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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.193 by root, Thu May 26 04:15:37 2011 UTC vs.
Revision 1.268 by root, Tue May 30 22:45:52 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 = '3.8';	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_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)
228	aio_mkdir $pathname, $mode, $callback->($status)	238	aio_mkdir $pathname, $mode, $callback->($status)
229	aio_rmdir $pathname, $callback->($status)	239	aio_rmdir $pathname, $callback->($status)
230	aio_readdir $pathname, $callback->($entries)	240	aio_readdir $pathname, $callback->($entries)
231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	241	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	242	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	243	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		244	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
234	aio_load $path, $data, $callback->($status)	245	aio_load $pathname, $data, $callback->($status)
235	aio_copy $srcpath, $dstpath, $callback->($status)	246	aio_copy $srcpath, $dstpath, $callback->($status)
236	aio_move $srcpath, $dstpath, $callback->($status)	247	aio_move $srcpath, $dstpath, $callback->($status)
237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238	aio_rmtree $path, $callback->($status)	248	aio_rmtree $pathname, $callback->($status)
		249	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		250	aio_ioctl $fh, $request, $buf, $callback->($status)
239	aio_sync $callback->($status)	251	aio_sync $callback->($status)
		252	aio_syncfs $fh, $callback->($status)
240	aio_fsync $fh, $callback->($status)	253	aio_fsync $fh, $callback->($status)
241	aio_fdatasync $fh, $callback->($status)	254	aio_fdatasync $fh, $callback->($status)
242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	255	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243	aio_pathsync $path, $callback->($status)	256	aio_pathsync $pathname, $callback->($status)
244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	257	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	258	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	259	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247	aio_mlockall $flags, $callback->($status)	260	aio_mlockall $flags, $callback->($status)
248	aio_group $callback->(...)	261	aio_group $callback->(...)
249	aio_nop $callback->()	262	aio_nop $callback->()
…		…
266	IO::AIO::nready	279	IO::AIO::nready
267	IO::AIO::npending	280	IO::AIO::npending
268		281
269	IO::AIO::sendfile $ofh, $ifh, $offset, $count	282	IO::AIO::sendfile $ofh, $ifh, $offset, $count
270	IO::AIO::fadvise $fh, $offset, $len, $advice	283	IO::AIO::fadvise $fh, $offset, $len, $advice
		284	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		285	IO::AIO::munmap $scalar
271	IO::AIO::madvise $scalar, $offset, $length, $advice	286	IO::AIO::madvise $scalar, $offset, $length, $advice
272	IO::AIO::mprotect $scalar, $offset, $length, $protect	287	IO::AIO::mprotect $scalar, $offset, $length, $protect
273	IO::AIO::munlock $scalar, $offset = 0, $length = undef	288	IO::AIO::munlock $scalar, $offset = 0, $length = undef
274	IO::AIO::munlockall	289	IO::AIO::munlockall
275		290
276	=head2 AIO REQUEST FUNCTIONS	291	=head2 API NOTES
277		292
278	All the C<aio_*> calls are more or less thin wrappers around the syscall	293	All the C<aio_*> calls are more or less thin wrappers around the syscall
279	with the same name (sans C<aio_>). The arguments are similar or identical,	294	with the same name (sans C<aio_>). The arguments are similar or identical,
280	and they all accept an additional (and optional) C<$callback> argument	295	and they all accept an additional (and optional) C<$callback> argument
281	which must be a code reference. This code reference will get called with	296	which must be a code reference. This code reference will be called after
282	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	297	the syscall has been executed in an asynchronous fashion. The results
283	perl, which usually delivers "false") as its sole argument after the given	298	of the request will be passed as arguments to the callback (and, if an
284	syscall has been executed asynchronously.	299	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		300	most syscalls return C<-1> on error, unlike perl, which usually delivers
		301	"false").
		302
		303	Some requests (such as C<aio_readdir>) pass the actual results and
		304	communicate failures by passing C<undef>.
285		305
286	All functions expecting a filehandle keep a copy of the filehandle	306	All functions expecting a filehandle keep a copy of the filehandle
287	internally until the request has finished.	307	internally until the request has finished.
288		308
289	All functions return request objects of type L<IO::AIO::REQ> that allow	309	All functions return request objects of type L<IO::AIO::REQ> that allow
290	further manipulation of those requests while they are in-flight.	310	further manipulation of those requests while they are in-flight.
291		311
292	The pathnames you pass to these routines I<must> be absolute and	312	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	313	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	314	current working directory could have changed. Alternatively, you can
295	changed. Alternatively, you can make sure that you never change the	315	make sure that you never change the current working directory anywhere
296	current working directory anywhere in the program and then use relative	316	in the program and then use relative paths. You can also take advantage
297	paths.	317	of IO::AIOs working directory abstraction, that lets you specify paths
		318	relative to some previously-opened "working directory object" - see the
		319	description of the C<IO::AIO::WD> class later in this document.
298		320
299	To encode pathnames as octets, either make sure you either: a) always pass	321	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	322	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	323	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	324	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)	325	effect in the user environment, d) use Glib::filename_from_unicode on
304	use something else to ensure your scalar has the correct contents.	326	unicode filenames or e) use something else to ensure your scalar has the
		327	correct contents.
305		328
306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	329	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
307	handles correctly whether it is set or not.	330	handles correctly whether it is set or not.
		331
		332	=head2 AIO REQUEST FUNCTIONS
308		333
309	=over 4	334	=over 4
310		335
311	=item $prev_pri = aioreq_pri [$pri]	336	=item $prev_pri = aioreq_pri [$pri]
312		337
…		…
342		367
343		368
344	=item aio_open $pathname, $flags, $mode, $callback->($fh)	369	=item aio_open $pathname, $flags, $mode, $callback->($fh)
345		370
346	Asynchronously open or create a file and call the callback with a newly	371	Asynchronously open or create a file and call the callback with a newly
347	created filehandle for the file.	372	created filehandle for the file (or C<undef> in case of an error).
348		373
349	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	374	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
350	for an explanation.	375	for an explanation.
351		376
352	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	377	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
368	} else {	393	} else {
369	die "open failed: $!\n";	394	die "open failed: $!\n";
370	}	395	}
371	};	396	};
372		397
		398	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		399	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		400	following POSIX and non-POSIX constants are available (missing ones on
		401	your system are, as usual, C<0>):
		402
		403	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		404	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		405	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		406
373		407
374	=item aio_close $fh, $callback->($status)	408	=item aio_close $fh, $callback->($status)
375		409
376	Asynchronously close a file and call the callback with the result	410	Asynchronously close a file and call the callback with the result
377	code.	411	code.
…		…
386	Or in other words: the file descriptor will be closed, but it will not be	420	Or in other words: the file descriptor will be closed, but it will not be
387	free for reuse until the perl filehandle is closed.	421	free for reuse until the perl filehandle is closed.
388		422
389	=cut	423	=cut
390		424
		425	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		426
		427	Seeks the filehandle to the new C<$offset>, similarly to perl's
		428	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		429	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		430	C<IO::AIO::SEEK_END>).
		431
		432	The resulting absolute offset will be passed to the callback, or C<-1> in
		433	case of an error.
		434
		435	In theory, the C<$whence> constants could be different than the
		436	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		437	so don't panic.
		438
		439	As a GNU/Linux (and maybe Solaris) extension, also the constants
		440	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		441	could be found. No guarantees about suitability for use in C<aio_seek> or
		442	Perl's C<sysseek> can be made though, although I would naively assume they
		443	"just work".
		444
391	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	445	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
392		446
393	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	447	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
394		448
395	Reads or writes C<$length> bytes from or to the specified C<$fh> and	449	Reads or writes C<$length> bytes from or to the specified C<$fh> and
396	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	450	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
397	and calls the callback without the actual number of bytes read (or -1 on	451	calls the callback with the actual number of bytes transferred (or -1 on
398	error, just like the syscall).	452	error, just like the syscall).
399		453
400	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	454	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
401	offset plus the actual number of bytes read.	455	offset plus the actual number of bytes read.
402		456
…		…
427		481
428	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	482	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
429	reading at byte offset C<$in_offset>, and starts writing at the current	483	reading at byte offset C<$in_offset>, and starts writing at the current
430	file offset of C<$out_fh>. Because of that, it is not safe to issue more	484	file offset of C<$out_fh>. Because of that, it is not safe to issue more
431	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	485	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
432	other.	486	other. The same C<$in_fh> works fine though, as this function does not
		487	move or use the file offset of C<$in_fh>.
433		488
434	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than	489	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
435	are written, and there is no way to find out how many bytes have been read	490	are written, and there is no way to find out how many more bytes have been
436	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of	491	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
437	bytes written to C<$out_fh>. Only if the result value equals C<$length>	492	number of bytes written to C<$out_fh>. Only if the result value equals
438	one can assume that C<$length> bytes have been read.	493	C<$length> one can assume that C<$length> bytes have been read.
439		494
440	Unlike with other C<aio_> functions, it makes a lot of sense to use	495	Unlike with other C<aio_> functions, it makes a lot of sense to use
441	C<aio_sendfile> on non-blocking sockets, as long as one end (typically	496	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
442	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while	497	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
443	the socket I/O will be non-blocking. Note, however, that you can run into	498	the socket I/O will be non-blocking. Note, however, that you can run
444	a trap where C<aio_sendfile> reads some data with readahead, then fails	499	into a trap where C<aio_sendfile> reads some data with readahead, then
445	to write all data, and when the socket is ready the next time, the data	500	fails to write all data, and when the socket is ready the next time, the
446	in the cache is already lost, forcing C<aio_sendfile> to again hit the	501	data in the cache is already lost, forcing C<aio_sendfile> to again hit
447	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage	502	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
448	much better.	503	resource usage.
449		504
450	This call tries to make use of a native C<sendfile> syscall to provide	505	This call tries to make use of a native C<sendfile>-like syscall to
451	zero-copy operation. For this to work, C<$out_fh> should refer to a	506	provide zero-copy operation. For this to work, C<$out_fh> should refer to
452	socket, and C<$in_fh> should refer to an mmap'able file.	507	a socket, and C<$in_fh> should refer to an mmap'able file.
453		508
454	If a native sendfile cannot be found or it fails with C<ENOSYS>,	509	If a native sendfile cannot be found or it fails with C<ENOSYS>,
455	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	510	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
456	it will be emulated, so you can call C<aio_sendfile> on any type of	511	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
457	filehandle regardless of the limitations of the operating system.	512	type of filehandle regardless of the limitations of the operating system.
		513
		514	As native sendfile syscalls (as practically any non-POSIX interface hacked
		515	together in a hurry to improve benchmark numbers) tend to be rather buggy
		516	on many systems, this implementation tries to work around some known bugs
		517	in Linux and FreeBSD kernels (probably others, too), but that might fail,
		518	so you really really should check the return value of C<aio_sendfile> -
		519	fewer bytes than expected might have been transferred.
458		520
459		521
460	=item aio_readahead $fh,$offset,$length, $callback->($retval)	522	=item aio_readahead $fh,$offset,$length, $callback->($retval)
461		523
462	C<aio_readahead> populates the page cache with data from a file so that	524	C<aio_readahead> populates the page cache with data from a file so that
…		…
466	whole pages, so that offset is effectively rounded down to a page boundary	528	whole pages, so that offset is effectively rounded down to a page boundary
467	and bytes are read up to the next page boundary greater than or equal to	529	and bytes are read up to the next page boundary greater than or equal to
468	(off-set+length). C<aio_readahead> does not read beyond the end of the	530	(off-set+length). C<aio_readahead> does not read beyond the end of the
469	file. The current file offset of the file is left unchanged.	531	file. The current file offset of the file is left unchanged.
470		532
471	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	533	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
472	emulated by simply reading the data, which would have a similar effect.	534	be emulated by simply reading the data, which would have a similar effect.
473		535
474		536
475	=item aio_stat $fh_or_path, $callback->($status)	537	=item aio_stat $fh_or_path, $callback->($status)
476		538
477	=item aio_lstat $fh, $callback->($status)	539	=item aio_lstat $fh, $callback->($status)
…		…
546	namemax => 255,	608	namemax => 255,
547	frsize => 1024,	609	frsize => 1024,
548	fsid => 1810	610	fsid => 1810
549	}	611	}
550		612
		613	Here is a (likely partial - send me updates!) list of fsid values used by
		614	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		615
		616	0x0000adf5 adfs
		617	0x0000adff affs
		618	0x5346414f afs
		619	0x09041934 anon-inode filesystem
		620	0x00000187 autofs
		621	0x42465331 befs
		622	0x1badface bfs
		623	0x42494e4d binfmt_misc
		624	0x9123683e btrfs
		625	0x0027e0eb cgroupfs
		626	0xff534d42 cifs
		627	0x73757245 coda
		628	0x012ff7b7 coh
		629	0x28cd3d45 cramfs
		630	0x453dcd28 cramfs-wend (wrong endianness)
		631	0x64626720 debugfs
		632	0x00001373 devfs
		633	0x00001cd1 devpts
		634	0x0000f15f ecryptfs
		635	0x00414a53 efs
		636	0x0000137d ext
		637	0x0000ef53 ext2/ext3/ext4
		638	0x0000ef51 ext2
		639	0xf2f52010 f2fs
		640	0x00004006 fat
		641	0x65735546 fuseblk
		642	0x65735543 fusectl
		643	0x0bad1dea futexfs
		644	0x01161970 gfs2
		645	0x47504653 gpfs
		646	0x00004244 hfs
		647	0xf995e849 hpfs
		648	0x00c0ffee hostfs
		649	0x958458f6 hugetlbfs
		650	0x2bad1dea inotifyfs
		651	0x00009660 isofs
		652	0x000072b6 jffs2
		653	0x3153464a jfs
		654	0x6b414653 k-afs
		655	0x0bd00bd0 lustre
		656	0x0000137f minix
		657	0x0000138f minix 30 char names
		658	0x00002468 minix v2
		659	0x00002478 minix v2 30 char names
		660	0x00004d5a minix v3
		661	0x19800202 mqueue
		662	0x00004d44 msdos
		663	0x0000564c novell
		664	0x00006969 nfs
		665	0x6e667364 nfsd
		666	0x00003434 nilfs
		667	0x5346544e ntfs
		668	0x00009fa1 openprom
		669	0x7461636F ocfs2
		670	0x00009fa0 proc
		671	0x6165676c pstorefs
		672	0x0000002f qnx4
		673	0x68191122 qnx6
		674	0x858458f6 ramfs
		675	0x52654973 reiserfs
		676	0x00007275 romfs
		677	0x67596969 rpc_pipefs
		678	0x73636673 securityfs
		679	0xf97cff8c selinux
		680	0x0000517b smb
		681	0x534f434b sockfs
		682	0x73717368 squashfs
		683	0x62656572 sysfs
		684	0x012ff7b6 sysv2
		685	0x012ff7b5 sysv4
		686	0x01021994 tmpfs
		687	0x15013346 udf
		688	0x00011954 ufs
		689	0x54190100 ufs byteswapped
		690	0x00009fa2 usbdevfs
		691	0x01021997 v9fs
		692	0xa501fcf5 vxfs
		693	0xabba1974 xenfs
		694	0x012ff7b4 xenix
		695	0x58465342 xfs
		696	0x012fd16d xia
551		697
552	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	698	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
553		699
554	Works like perl's C<utime> function (including the special case of $atime	700	Works like perl's C<utime> function (including the special case of $atime
555	and $mtime being undef). Fractional times are supported if the underlying	701	and $mtime being undef). Fractional times are supported if the underlying
…		…
583	=item aio_truncate $fh_or_path, $offset, $callback->($status)	729	=item aio_truncate $fh_or_path, $offset, $callback->($status)
584		730
585	Works like truncate(2) or ftruncate(2).	731	Works like truncate(2) or ftruncate(2).
586		732
587		733
		734	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		735
		736	Allocates or frees disk space according to the C<$mode> argument. See the
		737	linux C<fallocate> documentation for details.
		738
		739	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		740	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE \| IO::AIO::FALLOC_FL_KEEP_SIZE>,
		741	to deallocate a file range.
		742
		743	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		744	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		745	your L<fallocate(2)> manpage).
		746
		747	The file system block size used by C<fallocate> is presumably the
		748	C<f_bsize> returned by C<statvfs>.
		749
		750	If C<fallocate> isn't available or cannot be emulated (currently no
		751	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		752
		753
588	=item aio_chmod $fh_or_path, $mode, $callback->($status)	754	=item aio_chmod $fh_or_path, $mode, $callback->($status)
589		755
590	Works like perl's C<chmod> function.	756	Works like perl's C<chmod> function.
591		757
592		758
…		…
594		760
595	Asynchronously unlink (delete) a file and call the callback with the	761	Asynchronously unlink (delete) a file and call the callback with the
596	result code.	762	result code.
597		763
598		764
599	=item aio_mknod $path, $mode, $dev, $callback->($status)	765	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
600		766
601	[EXPERIMENTAL]	767	[EXPERIMENTAL]
602		768
603	Asynchronously create a device node (or fifo). See mknod(2).	769	Asynchronously create a device node (or fifo). See mknod(2).
604		770
605	The only (POSIX-) portable way of calling this function is:	771	The only (POSIX-) portable way of calling this function is:
606		772
607	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	773	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
608		774
609	See C<aio_stat> for info about some potentially helpful extra constants	775	See C<aio_stat> for info about some potentially helpful extra constants
610	and functions.	776	and functions.
611		777
612	=item aio_link $srcpath, $dstpath, $callback->($status)	778	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
619		785
620	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	786	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
621	the path C<$dstpath> and call the callback with the result code.	787	the path C<$dstpath> and call the callback with the result code.
622		788
623		789
624	=item aio_readlink $path, $callback->($link)	790	=item aio_readlink $pathname, $callback->($link)
625		791
626	Asynchronously read the symlink specified by C<$path> and pass it to	792	Asynchronously read the symlink specified by C<$path> and pass it to
627	the callback. If an error occurs, nothing or undef gets passed to the	793	the callback. If an error occurs, nothing or undef gets passed to the
628	callback.	794	callback.
629		795
630		796
		797	=item aio_realpath $pathname, $callback->($path)
		798
		799	Asynchronously make the path absolute and resolve any symlinks in
		800	C<$path>. The resulting path only consists of directories (same as
		801	L<Cwd::realpath>).
		802
		803	This request can be used to get the absolute path of the current working
		804	directory by passing it a path of F<.> (a single dot).
		805
		806
631	=item aio_rename $srcpath, $dstpath, $callback->($status)	807	=item aio_rename $srcpath, $dstpath, $callback->($status)
632		808
633	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	809	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
634	rename(2) and call the callback with the result code.	810	rename(2) and call the callback with the result code.
		811
		812	On systems that support the AIO::WD working directory abstraction
		813	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		814	of failing, C<rename> is called on the absolute path of C<$wd>.
635		815
636		816
637	=item aio_mkdir $pathname, $mode, $callback->($status)	817	=item aio_mkdir $pathname, $mode, $callback->($status)
638		818
639	Asynchronously mkdir (create) a directory and call the callback with	819	Asynchronously mkdir (create) a directory and call the callback with
…		…
644	=item aio_rmdir $pathname, $callback->($status)	824	=item aio_rmdir $pathname, $callback->($status)
645		825
646	Asynchronously rmdir (delete) a directory and call the callback with the	826	Asynchronously rmdir (delete) a directory and call the callback with the
647	result code.	827	result code.
648		828
		829	On systems that support the AIO::WD working directory abstraction
		830	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		831	C<rmdir> is called on the absolute path of C<$wd>.
		832
649		833
650	=item aio_readdir $pathname, $callback->($entries)	834	=item aio_readdir $pathname, $callback->($entries)
651		835
652	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	836	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
653	directory (i.e. opendir + readdir + closedir). The entries will not be	837	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
657	array-ref with the filenames.	841	array-ref with the filenames.
658		842
659		843
660	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	844	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
661		845
662	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	846	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
663	behaviour and output format. In case of an error, C<$entries> will be	847	tune behaviour and output format. In case of an error, C<$entries> will be
664	C<undef>.	848	C<undef>.
665		849
666	The flags are a combination of the following constants, ORed together (the	850	The flags are a combination of the following constants, ORed together (the
667	flags will also be passed to the callback, possibly modified):	851	flags will also be passed to the callback, possibly modified):
668		852
…		…
715		899
716	=item IO::AIO::READDIR_FOUND_UNKNOWN	900	=item IO::AIO::READDIR_FOUND_UNKNOWN
717		901
718	This flag should not be set when calling C<aio_readdirx>. Instead, it	902	This flag should not be set when calling C<aio_readdirx>. Instead, it
719	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	903	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
720	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	904	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
721	C<$type>'s are known, which can be used to speed up some algorithms.	905	C<$type>'s are known, which can be used to speed up some algorithms.
722		906
723	=back	907	=back
724		908
725		909
726	=item aio_load $path, $data, $callback->($status)	910	=item aio_load $pathname, $data, $callback->($status)
727		911
728	This is a composite request that tries to fully load the given file into	912	This is a composite request that tries to fully load the given file into
729	memory. Status is the same as with aio_read.	913	memory. Status is the same as with aio_read.
730		914
731	=cut	915	=cut
…		…
853	if ($_[0] && $! == EXDEV) {	1037	if ($_[0] && $! == EXDEV) {
854	aioreq_pri $pri;	1038	aioreq_pri $pri;
855	add $grp aio_copy $src, $dst, sub {	1039	add $grp aio_copy $src, $dst, sub {
856	$grp->result ($_[0]);	1040	$grp->result ($_[0]);
857		1041
858	if (!$_[0]) {	1042	unless ($_[0]) {
859	aioreq_pri $pri;	1043	aioreq_pri $pri;
860	add $grp aio_unlink $src;	1044	add $grp aio_unlink $src;
861	}	1045	}
862	};	1046	};
863	} else {	1047	} else {
…		…
866	};	1050	};
867		1051
868	$grp	1052	$grp
869	}	1053	}
870		1054
871	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1055	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
872		1056
873	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1057	Scans a directory (similar to C<aio_readdir>) but additionally tries to
874	efficiently separate the entries of directory C<$path> into two sets of	1058	efficiently separate the entries of directory C<$path> into two sets of
875	names, directories you can recurse into (directories), and ones you cannot	1059	names, directories you can recurse into (directories), and ones you cannot
876	recurse into (everything else, including symlinks to directories).	1060	recurse into (everything else, including symlinks to directories).
…		…
907	Then entries will be sorted into likely directories a non-initial dot	1091	Then entries will be sorted into likely directories a non-initial dot
908	currently) and likely non-directories (see C<aio_readdirx>). Then every	1092	currently) and likely non-directories (see C<aio_readdirx>). Then every
909	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1093	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
910	in order of their inode numbers. If that succeeds, it assumes that the	1094	in order of their inode numbers. If that succeeds, it assumes that the
911	entry is a directory or a symlink to directory (which will be checked	1095	entry is a directory or a symlink to directory (which will be checked
912	seperately). This is often faster than stat'ing the entry itself because	1096	separately). This is often faster than stat'ing the entry itself because
913	filesystems might detect the type of the entry without reading the inode	1097	filesystems might detect the type of the entry without reading the inode
914	data (e.g. ext2fs filetype feature), even on systems that cannot return	1098	data (e.g. ext2fs filetype feature), even on systems that cannot return
915	the filetype information on readdir.	1099	the filetype information on readdir.
916		1100
917	If the known number of directories (link count - 2) has been reached, the	1101	If the known number of directories (link count - 2) has been reached, the
…		…
933		1117
934	my $grp = aio_group $cb;	1118	my $grp = aio_group $cb;
935		1119
936	$maxreq = 4 if $maxreq <= 0;	1120	$maxreq = 4 if $maxreq <= 0;
937		1121
938	# stat once	1122	# get a wd object
939	aioreq_pri $pri;	1123	aioreq_pri $pri;
940	add $grp aio_stat $path, sub {	1124	add $grp aio_wd $path, sub {
		1125	$_[0]
941	return $grp->result () if $_[0];	1126	or return $grp->result ();
942	my $now = time;
943	my $hash1 = join ":", (stat _)[0,1,3,7,9];
944		1127
945	# read the directory entries	1128	my $wd = [shift, "."];
		1129
		1130	# stat once
946	aioreq_pri $pri;	1131	aioreq_pri $pri;
947	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1132	add $grp aio_stat $wd, sub {
948	my $entries = shift
949	or return $grp->result ();	1133	return $grp->result () if $_[0];
		1134	my $now = time;
		1135	my $hash1 = join ":", (stat _)[0,1,3,7,9];
950		1136
951	# stat the dir another time	1137	# read the directory entries
952	aioreq_pri $pri;	1138	aioreq_pri $pri;
		1139	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1140	my $entries = shift
		1141	or return $grp->result ();
		1142
		1143	# stat the dir another time
		1144	aioreq_pri $pri;
953	add $grp aio_stat $path, sub {	1145	add $grp aio_stat $wd, sub {
954	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1146	my $hash2 = join ":", (stat _)[0,1,3,7,9];
955		1147
956	my $ndirs;	1148	my $ndirs;
957		1149
958	# take the slow route if anything looks fishy	1150	# take the slow route if anything looks fishy
959	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1151	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
960	$ndirs = -1;	1152	$ndirs = -1;
961	} else {	1153	} else {
962	# if nlink == 2, we are finished	1154	# if nlink == 2, we are finished
963	# for non-posix-fs's, we rely on nlink < 2	1155	# for non-posix-fs's, we rely on nlink < 2
964	$ndirs = (stat _)[3] - 2	1156	$ndirs = (stat _)[3] - 2
965	or return $grp->result ([], $entries);	1157	or return $grp->result ([], $entries);
966	}	1158	}
967		1159
968	my (@dirs, @nondirs);	1160	my (@dirs, @nondirs);
969		1161
970	my $statgrp = add $grp aio_group sub {	1162	my $statgrp = add $grp aio_group sub {
971	$grp->result (\@dirs, \@nondirs);	1163	$grp->result (\@dirs, \@nondirs);
972	};	1164	};
973		1165
974	limit $statgrp $maxreq;	1166	limit $statgrp $maxreq;
975	feed $statgrp sub {	1167	feed $statgrp sub {
976	return unless @$entries;	1168	return unless @$entries;
977	my $entry = shift @$entries;	1169	my $entry = shift @$entries;
978		1170
979	aioreq_pri $pri;	1171	aioreq_pri $pri;
		1172	$wd->[1] = "$entry/.";
980	add $statgrp aio_stat "$path/$entry/.", sub {	1173	add $statgrp aio_stat $wd, sub {
981	if ($_[0] < 0) {	1174	if ($_[0] < 0) {
982	push @nondirs, $entry;	1175	push @nondirs, $entry;
983	} else {	1176	} else {
984	# need to check for real directory	1177	# need to check for real directory
985	aioreq_pri $pri;	1178	aioreq_pri $pri;
		1179	$wd->[1] = $entry;
986	add $statgrp aio_lstat "$path/$entry", sub {	1180	add $statgrp aio_lstat $wd, sub {
987	if (-d _) {	1181	if (-d _) {
988	push @dirs, $entry;	1182	push @dirs, $entry;
989		1183
990	unless (--$ndirs) {	1184	unless (--$ndirs) {
991	push @nondirs, @$entries;	1185	push @nondirs, @$entries;
992	feed $statgrp;	1186	feed $statgrp;
		1187	}
		1188	} else {
		1189	push @nondirs, $entry;
993	}	1190	}
994	} else {
995	push @nondirs, $entry;
996	}	1191	}
997	}	1192	}
998	}	1193	};
999	};	1194	};
1000	};	1195	};
1001	};	1196	};
1002	};	1197	};
1003	};	1198	};
1004		1199
1005	$grp	1200	$grp
1006	}	1201	}
1007		1202
1008	=item aio_rmtree $path, $callback->($status)	1203	=item aio_rmtree $pathname, $callback->($status)
1009		1204
1010	Delete a directory tree starting (and including) C<$path>, return the	1205	Delete a directory tree starting (and including) C<$path>, return the
1011	status of the final C<rmdir> only. This is a composite request that	1206	status of the final C<rmdir> only. This is a composite request that
1012	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1207	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1013	everything else.	1208	everything else.
1014		1209
1015	=cut	1210	=cut
1016		1211
…		…
1038	};	1233	};
1039		1234
1040	$grp	1235	$grp
1041	}	1236	}
1042		1237
		1238	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1239
		1240	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1241
		1242	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1243	they execute asynchronously and pass the return value to the callback.
		1244
		1245	Both calls can be used for a lot of things, some of which make more sense
		1246	to run asynchronously in their own thread, while some others make less
		1247	sense. For example, calls that block waiting for external events, such
		1248	as locking, will also lock down an I/O thread while it is waiting, which
		1249	can deadlock the whole I/O system. At the same time, there might be no
		1250	alternative to using a thread to wait.
		1251
		1252	So in general, you should only use these calls for things that do
		1253	(filesystem) I/O, not for things that wait for other events (network,
		1254	other processes), although if you are careful and know what you are doing,
		1255	you still can.
		1256
		1257	The following constants are available (missing ones are, as usual C<0>):
		1258
		1259	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1260
		1261	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1262	C<FS_IOC_FIEMAP>.
		1263
		1264	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1265	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1266
		1267	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1268	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1269	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1270	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1271	C<FS_FL_USER_MODIFIABLE>.
		1272
		1273	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1274	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1275	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1276	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1277
1043	=item aio_sync $callback->($status)	1278	=item aio_sync $callback->($status)
1044		1279
1045	Asynchronously call sync and call the callback when finished.	1280	Asynchronously call sync and call the callback when finished.
1046		1281
1047	=item aio_fsync $fh, $callback->($status)	1282	=item aio_fsync $fh, $callback->($status)
…		…
1054	Asynchronously call fdatasync on the given filehandle and call the	1289	Asynchronously call fdatasync on the given filehandle and call the
1055	callback with the fdatasync result code.	1290	callback with the fdatasync result code.
1056		1291
1057	If this call isn't available because your OS lacks it or it couldn't be	1292	If this call isn't available because your OS lacks it or it couldn't be
1058	detected, it will be emulated by calling C<fsync> instead.	1293	detected, it will be emulated by calling C<fsync> instead.
		1294
		1295	=item aio_syncfs $fh, $callback->($status)
		1296
		1297	Asynchronously call the syncfs syscall to sync the filesystem associated
		1298	to the given filehandle and call the callback with the syncfs result
		1299	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1300	errno to C<ENOSYS> nevertheless.
1059		1301
1060	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1302	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1061		1303
1062	Sync the data portion of the file specified by C<$offset> and C<$length>	1304	Sync the data portion of the file specified by C<$offset> and C<$length>
1063	to disk (but NOT the metadata), by calling the Linux-specific	1305	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1067	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1309	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1068	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1310	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1069	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1311	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1070	manpage for details.	1312	manpage for details.
1071		1313
1072	=item aio_pathsync $path, $callback->($status)	1314	=item aio_pathsync $pathname, $callback->($status)
1073		1315
1074	This request tries to open, fsync and close the given path. This is a	1316	This request tries to open, fsync and close the given path. This is a
1075	composite request intended to sync directories after directory operations	1317	composite request intended to sync directories after directory operations
1076	(E.g. rename). This might not work on all operating systems or have any	1318	(E.g. rename). This might not work on all operating systems or have any
1077	specific effect, but usually it makes sure that directory changes get	1319	specific effect, but usually it makes sure that directory changes get
…		…
1108	};	1350	};
1109		1351
1110	$grp	1352	$grp
1111	}	1353	}
1112		1354
1113	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1355	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1114		1356
1115	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1357	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1116	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1358	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1117	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1359	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1118	scalar must only be modified in-place while an aio operation is pending on	1360	scalar must only be modified in-place while an aio operation is pending on
…		…
1120		1362
1121	It calls the C<msync> function of your OS, if available, with the memory	1363	It calls the C<msync> function of your OS, if available, with the memory
1122	area starting at C<$offset> in the string and ending C<$length> bytes	1364	area starting at C<$offset> in the string and ending C<$length> bytes
1123	later. If C<$length> is negative, counts from the end, and if C<$length>	1365	later. If C<$length> is negative, counts from the end, and if C<$length>
1124	is C<undef>, then it goes till the end of the string. The flags can be	1366	is C<undef>, then it goes till the end of the string. The flags can be
1125	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1367	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1126	C<IO::AIO::MS_SYNC>.	1368	C<IO::AIO::MS_INVALIDATE>.
1127		1369
1128	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1370	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1129		1371
1130	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1372	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1131	scalars.	1373	scalars.
1132		1374
1133	It touches (reads or writes) all memory pages in the specified	1375	It touches (reads or writes) all memory pages in the specified
1134	range inside the scalar. All caveats and parameters are the same	1376	range inside the scalar. All caveats and parameters are the same
1135	as for C<aio_msync>, above, except for flags, which must be either	1377	as for C<aio_msync>, above, except for flags, which must be either
1136	C<0> (which reads all pages and ensures they are instantiated) or	1378	C<0> (which reads all pages and ensures they are instantiated) or
1137	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1379	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1138	writing an octet from it, which dirties the page).	1380	writing an octet from it, which dirties the page).
1139		1381
1140	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1382	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1141		1383
1142	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1384	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1173	documented under L<MISCELLANEOUS FUNCTIONS>.	1415	documented under L<MISCELLANEOUS FUNCTIONS>.
1174		1416
1175	Example: asynchronously lock all current and future pages into memory.	1417	Example: asynchronously lock all current and future pages into memory.
1176		1418
1177	aio_mlockall IO::AIO::MCL_FUTURE;	1419	aio_mlockall IO::AIO::MCL_FUTURE;
		1420
		1421	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1422
		1423	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1424	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1425	the ioctl is not available on your OS, then this request will fail with
		1426	C<ENOSYS>.
		1427
		1428	C<$start> is the starting offset to query extents for, C<$length> is the
		1429	size of the range to query - if it is C<undef>, then the whole file will
		1430	be queried.
		1431
		1432	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1433	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1434	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1435	the data portion.
		1436
		1437	C<$count> is the maximum number of extent records to return. If it is
		1438	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1439	case, if it is C<0>, then the callback receives the number of extents
		1440	instead of the extents themselves (which is unreliable, see below).
		1441
		1442	If an error occurs, the callback receives no arguments. The special
		1443	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1444
		1445	Otherwise, the callback receives an array reference with extent
		1446	structures. Each extent structure is an array reference itself, with the
		1447	following members:
		1448
		1449	[$logical, $physical, $length, $flags]
		1450
		1451	Flags is any combination of the following flag values (typically either C<0>
		1452	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1453
		1454	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1455	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1456	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1457	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1458	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1459	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1460
		1461	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1462	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1463	it to return all extents of a range for files with large number of
		1464	extents. The code works around all these issues if C<$count> is undef.
1178		1465
1179	=item aio_group $callback->(...)	1466	=item aio_group $callback->(...)
1180		1467
1181	This is a very special aio request: Instead of doing something, it is a	1468	This is a very special aio request: Instead of doing something, it is a
1182	container for other aio requests, which is useful if you want to bundle	1469	container for other aio requests, which is useful if you want to bundle
…		…
1219	like sleep and file handle readable/writable, the overhead this creates is	1506	like sleep and file handle readable/writable, the overhead this creates is
1220	immense (it blocks a thread for a long time) so do not use this function	1507	immense (it blocks a thread for a long time) so do not use this function
1221	except to put your application under artificial I/O pressure.	1508	except to put your application under artificial I/O pressure.
1222		1509
1223	=back	1510	=back
		1511
		1512
		1513	=head2 IO::AIO::WD - multiple working directories
		1514
		1515	Your process only has one current working directory, which is used by all
		1516	threads. This makes it hard to use relative paths (some other component
		1517	could call C<chdir> at any time, and it is hard to control when the path
		1518	will be used by IO::AIO).
		1519
		1520	One solution for this is to always use absolute paths. This usually works,
		1521	but can be quite slow (the kernel has to walk the whole path on every
		1522	access), and can also be a hassle to implement.
		1523
		1524	Newer POSIX systems have a number of functions (openat, fdopendir,
		1525	futimensat and so on) that make it possible to specify working directories
		1526	per operation.
		1527
		1528	For portability, and because the clowns who "designed", or shall I write,
		1529	perpetrated this new interface were obviously half-drunk, this abstraction
		1530	cannot be perfect, though.
		1531
		1532	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1533	object. This object stores the canonicalised, absolute version of the
		1534	path, and on systems that allow it, also a directory file descriptor.
		1535
		1536	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1537	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1538	object and a pathname instead (or the IO::AIO::WD object alone, which
		1539	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1540	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1541	to that IO::AIO::WD object.
		1542
		1543	For example, to get a wd object for F</etc> and then stat F<passwd>
		1544	inside, you would write:
		1545
		1546	aio_wd "/etc", sub {
		1547	my $etcdir = shift;
		1548
		1549	# although $etcdir can be undef on error, there is generally no reason
		1550	# to check for errors here, as aio_stat will fail with ENOENT
		1551	# when $etcdir is undef.
		1552
		1553	aio_stat [$etcdir, "passwd"], sub {
		1554	# yay
		1555	};
		1556	};
		1557
		1558	The fact that C<aio_wd> is a request and not a normal function shows that
		1559	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1560	which is why it is done asynchronously.
		1561
		1562	To stat the directory obtained with C<aio_wd> above, one could write
		1563	either of the following three request calls:
		1564
		1565	aio_lstat "/etc" , sub { ... # pathname as normal string
		1566	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1567	aio_lstat $wd , sub { ... # shorthand for the previous
		1568
		1569	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1570	object and the pathname string, so you could write the following without
		1571	causing any issues due to C<$path> getting reused:
		1572
		1573	my $path = [$wd, undef];
		1574
		1575	for my $name (qw(abc def ghi)) {
		1576	$path->[1] = $name;
		1577	aio_stat $path, sub {
		1578	# ...
		1579	};
		1580	}
		1581
		1582	There are some caveats: when directories get renamed (or deleted), the
		1583	pathname string doesn't change, so will point to the new directory (or
		1584	nowhere at all), while the directory fd, if available on the system,
		1585	will still point to the original directory. Most functions accepting a
		1586	pathname will use the directory fd on newer systems, and the string on
		1587	older systems. Some functions (such as realpath) will always rely on the
		1588	string form of the pathname.
		1589
		1590	So this functionality is mainly useful to get some protection against
		1591	C<chdir>, to easily get an absolute path out of a relative path for future
		1592	reference, and to speed up doing many operations in the same directory
		1593	(e.g. when stat'ing all files in a directory).
		1594
		1595	The following functions implement this working directory abstraction:
		1596
		1597	=over 4
		1598
		1599	=item aio_wd $pathname, $callback->($wd)
		1600
		1601	Asynchonously canonicalise the given pathname and convert it to an
		1602	IO::AIO::WD object representing it. If possible and supported on the
		1603	system, also open a directory fd to speed up pathname resolution relative
		1604	to this working directory.
		1605
		1606	If something goes wrong, then C<undef> is passwd to the callback instead
		1607	of a working directory object and C<$!> is set appropriately. Since
		1608	passing C<undef> as working directory component of a pathname fails the
		1609	request with C<ENOENT>, there is often no need for error checking in the
		1610	C<aio_wd> callback, as future requests using the value will fail in the
		1611	expected way.
		1612
		1613	=item IO::AIO::CWD
		1614
		1615	This is a compiletime constant (object) that represents the process
		1616	current working directory.
		1617
		1618	Specifying this object as working directory object for a pathname is as if
		1619	the pathname would be specified directly, without a directory object. For
		1620	example, these calls are functionally identical:
		1621
		1622	aio_stat "somefile", sub { ... };
		1623	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1624
		1625	=back
		1626
		1627	To recover the path associated with an IO::AIO::WD object, you can use
		1628	C<aio_realpath>:
		1629
		1630	aio_realpath $wd, sub {
		1631	warn "path is $_[0]\n";
		1632	};
		1633
		1634	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1635	sometimes, fall back to using an absolue path.
1224		1636
1225	=head2 IO::AIO::REQ CLASS	1637	=head2 IO::AIO::REQ CLASS
1226		1638
1227	All non-aggregate C<aio_*> functions return an object of this class when	1639	All non-aggregate C<aio_*> functions return an object of this class when
1228	called in non-void context.	1640	called in non-void context.
…		…
1346		1758
1347	Sets a feeder/generator on this group: every group can have an attached	1759	Sets a feeder/generator on this group: every group can have an attached
1348	generator that generates requests if idle. The idea behind this is that,	1760	generator that generates requests if idle. The idea behind this is that,
1349	although you could just queue as many requests as you want in a group,	1761	although you could just queue as many requests as you want in a group,
1350	this might starve other requests for a potentially long time. For example,	1762	this might starve other requests for a potentially long time. For example,
1351	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1763	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1352	delaying any later requests for a long time.	1764	requests, delaying any later requests for a long time.
1353		1765
1354	To avoid this, and allow incremental generation of requests, you can	1766	To avoid this, and allow incremental generation of requests, you can
1355	instead a group and set a feeder on it that generates those requests. The	1767	instead a group and set a feeder on it that generates those requests. The
1356	feed callback will be called whenever there are few enough (see C<limit>,	1768	feed callback will be called whenever there are few enough (see C<limit>,
1357	below) requests active in the group itself and is expected to queue more	1769	below) requests active in the group itself and is expected to queue more
…		…
1406		1818
1407	See C<poll_cb> for an example.	1819	See C<poll_cb> for an example.
1408		1820
1409	=item IO::AIO::poll_cb	1821	=item IO::AIO::poll_cb
1410		1822
1411	Process some outstanding events on the result pipe. You have to call	1823	Process some requests that have reached the result phase (i.e. they have
		1824	been executed but the results are not yet reported). You have to call
		1825	this "regularly" to finish outstanding requests.
		1826
1412	this regularly. Returns C<0> if all events could be processed (or there	1827	Returns C<0> if all events could be processed (or there were no
1413	were no events to process), or C<-1> if it returned earlier for whatever	1828	events to process), or C<-1> if it returned earlier for whatever
1414	reason. Returns immediately when no events are outstanding. The amount of	1829	reason. Returns immediately when no events are outstanding. The amount
1415	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1830	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1416	C<IO::AIO::max_poll_time>.	1831	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1417		1832
1418	If not all requests were processed for whatever reason, the filehandle	1833	If not all requests were processed for whatever reason, the poll file
1419	will still be ready when C<poll_cb> returns, so normally you don't have to	1834	descriptor will still be ready when C<poll_cb> returns, so normally you
1420	do anything special to have it called later.	1835	don't have to do anything special to have it called later.
1421		1836
1422	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1837	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1423	ready, it can be beneficial to call this function from loops which submit	1838	ready, it can be beneficial to call this function from loops which submit
1424	a lot of requests, to make sure the results get processed when they become	1839	a lot of requests, to make sure the results get processed when they become
1425	available and not just when the loop is finished and the event loop takes	1840	available and not just when the loop is finished and the event loop takes
…		…
1434	poll => 'r', async => 1,	1849	poll => 'r', async => 1,
1435	cb => \&IO::AIO::poll_cb);	1850	cb => \&IO::AIO::poll_cb);
1436		1851
1437	=item IO::AIO::poll_wait	1852	=item IO::AIO::poll_wait
1438		1853
1439	If there are any outstanding requests and none of them in the result	1854	Wait until either at least one request is in the result phase or no
1440	phase, wait till the result filehandle becomes ready for reading (simply	1855	requests are outstanding anymore.
1441	does a C<select> on the filehandle. This is useful if you want to	1856
1442	synchronously wait for some requests to finish).	1857	This is useful if you want to synchronously wait for some requests to
		1858	become ready, without actually handling them.
1443		1859
1444	See C<nreqs> for an example.	1860	See C<nreqs> for an example.
1445		1861
1446	=item IO::AIO::poll	1862	=item IO::AIO::poll
1447		1863
…		…
1555	Sets the minimum idle timeout (default 10) after which worker threads are	1971	Sets the minimum idle timeout (default 10) after which worker threads are
1556	allowed to exit. SEe C<IO::AIO::max_idle>.	1972	allowed to exit. SEe C<IO::AIO::max_idle>.
1557		1973
1558	=item IO::AIO::max_outstanding $maxreqs	1974	=item IO::AIO::max_outstanding $maxreqs
1559		1975
		1976	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1977	you do queue up more than this number of requests, the next call to
		1978	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1979	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1980	longer exceeded.
		1981
		1982	In other words, this setting does not enforce a queue limit, but can be
		1983	used to make poll functions block if the limit is exceeded.
		1984
1560	This is a very bad function to use in interactive programs because it	1985	This is a very bad function to use in interactive programs because it
1561	blocks, and a bad way to reduce concurrency because it is inexact: Better	1986	blocks, and a bad way to reduce concurrency because it is inexact: Better
1562	use an C<aio_group> together with a feed callback.	1987	use an C<aio_group> together with a feed callback.
1563		1988
1564	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1989	Its main use is in scripts without an event loop - when you want to stat
1565	do queue up more than this number of requests, the next call to the	1990	a lot of files, you can write somehting like this:
1566	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1567	function will block until the limit is no longer exceeded.
1568		1991
1569	The default value is very large, so there is no practical limit on the	1992	IO::AIO::max_outstanding 32;
1570	number of outstanding requests.
1571		1993
1572	You can still queue as many requests as you want. Therefore,	1994	for my $path (...) {
1573	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1995	aio_stat $path , ...;
1574	as a stop gap to shield against fatal memory overflow (with large values).	1996	IO::AIO::poll_cb;
		1997	}
		1998
		1999	IO::AIO::flush;
		2000
		2001	The call to C<poll_cb> inside the loop will normally return instantly, but
		2002	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2003	some requests have been handled. This keeps the loop from pushing a large
		2004	number of C<aio_stat> requests onto the queue.
		2005
		2006	The default value for C<max_outstanding> is very large, so there is no
		2007	practical limit on the number of outstanding requests.
1575		2008
1576	=back	2009	=back
1577		2010
1578	=head3 STATISTICAL INFORMATION	2011	=head3 STATISTICAL INFORMATION
1579		2012
…		…
1601		2034
1602	=back	2035	=back
1603		2036
1604	=head3 MISCELLANEOUS FUNCTIONS	2037	=head3 MISCELLANEOUS FUNCTIONS
1605		2038
1606	IO::AIO implements some functions that might be useful, but are not	2039	IO::AIO implements some functions that are useful when you want to use
1607	asynchronous.	2040	some "Advanced I/O" function not available to in Perl, without going the
		2041	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2042	counterpart.
1608		2043
1609	=over 4	2044	=over 4
1610		2045
1611	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2046	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1612		2047
…		…
1619		2054
1620	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2055	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1621		2056
1622	Simply calls the C<posix_fadvise> function (see its	2057	Simply calls the C<posix_fadvise> function (see its
1623	manpage for details). The following advice constants are	2058	manpage for details). The following advice constants are
1624	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2059	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1625	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2060	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1626	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2061	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1627		2062
1628	On systems that do not implement C<posix_fadvise>, this function returns	2063	On systems that do not implement C<posix_fadvise>, this function returns
1629	ENOSYS, otherwise the return value of C<posix_fadvise>.	2064	ENOSYS, otherwise the return value of C<posix_fadvise>.
1630		2065
1631	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2066	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1632		2067
1633	Simply calls the C<posix_madvise> function (see its	2068	Simply calls the C<posix_madvise> function (see its
1634	manpage for details). The following advice constants are	2069	manpage for details). The following advice constants are
1635	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2070	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1636	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2071	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
		2072	C<IO::AIO::MADV_FREE>.
1637		2073
1638	On systems that do not implement C<posix_madvise>, this function returns	2074	On systems that do not implement C<posix_madvise>, this function returns
1639	ENOSYS, otherwise the return value of C<posix_madvise>.	2075	ENOSYS, otherwise the return value of C<posix_madvise>.
1640		2076
1641	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2077	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1642		2078
1643	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2079	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1644	$scalar (see its manpage for details). The following protect	2080	$scalar (see its manpage for details). The following protect
1645	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2081	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1646	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2082	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1647		2083
1648	On systems that do not implement C<mprotect>, this function returns	2084	On systems that do not implement C<mprotect>, this function returns
1649	ENOSYS, otherwise the return value of C<mprotect>.	2085	ENOSYS, otherwise the return value of C<mprotect>.
1650		2086
1651	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2087	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1652		2088
1653	Memory-maps a file (or anonymous memory range) and attaches it to the	2089	Memory-maps a file (or anonymous memory range) and attaches it to the
1654	given C<$scalar>, which will act like a string scalar.	2090	given C<$scalar>, which will act like a string scalar. Returns true on
		2091	success, and false otherwise.
1655		2092
		2093	The scalar must exist, but its contents do not matter - this means you
		2094	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2095	the scalar first.
		2096
1656	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2097	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1657	change the string length, and most read-only operations such as copying it	2098	which don't change the string length, and most read-only operations such
1658	or searching it with regexes and so on.	2099	as copying it or searching it with regexes and so on.
1659		2100
1660	Anything else is unsafe and will, at best, result in memory leaks.	2101	Anything else is unsafe and will, at best, result in memory leaks.
1661		2102
1662	The memory map associated with the C<$scalar> is automatically removed	2103	The memory map associated with the C<$scalar> is automatically removed
1663	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2104	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1664	C<IO::AIO::munmap> functions are called.	2105	or C<IO::AIO::munmap> functions are called on it.
1665		2106
1666	This calls the C<mmap>(2) function internally. See your system's manual	2107	This calls the C<mmap>(2) function internally. See your system's manual
1667	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2108	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1668		2109
1669	The C<$length> must be larger than zero and smaller than the actual	2110	The C<$length> must be larger than zero and smaller than the actual
1670	filesize.	2111	filesize.
1671		2112
1672	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2113	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1673	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2114	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1674		2115
1675	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2116	C<$flags> can be a combination of
1676	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2117	C<IO::AIO::MAP_SHARED> or
1677	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2118	C<IO::AIO::MAP_PRIVATE>,
		2119	or a number of system-specific flags (when not available, the are C<0>):
1678	(which is set to C<MAP_ANON> if your system only provides this	2120	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1679	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2121	C<IO::AIO::MAP_LOCKED>,
1680	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2122	C<IO::AIO::MAP_NORESERVE>,
		2123	C<IO::AIO::MAP_POPULATE>,
1681	C<IO::AIO::MAP_NONBLOCK>	2124	C<IO::AIO::MAP_NONBLOCK>,
		2125	C<IO::AIO::MAP_FIXED>,
		2126	C<IO::AIO::MAP_GROWSDOWN>,
		2127	C<IO::AIO::MAP_32BIT>,
		2128	C<IO::AIO::MAP_HUGETLB> or
		2129	C<IO::AIO::MAP_STACK>.
1682		2130
1683	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2131	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1684		2132
1685	C<$offset> is the offset from the start of the file - it generally must be	2133	C<$offset> is the offset from the start of the file - it generally must be
1686	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2134	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1711		2159
1712	Calls the C<munlockall> function.	2160	Calls the C<munlockall> function.
1713		2161
1714	On systems that do not implement C<munlockall>, this function returns	2162	On systems that do not implement C<munlockall>, this function returns
1715	ENOSYS, otherwise the return value of C<munlockall>.	2163	ENOSYS, otherwise the return value of C<munlockall>.
		2164
		2165	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2166
		2167	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2168	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2169	should be the file offset.
		2170
		2171	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2172	silently corrupt the data in this case.
		2173
		2174	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2175	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2176	C<IO::AIO::SPLICE_F_GIFT>.
		2177
		2178	See the C<splice(2)> manpage for details.
		2179
		2180	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2181
		2182	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2183	description for C<IO::AIO::splice> above for details.
		2184
		2185	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2186
		2187	Attempts to query or change the pipe buffer size. Obviously works only
		2188	on pipes, and currently works only on GNU/Linux systems, and fails with
		2189	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2190	size on other systems, drop me a note.
		2191
		2192	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2193
		2194	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2195	C<$flags> is missing or C<0>, then this should be the same as a call to
		2196	perl's built-in C<pipe> function and create a new pipe, and works on
		2197	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2198	(..., 4096, O_BINARY)>.
		2199
		2200	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2201	the given flags (Linux 2.6.27, glibc 2.9).
		2202
		2203	On success, the read and write file handles are returned.
		2204
		2205	On error, nothing will be returned. If the pipe2 syscall is missing and
		2206	C<$flags> is non-zero, fails with C<ENOSYS>.
		2207
		2208	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2209	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2210	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1716		2211
1717	=back	2212	=back
1718		2213
1719	=cut	2214	=cut
1720		2215
…		…
1755	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2250	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1756	\&IO::AIO::poll_cb);	2251	\&IO::AIO::poll_cb);
1757		2252
1758	=head2 FORK BEHAVIOUR	2253	=head2 FORK BEHAVIOUR
1759		2254
1760	This module should do "the right thing" when the process using it forks:	2255	Usage of pthreads in a program changes the semantics of fork
		2256	considerably. Specifically, only async-safe functions can be called after
		2257	fork. Perl doesn't know about this, so in general, you cannot call fork
		2258	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2259	pthreads, so this applies, but many other extensions and (for inexplicable
		2260	reasons) perl itself often is linked against pthreads, so this limitation
		2261	applies to quite a lot of perls.
1761		2262
1762	Before the fork, IO::AIO enters a quiescent state where no requests	2263	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1763	can be added in other threads and no results will be processed. After	2264	only works in the process that loaded it. Forking is fully supported, but
1764	the fork the parent simply leaves the quiescent state and continues	2265	using IO::AIO in the child is not.
1765	request/result processing, while the child frees the request/result queue
1766	(so that the requests started before the fork will only be handled in the
1767	parent). Threads will be started on demand until the limit set in the
1768	parent process has been reached again.
1769		2266
1770	In short: the parent will, after a short pause, continue as if fork had	2267	You might get around by not I<using> IO::AIO before (or after)
1771	not been called, while the child will act as if IO::AIO has not been used	2268	forking. You could also try to call the L<IO::AIO::reinit> function in the
1772	yet.	2269	child:
		2270
		2271	=over 4
		2272
		2273	=item IO::AIO::reinit
		2274
		2275	Abandons all current requests and I/O threads and simply reinitialises all
		2276	data structures. This is not an operation supported by any standards, but
		2277	happens to work on GNU/Linux and some newer BSD systems.
		2278
		2279	The only reasonable use for this function is to call it after forking, if
		2280	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2281	the process will result in undefined behaviour. Calling it at any time
		2282	will also result in any undefined (by POSIX) behaviour.
		2283
		2284	=back
1773		2285
1774	=head2 MEMORY USAGE	2286	=head2 MEMORY USAGE
1775		2287
1776	Per-request usage:	2288	Per-request usage:
1777		2289

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.193 by root, Thu May 26 04:15:37 2011 UTC vs. Revision 1.268 by root, Tue May 30 22:45:52 2017 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.193 by root, Thu May 26 04:15:37 2011 UTC vs.
Revision 1.268 by root, Tue May 30 22:45:52 2017 UTC