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Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs.
Revision 1.117 by root, Sat Oct 6 14:05:19 2007 UTC

… …
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", 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
… …
50 51
51=head1 DESCRIPTION 52=head1 DESCRIPTION
52 53
53This module implements asynchronous I/O using whatever means your 54This module implements asynchronous I/O using whatever means your
54operating system supports. 55operating system supports.
56
57Asynchronous means that operations that can normally block your program
58(e.g. reading from disk) will be done asynchronously: the operation
59will still block, but you can do something else in the meantime. This
60is extremely useful for programs that need to stay interactive even
61when doing heavy I/O (GUI programs, high performance network servers
62etc.), but can also be used to easily do operations in parallel that are
63normally done sequentially, e.g. stat'ing many files, which is much faster
64on a RAID volume or over NFS when you do a number of stat operations
65concurrently.
66
67While most of this works on all types of file descriptors (for
68example sockets), using these functions on file descriptors that
69support nonblocking operation (again, sockets, pipes etc.) is very
70inefficient. Use an event loop for that (such as the L<Event|Event>
71module): IO::AIO will naturally fit into such an event loop itself.
55 72
56In this version, a number of threads are started that execute your 73In this version, a number of threads are started that execute your
57requests and signal their completion. You don't need thread support 74requests and signal their completion. You don't need thread support
58in perl, and the threads created by this module will not be visible 75in perl, and the threads created by this module will not be visible
59to perl. In the future, this module might make use of the native aio 76to perl. In the future, this module might make use of the native aio
60functions available on many operating systems. However, they are often 77functions available on many operating systems. However, they are often
61not well-supported or restricted (Linux doesn't allow them on normal 78not well-supported or restricted (GNU/Linux doesn't allow them on normal
62files currently, for example), and they would only support aio_read and 79files currently, for example), and they would only support aio_read and
63aio_write, so the remaining functionality would have to be implemented 80aio_write, so the remaining functionality would have to be implemented
64using threads anyway. 81using threads anyway.
65 82
66Although the module will work with in the presence of other (Perl-) 83Although the module will work in the presence of other (Perl-) threads,
67threads, it is currently not reentrant in any way, so use appropriate 84it is currently not reentrant in any way, so use appropriate locking
68locking yourself, always call C<poll_cb> from within the same thread, or 85yourself, always call C<poll_cb> from within the same thread, or never
69never call C<poll_cb> (or other C<aio_> functions) recursively. 86call C<poll_cb> (or other C<aio_> functions) recursively.
87
88=head2 EXAMPLE
89
90This is a simple example that uses the Event module and loads
91F</etc/passwd> asynchronously:
92
93 use Fcntl;
94 use Event;
95 use IO::AIO;
96
97 # register the IO::AIO callback with Event
98 Event->io (fd => IO::AIO::poll_fileno,
99 poll => 'r',
100 cb => \&IO::AIO::poll_cb);
101
102 # queue the request to open /etc/passwd
103 aio_open "/etc/passwd", O_RDONLY, 0, sub {
104 my $fh = shift
105 or die "error while opening: $!";
106
107 # stat'ing filehandles is generally non-blocking
108 my $size = -s $fh;
109
110 # queue a request to read the file
111 my $contents;
112 aio_read $fh, 0, $size, $contents, 0, sub {
113 $_[0] == $size
114 or die "short read: $!";
115
116 close $fh;
117
118 # file contents now in $contents
119 print $contents;
120
121 # exit event loop and program
122 Event::unloop;
123 };
124 };
125
126 # possibly queue up other requests, or open GUI windows,
127 # check for sockets etc. etc.
128
129 # process events as long as there are some:
130 Event::loop;
70 131
71=head1 REQUEST ANATOMY AND LIFETIME 132=head1 REQUEST ANATOMY AND LIFETIME
72 133
73Every C<aio_*> function creates a request. which is a C data structure not 134Every C<aio_*> function creates a request. which is a C data structure not
74directly visible to Perl. 135directly visible to Perl.
… …
116Request has reached the end of its lifetime and holds no resources anymore 177Request has reached the end of its lifetime and holds no resources anymore
117(except possibly for the Perl object, but its connection to the actual 178(except possibly for the Perl object, but its connection to the actual
118aio request is severed and calling its methods will either do nothing or 179aio request is severed and calling its methods will either do nothing or
119result in a runtime error). 180result in a runtime error).
120 181
182=back
183
121=cut 184=cut
122 185
123package IO::AIO; 186package IO::AIO;
187
188use Carp ();
124 189
125no warnings; 190no warnings;
126use strict 'vars'; 191use strict 'vars';
127 192
128use base 'Exporter'; 193use base 'Exporter';
129 194
130BEGIN { 195BEGIN {
131 our $VERSION = '2.0'; 196 our $VERSION = '2.51';
132 197
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 198 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
134 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 199 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
135 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move 200 aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
136 aio_group aio_nop); 201 aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
202 aio_chown aio_chmod aio_utime aio_truncate);
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 203 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 204 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel nreqs nready npending); 205 min_parallel max_parallel max_idle
206 nreqs nready npending nthreads
207 max_poll_time max_poll_reqs);
140 208
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 209 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 210
143 require XSLoader; 211 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 212 XSLoader::load ("IO::AIO", $VERSION);
145} 213}
146 214
147=head1 FUNCTIONS 215=head1 FUNCTIONS
148 216
149=head2 AIO FUNCTIONS 217=head2 AIO REQUEST FUNCTIONS
150 218
151All the C<aio_*> calls are more or less thin wrappers around the syscall 219All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 220with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 221and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 222which must be a code reference. This code reference will get called with
… …
157syscall has been executed asynchronously. 225syscall has been executed asynchronously.
158 226
159All functions expecting a filehandle keep a copy of the filehandle 227All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 228internally until the request has finished.
161 229
162All requests return objects of type L<IO::AIO::REQ> that allow further 230All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 231further manipulation of those requests while they are in-flight.
164 232
165The pathnames you pass to these routines I<must> be absolute and 233The pathnames you pass to these routines I<must> be absolute and
166encoded in byte form. The reason for the former is that at the time the 234encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 235request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 236changed. Alternatively, you can make sure that you never change the
169current working directory. 237current working directory anywhere in the program and then use relative
238paths.
170 239
171To encode pathnames to byte form, either make sure you either: a) 240To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 241in filenames you got from outside (command line, readdir etc.) without
173etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode 242tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174your pathnames to the locale (or other) encoding in effect in the user 243your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 244environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 245use something else to ensure your scalar has the correct contents.
246
247This works, btw. independent of the internal UTF-8 bit, which IO::AIO
248handles correctly wether it is set or not.
177 249
178=over 4 250=over 4
179 251
180=item $prev_pri = aioreq_pri [$pri] 252=item $prev_pri = aioreq_pri [$pri]
181 253
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201 aio_read $_[0], ..., sub { 273 aio_read $_[0], ..., sub {
202 ... 274 ...
203 }; 275 };
204 }; 276 };
205 277
278
206=item aioreq_nice $pri_adjust 279=item aioreq_nice $pri_adjust
207 280
208Similar to C<aioreq_pri>, but subtracts the given value from the current 281Similar to C<aioreq_pri>, but subtracts the given value from the current
209priority, so effects are cumulative. 282priority, so the effect is cumulative.
283
210 284
211=item aio_open $pathname, $flags, $mode, $callback->($fh) 285=item aio_open $pathname, $flags, $mode, $callback->($fh)
212 286
213Asynchronously open or create a file and call the callback with a newly 287Asynchronously open or create a file and call the callback with a newly
214created filehandle for the file. 288created filehandle for the file.
… …
220list. They are the same as used by C<sysopen>. 294list. They are the same as used by C<sysopen>.
221 295
222Likewise, C<$mode> specifies the mode of the newly created file, if it 296Likewise, C<$mode> specifies the mode of the newly created file, if it
223didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, 297didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
224except that it is mandatory (i.e. use C<0> if you don't create new files, 298except that it is mandatory (i.e. use C<0> if you don't create new files,
225and C<0666> or C<0777> if you do). 299and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
300by the umask in effect then the request is being executed, so better never
301change the umask.
226 302
227Example: 303Example:
228 304
229 aio_open "/etc/passwd", O_RDONLY, 0, sub { 305 aio_open "/etc/passwd", O_RDONLY, 0, sub {
230 if ($_[0]) { 306 if ($_[0]) {
… …
233 } else { 309 } else {
234 die "open failed: $!\n"; 310 die "open failed: $!\n";
235 } 311 }
236 }; 312 };
237 313
314
238=item aio_close $fh, $callback->($status) 315=item aio_close $fh, $callback->($status)
239 316
240Asynchronously close a file and call the callback with the result 317Asynchronously close a file and call the callback with the result
241code. I<WARNING:> although accepted, you should not pass in a perl 318code.
242filehandle here, as perl will likely close the file descriptor another
243time when the filehandle is destroyed. Normally, you can safely call perls
244C<close> or just let filehandles go out of scope.
245 319
246This is supposed to be a bug in the API, so that might change. It's 320Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
247therefore best to avoid this function. 321closing the file descriptor associated with the filehandle itself. Here is
322what aio_close will try:
323
324 1. dup()licate the fd
325 2. asynchronously close() the duplicated fd
326 3. dup()licate the fd once more
327 4. let perl close() the filehandle
328 5. asynchronously close the duplicated fd
329
330The idea is that the first close() flushes stuff to disk that closing an
331fd will flush, so when perl closes the fd, nothing much will need to be
332flushed. The second async. close() will then flush stuff to disk that
333closing the last fd to the file will flush.
334
335Just FYI, SuSv3 has this to say on close:
336
337 All outstanding record locks owned by the process on the file
338 associated with the file descriptor shall be removed.
339
340 If fildes refers to a socket, close() shall cause the socket to be
341 destroyed. ... close() shall block for up to the current linger
342 interval until all data is transmitted.
343 [this actually sounds like a specification bug, but who knows]
344
345And at least Linux additionally actually flushes stuff on every close,
346even when the file itself is still open.
347
348Sounds enourmously inefficient and complicated? Yes... please show me how
349to nuke perl's fd out of existence...
350
351=cut
352
353sub aio_close($;$) {
354 aio_block {
355 my ($fh, $cb) = @_;
356
357 my $pri = aioreq_pri;
358 my $grp = aio_group $cb;
359
360 my $fd = fileno $fh;
361
362 defined $fd or Carp::croak "aio_close called with fd-less filehandle";
363
364 # if the dups fail we will simply get EBADF
365 my $fd2 = _dup $fd;
366 aioreq_pri $pri;
367 add $grp _aio_close $fd2, sub {
368 my $fd2 = _dup $fd;
369 close $fh;
370 aioreq_pri $pri;
371 add $grp _aio_close $fd2, sub {
372 $grp->result ($_[0]);
373 };
374 };
375
376 $grp
377 }
378}
379
248 380
249=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 381=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250 382
251=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 383=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252 384
253Reads or writes C<length> bytes from the specified C<fh> and C<offset> 385Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
254into the scalar given by C<data> and offset C<dataoffset> and calls the 386into the scalar given by C<$data> and offset C<$dataoffset> and calls the
255callback without the actual number of bytes read (or -1 on error, just 387callback without the actual number of bytes read (or -1 on error, just
256like the syscall). 388like the syscall).
257 389
390If C<$offset> is undefined, then the current file descriptor offset will
391be used (and updated), otherwise the file descriptor offset will not be
392changed by these calls.
393
394If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
395
396If C<$dataoffset> is less than zero, it will be counted from the end of
397C<$data>.
398
258The C<$data> scalar I<MUST NOT> be modified in any way while the request 399The C<$data> scalar I<MUST NOT> be modified in any way while the request
259is outstanding. Modifying it can result in segfaults or WW3 (if the 400is outstanding. Modifying it can result in segfaults or World War III (if
260necessary/optional hardware is installed). 401the necessary/optional hardware is installed).
261 402
262Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 403Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263offset C<0> within the scalar: 404offset C<0> within the scalar:
264 405
265 aio_read $fh, 7, 15, $buffer, 0, sub { 406 aio_read $fh, 7, 15, $buffer, 0, sub {
266 $_[0] > 0 or die "read error: $!"; 407 $_[0] > 0 or die "read error: $!";
267 print "read $_[0] bytes: <$buffer>\n"; 408 print "read $_[0] bytes: <$buffer>\n";
268 }; 409 };
269 410
270=item aio_move $srcpath, $dstpath, $callback->($status)
271
272Try to move the I<file> (directories not supported as either source or
273destination) from C<$srcpath> to C<$dstpath> and call the callback with
274the C<0> (error) or C<-1> ok.
275
276This is a composite request that tries to rename(2) the file first. If
277rename files with C<EXDEV>, it creates the destination file with mode 0200
278and copies the contents of the source file into it using C<aio_sendfile>,
279followed by restoring atime, mtime, access mode and uid/gid, in that
280order, and unlinking the C<$srcpath>.
281
282If an error occurs, the partial destination file will be unlinked, if
283possible, except when setting atime, mtime, access mode and uid/gid, where
284errors are being ignored.
285
286=cut
287
288sub aio_move($$$) {
289 my ($src, $dst, $cb) = @_;
290
291 my $pri = aioreq_pri;
292 my $grp = aio_group $cb;
293
294 aioreq_pri $pri;
295 add $grp aio_rename $src, $dst, sub {
296 if ($_[0] && $! == EXDEV) {
297 aioreq_pri $pri;
298 add $grp aio_open $src, O_RDONLY, 0, sub {
299 if (my $src_fh = $_[0]) {
300 my @stat = stat $src_fh;
301
302 aioreq_pri $pri;
303 add $grp aio_open $dst, O_WRONLY, 0200, sub {
304 if (my $dst_fh = $_[0]) {
305 aioreq_pri $pri;
306 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
307 close $src_fh;
308
309 if ($_[0] == $stat[7]) {
310 utime $stat[8], $stat[9], $dst;
311 chmod $stat[2] & 07777, $dst_fh;
312 chown $stat[4], $stat[5], $dst_fh;
313 close $dst_fh;
314
315 aioreq_pri $pri;
316 add $grp aio_unlink $src, sub {
317 $grp->result ($_[0]);
318 };
319 } else {
320 my $errno = $!;
321 aioreq_pri $pri;
322 add $grp aio_unlink $dst, sub {
323 $! = $errno;
324 $grp->result (-1);
325 };
326 }
327 };
328 } else {
329 $grp->result (-1);
330 }
331 },
332
333 } else {
334 $grp->result (-1);
335 }
336 };
337 } else {
338 $grp->result ($_[0]);
339 }
340 };
341
342 $grp
343}
344 411
345=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 412=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
346 413
347Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 414Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
348reading at byte offset C<$in_offset>, and starts writing at the current 415reading at byte offset C<$in_offset>, and starts writing at the current
… …
362C<$in_fh> than are written, and there is no way to find out how many 429C<$in_fh> than are written, and there is no way to find out how many
363bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 430bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
364provides the number of bytes written to C<$out_fh>. Only if the result 431provides the number of bytes written to C<$out_fh>. Only if the result
365value equals C<$length> one can assume that C<$length> bytes have been 432value equals C<$length> one can assume that C<$length> bytes have been
366read. 433read.
434
367 435
368=item aio_readahead $fh,$offset,$length, $callback->($retval) 436=item aio_readahead $fh,$offset,$length, $callback->($retval)
369 437
370C<aio_readahead> populates the page cache with data from a file so that 438C<aio_readahead> populates the page cache with data from a file so that
371subsequent reads from that file will not block on disk I/O. The C<$offset> 439subsequent reads from that file will not block on disk I/O. The C<$offset>
… …
377file. The current file offset of the file is left unchanged. 445file. The current file offset of the file is left unchanged.
378 446
379If that syscall doesn't exist (likely if your OS isn't Linux) it will be 447If that syscall doesn't exist (likely if your OS isn't Linux) it will be
380emulated by simply reading the data, which would have a similar effect. 448emulated by simply reading the data, which would have a similar effect.
381 449
450
382=item aio_stat $fh_or_path, $callback->($status) 451=item aio_stat $fh_or_path, $callback->($status)
383 452
384=item aio_lstat $fh, $callback->($status) 453=item aio_lstat $fh, $callback->($status)
385 454
386Works like perl's C<stat> or C<lstat> in void context. The callback will 455Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
399 aio_stat "/etc/passwd", sub { 468 aio_stat "/etc/passwd", sub {
400 $_[0] and die "stat failed: $!"; 469 $_[0] and die "stat failed: $!";
401 print "size is ", -s _, "\n"; 470 print "size is ", -s _, "\n";
402 }; 471 };
403 472
473
474=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
475
476Works like perl's C<utime> function (including the special case of $atime
477and $mtime being undef). Fractional times are supported if the underlying
478syscalls support them.
479
480When called with a pathname, uses utimes(2) if available, otherwise
481utime(2). If called on a file descriptor, uses futimes(2) if available,
482otherwise returns ENOSYS, so this is not portable.
483
484Examples:
485
486 # set atime and mtime to current time (basically touch(1)):
487 aio_utime "path", undef, undef;
488 # set atime to current time and mtime to beginning of the epoch:
489 aio_utime "path", time, undef; # undef==0
490
491
492=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
493
494Works like perl's C<chown> function, except that C<undef> for either $uid
495or $gid is being interpreted as "do not change" (but -1 can also be used).
496
497Examples:
498
499 # same as "chown root path" in the shell:
500 aio_chown "path", 0, -1;
501 # same as above:
502 aio_chown "path", 0, undef;
503
504
505=item aio_truncate $fh_or_path, $offset, $callback->($status)
506
507Works like truncate(2) or ftruncate(2).
508
509
510=item aio_chmod $fh_or_path, $mode, $callback->($status)
511
512Works like perl's C<chmod> function.
513
514
404=item aio_unlink $pathname, $callback->($status) 515=item aio_unlink $pathname, $callback->($status)
405 516
406Asynchronously unlink (delete) a file and call the callback with the 517Asynchronously unlink (delete) a file and call the callback with the
407result code. 518result code.
408 519
520
521=item aio_mknod $path, $mode, $dev, $callback->($status)
522
523[EXPERIMENTAL]
524
525Asynchronously create a device node (or fifo). See mknod(2).
526
527The only (POSIX-) portable way of calling this function is:
528
529 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
530
531
409=item aio_link $srcpath, $dstpath, $callback->($status) 532=item aio_link $srcpath, $dstpath, $callback->($status)
410 533
411Asynchronously create a new link to the existing object at C<$srcpath> at 534Asynchronously create a new link to the existing object at C<$srcpath> at
412the path C<$dstpath> and call the callback with the result code. 535the path C<$dstpath> and call the callback with the result code.
413 536
537
414=item aio_symlink $srcpath, $dstpath, $callback->($status) 538=item aio_symlink $srcpath, $dstpath, $callback->($status)
415 539
416Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 540Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
417the path C<$dstpath> and call the callback with the result code. 541the path C<$dstpath> and call the callback with the result code.
418 542
543
544=item aio_readlink $path, $callback->($link)
545
546Asynchronously read the symlink specified by C<$path> and pass it to
547the callback. If an error occurs, nothing or undef gets passed to the
548callback.
549
550
419=item aio_rename $srcpath, $dstpath, $callback->($status) 551=item aio_rename $srcpath, $dstpath, $callback->($status)
420 552
421Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 553Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422rename(2) and call the callback with the result code. 554rename(2) and call the callback with the result code.
423 555
556
557=item aio_mkdir $pathname, $mode, $callback->($status)
558
559Asynchronously mkdir (create) a directory and call the callback with
560the result code. C<$mode> will be modified by the umask at the time the
561request is executed, so do not change your umask.
562
563
424=item aio_rmdir $pathname, $callback->($status) 564=item aio_rmdir $pathname, $callback->($status)
425 565
426Asynchronously rmdir (delete) a directory and call the callback with the 566Asynchronously rmdir (delete) a directory and call the callback with the
427result code. 567result code.
568
428 569
429=item aio_readdir $pathname, $callback->($entries) 570=item aio_readdir $pathname, $callback->($entries)
430 571
431Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 572Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
432directory (i.e. opendir + readdir + closedir). The entries will not be 573directory (i.e. opendir + readdir + closedir). The entries will not be
433sorted, and will B<NOT> include the C<.> and C<..> entries. 574sorted, and will B<NOT> include the C<.> and C<..> entries.
434 575
435The callback a single argument which is either C<undef> or an array-ref 576The callback a single argument which is either C<undef> or an array-ref
436with the filenames. 577with the filenames.
578
579
580=item aio_load $path, $data, $callback->($status)
581
582This is a composite request that tries to fully load the given file into
583memory. Status is the same as with aio_read.
584
585=cut
586
587sub aio_load($$;$) {
588 aio_block {
589 my ($path, undef, $cb) = @_;
590 my $data = \$_[1];
591
592 my $pri = aioreq_pri;
593 my $grp = aio_group $cb;
594
595 aioreq_pri $pri;
596 add $grp aio_open $path, O_RDONLY, 0, sub {
597 my $fh = shift
598 or return $grp->result (-1);
599
600 aioreq_pri $pri;
601 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
602 $grp->result ($_[0]);
603 };
604 };
605
606 $grp
607 }
608}
609
610=item aio_copy $srcpath, $dstpath, $callback->($status)
611
612Try to copy the I<file> (directories not supported as either source or
613destination) from C<$srcpath> to C<$dstpath> and call the callback with
614the C<0> (error) or C<-1> ok.
615
616This is a composite request that it creates the destination file with
617mode 0200 and copies the contents of the source file into it using
618C<aio_sendfile>, followed by restoring atime, mtime, access mode and
619uid/gid, in that order.
620
621If an error occurs, the partial destination file will be unlinked, if
622possible, except when setting atime, mtime, access mode and uid/gid, where
623errors are being ignored.
624
625=cut
626
627sub aio_copy($$;$) {
628 aio_block {
629 my ($src, $dst, $cb) = @_;
630
631 my $pri = aioreq_pri;
632 my $grp = aio_group $cb;
633
634 aioreq_pri $pri;
635 add $grp aio_open $src, O_RDONLY, 0, sub {
636 if (my $src_fh = $_[0]) {
637 my @stat = stat $src_fh;
638
639 aioreq_pri $pri;
640 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
641 if (my $dst_fh = $_[0]) {
642 aioreq_pri $pri;
643 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
644 if ($_[0] == $stat[7]) {
645 $grp->result (0);
646 close $src_fh;
647
648 # those should not normally block. should. should.
649 utime $stat[8], $stat[9], $dst;
650 chmod $stat[2] & 07777, $dst_fh;
651 chown $stat[4], $stat[5], $dst_fh;
652 close $dst_fh;
653 } else {
654 $grp->result (-1);
655 close $src_fh;
656 close $dst_fh;
657
658 aioreq $pri;
659 add $grp aio_unlink $dst;
660 }
661 };
662 } else {
663 $grp->result (-1);
664 }
665 },
666
667 } else {
668 $grp->result (-1);
669 }
670 };
671
672 $grp
673 }
674}
675
676=item aio_move $srcpath, $dstpath, $callback->($status)
677
678Try to move the I<file> (directories not supported as either source or
679destination) from C<$srcpath> to C<$dstpath> and call the callback with
680the C<0> (error) or C<-1> ok.
681
682This is a composite request that tries to rename(2) the file first. If
683rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
684that is successful, unlinking the C<$srcpath>.
685
686=cut
687
688sub aio_move($$;$) {
689 aio_block {
690 my ($src, $dst, $cb) = @_;
691
692 my $pri = aioreq_pri;
693 my $grp = aio_group $cb;
694
695 aioreq_pri $pri;
696 add $grp aio_rename $src, $dst, sub {
697 if ($_[0] && $! == EXDEV) {
698 aioreq_pri $pri;
699 add $grp aio_copy $src, $dst, sub {
700 $grp->result ($_[0]);
701
702 if (!$_[0]) {
703 aioreq_pri $pri;
704 add $grp aio_unlink $src;
705 }
706 };
707 } else {
708 $grp->result ($_[0]);
709 }
710 };
711
712 $grp
713 }
714}
437 715
438=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 716=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439 717
440Scans a directory (similar to C<aio_readdir>) but additionally tries to 718Scans a directory (similar to C<aio_readdir>) but additionally tries to
441efficiently separate the entries of directory C<$path> into two sets of 719efficiently separate the entries of directory C<$path> into two sets of
… …
487as those tend to return 0 or 1 as link counts, which disables the 765as those tend to return 0 or 1 as link counts, which disables the
488directory counting heuristic. 766directory counting heuristic.
489 767
490=cut 768=cut
491 769
492sub aio_scandir($$$) { 770sub aio_scandir($$;$) {
771 aio_block {
493 my ($path, $maxreq, $cb) = @_; 772 my ($path, $maxreq, $cb) = @_;
494 773
495 my $pri = aioreq_pri; 774 my $pri = aioreq_pri;
496 775
497 my $grp = aio_group $cb; 776 my $grp = aio_group $cb;
498 777
499 $maxreq = 4 if $maxreq <= 0; 778 $maxreq = 4 if $maxreq <= 0;
500 779
501 # stat once 780 # stat once
502 aioreq_pri $pri;
503 add $grp aio_stat $path, sub {
504 return $grp->result () if $_[0];
505 my $now = time;
506 my $hash1 = join ":", (stat _)[0,1,3,7,9];
507
508 # read the directory entries
509 aioreq_pri $pri; 781 aioreq_pri $pri;
510 add $grp aio_readdir $path, sub { 782 add $grp aio_stat $path, sub {
511 my $entries = shift
512 or return $grp->result (); 783 return $grp->result () if $_[0];
784 my $now = time;
785 my $hash1 = join ":", (stat _)[0,1,3,7,9];
513 786
514 # stat the dir another time 787 # read the directory entries
515 aioreq_pri $pri; 788 aioreq_pri $pri;
789 add $grp aio_readdir $path, sub {
790 my $entries = shift
791 or return $grp->result ();
792
793 # stat the dir another time
794 aioreq_pri $pri;
516 add $grp aio_stat $path, sub { 795 add $grp aio_stat $path, sub {
517 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 796 my $hash2 = join ":", (stat _)[0,1,3,7,9];
518 797
519 my $ndirs; 798 my $ndirs;
520 799
521 # take the slow route if anything looks fishy 800 # take the slow route if anything looks fishy
522 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 801 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523 $ndirs = -1; 802 $ndirs = -1;
524 } else { 803 } else {
525 # if nlink == 2, we are finished 804 # if nlink == 2, we are finished
526 # on non-posix-fs's, we rely on nlink < 2 805 # on non-posix-fs's, we rely on nlink < 2
527 $ndirs = (stat _)[3] - 2 806 $ndirs = (stat _)[3] - 2
528 or return $grp->result ([], $entries); 807 or return $grp->result ([], $entries);
529 } 808 }
530 809
531 # sort into likely dirs and likely nondirs 810 # sort into likely dirs and likely nondirs
532 # dirs == files without ".", short entries first 811 # dirs == files without ".", short entries first
533 $entries = [map $_->[0], 812 $entries = [map $_->[0],
534 sort { $b->[1] cmp $a->[1] } 813 sort { $b->[1] cmp $a->[1] }
535 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 814 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
536 @$entries]; 815 @$entries];
537 816
538 my (@dirs, @nondirs); 817 my (@dirs, @nondirs);
539 818
540 my $statgrp = add $grp aio_group sub { 819 my $statgrp = add $grp aio_group sub {
541 $grp->result (\@dirs, \@nondirs); 820 $grp->result (\@dirs, \@nondirs);
542 }; 821 };
543 822
544 limit $statgrp $maxreq; 823 limit $statgrp $maxreq;
545 feed $statgrp sub { 824 feed $statgrp sub {
546 return unless @$entries; 825 return unless @$entries;
547 my $entry = pop @$entries; 826 my $entry = pop @$entries;
548 827
549 aioreq_pri $pri; 828 aioreq_pri $pri;
550 add $statgrp aio_stat "$path/$entry/.", sub { 829 add $statgrp aio_stat "$path/$entry/.", sub {
551 if ($_[0] < 0) { 830 if ($_[0] < 0) {
552 push @nondirs, $entry; 831 push @nondirs, $entry;
553 } else { 832 } else {
554 # need to check for real directory 833 # need to check for real directory
555 aioreq_pri $pri; 834 aioreq_pri $pri;
556 add $statgrp aio_lstat "$path/$entry", sub { 835 add $statgrp aio_lstat "$path/$entry", sub {
557 if (-d _) { 836 if (-d _) {
558 push @dirs, $entry; 837 push @dirs, $entry;
559 838
560 unless (--$ndirs) { 839 unless (--$ndirs) {
561 push @nondirs, @$entries; 840 push @nondirs, @$entries;
562 feed $statgrp; 841 feed $statgrp;
842 }
843 } else {
844 push @nondirs, $entry;
563 } 845 }
564 } else {
565 push @nondirs, $entry;
566 } 846 }
567 } 847 }
568 } 848 };
569 }; 849 };
570 }; 850 };
571 }; 851 };
572 }; 852 };
853
854 $grp
573 }; 855 }
856}
574 857
858=item aio_rmtree $path, $callback->($status)
859
860Delete a directory tree starting (and including) C<$path>, return the
861status of the final C<rmdir> only. This is a composite request that
862uses C<aio_scandir> to recurse into and rmdir directories, and unlink
863everything else.
864
865=cut
866
867sub aio_rmtree;
868sub aio_rmtree($;$) {
869 aio_block {
870 my ($path, $cb) = @_;
871
872 my $pri = aioreq_pri;
873 my $grp = aio_group $cb;
874
875 aioreq_pri $pri;
876 add $grp aio_scandir $path, 0, sub {
877 my ($dirs, $nondirs) = @_;
878
879 my $dirgrp = aio_group sub {
880 add $grp aio_rmdir $path, sub {
881 $grp->result ($_[0]);
882 };
883 };
884
885 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
886 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
887
888 add $grp $dirgrp;
889 };
890
575 $grp 891 $grp
892 }
576} 893}
577 894
578=item aio_fsync $fh, $callback->($status) 895=item aio_fsync $fh, $callback->($status)
579 896
580Asynchronously call fsync on the given filehandle and call the callback 897Asynchronously call fsync on the given filehandle and call the callback
… …
794 1111
795=back 1112=back
796 1113
797=head2 SUPPORT FUNCTIONS 1114=head2 SUPPORT FUNCTIONS
798 1115
1116=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1117
799=over 4 1118=over 4
800 1119
801=item $fileno = IO::AIO::poll_fileno 1120=item $fileno = IO::AIO::poll_fileno
802 1121
803Return the I<request result pipe file descriptor>. This filehandle must be 1122Return the I<request result pipe file descriptor>. This filehandle must be
… …
807 1126
808See C<poll_cb> for an example. 1127See C<poll_cb> for an example.
809 1128
810=item IO::AIO::poll_cb 1129=item IO::AIO::poll_cb
811 1130
812Process all outstanding events on the result pipe. You have to call this 1131Process some outstanding events on the result pipe. You have to call this
813regularly. Returns the number of events processed. Returns immediately 1132regularly. Returns the number of events processed. Returns immediately
814when no events are outstanding. 1133when no events are outstanding. The amount of events processed depends on
1134the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
815 1135
816If not all requests were processed for whatever reason, the filehandle 1136If not all requests were processed for whatever reason, the filehandle
817will still be ready when C<poll_cb> returns. 1137will still be ready when C<poll_cb> returns.
818 1138
819Example: Install an Event watcher that automatically calls 1139Example: Install an Event watcher that automatically calls
… …
821 1141
822 Event->io (fd => IO::AIO::poll_fileno, 1142 Event->io (fd => IO::AIO::poll_fileno,
823 poll => 'r', async => 1, 1143 poll => 'r', async => 1,
824 cb => \&IO::AIO::poll_cb); 1144 cb => \&IO::AIO::poll_cb);
825 1145
826=item IO::AIO::poll_some $max_requests 1146=item IO::AIO::max_poll_reqs $nreqs
827 1147
828Similar to C<poll_cb>, but only processes up to C<$max_requests> requests 1148=item IO::AIO::max_poll_time $seconds
829at a time.
830 1149
831Useful if you want to ensure some level of interactiveness when perl is 1150These set the maximum number of requests (default C<0>, meaning infinity)
832not fast enough to process all requests in time. 1151that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1152the maximum amount of time (default C<0>, meaning infinity) spent in
1153C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1154of time C<poll_cb> is allowed to use).
1155
1156Setting C<max_poll_time> to a non-zero value creates an overhead of one
1157syscall per request processed, which is not normally a problem unless your
1158callbacks are really really fast or your OS is really really slow (I am
1159not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1160
1161Setting these is useful if you want to ensure some level of
1162interactiveness when perl is not fast enough to process all requests in
1163time.
1164
1165For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833 1166
834Example: Install an Event watcher that automatically calls 1167Example: Install an Event watcher that automatically calls
835IO::AIO::poll_some with low priority, to ensure that other parts of the 1168IO::AIO::poll_cb with low priority, to ensure that other parts of the
836program get the CPU sometimes even under high AIO load. 1169program get the CPU sometimes even under high AIO load.
837 1170
1171 # try not to spend much more than 0.1s in poll_cb
1172 IO::AIO::max_poll_time 0.1;
1173
1174 # use a low priority so other tasks have priority
838 Event->io (fd => IO::AIO::poll_fileno, 1175 Event->io (fd => IO::AIO::poll_fileno,
839 poll => 'r', nice => 1, 1176 poll => 'r', nice => 1,
840 cb => sub { IO::AIO::poll_some 256 }); 1177 cb => &IO::AIO::poll_cb);
841 1178
842=item IO::AIO::poll_wait 1179=item IO::AIO::poll_wait
843 1180
1181If there are any outstanding requests and none of them in the result
844Wait till the result filehandle becomes ready for reading (simply does a 1182phase, wait till the result filehandle becomes ready for reading (simply
845C<select> on the filehandle. This is useful if you want to synchronously wait 1183does a C<select> on the filehandle. This is useful if you want to
846for some requests to finish). 1184synchronously wait for some requests to finish).
847 1185
848See C<nreqs> for an example. 1186See C<nreqs> for an example.
849 1187
1188=item IO::AIO::poll
1189
1190Waits until some requests have been handled.
1191
1192Returns the number of requests processed, but is otherwise strictly
1193equivalent to:
1194
1195 IO::AIO::poll_wait, IO::AIO::poll_cb
1196
850=item IO::AIO::nreqs 1197=item IO::AIO::flush
851 1198
852Returns the number of requests currently in the ready, execute or pending 1199Wait till all outstanding AIO requests have been handled.
853states (i.e. for which their callback has not been invoked yet).
854 1200
855Example: wait till there are no outstanding requests anymore: 1201Strictly equivalent to:
856 1202
857 IO::AIO::poll_wait, IO::AIO::poll_cb 1203 IO::AIO::poll_wait, IO::AIO::poll_cb
858 while IO::AIO::nreqs; 1204 while IO::AIO::nreqs;
859 1205
860=item IO::AIO::nready 1206=back
861 1207
862Returns the number of requests currently in the ready state (not yet 1208=head3 CONTROLLING THE NUMBER OF THREADS
863executed).
864 1209
865=item IO::AIO::npending 1210=over
866
867Returns the number of requests currently in the pending state (executed,
868but not yet processed by poll_cb).
869
870=item IO::AIO::flush
871
872Wait till all outstanding AIO requests have been handled.
873
874Strictly equivalent to:
875
876 IO::AIO::poll_wait, IO::AIO::poll_cb
877 while IO::AIO::nreqs;
878
879=item IO::AIO::poll
880
881Waits until some requests have been handled.
882
883Strictly equivalent to:
884
885 IO::AIO::poll_wait, IO::AIO::poll_cb
886 if IO::AIO::nreqs;
887 1211
888=item IO::AIO::min_parallel $nthreads 1212=item IO::AIO::min_parallel $nthreads
889 1213
890Set the minimum number of AIO threads to C<$nthreads>. The current 1214Set the minimum number of AIO threads to C<$nthreads>. The current
891default is C<8>, which means eight asynchronous operations can execute 1215default is C<8>, which means eight asynchronous operations can execute
892concurrently at any one time (the number of outstanding requests, 1216concurrently at any one time (the number of outstanding requests,
893however, is unlimited). 1217however, is unlimited).
894 1218
895IO::AIO starts threads only on demand, when an AIO request is queued and 1219IO::AIO starts threads only on demand, when an AIO request is queued and
896no free thread exists. 1220no free thread exists. Please note that queueing up a hundred requests can
1221create demand for a hundred threads, even if it turns out that everything
1222is in the cache and could have been processed faster by a single thread.
897 1223
898It is recommended to keep the number of threads relatively low, as some 1224It is recommended to keep the number of threads relatively low, as some
899Linux kernel versions will scale negatively with the number of threads 1225Linux kernel versions will scale negatively with the number of threads
900(higher parallelity => MUCH higher latency). With current Linux 2.6 1226(higher parallelity => MUCH higher latency). With current Linux 2.6
901versions, 4-32 threads should be fine. 1227versions, 4-32 threads should be fine.
… …
915This module automatically runs C<max_parallel 0> at program end, to ensure 1241This module automatically runs C<max_parallel 0> at program end, to ensure
916that all threads are killed and that there are no outstanding requests. 1242that all threads are killed and that there are no outstanding requests.
917 1243
918Under normal circumstances you don't need to call this function. 1244Under normal circumstances you don't need to call this function.
919 1245
1246=item IO::AIO::max_idle $nthreads
1247
1248Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1249threads that did not get a request to process within 10 seconds). That
1250means if a thread becomes idle while C<$nthreads> other threads are also
1251idle, it will free its resources and exit.
1252
1253This is useful when you allow a large number of threads (e.g. 100 or 1000)
1254to allow for extremely high load situations, but want to free resources
1255under normal circumstances (1000 threads can easily consume 30MB of RAM).
1256
1257The default is probably ok in most situations, especially if thread
1258creation is fast. If thread creation is very slow on your system you might
1259want to use larger values.
1260
920=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1261=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
921 1262
922This is a very bad function to use in interactive programs because it 1263This is a very bad function to use in interactive programs because it
923blocks, and a bad way to reduce concurrency because it is inexact: Better 1264blocks, and a bad way to reduce concurrency because it is inexact: Better
924use an C<aio_group> together with a feed callback. 1265use an C<aio_group> together with a feed callback.
925 1266
926Sets the maximum number of outstanding requests to C<$nreqs>. If you 1267Sets the maximum number of outstanding requests to C<$nreqs>. If you
927to queue up more than this number of requests, the next call to the 1268do queue up more than this number of requests, the next call to the
928C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>) 1269C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
929function will block until the limit is no longer exceeded. 1270function will block until the limit is no longer exceeded.
930 1271
931The default value is very large, so there is no practical limit on the 1272The default value is very large, so there is no practical limit on the
932number of outstanding requests. 1273number of outstanding requests.
… …
935C<max_oustsanding> is mainly useful in simple scripts (with low values) or 1276C<max_oustsanding> is mainly useful in simple scripts (with low values) or
936as a stop gap to shield against fatal memory overflow (with large values). 1277as a stop gap to shield against fatal memory overflow (with large values).
937 1278
938=back 1279=back
939 1280
1281=head3 STATISTICAL INFORMATION
1282
1283=over
1284
1285=item IO::AIO::nreqs
1286
1287Returns the number of requests currently in the ready, execute or pending
1288states (i.e. for which their callback has not been invoked yet).
1289
1290Example: wait till there are no outstanding requests anymore:
1291
1292 IO::AIO::poll_wait, IO::AIO::poll_cb
1293 while IO::AIO::nreqs;
1294
1295=item IO::AIO::nready
1296
1297Returns the number of requests currently in the ready state (not yet
1298executed).
1299
1300=item IO::AIO::npending
1301
1302Returns the number of requests currently in the pending state (executed,
1303but not yet processed by poll_cb).
1304
1305=back
1306
940=cut 1307=cut
941 1308
942# support function to convert a fd into a perl filehandle
943sub _fd2fh {
944 return undef if $_[0] < 0;
945
946 # try to generate nice filehandles
947 my $sym = "IO::AIO::fd#$_[0]";
948 local *$sym;
949
950 open *$sym, "+<&=$_[0]" # usually works under any unix
951 or open *$sym, "<&=$_[0]" # cygwin needs this
952 or open *$sym, ">&=$_[0]" # or this
953 or return undef;
954
955 *$sym
956}
957
958min_parallel 8; 1309min_parallel 8;
1310
1311END { flush }
959 1312
9601; 13131;
961 1314
962=head2 FORK BEHAVIOUR 1315=head2 FORK BEHAVIOUR
963 1316
… …
983bytes of memory. In addition, stat requests need a stat buffer (possibly 1336bytes of memory. In addition, stat requests need a stat buffer (possibly
984a few hundred bytes), readdir requires a result buffer and so on. Perl 1337a few hundred bytes), readdir requires a result buffer and so on. Perl
985scalars and other data passed into aio requests will also be locked and 1338scalars and other data passed into aio requests will also be locked and
986will consume memory till the request has entered the done state. 1339will consume memory till the request has entered the done state.
987 1340
988This is now awfully much, so queuing lots of requests is not usually a 1341This is not awfully much, so queuing lots of requests is not usually a
989problem. 1342problem.
990 1343
991Per-thread usage: 1344Per-thread usage:
992 1345
993In the execution phase, some aio requests require more memory for 1346In the execution phase, some aio requests require more memory for

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