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Revision 1.136 by root, Tue Sep 30 14:07:59 2008 UTC vs.
Revision 1.197 by root, Wed Jun 29 10:49:35 2011 UTC

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4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
9 aio_open "/etc/passwd", O_RDONLY, 0, sub { 9 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10 my $fh = shift 10 my $fh = shift
11 or die "/etc/passwd: $!"; 11 or die "/etc/passwd: $!";
12 ... 12 ...
13 }; 13 };
14 14
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26 $req->cancel; # cancel request if still in queue 26 $req->cancel; # cancel request if still in queue
27 27
28 my $grp = aio_group sub { print "all stats done\n" }; 28 my $grp = aio_group sub { print "all stats done\n" };
29 add $grp aio_stat "..." for ...; 29 add $grp aio_stat "..." for ...;
30 30
31 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32 use AnyEvent::AIO;
33
34 # EV integration
35 my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37 # Event integration
38 Event->io (fd => IO::AIO::poll_fileno,
39 poll => 'r',
40 cb => \&IO::AIO::poll_cb);
41
42 # Glib/Gtk2 integration
43 add_watch Glib::IO IO::AIO::poll_fileno,
44 in => sub { IO::AIO::poll_cb; 1 };
45
46 # Tk integration
47 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48 readable => \&IO::AIO::poll_cb);
49
50 # Danga::Socket integration
51 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52 \&IO::AIO::poll_cb);
53
54=head1 DESCRIPTION 31=head1 DESCRIPTION
55 32
56This module implements asynchronous I/O using whatever means your 33This module implements asynchronous I/O using whatever means your
57operating system supports. 34operating system supports. It is implemented as an interface to C<libeio>
35(L<http://software.schmorp.de/pkg/libeio.html>).
58 36
59Asynchronous means that operations that can normally block your program 37Asynchronous means that operations that can normally block your program
60(e.g. reading from disk) will be done asynchronously: the operation 38(e.g. reading from disk) will be done asynchronously: the operation
61will still block, but you can do something else in the meantime. This 39will still block, but you can do something else in the meantime. This
62is extremely useful for programs that need to stay interactive even 40is extremely useful for programs that need to stay interactive even
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66on a RAID volume or over NFS when you do a number of stat operations 44on a RAID volume or over NFS when you do a number of stat operations
67concurrently. 45concurrently.
68 46
69While most of this works on all types of file descriptors (for 47While most of this works on all types of file descriptors (for
70example sockets), using these functions on file descriptors that 48example sockets), using these functions on file descriptors that
71support nonblocking operation (again, sockets, pipes etc.) is very 49support nonblocking operation (again, sockets, pipes etc.) is
72inefficient. Use an event loop for that (such as the L<Event|Event> 50very inefficient. Use an event loop for that (such as the L<EV>
73module): IO::AIO will naturally fit into such an event loop itself. 51module): IO::AIO will naturally fit into such an event loop itself.
74 52
75In this version, a number of threads are started that execute your 53In this version, a number of threads are started that execute your
76requests and signal their completion. You don't need thread support 54requests and signal their completion. You don't need thread support
77in perl, and the threads created by this module will not be visible 55in perl, and the threads created by this module will not be visible
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87yourself, always call C<poll_cb> from within the same thread, or never 65yourself, always call C<poll_cb> from within the same thread, or never
88call C<poll_cb> (or other C<aio_> functions) recursively. 66call C<poll_cb> (or other C<aio_> functions) recursively.
89 67
90=head2 EXAMPLE 68=head2 EXAMPLE
91 69
92This is a simple example that uses the Event module and loads 70This is a simple example that uses the EV module and loads
93F</etc/passwd> asynchronously: 71F</etc/passwd> asynchronously:
94 72
95 use Fcntl; 73 use Fcntl;
96 use Event; 74 use EV;
97 use IO::AIO; 75 use IO::AIO;
98 76
99 # register the IO::AIO callback with Event 77 # register the IO::AIO callback with EV
100 Event->io (fd => IO::AIO::poll_fileno, 78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
101 poll => 'r',
102 cb => \&IO::AIO::poll_cb);
103 79
104 # queue the request to open /etc/passwd 80 # queue the request to open /etc/passwd
105 aio_open "/etc/passwd", O_RDONLY, 0, sub { 81 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106 my $fh = shift 82 my $fh = shift
107 or die "error while opening: $!"; 83 or die "error while opening: $!";
108 84
109 # stat'ing filehandles is generally non-blocking 85 # stat'ing filehandles is generally non-blocking
110 my $size = -s $fh; 86 my $size = -s $fh;
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119 95
120 # file contents now in $contents 96 # file contents now in $contents
121 print $contents; 97 print $contents;
122 98
123 # exit event loop and program 99 # exit event loop and program
124 Event::unloop; 100 EV::unloop;
125 }; 101 };
126 }; 102 };
127 103
128 # possibly queue up other requests, or open GUI windows, 104 # possibly queue up other requests, or open GUI windows,
129 # check for sockets etc. etc. 105 # check for sockets etc. etc.
130 106
131 # process events as long as there are some: 107 # process events as long as there are some:
132 Event::loop; 108 EV::loop;
133 109
134=head1 REQUEST ANATOMY AND LIFETIME 110=head1 REQUEST ANATOMY AND LIFETIME
135 111
136Every C<aio_*> function creates a request. which is a C data structure not 112Every C<aio_*> function creates a request. which is a C data structure not
137directly visible to Perl. 113directly visible to Perl.
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187 163
188package IO::AIO; 164package IO::AIO;
189 165
190use Carp (); 166use Carp ();
191 167
192no warnings; 168use common::sense;
193use strict 'vars';
194 169
195use base 'Exporter'; 170use base 'Exporter';
196 171
197BEGIN { 172BEGIN {
198 our $VERSION = '3.1'; 173 our $VERSION = '3.9';
199 174
200 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 175 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
201 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir 176 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync 177 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
203 aio_fdatasync aio_pathsync aio_readahead 178 aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
204 aio_rename aio_link aio_move aio_copy aio_group 179 aio_rename aio_link aio_move aio_copy aio_group
205 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 180 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206 aio_chmod aio_utime aio_truncate); 181 aio_chmod aio_utime aio_truncate
182 aio_msync aio_mtouch aio_mlock aio_mlockall
183 aio_statvfs);
207 184
208 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 185 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 186 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210 min_parallel max_parallel max_idle 187 min_parallel max_parallel max_idle idle_timeout
211 nreqs nready npending nthreads 188 nreqs nready npending nthreads
212 max_poll_time max_poll_reqs); 189 max_poll_time max_poll_reqs
190 sendfile fadvise madvise
191 mmap munmap munlock munlockall);
192
193 push @AIO_REQ, qw(aio_busy); # not exported
213 194
214 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 195 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
215 196
216 require XSLoader; 197 require XSLoader;
217 XSLoader::load ("IO::AIO", $VERSION); 198 XSLoader::load ("IO::AIO", $VERSION);
218} 199}
219 200
220=head1 FUNCTIONS 201=head1 FUNCTIONS
202
203=head2 QUICK OVERVIEW
204
205This section simply lists the prototypes of the most important functions
206for quick reference. See the following sections for function-by-function
207documentation.
208
209 aio_open $pathname, $flags, $mode, $callback->($fh)
210 aio_close $fh, $callback->($status)
211 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214 aio_readahead $fh,$offset,$length, $callback->($retval)
215 aio_stat $fh_or_path, $callback->($status)
216 aio_lstat $fh, $callback->($status)
217 aio_statvfs $fh_or_path, $callback->($statvfs)
218 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
220 aio_truncate $fh_or_path, $offset, $callback->($status)
221 aio_chmod $fh_or_path, $mode, $callback->($status)
222 aio_unlink $pathname, $callback->($status)
223 aio_mknod $path, $mode, $dev, $callback->($status)
224 aio_link $srcpath, $dstpath, $callback->($status)
225 aio_symlink $srcpath, $dstpath, $callback->($status)
226 aio_readlink $path, $callback->($link)
227 aio_rename $srcpath, $dstpath, $callback->($status)
228 aio_mkdir $pathname, $mode, $callback->($status)
229 aio_rmdir $pathname, $callback->($status)
230 aio_readdir $pathname, $callback->($entries)
231 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
234 aio_load $path, $data, $callback->($status)
235 aio_copy $srcpath, $dstpath, $callback->($status)
236 aio_move $srcpath, $dstpath, $callback->($status)
237 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238 aio_rmtree $path, $callback->($status)
239 aio_sync $callback->($status)
240 aio_fsync $fh, $callback->($status)
241 aio_fdatasync $fh, $callback->($status)
242 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243 aio_pathsync $path, $callback->($status)
244 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
245 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247 aio_mlockall $flags, $callback->($status)
248 aio_group $callback->(...)
249 aio_nop $callback->()
250
251 $prev_pri = aioreq_pri [$pri]
252 aioreq_nice $pri_adjust
253
254 IO::AIO::poll_wait
255 IO::AIO::poll_cb
256 IO::AIO::poll
257 IO::AIO::flush
258 IO::AIO::max_poll_reqs $nreqs
259 IO::AIO::max_poll_time $seconds
260 IO::AIO::min_parallel $nthreads
261 IO::AIO::max_parallel $nthreads
262 IO::AIO::max_idle $nthreads
263 IO::AIO::idle_timeout $seconds
264 IO::AIO::max_outstanding $maxreqs
265 IO::AIO::nreqs
266 IO::AIO::nready
267 IO::AIO::npending
268
269 IO::AIO::sendfile $ofh, $ifh, $offset, $count
270 IO::AIO::fadvise $fh, $offset, $len, $advice
271 IO::AIO::madvise $scalar, $offset, $length, $advice
272 IO::AIO::mprotect $scalar, $offset, $length, $protect
273 IO::AIO::munlock $scalar, $offset = 0, $length = undef
274 IO::AIO::munlockall
221 275
222=head2 AIO REQUEST FUNCTIONS 276=head2 AIO REQUEST FUNCTIONS
223 277
224All the C<aio_*> calls are more or less thin wrappers around the syscall 278All the C<aio_*> calls are more or less thin wrappers around the syscall
225with the same name (sans C<aio_>). The arguments are similar or identical, 279with the same name (sans C<aio_>). The arguments are similar or identical,
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305by the umask in effect then the request is being executed, so better never 359by the umask in effect then the request is being executed, so better never
306change the umask. 360change the umask.
307 361
308Example: 362Example:
309 363
310 aio_open "/etc/passwd", O_RDONLY, 0, sub { 364 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
311 if ($_[0]) { 365 if ($_[0]) {
312 print "open successful, fh is $_[0]\n"; 366 print "open successful, fh is $_[0]\n";
313 ... 367 ...
314 } else { 368 } else {
315 die "open failed: $!\n"; 369 die "open failed: $!\n";
316 } 370 }
317 }; 371 };
318 372
373In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
374C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
375following POSIX and non-POSIX constants are available (missing ones on
376your system are, as usual, C<0>):
377
378C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
379C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
380C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
381
319 382
320=item aio_close $fh, $callback->($status) 383=item aio_close $fh, $callback->($status)
321 384
322Asynchronously close a file and call the callback with the result 385Asynchronously close a file and call the callback with the result
323code. 386code.
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336 399
337=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 400=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
338 401
339=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 402=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340 403
341Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset> 404Reads or writes C<$length> bytes from or to the specified C<$fh> and
342into the scalar given by C<$data> and offset C<$dataoffset> and calls the 405C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
343callback without the actual number of bytes read (or -1 on error, just 406and calls the callback without the actual number of bytes read (or -1 on
344like the syscall). 407error, just like the syscall).
408
409C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
410offset plus the actual number of bytes read.
345 411
346If C<$offset> is undefined, then the current file descriptor offset will 412If C<$offset> is undefined, then the current file descriptor offset will
347be used (and updated), otherwise the file descriptor offset will not be 413be used (and updated), otherwise the file descriptor offset will not be
348changed by these calls. 414changed by these calls.
349 415
350If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>. 416If C<$length> is undefined in C<aio_write>, use the remaining length of
417C<$data>.
351 418
352If C<$dataoffset> is less than zero, it will be counted from the end of 419If C<$dataoffset> is less than zero, it will be counted from the end of
353C<$data>. 420C<$data>.
354 421
355The C<$data> scalar I<MUST NOT> be modified in any way while the request 422The C<$data> scalar I<MUST NOT> be modified in any way while the request
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369 436
370Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 437Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
371reading at byte offset C<$in_offset>, and starts writing at the current 438reading at byte offset C<$in_offset>, and starts writing at the current
372file offset of C<$out_fh>. Because of that, it is not safe to issue more 439file offset of C<$out_fh>. Because of that, it is not safe to issue more
373than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 440than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
374other. 441other. The same C<$in_fh> works fine though, as this function does not
442move or use the file offset of C<$in_fh>.
375 443
444Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
445are written, and there is no way to find out how many more bytes have been
446read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
447number of bytes written to C<$out_fh>. Only if the result value equals
448C<$length> one can assume that C<$length> bytes have been read.
449
450Unlike with other C<aio_> functions, it makes a lot of sense to use
451C<aio_sendfile> on non-blocking sockets, as long as one end (typically
452the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
453the socket I/O will be non-blocking. Note, however, that you can run
454into a trap where C<aio_sendfile> reads some data with readahead, then
455fails to write all data, and when the socket is ready the next time, the
456data in the cache is already lost, forcing C<aio_sendfile> to again hit
457the disk. Explicit C<aio_read> + C<aio_write> let's you better control
458resource usage.
459
376This call tries to make use of a native C<sendfile> syscall to provide 460This call tries to make use of a native C<sendfile>-like syscall to
377zero-copy operation. For this to work, C<$out_fh> should refer to a 461provide zero-copy operation. For this to work, C<$out_fh> should refer to
378socket, and C<$in_fh> should refer to mmap'able file. 462a socket, and C<$in_fh> should refer to an mmap'able file.
379 463
380If the native sendfile call fails or is not implemented, it will be 464If a native sendfile cannot be found or it fails with C<ENOSYS>,
381emulated, so you can call C<aio_sendfile> on any type of filehandle 465C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
466C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
382regardless of the limitations of the operating system. 467type of filehandle regardless of the limitations of the operating system.
383 468
384Please note, however, that C<aio_sendfile> can read more bytes from 469As native sendfile syscalls (as practically any non-POSIX interface hacked
385C<$in_fh> than are written, and there is no way to find out how many 470together in a hurry to improve benchmark numbers) tend to be rather buggy
386bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 471on many systems, this implementation tries to work around some known bugs
387provides the number of bytes written to C<$out_fh>. Only if the result 472in Linux and FreeBSD kernels (probably others, too), but that might fail,
388value equals C<$length> one can assume that C<$length> bytes have been 473so you really really should check the return value of C<aio_sendfile> -
389read. 474fewre bytes than expected might have been transferred.
390 475
391 476
392=item aio_readahead $fh,$offset,$length, $callback->($retval) 477=item aio_readahead $fh,$offset,$length, $callback->($retval)
393 478
394C<aio_readahead> populates the page cache with data from a file so that 479C<aio_readahead> populates the page cache with data from a file so that
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417 502
418Currently, the stats are always 64-bit-stats, i.e. instead of returning an 503Currently, the stats are always 64-bit-stats, i.e. instead of returning an
419error when stat'ing a large file, the results will be silently truncated 504error when stat'ing a large file, the results will be silently truncated
420unless perl itself is compiled with large file support. 505unless perl itself is compiled with large file support.
421 506
507To help interpret the mode and dev/rdev stat values, IO::AIO offers the
508following constants and functions (if not implemented, the constants will
509be C<0> and the functions will either C<croak> or fall back on traditional
510behaviour).
511
512C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
513C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
514C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
515
422Example: Print the length of F</etc/passwd>: 516Example: Print the length of F</etc/passwd>:
423 517
424 aio_stat "/etc/passwd", sub { 518 aio_stat "/etc/passwd", sub {
425 $_[0] and die "stat failed: $!"; 519 $_[0] and die "stat failed: $!";
426 print "size is ", -s _, "\n"; 520 print "size is ", -s _, "\n";
427 }; 521 };
428 522
429 523
524=item aio_statvfs $fh_or_path, $callback->($statvfs)
525
526Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
527whether a file handle or path was passed.
528
529On success, the callback is passed a hash reference with the following
530members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
531C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
532is passed.
533
534The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
535C<ST_NOSUID>.
536
537The following non-POSIX IO::AIO::ST_* flag masks are defined to
538their correct value when available, or to C<0> on systems that do
539not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
540C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
541C<ST_NODIRATIME> and C<ST_RELATIME>.
542
543Example: stat C</wd> and dump out the data if successful.
544
545 aio_statvfs "/wd", sub {
546 my $f = $_[0]
547 or die "statvfs: $!";
548
549 use Data::Dumper;
550 say Dumper $f;
551 };
552
553 # result:
554 {
555 bsize => 1024,
556 bfree => 4333064312,
557 blocks => 10253828096,
558 files => 2050765568,
559 flag => 4096,
560 favail => 2042092649,
561 bavail => 4333064312,
562 ffree => 2042092649,
563 namemax => 255,
564 frsize => 1024,
565 fsid => 1810
566 }
567
568
430=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 569=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
431 570
432Works like perl's C<utime> function (including the special case of $atime 571Works like perl's C<utime> function (including the special case of $atime
433and $mtime being undef). Fractional times are supported if the underlying 572and $mtime being undef). Fractional times are supported if the underlying
434syscalls support them. 573syscalls support them.
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482 621
483The only (POSIX-) portable way of calling this function is: 622The only (POSIX-) portable way of calling this function is:
484 623
485 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 624 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
486 625
626See C<aio_stat> for info about some potentially helpful extra constants
627and functions.
487 628
488=item aio_link $srcpath, $dstpath, $callback->($status) 629=item aio_link $srcpath, $dstpath, $callback->($status)
489 630
490Asynchronously create a new link to the existing object at C<$srcpath> at 631Asynchronously create a new link to the existing object at C<$srcpath> at
491the path C<$dstpath> and call the callback with the result code. 632the path C<$dstpath> and call the callback with the result code.
… …
527 668
528Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 669Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
529directory (i.e. opendir + readdir + closedir). The entries will not be 670directory (i.e. opendir + readdir + closedir). The entries will not be
530sorted, and will B<NOT> include the C<.> and C<..> entries. 671sorted, and will B<NOT> include the C<.> and C<..> entries.
531 672
532The callback a single argument which is either C<undef> or an array-ref 673The callback is passed a single argument which is either C<undef> or an
533with the filenames. 674array-ref with the filenames.
675
676
677=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
678
679Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
680behaviour and output format. In case of an error, C<$entries> will be
681C<undef>.
682
683The flags are a combination of the following constants, ORed together (the
684flags will also be passed to the callback, possibly modified):
685
686=over 4
687
688=item IO::AIO::READDIR_DENTS
689
690When this flag is off, then the callback gets an arrayref consisting of
691names only (as with C<aio_readdir>), otherwise it gets an arrayref with
692C<[$name, $type, $inode]> arrayrefs, each describing a single directory
693entry in more detail.
694
695C<$name> is the name of the entry.
696
697C<$type> is one of the C<IO::AIO::DT_xxx> constants:
698
699C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
700C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
701C<IO::AIO::DT_WHT>.
702
703C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
704know, you have to run stat yourself. Also, for speed reasons, the C<$type>
705scalars are read-only: you can not modify them.
706
707C<$inode> is the inode number (which might not be exact on systems with 64
708bit inode numbers and 32 bit perls). This field has unspecified content on
709systems that do not deliver the inode information.
710
711=item IO::AIO::READDIR_DIRS_FIRST
712
713When this flag is set, then the names will be returned in an order where
714likely directories come first, in optimal stat order. This is useful when
715you need to quickly find directories, or you want to find all directories
716while avoiding to stat() each entry.
717
718If the system returns type information in readdir, then this is used
719to find directories directly. Otherwise, likely directories are names
720beginning with ".", or otherwise names with no dots, of which names with
721short names are tried first.
722
723=item IO::AIO::READDIR_STAT_ORDER
724
725When this flag is set, then the names will be returned in an order
726suitable for stat()'ing each one. That is, when you plan to stat()
727all files in the given directory, then the returned order will likely
728be fastest.
729
730If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
731the likely dirs come first, resulting in a less optimal stat order.
732
733=item IO::AIO::READDIR_FOUND_UNKNOWN
734
735This flag should not be set when calling C<aio_readdirx>. Instead, it
736is being set by C<aio_readdirx>, when any of the C<$type>'s found were
737C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
738C<$type>'s are known, which can be used to speed up some algorithms.
739
740=back
534 741
535 742
536=item aio_load $path, $data, $callback->($status) 743=item aio_load $path, $data, $callback->($status)
537 744
538This is a composite request that tries to fully load the given file into 745This is a composite request that tries to fully load the given file into
… …
563 770
564=item aio_copy $srcpath, $dstpath, $callback->($status) 771=item aio_copy $srcpath, $dstpath, $callback->($status)
565 772
566Try to copy the I<file> (directories not supported as either source or 773Try to copy the I<file> (directories not supported as either source or
567destination) from C<$srcpath> to C<$dstpath> and call the callback with 774destination) from C<$srcpath> to C<$dstpath> and call the callback with
568the C<0> (error) or C<-1> ok. 775a status of C<0> (ok) or C<-1> (error, see C<$!>).
569 776
570This is a composite request that creates the destination file with 777This is a composite request that creates the destination file with
571mode 0200 and copies the contents of the source file into it using 778mode 0200 and copies the contents of the source file into it using
572C<aio_sendfile>, followed by restoring atime, mtime, access mode and 779C<aio_sendfile>, followed by restoring atime, mtime, access mode and
573uid/gid, in that order. 780uid/gid, in that order.
… …
585 my $grp = aio_group $cb; 792 my $grp = aio_group $cb;
586 793
587 aioreq_pri $pri; 794 aioreq_pri $pri;
588 add $grp aio_open $src, O_RDONLY, 0, sub { 795 add $grp aio_open $src, O_RDONLY, 0, sub {
589 if (my $src_fh = $_[0]) { 796 if (my $src_fh = $_[0]) {
590 my @stat = stat $src_fh; 797 my @stat = stat $src_fh; # hmm, might block over nfs?
591 798
592 aioreq_pri $pri; 799 aioreq_pri $pri;
593 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { 800 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
594 if (my $dst_fh = $_[0]) { 801 if (my $dst_fh = $_[0]) {
595 aioreq_pri $pri; 802 aioreq_pri $pri;
596 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { 803 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
597 if ($_[0] == $stat[7]) { 804 if ($_[0] == $stat[7]) {
598 $grp->result (0); 805 $grp->result (0);
599 close $src_fh; 806 close $src_fh;
600 807
601 # those should not normally block. should. should. 808 my $ch = sub {
602 utime $stat[8], $stat[9], $dst; 809 aioreq_pri $pri;
603 chmod $stat[2] & 07777, $dst_fh; 810 add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
604 chown $stat[4], $stat[5], $dst_fh; 811 aioreq_pri $pri;
812 add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
813 aioreq_pri $pri;
814 add $grp aio_close $dst_fh;
815 }
816 };
817 };
605 818
606 aioreq_pri $pri; 819 aioreq_pri $pri;
607 add $grp aio_close $dst_fh; 820 add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
821 if ($_[0] < 0 && $! == ENOSYS) {
822 aioreq_pri $pri;
823 add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
824 } else {
825 $ch->();
826 }
827 };
608 } else { 828 } else {
609 $grp->result (-1); 829 $grp->result (-1);
610 close $src_fh; 830 close $src_fh;
611 close $dst_fh; 831 close $dst_fh;
612 832
… …
629 849
630=item aio_move $srcpath, $dstpath, $callback->($status) 850=item aio_move $srcpath, $dstpath, $callback->($status)
631 851
632Try to move the I<file> (directories not supported as either source or 852Try to move the I<file> (directories not supported as either source or
633destination) from C<$srcpath> to C<$dstpath> and call the callback with 853destination) from C<$srcpath> to C<$dstpath> and call the callback with
634the C<0> (error) or C<-1> ok. 854a status of C<0> (ok) or C<-1> (error, see C<$!>).
635 855
636This is a composite request that tries to rename(2) the file first. If 856This is a composite request that tries to rename(2) the file first; if
637rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if 857rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
638that is successful, unlinking the C<$srcpath>. 858that is successful, unlinks the C<$srcpath>.
639 859
640=cut 860=cut
641 861
642sub aio_move($$;$) { 862sub aio_move($$;$) {
643 my ($src, $dst, $cb) = @_; 863 my ($src, $dst, $cb) = @_;
… …
650 if ($_[0] && $! == EXDEV) { 870 if ($_[0] && $! == EXDEV) {
651 aioreq_pri $pri; 871 aioreq_pri $pri;
652 add $grp aio_copy $src, $dst, sub { 872 add $grp aio_copy $src, $dst, sub {
653 $grp->result ($_[0]); 873 $grp->result ($_[0]);
654 874
655 if (!$_[0]) { 875 unless ($_[0]) {
656 aioreq_pri $pri; 876 aioreq_pri $pri;
657 add $grp aio_unlink $src; 877 add $grp aio_unlink $src;
658 } 878 }
659 }; 879 };
660 } else { 880 } else {
… …
690 910
691Implementation notes. 911Implementation notes.
692 912
693The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. 913The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
694 914
915If readdir returns file type information, then this is used directly to
916find directories.
917
695After reading the directory, the modification time, size etc. of the 918Otherwise, after reading the directory, the modification time, size etc.
696directory before and after the readdir is checked, and if they match (and 919of the directory before and after the readdir is checked, and if they
697isn't the current time), the link count will be used to decide how many 920match (and isn't the current time), the link count will be used to decide
698entries are directories (if >= 2). Otherwise, no knowledge of the number 921how many entries are directories (if >= 2). Otherwise, no knowledge of the
699of subdirectories will be assumed. 922number of subdirectories will be assumed.
700 923
701Then entries will be sorted into likely directories (everything without 924Then entries will be sorted into likely directories a non-initial dot
702a non-initial dot currently) and likely non-directories (everything 925currently) and likely non-directories (see C<aio_readdirx>). Then every
703else). Then every entry plus an appended C</.> will be C<stat>'ed, 926entry plus an appended C</.> will be C<stat>'ed, likely directories first,
704likely directories first. If that succeeds, it assumes that the entry 927in order of their inode numbers. If that succeeds, it assumes that the
705is a directory or a symlink to directory (which will be checked 928entry is a directory or a symlink to directory (which will be checked
706seperately). This is often faster than stat'ing the entry itself because 929seperately). This is often faster than stat'ing the entry itself because
707filesystems might detect the type of the entry without reading the inode 930filesystems might detect the type of the entry without reading the inode
708data (e.g. ext2fs filetype feature). 931data (e.g. ext2fs filetype feature), even on systems that cannot return
932the filetype information on readdir.
709 933
710If the known number of directories (link count - 2) has been reached, the 934If the known number of directories (link count - 2) has been reached, the
711rest of the entries is assumed to be non-directories. 935rest of the entries is assumed to be non-directories.
712 936
713This only works with certainty on POSIX (= UNIX) filesystems, which 937This only works with certainty on POSIX (= UNIX) filesystems, which
… …
735 my $now = time; 959 my $now = time;
736 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 960 my $hash1 = join ":", (stat _)[0,1,3,7,9];
737 961
738 # read the directory entries 962 # read the directory entries
739 aioreq_pri $pri; 963 aioreq_pri $pri;
740 add $grp aio_readdir $path, sub { 964 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
741 my $entries = shift 965 my $entries = shift
742 or return $grp->result (); 966 or return $grp->result ();
743 967
744 # stat the dir another time 968 # stat the dir another time
745 aioreq_pri $pri; 969 aioreq_pri $pri;
… …
751 # take the slow route if anything looks fishy 975 # take the slow route if anything looks fishy
752 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 976 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
753 $ndirs = -1; 977 $ndirs = -1;
754 } else { 978 } else {
755 # if nlink == 2, we are finished 979 # if nlink == 2, we are finished
756 # on non-posix-fs's, we rely on nlink < 2 980 # for non-posix-fs's, we rely on nlink < 2
757 $ndirs = (stat _)[3] - 2 981 $ndirs = (stat _)[3] - 2
758 or return $grp->result ([], $entries); 982 or return $grp->result ([], $entries);
759 } 983 }
760 984
761 # sort into likely dirs and likely nondirs
762 # dirs == files without ".", short entries first
763 $entries = [map $_->[0],
764 sort { $b->[1] cmp $a->[1] }
765 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
766 @$entries];
767
768 my (@dirs, @nondirs); 985 my (@dirs, @nondirs);
769 986
770 my $statgrp = add $grp aio_group sub { 987 my $statgrp = add $grp aio_group sub {
771 $grp->result (\@dirs, \@nondirs); 988 $grp->result (\@dirs, \@nondirs);
772 }; 989 };
773 990
774 limit $statgrp $maxreq; 991 limit $statgrp $maxreq;
775 feed $statgrp sub { 992 feed $statgrp sub {
776 return unless @$entries; 993 return unless @$entries;
777 my $entry = pop @$entries; 994 my $entry = shift @$entries;
778 995
779 aioreq_pri $pri; 996 aioreq_pri $pri;
780 add $statgrp aio_stat "$path/$entry/.", sub { 997 add $statgrp aio_stat "$path/$entry/.", sub {
781 if ($_[0] < 0) { 998 if ($_[0] < 0) {
782 push @nondirs, $entry; 999 push @nondirs, $entry;
… …
855callback with the fdatasync result code. 1072callback with the fdatasync result code.
856 1073
857If this call isn't available because your OS lacks it or it couldn't be 1074If this call isn't available because your OS lacks it or it couldn't be
858detected, it will be emulated by calling C<fsync> instead. 1075detected, it will be emulated by calling C<fsync> instead.
859 1076
1077=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1078
1079Sync the data portion of the file specified by C<$offset> and C<$length>
1080to disk (but NOT the metadata), by calling the Linux-specific
1081sync_file_range call. If sync_file_range is not available or it returns
1082ENOSYS, then fdatasync or fsync is being substituted.
1083
1084C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1085C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1086C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1087manpage for details.
1088
860=item aio_pathsync $path, $callback->($status) 1089=item aio_pathsync $path, $callback->($status)
861 1090
862This request tries to open, fsync and close the given path. This is a 1091This request tries to open, fsync and close the given path. This is a
863composite request intended to sync directories after directory operations 1092composite request intended to sync directories after directory operations
864(E.g. rename). This might not work on all operating systems or have any 1093(E.g. rename). This might not work on all operating systems or have any
865specific effect, but usually it makes sure that directory changes get 1094specific effect, but usually it makes sure that directory changes get
866written to disc. It works for anything that can be opened for read-only, 1095written to disc. It works for anything that can be opened for read-only,
867not just directories. 1096not just directories.
1097
1098Future versions of this function might fall back to other methods when
1099C<fsync> on the directory fails (such as calling C<sync>).
868 1100
869Passes C<0> when everything went ok, and C<-1> on error. 1101Passes C<0> when everything went ok, and C<-1> on error.
870 1102
871=cut 1103=cut
872 1104
… …
893 }; 1125 };
894 1126
895 $grp 1127 $grp
896} 1128}
897 1129
1130=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1131
1132This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1133scalars (see the C<IO::AIO::mmap> function, although it also works on data
1134scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1135scalar must only be modified in-place while an aio operation is pending on
1136it).
1137
1138It calls the C<msync> function of your OS, if available, with the memory
1139area starting at C<$offset> in the string and ending C<$length> bytes
1140later. If C<$length> is negative, counts from the end, and if C<$length>
1141is C<undef>, then it goes till the end of the string. The flags can be
1142a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
1143C<IO::AIO::MS_SYNC>.
1144
1145=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1146
1147This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1148scalars.
1149
1150It touches (reads or writes) all memory pages in the specified
1151range inside the scalar. All caveats and parameters are the same
1152as for C<aio_msync>, above, except for flags, which must be either
1153C<0> (which reads all pages and ensures they are instantiated) or
1154C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
1155writing an octet from it, which dirties the page).
1156
1157=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1158
1159This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1160scalars.
1161
1162It reads in all the pages of the underlying storage into memory (if any)
1163and locks them, so they are not getting swapped/paged out or removed.
1164
1165If C<$length> is undefined, then the scalar will be locked till the end.
1166
1167On systems that do not implement C<mlock>, this function returns C<-1>
1168and sets errno to C<ENOSYS>.
1169
1170Note that the corresponding C<munlock> is synchronous and is
1171documented under L<MISCELLANEOUS FUNCTIONS>.
1172
1173Example: open a file, mmap and mlock it - both will be undone when
1174C<$data> gets destroyed.
1175
1176 open my $fh, "<", $path or die "$path: $!";
1177 my $data;
1178 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1179 aio_mlock $data; # mlock in background
1180
1181=item aio_mlockall $flags, $callback->($status)
1182
1183Calls the C<mlockall> function with the given C<$flags> (a combination of
1184C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1185
1186On systems that do not implement C<mlockall>, this function returns C<-1>
1187and sets errno to C<ENOSYS>.
1188
1189Note that the corresponding C<munlockall> is synchronous and is
1190documented under L<MISCELLANEOUS FUNCTIONS>.
1191
1192Example: asynchronously lock all current and future pages into memory.
1193
1194 aio_mlockall IO::AIO::MCL_FUTURE;
1195
898=item aio_group $callback->(...) 1196=item aio_group $callback->(...)
899 1197
900This is a very special aio request: Instead of doing something, it is a 1198This is a very special aio request: Instead of doing something, it is a
901container for other aio requests, which is useful if you want to bundle 1199container for other aio requests, which is useful if you want to bundle
902many requests into a single, composite, request with a definite callback 1200many requests into a single, composite, request with a definite callback
… …
951=item cancel $req 1249=item cancel $req
952 1250
953Cancels the request, if possible. Has the effect of skipping execution 1251Cancels the request, if possible. Has the effect of skipping execution
954when entering the B<execute> state and skipping calling the callback when 1252when entering the B<execute> state and skipping calling the callback when
955entering the the B<result> state, but will leave the request otherwise 1253entering the the B<result> state, but will leave the request otherwise
956untouched. That means that requests that currently execute will not be 1254untouched (with the exception of readdir). That means that requests that
957stopped and resources held by the request will not be freed prematurely. 1255currently execute will not be stopped and resources held by the request
1256will not be freed prematurely.
958 1257
959=item cb $req $callback->(...) 1258=item cb $req $callback->(...)
960 1259
961Replace (or simply set) the callback registered to the request. 1260Replace (or simply set) the callback registered to the request.
962 1261
… …
1036=item $grp->cancel_subs 1335=item $grp->cancel_subs
1037 1336
1038Cancel all subrequests and clears any feeder, but not the group request 1337Cancel all subrequests and clears any feeder, but not the group request
1039itself. Useful when you queued a lot of events but got a result early. 1338itself. Useful when you queued a lot of events but got a result early.
1040 1339
1340The group request will finish normally (you cannot add requests to the
1341group).
1342
1041=item $grp->result (...) 1343=item $grp->result (...)
1042 1344
1043Set the result value(s) that will be passed to the group callback when all 1345Set the result value(s) that will be passed to the group callback when all
1044subrequests have finished and set the groups errno to the current value 1346subrequests have finished and set the groups errno to the current value
1045of errno (just like calling C<errno> without an error number). By default, 1347of errno (just like calling C<errno> without an error number). By default,
… …
1060=item feed $grp $callback->($grp) 1362=item feed $grp $callback->($grp)
1061 1363
1062Sets a feeder/generator on this group: every group can have an attached 1364Sets a feeder/generator on this group: every group can have an attached
1063generator that generates requests if idle. The idea behind this is that, 1365generator that generates requests if idle. The idea behind this is that,
1064although you could just queue as many requests as you want in a group, 1366although you could just queue as many requests as you want in a group,
1065this might starve other requests for a potentially long time. For 1367this might starve other requests for a potentially long time. For example,
1066example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> 1368C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
1067requests, delaying any later requests for a long time. 1369delaying any later requests for a long time.
1068 1370
1069To avoid this, and allow incremental generation of requests, you can 1371To avoid this, and allow incremental generation of requests, you can
1070instead a group and set a feeder on it that generates those requests. The 1372instead a group and set a feeder on it that generates those requests. The
1071feed callback will be called whenever there are few enough (see C<limit>, 1373feed callback will be called whenever there are few enough (see C<limit>,
1072below) requests active in the group itself and is expected to queue more 1374below) requests active in the group itself and is expected to queue more
… …
1076not impose any limits). 1378not impose any limits).
1077 1379
1078If the feed does not queue more requests when called, it will be 1380If the feed does not queue more requests when called, it will be
1079automatically removed from the group. 1381automatically removed from the group.
1080 1382
1081If the feed limit is C<0>, it will be set to C<2> automatically. 1383If the feed limit is C<0> when this method is called, it will be set to
1384C<2> automatically.
1082 1385
1083Example: 1386Example:
1084 1387
1085 # stat all files in @files, but only ever use four aio requests concurrently: 1388 # stat all files in @files, but only ever use four aio requests concurrently:
1086 1389
… …
1098Sets the feeder limit for the group: The feeder will be called whenever 1401Sets the feeder limit for the group: The feeder will be called whenever
1099the group contains less than this many requests. 1402the group contains less than this many requests.
1100 1403
1101Setting the limit to C<0> will pause the feeding process. 1404Setting the limit to C<0> will pause the feeding process.
1102 1405
1406The default value for the limit is C<0>, but note that setting a feeder
1407automatically bumps it up to C<2>.
1408
1103=back 1409=back
1104 1410
1105=head2 SUPPORT FUNCTIONS 1411=head2 SUPPORT FUNCTIONS
1106 1412
1107=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 1413=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
… …
1109=over 4 1415=over 4
1110 1416
1111=item $fileno = IO::AIO::poll_fileno 1417=item $fileno = IO::AIO::poll_fileno
1112 1418
1113Return the I<request result pipe file descriptor>. This filehandle must be 1419Return the I<request result pipe file descriptor>. This filehandle must be
1114polled for reading by some mechanism outside this module (e.g. Event or 1420polled for reading by some mechanism outside this module (e.g. EV, Glib,
1115select, see below or the SYNOPSIS). If the pipe becomes readable you have 1421select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1116to call C<poll_cb> to check the results. 1422you have to call C<poll_cb> to check the results.
1117 1423
1118See C<poll_cb> for an example. 1424See C<poll_cb> for an example.
1119 1425
1120=item IO::AIO::poll_cb 1426=item IO::AIO::poll_cb
1121 1427
1122Process some outstanding events on the result pipe. You have to call this 1428Process some outstanding events on the result pipe. You have to call
1123regularly. Returns C<0> if all events could be processed, or C<-1> if it 1429this regularly. Returns C<0> if all events could be processed (or there
1124returned earlier for whatever reason. Returns immediately when no events 1430were no events to process), or C<-1> if it returned earlier for whatever
1125are outstanding. The amount of events processed depends on the settings of 1431reason. Returns immediately when no events are outstanding. The amount of
1126C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1432events processed depends on the settings of C<IO::AIO::max_poll_req> and
1433C<IO::AIO::max_poll_time>.
1127 1434
1128If not all requests were processed for whatever reason, the filehandle 1435If not all requests were processed for whatever reason, the filehandle
1129will still be ready when C<poll_cb> returns, so normally you don't have to 1436will still be ready when C<poll_cb> returns, so normally you don't have to
1130do anything special to have it called later. 1437do anything special to have it called later.
1131 1438
1439Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1440ready, it can be beneficial to call this function from loops which submit
1441a lot of requests, to make sure the results get processed when they become
1442available and not just when the loop is finished and the event loop takes
1443over again. This function returns very fast when there are no outstanding
1444requests.
1445
1132Example: Install an Event watcher that automatically calls 1446Example: Install an Event watcher that automatically calls
1133IO::AIO::poll_cb with high priority: 1447IO::AIO::poll_cb with high priority (more examples can be found in the
1448SYNOPSIS section, at the top of this document):
1134 1449
1135 Event->io (fd => IO::AIO::poll_fileno, 1450 Event->io (fd => IO::AIO::poll_fileno,
1136 poll => 'r', async => 1, 1451 poll => 'r', async => 1,
1137 cb => \&IO::AIO::poll_cb); 1452 cb => \&IO::AIO::poll_cb);
1453
1454=item IO::AIO::poll_wait
1455
1456If there are any outstanding requests and none of them in the result
1457phase, wait till the result filehandle becomes ready for reading (simply
1458does a C<select> on the filehandle. This is useful if you want to
1459synchronously wait for some requests to finish).
1460
1461See C<nreqs> for an example.
1462
1463=item IO::AIO::poll
1464
1465Waits until some requests have been handled.
1466
1467Returns the number of requests processed, but is otherwise strictly
1468equivalent to:
1469
1470 IO::AIO::poll_wait, IO::AIO::poll_cb
1471
1472=item IO::AIO::flush
1473
1474Wait till all outstanding AIO requests have been handled.
1475
1476Strictly equivalent to:
1477
1478 IO::AIO::poll_wait, IO::AIO::poll_cb
1479 while IO::AIO::nreqs;
1138 1480
1139=item IO::AIO::max_poll_reqs $nreqs 1481=item IO::AIO::max_poll_reqs $nreqs
1140 1482
1141=item IO::AIO::max_poll_time $seconds 1483=item IO::AIO::max_poll_time $seconds
1142 1484
… …
1167 # use a low priority so other tasks have priority 1509 # use a low priority so other tasks have priority
1168 Event->io (fd => IO::AIO::poll_fileno, 1510 Event->io (fd => IO::AIO::poll_fileno,
1169 poll => 'r', nice => 1, 1511 poll => 'r', nice => 1,
1170 cb => &IO::AIO::poll_cb); 1512 cb => &IO::AIO::poll_cb);
1171 1513
1172=item IO::AIO::poll_wait
1173
1174If there are any outstanding requests and none of them in the result
1175phase, wait till the result filehandle becomes ready for reading (simply
1176does a C<select> on the filehandle. This is useful if you want to
1177synchronously wait for some requests to finish).
1178
1179See C<nreqs> for an example.
1180
1181=item IO::AIO::poll
1182
1183Waits until some requests have been handled.
1184
1185Returns the number of requests processed, but is otherwise strictly
1186equivalent to:
1187
1188 IO::AIO::poll_wait, IO::AIO::poll_cb
1189
1190=item IO::AIO::flush
1191
1192Wait till all outstanding AIO requests have been handled.
1193
1194Strictly equivalent to:
1195
1196 IO::AIO::poll_wait, IO::AIO::poll_cb
1197 while IO::AIO::nreqs;
1198
1199=back 1514=back
1200 1515
1201=head3 CONTROLLING THE NUMBER OF THREADS 1516=head3 CONTROLLING THE NUMBER OF THREADS
1202 1517
1203=over 1518=over
… …
1236 1551
1237Under normal circumstances you don't need to call this function. 1552Under normal circumstances you don't need to call this function.
1238 1553
1239=item IO::AIO::max_idle $nthreads 1554=item IO::AIO::max_idle $nthreads
1240 1555
1241Limit the number of threads (default: 4) that are allowed to idle (i.e., 1556Limit the number of threads (default: 4) that are allowed to idle
1242threads that did not get a request to process within 10 seconds). That 1557(i.e., threads that did not get a request to process within the idle
1243means if a thread becomes idle while C<$nthreads> other threads are also 1558timeout (default: 10 seconds). That means if a thread becomes idle while
1244idle, it will free its resources and exit. 1559C<$nthreads> other threads are also idle, it will free its resources and
1560exit.
1245 1561
1246This is useful when you allow a large number of threads (e.g. 100 or 1000) 1562This is useful when you allow a large number of threads (e.g. 100 or 1000)
1247to allow for extremely high load situations, but want to free resources 1563to allow for extremely high load situations, but want to free resources
1248under normal circumstances (1000 threads can easily consume 30MB of RAM). 1564under normal circumstances (1000 threads can easily consume 30MB of RAM).
1249 1565
1250The default is probably ok in most situations, especially if thread 1566The default is probably ok in most situations, especially if thread
1251creation is fast. If thread creation is very slow on your system you might 1567creation is fast. If thread creation is very slow on your system you might
1252want to use larger values. 1568want to use larger values.
1253 1569
1570=item IO::AIO::idle_timeout $seconds
1571
1572Sets the minimum idle timeout (default 10) after which worker threads are
1573allowed to exit. SEe C<IO::AIO::max_idle>.
1574
1254=item IO::AIO::max_outstanding $maxreqs 1575=item IO::AIO::max_outstanding $maxreqs
1576
1577Sets the maximum number of outstanding requests to C<$nreqs>. If
1578you do queue up more than this number of requests, the next call to
1579C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1580C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1581longer exceeded.
1582
1583In other words, this setting does not enforce a queue limit, but can be
1584used to make poll functions block if the limit is exceeded.
1255 1585
1256This is a very bad function to use in interactive programs because it 1586This is a very bad function to use in interactive programs because it
1257blocks, and a bad way to reduce concurrency because it is inexact: Better 1587blocks, and a bad way to reduce concurrency because it is inexact: Better
1258use an C<aio_group> together with a feed callback. 1588use an C<aio_group> together with a feed callback.
1259 1589
1260Sets the maximum number of outstanding requests to C<$nreqs>. If you 1590It's main use is in scripts without an event loop - when you want to stat
1261do queue up more than this number of requests, the next call to the 1591a lot of files, you can write somehting like this:
1262C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1263function will block until the limit is no longer exceeded.
1264 1592
1265The default value is very large, so there is no practical limit on the 1593 IO::AIO::max_outstanding 32;
1266number of outstanding requests.
1267 1594
1268You can still queue as many requests as you want. Therefore, 1595 for my $path (...) {
1269C<max_outstanding> is mainly useful in simple scripts (with low values) or 1596 aio_stat $path , ...;
1270as a stop gap to shield against fatal memory overflow (with large values). 1597 IO::AIO::poll_cb;
1598 }
1599
1600 IO::AIO::flush;
1601
1602The call to C<poll_cb> inside the loop will normally return instantly, but
1603as soon as more thna C<32> reqeusts are in-flight, it will block until
1604some requests have been handled. This keeps the loop from pushing a large
1605number of C<aio_stat> requests onto the queue.
1606
1607The default value for C<max_outstanding> is very large, so there is no
1608practical limit on the number of outstanding requests.
1271 1609
1272=back 1610=back
1273 1611
1274=head3 STATISTICAL INFORMATION 1612=head3 STATISTICAL INFORMATION
1275 1613
… …
1295Returns the number of requests currently in the pending state (executed, 1633Returns the number of requests currently in the pending state (executed,
1296but not yet processed by poll_cb). 1634but not yet processed by poll_cb).
1297 1635
1298=back 1636=back
1299 1637
1638=head3 MISCELLANEOUS FUNCTIONS
1639
1640IO::AIO implements some functions that might be useful, but are not
1641asynchronous.
1642
1643=over 4
1644
1645=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1646
1647Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1648but is blocking (this makes most sense if you know the input data is
1649likely cached already and the output filehandle is set to non-blocking
1650operations).
1651
1652Returns the number of bytes copied, or C<-1> on error.
1653
1654=item IO::AIO::fadvise $fh, $offset, $len, $advice
1655
1656Simply calls the C<posix_fadvise> function (see its
1657manpage for details). The following advice constants are
1658avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1659C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1660C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1661
1662On systems that do not implement C<posix_fadvise>, this function returns
1663ENOSYS, otherwise the return value of C<posix_fadvise>.
1664
1665=item IO::AIO::madvise $scalar, $offset, $len, $advice
1666
1667Simply calls the C<posix_madvise> function (see its
1668manpage for details). The following advice constants are
1669avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1670C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1671
1672On systems that do not implement C<posix_madvise>, this function returns
1673ENOSYS, otherwise the return value of C<posix_madvise>.
1674
1675=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1676
1677Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1678$scalar (see its manpage for details). The following protect
1679constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1680C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1681
1682On systems that do not implement C<mprotect>, this function returns
1683ENOSYS, otherwise the return value of C<mprotect>.
1684
1685=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1686
1687Memory-maps a file (or anonymous memory range) and attaches it to the
1688given C<$scalar>, which will act like a string scalar.
1689
1690The only operations allowed on the scalar are C<substr>/C<vec> that don't
1691change the string length, and most read-only operations such as copying it
1692or searching it with regexes and so on.
1693
1694Anything else is unsafe and will, at best, result in memory leaks.
1695
1696The memory map associated with the C<$scalar> is automatically removed
1697when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
1698C<IO::AIO::munmap> functions are called.
1699
1700This calls the C<mmap>(2) function internally. See your system's manual
1701page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1702
1703The C<$length> must be larger than zero and smaller than the actual
1704filesize.
1705
1706C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1707C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1708
1709C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
1710C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
1711not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
1712(which is set to C<MAP_ANON> if your system only provides this
1713constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
1714C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1715C<IO::AIO::MAP_NONBLOCK>
1716
1717If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1718
1719C<$offset> is the offset from the start of the file - it generally must be
1720a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1721
1722Example:
1723
1724 use Digest::MD5;
1725 use IO::AIO;
1726
1727 open my $fh, "<verybigfile"
1728 or die "$!";
1729
1730 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1731 or die "verybigfile: $!";
1732
1733 my $fast_md5 = md5 $data;
1734
1735=item IO::AIO::munmap $scalar
1736
1737Removes a previous mmap and undefines the C<$scalar>.
1738
1739=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1740
1741Calls the C<munlock> function, undoing the effects of a previous
1742C<aio_mlock> call (see its description for details).
1743
1744=item IO::AIO::munlockall
1745
1746Calls the C<munlockall> function.
1747
1748On systems that do not implement C<munlockall>, this function returns
1749ENOSYS, otherwise the return value of C<munlockall>.
1750
1751=back
1752
1300=cut 1753=cut
1301 1754
1302min_parallel 8; 1755min_parallel 8;
1303 1756
1304END { flush } 1757END { flush }
1305 1758
13061; 17591;
1307 1760
1761=head1 EVENT LOOP INTEGRATION
1762
1763It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
1764automatically into many event loops:
1765
1766 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1767 use AnyEvent::AIO;
1768
1769You can also integrate IO::AIO manually into many event loops, here are
1770some examples of how to do this:
1771
1772 # EV integration
1773 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1774
1775 # Event integration
1776 Event->io (fd => IO::AIO::poll_fileno,
1777 poll => 'r',
1778 cb => \&IO::AIO::poll_cb);
1779
1780 # Glib/Gtk2 integration
1781 add_watch Glib::IO IO::AIO::poll_fileno,
1782 in => sub { IO::AIO::poll_cb; 1 };
1783
1784 # Tk integration
1785 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1786 readable => \&IO::AIO::poll_cb);
1787
1788 # Danga::Socket integration
1789 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1790 \&IO::AIO::poll_cb);
1791
1308=head2 FORK BEHAVIOUR 1792=head2 FORK BEHAVIOUR
1309 1793
1310This module should do "the right thing" when the process using it forks: 1794Usage of pthreads in a program changes the semantics of fork
1795considerably. Specifically, only async-safe functions can be called after
1796fork. Perl doesn't know about this, so in general, you cannot call fork
1797with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
1798but many other extensions and (for inexplicable reasons) perl itself often
1799is linked against pthreads, so this limitation applies.
1311 1800
1312Before the fork, IO::AIO enters a quiescent state where no requests 1801Some operating systems have extensions that allow safe use of fork, and
1313can be added in other threads and no results will be processed. After 1802this module should do "the right thing" on those, and tries on others. At
1314the fork the parent simply leaves the quiescent state and continues 1803the time of this writing (2011) only GNU/Linux supports these extensions
1315request/result processing, while the child frees the request/result queue 1804to POSIX.
1316(so that the requests started before the fork will only be handled in the
1317parent). Threads will be started on demand until the limit set in the
1318parent process has been reached again.
1319
1320In short: the parent will, after a short pause, continue as if fork had
1321not been called, while the child will act as if IO::AIO has not been used
1322yet.
1323 1805
1324=head2 MEMORY USAGE 1806=head2 MEMORY USAGE
1325 1807
1326Per-request usage: 1808Per-request usage:
1327 1809

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