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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.193 by root, Thu May 26 04:15:37 2011 UTC vs.
Revision 1.278 by root, Sun Oct 1 07:24:34 2017 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '3.8';	176	our $VERSION = 4.35;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		182	aio_pathsync aio_readahead aio_fiemap aio_allocate
179	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
181	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
182	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
183	aio_statvfs);	187	aio_statvfs
		188	aio_wd);
184		189
185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	190	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	191	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
187	min_parallel max_parallel max_idle idle_timeout	192	min_parallel max_parallel max_idle idle_timeout
188	nreqs nready npending nthreads	193	nreqs nready npending nthreads
…		…
200		205
201	=head1 FUNCTIONS	206	=head1 FUNCTIONS
202		207
203	=head2 QUICK OVERVIEW	208	=head2 QUICK OVERVIEW
204		209
205	This section simply lists the prototypes of the most important functions	210	This section simply lists the prototypes most of the functions for
206	for quick reference. See the following sections for function-by-function	211	quick reference. See the following sections for function-by-function
207	documentation.	212	documentation.
208		213
		214	aio_wd $pathname, $callback->($wd)
209	aio_open $pathname, $flags, $mode, $callback->($fh)	215	aio_open $pathname, $flags, $mode, $callback->($fh)
210	aio_close $fh, $callback->($status)	216	aio_close $fh, $callback->($status)
		217	aio_seek $fh,$offset,$whence, $callback->($offs)
211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	218	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	220	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214	aio_readahead $fh,$offset,$length, $callback->($retval)	221	aio_readahead $fh,$offset,$length, $callback->($retval)
215	aio_stat $fh_or_path, $callback->($status)	222	aio_stat $fh_or_path, $callback->($status)
216	aio_lstat $fh, $callback->($status)	223	aio_lstat $fh, $callback->($status)
217	aio_statvfs $fh_or_path, $callback->($statvfs)	224	aio_statvfs $fh_or_path, $callback->($statvfs)
218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	225	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	226	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		227	aio_chmod $fh_or_path, $mode, $callback->($status)
220	aio_truncate $fh_or_path, $offset, $callback->($status)	228	aio_truncate $fh_or_path, $offset, $callback->($status)
221	aio_chmod $fh_or_path, $mode, $callback->($status)	229	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		230	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
222	aio_unlink $pathname, $callback->($status)	231	aio_unlink $pathname, $callback->($status)
223	aio_mknod $path, $mode, $dev, $callback->($status)	232	aio_mknod $pathname, $mode, $dev, $callback->($status)
224	aio_link $srcpath, $dstpath, $callback->($status)	233	aio_link $srcpath, $dstpath, $callback->($status)
225	aio_symlink $srcpath, $dstpath, $callback->($status)	234	aio_symlink $srcpath, $dstpath, $callback->($status)
226	aio_readlink $path, $callback->($link)	235	aio_readlink $pathname, $callback->($link)
		236	aio_realpath $pathname, $callback->($path)
227	aio_rename $srcpath, $dstpath, $callback->($status)	237	aio_rename $srcpath, $dstpath, $callback->($status)
		238	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
228	aio_mkdir $pathname, $mode, $callback->($status)	239	aio_mkdir $pathname, $mode, $callback->($status)
229	aio_rmdir $pathname, $callback->($status)	240	aio_rmdir $pathname, $callback->($status)
230	aio_readdir $pathname, $callback->($entries)	241	aio_readdir $pathname, $callback->($entries)
231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	242	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	243	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	244	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		245	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
234	aio_load $path, $data, $callback->($status)	246	aio_load $pathname, $data, $callback->($status)
235	aio_copy $srcpath, $dstpath, $callback->($status)	247	aio_copy $srcpath, $dstpath, $callback->($status)
236	aio_move $srcpath, $dstpath, $callback->($status)	248	aio_move $srcpath, $dstpath, $callback->($status)
237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238	aio_rmtree $path, $callback->($status)	249	aio_rmtree $pathname, $callback->($status)
		250	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		251	aio_ioctl $fh, $request, $buf, $callback->($status)
239	aio_sync $callback->($status)	252	aio_sync $callback->($status)
		253	aio_syncfs $fh, $callback->($status)
240	aio_fsync $fh, $callback->($status)	254	aio_fsync $fh, $callback->($status)
241	aio_fdatasync $fh, $callback->($status)	255	aio_fdatasync $fh, $callback->($status)
242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	256	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243	aio_pathsync $path, $callback->($status)	257	aio_pathsync $pathname, $callback->($status)
244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	258	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	260	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247	aio_mlockall $flags, $callback->($status)	261	aio_mlockall $flags, $callback->($status)
248	aio_group $callback->(...)	262	aio_group $callback->(...)
249	aio_nop $callback->()	263	aio_nop $callback->()
…		…
263	IO::AIO::idle_timeout $seconds	277	IO::AIO::idle_timeout $seconds
264	IO::AIO::max_outstanding $maxreqs	278	IO::AIO::max_outstanding $maxreqs
265	IO::AIO::nreqs	279	IO::AIO::nreqs
266	IO::AIO::nready	280	IO::AIO::nready
267	IO::AIO::npending	281	IO::AIO::npending
		282	$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
		283	IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
268		284
269	IO::AIO::sendfile $ofh, $ifh, $offset, $count	285	IO::AIO::sendfile $ofh, $ifh, $offset, $count
270	IO::AIO::fadvise $fh, $offset, $len, $advice	286	IO::AIO::fadvise $fh, $offset, $len, $advice
		287	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		288	IO::AIO::munmap $scalar
271	IO::AIO::madvise $scalar, $offset, $length, $advice	289	IO::AIO::madvise $scalar, $offset, $length, $advice
272	IO::AIO::mprotect $scalar, $offset, $length, $protect	290	IO::AIO::mprotect $scalar, $offset, $length, $protect
273	IO::AIO::munlock $scalar, $offset = 0, $length = undef	291	IO::AIO::munlock $scalar, $offset = 0, $length = undef
274	IO::AIO::munlockall	292	IO::AIO::munlockall
275		293
276	=head2 AIO REQUEST FUNCTIONS	294	=head2 API NOTES
277		295
278	All the C<aio_*> calls are more or less thin wrappers around the syscall	296	All the C<aio_*> calls are more or less thin wrappers around the syscall
279	with the same name (sans C<aio_>). The arguments are similar or identical,	297	with the same name (sans C<aio_>). The arguments are similar or identical,
280	and they all accept an additional (and optional) C<$callback> argument	298	and they all accept an additional (and optional) C<$callback> argument
281	which must be a code reference. This code reference will get called with	299	which must be a code reference. This code reference will be called after
282	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	300	the syscall has been executed in an asynchronous fashion. The results
283	perl, which usually delivers "false") as its sole argument after the given	301	of the request will be passed as arguments to the callback (and, if an
284	syscall has been executed asynchronously.	302	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		303	most syscalls return C<-1> on error, unlike perl, which usually delivers
		304	"false").
		305
		306	Some requests (such as C<aio_readdir>) pass the actual results and
		307	communicate failures by passing C<undef>.
285		308
286	All functions expecting a filehandle keep a copy of the filehandle	309	All functions expecting a filehandle keep a copy of the filehandle
287	internally until the request has finished.	310	internally until the request has finished.
288		311
289	All functions return request objects of type L<IO::AIO::REQ> that allow	312	All functions return request objects of type L<IO::AIO::REQ> that allow
290	further manipulation of those requests while they are in-flight.	313	further manipulation of those requests while they are in-flight.
291		314
292	The pathnames you pass to these routines I<must> be absolute and	315	The pathnames you pass to these routines I<should> be absolute. The
293	encoded as octets. The reason for the former is that at the time the	316	reason for this is that at the time the request is being executed, the
294	request is being executed, the current working directory could have	317	current working directory could have changed. Alternatively, you can
295	changed. Alternatively, you can make sure that you never change the	318	make sure that you never change the current working directory anywhere
296	current working directory anywhere in the program and then use relative	319	in the program and then use relative paths. You can also take advantage
297	paths.	320	of IO::AIOs working directory abstraction, that lets you specify paths
		321	relative to some previously-opened "working directory object" - see the
		322	description of the C<IO::AIO::WD> class later in this document.
298		323
299	To encode pathnames as octets, either make sure you either: a) always pass	324	To encode pathnames as octets, either make sure you either: a) always pass
300	in filenames you got from outside (command line, readdir etc.) without	325	in filenames you got from outside (command line, readdir etc.) without
301	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	326	tinkering, b) are in your native filesystem encoding, c) use the Encode
302	your pathnames to the locale (or other) encoding in effect in the user	327	module and encode your pathnames to the locale (or other) encoding in
303	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	328	effect in the user environment, d) use Glib::filename_from_unicode on
304	use something else to ensure your scalar has the correct contents.	329	unicode filenames or e) use something else to ensure your scalar has the
		330	correct contents.
305		331
306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	332	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
307	handles correctly whether it is set or not.	333	handles correctly whether it is set or not.
		334
		335	=head2 AIO REQUEST FUNCTIONS
308		336
309	=over 4	337	=over 4
310		338
311	=item $prev_pri = aioreq_pri [$pri]	339	=item $prev_pri = aioreq_pri [$pri]
312		340
…		…
342		370
343		371
344	=item aio_open $pathname, $flags, $mode, $callback->($fh)	372	=item aio_open $pathname, $flags, $mode, $callback->($fh)
345		373
346	Asynchronously open or create a file and call the callback with a newly	374	Asynchronously open or create a file and call the callback with a newly
347	created filehandle for the file.	375	created filehandle for the file (or C<undef> in case of an error).
348		376
349	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	377	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
350	for an explanation.	378	for an explanation.
351		379
352	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	380	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
368	} else {	396	} else {
369	die "open failed: $!\n";	397	die "open failed: $!\n";
370	}	398	}
371	};	399	};
372		400
		401	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		402	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		403	following POSIX and non-POSIX constants are available (missing ones on
		404	your system are, as usual, C<0>):
		405
		406	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		407	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		408	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		409
373		410
374	=item aio_close $fh, $callback->($status)	411	=item aio_close $fh, $callback->($status)
375		412
376	Asynchronously close a file and call the callback with the result	413	Asynchronously close a file and call the callback with the result
377	code.	414	code.
…		…
386	Or in other words: the file descriptor will be closed, but it will not be	423	Or in other words: the file descriptor will be closed, but it will not be
387	free for reuse until the perl filehandle is closed.	424	free for reuse until the perl filehandle is closed.
388		425
389	=cut	426	=cut
390		427
		428	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		429
		430	Seeks the filehandle to the new C<$offset>, similarly to perl's
		431	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		432	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		433	C<IO::AIO::SEEK_END>).
		434
		435	The resulting absolute offset will be passed to the callback, or C<-1> in
		436	case of an error.
		437
		438	In theory, the C<$whence> constants could be different than the
		439	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		440	so don't panic.
		441
		442	As a GNU/Linux (and maybe Solaris) extension, also the constants
		443	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		444	could be found. No guarantees about suitability for use in C<aio_seek> or
		445	Perl's C<sysseek> can be made though, although I would naively assume they
		446	"just work".
		447
391	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	448	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
392		449
393	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	450	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
394		451
395	Reads or writes C<$length> bytes from or to the specified C<$fh> and	452	Reads or writes C<$length> bytes from or to the specified C<$fh> and
396	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	453	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
397	and calls the callback without the actual number of bytes read (or -1 on	454	calls the callback with the actual number of bytes transferred (or -1 on
398	error, just like the syscall).	455	error, just like the syscall).
399		456
400	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	457	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
401	offset plus the actual number of bytes read.	458	offset plus the actual number of bytes read.
402		459
…		…
427		484
428	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	485	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
429	reading at byte offset C<$in_offset>, and starts writing at the current	486	reading at byte offset C<$in_offset>, and starts writing at the current
430	file offset of C<$out_fh>. Because of that, it is not safe to issue more	487	file offset of C<$out_fh>. Because of that, it is not safe to issue more
431	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	488	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
432	other.	489	other. The same C<$in_fh> works fine though, as this function does not
		490	move or use the file offset of C<$in_fh>.
433		491
434	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than	492	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
435	are written, and there is no way to find out how many bytes have been read	493	are written, and there is no way to find out how many more bytes have been
436	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of	494	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
437	bytes written to C<$out_fh>. Only if the result value equals C<$length>	495	number of bytes written to C<$out_fh>. Only if the result value equals
438	one can assume that C<$length> bytes have been read.	496	C<$length> one can assume that C<$length> bytes have been read.
439		497
440	Unlike with other C<aio_> functions, it makes a lot of sense to use	498	Unlike with other C<aio_> functions, it makes a lot of sense to use
441	C<aio_sendfile> on non-blocking sockets, as long as one end (typically	499	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
442	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while	500	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
443	the socket I/O will be non-blocking. Note, however, that you can run into	501	the socket I/O will be non-blocking. Note, however, that you can run
444	a trap where C<aio_sendfile> reads some data with readahead, then fails	502	into a trap where C<aio_sendfile> reads some data with readahead, then
445	to write all data, and when the socket is ready the next time, the data	503	fails to write all data, and when the socket is ready the next time, the
446	in the cache is already lost, forcing C<aio_sendfile> to again hit the	504	data in the cache is already lost, forcing C<aio_sendfile> to again hit
447	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage	505	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
448	much better.	506	resource usage.
449		507
450	This call tries to make use of a native C<sendfile> syscall to provide	508	This call tries to make use of a native C<sendfile>-like syscall to
451	zero-copy operation. For this to work, C<$out_fh> should refer to a	509	provide zero-copy operation. For this to work, C<$out_fh> should refer to
452	socket, and C<$in_fh> should refer to an mmap'able file.	510	a socket, and C<$in_fh> should refer to an mmap'able file.
453		511
454	If a native sendfile cannot be found or it fails with C<ENOSYS>,	512	If a native sendfile cannot be found or it fails with C<ENOSYS>,
455	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	513	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
456	it will be emulated, so you can call C<aio_sendfile> on any type of	514	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
457	filehandle regardless of the limitations of the operating system.	515	type of filehandle regardless of the limitations of the operating system.
		516
		517	As native sendfile syscalls (as practically any non-POSIX interface hacked
		518	together in a hurry to improve benchmark numbers) tend to be rather buggy
		519	on many systems, this implementation tries to work around some known bugs
		520	in Linux and FreeBSD kernels (probably others, too), but that might fail,
		521	so you really really should check the return value of C<aio_sendfile> -
		522	fewer bytes than expected might have been transferred.
458		523
459		524
460	=item aio_readahead $fh,$offset,$length, $callback->($retval)	525	=item aio_readahead $fh,$offset,$length, $callback->($retval)
461		526
462	C<aio_readahead> populates the page cache with data from a file so that	527	C<aio_readahead> populates the page cache with data from a file so that
…		…
466	whole pages, so that offset is effectively rounded down to a page boundary	531	whole pages, so that offset is effectively rounded down to a page boundary
467	and bytes are read up to the next page boundary greater than or equal to	532	and bytes are read up to the next page boundary greater than or equal to
468	(off-set+length). C<aio_readahead> does not read beyond the end of the	533	(off-set+length). C<aio_readahead> does not read beyond the end of the
469	file. The current file offset of the file is left unchanged.	534	file. The current file offset of the file is left unchanged.
470		535
471	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	536	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
472	emulated by simply reading the data, which would have a similar effect.	537	be emulated by simply reading the data, which would have a similar effect.
473		538
474		539
475	=item aio_stat $fh_or_path, $callback->($status)	540	=item aio_stat $fh_or_path, $callback->($status)
476		541
477	=item aio_lstat $fh, $callback->($status)	542	=item aio_lstat $fh, $callback->($status)
…		…
546	namemax => 255,	611	namemax => 255,
547	frsize => 1024,	612	frsize => 1024,
548	fsid => 1810	613	fsid => 1810
549	}	614	}
550		615
		616	Here is a (likely partial - send me updates!) list of fsid values used by
		617	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		618
		619	0x0000adf5 adfs
		620	0x0000adff affs
		621	0x5346414f afs
		622	0x09041934 anon-inode filesystem
		623	0x00000187 autofs
		624	0x42465331 befs
		625	0x1badface bfs
		626	0x42494e4d binfmt_misc
		627	0x9123683e btrfs
		628	0x0027e0eb cgroupfs
		629	0xff534d42 cifs
		630	0x73757245 coda
		631	0x012ff7b7 coh
		632	0x28cd3d45 cramfs
		633	0x453dcd28 cramfs-wend (wrong endianness)
		634	0x64626720 debugfs
		635	0x00001373 devfs
		636	0x00001cd1 devpts
		637	0x0000f15f ecryptfs
		638	0x00414a53 efs
		639	0x0000137d ext
		640	0x0000ef53 ext2/ext3/ext4
		641	0x0000ef51 ext2
		642	0xf2f52010 f2fs
		643	0x00004006 fat
		644	0x65735546 fuseblk
		645	0x65735543 fusectl
		646	0x0bad1dea futexfs
		647	0x01161970 gfs2
		648	0x47504653 gpfs
		649	0x00004244 hfs
		650	0xf995e849 hpfs
		651	0x00c0ffee hostfs
		652	0x958458f6 hugetlbfs
		653	0x2bad1dea inotifyfs
		654	0x00009660 isofs
		655	0x000072b6 jffs2
		656	0x3153464a jfs
		657	0x6b414653 k-afs
		658	0x0bd00bd0 lustre
		659	0x0000137f minix
		660	0x0000138f minix 30 char names
		661	0x00002468 minix v2
		662	0x00002478 minix v2 30 char names
		663	0x00004d5a minix v3
		664	0x19800202 mqueue
		665	0x00004d44 msdos
		666	0x0000564c novell
		667	0x00006969 nfs
		668	0x6e667364 nfsd
		669	0x00003434 nilfs
		670	0x5346544e ntfs
		671	0x00009fa1 openprom
		672	0x7461636F ocfs2
		673	0x00009fa0 proc
		674	0x6165676c pstorefs
		675	0x0000002f qnx4
		676	0x68191122 qnx6
		677	0x858458f6 ramfs
		678	0x52654973 reiserfs
		679	0x00007275 romfs
		680	0x67596969 rpc_pipefs
		681	0x73636673 securityfs
		682	0xf97cff8c selinux
		683	0x0000517b smb
		684	0x534f434b sockfs
		685	0x73717368 squashfs
		686	0x62656572 sysfs
		687	0x012ff7b6 sysv2
		688	0x012ff7b5 sysv4
		689	0x01021994 tmpfs
		690	0x15013346 udf
		691	0x00011954 ufs
		692	0x54190100 ufs byteswapped
		693	0x00009fa2 usbdevfs
		694	0x01021997 v9fs
		695	0xa501fcf5 vxfs
		696	0xabba1974 xenfs
		697	0x012ff7b4 xenix
		698	0x58465342 xfs
		699	0x012fd16d xia
551		700
552	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	701	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
553		702
554	Works like perl's C<utime> function (including the special case of $atime	703	Works like perl's C<utime> function (including the special case of $atime
555	and $mtime being undef). Fractional times are supported if the underlying	704	and $mtime being undef). Fractional times are supported if the underlying
…		…
583	=item aio_truncate $fh_or_path, $offset, $callback->($status)	732	=item aio_truncate $fh_or_path, $offset, $callback->($status)
584		733
585	Works like truncate(2) or ftruncate(2).	734	Works like truncate(2) or ftruncate(2).
586		735
587		736
		737	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		738
		739	Allocates or frees disk space according to the C<$mode> argument. See the
		740	linux C<fallocate> documentation for details.
		741
		742	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		743	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE \| IO::AIO::FALLOC_FL_KEEP_SIZE>,
		744	to deallocate a file range.
		745
		746	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		747	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		748	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		749	to unshare shared blocks (see your L<fallocate(2)> manpage).
		750
		751	The file system block size used by C<fallocate> is presumably the
		752	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		753	can dictate other limitations.
		754
		755	If C<fallocate> isn't available or cannot be emulated (currently no
		756	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		757
		758
588	=item aio_chmod $fh_or_path, $mode, $callback->($status)	759	=item aio_chmod $fh_or_path, $mode, $callback->($status)
589		760
590	Works like perl's C<chmod> function.	761	Works like perl's C<chmod> function.
591		762
592		763
…		…
594		765
595	Asynchronously unlink (delete) a file and call the callback with the	766	Asynchronously unlink (delete) a file and call the callback with the
596	result code.	767	result code.
597		768
598		769
599	=item aio_mknod $path, $mode, $dev, $callback->($status)	770	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
600		771
601	[EXPERIMENTAL]	772	[EXPERIMENTAL]
602		773
603	Asynchronously create a device node (or fifo). See mknod(2).	774	Asynchronously create a device node (or fifo). See mknod(2).
604		775
605	The only (POSIX-) portable way of calling this function is:	776	The only (POSIX-) portable way of calling this function is:
606		777
607	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	778	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
608		779
609	See C<aio_stat> for info about some potentially helpful extra constants	780	See C<aio_stat> for info about some potentially helpful extra constants
610	and functions.	781	and functions.
611		782
612	=item aio_link $srcpath, $dstpath, $callback->($status)	783	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
619		790
620	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	791	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
621	the path C<$dstpath> and call the callback with the result code.	792	the path C<$dstpath> and call the callback with the result code.
622		793
623		794
624	=item aio_readlink $path, $callback->($link)	795	=item aio_readlink $pathname, $callback->($link)
625		796
626	Asynchronously read the symlink specified by C<$path> and pass it to	797	Asynchronously read the symlink specified by C<$path> and pass it to
627	the callback. If an error occurs, nothing or undef gets passed to the	798	the callback. If an error occurs, nothing or undef gets passed to the
628	callback.	799	callback.
629		800
630		801
		802	=item aio_realpath $pathname, $callback->($path)
		803
		804	Asynchronously make the path absolute and resolve any symlinks in
		805	C<$path>. The resulting path only consists of directories (same as
		806	L<Cwd::realpath>).
		807
		808	This request can be used to get the absolute path of the current working
		809	directory by passing it a path of F<.> (a single dot).
		810
		811
631	=item aio_rename $srcpath, $dstpath, $callback->($status)	812	=item aio_rename $srcpath, $dstpath, $callback->($status)
632		813
633	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	814	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
634	rename(2) and call the callback with the result code.	815	rename(2) and call the callback with the result code.
		816
		817	On systems that support the AIO::WD working directory abstraction
		818	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		819	of failing, C<rename> is called on the absolute path of C<$wd>.
		820
		821
		822	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		823
		824	Basically a version of C<aio_rename> with an additional C<$flags>
		825	argument. Calling this with C<$flags=0> is the same as calling
		826	C<aio_rename>.
		827
		828	Non-zero flags are currently only supported on GNU/Linux systems that
		829	support renameat2. Other systems fail with C<ENOSYS> in this case.
		830
		831	The following constants are available (missing ones are, as usual C<0>),
		832	see renameat2(2) for details:
		833
		834	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		835	and C<IO::AIO::RENAME_WHITEOUT>.
635		836
636		837
637	=item aio_mkdir $pathname, $mode, $callback->($status)	838	=item aio_mkdir $pathname, $mode, $callback->($status)
638		839
639	Asynchronously mkdir (create) a directory and call the callback with	840	Asynchronously mkdir (create) a directory and call the callback with
…		…
644	=item aio_rmdir $pathname, $callback->($status)	845	=item aio_rmdir $pathname, $callback->($status)
645		846
646	Asynchronously rmdir (delete) a directory and call the callback with the	847	Asynchronously rmdir (delete) a directory and call the callback with the
647	result code.	848	result code.
648		849
		850	On systems that support the AIO::WD working directory abstraction
		851	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		852	C<rmdir> is called on the absolute path of C<$wd>.
		853
649		854
650	=item aio_readdir $pathname, $callback->($entries)	855	=item aio_readdir $pathname, $callback->($entries)
651		856
652	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	857	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
653	directory (i.e. opendir + readdir + closedir). The entries will not be	858	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
657	array-ref with the filenames.	862	array-ref with the filenames.
658		863
659		864
660	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	865	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
661		866
662	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	867	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
663	behaviour and output format. In case of an error, C<$entries> will be	868	tune behaviour and output format. In case of an error, C<$entries> will be
664	C<undef>.	869	C<undef>.
665		870
666	The flags are a combination of the following constants, ORed together (the	871	The flags are a combination of the following constants, ORed together (the
667	flags will also be passed to the callback, possibly modified):	872	flags will also be passed to the callback, possibly modified):
668		873
…		…
715		920
716	=item IO::AIO::READDIR_FOUND_UNKNOWN	921	=item IO::AIO::READDIR_FOUND_UNKNOWN
717		922
718	This flag should not be set when calling C<aio_readdirx>. Instead, it	923	This flag should not be set when calling C<aio_readdirx>. Instead, it
719	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	924	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
720	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	925	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
721	C<$type>'s are known, which can be used to speed up some algorithms.	926	C<$type>'s are known, which can be used to speed up some algorithms.
722		927
723	=back	928	=back
724		929
725		930
726	=item aio_load $path, $data, $callback->($status)	931	=item aio_load $pathname, $data, $callback->($status)
727		932
728	This is a composite request that tries to fully load the given file into	933	This is a composite request that tries to fully load the given file into
729	memory. Status is the same as with aio_read.	934	memory. Status is the same as with aio_read.
730		935
731	=cut	936	=cut
…		…
754	=item aio_copy $srcpath, $dstpath, $callback->($status)	959	=item aio_copy $srcpath, $dstpath, $callback->($status)
755		960
756	Try to copy the I<file> (directories not supported as either source or	961	Try to copy the I<file> (directories not supported as either source or
757	destination) from C<$srcpath> to C<$dstpath> and call the callback with	962	destination) from C<$srcpath> to C<$dstpath> and call the callback with
758	a status of C<0> (ok) or C<-1> (error, see C<$!>).	963	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		964
		965	Existing destination files will be truncated.
759		966
760	This is a composite request that creates the destination file with	967	This is a composite request that creates the destination file with
761	mode 0200 and copies the contents of the source file into it using	968	mode 0200 and copies the contents of the source file into it using
762	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	969	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
763	uid/gid, in that order.	970	uid/gid, in that order.
…		…
853	if ($_[0] && $! == EXDEV) {	1060	if ($_[0] && $! == EXDEV) {
854	aioreq_pri $pri;	1061	aioreq_pri $pri;
855	add $grp aio_copy $src, $dst, sub {	1062	add $grp aio_copy $src, $dst, sub {
856	$grp->result ($_[0]);	1063	$grp->result ($_[0]);
857		1064
858	if (!$_[0]) {	1065	unless ($_[0]) {
859	aioreq_pri $pri;	1066	aioreq_pri $pri;
860	add $grp aio_unlink $src;	1067	add $grp aio_unlink $src;
861	}	1068	}
862	};	1069	};
863	} else {	1070	} else {
…		…
866	};	1073	};
867		1074
868	$grp	1075	$grp
869	}	1076	}
870		1077
871	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1078	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
872		1079
873	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1080	Scans a directory (similar to C<aio_readdir>) but additionally tries to
874	efficiently separate the entries of directory C<$path> into two sets of	1081	efficiently separate the entries of directory C<$path> into two sets of
875	names, directories you can recurse into (directories), and ones you cannot	1082	names, directories you can recurse into (directories), and ones you cannot
876	recurse into (everything else, including symlinks to directories).	1083	recurse into (everything else, including symlinks to directories).
877		1084
878	C<aio_scandir> is a composite request that creates of many sub requests_	1085	C<aio_scandir> is a composite request that generates many sub requests.
879	C<$maxreq> specifies the maximum number of outstanding aio requests that	1086	C<$maxreq> specifies the maximum number of outstanding aio requests that
880	this function generates. If it is C<< <= 0 >>, then a suitable default	1087	this function generates. If it is C<< <= 0 >>, then a suitable default
881	will be chosen (currently 4).	1088	will be chosen (currently 4).
882		1089
883	On error, the callback is called without arguments, otherwise it receives	1090	On error, the callback is called without arguments, otherwise it receives
…		…
907	Then entries will be sorted into likely directories a non-initial dot	1114	Then entries will be sorted into likely directories a non-initial dot
908	currently) and likely non-directories (see C<aio_readdirx>). Then every	1115	currently) and likely non-directories (see C<aio_readdirx>). Then every
909	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1116	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
910	in order of their inode numbers. If that succeeds, it assumes that the	1117	in order of their inode numbers. If that succeeds, it assumes that the
911	entry is a directory or a symlink to directory (which will be checked	1118	entry is a directory or a symlink to directory (which will be checked
912	seperately). This is often faster than stat'ing the entry itself because	1119	separately). This is often faster than stat'ing the entry itself because
913	filesystems might detect the type of the entry without reading the inode	1120	filesystems might detect the type of the entry without reading the inode
914	data (e.g. ext2fs filetype feature), even on systems that cannot return	1121	data (e.g. ext2fs filetype feature), even on systems that cannot return
915	the filetype information on readdir.	1122	the filetype information on readdir.
916		1123
917	If the known number of directories (link count - 2) has been reached, the	1124	If the known number of directories (link count - 2) has been reached, the
…		…
933		1140
934	my $grp = aio_group $cb;	1141	my $grp = aio_group $cb;
935		1142
936	$maxreq = 4 if $maxreq <= 0;	1143	$maxreq = 4 if $maxreq <= 0;
937		1144
938	# stat once	1145	# get a wd object
939	aioreq_pri $pri;	1146	aioreq_pri $pri;
940	add $grp aio_stat $path, sub {	1147	add $grp aio_wd $path, sub {
		1148	$_[0]
941	return $grp->result () if $_[0];	1149	or return $grp->result ();
942	my $now = time;
943	my $hash1 = join ":", (stat _)[0,1,3,7,9];
944		1150
945	# read the directory entries	1151	my $wd = [shift, "."];
		1152
		1153	# stat once
946	aioreq_pri $pri;	1154	aioreq_pri $pri;
947	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1155	add $grp aio_stat $wd, sub {
948	my $entries = shift
949	or return $grp->result ();	1156	return $grp->result () if $_[0];
		1157	my $now = time;
		1158	my $hash1 = join ":", (stat _)[0,1,3,7,9];
950		1159
951	# stat the dir another time	1160	# read the directory entries
952	aioreq_pri $pri;	1161	aioreq_pri $pri;
		1162	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1163	my $entries = shift
		1164	or return $grp->result ();
		1165
		1166	# stat the dir another time
		1167	aioreq_pri $pri;
953	add $grp aio_stat $path, sub {	1168	add $grp aio_stat $wd, sub {
954	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1169	my $hash2 = join ":", (stat _)[0,1,3,7,9];
955		1170
956	my $ndirs;	1171	my $ndirs;
957		1172
958	# take the slow route if anything looks fishy	1173	# take the slow route if anything looks fishy
959	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1174	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
960	$ndirs = -1;	1175	$ndirs = -1;
961	} else {	1176	} else {
962	# if nlink == 2, we are finished	1177	# if nlink == 2, we are finished
963	# for non-posix-fs's, we rely on nlink < 2	1178	# for non-posix-fs's, we rely on nlink < 2
964	$ndirs = (stat _)[3] - 2	1179	$ndirs = (stat _)[3] - 2
965	or return $grp->result ([], $entries);	1180	or return $grp->result ([], $entries);
966	}	1181	}
967		1182
968	my (@dirs, @nondirs);	1183	my (@dirs, @nondirs);
969		1184
970	my $statgrp = add $grp aio_group sub {	1185	my $statgrp = add $grp aio_group sub {
971	$grp->result (\@dirs, \@nondirs);	1186	$grp->result (\@dirs, \@nondirs);
972	};	1187	};
973		1188
974	limit $statgrp $maxreq;	1189	limit $statgrp $maxreq;
975	feed $statgrp sub {	1190	feed $statgrp sub {
976	return unless @$entries;	1191	return unless @$entries;
977	my $entry = shift @$entries;	1192	my $entry = shift @$entries;
978		1193
979	aioreq_pri $pri;	1194	aioreq_pri $pri;
		1195	$wd->[1] = "$entry/.";
980	add $statgrp aio_stat "$path/$entry/.", sub {	1196	add $statgrp aio_stat $wd, sub {
981	if ($_[0] < 0) {	1197	if ($_[0] < 0) {
982	push @nondirs, $entry;	1198	push @nondirs, $entry;
983	} else {	1199	} else {
984	# need to check for real directory	1200	# need to check for real directory
985	aioreq_pri $pri;	1201	aioreq_pri $pri;
		1202	$wd->[1] = $entry;
986	add $statgrp aio_lstat "$path/$entry", sub {	1203	add $statgrp aio_lstat $wd, sub {
987	if (-d _) {	1204	if (-d _) {
988	push @dirs, $entry;	1205	push @dirs, $entry;
989		1206
990	unless (--$ndirs) {	1207	unless (--$ndirs) {
991	push @nondirs, @$entries;	1208	push @nondirs, @$entries;
992	feed $statgrp;	1209	feed $statgrp;
		1210	}
		1211	} else {
		1212	push @nondirs, $entry;
993	}	1213	}
994	} else {
995	push @nondirs, $entry;
996	}	1214	}
997	}	1215	}
998	}	1216	};
999	};	1217	};
1000	};	1218	};
1001	};	1219	};
1002	};	1220	};
1003	};	1221	};
1004		1222
1005	$grp	1223	$grp
1006	}	1224	}
1007		1225
1008	=item aio_rmtree $path, $callback->($status)	1226	=item aio_rmtree $pathname, $callback->($status)
1009		1227
1010	Delete a directory tree starting (and including) C<$path>, return the	1228	Delete a directory tree starting (and including) C<$path>, return the
1011	status of the final C<rmdir> only. This is a composite request that	1229	status of the final C<rmdir> only. This is a composite request that
1012	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1230	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1013	everything else.	1231	everything else.
1014		1232
1015	=cut	1233	=cut
1016		1234
…		…
1038	};	1256	};
1039		1257
1040	$grp	1258	$grp
1041	}	1259	}
1042		1260
		1261	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1262
		1263	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1264
		1265	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1266	they execute asynchronously and pass the return value to the callback.
		1267
		1268	Both calls can be used for a lot of things, some of which make more sense
		1269	to run asynchronously in their own thread, while some others make less
		1270	sense. For example, calls that block waiting for external events, such
		1271	as locking, will also lock down an I/O thread while it is waiting, which
		1272	can deadlock the whole I/O system. At the same time, there might be no
		1273	alternative to using a thread to wait.
		1274
		1275	So in general, you should only use these calls for things that do
		1276	(filesystem) I/O, not for things that wait for other events (network,
		1277	other processes), although if you are careful and know what you are doing,
		1278	you still can.
		1279
		1280	The following constants are available (missing ones are, as usual C<0>):
		1281
		1282	C<F_DUPFD_CLOEXEC>,
		1283
		1284	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1285
		1286	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1287
		1288	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1289	C<FS_IOC_FIEMAP>.
		1290
		1291	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1292	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1293
		1294	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1295	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1296	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1297	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1298	C<FS_FL_USER_MODIFIABLE>.
		1299
		1300	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1301	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1302	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1303	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1304
1043	=item aio_sync $callback->($status)	1305	=item aio_sync $callback->($status)
1044		1306
1045	Asynchronously call sync and call the callback when finished.	1307	Asynchronously call sync and call the callback when finished.
1046		1308
1047	=item aio_fsync $fh, $callback->($status)	1309	=item aio_fsync $fh, $callback->($status)
…		…
1054	Asynchronously call fdatasync on the given filehandle and call the	1316	Asynchronously call fdatasync on the given filehandle and call the
1055	callback with the fdatasync result code.	1317	callback with the fdatasync result code.
1056		1318
1057	If this call isn't available because your OS lacks it or it couldn't be	1319	If this call isn't available because your OS lacks it or it couldn't be
1058	detected, it will be emulated by calling C<fsync> instead.	1320	detected, it will be emulated by calling C<fsync> instead.
		1321
		1322	=item aio_syncfs $fh, $callback->($status)
		1323
		1324	Asynchronously call the syncfs syscall to sync the filesystem associated
		1325	to the given filehandle and call the callback with the syncfs result
		1326	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1327	errno to C<ENOSYS> nevertheless.
1059		1328
1060	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1329	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1061		1330
1062	Sync the data portion of the file specified by C<$offset> and C<$length>	1331	Sync the data portion of the file specified by C<$offset> and C<$length>
1063	to disk (but NOT the metadata), by calling the Linux-specific	1332	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1067	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1336	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1068	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1337	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1069	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1338	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1070	manpage for details.	1339	manpage for details.
1071		1340
1072	=item aio_pathsync $path, $callback->($status)	1341	=item aio_pathsync $pathname, $callback->($status)
1073		1342
1074	This request tries to open, fsync and close the given path. This is a	1343	This request tries to open, fsync and close the given path. This is a
1075	composite request intended to sync directories after directory operations	1344	composite request intended to sync directories after directory operations
1076	(E.g. rename). This might not work on all operating systems or have any	1345	(E.g. rename). This might not work on all operating systems or have any
1077	specific effect, but usually it makes sure that directory changes get	1346	specific effect, but usually it makes sure that directory changes get
…		…
1108	};	1377	};
1109		1378
1110	$grp	1379	$grp
1111	}	1380	}
1112		1381
1113	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1382	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1114		1383
1115	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1384	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1116	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1385	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1117	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1386	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1118	scalar must only be modified in-place while an aio operation is pending on	1387	scalar must only be modified in-place while an aio operation is pending on
…		…
1120		1389
1121	It calls the C<msync> function of your OS, if available, with the memory	1390	It calls the C<msync> function of your OS, if available, with the memory
1122	area starting at C<$offset> in the string and ending C<$length> bytes	1391	area starting at C<$offset> in the string and ending C<$length> bytes
1123	later. If C<$length> is negative, counts from the end, and if C<$length>	1392	later. If C<$length> is negative, counts from the end, and if C<$length>
1124	is C<undef>, then it goes till the end of the string. The flags can be	1393	is C<undef>, then it goes till the end of the string. The flags can be
1125	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1394	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1126	C<IO::AIO::MS_SYNC>.	1395	C<IO::AIO::MS_INVALIDATE>.
1127		1396
1128	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1397	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1129		1398
1130	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1399	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1131	scalars.	1400	scalars.
1132		1401
1133	It touches (reads or writes) all memory pages in the specified	1402	It touches (reads or writes) all memory pages in the specified
1134	range inside the scalar. All caveats and parameters are the same	1403	range inside the scalar. All caveats and parameters are the same
1135	as for C<aio_msync>, above, except for flags, which must be either	1404	as for C<aio_msync>, above, except for flags, which must be either
1136	C<0> (which reads all pages and ensures they are instantiated) or	1405	C<0> (which reads all pages and ensures they are instantiated) or
1137	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1406	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1138	writing an octet from it, which dirties the page).	1407	writing an octet from it, which dirties the page).
1139		1408
1140	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1409	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1141		1410
1142	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1411	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1173	documented under L<MISCELLANEOUS FUNCTIONS>.	1442	documented under L<MISCELLANEOUS FUNCTIONS>.
1174		1443
1175	Example: asynchronously lock all current and future pages into memory.	1444	Example: asynchronously lock all current and future pages into memory.
1176		1445
1177	aio_mlockall IO::AIO::MCL_FUTURE;	1446	aio_mlockall IO::AIO::MCL_FUTURE;
		1447
		1448	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1449
		1450	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1451	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1452	the ioctl is not available on your OS, then this request will fail with
		1453	C<ENOSYS>.
		1454
		1455	C<$start> is the starting offset to query extents for, C<$length> is the
		1456	size of the range to query - if it is C<undef>, then the whole file will
		1457	be queried.
		1458
		1459	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1460	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1461	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1462	the data portion.
		1463
		1464	C<$count> is the maximum number of extent records to return. If it is
		1465	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1466	case, if it is C<0>, then the callback receives the number of extents
		1467	instead of the extents themselves (which is unreliable, see below).
		1468
		1469	If an error occurs, the callback receives no arguments. The special
		1470	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1471
		1472	Otherwise, the callback receives an array reference with extent
		1473	structures. Each extent structure is an array reference itself, with the
		1474	following members:
		1475
		1476	[$logical, $physical, $length, $flags]
		1477
		1478	Flags is any combination of the following flag values (typically either C<0>
		1479	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1480
		1481	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1482	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1483	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1484	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1485	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1486	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1487
		1488	At the time of this writing (Linux 3.2), this request is unreliable unless
		1489	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1490	it to return all extents of a range for files with a large number of
		1491	extents. The code (only) works around all these issues if C<$count> is
		1492	C<undef>.
1178		1493
1179	=item aio_group $callback->(...)	1494	=item aio_group $callback->(...)
1180		1495
1181	This is a very special aio request: Instead of doing something, it is a	1496	This is a very special aio request: Instead of doing something, it is a
1182	container for other aio requests, which is useful if you want to bundle	1497	container for other aio requests, which is useful if you want to bundle
…		…
1219	like sleep and file handle readable/writable, the overhead this creates is	1534	like sleep and file handle readable/writable, the overhead this creates is
1220	immense (it blocks a thread for a long time) so do not use this function	1535	immense (it blocks a thread for a long time) so do not use this function
1221	except to put your application under artificial I/O pressure.	1536	except to put your application under artificial I/O pressure.
1222		1537
1223	=back	1538	=back
		1539
		1540
		1541	=head2 IO::AIO::WD - multiple working directories
		1542
		1543	Your process only has one current working directory, which is used by all
		1544	threads. This makes it hard to use relative paths (some other component
		1545	could call C<chdir> at any time, and it is hard to control when the path
		1546	will be used by IO::AIO).
		1547
		1548	One solution for this is to always use absolute paths. This usually works,
		1549	but can be quite slow (the kernel has to walk the whole path on every
		1550	access), and can also be a hassle to implement.
		1551
		1552	Newer POSIX systems have a number of functions (openat, fdopendir,
		1553	futimensat and so on) that make it possible to specify working directories
		1554	per operation.
		1555
		1556	For portability, and because the clowns who "designed", or shall I write,
		1557	perpetrated this new interface were obviously half-drunk, this abstraction
		1558	cannot be perfect, though.
		1559
		1560	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1561	object. This object stores the canonicalised, absolute version of the
		1562	path, and on systems that allow it, also a directory file descriptor.
		1563
		1564	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1565	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1566	object and a pathname instead (or the IO::AIO::WD object alone, which
		1567	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1568	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1569	to that IO::AIO::WD object.
		1570
		1571	For example, to get a wd object for F</etc> and then stat F<passwd>
		1572	inside, you would write:
		1573
		1574	aio_wd "/etc", sub {
		1575	my $etcdir = shift;
		1576
		1577	# although $etcdir can be undef on error, there is generally no reason
		1578	# to check for errors here, as aio_stat will fail with ENOENT
		1579	# when $etcdir is undef.
		1580
		1581	aio_stat [$etcdir, "passwd"], sub {
		1582	# yay
		1583	};
		1584	};
		1585
		1586	The fact that C<aio_wd> is a request and not a normal function shows that
		1587	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1588	which is why it is done asynchronously.
		1589
		1590	To stat the directory obtained with C<aio_wd> above, one could write
		1591	either of the following three request calls:
		1592
		1593	aio_lstat "/etc" , sub { ... # pathname as normal string
		1594	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1595	aio_lstat $wd , sub { ... # shorthand for the previous
		1596
		1597	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1598	object and the pathname string, so you could write the following without
		1599	causing any issues due to C<$path> getting reused:
		1600
		1601	my $path = [$wd, undef];
		1602
		1603	for my $name (qw(abc def ghi)) {
		1604	$path->[1] = $name;
		1605	aio_stat $path, sub {
		1606	# ...
		1607	};
		1608	}
		1609
		1610	There are some caveats: when directories get renamed (or deleted), the
		1611	pathname string doesn't change, so will point to the new directory (or
		1612	nowhere at all), while the directory fd, if available on the system,
		1613	will still point to the original directory. Most functions accepting a
		1614	pathname will use the directory fd on newer systems, and the string on
		1615	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1616	the string form of the pathname.
		1617
		1618	So this functionality is mainly useful to get some protection against
		1619	C<chdir>, to easily get an absolute path out of a relative path for future
		1620	reference, and to speed up doing many operations in the same directory
		1621	(e.g. when stat'ing all files in a directory).
		1622
		1623	The following functions implement this working directory abstraction:
		1624
		1625	=over 4
		1626
		1627	=item aio_wd $pathname, $callback->($wd)
		1628
		1629	Asynchonously canonicalise the given pathname and convert it to an
		1630	IO::AIO::WD object representing it. If possible and supported on the
		1631	system, also open a directory fd to speed up pathname resolution relative
		1632	to this working directory.
		1633
		1634	If something goes wrong, then C<undef> is passwd to the callback instead
		1635	of a working directory object and C<$!> is set appropriately. Since
		1636	passing C<undef> as working directory component of a pathname fails the
		1637	request with C<ENOENT>, there is often no need for error checking in the
		1638	C<aio_wd> callback, as future requests using the value will fail in the
		1639	expected way.
		1640
		1641	=item IO::AIO::CWD
		1642
		1643	This is a compiletime constant (object) that represents the process
		1644	current working directory.
		1645
		1646	Specifying this object as working directory object for a pathname is as if
		1647	the pathname would be specified directly, without a directory object. For
		1648	example, these calls are functionally identical:
		1649
		1650	aio_stat "somefile", sub { ... };
		1651	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1652
		1653	=back
		1654
		1655	To recover the path associated with an IO::AIO::WD object, you can use
		1656	C<aio_realpath>:
		1657
		1658	aio_realpath $wd, sub {
		1659	warn "path is $_[0]\n";
		1660	};
		1661
		1662	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1663	sometimes, fall back to using an absolue path.
1224		1664
1225	=head2 IO::AIO::REQ CLASS	1665	=head2 IO::AIO::REQ CLASS
1226		1666
1227	All non-aggregate C<aio_*> functions return an object of this class when	1667	All non-aggregate C<aio_*> functions return an object of this class when
1228	called in non-void context.	1668	called in non-void context.
…		…
1346		1786
1347	Sets a feeder/generator on this group: every group can have an attached	1787	Sets a feeder/generator on this group: every group can have an attached
1348	generator that generates requests if idle. The idea behind this is that,	1788	generator that generates requests if idle. The idea behind this is that,
1349	although you could just queue as many requests as you want in a group,	1789	although you could just queue as many requests as you want in a group,
1350	this might starve other requests for a potentially long time. For example,	1790	this might starve other requests for a potentially long time. For example,
1351	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1791	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1352	delaying any later requests for a long time.	1792	requests, delaying any later requests for a long time.
1353		1793
1354	To avoid this, and allow incremental generation of requests, you can	1794	To avoid this, and allow incremental generation of requests, you can
1355	instead a group and set a feeder on it that generates those requests. The	1795	instead a group and set a feeder on it that generates those requests. The
1356	feed callback will be called whenever there are few enough (see C<limit>,	1796	feed callback will be called whenever there are few enough (see C<limit>,
1357	below) requests active in the group itself and is expected to queue more	1797	below) requests active in the group itself and is expected to queue more
…		…
1406		1846
1407	See C<poll_cb> for an example.	1847	See C<poll_cb> for an example.
1408		1848
1409	=item IO::AIO::poll_cb	1849	=item IO::AIO::poll_cb
1410		1850
1411	Process some outstanding events on the result pipe. You have to call	1851	Process some requests that have reached the result phase (i.e. they have
		1852	been executed but the results are not yet reported). You have to call
		1853	this "regularly" to finish outstanding requests.
		1854
1412	this regularly. Returns C<0> if all events could be processed (or there	1855	Returns C<0> if all events could be processed (or there were no
1413	were no events to process), or C<-1> if it returned earlier for whatever	1856	events to process), or C<-1> if it returned earlier for whatever
1414	reason. Returns immediately when no events are outstanding. The amount of	1857	reason. Returns immediately when no events are outstanding. The amount
1415	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1858	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1416	C<IO::AIO::max_poll_time>.	1859	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1417		1860
1418	If not all requests were processed for whatever reason, the filehandle	1861	If not all requests were processed for whatever reason, the poll file
1419	will still be ready when C<poll_cb> returns, so normally you don't have to	1862	descriptor will still be ready when C<poll_cb> returns, so normally you
1420	do anything special to have it called later.	1863	don't have to do anything special to have it called later.
1421		1864
1422	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1865	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1423	ready, it can be beneficial to call this function from loops which submit	1866	ready, it can be beneficial to call this function from loops which submit
1424	a lot of requests, to make sure the results get processed when they become	1867	a lot of requests, to make sure the results get processed when they become
1425	available and not just when the loop is finished and the event loop takes	1868	available and not just when the loop is finished and the event loop takes
…		…
1434	poll => 'r', async => 1,	1877	poll => 'r', async => 1,
1435	cb => \&IO::AIO::poll_cb);	1878	cb => \&IO::AIO::poll_cb);
1436		1879
1437	=item IO::AIO::poll_wait	1880	=item IO::AIO::poll_wait
1438		1881
1439	If there are any outstanding requests and none of them in the result	1882	Wait until either at least one request is in the result phase or no
1440	phase, wait till the result filehandle becomes ready for reading (simply	1883	requests are outstanding anymore.
1441	does a C<select> on the filehandle. This is useful if you want to	1884
1442	synchronously wait for some requests to finish).	1885	This is useful if you want to synchronously wait for some requests to
		1886	become ready, without actually handling them.
1443		1887
1444	See C<nreqs> for an example.	1888	See C<nreqs> for an example.
1445		1889
1446	=item IO::AIO::poll	1890	=item IO::AIO::poll
1447		1891
…		…
1555	Sets the minimum idle timeout (default 10) after which worker threads are	1999	Sets the minimum idle timeout (default 10) after which worker threads are
1556	allowed to exit. SEe C<IO::AIO::max_idle>.	2000	allowed to exit. SEe C<IO::AIO::max_idle>.
1557		2001
1558	=item IO::AIO::max_outstanding $maxreqs	2002	=item IO::AIO::max_outstanding $maxreqs
1559		2003
		2004	Sets the maximum number of outstanding requests to C<$nreqs>. If
		2005	you do queue up more than this number of requests, the next call to
		2006	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		2007	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2008	longer exceeded.
		2009
		2010	In other words, this setting does not enforce a queue limit, but can be
		2011	used to make poll functions block if the limit is exceeded.
		2012
1560	This is a very bad function to use in interactive programs because it	2013	This is a very bad function to use in interactive programs because it
1561	blocks, and a bad way to reduce concurrency because it is inexact: Better	2014	blocks, and a bad way to reduce concurrency because it is inexact: Better
1562	use an C<aio_group> together with a feed callback.	2015	use an C<aio_group> together with a feed callback.
1563		2016
1564	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2017	Its main use is in scripts without an event loop - when you want to stat
1565	do queue up more than this number of requests, the next call to the	2018	a lot of files, you can write something like this:
1566	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1567	function will block until the limit is no longer exceeded.
1568		2019
1569	The default value is very large, so there is no practical limit on the	2020	IO::AIO::max_outstanding 32;
1570	number of outstanding requests.
1571		2021
1572	You can still queue as many requests as you want. Therefore,	2022	for my $path (...) {
1573	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2023	aio_stat $path , ...;
1574	as a stop gap to shield against fatal memory overflow (with large values).	2024	IO::AIO::poll_cb;
		2025	}
		2026
		2027	IO::AIO::flush;
		2028
		2029	The call to C<poll_cb> inside the loop will normally return instantly, but
		2030	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2031	some requests have been handled. This keeps the loop from pushing a large
		2032	number of C<aio_stat> requests onto the queue.
		2033
		2034	The default value for C<max_outstanding> is very large, so there is no
		2035	practical limit on the number of outstanding requests.
1575		2036
1576	=back	2037	=back
1577		2038
1578	=head3 STATISTICAL INFORMATION	2039	=head3 STATISTICAL INFORMATION
1579		2040
…		…
1601		2062
1602	=back	2063	=back
1603		2064
1604	=head3 MISCELLANEOUS FUNCTIONS	2065	=head3 MISCELLANEOUS FUNCTIONS
1605		2066
1606	IO::AIO implements some functions that might be useful, but are not	2067	IO::AIO implements some functions that are useful when you want to use
1607	asynchronous.	2068	some "Advanced I/O" function not available to in Perl, without going the
		2069	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2070	counterpart.
1608		2071
1609	=over 4	2072	=over 4
		2073
		2074	=item $numfd = IO::AIO::get_fdlimit
		2075
		2076	This function is I<EXPERIMENTAL> and subject to change.
		2077
		2078	Tries to find the current file descriptor limit and returns it, or
		2079	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2080	the highest valid file descriptor number.
		2081
		2082	=item IO::AIO::min_fdlimit [$numfd]
		2083
		2084	This function is I<EXPERIMENTAL> and subject to change.
		2085
		2086	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2087	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2088	is missing, it will try to set a very high limit, although this is not
		2089	recommended when you know the actual minimum that you require.
		2090
		2091	If the limit cannot be raised enough, the function makes a best-effort
		2092	attempt to increase the limit as much as possible, using various
		2093	tricks, while still failing. You can query the resulting limit using
		2094	C<IO::AIO::get_fdlimit>.
		2095
		2096	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2097	true.
1610		2098
1611	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2099	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1612		2100
1613	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2101	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1614	but is blocking (this makes most sense if you know the input data is	2102	but is blocking (this makes most sense if you know the input data is
…		…
1619		2107
1620	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2108	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1621		2109
1622	Simply calls the C<posix_fadvise> function (see its	2110	Simply calls the C<posix_fadvise> function (see its
1623	manpage for details). The following advice constants are	2111	manpage for details). The following advice constants are
1624	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2112	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1625	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2113	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1626	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2114	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1627		2115
1628	On systems that do not implement C<posix_fadvise>, this function returns	2116	On systems that do not implement C<posix_fadvise>, this function returns
1629	ENOSYS, otherwise the return value of C<posix_fadvise>.	2117	ENOSYS, otherwise the return value of C<posix_fadvise>.
1630		2118
1631	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2119	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1632		2120
1633	Simply calls the C<posix_madvise> function (see its	2121	Simply calls the C<posix_madvise> function (see its
1634	manpage for details). The following advice constants are	2122	manpage for details). The following advice constants are
1635	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2123	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1636	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2124	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2125	C<IO::AIO::MADV_DONTNEED>.
		2126
		2127	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2128	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2129	will be reduced to fit into the C<$scalar>.
1637		2130
1638	On systems that do not implement C<posix_madvise>, this function returns	2131	On systems that do not implement C<posix_madvise>, this function returns
1639	ENOSYS, otherwise the return value of C<posix_madvise>.	2132	ENOSYS, otherwise the return value of C<posix_madvise>.
1640		2133
1641	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2134	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1642		2135
1643	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2136	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1644	$scalar (see its manpage for details). The following protect	2137	$scalar (see its manpage for details). The following protect
1645	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2138	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1646	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2139	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2140
		2141	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2142	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2143	will be reduced to fit into the C<$scalar>.
1647		2144
1648	On systems that do not implement C<mprotect>, this function returns	2145	On systems that do not implement C<mprotect>, this function returns
1649	ENOSYS, otherwise the return value of C<mprotect>.	2146	ENOSYS, otherwise the return value of C<mprotect>.
1650		2147
1651	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2148	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1652		2149
1653	Memory-maps a file (or anonymous memory range) and attaches it to the	2150	Memory-maps a file (or anonymous memory range) and attaches it to the
1654	given C<$scalar>, which will act like a string scalar.	2151	given C<$scalar>, which will act like a string scalar. Returns true on
		2152	success, and false otherwise.
1655		2153
		2154	The scalar must exist, but its contents do not matter - this means you
		2155	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2156	the scalar first.
		2157
1656	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2158	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1657	change the string length, and most read-only operations such as copying it	2159	which don't change the string length, and most read-only operations such
1658	or searching it with regexes and so on.	2160	as copying it or searching it with regexes and so on.
1659		2161
1660	Anything else is unsafe and will, at best, result in memory leaks.	2162	Anything else is unsafe and will, at best, result in memory leaks.
1661		2163
1662	The memory map associated with the C<$scalar> is automatically removed	2164	The memory map associated with the C<$scalar> is automatically removed
1663	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2165	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1664	C<IO::AIO::munmap> functions are called.	2166	or C<IO::AIO::munmap> functions are called on it.
1665		2167
1666	This calls the C<mmap>(2) function internally. See your system's manual	2168	This calls the C<mmap>(2) function internally. See your system's manual
1667	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2169	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1668		2170
1669	The C<$length> must be larger than zero and smaller than the actual	2171	The C<$length> must be larger than zero and smaller than the actual
1670	filesize.	2172	filesize.
1671		2173
1672	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2174	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1673	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2175	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1674		2176
1675	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2177	C<$flags> can be a combination of
1676	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2178	C<IO::AIO::MAP_SHARED> or
1677	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2179	C<IO::AIO::MAP_PRIVATE>,
		2180	or a number of system-specific flags (when not available, the are C<0>):
1678	(which is set to C<MAP_ANON> if your system only provides this	2181	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1679	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2182	C<IO::AIO::MAP_LOCKED>,
1680	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2183	C<IO::AIO::MAP_NORESERVE>,
		2184	C<IO::AIO::MAP_POPULATE>,
1681	C<IO::AIO::MAP_NONBLOCK>	2185	C<IO::AIO::MAP_NONBLOCK>,
		2186	C<IO::AIO::MAP_FIXED>,
		2187	C<IO::AIO::MAP_GROWSDOWN>,
		2188	C<IO::AIO::MAP_32BIT>,
		2189	C<IO::AIO::MAP_HUGETLB> or
		2190	C<IO::AIO::MAP_STACK>.
1682		2191
1683	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2192	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1684		2193
1685	C<$offset> is the offset from the start of the file - it generally must be	2194	C<$offset> is the offset from the start of the file - it generally must be
1686	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2195	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1711		2220
1712	Calls the C<munlockall> function.	2221	Calls the C<munlockall> function.
1713		2222
1714	On systems that do not implement C<munlockall>, this function returns	2223	On systems that do not implement C<munlockall>, this function returns
1715	ENOSYS, otherwise the return value of C<munlockall>.	2224	ENOSYS, otherwise the return value of C<munlockall>.
		2225
		2226	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2227
		2228	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2229	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2230	should be the file offset.
		2231
		2232	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2233	silently corrupt the data in this case.
		2234
		2235	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2236	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2237	C<IO::AIO::SPLICE_F_GIFT>.
		2238
		2239	See the C<splice(2)> manpage for details.
		2240
		2241	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2242
		2243	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2244	description for C<IO::AIO::splice> above for details.
		2245
		2246	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2247
		2248	Attempts to query or change the pipe buffer size. Obviously works only
		2249	on pipes, and currently works only on GNU/Linux systems, and fails with
		2250	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2251	size on other systems, drop me a note.
		2252
		2253	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2254
		2255	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2256	C<$flags> is missing or C<0>, then this should be the same as a call to
		2257	perl's built-in C<pipe> function and create a new pipe, and works on
		2258	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2259	(..., 4096, O_BINARY)>.
		2260
		2261	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2262	the given flags (Linux 2.6.27, glibc 2.9).
		2263
		2264	On success, the read and write file handles are returned.
		2265
		2266	On error, nothing will be returned. If the pipe2 syscall is missing and
		2267	C<$flags> is non-zero, fails with C<ENOSYS>.
		2268
		2269	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2270	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2271	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1716		2272
1717	=back	2273	=back
1718		2274
1719	=cut	2275	=cut
1720		2276
…		…
1755	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2311	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1756	\&IO::AIO::poll_cb);	2312	\&IO::AIO::poll_cb);
1757		2313
1758	=head2 FORK BEHAVIOUR	2314	=head2 FORK BEHAVIOUR
1759		2315
1760	This module should do "the right thing" when the process using it forks:	2316	Usage of pthreads in a program changes the semantics of fork
		2317	considerably. Specifically, only async-safe functions can be called after
		2318	fork. Perl doesn't know about this, so in general, you cannot call fork
		2319	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2320	pthreads, so this applies, but many other extensions and (for inexplicable
		2321	reasons) perl itself often is linked against pthreads, so this limitation
		2322	applies to quite a lot of perls.
1761		2323
1762	Before the fork, IO::AIO enters a quiescent state where no requests	2324	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1763	can be added in other threads and no results will be processed. After	2325	only works in the process that loaded it. Forking is fully supported, but
1764	the fork the parent simply leaves the quiescent state and continues	2326	using IO::AIO in the child is not.
1765	request/result processing, while the child frees the request/result queue
1766	(so that the requests started before the fork will only be handled in the
1767	parent). Threads will be started on demand until the limit set in the
1768	parent process has been reached again.
1769		2327
1770	In short: the parent will, after a short pause, continue as if fork had	2328	You might get around by not I<using> IO::AIO before (or after)
1771	not been called, while the child will act as if IO::AIO has not been used	2329	forking. You could also try to call the L<IO::AIO::reinit> function in the
1772	yet.	2330	child:
		2331
		2332	=over 4
		2333
		2334	=item IO::AIO::reinit
		2335
		2336	Abandons all current requests and I/O threads and simply reinitialises all
		2337	data structures. This is not an operation supported by any standards, but
		2338	happens to work on GNU/Linux and some newer BSD systems.
		2339
		2340	The only reasonable use for this function is to call it after forking, if
		2341	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2342	the process will result in undefined behaviour. Calling it at any time
		2343	will also result in any undefined (by POSIX) behaviour.
		2344
		2345	=back
1773		2346
1774	=head2 MEMORY USAGE	2347	=head2 MEMORY USAGE
1775		2348
1776	Per-request usage:	2349	Per-request usage:
1777		2350

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.193 by root, Thu May 26 04:15:37 2011 UTC vs. Revision 1.278 by root, Sun Oct 1 07:24:34 2017 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.193 by root, Thu May 26 04:15:37 2011 UTC vs.
Revision 1.278 by root, Sun Oct 1 07:24:34 2017 UTC