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Revision 1.183 by root, Sun Sep 12 03:40:05 2010 UTC vs.
Revision 1.219 by root, Tue Mar 27 18:54:45 2012 UTC

… …
168use common::sense; 168use common::sense;
169 169
170use base 'Exporter'; 170use base 'Exporter';
171 171
172BEGIN { 172BEGIN {
173 our $VERSION = '3.65'; 173 our $VERSION = '4.12';
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_mlock aio_mlockall 183 aio_msync aio_mtouch aio_mlock aio_mlockall
183 aio_statvfs); 184 aio_statvfs
185 aio_wd);
184 186
185 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
186 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
187 min_parallel max_parallel max_idle 189 min_parallel max_parallel max_idle idle_timeout
188 nreqs nready npending nthreads 190 nreqs nready npending nthreads
189 max_poll_time max_poll_reqs 191 max_poll_time max_poll_reqs
190 sendfile fadvise madvise 192 sendfile fadvise madvise
191 mmap munmap munlock munlockall); 193 mmap munmap munlock munlockall);
192 194
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204 206
205This section simply lists the prototypes of the most important functions 207This section simply lists the prototypes of the most important functions
206for quick reference. See the following sections for function-by-function 208for quick reference. See the following sections for function-by-function
207documentation. 209documentation.
208 210
211 aio_wd $pathname, $callback->($wd)
209 aio_open $pathname, $flags, $mode, $callback->($fh) 212 aio_open $pathname, $flags, $mode, $callback->($fh)
210 aio_close $fh, $callback->($status) 213 aio_close $fh, $callback->($status)
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)
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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)
220 aio_truncate $fh_or_path, $offset, $callback->($status) 223 aio_truncate $fh_or_path, $offset, $callback->($status)
221 aio_chmod $fh_or_path, $mode, $callback->($status) 224 aio_chmod $fh_or_path, $mode, $callback->($status)
222 aio_unlink $pathname, $callback->($status) 225 aio_unlink $pathname, $callback->($status)
223 aio_mknod $path, $mode, $dev, $callback->($status) 226 aio_mknod $pathname, $mode, $dev, $callback->($status)
224 aio_link $srcpath, $dstpath, $callback->($status) 227 aio_link $srcpath, $dstpath, $callback->($status)
225 aio_symlink $srcpath, $dstpath, $callback->($status) 228 aio_symlink $srcpath, $dstpath, $callback->($status)
226 aio_readlink $path, $callback->($link) 229 aio_readlink $pathname, $callback->($link)
230 aio_realpath $pathname, $callback->($link)
227 aio_rename $srcpath, $dstpath, $callback->($status) 231 aio_rename $srcpath, $dstpath, $callback->($status)
228 aio_mkdir $pathname, $mode, $callback->($status) 232 aio_mkdir $pathname, $mode, $callback->($status)
229 aio_rmdir $pathname, $callback->($status) 233 aio_rmdir $pathname, $callback->($status)
230 aio_readdir $pathname, $callback->($entries) 234 aio_readdir $pathname, $callback->($entries)
231 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 235 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 236 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 237 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
238 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
234 aio_load $path, $data, $callback->($status) 239 aio_load $pathname, $data, $callback->($status)
235 aio_copy $srcpath, $dstpath, $callback->($status) 240 aio_copy $srcpath, $dstpath, $callback->($status)
236 aio_move $srcpath, $dstpath, $callback->($status) 241 aio_move $srcpath, $dstpath, $callback->($status)
237 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238 aio_rmtree $path, $callback->($status) 242 aio_rmtree $pathname, $callback->($status)
239 aio_sync $callback->($status) 243 aio_sync $callback->($status)
244 aio_syncfs $fh, $callback->($status)
240 aio_fsync $fh, $callback->($status) 245 aio_fsync $fh, $callback->($status)
241 aio_fdatasync $fh, $callback->($status) 246 aio_fdatasync $fh, $callback->($status)
242 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 247 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243 aio_pathsync $path, $callback->($status) 248 aio_pathsync $pathname, $callback->($status)
244 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 249 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
245 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 250 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 251 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247 aio_mlockall $flags, $callback->($status) 252 aio_mlockall $flags, $callback->($status)
248 aio_group $callback->(...) 253 aio_group $callback->(...)
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258 IO::AIO::max_poll_reqs $nreqs 263 IO::AIO::max_poll_reqs $nreqs
259 IO::AIO::max_poll_time $seconds 264 IO::AIO::max_poll_time $seconds
260 IO::AIO::min_parallel $nthreads 265 IO::AIO::min_parallel $nthreads
261 IO::AIO::max_parallel $nthreads 266 IO::AIO::max_parallel $nthreads
262 IO::AIO::max_idle $nthreads 267 IO::AIO::max_idle $nthreads
268 IO::AIO::idle_timeout $seconds
263 IO::AIO::max_outstanding $maxreqs 269 IO::AIO::max_outstanding $maxreqs
264 IO::AIO::nreqs 270 IO::AIO::nreqs
265 IO::AIO::nready 271 IO::AIO::nready
266 IO::AIO::npending 272 IO::AIO::npending
267 273
268 IO::AIO::sendfile $ofh, $ifh, $offset, $count 274 IO::AIO::sendfile $ofh, $ifh, $offset, $count
269 IO::AIO::fadvise $fh, $offset, $len, $advice 275 IO::AIO::fadvise $fh, $offset, $len, $advice
276 IO::AIO::madvise $scalar, $offset, $length, $advice
277 IO::AIO::mprotect $scalar, $offset, $length, $protect
270 IO::AIO::munlock $scalar, $offset = 0, $length = undef 278 IO::AIO::munlock $scalar, $offset = 0, $length = undef
271 IO::AIO::munlockall 279 IO::AIO::munlockall
272 280
273=head2 AIO REQUEST FUNCTIONS 281=head2 API NOTES
274 282
275All the C<aio_*> calls are more or less thin wrappers around the syscall 283All the C<aio_*> calls are more or less thin wrappers around the syscall
276with the same name (sans C<aio_>). The arguments are similar or identical, 284with the same name (sans C<aio_>). The arguments are similar or identical,
277and they all accept an additional (and optional) C<$callback> argument 285and they all accept an additional (and optional) C<$callback> argument
278which must be a code reference. This code reference will get called with 286which must be a code reference. This code reference will be called after
279the syscall return code (e.g. most syscalls return C<-1> on error, unlike 287the syscall has been executed in an asynchronous fashion. The results
280perl, which usually delivers "false") as its sole argument after the given 288of the request will be passed as arguments to the callback (and, if an
281syscall has been executed asynchronously. 289error occured, in C<$!>) - for most requests the syscall return code (e.g.
290most syscalls return C<-1> on error, unlike perl, which usually delivers
291"false").
292
293Some requests (such as C<aio_readdir>) pass the actual results and
294communicate failures by passing C<undef>.
282 295
283All functions expecting a filehandle keep a copy of the filehandle 296All functions expecting a filehandle keep a copy of the filehandle
284internally until the request has finished. 297internally until the request has finished.
285 298
286All functions return request objects of type L<IO::AIO::REQ> that allow 299All functions return request objects of type L<IO::AIO::REQ> that allow
287further manipulation of those requests while they are in-flight. 300further manipulation of those requests while they are in-flight.
288 301
289The pathnames you pass to these routines I<must> be absolute and 302The pathnames you pass to these routines I<should> be absolute. The
290encoded as octets. The reason for the former is that at the time the 303reason for this is that at the time the request is being executed, the
291request is being executed, the current working directory could have 304current working directory could have changed. Alternatively, you can
292changed. Alternatively, you can make sure that you never change the 305make sure that you never change the current working directory anywhere
293current working directory anywhere in the program and then use relative 306in the program and then use relative paths. You can also take advantage
294paths. 307of IO::AIOs working directory abstraction, that lets you specify paths
308relative to some previously-opened "working directory object" - see the
309description of the C<IO::AIO::WD> class later in this document.
295 310
296To encode pathnames as octets, either make sure you either: a) always pass 311To encode pathnames as octets, either make sure you either: a) always pass
297in filenames you got from outside (command line, readdir etc.) without 312in filenames you got from outside (command line, readdir etc.) without
298tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 313tinkering, b) are in your native filesystem encoding, c) use the Encode
299your pathnames to the locale (or other) encoding in effect in the user 314module and encode your pathnames to the locale (or other) encoding in
300environment, d) use Glib::filename_from_unicode on unicode filenames or e) 315effect in the user environment, d) use Glib::filename_from_unicode on
301use something else to ensure your scalar has the correct contents. 316unicode filenames or e) use something else to ensure your scalar has the
317correct contents.
302 318
303This works, btw. independent of the internal UTF-8 bit, which IO::AIO 319This works, btw. independent of the internal UTF-8 bit, which IO::AIO
304handles correctly whether it is set or not. 320handles correctly whether it is set or not.
321
322=head2 AIO REQUEST FUNCTIONS
305 323
306=over 4 324=over 4
307 325
308=item $prev_pri = aioreq_pri [$pri] 326=item $prev_pri = aioreq_pri [$pri]
309 327
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365 } else { 383 } else {
366 die "open failed: $!\n"; 384 die "open failed: $!\n";
367 } 385 }
368 }; 386 };
369 387
388In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
389C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
390following POSIX and non-POSIX constants are available (missing ones on
391your system are, as usual, C<0>):
392
393C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
394C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
395C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
396
370 397
371=item aio_close $fh, $callback->($status) 398=item aio_close $fh, $callback->($status)
372 399
373Asynchronously close a file and call the callback with the result 400Asynchronously close a file and call the callback with the result
374code. 401code.
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424 451
425Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 452Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
426reading at byte offset C<$in_offset>, and starts writing at the current 453reading at byte offset C<$in_offset>, and starts writing at the current
427file offset of C<$out_fh>. Because of that, it is not safe to issue more 454file offset of C<$out_fh>. Because of that, it is not safe to issue more
428than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 455than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
429other. 456other. The same C<$in_fh> works fine though, as this function does not
457move or use the file offset of C<$in_fh>.
430 458
459Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
460are written, and there is no way to find out how many more bytes have been
461read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
462number of bytes written to C<$out_fh>. Only if the result value equals
463C<$length> one can assume that C<$length> bytes have been read.
464
465Unlike with other C<aio_> functions, it makes a lot of sense to use
466C<aio_sendfile> on non-blocking sockets, as long as one end (typically
467the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
468the socket I/O will be non-blocking. Note, however, that you can run
469into a trap where C<aio_sendfile> reads some data with readahead, then
470fails to write all data, and when the socket is ready the next time, the
471data in the cache is already lost, forcing C<aio_sendfile> to again hit
472the disk. Explicit C<aio_read> + C<aio_write> let's you better control
473resource usage.
474
431This call tries to make use of a native C<sendfile> syscall to provide 475This call tries to make use of a native C<sendfile>-like syscall to
432zero-copy operation. For this to work, C<$out_fh> should refer to a 476provide zero-copy operation. For this to work, C<$out_fh> should refer to
433socket, and C<$in_fh> should refer to an mmap'able file. 477a socket, and C<$in_fh> should refer to an mmap'able file.
434 478
435If a native sendfile cannot be found or it fails with C<ENOSYS>, 479If a native sendfile cannot be found or it fails with C<ENOSYS>,
436C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>, 480C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
437it will be emulated, so you can call C<aio_sendfile> on any type of 481C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
438filehandle regardless of the limitations of the operating system. 482type of filehandle regardless of the limitations of the operating system.
439 483
440Please note, however, that C<aio_sendfile> can read more bytes from 484As native sendfile syscalls (as practically any non-POSIX interface hacked
441C<$in_fh> than are written, and there is no way to find out how many 485together in a hurry to improve benchmark numbers) tend to be rather buggy
442bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 486on many systems, this implementation tries to work around some known bugs
443provides the number of bytes written to C<$out_fh>. Only if the result 487in Linux and FreeBSD kernels (probably others, too), but that might fail,
444value equals C<$length> one can assume that C<$length> bytes have been 488so you really really should check the return value of C<aio_sendfile> -
445read. 489fewre bytes than expected might have been transferred.
446 490
447 491
448=item aio_readahead $fh,$offset,$length, $callback->($retval) 492=item aio_readahead $fh,$offset,$length, $callback->($retval)
449 493
450C<aio_readahead> populates the page cache with data from a file so that 494C<aio_readahead> populates the page cache with data from a file so that
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472for an explanation. 516for an explanation.
473 517
474Currently, the stats are always 64-bit-stats, i.e. instead of returning an 518Currently, the stats are always 64-bit-stats, i.e. instead of returning an
475error when stat'ing a large file, the results will be silently truncated 519error when stat'ing a large file, the results will be silently truncated
476unless perl itself is compiled with large file support. 520unless perl itself is compiled with large file support.
521
522To help interpret the mode and dev/rdev stat values, IO::AIO offers the
523following constants and functions (if not implemented, the constants will
524be C<0> and the functions will either C<croak> or fall back on traditional
525behaviour).
526
527C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
528C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
529C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
477 530
478Example: Print the length of F</etc/passwd>: 531Example: Print the length of F</etc/passwd>:
479 532
480 aio_stat "/etc/passwd", sub { 533 aio_stat "/etc/passwd", sub {
481 $_[0] and die "stat failed: $!"; 534 $_[0] and die "stat failed: $!";
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573 626
574Asynchronously unlink (delete) a file and call the callback with the 627Asynchronously unlink (delete) a file and call the callback with the
575result code. 628result code.
576 629
577 630
578=item aio_mknod $path, $mode, $dev, $callback->($status) 631=item aio_mknod $pathname, $mode, $dev, $callback->($status)
579 632
580[EXPERIMENTAL] 633[EXPERIMENTAL]
581 634
582Asynchronously create a device node (or fifo). See mknod(2). 635Asynchronously create a device node (or fifo). See mknod(2).
583 636
584The only (POSIX-) portable way of calling this function is: 637The only (POSIX-) portable way of calling this function is:
585 638
586 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 639 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
587 640
641See C<aio_stat> for info about some potentially helpful extra constants
642and functions.
588 643
589=item aio_link $srcpath, $dstpath, $callback->($status) 644=item aio_link $srcpath, $dstpath, $callback->($status)
590 645
591Asynchronously create a new link to the existing object at C<$srcpath> at 646Asynchronously create a new link to the existing object at C<$srcpath> at
592the path C<$dstpath> and call the callback with the result code. 647the path C<$dstpath> and call the callback with the result code.
… …
596 651
597Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 652Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
598the path C<$dstpath> and call the callback with the result code. 653the path C<$dstpath> and call the callback with the result code.
599 654
600 655
601=item aio_readlink $path, $callback->($link) 656=item aio_readlink $pathname, $callback->($link)
602 657
603Asynchronously read the symlink specified by C<$path> and pass it to 658Asynchronously read the symlink specified by C<$path> and pass it to
604the callback. If an error occurs, nothing or undef gets passed to the 659the callback. If an error occurs, nothing or undef gets passed to the
605callback. 660callback.
606 661
607 662
663=item aio_realpath $pathname, $callback->($path)
664
665Asynchronously make the path absolute and resolve any symlinks in
666C<$path>. The resulting path only consists of directories (Same as
667L<Cwd::realpath>).
668
669This request can be used to get the absolute path of the current working
670directory by passing it a path of F<.> (a single dot).
671
672
608=item aio_rename $srcpath, $dstpath, $callback->($status) 673=item aio_rename $srcpath, $dstpath, $callback->($status)
609 674
610Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 675Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
611rename(2) and call the callback with the result code. 676rename(2) and call the callback with the result code.
612 677
… …
634array-ref with the filenames. 699array-ref with the filenames.
635 700
636 701
637=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) 702=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
638 703
639Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune 704Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
640behaviour and output format. In case of an error, C<$entries> will be 705tune behaviour and output format. In case of an error, C<$entries> will be
641C<undef>. 706C<undef>.
642 707
643The flags are a combination of the following constants, ORed together (the 708The flags are a combination of the following constants, ORed together (the
644flags will also be passed to the callback, possibly modified): 709flags will also be passed to the callback, possibly modified):
645 710
646=over 4 711=over 4
647 712
648=item IO::AIO::READDIR_DENTS 713=item IO::AIO::READDIR_DENTS
649 714
650When this flag is off, then the callback gets an arrayref with of names 715When this flag is off, then the callback gets an arrayref consisting of
651only (as with C<aio_readdir>), otherwise it gets an arrayref with 716names only (as with C<aio_readdir>), otherwise it gets an arrayref with
652C<[$name, $type, $inode]> arrayrefs, each describing a single directory 717C<[$name, $type, $inode]> arrayrefs, each describing a single directory
653entry in more detail. 718entry in more detail.
654 719
655C<$name> is the name of the entry. 720C<$name> is the name of the entry.
656 721
… …
669systems that do not deliver the inode information. 734systems that do not deliver the inode information.
670 735
671=item IO::AIO::READDIR_DIRS_FIRST 736=item IO::AIO::READDIR_DIRS_FIRST
672 737
673When this flag is set, then the names will be returned in an order where 738When this flag is set, then the names will be returned in an order where
674likely directories come first. This is useful when you need to quickly 739likely directories come first, in optimal stat order. This is useful when
675find directories, or you want to find all directories while avoiding to 740you need to quickly find directories, or you want to find all directories
676stat() each entry. 741while avoiding to stat() each entry.
677 742
678If the system returns type information in readdir, then this is used 743If the system returns type information in readdir, then this is used
679to find directories directly. Otherwise, likely directories are files 744to find directories directly. Otherwise, likely directories are names
680beginning with ".", or otherwise files with no dots, of which files with 745beginning with ".", or otherwise names with no dots, of which names with
681short names are tried first. 746short names are tried first.
682 747
683=item IO::AIO::READDIR_STAT_ORDER 748=item IO::AIO::READDIR_STAT_ORDER
684 749
685When this flag is set, then the names will be returned in an order 750When this flag is set, then the names will be returned in an order
… …
692 757
693=item IO::AIO::READDIR_FOUND_UNKNOWN 758=item IO::AIO::READDIR_FOUND_UNKNOWN
694 759
695This flag should not be set when calling C<aio_readdirx>. Instead, it 760This flag should not be set when calling C<aio_readdirx>. Instead, it
696is being set by C<aio_readdirx>, when any of the C<$type>'s found were 761is being set by C<aio_readdirx>, when any of the C<$type>'s found were
697C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all 762C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
698C<$type>'s are known, which can be used to speed up some algorithms. 763C<$type>'s are known, which can be used to speed up some algorithms.
699 764
700=back 765=back
701 766
702 767
703=item aio_load $path, $data, $callback->($status) 768=item aio_load $pathname, $data, $callback->($status)
704 769
705This is a composite request that tries to fully load the given file into 770This is a composite request that tries to fully load the given file into
706memory. Status is the same as with aio_read. 771memory. Status is the same as with aio_read.
707 772
708=cut 773=cut
… …
830 if ($_[0] && $! == EXDEV) { 895 if ($_[0] && $! == EXDEV) {
831 aioreq_pri $pri; 896 aioreq_pri $pri;
832 add $grp aio_copy $src, $dst, sub { 897 add $grp aio_copy $src, $dst, sub {
833 $grp->result ($_[0]); 898 $grp->result ($_[0]);
834 899
835 if (!$_[0]) { 900 unless ($_[0]) {
836 aioreq_pri $pri; 901 aioreq_pri $pri;
837 add $grp aio_unlink $src; 902 add $grp aio_unlink $src;
838 } 903 }
839 }; 904 };
840 } else { 905 } else {
… …
843 }; 908 };
844 909
845 $grp 910 $grp
846} 911}
847 912
848=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 913=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
849 914
850Scans a directory (similar to C<aio_readdir>) but additionally tries to 915Scans a directory (similar to C<aio_readdir>) but additionally tries to
851efficiently separate the entries of directory C<$path> into two sets of 916efficiently separate the entries of directory C<$path> into two sets of
852names, directories you can recurse into (directories), and ones you cannot 917names, directories you can recurse into (directories), and ones you cannot
853recurse into (everything else, including symlinks to directories). 918recurse into (everything else, including symlinks to directories).
… …
884Then entries will be sorted into likely directories a non-initial dot 949Then entries will be sorted into likely directories a non-initial dot
885currently) and likely non-directories (see C<aio_readdirx>). Then every 950currently) and likely non-directories (see C<aio_readdirx>). Then every
886entry plus an appended C</.> will be C<stat>'ed, likely directories first, 951entry plus an appended C</.> will be C<stat>'ed, likely directories first,
887in order of their inode numbers. If that succeeds, it assumes that the 952in order of their inode numbers. If that succeeds, it assumes that the
888entry is a directory or a symlink to directory (which will be checked 953entry is a directory or a symlink to directory (which will be checked
889seperately). This is often faster than stat'ing the entry itself because 954separately). This is often faster than stat'ing the entry itself because
890filesystems might detect the type of the entry without reading the inode 955filesystems might detect the type of the entry without reading the inode
891data (e.g. ext2fs filetype feature), even on systems that cannot return 956data (e.g. ext2fs filetype feature), even on systems that cannot return
892the filetype information on readdir. 957the filetype information on readdir.
893 958
894If the known number of directories (link count - 2) has been reached, the 959If the known number of directories (link count - 2) has been reached, the
… …
910 975
911 my $grp = aio_group $cb; 976 my $grp = aio_group $cb;
912 977
913 $maxreq = 4 if $maxreq <= 0; 978 $maxreq = 4 if $maxreq <= 0;
914 979
915 # stat once 980 # get a wd object
916 aioreq_pri $pri; 981 aioreq_pri $pri;
917 add $grp aio_stat $path, sub { 982 add $grp aio_wd $path, sub {
983 $_[0]
918 return $grp->result () if $_[0]; 984 or return $grp->result ();
919 my $now = time;
920 my $hash1 = join ":", (stat _)[0,1,3,7,9];
921 985
922 # read the directory entries 986 my $wd = [shift, "."];
987
988 # stat once
923 aioreq_pri $pri; 989 aioreq_pri $pri;
924 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { 990 add $grp aio_stat $wd, sub {
925 my $entries = shift
926 or return $grp->result (); 991 return $grp->result () if $_[0];
992 my $now = time;
993 my $hash1 = join ":", (stat _)[0,1,3,7,9];
927 994
928 # stat the dir another time 995 # read the directory entries
929 aioreq_pri $pri; 996 aioreq_pri $pri;
997 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
998 my $entries = shift
999 or return $grp->result ();
1000
1001 # stat the dir another time
1002 aioreq_pri $pri;
930 add $grp aio_stat $path, sub { 1003 add $grp aio_stat $wd, sub {
931 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1004 my $hash2 = join ":", (stat _)[0,1,3,7,9];
932 1005
933 my $ndirs; 1006 my $ndirs;
934 1007
935 # take the slow route if anything looks fishy 1008 # take the slow route if anything looks fishy
936 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1009 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
937 $ndirs = -1; 1010 $ndirs = -1;
938 } else { 1011 } else {
939 # if nlink == 2, we are finished 1012 # if nlink == 2, we are finished
940 # for non-posix-fs's, we rely on nlink < 2 1013 # for non-posix-fs's, we rely on nlink < 2
941 $ndirs = (stat _)[3] - 2 1014 $ndirs = (stat _)[3] - 2
942 or return $grp->result ([], $entries); 1015 or return $grp->result ([], $entries);
943 } 1016 }
944 1017
945 my (@dirs, @nondirs); 1018 my (@dirs, @nondirs);
946 1019
947 my $statgrp = add $grp aio_group sub { 1020 my $statgrp = add $grp aio_group sub {
948 $grp->result (\@dirs, \@nondirs); 1021 $grp->result (\@dirs, \@nondirs);
949 }; 1022 };
950 1023
951 limit $statgrp $maxreq; 1024 limit $statgrp $maxreq;
952 feed $statgrp sub { 1025 feed $statgrp sub {
953 return unless @$entries; 1026 return unless @$entries;
954 my $entry = shift @$entries; 1027 my $entry = shift @$entries;
955 1028
956 aioreq_pri $pri; 1029 aioreq_pri $pri;
1030 $wd->[1] = "$entry/.";
957 add $statgrp aio_stat "$path/$entry/.", sub { 1031 add $statgrp aio_stat $wd, sub {
958 if ($_[0] < 0) { 1032 if ($_[0] < 0) {
959 push @nondirs, $entry; 1033 push @nondirs, $entry;
960 } else { 1034 } else {
961 # need to check for real directory 1035 # need to check for real directory
962 aioreq_pri $pri; 1036 aioreq_pri $pri;
1037 $wd->[1] = $entry;
963 add $statgrp aio_lstat "$path/$entry", sub { 1038 add $statgrp aio_lstat $wd, sub {
964 if (-d _) { 1039 if (-d _) {
965 push @dirs, $entry; 1040 push @dirs, $entry;
966 1041
967 unless (--$ndirs) { 1042 unless (--$ndirs) {
968 push @nondirs, @$entries; 1043 push @nondirs, @$entries;
969 feed $statgrp; 1044 feed $statgrp;
1045 }
1046 } else {
1047 push @nondirs, $entry;
970 } 1048 }
971 } else {
972 push @nondirs, $entry;
973 } 1049 }
974 } 1050 }
975 } 1051 };
976 }; 1052 };
977 }; 1053 };
978 }; 1054 };
979 }; 1055 };
980 }; 1056 };
981 1057
982 $grp 1058 $grp
983} 1059}
984 1060
985=item aio_rmtree $path, $callback->($status) 1061=item aio_rmtree $pathname, $callback->($status)
986 1062
987Delete a directory tree starting (and including) C<$path>, return the 1063Delete a directory tree starting (and including) C<$path>, return the
988status of the final C<rmdir> only. This is a composite request that 1064status of the final C<rmdir> only. This is a composite request that
989uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1065uses C<aio_scandir> to recurse into and rmdir directories, and unlink
990everything else. 1066everything else.
… …
1032callback with the fdatasync result code. 1108callback with the fdatasync result code.
1033 1109
1034If this call isn't available because your OS lacks it or it couldn't be 1110If this call isn't available because your OS lacks it or it couldn't be
1035detected, it will be emulated by calling C<fsync> instead. 1111detected, it will be emulated by calling C<fsync> instead.
1036 1112
1113=item aio_syncfs $fh, $callback->($status)
1114
1115Asynchronously call the syncfs syscall to sync the filesystem associated
1116to the given filehandle and call the callback with the syncfs result
1117code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1118errno to C<ENOSYS> nevertheless.
1119
1037=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1120=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1038 1121
1039Sync the data portion of the file specified by C<$offset> and C<$length> 1122Sync the data portion of the file specified by C<$offset> and C<$length>
1040to disk (but NOT the metadata), by calling the Linux-specific 1123to disk (but NOT the metadata), by calling the Linux-specific
1041sync_file_range call. If sync_file_range is not available or it returns 1124sync_file_range call. If sync_file_range is not available or it returns
… …
1044C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, 1127C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1045C<IO::AIO::SYNC_FILE_RANGE_WRITE> and 1128C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1046C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range 1129C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1047manpage for details. 1130manpage for details.
1048 1131
1049=item aio_pathsync $path, $callback->($status) 1132=item aio_pathsync $pathname, $callback->($status)
1050 1133
1051This request tries to open, fsync and close the given path. This is a 1134This request tries to open, fsync and close the given path. This is a
1052composite request intended to sync directories after directory operations 1135composite request intended to sync directories after directory operations
1053(E.g. rename). This might not work on all operating systems or have any 1136(E.g. rename). This might not work on all operating systems or have any
1054specific effect, but usually it makes sure that directory changes get 1137specific effect, but usually it makes sure that directory changes get
… …
1197immense (it blocks a thread for a long time) so do not use this function 1280immense (it blocks a thread for a long time) so do not use this function
1198except to put your application under artificial I/O pressure. 1281except to put your application under artificial I/O pressure.
1199 1282
1200=back 1283=back
1201 1284
1285
1286=head2 IO::AIO::WD - multiple working directories
1287
1288Your process only has one current working directory, which is used by all
1289threads. This makes it hard to use relative paths (some other component
1290could call C<chdir> at any time, and it is hard to control when the path
1291will be used by IO::AIO).
1292
1293One solution for this is to always use absolute paths. This usually works,
1294but can be quite slow (the kernel has to walk the whole path on every
1295access), and can also be a hassle to implement.
1296
1297Newer POSIX systems have a number of functions (openat, fdopendir,
1298futimensat and so on) that make it possible to specify working directories
1299per operation.
1300
1301For portability, and because the clowns who "designed", or shall I write,
1302perpetrated this new interface were obviously half-drunk, this abstraction
1303cannot be perfect, though.
1304
1305IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1306object. This object stores the canonicalised, absolute version of the
1307path, and on systems that allow it, also a directory file descriptor.
1308
1309Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1310or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1311object and a pathname instead (or the IO::AIO::WD object alone, which
1312gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1313IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1314to that IO::AIO::WD object.
1315
1316For example, to get a wd object for F</etc> and then stat F<passwd>
1317inside, you would write:
1318
1319 aio_wd "/etc", sub {
1320 my $etcdir = shift;
1321
1322 # although $etcdir can be undef on error, there is generally no reason
1323 # to check for errors here, as aio_stat will fail with ENOENT
1324 # when $etcdir is undef.
1325
1326 aio_stat [$etcdir, "passwd"], sub {
1327 # yay
1328 };
1329 };
1330
1331That C<aio_wd> is a request and not a normal function shows that creating
1332an IO::AIO::WD object is itself a potentially blocking operation, which is
1333why it is done asynchronously.
1334
1335To stat the directory obtained with C<aio_wd> above, one could write
1336either of the following three request calls:
1337
1338 aio_lstat "/etc" , sub { ... # pathname as normal string
1339 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1340 aio_lstat $wd , sub { ... # shorthand for the previous
1341
1342As with normal pathnames, IO::AIO keeps a copy of the working directory
1343object and the pathname string, so you could write the following without
1344causing any issues due to C<$path> getting reused:
1345
1346 my $path = [$wd, undef];
1347
1348 for my $name (qw(abc def ghi)) {
1349 $path->[1] = $name;
1350 aio_stat $path, sub {
1351 # ...
1352 };
1353 }
1354
1355There are some caveats: when directories get renamed (or deleted), the
1356pathname string doesn't change, so will point to the new directory (or
1357nowhere at all), while the directory fd, if available on the system,
1358will still point to the original directory. Most functions accepting a
1359pathname will use the directory fd on newer systems, and the string on
1360older systems. Some functions (such as realpath) will always rely on the
1361string form of the pathname.
1362
1363So this fucntionality is mainly useful to get some protection against
1364C<chdir>, to easily get an absolute path out of a relative path for future
1365reference, and to speed up doing many operations in the same directory
1366(e.g. when stat'ing all files in a directory).
1367
1368The following functions implement this working directory abstraction:
1369
1370=over 4
1371
1372=item aio_wd $pathname, $callback->($wd)
1373
1374Asynchonously canonicalise the given pathname and convert it to an
1375IO::AIO::WD object representing it. If possible and supported on the
1376system, also open a directory fd to speed up pathname resolution relative
1377to this working directory.
1378
1379If something goes wrong, then C<undef> is passwd to the callback instead
1380of a working directory object and C<$!> is set appropriately. Since
1381passing C<undef> as working directory component of a pathname fails the
1382request with C<ENOENT>, there is often no need for error checking in the
1383C<aio_wd> callback, as future requests using the value will fail in the
1384expected way.
1385
1386If this call isn't available because your OS lacks it or it couldn't be
1387detected, it will be emulated by calling C<fsync> instead.
1388
1389=item IO::AIO::CWD
1390
1391This is a compiletime constant (object) that represents the process
1392current working directory.
1393
1394Specifying this object as working directory object for a pathname is as
1395if the pathname would be specified directly, without a directory object,
1396e.g., these calls are functionally identical:
1397
1398 aio_stat "somefile", sub { ... };
1399 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1400
1401=back
1402
1403
1202=head2 IO::AIO::REQ CLASS 1404=head2 IO::AIO::REQ CLASS
1203 1405
1204All non-aggregate C<aio_*> functions return an object of this class when 1406All non-aggregate C<aio_*> functions return an object of this class when
1205called in non-void context. 1407called in non-void context.
1206 1408
… …
1323 1525
1324Sets a feeder/generator on this group: every group can have an attached 1526Sets a feeder/generator on this group: every group can have an attached
1325generator that generates requests if idle. The idea behind this is that, 1527generator that generates requests if idle. The idea behind this is that,
1326although you could just queue as many requests as you want in a group, 1528although you could just queue as many requests as you want in a group,
1327this might starve other requests for a potentially long time. For example, 1529this might starve other requests for a potentially long time. For example,
1328C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, 1530C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1329delaying any later requests for a long time. 1531requests, delaying any later requests for a long time.
1330 1532
1331To avoid this, and allow incremental generation of requests, you can 1533To avoid this, and allow incremental generation of requests, you can
1332instead a group and set a feeder on it that generates those requests. The 1534instead a group and set a feeder on it that generates those requests. The
1333feed callback will be called whenever there are few enough (see C<limit>, 1535feed callback will be called whenever there are few enough (see C<limit>,
1334below) requests active in the group itself and is expected to queue more 1536below) requests active in the group itself and is expected to queue more
… …
1383 1585
1384See C<poll_cb> for an example. 1586See C<poll_cb> for an example.
1385 1587
1386=item IO::AIO::poll_cb 1588=item IO::AIO::poll_cb
1387 1589
1388Process some outstanding events on the result pipe. You have to call this 1590Process some outstanding events on the result pipe. You have to call
1389regularly. Returns C<0> if all events could be processed, or C<-1> if it 1591this regularly. Returns C<0> if all events could be processed (or there
1390returned earlier for whatever reason. Returns immediately when no events 1592were no events to process), or C<-1> if it returned earlier for whatever
1391are outstanding. The amount of events processed depends on the settings of 1593reason. Returns immediately when no events are outstanding. The amount of
1392C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1594events processed depends on the settings of C<IO::AIO::max_poll_req> and
1595C<IO::AIO::max_poll_time>.
1393 1596
1394If not all requests were processed for whatever reason, the filehandle 1597If not all requests were processed for whatever reason, the filehandle
1395will still be ready when C<poll_cb> returns, so normally you don't have to 1598will still be ready when C<poll_cb> returns, so normally you don't have to
1396do anything special to have it called later. 1599do anything special to have it called later.
1600
1601Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1602ready, it can be beneficial to call this function from loops which submit
1603a lot of requests, to make sure the results get processed when they become
1604available and not just when the loop is finished and the event loop takes
1605over again. This function returns very fast when there are no outstanding
1606requests.
1397 1607
1398Example: Install an Event watcher that automatically calls 1608Example: Install an Event watcher that automatically calls
1399IO::AIO::poll_cb with high priority (more examples can be found in the 1609IO::AIO::poll_cb with high priority (more examples can be found in the
1400SYNOPSIS section, at the top of this document): 1610SYNOPSIS section, at the top of this document):
1401 1611
… …
1503 1713
1504Under normal circumstances you don't need to call this function. 1714Under normal circumstances you don't need to call this function.
1505 1715
1506=item IO::AIO::max_idle $nthreads 1716=item IO::AIO::max_idle $nthreads
1507 1717
1508Limit the number of threads (default: 4) that are allowed to idle (i.e., 1718Limit the number of threads (default: 4) that are allowed to idle
1509threads that did not get a request to process within 10 seconds). That 1719(i.e., threads that did not get a request to process within the idle
1510means if a thread becomes idle while C<$nthreads> other threads are also 1720timeout (default: 10 seconds). That means if a thread becomes idle while
1511idle, it will free its resources and exit. 1721C<$nthreads> other threads are also idle, it will free its resources and
1722exit.
1512 1723
1513This is useful when you allow a large number of threads (e.g. 100 or 1000) 1724This is useful when you allow a large number of threads (e.g. 100 or 1000)
1514to allow for extremely high load situations, but want to free resources 1725to allow for extremely high load situations, but want to free resources
1515under normal circumstances (1000 threads can easily consume 30MB of RAM). 1726under normal circumstances (1000 threads can easily consume 30MB of RAM).
1516 1727
1517The default is probably ok in most situations, especially if thread 1728The default is probably ok in most situations, especially if thread
1518creation is fast. If thread creation is very slow on your system you might 1729creation is fast. If thread creation is very slow on your system you might
1519want to use larger values. 1730want to use larger values.
1520 1731
1732=item IO::AIO::idle_timeout $seconds
1733
1734Sets the minimum idle timeout (default 10) after which worker threads are
1735allowed to exit. SEe C<IO::AIO::max_idle>.
1736
1521=item IO::AIO::max_outstanding $maxreqs 1737=item IO::AIO::max_outstanding $maxreqs
1738
1739Sets the maximum number of outstanding requests to C<$nreqs>. If
1740you do queue up more than this number of requests, the next call to
1741C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1742C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1743longer exceeded.
1744
1745In other words, this setting does not enforce a queue limit, but can be
1746used to make poll functions block if the limit is exceeded.
1522 1747
1523This is a very bad function to use in interactive programs because it 1748This is a very bad function to use in interactive programs because it
1524blocks, and a bad way to reduce concurrency because it is inexact: Better 1749blocks, and a bad way to reduce concurrency because it is inexact: Better
1525use an C<aio_group> together with a feed callback. 1750use an C<aio_group> together with a feed callback.
1526 1751
1527Sets the maximum number of outstanding requests to C<$nreqs>. If you 1752It's main use is in scripts without an event loop - when you want to stat
1528do queue up more than this number of requests, the next call to the 1753a lot of files, you can write somehting like this:
1529C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1530function will block until the limit is no longer exceeded.
1531 1754
1532The default value is very large, so there is no practical limit on the 1755 IO::AIO::max_outstanding 32;
1533number of outstanding requests.
1534 1756
1535You can still queue as many requests as you want. Therefore, 1757 for my $path (...) {
1536C<max_outstanding> is mainly useful in simple scripts (with low values) or 1758 aio_stat $path , ...;
1537as a stop gap to shield against fatal memory overflow (with large values). 1759 IO::AIO::poll_cb;
1760 }
1761
1762 IO::AIO::flush;
1763
1764The call to C<poll_cb> inside the loop will normally return instantly, but
1765as soon as more thna C<32> reqeusts are in-flight, it will block until
1766some requests have been handled. This keeps the loop from pushing a large
1767number of C<aio_stat> requests onto the queue.
1768
1769The default value for C<max_outstanding> is very large, so there is no
1770practical limit on the number of outstanding requests.
1538 1771
1539=back 1772=back
1540 1773
1541=head3 STATISTICAL INFORMATION 1774=head3 STATISTICAL INFORMATION
1542 1775
… …
1580 1813
1581Returns the number of bytes copied, or C<-1> on error. 1814Returns the number of bytes copied, or C<-1> on error.
1582 1815
1583=item IO::AIO::fadvise $fh, $offset, $len, $advice 1816=item IO::AIO::fadvise $fh, $offset, $len, $advice
1584 1817
1585Simply calls the C<posix_fadvise> function (see it's 1818Simply calls the C<posix_fadvise> function (see its
1586manpage for details). The following advice constants are 1819manpage for details). The following advice constants are
1587avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>, 1820available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1588C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>, 1821C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1589C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>. 1822C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1590 1823
1591On systems that do not implement C<posix_fadvise>, this function returns 1824On systems that do not implement C<posix_fadvise>, this function returns
1592ENOSYS, otherwise the return value of C<posix_fadvise>. 1825ENOSYS, otherwise the return value of C<posix_fadvise>.
1826
1827=item IO::AIO::madvise $scalar, $offset, $len, $advice
1828
1829Simply calls the C<posix_madvise> function (see its
1830manpage for details). The following advice constants are
1831available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1832C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1833
1834On systems that do not implement C<posix_madvise>, this function returns
1835ENOSYS, otherwise the return value of C<posix_madvise>.
1836
1837=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1838
1839Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1840$scalar (see its manpage for details). The following protect
1841constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1842C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1843
1844On systems that do not implement C<mprotect>, this function returns
1845ENOSYS, otherwise the return value of C<mprotect>.
1593 1846
1594=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1847=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1595 1848
1596Memory-maps a file (or anonymous memory range) and attaches it to the 1849Memory-maps a file (or anonymous memory range) and attaches it to the
1597given C<$scalar>, which will act like a string scalar. 1850given C<$scalar>, which will act like a string scalar.
… …
1698 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 1951 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1699 \&IO::AIO::poll_cb); 1952 \&IO::AIO::poll_cb);
1700 1953
1701=head2 FORK BEHAVIOUR 1954=head2 FORK BEHAVIOUR
1702 1955
1703This module should do "the right thing" when the process using it forks: 1956Usage of pthreads in a program changes the semantics of fork
1957considerably. Specifically, only async-safe functions can be called after
1958fork. Perl doesn't know about this, so in general, you cannot call fork
1959with defined behaviour in perl if pthreads are involved. IO::AIO uses
1960pthreads, so this applies, but many other extensions and (for inexplicable
1961reasons) perl itself often is linked against pthreads, so this limitation
1962applies to quite a lot of perls.
1704 1963
1705Before the fork, IO::AIO enters a quiescent state where no requests 1964This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1706can be added in other threads and no results will be processed. After 1965only works in the process that loaded it. Forking is fully supported, but
1707the fork the parent simply leaves the quiescent state and continues 1966using IO::AIO in the child is not.
1708request/result processing, while the child frees the request/result queue
1709(so that the requests started before the fork will only be handled in the
1710parent). Threads will be started on demand until the limit set in the
1711parent process has been reached again.
1712 1967
1713In short: the parent will, after a short pause, continue as if fork had 1968You might get around by not I<using> IO::AIO before (or after)
1714not been called, while the child will act as if IO::AIO has not been used 1969forking. You could also try to call the L<IO::AIO::reinit> function in the
1715yet. 1970child:
1971
1972=over 4
1973
1974=item IO::AIO::reinit
1975
1976Abandons all current requests and I/O threads and simply reinitialises all
1977data structures. This is not an operation supported by any standards, but
1978happens to work on GNU/Linux and some newer BSD systems.
1979
1980The only reasonable use for this function is to call it after forking, if
1981C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
1982the process will result in undefined behaviour. Calling it at any time
1983will also result in any undefined (by POSIX) behaviour.
1984
1985=back
1716 1986
1717=head2 MEMORY USAGE 1987=head2 MEMORY USAGE
1718 1988
1719Per-request usage: 1989Per-request usage:
1720 1990

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