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

Comparing IO-AIO/README (file contents):
Revision 1.39 by root, Wed Aug 5 11:53:16 2009 UTC vs.
Revision 1.48 by root, Wed Jun 29 11:25:17 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
…		…
23	my $req = aio_unlink "/tmp/file", sub { };	23	my $req = aio_unlink "/tmp/file", sub { };
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
29	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30	use AnyEvent::AIO;
31
32	# EV integration
33	my $aio_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		28
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. It is implemented as an interface to "libeio"	31	operating system supports. It is implemented as an interface to "libeio"
55	(<http://software.schmorp.de/pkg/libeio.html>).	32	(<http://software.schmorp.de/pkg/libeio.html>).
…		…
95		72
96	# register the IO::AIO callback with EV	73	# register the IO::AIO callback with EV
97	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98		75
99	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
100	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
101	my $fh = shift	78	my $fh = shift
102	or die "error while opening: $!";	79	or die "error while opening: $!";
103		80
104	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
105	my $size = -s $fh;	82	my $size = -s $fh;
…		…
168	anymore (except possibly for the Perl object, but its connection to	145	anymore (except possibly for the Perl object, but its connection to
169	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
170	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
171		148
172	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
173	AIO REQUEST FUNCTIONS	222	AIO REQUEST FUNCTIONS
174	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
175	with the same name (sans "aio_"). The arguments are similar or	224	with the same name (sans "aio_"). The arguments are similar or
176	identical, and they all accept an additional (and optional) $callback	225	identical, and they all accept an additional (and optional) $callback
177	argument which must be a code reference. This code reference will get	226	argument which must be a code reference. This code reference will get
…		…
248	will be modified by the umask in effect then the request is being	297	will be modified by the umask in effect then the request is being
249	executed, so better never change the umask.	298	executed, so better never change the umask.
250		299
251	Example:	300	Example:
252		301
253	aio_open "/etc/passwd", O_RDONLY, 0, sub {	302	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
254	if ($_[0]) {	303	if ($_[0]) {
255	print "open successful, fh is $_[0]\n";	304	print "open successful, fh is $_[0]\n";
256	...	305	...
257	} else {	306	} else {
258	die "open failed: $!\n";	307	die "open failed: $!\n";
259	}	308	}
260	};	309	};
261		310
		311	In addition to all the common open modes/flags ("O_RDONLY",
		312	"O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
		313	"O_APPEND"), the following POSIX and non-POSIX constants are
		314	available (missing ones on your system are, as usual, 0):
		315
		316	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
		317	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
		318	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
		319
262	aio_close $fh, $callback->($status)	320	aio_close $fh, $callback->($status)
263	Asynchronously close a file and call the callback with the result	321	Asynchronously close a file and call the callback with the result
264	code.	322	code.
265		323
266	Unfortunately, you can't do this to perl. Perl insists very	324	Unfortunately, you can't do this to perl. Perl insists very
…		…
309	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	367	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
310	Tries to copy $length bytes from $in_fh to $out_fh. It starts	368	Tries to copy $length bytes from $in_fh to $out_fh. It starts
311	reading at byte offset $in_offset, and starts writing at the current	369	reading at byte offset $in_offset, and starts writing at the current
312	file offset of $out_fh. Because of that, it is not safe to issue	370	file offset of $out_fh. Because of that, it is not safe to issue
313	more than one "aio_sendfile" per $out_fh, as they will interfere	371	more than one "aio_sendfile" per $out_fh, as they will interfere
314	with each other.	372	with each other. The same $in_fh works fine though, as this function
		373	does not move or use the file offset of $in_fh.
315		374
		375	Please note that "aio_sendfile" can read more bytes from $in_fh than
		376	are written, and there is no way to find out how many more bytes
		377	have been read from "aio_sendfile" alone, as "aio_sendfile" only
		378	provides the number of bytes written to $out_fh. Only if the result
		379	value equals $length one can assume that $length bytes have been
		380	read.
		381
		382	Unlike with other "aio_" functions, it makes a lot of sense to use
		383	"aio_sendfile" on non-blocking sockets, as long as one end
		384	(typically the $in_fh) is a file - the file I/O will then be
		385	asynchronous, while the socket I/O will be non-blocking. Note,
		386	however, that you can run into a trap where "aio_sendfile" reads
		387	some data with readahead, then fails to write all data, and when the
		388	socket is ready the next time, the data in the cache is already
		389	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		390	"aio_read" + "aio_write" let's you better control resource usage.
		391
316	This call tries to make use of a native "sendfile" syscall to	392	This call tries to make use of a native "sendfile"-like syscall to
317	provide zero-copy operation. For this to work, $out_fh should refer	393	provide zero-copy operation. For this to work, $out_fh should refer
318	to a socket, and $in_fh should refer to mmap'able file.	394	to a socket, and $in_fh should refer to an mmap'able file.
319		395
320	If the native sendfile call fails or is not implemented, it will be	396	If a native sendfile cannot be found or it fails with "ENOSYS",
321	emulated, so you can call "aio_sendfile" on any type of filehandle	397	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
322	regardless of the limitations of the operating system.	398	"ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
		399	any type of filehandle regardless of the limitations of the
		400	operating system.
323		401
324	Please note, however, that "aio_sendfile" can read more bytes from	402	As native sendfile syscalls (as practically any non-POSIX interface
325	$in_fh than are written, and there is no way to find out how many	403	hacked together in a hurry to improve benchmark numbers) tend to be
326	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	404	rather buggy on many systems, this implementation tries to work
327	only provides the number of bytes written to $out_fh. Only if the	405	around some known bugs in Linux and FreeBSD kernels (probably
328	result value equals $length one can assume that $length bytes have	406	others, too), but that might fail, so you really really should check
329	been read.	407	the return value of "aio_sendfile" - fewre bytes than expected might
		408	have been transferred.
330		409
331	aio_readahead $fh,$offset,$length, $callback->($retval)	410	aio_readahead $fh,$offset,$length, $callback->($retval)
332	"aio_readahead" populates the page cache with data from a file so	411	"aio_readahead" populates the page cache with data from a file so
333	that subsequent reads from that file will not block on disk I/O. The	412	that subsequent reads from that file will not block on disk I/O. The
334	$offset argument specifies the starting point from which data is to	413	$offset argument specifies the starting point from which data is to
…		…
355	Currently, the stats are always 64-bit-stats, i.e. instead of	434	Currently, the stats are always 64-bit-stats, i.e. instead of
356	returning an error when stat'ing a large file, the results will be	435	returning an error when stat'ing a large file, the results will be
357	silently truncated unless perl itself is compiled with large file	436	silently truncated unless perl itself is compiled with large file
358	support.	437	support.
359		438
		439	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		440	the following constants and functions (if not implemented, the
		441	constants will be 0 and the functions will either "croak" or fall
		442	back on traditional behaviour).
		443
		444	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		445	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		446	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		447
360	Example: Print the length of /etc/passwd:	448	Example: Print the length of /etc/passwd:
361		449
362	aio_stat "/etc/passwd", sub {	450	aio_stat "/etc/passwd", sub {
363	$_[0] and die "stat failed: $!";	451	$_[0] and die "stat failed: $!";
364	print "size is ", -s _, "\n";	452	print "size is ", -s _, "\n";
365	};	453	};
366		454
		455	aio_statvfs $fh_or_path, $callback->($statvfs)
		456	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		457	whether a file handle or path was passed.
		458
		459	On success, the callback is passed a hash reference with the
		460	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		461	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		462	failure, "undef" is passed.
		463
		464	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		465	and "ST_NOSUID".
		466
		467	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		468	their correct value when available, or to 0 on systems that do not
		469	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		470	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		471	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		472
		473	Example: stat "/wd" and dump out the data if successful.
		474
		475	aio_statvfs "/wd", sub {
		476	my $f = $_[0]
		477	or die "statvfs: $!";
		478
		479	use Data::Dumper;
		480	say Dumper $f;
		481	};
		482
		483	# result:
		484	{
		485	bsize => 1024,
		486	bfree => 4333064312,
		487	blocks => 10253828096,
		488	files => 2050765568,
		489	flag => 4096,
		490	favail => 2042092649,
		491	bavail => 4333064312,
		492	ffree => 2042092649,
		493	namemax => 255,
		494	frsize => 1024,
		495	fsid => 1810
		496	}
		497
367	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	498	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
368	Works like perl's "utime" function (including the special case of	499	Works like perl's "utime" function (including the special case of
369	$atime and $mtime being undef). Fractional times are supported if	500	$atime and $mtime being undef). Fractional times are supported if
370	the underlying syscalls support them.	501	the underlying syscalls support them.
371		502
…		…
409		540
410	The only (POSIX-) portable way of calling this function is:	541	The only (POSIX-) portable way of calling this function is:
411		542
412	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	543	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
413		544
		545	See "aio_stat" for info about some potentially helpful extra
		546	constants and functions.
		547
414	aio_link $srcpath, $dstpath, $callback->($status)	548	aio_link $srcpath, $dstpath, $callback->($status)
415	Asynchronously create a new link to the existing object at $srcpath	549	Asynchronously create a new link to the existing object at $srcpath
416	at the path $dstpath and call the callback with the result code.	550	at the path $dstpath and call the callback with the result code.
417		551
418	aio_symlink $srcpath, $dstpath, $callback->($status)	552	aio_symlink $srcpath, $dstpath, $callback->($status)
…		…
454	The flags are a combination of the following constants, ORed	588	The flags are a combination of the following constants, ORed
455	together (the flags will also be passed to the callback, possibly	589	together (the flags will also be passed to the callback, possibly
456	modified):	590	modified):
457		591
458	IO::AIO::READDIR_DENTS	592	IO::AIO::READDIR_DENTS
459	When this flag is off, then the callback gets an arrayref with	593	When this flag is off, then the callback gets an arrayref
460	of names only (as with "aio_readdir"), otherwise it gets an	594	consisting of names only (as with "aio_readdir"), otherwise it
461	arrayref with "[$name, $type, $inode]" arrayrefs, each	595	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
462	describing a single directory entry in more detail.	596	describing a single directory entry in more detail.
463		597
464	$name is the name of the entry.	598	$name is the name of the entry.
465		599
466	$type is one of the "IO::AIO::DT_xxx" constants:	600	$type is one of the "IO::AIO::DT_xxx" constants:
…		…
479	unspecified content on systems that do not deliver the inode	613	unspecified content on systems that do not deliver the inode
480	information.	614	information.
481		615
482	IO::AIO::READDIR_DIRS_FIRST	616	IO::AIO::READDIR_DIRS_FIRST
483	When this flag is set, then the names will be returned in an	617	When this flag is set, then the names will be returned in an
484	order where likely directories come first. This is useful when	618	order where likely directories come first, in optimal stat
485	you need to quickly find directories, or you want to find all	619	order. This is useful when you need to quickly find directories,
486	directories while avoiding to stat() each entry.	620	or you want to find all directories while avoiding to stat()
		621	each entry.
487		622
488	If the system returns type information in readdir, then this is	623	If the system returns type information in readdir, then this is
489	used to find directories directly. Otherwise, likely directories	624	used to find directories directly. Otherwise, likely directories
490	are files beginning with ".", or otherwise files with no dots,	625	are names beginning with ".", or otherwise names with no dots,
491	of which files with short names are tried first.	626	of which names with short names are tried first.
492		627
493	IO::AIO::READDIR_STAT_ORDER	628	IO::AIO::READDIR_STAT_ORDER
494	When this flag is set, then the names will be returned in an	629	When this flag is set, then the names will be returned in an
495	order suitable for stat()'ing each one. That is, when you plan	630	order suitable for stat()'ing each one. That is, when you plan
496	to stat() all files in the given directory, then the returned	631	to stat() all files in the given directory, then the returned
…		…
512	into memory. Status is the same as with aio_read.	647	into memory. Status is the same as with aio_read.
513		648
514	aio_copy $srcpath, $dstpath, $callback->($status)	649	aio_copy $srcpath, $dstpath, $callback->($status)
515	Try to copy the file (directories not supported as either source	650	Try to copy the file (directories not supported as either source
516	or destination) from $srcpath to $dstpath and call the callback with	651	or destination) from $srcpath to $dstpath and call the callback with
517	the 0 (error) or -1 ok.	652	a status of 0 (ok) or -1 (error, see $!).
518		653
519	This is a composite request that creates the destination file with	654	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	655	mode 0200 and copies the contents of the source file into it using
521	"aio_sendfile", followed by restoring atime, mtime, access mode and	656	"aio_sendfile", followed by restoring atime, mtime, access mode and
522	uid/gid, in that order.	657	uid/gid, in that order.
…		…
526	uid/gid, where errors are being ignored.	661	uid/gid, where errors are being ignored.
527		662
528	aio_move $srcpath, $dstpath, $callback->($status)	663	aio_move $srcpath, $dstpath, $callback->($status)
529	Try to move the file (directories not supported as either source	664	Try to move the file (directories not supported as either source
530	or destination) from $srcpath to $dstpath and call the callback with	665	or destination) from $srcpath to $dstpath and call the callback with
531	the 0 (error) or -1 ok.	666	a status of 0 (ok) or -1 (error, see $!).
532		667
533	This is a composite request that tries to rename(2) the file first;	668	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"	669	if rename fails with "EXDEV", it copies the file with "aio_copy"
535	and, if that is successful, unlinks the $srcpath.	670	and, if that is successful, unlinks the $srcpath.
536		671
…		…
636	Future versions of this function might fall back to other methods	771	Future versions of this function might fall back to other methods
637	when "fsync" on the directory fails (such as calling "sync").	772	when "fsync" on the directory fails (such as calling "sync").
638		773
639	Passes 0 when everything went ok, and -1 on error.	774	Passes 0 when everything went ok, and -1 on error.
640		775
		776	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		777	$callback->($status)
		778	This is a rather advanced IO::AIO call, which only works on
		779	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		780	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		781	note that the scalar must only be modified in-place while an aio
		782	operation is pending on it).
		783
		784	It calls the "msync" function of your OS, if available, with the
		785	memory area starting at $offset in the string and ending $length
		786	bytes later. If $length is negative, counts from the end, and if
		787	$length is "undef", then it goes till the end of the string. The
		788	flags can be a combination of "IO::AIO::MS_ASYNC",
		789	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		790
		791	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		792	$callback->($status)
		793	This is a rather advanced IO::AIO call, which works best on
		794	mmap(2)ed scalars.
		795
		796	It touches (reads or writes) all memory pages in the specified range
		797	inside the scalar. All caveats and parameters are the same as for
		798	"aio_msync", above, except for flags, which must be either 0 (which
		799	reads all pages and ensures they are instantiated) or
		800	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		801	and writing an octet from it, which dirties the page).
		802
		803	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		804	This is a rather advanced IO::AIO call, which works best on
		805	mmap(2)ed scalars.
		806
		807	It reads in all the pages of the underlying storage into memory (if
		808	any) and locks them, so they are not getting swapped/paged out or
		809	removed.
		810
		811	If $length is undefined, then the scalar will be locked till the
		812	end.
		813
		814	On systems that do not implement "mlock", this function returns -1
		815	and sets errno to "ENOSYS".
		816
		817	Note that the corresponding "munlock" is synchronous and is
		818	documented under "MISCELLANEOUS FUNCTIONS".
		819
		820	Example: open a file, mmap and mlock it - both will be undone when
		821	$data gets destroyed.
		822
		823	open my $fh, "<", $path or die "$path: $!";
		824	my $data;
		825	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		826	aio_mlock $data; # mlock in background
		827
		828	aio_mlockall $flags, $callback->($status)
		829	Calls the "mlockall" function with the given $flags (a combination
		830	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		831
		832	On systems that do not implement "mlockall", this function returns
		833	-1 and sets errno to "ENOSYS".
		834
		835	Note that the corresponding "munlockall" is synchronous and is
		836	documented under "MISCELLANEOUS FUNCTIONS".
		837
		838	Example: asynchronously lock all current and future pages into
		839	memory.
		840
		841	aio_mlockall IO::AIO::MCL_FUTURE;
		842
641	aio_group $callback->(...)	843	aio_group $callback->(...)
642	This is a very special aio request: Instead of doing something, it	844	This is a very special aio request: Instead of doing something, it
643	is a container for other aio requests, which is useful if you want	845	is a container for other aio requests, which is useful if you want
644	to bundle many requests into a single, composite, request with a	846	to bundle many requests into a single, composite, request with a
645	definite callback and the ability to cancel the whole request with	847	definite callback and the ability to cancel the whole request with
…		…
760		962
761	$grp->cancel_subs	963	$grp->cancel_subs
762	Cancel all subrequests and clears any feeder, but not the group	964	Cancel all subrequests and clears any feeder, but not the group
763	request itself. Useful when you queued a lot of events but got a	965	request itself. Useful when you queued a lot of events but got a
764	result early.	966	result early.
		967
		968	The group request will finish normally (you cannot add requests to
		969	the group).
765		970
766	$grp->result (...)	971	$grp->result (...)
767	Set the result value(s) that will be passed to the group callback	972	Set the result value(s) that will be passed to the group callback
768	when all subrequests have finished and set the groups errno to the	973	when all subrequests have finished and set the groups errno to the
769	current value of errno (just like calling "errno" without an error	974	current value of errno (just like calling "errno" without an error
…		…
837		1042
838	See "poll_cb" for an example.	1043	See "poll_cb" for an example.
839		1044
840	IO::AIO::poll_cb	1045	IO::AIO::poll_cb
841	Process some outstanding events on the result pipe. You have to call	1046	Process some outstanding events on the result pipe. You have to call
842	this regularly. Returns 0 if all events could be processed, or -1 if	1047	this regularly. Returns 0 if all events could be processed (or there
843	it returned earlier for whatever reason. Returns immediately when no	1048	were no events to process), or -1 if it returned earlier for
844	events are outstanding. The amount of events processed depends on	1049	whatever reason. Returns immediately when no events are outstanding.
845	the settings of "IO::AIO::max_poll_req" and	1050	The amount of events processed depends on the settings of
846	"IO::AIO::max_poll_time".	1051	"IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".
847		1052
848	If not all requests were processed for whatever reason, the	1053	If not all requests were processed for whatever reason, the
849	filehandle will still be ready when "poll_cb" returns, so normally	1054	filehandle will still be ready when "poll_cb" returns, so normally
850	you don't have to do anything special to have it called later.	1055	you don't have to do anything special to have it called later.
851		1056
		1057	Apart from calling "IO::AIO::poll_cb" when the event filehandle
		1058	becomes ready, it can be beneficial to call this function from loops
		1059	which submit a lot of requests, to make sure the results get
		1060	processed when they become available and not just when the loop is
		1061	finished and the event loop takes over again. This function returns
		1062	very fast when there are no outstanding requests.
		1063
852	Example: Install an Event watcher that automatically calls	1064	Example: Install an Event watcher that automatically calls
853	IO::AIO::poll_cb with high priority (more examples can be found in	1065	IO::AIO::poll_cb with high priority (more examples can be found in
854	the SYNOPSIS section, at the top of this document):	1066	the SYNOPSIS section, at the top of this document):
855		1067
856	Event->io (fd => IO::AIO::poll_fileno,	1068	Event->io (fd => IO::AIO::poll_fileno,
857	poll => 'r', async => 1,	1069	poll => 'r', async => 1,
858	cb => \&IO::AIO::poll_cb);	1070	cb => \&IO::AIO::poll_cb);
		1071
		1072	IO::AIO::poll_wait
		1073	If there are any outstanding requests and none of them in the result
		1074	phase, wait till the result filehandle becomes ready for reading
		1075	(simply does a "select" on the filehandle. This is useful if you
		1076	want to synchronously wait for some requests to finish).
		1077
		1078	See "nreqs" for an example.
		1079
		1080	IO::AIO::poll
		1081	Waits until some requests have been handled.
		1082
		1083	Returns the number of requests processed, but is otherwise strictly
		1084	equivalent to:
		1085
		1086	IO::AIO::poll_wait, IO::AIO::poll_cb
		1087
		1088	IO::AIO::flush
		1089	Wait till all outstanding AIO requests have been handled.
		1090
		1091	Strictly equivalent to:
		1092
		1093	IO::AIO::poll_wait, IO::AIO::poll_cb
		1094	while IO::AIO::nreqs;
859		1095
860	IO::AIO::max_poll_reqs $nreqs	1096	IO::AIO::max_poll_reqs $nreqs
861	IO::AIO::max_poll_time $seconds	1097	IO::AIO::max_poll_time $seconds
862	These set the maximum number of requests (default 0, meaning	1098	These set the maximum number of requests (default 0, meaning
863	infinity) that are being processed by "IO::AIO::poll_cb" in one	1099	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
887	# use a low priority so other tasks have priority	1123	# use a low priority so other tasks have priority
888	Event->io (fd => IO::AIO::poll_fileno,	1124	Event->io (fd => IO::AIO::poll_fileno,
889	poll => 'r', nice => 1,	1125	poll => 'r', nice => 1,
890	cb => &IO::AIO::poll_cb);	1126	cb => &IO::AIO::poll_cb);
891		1127
892	IO::AIO::poll_wait
893	If there are any outstanding requests and none of them in the result
894	phase, wait till the result filehandle becomes ready for reading
895	(simply does a "select" on the filehandle. This is useful if you
896	want to synchronously wait for some requests to finish).
897
898	See "nreqs" for an example.
899
900	IO::AIO::poll
901	Waits until some requests have been handled.
902
903	Returns the number of requests processed, but is otherwise strictly
904	equivalent to:
905
906	IO::AIO::poll_wait, IO::AIO::poll_cb
907
908	IO::AIO::flush
909	Wait till all outstanding AIO requests have been handled.
910
911	Strictly equivalent to:
912
913	IO::AIO::poll_wait, IO::AIO::poll_cb
914	while IO::AIO::nreqs;
915
916	CONTROLLING THE NUMBER OF THREADS	1128	CONTROLLING THE NUMBER OF THREADS
917	IO::AIO::min_parallel $nthreads	1129	IO::AIO::min_parallel $nthreads
918	Set the minimum number of AIO threads to $nthreads. The current	1130	Set the minimum number of AIO threads to $nthreads. The current
919	default is 8, which means eight asynchronous operations can execute	1131	default is 8, which means eight asynchronous operations can execute
920	concurrently at any one time (the number of outstanding requests,	1132	concurrently at any one time (the number of outstanding requests,
…		…
949		1161
950	Under normal circumstances you don't need to call this function.	1162	Under normal circumstances you don't need to call this function.
951		1163
952	IO::AIO::max_idle $nthreads	1164	IO::AIO::max_idle $nthreads
953	Limit the number of threads (default: 4) that are allowed to idle	1165	Limit the number of threads (default: 4) that are allowed to idle
954	(i.e., threads that did not get a request to process within 10	1166	(i.e., threads that did not get a request to process within the idle
955	seconds). That means if a thread becomes idle while $nthreads other	1167	timeout (default: 10 seconds). That means if a thread becomes idle
956	threads are also idle, it will free its resources and exit.	1168	while $nthreads other threads are also idle, it will free its
		1169	resources and exit.
957		1170
958	This is useful when you allow a large number of threads (e.g. 100 or	1171	This is useful when you allow a large number of threads (e.g. 100 or
959	1000) to allow for extremely high load situations, but want to free	1172	1000) to allow for extremely high load situations, but want to free
960	resources under normal circumstances (1000 threads can easily	1173	resources under normal circumstances (1000 threads can easily
961	consume 30MB of RAM).	1174	consume 30MB of RAM).
962		1175
963	The default is probably ok in most situations, especially if thread	1176	The default is probably ok in most situations, especially if thread
964	creation is fast. If thread creation is very slow on your system you	1177	creation is fast. If thread creation is very slow on your system you
965	might want to use larger values.	1178	might want to use larger values.
966		1179
		1180	IO::AIO::idle_timeout $seconds
		1181	Sets the minimum idle timeout (default 10) after which worker
		1182	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1183
967	IO::AIO::max_outstanding $maxreqs	1184	IO::AIO::max_outstanding $maxreqs
		1185	Sets the maximum number of outstanding requests to $nreqs. If you do
		1186	queue up more than this number of requests, the next call to
		1187	"IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
		1188	"IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
		1189	no longer exceeded.
		1190
		1191	In other words, this setting does not enforce a queue limit, but can
		1192	be used to make poll functions block if the limit is exceeded.
		1193
968	This is a very bad function to use in interactive programs because	1194	This is a very bad function to use in interactive programs because
969	it blocks, and a bad way to reduce concurrency because it is	1195	it blocks, and a bad way to reduce concurrency because it is
970	inexact: Better use an "aio_group" together with a feed callback.	1196	inexact: Better use an "aio_group" together with a feed callback.
971		1197
972	Sets the maximum number of outstanding requests to $nreqs. If you do	1198	It's main use is in scripts without an event loop - when you want to
973	queue up more than this number of requests, the next call to the	1199	stat a lot of files, you can write somehting like this:
974	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
975	function will block until the limit is no longer exceeded.
976		1200
977	The default value is very large, so there is no practical limit on	1201	IO::AIO::max_outstanding 32;
		1202
		1203	for my $path (...) {
		1204	aio_stat $path , ...;
		1205	IO::AIO::poll_cb;
		1206	}
		1207
		1208	IO::AIO::flush;
		1209
		1210	The call to "poll_cb" inside the loop will normally return
		1211	instantly, but as soon as more thna 32 reqeusts are in-flight, it
		1212	will block until some requests have been handled. This keeps the
		1213	loop from pushing a large number of "aio_stat" requests onto the
		1214	queue.
		1215
		1216	The default value for "max_outstanding" is very large, so there is
978	the number of outstanding requests.	1217	no practical limit on the number of outstanding requests.
979
980	You can still queue as many requests as you want. Therefore,
981	"max_outstanding" is mainly useful in simple scripts (with low
982	values) or as a stop gap to shield against fatal memory overflow
983	(with large values).
984		1218
985	STATISTICAL INFORMATION	1219	STATISTICAL INFORMATION
986	IO::AIO::nreqs	1220	IO::AIO::nreqs
987	Returns the number of requests currently in the ready, execute or	1221	Returns the number of requests currently in the ready, execute or
988	pending states (i.e. for which their callback has not been invoked	1222	pending states (i.e. for which their callback has not been invoked
…		…
1012	set to non-blocking operations).	1246	set to non-blocking operations).
1013		1247
1014	Returns the number of bytes copied, or -1 on error.	1248	Returns the number of bytes copied, or -1 on error.
1015		1249
1016	IO::AIO::fadvise $fh, $offset, $len, $advice	1250	IO::AIO::fadvise $fh, $offset, $len, $advice
1017	Simply calls the "posix_fadvise" function (see it's manpage for	1251	Simply calls the "posix_fadvise" function (see its manpage for
1018	details). The following advice constants are avaiable:	1252	details). The following advice constants are avaiable:
1019	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",	1253	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1020	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",	1254	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1021	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".	1255	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1022		1256
1023	On systems that do not implement "posix_fadvise", this function	1257	On systems that do not implement "posix_fadvise", this function
1024	returns ENOSYS, otherwise the return value of "posix_fadvise".	1258	returns ENOSYS, otherwise the return value of "posix_fadvise".
1025		1259
		1260	IO::AIO::madvise $scalar, $offset, $len, $advice
		1261	Simply calls the "posix_madvise" function (see its manpage for
		1262	details). The following advice constants are avaiable:
		1263	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1264	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1265	"IO::AIO::MADV_DONTNEED".
		1266
		1267	On systems that do not implement "posix_madvise", this function
		1268	returns ENOSYS, otherwise the return value of "posix_madvise".
		1269
		1270	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1271	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1272	$scalar (see its manpage for details). The following protect
		1273	constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1274	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1275
		1276	On systems that do not implement "mprotect", this function returns
		1277	ENOSYS, otherwise the return value of "mprotect".
		1278
		1279	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1280	Memory-maps a file (or anonymous memory range) and attaches it to
		1281	the given $scalar, which will act like a string scalar.
		1282
		1283	The only operations allowed on the scalar are "substr"/"vec" that
		1284	don't change the string length, and most read-only operations such
		1285	as copying it or searching it with regexes and so on.
		1286
		1287	Anything else is unsafe and will, at best, result in memory leaks.
		1288
		1289	The memory map associated with the $scalar is automatically removed
		1290	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1291	"IO::AIO::munmap" functions are called.
		1292
		1293	This calls the "mmap"(2) function internally. See your system's
		1294	manual page for details on the $length, $prot and $flags parameters.
		1295
		1296	The $length must be larger than zero and smaller than the actual
		1297	filesize.
		1298
		1299	$prot is a combination of "IO::AIO::PROT_NONE",
		1300	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1301	"IO::AIO::PROT_WRITE",
		1302
		1303	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1304	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1305	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1306	(which is set to "MAP_ANON" if your system only provides this
		1307	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1308	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1309	"IO::AIO::MAP_NONBLOCK"
		1310
		1311	If $fh is "undef", then a file descriptor of -1 is passed.
		1312
		1313	$offset is the offset from the start of the file - it generally must
		1314	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1315
		1316	Example:
		1317
		1318	use Digest::MD5;
		1319	use IO::AIO;
		1320
		1321	open my $fh, "<verybigfile"
		1322	or die "$!";
		1323
		1324	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1325	or die "verybigfile: $!";
		1326
		1327	my $fast_md5 = md5 $data;
		1328
		1329	IO::AIO::munmap $scalar
		1330	Removes a previous mmap and undefines the $scalar.
		1331
		1332	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1333	Calls the "munlock" function, undoing the effects of a previous
		1334	"aio_mlock" call (see its description for details).
		1335
		1336	IO::AIO::munlockall
		1337	Calls the "munlockall" function.
		1338
		1339	On systems that do not implement "munlockall", this function returns
		1340	ENOSYS, otherwise the return value of "munlockall".
		1341
		1342	EVENT LOOP INTEGRATION
		1343	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1344	automatically into many event loops:
		1345
		1346	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1347	use AnyEvent::AIO;
		1348
		1349	You can also integrate IO::AIO manually into many event loops, here are
		1350	some examples of how to do this:
		1351
		1352	# EV integration
		1353	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1354
		1355	# Event integration
		1356	Event->io (fd => IO::AIO::poll_fileno,
		1357	poll => 'r',
		1358	cb => \&IO::AIO::poll_cb);
		1359
		1360	# Glib/Gtk2 integration
		1361	add_watch Glib::IO IO::AIO::poll_fileno,
		1362	in => sub { IO::AIO::poll_cb; 1 };
		1363
		1364	# Tk integration
		1365	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1366	readable => \&IO::AIO::poll_cb);
		1367
		1368	# Danga::Socket integration
		1369	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1370	\&IO::AIO::poll_cb);
		1371
1026	FORK BEHAVIOUR	1372	FORK BEHAVIOUR
1027	This module should do "the right thing" when the process using it forks:	1373	Usage of pthreads in a program changes the semantics of fork
		1374	considerably. Specifically, only async-safe functions can be called
		1375	after fork. Perl doesn't know about this, so in general, you cannot call
		1376	fork with defined behaviour in perl. IO::AIO uses pthreads, so this
		1377	applies, but many other extensions and (for inexplicable reasons) perl
		1378	itself often is linked against pthreads, so this limitation applies.
1028		1379
1029	Before the fork, IO::AIO enters a quiescent state where no requests can	1380	Some operating systems have extensions that allow safe use of fork, and
1030	be added in other threads and no results will be processed. After the	1381	this module should do "the right thing" on those, and tries on others.
1031	fork the parent simply leaves the quiescent state and continues	1382	At the time of this writing (2011) only GNU/Linux supports these
1032	request/result processing, while the child frees the request/result	1383	extensions to POSIX.
1033	queue (so that the requests started before the fork will only be handled
1034	in the parent). Threads will be started on demand until the limit set in
1035	the parent process has been reached again.
1036
1037	In short: the parent will, after a short pause, continue as if fork had
1038	not been called, while the child will act as if IO::AIO has not been
1039	used yet.
1040		1384
1041	MEMORY USAGE	1385	MEMORY USAGE
1042	Per-request usage:	1386	Per-request usage:
1043		1387
1044	Each aio request uses - depending on your architecture - around 100-200	1388	Each aio request uses - depending on your architecture - around 100-200

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Revision 1.39 by root, Wed Aug 5 11:53:16 2009 UTC vs.
Revision 1.48 by root, Wed Jun 29 11:25:17 2011 UTC