ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/IO-AIO/AIO.pm
(Generate patch)

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 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 use IO::AIO 2; # version has aio objects 20 # version 2+ has request and group objects
21 use IO::AIO 2;
21 22
23 aioreq_pri 4; # give next request a very high priority
22 my $req = aio_unlink "/tmp/file", sub { }; 24 my $req = aio_unlink "/tmp/file", sub { };
23 $req->cancel; # cancel request if still in queue 25 $req->cancel; # cancel request if still in queue
24 26
25 # AnyEvent 27 my $grp = aio_group sub { print "all stats done\n" };
28 add $grp aio_stat "..." for ...;
29
30 # AnyEvent integration
26 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; 31 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
27 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 });
28 33
29 # Event 34 # Event integration
30 Event->io (fd => IO::AIO::poll_fileno, 35 Event->io (fd => IO::AIO::poll_fileno,
31 poll => 'r', 36 poll => 'r',
32 cb => \&IO::AIO::poll_cb); 37 cb => \&IO::AIO::poll_cb);
33 38
34 # Glib/Gtk2 39 # Glib/Gtk2 integration
35 add_watch Glib::IO IO::AIO::poll_fileno, 40 add_watch Glib::IO IO::AIO::poll_fileno,
36 in => sub { IO::AIO::poll_cb; 1 }; 41 in => sub { IO::AIO::poll_cb; 1 };
37 42
38 # Tk 43 # Tk integration
39 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", 44 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
40 readable => \&IO::AIO::poll_cb); 45 readable => \&IO::AIO::poll_cb);
41 46
42 # Danga::Socket 47 # Danga::Socket integration
43 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 48 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
44 \&IO::AIO::poll_cb); 49 \&IO::AIO::poll_cb);
45 50
46
47=head1 DESCRIPTION 51=head1 DESCRIPTION
48 52
49This module implements asynchronous I/O using whatever means your 53This module implements asynchronous I/O using whatever means your
50operating system supports. 54operating system supports.
51 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
52Currently, a number of threads are started that execute your read/writes 72In this version, a number of threads are started that execute your
53and signal their completion. You don't need thread support in your libc or 73requests and signal their completion. You don't need thread support
54perl, 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
55pthreads 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
56aio functions available on many operating systems. However, they are often 76functions available on many operating systems. However, they are often
57not well-supported (Linux doesn't allow them on normal files currently, 77not well-supported or restricted (GNU/Linux doesn't allow them on normal
58for 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
59remaining functionality would have to be implemented using threads anyway. 79aio_write, so the remaining functionality would have to be implemented
80using threads anyway.
60 81
61Although 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-)
62currently not reentrant, so use appropriate locking yourself, always call 83threads, it is currently not reentrant in any way, so use appropriate
63C<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
64C<aio_> functions) recursively. 85never call C<poll_cb> (or other C<aio_> functions) recursively.
86
87=head1 REQUEST ANATOMY AND LIFETIME
88
89Every C<aio_*> function creates a request. which is a C data structure not
90directly visible to Perl.
91
92If called in non-void context, every request function returns a Perl
93object representing the request. In void context, nothing is returned,
94which saves a bit of memory.
95
96The perl object is a fairly standard ref-to-hash object. The hash contents
97are not used by IO::AIO so you are free to store anything you like in it.
98
99During their existance, aio requests travel through the following states,
100in order:
101
102=over 4
103
104=item ready
105
106Immediately after a request is created it is put into the ready state,
107waiting for a thread to execute it.
108
109=item execute
110
111A thread has accepted the request for processing and is currently
112executing it (e.g. blocking in read).
113
114=item pending
115
116The request has been executed and is waiting for result processing.
117
118While request submission and execution is fully asynchronous, result
119processing is not and relies on the perl interpreter calling C<poll_cb>
120(or another function with the same effect).
121
122=item result
123
124The request results are processed synchronously by C<poll_cb>.
125
126The C<poll_cb> function will process all outstanding aio requests by
127calling their callbacks, freeing memory associated with them and managing
128any groups they are contained in.
129
130=item done
131
132Request has reached the end of its lifetime and holds no resources anymore
133(except possibly for the Perl object, but its connection to the actual
134aio request is severed and calling its methods will either do nothing or
135result in a runtime error).
65 136
66=cut 137=cut
67 138
68package IO::AIO; 139package IO::AIO;
69 140
71use strict 'vars'; 142use strict 'vars';
72 143
73use base 'Exporter'; 144use base 'Exporter';
74 145
75BEGIN { 146BEGIN {
76 our $VERSION = '1.99'; 147 our $VERSION = '2.0';
77 148
78 our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 149 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
79 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 150 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 151 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
81 aio_group); 152 aio_copy aio_group aio_nop aio_mknod);
82 our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); 153 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
154 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
155 min_parallel max_parallel nreqs nready npending);
83 156
84 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 157 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
85 158
86 require XSLoader; 159 require XSLoader;
87 XSLoader::load ("IO::AIO", $VERSION); 160 XSLoader::load ("IO::AIO", $VERSION);
100syscall has been executed asynchronously. 173syscall has been executed asynchronously.
101 174
102All functions expecting a filehandle keep a copy of the filehandle 175All functions expecting a filehandle keep a copy of the filehandle
103internally until the request has finished. 176internally until the request has finished.
104 177
105All non-composite requests (requests that are not broken down into
106multiple requests) return objects of type L<IO::AIO::REQ> that allow 178All requests return objects of type L<IO::AIO::REQ> that allow further
107further manipulation of running requests. 179manipulation of those requests while they are in-flight.
108 180
109The pathnames you pass to these routines I<must> be absolute and 181The pathnames you pass to these routines I<must> be absolute and
110encoded in byte form. The reason for the former is that at the time the 182encoded in byte form. The reason for the former is that at the time the
111request is being executed, the current working directory could have 183request is being executed, the current working directory could have
112changed. Alternatively, you can make sure that you never change the 184changed. Alternatively, you can make sure that you never change the
118your pathnames to the locale (or other) encoding in effect in the user 190your pathnames to the locale (or other) encoding in effect in the user
119environment, d) use Glib::filename_from_unicode on unicode filenames or e) 191environment, d) use Glib::filename_from_unicode on unicode filenames or e)
120use something else. 192use something else.
121 193
122=over 4 194=over 4
195
196=item $prev_pri = aioreq_pri [$pri]
197
198Returns the priority value that would be used for the next request and, if
199C<$pri> is given, sets the priority for the next aio request.
200
201The default priority is C<0>, the minimum and maximum priorities are C<-4>
202and C<4>, respectively. Requests with higher priority will be serviced
203first.
204
205The priority will be reset to C<0> after each call to one of the C<aio_*>
206functions.
207
208Example: open a file with low priority, then read something from it with
209higher priority so the read request is serviced before other low priority
210open requests (potentially spamming the cache):
211
212 aioreq_pri -3;
213 aio_open ..., sub {
214 return unless $_[0];
215
216 aioreq_pri -2;
217 aio_read $_[0], ..., sub {
218 ...
219 };
220 };
221
222=item aioreq_nice $pri_adjust
223
224Similar to C<aioreq_pri>, but subtracts the given value from the current
225priority, so effects are cumulative.
123 226
124=item aio_open $pathname, $flags, $mode, $callback->($fh) 227=item aio_open $pathname, $flags, $mode, $callback->($fh)
125 228
126Asynchronously open or create a file and call the callback with a newly 229Asynchronously open or create a file and call the callback with a newly
127created filehandle for the file. 230created filehandle for the file.
177 280
178 aio_read $fh, 7, 15, $buffer, 0, sub { 281 aio_read $fh, 7, 15, $buffer, 0, sub {
179 $_[0] > 0 or die "read error: $!"; 282 $_[0] > 0 or die "read error: $!";
180 print "read $_[0] bytes: <$buffer>\n"; 283 print "read $_[0] bytes: <$buffer>\n";
181 }; 284 };
182
183=item aio_move $srcpath, $dstpath, $callback->($status)
184
185Try to move the I<file> (directories not supported as either source or
186destination) from C<$srcpath> to C<$dstpath> and call the callback with
187the C<0> (error) or C<-1> ok.
188
189This is a composite request that tries to rename(2) the file first. If
190rename files with C<EXDEV>, it creates the destination file with mode 0200
191and copies the contents of the source file into it using C<aio_sendfile>,
192followed by restoring atime, mtime, access mode and uid/gid, in that
193order, and unlinking the C<$srcpath>.
194
195If an error occurs, the partial destination file will be unlinked, if
196possible, except when setting atime, mtime, access mode and uid/gid, where
197errors are being ignored.
198
199=cut
200
201sub aio_move($$$) {
202 my ($src, $dst, $cb) = @_;
203
204 aio_rename $src, $dst, sub {
205 if ($_[0] && $! == EXDEV) {
206 aio_open $src, O_RDONLY, 0, sub {
207 if (my $src_fh = $_[0]) {
208 my @stat = stat $src_fh;
209
210 aio_open $dst, O_WRONLY, 0200, sub {
211 if (my $dst_fh = $_[0]) {
212 aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
213 close $src_fh;
214
215 if ($_[0] == $stat[7]) {
216 utime $stat[8], $stat[9], $dst;
217 chmod $stat[2] & 07777, $dst_fh;
218 chown $stat[4], $stat[5], $dst_fh;
219 close $dst_fh;
220
221 aio_unlink $src, sub {
222 $cb->($_[0]);
223 };
224 } else {
225 my $errno = $!;
226 aio_unlink $dst, sub {
227 $! = $errno;
228 $cb->(-1);
229 };
230 }
231 };
232 } else {
233 $cb->(-1);
234 }
235 },
236
237 } else {
238 $cb->(-1);
239 }
240 };
241 } else {
242 $cb->($_[0]);
243 }
244 };
245}
246 285
247=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 286=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
248 287
249Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 288Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
250reading at byte offset C<$in_offset>, and starts writing at the current 289reading at byte offset C<$in_offset>, and starts writing at the current
306=item aio_unlink $pathname, $callback->($status) 345=item aio_unlink $pathname, $callback->($status)
307 346
308Asynchronously unlink (delete) a file and call the callback with the 347Asynchronously unlink (delete) a file and call the callback with the
309result code. 348result code.
310 349
350=item aio_mknod $path, $mode, $dev, $callback->($status)
351
352Asynchronously create a device node (or fifo). See mknod(2).
353
354The only portable (POSIX) way of calling this function is:
355
356 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
357
311=item aio_link $srcpath, $dstpath, $callback->($status) 358=item aio_link $srcpath, $dstpath, $callback->($status)
312 359
313Asynchronously create a new link to the existing object at C<$srcpath> at 360Asynchronously create a new link to the existing object at C<$srcpath> at
314the path C<$dstpath> and call the callback with the result code. 361the path C<$dstpath> and call the callback with the result code.
315 362
335sorted, and will B<NOT> include the C<.> and C<..> entries. 382sorted, and will B<NOT> include the C<.> and C<..> entries.
336 383
337The callback a single argument which is either C<undef> or an array-ref 384The callback a single argument which is either C<undef> or an array-ref
338with the filenames. 385with the filenames.
339 386
387=item aio_copy $srcpath, $dstpath, $callback->($status)
388
389Try to copy the I<file> (directories not supported as either source or
390destination) from C<$srcpath> to C<$dstpath> and call the callback with
391the C<0> (error) or C<-1> ok.
392
393This is a composite request that it creates the destination file with
394mode 0200 and copies the contents of the source file into it using
395C<aio_sendfile>, followed by restoring atime, mtime, access mode and
396uid/gid, in that order.
397
398If an error occurs, the partial destination file will be unlinked, if
399possible, except when setting atime, mtime, access mode and uid/gid, where
400errors are being ignored.
401
402=cut
403
404sub aio_copy($$;$) {
405 my ($src, $dst, $cb) = @_;
406
407 my $pri = aioreq_pri;
408 my $grp = aio_group $cb;
409
410 aioreq_pri $pri;
411 add $grp aio_open $src, O_RDONLY, 0, sub {
412 if (my $src_fh = $_[0]) {
413 my @stat = stat $src_fh;
414
415 aioreq_pri $pri;
416 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
417 if (my $dst_fh = $_[0]) {
418 aioreq_pri $pri;
419 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
420 if ($_[0] == $stat[7]) {
421 $grp->result (0);
422 close $src_fh;
423
424 # those should not normally block. should. should.
425 utime $stat[8], $stat[9], $dst;
426 chmod $stat[2] & 07777, $dst_fh;
427 chown $stat[4], $stat[5], $dst_fh;
428 close $dst_fh;
429 } else {
430 $grp->result (-1);
431 close $src_fh;
432 close $dst_fh;
433
434 aioreq $pri;
435 add $grp aio_unlink $dst;
436 }
437 };
438 } else {
439 $grp->result (-1);
440 }
441 },
442
443 } else {
444 $grp->result (-1);
445 }
446 };
447
448 $grp
449}
450
451=item aio_move $srcpath, $dstpath, $callback->($status)
452
453Try to move the I<file> (directories not supported as either source or
454destination) from C<$srcpath> to C<$dstpath> and call the callback with
455the C<0> (error) or C<-1> ok.
456
457This is a composite request that tries to rename(2) the file first. If
458rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
459that is successful, unlinking the C<$srcpath>.
460
461=cut
462
463sub aio_move($$;$) {
464 my ($src, $dst, $cb) = @_;
465
466 my $pri = aioreq_pri;
467 my $grp = aio_group $cb;
468
469 aioreq_pri $pri;
470 add $grp aio_rename $src, $dst, sub {
471 if ($_[0] && $! == EXDEV) {
472 aioreq_pri $pri;
473 add $grp aio_copy $src, $dst, sub {
474 $grp->result ($_[0]);
475
476 if (!$_[0]) {
477 aioreq_pri $pri;
478 add $grp aio_unlink $src;
479 }
480 };
481 } else {
482 $grp->result ($_[0]);
483 }
484 };
485
486 $grp
487}
488
340=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 489=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
341 490
342Scans a directory (similar to C<aio_readdir>) but additionally tries to 491Scans a directory (similar to C<aio_readdir>) but additionally tries to
343separate the entries of directory C<$path> into two sets of names, ones 492efficiently separate the entries of directory C<$path> into two sets of
344you can recurse into (directories or links to them), and ones you cannot 493names, directories you can recurse into (directories), and ones you cannot
345recurse into (everything else). 494recurse into (everything else, including symlinks to directories).
346 495
347C<aio_scandir> is a composite request that consists of many sub 496C<aio_scandir> is a composite request that creates of many sub requests_
348requests. C<$maxreq> specifies the maximum number of outstanding aio 497C<$maxreq> specifies the maximum number of outstanding aio requests that
349requests that this function generates. If it is C<< <= 0 >>, then a 498this function generates. If it is C<< <= 0 >>, then a suitable default
350suitable default will be chosen (currently 8). 499will be chosen (currently 4).
351 500
352On error, the callback is called without arguments, otherwise it receives 501On error, the callback is called without arguments, otherwise it receives
353two array-refs with path-relative entry names. 502two array-refs with path-relative entry names.
354 503
355Example: 504Example:
392=cut 541=cut
393 542
394sub aio_scandir($$$) { 543sub aio_scandir($$$) {
395 my ($path, $maxreq, $cb) = @_; 544 my ($path, $maxreq, $cb) = @_;
396 545
546 my $pri = aioreq_pri;
547
548 my $grp = aio_group $cb;
549
397 $maxreq = 8 if $maxreq <= 0; 550 $maxreq = 4 if $maxreq <= 0;
398 551
399 # stat once 552 # stat once
553 aioreq_pri $pri;
400 aio_stat $path, sub { 554 add $grp aio_stat $path, sub {
401 return $cb->() if $_[0]; 555 return $grp->result () if $_[0];
402 my $now = time; 556 my $now = time;
403 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 557 my $hash1 = join ":", (stat _)[0,1,3,7,9];
404 558
405 # read the directory entries 559 # read the directory entries
560 aioreq_pri $pri;
406 aio_readdir $path, sub { 561 add $grp aio_readdir $path, sub {
407 my $entries = shift 562 my $entries = shift
408 or return $cb->(); 563 or return $grp->result ();
409 564
410 # stat the dir another time 565 # stat the dir another time
566 aioreq_pri $pri;
411 aio_stat $path, sub { 567 add $grp aio_stat $path, sub {
412 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 568 my $hash2 = join ":", (stat _)[0,1,3,7,9];
413 569
414 my $ndirs; 570 my $ndirs;
415 571
416 # take the slow route if anything looks fishy 572 # take the slow route if anything looks fishy
418 $ndirs = -1; 574 $ndirs = -1;
419 } else { 575 } else {
420 # if nlink == 2, we are finished 576 # if nlink == 2, we are finished
421 # on non-posix-fs's, we rely on nlink < 2 577 # on non-posix-fs's, we rely on nlink < 2
422 $ndirs = (stat _)[3] - 2 578 $ndirs = (stat _)[3] - 2
423 or return $cb->([], $entries); 579 or return $grp->result ([], $entries);
424 } 580 }
425 581
426 # sort into likely dirs and likely nondirs 582 # sort into likely dirs and likely nondirs
427 # dirs == files without ".", short entries first 583 # dirs == files without ".", short entries first
428 $entries = [map $_->[0], 584 $entries = [map $_->[0],
430 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 586 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
431 @$entries]; 587 @$entries];
432 588
433 my (@dirs, @nondirs); 589 my (@dirs, @nondirs);
434 590
435 my ($statcb, $schedcb); 591 my $statgrp = add $grp aio_group sub {
436 my $nreq = 0; 592 $grp->result (\@dirs, \@nondirs);
593 };
437 594
438 $schedcb = sub { 595 limit $statgrp $maxreq;
439 if (@$entries) { 596 feed $statgrp sub {
440 if ($nreq < $maxreq) { 597 return unless @$entries;
441 my $ent = pop @$entries; 598 my $entry = pop @$entries;
599
600 aioreq_pri $pri;
601 add $statgrp aio_stat "$path/$entry/.", sub {
602 if ($_[0] < 0) {
603 push @nondirs, $entry;
604 } else {
605 # need to check for real directory
606 aioreq_pri $pri;
607 add $statgrp aio_lstat "$path/$entry", sub {
608 if (-d _) {
609 push @dirs, $entry;
610
611 unless (--$ndirs) {
612 push @nondirs, @$entries;
613 feed $statgrp;
614 }
615 } else {
616 push @nondirs, $entry;
617 }
442 $nreq++; 618 }
443 aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
444 } 619 }
445 } elsif (!$nreq) {
446 # finished
447 undef $statcb;
448 undef $schedcb;
449 $cb->(\@dirs, \@nondirs) if $cb;
450 undef $cb;
451 } 620 };
452 }; 621 };
453 $statcb = sub {
454 my ($status, $entry) = @_;
455
456 if ($status < 0) {
457 $nreq--;
458 push @nondirs, $entry;
459 &$schedcb;
460 } else {
461 # need to check for real directory
462 aio_lstat "$path/$entry", sub {
463 $nreq--;
464
465 if (-d _) {
466 push @dirs, $entry;
467
468 if (!--$ndirs) {
469 push @nondirs, @$entries;
470 $entries = [];
471 }
472 } else {
473 push @nondirs, $entry;
474 }
475
476 &$schedcb;
477 }
478 }
479 };
480
481 &$schedcb while @$entries && $nreq < $maxreq;
482 }; 622 };
483 }; 623 };
484 }; 624 };
625
626 $grp
485} 627}
486 628
487=item aio_fsync $fh, $callback->($status) 629=item aio_fsync $fh, $callback->($status)
488 630
489Asynchronously call fsync on the given filehandle and call the callback 631Asynchronously call fsync on the given filehandle and call the callback
495callback with the fdatasync result code. 637callback with the fdatasync result code.
496 638
497If this call isn't available because your OS lacks it or it couldn't be 639If this call isn't available because your OS lacks it or it couldn't be
498detected, it will be emulated by calling C<fsync> instead. 640detected, it will be emulated by calling C<fsync> instead.
499 641
500=item aio_group $callback->() 642=item aio_group $callback->(...)
501 643
644This is a very special aio request: Instead of doing something, it is a
645container for other aio requests, which is useful if you want to bundle
646many requests into a single, composite, request with a definite callback
647and the ability to cancel the whole request with its subrequests.
648
649Returns an object of class L<IO::AIO::GRP>. See its documentation below
650for more info.
651
652Example:
653
654 my $grp = aio_group sub {
655 print "all stats done\n";
656 };
657
658 add $grp
659 (aio_stat ...),
660 (aio_stat ...),
661 ...;
662
663=item aio_nop $callback->()
664
665This is a special request - it does nothing in itself and is only used for
666side effects, such as when you want to add a dummy request to a group so
667that finishing the requests in the group depends on executing the given
668code.
669
670While this request does nothing, it still goes through the execution
671phase and still requires a worker thread. Thus, the callback will not
672be executed immediately but only after other requests in the queue have
673entered their execution phase. This can be used to measure request
674latency.
675
502=item aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED* 676=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
503 677
504Mainly used for debugging and benchmarking, this aio request puts one of 678Mainly used for debugging and benchmarking, this aio request puts one of
505the request workers to sleep for the given time. 679the request workers to sleep for the given time.
506 680
681While it is theoretically handy to have simple I/O scheduling requests
682like sleep and file handle readable/writable, the overhead this creates is
683immense (it blocks a thread for a long time) so do not use this function
684except to put your application under artificial I/O pressure.
685
507=back 686=back
508 687
509=head2 IO::AIO::REQ CLASS 688=head2 IO::AIO::REQ CLASS
510 689
511All non-aggregate C<aio_*> functions return an object of this class when 690All non-aggregate C<aio_*> functions return an object of this class when
512called in non-void context. 691called in non-void context.
513 692
514A request always moves through the following five states in its lifetime,
515in order: B<ready> (request has been created, but has not been executed
516yet), B<execute> (request is currently being executed), B<pending>
517(request has been executed but callback has not been called yet),
518B<result> (results are being processed synchronously, includes calling the
519callback) and B<done> (request has reached the end of its lifetime and
520holds no resources anymore).
521
522=over 4 693=over 4
523 694
524=item $req->cancel 695=item cancel $req
525 696
526Cancels the request, if possible. Has the effect of skipping execution 697Cancels the request, if possible. Has the effect of skipping execution
527when entering the B<execute> state and skipping calling the callback when 698when entering the B<execute> state and skipping calling the callback when
528entering the the B<result> state, but will leave the request otherwise 699entering the the B<result> state, but will leave the request otherwise
529untouched. That means that requests that currently execute will not be 700untouched. That means that requests that currently execute will not be
530stopped and resources held by the request will not be freed prematurely. 701stopped and resources held by the request will not be freed prematurely.
531 702
703=item cb $req $callback->(...)
704
705Replace (or simply set) the callback registered to the request.
706
707=back
708
709=head2 IO::AIO::GRP CLASS
710
711This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
712objects of this class, too.
713
714A IO::AIO::GRP object is a special request that can contain multiple other
715aio requests.
716
717You create one by calling the C<aio_group> constructing function with a
718callback that will be called when all contained requests have entered the
719C<done> state:
720
721 my $grp = aio_group sub {
722 print "all requests are done\n";
723 };
724
725You add requests by calling the C<add> method with one or more
726C<IO::AIO::REQ> objects:
727
728 $grp->add (aio_unlink "...");
729
730 add $grp aio_stat "...", sub {
731 $_[0] or return $grp->result ("error");
732
733 # add another request dynamically, if first succeeded
734 add $grp aio_open "...", sub {
735 $grp->result ("ok");
736 };
737 };
738
739This makes it very easy to create composite requests (see the source of
740C<aio_move> for an application) that work and feel like simple requests.
741
742=over 4
743
744=item * The IO::AIO::GRP objects will be cleaned up during calls to
745C<IO::AIO::poll_cb>, just like any other request.
746
747=item * They can be canceled like any other request. Canceling will cancel not
748only the request itself, but also all requests it contains.
749
750=item * They can also can also be added to other IO::AIO::GRP objects.
751
752=item * You must not add requests to a group from within the group callback (or
753any later time).
754
755=back
756
757Their lifetime, simplified, looks like this: when they are empty, they
758will finish very quickly. If they contain only requests that are in the
759C<done> state, they will also finish. Otherwise they will continue to
760exist.
761
762That means after creating a group you have some time to add requests. And
763in the callbacks of those requests, you can add further requests to the
764group. And only when all those requests have finished will the the group
765itself finish.
766
767=over 4
768
769=item add $grp ...
770
771=item $grp->add (...)
772
773Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
774be added, including other groups, as long as you do not create circular
775dependencies.
776
777Returns all its arguments.
778
779=item $grp->cancel_subs
780
781Cancel all subrequests and clears any feeder, but not the group request
782itself. Useful when you queued a lot of events but got a result early.
783
784=item $grp->result (...)
785
786Set the result value(s) that will be passed to the group callback when all
787subrequests have finished and set thre groups errno to the current value
788of errno (just like calling C<errno> without an error number). By default,
789no argument will be passed and errno is zero.
790
791=item $grp->errno ([$errno])
792
793Sets the group errno value to C<$errno>, or the current value of errno
794when the argument is missing.
795
796Every aio request has an associated errno value that is restored when
797the callback is invoked. This method lets you change this value from its
798default (0).
799
800Calling C<result> will also set errno, so make sure you either set C<$!>
801before the call to C<result>, or call c<errno> after it.
802
803=item feed $grp $callback->($grp)
804
805Sets a feeder/generator on this group: every group can have an attached
806generator that generates requests if idle. The idea behind this is that,
807although you could just queue as many requests as you want in a group,
808this might starve other requests for a potentially long time. For
809example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
810requests, delaying any later requests for a long time.
811
812To avoid this, and allow incremental generation of requests, you can
813instead a group and set a feeder on it that generates those requests. The
814feed callback will be called whenever there are few enough (see C<limit>,
815below) requests active in the group itself and is expected to queue more
816requests.
817
818The feed callback can queue as many requests as it likes (i.e. C<add> does
819not impose any limits).
820
821If the feed does not queue more requests when called, it will be
822automatically removed from the group.
823
824If the feed limit is C<0>, it will be set to C<2> automatically.
825
826Example:
827
828 # stat all files in @files, but only ever use four aio requests concurrently:
829
830 my $grp = aio_group sub { print "finished\n" };
831 limit $grp 4;
832 feed $grp sub {
833 my $file = pop @files
834 or return;
835
836 add $grp aio_stat $file, sub { ... };
837 };
838
839=item limit $grp $num
840
841Sets the feeder limit for the group: The feeder will be called whenever
842the group contains less than this many requests.
843
844Setting the limit to C<0> will pause the feeding process.
845
532=back 846=back
533 847
534=head2 SUPPORT FUNCTIONS 848=head2 SUPPORT FUNCTIONS
535 849
536=over 4 850=over 4
548 862
549Process all outstanding events on the result pipe. You have to call this 863Process all outstanding events on the result pipe. You have to call this
550regularly. Returns the number of events processed. Returns immediately 864regularly. Returns the number of events processed. Returns immediately
551when no events are outstanding. 865when no events are outstanding.
552 866
867If not all requests were processed for whatever reason, the filehandle
868will still be ready when C<poll_cb> returns.
869
553Example: Install an Event watcher that automatically calls 870Example: Install an Event watcher that automatically calls
554IO::AIO::poll_cb with high priority: 871IO::AIO::poll_cb with high priority:
555 872
556 Event->io (fd => IO::AIO::poll_fileno, 873 Event->io (fd => IO::AIO::poll_fileno,
557 poll => 'r', async => 1, 874 poll => 'r', async => 1,
558 cb => \&IO::AIO::poll_cb); 875 cb => \&IO::AIO::poll_cb);
559 876
877=item IO::AIO::poll_some $max_requests
878
879Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
880at a time.
881
882Useful if you want to ensure some level of interactiveness when perl is
883not fast enough to process all requests in time.
884
885Example: Install an Event watcher that automatically calls
886IO::AIO::poll_some with low priority, to ensure that other parts of the
887program get the CPU sometimes even under high AIO load.
888
889 Event->io (fd => IO::AIO::poll_fileno,
890 poll => 'r', nice => 1,
891 cb => sub { IO::AIO::poll_some 256 });
892
560=item IO::AIO::poll_wait 893=item IO::AIO::poll_wait
561 894
562Wait till the result filehandle becomes ready for reading (simply does a 895Wait till the result filehandle becomes ready for reading (simply does a
563C<select> on the filehandle. This is useful if you want to synchronously wait 896C<select> on the filehandle. This is useful if you want to synchronously wait
564for some requests to finish). 897for some requests to finish).
565 898
566See C<nreqs> for an example. 899See C<nreqs> for an example.
567 900
568=item IO::AIO::nreqs 901=item IO::AIO::nreqs
569 902
570Returns the number of requests currently outstanding (i.e. for which their 903Returns the number of requests currently in the ready, execute or pending
571callback has not been invoked yet). 904states (i.e. for which their callback has not been invoked yet).
572 905
573Example: wait till there are no outstanding requests anymore: 906Example: wait till there are no outstanding requests anymore:
574 907
575 IO::AIO::poll_wait, IO::AIO::poll_cb 908 IO::AIO::poll_wait, IO::AIO::poll_cb
576 while IO::AIO::nreqs; 909 while IO::AIO::nreqs;
577 910
911=item IO::AIO::nready
912
913Returns the number of requests currently in the ready state (not yet
914executed).
915
916=item IO::AIO::npending
917
918Returns the number of requests currently in the pending state (executed,
919but not yet processed by poll_cb).
920
578=item IO::AIO::flush 921=item IO::AIO::flush
579 922
580Wait till all outstanding AIO requests have been handled. 923Wait till all outstanding AIO requests have been handled.
581 924
582Strictly equivalent to: 925Strictly equivalent to:
593 IO::AIO::poll_wait, IO::AIO::poll_cb 936 IO::AIO::poll_wait, IO::AIO::poll_cb
594 if IO::AIO::nreqs; 937 if IO::AIO::nreqs;
595 938
596=item IO::AIO::min_parallel $nthreads 939=item IO::AIO::min_parallel $nthreads
597 940
598Set the minimum number of AIO threads to C<$nthreads>. The current default 941Set the minimum number of AIO threads to C<$nthreads>. The current
599is C<4>, which means four asynchronous operations can be done at one time 942default is C<8>, which means eight asynchronous operations can execute
600(the number of outstanding operations, however, is unlimited). 943concurrently at any one time (the number of outstanding requests,
944however, is unlimited).
601 945
602IO::AIO starts threads only on demand, when an AIO request is queued and 946IO::AIO starts threads only on demand, when an AIO request is queued and
603no free thread exists. 947no free thread exists.
604 948
605It is recommended to keep the number of threads low, as some Linux 949It is recommended to keep the number of threads relatively low, as some
606kernel versions will scale negatively with the number of threads (higher 950Linux kernel versions will scale negatively with the number of threads
607parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 951(higher parallelity => MUCH higher latency). With current Linux 2.6
608threads should be fine. 952versions, 4-32 threads should be fine.
609 953
610Under most circumstances you don't need to call this function, as the 954Under most circumstances you don't need to call this function, as the
611module selects a default that is suitable for low to moderate load. 955module selects a default that is suitable for low to moderate load.
612 956
613=item IO::AIO::max_parallel $nthreads 957=item IO::AIO::max_parallel $nthreads
622This module automatically runs C<max_parallel 0> at program end, to ensure 966This module automatically runs C<max_parallel 0> at program end, to ensure
623that all threads are killed and that there are no outstanding requests. 967that all threads are killed and that there are no outstanding requests.
624 968
625Under normal circumstances you don't need to call this function. 969Under normal circumstances you don't need to call this function.
626 970
627=item $oldnreqs = IO::AIO::max_outstanding $nreqs 971=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
972
973This is a very bad function to use in interactive programs because it
974blocks, and a bad way to reduce concurrency because it is inexact: Better
975use an C<aio_group> together with a feed callback.
628 976
629Sets the maximum number of outstanding requests to C<$nreqs>. If you 977Sets the maximum number of outstanding requests to C<$nreqs>. If you
630try to queue up more than this number of requests, the caller will block until 978to queue up more than this number of requests, the next call to the
631some requests have been handled. 979C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
980function will block until the limit is no longer exceeded.
632 981
633The default is very large, so normally there is no practical limit. If you 982The default value is very large, so there is no practical limit on the
634queue up many requests in a loop it often improves speed if you set 983number of outstanding requests.
635this to a relatively low number, such as C<100>.
636 984
637Under normal circumstances you don't need to call this function. 985You can still queue as many requests as you want. Therefore,
986C<max_oustsanding> is mainly useful in simple scripts (with low values) or
987as a stop gap to shield against fatal memory overflow (with large values).
638 988
639=back 989=back
640 990
641=cut 991=cut
642 992
654 or return undef; 1004 or return undef;
655 1005
656 *$sym 1006 *$sym
657} 1007}
658 1008
659min_parallel 4; 1009min_parallel 8;
660 1010
661END { 1011END {
662 max_parallel 0; 1012 min_parallel 1;
663} 1013 flush;
1014};
664 1015
6651; 10161;
666 1017
667=head2 FORK BEHAVIOUR 1018=head2 FORK BEHAVIOUR
668 1019
669This module should do "the right thing" when the process using it forks: 1020This module should do "the right thing" when the process using it forks:
670 1021
671Before the fork, IO::AIO enters a quiescent state where no requests 1022Before the fork, IO::AIO enters a quiescent state where no requests
672can be added in other threads and no results will be processed. After 1023can be added in other threads and no results will be processed. After
673the fork the parent simply leaves the quiescent state and continues 1024the fork the parent simply leaves the quiescent state and continues
674request/result processing, while the child clears the request/result 1025request/result processing, while the child frees the request/result queue
675queue (so the requests started before the fork will only be handled in 1026(so that the requests started before the fork will only be handled in the
676the parent). Threads will be started on demand until the limit ste in the 1027parent). Threads will be started on demand until the limit set in the
677parent process has been reached again. 1028parent process has been reached again.
678 1029
679In short: the parent will, after a short pause, continue as if fork had 1030In short: the parent will, after a short pause, continue as if fork had
680not been called, while the child will act as if IO::AIO has not been used 1031not been called, while the child will act as if IO::AIO has not been used
681yet. 1032yet.
682 1033
1034=head2 MEMORY USAGE
1035
1036Per-request usage:
1037
1038Each aio request uses - depending on your architecture - around 100-200
1039bytes of memory. In addition, stat requests need a stat buffer (possibly
1040a few hundred bytes), readdir requires a result buffer and so on. Perl
1041scalars and other data passed into aio requests will also be locked and
1042will consume memory till the request has entered the done state.
1043
1044This is now awfully much, so queuing lots of requests is not usually a
1045problem.
1046
1047Per-thread usage:
1048
1049In the execution phase, some aio requests require more memory for
1050temporary buffers, and each thread requires a stack and other data
1051structures (usually around 16k-128k, depending on the OS).
1052
1053=head1 KNOWN BUGS
1054
1055Known bugs will be fixed in the next release.
1056
683=head1 SEE ALSO 1057=head1 SEE ALSO
684 1058
685L<Coro>, L<Linux::AIO> (obsolete). 1059L<Coro::AIO>.
686 1060
687=head1 AUTHOR 1061=head1 AUTHOR
688 1062
689 Marc Lehmann <schmorp@schmorp.de> 1063 Marc Lehmann <schmorp@schmorp.de>
690 http://home.schmorp.de/ 1064 http://home.schmorp.de/

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines