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Revision 1.111 by root, Mon Aug 13 12:08:13 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;
124 187
125no warnings; 188no warnings;
126use strict 'vars'; 189use strict 'vars';
127 190
128use base 'Exporter'; 191use base 'Exporter';
129 192
130BEGIN { 193BEGIN {
131 our $VERSION = '2.0'; 194 our $VERSION = '2.4';
132 195
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 196 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 197 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 198 aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
136 aio_group aio_nop); 199 aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
200 aio_chown aio_chmod aio_utime aio_truncate);
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 201 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 202 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel nreqs nready npending); 203 min_parallel max_parallel max_idle
204 nreqs nready npending nthreads
205 max_poll_time max_poll_reqs);
140 206
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 207 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 208
143 require XSLoader; 209 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 210 XSLoader::load ("IO::AIO", $VERSION);
145} 211}
146 212
147=head1 FUNCTIONS 213=head1 FUNCTIONS
148 214
149=head2 AIO FUNCTIONS 215=head2 AIO REQUEST FUNCTIONS
150 216
151All the C<aio_*> calls are more or less thin wrappers around the syscall 217All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 218with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 219and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 220which must be a code reference. This code reference will get called with
… …
157syscall has been executed asynchronously. 223syscall has been executed asynchronously.
158 224
159All functions expecting a filehandle keep a copy of the filehandle 225All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 226internally until the request has finished.
161 227
162All requests return objects of type L<IO::AIO::REQ> that allow further 228All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 229further manipulation of those requests while they are in-flight.
164 230
165The pathnames you pass to these routines I<must> be absolute and 231The 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 232encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 233request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 234changed. Alternatively, you can make sure that you never change the
169current working directory. 235current working directory anywhere in the program and then use relative
236paths.
170 237
171To encode pathnames to byte form, either make sure you either: a) 238To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 239in 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 240tinkering, 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 241your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 242environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 243use something else to ensure your scalar has the correct contents.
244
245This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246handles correctly wether it is set or not.
177 247
178=over 4 248=over 4
179 249
180=item $prev_pri = aioreq_pri [$pri] 250=item $prev_pri = aioreq_pri [$pri]
181 251
… …
201 aio_read $_[0], ..., sub { 271 aio_read $_[0], ..., sub {
202 ... 272 ...
203 }; 273 };
204 }; 274 };
205 275
276
206=item aioreq_nice $pri_adjust 277=item aioreq_nice $pri_adjust
207 278
208Similar to C<aioreq_pri>, but subtracts the given value from the current 279Similar to C<aioreq_pri>, but subtracts the given value from the current
209priority, so effects are cumulative. 280priority, so the effect is cumulative.
281
210 282
211=item aio_open $pathname, $flags, $mode, $callback->($fh) 283=item aio_open $pathname, $flags, $mode, $callback->($fh)
212 284
213Asynchronously open or create a file and call the callback with a newly 285Asynchronously open or create a file and call the callback with a newly
214created filehandle for the file. 286created filehandle for the file.
… …
220list. They are the same as used by C<sysopen>. 292list. They are the same as used by C<sysopen>.
221 293
222Likewise, C<$mode> specifies the mode of the newly created file, if it 294Likewise, C<$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>, 295didn'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, 296except 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). 297and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
298by the umask in effect then the request is being executed, so better never
299change the umask.
226 300
227Example: 301Example:
228 302
229 aio_open "/etc/passwd", O_RDONLY, 0, sub { 303 aio_open "/etc/passwd", O_RDONLY, 0, sub {
230 if ($_[0]) { 304 if ($_[0]) {
… …
233 } else { 307 } else {
234 die "open failed: $!\n"; 308 die "open failed: $!\n";
235 } 309 }
236 }; 310 };
237 311
312
238=item aio_close $fh, $callback->($status) 313=item aio_close $fh, $callback->($status)
239 314
240Asynchronously close a file and call the callback with the result 315Asynchronously close a file and call the callback with the result
241code. I<WARNING:> although accepted, you should not pass in a perl 316code. I<WARNING:> although accepted, you should not pass in a perl
242filehandle here, as perl will likely close the file descriptor another 317filehandle here, as perl will likely close the file descriptor another
… …
244C<close> or just let filehandles go out of scope. 319C<close> or just let filehandles go out of scope.
245 320
246This is supposed to be a bug in the API, so that might change. It's 321This is supposed to be a bug in the API, so that might change. It's
247therefore best to avoid this function. 322therefore best to avoid this function.
248 323
324
249=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 325=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250 326
251=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 327=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252 328
253Reads or writes C<length> bytes from the specified C<fh> and C<offset> 329Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
254into the scalar given by C<data> and offset C<dataoffset> and calls the 330into the scalar given by C<$data> and offset C<$dataoffset> and calls the
255callback without the actual number of bytes read (or -1 on error, just 331callback without the actual number of bytes read (or -1 on error, just
256like the syscall). 332like the syscall).
257 333
334If C<$offset> is undefined, then the current file offset will be used (and
335updated), otherwise the file offset will not be changed by these calls.
336
337If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
338
339If C<$dataoffset> is less than zero, it will be counted from the end of
340C<$data>.
341
258The C<$data> scalar I<MUST NOT> be modified in any way while the request 342The C<$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 343is outstanding. Modifying it can result in segfaults or World War III (if
260necessary/optional hardware is installed). 344the necessary/optional hardware is installed).
261 345
262Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 346Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263offset C<0> within the scalar: 347offset C<0> within the scalar:
264 348
265 aio_read $fh, 7, 15, $buffer, 0, sub { 349 aio_read $fh, 7, 15, $buffer, 0, sub {
266 $_[0] > 0 or die "read error: $!"; 350 $_[0] > 0 or die "read error: $!";
267 print "read $_[0] bytes: <$buffer>\n"; 351 print "read $_[0] bytes: <$buffer>\n";
268 }; 352 };
269 353
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}
344 354
345=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 355=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
346 356
347Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 357Tries 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 358reading 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 372C<$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 373bytes 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 374provides 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 375value equals C<$length> one can assume that C<$length> bytes have been
366read. 376read.
377
367 378
368=item aio_readahead $fh,$offset,$length, $callback->($retval) 379=item aio_readahead $fh,$offset,$length, $callback->($retval)
369 380
370C<aio_readahead> populates the page cache with data from a file so that 381C<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> 382subsequent 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. 388file. The current file offset of the file is left unchanged.
378 389
379If that syscall doesn't exist (likely if your OS isn't Linux) it will be 390If 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. 391emulated by simply reading the data, which would have a similar effect.
381 392
393
382=item aio_stat $fh_or_path, $callback->($status) 394=item aio_stat $fh_or_path, $callback->($status)
383 395
384=item aio_lstat $fh, $callback->($status) 396=item aio_lstat $fh, $callback->($status)
385 397
386Works like perl's C<stat> or C<lstat> in void context. The callback will 398Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
399 aio_stat "/etc/passwd", sub { 411 aio_stat "/etc/passwd", sub {
400 $_[0] and die "stat failed: $!"; 412 $_[0] and die "stat failed: $!";
401 print "size is ", -s _, "\n"; 413 print "size is ", -s _, "\n";
402 }; 414 };
403 415
416
417=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
418
419Works like perl's C<utime> function (including the special case of $atime
420and $mtime being undef). Fractional times are supported if the underlying
421syscalls support them.
422
423When called with a pathname, uses utimes(2) if available, otherwise
424utime(2). If called on a file descriptor, uses futimes(2) if available,
425otherwise returns ENOSYS, so this is not portable.
426
427Examples:
428
429 # set atime and mtime to current time (basically touch(1)):
430 aio_utime "path", undef, undef;
431 # set atime to current time and mtime to beginning of the epoch:
432 aio_utime "path", time, undef; # undef==0
433
434
435=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
436
437Works like perl's C<chown> function, except that C<undef> for either $uid
438or $gid is being interpreted as "do not change" (but -1 can also be used).
439
440Examples:
441
442 # same as "chown root path" in the shell:
443 aio_chown "path", 0, -1;
444 # same as above:
445 aio_chown "path", 0, undef;
446
447
448=item aio_truncate $fh_or_path, $offset, $callback->($status)
449
450Works like truncate(2) or ftruncate(2).
451
452
453=item aio_chmod $fh_or_path, $mode, $callback->($status)
454
455Works like perl's C<chmod> function.
456
457
404=item aio_unlink $pathname, $callback->($status) 458=item aio_unlink $pathname, $callback->($status)
405 459
406Asynchronously unlink (delete) a file and call the callback with the 460Asynchronously unlink (delete) a file and call the callback with the
407result code. 461result code.
408 462
463
464=item aio_mknod $path, $mode, $dev, $callback->($status)
465
466[EXPERIMENTAL]
467
468Asynchronously create a device node (or fifo). See mknod(2).
469
470The only (POSIX-) portable way of calling this function is:
471
472 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
473
474
409=item aio_link $srcpath, $dstpath, $callback->($status) 475=item aio_link $srcpath, $dstpath, $callback->($status)
410 476
411Asynchronously create a new link to the existing object at C<$srcpath> at 477Asynchronously create a new link to the existing object at C<$srcpath> at
412the path C<$dstpath> and call the callback with the result code. 478the path C<$dstpath> and call the callback with the result code.
413 479
480
414=item aio_symlink $srcpath, $dstpath, $callback->($status) 481=item aio_symlink $srcpath, $dstpath, $callback->($status)
415 482
416Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 483Asynchronously 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. 484the path C<$dstpath> and call the callback with the result code.
418 485
486
487=item aio_readlink $path, $callback->($link)
488
489Asynchronously read the symlink specified by C<$path> and pass it to
490the callback. If an error occurs, nothing or undef gets passed to the
491callback.
492
493
419=item aio_rename $srcpath, $dstpath, $callback->($status) 494=item aio_rename $srcpath, $dstpath, $callback->($status)
420 495
421Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 496Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422rename(2) and call the callback with the result code. 497rename(2) and call the callback with the result code.
423 498
499
500=item aio_mkdir $pathname, $mode, $callback->($status)
501
502Asynchronously mkdir (create) a directory and call the callback with
503the result code. C<$mode> will be modified by the umask at the time the
504request is executed, so do not change your umask.
505
506
424=item aio_rmdir $pathname, $callback->($status) 507=item aio_rmdir $pathname, $callback->($status)
425 508
426Asynchronously rmdir (delete) a directory and call the callback with the 509Asynchronously rmdir (delete) a directory and call the callback with the
427result code. 510result code.
511
428 512
429=item aio_readdir $pathname, $callback->($entries) 513=item aio_readdir $pathname, $callback->($entries)
430 514
431Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 515Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
432directory (i.e. opendir + readdir + closedir). The entries will not be 516directory (i.e. opendir + readdir + closedir). The entries will not be
433sorted, and will B<NOT> include the C<.> and C<..> entries. 517sorted, and will B<NOT> include the C<.> and C<..> entries.
434 518
435The callback a single argument which is either C<undef> or an array-ref 519The callback a single argument which is either C<undef> or an array-ref
436with the filenames. 520with the filenames.
521
522
523=item aio_load $path, $data, $callback->($status)
524
525This is a composite request that tries to fully load the given file into
526memory. Status is the same as with aio_read.
527
528=cut
529
530sub aio_load($$;$) {
531 aio_block {
532 my ($path, undef, $cb) = @_;
533 my $data = \$_[1];
534
535 my $pri = aioreq_pri;
536 my $grp = aio_group $cb;
537
538 aioreq_pri $pri;
539 add $grp aio_open $path, O_RDONLY, 0, sub {
540 my $fh = shift
541 or return $grp->result (-1);
542
543 aioreq_pri $pri;
544 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
545 $grp->result ($_[0]);
546 };
547 };
548
549 $grp
550 }
551}
552
553=item aio_copy $srcpath, $dstpath, $callback->($status)
554
555Try to copy the I<file> (directories not supported as either source or
556destination) from C<$srcpath> to C<$dstpath> and call the callback with
557the C<0> (error) or C<-1> ok.
558
559This is a composite request that it creates the destination file with
560mode 0200 and copies the contents of the source file into it using
561C<aio_sendfile>, followed by restoring atime, mtime, access mode and
562uid/gid, in that order.
563
564If an error occurs, the partial destination file will be unlinked, if
565possible, except when setting atime, mtime, access mode and uid/gid, where
566errors are being ignored.
567
568=cut
569
570sub aio_copy($$;$) {
571 aio_block {
572 my ($src, $dst, $cb) = @_;
573
574 my $pri = aioreq_pri;
575 my $grp = aio_group $cb;
576
577 aioreq_pri $pri;
578 add $grp aio_open $src, O_RDONLY, 0, sub {
579 if (my $src_fh = $_[0]) {
580 my @stat = stat $src_fh;
581
582 aioreq_pri $pri;
583 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
584 if (my $dst_fh = $_[0]) {
585 aioreq_pri $pri;
586 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
587 if ($_[0] == $stat[7]) {
588 $grp->result (0);
589 close $src_fh;
590
591 # those should not normally block. should. should.
592 utime $stat[8], $stat[9], $dst;
593 chmod $stat[2] & 07777, $dst_fh;
594 chown $stat[4], $stat[5], $dst_fh;
595 close $dst_fh;
596 } else {
597 $grp->result (-1);
598 close $src_fh;
599 close $dst_fh;
600
601 aioreq $pri;
602 add $grp aio_unlink $dst;
603 }
604 };
605 } else {
606 $grp->result (-1);
607 }
608 },
609
610 } else {
611 $grp->result (-1);
612 }
613 };
614
615 $grp
616 }
617}
618
619=item aio_move $srcpath, $dstpath, $callback->($status)
620
621Try to move the I<file> (directories not supported as either source or
622destination) from C<$srcpath> to C<$dstpath> and call the callback with
623the C<0> (error) or C<-1> ok.
624
625This is a composite request that tries to rename(2) the file first. If
626rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
627that is successful, unlinking the C<$srcpath>.
628
629=cut
630
631sub aio_move($$;$) {
632 aio_block {
633 my ($src, $dst, $cb) = @_;
634
635 my $pri = aioreq_pri;
636 my $grp = aio_group $cb;
637
638 aioreq_pri $pri;
639 add $grp aio_rename $src, $dst, sub {
640 if ($_[0] && $! == EXDEV) {
641 aioreq_pri $pri;
642 add $grp aio_copy $src, $dst, sub {
643 $grp->result ($_[0]);
644
645 if (!$_[0]) {
646 aioreq_pri $pri;
647 add $grp aio_unlink $src;
648 }
649 };
650 } else {
651 $grp->result ($_[0]);
652 }
653 };
654
655 $grp
656 }
657}
437 658
438=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 659=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439 660
440Scans a directory (similar to C<aio_readdir>) but additionally tries to 661Scans a directory (similar to C<aio_readdir>) but additionally tries to
441efficiently separate the entries of directory C<$path> into two sets of 662efficiently separate the entries of directory C<$path> into two sets of
… …
487as those tend to return 0 or 1 as link counts, which disables the 708as those tend to return 0 or 1 as link counts, which disables the
488directory counting heuristic. 709directory counting heuristic.
489 710
490=cut 711=cut
491 712
492sub aio_scandir($$$) { 713sub aio_scandir($$;$) {
714 aio_block {
493 my ($path, $maxreq, $cb) = @_; 715 my ($path, $maxreq, $cb) = @_;
494 716
495 my $pri = aioreq_pri; 717 my $pri = aioreq_pri;
496 718
497 my $grp = aio_group $cb; 719 my $grp = aio_group $cb;
498 720
499 $maxreq = 4 if $maxreq <= 0; 721 $maxreq = 4 if $maxreq <= 0;
500 722
501 # stat once 723 # 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; 724 aioreq_pri $pri;
510 add $grp aio_readdir $path, sub { 725 add $grp aio_stat $path, sub {
511 my $entries = shift
512 or return $grp->result (); 726 return $grp->result () if $_[0];
727 my $now = time;
728 my $hash1 = join ":", (stat _)[0,1,3,7,9];
513 729
514 # stat the dir another time 730 # read the directory entries
515 aioreq_pri $pri; 731 aioreq_pri $pri;
732 add $grp aio_readdir $path, sub {
733 my $entries = shift
734 or return $grp->result ();
735
736 # stat the dir another time
737 aioreq_pri $pri;
516 add $grp aio_stat $path, sub { 738 add $grp aio_stat $path, sub {
517 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 739 my $hash2 = join ":", (stat _)[0,1,3,7,9];
518 740
519 my $ndirs; 741 my $ndirs;
520 742
521 # take the slow route if anything looks fishy 743 # take the slow route if anything looks fishy
522 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 744 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523 $ndirs = -1; 745 $ndirs = -1;
524 } else { 746 } else {
525 # if nlink == 2, we are finished 747 # if nlink == 2, we are finished
526 # on non-posix-fs's, we rely on nlink < 2 748 # on non-posix-fs's, we rely on nlink < 2
527 $ndirs = (stat _)[3] - 2 749 $ndirs = (stat _)[3] - 2
528 or return $grp->result ([], $entries); 750 or return $grp->result ([], $entries);
529 } 751 }
530 752
531 # sort into likely dirs and likely nondirs 753 # sort into likely dirs and likely nondirs
532 # dirs == files without ".", short entries first 754 # dirs == files without ".", short entries first
533 $entries = [map $_->[0], 755 $entries = [map $_->[0],
534 sort { $b->[1] cmp $a->[1] } 756 sort { $b->[1] cmp $a->[1] }
535 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 757 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
536 @$entries]; 758 @$entries];
537 759
538 my (@dirs, @nondirs); 760 my (@dirs, @nondirs);
539 761
540 my $statgrp = add $grp aio_group sub { 762 my $statgrp = add $grp aio_group sub {
541 $grp->result (\@dirs, \@nondirs); 763 $grp->result (\@dirs, \@nondirs);
542 }; 764 };
543 765
544 limit $statgrp $maxreq; 766 limit $statgrp $maxreq;
545 feed $statgrp sub { 767 feed $statgrp sub {
546 return unless @$entries; 768 return unless @$entries;
547 my $entry = pop @$entries; 769 my $entry = pop @$entries;
548 770
549 aioreq_pri $pri; 771 aioreq_pri $pri;
550 add $statgrp aio_stat "$path/$entry/.", sub { 772 add $statgrp aio_stat "$path/$entry/.", sub {
551 if ($_[0] < 0) { 773 if ($_[0] < 0) {
552 push @nondirs, $entry; 774 push @nondirs, $entry;
553 } else { 775 } else {
554 # need to check for real directory 776 # need to check for real directory
555 aioreq_pri $pri; 777 aioreq_pri $pri;
556 add $statgrp aio_lstat "$path/$entry", sub { 778 add $statgrp aio_lstat "$path/$entry", sub {
557 if (-d _) { 779 if (-d _) {
558 push @dirs, $entry; 780 push @dirs, $entry;
559 781
560 unless (--$ndirs) { 782 unless (--$ndirs) {
561 push @nondirs, @$entries; 783 push @nondirs, @$entries;
562 feed $statgrp; 784 feed $statgrp;
785 }
786 } else {
787 push @nondirs, $entry;
563 } 788 }
564 } else {
565 push @nondirs, $entry;
566 } 789 }
567 } 790 }
568 } 791 };
569 }; 792 };
570 }; 793 };
571 }; 794 };
572 }; 795 };
796
797 $grp
573 }; 798 }
799}
574 800
801=item aio_rmtree $path, $callback->($status)
802
803Delete a directory tree starting (and including) C<$path>, return the
804status of the final C<rmdir> only. This is a composite request that
805uses C<aio_scandir> to recurse into and rmdir directories, and unlink
806everything else.
807
808=cut
809
810sub aio_rmtree;
811sub aio_rmtree($;$) {
812 aio_block {
813 my ($path, $cb) = @_;
814
815 my $pri = aioreq_pri;
816 my $grp = aio_group $cb;
817
818 aioreq_pri $pri;
819 add $grp aio_scandir $path, 0, sub {
820 my ($dirs, $nondirs) = @_;
821
822 my $dirgrp = aio_group sub {
823 add $grp aio_rmdir $path, sub {
824 $grp->result ($_[0]);
825 };
826 };
827
828 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
829 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
830
831 add $grp $dirgrp;
832 };
833
575 $grp 834 $grp
835 }
576} 836}
577 837
578=item aio_fsync $fh, $callback->($status) 838=item aio_fsync $fh, $callback->($status)
579 839
580Asynchronously call fsync on the given filehandle and call the callback 840Asynchronously call fsync on the given filehandle and call the callback
… …
794 1054
795=back 1055=back
796 1056
797=head2 SUPPORT FUNCTIONS 1057=head2 SUPPORT FUNCTIONS
798 1058
1059=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1060
799=over 4 1061=over 4
800 1062
801=item $fileno = IO::AIO::poll_fileno 1063=item $fileno = IO::AIO::poll_fileno
802 1064
803Return the I<request result pipe file descriptor>. This filehandle must be 1065Return the I<request result pipe file descriptor>. This filehandle must be
… …
807 1069
808See C<poll_cb> for an example. 1070See C<poll_cb> for an example.
809 1071
810=item IO::AIO::poll_cb 1072=item IO::AIO::poll_cb
811 1073
812Process all outstanding events on the result pipe. You have to call this 1074Process some outstanding events on the result pipe. You have to call this
813regularly. Returns the number of events processed. Returns immediately 1075regularly. Returns the number of events processed. Returns immediately
814when no events are outstanding. 1076when no events are outstanding. The amount of events processed depends on
1077the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
815 1078
816If not all requests were processed for whatever reason, the filehandle 1079If not all requests were processed for whatever reason, the filehandle
817will still be ready when C<poll_cb> returns. 1080will still be ready when C<poll_cb> returns.
818 1081
819Example: Install an Event watcher that automatically calls 1082Example: Install an Event watcher that automatically calls
… …
821 1084
822 Event->io (fd => IO::AIO::poll_fileno, 1085 Event->io (fd => IO::AIO::poll_fileno,
823 poll => 'r', async => 1, 1086 poll => 'r', async => 1,
824 cb => \&IO::AIO::poll_cb); 1087 cb => \&IO::AIO::poll_cb);
825 1088
826=item IO::AIO::poll_some $max_requests 1089=item IO::AIO::max_poll_reqs $nreqs
827 1090
828Similar to C<poll_cb>, but only processes up to C<$max_requests> requests 1091=item IO::AIO::max_poll_time $seconds
829at a time.
830 1092
831Useful if you want to ensure some level of interactiveness when perl is 1093These set the maximum number of requests (default C<0>, meaning infinity)
832not fast enough to process all requests in time. 1094that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1095the maximum amount of time (default C<0>, meaning infinity) spent in
1096C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1097of time C<poll_cb> is allowed to use).
1098
1099Setting C<max_poll_time> to a non-zero value creates an overhead of one
1100syscall per request processed, which is not normally a problem unless your
1101callbacks are really really fast or your OS is really really slow (I am
1102not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1103
1104Setting these is useful if you want to ensure some level of
1105interactiveness when perl is not fast enough to process all requests in
1106time.
1107
1108For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833 1109
834Example: Install an Event watcher that automatically calls 1110Example: Install an Event watcher that automatically calls
835IO::AIO::poll_some with low priority, to ensure that other parts of the 1111IO::AIO::poll_cb with low priority, to ensure that other parts of the
836program get the CPU sometimes even under high AIO load. 1112program get the CPU sometimes even under high AIO load.
837 1113
1114 # try not to spend much more than 0.1s in poll_cb
1115 IO::AIO::max_poll_time 0.1;
1116
1117 # use a low priority so other tasks have priority
838 Event->io (fd => IO::AIO::poll_fileno, 1118 Event->io (fd => IO::AIO::poll_fileno,
839 poll => 'r', nice => 1, 1119 poll => 'r', nice => 1,
840 cb => sub { IO::AIO::poll_some 256 }); 1120 cb => &IO::AIO::poll_cb);
841 1121
842=item IO::AIO::poll_wait 1122=item IO::AIO::poll_wait
843 1123
1124If there are any outstanding requests and none of them in the result
844Wait till the result filehandle becomes ready for reading (simply does a 1125phase, wait till the result filehandle becomes ready for reading (simply
845C<select> on the filehandle. This is useful if you want to synchronously wait 1126does a C<select> on the filehandle. This is useful if you want to
846for some requests to finish). 1127synchronously wait for some requests to finish).
847 1128
848See C<nreqs> for an example. 1129See C<nreqs> for an example.
849 1130
1131=item IO::AIO::poll
1132
1133Waits until some requests have been handled.
1134
1135Returns the number of requests processed, but is otherwise strictly
1136equivalent to:
1137
1138 IO::AIO::poll_wait, IO::AIO::poll_cb
1139
850=item IO::AIO::nreqs 1140=item IO::AIO::flush
851 1141
852Returns the number of requests currently in the ready, execute or pending 1142Wait till all outstanding AIO requests have been handled.
853states (i.e. for which their callback has not been invoked yet).
854 1143
855Example: wait till there are no outstanding requests anymore: 1144Strictly equivalent to:
856 1145
857 IO::AIO::poll_wait, IO::AIO::poll_cb 1146 IO::AIO::poll_wait, IO::AIO::poll_cb
858 while IO::AIO::nreqs; 1147 while IO::AIO::nreqs;
859 1148
860=item IO::AIO::nready 1149=back
861 1150
862Returns the number of requests currently in the ready state (not yet 1151=head3 CONTROLLING THE NUMBER OF THREADS
863executed).
864 1152
865=item IO::AIO::npending 1153=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 1154
888=item IO::AIO::min_parallel $nthreads 1155=item IO::AIO::min_parallel $nthreads
889 1156
890Set the minimum number of AIO threads to C<$nthreads>. The current 1157Set the minimum number of AIO threads to C<$nthreads>. The current
891default is C<8>, which means eight asynchronous operations can execute 1158default is C<8>, which means eight asynchronous operations can execute
892concurrently at any one time (the number of outstanding requests, 1159concurrently at any one time (the number of outstanding requests,
893however, is unlimited). 1160however, is unlimited).
894 1161
895IO::AIO starts threads only on demand, when an AIO request is queued and 1162IO::AIO starts threads only on demand, when an AIO request is queued and
896no free thread exists. 1163no free thread exists. Please note that queueing up a hundred requests can
1164create demand for a hundred threads, even if it turns out that everything
1165is in the cache and could have been processed faster by a single thread.
897 1166
898It is recommended to keep the number of threads relatively low, as some 1167It is recommended to keep the number of threads relatively low, as some
899Linux kernel versions will scale negatively with the number of threads 1168Linux kernel versions will scale negatively with the number of threads
900(higher parallelity => MUCH higher latency). With current Linux 2.6 1169(higher parallelity => MUCH higher latency). With current Linux 2.6
901versions, 4-32 threads should be fine. 1170versions, 4-32 threads should be fine.
… …
915This module automatically runs C<max_parallel 0> at program end, to ensure 1184This module automatically runs C<max_parallel 0> at program end, to ensure
916that all threads are killed and that there are no outstanding requests. 1185that all threads are killed and that there are no outstanding requests.
917 1186
918Under normal circumstances you don't need to call this function. 1187Under normal circumstances you don't need to call this function.
919 1188
1189=item IO::AIO::max_idle $nthreads
1190
1191Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1192threads that did not get a request to process within 10 seconds). That
1193means if a thread becomes idle while C<$nthreads> other threads are also
1194idle, it will free its resources and exit.
1195
1196This is useful when you allow a large number of threads (e.g. 100 or 1000)
1197to allow for extremely high load situations, but want to free resources
1198under normal circumstances (1000 threads can easily consume 30MB of RAM).
1199
1200The default is probably ok in most situations, especially if thread
1201creation is fast. If thread creation is very slow on your system you might
1202want to use larger values.
1203
920=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1204=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
921 1205
922This is a very bad function to use in interactive programs because it 1206This 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 1207blocks, and a bad way to reduce concurrency because it is inexact: Better
924use an C<aio_group> together with a feed callback. 1208use an C<aio_group> together with a feed callback.
… …
935C<max_oustsanding> is mainly useful in simple scripts (with low values) or 1219C<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). 1220as a stop gap to shield against fatal memory overflow (with large values).
937 1221
938=back 1222=back
939 1223
1224=head3 STATISTICAL INFORMATION
1225
1226=over
1227
1228=item IO::AIO::nreqs
1229
1230Returns the number of requests currently in the ready, execute or pending
1231states (i.e. for which their callback has not been invoked yet).
1232
1233Example: wait till there are no outstanding requests anymore:
1234
1235 IO::AIO::poll_wait, IO::AIO::poll_cb
1236 while IO::AIO::nreqs;
1237
1238=item IO::AIO::nready
1239
1240Returns the number of requests currently in the ready state (not yet
1241executed).
1242
1243=item IO::AIO::npending
1244
1245Returns the number of requests currently in the pending state (executed,
1246but not yet processed by poll_cb).
1247
1248=back
1249
940=cut 1250=cut
941 1251
942# support function to convert a fd into a perl filehandle 1252# support function to convert a fd into a perl filehandle
943sub _fd2fh { 1253sub _fd2fh {
944 return undef if $_[0] < 0; 1254 return undef if $_[0] < 0;
… …
954 1264
955 *$sym 1265 *$sym
956} 1266}
957 1267
958min_parallel 8; 1268min_parallel 8;
1269
1270END { flush }
959 1271
9601; 12721;
961 1273
962=head2 FORK BEHAVIOUR 1274=head2 FORK BEHAVIOUR
963 1275
… …
983bytes of memory. In addition, stat requests need a stat buffer (possibly 1295bytes of memory. In addition, stat requests need a stat buffer (possibly
984a few hundred bytes), readdir requires a result buffer and so on. Perl 1296a 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 1297scalars and other data passed into aio requests will also be locked and
986will consume memory till the request has entered the done state. 1298will consume memory till the request has entered the done state.
987 1299
988This is now awfully much, so queuing lots of requests is not usually a 1300This is not awfully much, so queuing lots of requests is not usually a
989problem. 1301problem.
990 1302
991Per-thread usage: 1303Per-thread usage:
992 1304
993In the execution phase, some aio requests require more memory for 1305In the execution phase, some aio requests require more memory for

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