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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs.
Revision 1.107 by root, Fri Jun 1 05:52:59 2007 UTC

…		…
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", 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
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	17	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	18	$_[0] > 0 or die "read error: $!";
18	};	19	};
19		20
20	use IO::AIO 2; # version has aio objects	21	# version 2+ has request and group objects
		22	use IO::AIO 2;
21		23
		24	aioreq_pri 4; # give next request a very high priority
22	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
23	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
24		27
25	# AnyEvent	28	my $grp = aio_group sub { print "all stats done\n" };
		29	add $grp aio_stat "..." for ...;
		30
		31	# AnyEvent integration
26	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
27	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });	33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
28		34
29	# Event	35	# Event integration
30	Event->io (fd => IO::AIO::poll_fileno,	36	Event->io (fd => IO::AIO::poll_fileno,
31	poll => 'r',	37	poll => 'r',
32	cb => \&IO::AIO::poll_cb);	38	cb => \&IO::AIO::poll_cb);
33		39
34	# Glib/Gtk2	40	# Glib/Gtk2 integration
35	add_watch Glib::IO IO::AIO::poll_fileno,	41	add_watch Glib::IO IO::AIO::poll_fileno,
36	in => sub { IO::AIO::poll_cb; 1 };	42	in => sub { IO::AIO::poll_cb; 1 };
37		43
38	# Tk	44	# Tk integration
39	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
40	readable => \&IO::AIO::poll_cb);	46	readable => \&IO::AIO::poll_cb);
41		47
42	# Danga::Socket	48	# Danga::Socket integration
43	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
44	\&IO::AIO::poll_cb);	50	\&IO::AIO::poll_cb);
45		51
46
47	=head1 DESCRIPTION	52	=head1 DESCRIPTION
48		53
49	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
50	operating system supports.	55	operating system supports.
51		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for example
		68	sockets), using these functions on file descriptors that support
		69	nonblocking operation (again, sockets, pipes etc.) is very inefficient or
		70	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
		71	for that (such as the L<Event\|Event> module): IO::AIO will naturally fit
		72	into such an event loop itself.
		73
52	Currently, a number of threads are started that execute your read/writes	74	In this version, a number of threads are started that execute your
53	and signal their completion. You don't need thread support in your libc or	75	requests and signal their completion. You don't need thread support
54	perl, and the threads created by this module will not be visible to the	76	in perl, and the threads created by this module will not be visible
55	pthreads library. In the future, this module might make use of the native	77	to perl. In the future, this module might make use of the native aio
56	aio functions available on many operating systems. However, they are often	78	functions available on many operating systems. However, they are often
57	not well-supported (Linux doesn't allow them on normal files currently,	79	not well-supported or restricted (GNU/Linux doesn't allow them on normal
58	for example), and they would only support aio_read and aio_write, so the	80	files currently, for example), and they would only support aio_read and
59	remaining functionality would have to be implemented using threads anyway.	81	aio_write, so the remaining functionality would have to be implemented
		82	using threads anyway.
60		83
61	Although the module will work with in the presence of other threads, it is	84	Although the module will work with in the presence of other (Perl-)
62	currently not reentrant, so use appropriate locking yourself, always call	85	threads, it is currently not reentrant in any way, so use appropriate
63	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	86	locking yourself, always call C<poll_cb> from within the same thread, or
64	C<aio_> functions) recursively.	87	never call C<poll_cb> (or other C<aio_> functions) recursively.
		88
		89	=head2 EXAMPLE
		90
		91	This is a simple example that uses the Event module and loads
		92	F</etc/passwd> asynchronously:
		93
		94	use Fcntl;
		95	use Event;
		96	use IO::AIO;
		97
		98	# register the IO::AIO callback with Event
		99	Event->io (fd => IO::AIO::poll_fileno,
		100	poll => 'r',
		101	cb => \&IO::AIO::poll_cb);
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	Event::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	Event::loop;
		132
		133	=head1 REQUEST ANATOMY AND LIFETIME
		134
		135	Every C<aio_*> function creates a request. which is a C data structure not
		136	directly visible to Perl.
		137
		138	If called in non-void context, every request function returns a Perl
		139	object representing the request. In void context, nothing is returned,
		140	which saves a bit of memory.
		141
		142	The perl object is a fairly standard ref-to-hash object. The hash contents
		143	are not used by IO::AIO so you are free to store anything you like in it.
		144
		145	During their existance, aio requests travel through the following states,
		146	in order:
		147
		148	=over 4
		149
		150	=item ready
		151
		152	Immediately after a request is created it is put into the ready state,
		153	waiting for a thread to execute it.
		154
		155	=item execute
		156
		157	A thread has accepted the request for processing and is currently
		158	executing it (e.g. blocking in read).
		159
		160	=item pending
		161
		162	The request has been executed and is waiting for result processing.
		163
		164	While request submission and execution is fully asynchronous, result
		165	processing is not and relies on the perl interpreter calling C<poll_cb>
		166	(or another function with the same effect).
		167
		168	=item result
		169
		170	The request results are processed synchronously by C<poll_cb>.
		171
		172	The C<poll_cb> function will process all outstanding aio requests by
		173	calling their callbacks, freeing memory associated with them and managing
		174	any groups they are contained in.
		175
		176	=item done
		177
		178	Request has reached the end of its lifetime and holds no resources anymore
		179	(except possibly for the Perl object, but its connection to the actual
		180	aio request is severed and calling its methods will either do nothing or
		181	result in a runtime error).
		182
		183	=back
65		184
66	=cut	185	=cut
67		186
68	package IO::AIO;	187	package IO::AIO;
69		188
…		…
71	use strict 'vars';	190	use strict 'vars';
72		191
73	use base 'Exporter';	192	use base 'Exporter';
74		193
75	BEGIN {	194	BEGIN {
76	our $VERSION = '1.99';	195	our $VERSION = '2.4';
77		196
78	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	197	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
79	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	198	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
80	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	199	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
81	aio_group);	200	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
82	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	201	aio_chown aio_chmod aio_utime);
		202	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
		203	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		204	min_parallel max_parallel max_idle
		205	nreqs nready npending nthreads
		206	max_poll_time max_poll_reqs);
83		207
84	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	208	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
85		209
86	require XSLoader;	210	require XSLoader;
87	XSLoader::load ("IO::AIO", $VERSION);	211	XSLoader::load ("IO::AIO", $VERSION);
88	}	212	}
89		213
90	=head1 FUNCTIONS	214	=head1 FUNCTIONS
91		215
92	=head2 AIO FUNCTIONS	216	=head2 AIO REQUEST FUNCTIONS
93		217
94	All the C<aio_*> calls are more or less thin wrappers around the syscall	218	All the C<aio_*> calls are more or less thin wrappers around the syscall
95	with the same name (sans C<aio_>). The arguments are similar or identical,	219	with the same name (sans C<aio_>). The arguments are similar or identical,
96	and they all accept an additional (and optional) C<$callback> argument	220	and they all accept an additional (and optional) C<$callback> argument
97	which must be a code reference. This code reference will get called with	221	which must be a code reference. This code reference will get called with
…		…
100	syscall has been executed asynchronously.	224	syscall has been executed asynchronously.
101		225
102	All functions expecting a filehandle keep a copy of the filehandle	226	All functions expecting a filehandle keep a copy of the filehandle
103	internally until the request has finished.	227	internally until the request has finished.
104		228
105	All non-composite requests (requests that are not broken down into
106	multiple requests) return objects of type L<IO::AIO::REQ> that allow	229	All functions return request objects of type L<IO::AIO::REQ> that allow
107	further manipulation of running requests.	230	further manipulation of those requests while they are in-flight.
108		231
109	The pathnames you pass to these routines I<must> be absolute and	232	The pathnames you pass to these routines I<must> be absolute and
110	encoded in byte form. The reason for the former is that at the time the	233	encoded as octets. The reason for the former is that at the time the
111	request is being executed, the current working directory could have	234	request is being executed, the current working directory could have
112	changed. Alternatively, you can make sure that you never change the	235	changed. Alternatively, you can make sure that you never change the
113	current working directory.	236	current working directory anywhere in the program and then use relative
		237	paths.
114		238
115	To encode pathnames to byte form, either make sure you either: a)	239	To encode pathnames as octets, either make sure you either: a) always pass
116	always pass in filenames you got from outside (command line, readdir	240	in filenames you got from outside (command line, readdir etc.) without
117	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	241	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
118	your pathnames to the locale (or other) encoding in effect in the user	242	your pathnames to the locale (or other) encoding in effect in the user
119	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	243	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
120	use something else.	244	use something else to ensure your scalar has the correct contents.
		245
		246	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		247	handles correctly wether it is set or not.
121		248
122	=over 4	249	=over 4
		250
		251	=item $prev_pri = aioreq_pri [$pri]
		252
		253	Returns the priority value that would be used for the next request and, if
		254	C<$pri> is given, sets the priority for the next aio request.
		255
		256	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		257	and C<4>, respectively. Requests with higher priority will be serviced
		258	first.
		259
		260	The priority will be reset to C<0> after each call to one of the C<aio_*>
		261	functions.
		262
		263	Example: open a file with low priority, then read something from it with
		264	higher priority so the read request is serviced before other low priority
		265	open requests (potentially spamming the cache):
		266
		267	aioreq_pri -3;
		268	aio_open ..., sub {
		269	return unless $_[0];
		270
		271	aioreq_pri -2;
		272	aio_read $_[0], ..., sub {
		273	...
		274	};
		275	};
		276
		277
		278	=item aioreq_nice $pri_adjust
		279
		280	Similar to C<aioreq_pri>, but subtracts the given value from the current
		281	priority, so the effect is cumulative.
		282
123		283
124	=item aio_open $pathname, $flags, $mode, $callback->($fh)	284	=item aio_open $pathname, $flags, $mode, $callback->($fh)
125		285
126	Asynchronously open or create a file and call the callback with a newly	286	Asynchronously open or create a file and call the callback with a newly
127	created filehandle for the file.	287	created filehandle for the file.
…		…
133	list. They are the same as used by C<sysopen>.	293	list. They are the same as used by C<sysopen>.
134		294
135	Likewise, C<$mode> specifies the mode of the newly created file, if it	295	Likewise, C<$mode> specifies the mode of the newly created file, if it
136	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	296	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
137	except that it is mandatory (i.e. use C<0> if you don't create new files,	297	except that it is mandatory (i.e. use C<0> if you don't create new files,
138	and C<0666> or C<0777> if you do).	298	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		299	by the umask in effect then the request is being executed, so better never
		300	change the umask.
139		301
140	Example:	302	Example:
141		303
142	aio_open "/etc/passwd", O_RDONLY, 0, sub {	304	aio_open "/etc/passwd", O_RDONLY, 0, sub {
143	if ($_[0]) {	305	if ($_[0]) {
…		…
146	} else {	308	} else {
147	die "open failed: $!\n";	309	die "open failed: $!\n";
148	}	310	}
149	};	311	};
150		312
		313
151	=item aio_close $fh, $callback->($status)	314	=item aio_close $fh, $callback->($status)
152		315
153	Asynchronously close a file and call the callback with the result	316	Asynchronously close a file and call the callback with the result
154	code. I<WARNING:> although accepted, you should not pass in a perl	317	code. I<WARNING:> although accepted, you should not pass in a perl
155	filehandle here, as perl will likely close the file descriptor another	318	filehandle here, as perl will likely close the file descriptor another
…		…
157	C<close> or just let filehandles go out of scope.	320	C<close> or just let filehandles go out of scope.
158		321
159	This is supposed to be a bug in the API, so that might change. It's	322	This is supposed to be a bug in the API, so that might change. It's
160	therefore best to avoid this function.	323	therefore best to avoid this function.
161		324
		325
162	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	326	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
163		327
164	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	328	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
165		329
166	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	330	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
…		…
178	aio_read $fh, 7, 15, $buffer, 0, sub {	342	aio_read $fh, 7, 15, $buffer, 0, sub {
179	$_[0] > 0 or die "read error: $!";	343	$_[0] > 0 or die "read error: $!";
180	print "read $_[0] bytes: <$buffer>\n";	344	print "read $_[0] bytes: <$buffer>\n";
181	};	345	};
182		346
183	=item aio_move $srcpath, $dstpath, $callback->($status)
184
185	Try to move the I<file> (directories not supported as either source or
186	destination) from C<$srcpath> to C<$dstpath> and call the callback with
187	the C<0> (error) or C<-1> ok.
188
189	This is a composite request that tries to rename(2) the file first. If
190	rename files with C<EXDEV>, it creates the destination file with mode 0200
191	and copies the contents of the source file into it using C<aio_sendfile>,
192	followed by restoring atime, mtime, access mode and uid/gid, in that
193	order, and unlinking the C<$srcpath>.
194
195	If an error occurs, the partial destination file will be unlinked, if
196	possible, except when setting atime, mtime, access mode and uid/gid, where
197	errors are being ignored.
198
199	=cut
200
201	sub aio_move($$$) {
202	my ($src, $dst, $cb) = @_;
203
204	aio_rename $src, $dst, sub {
205	if ($_[0] && $! == EXDEV) {
206	aio_open $src, O_RDONLY, 0, sub {
207	if (my $src_fh = $_[0]) {
208	my @stat = stat $src_fh;
209
210	aio_open $dst, O_WRONLY, 0200, sub {
211	if (my $dst_fh = $_[0]) {
212	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
213	close $src_fh;
214
215	if ($_[0] == $stat[7]) {
216	utime $stat[8], $stat[9], $dst;
217	chmod $stat[2] & 07777, $dst_fh;
218	chown $stat[4], $stat[5], $dst_fh;
219	close $dst_fh;
220
221	aio_unlink $src, sub {
222	$cb->($_[0]);
223	};
224	} else {
225	my $errno = $!;
226	aio_unlink $dst, sub {
227	$! = $errno;
228	$cb->(-1);
229	};
230	}
231	};
232	} else {
233	$cb->(-1);
234	}
235	},
236
237	} else {
238	$cb->(-1);
239	}
240	};
241	} else {
242	$cb->($_[0]);
243	}
244	};
245	}
246		347
247	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	348	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
248		349
249	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	350	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
250	reading at byte offset C<$in_offset>, and starts writing at the current	351	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
264	C<$in_fh> than are written, and there is no way to find out how many	365	C<$in_fh> than are written, and there is no way to find out how many
265	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	366	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
266	provides the number of bytes written to C<$out_fh>. Only if the result	367	provides the number of bytes written to C<$out_fh>. Only if the result
267	value equals C<$length> one can assume that C<$length> bytes have been	368	value equals C<$length> one can assume that C<$length> bytes have been
268	read.	369	read.
		370
269		371
270	=item aio_readahead $fh,$offset,$length, $callback->($retval)	372	=item aio_readahead $fh,$offset,$length, $callback->($retval)
271		373
272	C<aio_readahead> populates the page cache with data from a file so that	374	C<aio_readahead> populates the page cache with data from a file so that
273	subsequent reads from that file will not block on disk I/O. The C<$offset>	375	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
279	file. The current file offset of the file is left unchanged.	381	file. The current file offset of the file is left unchanged.
280		382
281	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	383	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
282	emulated by simply reading the data, which would have a similar effect.	384	emulated by simply reading the data, which would have a similar effect.
283		385
		386
284	=item aio_stat $fh_or_path, $callback->($status)	387	=item aio_stat $fh_or_path, $callback->($status)
285		388
286	=item aio_lstat $fh, $callback->($status)	389	=item aio_lstat $fh, $callback->($status)
287		390
288	Works like perl's C<stat> or C<lstat> in void context. The callback will	391	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
301	aio_stat "/etc/passwd", sub {	404	aio_stat "/etc/passwd", sub {
302	$_[0] and die "stat failed: $!";	405	$_[0] and die "stat failed: $!";
303	print "size is ", -s _, "\n";	406	print "size is ", -s _, "\n";
304	};	407	};
305		408
		409
		410	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		411
		412	Works like perl's C<utime> function (including the special case of $atime
		413	and $mtime being undef). Fractional times are supported if the underlying
		414	syscalls support them.
		415
		416	When called with a pathname, uses utimes(2) if available, otherwise
		417	utime(2). If called on a file descriptor, uses futimes(2) if available,
		418	otherwise returns ENOSYS, so this is not portable.
		419
		420	Examples:
		421
		422	# set atime and mtime to current time (basically touch(1)):
		423	aio_utime "path", undef, undef;
		424	# set atime to current time and mtime to beginning of the epoch:
		425	aio_utime "path", time, undef; # undef==0
		426
		427
		428	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		429
		430	Works like perl's C<chown> function, except that C<undef> for either $uid
		431	or $gid is being interpreted as "do not change" (but -1 can also be used).
		432
		433	Examples:
		434
		435	# same as "chown root path" in the shell:
		436	aio_chown "path", 0, -1;
		437	# same as above:
		438	aio_chown "path", 0, undef;
		439
		440
		441	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		442
		443	Works like perl's C<chmod> function.
		444
		445
306	=item aio_unlink $pathname, $callback->($status)	446	=item aio_unlink $pathname, $callback->($status)
307		447
308	Asynchronously unlink (delete) a file and call the callback with the	448	Asynchronously unlink (delete) a file and call the callback with the
309	result code.	449	result code.
310		450
		451
		452	=item aio_mknod $path, $mode, $dev, $callback->($status)
		453
		454	[EXPERIMENTAL]
		455
		456	Asynchronously create a device node (or fifo). See mknod(2).
		457
		458	The only (POSIX-) portable way of calling this function is:
		459
		460	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		461
		462
311	=item aio_link $srcpath, $dstpath, $callback->($status)	463	=item aio_link $srcpath, $dstpath, $callback->($status)
312		464
313	Asynchronously create a new link to the existing object at C<$srcpath> at	465	Asynchronously create a new link to the existing object at C<$srcpath> at
314	the path C<$dstpath> and call the callback with the result code.	466	the path C<$dstpath> and call the callback with the result code.
315		467
		468
316	=item aio_symlink $srcpath, $dstpath, $callback->($status)	469	=item aio_symlink $srcpath, $dstpath, $callback->($status)
317		470
318	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	471	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
319	the path C<$dstpath> and call the callback with the result code.	472	the path C<$dstpath> and call the callback with the result code.
320		473
		474
		475	=item aio_readlink $path, $callback->($link)
		476
		477	Asynchronously read the symlink specified by C<$path> and pass it to
		478	the callback. If an error occurs, nothing or undef gets passed to the
		479	callback.
		480
		481
321	=item aio_rename $srcpath, $dstpath, $callback->($status)	482	=item aio_rename $srcpath, $dstpath, $callback->($status)
322		483
323	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	484	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
324	rename(2) and call the callback with the result code.	485	rename(2) and call the callback with the result code.
325		486
		487
		488	=item aio_mkdir $pathname, $mode, $callback->($status)
		489
		490	Asynchronously mkdir (create) a directory and call the callback with
		491	the result code. C<$mode> will be modified by the umask at the time the
		492	request is executed, so do not change your umask.
		493
		494
326	=item aio_rmdir $pathname, $callback->($status)	495	=item aio_rmdir $pathname, $callback->($status)
327		496
328	Asynchronously rmdir (delete) a directory and call the callback with the	497	Asynchronously rmdir (delete) a directory and call the callback with the
329	result code.	498	result code.
		499
330		500
331	=item aio_readdir $pathname, $callback->($entries)	501	=item aio_readdir $pathname, $callback->($entries)
332		502
333	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	503	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
334	directory (i.e. opendir + readdir + closedir). The entries will not be	504	directory (i.e. opendir + readdir + closedir). The entries will not be
335	sorted, and will B<NOT> include the C<.> and C<..> entries.	505	sorted, and will B<NOT> include the C<.> and C<..> entries.
336		506
337	The callback a single argument which is either C<undef> or an array-ref	507	The callback a single argument which is either C<undef> or an array-ref
338	with the filenames.	508	with the filenames.
339		509
		510
		511	=item aio_load $path, $data, $callback->($status)
		512
		513	This is a composite request that tries to fully load the given file into
		514	memory. Status is the same as with aio_read.
		515
		516	=cut
		517
		518	sub aio_load($$;$) {
		519	aio_block {
		520	my ($path, undef, $cb) = @_;
		521	my $data = \$_[1];
		522
		523	my $pri = aioreq_pri;
		524	my $grp = aio_group $cb;
		525
		526	aioreq_pri $pri;
		527	add $grp aio_open $path, O_RDONLY, 0, sub {
		528	my $fh = shift
		529	or return $grp->result (-1);
		530
		531	aioreq_pri $pri;
		532	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		533	$grp->result ($_[0]);
		534	};
		535	};
		536
		537	$grp
		538	}
		539	}
		540
		541	=item aio_copy $srcpath, $dstpath, $callback->($status)
		542
		543	Try to copy the I<file> (directories not supported as either source or
		544	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		545	the C<0> (error) or C<-1> ok.
		546
		547	This is a composite request that it creates the destination file with
		548	mode 0200 and copies the contents of the source file into it using
		549	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		550	uid/gid, in that order.
		551
		552	If an error occurs, the partial destination file will be unlinked, if
		553	possible, except when setting atime, mtime, access mode and uid/gid, where
		554	errors are being ignored.
		555
		556	=cut
		557
		558	sub aio_copy($$;$) {
		559	aio_block {
		560	my ($src, $dst, $cb) = @_;
		561
		562	my $pri = aioreq_pri;
		563	my $grp = aio_group $cb;
		564
		565	aioreq_pri $pri;
		566	add $grp aio_open $src, O_RDONLY, 0, sub {
		567	if (my $src_fh = $_[0]) {
		568	my @stat = stat $src_fh;
		569
		570	aioreq_pri $pri;
		571	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		572	if (my $dst_fh = $_[0]) {
		573	aioreq_pri $pri;
		574	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		575	if ($_[0] == $stat[7]) {
		576	$grp->result (0);
		577	close $src_fh;
		578
		579	# those should not normally block. should. should.
		580	utime $stat[8], $stat[9], $dst;
		581	chmod $stat[2] & 07777, $dst_fh;
		582	chown $stat[4], $stat[5], $dst_fh;
		583	close $dst_fh;
		584	} else {
		585	$grp->result (-1);
		586	close $src_fh;
		587	close $dst_fh;
		588
		589	aioreq $pri;
		590	add $grp aio_unlink $dst;
		591	}
		592	};
		593	} else {
		594	$grp->result (-1);
		595	}
		596	},
		597
		598	} else {
		599	$grp->result (-1);
		600	}
		601	};
		602
		603	$grp
		604	}
		605	}
		606
		607	=item aio_move $srcpath, $dstpath, $callback->($status)
		608
		609	Try to move the I<file> (directories not supported as either source or
		610	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		611	the C<0> (error) or C<-1> ok.
		612
		613	This is a composite request that tries to rename(2) the file first. If
		614	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		615	that is successful, unlinking the C<$srcpath>.
		616
		617	=cut
		618
		619	sub aio_move($$;$) {
		620	aio_block {
		621	my ($src, $dst, $cb) = @_;
		622
		623	my $pri = aioreq_pri;
		624	my $grp = aio_group $cb;
		625
		626	aioreq_pri $pri;
		627	add $grp aio_rename $src, $dst, sub {
		628	if ($_[0] && $! == EXDEV) {
		629	aioreq_pri $pri;
		630	add $grp aio_copy $src, $dst, sub {
		631	$grp->result ($_[0]);
		632
		633	if (!$_[0]) {
		634	aioreq_pri $pri;
		635	add $grp aio_unlink $src;
		636	}
		637	};
		638	} else {
		639	$grp->result ($_[0]);
		640	}
		641	};
		642
		643	$grp
		644	}
		645	}
		646
340	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	647	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
341		648
342	Scans a directory (similar to C<aio_readdir>) but additionally tries to	649	Scans a directory (similar to C<aio_readdir>) but additionally tries to
343	separate the entries of directory C<$path> into two sets of names, ones	650	efficiently separate the entries of directory C<$path> into two sets of
344	you can recurse into (directories or links to them), and ones you cannot	651	names, directories you can recurse into (directories), and ones you cannot
345	recurse into (everything else).	652	recurse into (everything else, including symlinks to directories).
346		653
347	C<aio_scandir> is a composite request that consists of many sub	654	C<aio_scandir> is a composite request that creates of many sub requests_
348	requests. C<$maxreq> specifies the maximum number of outstanding aio	655	C<$maxreq> specifies the maximum number of outstanding aio requests that
349	requests that this function generates. If it is C<< <= 0 >>, then a	656	this function generates. If it is C<< <= 0 >>, then a suitable default
350	suitable default will be chosen (currently 8).	657	will be chosen (currently 4).
351		658
352	On error, the callback is called without arguments, otherwise it receives	659	On error, the callback is called without arguments, otherwise it receives
353	two array-refs with path-relative entry names.	660	two array-refs with path-relative entry names.
354		661
355	Example:	662	Example:
…		…
389	as those tend to return 0 or 1 as link counts, which disables the	696	as those tend to return 0 or 1 as link counts, which disables the
390	directory counting heuristic.	697	directory counting heuristic.
391		698
392	=cut	699	=cut
393		700
394	sub aio_scandir($$$) {	701	sub aio_scandir($$;$) {
		702	aio_block {
395	my ($path, $maxreq, $cb) = @_;	703	my ($path, $maxreq, $cb) = @_;
396		704
		705	my $pri = aioreq_pri;
		706
		707	my $grp = aio_group $cb;
		708
397	$maxreq = 8 if $maxreq <= 0;	709	$maxreq = 4 if $maxreq <= 0;
398		710
399	# stat once	711	# stat once
		712	aioreq_pri $pri;
400	aio_stat $path, sub {	713	add $grp aio_stat $path, sub {
401	return $cb->() if $_[0];	714	return $grp->result () if $_[0];
402	my $now = time;	715	my $now = time;
403	my $hash1 = join ":", (stat _)[0,1,3,7,9];	716	my $hash1 = join ":", (stat _)[0,1,3,7,9];
404		717
405	# read the directory entries	718	# read the directory entries
		719	aioreq_pri $pri;
406	aio_readdir $path, sub {	720	add $grp aio_readdir $path, sub {
407	my $entries = shift	721	my $entries = shift
408	or return $cb->();	722	or return $grp->result ();
409		723
410	# stat the dir another time	724	# stat the dir another time
		725	aioreq_pri $pri;
411	aio_stat $path, sub {	726	add $grp aio_stat $path, sub {
412	my $hash2 = join ":", (stat _)[0,1,3,7,9];	727	my $hash2 = join ":", (stat _)[0,1,3,7,9];
413		728
414	my $ndirs;	729	my $ndirs;
415		730
416	# take the slow route if anything looks fishy	731	# take the slow route if anything looks fishy
417	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	732	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
418	$ndirs = -1;	733	$ndirs = -1;
419	} else {	734	} else {
420	# if nlink == 2, we are finished	735	# if nlink == 2, we are finished
421	# on non-posix-fs's, we rely on nlink < 2	736	# on non-posix-fs's, we rely on nlink < 2
422	$ndirs = (stat _)[3] - 2	737	$ndirs = (stat _)[3] - 2
423	or return $cb->([], $entries);	738	or return $grp->result ([], $entries);
424	}
425
426	# sort into likely dirs and likely nondirs
427	# dirs == files without ".", short entries first
428	$entries = [map $_->[0],
429	sort { $b->[1] cmp $a->[1] }
430	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
431	@$entries];
432
433	my (@dirs, @nondirs);
434
435	my ($statcb, $schedcb);
436	my $nreq = 0;
437
438	$schedcb = sub {
439	if (@$entries) {
440	if ($nreq < $maxreq) {
441	my $ent = pop @$entries;
442	$nreq++;
443	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
444	}
445	} elsif (!$nreq) {
446	# finished
447	undef $statcb;
448	undef $schedcb;
449	$cb->(\@dirs, \@nondirs) if $cb;
450	undef $cb;
451	}	739	}
		740
		741	# sort into likely dirs and likely nondirs
		742	# dirs == files without ".", short entries first
		743	$entries = [map $_->[0],
		744	sort { $b->[1] cmp $a->[1] }
		745	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		746	@$entries];
		747
		748	my (@dirs, @nondirs);
		749
		750	my $statgrp = add $grp aio_group sub {
		751	$grp->result (\@dirs, \@nondirs);
		752	};
		753
		754	limit $statgrp $maxreq;
		755	feed $statgrp sub {
		756	return unless @$entries;
		757	my $entry = pop @$entries;
		758
		759	aioreq_pri $pri;
		760	add $statgrp aio_stat "$path/$entry/.", sub {
		761	if ($_[0] < 0) {
		762	push @nondirs, $entry;
		763	} else {
		764	# need to check for real directory
		765	aioreq_pri $pri;
		766	add $statgrp aio_lstat "$path/$entry", sub {
		767	if (-d _) {
		768	push @dirs, $entry;
		769
		770	unless (--$ndirs) {
		771	push @nondirs, @$entries;
		772	feed $statgrp;
		773	}
		774	} else {
		775	push @nondirs, $entry;
		776	}
		777	}
		778	}
		779	};
		780	};
452	};	781	};
453	$statcb = sub {
454	my ($status, $entry) = @_;
455
456	if ($status < 0) {
457	$nreq--;
458	push @nondirs, $entry;
459	&$schedcb;
460	} else {
461	# need to check for real directory
462	aio_lstat "$path/$entry", sub {
463	$nreq--;
464
465	if (-d _) {
466	push @dirs, $entry;
467
468	if (!--$ndirs) {
469	push @nondirs, @$entries;
470	$entries = [];
471	}
472	} else {
473	push @nondirs, $entry;
474	}
475
476	&$schedcb;
477	}
478	}
479	};
480
481	&$schedcb while @$entries && $nreq < $maxreq;
482	};	782	};
483	};	783	};
		784
		785	$grp
484	};	786	}
		787	}
		788
		789	=item aio_rmtree $path, $callback->($status)
		790
		791	Delete a directory tree starting (and including) C<$path>, return the
		792	status of the final C<rmdir> only. This is a composite request that
		793	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		794	everything else.
		795
		796	=cut
		797
		798	sub aio_rmtree;
		799	sub aio_rmtree($;$) {
		800	aio_block {
		801	my ($path, $cb) = @_;
		802
		803	my $pri = aioreq_pri;
		804	my $grp = aio_group $cb;
		805
		806	aioreq_pri $pri;
		807	add $grp aio_scandir $path, 0, sub {
		808	my ($dirs, $nondirs) = @_;
		809
		810	my $dirgrp = aio_group sub {
		811	add $grp aio_rmdir $path, sub {
		812	$grp->result ($_[0]);
		813	};
		814	};
		815
		816	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		817	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		818
		819	add $grp $dirgrp;
		820	};
		821
		822	$grp
		823	}
485	}	824	}
486		825
487	=item aio_fsync $fh, $callback->($status)	826	=item aio_fsync $fh, $callback->($status)
488		827
489	Asynchronously call fsync on the given filehandle and call the callback	828	Asynchronously call fsync on the given filehandle and call the callback
…		…
495	callback with the fdatasync result code.	834	callback with the fdatasync result code.
496		835
497	If this call isn't available because your OS lacks it or it couldn't be	836	If this call isn't available because your OS lacks it or it couldn't be
498	detected, it will be emulated by calling C<fsync> instead.	837	detected, it will be emulated by calling C<fsync> instead.
499		838
500	=item aio_group $callback->()	839	=item aio_group $callback->(...)
501		840
		841	This is a very special aio request: Instead of doing something, it is a
		842	container for other aio requests, which is useful if you want to bundle
		843	many requests into a single, composite, request with a definite callback
		844	and the ability to cancel the whole request with its subrequests.
		845
		846	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		847	for more info.
		848
		849	Example:
		850
		851	my $grp = aio_group sub {
		852	print "all stats done\n";
		853	};
		854
		855	add $grp
		856	(aio_stat ...),
		857	(aio_stat ...),
		858	...;
		859
		860	=item aio_nop $callback->()
		861
		862	This is a special request - it does nothing in itself and is only used for
		863	side effects, such as when you want to add a dummy request to a group so
		864	that finishing the requests in the group depends on executing the given
		865	code.
		866
		867	While this request does nothing, it still goes through the execution
		868	phase and still requires a worker thread. Thus, the callback will not
		869	be executed immediately but only after other requests in the queue have
		870	entered their execution phase. This can be used to measure request
		871	latency.
		872
502	=item aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	873	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
503		874
504	Mainly used for debugging and benchmarking, this aio request puts one of	875	Mainly used for debugging and benchmarking, this aio request puts one of
505	the request workers to sleep for the given time.	876	the request workers to sleep for the given time.
506		877
		878	While it is theoretically handy to have simple I/O scheduling requests
		879	like sleep and file handle readable/writable, the overhead this creates is
		880	immense (it blocks a thread for a long time) so do not use this function
		881	except to put your application under artificial I/O pressure.
		882
507	=back	883	=back
508		884
509	=head2 IO::AIO::REQ CLASS	885	=head2 IO::AIO::REQ CLASS
510		886
511	All non-aggregate C<aio_*> functions return an object of this class when	887	All non-aggregate C<aio_*> functions return an object of this class when
512	called in non-void context.	888	called in non-void context.
513		889
514	A request always moves through the following five states in its lifetime,
515	in order: B<ready> (request has been created, but has not been executed
516	yet), B<execute> (request is currently being executed), B<pending>
517	(request has been executed but callback has not been called yet),
518	B<result> (results are being processed synchronously, includes calling the
519	callback) and B<done> (request has reached the end of its lifetime and
520	holds no resources anymore).
521
522	=over 4	890	=over 4
523		891
524	=item $req->cancel	892	=item cancel $req
525		893
526	Cancels the request, if possible. Has the effect of skipping execution	894	Cancels the request, if possible. Has the effect of skipping execution
527	when entering the B<execute> state and skipping calling the callback when	895	when entering the B<execute> state and skipping calling the callback when
528	entering the the B<result> state, but will leave the request otherwise	896	entering the the B<result> state, but will leave the request otherwise
529	untouched. That means that requests that currently execute will not be	897	untouched. That means that requests that currently execute will not be
530	stopped and resources held by the request will not be freed prematurely.	898	stopped and resources held by the request will not be freed prematurely.
531		899
		900	=item cb $req $callback->(...)
		901
		902	Replace (or simply set) the callback registered to the request.
		903
532	=back	904	=back
533		905
		906	=head2 IO::AIO::GRP CLASS
		907
		908	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		909	objects of this class, too.
		910
		911	A IO::AIO::GRP object is a special request that can contain multiple other
		912	aio requests.
		913
		914	You create one by calling the C<aio_group> constructing function with a
		915	callback that will be called when all contained requests have entered the
		916	C<done> state:
		917
		918	my $grp = aio_group sub {
		919	print "all requests are done\n";
		920	};
		921
		922	You add requests by calling the C<add> method with one or more
		923	C<IO::AIO::REQ> objects:
		924
		925	$grp->add (aio_unlink "...");
		926
		927	add $grp aio_stat "...", sub {
		928	$_[0] or return $grp->result ("error");
		929
		930	# add another request dynamically, if first succeeded
		931	add $grp aio_open "...", sub {
		932	$grp->result ("ok");
		933	};
		934	};
		935
		936	This makes it very easy to create composite requests (see the source of
		937	C<aio_move> for an application) that work and feel like simple requests.
		938
		939	=over 4
		940
		941	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		942	C<IO::AIO::poll_cb>, just like any other request.
		943
		944	=item * They can be canceled like any other request. Canceling will cancel not
		945	only the request itself, but also all requests it contains.
		946
		947	=item * They can also can also be added to other IO::AIO::GRP objects.
		948
		949	=item * You must not add requests to a group from within the group callback (or
		950	any later time).
		951
		952	=back
		953
		954	Their lifetime, simplified, looks like this: when they are empty, they
		955	will finish very quickly. If they contain only requests that are in the
		956	C<done> state, they will also finish. Otherwise they will continue to
		957	exist.
		958
		959	That means after creating a group you have some time to add requests. And
		960	in the callbacks of those requests, you can add further requests to the
		961	group. And only when all those requests have finished will the the group
		962	itself finish.
		963
		964	=over 4
		965
		966	=item add $grp ...
		967
		968	=item $grp->add (...)
		969
		970	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		971	be added, including other groups, as long as you do not create circular
		972	dependencies.
		973
		974	Returns all its arguments.
		975
		976	=item $grp->cancel_subs
		977
		978	Cancel all subrequests and clears any feeder, but not the group request
		979	itself. Useful when you queued a lot of events but got a result early.
		980
		981	=item $grp->result (...)
		982
		983	Set the result value(s) that will be passed to the group callback when all
		984	subrequests have finished and set thre groups errno to the current value
		985	of errno (just like calling C<errno> without an error number). By default,
		986	no argument will be passed and errno is zero.
		987
		988	=item $grp->errno ([$errno])
		989
		990	Sets the group errno value to C<$errno>, or the current value of errno
		991	when the argument is missing.
		992
		993	Every aio request has an associated errno value that is restored when
		994	the callback is invoked. This method lets you change this value from its
		995	default (0).
		996
		997	Calling C<result> will also set errno, so make sure you either set C<$!>
		998	before the call to C<result>, or call c<errno> after it.
		999
		1000	=item feed $grp $callback->($grp)
		1001
		1002	Sets a feeder/generator on this group: every group can have an attached
		1003	generator that generates requests if idle. The idea behind this is that,
		1004	although you could just queue as many requests as you want in a group,
		1005	this might starve other requests for a potentially long time. For
		1006	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		1007	requests, delaying any later requests for a long time.
		1008
		1009	To avoid this, and allow incremental generation of requests, you can
		1010	instead a group and set a feeder on it that generates those requests. The
		1011	feed callback will be called whenever there are few enough (see C<limit>,
		1012	below) requests active in the group itself and is expected to queue more
		1013	requests.
		1014
		1015	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1016	not impose any limits).
		1017
		1018	If the feed does not queue more requests when called, it will be
		1019	automatically removed from the group.
		1020
		1021	If the feed limit is C<0>, it will be set to C<2> automatically.
		1022
		1023	Example:
		1024
		1025	# stat all files in @files, but only ever use four aio requests concurrently:
		1026
		1027	my $grp = aio_group sub { print "finished\n" };
		1028	limit $grp 4;
		1029	feed $grp sub {
		1030	my $file = pop @files
		1031	or return;
		1032
		1033	add $grp aio_stat $file, sub { ... };
		1034	};
		1035
		1036	=item limit $grp $num
		1037
		1038	Sets the feeder limit for the group: The feeder will be called whenever
		1039	the group contains less than this many requests.
		1040
		1041	Setting the limit to C<0> will pause the feeding process.
		1042
		1043	=back
		1044
534	=head2 SUPPORT FUNCTIONS	1045	=head2 SUPPORT FUNCTIONS
		1046
		1047	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
535		1048
536	=over 4	1049	=over 4
537		1050
538	=item $fileno = IO::AIO::poll_fileno	1051	=item $fileno = IO::AIO::poll_fileno
539		1052
…		…
544		1057
545	See C<poll_cb> for an example.	1058	See C<poll_cb> for an example.
546		1059
547	=item IO::AIO::poll_cb	1060	=item IO::AIO::poll_cb
548		1061
549	Process all outstanding events on the result pipe. You have to call this	1062	Process some outstanding events on the result pipe. You have to call this
550	regularly. Returns the number of events processed. Returns immediately	1063	regularly. Returns the number of events processed. Returns immediately
551	when no events are outstanding.	1064	when no events are outstanding. The amount of events processed depends on
		1065	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1066
		1067	If not all requests were processed for whatever reason, the filehandle
		1068	will still be ready when C<poll_cb> returns.
552		1069
553	Example: Install an Event watcher that automatically calls	1070	Example: Install an Event watcher that automatically calls
554	IO::AIO::poll_cb with high priority:	1071	IO::AIO::poll_cb with high priority:
555		1072
556	Event->io (fd => IO::AIO::poll_fileno,	1073	Event->io (fd => IO::AIO::poll_fileno,
557	poll => 'r', async => 1,	1074	poll => 'r', async => 1,
558	cb => \&IO::AIO::poll_cb);	1075	cb => \&IO::AIO::poll_cb);
559		1076
		1077	=item IO::AIO::max_poll_reqs $nreqs
		1078
		1079	=item IO::AIO::max_poll_time $seconds
		1080
		1081	These set the maximum number of requests (default C<0>, meaning infinity)
		1082	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1083	the maximum amount of time (default C<0>, meaning infinity) spent in
		1084	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1085	of time C<poll_cb> is allowed to use).
		1086
		1087	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1088	syscall per request processed, which is not normally a problem unless your
		1089	callbacks are really really fast or your OS is really really slow (I am
		1090	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1091
		1092	Setting these is useful if you want to ensure some level of
		1093	interactiveness when perl is not fast enough to process all requests in
		1094	time.
		1095
		1096	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1097
		1098	Example: Install an Event watcher that automatically calls
		1099	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1100	program get the CPU sometimes even under high AIO load.
		1101
		1102	# try not to spend much more than 0.1s in poll_cb
		1103	IO::AIO::max_poll_time 0.1;
		1104
		1105	# use a low priority so other tasks have priority
		1106	Event->io (fd => IO::AIO::poll_fileno,
		1107	poll => 'r', nice => 1,
		1108	cb => &IO::AIO::poll_cb);
		1109
560	=item IO::AIO::poll_wait	1110	=item IO::AIO::poll_wait
561		1111
		1112	If there are any outstanding requests and none of them in the result
562	Wait till the result filehandle becomes ready for reading (simply does a	1113	phase, wait till the result filehandle becomes ready for reading (simply
563	C<select> on the filehandle. This is useful if you want to synchronously wait	1114	does a C<select> on the filehandle. This is useful if you want to
564	for some requests to finish).	1115	synchronously wait for some requests to finish).
565		1116
566	See C<nreqs> for an example.	1117	See C<nreqs> for an example.
567		1118
		1119	=item IO::AIO::poll
		1120
		1121	Waits until some requests have been handled.
		1122
		1123	Returns the number of requests processed, but is otherwise strictly
		1124	equivalent to:
		1125
		1126	IO::AIO::poll_wait, IO::AIO::poll_cb
		1127
568	=item IO::AIO::nreqs	1128	=item IO::AIO::flush
569		1129
570	Returns the number of requests currently outstanding (i.e. for which their	1130	Wait till all outstanding AIO requests have been handled.
571	callback has not been invoked yet).
572		1131
573	Example: wait till there are no outstanding requests anymore:	1132	Strictly equivalent to:
574		1133
575	IO::AIO::poll_wait, IO::AIO::poll_cb	1134	IO::AIO::poll_wait, IO::AIO::poll_cb
576	while IO::AIO::nreqs;	1135	while IO::AIO::nreqs;
577		1136
578	=item IO::AIO::flush	1137	=back
579		1138
580	Wait till all outstanding AIO requests have been handled.	1139	=head3 CONTROLLING THE NUMBER OF THREADS
581		1140
582	Strictly equivalent to:	1141	=over
583
584	IO::AIO::poll_wait, IO::AIO::poll_cb
585	while IO::AIO::nreqs;
586
587	=item IO::AIO::poll
588
589	Waits until some requests have been handled.
590
591	Strictly equivalent to:
592
593	IO::AIO::poll_wait, IO::AIO::poll_cb
594	if IO::AIO::nreqs;
595		1142
596	=item IO::AIO::min_parallel $nthreads	1143	=item IO::AIO::min_parallel $nthreads
597		1144
598	Set the minimum number of AIO threads to C<$nthreads>. The current default	1145	Set the minimum number of AIO threads to C<$nthreads>. The current
599	is C<4>, which means four asynchronous operations can be done at one time	1146	default is C<8>, which means eight asynchronous operations can execute
600	(the number of outstanding operations, however, is unlimited).	1147	concurrently at any one time (the number of outstanding requests,
		1148	however, is unlimited).
601		1149
602	IO::AIO starts threads only on demand, when an AIO request is queued and	1150	IO::AIO starts threads only on demand, when an AIO request is queued and
603	no free thread exists.	1151	no free thread exists. Please note that queueing up a hundred requests can
		1152	create demand for a hundred threads, even if it turns out that everything
		1153	is in the cache and could have been processed faster by a single thread.
604		1154
605	It is recommended to keep the number of threads low, as some Linux	1155	It is recommended to keep the number of threads relatively low, as some
606	kernel versions will scale negatively with the number of threads (higher	1156	Linux kernel versions will scale negatively with the number of threads
607	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1157	(higher parallelity => MUCH higher latency). With current Linux 2.6
608	threads should be fine.	1158	versions, 4-32 threads should be fine.
609		1159
610	Under most circumstances you don't need to call this function, as the	1160	Under most circumstances you don't need to call this function, as the
611	module selects a default that is suitable for low to moderate load.	1161	module selects a default that is suitable for low to moderate load.
612		1162
613	=item IO::AIO::max_parallel $nthreads	1163	=item IO::AIO::max_parallel $nthreads
…		…
622	This module automatically runs C<max_parallel 0> at program end, to ensure	1172	This module automatically runs C<max_parallel 0> at program end, to ensure
623	that all threads are killed and that there are no outstanding requests.	1173	that all threads are killed and that there are no outstanding requests.
624		1174
625	Under normal circumstances you don't need to call this function.	1175	Under normal circumstances you don't need to call this function.
626		1176
		1177	=item IO::AIO::max_idle $nthreads
		1178
		1179	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1180	threads that did not get a request to process within 10 seconds). That
		1181	means if a thread becomes idle while C<$nthreads> other threads are also
		1182	idle, it will free its resources and exit.
		1183
		1184	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1185	to allow for extremely high load situations, but want to free resources
		1186	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1187
		1188	The default is probably ok in most situations, especially if thread
		1189	creation is fast. If thread creation is very slow on your system you might
		1190	want to use larger values.
		1191
627	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1192	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1193
		1194	This is a very bad function to use in interactive programs because it
		1195	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1196	use an C<aio_group> together with a feed callback.
628		1197
629	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1198	Sets the maximum number of outstanding requests to C<$nreqs>. If you
630	try to queue up more than this number of requests, the caller will block until	1199	to queue up more than this number of requests, the next call to the
631	some requests have been handled.	1200	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1201	function will block until the limit is no longer exceeded.
632		1202
633	The default is very large, so normally there is no practical limit. If you	1203	The default value is very large, so there is no practical limit on the
634	queue up many requests in a loop it often improves speed if you set	1204	number of outstanding requests.
635	this to a relatively low number, such as C<100>.
636		1205
637	Under normal circumstances you don't need to call this function.	1206	You can still queue as many requests as you want. Therefore,
		1207	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1208	as a stop gap to shield against fatal memory overflow (with large values).
		1209
		1210	=back
		1211
		1212	=head3 STATISTICAL INFORMATION
		1213
		1214	=over
		1215
		1216	=item IO::AIO::nreqs
		1217
		1218	Returns the number of requests currently in the ready, execute or pending
		1219	states (i.e. for which their callback has not been invoked yet).
		1220
		1221	Example: wait till there are no outstanding requests anymore:
		1222
		1223	IO::AIO::poll_wait, IO::AIO::poll_cb
		1224	while IO::AIO::nreqs;
		1225
		1226	=item IO::AIO::nready
		1227
		1228	Returns the number of requests currently in the ready state (not yet
		1229	executed).
		1230
		1231	=item IO::AIO::npending
		1232
		1233	Returns the number of requests currently in the pending state (executed,
		1234	but not yet processed by poll_cb).
638		1235
639	=back	1236	=back
640		1237
641	=cut	1238	=cut
642		1239
…		…
654	or return undef;	1251	or return undef;
655		1252
656	*$sym	1253	*$sym
657	}	1254	}
658		1255
659	min_parallel 4;	1256	min_parallel 8;
660		1257
661	END {	1258	END { flush }
662	max_parallel 0;
663	}
664		1259
665	1;	1260	1;
666		1261
667	=head2 FORK BEHAVIOUR	1262	=head2 FORK BEHAVIOUR
668		1263
669	This module should do "the right thing" when the process using it forks:	1264	This module should do "the right thing" when the process using it forks:
670		1265
671	Before the fork, IO::AIO enters a quiescent state where no requests	1266	Before the fork, IO::AIO enters a quiescent state where no requests
672	can be added in other threads and no results will be processed. After	1267	can be added in other threads and no results will be processed. After
673	the fork the parent simply leaves the quiescent state and continues	1268	the fork the parent simply leaves the quiescent state and continues
674	request/result processing, while the child clears the request/result	1269	request/result processing, while the child frees the request/result queue
675	queue (so the requests started before the fork will only be handled in	1270	(so that the requests started before the fork will only be handled in the
676	the parent). Threads will be started on demand until the limit ste in the	1271	parent). Threads will be started on demand until the limit set in the
677	parent process has been reached again.	1272	parent process has been reached again.
678		1273
679	In short: the parent will, after a short pause, continue as if fork had	1274	In short: the parent will, after a short pause, continue as if fork had
680	not been called, while the child will act as if IO::AIO has not been used	1275	not been called, while the child will act as if IO::AIO has not been used
681	yet.	1276	yet.
682		1277
		1278	=head2 MEMORY USAGE
		1279
		1280	Per-request usage:
		1281
		1282	Each aio request uses - depending on your architecture - around 100-200
		1283	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1284	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1285	scalars and other data passed into aio requests will also be locked and
		1286	will consume memory till the request has entered the done state.
		1287
		1288	This is now awfully much, so queuing lots of requests is not usually a
		1289	problem.
		1290
		1291	Per-thread usage:
		1292
		1293	In the execution phase, some aio requests require more memory for
		1294	temporary buffers, and each thread requires a stack and other data
		1295	structures (usually around 16k-128k, depending on the OS).
		1296
		1297	=head1 KNOWN BUGS
		1298
		1299	Known bugs will be fixed in the next release.
		1300
683	=head1 SEE ALSO	1301	=head1 SEE ALSO
684		1302
685	L<Coro>, L<Linux::AIO> (obsolete).	1303	L<Coro::AIO>.
686		1304
687	=head1 AUTHOR	1305	=head1 AUTHOR
688		1306
689	Marc Lehmann <schmorp@schmorp.de>	1307	Marc Lehmann <schmorp@schmorp.de>
690	http://home.schmorp.de/	1308	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs. Revision 1.107 by root, Fri Jun 1 05:52:59 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs.
Revision 1.107 by root, Fri Jun 1 05:52:59 2007 UTC