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Revision 1.32 by root, Wed Aug 17 05:26:20 2005 UTC vs.
Revision 1.52 by root, Sat Oct 21 23:06:04 2006 UTC

14 aio_unlink "/tmp/file", sub { }; 14 aio_unlink "/tmp/file", sub { };
15 15
16 aio_read $fh, 30000, 1024, $buffer, 0, sub { 16 aio_read $fh, 30000, 1024, $buffer, 0, sub {
17 $_[0] > 0 or die "read error: $!"; 17 $_[0] > 0 or die "read error: $!";
18 }; 18 };
19
20 use IO::AIO 2; # version has aio objects
21
22 my $req = aio_unlink "/tmp/file", sub { };
23 $req->cancel; # cancel request if still in queue
24
25 # AnyEvent
26 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
27 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
19 28
20 # Event 29 # Event
21 Event->io (fd => IO::AIO::poll_fileno, 30 Event->io (fd => IO::AIO::poll_fileno,
22 poll => 'r', 31 poll => 'r',
23 cb => \&IO::AIO::poll_cb); 32 cb => \&IO::AIO::poll_cb);
57=cut 66=cut
58 67
59package IO::AIO; 68package IO::AIO;
60 69
61no warnings; 70no warnings;
71use strict 'vars';
62 72
63use base 'Exporter'; 73use base 'Exporter';
64 74
65use Fcntl ();
66
67BEGIN { 75BEGIN {
68 $VERSION = 1.3; 76 our $VERSION = '1.8';
69 77
70
71 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink 78 our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
72 aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead); 79 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
80 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move);
73 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); 81 our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
74 82
75 require XSLoader; 83 require XSLoader;
76 XSLoader::load IO::AIO, $VERSION; 84 XSLoader::load ("IO::AIO", $VERSION);
77} 85}
78 86
79=head1 FUNCTIONS 87=head1 FUNCTIONS
80 88
81=head2 AIO FUNCTIONS 89=head2 AIO FUNCTIONS
89syscall has been executed asynchronously. 97syscall has been executed asynchronously.
90 98
91All functions expecting a filehandle keep a copy of the filehandle 99All functions expecting a filehandle keep a copy of the filehandle
92internally until the request has finished. 100internally until the request has finished.
93 101
102All non-composite requests (requests that are not broken down into
103multiple requests) return objects of type L<IO::AIO::REQ> that allow
104further manipulation of running requests.
105
94The pathnames you pass to these routines I<must> be absolute and 106The pathnames you pass to these routines I<must> be absolute and
95encoded in byte form. The reason for the former is that at the time the 107encoded in byte form. The reason for the former is that at the time the
96request is being executed, the current working directory could have 108request is being executed, the current working directory could have
97changed. Alternatively, you can make sure that you never change the 109changed. Alternatively, you can make sure that you never change the
98current working directory. 110current working directory.
104environment, d) use Glib::filename_from_unicode on unicode filenames or e) 116environment, d) use Glib::filename_from_unicode on unicode filenames or e)
105use something else. 117use something else.
106 118
107=over 4 119=over 4
108 120
109=item aio_open $pathname, $flags, $mode, $callback 121=item aio_open $pathname, $flags, $mode, $callback->($fh)
110 122
111Asynchronously open or create a file and call the callback with a newly 123Asynchronously open or create a file and call the callback with a newly
112created filehandle for the file. 124created filehandle for the file.
113 125
114The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 126The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
131 } else { 143 } else {
132 die "open failed: $!\n"; 144 die "open failed: $!\n";
133 } 145 }
134 }; 146 };
135 147
136=item aio_close $fh, $callback 148=item aio_close $fh, $callback->($status)
137 149
138Asynchronously close a file and call the callback with the result 150Asynchronously close a file and call the callback with the result
139code. I<WARNING:> although accepted, you should not pass in a perl 151code. I<WARNING:> although accepted, you should not pass in a perl
140filehandle here, as perl will likely close the file descriptor another 152filehandle here, as perl will likely close the file descriptor another
141time when the filehandle is destroyed. Normally, you can safely call perls 153time when the filehandle is destroyed. Normally, you can safely call perls
142C<close> or just let filehandles go out of scope. 154C<close> or just let filehandles go out of scope.
143 155
144This is supposed to be a bug in the API, so that might change. It's 156This is supposed to be a bug in the API, so that might change. It's
145therefore best to avoid this function. 157therefore best to avoid this function.
146 158
147=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 159=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
148 160
149=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 161=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
150 162
151Reads or writes C<length> bytes from the specified C<fh> and C<offset> 163Reads or writes C<length> bytes from the specified C<fh> and C<offset>
152into the scalar given by C<data> and offset C<dataoffset> and calls the 164into the scalar given by C<data> and offset C<dataoffset> and calls the
153callback without the actual number of bytes read (or -1 on error, just 165callback without the actual number of bytes read (or -1 on error, just
154like the syscall). 166like the syscall).
163 aio_read $fh, 7, 15, $buffer, 0, sub { 175 aio_read $fh, 7, 15, $buffer, 0, sub {
164 $_[0] > 0 or die "read error: $!"; 176 $_[0] > 0 or die "read error: $!";
165 print "read $_[0] bytes: <$buffer>\n"; 177 print "read $_[0] bytes: <$buffer>\n";
166 }; 178 };
167 179
180=item aio_move $srcpath, $dstpath, $callback->($status)
181
182Try to move the I<file> (directories not supported as either source or
183destination) from C<$srcpath> to C<$dstpath> and call the callback with
184the C<0> (error) or C<-1> ok.
185
186This is a composite request that tries to rename(2) the file first. If
187rename files with C<EXDEV>, it creates the destination file with mode 0200
188and copies the contents of the source file into it using C<aio_sendfile>,
189followed by restoring atime, mtime, access mode and uid/gid, in that
190order, and unlinking the C<$srcpath>.
191
192If an error occurs, the partial destination file will be unlinked, if
193possible, except when setting atime, mtime, access mode and uid/gid, where
194errors are being ignored.
195
196=cut
197
198sub aio_move($$$) {
199 my ($src, $dst, $cb) = @_;
200
201 aio_rename $src, $dst, sub {
202 if ($_[0] && $! == EXDEV) {
203 aio_open $src, O_RDONLY, 0, sub {
204 if (my $src_fh = $_[0]) {
205 my @stat = stat $src_fh;
206
207 aio_open $dst, O_WRONLY, 0200, sub {
208 if (my $dst_fh = $_[0]) {
209 aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
210 close $src_fh;
211
212 if ($_[0] == $stat[7]) {
213 utime $stat[8], $stat[9], $dst;
214 chmod $stat[2] & 07777, $dst_fh;
215 chown $stat[4], $stat[5], $dst_fh;
216 close $dst_fh;
217
218 aio_unlink $src, sub {
219 $cb->($_[0]);
220 };
221 } else {
222 my $errno = $!;
223 aio_unlink $dst, sub {
224 $! = $errno;
225 $cb->(-1);
226 };
227 }
228 };
229 } else {
230 $cb->(-1);
231 }
232 },
233
234 } else {
235 $cb->(-1);
236 }
237 };
238 } else {
239 $cb->($_[0]);
240 }
241 };
242}
243
244=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
245
246Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
247reading at byte offset C<$in_offset>, and starts writing at the current
248file offset of C<$out_fh>. Because of that, it is not safe to issue more
249than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
250other.
251
252This call tries to make use of a native C<sendfile> syscall to provide
253zero-copy operation. For this to work, C<$out_fh> should refer to a
254socket, and C<$in_fh> should refer to mmap'able file.
255
256If the native sendfile call fails or is not implemented, it will be
257emulated, so you can call C<aio_sendfile> on any type of filehandle
258regardless of the limitations of the operating system.
259
260Please note, however, that C<aio_sendfile> can read more bytes from
261C<$in_fh> than are written, and there is no way to find out how many
262bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
263provides the number of bytes written to C<$out_fh>. Only if the result
264value equals C<$length> one can assume that C<$length> bytes have been
265read.
266
168=item aio_readahead $fh,$offset,$length, $callback 267=item aio_readahead $fh,$offset,$length, $callback->($retval)
169 268
170C<aio_readahead> populates the page cache with data from a file so that 269C<aio_readahead> populates the page cache with data from a file so that
171subsequent reads from that file will not block on disk I/O. The C<$offset> 270subsequent reads from that file will not block on disk I/O. The C<$offset>
172argument specifies the starting point from which data is to be read and 271argument specifies the starting point from which data is to be read and
173C<$length> specifies the number of bytes to be read. I/O is performed in 272C<$length> specifies the number of bytes to be read. I/O is performed in
177file. The current file offset of the file is left unchanged. 276file. The current file offset of the file is left unchanged.
178 277
179If that syscall doesn't exist (likely if your OS isn't Linux) it will be 278If that syscall doesn't exist (likely if your OS isn't Linux) it will be
180emulated by simply reading the data, which would have a similar effect. 279emulated by simply reading the data, which would have a similar effect.
181 280
182=item aio_stat $fh_or_path, $callback 281=item aio_stat $fh_or_path, $callback->($status)
183 282
184=item aio_lstat $fh, $callback 283=item aio_lstat $fh, $callback->($status)
185 284
186Works like perl's C<stat> or C<lstat> in void context. The callback will 285Works like perl's C<stat> or C<lstat> in void context. The callback will
187be called after the stat and the results will be available using C<stat _> 286be called after the stat and the results will be available using C<stat _>
188or C<-s _> etc... 287or C<-s _> etc...
189 288
199 aio_stat "/etc/passwd", sub { 298 aio_stat "/etc/passwd", sub {
200 $_[0] and die "stat failed: $!"; 299 $_[0] and die "stat failed: $!";
201 print "size is ", -s _, "\n"; 300 print "size is ", -s _, "\n";
202 }; 301 };
203 302
204=item aio_unlink $pathname, $callback 303=item aio_unlink $pathname, $callback->($status)
205 304
206Asynchronously unlink (delete) a file and call the callback with the 305Asynchronously unlink (delete) a file and call the callback with the
207result code. 306result code.
208 307
308=item aio_link $srcpath, $dstpath, $callback->($status)
309
310Asynchronously create a new link to the existing object at C<$srcpath> at
311the path C<$dstpath> and call the callback with the result code.
312
313=item aio_symlink $srcpath, $dstpath, $callback->($status)
314
315Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
316the path C<$dstpath> and call the callback with the result code.
317
318=item aio_rename $srcpath, $dstpath, $callback->($status)
319
320Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
321rename(2) and call the callback with the result code.
322
209=item aio_rmdir $pathname, $callback 323=item aio_rmdir $pathname, $callback->($status)
210 324
211Asynchronously rmdir (delete) a directory and call the callback with the 325Asynchronously rmdir (delete) a directory and call the callback with the
212result code. 326result code.
213 327
328=item aio_readdir $pathname, $callback->($entries)
329
330Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
331directory (i.e. opendir + readdir + closedir). The entries will not be
332sorted, and will B<NOT> include the C<.> and C<..> entries.
333
334The callback a single argument which is either C<undef> or an array-ref
335with the filenames.
336
337=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
338
339Scans a directory (similar to C<aio_readdir>) but additionally tries to
340separate the entries of directory C<$path> into two sets of names, ones
341you can recurse into (directories or links to them), and ones you cannot
342recurse into (everything else).
343
344C<aio_scandir> is a composite request that consists of many sub
345requests. C<$maxreq> specifies the maximum number of outstanding aio
346requests that this function generates. If it is C<< <= 0 >>, then a
347suitable default will be chosen (currently 8).
348
349On error, the callback is called without arguments, otherwise it receives
350two array-refs with path-relative entry names.
351
352Example:
353
354 aio_scandir $dir, 0, sub {
355 my ($dirs, $nondirs) = @_;
356 print "real directories: @$dirs\n";
357 print "everything else: @$nondirs\n";
358 };
359
360Implementation notes.
361
362The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
363
364After reading the directory, the modification time, size etc. of the
365directory before and after the readdir is checked, and if they match (and
366isn't the current time), the link count will be used to decide how many
367entries are directories (if >= 2). Otherwise, no knowledge of the number
368of subdirectories will be assumed.
369
370Then entries will be sorted into likely directories (everything without
371a non-initial dot currently) and likely non-directories (everything
372else). Then every entry plus an appended C</.> will be C<stat>'ed,
373likely directories first. If that succeeds, it assumes that the entry
374is a directory or a symlink to directory (which will be checked
375seperately). This is often faster than stat'ing the entry itself because
376filesystems might detect the type of the entry without reading the inode
377data (e.g. ext2fs filetype feature).
378
379If the known number of directories (link count - 2) has been reached, the
380rest of the entries is assumed to be non-directories.
381
382This only works with certainty on POSIX (= UNIX) filesystems, which
383fortunately are the vast majority of filesystems around.
384
385It will also likely work on non-POSIX filesystems with reduced efficiency
386as those tend to return 0 or 1 as link counts, which disables the
387directory counting heuristic.
388
389=cut
390
391sub aio_scandir($$$) {
392 my ($path, $maxreq, $cb) = @_;
393
394 $maxreq = 8 if $maxreq <= 0;
395
396 # stat once
397 aio_stat $path, sub {
398 return $cb->() if $_[0];
399 my $now = time;
400 my $hash1 = join ":", (stat _)[0,1,3,7,9];
401
402 # read the directory entries
403 aio_readdir $path, sub {
404 my $entries = shift
405 or return $cb->();
406
407 # stat the dir another time
408 aio_stat $path, sub {
409 my $hash2 = join ":", (stat _)[0,1,3,7,9];
410
411 my $ndirs;
412
413 # take the slow route if anything looks fishy
414 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
415 $ndirs = -1;
416 } else {
417 # if nlink == 2, we are finished
418 # on non-posix-fs's, we rely on nlink < 2
419 $ndirs = (stat _)[3] - 2
420 or return $cb->([], $entries);
421 }
422
423 # sort into likely dirs and likely nondirs
424 # dirs == files without ".", short entries first
425 $entries = [map $_->[0],
426 sort { $b->[1] cmp $a->[1] }
427 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
428 @$entries];
429
430 my (@dirs, @nondirs);
431
432 my ($statcb, $schedcb);
433 my $nreq = 0;
434
435 $schedcb = sub {
436 if (@$entries) {
437 if ($nreq < $maxreq) {
438 my $ent = pop @$entries;
439 $nreq++;
440 aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
441 }
442 } elsif (!$nreq) {
443 # finished
444 undef $statcb;
445 undef $schedcb;
446 $cb->(\@dirs, \@nondirs) if $cb;
447 undef $cb;
448 }
449 };
450 $statcb = sub {
451 my ($status, $entry) = @_;
452
453 if ($status < 0) {
454 $nreq--;
455 push @nondirs, $entry;
456 &$schedcb;
457 } else {
458 # need to check for real directory
459 aio_lstat "$path/$entry", sub {
460 $nreq--;
461
462 if (-d _) {
463 push @dirs, $entry;
464
465 if (!--$ndirs) {
466 push @nondirs, @$entries;
467 $entries = [];
468 }
469 } else {
470 push @nondirs, $entry;
471 }
472
473 &$schedcb;
474 }
475 }
476 };
477
478 &$schedcb while @$entries && $nreq < $maxreq;
479 };
480 };
481 };
482}
483
214=item aio_fsync $fh, $callback 484=item aio_fsync $fh, $callback->($status)
215 485
216Asynchronously call fsync on the given filehandle and call the callback 486Asynchronously call fsync on the given filehandle and call the callback
217with the fsync result code. 487with the fsync result code.
218 488
219=item aio_fdatasync $fh, $callback 489=item aio_fdatasync $fh, $callback->($status)
220 490
221Asynchronously call fdatasync on the given filehandle and call the 491Asynchronously call fdatasync on the given filehandle and call the
222callback with the fdatasync result code. 492callback with the fdatasync result code.
223 493
224If this call isn't available because your OS lacks it or it couldn't be 494If this call isn't available because your OS lacks it or it couldn't be
225detected, it will be emulated by calling C<fsync> instead. 495detected, it will be emulated by calling C<fsync> instead.
496
497=back
498
499=head2 IO::AIO::CB CLASS
500
501All non-aggregate C<aio_*> functions return an object of this class when
502called in non-void context.
503
504A request always moves through the following five states in its lifetime,
505in order: B<ready> (request has been created, but has not been executed
506yet), B<execute> (request is currently being executed), B<pending>
507(request has been executed but callback has not been called yet),
508B<result> (results are being processed synchronously, includes calling the
509callback) and B<done> (request has reached the end of its lifetime and
510holds no resources anymore).
511
512=over 4
513
514=item $req->cancel
515
516Cancels the request, if possible. Has the effect of skipping execution
517when entering the B<execute> state and skipping calling the callback when
518entering the the B<result> state, but will leave the request otherwise
519untouched. That means that requests that currently execute will not be
520stopped and resources held by the request will not be freed prematurely.
226 521
227=back 522=back
228 523
229=head2 SUPPORT FUNCTIONS 524=head2 SUPPORT FUNCTIONS
230 525
288 IO::AIO::poll_wait, IO::AIO::poll_cb 583 IO::AIO::poll_wait, IO::AIO::poll_cb
289 if IO::AIO::nreqs; 584 if IO::AIO::nreqs;
290 585
291=item IO::AIO::min_parallel $nthreads 586=item IO::AIO::min_parallel $nthreads
292 587
293Set the minimum number of AIO threads to C<$nthreads>. The default is 588Set the minimum number of AIO threads to C<$nthreads>. The current default
294C<1>, which means a single asynchronous operation can be done at one time 589is C<4>, which means four asynchronous operations can be done at one time
295(the number of outstanding operations, however, is unlimited). 590(the number of outstanding operations, however, is unlimited).
591
592IO::AIO starts threads only on demand, when an AIO request is queued and
593no free thread exists.
296 594
297It is recommended to keep the number of threads low, as some Linux 595It is recommended to keep the number of threads low, as some Linux
298kernel versions will scale negatively with the number of threads (higher 596kernel versions will scale negatively with the number of threads (higher
299parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 597parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
300threads should be fine. 598threads should be fine.
301 599
302Under normal circumstances you don't need to call this function, as this 600Under most circumstances you don't need to call this function, as the
303module automatically starts some threads (the exact number might change, 601module selects a default that is suitable for low to moderate load.
304and is currently 4).
305 602
306=item IO::AIO::max_parallel $nthreads 603=item IO::AIO::max_parallel $nthreads
307 604
308Sets the maximum number of AIO threads to C<$nthreads>. If more than 605Sets the maximum number of AIO threads to C<$nthreads>. If more than the
309the specified number of threads are currently running, kill them. This 606specified number of threads are currently running, this function kills
310function blocks until the limit is reached. 607them. This function blocks until the limit is reached.
608
609While C<$nthreads> are zero, aio requests get queued but not executed
610until the number of threads has been increased again.
311 611
312This module automatically runs C<max_parallel 0> at program end, to ensure 612This module automatically runs C<max_parallel 0> at program end, to ensure
313that all threads are killed and that there are no outstanding requests. 613that all threads are killed and that there are no outstanding requests.
314 614
315Under normal circumstances you don't need to call this function. 615Under normal circumstances you don't need to call this function.
319Sets the maximum number of outstanding requests to C<$nreqs>. If you 619Sets the maximum number of outstanding requests to C<$nreqs>. If you
320try to queue up more than this number of requests, the caller will block until 620try to queue up more than this number of requests, the caller will block until
321some requests have been handled. 621some requests have been handled.
322 622
323The default is very large, so normally there is no practical limit. If you 623The default is very large, so normally there is no practical limit. If you
324queue up many requests in a loop it it often improves speed if you set 624queue up many requests in a loop it often improves speed if you set
325this to a relatively low number, such as C<100>. 625this to a relatively low number, such as C<100>.
326 626
327Under normal circumstances you don't need to call this function. 627Under normal circumstances you don't need to call this function.
328 628
329=back 629=back
354 654
3551; 6551;
356 656
357=head2 FORK BEHAVIOUR 657=head2 FORK BEHAVIOUR
358 658
659This module should do "the right thing" when the process using it forks:
660
359Before the fork IO::AIO enters a quiescent state where no requests can be 661Before the fork, IO::AIO enters a quiescent state where no requests
360added in other threads and no results will be processed. After the fork 662can be added in other threads and no results will be processed. After
361the parent simply leaves the quiescent state and continues request/result 663the fork the parent simply leaves the quiescent state and continues
362processing, while the child clears the request/result queue and starts the 664request/result processing, while the child clears the request/result
363same number of threads as were in use by the parent. 665queue (so the requests started before the fork will only be handled in
666the parent). Threads will be started on demand until the limit ste in the
667parent process has been reached again.
668
669In short: the parent will, after a short pause, continue as if fork had
670not been called, while the child will act as if IO::AIO has not been used
671yet.
364 672
365=head1 SEE ALSO 673=head1 SEE ALSO
366 674
367L<Coro>, L<Linux::AIO>. 675L<Coro>, L<Linux::AIO> (obsolete).
368 676
369=head1 AUTHOR 677=head1 AUTHOR
370 678
371 Marc Lehmann <schmorp@schmorp.de> 679 Marc Lehmann <schmorp@schmorp.de>
372 http://home.schmorp.de/ 680 http://home.schmorp.de/

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