1 |
=head1 NAME |
2 |
|
3 |
IO::AIO - Asynchronous Input/Output |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
7 |
use IO::AIO; |
8 |
|
9 |
aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
10 |
my $fh = shift |
11 |
or die "/etc/passwd: $!"; |
12 |
... |
13 |
}; |
14 |
|
15 |
aio_unlink "/tmp/file", sub { }; |
16 |
|
17 |
aio_read $fh, 30000, 1024, $buffer, 0, sub { |
18 |
$_[0] > 0 or die "read error: $!"; |
19 |
}; |
20 |
|
21 |
# version 2+ has request and group objects |
22 |
use IO::AIO 2; |
23 |
|
24 |
aioreq_pri 4; # give next request a very high priority |
25 |
my $req = aio_unlink "/tmp/file", sub { }; |
26 |
$req->cancel; # cancel request if still in queue |
27 |
|
28 |
my $grp = aio_group sub { print "all stats done\n" }; |
29 |
add $grp aio_stat "..." for ...; |
30 |
|
31 |
=head1 DESCRIPTION |
32 |
|
33 |
This module implements asynchronous I/O using whatever means your |
34 |
operating system supports. It is implemented as an interface to C<libeio> |
35 |
(L<http://software.schmorp.de/pkg/libeio.html>). |
36 |
|
37 |
Asynchronous means that operations that can normally block your program |
38 |
(e.g. reading from disk) will be done asynchronously: the operation |
39 |
will still block, but you can do something else in the meantime. This |
40 |
is extremely useful for programs that need to stay interactive even |
41 |
when doing heavy I/O (GUI programs, high performance network servers |
42 |
etc.), but can also be used to easily do operations in parallel that are |
43 |
normally done sequentially, e.g. stat'ing many files, which is much faster |
44 |
on a RAID volume or over NFS when you do a number of stat operations |
45 |
concurrently. |
46 |
|
47 |
While most of this works on all types of file descriptors (for |
48 |
example sockets), using these functions on file descriptors that |
49 |
support nonblocking operation (again, sockets, pipes etc.) is |
50 |
very inefficient. Use an event loop for that (such as the L<EV> |
51 |
module): IO::AIO will naturally fit into such an event loop itself. |
52 |
|
53 |
In this version, a number of threads are started that execute your |
54 |
requests and signal their completion. You don't need thread support |
55 |
in perl, and the threads created by this module will not be visible |
56 |
to perl. In the future, this module might make use of the native aio |
57 |
functions available on many operating systems. However, they are often |
58 |
not well-supported or restricted (GNU/Linux doesn't allow them on normal |
59 |
files currently, for example), and they would only support aio_read and |
60 |
aio_write, so the remaining functionality would have to be implemented |
61 |
using threads anyway. |
62 |
|
63 |
Although the module will work in the presence of other (Perl-) threads, |
64 |
it is currently not reentrant in any way, so use appropriate locking |
65 |
yourself, always call C<poll_cb> from within the same thread, or never |
66 |
call C<poll_cb> (or other C<aio_> functions) recursively. |
67 |
|
68 |
=head2 EXAMPLE |
69 |
|
70 |
This is a simple example that uses the EV module and loads |
71 |
F</etc/passwd> asynchronously: |
72 |
|
73 |
use Fcntl; |
74 |
use EV; |
75 |
use IO::AIO; |
76 |
|
77 |
# register the IO::AIO callback with EV |
78 |
my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
79 |
|
80 |
# queue the request to open /etc/passwd |
81 |
aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
82 |
my $fh = shift |
83 |
or die "error while opening: $!"; |
84 |
|
85 |
# stat'ing filehandles is generally non-blocking |
86 |
my $size = -s $fh; |
87 |
|
88 |
# queue a request to read the file |
89 |
my $contents; |
90 |
aio_read $fh, 0, $size, $contents, 0, sub { |
91 |
$_[0] == $size |
92 |
or die "short read: $!"; |
93 |
|
94 |
close $fh; |
95 |
|
96 |
# file contents now in $contents |
97 |
print $contents; |
98 |
|
99 |
# exit event loop and program |
100 |
EV::unloop; |
101 |
}; |
102 |
}; |
103 |
|
104 |
# possibly queue up other requests, or open GUI windows, |
105 |
# check for sockets etc. etc. |
106 |
|
107 |
# process events as long as there are some: |
108 |
EV::loop; |
109 |
|
110 |
=head1 REQUEST ANATOMY AND LIFETIME |
111 |
|
112 |
Every C<aio_*> function creates a request. which is a C data structure not |
113 |
directly visible to Perl. |
114 |
|
115 |
If called in non-void context, every request function returns a Perl |
116 |
object representing the request. In void context, nothing is returned, |
117 |
which saves a bit of memory. |
118 |
|
119 |
The perl object is a fairly standard ref-to-hash object. The hash contents |
120 |
are not used by IO::AIO so you are free to store anything you like in it. |
121 |
|
122 |
During their existance, aio requests travel through the following states, |
123 |
in order: |
124 |
|
125 |
=over 4 |
126 |
|
127 |
=item ready |
128 |
|
129 |
Immediately after a request is created it is put into the ready state, |
130 |
waiting for a thread to execute it. |
131 |
|
132 |
=item execute |
133 |
|
134 |
A thread has accepted the request for processing and is currently |
135 |
executing it (e.g. blocking in read). |
136 |
|
137 |
=item pending |
138 |
|
139 |
The request has been executed and is waiting for result processing. |
140 |
|
141 |
While request submission and execution is fully asynchronous, result |
142 |
processing is not and relies on the perl interpreter calling C<poll_cb> |
143 |
(or another function with the same effect). |
144 |
|
145 |
=item result |
146 |
|
147 |
The request results are processed synchronously by C<poll_cb>. |
148 |
|
149 |
The C<poll_cb> function will process all outstanding aio requests by |
150 |
calling their callbacks, freeing memory associated with them and managing |
151 |
any groups they are contained in. |
152 |
|
153 |
=item done |
154 |
|
155 |
Request has reached the end of its lifetime and holds no resources anymore |
156 |
(except possibly for the Perl object, but its connection to the actual |
157 |
aio request is severed and calling its methods will either do nothing or |
158 |
result in a runtime error). |
159 |
|
160 |
=back |
161 |
|
162 |
=cut |
163 |
|
164 |
package IO::AIO; |
165 |
|
166 |
use Carp (); |
167 |
|
168 |
use common::sense; |
169 |
|
170 |
use base 'Exporter'; |
171 |
|
172 |
BEGIN { |
173 |
our $VERSION = '4.0'; |
174 |
|
175 |
our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close |
176 |
aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx |
177 |
aio_scandir aio_symlink aio_readlink aio_realpath aio_sync |
178 |
aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate |
179 |
aio_pathsync aio_readahead |
180 |
aio_rename aio_link aio_move aio_copy aio_group |
181 |
aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown |
182 |
aio_chmod aio_utime aio_truncate |
183 |
aio_msync aio_mtouch aio_mlock aio_mlockall |
184 |
aio_statvfs); |
185 |
|
186 |
our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
187 |
our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
188 |
min_parallel max_parallel max_idle idle_timeout |
189 |
nreqs nready npending nthreads |
190 |
max_poll_time max_poll_reqs |
191 |
sendfile fadvise madvise |
192 |
mmap munmap munlock munlockall); |
193 |
|
194 |
push @AIO_REQ, qw(aio_busy); # not exported |
195 |
|
196 |
@IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
197 |
|
198 |
require XSLoader; |
199 |
XSLoader::load ("IO::AIO", $VERSION); |
200 |
} |
201 |
|
202 |
=head1 FUNCTIONS |
203 |
|
204 |
=head2 QUICK OVERVIEW |
205 |
|
206 |
This section simply lists the prototypes of the most important functions |
207 |
for quick reference. See the following sections for function-by-function |
208 |
documentation. |
209 |
|
210 |
aio_open $pathname, $flags, $mode, $callback->($fh) |
211 |
aio_close $fh, $callback->($status) |
212 |
aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
213 |
aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
214 |
aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
215 |
aio_readahead $fh,$offset,$length, $callback->($retval) |
216 |
aio_stat $fh_or_path, $callback->($status) |
217 |
aio_lstat $fh, $callback->($status) |
218 |
aio_statvfs $fh_or_path, $callback->($statvfs) |
219 |
aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
220 |
aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
221 |
aio_truncate $fh_or_path, $offset, $callback->($status) |
222 |
aio_chmod $fh_or_path, $mode, $callback->($status) |
223 |
aio_unlink $pathname, $callback->($status) |
224 |
aio_mknod $path, $mode, $dev, $callback->($status) |
225 |
aio_link $srcpath, $dstpath, $callback->($status) |
226 |
aio_symlink $srcpath, $dstpath, $callback->($status) |
227 |
aio_readlink $path, $callback->($link) |
228 |
aio_realpath $path, $callback->($link) |
229 |
aio_rename $srcpath, $dstpath, $callback->($status) |
230 |
aio_mkdir $pathname, $mode, $callback->($status) |
231 |
aio_rmdir $pathname, $callback->($status) |
232 |
aio_readdir $pathname, $callback->($entries) |
233 |
aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
234 |
IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST |
235 |
IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN |
236 |
aio_load $path, $data, $callback->($status) |
237 |
aio_copy $srcpath, $dstpath, $callback->($status) |
238 |
aio_move $srcpath, $dstpath, $callback->($status) |
239 |
aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
240 |
aio_rmtree $path, $callback->($status) |
241 |
aio_sync $callback->($status) |
242 |
aio_syncfs $fh, $callback->($status) |
243 |
aio_fsync $fh, $callback->($status) |
244 |
aio_fdatasync $fh, $callback->($status) |
245 |
aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
246 |
aio_pathsync $path, $callback->($status) |
247 |
aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
248 |
aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
249 |
aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
250 |
aio_mlockall $flags, $callback->($status) |
251 |
aio_group $callback->(...) |
252 |
aio_nop $callback->() |
253 |
|
254 |
$prev_pri = aioreq_pri [$pri] |
255 |
aioreq_nice $pri_adjust |
256 |
|
257 |
IO::AIO::poll_wait |
258 |
IO::AIO::poll_cb |
259 |
IO::AIO::poll |
260 |
IO::AIO::flush |
261 |
IO::AIO::max_poll_reqs $nreqs |
262 |
IO::AIO::max_poll_time $seconds |
263 |
IO::AIO::min_parallel $nthreads |
264 |
IO::AIO::max_parallel $nthreads |
265 |
IO::AIO::max_idle $nthreads |
266 |
IO::AIO::idle_timeout $seconds |
267 |
IO::AIO::max_outstanding $maxreqs |
268 |
IO::AIO::nreqs |
269 |
IO::AIO::nready |
270 |
IO::AIO::npending |
271 |
|
272 |
IO::AIO::sendfile $ofh, $ifh, $offset, $count |
273 |
IO::AIO::fadvise $fh, $offset, $len, $advice |
274 |
IO::AIO::madvise $scalar, $offset, $length, $advice |
275 |
IO::AIO::mprotect $scalar, $offset, $length, $protect |
276 |
IO::AIO::munlock $scalar, $offset = 0, $length = undef |
277 |
IO::AIO::munlockall |
278 |
|
279 |
=head2 AIO REQUEST FUNCTIONS |
280 |
|
281 |
All the C<aio_*> calls are more or less thin wrappers around the syscall |
282 |
with the same name (sans C<aio_>). The arguments are similar or identical, |
283 |
and they all accept an additional (and optional) C<$callback> argument |
284 |
which must be a code reference. This code reference will get called with |
285 |
the syscall return code (e.g. most syscalls return C<-1> on error, unlike |
286 |
perl, which usually delivers "false") as its sole argument after the given |
287 |
syscall has been executed asynchronously. |
288 |
|
289 |
All functions expecting a filehandle keep a copy of the filehandle |
290 |
internally until the request has finished. |
291 |
|
292 |
All functions return request objects of type L<IO::AIO::REQ> that allow |
293 |
further manipulation of those requests while they are in-flight. |
294 |
|
295 |
The pathnames you pass to these routines I<must> be absolute and |
296 |
encoded as octets. The reason for the former is that at the time the |
297 |
request is being executed, the current working directory could have |
298 |
changed. Alternatively, you can make sure that you never change the |
299 |
current working directory anywhere in the program and then use relative |
300 |
paths. |
301 |
|
302 |
To encode pathnames as octets, either make sure you either: a) always pass |
303 |
in filenames you got from outside (command line, readdir etc.) without |
304 |
tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode |
305 |
your pathnames to the locale (or other) encoding in effect in the user |
306 |
environment, d) use Glib::filename_from_unicode on unicode filenames or e) |
307 |
use something else to ensure your scalar has the correct contents. |
308 |
|
309 |
This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
310 |
handles correctly whether it is set or not. |
311 |
|
312 |
=over 4 |
313 |
|
314 |
=item $prev_pri = aioreq_pri [$pri] |
315 |
|
316 |
Returns the priority value that would be used for the next request and, if |
317 |
C<$pri> is given, sets the priority for the next aio request. |
318 |
|
319 |
The default priority is C<0>, the minimum and maximum priorities are C<-4> |
320 |
and C<4>, respectively. Requests with higher priority will be serviced |
321 |
first. |
322 |
|
323 |
The priority will be reset to C<0> after each call to one of the C<aio_*> |
324 |
functions. |
325 |
|
326 |
Example: open a file with low priority, then read something from it with |
327 |
higher priority so the read request is serviced before other low priority |
328 |
open requests (potentially spamming the cache): |
329 |
|
330 |
aioreq_pri -3; |
331 |
aio_open ..., sub { |
332 |
return unless $_[0]; |
333 |
|
334 |
aioreq_pri -2; |
335 |
aio_read $_[0], ..., sub { |
336 |
... |
337 |
}; |
338 |
}; |
339 |
|
340 |
|
341 |
=item aioreq_nice $pri_adjust |
342 |
|
343 |
Similar to C<aioreq_pri>, but subtracts the given value from the current |
344 |
priority, so the effect is cumulative. |
345 |
|
346 |
|
347 |
=item aio_open $pathname, $flags, $mode, $callback->($fh) |
348 |
|
349 |
Asynchronously open or create a file and call the callback with a newly |
350 |
created filehandle for the file. |
351 |
|
352 |
The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
353 |
for an explanation. |
354 |
|
355 |
The C<$flags> argument is a bitmask. See the C<Fcntl> module for a |
356 |
list. They are the same as used by C<sysopen>. |
357 |
|
358 |
Likewise, C<$mode> specifies the mode of the newly created file, if it |
359 |
didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, |
360 |
except that it is mandatory (i.e. use C<0> if you don't create new files, |
361 |
and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified |
362 |
by the umask in effect then the request is being executed, so better never |
363 |
change the umask. |
364 |
|
365 |
Example: |
366 |
|
367 |
aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
368 |
if ($_[0]) { |
369 |
print "open successful, fh is $_[0]\n"; |
370 |
... |
371 |
} else { |
372 |
die "open failed: $!\n"; |
373 |
} |
374 |
}; |
375 |
|
376 |
In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>, |
377 |
C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the |
378 |
following POSIX and non-POSIX constants are available (missing ones on |
379 |
your system are, as usual, C<0>): |
380 |
|
381 |
C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>, |
382 |
C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>, |
383 |
C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>. |
384 |
|
385 |
|
386 |
=item aio_close $fh, $callback->($status) |
387 |
|
388 |
Asynchronously close a file and call the callback with the result |
389 |
code. |
390 |
|
391 |
Unfortunately, you can't do this to perl. Perl I<insists> very strongly on |
392 |
closing the file descriptor associated with the filehandle itself. |
393 |
|
394 |
Therefore, C<aio_close> will not close the filehandle - instead it will |
395 |
use dup2 to overwrite the file descriptor with the write-end of a pipe |
396 |
(the pipe fd will be created on demand and will be cached). |
397 |
|
398 |
Or in other words: the file descriptor will be closed, but it will not be |
399 |
free for reuse until the perl filehandle is closed. |
400 |
|
401 |
=cut |
402 |
|
403 |
=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
404 |
|
405 |
=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
406 |
|
407 |
Reads or writes C<$length> bytes from or to the specified C<$fh> and |
408 |
C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> |
409 |
and calls the callback without the actual number of bytes read (or -1 on |
410 |
error, just like the syscall). |
411 |
|
412 |
C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to |
413 |
offset plus the actual number of bytes read. |
414 |
|
415 |
If C<$offset> is undefined, then the current file descriptor offset will |
416 |
be used (and updated), otherwise the file descriptor offset will not be |
417 |
changed by these calls. |
418 |
|
419 |
If C<$length> is undefined in C<aio_write>, use the remaining length of |
420 |
C<$data>. |
421 |
|
422 |
If C<$dataoffset> is less than zero, it will be counted from the end of |
423 |
C<$data>. |
424 |
|
425 |
The C<$data> scalar I<MUST NOT> be modified in any way while the request |
426 |
is outstanding. Modifying it can result in segfaults or World War III (if |
427 |
the necessary/optional hardware is installed). |
428 |
|
429 |
Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
430 |
offset C<0> within the scalar: |
431 |
|
432 |
aio_read $fh, 7, 15, $buffer, 0, sub { |
433 |
$_[0] > 0 or die "read error: $!"; |
434 |
print "read $_[0] bytes: <$buffer>\n"; |
435 |
}; |
436 |
|
437 |
|
438 |
=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
439 |
|
440 |
Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts |
441 |
reading at byte offset C<$in_offset>, and starts writing at the current |
442 |
file offset of C<$out_fh>. Because of that, it is not safe to issue more |
443 |
than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each |
444 |
other. The same C<$in_fh> works fine though, as this function does not |
445 |
move or use the file offset of C<$in_fh>. |
446 |
|
447 |
Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than |
448 |
are written, and there is no way to find out how many more bytes have been |
449 |
read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the |
450 |
number of bytes written to C<$out_fh>. Only if the result value equals |
451 |
C<$length> one can assume that C<$length> bytes have been read. |
452 |
|
453 |
Unlike with other C<aio_> functions, it makes a lot of sense to use |
454 |
C<aio_sendfile> on non-blocking sockets, as long as one end (typically |
455 |
the C<$in_fh>) is a file - the file I/O will then be asynchronous, while |
456 |
the socket I/O will be non-blocking. Note, however, that you can run |
457 |
into a trap where C<aio_sendfile> reads some data with readahead, then |
458 |
fails to write all data, and when the socket is ready the next time, the |
459 |
data in the cache is already lost, forcing C<aio_sendfile> to again hit |
460 |
the disk. Explicit C<aio_read> + C<aio_write> let's you better control |
461 |
resource usage. |
462 |
|
463 |
This call tries to make use of a native C<sendfile>-like syscall to |
464 |
provide zero-copy operation. For this to work, C<$out_fh> should refer to |
465 |
a socket, and C<$in_fh> should refer to an mmap'able file. |
466 |
|
467 |
If a native sendfile cannot be found or it fails with C<ENOSYS>, |
468 |
C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or |
469 |
C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any |
470 |
type of filehandle regardless of the limitations of the operating system. |
471 |
|
472 |
As native sendfile syscalls (as practically any non-POSIX interface hacked |
473 |
together in a hurry to improve benchmark numbers) tend to be rather buggy |
474 |
on many systems, this implementation tries to work around some known bugs |
475 |
in Linux and FreeBSD kernels (probably others, too), but that might fail, |
476 |
so you really really should check the return value of C<aio_sendfile> - |
477 |
fewre bytes than expected might have been transferred. |
478 |
|
479 |
|
480 |
=item aio_readahead $fh,$offset,$length, $callback->($retval) |
481 |
|
482 |
C<aio_readahead> populates the page cache with data from a file so that |
483 |
subsequent reads from that file will not block on disk I/O. The C<$offset> |
484 |
argument specifies the starting point from which data is to be read and |
485 |
C<$length> specifies the number of bytes to be read. I/O is performed in |
486 |
whole pages, so that offset is effectively rounded down to a page boundary |
487 |
and bytes are read up to the next page boundary greater than or equal to |
488 |
(off-set+length). C<aio_readahead> does not read beyond the end of the |
489 |
file. The current file offset of the file is left unchanged. |
490 |
|
491 |
If that syscall doesn't exist (likely if your OS isn't Linux) it will be |
492 |
emulated by simply reading the data, which would have a similar effect. |
493 |
|
494 |
|
495 |
=item aio_stat $fh_or_path, $callback->($status) |
496 |
|
497 |
=item aio_lstat $fh, $callback->($status) |
498 |
|
499 |
Works like perl's C<stat> or C<lstat> in void context. The callback will |
500 |
be called after the stat and the results will be available using C<stat _> |
501 |
or C<-s _> etc... |
502 |
|
503 |
The pathname passed to C<aio_stat> must be absolute. See API NOTES, above, |
504 |
for an explanation. |
505 |
|
506 |
Currently, the stats are always 64-bit-stats, i.e. instead of returning an |
507 |
error when stat'ing a large file, the results will be silently truncated |
508 |
unless perl itself is compiled with large file support. |
509 |
|
510 |
To help interpret the mode and dev/rdev stat values, IO::AIO offers the |
511 |
following constants and functions (if not implemented, the constants will |
512 |
be C<0> and the functions will either C<croak> or fall back on traditional |
513 |
behaviour). |
514 |
|
515 |
C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>, |
516 |
C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>, |
517 |
C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>. |
518 |
|
519 |
Example: Print the length of F</etc/passwd>: |
520 |
|
521 |
aio_stat "/etc/passwd", sub { |
522 |
$_[0] and die "stat failed: $!"; |
523 |
print "size is ", -s _, "\n"; |
524 |
}; |
525 |
|
526 |
|
527 |
=item aio_statvfs $fh_or_path, $callback->($statvfs) |
528 |
|
529 |
Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on |
530 |
whether a file handle or path was passed. |
531 |
|
532 |
On success, the callback is passed a hash reference with the following |
533 |
members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>, |
534 |
C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef> |
535 |
is passed. |
536 |
|
537 |
The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and |
538 |
C<ST_NOSUID>. |
539 |
|
540 |
The following non-POSIX IO::AIO::ST_* flag masks are defined to |
541 |
their correct value when available, or to C<0> on systems that do |
542 |
not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>, |
543 |
C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>, |
544 |
C<ST_NODIRATIME> and C<ST_RELATIME>. |
545 |
|
546 |
Example: stat C</wd> and dump out the data if successful. |
547 |
|
548 |
aio_statvfs "/wd", sub { |
549 |
my $f = $_[0] |
550 |
or die "statvfs: $!"; |
551 |
|
552 |
use Data::Dumper; |
553 |
say Dumper $f; |
554 |
}; |
555 |
|
556 |
# result: |
557 |
{ |
558 |
bsize => 1024, |
559 |
bfree => 4333064312, |
560 |
blocks => 10253828096, |
561 |
files => 2050765568, |
562 |
flag => 4096, |
563 |
favail => 2042092649, |
564 |
bavail => 4333064312, |
565 |
ffree => 2042092649, |
566 |
namemax => 255, |
567 |
frsize => 1024, |
568 |
fsid => 1810 |
569 |
} |
570 |
|
571 |
|
572 |
=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
573 |
|
574 |
Works like perl's C<utime> function (including the special case of $atime |
575 |
and $mtime being undef). Fractional times are supported if the underlying |
576 |
syscalls support them. |
577 |
|
578 |
When called with a pathname, uses utimes(2) if available, otherwise |
579 |
utime(2). If called on a file descriptor, uses futimes(2) if available, |
580 |
otherwise returns ENOSYS, so this is not portable. |
581 |
|
582 |
Examples: |
583 |
|
584 |
# set atime and mtime to current time (basically touch(1)): |
585 |
aio_utime "path", undef, undef; |
586 |
# set atime to current time and mtime to beginning of the epoch: |
587 |
aio_utime "path", time, undef; # undef==0 |
588 |
|
589 |
|
590 |
=item aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
591 |
|
592 |
Works like perl's C<chown> function, except that C<undef> for either $uid |
593 |
or $gid is being interpreted as "do not change" (but -1 can also be used). |
594 |
|
595 |
Examples: |
596 |
|
597 |
# same as "chown root path" in the shell: |
598 |
aio_chown "path", 0, -1; |
599 |
# same as above: |
600 |
aio_chown "path", 0, undef; |
601 |
|
602 |
|
603 |
=item aio_truncate $fh_or_path, $offset, $callback->($status) |
604 |
|
605 |
Works like truncate(2) or ftruncate(2). |
606 |
|
607 |
|
608 |
=item aio_chmod $fh_or_path, $mode, $callback->($status) |
609 |
|
610 |
Works like perl's C<chmod> function. |
611 |
|
612 |
|
613 |
=item aio_unlink $pathname, $callback->($status) |
614 |
|
615 |
Asynchronously unlink (delete) a file and call the callback with the |
616 |
result code. |
617 |
|
618 |
|
619 |
=item aio_mknod $path, $mode, $dev, $callback->($status) |
620 |
|
621 |
[EXPERIMENTAL] |
622 |
|
623 |
Asynchronously create a device node (or fifo). See mknod(2). |
624 |
|
625 |
The only (POSIX-) portable way of calling this function is: |
626 |
|
627 |
aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
628 |
|
629 |
See C<aio_stat> for info about some potentially helpful extra constants |
630 |
and functions. |
631 |
|
632 |
=item aio_link $srcpath, $dstpath, $callback->($status) |
633 |
|
634 |
Asynchronously create a new link to the existing object at C<$srcpath> at |
635 |
the path C<$dstpath> and call the callback with the result code. |
636 |
|
637 |
|
638 |
=item aio_symlink $srcpath, $dstpath, $callback->($status) |
639 |
|
640 |
Asynchronously create a new symbolic link to the existing object at C<$srcpath> at |
641 |
the path C<$dstpath> and call the callback with the result code. |
642 |
|
643 |
|
644 |
=item aio_readlink $path, $callback->($link) |
645 |
|
646 |
Asynchronously read the symlink specified by C<$path> and pass it to |
647 |
the callback. If an error occurs, nothing or undef gets passed to the |
648 |
callback. |
649 |
|
650 |
|
651 |
=item aio_realpath $path, $callback->($path) |
652 |
|
653 |
Asynchronously make the path absolute and resolve any symlinks in |
654 |
C<$path>. The resulting path only consists of directories (Same as |
655 |
L<Cwd::realpath>). |
656 |
|
657 |
This request can be used to get the absolute path of the current working |
658 |
directory by passing it a path of F<.> (a single dot). |
659 |
|
660 |
|
661 |
=item aio_rename $srcpath, $dstpath, $callback->($status) |
662 |
|
663 |
Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as |
664 |
rename(2) and call the callback with the result code. |
665 |
|
666 |
|
667 |
=item aio_mkdir $pathname, $mode, $callback->($status) |
668 |
|
669 |
Asynchronously mkdir (create) a directory and call the callback with |
670 |
the result code. C<$mode> will be modified by the umask at the time the |
671 |
request is executed, so do not change your umask. |
672 |
|
673 |
|
674 |
=item aio_rmdir $pathname, $callback->($status) |
675 |
|
676 |
Asynchronously rmdir (delete) a directory and call the callback with the |
677 |
result code. |
678 |
|
679 |
|
680 |
=item aio_readdir $pathname, $callback->($entries) |
681 |
|
682 |
Unlike the POSIX call of the same name, C<aio_readdir> reads an entire |
683 |
directory (i.e. opendir + readdir + closedir). The entries will not be |
684 |
sorted, and will B<NOT> include the C<.> and C<..> entries. |
685 |
|
686 |
The callback is passed a single argument which is either C<undef> or an |
687 |
array-ref with the filenames. |
688 |
|
689 |
|
690 |
=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
691 |
|
692 |
Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to |
693 |
tune behaviour and output format. In case of an error, C<$entries> will be |
694 |
C<undef>. |
695 |
|
696 |
The flags are a combination of the following constants, ORed together (the |
697 |
flags will also be passed to the callback, possibly modified): |
698 |
|
699 |
=over 4 |
700 |
|
701 |
=item IO::AIO::READDIR_DENTS |
702 |
|
703 |
When this flag is off, then the callback gets an arrayref consisting of |
704 |
names only (as with C<aio_readdir>), otherwise it gets an arrayref with |
705 |
C<[$name, $type, $inode]> arrayrefs, each describing a single directory |
706 |
entry in more detail. |
707 |
|
708 |
C<$name> is the name of the entry. |
709 |
|
710 |
C<$type> is one of the C<IO::AIO::DT_xxx> constants: |
711 |
|
712 |
C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>, |
713 |
C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>, |
714 |
C<IO::AIO::DT_WHT>. |
715 |
|
716 |
C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to |
717 |
know, you have to run stat yourself. Also, for speed reasons, the C<$type> |
718 |
scalars are read-only: you can not modify them. |
719 |
|
720 |
C<$inode> is the inode number (which might not be exact on systems with 64 |
721 |
bit inode numbers and 32 bit perls). This field has unspecified content on |
722 |
systems that do not deliver the inode information. |
723 |
|
724 |
=item IO::AIO::READDIR_DIRS_FIRST |
725 |
|
726 |
When this flag is set, then the names will be returned in an order where |
727 |
likely directories come first, in optimal stat order. This is useful when |
728 |
you need to quickly find directories, or you want to find all directories |
729 |
while avoiding to stat() each entry. |
730 |
|
731 |
If the system returns type information in readdir, then this is used |
732 |
to find directories directly. Otherwise, likely directories are names |
733 |
beginning with ".", or otherwise names with no dots, of which names with |
734 |
short names are tried first. |
735 |
|
736 |
=item IO::AIO::READDIR_STAT_ORDER |
737 |
|
738 |
When this flag is set, then the names will be returned in an order |
739 |
suitable for stat()'ing each one. That is, when you plan to stat() |
740 |
all files in the given directory, then the returned order will likely |
741 |
be fastest. |
742 |
|
743 |
If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then |
744 |
the likely dirs come first, resulting in a less optimal stat order. |
745 |
|
746 |
=item IO::AIO::READDIR_FOUND_UNKNOWN |
747 |
|
748 |
This flag should not be set when calling C<aio_readdirx>. Instead, it |
749 |
is being set by C<aio_readdirx>, when any of the C<$type>'s found were |
750 |
C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all |
751 |
C<$type>'s are known, which can be used to speed up some algorithms. |
752 |
|
753 |
=back |
754 |
|
755 |
|
756 |
=item aio_load $path, $data, $callback->($status) |
757 |
|
758 |
This is a composite request that tries to fully load the given file into |
759 |
memory. Status is the same as with aio_read. |
760 |
|
761 |
=cut |
762 |
|
763 |
sub aio_load($$;$) { |
764 |
my ($path, undef, $cb) = @_; |
765 |
my $data = \$_[1]; |
766 |
|
767 |
my $pri = aioreq_pri; |
768 |
my $grp = aio_group $cb; |
769 |
|
770 |
aioreq_pri $pri; |
771 |
add $grp aio_open $path, O_RDONLY, 0, sub { |
772 |
my $fh = shift |
773 |
or return $grp->result (-1); |
774 |
|
775 |
aioreq_pri $pri; |
776 |
add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub { |
777 |
$grp->result ($_[0]); |
778 |
}; |
779 |
}; |
780 |
|
781 |
$grp |
782 |
} |
783 |
|
784 |
=item aio_copy $srcpath, $dstpath, $callback->($status) |
785 |
|
786 |
Try to copy the I<file> (directories not supported as either source or |
787 |
destination) from C<$srcpath> to C<$dstpath> and call the callback with |
788 |
a status of C<0> (ok) or C<-1> (error, see C<$!>). |
789 |
|
790 |
This is a composite request that creates the destination file with |
791 |
mode 0200 and copies the contents of the source file into it using |
792 |
C<aio_sendfile>, followed by restoring atime, mtime, access mode and |
793 |
uid/gid, in that order. |
794 |
|
795 |
If an error occurs, the partial destination file will be unlinked, if |
796 |
possible, except when setting atime, mtime, access mode and uid/gid, where |
797 |
errors are being ignored. |
798 |
|
799 |
=cut |
800 |
|
801 |
sub aio_copy($$;$) { |
802 |
my ($src, $dst, $cb) = @_; |
803 |
|
804 |
my $pri = aioreq_pri; |
805 |
my $grp = aio_group $cb; |
806 |
|
807 |
aioreq_pri $pri; |
808 |
add $grp aio_open $src, O_RDONLY, 0, sub { |
809 |
if (my $src_fh = $_[0]) { |
810 |
my @stat = stat $src_fh; # hmm, might block over nfs? |
811 |
|
812 |
aioreq_pri $pri; |
813 |
add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { |
814 |
if (my $dst_fh = $_[0]) { |
815 |
aioreq_pri $pri; |
816 |
add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { |
817 |
if ($_[0] == $stat[7]) { |
818 |
$grp->result (0); |
819 |
close $src_fh; |
820 |
|
821 |
my $ch = sub { |
822 |
aioreq_pri $pri; |
823 |
add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub { |
824 |
aioreq_pri $pri; |
825 |
add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub { |
826 |
aioreq_pri $pri; |
827 |
add $grp aio_close $dst_fh; |
828 |
} |
829 |
}; |
830 |
}; |
831 |
|
832 |
aioreq_pri $pri; |
833 |
add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub { |
834 |
if ($_[0] < 0 && $! == ENOSYS) { |
835 |
aioreq_pri $pri; |
836 |
add $grp aio_utime $dst, $stat[8], $stat[9], $ch; |
837 |
} else { |
838 |
$ch->(); |
839 |
} |
840 |
}; |
841 |
} else { |
842 |
$grp->result (-1); |
843 |
close $src_fh; |
844 |
close $dst_fh; |
845 |
|
846 |
aioreq $pri; |
847 |
add $grp aio_unlink $dst; |
848 |
} |
849 |
}; |
850 |
} else { |
851 |
$grp->result (-1); |
852 |
} |
853 |
}, |
854 |
|
855 |
} else { |
856 |
$grp->result (-1); |
857 |
} |
858 |
}; |
859 |
|
860 |
$grp |
861 |
} |
862 |
|
863 |
=item aio_move $srcpath, $dstpath, $callback->($status) |
864 |
|
865 |
Try to move the I<file> (directories not supported as either source or |
866 |
destination) from C<$srcpath> to C<$dstpath> and call the callback with |
867 |
a status of C<0> (ok) or C<-1> (error, see C<$!>). |
868 |
|
869 |
This is a composite request that tries to rename(2) the file first; if |
870 |
rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if |
871 |
that is successful, unlinks the C<$srcpath>. |
872 |
|
873 |
=cut |
874 |
|
875 |
sub aio_move($$;$) { |
876 |
my ($src, $dst, $cb) = @_; |
877 |
|
878 |
my $pri = aioreq_pri; |
879 |
my $grp = aio_group $cb; |
880 |
|
881 |
aioreq_pri $pri; |
882 |
add $grp aio_rename $src, $dst, sub { |
883 |
if ($_[0] && $! == EXDEV) { |
884 |
aioreq_pri $pri; |
885 |
add $grp aio_copy $src, $dst, sub { |
886 |
$grp->result ($_[0]); |
887 |
|
888 |
unless ($_[0]) { |
889 |
aioreq_pri $pri; |
890 |
add $grp aio_unlink $src; |
891 |
} |
892 |
}; |
893 |
} else { |
894 |
$grp->result ($_[0]); |
895 |
} |
896 |
}; |
897 |
|
898 |
$grp |
899 |
} |
900 |
|
901 |
=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
902 |
|
903 |
Scans a directory (similar to C<aio_readdir>) but additionally tries to |
904 |
efficiently separate the entries of directory C<$path> into two sets of |
905 |
names, directories you can recurse into (directories), and ones you cannot |
906 |
recurse into (everything else, including symlinks to directories). |
907 |
|
908 |
C<aio_scandir> is a composite request that creates of many sub requests_ |
909 |
C<$maxreq> specifies the maximum number of outstanding aio requests that |
910 |
this function generates. If it is C<< <= 0 >>, then a suitable default |
911 |
will be chosen (currently 4). |
912 |
|
913 |
On error, the callback is called without arguments, otherwise it receives |
914 |
two array-refs with path-relative entry names. |
915 |
|
916 |
Example: |
917 |
|
918 |
aio_scandir $dir, 0, sub { |
919 |
my ($dirs, $nondirs) = @_; |
920 |
print "real directories: @$dirs\n"; |
921 |
print "everything else: @$nondirs\n"; |
922 |
}; |
923 |
|
924 |
Implementation notes. |
925 |
|
926 |
The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. |
927 |
|
928 |
If readdir returns file type information, then this is used directly to |
929 |
find directories. |
930 |
|
931 |
Otherwise, after reading the directory, the modification time, size etc. |
932 |
of the directory before and after the readdir is checked, and if they |
933 |
match (and isn't the current time), the link count will be used to decide |
934 |
how many entries are directories (if >= 2). Otherwise, no knowledge of the |
935 |
number of subdirectories will be assumed. |
936 |
|
937 |
Then entries will be sorted into likely directories a non-initial dot |
938 |
currently) and likely non-directories (see C<aio_readdirx>). Then every |
939 |
entry plus an appended C</.> will be C<stat>'ed, likely directories first, |
940 |
in order of their inode numbers. If that succeeds, it assumes that the |
941 |
entry is a directory or a symlink to directory (which will be checked |
942 |
separately). This is often faster than stat'ing the entry itself because |
943 |
filesystems might detect the type of the entry without reading the inode |
944 |
data (e.g. ext2fs filetype feature), even on systems that cannot return |
945 |
the filetype information on readdir. |
946 |
|
947 |
If the known number of directories (link count - 2) has been reached, the |
948 |
rest of the entries is assumed to be non-directories. |
949 |
|
950 |
This only works with certainty on POSIX (= UNIX) filesystems, which |
951 |
fortunately are the vast majority of filesystems around. |
952 |
|
953 |
It will also likely work on non-POSIX filesystems with reduced efficiency |
954 |
as those tend to return 0 or 1 as link counts, which disables the |
955 |
directory counting heuristic. |
956 |
|
957 |
=cut |
958 |
|
959 |
sub aio_scandir($$;$) { |
960 |
my ($path, $maxreq, $cb) = @_; |
961 |
|
962 |
my $pri = aioreq_pri; |
963 |
|
964 |
my $grp = aio_group $cb; |
965 |
|
966 |
$maxreq = 4 if $maxreq <= 0; |
967 |
|
968 |
# stat once |
969 |
aioreq_pri $pri; |
970 |
add $grp aio_stat $path, sub { |
971 |
return $grp->result () if $_[0]; |
972 |
my $now = time; |
973 |
my $hash1 = join ":", (stat _)[0,1,3,7,9]; |
974 |
|
975 |
# read the directory entries |
976 |
aioreq_pri $pri; |
977 |
add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { |
978 |
my $entries = shift |
979 |
or return $grp->result (); |
980 |
|
981 |
# stat the dir another time |
982 |
aioreq_pri $pri; |
983 |
add $grp aio_stat $path, sub { |
984 |
my $hash2 = join ":", (stat _)[0,1,3,7,9]; |
985 |
|
986 |
my $ndirs; |
987 |
|
988 |
# take the slow route if anything looks fishy |
989 |
if ($hash1 ne $hash2 or (stat _)[9] == $now) { |
990 |
$ndirs = -1; |
991 |
} else { |
992 |
# if nlink == 2, we are finished |
993 |
# for non-posix-fs's, we rely on nlink < 2 |
994 |
$ndirs = (stat _)[3] - 2 |
995 |
or return $grp->result ([], $entries); |
996 |
} |
997 |
|
998 |
my (@dirs, @nondirs); |
999 |
|
1000 |
my $statgrp = add $grp aio_group sub { |
1001 |
$grp->result (\@dirs, \@nondirs); |
1002 |
}; |
1003 |
|
1004 |
limit $statgrp $maxreq; |
1005 |
feed $statgrp sub { |
1006 |
return unless @$entries; |
1007 |
my $entry = shift @$entries; |
1008 |
|
1009 |
aioreq_pri $pri; |
1010 |
add $statgrp aio_stat "$path/$entry/.", sub { |
1011 |
if ($_[0] < 0) { |
1012 |
push @nondirs, $entry; |
1013 |
} else { |
1014 |
# need to check for real directory |
1015 |
aioreq_pri $pri; |
1016 |
add $statgrp aio_lstat "$path/$entry", sub { |
1017 |
if (-d _) { |
1018 |
push @dirs, $entry; |
1019 |
|
1020 |
unless (--$ndirs) { |
1021 |
push @nondirs, @$entries; |
1022 |
feed $statgrp; |
1023 |
} |
1024 |
} else { |
1025 |
push @nondirs, $entry; |
1026 |
} |
1027 |
} |
1028 |
} |
1029 |
}; |
1030 |
}; |
1031 |
}; |
1032 |
}; |
1033 |
}; |
1034 |
|
1035 |
$grp |
1036 |
} |
1037 |
|
1038 |
=item aio_rmtree $path, $callback->($status) |
1039 |
|
1040 |
Delete a directory tree starting (and including) C<$path>, return the |
1041 |
status of the final C<rmdir> only. This is a composite request that |
1042 |
uses C<aio_scandir> to recurse into and rmdir directories, and unlink |
1043 |
everything else. |
1044 |
|
1045 |
=cut |
1046 |
|
1047 |
sub aio_rmtree; |
1048 |
sub aio_rmtree($;$) { |
1049 |
my ($path, $cb) = @_; |
1050 |
|
1051 |
my $pri = aioreq_pri; |
1052 |
my $grp = aio_group $cb; |
1053 |
|
1054 |
aioreq_pri $pri; |
1055 |
add $grp aio_scandir $path, 0, sub { |
1056 |
my ($dirs, $nondirs) = @_; |
1057 |
|
1058 |
my $dirgrp = aio_group sub { |
1059 |
add $grp aio_rmdir $path, sub { |
1060 |
$grp->result ($_[0]); |
1061 |
}; |
1062 |
}; |
1063 |
|
1064 |
(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs; |
1065 |
(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs; |
1066 |
|
1067 |
add $grp $dirgrp; |
1068 |
}; |
1069 |
|
1070 |
$grp |
1071 |
} |
1072 |
|
1073 |
=item aio_sync $callback->($status) |
1074 |
|
1075 |
Asynchronously call sync and call the callback when finished. |
1076 |
|
1077 |
=item aio_fsync $fh, $callback->($status) |
1078 |
|
1079 |
Asynchronously call fsync on the given filehandle and call the callback |
1080 |
with the fsync result code. |
1081 |
|
1082 |
=item aio_fdatasync $fh, $callback->($status) |
1083 |
|
1084 |
Asynchronously call fdatasync on the given filehandle and call the |
1085 |
callback with the fdatasync result code. |
1086 |
|
1087 |
If this call isn't available because your OS lacks it or it couldn't be |
1088 |
detected, it will be emulated by calling C<fsync> instead. |
1089 |
|
1090 |
=item aio_syncfs $fh, $callback->($status) |
1091 |
|
1092 |
Asynchronously call the syncfs syscall to sync the filesystem associated |
1093 |
to the given filehandle and call the callback with the syncfs result |
1094 |
code. If syncfs is not available, calls sync(), but returns C<-1> and sets |
1095 |
errno to C<ENOSYS> nevertheless. |
1096 |
|
1097 |
=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
1098 |
|
1099 |
Sync the data portion of the file specified by C<$offset> and C<$length> |
1100 |
to disk (but NOT the metadata), by calling the Linux-specific |
1101 |
sync_file_range call. If sync_file_range is not available or it returns |
1102 |
ENOSYS, then fdatasync or fsync is being substituted. |
1103 |
|
1104 |
C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, |
1105 |
C<IO::AIO::SYNC_FILE_RANGE_WRITE> and |
1106 |
C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range |
1107 |
manpage for details. |
1108 |
|
1109 |
=item aio_pathsync $path, $callback->($status) |
1110 |
|
1111 |
This request tries to open, fsync and close the given path. This is a |
1112 |
composite request intended to sync directories after directory operations |
1113 |
(E.g. rename). This might not work on all operating systems or have any |
1114 |
specific effect, but usually it makes sure that directory changes get |
1115 |
written to disc. It works for anything that can be opened for read-only, |
1116 |
not just directories. |
1117 |
|
1118 |
Future versions of this function might fall back to other methods when |
1119 |
C<fsync> on the directory fails (such as calling C<sync>). |
1120 |
|
1121 |
Passes C<0> when everything went ok, and C<-1> on error. |
1122 |
|
1123 |
=cut |
1124 |
|
1125 |
sub aio_pathsync($;$) { |
1126 |
my ($path, $cb) = @_; |
1127 |
|
1128 |
my $pri = aioreq_pri; |
1129 |
my $grp = aio_group $cb; |
1130 |
|
1131 |
aioreq_pri $pri; |
1132 |
add $grp aio_open $path, O_RDONLY, 0, sub { |
1133 |
my ($fh) = @_; |
1134 |
if ($fh) { |
1135 |
aioreq_pri $pri; |
1136 |
add $grp aio_fsync $fh, sub { |
1137 |
$grp->result ($_[0]); |
1138 |
|
1139 |
aioreq_pri $pri; |
1140 |
add $grp aio_close $fh; |
1141 |
}; |
1142 |
} else { |
1143 |
$grp->result (-1); |
1144 |
} |
1145 |
}; |
1146 |
|
1147 |
$grp |
1148 |
} |
1149 |
|
1150 |
=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
1151 |
|
1152 |
This is a rather advanced IO::AIO call, which only works on mmap(2)ed |
1153 |
scalars (see the C<IO::AIO::mmap> function, although it also works on data |
1154 |
scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the |
1155 |
scalar must only be modified in-place while an aio operation is pending on |
1156 |
it). |
1157 |
|
1158 |
It calls the C<msync> function of your OS, if available, with the memory |
1159 |
area starting at C<$offset> in the string and ending C<$length> bytes |
1160 |
later. If C<$length> is negative, counts from the end, and if C<$length> |
1161 |
is C<undef>, then it goes till the end of the string. The flags can be |
1162 |
a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and |
1163 |
C<IO::AIO::MS_SYNC>. |
1164 |
|
1165 |
=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
1166 |
|
1167 |
This is a rather advanced IO::AIO call, which works best on mmap(2)ed |
1168 |
scalars. |
1169 |
|
1170 |
It touches (reads or writes) all memory pages in the specified |
1171 |
range inside the scalar. All caveats and parameters are the same |
1172 |
as for C<aio_msync>, above, except for flags, which must be either |
1173 |
C<0> (which reads all pages and ensures they are instantiated) or |
1174 |
C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and |
1175 |
writing an octet from it, which dirties the page). |
1176 |
|
1177 |
=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
1178 |
|
1179 |
This is a rather advanced IO::AIO call, which works best on mmap(2)ed |
1180 |
scalars. |
1181 |
|
1182 |
It reads in all the pages of the underlying storage into memory (if any) |
1183 |
and locks them, so they are not getting swapped/paged out or removed. |
1184 |
|
1185 |
If C<$length> is undefined, then the scalar will be locked till the end. |
1186 |
|
1187 |
On systems that do not implement C<mlock>, this function returns C<-1> |
1188 |
and sets errno to C<ENOSYS>. |
1189 |
|
1190 |
Note that the corresponding C<munlock> is synchronous and is |
1191 |
documented under L<MISCELLANEOUS FUNCTIONS>. |
1192 |
|
1193 |
Example: open a file, mmap and mlock it - both will be undone when |
1194 |
C<$data> gets destroyed. |
1195 |
|
1196 |
open my $fh, "<", $path or die "$path: $!"; |
1197 |
my $data; |
1198 |
IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; |
1199 |
aio_mlock $data; # mlock in background |
1200 |
|
1201 |
=item aio_mlockall $flags, $callback->($status) |
1202 |
|
1203 |
Calls the C<mlockall> function with the given C<$flags> (a combination of |
1204 |
C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>). |
1205 |
|
1206 |
On systems that do not implement C<mlockall>, this function returns C<-1> |
1207 |
and sets errno to C<ENOSYS>. |
1208 |
|
1209 |
Note that the corresponding C<munlockall> is synchronous and is |
1210 |
documented under L<MISCELLANEOUS FUNCTIONS>. |
1211 |
|
1212 |
Example: asynchronously lock all current and future pages into memory. |
1213 |
|
1214 |
aio_mlockall IO::AIO::MCL_FUTURE; |
1215 |
|
1216 |
=item aio_group $callback->(...) |
1217 |
|
1218 |
This is a very special aio request: Instead of doing something, it is a |
1219 |
container for other aio requests, which is useful if you want to bundle |
1220 |
many requests into a single, composite, request with a definite callback |
1221 |
and the ability to cancel the whole request with its subrequests. |
1222 |
|
1223 |
Returns an object of class L<IO::AIO::GRP>. See its documentation below |
1224 |
for more info. |
1225 |
|
1226 |
Example: |
1227 |
|
1228 |
my $grp = aio_group sub { |
1229 |
print "all stats done\n"; |
1230 |
}; |
1231 |
|
1232 |
add $grp |
1233 |
(aio_stat ...), |
1234 |
(aio_stat ...), |
1235 |
...; |
1236 |
|
1237 |
=item aio_nop $callback->() |
1238 |
|
1239 |
This is a special request - it does nothing in itself and is only used for |
1240 |
side effects, such as when you want to add a dummy request to a group so |
1241 |
that finishing the requests in the group depends on executing the given |
1242 |
code. |
1243 |
|
1244 |
While this request does nothing, it still goes through the execution |
1245 |
phase and still requires a worker thread. Thus, the callback will not |
1246 |
be executed immediately but only after other requests in the queue have |
1247 |
entered their execution phase. This can be used to measure request |
1248 |
latency. |
1249 |
|
1250 |
=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
1251 |
|
1252 |
Mainly used for debugging and benchmarking, this aio request puts one of |
1253 |
the request workers to sleep for the given time. |
1254 |
|
1255 |
While it is theoretically handy to have simple I/O scheduling requests |
1256 |
like sleep and file handle readable/writable, the overhead this creates is |
1257 |
immense (it blocks a thread for a long time) so do not use this function |
1258 |
except to put your application under artificial I/O pressure. |
1259 |
|
1260 |
=back |
1261 |
|
1262 |
=head2 IO::AIO::REQ CLASS |
1263 |
|
1264 |
All non-aggregate C<aio_*> functions return an object of this class when |
1265 |
called in non-void context. |
1266 |
|
1267 |
=over 4 |
1268 |
|
1269 |
=item cancel $req |
1270 |
|
1271 |
Cancels the request, if possible. Has the effect of skipping execution |
1272 |
when entering the B<execute> state and skipping calling the callback when |
1273 |
entering the the B<result> state, but will leave the request otherwise |
1274 |
untouched (with the exception of readdir). That means that requests that |
1275 |
currently execute will not be stopped and resources held by the request |
1276 |
will not be freed prematurely. |
1277 |
|
1278 |
=item cb $req $callback->(...) |
1279 |
|
1280 |
Replace (or simply set) the callback registered to the request. |
1281 |
|
1282 |
=back |
1283 |
|
1284 |
=head2 IO::AIO::GRP CLASS |
1285 |
|
1286 |
This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to |
1287 |
objects of this class, too. |
1288 |
|
1289 |
A IO::AIO::GRP object is a special request that can contain multiple other |
1290 |
aio requests. |
1291 |
|
1292 |
You create one by calling the C<aio_group> constructing function with a |
1293 |
callback that will be called when all contained requests have entered the |
1294 |
C<done> state: |
1295 |
|
1296 |
my $grp = aio_group sub { |
1297 |
print "all requests are done\n"; |
1298 |
}; |
1299 |
|
1300 |
You add requests by calling the C<add> method with one or more |
1301 |
C<IO::AIO::REQ> objects: |
1302 |
|
1303 |
$grp->add (aio_unlink "..."); |
1304 |
|
1305 |
add $grp aio_stat "...", sub { |
1306 |
$_[0] or return $grp->result ("error"); |
1307 |
|
1308 |
# add another request dynamically, if first succeeded |
1309 |
add $grp aio_open "...", sub { |
1310 |
$grp->result ("ok"); |
1311 |
}; |
1312 |
}; |
1313 |
|
1314 |
This makes it very easy to create composite requests (see the source of |
1315 |
C<aio_move> for an application) that work and feel like simple requests. |
1316 |
|
1317 |
=over 4 |
1318 |
|
1319 |
=item * The IO::AIO::GRP objects will be cleaned up during calls to |
1320 |
C<IO::AIO::poll_cb>, just like any other request. |
1321 |
|
1322 |
=item * They can be canceled like any other request. Canceling will cancel not |
1323 |
only the request itself, but also all requests it contains. |
1324 |
|
1325 |
=item * They can also can also be added to other IO::AIO::GRP objects. |
1326 |
|
1327 |
=item * You must not add requests to a group from within the group callback (or |
1328 |
any later time). |
1329 |
|
1330 |
=back |
1331 |
|
1332 |
Their lifetime, simplified, looks like this: when they are empty, they |
1333 |
will finish very quickly. If they contain only requests that are in the |
1334 |
C<done> state, they will also finish. Otherwise they will continue to |
1335 |
exist. |
1336 |
|
1337 |
That means after creating a group you have some time to add requests |
1338 |
(precisely before the callback has been invoked, which is only done within |
1339 |
the C<poll_cb>). And in the callbacks of those requests, you can add |
1340 |
further requests to the group. And only when all those requests have |
1341 |
finished will the the group itself finish. |
1342 |
|
1343 |
=over 4 |
1344 |
|
1345 |
=item add $grp ... |
1346 |
|
1347 |
=item $grp->add (...) |
1348 |
|
1349 |
Add one or more requests to the group. Any type of L<IO::AIO::REQ> can |
1350 |
be added, including other groups, as long as you do not create circular |
1351 |
dependencies. |
1352 |
|
1353 |
Returns all its arguments. |
1354 |
|
1355 |
=item $grp->cancel_subs |
1356 |
|
1357 |
Cancel all subrequests and clears any feeder, but not the group request |
1358 |
itself. Useful when you queued a lot of events but got a result early. |
1359 |
|
1360 |
The group request will finish normally (you cannot add requests to the |
1361 |
group). |
1362 |
|
1363 |
=item $grp->result (...) |
1364 |
|
1365 |
Set the result value(s) that will be passed to the group callback when all |
1366 |
subrequests have finished and set the groups errno to the current value |
1367 |
of errno (just like calling C<errno> without an error number). By default, |
1368 |
no argument will be passed and errno is zero. |
1369 |
|
1370 |
=item $grp->errno ([$errno]) |
1371 |
|
1372 |
Sets the group errno value to C<$errno>, or the current value of errno |
1373 |
when the argument is missing. |
1374 |
|
1375 |
Every aio request has an associated errno value that is restored when |
1376 |
the callback is invoked. This method lets you change this value from its |
1377 |
default (0). |
1378 |
|
1379 |
Calling C<result> will also set errno, so make sure you either set C<$!> |
1380 |
before the call to C<result>, or call c<errno> after it. |
1381 |
|
1382 |
=item feed $grp $callback->($grp) |
1383 |
|
1384 |
Sets a feeder/generator on this group: every group can have an attached |
1385 |
generator that generates requests if idle. The idea behind this is that, |
1386 |
although you could just queue as many requests as you want in a group, |
1387 |
this might starve other requests for a potentially long time. For example, |
1388 |
C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, |
1389 |
delaying any later requests for a long time. |
1390 |
|
1391 |
To avoid this, and allow incremental generation of requests, you can |
1392 |
instead a group and set a feeder on it that generates those requests. The |
1393 |
feed callback will be called whenever there are few enough (see C<limit>, |
1394 |
below) requests active in the group itself and is expected to queue more |
1395 |
requests. |
1396 |
|
1397 |
The feed callback can queue as many requests as it likes (i.e. C<add> does |
1398 |
not impose any limits). |
1399 |
|
1400 |
If the feed does not queue more requests when called, it will be |
1401 |
automatically removed from the group. |
1402 |
|
1403 |
If the feed limit is C<0> when this method is called, it will be set to |
1404 |
C<2> automatically. |
1405 |
|
1406 |
Example: |
1407 |
|
1408 |
# stat all files in @files, but only ever use four aio requests concurrently: |
1409 |
|
1410 |
my $grp = aio_group sub { print "finished\n" }; |
1411 |
limit $grp 4; |
1412 |
feed $grp sub { |
1413 |
my $file = pop @files |
1414 |
or return; |
1415 |
|
1416 |
add $grp aio_stat $file, sub { ... }; |
1417 |
}; |
1418 |
|
1419 |
=item limit $grp $num |
1420 |
|
1421 |
Sets the feeder limit for the group: The feeder will be called whenever |
1422 |
the group contains less than this many requests. |
1423 |
|
1424 |
Setting the limit to C<0> will pause the feeding process. |
1425 |
|
1426 |
The default value for the limit is C<0>, but note that setting a feeder |
1427 |
automatically bumps it up to C<2>. |
1428 |
|
1429 |
=back |
1430 |
|
1431 |
=head2 SUPPORT FUNCTIONS |
1432 |
|
1433 |
=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
1434 |
|
1435 |
=over 4 |
1436 |
|
1437 |
=item $fileno = IO::AIO::poll_fileno |
1438 |
|
1439 |
Return the I<request result pipe file descriptor>. This filehandle must be |
1440 |
polled for reading by some mechanism outside this module (e.g. EV, Glib, |
1441 |
select and so on, see below or the SYNOPSIS). If the pipe becomes readable |
1442 |
you have to call C<poll_cb> to check the results. |
1443 |
|
1444 |
See C<poll_cb> for an example. |
1445 |
|
1446 |
=item IO::AIO::poll_cb |
1447 |
|
1448 |
Process some outstanding events on the result pipe. You have to call |
1449 |
this regularly. Returns C<0> if all events could be processed (or there |
1450 |
were no events to process), or C<-1> if it returned earlier for whatever |
1451 |
reason. Returns immediately when no events are outstanding. The amount of |
1452 |
events processed depends on the settings of C<IO::AIO::max_poll_req> and |
1453 |
C<IO::AIO::max_poll_time>. |
1454 |
|
1455 |
If not all requests were processed for whatever reason, the filehandle |
1456 |
will still be ready when C<poll_cb> returns, so normally you don't have to |
1457 |
do anything special to have it called later. |
1458 |
|
1459 |
Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes |
1460 |
ready, it can be beneficial to call this function from loops which submit |
1461 |
a lot of requests, to make sure the results get processed when they become |
1462 |
available and not just when the loop is finished and the event loop takes |
1463 |
over again. This function returns very fast when there are no outstanding |
1464 |
requests. |
1465 |
|
1466 |
Example: Install an Event watcher that automatically calls |
1467 |
IO::AIO::poll_cb with high priority (more examples can be found in the |
1468 |
SYNOPSIS section, at the top of this document): |
1469 |
|
1470 |
Event->io (fd => IO::AIO::poll_fileno, |
1471 |
poll => 'r', async => 1, |
1472 |
cb => \&IO::AIO::poll_cb); |
1473 |
|
1474 |
=item IO::AIO::poll_wait |
1475 |
|
1476 |
If there are any outstanding requests and none of them in the result |
1477 |
phase, wait till the result filehandle becomes ready for reading (simply |
1478 |
does a C<select> on the filehandle. This is useful if you want to |
1479 |
synchronously wait for some requests to finish). |
1480 |
|
1481 |
See C<nreqs> for an example. |
1482 |
|
1483 |
=item IO::AIO::poll |
1484 |
|
1485 |
Waits until some requests have been handled. |
1486 |
|
1487 |
Returns the number of requests processed, but is otherwise strictly |
1488 |
equivalent to: |
1489 |
|
1490 |
IO::AIO::poll_wait, IO::AIO::poll_cb |
1491 |
|
1492 |
=item IO::AIO::flush |
1493 |
|
1494 |
Wait till all outstanding AIO requests have been handled. |
1495 |
|
1496 |
Strictly equivalent to: |
1497 |
|
1498 |
IO::AIO::poll_wait, IO::AIO::poll_cb |
1499 |
while IO::AIO::nreqs; |
1500 |
|
1501 |
=item IO::AIO::max_poll_reqs $nreqs |
1502 |
|
1503 |
=item IO::AIO::max_poll_time $seconds |
1504 |
|
1505 |
These set the maximum number of requests (default C<0>, meaning infinity) |
1506 |
that are being processed by C<IO::AIO::poll_cb> in one call, respectively |
1507 |
the maximum amount of time (default C<0>, meaning infinity) spent in |
1508 |
C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount |
1509 |
of time C<poll_cb> is allowed to use). |
1510 |
|
1511 |
Setting C<max_poll_time> to a non-zero value creates an overhead of one |
1512 |
syscall per request processed, which is not normally a problem unless your |
1513 |
callbacks are really really fast or your OS is really really slow (I am |
1514 |
not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead. |
1515 |
|
1516 |
Setting these is useful if you want to ensure some level of |
1517 |
interactiveness when perl is not fast enough to process all requests in |
1518 |
time. |
1519 |
|
1520 |
For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
1521 |
|
1522 |
Example: Install an Event watcher that automatically calls |
1523 |
IO::AIO::poll_cb with low priority, to ensure that other parts of the |
1524 |
program get the CPU sometimes even under high AIO load. |
1525 |
|
1526 |
# try not to spend much more than 0.1s in poll_cb |
1527 |
IO::AIO::max_poll_time 0.1; |
1528 |
|
1529 |
# use a low priority so other tasks have priority |
1530 |
Event->io (fd => IO::AIO::poll_fileno, |
1531 |
poll => 'r', nice => 1, |
1532 |
cb => &IO::AIO::poll_cb); |
1533 |
|
1534 |
=back |
1535 |
|
1536 |
=head3 CONTROLLING THE NUMBER OF THREADS |
1537 |
|
1538 |
=over |
1539 |
|
1540 |
=item IO::AIO::min_parallel $nthreads |
1541 |
|
1542 |
Set the minimum number of AIO threads to C<$nthreads>. The current |
1543 |
default is C<8>, which means eight asynchronous operations can execute |
1544 |
concurrently at any one time (the number of outstanding requests, |
1545 |
however, is unlimited). |
1546 |
|
1547 |
IO::AIO starts threads only on demand, when an AIO request is queued and |
1548 |
no free thread exists. Please note that queueing up a hundred requests can |
1549 |
create demand for a hundred threads, even if it turns out that everything |
1550 |
is in the cache and could have been processed faster by a single thread. |
1551 |
|
1552 |
It is recommended to keep the number of threads relatively low, as some |
1553 |
Linux kernel versions will scale negatively with the number of threads |
1554 |
(higher parallelity => MUCH higher latency). With current Linux 2.6 |
1555 |
versions, 4-32 threads should be fine. |
1556 |
|
1557 |
Under most circumstances you don't need to call this function, as the |
1558 |
module selects a default that is suitable for low to moderate load. |
1559 |
|
1560 |
=item IO::AIO::max_parallel $nthreads |
1561 |
|
1562 |
Sets the maximum number of AIO threads to C<$nthreads>. If more than the |
1563 |
specified number of threads are currently running, this function kills |
1564 |
them. This function blocks until the limit is reached. |
1565 |
|
1566 |
While C<$nthreads> are zero, aio requests get queued but not executed |
1567 |
until the number of threads has been increased again. |
1568 |
|
1569 |
This module automatically runs C<max_parallel 0> at program end, to ensure |
1570 |
that all threads are killed and that there are no outstanding requests. |
1571 |
|
1572 |
Under normal circumstances you don't need to call this function. |
1573 |
|
1574 |
=item IO::AIO::max_idle $nthreads |
1575 |
|
1576 |
Limit the number of threads (default: 4) that are allowed to idle |
1577 |
(i.e., threads that did not get a request to process within the idle |
1578 |
timeout (default: 10 seconds). That means if a thread becomes idle while |
1579 |
C<$nthreads> other threads are also idle, it will free its resources and |
1580 |
exit. |
1581 |
|
1582 |
This is useful when you allow a large number of threads (e.g. 100 or 1000) |
1583 |
to allow for extremely high load situations, but want to free resources |
1584 |
under normal circumstances (1000 threads can easily consume 30MB of RAM). |
1585 |
|
1586 |
The default is probably ok in most situations, especially if thread |
1587 |
creation is fast. If thread creation is very slow on your system you might |
1588 |
want to use larger values. |
1589 |
|
1590 |
=item IO::AIO::idle_timeout $seconds |
1591 |
|
1592 |
Sets the minimum idle timeout (default 10) after which worker threads are |
1593 |
allowed to exit. SEe C<IO::AIO::max_idle>. |
1594 |
|
1595 |
=item IO::AIO::max_outstanding $maxreqs |
1596 |
|
1597 |
Sets the maximum number of outstanding requests to C<$nreqs>. If |
1598 |
you do queue up more than this number of requests, the next call to |
1599 |
C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as |
1600 |
C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no |
1601 |
longer exceeded. |
1602 |
|
1603 |
In other words, this setting does not enforce a queue limit, but can be |
1604 |
used to make poll functions block if the limit is exceeded. |
1605 |
|
1606 |
This is a very bad function to use in interactive programs because it |
1607 |
blocks, and a bad way to reduce concurrency because it is inexact: Better |
1608 |
use an C<aio_group> together with a feed callback. |
1609 |
|
1610 |
It's main use is in scripts without an event loop - when you want to stat |
1611 |
a lot of files, you can write somehting like this: |
1612 |
|
1613 |
IO::AIO::max_outstanding 32; |
1614 |
|
1615 |
for my $path (...) { |
1616 |
aio_stat $path , ...; |
1617 |
IO::AIO::poll_cb; |
1618 |
} |
1619 |
|
1620 |
IO::AIO::flush; |
1621 |
|
1622 |
The call to C<poll_cb> inside the loop will normally return instantly, but |
1623 |
as soon as more thna C<32> reqeusts are in-flight, it will block until |
1624 |
some requests have been handled. This keeps the loop from pushing a large |
1625 |
number of C<aio_stat> requests onto the queue. |
1626 |
|
1627 |
The default value for C<max_outstanding> is very large, so there is no |
1628 |
practical limit on the number of outstanding requests. |
1629 |
|
1630 |
=back |
1631 |
|
1632 |
=head3 STATISTICAL INFORMATION |
1633 |
|
1634 |
=over |
1635 |
|
1636 |
=item IO::AIO::nreqs |
1637 |
|
1638 |
Returns the number of requests currently in the ready, execute or pending |
1639 |
states (i.e. for which their callback has not been invoked yet). |
1640 |
|
1641 |
Example: wait till there are no outstanding requests anymore: |
1642 |
|
1643 |
IO::AIO::poll_wait, IO::AIO::poll_cb |
1644 |
while IO::AIO::nreqs; |
1645 |
|
1646 |
=item IO::AIO::nready |
1647 |
|
1648 |
Returns the number of requests currently in the ready state (not yet |
1649 |
executed). |
1650 |
|
1651 |
=item IO::AIO::npending |
1652 |
|
1653 |
Returns the number of requests currently in the pending state (executed, |
1654 |
but not yet processed by poll_cb). |
1655 |
|
1656 |
=back |
1657 |
|
1658 |
=head3 MISCELLANEOUS FUNCTIONS |
1659 |
|
1660 |
IO::AIO implements some functions that might be useful, but are not |
1661 |
asynchronous. |
1662 |
|
1663 |
=over 4 |
1664 |
|
1665 |
=item IO::AIO::sendfile $ofh, $ifh, $offset, $count |
1666 |
|
1667 |
Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>, |
1668 |
but is blocking (this makes most sense if you know the input data is |
1669 |
likely cached already and the output filehandle is set to non-blocking |
1670 |
operations). |
1671 |
|
1672 |
Returns the number of bytes copied, or C<-1> on error. |
1673 |
|
1674 |
=item IO::AIO::fadvise $fh, $offset, $len, $advice |
1675 |
|
1676 |
Simply calls the C<posix_fadvise> function (see its |
1677 |
manpage for details). The following advice constants are |
1678 |
available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>, |
1679 |
C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>, |
1680 |
C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>. |
1681 |
|
1682 |
On systems that do not implement C<posix_fadvise>, this function returns |
1683 |
ENOSYS, otherwise the return value of C<posix_fadvise>. |
1684 |
|
1685 |
=item IO::AIO::madvise $scalar, $offset, $len, $advice |
1686 |
|
1687 |
Simply calls the C<posix_madvise> function (see its |
1688 |
manpage for details). The following advice constants are |
1689 |
available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, |
1690 |
C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>. |
1691 |
|
1692 |
On systems that do not implement C<posix_madvise>, this function returns |
1693 |
ENOSYS, otherwise the return value of C<posix_madvise>. |
1694 |
|
1695 |
=item IO::AIO::mprotect $scalar, $offset, $len, $protect |
1696 |
|
1697 |
Simply calls the C<mprotect> function on the preferably AIO::mmap'ed |
1698 |
$scalar (see its manpage for details). The following protect |
1699 |
constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, |
1700 |
C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. |
1701 |
|
1702 |
On systems that do not implement C<mprotect>, this function returns |
1703 |
ENOSYS, otherwise the return value of C<mprotect>. |
1704 |
|
1705 |
=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] |
1706 |
|
1707 |
Memory-maps a file (or anonymous memory range) and attaches it to the |
1708 |
given C<$scalar>, which will act like a string scalar. |
1709 |
|
1710 |
The only operations allowed on the scalar are C<substr>/C<vec> that don't |
1711 |
change the string length, and most read-only operations such as copying it |
1712 |
or searching it with regexes and so on. |
1713 |
|
1714 |
Anything else is unsafe and will, at best, result in memory leaks. |
1715 |
|
1716 |
The memory map associated with the C<$scalar> is automatically removed |
1717 |
when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or |
1718 |
C<IO::AIO::munmap> functions are called. |
1719 |
|
1720 |
This calls the C<mmap>(2) function internally. See your system's manual |
1721 |
page for details on the C<$length>, C<$prot> and C<$flags> parameters. |
1722 |
|
1723 |
The C<$length> must be larger than zero and smaller than the actual |
1724 |
filesize. |
1725 |
|
1726 |
C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, |
1727 |
C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, |
1728 |
|
1729 |
C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or |
1730 |
C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when |
1731 |
not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS> |
1732 |
(which is set to C<MAP_ANON> if your system only provides this |
1733 |
constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>, |
1734 |
C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or |
1735 |
C<IO::AIO::MAP_NONBLOCK> |
1736 |
|
1737 |
If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. |
1738 |
|
1739 |
C<$offset> is the offset from the start of the file - it generally must be |
1740 |
a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. |
1741 |
|
1742 |
Example: |
1743 |
|
1744 |
use Digest::MD5; |
1745 |
use IO::AIO; |
1746 |
|
1747 |
open my $fh, "<verybigfile" |
1748 |
or die "$!"; |
1749 |
|
1750 |
IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh |
1751 |
or die "verybigfile: $!"; |
1752 |
|
1753 |
my $fast_md5 = md5 $data; |
1754 |
|
1755 |
=item IO::AIO::munmap $scalar |
1756 |
|
1757 |
Removes a previous mmap and undefines the C<$scalar>. |
1758 |
|
1759 |
=item IO::AIO::munlock $scalar, $offset = 0, $length = undef |
1760 |
|
1761 |
Calls the C<munlock> function, undoing the effects of a previous |
1762 |
C<aio_mlock> call (see its description for details). |
1763 |
|
1764 |
=item IO::AIO::munlockall |
1765 |
|
1766 |
Calls the C<munlockall> function. |
1767 |
|
1768 |
On systems that do not implement C<munlockall>, this function returns |
1769 |
ENOSYS, otherwise the return value of C<munlockall>. |
1770 |
|
1771 |
=back |
1772 |
|
1773 |
=cut |
1774 |
|
1775 |
min_parallel 8; |
1776 |
|
1777 |
END { flush } |
1778 |
|
1779 |
1; |
1780 |
|
1781 |
=head1 EVENT LOOP INTEGRATION |
1782 |
|
1783 |
It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO |
1784 |
automatically into many event loops: |
1785 |
|
1786 |
# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
1787 |
use AnyEvent::AIO; |
1788 |
|
1789 |
You can also integrate IO::AIO manually into many event loops, here are |
1790 |
some examples of how to do this: |
1791 |
|
1792 |
# EV integration |
1793 |
my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
1794 |
|
1795 |
# Event integration |
1796 |
Event->io (fd => IO::AIO::poll_fileno, |
1797 |
poll => 'r', |
1798 |
cb => \&IO::AIO::poll_cb); |
1799 |
|
1800 |
# Glib/Gtk2 integration |
1801 |
add_watch Glib::IO IO::AIO::poll_fileno, |
1802 |
in => sub { IO::AIO::poll_cb; 1 }; |
1803 |
|
1804 |
# Tk integration |
1805 |
Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
1806 |
readable => \&IO::AIO::poll_cb); |
1807 |
|
1808 |
# Danga::Socket integration |
1809 |
Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
1810 |
\&IO::AIO::poll_cb); |
1811 |
|
1812 |
=head2 FORK BEHAVIOUR |
1813 |
|
1814 |
Usage of pthreads in a program changes the semantics of fork |
1815 |
considerably. Specifically, only async-safe functions can be called after |
1816 |
fork. Perl doesn't know about this, so in general, you cannot call fork |
1817 |
with defined behaviour in perl if pthreads are involved. IO::AIO uses |
1818 |
pthreads, so this applies, but many other extensions and (for inexplicable |
1819 |
reasons) perl itself often is linked against pthreads, so this limitation |
1820 |
applies to quite a lot of perls. |
1821 |
|
1822 |
This module no longer tries to fight your OS, or POSIX. That means IO::AIO |
1823 |
only works in the process that loaded it. Forking is fully supported, but |
1824 |
using IO::AIO in the child is not. |
1825 |
|
1826 |
You might get around by not I<using> IO::AIO before (or after) |
1827 |
forking. You could also try to call the L<IO::AIO::reinit> function in the |
1828 |
child: |
1829 |
|
1830 |
=over 4 |
1831 |
|
1832 |
=item IO::AIO::reinit |
1833 |
|
1834 |
Abandons all current requests and I/O threads and simply reinitialises all |
1835 |
data structures. This is not an operation supported by any standards, but |
1836 |
happens to work on GNU/Linux and some newer BSD systems. |
1837 |
|
1838 |
The only reasonable use for this function is to call it after forking, if |
1839 |
C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in |
1840 |
the process will result in undefined behaviour. Calling it at any time |
1841 |
will also result in any undefined (by POSIX) behaviour. |
1842 |
|
1843 |
=back |
1844 |
|
1845 |
=head2 MEMORY USAGE |
1846 |
|
1847 |
Per-request usage: |
1848 |
|
1849 |
Each aio request uses - depending on your architecture - around 100-200 |
1850 |
bytes of memory. In addition, stat requests need a stat buffer (possibly |
1851 |
a few hundred bytes), readdir requires a result buffer and so on. Perl |
1852 |
scalars and other data passed into aio requests will also be locked and |
1853 |
will consume memory till the request has entered the done state. |
1854 |
|
1855 |
This is not awfully much, so queuing lots of requests is not usually a |
1856 |
problem. |
1857 |
|
1858 |
Per-thread usage: |
1859 |
|
1860 |
In the execution phase, some aio requests require more memory for |
1861 |
temporary buffers, and each thread requires a stack and other data |
1862 |
structures (usually around 16k-128k, depending on the OS). |
1863 |
|
1864 |
=head1 KNOWN BUGS |
1865 |
|
1866 |
Known bugs will be fixed in the next release. |
1867 |
|
1868 |
=head1 SEE ALSO |
1869 |
|
1870 |
L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a |
1871 |
more natural syntax. |
1872 |
|
1873 |
=head1 AUTHOR |
1874 |
|
1875 |
Marc Lehmann <schmorp@schmorp.de> |
1876 |
http://home.schmorp.de/ |
1877 |
|
1878 |
=cut |
1879 |
|