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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.116 by root, Wed Oct 3 21:27:51 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 = '2.5';
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 aioreq_nice));	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.
137		261
138	Example: open a file with low priority, then read something from it with	262	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	263	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	264	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	271	aio_read $_[0], ..., sub {
148	...	272	...
149	};	273	};
150	};	274	};
151		275
		276
152	=item aioreq_nice $pri_adjust	277	=item aioreq_nice $pri_adjust
153		278
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	279	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	280	priority, so the effect is cumulative.
		281
156		282
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		284
159	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
160	created filehandle for the file.	286	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
167		293
168	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
169	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>,
170	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,
171	and C<0666> or C<0777> if you do).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
172		300
173	Example:	301	Example:
174		302
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
176	if ($_[0]) {	304	if ($_[0]) {
…		…
179	} else {	307	} else {
180	die "open failed: $!\n";	308	die "open failed: $!\n";
181	}	309	}
182	};	310	};
183		311
		312
184	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
185		314
186	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	316	code.
188	filehandle here, as perl will likely close the file descriptor another
189	time when the filehandle is destroyed. Normally, you can safely call perls
190	C<close> or just let filehandles go out of scope.
191		317
192	This is supposed to be a bug in the API, so that might change. It's	318	Unlike the other functions operating on files, this function uses the
193	therefore best to avoid this function.	319	PerlIO layer to close the filehandle. The reason is that the PerlIO API
		320	insists on closing the underlying fd itself, no matter what, and doesn't
		321	allow modifications to the fd. Unfortunately, it is not clear that you can
		322	call PerlIO from different threads (actually, its quite clear that this
		323	won't work in some cases), so while it likely works perfectly with simple
		324	file handles (such as the ones created by C<aio_open>) it might fail in
		325	interesting ways for others.
		326
		327	Having said that, aio_close tries to clean up the filehandle as much as
		328	possible before handing it to an io thread, and generally does work.
		329
194		330
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	331	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		332
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	333	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		334
199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	335	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
200	into the scalar given by C<data> and offset C<dataoffset> and calls the	336	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
201	callback without the actual number of bytes read (or -1 on error, just	337	callback without the actual number of bytes read (or -1 on error, just
202	like the syscall).	338	like the syscall).
203		339
		340	If C<$offset> is undefined, then the current file descriptor offset will
		341	be used (and updated), otherwise the file descriptor offset will not be
		342	changed by these calls.
		343
		344	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		345
		346	If C<$dataoffset> is less than zero, it will be counted from the end of
		347	C<$data>.
		348
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	349	The C<$data> scalar I<MUST NOT> be modified in any way while the request
205	is outstanding. Modifying it can result in segfaults or WW3 (if the	350	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	351	the necessary/optional hardware is installed).
207		352
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	353	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	354	offset C<0> within the scalar:
210		355
211	aio_read $fh, 7, 15, $buffer, 0, sub {	356	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	357	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	358	print "read $_[0] bytes: <$buffer>\n";
214	};	359	};
215		360
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	Try to move the I<file> (directories not supported as either source or
219	destination) from C<$srcpath> to C<$dstpath> and call the callback with
220	the C<0> (error) or C<-1> ok.
221
222	This is a composite request that tries to rename(2) the file first. If
223	rename files with C<EXDEV>, it creates the destination file with mode 0200
224	and copies the contents of the source file into it using C<aio_sendfile>,
225	followed by restoring atime, mtime, access mode and uid/gid, in that
226	order, and unlinking the C<$srcpath>.
227
228	If an error occurs, the partial destination file will be unlinked, if
229	possible, except when setting atime, mtime, access mode and uid/gid, where
230	errors are being ignored.
231
232	=cut
233
234	sub aio_move($$$) {
235	my ($src, $dst, $cb) = @_;
236
237	my $grp = aio_group $cb;
238
239	add $grp aio_rename $src, $dst, sub {
240	if ($_[0] && $! == EXDEV) {
241	add $grp aio_open $src, O_RDONLY, 0, sub {
242	if (my $src_fh = $_[0]) {
243	my @stat = stat $src_fh;
244
245	add $grp aio_open $dst, O_WRONLY, 0200, sub {
246	if (my $dst_fh = $_[0]) {
247	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
248	close $src_fh;
249
250	if ($_[0] == $stat[7]) {
251	utime $stat[8], $stat[9], $dst;
252	chmod $stat[2] & 07777, $dst_fh;
253	chown $stat[4], $stat[5], $dst_fh;
254	close $dst_fh;
255
256	add $grp aio_unlink $src, sub {
257	$grp->result ($_[0]);
258	};
259	} else {
260	my $errno = $!;
261	add $grp aio_unlink $dst, sub {
262	$! = $errno;
263	$grp->result (-1);
264	};
265	}
266	};
267	} else {
268	$grp->result (-1);
269	}
270	},
271
272	} else {
273	$grp->result (-1);
274	}
275	};
276	} else {
277	$grp->result ($_[0]);
278	}
279	};
280
281	$grp
282	}
283		361
284	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	362	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
285		363
286	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	364	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
287	reading at byte offset C<$in_offset>, and starts writing at the current	365	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
301	C<$in_fh> than are written, and there is no way to find out how many	379	C<$in_fh> than are written, and there is no way to find out how many
302	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	380	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
303	provides the number of bytes written to C<$out_fh>. Only if the result	381	provides the number of bytes written to C<$out_fh>. Only if the result
304	value equals C<$length> one can assume that C<$length> bytes have been	382	value equals C<$length> one can assume that C<$length> bytes have been
305	read.	383	read.
		384
306		385
307	=item aio_readahead $fh,$offset,$length, $callback->($retval)	386	=item aio_readahead $fh,$offset,$length, $callback->($retval)
308		387
309	C<aio_readahead> populates the page cache with data from a file so that	388	C<aio_readahead> populates the page cache with data from a file so that
310	subsequent reads from that file will not block on disk I/O. The C<$offset>	389	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
316	file. The current file offset of the file is left unchanged.	395	file. The current file offset of the file is left unchanged.
317		396
318	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	397	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
319	emulated by simply reading the data, which would have a similar effect.	398	emulated by simply reading the data, which would have a similar effect.
320		399
		400
321	=item aio_stat $fh_or_path, $callback->($status)	401	=item aio_stat $fh_or_path, $callback->($status)
322		402
323	=item aio_lstat $fh, $callback->($status)	403	=item aio_lstat $fh, $callback->($status)
324		404
325	Works like perl's C<stat> or C<lstat> in void context. The callback will	405	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
338	aio_stat "/etc/passwd", sub {	418	aio_stat "/etc/passwd", sub {
339	$_[0] and die "stat failed: $!";	419	$_[0] and die "stat failed: $!";
340	print "size is ", -s _, "\n";	420	print "size is ", -s _, "\n";
341	};	421	};
342		422
		423
		424	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		425
		426	Works like perl's C<utime> function (including the special case of $atime
		427	and $mtime being undef). Fractional times are supported if the underlying
		428	syscalls support them.
		429
		430	When called with a pathname, uses utimes(2) if available, otherwise
		431	utime(2). If called on a file descriptor, uses futimes(2) if available,
		432	otherwise returns ENOSYS, so this is not portable.
		433
		434	Examples:
		435
		436	# set atime and mtime to current time (basically touch(1)):
		437	aio_utime "path", undef, undef;
		438	# set atime to current time and mtime to beginning of the epoch:
		439	aio_utime "path", time, undef; # undef==0
		440
		441
		442	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		443
		444	Works like perl's C<chown> function, except that C<undef> for either $uid
		445	or $gid is being interpreted as "do not change" (but -1 can also be used).
		446
		447	Examples:
		448
		449	# same as "chown root path" in the shell:
		450	aio_chown "path", 0, -1;
		451	# same as above:
		452	aio_chown "path", 0, undef;
		453
		454
		455	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		456
		457	Works like truncate(2) or ftruncate(2).
		458
		459
		460	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		461
		462	Works like perl's C<chmod> function.
		463
		464
343	=item aio_unlink $pathname, $callback->($status)	465	=item aio_unlink $pathname, $callback->($status)
344		466
345	Asynchronously unlink (delete) a file and call the callback with the	467	Asynchronously unlink (delete) a file and call the callback with the
346	result code.	468	result code.
347		469
		470
		471	=item aio_mknod $path, $mode, $dev, $callback->($status)
		472
		473	[EXPERIMENTAL]
		474
		475	Asynchronously create a device node (or fifo). See mknod(2).
		476
		477	The only (POSIX-) portable way of calling this function is:
		478
		479	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		480
		481
348	=item aio_link $srcpath, $dstpath, $callback->($status)	482	=item aio_link $srcpath, $dstpath, $callback->($status)
349		483
350	Asynchronously create a new link to the existing object at C<$srcpath> at	484	Asynchronously create a new link to the existing object at C<$srcpath> at
351	the path C<$dstpath> and call the callback with the result code.	485	the path C<$dstpath> and call the callback with the result code.
352		486
		487
353	=item aio_symlink $srcpath, $dstpath, $callback->($status)	488	=item aio_symlink $srcpath, $dstpath, $callback->($status)
354		489
355	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	490	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
356	the path C<$dstpath> and call the callback with the result code.	491	the path C<$dstpath> and call the callback with the result code.
357		492
		493
		494	=item aio_readlink $path, $callback->($link)
		495
		496	Asynchronously read the symlink specified by C<$path> and pass it to
		497	the callback. If an error occurs, nothing or undef gets passed to the
		498	callback.
		499
		500
358	=item aio_rename $srcpath, $dstpath, $callback->($status)	501	=item aio_rename $srcpath, $dstpath, $callback->($status)
359		502
360	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	503	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
361	rename(2) and call the callback with the result code.	504	rename(2) and call the callback with the result code.
362		505
		506
		507	=item aio_mkdir $pathname, $mode, $callback->($status)
		508
		509	Asynchronously mkdir (create) a directory and call the callback with
		510	the result code. C<$mode> will be modified by the umask at the time the
		511	request is executed, so do not change your umask.
		512
		513
363	=item aio_rmdir $pathname, $callback->($status)	514	=item aio_rmdir $pathname, $callback->($status)
364		515
365	Asynchronously rmdir (delete) a directory and call the callback with the	516	Asynchronously rmdir (delete) a directory and call the callback with the
366	result code.	517	result code.
		518
367		519
368	=item aio_readdir $pathname, $callback->($entries)	520	=item aio_readdir $pathname, $callback->($entries)
369		521
370	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	522	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
371	directory (i.e. opendir + readdir + closedir). The entries will not be	523	directory (i.e. opendir + readdir + closedir). The entries will not be
372	sorted, and will B<NOT> include the C<.> and C<..> entries.	524	sorted, and will B<NOT> include the C<.> and C<..> entries.
373		525
374	The callback a single argument which is either C<undef> or an array-ref	526	The callback a single argument which is either C<undef> or an array-ref
375	with the filenames.	527	with the filenames.
376		528
		529
		530	=item aio_load $path, $data, $callback->($status)
		531
		532	This is a composite request that tries to fully load the given file into
		533	memory. Status is the same as with aio_read.
		534
		535	=cut
		536
		537	sub aio_load($$;$) {
		538	aio_block {
		539	my ($path, undef, $cb) = @_;
		540	my $data = \$_[1];
		541
		542	my $pri = aioreq_pri;
		543	my $grp = aio_group $cb;
		544
		545	aioreq_pri $pri;
		546	add $grp aio_open $path, O_RDONLY, 0, sub {
		547	my $fh = shift
		548	or return $grp->result (-1);
		549
		550	aioreq_pri $pri;
		551	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		552	$grp->result ($_[0]);
		553	};
		554	};
		555
		556	$grp
		557	}
		558	}
		559
		560	=item aio_copy $srcpath, $dstpath, $callback->($status)
		561
		562	Try to copy the I<file> (directories not supported as either source or
		563	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		564	the C<0> (error) or C<-1> ok.
		565
		566	This is a composite request that it creates the destination file with
		567	mode 0200 and copies the contents of the source file into it using
		568	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		569	uid/gid, in that order.
		570
		571	If an error occurs, the partial destination file will be unlinked, if
		572	possible, except when setting atime, mtime, access mode and uid/gid, where
		573	errors are being ignored.
		574
		575	=cut
		576
		577	sub aio_copy($$;$) {
		578	aio_block {
		579	my ($src, $dst, $cb) = @_;
		580
		581	my $pri = aioreq_pri;
		582	my $grp = aio_group $cb;
		583
		584	aioreq_pri $pri;
		585	add $grp aio_open $src, O_RDONLY, 0, sub {
		586	if (my $src_fh = $_[0]) {
		587	my @stat = stat $src_fh;
		588
		589	aioreq_pri $pri;
		590	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		591	if (my $dst_fh = $_[0]) {
		592	aioreq_pri $pri;
		593	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		594	if ($_[0] == $stat[7]) {
		595	$grp->result (0);
		596	close $src_fh;
		597
		598	# those should not normally block. should. should.
		599	utime $stat[8], $stat[9], $dst;
		600	chmod $stat[2] & 07777, $dst_fh;
		601	chown $stat[4], $stat[5], $dst_fh;
		602	close $dst_fh;
		603	} else {
		604	$grp->result (-1);
		605	close $src_fh;
		606	close $dst_fh;
		607
		608	aioreq $pri;
		609	add $grp aio_unlink $dst;
		610	}
		611	};
		612	} else {
		613	$grp->result (-1);
		614	}
		615	},
		616
		617	} else {
		618	$grp->result (-1);
		619	}
		620	};
		621
		622	$grp
		623	}
		624	}
		625
		626	=item aio_move $srcpath, $dstpath, $callback->($status)
		627
		628	Try to move the I<file> (directories not supported as either source or
		629	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		630	the C<0> (error) or C<-1> ok.
		631
		632	This is a composite request that tries to rename(2) the file first. If
		633	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		634	that is successful, unlinking the C<$srcpath>.
		635
		636	=cut
		637
		638	sub aio_move($$;$) {
		639	aio_block {
		640	my ($src, $dst, $cb) = @_;
		641
		642	my $pri = aioreq_pri;
		643	my $grp = aio_group $cb;
		644
		645	aioreq_pri $pri;
		646	add $grp aio_rename $src, $dst, sub {
		647	if ($_[0] && $! == EXDEV) {
		648	aioreq_pri $pri;
		649	add $grp aio_copy $src, $dst, sub {
		650	$grp->result ($_[0]);
		651
		652	if (!$_[0]) {
		653	aioreq_pri $pri;
		654	add $grp aio_unlink $src;
		655	}
		656	};
		657	} else {
		658	$grp->result ($_[0]);
		659	}
		660	};
		661
		662	$grp
		663	}
		664	}
		665
377	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	666	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
378		667
379	Scans a directory (similar to C<aio_readdir>) but additionally tries to	668	Scans a directory (similar to C<aio_readdir>) but additionally tries to
380	separate the entries of directory C<$path> into two sets of names, ones	669	efficiently separate the entries of directory C<$path> into two sets of
381	you can recurse into (directories or links to them), and ones you cannot	670	names, directories you can recurse into (directories), and ones you cannot
382	recurse into (everything else).	671	recurse into (everything else, including symlinks to directories).
383		672
384	C<aio_scandir> is a composite request that creates of many sub requests_	673	C<aio_scandir> is a composite request that creates of many sub requests_
385	C<$maxreq> specifies the maximum number of outstanding aio requests that	674	C<$maxreq> specifies the maximum number of outstanding aio requests that
386	this function generates. If it is C<< <= 0 >>, then a suitable default	675	this function generates. If it is C<< <= 0 >>, then a suitable default
387	will be chosen (currently 6).	676	will be chosen (currently 4).
388		677
389	On error, the callback is called without arguments, otherwise it receives	678	On error, the callback is called without arguments, otherwise it receives
390	two array-refs with path-relative entry names.	679	two array-refs with path-relative entry names.
391		680
392	Example:	681	Example:
…		…
426	as those tend to return 0 or 1 as link counts, which disables the	715	as those tend to return 0 or 1 as link counts, which disables the
427	directory counting heuristic.	716	directory counting heuristic.
428		717
429	=cut	718	=cut
430		719
431	sub aio_scandir($$$) {	720	sub aio_scandir($$;$) {
		721	aio_block {
432	my ($path, $maxreq, $cb) = @_;	722	my ($path, $maxreq, $cb) = @_;
433		723
		724	my $pri = aioreq_pri;
		725
434	my $grp = aio_group $cb;	726	my $grp = aio_group $cb;
435		727
436	$maxreq = 6 if $maxreq <= 0;	728	$maxreq = 4 if $maxreq <= 0;
437		729
438	# stat once	730	# stat once
		731	aioreq_pri $pri;
439	add $grp aio_stat $path, sub {	732	add $grp aio_stat $path, sub {
440	return $grp->result () if $_[0];	733	return $grp->result () if $_[0];
441	my $now = time;	734	my $now = time;
442	my $hash1 = join ":", (stat _)[0,1,3,7,9];	735	my $hash1 = join ":", (stat _)[0,1,3,7,9];
443		736
444	# read the directory entries	737	# read the directory entries
		738	aioreq_pri $pri;
445	add $grp aio_readdir $path, sub {	739	add $grp aio_readdir $path, sub {
446	my $entries = shift	740	my $entries = shift
447	or return $grp->result ();	741	or return $grp->result ();
448		742
449	# stat the dir another time	743	# stat the dir another time
		744	aioreq_pri $pri;
450	add $grp aio_stat $path, sub {	745	add $grp aio_stat $path, sub {
451	my $hash2 = join ":", (stat _)[0,1,3,7,9];	746	my $hash2 = join ":", (stat _)[0,1,3,7,9];
452		747
453	my $ndirs;	748	my $ndirs;
454		749
455	# take the slow route if anything looks fishy	750	# take the slow route if anything looks fishy
456	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	751	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
457	$ndirs = -1;	752	$ndirs = -1;
458	} else {	753	} else {
459	# if nlink == 2, we are finished	754	# if nlink == 2, we are finished
460	# on non-posix-fs's, we rely on nlink < 2	755	# on non-posix-fs's, we rely on nlink < 2
461	$ndirs = (stat _)[3] - 2	756	$ndirs = (stat _)[3] - 2
462	or return $grp->result ([], $entries);	757	or return $grp->result ([], $entries);
463	}	758	}
464		759
465	# sort into likely dirs and likely nondirs	760	# sort into likely dirs and likely nondirs
466	# dirs == files without ".", short entries first	761	# dirs == files without ".", short entries first
467	$entries = [map $_->[0],	762	$entries = [map $_->[0],
468	sort { $b->[1] cmp $a->[1] }	763	sort { $b->[1] cmp $a->[1] }
469	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	764	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
470	@$entries];	765	@$entries];
471		766
472	my (@dirs, @nondirs);	767	my (@dirs, @nondirs);
473		768
474	my ($statcb, $schedcb);
475	my $nreq = 0;
476
477	my $statgrp = add $grp aio_group;	769	my $statgrp = add $grp aio_group sub {
478
479	$schedcb = sub {
480	if (@$entries) {
481	if ($nreq < $maxreq) {
482	my $ent = pop @$entries;
483	$nreq++;
484	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
485	}
486	} elsif (!$nreq) {
487	# finished
488	$statgrp->cancel;
489	undef $statcb;
490	undef $schedcb;
491	$grp->result (\@dirs, \@nondirs);	770	$grp->result (\@dirs, \@nondirs);
492	}	771	};
		772
		773	limit $statgrp $maxreq;
		774	feed $statgrp sub {
		775	return unless @$entries;
		776	my $entry = pop @$entries;
		777
		778	aioreq_pri $pri;
		779	add $statgrp aio_stat "$path/$entry/.", sub {
		780	if ($_[0] < 0) {
		781	push @nondirs, $entry;
		782	} else {
		783	# need to check for real directory
		784	aioreq_pri $pri;
		785	add $statgrp aio_lstat "$path/$entry", sub {
		786	if (-d _) {
		787	push @dirs, $entry;
		788
		789	unless (--$ndirs) {
		790	push @nondirs, @$entries;
		791	feed $statgrp;
		792	}
		793	} else {
		794	push @nondirs, $entry;
		795	}
		796	}
		797	}
		798	};
		799	};
493	};	800	};
494	$statcb = sub {
495	my ($status, $entry) = @_;
496
497	if ($status < 0) {
498	$nreq--;
499	push @nondirs, $entry;
500	&$schedcb;
501	} else {
502	# need to check for real directory
503	add $grp aio_lstat "$path/$entry", sub {
504	$nreq--;
505
506	if (-d _) {
507	push @dirs, $entry;
508
509	if (!--$ndirs) {
510	push @nondirs, @$entries;
511	$entries = [];
512	}
513	} else {
514	push @nondirs, $entry;
515	}
516
517	&$schedcb;
518	}
519	}
520	};
521
522	&$schedcb while @$entries && $nreq < $maxreq;
523	};	801	};
524	};	802	};
		803
		804	$grp
525	};	805	}
		806	}
526		807
		808	=item aio_rmtree $path, $callback->($status)
		809
		810	Delete a directory tree starting (and including) C<$path>, return the
		811	status of the final C<rmdir> only. This is a composite request that
		812	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		813	everything else.
		814
		815	=cut
		816
		817	sub aio_rmtree;
		818	sub aio_rmtree($;$) {
		819	aio_block {
		820	my ($path, $cb) = @_;
		821
		822	my $pri = aioreq_pri;
		823	my $grp = aio_group $cb;
		824
		825	aioreq_pri $pri;
		826	add $grp aio_scandir $path, 0, sub {
		827	my ($dirs, $nondirs) = @_;
		828
		829	my $dirgrp = aio_group sub {
		830	add $grp aio_rmdir $path, sub {
		831	$grp->result ($_[0]);
		832	};
		833	};
		834
		835	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		836	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		837
		838	add $grp $dirgrp;
		839	};
		840
527	$grp	841	$grp
		842	}
528	}	843	}
529		844
530	=item aio_fsync $fh, $callback->($status)	845	=item aio_fsync $fh, $callback->($status)
531		846
532	Asynchronously call fsync on the given filehandle and call the callback	847	Asynchronously call fsync on the given filehandle and call the callback
…		…
539		854
540	If this call isn't available because your OS lacks it or it couldn't be	855	If this call isn't available because your OS lacks it or it couldn't be
541	detected, it will be emulated by calling C<fsync> instead.	856	detected, it will be emulated by calling C<fsync> instead.
542		857
543	=item aio_group $callback->(...)	858	=item aio_group $callback->(...)
544
545	[EXPERIMENTAL]
546		859
547	This is a very special aio request: Instead of doing something, it is a	860	This is a very special aio request: Instead of doing something, it is a
548	container for other aio requests, which is useful if you want to bundle	861	container for other aio requests, which is useful if you want to bundle
549	many requests into a single, composite, request with a definite callback	862	many requests into a single, composite, request with a definite callback
550	and the ability to cancel the whole request with its subrequests.	863	and the ability to cancel the whole request with its subrequests.
…		…
591	=head2 IO::AIO::REQ CLASS	904	=head2 IO::AIO::REQ CLASS
592		905
593	All non-aggregate C<aio_*> functions return an object of this class when	906	All non-aggregate C<aio_*> functions return an object of this class when
594	called in non-void context.	907	called in non-void context.
595		908
596	A request always moves through the following five states in its lifetime,
597	in order: B<ready> (request has been created, but has not been executed
598	yet), B<execute> (request is currently being executed), B<pending>
599	(request has been executed but callback has not been called yet),
600	B<result> (results are being processed synchronously, includes calling the
601	callback) and B<done> (request has reached the end of its lifetime and
602	holds no resources anymore).
603
604	=over 4	909	=over 4
605		910
606	=item cancel $req	911	=item cancel $req
607		912
608	Cancels the request, if possible. Has the effect of skipping execution	913	Cancels the request, if possible. Has the effect of skipping execution
…		…
661	=item * They can also can also be added to other IO::AIO::GRP objects.	966	=item * They can also can also be added to other IO::AIO::GRP objects.
662		967
663	=item * You must not add requests to a group from within the group callback (or	968	=item * You must not add requests to a group from within the group callback (or
664	any later time).	969	any later time).
665		970
666	=item * This does not harmonise well with C<max_outstanding>, so best do
667	not combine C<aio_group> with it. Groups and feeders are recommended for
668	this kind of concurrency-limiting.
669
670	=back	971	=back
671		972
672	Their lifetime, simplified, looks like this: when they are empty, they	973	Their lifetime, simplified, looks like this: when they are empty, they
673	will finish very quickly. If they contain only requests that are in the	974	will finish very quickly. If they contain only requests that are in the
674	C<done> state, they will also finish. Otherwise they will continue to	975	C<done> state, they will also finish. Otherwise they will continue to
…		…
689	be added, including other groups, as long as you do not create circular	990	be added, including other groups, as long as you do not create circular
690	dependencies.	991	dependencies.
691		992
692	Returns all its arguments.	993	Returns all its arguments.
693		994
		995	=item $grp->cancel_subs
		996
		997	Cancel all subrequests and clears any feeder, but not the group request
		998	itself. Useful when you queued a lot of events but got a result early.
		999
694	=item $grp->result (...)	1000	=item $grp->result (...)
695		1001
696	Set the result value(s) that will be passed to the group callback when all	1002	Set the result value(s) that will be passed to the group callback when all
697	subrequests have finished. By default, no argument will be passed.	1003	subrequests have finished and set thre groups errno to the current value
		1004	of errno (just like calling C<errno> without an error number). By default,
		1005	no argument will be passed and errno is zero.
		1006
		1007	=item $grp->errno ([$errno])
		1008
		1009	Sets the group errno value to C<$errno>, or the current value of errno
		1010	when the argument is missing.
		1011
		1012	Every aio request has an associated errno value that is restored when
		1013	the callback is invoked. This method lets you change this value from its
		1014	default (0).
		1015
		1016	Calling C<result> will also set errno, so make sure you either set C<$!>
		1017	before the call to C<result>, or call c<errno> after it.
698		1018
699	=item feed $grp $callback->($grp)	1019	=item feed $grp $callback->($grp)
700
701	[VERY EXPERIMENTAL]
702		1020
703	Sets a feeder/generator on this group: every group can have an attached	1021	Sets a feeder/generator on this group: every group can have an attached
704	generator that generates requests if idle. The idea behind this is that,	1022	generator that generates requests if idle. The idea behind this is that,
705	although you could just queue as many requests as you want in a group,	1023	although you could just queue as many requests as you want in a group,
706	this might starve other requests for a potentially long time. For	1024	this might starve other requests for a potentially long time. For
…		…
743		1061
744	=back	1062	=back
745		1063
746	=head2 SUPPORT FUNCTIONS	1064	=head2 SUPPORT FUNCTIONS
747		1065
		1066	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1067
748	=over 4	1068	=over 4
749		1069
750	=item $fileno = IO::AIO::poll_fileno	1070	=item $fileno = IO::AIO::poll_fileno
751		1071
752	Return the I<request result pipe file descriptor>. This filehandle must be	1072	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
756		1076
757	See C<poll_cb> for an example.	1077	See C<poll_cb> for an example.
758		1078
759	=item IO::AIO::poll_cb	1079	=item IO::AIO::poll_cb
760		1080
761	Process all outstanding events on the result pipe. You have to call this	1081	Process some outstanding events on the result pipe. You have to call this
762	regularly. Returns the number of events processed. Returns immediately	1082	regularly. Returns the number of events processed. Returns immediately
763	when no events are outstanding.	1083	when no events are outstanding. The amount of events processed depends on
		1084	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1085
		1086	If not all requests were processed for whatever reason, the filehandle
		1087	will still be ready when C<poll_cb> returns.
764		1088
765	Example: Install an Event watcher that automatically calls	1089	Example: Install an Event watcher that automatically calls
766	IO::AIO::poll_cb with high priority:	1090	IO::AIO::poll_cb with high priority:
767		1091
768	Event->io (fd => IO::AIO::poll_fileno,	1092	Event->io (fd => IO::AIO::poll_fileno,
769	poll => 'r', async => 1,	1093	poll => 'r', async => 1,
770	cb => \&IO::AIO::poll_cb);	1094	cb => \&IO::AIO::poll_cb);
771		1095
		1096	=item IO::AIO::max_poll_reqs $nreqs
		1097
		1098	=item IO::AIO::max_poll_time $seconds
		1099
		1100	These set the maximum number of requests (default C<0>, meaning infinity)
		1101	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1102	the maximum amount of time (default C<0>, meaning infinity) spent in
		1103	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1104	of time C<poll_cb> is allowed to use).
		1105
		1106	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1107	syscall per request processed, which is not normally a problem unless your
		1108	callbacks are really really fast or your OS is really really slow (I am
		1109	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1110
		1111	Setting these is useful if you want to ensure some level of
		1112	interactiveness when perl is not fast enough to process all requests in
		1113	time.
		1114
		1115	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1116
		1117	Example: Install an Event watcher that automatically calls
		1118	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1119	program get the CPU sometimes even under high AIO load.
		1120
		1121	# try not to spend much more than 0.1s in poll_cb
		1122	IO::AIO::max_poll_time 0.1;
		1123
		1124	# use a low priority so other tasks have priority
		1125	Event->io (fd => IO::AIO::poll_fileno,
		1126	poll => 'r', nice => 1,
		1127	cb => &IO::AIO::poll_cb);
		1128
772	=item IO::AIO::poll_wait	1129	=item IO::AIO::poll_wait
773		1130
		1131	If there are any outstanding requests and none of them in the result
774	Wait till the result filehandle becomes ready for reading (simply does a	1132	phase, wait till the result filehandle becomes ready for reading (simply
775	C<select> on the filehandle. This is useful if you want to synchronously wait	1133	does a C<select> on the filehandle. This is useful if you want to
776	for some requests to finish).	1134	synchronously wait for some requests to finish).
777		1135
778	See C<nreqs> for an example.	1136	See C<nreqs> for an example.
779		1137
		1138	=item IO::AIO::poll
		1139
		1140	Waits until some requests have been handled.
		1141
		1142	Returns the number of requests processed, but is otherwise strictly
		1143	equivalent to:
		1144
		1145	IO::AIO::poll_wait, IO::AIO::poll_cb
		1146
780	=item IO::AIO::nreqs	1147	=item IO::AIO::flush
781		1148
782	Returns the number of requests currently outstanding (i.e. for which their	1149	Wait till all outstanding AIO requests have been handled.
783	callback has not been invoked yet).
784		1150
785	Example: wait till there are no outstanding requests anymore:	1151	Strictly equivalent to:
786		1152
787	IO::AIO::poll_wait, IO::AIO::poll_cb	1153	IO::AIO::poll_wait, IO::AIO::poll_cb
788	while IO::AIO::nreqs;	1154	while IO::AIO::nreqs;
789		1155
790	=item IO::AIO::flush	1156	=back
791		1157
792	Wait till all outstanding AIO requests have been handled.	1158	=head3 CONTROLLING THE NUMBER OF THREADS
793		1159
794	Strictly equivalent to:	1160	=over
795
796	IO::AIO::poll_wait, IO::AIO::poll_cb
797	while IO::AIO::nreqs;
798
799	=item IO::AIO::poll
800
801	Waits until some requests have been handled.
802
803	Strictly equivalent to:
804
805	IO::AIO::poll_wait, IO::AIO::poll_cb
806	if IO::AIO::nreqs;
807		1161
808	=item IO::AIO::min_parallel $nthreads	1162	=item IO::AIO::min_parallel $nthreads
809		1163
810	Set the minimum number of AIO threads to C<$nthreads>. The current	1164	Set the minimum number of AIO threads to C<$nthreads>. The current
811	default is C<8>, which means eight asynchronous operations can execute	1165	default is C<8>, which means eight asynchronous operations can execute
812	concurrently at any one time (the number of outstanding requests,	1166	concurrently at any one time (the number of outstanding requests,
813	however, is unlimited).	1167	however, is unlimited).
814		1168
815	IO::AIO starts threads only on demand, when an AIO request is queued and	1169	IO::AIO starts threads only on demand, when an AIO request is queued and
816	no free thread exists.	1170	no free thread exists. Please note that queueing up a hundred requests can
		1171	create demand for a hundred threads, even if it turns out that everything
		1172	is in the cache and could have been processed faster by a single thread.
817		1173
818	It is recommended to keep the number of threads relatively low, as some	1174	It is recommended to keep the number of threads relatively low, as some
819	Linux kernel versions will scale negatively with the number of threads	1175	Linux kernel versions will scale negatively with the number of threads
820	(higher parallelity => MUCH higher latency). With current Linux 2.6	1176	(higher parallelity => MUCH higher latency). With current Linux 2.6
821	versions, 4-32 threads should be fine.	1177	versions, 4-32 threads should be fine.
…		…
835	This module automatically runs C<max_parallel 0> at program end, to ensure	1191	This module automatically runs C<max_parallel 0> at program end, to ensure
836	that all threads are killed and that there are no outstanding requests.	1192	that all threads are killed and that there are no outstanding requests.
837		1193
838	Under normal circumstances you don't need to call this function.	1194	Under normal circumstances you don't need to call this function.
839		1195
		1196	=item IO::AIO::max_idle $nthreads
		1197
		1198	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1199	threads that did not get a request to process within 10 seconds). That
		1200	means if a thread becomes idle while C<$nthreads> other threads are also
		1201	idle, it will free its resources and exit.
		1202
		1203	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1204	to allow for extremely high load situations, but want to free resources
		1205	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1206
		1207	The default is probably ok in most situations, especially if thread
		1208	creation is fast. If thread creation is very slow on your system you might
		1209	want to use larger values.
		1210
840	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1211	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
841		1212
842	[DEPRECATED]	1213	This is a very bad function to use in interactive programs because it
		1214	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1215	use an C<aio_group> together with a feed callback.
843		1216
844	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1217	Sets the maximum number of outstanding requests to C<$nreqs>. If you
845	try to queue up more than this number of requests, the caller will block until	1218	do queue up more than this number of requests, the next call to the
846	some requests have been handled.	1219	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1220	function will block until the limit is no longer exceeded.
847		1221
848	The default is very large, so normally there is no practical limit. If you	1222	The default value is very large, so there is no practical limit on the
849	queue up many requests in a loop it often improves speed if you set	1223	number of outstanding requests.
850	this to a relatively low number, such as C<100>.
851		1224
852	This function does not work well together with C<aio_group>'s, and their	1225	You can still queue as many requests as you want. Therefore,
853	feeder interface is better suited to limiting concurrency, so do not use	1226	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
854	this function.	1227	as a stop gap to shield against fatal memory overflow (with large values).
855
856	Under normal circumstances you don't need to call this function.
857		1228
858	=back	1229	=back
859		1230
		1231	=head3 STATISTICAL INFORMATION
		1232
		1233	=over
		1234
		1235	=item IO::AIO::nreqs
		1236
		1237	Returns the number of requests currently in the ready, execute or pending
		1238	states (i.e. for which their callback has not been invoked yet).
		1239
		1240	Example: wait till there are no outstanding requests anymore:
		1241
		1242	IO::AIO::poll_wait, IO::AIO::poll_cb
		1243	while IO::AIO::nreqs;
		1244
		1245	=item IO::AIO::nready
		1246
		1247	Returns the number of requests currently in the ready state (not yet
		1248	executed).
		1249
		1250	=item IO::AIO::npending
		1251
		1252	Returns the number of requests currently in the pending state (executed,
		1253	but not yet processed by poll_cb).
		1254
		1255	=back
		1256
860	=cut	1257	=cut
861		1258
862	# support function to convert a fd into a perl filehandle
863	sub _fd2fh {
864	return undef if $_[0] < 0;
865
866	# try to generate nice filehandles
867	my $sym = "IO::AIO::fd#$_[0]";
868	local *$sym;
869
870	open *$sym, "+<&=$_[0]" # usually works under any unix
871	or open *$sym, "<&=$_[0]" # cygwin needs this
872	or open *$sym, ">&=$_[0]" # or this
873	or return undef;
874
875	*$sym
876	}
877
878	min_parallel 8;	1259	min_parallel 8;
879		1260
880	END {	1261	END { flush }
881	max_parallel 0;
882	}
883		1262
884	1;	1263	1;
885		1264
886	=head2 FORK BEHAVIOUR	1265	=head2 FORK BEHAVIOUR
887		1266
888	This module should do "the right thing" when the process using it forks:	1267	This module should do "the right thing" when the process using it forks:
889		1268
890	Before the fork, IO::AIO enters a quiescent state where no requests	1269	Before the fork, IO::AIO enters a quiescent state where no requests
891	can be added in other threads and no results will be processed. After	1270	can be added in other threads and no results will be processed. After
892	the fork the parent simply leaves the quiescent state and continues	1271	the fork the parent simply leaves the quiescent state and continues
893	request/result processing, while the child clears the request/result	1272	request/result processing, while the child frees the request/result queue
894	queue (so the requests started before the fork will only be handled in	1273	(so that the requests started before the fork will only be handled in the
895	the parent). Threads will be started on demand until the limit ste in the	1274	parent). Threads will be started on demand until the limit set in the
896	parent process has been reached again.	1275	parent process has been reached again.
897		1276
898	In short: the parent will, after a short pause, continue as if fork had	1277	In short: the parent will, after a short pause, continue as if fork had
899	not been called, while the child will act as if IO::AIO has not been used	1278	not been called, while the child will act as if IO::AIO has not been used
900	yet.	1279	yet.
901		1280
902	=head2 MEMORY USAGE	1281	=head2 MEMORY USAGE
903		1282
		1283	Per-request usage:
		1284
904	Each aio request uses - depending on your architecture - around 128 bytes	1285	Each aio request uses - depending on your architecture - around 100-200
905	of memory. In addition, stat requests need a stat buffer (possibly a few	1286	bytes of memory. In addition, stat requests need a stat buffer (possibly
906	hundred bytes). Perl scalars and other data passed into aio requests will	1287	a few hundred bytes), readdir requires a result buffer and so on. Perl
907	also be locked.	1288	scalars and other data passed into aio requests will also be locked and
		1289	will consume memory till the request has entered the done state.
908		1290
909	This is now awfully much, so queuing lots of requests is not usually a	1291	This is not awfully much, so queuing lots of requests is not usually a
910	problem.	1292	problem.
911		1293
912	Each thread needs a stack area which is usually around 16k, sometimes much	1294	Per-thread usage:
913	larger, depending on the OS.	1295
		1296	In the execution phase, some aio requests require more memory for
		1297	temporary buffers, and each thread requires a stack and other data
		1298	structures (usually around 16k-128k, depending on the OS).
		1299
		1300	=head1 KNOWN BUGS
		1301
		1302	Known bugs will be fixed in the next release.
914		1303
915	=head1 SEE ALSO	1304	=head1 SEE ALSO
916		1305
917	L<Coro::AIO>.	1306	L<Coro::AIO>.
918		1307

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs. Revision 1.116 by root, Wed Oct 3 21:27:51 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.116 by root, Wed Oct 3 21:27:51 2007 UTC