[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 1.100 by root, Sun Jan 7 21:36:58 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 = '2.32';
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);
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.
…		…
182	aio_read $fh, 7, 15, $buffer, 0, sub {	335	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	336	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	337	print "read $_[0] bytes: <$buffer>\n";
185	};	338	};
186		339
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)	340	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
258		341
259	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	342	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	343	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	344	file offset of C<$out_fh>. Because of that, it is not safe to issue more
…		…
316	=item aio_unlink $pathname, $callback->($status)	399	=item aio_unlink $pathname, $callback->($status)
317		400
318	Asynchronously unlink (delete) a file and call the callback with the	401	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	402	result code.
320		403
		404	=item aio_mknod $path, $mode, $dev, $callback->($status)
		405
		406	[EXPERIMENTAL]
		407
		408	Asynchronously create a device node (or fifo). See mknod(2).
		409
		410	The only (POSIX-) portable way of calling this function is:
		411
		412	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		413
321	=item aio_link $srcpath, $dstpath, $callback->($status)	414	=item aio_link $srcpath, $dstpath, $callback->($status)
322		415
323	Asynchronously create a new link to the existing object at C<$srcpath> at	416	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.	417	the path C<$dstpath> and call the callback with the result code.
325		418
326	=item aio_symlink $srcpath, $dstpath, $callback->($status)	419	=item aio_symlink $srcpath, $dstpath, $callback->($status)
327		420
328	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	421	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.	422	the path C<$dstpath> and call the callback with the result code.
		423
		424	=item aio_readlink $path, $callback->($link)
		425
		426	Asynchronously read the symlink specified by C<$path> and pass it to
		427	the callback. If an error occurs, nothing or undef gets passed to the
		428	callback.
330		429
331	=item aio_rename $srcpath, $dstpath, $callback->($status)	430	=item aio_rename $srcpath, $dstpath, $callback->($status)
332		431
333	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	432	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
334	rename(2) and call the callback with the result code.	433	rename(2) and call the callback with the result code.
…		…
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	444	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		445
347	The callback a single argument which is either C<undef> or an array-ref	446	The callback a single argument which is either C<undef> or an array-ref
348	with the filenames.	447	with the filenames.
349		448
		449	=item aio_load $path, $data, $callback->($status)
		450
		451	This is a composite request that tries to fully load the given file into
		452	memory. Status is the same as with aio_read.
		453
		454	=cut
		455
		456	sub aio_load($$;$) {
		457	aio_block {
		458	my ($path, undef, $cb) = @_;
		459	my $data = \$_[1];
		460
		461	my $pri = aioreq_pri;
		462	my $grp = aio_group $cb;
		463
		464	aioreq_pri $pri;
		465	add $grp aio_open $path, O_RDONLY, 0, sub {
		466	my ($fh) = @_
		467	or return $grp->result (-1);
		468
		469	aioreq_pri $pri;
		470	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		471	$grp->result ($_[0]);
		472	};
		473	};
		474
		475	$grp
		476	}
		477	}
		478
		479	=item aio_copy $srcpath, $dstpath, $callback->($status)
		480
		481	Try to copy the I<file> (directories not supported as either source or
		482	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		483	the C<0> (error) or C<-1> ok.
		484
		485	This is a composite request that it creates the destination file with
		486	mode 0200 and copies the contents of the source file into it using
		487	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		488	uid/gid, in that order.
		489
		490	If an error occurs, the partial destination file will be unlinked, if
		491	possible, except when setting atime, mtime, access mode and uid/gid, where
		492	errors are being ignored.
		493
		494	=cut
		495
		496	sub aio_copy($$;$) {
		497	aio_block {
		498	my ($src, $dst, $cb) = @_;
		499
		500	my $pri = aioreq_pri;
		501	my $grp = aio_group $cb;
		502
		503	aioreq_pri $pri;
		504	add $grp aio_open $src, O_RDONLY, 0, sub {
		505	if (my $src_fh = $_[0]) {
		506	my @stat = stat $src_fh;
		507
		508	aioreq_pri $pri;
		509	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		510	if (my $dst_fh = $_[0]) {
		511	aioreq_pri $pri;
		512	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		513	if ($_[0] == $stat[7]) {
		514	$grp->result (0);
		515	close $src_fh;
		516
		517	# those should not normally block. should. should.
		518	utime $stat[8], $stat[9], $dst;
		519	chmod $stat[2] & 07777, $dst_fh;
		520	chown $stat[4], $stat[5], $dst_fh;
		521	close $dst_fh;
		522	} else {
		523	$grp->result (-1);
		524	close $src_fh;
		525	close $dst_fh;
		526
		527	aioreq $pri;
		528	add $grp aio_unlink $dst;
		529	}
		530	};
		531	} else {
		532	$grp->result (-1);
		533	}
		534	},
		535
		536	} else {
		537	$grp->result (-1);
		538	}
		539	};
		540
		541	$grp
		542	}
		543	}
		544
		545	=item aio_move $srcpath, $dstpath, $callback->($status)
		546
		547	Try to move the I<file> (directories not supported as either source or
		548	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		549	the C<0> (error) or C<-1> ok.
		550
		551	This is a composite request that tries to rename(2) the file first. If
		552	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		553	that is successful, unlinking the C<$srcpath>.
		554
		555	=cut
		556
		557	sub aio_move($$;$) {
		558	aio_block {
		559	my ($src, $dst, $cb) = @_;
		560
		561	my $pri = aioreq_pri;
		562	my $grp = aio_group $cb;
		563
		564	aioreq_pri $pri;
		565	add $grp aio_rename $src, $dst, sub {
		566	if ($_[0] && $! == EXDEV) {
		567	aioreq_pri $pri;
		568	add $grp aio_copy $src, $dst, sub {
		569	$grp->result ($_[0]);
		570
		571	if (!$_[0]) {
		572	aioreq_pri $pri;
		573	add $grp aio_unlink $src;
		574	}
		575	};
		576	} else {
		577	$grp->result ($_[0]);
		578	}
		579	};
		580
		581	$grp
		582	}
		583	}
		584
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	585	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		586
352	[EXPERIMENTAL due to internal aio_group use]
353
354	Scans a directory (similar to C<aio_readdir>) but additionally tries to	587	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	588	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	589	names, directories you can recurse into (directories), and ones you cannot
357	recurse into (everything else).	590	recurse into (everything else, including symlinks to directories).
358		591
359	C<aio_scandir> is a composite request that creates of many sub requests_	592	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	593	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	this function generates. If it is C<< <= 0 >>, then a suitable default	594	this function generates. If it is C<< <= 0 >>, then a suitable default
362	will be chosen (currently 6).	595	will be chosen (currently 4).
363		596
364	On error, the callback is called without arguments, otherwise it receives	597	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	598	two array-refs with path-relative entry names.
366		599
367	Example:	600	Example:
…		…
401	as those tend to return 0 or 1 as link counts, which disables the	634	as those tend to return 0 or 1 as link counts, which disables the
402	directory counting heuristic.	635	directory counting heuristic.
403		636
404	=cut	637	=cut
405		638
406	sub aio_scandir($$$) {	639	sub aio_scandir($$;$) {
		640	aio_block {
407	my ($path, $maxreq, $cb) = @_;	641	my ($path, $maxreq, $cb) = @_;
408		642
		643	my $pri = aioreq_pri;
		644
409	my $grp = aio_group $cb;	645	my $grp = aio_group $cb;
410		646
411	$maxreq = 6 if $maxreq <= 0;	647	$maxreq = 4 if $maxreq <= 0;
412		648
413	# stat once	649	# stat once
		650	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	651	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	652	return $grp->result () if $_[0];
416	my $now = time;	653	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	654	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		655
419	# read the directory entries	656	# read the directory entries
		657	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	658	add $grp aio_readdir $path, sub {
421	my $entries = shift	659	my $entries = shift
422	or return $grp->result ();	660	or return $grp->result ();
423		661
424	# stat the dir another time	662	# stat the dir another time
		663	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	664	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	665	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		666
428	my $ndirs;	667	my $ndirs;
429		668
430	# take the slow route if anything looks fishy	669	# take the slow route if anything looks fishy
431	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	670	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
432	$ndirs = -1;	671	$ndirs = -1;
433	} else {	672	} else {
434	# if nlink == 2, we are finished	673	# if nlink == 2, we are finished
435	# on non-posix-fs's, we rely on nlink < 2	674	# on non-posix-fs's, we rely on nlink < 2
436	$ndirs = (stat _)[3] - 2	675	$ndirs = (stat _)[3] - 2
437	or return $grp->result ([], $entries);	676	or return $grp->result ([], $entries);
438	}	677	}
439		678
440	# sort into likely dirs and likely nondirs	679	# sort into likely dirs and likely nondirs
441	# dirs == files without ".", short entries first	680	# dirs == files without ".", short entries first
442	$entries = [map $_->[0],	681	$entries = [map $_->[0],
443	sort { $b->[1] cmp $a->[1] }	682	sort { $b->[1] cmp $a->[1] }
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	683	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	684	@$entries];
446		685
447	my (@dirs, @nondirs);	686	my (@dirs, @nondirs);
448		687
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	688	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);	689	$grp->result (\@dirs, \@nondirs);
467	}	690	};
		691
		692	limit $statgrp $maxreq;
		693	feed $statgrp sub {
		694	return unless @$entries;
		695	my $entry = pop @$entries;
		696
		697	aioreq_pri $pri;
		698	add $statgrp aio_stat "$path/$entry/.", sub {
		699	if ($_[0] < 0) {
		700	push @nondirs, $entry;
		701	} else {
		702	# need to check for real directory
		703	aioreq_pri $pri;
		704	add $statgrp aio_lstat "$path/$entry", sub {
		705	if (-d _) {
		706	push @dirs, $entry;
		707
		708	unless (--$ndirs) {
		709	push @nondirs, @$entries;
		710	feed $statgrp;
		711	}
		712	} else {
		713	push @nondirs, $entry;
		714	}
		715	}
		716	}
		717	};
		718	};
468	};	719	};
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	};	720	};
499	};	721	};
		722
		723	$grp
500	};	724	}
		725	}
501		726
		727	=item aio_rmtree $path, $callback->($status)
		728
		729	Delete a directory tree starting (and including) C<$path>, return the
		730	status of the final C<rmdir> only. This is a composite request that
		731	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		732	everything else.
		733
		734	=cut
		735
		736	sub aio_rmtree;
		737	sub aio_rmtree($;$) {
		738	aio_block {
		739	my ($path, $cb) = @_;
		740
		741	my $pri = aioreq_pri;
		742	my $grp = aio_group $cb;
		743
		744	aioreq_pri $pri;
		745	add $grp aio_scandir $path, 0, sub {
		746	my ($dirs, $nondirs) = @_;
		747
		748	my $dirgrp = aio_group sub {
		749	add $grp aio_rmdir $path, sub {
		750	$grp->result ($_[0]);
		751	};
		752	};
		753
		754	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		755	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		756
		757	add $grp $dirgrp;
		758	};
		759
502	$grp	760	$grp
		761	}
503	}	762	}
504		763
505	=item aio_fsync $fh, $callback->($status)	764	=item aio_fsync $fh, $callback->($status)
506		765
507	Asynchronously call fsync on the given filehandle and call the callback	766	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	774	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.	775	detected, it will be emulated by calling C<fsync> instead.
517		776
518	=item aio_group $callback->(...)	777	=item aio_group $callback->(...)
519		778
520	[EXPERIMENTAL]
521
522	This is a very special aio request: Instead of doing something, it is a	779	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	780	container for other aio requests, which is useful if you want to bundle
524	many requests into a single, composite, request.	781	many requests into a single, composite, request with a definite callback
		782	and the ability to cancel the whole request with its subrequests.
525		783
526	Returns an object of class L<IO::AIO::GRP>. See its documentation below	784	Returns an object of class L<IO::AIO::GRP>. See its documentation below
527	for more info.	785	for more info.
528		786
529	Example:	787	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	806	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	807	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	808	entered their execution phase. This can be used to measure request
551	latency.	809	latency.
552		810
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	811	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		812
555	Mainly used for debugging and benchmarking, this aio request puts one of	813	Mainly used for debugging and benchmarking, this aio request puts one of
556	the request workers to sleep for the given time.	814	the request workers to sleep for the given time.
557		815
558	While it is theoretically handy to have simple I/O scheduling requests	816	While it is theoretically handy to have simple I/O scheduling requests
559	like sleep and file handle readable/writable, the overhead this creates	817	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	818	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	819	except to put your application under artificial I/O pressure.
562		820
563	=back	821	=back
564		822
565	=head2 IO::AIO::REQ CLASS	823	=head2 IO::AIO::REQ CLASS
566		824
567	All non-aggregate C<aio_*> functions return an object of this class when	825	All non-aggregate C<aio_*> functions return an object of this class when
568	called in non-void context.	826	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		827
578	=over 4	828	=over 4
579		829
580	=item cancel $req	830	=item cancel $req
581		831
…		…
635	=item * They can also can also be added to other IO::AIO::GRP objects.	885	=item * They can also can also be added to other IO::AIO::GRP objects.
636		886
637	=item * You must not add requests to a group from within the group callback (or	887	=item * You must not add requests to a group from within the group callback (or
638	any later time).	888	any later time).
639		889
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	890	=back
645		891
646	Their lifetime, simplified, looks like this: when they are empty, they	892	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	893	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	894	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	909	be added, including other groups, as long as you do not create circular
664	dependencies.	910	dependencies.
665		911
666	Returns all its arguments.	912	Returns all its arguments.
667		913
		914	=item $grp->cancel_subs
		915
		916	Cancel all subrequests and clears any feeder, but not the group request
		917	itself. Useful when you queued a lot of events but got a result early.
		918
668	=item $grp->result (...)	919	=item $grp->result (...)
669		920
670	Set the result value(s) that will be passed to the group callback when all	921	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.	922	subrequests have finished and set thre groups errno to the current value
		923	of errno (just like calling C<errno> without an error number). By default,
		924	no argument will be passed and errno is zero.
		925
		926	=item $grp->errno ([$errno])
		927
		928	Sets the group errno value to C<$errno>, or the current value of errno
		929	when the argument is missing.
		930
		931	Every aio request has an associated errno value that is restored when
		932	the callback is invoked. This method lets you change this value from its
		933	default (0).
		934
		935	Calling C<result> will also set errno, so make sure you either set C<$!>
		936	before the call to C<result>, or call c<errno> after it.
672		937
673	=item feed $grp $callback->($grp)	938	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		939
677	Sets a feeder/generator on this group: every group can have an attached	940	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,	941	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,	942	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	943	this might starve other requests for a potentially long time. For
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	944	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
682	requests, delaying any later requests for a long time.	945	requests, delaying any later requests for a long time.
683		946
684	To avoid this, and allow incremental generation of requests, you can	947	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	948	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>,	949	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	950	below) requests active in the group itself and is expected to queue more
688	requests.	951	requests.
689		952
690	The feed can queue as many requests as it likes (i.e. C<add> does not	953	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	954	not impose any limits).
692		955
693	If the feed does not queue more requests when called, it will be	956	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	957	automatically removed from the group.
695		958
696	If the feed limit is C<0>, it will be set to C<2> automatically.	959	If the feed limit is C<0>, it will be set to C<2> automatically.
…		…
698	Example:	961	Example:
699		962
700	# stat all files in @files, but only ever use four aio requests concurrently:	963	# stat all files in @files, but only ever use four aio requests concurrently:
701		964
702	my $grp = aio_group sub { print "finished\n" };	965	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	966	limit $grp 4;
704	feed $grp sub {	967	feed $grp sub {
705	my $file = pop @files	968	my $file = pop @files
706	or return;	969	or return;
707		970
708	add $grp aio_stat $file, sub { ... };	971	add $grp aio_stat $file, sub { ... };
709	};	972	};
710		973
711	=item feed_limit $grp $num	974	=item limit $grp $num
712		975
713	Sets the feeder limit for the group: The feeder will be called whenever	976	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	977	the group contains less than this many requests.
715		978
716	Setting the limit to C<0> will pause the feeding process.	979	Setting the limit to C<0> will pause the feeding process.
717		980
718	=back	981	=back
719		982
720	=head2 SUPPORT FUNCTIONS	983	=head2 SUPPORT FUNCTIONS
		984
		985	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
721		986
722	=over 4	987	=over 4
723		988
724	=item $fileno = IO::AIO::poll_fileno	989	=item $fileno = IO::AIO::poll_fileno
725		990
…		…
730		995
731	See C<poll_cb> for an example.	996	See C<poll_cb> for an example.
732		997
733	=item IO::AIO::poll_cb	998	=item IO::AIO::poll_cb
734		999
735	Process all outstanding events on the result pipe. You have to call this	1000	Process some outstanding events on the result pipe. You have to call this
736	regularly. Returns the number of events processed. Returns immediately	1001	regularly. Returns the number of events processed. Returns immediately
737	when no events are outstanding.	1002	when no events are outstanding. The amount of events processed depends on
		1003	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1004
		1005	If not all requests were processed for whatever reason, the filehandle
		1006	will still be ready when C<poll_cb> returns.
738		1007
739	Example: Install an Event watcher that automatically calls	1008	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	1009	IO::AIO::poll_cb with high priority:
741		1010
742	Event->io (fd => IO::AIO::poll_fileno,	1011	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	1012	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	1013	cb => \&IO::AIO::poll_cb);
745		1014
		1015	=item IO::AIO::max_poll_reqs $nreqs
		1016
		1017	=item IO::AIO::max_poll_time $seconds
		1018
		1019	These set the maximum number of requests (default C<0>, meaning infinity)
		1020	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1021	the maximum amount of time (default C<0>, meaning infinity) spent in
		1022	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1023	of time C<poll_cb> is allowed to use).
		1024
		1025	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1026	syscall per request processed, which is not normally a problem unless your
		1027	callbacks are really really fast or your OS is really really slow (I am
		1028	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1029
		1030	Setting these is useful if you want to ensure some level of
		1031	interactiveness when perl is not fast enough to process all requests in
		1032	time.
		1033
		1034	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1035
		1036	Example: Install an Event watcher that automatically calls
		1037	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1038	program get the CPU sometimes even under high AIO load.
		1039
		1040	# try not to spend much more than 0.1s in poll_cb
		1041	IO::AIO::max_poll_time 0.1;
		1042
		1043	# use a low priority so other tasks have priority
		1044	Event->io (fd => IO::AIO::poll_fileno,
		1045	poll => 'r', nice => 1,
		1046	cb => &IO::AIO::poll_cb);
		1047
746	=item IO::AIO::poll_wait	1048	=item IO::AIO::poll_wait
747		1049
		1050	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	1051	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	1052	does a C<select> on the filehandle. This is useful if you want to
750	for some requests to finish).	1053	synchronously wait for some requests to finish).
751		1054
752	See C<nreqs> for an example.	1055	See C<nreqs> for an example.
753		1056
		1057	=item IO::AIO::poll
		1058
		1059	Waits until some requests have been handled.
		1060
		1061	Returns the number of requests processed, but is otherwise strictly
		1062	equivalent to:
		1063
		1064	IO::AIO::poll_wait, IO::AIO::poll_cb
		1065
754	=item IO::AIO::nreqs	1066	=item IO::AIO::flush
755		1067
756	Returns the number of requests currently outstanding (i.e. for which their	1068	Wait till all outstanding AIO requests have been handled.
757	callback has not been invoked yet).
758		1069
759	Example: wait till there are no outstanding requests anymore:	1070	Strictly equivalent to:
760		1071
761	IO::AIO::poll_wait, IO::AIO::poll_cb	1072	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	1073	while IO::AIO::nreqs;
763		1074
764	=item IO::AIO::flush	1075	=head3 CONTROLLING THE NUMBER OF THREADS
765
766	Wait till all outstanding AIO requests have been handled.
767
768	Strictly equivalent to:
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		1076
782	=item IO::AIO::min_parallel $nthreads	1077	=item IO::AIO::min_parallel $nthreads
783		1078
784	Set the minimum number of AIO threads to C<$nthreads>. The current	1079	Set the minimum number of AIO threads to C<$nthreads>. The current
785	default is C<8>, which means eight asynchronous operations can execute	1080	default is C<8>, which means eight asynchronous operations can execute
786	concurrently at any one time (the number of outstanding requests,	1081	concurrently at any one time (the number of outstanding requests,
787	however, is unlimited).	1082	however, is unlimited).
788		1083
789	IO::AIO starts threads only on demand, when an AIO request is queued and	1084	IO::AIO starts threads only on demand, when an AIO request is queued and
790	no free thread exists.	1085	no free thread exists. Please note that queueing up a hundred requests can
		1086	create demand for a hundred threads, even if it turns out that everything
		1087	is in the cache and could have been processed faster by a single thread.
791		1088
792	It is recommended to keep the number of threads relatively low, as some	1089	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	1090	Linux kernel versions will scale negatively with the number of threads
794	(higher parallelity => MUCH higher latency). With current Linux 2.6	1091	(higher parallelity => MUCH higher latency). With current Linux 2.6
795	versions, 4-32 threads should be fine.	1092	versions, 4-32 threads should be fine.
…		…
809	This module automatically runs C<max_parallel 0> at program end, to ensure	1106	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.	1107	that all threads are killed and that there are no outstanding requests.
811		1108
812	Under normal circumstances you don't need to call this function.	1109	Under normal circumstances you don't need to call this function.
813		1110
		1111	=item IO::AIO::max_idle $nthreads
		1112
		1113	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1114	threads that did not get a request to process within 10 seconds). That
		1115	means if a thread becomes idle while C<$nthreads> other threads are also
		1116	idle, it will free its resources and exit.
		1117
		1118	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1119	to allow for extremely high load situations, but want to free resources
		1120	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1121
		1122	The default is probably ok in most situations, especially if thread
		1123	creation is fast. If thread creation is very slow on your system you might
		1124	want to use larger values.
		1125
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1126	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		1127
816	[DEPRECATED]	1128	This is a very bad function to use in interactive programs because it
		1129	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1130	use an C<aio_group> together with a feed callback.
817		1131
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1132	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	try to queue up more than this number of requests, the caller will block until	1133	to queue up more than this number of requests, the next call to the
820	some requests have been handled.	1134	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1135	function will block until the limit is no longer exceeded.
821		1136
822	The default is very large, so normally there is no practical limit. If you	1137	The default value is very large, so there is no practical limit on the
823	queue up many requests in a loop it often improves speed if you set	1138	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		1139
826	This function does not work well together with C<aio_group>'s, and their	1140	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	1141	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
828	this function.	1142	as a stop gap to shield against fatal memory overflow (with large values).
829		1143
830	Under normal circumstances you don't need to call this function.	1144	=head3 STATISTICAL INFORMATION
		1145
		1146	=item IO::AIO::nreqs
		1147
		1148	Returns the number of requests currently in the ready, execute or pending
		1149	states (i.e. for which their callback has not been invoked yet).
		1150
		1151	Example: wait till there are no outstanding requests anymore:
		1152
		1153	IO::AIO::poll_wait, IO::AIO::poll_cb
		1154	while IO::AIO::nreqs;
		1155
		1156	=item IO::AIO::nready
		1157
		1158	Returns the number of requests currently in the ready state (not yet
		1159	executed).
		1160
		1161	=item IO::AIO::npending
		1162
		1163	Returns the number of requests currently in the pending state (executed,
		1164	but not yet processed by poll_cb).
831		1165
832	=back	1166	=back
833		1167
834	=cut	1168	=cut
835		1169
…		…
849	*$sym	1183	*$sym
850	}	1184	}
851		1185
852	min_parallel 8;	1186	min_parallel 8;
853		1187
854	END {	1188	END { flush }
855	max_parallel 0;
856	}
857		1189
858	1;	1190	1;
859		1191
860	=head2 FORK BEHAVIOUR	1192	=head2 FORK BEHAVIOUR
861		1193
862	This module should do "the right thing" when the process using it forks:	1194	This module should do "the right thing" when the process using it forks:
863		1195
864	Before the fork, IO::AIO enters a quiescent state where no requests	1196	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	1197	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	1198	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1199	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	1200	(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	1201	parent). Threads will be started on demand until the limit set in the
870	parent process has been reached again.	1202	parent process has been reached again.
871		1203
872	In short: the parent will, after a short pause, continue as if fork had	1204	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	1205	not been called, while the child will act as if IO::AIO has not been used
874	yet.	1206	yet.
875		1207
876	=head2 MEMORY USAGE	1208	=head2 MEMORY USAGE
877		1209
		1210	Per-request usage:
		1211
878	Each aio request uses - depending on your architecture - around 128 bytes	1212	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	1213	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	1214	a few hundred bytes), readdir requires a result buffer and so on. Perl
881	also be locked.	1215	scalars and other data passed into aio requests will also be locked and
		1216	will consume memory till the request has entered the done state.
882		1217
883	This is now awfully much, so queuing lots of requests is not usually a	1218	This is now awfully much, so queuing lots of requests is not usually a
884	problem.	1219	problem.
885		1220
886	Each thread needs a stack area which is usually around 16k, sometimes much	1221	Per-thread usage:
887	larger, depending on the OS.	1222
		1223	In the execution phase, some aio requests require more memory for
		1224	temporary buffers, and each thread requires a stack and other data
		1225	structures (usually around 16k-128k, depending on the OS).
		1226
		1227	=head1 KNOWN BUGS
		1228
		1229	Known bugs will be fixed in the next release.
888		1230
889	=head1 SEE ALSO	1231	=head1 SEE ALSO
890		1232
891	L<Coro>, L<Linux::AIO> (obsolete).	1233	L<Coro::AIO>.
892		1234
893	=head1 AUTHOR	1235	=head1 AUTHOR
894		1236
895	Marc Lehmann <schmorp@schmorp.de>	1237	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1238	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 1.100 by root, Sun Jan 7 21:36:58 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 1.100 by root, Sun Jan 7 21:36:58 2007 UTC