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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.60 by root, Sun Oct 22 13:33:28 2006 UTC vs.
Revision 1.108 by root, Fri Jun 1 13:25:50 2007 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
18	};	19	};
19		20
20	# version 2+ has request and group objects	21	# version 2+ has request and group objects
21	use IO::AIO 2;	22	use IO::AIO 2;
22		23
		24	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
25		27
26	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
…		…
50	=head1 DESCRIPTION	52	=head1 DESCRIPTION
51		53
52	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
53	operating system supports.	55	operating system supports.
54		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for
		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
55	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
56	and signal their completion. You don't need thread support in your libc or	74	requests and signal their completion. You don't need thread support
57	perl, and the threads created by this module will not be visible to the	75	in perl, and the threads created by this module will not be visible
58	pthreads library. In the future, this module might make use of the native	76	to perl. In the future, this module might make use of the native aio
59	aio functions available on many operating systems. However, they are often	77	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	79	files currently, for example), and they would only support aio_read and
62	remaining 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.
63		82
64	Although the module will work with in the presence of other threads, it is	83	Although the module will work in the presence of other (Perl-) threads,
65	currently not reentrant, so use appropriate locking yourself, always call	84	it is currently not reentrant in any way, so use appropriate locking
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	85	yourself, always call C<poll_cb> from within the same thread, or never
67	C<aio_> functions) recursively.	86	call C<poll_cb> (or other C<aio_> functions) recursively.
		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
68		183
69	=cut	184	=cut
70		185
71	package IO::AIO;	186	package IO::AIO;
72		187
…		…
74	use strict 'vars';	189	use strict 'vars';
75		190
76	use base 'Exporter';	191	use base 'Exporter';
77		192
78	BEGIN {	193	BEGIN {
79	our $VERSION = '2.0';	194	our $VERSION = '2.4';
80		195
81	our @EXPORT = 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
82	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
83	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
84	aio_group);	199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	200	aio_chown aio_chmod aio_utime);
		201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
		202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
86		206
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		208
89	require XSLoader;	209	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
91	}	211	}
92		212
93	=head1 FUNCTIONS	213	=head1 FUNCTIONS
94		214
95	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
96		216
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
100	which must be a code reference. This code reference will get called with	220	which must be a code reference. This code reference will get called with
…		…
103	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
104		224
105	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	226	internally until the request has finished.
107		227
108	All requests return objects of type L<IO::AIO::REQ> that allow further	228	All functions return request objects of type L<IO::AIO::REQ> that allow
109	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
110		230
111	The pathnames you pass to these routines I<must> be absolute and	231	The pathnames you pass to these routines I<must> be absolute and
112	encoded in byte form. The reason for the former is that at the time the	232	encoded as octets. The reason for the former is that at the time the
113	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
115	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
116		237
117	To encode pathnames to byte form, either make sure you either: a)	238	To encode pathnames as octets, either make sure you either: a) always pass
118	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
119	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
120	your pathnames to the locale (or other) encoding in effect in the user	241	your pathnames to the locale (or other) encoding in effect in the user
121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	use something else.	243	use something else to ensure your scalar has the correct contents.
		244
		245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		246	handles correctly wether it is set or not.
123		247
124	=over 4	248	=over 4
		249
		250	=item $prev_pri = aioreq_pri [$pri]
		251
		252	Returns the priority value that would be used for the next request and, if
		253	C<$pri> is given, sets the priority for the next aio request.
		254
		255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
		258
		259	The priority will be reset to C<0> after each call to one of the C<aio_*>
		260	functions.
		261
		262	Example: open a file with low priority, then read something from it with
		263	higher priority so the read request is serviced before other low priority
		264	open requests (potentially spamming the cache):
		265
		266	aioreq_pri -3;
		267	aio_open ..., sub {
		268	return unless $_[0];
		269
		270	aioreq_pri -2;
		271	aio_read $_[0], ..., sub {
		272	...
		273	};
		274	};
		275
		276
		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
125		282
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		284
128	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
129	created filehandle for the file.	286	created filehandle for the file.
…		…
135	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
136		293
137	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
138	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>,
139	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,
140	and C<0666> or C<0777> if you do).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
141		300
142	Example:	301	Example:
143		302
144	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
145	if ($_[0]) {	304	if ($_[0]) {
…		…
148	} else {	307	} else {
149	die "open failed: $!\n";	308	die "open failed: $!\n";
150	}	309	}
151	};	310	};
152		311
		312
153	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
154		314
155	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
156	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
157	filehandle here, as perl will likely close the file descriptor another	317	filehandle here, as perl will likely close the file descriptor another
…		…
159	C<close> or just let filehandles go out of scope.	319	C<close> or just let filehandles go out of scope.
160		320
161	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
162	therefore best to avoid this function.	322	therefore best to avoid this function.
163		323
		324
164	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
165		326
166	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	327	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		328
168	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>
169	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
170	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
171	like the syscall).	332	like the syscall). If C<offset> is undefined, then the current file offset
		333	will be used (and updated), otherwise the file offset will not be changed
		334	by these calls.
172		335
173	The C<$data> scalar I<MUST NOT> be modified in any way while the request	336	The C<$data> scalar I<MUST NOT> be modified in any way while the request
174	is outstanding. Modifying it can result in segfaults or WW3 (if the	337	is outstanding. Modifying it can result in segfaults or World War III (if
175	necessary/optional hardware is installed).	338	the necessary/optional hardware is installed).
176		339
177	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	340	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
178	offset C<0> within the scalar:	341	offset C<0> within the scalar:
179		342
180	aio_read $fh, 7, 15, $buffer, 0, sub {	343	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	344	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	345	print "read $_[0] bytes: <$buffer>\n";
183	};	346	};
184		347
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	[EXPERIMENTAL due to internal aio_group use]
188
189	Try to move the I<file> (directories not supported as either source or
190	destination) from C<$srcpath> to C<$dstpath> and call the callback with
191	the C<0> (error) or C<-1> ok.
192
193	This is a composite request that tries to rename(2) the file first. If
194	rename files with C<EXDEV>, it creates the destination file with mode 0200
195	and copies the contents of the source file into it using C<aio_sendfile>,
196	followed by restoring atime, mtime, access mode and uid/gid, in that
197	order, and unlinking the C<$srcpath>.
198
199	If an error occurs, the partial destination file will be unlinked, if
200	possible, except when setting atime, mtime, access mode and uid/gid, where
201	errors are being ignored.
202
203	=cut
204
205	sub aio_move($$$) {
206	my ($src, $dst, $cb) = @_;
207
208	my $grp = aio_group $cb;
209
210	add $grp aio_rename $src, $dst, sub {
211	if ($_[0] && $! == EXDEV) {
212	add $grp aio_open $src, O_RDONLY, 0, sub {
213	if (my $src_fh = $_[0]) {
214	my @stat = stat $src_fh;
215
216	add $grp aio_open $dst, O_WRONLY, 0200, sub {
217	if (my $dst_fh = $_[0]) {
218	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
219	close $src_fh;
220
221	if ($_[0] == $stat[7]) {
222	utime $stat[8], $stat[9], $dst;
223	chmod $stat[2] & 07777, $dst_fh;
224	chown $stat[4], $stat[5], $dst_fh;
225	close $dst_fh;
226
227	add $grp aio_unlink $src, sub {
228	$grp->result ($_[0]);
229	};
230	} else {
231	my $errno = $!;
232	add $grp aio_unlink $dst, sub {
233	$! = $errno;
234	$grp->result (-1);
235	};
236	}
237	};
238	} else {
239	$grp->result (-1);
240	}
241	},
242
243	} else {
244	$grp->result (-1);
245	}
246	};
247	} else {
248	$grp->result ($_[0]);
249	}
250	};
251
252	$grp
253	}
254		348
255	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	349	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
256		350
257	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	351	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
258	reading at byte offset C<$in_offset>, and starts writing at the current	352	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
272	C<$in_fh> than are written, and there is no way to find out how many	366	C<$in_fh> than are written, and there is no way to find out how many
273	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	367	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
274	provides the number of bytes written to C<$out_fh>. Only if the result	368	provides the number of bytes written to C<$out_fh>. Only if the result
275	value equals C<$length> one can assume that C<$length> bytes have been	369	value equals C<$length> one can assume that C<$length> bytes have been
276	read.	370	read.
		371
277		372
278	=item aio_readahead $fh,$offset,$length, $callback->($retval)	373	=item aio_readahead $fh,$offset,$length, $callback->($retval)
279		374
280	C<aio_readahead> populates the page cache with data from a file so that	375	C<aio_readahead> populates the page cache with data from a file so that
281	subsequent reads from that file will not block on disk I/O. The C<$offset>	376	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
287	file. The current file offset of the file is left unchanged.	382	file. The current file offset of the file is left unchanged.
288		383
289	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	384	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
290	emulated by simply reading the data, which would have a similar effect.	385	emulated by simply reading the data, which would have a similar effect.
291		386
		387
292	=item aio_stat $fh_or_path, $callback->($status)	388	=item aio_stat $fh_or_path, $callback->($status)
293		389
294	=item aio_lstat $fh, $callback->($status)	390	=item aio_lstat $fh, $callback->($status)
295		391
296	Works like perl's C<stat> or C<lstat> in void context. The callback will	392	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
309	aio_stat "/etc/passwd", sub {	405	aio_stat "/etc/passwd", sub {
310	$_[0] and die "stat failed: $!";	406	$_[0] and die "stat failed: $!";
311	print "size is ", -s _, "\n";	407	print "size is ", -s _, "\n";
312	};	408	};
313		409
		410
		411	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		412
		413	Works like perl's C<utime> function (including the special case of $atime
		414	and $mtime being undef). Fractional times are supported if the underlying
		415	syscalls support them.
		416
		417	When called with a pathname, uses utimes(2) if available, otherwise
		418	utime(2). If called on a file descriptor, uses futimes(2) if available,
		419	otherwise returns ENOSYS, so this is not portable.
		420
		421	Examples:
		422
		423	# set atime and mtime to current time (basically touch(1)):
		424	aio_utime "path", undef, undef;
		425	# set atime to current time and mtime to beginning of the epoch:
		426	aio_utime "path", time, undef; # undef==0
		427
		428
		429	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		430
		431	Works like perl's C<chown> function, except that C<undef> for either $uid
		432	or $gid is being interpreted as "do not change" (but -1 can also be used).
		433
		434	Examples:
		435
		436	# same as "chown root path" in the shell:
		437	aio_chown "path", 0, -1;
		438	# same as above:
		439	aio_chown "path", 0, undef;
		440
		441
		442	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		443
		444	Works like perl's C<chmod> function.
		445
		446
314	=item aio_unlink $pathname, $callback->($status)	447	=item aio_unlink $pathname, $callback->($status)
315		448
316	Asynchronously unlink (delete) a file and call the callback with the	449	Asynchronously unlink (delete) a file and call the callback with the
317	result code.	450	result code.
318		451
		452
		453	=item aio_mknod $path, $mode, $dev, $callback->($status)
		454
		455	[EXPERIMENTAL]
		456
		457	Asynchronously create a device node (or fifo). See mknod(2).
		458
		459	The only (POSIX-) portable way of calling this function is:
		460
		461	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		462
		463
319	=item aio_link $srcpath, $dstpath, $callback->($status)	464	=item aio_link $srcpath, $dstpath, $callback->($status)
320		465
321	Asynchronously create a new link to the existing object at C<$srcpath> at	466	Asynchronously create a new link to the existing object at C<$srcpath> at
322	the path C<$dstpath> and call the callback with the result code.	467	the path C<$dstpath> and call the callback with the result code.
323		468
		469
324	=item aio_symlink $srcpath, $dstpath, $callback->($status)	470	=item aio_symlink $srcpath, $dstpath, $callback->($status)
325		471
326	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	472	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
327	the path C<$dstpath> and call the callback with the result code.	473	the path C<$dstpath> and call the callback with the result code.
328		474
		475
		476	=item aio_readlink $path, $callback->($link)
		477
		478	Asynchronously read the symlink specified by C<$path> and pass it to
		479	the callback. If an error occurs, nothing or undef gets passed to the
		480	callback.
		481
		482
329	=item aio_rename $srcpath, $dstpath, $callback->($status)	483	=item aio_rename $srcpath, $dstpath, $callback->($status)
330		484
331	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	485	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
332	rename(2) and call the callback with the result code.	486	rename(2) and call the callback with the result code.
333		487
		488
		489	=item aio_mkdir $pathname, $mode, $callback->($status)
		490
		491	Asynchronously mkdir (create) a directory and call the callback with
		492	the result code. C<$mode> will be modified by the umask at the time the
		493	request is executed, so do not change your umask.
		494
		495
334	=item aio_rmdir $pathname, $callback->($status)	496	=item aio_rmdir $pathname, $callback->($status)
335		497
336	Asynchronously rmdir (delete) a directory and call the callback with the	498	Asynchronously rmdir (delete) a directory and call the callback with the
337	result code.	499	result code.
		500
338		501
339	=item aio_readdir $pathname, $callback->($entries)	502	=item aio_readdir $pathname, $callback->($entries)
340		503
341	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	504	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
342	directory (i.e. opendir + readdir + closedir). The entries will not be	505	directory (i.e. opendir + readdir + closedir). The entries will not be
343	sorted, and will B<NOT> include the C<.> and C<..> entries.	506	sorted, and will B<NOT> include the C<.> and C<..> entries.
344		507
345	The callback a single argument which is either C<undef> or an array-ref	508	The callback a single argument which is either C<undef> or an array-ref
346	with the filenames.	509	with the filenames.
347		510
		511
		512	=item aio_load $path, $data, $callback->($status)
		513
		514	This is a composite request that tries to fully load the given file into
		515	memory. Status is the same as with aio_read.
		516
		517	=cut
		518
		519	sub aio_load($$;$) {
		520	aio_block {
		521	my ($path, undef, $cb) = @_;
		522	my $data = \$_[1];
		523
		524	my $pri = aioreq_pri;
		525	my $grp = aio_group $cb;
		526
		527	aioreq_pri $pri;
		528	add $grp aio_open $path, O_RDONLY, 0, sub {
		529	my $fh = shift
		530	or return $grp->result (-1);
		531
		532	aioreq_pri $pri;
		533	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		534	$grp->result ($_[0]);
		535	};
		536	};
		537
		538	$grp
		539	}
		540	}
		541
		542	=item aio_copy $srcpath, $dstpath, $callback->($status)
		543
		544	Try to copy the I<file> (directories not supported as either source or
		545	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		546	the C<0> (error) or C<-1> ok.
		547
		548	This is a composite request that it creates the destination file with
		549	mode 0200 and copies the contents of the source file into it using
		550	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		551	uid/gid, in that order.
		552
		553	If an error occurs, the partial destination file will be unlinked, if
		554	possible, except when setting atime, mtime, access mode and uid/gid, where
		555	errors are being ignored.
		556
		557	=cut
		558
		559	sub aio_copy($$;$) {
		560	aio_block {
		561	my ($src, $dst, $cb) = @_;
		562
		563	my $pri = aioreq_pri;
		564	my $grp = aio_group $cb;
		565
		566	aioreq_pri $pri;
		567	add $grp aio_open $src, O_RDONLY, 0, sub {
		568	if (my $src_fh = $_[0]) {
		569	my @stat = stat $src_fh;
		570
		571	aioreq_pri $pri;
		572	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		573	if (my $dst_fh = $_[0]) {
		574	aioreq_pri $pri;
		575	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		576	if ($_[0] == $stat[7]) {
		577	$grp->result (0);
		578	close $src_fh;
		579
		580	# those should not normally block. should. should.
		581	utime $stat[8], $stat[9], $dst;
		582	chmod $stat[2] & 07777, $dst_fh;
		583	chown $stat[4], $stat[5], $dst_fh;
		584	close $dst_fh;
		585	} else {
		586	$grp->result (-1);
		587	close $src_fh;
		588	close $dst_fh;
		589
		590	aioreq $pri;
		591	add $grp aio_unlink $dst;
		592	}
		593	};
		594	} else {
		595	$grp->result (-1);
		596	}
		597	},
		598
		599	} else {
		600	$grp->result (-1);
		601	}
		602	};
		603
		604	$grp
		605	}
		606	}
		607
		608	=item aio_move $srcpath, $dstpath, $callback->($status)
		609
		610	Try to move the I<file> (directories not supported as either source or
		611	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		612	the C<0> (error) or C<-1> ok.
		613
		614	This is a composite request that tries to rename(2) the file first. If
		615	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		616	that is successful, unlinking the C<$srcpath>.
		617
		618	=cut
		619
		620	sub aio_move($$;$) {
		621	aio_block {
		622	my ($src, $dst, $cb) = @_;
		623
		624	my $pri = aioreq_pri;
		625	my $grp = aio_group $cb;
		626
		627	aioreq_pri $pri;
		628	add $grp aio_rename $src, $dst, sub {
		629	if ($_[0] && $! == EXDEV) {
		630	aioreq_pri $pri;
		631	add $grp aio_copy $src, $dst, sub {
		632	$grp->result ($_[0]);
		633
		634	if (!$_[0]) {
		635	aioreq_pri $pri;
		636	add $grp aio_unlink $src;
		637	}
		638	};
		639	} else {
		640	$grp->result ($_[0]);
		641	}
		642	};
		643
		644	$grp
		645	}
		646	}
		647
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	648	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		649
350	[EXPERIMENTAL due to internal aio_group use]
351
352	Scans a directory (similar to C<aio_readdir>) but additionally tries to	650	Scans a directory (similar to C<aio_readdir>) but additionally tries to
353	separate the entries of directory C<$path> into two sets of names, ones	651	efficiently separate the entries of directory C<$path> into two sets of
354	you can recurse into (directories or links to them), and ones you cannot	652	names, directories you can recurse into (directories), and ones you cannot
355	recurse into (everything else).	653	recurse into (everything else, including symlinks to directories).
356		654
357	C<aio_scandir> is a composite request that consists of many sub	655	C<aio_scandir> is a composite request that creates of many sub requests_
358	requests. C<$maxreq> specifies the maximum number of outstanding aio	656	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	requests that this function generates. If it is C<< <= 0 >>, then a	657	this function generates. If it is C<< <= 0 >>, then a suitable default
360	suitable default will be chosen (currently 8).	658	will be chosen (currently 4).
361		659
362	On error, the callback is called without arguments, otherwise it receives	660	On error, the callback is called without arguments, otherwise it receives
363	two array-refs with path-relative entry names.	661	two array-refs with path-relative entry names.
364		662
365	Example:	663	Example:
…		…
399	as those tend to return 0 or 1 as link counts, which disables the	697	as those tend to return 0 or 1 as link counts, which disables the
400	directory counting heuristic.	698	directory counting heuristic.
401		699
402	=cut	700	=cut
403		701
404	sub aio_scandir($$$) {	702	sub aio_scandir($$;$) {
		703	aio_block {
405	my ($path, $maxreq, $cb) = @_;	704	my ($path, $maxreq, $cb) = @_;
406		705
		706	my $pri = aioreq_pri;
		707
407	my $grp = aio_group $cb;	708	my $grp = aio_group $cb;
408		709
409	$maxreq = 8 if $maxreq <= 0;	710	$maxreq = 4 if $maxreq <= 0;
410		711
411	# stat once	712	# stat once
		713	aioreq_pri $pri;
412	add $grp aio_stat $path, sub {	714	add $grp aio_stat $path, sub {
413	return $grp->result () if $_[0];	715	return $grp->result () if $_[0];
414	my $now = time;	716	my $now = time;
415	my $hash1 = join ":", (stat _)[0,1,3,7,9];	717	my $hash1 = join ":", (stat _)[0,1,3,7,9];
416		718
417	# read the directory entries	719	# read the directory entries
		720	aioreq_pri $pri;
418	add $grp aio_readdir $path, sub {	721	add $grp aio_readdir $path, sub {
419	my $entries = shift	722	my $entries = shift
420	or return $grp->result ();	723	or return $grp->result ();
421		724
422	# stat the dir another time	725	# stat the dir another time
		726	aioreq_pri $pri;
423	add $grp aio_stat $path, sub {	727	add $grp aio_stat $path, sub {
424	my $hash2 = join ":", (stat _)[0,1,3,7,9];	728	my $hash2 = join ":", (stat _)[0,1,3,7,9];
425		729
426	my $ndirs;	730	my $ndirs;
427		731
428	# take the slow route if anything looks fishy	732	# take the slow route if anything looks fishy
429	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	733	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
430	$ndirs = -1;	734	$ndirs = -1;
431	} else {	735	} else {
432	# if nlink == 2, we are finished	736	# if nlink == 2, we are finished
433	# on non-posix-fs's, we rely on nlink < 2	737	# on non-posix-fs's, we rely on nlink < 2
434	$ndirs = (stat _)[3] - 2	738	$ndirs = (stat _)[3] - 2
435	or return $grp->result ([], $entries);	739	or return $grp->result ([], $entries);
436	}	740	}
437		741
438	# sort into likely dirs and likely nondirs	742	# sort into likely dirs and likely nondirs
439	# dirs == files without ".", short entries first	743	# dirs == files without ".", short entries first
440	$entries = [map $_->[0],	744	$entries = [map $_->[0],
441	sort { $b->[1] cmp $a->[1] }	745	sort { $b->[1] cmp $a->[1] }
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	746	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];	747	@$entries];
444		748
445	my (@dirs, @nondirs);	749	my (@dirs, @nondirs);
446		750
447	my ($statcb, $schedcb);
448	my $nreq = 0;
449
450	my $statgrp = add $grp aio_group;	751	my $statgrp = add $grp aio_group sub {
451
452	$schedcb = sub {
453	if (@$entries) {
454	if ($nreq < $maxreq) {
455	my $ent = pop @$entries;
456	$nreq++;
457	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
458	}
459	} elsif (!$nreq) {
460	# finished
461	$statgrp->cancel;
462	undef $statcb;
463	undef $schedcb;
464	$grp->result (\@dirs, \@nondirs);	752	$grp->result (\@dirs, \@nondirs);
465	}	753	};
		754
		755	limit $statgrp $maxreq;
		756	feed $statgrp sub {
		757	return unless @$entries;
		758	my $entry = pop @$entries;
		759
		760	aioreq_pri $pri;
		761	add $statgrp aio_stat "$path/$entry/.", sub {
		762	if ($_[0] < 0) {
		763	push @nondirs, $entry;
		764	} else {
		765	# need to check for real directory
		766	aioreq_pri $pri;
		767	add $statgrp aio_lstat "$path/$entry", sub {
		768	if (-d _) {
		769	push @dirs, $entry;
		770
		771	unless (--$ndirs) {
		772	push @nondirs, @$entries;
		773	feed $statgrp;
		774	}
		775	} else {
		776	push @nondirs, $entry;
		777	}
		778	}
		779	}
		780	};
		781	};
466	};	782	};
467	$statcb = sub {
468	my ($status, $entry) = @_;
469
470	if ($status < 0) {
471	$nreq--;
472	push @nondirs, $entry;
473	&$schedcb;
474	} else {
475	# need to check for real directory
476	add $grp aio_lstat "$path/$entry", sub {
477	$nreq--;
478
479	if (-d _) {
480	push @dirs, $entry;
481
482	if (!--$ndirs) {
483	push @nondirs, @$entries;
484	$entries = [];
485	}
486	} else {
487	push @nondirs, $entry;
488	}
489
490	&$schedcb;
491	}
492	}
493	};
494
495	&$schedcb while @$entries && $nreq < $maxreq;
496	};	783	};
497	};	784	};
		785
		786	$grp
498	};	787	}
		788	}
499		789
		790	=item aio_rmtree $path, $callback->($status)
		791
		792	Delete a directory tree starting (and including) C<$path>, return the
		793	status of the final C<rmdir> only. This is a composite request that
		794	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		795	everything else.
		796
		797	=cut
		798
		799	sub aio_rmtree;
		800	sub aio_rmtree($;$) {
		801	aio_block {
		802	my ($path, $cb) = @_;
		803
		804	my $pri = aioreq_pri;
		805	my $grp = aio_group $cb;
		806
		807	aioreq_pri $pri;
		808	add $grp aio_scandir $path, 0, sub {
		809	my ($dirs, $nondirs) = @_;
		810
		811	my $dirgrp = aio_group sub {
		812	add $grp aio_rmdir $path, sub {
		813	$grp->result ($_[0]);
		814	};
		815	};
		816
		817	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		818	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		819
		820	add $grp $dirgrp;
		821	};
		822
500	$grp	823	$grp
		824	}
501	}	825	}
502		826
503	=item aio_fsync $fh, $callback->($status)	827	=item aio_fsync $fh, $callback->($status)
504		828
505	Asynchronously call fsync on the given filehandle and call the callback	829	Asynchronously call fsync on the given filehandle and call the callback
…		…
513	If this call isn't available because your OS lacks it or it couldn't be	837	If this call isn't available because your OS lacks it or it couldn't be
514	detected, it will be emulated by calling C<fsync> instead.	838	detected, it will be emulated by calling C<fsync> instead.
515		839
516	=item aio_group $callback->(...)	840	=item aio_group $callback->(...)
517		841
518	[EXPERIMENTAL]
519
520	This is a very special aio request: Instead of doing something, it is a	842	This is a very special aio request: Instead of doing something, it is a
521	container for other aio requests, which is useful if you want to bundle	843	container for other aio requests, which is useful if you want to bundle
522	many requests into a single, composite, request.	844	many requests into a single, composite, request with a definite callback
		845	and the ability to cancel the whole request with its subrequests.
523		846
524	Returns an object of class L<IO::AIO::GRP>. See its documentation below	847	Returns an object of class L<IO::AIO::GRP>. See its documentation below
525	for more info.	848	for more info.
526		849
527	Example:	850	Example:
…		…
533	add $grp	856	add $grp
534	(aio_stat ...),	857	(aio_stat ...),
535	(aio_stat ...),	858	(aio_stat ...),
536	...;	859	...;
537		860
		861	=item aio_nop $callback->()
		862
		863	This is a special request - it does nothing in itself and is only used for
		864	side effects, such as when you want to add a dummy request to a group so
		865	that finishing the requests in the group depends on executing the given
		866	code.
		867
		868	While this request does nothing, it still goes through the execution
		869	phase and still requires a worker thread. Thus, the callback will not
		870	be executed immediately but only after other requests in the queue have
		871	entered their execution phase. This can be used to measure request
		872	latency.
		873
538	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	874	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
539		875
540	Mainly used for debugging and benchmarking, this aio request puts one of	876	Mainly used for debugging and benchmarking, this aio request puts one of
541	the request workers to sleep for the given time.	877	the request workers to sleep for the given time.
542		878
543	While it is theoretically handy to have simple I/O scheduling requests	879	While it is theoretically handy to have simple I/O scheduling requests
544	like sleep and file handle readable/writable, the overhead this creates	880	like sleep and file handle readable/writable, the overhead this creates is
545	is immense, so do not use this function except to put your application	881	immense (it blocks a thread for a long time) so do not use this function
546	under artificial I/O pressure.	882	except to put your application under artificial I/O pressure.
547		883
548	=back	884	=back
549		885
550	=head2 IO::AIO::REQ CLASS	886	=head2 IO::AIO::REQ CLASS
551		887
552	All non-aggregate C<aio_*> functions return an object of this class when	888	All non-aggregate C<aio_*> functions return an object of this class when
553	called in non-void context.	889	called in non-void context.
554		890
555	A request always moves through the following five states in its lifetime,
556	in order: B<ready> (request has been created, but has not been executed
557	yet), B<execute> (request is currently being executed), B<pending>
558	(request has been executed but callback has not been called yet),
559	B<result> (results are being processed synchronously, includes calling the
560	callback) and B<done> (request has reached the end of its lifetime and
561	holds no resources anymore).
562
563	=over 4	891	=over 4
564		892
565	=item $req->cancel	893	=item cancel $req
566		894
567	Cancels the request, if possible. Has the effect of skipping execution	895	Cancels the request, if possible. Has the effect of skipping execution
568	when entering the B<execute> state and skipping calling the callback when	896	when entering the B<execute> state and skipping calling the callback when
569	entering the the B<result> state, but will leave the request otherwise	897	entering the the B<result> state, but will leave the request otherwise
570	untouched. That means that requests that currently execute will not be	898	untouched. That means that requests that currently execute will not be
571	stopped and resources held by the request will not be freed prematurely.	899	stopped and resources held by the request will not be freed prematurely.
572		900
		901	=item cb $req $callback->(...)
		902
		903	Replace (or simply set) the callback registered to the request.
		904
573	=back	905	=back
574		906
575	=head2 IO::AIO::GRP CLASS	907	=head2 IO::AIO::GRP CLASS
576		908
577	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	909	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
603	};	935	};
604		936
605	This makes it very easy to create composite requests (see the source of	937	This makes it very easy to create composite requests (see the source of
606	C<aio_move> for an application) that work and feel like simple requests.	938	C<aio_move> for an application) that work and feel like simple requests.
607		939
		940	=over 4
		941
608	The IO::AIO::GRP objects will be cleaned up during calls to	942	=item * The IO::AIO::GRP objects will be cleaned up during calls to
609	C<IO::AIO::poll_cb>, just like any other request.	943	C<IO::AIO::poll_cb>, just like any other request.
610		944
611	They can be canceled like any other request. Canceling will cancel not	945	=item * They can be canceled like any other request. Canceling will cancel not
612	only the request itself, but also all requests it contains.	946	only the request itself, but also all requests it contains.
613		947
614	They can also can also be added to other IO::AIO::GRP objects.	948	=item * They can also can also be added to other IO::AIO::GRP objects.
615		949
616	You must not add requests to a group from within the group callback (or	950	=item * You must not add requests to a group from within the group callback (or
617	any later time).	951	any later time).
		952
		953	=back
618		954
619	Their lifetime, simplified, looks like this: when they are empty, they	955	Their lifetime, simplified, looks like this: when they are empty, they
620	will finish very quickly. If they contain only requests that are in the	956	will finish very quickly. If they contain only requests that are in the
621	C<done> state, they will also finish. Otherwise they will continue to	957	C<done> state, they will also finish. Otherwise they will continue to
622	exist.	958	exist.
…		…
626	group. And only when all those requests have finished will the the group	962	group. And only when all those requests have finished will the the group
627	itself finish.	963	itself finish.
628		964
629	=over 4	965	=over 4
630		966
		967	=item add $grp ...
		968
631	=item $grp->add (...)	969	=item $grp->add (...)
632
633	=item add $grp ...
634		970
635	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	971	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
636	be added, including other groups, as long as you do not create circular	972	be added, including other groups, as long as you do not create circular
637	dependencies.	973	dependencies.
638		974
639	Returns all its arguments.	975	Returns all its arguments.
640		976
		977	=item $grp->cancel_subs
		978
		979	Cancel all subrequests and clears any feeder, but not the group request
		980	itself. Useful when you queued a lot of events but got a result early.
		981
641	=item $grp->result (...)	982	=item $grp->result (...)
642		983
643	Set the result value(s) that will be passed to the group callback when all	984	Set the result value(s) that will be passed to the group callback when all
644	subrequests have finished. By default, no argument will be passed.	985	subrequests have finished and set thre groups errno to the current value
		986	of errno (just like calling C<errno> without an error number). By default,
		987	no argument will be passed and errno is zero.
645		988
646	=item $grp->set_feeder ($callback->($grp))	989	=item $grp->errno ([$errno])
647		990
648	[VERY EXPERIMENTAL]	991	Sets the group errno value to C<$errno>, or the current value of errno
		992	when the argument is missing.
		993
		994	Every aio request has an associated errno value that is restored when
		995	the callback is invoked. This method lets you change this value from its
		996	default (0).
		997
		998	Calling C<result> will also set errno, so make sure you either set C<$!>
		999	before the call to C<result>, or call c<errno> after it.
		1000
		1001	=item feed $grp $callback->($grp)
649		1002
650	Sets a feeder/generator on this group: every group can have an attached	1003	Sets a feeder/generator on this group: every group can have an attached
651	generator that generates requests if idle. The idea behind this is that,	1004	generator that generates requests if idle. The idea behind this is that,
652	although you could just queue as many requests as you want in a group,	1005	although you could just queue as many requests as you want in a group,
653	this might starve other requests for a potentially long time. For	1006	this might starve other requests for a potentially long time. For
654	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1007	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
655	requests, delaying any later requests for a long time.	1008	requests, delaying any later requests for a long time.
656		1009
657	To avoid this, and allow incremental generation of requests, you can	1010	To avoid this, and allow incremental generation of requests, you can
658	instead a group and set a feeder on it that generates those requests. The	1011	instead a group and set a feeder on it that generates those requests. The
659	feeder will be called whenever there are few enough (see C<feeder_limit>,	1012	feed callback will be called whenever there are few enough (see C<limit>,
660	below) requests active in the group itself and is expected to queue more	1013	below) requests active in the group itself and is expected to queue more
661	requests.	1014	requests.
662		1015
663	The feeder can queue as many requests as it likes (i.e. C<add> does not	1016	The feed callback can queue as many requests as it likes (i.e. C<add> does
664	impose any limits).	1017	not impose any limits).
665		1018
666	If the feeder does not queue more requests when called, it will be	1019	If the feed does not queue more requests when called, it will be
667	automatically removed from the group.	1020	automatically removed from the group.
668		1021
669	If the feeder limit is C<0>, it will be set to C<2> automatically.	1022	If the feed limit is C<0>, it will be set to C<2> automatically.
670		1023
671	Example:	1024	Example:
672		1025
673	# stat all files in @files, but only ever use four aio requests concurrently:	1026	# stat all files in @files, but only ever use four aio requests concurrently:
674		1027
675	my $grp = aio_group sub { print "finished\n" };	1028	my $grp = aio_group sub { print "finished\n" };
676	$grp->feeder_limit (4);	1029	limit $grp 4;
677	$grp->set_feeder (sub {	1030	feed $grp sub {
678	my $file = pop @files	1031	my $file = pop @files
679	or return;	1032	or return;
680		1033
681	add $grp aio_stat $file, sub { ... };	1034	add $grp aio_stat $file, sub { ... };
682	});	1035	};
683		1036
684	=item $grp->feeder_limit ($num)	1037	=item limit $grp $num
685		1038
686	Sets the feeder limit for the group: The feeder will be called whenever	1039	Sets the feeder limit for the group: The feeder will be called whenever
687	the group contains less than this many requests.	1040	the group contains less than this many requests.
688		1041
689	Setting the limit to C<0> will pause the feeding process.	1042	Setting the limit to C<0> will pause the feeding process.
690		1043
691	=back	1044	=back
692		1045
693	=head2 SUPPORT FUNCTIONS	1046	=head2 SUPPORT FUNCTIONS
		1047
		1048	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
694		1049
695	=over 4	1050	=over 4
696		1051
697	=item $fileno = IO::AIO::poll_fileno	1052	=item $fileno = IO::AIO::poll_fileno
698		1053
…		…
703		1058
704	See C<poll_cb> for an example.	1059	See C<poll_cb> for an example.
705		1060
706	=item IO::AIO::poll_cb	1061	=item IO::AIO::poll_cb
707		1062
708	Process all outstanding events on the result pipe. You have to call this	1063	Process some outstanding events on the result pipe. You have to call this
709	regularly. Returns the number of events processed. Returns immediately	1064	regularly. Returns the number of events processed. Returns immediately
710	when no events are outstanding.	1065	when no events are outstanding. The amount of events processed depends on
		1066	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1067
		1068	If not all requests were processed for whatever reason, the filehandle
		1069	will still be ready when C<poll_cb> returns.
711		1070
712	Example: Install an Event watcher that automatically calls	1071	Example: Install an Event watcher that automatically calls
713	IO::AIO::poll_cb with high priority:	1072	IO::AIO::poll_cb with high priority:
714		1073
715	Event->io (fd => IO::AIO::poll_fileno,	1074	Event->io (fd => IO::AIO::poll_fileno,
716	poll => 'r', async => 1,	1075	poll => 'r', async => 1,
717	cb => \&IO::AIO::poll_cb);	1076	cb => \&IO::AIO::poll_cb);
718		1077
		1078	=item IO::AIO::max_poll_reqs $nreqs
		1079
		1080	=item IO::AIO::max_poll_time $seconds
		1081
		1082	These set the maximum number of requests (default C<0>, meaning infinity)
		1083	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1084	the maximum amount of time (default C<0>, meaning infinity) spent in
		1085	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1086	of time C<poll_cb> is allowed to use).
		1087
		1088	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1089	syscall per request processed, which is not normally a problem unless your
		1090	callbacks are really really fast or your OS is really really slow (I am
		1091	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1092
		1093	Setting these is useful if you want to ensure some level of
		1094	interactiveness when perl is not fast enough to process all requests in
		1095	time.
		1096
		1097	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1098
		1099	Example: Install an Event watcher that automatically calls
		1100	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1101	program get the CPU sometimes even under high AIO load.
		1102
		1103	# try not to spend much more than 0.1s in poll_cb
		1104	IO::AIO::max_poll_time 0.1;
		1105
		1106	# use a low priority so other tasks have priority
		1107	Event->io (fd => IO::AIO::poll_fileno,
		1108	poll => 'r', nice => 1,
		1109	cb => &IO::AIO::poll_cb);
		1110
719	=item IO::AIO::poll_wait	1111	=item IO::AIO::poll_wait
720		1112
		1113	If there are any outstanding requests and none of them in the result
721	Wait till the result filehandle becomes ready for reading (simply does a	1114	phase, wait till the result filehandle becomes ready for reading (simply
722	C<select> on the filehandle. This is useful if you want to synchronously wait	1115	does a C<select> on the filehandle. This is useful if you want to
723	for some requests to finish).	1116	synchronously wait for some requests to finish).
724		1117
725	See C<nreqs> for an example.	1118	See C<nreqs> for an example.
726		1119
		1120	=item IO::AIO::poll
		1121
		1122	Waits until some requests have been handled.
		1123
		1124	Returns the number of requests processed, but is otherwise strictly
		1125	equivalent to:
		1126
		1127	IO::AIO::poll_wait, IO::AIO::poll_cb
		1128
727	=item IO::AIO::nreqs	1129	=item IO::AIO::flush
728		1130
729	Returns the number of requests currently outstanding (i.e. for which their	1131	Wait till all outstanding AIO requests have been handled.
730	callback has not been invoked yet).
731		1132
732	Example: wait till there are no outstanding requests anymore:	1133	Strictly equivalent to:
733		1134
734	IO::AIO::poll_wait, IO::AIO::poll_cb	1135	IO::AIO::poll_wait, IO::AIO::poll_cb
735	while IO::AIO::nreqs;	1136	while IO::AIO::nreqs;
736		1137
737	=item IO::AIO::flush	1138	=back
738		1139
739	Wait till all outstanding AIO requests have been handled.	1140	=head3 CONTROLLING THE NUMBER OF THREADS
740		1141
741	Strictly equivalent to:	1142	=over
742
743	IO::AIO::poll_wait, IO::AIO::poll_cb
744	while IO::AIO::nreqs;
745
746	=item IO::AIO::poll
747
748	Waits until some requests have been handled.
749
750	Strictly equivalent to:
751
752	IO::AIO::poll_wait, IO::AIO::poll_cb
753	if IO::AIO::nreqs;
754		1143
755	=item IO::AIO::min_parallel $nthreads	1144	=item IO::AIO::min_parallel $nthreads
756		1145
757	Set the minimum number of AIO threads to C<$nthreads>. The current default	1146	Set the minimum number of AIO threads to C<$nthreads>. The current
758	is C<4>, which means four asynchronous operations can be done at one time	1147	default is C<8>, which means eight asynchronous operations can execute
759	(the number of outstanding operations, however, is unlimited).	1148	concurrently at any one time (the number of outstanding requests,
		1149	however, is unlimited).
760		1150
761	IO::AIO starts threads only on demand, when an AIO request is queued and	1151	IO::AIO starts threads only on demand, when an AIO request is queued and
762	no free thread exists.	1152	no free thread exists. Please note that queueing up a hundred requests can
		1153	create demand for a hundred threads, even if it turns out that everything
		1154	is in the cache and could have been processed faster by a single thread.
763		1155
764	It is recommended to keep the number of threads low, as some Linux	1156	It is recommended to keep the number of threads relatively low, as some
765	kernel versions will scale negatively with the number of threads (higher	1157	Linux kernel versions will scale negatively with the number of threads
766	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1158	(higher parallelity => MUCH higher latency). With current Linux 2.6
767	threads should be fine.	1159	versions, 4-32 threads should be fine.
768		1160
769	Under most circumstances you don't need to call this function, as the	1161	Under most circumstances you don't need to call this function, as the
770	module selects a default that is suitable for low to moderate load.	1162	module selects a default that is suitable for low to moderate load.
771		1163
772	=item IO::AIO::max_parallel $nthreads	1164	=item IO::AIO::max_parallel $nthreads
…		…
781	This module automatically runs C<max_parallel 0> at program end, to ensure	1173	This module automatically runs C<max_parallel 0> at program end, to ensure
782	that all threads are killed and that there are no outstanding requests.	1174	that all threads are killed and that there are no outstanding requests.
783		1175
784	Under normal circumstances you don't need to call this function.	1176	Under normal circumstances you don't need to call this function.
785		1177
		1178	=item IO::AIO::max_idle $nthreads
		1179
		1180	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1181	threads that did not get a request to process within 10 seconds). That
		1182	means if a thread becomes idle while C<$nthreads> other threads are also
		1183	idle, it will free its resources and exit.
		1184
		1185	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1186	to allow for extremely high load situations, but want to free resources
		1187	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1188
		1189	The default is probably ok in most situations, especially if thread
		1190	creation is fast. If thread creation is very slow on your system you might
		1191	want to use larger values.
		1192
786	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1193	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1194
		1195	This is a very bad function to use in interactive programs because it
		1196	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1197	use an C<aio_group> together with a feed callback.
787		1198
788	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1199	Sets the maximum number of outstanding requests to C<$nreqs>. If you
789	try to queue up more than this number of requests, the caller will block until	1200	to queue up more than this number of requests, the next call to the
790	some requests have been handled.	1201	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1202	function will block until the limit is no longer exceeded.
791		1203
792	The default is very large, so normally there is no practical limit. If you	1204	The default value is very large, so there is no practical limit on the
793	queue up many requests in a loop it often improves speed if you set	1205	number of outstanding requests.
794	this to a relatively low number, such as C<100>.
795		1206
796	Under normal circumstances you don't need to call this function.	1207	You can still queue as many requests as you want. Therefore,
		1208	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1209	as a stop gap to shield against fatal memory overflow (with large values).
		1210
		1211	=back
		1212
		1213	=head3 STATISTICAL INFORMATION
		1214
		1215	=over
		1216
		1217	=item IO::AIO::nreqs
		1218
		1219	Returns the number of requests currently in the ready, execute or pending
		1220	states (i.e. for which their callback has not been invoked yet).
		1221
		1222	Example: wait till there are no outstanding requests anymore:
		1223
		1224	IO::AIO::poll_wait, IO::AIO::poll_cb
		1225	while IO::AIO::nreqs;
		1226
		1227	=item IO::AIO::nready
		1228
		1229	Returns the number of requests currently in the ready state (not yet
		1230	executed).
		1231
		1232	=item IO::AIO::npending
		1233
		1234	Returns the number of requests currently in the pending state (executed,
		1235	but not yet processed by poll_cb).
797		1236
798	=back	1237	=back
799		1238
800	=cut	1239	=cut
801		1240
…		…
813	or return undef;	1252	or return undef;
814		1253
815	*$sym	1254	*$sym
816	}	1255	}
817		1256
818	min_parallel 4;	1257	min_parallel 8;
819		1258
820	END {	1259	END { flush }
821	max_parallel 0;
822	}
823		1260
824	1;	1261	1;
825		1262
826	=head2 FORK BEHAVIOUR	1263	=head2 FORK BEHAVIOUR
827		1264
828	This module should do "the right thing" when the process using it forks:	1265	This module should do "the right thing" when the process using it forks:
829		1266
830	Before the fork, IO::AIO enters a quiescent state where no requests	1267	Before the fork, IO::AIO enters a quiescent state where no requests
831	can be added in other threads and no results will be processed. After	1268	can be added in other threads and no results will be processed. After
832	the fork the parent simply leaves the quiescent state and continues	1269	the fork the parent simply leaves the quiescent state and continues
833	request/result processing, while the child clears the request/result	1270	request/result processing, while the child frees the request/result queue
834	queue (so the requests started before the fork will only be handled in	1271	(so that the requests started before the fork will only be handled in the
835	the parent). Threads will be started on demand until the limit ste in the	1272	parent). Threads will be started on demand until the limit set in the
836	parent process has been reached again.	1273	parent process has been reached again.
837		1274
838	In short: the parent will, after a short pause, continue as if fork had	1275	In short: the parent will, after a short pause, continue as if fork had
839	not been called, while the child will act as if IO::AIO has not been used	1276	not been called, while the child will act as if IO::AIO has not been used
840	yet.	1277	yet.
841		1278
842	=head2 MEMORY USAGE	1279	=head2 MEMORY USAGE
843		1280
		1281	Per-request usage:
		1282
844	Each aio request uses - depending on your architecture - around 128 bytes	1283	Each aio request uses - depending on your architecture - around 100-200
845	of memory. In addition, stat requests need a stat buffer (possibly a few	1284	bytes of memory. In addition, stat requests need a stat buffer (possibly
846	hundred bytes). Perl scalars and other data passed into aio requests will	1285	a few hundred bytes), readdir requires a result buffer and so on. Perl
847	also be locked.	1286	scalars and other data passed into aio requests will also be locked and
		1287	will consume memory till the request has entered the done state.
848		1288
849	This is now awfully much, so queuing lots of requests is not usually a	1289	This is now awfully much, so queuing lots of requests is not usually a
850	problem.	1290	problem.
851		1291
852	Each thread needs a stack area which is usually around 16k, sometimes much	1292	Per-thread usage:
853	larger, depending on the OS.	1293
		1294	In the execution phase, some aio requests require more memory for
		1295	temporary buffers, and each thread requires a stack and other data
		1296	structures (usually around 16k-128k, depending on the OS).
		1297
		1298	=head1 KNOWN BUGS
		1299
		1300	Known bugs will be fixed in the next release.
854		1301
855	=head1 SEE ALSO	1302	=head1 SEE ALSO
856		1303
857	L<Coro>, L<Linux::AIO> (obsolete).	1304	L<Coro::AIO>.
858		1305
859	=head1 AUTHOR	1306	=head1 AUTHOR
860		1307
861	Marc Lehmann <schmorp@schmorp.de>	1308	Marc Lehmann <schmorp@schmorp.de>
862	http://home.schmorp.de/	1309	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.60 by root, Sun Oct 22 13:33:28 2006 UTC vs. Revision 1.108 by root, Fri Jun 1 13:25:50 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.60 by root, Sun Oct 22 13:33:28 2006 UTC vs.
Revision 1.108 by root, Fri Jun 1 13:25:50 2007 UTC