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Revision 1.93 by root, Wed Nov 8 01:59:58 2006 UTC vs.
Revision 1.270 by root, Fri Jun 23 03:23:19 2017 UTC

1=head1 NAME 1=head1 NAME
2 2
3IO::AIO - Asynchronous Input/Output 3IO::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
9 aio_open "/etc/passwd", O_RDONLY, 0, sub { 9 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10 my ($fh) = @_; 10 my $fh = shift
11 or die "/etc/passwd: $!";
11 ... 12 ...
12 }; 13 };
13 14
14 aio_unlink "/tmp/file", sub { }; 15 aio_unlink "/tmp/file", sub { };
15 16
25 $req->cancel; # cancel request if still in queue 26 $req->cancel; # cancel request if still in queue
26 27
27 my $grp = aio_group sub { print "all stats done\n" }; 28 my $grp = aio_group sub { print "all stats done\n" };
28 add $grp aio_stat "..." for ...; 29 add $grp aio_stat "..." for ...;
29 30
30 # AnyEvent integration
31 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
32 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33
34 # Event integration
35 Event->io (fd => IO::AIO::poll_fileno,
36 poll => 'r',
37 cb => \&IO::AIO::poll_cb);
38
39 # Glib/Gtk2 integration
40 add_watch Glib::IO IO::AIO::poll_fileno,
41 in => sub { IO::AIO::poll_cb; 1 };
42
43 # Tk integration
44 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
45 readable => \&IO::AIO::poll_cb);
46
47 # Danga::Socket integration
48 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
49 \&IO::AIO::poll_cb);
50
51=head1 DESCRIPTION 31=head1 DESCRIPTION
52 32
53This module implements asynchronous I/O using whatever means your 33This module implements asynchronous I/O using whatever means your
54operating system supports. 34operating system supports. It is implemented as an interface to C<libeio>
35(L<http://software.schmorp.de/pkg/libeio.html>).
55 36
56Asynchronous means that operations that can normally block your program 37Asynchronous means that operations that can normally block your program
57(e.g. reading from disk) will be done asynchronously: the operation 38(e.g. reading from disk) will be done asynchronously: the operation
58will still block, but you can do something else in the meantime. This 39will still block, but you can do something else in the meantime. This
59is extremely useful for programs that need to stay interactive even 40is extremely useful for programs that need to stay interactive even
61etc.), but can also be used to easily do operations in parallel that are 42etc.), but can also be used to easily do operations in parallel that are
62normally done sequentially, e.g. stat'ing many files, which is much faster 43normally done sequentially, e.g. stat'ing many files, which is much faster
63on a RAID volume or over NFS when you do a number of stat operations 44on a RAID volume or over NFS when you do a number of stat operations
64concurrently. 45concurrently.
65 46
66While most of this works on all types of file descriptors (for example 47While most of this works on all types of file descriptors (for
67sockets), using these functions on file descriptors that support 48example sockets), using these functions on file descriptors that
68nonblocking operation (again, sockets, pipes etc.) is very inefficient or 49support nonblocking operation (again, sockets, pipes etc.) is
69might not work (aio_read fails on sockets/pipes/fifos). Use an event loop 50very inefficient. Use an event loop for that (such as the L<EV>
70for that (such as the L<Event|Event> module): IO::AIO will naturally fit 51module): IO::AIO will naturally fit into such an event loop itself.
71into such an event loop itself.
72 52
73In this version, a number of threads are started that execute your 53In this version, a number of threads are started that execute your
74requests and signal their completion. You don't need thread support 54requests and signal their completion. You don't need thread support
75in perl, and the threads created by this module will not be visible 55in perl, and the threads created by this module will not be visible
76to perl. In the future, this module might make use of the native aio 56to perl. In the future, this module might make use of the native aio
78not well-supported or restricted (GNU/Linux doesn't allow them on normal 58not well-supported or restricted (GNU/Linux doesn't allow them on normal
79files currently, for example), and they would only support aio_read and 59files currently, for example), and they would only support aio_read and
80aio_write, so the remaining functionality would have to be implemented 60aio_write, so the remaining functionality would have to be implemented
81using threads anyway. 61using threads anyway.
82 62
63In addition to asynchronous I/O, this module also exports some rather
64arcane interfaces, such as C<madvise> or linux's C<splice> system call,
65which is why the C<A> in C<AIO> can also mean I<advanced>.
66
83Although the module will work with in the presence of other (Perl-) 67Although the module will work in the presence of other (Perl-) threads,
84threads, it is currently not reentrant in any way, so use appropriate 68it is currently not reentrant in any way, so use appropriate locking
85locking yourself, always call C<poll_cb> from within the same thread, or 69yourself, always call C<poll_cb> from within the same thread, or never
86never call C<poll_cb> (or other C<aio_> functions) recursively. 70call C<poll_cb> (or other C<aio_> functions) recursively.
87 71
88=head2 EXAMPLE 72=head2 EXAMPLE
89 73
90This is a simple example that uses the Event module and loads 74This is a simple example that uses the EV module and loads
91F</etc/passwd> asynchronously: 75F</etc/passwd> asynchronously:
92 76
93 use Fcntl;
94 use Event; 77 use EV;
95 use IO::AIO; 78 use IO::AIO;
96 79
97 # register the IO::AIO callback with Event 80 # register the IO::AIO callback with EV
98 Event->io (fd => IO::AIO::poll_fileno, 81 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
99 poll => 'r',
100 cb => \&IO::AIO::poll_cb);
101 82
102 # queue the request to open /etc/passwd 83 # queue the request to open /etc/passwd
103 aio_open "/etc/passwd", O_RDONLY, 0, sub { 84 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
104 my $fh = $_[0] 85 my $fh = shift
105 or die "error while opening: $!"; 86 or die "error while opening: $!";
106 87
107 # stat'ing filehandles is generally non-blocking 88 # stat'ing filehandles is generally non-blocking
108 my $size = -s $fh; 89 my $size = -s $fh;
109 90
117 98
118 # file contents now in $contents 99 # file contents now in $contents
119 print $contents; 100 print $contents;
120 101
121 # exit event loop and program 102 # exit event loop and program
122 Event::unloop; 103 EV::break;
123 }; 104 };
124 }; 105 };
125 106
126 # possibly queue up other requests, or open GUI windows, 107 # possibly queue up other requests, or open GUI windows,
127 # check for sockets etc. etc. 108 # check for sockets etc. etc.
128 109
129 # process events as long as there are some: 110 # process events as long as there are some:
130 Event::loop; 111 EV::run;
131 112
132=head1 REQUEST ANATOMY AND LIFETIME 113=head1 REQUEST ANATOMY AND LIFETIME
133 114
134Every C<aio_*> function creates a request. which is a C data structure not 115Every C<aio_*> function creates a request. which is a C data structure not
135directly visible to Perl. 116directly visible to Perl.
183 164
184=cut 165=cut
185 166
186package IO::AIO; 167package IO::AIO;
187 168
188no warnings; 169use Carp ();
189use strict 'vars'; 170
171use common::sense;
190 172
191use base 'Exporter'; 173use base 'Exporter';
192 174
193BEGIN { 175BEGIN {
194 our $VERSION = '2.2'; 176 our $VERSION = 4.35;
195 177
196 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 178 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
197 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 179 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
198 aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link 180 aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
199 aio_move aio_copy aio_group aio_nop aio_mknod); 181 aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
182 aio_pathsync aio_readahead aio_fiemap aio_allocate
183 aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
184 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
185 aio_chmod aio_utime aio_truncate
186 aio_msync aio_mtouch aio_mlock aio_mlockall
187 aio_statvfs
188 aio_wd);
189
200 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 190 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
201 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 191 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
202 min_parallel max_parallel max_idle 192 min_parallel max_parallel max_idle idle_timeout
203 nreqs nready npending nthreads 193 nreqs nready npending nthreads
204 max_poll_time max_poll_reqs); 194 max_poll_time max_poll_reqs
195 sendfile fadvise madvise
196 mmap munmap munlock munlockall);
197
198 push @AIO_REQ, qw(aio_busy); # not exported
205 199
206 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 200 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
207 201
208 require XSLoader; 202 require XSLoader;
209 XSLoader::load ("IO::AIO", $VERSION); 203 XSLoader::load ("IO::AIO", $VERSION);
210} 204}
211 205
212=head1 FUNCTIONS 206=head1 FUNCTIONS
213 207
214=head2 AIO REQUEST FUNCTIONS 208=head2 QUICK OVERVIEW
209
210This section simply lists the prototypes most of the functions for
211quick reference. See the following sections for function-by-function
212documentation.
213
214 aio_wd $pathname, $callback->($wd)
215 aio_open $pathname, $flags, $mode, $callback->($fh)
216 aio_close $fh, $callback->($status)
217 aio_seek $fh,$offset,$whence, $callback->($offs)
218 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
219 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
220 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
221 aio_readahead $fh,$offset,$length, $callback->($retval)
222 aio_stat $fh_or_path, $callback->($status)
223 aio_lstat $fh, $callback->($status)
224 aio_statvfs $fh_or_path, $callback->($statvfs)
225 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
226 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
227 aio_chmod $fh_or_path, $mode, $callback->($status)
228 aio_truncate $fh_or_path, $offset, $callback->($status)
229 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
230 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
231 aio_unlink $pathname, $callback->($status)
232 aio_mknod $pathname, $mode, $dev, $callback->($status)
233 aio_link $srcpath, $dstpath, $callback->($status)
234 aio_symlink $srcpath, $dstpath, $callback->($status)
235 aio_readlink $pathname, $callback->($link)
236 aio_realpath $pathname, $callback->($path)
237 aio_rename $srcpath, $dstpath, $callback->($status)
238 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
239 aio_mkdir $pathname, $mode, $callback->($status)
240 aio_rmdir $pathname, $callback->($status)
241 aio_readdir $pathname, $callback->($entries)
242 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
243 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
244 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
245 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
246 aio_load $pathname, $data, $callback->($status)
247 aio_copy $srcpath, $dstpath, $callback->($status)
248 aio_move $srcpath, $dstpath, $callback->($status)
249 aio_rmtree $pathname, $callback->($status)
250 aio_fcntl $fh, $cmd, $arg, $callback->($status)
251 aio_ioctl $fh, $request, $buf, $callback->($status)
252 aio_sync $callback->($status)
253 aio_syncfs $fh, $callback->($status)
254 aio_fsync $fh, $callback->($status)
255 aio_fdatasync $fh, $callback->($status)
256 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
257 aio_pathsync $pathname, $callback->($status)
258 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
259 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
260 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
261 aio_mlockall $flags, $callback->($status)
262 aio_group $callback->(...)
263 aio_nop $callback->()
264
265 $prev_pri = aioreq_pri [$pri]
266 aioreq_nice $pri_adjust
267
268 IO::AIO::poll_wait
269 IO::AIO::poll_cb
270 IO::AIO::poll
271 IO::AIO::flush
272 IO::AIO::max_poll_reqs $nreqs
273 IO::AIO::max_poll_time $seconds
274 IO::AIO::min_parallel $nthreads
275 IO::AIO::max_parallel $nthreads
276 IO::AIO::max_idle $nthreads
277 IO::AIO::idle_timeout $seconds
278 IO::AIO::max_outstanding $maxreqs
279 IO::AIO::nreqs
280 IO::AIO::nready
281 IO::AIO::npending
282
283 IO::AIO::sendfile $ofh, $ifh, $offset, $count
284 IO::AIO::fadvise $fh, $offset, $len, $advice
285 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
286 IO::AIO::munmap $scalar
287 IO::AIO::madvise $scalar, $offset, $length, $advice
288 IO::AIO::mprotect $scalar, $offset, $length, $protect
289 IO::AIO::munlock $scalar, $offset = 0, $length = undef
290 IO::AIO::munlockall
291
292=head2 API NOTES
215 293
216All the C<aio_*> calls are more or less thin wrappers around the syscall 294All the C<aio_*> calls are more or less thin wrappers around the syscall
217with the same name (sans C<aio_>). The arguments are similar or identical, 295with the same name (sans C<aio_>). The arguments are similar or identical,
218and they all accept an additional (and optional) C<$callback> argument 296and they all accept an additional (and optional) C<$callback> argument
219which must be a code reference. This code reference will get called with 297which must be a code reference. This code reference will be called after
220the syscall return code (e.g. most syscalls return C<-1> on error, unlike 298the syscall has been executed in an asynchronous fashion. The results
221perl, which usually delivers "false") as it's sole argument when the given 299of the request will be passed as arguments to the callback (and, if an
222syscall has been executed asynchronously. 300error occured, in C<$!>) - for most requests the syscall return code (e.g.
301most syscalls return C<-1> on error, unlike perl, which usually delivers
302"false").
303
304Some requests (such as C<aio_readdir>) pass the actual results and
305communicate failures by passing C<undef>.
223 306
224All functions expecting a filehandle keep a copy of the filehandle 307All functions expecting a filehandle keep a copy of the filehandle
225internally until the request has finished. 308internally until the request has finished.
226 309
227All functions return request objects of type L<IO::AIO::REQ> that allow 310All functions return request objects of type L<IO::AIO::REQ> that allow
228further manipulation of those requests while they are in-flight. 311further manipulation of those requests while they are in-flight.
229 312
230The pathnames you pass to these routines I<must> be absolute and 313The pathnames you pass to these routines I<should> be absolute. The
231encoded as octets. The reason for the former is that at the time the 314reason for this is that at the time the request is being executed, the
232request is being executed, the current working directory could have 315current working directory could have changed. Alternatively, you can
233changed. Alternatively, you can make sure that you never change the 316make sure that you never change the current working directory anywhere
234current working directory anywhere in the program and then use relative 317in the program and then use relative paths. You can also take advantage
235paths. 318of IO::AIOs working directory abstraction, that lets you specify paths
319relative to some previously-opened "working directory object" - see the
320description of the C<IO::AIO::WD> class later in this document.
236 321
237To encode pathnames as octets, either make sure you either: a) always pass 322To encode pathnames as octets, either make sure you either: a) always pass
238in filenames you got from outside (command line, readdir etc.) without 323in filenames you got from outside (command line, readdir etc.) without
239tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 324tinkering, b) are in your native filesystem encoding, c) use the Encode
240your pathnames to the locale (or other) encoding in effect in the user 325module and encode your pathnames to the locale (or other) encoding in
241environment, d) use Glib::filename_from_unicode on unicode filenames or e) 326effect in the user environment, d) use Glib::filename_from_unicode on
242use something else to ensure your scalar has the correct contents. 327unicode filenames or e) use something else to ensure your scalar has the
328correct contents.
243 329
244This works, btw. independent of the internal UTF-8 bit, which IO::AIO 330This works, btw. independent of the internal UTF-8 bit, which IO::AIO
245handles correctly wether it is set or not. 331handles correctly whether it is set or not.
332
333=head2 AIO REQUEST FUNCTIONS
246 334
247=over 4 335=over 4
248 336
249=item $prev_pri = aioreq_pri [$pri] 337=item $prev_pri = aioreq_pri [$pri]
250 338
270 aio_read $_[0], ..., sub { 358 aio_read $_[0], ..., sub {
271 ... 359 ...
272 }; 360 };
273 }; 361 };
274 362
363
275=item aioreq_nice $pri_adjust 364=item aioreq_nice $pri_adjust
276 365
277Similar to C<aioreq_pri>, but subtracts the given value from the current 366Similar to C<aioreq_pri>, but subtracts the given value from the current
278priority, so the effect is cumulative. 367priority, so the effect is cumulative.
279 368
369
280=item aio_open $pathname, $flags, $mode, $callback->($fh) 370=item aio_open $pathname, $flags, $mode, $callback->($fh)
281 371
282Asynchronously open or create a file and call the callback with a newly 372Asynchronously open or create a file and call the callback with a newly
283created filehandle for the file. 373created filehandle for the file (or C<undef> in case of an error).
284 374
285The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 375The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
286for an explanation. 376for an explanation.
287 377
288The C<$flags> argument is a bitmask. See the C<Fcntl> module for a 378The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
289list. They are the same as used by C<sysopen>. 379list. They are the same as used by C<sysopen>.
290 380
291Likewise, C<$mode> specifies the mode of the newly created file, if it 381Likewise, C<$mode> specifies the mode of the newly created file, if it
292didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, 382didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
293except that it is mandatory (i.e. use C<0> if you don't create new files, 383except that it is mandatory (i.e. use C<0> if you don't create new files,
294and C<0666> or C<0777> if you do). 384and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
385by the umask in effect then the request is being executed, so better never
386change the umask.
295 387
296Example: 388Example:
297 389
298 aio_open "/etc/passwd", O_RDONLY, 0, sub { 390 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
299 if ($_[0]) { 391 if ($_[0]) {
300 print "open successful, fh is $_[0]\n"; 392 print "open successful, fh is $_[0]\n";
301 ... 393 ...
302 } else { 394 } else {
303 die "open failed: $!\n"; 395 die "open failed: $!\n";
304 } 396 }
305 }; 397 };
306 398
399In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
400C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
401following POSIX and non-POSIX constants are available (missing ones on
402your system are, as usual, C<0>):
403
404C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
405C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
406C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
407
408
307=item aio_close $fh, $callback->($status) 409=item aio_close $fh, $callback->($status)
308 410
309Asynchronously close a file and call the callback with the result 411Asynchronously close a file and call the callback with the result
310code. I<WARNING:> although accepted, you should not pass in a perl 412code.
311filehandle here, as perl will likely close the file descriptor another
312time when the filehandle is destroyed. Normally, you can safely call perls
313C<close> or just let filehandles go out of scope.
314 413
315This is supposed to be a bug in the API, so that might change. It's 414Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
316therefore best to avoid this function. 415closing the file descriptor associated with the filehandle itself.
416
417Therefore, C<aio_close> will not close the filehandle - instead it will
418use dup2 to overwrite the file descriptor with the write-end of a pipe
419(the pipe fd will be created on demand and will be cached).
420
421Or in other words: the file descriptor will be closed, but it will not be
422free for reuse until the perl filehandle is closed.
423
424=cut
425
426=item aio_seek $fh, $offset, $whence, $callback->($offs)
427
428Seeks the filehandle to the new C<$offset>, similarly to perl's
429C<sysseek>. The C<$whence> can use the traditional values (C<0> for
430C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
431C<IO::AIO::SEEK_END>).
432
433The resulting absolute offset will be passed to the callback, or C<-1> in
434case of an error.
435
436In theory, the C<$whence> constants could be different than the
437corresponding values from L<Fcntl>, but perl guarantees they are the same,
438so don't panic.
439
440As a GNU/Linux (and maybe Solaris) extension, also the constants
441C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
442could be found. No guarantees about suitability for use in C<aio_seek> or
443Perl's C<sysseek> can be made though, although I would naively assume they
444"just work".
317 445
318=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 446=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
319 447
320=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 448=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
321 449
322Reads or writes C<length> bytes from the specified C<fh> and C<offset> 450Reads or writes C<$length> bytes from or to the specified C<$fh> and
323into the scalar given by C<data> and offset C<dataoffset> and calls the 451C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
324callback without the actual number of bytes read (or -1 on error, just 452calls the callback with the actual number of bytes transferred (or -1 on
325like the syscall). 453error, just like the syscall).
454
455C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
456offset plus the actual number of bytes read.
457
458If C<$offset> is undefined, then the current file descriptor offset will
459be used (and updated), otherwise the file descriptor offset will not be
460changed by these calls.
461
462If C<$length> is undefined in C<aio_write>, use the remaining length of
463C<$data>.
464
465If C<$dataoffset> is less than zero, it will be counted from the end of
466C<$data>.
326 467
327The C<$data> scalar I<MUST NOT> be modified in any way while the request 468The C<$data> scalar I<MUST NOT> be modified in any way while the request
328is outstanding. Modifying it can result in segfaults or WW3 (if the 469is outstanding. Modifying it can result in segfaults or World War III (if
329necessary/optional hardware is installed). 470the necessary/optional hardware is installed).
330 471
331Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 472Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
332offset C<0> within the scalar: 473offset C<0> within the scalar:
333 474
334 aio_read $fh, 7, 15, $buffer, 0, sub { 475 aio_read $fh, 7, 15, $buffer, 0, sub {
335 $_[0] > 0 or die "read error: $!"; 476 $_[0] > 0 or die "read error: $!";
336 print "read $_[0] bytes: <$buffer>\n"; 477 print "read $_[0] bytes: <$buffer>\n";
337 }; 478 };
338 479
480
339=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 481=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
340 482
341Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 483Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
342reading at byte offset C<$in_offset>, and starts writing at the current 484reading at byte offset C<$in_offset>, and starts writing at the current
343file offset of C<$out_fh>. Because of that, it is not safe to issue more 485file offset of C<$out_fh>. Because of that, it is not safe to issue more
344than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 486than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
345other. 487other. The same C<$in_fh> works fine though, as this function does not
488move or use the file offset of C<$in_fh>.
346 489
490Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
491are written, and there is no way to find out how many more bytes have been
492read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
493number of bytes written to C<$out_fh>. Only if the result value equals
494C<$length> one can assume that C<$length> bytes have been read.
495
496Unlike with other C<aio_> functions, it makes a lot of sense to use
497C<aio_sendfile> on non-blocking sockets, as long as one end (typically
498the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
499the socket I/O will be non-blocking. Note, however, that you can run
500into a trap where C<aio_sendfile> reads some data with readahead, then
501fails to write all data, and when the socket is ready the next time, the
502data in the cache is already lost, forcing C<aio_sendfile> to again hit
503the disk. Explicit C<aio_read> + C<aio_write> let's you better control
504resource usage.
505
347This call tries to make use of a native C<sendfile> syscall to provide 506This call tries to make use of a native C<sendfile>-like syscall to
348zero-copy operation. For this to work, C<$out_fh> should refer to a 507provide zero-copy operation. For this to work, C<$out_fh> should refer to
349socket, and C<$in_fh> should refer to mmap'able file. 508a socket, and C<$in_fh> should refer to an mmap'able file.
350 509
351If the native sendfile call fails or is not implemented, it will be 510If a native sendfile cannot be found or it fails with C<ENOSYS>,
352emulated, so you can call C<aio_sendfile> on any type of filehandle 511C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
512C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
353regardless of the limitations of the operating system. 513type of filehandle regardless of the limitations of the operating system.
354 514
355Please note, however, that C<aio_sendfile> can read more bytes from 515As native sendfile syscalls (as practically any non-POSIX interface hacked
356C<$in_fh> than are written, and there is no way to find out how many 516together in a hurry to improve benchmark numbers) tend to be rather buggy
357bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 517on many systems, this implementation tries to work around some known bugs
358provides the number of bytes written to C<$out_fh>. Only if the result 518in Linux and FreeBSD kernels (probably others, too), but that might fail,
359value equals C<$length> one can assume that C<$length> bytes have been 519so you really really should check the return value of C<aio_sendfile> -
360read. 520fewer bytes than expected might have been transferred.
521
361 522
362=item aio_readahead $fh,$offset,$length, $callback->($retval) 523=item aio_readahead $fh,$offset,$length, $callback->($retval)
363 524
364C<aio_readahead> populates the page cache with data from a file so that 525C<aio_readahead> populates the page cache with data from a file so that
365subsequent reads from that file will not block on disk I/O. The C<$offset> 526subsequent reads from that file will not block on disk I/O. The C<$offset>
368whole pages, so that offset is effectively rounded down to a page boundary 529whole pages, so that offset is effectively rounded down to a page boundary
369and bytes are read up to the next page boundary greater than or equal to 530and bytes are read up to the next page boundary greater than or equal to
370(off-set+length). C<aio_readahead> does not read beyond the end of the 531(off-set+length). C<aio_readahead> does not read beyond the end of the
371file. The current file offset of the file is left unchanged. 532file. The current file offset of the file is left unchanged.
372 533
373If that syscall doesn't exist (likely if your OS isn't Linux) it will be 534If that syscall doesn't exist (likely if your kernel isn't Linux) it will
374emulated by simply reading the data, which would have a similar effect. 535be emulated by simply reading the data, which would have a similar effect.
536
375 537
376=item aio_stat $fh_or_path, $callback->($status) 538=item aio_stat $fh_or_path, $callback->($status)
377 539
378=item aio_lstat $fh, $callback->($status) 540=item aio_lstat $fh, $callback->($status)
379 541
385for an explanation. 547for an explanation.
386 548
387Currently, the stats are always 64-bit-stats, i.e. instead of returning an 549Currently, the stats are always 64-bit-stats, i.e. instead of returning an
388error when stat'ing a large file, the results will be silently truncated 550error when stat'ing a large file, the results will be silently truncated
389unless perl itself is compiled with large file support. 551unless perl itself is compiled with large file support.
552
553To help interpret the mode and dev/rdev stat values, IO::AIO offers the
554following constants and functions (if not implemented, the constants will
555be C<0> and the functions will either C<croak> or fall back on traditional
556behaviour).
557
558C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
559C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
560C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
390 561
391Example: Print the length of F</etc/passwd>: 562Example: Print the length of F</etc/passwd>:
392 563
393 aio_stat "/etc/passwd", sub { 564 aio_stat "/etc/passwd", sub {
394 $_[0] and die "stat failed: $!"; 565 $_[0] and die "stat failed: $!";
395 print "size is ", -s _, "\n"; 566 print "size is ", -s _, "\n";
396 }; 567 };
397 568
569
570=item aio_statvfs $fh_or_path, $callback->($statvfs)
571
572Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
573whether a file handle or path was passed.
574
575On success, the callback is passed a hash reference with the following
576members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
577C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
578is passed.
579
580The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
581C<ST_NOSUID>.
582
583The following non-POSIX IO::AIO::ST_* flag masks are defined to
584their correct value when available, or to C<0> on systems that do
585not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
586C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
587C<ST_NODIRATIME> and C<ST_RELATIME>.
588
589Example: stat C</wd> and dump out the data if successful.
590
591 aio_statvfs "/wd", sub {
592 my $f = $_[0]
593 or die "statvfs: $!";
594
595 use Data::Dumper;
596 say Dumper $f;
597 };
598
599 # result:
600 {
601 bsize => 1024,
602 bfree => 4333064312,
603 blocks => 10253828096,
604 files => 2050765568,
605 flag => 4096,
606 favail => 2042092649,
607 bavail => 4333064312,
608 ffree => 2042092649,
609 namemax => 255,
610 frsize => 1024,
611 fsid => 1810
612 }
613
614Here is a (likely partial - send me updates!) list of fsid values used by
615Linux - it is safe to hardcode these when C<$^O> is C<linux>:
616
617 0x0000adf5 adfs
618 0x0000adff affs
619 0x5346414f afs
620 0x09041934 anon-inode filesystem
621 0x00000187 autofs
622 0x42465331 befs
623 0x1badface bfs
624 0x42494e4d binfmt_misc
625 0x9123683e btrfs
626 0x0027e0eb cgroupfs
627 0xff534d42 cifs
628 0x73757245 coda
629 0x012ff7b7 coh
630 0x28cd3d45 cramfs
631 0x453dcd28 cramfs-wend (wrong endianness)
632 0x64626720 debugfs
633 0x00001373 devfs
634 0x00001cd1 devpts
635 0x0000f15f ecryptfs
636 0x00414a53 efs
637 0x0000137d ext
638 0x0000ef53 ext2/ext3/ext4
639 0x0000ef51 ext2
640 0xf2f52010 f2fs
641 0x00004006 fat
642 0x65735546 fuseblk
643 0x65735543 fusectl
644 0x0bad1dea futexfs
645 0x01161970 gfs2
646 0x47504653 gpfs
647 0x00004244 hfs
648 0xf995e849 hpfs
649 0x00c0ffee hostfs
650 0x958458f6 hugetlbfs
651 0x2bad1dea inotifyfs
652 0x00009660 isofs
653 0x000072b6 jffs2
654 0x3153464a jfs
655 0x6b414653 k-afs
656 0x0bd00bd0 lustre
657 0x0000137f minix
658 0x0000138f minix 30 char names
659 0x00002468 minix v2
660 0x00002478 minix v2 30 char names
661 0x00004d5a minix v3
662 0x19800202 mqueue
663 0x00004d44 msdos
664 0x0000564c novell
665 0x00006969 nfs
666 0x6e667364 nfsd
667 0x00003434 nilfs
668 0x5346544e ntfs
669 0x00009fa1 openprom
670 0x7461636F ocfs2
671 0x00009fa0 proc
672 0x6165676c pstorefs
673 0x0000002f qnx4
674 0x68191122 qnx6
675 0x858458f6 ramfs
676 0x52654973 reiserfs
677 0x00007275 romfs
678 0x67596969 rpc_pipefs
679 0x73636673 securityfs
680 0xf97cff8c selinux
681 0x0000517b smb
682 0x534f434b sockfs
683 0x73717368 squashfs
684 0x62656572 sysfs
685 0x012ff7b6 sysv2
686 0x012ff7b5 sysv4
687 0x01021994 tmpfs
688 0x15013346 udf
689 0x00011954 ufs
690 0x54190100 ufs byteswapped
691 0x00009fa2 usbdevfs
692 0x01021997 v9fs
693 0xa501fcf5 vxfs
694 0xabba1974 xenfs
695 0x012ff7b4 xenix
696 0x58465342 xfs
697 0x012fd16d xia
698
699=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
700
701Works like perl's C<utime> function (including the special case of $atime
702and $mtime being undef). Fractional times are supported if the underlying
703syscalls support them.
704
705When called with a pathname, uses utimes(2) if available, otherwise
706utime(2). If called on a file descriptor, uses futimes(2) if available,
707otherwise returns ENOSYS, so this is not portable.
708
709Examples:
710
711 # set atime and mtime to current time (basically touch(1)):
712 aio_utime "path", undef, undef;
713 # set atime to current time and mtime to beginning of the epoch:
714 aio_utime "path", time, undef; # undef==0
715
716
717=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
718
719Works like perl's C<chown> function, except that C<undef> for either $uid
720or $gid is being interpreted as "do not change" (but -1 can also be used).
721
722Examples:
723
724 # same as "chown root path" in the shell:
725 aio_chown "path", 0, -1;
726 # same as above:
727 aio_chown "path", 0, undef;
728
729
730=item aio_truncate $fh_or_path, $offset, $callback->($status)
731
732Works like truncate(2) or ftruncate(2).
733
734
735=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
736
737Allocates or frees disk space according to the C<$mode> argument. See the
738linux C<fallocate> documentation for details.
739
740C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
741space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
742to deallocate a file range.
743
744IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
745(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
746your L<fallocate(2)> manpage).
747
748The file system block size used by C<fallocate> is presumably the
749C<f_bsize> returned by C<statvfs>.
750
751If C<fallocate> isn't available or cannot be emulated (currently no
752emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
753
754
755=item aio_chmod $fh_or_path, $mode, $callback->($status)
756
757Works like perl's C<chmod> function.
758
759
398=item aio_unlink $pathname, $callback->($status) 760=item aio_unlink $pathname, $callback->($status)
399 761
400Asynchronously unlink (delete) a file and call the callback with the 762Asynchronously unlink (delete) a file and call the callback with the
401result code. 763result code.
402 764
765
403=item aio_mknod $path, $mode, $dev, $callback->($status) 766=item aio_mknod $pathname, $mode, $dev, $callback->($status)
404 767
405[EXPERIMENTAL] 768[EXPERIMENTAL]
406 769
407Asynchronously create a device node (or fifo). See mknod(2). 770Asynchronously create a device node (or fifo). See mknod(2).
408 771
409The only (POSIX-) portable way of calling this function is: 772The only (POSIX-) portable way of calling this function is:
410 773
411 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 774 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
775
776See C<aio_stat> for info about some potentially helpful extra constants
777and functions.
412 778
413=item aio_link $srcpath, $dstpath, $callback->($status) 779=item aio_link $srcpath, $dstpath, $callback->($status)
414 780
415Asynchronously create a new link to the existing object at C<$srcpath> at 781Asynchronously create a new link to the existing object at C<$srcpath> at
416the path C<$dstpath> and call the callback with the result code. 782the path C<$dstpath> and call the callback with the result code.
417 783
784
418=item aio_symlink $srcpath, $dstpath, $callback->($status) 785=item aio_symlink $srcpath, $dstpath, $callback->($status)
419 786
420Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 787Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
421the path C<$dstpath> and call the callback with the result code. 788the path C<$dstpath> and call the callback with the result code.
422 789
790
423=item aio_readlink $path, $callback->($link) 791=item aio_readlink $pathname, $callback->($link)
424 792
425Asynchronously read the symlink specified by C<$path> and pass it to 793Asynchronously read the symlink specified by C<$path> and pass it to
426the callback. If an error occurs, nothing or undef gets passed to the 794the callback. If an error occurs, nothing or undef gets passed to the
427callback. 795callback.
428 796
797
798=item aio_realpath $pathname, $callback->($path)
799
800Asynchronously make the path absolute and resolve any symlinks in
801C<$path>. The resulting path only consists of directories (same as
802L<Cwd::realpath>).
803
804This request can be used to get the absolute path of the current working
805directory by passing it a path of F<.> (a single dot).
806
807
429=item aio_rename $srcpath, $dstpath, $callback->($status) 808=item aio_rename $srcpath, $dstpath, $callback->($status)
430 809
431Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 810Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
432rename(2) and call the callback with the result code. 811rename(2) and call the callback with the result code.
433 812
813On systems that support the AIO::WD working directory abstraction
814natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
815of failing, C<rename> is called on the absolute path of C<$wd>.
816
817
818=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
819
820Basically a version of C<aio_rename> with an additional C<$flags>
821argument. Calling this with C<$flags=0> is the same as calling
822C<aio_rename>.
823
824Non-zero flags are currently only supported on GNU/Linux systems that
825support renameat2. Other systems fail with C<ENOSYS> in this case.
826
827The following constants are available (missing ones are, as usual C<0>),
828see renameat2(2) for details:
829
830C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
831and C<IO::AIO::RENAME_WHITEOUT>.
832
833
834=item aio_mkdir $pathname, $mode, $callback->($status)
835
836Asynchronously mkdir (create) a directory and call the callback with
837the result code. C<$mode> will be modified by the umask at the time the
838request is executed, so do not change your umask.
839
840
434=item aio_rmdir $pathname, $callback->($status) 841=item aio_rmdir $pathname, $callback->($status)
435 842
436Asynchronously rmdir (delete) a directory and call the callback with the 843Asynchronously rmdir (delete) a directory and call the callback with the
437result code. 844result code.
845
846On systems that support the AIO::WD working directory abstraction
847natively, the case C<[$wd, "."]> is specialcased - instead of failing,
848C<rmdir> is called on the absolute path of C<$wd>.
849
438 850
439=item aio_readdir $pathname, $callback->($entries) 851=item aio_readdir $pathname, $callback->($entries)
440 852
441Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 853Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
442directory (i.e. opendir + readdir + closedir). The entries will not be 854directory (i.e. opendir + readdir + closedir). The entries will not be
443sorted, and will B<NOT> include the C<.> and C<..> entries. 855sorted, and will B<NOT> include the C<.> and C<..> entries.
444 856
445The callback a single argument which is either C<undef> or an array-ref 857The callback is passed a single argument which is either C<undef> or an
446with the filenames. 858array-ref with the filenames.
859
860
861=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
862
863Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
864tune behaviour and output format. In case of an error, C<$entries> will be
865C<undef>.
866
867The flags are a combination of the following constants, ORed together (the
868flags will also be passed to the callback, possibly modified):
869
870=over 4
871
872=item IO::AIO::READDIR_DENTS
873
874When this flag is off, then the callback gets an arrayref consisting of
875names only (as with C<aio_readdir>), otherwise it gets an arrayref with
876C<[$name, $type, $inode]> arrayrefs, each describing a single directory
877entry in more detail.
878
879C<$name> is the name of the entry.
880
881C<$type> is one of the C<IO::AIO::DT_xxx> constants:
882
883C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
884C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
885C<IO::AIO::DT_WHT>.
886
887C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
888know, you have to run stat yourself. Also, for speed reasons, the C<$type>
889scalars are read-only: you can not modify them.
890
891C<$inode> is the inode number (which might not be exact on systems with 64
892bit inode numbers and 32 bit perls). This field has unspecified content on
893systems that do not deliver the inode information.
894
895=item IO::AIO::READDIR_DIRS_FIRST
896
897When this flag is set, then the names will be returned in an order where
898likely directories come first, in optimal stat order. This is useful when
899you need to quickly find directories, or you want to find all directories
900while avoiding to stat() each entry.
901
902If the system returns type information in readdir, then this is used
903to find directories directly. Otherwise, likely directories are names
904beginning with ".", or otherwise names with no dots, of which names with
905short names are tried first.
906
907=item IO::AIO::READDIR_STAT_ORDER
908
909When this flag is set, then the names will be returned in an order
910suitable for stat()'ing each one. That is, when you plan to stat()
911all files in the given directory, then the returned order will likely
912be fastest.
913
914If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
915the likely dirs come first, resulting in a less optimal stat order.
916
917=item IO::AIO::READDIR_FOUND_UNKNOWN
918
919This flag should not be set when calling C<aio_readdirx>. Instead, it
920is being set by C<aio_readdirx>, when any of the C<$type>'s found were
921C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
922C<$type>'s are known, which can be used to speed up some algorithms.
923
924=back
925
926
927=item aio_load $pathname, $data, $callback->($status)
928
929This is a composite request that tries to fully load the given file into
930memory. Status is the same as with aio_read.
931
932=cut
933
934sub aio_load($$;$) {
935 my ($path, undef, $cb) = @_;
936 my $data = \$_[1];
937
938 my $pri = aioreq_pri;
939 my $grp = aio_group $cb;
940
941 aioreq_pri $pri;
942 add $grp aio_open $path, O_RDONLY, 0, sub {
943 my $fh = shift
944 or return $grp->result (-1);
945
946 aioreq_pri $pri;
947 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
948 $grp->result ($_[0]);
949 };
950 };
951
952 $grp
953}
447 954
448=item aio_copy $srcpath, $dstpath, $callback->($status) 955=item aio_copy $srcpath, $dstpath, $callback->($status)
449 956
450Try to copy the I<file> (directories not supported as either source or 957Try to copy the I<file> (directories not supported as either source or
451destination) from C<$srcpath> to C<$dstpath> and call the callback with 958destination) from C<$srcpath> to C<$dstpath> and call the callback with
452the C<0> (error) or C<-1> ok. 959a status of C<0> (ok) or C<-1> (error, see C<$!>).
453 960
454This is a composite request that it creates the destination file with 961This is a composite request that creates the destination file with
455mode 0200 and copies the contents of the source file into it using 962mode 0200 and copies the contents of the source file into it using
456C<aio_sendfile>, followed by restoring atime, mtime, access mode and 963C<aio_sendfile>, followed by restoring atime, mtime, access mode and
457uid/gid, in that order. 964uid/gid, in that order.
458 965
459If an error occurs, the partial destination file will be unlinked, if 966If an error occurs, the partial destination file will be unlinked, if
469 my $grp = aio_group $cb; 976 my $grp = aio_group $cb;
470 977
471 aioreq_pri $pri; 978 aioreq_pri $pri;
472 add $grp aio_open $src, O_RDONLY, 0, sub { 979 add $grp aio_open $src, O_RDONLY, 0, sub {
473 if (my $src_fh = $_[0]) { 980 if (my $src_fh = $_[0]) {
474 my @stat = stat $src_fh; 981 my @stat = stat $src_fh; # hmm, might block over nfs?
475 982
476 aioreq_pri $pri; 983 aioreq_pri $pri;
477 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { 984 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
478 if (my $dst_fh = $_[0]) { 985 if (my $dst_fh = $_[0]) {
479 aioreq_pri $pri; 986 aioreq_pri $pri;
480 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { 987 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
481 if ($_[0] == $stat[7]) { 988 if ($_[0] == $stat[7]) {
482 $grp->result (0); 989 $grp->result (0);
483 close $src_fh; 990 close $src_fh;
484 991
485 # those should not normally block. should. should. 992 my $ch = sub {
993 aioreq_pri $pri;
994 add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
995 aioreq_pri $pri;
996 add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
997 aioreq_pri $pri;
998 add $grp aio_close $dst_fh;
999 }
1000 };
1001 };
1002
1003 aioreq_pri $pri;
1004 add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
1005 if ($_[0] < 0 && $! == ENOSYS) {
1006 aioreq_pri $pri;
486 utime $stat[8], $stat[9], $dst; 1007 add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
487 chmod $stat[2] & 07777, $dst_fh; 1008 } else {
488 chown $stat[4], $stat[5], $dst_fh; 1009 $ch->();
1010 }
489 close $dst_fh; 1011 };
490 } else { 1012 } else {
491 $grp->result (-1); 1013 $grp->result (-1);
492 close $src_fh; 1014 close $src_fh;
493 close $dst_fh; 1015 close $dst_fh;
494 1016
511 1033
512=item aio_move $srcpath, $dstpath, $callback->($status) 1034=item aio_move $srcpath, $dstpath, $callback->($status)
513 1035
514Try to move the I<file> (directories not supported as either source or 1036Try to move the I<file> (directories not supported as either source or
515destination) from C<$srcpath> to C<$dstpath> and call the callback with 1037destination) from C<$srcpath> to C<$dstpath> and call the callback with
516the C<0> (error) or C<-1> ok. 1038a status of C<0> (ok) or C<-1> (error, see C<$!>).
517 1039
518This is a composite request that tries to rename(2) the file first. If 1040This is a composite request that tries to rename(2) the file first; if
519rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if 1041rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
520that is successful, unlinking the C<$srcpath>. 1042that is successful, unlinks the C<$srcpath>.
521 1043
522=cut 1044=cut
523 1045
524sub aio_move($$;$) { 1046sub aio_move($$;$) {
525 my ($src, $dst, $cb) = @_; 1047 my ($src, $dst, $cb) = @_;
532 if ($_[0] && $! == EXDEV) { 1054 if ($_[0] && $! == EXDEV) {
533 aioreq_pri $pri; 1055 aioreq_pri $pri;
534 add $grp aio_copy $src, $dst, sub { 1056 add $grp aio_copy $src, $dst, sub {
535 $grp->result ($_[0]); 1057 $grp->result ($_[0]);
536 1058
537 if (!$_[0]) { 1059 unless ($_[0]) {
538 aioreq_pri $pri; 1060 aioreq_pri $pri;
539 add $grp aio_unlink $src; 1061 add $grp aio_unlink $src;
540 } 1062 }
541 }; 1063 };
542 } else { 1064 } else {
545 }; 1067 };
546 1068
547 $grp 1069 $grp
548} 1070}
549 1071
550=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 1072=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
551 1073
552Scans a directory (similar to C<aio_readdir>) but additionally tries to 1074Scans a directory (similar to C<aio_readdir>) but additionally tries to
553efficiently separate the entries of directory C<$path> into two sets of 1075efficiently separate the entries of directory C<$path> into two sets of
554names, directories you can recurse into (directories), and ones you cannot 1076names, directories you can recurse into (directories), and ones you cannot
555recurse into (everything else, including symlinks to directories). 1077recurse into (everything else, including symlinks to directories).
572 1094
573Implementation notes. 1095Implementation notes.
574 1096
575The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. 1097The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
576 1098
1099If readdir returns file type information, then this is used directly to
1100find directories.
1101
577After reading the directory, the modification time, size etc. of the 1102Otherwise, after reading the directory, the modification time, size etc.
578directory before and after the readdir is checked, and if they match (and 1103of the directory before and after the readdir is checked, and if they
579isn't the current time), the link count will be used to decide how many 1104match (and isn't the current time), the link count will be used to decide
580entries are directories (if >= 2). Otherwise, no knowledge of the number 1105how many entries are directories (if >= 2). Otherwise, no knowledge of the
581of subdirectories will be assumed. 1106number of subdirectories will be assumed.
582 1107
583Then entries will be sorted into likely directories (everything without 1108Then entries will be sorted into likely directories a non-initial dot
584a non-initial dot currently) and likely non-directories (everything 1109currently) and likely non-directories (see C<aio_readdirx>). Then every
585else). Then every entry plus an appended C</.> will be C<stat>'ed, 1110entry plus an appended C</.> will be C<stat>'ed, likely directories first,
586likely directories first. If that succeeds, it assumes that the entry 1111in order of their inode numbers. If that succeeds, it assumes that the
587is a directory or a symlink to directory (which will be checked 1112entry is a directory or a symlink to directory (which will be checked
588seperately). This is often faster than stat'ing the entry itself because 1113separately). This is often faster than stat'ing the entry itself because
589filesystems might detect the type of the entry without reading the inode 1114filesystems might detect the type of the entry without reading the inode
590data (e.g. ext2fs filetype feature). 1115data (e.g. ext2fs filetype feature), even on systems that cannot return
1116the filetype information on readdir.
591 1117
592If the known number of directories (link count - 2) has been reached, the 1118If the known number of directories (link count - 2) has been reached, the
593rest of the entries is assumed to be non-directories. 1119rest of the entries is assumed to be non-directories.
594 1120
595This only works with certainty on POSIX (= UNIX) filesystems, which 1121This only works with certainty on POSIX (= UNIX) filesystems, which
599as those tend to return 0 or 1 as link counts, which disables the 1125as those tend to return 0 or 1 as link counts, which disables the
600directory counting heuristic. 1126directory counting heuristic.
601 1127
602=cut 1128=cut
603 1129
604sub aio_scandir($$$) { 1130sub aio_scandir($$;$) {
605 my ($path, $maxreq, $cb) = @_; 1131 my ($path, $maxreq, $cb) = @_;
606 1132
607 my $pri = aioreq_pri; 1133 my $pri = aioreq_pri;
608 1134
609 my $grp = aio_group $cb; 1135 my $grp = aio_group $cb;
610 1136
611 $maxreq = 4 if $maxreq <= 0; 1137 $maxreq = 4 if $maxreq <= 0;
612 1138
613 # stat once 1139 # get a wd object
614 aioreq_pri $pri; 1140 aioreq_pri $pri;
615 add $grp aio_stat $path, sub { 1141 add $grp aio_wd $path, sub {
1142 $_[0]
616 return $grp->result () if $_[0]; 1143 or return $grp->result ();
617 my $now = time;
618 my $hash1 = join ":", (stat _)[0,1,3,7,9];
619 1144
620 # read the directory entries 1145 my $wd = [shift, "."];
1146
1147 # stat once
621 aioreq_pri $pri; 1148 aioreq_pri $pri;
622 add $grp aio_readdir $path, sub { 1149 add $grp aio_stat $wd, sub {
623 my $entries = shift
624 or return $grp->result (); 1150 return $grp->result () if $_[0];
1151 my $now = time;
1152 my $hash1 = join ":", (stat _)[0,1,3,7,9];
625 1153
626 # stat the dir another time 1154 # read the directory entries
627 aioreq_pri $pri; 1155 aioreq_pri $pri;
1156 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
1157 my $entries = shift
1158 or return $grp->result ();
1159
1160 # stat the dir another time
1161 aioreq_pri $pri;
628 add $grp aio_stat $path, sub { 1162 add $grp aio_stat $wd, sub {
629 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1163 my $hash2 = join ":", (stat _)[0,1,3,7,9];
630 1164
631 my $ndirs; 1165 my $ndirs;
632 1166
633 # take the slow route if anything looks fishy 1167 # take the slow route if anything looks fishy
634 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1168 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
635 $ndirs = -1; 1169 $ndirs = -1;
636 } else { 1170 } else {
637 # if nlink == 2, we are finished 1171 # if nlink == 2, we are finished
638 # on non-posix-fs's, we rely on nlink < 2 1172 # for non-posix-fs's, we rely on nlink < 2
639 $ndirs = (stat _)[3] - 2 1173 $ndirs = (stat _)[3] - 2
640 or return $grp->result ([], $entries); 1174 or return $grp->result ([], $entries);
641 } 1175 }
642 1176
643 # sort into likely dirs and likely nondirs
644 # dirs == files without ".", short entries first
645 $entries = [map $_->[0],
646 sort { $b->[1] cmp $a->[1] }
647 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
648 @$entries];
649
650 my (@dirs, @nondirs); 1177 my (@dirs, @nondirs);
651 1178
652 my $statgrp = add $grp aio_group sub { 1179 my $statgrp = add $grp aio_group sub {
653 $grp->result (\@dirs, \@nondirs); 1180 $grp->result (\@dirs, \@nondirs);
654 }; 1181 };
655 1182
656 limit $statgrp $maxreq; 1183 limit $statgrp $maxreq;
657 feed $statgrp sub { 1184 feed $statgrp sub {
658 return unless @$entries; 1185 return unless @$entries;
659 my $entry = pop @$entries; 1186 my $entry = shift @$entries;
660 1187
661 aioreq_pri $pri; 1188 aioreq_pri $pri;
1189 $wd->[1] = "$entry/.";
662 add $statgrp aio_stat "$path/$entry/.", sub { 1190 add $statgrp aio_stat $wd, sub {
663 if ($_[0] < 0) { 1191 if ($_[0] < 0) {
664 push @nondirs, $entry; 1192 push @nondirs, $entry;
665 } else { 1193 } else {
666 # need to check for real directory 1194 # need to check for real directory
667 aioreq_pri $pri; 1195 aioreq_pri $pri;
1196 $wd->[1] = $entry;
668 add $statgrp aio_lstat "$path/$entry", sub { 1197 add $statgrp aio_lstat $wd, sub {
669 if (-d _) { 1198 if (-d _) {
670 push @dirs, $entry; 1199 push @dirs, $entry;
671 1200
672 unless (--$ndirs) { 1201 unless (--$ndirs) {
673 push @nondirs, @$entries; 1202 push @nondirs, @$entries;
674 feed $statgrp; 1203 feed $statgrp;
1204 }
1205 } else {
1206 push @nondirs, $entry;
675 } 1207 }
676 } else {
677 push @nondirs, $entry;
678 } 1208 }
679 } 1209 }
680 } 1210 };
681 }; 1211 };
682 }; 1212 };
683 }; 1213 };
684 }; 1214 };
685 }; 1215 };
686 1216
687 $grp 1217 $grp
688} 1218}
689 1219
1220=item aio_rmtree $pathname, $callback->($status)
1221
1222Delete a directory tree starting (and including) C<$path>, return the
1223status of the final C<rmdir> only. This is a composite request that
1224uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1225everything else.
1226
1227=cut
1228
1229sub aio_rmtree;
1230sub aio_rmtree($;$) {
1231 my ($path, $cb) = @_;
1232
1233 my $pri = aioreq_pri;
1234 my $grp = aio_group $cb;
1235
1236 aioreq_pri $pri;
1237 add $grp aio_scandir $path, 0, sub {
1238 my ($dirs, $nondirs) = @_;
1239
1240 my $dirgrp = aio_group sub {
1241 add $grp aio_rmdir $path, sub {
1242 $grp->result ($_[0]);
1243 };
1244 };
1245
1246 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
1247 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
1248
1249 add $grp $dirgrp;
1250 };
1251
1252 $grp
1253}
1254
1255=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
1256
1257=item aio_ioctl $fh, $request, $buf, $callback->($status)
1258
1259These work just like the C<fcntl> and C<ioctl> built-in functions, except
1260they execute asynchronously and pass the return value to the callback.
1261
1262Both calls can be used for a lot of things, some of which make more sense
1263to run asynchronously in their own thread, while some others make less
1264sense. For example, calls that block waiting for external events, such
1265as locking, will also lock down an I/O thread while it is waiting, which
1266can deadlock the whole I/O system. At the same time, there might be no
1267alternative to using a thread to wait.
1268
1269So in general, you should only use these calls for things that do
1270(filesystem) I/O, not for things that wait for other events (network,
1271other processes), although if you are careful and know what you are doing,
1272you still can.
1273
1274The following constants are available (missing ones are, as usual C<0>):
1275
1276C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
1277
1278C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
1279C<FS_IOC_FIEMAP>.
1280
1281C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
1282C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
1283
1284C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
1285C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
1286C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
1287C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
1288C<FS_FL_USER_MODIFIABLE>.
1289
1290C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
1291C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
1292C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
1293C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1294
1295=item aio_sync $callback->($status)
1296
1297Asynchronously call sync and call the callback when finished.
1298
690=item aio_fsync $fh, $callback->($status) 1299=item aio_fsync $fh, $callback->($status)
691 1300
692Asynchronously call fsync on the given filehandle and call the callback 1301Asynchronously call fsync on the given filehandle and call the callback
693with the fsync result code. 1302with the fsync result code.
694 1303
697Asynchronously call fdatasync on the given filehandle and call the 1306Asynchronously call fdatasync on the given filehandle and call the
698callback with the fdatasync result code. 1307callback with the fdatasync result code.
699 1308
700If this call isn't available because your OS lacks it or it couldn't be 1309If this call isn't available because your OS lacks it or it couldn't be
701detected, it will be emulated by calling C<fsync> instead. 1310detected, it will be emulated by calling C<fsync> instead.
1311
1312=item aio_syncfs $fh, $callback->($status)
1313
1314Asynchronously call the syncfs syscall to sync the filesystem associated
1315to the given filehandle and call the callback with the syncfs result
1316code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1317errno to C<ENOSYS> nevertheless.
1318
1319=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1320
1321Sync the data portion of the file specified by C<$offset> and C<$length>
1322to disk (but NOT the metadata), by calling the Linux-specific
1323sync_file_range call. If sync_file_range is not available or it returns
1324ENOSYS, then fdatasync or fsync is being substituted.
1325
1326C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1327C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1328C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1329manpage for details.
1330
1331=item aio_pathsync $pathname, $callback->($status)
1332
1333This request tries to open, fsync and close the given path. This is a
1334composite request intended to sync directories after directory operations
1335(E.g. rename). This might not work on all operating systems or have any
1336specific effect, but usually it makes sure that directory changes get
1337written to disc. It works for anything that can be opened for read-only,
1338not just directories.
1339
1340Future versions of this function might fall back to other methods when
1341C<fsync> on the directory fails (such as calling C<sync>).
1342
1343Passes C<0> when everything went ok, and C<-1> on error.
1344
1345=cut
1346
1347sub aio_pathsync($;$) {
1348 my ($path, $cb) = @_;
1349
1350 my $pri = aioreq_pri;
1351 my $grp = aio_group $cb;
1352
1353 aioreq_pri $pri;
1354 add $grp aio_open $path, O_RDONLY, 0, sub {
1355 my ($fh) = @_;
1356 if ($fh) {
1357 aioreq_pri $pri;
1358 add $grp aio_fsync $fh, sub {
1359 $grp->result ($_[0]);
1360
1361 aioreq_pri $pri;
1362 add $grp aio_close $fh;
1363 };
1364 } else {
1365 $grp->result (-1);
1366 }
1367 };
1368
1369 $grp
1370}
1371
1372=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1373
1374This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1375scalars (see the C<IO::AIO::mmap> function, although it also works on data
1376scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1377scalar must only be modified in-place while an aio operation is pending on
1378it).
1379
1380It calls the C<msync> function of your OS, if available, with the memory
1381area starting at C<$offset> in the string and ending C<$length> bytes
1382later. If C<$length> is negative, counts from the end, and if C<$length>
1383is C<undef>, then it goes till the end of the string. The flags can be
1384either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1385C<IO::AIO::MS_INVALIDATE>.
1386
1387=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1388
1389This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1390scalars.
1391
1392It touches (reads or writes) all memory pages in the specified
1393range inside the scalar. All caveats and parameters are the same
1394as for C<aio_msync>, above, except for flags, which must be either
1395C<0> (which reads all pages and ensures they are instantiated) or
1396C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1397writing an octet from it, which dirties the page).
1398
1399=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1400
1401This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1402scalars.
1403
1404It reads in all the pages of the underlying storage into memory (if any)
1405and locks them, so they are not getting swapped/paged out or removed.
1406
1407If C<$length> is undefined, then the scalar will be locked till the end.
1408
1409On systems that do not implement C<mlock>, this function returns C<-1>
1410and sets errno to C<ENOSYS>.
1411
1412Note that the corresponding C<munlock> is synchronous and is
1413documented under L<MISCELLANEOUS FUNCTIONS>.
1414
1415Example: open a file, mmap and mlock it - both will be undone when
1416C<$data> gets destroyed.
1417
1418 open my $fh, "<", $path or die "$path: $!";
1419 my $data;
1420 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1421 aio_mlock $data; # mlock in background
1422
1423=item aio_mlockall $flags, $callback->($status)
1424
1425Calls the C<mlockall> function with the given C<$flags> (a combination of
1426C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1427
1428On systems that do not implement C<mlockall>, this function returns C<-1>
1429and sets errno to C<ENOSYS>.
1430
1431Note that the corresponding C<munlockall> is synchronous and is
1432documented under L<MISCELLANEOUS FUNCTIONS>.
1433
1434Example: asynchronously lock all current and future pages into memory.
1435
1436 aio_mlockall IO::AIO::MCL_FUTURE;
1437
1438=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1439
1440Queries the extents of the given file (by calling the Linux C<FIEMAP>
1441ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
1442the ioctl is not available on your OS, then this request will fail with
1443C<ENOSYS>.
1444
1445C<$start> is the starting offset to query extents for, C<$length> is the
1446size of the range to query - if it is C<undef>, then the whole file will
1447be queried.
1448
1449C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
1450C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1451exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1452the data portion.
1453
1454C<$count> is the maximum number of extent records to return. If it is
1455C<undef>, then IO::AIO queries all extents of the range. As a very special
1456case, if it is C<0>, then the callback receives the number of extents
1457instead of the extents themselves (which is unreliable, see below).
1458
1459If an error occurs, the callback receives no arguments. The special
1460C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1461
1462Otherwise, the callback receives an array reference with extent
1463structures. Each extent structure is an array reference itself, with the
1464following members:
1465
1466 [$logical, $physical, $length, $flags]
1467
1468Flags is any combination of the following flag values (typically either C<0>
1469or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
1470
1471C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
1472C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
1473C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1474C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1475C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1476C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1477
1478At the time of this writing (Linux 3.2), this requets is unreliable unless
1479C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1480it to return all extents of a range for files with large number of
1481extents. The code works around all these issues if C<$count> is undef.
702 1482
703=item aio_group $callback->(...) 1483=item aio_group $callback->(...)
704 1484
705This is a very special aio request: Instead of doing something, it is a 1485This is a very special aio request: Instead of doing something, it is a
706container for other aio requests, which is useful if you want to bundle 1486container for other aio requests, which is useful if you want to bundle
744immense (it blocks a thread for a long time) so do not use this function 1524immense (it blocks a thread for a long time) so do not use this function
745except to put your application under artificial I/O pressure. 1525except to put your application under artificial I/O pressure.
746 1526
747=back 1527=back
748 1528
1529
1530=head2 IO::AIO::WD - multiple working directories
1531
1532Your process only has one current working directory, which is used by all
1533threads. This makes it hard to use relative paths (some other component
1534could call C<chdir> at any time, and it is hard to control when the path
1535will be used by IO::AIO).
1536
1537One solution for this is to always use absolute paths. This usually works,
1538but can be quite slow (the kernel has to walk the whole path on every
1539access), and can also be a hassle to implement.
1540
1541Newer POSIX systems have a number of functions (openat, fdopendir,
1542futimensat and so on) that make it possible to specify working directories
1543per operation.
1544
1545For portability, and because the clowns who "designed", or shall I write,
1546perpetrated this new interface were obviously half-drunk, this abstraction
1547cannot be perfect, though.
1548
1549IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1550object. This object stores the canonicalised, absolute version of the
1551path, and on systems that allow it, also a directory file descriptor.
1552
1553Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1554or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1555object and a pathname instead (or the IO::AIO::WD object alone, which
1556gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1557IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1558to that IO::AIO::WD object.
1559
1560For example, to get a wd object for F</etc> and then stat F<passwd>
1561inside, you would write:
1562
1563 aio_wd "/etc", sub {
1564 my $etcdir = shift;
1565
1566 # although $etcdir can be undef on error, there is generally no reason
1567 # to check for errors here, as aio_stat will fail with ENOENT
1568 # when $etcdir is undef.
1569
1570 aio_stat [$etcdir, "passwd"], sub {
1571 # yay
1572 };
1573 };
1574
1575The fact that C<aio_wd> is a request and not a normal function shows that
1576creating an IO::AIO::WD object is itself a potentially blocking operation,
1577which is why it is done asynchronously.
1578
1579To stat the directory obtained with C<aio_wd> above, one could write
1580either of the following three request calls:
1581
1582 aio_lstat "/etc" , sub { ... # pathname as normal string
1583 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1584 aio_lstat $wd , sub { ... # shorthand for the previous
1585
1586As with normal pathnames, IO::AIO keeps a copy of the working directory
1587object and the pathname string, so you could write the following without
1588causing any issues due to C<$path> getting reused:
1589
1590 my $path = [$wd, undef];
1591
1592 for my $name (qw(abc def ghi)) {
1593 $path->[1] = $name;
1594 aio_stat $path, sub {
1595 # ...
1596 };
1597 }
1598
1599There are some caveats: when directories get renamed (or deleted), the
1600pathname string doesn't change, so will point to the new directory (or
1601nowhere at all), while the directory fd, if available on the system,
1602will still point to the original directory. Most functions accepting a
1603pathname will use the directory fd on newer systems, and the string on
1604older systems. Some functions (such as realpath) will always rely on the
1605string form of the pathname.
1606
1607So this functionality is mainly useful to get some protection against
1608C<chdir>, to easily get an absolute path out of a relative path for future
1609reference, and to speed up doing many operations in the same directory
1610(e.g. when stat'ing all files in a directory).
1611
1612The following functions implement this working directory abstraction:
1613
1614=over 4
1615
1616=item aio_wd $pathname, $callback->($wd)
1617
1618Asynchonously canonicalise the given pathname and convert it to an
1619IO::AIO::WD object representing it. If possible and supported on the
1620system, also open a directory fd to speed up pathname resolution relative
1621to this working directory.
1622
1623If something goes wrong, then C<undef> is passwd to the callback instead
1624of a working directory object and C<$!> is set appropriately. Since
1625passing C<undef> as working directory component of a pathname fails the
1626request with C<ENOENT>, there is often no need for error checking in the
1627C<aio_wd> callback, as future requests using the value will fail in the
1628expected way.
1629
1630=item IO::AIO::CWD
1631
1632This is a compiletime constant (object) that represents the process
1633current working directory.
1634
1635Specifying this object as working directory object for a pathname is as if
1636the pathname would be specified directly, without a directory object. For
1637example, these calls are functionally identical:
1638
1639 aio_stat "somefile", sub { ... };
1640 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1641
1642=back
1643
1644To recover the path associated with an IO::AIO::WD object, you can use
1645C<aio_realpath>:
1646
1647 aio_realpath $wd, sub {
1648 warn "path is $_[0]\n";
1649 };
1650
1651Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
1652sometimes, fall back to using an absolue path.
1653
749=head2 IO::AIO::REQ CLASS 1654=head2 IO::AIO::REQ CLASS
750 1655
751All non-aggregate C<aio_*> functions return an object of this class when 1656All non-aggregate C<aio_*> functions return an object of this class when
752called in non-void context. 1657called in non-void context.
753 1658
756=item cancel $req 1661=item cancel $req
757 1662
758Cancels the request, if possible. Has the effect of skipping execution 1663Cancels the request, if possible. Has the effect of skipping execution
759when entering the B<execute> state and skipping calling the callback when 1664when entering the B<execute> state and skipping calling the callback when
760entering the the B<result> state, but will leave the request otherwise 1665entering the the B<result> state, but will leave the request otherwise
761untouched. That means that requests that currently execute will not be 1666untouched (with the exception of readdir). That means that requests that
762stopped and resources held by the request will not be freed prematurely. 1667currently execute will not be stopped and resources held by the request
1668will not be freed prematurely.
763 1669
764=item cb $req $callback->(...) 1670=item cb $req $callback->(...)
765 1671
766Replace (or simply set) the callback registered to the request. 1672Replace (or simply set) the callback registered to the request.
767 1673
818Their lifetime, simplified, looks like this: when they are empty, they 1724Their lifetime, simplified, looks like this: when they are empty, they
819will finish very quickly. If they contain only requests that are in the 1725will finish very quickly. If they contain only requests that are in the
820C<done> state, they will also finish. Otherwise they will continue to 1726C<done> state, they will also finish. Otherwise they will continue to
821exist. 1727exist.
822 1728
823That means after creating a group you have some time to add requests. And 1729That means after creating a group you have some time to add requests
824in the callbacks of those requests, you can add further requests to the 1730(precisely before the callback has been invoked, which is only done within
825group. And only when all those requests have finished will the the group 1731the C<poll_cb>). And in the callbacks of those requests, you can add
826itself finish. 1732further requests to the group. And only when all those requests have
1733finished will the the group itself finish.
827 1734
828=over 4 1735=over 4
829 1736
830=item add $grp ... 1737=item add $grp ...
831 1738
840=item $grp->cancel_subs 1747=item $grp->cancel_subs
841 1748
842Cancel all subrequests and clears any feeder, but not the group request 1749Cancel all subrequests and clears any feeder, but not the group request
843itself. Useful when you queued a lot of events but got a result early. 1750itself. Useful when you queued a lot of events but got a result early.
844 1751
1752The group request will finish normally (you cannot add requests to the
1753group).
1754
845=item $grp->result (...) 1755=item $grp->result (...)
846 1756
847Set the result value(s) that will be passed to the group callback when all 1757Set the result value(s) that will be passed to the group callback when all
848subrequests have finished and set thre groups errno to the current value 1758subrequests have finished and set the groups errno to the current value
849of errno (just like calling C<errno> without an error number). By default, 1759of errno (just like calling C<errno> without an error number). By default,
850no argument will be passed and errno is zero. 1760no argument will be passed and errno is zero.
851 1761
852=item $grp->errno ([$errno]) 1762=item $grp->errno ([$errno])
853 1763
864=item feed $grp $callback->($grp) 1774=item feed $grp $callback->($grp)
865 1775
866Sets a feeder/generator on this group: every group can have an attached 1776Sets a feeder/generator on this group: every group can have an attached
867generator that generates requests if idle. The idea behind this is that, 1777generator that generates requests if idle. The idea behind this is that,
868although you could just queue as many requests as you want in a group, 1778although you could just queue as many requests as you want in a group,
869this might starve other requests for a potentially long time. For 1779this might starve other requests for a potentially long time. For example,
870example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> 1780C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
871requests, delaying any later requests for a long time. 1781requests, delaying any later requests for a long time.
872 1782
873To avoid this, and allow incremental generation of requests, you can 1783To avoid this, and allow incremental generation of requests, you can
874instead a group and set a feeder on it that generates those requests. The 1784instead a group and set a feeder on it that generates those requests. The
875feed callback will be called whenever there are few enough (see C<limit>, 1785feed callback will be called whenever there are few enough (see C<limit>,
880not impose any limits). 1790not impose any limits).
881 1791
882If the feed does not queue more requests when called, it will be 1792If the feed does not queue more requests when called, it will be
883automatically removed from the group. 1793automatically removed from the group.
884 1794
885If the feed limit is C<0>, it will be set to C<2> automatically. 1795If the feed limit is C<0> when this method is called, it will be set to
1796C<2> automatically.
886 1797
887Example: 1798Example:
888 1799
889 # stat all files in @files, but only ever use four aio requests concurrently: 1800 # stat all files in @files, but only ever use four aio requests concurrently:
890 1801
902Sets the feeder limit for the group: The feeder will be called whenever 1813Sets the feeder limit for the group: The feeder will be called whenever
903the group contains less than this many requests. 1814the group contains less than this many requests.
904 1815
905Setting the limit to C<0> will pause the feeding process. 1816Setting the limit to C<0> will pause the feeding process.
906 1817
1818The default value for the limit is C<0>, but note that setting a feeder
1819automatically bumps it up to C<2>.
1820
907=back 1821=back
908 1822
909=head2 SUPPORT FUNCTIONS 1823=head2 SUPPORT FUNCTIONS
910 1824
911=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 1825=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
913=over 4 1827=over 4
914 1828
915=item $fileno = IO::AIO::poll_fileno 1829=item $fileno = IO::AIO::poll_fileno
916 1830
917Return the I<request result pipe file descriptor>. This filehandle must be 1831Return the I<request result pipe file descriptor>. This filehandle must be
918polled for reading by some mechanism outside this module (e.g. Event or 1832polled for reading by some mechanism outside this module (e.g. EV, Glib,
919select, see below or the SYNOPSIS). If the pipe becomes readable you have 1833select and so on, see below or the SYNOPSIS). If the pipe becomes readable
920to call C<poll_cb> to check the results. 1834you have to call C<poll_cb> to check the results.
921 1835
922See C<poll_cb> for an example. 1836See C<poll_cb> for an example.
923 1837
924=item IO::AIO::poll_cb 1838=item IO::AIO::poll_cb
925 1839
926Process some outstanding events on the result pipe. You have to call this 1840Process some requests that have reached the result phase (i.e. they have
927regularly. Returns the number of events processed. Returns immediately 1841been executed but the results are not yet reported). You have to call
928when no events are outstanding. The amount of events processed depends on 1842this "regularly" to finish outstanding requests.
929the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
930 1843
1844Returns C<0> if all events could be processed (or there were no
1845events to process), or C<-1> if it returned earlier for whatever
1846reason. Returns immediately when no events are outstanding. The amount
1847of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1848C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1849
931If not all requests were processed for whatever reason, the filehandle 1850If not all requests were processed for whatever reason, the poll file
932will still be ready when C<poll_cb> returns. 1851descriptor will still be ready when C<poll_cb> returns, so normally you
1852don't have to do anything special to have it called later.
1853
1854Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1855ready, it can be beneficial to call this function from loops which submit
1856a lot of requests, to make sure the results get processed when they become
1857available and not just when the loop is finished and the event loop takes
1858over again. This function returns very fast when there are no outstanding
1859requests.
933 1860
934Example: Install an Event watcher that automatically calls 1861Example: Install an Event watcher that automatically calls
935IO::AIO::poll_cb with high priority: 1862IO::AIO::poll_cb with high priority (more examples can be found in the
1863SYNOPSIS section, at the top of this document):
936 1864
937 Event->io (fd => IO::AIO::poll_fileno, 1865 Event->io (fd => IO::AIO::poll_fileno,
938 poll => 'r', async => 1, 1866 poll => 'r', async => 1,
939 cb => \&IO::AIO::poll_cb); 1867 cb => \&IO::AIO::poll_cb);
1868
1869=item IO::AIO::poll_wait
1870
1871Wait until either at least one request is in the result phase or no
1872requests are outstanding anymore.
1873
1874This is useful if you want to synchronously wait for some requests to
1875become ready, without actually handling them.
1876
1877See C<nreqs> for an example.
1878
1879=item IO::AIO::poll
1880
1881Waits until some requests have been handled.
1882
1883Returns the number of requests processed, but is otherwise strictly
1884equivalent to:
1885
1886 IO::AIO::poll_wait, IO::AIO::poll_cb
1887
1888=item IO::AIO::flush
1889
1890Wait till all outstanding AIO requests have been handled.
1891
1892Strictly equivalent to:
1893
1894 IO::AIO::poll_wait, IO::AIO::poll_cb
1895 while IO::AIO::nreqs;
940 1896
941=item IO::AIO::max_poll_reqs $nreqs 1897=item IO::AIO::max_poll_reqs $nreqs
942 1898
943=item IO::AIO::max_poll_time $seconds 1899=item IO::AIO::max_poll_time $seconds
944 1900
969 # use a low priority so other tasks have priority 1925 # use a low priority so other tasks have priority
970 Event->io (fd => IO::AIO::poll_fileno, 1926 Event->io (fd => IO::AIO::poll_fileno,
971 poll => 'r', nice => 1, 1927 poll => 'r', nice => 1,
972 cb => &IO::AIO::poll_cb); 1928 cb => &IO::AIO::poll_cb);
973 1929
974=item IO::AIO::poll_wait 1930=back
975
976If there are any outstanding requests and none of them in the result
977phase, wait till the result filehandle becomes ready for reading (simply
978does a C<select> on the filehandle. This is useful if you want to
979synchronously wait for some requests to finish).
980
981See C<nreqs> for an example.
982
983=item IO::AIO::poll
984
985Waits until some requests have been handled.
986
987Returns the number of requests processed, but is otherwise strictly
988equivalent to:
989
990 IO::AIO::poll_wait, IO::AIO::poll_cb
991
992=item IO::AIO::flush
993
994Wait till all outstanding AIO requests have been handled.
995
996Strictly equivalent to:
997
998 IO::AIO::poll_wait, IO::AIO::poll_cb
999 while IO::AIO::nreqs;
1000 1931
1001=head3 CONTROLLING THE NUMBER OF THREADS 1932=head3 CONTROLLING THE NUMBER OF THREADS
1933
1934=over
1002 1935
1003=item IO::AIO::min_parallel $nthreads 1936=item IO::AIO::min_parallel $nthreads
1004 1937
1005Set the minimum number of AIO threads to C<$nthreads>. The current 1938Set the minimum number of AIO threads to C<$nthreads>. The current
1006default is C<8>, which means eight asynchronous operations can execute 1939default is C<8>, which means eight asynchronous operations can execute
1034 1967
1035Under normal circumstances you don't need to call this function. 1968Under normal circumstances you don't need to call this function.
1036 1969
1037=item IO::AIO::max_idle $nthreads 1970=item IO::AIO::max_idle $nthreads
1038 1971
1039Limit the number of threads (default: 4) that are allowed to idle (i.e., 1972Limit the number of threads (default: 4) that are allowed to idle
1040threads that did not get a request to process within 10 seconds). That 1973(i.e., threads that did not get a request to process within the idle
1041means if a thread becomes idle while C<$nthreads> other threads are also 1974timeout (default: 10 seconds). That means if a thread becomes idle while
1042idle, it will free its resources and exit. 1975C<$nthreads> other threads are also idle, it will free its resources and
1976exit.
1043 1977
1044This is useful when you allow a large number of threads (e.g. 100 or 1000) 1978This is useful when you allow a large number of threads (e.g. 100 or 1000)
1045to allow for extremely high load situations, but want to free resources 1979to allow for extremely high load situations, but want to free resources
1046under normal circumstances (1000 threads can easily consume 30MB of RAM). 1980under normal circumstances (1000 threads can easily consume 30MB of RAM).
1047 1981
1048The default is probably ok in most situations, especially if thread 1982The default is probably ok in most situations, especially if thread
1049creation is fast. If thread creation is very slow on your system you might 1983creation is fast. If thread creation is very slow on your system you might
1050want to use larger values. 1984want to use larger values.
1051 1985
1986=item IO::AIO::idle_timeout $seconds
1987
1988Sets the minimum idle timeout (default 10) after which worker threads are
1989allowed to exit. SEe C<IO::AIO::max_idle>.
1990
1052=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1991=item IO::AIO::max_outstanding $maxreqs
1992
1993Sets the maximum number of outstanding requests to C<$nreqs>. If
1994you do queue up more than this number of requests, the next call to
1995C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1996C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1997longer exceeded.
1998
1999In other words, this setting does not enforce a queue limit, but can be
2000used to make poll functions block if the limit is exceeded.
1053 2001
1054This is a very bad function to use in interactive programs because it 2002This is a very bad function to use in interactive programs because it
1055blocks, and a bad way to reduce concurrency because it is inexact: Better 2003blocks, and a bad way to reduce concurrency because it is inexact: Better
1056use an C<aio_group> together with a feed callback. 2004use an C<aio_group> together with a feed callback.
1057 2005
1058Sets the maximum number of outstanding requests to C<$nreqs>. If you 2006Its main use is in scripts without an event loop - when you want to stat
1059to queue up more than this number of requests, the next call to the 2007a lot of files, you can write somehting like this:
1060C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1061function will block until the limit is no longer exceeded.
1062 2008
1063The default value is very large, so there is no practical limit on the 2009 IO::AIO::max_outstanding 32;
1064number of outstanding requests.
1065 2010
1066You can still queue as many requests as you want. Therefore, 2011 for my $path (...) {
1067C<max_oustsanding> is mainly useful in simple scripts (with low values) or 2012 aio_stat $path , ...;
1068as a stop gap to shield against fatal memory overflow (with large values). 2013 IO::AIO::poll_cb;
2014 }
2015
2016 IO::AIO::flush;
2017
2018The call to C<poll_cb> inside the loop will normally return instantly, but
2019as soon as more thna C<32> reqeusts are in-flight, it will block until
2020some requests have been handled. This keeps the loop from pushing a large
2021number of C<aio_stat> requests onto the queue.
2022
2023The default value for C<max_outstanding> is very large, so there is no
2024practical limit on the number of outstanding requests.
2025
2026=back
1069 2027
1070=head3 STATISTICAL INFORMATION 2028=head3 STATISTICAL INFORMATION
2029
2030=over
1071 2031
1072=item IO::AIO::nreqs 2032=item IO::AIO::nreqs
1073 2033
1074Returns the number of requests currently in the ready, execute or pending 2034Returns the number of requests currently in the ready, execute or pending
1075states (i.e. for which their callback has not been invoked yet). 2035states (i.e. for which their callback has not been invoked yet).
1089Returns the number of requests currently in the pending state (executed, 2049Returns the number of requests currently in the pending state (executed,
1090but not yet processed by poll_cb). 2050but not yet processed by poll_cb).
1091 2051
1092=back 2052=back
1093 2053
2054=head3 MISCELLANEOUS FUNCTIONS
2055
2056IO::AIO implements some functions that are useful when you want to use
2057some "Advanced I/O" function not available to in Perl, without going the
2058"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
2059counterpart.
2060
2061=over 4
2062
2063=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
2064
2065Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
2066but is blocking (this makes most sense if you know the input data is
2067likely cached already and the output filehandle is set to non-blocking
2068operations).
2069
2070Returns the number of bytes copied, or C<-1> on error.
2071
2072=item IO::AIO::fadvise $fh, $offset, $len, $advice
2073
2074Simply calls the C<posix_fadvise> function (see its
2075manpage for details). The following advice constants are
2076available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
2077C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
2078C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
2079
2080On systems that do not implement C<posix_fadvise>, this function returns
2081ENOSYS, otherwise the return value of C<posix_fadvise>.
2082
2083=item IO::AIO::madvise $scalar, $offset, $len, $advice
2084
2085Simply calls the C<posix_madvise> function (see its
2086manpage for details). The following advice constants are
2087available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
2088C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
2089C<IO::AIO::MADV_FREE>.
2090
2091If C<$offset> is negative, counts from the end. If C<$length> is negative,
2092the remaining length of the C<$scalar> is used. If possible, C<$length>
2093will be reduced to fit into the C<$scalar>.
2094
2095On systems that do not implement C<posix_madvise>, this function returns
2096ENOSYS, otherwise the return value of C<posix_madvise>.
2097
2098=item IO::AIO::mprotect $scalar, $offset, $len, $protect
2099
2100Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
2101$scalar (see its manpage for details). The following protect
2102constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
2103C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
2104
2105If C<$offset> is negative, counts from the end. If C<$length> is negative,
2106the remaining length of the C<$scalar> is used. If possible, C<$length>
2107will be reduced to fit into the C<$scalar>.
2108
2109On systems that do not implement C<mprotect>, this function returns
2110ENOSYS, otherwise the return value of C<mprotect>.
2111
2112=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
2113
2114Memory-maps a file (or anonymous memory range) and attaches it to the
2115given C<$scalar>, which will act like a string scalar. Returns true on
2116success, and false otherwise.
2117
2118The scalar must exist, but its contents do not matter - this means you
2119cannot use a nonexistant array or hash element. When in doubt, C<undef>
2120the scalar first.
2121
2122The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
2123which don't change the string length, and most read-only operations such
2124as copying it or searching it with regexes and so on.
2125
2126Anything else is unsafe and will, at best, result in memory leaks.
2127
2128The memory map associated with the C<$scalar> is automatically removed
2129when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
2130or C<IO::AIO::munmap> functions are called on it.
2131
2132This calls the C<mmap>(2) function internally. See your system's manual
2133page for details on the C<$length>, C<$prot> and C<$flags> parameters.
2134
2135The C<$length> must be larger than zero and smaller than the actual
2136filesize.
2137
2138C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
2139C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
2140
2141C<$flags> can be a combination of
2142C<IO::AIO::MAP_SHARED> or
2143C<IO::AIO::MAP_PRIVATE>,
2144or a number of system-specific flags (when not available, the are C<0>):
2145C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
2146C<IO::AIO::MAP_LOCKED>,
2147C<IO::AIO::MAP_NORESERVE>,
2148C<IO::AIO::MAP_POPULATE>,
2149C<IO::AIO::MAP_NONBLOCK>,
2150C<IO::AIO::MAP_FIXED>,
2151C<IO::AIO::MAP_GROWSDOWN>,
2152C<IO::AIO::MAP_32BIT>,
2153C<IO::AIO::MAP_HUGETLB> or
2154C<IO::AIO::MAP_STACK>.
2155
2156If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
2157
2158C<$offset> is the offset from the start of the file - it generally must be
2159a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
2160
2161Example:
2162
2163 use Digest::MD5;
2164 use IO::AIO;
2165
2166 open my $fh, "<verybigfile"
2167 or die "$!";
2168
2169 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
2170 or die "verybigfile: $!";
2171
2172 my $fast_md5 = md5 $data;
2173
2174=item IO::AIO::munmap $scalar
2175
2176Removes a previous mmap and undefines the C<$scalar>.
2177
2178=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
2179
2180Calls the C<munlock> function, undoing the effects of a previous
2181C<aio_mlock> call (see its description for details).
2182
2183=item IO::AIO::munlockall
2184
2185Calls the C<munlockall> function.
2186
2187On systems that do not implement C<munlockall>, this function returns
2188ENOSYS, otherwise the return value of C<munlockall>.
2189
2190=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
2191
2192Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
2193C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
2194should be the file offset.
2195
2196C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
2197silently corrupt the data in this case.
2198
2199The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
2200C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
2201C<IO::AIO::SPLICE_F_GIFT>.
2202
2203See the C<splice(2)> manpage for details.
2204
2205=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
2206
2207Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
2208description for C<IO::AIO::splice> above for details.
2209
2210=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
2211
2212Attempts to query or change the pipe buffer size. Obviously works only
2213on pipes, and currently works only on GNU/Linux systems, and fails with
2214C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
2215size on other systems, drop me a note.
2216
2217=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
2218
2219This is a direct interface to the Linux L<pipe2(2)> system call. If
2220C<$flags> is missing or C<0>, then this should be the same as a call to
2221perl's built-in C<pipe> function and create a new pipe, and works on
2222systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
2223(..., 4096, O_BINARY)>.
2224
2225If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
2226the given flags (Linux 2.6.27, glibc 2.9).
2227
2228On success, the read and write file handles are returned.
2229
2230On error, nothing will be returned. If the pipe2 syscall is missing and
2231C<$flags> is non-zero, fails with C<ENOSYS>.
2232
2233Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
2234time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
2235C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
2236
2237=back
2238
1094=cut 2239=cut
1095 2240
1096# support function to convert a fd into a perl filehandle
1097sub _fd2fh {
1098 return undef if $_[0] < 0;
1099
1100 # try to generate nice filehandles
1101 my $sym = "IO::AIO::fd#$_[0]";
1102 local *$sym;
1103
1104 open *$sym, "+<&=$_[0]" # usually works under any unix
1105 or open *$sym, "<&=$_[0]" # cygwin needs this
1106 or open *$sym, ">&=$_[0]" # or this
1107 or return undef;
1108
1109 *$sym
1110}
1111
1112min_parallel 8; 2241min_parallel 8;
1113 2242
1114END { 2243END { flush }
1115 min_parallel 1;
1116 flush;
1117};
1118 2244
11191; 22451;
1120 2246
2247=head1 EVENT LOOP INTEGRATION
2248
2249It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
2250automatically into many event loops:
2251
2252 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
2253 use AnyEvent::AIO;
2254
2255You can also integrate IO::AIO manually into many event loops, here are
2256some examples of how to do this:
2257
2258 # EV integration
2259 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
2260
2261 # Event integration
2262 Event->io (fd => IO::AIO::poll_fileno,
2263 poll => 'r',
2264 cb => \&IO::AIO::poll_cb);
2265
2266 # Glib/Gtk2 integration
2267 add_watch Glib::IO IO::AIO::poll_fileno,
2268 in => sub { IO::AIO::poll_cb; 1 };
2269
2270 # Tk integration
2271 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
2272 readable => \&IO::AIO::poll_cb);
2273
2274 # Danga::Socket integration
2275 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
2276 \&IO::AIO::poll_cb);
2277
1121=head2 FORK BEHAVIOUR 2278=head2 FORK BEHAVIOUR
1122 2279
1123This module should do "the right thing" when the process using it forks: 2280Usage of pthreads in a program changes the semantics of fork
2281considerably. Specifically, only async-safe functions can be called after
2282fork. Perl doesn't know about this, so in general, you cannot call fork
2283with defined behaviour in perl if pthreads are involved. IO::AIO uses
2284pthreads, so this applies, but many other extensions and (for inexplicable
2285reasons) perl itself often is linked against pthreads, so this limitation
2286applies to quite a lot of perls.
1124 2287
1125Before the fork, IO::AIO enters a quiescent state where no requests 2288This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1126can be added in other threads and no results will be processed. After 2289only works in the process that loaded it. Forking is fully supported, but
1127the fork the parent simply leaves the quiescent state and continues 2290using IO::AIO in the child is not.
1128request/result processing, while the child frees the request/result queue
1129(so that the requests started before the fork will only be handled in the
1130parent). Threads will be started on demand until the limit set in the
1131parent process has been reached again.
1132 2291
1133In short: the parent will, after a short pause, continue as if fork had 2292You might get around by not I<using> IO::AIO before (or after)
1134not been called, while the child will act as if IO::AIO has not been used 2293forking. You could also try to call the L<IO::AIO::reinit> function in the
1135yet. 2294child:
2295
2296=over 4
2297
2298=item IO::AIO::reinit
2299
2300Abandons all current requests and I/O threads and simply reinitialises all
2301data structures. This is not an operation supported by any standards, but
2302happens to work on GNU/Linux and some newer BSD systems.
2303
2304The only reasonable use for this function is to call it after forking, if
2305C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
2306the process will result in undefined behaviour. Calling it at any time
2307will also result in any undefined (by POSIX) behaviour.
2308
2309=back
1136 2310
1137=head2 MEMORY USAGE 2311=head2 MEMORY USAGE
1138 2312
1139Per-request usage: 2313Per-request usage:
1140 2314
1142bytes of memory. In addition, stat requests need a stat buffer (possibly 2316bytes of memory. In addition, stat requests need a stat buffer (possibly
1143a few hundred bytes), readdir requires a result buffer and so on. Perl 2317a few hundred bytes), readdir requires a result buffer and so on. Perl
1144scalars and other data passed into aio requests will also be locked and 2318scalars and other data passed into aio requests will also be locked and
1145will consume memory till the request has entered the done state. 2319will consume memory till the request has entered the done state.
1146 2320
1147This is now awfully much, so queuing lots of requests is not usually a 2321This is not awfully much, so queuing lots of requests is not usually a
1148problem. 2322problem.
1149 2323
1150Per-thread usage: 2324Per-thread usage:
1151 2325
1152In the execution phase, some aio requests require more memory for 2326In the execution phase, some aio requests require more memory for
1157 2331
1158Known bugs will be fixed in the next release. 2332Known bugs will be fixed in the next release.
1159 2333
1160=head1 SEE ALSO 2334=head1 SEE ALSO
1161 2335
1162L<Coro::AIO>. 2336L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
2337more natural syntax.
1163 2338
1164=head1 AUTHOR 2339=head1 AUTHOR
1165 2340
1166 Marc Lehmann <schmorp@schmorp.de> 2341 Marc Lehmann <schmorp@schmorp.de>
1167 http://home.schmorp.de/ 2342 http://home.schmorp.de/

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