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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.187 by root, Fri Feb 11 00:05:17 2011 UTC vs.
Revision 1.267 by root, Tue Aug 9 11:39:17 2016 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '3.72';	176	our $VERSION = 4.34;
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	192	min_parallel max_parallel max_idle idle_timeout
188	nreqs nready npending nthreads	193	nreqs nready npending nthreads
189	max_poll_time max_poll_reqs	194	max_poll_time max_poll_reqs
190	sendfile fadvise madvise	195	sendfile fadvise madvise
191	mmap munmap munlock munlockall);	196	mmap munmap munlock munlockall);
192		197
…		…
200		205
201	=head1 FUNCTIONS	206	=head1 FUNCTIONS
202		207
203	=head2 QUICK OVERVIEW	208	=head2 QUICK OVERVIEW
204		209
205	This section simply lists the prototypes of the most important functions	210	This section simply lists the prototypes most of the functions for
206	for quick reference. See the following sections for function-by-function	211	quick reference. See the following sections for function-by-function
207	documentation.	212	documentation.
208		213
		214	aio_wd $pathname, $callback->($wd)
209	aio_open $pathname, $flags, $mode, $callback->($fh)	215	aio_open $pathname, $flags, $mode, $callback->($fh)
210	aio_close $fh, $callback->($status)	216	aio_close $fh, $callback->($status)
		217	aio_seek $fh,$offset,$whence, $callback->($offs)
211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	218	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	220	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214	aio_readahead $fh,$offset,$length, $callback->($retval)	221	aio_readahead $fh,$offset,$length, $callback->($retval)
215	aio_stat $fh_or_path, $callback->($status)	222	aio_stat $fh_or_path, $callback->($status)
216	aio_lstat $fh, $callback->($status)	223	aio_lstat $fh, $callback->($status)
217	aio_statvfs $fh_or_path, $callback->($statvfs)	224	aio_statvfs $fh_or_path, $callback->($statvfs)
218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	225	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	226	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		227	aio_chmod $fh_or_path, $mode, $callback->($status)
220	aio_truncate $fh_or_path, $offset, $callback->($status)	228	aio_truncate $fh_or_path, $offset, $callback->($status)
221	aio_chmod $fh_or_path, $mode, $callback->($status)	229	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		230	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
222	aio_unlink $pathname, $callback->($status)	231	aio_unlink $pathname, $callback->($status)
223	aio_mknod $path, $mode, $dev, $callback->($status)	232	aio_mknod $pathname, $mode, $dev, $callback->($status)
224	aio_link $srcpath, $dstpath, $callback->($status)	233	aio_link $srcpath, $dstpath, $callback->($status)
225	aio_symlink $srcpath, $dstpath, $callback->($status)	234	aio_symlink $srcpath, $dstpath, $callback->($status)
226	aio_readlink $path, $callback->($link)	235	aio_readlink $pathname, $callback->($link)
		236	aio_realpath $pathname, $callback->($path)
227	aio_rename $srcpath, $dstpath, $callback->($status)	237	aio_rename $srcpath, $dstpath, $callback->($status)
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 = 0, $callback->($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->(...)
…		…
258	IO::AIO::max_poll_reqs $nreqs	271	IO::AIO::max_poll_reqs $nreqs
259	IO::AIO::max_poll_time $seconds	272	IO::AIO::max_poll_time $seconds
260	IO::AIO::min_parallel $nthreads	273	IO::AIO::min_parallel $nthreads
261	IO::AIO::max_parallel $nthreads	274	IO::AIO::max_parallel $nthreads
262	IO::AIO::max_idle $nthreads	275	IO::AIO::max_idle $nthreads
		276	IO::AIO::idle_timeout $seconds
263	IO::AIO::max_outstanding $maxreqs	277	IO::AIO::max_outstanding $maxreqs
264	IO::AIO::nreqs	278	IO::AIO::nreqs
265	IO::AIO::nready	279	IO::AIO::nready
266	IO::AIO::npending	280	IO::AIO::npending
267		281
268	IO::AIO::sendfile $ofh, $ifh, $offset, $count	282	IO::AIO::sendfile $ofh, $ifh, $offset, $count
269	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
270	IO::AIO::madvise $scalar, $offset, $length, $advice	286	IO::AIO::madvise $scalar, $offset, $length, $advice
271	IO::AIO::mprotect $scalar, $offset, $length, $protect	287	IO::AIO::mprotect $scalar, $offset, $length, $protect
272	IO::AIO::munlock $scalar, $offset = 0, $length = undef	288	IO::AIO::munlock $scalar, $offset = 0, $length = undef
273	IO::AIO::munlockall	289	IO::AIO::munlockall
274		290
275	=head2 AIO REQUEST FUNCTIONS	291	=head2 API NOTES
276		292
277	All the C<aio_*> calls are more or less thin wrappers around the syscall	293	All the C<aio_*> calls are more or less thin wrappers around the syscall
278	with the same name (sans C<aio_>). The arguments are similar or identical,	294	with the same name (sans C<aio_>). The arguments are similar or identical,
279	and they all accept an additional (and optional) C<$callback> argument	295	and they all accept an additional (and optional) C<$callback> argument
280	which must be a code reference. This code reference will get called with	296	which must be a code reference. This code reference will be called after
281	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	297	the syscall has been executed in an asynchronous fashion. The results
282	perl, which usually delivers "false") as its sole argument after the given	298	of the request will be passed as arguments to the callback (and, if an
283	syscall has been executed asynchronously.	299	error occured, in C<$!>) - 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>.
284		305
285	All functions expecting a filehandle keep a copy of the filehandle	306	All functions expecting a filehandle keep a copy of the filehandle
286	internally until the request has finished.	307	internally until the request has finished.
287		308
288	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
289	further manipulation of those requests while they are in-flight.	310	further manipulation of those requests while they are in-flight.
290		311
291	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
292	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
293	request is being executed, the current working directory could have	314	current working directory could have changed. Alternatively, you can
294	changed. Alternatively, you can make sure that you never change the	315	make sure that you never change the current working directory anywhere
295	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
296	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.
297		320
298	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
299	in filenames you got from outside (command line, readdir etc.) without	322	in filenames you got from outside (command line, readdir etc.) without
300	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	323	tinkering, b) are in your native filesystem encoding, c) use the Encode
301	your pathnames to the locale (or other) encoding in effect in the user	324	module and encode your pathnames to the locale (or other) encoding in
302	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	325	effect in the user environment, d) use Glib::filename_from_unicode on
303	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.
304		328
305	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
306	handles correctly whether it is set or not.	330	handles correctly whether it is set or not.
		331
		332	=head2 AIO REQUEST FUNCTIONS
307		333
308	=over 4	334	=over 4
309		335
310	=item $prev_pri = aioreq_pri [$pri]	336	=item $prev_pri = aioreq_pri [$pri]
311		337
…		…
341		367
342		368
343	=item aio_open $pathname, $flags, $mode, $callback->($fh)	369	=item aio_open $pathname, $flags, $mode, $callback->($fh)
344		370
345	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
346	created filehandle for the file.	372	created filehandle for the file (or C<undef> in case of an error).
347		373
348	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,
349	for an explanation.	375	for an explanation.
350		376
351	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
…		…
367	} else {	393	} else {
368	die "open failed: $!\n";	394	die "open failed: $!\n";
369	}	395	}
370	};	396	};
371		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
372		407
373	=item aio_close $fh, $callback->($status)	408	=item aio_close $fh, $callback->($status)
374		409
375	Asynchronously close a file and call the callback with the result	410	Asynchronously close a file and call the callback with the result
376	code.	411	code.
…		…
385	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
386	free for reuse until the perl filehandle is closed.	421	free for reuse until the perl filehandle is closed.
387		422
388	=cut	423	=cut
389		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
390	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	445	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
391		446
392	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	447	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
393		448
394	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
395	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
396	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
397	error, just like the syscall).	452	error, just like the syscall).
398		453
399	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
400	offset plus the actual number of bytes read.	455	offset plus the actual number of bytes read.
401		456
…		…
426		481
427	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
428	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
429	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
430	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
431	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>.
432		488
433	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
434	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
435	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
436	bytes written to C<$out_fh>. Only if the result value equals C<$length>	492	number of bytes written to C<$out_fh>. Only if the result value equals
437	one can assume that C<$length> bytes have been read.	493	C<$length> one can assume that C<$length> bytes have been read.
438		494
439	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
440	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
441	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
442	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
443	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
444	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
445	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
446	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
447	much better.	503	resource usage.
448		504
449	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
450	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
451	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.
452		508
453	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>,
454	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	510	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
455	it will be emulated, so you can call C<aio_sendfile> on any type of	511	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
456	filehandle regardless of the limitations of the operating system.	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.
457		520
458		521
459	=item aio_readahead $fh,$offset,$length, $callback->($retval)	522	=item aio_readahead $fh,$offset,$length, $callback->($retval)
460		523
461	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
…		…
465	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
466	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
467	(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
468	file. The current file offset of the file is left unchanged.	531	file. The current file offset of the file is left unchanged.
469		532
470	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
471	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.
472		535
473		536
474	=item aio_stat $fh_or_path, $callback->($status)	537	=item aio_stat $fh_or_path, $callback->($status)
475		538
476	=item aio_lstat $fh, $callback->($status)	539	=item aio_lstat $fh, $callback->($status)
…		…
545	namemax => 255,	608	namemax => 255,
546	frsize => 1024,	609	frsize => 1024,
547	fsid => 1810	610	fsid => 1810
548	}	611	}
549		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
550		697
551	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	698	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
552		699
553	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
554	and $mtime being undef). Fractional times are supported if the underlying	701	and $mtime being undef). Fractional times are supported if the underlying
…		…
582	=item aio_truncate $fh_or_path, $offset, $callback->($status)	729	=item aio_truncate $fh_or_path, $offset, $callback->($status)
583		730
584	Works like truncate(2) or ftruncate(2).	731	Works like truncate(2) or ftruncate(2).
585		732
586		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
587	=item aio_chmod $fh_or_path, $mode, $callback->($status)	754	=item aio_chmod $fh_or_path, $mode, $callback->($status)
588		755
589	Works like perl's C<chmod> function.	756	Works like perl's C<chmod> function.
590		757
591		758
…		…
593		760
594	Asynchronously unlink (delete) a file and call the callback with the	761	Asynchronously unlink (delete) a file and call the callback with the
595	result code.	762	result code.
596		763
597		764
598	=item aio_mknod $path, $mode, $dev, $callback->($status)	765	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
599		766
600	[EXPERIMENTAL]	767	[EXPERIMENTAL]
601		768
602	Asynchronously create a device node (or fifo). See mknod(2).	769	Asynchronously create a device node (or fifo). See mknod(2).
603		770
604	The only (POSIX-) portable way of calling this function is:	771	The only (POSIX-) portable way of calling this function is:
605		772
606	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	773	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
607		774
608	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
609	and functions.	776	and functions.
610		777
611	=item aio_link $srcpath, $dstpath, $callback->($status)	778	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
618		785
619	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
620	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.
621		788
622		789
623	=item aio_readlink $path, $callback->($link)	790	=item aio_readlink $pathname, $callback->($link)
624		791
625	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
626	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
627	callback.	794	callback.
628		795
629		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
630	=item aio_rename $srcpath, $dstpath, $callback->($status)	807	=item aio_rename $srcpath, $dstpath, $callback->($status)
631		808
632	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
633	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>.
634		815
635		816
636	=item aio_mkdir $pathname, $mode, $callback->($status)	817	=item aio_mkdir $pathname, $mode, $callback->($status)
637		818
638	Asynchronously mkdir (create) a directory and call the callback with	819	Asynchronously mkdir (create) a directory and call the callback with
…		…
643	=item aio_rmdir $pathname, $callback->($status)	824	=item aio_rmdir $pathname, $callback->($status)
644		825
645	Asynchronously rmdir (delete) a directory and call the callback with the	826	Asynchronously rmdir (delete) a directory and call the callback with the
646	result code.	827	result code.
647		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
648		833
649	=item aio_readdir $pathname, $callback->($entries)	834	=item aio_readdir $pathname, $callback->($entries)
650		835
651	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
652	directory (i.e. opendir + readdir + closedir). The entries will not be	837	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
656	array-ref with the filenames.	841	array-ref with the filenames.
657		842
658		843
659	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	844	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
660		845
661	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	846	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
662	behaviour and output format. In case of an error, C<$entries> will be	847	tune behaviour and output format. In case of an error, C<$entries> will be
663	C<undef>.	848	C<undef>.
664		849
665	The flags are a combination of the following constants, ORed together (the	850	The flags are a combination of the following constants, ORed together (the
666	flags will also be passed to the callback, possibly modified):	851	flags will also be passed to the callback, possibly modified):
667		852
668	=over 4	853	=over 4
669		854
670	=item IO::AIO::READDIR_DENTS	855	=item IO::AIO::READDIR_DENTS
671		856
672	When this flag is off, then the callback gets an arrayref with of names	857	When this flag is off, then the callback gets an arrayref consisting of
673	only (as with C<aio_readdir>), otherwise it gets an arrayref with	858	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
674	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	859	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
675	entry in more detail.	860	entry in more detail.
676		861
677	C<$name> is the name of the entry.	862	C<$name> is the name of the entry.
678		863
…		…
691	systems that do not deliver the inode information.	876	systems that do not deliver the inode information.
692		877
693	=item IO::AIO::READDIR_DIRS_FIRST	878	=item IO::AIO::READDIR_DIRS_FIRST
694		879
695	When this flag is set, then the names will be returned in an order where	880	When this flag is set, then the names will be returned in an order where
696	likely directories come first. This is useful when you need to quickly	881	likely directories come first, in optimal stat order. This is useful when
697	find directories, or you want to find all directories while avoiding to	882	you need to quickly find directories, or you want to find all directories
698	stat() each entry.	883	while avoiding to stat() each entry.
699		884
700	If the system returns type information in readdir, then this is used	885	If the system returns type information in readdir, then this is used
701	to find directories directly. Otherwise, likely directories are files	886	to find directories directly. Otherwise, likely directories are names
702	beginning with ".", or otherwise files with no dots, of which files with	887	beginning with ".", or otherwise names with no dots, of which names with
703	short names are tried first.	888	short names are tried first.
704		889
705	=item IO::AIO::READDIR_STAT_ORDER	890	=item IO::AIO::READDIR_STAT_ORDER
706		891
707	When this flag is set, then the names will be returned in an order	892	When this flag is set, then the names will be returned in an order
…		…
714		899
715	=item IO::AIO::READDIR_FOUND_UNKNOWN	900	=item IO::AIO::READDIR_FOUND_UNKNOWN
716		901
717	This flag should not be set when calling C<aio_readdirx>. Instead, it	902	This flag should not be set when calling C<aio_readdirx>. Instead, it
718	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	903	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
719	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	904	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
720	C<$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.
721		906
722	=back	907	=back
723		908
724		909
725	=item aio_load $path, $data, $callback->($status)	910	=item aio_load $pathname, $data, $callback->($status)
726		911
727	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
728	memory. Status is the same as with aio_read.	913	memory. Status is the same as with aio_read.
729		914
730	=cut	915	=cut
…		…
852	if ($_[0] && $! == EXDEV) {	1037	if ($_[0] && $! == EXDEV) {
853	aioreq_pri $pri;	1038	aioreq_pri $pri;
854	add $grp aio_copy $src, $dst, sub {	1039	add $grp aio_copy $src, $dst, sub {
855	$grp->result ($_[0]);	1040	$grp->result ($_[0]);
856		1041
857	if (!$_[0]) {	1042	unless ($_[0]) {
858	aioreq_pri $pri;	1043	aioreq_pri $pri;
859	add $grp aio_unlink $src;	1044	add $grp aio_unlink $src;
860	}	1045	}
861	};	1046	};
862	} else {	1047	} else {
…		…
865	};	1050	};
866		1051
867	$grp	1052	$grp
868	}	1053	}
869		1054
870	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1055	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
871		1056
872	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1057	Scans a directory (similar to C<aio_readdir>) but additionally tries to
873	efficiently separate the entries of directory C<$path> into two sets of	1058	efficiently separate the entries of directory C<$path> into two sets of
874	names, directories you can recurse into (directories), and ones you cannot	1059	names, directories you can recurse into (directories), and ones you cannot
875	recurse into (everything else, including symlinks to directories).	1060	recurse into (everything else, including symlinks to directories).
…		…
906	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
907	currently) and likely non-directories (see C<aio_readdirx>). Then every	1092	currently) and likely non-directories (see C<aio_readdirx>). Then every
908	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1093	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
909	in order of their inode numbers. If that succeeds, it assumes that the	1094	in order of their inode numbers. If that succeeds, it assumes that the
910	entry is a directory or a symlink to directory (which will be checked	1095	entry is a directory or a symlink to directory (which will be checked
911	seperately). This is often faster than stat'ing the entry itself because	1096	separately). This is often faster than stat'ing the entry itself because
912	filesystems might detect the type of the entry without reading the inode	1097	filesystems might detect the type of the entry without reading the inode
913	data (e.g. ext2fs filetype feature), even on systems that cannot return	1098	data (e.g. ext2fs filetype feature), even on systems that cannot return
914	the filetype information on readdir.	1099	the filetype information on readdir.
915		1100
916	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
…		…
932		1117
933	my $grp = aio_group $cb;	1118	my $grp = aio_group $cb;
934		1119
935	$maxreq = 4 if $maxreq <= 0;	1120	$maxreq = 4 if $maxreq <= 0;
936		1121
937	# stat once	1122	# get a wd object
938	aioreq_pri $pri;	1123	aioreq_pri $pri;
939	add $grp aio_stat $path, sub {	1124	add $grp aio_wd $path, sub {
		1125	$_[0]
940	return $grp->result () if $_[0];	1126	or return $grp->result ();
941	my $now = time;
942	my $hash1 = join ":", (stat _)[0,1,3,7,9];
943		1127
944	# read the directory entries	1128	my $wd = [shift, "."];
		1129
		1130	# stat once
945	aioreq_pri $pri;	1131	aioreq_pri $pri;
946	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1132	add $grp aio_stat $wd, sub {
947	my $entries = shift
948	or return $grp->result ();	1133	return $grp->result () if $_[0];
		1134	my $now = time;
		1135	my $hash1 = join ":", (stat _)[0,1,3,7,9];
949		1136
950	# stat the dir another time	1137	# read the directory entries
951	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;
952	add $grp aio_stat $path, sub {	1145	add $grp aio_stat $wd, sub {
953	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1146	my $hash2 = join ":", (stat _)[0,1,3,7,9];
954		1147
955	my $ndirs;	1148	my $ndirs;
956		1149
957	# take the slow route if anything looks fishy	1150	# take the slow route if anything looks fishy
958	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1151	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
959	$ndirs = -1;	1152	$ndirs = -1;
960	} else {	1153	} else {
961	# if nlink == 2, we are finished	1154	# if nlink == 2, we are finished
962	# for non-posix-fs's, we rely on nlink < 2	1155	# for non-posix-fs's, we rely on nlink < 2
963	$ndirs = (stat _)[3] - 2	1156	$ndirs = (stat _)[3] - 2
964	or return $grp->result ([], $entries);	1157	or return $grp->result ([], $entries);
965	}	1158	}
966		1159
967	my (@dirs, @nondirs);	1160	my (@dirs, @nondirs);
968		1161
969	my $statgrp = add $grp aio_group sub {	1162	my $statgrp = add $grp aio_group sub {
970	$grp->result (\@dirs, \@nondirs);	1163	$grp->result (\@dirs, \@nondirs);
971	};	1164	};
972		1165
973	limit $statgrp $maxreq;	1166	limit $statgrp $maxreq;
974	feed $statgrp sub {	1167	feed $statgrp sub {
975	return unless @$entries;	1168	return unless @$entries;
976	my $entry = shift @$entries;	1169	my $entry = shift @$entries;
977		1170
978	aioreq_pri $pri;	1171	aioreq_pri $pri;
		1172	$wd->[1] = "$entry/.";
979	add $statgrp aio_stat "$path/$entry/.", sub {	1173	add $statgrp aio_stat $wd, sub {
980	if ($_[0] < 0) {	1174	if ($_[0] < 0) {
981	push @nondirs, $entry;	1175	push @nondirs, $entry;
982	} else {	1176	} else {
983	# need to check for real directory	1177	# need to check for real directory
984	aioreq_pri $pri;	1178	aioreq_pri $pri;
		1179	$wd->[1] = $entry;
985	add $statgrp aio_lstat "$path/$entry", sub {	1180	add $statgrp aio_lstat $wd, sub {
986	if (-d _) {	1181	if (-d _) {
987	push @dirs, $entry;	1182	push @dirs, $entry;
988		1183
989	unless (--$ndirs) {	1184	unless (--$ndirs) {
990	push @nondirs, @$entries;	1185	push @nondirs, @$entries;
991	feed $statgrp;	1186	feed $statgrp;
		1187	}
		1188	} else {
		1189	push @nondirs, $entry;
992	}	1190	}
993	} else {
994	push @nondirs, $entry;
995	}	1191	}
996	}	1192	}
997	}	1193	};
998	};	1194	};
999	};	1195	};
1000	};	1196	};
1001	};	1197	};
1002	};	1198	};
1003		1199
1004	$grp	1200	$grp
1005	}	1201	}
1006		1202
1007	=item aio_rmtree $path, $callback->($status)	1203	=item aio_rmtree $pathname, $callback->($status)
1008		1204
1009	Delete a directory tree starting (and including) C<$path>, return the	1205	Delete a directory tree starting (and including) C<$path>, return the
1010	status of the final C<rmdir> only. This is a composite request that	1206	status of the final C<rmdir> only. This is a composite request that
1011	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1207	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1012	everything else.	1208	everything else.
1013		1209
1014	=cut	1210	=cut
1015		1211
…		…
1037	};	1233	};
1038		1234
1039	$grp	1235	$grp
1040	}	1236	}
1041		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
1042	=item aio_sync $callback->($status)	1278	=item aio_sync $callback->($status)
1043		1279
1044	Asynchronously call sync and call the callback when finished.	1280	Asynchronously call sync and call the callback when finished.
1045		1281
1046	=item aio_fsync $fh, $callback->($status)	1282	=item aio_fsync $fh, $callback->($status)
…		…
1053	Asynchronously call fdatasync on the given filehandle and call the	1289	Asynchronously call fdatasync on the given filehandle and call the
1054	callback with the fdatasync result code.	1290	callback with the fdatasync result code.
1055		1291
1056	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
1057	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.
1058		1301
1059	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1302	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1060		1303
1061	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>
1062	to disk (but NOT the metadata), by calling the Linux-specific	1305	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1066	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1309	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1067	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1310	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1068	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
1069	manpage for details.	1312	manpage for details.
1070		1313
1071	=item aio_pathsync $path, $callback->($status)	1314	=item aio_pathsync $pathname, $callback->($status)
1072		1315
1073	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
1074	composite request intended to sync directories after directory operations	1317	composite request intended to sync directories after directory operations
1075	(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
1076	specific effect, but usually it makes sure that directory changes get	1319	specific effect, but usually it makes sure that directory changes get
…		…
1128		1371
1129	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
1130	scalars.	1373	scalars.
1131		1374
1132	It touches (reads or writes) all memory pages in the specified	1375	It touches (reads or writes) all memory pages in the specified
1133	range inside the scalar. All caveats and parameters are the same	1376	range inside the scalar. All caveats and parameters are the same
1134	as for C<aio_msync>, above, except for flags, which must be either	1377	as for C<aio_msync>, above, except for flags, which must be either
1135	C<0> (which reads all pages and ensures they are instantiated) or	1378	C<0> (which reads all pages and ensures they are instantiated) or
1136	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1379	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1137	writing an octet from it, which dirties the page).	1380	writing an octet from it, which dirties the page).
1138		1381
1139	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1382	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1140		1383
1141	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
…		…
1172	documented under L<MISCELLANEOUS FUNCTIONS>.	1415	documented under L<MISCELLANEOUS FUNCTIONS>.
1173		1416
1174	Example: asynchronously lock all current and future pages into memory.	1417	Example: asynchronously lock all current and future pages into memory.
1175		1418
1176	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.
1177		1465
1178	=item aio_group $callback->(...)	1466	=item aio_group $callback->(...)
1179		1467
1180	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
1181	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
…		…
1218	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
1219	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
1220	except to put your application under artificial I/O pressure.	1508	except to put your application under artificial I/O pressure.
1221		1509
1222	=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.
1223		1636
1224	=head2 IO::AIO::REQ CLASS	1637	=head2 IO::AIO::REQ CLASS
1225		1638
1226	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
1227	called in non-void context.	1640	called in non-void context.
…		…
1345		1758
1346	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
1347	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,
1348	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,
1349	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,
1350	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>
1351	delaying any later requests for a long time.	1764	requests, delaying any later requests for a long time.
1352		1765
1353	To avoid this, and allow incremental generation of requests, you can	1766	To avoid this, and allow incremental generation of requests, you can
1354	instead a group and set a feeder on it that generates those requests. The	1767	instead a group and set a feeder on it that generates those requests. The
1355	feed callback will be called whenever there are few enough (see C<limit>,	1768	feed callback will be called whenever there are few enough (see C<limit>,
1356	below) requests active in the group itself and is expected to queue more	1769	below) requests active in the group itself and is expected to queue more
…		…
1405		1818
1406	See C<poll_cb> for an example.	1819	See C<poll_cb> for an example.
1407		1820
1408	=item IO::AIO::poll_cb	1821	=item IO::AIO::poll_cb
1409		1822
1410	Process some outstanding events on the result pipe. You have to call this	1823	Process some requests that have reached the result phase (i.e. they have
1411	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1824	been executed but the results are not yet reported). You have to call
1412	returned earlier for whatever reason. Returns immediately when no events	1825	this "regularly" to finish outstanding requests.
1413	are outstanding. The amount of events processed depends on the settings of
1414	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1415		1826
		1827	Returns C<0> if all events could be processed (or there were no
		1828	events to process), or C<-1> if it returned earlier for whatever
		1829	reason. Returns immediately when no events are outstanding. The amount
		1830	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1831	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1832
1416	If not all requests were processed for whatever reason, the filehandle	1833	If not all requests were processed for whatever reason, the poll file
1417	will still be ready when C<poll_cb> returns, so normally you don't have to	1834	descriptor will still be ready when C<poll_cb> returns, so normally you
1418	do anything special to have it called later.	1835	don't have to do anything special to have it called later.
		1836
		1837	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1838	ready, it can be beneficial to call this function from loops which submit
		1839	a lot of requests, to make sure the results get processed when they become
		1840	available and not just when the loop is finished and the event loop takes
		1841	over again. This function returns very fast when there are no outstanding
		1842	requests.
1419		1843
1420	Example: Install an Event watcher that automatically calls	1844	Example: Install an Event watcher that automatically calls
1421	IO::AIO::poll_cb with high priority (more examples can be found in the	1845	IO::AIO::poll_cb with high priority (more examples can be found in the
1422	SYNOPSIS section, at the top of this document):	1846	SYNOPSIS section, at the top of this document):
1423		1847
…		…
1425	poll => 'r', async => 1,	1849	poll => 'r', async => 1,
1426	cb => \&IO::AIO::poll_cb);	1850	cb => \&IO::AIO::poll_cb);
1427		1851
1428	=item IO::AIO::poll_wait	1852	=item IO::AIO::poll_wait
1429		1853
1430	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
1431	phase, wait till the result filehandle becomes ready for reading (simply	1855	requests are outstanding anymore.
1432	does a C<select> on the filehandle. This is useful if you want to	1856
1433	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.
1434		1859
1435	See C<nreqs> for an example.	1860	See C<nreqs> for an example.
1436		1861
1437	=item IO::AIO::poll	1862	=item IO::AIO::poll
1438		1863
…		…
1525		1950
1526	Under normal circumstances you don't need to call this function.	1951	Under normal circumstances you don't need to call this function.
1527		1952
1528	=item IO::AIO::max_idle $nthreads	1953	=item IO::AIO::max_idle $nthreads
1529		1954
1530	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1955	Limit the number of threads (default: 4) that are allowed to idle
1531	threads that did not get a request to process within 10 seconds). That	1956	(i.e., threads that did not get a request to process within the idle
1532	means if a thread becomes idle while C<$nthreads> other threads are also	1957	timeout (default: 10 seconds). That means if a thread becomes idle while
1533	idle, it will free its resources and exit.	1958	C<$nthreads> other threads are also idle, it will free its resources and
		1959	exit.
1534		1960
1535	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1961	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1536	to allow for extremely high load situations, but want to free resources	1962	to allow for extremely high load situations, but want to free resources
1537	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1963	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1538		1964
1539	The default is probably ok in most situations, especially if thread	1965	The default is probably ok in most situations, especially if thread
1540	creation is fast. If thread creation is very slow on your system you might	1966	creation is fast. If thread creation is very slow on your system you might
1541	want to use larger values.	1967	want to use larger values.
1542		1968
		1969	=item IO::AIO::idle_timeout $seconds
		1970
		1971	Sets the minimum idle timeout (default 10) after which worker threads are
		1972	allowed to exit. SEe C<IO::AIO::max_idle>.
		1973
1543	=item IO::AIO::max_outstanding $maxreqs	1974	=item IO::AIO::max_outstanding $maxreqs
		1975
		1976	Sets the maximum number of outstanding requests to C<$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.
1544		1984
1545	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
1546	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
1547	use an C<aio_group> together with a feed callback.	1987	use an C<aio_group> together with a feed callback.
1548		1988
1549	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
1550	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:
1551	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1552	function will block until the limit is no longer exceeded.
1553		1991
1554	The default value is very large, so there is no practical limit on the	1992	IO::AIO::max_outstanding 32;
1555	number of outstanding requests.
1556		1993
1557	You can still queue as many requests as you want. Therefore,	1994	for my $path (...) {
1558	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1995	aio_stat $path , ...;
1559	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.
1560		2008
1561	=back	2009	=back
1562		2010
1563	=head3 STATISTICAL INFORMATION	2011	=head3 STATISTICAL INFORMATION
1564		2012
…		…
1586		2034
1587	=back	2035	=back
1588		2036
1589	=head3 MISCELLANEOUS FUNCTIONS	2037	=head3 MISCELLANEOUS FUNCTIONS
1590		2038
1591	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
1592	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.
1593		2043
1594	=over 4	2044	=over 4
1595		2045
1596	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2046	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1597		2047
…		…
1604		2054
1605	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2055	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1606		2056
1607	Simply calls the C<posix_fadvise> function (see its	2057	Simply calls the C<posix_fadvise> function (see its
1608	manpage for details). The following advice constants are	2058	manpage for details). The following advice constants are
1609	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2059	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1610	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2060	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1611	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2061	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1612		2062
1613	On systems that do not implement C<posix_fadvise>, this function returns	2063	On systems that do not implement C<posix_fadvise>, this function returns
1614	ENOSYS, otherwise the return value of C<posix_fadvise>.	2064	ENOSYS, otherwise the return value of C<posix_fadvise>.
1615		2065
1616	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2066	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1617		2067
1618	Simply calls the C<posix_madvise> function (see its	2068	Simply calls the C<posix_madvise> function (see its
1619	manpage for details). The following advice constants are	2069	manpage for details). The following advice constants are
1620	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2070	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1621	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2071	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
		2072	C<IO::AIO::MADV_FREE>.
1622		2073
1623	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
1624	ENOSYS, otherwise the return value of C<posix_madvise>.	2075	ENOSYS, otherwise the return value of C<posix_madvise>.
1625		2076
1626	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2077	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1627		2078
1628	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
1629	$scalar (see its manpage for details). The following protect	2080	$scalar (see its manpage for details). The following protect
1630	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>,
1631	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2082	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1632		2083
1633	On systems that do not implement C<mprotect>, this function returns	2084	On systems that do not implement C<mprotect>, this function returns
1634	ENOSYS, otherwise the return value of C<mprotect>.	2085	ENOSYS, otherwise the return value of C<mprotect>.
1635		2086
1636	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2087	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1637		2088
1638	Memory-maps a file (or anonymous memory range) and attaches it to the	2089	Memory-maps a file (or anonymous memory range) and attaches it to the
1639	given C<$scalar>, which will act like a string scalar.	2090	given C<$scalar>, which will act like a string scalar. Returns true on
		2091	success, and false otherwise.
1640		2092
1641	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2093	The only operations allowed on the scalar are C<substr>/C<vec> that don't
1642	change the string length, and most read-only operations such as copying it	2094	change the string length, and most read-only operations such as copying it
1643	or searching it with regexes and so on.	2095	or searching it with regexes and so on.
1644		2096
…		…
1655	filesize.	2107	filesize.
1656		2108
1657	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2109	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1658	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2110	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1659		2111
1660	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2112	C<$flags> can be a combination of
1661	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2113	C<IO::AIO::MAP_SHARED> or
1662	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2114	C<IO::AIO::MAP_PRIVATE>,
		2115	or a number of system-specific flags (when not available, the are C<0>):
1663	(which is set to C<MAP_ANON> if your system only provides this	2116	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1664	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2117	C<IO::AIO::MAP_LOCKED>,
1665	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2118	C<IO::AIO::MAP_NORESERVE>,
		2119	C<IO::AIO::MAP_POPULATE>,
1666	C<IO::AIO::MAP_NONBLOCK>	2120	C<IO::AIO::MAP_NONBLOCK>,
		2121	C<IO::AIO::MAP_FIXED>,
		2122	C<IO::AIO::MAP_GROWSDOWN>,
		2123	C<IO::AIO::MAP_32BIT>,
		2124	C<IO::AIO::MAP_HUGETLB> or
		2125	C<IO::AIO::MAP_STACK>.
1667		2126
1668	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2127	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1669		2128
1670	C<$offset> is the offset from the start of the file - it generally must be	2129	C<$offset> is the offset from the start of the file - it generally must be
1671	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2130	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1696		2155
1697	Calls the C<munlockall> function.	2156	Calls the C<munlockall> function.
1698		2157
1699	On systems that do not implement C<munlockall>, this function returns	2158	On systems that do not implement C<munlockall>, this function returns
1700	ENOSYS, otherwise the return value of C<munlockall>.	2159	ENOSYS, otherwise the return value of C<munlockall>.
		2160
		2161	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2162
		2163	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2164	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2165	should be the file offset.
		2166
		2167	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2168	silently corrupt the data in this case.
		2169
		2170	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2171	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2172	C<IO::AIO::SPLICE_F_GIFT>.
		2173
		2174	See the C<splice(2)> manpage for details.
		2175
		2176	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2177
		2178	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2179	description for C<IO::AIO::splice> above for details.
		2180
		2181	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2182
		2183	Attempts to query or change the pipe buffer size. Obviously works only
		2184	on pipes, and currently works only on GNU/Linux systems, and fails with
		2185	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2186	size on other systems, drop me a note.
		2187
		2188	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2189
		2190	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2191	C<$flags> is missing or C<0>, then this should be the same as a call to
		2192	perl's built-in C<pipe> function and create a new pipe, and works on
		2193	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2194	(..., 4096, O_BINARY)>.
		2195
		2196	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2197	the given flags (Linux 2.6.27, glibc 2.9).
		2198
		2199	On success, the read and write file handles are returned.
		2200
		2201	On error, nothing will be returned. If the pipe2 syscall is missing and
		2202	C<$flags> is non-zero, fails with C<ENOSYS>.
		2203
		2204	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2205	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2206	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1701		2207
1702	=back	2208	=back
1703		2209
1704	=cut	2210	=cut
1705		2211
…		…
1740	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2246	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1741	\&IO::AIO::poll_cb);	2247	\&IO::AIO::poll_cb);
1742		2248
1743	=head2 FORK BEHAVIOUR	2249	=head2 FORK BEHAVIOUR
1744		2250
1745	This module should do "the right thing" when the process using it forks:	2251	Usage of pthreads in a program changes the semantics of fork
		2252	considerably. Specifically, only async-safe functions can be called after
		2253	fork. Perl doesn't know about this, so in general, you cannot call fork
		2254	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2255	pthreads, so this applies, but many other extensions and (for inexplicable
		2256	reasons) perl itself often is linked against pthreads, so this limitation
		2257	applies to quite a lot of perls.
1746		2258
1747	Before the fork, IO::AIO enters a quiescent state where no requests	2259	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1748	can be added in other threads and no results will be processed. After	2260	only works in the process that loaded it. Forking is fully supported, but
1749	the fork the parent simply leaves the quiescent state and continues	2261	using IO::AIO in the child is not.
1750	request/result processing, while the child frees the request/result queue
1751	(so that the requests started before the fork will only be handled in the
1752	parent). Threads will be started on demand until the limit set in the
1753	parent process has been reached again.
1754		2262
1755	In short: the parent will, after a short pause, continue as if fork had	2263	You might get around by not I<using> IO::AIO before (or after)
1756	not been called, while the child will act as if IO::AIO has not been used	2264	forking. You could also try to call the L<IO::AIO::reinit> function in the
1757	yet.	2265	child:
		2266
		2267	=over 4
		2268
		2269	=item IO::AIO::reinit
		2270
		2271	Abandons all current requests and I/O threads and simply reinitialises all
		2272	data structures. This is not an operation supported by any standards, but
		2273	happens to work on GNU/Linux and some newer BSD systems.
		2274
		2275	The only reasonable use for this function is to call it after forking, if
		2276	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2277	the process will result in undefined behaviour. Calling it at any time
		2278	will also result in any undefined (by POSIX) behaviour.
		2279
		2280	=back
1758		2281
1759	=head2 MEMORY USAGE	2282	=head2 MEMORY USAGE
1760		2283
1761	Per-request usage:	2284	Per-request usage:
1762		2285

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.187 by root, Fri Feb 11 00:05:17 2011 UTC vs. Revision 1.267 by root, Tue Aug 9 11:39:17 2016 UTC

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Revision 1.187 by root, Fri Feb 11 00:05:17 2011 UTC vs.
Revision 1.267 by root, Tue Aug 9 11:39:17 2016 UTC