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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.211 by root, Tue Sep 27 12:10:29 2011 UTC vs.
Revision 1.281 by root, Tue Feb 20 04:32:59 2018 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 = '4.0';	176	our $VERSION = 4.4;
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_realpath aio_sync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179	aio_pathsync aio_readahead	182	aio_pathsync aio_readahead aio_fiemap aio_allocate
180	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181	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
182	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
183	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
184	aio_statvfs	187	aio_statvfs
		188	aio_slurp
185	aio_wd);	189	aio_wd);
186		190
187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
189	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
…		…
202		206
203	=head1 FUNCTIONS	207	=head1 FUNCTIONS
204		208
205	=head2 QUICK OVERVIEW	209	=head2 QUICK OVERVIEW
206		210
207	This section simply lists the prototypes of the most important functions	211	This section simply lists the prototypes most of the functions for
208	for quick reference. See the following sections for function-by-function	212	quick reference. See the following sections for function-by-function
209	documentation.	213	documentation.
210		214
211	aio_wd $pathname, $callback->($wd)	215	aio_wd $pathname, $callback->($wd)
212	aio_open $pathname, $flags, $mode, $callback->($fh)	216	aio_open $pathname, $flags, $mode, $callback->($fh)
213	aio_close $fh, $callback->($status)	217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217	aio_readahead $fh,$offset,$length, $callback->($retval)	222	aio_readahead $fh,$offset,$length, $callback->($retval)
218	aio_stat $fh_or_path, $callback->($status)	223	aio_stat $fh_or_path, $callback->($status)
219	aio_lstat $fh, $callback->($status)	224	aio_lstat $fh, $callback->($status)
220	aio_statvfs $fh_or_path, $callback->($statvfs)	225	aio_statvfs $fh_or_path, $callback->($statvfs)
221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	227	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		228	aio_chmod $fh_or_path, $mode, $callback->($status)
223	aio_truncate $fh_or_path, $offset, $callback->($status)	229	aio_truncate $fh_or_path, $offset, $callback->($status)
224	aio_chmod $fh_or_path, $mode, $callback->($status)	230	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		231	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
225	aio_unlink $pathname, $callback->($status)	232	aio_unlink $pathname, $callback->($status)
226	aio_mknod $pathname, $mode, $dev, $callback->($status)	233	aio_mknod $pathname, $mode, $dev, $callback->($status)
227	aio_link $srcpath, $dstpath, $callback->($status)	234	aio_link $srcpath, $dstpath, $callback->($status)
228	aio_symlink $srcpath, $dstpath, $callback->($status)	235	aio_symlink $srcpath, $dstpath, $callback->($status)
229	aio_readlink $pathname, $callback->($link)	236	aio_readlink $pathname, $callback->($link)
230	aio_realpath $pathname, $callback->($link)	237	aio_realpath $pathname, $callback->($path)
231	aio_rename $srcpath, $dstpath, $callback->($status)	238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
232	aio_mkdir $pathname, $mode, $callback->($status)	240	aio_mkdir $pathname, $mode, $callback->($status)
233	aio_rmdir $pathname, $callback->($status)	241	aio_rmdir $pathname, $callback->($status)
234	aio_readdir $pathname, $callback->($entries)	242	aio_readdir $pathname, $callback->($entries)
235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	245	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		246	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
238	aio_load $pathname, $data, $callback->($status)	247	aio_load $pathname, $data, $callback->($status)
239	aio_copy $srcpath, $dstpath, $callback->($status)	248	aio_copy $srcpath, $dstpath, $callback->($status)
240	aio_move $srcpath, $dstpath, $callback->($status)	249	aio_move $srcpath, $dstpath, $callback->($status)
241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242	aio_rmtree $pathname, $callback->($status)	250	aio_rmtree $pathname, $callback->($status)
		251	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		252	aio_ioctl $fh, $request, $buf, $callback->($status)
243	aio_sync $callback->($status)	253	aio_sync $callback->($status)
244	aio_syncfs $fh, $callback->($status)	254	aio_syncfs $fh, $callback->($status)
245	aio_fsync $fh, $callback->($status)	255	aio_fsync $fh, $callback->($status)
246	aio_fdatasync $fh, $callback->($status)	256	aio_fdatasync $fh, $callback->($status)
247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248	aio_pathsync $pathname, $callback->($status)	258	aio_pathsync $pathname, $callback->($status)
249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252	aio_mlockall $flags, $callback->($status)	262	aio_mlockall $flags, $callback->($status)
253	aio_group $callback->(...)	263	aio_group $callback->(...)
254	aio_nop $callback->()	264	aio_nop $callback->()
…		…
268	IO::AIO::idle_timeout $seconds	278	IO::AIO::idle_timeout $seconds
269	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
270	IO::AIO::nreqs	280	IO::AIO::nreqs
271	IO::AIO::nready	281	IO::AIO::nready
272	IO::AIO::npending	282	IO::AIO::npending
		283	$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
		284	IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
273		285
274	IO::AIO::sendfile $ofh, $ifh, $offset, $count	286	IO::AIO::sendfile $ofh, $ifh, $offset, $count
275	IO::AIO::fadvise $fh, $offset, $len, $advice	287	IO::AIO::fadvise $fh, $offset, $len, $advice
		288	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		289	IO::AIO::munmap $scalar
276	IO::AIO::madvise $scalar, $offset, $length, $advice	290	IO::AIO::madvise $scalar, $offset, $length, $advice
277	IO::AIO::mprotect $scalar, $offset, $length, $protect	291	IO::AIO::mprotect $scalar, $offset, $length, $protect
278	IO::AIO::munlock $scalar, $offset = 0, $length = undef	292	IO::AIO::munlock $scalar, $offset = 0, $length = undef
279	IO::AIO::munlockall	293	IO::AIO::munlockall
280		294
281	=head2 AIO REQUEST FUNCTIONS	295	=head2 API NOTES
282		296
283	All the C<aio_*> calls are more or less thin wrappers around the syscall	297	All the C<aio_*> calls are more or less thin wrappers around the syscall
284	with the same name (sans C<aio_>). The arguments are similar or identical,	298	with the same name (sans C<aio_>). The arguments are similar or identical,
285	and they all accept an additional (and optional) C<$callback> argument	299	and they all accept an additional (and optional) C<$callback> argument
286	which must be a code reference. This code reference will get called with	300	which must be a code reference. This code reference will be called after
287	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	301	the syscall has been executed in an asynchronous fashion. The results
288	perl, which usually delivers "false") as its sole argument after the given	302	of the request will be passed as arguments to the callback (and, if an
289	syscall has been executed asynchronously.	303	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		304	most syscalls return C<-1> on error, unlike perl, which usually delivers
		305	"false").
		306
		307	Some requests (such as C<aio_readdir>) pass the actual results and
		308	communicate failures by passing C<undef>.
290		309
291	All functions expecting a filehandle keep a copy of the filehandle	310	All functions expecting a filehandle keep a copy of the filehandle
292	internally until the request has finished.	311	internally until the request has finished.
293		312
294	All functions return request objects of type L<IO::AIO::REQ> that allow	313	All functions return request objects of type L<IO::AIO::REQ> that allow
295	further manipulation of those requests while they are in-flight.	314	further manipulation of those requests while they are in-flight.
296		315
297	The pathnames you pass to these routines I<should> be absolute. The	316	The pathnames you pass to these routines I<should> be absolute. The
298	reason for this is that at the time the request is being executed, the	317	reason for this is that at the time the request is being executed, the
299	current working directory could have changed. Alternatively, you can make	318	current working directory could have changed. Alternatively, you can
300	sure that you never change the current working directory anywhere in	319	make sure that you never change the current working directory anywhere
301	the program and then use relative paths. Lastly, you can take advantage	320	in the program and then use relative paths. You can also take advantage
302	of IO::AIOs working directory abstraction - see the description of the	321	of IO::AIOs working directory abstraction, that lets you specify paths
		322	relative to some previously-opened "working directory object" - see the
303	C<IO::AIO::WD> class later in this document.	323	description of the C<IO::AIO::WD> class later in this document.
304		324
305	To encode pathnames as octets, either make sure you either: a) always pass	325	To encode pathnames as octets, either make sure you either: a) always pass
306	in filenames you got from outside (command line, readdir etc.) without	326	in filenames you got from outside (command line, readdir etc.) without
307	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	327	tinkering, b) are in your native filesystem encoding, c) use the Encode
308	your pathnames to the locale (or other) encoding in effect in the user	328	module and encode your pathnames to the locale (or other) encoding in
309	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	329	effect in the user environment, d) use Glib::filename_from_unicode on
310	use something else to ensure your scalar has the correct contents.	330	unicode filenames or e) use something else to ensure your scalar has the
		331	correct contents.
311		332
312	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	333	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
313	handles correctly whether it is set or not.	334	handles correctly whether it is set or not.
		335
		336	=head2 AIO REQUEST FUNCTIONS
314		337
315	=over 4	338	=over 4
316		339
317	=item $prev_pri = aioreq_pri [$pri]	340	=item $prev_pri = aioreq_pri [$pri]
318		341
…		…
348		371
349		372
350	=item aio_open $pathname, $flags, $mode, $callback->($fh)	373	=item aio_open $pathname, $flags, $mode, $callback->($fh)
351		374
352	Asynchronously open or create a file and call the callback with a newly	375	Asynchronously open or create a file and call the callback with a newly
353	created filehandle for the file.	376	created filehandle for the file (or C<undef> in case of an error).
354		377
355	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	378	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
356	for an explanation.	379	for an explanation.
357		380
358	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	381	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
381	following POSIX and non-POSIX constants are available (missing ones on	404	following POSIX and non-POSIX constants are available (missing ones on
382	your system are, as usual, C<0>):	405	your system are, as usual, C<0>):
383		406
384	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	407	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
385	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	408	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
386	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	409	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
387		410
388		411
389	=item aio_close $fh, $callback->($status)	412	=item aio_close $fh, $callback->($status)
390		413
391	Asynchronously close a file and call the callback with the result	414	Asynchronously close a file and call the callback with the result
…		…
401	Or in other words: the file descriptor will be closed, but it will not be	424	Or in other words: the file descriptor will be closed, but it will not be
402	free for reuse until the perl filehandle is closed.	425	free for reuse until the perl filehandle is closed.
403		426
404	=cut	427	=cut
405		428
		429	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		430
		431	Seeks the filehandle to the new C<$offset>, similarly to perl's
		432	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		433	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		434	C<IO::AIO::SEEK_END>).
		435
		436	The resulting absolute offset will be passed to the callback, or C<-1> in
		437	case of an error.
		438
		439	In theory, the C<$whence> constants could be different than the
		440	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		441	so don't panic.
		442
		443	As a GNU/Linux (and maybe Solaris) extension, also the constants
		444	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		445	could be found. No guarantees about suitability for use in C<aio_seek> or
		446	Perl's C<sysseek> can be made though, although I would naively assume they
		447	"just work".
		448
406	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	449	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
407		450
408	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	451	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
409		452
410	Reads or writes C<$length> bytes from or to the specified C<$fh> and	453	Reads or writes C<$length> bytes from or to the specified C<$fh> and
411	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	454	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
412	and calls the callback without the actual number of bytes read (or -1 on	455	calls the callback with the actual number of bytes transferred (or -1 on
413	error, just like the syscall).	456	error, just like the syscall).
414		457
415	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	458	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
416	offset plus the actual number of bytes read.	459	offset plus the actual number of bytes read.
417		460
…		…
475	As native sendfile syscalls (as practically any non-POSIX interface hacked	518	As native sendfile syscalls (as practically any non-POSIX interface hacked
476	together in a hurry to improve benchmark numbers) tend to be rather buggy	519	together in a hurry to improve benchmark numbers) tend to be rather buggy
477	on many systems, this implementation tries to work around some known bugs	520	on many systems, this implementation tries to work around some known bugs
478	in Linux and FreeBSD kernels (probably others, too), but that might fail,	521	in Linux and FreeBSD kernels (probably others, too), but that might fail,
479	so you really really should check the return value of C<aio_sendfile> -	522	so you really really should check the return value of C<aio_sendfile> -
480	fewre bytes than expected might have been transferred.	523	fewer bytes than expected might have been transferred.
481		524
482		525
483	=item aio_readahead $fh,$offset,$length, $callback->($retval)	526	=item aio_readahead $fh,$offset,$length, $callback->($retval)
484		527
485	C<aio_readahead> populates the page cache with data from a file so that	528	C<aio_readahead> populates the page cache with data from a file so that
…		…
489	whole pages, so that offset is effectively rounded down to a page boundary	532	whole pages, so that offset is effectively rounded down to a page boundary
490	and bytes are read up to the next page boundary greater than or equal to	533	and bytes are read up to the next page boundary greater than or equal to
491	(off-set+length). C<aio_readahead> does not read beyond the end of the	534	(off-set+length). C<aio_readahead> does not read beyond the end of the
492	file. The current file offset of the file is left unchanged.	535	file. The current file offset of the file is left unchanged.
493		536
494	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	537	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
495	emulated by simply reading the data, which would have a similar effect.	538	be emulated by simply reading the data, which would have a similar effect.
496		539
497		540
498	=item aio_stat $fh_or_path, $callback->($status)	541	=item aio_stat $fh_or_path, $callback->($status)
499		542
500	=item aio_lstat $fh, $callback->($status)	543	=item aio_lstat $fh, $callback->($status)
…		…
569	namemax => 255,	612	namemax => 255,
570	frsize => 1024,	613	frsize => 1024,
571	fsid => 1810	614	fsid => 1810
572	}	615	}
573		616
574
575	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	617	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
576		618
577	Works like perl's C<utime> function (including the special case of $atime	619	Works like perl's C<utime> function (including the special case of $atime
578	and $mtime being undef). Fractional times are supported if the underlying	620	and $mtime being undef). Fractional times are supported if the underlying
579	syscalls support them.	621	syscalls support them.
…		…
606	=item aio_truncate $fh_or_path, $offset, $callback->($status)	648	=item aio_truncate $fh_or_path, $offset, $callback->($status)
607		649
608	Works like truncate(2) or ftruncate(2).	650	Works like truncate(2) or ftruncate(2).
609		651
610		652
		653	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		654
		655	Allocates or frees disk space according to the C<$mode> argument. See the
		656	linux C<fallocate> documentation for details.
		657
		658	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		659	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE \| IO::AIO::FALLOC_FL_KEEP_SIZE>,
		660	to deallocate a file range.
		661
		662	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		663	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		664	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		665	to unshare shared blocks (see your L<fallocate(2)> manpage).
		666
		667	The file system block size used by C<fallocate> is presumably the
		668	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		669	can dictate other limitations.
		670
		671	If C<fallocate> isn't available or cannot be emulated (currently no
		672	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		673
		674
611	=item aio_chmod $fh_or_path, $mode, $callback->($status)	675	=item aio_chmod $fh_or_path, $mode, $callback->($status)
612		676
613	Works like perl's C<chmod> function.	677	Works like perl's C<chmod> function.
614		678
615		679
…		…
652		716
653		717
654	=item aio_realpath $pathname, $callback->($path)	718	=item aio_realpath $pathname, $callback->($path)
655		719
656	Asynchronously make the path absolute and resolve any symlinks in	720	Asynchronously make the path absolute and resolve any symlinks in
657	C<$path>. The resulting path only consists of directories (Same as	721	C<$path>. The resulting path only consists of directories (same as
658	L<Cwd::realpath>).	722	L<Cwd::realpath>).
659		723
660	This request can be used to get the absolute path of the current working	724	This request can be used to get the absolute path of the current working
661	directory by passing it a path of F<.> (a single dot).	725	directory by passing it a path of F<.> (a single dot).
662		726
663		727
664	=item aio_rename $srcpath, $dstpath, $callback->($status)	728	=item aio_rename $srcpath, $dstpath, $callback->($status)
665		729
666	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	730	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
667	rename(2) and call the callback with the result code.	731	rename(2) and call the callback with the result code.
		732
		733	On systems that support the AIO::WD working directory abstraction
		734	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		735	of failing, C<rename> is called on the absolute path of C<$wd>.
		736
		737
		738	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		739
		740	Basically a version of C<aio_rename> with an additional C<$flags>
		741	argument. Calling this with C<$flags=0> is the same as calling
		742	C<aio_rename>.
		743
		744	Non-zero flags are currently only supported on GNU/Linux systems that
		745	support renameat2. Other systems fail with C<ENOSYS> in this case.
		746
		747	The following constants are available (missing ones are, as usual C<0>),
		748	see renameat2(2) for details:
		749
		750	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		751	and C<IO::AIO::RENAME_WHITEOUT>.
668		752
669		753
670	=item aio_mkdir $pathname, $mode, $callback->($status)	754	=item aio_mkdir $pathname, $mode, $callback->($status)
671		755
672	Asynchronously mkdir (create) a directory and call the callback with	756	Asynchronously mkdir (create) a directory and call the callback with
…		…
676		760
677	=item aio_rmdir $pathname, $callback->($status)	761	=item aio_rmdir $pathname, $callback->($status)
678		762
679	Asynchronously rmdir (delete) a directory and call the callback with the	763	Asynchronously rmdir (delete) a directory and call the callback with the
680	result code.	764	result code.
		765
		766	On systems that support the AIO::WD working directory abstraction
		767	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		768	C<rmdir> is called on the absolute path of C<$wd>.
681		769
682		770
683	=item aio_readdir $pathname, $callback->($entries)	771	=item aio_readdir $pathname, $callback->($entries)
684		772
685	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	773	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
…		…
754	C<$type>'s are known, which can be used to speed up some algorithms.	842	C<$type>'s are known, which can be used to speed up some algorithms.
755		843
756	=back	844	=back
757		845
758		846
		847	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		848
		849	Opens, reads and closes the given file. The data is put into C<$data>,
		850	which is resized as required.
		851
		852	If C<$offset> is negative, then it is counted from the end of the file.
		853
		854	If C<$length> is zero, then the remaining length of the file is
		855	used. Also, in this case, the same limitations to modifying C<$data> apply
		856	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		857	with C<substr>. If the size of the file is known, specifying a non-zero
		858	C<$length> results in a performance advantage.
		859
		860	This request is similar to the older C<aio_load> request, but since it is
		861	a single request, it might be more efficient to use.
		862
		863	Example: load F</etc/passwd> into C<$passwd>.
		864
		865	my $passwd;
		866	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		867	$_[0] >= 0
		868	or die "/etc/passwd: $!\n";
		869
		870	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		871	print $passwd;
		872	};
		873	IO::AIO::flush;
		874
		875
759	=item aio_load $pathname, $data, $callback->($status)	876	=item aio_load $pathname, $data, $callback->($status)
760		877
761	This is a composite request that tries to fully load the given file into	878	This is a composite request that tries to fully load the given file into
762	memory. Status is the same as with aio_read.	879	memory. Status is the same as with aio_read.
		880
		881	Using C<aio_slurp> might be more efficient, as it is a single request.
763		882
764	=cut	883	=cut
765		884
766	sub aio_load($$;$) {	885	sub aio_load($$;$) {
767	my ($path, undef, $cb) = @_;	886	my ($path, undef, $cb) = @_;
…		…
787	=item aio_copy $srcpath, $dstpath, $callback->($status)	906	=item aio_copy $srcpath, $dstpath, $callback->($status)
788		907
789	Try to copy the I<file> (directories not supported as either source or	908	Try to copy the I<file> (directories not supported as either source or
790	destination) from C<$srcpath> to C<$dstpath> and call the callback with	909	destination) from C<$srcpath> to C<$dstpath> and call the callback with
791	a status of C<0> (ok) or C<-1> (error, see C<$!>).	910	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		911
		912	Existing destination files will be truncated.
792		913
793	This is a composite request that creates the destination file with	914	This is a composite request that creates the destination file with
794	mode 0200 and copies the contents of the source file into it using	915	mode 0200 and copies the contents of the source file into it using
795	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	916	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
796	uid/gid, in that order.	917	uid/gid, in that order.
…		…
906	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1027	Scans a directory (similar to C<aio_readdir>) but additionally tries to
907	efficiently separate the entries of directory C<$path> into two sets of	1028	efficiently separate the entries of directory C<$path> into two sets of
908	names, directories you can recurse into (directories), and ones you cannot	1029	names, directories you can recurse into (directories), and ones you cannot
909	recurse into (everything else, including symlinks to directories).	1030	recurse into (everything else, including symlinks to directories).
910		1031
911	C<aio_scandir> is a composite request that creates of many sub requests_	1032	C<aio_scandir> is a composite request that generates many sub requests.
912	C<$maxreq> specifies the maximum number of outstanding aio requests that	1033	C<$maxreq> specifies the maximum number of outstanding aio requests that
913	this function generates. If it is C<< <= 0 >>, then a suitable default	1034	this function generates. If it is C<< <= 0 >>, then a suitable default
914	will be chosen (currently 4).	1035	will be chosen (currently 4).
915		1036
916	On error, the callback is called without arguments, otherwise it receives	1037	On error, the callback is called without arguments, otherwise it receives
…		…
967	my $grp = aio_group $cb;	1088	my $grp = aio_group $cb;
968		1089
969	$maxreq = 4 if $maxreq <= 0;	1090	$maxreq = 4 if $maxreq <= 0;
970		1091
971	# get a wd object	1092	# get a wd object
972
973	aioreq_pri $pri;	1093	aioreq_pri $pri;
974	add $grp aio_wd $path, sub {	1094	add $grp aio_wd $path, sub {
		1095	$_[0]
		1096	or return $grp->result ();
		1097
975	my $wd = [shift, "."];	1098	my $wd = [shift, "."];
976		1099
977	# stat once	1100	# stat once
978	aioreq_pri $pri;	1101	aioreq_pri $pri;
979	add $grp aio_stat $wd, sub {	1102	add $grp aio_stat $wd, sub {
…		…
1048	}	1171	}
1049		1172
1050	=item aio_rmtree $pathname, $callback->($status)	1173	=item aio_rmtree $pathname, $callback->($status)
1051		1174
1052	Delete a directory tree starting (and including) C<$path>, return the	1175	Delete a directory tree starting (and including) C<$path>, return the
1053	status of the final C<rmdir> only. This is a composite request that	1176	status of the final C<rmdir> only. This is a composite request that
1054	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1177	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1055	everything else.	1178	everything else.
1056		1179
1057	=cut	1180	=cut
1058		1181
…		…
1079	add $grp $dirgrp;	1202	add $grp $dirgrp;
1080	};	1203	};
1081		1204
1082	$grp	1205	$grp
1083	}	1206	}
		1207
		1208	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1209
		1210	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1211
		1212	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1213	they execute asynchronously and pass the return value to the callback.
		1214
		1215	Both calls can be used for a lot of things, some of which make more sense
		1216	to run asynchronously in their own thread, while some others make less
		1217	sense. For example, calls that block waiting for external events, such
		1218	as locking, will also lock down an I/O thread while it is waiting, which
		1219	can deadlock the whole I/O system. At the same time, there might be no
		1220	alternative to using a thread to wait.
		1221
		1222	So in general, you should only use these calls for things that do
		1223	(filesystem) I/O, not for things that wait for other events (network,
		1224	other processes), although if you are careful and know what you are doing,
		1225	you still can.
		1226
		1227	The following constants are available (missing ones are, as usual C<0>):
		1228
		1229	C<F_DUPFD_CLOEXEC>,
		1230
		1231	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1232
		1233	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1234
		1235	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1236	C<FS_IOC_FIEMAP>.
		1237
		1238	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1239	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1240
		1241	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1242	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1243	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1244	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1245	C<FS_FL_USER_MODIFIABLE>.
		1246
		1247	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1248	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1249	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1250	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1084		1251
1085	=item aio_sync $callback->($status)	1252	=item aio_sync $callback->($status)
1086		1253
1087	Asynchronously call sync and call the callback when finished.	1254	Asynchronously call sync and call the callback when finished.
1088		1255
…		…
1157	};	1324	};
1158		1325
1159	$grp	1326	$grp
1160	}	1327	}
1161		1328
1162	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1329	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1163		1330
1164	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1331	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1165	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1332	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1166	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1333	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1167	scalar must only be modified in-place while an aio operation is pending on	1334	scalar must only be modified in-place while an aio operation is pending on
…		…
1169		1336
1170	It calls the C<msync> function of your OS, if available, with the memory	1337	It calls the C<msync> function of your OS, if available, with the memory
1171	area starting at C<$offset> in the string and ending C<$length> bytes	1338	area starting at C<$offset> in the string and ending C<$length> bytes
1172	later. If C<$length> is negative, counts from the end, and if C<$length>	1339	later. If C<$length> is negative, counts from the end, and if C<$length>
1173	is C<undef>, then it goes till the end of the string. The flags can be	1340	is C<undef>, then it goes till the end of the string. The flags can be
1174	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1341	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1175	C<IO::AIO::MS_SYNC>.	1342	C<IO::AIO::MS_INVALIDATE>.
1176		1343
1177	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1344	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1178		1345
1179	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1346	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1180	scalars.	1347	scalars.
1181		1348
1182	It touches (reads or writes) all memory pages in the specified	1349	It touches (reads or writes) all memory pages in the specified
1183	range inside the scalar. All caveats and parameters are the same	1350	range inside the scalar. All caveats and parameters are the same
1184	as for C<aio_msync>, above, except for flags, which must be either	1351	as for C<aio_msync>, above, except for flags, which must be either
1185	C<0> (which reads all pages and ensures they are instantiated) or	1352	C<0> (which reads all pages and ensures they are instantiated) or
1186	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1353	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1187	writing an octet from it, which dirties the page).	1354	writing an octet from it, which dirties the page).
1188		1355
1189	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1356	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1190		1357
1191	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1358	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1222	documented under L<MISCELLANEOUS FUNCTIONS>.	1389	documented under L<MISCELLANEOUS FUNCTIONS>.
1223		1390
1224	Example: asynchronously lock all current and future pages into memory.	1391	Example: asynchronously lock all current and future pages into memory.
1225		1392
1226	aio_mlockall IO::AIO::MCL_FUTURE;	1393	aio_mlockall IO::AIO::MCL_FUTURE;
		1394
		1395	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1396
		1397	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1398	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1399	the ioctl is not available on your OS, then this request will fail with
		1400	C<ENOSYS>.
		1401
		1402	C<$start> is the starting offset to query extents for, C<$length> is the
		1403	size of the range to query - if it is C<undef>, then the whole file will
		1404	be queried.
		1405
		1406	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1407	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1408	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1409	the data portion.
		1410
		1411	C<$count> is the maximum number of extent records to return. If it is
		1412	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1413	case, if it is C<0>, then the callback receives the number of extents
		1414	instead of the extents themselves (which is unreliable, see below).
		1415
		1416	If an error occurs, the callback receives no arguments. The special
		1417	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1418
		1419	Otherwise, the callback receives an array reference with extent
		1420	structures. Each extent structure is an array reference itself, with the
		1421	following members:
		1422
		1423	[$logical, $physical, $length, $flags]
		1424
		1425	Flags is any combination of the following flag values (typically either C<0>
		1426	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1427
		1428	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1429	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1430	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1431	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1432	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1433	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1434
		1435	At the time of this writing (Linux 3.2), this request is unreliable unless
		1436	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1437	it to return all extents of a range for files with a large number of
		1438	extents. The code (only) works around all these issues if C<$count> is
		1439	C<undef>.
1227		1440
1228	=item aio_group $callback->(...)	1441	=item aio_group $callback->(...)
1229		1442
1230	This is a very special aio request: Instead of doing something, it is a	1443	This is a very special aio request: Instead of doing something, it is a
1231	container for other aio requests, which is useful if you want to bundle	1444	container for other aio requests, which is useful if you want to bundle
…		…
1295	object. This object stores the canonicalised, absolute version of the	1508	object. This object stores the canonicalised, absolute version of the
1296	path, and on systems that allow it, also a directory file descriptor.	1509	path, and on systems that allow it, also a directory file descriptor.
1297		1510
1298	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>	1511	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1299	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD	1512	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1300	object and a pathname instead. If the pathname is absolute, the	1513	object and a pathname instead (or the IO::AIO::WD object alone, which
		1514	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1301	IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative	1515	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1302	to that IO::AIO::WD object.	1516	to that IO::AIO::WD object.
1303		1517
1304	For example, to get a wd object for F</etc> and then stat F<passwd>	1518	For example, to get a wd object for F</etc> and then stat F<passwd>
1305	inside, you would write:	1519	inside, you would write:
1306		1520
…		…
1314	aio_stat [$etcdir, "passwd"], sub {	1528	aio_stat [$etcdir, "passwd"], sub {
1315	# yay	1529	# yay
1316	};	1530	};
1317	};	1531	};
1318		1532
		1533	The fact that C<aio_wd> is a request and not a normal function shows that
1319	This shows that creating an IO::AIO::WD object is itself a potentially	1534	creating an IO::AIO::WD object is itself a potentially blocking operation,
1320	blocking operation, which is why it is done asynchronously.	1535	which is why it is done asynchronously.
		1536
		1537	To stat the directory obtained with C<aio_wd> above, one could write
		1538	either of the following three request calls:
		1539
		1540	aio_lstat "/etc" , sub { ... # pathname as normal string
		1541	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1542	aio_lstat $wd , sub { ... # shorthand for the previous
1321		1543
1322	As with normal pathnames, IO::AIO keeps a copy of the working directory	1544	As with normal pathnames, IO::AIO keeps a copy of the working directory
1323	object and the pathname string, so you could write the following without	1545	object and the pathname string, so you could write the following without
1324	causing any issues due to C<$path> getting reused:	1546	causing any issues due to C<$path> getting reused:
1325		1547
…		…
1335	There are some caveats: when directories get renamed (or deleted), the	1557	There are some caveats: when directories get renamed (or deleted), the
1336	pathname string doesn't change, so will point to the new directory (or	1558	pathname string doesn't change, so will point to the new directory (or
1337	nowhere at all), while the directory fd, if available on the system,	1559	nowhere at all), while the directory fd, if available on the system,
1338	will still point to the original directory. Most functions accepting a	1560	will still point to the original directory. Most functions accepting a
1339	pathname will use the directory fd on newer systems, and the string on	1561	pathname will use the directory fd on newer systems, and the string on
1340	older systems. Some functions (such as realpath) will always rely on the	1562	older systems. Some functions (such as C<aio_realpath>) will always rely on
1341	string form of the pathname.	1563	the string form of the pathname.
1342		1564
1343	So this fucntionality is mainly useful to get some protection against	1565	So this functionality is mainly useful to get some protection against
1344	C<chdir>, to easily get an absolute path out of a relative path for future	1566	C<chdir>, to easily get an absolute path out of a relative path for future
1345	reference, and to speed up doing many operations in the same directory	1567	reference, and to speed up doing many operations in the same directory
1346	(e.g. when stat'ing all files in a directory).	1568	(e.g. when stat'ing all files in a directory).
1347		1569
1348	The following functions implement this working directory abstraction:	1570	The following functions implement this working directory abstraction:
…		…
1361	passing C<undef> as working directory component of a pathname fails the	1583	passing C<undef> as working directory component of a pathname fails the
1362	request with C<ENOENT>, there is often no need for error checking in the	1584	request with C<ENOENT>, there is often no need for error checking in the
1363	C<aio_wd> callback, as future requests using the value will fail in the	1585	C<aio_wd> callback, as future requests using the value will fail in the
1364	expected way.	1586	expected way.
1365		1587
1366	If this call isn't available because your OS lacks it or it couldn't be
1367	detected, it will be emulated by calling C<fsync> instead.
1368
1369	=item IO::AIO::CWD	1588	=item IO::AIO::CWD
1370		1589
1371	This is a compiletime constant (object) that represents the process	1590	This is a compiletime constant (object) that represents the process
1372	current working directory.	1591	current working directory.
1373		1592
1374	Specifying this object as working directory object for a pathname is as	1593	Specifying this object as working directory object for a pathname is as if
1375	if the pathname would be specified directly, without a directory object,	1594	the pathname would be specified directly, without a directory object. For
1376	e.g., these calls are functionally identical:	1595	example, these calls are functionally identical:
1377		1596
1378	aio_stat "somefile", sub { ... };	1597	aio_stat "somefile", sub { ... };
1379	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1598	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1380		1599
1381	=back	1600	=back
1382		1601
		1602	To recover the path associated with an IO::AIO::WD object, you can use
		1603	C<aio_realpath>:
		1604
		1605	aio_realpath $wd, sub {
		1606	warn "path is $_[0]\n";
		1607	};
		1608
		1609	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1610	sometimes, fall back to using an absolue path.
1383		1611
1384	=head2 IO::AIO::REQ CLASS	1612	=head2 IO::AIO::REQ CLASS
1385		1613
1386	All non-aggregate C<aio_*> functions return an object of this class when	1614	All non-aggregate C<aio_*> functions return an object of this class when
1387	called in non-void context.	1615	called in non-void context.
…		…
1565		1793
1566	See C<poll_cb> for an example.	1794	See C<poll_cb> for an example.
1567		1795
1568	=item IO::AIO::poll_cb	1796	=item IO::AIO::poll_cb
1569		1797
1570	Process some outstanding events on the result pipe. You have to call	1798	Process some requests that have reached the result phase (i.e. they have
		1799	been executed but the results are not yet reported). You have to call
		1800	this "regularly" to finish outstanding requests.
		1801
1571	this regularly. Returns C<0> if all events could be processed (or there	1802	Returns C<0> if all events could be processed (or there were no
1572	were no events to process), or C<-1> if it returned earlier for whatever	1803	events to process), or C<-1> if it returned earlier for whatever
1573	reason. Returns immediately when no events are outstanding. The amount of	1804	reason. Returns immediately when no events are outstanding. The amount
1574	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1805	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1575	C<IO::AIO::max_poll_time>.	1806	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1576		1807
1577	If not all requests were processed for whatever reason, the filehandle	1808	If not all requests were processed for whatever reason, the poll file
1578	will still be ready when C<poll_cb> returns, so normally you don't have to	1809	descriptor will still be ready when C<poll_cb> returns, so normally you
1579	do anything special to have it called later.	1810	don't have to do anything special to have it called later.
1580		1811
1581	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1812	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1582	ready, it can be beneficial to call this function from loops which submit	1813	ready, it can be beneficial to call this function from loops which submit
1583	a lot of requests, to make sure the results get processed when they become	1814	a lot of requests, to make sure the results get processed when they become
1584	available and not just when the loop is finished and the event loop takes	1815	available and not just when the loop is finished and the event loop takes
…		…
1593	poll => 'r', async => 1,	1824	poll => 'r', async => 1,
1594	cb => \&IO::AIO::poll_cb);	1825	cb => \&IO::AIO::poll_cb);
1595		1826
1596	=item IO::AIO::poll_wait	1827	=item IO::AIO::poll_wait
1597		1828
1598	If there are any outstanding requests and none of them in the result	1829	Wait until either at least one request is in the result phase or no
1599	phase, wait till the result filehandle becomes ready for reading (simply	1830	requests are outstanding anymore.
1600	does a C<select> on the filehandle. This is useful if you want to	1831
1601	synchronously wait for some requests to finish).	1832	This is useful if you want to synchronously wait for some requests to
		1833	become ready, without actually handling them.
1602		1834
1603	See C<nreqs> for an example.	1835	See C<nreqs> for an example.
1604		1836
1605	=item IO::AIO::poll	1837	=item IO::AIO::poll
1606		1838
…		…
1727		1959
1728	This is a very bad function to use in interactive programs because it	1960	This is a very bad function to use in interactive programs because it
1729	blocks, and a bad way to reduce concurrency because it is inexact: Better	1961	blocks, and a bad way to reduce concurrency because it is inexact: Better
1730	use an C<aio_group> together with a feed callback.	1962	use an C<aio_group> together with a feed callback.
1731		1963
1732	It's main use is in scripts without an event loop - when you want to stat	1964	Its main use is in scripts without an event loop - when you want to stat
1733	a lot of files, you can write somehting like this:	1965	a lot of files, you can write something like this:
1734		1966
1735	IO::AIO::max_outstanding 32;	1967	IO::AIO::max_outstanding 32;
1736		1968
1737	for my $path (...) {	1969	for my $path (...) {
1738	aio_stat $path , ...;	1970	aio_stat $path , ...;
…		…
1777		2009
1778	=back	2010	=back
1779		2011
1780	=head3 MISCELLANEOUS FUNCTIONS	2012	=head3 MISCELLANEOUS FUNCTIONS
1781		2013
1782	IO::AIO implements some functions that might be useful, but are not	2014	IO::AIO implements some functions that are useful when you want to use
1783	asynchronous.	2015	some "Advanced I/O" function not available to in Perl, without going the
		2016	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2017	counterpart.
1784		2018
1785	=over 4	2019	=over 4
		2020
		2021	=item $numfd = IO::AIO::get_fdlimit
		2022
		2023	This function is I<EXPERIMENTAL> and subject to change.
		2024
		2025	Tries to find the current file descriptor limit and returns it, or
		2026	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2027	the highest valid file descriptor number.
		2028
		2029	=item IO::AIO::min_fdlimit [$numfd]
		2030
		2031	This function is I<EXPERIMENTAL> and subject to change.
		2032
		2033	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2034	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2035	is missing, it will try to set a very high limit, although this is not
		2036	recommended when you know the actual minimum that you require.
		2037
		2038	If the limit cannot be raised enough, the function makes a best-effort
		2039	attempt to increase the limit as much as possible, using various
		2040	tricks, while still failing. You can query the resulting limit using
		2041	C<IO::AIO::get_fdlimit>.
		2042
		2043	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2044	true.
1786		2045
1787	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2046	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1788		2047
1789	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2048	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1790	but is blocking (this makes most sense if you know the input data is	2049	but is blocking (this makes most sense if you know the input data is
…		…
1807	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2066	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1808		2067
1809	Simply calls the C<posix_madvise> function (see its	2068	Simply calls the C<posix_madvise> function (see its
1810	manpage for details). The following advice constants are	2069	manpage for details). The following advice constants are
1811	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2070	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1812	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2071	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2072	C<IO::AIO::MADV_DONTNEED>.
		2073
		2074	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2075	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2076	will be reduced to fit into the C<$scalar>.
1813		2077
1814	On systems that do not implement C<posix_madvise>, this function returns	2078	On systems that do not implement C<posix_madvise>, this function returns
1815	ENOSYS, otherwise the return value of C<posix_madvise>.	2079	ENOSYS, otherwise the return value of C<posix_madvise>.
1816		2080
1817	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2081	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
…		…
1819	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2083	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1820	$scalar (see its manpage for details). The following protect	2084	$scalar (see its manpage for details). The following protect
1821	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2085	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1822	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2086	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1823		2087
		2088	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2089	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2090	will be reduced to fit into the C<$scalar>.
		2091
1824	On systems that do not implement C<mprotect>, this function returns	2092	On systems that do not implement C<mprotect>, this function returns
1825	ENOSYS, otherwise the return value of C<mprotect>.	2093	ENOSYS, otherwise the return value of C<mprotect>.
1826		2094
1827	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2095	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1828		2096
1829	Memory-maps a file (or anonymous memory range) and attaches it to the	2097	Memory-maps a file (or anonymous memory range) and attaches it to the
1830	given C<$scalar>, which will act like a string scalar.	2098	given C<$scalar>, which will act like a string scalar. Returns true on
		2099	success, and false otherwise.
1831		2100
		2101	The scalar must exist, but its contents do not matter - this means you
		2102	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2103	the scalar first.
		2104
1832	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2105	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1833	change the string length, and most read-only operations such as copying it	2106	which don't change the string length, and most read-only operations such
1834	or searching it with regexes and so on.	2107	as copying it or searching it with regexes and so on.
1835		2108
1836	Anything else is unsafe and will, at best, result in memory leaks.	2109	Anything else is unsafe and will, at best, result in memory leaks.
1837		2110
1838	The memory map associated with the C<$scalar> is automatically removed	2111	The memory map associated with the C<$scalar> is automatically removed
1839	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2112	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1840	C<IO::AIO::munmap> functions are called.	2113	or C<IO::AIO::munmap> functions are called on it.
1841		2114
1842	This calls the C<mmap>(2) function internally. See your system's manual	2115	This calls the C<mmap>(2) function internally. See your system's manual
1843	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2116	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1844		2117
1845	The C<$length> must be larger than zero and smaller than the actual	2118	The C<$length> must be larger than zero and smaller than the actual
1846	filesize.	2119	filesize.
1847		2120
1848	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2121	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1849	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2122	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1850		2123
1851	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2124	C<$flags> can be a combination of
1852	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2125	C<IO::AIO::MAP_SHARED> or
1853	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2126	C<IO::AIO::MAP_PRIVATE>,
		2127	or a number of system-specific flags (when not available, the are C<0>):
1854	(which is set to C<MAP_ANON> if your system only provides this	2128	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1855	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2129	C<IO::AIO::MAP_LOCKED>,
1856	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2130	C<IO::AIO::MAP_NORESERVE>,
		2131	C<IO::AIO::MAP_POPULATE>,
1857	C<IO::AIO::MAP_NONBLOCK>	2132	C<IO::AIO::MAP_NONBLOCK>,
		2133	C<IO::AIO::MAP_FIXED>,
		2134	C<IO::AIO::MAP_GROWSDOWN>,
		2135	C<IO::AIO::MAP_32BIT>,
		2136	C<IO::AIO::MAP_HUGETLB> or
		2137	C<IO::AIO::MAP_STACK>.
1858		2138
1859	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2139	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1860		2140
1861	C<$offset> is the offset from the start of the file - it generally must be	2141	C<$offset> is the offset from the start of the file - it generally must be
1862	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2142	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1887		2167
1888	Calls the C<munlockall> function.	2168	Calls the C<munlockall> function.
1889		2169
1890	On systems that do not implement C<munlockall>, this function returns	2170	On systems that do not implement C<munlockall>, this function returns
1891	ENOSYS, otherwise the return value of C<munlockall>.	2171	ENOSYS, otherwise the return value of C<munlockall>.
		2172
		2173	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2174
		2175	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2176	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2177	should be the file offset.
		2178
		2179	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2180	silently corrupt the data in this case.
		2181
		2182	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2183	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2184	C<IO::AIO::SPLICE_F_GIFT>.
		2185
		2186	See the C<splice(2)> manpage for details.
		2187
		2188	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2189
		2190	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2191	description for C<IO::AIO::splice> above for details.
		2192
		2193	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2194
		2195	Attempts to query or change the pipe buffer size. Obviously works only
		2196	on pipes, and currently works only on GNU/Linux systems, and fails with
		2197	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2198	size on other systems, drop me a note.
		2199
		2200	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2201
		2202	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2203	C<$flags> is missing or C<0>, then this should be the same as a call to
		2204	perl's built-in C<pipe> function and create a new pipe, and works on
		2205	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2206	(..., 4096, O_BINARY)>.
		2207
		2208	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2209	the given flags (Linux 2.6.27, glibc 2.9).
		2210
		2211	On success, the read and write file handles are returned.
		2212
		2213	On error, nothing will be returned. If the pipe2 syscall is missing and
		2214	C<$flags> is non-zero, fails with C<ENOSYS>.
		2215
		2216	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2217	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2218	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2219
		2220	Example: create a pipe race-free w.r.t. threads and fork:
		2221
		2222	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2223	or die "pipe2: $!\n";
		2224
		2225	=item $fh = IO::AIO::eventfd ([$initval, [$flags]])
		2226
		2227	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2228	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2229
		2230	On success, the new eventfd filehandle is returned, otherwise returns
		2231	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2232
		2233	Please refer to L<eventfd(2)> for more info on this call.
		2234
		2235	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2236	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
1892		2237
1893	=back	2238	=back
1894		2239
1895	=cut	2240	=cut
1896		2241

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.211 by root, Tue Sep 27 12:10:29 2011 UTC vs.
Revision 1.281 by root, Tue Feb 20 04:32:59 2018 UTC