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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.267 by root, Tue Aug 9 11:39:17 2016 UTC vs.
Revision 1.279 by root, Sat Jan 6 01:04:42 2018 UTC

171use common::sense; 171use common::sense;
172 172
173use base 'Exporter'; 173use base 'Exporter';
174 174
175BEGIN { 175BEGIN {
176 our $VERSION = 4.34; 176 our $VERSION = 4.4;
177 177
178 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close 178 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
179 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx 179 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
180 aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl 180 aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
181 aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range 181 aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
182 aio_pathsync aio_readahead aio_fiemap aio_allocate 182 aio_pathsync aio_readahead aio_fiemap aio_allocate
183 aio_rename aio_link aio_move aio_copy aio_group 183 aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
184 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 184 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
185 aio_chmod aio_utime aio_truncate 185 aio_chmod aio_utime aio_truncate
186 aio_msync aio_mtouch aio_mlock aio_mlockall 186 aio_msync aio_mtouch aio_mlock aio_mlockall
187 aio_statvfs 187 aio_statvfs
188 aio_slurp
188 aio_wd); 189 aio_wd);
189 190
190 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 191 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
191 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 192 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
192 min_parallel max_parallel max_idle idle_timeout 193 min_parallel max_parallel max_idle idle_timeout
233 aio_link $srcpath, $dstpath, $callback->($status) 234 aio_link $srcpath, $dstpath, $callback->($status)
234 aio_symlink $srcpath, $dstpath, $callback->($status) 235 aio_symlink $srcpath, $dstpath, $callback->($status)
235 aio_readlink $pathname, $callback->($link) 236 aio_readlink $pathname, $callback->($link)
236 aio_realpath $pathname, $callback->($path) 237 aio_realpath $pathname, $callback->($path)
237 aio_rename $srcpath, $dstpath, $callback->($status) 238 aio_rename $srcpath, $dstpath, $callback->($status)
239 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
238 aio_mkdir $pathname, $mode, $callback->($status) 240 aio_mkdir $pathname, $mode, $callback->($status)
239 aio_rmdir $pathname, $callback->($status) 241 aio_rmdir $pathname, $callback->($status)
240 aio_readdir $pathname, $callback->($entries) 242 aio_readdir $pathname, $callback->($entries)
241 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 243 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
242 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 244 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
252 aio_syncfs $fh, $callback->($status) 254 aio_syncfs $fh, $callback->($status)
253 aio_fsync $fh, $callback->($status) 255 aio_fsync $fh, $callback->($status)
254 aio_fdatasync $fh, $callback->($status) 256 aio_fdatasync $fh, $callback->($status)
255 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 257 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
256 aio_pathsync $pathname, $callback->($status) 258 aio_pathsync $pathname, $callback->($status)
257 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 259 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
258 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 260 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
259 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 261 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
260 aio_mlockall $flags, $callback->($status) 262 aio_mlockall $flags, $callback->($status)
261 aio_group $callback->(...) 263 aio_group $callback->(...)
262 aio_nop $callback->() 264 aio_nop $callback->()
276 IO::AIO::idle_timeout $seconds 278 IO::AIO::idle_timeout $seconds
277 IO::AIO::max_outstanding $maxreqs 279 IO::AIO::max_outstanding $maxreqs
278 IO::AIO::nreqs 280 IO::AIO::nreqs
279 IO::AIO::nready 281 IO::AIO::nready
280 IO::AIO::npending 282 IO::AIO::npending
283 $nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
284 IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
281 285
282 IO::AIO::sendfile $ofh, $ifh, $offset, $count 286 IO::AIO::sendfile $ofh, $ifh, $offset, $count
283 IO::AIO::fadvise $fh, $offset, $len, $advice 287 IO::AIO::fadvise $fh, $offset, $len, $advice
284 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] 288 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
285 IO::AIO::munmap $scalar 289 IO::AIO::munmap $scalar
739C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate 743C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
740space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>, 744space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
741to deallocate a file range. 745to deallocate a file range.
742 746
743IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range 747IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
744(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see 748(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
745your L<fallocate(2)> manpage). 749C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
750to unshare shared blocks (see your L<fallocate(2)> manpage).
746 751
747The file system block size used by C<fallocate> is presumably the 752The file system block size used by C<fallocate> is presumably the
748C<f_bsize> returned by C<statvfs>. 753C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
754can dictate other limitations.
749 755
750If C<fallocate> isn't available or cannot be emulated (currently no 756If C<fallocate> isn't available or cannot be emulated (currently no
751emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>. 757emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
752 758
753 759
810rename(2) and call the callback with the result code. 816rename(2) and call the callback with the result code.
811 817
812On systems that support the AIO::WD working directory abstraction 818On systems that support the AIO::WD working directory abstraction
813natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead 819natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
814of failing, C<rename> is called on the absolute path of C<$wd>. 820of failing, C<rename> is called on the absolute path of C<$wd>.
821
822
823=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
824
825Basically a version of C<aio_rename> with an additional C<$flags>
826argument. Calling this with C<$flags=0> is the same as calling
827C<aio_rename>.
828
829Non-zero flags are currently only supported on GNU/Linux systems that
830support renameat2. Other systems fail with C<ENOSYS> in this case.
831
832The following constants are available (missing ones are, as usual C<0>),
833see renameat2(2) for details:
834
835C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
836and C<IO::AIO::RENAME_WHITEOUT>.
815 837
816 838
817=item aio_mkdir $pathname, $mode, $callback->($status) 839=item aio_mkdir $pathname, $mode, $callback->($status)
818 840
819Asynchronously mkdir (create) a directory and call the callback with 841Asynchronously mkdir (create) a directory and call the callback with
905C<$type>'s are known, which can be used to speed up some algorithms. 927C<$type>'s are known, which can be used to speed up some algorithms.
906 928
907=back 929=back
908 930
909 931
932=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
933
934Opens, reads and closes the given file. The data is put into C<$data>,
935which is resized as required.
936
937If C<$offset> is negative, then it is counted from the end of the file.
938
939If C<$length> is zero, then the remaining length of the file is
940used. Also, in this case, the same limitations to modifying C<$data> apply
941as when IO::AIO::mmap is used, i.e. it must only be modified in-place
942with C<substr>. If the size of the file is known, specifying a non-zero
943C<$length> results in a performance advantage.
944
945This request is similar to the older C<aio_load> request, but since it is
946a single request, it might be more efficient to use.
947
948Example: load F</etc/passwd> into C<$passwd>.
949
950 my $passwd;
951 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
952 $_[0] >= 0
953 or die "/etc/passwd: $!\n";
954
955 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
956 print $passwd;
957 };
958 IO::AIO::flush;
959
960
910=item aio_load $pathname, $data, $callback->($status) 961=item aio_load $pathname, $data, $callback->($status)
911 962
912This is a composite request that tries to fully load the given file into 963This is a composite request that tries to fully load the given file into
913memory. Status is the same as with aio_read. 964memory. Status is the same as with aio_read.
965
966Using C<aio_slurp> might be more efficient, as it is a single request.
914 967
915=cut 968=cut
916 969
917sub aio_load($$;$) { 970sub aio_load($$;$) {
918 my ($path, undef, $cb) = @_; 971 my ($path, undef, $cb) = @_;
938=item aio_copy $srcpath, $dstpath, $callback->($status) 991=item aio_copy $srcpath, $dstpath, $callback->($status)
939 992
940Try to copy the I<file> (directories not supported as either source or 993Try to copy the I<file> (directories not supported as either source or
941destination) from C<$srcpath> to C<$dstpath> and call the callback with 994destination) from C<$srcpath> to C<$dstpath> and call the callback with
942a status of C<0> (ok) or C<-1> (error, see C<$!>). 995a status of C<0> (ok) or C<-1> (error, see C<$!>).
996
997Existing destination files will be truncated.
943 998
944This is a composite request that creates the destination file with 999This is a composite request that creates the destination file with
945mode 0200 and copies the contents of the source file into it using 1000mode 0200 and copies the contents of the source file into it using
946C<aio_sendfile>, followed by restoring atime, mtime, access mode and 1001C<aio_sendfile>, followed by restoring atime, mtime, access mode and
947uid/gid, in that order. 1002uid/gid, in that order.
1057Scans a directory (similar to C<aio_readdir>) but additionally tries to 1112Scans a directory (similar to C<aio_readdir>) but additionally tries to
1058efficiently separate the entries of directory C<$path> into two sets of 1113efficiently separate the entries of directory C<$path> into two sets of
1059names, directories you can recurse into (directories), and ones you cannot 1114names, directories you can recurse into (directories), and ones you cannot
1060recurse into (everything else, including symlinks to directories). 1115recurse into (everything else, including symlinks to directories).
1061 1116
1062C<aio_scandir> is a composite request that creates of many sub requests_ 1117C<aio_scandir> is a composite request that generates many sub requests.
1063C<$maxreq> specifies the maximum number of outstanding aio requests that 1118C<$maxreq> specifies the maximum number of outstanding aio requests that
1064this function generates. If it is C<< <= 0 >>, then a suitable default 1119this function generates. If it is C<< <= 0 >>, then a suitable default
1065will be chosen (currently 4). 1120will be chosen (currently 4).
1066 1121
1067On error, the callback is called without arguments, otherwise it receives 1122On error, the callback is called without arguments, otherwise it receives
1254other processes), although if you are careful and know what you are doing, 1309other processes), although if you are careful and know what you are doing,
1255you still can. 1310you still can.
1256 1311
1257The following constants are available (missing ones are, as usual C<0>): 1312The following constants are available (missing ones are, as usual C<0>):
1258 1313
1314C<F_DUPFD_CLOEXEC>,
1315
1316C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
1317
1259C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>. 1318C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
1260 1319
1261C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>, 1320C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
1262C<FS_IOC_FIEMAP>. 1321C<FS_IOC_FIEMAP>.
1263 1322
1350 }; 1409 };
1351 1410
1352 $grp 1411 $grp
1353} 1412}
1354 1413
1355=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1414=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1356 1415
1357This is a rather advanced IO::AIO call, which only works on mmap(2)ed 1416This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1358scalars (see the C<IO::AIO::mmap> function, although it also works on data 1417scalars (see the C<IO::AIO::mmap> function, although it also works on data
1359scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the 1418scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1360scalar must only be modified in-place while an aio operation is pending on 1419scalar must only be modified in-place while an aio operation is pending on
1362 1421
1363It calls the C<msync> function of your OS, if available, with the memory 1422It calls the C<msync> function of your OS, if available, with the memory
1364area starting at C<$offset> in the string and ending C<$length> bytes 1423area starting at C<$offset> in the string and ending C<$length> bytes
1365later. If C<$length> is negative, counts from the end, and if C<$length> 1424later. If C<$length> is negative, counts from the end, and if C<$length>
1366is C<undef>, then it goes till the end of the string. The flags can be 1425is C<undef>, then it goes till the end of the string. The flags can be
1367a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and 1426either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1368C<IO::AIO::MS_SYNC>. 1427C<IO::AIO::MS_INVALIDATE>.
1369 1428
1370=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1429=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1371 1430
1372This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1431This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1373scalars. 1432scalars.
1456C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>, 1515C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1457C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>, 1516C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1458C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or 1517C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1459C<IO::AIO::FIEMAP_EXTENT_SHARED>. 1518C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1460 1519
1461At the time of this writing (Linux 3.2), this requets is unreliable unless 1520At the time of this writing (Linux 3.2), this request is unreliable unless
1462C<$count> is C<undef>, as the kernel has all sorts of bugs preventing 1521C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1463it to return all extents of a range for files with large number of 1522it to return all extents of a range for files with a large number of
1464extents. The code works around all these issues if C<$count> is undef. 1523extents. The code (only) works around all these issues if C<$count> is
1524C<undef>.
1465 1525
1466=item aio_group $callback->(...) 1526=item aio_group $callback->(...)
1467 1527
1468This is a very special aio request: Instead of doing something, it is a 1528This is a very special aio request: Instead of doing something, it is a
1469container for other aio requests, which is useful if you want to bundle 1529container for other aio requests, which is useful if you want to bundle
1582There are some caveats: when directories get renamed (or deleted), the 1642There are some caveats: when directories get renamed (or deleted), the
1583pathname string doesn't change, so will point to the new directory (or 1643pathname string doesn't change, so will point to the new directory (or
1584nowhere at all), while the directory fd, if available on the system, 1644nowhere at all), while the directory fd, if available on the system,
1585will still point to the original directory. Most functions accepting a 1645will still point to the original directory. Most functions accepting a
1586pathname will use the directory fd on newer systems, and the string on 1646pathname will use the directory fd on newer systems, and the string on
1587older systems. Some functions (such as realpath) will always rely on the 1647older systems. Some functions (such as C<aio_realpath>) will always rely on
1588string form of the pathname. 1648the string form of the pathname.
1589 1649
1590So this functionality is mainly useful to get some protection against 1650So this functionality is mainly useful to get some protection against
1591C<chdir>, to easily get an absolute path out of a relative path for future 1651C<chdir>, to easily get an absolute path out of a relative path for future
1592reference, and to speed up doing many operations in the same directory 1652reference, and to speed up doing many operations in the same directory
1593(e.g. when stat'ing all files in a directory). 1653(e.g. when stat'ing all files in a directory).
1985This is a very bad function to use in interactive programs because it 2045This is a very bad function to use in interactive programs because it
1986blocks, and a bad way to reduce concurrency because it is inexact: Better 2046blocks, and a bad way to reduce concurrency because it is inexact: Better
1987use an C<aio_group> together with a feed callback. 2047use an C<aio_group> together with a feed callback.
1988 2048
1989Its main use is in scripts without an event loop - when you want to stat 2049Its main use is in scripts without an event loop - when you want to stat
1990a lot of files, you can write somehting like this: 2050a lot of files, you can write something like this:
1991 2051
1992 IO::AIO::max_outstanding 32; 2052 IO::AIO::max_outstanding 32;
1993 2053
1994 for my $path (...) { 2054 for my $path (...) {
1995 aio_stat $path , ...; 2055 aio_stat $path , ...;
2040some "Advanced I/O" function not available to in Perl, without going the 2100some "Advanced I/O" function not available to in Perl, without going the
2041"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*> 2101"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
2042counterpart. 2102counterpart.
2043 2103
2044=over 4 2104=over 4
2105
2106=item $numfd = IO::AIO::get_fdlimit
2107
2108This function is I<EXPERIMENTAL> and subject to change.
2109
2110Tries to find the current file descriptor limit and returns it, or
2111C<undef> and sets C<$!> in case of an error. The limit is one larger than
2112the highest valid file descriptor number.
2113
2114=item IO::AIO::min_fdlimit [$numfd]
2115
2116This function is I<EXPERIMENTAL> and subject to change.
2117
2118Try to increase the current file descriptor limit(s) to at least C<$numfd>
2119by changing the soft or hard file descriptor resource limit. If C<$numfd>
2120is missing, it will try to set a very high limit, although this is not
2121recommended when you know the actual minimum that you require.
2122
2123If the limit cannot be raised enough, the function makes a best-effort
2124attempt to increase the limit as much as possible, using various
2125tricks, while still failing. You can query the resulting limit using
2126C<IO::AIO::get_fdlimit>.
2127
2128If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
2129true.
2045 2130
2046=item IO::AIO::sendfile $ofh, $ifh, $offset, $count 2131=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
2047 2132
2048Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>, 2133Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
2049but is blocking (this makes most sense if you know the input data is 2134but is blocking (this makes most sense if you know the input data is
2066=item IO::AIO::madvise $scalar, $offset, $len, $advice 2151=item IO::AIO::madvise $scalar, $offset, $len, $advice
2067 2152
2068Simply calls the C<posix_madvise> function (see its 2153Simply calls the C<posix_madvise> function (see its
2069manpage for details). The following advice constants are 2154manpage for details). The following advice constants are
2070available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, 2155available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
2071C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>, 2156C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
2072C<IO::AIO::MADV_FREE>. 2157C<IO::AIO::MADV_DONTNEED>.
2158
2159If C<$offset> is negative, counts from the end. If C<$length> is negative,
2160the remaining length of the C<$scalar> is used. If possible, C<$length>
2161will be reduced to fit into the C<$scalar>.
2073 2162
2074On systems that do not implement C<posix_madvise>, this function returns 2163On systems that do not implement C<posix_madvise>, this function returns
2075ENOSYS, otherwise the return value of C<posix_madvise>. 2164ENOSYS, otherwise the return value of C<posix_madvise>.
2076 2165
2077=item IO::AIO::mprotect $scalar, $offset, $len, $protect 2166=item IO::AIO::mprotect $scalar, $offset, $len, $protect
2079Simply calls the C<mprotect> function on the preferably AIO::mmap'ed 2168Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
2080$scalar (see its manpage for details). The following protect 2169$scalar (see its manpage for details). The following protect
2081constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, 2170constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
2082C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. 2171C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
2083 2172
2173If C<$offset> is negative, counts from the end. If C<$length> is negative,
2174the remaining length of the C<$scalar> is used. If possible, C<$length>
2175will be reduced to fit into the C<$scalar>.
2176
2084On systems that do not implement C<mprotect>, this function returns 2177On systems that do not implement C<mprotect>, this function returns
2085ENOSYS, otherwise the return value of C<mprotect>. 2178ENOSYS, otherwise the return value of C<mprotect>.
2086 2179
2087=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 2180=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
2088 2181
2089Memory-maps a file (or anonymous memory range) and attaches it to the 2182Memory-maps a file (or anonymous memory range) and attaches it to the
2090given C<$scalar>, which will act like a string scalar. Returns true on 2183given C<$scalar>, which will act like a string scalar. Returns true on
2091success, and false otherwise. 2184success, and false otherwise.
2092 2185
2186The scalar must exist, but its contents do not matter - this means you
2187cannot use a nonexistant array or hash element. When in doubt, C<undef>
2188the scalar first.
2189
2093The only operations allowed on the scalar are C<substr>/C<vec> that don't 2190The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
2094change the string length, and most read-only operations such as copying it 2191which don't change the string length, and most read-only operations such
2095or searching it with regexes and so on. 2192as copying it or searching it with regexes and so on.
2096 2193
2097Anything else is unsafe and will, at best, result in memory leaks. 2194Anything else is unsafe and will, at best, result in memory leaks.
2098 2195
2099The memory map associated with the C<$scalar> is automatically removed 2196The memory map associated with the C<$scalar> is automatically removed
2100when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or 2197when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
2101C<IO::AIO::munmap> functions are called. 2198or C<IO::AIO::munmap> functions are called on it.
2102 2199
2103This calls the C<mmap>(2) function internally. See your system's manual 2200This calls the C<mmap>(2) function internally. See your system's manual
2104page for details on the C<$length>, C<$prot> and C<$flags> parameters. 2201page for details on the C<$length>, C<$prot> and C<$flags> parameters.
2105 2202
2106The C<$length> must be larger than zero and smaller than the actual 2203The C<$length> must be larger than zero and smaller than the actual

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