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Revision 1.145 by root, Sun Apr 19 19:20:10 2009 UTC vs.
Revision 1.206 by root, Sun Jul 24 03:32:51 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 = '3.18'; 173 our $VERSION = '4.0';
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_realpath aio_sync
203 aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead 178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
179 aio_pathsync aio_readahead
204 aio_rename aio_link aio_move aio_copy aio_group 180 aio_rename aio_link aio_move aio_copy aio_group
205 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 181 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206 aio_chmod aio_utime aio_truncate); 182 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs);
207 185
208 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 186 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 187 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210 min_parallel max_parallel max_idle 188 min_parallel max_parallel max_idle idle_timeout
211 nreqs nready npending nthreads 189 nreqs nready npending nthreads
212 max_poll_time max_poll_reqs); 190 max_poll_time max_poll_reqs
191 sendfile fadvise madvise
192 mmap munmap munlock munlockall);
213 193
214 push @AIO_REQ, qw(aio_busy); # not exported 194 push @AIO_REQ, qw(aio_busy); # not exported
215 195
216 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 196 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217 197
218 require XSLoader; 198 require XSLoader;
219 XSLoader::load ("IO::AIO", $VERSION); 199 XSLoader::load ("IO::AIO", $VERSION);
220} 200}
221 201
222=head1 FUNCTIONS 202=head1 FUNCTIONS
203
204=head2 QUICK OVERVIEW
205
206This section simply lists the prototypes of the most important functions
207for quick reference. See the following sections for function-by-function
208documentation.
209
210 aio_open $pathname, $flags, $mode, $callback->($fh)
211 aio_close $fh, $callback->($status)
212 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
214 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
215 aio_readahead $fh,$offset,$length, $callback->($retval)
216 aio_stat $fh_or_path, $callback->($status)
217 aio_lstat $fh, $callback->($status)
218 aio_statvfs $fh_or_path, $callback->($statvfs)
219 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
220 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
221 aio_truncate $fh_or_path, $offset, $callback->($status)
222 aio_chmod $fh_or_path, $mode, $callback->($status)
223 aio_unlink $pathname, $callback->($status)
224 aio_mknod $path, $mode, $dev, $callback->($status)
225 aio_link $srcpath, $dstpath, $callback->($status)
226 aio_symlink $srcpath, $dstpath, $callback->($status)
227 aio_readlink $path, $callback->($link)
228 aio_realpath $path, $callback->($link)
229 aio_rename $srcpath, $dstpath, $callback->($status)
230 aio_mkdir $pathname, $mode, $callback->($status)
231 aio_rmdir $pathname, $callback->($status)
232 aio_readdir $pathname, $callback->($entries)
233 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
234 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
235 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
236 aio_load $path, $data, $callback->($status)
237 aio_copy $srcpath, $dstpath, $callback->($status)
238 aio_move $srcpath, $dstpath, $callback->($status)
239 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
240 aio_rmtree $path, $callback->($status)
241 aio_sync $callback->($status)
242 aio_syncfs $fh, $callback->($status)
243 aio_fsync $fh, $callback->($status)
244 aio_fdatasync $fh, $callback->($status)
245 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
246 aio_pathsync $path, $callback->($status)
247 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
248 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
249 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
250 aio_mlockall $flags, $callback->($status)
251 aio_group $callback->(...)
252 aio_nop $callback->()
253
254 $prev_pri = aioreq_pri [$pri]
255 aioreq_nice $pri_adjust
256
257 IO::AIO::poll_wait
258 IO::AIO::poll_cb
259 IO::AIO::poll
260 IO::AIO::flush
261 IO::AIO::max_poll_reqs $nreqs
262 IO::AIO::max_poll_time $seconds
263 IO::AIO::min_parallel $nthreads
264 IO::AIO::max_parallel $nthreads
265 IO::AIO::max_idle $nthreads
266 IO::AIO::idle_timeout $seconds
267 IO::AIO::max_outstanding $maxreqs
268 IO::AIO::nreqs
269 IO::AIO::nready
270 IO::AIO::npending
271
272 IO::AIO::sendfile $ofh, $ifh, $offset, $count
273 IO::AIO::fadvise $fh, $offset, $len, $advice
274 IO::AIO::madvise $scalar, $offset, $length, $advice
275 IO::AIO::mprotect $scalar, $offset, $length, $protect
276 IO::AIO::munlock $scalar, $offset = 0, $length = undef
277 IO::AIO::munlockall
223 278
224=head2 AIO REQUEST FUNCTIONS 279=head2 AIO REQUEST FUNCTIONS
225 280
226All the C<aio_*> calls are more or less thin wrappers around the syscall 281All the C<aio_*> calls are more or less thin wrappers around the syscall
227with the same name (sans C<aio_>). The arguments are similar or identical, 282with the same name (sans C<aio_>). The arguments are similar or identical,
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307by the umask in effect then the request is being executed, so better never 362by the umask in effect then the request is being executed, so better never
308change the umask. 363change the umask.
309 364
310Example: 365Example:
311 366
312 aio_open "/etc/passwd", O_RDONLY, 0, sub { 367 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313 if ($_[0]) { 368 if ($_[0]) {
314 print "open successful, fh is $_[0]\n"; 369 print "open successful, fh is $_[0]\n";
315 ... 370 ...
316 } else { 371 } else {
317 die "open failed: $!\n"; 372 die "open failed: $!\n";
318 } 373 }
319 }; 374 };
320 375
376In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
377C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
378following POSIX and non-POSIX constants are available (missing ones on
379your system are, as usual, C<0>):
380
381C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
382C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
383C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
384
321 385
322=item aio_close $fh, $callback->($status) 386=item aio_close $fh, $callback->($status)
323 387
324Asynchronously close a file and call the callback with the result 388Asynchronously close a file and call the callback with the result
325code. 389code.
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343Reads or writes C<$length> bytes from or to the specified C<$fh> and 407Reads or writes C<$length> bytes from or to the specified C<$fh> and
344C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> 408C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
345and calls the callback without the actual number of bytes read (or -1 on 409and calls the callback without the actual number of bytes read (or -1 on
346error, just like the syscall). 410error, just like the syscall).
347 411
412C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
413offset plus the actual number of bytes read.
414
348If C<$offset> is undefined, then the current file descriptor offset will 415If C<$offset> is undefined, then the current file descriptor offset will
349be used (and updated), otherwise the file descriptor offset will not be 416be used (and updated), otherwise the file descriptor offset will not be
350changed by these calls. 417changed by these calls.
351 418
352If C<$length> is undefined in C<aio_write>, use the remaining length of 419If C<$length> is undefined in C<aio_write>, use the remaining length of
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372 439
373Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 440Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
374reading at byte offset C<$in_offset>, and starts writing at the current 441reading at byte offset C<$in_offset>, and starts writing at the current
375file offset of C<$out_fh>. Because of that, it is not safe to issue more 442file offset of C<$out_fh>. Because of that, it is not safe to issue more
376than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 443than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
377other. 444other. The same C<$in_fh> works fine though, as this function does not
445move or use the file offset of C<$in_fh>.
378 446
447Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
448are written, and there is no way to find out how many more bytes have been
449read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
450number of bytes written to C<$out_fh>. Only if the result value equals
451C<$length> one can assume that C<$length> bytes have been read.
452
453Unlike with other C<aio_> functions, it makes a lot of sense to use
454C<aio_sendfile> on non-blocking sockets, as long as one end (typically
455the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
456the socket I/O will be non-blocking. Note, however, that you can run
457into a trap where C<aio_sendfile> reads some data with readahead, then
458fails to write all data, and when the socket is ready the next time, the
459data in the cache is already lost, forcing C<aio_sendfile> to again hit
460the disk. Explicit C<aio_read> + C<aio_write> let's you better control
461resource usage.
462
379This call tries to make use of a native C<sendfile> syscall to provide 463This call tries to make use of a native C<sendfile>-like syscall to
380zero-copy operation. For this to work, C<$out_fh> should refer to a 464provide zero-copy operation. For this to work, C<$out_fh> should refer to
381socket, and C<$in_fh> should refer to mmap'able file. 465a socket, and C<$in_fh> should refer to an mmap'able file.
382 466
383If the native sendfile call fails or is not implemented, it will be 467If a native sendfile cannot be found or it fails with C<ENOSYS>,
384emulated, so you can call C<aio_sendfile> on any type of filehandle 468C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
469C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
385regardless of the limitations of the operating system. 470type of filehandle regardless of the limitations of the operating system.
386 471
387Please note, however, that C<aio_sendfile> can read more bytes from 472As native sendfile syscalls (as practically any non-POSIX interface hacked
388C<$in_fh> than are written, and there is no way to find out how many 473together in a hurry to improve benchmark numbers) tend to be rather buggy
389bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 474on many systems, this implementation tries to work around some known bugs
390provides the number of bytes written to C<$out_fh>. Only if the result 475in Linux and FreeBSD kernels (probably others, too), but that might fail,
391value equals C<$length> one can assume that C<$length> bytes have been 476so you really really should check the return value of C<aio_sendfile> -
392read. 477fewre bytes than expected might have been transferred.
393 478
394 479
395=item aio_readahead $fh,$offset,$length, $callback->($retval) 480=item aio_readahead $fh,$offset,$length, $callback->($retval)
396 481
397C<aio_readahead> populates the page cache with data from a file so that 482C<aio_readahead> populates the page cache with data from a file so that
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420 505
421Currently, the stats are always 64-bit-stats, i.e. instead of returning an 506Currently, the stats are always 64-bit-stats, i.e. instead of returning an
422error when stat'ing a large file, the results will be silently truncated 507error when stat'ing a large file, the results will be silently truncated
423unless perl itself is compiled with large file support. 508unless perl itself is compiled with large file support.
424 509
510To help interpret the mode and dev/rdev stat values, IO::AIO offers the
511following constants and functions (if not implemented, the constants will
512be C<0> and the functions will either C<croak> or fall back on traditional
513behaviour).
514
515C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
516C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
517C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
518
425Example: Print the length of F</etc/passwd>: 519Example: Print the length of F</etc/passwd>:
426 520
427 aio_stat "/etc/passwd", sub { 521 aio_stat "/etc/passwd", sub {
428 $_[0] and die "stat failed: $!"; 522 $_[0] and die "stat failed: $!";
429 print "size is ", -s _, "\n"; 523 print "size is ", -s _, "\n";
430 }; 524 };
431 525
432 526
527=item aio_statvfs $fh_or_path, $callback->($statvfs)
528
529Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
530whether a file handle or path was passed.
531
532On success, the callback is passed a hash reference with the following
533members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
534C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
535is passed.
536
537The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
538C<ST_NOSUID>.
539
540The following non-POSIX IO::AIO::ST_* flag masks are defined to
541their correct value when available, or to C<0> on systems that do
542not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
543C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
544C<ST_NODIRATIME> and C<ST_RELATIME>.
545
546Example: stat C</wd> and dump out the data if successful.
547
548 aio_statvfs "/wd", sub {
549 my $f = $_[0]
550 or die "statvfs: $!";
551
552 use Data::Dumper;
553 say Dumper $f;
554 };
555
556 # result:
557 {
558 bsize => 1024,
559 bfree => 4333064312,
560 blocks => 10253828096,
561 files => 2050765568,
562 flag => 4096,
563 favail => 2042092649,
564 bavail => 4333064312,
565 ffree => 2042092649,
566 namemax => 255,
567 frsize => 1024,
568 fsid => 1810
569 }
570
571
433=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 572=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
434 573
435Works like perl's C<utime> function (including the special case of $atime 574Works like perl's C<utime> function (including the special case of $atime
436and $mtime being undef). Fractional times are supported if the underlying 575and $mtime being undef). Fractional times are supported if the underlying
437syscalls support them. 576syscalls support them.
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485 624
486The only (POSIX-) portable way of calling this function is: 625The only (POSIX-) portable way of calling this function is:
487 626
488 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 627 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
489 628
629See C<aio_stat> for info about some potentially helpful extra constants
630and functions.
490 631
491=item aio_link $srcpath, $dstpath, $callback->($status) 632=item aio_link $srcpath, $dstpath, $callback->($status)
492 633
493Asynchronously create a new link to the existing object at C<$srcpath> at 634Asynchronously create a new link to the existing object at C<$srcpath> at
494the path C<$dstpath> and call the callback with the result code. 635the path C<$dstpath> and call the callback with the result code.
… …
505Asynchronously read the symlink specified by C<$path> and pass it to 646Asynchronously read the symlink specified by C<$path> and pass it to
506the callback. If an error occurs, nothing or undef gets passed to the 647the callback. If an error occurs, nothing or undef gets passed to the
507callback. 648callback.
508 649
509 650
651=item aio_realpath $path, $callback->($path)
652
653Asynchronously make the path absolute and resolve any symlinks in
654C<$path>. The resulting path only consists of directories (Same as
655L<Cwd::realpath>).
656
657This request can be used to get the absolute path of the current working
658directory by passing it a path of F<.> (a single dot).
659
660
510=item aio_rename $srcpath, $dstpath, $callback->($status) 661=item aio_rename $srcpath, $dstpath, $callback->($status)
511 662
512Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 663Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
513rename(2) and call the callback with the result code. 664rename(2) and call the callback with the result code.
514 665
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530 681
531Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 682Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
532directory (i.e. opendir + readdir + closedir). The entries will not be 683directory (i.e. opendir + readdir + closedir). The entries will not be
533sorted, and will B<NOT> include the C<.> and C<..> entries. 684sorted, and will B<NOT> include the C<.> and C<..> entries.
534 685
535The callback a single argument which is either C<undef> or an array-ref 686The callback is passed a single argument which is either C<undef> or an
536with the filenames. 687array-ref with the filenames.
688
689
690=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
691
692Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
693behaviour and output format. In case of an error, C<$entries> will be
694C<undef>.
695
696The flags are a combination of the following constants, ORed together (the
697flags will also be passed to the callback, possibly modified):
698
699=over 4
700
701=item IO::AIO::READDIR_DENTS
702
703When this flag is off, then the callback gets an arrayref consisting of
704names only (as with C<aio_readdir>), otherwise it gets an arrayref with
705C<[$name, $type, $inode]> arrayrefs, each describing a single directory
706entry in more detail.
707
708C<$name> is the name of the entry.
709
710C<$type> is one of the C<IO::AIO::DT_xxx> constants:
711
712C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
713C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
714C<IO::AIO::DT_WHT>.
715
716C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
717know, you have to run stat yourself. Also, for speed reasons, the C<$type>
718scalars are read-only: you can not modify them.
719
720C<$inode> is the inode number (which might not be exact on systems with 64
721bit inode numbers and 32 bit perls). This field has unspecified content on
722systems that do not deliver the inode information.
723
724=item IO::AIO::READDIR_DIRS_FIRST
725
726When this flag is set, then the names will be returned in an order where
727likely directories come first, in optimal stat order. This is useful when
728you need to quickly find directories, or you want to find all directories
729while avoiding to stat() each entry.
730
731If the system returns type information in readdir, then this is used
732to find directories directly. Otherwise, likely directories are names
733beginning with ".", or otherwise names with no dots, of which names with
734short names are tried first.
735
736=item IO::AIO::READDIR_STAT_ORDER
737
738When this flag is set, then the names will be returned in an order
739suitable for stat()'ing each one. That is, when you plan to stat()
740all files in the given directory, then the returned order will likely
741be fastest.
742
743If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
744the likely dirs come first, resulting in a less optimal stat order.
745
746=item IO::AIO::READDIR_FOUND_UNKNOWN
747
748This flag should not be set when calling C<aio_readdirx>. Instead, it
749is being set by C<aio_readdirx>, when any of the C<$type>'s found were
750C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
751C<$type>'s are known, which can be used to speed up some algorithms.
752
753=back
537 754
538 755
539=item aio_load $path, $data, $callback->($status) 756=item aio_load $path, $data, $callback->($status)
540 757
541This is a composite request that tries to fully load the given file into 758This is a composite request that tries to fully load the given file into
… …
566 783
567=item aio_copy $srcpath, $dstpath, $callback->($status) 784=item aio_copy $srcpath, $dstpath, $callback->($status)
568 785
569Try to copy the I<file> (directories not supported as either source or 786Try to copy the I<file> (directories not supported as either source or
570destination) from C<$srcpath> to C<$dstpath> and call the callback with 787destination) from C<$srcpath> to C<$dstpath> and call the callback with
571the C<0> (error) or C<-1> ok. 788a status of C<0> (ok) or C<-1> (error, see C<$!>).
572 789
573This is a composite request that creates the destination file with 790This is a composite request that creates the destination file with
574mode 0200 and copies the contents of the source file into it using 791mode 0200 and copies the contents of the source file into it using
575C<aio_sendfile>, followed by restoring atime, mtime, access mode and 792C<aio_sendfile>, followed by restoring atime, mtime, access mode and
576uid/gid, in that order. 793uid/gid, in that order.
… …
588 my $grp = aio_group $cb; 805 my $grp = aio_group $cb;
589 806
590 aioreq_pri $pri; 807 aioreq_pri $pri;
591 add $grp aio_open $src, O_RDONLY, 0, sub { 808 add $grp aio_open $src, O_RDONLY, 0, sub {
592 if (my $src_fh = $_[0]) { 809 if (my $src_fh = $_[0]) {
593 my @stat = stat $src_fh; 810 my @stat = stat $src_fh; # hmm, might block over nfs?
594 811
595 aioreq_pri $pri; 812 aioreq_pri $pri;
596 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { 813 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
597 if (my $dst_fh = $_[0]) { 814 if (my $dst_fh = $_[0]) {
598 aioreq_pri $pri; 815 aioreq_pri $pri;
599 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { 816 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
600 if ($_[0] == $stat[7]) { 817 if ($_[0] == $stat[7]) {
601 $grp->result (0); 818 $grp->result (0);
602 close $src_fh; 819 close $src_fh;
603 820
604 # those should not normally block. should. should. 821 my $ch = sub {
605 utime $stat[8], $stat[9], $dst; 822 aioreq_pri $pri;
606 chmod $stat[2] & 07777, $dst_fh; 823 add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
607 chown $stat[4], $stat[5], $dst_fh; 824 aioreq_pri $pri;
825 add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
826 aioreq_pri $pri;
827 add $grp aio_close $dst_fh;
828 }
829 };
830 };
608 831
609 aioreq_pri $pri; 832 aioreq_pri $pri;
610 add $grp aio_close $dst_fh; 833 add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
834 if ($_[0] < 0 && $! == ENOSYS) {
835 aioreq_pri $pri;
836 add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
837 } else {
838 $ch->();
839 }
840 };
611 } else { 841 } else {
612 $grp->result (-1); 842 $grp->result (-1);
613 close $src_fh; 843 close $src_fh;
614 close $dst_fh; 844 close $dst_fh;
615 845
… …
632 862
633=item aio_move $srcpath, $dstpath, $callback->($status) 863=item aio_move $srcpath, $dstpath, $callback->($status)
634 864
635Try to move the I<file> (directories not supported as either source or 865Try to move the I<file> (directories not supported as either source or
636destination) from C<$srcpath> to C<$dstpath> and call the callback with 866destination) from C<$srcpath> to C<$dstpath> and call the callback with
637the C<0> (error) or C<-1> ok. 867a status of C<0> (ok) or C<-1> (error, see C<$!>).
638 868
639This is a composite request that tries to rename(2) the file first; if 869This is a composite request that tries to rename(2) the file first; if
640rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if 870rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
641that is successful, unlinks the C<$srcpath>. 871that is successful, unlinks the C<$srcpath>.
642 872
… …
653 if ($_[0] && $! == EXDEV) { 883 if ($_[0] && $! == EXDEV) {
654 aioreq_pri $pri; 884 aioreq_pri $pri;
655 add $grp aio_copy $src, $dst, sub { 885 add $grp aio_copy $src, $dst, sub {
656 $grp->result ($_[0]); 886 $grp->result ($_[0]);
657 887
658 if (!$_[0]) { 888 unless ($_[0]) {
659 aioreq_pri $pri; 889 aioreq_pri $pri;
660 add $grp aio_unlink $src; 890 add $grp aio_unlink $src;
661 } 891 }
662 }; 892 };
663 } else { 893 } else {
… …
693 923
694Implementation notes. 924Implementation notes.
695 925
696The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. 926The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
697 927
928If readdir returns file type information, then this is used directly to
929find directories.
930
698After reading the directory, the modification time, size etc. of the 931Otherwise, after reading the directory, the modification time, size etc.
699directory before and after the readdir is checked, and if they match (and 932of the directory before and after the readdir is checked, and if they
700isn't the current time), the link count will be used to decide how many 933match (and isn't the current time), the link count will be used to decide
701entries are directories (if >= 2). Otherwise, no knowledge of the number 934how many entries are directories (if >= 2). Otherwise, no knowledge of the
702of subdirectories will be assumed. 935number of subdirectories will be assumed.
703 936
704Then entries will be sorted into likely directories (everything without 937Then entries will be sorted into likely directories a non-initial dot
705a non-initial dot currently) and likely non-directories (everything 938currently) and likely non-directories (see C<aio_readdirx>). Then every
706else). Then every entry plus an appended C</.> will be C<stat>'ed, 939entry plus an appended C</.> will be C<stat>'ed, likely directories first,
707likely directories first. If that succeeds, it assumes that the entry 940in order of their inode numbers. If that succeeds, it assumes that the
708is a directory or a symlink to directory (which will be checked 941entry is a directory or a symlink to directory (which will be checked
709seperately). This is often faster than stat'ing the entry itself because 942seperately). This is often faster than stat'ing the entry itself because
710filesystems might detect the type of the entry without reading the inode 943filesystems might detect the type of the entry without reading the inode
711data (e.g. ext2fs filetype feature). 944data (e.g. ext2fs filetype feature), even on systems that cannot return
945the filetype information on readdir.
712 946
713If the known number of directories (link count - 2) has been reached, the 947If the known number of directories (link count - 2) has been reached, the
714rest of the entries is assumed to be non-directories. 948rest of the entries is assumed to be non-directories.
715 949
716This only works with certainty on POSIX (= UNIX) filesystems, which 950This only works with certainty on POSIX (= UNIX) filesystems, which
… …
738 my $now = time; 972 my $now = time;
739 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 973 my $hash1 = join ":", (stat _)[0,1,3,7,9];
740 974
741 # read the directory entries 975 # read the directory entries
742 aioreq_pri $pri; 976 aioreq_pri $pri;
743 add $grp aio_readdir $path, sub { 977 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
744 my $entries = shift 978 my $entries = shift
745 or return $grp->result (); 979 or return $grp->result ();
746 980
747 # stat the dir another time 981 # stat the dir another time
748 aioreq_pri $pri; 982 aioreq_pri $pri;
… …
754 # take the slow route if anything looks fishy 988 # take the slow route if anything looks fishy
755 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 989 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
756 $ndirs = -1; 990 $ndirs = -1;
757 } else { 991 } else {
758 # if nlink == 2, we are finished 992 # if nlink == 2, we are finished
759 # on non-posix-fs's, we rely on nlink < 2 993 # for non-posix-fs's, we rely on nlink < 2
760 $ndirs = (stat _)[3] - 2 994 $ndirs = (stat _)[3] - 2
761 or return $grp->result ([], $entries); 995 or return $grp->result ([], $entries);
762 } 996 }
763 997
764 # sort into likely dirs and likely nondirs
765 # dirs == files without ".", short entries first
766 $entries = [map $_->[0],
767 sort { $b->[1] cmp $a->[1] }
768 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
769 @$entries];
770
771 my (@dirs, @nondirs); 998 my (@dirs, @nondirs);
772 999
773 my $statgrp = add $grp aio_group sub { 1000 my $statgrp = add $grp aio_group sub {
774 $grp->result (\@dirs, \@nondirs); 1001 $grp->result (\@dirs, \@nondirs);
775 }; 1002 };
776 1003
777 limit $statgrp $maxreq; 1004 limit $statgrp $maxreq;
778 feed $statgrp sub { 1005 feed $statgrp sub {
779 return unless @$entries; 1006 return unless @$entries;
780 my $entry = pop @$entries; 1007 my $entry = shift @$entries;
781 1008
782 aioreq_pri $pri; 1009 aioreq_pri $pri;
783 add $statgrp aio_stat "$path/$entry/.", sub { 1010 add $statgrp aio_stat "$path/$entry/.", sub {
784 if ($_[0] < 0) { 1011 if ($_[0] < 0) {
785 push @nondirs, $entry; 1012 push @nondirs, $entry;
… …
858callback with the fdatasync result code. 1085callback with the fdatasync result code.
859 1086
860If this call isn't available because your OS lacks it or it couldn't be 1087If this call isn't available because your OS lacks it or it couldn't be
861detected, it will be emulated by calling C<fsync> instead. 1088detected, it will be emulated by calling C<fsync> instead.
862 1089
1090=item aio_syncfs $fh, $callback->($status)
1091
1092Asynchronously call the syncfs syscall to sync the filesystem associated
1093to the given filehandle and call the callback with the syncfs result
1094code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1095errno to C<ENOSYS> nevertheless.
1096
863=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1097=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
864 1098
865Sync the data portion of the file specified by C<$offset> and C<$length> 1099Sync the data portion of the file specified by C<$offset> and C<$length>
866to disk (but NOT the metadata), by calling the Linux-specific 1100to disk (but NOT the metadata), by calling the Linux-specific
867sync_file_range call. If sync_file_range is not available or it returns 1101sync_file_range call. If sync_file_range is not available or it returns
… …
878composite request intended to sync directories after directory operations 1112composite request intended to sync directories after directory operations
879(E.g. rename). This might not work on all operating systems or have any 1113(E.g. rename). This might not work on all operating systems or have any
880specific effect, but usually it makes sure that directory changes get 1114specific effect, but usually it makes sure that directory changes get
881written to disc. It works for anything that can be opened for read-only, 1115written to disc. It works for anything that can be opened for read-only,
882not just directories. 1116not just directories.
1117
1118Future versions of this function might fall back to other methods when
1119C<fsync> on the directory fails (such as calling C<sync>).
883 1120
884Passes C<0> when everything went ok, and C<-1> on error. 1121Passes C<0> when everything went ok, and C<-1> on error.
885 1122
886=cut 1123=cut
887 1124
… …
908 }; 1145 };
909 1146
910 $grp 1147 $grp
911} 1148}
912 1149
1150=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1151
1152This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1153scalars (see the C<IO::AIO::mmap> function, although it also works on data
1154scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1155scalar must only be modified in-place while an aio operation is pending on
1156it).
1157
1158It calls the C<msync> function of your OS, if available, with the memory
1159area starting at C<$offset> in the string and ending C<$length> bytes
1160later. If C<$length> is negative, counts from the end, and if C<$length>
1161is C<undef>, then it goes till the end of the string. The flags can be
1162a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
1163C<IO::AIO::MS_SYNC>.
1164
1165=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1166
1167This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1168scalars.
1169
1170It touches (reads or writes) all memory pages in the specified
1171range inside the scalar. All caveats and parameters are the same
1172as for C<aio_msync>, above, except for flags, which must be either
1173C<0> (which reads all pages and ensures they are instantiated) or
1174C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
1175writing an octet from it, which dirties the page).
1176
1177=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1178
1179This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1180scalars.
1181
1182It reads in all the pages of the underlying storage into memory (if any)
1183and locks them, so they are not getting swapped/paged out or removed.
1184
1185If C<$length> is undefined, then the scalar will be locked till the end.
1186
1187On systems that do not implement C<mlock>, this function returns C<-1>
1188and sets errno to C<ENOSYS>.
1189
1190Note that the corresponding C<munlock> is synchronous and is
1191documented under L<MISCELLANEOUS FUNCTIONS>.
1192
1193Example: open a file, mmap and mlock it - both will be undone when
1194C<$data> gets destroyed.
1195
1196 open my $fh, "<", $path or die "$path: $!";
1197 my $data;
1198 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1199 aio_mlock $data; # mlock in background
1200
1201=item aio_mlockall $flags, $callback->($status)
1202
1203Calls the C<mlockall> function with the given C<$flags> (a combination of
1204C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1205
1206On systems that do not implement C<mlockall>, this function returns C<-1>
1207and sets errno to C<ENOSYS>.
1208
1209Note that the corresponding C<munlockall> is synchronous and is
1210documented under L<MISCELLANEOUS FUNCTIONS>.
1211
1212Example: asynchronously lock all current and future pages into memory.
1213
1214 aio_mlockall IO::AIO::MCL_FUTURE;
1215
913=item aio_group $callback->(...) 1216=item aio_group $callback->(...)
914 1217
915This is a very special aio request: Instead of doing something, it is a 1218This is a very special aio request: Instead of doing something, it is a
916container for other aio requests, which is useful if you want to bundle 1219container for other aio requests, which is useful if you want to bundle
917many requests into a single, composite, request with a definite callback 1220many requests into a single, composite, request with a definite callback
… …
966=item cancel $req 1269=item cancel $req
967 1270
968Cancels the request, if possible. Has the effect of skipping execution 1271Cancels the request, if possible. Has the effect of skipping execution
969when entering the B<execute> state and skipping calling the callback when 1272when entering the B<execute> state and skipping calling the callback when
970entering the the B<result> state, but will leave the request otherwise 1273entering the the B<result> state, but will leave the request otherwise
971untouched. That means that requests that currently execute will not be 1274untouched (with the exception of readdir). That means that requests that
972stopped and resources held by the request will not be freed prematurely. 1275currently execute will not be stopped and resources held by the request
1276will not be freed prematurely.
973 1277
974=item cb $req $callback->(...) 1278=item cb $req $callback->(...)
975 1279
976Replace (or simply set) the callback registered to the request. 1280Replace (or simply set) the callback registered to the request.
977 1281
… …
1050 1354
1051=item $grp->cancel_subs 1355=item $grp->cancel_subs
1052 1356
1053Cancel all subrequests and clears any feeder, but not the group request 1357Cancel all subrequests and clears any feeder, but not the group request
1054itself. Useful when you queued a lot of events but got a result early. 1358itself. Useful when you queued a lot of events but got a result early.
1359
1360The group request will finish normally (you cannot add requests to the
1361group).
1055 1362
1056=item $grp->result (...) 1363=item $grp->result (...)
1057 1364
1058Set the result value(s) that will be passed to the group callback when all 1365Set the result value(s) that will be passed to the group callback when all
1059subrequests have finished and set the groups errno to the current value 1366subrequests have finished and set the groups errno to the current value
… …
1128=over 4 1435=over 4
1129 1436
1130=item $fileno = IO::AIO::poll_fileno 1437=item $fileno = IO::AIO::poll_fileno
1131 1438
1132Return the I<request result pipe file descriptor>. This filehandle must be 1439Return the I<request result pipe file descriptor>. This filehandle must be
1133polled for reading by some mechanism outside this module (e.g. Event or 1440polled for reading by some mechanism outside this module (e.g. EV, Glib,
1134select, see below or the SYNOPSIS). If the pipe becomes readable you have 1441select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1135to call C<poll_cb> to check the results. 1442you have to call C<poll_cb> to check the results.
1136 1443
1137See C<poll_cb> for an example. 1444See C<poll_cb> for an example.
1138 1445
1139=item IO::AIO::poll_cb 1446=item IO::AIO::poll_cb
1140 1447
1141Process some outstanding events on the result pipe. You have to call this 1448Process some outstanding events on the result pipe. You have to call
1142regularly. Returns C<0> if all events could be processed, or C<-1> if it 1449this regularly. Returns C<0> if all events could be processed (or there
1143returned earlier for whatever reason. Returns immediately when no events 1450were no events to process), or C<-1> if it returned earlier for whatever
1144are outstanding. The amount of events processed depends on the settings of 1451reason. Returns immediately when no events are outstanding. The amount of
1145C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1452events processed depends on the settings of C<IO::AIO::max_poll_req> and
1453C<IO::AIO::max_poll_time>.
1146 1454
1147If not all requests were processed for whatever reason, the filehandle 1455If not all requests were processed for whatever reason, the filehandle
1148will still be ready when C<poll_cb> returns, so normally you don't have to 1456will still be ready when C<poll_cb> returns, so normally you don't have to
1149do anything special to have it called later. 1457do anything special to have it called later.
1150 1458
1459Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1460ready, it can be beneficial to call this function from loops which submit
1461a lot of requests, to make sure the results get processed when they become
1462available and not just when the loop is finished and the event loop takes
1463over again. This function returns very fast when there are no outstanding
1464requests.
1465
1151Example: Install an Event watcher that automatically calls 1466Example: Install an Event watcher that automatically calls
1152IO::AIO::poll_cb with high priority: 1467IO::AIO::poll_cb with high priority (more examples can be found in the
1468SYNOPSIS section, at the top of this document):
1153 1469
1154 Event->io (fd => IO::AIO::poll_fileno, 1470 Event->io (fd => IO::AIO::poll_fileno,
1155 poll => 'r', async => 1, 1471 poll => 'r', async => 1,
1156 cb => \&IO::AIO::poll_cb); 1472 cb => \&IO::AIO::poll_cb);
1473
1474=item IO::AIO::poll_wait
1475
1476If there are any outstanding requests and none of them in the result
1477phase, wait till the result filehandle becomes ready for reading (simply
1478does a C<select> on the filehandle. This is useful if you want to
1479synchronously wait for some requests to finish).
1480
1481See C<nreqs> for an example.
1482
1483=item IO::AIO::poll
1484
1485Waits until some requests have been handled.
1486
1487Returns the number of requests processed, but is otherwise strictly
1488equivalent to:
1489
1490 IO::AIO::poll_wait, IO::AIO::poll_cb
1491
1492=item IO::AIO::flush
1493
1494Wait till all outstanding AIO requests have been handled.
1495
1496Strictly equivalent to:
1497
1498 IO::AIO::poll_wait, IO::AIO::poll_cb
1499 while IO::AIO::nreqs;
1157 1500
1158=item IO::AIO::max_poll_reqs $nreqs 1501=item IO::AIO::max_poll_reqs $nreqs
1159 1502
1160=item IO::AIO::max_poll_time $seconds 1503=item IO::AIO::max_poll_time $seconds
1161 1504
… …
1186 # use a low priority so other tasks have priority 1529 # use a low priority so other tasks have priority
1187 Event->io (fd => IO::AIO::poll_fileno, 1530 Event->io (fd => IO::AIO::poll_fileno,
1188 poll => 'r', nice => 1, 1531 poll => 'r', nice => 1,
1189 cb => &IO::AIO::poll_cb); 1532 cb => &IO::AIO::poll_cb);
1190 1533
1191=item IO::AIO::poll_wait
1192
1193If there are any outstanding requests and none of them in the result
1194phase, wait till the result filehandle becomes ready for reading (simply
1195does a C<select> on the filehandle. This is useful if you want to
1196synchronously wait for some requests to finish).
1197
1198See C<nreqs> for an example.
1199
1200=item IO::AIO::poll
1201
1202Waits until some requests have been handled.
1203
1204Returns the number of requests processed, but is otherwise strictly
1205equivalent to:
1206
1207 IO::AIO::poll_wait, IO::AIO::poll_cb
1208
1209=item IO::AIO::flush
1210
1211Wait till all outstanding AIO requests have been handled.
1212
1213Strictly equivalent to:
1214
1215 IO::AIO::poll_wait, IO::AIO::poll_cb
1216 while IO::AIO::nreqs;
1217
1218=back 1534=back
1219 1535
1220=head3 CONTROLLING THE NUMBER OF THREADS 1536=head3 CONTROLLING THE NUMBER OF THREADS
1221 1537
1222=over 1538=over
… …
1255 1571
1256Under normal circumstances you don't need to call this function. 1572Under normal circumstances you don't need to call this function.
1257 1573
1258=item IO::AIO::max_idle $nthreads 1574=item IO::AIO::max_idle $nthreads
1259 1575
1260Limit the number of threads (default: 4) that are allowed to idle (i.e., 1576Limit the number of threads (default: 4) that are allowed to idle
1261threads that did not get a request to process within 10 seconds). That 1577(i.e., threads that did not get a request to process within the idle
1262means if a thread becomes idle while C<$nthreads> other threads are also 1578timeout (default: 10 seconds). That means if a thread becomes idle while
1263idle, it will free its resources and exit. 1579C<$nthreads> other threads are also idle, it will free its resources and
1580exit.
1264 1581
1265This is useful when you allow a large number of threads (e.g. 100 or 1000) 1582This is useful when you allow a large number of threads (e.g. 100 or 1000)
1266to allow for extremely high load situations, but want to free resources 1583to allow for extremely high load situations, but want to free resources
1267under normal circumstances (1000 threads can easily consume 30MB of RAM). 1584under normal circumstances (1000 threads can easily consume 30MB of RAM).
1268 1585
1269The default is probably ok in most situations, especially if thread 1586The default is probably ok in most situations, especially if thread
1270creation is fast. If thread creation is very slow on your system you might 1587creation is fast. If thread creation is very slow on your system you might
1271want to use larger values. 1588want to use larger values.
1272 1589
1590=item IO::AIO::idle_timeout $seconds
1591
1592Sets the minimum idle timeout (default 10) after which worker threads are
1593allowed to exit. SEe C<IO::AIO::max_idle>.
1594
1273=item IO::AIO::max_outstanding $maxreqs 1595=item IO::AIO::max_outstanding $maxreqs
1596
1597Sets the maximum number of outstanding requests to C<$nreqs>. If
1598you do queue up more than this number of requests, the next call to
1599C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1600C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1601longer exceeded.
1602
1603In other words, this setting does not enforce a queue limit, but can be
1604used to make poll functions block if the limit is exceeded.
1274 1605
1275This is a very bad function to use in interactive programs because it 1606This is a very bad function to use in interactive programs because it
1276blocks, and a bad way to reduce concurrency because it is inexact: Better 1607blocks, and a bad way to reduce concurrency because it is inexact: Better
1277use an C<aio_group> together with a feed callback. 1608use an C<aio_group> together with a feed callback.
1278 1609
1279Sets the maximum number of outstanding requests to C<$nreqs>. If you 1610It's main use is in scripts without an event loop - when you want to stat
1280do queue up more than this number of requests, the next call to the 1611a lot of files, you can write somehting like this:
1281C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1282function will block until the limit is no longer exceeded.
1283 1612
1284The default value is very large, so there is no practical limit on the 1613 IO::AIO::max_outstanding 32;
1285number of outstanding requests.
1286 1614
1287You can still queue as many requests as you want. Therefore, 1615 for my $path (...) {
1288C<max_outstanding> is mainly useful in simple scripts (with low values) or 1616 aio_stat $path , ...;
1289as a stop gap to shield against fatal memory overflow (with large values). 1617 IO::AIO::poll_cb;
1618 }
1619
1620 IO::AIO::flush;
1621
1622The call to C<poll_cb> inside the loop will normally return instantly, but
1623as soon as more thna C<32> reqeusts are in-flight, it will block until
1624some requests have been handled. This keeps the loop from pushing a large
1625number of C<aio_stat> requests onto the queue.
1626
1627The default value for C<max_outstanding> is very large, so there is no
1628practical limit on the number of outstanding requests.
1290 1629
1291=back 1630=back
1292 1631
1293=head3 STATISTICAL INFORMATION 1632=head3 STATISTICAL INFORMATION
1294 1633
… …
1314Returns the number of requests currently in the pending state (executed, 1653Returns the number of requests currently in the pending state (executed,
1315but not yet processed by poll_cb). 1654but not yet processed by poll_cb).
1316 1655
1317=back 1656=back
1318 1657
1658=head3 MISCELLANEOUS FUNCTIONS
1659
1660IO::AIO implements some functions that might be useful, but are not
1661asynchronous.
1662
1663=over 4
1664
1665=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1666
1667Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1668but is blocking (this makes most sense if you know the input data is
1669likely cached already and the output filehandle is set to non-blocking
1670operations).
1671
1672Returns the number of bytes copied, or C<-1> on error.
1673
1674=item IO::AIO::fadvise $fh, $offset, $len, $advice
1675
1676Simply calls the C<posix_fadvise> function (see its
1677manpage for details). The following advice constants are
1678avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1679C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1680C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1681
1682On systems that do not implement C<posix_fadvise>, this function returns
1683ENOSYS, otherwise the return value of C<posix_fadvise>.
1684
1685=item IO::AIO::madvise $scalar, $offset, $len, $advice
1686
1687Simply calls the C<posix_madvise> function (see its
1688manpage for details). The following advice constants are
1689avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1690C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1691
1692On systems that do not implement C<posix_madvise>, this function returns
1693ENOSYS, otherwise the return value of C<posix_madvise>.
1694
1695=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1696
1697Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1698$scalar (see its manpage for details). The following protect
1699constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1700C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1701
1702On systems that do not implement C<mprotect>, this function returns
1703ENOSYS, otherwise the return value of C<mprotect>.
1704
1705=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1706
1707Memory-maps a file (or anonymous memory range) and attaches it to the
1708given C<$scalar>, which will act like a string scalar.
1709
1710The only operations allowed on the scalar are C<substr>/C<vec> that don't
1711change the string length, and most read-only operations such as copying it
1712or searching it with regexes and so on.
1713
1714Anything else is unsafe and will, at best, result in memory leaks.
1715
1716The memory map associated with the C<$scalar> is automatically removed
1717when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
1718C<IO::AIO::munmap> functions are called.
1719
1720This calls the C<mmap>(2) function internally. See your system's manual
1721page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1722
1723The C<$length> must be larger than zero and smaller than the actual
1724filesize.
1725
1726C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1727C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1728
1729C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
1730C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
1731not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
1732(which is set to C<MAP_ANON> if your system only provides this
1733constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
1734C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1735C<IO::AIO::MAP_NONBLOCK>
1736
1737If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1738
1739C<$offset> is the offset from the start of the file - it generally must be
1740a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1741
1742Example:
1743
1744 use Digest::MD5;
1745 use IO::AIO;
1746
1747 open my $fh, "<verybigfile"
1748 or die "$!";
1749
1750 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1751 or die "verybigfile: $!";
1752
1753 my $fast_md5 = md5 $data;
1754
1755=item IO::AIO::munmap $scalar
1756
1757Removes a previous mmap and undefines the C<$scalar>.
1758
1759=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1760
1761Calls the C<munlock> function, undoing the effects of a previous
1762C<aio_mlock> call (see its description for details).
1763
1764=item IO::AIO::munlockall
1765
1766Calls the C<munlockall> function.
1767
1768On systems that do not implement C<munlockall>, this function returns
1769ENOSYS, otherwise the return value of C<munlockall>.
1770
1771=back
1772
1319=cut 1773=cut
1320 1774
1321min_parallel 8; 1775min_parallel 8;
1322 1776
1323END { flush } 1777END { flush }
1324 1778
13251; 17791;
1326 1780
1781=head1 EVENT LOOP INTEGRATION
1782
1783It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
1784automatically into many event loops:
1785
1786 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1787 use AnyEvent::AIO;
1788
1789You can also integrate IO::AIO manually into many event loops, here are
1790some examples of how to do this:
1791
1792 # EV integration
1793 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1794
1795 # Event integration
1796 Event->io (fd => IO::AIO::poll_fileno,
1797 poll => 'r',
1798 cb => \&IO::AIO::poll_cb);
1799
1800 # Glib/Gtk2 integration
1801 add_watch Glib::IO IO::AIO::poll_fileno,
1802 in => sub { IO::AIO::poll_cb; 1 };
1803
1804 # Tk integration
1805 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1806 readable => \&IO::AIO::poll_cb);
1807
1808 # Danga::Socket integration
1809 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1810 \&IO::AIO::poll_cb);
1811
1327=head2 FORK BEHAVIOUR 1812=head2 FORK BEHAVIOUR
1328 1813
1329This module should do "the right thing" when the process using it forks: 1814Usage of pthreads in a program changes the semantics of fork
1815considerably. Specifically, only async-safe functions can be called after
1816fork. Perl doesn't know about this, so in general, you cannot call fork
1817with defined behaviour in perl if pthreads are involved. IO::AIO uses
1818pthreads, so this applies, but many other extensions and (for inexplicable
1819reasons) perl itself often is linked against pthreads, so this limitation
1820applies to quite a lot of perls.
1330 1821
1331Before the fork, IO::AIO enters a quiescent state where no requests 1822This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1332can be added in other threads and no results will be processed. After 1823only works in the process that loaded it. Forking is fully supported, but
1333the fork the parent simply leaves the quiescent state and continues 1824using IO::AIO in the child is not.
1334request/result processing, while the child frees the request/result queue
1335(so that the requests started before the fork will only be handled in the
1336parent). Threads will be started on demand until the limit set in the
1337parent process has been reached again.
1338 1825
1339In short: the parent will, after a short pause, continue as if fork had 1826You might get around by not I<using> IO::AIO before (or after)
1340not been called, while the child will act as if IO::AIO has not been used 1827forking. You could also try to call the L<IO::AIO::reinit> function in the
1341yet. 1828child:
1829
1830=over 4
1831
1832=item IO::AIO::reinit
1833
1834Abondons all current requests and I/O threads and simply reinitialises all
1835data structures. This is not an operation suppported by any standards, but
1836happens to work on GNU/Linux and some newer BSD systems.
1837
1838The only reasonable use for this function is to call it after forking, if
1839C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
1840the process will result in undefined behaviour. Calling it at any time
1841will also result in any undefined (by POSIX) behaviour.
1842
1843=back
1342 1844
1343=head2 MEMORY USAGE 1845=head2 MEMORY USAGE
1344 1846
1345Per-request usage: 1847Per-request usage:
1346 1848

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