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Revision 1.75 by root, Tue Oct 24 20:10:26 2006 UTC vs.
Revision 1.96 by root, Fri Dec 22 04:05:50 2006 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 example
68sockets), using these functions on file descriptors that support
69nonblocking operation (again, sockets, pipes etc.) is very inefficient or
70might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
71for that (such as the L<Event|Event> module): IO::AIO will naturally fit
72into such an event loop itself.
55 73
56In this version, a number of threads are started that execute your 74In this version, a number of threads are started that execute your
57requests and signal their completion. You don't need thread support 75requests and signal their completion. You don't need thread support
58in perl, and the threads created by this module will not be visible 76in 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 77to perl. In the future, this module might make use of the native aio
60functions available on many operating systems. However, they are often 78functions available on many operating systems. However, they are often
61not well-supported or restricted (Linux doesn't allow them on normal 79not well-supported or restricted (GNU/Linux doesn't allow them on normal
62files currently, for example), and they would only support aio_read and 80files currently, for example), and they would only support aio_read and
63aio_write, so the remaining functionality would have to be implemented 81aio_write, so the remaining functionality would have to be implemented
64using threads anyway. 82using threads anyway.
65 83
66Although the module will work with in the presence of other (Perl-) 84Although the module will work with in the presence of other (Perl-)
67threads, it is currently not reentrant in any way, so use appropriate 85threads, it is currently not reentrant in any way, so use appropriate
68locking yourself, always call C<poll_cb> from within the same thread, or 86locking yourself, always call C<poll_cb> from within the same thread, or
69never call C<poll_cb> (or other C<aio_> functions) recursively. 87never call C<poll_cb> (or other C<aio_> functions) recursively.
70 88
89=head2 EXAMPLE
90
91This is a simple example that uses the Event module and loads
92F</etc/passwd> asynchronously:
93
94 use Fcntl;
95 use Event;
96 use IO::AIO;
97
98 # register the IO::AIO callback with Event
99 Event->io (fd => IO::AIO::poll_fileno,
100 poll => 'r',
101 cb => \&IO::AIO::poll_cb);
102
103 # queue the request to open /etc/passwd
104 aio_open "/etc/passwd", O_RDONLY, 0, sub {
105 my $fh = shift
106 or die "error while opening: $!";
107
108 # stat'ing filehandles is generally non-blocking
109 my $size = -s $fh;
110
111 # queue a request to read the file
112 my $contents;
113 aio_read $fh, 0, $size, $contents, 0, sub {
114 $_[0] == $size
115 or die "short read: $!";
116
117 close $fh;
118
119 # file contents now in $contents
120 print $contents;
121
122 # exit event loop and program
123 Event::unloop;
124 };
125 };
126
127 # possibly queue up other requests, or open GUI windows,
128 # check for sockets etc. etc.
129
130 # process events as long as there are some:
131 Event::loop;
132
71=head1 REQUEST ANATOMY AND LIFETIME 133=head1 REQUEST ANATOMY AND LIFETIME
72 134
73Every C<aio_*> function creates a request. which is a C data structure not 135Every C<aio_*> function creates a request. which is a C data structure not
74directly visible to Perl. 136directly visible to Perl.
75 137
… …
116Request has reached the end of its lifetime and holds no resources anymore 178Request 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 179(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 180aio request is severed and calling its methods will either do nothing or
119result in a runtime error). 181result in a runtime error).
120 182
183=back
184
121=cut 185=cut
122 186
123package IO::AIO; 187package IO::AIO;
124 188
125no warnings; 189no warnings;
126use strict 'vars'; 190use strict 'vars';
127 191
128use base 'Exporter'; 192use base 'Exporter';
129 193
130BEGIN { 194BEGIN {
131 our $VERSION = '2.0'; 195 our $VERSION = '2.21';
132 196
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 197 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 198 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 199 aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
136 aio_group aio_nop); 200 aio_move aio_copy aio_group aio_nop aio_mknod);
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 max_outstanding nreqs); 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 aioreq_pri $pri 250=item $prev_pri = aioreq_pri [$pri]
181 251
182Sets the priority for the next aio request. The default priority 252Returns the priority value that would be used for the next request and, if
253C<$pri> is given, sets the priority for the next aio request.
254
183is C<0>, the minimum and maximum priorities are C<-4> and C<4>, 255The default priority is C<0>, the minimum and maximum priorities are C<-4>
184respectively. Requests with higher priority will be serviced first. 256and C<4>, respectively. Requests with higher priority will be serviced
257first.
185 258
186The priority will be reset to C<0> after each call to one of the C<aio_> 259The priority will be reset to C<0> after each call to one of the C<aio_*>
187functions. 260functions.
188 261
189Example: open a file with low priority, then read something from it with 262Example: open a file with low priority, then read something from it with
190higher priority so the read request is serviced before other low priority 263higher priority so the read request is serviced before other low priority
191open requests (potentially spamming the cache): 264open requests (potentially spamming the cache):
… …
201 }; 274 };
202 275
203=item aioreq_nice $pri_adjust 276=item aioreq_nice $pri_adjust
204 277
205Similar to C<aioreq_pri>, but subtracts the given value from the current 278Similar to C<aioreq_pri>, but subtracts the given value from the current
206priority, so effects are cumulative. 279priority, so the effect is cumulative.
207 280
208=item aio_open $pathname, $flags, $mode, $callback->($fh) 281=item aio_open $pathname, $flags, $mode, $callback->($fh)
209 282
210Asynchronously open or create a file and call the callback with a newly 283Asynchronously open or create a file and call the callback with a newly
211created filehandle for the file. 284created filehandle for the file.
… …
262 aio_read $fh, 7, 15, $buffer, 0, sub { 335 aio_read $fh, 7, 15, $buffer, 0, sub {
263 $_[0] > 0 or die "read error: $!"; 336 $_[0] > 0 or die "read error: $!";
264 print "read $_[0] bytes: <$buffer>\n"; 337 print "read $_[0] bytes: <$buffer>\n";
265 }; 338 };
266 339
267=item aio_move $srcpath, $dstpath, $callback->($status)
268
269Try to move the I<file> (directories not supported as either source or
270destination) from C<$srcpath> to C<$dstpath> and call the callback with
271the C<0> (error) or C<-1> ok.
272
273This is a composite request that tries to rename(2) the file first. If
274rename files with C<EXDEV>, it creates the destination file with mode 0200
275and copies the contents of the source file into it using C<aio_sendfile>,
276followed by restoring atime, mtime, access mode and uid/gid, in that
277order, and unlinking the C<$srcpath>.
278
279If an error occurs, the partial destination file will be unlinked, if
280possible, except when setting atime, mtime, access mode and uid/gid, where
281errors are being ignored.
282
283=cut
284
285sub aio_move($$$) {
286 my ($src, $dst, $cb) = @_;
287
288 my $grp = aio_group $cb;
289
290 add $grp aio_rename $src, $dst, sub {
291 if ($_[0] && $! == EXDEV) {
292 add $grp aio_open $src, O_RDONLY, 0, sub {
293 if (my $src_fh = $_[0]) {
294 my @stat = stat $src_fh;
295
296 add $grp aio_open $dst, O_WRONLY, 0200, sub {
297 if (my $dst_fh = $_[0]) {
298 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
299 close $src_fh;
300
301 if ($_[0] == $stat[7]) {
302 utime $stat[8], $stat[9], $dst;
303 chmod $stat[2] & 07777, $dst_fh;
304 chown $stat[4], $stat[5], $dst_fh;
305 close $dst_fh;
306
307 add $grp aio_unlink $src, sub {
308 $grp->result ($_[0]);
309 };
310 } else {
311 my $errno = $!;
312 add $grp aio_unlink $dst, sub {
313 $! = $errno;
314 $grp->result (-1);
315 };
316 }
317 };
318 } else {
319 $grp->result (-1);
320 }
321 },
322
323 } else {
324 $grp->result (-1);
325 }
326 };
327 } else {
328 $grp->result ($_[0]);
329 }
330 };
331
332 $grp
333}
334
335=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 340=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
336 341
337Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 342Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
338reading at byte offset C<$in_offset>, and starts writing at the current 343reading at byte offset C<$in_offset>, and starts writing at the current
339file offset of C<$out_fh>. Because of that, it is not safe to issue more 344file offset of C<$out_fh>. Because of that, it is not safe to issue more
… …
394=item aio_unlink $pathname, $callback->($status) 399=item aio_unlink $pathname, $callback->($status)
395 400
396Asynchronously unlink (delete) a file and call the callback with the 401Asynchronously unlink (delete) a file and call the callback with the
397result code. 402result code.
398 403
404=item aio_mknod $path, $mode, $dev, $callback->($status)
405
406[EXPERIMENTAL]
407
408Asynchronously create a device node (or fifo). See mknod(2).
409
410The only (POSIX-) portable way of calling this function is:
411
412 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
413
399=item aio_link $srcpath, $dstpath, $callback->($status) 414=item aio_link $srcpath, $dstpath, $callback->($status)
400 415
401Asynchronously create a new link to the existing object at C<$srcpath> at 416Asynchronously create a new link to the existing object at C<$srcpath> at
402the path C<$dstpath> and call the callback with the result code. 417the path C<$dstpath> and call the callback with the result code.
403 418
404=item aio_symlink $srcpath, $dstpath, $callback->($status) 419=item aio_symlink $srcpath, $dstpath, $callback->($status)
405 420
406Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 421Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
407the path C<$dstpath> and call the callback with the result code. 422the path C<$dstpath> and call the callback with the result code.
423
424=item aio_readlink $path, $callback->($link)
425
426Asynchronously read the symlink specified by C<$path> and pass it to
427the callback. If an error occurs, nothing or undef gets passed to the
428callback.
408 429
409=item aio_rename $srcpath, $dstpath, $callback->($status) 430=item aio_rename $srcpath, $dstpath, $callback->($status)
410 431
411Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 432Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
412rename(2) and call the callback with the result code. 433rename(2) and call the callback with the result code.
… …
423sorted, and will B<NOT> include the C<.> and C<..> entries. 444sorted, and will B<NOT> include the C<.> and C<..> entries.
424 445
425The callback a single argument which is either C<undef> or an array-ref 446The callback a single argument which is either C<undef> or an array-ref
426with the filenames. 447with the filenames.
427 448
449=item aio_copy $srcpath, $dstpath, $callback->($status)
450
451Try to copy the I<file> (directories not supported as either source or
452destination) from C<$srcpath> to C<$dstpath> and call the callback with
453the C<0> (error) or C<-1> ok.
454
455This is a composite request that it creates the destination file with
456mode 0200 and copies the contents of the source file into it using
457C<aio_sendfile>, followed by restoring atime, mtime, access mode and
458uid/gid, in that order.
459
460If an error occurs, the partial destination file will be unlinked, if
461possible, except when setting atime, mtime, access mode and uid/gid, where
462errors are being ignored.
463
464=cut
465
466sub aio_copy($$;$) {
467 aio_block {
468 my ($src, $dst, $cb) = @_;
469
470 my $pri = aioreq_pri;
471 my $grp = aio_group $cb;
472
473 aioreq_pri $pri;
474 add $grp aio_open $src, O_RDONLY, 0, sub {
475 if (my $src_fh = $_[0]) {
476 my @stat = stat $src_fh;
477
478 aioreq_pri $pri;
479 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
480 if (my $dst_fh = $_[0]) {
481 aioreq_pri $pri;
482 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
483 if ($_[0] == $stat[7]) {
484 $grp->result (0);
485 close $src_fh;
486
487 # those should not normally block. should. should.
488 utime $stat[8], $stat[9], $dst;
489 chmod $stat[2] & 07777, $dst_fh;
490 chown $stat[4], $stat[5], $dst_fh;
491 close $dst_fh;
492 } else {
493 $grp->result (-1);
494 close $src_fh;
495 close $dst_fh;
496
497 aioreq $pri;
498 add $grp aio_unlink $dst;
499 }
500 };
501 } else {
502 $grp->result (-1);
503 }
504 },
505
506 } else {
507 $grp->result (-1);
508 }
509 };
510
511 $grp
512 }
513}
514
515=item aio_move $srcpath, $dstpath, $callback->($status)
516
517Try to move the I<file> (directories not supported as either source or
518destination) from C<$srcpath> to C<$dstpath> and call the callback with
519the C<0> (error) or C<-1> ok.
520
521This is a composite request that tries to rename(2) the file first. If
522rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
523that is successful, unlinking the C<$srcpath>.
524
525=cut
526
527sub aio_move($$;$) {
528 aio_block {
529 my ($src, $dst, $cb) = @_;
530
531 my $pri = aioreq_pri;
532 my $grp = aio_group $cb;
533
534 aioreq_pri $pri;
535 add $grp aio_rename $src, $dst, sub {
536 if ($_[0] && $! == EXDEV) {
537 aioreq_pri $pri;
538 add $grp aio_copy $src, $dst, sub {
539 $grp->result ($_[0]);
540
541 if (!$_[0]) {
542 aioreq_pri $pri;
543 add $grp aio_unlink $src;
544 }
545 };
546 } else {
547 $grp->result ($_[0]);
548 }
549 };
550
551 $grp
552 }
553}
554
428=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 555=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429 556
430Scans a directory (similar to C<aio_readdir>) but additionally tries to 557Scans a directory (similar to C<aio_readdir>) but additionally tries to
431separate the entries of directory C<$path> into two sets of names, ones 558efficiently separate the entries of directory C<$path> into two sets of
432you can recurse into (directories or links to them), and ones you cannot 559names, directories you can recurse into (directories), and ones you cannot
433recurse into (everything else). 560recurse into (everything else, including symlinks to directories).
434 561
435C<aio_scandir> is a composite request that creates of many sub requests_ 562C<aio_scandir> is a composite request that creates of many sub requests_
436C<$maxreq> specifies the maximum number of outstanding aio requests that 563C<$maxreq> specifies the maximum number of outstanding aio requests that
437this function generates. If it is C<< <= 0 >>, then a suitable default 564this function generates. If it is C<< <= 0 >>, then a suitable default
438will be chosen (currently 6). 565will be chosen (currently 4).
439 566
440On error, the callback is called without arguments, otherwise it receives 567On error, the callback is called without arguments, otherwise it receives
441two array-refs with path-relative entry names. 568two array-refs with path-relative entry names.
442 569
443Example: 570Example:
… …
478directory counting heuristic. 605directory counting heuristic.
479 606
480=cut 607=cut
481 608
482sub aio_scandir($$$) { 609sub aio_scandir($$$) {
610 aio_block {
483 my ($path, $maxreq, $cb) = @_; 611 my ($path, $maxreq, $cb) = @_;
484 612
613 my $pri = aioreq_pri;
614
485 my $grp = aio_group $cb; 615 my $grp = aio_group $cb;
486 616
487 $maxreq = 6 if $maxreq <= 0; 617 $maxreq = 4 if $maxreq <= 0;
488 618
489 # stat once 619 # stat once
620 aioreq_pri $pri;
490 add $grp aio_stat $path, sub { 621 add $grp aio_stat $path, sub {
491 return $grp->result () if $_[0]; 622 return $grp->result () if $_[0];
492 my $now = time; 623 my $now = time;
493 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 624 my $hash1 = join ":", (stat _)[0,1,3,7,9];
494 625
495 # read the directory entries 626 # read the directory entries
627 aioreq_pri $pri;
496 add $grp aio_readdir $path, sub { 628 add $grp aio_readdir $path, sub {
497 my $entries = shift 629 my $entries = shift
498 or return $grp->result (); 630 or return $grp->result ();
499 631
500 # stat the dir another time 632 # stat the dir another time
633 aioreq_pri $pri;
501 add $grp aio_stat $path, sub { 634 add $grp aio_stat $path, sub {
502 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 635 my $hash2 = join ":", (stat _)[0,1,3,7,9];
503 636
504 my $ndirs; 637 my $ndirs;
505 638
506 # take the slow route if anything looks fishy 639 # take the slow route if anything looks fishy
507 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 640 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508 $ndirs = -1; 641 $ndirs = -1;
509 } else { 642 } else {
510 # if nlink == 2, we are finished 643 # if nlink == 2, we are finished
511 # on non-posix-fs's, we rely on nlink < 2 644 # on non-posix-fs's, we rely on nlink < 2
512 $ndirs = (stat _)[3] - 2 645 $ndirs = (stat _)[3] - 2
513 or return $grp->result ([], $entries); 646 or return $grp->result ([], $entries);
514 } 647 }
515 648
516 # sort into likely dirs and likely nondirs 649 # sort into likely dirs and likely nondirs
517 # dirs == files without ".", short entries first 650 # dirs == files without ".", short entries first
518 $entries = [map $_->[0], 651 $entries = [map $_->[0],
519 sort { $b->[1] cmp $a->[1] } 652 sort { $b->[1] cmp $a->[1] }
520 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 653 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
521 @$entries]; 654 @$entries];
522 655
523 my (@dirs, @nondirs); 656 my (@dirs, @nondirs);
524 657
525 my $statgrp = add $grp aio_group sub { 658 my $statgrp = add $grp aio_group sub {
526 $grp->result (\@dirs, \@nondirs); 659 $grp->result (\@dirs, \@nondirs);
527 }; 660 };
528 661
529 limit $statgrp $maxreq; 662 limit $statgrp $maxreq;
530 feed $statgrp sub { 663 feed $statgrp sub {
531 return unless @$entries; 664 return unless @$entries;
532 my $entry = pop @$entries; 665 my $entry = pop @$entries;
533 666
667 aioreq_pri $pri;
534 add $statgrp aio_stat "$path/$entry/.", sub { 668 add $statgrp aio_stat "$path/$entry/.", sub {
535 if ($_[0] < 0) { 669 if ($_[0] < 0) {
536 push @nondirs, $entry; 670 push @nondirs, $entry;
537 } else { 671 } else {
538 # need to check for real directory 672 # need to check for real directory
673 aioreq_pri $pri;
539 add $statgrp aio_lstat "$path/$entry", sub { 674 add $statgrp aio_lstat "$path/$entry", sub {
540 if (-d _) { 675 if (-d _) {
541 push @dirs, $entry; 676 push @dirs, $entry;
542 677
543 unless (--$ndirs) { 678 unless (--$ndirs) {
544 push @nondirs, @$entries; 679 push @nondirs, @$entries;
545 feed $statgrp; 680 feed $statgrp;
681 }
682 } else {
683 push @nondirs, $entry;
546 } 684 }
547 } else {
548 push @nondirs, $entry;
549 } 685 }
550 } 686 }
551 } 687 };
552 }; 688 };
553 }; 689 };
554 }; 690 };
555 }; 691 };
692
693 $grp
556 }; 694 }
557
558 $grp
559} 695}
560 696
561=item aio_fsync $fh, $callback->($status) 697=item aio_fsync $fh, $callback->($status)
562 698
563Asynchronously call fsync on the given filehandle and call the callback 699Asynchronously call fsync on the given filehandle and call the callback
… …
682=item * They can also can also be added to other IO::AIO::GRP objects. 818=item * They can also can also be added to other IO::AIO::GRP objects.
683 819
684=item * You must not add requests to a group from within the group callback (or 820=item * You must not add requests to a group from within the group callback (or
685any later time). 821any later time).
686 822
687=item * This does not harmonise well with C<max_outstanding>, so best do
688not combine C<aio_group> with it. Groups and feeders are recommended for
689this kind of concurrency-limiting.
690
691=back 823=back
692 824
693Their lifetime, simplified, looks like this: when they are empty, they 825Their lifetime, simplified, looks like this: when they are empty, they
694will finish very quickly. If they contain only requests that are in the 826will finish very quickly. If they contain only requests that are in the
695C<done> state, they will also finish. Otherwise they will continue to 827C<done> state, they will also finish. Otherwise they will continue to
… …
718itself. Useful when you queued a lot of events but got a result early. 850itself. Useful when you queued a lot of events but got a result early.
719 851
720=item $grp->result (...) 852=item $grp->result (...)
721 853
722Set the result value(s) that will be passed to the group callback when all 854Set the result value(s) that will be passed to the group callback when all
723subrequests have finished. By default, no argument will be passed. 855subrequests have finished and set thre groups errno to the current value
856of errno (just like calling C<errno> without an error number). By default,
857no argument will be passed and errno is zero.
858
859=item $grp->errno ([$errno])
860
861Sets the group errno value to C<$errno>, or the current value of errno
862when the argument is missing.
863
864Every aio request has an associated errno value that is restored when
865the callback is invoked. This method lets you change this value from its
866default (0).
867
868Calling C<result> will also set errno, so make sure you either set C<$!>
869before the call to C<result>, or call c<errno> after it.
724 870
725=item feed $grp $callback->($grp) 871=item feed $grp $callback->($grp)
726 872
727Sets a feeder/generator on this group: every group can have an attached 873Sets a feeder/generator on this group: every group can have an attached
728generator that generates requests if idle. The idea behind this is that, 874generator that generates requests if idle. The idea behind this is that,
… …
767 913
768=back 914=back
769 915
770=head2 SUPPORT FUNCTIONS 916=head2 SUPPORT FUNCTIONS
771 917
918=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
919
772=over 4 920=over 4
773 921
774=item $fileno = IO::AIO::poll_fileno 922=item $fileno = IO::AIO::poll_fileno
775 923
776Return the I<request result pipe file descriptor>. This filehandle must be 924Return the I<request result pipe file descriptor>. This filehandle must be
… …
780 928
781See C<poll_cb> for an example. 929See C<poll_cb> for an example.
782 930
783=item IO::AIO::poll_cb 931=item IO::AIO::poll_cb
784 932
785Process all outstanding events on the result pipe. You have to call this 933Process some outstanding events on the result pipe. You have to call this
786regularly. Returns the number of events processed. Returns immediately 934regularly. Returns the number of events processed. Returns immediately
787when no events are outstanding. 935when no events are outstanding. The amount of events processed depends on
936the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
937
938If not all requests were processed for whatever reason, the filehandle
939will still be ready when C<poll_cb> returns.
788 940
789Example: Install an Event watcher that automatically calls 941Example: Install an Event watcher that automatically calls
790IO::AIO::poll_cb with high priority: 942IO::AIO::poll_cb with high priority:
791 943
792 Event->io (fd => IO::AIO::poll_fileno, 944 Event->io (fd => IO::AIO::poll_fileno,
793 poll => 'r', async => 1, 945 poll => 'r', async => 1,
794 cb => \&IO::AIO::poll_cb); 946 cb => \&IO::AIO::poll_cb);
795 947
948=item IO::AIO::max_poll_reqs $nreqs
949
950=item IO::AIO::max_poll_time $seconds
951
952These set the maximum number of requests (default C<0>, meaning infinity)
953that are being processed by C<IO::AIO::poll_cb> in one call, respectively
954the maximum amount of time (default C<0>, meaning infinity) spent in
955C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
956of time C<poll_cb> is allowed to use).
957
958Setting C<max_poll_time> to a non-zero value creates an overhead of one
959syscall per request processed, which is not normally a problem unless your
960callbacks are really really fast or your OS is really really slow (I am
961not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
962
963Setting these is useful if you want to ensure some level of
964interactiveness when perl is not fast enough to process all requests in
965time.
966
967For interactive programs, values such as C<0.01> to C<0.1> should be fine.
968
969Example: Install an Event watcher that automatically calls
970IO::AIO::poll_cb with low priority, to ensure that other parts of the
971program get the CPU sometimes even under high AIO load.
972
973 # try not to spend much more than 0.1s in poll_cb
974 IO::AIO::max_poll_time 0.1;
975
976 # use a low priority so other tasks have priority
977 Event->io (fd => IO::AIO::poll_fileno,
978 poll => 'r', nice => 1,
979 cb => &IO::AIO::poll_cb);
980
796=item IO::AIO::poll_wait 981=item IO::AIO::poll_wait
797 982
983If there are any outstanding requests and none of them in the result
798Wait till the result filehandle becomes ready for reading (simply does a 984phase, wait till the result filehandle becomes ready for reading (simply
799C<select> on the filehandle. This is useful if you want to synchronously wait 985does a C<select> on the filehandle. This is useful if you want to
800for some requests to finish). 986synchronously wait for some requests to finish).
801 987
802See C<nreqs> for an example. 988See C<nreqs> for an example.
803 989
990=item IO::AIO::poll
991
992Waits until some requests have been handled.
993
994Returns the number of requests processed, but is otherwise strictly
995equivalent to:
996
997 IO::AIO::poll_wait, IO::AIO::poll_cb
998
804=item IO::AIO::nreqs 999=item IO::AIO::flush
805 1000
806Returns the number of requests currently outstanding (i.e. for which their 1001Wait till all outstanding AIO requests have been handled.
807callback has not been invoked yet).
808 1002
809Example: wait till there are no outstanding requests anymore: 1003Strictly equivalent to:
810 1004
811 IO::AIO::poll_wait, IO::AIO::poll_cb 1005 IO::AIO::poll_wait, IO::AIO::poll_cb
812 while IO::AIO::nreqs; 1006 while IO::AIO::nreqs;
813 1007
814=item IO::AIO::flush 1008=head3 CONTROLLING THE NUMBER OF THREADS
815
816Wait till all outstanding AIO requests have been handled.
817
818Strictly equivalent to:
819
820 IO::AIO::poll_wait, IO::AIO::poll_cb
821 while IO::AIO::nreqs;
822
823=item IO::AIO::poll
824
825Waits until some requests have been handled.
826
827Strictly equivalent to:
828
829 IO::AIO::poll_wait, IO::AIO::poll_cb
830 if IO::AIO::nreqs;
831 1009
832=item IO::AIO::min_parallel $nthreads 1010=item IO::AIO::min_parallel $nthreads
833 1011
834Set the minimum number of AIO threads to C<$nthreads>. The current 1012Set the minimum number of AIO threads to C<$nthreads>. The current
835default is C<8>, which means eight asynchronous operations can execute 1013default is C<8>, which means eight asynchronous operations can execute
836concurrently at any one time (the number of outstanding requests, 1014concurrently at any one time (the number of outstanding requests,
837however, is unlimited). 1015however, is unlimited).
838 1016
839IO::AIO starts threads only on demand, when an AIO request is queued and 1017IO::AIO starts threads only on demand, when an AIO request is queued and
840no free thread exists. 1018no free thread exists. Please note that queueing up a hundred requests can
1019create demand for a hundred threads, even if it turns out that everything
1020is in the cache and could have been processed faster by a single thread.
841 1021
842It is recommended to keep the number of threads relatively low, as some 1022It is recommended to keep the number of threads relatively low, as some
843Linux kernel versions will scale negatively with the number of threads 1023Linux kernel versions will scale negatively with the number of threads
844(higher parallelity => MUCH higher latency). With current Linux 2.6 1024(higher parallelity => MUCH higher latency). With current Linux 2.6
845versions, 4-32 threads should be fine. 1025versions, 4-32 threads should be fine.
… …
859This module automatically runs C<max_parallel 0> at program end, to ensure 1039This module automatically runs C<max_parallel 0> at program end, to ensure
860that all threads are killed and that there are no outstanding requests. 1040that all threads are killed and that there are no outstanding requests.
861 1041
862Under normal circumstances you don't need to call this function. 1042Under normal circumstances you don't need to call this function.
863 1043
1044=item IO::AIO::max_idle $nthreads
1045
1046Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1047threads that did not get a request to process within 10 seconds). That
1048means if a thread becomes idle while C<$nthreads> other threads are also
1049idle, it will free its resources and exit.
1050
1051This is useful when you allow a large number of threads (e.g. 100 or 1000)
1052to allow for extremely high load situations, but want to free resources
1053under normal circumstances (1000 threads can easily consume 30MB of RAM).
1054
1055The default is probably ok in most situations, especially if thread
1056creation is fast. If thread creation is very slow on your system you might
1057want to use larger values.
1058
864=item $oldnreqs = IO::AIO::max_outstanding $nreqs 1059=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
865 1060
866[DEPRECATED] 1061This is a very bad function to use in interactive programs because it
1062blocks, and a bad way to reduce concurrency because it is inexact: Better
1063use an C<aio_group> together with a feed callback.
867 1064
868Sets the maximum number of outstanding requests to C<$nreqs>. If you 1065Sets the maximum number of outstanding requests to C<$nreqs>. If you
869try to queue up more than this number of requests, the caller will block until 1066to queue up more than this number of requests, the next call to the
870some requests have been handled. 1067C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1068function will block until the limit is no longer exceeded.
871 1069
872The default is very large, so normally there is no practical limit. If you 1070The default value is very large, so there is no practical limit on the
873queue up many requests in a loop it often improves speed if you set 1071number of outstanding requests.
874this to a relatively low number, such as C<100>.
875 1072
876This function does not work well together with C<aio_group>'s, and their 1073You can still queue as many requests as you want. Therefore,
877feeder interface is better suited to limiting concurrency, so do not use 1074C<max_oustsanding> is mainly useful in simple scripts (with low values) or
878this function. 1075as a stop gap to shield against fatal memory overflow (with large values).
879 1076
880Under normal circumstances you don't need to call this function. 1077=head3 STATISTICAL INFORMATION
1078
1079=item IO::AIO::nreqs
1080
1081Returns the number of requests currently in the ready, execute or pending
1082states (i.e. for which their callback has not been invoked yet).
1083
1084Example: wait till there are no outstanding requests anymore:
1085
1086 IO::AIO::poll_wait, IO::AIO::poll_cb
1087 while IO::AIO::nreqs;
1088
1089=item IO::AIO::nready
1090
1091Returns the number of requests currently in the ready state (not yet
1092executed).
1093
1094=item IO::AIO::npending
1095
1096Returns the number of requests currently in the pending state (executed,
1097but not yet processed by poll_cb).
881 1098
882=back 1099=back
883 1100
884=cut 1101=cut
885 1102
… …
899 *$sym 1116 *$sym
900} 1117}
901 1118
902min_parallel 8; 1119min_parallel 8;
903 1120
904END { 1121END { flush }
905 max_parallel 0;
906}
907 1122
9081; 11231;
909 1124
910=head2 FORK BEHAVIOUR 1125=head2 FORK BEHAVIOUR
911 1126

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