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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.111 by root, Mon Aug 13 12:08:13 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
…		…
51	=head1 DESCRIPTION	52	=head1 DESCRIPTION
52		53
53	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
54	operating system supports.	55	operating system supports.
55		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
		68	example sockets), using these functions on file descriptors that
		69	support nonblocking operation (again, sockets, pipes etc.) is very
		70	inefficient. Use an event loop for that (such as the L<Event\|Event>
		71	module): IO::AIO will naturally fit into such an event loop itself.
		72
56	Currently, a number of threads are started that execute your read/writes	73	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	74	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	75	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	76	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	77	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	79	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	80	aio_write, so the remaining functionality would have to be implemented
		81	using threads anyway.
64		82
65	Although the module will work with in the presence of other threads,	83	Although the module will work in the presence of other (Perl-) threads,
66	it is currently not reentrant in any way, so use appropriate locking	84	it is currently not reentrant in any way, so use appropriate locking
67	yourself, always call C<poll_cb> from within the same thread, or never	85	yourself, always call C<poll_cb> from within the same thread, or never
68	call C<poll_cb> (or other C<aio_> functions) recursively.	86	call C<poll_cb> (or other C<aio_> functions) recursively.
69		87
		88	=head2 EXAMPLE
		89
		90	This is a simple example that uses the Event module and loads
		91	F</etc/passwd> asynchronously:
		92
		93	use Fcntl;
		94	use Event;
		95	use IO::AIO;
		96
		97	# register the IO::AIO callback with Event
		98	Event->io (fd => IO::AIO::poll_fileno,
		99	poll => 'r',
		100	cb => \&IO::AIO::poll_cb);
		101
		102	# queue the request to open /etc/passwd
		103	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		104	my $fh = shift
		105	or die "error while opening: $!";
		106
		107	# stat'ing filehandles is generally non-blocking
		108	my $size = -s $fh;
		109
		110	# queue a request to read the file
		111	my $contents;
		112	aio_read $fh, 0, $size, $contents, 0, sub {
		113	$_[0] == $size
		114	or die "short read: $!";
		115
		116	close $fh;
		117
		118	# file contents now in $contents
		119	print $contents;
		120
		121	# exit event loop and program
		122	Event::unloop;
		123	};
		124	};
		125
		126	# possibly queue up other requests, or open GUI windows,
		127	# check for sockets etc. etc.
		128
		129	# process events as long as there are some:
		130	Event::loop;
		131
		132	=head1 REQUEST ANATOMY AND LIFETIME
		133
		134	Every C<aio_*> function creates a request. which is a C data structure not
		135	directly visible to Perl.
		136
		137	If called in non-void context, every request function returns a Perl
		138	object representing the request. In void context, nothing is returned,
		139	which saves a bit of memory.
		140
		141	The perl object is a fairly standard ref-to-hash object. The hash contents
		142	are not used by IO::AIO so you are free to store anything you like in it.
		143
		144	During their existance, aio requests travel through the following states,
		145	in order:
		146
		147	=over 4
		148
		149	=item ready
		150
		151	Immediately after a request is created it is put into the ready state,
		152	waiting for a thread to execute it.
		153
		154	=item execute
		155
		156	A thread has accepted the request for processing and is currently
		157	executing it (e.g. blocking in read).
		158
		159	=item pending
		160
		161	The request has been executed and is waiting for result processing.
		162
		163	While request submission and execution is fully asynchronous, result
		164	processing is not and relies on the perl interpreter calling C<poll_cb>
		165	(or another function with the same effect).
		166
		167	=item result
		168
		169	The request results are processed synchronously by C<poll_cb>.
		170
		171	The C<poll_cb> function will process all outstanding aio requests by
		172	calling their callbacks, freeing memory associated with them and managing
		173	any groups they are contained in.
		174
		175	=item done
		176
		177	Request has reached the end of its lifetime and holds no resources anymore
		178	(except possibly for the Perl object, but its connection to the actual
		179	aio request is severed and calling its methods will either do nothing or
		180	result in a runtime error).
		181
		182	=back
		183
70	=cut	184	=cut
71		185
72	package IO::AIO;	186	package IO::AIO;
73		187
74	no warnings;	188	no warnings;
75	use strict 'vars';	189	use strict 'vars';
76		190
77	use base 'Exporter';	191	use base 'Exporter';
78		192
79	BEGIN {	193	BEGIN {
80	our $VERSION = '2.0';	194	our $VERSION = '2.4';
81		195
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	196	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	197	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	198	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
85	aio_group aio_nop);	199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
		200	aio_chown aio_chmod aio_utime aio_truncate);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	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);
89		206
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		208
92	require XSLoader;	209	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
94	}	211	}
95		212
96	=head1 FUNCTIONS	213	=head1 FUNCTIONS
97		214
98	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
99		216
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
103	which must be a code reference. This code reference will get called with	220	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
107		224
108	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	226	internally until the request has finished.
110		227
111	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
112	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
113		230
114	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
115	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
116	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
118	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
119		237
120	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
121	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
123	your pathnames to the locale (or other) encoding in effect in the user	241	your pathnames to the locale (or other) encoding in effect in the user
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	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.
126		247
127	=over 4	248	=over 4
128		249
129	=item aioreq_pri $pri	250	=item $prev_pri = aioreq_pri [$pri]
130		251
131	Sets the priority for the next aio request. The default priority	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
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
134		258
135	The priority will be reset to C<0> after each call to one of the C<aio_>	259	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	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
		277	=item aioreq_nice $pri_adjust
		278
		279	Similar to C<aioreq_pri>, but subtracts the given value from the current
		280	priority, so the effect is cumulative.
		281
137		282
138	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
139		284
140	Asynchronously open or create a file and call the callback with a newly	285	Asynchronously open or create a file and call the callback with a newly
141	created filehandle for the file.	286	created filehandle for the file.
…		…
147	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
148		293
149	Likewise, C<$mode> specifies the mode of the newly created file, if it	294	Likewise, C<$mode> specifies the mode of the newly created file, if it
150	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	295	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
151	except that it is mandatory (i.e. use C<0> if you don't create new files,	296	except that it is mandatory (i.e. use C<0> if you don't create new files,
152	and C<0666> or C<0777> if you do).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
153		300
154	Example:	301	Example:
155		302
156	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
157	if ($_[0]) {	304	if ($_[0]) {
…		…
160	} else {	307	} else {
161	die "open failed: $!\n";	308	die "open failed: $!\n";
162	}	309	}
163	};	310	};
164		311
		312
165	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
166		314
167	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
168	code. I<WARNING:> although accepted, you should not pass in a perl	316	code. I<WARNING:> although accepted, you should not pass in a perl
169	filehandle here, as perl will likely close the file descriptor another	317	filehandle here, as perl will likely close the file descriptor another
…		…
171	C<close> or just let filehandles go out of scope.	319	C<close> or just let filehandles go out of scope.
172		320
173	This is supposed to be a bug in the API, so that might change. It's	321	This is supposed to be a bug in the API, so that might change. It's
174	therefore best to avoid this function.	322	therefore best to avoid this function.
175		323
		324
176	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
177		326
178	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	327	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
179		328
180	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	329	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
181	into the scalar given by C<data> and offset C<dataoffset> and calls the	330	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
182	callback without the actual number of bytes read (or -1 on error, just	331	callback without the actual number of bytes read (or -1 on error, just
183	like the syscall).	332	like the syscall).
184		333
		334	If C<$offset> is undefined, then the current file offset will be used (and
		335	updated), otherwise the file offset will not be changed by these calls.
		336
		337	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		338
		339	If C<$dataoffset> is less than zero, it will be counted from the end of
		340	C<$data>.
		341
185	The C<$data> scalar I<MUST NOT> be modified in any way while the request	342	The C<$data> scalar I<MUST NOT> be modified in any way while the request
186	is outstanding. Modifying it can result in segfaults or WW3 (if the	343	is outstanding. Modifying it can result in segfaults or World War III (if
187	necessary/optional hardware is installed).	344	the necessary/optional hardware is installed).
188		345
189	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	346	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
190	offset C<0> within the scalar:	347	offset C<0> within the scalar:
191		348
192	aio_read $fh, 7, 15, $buffer, 0, sub {	349	aio_read $fh, 7, 15, $buffer, 0, sub {
193	$_[0] > 0 or die "read error: $!";	350	$_[0] > 0 or die "read error: $!";
194	print "read $_[0] bytes: <$buffer>\n";	351	print "read $_[0] bytes: <$buffer>\n";
195	};	352	};
196		353
197	=item aio_move $srcpath, $dstpath, $callback->($status)
198
199	[EXPERIMENTAL due to internal aio_group use]
200
201	Try to move the I<file> (directories not supported as either source or
202	destination) from C<$srcpath> to C<$dstpath> and call the callback with
203	the C<0> (error) or C<-1> ok.
204
205	This is a composite request that tries to rename(2) the file first. If
206	rename files with C<EXDEV>, it creates the destination file with mode 0200
207	and copies the contents of the source file into it using C<aio_sendfile>,
208	followed by restoring atime, mtime, access mode and uid/gid, in that
209	order, and unlinking the C<$srcpath>.
210
211	If an error occurs, the partial destination file will be unlinked, if
212	possible, except when setting atime, mtime, access mode and uid/gid, where
213	errors are being ignored.
214
215	=cut
216
217	sub aio_move($$$) {
218	my ($src, $dst, $cb) = @_;
219
220	my $grp = aio_group $cb;
221
222	add $grp aio_rename $src, $dst, sub {
223	if ($_[0] && $! == EXDEV) {
224	add $grp aio_open $src, O_RDONLY, 0, sub {
225	if (my $src_fh = $_[0]) {
226	my @stat = stat $src_fh;
227
228	add $grp aio_open $dst, O_WRONLY, 0200, sub {
229	if (my $dst_fh = $_[0]) {
230	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
231	close $src_fh;
232
233	if ($_[0] == $stat[7]) {
234	utime $stat[8], $stat[9], $dst;
235	chmod $stat[2] & 07777, $dst_fh;
236	chown $stat[4], $stat[5], $dst_fh;
237	close $dst_fh;
238
239	add $grp aio_unlink $src, sub {
240	$grp->result ($_[0]);
241	};
242	} else {
243	my $errno = $!;
244	add $grp aio_unlink $dst, sub {
245	$! = $errno;
246	$grp->result (-1);
247	};
248	}
249	};
250	} else {
251	$grp->result (-1);
252	}
253	},
254
255	} else {
256	$grp->result (-1);
257	}
258	};
259	} else {
260	$grp->result ($_[0]);
261	}
262	};
263
264	$grp
265	}
266		354
267	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	355	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
268		356
269	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	357	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
270	reading at byte offset C<$in_offset>, and starts writing at the current	358	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
284	C<$in_fh> than are written, and there is no way to find out how many	372	C<$in_fh> than are written, and there is no way to find out how many
285	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	373	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
286	provides the number of bytes written to C<$out_fh>. Only if the result	374	provides the number of bytes written to C<$out_fh>. Only if the result
287	value equals C<$length> one can assume that C<$length> bytes have been	375	value equals C<$length> one can assume that C<$length> bytes have been
288	read.	376	read.
		377
289		378
290	=item aio_readahead $fh,$offset,$length, $callback->($retval)	379	=item aio_readahead $fh,$offset,$length, $callback->($retval)
291		380
292	C<aio_readahead> populates the page cache with data from a file so that	381	C<aio_readahead> populates the page cache with data from a file so that
293	subsequent reads from that file will not block on disk I/O. The C<$offset>	382	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
299	file. The current file offset of the file is left unchanged.	388	file. The current file offset of the file is left unchanged.
300		389
301	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	390	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
302	emulated by simply reading the data, which would have a similar effect.	391	emulated by simply reading the data, which would have a similar effect.
303		392
		393
304	=item aio_stat $fh_or_path, $callback->($status)	394	=item aio_stat $fh_or_path, $callback->($status)
305		395
306	=item aio_lstat $fh, $callback->($status)	396	=item aio_lstat $fh, $callback->($status)
307		397
308	Works like perl's C<stat> or C<lstat> in void context. The callback will	398	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
321	aio_stat "/etc/passwd", sub {	411	aio_stat "/etc/passwd", sub {
322	$_[0] and die "stat failed: $!";	412	$_[0] and die "stat failed: $!";
323	print "size is ", -s _, "\n";	413	print "size is ", -s _, "\n";
324	};	414	};
325		415
		416
		417	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		418
		419	Works like perl's C<utime> function (including the special case of $atime
		420	and $mtime being undef). Fractional times are supported if the underlying
		421	syscalls support them.
		422
		423	When called with a pathname, uses utimes(2) if available, otherwise
		424	utime(2). If called on a file descriptor, uses futimes(2) if available,
		425	otherwise returns ENOSYS, so this is not portable.
		426
		427	Examples:
		428
		429	# set atime and mtime to current time (basically touch(1)):
		430	aio_utime "path", undef, undef;
		431	# set atime to current time and mtime to beginning of the epoch:
		432	aio_utime "path", time, undef; # undef==0
		433
		434
		435	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		436
		437	Works like perl's C<chown> function, except that C<undef> for either $uid
		438	or $gid is being interpreted as "do not change" (but -1 can also be used).
		439
		440	Examples:
		441
		442	# same as "chown root path" in the shell:
		443	aio_chown "path", 0, -1;
		444	# same as above:
		445	aio_chown "path", 0, undef;
		446
		447
		448	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		449
		450	Works like truncate(2) or ftruncate(2).
		451
		452
		453	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		454
		455	Works like perl's C<chmod> function.
		456
		457
326	=item aio_unlink $pathname, $callback->($status)	458	=item aio_unlink $pathname, $callback->($status)
327		459
328	Asynchronously unlink (delete) a file and call the callback with the	460	Asynchronously unlink (delete) a file and call the callback with the
329	result code.	461	result code.
330		462
		463
		464	=item aio_mknod $path, $mode, $dev, $callback->($status)
		465
		466	[EXPERIMENTAL]
		467
		468	Asynchronously create a device node (or fifo). See mknod(2).
		469
		470	The only (POSIX-) portable way of calling this function is:
		471
		472	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		473
		474
331	=item aio_link $srcpath, $dstpath, $callback->($status)	475	=item aio_link $srcpath, $dstpath, $callback->($status)
332		476
333	Asynchronously create a new link to the existing object at C<$srcpath> at	477	Asynchronously create a new link to the existing object at C<$srcpath> at
334	the path C<$dstpath> and call the callback with the result code.	478	the path C<$dstpath> and call the callback with the result code.
335		479
		480
336	=item aio_symlink $srcpath, $dstpath, $callback->($status)	481	=item aio_symlink $srcpath, $dstpath, $callback->($status)
337		482
338	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	483	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
339	the path C<$dstpath> and call the callback with the result code.	484	the path C<$dstpath> and call the callback with the result code.
340		485
		486
		487	=item aio_readlink $path, $callback->($link)
		488
		489	Asynchronously read the symlink specified by C<$path> and pass it to
		490	the callback. If an error occurs, nothing or undef gets passed to the
		491	callback.
		492
		493
341	=item aio_rename $srcpath, $dstpath, $callback->($status)	494	=item aio_rename $srcpath, $dstpath, $callback->($status)
342		495
343	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	496	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
344	rename(2) and call the callback with the result code.	497	rename(2) and call the callback with the result code.
345		498
		499
		500	=item aio_mkdir $pathname, $mode, $callback->($status)
		501
		502	Asynchronously mkdir (create) a directory and call the callback with
		503	the result code. C<$mode> will be modified by the umask at the time the
		504	request is executed, so do not change your umask.
		505
		506
346	=item aio_rmdir $pathname, $callback->($status)	507	=item aio_rmdir $pathname, $callback->($status)
347		508
348	Asynchronously rmdir (delete) a directory and call the callback with the	509	Asynchronously rmdir (delete) a directory and call the callback with the
349	result code.	510	result code.
		511
350		512
351	=item aio_readdir $pathname, $callback->($entries)	513	=item aio_readdir $pathname, $callback->($entries)
352		514
353	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	515	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
354	directory (i.e. opendir + readdir + closedir). The entries will not be	516	directory (i.e. opendir + readdir + closedir). The entries will not be
355	sorted, and will B<NOT> include the C<.> and C<..> entries.	517	sorted, and will B<NOT> include the C<.> and C<..> entries.
356		518
357	The callback a single argument which is either C<undef> or an array-ref	519	The callback a single argument which is either C<undef> or an array-ref
358	with the filenames.	520	with the filenames.
359		521
		522
		523	=item aio_load $path, $data, $callback->($status)
		524
		525	This is a composite request that tries to fully load the given file into
		526	memory. Status is the same as with aio_read.
		527
		528	=cut
		529
		530	sub aio_load($$;$) {
		531	aio_block {
		532	my ($path, undef, $cb) = @_;
		533	my $data = \$_[1];
		534
		535	my $pri = aioreq_pri;
		536	my $grp = aio_group $cb;
		537
		538	aioreq_pri $pri;
		539	add $grp aio_open $path, O_RDONLY, 0, sub {
		540	my $fh = shift
		541	or return $grp->result (-1);
		542
		543	aioreq_pri $pri;
		544	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		545	$grp->result ($_[0]);
		546	};
		547	};
		548
		549	$grp
		550	}
		551	}
		552
		553	=item aio_copy $srcpath, $dstpath, $callback->($status)
		554
		555	Try to copy the I<file> (directories not supported as either source or
		556	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		557	the C<0> (error) or C<-1> ok.
		558
		559	This is a composite request that it creates the destination file with
		560	mode 0200 and copies the contents of the source file into it using
		561	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		562	uid/gid, in that order.
		563
		564	If an error occurs, the partial destination file will be unlinked, if
		565	possible, except when setting atime, mtime, access mode and uid/gid, where
		566	errors are being ignored.
		567
		568	=cut
		569
		570	sub aio_copy($$;$) {
		571	aio_block {
		572	my ($src, $dst, $cb) = @_;
		573
		574	my $pri = aioreq_pri;
		575	my $grp = aio_group $cb;
		576
		577	aioreq_pri $pri;
		578	add $grp aio_open $src, O_RDONLY, 0, sub {
		579	if (my $src_fh = $_[0]) {
		580	my @stat = stat $src_fh;
		581
		582	aioreq_pri $pri;
		583	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		584	if (my $dst_fh = $_[0]) {
		585	aioreq_pri $pri;
		586	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		587	if ($_[0] == $stat[7]) {
		588	$grp->result (0);
		589	close $src_fh;
		590
		591	# those should not normally block. should. should.
		592	utime $stat[8], $stat[9], $dst;
		593	chmod $stat[2] & 07777, $dst_fh;
		594	chown $stat[4], $stat[5], $dst_fh;
		595	close $dst_fh;
		596	} else {
		597	$grp->result (-1);
		598	close $src_fh;
		599	close $dst_fh;
		600
		601	aioreq $pri;
		602	add $grp aio_unlink $dst;
		603	}
		604	};
		605	} else {
		606	$grp->result (-1);
		607	}
		608	},
		609
		610	} else {
		611	$grp->result (-1);
		612	}
		613	};
		614
		615	$grp
		616	}
		617	}
		618
		619	=item aio_move $srcpath, $dstpath, $callback->($status)
		620
		621	Try to move the I<file> (directories not supported as either source or
		622	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		623	the C<0> (error) or C<-1> ok.
		624
		625	This is a composite request that tries to rename(2) the file first. If
		626	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		627	that is successful, unlinking the C<$srcpath>.
		628
		629	=cut
		630
		631	sub aio_move($$;$) {
		632	aio_block {
		633	my ($src, $dst, $cb) = @_;
		634
		635	my $pri = aioreq_pri;
		636	my $grp = aio_group $cb;
		637
		638	aioreq_pri $pri;
		639	add $grp aio_rename $src, $dst, sub {
		640	if ($_[0] && $! == EXDEV) {
		641	aioreq_pri $pri;
		642	add $grp aio_copy $src, $dst, sub {
		643	$grp->result ($_[0]);
		644
		645	if (!$_[0]) {
		646	aioreq_pri $pri;
		647	add $grp aio_unlink $src;
		648	}
		649	};
		650	} else {
		651	$grp->result ($_[0]);
		652	}
		653	};
		654
		655	$grp
		656	}
		657	}
		658
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	659	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		660
362	[EXPERIMENTAL due to internal aio_group use]
363
364	Scans a directory (similar to C<aio_readdir>) but additionally tries to	661	Scans a directory (similar to C<aio_readdir>) but additionally tries to
365	separate the entries of directory C<$path> into two sets of names, ones	662	efficiently separate the entries of directory C<$path> into two sets of
366	you can recurse into (directories or links to them), and ones you cannot	663	names, directories you can recurse into (directories), and ones you cannot
367	recurse into (everything else).	664	recurse into (everything else, including symlinks to directories).
368		665
369	C<aio_scandir> is a composite request that creates of many sub requests_	666	C<aio_scandir> is a composite request that creates of many sub requests_
370	C<$maxreq> specifies the maximum number of outstanding aio requests that	667	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	this function generates. If it is C<< <= 0 >>, then a suitable default	668	this function generates. If it is C<< <= 0 >>, then a suitable default
372	will be chosen (currently 6).	669	will be chosen (currently 4).
373		670
374	On error, the callback is called without arguments, otherwise it receives	671	On error, the callback is called without arguments, otherwise it receives
375	two array-refs with path-relative entry names.	672	two array-refs with path-relative entry names.
376		673
377	Example:	674	Example:
…		…
411	as those tend to return 0 or 1 as link counts, which disables the	708	as those tend to return 0 or 1 as link counts, which disables the
412	directory counting heuristic.	709	directory counting heuristic.
413		710
414	=cut	711	=cut
415		712
416	sub aio_scandir($$$) {	713	sub aio_scandir($$;$) {
		714	aio_block {
417	my ($path, $maxreq, $cb) = @_;	715	my ($path, $maxreq, $cb) = @_;
418		716
		717	my $pri = aioreq_pri;
		718
419	my $grp = aio_group $cb;	719	my $grp = aio_group $cb;
420		720
421	$maxreq = 6 if $maxreq <= 0;	721	$maxreq = 4 if $maxreq <= 0;
422		722
423	# stat once	723	# stat once
		724	aioreq_pri $pri;
424	add $grp aio_stat $path, sub {	725	add $grp aio_stat $path, sub {
425	return $grp->result () if $_[0];	726	return $grp->result () if $_[0];
426	my $now = time;	727	my $now = time;
427	my $hash1 = join ":", (stat _)[0,1,3,7,9];	728	my $hash1 = join ":", (stat _)[0,1,3,7,9];
428		729
429	# read the directory entries	730	# read the directory entries
		731	aioreq_pri $pri;
430	add $grp aio_readdir $path, sub {	732	add $grp aio_readdir $path, sub {
431	my $entries = shift	733	my $entries = shift
432	or return $grp->result ();	734	or return $grp->result ();
433		735
434	# stat the dir another time	736	# stat the dir another time
		737	aioreq_pri $pri;
435	add $grp aio_stat $path, sub {	738	add $grp aio_stat $path, sub {
436	my $hash2 = join ":", (stat _)[0,1,3,7,9];	739	my $hash2 = join ":", (stat _)[0,1,3,7,9];
437		740
438	my $ndirs;	741	my $ndirs;
439		742
440	# take the slow route if anything looks fishy	743	# take the slow route if anything looks fishy
441	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	744	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
442	$ndirs = -1;	745	$ndirs = -1;
443	} else {	746	} else {
444	# if nlink == 2, we are finished	747	# if nlink == 2, we are finished
445	# on non-posix-fs's, we rely on nlink < 2	748	# on non-posix-fs's, we rely on nlink < 2
446	$ndirs = (stat _)[3] - 2	749	$ndirs = (stat _)[3] - 2
447	or return $grp->result ([], $entries);	750	or return $grp->result ([], $entries);
448	}	751	}
449		752
450	# sort into likely dirs and likely nondirs	753	# sort into likely dirs and likely nondirs
451	# dirs == files without ".", short entries first	754	# dirs == files without ".", short entries first
452	$entries = [map $_->[0],	755	$entries = [map $_->[0],
453	sort { $b->[1] cmp $a->[1] }	756	sort { $b->[1] cmp $a->[1] }
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	757	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	758	@$entries];
456		759
457	my (@dirs, @nondirs);	760	my (@dirs, @nondirs);
458		761
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	762	my $statgrp = add $grp aio_group sub {
463
464	$schedcb = sub {
465	if (@$entries) {
466	if ($nreq < $maxreq) {
467	my $ent = pop @$entries;
468	$nreq++;
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);	763	$grp->result (\@dirs, \@nondirs);
477	}	764	};
		765
		766	limit $statgrp $maxreq;
		767	feed $statgrp sub {
		768	return unless @$entries;
		769	my $entry = pop @$entries;
		770
		771	aioreq_pri $pri;
		772	add $statgrp aio_stat "$path/$entry/.", sub {
		773	if ($_[0] < 0) {
		774	push @nondirs, $entry;
		775	} else {
		776	# need to check for real directory
		777	aioreq_pri $pri;
		778	add $statgrp aio_lstat "$path/$entry", sub {
		779	if (-d _) {
		780	push @dirs, $entry;
		781
		782	unless (--$ndirs) {
		783	push @nondirs, @$entries;
		784	feed $statgrp;
		785	}
		786	} else {
		787	push @nondirs, $entry;
		788	}
		789	}
		790	}
		791	};
		792	};
478	};	793	};
479	$statcb = sub {
480	my ($status, $entry) = @_;
481
482	if ($status < 0) {
483	$nreq--;
484	push @nondirs, $entry;
485	&$schedcb;
486	} else {
487	# need to check for real directory
488	add $grp aio_lstat "$path/$entry", sub {
489	$nreq--;
490
491	if (-d _) {
492	push @dirs, $entry;
493
494	if (!--$ndirs) {
495	push @nondirs, @$entries;
496	$entries = [];
497	}
498	} else {
499	push @nondirs, $entry;
500	}
501
502	&$schedcb;
503	}
504	}
505	};
506
507	&$schedcb while @$entries && $nreq < $maxreq;
508	};	794	};
509	};	795	};
		796
		797	$grp
510	};	798	}
		799	}
511		800
		801	=item aio_rmtree $path, $callback->($status)
		802
		803	Delete a directory tree starting (and including) C<$path>, return the
		804	status of the final C<rmdir> only. This is a composite request that
		805	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		806	everything else.
		807
		808	=cut
		809
		810	sub aio_rmtree;
		811	sub aio_rmtree($;$) {
		812	aio_block {
		813	my ($path, $cb) = @_;
		814
		815	my $pri = aioreq_pri;
		816	my $grp = aio_group $cb;
		817
		818	aioreq_pri $pri;
		819	add $grp aio_scandir $path, 0, sub {
		820	my ($dirs, $nondirs) = @_;
		821
		822	my $dirgrp = aio_group sub {
		823	add $grp aio_rmdir $path, sub {
		824	$grp->result ($_[0]);
		825	};
		826	};
		827
		828	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		829	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		830
		831	add $grp $dirgrp;
		832	};
		833
512	$grp	834	$grp
		835	}
513	}	836	}
514		837
515	=item aio_fsync $fh, $callback->($status)	838	=item aio_fsync $fh, $callback->($status)
516		839
517	Asynchronously call fsync on the given filehandle and call the callback	840	Asynchronously call fsync on the given filehandle and call the callback
…		…
525	If this call isn't available because your OS lacks it or it couldn't be	848	If this call isn't available because your OS lacks it or it couldn't be
526	detected, it will be emulated by calling C<fsync> instead.	849	detected, it will be emulated by calling C<fsync> instead.
527		850
528	=item aio_group $callback->(...)	851	=item aio_group $callback->(...)
529		852
530	[EXPERIMENTAL]
531
532	This is a very special aio request: Instead of doing something, it is a	853	This is a very special aio request: Instead of doing something, it is a
533	container for other aio requests, which is useful if you want to bundle	854	container for other aio requests, which is useful if you want to bundle
534	many requests into a single, composite, request.	855	many requests into a single, composite, request with a definite callback
		856	and the ability to cancel the whole request with its subrequests.
535		857
536	Returns an object of class L<IO::AIO::GRP>. See its documentation below	858	Returns an object of class L<IO::AIO::GRP>. See its documentation below
537	for more info.	859	for more info.
538		860
539	Example:	861	Example:
…		…
558	phase and still requires a worker thread. Thus, the callback will not	880	phase and still requires a worker thread. Thus, the callback will not
559	be executed immediately but only after other requests in the queue have	881	be executed immediately but only after other requests in the queue have
560	entered their execution phase. This can be used to measure request	882	entered their execution phase. This can be used to measure request
561	latency.	883	latency.
562		884
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	885	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		886
565	Mainly used for debugging and benchmarking, this aio request puts one of	887	Mainly used for debugging and benchmarking, this aio request puts one of
566	the request workers to sleep for the given time.	888	the request workers to sleep for the given time.
567		889
568	While it is theoretically handy to have simple I/O scheduling requests	890	While it is theoretically handy to have simple I/O scheduling requests
569	like sleep and file handle readable/writable, the overhead this creates	891	like sleep and file handle readable/writable, the overhead this creates is
570	is immense, so do not use this function except to put your application	892	immense (it blocks a thread for a long time) so do not use this function
571	under artificial I/O pressure.	893	except to put your application under artificial I/O pressure.
572		894
573	=back	895	=back
574		896
575	=head2 IO::AIO::REQ CLASS	897	=head2 IO::AIO::REQ CLASS
576		898
577	All non-aggregate C<aio_*> functions return an object of this class when	899	All non-aggregate C<aio_*> functions return an object of this class when
578	called in non-void context.	900	called in non-void context.
579
580	A request always moves through the following five states in its lifetime,
581	in order: B<ready> (request has been created, but has not been executed
582	yet), B<execute> (request is currently being executed), B<pending>
583	(request has been executed but callback has not been called yet),
584	B<result> (results are being processed synchronously, includes calling the
585	callback) and B<done> (request has reached the end of its lifetime and
586	holds no resources anymore).
587		901
588	=over 4	902	=over 4
589		903
590	=item cancel $req	904	=item cancel $req
591		905
…		…
645	=item * They can also can also be added to other IO::AIO::GRP objects.	959	=item * They can also can also be added to other IO::AIO::GRP objects.
646		960
647	=item * You must not add requests to a group from within the group callback (or	961	=item * You must not add requests to a group from within the group callback (or
648	any later time).	962	any later time).
649		963
650	=item * This does not harmonise well with C<max_outstanding>, so best do
651	not combine C<aio_group> with it. Groups and feeders are recommended for
652	this kind of concurrency-limiting.
653
654	=back	964	=back
655		965
656	Their lifetime, simplified, looks like this: when they are empty, they	966	Their lifetime, simplified, looks like this: when they are empty, they
657	will finish very quickly. If they contain only requests that are in the	967	will finish very quickly. If they contain only requests that are in the
658	C<done> state, they will also finish. Otherwise they will continue to	968	C<done> state, they will also finish. Otherwise they will continue to
…		…
673	be added, including other groups, as long as you do not create circular	983	be added, including other groups, as long as you do not create circular
674	dependencies.	984	dependencies.
675		985
676	Returns all its arguments.	986	Returns all its arguments.
677		987
		988	=item $grp->cancel_subs
		989
		990	Cancel all subrequests and clears any feeder, but not the group request
		991	itself. Useful when you queued a lot of events but got a result early.
		992
678	=item $grp->result (...)	993	=item $grp->result (...)
679		994
680	Set the result value(s) that will be passed to the group callback when all	995	Set the result value(s) that will be passed to the group callback when all
681	subrequests have finished. By default, no argument will be passed.	996	subrequests have finished and set thre groups errno to the current value
		997	of errno (just like calling C<errno> without an error number). By default,
		998	no argument will be passed and errno is zero.
		999
		1000	=item $grp->errno ([$errno])
		1001
		1002	Sets the group errno value to C<$errno>, or the current value of errno
		1003	when the argument is missing.
		1004
		1005	Every aio request has an associated errno value that is restored when
		1006	the callback is invoked. This method lets you change this value from its
		1007	default (0).
		1008
		1009	Calling C<result> will also set errno, so make sure you either set C<$!>
		1010	before the call to C<result>, or call c<errno> after it.
682		1011
683	=item feed $grp $callback->($grp)	1012	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		1013
687	Sets a feeder/generator on this group: every group can have an attached	1014	Sets a feeder/generator on this group: every group can have an attached
688	generator that generates requests if idle. The idea behind this is that,	1015	generator that generates requests if idle. The idea behind this is that,
689	although you could just queue as many requests as you want in a group,	1016	although you could just queue as many requests as you want in a group,
690	this might starve other requests for a potentially long time. For	1017	this might starve other requests for a potentially long time. For
…		…
727		1054
728	=back	1055	=back
729		1056
730	=head2 SUPPORT FUNCTIONS	1057	=head2 SUPPORT FUNCTIONS
731		1058
		1059	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1060
732	=over 4	1061	=over 4
733		1062
734	=item $fileno = IO::AIO::poll_fileno	1063	=item $fileno = IO::AIO::poll_fileno
735		1064
736	Return the I<request result pipe file descriptor>. This filehandle must be	1065	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
740		1069
741	See C<poll_cb> for an example.	1070	See C<poll_cb> for an example.
742		1071
743	=item IO::AIO::poll_cb	1072	=item IO::AIO::poll_cb
744		1073
745	Process all outstanding events on the result pipe. You have to call this	1074	Process some outstanding events on the result pipe. You have to call this
746	regularly. Returns the number of events processed. Returns immediately	1075	regularly. Returns the number of events processed. Returns immediately
747	when no events are outstanding.	1076	when no events are outstanding. The amount of events processed depends on
		1077	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1078
		1079	If not all requests were processed for whatever reason, the filehandle
		1080	will still be ready when C<poll_cb> returns.
748		1081
749	Example: Install an Event watcher that automatically calls	1082	Example: Install an Event watcher that automatically calls
750	IO::AIO::poll_cb with high priority:	1083	IO::AIO::poll_cb with high priority:
751		1084
752	Event->io (fd => IO::AIO::poll_fileno,	1085	Event->io (fd => IO::AIO::poll_fileno,
753	poll => 'r', async => 1,	1086	poll => 'r', async => 1,
754	cb => \&IO::AIO::poll_cb);	1087	cb => \&IO::AIO::poll_cb);
755		1088
		1089	=item IO::AIO::max_poll_reqs $nreqs
		1090
		1091	=item IO::AIO::max_poll_time $seconds
		1092
		1093	These set the maximum number of requests (default C<0>, meaning infinity)
		1094	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1095	the maximum amount of time (default C<0>, meaning infinity) spent in
		1096	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1097	of time C<poll_cb> is allowed to use).
		1098
		1099	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1100	syscall per request processed, which is not normally a problem unless your
		1101	callbacks are really really fast or your OS is really really slow (I am
		1102	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1103
		1104	Setting these is useful if you want to ensure some level of
		1105	interactiveness when perl is not fast enough to process all requests in
		1106	time.
		1107
		1108	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1109
		1110	Example: Install an Event watcher that automatically calls
		1111	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1112	program get the CPU sometimes even under high AIO load.
		1113
		1114	# try not to spend much more than 0.1s in poll_cb
		1115	IO::AIO::max_poll_time 0.1;
		1116
		1117	# use a low priority so other tasks have priority
		1118	Event->io (fd => IO::AIO::poll_fileno,
		1119	poll => 'r', nice => 1,
		1120	cb => &IO::AIO::poll_cb);
		1121
756	=item IO::AIO::poll_wait	1122	=item IO::AIO::poll_wait
757		1123
		1124	If there are any outstanding requests and none of them in the result
758	Wait till the result filehandle becomes ready for reading (simply does a	1125	phase, wait till the result filehandle becomes ready for reading (simply
759	C<select> on the filehandle. This is useful if you want to synchronously wait	1126	does a C<select> on the filehandle. This is useful if you want to
760	for some requests to finish).	1127	synchronously wait for some requests to finish).
761		1128
762	See C<nreqs> for an example.	1129	See C<nreqs> for an example.
763		1130
		1131	=item IO::AIO::poll
		1132
		1133	Waits until some requests have been handled.
		1134
		1135	Returns the number of requests processed, but is otherwise strictly
		1136	equivalent to:
		1137
		1138	IO::AIO::poll_wait, IO::AIO::poll_cb
		1139
764	=item IO::AIO::nreqs	1140	=item IO::AIO::flush
765		1141
766	Returns the number of requests currently outstanding (i.e. for which their	1142	Wait till all outstanding AIO requests have been handled.
767	callback has not been invoked yet).
768		1143
769	Example: wait till there are no outstanding requests anymore:	1144	Strictly equivalent to:
770		1145
771	IO::AIO::poll_wait, IO::AIO::poll_cb	1146	IO::AIO::poll_wait, IO::AIO::poll_cb
772	while IO::AIO::nreqs;	1147	while IO::AIO::nreqs;
773		1148
774	=item IO::AIO::flush	1149	=back
775		1150
776	Wait till all outstanding AIO requests have been handled.	1151	=head3 CONTROLLING THE NUMBER OF THREADS
777		1152
778	Strictly equivalent to:	1153	=over
779
780	IO::AIO::poll_wait, IO::AIO::poll_cb
781	while IO::AIO::nreqs;
782
783	=item IO::AIO::poll
784
785	Waits until some requests have been handled.
786
787	Strictly equivalent to:
788
789	IO::AIO::poll_wait, IO::AIO::poll_cb
790	if IO::AIO::nreqs;
791		1154
792	=item IO::AIO::min_parallel $nthreads	1155	=item IO::AIO::min_parallel $nthreads
793		1156
794	Set the minimum number of AIO threads to C<$nthreads>. The current	1157	Set the minimum number of AIO threads to C<$nthreads>. The current
795	default is C<8>, which means eight asynchronous operations can execute	1158	default is C<8>, which means eight asynchronous operations can execute
796	concurrently at any one time (the number of outstanding requests,	1159	concurrently at any one time (the number of outstanding requests,
797	however, is unlimited).	1160	however, is unlimited).
798		1161
799	IO::AIO starts threads only on demand, when an AIO request is queued and	1162	IO::AIO starts threads only on demand, when an AIO request is queued and
800	no free thread exists.	1163	no free thread exists. Please note that queueing up a hundred requests can
		1164	create demand for a hundred threads, even if it turns out that everything
		1165	is in the cache and could have been processed faster by a single thread.
801		1166
802	It is recommended to keep the number of threads relatively low, as some	1167	It is recommended to keep the number of threads relatively low, as some
803	Linux kernel versions will scale negatively with the number of threads	1168	Linux kernel versions will scale negatively with the number of threads
804	(higher parallelity => MUCH higher latency). With current Linux 2.6	1169	(higher parallelity => MUCH higher latency). With current Linux 2.6
805	versions, 4-32 threads should be fine.	1170	versions, 4-32 threads should be fine.
…		…
819	This module automatically runs C<max_parallel 0> at program end, to ensure	1184	This module automatically runs C<max_parallel 0> at program end, to ensure
820	that all threads are killed and that there are no outstanding requests.	1185	that all threads are killed and that there are no outstanding requests.
821		1186
822	Under normal circumstances you don't need to call this function.	1187	Under normal circumstances you don't need to call this function.
823		1188
		1189	=item IO::AIO::max_idle $nthreads
		1190
		1191	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1192	threads that did not get a request to process within 10 seconds). That
		1193	means if a thread becomes idle while C<$nthreads> other threads are also
		1194	idle, it will free its resources and exit.
		1195
		1196	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1197	to allow for extremely high load situations, but want to free resources
		1198	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1199
		1200	The default is probably ok in most situations, especially if thread
		1201	creation is fast. If thread creation is very slow on your system you might
		1202	want to use larger values.
		1203
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1204	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
825		1205
826	[DEPRECATED]	1206	This is a very bad function to use in interactive programs because it
		1207	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1208	use an C<aio_group> together with a feed callback.
827		1209
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1210	Sets the maximum number of outstanding requests to C<$nreqs>. If you
829	try to queue up more than this number of requests, the caller will block until	1211	to queue up more than this number of requests, the next call to the
830	some requests have been handled.	1212	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1213	function will block until the limit is no longer exceeded.
831		1214
832	The default is very large, so normally there is no practical limit. If you	1215	The default value is very large, so there is no practical limit on the
833	queue up many requests in a loop it often improves speed if you set	1216	number of outstanding requests.
834	this to a relatively low number, such as C<100>.
835		1217
836	This function does not work well together with C<aio_group>'s, and their	1218	You can still queue as many requests as you want. Therefore,
837	feeder interface is better suited to limiting concurrency, so do not use	1219	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
838	this function.	1220	as a stop gap to shield against fatal memory overflow (with large values).
839		1221
840	Under normal circumstances you don't need to call this function.	1222	=back
		1223
		1224	=head3 STATISTICAL INFORMATION
		1225
		1226	=over
		1227
		1228	=item IO::AIO::nreqs
		1229
		1230	Returns the number of requests currently in the ready, execute or pending
		1231	states (i.e. for which their callback has not been invoked yet).
		1232
		1233	Example: wait till there are no outstanding requests anymore:
		1234
		1235	IO::AIO::poll_wait, IO::AIO::poll_cb
		1236	while IO::AIO::nreqs;
		1237
		1238	=item IO::AIO::nready
		1239
		1240	Returns the number of requests currently in the ready state (not yet
		1241	executed).
		1242
		1243	=item IO::AIO::npending
		1244
		1245	Returns the number of requests currently in the pending state (executed,
		1246	but not yet processed by poll_cb).
841		1247
842	=back	1248	=back
843		1249
844	=cut	1250	=cut
845		1251
…		…
859	*$sym	1265	*$sym
860	}	1266	}
861		1267
862	min_parallel 8;	1268	min_parallel 8;
863		1269
864	END {	1270	END { flush }
865	max_parallel 0;
866	}
867		1271
868	1;	1272	1;
869		1273
870	=head2 FORK BEHAVIOUR	1274	=head2 FORK BEHAVIOUR
871		1275
872	This module should do "the right thing" when the process using it forks:	1276	This module should do "the right thing" when the process using it forks:
873		1277
874	Before the fork, IO::AIO enters a quiescent state where no requests	1278	Before the fork, IO::AIO enters a quiescent state where no requests
875	can be added in other threads and no results will be processed. After	1279	can be added in other threads and no results will be processed. After
876	the fork the parent simply leaves the quiescent state and continues	1280	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	1281	request/result processing, while the child frees the request/result queue
878	queue (so the requests started before the fork will only be handled in	1282	(so that the requests started before the fork will only be handled in the
879	the parent). Threads will be started on demand until the limit ste in the	1283	parent). Threads will be started on demand until the limit set in the
880	parent process has been reached again.	1284	parent process has been reached again.
881		1285
882	In short: the parent will, after a short pause, continue as if fork had	1286	In short: the parent will, after a short pause, continue as if fork had
883	not been called, while the child will act as if IO::AIO has not been used	1287	not been called, while the child will act as if IO::AIO has not been used
884	yet.	1288	yet.
885		1289
886	=head2 MEMORY USAGE	1290	=head2 MEMORY USAGE
887		1291
		1292	Per-request usage:
		1293
888	Each aio request uses - depending on your architecture - around 128 bytes	1294	Each aio request uses - depending on your architecture - around 100-200
889	of memory. In addition, stat requests need a stat buffer (possibly a few	1295	bytes of memory. In addition, stat requests need a stat buffer (possibly
890	hundred bytes). Perl scalars and other data passed into aio requests will	1296	a few hundred bytes), readdir requires a result buffer and so on. Perl
891	also be locked.	1297	scalars and other data passed into aio requests will also be locked and
		1298	will consume memory till the request has entered the done state.
892		1299
893	This is now awfully much, so queuing lots of requests is not usually a	1300	This is not awfully much, so queuing lots of requests is not usually a
894	problem.	1301	problem.
895		1302
896	Each thread needs a stack area which is usually around 16k, sometimes much	1303	Per-thread usage:
897	larger, depending on the OS.	1304
		1305	In the execution phase, some aio requests require more memory for
		1306	temporary buffers, and each thread requires a stack and other data
		1307	structures (usually around 16k-128k, depending on the OS).
		1308
		1309	=head1 KNOWN BUGS
		1310
		1311	Known bugs will be fixed in the next release.
898		1312
899	=head1 SEE ALSO	1313	=head1 SEE ALSO
900		1314
901	L<Coro::AIO>.	1315	L<Coro::AIO>.
902		1316

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs. Revision 1.111 by root, Mon Aug 13 12:08:13 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.111 by root, Mon Aug 13 12:08:13 2007 UTC