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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.61 by root, Sun Oct 22 13:52:11 2006 UTC vs.
Revision 1.105 by root, Sun Mar 25 00:20:27 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
…		…
18	};	19	};
19		20
20	# version 2+ has request and group objects	21	# version 2+ has request and group objects
21	use IO::AIO 2;	22	use IO::AIO 2;
22		23
		24	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
25		27
26	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
…		…
50	=head1 DESCRIPTION	52	=head1 DESCRIPTION
51		53
52	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
53	operating system supports.	55	operating system supports.
54		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
55	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
56	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
57	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
58	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
59	aio functions available on many operating systems. However, they are often	78	functions available on many operating systems. However, they are often
60	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
61	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
62	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.
63		83
64	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-)
65	currently not reentrant, so use appropriate locking yourself, always call	85	threads, it is currently not reentrant in any way, so use appropriate
66	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
67	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
68		184
69	=cut	185	=cut
70		186
71	package IO::AIO;	187	package IO::AIO;
72		188
…		…
74	use strict 'vars';	190	use strict 'vars';
75		191
76	use base 'Exporter';	192	use base 'Exporter';
77		193
78	BEGIN {	194	BEGIN {
79	our $VERSION = '2.0';	195	our $VERSION = '2.33';
80		196
81	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
82	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
83	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
84	aio_group);	200	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir);
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
		202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
86		206
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		208
89	require XSLoader;	209	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
91	}	211	}
92		212
93	=head1 FUNCTIONS	213	=head1 FUNCTIONS
94		214
95	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
96		216
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
100	which must be a code reference. This code reference will get called with	220	which must be a code reference. This code reference will get called with
…		…
103	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
104		224
105	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	226	internally until the request has finished.
107		227
108	All requests return objects of type L<IO::AIO::REQ> that allow further	228	All functions return request objects of type L<IO::AIO::REQ> that allow
109	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
110		230
111	The pathnames you pass to these routines I<must> be absolute and	231	The pathnames you pass to these routines I<must> be absolute and
112	encoded in byte form. The reason for the former is that at the time the	232	encoded as octets. The reason for the former is that at the time the
113	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
115	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
116		237
117	To encode pathnames to byte form, either make sure you either: a)	238	To encode pathnames as octets, either make sure you either: a) always pass
118	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
119	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
120	your pathnames to the locale (or other) encoding in effect in the user	241	your pathnames to the locale (or other) encoding in effect in the user
121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	use something else.	243	use something else to ensure your scalar has the correct contents.
		244
		245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		246	handles correctly wether it is set or not.
123		247
124	=over 4	248	=over 4
		249
		250	=item $prev_pri = aioreq_pri [$pri]
		251
		252	Returns the priority value that would be used for the next request and, if
		253	C<$pri> is given, sets the priority for the next aio request.
		254
		255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
		258
		259	The priority will be reset to C<0> after each call to one of the C<aio_*>
		260	functions.
		261
		262	Example: open a file with low priority, then read something from it with
		263	higher priority so the read request is serviced before other low priority
		264	open requests (potentially spamming the cache):
		265
		266	aioreq_pri -3;
		267	aio_open ..., sub {
		268	return unless $_[0];
		269
		270	aioreq_pri -2;
		271	aio_read $_[0], ..., sub {
		272	...
		273	};
		274	};
		275
		276	=item aioreq_nice $pri_adjust
		277
		278	Similar to C<aioreq_pri>, but subtracts the given value from the current
		279	priority, so the effect is cumulative.
125		280
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	281	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		282
128	Asynchronously open or create a file and call the callback with a newly	283	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	284	created filehandle for the file.
…		…
135	list. They are the same as used by C<sysopen>.	290	list. They are the same as used by C<sysopen>.
136		291
137	Likewise, C<$mode> specifies the mode of the newly created file, if it	292	Likewise, C<$mode> specifies the mode of the newly created file, if it
138	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	293	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
139	except that it is mandatory (i.e. use C<0> if you don't create new files,	294	except that it is mandatory (i.e. use C<0> if you don't create new files,
140	and C<0666> or C<0777> if you do).	295	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		296	by the umask in effect then the request is being executed, so better never
		297	change the umask.
141		298
142	Example:	299	Example:
143		300
144	aio_open "/etc/passwd", O_RDONLY, 0, sub {	301	aio_open "/etc/passwd", O_RDONLY, 0, sub {
145	if ($_[0]) {	302	if ($_[0]) {
…		…
180	aio_read $fh, 7, 15, $buffer, 0, sub {	337	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	338	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	339	print "read $_[0] bytes: <$buffer>\n";
183	};	340	};
184		341
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	[EXPERIMENTAL due to internal aio_group use]
188
189	Try to move the I<file> (directories not supported as either source or
190	destination) from C<$srcpath> to C<$dstpath> and call the callback with
191	the C<0> (error) or C<-1> ok.
192
193	This is a composite request that tries to rename(2) the file first. If
194	rename files with C<EXDEV>, it creates the destination file with mode 0200
195	and copies the contents of the source file into it using C<aio_sendfile>,
196	followed by restoring atime, mtime, access mode and uid/gid, in that
197	order, and unlinking the C<$srcpath>.
198
199	If an error occurs, the partial destination file will be unlinked, if
200	possible, except when setting atime, mtime, access mode and uid/gid, where
201	errors are being ignored.
202
203	=cut
204
205	sub aio_move($$$) {
206	my ($src, $dst, $cb) = @_;
207
208	my $grp = aio_group $cb;
209
210	add $grp aio_rename $src, $dst, sub {
211	if ($_[0] && $! == EXDEV) {
212	add $grp aio_open $src, O_RDONLY, 0, sub {
213	if (my $src_fh = $_[0]) {
214	my @stat = stat $src_fh;
215
216	add $grp aio_open $dst, O_WRONLY, 0200, sub {
217	if (my $dst_fh = $_[0]) {
218	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
219	close $src_fh;
220
221	if ($_[0] == $stat[7]) {
222	utime $stat[8], $stat[9], $dst;
223	chmod $stat[2] & 07777, $dst_fh;
224	chown $stat[4], $stat[5], $dst_fh;
225	close $dst_fh;
226
227	add $grp aio_unlink $src, sub {
228	$grp->result ($_[0]);
229	};
230	} else {
231	my $errno = $!;
232	add $grp aio_unlink $dst, sub {
233	$! = $errno;
234	$grp->result (-1);
235	};
236	}
237	};
238	} else {
239	$grp->result (-1);
240	}
241	},
242
243	} else {
244	$grp->result (-1);
245	}
246	};
247	} else {
248	$grp->result ($_[0]);
249	}
250	};
251
252	$grp
253	}
254
255	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	342	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
256		343
257	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	344	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
258	reading at byte offset C<$in_offset>, and starts writing at the current	345	reading at byte offset C<$in_offset>, and starts writing at the current
259	file offset of C<$out_fh>. Because of that, it is not safe to issue more	346	file offset of C<$out_fh>. Because of that, it is not safe to issue more
…		…
314	=item aio_unlink $pathname, $callback->($status)	401	=item aio_unlink $pathname, $callback->($status)
315		402
316	Asynchronously unlink (delete) a file and call the callback with the	403	Asynchronously unlink (delete) a file and call the callback with the
317	result code.	404	result code.
318		405
		406	=item aio_mknod $path, $mode, $dev, $callback->($status)
		407
		408	[EXPERIMENTAL]
		409
		410	Asynchronously create a device node (or fifo). See mknod(2).
		411
		412	The only (POSIX-) portable way of calling this function is:
		413
		414	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		415
319	=item aio_link $srcpath, $dstpath, $callback->($status)	416	=item aio_link $srcpath, $dstpath, $callback->($status)
320		417
321	Asynchronously create a new link to the existing object at C<$srcpath> at	418	Asynchronously create a new link to the existing object at C<$srcpath> at
322	the path C<$dstpath> and call the callback with the result code.	419	the path C<$dstpath> and call the callback with the result code.
323		420
324	=item aio_symlink $srcpath, $dstpath, $callback->($status)	421	=item aio_symlink $srcpath, $dstpath, $callback->($status)
325		422
326	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	423	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
327	the path C<$dstpath> and call the callback with the result code.	424	the path C<$dstpath> and call the callback with the result code.
328		425
		426	=item aio_readlink $path, $callback->($link)
		427
		428	Asynchronously read the symlink specified by C<$path> and pass it to
		429	the callback. If an error occurs, nothing or undef gets passed to the
		430	callback.
		431
329	=item aio_rename $srcpath, $dstpath, $callback->($status)	432	=item aio_rename $srcpath, $dstpath, $callback->($status)
330		433
331	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	434	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
332	rename(2) and call the callback with the result code.	435	rename(2) and call the callback with the result code.
		436
		437	=item aio_mkdir $pathname, $mode, $callback->($status)
		438
		439	Asynchronously mkdir (create) a directory and call the callback with
		440	the result code. C<$mode> will be modified by the umask at the time the
		441	request is executed, so do not change your umask.
333		442
334	=item aio_rmdir $pathname, $callback->($status)	443	=item aio_rmdir $pathname, $callback->($status)
335		444
336	Asynchronously rmdir (delete) a directory and call the callback with the	445	Asynchronously rmdir (delete) a directory and call the callback with the
337	result code.	446	result code.
…		…
343	sorted, and will B<NOT> include the C<.> and C<..> entries.	452	sorted, and will B<NOT> include the C<.> and C<..> entries.
344		453
345	The callback a single argument which is either C<undef> or an array-ref	454	The callback a single argument which is either C<undef> or an array-ref
346	with the filenames.	455	with the filenames.
347		456
		457	=item aio_load $path, $data, $callback->($status)
		458
		459	This is a composite request that tries to fully load the given file into
		460	memory. Status is the same as with aio_read.
		461
		462	=cut
		463
		464	sub aio_load($$;$) {
		465	aio_block {
		466	my ($path, undef, $cb) = @_;
		467	my $data = \$_[1];
		468
		469	my $pri = aioreq_pri;
		470	my $grp = aio_group $cb;
		471
		472	aioreq_pri $pri;
		473	add $grp aio_open $path, O_RDONLY, 0, sub {
		474	my $fh = shift
		475	or return $grp->result (-1);
		476
		477	aioreq_pri $pri;
		478	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		479	$grp->result ($_[0]);
		480	};
		481	};
		482
		483	$grp
		484	}
		485	}
		486
		487	=item aio_copy $srcpath, $dstpath, $callback->($status)
		488
		489	Try to copy the I<file> (directories not supported as either source or
		490	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		491	the C<0> (error) or C<-1> ok.
		492
		493	This is a composite request that it creates the destination file with
		494	mode 0200 and copies the contents of the source file into it using
		495	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		496	uid/gid, in that order.
		497
		498	If an error occurs, the partial destination file will be unlinked, if
		499	possible, except when setting atime, mtime, access mode and uid/gid, where
		500	errors are being ignored.
		501
		502	=cut
		503
		504	sub aio_copy($$;$) {
		505	aio_block {
		506	my ($src, $dst, $cb) = @_;
		507
		508	my $pri = aioreq_pri;
		509	my $grp = aio_group $cb;
		510
		511	aioreq_pri $pri;
		512	add $grp aio_open $src, O_RDONLY, 0, sub {
		513	if (my $src_fh = $_[0]) {
		514	my @stat = stat $src_fh;
		515
		516	aioreq_pri $pri;
		517	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		518	if (my $dst_fh = $_[0]) {
		519	aioreq_pri $pri;
		520	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		521	if ($_[0] == $stat[7]) {
		522	$grp->result (0);
		523	close $src_fh;
		524
		525	# those should not normally block. should. should.
		526	utime $stat[8], $stat[9], $dst;
		527	chmod $stat[2] & 07777, $dst_fh;
		528	chown $stat[4], $stat[5], $dst_fh;
		529	close $dst_fh;
		530	} else {
		531	$grp->result (-1);
		532	close $src_fh;
		533	close $dst_fh;
		534
		535	aioreq $pri;
		536	add $grp aio_unlink $dst;
		537	}
		538	};
		539	} else {
		540	$grp->result (-1);
		541	}
		542	},
		543
		544	} else {
		545	$grp->result (-1);
		546	}
		547	};
		548
		549	$grp
		550	}
		551	}
		552
		553	=item aio_move $srcpath, $dstpath, $callback->($status)
		554
		555	Try to move the I<file> (directories not supported as either source or
		556	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		557	the C<0> (error) or C<-1> ok.
		558
		559	This is a composite request that tries to rename(2) the file first. If
		560	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		561	that is successful, unlinking the C<$srcpath>.
		562
		563	=cut
		564
		565	sub aio_move($$;$) {
		566	aio_block {
		567	my ($src, $dst, $cb) = @_;
		568
		569	my $pri = aioreq_pri;
		570	my $grp = aio_group $cb;
		571
		572	aioreq_pri $pri;
		573	add $grp aio_rename $src, $dst, sub {
		574	if ($_[0] && $! == EXDEV) {
		575	aioreq_pri $pri;
		576	add $grp aio_copy $src, $dst, sub {
		577	$grp->result ($_[0]);
		578
		579	if (!$_[0]) {
		580	aioreq_pri $pri;
		581	add $grp aio_unlink $src;
		582	}
		583	};
		584	} else {
		585	$grp->result ($_[0]);
		586	}
		587	};
		588
		589	$grp
		590	}
		591	}
		592
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	593	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		594
350	[EXPERIMENTAL due to internal aio_group use]
351
352	Scans a directory (similar to C<aio_readdir>) but additionally tries to	595	Scans a directory (similar to C<aio_readdir>) but additionally tries to
353	separate the entries of directory C<$path> into two sets of names, ones	596	efficiently separate the entries of directory C<$path> into two sets of
354	you can recurse into (directories or links to them), and ones you cannot	597	names, directories you can recurse into (directories), and ones you cannot
355	recurse into (everything else).	598	recurse into (everything else, including symlinks to directories).
356		599
357	C<aio_scandir> is a composite request that creates of many sub requests_	600	C<aio_scandir> is a composite request that creates of many sub requests_
358	C<$maxreq> specifies the maximum number of outstanding aio requests that	601	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	this function generates. If it is C<< <= 0 >>, then a suitable default	602	this function generates. If it is C<< <= 0 >>, then a suitable default
360	will be chosen (currently 6).	603	will be chosen (currently 4).
361		604
362	On error, the callback is called without arguments, otherwise it receives	605	On error, the callback is called without arguments, otherwise it receives
363	two array-refs with path-relative entry names.	606	two array-refs with path-relative entry names.
364		607
365	Example:	608	Example:
…		…
399	as those tend to return 0 or 1 as link counts, which disables the	642	as those tend to return 0 or 1 as link counts, which disables the
400	directory counting heuristic.	643	directory counting heuristic.
401		644
402	=cut	645	=cut
403		646
404	sub aio_scandir($$$) {	647	sub aio_scandir($$;$) {
		648	aio_block {
405	my ($path, $maxreq, $cb) = @_;	649	my ($path, $maxreq, $cb) = @_;
406		650
		651	my $pri = aioreq_pri;
		652
407	my $grp = aio_group $cb;	653	my $grp = aio_group $cb;
408		654
409	$maxreq = 6 if $maxreq <= 0;	655	$maxreq = 4 if $maxreq <= 0;
410		656
411	# stat once	657	# stat once
		658	aioreq_pri $pri;
412	add $grp aio_stat $path, sub {	659	add $grp aio_stat $path, sub {
413	return $grp->result () if $_[0];	660	return $grp->result () if $_[0];
414	my $now = time;	661	my $now = time;
415	my $hash1 = join ":", (stat _)[0,1,3,7,9];	662	my $hash1 = join ":", (stat _)[0,1,3,7,9];
416		663
417	# read the directory entries	664	# read the directory entries
		665	aioreq_pri $pri;
418	add $grp aio_readdir $path, sub {	666	add $grp aio_readdir $path, sub {
419	my $entries = shift	667	my $entries = shift
420	or return $grp->result ();	668	or return $grp->result ();
421		669
422	# stat the dir another time	670	# stat the dir another time
		671	aioreq_pri $pri;
423	add $grp aio_stat $path, sub {	672	add $grp aio_stat $path, sub {
424	my $hash2 = join ":", (stat _)[0,1,3,7,9];	673	my $hash2 = join ":", (stat _)[0,1,3,7,9];
425		674
426	my $ndirs;	675	my $ndirs;
427		676
428	# take the slow route if anything looks fishy	677	# take the slow route if anything looks fishy
429	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	678	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
430	$ndirs = -1;	679	$ndirs = -1;
431	} else {	680	} else {
432	# if nlink == 2, we are finished	681	# if nlink == 2, we are finished
433	# on non-posix-fs's, we rely on nlink < 2	682	# on non-posix-fs's, we rely on nlink < 2
434	$ndirs = (stat _)[3] - 2	683	$ndirs = (stat _)[3] - 2
435	or return $grp->result ([], $entries);	684	or return $grp->result ([], $entries);
436	}	685	}
437		686
438	# sort into likely dirs and likely nondirs	687	# sort into likely dirs and likely nondirs
439	# dirs == files without ".", short entries first	688	# dirs == files without ".", short entries first
440	$entries = [map $_->[0],	689	$entries = [map $_->[0],
441	sort { $b->[1] cmp $a->[1] }	690	sort { $b->[1] cmp $a->[1] }
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	691	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];	692	@$entries];
444		693
445	my (@dirs, @nondirs);	694	my (@dirs, @nondirs);
446		695
447	my ($statcb, $schedcb);
448	my $nreq = 0;
449
450	my $statgrp = add $grp aio_group;	696	my $statgrp = add $grp aio_group sub {
451
452	$schedcb = sub {
453	if (@$entries) {
454	if ($nreq < $maxreq) {
455	my $ent = pop @$entries;
456	$nreq++;
457	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
458	}
459	} elsif (!$nreq) {
460	# finished
461	$statgrp->cancel;
462	undef $statcb;
463	undef $schedcb;
464	$grp->result (\@dirs, \@nondirs);	697	$grp->result (\@dirs, \@nondirs);
465	}	698	};
		699
		700	limit $statgrp $maxreq;
		701	feed $statgrp sub {
		702	return unless @$entries;
		703	my $entry = pop @$entries;
		704
		705	aioreq_pri $pri;
		706	add $statgrp aio_stat "$path/$entry/.", sub {
		707	if ($_[0] < 0) {
		708	push @nondirs, $entry;
		709	} else {
		710	# need to check for real directory
		711	aioreq_pri $pri;
		712	add $statgrp aio_lstat "$path/$entry", sub {
		713	if (-d _) {
		714	push @dirs, $entry;
		715
		716	unless (--$ndirs) {
		717	push @nondirs, @$entries;
		718	feed $statgrp;
		719	}
		720	} else {
		721	push @nondirs, $entry;
		722	}
		723	}
		724	}
		725	};
		726	};
466	};	727	};
467	$statcb = sub {
468	my ($status, $entry) = @_;
469
470	if ($status < 0) {
471	$nreq--;
472	push @nondirs, $entry;
473	&$schedcb;
474	} else {
475	# need to check for real directory
476	add $grp aio_lstat "$path/$entry", sub {
477	$nreq--;
478
479	if (-d _) {
480	push @dirs, $entry;
481
482	if (!--$ndirs) {
483	push @nondirs, @$entries;
484	$entries = [];
485	}
486	} else {
487	push @nondirs, $entry;
488	}
489
490	&$schedcb;
491	}
492	}
493	};
494
495	&$schedcb while @$entries && $nreq < $maxreq;
496	};	728	};
497	};	729	};
		730
		731	$grp
498	};	732	}
		733	}
499		734
		735	=item aio_rmtree $path, $callback->($status)
		736
		737	Delete a directory tree starting (and including) C<$path>, return the
		738	status of the final C<rmdir> only. This is a composite request that
		739	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		740	everything else.
		741
		742	=cut
		743
		744	sub aio_rmtree;
		745	sub aio_rmtree($;$) {
		746	aio_block {
		747	my ($path, $cb) = @_;
		748
		749	my $pri = aioreq_pri;
		750	my $grp = aio_group $cb;
		751
		752	aioreq_pri $pri;
		753	add $grp aio_scandir $path, 0, sub {
		754	my ($dirs, $nondirs) = @_;
		755
		756	my $dirgrp = aio_group sub {
		757	add $grp aio_rmdir $path, sub {
		758	$grp->result ($_[0]);
		759	};
		760	};
		761
		762	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		763	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		764
		765	add $grp $dirgrp;
		766	};
		767
500	$grp	768	$grp
		769	}
501	}	770	}
502		771
503	=item aio_fsync $fh, $callback->($status)	772	=item aio_fsync $fh, $callback->($status)
504		773
505	Asynchronously call fsync on the given filehandle and call the callback	774	Asynchronously call fsync on the given filehandle and call the callback
…		…
513	If this call isn't available because your OS lacks it or it couldn't be	782	If this call isn't available because your OS lacks it or it couldn't be
514	detected, it will be emulated by calling C<fsync> instead.	783	detected, it will be emulated by calling C<fsync> instead.
515		784
516	=item aio_group $callback->(...)	785	=item aio_group $callback->(...)
517		786
518	[EXPERIMENTAL]
519
520	This is a very special aio request: Instead of doing something, it is a	787	This is a very special aio request: Instead of doing something, it is a
521	container for other aio requests, which is useful if you want to bundle	788	container for other aio requests, which is useful if you want to bundle
522	many requests into a single, composite, request.	789	many requests into a single, composite, request with a definite callback
		790	and the ability to cancel the whole request with its subrequests.
523		791
524	Returns an object of class L<IO::AIO::GRP>. See its documentation below	792	Returns an object of class L<IO::AIO::GRP>. See its documentation below
525	for more info.	793	for more info.
526		794
527	Example:	795	Example:
…		…
533	add $grp	801	add $grp
534	(aio_stat ...),	802	(aio_stat ...),
535	(aio_stat ...),	803	(aio_stat ...),
536	...;	804	...;
537		805
		806	=item aio_nop $callback->()
		807
		808	This is a special request - it does nothing in itself and is only used for
		809	side effects, such as when you want to add a dummy request to a group so
		810	that finishing the requests in the group depends on executing the given
		811	code.
		812
		813	While this request does nothing, it still goes through the execution
		814	phase and still requires a worker thread. Thus, the callback will not
		815	be executed immediately but only after other requests in the queue have
		816	entered their execution phase. This can be used to measure request
		817	latency.
		818
538	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	819	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
539		820
540	Mainly used for debugging and benchmarking, this aio request puts one of	821	Mainly used for debugging and benchmarking, this aio request puts one of
541	the request workers to sleep for the given time.	822	the request workers to sleep for the given time.
542		823
543	While it is theoretically handy to have simple I/O scheduling requests	824	While it is theoretically handy to have simple I/O scheduling requests
544	like sleep and file handle readable/writable, the overhead this creates	825	like sleep and file handle readable/writable, the overhead this creates is
545	is immense, so do not use this function except to put your application	826	immense (it blocks a thread for a long time) so do not use this function
546	under artificial I/O pressure.	827	except to put your application under artificial I/O pressure.
547		828
548	=back	829	=back
549		830
550	=head2 IO::AIO::REQ CLASS	831	=head2 IO::AIO::REQ CLASS
551		832
552	All non-aggregate C<aio_*> functions return an object of this class when	833	All non-aggregate C<aio_*> functions return an object of this class when
553	called in non-void context.	834	called in non-void context.
554		835
555	A request always moves through the following five states in its lifetime,
556	in order: B<ready> (request has been created, but has not been executed
557	yet), B<execute> (request is currently being executed), B<pending>
558	(request has been executed but callback has not been called yet),
559	B<result> (results are being processed synchronously, includes calling the
560	callback) and B<done> (request has reached the end of its lifetime and
561	holds no resources anymore).
562
563	=over 4	836	=over 4
564		837
565	=item $req->cancel	838	=item cancel $req
566		839
567	Cancels the request, if possible. Has the effect of skipping execution	840	Cancels the request, if possible. Has the effect of skipping execution
568	when entering the B<execute> state and skipping calling the callback when	841	when entering the B<execute> state and skipping calling the callback when
569	entering the the B<result> state, but will leave the request otherwise	842	entering the the B<result> state, but will leave the request otherwise
570	untouched. That means that requests that currently execute will not be	843	untouched. That means that requests that currently execute will not be
571	stopped and resources held by the request will not be freed prematurely.	844	stopped and resources held by the request will not be freed prematurely.
572		845
		846	=item cb $req $callback->(...)
		847
		848	Replace (or simply set) the callback registered to the request.
		849
573	=back	850	=back
574		851
575	=head2 IO::AIO::GRP CLASS	852	=head2 IO::AIO::GRP CLASS
576		853
577	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	854	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
603	};	880	};
604		881
605	This makes it very easy to create composite requests (see the source of	882	This makes it very easy to create composite requests (see the source of
606	C<aio_move> for an application) that work and feel like simple requests.	883	C<aio_move> for an application) that work and feel like simple requests.
607		884
		885	=over 4
		886
608	The IO::AIO::GRP objects will be cleaned up during calls to	887	=item * The IO::AIO::GRP objects will be cleaned up during calls to
609	C<IO::AIO::poll_cb>, just like any other request.	888	C<IO::AIO::poll_cb>, just like any other request.
610		889
611	They can be canceled like any other request. Canceling will cancel not	890	=item * They can be canceled like any other request. Canceling will cancel not
612	only the request itself, but also all requests it contains.	891	only the request itself, but also all requests it contains.
613		892
614	They can also can also be added to other IO::AIO::GRP objects.	893	=item * They can also can also be added to other IO::AIO::GRP objects.
615		894
616	You must not add requests to a group from within the group callback (or	895	=item * You must not add requests to a group from within the group callback (or
617	any later time).	896	any later time).
		897
		898	=back
618		899
619	Their lifetime, simplified, looks like this: when they are empty, they	900	Their lifetime, simplified, looks like this: when they are empty, they
620	will finish very quickly. If they contain only requests that are in the	901	will finish very quickly. If they contain only requests that are in the
621	C<done> state, they will also finish. Otherwise they will continue to	902	C<done> state, they will also finish. Otherwise they will continue to
622	exist.	903	exist.
…		…
626	group. And only when all those requests have finished will the the group	907	group. And only when all those requests have finished will the the group
627	itself finish.	908	itself finish.
628		909
629	=over 4	910	=over 4
630		911
		912	=item add $grp ...
		913
631	=item $grp->add (...)	914	=item $grp->add (...)
632
633	=item add $grp ...
634		915
635	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	916	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
636	be added, including other groups, as long as you do not create circular	917	be added, including other groups, as long as you do not create circular
637	dependencies.	918	dependencies.
638		919
639	Returns all its arguments.	920	Returns all its arguments.
640		921
		922	=item $grp->cancel_subs
		923
		924	Cancel all subrequests and clears any feeder, but not the group request
		925	itself. Useful when you queued a lot of events but got a result early.
		926
641	=item $grp->result (...)	927	=item $grp->result (...)
642		928
643	Set the result value(s) that will be passed to the group callback when all	929	Set the result value(s) that will be passed to the group callback when all
644	subrequests have finished. By default, no argument will be passed.	930	subrequests have finished and set thre groups errno to the current value
		931	of errno (just like calling C<errno> without an error number). By default,
		932	no argument will be passed and errno is zero.
645		933
646	=item $grp->set_feeder ($callback->($grp))	934	=item $grp->errno ([$errno])
647		935
648	[VERY EXPERIMENTAL]	936	Sets the group errno value to C<$errno>, or the current value of errno
		937	when the argument is missing.
		938
		939	Every aio request has an associated errno value that is restored when
		940	the callback is invoked. This method lets you change this value from its
		941	default (0).
		942
		943	Calling C<result> will also set errno, so make sure you either set C<$!>
		944	before the call to C<result>, or call c<errno> after it.
		945
		946	=item feed $grp $callback->($grp)
649		947
650	Sets a feeder/generator on this group: every group can have an attached	948	Sets a feeder/generator on this group: every group can have an attached
651	generator that generates requests if idle. The idea behind this is that,	949	generator that generates requests if idle. The idea behind this is that,
652	although you could just queue as many requests as you want in a group,	950	although you could just queue as many requests as you want in a group,
653	this might starve other requests for a potentially long time. For	951	this might starve other requests for a potentially long time. For
654	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	952	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
655	requests, delaying any later requests for a long time.	953	requests, delaying any later requests for a long time.
656		954
657	To avoid this, and allow incremental generation of requests, you can	955	To avoid this, and allow incremental generation of requests, you can
658	instead a group and set a feeder on it that generates those requests. The	956	instead a group and set a feeder on it that generates those requests. The
659	feeder will be called whenever there are few enough (see C<feeder_limit>,	957	feed callback will be called whenever there are few enough (see C<limit>,
660	below) requests active in the group itself and is expected to queue more	958	below) requests active in the group itself and is expected to queue more
661	requests.	959	requests.
662		960
663	The feeder can queue as many requests as it likes (i.e. C<add> does not	961	The feed callback can queue as many requests as it likes (i.e. C<add> does
664	impose any limits).	962	not impose any limits).
665		963
666	If the feeder does not queue more requests when called, it will be	964	If the feed does not queue more requests when called, it will be
667	automatically removed from the group.	965	automatically removed from the group.
668		966
669	If the feeder limit is C<0>, it will be set to C<2> automatically.	967	If the feed limit is C<0>, it will be set to C<2> automatically.
670		968
671	Example:	969	Example:
672		970
673	# stat all files in @files, but only ever use four aio requests concurrently:	971	# stat all files in @files, but only ever use four aio requests concurrently:
674		972
675	my $grp = aio_group sub { print "finished\n" };	973	my $grp = aio_group sub { print "finished\n" };
676	$grp->feeder_limit (4);	974	limit $grp 4;
677	$grp->set_feeder (sub {	975	feed $grp sub {
678	my $file = pop @files	976	my $file = pop @files
679	or return;	977	or return;
680		978
681	add $grp aio_stat $file, sub { ... };	979	add $grp aio_stat $file, sub { ... };
682	});	980	};
683		981
684	=item $grp->feeder_limit ($num)	982	=item limit $grp $num
685		983
686	Sets the feeder limit for the group: The feeder will be called whenever	984	Sets the feeder limit for the group: The feeder will be called whenever
687	the group contains less than this many requests.	985	the group contains less than this many requests.
688		986
689	Setting the limit to C<0> will pause the feeding process.	987	Setting the limit to C<0> will pause the feeding process.
690		988
691	=back	989	=back
692		990
693	=head2 SUPPORT FUNCTIONS	991	=head2 SUPPORT FUNCTIONS
		992
		993	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
694		994
695	=over 4	995	=over 4
696		996
697	=item $fileno = IO::AIO::poll_fileno	997	=item $fileno = IO::AIO::poll_fileno
698		998
…		…
703		1003
704	See C<poll_cb> for an example.	1004	See C<poll_cb> for an example.
705		1005
706	=item IO::AIO::poll_cb	1006	=item IO::AIO::poll_cb
707		1007
708	Process all outstanding events on the result pipe. You have to call this	1008	Process some outstanding events on the result pipe. You have to call this
709	regularly. Returns the number of events processed. Returns immediately	1009	regularly. Returns the number of events processed. Returns immediately
710	when no events are outstanding.	1010	when no events are outstanding. The amount of events processed depends on
		1011	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1012
		1013	If not all requests were processed for whatever reason, the filehandle
		1014	will still be ready when C<poll_cb> returns.
711		1015
712	Example: Install an Event watcher that automatically calls	1016	Example: Install an Event watcher that automatically calls
713	IO::AIO::poll_cb with high priority:	1017	IO::AIO::poll_cb with high priority:
714		1018
715	Event->io (fd => IO::AIO::poll_fileno,	1019	Event->io (fd => IO::AIO::poll_fileno,
716	poll => 'r', async => 1,	1020	poll => 'r', async => 1,
717	cb => \&IO::AIO::poll_cb);	1021	cb => \&IO::AIO::poll_cb);
718		1022
		1023	=item IO::AIO::max_poll_reqs $nreqs
		1024
		1025	=item IO::AIO::max_poll_time $seconds
		1026
		1027	These set the maximum number of requests (default C<0>, meaning infinity)
		1028	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1029	the maximum amount of time (default C<0>, meaning infinity) spent in
		1030	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1031	of time C<poll_cb> is allowed to use).
		1032
		1033	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1034	syscall per request processed, which is not normally a problem unless your
		1035	callbacks are really really fast or your OS is really really slow (I am
		1036	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1037
		1038	Setting these is useful if you want to ensure some level of
		1039	interactiveness when perl is not fast enough to process all requests in
		1040	time.
		1041
		1042	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1043
		1044	Example: Install an Event watcher that automatically calls
		1045	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1046	program get the CPU sometimes even under high AIO load.
		1047
		1048	# try not to spend much more than 0.1s in poll_cb
		1049	IO::AIO::max_poll_time 0.1;
		1050
		1051	# use a low priority so other tasks have priority
		1052	Event->io (fd => IO::AIO::poll_fileno,
		1053	poll => 'r', nice => 1,
		1054	cb => &IO::AIO::poll_cb);
		1055
719	=item IO::AIO::poll_wait	1056	=item IO::AIO::poll_wait
720		1057
		1058	If there are any outstanding requests and none of them in the result
721	Wait till the result filehandle becomes ready for reading (simply does a	1059	phase, wait till the result filehandle becomes ready for reading (simply
722	C<select> on the filehandle. This is useful if you want to synchronously wait	1060	does a C<select> on the filehandle. This is useful if you want to
723	for some requests to finish).	1061	synchronously wait for some requests to finish).
724		1062
725	See C<nreqs> for an example.	1063	See C<nreqs> for an example.
726		1064
		1065	=item IO::AIO::poll
		1066
		1067	Waits until some requests have been handled.
		1068
		1069	Returns the number of requests processed, but is otherwise strictly
		1070	equivalent to:
		1071
		1072	IO::AIO::poll_wait, IO::AIO::poll_cb
		1073
727	=item IO::AIO::nreqs	1074	=item IO::AIO::flush
728		1075
729	Returns the number of requests currently outstanding (i.e. for which their	1076	Wait till all outstanding AIO requests have been handled.
730	callback has not been invoked yet).
731		1077
732	Example: wait till there are no outstanding requests anymore:	1078	Strictly equivalent to:
733		1079
734	IO::AIO::poll_wait, IO::AIO::poll_cb	1080	IO::AIO::poll_wait, IO::AIO::poll_cb
735	while IO::AIO::nreqs;	1081	while IO::AIO::nreqs;
736		1082
737	=item IO::AIO::flush	1083	=back
738		1084
739	Wait till all outstanding AIO requests have been handled.	1085	=head3 CONTROLLING THE NUMBER OF THREADS
740		1086
741	Strictly equivalent to:	1087	=over
742
743	IO::AIO::poll_wait, IO::AIO::poll_cb
744	while IO::AIO::nreqs;
745
746	=item IO::AIO::poll
747
748	Waits until some requests have been handled.
749
750	Strictly equivalent to:
751
752	IO::AIO::poll_wait, IO::AIO::poll_cb
753	if IO::AIO::nreqs;
754		1088
755	=item IO::AIO::min_parallel $nthreads	1089	=item IO::AIO::min_parallel $nthreads
756		1090
757	Set the minimum number of AIO threads to C<$nthreads>. The current	1091	Set the minimum number of AIO threads to C<$nthreads>. The current
758	default is C<8>, which means eight asynchronous operations can execute	1092	default is C<8>, which means eight asynchronous operations can execute
759	concurrently at any one time (the number of outstanding requests,	1093	concurrently at any one time (the number of outstanding requests,
760	however, is unlimited).	1094	however, is unlimited).
761		1095
762	IO::AIO starts threads only on demand, when an AIO request is queued and	1096	IO::AIO starts threads only on demand, when an AIO request is queued and
763	no free thread exists.	1097	no free thread exists. Please note that queueing up a hundred requests can
		1098	create demand for a hundred threads, even if it turns out that everything
		1099	is in the cache and could have been processed faster by a single thread.
764		1100
765	It is recommended to keep the number of threads relatively low, as some	1101	It is recommended to keep the number of threads relatively low, as some
766	Linux kernel versions will scale negatively with the number of threads	1102	Linux kernel versions will scale negatively with the number of threads
767	(higher parallelity => MUCH higher latency). With current Linux 2.6	1103	(higher parallelity => MUCH higher latency). With current Linux 2.6
768	versions, 4-32 threads should be fine.	1104	versions, 4-32 threads should be fine.
…		…
782	This module automatically runs C<max_parallel 0> at program end, to ensure	1118	This module automatically runs C<max_parallel 0> at program end, to ensure
783	that all threads are killed and that there are no outstanding requests.	1119	that all threads are killed and that there are no outstanding requests.
784		1120
785	Under normal circumstances you don't need to call this function.	1121	Under normal circumstances you don't need to call this function.
786		1122
		1123	=item IO::AIO::max_idle $nthreads
		1124
		1125	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1126	threads that did not get a request to process within 10 seconds). That
		1127	means if a thread becomes idle while C<$nthreads> other threads are also
		1128	idle, it will free its resources and exit.
		1129
		1130	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1131	to allow for extremely high load situations, but want to free resources
		1132	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1133
		1134	The default is probably ok in most situations, especially if thread
		1135	creation is fast. If thread creation is very slow on your system you might
		1136	want to use larger values.
		1137
787	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1138	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1139
		1140	This is a very bad function to use in interactive programs because it
		1141	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1142	use an C<aio_group> together with a feed callback.
788		1143
789	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1144	Sets the maximum number of outstanding requests to C<$nreqs>. If you
790	try to queue up more than this number of requests, the caller will block until	1145	to queue up more than this number of requests, the next call to the
791	some requests have been handled.	1146	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1147	function will block until the limit is no longer exceeded.
792		1148
793	The default is very large, so normally there is no practical limit. If you	1149	The default value is very large, so there is no practical limit on the
794	queue up many requests in a loop it often improves speed if you set	1150	number of outstanding requests.
795	this to a relatively low number, such as C<100>.
796		1151
797	Under normal circumstances you don't need to call this function.	1152	You can still queue as many requests as you want. Therefore,
		1153	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1154	as a stop gap to shield against fatal memory overflow (with large values).
		1155
		1156	=back
		1157
		1158	=head3 STATISTICAL INFORMATION
		1159
		1160	=over
		1161
		1162	=item IO::AIO::nreqs
		1163
		1164	Returns the number of requests currently in the ready, execute or pending
		1165	states (i.e. for which their callback has not been invoked yet).
		1166
		1167	Example: wait till there are no outstanding requests anymore:
		1168
		1169	IO::AIO::poll_wait, IO::AIO::poll_cb
		1170	while IO::AIO::nreqs;
		1171
		1172	=item IO::AIO::nready
		1173
		1174	Returns the number of requests currently in the ready state (not yet
		1175	executed).
		1176
		1177	=item IO::AIO::npending
		1178
		1179	Returns the number of requests currently in the pending state (executed,
		1180	but not yet processed by poll_cb).
798		1181
799	=back	1182	=back
800		1183
801	=cut	1184	=cut
802		1185
…		…
816	*$sym	1199	*$sym
817	}	1200	}
818		1201
819	min_parallel 8;	1202	min_parallel 8;
820		1203
821	END {	1204	END { flush }
822	max_parallel 0;
823	}
824		1205
825	1;	1206	1;
826		1207
827	=head2 FORK BEHAVIOUR	1208	=head2 FORK BEHAVIOUR
828		1209
829	This module should do "the right thing" when the process using it forks:	1210	This module should do "the right thing" when the process using it forks:
830		1211
831	Before the fork, IO::AIO enters a quiescent state where no requests	1212	Before the fork, IO::AIO enters a quiescent state where no requests
832	can be added in other threads and no results will be processed. After	1213	can be added in other threads and no results will be processed. After
833	the fork the parent simply leaves the quiescent state and continues	1214	the fork the parent simply leaves the quiescent state and continues
834	request/result processing, while the child clears the request/result	1215	request/result processing, while the child frees the request/result queue
835	queue (so the requests started before the fork will only be handled in	1216	(so that the requests started before the fork will only be handled in the
836	the parent). Threads will be started on demand until the limit ste in the	1217	parent). Threads will be started on demand until the limit set in the
837	parent process has been reached again.	1218	parent process has been reached again.
838		1219
839	In short: the parent will, after a short pause, continue as if fork had	1220	In short: the parent will, after a short pause, continue as if fork had
840	not been called, while the child will act as if IO::AIO has not been used	1221	not been called, while the child will act as if IO::AIO has not been used
841	yet.	1222	yet.
842		1223
843	=head2 MEMORY USAGE	1224	=head2 MEMORY USAGE
844		1225
		1226	Per-request usage:
		1227
845	Each aio request uses - depending on your architecture - around 128 bytes	1228	Each aio request uses - depending on your architecture - around 100-200
846	of memory. In addition, stat requests need a stat buffer (possibly a few	1229	bytes of memory. In addition, stat requests need a stat buffer (possibly
847	hundred bytes). Perl scalars and other data passed into aio requests will	1230	a few hundred bytes), readdir requires a result buffer and so on. Perl
848	also be locked.	1231	scalars and other data passed into aio requests will also be locked and
		1232	will consume memory till the request has entered the done state.
849		1233
850	This is now awfully much, so queuing lots of requests is not usually a	1234	This is now awfully much, so queuing lots of requests is not usually a
851	problem.	1235	problem.
852		1236
853	Each thread needs a stack area which is usually around 16k, sometimes much	1237	Per-thread usage:
854	larger, depending on the OS.	1238
		1239	In the execution phase, some aio requests require more memory for
		1240	temporary buffers, and each thread requires a stack and other data
		1241	structures (usually around 16k-128k, depending on the OS).
		1242
		1243	=head1 KNOWN BUGS
		1244
		1245	Known bugs will be fixed in the next release.
855		1246
856	=head1 SEE ALSO	1247	=head1 SEE ALSO
857		1248
858	L<Coro>, L<Linux::AIO> (obsolete).	1249	L<Coro::AIO>.
859		1250
860	=head1 AUTHOR	1251	=head1 AUTHOR
861		1252
862	Marc Lehmann <schmorp@schmorp.de>	1253	Marc Lehmann <schmorp@schmorp.de>
863	http://home.schmorp.de/	1254	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.61 by root, Sun Oct 22 13:52:11 2006 UTC vs. Revision 1.105 by root, Sun Mar 25 00:20:27 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.61 by root, Sun Oct 22 13:52:11 2006 UTC vs.
Revision 1.105 by root, Sun Mar 25 00:20:27 2007 UTC