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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.67 by root, Tue Oct 24 02:25:16 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 perl, and	75	requests and signal their completion. You don't need thread support
57	the threads created by this module will not be visible to perl. In the	76	in perl, and the threads created by this module will not be visible
58	future, this module might make use of the native aio functions available	77	to perl. In the future, this module might make use of the native aio
59	on many operating systems. However, they are often not well-supported	78	functions available on many operating systems. However, they are often
60	(Linux doesn't allow them on normal files currently, for example),	79	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	and they would only support aio_read and aio_write, so the remaining	80	files currently, for example), and they would only support aio_read and
62	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 @AIO_REQ = 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 aio_nop);	200	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir);
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	min_parallel max_parallel max_outstanding nreqs);	203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
88		206
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		208
91	require XSLoader;	209	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
93	}	211	}
94		212
95	=head1 FUNCTIONS	213	=head1 FUNCTIONS
96		214
97	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
98		216
99	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
100	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
101	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
102	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
…		…
105	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
106		224
107	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
108	internally until the request has finished.	226	internally until the request has finished.
109		227
110	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
111	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
112		230
113	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
114	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
115	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
116	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
117	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
118		237
119	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
120	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
121	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
122	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
123	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)
124	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.
125		247
126	=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.
127		280
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	281	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		282
130	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
131	created filehandle for the file.	284	created filehandle for the file.
…		…
137	list. They are the same as used by C<sysopen>.	290	list. They are the same as used by C<sysopen>.
138		291
139	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
140	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>,
141	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,
142	and C<0666> or C<0777> if you do).	295	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		296	by the umask in effect then the request is being executed, so better never
		297	change the umask.
143		298
144	Example:	299	Example:
145		300
146	aio_open "/etc/passwd", O_RDONLY, 0, sub {	301	aio_open "/etc/passwd", O_RDONLY, 0, sub {
147	if ($_[0]) {	302	if ($_[0]) {
…		…
182	aio_read $fh, 7, 15, $buffer, 0, sub {	337	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	338	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	339	print "read $_[0] bytes: <$buffer>\n";
185	};	340	};
186		341
187	=item aio_move $srcpath, $dstpath, $callback->($status)
188
189	[EXPERIMENTAL due to internal aio_group use]
190
191	Try to move the I<file> (directories not supported as either source or
192	destination) from C<$srcpath> to C<$dstpath> and call the callback with
193	the C<0> (error) or C<-1> ok.
194
195	This is a composite request that tries to rename(2) the file first. If
196	rename files with C<EXDEV>, it creates the destination file with mode 0200
197	and copies the contents of the source file into it using C<aio_sendfile>,
198	followed by restoring atime, mtime, access mode and uid/gid, in that
199	order, and unlinking the C<$srcpath>.
200
201	If an error occurs, the partial destination file will be unlinked, if
202	possible, except when setting atime, mtime, access mode and uid/gid, where
203	errors are being ignored.
204
205	=cut
206
207	sub aio_move($$$) {
208	my ($src, $dst, $cb) = @_;
209
210	my $grp = aio_group $cb;
211
212	add $grp aio_rename $src, $dst, sub {
213	if ($_[0] && $! == EXDEV) {
214	add $grp aio_open $src, O_RDONLY, 0, sub {
215	if (my $src_fh = $_[0]) {
216	my @stat = stat $src_fh;
217
218	add $grp aio_open $dst, O_WRONLY, 0200, sub {
219	if (my $dst_fh = $_[0]) {
220	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
221	close $src_fh;
222
223	if ($_[0] == $stat[7]) {
224	utime $stat[8], $stat[9], $dst;
225	chmod $stat[2] & 07777, $dst_fh;
226	chown $stat[4], $stat[5], $dst_fh;
227	close $dst_fh;
228
229	add $grp aio_unlink $src, sub {
230	$grp->result ($_[0]);
231	};
232	} else {
233	my $errno = $!;
234	add $grp aio_unlink $dst, sub {
235	$! = $errno;
236	$grp->result (-1);
237	};
238	}
239	};
240	} else {
241	$grp->result (-1);
242	}
243	},
244
245	} else {
246	$grp->result (-1);
247	}
248	};
249	} else {
250	$grp->result ($_[0]);
251	}
252	};
253
254	$grp
255	}
256
257	=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)
258		343
259	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
260	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
261	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
…		…
316	=item aio_unlink $pathname, $callback->($status)	401	=item aio_unlink $pathname, $callback->($status)
317		402
318	Asynchronously unlink (delete) a file and call the callback with the	403	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	404	result code.
320		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
321	=item aio_link $srcpath, $dstpath, $callback->($status)	416	=item aio_link $srcpath, $dstpath, $callback->($status)
322		417
323	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
324	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.
325		420
326	=item aio_symlink $srcpath, $dstpath, $callback->($status)	421	=item aio_symlink $srcpath, $dstpath, $callback->($status)
327		422
328	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
329	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.
330		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
331	=item aio_rename $srcpath, $dstpath, $callback->($status)	432	=item aio_rename $srcpath, $dstpath, $callback->($status)
332		433
333	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
334	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.
335		442
336	=item aio_rmdir $pathname, $callback->($status)	443	=item aio_rmdir $pathname, $callback->($status)
337		444
338	Asynchronously rmdir (delete) a directory and call the callback with the	445	Asynchronously rmdir (delete) a directory and call the callback with the
339	result code.	446	result code.
…		…
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	452	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		453
347	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
348	with the filenames.	455	with the filenames.
349		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
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	593	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		594
352	[EXPERIMENTAL due to internal aio_group use]
353
354	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
355	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
356	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
357	recurse into (everything else).	598	recurse into (everything else, including symlinks to directories).
358		599
359	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_
360	C<$maxreq> specifies the maximum number of outstanding aio requests that	601	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	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
362	will be chosen (currently 6).	603	will be chosen (currently 4).
363		604
364	On error, the callback is called without arguments, otherwise it receives	605	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	606	two array-refs with path-relative entry names.
366		607
367	Example:	608	Example:
…		…
401	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
402	directory counting heuristic.	643	directory counting heuristic.
403		644
404	=cut	645	=cut
405		646
406	sub aio_scandir($$$) {	647	sub aio_scandir($$;$) {
		648	aio_block {
407	my ($path, $maxreq, $cb) = @_;	649	my ($path, $maxreq, $cb) = @_;
408		650
		651	my $pri = aioreq_pri;
		652
409	my $grp = aio_group $cb;	653	my $grp = aio_group $cb;
410		654
411	$maxreq = 6 if $maxreq <= 0;	655	$maxreq = 4 if $maxreq <= 0;
412		656
413	# stat once	657	# stat once
		658	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	659	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	660	return $grp->result () if $_[0];
416	my $now = time;	661	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	662	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		663
419	# read the directory entries	664	# read the directory entries
		665	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	666	add $grp aio_readdir $path, sub {
421	my $entries = shift	667	my $entries = shift
422	or return $grp->result ();	668	or return $grp->result ();
423		669
424	# stat the dir another time	670	# stat the dir another time
		671	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	672	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	673	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		674
428	my $ndirs;	675	my $ndirs;
429		676
430	# take the slow route if anything looks fishy	677	# take the slow route if anything looks fishy
431	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	678	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
432	$ndirs = -1;	679	$ndirs = -1;
433	} else {	680	} else {
434	# if nlink == 2, we are finished	681	# if nlink == 2, we are finished
435	# on non-posix-fs's, we rely on nlink < 2	682	# on non-posix-fs's, we rely on nlink < 2
436	$ndirs = (stat _)[3] - 2	683	$ndirs = (stat _)[3] - 2
437	or return $grp->result ([], $entries);	684	or return $grp->result ([], $entries);
438	}	685	}
439		686
440	# sort into likely dirs and likely nondirs	687	# sort into likely dirs and likely nondirs
441	# dirs == files without ".", short entries first	688	# dirs == files without ".", short entries first
442	$entries = [map $_->[0],	689	$entries = [map $_->[0],
443	sort { $b->[1] cmp $a->[1] }	690	sort { $b->[1] cmp $a->[1] }
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	691	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	692	@$entries];
446		693
447	my (@dirs, @nondirs);	694	my (@dirs, @nondirs);
448		695
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	696	my $statgrp = add $grp aio_group sub {
453
454	$schedcb = sub {
455	if (@$entries) {
456	if ($nreq < $maxreq) {
457	my $ent = pop @$entries;
458	$nreq++;
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);	697	$grp->result (\@dirs, \@nondirs);
467	}	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	};
468	};	727	};
469	$statcb = sub {
470	my ($status, $entry) = @_;
471
472	if ($status < 0) {
473	$nreq--;
474	push @nondirs, $entry;
475	&$schedcb;
476	} else {
477	# need to check for real directory
478	add $grp aio_lstat "$path/$entry", sub {
479	$nreq--;
480
481	if (-d _) {
482	push @dirs, $entry;
483
484	if (!--$ndirs) {
485	push @nondirs, @$entries;
486	$entries = [];
487	}
488	} else {
489	push @nondirs, $entry;
490	}
491
492	&$schedcb;
493	}
494	}
495	};
496
497	&$schedcb while @$entries && $nreq < $maxreq;
498	};	728	};
499	};	729	};
		730
		731	$grp
500	};	732	}
		733	}
501		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
502	$grp	768	$grp
		769	}
503	}	770	}
504		771
505	=item aio_fsync $fh, $callback->($status)	772	=item aio_fsync $fh, $callback->($status)
506		773
507	Asynchronously call fsync on the given filehandle and call the callback	774	Asynchronously call fsync on the given filehandle and call the callback
…		…
515	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
516	detected, it will be emulated by calling C<fsync> instead.	783	detected, it will be emulated by calling C<fsync> instead.
517		784
518	=item aio_group $callback->(...)	785	=item aio_group $callback->(...)
519		786
520	[EXPERIMENTAL]
521
522	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
523	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
524	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.
525		791
526	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
527	for more info.	793	for more info.
528		794
529	Example:	795	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	814	phase and still requires a worker thread. Thus, the callback will not
549	be executed immediately but only after other requests in the queue have	815	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	816	entered their execution phase. This can be used to measure request
551	latency.	817	latency.
552		818
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	819	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		820
555	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
556	the request workers to sleep for the given time.	822	the request workers to sleep for the given time.
557		823
558	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
559	like sleep and file handle readable/writable, the overhead this creates	825	like sleep and file handle readable/writable, the overhead this creates is
560	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
561	under artificial I/O pressure.	827	except to put your application under artificial I/O pressure.
562		828
563	=back	829	=back
564		830
565	=head2 IO::AIO::REQ CLASS	831	=head2 IO::AIO::REQ CLASS
566		832
567	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
568	called in non-void context.	834	called in non-void context.
569
570	A request always moves through the following five states in its lifetime,
571	in order: B<ready> (request has been created, but has not been executed
572	yet), B<execute> (request is currently being executed), B<pending>
573	(request has been executed but callback has not been called yet),
574	B<result> (results are being processed synchronously, includes calling the
575	callback) and B<done> (request has reached the end of its lifetime and
576	holds no resources anymore).
577		835
578	=over 4	836	=over 4
579		837
580	=item cancel $req	838	=item cancel $req
581		839
…		…
635	=item * 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.
636		894
637	=item * 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
638	any later time).	896	any later time).
639		897
640	=item * This does not harmonise well with C<max_outstanding>, so best do
641	not combine C<aio_group> with it. Groups and feeders are recommended for
642	this kind of concurrency-limiting.
643
644	=back	898	=back
645		899
646	Their lifetime, simplified, looks like this: when they are empty, they	900	Their lifetime, simplified, looks like this: when they are empty, they
647	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
648	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
…		…
663	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
664	dependencies.	918	dependencies.
665		919
666	Returns all its arguments.	920	Returns all its arguments.
667		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
668	=item $grp->result (...)	927	=item $grp->result (...)
669		928
670	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
671	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.
		933
		934	=item $grp->errno ([$errno])
		935
		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.
672		945
673	=item feed $grp $callback->($grp)	946	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		947
677	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
678	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,
679	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,
680	this might starve other requests for a potentially long time. For	951	this might starve other requests for a potentially long time. For
681	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>
682	requests, delaying any later requests for a long time.	953	requests, delaying any later requests for a long time.
683		954
684	To avoid this, and allow incremental generation of requests, you can	955	To avoid this, and allow incremental generation of requests, you can
685	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
686	feed callback will be called whenever there are few enough (see C<feed_limit>,	957	feed callback will be called whenever there are few enough (see C<limit>,
687	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
688	requests.	959	requests.
689		960
690	The feed 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
691	impose any limits).	962	not impose any limits).
692		963
693	If the feed does not queue more requests when called, it will be	964	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	965	automatically removed from the group.
695		966
696	If the feed 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.
…		…
698	Example:	969	Example:
699		970
700	# 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:
701		972
702	my $grp = aio_group sub { print "finished\n" };	973	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	974	limit $grp 4;
704	feed $grp sub {	975	feed $grp sub {
705	my $file = pop @files	976	my $file = pop @files
706	or return;	977	or return;
707		978
708	add $grp aio_stat $file, sub { ... };	979	add $grp aio_stat $file, sub { ... };
709	};	980	};
710		981
711	=item feed_limit $grp $num	982	=item limit $grp $num
712		983
713	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
714	the group contains less than this many requests.	985	the group contains less than this many requests.
715		986
716	Setting the limit to C<0> will pause the feeding process.	987	Setting the limit to C<0> will pause the feeding process.
717		988
718	=back	989	=back
719		990
720	=head2 SUPPORT FUNCTIONS	991	=head2 SUPPORT FUNCTIONS
		992
		993	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
721		994
722	=over 4	995	=over 4
723		996
724	=item $fileno = IO::AIO::poll_fileno	997	=item $fileno = IO::AIO::poll_fileno
725		998
…		…
730		1003
731	See C<poll_cb> for an example.	1004	See C<poll_cb> for an example.
732		1005
733	=item IO::AIO::poll_cb	1006	=item IO::AIO::poll_cb
734		1007
735	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
736	regularly. Returns the number of events processed. Returns immediately	1009	regularly. Returns the number of events processed. Returns immediately
737	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.
738		1015
739	Example: Install an Event watcher that automatically calls	1016	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	1017	IO::AIO::poll_cb with high priority:
741		1018
742	Event->io (fd => IO::AIO::poll_fileno,	1019	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	1020	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	1021	cb => \&IO::AIO::poll_cb);
745		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
746	=item IO::AIO::poll_wait	1056	=item IO::AIO::poll_wait
747		1057
		1058	If there are any outstanding requests and none of them in the result
748	Wait till the result filehandle becomes ready for reading (simply does a	1059	phase, wait till the result filehandle becomes ready for reading (simply
749	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
750	for some requests to finish).	1061	synchronously wait for some requests to finish).
751		1062
752	See C<nreqs> for an example.	1063	See C<nreqs> for an example.
753		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
754	=item IO::AIO::nreqs	1074	=item IO::AIO::flush
755		1075
756	Returns the number of requests currently outstanding (i.e. for which their	1076	Wait till all outstanding AIO requests have been handled.
757	callback has not been invoked yet).
758		1077
759	Example: wait till there are no outstanding requests anymore:	1078	Strictly equivalent to:
760		1079
761	IO::AIO::poll_wait, IO::AIO::poll_cb	1080	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	1081	while IO::AIO::nreqs;
763		1082
764	=item IO::AIO::flush	1083	=back
765		1084
766	Wait till all outstanding AIO requests have been handled.	1085	=head3 CONTROLLING THE NUMBER OF THREADS
767		1086
768	Strictly equivalent to:	1087	=over
769
770	IO::AIO::poll_wait, IO::AIO::poll_cb
771	while IO::AIO::nreqs;
772
773	=item IO::AIO::poll
774
775	Waits until some requests have been handled.
776
777	Strictly equivalent to:
778
779	IO::AIO::poll_wait, IO::AIO::poll_cb
780	if IO::AIO::nreqs;
781		1088
782	=item IO::AIO::min_parallel $nthreads	1089	=item IO::AIO::min_parallel $nthreads
783		1090
784	Set the minimum number of AIO threads to C<$nthreads>. The current	1091	Set the minimum number of AIO threads to C<$nthreads>. The current
785	default is C<8>, which means eight asynchronous operations can execute	1092	default is C<8>, which means eight asynchronous operations can execute
786	concurrently at any one time (the number of outstanding requests,	1093	concurrently at any one time (the number of outstanding requests,
787	however, is unlimited).	1094	however, is unlimited).
788		1095
789	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
790	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.
791		1100
792	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
793	Linux kernel versions will scale negatively with the number of threads	1102	Linux kernel versions will scale negatively with the number of threads
794	(higher parallelity => MUCH higher latency). With current Linux 2.6	1103	(higher parallelity => MUCH higher latency). With current Linux 2.6
795	versions, 4-32 threads should be fine.	1104	versions, 4-32 threads should be fine.
…		…
809	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
810	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.
811		1120
812	Under normal circumstances you don't need to call this function.	1121	Under normal circumstances you don't need to call this function.
813		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
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1138	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		1139
816	[DEPRECATED]	1140	This is a very bad function to use in interactive programs because it
		1141	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1142	use an C<aio_group> together with a feed callback.
817		1143
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1144	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	try to queue up more than this number of requests, the caller will block until	1145	to queue up more than this number of requests, the next call to the
820	some requests have been handled.	1146	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1147	function will block until the limit is no longer exceeded.
821		1148
822	The default is very large, so normally there is no practical limit. If you	1149	The default value is very large, so there is no practical limit on the
823	queue up many requests in a loop it often improves speed if you set	1150	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		1151
826	This function does not work well together with C<aio_group>'s, and their	1152	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	1153	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
828	this function.	1154	as a stop gap to shield against fatal memory overflow (with large values).
829		1155
830	Under normal circumstances you don't need to call this function.	1156	=back
		1157
		1158	=head3 STATISTICAL INFORMATION
		1159
		1160	=over
		1161
		1162	=item IO::AIO::nreqs
		1163
		1164	Returns the number of requests currently in the ready, execute or pending
		1165	states (i.e. for which their callback has not been invoked yet).
		1166
		1167	Example: wait till there are no outstanding requests anymore:
		1168
		1169	IO::AIO::poll_wait, IO::AIO::poll_cb
		1170	while IO::AIO::nreqs;
		1171
		1172	=item IO::AIO::nready
		1173
		1174	Returns the number of requests currently in the ready state (not yet
		1175	executed).
		1176
		1177	=item IO::AIO::npending
		1178
		1179	Returns the number of requests currently in the pending state (executed,
		1180	but not yet processed by poll_cb).
831		1181
832	=back	1182	=back
833		1183
834	=cut	1184	=cut
835		1185
…		…
849	*$sym	1199	*$sym
850	}	1200	}
851		1201
852	min_parallel 8;	1202	min_parallel 8;
853		1203
854	END {	1204	END { flush }
855	max_parallel 0;
856	}
857		1205
858	1;	1206	1;
859		1207
860	=head2 FORK BEHAVIOUR	1208	=head2 FORK BEHAVIOUR
861		1209
862	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:
863		1211
864	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
865	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
866	the fork the parent simply leaves the quiescent state and continues	1214	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1215	request/result processing, while the child frees the request/result queue
868	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
869	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
870	parent process has been reached again.	1218	parent process has been reached again.
871		1219
872	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
873	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
874	yet.	1222	yet.
875		1223
876	=head2 MEMORY USAGE	1224	=head2 MEMORY USAGE
877		1225
		1226	Per-request usage:
		1227
878	Each aio request uses - depending on your architecture - around 128 bytes	1228	Each aio request uses - depending on your architecture - around 100-200
879	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
880	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
881	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.
882		1233
883	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
884	problem.	1235	problem.
885		1236
886	Each thread needs a stack area which is usually around 16k, sometimes much	1237	Per-thread usage:
887	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.
888		1246
889	=head1 SEE ALSO	1247	=head1 SEE ALSO
890		1248
891	L<Coro>, L<Linux::AIO> (obsolete).	1249	L<Coro::AIO>.
892		1250
893	=head1 AUTHOR	1251	=head1 AUTHOR
894		1252
895	Marc Lehmann <schmorp@schmorp.de>	1253	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1254	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.67 by root, Tue Oct 24 02:25:16 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 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.105 by root, Sun Mar 25 00:20:27 2007 UTC