments are similar or identical,
277	and they all accept an additional (and optional) C<$callback> argument	297	and they all accept an additional (and optional) C<$callback> argument
278	which must be a code reference. This code reference will get called with	298	which must be a code reference. This code reference will be called after
279	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	299	the syscall has been executed in an asynchronous fashion. The results
280	perl, which usually delivers "false") as its sole argument after the given	300	of the request will be passed as arguments to the callback (and, if an
281	syscall has been executed asynchronously.	301	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		302	most syscalls return C<-1> on error, unlike perl, which usually delivers
		303	"false").
		304
		305	Some requests (such as C<aio_readdir>) pass the actual results and
		306	communicate failures by passing C<undef>.
282		307
283	All functions expecting a filehandle keep a copy of the filehandle	308	All functions expecting a filehandle keep a copy of the filehandle
284	internally until the request has finished.	309	internally until the request has finished.
285		310
286	All functions return request objects of type L<IO::AIO::REQ> that allow	311	All functions return request objects of type L<IO::AIO::REQ> that allow
287	further manipulation of those requests while they are in-flight.	312	further manipulation of those requests while they are in-flight.
288		313
289	The pathnames you pass to these routines I<must> be absolute and	314	The pathnames you pass to these routines I<should> be absolute. The
290	encoded as octets. The reason for the former is that at the time the	315	reason for this is that at the time the request is being executed, the
291	request is being executed, the current working directory could have	316	current working directory could have changed. Alternatively, you can
292	changed. Alternatively, you can make sure that you never change the	317	make sure that you never change the current working directory anywhere
293	current working directory anywhere in the program and then use relative	318	in the program and then use relative paths. You can also take advantage
294	paths.	319	of IO::AIOs working directory abstraction, that lets you specify paths
		320	relative to some previously-opened "working directory object" - see the
		321	description of the C<IO::AIO::WD> class later in this document.
295		322
296	To encode pathnames as octets, either make sure you either: a) always pass	323	To encode pathnames as octets, either make sure you either: a) always pass
297	in filenames you got from outside (command line, readdir etc.) without	324	in filenames you got from outside (command line, readdir etc.) without
298	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	325	tinkering, b) are in your native filesystem encoding, c) use the Encode
299	your pathnames to the locale (or other) encoding in effect in the user	326	module and encode your pathnames to the locale (or other) encoding in
300	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	327	effect in the user environment, d) use Glib::filename_from_unicode on
301	use something else to ensure your scalar has the correct contents.	328	unicode filenames or e) use something else to ensure your scalar has the
		329	correct contents.
302		330
303	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	331	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
304	handles correctly whether it is set or not.	332	handles correctly whether it is set or not.
		333
		334	=head2 AIO REQUEST FUNCTIONS
305		335
306	=over 4	336	=over 4
307		337
308	=item $prev_pri = aioreq_pri [$pri]	338	=item $prev_pri = aioreq_pri [$pri]
309		339
…		…
339		369
340		370
341	=item aio_open $pathname, $flags, $mode, $callback->($fh)	371	=item aio_open $pathname, $flags, $mode, $callback->($fh)
342		372
343	Asynchronously open or create a file and call the callback with a newly	373	Asynchronously open or create a file and call the callback with a newly
344	created filehandle for the file.	374	created filehandle for the file (or C<undef> in case of an error).
345		375
346	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	376	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
347	for an explanation.	377	for an explanation.
348		378
349	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	379	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
365	} else {	395	} else {
366	die "open failed: $!\n";	396	die "open failed: $!\n";
367	}	397	}
368	};	398	};
369		399
		400	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		401	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		402	following POSIX and non-POSIX constants are available (missing ones on
		403	your system are, as usual, C<0>):
		404
		405	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		406	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		407	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		408
370		409
371	=item aio_close $fh, $callback->($status)	410	=item aio_close $fh, $callback->($status)
372		411
373	Asynchronously close a file and call the callback with the result	412	Asynchronously close a file and call the callback with the result
374	code.	413	code.
…		…
383	Or in other words: the file descriptor will be closed, but it will not be	422	Or in other words: the file descriptor will be closed, but it will not be
384	free for reuse until the perl filehandle is closed.	423	free for reuse until the perl filehandle is closed.
385		424
386	=cut	425	=cut
387		426
		427	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		428
		429	Seeks the filehandle to the new C<$offset>, similarly to perl's
		430	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		431	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		432	C<IO::AIO::SEEK_END>).
		433
		434	The resulting absolute offset will be passed to the callback, or C<-1> in
		435	case of an error.
		436
		437	In theory, the C<$whence> constants could be different than the
		438	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		439	so don't panic.
		440
		441	As a GNU/Linux (and maybe Solaris) extension, also the constants
		442	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		443	could be found. No guarantees about suitability for use in C<aio_seek> or
		444	Perl's C<sysseek> can be made though, although I would naively assume they
		445	"just work".
		446
388	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	447	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
389		448
390	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	449	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
391		450
392	Reads or writes C<$length> bytes from or to the specified C<$fh> and	451	Reads or writes C<$length> bytes from or to the specified C<$fh> and
393	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	452	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
394	and calls the callback without the actual number of bytes read (or -1 on	453	calls the callback with the actual number of bytes transferred (or -1 on
395	error, just like the syscall).	454	error, just like the syscall).
396		455
397	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	456	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
398	offset plus the actual number of bytes read.	457	offset plus the actual number of bytes read.
399		458
…		…
424		483
425	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	484	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
426	reading at byte offset C<$in_offset>, and starts writing at the current	485	reading at byte offset C<$in_offset>, and starts writing at the current
427	file offset of C<$out_fh>. Because of that, it is not safe to issue more	486	file offset of C<$out_fh>. Because of that, it is not safe to issue more
428	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	487	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
429	other.	488	other. The same C<$in_fh> works fine though, as this function does not
		489	move or use the file offset of C<$in_fh>.
430		490
		491	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		492	are written, and there is no way to find out how many more bytes have been
		493	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		494	number of bytes written to C<$out_fh>. Only if the result value equals
		495	C<$length> one can assume that C<$length> bytes have been read.
		496
		497	Unlike with other C<aio_> functions, it makes a lot of sense to use
		498	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		499	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		500	the socket I/O will be non-blocking. Note, however, that you can run
		501	into a trap where C<aio_sendfile> reads some data with readahead, then
		502	fails to write all data, and when the socket is ready the next time, the
		503	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		504	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		505	resource usage.
		506
431	This call tries to make use of a native C<sendfile> syscall to provide	507	This call tries to make use of a native C<sendfile>-like syscall to
432	zero-copy operation. For this to work, C<$out_fh> should refer to a	508	provide zero-copy operation. For this to work, C<$out_fh> should refer to
433	socket, and C<$in_fh> should refer to an mmap'able file.	509	a socket, and C<$in_fh> should refer to an mmap'able file.
434		510
435	If a native sendfile cannot be found or it fails with C<ENOSYS>,	511	If a native sendfile cannot be found or it fails with C<ENOSYS>,
436	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	512	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
437	it will be emulated, so you can call C<aio_sendfile> on any type of	513	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
438	filehandle regardless of the limitations of the operating system.	514	type of filehandle regardless of the limitations of the operating system.
439		515
440	Please note, however, that C<aio_sendfile> can read more bytes from	516	As native sendfile syscalls (as practically any non-POSIX interface hacked
441	C<$in_fh> than are written, and there is no way to find out how many	517	together in a hurry to improve benchmark numbers) tend to be rather buggy
442	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	518	on many systems, this implementation tries to work around some known bugs
443	provides the number of bytes written to C<$out_fh>. Only if the result	519	in Linux and FreeBSD kernels (probably others, too), but that might fail,
444	value equals C<$length> one can assume that C<$length> bytes have been	520	so you really really should check the return value of C<aio_sendfile> -
445	read.	521	fewer bytes than expected might have been transferred.
446		522
447		523
448	=item aio_readahead $fh,$offset,$length, $callback->($retval)	524	=item aio_readahead $fh,$offset,$length, $callback->($retval)
449		525
450	C<aio_readahead> populates the page cache with data from a file so that	526	C<aio_readahead> populates the page cache with data from a file so that
…		…
454	whole pages, so that offset is effectively rounded down to a page boundary	530	whole pages, so that offset is effectively rounded down to a page boundary
455	and bytes are read up to the next page boundary greater than or equal to	531	and bytes are read up to the next page boundary greater than or equal to
456	(off-set+length). C<aio_readahead> does not read beyond the end of the	532	(off-set+length). C<aio_readahead> does not read beyond the end of the
457	file. The current file offset of the file is left unchanged.	533	file. The current file offset of the file is left unchanged.
458		534
459	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	535	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
460	emulated by simply reading the data, which would have a similar effect.	536	be emulated by simply reading the data, which would have a similar effect.
461		537
462		538
463	=item aio_stat $fh_or_path, $callback->($status)	539	=item aio_stat $fh_or_path, $callback->($status)
464		540
465	=item aio_lstat $fh, $callback->($status)	541	=item aio_lstat $fh, $callback->($status)
…		…
472	for an explanation.	548	for an explanation.
473		549
474	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	550	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
475	error when stat'ing a large file, the results will be silently truncated	551	error when stat'ing a large file, the results will be silently truncated
476	unless perl itself is compiled with large file support.	552	unless perl itself is compiled with large file support.
		553
		554	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		555	following constants and functions (if not implemented, the constants will
		556	be C<0> and the functions will either C<croak> or fall back on traditional
		557	behaviour).
		558
		559	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		560	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		561	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
477		562
478	Example: Print the length of F</etc/passwd>:	563	Example: Print the length of F</etc/passwd>:
479		564
480	aio_stat "/etc/passwd", sub {	565	aio_stat "/etc/passwd", sub {
481	$_[0] and die "stat failed: $!";	566	$_[0] and die "stat failed: $!";
…		…
525	namemax => 255,	610	namemax => 255,
526	frsize => 1024,	611	frsize => 1024,
527	fsid => 1810	612	fsid => 1810
528	}	613	}
529		614
		615	Here is a (likely partial - send me updates!) list of fsid values used by
		616	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		617
		618	0x0000adf5 adfs
		619	0x0000adff affs
		620	0x5346414f afs
		621	0x09041934 anon-inode filesystem
		622	0x00000187 autofs
		623	0x42465331 befs
		624	0x1badface bfs
		625	0x42494e4d binfmt_misc
		626	0x9123683e btrfs
		627	0x0027e0eb cgroupfs
		628	0xff534d42 cifs
		629	0x73757245 coda
		630	0x012ff7b7 coh
		631	0x28cd3d45 cramfs
		632	0x453dcd28 cramfs-wend (wrong endianness)
		633	0x64626720 debugfs
		634	0x00001373 devfs
		635	0x00001cd1 devpts
		636	0x0000f15f ecryptfs
		637	0x00414a53 efs
		638	0x0000137d ext
		639	0x0000ef53 ext2/ext3/ext4
		640	0x0000ef51 ext2
		641	0xf2f52010 f2fs
		642	0x00004006 fat
		643	0x65735546 fuseblk
		644	0x65735543 fusectl
		645	0x0bad1dea futexfs
		646	0x01161970 gfs2
		647	0x47504653 gpfs
		648	0x00004244 hfs
		649	0xf995e849 hpfs
		650	0x00c0ffee hostfs
		651	0x958458f6 hugetlbfs
		652	0x2bad1dea inotifyfs
		653	0x00009660 isofs
		654	0x000072b6 jffs2
		655	0x3153464a jfs
		656	0x6b414653 k-afs
		657	0x0bd00bd0 lustre
		658	0x0000137f minix
		659	0x0000138f minix 30 char names
		660	0x00002468 minix v2
		661	0x00002478 minix v2 30 char names
		662	0x00004d5a minix v3
		663	0x19800202 mqueue
		664	0x00004d44 msdos
		665	0x0000564c novell
		666	0x00006969 nfs
		667	0x6e667364 nfsd
		668	0x00003434 nilfs
		669	0x5346544e ntfs
		670	0x00009fa1 openprom
		671	0x7461636F ocfs2
		672	0x00009fa0 proc
		673	0x6165676c pstorefs
		674	0x0000002f qnx4
		675	0x68191122 qnx6
		676	0x858458f6 ramfs
		677	0x52654973 reiserfs
		678	0x00007275 romfs
		679	0x67596969 rpc_pipefs
		680	0x73636673 securityfs
		681	0xf97cff8c selinux
		682	0x0000517b smb
		683	0x534f434b sockfs
		684	0x73717368 squashfs
		685	0x62656572 sysfs
		686	0x012ff7b6 sysv2
		687	0x012ff7b5 sysv4
		688	0x01021994 tmpfs
		689	0x15013346 udf
		690	0x00011954 ufs
		691	0x54190100 ufs byteswapped
		692	0x00009fa2 usbdevfs
		693	0x01021997 v9fs
		694	0xa501fcf5 vxfs
		695	0xabba1974 xenfs
		696	0x012ff7b4 xenix
		697	0x58465342 xfs
		698	0x012fd16d xia
530		699
531	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	700	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
532		701
533	Works like perl's C<utime> function (including the special case of $atime	702	Works like perl's C<utime> function (including the special case of $atime
534	and $mtime being undef). Fractional times are supported if the underlying	703	and $mtime being undef). Fractional times are supported if the underlying
…		…
562	=item aio_truncate $fh_or_path, $offset, $callback->($status)	731	=item aio_truncate $fh_or_path, $offset, $callback->($status)
563		732
564	Works like truncate(2) or ftruncate(2).	733	Works like truncate(2) or ftruncate(2).
565		734
566		735
		736	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		737
		738	Allocates or frees disk space according to the C<$mode> argument. See the
		739	linux C<fallocate> documentation for details.
		740
		741	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		742	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		743	to deallocate a file range.
		744
		745	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		746	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		747	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		748	to unshare shared blocks (see your L<fallocate(2)> manpage).
		749
		750	The file system block size used by C<fallocate> is presumably the
		751	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		752	can dictate other limitations.
		753
		754	If C<fallocate> isn't available or cannot be emulated (currently no
		755	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		756
		757
567	=item aio_chmod $fh_or_path, $mode, $callback->($status)	758	=item aio_chmod $fh_or_path, $mode, $callback->($status)
568		759
569	Works like perl's C<chmod> function.	760	Works like perl's C<chmod> function.
570		761
571		762
…		…
573		764
574	Asynchronously unlink (delete) a file and call the callback with the	765	Asynchronously unlink (delete) a file and call the callback with the
575	result code.	766	result code.
576		767
577		768
578	=item aio_mknod $path, $mode, $dev, $callback->($status)	769	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
579		770
580	[EXPERIMENTAL]	771	[EXPERIMENTAL]
581		772
582	Asynchronously create a device node (or fifo). See mknod(2).	773	Asynchronously create a device node (or fifo). See mknod(2).
583		774
584	The only (POSIX-) portable way of calling this function is:	775	The only (POSIX-) portable way of calling this function is:
585		776
586	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	777	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
587		778
		779	See C<aio_stat> for info about some potentially helpful extra constants
		780	and functions.
588		781
589	=item aio_link $srcpath, $dstpath, $callback->($status)	782	=item aio_link $srcpath, $dstpath, $callback->($status)
590		783
591	Asynchronously create a new link to the existing object at C<$srcpath> at	784	Asynchronously create a new link to the existing object at C<$srcpath> at
592	the path C<$dstpath> and call the callback with the result code.	785	the path C<$dstpath> and call the callback with the result code.
…		…
596		789
597	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	790	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
598	the path C<$dstpath> and call the callback with the result code.	791	the path C<$dstpath> and call the callback with the result code.
599		792
600		793
601	=item aio_readlink $path, $callback->($link)	794	=item aio_readlink $pathname, $callback->($link)
602		795
603	Asynchronously read the symlink specified by C<$path> and pass it to	796	Asynchronously read the symlink specified by C<$path> and pass it to
604	the callback. If an error occurs, nothing or undef gets passed to the	797	the callback. If an error occurs, nothing or undef gets passed to the
605	callback.	798	callback.
606		799
607		800
		801	=item aio_realpath $pathname, $callback->($path)
		802
		803	Asynchronously make the path absolute and resolve any symlinks in
		804	C<$path>. The resulting path only consists of directories (same as
		805	L<Cwd::realpath>).
		806
		807	This request can be used to get the absolute path of the current working
		808	directory by passing it a path of F<.> (a single dot).
		809
		810
608	=item aio_rename $srcpath, $dstpath, $callback->($status)	811	=item aio_rename $srcpath, $dstpath, $callback->($status)
609		812
610	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	813	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
611	rename(2) and call the callback with the result code.	814	rename(2) and call the callback with the result code.
		815
		816	On systems that support the AIO::WD working directory abstraction
		817	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		818	of failing, C<rename> is called on the absolute path of C<$wd>.
		819
		820
		821	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		822
		823	Basically a version of C<aio_rename> with an additional C<$flags>
		824	argument. Calling this with C<$flags=0> is the same as calling
		825	C<aio_rename>.
		826
		827	Non-zero flags are currently only supported on GNU/Linux systems that
		828	support renameat2. Other systems fail with C<ENOSYS> in this case.
		829
		830	The following constants are available (missing ones are, as usual C<0>),
		831	see renameat2(2) for details:
		832
		833	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		834	and C<IO::AIO::RENAME_WHITEOUT>.
612		835
613		836
614	=item aio_mkdir $pathname, $mode, $callback->($status)	837	=item aio_mkdir $pathname, $mode, $callback->($status)
615		838
616	Asynchronously mkdir (create) a directory and call the callback with	839	Asynchronously mkdir (create) a directory and call the callback with
…		…
621	=item aio_rmdir $pathname, $callback->($status)	844	=item aio_rmdir $pathname, $callback->($status)
622		845
623	Asynchronously rmdir (delete) a directory and call the callback with the	846	Asynchronously rmdir (delete) a directory and call the callback with the
624	result code.	847	result code.
625		848
		849	On systems that support the AIO::WD working directory abstraction
		850	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		851	C<rmdir> is called on the absolute path of C<$wd>.
		852
626		853
627	=item aio_readdir $pathname, $callback->($entries)	854	=item aio_readdir $pathname, $callback->($entries)
628		855
629	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	856	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
630	directory (i.e. opendir + readdir + closedir). The entries will not be	857	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
634	array-ref with the filenames.	861	array-ref with the filenames.
635		862
636		863
637	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	864	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
638		865
639	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	866	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
640	behaviour and output format. In case of an error, C<$entries> will be	867	tune behaviour and output format. In case of an error, C<$entries> will be
641	C<undef>.	868	C<undef>.
642		869
643	The flags are a combination of the following constants, ORed together (the	870	The flags are a combination of the following constants, ORed together (the
644	flags will also be passed to the callback, possibly modified):	871	flags will also be passed to the callback, possibly modified):
645		872
646	=over 4	873	=over 4
647		874
648	=item IO::AIO::READDIR_DENTS	875	=item IO::AIO::READDIR_DENTS
649		876
650	When this flag is off, then the callback gets an arrayref with of names	877	When this flag is off, then the callback gets an arrayref consisting of
651	only (as with C<aio_readdir>), otherwise it gets an arrayref with	878	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
652	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	879	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
653	entry in more detail.	880	entry in more detail.
654		881
655	C<$name> is the name of the entry.	882	C<$name> is the name of the entry.
656		883
…		…
669	systems that do not deliver the inode information.	896	systems that do not deliver the inode information.
670		897
671	=item IO::AIO::READDIR_DIRS_FIRST	898	=item IO::AIO::READDIR_DIRS_FIRST
672		899
673	When this flag is set, then the names will be returned in an order where	900	When this flag is set, then the names will be returned in an order where
674	likely directories come first. This is useful when you need to quickly	901	likely directories come first, in optimal stat order. This is useful when
675	find directories, or you want to find all directories while avoiding to	902	you need to quickly find directories, or you want to find all directories
676	stat() each entry.	903	while avoiding to stat() each entry.
677		904
678	If the system returns type information in readdir, then this is used	905	If the system returns type information in readdir, then this is used
679	to find directories directly. Otherwise, likely directories are files	906	to find directories directly. Otherwise, likely directories are names
680	beginning with ".", or otherwise files with no dots, of which files with	907	beginning with ".", or otherwise names with no dots, of which names with
681	short names are tried first.	908	short names are tried first.
682		909
683	=item IO::AIO::READDIR_STAT_ORDER	910	=item IO::AIO::READDIR_STAT_ORDER
684		911
685	When this flag is set, then the names will be returned in an order	912	When this flag is set, then the names will be returned in an order
…		…
692		919
693	=item IO::AIO::READDIR_FOUND_UNKNOWN	920	=item IO::AIO::READDIR_FOUND_UNKNOWN
694		921
695	This flag should not be set when calling C<aio_readdirx>. Instead, it	922	This flag should not be set when calling C<aio_readdirx>. Instead, it
696	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	923	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
697	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	924	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
698	C<$type>'s are known, which can be used to speed up some algorithms.	925	C<$type>'s are known, which can be used to speed up some algorithms.
699		926
700	=back	927	=back
701		928
702		929
703	=item aio_load $path, $data, $callback->($status)	930	=item aio_load $pathname, $data, $callback->($status)
704		931
705	This is a composite request that tries to fully load the given file into	932	This is a composite request that tries to fully load the given file into
706	memory. Status is the same as with aio_read.	933	memory. Status is the same as with aio_read.
707		934
708	=cut	935	=cut
…		…
731	=item aio_copy $srcpath, $dstpath, $callback->($status)	958	=item aio_copy $srcpath, $dstpath, $callback->($status)
732		959
733	Try to copy the I<file> (directories not supported as either source or	960	Try to copy the I<file> (directories not supported as either source or
734	destination) from C<$srcpath> to C<$dstpath> and call the callback with	961	destination) from C<$srcpath> to C<$dstpath> and call the callback with
735	a status of C<0> (ok) or C<-1> (error, see C<$!>).	962	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		963
		964	Existing destination files will be truncated.
736		965
737	This is a composite request that creates the destination file with	966	This is a composite request that creates the destination file with
738	mode 0200 and copies the contents of the source file into it using	967	mode 0200 and copies the contents of the source file into it using
739	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	968	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
740	uid/gid, in that order.	969	uid/gid, in that order.
…		…
830	if ($_[0] && $! == EXDEV) {	1059	if ($_[0] && $! == EXDEV) {
831	aioreq_pri $pri;	1060	aioreq_pri $pri;
832	add $grp aio_copy $src, $dst, sub {	1061	add $grp aio_copy $src, $dst, sub {
833	$grp->result ($_[0]);	1062	$grp->result ($_[0]);
834		1063
835	if (!$_[0]) {	1064	unless ($_[0]) {
836	aioreq_pri $pri;	1065	aioreq_pri $pri;
837	add $grp aio_unlink $src;	1066	add $grp aio_unlink $src;
838	}	1067	}
839	};	1068	};
840	} else {	1069	} else {
…		…
843	};	1072	};
844		1073
845	$grp	1074	$grp
846	}	1075	}
847		1076
848	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1077	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
849		1078
850	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1079	Scans a directory (similar to C<aio_readdir>) but additionally tries to
851	efficiently separate the entries of directory C<$path> into two sets of	1080	efficiently separate the entries of directory C<$path> into two sets of
852	names, directories you can recurse into (directories), and ones you cannot	1081	names, directories you can recurse into (directories), and ones you cannot
853	recurse into (everything else, including symlinks to directories).	1082	recurse into (everything else, including symlinks to directories).
…		…
884	Then entries will be sorted into likely directories a non-initial dot	1113	Then entries will be sorted into likely directories a non-initial dot
885	currently) and likely non-directories (see C<aio_readdirx>). Then every	1114	currently) and likely non-directories (see C<aio_readdirx>). Then every
886	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1115	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
887	in order of their inode numbers. If that succeeds, it assumes that the	1116	in order of their inode numbers. If that succeeds, it assumes that the
888	entry is a directory or a symlink to directory (which will be checked	1117	entry is a directory or a symlink to directory (which will be checked
889	seperately). This is often faster than stat'ing the entry itself because	1118	separately). This is often faster than stat'ing the entry itself because
890	filesystems might detect the type of the entry without reading the inode	1119	filesystems might detect the type of the entry without reading the inode
891	data (e.g. ext2fs filetype feature), even on systems that cannot return	1120	data (e.g. ext2fs filetype feature), even on systems that cannot return
892	the filetype information on readdir.	1121	the filetype information on readdir.
893		1122
894	If the known number of directories (link count - 2) has been reached, the	1123	If the known number of directories (link count - 2) has been reached, the
…		…
910		1139
911	my $grp = aio_group $cb;	1140	my $grp = aio_group $cb;
912		1141
913	$maxreq = 4 if $maxreq <= 0;	1142	$maxreq = 4 if $maxreq <= 0;
914		1143
915	# stat once	1144	# get a wd object
916	aioreq_pri $pri;	1145	aioreq_pri $pri;
917	add $grp aio_stat $path, sub {	1146	add $grp aio_wd $path, sub {
		1147	$_[0]
918	return $grp->result () if $_[0];	1148	or return $grp->result ();
919	my $now = time;
920	my $hash1 = join ":", (stat _)[0,1,3,7,9];
921		1149
922	# read the directory entries	1150	my $wd = [shift, "."];
		1151
		1152	# stat once
923	aioreq_pri $pri;	1153	aioreq_pri $pri;
924	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1154	add $grp aio_stat $wd, sub {
925	my $entries = shift
926	or return $grp->result ();	1155	return $grp->result () if $_[0];
		1156	my $now = time;
		1157	my $hash1 = join ":", (stat _)[0,1,3,7,9];
927		1158
928	# stat the dir another time	1159	# read the directory entries
929	aioreq_pri $pri;	1160	aioreq_pri $pri;
		1161	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1162	my $entries = shift
		1163	or return $grp->result ();
		1164
		1165	# stat the dir another time
		1166	aioreq_pri $pri;
930	add $grp aio_stat $path, sub {	1167	add $grp aio_stat $wd, sub {
931	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1168	my $hash2 = join ":", (stat _)[0,1,3,7,9];
932		1169
933	my $ndirs;	1170	my $ndirs;
934		1171
935	# take the slow route if anything looks fishy	1172	# take the slow route if anything looks fishy
936	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1173	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
937	$ndirs = -1;	1174	$ndirs = -1;
938	} else {	1175	} else {
939	# if nlink == 2, we are finished	1176	# if nlink == 2, we are finished
940	# for non-posix-fs's, we rely on nlink < 2	1177	# for non-posix-fs's, we rely on nlink < 2
941	$ndirs = (stat _)[3] - 2	1178	$ndirs = (stat _)[3] - 2
942	or return $grp->result ([], $entries);	1179	or return $grp->result ([], $entries);
943	}	1180	}
944		1181
945	my (@dirs, @nondirs);	1182	my (@dirs, @nondirs);
946		1183
947	my $statgrp = add $grp aio_group sub {	1184	my $statgrp = add $grp aio_group sub {
948	$grp->result (\@dirs, \@nondirs);	1185	$grp->result (\@dirs, \@nondirs);
949	};	1186	};
950		1187
951	limit $statgrp $maxreq;	1188	limit $statgrp $maxreq;
952	feed $statgrp sub {	1189	feed $statgrp sub {
953	return unless @$entries;	1190	return unless @$entries;
954	my $entry = shift @$entries;	1191	my $entry = shift @$entries;
955		1192
956	aioreq_pri $pri;	1193	aioreq_pri $pri;
		1194	$wd->[1] = "$entry/.";
957	add $statgrp aio_stat "$path/$entry/.", sub {	1195	add $statgrp aio_stat $wd, sub {
958	if ($_[0] < 0) {	1196	if ($_[0] < 0) {
959	push @nondirs, $entry;	1197	push @nondirs, $entry;
960	} else {	1198	} else {
961	# need to check for real directory	1199	# need to check for real directory
962	aioreq_pri $pri;	1200	aioreq_pri $pri;
		1201	$wd->[1] = $entry;
963	add $statgrp aio_lstat "$path/$entry", sub {	1202	add $statgrp aio_lstat $wd, sub {
964	if (-d _) {	1203	if (-d _) {
965	push @dirs, $entry;	1204	push @dirs, $entry;
966		1205
967	unless (--$ndirs) {	1206	unless (--$ndirs) {
968	push @nondirs, @$entries;	1207	push @nondirs, @$entries;
969	feed $statgrp;	1208	feed $statgrp;
		1209	}
		1210	} else {
		1211	push @nondirs, $entry;
970	}	1212	}
971	} else {
972	push @nondirs, $entry;
973	}	1213	}
974	}	1214	}
975	}	1215	};
976	};	1216	};
977	};	1217	};
978	};	1218	};
979	};	1219	};
980	};	1220	};
981		1221
982	$grp	1222	$grp
983	}	1223	}
984		1224
985	=item aio_rmtree $path, $callback->($status)	1225	=item aio_rmtree $pathname, $callback->($status)
986		1226
987	Delete a directory tree starting (and including) C<$path>, return the	1227	Delete a directory tree starting (and including) C<$path>, return the
988	status of the final C<rmdir> only. This is a composite request that	1228	status of the final C<rmdir> only. This is a composite request that
989	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1229	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
990	everything else.	1230	everything else.
991		1231
992	=cut	1232	=cut
993		1233
…		…
1015	};	1255	};
1016		1256
1017	$grp	1257	$grp
1018	}	1258	}
1019		1259
		1260	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1261
		1262	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1263
		1264	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1265	they execute asynchronously and pass the return value to the callback.
		1266
		1267	Both calls can be used for a lot of things, some of which make more sense
		1268	to run asynchronously in their own thread, while some others make less
		1269	sense. For example, calls that block waiting for external events, such
		1270	as locking, will also lock down an I/O thread while it is waiting, which
		1271	can deadlock the whole I/O system. At the same time, there might be no
		1272	alternative to using a thread to wait.
		1273
		1274	So in general, you should only use these calls for things that do
		1275	(filesystem) I/O, not for things that wait for other events (network,
		1276	other processes), although if you are careful and know what you are doing,
		1277	you still can.
		1278
		1279	The following constants are available (missing ones are, as usual C<0>):
		1280
		1281	C<F_DUPFD_CLOEXEC>,
		1282
		1283	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1284
		1285	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1286
		1287	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1288	C<FS_IOC_FIEMAP>.
		1289
		1290	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1291	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1292
		1293	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1294	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1295	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1296	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1297	C<FS_FL_USER_MODIFIABLE>.
		1298
		1299	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1300	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1301	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1302	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1303
1020	=item aio_sync $callback->($status)	1304	=item aio_sync $callback->($status)
1021		1305
1022	Asynchronously call sync and call the callback when finished.	1306	Asynchronously call sync and call the callback when finished.
1023		1307
1024	=item aio_fsync $fh, $callback->($status)	1308	=item aio_fsync $fh, $callback->($status)
…		…
1031	Asynchronously call fdatasync on the given filehandle and call the	1315	Asynchronously call fdatasync on the given filehandle and call the
1032	callback with the fdatasync result code.	1316	callback with the fdatasync result code.
1033		1317
1034	If this call isn't available because your OS lacks it or it couldn't be	1318	If this call isn't available because your OS lacks it or it couldn't be
1035	detected, it will be emulated by calling C<fsync> instead.	1319	detected, it will be emulated by calling C<fsync> instead.
		1320
		1321	=item aio_syncfs $fh, $callback->($status)
		1322
		1323	Asynchronously call the syncfs syscall to sync the filesystem associated
		1324	to the given filehandle and call the callback with the syncfs result
		1325	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1326	errno to C<ENOSYS> nevertheless.
1036		1327
1037	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1328	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1038		1329
1039	Sync the data portion of the file specified by C<$offset> and C<$length>	1330	Sync the data portion of the file specified by C<$offset> and C<$length>
1040	to disk (but NOT the metadata), by calling the Linux-specific	1331	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1044	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1335	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1045	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1336	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1046	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1337	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1047	manpage for details.	1338	manpage for details.
1048		1339
1049	=item aio_pathsync $path, $callback->($status)	1340	=item aio_pathsync $pathname, $callback->($status)
1050		1341
1051	This request tries to open, fsync and close the given path. This is a	1342	This request tries to open, fsync and close the given path. This is a
1052	composite request intended to sync directories after directory operations	1343	composite request intended to sync directories after directory operations
1053	(E.g. rename). This might not work on all operating systems or have any	1344	(E.g. rename). This might not work on all operating systems or have any
1054	specific effect, but usually it makes sure that directory changes get	1345	specific effect, but usually it makes sure that directory changes get
…		…
1085	};	1376	};
1086		1377
1087	$grp	1378	$grp
1088	}	1379	}
1089		1380
1090	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1381	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1091		1382
1092	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1383	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1093	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1384	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1094	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1385	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1095	scalar must only be modified in-place while an aio operation is pending on	1386	scalar must only be modified in-place while an aio operation is pending on
…		…
1097		1388
1098	It calls the C<msync> function of your OS, if available, with the memory	1389	It calls the C<msync> function of your OS, if available, with the memory
1099	area starting at C<$offset> in the string and ending C<$length> bytes	1390	area starting at C<$offset> in the string and ending C<$length> bytes
1100	later. If C<$length> is negative, counts from the end, and if C<$length>	1391	later. If C<$length> is negative, counts from the end, and if C<$length>
1101	is C<undef>, then it goes till the end of the string. The flags can be	1392	is C<undef>, then it goes till the end of the string. The flags can be
1102	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1393	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1103	C<IO::AIO::MS_SYNC>.	1394	C<IO::AIO::MS_INVALIDATE>.
1104		1395
1105	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1396	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1106		1397
1107	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1398	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1108	scalars.	1399	scalars.
1109		1400
1110	It touches (reads or writes) all memory pages in the specified	1401	It touches (reads or writes) all memory pages in the specified
1111	range inside the scalar. All caveats and parameters are the same	1402	range inside the scalar. All caveats and parameters are the same
1112	as for C<aio_msync>, above, except for flags, which must be either	1403	as for C<aio_msync>, above, except for flags, which must be either
1113	C<0> (which reads all pages and ensures they are instantiated) or	1404	C<0> (which reads all pages and ensures they are instantiated) or
1114	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1405	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1115	writing an octet from it, which dirties the page).	1406	writing an octet from it, which dirties the page).
1116		1407
1117	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1408	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1118		1409
1119	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1410	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1128	and sets errno to C<ENOSYS>.	1419	and sets errno to C<ENOSYS>.
1129		1420
1130	Note that the corresponding C<munlock> is synchronous and is	1421	Note that the corresponding C<munlock> is synchronous and is
1131	documented under L<MISCELLANEOUS FUNCTIONS>.	1422	documented under L<MISCELLANEOUS FUNCTIONS>.
1132		1423
		1424	Example: open a file, mmap and mlock it - both will be undone when
		1425	C<$data> gets destroyed.
		1426
		1427	open my $fh, "<", $path or die "$path: $!";
		1428	my $data;
		1429	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1430	aio_mlock $data; # mlock in background
		1431
1133	=item aio_mlockall $flags, $callback->($status)	1432	=item aio_mlockall $flags, $callback->($status)
1134		1433
1135	Calls the C<mlockall> function with the given C<$flags> (a combination of	1434	Calls the C<mlockall> function with the given C<$flags> (a combination of
1136	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1435	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1137		1436
1138	On systems that do not implement C<mlockall>, this function returns C<-1>	1437	On systems that do not implement C<mlockall>, this function returns C<-1>
1139	and sets errno to C<ENOSYS>.	1438	and sets errno to C<ENOSYS>.
1140		1439
1141	Note that the corresponding C<munlockall> is synchronous and is	1440	Note that the corresponding C<munlockall> is synchronous and is
1142	documented under L<MISCELLANEOUS FUNCTIONS>.	1441	documented under L<MISCELLANEOUS FUNCTIONS>.
		1442
		1443	Example: asynchronously lock all current and future pages into memory.
		1444
		1445	aio_mlockall IO::AIO::MCL_FUTURE;
		1446
		1447	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1448
		1449	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1450	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1451	the ioctl is not available on your OS, then this request will fail with
		1452	C<ENOSYS>.
		1453
		1454	C<$start> is the starting offset to query extents for, C<$length> is the
		1455	size of the range to query - if it is C<undef>, then the whole file will
		1456	be queried.
		1457
		1458	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1459	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1460	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1461	the data portion.
		1462
		1463	C<$count> is the maximum number of extent records to return. If it is
		1464	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1465	case, if it is C<0>, then the callback receives the number of extents
		1466	instead of the extents themselves (which is unreliable, see below).
		1467
		1468	If an error occurs, the callback receives no arguments. The special
		1469	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1470
		1471	Otherwise, the callback receives an array reference with extent
		1472	structures. Each extent structure is an array reference itself, with the
		1473	following members:
		1474
		1475	[$logical, $physical, $length, $flags]
		1476
		1477	Flags is any combination of the following flag values (typically either C<0>
		1478	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1479
		1480	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1481	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1482	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1483	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1484	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1485	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1486
		1487	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1488	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1489	it to return all extents of a range for files with large number of
		1490	extents. The code works around all these issues if C<$count> is undef.
1143		1491
1144	=item aio_group $callback->(...)	1492	=item aio_group $callback->(...)
1145		1493
1146	This is a very special aio request: Instead of doing something, it is a	1494	This is a very special aio request: Instead of doing something, it is a
1147	container for other aio requests, which is useful if you want to bundle	1495	container for other aio requests, which is useful if you want to bundle
…		…
1184	like sleep and file handle readable/writable, the overhead this creates is	1532	like sleep and file handle readable/writable, the overhead this creates is
1185	immense (it blocks a thread for a long time) so do not use this function	1533	immense (it blocks a thread for a long time) so do not use this function
1186	except to put your application under artificial I/O pressure.	1534	except to put your application under artificial I/O pressure.
1187		1535
1188	=back	1536	=back
		1537
		1538
		1539	=head2 IO::AIO::WD - multiple working directories
		1540
		1541	Your process only has one current working directory, which is used by all
		1542	threads. This makes it hard to use relative paths (some other component
		1543	could call C<chdir> at any time, and it is hard to control when the path
		1544	will be used by IO::AIO).
		1545
		1546	One solution for this is to always use absolute paths. This usually works,
		1547	but can be quite slow (the kernel has to walk the whole path on every
		1548	access), and can also be a hassle to implement.
		1549
		1550	Newer POSIX systems have a number of functions (openat, fdopendir,
		1551	futimensat and so on) that make it possible to specify working directories
		1552	per operation.
		1553
		1554	For portability, and because the clowns who "designed", or shall I write,
		1555	perpetrated this new interface were obviously half-drunk, this abstraction
		1556	cannot be perfect, though.
		1557
		1558	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1559	object. This object stores the canonicalised, absolute version of the
		1560	path, and on systems that allow it, also a directory file descriptor.
		1561
		1562	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1563	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1564	object and a pathname instead (or the IO::AIO::WD object alone, which
		1565	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1566	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1567	to that IO::AIO::WD object.
		1568
		1569	For example, to get a wd object for F</etc> and then stat F<passwd>
		1570	inside, you would write:
		1571
		1572	aio_wd "/etc", sub {
		1573	my $etcdir = shift;
		1574
		1575	# although $etcdir can be undef on error, there is generally no reason
		1576	# to check for errors here, as aio_stat will fail with ENOENT
		1577	# when $etcdir is undef.
		1578
		1579	aio_stat [$etcdir, "passwd"], sub {
		1580	# yay
		1581	};
		1582	};
		1583
		1584	The fact that C<aio_wd> is a request and not a normal function shows that
		1585	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1586	which is why it is done asynchronously.
		1587
		1588	To stat the directory obtained with C<aio_wd> above, one could write
		1589	either of the following three request calls:
		1590
		1591	aio_lstat "/etc" , sub { ... # pathname as normal string
		1592	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1593	aio_lstat $wd , sub { ... # shorthand for the previous
		1594
		1595	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1596	object and the pathname string, so you could write the following without
		1597	causing any issues due to C<$path> getting reused:
		1598
		1599	my $path = [$wd, undef];
		1600
		1601	for my $name (qw(abc def ghi)) {
		1602	$path->[1] = $name;
		1603	aio_stat $path, sub {
		1604	# ...
		1605	};
		1606	}
		1607
		1608	There are some caveats: when directories get renamed (or deleted), the
		1609	pathname string doesn't change, so will point to the new directory (or
		1610	nowhere at all), while the directory fd, if available on the system,
		1611	will still point to the original directory. Most functions accepting a
		1612	pathname will use the directory fd on newer systems, and the string on
		1613	older systems. Some functions (such as realpath) will always rely on the
		1614	string form of the pathname.
		1615
		1616	So this functionality is mainly useful to get some protection against
		1617	C<chdir>, to easily get an absolute path out of a relative path for future
		1618	reference, and to speed up doing many operations in the same directory
		1619	(e.g. when stat'ing all files in a directory).
		1620
		1621	The following functions implement this working directory abstraction:
		1622
		1623	=over 4
		1624
		1625	=item aio_wd $pathname, $callback->($wd)
		1626
		1627	Asynchonously canonicalise the given pathname and convert it to an
		1628	IO::AIO::WD object representing it. If possible and supported on the
		1629	system, also open a directory fd to speed up pathname resolution relative
		1630	to this working directory.
		1631
		1632	If something goes wrong, then C<undef> is passwd to the callback instead
		1633	of a working directory object and C<$!> is set appropriately. Since
		1634	passing C<undef> as working directory component of a pathname fails the
		1635	request with C<ENOENT>, there is often no need for error checking in the
		1636	C<aio_wd> callback, as future requests using the value will fail in the
		1637	expected way.
		1638
		1639	=item IO::AIO::CWD
		1640
		1641	This is a compiletime constant (object) that represents the process
		1642	current working directory.
		1643
		1644	Specifying this object as working directory object for a pathname is as if
		1645	the pathname would be specified directly, without a directory object. For
		1646	example, these calls are functionally identical:
		1647
		1648	aio_stat "somefile", sub { ... };
		1649	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1650
		1651	=back
		1652
		1653	To recover the path associated with an IO::AIO::WD object, you can use
		1654	C<aio_realpath>:
		1655
		1656	aio_realpath $wd, sub {
		1657	warn "path is $_[0]\n";
		1658	};
		1659
		1660	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1661	sometimes, fall back to using an absolue path.
1189		1662
1190	=head2 IO::AIO::REQ CLASS	1663	=head2 IO::AIO::REQ CLASS
1191		1664
1192	All non-aggregate C<aio_*> functions return an object of this class when	1665	All non-aggregate C<aio_*> functions return an object of this class when
1193	called in non-void context.	1666	called in non-void context.
…		…
1311		1784
1312	Sets a feeder/generator on this group: every group can have an attached	1785	Sets a feeder/generator on this group: every group can have an attached
1313	generator that generates requests if idle. The idea behind this is that,	1786	generator that generates requests if idle. The idea behind this is that,
1314	although you could just queue as many requests as you want in a group,	1787	although you could just queue as many requests as you want in a group,
1315	this might starve other requests for a potentially long time. For example,	1788	this might starve other requests for a potentially long time. For example,
1316	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1789	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1317	delaying any later requests for a long time.	1790	requests, delaying any later requests for a long time.
1318		1791
1319	To avoid this, and allow incremental generation of requests, you can	1792	To avoid this, and allow incremental generation of requests, you can
1320	instead a group and set a feeder on it that generates those requests. The	1793	instead a group and set a feeder on it that generates those requests. The
1321	feed callback will be called whenever there are few enough (see C<limit>,	1794	feed callback will be called whenever there are few enough (see C<limit>,
1322	below) requests active in the group itself and is expected to queue more	1795	below) requests active in the group itself and is expected to queue more
…		…
1371		1844
1372	See C<poll_cb> for an example.	1845	See C<poll_cb> for an example.
1373		1846
1374	=item IO::AIO::poll_cb	1847	=item IO::AIO::poll_cb
1375		1848
1376	Process some outstanding events on the result pipe. You have to call this	1849	Process some requests that have reached the result phase (i.e. they have
1377	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1850	been executed but the results are not yet reported). You have to call
1378	returned earlier for whatever reason. Returns immediately when no events	1851	this "regularly" to finish outstanding requests.
1379	are outstanding. The amount of events processed depends on the settings of
1380	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1381		1852
		1853	Returns C<0> if all events could be processed (or there were no
		1854	events to process), or C<-1> if it returned earlier for whatever
		1855	reason. Returns immediately when no events are outstanding. The amount
		1856	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1857	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1858
1382	If not all requests were processed for whatever reason, the filehandle	1859	If not all requests were processed for whatever reason, the poll file
1383	will still be ready when C<poll_cb> returns, so normally you don't have to	1860	descriptor will still be ready when C<poll_cb> returns, so normally you
1384	do anything special to have it called later.	1861	don't have to do anything special to have it called later.
		1862
		1863	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1864	ready, it can be beneficial to call this function from loops which submit
		1865	a lot of requests, to make sure the results get processed when they become
		1866	available and not just when the loop is finished and the event loop takes
		1867	over again. This function returns very fast when there are no outstanding
		1868	requests.
1385		1869
1386	Example: Install an Event watcher that automatically calls	1870	Example: Install an Event watcher that automatically calls
1387	IO::AIO::poll_cb with high priority (more examples can be found in the	1871	IO::AIO::poll_cb with high priority (more examples can be found in the
1388	SYNOPSIS section, at the top of this document):	1872	SYNOPSIS section, at the top of this document):
1389		1873
…		…
1391	poll => 'r', async => 1,	1875	poll => 'r', async => 1,
1392	cb => \&IO::AIO::poll_cb);	1876	cb => \&IO::AIO::poll_cb);
1393		1877
1394	=item IO::AIO::poll_wait	1878	=item IO::AIO::poll_wait
1395		1879
1396	If there are any outstanding requests and none of them in the result	1880	Wait until either at least one request is in the result phase or no
1397	phase, wait till the result filehandle becomes ready for reading (simply	1881	requests are outstanding anymore.
1398	does a C<select> on the filehandle. This is useful if you want to	1882
1399	synchronously wait for some requests to finish).	1883	This is useful if you want to synchronously wait for some requests to
		1884	become ready, without actually handling them.
1400		1885
1401	See C<nreqs> for an example.	1886	See C<nreqs> for an example.
1402		1887
1403	=item IO::AIO::poll	1888	=item IO::AIO::poll
1404		1889
…		…
1491		1976
1492	Under normal circumstances you don't need to call this function.	1977	Under normal circumstances you don't need to call this function.
1493		1978
1494	=item IO::AIO::max_idle $nthreads	1979	=item IO::AIO::max_idle $nthreads
1495		1980
1496	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1981	Limit the number of threads (default: 4) that are allowed to idle
1497	threads that did not get a request to process within 10 seconds). That	1982	(i.e., threads that did not get a request to process within the idle
1498	means if a thread becomes idle while C<$nthreads> other threads are also	1983	timeout (default: 10 seconds). That means if a thread becomes idle while
1499	idle, it will free its resources and exit.	1984	C<$nthreads> other threads are also idle, it will free its resources and
		1985	exit.
1500		1986
1501	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1987	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1502	to allow for extremely high load situations, but want to free resources	1988	to allow for extremely high load situations, but want to free resources
1503	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1989	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1504		1990
1505	The default is probably ok in most situations, especially if thread	1991	The default is probably ok in most situations, especially if thread
1506	creation is fast. If thread creation is very slow on your system you might	1992	creation is fast. If thread creation is very slow on your system you might
1507	want to use larger values.	1993	want to use larger values.
1508		1994
		1995	=item IO::AIO::idle_timeout $seconds
		1996
		1997	Sets the minimum idle timeout (default 10) after which worker threads are
		1998	allowed to exit. SEe C<IO::AIO::max_idle>.
		1999
1509	=item IO::AIO::max_outstanding $maxreqs	2000	=item IO::AIO::max_outstanding $maxreqs
		2001
		2002	Sets the maximum number of outstanding requests to C<$nreqs>. If
		2003	you do queue up more than this number of requests, the next call to
		2004	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		2005	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2006	longer exceeded.
		2007
		2008	In other words, this setting does not enforce a queue limit, but can be
		2009	used to make poll functions block if the limit is exceeded.
1510		2010
1511	This is a very bad function to use in interactive programs because it	2011	This is a very bad function to use in interactive programs because it
1512	blocks, and a bad way to reduce concurrency because it is inexact: Better	2012	blocks, and a bad way to reduce concurrency because it is inexact: Better
1513	use an C<aio_group> together with a feed callback.	2013	use an C<aio_group> together with a feed callback.
1514		2014
1515	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2015	Its main use is in scripts without an event loop - when you want to stat
1516	do queue up more than this number of requests, the next call to the	2016	a lot of files, you can write something like this:
1517	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1518	function will block until the limit is no longer exceeded.
1519		2017
1520	The default value is very large, so there is no practical limit on the	2018	IO::AIO::max_outstanding 32;
1521	number of outstanding requests.
1522		2019
1523	You can still queue as many requests as you want. Therefore,	2020	for my $path (...) {
1524	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2021	aio_stat $path , ...;
1525	as a stop gap to shield against fatal memory overflow (with large values).	2022	IO::AIO::poll_cb;
		2023	}
		2024
		2025	IO::AIO::flush;
		2026
		2027	The call to C<poll_cb> inside the loop will normally return instantly, but
		2028	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2029	some requests have been handled. This keeps the loop from pushing a large
		2030	number of C<aio_stat> requests onto the queue.
		2031
		2032	The default value for C<max_outstanding> is very large, so there is no
		2033	practical limit on the number of outstanding requests.
1526		2034
1527	=back	2035	=back
1528		2036
1529	=head3 STATISTICAL INFORMATION	2037	=head3 STATISTICAL INFORMATION
1530		2038
…		…
1552		2060
1553	=back	2061	=back
1554		2062
1555	=head3 MISCELLANEOUS FUNCTIONS	2063	=head3 MISCELLANEOUS FUNCTIONS
1556		2064
1557	IO::AIO implements some functions that might be useful, but are not	2065	IO::AIO implements some functions that are useful when you want to use
1558	asynchronous.	2066	some "Advanced I/O" function not available to in Perl, without going the
		2067	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2068	counterpart.
1559		2069
1560	=over 4	2070	=over 4
		2071
		2072	=item $numfd = IO::AIO::get_fdlimit
		2073
		2074	Tries to find the current file descriptor limit and returns it, or
		2075	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2076	the highest valid file descriptor number.
		2077
		2078	=item IO::AIO::min_fdlimit [$numfd]
		2079
		2080	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2081	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2082	is missing, it will try to set a very high limit, although this is not
		2083	recommended when you know the actual minimum that you require.
		2084
		2085	If the limit cannot be raised enough, the function makes a best-effort
		2086	attempt to increase the limit as much as possible, using various
		2087	tricks, while still failing. You can query the resulting limit using
		2088	C<IO::AIO::get_fdlimit>.
		2089
		2090	If an error occurs, returns C<undef> and sets C<$!>.
1561		2091
1562	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2092	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1563		2093
1564	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2094	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1565	but is blocking (this makes most sense if you know the input data is	2095	but is blocking (this makes most sense if you know the input data is
…		…
1568		2098
1569	Returns the number of bytes copied, or C<-1> on error.	2099	Returns the number of bytes copied, or C<-1> on error.
1570		2100
1571	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2101	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1572		2102
1573	Simply calls the C<posix_fadvise> function (see it's	2103	Simply calls the C<posix_fadvise> function (see its
1574	manpage for details). The following advice constants are	2104	manpage for details). The following advice constants are
1575	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2105	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1576	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2106	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1577	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2107	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1578		2108
1579	On systems that do not implement C<posix_fadvise>, this function returns	2109	On systems that do not implement C<posix_fadvise>, this function returns
1580	ENOSYS, otherwise the return value of C<posix_fadvise>.	2110	ENOSYS, otherwise the return value of C<posix_fadvise>.
1581		2111
		2112	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2113
		2114	Simply calls the C<posix_madvise> function (see its
		2115	manpage for details). The following advice constants are
		2116	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2117	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2118	C<IO::AIO::MADV_DONTNEED>.
		2119
		2120	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2121	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2122	will be reduced to fit into the C<$scalar>.
		2123
		2124	On systems that do not implement C<posix_madvise>, this function returns
		2125	ENOSYS, otherwise the return value of C<posix_madvise>.
		2126
		2127	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2128
		2129	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2130	$scalar (see its manpage for details). The following protect
		2131	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2132	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2133
		2134	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2135	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2136	will be reduced to fit into the C<$scalar>.
		2137
		2138	On systems that do not implement C<mprotect>, this function returns
		2139	ENOSYS, otherwise the return value of C<mprotect>.
		2140
1582	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2141	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1583		2142
1584	Memory-maps a file (or anonymous memory range) and attaches it to the	2143	Memory-maps a file (or anonymous memory range) and attaches it to the
1585	given C<$scalar>, which will act like a string scalar.	2144	given C<$scalar>, which will act like a string scalar. Returns true on
		2145	success, and false otherwise.
1586		2146
		2147	The scalar must exist, but its contents do not matter - this means you
		2148	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2149	the scalar first.
		2150
1587	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2151	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1588	change the string length, and most read-only operations such as copying it	2152	which don't change the string length, and most read-only operations such
1589	or searching it with regexes and so on.	2153	as copying it or searching it with regexes and so on.
1590		2154
1591	Anything else is unsafe and will, at best, result in memory leaks.	2155	Anything else is unsafe and will, at best, result in memory leaks.
1592		2156
1593	The memory map associated with the C<$scalar> is automatically removed	2157	The memory map associated with the C<$scalar> is automatically removed
1594	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2158	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1595	C<IO::AIO::munmap> functions are called.	2159	or C<IO::AIO::munmap> functions are called on it.
1596		2160
1597	This calls the C<mmap>(2) function internally. See your system's manual	2161	This calls the C<mmap>(2) function internally. See your system's manual
1598	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2162	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1599		2163
1600	The C<$length> must be larger than zero and smaller than the actual	2164	The C<$length> must be larger than zero and smaller than the actual
1601	filesize.	2165	filesize.
1602		2166
1603	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2167	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1604	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2168	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1605		2169
1606	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2170	C<$flags> can be a combination of
1607	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2171	C<IO::AIO::MAP_SHARED> or
1608	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2172	C<IO::AIO::MAP_PRIVATE>,
		2173	or a number of system-specific flags (when not available, the are C<0>):
1609	(which is set to C<MAP_ANON> if your system only provides this	2174	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1610	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2175	C<IO::AIO::MAP_LOCKED>,
1611	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2176	C<IO::AIO::MAP_NORESERVE>,
		2177	C<IO::AIO::MAP_POPULATE>,
1612	C<IO::AIO::MAP_NONBLOCK>	2178	C<IO::AIO::MAP_NONBLOCK>,
		2179	C<IO::AIO::MAP_FIXED>,
		2180	C<IO::AIO::MAP_GROWSDOWN>,
		2181	C<IO::AIO::MAP_32BIT>,
		2182	C<IO::AIO::MAP_HUGETLB> or
		2183	C<IO::AIO::MAP_STACK>.
1613		2184
1614	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2185	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1615		2186
1616	C<$offset> is the offset from the start of the file - it generally must be	2187	C<$offset> is the offset from the start of the file - it generally must be
1617	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2188	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1642		2213
1643	Calls the C<munlockall> function.	2214	Calls the C<munlockall> function.
1644		2215
1645	On systems that do not implement C<munlockall>, this function returns	2216	On systems that do not implement C<munlockall>, this function returns
1646	ENOSYS, otherwise the return value of C<munlockall>.	2217	ENOSYS, otherwise the return value of C<munlockall>.
		2218
		2219	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2220
		2221	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2222	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2223	should be the file offset.
		2224
		2225	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2226	silently corrupt the data in this case.
		2227
		2228	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2229	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2230	C<IO::AIO::SPLICE_F_GIFT>.
		2231
		2232	See the C<splice(2)> manpage for details.
		2233
		2234	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2235
		2236	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2237	description for C<IO::AIO::splice> above for details.
		2238
		2239	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2240
		2241	Attempts to query or change the pipe buffer size. Obviously works only
		2242	on pipes, and currently works only on GNU/Linux systems, and fails with
		2243	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2244	size on other systems, drop me a note.
		2245
		2246	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2247
		2248	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2249	C<$flags> is missing or C<0>, then this should be the same as a call to
		2250	perl's built-in C<pipe> function and create a new pipe, and works on
		2251	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2252	(..., 4096, O_BINARY)>.
		2253
		2254	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2255	the given flags (Linux 2.6.27, glibc 2.9).
		2256
		2257	On success, the read and write file handles are returned.
		2258
		2259	On error, nothing will be returned. If the pipe2 syscall is missing and
		2260	C<$flags> is non-zero, fails with C<ENOSYS>.
		2261
		2262	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2263	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2264	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1647		2265
1648	=back	2266	=back
1649		2267
1650	=cut	2268	=cut
1651		2269
…		…
1686	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2304	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1687	\&IO::AIO::poll_cb);	2305	\&IO::AIO::poll_cb);
1688		2306
1689	=head2 FORK BEHAVIOUR	2307	=head2 FORK BEHAVIOUR
1690		2308
1691	This module should do "the right thing" when the process using it forks:	2309	Usage of pthreads in a program changes the semantics of fork
		2310	considerably. Specifically, only async-safe functions can be called after
		2311	fork. Perl doesn't know about this, so in general, you cannot call fork
		2312	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2313	pthreads, so this applies, but many other extensions and (for inexplicable
		2314	reasons) perl itself often is linked against pthreads, so this limitation
		2315	applies to quite a lot of perls.
1692		2316
1693	Before the fork, IO::AIO enters a quiescent state where no requests	2317	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1694	can be added in other threads and no results will be processed. After	2318	only works in the process that loaded it. Forking is fully supported, but
1695	the fork the parent simply leaves the quiescent state and continues	2319	using IO::AIO in the child is not.
1696	request/result processing, while the child frees the request/result queue
1697	(so that the requests started before the fork will only be handled in the
1698	parent). Threads will be started on demand until the limit set in the
1699	parent process has been reached again.
1700		2320
1701	In short: the parent will, after a short pause, continue as if fork had	2321	You might get around by not I<using> IO::AIO before (or after)
1702	not been called, while the child will act as if IO::AIO has not been used	2322	forking. You could also try to call the L<IO::AIO::reinit> function in the
1703	yet.	2323	child:
		2324
		2325	=over 4
		2326
		2327	=item IO::AIO::reinit
		2328
		2329	Abandons all current requests and I/O threads and simply reinitialises all
		2330	data structures. This is not an operation supported by any standards, but
		2331	happens to work on GNU/Linux and some newer BSD systems.
		2332
		2333	The only reasonable use for this function is to call it after forking, if
		2334	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2335	the process will result in undefined behaviour. Calling it at any time
		2336	will also result in any undefined (by POSIX) behaviour.
		2337
		2338	=back
1704		2339
1705	=head2 MEMORY USAGE	2340	=head2 MEMORY USAGE
1706		2341
1707	Per-request usage:	2342	Per-request usage:
1708		2343

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