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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.241 by root, Fri Dec 28 07:33:41 2012 UTC vs.
Revision 1.270 by root, Fri Jun 23 03:23:19 2017 UTC

1=head1 NAME 1=head1 NAME
2 2
3IO::AIO - Asynchronous Input/Output 3IO::AIO - Asynchronous/Advanced Input/Output
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
58not well-supported or restricted (GNU/Linux doesn't allow them on normal 58not well-supported or restricted (GNU/Linux doesn't allow them on normal
59files currently, for example), and they would only support aio_read and 59files currently, for example), and they would only support aio_read and
60aio_write, so the remaining functionality would have to be implemented 60aio_write, so the remaining functionality would have to be implemented
61using threads anyway. 61using threads anyway.
62 62
63In addition to asynchronous I/O, this module also exports some rather
64arcane interfaces, such as C<madvise> or linux's C<splice> system call,
65which is why the C<A> in C<AIO> can also mean I<advanced>.
66
63Although the module will work in the presence of other (Perl-) threads, 67Although the module will work in the presence of other (Perl-) threads,
64it is currently not reentrant in any way, so use appropriate locking 68it is currently not reentrant in any way, so use appropriate locking
65yourself, always call C<poll_cb> from within the same thread, or never 69yourself, always call C<poll_cb> from within the same thread, or never
66call C<poll_cb> (or other C<aio_> functions) recursively. 70call C<poll_cb> (or other C<aio_> functions) recursively.
67 71
68=head2 EXAMPLE 72=head2 EXAMPLE
69 73
70This is a simple example that uses the EV module and loads 74This is a simple example that uses the EV module and loads
71F</etc/passwd> asynchronously: 75F</etc/passwd> asynchronously:
72 76
73 use Fcntl;
74 use EV; 77 use EV;
75 use IO::AIO; 78 use IO::AIO;
76 79
77 # register the IO::AIO callback with EV 80 # register the IO::AIO callback with EV
78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 81 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
95 98
96 # file contents now in $contents 99 # file contents now in $contents
97 print $contents; 100 print $contents;
98 101
99 # exit event loop and program 102 # exit event loop and program
100 EV::unloop; 103 EV::break;
101 }; 104 };
102 }; 105 };
103 106
104 # possibly queue up other requests, or open GUI windows, 107 # possibly queue up other requests, or open GUI windows,
105 # check for sockets etc. etc. 108 # check for sockets etc. etc.
106 109
107 # process events as long as there are some: 110 # process events as long as there are some:
108 EV::loop; 111 EV::run;
109 112
110=head1 REQUEST ANATOMY AND LIFETIME 113=head1 REQUEST ANATOMY AND LIFETIME
111 114
112Every C<aio_*> function creates a request. which is a C data structure not 115Every C<aio_*> function creates a request. which is a C data structure not
113directly visible to Perl. 116directly visible to Perl.
168use common::sense; 171use common::sense;
169 172
170use base 'Exporter'; 173use base 'Exporter';
171 174
172BEGIN { 175BEGIN {
173 our $VERSION = '4.18'; 176 our $VERSION = 4.35;
174 177
175 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
176 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
177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync 180 aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_allocate 181 aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179 aio_pathsync aio_readahead aio_fiemap 182 aio_pathsync aio_readahead aio_fiemap aio_allocate
180 aio_rename aio_link aio_move aio_copy aio_group 183 aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181 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
182 aio_chmod aio_utime aio_truncate 185 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall 186 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs 187 aio_statvfs
185 aio_wd); 188 aio_wd);
228 aio_unlink $pathname, $callback->($status) 231 aio_unlink $pathname, $callback->($status)
229 aio_mknod $pathname, $mode, $dev, $callback->($status) 232 aio_mknod $pathname, $mode, $dev, $callback->($status)
230 aio_link $srcpath, $dstpath, $callback->($status) 233 aio_link $srcpath, $dstpath, $callback->($status)
231 aio_symlink $srcpath, $dstpath, $callback->($status) 234 aio_symlink $srcpath, $dstpath, $callback->($status)
232 aio_readlink $pathname, $callback->($link) 235 aio_readlink $pathname, $callback->($link)
233 aio_realpath $pathname, $callback->($link) 236 aio_realpath $pathname, $callback->($path)
234 aio_rename $srcpath, $dstpath, $callback->($status) 237 aio_rename $srcpath, $dstpath, $callback->($status)
238 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
235 aio_mkdir $pathname, $mode, $callback->($status) 239 aio_mkdir $pathname, $mode, $callback->($status)
236 aio_rmdir $pathname, $callback->($status) 240 aio_rmdir $pathname, $callback->($status)
237 aio_readdir $pathname, $callback->($entries) 241 aio_readdir $pathname, $callback->($entries)
238 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 242 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
239 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 243 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
241 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 245 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242 aio_load $pathname, $data, $callback->($status) 246 aio_load $pathname, $data, $callback->($status)
243 aio_copy $srcpath, $dstpath, $callback->($status) 247 aio_copy $srcpath, $dstpath, $callback->($status)
244 aio_move $srcpath, $dstpath, $callback->($status) 248 aio_move $srcpath, $dstpath, $callback->($status)
245 aio_rmtree $pathname, $callback->($status) 249 aio_rmtree $pathname, $callback->($status)
250 aio_fcntl $fh, $cmd, $arg, $callback->($status)
251 aio_ioctl $fh, $request, $buf, $callback->($status)
246 aio_sync $callback->($status) 252 aio_sync $callback->($status)
247 aio_syncfs $fh, $callback->($status) 253 aio_syncfs $fh, $callback->($status)
248 aio_fsync $fh, $callback->($status) 254 aio_fsync $fh, $callback->($status)
249 aio_fdatasync $fh, $callback->($status) 255 aio_fdatasync $fh, $callback->($status)
250 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 256 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
251 aio_pathsync $pathname, $callback->($status) 257 aio_pathsync $pathname, $callback->($status)
252 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 258 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
253 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 259 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
254 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 260 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
255 aio_mlockall $flags, $callback->($status) 261 aio_mlockall $flags, $callback->($status)
256 aio_group $callback->(...) 262 aio_group $callback->(...)
257 aio_nop $callback->() 263 aio_nop $callback->()
395following POSIX and non-POSIX constants are available (missing ones on 401following POSIX and non-POSIX constants are available (missing ones on
396your system are, as usual, C<0>): 402your system are, as usual, C<0>):
397 403
398C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>, 404C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
399C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>, 405C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
400C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>. 406C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
401 407
402 408
403=item aio_close $fh, $callback->($status) 409=item aio_close $fh, $callback->($status)
404 410
405Asynchronously close a file and call the callback with the result 411Asynchronously close a file and call the callback with the result
440=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 446=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
441 447
442=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 448=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
443 449
444Reads or writes C<$length> bytes from or to the specified C<$fh> and 450Reads or writes C<$length> bytes from or to the specified C<$fh> and
445C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> 451C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
446and calls the callback without the actual number of bytes read (or -1 on 452calls the callback with the actual number of bytes transferred (or -1 on
447error, just like the syscall). 453error, just like the syscall).
448 454
449C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to 455C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
450offset plus the actual number of bytes read. 456offset plus the actual number of bytes read.
451 457
509As native sendfile syscalls (as practically any non-POSIX interface hacked 515As native sendfile syscalls (as practically any non-POSIX interface hacked
510together in a hurry to improve benchmark numbers) tend to be rather buggy 516together in a hurry to improve benchmark numbers) tend to be rather buggy
511on many systems, this implementation tries to work around some known bugs 517on many systems, this implementation tries to work around some known bugs
512in Linux and FreeBSD kernels (probably others, too), but that might fail, 518in Linux and FreeBSD kernels (probably others, too), but that might fail,
513so you really really should check the return value of C<aio_sendfile> - 519so you really really should check the return value of C<aio_sendfile> -
514fewre bytes than expected might have been transferred. 520fewer bytes than expected might have been transferred.
515 521
516 522
517=item aio_readahead $fh,$offset,$length, $callback->($retval) 523=item aio_readahead $fh,$offset,$length, $callback->($retval)
518 524
519C<aio_readahead> populates the page cache with data from a file so that 525C<aio_readahead> populates the page cache with data from a file so that
523whole pages, so that offset is effectively rounded down to a page boundary 529whole pages, so that offset is effectively rounded down to a page boundary
524and bytes are read up to the next page boundary greater than or equal to 530and bytes are read up to the next page boundary greater than or equal to
525(off-set+length). C<aio_readahead> does not read beyond the end of the 531(off-set+length). C<aio_readahead> does not read beyond the end of the
526file. The current file offset of the file is left unchanged. 532file. The current file offset of the file is left unchanged.
527 533
528If that syscall doesn't exist (likely if your OS isn't Linux) it will be 534If that syscall doesn't exist (likely if your kernel isn't Linux) it will
529emulated by simply reading the data, which would have a similar effect. 535be emulated by simply reading the data, which would have a similar effect.
530 536
531 537
532=item aio_stat $fh_or_path, $callback->($status) 538=item aio_stat $fh_or_path, $callback->($status)
533 539
534=item aio_lstat $fh, $callback->($status) 540=item aio_lstat $fh, $callback->($status)
603 namemax => 255, 609 namemax => 255,
604 frsize => 1024, 610 frsize => 1024,
605 fsid => 1810 611 fsid => 1810
606 } 612 }
607 613
608Here is a (likely partial) list of fsid values used by Linux - it is safe 614Here is a (likely partial - send me updates!) list of fsid values used by
609to hardcode these when the $^O is C<linux>: 615Linux - it is safe to hardcode these when C<$^O> is C<linux>:
610 616
611 0x0000adf5 adfs 617 0x0000adf5 adfs
612 0x0000adff affs 618 0x0000adff affs
613 0x5346414f afs 619 0x5346414f afs
614 0x09041934 anon-inode filesystem 620 0x09041934 anon-inode filesystem
627 0x00001373 devfs 633 0x00001373 devfs
628 0x00001cd1 devpts 634 0x00001cd1 devpts
629 0x0000f15f ecryptfs 635 0x0000f15f ecryptfs
630 0x00414a53 efs 636 0x00414a53 efs
631 0x0000137d ext 637 0x0000137d ext
632 0x0000ef53 ext2/ext3 638 0x0000ef53 ext2/ext3/ext4
633 0x0000ef51 ext2 639 0x0000ef51 ext2
640 0xf2f52010 f2fs
634 0x00004006 fat 641 0x00004006 fat
635 0x65735546 fuseblk 642 0x65735546 fuseblk
636 0x65735543 fusectl 643 0x65735543 fusectl
637 0x0bad1dea futexfs 644 0x0bad1dea futexfs
638 0x01161970 gfs2 645 0x01161970 gfs2
639 0x47504653 gpfs 646 0x47504653 gpfs
640 0x00004244 hfs 647 0x00004244 hfs
641 0xf995e849 hpfs 648 0xf995e849 hpfs
649 0x00c0ffee hostfs
642 0x958458f6 hugetlbfs 650 0x958458f6 hugetlbfs
643 0x2bad1dea inotifyfs 651 0x2bad1dea inotifyfs
644 0x00009660 isofs 652 0x00009660 isofs
645 0x000072b6 jffs2 653 0x000072b6 jffs2
646 0x3153464a jfs 654 0x3153464a jfs
661 0x00009fa1 openprom 669 0x00009fa1 openprom
662 0x7461636F ocfs2 670 0x7461636F ocfs2
663 0x00009fa0 proc 671 0x00009fa0 proc
664 0x6165676c pstorefs 672 0x6165676c pstorefs
665 0x0000002f qnx4 673 0x0000002f qnx4
674 0x68191122 qnx6
666 0x858458f6 ramfs 675 0x858458f6 ramfs
667 0x52654973 reiserfs 676 0x52654973 reiserfs
668 0x00007275 romfs 677 0x00007275 romfs
669 0x67596969 rpc_pipefs 678 0x67596969 rpc_pipefs
670 0x73636673 securityfs 679 0x73636673 securityfs
723Works like truncate(2) or ftruncate(2). 732Works like truncate(2) or ftruncate(2).
724 733
725 734
726=item aio_allocate $fh, $mode, $offset, $len, $callback->($status) 735=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
727 736
728Allocates or freed disk space according to the C<$mode> argument. See the 737Allocates or frees disk space according to the C<$mode> argument. See the
729linux C<fallocate> docuemntation for details. 738linux C<fallocate> documentation for details.
730 739
731C<$mode> can currently be C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> 740C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
732to allocate space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | 741space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
733IO::AIO::FALLOC_FL_KEEP_SIZE>, to deallocate a file range. 742to deallocate a file range.
743
744IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
745(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
746your L<fallocate(2)> manpage).
734 747
735The file system block size used by C<fallocate> is presumably the 748The file system block size used by C<fallocate> is presumably the
736C<f_bsize> returned by C<statvfs>. 749C<f_bsize> returned by C<statvfs>.
737 750
738If C<fallocate> isn't available or cannot be emulated (currently no 751If C<fallocate> isn't available or cannot be emulated (currently no
798rename(2) and call the callback with the result code. 811rename(2) and call the callback with the result code.
799 812
800On systems that support the AIO::WD working directory abstraction 813On systems that support the AIO::WD working directory abstraction
801natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead 814natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
802of failing, C<rename> is called on the absolute path of C<$wd>. 815of failing, C<rename> is called on the absolute path of C<$wd>.
816
817
818=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
819
820Basically a version of C<aio_rename> with an additional C<$flags>
821argument. Calling this with C<$flags=0> is the same as calling
822C<aio_rename>.
823
824Non-zero flags are currently only supported on GNU/Linux systems that
825support renameat2. Other systems fail with C<ENOSYS> in this case.
826
827The following constants are available (missing ones are, as usual C<0>),
828see renameat2(2) for details:
829
830C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
831and C<IO::AIO::RENAME_WHITEOUT>.
803 832
804 833
805=item aio_mkdir $pathname, $mode, $callback->($status) 834=item aio_mkdir $pathname, $mode, $callback->($status)
806 835
807Asynchronously mkdir (create) a directory and call the callback with 836Asynchronously mkdir (create) a directory and call the callback with
1221 }; 1250 };
1222 1251
1223 $grp 1252 $grp
1224} 1253}
1225 1254
1255=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
1256
1257=item aio_ioctl $fh, $request, $buf, $callback->($status)
1258
1259These work just like the C<fcntl> and C<ioctl> built-in functions, except
1260they execute asynchronously and pass the return value to the callback.
1261
1262Both calls can be used for a lot of things, some of which make more sense
1263to run asynchronously in their own thread, while some others make less
1264sense. For example, calls that block waiting for external events, such
1265as locking, will also lock down an I/O thread while it is waiting, which
1266can deadlock the whole I/O system. At the same time, there might be no
1267alternative to using a thread to wait.
1268
1269So in general, you should only use these calls for things that do
1270(filesystem) I/O, not for things that wait for other events (network,
1271other processes), although if you are careful and know what you are doing,
1272you still can.
1273
1274The following constants are available (missing ones are, as usual C<0>):
1275
1276C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
1277
1278C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
1279C<FS_IOC_FIEMAP>.
1280
1281C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
1282C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
1283
1284C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
1285C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
1286C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
1287C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
1288C<FS_FL_USER_MODIFIABLE>.
1289
1290C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
1291C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
1292C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
1293C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1294
1226=item aio_sync $callback->($status) 1295=item aio_sync $callback->($status)
1227 1296
1228Asynchronously call sync and call the callback when finished. 1297Asynchronously call sync and call the callback when finished.
1229 1298
1230=item aio_fsync $fh, $callback->($status) 1299=item aio_fsync $fh, $callback->($status)
1298 }; 1367 };
1299 1368
1300 $grp 1369 $grp
1301} 1370}
1302 1371
1303=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1372=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1304 1373
1305This is a rather advanced IO::AIO call, which only works on mmap(2)ed 1374This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1306scalars (see the C<IO::AIO::mmap> function, although it also works on data 1375scalars (see the C<IO::AIO::mmap> function, although it also works on data
1307scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the 1376scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1308scalar must only be modified in-place while an aio operation is pending on 1377scalar must only be modified in-place while an aio operation is pending on
1310 1379
1311It calls the C<msync> function of your OS, if available, with the memory 1380It calls the C<msync> function of your OS, if available, with the memory
1312area starting at C<$offset> in the string and ending C<$length> bytes 1381area starting at C<$offset> in the string and ending C<$length> bytes
1313later. If C<$length> is negative, counts from the end, and if C<$length> 1382later. If C<$length> is negative, counts from the end, and if C<$length>
1314is C<undef>, then it goes till the end of the string. The flags can be 1383is C<undef>, then it goes till the end of the string. The flags can be
1315a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and 1384either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1316C<IO::AIO::MS_SYNC>. 1385C<IO::AIO::MS_INVALIDATE>.
1317 1386
1318=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1387=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1319 1388
1320This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1389This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1321scalars. 1390scalars.
1501 aio_stat [$etcdir, "passwd"], sub { 1570 aio_stat [$etcdir, "passwd"], sub {
1502 # yay 1571 # yay
1503 }; 1572 };
1504 }; 1573 };
1505 1574
1506That C<aio_wd> is a request and not a normal function shows that creating 1575The fact that C<aio_wd> is a request and not a normal function shows that
1507an IO::AIO::WD object is itself a potentially blocking operation, which is 1576creating an IO::AIO::WD object is itself a potentially blocking operation,
1508why it is done asynchronously. 1577which is why it is done asynchronously.
1509 1578
1510To stat the directory obtained with C<aio_wd> above, one could write 1579To stat the directory obtained with C<aio_wd> above, one could write
1511either of the following three request calls: 1580either of the following three request calls:
1512 1581
1513 aio_lstat "/etc" , sub { ... # pathname as normal string 1582 aio_lstat "/etc" , sub { ... # pathname as normal string
1556passing C<undef> as working directory component of a pathname fails the 1625passing C<undef> as working directory component of a pathname fails the
1557request with C<ENOENT>, there is often no need for error checking in the 1626request with C<ENOENT>, there is often no need for error checking in the
1558C<aio_wd> callback, as future requests using the value will fail in the 1627C<aio_wd> callback, as future requests using the value will fail in the
1559expected way. 1628expected way.
1560 1629
1561If this call isn't available because your OS lacks it or it couldn't be
1562detected, it will be emulated by calling C<fsync> instead.
1563
1564=item IO::AIO::CWD 1630=item IO::AIO::CWD
1565 1631
1566This is a compiletime constant (object) that represents the process 1632This is a compiletime constant (object) that represents the process
1567current working directory. 1633current working directory.
1568 1634
1935 2001
1936This is a very bad function to use in interactive programs because it 2002This is a very bad function to use in interactive programs because it
1937blocks, and a bad way to reduce concurrency because it is inexact: Better 2003blocks, and a bad way to reduce concurrency because it is inexact: Better
1938use an C<aio_group> together with a feed callback. 2004use an C<aio_group> together with a feed callback.
1939 2005
1940It's main use is in scripts without an event loop - when you want to stat 2006Its main use is in scripts without an event loop - when you want to stat
1941a lot of files, you can write somehting like this: 2007a lot of files, you can write somehting like this:
1942 2008
1943 IO::AIO::max_outstanding 32; 2009 IO::AIO::max_outstanding 32;
1944 2010
1945 for my $path (...) { 2011 for my $path (...) {
1985 2051
1986=back 2052=back
1987 2053
1988=head3 MISCELLANEOUS FUNCTIONS 2054=head3 MISCELLANEOUS FUNCTIONS
1989 2055
1990IO::AIO implements some functions that might be useful, but are not 2056IO::AIO implements some functions that are useful when you want to use
1991asynchronous. 2057some "Advanced I/O" function not available to in Perl, without going the
2058"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
2059counterpart.
1992 2060
1993=over 4 2061=over 4
1994 2062
1995=item IO::AIO::sendfile $ofh, $ifh, $offset, $count 2063=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1996 2064
2015=item IO::AIO::madvise $scalar, $offset, $len, $advice 2083=item IO::AIO::madvise $scalar, $offset, $len, $advice
2016 2084
2017Simply calls the C<posix_madvise> function (see its 2085Simply calls the C<posix_madvise> function (see its
2018manpage for details). The following advice constants are 2086manpage for details). The following advice constants are
2019available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, 2087available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
2020C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>. 2088C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
2089C<IO::AIO::MADV_FREE>.
2090
2091If C<$offset> is negative, counts from the end. If C<$length> is negative,
2092the remaining length of the C<$scalar> is used. If possible, C<$length>
2093will be reduced to fit into the C<$scalar>.
2021 2094
2022On systems that do not implement C<posix_madvise>, this function returns 2095On systems that do not implement C<posix_madvise>, this function returns
2023ENOSYS, otherwise the return value of C<posix_madvise>. 2096ENOSYS, otherwise the return value of C<posix_madvise>.
2024 2097
2025=item IO::AIO::mprotect $scalar, $offset, $len, $protect 2098=item IO::AIO::mprotect $scalar, $offset, $len, $protect
2027Simply calls the C<mprotect> function on the preferably AIO::mmap'ed 2100Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
2028$scalar (see its manpage for details). The following protect 2101$scalar (see its manpage for details). The following protect
2029constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, 2102constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
2030C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. 2103C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
2031 2104
2105If C<$offset> is negative, counts from the end. If C<$length> is negative,
2106the remaining length of the C<$scalar> is used. If possible, C<$length>
2107will be reduced to fit into the C<$scalar>.
2108
2032On systems that do not implement C<mprotect>, this function returns 2109On systems that do not implement C<mprotect>, this function returns
2033ENOSYS, otherwise the return value of C<mprotect>. 2110ENOSYS, otherwise the return value of C<mprotect>.
2034 2111
2035=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 2112=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
2036 2113
2037Memory-maps a file (or anonymous memory range) and attaches it to the 2114Memory-maps a file (or anonymous memory range) and attaches it to the
2038given C<$scalar>, which will act like a string scalar. Returns true on 2115given C<$scalar>, which will act like a string scalar. Returns true on
2039success, and false otherwise. 2116success, and false otherwise.
2040 2117
2118The scalar must exist, but its contents do not matter - this means you
2119cannot use a nonexistant array or hash element. When in doubt, C<undef>
2120the scalar first.
2121
2041The only operations allowed on the scalar are C<substr>/C<vec> that don't 2122The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
2042change the string length, and most read-only operations such as copying it 2123which don't change the string length, and most read-only operations such
2043or searching it with regexes and so on. 2124as copying it or searching it with regexes and so on.
2044 2125
2045Anything else is unsafe and will, at best, result in memory leaks. 2126Anything else is unsafe and will, at best, result in memory leaks.
2046 2127
2047The memory map associated with the C<$scalar> is automatically removed 2128The memory map associated with the C<$scalar> is automatically removed
2048when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or 2129when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
2049C<IO::AIO::munmap> functions are called. 2130or C<IO::AIO::munmap> functions are called on it.
2050 2131
2051This calls the C<mmap>(2) function internally. See your system's manual 2132This calls the C<mmap>(2) function internally. See your system's manual
2052page for details on the C<$length>, C<$prot> and C<$flags> parameters. 2133page for details on the C<$length>, C<$prot> and C<$flags> parameters.
2053 2134
2054The C<$length> must be larger than zero and smaller than the actual 2135The C<$length> must be larger than zero and smaller than the actual
2055filesize. 2136filesize.
2056 2137
2057C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, 2138C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
2058C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, 2139C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
2059 2140
2060C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or 2141C<$flags> can be a combination of
2061C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when 2142C<IO::AIO::MAP_SHARED> or
2062not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS> 2143C<IO::AIO::MAP_PRIVATE>,
2144or a number of system-specific flags (when not available, the are C<0>):
2063(which is set to C<MAP_ANON> if your system only provides this 2145C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
2064constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>, 2146C<IO::AIO::MAP_LOCKED>,
2065C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or 2147C<IO::AIO::MAP_NORESERVE>,
2148C<IO::AIO::MAP_POPULATE>,
2066C<IO::AIO::MAP_NONBLOCK> 2149C<IO::AIO::MAP_NONBLOCK>,
2150C<IO::AIO::MAP_FIXED>,
2151C<IO::AIO::MAP_GROWSDOWN>,
2152C<IO::AIO::MAP_32BIT>,
2153C<IO::AIO::MAP_HUGETLB> or
2154C<IO::AIO::MAP_STACK>.
2067 2155
2068If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. 2156If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
2069 2157
2070C<$offset> is the offset from the start of the file - it generally must be 2158C<$offset> is the offset from the start of the file - it generally must be
2071a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. 2159a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
2114 2202
2115See the C<splice(2)> manpage for details. 2203See the C<splice(2)> manpage for details.
2116 2204
2117=item IO::AIO::tee $r_fh, $w_fh, $length, $flags 2205=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
2118 2206
2119Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the 2207Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
2120description for C<IO::AIO::splice> above for details. 2208description for C<IO::AIO::splice> above for details.
2209
2210=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
2211
2212Attempts to query or change the pipe buffer size. Obviously works only
2213on pipes, and currently works only on GNU/Linux systems, and fails with
2214C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
2215size on other systems, drop me a note.
2216
2217=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
2218
2219This is a direct interface to the Linux L<pipe2(2)> system call. If
2220C<$flags> is missing or C<0>, then this should be the same as a call to
2221perl's built-in C<pipe> function and create a new pipe, and works on
2222systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
2223(..., 4096, O_BINARY)>.
2224
2225If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
2226the given flags (Linux 2.6.27, glibc 2.9).
2227
2228On success, the read and write file handles are returned.
2229
2230On error, nothing will be returned. If the pipe2 syscall is missing and
2231C<$flags> is non-zero, fails with C<ENOSYS>.
2232
2233Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
2234time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
2235C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
2121 2236
2122=back 2237=back
2123 2238
2124=cut 2239=cut
2125 2240

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