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Revision 1.43 by root, Sun Jan 10 23:44:02 2010 UTC

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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 (EV, Event, Glib, Tk, urxvt, pureperl...)
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 # EV integration
34 my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
35
36 # Event integration
37 Event->io (fd => IO::AIO::poll_fileno,
38 poll => 'r',
39 cb => \&IO::AIO::poll_cb);
40
41 # Glib/Gtk2 integration
42 add_watch Glib::IO IO::AIO::poll_fileno,
43 in => sub { IO::AIO::poll_cb; 1 };
44
45 # Tk integration
46 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
47 readable => \&IO::AIO::poll_cb);
48
49 # Danga::Socket integration
50 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
51 \&IO::AIO::poll_cb);
52
53DESCRIPTION 29DESCRIPTION
54 This module implements asynchronous I/O using whatever means your 30 This module implements asynchronous I/O using whatever means your
55 operating system supports. 31 operating system supports. It is implemented as an interface to "libeio"
32 (<http://software.schmorp.de/pkg/libeio.html>).
56 33
57 Asynchronous means that operations that can normally block your program 34 Asynchronous means that operations that can normally block your program
58 (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
59 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
60 extremely useful for programs that need to stay interactive even when 37 extremely useful for programs that need to stay interactive even when
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65 operations concurrently. 42 operations concurrently.
66 43
67 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
68 sockets), using these functions on file descriptors that support 45 sockets), using these functions on file descriptors that support
69 nonblocking operation (again, sockets, pipes etc.) is very inefficient. 46 nonblocking operation (again, sockets, pipes etc.) is very inefficient.
70 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
71 naturally fit into such an event loop itself. 48 naturally fit into such an event loop itself.
72 49
73 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
74 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
75 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
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84 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
85 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
86 call "poll_cb" (or other "aio_" functions) recursively. 63 call "poll_cb" (or other "aio_" functions) recursively.
87 64
88 EXAMPLE 65 EXAMPLE
89 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
90 /etc/passwd asynchronously: 67 asynchronously:
91 68
92 use Fcntl; 69 use Fcntl;
93 use Event; 70 use EV;
94 use IO::AIO; 71 use IO::AIO;
95 72
96 # register the IO::AIO callback with Event 73 # register the IO::AIO callback with EV
97 Event->io (fd => IO::AIO::poll_fileno, 74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98 poll => 'r',
99 cb => \&IO::AIO::poll_cb);
100 75
101 # queue the request to open /etc/passwd 76 # queue the request to open /etc/passwd
102 aio_open "/etc/passwd", O_RDONLY, 0, sub { 77 aio_open "/etc/passwd", O_RDONLY, 0, sub {
103 my $fh = shift 78 my $fh = shift
104 or die "error while opening: $!"; 79 or die "error while opening: $!";
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116 91
117 # file contents now in $contents 92 # file contents now in $contents
118 print $contents; 93 print $contents;
119 94
120 # exit event loop and program 95 # exit event loop and program
121 Event::unloop; 96 EV::unloop;
122 }; 97 };
123 }; 98 };
124 99
125 # possibly queue up other requests, or open GUI windows, 100 # possibly queue up other requests, or open GUI windows,
126 # check for sockets etc. etc. 101 # check for sockets etc. etc.
127 102
128 # process events as long as there are some: 103 # process events as long as there are some:
129 Event::loop; 104 EV::loop;
130 105
131REQUEST ANATOMY AND LIFETIME 106REQUEST ANATOMY AND LIFETIME
132 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
133 not directly visible to Perl. 108 not directly visible to Perl.
134 109
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170 anymore (except possibly for the Perl object, but its connection to 145 anymore (except possibly for the Perl object, but its connection to
171 the actual aio request is severed and calling its methods will 146 the actual aio request is severed and calling its methods will
172 either do nothing or result in a runtime error). 147 either do nothing or result in a runtime error).
173 148
174FUNCTIONS 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
175 AIO REQUEST FUNCTIONS 217 AIO REQUEST FUNCTIONS
176 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
177 with the same name (sans "aio_"). The arguments are similar or 219 with the same name (sans "aio_"). The arguments are similar or
178 identical, and they all accept an additional (and optional) $callback 220 identical, and they all accept an additional (and optional) $callback
179 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
180 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
181 error, unlike perl, which usually delivers "false") as it's sole 223 error, unlike perl, which usually delivers "false") as its sole argument
182 argument when the given syscall has been executed asynchronously. 224 after the given syscall has been executed asynchronously.
183 225
184 All functions expecting a filehandle keep a copy of the filehandle 226 All functions expecting a filehandle keep a copy of the filehandle
185 internally until the request has finished. 227 internally until the request has finished.
186 228
187 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
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200 the user environment, d) use Glib::filename_from_unicode on unicode 242 the user environment, d) use Glib::filename_from_unicode on unicode
201 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
202 contents. 244 contents.
203 245
204 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
205 handles correctly wether it is set or not. 247 handles correctly whether it is set or not.
206 248
207 $prev_pri = aioreq_pri [$pri] 249 $prev_pri = aioreq_pri [$pri]
208 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
209 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.
210 252
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265 Asynchronously close a file and call the callback with the result 307 Asynchronously close a file and call the callback with the result
266 code. 308 code.
267 309
268 Unfortunately, you can't do this to perl. Perl *insists* very 310 Unfortunately, you can't do this to perl. Perl *insists* very
269 strongly on closing the file descriptor associated with the 311 strongly on closing the file descriptor associated with the
270 filehandle itself. Here is what aio_close will try: 312 filehandle itself.
271 313
272 1. dup()licate the fd 314 Therefore, "aio_close" will not close the filehandle - instead it
273 2. asynchronously close() the duplicated fd 315 will use dup2 to overwrite the file descriptor with the write-end of
274 3. dup()licate the fd once more 316 a pipe (the pipe fd will be created on demand and will be cached).
275 4. let perl close() the filehandle
276 5. asynchronously close the duplicated fd
277 317
278 The idea is that the first close() flushes stuff to disk that 318 Or in other words: the file descriptor will be closed, but it will
279 closing an fd will flush, so when perl closes the fd, nothing much 319 not be free for reuse until the perl filehandle is closed.
280 will need to be flushed. The second async. close() will then flush
281 stuff to disk that closing the last fd to the file will flush.
282
283 Just FYI, SuSv3 has this to say on close:
284
285 All outstanding record locks owned by the process on the file
286 associated with the file descriptor shall be removed.
287
288 If fildes refers to a socket, close() shall cause the socket to be
289 destroyed. ... close() shall block for up to the current linger
290 interval until all data is transmitted.
291 [this actually sounds like a specification bug, but who knows]
292
293 And at least Linux additionally actually flushes stuff on every
294 close, even when the file itself is still open.
295
296 Sounds enourmously inefficient and complicated? Yes... please show
297 me how to nuke perl's fd out of existence...
298 320
299 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 321 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
300 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 322 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
301 Reads or writes $length bytes from the specified $fh and $offset 323 Reads or writes $length bytes from or to the specified $fh and
302 into the scalar given by $data and offset $dataoffset and calls the 324 $offset into the scalar given by $data and offset $dataoffset and
303 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
304 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.
305 330
306 If $offset is undefined, then the current file descriptor offset 331 If $offset is undefined, then the current file descriptor offset
307 will be used (and updated), otherwise the file descriptor offset 332 will be used (and updated), otherwise the file descriptor offset
308 will not be changed by these calls. 333 will not be changed by these calls.
309 334
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332 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
333 with each other. 358 with each other.
334 359
335 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
336 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
337 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.
338 363
339 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",
340 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
341 regardless of the limitations of the operating system. 367 filehandle regardless of the limitations of the operating system.
342 368
343 Please note, however, that "aio_sendfile" can read more bytes from 369 Please note, however, that "aio_sendfile" can read more bytes from
344 $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
345 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 371 bytes have been read from "aio_sendfile" alone, as "aio_sendfile"
346 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
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381 aio_stat "/etc/passwd", sub { 407 aio_stat "/etc/passwd", sub {
382 $_[0] and die "stat failed: $!"; 408 $_[0] and die "stat failed: $!";
383 print "size is ", -s _, "\n"; 409 print "size is ", -s _, "\n";
384 }; 410 };
385 411
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
386 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 455 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
387 Works like perl's "utime" function (including the special case of 456 Works like perl's "utime" function (including the special case of
388 $atime and $mtime being undef). Fractional times are supported if 457 $atime and $mtime being undef). Fractional times are supported if
389 the underlying syscalls support them. 458 the underlying syscalls support them.
390 459
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460 aio_readdir $pathname, $callback->($entries) 529 aio_readdir $pathname, $callback->($entries)
461 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
462 entire directory (i.e. opendir + readdir + closedir). The entries 531 entire directory (i.e. opendir + readdir + closedir). The entries
463 will not be sorted, and will NOT include the "." and ".." entries. 532 will not be sorted, and will NOT include the "." and ".." entries.
464 533
465 The callback a single argument which is either "undef" or an 534 The callback is passed a single argument which is either "undef" or
466 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.
467 597
468 aio_load $path, $data, $callback->($status) 598 aio_load $path, $data, $callback->($status)
469 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
470 into memory. Status is the same as with aio_read. 600 into memory. Status is the same as with aio_read.
471 601
472 aio_copy $srcpath, $dstpath, $callback->($status) 602 aio_copy $srcpath, $dstpath, $callback->($status)
473 Try to copy the *file* (directories not supported as either source 603 Try to copy the *file* (directories not supported as either source
474 or destination) from $srcpath to $dstpath and call the callback with 604 or destination) from $srcpath to $dstpath and call the callback with
475 the 0 (error) or -1 ok. 605 a status of 0 (ok) or -1 (error, see $!).
476 606
477 This is a composite request that it creates the destination file 607 This is a composite request that creates the destination file with
478 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
479 using "aio_sendfile", followed by restoring atime, mtime, access 609 "aio_sendfile", followed by restoring atime, mtime, access mode and
480 mode and uid/gid, in that order. 610 uid/gid, in that order.
481 611
482 If an error occurs, the partial destination file will be unlinked, 612 If an error occurs, the partial destination file will be unlinked,
483 if possible, except when setting atime, mtime, access mode and 613 if possible, except when setting atime, mtime, access mode and
484 uid/gid, where errors are being ignored. 614 uid/gid, where errors are being ignored.
485 615
486 aio_move $srcpath, $dstpath, $callback->($status) 616 aio_move $srcpath, $dstpath, $callback->($status)
487 Try to move the *file* (directories not supported as either source 617 Try to move the *file* (directories not supported as either source
488 or destination) from $srcpath to $dstpath and call the callback with 618 or destination) from $srcpath to $dstpath and call the callback with
489 the 0 (error) or -1 ok. 619 a status of 0 (ok) or -1 (error, see $!).
490 620
491 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;
492 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"
493 and, if that is successful, unlinking the $srcpath. 623 and, if that is successful, unlinks the $srcpath.
494 624
495 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 625 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
496 Scans a directory (similar to "aio_readdir") but additionally tries 626 Scans a directory (similar to "aio_readdir") but additionally tries
497 to efficiently separate the entries of directory $path into two sets 627 to efficiently separate the entries of directory $path into two sets
498 of names, directories you can recurse into (directories), and ones 628 of names, directories you can recurse into (directories), and ones
… …
518 Implementation notes. 648 Implementation notes.
519 649
520 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry 650 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
521 can. 651 can.
522 652
653 If readdir returns file type information, then this is used directly
654 to find directories.
655
523 After reading the directory, the modification time, size etc. of the 656 Otherwise, after reading the directory, the modification time, size
524 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
525 (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
526 how many entries are directories (if >= 2). Otherwise, no knowledge 659 used to decide how many entries are directories (if >= 2).
527 of the number of subdirectories will be assumed. 660 Otherwise, no knowledge of the number of subdirectories will be
661 assumed.
528 662
529 Then entries will be sorted into likely directories (everything 663 Then entries will be sorted into likely directories a non-initial
530 without a non-initial dot currently) and likely non-directories 664 dot currently) and likely non-directories (see "aio_readdirx"). Then
531 (everything else). Then every entry plus an appended "/." will be 665 every entry plus an appended "/." will be "stat"'ed, likely
532 "stat"'ed, likely directories first. If that succeeds, it assumes 666 directories first, in order of their inode numbers. If that
533 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
534 be checked seperately). This is often faster than stat'ing the entry 668 directory (which will be checked seperately). This is often faster
535 itself because filesystems might detect the type of the entry 669 than stat'ing the entry itself because filesystems might detect the
536 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.
537 673
538 If the known number of directories (link count - 2) has been 674 If the known number of directories (link count - 2) has been
539 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.
540 676
541 This only works with certainty on POSIX (= UNIX) filesystems, which 677 This only works with certainty on POSIX (= UNIX) filesystems, which
… …
563 callback with the fdatasync result code. 699 callback with the fdatasync result code.
564 700
565 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
566 be detected, it will be emulated by calling "fsync" instead. 702 be detected, it will be emulated by calling "fsync" instead.
567 703
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
568 aio_pathsync $path, $callback->($status) 716 aio_pathsync $path, $callback->($status)
569 This request tries to open, fsync and close the given path. This is 717 This request tries to open, fsync and close the given path. This is
570 a composite request intended tosync directories after directory 718 a composite request intended to sync directories after directory
571 operations (E.g. rename). This might not work on all operating 719 operations (E.g. rename). This might not work on all operating
572 systems or have any specific effect, but usually it makes sure that 720 systems or have any specific effect, but usually it makes sure that
573 directory changes get written to disc. It works for anything that 721 directory changes get written to disc. It works for anything that
574 can be opened for read-only, not just directories. 722 can be opened for read-only, not just directories.
575 723
724 Future versions of this function might fall back to other methods
725 when "fsync" on the directory fails (such as calling "sync").
726
576 Passes 0 when everything went ok, and -1 on error. 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).
577 755
578 aio_group $callback->(...) 756 aio_group $callback->(...)
579 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
580 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
581 to bundle many requests into a single, composite, request with a 759 to bundle many requests into a single, composite, request with a
… …
624 802
625 cancel $req 803 cancel $req
626 Cancels the request, if possible. Has the effect of skipping 804 Cancels the request, if possible. Has the effect of skipping
627 execution when entering the execute state and skipping calling the 805 execution when entering the execute state and skipping calling the
628 callback when entering the the result state, but will leave the 806 callback when entering the the result state, but will leave the
629 request otherwise untouched. That means that requests that currently 807 request otherwise untouched (with the exception of readdir). That
630 execute will not be stopped and resources held by the request will 808 means that requests that currently execute will not be stopped and
631 not be freed prematurely. 809 resources held by the request will not be freed prematurely.
632 810
633 cb $req $callback->(...) 811 cb $req $callback->(...)
634 Replace (or simply set) the callback registered to the request. 812 Replace (or simply set) the callback registered to the request.
635 813
636 IO::AIO::GRP CLASS 814 IO::AIO::GRP CLASS
… …
679 Their lifetime, simplified, looks like this: when they are empty, they 857 Their lifetime, simplified, looks like this: when they are empty, they
680 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
681 "done" state, they will also finish. Otherwise they will continue to 859 "done" state, they will also finish. Otherwise they will continue to
682 exist. 860 exist.
683 861
684 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
685 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
686 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
687 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.
688 867
689 add $grp ... 868 add $grp ...
690 $grp->add (...) 869 $grp->add (...)
691 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
692 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
… …
696 875
697 $grp->cancel_subs 876 $grp->cancel_subs
698 Cancel all subrequests and clears any feeder, but not the group 877 Cancel all subrequests and clears any feeder, but not the group
699 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
700 result early. 879 result early.
880
881 The group request will finish normally (you cannot add requests to
882 the group).
701 883
702 $grp->result (...) 884 $grp->result (...)
703 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
704 when all subrequests have finished and set the groups errno to the 886 when all subrequests have finished and set the groups errno to the
705 current value of errno (just like calling "errno" without an error 887 current value of errno (just like calling "errno" without an error
… …
735 does not impose any limits). 917 does not impose any limits).
736 918
737 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
738 automatically removed from the group. 920 automatically removed from the group.
739 921
740 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.
741 924
742 Example: 925 Example:
743 926
744 # 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:
745 928
… …
756 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
757 whenever the group contains less than this many requests. 940 whenever the group contains less than this many requests.
758 941
759 Setting the limit to 0 will pause the feeding process. 942 Setting the limit to 0 will pause the feeding process.
760 943
944 The default value for the limit is 0, but note that setting a feeder
945 automatically bumps it up to 2.
946
761 SUPPORT FUNCTIONS 947 SUPPORT FUNCTIONS
762 EVENT PROCESSING AND EVENT LOOP INTEGRATION 948 EVENT PROCESSING AND EVENT LOOP INTEGRATION
763 $fileno = IO::AIO::poll_fileno 949 $fileno = IO::AIO::poll_fileno
764 Return the *request result pipe file descriptor*. This filehandle 950 Return the *request result pipe file descriptor*. This filehandle
765 must be polled for reading by some mechanism outside this module 951 must be polled for reading by some mechanism outside this module
766 (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
767 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.
768 955
769 See "poll_cb" for an example. 956 See "poll_cb" for an example.
770 957
771 IO::AIO::poll_cb 958 IO::AIO::poll_cb
772 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
773 this regularly. Returns the number of events processed. Returns 960 this regularly. Returns 0 if all events could be processed, or -1 if
774 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
775 processed depends on the settings of "IO::AIO::max_poll_req" and 963 the settings of "IO::AIO::max_poll_req" and
776 "IO::AIO::max_poll_time". 964 "IO::AIO::max_poll_time".
777 965
778 If not all requests were processed for whatever reason, the 966 If not all requests were processed for whatever reason, the
779 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.
780 969
781 Example: Install an Event watcher that automatically calls 970 Example: Install an Event watcher that automatically calls
782 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):
783 973
784 Event->io (fd => IO::AIO::poll_fileno, 974 Event->io (fd => IO::AIO::poll_fileno,
785 poll => 'r', async => 1, 975 poll => 'r', async => 1,
786 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;
787 1001
788 IO::AIO::max_poll_reqs $nreqs 1002 IO::AIO::max_poll_reqs $nreqs
789 IO::AIO::max_poll_time $seconds 1003 IO::AIO::max_poll_time $seconds
790 These set the maximum number of requests (default 0, meaning 1004 These set the maximum number of requests (default 0, meaning
791 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
… …
815 # use a low priority so other tasks have priority 1029 # use a low priority so other tasks have priority
816 Event->io (fd => IO::AIO::poll_fileno, 1030 Event->io (fd => IO::AIO::poll_fileno,
817 poll => 'r', nice => 1, 1031 poll => 'r', nice => 1,
818 cb => &IO::AIO::poll_cb); 1032 cb => &IO::AIO::poll_cb);
819 1033
820 IO::AIO::poll_wait
821 If there are any outstanding requests and none of them in the result
822 phase, wait till the result filehandle becomes ready for reading
823 (simply does a "select" on the filehandle. This is useful if you
824 want to synchronously wait for some requests to finish).
825
826 See "nreqs" for an example.
827
828 IO::AIO::poll
829 Waits until some requests have been handled.
830
831 Returns the number of requests processed, but is otherwise strictly
832 equivalent to:
833
834 IO::AIO::poll_wait, IO::AIO::poll_cb
835
836 IO::AIO::flush
837 Wait till all outstanding AIO requests have been handled.
838
839 Strictly equivalent to:
840
841 IO::AIO::poll_wait, IO::AIO::poll_cb
842 while IO::AIO::nreqs;
843
844 CONTROLLING THE NUMBER OF THREADS 1034 CONTROLLING THE NUMBER OF THREADS
845 IO::AIO::min_parallel $nthreads 1035 IO::AIO::min_parallel $nthreads
846 Set the minimum number of AIO threads to $nthreads. The current 1036 Set the minimum number of AIO threads to $nthreads. The current
847 default is 8, which means eight asynchronous operations can execute 1037 default is 8, which means eight asynchronous operations can execute
848 concurrently at any one time (the number of outstanding requests, 1038 concurrently at any one time (the number of outstanding requests,
… …
890 1080
891 The default is probably ok in most situations, especially if thread 1081 The default is probably ok in most situations, especially if thread
892 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
893 might want to use larger values. 1083 might want to use larger values.
894 1084
895 $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1085 IO::AIO::max_outstanding $maxreqs
896 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
897 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
898 inexact: Better use an "aio_group" together with a feed callback. 1088 inexact: Better use an "aio_group" together with a feed callback.
899 1089
900 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
… …
904 1094
905 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
906 the number of outstanding requests. 1096 the number of outstanding requests.
907 1097
908 You can still queue as many requests as you want. Therefore, 1098 You can still queue as many requests as you want. Therefore,
909 "max_oustsanding" is mainly useful in simple scripts (with low 1099 "max_outstanding" is mainly useful in simple scripts (with low
910 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
911 (with large values). 1101 (with large values).
912 1102
913 STATISTICAL INFORMATION 1103 STATISTICAL INFORMATION
914 IO::AIO::nreqs 1104 IO::AIO::nreqs
… …
926 executed). 1116 executed).
927 1117
928 IO::AIO::npending 1118 IO::AIO::npending
929 Returns the number of requests currently in the pending state 1119 Returns the number of requests currently in the pending state
930 (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);
931 1239
932 FORK BEHAVIOUR 1240 FORK BEHAVIOUR
933 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:
934 1242
935 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
… …
964 1272
965KNOWN BUGS 1273KNOWN BUGS
966 Known bugs will be fixed in the next release. 1274 Known bugs will be fixed in the next release.
967 1275
968SEE ALSO 1276SEE ALSO
969 Coro::AIO. 1277 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1278 more natural syntax.
970 1279
971AUTHOR 1280AUTHOR
972 Marc Lehmann <schmorp@schmorp.de> 1281 Marc Lehmann <schmorp@schmorp.de>
973 http://home.schmorp.de/ 1282 http://home.schmorp.de/
974 1283

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