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Revision 1.175 by root, Sun Jan 10 20:37:33 2010 UTC vs.
Revision 1.209 by root, Tue Sep 27 00:41:51 2011 UTC

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4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
9 aio_open "/etc/passwd", O_RDONLY, 0, sub { 9 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10 my $fh = shift 10 my $fh = shift
11 or die "/etc/passwd: $!"; 11 or die "/etc/passwd: $!";
12 ... 12 ...
13 }; 13 };
14 14
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76 76
77 # register the IO::AIO callback with EV 77 # register the IO::AIO callback with EV
78 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;
79 79
80 # queue the request to open /etc/passwd 80 # queue the request to open /etc/passwd
81 aio_open "/etc/passwd", O_RDONLY, 0, sub { 81 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
82 my $fh = shift 82 my $fh = shift
83 or die "error while opening: $!"; 83 or die "error while opening: $!";
84 84
85 # stat'ing filehandles is generally non-blocking 85 # stat'ing filehandles is generally non-blocking
86 my $size = -s $fh; 86 my $size = -s $fh;
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168use common::sense; 168use common::sense;
169 169
170use base 'Exporter'; 170use base 'Exporter';
171 171
172BEGIN { 172BEGIN {
173 our $VERSION = '3.5'; 173 our $VERSION = '4.0';
174 174
175 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 175 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
176 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
177 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync 177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
178 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
179 aio_rename aio_link aio_move aio_copy aio_group 180 aio_rename aio_link aio_move aio_copy aio_group
180 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
181 aio_chmod aio_utime aio_truncate 182 aio_chmod aio_utime aio_truncate
182 aio_msync aio_mtouch aio_statvfs); 183 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs
185 aio_wd);
183 186
184 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
185 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
186 min_parallel max_parallel max_idle 189 min_parallel max_parallel max_idle idle_timeout
187 nreqs nready npending nthreads 190 nreqs nready npending nthreads
188 max_poll_time max_poll_reqs 191 max_poll_time max_poll_reqs
189 sendfile fadvise); 192 sendfile fadvise madvise
193 mmap munmap munlock munlockall);
190 194
191 push @AIO_REQ, qw(aio_busy); # not exported 195 push @AIO_REQ, qw(aio_busy); # not exported
192 196
193 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 197 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
194 198
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202 206
203This section simply lists the prototypes of the most important functions 207This section simply lists the prototypes of the most important functions
204for quick reference. See the following sections for function-by-function 208for quick reference. See the following sections for function-by-function
205documentation. 209documentation.
206 210
211 aio_wd $pathname, $callback->($wd)
207 aio_open $pathname, $flags, $mode, $callback->($fh) 212 aio_open $pathname, $flags, $mode, $callback->($fh)
208 aio_close $fh, $callback->($status) 213 aio_close $fh, $callback->($status)
209 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 214 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
210 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 215 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
211 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 216 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
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216 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 221 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
217 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 222 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
218 aio_truncate $fh_or_path, $offset, $callback->($status) 223 aio_truncate $fh_or_path, $offset, $callback->($status)
219 aio_chmod $fh_or_path, $mode, $callback->($status) 224 aio_chmod $fh_or_path, $mode, $callback->($status)
220 aio_unlink $pathname, $callback->($status) 225 aio_unlink $pathname, $callback->($status)
221 aio_mknod $path, $mode, $dev, $callback->($status) 226 aio_mknod $pathname, $mode, $dev, $callback->($status)
222 aio_link $srcpath, $dstpath, $callback->($status) 227 aio_link $srcpath, $dstpath, $callback->($status)
223 aio_symlink $srcpath, $dstpath, $callback->($status) 228 aio_symlink $srcpath, $dstpath, $callback->($status)
224 aio_readlink $path, $callback->($link) 229 aio_readlink $pathname, $callback->($link)
230 aio_realpath $pathname, $callback->($link)
225 aio_rename $srcpath, $dstpath, $callback->($status) 231 aio_rename $srcpath, $dstpath, $callback->($status)
226 aio_mkdir $pathname, $mode, $callback->($status) 232 aio_mkdir $pathname, $mode, $callback->($status)
227 aio_rmdir $pathname, $callback->($status) 233 aio_rmdir $pathname, $callback->($status)
228 aio_readdir $pathname, $callback->($entries) 234 aio_readdir $pathname, $callback->($entries)
229 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 235 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
230 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 236 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
231 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 237 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
232 aio_load $path, $data, $callback->($status) 238 aio_load $pathname, $data, $callback->($status)
233 aio_copy $srcpath, $dstpath, $callback->($status) 239 aio_copy $srcpath, $dstpath, $callback->($status)
234 aio_move $srcpath, $dstpath, $callback->($status) 240 aio_move $srcpath, $dstpath, $callback->($status)
235 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 241 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
236 aio_rmtree $path, $callback->($status) 242 aio_rmtree $pathname, $callback->($status)
237 aio_sync $callback->($status) 243 aio_sync $callback->($status)
244 aio_syncfs $fh, $callback->($status)
238 aio_fsync $fh, $callback->($status) 245 aio_fsync $fh, $callback->($status)
239 aio_fdatasync $fh, $callback->($status) 246 aio_fdatasync $fh, $callback->($status)
240 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 247 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
241 aio_pathsync $path, $callback->($status) 248 aio_pathsync $pathname, $callback->($status)
242 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 249 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
243 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 250 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252 aio_mlockall $flags, $callback->($status)
244 aio_group $callback->(...) 253 aio_group $callback->(...)
245 aio_nop $callback->() 254 aio_nop $callback->()
246 255
247 $prev_pri = aioreq_pri [$pri] 256 $prev_pri = aioreq_pri [$pri]
248 aioreq_nice $pri_adjust 257 aioreq_nice $pri_adjust
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254 IO::AIO::max_poll_reqs $nreqs 263 IO::AIO::max_poll_reqs $nreqs
255 IO::AIO::max_poll_time $seconds 264 IO::AIO::max_poll_time $seconds
256 IO::AIO::min_parallel $nthreads 265 IO::AIO::min_parallel $nthreads
257 IO::AIO::max_parallel $nthreads 266 IO::AIO::max_parallel $nthreads
258 IO::AIO::max_idle $nthreads 267 IO::AIO::max_idle $nthreads
268 IO::AIO::idle_timeout $seconds
259 IO::AIO::max_outstanding $maxreqs 269 IO::AIO::max_outstanding $maxreqs
260 IO::AIO::nreqs 270 IO::AIO::nreqs
261 IO::AIO::nready 271 IO::AIO::nready
262 IO::AIO::npending 272 IO::AIO::npending
263 273
264 IO::AIO::sendfile $ofh, $ifh, $offset, $count 274 IO::AIO::sendfile $ofh, $ifh, $offset, $count
265 IO::AIO::fadvise $fh, $offset, $len, $advice 275 IO::AIO::fadvise $fh, $offset, $len, $advice
266 IO::AIO::mlockall $flags 276 IO::AIO::madvise $scalar, $offset, $length, $advice
277 IO::AIO::mprotect $scalar, $offset, $length, $protect
278 IO::AIO::munlock $scalar, $offset = 0, $length = undef
267 IO::AIO::munlockall 279 IO::AIO::munlockall
268 280
269=head2 AIO REQUEST FUNCTIONS 281=head2 AIO REQUEST FUNCTIONS
270 282
271All the C<aio_*> calls are more or less thin wrappers around the syscall 283All the C<aio_*> calls are more or less thin wrappers around the syscall
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280internally until the request has finished. 292internally until the request has finished.
281 293
282All functions return request objects of type L<IO::AIO::REQ> that allow 294All functions return request objects of type L<IO::AIO::REQ> that allow
283further manipulation of those requests while they are in-flight. 295further manipulation of those requests while they are in-flight.
284 296
285The pathnames you pass to these routines I<must> be absolute and 297The pathnames you pass to these routines I<should> be absolute. The
286encoded as octets. The reason for the former is that at the time the 298reason for this is that at the time the request is being executed, the
287request is being executed, the current working directory could have 299current working directory could have changed. Alternatively, you can make
288changed. Alternatively, you can make sure that you never change the 300sure that you never change the current working directory anywhere in
289current working directory anywhere in the program and then use relative 301the program and then use relative paths. Lastly, you can take advantage
290paths. 302of IO::AIOs working directory abstraction - see the description of the
303C<IO::AIO::WD> class later in this document.
291 304
292To encode pathnames as octets, either make sure you either: a) always pass 305To encode pathnames as octets, either make sure you either: a) always pass
293in filenames you got from outside (command line, readdir etc.) without 306in filenames you got from outside (command line, readdir etc.) without
294tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 307tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
295your pathnames to the locale (or other) encoding in effect in the user 308your pathnames to the locale (or other) encoding in effect in the user
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352by the umask in effect then the request is being executed, so better never 365by the umask in effect then the request is being executed, so better never
353change the umask. 366change the umask.
354 367
355Example: 368Example:
356 369
357 aio_open "/etc/passwd", O_RDONLY, 0, sub { 370 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
358 if ($_[0]) { 371 if ($_[0]) {
359 print "open successful, fh is $_[0]\n"; 372 print "open successful, fh is $_[0]\n";
360 ... 373 ...
361 } else { 374 } else {
362 die "open failed: $!\n"; 375 die "open failed: $!\n";
363 } 376 }
364 }; 377 };
365 378
379In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
380C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
381following POSIX and non-POSIX constants are available (missing ones on
382your system are, as usual, C<0>):
383
384C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
385C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
386C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
387
366 388
367=item aio_close $fh, $callback->($status) 389=item aio_close $fh, $callback->($status)
368 390
369Asynchronously close a file and call the callback with the result 391Asynchronously close a file and call the callback with the result
370code. 392code.
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420 442
421Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 443Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
422reading at byte offset C<$in_offset>, and starts writing at the current 444reading at byte offset C<$in_offset>, and starts writing at the current
423file offset of C<$out_fh>. Because of that, it is not safe to issue more 445file offset of C<$out_fh>. Because of that, it is not safe to issue more
424than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 446than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
425other. 447other. The same C<$in_fh> works fine though, as this function does not
448move or use the file offset of C<$in_fh>.
426 449
450Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
451are written, and there is no way to find out how many more bytes have been
452read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
453number of bytes written to C<$out_fh>. Only if the result value equals
454C<$length> one can assume that C<$length> bytes have been read.
455
456Unlike with other C<aio_> functions, it makes a lot of sense to use
457C<aio_sendfile> on non-blocking sockets, as long as one end (typically
458the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
459the socket I/O will be non-blocking. Note, however, that you can run
460into a trap where C<aio_sendfile> reads some data with readahead, then
461fails to write all data, and when the socket is ready the next time, the
462data in the cache is already lost, forcing C<aio_sendfile> to again hit
463the disk. Explicit C<aio_read> + C<aio_write> let's you better control
464resource usage.
465
427This call tries to make use of a native C<sendfile> syscall to provide 466This call tries to make use of a native C<sendfile>-like syscall to
428zero-copy operation. For this to work, C<$out_fh> should refer to a 467provide zero-copy operation. For this to work, C<$out_fh> should refer to
429socket, and C<$in_fh> should refer to mmap'able file. 468a socket, and C<$in_fh> should refer to an mmap'able file.
430 469
431If a native sendfile cannot be found or it fails with C<ENOSYS>, 470If a native sendfile cannot be found or it fails with C<ENOSYS>,
432C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>, 471C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
433it will be emulated, so you can call C<aio_sendfile> on any type of 472C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
434filehandle regardless of the limitations of the operating system. 473type of filehandle regardless of the limitations of the operating system.
435 474
436Please note, however, that C<aio_sendfile> can read more bytes from 475As native sendfile syscalls (as practically any non-POSIX interface hacked
437C<$in_fh> than are written, and there is no way to find out how many 476together in a hurry to improve benchmark numbers) tend to be rather buggy
438bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 477on many systems, this implementation tries to work around some known bugs
439provides the number of bytes written to C<$out_fh>. Only if the result 478in Linux and FreeBSD kernels (probably others, too), but that might fail,
440value equals C<$length> one can assume that C<$length> bytes have been 479so you really really should check the return value of C<aio_sendfile> -
441read. 480fewre bytes than expected might have been transferred.
442 481
443 482
444=item aio_readahead $fh,$offset,$length, $callback->($retval) 483=item aio_readahead $fh,$offset,$length, $callback->($retval)
445 484
446C<aio_readahead> populates the page cache with data from a file so that 485C<aio_readahead> populates the page cache with data from a file so that
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468for an explanation. 507for an explanation.
469 508
470Currently, the stats are always 64-bit-stats, i.e. instead of returning an 509Currently, the stats are always 64-bit-stats, i.e. instead of returning an
471error when stat'ing a large file, the results will be silently truncated 510error when stat'ing a large file, the results will be silently truncated
472unless perl itself is compiled with large file support. 511unless perl itself is compiled with large file support.
512
513To help interpret the mode and dev/rdev stat values, IO::AIO offers the
514following constants and functions (if not implemented, the constants will
515be C<0> and the functions will either C<croak> or fall back on traditional
516behaviour).
517
518C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
519C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
520C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
473 521
474Example: Print the length of F</etc/passwd>: 522Example: Print the length of F</etc/passwd>:
475 523
476 aio_stat "/etc/passwd", sub { 524 aio_stat "/etc/passwd", sub {
477 $_[0] and die "stat failed: $!"; 525 $_[0] and die "stat failed: $!";
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569 617
570Asynchronously unlink (delete) a file and call the callback with the 618Asynchronously unlink (delete) a file and call the callback with the
571result code. 619result code.
572 620
573 621
574=item aio_mknod $path, $mode, $dev, $callback->($status) 622=item aio_mknod $pathname, $mode, $dev, $callback->($status)
575 623
576[EXPERIMENTAL] 624[EXPERIMENTAL]
577 625
578Asynchronously create a device node (or fifo). See mknod(2). 626Asynchronously create a device node (or fifo). See mknod(2).
579 627
580The only (POSIX-) portable way of calling this function is: 628The only (POSIX-) portable way of calling this function is:
581 629
582 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 630 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
583 631
632See C<aio_stat> for info about some potentially helpful extra constants
633and functions.
584 634
585=item aio_link $srcpath, $dstpath, $callback->($status) 635=item aio_link $srcpath, $dstpath, $callback->($status)
586 636
587Asynchronously create a new link to the existing object at C<$srcpath> at 637Asynchronously create a new link to the existing object at C<$srcpath> at
588the path C<$dstpath> and call the callback with the result code. 638the path C<$dstpath> and call the callback with the result code.
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592 642
593Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 643Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
594the path C<$dstpath> and call the callback with the result code. 644the path C<$dstpath> and call the callback with the result code.
595 645
596 646
597=item aio_readlink $path, $callback->($link) 647=item aio_readlink $pathname, $callback->($link)
598 648
599Asynchronously read the symlink specified by C<$path> and pass it to 649Asynchronously read the symlink specified by C<$path> and pass it to
600the callback. If an error occurs, nothing or undef gets passed to the 650the callback. If an error occurs, nothing or undef gets passed to the
601callback. 651callback.
602 652
603 653
654=item aio_realpath $pathname, $callback->($path)
655
656Asynchronously make the path absolute and resolve any symlinks in
657C<$path>. The resulting path only consists of directories (Same as
658L<Cwd::realpath>).
659
660This request can be used to get the absolute path of the current working
661directory by passing it a path of F<.> (a single dot).
662
663
604=item aio_rename $srcpath, $dstpath, $callback->($status) 664=item aio_rename $srcpath, $dstpath, $callback->($status)
605 665
606Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 666Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
607rename(2) and call the callback with the result code. 667rename(2) and call the callback with the result code.
608 668
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630array-ref with the filenames. 690array-ref with the filenames.
631 691
632 692
633=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) 693=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
634 694
635Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune 695Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
636behaviour and output format. In case of an error, C<$entries> will be 696tune behaviour and output format. In case of an error, C<$entries> will be
637C<undef>. 697C<undef>.
638 698
639The flags are a combination of the following constants, ORed together (the 699The flags are a combination of the following constants, ORed together (the
640flags will also be passed to the callback, possibly modified): 700flags will also be passed to the callback, possibly modified):
641 701
642=over 4 702=over 4
643 703
644=item IO::AIO::READDIR_DENTS 704=item IO::AIO::READDIR_DENTS
645 705
646When this flag is off, then the callback gets an arrayref with of names 706When this flag is off, then the callback gets an arrayref consisting of
647only (as with C<aio_readdir>), otherwise it gets an arrayref with 707names only (as with C<aio_readdir>), otherwise it gets an arrayref with
648C<[$name, $type, $inode]> arrayrefs, each describing a single directory 708C<[$name, $type, $inode]> arrayrefs, each describing a single directory
649entry in more detail. 709entry in more detail.
650 710
651C<$name> is the name of the entry. 711C<$name> is the name of the entry.
652 712
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665systems that do not deliver the inode information. 725systems that do not deliver the inode information.
666 726
667=item IO::AIO::READDIR_DIRS_FIRST 727=item IO::AIO::READDIR_DIRS_FIRST
668 728
669When this flag is set, then the names will be returned in an order where 729When this flag is set, then the names will be returned in an order where
670likely directories come first. This is useful when you need to quickly 730likely directories come first, in optimal stat order. This is useful when
671find directories, or you want to find all directories while avoiding to 731you need to quickly find directories, or you want to find all directories
672stat() each entry. 732while avoiding to stat() each entry.
673 733
674If the system returns type information in readdir, then this is used 734If the system returns type information in readdir, then this is used
675to find directories directly. Otherwise, likely directories are files 735to find directories directly. Otherwise, likely directories are names
676beginning with ".", or otherwise files with no dots, of which files with 736beginning with ".", or otherwise names with no dots, of which names with
677short names are tried first. 737short names are tried first.
678 738
679=item IO::AIO::READDIR_STAT_ORDER 739=item IO::AIO::READDIR_STAT_ORDER
680 740
681When this flag is set, then the names will be returned in an order 741When this flag is set, then the names will be returned in an order
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688 748
689=item IO::AIO::READDIR_FOUND_UNKNOWN 749=item IO::AIO::READDIR_FOUND_UNKNOWN
690 750
691This flag should not be set when calling C<aio_readdirx>. Instead, it 751This flag should not be set when calling C<aio_readdirx>. Instead, it
692is being set by C<aio_readdirx>, when any of the C<$type>'s found were 752is being set by C<aio_readdirx>, when any of the C<$type>'s found were
693C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all 753C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
694C<$type>'s are known, which can be used to speed up some algorithms. 754C<$type>'s are known, which can be used to speed up some algorithms.
695 755
696=back 756=back
697 757
698 758
699=item aio_load $path, $data, $callback->($status) 759=item aio_load $pathname, $data, $callback->($status)
700 760
701This is a composite request that tries to fully load the given file into 761This is a composite request that tries to fully load the given file into
702memory. Status is the same as with aio_read. 762memory. Status is the same as with aio_read.
703 763
704=cut 764=cut
… …
826 if ($_[0] && $! == EXDEV) { 886 if ($_[0] && $! == EXDEV) {
827 aioreq_pri $pri; 887 aioreq_pri $pri;
828 add $grp aio_copy $src, $dst, sub { 888 add $grp aio_copy $src, $dst, sub {
829 $grp->result ($_[0]); 889 $grp->result ($_[0]);
830 890
831 if (!$_[0]) { 891 unless ($_[0]) {
832 aioreq_pri $pri; 892 aioreq_pri $pri;
833 add $grp aio_unlink $src; 893 add $grp aio_unlink $src;
834 } 894 }
835 }; 895 };
836 } else { 896 } else {
… …
839 }; 899 };
840 900
841 $grp 901 $grp
842} 902}
843 903
844=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 904=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
845 905
846Scans a directory (similar to C<aio_readdir>) but additionally tries to 906Scans a directory (similar to C<aio_readdir>) but additionally tries to
847efficiently separate the entries of directory C<$path> into two sets of 907efficiently separate the entries of directory C<$path> into two sets of
848names, directories you can recurse into (directories), and ones you cannot 908names, directories you can recurse into (directories), and ones you cannot
849recurse into (everything else, including symlinks to directories). 909recurse into (everything else, including symlinks to directories).
… …
880Then entries will be sorted into likely directories a non-initial dot 940Then entries will be sorted into likely directories a non-initial dot
881currently) and likely non-directories (see C<aio_readdirx>). Then every 941currently) and likely non-directories (see C<aio_readdirx>). Then every
882entry plus an appended C</.> will be C<stat>'ed, likely directories first, 942entry plus an appended C</.> will be C<stat>'ed, likely directories first,
883in order of their inode numbers. If that succeeds, it assumes that the 943in order of their inode numbers. If that succeeds, it assumes that the
884entry is a directory or a symlink to directory (which will be checked 944entry is a directory or a symlink to directory (which will be checked
885seperately). This is often faster than stat'ing the entry itself because 945separately). This is often faster than stat'ing the entry itself because
886filesystems might detect the type of the entry without reading the inode 946filesystems might detect the type of the entry without reading the inode
887data (e.g. ext2fs filetype feature), even on systems that cannot return 947data (e.g. ext2fs filetype feature), even on systems that cannot return
888the filetype information on readdir. 948the filetype information on readdir.
889 949
890If the known number of directories (link count - 2) has been reached, the 950If the known number of directories (link count - 2) has been reached, the
… …
976 }; 1036 };
977 1037
978 $grp 1038 $grp
979} 1039}
980 1040
981=item aio_rmtree $path, $callback->($status) 1041=item aio_rmtree $pathname, $callback->($status)
982 1042
983Delete a directory tree starting (and including) C<$path>, return the 1043Delete a directory tree starting (and including) C<$path>, return the
984status of the final C<rmdir> only. This is a composite request that 1044status of the final C<rmdir> only. This is a composite request that
985uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1045uses C<aio_scandir> to recurse into and rmdir directories, and unlink
986everything else. 1046everything else.
… …
1028callback with the fdatasync result code. 1088callback with the fdatasync result code.
1029 1089
1030If this call isn't available because your OS lacks it or it couldn't be 1090If this call isn't available because your OS lacks it or it couldn't be
1031detected, it will be emulated by calling C<fsync> instead. 1091detected, it will be emulated by calling C<fsync> instead.
1032 1092
1093=item aio_syncfs $fh, $callback->($status)
1094
1095Asynchronously call the syncfs syscall to sync the filesystem associated
1096to the given filehandle and call the callback with the syncfs result
1097code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1098errno to C<ENOSYS> nevertheless.
1099
1033=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1100=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1034 1101
1035Sync the data portion of the file specified by C<$offset> and C<$length> 1102Sync the data portion of the file specified by C<$offset> and C<$length>
1036to disk (but NOT the metadata), by calling the Linux-specific 1103to disk (but NOT the metadata), by calling the Linux-specific
1037sync_file_range call. If sync_file_range is not available or it returns 1104sync_file_range call. If sync_file_range is not available or it returns
… …
1040C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, 1107C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1041C<IO::AIO::SYNC_FILE_RANGE_WRITE> and 1108C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1042C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range 1109C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1043manpage for details. 1110manpage for details.
1044 1111
1045=item aio_pathsync $path, $callback->($status) 1112=item aio_pathsync $pathname, $callback->($status)
1046 1113
1047This request tries to open, fsync and close the given path. This is a 1114This request tries to open, fsync and close the given path. This is a
1048composite request intended to sync directories after directory operations 1115composite request intended to sync directories after directory operations
1049(E.g. rename). This might not work on all operating systems or have any 1116(E.g. rename). This might not work on all operating systems or have any
1050specific effect, but usually it makes sure that directory changes get 1117specific effect, but usually it makes sure that directory changes get
… …
1084} 1151}
1085 1152
1086=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1153=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1087 1154
1088This is a rather advanced IO::AIO call, which only works on mmap(2)ed 1155This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1089scalars (see the L<Sys::Mmap> or L<Mmap> modules for details on this, note 1156scalars (see the C<IO::AIO::mmap> function, although it also works on data
1157scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1090that the scalar must only be modified in-place while an aio operation is 1158scalar must only be modified in-place while an aio operation is pending on
1091pending on it). 1159it).
1092 1160
1093It calls the C<msync> function of your OS, if available, with the memory 1161It calls the C<msync> function of your OS, if available, with the memory
1094area starting at C<$offset> in the string and ending C<$length> bytes 1162area starting at C<$offset> in the string and ending C<$length> bytes
1095later. If C<$length> is negative, counts from the end, and if C<$length> 1163later. If C<$length> is negative, counts from the end, and if C<$length>
1096is C<undef>, then it goes till the end of the string. The flags can be 1164is C<undef>, then it goes till the end of the string. The flags can be
… …
1107as for C<aio_msync>, above, except for flags, which must be either 1175as for C<aio_msync>, above, except for flags, which must be either
1108C<0> (which reads all pages and ensures they are instantiated) or 1176C<0> (which reads all pages and ensures they are instantiated) or
1109C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and 1177C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
1110writing an octet from it, which dirties the page). 1178writing an octet from it, which dirties the page).
1111 1179
1180=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1181
1182This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1183scalars.
1184
1185It reads in all the pages of the underlying storage into memory (if any)
1186and locks them, so they are not getting swapped/paged out or removed.
1187
1188If C<$length> is undefined, then the scalar will be locked till the end.
1189
1190On systems that do not implement C<mlock>, this function returns C<-1>
1191and sets errno to C<ENOSYS>.
1192
1193Note that the corresponding C<munlock> is synchronous and is
1194documented under L<MISCELLANEOUS FUNCTIONS>.
1195
1196Example: open a file, mmap and mlock it - both will be undone when
1197C<$data> gets destroyed.
1198
1199 open my $fh, "<", $path or die "$path: $!";
1200 my $data;
1201 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1202 aio_mlock $data; # mlock in background
1203
1204=item aio_mlockall $flags, $callback->($status)
1205
1206Calls the C<mlockall> function with the given C<$flags> (a combination of
1207C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1208
1209On systems that do not implement C<mlockall>, this function returns C<-1>
1210and sets errno to C<ENOSYS>.
1211
1212Note that the corresponding C<munlockall> is synchronous and is
1213documented under L<MISCELLANEOUS FUNCTIONS>.
1214
1215Example: asynchronously lock all current and future pages into memory.
1216
1217 aio_mlockall IO::AIO::MCL_FUTURE;
1218
1112=item aio_group $callback->(...) 1219=item aio_group $callback->(...)
1113 1220
1114This is a very special aio request: Instead of doing something, it is a 1221This is a very special aio request: Instead of doing something, it is a
1115container for other aio requests, which is useful if you want to bundle 1222container for other aio requests, which is useful if you want to bundle
1116many requests into a single, composite, request with a definite callback 1223many requests into a single, composite, request with a definite callback
… …
1152like sleep and file handle readable/writable, the overhead this creates is 1259like sleep and file handle readable/writable, the overhead this creates is
1153immense (it blocks a thread for a long time) so do not use this function 1260immense (it blocks a thread for a long time) so do not use this function
1154except to put your application under artificial I/O pressure. 1261except to put your application under artificial I/O pressure.
1155 1262
1156=back 1263=back
1264
1265
1266=head2 IO::AIO::WD - multiple working directories
1267
1268Your process only has one current working directory, which is used by all
1269threads. This makes it hard to use relative paths (some other component
1270could call C<chdir> at any time, and it is hard to control when the path
1271will be used by IO::AIO).
1272
1273One solution for this is to always use absolute paths. This usually works,
1274but can be quite slow (the kernel has to walk the whole path on every
1275access), and can also be a hassle to implement.
1276
1277Newer POSIX systems have a number of functions (openat, fdopendir,
1278futimensat and so on) that make it possible to specify working directories
1279per operation.
1280
1281For portability, and because the clowns who "designed", or shall I write,
1282perpetrated this new interface were obviously half-drunk, this abstraction
1283cannot be perfect, though.
1284
1285IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1286object. This object stores the canonicalised, absolute version of the
1287path, and on systems that allow it, also a directory file descriptor.
1288
1289Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1290or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1291object and a pathname instead. If the pathname is absolute, the
1292IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative
1293to that IO::AIO::WD object.
1294
1295For example, to get a wd object for F</etc> and then stat F<passwd>
1296inside, you would write:
1297
1298 aio_wd "/etc", sub {
1299 my $etcdir = shift;
1300
1301 # although $etcdir can be undef on error, there is generally no reason
1302 # to check for errors here, as aio_stat will fail with ENOENT
1303 # when $etcdir is undef.
1304
1305 aio_stat [$etcdir, "passwd"], sub {
1306 # yay
1307 };
1308 };
1309
1310This shows that creating an IO::AIO::WD object is itself a potentially
1311blocking operation, which is why it is done asynchronously.
1312
1313As with normal pathnames, IO::AIO keeps a copy of the working directory
1314object and the pathname string, so you could write the following without
1315causing any issues due to C<$path> getting reused:
1316
1317 my $path = [$wd, undef];
1318
1319 for my $name (qw(abc def ghi)) {
1320 $path->[1] = $name;
1321 aio_stat $path, sub {
1322 # ...
1323 };
1324 }
1325
1326There are some caveats: when directories get renamed (or deleted), the
1327pathname string doesn't change, so will point to the new directory (or
1328nowhere at all), while the directory fd, if available on the system,
1329will still point to the original directory. Most functions accepting a
1330pathname will use the directory fd on newer systems, and the string on
1331older systems. Some functions (such as realpath) will always rely on the
1332string form of the pathname.
1333
1334So this fucntionality is mainly useful to get some protection against
1335C<chdir>, to easily get an absolute path out of a relative path for future
1336reference, and to speed up doing many operations in the same directory
1337(e.g. when stat'ing all files in a directory).
1338
1339The following functions implement this working directory abstraction:
1340
1341=over 4
1342
1343=item aio_wd $pathname, $callback->($wd)
1344
1345Asynchonously canonicalise the given pathname and convert it to an
1346IO::AIO::WD object representing it. If possible and supported on the
1347system, also open a directory fd to speed up pathname resolution relative
1348to this working directory.
1349
1350If something goes wrong, then C<undef> is passwd to the callback instead
1351of a working directory object and C<$!> is set appropriately. Since
1352passing C<undef> as working directory component of a pathname fails the
1353request with C<ENOENT>, there is often no need for error checking in the
1354C<aio_wd> callback, as future requests using the value will fail in the
1355expected way.
1356
1357If this call isn't available because your OS lacks it or it couldn't be
1358detected, it will be emulated by calling C<fsync> instead.
1359
1360=item IO::AIO::CWD
1361
1362This is a compiletime constant (object) that represents the process
1363current working directory.
1364
1365Specifying this object as working directory object for a pathname is as
1366if the pathname would be specified directly, without a directory object,
1367e.g., these calls are functionally identical:
1368
1369 aio_stat "somefile", sub { ... };
1370 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1371
1372=back
1373
1157 1374
1158=head2 IO::AIO::REQ CLASS 1375=head2 IO::AIO::REQ CLASS
1159 1376
1160All non-aggregate C<aio_*> functions return an object of this class when 1377All non-aggregate C<aio_*> functions return an object of this class when
1161called in non-void context. 1378called in non-void context.
… …
1339 1556
1340See C<poll_cb> for an example. 1557See C<poll_cb> for an example.
1341 1558
1342=item IO::AIO::poll_cb 1559=item IO::AIO::poll_cb
1343 1560
1344Process some outstanding events on the result pipe. You have to call this 1561Process some outstanding events on the result pipe. You have to call
1345regularly. Returns C<0> if all events could be processed, or C<-1> if it 1562this regularly. Returns C<0> if all events could be processed (or there
1346returned earlier for whatever reason. Returns immediately when no events 1563were no events to process), or C<-1> if it returned earlier for whatever
1347are outstanding. The amount of events processed depends on the settings of 1564reason. Returns immediately when no events are outstanding. The amount of
1348C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1565events processed depends on the settings of C<IO::AIO::max_poll_req> and
1566C<IO::AIO::max_poll_time>.
1349 1567
1350If not all requests were processed for whatever reason, the filehandle 1568If not all requests were processed for whatever reason, the filehandle
1351will still be ready when C<poll_cb> returns, so normally you don't have to 1569will still be ready when C<poll_cb> returns, so normally you don't have to
1352do anything special to have it called later. 1570do anything special to have it called later.
1571
1572Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1573ready, it can be beneficial to call this function from loops which submit
1574a lot of requests, to make sure the results get processed when they become
1575available and not just when the loop is finished and the event loop takes
1576over again. This function returns very fast when there are no outstanding
1577requests.
1353 1578
1354Example: Install an Event watcher that automatically calls 1579Example: Install an Event watcher that automatically calls
1355IO::AIO::poll_cb with high priority (more examples can be found in the 1580IO::AIO::poll_cb with high priority (more examples can be found in the
1356SYNOPSIS section, at the top of this document): 1581SYNOPSIS section, at the top of this document):
1357 1582
… …
1459 1684
1460Under normal circumstances you don't need to call this function. 1685Under normal circumstances you don't need to call this function.
1461 1686
1462=item IO::AIO::max_idle $nthreads 1687=item IO::AIO::max_idle $nthreads
1463 1688
1464Limit the number of threads (default: 4) that are allowed to idle (i.e., 1689Limit the number of threads (default: 4) that are allowed to idle
1465threads that did not get a request to process within 10 seconds). That 1690(i.e., threads that did not get a request to process within the idle
1466means if a thread becomes idle while C<$nthreads> other threads are also 1691timeout (default: 10 seconds). That means if a thread becomes idle while
1467idle, it will free its resources and exit. 1692C<$nthreads> other threads are also idle, it will free its resources and
1693exit.
1468 1694
1469This is useful when you allow a large number of threads (e.g. 100 or 1000) 1695This is useful when you allow a large number of threads (e.g. 100 or 1000)
1470to allow for extremely high load situations, but want to free resources 1696to allow for extremely high load situations, but want to free resources
1471under normal circumstances (1000 threads can easily consume 30MB of RAM). 1697under normal circumstances (1000 threads can easily consume 30MB of RAM).
1472 1698
1473The default is probably ok in most situations, especially if thread 1699The default is probably ok in most situations, especially if thread
1474creation is fast. If thread creation is very slow on your system you might 1700creation is fast. If thread creation is very slow on your system you might
1475want to use larger values. 1701want to use larger values.
1476 1702
1703=item IO::AIO::idle_timeout $seconds
1704
1705Sets the minimum idle timeout (default 10) after which worker threads are
1706allowed to exit. SEe C<IO::AIO::max_idle>.
1707
1477=item IO::AIO::max_outstanding $maxreqs 1708=item IO::AIO::max_outstanding $maxreqs
1709
1710Sets the maximum number of outstanding requests to C<$nreqs>. If
1711you do queue up more than this number of requests, the next call to
1712C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1713C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1714longer exceeded.
1715
1716In other words, this setting does not enforce a queue limit, but can be
1717used to make poll functions block if the limit is exceeded.
1478 1718
1479This is a very bad function to use in interactive programs because it 1719This is a very bad function to use in interactive programs because it
1480blocks, and a bad way to reduce concurrency because it is inexact: Better 1720blocks, and a bad way to reduce concurrency because it is inexact: Better
1481use an C<aio_group> together with a feed callback. 1721use an C<aio_group> together with a feed callback.
1482 1722
1483Sets the maximum number of outstanding requests to C<$nreqs>. If you 1723It's main use is in scripts without an event loop - when you want to stat
1484do queue up more than this number of requests, the next call to the 1724a lot of files, you can write somehting like this:
1485C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1486function will block until the limit is no longer exceeded.
1487 1725
1488The default value is very large, so there is no practical limit on the 1726 IO::AIO::max_outstanding 32;
1489number of outstanding requests.
1490 1727
1491You can still queue as many requests as you want. Therefore, 1728 for my $path (...) {
1492C<max_outstanding> is mainly useful in simple scripts (with low values) or 1729 aio_stat $path , ...;
1493as a stop gap to shield against fatal memory overflow (with large values). 1730 IO::AIO::poll_cb;
1731 }
1732
1733 IO::AIO::flush;
1734
1735The call to C<poll_cb> inside the loop will normally return instantly, but
1736as soon as more thna C<32> reqeusts are in-flight, it will block until
1737some requests have been handled. This keeps the loop from pushing a large
1738number of C<aio_stat> requests onto the queue.
1739
1740The default value for C<max_outstanding> is very large, so there is no
1741practical limit on the number of outstanding requests.
1494 1742
1495=back 1743=back
1496 1744
1497=head3 STATISTICAL INFORMATION 1745=head3 STATISTICAL INFORMATION
1498 1746
… …
1536 1784
1537Returns the number of bytes copied, or C<-1> on error. 1785Returns the number of bytes copied, or C<-1> on error.
1538 1786
1539=item IO::AIO::fadvise $fh, $offset, $len, $advice 1787=item IO::AIO::fadvise $fh, $offset, $len, $advice
1540 1788
1541Simply calls the C<posix_fadvise> function (see it's 1789Simply calls the C<posix_fadvise> function (see its
1542manpage for details). The following advice constants are 1790manpage for details). The following advice constants are
1543avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>, 1791available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1544C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>, 1792C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1545C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>. 1793C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1546 1794
1547On systems that do not implement C<posix_fadvise>, this function returns 1795On systems that do not implement C<posix_fadvise>, this function returns
1548ENOSYS, otherwise the return value of C<posix_fadvise>. 1796ENOSYS, otherwise the return value of C<posix_fadvise>.
1549 1797
1550=item IO::AIO::mlockall $flags 1798=item IO::AIO::madvise $scalar, $offset, $len, $advice
1551 1799
1552Calls the C<mlockall> function with the given C<$flags> (a combination of 1800Simply calls the C<posix_madvise> function (see its
1553C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL__FUTURE>). 1801manpage for details). The following advice constants are
1802available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1803C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1554 1804
1805On systems that do not implement C<posix_madvise>, this function returns
1806ENOSYS, otherwise the return value of C<posix_madvise>.
1807
1808=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1809
1810Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1811$scalar (see its manpage for details). The following protect
1812constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1813C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1814
1555On systems that do not implement C<mlockall>, this function returns 1815On systems that do not implement C<mprotect>, this function returns
1556ENOSYS, otherwise the return value of C<mlockall>. 1816ENOSYS, otherwise the return value of C<mprotect>.
1817
1818=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1819
1820Memory-maps a file (or anonymous memory range) and attaches it to the
1821given C<$scalar>, which will act like a string scalar.
1822
1823The only operations allowed on the scalar are C<substr>/C<vec> that don't
1824change the string length, and most read-only operations such as copying it
1825or searching it with regexes and so on.
1826
1827Anything else is unsafe and will, at best, result in memory leaks.
1828
1829The memory map associated with the C<$scalar> is automatically removed
1830when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
1831C<IO::AIO::munmap> functions are called.
1832
1833This calls the C<mmap>(2) function internally. See your system's manual
1834page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1835
1836The C<$length> must be larger than zero and smaller than the actual
1837filesize.
1838
1839C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1840C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1841
1842C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
1843C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
1844not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
1845(which is set to C<MAP_ANON> if your system only provides this
1846constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
1847C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1848C<IO::AIO::MAP_NONBLOCK>
1849
1850If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1851
1852C<$offset> is the offset from the start of the file - it generally must be
1853a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1854
1855Example:
1856
1857 use Digest::MD5;
1858 use IO::AIO;
1859
1860 open my $fh, "<verybigfile"
1861 or die "$!";
1862
1863 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1864 or die "verybigfile: $!";
1865
1866 my $fast_md5 = md5 $data;
1867
1868=item IO::AIO::munmap $scalar
1869
1870Removes a previous mmap and undefines the C<$scalar>.
1871
1872=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1873
1874Calls the C<munlock> function, undoing the effects of a previous
1875C<aio_mlock> call (see its description for details).
1557 1876
1558=item IO::AIO::munlockall 1877=item IO::AIO::munlockall
1559 1878
1560Calls the C<munlockall> function. 1879Calls the C<munlockall> function.
1561 1880
… …
1603 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 1922 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1604 \&IO::AIO::poll_cb); 1923 \&IO::AIO::poll_cb);
1605 1924
1606=head2 FORK BEHAVIOUR 1925=head2 FORK BEHAVIOUR
1607 1926
1608This module should do "the right thing" when the process using it forks: 1927Usage of pthreads in a program changes the semantics of fork
1928considerably. Specifically, only async-safe functions can be called after
1929fork. Perl doesn't know about this, so in general, you cannot call fork
1930with defined behaviour in perl if pthreads are involved. IO::AIO uses
1931pthreads, so this applies, but many other extensions and (for inexplicable
1932reasons) perl itself often is linked against pthreads, so this limitation
1933applies to quite a lot of perls.
1609 1934
1610Before the fork, IO::AIO enters a quiescent state where no requests 1935This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1611can be added in other threads and no results will be processed. After 1936only works in the process that loaded it. Forking is fully supported, but
1612the fork the parent simply leaves the quiescent state and continues 1937using IO::AIO in the child is not.
1613request/result processing, while the child frees the request/result queue
1614(so that the requests started before the fork will only be handled in the
1615parent). Threads will be started on demand until the limit set in the
1616parent process has been reached again.
1617 1938
1618In short: the parent will, after a short pause, continue as if fork had 1939You might get around by not I<using> IO::AIO before (or after)
1619not been called, while the child will act as if IO::AIO has not been used 1940forking. You could also try to call the L<IO::AIO::reinit> function in the
1620yet. 1941child:
1942
1943=over 4
1944
1945=item IO::AIO::reinit
1946
1947Abandons all current requests and I/O threads and simply reinitialises all
1948data structures. This is not an operation supported by any standards, but
1949happens to work on GNU/Linux and some newer BSD systems.
1950
1951The only reasonable use for this function is to call it after forking, if
1952C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
1953the process will result in undefined behaviour. Calling it at any time
1954will also result in any undefined (by POSIX) behaviour.
1955
1956=back
1621 1957
1622=head2 MEMORY USAGE 1958=head2 MEMORY USAGE
1623 1959
1624Per-request usage: 1960Per-request usage:
1625 1961

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