[ViewVC] Diff of: cvs/IO-AIO/README

Comparing IO-AIO/README (file contents):
Revision 1.36 by root, Sun Jun 7 18:31:18 2009 UTC vs.
Revision 1.46 by root, Sun Mar 27 10:26:08 2011 UTC

…		…
2	IO::AIO - Asynchronous Input/Output	2	IO::AIO - Asynchronous Input/Output
3		3
4	SYNOPSIS	4	SYNOPSIS
5	use IO::AIO;	5	use IO::AIO;
6		6
7	aio_open "/etc/passwd", O_RDONLY, 0, sub {	7	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
8	my $fh = shift	8	my $fh = shift
9	or die "/etc/passwd: $!";	9	or die "/etc/passwd: $!";
10	...	10	...
11	};	11	};
12		12
…		…
24	$req->cancel; # cancel request if still in queue	24	$req->cancel; # cancel request if still in queue
25		25
26	my $grp = aio_group sub { print "all stats done\n" };	26	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	27	add $grp aio_stat "..." for ...;
28		28
29	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30	use AnyEvent::AIO;
31
32	# EV integration
33	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
34
35	# Event integration
36	Event->io (fd => IO::AIO::poll_fileno,
37	poll => 'r',
38	cb => \&IO::AIO::poll_cb);
39
40	# Glib/Gtk2 integration
41	add_watch Glib::IO IO::AIO::poll_fileno,
42	in => sub { IO::AIO::poll_cb; 1 };
43
44	# Tk integration
45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46	readable => \&IO::AIO::poll_cb);
47
48	# Danga::Socket integration
49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50	\&IO::AIO::poll_cb);
51
52	DESCRIPTION	29	DESCRIPTION
53	This module implements asynchronous I/O using whatever means your	30	This module implements asynchronous I/O using whatever means your
54	operating system supports.	31	operating system supports. It is implemented as an interface to "libeio"
		32	(<http://software.schmorp.de/pkg/libeio.html>).
55		33
56	Asynchronous means that operations that can normally block your program	34	Asynchronous means that operations that can normally block your program
57	(e.g. reading from disk) will be done asynchronously: the operation will	35	(e.g. reading from disk) will be done asynchronously: the operation will
58	still block, but you can do something else in the meantime. This is	36	still block, but you can do something else in the meantime. This is
59	extremely useful for programs that need to stay interactive even when	37	extremely useful for programs that need to stay interactive even when
…		…
64	operations concurrently.	42	operations concurrently.
65		43
66	While most of this works on all types of file descriptors (for example	44	While most of this works on all types of file descriptors (for example
67	sockets), using these functions on file descriptors that support	45	sockets), using these functions on file descriptors that support
68	nonblocking operation (again, sockets, pipes etc.) is very inefficient.	46	nonblocking operation (again, sockets, pipes etc.) is very inefficient.
69	Use an event loop for that (such as the Event module): IO::AIO will	47	Use an event loop for that (such as the EV module): IO::AIO will
70	naturally fit into such an event loop itself.	48	naturally fit into such an event loop itself.
71		49
72	In this version, a number of threads are started that execute your	50	In this version, a number of threads are started that execute your
73	requests and signal their completion. You don't need thread support in	51	requests and signal their completion. You don't need thread support in
74	perl, and the threads created by this module will not be visible to	52	perl, and the threads created by this module will not be visible to
…		…
83	it is currently not reentrant in any way, so use appropriate locking	61	it is currently not reentrant in any way, so use appropriate locking
84	yourself, always call "poll_cb" from within the same thread, or never	62	yourself, always call "poll_cb" from within the same thread, or never
85	call "poll_cb" (or other "aio_" functions) recursively.	63	call "poll_cb" (or other "aio_" functions) recursively.
86		64
87	EXAMPLE	65	EXAMPLE
88	This is a simple example that uses the Event module and loads	66	This is a simple example that uses the EV module and loads /etc/passwd
89	/etc/passwd asynchronously:	67	asynchronously:
90		68
91	use Fcntl;	69	use Fcntl;
92	use Event;	70	use EV;
93	use IO::AIO;	71	use IO::AIO;
94		72
95	# register the IO::AIO callback with Event	73	# register the IO::AIO callback with EV
96	Event->io (fd => IO::AIO::poll_fileno,	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
97	poll => 'r',
98	cb => \&IO::AIO::poll_cb);
99		75
100	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
101	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
102	my $fh = shift	78	my $fh = shift
103	or die "error while opening: $!";	79	or die "error while opening: $!";
104		80
105	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
106	my $size = -s $fh;	82	my $size = -s $fh;
…		…
115		91
116	# file contents now in $contents	92	# file contents now in $contents
117	print $contents;	93	print $contents;
118		94
119	# exit event loop and program	95	# exit event loop and program
120	Event::unloop;	96	EV::unloop;
121	};	97	};
122	};	98	};
123		99
124	# possibly queue up other requests, or open GUI windows,	100	# possibly queue up other requests, or open GUI windows,
125	# check for sockets etc. etc.	101	# check for sockets etc. etc.
126		102
127	# process events as long as there are some:	103	# process events as long as there are some:
128	Event::loop;	104	EV::loop;
129		105
130	REQUEST ANATOMY AND LIFETIME	106	REQUEST ANATOMY AND LIFETIME
131	Every "aio_*" function creates a request. which is a C data structure	107	Every "aio_*" function creates a request. which is a C data structure
132	not directly visible to Perl.	108	not directly visible to Perl.
133		109
…		…
169	anymore (except possibly for the Perl object, but its connection to	145	anymore (except possibly for the Perl object, but its connection to
170	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
171	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
172		148
173	FUNCTIONS	149	FUNCTIONS
		150	QUICK OVERVIEW
		151	This section simply lists the prototypes of the most important functions
		152	for quick reference. See the following sections for function-by-function
		153	documentation.
		154
		155	aio_open $pathname, $flags, $mode, $callback->($fh)
		156	aio_close $fh, $callback->($status)
		157	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		158	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		159	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		160	aio_readahead $fh,$offset,$length, $callback->($retval)
		161	aio_stat $fh_or_path, $callback->($status)
		162	aio_lstat $fh, $callback->($status)
		163	aio_statvfs $fh_or_path, $callback->($statvfs)
		164	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		165	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		166	aio_truncate $fh_or_path, $offset, $callback->($status)
		167	aio_chmod $fh_or_path, $mode, $callback->($status)
		168	aio_unlink $pathname, $callback->($status)
		169	aio_mknod $path, $mode, $dev, $callback->($status)
		170	aio_link $srcpath, $dstpath, $callback->($status)
		171	aio_symlink $srcpath, $dstpath, $callback->($status)
		172	aio_readlink $path, $callback->($link)
		173	aio_rename $srcpath, $dstpath, $callback->($status)
		174	aio_mkdir $pathname, $mode, $callback->($status)
		175	aio_rmdir $pathname, $callback->($status)
		176	aio_readdir $pathname, $callback->($entries)
		177	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		178	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		179	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		180	aio_load $path, $data, $callback->($status)
		181	aio_copy $srcpath, $dstpath, $callback->($status)
		182	aio_move $srcpath, $dstpath, $callback->($status)
		183	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		184	aio_rmtree $path, $callback->($status)
		185	aio_sync $callback->($status)
		186	aio_fsync $fh, $callback->($status)
		187	aio_fdatasync $fh, $callback->($status)
		188	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		189	aio_pathsync $path, $callback->($status)
		190	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		191	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		192	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		193	aio_mlockall $flags, $callback->($status)
		194	aio_group $callback->(...)
		195	aio_nop $callback->()
		196
		197	$prev_pri = aioreq_pri [$pri]
		198	aioreq_nice $pri_adjust
		199
		200	IO::AIO::poll_wait
		201	IO::AIO::poll_cb
		202	IO::AIO::poll
		203	IO::AIO::flush
		204	IO::AIO::max_poll_reqs $nreqs
		205	IO::AIO::max_poll_time $seconds
		206	IO::AIO::min_parallel $nthreads
		207	IO::AIO::max_parallel $nthreads
		208	IO::AIO::max_idle $nthreads
		209	IO::AIO::idle_timeout $seconds
		210	IO::AIO::max_outstanding $maxreqs
		211	IO::AIO::nreqs
		212	IO::AIO::nready
		213	IO::AIO::npending
		214
		215	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		216	IO::AIO::fadvise $fh, $offset, $len, $advice
		217	IO::AIO::madvise $scalar, $offset, $length, $advice
		218	IO::AIO::mprotect $scalar, $offset, $length, $protect
		219	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		220	IO::AIO::munlockall
		221
174	AIO REQUEST FUNCTIONS	222	AIO REQUEST FUNCTIONS
175	All the "aio_*" calls are more or less thin wrappers around the syscall	223	All the "aio_*" calls are more or less thin wrappers around the syscall
176	with the same name (sans "aio_"). The arguments are similar or	224	with the same name (sans "aio_"). The arguments are similar or
177	identical, and they all accept an additional (and optional) $callback	225	identical, and they all accept an additional (and optional) $callback
178	argument which must be a code reference. This code reference will get	226	argument which must be a code reference. This code reference will get
…		…
249	will be modified by the umask in effect then the request is being	297	will be modified by the umask in effect then the request is being
250	executed, so better never change the umask.	298	executed, so better never change the umask.
251		299
252	Example:	300	Example:
253		301
254	aio_open "/etc/passwd", O_RDONLY, 0, sub {	302	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
255	if ($_[0]) {	303	if ($_[0]) {
256	print "open successful, fh is $_[0]\n";	304	print "open successful, fh is $_[0]\n";
257	...	305	...
258	} else {	306	} else {
259	die "open failed: $!\n";	307	die "open failed: $!\n";
…		…
312	reading at byte offset $in_offset, and starts writing at the current	360	reading at byte offset $in_offset, and starts writing at the current
313	file offset of $out_fh. Because of that, it is not safe to issue	361	file offset of $out_fh. Because of that, it is not safe to issue
314	more than one "aio_sendfile" per $out_fh, as they will interfere	362	more than one "aio_sendfile" per $out_fh, as they will interfere
315	with each other.	363	with each other.
316		364
		365	Please note that "aio_sendfile" can read more bytes from $in_fh than
		366	are written, and there is no way to find out how many bytes have
		367	been read from "aio_sendfile" alone, as "aio_sendfile" only provides
		368	the number of bytes written to $out_fh. Only if the result value
		369	equals $length one can assume that $length bytes have been read.
		370
		371	Unlike with other "aio_" functions, it makes a lot of sense to use
		372	"aio_sendfile" on non-blocking sockets, as long as one end
		373	(typically the $in_fh) is a file - the file I/O will then be
		374	asynchronous, while the socket I/O will be non-blocking. Note,
		375	however, that you can run into a trap where "aio_sendfile" reads
		376	some data with readahead, then fails to write all data, and when the
		377	socket is ready the next time, the data in the cache is already
		378	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		379	"aio_read" + "aio_write" let's you control resource usage much
		380	better.
		381
317	This call tries to make use of a native "sendfile" syscall to	382	This call tries to make use of a native "sendfile" syscall to
318	provide zero-copy operation. For this to work, $out_fh should refer	383	provide zero-copy operation. For this to work, $out_fh should refer
319	to a socket, and $in_fh should refer to mmap'able file.	384	to a socket, and $in_fh should refer to an mmap'able file.
320		385
321	If the native sendfile call fails or is not implemented, it will be	386	If a native sendfile cannot be found or it fails with "ENOSYS",
		387	"ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",
322	emulated, so you can call "aio_sendfile" on any type of filehandle	388	it will be emulated, so you can call "aio_sendfile" on any type of
323	regardless of the limitations of the operating system.	389	filehandle regardless of the limitations of the operating system.
324
325	Please note, however, that "aio_sendfile" can read more bytes from
326	$in_fh than are written, and there is no way to find out how many
327	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"
328	only provides the number of bytes written to $out_fh. Only if the
329	result value equals $length one can assume that $length bytes have
330	been read.
331		390
332	aio_readahead $fh,$offset,$length, $callback->($retval)	391	aio_readahead $fh,$offset,$length, $callback->($retval)
333	"aio_readahead" populates the page cache with data from a file so	392	"aio_readahead" populates the page cache with data from a file so
334	that subsequent reads from that file will not block on disk I/O. The	393	that subsequent reads from that file will not block on disk I/O. The
335	$offset argument specifies the starting point from which data is to	394	$offset argument specifies the starting point from which data is to
…		…
356	Currently, the stats are always 64-bit-stats, i.e. instead of	415	Currently, the stats are always 64-bit-stats, i.e. instead of
357	returning an error when stat'ing a large file, the results will be	416	returning an error when stat'ing a large file, the results will be
358	silently truncated unless perl itself is compiled with large file	417	silently truncated unless perl itself is compiled with large file
359	support.	418	support.
360		419
		420	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		421	the following constants and functions (if not implemented, the
		422	constants will be 0 and the functions will either "croak" or fall
		423	back on traditional behaviour).
		424
		425	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		426	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		427	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		428
361	Example: Print the length of /etc/passwd:	429	Example: Print the length of /etc/passwd:
362		430
363	aio_stat "/etc/passwd", sub {	431	aio_stat "/etc/passwd", sub {
364	$_[0] and die "stat failed: $!";	432	$_[0] and die "stat failed: $!";
365	print "size is ", -s _, "\n";	433	print "size is ", -s _, "\n";
366	};	434	};
367		435
		436	aio_statvfs $fh_or_path, $callback->($statvfs)
		437	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		438	whether a file handle or path was passed.
		439
		440	On success, the callback is passed a hash reference with the
		441	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		442	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		443	failure, "undef" is passed.
		444
		445	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		446	and "ST_NOSUID".
		447
		448	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		449	their correct value when available, or to 0 on systems that do not
		450	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		451	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		452	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		453
		454	Example: stat "/wd" and dump out the data if successful.
		455
		456	aio_statvfs "/wd", sub {
		457	my $f = $_[0]
		458	or die "statvfs: $!";
		459
		460	use Data::Dumper;
		461	say Dumper $f;
		462	};
		463
		464	# result:
		465	{
		466	bsize => 1024,
		467	bfree => 4333064312,
		468	blocks => 10253828096,
		469	files => 2050765568,
		470	flag => 4096,
		471	favail => 2042092649,
		472	bavail => 4333064312,
		473	ffree => 2042092649,
		474	namemax => 255,
		475	frsize => 1024,
		476	fsid => 1810
		477	}
		478
368	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	479	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
369	Works like perl's "utime" function (including the special case of	480	Works like perl's "utime" function (including the special case of
370	$atime and $mtime being undef). Fractional times are supported if	481	$atime and $mtime being undef). Fractional times are supported if
371	the underlying syscalls support them.	482	the underlying syscalls support them.
372		483
…		…
409	Asynchronously create a device node (or fifo). See mknod(2).	520	Asynchronously create a device node (or fifo). See mknod(2).
410		521
411	The only (POSIX-) portable way of calling this function is:	522	The only (POSIX-) portable way of calling this function is:
412		523
413	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	524	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		525
		526	See "aio_stat" for info about some potentially helpful extra
		527	constants and functions.
414		528
415	aio_link $srcpath, $dstpath, $callback->($status)	529	aio_link $srcpath, $dstpath, $callback->($status)
416	Asynchronously create a new link to the existing object at $srcpath	530	Asynchronously create a new link to the existing object at $srcpath
417	at the path $dstpath and call the callback with the result code.	531	at the path $dstpath and call the callback with the result code.
418		532
…		…
474	you need to know, you have to run stat yourself. Also, for speed	588	you need to know, you have to run stat yourself. Also, for speed
475	reasons, the $type scalars are read-only: you can not modify	589	reasons, the $type scalars are read-only: you can not modify
476	them.	590	them.
477		591
478	$inode is the inode number (which might not be exact on systems	592	$inode is the inode number (which might not be exact on systems
479	with 64 bit inode numbers and 32 bit perls). On systems that do	593	with 64 bit inode numbers and 32 bit perls). This field has
480	not deliver the inode information, this will always be zero.	594	unspecified content on systems that do not deliver the inode
		595	information.
481		596
482	IO::AIO::READDIR_DIRS_FIRST	597	IO::AIO::READDIR_DIRS_FIRST
483	When this flag is set, then the names will be returned in an	598	When this flag is set, then the names will be returned in an
484	order where likely directories come first. This is useful when	599	order where likely directories come first. This is useful when
485	you need to quickly find directories, or you want to find all	600	you need to quickly find directories, or you want to find all
…		…
512	into memory. Status is the same as with aio_read.	627	into memory. Status is the same as with aio_read.
513		628
514	aio_copy $srcpath, $dstpath, $callback->($status)	629	aio_copy $srcpath, $dstpath, $callback->($status)
515	Try to copy the file (directories not supported as either source	630	Try to copy the file (directories not supported as either source
516	or destination) from $srcpath to $dstpath and call the callback with	631	or destination) from $srcpath to $dstpath and call the callback with
517	the 0 (error) or -1 ok.	632	a status of 0 (ok) or -1 (error, see $!).
518		633
519	This is a composite request that creates the destination file with	634	This is a composite request that creates the destination file with
520	mode 0200 and copies the contents of the source file into it using	635	mode 0200 and copies the contents of the source file into it using
521	"aio_sendfile", followed by restoring atime, mtime, access mode and	636	"aio_sendfile", followed by restoring atime, mtime, access mode and
522	uid/gid, in that order.	637	uid/gid, in that order.
…		…
526	uid/gid, where errors are being ignored.	641	uid/gid, where errors are being ignored.
527		642
528	aio_move $srcpath, $dstpath, $callback->($status)	643	aio_move $srcpath, $dstpath, $callback->($status)
529	Try to move the file (directories not supported as either source	644	Try to move the file (directories not supported as either source
530	or destination) from $srcpath to $dstpath and call the callback with	645	or destination) from $srcpath to $dstpath and call the callback with
531	the 0 (error) or -1 ok.	646	a status of 0 (ok) or -1 (error, see $!).
532		647
533	This is a composite request that tries to rename(2) the file first;	648	This is a composite request that tries to rename(2) the file first;
534	if rename fails with "EXDEV", it copies the file with "aio_copy"	649	if rename fails with "EXDEV", it copies the file with "aio_copy"
535	and, if that is successful, unlinks the $srcpath.	650	and, if that is successful, unlinks the $srcpath.
536		651
…		…
631	operations (E.g. rename). This might not work on all operating	746	operations (E.g. rename). This might not work on all operating
632	systems or have any specific effect, but usually it makes sure that	747	systems or have any specific effect, but usually it makes sure that
633	directory changes get written to disc. It works for anything that	748	directory changes get written to disc. It works for anything that
634	can be opened for read-only, not just directories.	749	can be opened for read-only, not just directories.
635		750
		751	Future versions of this function might fall back to other methods
		752	when "fsync" on the directory fails (such as calling "sync").
		753
636	Passes 0 when everything went ok, and -1 on error.	754	Passes 0 when everything went ok, and -1 on error.
		755
		756	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		757	$callback->($status)
		758	This is a rather advanced IO::AIO call, which only works on
		759	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		760	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		761	note that the scalar must only be modified in-place while an aio
		762	operation is pending on it).
		763
		764	It calls the "msync" function of your OS, if available, with the
		765	memory area starting at $offset in the string and ending $length
		766	bytes later. If $length is negative, counts from the end, and if
		767	$length is "undef", then it goes till the end of the string. The
		768	flags can be a combination of "IO::AIO::MS_ASYNC",
		769	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		770
		771	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		772	$callback->($status)
		773	This is a rather advanced IO::AIO call, which works best on
		774	mmap(2)ed scalars.
		775
		776	It touches (reads or writes) all memory pages in the specified range
		777	inside the scalar. All caveats and parameters are the same as for
		778	"aio_msync", above, except for flags, which must be either 0 (which
		779	reads all pages and ensures they are instantiated) or
		780	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		781	and writing an octet from it, which dirties the page).
		782
		783	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		784	This is a rather advanced IO::AIO call, which works best on
		785	mmap(2)ed scalars.
		786
		787	It reads in all the pages of the underlying storage into memory (if
		788	any) and locks them, so they are not getting swapped/paged out or
		789	removed.
		790
		791	If $length is undefined, then the scalar will be locked till the
		792	end.
		793
		794	On systems that do not implement "mlock", this function returns -1
		795	and sets errno to "ENOSYS".
		796
		797	Note that the corresponding "munlock" is synchronous and is
		798	documented under "MISCELLANEOUS FUNCTIONS".
		799
		800	Example: open a file, mmap and mlock it - both will be undone when
		801	$data gets destroyed.
		802
		803	open my $fh, "<", $path or die "$path: $!";
		804	my $data;
		805	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		806	aio_mlock $data; # mlock in background
		807
		808	aio_mlockall $flags, $callback->($status)
		809	Calls the "mlockall" function with the given $flags (a combination
		810	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		811
		812	On systems that do not implement "mlockall", this function returns
		813	-1 and sets errno to "ENOSYS".
		814
		815	Note that the corresponding "munlockall" is synchronous and is
		816	documented under "MISCELLANEOUS FUNCTIONS".
		817
		818	Example: asynchronously lock all current and future pages into
		819	memory.
		820
		821	aio_mlockall IO::AIO::MCL_FUTURE;
637		822
638	aio_group $callback->(...)	823	aio_group $callback->(...)
639	This is a very special aio request: Instead of doing something, it	824	This is a very special aio request: Instead of doing something, it
640	is a container for other aio requests, which is useful if you want	825	is a container for other aio requests, which is useful if you want
641	to bundle many requests into a single, composite, request with a	826	to bundle many requests into a single, composite, request with a
…		…
684		869
685	cancel $req	870	cancel $req
686	Cancels the request, if possible. Has the effect of skipping	871	Cancels the request, if possible. Has the effect of skipping
687	execution when entering the execute state and skipping calling the	872	execution when entering the execute state and skipping calling the
688	callback when entering the the result state, but will leave the	873	callback when entering the the result state, but will leave the
689	request otherwise untouched. That means that requests that currently	874	request otherwise untouched (with the exception of readdir). That
690	execute will not be stopped and resources held by the request will	875	means that requests that currently execute will not be stopped and
691	not be freed prematurely.	876	resources held by the request will not be freed prematurely.
692		877
693	cb $req $callback->(...)	878	cb $req $callback->(...)
694	Replace (or simply set) the callback registered to the request.	879	Replace (or simply set) the callback registered to the request.
695		880
696	IO::AIO::GRP CLASS	881	IO::AIO::GRP CLASS
…		…
757		942
758	$grp->cancel_subs	943	$grp->cancel_subs
759	Cancel all subrequests and clears any feeder, but not the group	944	Cancel all subrequests and clears any feeder, but not the group
760	request itself. Useful when you queued a lot of events but got a	945	request itself. Useful when you queued a lot of events but got a
761	result early.	946	result early.
		947
		948	The group request will finish normally (you cannot add requests to
		949	the group).
762		950
763	$grp->result (...)	951	$grp->result (...)
764	Set the result value(s) that will be passed to the group callback	952	Set the result value(s) that will be passed to the group callback
765	when all subrequests have finished and set the groups errno to the	953	when all subrequests have finished and set the groups errno to the
766	current value of errno (just like calling "errno" without an error	954	current value of errno (just like calling "errno" without an error
…		…
826	SUPPORT FUNCTIONS	1014	SUPPORT FUNCTIONS
827	EVENT PROCESSING AND EVENT LOOP INTEGRATION	1015	EVENT PROCESSING AND EVENT LOOP INTEGRATION
828	$fileno = IO::AIO::poll_fileno	1016	$fileno = IO::AIO::poll_fileno
829	Return the request result pipe file descriptor. This filehandle	1017	Return the request result pipe file descriptor. This filehandle
830	must be polled for reading by some mechanism outside this module	1018	must be polled for reading by some mechanism outside this module
831	(e.g. Event or select, see below or the SYNOPSIS). If the pipe	1019	(e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
832	becomes readable you have to call "poll_cb" to check the results.	1020	pipe becomes readable you have to call "poll_cb" to check the
		1021	results.
833		1022
834	See "poll_cb" for an example.	1023	See "poll_cb" for an example.
835		1024
836	IO::AIO::poll_cb	1025	IO::AIO::poll_cb
837	Process some outstanding events on the result pipe. You have to call	1026	Process some outstanding events on the result pipe. You have to call
…		…
844	If not all requests were processed for whatever reason, the	1033	If not all requests were processed for whatever reason, the
845	filehandle will still be ready when "poll_cb" returns, so normally	1034	filehandle will still be ready when "poll_cb" returns, so normally
846	you don't have to do anything special to have it called later.	1035	you don't have to do anything special to have it called later.
847		1036
848	Example: Install an Event watcher that automatically calls	1037	Example: Install an Event watcher that automatically calls
849	IO::AIO::poll_cb with high priority:	1038	IO::AIO::poll_cb with high priority (more examples can be found in
		1039	the SYNOPSIS section, at the top of this document):
850		1040
851	Event->io (fd => IO::AIO::poll_fileno,	1041	Event->io (fd => IO::AIO::poll_fileno,
852	poll => 'r', async => 1,	1042	poll => 'r', async => 1,
853	cb => \&IO::AIO::poll_cb);	1043	cb => \&IO::AIO::poll_cb);
		1044
		1045	IO::AIO::poll_wait
		1046	If there are any outstanding requests and none of them in the result
		1047	phase, wait till the result filehandle becomes ready for reading
		1048	(simply does a "select" on the filehandle. This is useful if you
		1049	want to synchronously wait for some requests to finish).
		1050
		1051	See "nreqs" for an example.
		1052
		1053	IO::AIO::poll
		1054	Waits until some requests have been handled.
		1055
		1056	Returns the number of requests processed, but is otherwise strictly
		1057	equivalent to:
		1058
		1059	IO::AIO::poll_wait, IO::AIO::poll_cb
		1060
		1061	IO::AIO::flush
		1062	Wait till all outstanding AIO requests have been handled.
		1063
		1064	Strictly equivalent to:
		1065
		1066	IO::AIO::poll_wait, IO::AIO::poll_cb
		1067	while IO::AIO::nreqs;
854		1068
855	IO::AIO::max_poll_reqs $nreqs	1069	IO::AIO::max_poll_reqs $nreqs
856	IO::AIO::max_poll_time $seconds	1070	IO::AIO::max_poll_time $seconds
857	These set the maximum number of requests (default 0, meaning	1071	These set the maximum number of requests (default 0, meaning
858	infinity) that are being processed by "IO::AIO::poll_cb" in one	1072	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
882	# use a low priority so other tasks have priority	1096	# use a low priority so other tasks have priority
883	Event->io (fd => IO::AIO::poll_fileno,	1097	Event->io (fd => IO::AIO::poll_fileno,
884	poll => 'r', nice => 1,	1098	poll => 'r', nice => 1,
885	cb => &IO::AIO::poll_cb);	1099	cb => &IO::AIO::poll_cb);
886		1100
887	IO::AIO::poll_wait
888	If there are any outstanding requests and none of them in the result
889	phase, wait till the result filehandle becomes ready for reading
890	(simply does a "select" on the filehandle. This is useful if you
891	want to synchronously wait for some requests to finish).
892
893	See "nreqs" for an example.
894
895	IO::AIO::poll
896	Waits until some requests have been handled.
897
898	Returns the number of requests processed, but is otherwise strictly
899	equivalent to:
900
901	IO::AIO::poll_wait, IO::AIO::poll_cb
902
903	IO::AIO::flush
904	Wait till all outstanding AIO requests have been handled.
905
906	Strictly equivalent to:
907
908	IO::AIO::poll_wait, IO::AIO::poll_cb
909	while IO::AIO::nreqs;
910
911	CONTROLLING THE NUMBER OF THREADS	1101	CONTROLLING THE NUMBER OF THREADS
912	IO::AIO::min_parallel $nthreads	1102	IO::AIO::min_parallel $nthreads
913	Set the minimum number of AIO threads to $nthreads. The current	1103	Set the minimum number of AIO threads to $nthreads. The current
914	default is 8, which means eight asynchronous operations can execute	1104	default is 8, which means eight asynchronous operations can execute
915	concurrently at any one time (the number of outstanding requests,	1105	concurrently at any one time (the number of outstanding requests,
…		…
944		1134
945	Under normal circumstances you don't need to call this function.	1135	Under normal circumstances you don't need to call this function.
946		1136
947	IO::AIO::max_idle $nthreads	1137	IO::AIO::max_idle $nthreads
948	Limit the number of threads (default: 4) that are allowed to idle	1138	Limit the number of threads (default: 4) that are allowed to idle
949	(i.e., threads that did not get a request to process within 10	1139	(i.e., threads that did not get a request to process within the idle
950	seconds). That means if a thread becomes idle while $nthreads other	1140	timeout (default: 10 seconds). That means if a thread becomes idle
951	threads are also idle, it will free its resources and exit.	1141	while $nthreads other threads are also idle, it will free its
		1142	resources and exit.
952		1143
953	This is useful when you allow a large number of threads (e.g. 100 or	1144	This is useful when you allow a large number of threads (e.g. 100 or
954	1000) to allow for extremely high load situations, but want to free	1145	1000) to allow for extremely high load situations, but want to free
955	resources under normal circumstances (1000 threads can easily	1146	resources under normal circumstances (1000 threads can easily
956	consume 30MB of RAM).	1147	consume 30MB of RAM).
957		1148
958	The default is probably ok in most situations, especially if thread	1149	The default is probably ok in most situations, especially if thread
959	creation is fast. If thread creation is very slow on your system you	1150	creation is fast. If thread creation is very slow on your system you
960	might want to use larger values.	1151	might want to use larger values.
		1152
		1153	IO::AIO::idle_timeout $seconds
		1154	Sets the minimum idle timeout (default 10) after which worker
		1155	threads are allowed to exit. SEe "IO::AIO::max_idle".
961		1156
962	IO::AIO::max_outstanding $maxreqs	1157	IO::AIO::max_outstanding $maxreqs
963	This is a very bad function to use in interactive programs because	1158	This is a very bad function to use in interactive programs because
964	it blocks, and a bad way to reduce concurrency because it is	1159	it blocks, and a bad way to reduce concurrency because it is
965	inexact: Better use an "aio_group" together with a feed callback.	1160	inexact: Better use an "aio_group" together with a feed callback.
…		…
993	executed).	1188	executed).
994		1189
995	IO::AIO::npending	1190	IO::AIO::npending
996	Returns the number of requests currently in the pending state	1191	Returns the number of requests currently in the pending state
997	(executed, but not yet processed by poll_cb).	1192	(executed, but not yet processed by poll_cb).
		1193
		1194	MISCELLANEOUS FUNCTIONS
		1195	IO::AIO implements some functions that might be useful, but are not
		1196	asynchronous.
		1197
		1198	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1199	Calls the "eio_sendfile_sync" function, which is like
		1200	"aio_sendfile", but is blocking (this makes most sense if you know
		1201	the input data is likely cached already and the output filehandle is
		1202	set to non-blocking operations).
		1203
		1204	Returns the number of bytes copied, or -1 on error.
		1205
		1206	IO::AIO::fadvise $fh, $offset, $len, $advice
		1207	Simply calls the "posix_fadvise" function (see its manpage for
		1208	details). The following advice constants are avaiable:
		1209	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1210	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1211	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1212
		1213	On systems that do not implement "posix_fadvise", this function
		1214	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1215
		1216	IO::AIO::madvise $scalar, $offset, $len, $advice
		1217	Simply calls the "posix_madvise" function (see its manpage for
		1218	details). The following advice constants are avaiable:
		1219	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1220	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1221	"IO::AIO::MADV_DONTNEED".
		1222
		1223	On systems that do not implement "posix_madvise", this function
		1224	returns ENOSYS, otherwise the return value of "posix_madvise".
		1225
		1226	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1227	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1228	$scalar (see its manpage for details). The following protect
		1229	constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1230	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1231
		1232	On systems that do not implement "mprotect", this function returns
		1233	ENOSYS, otherwise the return value of "mprotect".
		1234
		1235	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1236	Memory-maps a file (or anonymous memory range) and attaches it to
		1237	the given $scalar, which will act like a string scalar.
		1238
		1239	The only operations allowed on the scalar are "substr"/"vec" that
		1240	don't change the string length, and most read-only operations such
		1241	as copying it or searching it with regexes and so on.
		1242
		1243	Anything else is unsafe and will, at best, result in memory leaks.
		1244
		1245	The memory map associated with the $scalar is automatically removed
		1246	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1247	"IO::AIO::munmap" functions are called.
		1248
		1249	This calls the "mmap"(2) function internally. See your system's
		1250	manual page for details on the $length, $prot and $flags parameters.
		1251
		1252	The $length must be larger than zero and smaller than the actual
		1253	filesize.
		1254
		1255	$prot is a combination of "IO::AIO::PROT_NONE",
		1256	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1257	"IO::AIO::PROT_WRITE",
		1258
		1259	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1260	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1261	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1262	(which is set to "MAP_ANON" if your system only provides this
		1263	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1264	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1265	"IO::AIO::MAP_NONBLOCK"
		1266
		1267	If $fh is "undef", then a file descriptor of -1 is passed.
		1268
		1269	$offset is the offset from the start of the file - it generally must
		1270	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1271
		1272	Example:
		1273
		1274	use Digest::MD5;
		1275	use IO::AIO;
		1276
		1277	open my $fh, "<verybigfile"
		1278	or die "$!";
		1279
		1280	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1281	or die "verybigfile: $!";
		1282
		1283	my $fast_md5 = md5 $data;
		1284
		1285	IO::AIO::munmap $scalar
		1286	Removes a previous mmap and undefines the $scalar.
		1287
		1288	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1289	Calls the "munlock" function, undoing the effects of a previous
		1290	"aio_mlock" call (see its description for details).
		1291
		1292	IO::AIO::munlockall
		1293	Calls the "munlockall" function.
		1294
		1295	On systems that do not implement "munlockall", this function returns
		1296	ENOSYS, otherwise the return value of "munlockall".
		1297
		1298	EVENT LOOP INTEGRATION
		1299	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1300	automatically into many event loops:
		1301
		1302	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1303	use AnyEvent::AIO;
		1304
		1305	You can also integrate IO::AIO manually into many event loops, here are
		1306	some examples of how to do this:
		1307
		1308	# EV integration
		1309	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1310
		1311	# Event integration
		1312	Event->io (fd => IO::AIO::poll_fileno,
		1313	poll => 'r',
		1314	cb => \&IO::AIO::poll_cb);
		1315
		1316	# Glib/Gtk2 integration
		1317	add_watch Glib::IO IO::AIO::poll_fileno,
		1318	in => sub { IO::AIO::poll_cb; 1 };
		1319
		1320	# Tk integration
		1321	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1322	readable => \&IO::AIO::poll_cb);
		1323
		1324	# Danga::Socket integration
		1325	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1326	\&IO::AIO::poll_cb);
998		1327
999	FORK BEHAVIOUR	1328	FORK BEHAVIOUR
1000	This module should do "the right thing" when the process using it forks:	1329	This module should do "the right thing" when the process using it forks:
1001		1330
1002	Before the fork, IO::AIO enters a quiescent state where no requests can	1331	Before the fork, IO::AIO enters a quiescent state where no requests can

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Comparing IO-AIO/README (file contents): Revision 1.36 by root, Sun Jun 7 18:31:18 2009 UTC vs. Revision 1.46 by root, Sun Mar 27 10:26:08 2011 UTC

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Comparing IO-AIO/README (file contents):
Revision 1.36 by root, Sun Jun 7 18:31:18 2009 UTC vs.
Revision 1.46 by root, Sun Mar 27 10:26:08 2011 UTC