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Revision 1.172 by root, Thu Jan 7 18:08:21 2010 UTC vs.
Revision 1.220 by root, Sun Apr 1 17:46:02 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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25 my $req = aio_unlink "/tmp/file", sub { }; 25 my $req = aio_unlink "/tmp/file", sub { };
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
31 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32 use AnyEvent::AIO;
33
34 # EV integration
35 my $aio_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 30
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. It is implemented as an interface to C<libeio> 34operating system supports. It is implemented as an interface to C<libeio>
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99 76
100 # register the IO::AIO callback with EV 77 # register the IO::AIO callback with EV
101 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
102 79
103 # queue the request to open /etc/passwd 80 # queue the request to open /etc/passwd
104 aio_open "/etc/passwd", O_RDONLY, 0, sub { 81 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
105 my $fh = shift 82 my $fh = shift
106 or die "error while opening: $!"; 83 or die "error while opening: $!";
107 84
108 # stat'ing filehandles is generally non-blocking 85 # stat'ing filehandles is generally non-blocking
109 my $size = -s $fh; 86 my $size = -s $fh;
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191use common::sense; 168use common::sense;
192 169
193use base 'Exporter'; 170use base 'Exporter';
194 171
195BEGIN { 172BEGIN {
196 our $VERSION = '3.4'; 173 our $VERSION = '4.13';
197 174
198 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 175 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
199 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
200 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync 177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
201 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
202 aio_rename aio_link aio_move aio_copy aio_group 180 aio_rename aio_link aio_move aio_copy aio_group
203 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
204 aio_chmod aio_utime aio_truncate 182 aio_chmod aio_utime aio_truncate
205 aio_msync aio_mtouch aio_statvfs); 183 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs
185 aio_wd);
206 186
207 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
208 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
209 min_parallel max_parallel max_idle 189 min_parallel max_parallel max_idle idle_timeout
210 nreqs nready npending nthreads 190 nreqs nready npending nthreads
211 max_poll_time max_poll_reqs 191 max_poll_time max_poll_reqs
212 sendfile fadvise); 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_seek $fh,$offset,$whence, $callback->($offs)
215 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
217 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
218 aio_readahead $fh,$offset,$length, $callback->($retval)
219 aio_stat $fh_or_path, $callback->($status)
220 aio_lstat $fh, $callback->($status)
221 aio_statvfs $fh_or_path, $callback->($statvfs)
222 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
223 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status)
225 aio_truncate $fh_or_path, $offset, $callback->($status)
226 aio_unlink $pathname, $callback->($status)
227 aio_mknod $pathname, $mode, $dev, $callback->($status)
228 aio_link $srcpath, $dstpath, $callback->($status)
229 aio_symlink $srcpath, $dstpath, $callback->($status)
230 aio_readlink $pathname, $callback->($link)
231 aio_realpath $pathname, $callback->($link)
232 aio_rename $srcpath, $dstpath, $callback->($status)
233 aio_mkdir $pathname, $mode, $callback->($status)
234 aio_rmdir $pathname, $callback->($status)
235 aio_readdir $pathname, $callback->($entries)
236 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
237 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
238 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
239 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
240 aio_load $pathname, $data, $callback->($status)
241 aio_copy $srcpath, $dstpath, $callback->($status)
242 aio_move $srcpath, $dstpath, $callback->($status)
243 aio_rmtree $pathname, $callback->($status)
244 aio_sync $callback->($status)
245 aio_syncfs $fh, $callback->($status)
246 aio_fsync $fh, $callback->($status)
247 aio_fdatasync $fh, $callback->($status)
248 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
249 aio_pathsync $pathname, $callback->($status)
250 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
252 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
253 aio_mlockall $flags, $callback->($status)
254 aio_group $callback->(...)
255 aio_nop $callback->()
256
257 $prev_pri = aioreq_pri [$pri]
258 aioreq_nice $pri_adjust
259
260 IO::AIO::poll_wait
261 IO::AIO::poll_cb
262 IO::AIO::poll
263 IO::AIO::flush
264 IO::AIO::max_poll_reqs $nreqs
265 IO::AIO::max_poll_time $seconds
266 IO::AIO::min_parallel $nthreads
267 IO::AIO::max_parallel $nthreads
268 IO::AIO::max_idle $nthreads
269 IO::AIO::idle_timeout $seconds
270 IO::AIO::max_outstanding $maxreqs
271 IO::AIO::nreqs
272 IO::AIO::nready
273 IO::AIO::npending
274
275 IO::AIO::sendfile $ofh, $ifh, $offset, $count
276 IO::AIO::fadvise $fh, $offset, $len, $advice
277 IO::AIO::madvise $scalar, $offset, $length, $advice
278 IO::AIO::mprotect $scalar, $offset, $length, $protect
279 IO::AIO::munlock $scalar, $offset = 0, $length = undef
280 IO::AIO::munlockall
281
282=head2 API NOTES
225 283
226All the C<aio_*> calls are more or less thin wrappers around the syscall 284All the C<aio_*> calls are more or less thin wrappers around the syscall
227with the same name (sans C<aio_>). The arguments are similar or identical, 285with the same name (sans C<aio_>). The arguments are similar or identical,
228and they all accept an additional (and optional) C<$callback> argument 286and they all accept an additional (and optional) C<$callback> argument
229which must be a code reference. This code reference will get called with 287which must be a code reference. This code reference will be called after
230the syscall return code (e.g. most syscalls return C<-1> on error, unlike 288the syscall has been executed in an asynchronous fashion. The results
231perl, which usually delivers "false") as its sole argument after the given 289of the request will be passed as arguments to the callback (and, if an
232syscall has been executed asynchronously. 290error occured, in C<$!>) - for most requests the syscall return code (e.g.
291most syscalls return C<-1> on error, unlike perl, which usually delivers
292"false").
293
294Some requests (such as C<aio_readdir>) pass the actual results and
295communicate failures by passing C<undef>.
233 296
234All functions expecting a filehandle keep a copy of the filehandle 297All functions expecting a filehandle keep a copy of the filehandle
235internally until the request has finished. 298internally until the request has finished.
236 299
237All functions return request objects of type L<IO::AIO::REQ> that allow 300All functions return request objects of type L<IO::AIO::REQ> that allow
238further manipulation of those requests while they are in-flight. 301further manipulation of those requests while they are in-flight.
239 302
240The pathnames you pass to these routines I<must> be absolute and 303The 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 304reason for this is that at the time the request is being executed, the
242request is being executed, the current working directory could have 305current working directory could have changed. Alternatively, you can
243changed. Alternatively, you can make sure that you never change the 306make sure that you never change the current working directory anywhere
244current working directory anywhere in the program and then use relative 307in the program and then use relative paths. You can also take advantage
245paths. 308of IO::AIOs working directory abstraction, that lets you specify paths
309relative to some previously-opened "working directory object" - see the
310description of the C<IO::AIO::WD> class later in this document.
246 311
247To encode pathnames as octets, either make sure you either: a) always pass 312To encode pathnames as octets, either make sure you either: a) always pass
248in filenames you got from outside (command line, readdir etc.) without 313in 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 314tinkering, b) are in your native filesystem encoding, c) use the Encode
250your pathnames to the locale (or other) encoding in effect in the user 315module and encode your pathnames to the locale (or other) encoding in
251environment, d) use Glib::filename_from_unicode on unicode filenames or e) 316effect in the user environment, d) use Glib::filename_from_unicode on
252use something else to ensure your scalar has the correct contents. 317unicode filenames or e) use something else to ensure your scalar has the
318correct contents.
253 319
254This works, btw. independent of the internal UTF-8 bit, which IO::AIO 320This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255handles correctly whether it is set or not. 321handles correctly whether it is set or not.
322
323=head2 AIO REQUEST FUNCTIONS
256 324
257=over 4 325=over 4
258 326
259=item $prev_pri = aioreq_pri [$pri] 327=item $prev_pri = aioreq_pri [$pri]
260 328
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307by the umask in effect then the request is being executed, so better never 375by the umask in effect then the request is being executed, so better never
308change the umask. 376change the umask.
309 377
310Example: 378Example:
311 379
312 aio_open "/etc/passwd", O_RDONLY, 0, sub { 380 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313 if ($_[0]) { 381 if ($_[0]) {
314 print "open successful, fh is $_[0]\n"; 382 print "open successful, fh is $_[0]\n";
315 ... 383 ...
316 } else { 384 } else {
317 die "open failed: $!\n"; 385 die "open failed: $!\n";
318 } 386 }
319 }; 387 };
320 388
389In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
390C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
391following POSIX and non-POSIX constants are available (missing ones on
392your system are, as usual, C<0>):
393
394C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
395C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
396C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
397
321 398
322=item aio_close $fh, $callback->($status) 399=item aio_close $fh, $callback->($status)
323 400
324Asynchronously close a file and call the callback with the result 401Asynchronously close a file and call the callback with the result
325code. 402code.
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333 410
334Or in other words: the file descriptor will be closed, but it will not be 411Or in other words: the file descriptor will be closed, but it will not be
335free for reuse until the perl filehandle is closed. 412free for reuse until the perl filehandle is closed.
336 413
337=cut 414=cut
415
416=item aio_seek $fh, $offset, $whence, $callback->($offs)
417
418Seeks the filehandle to the new C<$offset>, similarly to perl'S
419C<sysseek>. The C<$whence> can use the traditional values (C<0> for
420C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
421C<IO::AIO::SEEK_END>).
422
423The resulting absolute offset will be passed to the callback, or C<-1> in
424case of an error.
425
426In theory, the C<$whence> constants could be different than the
427corresponding values from L<Fcntl>, but perl guarantees they are the same,
428so don't panic.
338 429
339=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 430=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340 431
341=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 432=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342 433
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375 466
376Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 467Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377reading at byte offset C<$in_offset>, and starts writing at the current 468reading at byte offset C<$in_offset>, and starts writing at the current
378file offset of C<$out_fh>. Because of that, it is not safe to issue more 469file offset of C<$out_fh>. Because of that, it is not safe to issue more
379than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 470than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380other. 471other. The same C<$in_fh> works fine though, as this function does not
472move or use the file offset of C<$in_fh>.
381 473
474Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
475are written, and there is no way to find out how many more bytes have been
476read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
477number of bytes written to C<$out_fh>. Only if the result value equals
478C<$length> one can assume that C<$length> bytes have been read.
479
480Unlike with other C<aio_> functions, it makes a lot of sense to use
481C<aio_sendfile> on non-blocking sockets, as long as one end (typically
482the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
483the socket I/O will be non-blocking. Note, however, that you can run
484into a trap where C<aio_sendfile> reads some data with readahead, then
485fails to write all data, and when the socket is ready the next time, the
486data in the cache is already lost, forcing C<aio_sendfile> to again hit
487the disk. Explicit C<aio_read> + C<aio_write> let's you better control
488resource usage.
489
382This call tries to make use of a native C<sendfile> syscall to provide 490This call tries to make use of a native C<sendfile>-like syscall to
383zero-copy operation. For this to work, C<$out_fh> should refer to a 491provide zero-copy operation. For this to work, C<$out_fh> should refer to
384socket, and C<$in_fh> should refer to mmap'able file. 492a socket, and C<$in_fh> should refer to an mmap'able file.
385 493
386If a native sendfile cannot be found or it fails with C<ENOSYS>, 494If a native sendfile cannot be found or it fails with C<ENOSYS>,
387C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>, 495C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
388it will be emulated, so you can call C<aio_sendfile> on any type of 496C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
389filehandle regardless of the limitations of the operating system. 497type of filehandle regardless of the limitations of the operating system.
390 498
391Please note, however, that C<aio_sendfile> can read more bytes from 499As native sendfile syscalls (as practically any non-POSIX interface hacked
392C<$in_fh> than are written, and there is no way to find out how many 500together in a hurry to improve benchmark numbers) tend to be rather buggy
393bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 501on many systems, this implementation tries to work around some known bugs
394provides the number of bytes written to C<$out_fh>. Only if the result 502in Linux and FreeBSD kernels (probably others, too), but that might fail,
395value equals C<$length> one can assume that C<$length> bytes have been 503so you really really should check the return value of C<aio_sendfile> -
396read. 504fewre bytes than expected might have been transferred.
397 505
398 506
399=item aio_readahead $fh,$offset,$length, $callback->($retval) 507=item aio_readahead $fh,$offset,$length, $callback->($retval)
400 508
401C<aio_readahead> populates the page cache with data from a file so that 509C<aio_readahead> populates the page cache with data from a file so that
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424 532
425Currently, the stats are always 64-bit-stats, i.e. instead of returning an 533Currently, the stats are always 64-bit-stats, i.e. instead of returning an
426error when stat'ing a large file, the results will be silently truncated 534error when stat'ing a large file, the results will be silently truncated
427unless perl itself is compiled with large file support. 535unless perl itself is compiled with large file support.
428 536
537To help interpret the mode and dev/rdev stat values, IO::AIO offers the
538following constants and functions (if not implemented, the constants will
539be C<0> and the functions will either C<croak> or fall back on traditional
540behaviour).
541
542C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
543C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
544C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
545
429Example: Print the length of F</etc/passwd>: 546Example: Print the length of F</etc/passwd>:
430 547
431 aio_stat "/etc/passwd", sub { 548 aio_stat "/etc/passwd", sub {
432 $_[0] and die "stat failed: $!"; 549 $_[0] and die "stat failed: $!";
433 print "size is ", -s _, "\n"; 550 print "size is ", -s _, "\n";
434 }; 551 };
435 552
436 553
437=item aio_statvfs $fh_or_path, $callback->($statvfs) 554=item aio_statvfs $fh_or_path, $callback->($statvfs)
438 555
439Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on 556Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
440whether a file handle or path was passed. 557whether a file handle or path was passed.
441 558
442On success, the callback is passed a hash reference with the following 559On success, the callback is passed a hash reference with the following
… …
524 641
525Asynchronously unlink (delete) a file and call the callback with the 642Asynchronously unlink (delete) a file and call the callback with the
526result code. 643result code.
527 644
528 645
529=item aio_mknod $path, $mode, $dev, $callback->($status) 646=item aio_mknod $pathname, $mode, $dev, $callback->($status)
530 647
531[EXPERIMENTAL] 648[EXPERIMENTAL]
532 649
533Asynchronously create a device node (or fifo). See mknod(2). 650Asynchronously create a device node (or fifo). See mknod(2).
534 651
535The only (POSIX-) portable way of calling this function is: 652The only (POSIX-) portable way of calling this function is:
536 653
537 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 654 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
538 655
656See C<aio_stat> for info about some potentially helpful extra constants
657and functions.
539 658
540=item aio_link $srcpath, $dstpath, $callback->($status) 659=item aio_link $srcpath, $dstpath, $callback->($status)
541 660
542Asynchronously create a new link to the existing object at C<$srcpath> at 661Asynchronously create a new link to the existing object at C<$srcpath> at
543the path C<$dstpath> and call the callback with the result code. 662the path C<$dstpath> and call the callback with the result code.
… …
547 666
548Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 667Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
549the path C<$dstpath> and call the callback with the result code. 668the path C<$dstpath> and call the callback with the result code.
550 669
551 670
552=item aio_readlink $path, $callback->($link) 671=item aio_readlink $pathname, $callback->($link)
553 672
554Asynchronously read the symlink specified by C<$path> and pass it to 673Asynchronously read the symlink specified by C<$path> and pass it to
555the callback. If an error occurs, nothing or undef gets passed to the 674the callback. If an error occurs, nothing or undef gets passed to the
556callback. 675callback.
557 676
558 677
678=item aio_realpath $pathname, $callback->($path)
679
680Asynchronously make the path absolute and resolve any symlinks in
681C<$path>. The resulting path only consists of directories (Same as
682L<Cwd::realpath>).
683
684This request can be used to get the absolute path of the current working
685directory by passing it a path of F<.> (a single dot).
686
687
559=item aio_rename $srcpath, $dstpath, $callback->($status) 688=item aio_rename $srcpath, $dstpath, $callback->($status)
560 689
561Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 690Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
562rename(2) and call the callback with the result code. 691rename(2) and call the callback with the result code.
563 692
… …
585array-ref with the filenames. 714array-ref with the filenames.
586 715
587 716
588=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) 717=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
589 718
590Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune 719Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
591behaviour and output format. In case of an error, C<$entries> will be 720tune behaviour and output format. In case of an error, C<$entries> will be
592C<undef>. 721C<undef>.
593 722
594The flags are a combination of the following constants, ORed together (the 723The flags are a combination of the following constants, ORed together (the
595flags will also be passed to the callback, possibly modified): 724flags will also be passed to the callback, possibly modified):
596 725
597=over 4 726=over 4
598 727
599=item IO::AIO::READDIR_DENTS 728=item IO::AIO::READDIR_DENTS
600 729
601When this flag is off, then the callback gets an arrayref with of names 730When this flag is off, then the callback gets an arrayref consisting of
602only (as with C<aio_readdir>), otherwise it gets an arrayref with 731names only (as with C<aio_readdir>), otherwise it gets an arrayref with
603C<[$name, $type, $inode]> arrayrefs, each describing a single directory 732C<[$name, $type, $inode]> arrayrefs, each describing a single directory
604entry in more detail. 733entry in more detail.
605 734
606C<$name> is the name of the entry. 735C<$name> is the name of the entry.
607 736
… …
620systems that do not deliver the inode information. 749systems that do not deliver the inode information.
621 750
622=item IO::AIO::READDIR_DIRS_FIRST 751=item IO::AIO::READDIR_DIRS_FIRST
623 752
624When this flag is set, then the names will be returned in an order where 753When this flag is set, then the names will be returned in an order where
625likely directories come first. This is useful when you need to quickly 754likely directories come first, in optimal stat order. This is useful when
626find directories, or you want to find all directories while avoiding to 755you need to quickly find directories, or you want to find all directories
627stat() each entry. 756while avoiding to stat() each entry.
628 757
629If the system returns type information in readdir, then this is used 758If the system returns type information in readdir, then this is used
630to find directories directly. Otherwise, likely directories are files 759to find directories directly. Otherwise, likely directories are names
631beginning with ".", or otherwise files with no dots, of which files with 760beginning with ".", or otherwise names with no dots, of which names with
632short names are tried first. 761short names are tried first.
633 762
634=item IO::AIO::READDIR_STAT_ORDER 763=item IO::AIO::READDIR_STAT_ORDER
635 764
636When this flag is set, then the names will be returned in an order 765When this flag is set, then the names will be returned in an order
… …
643 772
644=item IO::AIO::READDIR_FOUND_UNKNOWN 773=item IO::AIO::READDIR_FOUND_UNKNOWN
645 774
646This flag should not be set when calling C<aio_readdirx>. Instead, it 775This flag should not be set when calling C<aio_readdirx>. Instead, it
647is being set by C<aio_readdirx>, when any of the C<$type>'s found were 776is being set by C<aio_readdirx>, when any of the C<$type>'s found were
648C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all 777C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
649C<$type>'s are known, which can be used to speed up some algorithms. 778C<$type>'s are known, which can be used to speed up some algorithms.
650 779
651=back 780=back
652 781
653 782
654=item aio_load $path, $data, $callback->($status) 783=item aio_load $pathname, $data, $callback->($status)
655 784
656This is a composite request that tries to fully load the given file into 785This is a composite request that tries to fully load the given file into
657memory. Status is the same as with aio_read. 786memory. Status is the same as with aio_read.
658 787
659=cut 788=cut
… …
781 if ($_[0] && $! == EXDEV) { 910 if ($_[0] && $! == EXDEV) {
782 aioreq_pri $pri; 911 aioreq_pri $pri;
783 add $grp aio_copy $src, $dst, sub { 912 add $grp aio_copy $src, $dst, sub {
784 $grp->result ($_[0]); 913 $grp->result ($_[0]);
785 914
786 if (!$_[0]) { 915 unless ($_[0]) {
787 aioreq_pri $pri; 916 aioreq_pri $pri;
788 add $grp aio_unlink $src; 917 add $grp aio_unlink $src;
789 } 918 }
790 }; 919 };
791 } else { 920 } else {
… …
794 }; 923 };
795 924
796 $grp 925 $grp
797} 926}
798 927
799=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 928=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
800 929
801Scans a directory (similar to C<aio_readdir>) but additionally tries to 930Scans a directory (similar to C<aio_readdir>) but additionally tries to
802efficiently separate the entries of directory C<$path> into two sets of 931efficiently separate the entries of directory C<$path> into two sets of
803names, directories you can recurse into (directories), and ones you cannot 932names, directories you can recurse into (directories), and ones you cannot
804recurse into (everything else, including symlinks to directories). 933recurse into (everything else, including symlinks to directories).
… …
835Then entries will be sorted into likely directories a non-initial dot 964Then entries will be sorted into likely directories a non-initial dot
836currently) and likely non-directories (see C<aio_readdirx>). Then every 965currently) and likely non-directories (see C<aio_readdirx>). Then every
837entry plus an appended C</.> will be C<stat>'ed, likely directories first, 966entry plus an appended C</.> will be C<stat>'ed, likely directories first,
838in order of their inode numbers. If that succeeds, it assumes that the 967in order of their inode numbers. If that succeeds, it assumes that the
839entry is a directory or a symlink to directory (which will be checked 968entry is a directory or a symlink to directory (which will be checked
840seperately). This is often faster than stat'ing the entry itself because 969separately). This is often faster than stat'ing the entry itself because
841filesystems might detect the type of the entry without reading the inode 970filesystems might detect the type of the entry without reading the inode
842data (e.g. ext2fs filetype feature), even on systems that cannot return 971data (e.g. ext2fs filetype feature), even on systems that cannot return
843the filetype information on readdir. 972the filetype information on readdir.
844 973
845If the known number of directories (link count - 2) has been reached, the 974If the known number of directories (link count - 2) has been reached, the
… …
861 990
862 my $grp = aio_group $cb; 991 my $grp = aio_group $cb;
863 992
864 $maxreq = 4 if $maxreq <= 0; 993 $maxreq = 4 if $maxreq <= 0;
865 994
866 # stat once 995 # get a wd object
867 aioreq_pri $pri; 996 aioreq_pri $pri;
868 add $grp aio_stat $path, sub { 997 add $grp aio_wd $path, sub {
998 $_[0]
869 return $grp->result () if $_[0]; 999 or return $grp->result ();
870 my $now = time;
871 my $hash1 = join ":", (stat _)[0,1,3,7,9];
872 1000
873 # read the directory entries 1001 my $wd = [shift, "."];
1002
1003 # stat once
874 aioreq_pri $pri; 1004 aioreq_pri $pri;
875 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { 1005 add $grp aio_stat $wd, sub {
876 my $entries = shift
877 or return $grp->result (); 1006 return $grp->result () if $_[0];
1007 my $now = time;
1008 my $hash1 = join ":", (stat _)[0,1,3,7,9];
878 1009
879 # stat the dir another time 1010 # read the directory entries
880 aioreq_pri $pri; 1011 aioreq_pri $pri;
1012 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
1013 my $entries = shift
1014 or return $grp->result ();
1015
1016 # stat the dir another time
1017 aioreq_pri $pri;
881 add $grp aio_stat $path, sub { 1018 add $grp aio_stat $wd, sub {
882 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1019 my $hash2 = join ":", (stat _)[0,1,3,7,9];
883 1020
884 my $ndirs; 1021 my $ndirs;
885 1022
886 # take the slow route if anything looks fishy 1023 # take the slow route if anything looks fishy
887 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1024 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
888 $ndirs = -1; 1025 $ndirs = -1;
889 } else { 1026 } else {
890 # if nlink == 2, we are finished 1027 # if nlink == 2, we are finished
891 # for non-posix-fs's, we rely on nlink < 2 1028 # for non-posix-fs's, we rely on nlink < 2
892 $ndirs = (stat _)[3] - 2 1029 $ndirs = (stat _)[3] - 2
893 or return $grp->result ([], $entries); 1030 or return $grp->result ([], $entries);
894 } 1031 }
895 1032
896 my (@dirs, @nondirs); 1033 my (@dirs, @nondirs);
897 1034
898 my $statgrp = add $grp aio_group sub { 1035 my $statgrp = add $grp aio_group sub {
899 $grp->result (\@dirs, \@nondirs); 1036 $grp->result (\@dirs, \@nondirs);
900 }; 1037 };
901 1038
902 limit $statgrp $maxreq; 1039 limit $statgrp $maxreq;
903 feed $statgrp sub { 1040 feed $statgrp sub {
904 return unless @$entries; 1041 return unless @$entries;
905 my $entry = shift @$entries; 1042 my $entry = shift @$entries;
906 1043
907 aioreq_pri $pri; 1044 aioreq_pri $pri;
1045 $wd->[1] = "$entry/.";
908 add $statgrp aio_stat "$path/$entry/.", sub { 1046 add $statgrp aio_stat $wd, sub {
909 if ($_[0] < 0) { 1047 if ($_[0] < 0) {
910 push @nondirs, $entry; 1048 push @nondirs, $entry;
911 } else { 1049 } else {
912 # need to check for real directory 1050 # need to check for real directory
913 aioreq_pri $pri; 1051 aioreq_pri $pri;
1052 $wd->[1] = $entry;
914 add $statgrp aio_lstat "$path/$entry", sub { 1053 add $statgrp aio_lstat $wd, sub {
915 if (-d _) { 1054 if (-d _) {
916 push @dirs, $entry; 1055 push @dirs, $entry;
917 1056
918 unless (--$ndirs) { 1057 unless (--$ndirs) {
919 push @nondirs, @$entries; 1058 push @nondirs, @$entries;
920 feed $statgrp; 1059 feed $statgrp;
1060 }
1061 } else {
1062 push @nondirs, $entry;
921 } 1063 }
922 } else {
923 push @nondirs, $entry;
924 } 1064 }
925 } 1065 }
926 } 1066 };
927 }; 1067 };
928 }; 1068 };
929 }; 1069 };
930 }; 1070 };
931 }; 1071 };
932 1072
933 $grp 1073 $grp
934} 1074}
935 1075
936=item aio_rmtree $path, $callback->($status) 1076=item aio_rmtree $pathname, $callback->($status)
937 1077
938Delete a directory tree starting (and including) C<$path>, return the 1078Delete a directory tree starting (and including) C<$path>, return the
939status of the final C<rmdir> only. This is a composite request that 1079status of the final C<rmdir> only. This is a composite request that
940uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1080uses C<aio_scandir> to recurse into and rmdir directories, and unlink
941everything else. 1081everything else.
… …
983callback with the fdatasync result code. 1123callback with the fdatasync result code.
984 1124
985If this call isn't available because your OS lacks it or it couldn't be 1125If this call isn't available because your OS lacks it or it couldn't be
986detected, it will be emulated by calling C<fsync> instead. 1126detected, it will be emulated by calling C<fsync> instead.
987 1127
1128=item aio_syncfs $fh, $callback->($status)
1129
1130Asynchronously call the syncfs syscall to sync the filesystem associated
1131to the given filehandle and call the callback with the syncfs result
1132code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1133errno to C<ENOSYS> nevertheless.
1134
988=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1135=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
989 1136
990Sync the data portion of the file specified by C<$offset> and C<$length> 1137Sync the data portion of the file specified by C<$offset> and C<$length>
991to disk (but NOT the metadata), by calling the Linux-specific 1138to disk (but NOT the metadata), by calling the Linux-specific
992sync_file_range call. If sync_file_range is not available or it returns 1139sync_file_range call. If sync_file_range is not available or it returns
… …
995C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, 1142C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
996C<IO::AIO::SYNC_FILE_RANGE_WRITE> and 1143C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
997C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range 1144C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
998manpage for details. 1145manpage for details.
999 1146
1000=item aio_pathsync $path, $callback->($status) 1147=item aio_pathsync $pathname, $callback->($status)
1001 1148
1002This request tries to open, fsync and close the given path. This is a 1149This request tries to open, fsync and close the given path. This is a
1003composite request intended to sync directories after directory operations 1150composite request intended to sync directories after directory operations
1004(E.g. rename). This might not work on all operating systems or have any 1151(E.g. rename). This might not work on all operating systems or have any
1005specific effect, but usually it makes sure that directory changes get 1152specific effect, but usually it makes sure that directory changes get
… …
1039} 1186}
1040 1187
1041=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1188=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1042 1189
1043This is a rather advanced IO::AIO call, which only works on mmap(2)ed 1190This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1044scalars (see the L<Sys::Mmap> or L<Mmap> modules for details on this, note 1191scalars (see the C<IO::AIO::mmap> function, although it also works on data
1192scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1045that the scalar must only be modified in-place while an aio operation is 1193scalar must only be modified in-place while an aio operation is pending on
1046pending on it). 1194it).
1047 1195
1048It calls the C<msync> function of your OS, if available, with the memory 1196It calls the C<msync> function of your OS, if available, with the memory
1049area starting at C<$offset> in the string and ending C<$length> bytes 1197area starting at C<$offset> in the string and ending C<$length> bytes
1050later. If C<$length> is negative, counts from the end, and if C<$length> 1198later. If C<$length> is negative, counts from the end, and if C<$length>
1051is C<undef>, then it goes till the end of the string. The flags can be 1199is C<undef>, then it goes till the end of the string. The flags can be
… …
1062as for C<aio_msync>, above, except for flags, which must be either 1210as for C<aio_msync>, above, except for flags, which must be either
1063C<0> (which reads all pages and ensures they are instantiated) or 1211C<0> (which reads all pages and ensures they are instantiated) or
1064C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and 1212C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
1065writing an octet from it, which dirties the page). 1213writing an octet from it, which dirties the page).
1066 1214
1215=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1216
1217This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1218scalars.
1219
1220It reads in all the pages of the underlying storage into memory (if any)
1221and locks them, so they are not getting swapped/paged out or removed.
1222
1223If C<$length> is undefined, then the scalar will be locked till the end.
1224
1225On systems that do not implement C<mlock>, this function returns C<-1>
1226and sets errno to C<ENOSYS>.
1227
1228Note that the corresponding C<munlock> is synchronous and is
1229documented under L<MISCELLANEOUS FUNCTIONS>.
1230
1231Example: open a file, mmap and mlock it - both will be undone when
1232C<$data> gets destroyed.
1233
1234 open my $fh, "<", $path or die "$path: $!";
1235 my $data;
1236 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1237 aio_mlock $data; # mlock in background
1238
1239=item aio_mlockall $flags, $callback->($status)
1240
1241Calls the C<mlockall> function with the given C<$flags> (a combination of
1242C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1243
1244On systems that do not implement C<mlockall>, this function returns C<-1>
1245and sets errno to C<ENOSYS>.
1246
1247Note that the corresponding C<munlockall> is synchronous and is
1248documented under L<MISCELLANEOUS FUNCTIONS>.
1249
1250Example: asynchronously lock all current and future pages into memory.
1251
1252 aio_mlockall IO::AIO::MCL_FUTURE;
1253
1067=item aio_group $callback->(...) 1254=item aio_group $callback->(...)
1068 1255
1069This is a very special aio request: Instead of doing something, it is a 1256This is a very special aio request: Instead of doing something, it is a
1070container for other aio requests, which is useful if you want to bundle 1257container for other aio requests, which is useful if you want to bundle
1071many requests into a single, composite, request with a definite callback 1258many requests into a single, composite, request with a definite callback
… …
1107like sleep and file handle readable/writable, the overhead this creates is 1294like sleep and file handle readable/writable, the overhead this creates is
1108immense (it blocks a thread for a long time) so do not use this function 1295immense (it blocks a thread for a long time) so do not use this function
1109except to put your application under artificial I/O pressure. 1296except to put your application under artificial I/O pressure.
1110 1297
1111=back 1298=back
1299
1300
1301=head2 IO::AIO::WD - multiple working directories
1302
1303Your process only has one current working directory, which is used by all
1304threads. This makes it hard to use relative paths (some other component
1305could call C<chdir> at any time, and it is hard to control when the path
1306will be used by IO::AIO).
1307
1308One solution for this is to always use absolute paths. This usually works,
1309but can be quite slow (the kernel has to walk the whole path on every
1310access), and can also be a hassle to implement.
1311
1312Newer POSIX systems have a number of functions (openat, fdopendir,
1313futimensat and so on) that make it possible to specify working directories
1314per operation.
1315
1316For portability, and because the clowns who "designed", or shall I write,
1317perpetrated this new interface were obviously half-drunk, this abstraction
1318cannot be perfect, though.
1319
1320IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1321object. This object stores the canonicalised, absolute version of the
1322path, and on systems that allow it, also a directory file descriptor.
1323
1324Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1325or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1326object and a pathname instead (or the IO::AIO::WD object alone, which
1327gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1328IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1329to that IO::AIO::WD object.
1330
1331For example, to get a wd object for F</etc> and then stat F<passwd>
1332inside, you would write:
1333
1334 aio_wd "/etc", sub {
1335 my $etcdir = shift;
1336
1337 # although $etcdir can be undef on error, there is generally no reason
1338 # to check for errors here, as aio_stat will fail with ENOENT
1339 # when $etcdir is undef.
1340
1341 aio_stat [$etcdir, "passwd"], sub {
1342 # yay
1343 };
1344 };
1345
1346That C<aio_wd> is a request and not a normal function shows that creating
1347an IO::AIO::WD object is itself a potentially blocking operation, which is
1348why it is done asynchronously.
1349
1350To stat the directory obtained with C<aio_wd> above, one could write
1351either of the following three request calls:
1352
1353 aio_lstat "/etc" , sub { ... # pathname as normal string
1354 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1355 aio_lstat $wd , sub { ... # shorthand for the previous
1356
1357As with normal pathnames, IO::AIO keeps a copy of the working directory
1358object and the pathname string, so you could write the following without
1359causing any issues due to C<$path> getting reused:
1360
1361 my $path = [$wd, undef];
1362
1363 for my $name (qw(abc def ghi)) {
1364 $path->[1] = $name;
1365 aio_stat $path, sub {
1366 # ...
1367 };
1368 }
1369
1370There are some caveats: when directories get renamed (or deleted), the
1371pathname string doesn't change, so will point to the new directory (or
1372nowhere at all), while the directory fd, if available on the system,
1373will still point to the original directory. Most functions accepting a
1374pathname will use the directory fd on newer systems, and the string on
1375older systems. Some functions (such as realpath) will always rely on the
1376string form of the pathname.
1377
1378So this fucntionality is mainly useful to get some protection against
1379C<chdir>, to easily get an absolute path out of a relative path for future
1380reference, and to speed up doing many operations in the same directory
1381(e.g. when stat'ing all files in a directory).
1382
1383The following functions implement this working directory abstraction:
1384
1385=over 4
1386
1387=item aio_wd $pathname, $callback->($wd)
1388
1389Asynchonously canonicalise the given pathname and convert it to an
1390IO::AIO::WD object representing it. If possible and supported on the
1391system, also open a directory fd to speed up pathname resolution relative
1392to this working directory.
1393
1394If something goes wrong, then C<undef> is passwd to the callback instead
1395of a working directory object and C<$!> is set appropriately. Since
1396passing C<undef> as working directory component of a pathname fails the
1397request with C<ENOENT>, there is often no need for error checking in the
1398C<aio_wd> callback, as future requests using the value will fail in the
1399expected way.
1400
1401If this call isn't available because your OS lacks it or it couldn't be
1402detected, it will be emulated by calling C<fsync> instead.
1403
1404=item IO::AIO::CWD
1405
1406This is a compiletime constant (object) that represents the process
1407current working directory.
1408
1409Specifying this object as working directory object for a pathname is as
1410if the pathname would be specified directly, without a directory object,
1411e.g., these calls are functionally identical:
1412
1413 aio_stat "somefile", sub { ... };
1414 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1415
1416=back
1417
1112 1418
1113=head2 IO::AIO::REQ CLASS 1419=head2 IO::AIO::REQ CLASS
1114 1420
1115All non-aggregate C<aio_*> functions return an object of this class when 1421All non-aggregate C<aio_*> functions return an object of this class when
1116called in non-void context. 1422called in non-void context.
… …
1234 1540
1235Sets a feeder/generator on this group: every group can have an attached 1541Sets a feeder/generator on this group: every group can have an attached
1236generator that generates requests if idle. The idea behind this is that, 1542generator that generates requests if idle. The idea behind this is that,
1237although you could just queue as many requests as you want in a group, 1543although you could just queue as many requests as you want in a group,
1238this might starve other requests for a potentially long time. For example, 1544this might starve other requests for a potentially long time. For example,
1239C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, 1545C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1240delaying any later requests for a long time. 1546requests, delaying any later requests for a long time.
1241 1547
1242To avoid this, and allow incremental generation of requests, you can 1548To avoid this, and allow incremental generation of requests, you can
1243instead a group and set a feeder on it that generates those requests. The 1549instead a group and set a feeder on it that generates those requests. The
1244feed callback will be called whenever there are few enough (see C<limit>, 1550feed callback will be called whenever there are few enough (see C<limit>,
1245below) requests active in the group itself and is expected to queue more 1551below) requests active in the group itself and is expected to queue more
… …
1294 1600
1295See C<poll_cb> for an example. 1601See C<poll_cb> for an example.
1296 1602
1297=item IO::AIO::poll_cb 1603=item IO::AIO::poll_cb
1298 1604
1299Process some outstanding events on the result pipe. You have to call this 1605Process some outstanding events on the result pipe. You have to call
1300regularly. Returns C<0> if all events could be processed, or C<-1> if it 1606this regularly. Returns C<0> if all events could be processed (or there
1301returned earlier for whatever reason. Returns immediately when no events 1607were no events to process), or C<-1> if it returned earlier for whatever
1302are outstanding. The amount of events processed depends on the settings of 1608reason. Returns immediately when no events are outstanding. The amount of
1303C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1609events processed depends on the settings of C<IO::AIO::max_poll_req> and
1610C<IO::AIO::max_poll_time>.
1304 1611
1305If not all requests were processed for whatever reason, the filehandle 1612If not all requests were processed for whatever reason, the filehandle
1306will still be ready when C<poll_cb> returns, so normally you don't have to 1613will still be ready when C<poll_cb> returns, so normally you don't have to
1307do anything special to have it called later. 1614do anything special to have it called later.
1308 1615
1616Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1617ready, it can be beneficial to call this function from loops which submit
1618a lot of requests, to make sure the results get processed when they become
1619available and not just when the loop is finished and the event loop takes
1620over again. This function returns very fast when there are no outstanding
1621requests.
1622
1309Example: Install an Event watcher that automatically calls 1623Example: Install an Event watcher that automatically calls
1310IO::AIO::poll_cb with high priority (more examples can be found in the 1624IO::AIO::poll_cb with high priority (more examples can be found in the
1311SYNOPSIS section, at the top of this document): 1625SYNOPSIS section, at the top of this document):
1312 1626
1313 Event->io (fd => IO::AIO::poll_fileno, 1627 Event->io (fd => IO::AIO::poll_fileno,
1314 poll => 'r', async => 1, 1628 poll => 'r', async => 1,
1315 cb => \&IO::AIO::poll_cb); 1629 cb => \&IO::AIO::poll_cb);
1630
1631=item IO::AIO::poll_wait
1632
1633If there are any outstanding requests and none of them in the result
1634phase, wait till the result filehandle becomes ready for reading (simply
1635does a C<select> on the filehandle. This is useful if you want to
1636synchronously wait for some requests to finish).
1637
1638See C<nreqs> for an example.
1639
1640=item IO::AIO::poll
1641
1642Waits until some requests have been handled.
1643
1644Returns the number of requests processed, but is otherwise strictly
1645equivalent to:
1646
1647 IO::AIO::poll_wait, IO::AIO::poll_cb
1648
1649=item IO::AIO::flush
1650
1651Wait till all outstanding AIO requests have been handled.
1652
1653Strictly equivalent to:
1654
1655 IO::AIO::poll_wait, IO::AIO::poll_cb
1656 while IO::AIO::nreqs;
1316 1657
1317=item IO::AIO::max_poll_reqs $nreqs 1658=item IO::AIO::max_poll_reqs $nreqs
1318 1659
1319=item IO::AIO::max_poll_time $seconds 1660=item IO::AIO::max_poll_time $seconds
1320 1661
… …
1345 # use a low priority so other tasks have priority 1686 # use a low priority so other tasks have priority
1346 Event->io (fd => IO::AIO::poll_fileno, 1687 Event->io (fd => IO::AIO::poll_fileno,
1347 poll => 'r', nice => 1, 1688 poll => 'r', nice => 1,
1348 cb => &IO::AIO::poll_cb); 1689 cb => &IO::AIO::poll_cb);
1349 1690
1350=item IO::AIO::poll_wait
1351
1352If there are any outstanding requests and none of them in the result
1353phase, wait till the result filehandle becomes ready for reading (simply
1354does a C<select> on the filehandle. This is useful if you want to
1355synchronously wait for some requests to finish).
1356
1357See C<nreqs> for an example.
1358
1359=item IO::AIO::poll
1360
1361Waits until some requests have been handled.
1362
1363Returns the number of requests processed, but is otherwise strictly
1364equivalent to:
1365
1366 IO::AIO::poll_wait, IO::AIO::poll_cb
1367
1368=item IO::AIO::flush
1369
1370Wait till all outstanding AIO requests have been handled.
1371
1372Strictly equivalent to:
1373
1374 IO::AIO::poll_wait, IO::AIO::poll_cb
1375 while IO::AIO::nreqs;
1376
1377=back 1691=back
1378 1692
1379=head3 CONTROLLING THE NUMBER OF THREADS 1693=head3 CONTROLLING THE NUMBER OF THREADS
1380 1694
1381=over 1695=over
… …
1414 1728
1415Under normal circumstances you don't need to call this function. 1729Under normal circumstances you don't need to call this function.
1416 1730
1417=item IO::AIO::max_idle $nthreads 1731=item IO::AIO::max_idle $nthreads
1418 1732
1419Limit the number of threads (default: 4) that are allowed to idle (i.e., 1733Limit the number of threads (default: 4) that are allowed to idle
1420threads that did not get a request to process within 10 seconds). That 1734(i.e., threads that did not get a request to process within the idle
1421means if a thread becomes idle while C<$nthreads> other threads are also 1735timeout (default: 10 seconds). That means if a thread becomes idle while
1422idle, it will free its resources and exit. 1736C<$nthreads> other threads are also idle, it will free its resources and
1737exit.
1423 1738
1424This is useful when you allow a large number of threads (e.g. 100 or 1000) 1739This is useful when you allow a large number of threads (e.g. 100 or 1000)
1425to allow for extremely high load situations, but want to free resources 1740to allow for extremely high load situations, but want to free resources
1426under normal circumstances (1000 threads can easily consume 30MB of RAM). 1741under normal circumstances (1000 threads can easily consume 30MB of RAM).
1427 1742
1428The default is probably ok in most situations, especially if thread 1743The default is probably ok in most situations, especially if thread
1429creation is fast. If thread creation is very slow on your system you might 1744creation is fast. If thread creation is very slow on your system you might
1430want to use larger values. 1745want to use larger values.
1431 1746
1747=item IO::AIO::idle_timeout $seconds
1748
1749Sets the minimum idle timeout (default 10) after which worker threads are
1750allowed to exit. SEe C<IO::AIO::max_idle>.
1751
1432=item IO::AIO::max_outstanding $maxreqs 1752=item IO::AIO::max_outstanding $maxreqs
1753
1754Sets the maximum number of outstanding requests to C<$nreqs>. If
1755you do queue up more than this number of requests, the next call to
1756C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1757C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1758longer exceeded.
1759
1760In other words, this setting does not enforce a queue limit, but can be
1761used to make poll functions block if the limit is exceeded.
1433 1762
1434This is a very bad function to use in interactive programs because it 1763This is a very bad function to use in interactive programs because it
1435blocks, and a bad way to reduce concurrency because it is inexact: Better 1764blocks, and a bad way to reduce concurrency because it is inexact: Better
1436use an C<aio_group> together with a feed callback. 1765use an C<aio_group> together with a feed callback.
1437 1766
1438Sets the maximum number of outstanding requests to C<$nreqs>. If you 1767It's main use is in scripts without an event loop - when you want to stat
1439do queue up more than this number of requests, the next call to the 1768a lot of files, you can write somehting like this:
1440C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1441function will block until the limit is no longer exceeded.
1442 1769
1443The default value is very large, so there is no practical limit on the 1770 IO::AIO::max_outstanding 32;
1444number of outstanding requests.
1445 1771
1446You can still queue as many requests as you want. Therefore, 1772 for my $path (...) {
1447C<max_outstanding> is mainly useful in simple scripts (with low values) or 1773 aio_stat $path , ...;
1448as a stop gap to shield against fatal memory overflow (with large values). 1774 IO::AIO::poll_cb;
1775 }
1776
1777 IO::AIO::flush;
1778
1779The call to C<poll_cb> inside the loop will normally return instantly, but
1780as soon as more thna C<32> reqeusts are in-flight, it will block until
1781some requests have been handled. This keeps the loop from pushing a large
1782number of C<aio_stat> requests onto the queue.
1783
1784The default value for C<max_outstanding> is very large, so there is no
1785practical limit on the number of outstanding requests.
1449 1786
1450=back 1787=back
1451 1788
1452=head3 STATISTICAL INFORMATION 1789=head3 STATISTICAL INFORMATION
1453 1790
… …
1491 1828
1492Returns the number of bytes copied, or C<-1> on error. 1829Returns the number of bytes copied, or C<-1> on error.
1493 1830
1494=item IO::AIO::fadvise $fh, $offset, $len, $advice 1831=item IO::AIO::fadvise $fh, $offset, $len, $advice
1495 1832
1496Simply calls the C<posix_fadvise> function (see it's 1833Simply calls the C<posix_fadvise> function (see its
1497manpage for details). The following advice constants are 1834manpage for details). The following advice constants are
1498avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>, 1835available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1499C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>, 1836C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1500C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>. 1837C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1501 1838
1502On systems that do not implement C<posix_fadvise>, this function returns 1839On systems that do not implement C<posix_fadvise>, this function returns
1503ENOSYS, otherwise the return value of C<posix_fadvise>. 1840ENOSYS, otherwise the return value of C<posix_fadvise>.
1504 1841
1842=item IO::AIO::madvise $scalar, $offset, $len, $advice
1843
1844Simply calls the C<posix_madvise> function (see its
1845manpage for details). The following advice constants are
1846available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1847C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1848
1849On systems that do not implement C<posix_madvise>, this function returns
1850ENOSYS, otherwise the return value of C<posix_madvise>.
1851
1852=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1853
1854Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1855$scalar (see its manpage for details). The following protect
1856constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1857C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1858
1859On systems that do not implement C<mprotect>, this function returns
1860ENOSYS, otherwise the return value of C<mprotect>.
1861
1862=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1863
1864Memory-maps a file (or anonymous memory range) and attaches it to the
1865given C<$scalar>, which will act like a string scalar.
1866
1867The only operations allowed on the scalar are C<substr>/C<vec> that don't
1868change the string length, and most read-only operations such as copying it
1869or searching it with regexes and so on.
1870
1871Anything else is unsafe and will, at best, result in memory leaks.
1872
1873The memory map associated with the C<$scalar> is automatically removed
1874when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
1875C<IO::AIO::munmap> functions are called.
1876
1877This calls the C<mmap>(2) function internally. See your system's manual
1878page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1879
1880The C<$length> must be larger than zero and smaller than the actual
1881filesize.
1882
1883C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1884C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1885
1886C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
1887C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
1888not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
1889(which is set to C<MAP_ANON> if your system only provides this
1890constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
1891C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1892C<IO::AIO::MAP_NONBLOCK>
1893
1894If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1895
1896C<$offset> is the offset from the start of the file - it generally must be
1897a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1898
1899Example:
1900
1901 use Digest::MD5;
1902 use IO::AIO;
1903
1904 open my $fh, "<verybigfile"
1905 or die "$!";
1906
1907 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1908 or die "verybigfile: $!";
1909
1910 my $fast_md5 = md5 $data;
1911
1912=item IO::AIO::munmap $scalar
1913
1914Removes a previous mmap and undefines the C<$scalar>.
1915
1916=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1917
1918Calls the C<munlock> function, undoing the effects of a previous
1919C<aio_mlock> call (see its description for details).
1920
1921=item IO::AIO::munlockall
1922
1923Calls the C<munlockall> function.
1924
1925On systems that do not implement C<munlockall>, this function returns
1926ENOSYS, otherwise the return value of C<munlockall>.
1927
1505=back 1928=back
1506 1929
1507=cut 1930=cut
1508 1931
1509min_parallel 8; 1932min_parallel 8;
1510 1933
1511END { flush } 1934END { flush }
1512 1935
15131; 19361;
1514 1937
1938=head1 EVENT LOOP INTEGRATION
1939
1940It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
1941automatically into many event loops:
1942
1943 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1944 use AnyEvent::AIO;
1945
1946You can also integrate IO::AIO manually into many event loops, here are
1947some examples of how to do this:
1948
1949 # EV integration
1950 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1951
1952 # Event integration
1953 Event->io (fd => IO::AIO::poll_fileno,
1954 poll => 'r',
1955 cb => \&IO::AIO::poll_cb);
1956
1957 # Glib/Gtk2 integration
1958 add_watch Glib::IO IO::AIO::poll_fileno,
1959 in => sub { IO::AIO::poll_cb; 1 };
1960
1961 # Tk integration
1962 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1963 readable => \&IO::AIO::poll_cb);
1964
1965 # Danga::Socket integration
1966 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1967 \&IO::AIO::poll_cb);
1968
1515=head2 FORK BEHAVIOUR 1969=head2 FORK BEHAVIOUR
1516 1970
1517This module should do "the right thing" when the process using it forks: 1971Usage of pthreads in a program changes the semantics of fork
1972considerably. Specifically, only async-safe functions can be called after
1973fork. Perl doesn't know about this, so in general, you cannot call fork
1974with defined behaviour in perl if pthreads are involved. IO::AIO uses
1975pthreads, so this applies, but many other extensions and (for inexplicable
1976reasons) perl itself often is linked against pthreads, so this limitation
1977applies to quite a lot of perls.
1518 1978
1519Before the fork, IO::AIO enters a quiescent state where no requests 1979This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1520can be added in other threads and no results will be processed. After 1980only works in the process that loaded it. Forking is fully supported, but
1521the fork the parent simply leaves the quiescent state and continues 1981using IO::AIO in the child is not.
1522request/result processing, while the child frees the request/result queue
1523(so that the requests started before the fork will only be handled in the
1524parent). Threads will be started on demand until the limit set in the
1525parent process has been reached again.
1526 1982
1527In short: the parent will, after a short pause, continue as if fork had 1983You might get around by not I<using> IO::AIO before (or after)
1528not been called, while the child will act as if IO::AIO has not been used 1984forking. You could also try to call the L<IO::AIO::reinit> function in the
1529yet. 1985child:
1986
1987=over 4
1988
1989=item IO::AIO::reinit
1990
1991Abandons all current requests and I/O threads and simply reinitialises all
1992data structures. This is not an operation supported by any standards, but
1993happens to work on GNU/Linux and some newer BSD systems.
1994
1995The only reasonable use for this function is to call it after forking, if
1996C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
1997the process will result in undefined behaviour. Calling it at any time
1998will also result in any undefined (by POSIX) behaviour.
1999
2000=back
1530 2001
1531=head2 MEMORY USAGE 2002=head2 MEMORY USAGE
1532 2003
1533Per-request usage: 2004Per-request usage:
1534 2005

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