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Revision 1.69 by root, Tue Oct 24 03:40:25 2006 UTC vs.
Revision 1.207 by root, Mon Jul 25 16:50:33 2011 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) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
25	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
26		27
27	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
28	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
29		30
30	# AnyEvent integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33
34	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',
37	cb => \&IO::AIO::poll_cb);
38
39	# Glib/Gtk2 integration
40	add_watch Glib::IO IO::AIO::poll_fileno,
41	in => sub { IO::AIO::poll_cb; 1 };
42
43	# Tk integration
44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
45	readable => \&IO::AIO::poll_cb);
46
47	# Danga::Socket integration
48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
49	\&IO::AIO::poll_cb);
50
51	=head1 DESCRIPTION	31	=head1 DESCRIPTION
52		32
53	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
54	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>).
55		36
		37	Asynchronous means that operations that can normally block your program
		38	(e.g. reading from disk) will be done asynchronously: the operation
		39	will still block, but you can do something else in the meantime. This
		40	is extremely useful for programs that need to stay interactive even
		41	when doing heavy I/O (GUI programs, high performance network servers
		42	etc.), but can also be used to easily do operations in parallel that are
		43	normally done sequentially, e.g. stat'ing many files, which is much faster
		44	on a RAID volume or over NFS when you do a number of stat operations
		45	concurrently.
		46
		47	While most of this works on all types of file descriptors (for
		48	example sockets), using these functions on file descriptors that
		49	support nonblocking operation (again, sockets, pipes etc.) is
		50	very inefficient. Use an event loop for that (such as the L<EV>
		51	module): IO::AIO will naturally fit into such an event loop itself.
		52
56	Currently, a number of threads are started that execute your read/writes	53	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	54	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	55	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	56	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	57	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	59	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	60	aio_write, so the remaining functionality would have to be implemented
		61	using threads anyway.
64		62
65	Although the module will work with in the presence of other threads,	63	Although the module will work in the presence of other (Perl-) threads,
66	it is currently not reentrant in any way, so use appropriate locking	64	it is currently not reentrant in any way, so use appropriate locking
67	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
68	call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
69		67
		68	=head2 EXAMPLE
		69
		70	This is a simple example that uses the EV module and loads
		71	F</etc/passwd> asynchronously:
		72
		73	use Fcntl;
		74	use EV;
		75	use IO::AIO;
		76
		77	# register the IO::AIO callback with EV
		78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		79
		80	# queue the request to open /etc/passwd
		81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
		82	my $fh = shift
		83	or die "error while opening: $!";
		84
		85	# stat'ing filehandles is generally non-blocking
		86	my $size = -s $fh;
		87
		88	# queue a request to read the file
		89	my $contents;
		90	aio_read $fh, 0, $size, $contents, 0, sub {
		91	$_[0] == $size
		92	or die "short read: $!";
		93
		94	close $fh;
		95
		96	# file contents now in $contents
		97	print $contents;
		98
		99	# exit event loop and program
		100	EV::unloop;
		101	};
		102	};
		103
		104	# possibly queue up other requests, or open GUI windows,
		105	# check for sockets etc. etc.
		106
		107	# process events as long as there are some:
		108	EV::loop;
		109
		110	=head1 REQUEST ANATOMY AND LIFETIME
		111
		112	Every C<aio_*> function creates a request. which is a C data structure not
		113	directly visible to Perl.
		114
		115	If called in non-void context, every request function returns a Perl
		116	object representing the request. In void context, nothing is returned,
		117	which saves a bit of memory.
		118
		119	The perl object is a fairly standard ref-to-hash object. The hash contents
		120	are not used by IO::AIO so you are free to store anything you like in it.
		121
		122	During their existance, aio requests travel through the following states,
		123	in order:
		124
		125	=over 4
		126
		127	=item ready
		128
		129	Immediately after a request is created it is put into the ready state,
		130	waiting for a thread to execute it.
		131
		132	=item execute
		133
		134	A thread has accepted the request for processing and is currently
		135	executing it (e.g. blocking in read).
		136
		137	=item pending
		138
		139	The request has been executed and is waiting for result processing.
		140
		141	While request submission and execution is fully asynchronous, result
		142	processing is not and relies on the perl interpreter calling C<poll_cb>
		143	(or another function with the same effect).
		144
		145	=item result
		146
		147	The request results are processed synchronously by C<poll_cb>.
		148
		149	The C<poll_cb> function will process all outstanding aio requests by
		150	calling their callbacks, freeing memory associated with them and managing
		151	any groups they are contained in.
		152
		153	=item done
		154
		155	Request has reached the end of its lifetime and holds no resources anymore
		156	(except possibly for the Perl object, but its connection to the actual
		157	aio request is severed and calling its methods will either do nothing or
		158	result in a runtime error).
		159
		160	=back
		161
70	=cut	162	=cut
71		163
72	package IO::AIO;	164	package IO::AIO;
73		165
74	no warnings;	166	use Carp ();
75	use strict 'vars';	167
		168	use common::sense;
76		169
77	use base 'Exporter';	170	use base 'Exporter';
78		171
79	BEGIN {	172	BEGIN {
80	our $VERSION = '2.0';	173	our $VERSION = '4.0';
81		174
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
		178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
		179	aio_pathsync aio_readahead
		180	aio_rename aio_link aio_move aio_copy aio_group
		181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
85	aio_group aio_nop);	184	aio_statvfs);
		185
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	186	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	187	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	188	min_parallel max_parallel max_idle idle_timeout
		189	nreqs nready npending nthreads
		190	max_poll_time max_poll_reqs
		191	sendfile fadvise madvise
		192	mmap munmap munlock munlockall);
		193
		194	push @AIO_REQ, qw(aio_busy); # not exported
89		195
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		197
92	require XSLoader;	198	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	199	XSLoader::load ("IO::AIO", $VERSION);
94	}	200	}
95		201
96	=head1 FUNCTIONS	202	=head1 FUNCTIONS
97		203
		204	=head2 QUICK OVERVIEW
		205
		206	This section simply lists the prototypes of the most important functions
		207	for quick reference. See the following sections for function-by-function
		208	documentation.
		209
		210	aio_open $pathname, $flags, $mode, $callback->($fh)
		211	aio_close $fh, $callback->($status)
		212	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		214	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		215	aio_readahead $fh,$offset,$length, $callback->($retval)
		216	aio_stat $fh_or_path, $callback->($status)
		217	aio_lstat $fh, $callback->($status)
		218	aio_statvfs $fh_or_path, $callback->($statvfs)
		219	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		220	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		221	aio_truncate $fh_or_path, $offset, $callback->($status)
		222	aio_chmod $fh_or_path, $mode, $callback->($status)
		223	aio_unlink $pathname, $callback->($status)
		224	aio_mknod $path, $mode, $dev, $callback->($status)
		225	aio_link $srcpath, $dstpath, $callback->($status)
		226	aio_symlink $srcpath, $dstpath, $callback->($status)
		227	aio_readlink $path, $callback->($link)
		228	aio_realpath $path, $callback->($link)
		229	aio_rename $srcpath, $dstpath, $callback->($status)
		230	aio_mkdir $pathname, $mode, $callback->($status)
		231	aio_rmdir $pathname, $callback->($status)
		232	aio_readdir $pathname, $callback->($entries)
		233	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		234	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		235	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		236	aio_load $path, $data, $callback->($status)
		237	aio_copy $srcpath, $dstpath, $callback->($status)
		238	aio_move $srcpath, $dstpath, $callback->($status)
		239	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		240	aio_rmtree $path, $callback->($status)
		241	aio_sync $callback->($status)
		242	aio_syncfs $fh, $callback->($status)
		243	aio_fsync $fh, $callback->($status)
		244	aio_fdatasync $fh, $callback->($status)
		245	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		246	aio_pathsync $path, $callback->($status)
		247	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		248	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		249	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		250	aio_mlockall $flags, $callback->($status)
		251	aio_group $callback->(...)
		252	aio_nop $callback->()
		253
		254	$prev_pri = aioreq_pri [$pri]
		255	aioreq_nice $pri_adjust
		256
		257	IO::AIO::poll_wait
		258	IO::AIO::poll_cb
		259	IO::AIO::poll
		260	IO::AIO::flush
		261	IO::AIO::max_poll_reqs $nreqs
		262	IO::AIO::max_poll_time $seconds
		263	IO::AIO::min_parallel $nthreads
		264	IO::AIO::max_parallel $nthreads
		265	IO::AIO::max_idle $nthreads
		266	IO::AIO::idle_timeout $seconds
		267	IO::AIO::max_outstanding $maxreqs
		268	IO::AIO::nreqs
		269	IO::AIO::nready
		270	IO::AIO::npending
		271
		272	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		273	IO::AIO::fadvise $fh, $offset, $len, $advice
		274	IO::AIO::madvise $scalar, $offset, $length, $advice
		275	IO::AIO::mprotect $scalar, $offset, $length, $protect
		276	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		277	IO::AIO::munlockall
		278
98	=head2 AIO FUNCTIONS	279	=head2 AIO REQUEST FUNCTIONS
99		280
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	281	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	282	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	283	and they all accept an additional (and optional) C<$callback> argument
103	which must be a code reference. This code reference will get called with	284	which must be a code reference. This code reference will get called with
104	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	285	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
105	perl, which usually delivers "false") as it's sole argument when the given	286	perl, which usually delivers "false") as its sole argument after the given
106	syscall has been executed asynchronously.	287	syscall has been executed asynchronously.
107		288
108	All functions expecting a filehandle keep a copy of the filehandle	289	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	290	internally until the request has finished.
110		291
111	All requests return objects of type L<IO::AIO::REQ> that allow further	292	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	293	further manipulation of those requests while they are in-flight.
113		294
114	The pathnames you pass to these routines I<must> be absolute and	295	The pathnames you pass to these routines I<must> be absolute and
115	encoded in byte form. The reason for the former is that at the time the	296	encoded as octets. The reason for the former is that at the time the
116	request is being executed, the current working directory could have	297	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	298	changed. Alternatively, you can make sure that you never change the
118	current working directory.	299	current working directory anywhere in the program and then use relative
		300	paths.
119		301
120	To encode pathnames to byte form, either make sure you either: a)	302	To encode pathnames as octets, either make sure you either: a) always pass
121	always pass in filenames you got from outside (command line, readdir	303	in filenames you got from outside (command line, readdir etc.) without
122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	304	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
123	your pathnames to the locale (or other) encoding in effect in the user	305	your pathnames to the locale (or other) encoding in effect in the user
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	306	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	307	use something else to ensure your scalar has the correct contents.
		308
		309	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		310	handles correctly whether it is set or not.
126		311
127	=over 4	312	=over 4
128		313
129	=item aioreq_pri $pri	314	=item $prev_pri = aioreq_pri [$pri]
130		315
131	Sets the priority for the next aio request. The default priority	316	Returns the priority value that would be used for the next request and, if
		317	C<$pri> is given, sets the priority for the next aio request.
		318
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	319	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	320	and C<4>, respectively. Requests with higher priority will be serviced
		321	first.
134		322
135	The priority will be reset to C<0> after each call to one of the C<aio_>	323	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	324	functions.
137		325
138	Example: open a file with low priority, then read something from it with	326	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	327	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	328	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	335	aio_read $_[0], ..., sub {
148	...	336	...
149	};	337	};
150	};	338	};
151		339
		340
152	=item aioreq_nice $pri_adjust	341	=item aioreq_nice $pri_adjust
153		342
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	343	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	344	priority, so the effect is cumulative.
		345
156		346
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	347	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		348
159	Asynchronously open or create a file and call the callback with a newly	349	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	350	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	356	list. They are the same as used by C<sysopen>.
167		357
168	Likewise, C<$mode> specifies the mode of the newly created file, if it	358	Likewise, C<$mode> specifies the mode of the newly created file, if it
169	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	359	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
170	except that it is mandatory (i.e. use C<0> if you don't create new files,	360	except that it is mandatory (i.e. use C<0> if you don't create new files,
171	and C<0666> or C<0777> if you do).	361	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		362	by the umask in effect then the request is being executed, so better never
		363	change the umask.
172		364
173	Example:	365	Example:
174		366
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	367	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
176	if ($_[0]) {	368	if ($_[0]) {
177	print "open successful, fh is $_[0]\n";	369	print "open successful, fh is $_[0]\n";
178	...	370	...
179	} else {	371	} else {
180	die "open failed: $!\n";	372	die "open failed: $!\n";
181	}	373	}
182	};	374	};
183		375
		376	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		377	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		378	following POSIX and non-POSIX constants are available (missing ones on
		379	your system are, as usual, C<0>):
		380
		381	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		382	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		383	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		384
		385
184	=item aio_close $fh, $callback->($status)	386	=item aio_close $fh, $callback->($status)
185		387
186	Asynchronously close a file and call the callback with the result	388	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	389	code.
188	filehandle here, as perl will likely close the file descriptor another
189	time when the filehandle is destroyed. Normally, you can safely call perls
190	C<close> or just let filehandles go out of scope.
191		390
192	This is supposed to be a bug in the API, so that might change. It's	391	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
193	therefore best to avoid this function.	392	closing the file descriptor associated with the filehandle itself.
		393
		394	Therefore, C<aio_close> will not close the filehandle - instead it will
		395	use dup2 to overwrite the file descriptor with the write-end of a pipe
		396	(the pipe fd will be created on demand and will be cached).
		397
		398	Or in other words: the file descriptor will be closed, but it will not be
		399	free for reuse until the perl filehandle is closed.
		400
		401	=cut
194		402
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	403	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		404
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	405	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		406
199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	407	Reads or writes C<$length> bytes from or to the specified C<$fh> and
200	into the scalar given by C<data> and offset C<dataoffset> and calls the	408	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
201	callback without the actual number of bytes read (or -1 on error, just	409	and calls the callback without the actual number of bytes read (or -1 on
202	like the syscall).	410	error, just like the syscall).
		411
		412	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		413	offset plus the actual number of bytes read.
		414
		415	If C<$offset> is undefined, then the current file descriptor offset will
		416	be used (and updated), otherwise the file descriptor offset will not be
		417	changed by these calls.
		418
		419	If C<$length> is undefined in C<aio_write>, use the remaining length of
		420	C<$data>.
		421
		422	If C<$dataoffset> is less than zero, it will be counted from the end of
		423	C<$data>.
203		424
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	425	The C<$data> scalar I<MUST NOT> be modified in any way while the request
205	is outstanding. Modifying it can result in segfaults or WW3 (if the	426	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	427	the necessary/optional hardware is installed).
207		428
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	429	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	430	offset C<0> within the scalar:
210		431
211	aio_read $fh, 7, 15, $buffer, 0, sub {	432	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	433	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	434	print "read $_[0] bytes: <$buffer>\n";
214	};	435	};
215		436
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	[EXPERIMENTAL due to internal aio_group use]
219
220	Try to move the I<file> (directories not supported as either source or
221	destination) from C<$srcpath> to C<$dstpath> and call the callback with
222	the C<0> (error) or C<-1> ok.
223
224	This is a composite request that tries to rename(2) the file first. If
225	rename files with C<EXDEV>, it creates the destination file with mode 0200
226	and copies the contents of the source file into it using C<aio_sendfile>,
227	followed by restoring atime, mtime, access mode and uid/gid, in that
228	order, and unlinking the C<$srcpath>.
229
230	If an error occurs, the partial destination file will be unlinked, if
231	possible, except when setting atime, mtime, access mode and uid/gid, where
232	errors are being ignored.
233
234	=cut
235
236	sub aio_move($$$) {
237	my ($src, $dst, $cb) = @_;
238
239	my $grp = aio_group $cb;
240
241	add $grp aio_rename $src, $dst, sub {
242	if ($_[0] && $! == EXDEV) {
243	add $grp aio_open $src, O_RDONLY, 0, sub {
244	if (my $src_fh = $_[0]) {
245	my @stat = stat $src_fh;
246
247	add $grp aio_open $dst, O_WRONLY, 0200, sub {
248	if (my $dst_fh = $_[0]) {
249	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
250	close $src_fh;
251
252	if ($_[0] == $stat[7]) {
253	utime $stat[8], $stat[9], $dst;
254	chmod $stat[2] & 07777, $dst_fh;
255	chown $stat[4], $stat[5], $dst_fh;
256	close $dst_fh;
257
258	add $grp aio_unlink $src, sub {
259	$grp->result ($_[0]);
260	};
261	} else {
262	my $errno = $!;
263	add $grp aio_unlink $dst, sub {
264	$! = $errno;
265	$grp->result (-1);
266	};
267	}
268	};
269	} else {
270	$grp->result (-1);
271	}
272	},
273
274	} else {
275	$grp->result (-1);
276	}
277	};
278	} else {
279	$grp->result ($_[0]);
280	}
281	};
282
283	$grp
284	}
285		437
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	438	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		439
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	440	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
289	reading at byte offset C<$in_offset>, and starts writing at the current	441	reading at byte offset C<$in_offset>, and starts writing at the current
290	file offset of C<$out_fh>. Because of that, it is not safe to issue more	442	file offset of C<$out_fh>. Because of that, it is not safe to issue more
291	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	443	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
292	other.	444	other. The same C<$in_fh> works fine though, as this function does not
		445	move or use the file offset of C<$in_fh>.
293		446
		447	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		448	are written, and there is no way to find out how many more bytes have been
		449	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		450	number of bytes written to C<$out_fh>. Only if the result value equals
		451	C<$length> one can assume that C<$length> bytes have been read.
		452
		453	Unlike with other C<aio_> functions, it makes a lot of sense to use
		454	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		455	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		456	the socket I/O will be non-blocking. Note, however, that you can run
		457	into a trap where C<aio_sendfile> reads some data with readahead, then
		458	fails to write all data, and when the socket is ready the next time, the
		459	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		460	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		461	resource usage.
		462
294	This call tries to make use of a native C<sendfile> syscall to provide	463	This call tries to make use of a native C<sendfile>-like syscall to
295	zero-copy operation. For this to work, C<$out_fh> should refer to a	464	provide zero-copy operation. For this to work, C<$out_fh> should refer to
296	socket, and C<$in_fh> should refer to mmap'able file.	465	a socket, and C<$in_fh> should refer to an mmap'able file.
297		466
298	If the native sendfile call fails or is not implemented, it will be	467	If a native sendfile cannot be found or it fails with C<ENOSYS>,
299	emulated, so you can call C<aio_sendfile> on any type of filehandle	468	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		469	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
300	regardless of the limitations of the operating system.	470	type of filehandle regardless of the limitations of the operating system.
301		471
302	Please note, however, that C<aio_sendfile> can read more bytes from	472	As native sendfile syscalls (as practically any non-POSIX interface hacked
303	C<$in_fh> than are written, and there is no way to find out how many	473	together in a hurry to improve benchmark numbers) tend to be rather buggy
304	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	474	on many systems, this implementation tries to work around some known bugs
305	provides the number of bytes written to C<$out_fh>. Only if the result	475	in Linux and FreeBSD kernels (probably others, too), but that might fail,
306	value equals C<$length> one can assume that C<$length> bytes have been	476	so you really really should check the return value of C<aio_sendfile> -
307	read.	477	fewre bytes than expected might have been transferred.
		478
308		479
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	480	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		481
311	C<aio_readahead> populates the page cache with data from a file so that	482	C<aio_readahead> populates the page cache with data from a file so that
312	subsequent reads from that file will not block on disk I/O. The C<$offset>	483	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
318	file. The current file offset of the file is left unchanged.	489	file. The current file offset of the file is left unchanged.
319		490
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	491	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
321	emulated by simply reading the data, which would have a similar effect.	492	emulated by simply reading the data, which would have a similar effect.
322		493
		494
323	=item aio_stat $fh_or_path, $callback->($status)	495	=item aio_stat $fh_or_path, $callback->($status)
324		496
325	=item aio_lstat $fh, $callback->($status)	497	=item aio_lstat $fh, $callback->($status)
326		498
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	499	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
332	for an explanation.	504	for an explanation.
333		505
334	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	506	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
335	error when stat'ing a large file, the results will be silently truncated	507	error when stat'ing a large file, the results will be silently truncated
336	unless perl itself is compiled with large file support.	508	unless perl itself is compiled with large file support.
		509
		510	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		511	following constants and functions (if not implemented, the constants will
		512	be C<0> and the functions will either C<croak> or fall back on traditional
		513	behaviour).
		514
		515	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		516	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		517	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
337		518
338	Example: Print the length of F</etc/passwd>:	519	Example: Print the length of F</etc/passwd>:
339		520
340	aio_stat "/etc/passwd", sub {	521	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	522	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	523	print "size is ", -s _, "\n";
343	};	524	};
344		525
		526
		527	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		528
		529	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		530	whether a file handle or path was passed.
		531
		532	On success, the callback is passed a hash reference with the following
		533	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		534	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		535	is passed.
		536
		537	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		538	C<ST_NOSUID>.
		539
		540	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		541	their correct value when available, or to C<0> on systems that do
		542	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		543	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		544	C<ST_NODIRATIME> and C<ST_RELATIME>.
		545
		546	Example: stat C</wd> and dump out the data if successful.
		547
		548	aio_statvfs "/wd", sub {
		549	my $f = $_[0]
		550	or die "statvfs: $!";
		551
		552	use Data::Dumper;
		553	say Dumper $f;
		554	};
		555
		556	# result:
		557	{
		558	bsize => 1024,
		559	bfree => 4333064312,
		560	blocks => 10253828096,
		561	files => 2050765568,
		562	flag => 4096,
		563	favail => 2042092649,
		564	bavail => 4333064312,
		565	ffree => 2042092649,
		566	namemax => 255,
		567	frsize => 1024,
		568	fsid => 1810
		569	}
		570
		571
		572	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		573
		574	Works like perl's C<utime> function (including the special case of $atime
		575	and $mtime being undef). Fractional times are supported if the underlying
		576	syscalls support them.
		577
		578	When called with a pathname, uses utimes(2) if available, otherwise
		579	utime(2). If called on a file descriptor, uses futimes(2) if available,
		580	otherwise returns ENOSYS, so this is not portable.
		581
		582	Examples:
		583
		584	# set atime and mtime to current time (basically touch(1)):
		585	aio_utime "path", undef, undef;
		586	# set atime to current time and mtime to beginning of the epoch:
		587	aio_utime "path", time, undef; # undef==0
		588
		589
		590	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		591
		592	Works like perl's C<chown> function, except that C<undef> for either $uid
		593	or $gid is being interpreted as "do not change" (but -1 can also be used).
		594
		595	Examples:
		596
		597	# same as "chown root path" in the shell:
		598	aio_chown "path", 0, -1;
		599	# same as above:
		600	aio_chown "path", 0, undef;
		601
		602
		603	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		604
		605	Works like truncate(2) or ftruncate(2).
		606
		607
		608	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		609
		610	Works like perl's C<chmod> function.
		611
		612
345	=item aio_unlink $pathname, $callback->($status)	613	=item aio_unlink $pathname, $callback->($status)
346		614
347	Asynchronously unlink (delete) a file and call the callback with the	615	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	616	result code.
349		617
		618
		619	=item aio_mknod $path, $mode, $dev, $callback->($status)
		620
		621	[EXPERIMENTAL]
		622
		623	Asynchronously create a device node (or fifo). See mknod(2).
		624
		625	The only (POSIX-) portable way of calling this function is:
		626
		627	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		628
		629	See C<aio_stat> for info about some potentially helpful extra constants
		630	and functions.
		631
350	=item aio_link $srcpath, $dstpath, $callback->($status)	632	=item aio_link $srcpath, $dstpath, $callback->($status)
351		633
352	Asynchronously create a new link to the existing object at C<$srcpath> at	634	Asynchronously create a new link to the existing object at C<$srcpath> at
353	the path C<$dstpath> and call the callback with the result code.	635	the path C<$dstpath> and call the callback with the result code.
354		636
		637
355	=item aio_symlink $srcpath, $dstpath, $callback->($status)	638	=item aio_symlink $srcpath, $dstpath, $callback->($status)
356		639
357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	640	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
358	the path C<$dstpath> and call the callback with the result code.	641	the path C<$dstpath> and call the callback with the result code.
359		642
		643
		644	=item aio_readlink $path, $callback->($link)
		645
		646	Asynchronously read the symlink specified by C<$path> and pass it to
		647	the callback. If an error occurs, nothing or undef gets passed to the
		648	callback.
		649
		650
		651	=item aio_realpath $path, $callback->($path)
		652
		653	Asynchronously make the path absolute and resolve any symlinks in
		654	C<$path>. The resulting path only consists of directories (Same as
		655	L<Cwd::realpath>).
		656
		657	This request can be used to get the absolute path of the current working
		658	directory by passing it a path of F<.> (a single dot).
		659
		660
360	=item aio_rename $srcpath, $dstpath, $callback->($status)	661	=item aio_rename $srcpath, $dstpath, $callback->($status)
361		662
362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	663	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363	rename(2) and call the callback with the result code.	664	rename(2) and call the callback with the result code.
364		665
		666
		667	=item aio_mkdir $pathname, $mode, $callback->($status)
		668
		669	Asynchronously mkdir (create) a directory and call the callback with
		670	the result code. C<$mode> will be modified by the umask at the time the
		671	request is executed, so do not change your umask.
		672
		673
365	=item aio_rmdir $pathname, $callback->($status)	674	=item aio_rmdir $pathname, $callback->($status)
366		675
367	Asynchronously rmdir (delete) a directory and call the callback with the	676	Asynchronously rmdir (delete) a directory and call the callback with the
368	result code.	677	result code.
		678
369		679
370	=item aio_readdir $pathname, $callback->($entries)	680	=item aio_readdir $pathname, $callback->($entries)
371		681
372	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	682	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
373	directory (i.e. opendir + readdir + closedir). The entries will not be	683	directory (i.e. opendir + readdir + closedir). The entries will not be
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	684	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		685
376	The callback a single argument which is either C<undef> or an array-ref	686	The callback is passed a single argument which is either C<undef> or an
377	with the filenames.	687	array-ref with the filenames.
		688
		689
		690	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		691
		692	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		693	tune behaviour and output format. In case of an error, C<$entries> will be
		694	C<undef>.
		695
		696	The flags are a combination of the following constants, ORed together (the
		697	flags will also be passed to the callback, possibly modified):
		698
		699	=over 4
		700
		701	=item IO::AIO::READDIR_DENTS
		702
		703	When this flag is off, then the callback gets an arrayref consisting of
		704	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		705	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		706	entry in more detail.
		707
		708	C<$name> is the name of the entry.
		709
		710	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		711
		712	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		713	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		714	C<IO::AIO::DT_WHT>.
		715
		716	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		717	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		718	scalars are read-only: you can not modify them.
		719
		720	C<$inode> is the inode number (which might not be exact on systems with 64
		721	bit inode numbers and 32 bit perls). This field has unspecified content on
		722	systems that do not deliver the inode information.
		723
		724	=item IO::AIO::READDIR_DIRS_FIRST
		725
		726	When this flag is set, then the names will be returned in an order where
		727	likely directories come first, in optimal stat order. This is useful when
		728	you need to quickly find directories, or you want to find all directories
		729	while avoiding to stat() each entry.
		730
		731	If the system returns type information in readdir, then this is used
		732	to find directories directly. Otherwise, likely directories are names
		733	beginning with ".", or otherwise names with no dots, of which names with
		734	short names are tried first.
		735
		736	=item IO::AIO::READDIR_STAT_ORDER
		737
		738	When this flag is set, then the names will be returned in an order
		739	suitable for stat()'ing each one. That is, when you plan to stat()
		740	all files in the given directory, then the returned order will likely
		741	be fastest.
		742
		743	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		744	the likely dirs come first, resulting in a less optimal stat order.
		745
		746	=item IO::AIO::READDIR_FOUND_UNKNOWN
		747
		748	This flag should not be set when calling C<aio_readdirx>. Instead, it
		749	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		750	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		751	C<$type>'s are known, which can be used to speed up some algorithms.
		752
		753	=back
		754
		755
		756	=item aio_load $path, $data, $callback->($status)
		757
		758	This is a composite request that tries to fully load the given file into
		759	memory. Status is the same as with aio_read.
		760
		761	=cut
		762
		763	sub aio_load($$;$) {
		764	my ($path, undef, $cb) = @_;
		765	my $data = \$_[1];
		766
		767	my $pri = aioreq_pri;
		768	my $grp = aio_group $cb;
		769
		770	aioreq_pri $pri;
		771	add $grp aio_open $path, O_RDONLY, 0, sub {
		772	my $fh = shift
		773	or return $grp->result (-1);
		774
		775	aioreq_pri $pri;
		776	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		777	$grp->result ($_[0]);
		778	};
		779	};
		780
		781	$grp
		782	}
		783
		784	=item aio_copy $srcpath, $dstpath, $callback->($status)
		785
		786	Try to copy the I<file> (directories not supported as either source or
		787	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		788	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		789
		790	This is a composite request that creates the destination file with
		791	mode 0200 and copies the contents of the source file into it using
		792	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		793	uid/gid, in that order.
		794
		795	If an error occurs, the partial destination file will be unlinked, if
		796	possible, except when setting atime, mtime, access mode and uid/gid, where
		797	errors are being ignored.
		798
		799	=cut
		800
		801	sub aio_copy($$;$) {
		802	my ($src, $dst, $cb) = @_;
		803
		804	my $pri = aioreq_pri;
		805	my $grp = aio_group $cb;
		806
		807	aioreq_pri $pri;
		808	add $grp aio_open $src, O_RDONLY, 0, sub {
		809	if (my $src_fh = $_[0]) {
		810	my @stat = stat $src_fh; # hmm, might block over nfs?
		811
		812	aioreq_pri $pri;
		813	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		814	if (my $dst_fh = $_[0]) {
		815	aioreq_pri $pri;
		816	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		817	if ($_[0] == $stat[7]) {
		818	$grp->result (0);
		819	close $src_fh;
		820
		821	my $ch = sub {
		822	aioreq_pri $pri;
		823	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		824	aioreq_pri $pri;
		825	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		826	aioreq_pri $pri;
		827	add $grp aio_close $dst_fh;
		828	}
		829	};
		830	};
		831
		832	aioreq_pri $pri;
		833	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		834	if ($_[0] < 0 && $! == ENOSYS) {
		835	aioreq_pri $pri;
		836	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		837	} else {
		838	$ch->();
		839	}
		840	};
		841	} else {
		842	$grp->result (-1);
		843	close $src_fh;
		844	close $dst_fh;
		845
		846	aioreq $pri;
		847	add $grp aio_unlink $dst;
		848	}
		849	};
		850	} else {
		851	$grp->result (-1);
		852	}
		853	},
		854
		855	} else {
		856	$grp->result (-1);
		857	}
		858	};
		859
		860	$grp
		861	}
		862
		863	=item aio_move $srcpath, $dstpath, $callback->($status)
		864
		865	Try to move the I<file> (directories not supported as either source or
		866	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		867	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		868
		869	This is a composite request that tries to rename(2) the file first; if
		870	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		871	that is successful, unlinks the C<$srcpath>.
		872
		873	=cut
		874
		875	sub aio_move($$;$) {
		876	my ($src, $dst, $cb) = @_;
		877
		878	my $pri = aioreq_pri;
		879	my $grp = aio_group $cb;
		880
		881	aioreq_pri $pri;
		882	add $grp aio_rename $src, $dst, sub {
		883	if ($_[0] && $! == EXDEV) {
		884	aioreq_pri $pri;
		885	add $grp aio_copy $src, $dst, sub {
		886	$grp->result ($_[0]);
		887
		888	unless ($_[0]) {
		889	aioreq_pri $pri;
		890	add $grp aio_unlink $src;
		891	}
		892	};
		893	} else {
		894	$grp->result ($_[0]);
		895	}
		896	};
		897
		898	$grp
		899	}
378		900
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	901	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		902
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	903	Scans a directory (similar to C<aio_readdir>) but additionally tries to
384	separate the entries of directory C<$path> into two sets of names, ones	904	efficiently separate the entries of directory C<$path> into two sets of
385	you can recurse into (directories or links to them), and ones you cannot	905	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	906	recurse into (everything else, including symlinks to directories).
387		907
388	C<aio_scandir> is a composite request that creates of many sub requests_	908	C<aio_scandir> is a composite request that creates of many sub requests_
389	C<$maxreq> specifies the maximum number of outstanding aio requests that	909	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	910	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	911	will be chosen (currently 4).
392		912
393	On error, the callback is called without arguments, otherwise it receives	913	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	914	two array-refs with path-relative entry names.
395		915
396	Example:	916	Example:
…		…
403		923
404	Implementation notes.	924	Implementation notes.
405		925
406	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	926	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
407		927
		928	If readdir returns file type information, then this is used directly to
		929	find directories.
		930
408	After reading the directory, the modification time, size etc. of the	931	Otherwise, after reading the directory, the modification time, size etc.
409	directory before and after the readdir is checked, and if they match (and	932	of the directory before and after the readdir is checked, and if they
410	isn't the current time), the link count will be used to decide how many	933	match (and isn't the current time), the link count will be used to decide
411	entries are directories (if >= 2). Otherwise, no knowledge of the number	934	how many entries are directories (if >= 2). Otherwise, no knowledge of the
412	of subdirectories will be assumed.	935	number of subdirectories will be assumed.
413		936
414	Then entries will be sorted into likely directories (everything without	937	Then entries will be sorted into likely directories a non-initial dot
415	a non-initial dot currently) and likely non-directories (everything	938	currently) and likely non-directories (see C<aio_readdirx>). Then every
416	else). Then every entry plus an appended C</.> will be C<stat>'ed,	939	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
417	likely directories first. If that succeeds, it assumes that the entry	940	in order of their inode numbers. If that succeeds, it assumes that the
418	is a directory or a symlink to directory (which will be checked	941	entry is a directory or a symlink to directory (which will be checked
419	seperately). This is often faster than stat'ing the entry itself because	942	separately). This is often faster than stat'ing the entry itself because
420	filesystems might detect the type of the entry without reading the inode	943	filesystems might detect the type of the entry without reading the inode
421	data (e.g. ext2fs filetype feature).	944	data (e.g. ext2fs filetype feature), even on systems that cannot return
		945	the filetype information on readdir.
422		946
423	If the known number of directories (link count - 2) has been reached, the	947	If the known number of directories (link count - 2) has been reached, the
424	rest of the entries is assumed to be non-directories.	948	rest of the entries is assumed to be non-directories.
425		949
426	This only works with certainty on POSIX (= UNIX) filesystems, which	950	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
430	as those tend to return 0 or 1 as link counts, which disables the	954	as those tend to return 0 or 1 as link counts, which disables the
431	directory counting heuristic.	955	directory counting heuristic.
432		956
433	=cut	957	=cut
434		958
435	sub aio_scandir($$$) {	959	sub aio_scandir($$;$) {
436	my ($path, $maxreq, $cb) = @_;	960	my ($path, $maxreq, $cb) = @_;
437		961
		962	my $pri = aioreq_pri;
		963
438	my $grp = aio_group $cb;	964	my $grp = aio_group $cb;
439		965
440	$maxreq = 6 if $maxreq <= 0;	966	$maxreq = 4 if $maxreq <= 0;
441		967
442	# stat once	968	# stat once
		969	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	970	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	971	return $grp->result () if $_[0];
445	my $now = time;	972	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	973	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		974
448	# read the directory entries	975	# read the directory entries
		976	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	977	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
450	my $entries = shift	978	my $entries = shift
451	or return $grp->result ();	979	or return $grp->result ();
452		980
453	# stat the dir another time	981	# stat the dir another time
		982	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	983	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	984	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		985
457	my $ndirs;	986	my $ndirs;
458		987
459	# take the slow route if anything looks fishy	988	# take the slow route if anything looks fishy
460	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	989	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
461	$ndirs = -1;	990	$ndirs = -1;
462	} else {	991	} else {
463	# if nlink == 2, we are finished	992	# if nlink == 2, we are finished
464	# on non-posix-fs's, we rely on nlink < 2	993	# for non-posix-fs's, we rely on nlink < 2
465	$ndirs = (stat _)[3] - 2	994	$ndirs = (stat _)[3] - 2
466	or return $grp->result ([], $entries);	995	or return $grp->result ([], $entries);
467	}	996	}
468		997
469	# sort into likely dirs and likely nondirs
470	# dirs == files without ".", short entries first
471	$entries = [map $_->[0],
472	sort { $b->[1] cmp $a->[1] }
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];
475
476	my (@dirs, @nondirs);	998	my (@dirs, @nondirs);
477		999
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	1000	my $statgrp = add $grp aio_group sub {
		1001	$grp->result (\@dirs, \@nondirs);
		1002	};
482		1003
483	$schedcb = sub {	1004	limit $statgrp $maxreq;
484	if (@$entries) {	1005	feed $statgrp sub {
485	if ($nreq < $maxreq) {	1006	return unless @$entries;
486	my $ent = pop @$entries;	1007	my $entry = shift @$entries;
		1008
		1009	aioreq_pri $pri;
		1010	add $statgrp aio_stat "$path/$entry/.", sub {
		1011	if ($_[0] < 0) {
		1012	push @nondirs, $entry;
		1013	} else {
		1014	# need to check for real directory
		1015	aioreq_pri $pri;
		1016	add $statgrp aio_lstat "$path/$entry", sub {
		1017	if (-d _) {
		1018	push @dirs, $entry;
		1019
		1020	unless (--$ndirs) {
		1021	push @nondirs, @$entries;
		1022	feed $statgrp;
		1023	}
		1024	} else {
		1025	push @nondirs, $entry;
		1026	}
487	$nreq++;	1027	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	1028	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	1029	};
497	};	1030	};
498	$statcb = sub {
499	my ($status, $entry) = @_;
500
501	if ($status < 0) {
502	$nreq--;
503	push @nondirs, $entry;
504	&$schedcb;
505	} else {
506	# need to check for real directory
507	add $grp aio_lstat "$path/$entry", sub {
508	$nreq--;
509
510	if (-d _) {
511	push @dirs, $entry;
512
513	if (!--$ndirs) {
514	push @nondirs, @$entries;
515	$entries = [];
516	}
517	} else {
518	push @nondirs, $entry;
519	}
520
521	&$schedcb;
522	}
523	}
524	};
525
526	&$schedcb while @$entries && $nreq < $maxreq;
527	};	1031	};
528	};	1032	};
529	};	1033	};
530		1034
531	$grp	1035	$grp
532	}	1036	}
533		1037
		1038	=item aio_rmtree $path, $callback->($status)
		1039
		1040	Delete a directory tree starting (and including) C<$path>, return the
		1041	status of the final C<rmdir> only. This is a composite request that
		1042	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1043	everything else.
		1044
		1045	=cut
		1046
		1047	sub aio_rmtree;
		1048	sub aio_rmtree($;$) {
		1049	my ($path, $cb) = @_;
		1050
		1051	my $pri = aioreq_pri;
		1052	my $grp = aio_group $cb;
		1053
		1054	aioreq_pri $pri;
		1055	add $grp aio_scandir $path, 0, sub {
		1056	my ($dirs, $nondirs) = @_;
		1057
		1058	my $dirgrp = aio_group sub {
		1059	add $grp aio_rmdir $path, sub {
		1060	$grp->result ($_[0]);
		1061	};
		1062	};
		1063
		1064	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1065	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1066
		1067	add $grp $dirgrp;
		1068	};
		1069
		1070	$grp
		1071	}
		1072
		1073	=item aio_sync $callback->($status)
		1074
		1075	Asynchronously call sync and call the callback when finished.
		1076
534	=item aio_fsync $fh, $callback->($status)	1077	=item aio_fsync $fh, $callback->($status)
535		1078
536	Asynchronously call fsync on the given filehandle and call the callback	1079	Asynchronously call fsync on the given filehandle and call the callback
537	with the fsync result code.	1080	with the fsync result code.
538		1081
…		…
542	callback with the fdatasync result code.	1085	callback with the fdatasync result code.
543		1086
544	If this call isn't available because your OS lacks it or it couldn't be	1087	If this call isn't available because your OS lacks it or it couldn't be
545	detected, it will be emulated by calling C<fsync> instead.	1088	detected, it will be emulated by calling C<fsync> instead.
546		1089
		1090	=item aio_syncfs $fh, $callback->($status)
		1091
		1092	Asynchronously call the syncfs syscall to sync the filesystem associated
		1093	to the given filehandle and call the callback with the syncfs result
		1094	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1095	errno to C<ENOSYS> nevertheless.
		1096
		1097	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1098
		1099	Sync the data portion of the file specified by C<$offset> and C<$length>
		1100	to disk (but NOT the metadata), by calling the Linux-specific
		1101	sync_file_range call. If sync_file_range is not available or it returns
		1102	ENOSYS, then fdatasync or fsync is being substituted.
		1103
		1104	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1105	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1106	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1107	manpage for details.
		1108
		1109	=item aio_pathsync $path, $callback->($status)
		1110
		1111	This request tries to open, fsync and close the given path. This is a
		1112	composite request intended to sync directories after directory operations
		1113	(E.g. rename). This might not work on all operating systems or have any
		1114	specific effect, but usually it makes sure that directory changes get
		1115	written to disc. It works for anything that can be opened for read-only,
		1116	not just directories.
		1117
		1118	Future versions of this function might fall back to other methods when
		1119	C<fsync> on the directory fails (such as calling C<sync>).
		1120
		1121	Passes C<0> when everything went ok, and C<-1> on error.
		1122
		1123	=cut
		1124
		1125	sub aio_pathsync($;$) {
		1126	my ($path, $cb) = @_;
		1127
		1128	my $pri = aioreq_pri;
		1129	my $grp = aio_group $cb;
		1130
		1131	aioreq_pri $pri;
		1132	add $grp aio_open $path, O_RDONLY, 0, sub {
		1133	my ($fh) = @_;
		1134	if ($fh) {
		1135	aioreq_pri $pri;
		1136	add $grp aio_fsync $fh, sub {
		1137	$grp->result ($_[0]);
		1138
		1139	aioreq_pri $pri;
		1140	add $grp aio_close $fh;
		1141	};
		1142	} else {
		1143	$grp->result (-1);
		1144	}
		1145	};
		1146
		1147	$grp
		1148	}
		1149
		1150	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1151
		1152	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1153	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1154	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1155	scalar must only be modified in-place while an aio operation is pending on
		1156	it).
		1157
		1158	It calls the C<msync> function of your OS, if available, with the memory
		1159	area starting at C<$offset> in the string and ending C<$length> bytes
		1160	later. If C<$length> is negative, counts from the end, and if C<$length>
		1161	is C<undef>, then it goes till the end of the string. The flags can be
		1162	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1163	C<IO::AIO::MS_SYNC>.
		1164
		1165	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1166
		1167	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1168	scalars.
		1169
		1170	It touches (reads or writes) all memory pages in the specified
		1171	range inside the scalar. All caveats and parameters are the same
		1172	as for C<aio_msync>, above, except for flags, which must be either
		1173	C<0> (which reads all pages and ensures they are instantiated) or
		1174	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1175	writing an octet from it, which dirties the page).
		1176
		1177	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1178
		1179	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1180	scalars.
		1181
		1182	It reads in all the pages of the underlying storage into memory (if any)
		1183	and locks them, so they are not getting swapped/paged out or removed.
		1184
		1185	If C<$length> is undefined, then the scalar will be locked till the end.
		1186
		1187	On systems that do not implement C<mlock>, this function returns C<-1>
		1188	and sets errno to C<ENOSYS>.
		1189
		1190	Note that the corresponding C<munlock> is synchronous and is
		1191	documented under L<MISCELLANEOUS FUNCTIONS>.
		1192
		1193	Example: open a file, mmap and mlock it - both will be undone when
		1194	C<$data> gets destroyed.
		1195
		1196	open my $fh, "<", $path or die "$path: $!";
		1197	my $data;
		1198	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1199	aio_mlock $data; # mlock in background
		1200
		1201	=item aio_mlockall $flags, $callback->($status)
		1202
		1203	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1204	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1205
		1206	On systems that do not implement C<mlockall>, this function returns C<-1>
		1207	and sets errno to C<ENOSYS>.
		1208
		1209	Note that the corresponding C<munlockall> is synchronous and is
		1210	documented under L<MISCELLANEOUS FUNCTIONS>.
		1211
		1212	Example: asynchronously lock all current and future pages into memory.
		1213
		1214	aio_mlockall IO::AIO::MCL_FUTURE;
		1215
547	=item aio_group $callback->(...)	1216	=item aio_group $callback->(...)
548
549	[EXPERIMENTAL]
550		1217
551	This is a very special aio request: Instead of doing something, it is a	1218	This is a very special aio request: Instead of doing something, it is a
552	container for other aio requests, which is useful if you want to bundle	1219	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	1220	many requests into a single, composite, request with a definite callback
		1221	and the ability to cancel the whole request with its subrequests.
554		1222
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1223	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	1224	for more info.
557		1225
558	Example:	1226	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	1245	phase and still requires a worker thread. Thus, the callback will not
578	be executed immediately but only after other requests in the queue have	1246	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	1247	entered their execution phase. This can be used to measure request
580	latency.	1248	latency.
581		1249
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1250	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
583		1251
584	Mainly used for debugging and benchmarking, this aio request puts one of	1252	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	1253	the request workers to sleep for the given time.
586		1254
587	While it is theoretically handy to have simple I/O scheduling requests	1255	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	1256	like sleep and file handle readable/writable, the overhead this creates is
589	is immense, so do not use this function except to put your application	1257	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	1258	except to put your application under artificial I/O pressure.
591		1259
592	=back	1260	=back
593		1261
594	=head2 IO::AIO::REQ CLASS	1262	=head2 IO::AIO::REQ CLASS
595		1263
596	All non-aggregate C<aio_*> functions return an object of this class when	1264	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	1265	called in non-void context.
598
599	A request always moves through the following five states in its lifetime,
600	in order: B<ready> (request has been created, but has not been executed
601	yet), B<execute> (request is currently being executed), B<pending>
602	(request has been executed but callback has not been called yet),
603	B<result> (results are being processed synchronously, includes calling the
604	callback) and B<done> (request has reached the end of its lifetime and
605	holds no resources anymore).
606		1266
607	=over 4	1267	=over 4
608		1268
609	=item cancel $req	1269	=item cancel $req
610		1270
611	Cancels the request, if possible. Has the effect of skipping execution	1271	Cancels the request, if possible. Has the effect of skipping execution
612	when entering the B<execute> state and skipping calling the callback when	1272	when entering the B<execute> state and skipping calling the callback when
613	entering the the B<result> state, but will leave the request otherwise	1273	entering the the B<result> state, but will leave the request otherwise
614	untouched. That means that requests that currently execute will not be	1274	untouched (with the exception of readdir). That means that requests that
615	stopped and resources held by the request will not be freed prematurely.	1275	currently execute will not be stopped and resources held by the request
		1276	will not be freed prematurely.
616		1277
617	=item cb $req $callback->(...)	1278	=item cb $req $callback->(...)
618		1279
619	Replace (or simply set) the callback registered to the request.	1280	Replace (or simply set) the callback registered to the request.
620		1281
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	1325	=item * They can also can also be added to other IO::AIO::GRP objects.
665		1326
666	=item * You must not add requests to a group from within the group callback (or	1327	=item * You must not add requests to a group from within the group callback (or
667	any later time).	1328	any later time).
668		1329
669	=item * This does not harmonise well with C<max_outstanding>, so best do
670	not combine C<aio_group> with it. Groups and feeders are recommended for
671	this kind of concurrency-limiting.
672
673	=back	1330	=back
674		1331
675	Their lifetime, simplified, looks like this: when they are empty, they	1332	Their lifetime, simplified, looks like this: when they are empty, they
676	will finish very quickly. If they contain only requests that are in the	1333	will finish very quickly. If they contain only requests that are in the
677	C<done> state, they will also finish. Otherwise they will continue to	1334	C<done> state, they will also finish. Otherwise they will continue to
678	exist.	1335	exist.
679		1336
680	That means after creating a group you have some time to add requests. And	1337	That means after creating a group you have some time to add requests
681	in the callbacks of those requests, you can add further requests to the	1338	(precisely before the callback has been invoked, which is only done within
682	group. And only when all those requests have finished will the the group	1339	the C<poll_cb>). And in the callbacks of those requests, you can add
683	itself finish.	1340	further requests to the group. And only when all those requests have
		1341	finished will the the group itself finish.
684		1342
685	=over 4	1343	=over 4
686		1344
687	=item add $grp ...	1345	=item add $grp ...
688		1346
…		…
692	be added, including other groups, as long as you do not create circular	1350	be added, including other groups, as long as you do not create circular
693	dependencies.	1351	dependencies.
694		1352
695	Returns all its arguments.	1353	Returns all its arguments.
696		1354
		1355	=item $grp->cancel_subs
		1356
		1357	Cancel all subrequests and clears any feeder, but not the group request
		1358	itself. Useful when you queued a lot of events but got a result early.
		1359
		1360	The group request will finish normally (you cannot add requests to the
		1361	group).
		1362
697	=item $grp->result (...)	1363	=item $grp->result (...)
698		1364
699	Set the result value(s) that will be passed to the group callback when all	1365	Set the result value(s) that will be passed to the group callback when all
700	subrequests have finished. By default, no argument will be passed.	1366	subrequests have finished and set the groups errno to the current value
		1367	of errno (just like calling C<errno> without an error number). By default,
		1368	no argument will be passed and errno is zero.
		1369
		1370	=item $grp->errno ([$errno])
		1371
		1372	Sets the group errno value to C<$errno>, or the current value of errno
		1373	when the argument is missing.
		1374
		1375	Every aio request has an associated errno value that is restored when
		1376	the callback is invoked. This method lets you change this value from its
		1377	default (0).
		1378
		1379	Calling C<result> will also set errno, so make sure you either set C<$!>
		1380	before the call to C<result>, or call c<errno> after it.
701		1381
702	=item feed $grp $callback->($grp)	1382	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		1383
706	Sets a feeder/generator on this group: every group can have an attached	1384	Sets a feeder/generator on this group: every group can have an attached
707	generator that generates requests if idle. The idea behind this is that,	1385	generator that generates requests if idle. The idea behind this is that,
708	although you could just queue as many requests as you want in a group,	1386	although you could just queue as many requests as you want in a group,
709	this might starve other requests for a potentially long time. For	1387	this might starve other requests for a potentially long time. For example,
710	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1388	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
711	requests, delaying any later requests for a long time.	1389	delaying any later requests for a long time.
712		1390
713	To avoid this, and allow incremental generation of requests, you can	1391	To avoid this, and allow incremental generation of requests, you can
714	instead a group and set a feeder on it that generates those requests. The	1392	instead a group and set a feeder on it that generates those requests. The
715	feed callback will be called whenever there are few enough (see C<limit>,	1393	feed callback will be called whenever there are few enough (see C<limit>,
716	below) requests active in the group itself and is expected to queue more	1394	below) requests active in the group itself and is expected to queue more
…		…
720	not impose any limits).	1398	not impose any limits).
721		1399
722	If the feed does not queue more requests when called, it will be	1400	If the feed does not queue more requests when called, it will be
723	automatically removed from the group.	1401	automatically removed from the group.
724		1402
725	If the feed limit is C<0>, it will be set to C<2> automatically.	1403	If the feed limit is C<0> when this method is called, it will be set to
		1404	C<2> automatically.
726		1405
727	Example:	1406	Example:
728		1407
729	# stat all files in @files, but only ever use four aio requests concurrently:	1408	# stat all files in @files, but only ever use four aio requests concurrently:
730		1409
…		…
742	Sets the feeder limit for the group: The feeder will be called whenever	1421	Sets the feeder limit for the group: The feeder will be called whenever
743	the group contains less than this many requests.	1422	the group contains less than this many requests.
744		1423
745	Setting the limit to C<0> will pause the feeding process.	1424	Setting the limit to C<0> will pause the feeding process.
746		1425
		1426	The default value for the limit is C<0>, but note that setting a feeder
		1427	automatically bumps it up to C<2>.
		1428
747	=back	1429	=back
748		1430
749	=head2 SUPPORT FUNCTIONS	1431	=head2 SUPPORT FUNCTIONS
750		1432
		1433	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1434
751	=over 4	1435	=over 4
752		1436
753	=item $fileno = IO::AIO::poll_fileno	1437	=item $fileno = IO::AIO::poll_fileno
754		1438
755	Return the I<request result pipe file descriptor>. This filehandle must be	1439	Return the I<request result pipe file descriptor>. This filehandle must be
756	polled for reading by some mechanism outside this module (e.g. Event or	1440	polled for reading by some mechanism outside this module (e.g. EV, Glib,
757	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1441	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
758	to call C<poll_cb> to check the results.	1442	you have to call C<poll_cb> to check the results.
759		1443
760	See C<poll_cb> for an example.	1444	See C<poll_cb> for an example.
761		1445
762	=item IO::AIO::poll_cb	1446	=item IO::AIO::poll_cb
763		1447
764	Process all outstanding events on the result pipe. You have to call this	1448	Process some outstanding events on the result pipe. You have to call
765	regularly. Returns the number of events processed. Returns immediately	1449	this regularly. Returns C<0> if all events could be processed (or there
766	when no events are outstanding.	1450	were no events to process), or C<-1> if it returned earlier for whatever
		1451	reason. Returns immediately when no events are outstanding. The amount of
		1452	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1453	C<IO::AIO::max_poll_time>.
		1454
		1455	If not all requests were processed for whatever reason, the filehandle
		1456	will still be ready when C<poll_cb> returns, so normally you don't have to
		1457	do anything special to have it called later.
		1458
		1459	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1460	ready, it can be beneficial to call this function from loops which submit
		1461	a lot of requests, to make sure the results get processed when they become
		1462	available and not just when the loop is finished and the event loop takes
		1463	over again. This function returns very fast when there are no outstanding
		1464	requests.
767		1465
768	Example: Install an Event watcher that automatically calls	1466	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	1467	IO::AIO::poll_cb with high priority (more examples can be found in the
		1468	SYNOPSIS section, at the top of this document):
770		1469
771	Event->io (fd => IO::AIO::poll_fileno,	1470	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	1471	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	1472	cb => \&IO::AIO::poll_cb);
774		1473
775	=item IO::AIO::poll_wait	1474	=item IO::AIO::poll_wait
776		1475
		1476	If there are any outstanding requests and none of them in the result
777	Wait till the result filehandle becomes ready for reading (simply does a	1477	phase, wait till the result filehandle becomes ready for reading (simply
778	C<select> on the filehandle. This is useful if you want to synchronously wait	1478	does a C<select> on the filehandle. This is useful if you want to
779	for some requests to finish).	1479	synchronously wait for some requests to finish).
780		1480
781	See C<nreqs> for an example.	1481	See C<nreqs> for an example.
782		1482
		1483	=item IO::AIO::poll
		1484
		1485	Waits until some requests have been handled.
		1486
		1487	Returns the number of requests processed, but is otherwise strictly
		1488	equivalent to:
		1489
		1490	IO::AIO::poll_wait, IO::AIO::poll_cb
		1491
783	=item IO::AIO::nreqs	1492	=item IO::AIO::flush
784		1493
785	Returns the number of requests currently outstanding (i.e. for which their	1494	Wait till all outstanding AIO requests have been handled.
786	callback has not been invoked yet).
787		1495
788	Example: wait till there are no outstanding requests anymore:	1496	Strictly equivalent to:
789		1497
790	IO::AIO::poll_wait, IO::AIO::poll_cb	1498	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	1499	while IO::AIO::nreqs;
792		1500
793	=item IO::AIO::flush	1501	=item IO::AIO::max_poll_reqs $nreqs
794		1502
795	Wait till all outstanding AIO requests have been handled.	1503	=item IO::AIO::max_poll_time $seconds
796		1504
797	Strictly equivalent to:	1505	These set the maximum number of requests (default C<0>, meaning infinity)
		1506	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1507	the maximum amount of time (default C<0>, meaning infinity) spent in
		1508	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1509	of time C<poll_cb> is allowed to use).
798		1510
799	IO::AIO::poll_wait, IO::AIO::poll_cb	1511	Setting C<max_poll_time> to a non-zero value creates an overhead of one
800	while IO::AIO::nreqs;	1512	syscall per request processed, which is not normally a problem unless your
		1513	callbacks are really really fast or your OS is really really slow (I am
		1514	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
801		1515
802	=item IO::AIO::poll	1516	Setting these is useful if you want to ensure some level of
		1517	interactiveness when perl is not fast enough to process all requests in
		1518	time.
803		1519
804	Waits until some requests have been handled.	1520	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
805		1521
806	Strictly equivalent to:	1522	Example: Install an Event watcher that automatically calls
		1523	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1524	program get the CPU sometimes even under high AIO load.
807		1525
808	IO::AIO::poll_wait, IO::AIO::poll_cb	1526	# try not to spend much more than 0.1s in poll_cb
809	if IO::AIO::nreqs;	1527	IO::AIO::max_poll_time 0.1;
		1528
		1529	# use a low priority so other tasks have priority
		1530	Event->io (fd => IO::AIO::poll_fileno,
		1531	poll => 'r', nice => 1,
		1532	cb => &IO::AIO::poll_cb);
		1533
		1534	=back
		1535
		1536	=head3 CONTROLLING THE NUMBER OF THREADS
		1537
		1538	=over
810		1539
811	=item IO::AIO::min_parallel $nthreads	1540	=item IO::AIO::min_parallel $nthreads
812		1541
813	Set the minimum number of AIO threads to C<$nthreads>. The current	1542	Set the minimum number of AIO threads to C<$nthreads>. The current
814	default is C<8>, which means eight asynchronous operations can execute	1543	default is C<8>, which means eight asynchronous operations can execute
815	concurrently at any one time (the number of outstanding requests,	1544	concurrently at any one time (the number of outstanding requests,
816	however, is unlimited).	1545	however, is unlimited).
817		1546
818	IO::AIO starts threads only on demand, when an AIO request is queued and	1547	IO::AIO starts threads only on demand, when an AIO request is queued and
819	no free thread exists.	1548	no free thread exists. Please note that queueing up a hundred requests can
		1549	create demand for a hundred threads, even if it turns out that everything
		1550	is in the cache and could have been processed faster by a single thread.
820		1551
821	It is recommended to keep the number of threads relatively low, as some	1552	It is recommended to keep the number of threads relatively low, as some
822	Linux kernel versions will scale negatively with the number of threads	1553	Linux kernel versions will scale negatively with the number of threads
823	(higher parallelity => MUCH higher latency). With current Linux 2.6	1554	(higher parallelity => MUCH higher latency). With current Linux 2.6
824	versions, 4-32 threads should be fine.	1555	versions, 4-32 threads should be fine.
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	1569	This module automatically runs C<max_parallel 0> at program end, to ensure
839	that all threads are killed and that there are no outstanding requests.	1570	that all threads are killed and that there are no outstanding requests.
840		1571
841	Under normal circumstances you don't need to call this function.	1572	Under normal circumstances you don't need to call this function.
842		1573
		1574	=item IO::AIO::max_idle $nthreads
		1575
		1576	Limit the number of threads (default: 4) that are allowed to idle
		1577	(i.e., threads that did not get a request to process within the idle
		1578	timeout (default: 10 seconds). That means if a thread becomes idle while
		1579	C<$nthreads> other threads are also idle, it will free its resources and
		1580	exit.
		1581
		1582	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1583	to allow for extremely high load situations, but want to free resources
		1584	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1585
		1586	The default is probably ok in most situations, especially if thread
		1587	creation is fast. If thread creation is very slow on your system you might
		1588	want to use larger values.
		1589
		1590	=item IO::AIO::idle_timeout $seconds
		1591
		1592	Sets the minimum idle timeout (default 10) after which worker threads are
		1593	allowed to exit. SEe C<IO::AIO::max_idle>.
		1594
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1595	=item IO::AIO::max_outstanding $maxreqs
844		1596
845	[DEPRECATED]
846
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1597	Sets the maximum number of outstanding requests to C<$nreqs>. If
848	try to queue up more than this number of requests, the caller will block until	1598	you do queue up more than this number of requests, the next call to
849	some requests have been handled.	1599	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1600	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1601	longer exceeded.
850		1602
851	The default is very large, so normally there is no practical limit. If you	1603	In other words, this setting does not enforce a queue limit, but can be
852	queue up many requests in a loop it often improves speed if you set	1604	used to make poll functions block if the limit is exceeded.
853	this to a relatively low number, such as C<100>.
854		1605
855	This function does not work well together with C<aio_group>'s, and their	1606	This is a very bad function to use in interactive programs because it
856	feeder interface is better suited to limiting concurrency, so do not use	1607	blocks, and a bad way to reduce concurrency because it is inexact: Better
857	this function.	1608	use an C<aio_group> together with a feed callback.
858		1609
859	Under normal circumstances you don't need to call this function.	1610	It's main use is in scripts without an event loop - when you want to stat
		1611	a lot of files, you can write somehting like this:
		1612
		1613	IO::AIO::max_outstanding 32;
		1614
		1615	for my $path (...) {
		1616	aio_stat $path , ...;
		1617	IO::AIO::poll_cb;
		1618	}
		1619
		1620	IO::AIO::flush;
		1621
		1622	The call to C<poll_cb> inside the loop will normally return instantly, but
		1623	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1624	some requests have been handled. This keeps the loop from pushing a large
		1625	number of C<aio_stat> requests onto the queue.
		1626
		1627	The default value for C<max_outstanding> is very large, so there is no
		1628	practical limit on the number of outstanding requests.
860		1629
861	=back	1630	=back
862		1631
		1632	=head3 STATISTICAL INFORMATION
		1633
		1634	=over
		1635
		1636	=item IO::AIO::nreqs
		1637
		1638	Returns the number of requests currently in the ready, execute or pending
		1639	states (i.e. for which their callback has not been invoked yet).
		1640
		1641	Example: wait till there are no outstanding requests anymore:
		1642
		1643	IO::AIO::poll_wait, IO::AIO::poll_cb
		1644	while IO::AIO::nreqs;
		1645
		1646	=item IO::AIO::nready
		1647
		1648	Returns the number of requests currently in the ready state (not yet
		1649	executed).
		1650
		1651	=item IO::AIO::npending
		1652
		1653	Returns the number of requests currently in the pending state (executed,
		1654	but not yet processed by poll_cb).
		1655
		1656	=back
		1657
		1658	=head3 MISCELLANEOUS FUNCTIONS
		1659
		1660	IO::AIO implements some functions that might be useful, but are not
		1661	asynchronous.
		1662
		1663	=over 4
		1664
		1665	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1666
		1667	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1668	but is blocking (this makes most sense if you know the input data is
		1669	likely cached already and the output filehandle is set to non-blocking
		1670	operations).
		1671
		1672	Returns the number of bytes copied, or C<-1> on error.
		1673
		1674	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1675
		1676	Simply calls the C<posix_fadvise> function (see its
		1677	manpage for details). The following advice constants are
		1678	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1679	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1680	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1681
		1682	On systems that do not implement C<posix_fadvise>, this function returns
		1683	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1684
		1685	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1686
		1687	Simply calls the C<posix_madvise> function (see its
		1688	manpage for details). The following advice constants are
		1689	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1690	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1691
		1692	On systems that do not implement C<posix_madvise>, this function returns
		1693	ENOSYS, otherwise the return value of C<posix_madvise>.
		1694
		1695	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1696
		1697	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1698	$scalar (see its manpage for details). The following protect
		1699	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1700	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1701
		1702	On systems that do not implement C<mprotect>, this function returns
		1703	ENOSYS, otherwise the return value of C<mprotect>.
		1704
		1705	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1706
		1707	Memory-maps a file (or anonymous memory range) and attaches it to the
		1708	given C<$scalar>, which will act like a string scalar.
		1709
		1710	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1711	change the string length, and most read-only operations such as copying it
		1712	or searching it with regexes and so on.
		1713
		1714	Anything else is unsafe and will, at best, result in memory leaks.
		1715
		1716	The memory map associated with the C<$scalar> is automatically removed
		1717	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1718	C<IO::AIO::munmap> functions are called.
		1719
		1720	This calls the C<mmap>(2) function internally. See your system's manual
		1721	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1722
		1723	The C<$length> must be larger than zero and smaller than the actual
		1724	filesize.
		1725
		1726	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1727	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1728
		1729	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1730	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1731	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1732	(which is set to C<MAP_ANON> if your system only provides this
		1733	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1734	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1735	C<IO::AIO::MAP_NONBLOCK>
		1736
		1737	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1738
		1739	C<$offset> is the offset from the start of the file - it generally must be
		1740	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1741
		1742	Example:
		1743
		1744	use Digest::MD5;
		1745	use IO::AIO;
		1746
		1747	open my $fh, "<verybigfile"
		1748	or die "$!";
		1749
		1750	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1751	or die "verybigfile: $!";
		1752
		1753	my $fast_md5 = md5 $data;
		1754
		1755	=item IO::AIO::munmap $scalar
		1756
		1757	Removes a previous mmap and undefines the C<$scalar>.
		1758
		1759	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1760
		1761	Calls the C<munlock> function, undoing the effects of a previous
		1762	C<aio_mlock> call (see its description for details).
		1763
		1764	=item IO::AIO::munlockall
		1765
		1766	Calls the C<munlockall> function.
		1767
		1768	On systems that do not implement C<munlockall>, this function returns
		1769	ENOSYS, otherwise the return value of C<munlockall>.
		1770
		1771	=back
		1772
863	=cut	1773	=cut
864		1774
865	# support function to convert a fd into a perl filehandle
866	sub _fd2fh {
867	return undef if $_[0] < 0;
868
869	# try to generate nice filehandles
870	my $sym = "IO::AIO::fd#$_[0]";
871	local *$sym;
872
873	open *$sym, "+<&=$_[0]" # usually works under any unix
874	or open *$sym, "<&=$_[0]" # cygwin needs this
875	or open *$sym, ">&=$_[0]" # or this
876	or return undef;
877
878	*$sym
879	}
880
881	min_parallel 8;	1775	min_parallel 8;
882		1776
883	END {	1777	END { flush }
884	max_parallel 0;
885	}
886		1778
887	1;	1779	1;
888		1780
		1781	=head1 EVENT LOOP INTEGRATION
		1782
		1783	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1784	automatically into many event loops:
		1785
		1786	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1787	use AnyEvent::AIO;
		1788
		1789	You can also integrate IO::AIO manually into many event loops, here are
		1790	some examples of how to do this:
		1791
		1792	# EV integration
		1793	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1794
		1795	# Event integration
		1796	Event->io (fd => IO::AIO::poll_fileno,
		1797	poll => 'r',
		1798	cb => \&IO::AIO::poll_cb);
		1799
		1800	# Glib/Gtk2 integration
		1801	add_watch Glib::IO IO::AIO::poll_fileno,
		1802	in => sub { IO::AIO::poll_cb; 1 };
		1803
		1804	# Tk integration
		1805	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1806	readable => \&IO::AIO::poll_cb);
		1807
		1808	# Danga::Socket integration
		1809	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1810	\&IO::AIO::poll_cb);
		1811
889	=head2 FORK BEHAVIOUR	1812	=head2 FORK BEHAVIOUR
890		1813
891	This module should do "the right thing" when the process using it forks:	1814	Usage of pthreads in a program changes the semantics of fork
		1815	considerably. Specifically, only async-safe functions can be called after
		1816	fork. Perl doesn't know about this, so in general, you cannot call fork
		1817	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		1818	pthreads, so this applies, but many other extensions and (for inexplicable
		1819	reasons) perl itself often is linked against pthreads, so this limitation
		1820	applies to quite a lot of perls.
892		1821
893	Before the fork, IO::AIO enters a quiescent state where no requests	1822	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
894	can be added in other threads and no results will be processed. After	1823	only works in the process that loaded it. Forking is fully supported, but
895	the fork the parent simply leaves the quiescent state and continues	1824	using IO::AIO in the child is not.
896	request/result processing, while the child clears the request/result
897	queue (so the requests started before the fork will only be handled in
898	the parent). Threads will be started on demand until the limit ste in the
899	parent process has been reached again.
900		1825
901	In short: the parent will, after a short pause, continue as if fork had	1826	You might get around by not I<using> IO::AIO before (or after)
902	not been called, while the child will act as if IO::AIO has not been used	1827	forking. You could also try to call the L<IO::AIO::reinit> function in the
903	yet.	1828	child:
		1829
		1830	=over 4
		1831
		1832	=item IO::AIO::reinit
		1833
		1834	Abandons all current requests and I/O threads and simply reinitialises all
		1835	data structures. This is not an operation supported by any standards, but
		1836	happens to work on GNU/Linux and some newer BSD systems.
		1837
		1838	The only reasonable use for this function is to call it after forking, if
		1839	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		1840	the process will result in undefined behaviour. Calling it at any time
		1841	will also result in any undefined (by POSIX) behaviour.
		1842
		1843	=back
904		1844
905	=head2 MEMORY USAGE	1845	=head2 MEMORY USAGE
906		1846
		1847	Per-request usage:
		1848
907	Each aio request uses - depending on your architecture - around 128 bytes	1849	Each aio request uses - depending on your architecture - around 100-200
908	of memory. In addition, stat requests need a stat buffer (possibly a few	1850	bytes of memory. In addition, stat requests need a stat buffer (possibly
909	hundred bytes). Perl scalars and other data passed into aio requests will	1851	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1852	scalars and other data passed into aio requests will also be locked and
		1853	will consume memory till the request has entered the done state.
911		1854
912	This is now awfully much, so queuing lots of requests is not usually a	1855	This is not awfully much, so queuing lots of requests is not usually a
913	problem.	1856	problem.
914		1857
915	Each thread needs a stack area which is usually around 16k, sometimes much	1858	Per-thread usage:
916	larger, depending on the OS.	1859
		1860	In the execution phase, some aio requests require more memory for
		1861	temporary buffers, and each thread requires a stack and other data
		1862	structures (usually around 16k-128k, depending on the OS).
		1863
		1864	=head1 KNOWN BUGS
		1865
		1866	Known bugs will be fixed in the next release.
917		1867
918	=head1 SEE ALSO	1868	=head1 SEE ALSO
919		1869
920	L<Coro::AIO>.	1870	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1871	more natural syntax.
921		1872
922	=head1 AUTHOR	1873	=head1 AUTHOR
923		1874
924	Marc Lehmann <schmorp@schmorp.de>	1875	Marc Lehmann <schmorp@schmorp.de>
925	http://home.schmorp.de/	1876	http://home.schmorp.de/

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