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Revision 1.99 by root, Sun Jan 7 21:32:20 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
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.
55 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.
73
56Currently, a number of threads are started that execute your read/writes 74In this version, a number of threads are started that execute your
57and signal their completion. You don't need thread support in perl, and 75requests and signal their completion. You don't need thread support
58the threads created by this module will not be visible to perl. In the 76in perl, and the threads created by this module will not be visible
59future, this module might make use of the native aio functions available 77to perl. In the future, this module might make use of the native aio
60on many operating systems. However, they are often not well-supported 78functions available on many operating systems. However, they are often
61(Linux doesn't allow them on normal files currently, for example), 79not well-supported or restricted (GNU/Linux doesn't allow them on normal
62and they would only support aio_read and aio_write, so the remaining 80files currently, for example), and they would only support aio_read and
63functionality would have to be implemented using threads anyway. 81aio_write, so the remaining functionality would have to be implemented
82using threads anyway.
64 83
65Although the module will work with in the presence of other threads, 84Although the module will work with in the presence of other (Perl-)
66it is currently not reentrant in any way, so use appropriate locking 85threads, it is currently not reentrant in any way, so use appropriate
67yourself, always call C<poll_cb> from within the same thread, or never 86locking yourself, always call C<poll_cb> from within the same thread, or
68call C<poll_cb> (or other C<aio_> functions) recursively. 87never call C<poll_cb> (or other C<aio_> functions) recursively.
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
133=head1 REQUEST ANATOMY AND LIFETIME
134
135Every C<aio_*> function creates a request. which is a C data structure not
136directly visible to Perl.
137
138If called in non-void context, every request function returns a Perl
139object representing the request. In void context, nothing is returned,
140which saves a bit of memory.
141
142The perl object is a fairly standard ref-to-hash object. The hash contents
143are not used by IO::AIO so you are free to store anything you like in it.
144
145During their existance, aio requests travel through the following states,
146in order:
147
148=over 4
149
150=item ready
151
152Immediately after a request is created it is put into the ready state,
153waiting for a thread to execute it.
154
155=item execute
156
157A thread has accepted the request for processing and is currently
158executing it (e.g. blocking in read).
159
160=item pending
161
162The request has been executed and is waiting for result processing.
163
164While request submission and execution is fully asynchronous, result
165processing is not and relies on the perl interpreter calling C<poll_cb>
166(or another function with the same effect).
167
168=item result
169
170The request results are processed synchronously by C<poll_cb>.
171
172The C<poll_cb> function will process all outstanding aio requests by
173calling their callbacks, freeing memory associated with them and managing
174any groups they are contained in.
175
176=item done
177
178Request has reached the end of its lifetime and holds no resources anymore
179(except possibly for the Perl object, but its connection to the actual
180aio request is severed and calling its methods will either do nothing or
181result in a runtime error).
182
183=back
69 184
70=cut 185=cut
71 186
72package IO::AIO; 187package IO::AIO;
73 188
75use strict 'vars'; 190use strict 'vars';
76 191
77use base 'Exporter'; 192use base 'Exporter';
78 193
79BEGIN { 194BEGIN {
80 our $VERSION = '2.0'; 195 our $VERSION = '2.32';
81 196
82 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
83 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
84 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
85 aio_group aio_nop); 200 aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree);
86 our @EXPORT = (@AIO_REQ, qw(aioreq_pri)); 201 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
87 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 202 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88 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);
89 206
90 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 207 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91 208
92 require XSLoader; 209 require XSLoader;
93 XSLoader::load ("IO::AIO", $VERSION); 210 XSLoader::load ("IO::AIO", $VERSION);
94} 211}
95 212
96=head1 FUNCTIONS 213=head1 FUNCTIONS
97 214
98=head2 AIO FUNCTIONS 215=head2 AIO REQUEST FUNCTIONS
99 216
100All the C<aio_*> calls are more or less thin wrappers around the syscall 217All the C<aio_*> calls are more or less thin wrappers around the syscall
101with the same name (sans C<aio_>). The arguments are similar or identical, 218with the same name (sans C<aio_>). The arguments are similar or identical,
102and they all accept an additional (and optional) C<$callback> argument 219and they all accept an additional (and optional) C<$callback> argument
103which 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
106syscall has been executed asynchronously. 223syscall has been executed asynchronously.
107 224
108All functions expecting a filehandle keep a copy of the filehandle 225All functions expecting a filehandle keep a copy of the filehandle
109internally until the request has finished. 226internally until the request has finished.
110 227
111All 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
112manipulation of those requests while they are in-flight. 229further manipulation of those requests while they are in-flight.
113 230
114The pathnames you pass to these routines I<must> be absolute and 231The pathnames you pass to these routines I<must> be absolute and
115encoded 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
116request is being executed, the current working directory could have 233request is being executed, the current working directory could have
117changed. Alternatively, you can make sure that you never change the 234changed. Alternatively, you can make sure that you never change the
118current working directory. 235current working directory anywhere in the program and then use relative
236paths.
119 237
120To encode pathnames to byte form, either make sure you either: a) 238To encode pathnames as octets, either make sure you either: a) always pass
121always pass in filenames you got from outside (command line, readdir 239in filenames you got from outside (command line, readdir etc.) without
122etc.), 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
123your 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
124environment, d) use Glib::filename_from_unicode on unicode filenames or e) 242environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125use 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.
126 247
127=over 4 248=over 4
128 249
129=item aioreq_pri $pri 250=item $prev_pri = aioreq_pri [$pri]
130 251
131Sets 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
132is 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>
133respectively. Requests with higher priority will be serviced first. 256and C<4>, respectively. Requests with higher priority will be serviced
257first.
134 258
135The 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_*>
136functions. 260functions.
137 261
138Example: 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
139higher priority so the read request is serviced before other low priority 263higher priority so the read request is serviced before other low priority
140open requests (potentially spamming the cache): 264open requests (potentially spamming the cache):
150 }; 274 };
151 275
152=item aioreq_nice $pri_adjust 276=item aioreq_nice $pri_adjust
153 277
154Similar 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
155priority, so effects are cumulative. 279priority, so the effect is cumulative.
156 280
157=item aio_open $pathname, $flags, $mode, $callback->($fh) 281=item aio_open $pathname, $flags, $mode, $callback->($fh)
158 282
159Asynchronously 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
160created filehandle for the file. 284created filehandle for the file.
211 aio_read $fh, 7, 15, $buffer, 0, sub { 335 aio_read $fh, 7, 15, $buffer, 0, sub {
212 $_[0] > 0 or die "read error: $!"; 336 $_[0] > 0 or die "read error: $!";
213 print "read $_[0] bytes: <$buffer>\n"; 337 print "read $_[0] bytes: <$buffer>\n";
214 }; 338 };
215 339
216=item aio_move $srcpath, $dstpath, $callback->($status)
217
218[EXPERIMENTAL due to internal aio_group use]
219
220Try to move the I<file> (directories not supported as either source or
221destination) from C<$srcpath> to C<$dstpath> and call the callback with
222the C<0> (error) or C<-1> ok.
223
224This is a composite request that tries to rename(2) the file first. If
225rename files with C<EXDEV>, it creates the destination file with mode 0200
226and copies the contents of the source file into it using C<aio_sendfile>,
227followed by restoring atime, mtime, access mode and uid/gid, in that
228order, and unlinking the C<$srcpath>.
229
230If an error occurs, the partial destination file will be unlinked, if
231possible, except when setting atime, mtime, access mode and uid/gid, where
232errors are being ignored.
233
234=cut
235
236sub aio_move($$$) {
237 my ($src, $dst, $cb) = @_;
238
239 my $grp = aio_group $cb;
240
241 add $grp aio_rename $src, $dst, sub {
242 if ($_[0] && $! == EXDEV) {
243 add $grp aio_open $src, O_RDONLY, 0, sub {
244 if (my $src_fh = $_[0]) {
245 my @stat = stat $src_fh;
246
247 add $grp aio_open $dst, O_WRONLY, 0200, sub {
248 if (my $dst_fh = $_[0]) {
249 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
250 close $src_fh;
251
252 if ($_[0] == $stat[7]) {
253 utime $stat[8], $stat[9], $dst;
254 chmod $stat[2] & 07777, $dst_fh;
255 chown $stat[4], $stat[5], $dst_fh;
256 close $dst_fh;
257
258 add $grp aio_unlink $src, sub {
259 $grp->result ($_[0]);
260 };
261 } else {
262 my $errno = $!;
263 add $grp aio_unlink $dst, sub {
264 $! = $errno;
265 $grp->result (-1);
266 };
267 }
268 };
269 } else {
270 $grp->result (-1);
271 }
272 },
273
274 } else {
275 $grp->result (-1);
276 }
277 };
278 } else {
279 $grp->result ($_[0]);
280 }
281 };
282
283 $grp
284}
285
286=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)
287 341
288Tries 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
289reading 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
290file 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
345=item aio_unlink $pathname, $callback->($status) 399=item aio_unlink $pathname, $callback->($status)
346 400
347Asynchronously unlink (delete) a file and call the callback with the 401Asynchronously unlink (delete) a file and call the callback with the
348result code. 402result code.
349 403
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
350=item aio_link $srcpath, $dstpath, $callback->($status) 414=item aio_link $srcpath, $dstpath, $callback->($status)
351 415
352Asynchronously 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
353the path C<$dstpath> and call the callback with the result code. 417the path C<$dstpath> and call the callback with the result code.
354 418
355=item aio_symlink $srcpath, $dstpath, $callback->($status) 419=item aio_symlink $srcpath, $dstpath, $callback->($status)
356 420
357Asynchronously 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
358the 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.
359 429
360=item aio_rename $srcpath, $dstpath, $callback->($status) 430=item aio_rename $srcpath, $dstpath, $callback->($status)
361 431
362Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 432Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363rename(2) and call the callback with the result code. 433rename(2) and call the callback with the result code.
374sorted, and will B<NOT> include the C<.> and C<..> entries. 444sorted, and will B<NOT> include the C<.> and C<..> entries.
375 445
376The 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
377with the filenames. 447with the filenames.
378 448
449=item aio_load $path, $data, $callback->($status)
450
451This is a composite request that tries to fully load the given file into
452memory. Status is the same as with aio_read.
453
454=cut
455
456sub aio_load($$;$) {
457 aio_block {
458 my ($path, undef, $cb) = @_;
459 my $data = \$_[1];
460
461 my $pri = aioreq_pri;
462 my $grp = aio_group $cb;
463
464 aioreq_pri $pri;
465 add $grp aio_open $path, O_RDONLY, 0, sub {
466 my ($fh) = @_
467 or return $grp->result (-1);
468
469 aioreq_pri $pri;
470 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
471 $grp->result ($_[0]);
472 };
473 };
474
475 $grp
476 }
477}
478
479=item aio_copy $srcpath, $dstpath, $callback->($status)
480
481Try to copy the I<file> (directories not supported as either source or
482destination) from C<$srcpath> to C<$dstpath> and call the callback with
483the C<0> (error) or C<-1> ok.
484
485This is a composite request that it creates the destination file with
486mode 0200 and copies the contents of the source file into it using
487C<aio_sendfile>, followed by restoring atime, mtime, access mode and
488uid/gid, in that order.
489
490If an error occurs, the partial destination file will be unlinked, if
491possible, except when setting atime, mtime, access mode and uid/gid, where
492errors are being ignored.
493
494=cut
495
496sub aio_copy($$;$) {
497 aio_block {
498 my ($src, $dst, $cb) = @_;
499
500 my $pri = aioreq_pri;
501 my $grp = aio_group $cb;
502
503 aioreq_pri $pri;
504 add $grp aio_open $src, O_RDONLY, 0, sub {
505 if (my $src_fh = $_[0]) {
506 my @stat = stat $src_fh;
507
508 aioreq_pri $pri;
509 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
510 if (my $dst_fh = $_[0]) {
511 aioreq_pri $pri;
512 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
513 if ($_[0] == $stat[7]) {
514 $grp->result (0);
515 close $src_fh;
516
517 # those should not normally block. should. should.
518 utime $stat[8], $stat[9], $dst;
519 chmod $stat[2] & 07777, $dst_fh;
520 chown $stat[4], $stat[5], $dst_fh;
521 close $dst_fh;
522 } else {
523 $grp->result (-1);
524 close $src_fh;
525 close $dst_fh;
526
527 aioreq $pri;
528 add $grp aio_unlink $dst;
529 }
530 };
531 } else {
532 $grp->result (-1);
533 }
534 },
535
536 } else {
537 $grp->result (-1);
538 }
539 };
540
541 $grp
542 }
543}
544
545=item aio_move $srcpath, $dstpath, $callback->($status)
546
547Try to move the I<file> (directories not supported as either source or
548destination) from C<$srcpath> to C<$dstpath> and call the callback with
549the C<0> (error) or C<-1> ok.
550
551This is a composite request that tries to rename(2) the file first. If
552rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
553that is successful, unlinking the C<$srcpath>.
554
555=cut
556
557sub aio_move($$;$) {
558 aio_block {
559 my ($src, $dst, $cb) = @_;
560
561 my $pri = aioreq_pri;
562 my $grp = aio_group $cb;
563
564 aioreq_pri $pri;
565 add $grp aio_rename $src, $dst, sub {
566 if ($_[0] && $! == EXDEV) {
567 aioreq_pri $pri;
568 add $grp aio_copy $src, $dst, sub {
569 $grp->result ($_[0]);
570
571 if (!$_[0]) {
572 aioreq_pri $pri;
573 add $grp aio_unlink $src;
574 }
575 };
576 } else {
577 $grp->result ($_[0]);
578 }
579 };
580
581 $grp
582 }
583}
584
379=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 585=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380 586
381[EXPERIMENTAL due to internal aio_group use]
382
383Scans a directory (similar to C<aio_readdir>) but additionally tries to 587Scans a directory (similar to C<aio_readdir>) but additionally tries to
384separate the entries of directory C<$path> into two sets of names, ones 588efficiently separate the entries of directory C<$path> into two sets of
385you can recurse into (directories or links to them), and ones you cannot 589names, directories you can recurse into (directories), and ones you cannot
386recurse into (everything else). 590recurse into (everything else, including symlinks to directories).
387 591
388C<aio_scandir> is a composite request that creates of many sub requests_ 592C<aio_scandir> is a composite request that creates of many sub requests_
389C<$maxreq> specifies the maximum number of outstanding aio requests that 593C<$maxreq> specifies the maximum number of outstanding aio requests that
390this function generates. If it is C<< <= 0 >>, then a suitable default 594this function generates. If it is C<< <= 0 >>, then a suitable default
391will be chosen (currently 6). 595will be chosen (currently 4).
392 596
393On error, the callback is called without arguments, otherwise it receives 597On error, the callback is called without arguments, otherwise it receives
394two array-refs with path-relative entry names. 598two array-refs with path-relative entry names.
395 599
396Example: 600Example:
431directory counting heuristic. 635directory counting heuristic.
432 636
433=cut 637=cut
434 638
435sub aio_scandir($$$) { 639sub aio_scandir($$$) {
640 aio_block {
436 my ($path, $maxreq, $cb) = @_; 641 my ($path, $maxreq, $cb) = @_;
437 642
643 my $pri = aioreq_pri;
644
438 my $grp = aio_group $cb; 645 my $grp = aio_group $cb;
439 646
440 $maxreq = 6 if $maxreq <= 0; 647 $maxreq = 4 if $maxreq <= 0;
441 648
442 # stat once 649 # stat once
650 aioreq_pri $pri;
443 add $grp aio_stat $path, sub { 651 add $grp aio_stat $path, sub {
444 return $grp->result () if $_[0]; 652 return $grp->result () if $_[0];
445 my $now = time; 653 my $now = time;
446 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 654 my $hash1 = join ":", (stat _)[0,1,3,7,9];
447 655
448 # read the directory entries 656 # read the directory entries
657 aioreq_pri $pri;
449 add $grp aio_readdir $path, sub { 658 add $grp aio_readdir $path, sub {
450 my $entries = shift 659 my $entries = shift
451 or return $grp->result (); 660 or return $grp->result ();
452 661
453 # stat the dir another time 662 # stat the dir another time
663 aioreq_pri $pri;
454 add $grp aio_stat $path, sub { 664 add $grp aio_stat $path, sub {
455 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 665 my $hash2 = join ":", (stat _)[0,1,3,7,9];
456 666
457 my $ndirs; 667 my $ndirs;
458 668
459 # take the slow route if anything looks fishy 669 # take the slow route if anything looks fishy
460 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 670 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
461 $ndirs = -1; 671 $ndirs = -1;
462 } else { 672 } else {
463 # if nlink == 2, we are finished 673 # if nlink == 2, we are finished
464 # on non-posix-fs's, we rely on nlink < 2 674 # on non-posix-fs's, we rely on nlink < 2
465 $ndirs = (stat _)[3] - 2 675 $ndirs = (stat _)[3] - 2
466 or return $grp->result ([], $entries); 676 or return $grp->result ([], $entries);
467 } 677 }
468 678
469 # sort into likely dirs and likely nondirs 679 # sort into likely dirs and likely nondirs
470 # dirs == files without ".", short entries first 680 # dirs == files without ".", short entries first
471 $entries = [map $_->[0], 681 $entries = [map $_->[0],
472 sort { $b->[1] cmp $a->[1] } 682 sort { $b->[1] cmp $a->[1] }
473 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 683 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474 @$entries]; 684 @$entries];
475 685
476 my (@dirs, @nondirs); 686 my (@dirs, @nondirs);
477 687
478 my ($statcb, $schedcb);
479 my $nreq = 0;
480
481 my $statgrp = add $grp aio_group; 688 my $statgrp = add $grp aio_group sub {
482
483 $schedcb = sub {
484 if (@$entries) {
485 if ($nreq < $maxreq) {
486 my $ent = pop @$entries;
487 $nreq++;
488 add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489 }
490 } elsif (!$nreq) {
491 # finished
492 $statgrp->cancel;
493 undef $statcb;
494 undef $schedcb;
495 $grp->result (\@dirs, \@nondirs); 689 $grp->result (\@dirs, \@nondirs);
496 } 690 };
691
692 limit $statgrp $maxreq;
693 feed $statgrp sub {
694 return unless @$entries;
695 my $entry = pop @$entries;
696
697 aioreq_pri $pri;
698 add $statgrp aio_stat "$path/$entry/.", sub {
699 if ($_[0] < 0) {
700 push @nondirs, $entry;
701 } else {
702 # need to check for real directory
703 aioreq_pri $pri;
704 add $statgrp aio_lstat "$path/$entry", sub {
705 if (-d _) {
706 push @dirs, $entry;
707
708 unless (--$ndirs) {
709 push @nondirs, @$entries;
710 feed $statgrp;
711 }
712 } else {
713 push @nondirs, $entry;
714 }
715 }
716 }
717 };
718 };
497 }; 719 };
498 $statcb = sub {
499 my ($status, $entry) = @_;
500
501 if ($status < 0) {
502 $nreq--;
503 push @nondirs, $entry;
504 &$schedcb;
505 } else {
506 # need to check for real directory
507 add $grp aio_lstat "$path/$entry", sub {
508 $nreq--;
509
510 if (-d _) {
511 push @dirs, $entry;
512
513 if (!--$ndirs) {
514 push @nondirs, @$entries;
515 $entries = [];
516 }
517 } else {
518 push @nondirs, $entry;
519 }
520
521 &$schedcb;
522 }
523 }
524 };
525
526 &$schedcb while @$entries && $nreq < $maxreq;
527 }; 720 };
528 }; 721 };
722
723 $grp
529 }; 724 }
725}
530 726
727=item aio_rmtree $path, $callback->($status)
728
729Delete a directory tree starting (and including) C<$path>, return the status of the final C<rmdir> only.
730This is a composite request that uses C<aio_scandir> to recurse into and rmdir directories, and
731unlink everything else.
732
733=cut
734
735sub aio_rmtree;
736sub aio_rmtree {
737 aio_block {
738 my ($path, $cb) = @_;
739
740 my $pri = aioreq_pri;
741 my $grp = aio_group $cb;
742
743 aioreq_pri $pri;
744 add $grp aio_scandir $path, 0, sub {
745 my ($dirs, $nondirs) = @_;
746
747 my $dirgrp = aio_group sub {
748 add $grp aio_rmdir $path, sub {
749 $grp->result ($_[0]);
750 };
751 };
752
753 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
754 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
755
756 add $grp $dirgrp;
757 };
758
531 $grp 759 $grp
760 }
532} 761}
533 762
534=item aio_fsync $fh, $callback->($status) 763=item aio_fsync $fh, $callback->($status)
535 764
536Asynchronously call fsync on the given filehandle and call the callback 765Asynchronously call fsync on the given filehandle and call the callback
544If this call isn't available because your OS lacks it or it couldn't be 773If this call isn't available because your OS lacks it or it couldn't be
545detected, it will be emulated by calling C<fsync> instead. 774detected, it will be emulated by calling C<fsync> instead.
546 775
547=item aio_group $callback->(...) 776=item aio_group $callback->(...)
548 777
549[EXPERIMENTAL]
550
551This is a very special aio request: Instead of doing something, it is a 778This is a very special aio request: Instead of doing something, it is a
552container for other aio requests, which is useful if you want to bundle 779container for other aio requests, which is useful if you want to bundle
553many requests into a single, composite, request. 780many requests into a single, composite, request with a definite callback
781and the ability to cancel the whole request with its subrequests.
554 782
555Returns an object of class L<IO::AIO::GRP>. See its documentation below 783Returns an object of class L<IO::AIO::GRP>. See its documentation below
556for more info. 784for more info.
557 785
558Example: 786Example:
577phase and still requires a worker thread. Thus, the callback will not 805phase and still requires a worker thread. Thus, the callback will not
578be executed immediately but only after other requests in the queue have 806be executed immediately but only after other requests in the queue have
579entered their execution phase. This can be used to measure request 807entered their execution phase. This can be used to measure request
580latency. 808latency.
581 809
582=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED* 810=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
583 811
584Mainly used for debugging and benchmarking, this aio request puts one of 812Mainly used for debugging and benchmarking, this aio request puts one of
585the request workers to sleep for the given time. 813the request workers to sleep for the given time.
586 814
587While it is theoretically handy to have simple I/O scheduling requests 815While it is theoretically handy to have simple I/O scheduling requests
588like sleep and file handle readable/writable, the overhead this creates 816like sleep and file handle readable/writable, the overhead this creates is
589is immense, so do not use this function except to put your application 817immense (it blocks a thread for a long time) so do not use this function
590under artificial I/O pressure. 818except to put your application under artificial I/O pressure.
591 819
592=back 820=back
593 821
594=head2 IO::AIO::REQ CLASS 822=head2 IO::AIO::REQ CLASS
595 823
596All non-aggregate C<aio_*> functions return an object of this class when 824All non-aggregate C<aio_*> functions return an object of this class when
597called in non-void context. 825called in non-void context.
598
599A request always moves through the following five states in its lifetime,
600in order: B<ready> (request has been created, but has not been executed
601yet), B<execute> (request is currently being executed), B<pending>
602(request has been executed but callback has not been called yet),
603B<result> (results are being processed synchronously, includes calling the
604callback) and B<done> (request has reached the end of its lifetime and
605holds no resources anymore).
606 826
607=over 4 827=over 4
608 828
609=item cancel $req 829=item cancel $req
610 830
664=item * They can also can also be added to other IO::AIO::GRP objects. 884=item * They can also can also be added to other IO::AIO::GRP objects.
665 885
666=item * You must not add requests to a group from within the group callback (or 886=item * You must not add requests to a group from within the group callback (or
667any later time). 887any later time).
668 888
669=item * This does not harmonise well with C<max_outstanding>, so best do
670not combine C<aio_group> with it. Groups and feeders are recommended for
671this kind of concurrency-limiting.
672
673=back 889=back
674 890
675Their lifetime, simplified, looks like this: when they are empty, they 891Their lifetime, simplified, looks like this: when they are empty, they
676will finish very quickly. If they contain only requests that are in the 892will finish very quickly. If they contain only requests that are in the
677C<done> state, they will also finish. Otherwise they will continue to 893C<done> state, they will also finish. Otherwise they will continue to
692be added, including other groups, as long as you do not create circular 908be added, including other groups, as long as you do not create circular
693dependencies. 909dependencies.
694 910
695Returns all its arguments. 911Returns all its arguments.
696 912
913=item $grp->cancel_subs
914
915Cancel all subrequests and clears any feeder, but not the group request
916itself. Useful when you queued a lot of events but got a result early.
917
697=item $grp->result (...) 918=item $grp->result (...)
698 919
699Set the result value(s) that will be passed to the group callback when all 920Set the result value(s) that will be passed to the group callback when all
700subrequests have finished. By default, no argument will be passed. 921subrequests have finished and set thre groups errno to the current value
922of errno (just like calling C<errno> without an error number). By default,
923no argument will be passed and errno is zero.
924
925=item $grp->errno ([$errno])
926
927Sets the group errno value to C<$errno>, or the current value of errno
928when the argument is missing.
929
930Every aio request has an associated errno value that is restored when
931the callback is invoked. This method lets you change this value from its
932default (0).
933
934Calling C<result> will also set errno, so make sure you either set C<$!>
935before the call to C<result>, or call c<errno> after it.
701 936
702=item feed $grp $callback->($grp) 937=item feed $grp $callback->($grp)
703
704[VERY EXPERIMENTAL]
705 938
706Sets a feeder/generator on this group: every group can have an attached 939Sets a feeder/generator on this group: every group can have an attached
707generator that generates requests if idle. The idea behind this is that, 940generator that generates requests if idle. The idea behind this is that,
708although you could just queue as many requests as you want in a group, 941although you could just queue as many requests as you want in a group,
709this might starve other requests for a potentially long time. For 942this might starve other requests for a potentially long time. For
746 979
747=back 980=back
748 981
749=head2 SUPPORT FUNCTIONS 982=head2 SUPPORT FUNCTIONS
750 983
984=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
985
751=over 4 986=over 4
752 987
753=item $fileno = IO::AIO::poll_fileno 988=item $fileno = IO::AIO::poll_fileno
754 989
755Return the I<request result pipe file descriptor>. This filehandle must be 990Return the I<request result pipe file descriptor>. This filehandle must be
759 994
760See C<poll_cb> for an example. 995See C<poll_cb> for an example.
761 996
762=item IO::AIO::poll_cb 997=item IO::AIO::poll_cb
763 998
764Process all outstanding events on the result pipe. You have to call this 999Process some outstanding events on the result pipe. You have to call this
765regularly. Returns the number of events processed. Returns immediately 1000regularly. Returns the number of events processed. Returns immediately
766when no events are outstanding. 1001when no events are outstanding. The amount of events processed depends on
1002the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1003
1004If not all requests were processed for whatever reason, the filehandle
1005will still be ready when C<poll_cb> returns.
767 1006
768Example: Install an Event watcher that automatically calls 1007Example: Install an Event watcher that automatically calls
769IO::AIO::poll_cb with high priority: 1008IO::AIO::poll_cb with high priority:
770 1009
771 Event->io (fd => IO::AIO::poll_fileno, 1010 Event->io (fd => IO::AIO::poll_fileno,
772 poll => 'r', async => 1, 1011 poll => 'r', async => 1,
773 cb => \&IO::AIO::poll_cb); 1012 cb => \&IO::AIO::poll_cb);
774 1013
1014=item IO::AIO::max_poll_reqs $nreqs
1015
1016=item IO::AIO::max_poll_time $seconds
1017
1018These set the maximum number of requests (default C<0>, meaning infinity)
1019that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1020the maximum amount of time (default C<0>, meaning infinity) spent in
1021C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1022of time C<poll_cb> is allowed to use).
1023
1024Setting C<max_poll_time> to a non-zero value creates an overhead of one
1025syscall per request processed, which is not normally a problem unless your
1026callbacks are really really fast or your OS is really really slow (I am
1027not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1028
1029Setting these is useful if you want to ensure some level of
1030interactiveness when perl is not fast enough to process all requests in
1031time.
1032
1033For interactive programs, values such as C<0.01> to C<0.1> should be fine.
1034
1035Example: Install an Event watcher that automatically calls
1036IO::AIO::poll_cb with low priority, to ensure that other parts of the
1037program get the CPU sometimes even under high AIO load.
1038
1039 # try not to spend much more than 0.1s in poll_cb
1040 IO::AIO::max_poll_time 0.1;
1041
1042 # use a low priority so other tasks have priority
1043 Event->io (fd => IO::AIO::poll_fileno,
1044 poll => 'r', nice => 1,
1045 cb => &IO::AIO::poll_cb);
1046
775=item IO::AIO::poll_wait 1047=item IO::AIO::poll_wait
776 1048
1049If there are any outstanding requests and none of them in the result
777Wait till the result filehandle becomes ready for reading (simply does a 1050phase, wait till the result filehandle becomes ready for reading (simply
778C<select> on the filehandle. This is useful if you want to synchronously wait 1051does a C<select> on the filehandle. This is useful if you want to
779for some requests to finish). 1052synchronously wait for some requests to finish).
780 1053
781See C<nreqs> for an example. 1054See C<nreqs> for an example.
782 1055
1056=item IO::AIO::poll
1057
1058Waits until some requests have been handled.
1059
1060Returns the number of requests processed, but is otherwise strictly
1061equivalent to:
1062
1063 IO::AIO::poll_wait, IO::AIO::poll_cb
1064
783=item IO::AIO::nreqs 1065=item IO::AIO::flush
784 1066
785Returns the number of requests currently outstanding (i.e. for which their 1067Wait till all outstanding AIO requests have been handled.
786callback has not been invoked yet).
787 1068
788Example: wait till there are no outstanding requests anymore: 1069Strictly equivalent to:
789 1070
790 IO::AIO::poll_wait, IO::AIO::poll_cb 1071 IO::AIO::poll_wait, IO::AIO::poll_cb
791 while IO::AIO::nreqs; 1072 while IO::AIO::nreqs;
792 1073
793=item IO::AIO::flush 1074=head3 CONTROLLING THE NUMBER OF THREADS
794
795Wait till all outstanding AIO requests have been handled.
796
797Strictly equivalent to:
798
799 IO::AIO::poll_wait, IO::AIO::poll_cb
800 while IO::AIO::nreqs;
801
802=item IO::AIO::poll
803
804Waits until some requests have been handled.
805
806Strictly equivalent to:
807
808 IO::AIO::poll_wait, IO::AIO::poll_cb
809 if IO::AIO::nreqs;
810 1075
811=item IO::AIO::min_parallel $nthreads 1076=item IO::AIO::min_parallel $nthreads
812 1077
813Set the minimum number of AIO threads to C<$nthreads>. The current 1078Set the minimum number of AIO threads to C<$nthreads>. The current
814default is C<8>, which means eight asynchronous operations can execute 1079default is C<8>, which means eight asynchronous operations can execute
815concurrently at any one time (the number of outstanding requests, 1080concurrently at any one time (the number of outstanding requests,
816however, is unlimited). 1081however, is unlimited).
817 1082
818IO::AIO starts threads only on demand, when an AIO request is queued and 1083IO::AIO starts threads only on demand, when an AIO request is queued and
819no free thread exists. 1084no free thread exists. Please note that queueing up a hundred requests can
1085create demand for a hundred threads, even if it turns out that everything
1086is in the cache and could have been processed faster by a single thread.
820 1087
821It is recommended to keep the number of threads relatively low, as some 1088It is recommended to keep the number of threads relatively low, as some
822Linux kernel versions will scale negatively with the number of threads 1089Linux kernel versions will scale negatively with the number of threads
823(higher parallelity => MUCH higher latency). With current Linux 2.6 1090(higher parallelity => MUCH higher latency). With current Linux 2.6
824versions, 4-32 threads should be fine. 1091versions, 4-32 threads should be fine.
838This module automatically runs C<max_parallel 0> at program end, to ensure 1105This module automatically runs C<max_parallel 0> at program end, to ensure
839that all threads are killed and that there are no outstanding requests. 1106that all threads are killed and that there are no outstanding requests.
840 1107
841Under normal circumstances you don't need to call this function. 1108Under normal circumstances you don't need to call this function.
842 1109
1110=item IO::AIO::max_idle $nthreads
1111
1112Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1113threads that did not get a request to process within 10 seconds). That
1114means if a thread becomes idle while C<$nthreads> other threads are also
1115idle, it will free its resources and exit.
1116
1117This is useful when you allow a large number of threads (e.g. 100 or 1000)
1118to allow for extremely high load situations, but want to free resources
1119under normal circumstances (1000 threads can easily consume 30MB of RAM).
1120
1121The default is probably ok in most situations, especially if thread
1122creation is fast. If thread creation is very slow on your system you might
1123want to use larger values.
1124
843=item $oldnreqs = IO::AIO::max_outstanding $nreqs 1125=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
844 1126
845[DEPRECATED] 1127This is a very bad function to use in interactive programs because it
1128blocks, and a bad way to reduce concurrency because it is inexact: Better
1129use an C<aio_group> together with a feed callback.
846 1130
847Sets the maximum number of outstanding requests to C<$nreqs>. If you 1131Sets the maximum number of outstanding requests to C<$nreqs>. If you
848try to queue up more than this number of requests, the caller will block until 1132to queue up more than this number of requests, the next call to the
849some requests have been handled. 1133C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1134function will block until the limit is no longer exceeded.
850 1135
851The default is very large, so normally there is no practical limit. If you 1136The default value is very large, so there is no practical limit on the
852queue up many requests in a loop it often improves speed if you set 1137number of outstanding requests.
853this to a relatively low number, such as C<100>.
854 1138
855This function does not work well together with C<aio_group>'s, and their 1139You can still queue as many requests as you want. Therefore,
856feeder interface is better suited to limiting concurrency, so do not use 1140C<max_oustsanding> is mainly useful in simple scripts (with low values) or
857this function. 1141as a stop gap to shield against fatal memory overflow (with large values).
858 1142
859Under normal circumstances you don't need to call this function. 1143=head3 STATISTICAL INFORMATION
1144
1145=item IO::AIO::nreqs
1146
1147Returns the number of requests currently in the ready, execute or pending
1148states (i.e. for which their callback has not been invoked yet).
1149
1150Example: wait till there are no outstanding requests anymore:
1151
1152 IO::AIO::poll_wait, IO::AIO::poll_cb
1153 while IO::AIO::nreqs;
1154
1155=item IO::AIO::nready
1156
1157Returns the number of requests currently in the ready state (not yet
1158executed).
1159
1160=item IO::AIO::npending
1161
1162Returns the number of requests currently in the pending state (executed,
1163but not yet processed by poll_cb).
860 1164
861=back 1165=back
862 1166
863=cut 1167=cut
864 1168
878 *$sym 1182 *$sym
879} 1183}
880 1184
881min_parallel 8; 1185min_parallel 8;
882 1186
883END { 1187END { flush }
884 max_parallel 0;
885}
886 1188
8871; 11891;
888 1190
889=head2 FORK BEHAVIOUR 1191=head2 FORK BEHAVIOUR
890 1192
891This module should do "the right thing" when the process using it forks: 1193This module should do "the right thing" when the process using it forks:
892 1194
893Before the fork, IO::AIO enters a quiescent state where no requests 1195Before the fork, IO::AIO enters a quiescent state where no requests
894can be added in other threads and no results will be processed. After 1196can be added in other threads and no results will be processed. After
895the fork the parent simply leaves the quiescent state and continues 1197the fork the parent simply leaves the quiescent state and continues
896request/result processing, while the child clears the request/result 1198request/result processing, while the child frees the request/result queue
897queue (so the requests started before the fork will only be handled in 1199(so that the requests started before the fork will only be handled in the
898the parent). Threads will be started on demand until the limit ste in the 1200parent). Threads will be started on demand until the limit set in the
899parent process has been reached again. 1201parent process has been reached again.
900 1202
901In short: the parent will, after a short pause, continue as if fork had 1203In short: the parent will, after a short pause, continue as if fork had
902not been called, while the child will act as if IO::AIO has not been used 1204not been called, while the child will act as if IO::AIO has not been used
903yet. 1205yet.
904 1206
905=head2 MEMORY USAGE 1207=head2 MEMORY USAGE
906 1208
1209Per-request usage:
1210
907Each aio request uses - depending on your architecture - around 128 bytes 1211Each aio request uses - depending on your architecture - around 100-200
908of memory. In addition, stat requests need a stat buffer (possibly a few 1212bytes of memory. In addition, stat requests need a stat buffer (possibly
909hundred bytes). Perl scalars and other data passed into aio requests will 1213a few hundred bytes), readdir requires a result buffer and so on. Perl
910also be locked. 1214scalars and other data passed into aio requests will also be locked and
1215will consume memory till the request has entered the done state.
911 1216
912This is now awfully much, so queuing lots of requests is not usually a 1217This is now awfully much, so queuing lots of requests is not usually a
913problem. 1218problem.
914 1219
915Each thread needs a stack area which is usually around 16k, sometimes much 1220Per-thread usage:
916larger, depending on the OS. 1221
1222In the execution phase, some aio requests require more memory for
1223temporary buffers, and each thread requires a stack and other data
1224structures (usually around 16k-128k, depending on the OS).
1225
1226=head1 KNOWN BUGS
1227
1228Known bugs will be fixed in the next release.
917 1229
918=head1 SEE ALSO 1230=head1 SEE ALSO
919 1231
920L<Coro::AIO>. 1232L<Coro::AIO>.
921 1233

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