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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.195 by root, Fri May 27 19:56:31 2011 UTC vs.
Revision 1.258 by root, Thu Jan 21 23:04:46 2016 UTC

68=head2 EXAMPLE 68=head2 EXAMPLE
69 69
70This is a simple example that uses the EV module and loads 70This is a simple example that uses the EV module and loads
71F</etc/passwd> asynchronously: 71F</etc/passwd> asynchronously:
72 72
73 use Fcntl;
74 use EV; 73 use EV;
75 use IO::AIO; 74 use IO::AIO;
76 75
77 # register the IO::AIO callback with EV 76 # register the IO::AIO callback with EV
78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 77 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
95 94
96 # file contents now in $contents 95 # file contents now in $contents
97 print $contents; 96 print $contents;
98 97
99 # exit event loop and program 98 # exit event loop and program
100 EV::unloop; 99 EV::break;
101 }; 100 };
102 }; 101 };
103 102
104 # possibly queue up other requests, or open GUI windows, 103 # possibly queue up other requests, or open GUI windows,
105 # check for sockets etc. etc. 104 # check for sockets etc. etc.
106 105
107 # process events as long as there are some: 106 # process events as long as there are some:
108 EV::loop; 107 EV::run;
109 108
110=head1 REQUEST ANATOMY AND LIFETIME 109=head1 REQUEST ANATOMY AND LIFETIME
111 110
112Every C<aio_*> function creates a request. which is a C data structure not 111Every C<aio_*> function creates a request. which is a C data structure not
113directly visible to Perl. 112directly visible to Perl.
168use common::sense; 167use common::sense;
169 168
170use base 'Exporter'; 169use base 'Exporter';
171 170
172BEGIN { 171BEGIN {
173 our $VERSION = '3.9'; 172 our $VERSION = 4.33;
174 173
175 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 174 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx 175 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync 176 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
178 aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead 177 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_allocate
178 aio_pathsync aio_readahead aio_fiemap
179 aio_rename aio_link aio_move aio_copy aio_group 179 aio_rename aio_link aio_move aio_copy aio_group
180 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 180 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
181 aio_chmod aio_utime aio_truncate 181 aio_chmod aio_utime aio_truncate
182 aio_msync aio_mtouch aio_mlock aio_mlockall 182 aio_msync aio_mtouch aio_mlock aio_mlockall
183 aio_statvfs); 183 aio_statvfs
184 aio_wd);
184 185
185 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 186 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
186 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 187 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
187 min_parallel max_parallel max_idle idle_timeout 188 min_parallel max_parallel max_idle idle_timeout
188 nreqs nready npending nthreads 189 nreqs nready npending nthreads
200 201
201=head1 FUNCTIONS 202=head1 FUNCTIONS
202 203
203=head2 QUICK OVERVIEW 204=head2 QUICK OVERVIEW
204 205
205This section simply lists the prototypes of the most important functions 206This section simply lists the prototypes most of the functions for
206for quick reference. See the following sections for function-by-function 207quick reference. See the following sections for function-by-function
207documentation. 208documentation.
208 209
210 aio_wd $pathname, $callback->($wd)
209 aio_open $pathname, $flags, $mode, $callback->($fh) 211 aio_open $pathname, $flags, $mode, $callback->($fh)
210 aio_close $fh, $callback->($status) 212 aio_close $fh, $callback->($status)
213 aio_seek $fh,$offset,$whence, $callback->($offs)
211 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 214 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 215 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 216 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214 aio_readahead $fh,$offset,$length, $callback->($retval) 217 aio_readahead $fh,$offset,$length, $callback->($retval)
215 aio_stat $fh_or_path, $callback->($status) 218 aio_stat $fh_or_path, $callback->($status)
216 aio_lstat $fh, $callback->($status) 219 aio_lstat $fh, $callback->($status)
217 aio_statvfs $fh_or_path, $callback->($statvfs) 220 aio_statvfs $fh_or_path, $callback->($statvfs)
218 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 221 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 222 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
223 aio_chmod $fh_or_path, $mode, $callback->($status)
220 aio_truncate $fh_or_path, $offset, $callback->($status) 224 aio_truncate $fh_or_path, $offset, $callback->($status)
221 aio_chmod $fh_or_path, $mode, $callback->($status) 225 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
226 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
222 aio_unlink $pathname, $callback->($status) 227 aio_unlink $pathname, $callback->($status)
223 aio_mknod $path, $mode, $dev, $callback->($status) 228 aio_mknod $pathname, $mode, $dev, $callback->($status)
224 aio_link $srcpath, $dstpath, $callback->($status) 229 aio_link $srcpath, $dstpath, $callback->($status)
225 aio_symlink $srcpath, $dstpath, $callback->($status) 230 aio_symlink $srcpath, $dstpath, $callback->($status)
226 aio_readlink $path, $callback->($link) 231 aio_readlink $pathname, $callback->($link)
232 aio_realpath $pathname, $callback->($path)
227 aio_rename $srcpath, $dstpath, $callback->($status) 233 aio_rename $srcpath, $dstpath, $callback->($status)
228 aio_mkdir $pathname, $mode, $callback->($status) 234 aio_mkdir $pathname, $mode, $callback->($status)
229 aio_rmdir $pathname, $callback->($status) 235 aio_rmdir $pathname, $callback->($status)
230 aio_readdir $pathname, $callback->($entries) 236 aio_readdir $pathname, $callback->($entries)
231 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 237 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 238 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 239 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
240 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
234 aio_load $path, $data, $callback->($status) 241 aio_load $pathname, $data, $callback->($status)
235 aio_copy $srcpath, $dstpath, $callback->($status) 242 aio_copy $srcpath, $dstpath, $callback->($status)
236 aio_move $srcpath, $dstpath, $callback->($status) 243 aio_move $srcpath, $dstpath, $callback->($status)
237 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238 aio_rmtree $path, $callback->($status) 244 aio_rmtree $pathname, $callback->($status)
239 aio_sync $callback->($status) 245 aio_sync $callback->($status)
246 aio_syncfs $fh, $callback->($status)
240 aio_fsync $fh, $callback->($status) 247 aio_fsync $fh, $callback->($status)
241 aio_fdatasync $fh, $callback->($status) 248 aio_fdatasync $fh, $callback->($status)
242 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 249 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243 aio_pathsync $path, $callback->($status) 250 aio_pathsync $pathname, $callback->($status)
244 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 251 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
245 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 252 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 253 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247 aio_mlockall $flags, $callback->($status) 254 aio_mlockall $flags, $callback->($status)
248 aio_group $callback->(...) 255 aio_group $callback->(...)
266 IO::AIO::nready 273 IO::AIO::nready
267 IO::AIO::npending 274 IO::AIO::npending
268 275
269 IO::AIO::sendfile $ofh, $ifh, $offset, $count 276 IO::AIO::sendfile $ofh, $ifh, $offset, $count
270 IO::AIO::fadvise $fh, $offset, $len, $advice 277 IO::AIO::fadvise $fh, $offset, $len, $advice
278 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
279 IO::AIO::munmap $scalar
271 IO::AIO::madvise $scalar, $offset, $length, $advice 280 IO::AIO::madvise $scalar, $offset, $length, $advice
272 IO::AIO::mprotect $scalar, $offset, $length, $protect 281 IO::AIO::mprotect $scalar, $offset, $length, $protect
273 IO::AIO::munlock $scalar, $offset = 0, $length = undef 282 IO::AIO::munlock $scalar, $offset = 0, $length = undef
274 IO::AIO::munlockall 283 IO::AIO::munlockall
275 284
276=head2 AIO REQUEST FUNCTIONS 285=head2 API NOTES
277 286
278All the C<aio_*> calls are more or less thin wrappers around the syscall 287All the C<aio_*> calls are more or less thin wrappers around the syscall
279with the same name (sans C<aio_>). The arguments are similar or identical, 288with the same name (sans C<aio_>). The arguments are similar or identical,
280and they all accept an additional (and optional) C<$callback> argument 289and they all accept an additional (and optional) C<$callback> argument
281which must be a code reference. This code reference will get called with 290which must be a code reference. This code reference will be called after
282the syscall return code (e.g. most syscalls return C<-1> on error, unlike 291the syscall has been executed in an asynchronous fashion. The results
283perl, which usually delivers "false") as its sole argument after the given 292of the request will be passed as arguments to the callback (and, if an
284syscall has been executed asynchronously. 293error occured, in C<$!>) - for most requests the syscall return code (e.g.
294most syscalls return C<-1> on error, unlike perl, which usually delivers
295"false").
296
297Some requests (such as C<aio_readdir>) pass the actual results and
298communicate failures by passing C<undef>.
285 299
286All functions expecting a filehandle keep a copy of the filehandle 300All functions expecting a filehandle keep a copy of the filehandle
287internally until the request has finished. 301internally until the request has finished.
288 302
289All functions return request objects of type L<IO::AIO::REQ> that allow 303All functions return request objects of type L<IO::AIO::REQ> that allow
290further manipulation of those requests while they are in-flight. 304further manipulation of those requests while they are in-flight.
291 305
292The pathnames you pass to these routines I<must> be absolute and 306The pathnames you pass to these routines I<should> be absolute. The
293encoded as octets. The reason for the former is that at the time the 307reason for this is that at the time the request is being executed, the
294request is being executed, the current working directory could have 308current working directory could have changed. Alternatively, you can
295changed. Alternatively, you can make sure that you never change the 309make sure that you never change the current working directory anywhere
296current working directory anywhere in the program and then use relative 310in the program and then use relative paths. You can also take advantage
297paths. 311of IO::AIOs working directory abstraction, that lets you specify paths
312relative to some previously-opened "working directory object" - see the
313description of the C<IO::AIO::WD> class later in this document.
298 314
299To encode pathnames as octets, either make sure you either: a) always pass 315To encode pathnames as octets, either make sure you either: a) always pass
300in filenames you got from outside (command line, readdir etc.) without 316in filenames you got from outside (command line, readdir etc.) without
301tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 317tinkering, b) are in your native filesystem encoding, c) use the Encode
302your pathnames to the locale (or other) encoding in effect in the user 318module and encode your pathnames to the locale (or other) encoding in
303environment, d) use Glib::filename_from_unicode on unicode filenames or e) 319effect in the user environment, d) use Glib::filename_from_unicode on
304use something else to ensure your scalar has the correct contents. 320unicode filenames or e) use something else to ensure your scalar has the
321correct contents.
305 322
306This works, btw. independent of the internal UTF-8 bit, which IO::AIO 323This works, btw. independent of the internal UTF-8 bit, which IO::AIO
307handles correctly whether it is set or not. 324handles correctly whether it is set or not.
325
326=head2 AIO REQUEST FUNCTIONS
308 327
309=over 4 328=over 4
310 329
311=item $prev_pri = aioreq_pri [$pri] 330=item $prev_pri = aioreq_pri [$pri]
312 331
342 361
343 362
344=item aio_open $pathname, $flags, $mode, $callback->($fh) 363=item aio_open $pathname, $flags, $mode, $callback->($fh)
345 364
346Asynchronously open or create a file and call the callback with a newly 365Asynchronously open or create a file and call the callback with a newly
347created filehandle for the file. 366created filehandle for the file (or C<undef> in case of an error).
348 367
349The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 368The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
350for an explanation. 369for an explanation.
351 370
352The C<$flags> argument is a bitmask. See the C<Fcntl> module for a 371The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
375following POSIX and non-POSIX constants are available (missing ones on 394following POSIX and non-POSIX constants are available (missing ones on
376your system are, as usual, C<0>): 395your system are, as usual, C<0>):
377 396
378C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>, 397C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
379C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>, 398C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
380C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>. 399C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
381 400
382 401
383=item aio_close $fh, $callback->($status) 402=item aio_close $fh, $callback->($status)
384 403
385Asynchronously close a file and call the callback with the result 404Asynchronously close a file and call the callback with the result
394 413
395Or in other words: the file descriptor will be closed, but it will not be 414Or in other words: the file descriptor will be closed, but it will not be
396free for reuse until the perl filehandle is closed. 415free for reuse until the perl filehandle is closed.
397 416
398=cut 417=cut
418
419=item aio_seek $fh, $offset, $whence, $callback->($offs)
420
421Seeks the filehandle to the new C<$offset>, similarly to perl's
422C<sysseek>. The C<$whence> can use the traditional values (C<0> for
423C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
424C<IO::AIO::SEEK_END>).
425
426The resulting absolute offset will be passed to the callback, or C<-1> in
427case of an error.
428
429In theory, the C<$whence> constants could be different than the
430corresponding values from L<Fcntl>, but perl guarantees they are the same,
431so don't panic.
432
433As a GNU/Linux (and maybe Solaris) extension, also the constants
434C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
435could be found. No guarantees about suitability for use in C<aio_seek> or
436Perl's C<sysseek> can be made though, although I would naively assume they
437"just work".
399 438
400=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 439=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
401 440
402=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 441=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
403 442
436 475
437Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 476Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
438reading at byte offset C<$in_offset>, and starts writing at the current 477reading at byte offset C<$in_offset>, and starts writing at the current
439file offset of C<$out_fh>. Because of that, it is not safe to issue more 478file offset of C<$out_fh>. Because of that, it is not safe to issue more
440than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 479than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
441other. 480other. The same C<$in_fh> works fine though, as this function does not
481move or use the file offset of C<$in_fh>.
442 482
443Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than 483Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
444are written, and there is no way to find out how many bytes have been read 484are written, and there is no way to find out how many more bytes have been
445from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of 485read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
446bytes written to C<$out_fh>. Only if the result value equals C<$length> 486number of bytes written to C<$out_fh>. Only if the result value equals
447one can assume that C<$length> bytes have been read. 487C<$length> one can assume that C<$length> bytes have been read.
448 488
449Unlike with other C<aio_> functions, it makes a lot of sense to use 489Unlike with other C<aio_> functions, it makes a lot of sense to use
450C<aio_sendfile> on non-blocking sockets, as long as one end (typically 490C<aio_sendfile> on non-blocking sockets, as long as one end (typically
451the C<$in_fh>) is a file - the file I/O will then be asynchronous, while 491the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
452the socket I/O will be non-blocking. Note, however, that you can run into 492the socket I/O will be non-blocking. Note, however, that you can run
453a trap where C<aio_sendfile> reads some data with readahead, then fails 493into a trap where C<aio_sendfile> reads some data with readahead, then
454to write all data, and when the socket is ready the next time, the data 494fails to write all data, and when the socket is ready the next time, the
455in the cache is already lost, forcing C<aio_sendfile> to again hit the 495data in the cache is already lost, forcing C<aio_sendfile> to again hit
456disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage 496the disk. Explicit C<aio_read> + C<aio_write> let's you better control
457much better. 497resource usage.
458 498
459This call tries to make use of a native C<sendfile> syscall to provide 499This call tries to make use of a native C<sendfile>-like syscall to
460zero-copy operation. For this to work, C<$out_fh> should refer to a 500provide zero-copy operation. For this to work, C<$out_fh> should refer to
461socket, and C<$in_fh> should refer to an mmap'able file. 501a socket, and C<$in_fh> should refer to an mmap'able file.
462 502
463If a native sendfile cannot be found or it fails with C<ENOSYS>, 503If a native sendfile cannot be found or it fails with C<ENOSYS>,
464C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>, 504C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
465it will be emulated, so you can call C<aio_sendfile> on any type of 505C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
466filehandle regardless of the limitations of the operating system. 506type of filehandle regardless of the limitations of the operating system.
507
508As native sendfile syscalls (as practically any non-POSIX interface hacked
509together in a hurry to improve benchmark numbers) tend to be rather buggy
510on many systems, this implementation tries to work around some known bugs
511in Linux and FreeBSD kernels (probably others, too), but that might fail,
512so you really really should check the return value of C<aio_sendfile> -
513fewre bytes than expected might have been transferred.
467 514
468 515
469=item aio_readahead $fh,$offset,$length, $callback->($retval) 516=item aio_readahead $fh,$offset,$length, $callback->($retval)
470 517
471C<aio_readahead> populates the page cache with data from a file so that 518C<aio_readahead> populates the page cache with data from a file so that
555 namemax => 255, 602 namemax => 255,
556 frsize => 1024, 603 frsize => 1024,
557 fsid => 1810 604 fsid => 1810
558 } 605 }
559 606
607Here is a (likely partial - send me updates!) list of fsid values used by
608Linux - it is safe to hardcode these when C<$^O> is C<linux>:
609
610 0x0000adf5 adfs
611 0x0000adff affs
612 0x5346414f afs
613 0x09041934 anon-inode filesystem
614 0x00000187 autofs
615 0x42465331 befs
616 0x1badface bfs
617 0x42494e4d binfmt_misc
618 0x9123683e btrfs
619 0x0027e0eb cgroupfs
620 0xff534d42 cifs
621 0x73757245 coda
622 0x012ff7b7 coh
623 0x28cd3d45 cramfs
624 0x453dcd28 cramfs-wend (wrong endianness)
625 0x64626720 debugfs
626 0x00001373 devfs
627 0x00001cd1 devpts
628 0x0000f15f ecryptfs
629 0x00414a53 efs
630 0x0000137d ext
631 0x0000ef53 ext2/ext3/ext4
632 0x0000ef51 ext2
633 0xf2f52010 f2fs
634 0x00004006 fat
635 0x65735546 fuseblk
636 0x65735543 fusectl
637 0x0bad1dea futexfs
638 0x01161970 gfs2
639 0x47504653 gpfs
640 0x00004244 hfs
641 0xf995e849 hpfs
642 0x00c0ffee hostfs
643 0x958458f6 hugetlbfs
644 0x2bad1dea inotifyfs
645 0x00009660 isofs
646 0x000072b6 jffs2
647 0x3153464a jfs
648 0x6b414653 k-afs
649 0x0bd00bd0 lustre
650 0x0000137f minix
651 0x0000138f minix 30 char names
652 0x00002468 minix v2
653 0x00002478 minix v2 30 char names
654 0x00004d5a minix v3
655 0x19800202 mqueue
656 0x00004d44 msdos
657 0x0000564c novell
658 0x00006969 nfs
659 0x6e667364 nfsd
660 0x00003434 nilfs
661 0x5346544e ntfs
662 0x00009fa1 openprom
663 0x7461636F ocfs2
664 0x00009fa0 proc
665 0x6165676c pstorefs
666 0x0000002f qnx4
667 0x68191122 qnx6
668 0x858458f6 ramfs
669 0x52654973 reiserfs
670 0x00007275 romfs
671 0x67596969 rpc_pipefs
672 0x73636673 securityfs
673 0xf97cff8c selinux
674 0x0000517b smb
675 0x534f434b sockfs
676 0x73717368 squashfs
677 0x62656572 sysfs
678 0x012ff7b6 sysv2
679 0x012ff7b5 sysv4
680 0x01021994 tmpfs
681 0x15013346 udf
682 0x00011954 ufs
683 0x54190100 ufs byteswapped
684 0x00009fa2 usbdevfs
685 0x01021997 v9fs
686 0xa501fcf5 vxfs
687 0xabba1974 xenfs
688 0x012ff7b4 xenix
689 0x58465342 xfs
690 0x012fd16d xia
560 691
561=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 692=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
562 693
563Works like perl's C<utime> function (including the special case of $atime 694Works like perl's C<utime> function (including the special case of $atime
564and $mtime being undef). Fractional times are supported if the underlying 695and $mtime being undef). Fractional times are supported if the underlying
592=item aio_truncate $fh_or_path, $offset, $callback->($status) 723=item aio_truncate $fh_or_path, $offset, $callback->($status)
593 724
594Works like truncate(2) or ftruncate(2). 725Works like truncate(2) or ftruncate(2).
595 726
596 727
728=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
729
730Allocates or frees disk space according to the C<$mode> argument. See the
731linux C<fallocate> documentation for details.
732
733C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
734space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
735to deallocate a file range.
736
737IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
738(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
739your L<fallocate(2)> manpage).
740
741The file system block size used by C<fallocate> is presumably the
742C<f_bsize> returned by C<statvfs>.
743
744If C<fallocate> isn't available or cannot be emulated (currently no
745emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
746
747
597=item aio_chmod $fh_or_path, $mode, $callback->($status) 748=item aio_chmod $fh_or_path, $mode, $callback->($status)
598 749
599Works like perl's C<chmod> function. 750Works like perl's C<chmod> function.
600 751
601 752
603 754
604Asynchronously unlink (delete) a file and call the callback with the 755Asynchronously unlink (delete) a file and call the callback with the
605result code. 756result code.
606 757
607 758
608=item aio_mknod $path, $mode, $dev, $callback->($status) 759=item aio_mknod $pathname, $mode, $dev, $callback->($status)
609 760
610[EXPERIMENTAL] 761[EXPERIMENTAL]
611 762
612Asynchronously create a device node (or fifo). See mknod(2). 763Asynchronously create a device node (or fifo). See mknod(2).
613 764
614The only (POSIX-) portable way of calling this function is: 765The only (POSIX-) portable way of calling this function is:
615 766
616 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 767 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
617 768
618See C<aio_stat> for info about some potentially helpful extra constants 769See C<aio_stat> for info about some potentially helpful extra constants
619and functions. 770and functions.
620 771
621=item aio_link $srcpath, $dstpath, $callback->($status) 772=item aio_link $srcpath, $dstpath, $callback->($status)
628 779
629Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 780Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
630the path C<$dstpath> and call the callback with the result code. 781the path C<$dstpath> and call the callback with the result code.
631 782
632 783
633=item aio_readlink $path, $callback->($link) 784=item aio_readlink $pathname, $callback->($link)
634 785
635Asynchronously read the symlink specified by C<$path> and pass it to 786Asynchronously read the symlink specified by C<$path> and pass it to
636the callback. If an error occurs, nothing or undef gets passed to the 787the callback. If an error occurs, nothing or undef gets passed to the
637callback. 788callback.
638 789
639 790
791=item aio_realpath $pathname, $callback->($path)
792
793Asynchronously make the path absolute and resolve any symlinks in
794C<$path>. The resulting path only consists of directories (same as
795L<Cwd::realpath>).
796
797This request can be used to get the absolute path of the current working
798directory by passing it a path of F<.> (a single dot).
799
800
640=item aio_rename $srcpath, $dstpath, $callback->($status) 801=item aio_rename $srcpath, $dstpath, $callback->($status)
641 802
642Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 803Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
643rename(2) and call the callback with the result code. 804rename(2) and call the callback with the result code.
805
806On systems that support the AIO::WD working directory abstraction
807natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
808of failing, C<rename> is called on the absolute path of C<$wd>.
644 809
645 810
646=item aio_mkdir $pathname, $mode, $callback->($status) 811=item aio_mkdir $pathname, $mode, $callback->($status)
647 812
648Asynchronously mkdir (create) a directory and call the callback with 813Asynchronously mkdir (create) a directory and call the callback with
653=item aio_rmdir $pathname, $callback->($status) 818=item aio_rmdir $pathname, $callback->($status)
654 819
655Asynchronously rmdir (delete) a directory and call the callback with the 820Asynchronously rmdir (delete) a directory and call the callback with the
656result code. 821result code.
657 822
823On systems that support the AIO::WD working directory abstraction
824natively, the case C<[$wd, "."]> is specialcased - instead of failing,
825C<rmdir> is called on the absolute path of C<$wd>.
826
658 827
659=item aio_readdir $pathname, $callback->($entries) 828=item aio_readdir $pathname, $callback->($entries)
660 829
661Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 830Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
662directory (i.e. opendir + readdir + closedir). The entries will not be 831directory (i.e. opendir + readdir + closedir). The entries will not be
666array-ref with the filenames. 835array-ref with the filenames.
667 836
668 837
669=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) 838=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
670 839
671Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune 840Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
672behaviour and output format. In case of an error, C<$entries> will be 841tune behaviour and output format. In case of an error, C<$entries> will be
673C<undef>. 842C<undef>.
674 843
675The flags are a combination of the following constants, ORed together (the 844The flags are a combination of the following constants, ORed together (the
676flags will also be passed to the callback, possibly modified): 845flags will also be passed to the callback, possibly modified):
677 846
724 893
725=item IO::AIO::READDIR_FOUND_UNKNOWN 894=item IO::AIO::READDIR_FOUND_UNKNOWN
726 895
727This flag should not be set when calling C<aio_readdirx>. Instead, it 896This flag should not be set when calling C<aio_readdirx>. Instead, it
728is being set by C<aio_readdirx>, when any of the C<$type>'s found were 897is being set by C<aio_readdirx>, when any of the C<$type>'s found were
729C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all 898C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
730C<$type>'s are known, which can be used to speed up some algorithms. 899C<$type>'s are known, which can be used to speed up some algorithms.
731 900
732=back 901=back
733 902
734 903
735=item aio_load $path, $data, $callback->($status) 904=item aio_load $pathname, $data, $callback->($status)
736 905
737This is a composite request that tries to fully load the given file into 906This is a composite request that tries to fully load the given file into
738memory. Status is the same as with aio_read. 907memory. Status is the same as with aio_read.
739 908
740=cut 909=cut
862 if ($_[0] && $! == EXDEV) { 1031 if ($_[0] && $! == EXDEV) {
863 aioreq_pri $pri; 1032 aioreq_pri $pri;
864 add $grp aio_copy $src, $dst, sub { 1033 add $grp aio_copy $src, $dst, sub {
865 $grp->result ($_[0]); 1034 $grp->result ($_[0]);
866 1035
867 if (!$_[0]) { 1036 unless ($_[0]) {
868 aioreq_pri $pri; 1037 aioreq_pri $pri;
869 add $grp aio_unlink $src; 1038 add $grp aio_unlink $src;
870 } 1039 }
871 }; 1040 };
872 } else { 1041 } else {
875 }; 1044 };
876 1045
877 $grp 1046 $grp
878} 1047}
879 1048
880=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 1049=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
881 1050
882Scans a directory (similar to C<aio_readdir>) but additionally tries to 1051Scans a directory (similar to C<aio_readdir>) but additionally tries to
883efficiently separate the entries of directory C<$path> into two sets of 1052efficiently separate the entries of directory C<$path> into two sets of
884names, directories you can recurse into (directories), and ones you cannot 1053names, directories you can recurse into (directories), and ones you cannot
885recurse into (everything else, including symlinks to directories). 1054recurse into (everything else, including symlinks to directories).
916Then entries will be sorted into likely directories a non-initial dot 1085Then entries will be sorted into likely directories a non-initial dot
917currently) and likely non-directories (see C<aio_readdirx>). Then every 1086currently) and likely non-directories (see C<aio_readdirx>). Then every
918entry plus an appended C</.> will be C<stat>'ed, likely directories first, 1087entry plus an appended C</.> will be C<stat>'ed, likely directories first,
919in order of their inode numbers. If that succeeds, it assumes that the 1088in order of their inode numbers. If that succeeds, it assumes that the
920entry is a directory or a symlink to directory (which will be checked 1089entry is a directory or a symlink to directory (which will be checked
921seperately). This is often faster than stat'ing the entry itself because 1090separately). This is often faster than stat'ing the entry itself because
922filesystems might detect the type of the entry without reading the inode 1091filesystems might detect the type of the entry without reading the inode
923data (e.g. ext2fs filetype feature), even on systems that cannot return 1092data (e.g. ext2fs filetype feature), even on systems that cannot return
924the filetype information on readdir. 1093the filetype information on readdir.
925 1094
926If the known number of directories (link count - 2) has been reached, the 1095If the known number of directories (link count - 2) has been reached, the
942 1111
943 my $grp = aio_group $cb; 1112 my $grp = aio_group $cb;
944 1113
945 $maxreq = 4 if $maxreq <= 0; 1114 $maxreq = 4 if $maxreq <= 0;
946 1115
947 # stat once 1116 # get a wd object
948 aioreq_pri $pri; 1117 aioreq_pri $pri;
949 add $grp aio_stat $path, sub { 1118 add $grp aio_wd $path, sub {
1119 $_[0]
950 return $grp->result () if $_[0]; 1120 or return $grp->result ();
951 my $now = time;
952 my $hash1 = join ":", (stat _)[0,1,3,7,9];
953 1121
954 # read the directory entries 1122 my $wd = [shift, "."];
1123
1124 # stat once
955 aioreq_pri $pri; 1125 aioreq_pri $pri;
956 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { 1126 add $grp aio_stat $wd, sub {
957 my $entries = shift
958 or return $grp->result (); 1127 return $grp->result () if $_[0];
1128 my $now = time;
1129 my $hash1 = join ":", (stat _)[0,1,3,7,9];
959 1130
960 # stat the dir another time 1131 # read the directory entries
961 aioreq_pri $pri; 1132 aioreq_pri $pri;
1133 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
1134 my $entries = shift
1135 or return $grp->result ();
1136
1137 # stat the dir another time
1138 aioreq_pri $pri;
962 add $grp aio_stat $path, sub { 1139 add $grp aio_stat $wd, sub {
963 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1140 my $hash2 = join ":", (stat _)[0,1,3,7,9];
964 1141
965 my $ndirs; 1142 my $ndirs;
966 1143
967 # take the slow route if anything looks fishy 1144 # take the slow route if anything looks fishy
968 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1145 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
969 $ndirs = -1; 1146 $ndirs = -1;
970 } else { 1147 } else {
971 # if nlink == 2, we are finished 1148 # if nlink == 2, we are finished
972 # for non-posix-fs's, we rely on nlink < 2 1149 # for non-posix-fs's, we rely on nlink < 2
973 $ndirs = (stat _)[3] - 2 1150 $ndirs = (stat _)[3] - 2
974 or return $grp->result ([], $entries); 1151 or return $grp->result ([], $entries);
975 } 1152 }
976 1153
977 my (@dirs, @nondirs); 1154 my (@dirs, @nondirs);
978 1155
979 my $statgrp = add $grp aio_group sub { 1156 my $statgrp = add $grp aio_group sub {
980 $grp->result (\@dirs, \@nondirs); 1157 $grp->result (\@dirs, \@nondirs);
981 }; 1158 };
982 1159
983 limit $statgrp $maxreq; 1160 limit $statgrp $maxreq;
984 feed $statgrp sub { 1161 feed $statgrp sub {
985 return unless @$entries; 1162 return unless @$entries;
986 my $entry = shift @$entries; 1163 my $entry = shift @$entries;
987 1164
988 aioreq_pri $pri; 1165 aioreq_pri $pri;
1166 $wd->[1] = "$entry/.";
989 add $statgrp aio_stat "$path/$entry/.", sub { 1167 add $statgrp aio_stat $wd, sub {
990 if ($_[0] < 0) { 1168 if ($_[0] < 0) {
991 push @nondirs, $entry; 1169 push @nondirs, $entry;
992 } else { 1170 } else {
993 # need to check for real directory 1171 # need to check for real directory
994 aioreq_pri $pri; 1172 aioreq_pri $pri;
1173 $wd->[1] = $entry;
995 add $statgrp aio_lstat "$path/$entry", sub { 1174 add $statgrp aio_lstat $wd, sub {
996 if (-d _) { 1175 if (-d _) {
997 push @dirs, $entry; 1176 push @dirs, $entry;
998 1177
999 unless (--$ndirs) { 1178 unless (--$ndirs) {
1000 push @nondirs, @$entries; 1179 push @nondirs, @$entries;
1001 feed $statgrp; 1180 feed $statgrp;
1181 }
1182 } else {
1183 push @nondirs, $entry;
1002 } 1184 }
1003 } else {
1004 push @nondirs, $entry;
1005 } 1185 }
1006 } 1186 }
1007 } 1187 };
1008 }; 1188 };
1009 }; 1189 };
1010 }; 1190 };
1011 }; 1191 };
1012 }; 1192 };
1013 1193
1014 $grp 1194 $grp
1015} 1195}
1016 1196
1017=item aio_rmtree $path, $callback->($status) 1197=item aio_rmtree $pathname, $callback->($status)
1018 1198
1019Delete a directory tree starting (and including) C<$path>, return the 1199Delete a directory tree starting (and including) C<$path>, return the
1020status of the final C<rmdir> only. This is a composite request that 1200status of the final C<rmdir> only. This is a composite request that
1021uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1201uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1022everything else. 1202everything else.
1023 1203
1024=cut 1204=cut
1025 1205
1064callback with the fdatasync result code. 1244callback with the fdatasync result code.
1065 1245
1066If this call isn't available because your OS lacks it or it couldn't be 1246If this call isn't available because your OS lacks it or it couldn't be
1067detected, it will be emulated by calling C<fsync> instead. 1247detected, it will be emulated by calling C<fsync> instead.
1068 1248
1249=item aio_syncfs $fh, $callback->($status)
1250
1251Asynchronously call the syncfs syscall to sync the filesystem associated
1252to the given filehandle and call the callback with the syncfs result
1253code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1254errno to C<ENOSYS> nevertheless.
1255
1069=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1256=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1070 1257
1071Sync the data portion of the file specified by C<$offset> and C<$length> 1258Sync the data portion of the file specified by C<$offset> and C<$length>
1072to disk (but NOT the metadata), by calling the Linux-specific 1259to disk (but NOT the metadata), by calling the Linux-specific
1073sync_file_range call. If sync_file_range is not available or it returns 1260sync_file_range call. If sync_file_range is not available or it returns
1076C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, 1263C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1077C<IO::AIO::SYNC_FILE_RANGE_WRITE> and 1264C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1078C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range 1265C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1079manpage for details. 1266manpage for details.
1080 1267
1081=item aio_pathsync $path, $callback->($status) 1268=item aio_pathsync $pathname, $callback->($status)
1082 1269
1083This request tries to open, fsync and close the given path. This is a 1270This request tries to open, fsync and close the given path. This is a
1084composite request intended to sync directories after directory operations 1271composite request intended to sync directories after directory operations
1085(E.g. rename). This might not work on all operating systems or have any 1272(E.g. rename). This might not work on all operating systems or have any
1086specific effect, but usually it makes sure that directory changes get 1273specific effect, but usually it makes sure that directory changes get
1138 1325
1139This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1326This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1140scalars. 1327scalars.
1141 1328
1142It touches (reads or writes) all memory pages in the specified 1329It touches (reads or writes) all memory pages in the specified
1143range inside the scalar. All caveats and parameters are the same 1330range inside the scalar. All caveats and parameters are the same
1144as for C<aio_msync>, above, except for flags, which must be either 1331as for C<aio_msync>, above, except for flags, which must be either
1145C<0> (which reads all pages and ensures they are instantiated) or 1332C<0> (which reads all pages and ensures they are instantiated) or
1146C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and 1333C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1147writing an octet from it, which dirties the page). 1334writing an octet from it, which dirties the page).
1148 1335
1149=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1336=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1150 1337
1151This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1338This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1182documented under L<MISCELLANEOUS FUNCTIONS>. 1369documented under L<MISCELLANEOUS FUNCTIONS>.
1183 1370
1184Example: asynchronously lock all current and future pages into memory. 1371Example: asynchronously lock all current and future pages into memory.
1185 1372
1186 aio_mlockall IO::AIO::MCL_FUTURE; 1373 aio_mlockall IO::AIO::MCL_FUTURE;
1374
1375=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1376
1377Queries the extents of the given file (by calling the Linux C<FIEMAP>
1378ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
1379the ioctl is not available on your OS, then this request will fail with
1380C<ENOSYS>.
1381
1382C<$start> is the starting offset to query extents for, C<$length> is the
1383size of the range to query - if it is C<undef>, then the whole file will
1384be queried.
1385
1386C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
1387C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1388exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1389the data portion.
1390
1391C<$count> is the maximum number of extent records to return. If it is
1392C<undef>, then IO::AIO queries all extents of the range. As a very special
1393case, if it is C<0>, then the callback receives the number of extents
1394instead of the extents themselves (which is unreliable, see below).
1395
1396If an error occurs, the callback receives no arguments. The special
1397C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1398
1399Otherwise, the callback receives an array reference with extent
1400structures. Each extent structure is an array reference itself, with the
1401following members:
1402
1403 [$logical, $physical, $length, $flags]
1404
1405Flags is any combination of the following flag values (typically either C<0>
1406or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
1407
1408C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
1409C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
1410C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1411C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1412C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1413C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1414
1415At the time of this writing (Linux 3.2), this requets is unreliable unless
1416C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1417it to return all extents of a range for files with large number of
1418extents. The code works around all these issues if C<$count> is undef.
1187 1419
1188=item aio_group $callback->(...) 1420=item aio_group $callback->(...)
1189 1421
1190This is a very special aio request: Instead of doing something, it is a 1422This is a very special aio request: Instead of doing something, it is a
1191container for other aio requests, which is useful if you want to bundle 1423container for other aio requests, which is useful if you want to bundle
1228like sleep and file handle readable/writable, the overhead this creates is 1460like sleep and file handle readable/writable, the overhead this creates is
1229immense (it blocks a thread for a long time) so do not use this function 1461immense (it blocks a thread for a long time) so do not use this function
1230except to put your application under artificial I/O pressure. 1462except to put your application under artificial I/O pressure.
1231 1463
1232=back 1464=back
1465
1466
1467=head2 IO::AIO::WD - multiple working directories
1468
1469Your process only has one current working directory, which is used by all
1470threads. This makes it hard to use relative paths (some other component
1471could call C<chdir> at any time, and it is hard to control when the path
1472will be used by IO::AIO).
1473
1474One solution for this is to always use absolute paths. This usually works,
1475but can be quite slow (the kernel has to walk the whole path on every
1476access), and can also be a hassle to implement.
1477
1478Newer POSIX systems have a number of functions (openat, fdopendir,
1479futimensat and so on) that make it possible to specify working directories
1480per operation.
1481
1482For portability, and because the clowns who "designed", or shall I write,
1483perpetrated this new interface were obviously half-drunk, this abstraction
1484cannot be perfect, though.
1485
1486IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1487object. This object stores the canonicalised, absolute version of the
1488path, and on systems that allow it, also a directory file descriptor.
1489
1490Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1491or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1492object and a pathname instead (or the IO::AIO::WD object alone, which
1493gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1494IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1495to that IO::AIO::WD object.
1496
1497For example, to get a wd object for F</etc> and then stat F<passwd>
1498inside, you would write:
1499
1500 aio_wd "/etc", sub {
1501 my $etcdir = shift;
1502
1503 # although $etcdir can be undef on error, there is generally no reason
1504 # to check for errors here, as aio_stat will fail with ENOENT
1505 # when $etcdir is undef.
1506
1507 aio_stat [$etcdir, "passwd"], sub {
1508 # yay
1509 };
1510 };
1511
1512The fact that C<aio_wd> is a request and not a normal function shows that
1513creating an IO::AIO::WD object is itself a potentially blocking operation,
1514which is why it is done asynchronously.
1515
1516To stat the directory obtained with C<aio_wd> above, one could write
1517either of the following three request calls:
1518
1519 aio_lstat "/etc" , sub { ... # pathname as normal string
1520 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1521 aio_lstat $wd , sub { ... # shorthand for the previous
1522
1523As with normal pathnames, IO::AIO keeps a copy of the working directory
1524object and the pathname string, so you could write the following without
1525causing any issues due to C<$path> getting reused:
1526
1527 my $path = [$wd, undef];
1528
1529 for my $name (qw(abc def ghi)) {
1530 $path->[1] = $name;
1531 aio_stat $path, sub {
1532 # ...
1533 };
1534 }
1535
1536There are some caveats: when directories get renamed (or deleted), the
1537pathname string doesn't change, so will point to the new directory (or
1538nowhere at all), while the directory fd, if available on the system,
1539will still point to the original directory. Most functions accepting a
1540pathname will use the directory fd on newer systems, and the string on
1541older systems. Some functions (such as realpath) will always rely on the
1542string form of the pathname.
1543
1544So this functionality is mainly useful to get some protection against
1545C<chdir>, to easily get an absolute path out of a relative path for future
1546reference, and to speed up doing many operations in the same directory
1547(e.g. when stat'ing all files in a directory).
1548
1549The following functions implement this working directory abstraction:
1550
1551=over 4
1552
1553=item aio_wd $pathname, $callback->($wd)
1554
1555Asynchonously canonicalise the given pathname and convert it to an
1556IO::AIO::WD object representing it. If possible and supported on the
1557system, also open a directory fd to speed up pathname resolution relative
1558to this working directory.
1559
1560If something goes wrong, then C<undef> is passwd to the callback instead
1561of a working directory object and C<$!> is set appropriately. Since
1562passing C<undef> as working directory component of a pathname fails the
1563request with C<ENOENT>, there is often no need for error checking in the
1564C<aio_wd> callback, as future requests using the value will fail in the
1565expected way.
1566
1567=item IO::AIO::CWD
1568
1569This is a compiletime constant (object) that represents the process
1570current working directory.
1571
1572Specifying this object as working directory object for a pathname is as if
1573the pathname would be specified directly, without a directory object. For
1574example, these calls are functionally identical:
1575
1576 aio_stat "somefile", sub { ... };
1577 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1578
1579=back
1580
1581To recover the path associated with an IO::AIO::WD object, you can use
1582C<aio_realpath>:
1583
1584 aio_realpath $wd, sub {
1585 warn "path is $_[0]\n";
1586 };
1587
1588Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
1589sometimes, fall back to using an absolue path.
1233 1590
1234=head2 IO::AIO::REQ CLASS 1591=head2 IO::AIO::REQ CLASS
1235 1592
1236All non-aggregate C<aio_*> functions return an object of this class when 1593All non-aggregate C<aio_*> functions return an object of this class when
1237called in non-void context. 1594called in non-void context.
1355 1712
1356Sets a feeder/generator on this group: every group can have an attached 1713Sets a feeder/generator on this group: every group can have an attached
1357generator that generates requests if idle. The idea behind this is that, 1714generator that generates requests if idle. The idea behind this is that,
1358although you could just queue as many requests as you want in a group, 1715although you could just queue as many requests as you want in a group,
1359this might starve other requests for a potentially long time. For example, 1716this might starve other requests for a potentially long time. For example,
1360C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, 1717C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1361delaying any later requests for a long time. 1718requests, delaying any later requests for a long time.
1362 1719
1363To avoid this, and allow incremental generation of requests, you can 1720To avoid this, and allow incremental generation of requests, you can
1364instead a group and set a feeder on it that generates those requests. The 1721instead a group and set a feeder on it that generates those requests. The
1365feed callback will be called whenever there are few enough (see C<limit>, 1722feed callback will be called whenever there are few enough (see C<limit>,
1366below) requests active in the group itself and is expected to queue more 1723below) requests active in the group itself and is expected to queue more
1415 1772
1416See C<poll_cb> for an example. 1773See C<poll_cb> for an example.
1417 1774
1418=item IO::AIO::poll_cb 1775=item IO::AIO::poll_cb
1419 1776
1420Process some outstanding events on the result pipe. You have to call 1777Process some requests that have reached the result phase (i.e. they have
1778been executed but the results are not yet reported). You have to call
1779this "regularly" to finish outstanding requests.
1780
1421this regularly. Returns C<0> if all events could be processed (or there 1781Returns C<0> if all events could be processed (or there were no
1422were no events to process), or C<-1> if it returned earlier for whatever 1782events to process), or C<-1> if it returned earlier for whatever
1423reason. Returns immediately when no events are outstanding. The amount of 1783reason. Returns immediately when no events are outstanding. The amount
1424events processed depends on the settings of C<IO::AIO::max_poll_req> and 1784of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1425C<IO::AIO::max_poll_time>. 1785C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1426 1786
1427If not all requests were processed for whatever reason, the filehandle 1787If not all requests were processed for whatever reason, the poll file
1428will still be ready when C<poll_cb> returns, so normally you don't have to 1788descriptor will still be ready when C<poll_cb> returns, so normally you
1429do anything special to have it called later. 1789don't have to do anything special to have it called later.
1430 1790
1431Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes 1791Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1432ready, it can be beneficial to call this function from loops which submit 1792ready, it can be beneficial to call this function from loops which submit
1433a lot of requests, to make sure the results get processed when they become 1793a lot of requests, to make sure the results get processed when they become
1434available and not just when the loop is finished and the event loop takes 1794available and not just when the loop is finished and the event loop takes
1443 poll => 'r', async => 1, 1803 poll => 'r', async => 1,
1444 cb => \&IO::AIO::poll_cb); 1804 cb => \&IO::AIO::poll_cb);
1445 1805
1446=item IO::AIO::poll_wait 1806=item IO::AIO::poll_wait
1447 1807
1448If there are any outstanding requests and none of them in the result 1808Wait until either at least one request is in the result phase or no
1449phase, wait till the result filehandle becomes ready for reading (simply 1809requests are outstanding anymore.
1450does a C<select> on the filehandle. This is useful if you want to 1810
1451synchronously wait for some requests to finish). 1811This is useful if you want to synchronously wait for some requests to
1812become ready, without actually handling them.
1452 1813
1453See C<nreqs> for an example. 1814See C<nreqs> for an example.
1454 1815
1455=item IO::AIO::poll 1816=item IO::AIO::poll
1456 1817
1577 1938
1578This is a very bad function to use in interactive programs because it 1939This is a very bad function to use in interactive programs because it
1579blocks, and a bad way to reduce concurrency because it is inexact: Better 1940blocks, and a bad way to reduce concurrency because it is inexact: Better
1580use an C<aio_group> together with a feed callback. 1941use an C<aio_group> together with a feed callback.
1581 1942
1582It's main use is in scripts without an event loop - when you want to stat 1943Its main use is in scripts without an event loop - when you want to stat
1583a lot of files, you can write somehting like this: 1944a lot of files, you can write somehting like this:
1584 1945
1585 IO::AIO::max_outstanding 32; 1946 IO::AIO::max_outstanding 32;
1586 1947
1587 for my $path (...) { 1948 for my $path (...) {
1627 1988
1628=back 1989=back
1629 1990
1630=head3 MISCELLANEOUS FUNCTIONS 1991=head3 MISCELLANEOUS FUNCTIONS
1631 1992
1632IO::AIO implements some functions that might be useful, but are not 1993IO::AIO implements some functions that are useful when you want to use
1633asynchronous. 1994some "Advanced I/O" function not available to in Perl, without going the
1995"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
1996counterpart.
1634 1997
1635=over 4 1998=over 4
1636 1999
1637=item IO::AIO::sendfile $ofh, $ifh, $offset, $count 2000=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1638 2001
1645 2008
1646=item IO::AIO::fadvise $fh, $offset, $len, $advice 2009=item IO::AIO::fadvise $fh, $offset, $len, $advice
1647 2010
1648Simply calls the C<posix_fadvise> function (see its 2011Simply calls the C<posix_fadvise> function (see its
1649manpage for details). The following advice constants are 2012manpage for details). The following advice constants are
1650avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>, 2013available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1651C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>, 2014C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1652C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>. 2015C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1653 2016
1654On systems that do not implement C<posix_fadvise>, this function returns 2017On systems that do not implement C<posix_fadvise>, this function returns
1655ENOSYS, otherwise the return value of C<posix_fadvise>. 2018ENOSYS, otherwise the return value of C<posix_fadvise>.
1656 2019
1657=item IO::AIO::madvise $scalar, $offset, $len, $advice 2020=item IO::AIO::madvise $scalar, $offset, $len, $advice
1658 2021
1659Simply calls the C<posix_madvise> function (see its 2022Simply calls the C<posix_madvise> function (see its
1660manpage for details). The following advice constants are 2023manpage for details). The following advice constants are
1661avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, 2024available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1662C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>. 2025C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1663 2026
1664On systems that do not implement C<posix_madvise>, this function returns 2027On systems that do not implement C<posix_madvise>, this function returns
1665ENOSYS, otherwise the return value of C<posix_madvise>. 2028ENOSYS, otherwise the return value of C<posix_madvise>.
1666 2029
1667=item IO::AIO::mprotect $scalar, $offset, $len, $protect 2030=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1668 2031
1669Simply calls the C<mprotect> function on the preferably AIO::mmap'ed 2032Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1670$scalar (see its manpage for details). The following protect 2033$scalar (see its manpage for details). The following protect
1671constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, 2034constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1672C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. 2035C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1673 2036
1674On systems that do not implement C<mprotect>, this function returns 2037On systems that do not implement C<mprotect>, this function returns
1675ENOSYS, otherwise the return value of C<mprotect>. 2038ENOSYS, otherwise the return value of C<mprotect>.
1676 2039
1677=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 2040=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1678 2041
1679Memory-maps a file (or anonymous memory range) and attaches it to the 2042Memory-maps a file (or anonymous memory range) and attaches it to the
1680given C<$scalar>, which will act like a string scalar. 2043given C<$scalar>, which will act like a string scalar. Returns true on
2044success, and false otherwise.
1681 2045
1682The only operations allowed on the scalar are C<substr>/C<vec> that don't 2046The only operations allowed on the scalar are C<substr>/C<vec> that don't
1683change the string length, and most read-only operations such as copying it 2047change the string length, and most read-only operations such as copying it
1684or searching it with regexes and so on. 2048or searching it with regexes and so on.
1685 2049
1696filesize. 2060filesize.
1697 2061
1698C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, 2062C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1699C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, 2063C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1700 2064
1701C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or 2065C<$flags> can be a combination of
1702C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when 2066C<IO::AIO::MAP_SHARED> or
1703not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS> 2067C<IO::AIO::MAP_PRIVATE>,
2068or a number of system-specific flags (when not available, the are C<0>):
1704(which is set to C<MAP_ANON> if your system only provides this 2069C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1705constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>, 2070C<IO::AIO::MAP_LOCKED>,
1706C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or 2071C<IO::AIO::MAP_NORESERVE>,
2072C<IO::AIO::MAP_POPULATE>,
1707C<IO::AIO::MAP_NONBLOCK> 2073C<IO::AIO::MAP_NONBLOCK>,
2074C<IO::AIO::MAP_FIXED>,
2075C<IO::AIO::MAP_GROWSDOWN>,
2076C<IO::AIO::MAP_32BIT>,
2077C<IO::AIO::MAP_HUGETLB> or
2078C<IO::AIO::MAP_STACK>.
1708 2079
1709If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. 2080If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1710 2081
1711C<$offset> is the offset from the start of the file - it generally must be 2082C<$offset> is the offset from the start of the file - it generally must be
1712a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. 2083a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1737 2108
1738Calls the C<munlockall> function. 2109Calls the C<munlockall> function.
1739 2110
1740On systems that do not implement C<munlockall>, this function returns 2111On systems that do not implement C<munlockall>, this function returns
1741ENOSYS, otherwise the return value of C<munlockall>. 2112ENOSYS, otherwise the return value of C<munlockall>.
2113
2114=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
2115
2116Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
2117C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
2118should be the file offset.
2119
2120C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
2121silently corrupt the data in this case.
2122
2123The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
2124C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
2125C<IO::AIO::SPLICE_F_GIFT>.
2126
2127See the C<splice(2)> manpage for details.
2128
2129=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
2130
2131Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
2132description for C<IO::AIO::splice> above for details.
2133
2134=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
2135
2136Attempts to query or change the pipe buffer size. Obviously works only
2137on pipes, and currently works only on GNU/Linux systems, and fails with
2138C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
2139size on other systems, drop me a note.
2140
2141=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
2142
2143This is a direct interface to the Linux L<pipe2(2)> system call. If
2144C<$flags> is missing or C<0>, then this should be the same as a call to
2145perl's built-in C<pipe> function and create a new pipe, and works on
2146systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
2147(..., 4096, O_BINARY)>.
2148
2149If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
2150the given flags (Linux 2.6.27, glibc 2.9).
2151
2152On success, the read and write file handles are returned.
2153
2154On error, nothing will be returned. If the pipe2 syscall is missing and
2155C<$flags> is non-zero, fails with C<ENOSYS>.
2156
2157Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
2158time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
2159C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1742 2160
1743=back 2161=back
1744 2162
1745=cut 2163=cut
1746 2164
1781 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 2199 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1782 \&IO::AIO::poll_cb); 2200 \&IO::AIO::poll_cb);
1783 2201
1784=head2 FORK BEHAVIOUR 2202=head2 FORK BEHAVIOUR
1785 2203
1786This module should do "the right thing" when the process using it forks: 2204Usage of pthreads in a program changes the semantics of fork
2205considerably. Specifically, only async-safe functions can be called after
2206fork. Perl doesn't know about this, so in general, you cannot call fork
2207with defined behaviour in perl if pthreads are involved. IO::AIO uses
2208pthreads, so this applies, but many other extensions and (for inexplicable
2209reasons) perl itself often is linked against pthreads, so this limitation
2210applies to quite a lot of perls.
1787 2211
1788Before the fork, IO::AIO enters a quiescent state where no requests 2212This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1789can be added in other threads and no results will be processed. After 2213only works in the process that loaded it. Forking is fully supported, but
1790the fork the parent simply leaves the quiescent state and continues 2214using IO::AIO in the child is not.
1791request/result processing, while the child frees the request/result queue
1792(so that the requests started before the fork will only be handled in the
1793parent). Threads will be started on demand until the limit set in the
1794parent process has been reached again.
1795 2215
1796In short: the parent will, after a short pause, continue as if fork had 2216You might get around by not I<using> IO::AIO before (or after)
1797not been called, while the child will act as if IO::AIO has not been used 2217forking. You could also try to call the L<IO::AIO::reinit> function in the
1798yet. 2218child:
2219
2220=over 4
2221
2222=item IO::AIO::reinit
2223
2224Abandons all current requests and I/O threads and simply reinitialises all
2225data structures. This is not an operation supported by any standards, but
2226happens to work on GNU/Linux and some newer BSD systems.
2227
2228The only reasonable use for this function is to call it after forking, if
2229C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
2230the process will result in undefined behaviour. Calling it at any time
2231will also result in any undefined (by POSIX) behaviour.
2232
2233=back
1799 2234
1800=head2 MEMORY USAGE 2235=head2 MEMORY USAGE
1801 2236
1802Per-request usage: 2237Per-request usage:
1803 2238

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