ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/IO-AIO/README
(Generate patch)

Comparing IO-AIO/README (file contents):
Revision 1.26 by root, Thu Oct 4 12:50:35 2007 UTC vs.
Revision 1.43 by root, Sun Jan 10 23:44:02 2010 UTC

… …
24 $req->cancel; # cancel request if still in queue 24 $req->cancel; # cancel request if still in queue
25 25
26 my $grp = aio_group sub { print "all stats done\n" }; 26 my $grp = aio_group sub { print "all stats done\n" };
27 add $grp aio_stat "..." for ...; 27 add $grp aio_stat "..." for ...;
28 28
29 # AnyEvent integration
30 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
31 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32
33 # Event integration
34 Event->io (fd => IO::AIO::poll_fileno,
35 poll => 'r',
36 cb => \&IO::AIO::poll_cb);
37
38 # Glib/Gtk2 integration
39 add_watch Glib::IO IO::AIO::poll_fileno,
40 in => sub { IO::AIO::poll_cb; 1 };
41
42 # Tk integration
43 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
44 readable => \&IO::AIO::poll_cb);
45
46 # Danga::Socket integration
47 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
48 \&IO::AIO::poll_cb);
49
50DESCRIPTION 29DESCRIPTION
51 This module implements asynchronous I/O using whatever means your 30 This module implements asynchronous I/O using whatever means your
52 operating system supports. 31 operating system supports. It is implemented as an interface to "libeio"
32 (<http://software.schmorp.de/pkg/libeio.html>).
53 33
54 Asynchronous means that operations that can normally block your program 34 Asynchronous means that operations that can normally block your program
55 (e.g. reading from disk) will be done asynchronously: the operation will 35 (e.g. reading from disk) will be done asynchronously: the operation will
56 still block, but you can do something else in the meantime. This is 36 still block, but you can do something else in the meantime. This is
57 extremely useful for programs that need to stay interactive even when 37 extremely useful for programs that need to stay interactive even when
… …
62 operations concurrently. 42 operations concurrently.
63 43
64 While most of this works on all types of file descriptors (for example 44 While most of this works on all types of file descriptors (for example
65 sockets), using these functions on file descriptors that support 45 sockets), using these functions on file descriptors that support
66 nonblocking operation (again, sockets, pipes etc.) is very inefficient. 46 nonblocking operation (again, sockets, pipes etc.) is very inefficient.
67 Use an event loop for that (such as the Event module): IO::AIO will 47 Use an event loop for that (such as the EV module): IO::AIO will
68 naturally fit into such an event loop itself. 48 naturally fit into such an event loop itself.
69 49
70 In this version, a number of threads are started that execute your 50 In this version, a number of threads are started that execute your
71 requests and signal their completion. You don't need thread support in 51 requests and signal their completion. You don't need thread support in
72 perl, and the threads created by this module will not be visible to 52 perl, and the threads created by this module will not be visible to
… …
81 it is currently not reentrant in any way, so use appropriate locking 61 it is currently not reentrant in any way, so use appropriate locking
82 yourself, always call "poll_cb" from within the same thread, or never 62 yourself, always call "poll_cb" from within the same thread, or never
83 call "poll_cb" (or other "aio_" functions) recursively. 63 call "poll_cb" (or other "aio_" functions) recursively.
84 64
85 EXAMPLE 65 EXAMPLE
86 This is a simple example that uses the Event module and loads 66 This is a simple example that uses the EV module and loads /etc/passwd
87 /etc/passwd asynchronously: 67 asynchronously:
88 68
89 use Fcntl; 69 use Fcntl;
90 use Event; 70 use EV;
91 use IO::AIO; 71 use IO::AIO;
92 72
93 # register the IO::AIO callback with Event 73 # register the IO::AIO callback with EV
94 Event->io (fd => IO::AIO::poll_fileno, 74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
95 poll => 'r',
96 cb => \&IO::AIO::poll_cb);
97 75
98 # queue the request to open /etc/passwd 76 # queue the request to open /etc/passwd
99 aio_open "/etc/passwd", O_RDONLY, 0, sub { 77 aio_open "/etc/passwd", O_RDONLY, 0, sub {
100 my $fh = shift 78 my $fh = shift
101 or die "error while opening: $!"; 79 or die "error while opening: $!";
… …
113 91
114 # file contents now in $contents 92 # file contents now in $contents
115 print $contents; 93 print $contents;
116 94
117 # exit event loop and program 95 # exit event loop and program
118 Event::unloop; 96 EV::unloop;
119 }; 97 };
120 }; 98 };
121 99
122 # possibly queue up other requests, or open GUI windows, 100 # possibly queue up other requests, or open GUI windows,
123 # check for sockets etc. etc. 101 # check for sockets etc. etc.
124 102
125 # process events as long as there are some: 103 # process events as long as there are some:
126 Event::loop; 104 EV::loop;
127 105
128REQUEST ANATOMY AND LIFETIME 106REQUEST ANATOMY AND LIFETIME
129 Every "aio_*" function creates a request. which is a C data structure 107 Every "aio_*" function creates a request. which is a C data structure
130 not directly visible to Perl. 108 not directly visible to Perl.
131 109
… …
167 anymore (except possibly for the Perl object, but its connection to 145 anymore (except possibly for the Perl object, but its connection to
168 the actual aio request is severed and calling its methods will 146 the actual aio request is severed and calling its methods will
169 either do nothing or result in a runtime error). 147 either do nothing or result in a runtime error).
170 148
171FUNCTIONS 149FUNCTIONS
150 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions
152 for quick reference. See the following sections for function-by-function
153 documentation.
154
155 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status)
157 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160 aio_readahead $fh,$offset,$length, $callback->($retval)
161 aio_stat $fh_or_path, $callback->($status)
162 aio_lstat $fh, $callback->($status)
163 aio_statvfs $fh_or_path, $callback->($statvfs)
164 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
166 aio_truncate $fh_or_path, $offset, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status)
168 aio_unlink $pathname, $callback->($status)
169 aio_mknod $path, $mode, $dev, $callback->($status)
170 aio_link $srcpath, $dstpath, $callback->($status)
171 aio_symlink $srcpath, $dstpath, $callback->($status)
172 aio_readlink $path, $callback->($link)
173 aio_rename $srcpath, $dstpath, $callback->($status)
174 aio_mkdir $pathname, $mode, $callback->($status)
175 aio_rmdir $pathname, $callback->($status)
176 aio_readdir $pathname, $callback->($entries)
177 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
180 aio_load $path, $data, $callback->($status)
181 aio_copy $srcpath, $dstpath, $callback->($status)
182 aio_move $srcpath, $dstpath, $callback->($status)
183 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184 aio_rmtree $path, $callback->($status)
185 aio_sync $callback->($status)
186 aio_fsync $fh, $callback->($status)
187 aio_fdatasync $fh, $callback->($status)
188 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189 aio_pathsync $path, $callback->($status)
190 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
191 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_group $callback->(...)
193 aio_nop $callback->()
194
195 $prev_pri = aioreq_pri [$pri]
196 aioreq_nice $pri_adjust
197
198 IO::AIO::poll_wait
199 IO::AIO::poll_cb
200 IO::AIO::poll
201 IO::AIO::flush
202 IO::AIO::max_poll_reqs $nreqs
203 IO::AIO::max_poll_time $seconds
204 IO::AIO::min_parallel $nthreads
205 IO::AIO::max_parallel $nthreads
206 IO::AIO::max_idle $nthreads
207 IO::AIO::max_outstanding $maxreqs
208 IO::AIO::nreqs
209 IO::AIO::nready
210 IO::AIO::npending
211
212 IO::AIO::sendfile $ofh, $ifh, $offset, $count
213 IO::AIO::fadvise $fh, $offset, $len, $advice
214 IO::AIO::mlockall $flags
215 IO::AIO::munlockall
216
172 AIO REQUEST FUNCTIONS 217 AIO REQUEST FUNCTIONS
173 All the "aio_*" calls are more or less thin wrappers around the syscall 218 All the "aio_*" calls are more or less thin wrappers around the syscall
174 with the same name (sans "aio_"). The arguments are similar or 219 with the same name (sans "aio_"). The arguments are similar or
175 identical, and they all accept an additional (and optional) $callback 220 identical, and they all accept an additional (and optional) $callback
176 argument which must be a code reference. This code reference will get 221 argument which must be a code reference. This code reference will get
177 called with the syscall return code (e.g. most syscalls return -1 on 222 called with the syscall return code (e.g. most syscalls return -1 on
178 error, unlike perl, which usually delivers "false") as it's sole 223 error, unlike perl, which usually delivers "false") as its sole argument
179 argument when the given syscall has been executed asynchronously. 224 after the given syscall has been executed asynchronously.
180 225
181 All functions expecting a filehandle keep a copy of the filehandle 226 All functions expecting a filehandle keep a copy of the filehandle
182 internally until the request has finished. 227 internally until the request has finished.
183 228
184 All functions return request objects of type IO::AIO::REQ that allow 229 All functions return request objects of type IO::AIO::REQ that allow
… …
197 the user environment, d) use Glib::filename_from_unicode on unicode 242 the user environment, d) use Glib::filename_from_unicode on unicode
198 filenames or e) use something else to ensure your scalar has the correct 243 filenames or e) use something else to ensure your scalar has the correct
199 contents. 244 contents.
200 245
201 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 246 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
202 handles correctly wether it is set or not. 247 handles correctly whether it is set or not.
203 248
204 $prev_pri = aioreq_pri [$pri] 249 $prev_pri = aioreq_pri [$pri]
205 Returns the priority value that would be used for the next request 250 Returns the priority value that would be used for the next request
206 and, if $pri is given, sets the priority for the next aio request. 251 and, if $pri is given, sets the priority for the next aio request.
207 252
… …
260 305
261 aio_close $fh, $callback->($status) 306 aio_close $fh, $callback->($status)
262 Asynchronously close a file and call the callback with the result 307 Asynchronously close a file and call the callback with the result
263 code. 308 code.
264 309
265 Unlike the other functions operating on files, this function uses 310 Unfortunately, you can't do this to perl. Perl *insists* very
266 the PerlIO layer to close the filehandle. The reason is that the 311 strongly on closing the file descriptor associated with the
267 PerlIO API insists on closing the underlying fd itself, no matter 312 filehandle itself.
268 what, and doesn't allow modifications to the fd. Unfortunately, it
269 is not clear that you can call PerlIO from different threads
270 (actually, its quite clear that this won't work in some cases), so
271 while it likely works perfectly with simple file handles (such as
272 the ones created by "aio_open") it might fail in interesting ways
273 for others.
274 313
275 Having said that, aio_close tries to clean up the filehandle as much 314 Therefore, "aio_close" will not close the filehandle - instead it
276 as possible before handing it to an io thread, and generally does 315 will use dup2 to overwrite the file descriptor with the write-end of
277 work. 316 a pipe (the pipe fd will be created on demand and will be cached).
317
318 Or in other words: the file descriptor will be closed, but it will
319 not be free for reuse until the perl filehandle is closed.
278 320
279 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 321 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
280 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 322 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
281 Reads or writes $length bytes from the specified $fh and $offset 323 Reads or writes $length bytes from or to the specified $fh and
282 into the scalar given by $data and offset $dataoffset and calls the 324 $offset into the scalar given by $data and offset $dataoffset and
283 callback without the actual number of bytes read (or -1 on error, 325 calls the callback without the actual number of bytes read (or -1 on
284 just like the syscall). 326 error, just like the syscall).
327
328 "aio_read" will, like "sysread", shrink or grow the $data scalar to
329 offset plus the actual number of bytes read.
285 330
286 If $offset is undefined, then the current file descriptor offset 331 If $offset is undefined, then the current file descriptor offset
287 will be used (and updated), otherwise the file descriptor offset 332 will be used (and updated), otherwise the file descriptor offset
288 will not be changed by these calls. 333 will not be changed by these calls.
289 334
… …
312 more than one "aio_sendfile" per $out_fh, as they will interfere 357 more than one "aio_sendfile" per $out_fh, as they will interfere
313 with each other. 358 with each other.
314 359
315 This call tries to make use of a native "sendfile" syscall to 360 This call tries to make use of a native "sendfile" syscall to
316 provide zero-copy operation. For this to work, $out_fh should refer 361 provide zero-copy operation. For this to work, $out_fh should refer
317 to a socket, and $in_fh should refer to mmap'able file. 362 to a socket, and $in_fh should refer to an mmap'able file.
318 363
319 If the native sendfile call fails or is not implemented, it will be 364 If a native sendfile cannot be found or it fails with "ENOSYS",
365 "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",
320 emulated, so you can call "aio_sendfile" on any type of filehandle 366 it will be emulated, so you can call "aio_sendfile" on any type of
321 regardless of the limitations of the operating system. 367 filehandle regardless of the limitations of the operating system.
322 368
323 Please note, however, that "aio_sendfile" can read more bytes from 369 Please note, however, that "aio_sendfile" can read more bytes from
324 $in_fh than are written, and there is no way to find out how many 370 $in_fh than are written, and there is no way to find out how many
325 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 371 bytes have been read from "aio_sendfile" alone, as "aio_sendfile"
326 only provides the number of bytes written to $out_fh. Only if the 372 only provides the number of bytes written to $out_fh. Only if the
… …
361 aio_stat "/etc/passwd", sub { 407 aio_stat "/etc/passwd", sub {
362 $_[0] and die "stat failed: $!"; 408 $_[0] and die "stat failed: $!";
363 print "size is ", -s _, "\n"; 409 print "size is ", -s _, "\n";
364 }; 410 };
365 411
412 aio_statvfs $fh_or_path, $callback->($statvfs)
413 Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
414 whether a file handle or path was passed.
415
416 On success, the callback is passed a hash reference with the
417 following members: "bsize", "frsize", "blocks", "bfree", "bavail",
418 "files", "ffree", "favail", "fsid", "flag" and "namemax". On
419 failure, "undef" is passed.
420
421 The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
422 and "ST_NOSUID".
423
424 The following non-POSIX IO::AIO::ST_* flag masks are defined to
425 their correct value when available, or to 0 on systems that do not
426 support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
427 "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
428 "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
429
430 Example: stat "/wd" and dump out the data if successful.
431
432 aio_statvfs "/wd", sub {
433 my $f = $_[0]
434 or die "statvfs: $!";
435
436 use Data::Dumper;
437 say Dumper $f;
438 };
439
440 # result:
441 {
442 bsize => 1024,
443 bfree => 4333064312,
444 blocks => 10253828096,
445 files => 2050765568,
446 flag => 4096,
447 favail => 2042092649,
448 bavail => 4333064312,
449 ffree => 2042092649,
450 namemax => 255,
451 frsize => 1024,
452 fsid => 1810
453 }
454
366 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 455 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
367 Works like perl's "utime" function (including the special case of 456 Works like perl's "utime" function (including the special case of
368 $atime and $mtime being undef). Fractional times are supported if 457 $atime and $mtime being undef). Fractional times are supported if
369 the underlying syscalls support them. 458 the underlying syscalls support them.
370 459
… …
440 aio_readdir $pathname, $callback->($entries) 529 aio_readdir $pathname, $callback->($entries)
441 Unlike the POSIX call of the same name, "aio_readdir" reads an 530 Unlike the POSIX call of the same name, "aio_readdir" reads an
442 entire directory (i.e. opendir + readdir + closedir). The entries 531 entire directory (i.e. opendir + readdir + closedir). The entries
443 will not be sorted, and will NOT include the "." and ".." entries. 532 will not be sorted, and will NOT include the "." and ".." entries.
444 533
445 The callback a single argument which is either "undef" or an 534 The callback is passed a single argument which is either "undef" or
446 array-ref with the filenames. 535 an array-ref with the filenames.
536
537 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
538 Quite similar to "aio_readdir", but the $flags argument allows to
539 tune behaviour and output format. In case of an error, $entries will
540 be "undef".
541
542 The flags are a combination of the following constants, ORed
543 together (the flags will also be passed to the callback, possibly
544 modified):
545
546 IO::AIO::READDIR_DENTS
547 When this flag is off, then the callback gets an arrayref with
548 of names only (as with "aio_readdir"), otherwise it gets an
549 arrayref with "[$name, $type, $inode]" arrayrefs, each
550 describing a single directory entry in more detail.
551
552 $name is the name of the entry.
553
554 $type is one of the "IO::AIO::DT_xxx" constants:
555
556 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
557 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
558 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
559
560 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
561 you need to know, you have to run stat yourself. Also, for speed
562 reasons, the $type scalars are read-only: you can not modify
563 them.
564
565 $inode is the inode number (which might not be exact on systems
566 with 64 bit inode numbers and 32 bit perls). This field has
567 unspecified content on systems that do not deliver the inode
568 information.
569
570 IO::AIO::READDIR_DIRS_FIRST
571 When this flag is set, then the names will be returned in an
572 order where likely directories come first. This is useful when
573 you need to quickly find directories, or you want to find all
574 directories while avoiding to stat() each entry.
575
576 If the system returns type information in readdir, then this is
577 used to find directories directly. Otherwise, likely directories
578 are files beginning with ".", or otherwise files with no dots,
579 of which files with short names are tried first.
580
581 IO::AIO::READDIR_STAT_ORDER
582 When this flag is set, then the names will be returned in an
583 order suitable for stat()'ing each one. That is, when you plan
584 to stat() all files in the given directory, then the returned
585 order will likely be fastest.
586
587 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
588 specified, then the likely dirs come first, resulting in a less
589 optimal stat order.
590
591 IO::AIO::READDIR_FOUND_UNKNOWN
592 This flag should not be set when calling "aio_readdirx".
593 Instead, it is being set by "aio_readdirx", when any of the
594 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this
595 flag therefore indicates that all $type's are known, which can
596 be used to speed up some algorithms.
447 597
448 aio_load $path, $data, $callback->($status) 598 aio_load $path, $data, $callback->($status)
449 This is a composite request that tries to fully load the given file 599 This is a composite request that tries to fully load the given file
450 into memory. Status is the same as with aio_read. 600 into memory. Status is the same as with aio_read.
451 601
452 aio_copy $srcpath, $dstpath, $callback->($status) 602 aio_copy $srcpath, $dstpath, $callback->($status)
453 Try to copy the *file* (directories not supported as either source 603 Try to copy the *file* (directories not supported as either source
454 or destination) from $srcpath to $dstpath and call the callback with 604 or destination) from $srcpath to $dstpath and call the callback with
455 the 0 (error) or -1 ok. 605 a status of 0 (ok) or -1 (error, see $!).
456 606
457 This is a composite request that it creates the destination file 607 This is a composite request that creates the destination file with
458 with mode 0200 and copies the contents of the source file into it 608 mode 0200 and copies the contents of the source file into it using
459 using "aio_sendfile", followed by restoring atime, mtime, access 609 "aio_sendfile", followed by restoring atime, mtime, access mode and
460 mode and uid/gid, in that order. 610 uid/gid, in that order.
461 611
462 If an error occurs, the partial destination file will be unlinked, 612 If an error occurs, the partial destination file will be unlinked,
463 if possible, except when setting atime, mtime, access mode and 613 if possible, except when setting atime, mtime, access mode and
464 uid/gid, where errors are being ignored. 614 uid/gid, where errors are being ignored.
465 615
466 aio_move $srcpath, $dstpath, $callback->($status) 616 aio_move $srcpath, $dstpath, $callback->($status)
467 Try to move the *file* (directories not supported as either source 617 Try to move the *file* (directories not supported as either source
468 or destination) from $srcpath to $dstpath and call the callback with 618 or destination) from $srcpath to $dstpath and call the callback with
469 the 0 (error) or -1 ok. 619 a status of 0 (ok) or -1 (error, see $!).
470 620
471 This is a composite request that tries to rename(2) the file first. 621 This is a composite request that tries to rename(2) the file first;
472 If rename files with "EXDEV", it copies the file with "aio_copy" 622 if rename fails with "EXDEV", it copies the file with "aio_copy"
473 and, if that is successful, unlinking the $srcpath. 623 and, if that is successful, unlinks the $srcpath.
474 624
475 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 625 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
476 Scans a directory (similar to "aio_readdir") but additionally tries 626 Scans a directory (similar to "aio_readdir") but additionally tries
477 to efficiently separate the entries of directory $path into two sets 627 to efficiently separate the entries of directory $path into two sets
478 of names, directories you can recurse into (directories), and ones 628 of names, directories you can recurse into (directories), and ones
… …
498 Implementation notes. 648 Implementation notes.
499 649
500 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry 650 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
501 can. 651 can.
502 652
653 If readdir returns file type information, then this is used directly
654 to find directories.
655
503 After reading the directory, the modification time, size etc. of the 656 Otherwise, after reading the directory, the modification time, size
504 directory before and after the readdir is checked, and if they match 657 etc. of the directory before and after the readdir is checked, and
505 (and isn't the current time), the link count will be used to decide 658 if they match (and isn't the current time), the link count will be
506 how many entries are directories (if >= 2). Otherwise, no knowledge 659 used to decide how many entries are directories (if >= 2).
507 of the number of subdirectories will be assumed. 660 Otherwise, no knowledge of the number of subdirectories will be
661 assumed.
508 662
509 Then entries will be sorted into likely directories (everything 663 Then entries will be sorted into likely directories a non-initial
510 without a non-initial dot currently) and likely non-directories 664 dot currently) and likely non-directories (see "aio_readdirx"). Then
511 (everything else). Then every entry plus an appended "/." will be 665 every entry plus an appended "/." will be "stat"'ed, likely
512 "stat"'ed, likely directories first. If that succeeds, it assumes 666 directories first, in order of their inode numbers. If that
513 that the entry is a directory or a symlink to directory (which will 667 succeeds, it assumes that the entry is a directory or a symlink to
514 be checked seperately). This is often faster than stat'ing the entry 668 directory (which will be checked seperately). This is often faster
515 itself because filesystems might detect the type of the entry 669 than stat'ing the entry itself because filesystems might detect the
516 without reading the inode data (e.g. ext2fs filetype feature). 670 type of the entry without reading the inode data (e.g. ext2fs
671 filetype feature), even on systems that cannot return the filetype
672 information on readdir.
517 673
518 If the known number of directories (link count - 2) has been 674 If the known number of directories (link count - 2) has been
519 reached, the rest of the entries is assumed to be non-directories. 675 reached, the rest of the entries is assumed to be non-directories.
520 676
521 This only works with certainty on POSIX (= UNIX) filesystems, which 677 This only works with certainty on POSIX (= UNIX) filesystems, which
… …
529 Delete a directory tree starting (and including) $path, return the 685 Delete a directory tree starting (and including) $path, return the
530 status of the final "rmdir" only. This is a composite request that 686 status of the final "rmdir" only. This is a composite request that
531 uses "aio_scandir" to recurse into and rmdir directories, and unlink 687 uses "aio_scandir" to recurse into and rmdir directories, and unlink
532 everything else. 688 everything else.
533 689
690 aio_sync $callback->($status)
691 Asynchronously call sync and call the callback when finished.
692
534 aio_fsync $fh, $callback->($status) 693 aio_fsync $fh, $callback->($status)
535 Asynchronously call fsync on the given filehandle and call the 694 Asynchronously call fsync on the given filehandle and call the
536 callback with the fsync result code. 695 callback with the fsync result code.
537 696
538 aio_fdatasync $fh, $callback->($status) 697 aio_fdatasync $fh, $callback->($status)
539 Asynchronously call fdatasync on the given filehandle and call the 698 Asynchronously call fdatasync on the given filehandle and call the
540 callback with the fdatasync result code. 699 callback with the fdatasync result code.
541 700
542 If this call isn't available because your OS lacks it or it couldn't 701 If this call isn't available because your OS lacks it or it couldn't
543 be detected, it will be emulated by calling "fsync" instead. 702 be detected, it will be emulated by calling "fsync" instead.
703
704 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
705 Sync the data portion of the file specified by $offset and $length
706 to disk (but NOT the metadata), by calling the Linux-specific
707 sync_file_range call. If sync_file_range is not available or it
708 returns ENOSYS, then fdatasync or fsync is being substituted.
709
710 $flags can be a combination of
711 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
712 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
713 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
714 manpage for details.
715
716 aio_pathsync $path, $callback->($status)
717 This request tries to open, fsync and close the given path. This is
718 a composite request intended to sync directories after directory
719 operations (E.g. rename). This might not work on all operating
720 systems or have any specific effect, but usually it makes sure that
721 directory changes get written to disc. It works for anything that
722 can be opened for read-only, not just directories.
723
724 Future versions of this function might fall back to other methods
725 when "fsync" on the directory fails (such as calling "sync").
726
727 Passes 0 when everything went ok, and -1 on error.
728
729 aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
730 $callback->($status)
731 This is a rather advanced IO::AIO call, which only works on
732 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
733 also works on data scalars managed by the Sys::Mmap or Mmap modules,
734 note that the scalar must only be modified in-place while an aio
735 operation is pending on it).
736
737 It calls the "msync" function of your OS, if available, with the
738 memory area starting at $offset in the string and ending $length
739 bytes later. If $length is negative, counts from the end, and if
740 $length is "undef", then it goes till the end of the string. The
741 flags can be a combination of "IO::AIO::MS_ASYNC",
742 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
743
744 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
745 $callback->($status)
746 This is a rather advanced IO::AIO call, which works best on
747 mmap(2)ed scalars.
748
749 It touches (reads or writes) all memory pages in the specified range
750 inside the scalar. All caveats and parameters are the same as for
751 "aio_msync", above, except for flags, which must be either 0 (which
752 reads all pages and ensures they are instantiated) or
753 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
754 and writing an octet from it, which dirties the page).
544 755
545 aio_group $callback->(...) 756 aio_group $callback->(...)
546 This is a very special aio request: Instead of doing something, it 757 This is a very special aio request: Instead of doing something, it
547 is a container for other aio requests, which is useful if you want 758 is a container for other aio requests, which is useful if you want
548 to bundle many requests into a single, composite, request with a 759 to bundle many requests into a single, composite, request with a
… …
591 802
592 cancel $req 803 cancel $req
593 Cancels the request, if possible. Has the effect of skipping 804 Cancels the request, if possible. Has the effect of skipping
594 execution when entering the execute state and skipping calling the 805 execution when entering the execute state and skipping calling the
595 callback when entering the the result state, but will leave the 806 callback when entering the the result state, but will leave the
596 request otherwise untouched. That means that requests that currently 807 request otherwise untouched (with the exception of readdir). That
597 execute will not be stopped and resources held by the request will 808 means that requests that currently execute will not be stopped and
598 not be freed prematurely. 809 resources held by the request will not be freed prematurely.
599 810
600 cb $req $callback->(...) 811 cb $req $callback->(...)
601 Replace (or simply set) the callback registered to the request. 812 Replace (or simply set) the callback registered to the request.
602 813
603 IO::AIO::GRP CLASS 814 IO::AIO::GRP CLASS
… …
630 }; 841 };
631 842
632 This makes it very easy to create composite requests (see the source of 843 This makes it very easy to create composite requests (see the source of
633 "aio_move" for an application) that work and feel like simple requests. 844 "aio_move" for an application) that work and feel like simple requests.
634 845
635 * The IO::AIO::GRP objects will be cleaned up during calls to 846 * The IO::AIO::GRP objects will be cleaned up during calls to
636 "IO::AIO::poll_cb", just like any other request. 847 "IO::AIO::poll_cb", just like any other request.
848
637 * They can be canceled like any other request. Canceling will cancel not 849 * They can be canceled like any other request. Canceling will cancel
638 only the request itself, but also all requests it contains. 850 not only the request itself, but also all requests it contains.
851
639 * They can also can also be added to other IO::AIO::GRP objects. 852 * They can also can also be added to other IO::AIO::GRP objects.
853
640 * You must not add requests to a group from within the group callback 854 * You must not add requests to a group from within the group callback
641 (or any later time). 855 (or any later time).
642 856
643 Their lifetime, simplified, looks like this: when they are empty, they 857 Their lifetime, simplified, looks like this: when they are empty, they
644 will finish very quickly. If they contain only requests that are in the 858 will finish very quickly. If they contain only requests that are in the
645 "done" state, they will also finish. Otherwise they will continue to 859 "done" state, they will also finish. Otherwise they will continue to
646 exist. 860 exist.
647 861
648 That means after creating a group you have some time to add requests. 862 That means after creating a group you have some time to add requests
649 And in the callbacks of those requests, you can add further requests to 863 (precisely before the callback has been invoked, which is only done
650 the group. And only when all those requests have finished will the the 864 within the "poll_cb"). And in the callbacks of those requests, you can
651 group itself finish. 865 add further requests to the group. And only when all those requests have
866 finished will the the group itself finish.
652 867
653 add $grp ... 868 add $grp ...
654 $grp->add (...) 869 $grp->add (...)
655 Add one or more requests to the group. Any type of IO::AIO::REQ can 870 Add one or more requests to the group. Any type of IO::AIO::REQ can
656 be added, including other groups, as long as you do not create 871 be added, including other groups, as long as you do not create
… …
661 $grp->cancel_subs 876 $grp->cancel_subs
662 Cancel all subrequests and clears any feeder, but not the group 877 Cancel all subrequests and clears any feeder, but not the group
663 request itself. Useful when you queued a lot of events but got a 878 request itself. Useful when you queued a lot of events but got a
664 result early. 879 result early.
665 880
881 The group request will finish normally (you cannot add requests to
882 the group).
883
666 $grp->result (...) 884 $grp->result (...)
667 Set the result value(s) that will be passed to the group callback 885 Set the result value(s) that will be passed to the group callback
668 when all subrequests have finished and set thre groups errno to the 886 when all subrequests have finished and set the groups errno to the
669 current value of errno (just like calling "errno" without an error 887 current value of errno (just like calling "errno" without an error
670 number). By default, no argument will be passed and errno is zero. 888 number). By default, no argument will be passed and errno is zero.
671 889
672 $grp->errno ([$errno]) 890 $grp->errno ([$errno])
673 Sets the group errno value to $errno, or the current value of errno 891 Sets the group errno value to $errno, or the current value of errno
… …
699 does not impose any limits). 917 does not impose any limits).
700 918
701 If the feed does not queue more requests when called, it will be 919 If the feed does not queue more requests when called, it will be
702 automatically removed from the group. 920 automatically removed from the group.
703 921
704 If the feed limit is 0, it will be set to 2 automatically. 922 If the feed limit is 0 when this method is called, it will be set to
923 2 automatically.
705 924
706 Example: 925 Example:
707 926
708 # stat all files in @files, but only ever use four aio requests concurrently: 927 # stat all files in @files, but only ever use four aio requests concurrently:
709 928
… …
720 Sets the feeder limit for the group: The feeder will be called 939 Sets the feeder limit for the group: The feeder will be called
721 whenever the group contains less than this many requests. 940 whenever the group contains less than this many requests.
722 941
723 Setting the limit to 0 will pause the feeding process. 942 Setting the limit to 0 will pause the feeding process.
724 943
944 The default value for the limit is 0, but note that setting a feeder
945 automatically bumps it up to 2.
946
725 SUPPORT FUNCTIONS 947 SUPPORT FUNCTIONS
726 EVENT PROCESSING AND EVENT LOOP INTEGRATION 948 EVENT PROCESSING AND EVENT LOOP INTEGRATION
727 $fileno = IO::AIO::poll_fileno 949 $fileno = IO::AIO::poll_fileno
728 Return the *request result pipe file descriptor*. This filehandle 950 Return the *request result pipe file descriptor*. This filehandle
729 must be polled for reading by some mechanism outside this module 951 must be polled for reading by some mechanism outside this module
730 (e.g. Event or select, see below or the SYNOPSIS). If the pipe 952 (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
731 becomes readable you have to call "poll_cb" to check the results. 953 pipe becomes readable you have to call "poll_cb" to check the
954 results.
732 955
733 See "poll_cb" for an example. 956 See "poll_cb" for an example.
734 957
735 IO::AIO::poll_cb 958 IO::AIO::poll_cb
736 Process some outstanding events on the result pipe. You have to call 959 Process some outstanding events on the result pipe. You have to call
737 this regularly. Returns the number of events processed. Returns 960 this regularly. Returns 0 if all events could be processed, or -1 if
738 immediately when no events are outstanding. The amount of events 961 it returned earlier for whatever reason. Returns immediately when no
962 events are outstanding. The amount of events processed depends on
739 processed depends on the settings of "IO::AIO::max_poll_req" and 963 the settings of "IO::AIO::max_poll_req" and
740 "IO::AIO::max_poll_time". 964 "IO::AIO::max_poll_time".
741 965
742 If not all requests were processed for whatever reason, the 966 If not all requests were processed for whatever reason, the
743 filehandle will still be ready when "poll_cb" returns. 967 filehandle will still be ready when "poll_cb" returns, so normally
968 you don't have to do anything special to have it called later.
744 969
745 Example: Install an Event watcher that automatically calls 970 Example: Install an Event watcher that automatically calls
746 IO::AIO::poll_cb with high priority: 971 IO::AIO::poll_cb with high priority (more examples can be found in
972 the SYNOPSIS section, at the top of this document):
747 973
748 Event->io (fd => IO::AIO::poll_fileno, 974 Event->io (fd => IO::AIO::poll_fileno,
749 poll => 'r', async => 1, 975 poll => 'r', async => 1,
750 cb => \&IO::AIO::poll_cb); 976 cb => \&IO::AIO::poll_cb);
977
978 IO::AIO::poll_wait
979 If there are any outstanding requests and none of them in the result
980 phase, wait till the result filehandle becomes ready for reading
981 (simply does a "select" on the filehandle. This is useful if you
982 want to synchronously wait for some requests to finish).
983
984 See "nreqs" for an example.
985
986 IO::AIO::poll
987 Waits until some requests have been handled.
988
989 Returns the number of requests processed, but is otherwise strictly
990 equivalent to:
991
992 IO::AIO::poll_wait, IO::AIO::poll_cb
993
994 IO::AIO::flush
995 Wait till all outstanding AIO requests have been handled.
996
997 Strictly equivalent to:
998
999 IO::AIO::poll_wait, IO::AIO::poll_cb
1000 while IO::AIO::nreqs;
751 1001
752 IO::AIO::max_poll_reqs $nreqs 1002 IO::AIO::max_poll_reqs $nreqs
753 IO::AIO::max_poll_time $seconds 1003 IO::AIO::max_poll_time $seconds
754 These set the maximum number of requests (default 0, meaning 1004 These set the maximum number of requests (default 0, meaning
755 infinity) that are being processed by "IO::AIO::poll_cb" in one 1005 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
779 # use a low priority so other tasks have priority 1029 # use a low priority so other tasks have priority
780 Event->io (fd => IO::AIO::poll_fileno, 1030 Event->io (fd => IO::AIO::poll_fileno,
781 poll => 'r', nice => 1, 1031 poll => 'r', nice => 1,
782 cb => &IO::AIO::poll_cb); 1032 cb => &IO::AIO::poll_cb);
783 1033
784 IO::AIO::poll_wait
785 If there are any outstanding requests and none of them in the result
786 phase, wait till the result filehandle becomes ready for reading
787 (simply does a "select" on the filehandle. This is useful if you
788 want to synchronously wait for some requests to finish).
789
790 See "nreqs" for an example.
791
792 IO::AIO::poll
793 Waits until some requests have been handled.
794
795 Returns the number of requests processed, but is otherwise strictly
796 equivalent to:
797
798 IO::AIO::poll_wait, IO::AIO::poll_cb
799
800 IO::AIO::flush
801 Wait till all outstanding AIO requests have been handled.
802
803 Strictly equivalent to:
804
805 IO::AIO::poll_wait, IO::AIO::poll_cb
806 while IO::AIO::nreqs;
807
808 CONTROLLING THE NUMBER OF THREADS 1034 CONTROLLING THE NUMBER OF THREADS
809 IO::AIO::min_parallel $nthreads 1035 IO::AIO::min_parallel $nthreads
810 Set the minimum number of AIO threads to $nthreads. The current 1036 Set the minimum number of AIO threads to $nthreads. The current
811 default is 8, which means eight asynchronous operations can execute 1037 default is 8, which means eight asynchronous operations can execute
812 concurrently at any one time (the number of outstanding requests, 1038 concurrently at any one time (the number of outstanding requests,
… …
854 1080
855 The default is probably ok in most situations, especially if thread 1081 The default is probably ok in most situations, especially if thread
856 creation is fast. If thread creation is very slow on your system you 1082 creation is fast. If thread creation is very slow on your system you
857 might want to use larger values. 1083 might want to use larger values.
858 1084
859 $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1085 IO::AIO::max_outstanding $maxreqs
860 This is a very bad function to use in interactive programs because 1086 This is a very bad function to use in interactive programs because
861 it blocks, and a bad way to reduce concurrency because it is 1087 it blocks, and a bad way to reduce concurrency because it is
862 inexact: Better use an "aio_group" together with a feed callback. 1088 inexact: Better use an "aio_group" together with a feed callback.
863 1089
864 Sets the maximum number of outstanding requests to $nreqs. If you do 1090 Sets the maximum number of outstanding requests to $nreqs. If you do
… …
868 1094
869 The default value is very large, so there is no practical limit on 1095 The default value is very large, so there is no practical limit on
870 the number of outstanding requests. 1096 the number of outstanding requests.
871 1097
872 You can still queue as many requests as you want. Therefore, 1098 You can still queue as many requests as you want. Therefore,
873 "max_oustsanding" is mainly useful in simple scripts (with low 1099 "max_outstanding" is mainly useful in simple scripts (with low
874 values) or as a stop gap to shield against fatal memory overflow 1100 values) or as a stop gap to shield against fatal memory overflow
875 (with large values). 1101 (with large values).
876 1102
877 STATISTICAL INFORMATION 1103 STATISTICAL INFORMATION
878 IO::AIO::nreqs 1104 IO::AIO::nreqs
… …
890 executed). 1116 executed).
891 1117
892 IO::AIO::npending 1118 IO::AIO::npending
893 Returns the number of requests currently in the pending state 1119 Returns the number of requests currently in the pending state
894 (executed, but not yet processed by poll_cb). 1120 (executed, but not yet processed by poll_cb).
1121
1122 MISCELLANEOUS FUNCTIONS
1123 IO::AIO implements some functions that might be useful, but are not
1124 asynchronous.
1125
1126 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1127 Calls the "eio_sendfile_sync" function, which is like
1128 "aio_sendfile", but is blocking (this makes most sense if you know
1129 the input data is likely cached already and the output filehandle is
1130 set to non-blocking operations).
1131
1132 Returns the number of bytes copied, or -1 on error.
1133
1134 IO::AIO::fadvise $fh, $offset, $len, $advice
1135 Simply calls the "posix_fadvise" function (see it's manpage for
1136 details). The following advice constants are avaiable:
1137 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1138 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1139 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1140
1141 On systems that do not implement "posix_fadvise", this function
1142 returns ENOSYS, otherwise the return value of "posix_fadvise".
1143
1144 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1145 Memory-maps a file (or anonymous memory range) and attaches it to
1146 the given $scalar, which will act like a string scalar.
1147
1148 The only operations allowed on the scalar are "substr"/"vec" that
1149 don't change the string length, and most read-only operations such
1150 as copying it or searching it with regexes and so on.
1151
1152 Anything else is unsafe and will, at best, result in memory leaks.
1153
1154 The memory map associated with the $scalar is automatically removed
1155 when the $scalar is destroyed, or when the "IO::AIO::mmap" or
1156 "IO::AIO::munmap" functions are called.
1157
1158 This calls the "mmap"(2) function internally. See your system's
1159 manual page for details on the $length, $prot and $flags parameters.
1160
1161 The $length must be larger than zero and smaller than the actual
1162 filesize.
1163
1164 $prot is a combination of "IO::AIO::PROT_NONE",
1165 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1166 "IO::AIO::PROT_WRITE",
1167
1168 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1169 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1170 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
1171 (which is set to "MAP_ANON" if your system only provides this
1172 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
1173 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
1174 "IO::AIO::MAP_NONBLOCK"
1175
1176 If $fh is "undef", then a file descriptor of -1 is passed.
1177
1178 $offset is the offset from the start of the file - it generally must
1179 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1180
1181 Example:
1182
1183 use Digest::MD5;
1184 use IO::AIO;
1185
1186 open my $fh, "<verybigfile"
1187 or die "$!";
1188
1189 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1190 or die "verybigfile: $!";
1191
1192 my $fast_md5 = md5 $data;
1193
1194 IO::AIO::munmap $scalar
1195 Removes a previous mmap and undefines the $scalar.
1196
1197 IO::AIO::mlockall $flags
1198 Calls the "mlockall" function with the given $flags (a combination
1199 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL__FUTURE").
1200
1201 On systems that do not implement "mlockall", this function returns
1202 ENOSYS, otherwise the return value of "mlockall".
1203
1204 IO::AIO::munlockall
1205 Calls the "munlockall" function.
1206
1207 On systems that do not implement "munlockall", this function returns
1208 ENOSYS, otherwise the return value of "munlockall".
1209
1210EVENT LOOP INTEGRATION
1211 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1212 automatically into many event loops:
1213
1214 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1215 use AnyEvent::AIO;
1216
1217 You can also integrate IO::AIO manually into many event loops, here are
1218 some examples of how to do this:
1219
1220 # EV integration
1221 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1222
1223 # Event integration
1224 Event->io (fd => IO::AIO::poll_fileno,
1225 poll => 'r',
1226 cb => \&IO::AIO::poll_cb);
1227
1228 # Glib/Gtk2 integration
1229 add_watch Glib::IO IO::AIO::poll_fileno,
1230 in => sub { IO::AIO::poll_cb; 1 };
1231
1232 # Tk integration
1233 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1234 readable => \&IO::AIO::poll_cb);
1235
1236 # Danga::Socket integration
1237 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1238 \&IO::AIO::poll_cb);
895 1239
896 FORK BEHAVIOUR 1240 FORK BEHAVIOUR
897 This module should do "the right thing" when the process using it forks: 1241 This module should do "the right thing" when the process using it forks:
898 1242
899 Before the fork, IO::AIO enters a quiescent state where no requests can 1243 Before the fork, IO::AIO enters a quiescent state where no requests can
… …
928 1272
929KNOWN BUGS 1273KNOWN BUGS
930 Known bugs will be fixed in the next release. 1274 Known bugs will be fixed in the next release.
931 1275
932SEE ALSO 1276SEE ALSO
933 Coro::AIO. 1277 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1278 more natural syntax.
934 1279
935AUTHOR 1280AUTHOR
936 Marc Lehmann <schmorp@schmorp.de> 1281 Marc Lehmann <schmorp@schmorp.de>
937 http://home.schmorp.de/ 1282 http://home.schmorp.de/
938 1283

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines