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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.50 by root, Sat Jun 24 16:27:02 2006 UTC vs.
Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC

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 19
20 # AnyEvent 20 # version 2+ has request and group objects
21 use IO::AIO 2;
22
23 aioreq_pri 4; # give next request a very high priority
24 my $req = aio_unlink "/tmp/file", sub { };
25 $req->cancel; # cancel request if still in queue
26
27 my $grp = aio_group sub { print "all stats done\n" };
28 add $grp aio_stat "..." for ...;
29
30 # AnyEvent integration
21 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; 31 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
22 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); 32 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
23 33
24 # Event 34 # Event integration
25 Event->io (fd => IO::AIO::poll_fileno, 35 Event->io (fd => IO::AIO::poll_fileno,
26 poll => 'r', 36 poll => 'r',
27 cb => \&IO::AIO::poll_cb); 37 cb => \&IO::AIO::poll_cb);
28 38
29 # Glib/Gtk2 39 # Glib/Gtk2 integration
30 add_watch Glib::IO IO::AIO::poll_fileno, 40 add_watch Glib::IO IO::AIO::poll_fileno,
31 in => sub { IO::AIO::poll_cb; 1 }; 41 in => sub { IO::AIO::poll_cb; 1 };
32 42
33 # Tk 43 # Tk integration
34 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", 44 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
35 readable => \&IO::AIO::poll_cb); 45 readable => \&IO::AIO::poll_cb);
36 46
37 # Danga::Socket 47 # Danga::Socket integration
38 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 48 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
39 \&IO::AIO::poll_cb); 49 \&IO::AIO::poll_cb);
40 50
41
42=head1 DESCRIPTION 51=head1 DESCRIPTION
43 52
44This module implements asynchronous I/O using whatever means your 53This module implements asynchronous I/O using whatever means your
45operating system supports. 54operating system supports.
46 55
56Asynchronous means that operations that can normally block your program
57(e.g. reading from disk) will be done asynchronously: the operation
58will still block, but you can do something else in the meantime. This
59is extremely useful for programs that need to stay interactive even
60when doing heavy I/O (GUI programs, high performance network servers
61etc.), but can also be used to easily do operations in parallel that are
62normally done sequentially, e.g. stat'ing many files, which is much faster
63on a RAID volume or over NFS when you do a number of stat operations
64concurrently.
65
66While this works on all types of file descriptors (for example sockets),
67using these functions on file descriptors that support nonblocking
68operation (again, sockets, pipes etc.) is very inefficient. Use an event
69loop for that (such as the L<Event|Event> module): IO::AIO will naturally
70fit into such an event loop itself.
71
47Currently, a number of threads are started that execute your read/writes 72In this version, a number of threads are started that execute your
48and signal their completion. You don't need thread support in your libc or 73requests and signal their completion. You don't need thread support
49perl, and the threads created by this module will not be visible to the 74in perl, and the threads created by this module will not be visible
50pthreads library. In the future, this module might make use of the native 75to perl. In the future, this module might make use of the native aio
51aio functions available on many operating systems. However, they are often 76functions available on many operating systems. However, they are often
52not well-supported (Linux doesn't allow them on normal files currently, 77not well-supported or restricted (GNU/Linux doesn't allow them on normal
53for example), and they would only support aio_read and aio_write, so the 78files currently, for example), and they would only support aio_read and
54remaining functionality would have to be implemented using threads anyway. 79aio_write, so the remaining functionality would have to be implemented
80using threads anyway.
55 81
56Although the module will work with in the presence of other threads, it is 82Although the module will work with in the presence of other (Perl-)
57currently not reentrant, so use appropriate locking yourself, always call 83threads, it is currently not reentrant in any way, so use appropriate
58C<poll_cb> from within the same thread, or never call C<poll_cb> (or other 84locking yourself, always call C<poll_cb> from within the same thread, or
59C<aio_> functions) recursively. 85never call C<poll_cb> (or other C<aio_> functions) recursively.
86
87=head2 EXAMPLE
88
89This is a simple example that uses the Event module and loads
90F</etc/passwd> asynchronously:
91
92 use Fcntl;
93 use Event;
94 use IO::AIO;
95
96 # register the IO::AIO callback with Event
97 Event->io (fd => IO::AIO::poll_fileno,
98 poll => 'r',
99 cb => \&IO::AIO::poll_cb);
100
101 # queue the request to open /etc/passwd
102 aio_open "/etc/passwd", O_RDONLY, 0, sub {
103 my $fh = $_[0]
104 or die "error while opening: $!";
105
106 # stat'ing filehandles is generally non-blocking
107 my $size = -s $fh;
108
109 # queue a request to read the file
110 my $contents;
111 aio_read $fh, 0, $size, $contents, 0, sub {
112 $_[0] == $size
113 or die "short read: $!";
114
115 close $fh;
116
117 # file contents now in $contents
118 print $contents;
119
120 # exit event loop and program
121 Event::unloop;
122 };
123 };
124
125 # possibly queue up other requests, or open GUI windows,
126 # check for sockets etc. etc.
127
128 # process events as long as there are some:
129 Event::loop;
130
131=head1 REQUEST ANATOMY AND LIFETIME
132
133Every C<aio_*> function creates a request. which is a C data structure not
134directly visible to Perl.
135
136If called in non-void context, every request function returns a Perl
137object representing the request. In void context, nothing is returned,
138which saves a bit of memory.
139
140The perl object is a fairly standard ref-to-hash object. The hash contents
141are not used by IO::AIO so you are free to store anything you like in it.
142
143During their existance, aio requests travel through the following states,
144in order:
145
146=over 4
147
148=item ready
149
150Immediately after a request is created it is put into the ready state,
151waiting for a thread to execute it.
152
153=item execute
154
155A thread has accepted the request for processing and is currently
156executing it (e.g. blocking in read).
157
158=item pending
159
160The request has been executed and is waiting for result processing.
161
162While request submission and execution is fully asynchronous, result
163processing is not and relies on the perl interpreter calling C<poll_cb>
164(or another function with the same effect).
165
166=item result
167
168The request results are processed synchronously by C<poll_cb>.
169
170The C<poll_cb> function will process all outstanding aio requests by
171calling their callbacks, freeing memory associated with them and managing
172any groups they are contained in.
173
174=item done
175
176Request has reached the end of its lifetime and holds no resources anymore
177(except possibly for the Perl object, but its connection to the actual
178aio request is severed and calling its methods will either do nothing or
179result in a runtime error).
180
181=back
60 182
61=cut 183=cut
62 184
63package IO::AIO; 185package IO::AIO;
64 186
65no warnings; 187no warnings;
188use strict 'vars';
66 189
67use base 'Exporter'; 190use base 'Exporter';
68 191
69use Fcntl ();
70
71BEGIN { 192BEGIN {
72 $VERSION = '1.8'; 193 our $VERSION = '2.1';
73 194
74 @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 195 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
75 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 196 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
76 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move); 197 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
77 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel 198 aio_copy aio_group aio_nop aio_mknod);
78 max_outstanding nreqs); 199 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
200 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
201 min_parallel max_parallel max_idle
202 nreqs nready npending nthreads
203 max_poll_time max_poll_reqs);
204
205 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
79 206
80 require XSLoader; 207 require XSLoader;
81 XSLoader::load IO::AIO, $VERSION; 208 XSLoader::load ("IO::AIO", $VERSION);
82} 209}
83 210
84=head1 FUNCTIONS 211=head1 FUNCTIONS
85 212
86=head2 AIO FUNCTIONS 213=head2 AIO REQUEST FUNCTIONS
87 214
88All the C<aio_*> calls are more or less thin wrappers around the syscall 215All the C<aio_*> calls are more or less thin wrappers around the syscall
89with the same name (sans C<aio_>). The arguments are similar or identical, 216with the same name (sans C<aio_>). The arguments are similar or identical,
90and they all accept an additional (and optional) C<$callback> argument 217and they all accept an additional (and optional) C<$callback> argument
91which must be a code reference. This code reference will get called with 218which must be a code reference. This code reference will get called with
94syscall has been executed asynchronously. 221syscall has been executed asynchronously.
95 222
96All functions expecting a filehandle keep a copy of the filehandle 223All functions expecting a filehandle keep a copy of the filehandle
97internally until the request has finished. 224internally until the request has finished.
98 225
226All functions return request objects of type L<IO::AIO::REQ> that allow
227further manipulation of those requests while they are in-flight.
228
99The pathnames you pass to these routines I<must> be absolute and 229The pathnames you pass to these routines I<must> be absolute and
100encoded in byte form. The reason for the former is that at the time the 230encoded as octets. The reason for the former is that at the time the
101request is being executed, the current working directory could have 231request is being executed, the current working directory could have
102changed. Alternatively, you can make sure that you never change the 232changed. Alternatively, you can make sure that you never change the
103current working directory. 233current working directory anywhere in the program and then use relative
234paths.
104 235
105To encode pathnames to byte form, either make sure you either: a) 236To encode pathnames as octets, either make sure you either: a) always pass
106always pass in filenames you got from outside (command line, readdir 237in filenames you got from outside (command line, readdir etc.) without
107etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode 238tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
108your pathnames to the locale (or other) encoding in effect in the user 239your pathnames to the locale (or other) encoding in effect in the user
109environment, d) use Glib::filename_from_unicode on unicode filenames or e) 240environment, d) use Glib::filename_from_unicode on unicode filenames or e)
110use something else. 241use something else to ensure your scalar has the correct contents.
242
243This works, btw. independent of the internal UTF-8 bit, which IO::AIO
244handles correctly wether it is set or not.
111 245
112=over 4 246=over 4
247
248=item $prev_pri = aioreq_pri [$pri]
249
250Returns the priority value that would be used for the next request and, if
251C<$pri> is given, sets the priority for the next aio request.
252
253The default priority is C<0>, the minimum and maximum priorities are C<-4>
254and C<4>, respectively. Requests with higher priority will be serviced
255first.
256
257The priority will be reset to C<0> after each call to one of the C<aio_*>
258functions.
259
260Example: open a file with low priority, then read something from it with
261higher priority so the read request is serviced before other low priority
262open requests (potentially spamming the cache):
263
264 aioreq_pri -3;
265 aio_open ..., sub {
266 return unless $_[0];
267
268 aioreq_pri -2;
269 aio_read $_[0], ..., sub {
270 ...
271 };
272 };
273
274=item aioreq_nice $pri_adjust
275
276Similar to C<aioreq_pri>, but subtracts the given value from the current
277priority, so the effect is cumulative.
113 278
114=item aio_open $pathname, $flags, $mode, $callback->($fh) 279=item aio_open $pathname, $flags, $mode, $callback->($fh)
115 280
116Asynchronously open or create a file and call the callback with a newly 281Asynchronously open or create a file and call the callback with a newly
117created filehandle for the file. 282created filehandle for the file.
167 332
168 aio_read $fh, 7, 15, $buffer, 0, sub { 333 aio_read $fh, 7, 15, $buffer, 0, sub {
169 $_[0] > 0 or die "read error: $!"; 334 $_[0] > 0 or die "read error: $!";
170 print "read $_[0] bytes: <$buffer>\n"; 335 print "read $_[0] bytes: <$buffer>\n";
171 }; 336 };
172
173=item aio_move $srcpath, $dstpath, $callback->($status)
174
175[EXPERIMENTAL]
176
177Try to move the I<file> (directories not supported as either source or destination)
178from C<$srcpath> to C<$dstpath> and call the callback with the C<0> (error) or C<-1> ok.
179
180This is a composite request that tries to rename(2) the file first. If
181rename files with C<EXDEV>, it creates the destination file with mode 0200
182and copies the contents of the source file into it using C<aio_sendfile>,
183followed by restoring atime, mtime, access mode and uid/gid, in that
184order, and unlinking the C<$srcpath>.
185
186If an error occurs, the partial destination file will be unlinked, if
187possible, except when setting atime, mtime, access mode and uid/gid, where
188errors are being ignored.
189
190=cut
191
192sub aio_move($$$) {
193 my ($src, $dst, $cb) = @_;
194
195 aio_rename $src, $dst, sub {
196 if ($_[0] && $! == Errno::EXDEV) {
197 aio_open $src, O_RDONLY, 0, sub {
198 if (my $src_fh = $_[0]) {
199 my @stat = stat $src_fh;
200
201 aio_open $dst, O_WRONLY, 0200, sub {
202 if (my $dst_fh = $_[0]) {
203 aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
204 close $src_fh;
205
206 if ($_[0] == $stat[7]) {
207 utime $stat[8], $stat[9], $dst;
208 chmod $stat[2] & 07777, $dst_fh;
209 chown $stat[4], $stat[5], $dst_fh;
210 close $dst_fh;
211
212 aio_unlink $src, sub {
213 $cb->($_[0]);
214 };
215 } else {
216 my $errno = $!;
217 aio_unlink $dst, sub {
218 $! = $errno;
219 $cb->(-1);
220 };
221 }
222 };
223 } else {
224 $cb->(-1);
225 }
226 },
227
228 } else {
229 $cb->(-1);
230 }
231 };
232 } else {
233 $cb->($_[0]);
234 }
235 };
236}
237 337
238=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 338=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
239 339
240Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 340Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
241reading at byte offset C<$in_offset>, and starts writing at the current 341reading at byte offset C<$in_offset>, and starts writing at the current
297=item aio_unlink $pathname, $callback->($status) 397=item aio_unlink $pathname, $callback->($status)
298 398
299Asynchronously unlink (delete) a file and call the callback with the 399Asynchronously unlink (delete) a file and call the callback with the
300result code. 400result code.
301 401
402=item aio_mknod $path, $mode, $dev, $callback->($status)
403
404[EXPERIMENTAL]
405
406Asynchronously create a device node (or fifo). See mknod(2).
407
408The only (POSIX-) portable way of calling this function is:
409
410 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
411
302=item aio_link $srcpath, $dstpath, $callback->($status) 412=item aio_link $srcpath, $dstpath, $callback->($status)
303 413
304Asynchronously create a new link to the existing object at C<$srcpath> at 414Asynchronously create a new link to the existing object at C<$srcpath> at
305the path C<$dstpath> and call the callback with the result code. 415the path C<$dstpath> and call the callback with the result code.
306 416
326sorted, and will B<NOT> include the C<.> and C<..> entries. 436sorted, and will B<NOT> include the C<.> and C<..> entries.
327 437
328The callback a single argument which is either C<undef> or an array-ref 438The callback a single argument which is either C<undef> or an array-ref
329with the filenames. 439with the filenames.
330 440
441=item aio_copy $srcpath, $dstpath, $callback->($status)
442
443Try to copy the I<file> (directories not supported as either source or
444destination) from C<$srcpath> to C<$dstpath> and call the callback with
445the C<0> (error) or C<-1> ok.
446
447This is a composite request that it creates the destination file with
448mode 0200 and copies the contents of the source file into it using
449C<aio_sendfile>, followed by restoring atime, mtime, access mode and
450uid/gid, in that order.
451
452If an error occurs, the partial destination file will be unlinked, if
453possible, except when setting atime, mtime, access mode and uid/gid, where
454errors are being ignored.
455
456=cut
457
458sub aio_copy($$;$) {
459 my ($src, $dst, $cb) = @_;
460
461 my $pri = aioreq_pri;
462 my $grp = aio_group $cb;
463
464 aioreq_pri $pri;
465 add $grp aio_open $src, O_RDONLY, 0, sub {
466 if (my $src_fh = $_[0]) {
467 my @stat = stat $src_fh;
468
469 aioreq_pri $pri;
470 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
471 if (my $dst_fh = $_[0]) {
472 aioreq_pri $pri;
473 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
474 if ($_[0] == $stat[7]) {
475 $grp->result (0);
476 close $src_fh;
477
478 # those should not normally block. should. should.
479 utime $stat[8], $stat[9], $dst;
480 chmod $stat[2] & 07777, $dst_fh;
481 chown $stat[4], $stat[5], $dst_fh;
482 close $dst_fh;
483 } else {
484 $grp->result (-1);
485 close $src_fh;
486 close $dst_fh;
487
488 aioreq $pri;
489 add $grp aio_unlink $dst;
490 }
491 };
492 } else {
493 $grp->result (-1);
494 }
495 },
496
497 } else {
498 $grp->result (-1);
499 }
500 };
501
502 $grp
503}
504
505=item aio_move $srcpath, $dstpath, $callback->($status)
506
507Try to move the I<file> (directories not supported as either source or
508destination) from C<$srcpath> to C<$dstpath> and call the callback with
509the C<0> (error) or C<-1> ok.
510
511This is a composite request that tries to rename(2) the file first. If
512rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
513that is successful, unlinking the C<$srcpath>.
514
515=cut
516
517sub aio_move($$;$) {
518 my ($src, $dst, $cb) = @_;
519
520 my $pri = aioreq_pri;
521 my $grp = aio_group $cb;
522
523 aioreq_pri $pri;
524 add $grp aio_rename $src, $dst, sub {
525 if ($_[0] && $! == EXDEV) {
526 aioreq_pri $pri;
527 add $grp aio_copy $src, $dst, sub {
528 $grp->result ($_[0]);
529
530 if (!$_[0]) {
531 aioreq_pri $pri;
532 add $grp aio_unlink $src;
533 }
534 };
535 } else {
536 $grp->result ($_[0]);
537 }
538 };
539
540 $grp
541}
542
331=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 543=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
332 544
333Scans a directory (similar to C<aio_readdir>) and tries to separate the 545Scans a directory (similar to C<aio_readdir>) but additionally tries to
334entries of directory C<$path> into two sets of names, ones you can recurse 546efficiently separate the entries of directory C<$path> into two sets of
335into (directories), and ones you cannot recurse into (everything else). 547names, directories you can recurse into (directories), and ones you cannot
548recurse into (everything else, including symlinks to directories).
336 549
337C<aio_scandir> is a composite request that consists of many 550C<aio_scandir> is a composite request that creates of many sub requests_
338aio-primitives. C<$maxreq> specifies the maximum number of outstanding 551C<$maxreq> specifies the maximum number of outstanding aio requests that
339aio requests that this function generates. If it is C<< <= 0 >>, then a 552this function generates. If it is C<< <= 0 >>, then a suitable default
340suitable default will be chosen (currently 8). 553will be chosen (currently 4).
341 554
342On error, the callback is called without arguments, otherwise it receives 555On error, the callback is called without arguments, otherwise it receives
343two array-refs with path-relative entry names. 556two array-refs with path-relative entry names.
344 557
345Example: 558Example:
353Implementation notes. 566Implementation notes.
354 567
355The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. 568The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
356 569
357After reading the directory, the modification time, size etc. of the 570After reading the directory, the modification time, size etc. of the
358directory before and after the readdir is checked, and if they match, the 571directory before and after the readdir is checked, and if they match (and
359link count will be used to decide how many entries are directories (if 572isn't the current time), the link count will be used to decide how many
360>= 2). Otherwise, no knowledge of the number of subdirectories will be 573entries are directories (if >= 2). Otherwise, no knowledge of the number
361assumed. 574of subdirectories will be assumed.
362 575
363Then entires will be sorted into likely directories (everything without a 576Then entries will be sorted into likely directories (everything without
364non-initial dot) and likely non-directories (everything else). Then every 577a non-initial dot currently) and likely non-directories (everything
365entry + C</.> will be C<stat>'ed, likely directories first. This is often 578else). Then every entry plus an appended C</.> will be C<stat>'ed,
579likely directories first. If that succeeds, it assumes that the entry
580is a directory or a symlink to directory (which will be checked
581seperately). This is often faster than stat'ing the entry itself because
366faster because filesystems might detect the type of the entry without 582filesystems might detect the type of the entry without reading the inode
367reading the inode data (e.g. ext2fs filetype feature). If that succeeds, 583data (e.g. ext2fs filetype feature).
368it assumes that the entry is a directory or a symlink to directory (which
369will be checked seperately).
370 584
371If the known number of directories has been reached, the rest of the 585If the known number of directories (link count - 2) has been reached, the
372entries is assumed to be non-directories. 586rest of the entries is assumed to be non-directories.
587
588This only works with certainty on POSIX (= UNIX) filesystems, which
589fortunately are the vast majority of filesystems around.
590
591It will also likely work on non-POSIX filesystems with reduced efficiency
592as those tend to return 0 or 1 as link counts, which disables the
593directory counting heuristic.
373 594
374=cut 595=cut
375 596
376sub aio_scandir($$$) { 597sub aio_scandir($$$) {
377 my ($path, $maxreq, $cb) = @_; 598 my ($path, $maxreq, $cb) = @_;
378 599
600 my $pri = aioreq_pri;
601
602 my $grp = aio_group $cb;
603
379 $maxreq = 8 if $maxreq <= 0; 604 $maxreq = 4 if $maxreq <= 0;
380 605
381 # stat once 606 # stat once
607 aioreq_pri $pri;
382 aio_stat $path, sub { 608 add $grp aio_stat $path, sub {
383 return $cb->() if $_[0]; 609 return $grp->result () if $_[0];
610 my $now = time;
384 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 611 my $hash1 = join ":", (stat _)[0,1,3,7,9];
385 612
386 # read the directory entries 613 # read the directory entries
614 aioreq_pri $pri;
387 aio_readdir $path, sub { 615 add $grp aio_readdir $path, sub {
388 my $entries = shift 616 my $entries = shift
389 or return $cb->(); 617 or return $grp->result ();
390 618
391 # stat the dir another time 619 # stat the dir another time
620 aioreq_pri $pri;
392 aio_stat $path, sub { 621 add $grp aio_stat $path, sub {
393 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 622 my $hash2 = join ":", (stat _)[0,1,3,7,9];
394 623
395 my $ndirs; 624 my $ndirs;
396 625
397 # take the slow route if anything looks fishy 626 # take the slow route if anything looks fishy
398 if ($hash1 ne $hash2) { 627 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
399 $ndirs = -1; 628 $ndirs = -1;
400 } else { 629 } else {
401 # if nlink == 2, we are finished 630 # if nlink == 2, we are finished
402 # on non-posix-fs's, we rely on nlink < 2 631 # on non-posix-fs's, we rely on nlink < 2
403 $ndirs = (stat _)[3] - 2 632 $ndirs = (stat _)[3] - 2
404 or return $cb->([], $entries); 633 or return $grp->result ([], $entries);
405 } 634 }
406 635
407 # sort into likely dirs and likely nondirs 636 # sort into likely dirs and likely nondirs
408 # dirs == files without ".", short entries first 637 # dirs == files without ".", short entries first
409 $entries = [map $_->[0], 638 $entries = [map $_->[0],
411 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 640 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
412 @$entries]; 641 @$entries];
413 642
414 my (@dirs, @nondirs); 643 my (@dirs, @nondirs);
415 644
416 my ($statcb, $schedcb); 645 my $statgrp = add $grp aio_group sub {
417 my $nreq = 0; 646 $grp->result (\@dirs, \@nondirs);
647 };
418 648
419 $schedcb = sub { 649 limit $statgrp $maxreq;
420 if (@$entries) { 650 feed $statgrp sub {
421 if ($nreq < $maxreq) { 651 return unless @$entries;
422 my $ent = pop @$entries; 652 my $entry = pop @$entries;
653
654 aioreq_pri $pri;
655 add $statgrp aio_stat "$path/$entry/.", sub {
656 if ($_[0] < 0) {
657 push @nondirs, $entry;
658 } else {
659 # need to check for real directory
660 aioreq_pri $pri;
661 add $statgrp aio_lstat "$path/$entry", sub {
662 if (-d _) {
663 push @dirs, $entry;
664
665 unless (--$ndirs) {
666 push @nondirs, @$entries;
667 feed $statgrp;
668 }
669 } else {
670 push @nondirs, $entry;
671 }
423 $nreq++; 672 }
424 aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
425 } 673 }
426 } elsif (!$nreq) {
427 # finished
428 undef $statcb;
429 undef $schedcb;
430 $cb->(\@dirs, \@nondirs) if $cb;
431 undef $cb;
432 } 674 };
433 }; 675 };
434 $statcb = sub {
435 my ($status, $entry) = @_;
436
437 if ($status < 0) {
438 $nreq--;
439 push @nondirs, $entry;
440 &$schedcb;
441 } else {
442 # need to check for real directory
443 aio_lstat "$path/$entry", sub {
444 $nreq--;
445
446 if (-d _) {
447 push @dirs, $entry;
448
449 if (!--$ndirs) {
450 push @nondirs, @$entries;
451 $entries = [];
452 }
453 } else {
454 push @nondirs, $entry;
455 }
456
457 &$schedcb;
458 }
459 }
460 };
461
462 &$schedcb while @$entries && $nreq < $maxreq;
463 }; 676 };
464 }; 677 };
465 }; 678 };
679
680 $grp
466} 681}
467 682
468=item aio_fsync $fh, $callback->($status) 683=item aio_fsync $fh, $callback->($status)
469 684
470Asynchronously call fsync on the given filehandle and call the callback 685Asynchronously call fsync on the given filehandle and call the callback
476callback with the fdatasync result code. 691callback with the fdatasync result code.
477 692
478If this call isn't available because your OS lacks it or it couldn't be 693If this call isn't available because your OS lacks it or it couldn't be
479detected, it will be emulated by calling C<fsync> instead. 694detected, it will be emulated by calling C<fsync> instead.
480 695
696=item aio_group $callback->(...)
697
698This is a very special aio request: Instead of doing something, it is a
699container for other aio requests, which is useful if you want to bundle
700many requests into a single, composite, request with a definite callback
701and the ability to cancel the whole request with its subrequests.
702
703Returns an object of class L<IO::AIO::GRP>. See its documentation below
704for more info.
705
706Example:
707
708 my $grp = aio_group sub {
709 print "all stats done\n";
710 };
711
712 add $grp
713 (aio_stat ...),
714 (aio_stat ...),
715 ...;
716
717=item aio_nop $callback->()
718
719This is a special request - it does nothing in itself and is only used for
720side effects, such as when you want to add a dummy request to a group so
721that finishing the requests in the group depends on executing the given
722code.
723
724While this request does nothing, it still goes through the execution
725phase and still requires a worker thread. Thus, the callback will not
726be executed immediately but only after other requests in the queue have
727entered their execution phase. This can be used to measure request
728latency.
729
730=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
731
732Mainly used for debugging and benchmarking, this aio request puts one of
733the request workers to sleep for the given time.
734
735While it is theoretically handy to have simple I/O scheduling requests
736like sleep and file handle readable/writable, the overhead this creates is
737immense (it blocks a thread for a long time) so do not use this function
738except to put your application under artificial I/O pressure.
739
481=back 740=back
482 741
742=head2 IO::AIO::REQ CLASS
743
744All non-aggregate C<aio_*> functions return an object of this class when
745called in non-void context.
746
747=over 4
748
749=item cancel $req
750
751Cancels the request, if possible. Has the effect of skipping execution
752when entering the B<execute> state and skipping calling the callback when
753entering the the B<result> state, but will leave the request otherwise
754untouched. That means that requests that currently execute will not be
755stopped and resources held by the request will not be freed prematurely.
756
757=item cb $req $callback->(...)
758
759Replace (or simply set) the callback registered to the request.
760
761=back
762
763=head2 IO::AIO::GRP CLASS
764
765This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
766objects of this class, too.
767
768A IO::AIO::GRP object is a special request that can contain multiple other
769aio requests.
770
771You create one by calling the C<aio_group> constructing function with a
772callback that will be called when all contained requests have entered the
773C<done> state:
774
775 my $grp = aio_group sub {
776 print "all requests are done\n";
777 };
778
779You add requests by calling the C<add> method with one or more
780C<IO::AIO::REQ> objects:
781
782 $grp->add (aio_unlink "...");
783
784 add $grp aio_stat "...", sub {
785 $_[0] or return $grp->result ("error");
786
787 # add another request dynamically, if first succeeded
788 add $grp aio_open "...", sub {
789 $grp->result ("ok");
790 };
791 };
792
793This makes it very easy to create composite requests (see the source of
794C<aio_move> for an application) that work and feel like simple requests.
795
796=over 4
797
798=item * The IO::AIO::GRP objects will be cleaned up during calls to
799C<IO::AIO::poll_cb>, just like any other request.
800
801=item * They can be canceled like any other request. Canceling will cancel not
802only the request itself, but also all requests it contains.
803
804=item * They can also can also be added to other IO::AIO::GRP objects.
805
806=item * You must not add requests to a group from within the group callback (or
807any later time).
808
809=back
810
811Their lifetime, simplified, looks like this: when they are empty, they
812will finish very quickly. If they contain only requests that are in the
813C<done> state, they will also finish. Otherwise they will continue to
814exist.
815
816That means after creating a group you have some time to add requests. And
817in the callbacks of those requests, you can add further requests to the
818group. And only when all those requests have finished will the the group
819itself finish.
820
821=over 4
822
823=item add $grp ...
824
825=item $grp->add (...)
826
827Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
828be added, including other groups, as long as you do not create circular
829dependencies.
830
831Returns all its arguments.
832
833=item $grp->cancel_subs
834
835Cancel all subrequests and clears any feeder, but not the group request
836itself. Useful when you queued a lot of events but got a result early.
837
838=item $grp->result (...)
839
840Set the result value(s) that will be passed to the group callback when all
841subrequests have finished and set thre groups errno to the current value
842of errno (just like calling C<errno> without an error number). By default,
843no argument will be passed and errno is zero.
844
845=item $grp->errno ([$errno])
846
847Sets the group errno value to C<$errno>, or the current value of errno
848when the argument is missing.
849
850Every aio request has an associated errno value that is restored when
851the callback is invoked. This method lets you change this value from its
852default (0).
853
854Calling C<result> will also set errno, so make sure you either set C<$!>
855before the call to C<result>, or call c<errno> after it.
856
857=item feed $grp $callback->($grp)
858
859Sets a feeder/generator on this group: every group can have an attached
860generator that generates requests if idle. The idea behind this is that,
861although you could just queue as many requests as you want in a group,
862this might starve other requests for a potentially long time. For
863example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
864requests, delaying any later requests for a long time.
865
866To avoid this, and allow incremental generation of requests, you can
867instead a group and set a feeder on it that generates those requests. The
868feed callback will be called whenever there are few enough (see C<limit>,
869below) requests active in the group itself and is expected to queue more
870requests.
871
872The feed callback can queue as many requests as it likes (i.e. C<add> does
873not impose any limits).
874
875If the feed does not queue more requests when called, it will be
876automatically removed from the group.
877
878If the feed limit is C<0>, it will be set to C<2> automatically.
879
880Example:
881
882 # stat all files in @files, but only ever use four aio requests concurrently:
883
884 my $grp = aio_group sub { print "finished\n" };
885 limit $grp 4;
886 feed $grp sub {
887 my $file = pop @files
888 or return;
889
890 add $grp aio_stat $file, sub { ... };
891 };
892
893=item limit $grp $num
894
895Sets the feeder limit for the group: The feeder will be called whenever
896the group contains less than this many requests.
897
898Setting the limit to C<0> will pause the feeding process.
899
900=back
901
483=head2 SUPPORT FUNCTIONS 902=head2 SUPPORT FUNCTIONS
903
904=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
484 905
485=over 4 906=over 4
486 907
487=item $fileno = IO::AIO::poll_fileno 908=item $fileno = IO::AIO::poll_fileno
488 909
493 914
494See C<poll_cb> for an example. 915See C<poll_cb> for an example.
495 916
496=item IO::AIO::poll_cb 917=item IO::AIO::poll_cb
497 918
498Process all outstanding events on the result pipe. You have to call this 919Process some outstanding events on the result pipe. You have to call this
499regularly. Returns the number of events processed. Returns immediately 920regularly. Returns the number of events processed. Returns immediately
500when no events are outstanding. 921when no events are outstanding. The amount of events processed depends on
922the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
923
924If not all requests were processed for whatever reason, the filehandle
925will still be ready when C<poll_cb> returns.
501 926
502Example: Install an Event watcher that automatically calls 927Example: Install an Event watcher that automatically calls
503IO::AIO::poll_cb with high priority: 928IO::AIO::poll_cb with high priority:
504 929
505 Event->io (fd => IO::AIO::poll_fileno, 930 Event->io (fd => IO::AIO::poll_fileno,
506 poll => 'r', async => 1, 931 poll => 'r', async => 1,
507 cb => \&IO::AIO::poll_cb); 932 cb => \&IO::AIO::poll_cb);
508 933
934=item IO::AIO::max_poll_reqs $nreqs
935
936=item IO::AIO::max_poll_time $seconds
937
938These set the maximum number of requests (default C<0>, meaning infinity)
939that are being processed by C<IO::AIO::poll_cb> in one call, respectively
940the maximum amount of time (default C<0>, meaning infinity) spent in
941C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
942of time C<poll_cb> is allowed to use).
943
944Setting C<max_poll_time> to a non-zero value creates an overhead of one
945syscall per request processed, which is not normally a problem unless your
946callbacks are really really fast or your OS is really really slow (I am
947not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
948
949Setting these is useful if you want to ensure some level of
950interactiveness when perl is not fast enough to process all requests in
951time.
952
953For interactive programs, values such as C<0.01> to C<0.1> should be fine.
954
955Example: Install an Event watcher that automatically calls
956IO::AIO::poll_cb with low priority, to ensure that other parts of the
957program get the CPU sometimes even under high AIO load.
958
959 # try not to spend much more than 0.1s in poll_cb
960 IO::AIO::max_poll_time 0.1;
961
962 # use a low priority so other tasks have priority
963 Event->io (fd => IO::AIO::poll_fileno,
964 poll => 'r', nice => 1,
965 cb => &IO::AIO::poll_cb);
966
509=item IO::AIO::poll_wait 967=item IO::AIO::poll_wait
510 968
511Wait till the result filehandle becomes ready for reading (simply does a 969Wait till the result filehandle becomes ready for reading (simply does a
512C<select> on the filehandle. This is useful if you want to synchronously wait 970C<select> on the filehandle. This is useful if you want to synchronously
513for some requests to finish). 971wait for some requests to finish).
514 972
515See C<nreqs> for an example. 973See C<nreqs> for an example.
516 974
975=item IO::AIO::poll
976
977Waits until some requests have been handled.
978
979Strictly equivalent to:
980
981 IO::AIO::poll_wait, IO::AIO::poll_cb
982 if IO::AIO::nreqs;
983
517=item IO::AIO::nreqs 984=item IO::AIO::flush
518 985
519Returns the number of requests currently outstanding (i.e. for which their 986Wait till all outstanding AIO requests have been handled.
520callback has not been invoked yet).
521 987
522Example: wait till there are no outstanding requests anymore: 988Strictly equivalent to:
523 989
524 IO::AIO::poll_wait, IO::AIO::poll_cb 990 IO::AIO::poll_wait, IO::AIO::poll_cb
525 while IO::AIO::nreqs; 991 while IO::AIO::nreqs;
526 992
527=item IO::AIO::flush 993=head3 CONTROLLING THE NUMBER OF THREADS
528
529Wait till all outstanding AIO requests have been handled.
530
531Strictly equivalent to:
532
533 IO::AIO::poll_wait, IO::AIO::poll_cb
534 while IO::AIO::nreqs;
535
536=item IO::AIO::poll
537
538Waits until some requests have been handled.
539
540Strictly equivalent to:
541
542 IO::AIO::poll_wait, IO::AIO::poll_cb
543 if IO::AIO::nreqs;
544 994
545=item IO::AIO::min_parallel $nthreads 995=item IO::AIO::min_parallel $nthreads
546 996
547Set the minimum number of AIO threads to C<$nthreads>. The current default 997Set the minimum number of AIO threads to C<$nthreads>. The current
548is C<4>, which means four asynchronous operations can be done at one time 998default is C<8>, which means eight asynchronous operations can execute
549(the number of outstanding operations, however, is unlimited). 999concurrently at any one time (the number of outstanding requests,
1000however, is unlimited).
550 1001
551IO::AIO starts threads only on demand, when an AIO request is queued and 1002IO::AIO starts threads only on demand, when an AIO request is queued and
552no free thread exists. 1003no free thread exists. Please note that queueing up a hundred requests can
1004create demand for a hundred threads, even if it turns out that everything
1005is in the cache and could have been processed faster by a single thread.
553 1006
554It is recommended to keep the number of threads low, as some Linux 1007It is recommended to keep the number of threads relatively low, as some
555kernel versions will scale negatively with the number of threads (higher 1008Linux kernel versions will scale negatively with the number of threads
556parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 1009(higher parallelity => MUCH higher latency). With current Linux 2.6
557threads should be fine. 1010versions, 4-32 threads should be fine.
558 1011
559Under most circumstances you don't need to call this function, as the 1012Under most circumstances you don't need to call this function, as the
560module selects a default that is suitable for low to moderate load. 1013module selects a default that is suitable for low to moderate load.
561 1014
562=item IO::AIO::max_parallel $nthreads 1015=item IO::AIO::max_parallel $nthreads
571This module automatically runs C<max_parallel 0> at program end, to ensure 1024This module automatically runs C<max_parallel 0> at program end, to ensure
572that all threads are killed and that there are no outstanding requests. 1025that all threads are killed and that there are no outstanding requests.
573 1026
574Under normal circumstances you don't need to call this function. 1027Under normal circumstances you don't need to call this function.
575 1028
1029=item IO::AIO::max_idle $nthreads
1030
1031Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1032threads that did not get a request to process within 10 seconds). That
1033means if a thread becomes idle while C<$nthreads> other threads are also
1034idle, it will free its resources and exit.
1035
1036This is useful when you allow a large number of threads (e.g. 100 or 1000)
1037to allow for extremely high load situations, but want to free resources
1038under normal circumstances (1000 threads can easily consume 30MB of RAM).
1039
1040The default is probably ok in most situations, especially if thread
1041creation is fast. If thread creation is very slow on your system you might
1042want to use larger values.
1043
576=item $oldnreqs = IO::AIO::max_outstanding $nreqs 1044=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
1045
1046This is a very bad function to use in interactive programs because it
1047blocks, and a bad way to reduce concurrency because it is inexact: Better
1048use an C<aio_group> together with a feed callback.
577 1049
578Sets the maximum number of outstanding requests to C<$nreqs>. If you 1050Sets the maximum number of outstanding requests to C<$nreqs>. If you
579try to queue up more than this number of requests, the caller will block until 1051to queue up more than this number of requests, the next call to the
580some requests have been handled. 1052C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1053function will block until the limit is no longer exceeded.
581 1054
582The default is very large, so normally there is no practical limit. If you 1055The default value is very large, so there is no practical limit on the
583queue up many requests in a loop it often improves speed if you set 1056number of outstanding requests.
584this to a relatively low number, such as C<100>.
585 1057
586Under normal circumstances you don't need to call this function. 1058You can still queue as many requests as you want. Therefore,
1059C<max_oustsanding> is mainly useful in simple scripts (with low values) or
1060as a stop gap to shield against fatal memory overflow (with large values).
1061
1062=head3 STATISTICAL INFORMATION
1063
1064=item IO::AIO::nreqs
1065
1066Returns the number of requests currently in the ready, execute or pending
1067states (i.e. for which their callback has not been invoked yet).
1068
1069Example: wait till there are no outstanding requests anymore:
1070
1071 IO::AIO::poll_wait, IO::AIO::poll_cb
1072 while IO::AIO::nreqs;
1073
1074=item IO::AIO::nready
1075
1076Returns the number of requests currently in the ready state (not yet
1077executed).
1078
1079=item IO::AIO::npending
1080
1081Returns the number of requests currently in the pending state (executed,
1082but not yet processed by poll_cb).
587 1083
588=back 1084=back
589 1085
590=cut 1086=cut
591 1087
603 or return undef; 1099 or return undef;
604 1100
605 *$sym 1101 *$sym
606} 1102}
607 1103
608min_parallel 4; 1104min_parallel 8;
609 1105
610END { 1106END {
611 max_parallel 0; 1107 min_parallel 1;
612} 1108 flush;
1109};
613 1110
6141; 11111;
615 1112
616=head2 FORK BEHAVIOUR 1113=head2 FORK BEHAVIOUR
1114
1115This module should do "the right thing" when the process using it forks:
617 1116
618Before the fork, IO::AIO enters a quiescent state where no requests 1117Before the fork, IO::AIO enters a quiescent state where no requests
619can be added in other threads and no results will be processed. After 1118can be added in other threads and no results will be processed. After
620the fork the parent simply leaves the quiescent state and continues 1119the fork the parent simply leaves the quiescent state and continues
621request/result processing, while the child clears the request/result 1120request/result processing, while the child frees the request/result queue
622queue (so the requests started before the fork will only be handled in 1121(so that the requests started before the fork will only be handled in the
623the parent). Threats will be started on demand until the limit ste in the 1122parent). Threads will be started on demand until the limit set in the
624parent process has been reached again. 1123parent process has been reached again.
625 1124
1125In short: the parent will, after a short pause, continue as if fork had
1126not been called, while the child will act as if IO::AIO has not been used
1127yet.
1128
1129=head2 MEMORY USAGE
1130
1131Per-request usage:
1132
1133Each aio request uses - depending on your architecture - around 100-200
1134bytes of memory. In addition, stat requests need a stat buffer (possibly
1135a few hundred bytes), readdir requires a result buffer and so on. Perl
1136scalars and other data passed into aio requests will also be locked and
1137will consume memory till the request has entered the done state.
1138
1139This is now awfully much, so queuing lots of requests is not usually a
1140problem.
1141
1142Per-thread usage:
1143
1144In the execution phase, some aio requests require more memory for
1145temporary buffers, and each thread requires a stack and other data
1146structures (usually around 16k-128k, depending on the OS).
1147
1148=head1 KNOWN BUGS
1149
1150Known bugs will be fixed in the next release.
1151
626=head1 SEE ALSO 1152=head1 SEE ALSO
627 1153
628L<Coro>, L<Linux::AIO>. 1154L<Coro::AIO>.
629 1155
630=head1 AUTHOR 1156=head1 AUTHOR
631 1157
632 Marc Lehmann <schmorp@schmorp.de> 1158 Marc Lehmann <schmorp@schmorp.de>
633 http://home.schmorp.de/ 1159 http://home.schmorp.de/

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