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Revision 1.136 by root, Tue Sep 30 14:07:59 2008 UTC vs.
Revision 1.227 by root, Tue May 29 03:58:02 2012 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my $fh = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
26	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
27		27
28	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
29	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
30		30
31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32	use AnyEvent::AIO;
33
34	# EV integration
35	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37	# Event integration
38	Event->io (fd => IO::AIO::poll_fileno,
39	poll => 'r',
40	cb => \&IO::AIO::poll_cb);
41
42	# Glib/Gtk2 integration
43	add_watch Glib::IO IO::AIO::poll_fileno,
44	in => sub { IO::AIO::poll_cb; 1 };
45
46	# Tk integration
47	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48	readable => \&IO::AIO::poll_cb);
49
50	# Danga::Socket integration
51	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52	\&IO::AIO::poll_cb);
53
54	=head1 DESCRIPTION	31	=head1 DESCRIPTION
55		32
56	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
57	operating system supports.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
58		36
59	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
60	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
61	will still block, but you can do something else in the meantime. This	39	will still block, but you can do something else in the meantime. This
62	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
66	on a RAID volume or over NFS when you do a number of stat operations	44	on a RAID volume or over NFS when you do a number of stat operations
67	concurrently.	45	concurrently.
68		46
69	While most of this works on all types of file descriptors (for	47	While most of this works on all types of file descriptors (for
70	example sockets), using these functions on file descriptors that	48	example sockets), using these functions on file descriptors that
71	support nonblocking operation (again, sockets, pipes etc.) is very	49	support nonblocking operation (again, sockets, pipes etc.) is
72	inefficient. Use an event loop for that (such as the L<Event|Event>	50	very inefficient. Use an event loop for that (such as the L<EV>
73	module): IO::AIO will naturally fit into such an event loop itself.	51	module): IO::AIO will naturally fit into such an event loop itself.
74		52
75	In this version, a number of threads are started that execute your	53	In this version, a number of threads are started that execute your
76	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
77	in perl, and the threads created by this module will not be visible	55	in perl, and the threads created by this module will not be visible
…		…
87	yourself, always call C<poll_cb> from within the same thread, or never	65	yourself, always call C<poll_cb> from within the same thread, or never
88	call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
89		67
90	=head2 EXAMPLE	68	=head2 EXAMPLE
91		69
92	This is a simple example that uses the Event module and loads	70	This is a simple example that uses the EV module and loads
93	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
94		72
95	use Fcntl;	73	use Fcntl;
96	use Event;	74	use EV;
97	use IO::AIO;	75	use IO::AIO;
98		76
99	# register the IO::AIO callback with Event	77	# register the IO::AIO callback with EV
100	Event->io (fd => IO::AIO::poll_fileno,	78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
101	poll => 'r',
102	cb => \&IO::AIO::poll_cb);
103		79
104	# queue the request to open /etc/passwd	80	# queue the request to open /etc/passwd
105	aio_open "/etc/passwd", O_RDONLY, 0, sub {	81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106	my $fh = shift	82	my $fh = shift
107	or die "error while opening: $!";	83	or die "error while opening: $!";
108		84
109	# stat'ing filehandles is generally non-blocking	85	# stat'ing filehandles is generally non-blocking
110	my $size = -s $fh;	86	my $size = -s $fh;
…		…
119		95
120	# file contents now in $contents	96	# file contents now in $contents
121	print $contents;	97	print $contents;
122		98
123	# exit event loop and program	99	# exit event loop and program
124	Event::unloop;	100	EV::unloop;
125	};	101	};
126	};	102	};
127		103
128	# possibly queue up other requests, or open GUI windows,	104	# possibly queue up other requests, or open GUI windows,
129	# check for sockets etc. etc.	105	# check for sockets etc. etc.
130		106
131	# process events as long as there are some:	107	# process events as long as there are some:
132	Event::loop;	108	EV::loop;
133		109
134	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
135		111
136	Every C<aio_*> function creates a request. which is a C data structure not	112	Every C<aio_*> function creates a request. which is a C data structure not
137	directly visible to Perl.	113	directly visible to Perl.
…		…
187		163
188	package IO::AIO;	164	package IO::AIO;
189		165
190	use Carp ();	166	use Carp ();
191		167
192	no warnings;	168	use common::sense;
193	use strict 'vars';
194		169
195	use base 'Exporter';	170	use base 'Exporter';
196		171
197	BEGIN {	172	BEGIN {
198	our $VERSION = '3.1';	173	our $VERSION = '4.15';
199		174
200	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	175	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
201	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
		178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
203	aio_fdatasync aio_pathsync aio_readahead	179	aio_pathsync aio_readahead aio_fiemap
204	aio_rename aio_link aio_move aio_copy aio_group	180	aio_rename aio_link aio_move aio_copy aio_group
205	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206	aio_chmod aio_utime aio_truncate);	182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
		184	aio_statvfs
		185	aio_wd);
207		186
208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210	min_parallel max_parallel max_idle	189	min_parallel max_parallel max_idle idle_timeout
211	nreqs nready npending nthreads	190	nreqs nready npending nthreads
212	max_poll_time max_poll_reqs);	191	max_poll_time max_poll_reqs
		192	sendfile fadvise madvise
		193	mmap munmap munlock munlockall);
		194
		195	push @AIO_REQ, qw(aio_busy); # not exported
213		196
214	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
215		198
216	require XSLoader;	199	require XSLoader;
217	XSLoader::load ("IO::AIO", $VERSION);	200	XSLoader::load ("IO::AIO", $VERSION);
218	}	201	}
219		202
220	=head1 FUNCTIONS	203	=head1 FUNCTIONS
221		204
222	=head2 AIO REQUEST FUNCTIONS	205	=head2 QUICK OVERVIEW
		206
		207	This section simply lists the prototypes of the most important functions
		208	for quick reference. See the following sections for function-by-function
		209	documentation.
		210
		211	aio_wd $pathname, $callback->($wd)
		212	aio_open $pathname, $flags, $mode, $callback->($fh)
		213	aio_close $fh, $callback->($status)
		214	aio_seek $fh,$offset,$whence, $callback->($offs)
		215	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		217	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		218	aio_readahead $fh,$offset,$length, $callback->($retval)
		219	aio_stat $fh_or_path, $callback->($status)
		220	aio_lstat $fh, $callback->($status)
		221	aio_statvfs $fh_or_path, $callback->($statvfs)
		222	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		223	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		224	aio_chmod $fh_or_path, $mode, $callback->($status)
		225	aio_truncate $fh_or_path, $offset, $callback->($status)
		226	aio_unlink $pathname, $callback->($status)
		227	aio_mknod $pathname, $mode, $dev, $callback->($status)
		228	aio_link $srcpath, $dstpath, $callback->($status)
		229	aio_symlink $srcpath, $dstpath, $callback->($status)
		230	aio_readlink $pathname, $callback->($link)
		231	aio_realpath $pathname, $callback->($link)
		232	aio_rename $srcpath, $dstpath, $callback->($status)
		233	aio_mkdir $pathname, $mode, $callback->($status)
		234	aio_rmdir $pathname, $callback->($status)
		235	aio_readdir $pathname, $callback->($entries)
		236	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		237	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		238	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		239	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		240	aio_load $pathname, $data, $callback->($status)
		241	aio_copy $srcpath, $dstpath, $callback->($status)
		242	aio_move $srcpath, $dstpath, $callback->($status)
		243	aio_rmtree $pathname, $callback->($status)
		244	aio_sync $callback->($status)
		245	aio_syncfs $fh, $callback->($status)
		246	aio_fsync $fh, $callback->($status)
		247	aio_fdatasync $fh, $callback->($status)
		248	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		249	aio_pathsync $pathname, $callback->($status)
		250	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		251	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		252	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		253	aio_mlockall $flags, $callback->($status)
		254	aio_group $callback->(...)
		255	aio_nop $callback->()
		256
		257	$prev_pri = aioreq_pri [$pri]
		258	aioreq_nice $pri_adjust
		259
		260	IO::AIO::poll_wait
		261	IO::AIO::poll_cb
		262	IO::AIO::poll
		263	IO::AIO::flush
		264	IO::AIO::max_poll_reqs $nreqs
		265	IO::AIO::max_poll_time $seconds
		266	IO::AIO::min_parallel $nthreads
		267	IO::AIO::max_parallel $nthreads
		268	IO::AIO::max_idle $nthreads
		269	IO::AIO::idle_timeout $seconds
		270	IO::AIO::max_outstanding $maxreqs
		271	IO::AIO::nreqs
		272	IO::AIO::nready
		273	IO::AIO::npending
		274
		275	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		276	IO::AIO::fadvise $fh, $offset, $len, $advice
		277	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		278	IO::AIO::munmap $scalar
		279	IO::AIO::madvise $scalar, $offset, $length, $advice
		280	IO::AIO::mprotect $scalar, $offset, $length, $protect
		281	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		282	IO::AIO::munlockall
		283
		284	=head2 API NOTES
223		285
224	All the C<aio_*> calls are more or less thin wrappers around the syscall	286	All the C<aio_*> calls are more or less thin wrappers around the syscall
225	with the same name (sans C<aio_>). The arguments are similar or identical,	287	with the same name (sans C<aio_>). The arguments are similar or identical,
226	and they all accept an additional (and optional) C<$callback> argument	288	and they all accept an additional (and optional) C<$callback> argument
227	which must be a code reference. This code reference will get called with	289	which must be a code reference. This code reference will be called after
228	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	290	the syscall has been executed in an asynchronous fashion. The results
229	perl, which usually delivers "false") as its sole argument after the given	291	of the request will be passed as arguments to the callback (and, if an
230	syscall has been executed asynchronously.	292	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		293	most syscalls return C<-1> on error, unlike perl, which usually delivers
		294	"false").
		295
		296	Some requests (such as C<aio_readdir>) pass the actual results and
		297	communicate failures by passing C<undef>.
231		298
232	All functions expecting a filehandle keep a copy of the filehandle	299	All functions expecting a filehandle keep a copy of the filehandle
233	internally until the request has finished.	300	internally until the request has finished.
234		301
235	All functions return request objects of type L<IO::AIO::REQ> that allow	302	All functions return request objects of type L<IO::AIO::REQ> that allow
236	further manipulation of those requests while they are in-flight.	303	further manipulation of those requests while they are in-flight.
237		304
238	The pathnames you pass to these routines I<must> be absolute and	305	The pathnames you pass to these routines I<should> be absolute. The
239	encoded as octets. The reason for the former is that at the time the	306	reason for this is that at the time the request is being executed, the
240	request is being executed, the current working directory could have	307	current working directory could have changed. Alternatively, you can
241	changed. Alternatively, you can make sure that you never change the	308	make sure that you never change the current working directory anywhere
242	current working directory anywhere in the program and then use relative	309	in the program and then use relative paths. You can also take advantage
243	paths.	310	of IO::AIOs working directory abstraction, that lets you specify paths
		311	relative to some previously-opened "working directory object" - see the
		312	description of the C<IO::AIO::WD> class later in this document.
244		313
245	To encode pathnames as octets, either make sure you either: a) always pass	314	To encode pathnames as octets, either make sure you either: a) always pass
246	in filenames you got from outside (command line, readdir etc.) without	315	in filenames you got from outside (command line, readdir etc.) without
247	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	316	tinkering, b) are in your native filesystem encoding, c) use the Encode
248	your pathnames to the locale (or other) encoding in effect in the user	317	module and encode your pathnames to the locale (or other) encoding in
249	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	318	effect in the user environment, d) use Glib::filename_from_unicode on
250	use something else to ensure your scalar has the correct contents.	319	unicode filenames or e) use something else to ensure your scalar has the
		320	correct contents.
251		321
252	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	322	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
253	handles correctly whether it is set or not.	323	handles correctly whether it is set or not.
		324
		325	=head2 AIO REQUEST FUNCTIONS
254		326
255	=over 4	327	=over 4
256		328
257	=item $prev_pri = aioreq_pri [$pri]	329	=item $prev_pri = aioreq_pri [$pri]
258		330
…		…
305	by the umask in effect then the request is being executed, so better never	377	by the umask in effect then the request is being executed, so better never
306	change the umask.	378	change the umask.
307		379
308	Example:	380	Example:
309		381
310	aio_open "/etc/passwd", O_RDONLY, 0, sub {	382	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
311	if ($_[0]) {	383	if ($_[0]) {
312	print "open successful, fh is $_[0]\n";	384	print "open successful, fh is $_[0]\n";
313	...	385	...
314	} else {	386	} else {
315	die "open failed: $!\n";	387	die "open failed: $!\n";
316	}	388	}
317	};	389	};
318		390
		391	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		392	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		393	following POSIX and non-POSIX constants are available (missing ones on
		394	your system are, as usual, C<0>):
		395
		396	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		397	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		398	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		399
319		400
320	=item aio_close $fh, $callback->($status)	401	=item aio_close $fh, $callback->($status)
321		402
322	Asynchronously close a file and call the callback with the result	403	Asynchronously close a file and call the callback with the result
323	code.	404	code.
…		…
332	Or in other words: the file descriptor will be closed, but it will not be	413	Or in other words: the file descriptor will be closed, but it will not be
333	free for reuse until the perl filehandle is closed.	414	free for reuse until the perl filehandle is closed.
334		415
335	=cut	416	=cut
336		417
		418	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		419
		420	Seeks the filehandle to the new C<$offset>, similarly to perl's
		421	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		422	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		423	C<IO::AIO::SEEK_END>).
		424
		425	The resulting absolute offset will be passed to the callback, or C<-1> in
		426	case of an error.
		427
		428	In theory, the C<$whence> constants could be different than the
		429	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		430	so don't panic.
		431
		432	As a GNU/Linux (and maybe Solaris) extension, also the constants
		433	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		434	could be found. No guarantees about suitability for use in C<aio_seek> or
		435	Perl's C<sysseek> can be made though, although I would naively assume they
		436	"just work".
		437
337	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	438	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
338		439
339	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	440	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		441
341	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>	442	Reads or writes C<$length> bytes from or to the specified C<$fh> and
342	into the scalar given by C<$data> and offset C<$dataoffset> and calls the	443	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
343	callback without the actual number of bytes read (or -1 on error, just	444	and calls the callback without the actual number of bytes read (or -1 on
344	like the syscall).	445	error, just like the syscall).
		446
		447	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		448	offset plus the actual number of bytes read.
345		449
346	If C<$offset> is undefined, then the current file descriptor offset will	450	If C<$offset> is undefined, then the current file descriptor offset will
347	be used (and updated), otherwise the file descriptor offset will not be	451	be used (and updated), otherwise the file descriptor offset will not be
348	changed by these calls.	452	changed by these calls.
349		453
350	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.	454	If C<$length> is undefined in C<aio_write>, use the remaining length of
		455	C<$data>.
351		456
352	If C<$dataoffset> is less than zero, it will be counted from the end of	457	If C<$dataoffset> is less than zero, it will be counted from the end of
353	C<$data>.	458	C<$data>.
354		459
355	The C<$data> scalar I<MUST NOT> be modified in any way while the request	460	The C<$data> scalar I<MUST NOT> be modified in any way while the request
…		…
369		474
370	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	475	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
371	reading at byte offset C<$in_offset>, and starts writing at the current	476	reading at byte offset C<$in_offset>, and starts writing at the current
372	file offset of C<$out_fh>. Because of that, it is not safe to issue more	477	file offset of C<$out_fh>. Because of that, it is not safe to issue more
373	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	478	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
374	other.	479	other. The same C<$in_fh> works fine though, as this function does not
		480	move or use the file offset of C<$in_fh>.
375		481
		482	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		483	are written, and there is no way to find out how many more bytes have been
		484	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		485	number of bytes written to C<$out_fh>. Only if the result value equals
		486	C<$length> one can assume that C<$length> bytes have been read.
		487
		488	Unlike with other C<aio_> functions, it makes a lot of sense to use
		489	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		490	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		491	the socket I/O will be non-blocking. Note, however, that you can run
		492	into a trap where C<aio_sendfile> reads some data with readahead, then
		493	fails to write all data, and when the socket is ready the next time, the
		494	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		495	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		496	resource usage.
		497
376	This call tries to make use of a native C<sendfile> syscall to provide	498	This call tries to make use of a native C<sendfile>-like syscall to
377	zero-copy operation. For this to work, C<$out_fh> should refer to a	499	provide zero-copy operation. For this to work, C<$out_fh> should refer to
378	socket, and C<$in_fh> should refer to mmap'able file.	500	a socket, and C<$in_fh> should refer to an mmap'able file.
379		501
380	If the native sendfile call fails or is not implemented, it will be	502	If a native sendfile cannot be found or it fails with C<ENOSYS>,
381	emulated, so you can call C<aio_sendfile> on any type of filehandle	503	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		504	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
382	regardless of the limitations of the operating system.	505	type of filehandle regardless of the limitations of the operating system.
383		506
384	Please note, however, that C<aio_sendfile> can read more bytes from	507	As native sendfile syscalls (as practically any non-POSIX interface hacked
385	C<$in_fh> than are written, and there is no way to find out how many	508	together in a hurry to improve benchmark numbers) tend to be rather buggy
386	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	509	on many systems, this implementation tries to work around some known bugs
387	provides the number of bytes written to C<$out_fh>. Only if the result	510	in Linux and FreeBSD kernels (probably others, too), but that might fail,
388	value equals C<$length> one can assume that C<$length> bytes have been	511	so you really really should check the return value of C<aio_sendfile> -
389	read.	512	fewre bytes than expected might have been transferred.
390		513
391		514
392	=item aio_readahead $fh,$offset,$length, $callback->($retval)	515	=item aio_readahead $fh,$offset,$length, $callback->($retval)
393		516
394	C<aio_readahead> populates the page cache with data from a file so that	517	C<aio_readahead> populates the page cache with data from a file so that
…		…
417		540
418	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	541	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
419	error when stat'ing a large file, the results will be silently truncated	542	error when stat'ing a large file, the results will be silently truncated
420	unless perl itself is compiled with large file support.	543	unless perl itself is compiled with large file support.
421		544
		545	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		546	following constants and functions (if not implemented, the constants will
		547	be C<0> and the functions will either C<croak> or fall back on traditional
		548	behaviour).
		549
		550	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		551	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		552	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		553
422	Example: Print the length of F</etc/passwd>:	554	Example: Print the length of F</etc/passwd>:
423		555
424	aio_stat "/etc/passwd", sub {	556	aio_stat "/etc/passwd", sub {
425	$_[0] and die "stat failed: $!";	557	$_[0] and die "stat failed: $!";
426	print "size is ", -s _, "\n";	558	print "size is ", -s _, "\n";
427	};	559	};
428		560
429		561
		562	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		563
		564	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		565	whether a file handle or path was passed.
		566
		567	On success, the callback is passed a hash reference with the following
		568	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		569	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		570	is passed.
		571
		572	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		573	C<ST_NOSUID>.
		574
		575	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		576	their correct value when available, or to C<0> on systems that do
		577	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		578	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		579	C<ST_NODIRATIME> and C<ST_RELATIME>.
		580
		581	Example: stat C</wd> and dump out the data if successful.
		582
		583	aio_statvfs "/wd", sub {
		584	my $f = $_[0]
		585	or die "statvfs: $!";
		586
		587	use Data::Dumper;
		588	say Dumper $f;
		589	};
		590
		591	# result:
		592	{
		593	bsize => 1024,
		594	bfree => 4333064312,
		595	blocks => 10253828096,
		596	files => 2050765568,
		597	flag => 4096,
		598	favail => 2042092649,
		599	bavail => 4333064312,
		600	ffree => 2042092649,
		601	namemax => 255,
		602	frsize => 1024,
		603	fsid => 1810
		604	}
		605
		606
430	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	607	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
431		608
432	Works like perl's C<utime> function (including the special case of $atime	609	Works like perl's C<utime> function (including the special case of $atime
433	and $mtime being undef). Fractional times are supported if the underlying	610	and $mtime being undef). Fractional times are supported if the underlying
434	syscalls support them.	611	syscalls support them.
…		…
472		649
473	Asynchronously unlink (delete) a file and call the callback with the	650	Asynchronously unlink (delete) a file and call the callback with the
474	result code.	651	result code.
475		652
476		653
477	=item aio_mknod $path, $mode, $dev, $callback->($status)	654	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
478		655
479	[EXPERIMENTAL]	656	[EXPERIMENTAL]
480		657
481	Asynchronously create a device node (or fifo). See mknod(2).	658	Asynchronously create a device node (or fifo). See mknod(2).
482		659
483	The only (POSIX-) portable way of calling this function is:	660	The only (POSIX-) portable way of calling this function is:
484		661
485	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	662	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
486		663
		664	See C<aio_stat> for info about some potentially helpful extra constants
		665	and functions.
487		666
488	=item aio_link $srcpath, $dstpath, $callback->($status)	667	=item aio_link $srcpath, $dstpath, $callback->($status)
489		668
490	Asynchronously create a new link to the existing object at C<$srcpath> at	669	Asynchronously create a new link to the existing object at C<$srcpath> at
491	the path C<$dstpath> and call the callback with the result code.	670	the path C<$dstpath> and call the callback with the result code.
…		…
495		674
496	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	675	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
497	the path C<$dstpath> and call the callback with the result code.	676	the path C<$dstpath> and call the callback with the result code.
498		677
499		678
500	=item aio_readlink $path, $callback->($link)	679	=item aio_readlink $pathname, $callback->($link)
501		680
502	Asynchronously read the symlink specified by C<$path> and pass it to	681	Asynchronously read the symlink specified by C<$path> and pass it to
503	the callback. If an error occurs, nothing or undef gets passed to the	682	the callback. If an error occurs, nothing or undef gets passed to the
504	callback.	683	callback.
505		684
506		685
		686	=item aio_realpath $pathname, $callback->($path)
		687
		688	Asynchronously make the path absolute and resolve any symlinks in
		689	C<$path>. The resulting path only consists of directories (Same as
		690	L<Cwd::realpath>).
		691
		692	This request can be used to get the absolute path of the current working
		693	directory by passing it a path of F<.> (a single dot).
		694
		695
507	=item aio_rename $srcpath, $dstpath, $callback->($status)	696	=item aio_rename $srcpath, $dstpath, $callback->($status)
508		697
509	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	698	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
510	rename(2) and call the callback with the result code.	699	rename(2) and call the callback with the result code.
511		700
…		…
527		716
528	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	717	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
529	directory (i.e. opendir + readdir + closedir). The entries will not be	718	directory (i.e. opendir + readdir + closedir). The entries will not be
530	sorted, and will B<NOT> include the C<.> and C<..> entries.	719	sorted, and will B<NOT> include the C<.> and C<..> entries.
531		720
532	The callback a single argument which is either C<undef> or an array-ref	721	The callback is passed a single argument which is either C<undef> or an
533	with the filenames.	722	array-ref with the filenames.
534		723
535		724
		725	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		726
		727	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		728	tune behaviour and output format. In case of an error, C<$entries> will be
		729	C<undef>.
		730
		731	The flags are a combination of the following constants, ORed together (the
		732	flags will also be passed to the callback, possibly modified):
		733
		734	=over 4
		735
		736	=item IO::AIO::READDIR_DENTS
		737
		738	When this flag is off, then the callback gets an arrayref consisting of
		739	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		740	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		741	entry in more detail.
		742
		743	C<$name> is the name of the entry.
		744
		745	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		746
		747	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		748	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		749	C<IO::AIO::DT_WHT>.
		750
		751	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		752	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		753	scalars are read-only: you can not modify them.
		754
		755	C<$inode> is the inode number (which might not be exact on systems with 64
		756	bit inode numbers and 32 bit perls). This field has unspecified content on
		757	systems that do not deliver the inode information.
		758
		759	=item IO::AIO::READDIR_DIRS_FIRST
		760
		761	When this flag is set, then the names will be returned in an order where
		762	likely directories come first, in optimal stat order. This is useful when
		763	you need to quickly find directories, or you want to find all directories
		764	while avoiding to stat() each entry.
		765
		766	If the system returns type information in readdir, then this is used
		767	to find directories directly. Otherwise, likely directories are names
		768	beginning with ".", or otherwise names with no dots, of which names with
		769	short names are tried first.
		770
		771	=item IO::AIO::READDIR_STAT_ORDER
		772
		773	When this flag is set, then the names will be returned in an order
		774	suitable for stat()'ing each one. That is, when you plan to stat()
		775	all files in the given directory, then the returned order will likely
		776	be fastest.
		777
		778	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		779	the likely dirs come first, resulting in a less optimal stat order.
		780
		781	=item IO::AIO::READDIR_FOUND_UNKNOWN
		782
		783	This flag should not be set when calling C<aio_readdirx>. Instead, it
		784	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		785	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		786	C<$type>'s are known, which can be used to speed up some algorithms.
		787
		788	=back
		789
		790
536	=item aio_load $path, $data, $callback->($status)	791	=item aio_load $pathname, $data, $callback->($status)
537		792
538	This is a composite request that tries to fully load the given file into	793	This is a composite request that tries to fully load the given file into
539	memory. Status is the same as with aio_read.	794	memory. Status is the same as with aio_read.
540		795
541	=cut	796	=cut
…		…
563		818
564	=item aio_copy $srcpath, $dstpath, $callback->($status)	819	=item aio_copy $srcpath, $dstpath, $callback->($status)
565		820
566	Try to copy the I<file> (directories not supported as either source or	821	Try to copy the I<file> (directories not supported as either source or
567	destination) from C<$srcpath> to C<$dstpath> and call the callback with	822	destination) from C<$srcpath> to C<$dstpath> and call the callback with
568	the C<0> (error) or C<-1> ok.	823	a status of C<0> (ok) or C<-1> (error, see C<$!>).
569		824
570	This is a composite request that creates the destination file with	825	This is a composite request that creates the destination file with
571	mode 0200 and copies the contents of the source file into it using	826	mode 0200 and copies the contents of the source file into it using
572	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	827	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
573	uid/gid, in that order.	828	uid/gid, in that order.
…		…
585	my $grp = aio_group $cb;	840	my $grp = aio_group $cb;
586		841
587	aioreq_pri $pri;	842	aioreq_pri $pri;
588	add $grp aio_open $src, O_RDONLY, 0, sub {	843	add $grp aio_open $src, O_RDONLY, 0, sub {
589	if (my $src_fh = $_[0]) {	844	if (my $src_fh = $_[0]) {
590	my @stat = stat $src_fh;	845	my @stat = stat $src_fh; # hmm, might block over nfs?
591		846
592	aioreq_pri $pri;	847	aioreq_pri $pri;
593	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	848	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
594	if (my $dst_fh = $_[0]) {	849	if (my $dst_fh = $_[0]) {
595	aioreq_pri $pri;	850	aioreq_pri $pri;
596	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	851	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
597	if ($_[0] == $stat[7]) {	852	if ($_[0] == $stat[7]) {
598	$grp->result (0);	853	$grp->result (0);
599	close $src_fh;	854	close $src_fh;
600		855
601	# those should not normally block. should. should.	856	my $ch = sub {
602	utime $stat[8], $stat[9], $dst;	857	aioreq_pri $pri;
603	chmod $stat[2] & 07777, $dst_fh;	858	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
604	chown $stat[4], $stat[5], $dst_fh;	859	aioreq_pri $pri;
		860	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		861	aioreq_pri $pri;
		862	add $grp aio_close $dst_fh;
		863	}
		864	};
		865	};
605		866
606	aioreq_pri $pri;	867	aioreq_pri $pri;
607	add $grp aio_close $dst_fh;	868	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		869	if ($_[0] < 0 && $! == ENOSYS) {
		870	aioreq_pri $pri;
		871	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		872	} else {
		873	$ch->();
		874	}
		875	};
608	} else {	876	} else {
609	$grp->result (-1);	877	$grp->result (-1);
610	close $src_fh;	878	close $src_fh;
611	close $dst_fh;	879	close $dst_fh;
612		880
…		…
629		897
630	=item aio_move $srcpath, $dstpath, $callback->($status)	898	=item aio_move $srcpath, $dstpath, $callback->($status)
631		899
632	Try to move the I<file> (directories not supported as either source or	900	Try to move the I<file> (directories not supported as either source or
633	destination) from C<$srcpath> to C<$dstpath> and call the callback with	901	destination) from C<$srcpath> to C<$dstpath> and call the callback with
634	the C<0> (error) or C<-1> ok.	902	a status of C<0> (ok) or C<-1> (error, see C<$!>).
635		903
636	This is a composite request that tries to rename(2) the file first. If	904	This is a composite request that tries to rename(2) the file first; if
637	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	905	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
638	that is successful, unlinking the C<$srcpath>.	906	that is successful, unlinks the C<$srcpath>.
639		907
640	=cut	908	=cut
641		909
642	sub aio_move($$;$) {	910	sub aio_move($$;$) {
643	my ($src, $dst, $cb) = @_;	911	my ($src, $dst, $cb) = @_;
…		…
650	if ($_[0] && $! == EXDEV) {	918	if ($_[0] && $! == EXDEV) {
651	aioreq_pri $pri;	919	aioreq_pri $pri;
652	add $grp aio_copy $src, $dst, sub {	920	add $grp aio_copy $src, $dst, sub {
653	$grp->result ($_[0]);	921	$grp->result ($_[0]);
654		922
655	if (!$_[0]) {	923	unless ($_[0]) {
656	aioreq_pri $pri;	924	aioreq_pri $pri;
657	add $grp aio_unlink $src;	925	add $grp aio_unlink $src;
658	}	926	}
659	};	927	};
660	} else {	928	} else {
…		…
663	};	931	};
664		932
665	$grp	933	$grp
666	}	934	}
667		935
668	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	936	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
669		937
670	Scans a directory (similar to C<aio_readdir>) but additionally tries to	938	Scans a directory (similar to C<aio_readdir>) but additionally tries to
671	efficiently separate the entries of directory C<$path> into two sets of	939	efficiently separate the entries of directory C<$path> into two sets of
672	names, directories you can recurse into (directories), and ones you cannot	940	names, directories you can recurse into (directories), and ones you cannot
673	recurse into (everything else, including symlinks to directories).	941	recurse into (everything else, including symlinks to directories).
…		…
690		958
691	Implementation notes.	959	Implementation notes.
692		960
693	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	961	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
694		962
		963	If readdir returns file type information, then this is used directly to
		964	find directories.
		965
695	After reading the directory, the modification time, size etc. of the	966	Otherwise, after reading the directory, the modification time, size etc.
696	directory before and after the readdir is checked, and if they match (and	967	of the directory before and after the readdir is checked, and if they
697	isn't the current time), the link count will be used to decide how many	968	match (and isn't the current time), the link count will be used to decide
698	entries are directories (if >= 2). Otherwise, no knowledge of the number	969	how many entries are directories (if >= 2). Otherwise, no knowledge of the
699	of subdirectories will be assumed.	970	number of subdirectories will be assumed.
700		971
701	Then entries will be sorted into likely directories (everything without	972	Then entries will be sorted into likely directories a non-initial dot
702	a non-initial dot currently) and likely non-directories (everything	973	currently) and likely non-directories (see C<aio_readdirx>). Then every
703	else). Then every entry plus an appended C</.> will be C<stat>'ed,	974	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
704	likely directories first. If that succeeds, it assumes that the entry	975	in order of their inode numbers. If that succeeds, it assumes that the
705	is a directory or a symlink to directory (which will be checked	976	entry is a directory or a symlink to directory (which will be checked
706	seperately). This is often faster than stat'ing the entry itself because	977	separately). This is often faster than stat'ing the entry itself because
707	filesystems might detect the type of the entry without reading the inode	978	filesystems might detect the type of the entry without reading the inode
708	data (e.g. ext2fs filetype feature).	979	data (e.g. ext2fs filetype feature), even on systems that cannot return
		980	the filetype information on readdir.
709		981
710	If the known number of directories (link count - 2) has been reached, the	982	If the known number of directories (link count - 2) has been reached, the
711	rest of the entries is assumed to be non-directories.	983	rest of the entries is assumed to be non-directories.
712		984
713	This only works with certainty on POSIX (= UNIX) filesystems, which	985	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
726		998
727	my $grp = aio_group $cb;	999	my $grp = aio_group $cb;
728		1000
729	$maxreq = 4 if $maxreq <= 0;	1001	$maxreq = 4 if $maxreq <= 0;
730		1002
731	# stat once	1003	# get a wd object
732	aioreq_pri $pri;	1004	aioreq_pri $pri;
733	add $grp aio_stat $path, sub {	1005	add $grp aio_wd $path, sub {
		1006	$_[0]
734	return $grp->result () if $_[0];	1007	or return $grp->result ();
735	my $now = time;
736	my $hash1 = join ":", (stat _)[0,1,3,7,9];
737		1008
738	# read the directory entries	1009	my $wd = [shift, "."];
		1010
		1011	# stat once
739	aioreq_pri $pri;	1012	aioreq_pri $pri;
740	add $grp aio_readdir $path, sub {	1013	add $grp aio_stat $wd, sub {
741	my $entries = shift
742	or return $grp->result ();	1014	return $grp->result () if $_[0];
		1015	my $now = time;
		1016	my $hash1 = join ":", (stat _)[0,1,3,7,9];
743		1017
744	# stat the dir another time	1018	# read the directory entries
745	aioreq_pri $pri;	1019	aioreq_pri $pri;
		1020	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1021	my $entries = shift
		1022	or return $grp->result ();
		1023
		1024	# stat the dir another time
		1025	aioreq_pri $pri;
746	add $grp aio_stat $path, sub {	1026	add $grp aio_stat $wd, sub {
747	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1027	my $hash2 = join ":", (stat _)[0,1,3,7,9];
748		1028
749	my $ndirs;	1029	my $ndirs;
750		1030
751	# take the slow route if anything looks fishy	1031	# take the slow route if anything looks fishy
752	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1032	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
753	$ndirs = -1;	1033	$ndirs = -1;
754	} else {	1034	} else {
755	# if nlink == 2, we are finished	1035	# if nlink == 2, we are finished
756	# on non-posix-fs's, we rely on nlink < 2	1036	# for non-posix-fs's, we rely on nlink < 2
757	$ndirs = (stat _)[3] - 2	1037	$ndirs = (stat _)[3] - 2
758	or return $grp->result ([], $entries);	1038	or return $grp->result ([], $entries);
759	}	1039	}
760		1040
761	# sort into likely dirs and likely nondirs
762	# dirs == files without ".", short entries first
763	$entries = [map $_->[0],
764	sort { $b->[1] cmp $a->[1] }
765	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
766	@$entries];
767
768	my (@dirs, @nondirs);	1041	my (@dirs, @nondirs);
769		1042
770	my $statgrp = add $grp aio_group sub {	1043	my $statgrp = add $grp aio_group sub {
771	$grp->result (\@dirs, \@nondirs);	1044	$grp->result (\@dirs, \@nondirs);
772	};	1045	};
773		1046
774	limit $statgrp $maxreq;	1047	limit $statgrp $maxreq;
775	feed $statgrp sub {	1048	feed $statgrp sub {
776	return unless @$entries;	1049	return unless @$entries;
777	my $entry = pop @$entries;	1050	my $entry = shift @$entries;
778		1051
779	aioreq_pri $pri;	1052	aioreq_pri $pri;
		1053	$wd->[1] = "$entry/.";
780	add $statgrp aio_stat "$path/$entry/.", sub {	1054	add $statgrp aio_stat $wd, sub {
781	if ($_[0] < 0) {	1055	if ($_[0] < 0) {
782	push @nondirs, $entry;	1056	push @nondirs, $entry;
783	} else {	1057	} else {
784	# need to check for real directory	1058	# need to check for real directory
785	aioreq_pri $pri;	1059	aioreq_pri $pri;
		1060	$wd->[1] = $entry;
786	add $statgrp aio_lstat "$path/$entry", sub {	1061	add $statgrp aio_lstat $wd, sub {
787	if (-d _) {	1062	if (-d _) {
788	push @dirs, $entry;	1063	push @dirs, $entry;
789		1064
790	unless (--$ndirs) {	1065	unless (--$ndirs) {
791	push @nondirs, @$entries;	1066	push @nondirs, @$entries;
792	feed $statgrp;	1067	feed $statgrp;
		1068	}
		1069	} else {
		1070	push @nondirs, $entry;
793	}	1071	}
794	} else {
795	push @nondirs, $entry;
796	}	1072	}
797	}	1073	}
798	}	1074	};
799	};	1075	};
800	};	1076	};
801	};	1077	};
802	};	1078	};
803	};	1079	};
804		1080
805	$grp	1081	$grp
806	}	1082	}
807		1083
808	=item aio_rmtree $path, $callback->($status)	1084	=item aio_rmtree $pathname, $callback->($status)
809		1085
810	Delete a directory tree starting (and including) C<$path>, return the	1086	Delete a directory tree starting (and including) C<$path>, return the
811	status of the final C<rmdir> only. This is a composite request that	1087	status of the final C<rmdir> only. This is a composite request that
812	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1088	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
813	everything else.	1089	everything else.
…		…
855	callback with the fdatasync result code.	1131	callback with the fdatasync result code.
856		1132
857	If this call isn't available because your OS lacks it or it couldn't be	1133	If this call isn't available because your OS lacks it or it couldn't be
858	detected, it will be emulated by calling C<fsync> instead.	1134	detected, it will be emulated by calling C<fsync> instead.
859		1135
		1136	=item aio_syncfs $fh, $callback->($status)
		1137
		1138	Asynchronously call the syncfs syscall to sync the filesystem associated
		1139	to the given filehandle and call the callback with the syncfs result
		1140	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1141	errno to C<ENOSYS> nevertheless.
		1142
		1143	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1144
		1145	Sync the data portion of the file specified by C<$offset> and C<$length>
		1146	to disk (but NOT the metadata), by calling the Linux-specific
		1147	sync_file_range call. If sync_file_range is not available or it returns
		1148	ENOSYS, then fdatasync or fsync is being substituted.
		1149
		1150	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1151	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1152	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1153	manpage for details.
		1154
860	=item aio_pathsync $path, $callback->($status)	1155	=item aio_pathsync $pathname, $callback->($status)
861		1156
862	This request tries to open, fsync and close the given path. This is a	1157	This request tries to open, fsync and close the given path. This is a
863	composite request intended to sync directories after directory operations	1158	composite request intended to sync directories after directory operations
864	(E.g. rename). This might not work on all operating systems or have any	1159	(E.g. rename). This might not work on all operating systems or have any
865	specific effect, but usually it makes sure that directory changes get	1160	specific effect, but usually it makes sure that directory changes get
866	written to disc. It works for anything that can be opened for read-only,	1161	written to disc. It works for anything that can be opened for read-only,
867	not just directories.	1162	not just directories.
		1163
		1164	Future versions of this function might fall back to other methods when
		1165	C<fsync> on the directory fails (such as calling C<sync>).
868		1166
869	Passes C<0> when everything went ok, and C<-1> on error.	1167	Passes C<0> when everything went ok, and C<-1> on error.
870		1168
871	=cut	1169	=cut
872		1170
…		…
893	};	1191	};
894		1192
895	$grp	1193	$grp
896	}	1194	}
897		1195
		1196	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1197
		1198	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1199	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1200	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1201	scalar must only be modified in-place while an aio operation is pending on
		1202	it).
		1203
		1204	It calls the C<msync> function of your OS, if available, with the memory
		1205	area starting at C<$offset> in the string and ending C<$length> bytes
		1206	later. If C<$length> is negative, counts from the end, and if C<$length>
		1207	is C<undef>, then it goes till the end of the string. The flags can be
		1208	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1209	C<IO::AIO::MS_SYNC>.
		1210
		1211	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1212
		1213	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1214	scalars.
		1215
		1216	It touches (reads or writes) all memory pages in the specified
		1217	range inside the scalar. All caveats and parameters are the same
		1218	as for C<aio_msync>, above, except for flags, which must be either
		1219	C<0> (which reads all pages and ensures they are instantiated) or
		1220	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1221	writing an octet from it, which dirties the page).
		1222
		1223	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1224
		1225	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1226	scalars.
		1227
		1228	It reads in all the pages of the underlying storage into memory (if any)
		1229	and locks them, so they are not getting swapped/paged out or removed.
		1230
		1231	If C<$length> is undefined, then the scalar will be locked till the end.
		1232
		1233	On systems that do not implement C<mlock>, this function returns C<-1>
		1234	and sets errno to C<ENOSYS>.
		1235
		1236	Note that the corresponding C<munlock> is synchronous and is
		1237	documented under L<MISCELLANEOUS FUNCTIONS>.
		1238
		1239	Example: open a file, mmap and mlock it - both will be undone when
		1240	C<$data> gets destroyed.
		1241
		1242	open my $fh, "<", $path or die "$path: $!";
		1243	my $data;
		1244	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1245	aio_mlock $data; # mlock in background
		1246
		1247	=item aio_mlockall $flags, $callback->($status)
		1248
		1249	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1250	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1251
		1252	On systems that do not implement C<mlockall>, this function returns C<-1>
		1253	and sets errno to C<ENOSYS>.
		1254
		1255	Note that the corresponding C<munlockall> is synchronous and is
		1256	documented under L<MISCELLANEOUS FUNCTIONS>.
		1257
		1258	Example: asynchronously lock all current and future pages into memory.
		1259
		1260	aio_mlockall IO::AIO::MCL_FUTURE;
		1261
		1262	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1263
		1264	Queries the extents of the given file (by calling the Linux FIEMAP ioctl,
		1265	see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the
		1266	C<ioctl> is not available on your OS, then this rquiest will fail with
		1267	C<ENOSYS>.
		1268
		1269	C<$start> is the starting offset to query extents for, C<$length> is the
		1270	size of the range to query - if it is C<undef>, then the whole file will
		1271	be queried.
		1272
		1273	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1274	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1275	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1276	the data portion.
		1277
		1278	C<$count> is the maximum number of extent records to return. If it is
		1279	C<undef>, then IO::AIO queries all extents of the file. As a very special
		1280	case, if it is C<0>, then the callback receives the number of extents
		1281	instead of the extents themselves.
		1282
		1283	If an error occurs, the callback receives no arguments. The special
		1284	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1285
		1286	Otherwise, the callback receives an array reference with extent
		1287	structures. Each extent structure is an array reference itself, with the
		1288	following members:
		1289
		1290	[$logical, $physical, $length, $flags]
		1291
		1292	Flags is any combination of the following flag values (typically either C<0>
		1293	or C<IO::AIO::FIEMAP_EXTENT_LAST>):
		1294
		1295	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1296	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1297	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1298	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1299	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1300	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1301
898	=item aio_group $callback->(...)	1302	=item aio_group $callback->(...)
899		1303
900	This is a very special aio request: Instead of doing something, it is a	1304	This is a very special aio request: Instead of doing something, it is a
901	container for other aio requests, which is useful if you want to bundle	1305	container for other aio requests, which is useful if you want to bundle
902	many requests into a single, composite, request with a definite callback	1306	many requests into a single, composite, request with a definite callback
…		…
939	immense (it blocks a thread for a long time) so do not use this function	1343	immense (it blocks a thread for a long time) so do not use this function
940	except to put your application under artificial I/O pressure.	1344	except to put your application under artificial I/O pressure.
941		1345
942	=back	1346	=back
943		1347
		1348
		1349	=head2 IO::AIO::WD - multiple working directories
		1350
		1351	Your process only has one current working directory, which is used by all
		1352	threads. This makes it hard to use relative paths (some other component
		1353	could call C<chdir> at any time, and it is hard to control when the path
		1354	will be used by IO::AIO).
		1355
		1356	One solution for this is to always use absolute paths. This usually works,
		1357	but can be quite slow (the kernel has to walk the whole path on every
		1358	access), and can also be a hassle to implement.
		1359
		1360	Newer POSIX systems have a number of functions (openat, fdopendir,
		1361	futimensat and so on) that make it possible to specify working directories
		1362	per operation.
		1363
		1364	For portability, and because the clowns who "designed", or shall I write,
		1365	perpetrated this new interface were obviously half-drunk, this abstraction
		1366	cannot be perfect, though.
		1367
		1368	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1369	object. This object stores the canonicalised, absolute version of the
		1370	path, and on systems that allow it, also a directory file descriptor.
		1371
		1372	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1373	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1374	object and a pathname instead (or the IO::AIO::WD object alone, which
		1375	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1376	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1377	to that IO::AIO::WD object.
		1378
		1379	For example, to get a wd object for F</etc> and then stat F<passwd>
		1380	inside, you would write:
		1381
		1382	aio_wd "/etc", sub {
		1383	my $etcdir = shift;
		1384
		1385	# although $etcdir can be undef on error, there is generally no reason
		1386	# to check for errors here, as aio_stat will fail with ENOENT
		1387	# when $etcdir is undef.
		1388
		1389	aio_stat [$etcdir, "passwd"], sub {
		1390	# yay
		1391	};
		1392	};
		1393
		1394	That C<aio_wd> is a request and not a normal function shows that creating
		1395	an IO::AIO::WD object is itself a potentially blocking operation, which is
		1396	why it is done asynchronously.
		1397
		1398	To stat the directory obtained with C<aio_wd> above, one could write
		1399	either of the following three request calls:
		1400
		1401	aio_lstat "/etc" , sub { ... # pathname as normal string
		1402	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1403	aio_lstat $wd , sub { ... # shorthand for the previous
		1404
		1405	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1406	object and the pathname string, so you could write the following without
		1407	causing any issues due to C<$path> getting reused:
		1408
		1409	my $path = [$wd, undef];
		1410
		1411	for my $name (qw(abc def ghi)) {
		1412	$path->[1] = $name;
		1413	aio_stat $path, sub {
		1414	# ...
		1415	};
		1416	}
		1417
		1418	There are some caveats: when directories get renamed (or deleted), the
		1419	pathname string doesn't change, so will point to the new directory (or
		1420	nowhere at all), while the directory fd, if available on the system,
		1421	will still point to the original directory. Most functions accepting a
		1422	pathname will use the directory fd on newer systems, and the string on
		1423	older systems. Some functions (such as realpath) will always rely on the
		1424	string form of the pathname.
		1425
		1426	So this fucntionality is mainly useful to get some protection against
		1427	C<chdir>, to easily get an absolute path out of a relative path for future
		1428	reference, and to speed up doing many operations in the same directory
		1429	(e.g. when stat'ing all files in a directory).
		1430
		1431	The following functions implement this working directory abstraction:
		1432
		1433	=over 4
		1434
		1435	=item aio_wd $pathname, $callback->($wd)
		1436
		1437	Asynchonously canonicalise the given pathname and convert it to an
		1438	IO::AIO::WD object representing it. If possible and supported on the
		1439	system, also open a directory fd to speed up pathname resolution relative
		1440	to this working directory.
		1441
		1442	If something goes wrong, then C<undef> is passwd to the callback instead
		1443	of a working directory object and C<$!> is set appropriately. Since
		1444	passing C<undef> as working directory component of a pathname fails the
		1445	request with C<ENOENT>, there is often no need for error checking in the
		1446	C<aio_wd> callback, as future requests using the value will fail in the
		1447	expected way.
		1448
		1449	If this call isn't available because your OS lacks it or it couldn't be
		1450	detected, it will be emulated by calling C<fsync> instead.
		1451
		1452	=item IO::AIO::CWD
		1453
		1454	This is a compiletime constant (object) that represents the process
		1455	current working directory.
		1456
		1457	Specifying this object as working directory object for a pathname is as
		1458	if the pathname would be specified directly, without a directory object,
		1459	e.g., these calls are functionally identical:
		1460
		1461	aio_stat "somefile", sub { ... };
		1462	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1463
		1464	=back
		1465
		1466
944	=head2 IO::AIO::REQ CLASS	1467	=head2 IO::AIO::REQ CLASS
945		1468
946	All non-aggregate C<aio_*> functions return an object of this class when	1469	All non-aggregate C<aio_*> functions return an object of this class when
947	called in non-void context.	1470	called in non-void context.
948		1471
…		…
951	=item cancel $req	1474	=item cancel $req
952		1475
953	Cancels the request, if possible. Has the effect of skipping execution	1476	Cancels the request, if possible. Has the effect of skipping execution
954	when entering the B<execute> state and skipping calling the callback when	1477	when entering the B<execute> state and skipping calling the callback when
955	entering the the B<result> state, but will leave the request otherwise	1478	entering the the B<result> state, but will leave the request otherwise
956	untouched. That means that requests that currently execute will not be	1479	untouched (with the exception of readdir). That means that requests that
957	stopped and resources held by the request will not be freed prematurely.	1480	currently execute will not be stopped and resources held by the request
		1481	will not be freed prematurely.
958		1482
959	=item cb $req $callback->(...)	1483	=item cb $req $callback->(...)
960		1484
961	Replace (or simply set) the callback registered to the request.	1485	Replace (or simply set) the callback registered to the request.
962		1486
…		…
1036	=item $grp->cancel_subs	1560	=item $grp->cancel_subs
1037		1561
1038	Cancel all subrequests and clears any feeder, but not the group request	1562	Cancel all subrequests and clears any feeder, but not the group request
1039	itself. Useful when you queued a lot of events but got a result early.	1563	itself. Useful when you queued a lot of events but got a result early.
1040		1564
		1565	The group request will finish normally (you cannot add requests to the
		1566	group).
		1567
1041	=item $grp->result (...)	1568	=item $grp->result (...)
1042		1569
1043	Set the result value(s) that will be passed to the group callback when all	1570	Set the result value(s) that will be passed to the group callback when all
1044	subrequests have finished and set the groups errno to the current value	1571	subrequests have finished and set the groups errno to the current value
1045	of errno (just like calling C<errno> without an error number). By default,	1572	of errno (just like calling C<errno> without an error number). By default,
…		…
1060	=item feed $grp $callback->($grp)	1587	=item feed $grp $callback->($grp)
1061		1588
1062	Sets a feeder/generator on this group: every group can have an attached	1589	Sets a feeder/generator on this group: every group can have an attached
1063	generator that generates requests if idle. The idea behind this is that,	1590	generator that generates requests if idle. The idea behind this is that,
1064	although you could just queue as many requests as you want in a group,	1591	although you could just queue as many requests as you want in a group,
1065	this might starve other requests for a potentially long time. For	1592	this might starve other requests for a potentially long time. For example,
1066	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1593	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1067	requests, delaying any later requests for a long time.	1594	requests, delaying any later requests for a long time.
1068		1595
1069	To avoid this, and allow incremental generation of requests, you can	1596	To avoid this, and allow incremental generation of requests, you can
1070	instead a group and set a feeder on it that generates those requests. The	1597	instead a group and set a feeder on it that generates those requests. The
1071	feed callback will be called whenever there are few enough (see C<limit>,	1598	feed callback will be called whenever there are few enough (see C<limit>,
…		…
1076	not impose any limits).	1603	not impose any limits).
1077		1604
1078	If the feed does not queue more requests when called, it will be	1605	If the feed does not queue more requests when called, it will be
1079	automatically removed from the group.	1606	automatically removed from the group.
1080		1607
1081	If the feed limit is C<0>, it will be set to C<2> automatically.	1608	If the feed limit is C<0> when this method is called, it will be set to
		1609	C<2> automatically.
1082		1610
1083	Example:	1611	Example:
1084		1612
1085	# stat all files in @files, but only ever use four aio requests concurrently:	1613	# stat all files in @files, but only ever use four aio requests concurrently:
1086		1614
…		…
1098	Sets the feeder limit for the group: The feeder will be called whenever	1626	Sets the feeder limit for the group: The feeder will be called whenever
1099	the group contains less than this many requests.	1627	the group contains less than this many requests.
1100		1628
1101	Setting the limit to C<0> will pause the feeding process.	1629	Setting the limit to C<0> will pause the feeding process.
1102		1630
		1631	The default value for the limit is C<0>, but note that setting a feeder
		1632	automatically bumps it up to C<2>.
		1633
1103	=back	1634	=back
1104		1635
1105	=head2 SUPPORT FUNCTIONS	1636	=head2 SUPPORT FUNCTIONS
1106		1637
1107	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1638	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
1109	=over 4	1640	=over 4
1110		1641
1111	=item $fileno = IO::AIO::poll_fileno	1642	=item $fileno = IO::AIO::poll_fileno
1112		1643
1113	Return the I<request result pipe file descriptor>. This filehandle must be	1644	Return the I<request result pipe file descriptor>. This filehandle must be
1114	polled for reading by some mechanism outside this module (e.g. Event or	1645	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1115	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1646	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1116	to call C<poll_cb> to check the results.	1647	you have to call C<poll_cb> to check the results.
1117		1648
1118	See C<poll_cb> for an example.	1649	See C<poll_cb> for an example.
1119		1650
1120	=item IO::AIO::poll_cb	1651	=item IO::AIO::poll_cb
1121		1652
1122	Process some outstanding events on the result pipe. You have to call this	1653	Process some outstanding events on the result pipe. You have to call
1123	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1654	this regularly. Returns C<0> if all events could be processed (or there
1124	returned earlier for whatever reason. Returns immediately when no events	1655	were no events to process), or C<-1> if it returned earlier for whatever
1125	are outstanding. The amount of events processed depends on the settings of	1656	reason. Returns immediately when no events are outstanding. The amount of
1126	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1657	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1658	C<IO::AIO::max_poll_time>.
1127		1659
1128	If not all requests were processed for whatever reason, the filehandle	1660	If not all requests were processed for whatever reason, the filehandle
1129	will still be ready when C<poll_cb> returns, so normally you don't have to	1661	will still be ready when C<poll_cb> returns, so normally you don't have to
1130	do anything special to have it called later.	1662	do anything special to have it called later.
1131		1663
		1664	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1665	ready, it can be beneficial to call this function from loops which submit
		1666	a lot of requests, to make sure the results get processed when they become
		1667	available and not just when the loop is finished and the event loop takes
		1668	over again. This function returns very fast when there are no outstanding
		1669	requests.
		1670
1132	Example: Install an Event watcher that automatically calls	1671	Example: Install an Event watcher that automatically calls
1133	IO::AIO::poll_cb with high priority:	1672	IO::AIO::poll_cb with high priority (more examples can be found in the
		1673	SYNOPSIS section, at the top of this document):
1134		1674
1135	Event->io (fd => IO::AIO::poll_fileno,	1675	Event->io (fd => IO::AIO::poll_fileno,
1136	poll => 'r', async => 1,	1676	poll => 'r', async => 1,
1137	cb => \&IO::AIO::poll_cb);	1677	cb => \&IO::AIO::poll_cb);
		1678
		1679	=item IO::AIO::poll_wait
		1680
		1681	If there are any outstanding requests and none of them in the result
		1682	phase, wait till the result filehandle becomes ready for reading (simply
		1683	does a C<select> on the filehandle. This is useful if you want to
		1684	synchronously wait for some requests to finish).
		1685
		1686	See C<nreqs> for an example.
		1687
		1688	=item IO::AIO::poll
		1689
		1690	Waits until some requests have been handled.
		1691
		1692	Returns the number of requests processed, but is otherwise strictly
		1693	equivalent to:
		1694
		1695	IO::AIO::poll_wait, IO::AIO::poll_cb
		1696
		1697	=item IO::AIO::flush
		1698
		1699	Wait till all outstanding AIO requests have been handled.
		1700
		1701	Strictly equivalent to:
		1702
		1703	IO::AIO::poll_wait, IO::AIO::poll_cb
		1704	while IO::AIO::nreqs;
1138		1705
1139	=item IO::AIO::max_poll_reqs $nreqs	1706	=item IO::AIO::max_poll_reqs $nreqs
1140		1707
1141	=item IO::AIO::max_poll_time $seconds	1708	=item IO::AIO::max_poll_time $seconds
1142		1709
…		…
1167	# use a low priority so other tasks have priority	1734	# use a low priority so other tasks have priority
1168	Event->io (fd => IO::AIO::poll_fileno,	1735	Event->io (fd => IO::AIO::poll_fileno,
1169	poll => 'r', nice => 1,	1736	poll => 'r', nice => 1,
1170	cb => &IO::AIO::poll_cb);	1737	cb => &IO::AIO::poll_cb);
1171		1738
1172	=item IO::AIO::poll_wait
1173
1174	If there are any outstanding requests and none of them in the result
1175	phase, wait till the result filehandle becomes ready for reading (simply
1176	does a C<select> on the filehandle. This is useful if you want to
1177	synchronously wait for some requests to finish).
1178
1179	See C<nreqs> for an example.
1180
1181	=item IO::AIO::poll
1182
1183	Waits until some requests have been handled.
1184
1185	Returns the number of requests processed, but is otherwise strictly
1186	equivalent to:
1187
1188	IO::AIO::poll_wait, IO::AIO::poll_cb
1189
1190	=item IO::AIO::flush
1191
1192	Wait till all outstanding AIO requests have been handled.
1193
1194	Strictly equivalent to:
1195
1196	IO::AIO::poll_wait, IO::AIO::poll_cb
1197	while IO::AIO::nreqs;
1198
1199	=back	1739	=back
1200		1740
1201	=head3 CONTROLLING THE NUMBER OF THREADS	1741	=head3 CONTROLLING THE NUMBER OF THREADS
1202		1742
1203	=over	1743	=over
…		…
1236		1776
1237	Under normal circumstances you don't need to call this function.	1777	Under normal circumstances you don't need to call this function.
1238		1778
1239	=item IO::AIO::max_idle $nthreads	1779	=item IO::AIO::max_idle $nthreads
1240		1780
1241	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1781	Limit the number of threads (default: 4) that are allowed to idle
1242	threads that did not get a request to process within 10 seconds). That	1782	(i.e., threads that did not get a request to process within the idle
1243	means if a thread becomes idle while C<$nthreads> other threads are also	1783	timeout (default: 10 seconds). That means if a thread becomes idle while
1244	idle, it will free its resources and exit.	1784	C<$nthreads> other threads are also idle, it will free its resources and
		1785	exit.
1245		1786
1246	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1787	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1247	to allow for extremely high load situations, but want to free resources	1788	to allow for extremely high load situations, but want to free resources
1248	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1789	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1249		1790
1250	The default is probably ok in most situations, especially if thread	1791	The default is probably ok in most situations, especially if thread
1251	creation is fast. If thread creation is very slow on your system you might	1792	creation is fast. If thread creation is very slow on your system you might
1252	want to use larger values.	1793	want to use larger values.
1253		1794
		1795	=item IO::AIO::idle_timeout $seconds
		1796
		1797	Sets the minimum idle timeout (default 10) after which worker threads are
		1798	allowed to exit. SEe C<IO::AIO::max_idle>.
		1799
1254	=item IO::AIO::max_outstanding $maxreqs	1800	=item IO::AIO::max_outstanding $maxreqs
		1801
		1802	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1803	you do queue up more than this number of requests, the next call to
		1804	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1805	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1806	longer exceeded.
		1807
		1808	In other words, this setting does not enforce a queue limit, but can be
		1809	used to make poll functions block if the limit is exceeded.
1255		1810
1256	This is a very bad function to use in interactive programs because it	1811	This is a very bad function to use in interactive programs because it
1257	blocks, and a bad way to reduce concurrency because it is inexact: Better	1812	blocks, and a bad way to reduce concurrency because it is inexact: Better
1258	use an C<aio_group> together with a feed callback.	1813	use an C<aio_group> together with a feed callback.
1259		1814
1260	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1815	It's main use is in scripts without an event loop - when you want to stat
1261	do queue up more than this number of requests, the next call to the	1816	a lot of files, you can write somehting like this:
1262	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1263	function will block until the limit is no longer exceeded.
1264		1817
1265	The default value is very large, so there is no practical limit on the	1818	IO::AIO::max_outstanding 32;
1266	number of outstanding requests.
1267		1819
1268	You can still queue as many requests as you want. Therefore,	1820	for my $path (...) {
1269	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1821	aio_stat $path , ...;
1270	as a stop gap to shield against fatal memory overflow (with large values).	1822	IO::AIO::poll_cb;
		1823	}
		1824
		1825	IO::AIO::flush;
		1826
		1827	The call to C<poll_cb> inside the loop will normally return instantly, but
		1828	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1829	some requests have been handled. This keeps the loop from pushing a large
		1830	number of C<aio_stat> requests onto the queue.
		1831
		1832	The default value for C<max_outstanding> is very large, so there is no
		1833	practical limit on the number of outstanding requests.
1271		1834
1272	=back	1835	=back
1273		1836
1274	=head3 STATISTICAL INFORMATION	1837	=head3 STATISTICAL INFORMATION
1275		1838
…		…
1295	Returns the number of requests currently in the pending state (executed,	1858	Returns the number of requests currently in the pending state (executed,
1296	but not yet processed by poll_cb).	1859	but not yet processed by poll_cb).
1297		1860
1298	=back	1861	=back
1299		1862
		1863	=head3 MISCELLANEOUS FUNCTIONS
		1864
		1865	IO::AIO implements some functions that might be useful, but are not
		1866	asynchronous.
		1867
		1868	=over 4
		1869
		1870	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1871
		1872	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1873	but is blocking (this makes most sense if you know the input data is
		1874	likely cached already and the output filehandle is set to non-blocking
		1875	operations).
		1876
		1877	Returns the number of bytes copied, or C<-1> on error.
		1878
		1879	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1880
		1881	Simply calls the C<posix_fadvise> function (see its
		1882	manpage for details). The following advice constants are
		1883	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1884	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1885	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1886
		1887	On systems that do not implement C<posix_fadvise>, this function returns
		1888	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1889
		1890	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1891
		1892	Simply calls the C<posix_madvise> function (see its
		1893	manpage for details). The following advice constants are
		1894	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1895	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1896
		1897	On systems that do not implement C<posix_madvise>, this function returns
		1898	ENOSYS, otherwise the return value of C<posix_madvise>.
		1899
		1900	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1901
		1902	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1903	$scalar (see its manpage for details). The following protect
		1904	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1905	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1906
		1907	On systems that do not implement C<mprotect>, this function returns
		1908	ENOSYS, otherwise the return value of C<mprotect>.
		1909
		1910	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1911
		1912	Memory-maps a file (or anonymous memory range) and attaches it to the
		1913	given C<$scalar>, which will act like a string scalar.
		1914
		1915	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1916	change the string length, and most read-only operations such as copying it
		1917	or searching it with regexes and so on.
		1918
		1919	Anything else is unsafe and will, at best, result in memory leaks.
		1920
		1921	The memory map associated with the C<$scalar> is automatically removed
		1922	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1923	C<IO::AIO::munmap> functions are called.
		1924
		1925	This calls the C<mmap>(2) function internally. See your system's manual
		1926	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1927
		1928	The C<$length> must be larger than zero and smaller than the actual
		1929	filesize.
		1930
		1931	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1932	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1933
		1934	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1935	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1936	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1937	(which is set to C<MAP_ANON> if your system only provides this
		1938	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1939	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1940	C<IO::AIO::MAP_NONBLOCK>
		1941
		1942	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1943
		1944	C<$offset> is the offset from the start of the file - it generally must be
		1945	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1946
		1947	Example:
		1948
		1949	use Digest::MD5;
		1950	use IO::AIO;
		1951
		1952	open my $fh, "<verybigfile"
		1953	or die "$!";
		1954
		1955	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1956	or die "verybigfile: $!";
		1957
		1958	my $fast_md5 = md5 $data;
		1959
		1960	=item IO::AIO::munmap $scalar
		1961
		1962	Removes a previous mmap and undefines the C<$scalar>.
		1963
		1964	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1965
		1966	Calls the C<munlock> function, undoing the effects of a previous
		1967	C<aio_mlock> call (see its description for details).
		1968
		1969	=item IO::AIO::munlockall
		1970
		1971	Calls the C<munlockall> function.
		1972
		1973	On systems that do not implement C<munlockall>, this function returns
		1974	ENOSYS, otherwise the return value of C<munlockall>.
		1975
		1976	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		1977
		1978	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		1979	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		1980	should be the file offset.
		1981
		1982	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		1983	silently corrupt the data in this case.
		1984
		1985	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		1986	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		1987	C<IO::AIO::SPLICE_F_GIFT>.
		1988
		1989	See the C<splice(2)> manpage for details.
		1990
		1991	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		1992
		1993	Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the
		1994	description for C<IO::AIO::splice> above for details.
		1995
		1996	=back
		1997
1300	=cut	1998	=cut
1301		1999
1302	min_parallel 8;	2000	min_parallel 8;
1303		2001
1304	END { flush }	2002	END { flush }
1305		2003
1306	1;	2004	1;
1307		2005
		2006	=head1 EVENT LOOP INTEGRATION
		2007
		2008	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2009	automatically into many event loops:
		2010
		2011	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2012	use AnyEvent::AIO;
		2013
		2014	You can also integrate IO::AIO manually into many event loops, here are
		2015	some examples of how to do this:
		2016
		2017	# EV integration
		2018	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2019
		2020	# Event integration
		2021	Event->io (fd => IO::AIO::poll_fileno,
		2022	poll => 'r',
		2023	cb => \&IO::AIO::poll_cb);
		2024
		2025	# Glib/Gtk2 integration
		2026	add_watch Glib::IO IO::AIO::poll_fileno,
		2027	in => sub { IO::AIO::poll_cb; 1 };
		2028
		2029	# Tk integration
		2030	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2031	readable => \&IO::AIO::poll_cb);
		2032
		2033	# Danga::Socket integration
		2034	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2035	\&IO::AIO::poll_cb);
		2036
1308	=head2 FORK BEHAVIOUR	2037	=head2 FORK BEHAVIOUR
1309		2038
1310	This module should do "the right thing" when the process using it forks:	2039	Usage of pthreads in a program changes the semantics of fork
		2040	considerably. Specifically, only async-safe functions can be called after
		2041	fork. Perl doesn't know about this, so in general, you cannot call fork
		2042	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2043	pthreads, so this applies, but many other extensions and (for inexplicable
		2044	reasons) perl itself often is linked against pthreads, so this limitation
		2045	applies to quite a lot of perls.
1311		2046
1312	Before the fork, IO::AIO enters a quiescent state where no requests	2047	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1313	can be added in other threads and no results will be processed. After	2048	only works in the process that loaded it. Forking is fully supported, but
1314	the fork the parent simply leaves the quiescent state and continues	2049	using IO::AIO in the child is not.
1315	request/result processing, while the child frees the request/result queue
1316	(so that the requests started before the fork will only be handled in the
1317	parent). Threads will be started on demand until the limit set in the
1318	parent process has been reached again.
1319		2050
1320	In short: the parent will, after a short pause, continue as if fork had	2051	You might get around by not I<using> IO::AIO before (or after)
1321	not been called, while the child will act as if IO::AIO has not been used	2052	forking. You could also try to call the L<IO::AIO::reinit> function in the
1322	yet.	2053	child:
		2054
		2055	=over 4
		2056
		2057	=item IO::AIO::reinit
		2058
		2059	Abandons all current requests and I/O threads and simply reinitialises all
		2060	data structures. This is not an operation supported by any standards, but
		2061	happens to work on GNU/Linux and some newer BSD systems.
		2062
		2063	The only reasonable use for this function is to call it after forking, if
		2064	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2065	the process will result in undefined behaviour. Calling it at any time
		2066	will also result in any undefined (by POSIX) behaviour.
		2067
		2068	=back
1323		2069
1324	=head2 MEMORY USAGE	2070	=head2 MEMORY USAGE
1325		2071
1326	Per-request usage:	2072	Per-request usage:
1327		2073

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