[ViewVC] Diff of: cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.195 by root, Fri May 27 19:56:31 2011 UTC vs.
Revision 1.270 by root, Fri Jun 23 03:23:19 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 = '3.9';	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 idle_timeout	192	min_parallel max_parallel max_idle idle_timeout
188	nreqs nready npending nthreads	193	nreqs nready npending nthreads
…		…
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->()
…		…
266	IO::AIO::nready	280	IO::AIO::nready
267	IO::AIO::npending	281	IO::AIO::npending
268		282
269	IO::AIO::sendfile $ofh, $ifh, $offset, $count	283	IO::AIO::sendfile $ofh, $ifh, $offset, $count
270	IO::AIO::fadvise $fh, $offset, $len, $advice	284	IO::AIO::fadvise $fh, $offset, $len, $advice
		285	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		286	IO::AIO::munmap $scalar
271	IO::AIO::madvise $scalar, $offset, $length, $advice	287	IO::AIO::madvise $scalar, $offset, $length, $advice
272	IO::AIO::mprotect $scalar, $offset, $length, $protect	288	IO::AIO::mprotect $scalar, $offset, $length, $protect
273	IO::AIO::munlock $scalar, $offset = 0, $length = undef	289	IO::AIO::munlock $scalar, $offset = 0, $length = undef
274	IO::AIO::munlockall	290	IO::AIO::munlockall
275		291
276	=head2 AIO REQUEST FUNCTIONS	292	=head2 API NOTES
277		293
278	All the C<aio_*> calls are more or less thin wrappers around the syscall	294	All the C<aio_*> calls are more or less thin wrappers around the syscall
279	with the same name (sans C<aio_>). The arguments are similar or identical,	295	with the same name (sans C<aio_>). The arguments are similar or identical,
280	and they all accept an additional (and optional) C<$callback> argument	296	and they all accept an additional (and optional) C<$callback> argument
281	which must be a code reference. This code reference will get called with	297	which must be a code reference. This code reference will be called after
282	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	298	the syscall has been executed in an asynchronous fashion. The results
283	perl, which usually delivers "false") as its sole argument after the given	299	of the request will be passed as arguments to the callback (and, if an
284	syscall has been executed asynchronously.	300	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		301	most syscalls return C<-1> on error, unlike perl, which usually delivers
		302	"false").
		303
		304	Some requests (such as C<aio_readdir>) pass the actual results and
		305	communicate failures by passing C<undef>.
285		306
286	All functions expecting a filehandle keep a copy of the filehandle	307	All functions expecting a filehandle keep a copy of the filehandle
287	internally until the request has finished.	308	internally until the request has finished.
288		309
289	All functions return request objects of type L<IO::AIO::REQ> that allow	310	All functions return request objects of type L<IO::AIO::REQ> that allow
290	further manipulation of those requests while they are in-flight.	311	further manipulation of those requests while they are in-flight.
291		312
292	The pathnames you pass to these routines I<must> be absolute and	313	The pathnames you pass to these routines I<should> be absolute. The
293	encoded as octets. The reason for the former is that at the time the	314	reason for this is that at the time the request is being executed, the
294	request is being executed, the current working directory could have	315	current working directory could have changed. Alternatively, you can
295	changed. Alternatively, you can make sure that you never change the	316	make sure that you never change the current working directory anywhere
296	current working directory anywhere in the program and then use relative	317	in the program and then use relative paths. You can also take advantage
297	paths.	318	of IO::AIOs working directory abstraction, that lets you specify paths
		319	relative to some previously-opened "working directory object" - see the
		320	description of the C<IO::AIO::WD> class later in this document.
298		321
299	To encode pathnames as octets, either make sure you either: a) always pass	322	To encode pathnames as octets, either make sure you either: a) always pass
300	in filenames you got from outside (command line, readdir etc.) without	323	in filenames you got from outside (command line, readdir etc.) without
301	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	324	tinkering, b) are in your native filesystem encoding, c) use the Encode
302	your pathnames to the locale (or other) encoding in effect in the user	325	module and encode your pathnames to the locale (or other) encoding in
303	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	326	effect in the user environment, d) use Glib::filename_from_unicode on
304	use something else to ensure your scalar has the correct contents.	327	unicode filenames or e) use something else to ensure your scalar has the
		328	correct contents.
305		329
306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	330	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
307	handles correctly whether it is set or not.	331	handles correctly whether it is set or not.
		332
		333	=head2 AIO REQUEST FUNCTIONS
308		334
309	=over 4	335	=over 4
310		336
311	=item $prev_pri = aioreq_pri [$pri]	337	=item $prev_pri = aioreq_pri [$pri]
312		338
…		…
342		368
343		369
344	=item aio_open $pathname, $flags, $mode, $callback->($fh)	370	=item aio_open $pathname, $flags, $mode, $callback->($fh)
345		371
346	Asynchronously open or create a file and call the callback with a newly	372	Asynchronously open or create a file and call the callback with a newly
347	created filehandle for the file.	373	created filehandle for the file (or C<undef> in case of an error).
348		374
349	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	375	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
350	for an explanation.	376	for an explanation.
351		377
352	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	378	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
375	following POSIX and non-POSIX constants are available (missing ones on	401	following POSIX and non-POSIX constants are available (missing ones on
376	your system are, as usual, C<0>):	402	your system are, as usual, C<0>):
377		403
378	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	404	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
379	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	405	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
380	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	406	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
381		407
382		408
383	=item aio_close $fh, $callback->($status)	409	=item aio_close $fh, $callback->($status)
384		410
385	Asynchronously close a file and call the callback with the result	411	Asynchronously close a file and call the callback with the result
…		…
395	Or in other words: the file descriptor will be closed, but it will not be	421	Or in other words: the file descriptor will be closed, but it will not be
396	free for reuse until the perl filehandle is closed.	422	free for reuse until the perl filehandle is closed.
397		423
398	=cut	424	=cut
399		425
		426	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		427
		428	Seeks the filehandle to the new C<$offset>, similarly to perl's
		429	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		430	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		431	C<IO::AIO::SEEK_END>).
		432
		433	The resulting absolute offset will be passed to the callback, or C<-1> in
		434	case of an error.
		435
		436	In theory, the C<$whence> constants could be different than the
		437	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		438	so don't panic.
		439
		440	As a GNU/Linux (and maybe Solaris) extension, also the constants
		441	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		442	could be found. No guarantees about suitability for use in C<aio_seek> or
		443	Perl's C<sysseek> can be made though, although I would naively assume they
		444	"just work".
		445
400	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	446	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
401		447
402	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	448	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
403		449
404	Reads or writes C<$length> bytes from or to the specified C<$fh> and	450	Reads or writes C<$length> bytes from or to the specified C<$fh> and
405	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	451	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
406	and calls the callback without the actual number of bytes read (or -1 on	452	calls the callback with the actual number of bytes transferred (or -1 on
407	error, just like the syscall).	453	error, just like the syscall).
408		454
409	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	455	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
410	offset plus the actual number of bytes read.	456	offset plus the actual number of bytes read.
411		457
…		…
436		482
437	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	483	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
438	reading at byte offset C<$in_offset>, and starts writing at the current	484	reading at byte offset C<$in_offset>, and starts writing at the current
439	file offset of C<$out_fh>. Because of that, it is not safe to issue more	485	file offset of C<$out_fh>. Because of that, it is not safe to issue more
440	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	486	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
441	other.	487	other. The same C<$in_fh> works fine though, as this function does not
		488	move or use the file offset of C<$in_fh>.
442		489
443	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than	490	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
444	are written, and there is no way to find out how many bytes have been read	491	are written, and there is no way to find out how many more bytes have been
445	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of	492	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
446	bytes written to C<$out_fh>. Only if the result value equals C<$length>	493	number of bytes written to C<$out_fh>. Only if the result value equals
447	one can assume that C<$length> bytes have been read.	494	C<$length> one can assume that C<$length> bytes have been read.
448		495
449	Unlike with other C<aio_> functions, it makes a lot of sense to use	496	Unlike with other C<aio_> functions, it makes a lot of sense to use
450	C<aio_sendfile> on non-blocking sockets, as long as one end (typically	497	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
451	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while	498	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
452	the socket I/O will be non-blocking. Note, however, that you can run into	499	the socket I/O will be non-blocking. Note, however, that you can run
453	a trap where C<aio_sendfile> reads some data with readahead, then fails	500	into a trap where C<aio_sendfile> reads some data with readahead, then
454	to write all data, and when the socket is ready the next time, the data	501	fails to write all data, and when the socket is ready the next time, the
455	in the cache is already lost, forcing C<aio_sendfile> to again hit the	502	data in the cache is already lost, forcing C<aio_sendfile> to again hit
456	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage	503	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
457	much better.	504	resource usage.
458		505
459	This call tries to make use of a native C<sendfile> syscall to provide	506	This call tries to make use of a native C<sendfile>-like syscall to
460	zero-copy operation. For this to work, C<$out_fh> should refer to a	507	provide zero-copy operation. For this to work, C<$out_fh> should refer to
461	socket, and C<$in_fh> should refer to an mmap'able file.	508	a socket, and C<$in_fh> should refer to an mmap'able file.
462		509
463	If a native sendfile cannot be found or it fails with C<ENOSYS>,	510	If a native sendfile cannot be found or it fails with C<ENOSYS>,
464	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	511	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
465	it will be emulated, so you can call C<aio_sendfile> on any type of	512	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
466	filehandle regardless of the limitations of the operating system.	513	type of filehandle regardless of the limitations of the operating system.
		514
		515	As native sendfile syscalls (as practically any non-POSIX interface hacked
		516	together in a hurry to improve benchmark numbers) tend to be rather buggy
		517	on many systems, this implementation tries to work around some known bugs
		518	in Linux and FreeBSD kernels (probably others, too), but that might fail,
		519	so you really really should check the return value of C<aio_sendfile> -
		520	fewer bytes than expected might have been transferred.
467		521
468		522
469	=item aio_readahead $fh,$offset,$length, $callback->($retval)	523	=item aio_readahead $fh,$offset,$length, $callback->($retval)
470		524
471	C<aio_readahead> populates the page cache with data from a file so that	525	C<aio_readahead> populates the page cache with data from a file so that
…		…
475	whole pages, so that offset is effectively rounded down to a page boundary	529	whole pages, so that offset is effectively rounded down to a page boundary
476	and bytes are read up to the next page boundary greater than or equal to	530	and bytes are read up to the next page boundary greater than or equal to
477	(off-set+length). C<aio_readahead> does not read beyond the end of the	531	(off-set+length). C<aio_readahead> does not read beyond the end of the
478	file. The current file offset of the file is left unchanged.	532	file. The current file offset of the file is left unchanged.
479		533
480	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	534	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
481	emulated by simply reading the data, which would have a similar effect.	535	be emulated by simply reading the data, which would have a similar effect.
482		536
483		537
484	=item aio_stat $fh_or_path, $callback->($status)	538	=item aio_stat $fh_or_path, $callback->($status)
485		539
486	=item aio_lstat $fh, $callback->($status)	540	=item aio_lstat $fh, $callback->($status)
…		…
555	namemax => 255,	609	namemax => 255,
556	frsize => 1024,	610	frsize => 1024,
557	fsid => 1810	611	fsid => 1810
558	}	612	}
559		613
		614	Here is a (likely partial - send me updates!) list of fsid values used by
		615	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		616
		617	0x0000adf5 adfs
		618	0x0000adff affs
		619	0x5346414f afs
		620	0x09041934 anon-inode filesystem
		621	0x00000187 autofs
		622	0x42465331 befs
		623	0x1badface bfs
		624	0x42494e4d binfmt_misc
		625	0x9123683e btrfs
		626	0x0027e0eb cgroupfs
		627	0xff534d42 cifs
		628	0x73757245 coda
		629	0x012ff7b7 coh
		630	0x28cd3d45 cramfs
		631	0x453dcd28 cramfs-wend (wrong endianness)
		632	0x64626720 debugfs
		633	0x00001373 devfs
		634	0x00001cd1 devpts
		635	0x0000f15f ecryptfs
		636	0x00414a53 efs
		637	0x0000137d ext
		638	0x0000ef53 ext2/ext3/ext4
		639	0x0000ef51 ext2
		640	0xf2f52010 f2fs
		641	0x00004006 fat
		642	0x65735546 fuseblk
		643	0x65735543 fusectl
		644	0x0bad1dea futexfs
		645	0x01161970 gfs2
		646	0x47504653 gpfs
		647	0x00004244 hfs
		648	0xf995e849 hpfs
		649	0x00c0ffee hostfs
		650	0x958458f6 hugetlbfs
		651	0x2bad1dea inotifyfs
		652	0x00009660 isofs
		653	0x000072b6 jffs2
		654	0x3153464a jfs
		655	0x6b414653 k-afs
		656	0x0bd00bd0 lustre
		657	0x0000137f minix
		658	0x0000138f minix 30 char names
		659	0x00002468 minix v2
		660	0x00002478 minix v2 30 char names
		661	0x00004d5a minix v3
		662	0x19800202 mqueue
		663	0x00004d44 msdos
		664	0x0000564c novell
		665	0x00006969 nfs
		666	0x6e667364 nfsd
		667	0x00003434 nilfs
		668	0x5346544e ntfs
		669	0x00009fa1 openprom
		670	0x7461636F ocfs2
		671	0x00009fa0 proc
		672	0x6165676c pstorefs
		673	0x0000002f qnx4
		674	0x68191122 qnx6
		675	0x858458f6 ramfs
		676	0x52654973 reiserfs
		677	0x00007275 romfs
		678	0x67596969 rpc_pipefs
		679	0x73636673 securityfs
		680	0xf97cff8c selinux
		681	0x0000517b smb
		682	0x534f434b sockfs
		683	0x73717368 squashfs
		684	0x62656572 sysfs
		685	0x012ff7b6 sysv2
		686	0x012ff7b5 sysv4
		687	0x01021994 tmpfs
		688	0x15013346 udf
		689	0x00011954 ufs
		690	0x54190100 ufs byteswapped
		691	0x00009fa2 usbdevfs
		692	0x01021997 v9fs
		693	0xa501fcf5 vxfs
		694	0xabba1974 xenfs
		695	0x012ff7b4 xenix
		696	0x58465342 xfs
		697	0x012fd16d xia
560		698
561	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	699	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
562		700
563	Works like perl's C<utime> function (including the special case of $atime	701	Works like perl's C<utime> function (including the special case of $atime
564	and $mtime being undef). Fractional times are supported if the underlying	702	and $mtime being undef). Fractional times are supported if the underlying
…		…
592	=item aio_truncate $fh_or_path, $offset, $callback->($status)	730	=item aio_truncate $fh_or_path, $offset, $callback->($status)
593		731
594	Works like truncate(2) or ftruncate(2).	732	Works like truncate(2) or ftruncate(2).
595		733
596		734
		735	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		736
		737	Allocates or frees disk space according to the C<$mode> argument. See the
		738	linux C<fallocate> documentation for details.
		739
		740	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		741	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE \| IO::AIO::FALLOC_FL_KEEP_SIZE>,
		742	to deallocate a file range.
		743
		744	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		745	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		746	your L<fallocate(2)> manpage).
		747
		748	The file system block size used by C<fallocate> is presumably the
		749	C<f_bsize> returned by C<statvfs>.
		750
		751	If C<fallocate> isn't available or cannot be emulated (currently no
		752	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		753
		754
597	=item aio_chmod $fh_or_path, $mode, $callback->($status)	755	=item aio_chmod $fh_or_path, $mode, $callback->($status)
598		756
599	Works like perl's C<chmod> function.	757	Works like perl's C<chmod> function.
600		758
601		759
…		…
603		761
604	Asynchronously unlink (delete) a file and call the callback with the	762	Asynchronously unlink (delete) a file and call the callback with the
605	result code.	763	result code.
606		764
607		765
608	=item aio_mknod $path, $mode, $dev, $callback->($status)	766	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
609		767
610	[EXPERIMENTAL]	768	[EXPERIMENTAL]
611		769
612	Asynchronously create a device node (or fifo). See mknod(2).	770	Asynchronously create a device node (or fifo). See mknod(2).
613		771
614	The only (POSIX-) portable way of calling this function is:	772	The only (POSIX-) portable way of calling this function is:
615		773
616	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	774	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
617		775
618	See C<aio_stat> for info about some potentially helpful extra constants	776	See C<aio_stat> for info about some potentially helpful extra constants
619	and functions.	777	and functions.
620		778
621	=item aio_link $srcpath, $dstpath, $callback->($status)	779	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
628		786
629	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	787	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
630	the path C<$dstpath> and call the callback with the result code.	788	the path C<$dstpath> and call the callback with the result code.
631		789
632		790
633	=item aio_readlink $path, $callback->($link)	791	=item aio_readlink $pathname, $callback->($link)
634		792
635	Asynchronously read the symlink specified by C<$path> and pass it to	793	Asynchronously read the symlink specified by C<$path> and pass it to
636	the callback. If an error occurs, nothing or undef gets passed to the	794	the callback. If an error occurs, nothing or undef gets passed to the
637	callback.	795	callback.
638		796
639		797
		798	=item aio_realpath $pathname, $callback->($path)
		799
		800	Asynchronously make the path absolute and resolve any symlinks in
		801	C<$path>. The resulting path only consists of directories (same as
		802	L<Cwd::realpath>).
		803
		804	This request can be used to get the absolute path of the current working
		805	directory by passing it a path of F<.> (a single dot).
		806
		807
640	=item aio_rename $srcpath, $dstpath, $callback->($status)	808	=item aio_rename $srcpath, $dstpath, $callback->($status)
641		809
642	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	810	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
643	rename(2) and call the callback with the result code.	811	rename(2) and call the callback with the result code.
		812
		813	On systems that support the AIO::WD working directory abstraction
		814	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		815	of failing, C<rename> is called on the absolute path of C<$wd>.
		816
		817
		818	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		819
		820	Basically a version of C<aio_rename> with an additional C<$flags>
		821	argument. Calling this with C<$flags=0> is the same as calling
		822	C<aio_rename>.
		823
		824	Non-zero flags are currently only supported on GNU/Linux systems that
		825	support renameat2. Other systems fail with C<ENOSYS> in this case.
		826
		827	The following constants are available (missing ones are, as usual C<0>),
		828	see renameat2(2) for details:
		829
		830	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		831	and C<IO::AIO::RENAME_WHITEOUT>.
644		832
645		833
646	=item aio_mkdir $pathname, $mode, $callback->($status)	834	=item aio_mkdir $pathname, $mode, $callback->($status)
647		835
648	Asynchronously mkdir (create) a directory and call the callback with	836	Asynchronously mkdir (create) a directory and call the callback with
…		…
653	=item aio_rmdir $pathname, $callback->($status)	841	=item aio_rmdir $pathname, $callback->($status)
654		842
655	Asynchronously rmdir (delete) a directory and call the callback with the	843	Asynchronously rmdir (delete) a directory and call the callback with the
656	result code.	844	result code.
657		845
		846	On systems that support the AIO::WD working directory abstraction
		847	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		848	C<rmdir> is called on the absolute path of C<$wd>.
		849
658		850
659	=item aio_readdir $pathname, $callback->($entries)	851	=item aio_readdir $pathname, $callback->($entries)
660		852
661	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	853	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
662	directory (i.e. opendir + readdir + closedir). The entries will not be	854	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
666	array-ref with the filenames.	858	array-ref with the filenames.
667		859
668		860
669	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	861	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
670		862
671	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	863	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
672	behaviour and output format. In case of an error, C<$entries> will be	864	tune behaviour and output format. In case of an error, C<$entries> will be
673	C<undef>.	865	C<undef>.
674		866
675	The flags are a combination of the following constants, ORed together (the	867	The flags are a combination of the following constants, ORed together (the
676	flags will also be passed to the callback, possibly modified):	868	flags will also be passed to the callback, possibly modified):
677		869
…		…
724		916
725	=item IO::AIO::READDIR_FOUND_UNKNOWN	917	=item IO::AIO::READDIR_FOUND_UNKNOWN
726		918
727	This flag should not be set when calling C<aio_readdirx>. Instead, it	919	This flag should not be set when calling C<aio_readdirx>. Instead, it
728	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	920	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
729	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	921	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
730	C<$type>'s are known, which can be used to speed up some algorithms.	922	C<$type>'s are known, which can be used to speed up some algorithms.
731		923
732	=back	924	=back
733		925
734		926
735	=item aio_load $path, $data, $callback->($status)	927	=item aio_load $pathname, $data, $callback->($status)
736		928
737	This is a composite request that tries to fully load the given file into	929	This is a composite request that tries to fully load the given file into
738	memory. Status is the same as with aio_read.	930	memory. Status is the same as with aio_read.
739		931
740	=cut	932	=cut
…		…
862	if ($_[0] && $! == EXDEV) {	1054	if ($_[0] && $! == EXDEV) {
863	aioreq_pri $pri;	1055	aioreq_pri $pri;
864	add $grp aio_copy $src, $dst, sub {	1056	add $grp aio_copy $src, $dst, sub {
865	$grp->result ($_[0]);	1057	$grp->result ($_[0]);
866		1058
867	if (!$_[0]) {	1059	unless ($_[0]) {
868	aioreq_pri $pri;	1060	aioreq_pri $pri;
869	add $grp aio_unlink $src;	1061	add $grp aio_unlink $src;
870	}	1062	}
871	};	1063	};
872	} else {	1064	} else {
…		…
875	};	1067	};
876		1068
877	$grp	1069	$grp
878	}	1070	}
879		1071
880	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1072	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
881		1073
882	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1074	Scans a directory (similar to C<aio_readdir>) but additionally tries to
883	efficiently separate the entries of directory C<$path> into two sets of	1075	efficiently separate the entries of directory C<$path> into two sets of
884	names, directories you can recurse into (directories), and ones you cannot	1076	names, directories you can recurse into (directories), and ones you cannot
885	recurse into (everything else, including symlinks to directories).	1077	recurse into (everything else, including symlinks to directories).
…		…
916	Then entries will be sorted into likely directories a non-initial dot	1108	Then entries will be sorted into likely directories a non-initial dot
917	currently) and likely non-directories (see C<aio_readdirx>). Then every	1109	currently) and likely non-directories (see C<aio_readdirx>). Then every
918	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1110	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
919	in order of their inode numbers. If that succeeds, it assumes that the	1111	in order of their inode numbers. If that succeeds, it assumes that the
920	entry is a directory or a symlink to directory (which will be checked	1112	entry is a directory or a symlink to directory (which will be checked
921	seperately). This is often faster than stat'ing the entry itself because	1113	separately). This is often faster than stat'ing the entry itself because
922	filesystems might detect the type of the entry without reading the inode	1114	filesystems might detect the type of the entry without reading the inode
923	data (e.g. ext2fs filetype feature), even on systems that cannot return	1115	data (e.g. ext2fs filetype feature), even on systems that cannot return
924	the filetype information on readdir.	1116	the filetype information on readdir.
925		1117
926	If the known number of directories (link count - 2) has been reached, the	1118	If the known number of directories (link count - 2) has been reached, the
…		…
942		1134
943	my $grp = aio_group $cb;	1135	my $grp = aio_group $cb;
944		1136
945	$maxreq = 4 if $maxreq <= 0;	1137	$maxreq = 4 if $maxreq <= 0;
946		1138
947	# stat once	1139	# get a wd object
948	aioreq_pri $pri;	1140	aioreq_pri $pri;
949	add $grp aio_stat $path, sub {	1141	add $grp aio_wd $path, sub {
		1142	$_[0]
950	return $grp->result () if $_[0];	1143	or return $grp->result ();
951	my $now = time;
952	my $hash1 = join ":", (stat _)[0,1,3,7,9];
953		1144
954	# read the directory entries	1145	my $wd = [shift, "."];
		1146
		1147	# stat once
955	aioreq_pri $pri;	1148	aioreq_pri $pri;
956	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1149	add $grp aio_stat $wd, sub {
957	my $entries = shift
958	or return $grp->result ();	1150	return $grp->result () if $_[0];
		1151	my $now = time;
		1152	my $hash1 = join ":", (stat _)[0,1,3,7,9];
959		1153
960	# stat the dir another time	1154	# read the directory entries
961	aioreq_pri $pri;	1155	aioreq_pri $pri;
		1156	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1157	my $entries = shift
		1158	or return $grp->result ();
		1159
		1160	# stat the dir another time
		1161	aioreq_pri $pri;
962	add $grp aio_stat $path, sub {	1162	add $grp aio_stat $wd, sub {
963	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1163	my $hash2 = join ":", (stat _)[0,1,3,7,9];
964		1164
965	my $ndirs;	1165	my $ndirs;
966		1166
967	# take the slow route if anything looks fishy	1167	# take the slow route if anything looks fishy
968	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1168	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
969	$ndirs = -1;	1169	$ndirs = -1;
970	} else {	1170	} else {
971	# if nlink == 2, we are finished	1171	# if nlink == 2, we are finished
972	# for non-posix-fs's, we rely on nlink < 2	1172	# for non-posix-fs's, we rely on nlink < 2
973	$ndirs = (stat _)[3] - 2	1173	$ndirs = (stat _)[3] - 2
974	or return $grp->result ([], $entries);	1174	or return $grp->result ([], $entries);
975	}	1175	}
976		1176
977	my (@dirs, @nondirs);	1177	my (@dirs, @nondirs);
978		1178
979	my $statgrp = add $grp aio_group sub {	1179	my $statgrp = add $grp aio_group sub {
980	$grp->result (\@dirs, \@nondirs);	1180	$grp->result (\@dirs, \@nondirs);
981	};	1181	};
982		1182
983	limit $statgrp $maxreq;	1183	limit $statgrp $maxreq;
984	feed $statgrp sub {	1184	feed $statgrp sub {
985	return unless @$entries;	1185	return unless @$entries;
986	my $entry = shift @$entries;	1186	my $entry = shift @$entries;
987		1187
988	aioreq_pri $pri;	1188	aioreq_pri $pri;
		1189	$wd->[1] = "$entry/.";
989	add $statgrp aio_stat "$path/$entry/.", sub {	1190	add $statgrp aio_stat $wd, sub {
990	if ($_[0] < 0) {	1191	if ($_[0] < 0) {
991	push @nondirs, $entry;	1192	push @nondirs, $entry;
992	} else {	1193	} else {
993	# need to check for real directory	1194	# need to check for real directory
994	aioreq_pri $pri;	1195	aioreq_pri $pri;
		1196	$wd->[1] = $entry;
995	add $statgrp aio_lstat "$path/$entry", sub {	1197	add $statgrp aio_lstat $wd, sub {
996	if (-d _) {	1198	if (-d _) {
997	push @dirs, $entry;	1199	push @dirs, $entry;
998		1200
999	unless (--$ndirs) {	1201	unless (--$ndirs) {
1000	push @nondirs, @$entries;	1202	push @nondirs, @$entries;
1001	feed $statgrp;	1203	feed $statgrp;
		1204	}
		1205	} else {
		1206	push @nondirs, $entry;
1002	}	1207	}
1003	} else {
1004	push @nondirs, $entry;
1005	}	1208	}
1006	}	1209	}
1007	}	1210	};
1008	};	1211	};
1009	};	1212	};
1010	};	1213	};
1011	};	1214	};
1012	};	1215	};
1013		1216
1014	$grp	1217	$grp
1015	}	1218	}
1016		1219
1017	=item aio_rmtree $path, $callback->($status)	1220	=item aio_rmtree $pathname, $callback->($status)
1018		1221
1019	Delete a directory tree starting (and including) C<$path>, return the	1222	Delete a directory tree starting (and including) C<$path>, return the
1020	status of the final C<rmdir> only. This is a composite request that	1223	status of the final C<rmdir> only. This is a composite request that
1021	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1224	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1022	everything else.	1225	everything else.
1023		1226
1024	=cut	1227	=cut
1025		1228
…		…
1047	};	1250	};
1048		1251
1049	$grp	1252	$grp
1050	}	1253	}
1051		1254
		1255	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1256
		1257	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1258
		1259	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1260	they execute asynchronously and pass the return value to the callback.
		1261
		1262	Both calls can be used for a lot of things, some of which make more sense
		1263	to run asynchronously in their own thread, while some others make less
		1264	sense. For example, calls that block waiting for external events, such
		1265	as locking, will also lock down an I/O thread while it is waiting, which
		1266	can deadlock the whole I/O system. At the same time, there might be no
		1267	alternative to using a thread to wait.
		1268
		1269	So in general, you should only use these calls for things that do
		1270	(filesystem) I/O, not for things that wait for other events (network,
		1271	other processes), although if you are careful and know what you are doing,
		1272	you still can.
		1273
		1274	The following constants are available (missing ones are, as usual C<0>):
		1275
		1276	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1277
		1278	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1279	C<FS_IOC_FIEMAP>.
		1280
		1281	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1282	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1283
		1284	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1285	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1286	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1287	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1288	C<FS_FL_USER_MODIFIABLE>.
		1289
		1290	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1291	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1292	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1293	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1294
1052	=item aio_sync $callback->($status)	1295	=item aio_sync $callback->($status)
1053		1296
1054	Asynchronously call sync and call the callback when finished.	1297	Asynchronously call sync and call the callback when finished.
1055		1298
1056	=item aio_fsync $fh, $callback->($status)	1299	=item aio_fsync $fh, $callback->($status)
…		…
1063	Asynchronously call fdatasync on the given filehandle and call the	1306	Asynchronously call fdatasync on the given filehandle and call the
1064	callback with the fdatasync result code.	1307	callback with the fdatasync result code.
1065		1308
1066	If this call isn't available because your OS lacks it or it couldn't be	1309	If this call isn't available because your OS lacks it or it couldn't be
1067	detected, it will be emulated by calling C<fsync> instead.	1310	detected, it will be emulated by calling C<fsync> instead.
		1311
		1312	=item aio_syncfs $fh, $callback->($status)
		1313
		1314	Asynchronously call the syncfs syscall to sync the filesystem associated
		1315	to the given filehandle and call the callback with the syncfs result
		1316	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1317	errno to C<ENOSYS> nevertheless.
1068		1318
1069	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1319	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1070		1320
1071	Sync the data portion of the file specified by C<$offset> and C<$length>	1321	Sync the data portion of the file specified by C<$offset> and C<$length>
1072	to disk (but NOT the metadata), by calling the Linux-specific	1322	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1076	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1326	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1077	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1327	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1078	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1328	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1079	manpage for details.	1329	manpage for details.
1080		1330
1081	=item aio_pathsync $path, $callback->($status)	1331	=item aio_pathsync $pathname, $callback->($status)
1082		1332
1083	This request tries to open, fsync and close the given path. This is a	1333	This request tries to open, fsync and close the given path. This is a
1084	composite request intended to sync directories after directory operations	1334	composite request intended to sync directories after directory operations
1085	(E.g. rename). This might not work on all operating systems or have any	1335	(E.g. rename). This might not work on all operating systems or have any
1086	specific effect, but usually it makes sure that directory changes get	1336	specific effect, but usually it makes sure that directory changes get
…		…
1117	};	1367	};
1118		1368
1119	$grp	1369	$grp
1120	}	1370	}
1121		1371
1122	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1372	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1123		1373
1124	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1374	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1125	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1375	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1126	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1376	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1127	scalar must only be modified in-place while an aio operation is pending on	1377	scalar must only be modified in-place while an aio operation is pending on
…		…
1129		1379
1130	It calls the C<msync> function of your OS, if available, with the memory	1380	It calls the C<msync> function of your OS, if available, with the memory
1131	area starting at C<$offset> in the string and ending C<$length> bytes	1381	area starting at C<$offset> in the string and ending C<$length> bytes
1132	later. If C<$length> is negative, counts from the end, and if C<$length>	1382	later. If C<$length> is negative, counts from the end, and if C<$length>
1133	is C<undef>, then it goes till the end of the string. The flags can be	1383	is C<undef>, then it goes till the end of the string. The flags can be
1134	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1384	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1135	C<IO::AIO::MS_SYNC>.	1385	C<IO::AIO::MS_INVALIDATE>.
1136		1386
1137	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1387	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1138		1388
1139	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1389	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1140	scalars.	1390	scalars.
1141		1391
1142	It touches (reads or writes) all memory pages in the specified	1392	It touches (reads or writes) all memory pages in the specified
1143	range inside the scalar. All caveats and parameters are the same	1393	range inside the scalar. All caveats and parameters are the same
1144	as for C<aio_msync>, above, except for flags, which must be either	1394	as for C<aio_msync>, above, except for flags, which must be either
1145	C<0> (which reads all pages and ensures they are instantiated) or	1395	C<0> (which reads all pages and ensures they are instantiated) or
1146	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1396	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1147	writing an octet from it, which dirties the page).	1397	writing an octet from it, which dirties the page).
1148		1398
1149	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1399	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1150		1400
1151	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1401	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1182	documented under L<MISCELLANEOUS FUNCTIONS>.	1432	documented under L<MISCELLANEOUS FUNCTIONS>.
1183		1433
1184	Example: asynchronously lock all current and future pages into memory.	1434	Example: asynchronously lock all current and future pages into memory.
1185		1435
1186	aio_mlockall IO::AIO::MCL_FUTURE;	1436	aio_mlockall IO::AIO::MCL_FUTURE;
		1437
		1438	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1439
		1440	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1441	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1442	the ioctl is not available on your OS, then this request will fail with
		1443	C<ENOSYS>.
		1444
		1445	C<$start> is the starting offset to query extents for, C<$length> is the
		1446	size of the range to query - if it is C<undef>, then the whole file will
		1447	be queried.
		1448
		1449	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1450	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1451	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1452	the data portion.
		1453
		1454	C<$count> is the maximum number of extent records to return. If it is
		1455	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1456	case, if it is C<0>, then the callback receives the number of extents
		1457	instead of the extents themselves (which is unreliable, see below).
		1458
		1459	If an error occurs, the callback receives no arguments. The special
		1460	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1461
		1462	Otherwise, the callback receives an array reference with extent
		1463	structures. Each extent structure is an array reference itself, with the
		1464	following members:
		1465
		1466	[$logical, $physical, $length, $flags]
		1467
		1468	Flags is any combination of the following flag values (typically either C<0>
		1469	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1470
		1471	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1472	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1473	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1474	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1475	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1476	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1477
		1478	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1479	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1480	it to return all extents of a range for files with large number of
		1481	extents. The code works around all these issues if C<$count> is undef.
1187		1482
1188	=item aio_group $callback->(...)	1483	=item aio_group $callback->(...)
1189		1484
1190	This is a very special aio request: Instead of doing something, it is a	1485	This is a very special aio request: Instead of doing something, it is a
1191	container for other aio requests, which is useful if you want to bundle	1486	container for other aio requests, which is useful if you want to bundle
…		…
1228	like sleep and file handle readable/writable, the overhead this creates is	1523	like sleep and file handle readable/writable, the overhead this creates is
1229	immense (it blocks a thread for a long time) so do not use this function	1524	immense (it blocks a thread for a long time) so do not use this function
1230	except to put your application under artificial I/O pressure.	1525	except to put your application under artificial I/O pressure.
1231		1526
1232	=back	1527	=back
		1528
		1529
		1530	=head2 IO::AIO::WD - multiple working directories
		1531
		1532	Your process only has one current working directory, which is used by all
		1533	threads. This makes it hard to use relative paths (some other component
		1534	could call C<chdir> at any time, and it is hard to control when the path
		1535	will be used by IO::AIO).
		1536
		1537	One solution for this is to always use absolute paths. This usually works,
		1538	but can be quite slow (the kernel has to walk the whole path on every
		1539	access), and can also be a hassle to implement.
		1540
		1541	Newer POSIX systems have a number of functions (openat, fdopendir,
		1542	futimensat and so on) that make it possible to specify working directories
		1543	per operation.
		1544
		1545	For portability, and because the clowns who "designed", or shall I write,
		1546	perpetrated this new interface were obviously half-drunk, this abstraction
		1547	cannot be perfect, though.
		1548
		1549	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1550	object. This object stores the canonicalised, absolute version of the
		1551	path, and on systems that allow it, also a directory file descriptor.
		1552
		1553	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1554	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1555	object and a pathname instead (or the IO::AIO::WD object alone, which
		1556	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1557	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1558	to that IO::AIO::WD object.
		1559
		1560	For example, to get a wd object for F</etc> and then stat F<passwd>
		1561	inside, you would write:
		1562
		1563	aio_wd "/etc", sub {
		1564	my $etcdir = shift;
		1565
		1566	# although $etcdir can be undef on error, there is generally no reason
		1567	# to check for errors here, as aio_stat will fail with ENOENT
		1568	# when $etcdir is undef.
		1569
		1570	aio_stat [$etcdir, "passwd"], sub {
		1571	# yay
		1572	};
		1573	};
		1574
		1575	The fact that C<aio_wd> is a request and not a normal function shows that
		1576	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1577	which is why it is done asynchronously.
		1578
		1579	To stat the directory obtained with C<aio_wd> above, one could write
		1580	either of the following three request calls:
		1581
		1582	aio_lstat "/etc" , sub { ... # pathname as normal string
		1583	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1584	aio_lstat $wd , sub { ... # shorthand for the previous
		1585
		1586	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1587	object and the pathname string, so you could write the following without
		1588	causing any issues due to C<$path> getting reused:
		1589
		1590	my $path = [$wd, undef];
		1591
		1592	for my $name (qw(abc def ghi)) {
		1593	$path->[1] = $name;
		1594	aio_stat $path, sub {
		1595	# ...
		1596	};
		1597	}
		1598
		1599	There are some caveats: when directories get renamed (or deleted), the
		1600	pathname string doesn't change, so will point to the new directory (or
		1601	nowhere at all), while the directory fd, if available on the system,
		1602	will still point to the original directory. Most functions accepting a
		1603	pathname will use the directory fd on newer systems, and the string on
		1604	older systems. Some functions (such as realpath) will always rely on the
		1605	string form of the pathname.
		1606
		1607	So this functionality is mainly useful to get some protection against
		1608	C<chdir>, to easily get an absolute path out of a relative path for future
		1609	reference, and to speed up doing many operations in the same directory
		1610	(e.g. when stat'ing all files in a directory).
		1611
		1612	The following functions implement this working directory abstraction:
		1613
		1614	=over 4
		1615
		1616	=item aio_wd $pathname, $callback->($wd)
		1617
		1618	Asynchonously canonicalise the given pathname and convert it to an
		1619	IO::AIO::WD object representing it. If possible and supported on the
		1620	system, also open a directory fd to speed up pathname resolution relative
		1621	to this working directory.
		1622
		1623	If something goes wrong, then C<undef> is passwd to the callback instead
		1624	of a working directory object and C<$!> is set appropriately. Since
		1625	passing C<undef> as working directory component of a pathname fails the
		1626	request with C<ENOENT>, there is often no need for error checking in the
		1627	C<aio_wd> callback, as future requests using the value will fail in the
		1628	expected way.
		1629
		1630	=item IO::AIO::CWD
		1631
		1632	This is a compiletime constant (object) that represents the process
		1633	current working directory.
		1634
		1635	Specifying this object as working directory object for a pathname is as if
		1636	the pathname would be specified directly, without a directory object. For
		1637	example, these calls are functionally identical:
		1638
		1639	aio_stat "somefile", sub { ... };
		1640	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1641
		1642	=back
		1643
		1644	To recover the path associated with an IO::AIO::WD object, you can use
		1645	C<aio_realpath>:
		1646
		1647	aio_realpath $wd, sub {
		1648	warn "path is $_[0]\n";
		1649	};
		1650
		1651	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1652	sometimes, fall back to using an absolue path.
1233		1653
1234	=head2 IO::AIO::REQ CLASS	1654	=head2 IO::AIO::REQ CLASS
1235		1655
1236	All non-aggregate C<aio_*> functions return an object of this class when	1656	All non-aggregate C<aio_*> functions return an object of this class when
1237	called in non-void context.	1657	called in non-void context.
…		…
1355		1775
1356	Sets a feeder/generator on this group: every group can have an attached	1776	Sets a feeder/generator on this group: every group can have an attached
1357	generator that generates requests if idle. The idea behind this is that,	1777	generator that generates requests if idle. The idea behind this is that,
1358	although you could just queue as many requests as you want in a group,	1778	although you could just queue as many requests as you want in a group,
1359	this might starve other requests for a potentially long time. For example,	1779	this might starve other requests for a potentially long time. For example,
1360	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1780	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1361	delaying any later requests for a long time.	1781	requests, delaying any later requests for a long time.
1362		1782
1363	To avoid this, and allow incremental generation of requests, you can	1783	To avoid this, and allow incremental generation of requests, you can
1364	instead a group and set a feeder on it that generates those requests. The	1784	instead a group and set a feeder on it that generates those requests. The
1365	feed callback will be called whenever there are few enough (see C<limit>,	1785	feed callback will be called whenever there are few enough (see C<limit>,
1366	below) requests active in the group itself and is expected to queue more	1786	below) requests active in the group itself and is expected to queue more
…		…
1415		1835
1416	See C<poll_cb> for an example.	1836	See C<poll_cb> for an example.
1417		1837
1418	=item IO::AIO::poll_cb	1838	=item IO::AIO::poll_cb
1419		1839
1420	Process some outstanding events on the result pipe. You have to call	1840	Process some requests that have reached the result phase (i.e. they have
		1841	been executed but the results are not yet reported). You have to call
		1842	this "regularly" to finish outstanding requests.
		1843
1421	this regularly. Returns C<0> if all events could be processed (or there	1844	Returns C<0> if all events could be processed (or there were no
1422	were no events to process), or C<-1> if it returned earlier for whatever	1845	events to process), or C<-1> if it returned earlier for whatever
1423	reason. Returns immediately when no events are outstanding. The amount of	1846	reason. Returns immediately when no events are outstanding. The amount
1424	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1847	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1425	C<IO::AIO::max_poll_time>.	1848	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1426		1849
1427	If not all requests were processed for whatever reason, the filehandle	1850	If not all requests were processed for whatever reason, the poll file
1428	will still be ready when C<poll_cb> returns, so normally you don't have to	1851	descriptor will still be ready when C<poll_cb> returns, so normally you
1429	do anything special to have it called later.	1852	don't have to do anything special to have it called later.
1430		1853
1431	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1854	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1432	ready, it can be beneficial to call this function from loops which submit	1855	ready, it can be beneficial to call this function from loops which submit
1433	a lot of requests, to make sure the results get processed when they become	1856	a lot of requests, to make sure the results get processed when they become
1434	available and not just when the loop is finished and the event loop takes	1857	available and not just when the loop is finished and the event loop takes
…		…
1443	poll => 'r', async => 1,	1866	poll => 'r', async => 1,
1444	cb => \&IO::AIO::poll_cb);	1867	cb => \&IO::AIO::poll_cb);
1445		1868
1446	=item IO::AIO::poll_wait	1869	=item IO::AIO::poll_wait
1447		1870
1448	If there are any outstanding requests and none of them in the result	1871	Wait until either at least one request is in the result phase or no
1449	phase, wait till the result filehandle becomes ready for reading (simply	1872	requests are outstanding anymore.
1450	does a C<select> on the filehandle. This is useful if you want to	1873
1451	synchronously wait for some requests to finish).	1874	This is useful if you want to synchronously wait for some requests to
		1875	become ready, without actually handling them.
1452		1876
1453	See C<nreqs> for an example.	1877	See C<nreqs> for an example.
1454		1878
1455	=item IO::AIO::poll	1879	=item IO::AIO::poll
1456		1880
…		…
1577		2001
1578	This is a very bad function to use in interactive programs because it	2002	This is a very bad function to use in interactive programs because it
1579	blocks, and a bad way to reduce concurrency because it is inexact: Better	2003	blocks, and a bad way to reduce concurrency because it is inexact: Better
1580	use an C<aio_group> together with a feed callback.	2004	use an C<aio_group> together with a feed callback.
1581		2005
1582	It's main use is in scripts without an event loop - when you want to stat	2006	Its main use is in scripts without an event loop - when you want to stat
1583	a lot of files, you can write somehting like this:	2007	a lot of files, you can write somehting like this:
1584		2008
1585	IO::AIO::max_outstanding 32;	2009	IO::AIO::max_outstanding 32;
1586		2010
1587	for my $path (...) {	2011	for my $path (...) {
…		…
1627		2051
1628	=back	2052	=back
1629		2053
1630	=head3 MISCELLANEOUS FUNCTIONS	2054	=head3 MISCELLANEOUS FUNCTIONS
1631		2055
1632	IO::AIO implements some functions that might be useful, but are not	2056	IO::AIO implements some functions that are useful when you want to use
1633	asynchronous.	2057	some "Advanced I/O" function not available to in Perl, without going the
		2058	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2059	counterpart.
1634		2060
1635	=over 4	2061	=over 4
1636		2062
1637	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2063	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1638		2064
…		…
1645		2071
1646	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2072	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1647		2073
1648	Simply calls the C<posix_fadvise> function (see its	2074	Simply calls the C<posix_fadvise> function (see its
1649	manpage for details). The following advice constants are	2075	manpage for details). The following advice constants are
1650	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2076	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1651	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2077	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1652	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2078	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1653		2079
1654	On systems that do not implement C<posix_fadvise>, this function returns	2080	On systems that do not implement C<posix_fadvise>, this function returns
1655	ENOSYS, otherwise the return value of C<posix_fadvise>.	2081	ENOSYS, otherwise the return value of C<posix_fadvise>.
1656		2082
1657	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2083	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1658		2084
1659	Simply calls the C<posix_madvise> function (see its	2085	Simply calls the C<posix_madvise> function (see its
1660	manpage for details). The following advice constants are	2086	manpage for details). The following advice constants are
1661	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2087	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1662	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2088	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
		2089	C<IO::AIO::MADV_FREE>.
		2090
		2091	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2092	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2093	will be reduced to fit into the C<$scalar>.
1663		2094
1664	On systems that do not implement C<posix_madvise>, this function returns	2095	On systems that do not implement C<posix_madvise>, this function returns
1665	ENOSYS, otherwise the return value of C<posix_madvise>.	2096	ENOSYS, otherwise the return value of C<posix_madvise>.
1666		2097
1667	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2098	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1668		2099
1669	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2100	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1670	$scalar (see its manpage for details). The following protect	2101	$scalar (see its manpage for details). The following protect
1671	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2102	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1672	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2103	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2104
		2105	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2106	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2107	will be reduced to fit into the C<$scalar>.
1673		2108
1674	On systems that do not implement C<mprotect>, this function returns	2109	On systems that do not implement C<mprotect>, this function returns
1675	ENOSYS, otherwise the return value of C<mprotect>.	2110	ENOSYS, otherwise the return value of C<mprotect>.
1676		2111
1677	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2112	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1678		2113
1679	Memory-maps a file (or anonymous memory range) and attaches it to the	2114	Memory-maps a file (or anonymous memory range) and attaches it to the
1680	given C<$scalar>, which will act like a string scalar.	2115	given C<$scalar>, which will act like a string scalar. Returns true on
		2116	success, and false otherwise.
1681		2117
		2118	The scalar must exist, but its contents do not matter - this means you
		2119	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2120	the scalar first.
		2121
1682	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2122	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1683	change the string length, and most read-only operations such as copying it	2123	which don't change the string length, and most read-only operations such
1684	or searching it with regexes and so on.	2124	as copying it or searching it with regexes and so on.
1685		2125
1686	Anything else is unsafe and will, at best, result in memory leaks.	2126	Anything else is unsafe and will, at best, result in memory leaks.
1687		2127
1688	The memory map associated with the C<$scalar> is automatically removed	2128	The memory map associated with the C<$scalar> is automatically removed
1689	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2129	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1690	C<IO::AIO::munmap> functions are called.	2130	or C<IO::AIO::munmap> functions are called on it.
1691		2131
1692	This calls the C<mmap>(2) function internally. See your system's manual	2132	This calls the C<mmap>(2) function internally. See your system's manual
1693	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2133	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1694		2134
1695	The C<$length> must be larger than zero and smaller than the actual	2135	The C<$length> must be larger than zero and smaller than the actual
1696	filesize.	2136	filesize.
1697		2137
1698	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2138	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1699	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2139	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1700		2140
1701	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2141	C<$flags> can be a combination of
1702	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2142	C<IO::AIO::MAP_SHARED> or
1703	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2143	C<IO::AIO::MAP_PRIVATE>,
		2144	or a number of system-specific flags (when not available, the are C<0>):
1704	(which is set to C<MAP_ANON> if your system only provides this	2145	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1705	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2146	C<IO::AIO::MAP_LOCKED>,
1706	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2147	C<IO::AIO::MAP_NORESERVE>,
		2148	C<IO::AIO::MAP_POPULATE>,
1707	C<IO::AIO::MAP_NONBLOCK>	2149	C<IO::AIO::MAP_NONBLOCK>,
		2150	C<IO::AIO::MAP_FIXED>,
		2151	C<IO::AIO::MAP_GROWSDOWN>,
		2152	C<IO::AIO::MAP_32BIT>,
		2153	C<IO::AIO::MAP_HUGETLB> or
		2154	C<IO::AIO::MAP_STACK>.
1708		2155
1709	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2156	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1710		2157
1711	C<$offset> is the offset from the start of the file - it generally must be	2158	C<$offset> is the offset from the start of the file - it generally must be
1712	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2159	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1737		2184
1738	Calls the C<munlockall> function.	2185	Calls the C<munlockall> function.
1739		2186
1740	On systems that do not implement C<munlockall>, this function returns	2187	On systems that do not implement C<munlockall>, this function returns
1741	ENOSYS, otherwise the return value of C<munlockall>.	2188	ENOSYS, otherwise the return value of C<munlockall>.
		2189
		2190	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2191
		2192	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2193	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2194	should be the file offset.
		2195
		2196	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2197	silently corrupt the data in this case.
		2198
		2199	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2200	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2201	C<IO::AIO::SPLICE_F_GIFT>.
		2202
		2203	See the C<splice(2)> manpage for details.
		2204
		2205	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2206
		2207	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2208	description for C<IO::AIO::splice> above for details.
		2209
		2210	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2211
		2212	Attempts to query or change the pipe buffer size. Obviously works only
		2213	on pipes, and currently works only on GNU/Linux systems, and fails with
		2214	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2215	size on other systems, drop me a note.
		2216
		2217	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2218
		2219	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2220	C<$flags> is missing or C<0>, then this should be the same as a call to
		2221	perl's built-in C<pipe> function and create a new pipe, and works on
		2222	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2223	(..., 4096, O_BINARY)>.
		2224
		2225	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2226	the given flags (Linux 2.6.27, glibc 2.9).
		2227
		2228	On success, the read and write file handles are returned.
		2229
		2230	On error, nothing will be returned. If the pipe2 syscall is missing and
		2231	C<$flags> is non-zero, fails with C<ENOSYS>.
		2232
		2233	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2234	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2235	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1742		2236
1743	=back	2237	=back
1744		2238
1745	=cut	2239	=cut
1746		2240
…		…
1781	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2275	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1782	\&IO::AIO::poll_cb);	2276	\&IO::AIO::poll_cb);
1783		2277
1784	=head2 FORK BEHAVIOUR	2278	=head2 FORK BEHAVIOUR
1785		2279
1786	This module should do "the right thing" when the process using it forks:	2280	Usage of pthreads in a program changes the semantics of fork
		2281	considerably. Specifically, only async-safe functions can be called after
		2282	fork. Perl doesn't know about this, so in general, you cannot call fork
		2283	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2284	pthreads, so this applies, but many other extensions and (for inexplicable
		2285	reasons) perl itself often is linked against pthreads, so this limitation
		2286	applies to quite a lot of perls.
1787		2287
1788	Before the fork, IO::AIO enters a quiescent state where no requests	2288	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1789	can be added in other threads and no results will be processed. After	2289	only works in the process that loaded it. Forking is fully supported, but
1790	the fork the parent simply leaves the quiescent state and continues	2290	using IO::AIO in the child is not.
1791	request/result processing, while the child frees the request/result queue
1792	(so that the requests started before the fork will only be handled in the
1793	parent). Threads will be started on demand until the limit set in the
1794	parent process has been reached again.
1795		2291
1796	In short: the parent will, after a short pause, continue as if fork had	2292	You might get around by not I<using> IO::AIO before (or after)
1797	not been called, while the child will act as if IO::AIO has not been used	2293	forking. You could also try to call the L<IO::AIO::reinit> function in the
1798	yet.	2294	child:
		2295
		2296	=over 4
		2297
		2298	=item IO::AIO::reinit
		2299
		2300	Abandons all current requests and I/O threads and simply reinitialises all
		2301	data structures. This is not an operation supported by any standards, but
		2302	happens to work on GNU/Linux and some newer BSD systems.
		2303
		2304	The only reasonable use for this function is to call it after forking, if
		2305	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2306	the process will result in undefined behaviour. Calling it at any time
		2307	will also result in any undefined (by POSIX) behaviour.
		2308
		2309	=back
1799		2310
1800	=head2 MEMORY USAGE	2311	=head2 MEMORY USAGE
1801		2312
1802	Per-request usage:	2313	Per-request usage:
1803		2314

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing IO-AIO/AIO.pm (file contents): Revision 1.195 by root, Fri May 27 19:56:31 2011 UTC vs. Revision 1.270 by root, Fri Jun 23 03:23:19 2017 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.195 by root, Fri May 27 19:56:31 2011 UTC vs.
Revision 1.270 by root, Fri Jun 23 03:23:19 2017 UTC