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Revision 1.219 by root, Tue Mar 27 18:54:45 2012 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 = '3.23'; 173 our $VERSION = '4.12';
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 aio_readdirx 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
185 aio_wd);
207 186
208 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210 min_parallel max_parallel max_idle 189 min_parallel max_parallel max_idle idle_timeout
211 nreqs nready npending nthreads 190 nreqs nready npending nthreads
212 max_poll_time max_poll_reqs); 191 max_poll_time max_poll_reqs
192 sendfile fadvise madvise
193 mmap munmap munlock munlockall);
213 194
214 push @AIO_REQ, qw(aio_busy); # not exported 195 push @AIO_REQ, qw(aio_busy); # not exported
215 196
216 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 197 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217 198
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219 XSLoader::load ("IO::AIO", $VERSION); 200 XSLoader::load ("IO::AIO", $VERSION);
220} 201}
221 202
222=head1 FUNCTIONS 203=head1 FUNCTIONS
223 204
224=head2 AIO REQUEST FUNCTIONS 205=head2 QUICK OVERVIEW
206
207This section simply lists the prototypes of the most important functions
208for quick reference. See the following sections for function-by-function
209documentation.
210
211 aio_wd $pathname, $callback->($wd)
212 aio_open $pathname, $flags, $mode, $callback->($fh)
213 aio_close $fh, $callback->($status)
214 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217 aio_readahead $fh,$offset,$length, $callback->($retval)
218 aio_stat $fh_or_path, $callback->($status)
219 aio_lstat $fh, $callback->($status)
220 aio_statvfs $fh_or_path, $callback->($statvfs)
221 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
223 aio_truncate $fh_or_path, $offset, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status)
225 aio_unlink $pathname, $callback->($status)
226 aio_mknod $pathname, $mode, $dev, $callback->($status)
227 aio_link $srcpath, $dstpath, $callback->($status)
228 aio_symlink $srcpath, $dstpath, $callback->($status)
229 aio_readlink $pathname, $callback->($link)
230 aio_realpath $pathname, $callback->($link)
231 aio_rename $srcpath, $dstpath, $callback->($status)
232 aio_mkdir $pathname, $mode, $callback->($status)
233 aio_rmdir $pathname, $callback->($status)
234 aio_readdir $pathname, $callback->($entries)
235 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
238 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
239 aio_load $pathname, $data, $callback->($status)
240 aio_copy $srcpath, $dstpath, $callback->($status)
241 aio_move $srcpath, $dstpath, $callback->($status)
242 aio_rmtree $pathname, $callback->($status)
243 aio_sync $callback->($status)
244 aio_syncfs $fh, $callback->($status)
245 aio_fsync $fh, $callback->($status)
246 aio_fdatasync $fh, $callback->($status)
247 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248 aio_pathsync $pathname, $callback->($status)
249 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
250 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252 aio_mlockall $flags, $callback->($status)
253 aio_group $callback->(...)
254 aio_nop $callback->()
255
256 $prev_pri = aioreq_pri [$pri]
257 aioreq_nice $pri_adjust
258
259 IO::AIO::poll_wait
260 IO::AIO::poll_cb
261 IO::AIO::poll
262 IO::AIO::flush
263 IO::AIO::max_poll_reqs $nreqs
264 IO::AIO::max_poll_time $seconds
265 IO::AIO::min_parallel $nthreads
266 IO::AIO::max_parallel $nthreads
267 IO::AIO::max_idle $nthreads
268 IO::AIO::idle_timeout $seconds
269 IO::AIO::max_outstanding $maxreqs
270 IO::AIO::nreqs
271 IO::AIO::nready
272 IO::AIO::npending
273
274 IO::AIO::sendfile $ofh, $ifh, $offset, $count
275 IO::AIO::fadvise $fh, $offset, $len, $advice
276 IO::AIO::madvise $scalar, $offset, $length, $advice
277 IO::AIO::mprotect $scalar, $offset, $length, $protect
278 IO::AIO::munlock $scalar, $offset = 0, $length = undef
279 IO::AIO::munlockall
280
281=head2 API NOTES
225 282
226All the C<aio_*> calls are more or less thin wrappers around the syscall 283All the C<aio_*> calls are more or less thin wrappers around the syscall
227with the same name (sans C<aio_>). The arguments are similar or identical, 284with the same name (sans C<aio_>). The arguments are similar or identical,
228and they all accept an additional (and optional) C<$callback> argument 285and they all accept an additional (and optional) C<$callback> argument
229which must be a code reference. This code reference will get called with 286which must be a code reference. This code reference will be called after
230the syscall return code (e.g. most syscalls return C<-1> on error, unlike 287the syscall has been executed in an asynchronous fashion. The results
231perl, which usually delivers "false") as its sole argument after the given 288of the request will be passed as arguments to the callback (and, if an
232syscall has been executed asynchronously. 289error occured, in C<$!>) - for most requests the syscall return code (e.g.
290most syscalls return C<-1> on error, unlike perl, which usually delivers
291"false").
292
293Some requests (such as C<aio_readdir>) pass the actual results and
294communicate failures by passing C<undef>.
233 295
234All functions expecting a filehandle keep a copy of the filehandle 296All functions expecting a filehandle keep a copy of the filehandle
235internally until the request has finished. 297internally until the request has finished.
236 298
237All functions return request objects of type L<IO::AIO::REQ> that allow 299All functions return request objects of type L<IO::AIO::REQ> that allow
238further manipulation of those requests while they are in-flight. 300further manipulation of those requests while they are in-flight.
239 301
240The pathnames you pass to these routines I<must> be absolute and 302The pathnames you pass to these routines I<should> be absolute. The
241encoded as octets. The reason for the former is that at the time the 303reason for this is that at the time the request is being executed, the
242request is being executed, the current working directory could have 304current working directory could have changed. Alternatively, you can
243changed. Alternatively, you can make sure that you never change the 305make sure that you never change the current working directory anywhere
244current working directory anywhere in the program and then use relative 306in the program and then use relative paths. You can also take advantage
245paths. 307of IO::AIOs working directory abstraction, that lets you specify paths
308relative to some previously-opened "working directory object" - see the
309description of the C<IO::AIO::WD> class later in this document.
246 310
247To encode pathnames as octets, either make sure you either: a) always pass 311To encode pathnames as octets, either make sure you either: a) always pass
248in filenames you got from outside (command line, readdir etc.) without 312in filenames you got from outside (command line, readdir etc.) without
249tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 313tinkering, b) are in your native filesystem encoding, c) use the Encode
250your pathnames to the locale (or other) encoding in effect in the user 314module and encode your pathnames to the locale (or other) encoding in
251environment, d) use Glib::filename_from_unicode on unicode filenames or e) 315effect in the user environment, d) use Glib::filename_from_unicode on
252use something else to ensure your scalar has the correct contents. 316unicode filenames or e) use something else to ensure your scalar has the
317correct contents.
253 318
254This works, btw. independent of the internal UTF-8 bit, which IO::AIO 319This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255handles correctly whether it is set or not. 320handles correctly whether it is set or not.
321
322=head2 AIO REQUEST FUNCTIONS
256 323
257=over 4 324=over 4
258 325
259=item $prev_pri = aioreq_pri [$pri] 326=item $prev_pri = aioreq_pri [$pri]
260 327
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307by the umask in effect then the request is being executed, so better never 374by the umask in effect then the request is being executed, so better never
308change the umask. 375change the umask.
309 376
310Example: 377Example:
311 378
312 aio_open "/etc/passwd", O_RDONLY, 0, sub { 379 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313 if ($_[0]) { 380 if ($_[0]) {
314 print "open successful, fh is $_[0]\n"; 381 print "open successful, fh is $_[0]\n";
315 ... 382 ...
316 } else { 383 } else {
317 die "open failed: $!\n"; 384 die "open failed: $!\n";
318 } 385 }
319 }; 386 };
320 387
388In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
389C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
390following POSIX and non-POSIX constants are available (missing ones on
391your system are, as usual, C<0>):
392
393C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
394C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
395C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
396
321 397
322=item aio_close $fh, $callback->($status) 398=item aio_close $fh, $callback->($status)
323 399
324Asynchronously close a file and call the callback with the result 400Asynchronously close a file and call the callback with the result
325code. 401code.
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375 451
376Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 452Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377reading at byte offset C<$in_offset>, and starts writing at the current 453reading at byte offset C<$in_offset>, and starts writing at the current
378file offset of C<$out_fh>. Because of that, it is not safe to issue more 454file offset of C<$out_fh>. Because of that, it is not safe to issue more
379than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 455than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380other. 456other. The same C<$in_fh> works fine though, as this function does not
457move or use the file offset of C<$in_fh>.
381 458
459Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
460are written, and there is no way to find out how many more bytes have been
461read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
462number of bytes written to C<$out_fh>. Only if the result value equals
463C<$length> one can assume that C<$length> bytes have been read.
464
465Unlike with other C<aio_> functions, it makes a lot of sense to use
466C<aio_sendfile> on non-blocking sockets, as long as one end (typically
467the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
468the socket I/O will be non-blocking. Note, however, that you can run
469into a trap where C<aio_sendfile> reads some data with readahead, then
470fails to write all data, and when the socket is ready the next time, the
471data in the cache is already lost, forcing C<aio_sendfile> to again hit
472the disk. Explicit C<aio_read> + C<aio_write> let's you better control
473resource usage.
474
382This call tries to make use of a native C<sendfile> syscall to provide 475This call tries to make use of a native C<sendfile>-like syscall to
383zero-copy operation. For this to work, C<$out_fh> should refer to a 476provide zero-copy operation. For this to work, C<$out_fh> should refer to
384socket, and C<$in_fh> should refer to mmap'able file. 477a socket, and C<$in_fh> should refer to an mmap'able file.
385 478
386If the native sendfile call fails or is not implemented, it will be 479If a native sendfile cannot be found or it fails with C<ENOSYS>,
387emulated, so you can call C<aio_sendfile> on any type of filehandle 480C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
481C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
388regardless of the limitations of the operating system. 482type of filehandle regardless of the limitations of the operating system.
389 483
390Please note, however, that C<aio_sendfile> can read more bytes from 484As native sendfile syscalls (as practically any non-POSIX interface hacked
391C<$in_fh> than are written, and there is no way to find out how many 485together in a hurry to improve benchmark numbers) tend to be rather buggy
392bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 486on many systems, this implementation tries to work around some known bugs
393provides the number of bytes written to C<$out_fh>. Only if the result 487in Linux and FreeBSD kernels (probably others, too), but that might fail,
394value equals C<$length> one can assume that C<$length> bytes have been 488so you really really should check the return value of C<aio_sendfile> -
395read. 489fewre bytes than expected might have been transferred.
396 490
397 491
398=item aio_readahead $fh,$offset,$length, $callback->($retval) 492=item aio_readahead $fh,$offset,$length, $callback->($retval)
399 493
400C<aio_readahead> populates the page cache with data from a file so that 494C<aio_readahead> populates the page cache with data from a file so that
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423 517
424Currently, the stats are always 64-bit-stats, i.e. instead of returning an 518Currently, the stats are always 64-bit-stats, i.e. instead of returning an
425error when stat'ing a large file, the results will be silently truncated 519error when stat'ing a large file, the results will be silently truncated
426unless perl itself is compiled with large file support. 520unless perl itself is compiled with large file support.
427 521
522To help interpret the mode and dev/rdev stat values, IO::AIO offers the
523following constants and functions (if not implemented, the constants will
524be C<0> and the functions will either C<croak> or fall back on traditional
525behaviour).
526
527C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
528C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
529C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
530
428Example: Print the length of F</etc/passwd>: 531Example: Print the length of F</etc/passwd>:
429 532
430 aio_stat "/etc/passwd", sub { 533 aio_stat "/etc/passwd", sub {
431 $_[0] and die "stat failed: $!"; 534 $_[0] and die "stat failed: $!";
432 print "size is ", -s _, "\n"; 535 print "size is ", -s _, "\n";
433 }; 536 };
434 537
435 538
539=item aio_statvfs $fh_or_path, $callback->($statvfs)
540
541Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
542whether a file handle or path was passed.
543
544On success, the callback is passed a hash reference with the following
545members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
546C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
547is passed.
548
549The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
550C<ST_NOSUID>.
551
552The following non-POSIX IO::AIO::ST_* flag masks are defined to
553their correct value when available, or to C<0> on systems that do
554not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
555C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
556C<ST_NODIRATIME> and C<ST_RELATIME>.
557
558Example: stat C</wd> and dump out the data if successful.
559
560 aio_statvfs "/wd", sub {
561 my $f = $_[0]
562 or die "statvfs: $!";
563
564 use Data::Dumper;
565 say Dumper $f;
566 };
567
568 # result:
569 {
570 bsize => 1024,
571 bfree => 4333064312,
572 blocks => 10253828096,
573 files => 2050765568,
574 flag => 4096,
575 favail => 2042092649,
576 bavail => 4333064312,
577 ffree => 2042092649,
578 namemax => 255,
579 frsize => 1024,
580 fsid => 1810
581 }
582
583
436=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 584=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437 585
438Works like perl's C<utime> function (including the special case of $atime 586Works like perl's C<utime> function (including the special case of $atime
439and $mtime being undef). Fractional times are supported if the underlying 587and $mtime being undef). Fractional times are supported if the underlying
440syscalls support them. 588syscalls support them.
… …
478 626
479Asynchronously unlink (delete) a file and call the callback with the 627Asynchronously unlink (delete) a file and call the callback with the
480result code. 628result code.
481 629
482 630
483=item aio_mknod $path, $mode, $dev, $callback->($status) 631=item aio_mknod $pathname, $mode, $dev, $callback->($status)
484 632
485[EXPERIMENTAL] 633[EXPERIMENTAL]
486 634
487Asynchronously create a device node (or fifo). See mknod(2). 635Asynchronously create a device node (or fifo). See mknod(2).
488 636
489The only (POSIX-) portable way of calling this function is: 637The only (POSIX-) portable way of calling this function is:
490 638
491 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 639 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492 640
641See C<aio_stat> for info about some potentially helpful extra constants
642and functions.
493 643
494=item aio_link $srcpath, $dstpath, $callback->($status) 644=item aio_link $srcpath, $dstpath, $callback->($status)
495 645
496Asynchronously create a new link to the existing object at C<$srcpath> at 646Asynchronously create a new link to the existing object at C<$srcpath> at
497the path C<$dstpath> and call the callback with the result code. 647the path C<$dstpath> and call the callback with the result code.
… …
501 651
502Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 652Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
503the path C<$dstpath> and call the callback with the result code. 653the path C<$dstpath> and call the callback with the result code.
504 654
505 655
506=item aio_readlink $path, $callback->($link) 656=item aio_readlink $pathname, $callback->($link)
507 657
508Asynchronously read the symlink specified by C<$path> and pass it to 658Asynchronously read the symlink specified by C<$path> and pass it to
509the callback. If an error occurs, nothing or undef gets passed to the 659the callback. If an error occurs, nothing or undef gets passed to the
510callback. 660callback.
511 661
512 662
663=item aio_realpath $pathname, $callback->($path)
664
665Asynchronously make the path absolute and resolve any symlinks in
666C<$path>. The resulting path only consists of directories (Same as
667L<Cwd::realpath>).
668
669This request can be used to get the absolute path of the current working
670directory by passing it a path of F<.> (a single dot).
671
672
513=item aio_rename $srcpath, $dstpath, $callback->($status) 673=item aio_rename $srcpath, $dstpath, $callback->($status)
514 674
515Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 675Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
516rename(2) and call the callback with the result code. 676rename(2) and call the callback with the result code.
517 677
… …
539array-ref with the filenames. 699array-ref with the filenames.
540 700
541 701
542=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) 702=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
543 703
544Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune 704Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
545behaviour and output format. In case of an error, C<$entries> will be 705tune behaviour and output format. In case of an error, C<$entries> will be
546C<undef>. 706C<undef>.
547 707
548The flags are a combination of the following constants, ORed together (the 708The flags are a combination of the following constants, ORed together (the
549flags will also be passed to the callback, possibly modified): 709flags will also be passed to the callback, possibly modified):
550 710
551=over 4 711=over 4
552 712
553=item IO::AIO::READDIR_DENTS 713=item IO::AIO::READDIR_DENTS
554 714
555When this flag is off, then the callback gets an arrayref with of names 715When this flag is off, then the callback gets an arrayref consisting of
556only (as with C<aio_readdir>), otherwise it gets an arrayref with 716names only (as with C<aio_readdir>), otherwise it gets an arrayref with
557C<[$name, $type, $inode]> arrayrefs, each describing a single directory 717C<[$name, $type, $inode]> arrayrefs, each describing a single directory
558entry in more detail. 718entry in more detail.
559 719
560C<$name> is the name of the entry. 720C<$name> is the name of the entry.
561 721
… …
574systems that do not deliver the inode information. 734systems that do not deliver the inode information.
575 735
576=item IO::AIO::READDIR_DIRS_FIRST 736=item IO::AIO::READDIR_DIRS_FIRST
577 737
578When this flag is set, then the names will be returned in an order where 738When this flag is set, then the names will be returned in an order where
579likely directories come first. This is useful when you need to quickly 739likely directories come first, in optimal stat order. This is useful when
580find directories, or you want to find all directories while avoiding to 740you need to quickly find directories, or you want to find all directories
581stat() each entry. 741while avoiding to stat() each entry.
582 742
583If the system returns type information in readdir, then this is used 743If the system returns type information in readdir, then this is used
584to find directories directly. Otherwise, likely directories are files 744to find directories directly. Otherwise, likely directories are names
585beginning with ".", or otherwise files with no dots, of which files with 745beginning with ".", or otherwise names with no dots, of which names with
586short names are tried first. 746short names are tried first.
587 747
588=item IO::AIO::READDIR_STAT_ORDER 748=item IO::AIO::READDIR_STAT_ORDER
589 749
590When this flag is set, then the names will be returned in an order 750When this flag is set, then the names will be returned in an order
… …
597 757
598=item IO::AIO::READDIR_FOUND_UNKNOWN 758=item IO::AIO::READDIR_FOUND_UNKNOWN
599 759
600This flag should not be set when calling C<aio_readdirx>. Instead, it 760This flag should not be set when calling C<aio_readdirx>. Instead, it
601is being set by C<aio_readdirx>, when any of the C<$type>'s found were 761is being set by C<aio_readdirx>, when any of the C<$type>'s found were
602C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all 762C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
603C<$type>'s are known, which can be used to speed up some algorithms. 763C<$type>'s are known, which can be used to speed up some algorithms.
604 764
605=back 765=back
606 766
607 767
608=item aio_load $path, $data, $callback->($status) 768=item aio_load $pathname, $data, $callback->($status)
609 769
610This is a composite request that tries to fully load the given file into 770This is a composite request that tries to fully load the given file into
611memory. Status is the same as with aio_read. 771memory. Status is the same as with aio_read.
612 772
613=cut 773=cut
… …
635 795
636=item aio_copy $srcpath, $dstpath, $callback->($status) 796=item aio_copy $srcpath, $dstpath, $callback->($status)
637 797
638Try to copy the I<file> (directories not supported as either source or 798Try to copy the I<file> (directories not supported as either source or
639destination) from C<$srcpath> to C<$dstpath> and call the callback with 799destination) from C<$srcpath> to C<$dstpath> and call the callback with
640the C<0> (error) or C<-1> ok. 800a status of C<0> (ok) or C<-1> (error, see C<$!>).
641 801
642This is a composite request that creates the destination file with 802This is a composite request that creates the destination file with
643mode 0200 and copies the contents of the source file into it using 803mode 0200 and copies the contents of the source file into it using
644C<aio_sendfile>, followed by restoring atime, mtime, access mode and 804C<aio_sendfile>, followed by restoring atime, mtime, access mode and
645uid/gid, in that order. 805uid/gid, in that order.
… …
657 my $grp = aio_group $cb; 817 my $grp = aio_group $cb;
658 818
659 aioreq_pri $pri; 819 aioreq_pri $pri;
660 add $grp aio_open $src, O_RDONLY, 0, sub { 820 add $grp aio_open $src, O_RDONLY, 0, sub {
661 if (my $src_fh = $_[0]) { 821 if (my $src_fh = $_[0]) {
662 my @stat = stat $src_fh; # hmm, might bock over nfs? 822 my @stat = stat $src_fh; # hmm, might block over nfs?
663 823
664 aioreq_pri $pri; 824 aioreq_pri $pri;
665 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { 825 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
666 if (my $dst_fh = $_[0]) { 826 if (my $dst_fh = $_[0]) {
667 aioreq_pri $pri; 827 aioreq_pri $pri;
… …
714 874
715=item aio_move $srcpath, $dstpath, $callback->($status) 875=item aio_move $srcpath, $dstpath, $callback->($status)
716 876
717Try to move the I<file> (directories not supported as either source or 877Try to move the I<file> (directories not supported as either source or
718destination) from C<$srcpath> to C<$dstpath> and call the callback with 878destination) from C<$srcpath> to C<$dstpath> and call the callback with
719the C<0> (error) or C<-1> ok. 879a status of C<0> (ok) or C<-1> (error, see C<$!>).
720 880
721This is a composite request that tries to rename(2) the file first; if 881This is a composite request that tries to rename(2) the file first; if
722rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if 882rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
723that is successful, unlinks the C<$srcpath>. 883that is successful, unlinks the C<$srcpath>.
724 884
… …
735 if ($_[0] && $! == EXDEV) { 895 if ($_[0] && $! == EXDEV) {
736 aioreq_pri $pri; 896 aioreq_pri $pri;
737 add $grp aio_copy $src, $dst, sub { 897 add $grp aio_copy $src, $dst, sub {
738 $grp->result ($_[0]); 898 $grp->result ($_[0]);
739 899
740 if (!$_[0]) { 900 unless ($_[0]) {
741 aioreq_pri $pri; 901 aioreq_pri $pri;
742 add $grp aio_unlink $src; 902 add $grp aio_unlink $src;
743 } 903 }
744 }; 904 };
745 } else { 905 } else {
… …
748 }; 908 };
749 909
750 $grp 910 $grp
751} 911}
752 912
753=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 913=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
754 914
755Scans a directory (similar to C<aio_readdir>) but additionally tries to 915Scans a directory (similar to C<aio_readdir>) but additionally tries to
756efficiently separate the entries of directory C<$path> into two sets of 916efficiently separate the entries of directory C<$path> into two sets of
757names, directories you can recurse into (directories), and ones you cannot 917names, directories you can recurse into (directories), and ones you cannot
758recurse into (everything else, including symlinks to directories). 918recurse into (everything else, including symlinks to directories).
… …
789Then entries will be sorted into likely directories a non-initial dot 949Then entries will be sorted into likely directories a non-initial dot
790currently) and likely non-directories (see C<aio_readdirx>). Then every 950currently) and likely non-directories (see C<aio_readdirx>). Then every
791entry plus an appended C</.> will be C<stat>'ed, likely directories first, 951entry plus an appended C</.> will be C<stat>'ed, likely directories first,
792in order of their inode numbers. If that succeeds, it assumes that the 952in order of their inode numbers. If that succeeds, it assumes that the
793entry is a directory or a symlink to directory (which will be checked 953entry is a directory or a symlink to directory (which will be checked
794seperately). This is often faster than stat'ing the entry itself because 954separately). This is often faster than stat'ing the entry itself because
795filesystems might detect the type of the entry without reading the inode 955filesystems might detect the type of the entry without reading the inode
796data (e.g. ext2fs filetype feature), even on systems that cannot return 956data (e.g. ext2fs filetype feature), even on systems that cannot return
797the filetype information on readdir. 957the filetype information on readdir.
798 958
799If the known number of directories (link count - 2) has been reached, the 959If the known number of directories (link count - 2) has been reached, the
… …
815 975
816 my $grp = aio_group $cb; 976 my $grp = aio_group $cb;
817 977
818 $maxreq = 4 if $maxreq <= 0; 978 $maxreq = 4 if $maxreq <= 0;
819 979
820 # stat once 980 # get a wd object
821 aioreq_pri $pri; 981 aioreq_pri $pri;
822 add $grp aio_stat $path, sub { 982 add $grp aio_wd $path, sub {
983 $_[0]
823 return $grp->result () if $_[0]; 984 or return $grp->result ();
824 my $now = time;
825 my $hash1 = join ":", (stat _)[0,1,3,7,9];
826 985
827 # read the directory entries 986 my $wd = [shift, "."];
987
988 # stat once
828 aioreq_pri $pri; 989 aioreq_pri $pri;
829 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { 990 add $grp aio_stat $wd, sub {
830 my $entries = shift
831 or return $grp->result (); 991 return $grp->result () if $_[0];
992 my $now = time;
993 my $hash1 = join ":", (stat _)[0,1,3,7,9];
832 994
833 # stat the dir another time 995 # read the directory entries
834 aioreq_pri $pri; 996 aioreq_pri $pri;
997 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
998 my $entries = shift
999 or return $grp->result ();
1000
1001 # stat the dir another time
1002 aioreq_pri $pri;
835 add $grp aio_stat $path, sub { 1003 add $grp aio_stat $wd, sub {
836 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1004 my $hash2 = join ":", (stat _)[0,1,3,7,9];
837 1005
838 my $ndirs; 1006 my $ndirs;
839 1007
840 # take the slow route if anything looks fishy 1008 # take the slow route if anything looks fishy
841 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1009 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
842 $ndirs = -1; 1010 $ndirs = -1;
843 } else { 1011 } else {
844 # if nlink == 2, we are finished 1012 # if nlink == 2, we are finished
845 # for non-posix-fs's, we rely on nlink < 2 1013 # for non-posix-fs's, we rely on nlink < 2
846 $ndirs = (stat _)[3] - 2 1014 $ndirs = (stat _)[3] - 2
847 or return $grp->result ([], $entries); 1015 or return $grp->result ([], $entries);
848 } 1016 }
849 1017
850 my (@dirs, @nondirs); 1018 my (@dirs, @nondirs);
851 1019
852 my $statgrp = add $grp aio_group sub { 1020 my $statgrp = add $grp aio_group sub {
853 $grp->result (\@dirs, \@nondirs); 1021 $grp->result (\@dirs, \@nondirs);
854 }; 1022 };
855 1023
856 limit $statgrp $maxreq; 1024 limit $statgrp $maxreq;
857 feed $statgrp sub { 1025 feed $statgrp sub {
858 return unless @$entries; 1026 return unless @$entries;
859 my $entry = shift @$entries; 1027 my $entry = shift @$entries;
860 1028
861 aioreq_pri $pri; 1029 aioreq_pri $pri;
1030 $wd->[1] = "$entry/.";
862 add $statgrp aio_stat "$path/$entry/.", sub { 1031 add $statgrp aio_stat $wd, sub {
863 if ($_[0] < 0) { 1032 if ($_[0] < 0) {
864 push @nondirs, $entry; 1033 push @nondirs, $entry;
865 } else { 1034 } else {
866 # need to check for real directory 1035 # need to check for real directory
867 aioreq_pri $pri; 1036 aioreq_pri $pri;
1037 $wd->[1] = $entry;
868 add $statgrp aio_lstat "$path/$entry", sub { 1038 add $statgrp aio_lstat $wd, sub {
869 if (-d _) { 1039 if (-d _) {
870 push @dirs, $entry; 1040 push @dirs, $entry;
871 1041
872 unless (--$ndirs) { 1042 unless (--$ndirs) {
873 push @nondirs, @$entries; 1043 push @nondirs, @$entries;
874 feed $statgrp; 1044 feed $statgrp;
1045 }
1046 } else {
1047 push @nondirs, $entry;
875 } 1048 }
876 } else {
877 push @nondirs, $entry;
878 } 1049 }
879 } 1050 }
880 } 1051 };
881 }; 1052 };
882 }; 1053 };
883 }; 1054 };
884 }; 1055 };
885 }; 1056 };
886 1057
887 $grp 1058 $grp
888} 1059}
889 1060
890=item aio_rmtree $path, $callback->($status) 1061=item aio_rmtree $pathname, $callback->($status)
891 1062
892Delete a directory tree starting (and including) C<$path>, return the 1063Delete a directory tree starting (and including) C<$path>, return the
893status of the final C<rmdir> only. This is a composite request that 1064status of the final C<rmdir> only. This is a composite request that
894uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1065uses C<aio_scandir> to recurse into and rmdir directories, and unlink
895everything else. 1066everything else.
… …
937callback with the fdatasync result code. 1108callback with the fdatasync result code.
938 1109
939If this call isn't available because your OS lacks it or it couldn't be 1110If this call isn't available because your OS lacks it or it couldn't be
940detected, it will be emulated by calling C<fsync> instead. 1111detected, it will be emulated by calling C<fsync> instead.
941 1112
1113=item aio_syncfs $fh, $callback->($status)
1114
1115Asynchronously call the syncfs syscall to sync the filesystem associated
1116to the given filehandle and call the callback with the syncfs result
1117code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1118errno to C<ENOSYS> nevertheless.
1119
942=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1120=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
943 1121
944Sync the data portion of the file specified by C<$offset> and C<$length> 1122Sync the data portion of the file specified by C<$offset> and C<$length>
945to disk (but NOT the metadata), by calling the Linux-specific 1123to disk (but NOT the metadata), by calling the Linux-specific
946sync_file_range call. If sync_file_range is not available or it returns 1124sync_file_range call. If sync_file_range is not available or it returns
… …
949C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, 1127C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
950C<IO::AIO::SYNC_FILE_RANGE_WRITE> and 1128C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
951C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range 1129C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
952manpage for details. 1130manpage for details.
953 1131
954=item aio_pathsync $path, $callback->($status) 1132=item aio_pathsync $pathname, $callback->($status)
955 1133
956This request tries to open, fsync and close the given path. This is a 1134This request tries to open, fsync and close the given path. This is a
957composite request intended to sync directories after directory operations 1135composite request intended to sync directories after directory operations
958(E.g. rename). This might not work on all operating systems or have any 1136(E.g. rename). This might not work on all operating systems or have any
959specific effect, but usually it makes sure that directory changes get 1137specific effect, but usually it makes sure that directory changes get
960written to disc. It works for anything that can be opened for read-only, 1138written to disc. It works for anything that can be opened for read-only,
961not just directories. 1139not just directories.
1140
1141Future versions of this function might fall back to other methods when
1142C<fsync> on the directory fails (such as calling C<sync>).
962 1143
963Passes C<0> when everything went ok, and C<-1> on error. 1144Passes C<0> when everything went ok, and C<-1> on error.
964 1145
965=cut 1146=cut
966 1147
… …
987 }; 1168 };
988 1169
989 $grp 1170 $grp
990} 1171}
991 1172
1173=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1174
1175This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1176scalars (see the C<IO::AIO::mmap> function, although it also works on data
1177scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1178scalar must only be modified in-place while an aio operation is pending on
1179it).
1180
1181It calls the C<msync> function of your OS, if available, with the memory
1182area starting at C<$offset> in the string and ending C<$length> bytes
1183later. If C<$length> is negative, counts from the end, and if C<$length>
1184is C<undef>, then it goes till the end of the string. The flags can be
1185a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
1186C<IO::AIO::MS_SYNC>.
1187
1188=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1189
1190This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1191scalars.
1192
1193It touches (reads or writes) all memory pages in the specified
1194range inside the scalar. All caveats and parameters are the same
1195as for C<aio_msync>, above, except for flags, which must be either
1196C<0> (which reads all pages and ensures they are instantiated) or
1197C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
1198writing an octet from it, which dirties the page).
1199
1200=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1201
1202This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1203scalars.
1204
1205It reads in all the pages of the underlying storage into memory (if any)
1206and locks them, so they are not getting swapped/paged out or removed.
1207
1208If C<$length> is undefined, then the scalar will be locked till the end.
1209
1210On systems that do not implement C<mlock>, this function returns C<-1>
1211and sets errno to C<ENOSYS>.
1212
1213Note that the corresponding C<munlock> is synchronous and is
1214documented under L<MISCELLANEOUS FUNCTIONS>.
1215
1216Example: open a file, mmap and mlock it - both will be undone when
1217C<$data> gets destroyed.
1218
1219 open my $fh, "<", $path or die "$path: $!";
1220 my $data;
1221 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1222 aio_mlock $data; # mlock in background
1223
1224=item aio_mlockall $flags, $callback->($status)
1225
1226Calls the C<mlockall> function with the given C<$flags> (a combination of
1227C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1228
1229On systems that do not implement C<mlockall>, this function returns C<-1>
1230and sets errno to C<ENOSYS>.
1231
1232Note that the corresponding C<munlockall> is synchronous and is
1233documented under L<MISCELLANEOUS FUNCTIONS>.
1234
1235Example: asynchronously lock all current and future pages into memory.
1236
1237 aio_mlockall IO::AIO::MCL_FUTURE;
1238
992=item aio_group $callback->(...) 1239=item aio_group $callback->(...)
993 1240
994This is a very special aio request: Instead of doing something, it is a 1241This is a very special aio request: Instead of doing something, it is a
995container for other aio requests, which is useful if you want to bundle 1242container for other aio requests, which is useful if you want to bundle
996many requests into a single, composite, request with a definite callback 1243many requests into a single, composite, request with a definite callback
… …
1032like sleep and file handle readable/writable, the overhead this creates is 1279like sleep and file handle readable/writable, the overhead this creates is
1033immense (it blocks a thread for a long time) so do not use this function 1280immense (it blocks a thread for a long time) so do not use this function
1034except to put your application under artificial I/O pressure. 1281except to put your application under artificial I/O pressure.
1035 1282
1036=back 1283=back
1284
1285
1286=head2 IO::AIO::WD - multiple working directories
1287
1288Your process only has one current working directory, which is used by all
1289threads. This makes it hard to use relative paths (some other component
1290could call C<chdir> at any time, and it is hard to control when the path
1291will be used by IO::AIO).
1292
1293One solution for this is to always use absolute paths. This usually works,
1294but can be quite slow (the kernel has to walk the whole path on every
1295access), and can also be a hassle to implement.
1296
1297Newer POSIX systems have a number of functions (openat, fdopendir,
1298futimensat and so on) that make it possible to specify working directories
1299per operation.
1300
1301For portability, and because the clowns who "designed", or shall I write,
1302perpetrated this new interface were obviously half-drunk, this abstraction
1303cannot be perfect, though.
1304
1305IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1306object. This object stores the canonicalised, absolute version of the
1307path, and on systems that allow it, also a directory file descriptor.
1308
1309Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1310or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1311object and a pathname instead (or the IO::AIO::WD object alone, which
1312gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1313IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1314to that IO::AIO::WD object.
1315
1316For example, to get a wd object for F</etc> and then stat F<passwd>
1317inside, you would write:
1318
1319 aio_wd "/etc", sub {
1320 my $etcdir = shift;
1321
1322 # although $etcdir can be undef on error, there is generally no reason
1323 # to check for errors here, as aio_stat will fail with ENOENT
1324 # when $etcdir is undef.
1325
1326 aio_stat [$etcdir, "passwd"], sub {
1327 # yay
1328 };
1329 };
1330
1331That C<aio_wd> is a request and not a normal function shows that creating
1332an IO::AIO::WD object is itself a potentially blocking operation, which is
1333why it is done asynchronously.
1334
1335To stat the directory obtained with C<aio_wd> above, one could write
1336either of the following three request calls:
1337
1338 aio_lstat "/etc" , sub { ... # pathname as normal string
1339 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1340 aio_lstat $wd , sub { ... # shorthand for the previous
1341
1342As with normal pathnames, IO::AIO keeps a copy of the working directory
1343object and the pathname string, so you could write the following without
1344causing any issues due to C<$path> getting reused:
1345
1346 my $path = [$wd, undef];
1347
1348 for my $name (qw(abc def ghi)) {
1349 $path->[1] = $name;
1350 aio_stat $path, sub {
1351 # ...
1352 };
1353 }
1354
1355There are some caveats: when directories get renamed (or deleted), the
1356pathname string doesn't change, so will point to the new directory (or
1357nowhere at all), while the directory fd, if available on the system,
1358will still point to the original directory. Most functions accepting a
1359pathname will use the directory fd on newer systems, and the string on
1360older systems. Some functions (such as realpath) will always rely on the
1361string form of the pathname.
1362
1363So this fucntionality is mainly useful to get some protection against
1364C<chdir>, to easily get an absolute path out of a relative path for future
1365reference, and to speed up doing many operations in the same directory
1366(e.g. when stat'ing all files in a directory).
1367
1368The following functions implement this working directory abstraction:
1369
1370=over 4
1371
1372=item aio_wd $pathname, $callback->($wd)
1373
1374Asynchonously canonicalise the given pathname and convert it to an
1375IO::AIO::WD object representing it. If possible and supported on the
1376system, also open a directory fd to speed up pathname resolution relative
1377to this working directory.
1378
1379If something goes wrong, then C<undef> is passwd to the callback instead
1380of a working directory object and C<$!> is set appropriately. Since
1381passing C<undef> as working directory component of a pathname fails the
1382request with C<ENOENT>, there is often no need for error checking in the
1383C<aio_wd> callback, as future requests using the value will fail in the
1384expected way.
1385
1386If this call isn't available because your OS lacks it or it couldn't be
1387detected, it will be emulated by calling C<fsync> instead.
1388
1389=item IO::AIO::CWD
1390
1391This is a compiletime constant (object) that represents the process
1392current working directory.
1393
1394Specifying this object as working directory object for a pathname is as
1395if the pathname would be specified directly, without a directory object,
1396e.g., these calls are functionally identical:
1397
1398 aio_stat "somefile", sub { ... };
1399 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1400
1401=back
1402
1037 1403
1038=head2 IO::AIO::REQ CLASS 1404=head2 IO::AIO::REQ CLASS
1039 1405
1040All non-aggregate C<aio_*> functions return an object of this class when 1406All non-aggregate C<aio_*> functions return an object of this class when
1041called in non-void context. 1407called in non-void context.
… …
1131=item $grp->cancel_subs 1497=item $grp->cancel_subs
1132 1498
1133Cancel all subrequests and clears any feeder, but not the group request 1499Cancel all subrequests and clears any feeder, but not the group request
1134itself. Useful when you queued a lot of events but got a result early. 1500itself. Useful when you queued a lot of events but got a result early.
1135 1501
1502The group request will finish normally (you cannot add requests to the
1503group).
1504
1136=item $grp->result (...) 1505=item $grp->result (...)
1137 1506
1138Set the result value(s) that will be passed to the group callback when all 1507Set the result value(s) that will be passed to the group callback when all
1139subrequests have finished and set the groups errno to the current value 1508subrequests have finished and set the groups errno to the current value
1140of errno (just like calling C<errno> without an error number). By default, 1509of errno (just like calling C<errno> without an error number). By default,
… …
1156 1525
1157Sets a feeder/generator on this group: every group can have an attached 1526Sets a feeder/generator on this group: every group can have an attached
1158generator that generates requests if idle. The idea behind this is that, 1527generator that generates requests if idle. The idea behind this is that,
1159although you could just queue as many requests as you want in a group, 1528although you could just queue as many requests as you want in a group,
1160this might starve other requests for a potentially long time. For example, 1529this might starve other requests for a potentially long time. For example,
1161C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, 1530C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1162delaying any later requests for a long time. 1531requests, delaying any later requests for a long time.
1163 1532
1164To avoid this, and allow incremental generation of requests, you can 1533To avoid this, and allow incremental generation of requests, you can
1165instead a group and set a feeder on it that generates those requests. The 1534instead a group and set a feeder on it that generates those requests. The
1166feed callback will be called whenever there are few enough (see C<limit>, 1535feed callback will be called whenever there are few enough (see C<limit>,
1167below) requests active in the group itself and is expected to queue more 1536below) requests active in the group itself and is expected to queue more
… …
1208=over 4 1577=over 4
1209 1578
1210=item $fileno = IO::AIO::poll_fileno 1579=item $fileno = IO::AIO::poll_fileno
1211 1580
1212Return the I<request result pipe file descriptor>. This filehandle must be 1581Return the I<request result pipe file descriptor>. This filehandle must be
1213polled for reading by some mechanism outside this module (e.g. Event or 1582polled for reading by some mechanism outside this module (e.g. EV, Glib,
1214select, see below or the SYNOPSIS). If the pipe becomes readable you have 1583select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1215to call C<poll_cb> to check the results. 1584you have to call C<poll_cb> to check the results.
1216 1585
1217See C<poll_cb> for an example. 1586See C<poll_cb> for an example.
1218 1587
1219=item IO::AIO::poll_cb 1588=item IO::AIO::poll_cb
1220 1589
1221Process some outstanding events on the result pipe. You have to call this 1590Process some outstanding events on the result pipe. You have to call
1222regularly. Returns C<0> if all events could be processed, or C<-1> if it 1591this regularly. Returns C<0> if all events could be processed (or there
1223returned earlier for whatever reason. Returns immediately when no events 1592were no events to process), or C<-1> if it returned earlier for whatever
1224are outstanding. The amount of events processed depends on the settings of 1593reason. Returns immediately when no events are outstanding. The amount of
1225C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1594events processed depends on the settings of C<IO::AIO::max_poll_req> and
1595C<IO::AIO::max_poll_time>.
1226 1596
1227If not all requests were processed for whatever reason, the filehandle 1597If not all requests were processed for whatever reason, the filehandle
1228will still be ready when C<poll_cb> returns, so normally you don't have to 1598will still be ready when C<poll_cb> returns, so normally you don't have to
1229do anything special to have it called later. 1599do anything special to have it called later.
1230 1600
1601Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1602ready, it can be beneficial to call this function from loops which submit
1603a lot of requests, to make sure the results get processed when they become
1604available and not just when the loop is finished and the event loop takes
1605over again. This function returns very fast when there are no outstanding
1606requests.
1607
1231Example: Install an Event watcher that automatically calls 1608Example: Install an Event watcher that automatically calls
1232IO::AIO::poll_cb with high priority: 1609IO::AIO::poll_cb with high priority (more examples can be found in the
1610SYNOPSIS section, at the top of this document):
1233 1611
1234 Event->io (fd => IO::AIO::poll_fileno, 1612 Event->io (fd => IO::AIO::poll_fileno,
1235 poll => 'r', async => 1, 1613 poll => 'r', async => 1,
1236 cb => \&IO::AIO::poll_cb); 1614 cb => \&IO::AIO::poll_cb);
1615
1616=item IO::AIO::poll_wait
1617
1618If there are any outstanding requests and none of them in the result
1619phase, wait till the result filehandle becomes ready for reading (simply
1620does a C<select> on the filehandle. This is useful if you want to
1621synchronously wait for some requests to finish).
1622
1623See C<nreqs> for an example.
1624
1625=item IO::AIO::poll
1626
1627Waits until some requests have been handled.
1628
1629Returns the number of requests processed, but is otherwise strictly
1630equivalent to:
1631
1632 IO::AIO::poll_wait, IO::AIO::poll_cb
1633
1634=item IO::AIO::flush
1635
1636Wait till all outstanding AIO requests have been handled.
1637
1638Strictly equivalent to:
1639
1640 IO::AIO::poll_wait, IO::AIO::poll_cb
1641 while IO::AIO::nreqs;
1237 1642
1238=item IO::AIO::max_poll_reqs $nreqs 1643=item IO::AIO::max_poll_reqs $nreqs
1239 1644
1240=item IO::AIO::max_poll_time $seconds 1645=item IO::AIO::max_poll_time $seconds
1241 1646
… …
1266 # use a low priority so other tasks have priority 1671 # use a low priority so other tasks have priority
1267 Event->io (fd => IO::AIO::poll_fileno, 1672 Event->io (fd => IO::AIO::poll_fileno,
1268 poll => 'r', nice => 1, 1673 poll => 'r', nice => 1,
1269 cb => &IO::AIO::poll_cb); 1674 cb => &IO::AIO::poll_cb);
1270 1675
1271=item IO::AIO::poll_wait
1272
1273If there are any outstanding requests and none of them in the result
1274phase, wait till the result filehandle becomes ready for reading (simply
1275does a C<select> on the filehandle. This is useful if you want to
1276synchronously wait for some requests to finish).
1277
1278See C<nreqs> for an example.
1279
1280=item IO::AIO::poll
1281
1282Waits until some requests have been handled.
1283
1284Returns the number of requests processed, but is otherwise strictly
1285equivalent to:
1286
1287 IO::AIO::poll_wait, IO::AIO::poll_cb
1288
1289=item IO::AIO::flush
1290
1291Wait till all outstanding AIO requests have been handled.
1292
1293Strictly equivalent to:
1294
1295 IO::AIO::poll_wait, IO::AIO::poll_cb
1296 while IO::AIO::nreqs;
1297
1298=back 1676=back
1299 1677
1300=head3 CONTROLLING THE NUMBER OF THREADS 1678=head3 CONTROLLING THE NUMBER OF THREADS
1301 1679
1302=over 1680=over
… …
1335 1713
1336Under normal circumstances you don't need to call this function. 1714Under normal circumstances you don't need to call this function.
1337 1715
1338=item IO::AIO::max_idle $nthreads 1716=item IO::AIO::max_idle $nthreads
1339 1717
1340Limit the number of threads (default: 4) that are allowed to idle (i.e., 1718Limit the number of threads (default: 4) that are allowed to idle
1341threads that did not get a request to process within 10 seconds). That 1719(i.e., threads that did not get a request to process within the idle
1342means if a thread becomes idle while C<$nthreads> other threads are also 1720timeout (default: 10 seconds). That means if a thread becomes idle while
1343idle, it will free its resources and exit. 1721C<$nthreads> other threads are also idle, it will free its resources and
1722exit.
1344 1723
1345This is useful when you allow a large number of threads (e.g. 100 or 1000) 1724This is useful when you allow a large number of threads (e.g. 100 or 1000)
1346to allow for extremely high load situations, but want to free resources 1725to allow for extremely high load situations, but want to free resources
1347under normal circumstances (1000 threads can easily consume 30MB of RAM). 1726under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348 1727
1349The default is probably ok in most situations, especially if thread 1728The default is probably ok in most situations, especially if thread
1350creation is fast. If thread creation is very slow on your system you might 1729creation is fast. If thread creation is very slow on your system you might
1351want to use larger values. 1730want to use larger values.
1352 1731
1732=item IO::AIO::idle_timeout $seconds
1733
1734Sets the minimum idle timeout (default 10) after which worker threads are
1735allowed to exit. SEe C<IO::AIO::max_idle>.
1736
1353=item IO::AIO::max_outstanding $maxreqs 1737=item IO::AIO::max_outstanding $maxreqs
1738
1739Sets the maximum number of outstanding requests to C<$nreqs>. If
1740you do queue up more than this number of requests, the next call to
1741C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1742C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1743longer exceeded.
1744
1745In other words, this setting does not enforce a queue limit, but can be
1746used to make poll functions block if the limit is exceeded.
1354 1747
1355This is a very bad function to use in interactive programs because it 1748This is a very bad function to use in interactive programs because it
1356blocks, and a bad way to reduce concurrency because it is inexact: Better 1749blocks, and a bad way to reduce concurrency because it is inexact: Better
1357use an C<aio_group> together with a feed callback. 1750use an C<aio_group> together with a feed callback.
1358 1751
1359Sets the maximum number of outstanding requests to C<$nreqs>. If you 1752It's main use is in scripts without an event loop - when you want to stat
1360do queue up more than this number of requests, the next call to the 1753a lot of files, you can write somehting like this:
1361C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1362function will block until the limit is no longer exceeded.
1363 1754
1364The default value is very large, so there is no practical limit on the 1755 IO::AIO::max_outstanding 32;
1365number of outstanding requests.
1366 1756
1367You can still queue as many requests as you want. Therefore, 1757 for my $path (...) {
1368C<max_outstanding> is mainly useful in simple scripts (with low values) or 1758 aio_stat $path , ...;
1369as a stop gap to shield against fatal memory overflow (with large values). 1759 IO::AIO::poll_cb;
1760 }
1761
1762 IO::AIO::flush;
1763
1764The call to C<poll_cb> inside the loop will normally return instantly, but
1765as soon as more thna C<32> reqeusts are in-flight, it will block until
1766some requests have been handled. This keeps the loop from pushing a large
1767number of C<aio_stat> requests onto the queue.
1768
1769The default value for C<max_outstanding> is very large, so there is no
1770practical limit on the number of outstanding requests.
1370 1771
1371=back 1772=back
1372 1773
1373=head3 STATISTICAL INFORMATION 1774=head3 STATISTICAL INFORMATION
1374 1775
… …
1394Returns the number of requests currently in the pending state (executed, 1795Returns the number of requests currently in the pending state (executed,
1395but not yet processed by poll_cb). 1796but not yet processed by poll_cb).
1396 1797
1397=back 1798=back
1398 1799
1800=head3 MISCELLANEOUS FUNCTIONS
1801
1802IO::AIO implements some functions that might be useful, but are not
1803asynchronous.
1804
1805=over 4
1806
1807=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1808
1809Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1810but is blocking (this makes most sense if you know the input data is
1811likely cached already and the output filehandle is set to non-blocking
1812operations).
1813
1814Returns the number of bytes copied, or C<-1> on error.
1815
1816=item IO::AIO::fadvise $fh, $offset, $len, $advice
1817
1818Simply calls the C<posix_fadvise> function (see its
1819manpage for details). The following advice constants are
1820available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1821C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1822C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1823
1824On systems that do not implement C<posix_fadvise>, this function returns
1825ENOSYS, otherwise the return value of C<posix_fadvise>.
1826
1827=item IO::AIO::madvise $scalar, $offset, $len, $advice
1828
1829Simply calls the C<posix_madvise> function (see its
1830manpage for details). The following advice constants are
1831available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1832C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1833
1834On systems that do not implement C<posix_madvise>, this function returns
1835ENOSYS, otherwise the return value of C<posix_madvise>.
1836
1837=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1838
1839Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1840$scalar (see its manpage for details). The following protect
1841constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1842C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1843
1844On systems that do not implement C<mprotect>, this function returns
1845ENOSYS, otherwise the return value of C<mprotect>.
1846
1847=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1848
1849Memory-maps a file (or anonymous memory range) and attaches it to the
1850given C<$scalar>, which will act like a string scalar.
1851
1852The only operations allowed on the scalar are C<substr>/C<vec> that don't
1853change the string length, and most read-only operations such as copying it
1854or searching it with regexes and so on.
1855
1856Anything else is unsafe and will, at best, result in memory leaks.
1857
1858The memory map associated with the C<$scalar> is automatically removed
1859when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
1860C<IO::AIO::munmap> functions are called.
1861
1862This calls the C<mmap>(2) function internally. See your system's manual
1863page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1864
1865The C<$length> must be larger than zero and smaller than the actual
1866filesize.
1867
1868C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1869C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1870
1871C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
1872C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
1873not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
1874(which is set to C<MAP_ANON> if your system only provides this
1875constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
1876C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1877C<IO::AIO::MAP_NONBLOCK>
1878
1879If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1880
1881C<$offset> is the offset from the start of the file - it generally must be
1882a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1883
1884Example:
1885
1886 use Digest::MD5;
1887 use IO::AIO;
1888
1889 open my $fh, "<verybigfile"
1890 or die "$!";
1891
1892 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1893 or die "verybigfile: $!";
1894
1895 my $fast_md5 = md5 $data;
1896
1897=item IO::AIO::munmap $scalar
1898
1899Removes a previous mmap and undefines the C<$scalar>.
1900
1901=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1902
1903Calls the C<munlock> function, undoing the effects of a previous
1904C<aio_mlock> call (see its description for details).
1905
1906=item IO::AIO::munlockall
1907
1908Calls the C<munlockall> function.
1909
1910On systems that do not implement C<munlockall>, this function returns
1911ENOSYS, otherwise the return value of C<munlockall>.
1912
1913=back
1914
1399=cut 1915=cut
1400 1916
1401min_parallel 8; 1917min_parallel 8;
1402 1918
1403END { flush } 1919END { flush }
1404 1920
14051; 19211;
1406 1922
1923=head1 EVENT LOOP INTEGRATION
1924
1925It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
1926automatically into many event loops:
1927
1928 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1929 use AnyEvent::AIO;
1930
1931You can also integrate IO::AIO manually into many event loops, here are
1932some examples of how to do this:
1933
1934 # EV integration
1935 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1936
1937 # Event integration
1938 Event->io (fd => IO::AIO::poll_fileno,
1939 poll => 'r',
1940 cb => \&IO::AIO::poll_cb);
1941
1942 # Glib/Gtk2 integration
1943 add_watch Glib::IO IO::AIO::poll_fileno,
1944 in => sub { IO::AIO::poll_cb; 1 };
1945
1946 # Tk integration
1947 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1948 readable => \&IO::AIO::poll_cb);
1949
1950 # Danga::Socket integration
1951 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1952 \&IO::AIO::poll_cb);
1953
1407=head2 FORK BEHAVIOUR 1954=head2 FORK BEHAVIOUR
1408 1955
1409This module should do "the right thing" when the process using it forks: 1956Usage of pthreads in a program changes the semantics of fork
1957considerably. Specifically, only async-safe functions can be called after
1958fork. Perl doesn't know about this, so in general, you cannot call fork
1959with defined behaviour in perl if pthreads are involved. IO::AIO uses
1960pthreads, so this applies, but many other extensions and (for inexplicable
1961reasons) perl itself often is linked against pthreads, so this limitation
1962applies to quite a lot of perls.
1410 1963
1411Before the fork, IO::AIO enters a quiescent state where no requests 1964This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1412can be added in other threads and no results will be processed. After 1965only works in the process that loaded it. Forking is fully supported, but
1413the fork the parent simply leaves the quiescent state and continues 1966using IO::AIO in the child is not.
1414request/result processing, while the child frees the request/result queue
1415(so that the requests started before the fork will only be handled in the
1416parent). Threads will be started on demand until the limit set in the
1417parent process has been reached again.
1418 1967
1419In short: the parent will, after a short pause, continue as if fork had 1968You might get around by not I<using> IO::AIO before (or after)
1420not been called, while the child will act as if IO::AIO has not been used 1969forking. You could also try to call the L<IO::AIO::reinit> function in the
1421yet. 1970child:
1971
1972=over 4
1973
1974=item IO::AIO::reinit
1975
1976Abandons all current requests and I/O threads and simply reinitialises all
1977data structures. This is not an operation supported by any standards, but
1978happens to work on GNU/Linux and some newer BSD systems.
1979
1980The only reasonable use for this function is to call it after forking, if
1981C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
1982the process will result in undefined behaviour. Calling it at any time
1983will also result in any undefined (by POSIX) behaviour.
1984
1985=back
1422 1986
1423=head2 MEMORY USAGE 1987=head2 MEMORY USAGE
1424 1988
1425Per-request usage: 1989Per-request usage:
1426 1990

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