1 |
=head1 NAME |
2 |
|
3 |
IO::AIO - Asynchronous/Advanced 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 |
In addition to asynchronous I/O, this module also exports some rather |
64 |
arcane interfaces, such as C<madvise> or linux's C<splice> system call, |
65 |
which is why the C<A> in C<AIO> can also mean I<advanced>. |
66 |
|
67 |
Although the module will work in the presence of other (Perl-) threads, |
68 |
it is currently not reentrant in any way, so use appropriate locking |
69 |
yourself, always call C<poll_cb> from within the same thread, or never |
70 |
call C<poll_cb> (or other C<aio_> functions) recursively. |
71 |
|
72 |
=head2 EXAMPLE |
73 |
|
74 |
This is a simple example that uses the EV module and loads |
75 |
F</etc/passwd> asynchronously: |
76 |
|
77 |
use EV; |
78 |
use IO::AIO; |
79 |
|
80 |
# register the IO::AIO callback with EV |
81 |
my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
82 |
|
83 |
# queue the request to open /etc/passwd |
84 |
aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
85 |
my $fh = shift |
86 |
or die "error while opening: $!"; |
87 |
|
88 |
# stat'ing filehandles is generally non-blocking |
89 |
my $size = -s $fh; |
90 |
|
91 |
# queue a request to read the file |
92 |
my $contents; |
93 |
aio_read $fh, 0, $size, $contents, 0, sub { |
94 |
$_[0] == $size |
95 |
or die "short read: $!"; |
96 |
|
97 |
close $fh; |
98 |
|
99 |
# file contents now in $contents |
100 |
print $contents; |
101 |
|
102 |
# exit event loop and program |
103 |
EV::break; |
104 |
}; |
105 |
}; |
106 |
|
107 |
# possibly queue up other requests, or open GUI windows, |
108 |
# check for sockets etc. etc. |
109 |
|
110 |
# process events as long as there are some: |
111 |
EV::run; |
112 |
|
113 |
=head1 REQUEST ANATOMY AND LIFETIME |
114 |
|
115 |
Every C<aio_*> function creates a request. which is a C data structure not |
116 |
directly visible to Perl. |
117 |
|
118 |
If called in non-void context, every request function returns a Perl |
119 |
object representing the request. In void context, nothing is returned, |
120 |
which saves a bit of memory. |
121 |
|
122 |
The perl object is a fairly standard ref-to-hash object. The hash contents |
123 |
are not used by IO::AIO so you are free to store anything you like in it. |
124 |
|
125 |
During their existance, aio requests travel through the following states, |
126 |
in order: |
127 |
|
128 |
=over 4 |
129 |
|
130 |
=item ready |
131 |
|
132 |
Immediately after a request is created it is put into the ready state, |
133 |
waiting for a thread to execute it. |
134 |
|
135 |
=item execute |
136 |
|
137 |
A thread has accepted the request for processing and is currently |
138 |
executing it (e.g. blocking in read). |
139 |
|
140 |
=item pending |
141 |
|
142 |
The request has been executed and is waiting for result processing. |
143 |
|
144 |
While request submission and execution is fully asynchronous, result |
145 |
processing is not and relies on the perl interpreter calling C<poll_cb> |
146 |
(or another function with the same effect). |
147 |
|
148 |
=item result |
149 |
|
150 |
The request results are processed synchronously by C<poll_cb>. |
151 |
|
152 |
The C<poll_cb> function will process all outstanding aio requests by |
153 |
calling their callbacks, freeing memory associated with them and managing |
154 |
any groups they are contained in. |
155 |
|
156 |
=item done |
157 |
|
158 |
Request has reached the end of its lifetime and holds no resources anymore |
159 |
(except possibly for the Perl object, but its connection to the actual |
160 |
aio request is severed and calling its methods will either do nothing or |
161 |
result in a runtime error). |
162 |
|
163 |
=back |
164 |
|
165 |
=cut |
166 |
|
167 |
package IO::AIO; |
168 |
|
169 |
use Carp (); |
170 |
|
171 |
use common::sense; |
172 |
|
173 |
use base 'Exporter'; |
174 |
|
175 |
BEGIN { |
176 |
our $VERSION = 4.4; |
177 |
|
178 |
our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close |
179 |
aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx |
180 |
aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl |
181 |
aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range |
182 |
aio_pathsync aio_readahead aio_fiemap aio_allocate |
183 |
aio_rename aio_rename2 aio_link aio_move aio_copy aio_group |
184 |
aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown |
185 |
aio_chmod aio_utime aio_truncate |
186 |
aio_msync aio_mtouch aio_mlock aio_mlockall |
187 |
aio_statvfs |
188 |
aio_slurp |
189 |
aio_wd); |
190 |
|
191 |
our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
192 |
our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
193 |
min_parallel max_parallel max_idle idle_timeout |
194 |
nreqs nready npending nthreads |
195 |
max_poll_time max_poll_reqs |
196 |
sendfile fadvise madvise |
197 |
mmap munmap munlock munlockall); |
198 |
|
199 |
push @AIO_REQ, qw(aio_busy); # not exported |
200 |
|
201 |
@IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
202 |
|
203 |
require XSLoader; |
204 |
XSLoader::load ("IO::AIO", $VERSION); |
205 |
} |
206 |
|
207 |
=head1 FUNCTIONS |
208 |
|
209 |
=head2 QUICK OVERVIEW |
210 |
|
211 |
This section simply lists the prototypes most of the functions for |
212 |
quick reference. See the following sections for function-by-function |
213 |
documentation. |
214 |
|
215 |
aio_wd $pathname, $callback->($wd) |
216 |
aio_open $pathname, $flags, $mode, $callback->($fh) |
217 |
aio_close $fh, $callback->($status) |
218 |
aio_seek $fh,$offset,$whence, $callback->($offs) |
219 |
aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
220 |
aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
221 |
aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
222 |
aio_readahead $fh,$offset,$length, $callback->($retval) |
223 |
aio_stat $fh_or_path, $callback->($status) |
224 |
aio_lstat $fh, $callback->($status) |
225 |
aio_statvfs $fh_or_path, $callback->($statvfs) |
226 |
aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
227 |
aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
228 |
aio_chmod $fh_or_path, $mode, $callback->($status) |
229 |
aio_truncate $fh_or_path, $offset, $callback->($status) |
230 |
aio_allocate $fh, $mode, $offset, $len, $callback->($status) |
231 |
aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) |
232 |
aio_unlink $pathname, $callback->($status) |
233 |
aio_mknod $pathname, $mode, $dev, $callback->($status) |
234 |
aio_link $srcpath, $dstpath, $callback->($status) |
235 |
aio_symlink $srcpath, $dstpath, $callback->($status) |
236 |
aio_readlink $pathname, $callback->($link) |
237 |
aio_realpath $pathname, $callback->($path) |
238 |
aio_rename $srcpath, $dstpath, $callback->($status) |
239 |
aio_rename2 $srcpath, $dstpath, $flags, $callback->($status) |
240 |
aio_mkdir $pathname, $mode, $callback->($status) |
241 |
aio_rmdir $pathname, $callback->($status) |
242 |
aio_readdir $pathname, $callback->($entries) |
243 |
aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
244 |
IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST |
245 |
IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN |
246 |
aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) |
247 |
aio_load $pathname, $data, $callback->($status) |
248 |
aio_copy $srcpath, $dstpath, $callback->($status) |
249 |
aio_move $srcpath, $dstpath, $callback->($status) |
250 |
aio_rmtree $pathname, $callback->($status) |
251 |
aio_fcntl $fh, $cmd, $arg, $callback->($status) |
252 |
aio_ioctl $fh, $request, $buf, $callback->($status) |
253 |
aio_sync $callback->($status) |
254 |
aio_syncfs $fh, $callback->($status) |
255 |
aio_fsync $fh, $callback->($status) |
256 |
aio_fdatasync $fh, $callback->($status) |
257 |
aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
258 |
aio_pathsync $pathname, $callback->($status) |
259 |
aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status) |
260 |
aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
261 |
aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
262 |
aio_mlockall $flags, $callback->($status) |
263 |
aio_group $callback->(...) |
264 |
aio_nop $callback->() |
265 |
|
266 |
$prev_pri = aioreq_pri [$pri] |
267 |
aioreq_nice $pri_adjust |
268 |
|
269 |
IO::AIO::poll_wait |
270 |
IO::AIO::poll_cb |
271 |
IO::AIO::poll |
272 |
IO::AIO::flush |
273 |
IO::AIO::max_poll_reqs $nreqs |
274 |
IO::AIO::max_poll_time $seconds |
275 |
IO::AIO::min_parallel $nthreads |
276 |
IO::AIO::max_parallel $nthreads |
277 |
IO::AIO::max_idle $nthreads |
278 |
IO::AIO::idle_timeout $seconds |
279 |
IO::AIO::max_outstanding $maxreqs |
280 |
IO::AIO::nreqs |
281 |
IO::AIO::nready |
282 |
IO::AIO::npending |
283 |
$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL] |
284 |
IO::AIO::min_fdlimit $nfd [EXPERIMENTAL] |
285 |
|
286 |
IO::AIO::sendfile $ofh, $ifh, $offset, $count |
287 |
IO::AIO::fadvise $fh, $offset, $len, $advice |
288 |
IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] |
289 |
IO::AIO::munmap $scalar |
290 |
IO::AIO::madvise $scalar, $offset, $length, $advice |
291 |
IO::AIO::mprotect $scalar, $offset, $length, $protect |
292 |
IO::AIO::munlock $scalar, $offset = 0, $length = undef |
293 |
IO::AIO::munlockall |
294 |
|
295 |
=head2 API NOTES |
296 |
|
297 |
All the C<aio_*> calls are more or less thin wrappers around the syscall |
298 |
with the same name (sans C<aio_>). The arguments are similar or identical, |
299 |
and they all accept an additional (and optional) C<$callback> argument |
300 |
which must be a code reference. This code reference will be called after |
301 |
the syscall has been executed in an asynchronous fashion. The results |
302 |
of the request will be passed as arguments to the callback (and, if an |
303 |
error occured, in C<$!>) - for most requests the syscall return code (e.g. |
304 |
most syscalls return C<-1> on error, unlike perl, which usually delivers |
305 |
"false"). |
306 |
|
307 |
Some requests (such as C<aio_readdir>) pass the actual results and |
308 |
communicate failures by passing C<undef>. |
309 |
|
310 |
All functions expecting a filehandle keep a copy of the filehandle |
311 |
internally until the request has finished. |
312 |
|
313 |
All functions return request objects of type L<IO::AIO::REQ> that allow |
314 |
further manipulation of those requests while they are in-flight. |
315 |
|
316 |
The pathnames you pass to these routines I<should> be absolute. The |
317 |
reason for this is that at the time the request is being executed, the |
318 |
current working directory could have changed. Alternatively, you can |
319 |
make sure that you never change the current working directory anywhere |
320 |
in the program and then use relative paths. You can also take advantage |
321 |
of IO::AIOs working directory abstraction, that lets you specify paths |
322 |
relative to some previously-opened "working directory object" - see the |
323 |
description of the C<IO::AIO::WD> class later in this document. |
324 |
|
325 |
To encode pathnames as octets, either make sure you either: a) always pass |
326 |
in filenames you got from outside (command line, readdir etc.) without |
327 |
tinkering, b) are in your native filesystem encoding, c) use the Encode |
328 |
module and encode your pathnames to the locale (or other) encoding in |
329 |
effect in the user environment, d) use Glib::filename_from_unicode on |
330 |
unicode filenames or e) use something else to ensure your scalar has the |
331 |
correct contents. |
332 |
|
333 |
This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
334 |
handles correctly whether it is set or not. |
335 |
|
336 |
=head2 AIO REQUEST FUNCTIONS |
337 |
|
338 |
=over 4 |
339 |
|
340 |
=item $prev_pri = aioreq_pri [$pri] |
341 |
|
342 |
Returns the priority value that would be used for the next request and, if |
343 |
C<$pri> is given, sets the priority for the next aio request. |
344 |
|
345 |
The default priority is C<0>, the minimum and maximum priorities are C<-4> |
346 |
and C<4>, respectively. Requests with higher priority will be serviced |
347 |
first. |
348 |
|
349 |
The priority will be reset to C<0> after each call to one of the C<aio_*> |
350 |
functions. |
351 |
|
352 |
Example: open a file with low priority, then read something from it with |
353 |
higher priority so the read request is serviced before other low priority |
354 |
open requests (potentially spamming the cache): |
355 |
|
356 |
aioreq_pri -3; |
357 |
aio_open ..., sub { |
358 |
return unless $_[0]; |
359 |
|
360 |
aioreq_pri -2; |
361 |
aio_read $_[0], ..., sub { |
362 |
... |
363 |
}; |
364 |
}; |
365 |
|
366 |
|
367 |
=item aioreq_nice $pri_adjust |
368 |
|
369 |
Similar to C<aioreq_pri>, but subtracts the given value from the current |
370 |
priority, so the effect is cumulative. |
371 |
|
372 |
|
373 |
=item aio_open $pathname, $flags, $mode, $callback->($fh) |
374 |
|
375 |
Asynchronously open or create a file and call the callback with a newly |
376 |
created filehandle for the file (or C<undef> in case of an error). |
377 |
|
378 |
The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
379 |
for an explanation. |
380 |
|
381 |
The C<$flags> argument is a bitmask. See the C<Fcntl> module for a |
382 |
list. They are the same as used by C<sysopen>. |
383 |
|
384 |
Likewise, C<$mode> specifies the mode of the newly created file, if it |
385 |
didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, |
386 |
except that it is mandatory (i.e. use C<0> if you don't create new files, |
387 |
and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified |
388 |
by the umask in effect then the request is being executed, so better never |
389 |
change the umask. |
390 |
|
391 |
Example: |
392 |
|
393 |
aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
394 |
if ($_[0]) { |
395 |
print "open successful, fh is $_[0]\n"; |
396 |
... |
397 |
} else { |
398 |
die "open failed: $!\n"; |
399 |
} |
400 |
}; |
401 |
|
402 |
In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>, |
403 |
C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the |
404 |
following POSIX and non-POSIX constants are available (missing ones on |
405 |
your system are, as usual, C<0>): |
406 |
|
407 |
C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>, |
408 |
C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>, |
409 |
C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>. |
410 |
|
411 |
|
412 |
=item aio_close $fh, $callback->($status) |
413 |
|
414 |
Asynchronously close a file and call the callback with the result |
415 |
code. |
416 |
|
417 |
Unfortunately, you can't do this to perl. Perl I<insists> very strongly on |
418 |
closing the file descriptor associated with the filehandle itself. |
419 |
|
420 |
Therefore, C<aio_close> will not close the filehandle - instead it will |
421 |
use dup2 to overwrite the file descriptor with the write-end of a pipe |
422 |
(the pipe fd will be created on demand and will be cached). |
423 |
|
424 |
Or in other words: the file descriptor will be closed, but it will not be |
425 |
free for reuse until the perl filehandle is closed. |
426 |
|
427 |
=cut |
428 |
|
429 |
=item aio_seek $fh, $offset, $whence, $callback->($offs) |
430 |
|
431 |
Seeks the filehandle to the new C<$offset>, similarly to perl's |
432 |
C<sysseek>. The C<$whence> can use the traditional values (C<0> for |
433 |
C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for |
434 |
C<IO::AIO::SEEK_END>). |
435 |
|
436 |
The resulting absolute offset will be passed to the callback, or C<-1> in |
437 |
case of an error. |
438 |
|
439 |
In theory, the C<$whence> constants could be different than the |
440 |
corresponding values from L<Fcntl>, but perl guarantees they are the same, |
441 |
so don't panic. |
442 |
|
443 |
As a GNU/Linux (and maybe Solaris) extension, also the constants |
444 |
C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they |
445 |
could be found. No guarantees about suitability for use in C<aio_seek> or |
446 |
Perl's C<sysseek> can be made though, although I would naively assume they |
447 |
"just work". |
448 |
|
449 |
=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
450 |
|
451 |
=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
452 |
|
453 |
Reads or writes C<$length> bytes from or to the specified C<$fh> and |
454 |
C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and |
455 |
calls the callback with the actual number of bytes transferred (or -1 on |
456 |
error, just like the syscall). |
457 |
|
458 |
C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to |
459 |
offset plus the actual number of bytes read. |
460 |
|
461 |
If C<$offset> is undefined, then the current file descriptor offset will |
462 |
be used (and updated), otherwise the file descriptor offset will not be |
463 |
changed by these calls. |
464 |
|
465 |
If C<$length> is undefined in C<aio_write>, use the remaining length of |
466 |
C<$data>. |
467 |
|
468 |
If C<$dataoffset> is less than zero, it will be counted from the end of |
469 |
C<$data>. |
470 |
|
471 |
The C<$data> scalar I<MUST NOT> be modified in any way while the request |
472 |
is outstanding. Modifying it can result in segfaults or World War III (if |
473 |
the necessary/optional hardware is installed). |
474 |
|
475 |
Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
476 |
offset C<0> within the scalar: |
477 |
|
478 |
aio_read $fh, 7, 15, $buffer, 0, sub { |
479 |
$_[0] > 0 or die "read error: $!"; |
480 |
print "read $_[0] bytes: <$buffer>\n"; |
481 |
}; |
482 |
|
483 |
|
484 |
=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
485 |
|
486 |
Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts |
487 |
reading at byte offset C<$in_offset>, and starts writing at the current |
488 |
file offset of C<$out_fh>. Because of that, it is not safe to issue more |
489 |
than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each |
490 |
other. The same C<$in_fh> works fine though, as this function does not |
491 |
move or use the file offset of C<$in_fh>. |
492 |
|
493 |
Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than |
494 |
are written, and there is no way to find out how many more bytes have been |
495 |
read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the |
496 |
number of bytes written to C<$out_fh>. Only if the result value equals |
497 |
C<$length> one can assume that C<$length> bytes have been read. |
498 |
|
499 |
Unlike with other C<aio_> functions, it makes a lot of sense to use |
500 |
C<aio_sendfile> on non-blocking sockets, as long as one end (typically |
501 |
the C<$in_fh>) is a file - the file I/O will then be asynchronous, while |
502 |
the socket I/O will be non-blocking. Note, however, that you can run |
503 |
into a trap where C<aio_sendfile> reads some data with readahead, then |
504 |
fails to write all data, and when the socket is ready the next time, the |
505 |
data in the cache is already lost, forcing C<aio_sendfile> to again hit |
506 |
the disk. Explicit C<aio_read> + C<aio_write> let's you better control |
507 |
resource usage. |
508 |
|
509 |
This call tries to make use of a native C<sendfile>-like syscall to |
510 |
provide zero-copy operation. For this to work, C<$out_fh> should refer to |
511 |
a socket, and C<$in_fh> should refer to an mmap'able file. |
512 |
|
513 |
If a native sendfile cannot be found or it fails with C<ENOSYS>, |
514 |
C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or |
515 |
C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any |
516 |
type of filehandle regardless of the limitations of the operating system. |
517 |
|
518 |
As native sendfile syscalls (as practically any non-POSIX interface hacked |
519 |
together in a hurry to improve benchmark numbers) tend to be rather buggy |
520 |
on many systems, this implementation tries to work around some known bugs |
521 |
in Linux and FreeBSD kernels (probably others, too), but that might fail, |
522 |
so you really really should check the return value of C<aio_sendfile> - |
523 |
fewer bytes than expected might have been transferred. |
524 |
|
525 |
|
526 |
=item aio_readahead $fh,$offset,$length, $callback->($retval) |
527 |
|
528 |
C<aio_readahead> populates the page cache with data from a file so that |
529 |
subsequent reads from that file will not block on disk I/O. The C<$offset> |
530 |
argument specifies the starting point from which data is to be read and |
531 |
C<$length> specifies the number of bytes to be read. I/O is performed in |
532 |
whole pages, so that offset is effectively rounded down to a page boundary |
533 |
and bytes are read up to the next page boundary greater than or equal to |
534 |
(off-set+length). C<aio_readahead> does not read beyond the end of the |
535 |
file. The current file offset of the file is left unchanged. |
536 |
|
537 |
If that syscall doesn't exist (likely if your kernel isn't Linux) it will |
538 |
be emulated by simply reading the data, which would have a similar effect. |
539 |
|
540 |
|
541 |
=item aio_stat $fh_or_path, $callback->($status) |
542 |
|
543 |
=item aio_lstat $fh, $callback->($status) |
544 |
|
545 |
Works like perl's C<stat> or C<lstat> in void context. The callback will |
546 |
be called after the stat and the results will be available using C<stat _> |
547 |
or C<-s _> etc... |
548 |
|
549 |
The pathname passed to C<aio_stat> must be absolute. See API NOTES, above, |
550 |
for an explanation. |
551 |
|
552 |
Currently, the stats are always 64-bit-stats, i.e. instead of returning an |
553 |
error when stat'ing a large file, the results will be silently truncated |
554 |
unless perl itself is compiled with large file support. |
555 |
|
556 |
To help interpret the mode and dev/rdev stat values, IO::AIO offers the |
557 |
following constants and functions (if not implemented, the constants will |
558 |
be C<0> and the functions will either C<croak> or fall back on traditional |
559 |
behaviour). |
560 |
|
561 |
C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>, |
562 |
C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>, |
563 |
C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>. |
564 |
|
565 |
Example: Print the length of F</etc/passwd>: |
566 |
|
567 |
aio_stat "/etc/passwd", sub { |
568 |
$_[0] and die "stat failed: $!"; |
569 |
print "size is ", -s _, "\n"; |
570 |
}; |
571 |
|
572 |
|
573 |
=item aio_statvfs $fh_or_path, $callback->($statvfs) |
574 |
|
575 |
Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on |
576 |
whether a file handle or path was passed. |
577 |
|
578 |
On success, the callback is passed a hash reference with the following |
579 |
members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>, |
580 |
C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef> |
581 |
is passed. |
582 |
|
583 |
The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and |
584 |
C<ST_NOSUID>. |
585 |
|
586 |
The following non-POSIX IO::AIO::ST_* flag masks are defined to |
587 |
their correct value when available, or to C<0> on systems that do |
588 |
not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>, |
589 |
C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>, |
590 |
C<ST_NODIRATIME> and C<ST_RELATIME>. |
591 |
|
592 |
Example: stat C</wd> and dump out the data if successful. |
593 |
|
594 |
aio_statvfs "/wd", sub { |
595 |
my $f = $_[0] |
596 |
or die "statvfs: $!"; |
597 |
|
598 |
use Data::Dumper; |
599 |
say Dumper $f; |
600 |
}; |
601 |
|
602 |
# result: |
603 |
{ |
604 |
bsize => 1024, |
605 |
bfree => 4333064312, |
606 |
blocks => 10253828096, |
607 |
files => 2050765568, |
608 |
flag => 4096, |
609 |
favail => 2042092649, |
610 |
bavail => 4333064312, |
611 |
ffree => 2042092649, |
612 |
namemax => 255, |
613 |
frsize => 1024, |
614 |
fsid => 1810 |
615 |
} |
616 |
|
617 |
=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
618 |
|
619 |
Works like perl's C<utime> function (including the special case of $atime |
620 |
and $mtime being undef). Fractional times are supported if the underlying |
621 |
syscalls support them. |
622 |
|
623 |
When called with a pathname, uses utimes(2) if available, otherwise |
624 |
utime(2). If called on a file descriptor, uses futimes(2) if available, |
625 |
otherwise returns ENOSYS, so this is not portable. |
626 |
|
627 |
Examples: |
628 |
|
629 |
# set atime and mtime to current time (basically touch(1)): |
630 |
aio_utime "path", undef, undef; |
631 |
# set atime to current time and mtime to beginning of the epoch: |
632 |
aio_utime "path", time, undef; # undef==0 |
633 |
|
634 |
|
635 |
=item aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
636 |
|
637 |
Works like perl's C<chown> function, except that C<undef> for either $uid |
638 |
or $gid is being interpreted as "do not change" (but -1 can also be used). |
639 |
|
640 |
Examples: |
641 |
|
642 |
# same as "chown root path" in the shell: |
643 |
aio_chown "path", 0, -1; |
644 |
# same as above: |
645 |
aio_chown "path", 0, undef; |
646 |
|
647 |
|
648 |
=item aio_truncate $fh_or_path, $offset, $callback->($status) |
649 |
|
650 |
Works like truncate(2) or ftruncate(2). |
651 |
|
652 |
|
653 |
=item aio_allocate $fh, $mode, $offset, $len, $callback->($status) |
654 |
|
655 |
Allocates or frees disk space according to the C<$mode> argument. See the |
656 |
linux C<fallocate> documentation for details. |
657 |
|
658 |
C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate |
659 |
space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>, |
660 |
to deallocate a file range. |
661 |
|
662 |
IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range |
663 |
(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range, |
664 |
C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE> |
665 |
to unshare shared blocks (see your L<fallocate(2)> manpage). |
666 |
|
667 |
The file system block size used by C<fallocate> is presumably the |
668 |
C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes |
669 |
can dictate other limitations. |
670 |
|
671 |
If C<fallocate> isn't available or cannot be emulated (currently no |
672 |
emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>. |
673 |
|
674 |
|
675 |
=item aio_chmod $fh_or_path, $mode, $callback->($status) |
676 |
|
677 |
Works like perl's C<chmod> function. |
678 |
|
679 |
|
680 |
=item aio_unlink $pathname, $callback->($status) |
681 |
|
682 |
Asynchronously unlink (delete) a file and call the callback with the |
683 |
result code. |
684 |
|
685 |
|
686 |
=item aio_mknod $pathname, $mode, $dev, $callback->($status) |
687 |
|
688 |
[EXPERIMENTAL] |
689 |
|
690 |
Asynchronously create a device node (or fifo). See mknod(2). |
691 |
|
692 |
The only (POSIX-) portable way of calling this function is: |
693 |
|
694 |
aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
695 |
|
696 |
See C<aio_stat> for info about some potentially helpful extra constants |
697 |
and functions. |
698 |
|
699 |
=item aio_link $srcpath, $dstpath, $callback->($status) |
700 |
|
701 |
Asynchronously create a new link to the existing object at C<$srcpath> at |
702 |
the path C<$dstpath> and call the callback with the result code. |
703 |
|
704 |
|
705 |
=item aio_symlink $srcpath, $dstpath, $callback->($status) |
706 |
|
707 |
Asynchronously create a new symbolic link to the existing object at C<$srcpath> at |
708 |
the path C<$dstpath> and call the callback with the result code. |
709 |
|
710 |
|
711 |
=item aio_readlink $pathname, $callback->($link) |
712 |
|
713 |
Asynchronously read the symlink specified by C<$path> and pass it to |
714 |
the callback. If an error occurs, nothing or undef gets passed to the |
715 |
callback. |
716 |
|
717 |
|
718 |
=item aio_realpath $pathname, $callback->($path) |
719 |
|
720 |
Asynchronously make the path absolute and resolve any symlinks in |
721 |
C<$path>. The resulting path only consists of directories (same as |
722 |
L<Cwd::realpath>). |
723 |
|
724 |
This request can be used to get the absolute path of the current working |
725 |
directory by passing it a path of F<.> (a single dot). |
726 |
|
727 |
|
728 |
=item aio_rename $srcpath, $dstpath, $callback->($status) |
729 |
|
730 |
Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as |
731 |
rename(2) and call the callback with the result code. |
732 |
|
733 |
On systems that support the AIO::WD working directory abstraction |
734 |
natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead |
735 |
of failing, C<rename> is called on the absolute path of C<$wd>. |
736 |
|
737 |
|
738 |
=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status) |
739 |
|
740 |
Basically a version of C<aio_rename> with an additional C<$flags> |
741 |
argument. Calling this with C<$flags=0> is the same as calling |
742 |
C<aio_rename>. |
743 |
|
744 |
Non-zero flags are currently only supported on GNU/Linux systems that |
745 |
support renameat2. Other systems fail with C<ENOSYS> in this case. |
746 |
|
747 |
The following constants are available (missing ones are, as usual C<0>), |
748 |
see renameat2(2) for details: |
749 |
|
750 |
C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE> |
751 |
and C<IO::AIO::RENAME_WHITEOUT>. |
752 |
|
753 |
|
754 |
=item aio_mkdir $pathname, $mode, $callback->($status) |
755 |
|
756 |
Asynchronously mkdir (create) a directory and call the callback with |
757 |
the result code. C<$mode> will be modified by the umask at the time the |
758 |
request is executed, so do not change your umask. |
759 |
|
760 |
|
761 |
=item aio_rmdir $pathname, $callback->($status) |
762 |
|
763 |
Asynchronously rmdir (delete) a directory and call the callback with the |
764 |
result code. |
765 |
|
766 |
On systems that support the AIO::WD working directory abstraction |
767 |
natively, the case C<[$wd, "."]> is specialcased - instead of failing, |
768 |
C<rmdir> is called on the absolute path of C<$wd>. |
769 |
|
770 |
|
771 |
=item aio_readdir $pathname, $callback->($entries) |
772 |
|
773 |
Unlike the POSIX call of the same name, C<aio_readdir> reads an entire |
774 |
directory (i.e. opendir + readdir + closedir). The entries will not be |
775 |
sorted, and will B<NOT> include the C<.> and C<..> entries. |
776 |
|
777 |
The callback is passed a single argument which is either C<undef> or an |
778 |
array-ref with the filenames. |
779 |
|
780 |
|
781 |
=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
782 |
|
783 |
Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to |
784 |
tune behaviour and output format. In case of an error, C<$entries> will be |
785 |
C<undef>. |
786 |
|
787 |
The flags are a combination of the following constants, ORed together (the |
788 |
flags will also be passed to the callback, possibly modified): |
789 |
|
790 |
=over 4 |
791 |
|
792 |
=item IO::AIO::READDIR_DENTS |
793 |
|
794 |
When this flag is off, then the callback gets an arrayref consisting of |
795 |
names only (as with C<aio_readdir>), otherwise it gets an arrayref with |
796 |
C<[$name, $type, $inode]> arrayrefs, each describing a single directory |
797 |
entry in more detail. |
798 |
|
799 |
C<$name> is the name of the entry. |
800 |
|
801 |
C<$type> is one of the C<IO::AIO::DT_xxx> constants: |
802 |
|
803 |
C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>, |
804 |
C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>, |
805 |
C<IO::AIO::DT_WHT>. |
806 |
|
807 |
C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to |
808 |
know, you have to run stat yourself. Also, for speed reasons, the C<$type> |
809 |
scalars are read-only: you can not modify them. |
810 |
|
811 |
C<$inode> is the inode number (which might not be exact on systems with 64 |
812 |
bit inode numbers and 32 bit perls). This field has unspecified content on |
813 |
systems that do not deliver the inode information. |
814 |
|
815 |
=item IO::AIO::READDIR_DIRS_FIRST |
816 |
|
817 |
When this flag is set, then the names will be returned in an order where |
818 |
likely directories come first, in optimal stat order. This is useful when |
819 |
you need to quickly find directories, or you want to find all directories |
820 |
while avoiding to stat() each entry. |
821 |
|
822 |
If the system returns type information in readdir, then this is used |
823 |
to find directories directly. Otherwise, likely directories are names |
824 |
beginning with ".", or otherwise names with no dots, of which names with |
825 |
short names are tried first. |
826 |
|
827 |
=item IO::AIO::READDIR_STAT_ORDER |
828 |
|
829 |
When this flag is set, then the names will be returned in an order |
830 |
suitable for stat()'ing each one. That is, when you plan to stat() |
831 |
all files in the given directory, then the returned order will likely |
832 |
be fastest. |
833 |
|
834 |
If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then |
835 |
the likely dirs come first, resulting in a less optimal stat order. |
836 |
|
837 |
=item IO::AIO::READDIR_FOUND_UNKNOWN |
838 |
|
839 |
This flag should not be set when calling C<aio_readdirx>. Instead, it |
840 |
is being set by C<aio_readdirx>, when any of the C<$type>'s found were |
841 |
C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all |
842 |
C<$type>'s are known, which can be used to speed up some algorithms. |
843 |
|
844 |
=back |
845 |
|
846 |
|
847 |
=item aio_slurp $pathname, $offset, $length, $data, $callback->($status) |
848 |
|
849 |
Opens, reads and closes the given file. The data is put into C<$data>, |
850 |
which is resized as required. |
851 |
|
852 |
If C<$offset> is negative, then it is counted from the end of the file. |
853 |
|
854 |
If C<$length> is zero, then the remaining length of the file is |
855 |
used. Also, in this case, the same limitations to modifying C<$data> apply |
856 |
as when IO::AIO::mmap is used, i.e. it must only be modified in-place |
857 |
with C<substr>. If the size of the file is known, specifying a non-zero |
858 |
C<$length> results in a performance advantage. |
859 |
|
860 |
This request is similar to the older C<aio_load> request, but since it is |
861 |
a single request, it might be more efficient to use. |
862 |
|
863 |
Example: load F</etc/passwd> into C<$passwd>. |
864 |
|
865 |
my $passwd; |
866 |
aio_slurp "/etc/passwd", 0, 0, $passwd, sub { |
867 |
$_[0] >= 0 |
868 |
or die "/etc/passwd: $!\n"; |
869 |
|
870 |
printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd; |
871 |
print $passwd; |
872 |
}; |
873 |
IO::AIO::flush; |
874 |
|
875 |
|
876 |
=item aio_load $pathname, $data, $callback->($status) |
877 |
|
878 |
This is a composite request that tries to fully load the given file into |
879 |
memory. Status is the same as with aio_read. |
880 |
|
881 |
Using C<aio_slurp> might be more efficient, as it is a single request. |
882 |
|
883 |
=cut |
884 |
|
885 |
sub aio_load($$;$) { |
886 |
my ($path, undef, $cb) = @_; |
887 |
my $data = \$_[1]; |
888 |
|
889 |
my $pri = aioreq_pri; |
890 |
my $grp = aio_group $cb; |
891 |
|
892 |
aioreq_pri $pri; |
893 |
add $grp aio_open $path, O_RDONLY, 0, sub { |
894 |
my $fh = shift |
895 |
or return $grp->result (-1); |
896 |
|
897 |
aioreq_pri $pri; |
898 |
add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub { |
899 |
$grp->result ($_[0]); |
900 |
}; |
901 |
}; |
902 |
|
903 |
$grp |
904 |
} |
905 |
|
906 |
=item aio_copy $srcpath, $dstpath, $callback->($status) |
907 |
|
908 |
Try to copy the I<file> (directories not supported as either source or |
909 |
destination) from C<$srcpath> to C<$dstpath> and call the callback with |
910 |
a status of C<0> (ok) or C<-1> (error, see C<$!>). |
911 |
|
912 |
Existing destination files will be truncated. |
913 |
|
914 |
This is a composite request that creates the destination file with |
915 |
mode 0200 and copies the contents of the source file into it using |
916 |
C<aio_sendfile>, followed by restoring atime, mtime, access mode and |
917 |
uid/gid, in that order. |
918 |
|
919 |
If an error occurs, the partial destination file will be unlinked, if |
920 |
possible, except when setting atime, mtime, access mode and uid/gid, where |
921 |
errors are being ignored. |
922 |
|
923 |
=cut |
924 |
|
925 |
sub aio_copy($$;$) { |
926 |
my ($src, $dst, $cb) = @_; |
927 |
|
928 |
my $pri = aioreq_pri; |
929 |
my $grp = aio_group $cb; |
930 |
|
931 |
aioreq_pri $pri; |
932 |
add $grp aio_open $src, O_RDONLY, 0, sub { |
933 |
if (my $src_fh = $_[0]) { |
934 |
my @stat = stat $src_fh; # hmm, might block over nfs? |
935 |
|
936 |
aioreq_pri $pri; |
937 |
add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { |
938 |
if (my $dst_fh = $_[0]) { |
939 |
aioreq_pri $pri; |
940 |
add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { |
941 |
if ($_[0] == $stat[7]) { |
942 |
$grp->result (0); |
943 |
close $src_fh; |
944 |
|
945 |
my $ch = sub { |
946 |
aioreq_pri $pri; |
947 |
add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub { |
948 |
aioreq_pri $pri; |
949 |
add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub { |
950 |
aioreq_pri $pri; |
951 |
add $grp aio_close $dst_fh; |
952 |
} |
953 |
}; |
954 |
}; |
955 |
|
956 |
aioreq_pri $pri; |
957 |
add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub { |
958 |
if ($_[0] < 0 && $! == ENOSYS) { |
959 |
aioreq_pri $pri; |
960 |
add $grp aio_utime $dst, $stat[8], $stat[9], $ch; |
961 |
} else { |
962 |
$ch->(); |
963 |
} |
964 |
}; |
965 |
} else { |
966 |
$grp->result (-1); |
967 |
close $src_fh; |
968 |
close $dst_fh; |
969 |
|
970 |
aioreq $pri; |
971 |
add $grp aio_unlink $dst; |
972 |
} |
973 |
}; |
974 |
} else { |
975 |
$grp->result (-1); |
976 |
} |
977 |
}, |
978 |
|
979 |
} else { |
980 |
$grp->result (-1); |
981 |
} |
982 |
}; |
983 |
|
984 |
$grp |
985 |
} |
986 |
|
987 |
=item aio_move $srcpath, $dstpath, $callback->($status) |
988 |
|
989 |
Try to move the I<file> (directories not supported as either source or |
990 |
destination) from C<$srcpath> to C<$dstpath> and call the callback with |
991 |
a status of C<0> (ok) or C<-1> (error, see C<$!>). |
992 |
|
993 |
This is a composite request that tries to rename(2) the file first; if |
994 |
rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if |
995 |
that is successful, unlinks the C<$srcpath>. |
996 |
|
997 |
=cut |
998 |
|
999 |
sub aio_move($$;$) { |
1000 |
my ($src, $dst, $cb) = @_; |
1001 |
|
1002 |
my $pri = aioreq_pri; |
1003 |
my $grp = aio_group $cb; |
1004 |
|
1005 |
aioreq_pri $pri; |
1006 |
add $grp aio_rename $src, $dst, sub { |
1007 |
if ($_[0] && $! == EXDEV) { |
1008 |
aioreq_pri $pri; |
1009 |
add $grp aio_copy $src, $dst, sub { |
1010 |
$grp->result ($_[0]); |
1011 |
|
1012 |
unless ($_[0]) { |
1013 |
aioreq_pri $pri; |
1014 |
add $grp aio_unlink $src; |
1015 |
} |
1016 |
}; |
1017 |
} else { |
1018 |
$grp->result ($_[0]); |
1019 |
} |
1020 |
}; |
1021 |
|
1022 |
$grp |
1023 |
} |
1024 |
|
1025 |
=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) |
1026 |
|
1027 |
Scans a directory (similar to C<aio_readdir>) but additionally tries to |
1028 |
efficiently separate the entries of directory C<$path> into two sets of |
1029 |
names, directories you can recurse into (directories), and ones you cannot |
1030 |
recurse into (everything else, including symlinks to directories). |
1031 |
|
1032 |
C<aio_scandir> is a composite request that generates many sub requests. |
1033 |
C<$maxreq> specifies the maximum number of outstanding aio requests that |
1034 |
this function generates. If it is C<< <= 0 >>, then a suitable default |
1035 |
will be chosen (currently 4). |
1036 |
|
1037 |
On error, the callback is called without arguments, otherwise it receives |
1038 |
two array-refs with path-relative entry names. |
1039 |
|
1040 |
Example: |
1041 |
|
1042 |
aio_scandir $dir, 0, sub { |
1043 |
my ($dirs, $nondirs) = @_; |
1044 |
print "real directories: @$dirs\n"; |
1045 |
print "everything else: @$nondirs\n"; |
1046 |
}; |
1047 |
|
1048 |
Implementation notes. |
1049 |
|
1050 |
The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. |
1051 |
|
1052 |
If readdir returns file type information, then this is used directly to |
1053 |
find directories. |
1054 |
|
1055 |
Otherwise, after reading the directory, the modification time, size etc. |
1056 |
of the directory before and after the readdir is checked, and if they |
1057 |
match (and isn't the current time), the link count will be used to decide |
1058 |
how many entries are directories (if >= 2). Otherwise, no knowledge of the |
1059 |
number of subdirectories will be assumed. |
1060 |
|
1061 |
Then entries will be sorted into likely directories a non-initial dot |
1062 |
currently) and likely non-directories (see C<aio_readdirx>). Then every |
1063 |
entry plus an appended C</.> will be C<stat>'ed, likely directories first, |
1064 |
in order of their inode numbers. If that succeeds, it assumes that the |
1065 |
entry is a directory or a symlink to directory (which will be checked |
1066 |
separately). This is often faster than stat'ing the entry itself because |
1067 |
filesystems might detect the type of the entry without reading the inode |
1068 |
data (e.g. ext2fs filetype feature), even on systems that cannot return |
1069 |
the filetype information on readdir. |
1070 |
|
1071 |
If the known number of directories (link count - 2) has been reached, the |
1072 |
rest of the entries is assumed to be non-directories. |
1073 |
|
1074 |
This only works with certainty on POSIX (= UNIX) filesystems, which |
1075 |
fortunately are the vast majority of filesystems around. |
1076 |
|
1077 |
It will also likely work on non-POSIX filesystems with reduced efficiency |
1078 |
as those tend to return 0 or 1 as link counts, which disables the |
1079 |
directory counting heuristic. |
1080 |
|
1081 |
=cut |
1082 |
|
1083 |
sub aio_scandir($$;$) { |
1084 |
my ($path, $maxreq, $cb) = @_; |
1085 |
|
1086 |
my $pri = aioreq_pri; |
1087 |
|
1088 |
my $grp = aio_group $cb; |
1089 |
|
1090 |
$maxreq = 4 if $maxreq <= 0; |
1091 |
|
1092 |
# get a wd object |
1093 |
aioreq_pri $pri; |
1094 |
add $grp aio_wd $path, sub { |
1095 |
$_[0] |
1096 |
or return $grp->result (); |
1097 |
|
1098 |
my $wd = [shift, "."]; |
1099 |
|
1100 |
# stat once |
1101 |
aioreq_pri $pri; |
1102 |
add $grp aio_stat $wd, sub { |
1103 |
return $grp->result () if $_[0]; |
1104 |
my $now = time; |
1105 |
my $hash1 = join ":", (stat _)[0,1,3,7,9]; |
1106 |
|
1107 |
# read the directory entries |
1108 |
aioreq_pri $pri; |
1109 |
add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub { |
1110 |
my $entries = shift |
1111 |
or return $grp->result (); |
1112 |
|
1113 |
# stat the dir another time |
1114 |
aioreq_pri $pri; |
1115 |
add $grp aio_stat $wd, sub { |
1116 |
my $hash2 = join ":", (stat _)[0,1,3,7,9]; |
1117 |
|
1118 |
my $ndirs; |
1119 |
|
1120 |
# take the slow route if anything looks fishy |
1121 |
if ($hash1 ne $hash2 or (stat _)[9] == $now) { |
1122 |
$ndirs = -1; |
1123 |
} else { |
1124 |
# if nlink == 2, we are finished |
1125 |
# for non-posix-fs's, we rely on nlink < 2 |
1126 |
$ndirs = (stat _)[3] - 2 |
1127 |
or return $grp->result ([], $entries); |
1128 |
} |
1129 |
|
1130 |
my (@dirs, @nondirs); |
1131 |
|
1132 |
my $statgrp = add $grp aio_group sub { |
1133 |
$grp->result (\@dirs, \@nondirs); |
1134 |
}; |
1135 |
|
1136 |
limit $statgrp $maxreq; |
1137 |
feed $statgrp sub { |
1138 |
return unless @$entries; |
1139 |
my $entry = shift @$entries; |
1140 |
|
1141 |
aioreq_pri $pri; |
1142 |
$wd->[1] = "$entry/."; |
1143 |
add $statgrp aio_stat $wd, sub { |
1144 |
if ($_[0] < 0) { |
1145 |
push @nondirs, $entry; |
1146 |
} else { |
1147 |
# need to check for real directory |
1148 |
aioreq_pri $pri; |
1149 |
$wd->[1] = $entry; |
1150 |
add $statgrp aio_lstat $wd, sub { |
1151 |
if (-d _) { |
1152 |
push @dirs, $entry; |
1153 |
|
1154 |
unless (--$ndirs) { |
1155 |
push @nondirs, @$entries; |
1156 |
feed $statgrp; |
1157 |
} |
1158 |
} else { |
1159 |
push @nondirs, $entry; |
1160 |
} |
1161 |
} |
1162 |
} |
1163 |
}; |
1164 |
}; |
1165 |
}; |
1166 |
}; |
1167 |
}; |
1168 |
}; |
1169 |
|
1170 |
$grp |
1171 |
} |
1172 |
|
1173 |
=item aio_rmtree $pathname, $callback->($status) |
1174 |
|
1175 |
Delete a directory tree starting (and including) C<$path>, return the |
1176 |
status of the final C<rmdir> only. This is a composite request that |
1177 |
uses C<aio_scandir> to recurse into and rmdir directories, and unlink |
1178 |
everything else. |
1179 |
|
1180 |
=cut |
1181 |
|
1182 |
sub aio_rmtree; |
1183 |
sub aio_rmtree($;$) { |
1184 |
my ($path, $cb) = @_; |
1185 |
|
1186 |
my $pri = aioreq_pri; |
1187 |
my $grp = aio_group $cb; |
1188 |
|
1189 |
aioreq_pri $pri; |
1190 |
add $grp aio_scandir $path, 0, sub { |
1191 |
my ($dirs, $nondirs) = @_; |
1192 |
|
1193 |
my $dirgrp = aio_group sub { |
1194 |
add $grp aio_rmdir $path, sub { |
1195 |
$grp->result ($_[0]); |
1196 |
}; |
1197 |
}; |
1198 |
|
1199 |
(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs; |
1200 |
(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs; |
1201 |
|
1202 |
add $grp $dirgrp; |
1203 |
}; |
1204 |
|
1205 |
$grp |
1206 |
} |
1207 |
|
1208 |
=item aio_fcntl $fh, $cmd, $arg, $callback->($status) |
1209 |
|
1210 |
=item aio_ioctl $fh, $request, $buf, $callback->($status) |
1211 |
|
1212 |
These work just like the C<fcntl> and C<ioctl> built-in functions, except |
1213 |
they execute asynchronously and pass the return value to the callback. |
1214 |
|
1215 |
Both calls can be used for a lot of things, some of which make more sense |
1216 |
to run asynchronously in their own thread, while some others make less |
1217 |
sense. For example, calls that block waiting for external events, such |
1218 |
as locking, will also lock down an I/O thread while it is waiting, which |
1219 |
can deadlock the whole I/O system. At the same time, there might be no |
1220 |
alternative to using a thread to wait. |
1221 |
|
1222 |
So in general, you should only use these calls for things that do |
1223 |
(filesystem) I/O, not for things that wait for other events (network, |
1224 |
other processes), although if you are careful and know what you are doing, |
1225 |
you still can. |
1226 |
|
1227 |
The following constants are available (missing ones are, as usual C<0>): |
1228 |
|
1229 |
C<F_DUPFD_CLOEXEC>, |
1230 |
|
1231 |
C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>, |
1232 |
|
1233 |
C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>. |
1234 |
|
1235 |
C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>, |
1236 |
C<FS_IOC_FIEMAP>. |
1237 |
|
1238 |
C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>, |
1239 |
C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>. |
1240 |
|
1241 |
C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>, |
1242 |
C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>, |
1243 |
C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>, |
1244 |
C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>, |
1245 |
C<FS_FL_USER_MODIFIABLE>. |
1246 |
|
1247 |
C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>, |
1248 |
C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>, |
1249 |
C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>, |
1250 |
C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>, |
1251 |
|
1252 |
=item aio_sync $callback->($status) |
1253 |
|
1254 |
Asynchronously call sync and call the callback when finished. |
1255 |
|
1256 |
=item aio_fsync $fh, $callback->($status) |
1257 |
|
1258 |
Asynchronously call fsync on the given filehandle and call the callback |
1259 |
with the fsync result code. |
1260 |
|
1261 |
=item aio_fdatasync $fh, $callback->($status) |
1262 |
|
1263 |
Asynchronously call fdatasync on the given filehandle and call the |
1264 |
callback with the fdatasync result code. |
1265 |
|
1266 |
If this call isn't available because your OS lacks it or it couldn't be |
1267 |
detected, it will be emulated by calling C<fsync> instead. |
1268 |
|
1269 |
=item aio_syncfs $fh, $callback->($status) |
1270 |
|
1271 |
Asynchronously call the syncfs syscall to sync the filesystem associated |
1272 |
to the given filehandle and call the callback with the syncfs result |
1273 |
code. If syncfs is not available, calls sync(), but returns C<-1> and sets |
1274 |
errno to C<ENOSYS> nevertheless. |
1275 |
|
1276 |
=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
1277 |
|
1278 |
Sync the data portion of the file specified by C<$offset> and C<$length> |
1279 |
to disk (but NOT the metadata), by calling the Linux-specific |
1280 |
sync_file_range call. If sync_file_range is not available or it returns |
1281 |
ENOSYS, then fdatasync or fsync is being substituted. |
1282 |
|
1283 |
C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, |
1284 |
C<IO::AIO::SYNC_FILE_RANGE_WRITE> and |
1285 |
C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range |
1286 |
manpage for details. |
1287 |
|
1288 |
=item aio_pathsync $pathname, $callback->($status) |
1289 |
|
1290 |
This request tries to open, fsync and close the given path. This is a |
1291 |
composite request intended to sync directories after directory operations |
1292 |
(E.g. rename). This might not work on all operating systems or have any |
1293 |
specific effect, but usually it makes sure that directory changes get |
1294 |
written to disc. It works for anything that can be opened for read-only, |
1295 |
not just directories. |
1296 |
|
1297 |
Future versions of this function might fall back to other methods when |
1298 |
C<fsync> on the directory fails (such as calling C<sync>). |
1299 |
|
1300 |
Passes C<0> when everything went ok, and C<-1> on error. |
1301 |
|
1302 |
=cut |
1303 |
|
1304 |
sub aio_pathsync($;$) { |
1305 |
my ($path, $cb) = @_; |
1306 |
|
1307 |
my $pri = aioreq_pri; |
1308 |
my $grp = aio_group $cb; |
1309 |
|
1310 |
aioreq_pri $pri; |
1311 |
add $grp aio_open $path, O_RDONLY, 0, sub { |
1312 |
my ($fh) = @_; |
1313 |
if ($fh) { |
1314 |
aioreq_pri $pri; |
1315 |
add $grp aio_fsync $fh, sub { |
1316 |
$grp->result ($_[0]); |
1317 |
|
1318 |
aioreq_pri $pri; |
1319 |
add $grp aio_close $fh; |
1320 |
}; |
1321 |
} else { |
1322 |
$grp->result (-1); |
1323 |
} |
1324 |
}; |
1325 |
|
1326 |
$grp |
1327 |
} |
1328 |
|
1329 |
=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status) |
1330 |
|
1331 |
This is a rather advanced IO::AIO call, which only works on mmap(2)ed |
1332 |
scalars (see the C<IO::AIO::mmap> function, although it also works on data |
1333 |
scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the |
1334 |
scalar must only be modified in-place while an aio operation is pending on |
1335 |
it). |
1336 |
|
1337 |
It calls the C<msync> function of your OS, if available, with the memory |
1338 |
area starting at C<$offset> in the string and ending C<$length> bytes |
1339 |
later. If C<$length> is negative, counts from the end, and if C<$length> |
1340 |
is C<undef>, then it goes till the end of the string. The flags can be |
1341 |
either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional |
1342 |
C<IO::AIO::MS_INVALIDATE>. |
1343 |
|
1344 |
=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
1345 |
|
1346 |
This is a rather advanced IO::AIO call, which works best on mmap(2)ed |
1347 |
scalars. |
1348 |
|
1349 |
It touches (reads or writes) all memory pages in the specified |
1350 |
range inside the scalar. All caveats and parameters are the same |
1351 |
as for C<aio_msync>, above, except for flags, which must be either |
1352 |
C<0> (which reads all pages and ensures they are instantiated) or |
1353 |
C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and |
1354 |
writing an octet from it, which dirties the page). |
1355 |
|
1356 |
=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
1357 |
|
1358 |
This is a rather advanced IO::AIO call, which works best on mmap(2)ed |
1359 |
scalars. |
1360 |
|
1361 |
It reads in all the pages of the underlying storage into memory (if any) |
1362 |
and locks them, so they are not getting swapped/paged out or removed. |
1363 |
|
1364 |
If C<$length> is undefined, then the scalar will be locked till the end. |
1365 |
|
1366 |
On systems that do not implement C<mlock>, this function returns C<-1> |
1367 |
and sets errno to C<ENOSYS>. |
1368 |
|
1369 |
Note that the corresponding C<munlock> is synchronous and is |
1370 |
documented under L<MISCELLANEOUS FUNCTIONS>. |
1371 |
|
1372 |
Example: open a file, mmap and mlock it - both will be undone when |
1373 |
C<$data> gets destroyed. |
1374 |
|
1375 |
open my $fh, "<", $path or die "$path: $!"; |
1376 |
my $data; |
1377 |
IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; |
1378 |
aio_mlock $data; # mlock in background |
1379 |
|
1380 |
=item aio_mlockall $flags, $callback->($status) |
1381 |
|
1382 |
Calls the C<mlockall> function with the given C<$flags> (a combination of |
1383 |
C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>). |
1384 |
|
1385 |
On systems that do not implement C<mlockall>, this function returns C<-1> |
1386 |
and sets errno to C<ENOSYS>. |
1387 |
|
1388 |
Note that the corresponding C<munlockall> is synchronous and is |
1389 |
documented under L<MISCELLANEOUS FUNCTIONS>. |
1390 |
|
1391 |
Example: asynchronously lock all current and future pages into memory. |
1392 |
|
1393 |
aio_mlockall IO::AIO::MCL_FUTURE; |
1394 |
|
1395 |
=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) |
1396 |
|
1397 |
Queries the extents of the given file (by calling the Linux C<FIEMAP> |
1398 |
ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If |
1399 |
the ioctl is not available on your OS, then this request will fail with |
1400 |
C<ENOSYS>. |
1401 |
|
1402 |
C<$start> is the starting offset to query extents for, C<$length> is the |
1403 |
size of the range to query - if it is C<undef>, then the whole file will |
1404 |
be queried. |
1405 |
|
1406 |
C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or |
1407 |
C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also |
1408 |
exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query |
1409 |
the data portion. |
1410 |
|
1411 |
C<$count> is the maximum number of extent records to return. If it is |
1412 |
C<undef>, then IO::AIO queries all extents of the range. As a very special |
1413 |
case, if it is C<0>, then the callback receives the number of extents |
1414 |
instead of the extents themselves (which is unreliable, see below). |
1415 |
|
1416 |
If an error occurs, the callback receives no arguments. The special |
1417 |
C<errno> value C<IO::AIO::EBADR> is available to test for flag errors. |
1418 |
|
1419 |
Otherwise, the callback receives an array reference with extent |
1420 |
structures. Each extent structure is an array reference itself, with the |
1421 |
following members: |
1422 |
|
1423 |
[$logical, $physical, $length, $flags] |
1424 |
|
1425 |
Flags is any combination of the following flag values (typically either C<0> |
1426 |
or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)): |
1427 |
|
1428 |
C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>, |
1429 |
C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>, |
1430 |
C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>, |
1431 |
C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>, |
1432 |
C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or |
1433 |
C<IO::AIO::FIEMAP_EXTENT_SHARED>. |
1434 |
|
1435 |
At the time of this writing (Linux 3.2), this request is unreliable unless |
1436 |
C<$count> is C<undef>, as the kernel has all sorts of bugs preventing |
1437 |
it to return all extents of a range for files with a large number of |
1438 |
extents. The code (only) works around all these issues if C<$count> is |
1439 |
C<undef>. |
1440 |
|
1441 |
=item aio_group $callback->(...) |
1442 |
|
1443 |
This is a very special aio request: Instead of doing something, it is a |
1444 |
container for other aio requests, which is useful if you want to bundle |
1445 |
many requests into a single, composite, request with a definite callback |
1446 |
and the ability to cancel the whole request with its subrequests. |
1447 |
|
1448 |
Returns an object of class L<IO::AIO::GRP>. See its documentation below |
1449 |
for more info. |
1450 |
|
1451 |
Example: |
1452 |
|
1453 |
my $grp = aio_group sub { |
1454 |
print "all stats done\n"; |
1455 |
}; |
1456 |
|
1457 |
add $grp |
1458 |
(aio_stat ...), |
1459 |
(aio_stat ...), |
1460 |
...; |
1461 |
|
1462 |
=item aio_nop $callback->() |
1463 |
|
1464 |
This is a special request - it does nothing in itself and is only used for |
1465 |
side effects, such as when you want to add a dummy request to a group so |
1466 |
that finishing the requests in the group depends on executing the given |
1467 |
code. |
1468 |
|
1469 |
While this request does nothing, it still goes through the execution |
1470 |
phase and still requires a worker thread. Thus, the callback will not |
1471 |
be executed immediately but only after other requests in the queue have |
1472 |
entered their execution phase. This can be used to measure request |
1473 |
latency. |
1474 |
|
1475 |
=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
1476 |
|
1477 |
Mainly used for debugging and benchmarking, this aio request puts one of |
1478 |
the request workers to sleep for the given time. |
1479 |
|
1480 |
While it is theoretically handy to have simple I/O scheduling requests |
1481 |
like sleep and file handle readable/writable, the overhead this creates is |
1482 |
immense (it blocks a thread for a long time) so do not use this function |
1483 |
except to put your application under artificial I/O pressure. |
1484 |
|
1485 |
=back |
1486 |
|
1487 |
|
1488 |
=head2 IO::AIO::WD - multiple working directories |
1489 |
|
1490 |
Your process only has one current working directory, which is used by all |
1491 |
threads. This makes it hard to use relative paths (some other component |
1492 |
could call C<chdir> at any time, and it is hard to control when the path |
1493 |
will be used by IO::AIO). |
1494 |
|
1495 |
One solution for this is to always use absolute paths. This usually works, |
1496 |
but can be quite slow (the kernel has to walk the whole path on every |
1497 |
access), and can also be a hassle to implement. |
1498 |
|
1499 |
Newer POSIX systems have a number of functions (openat, fdopendir, |
1500 |
futimensat and so on) that make it possible to specify working directories |
1501 |
per operation. |
1502 |
|
1503 |
For portability, and because the clowns who "designed", or shall I write, |
1504 |
perpetrated this new interface were obviously half-drunk, this abstraction |
1505 |
cannot be perfect, though. |
1506 |
|
1507 |
IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD |
1508 |
object. This object stores the canonicalised, absolute version of the |
1509 |
path, and on systems that allow it, also a directory file descriptor. |
1510 |
|
1511 |
Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat> |
1512 |
or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD |
1513 |
object and a pathname instead (or the IO::AIO::WD object alone, which |
1514 |
gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the |
1515 |
IO::AIO::WD object is ignored, otherwise the pathname is resolved relative |
1516 |
to that IO::AIO::WD object. |
1517 |
|
1518 |
For example, to get a wd object for F</etc> and then stat F<passwd> |
1519 |
inside, you would write: |
1520 |
|
1521 |
aio_wd "/etc", sub { |
1522 |
my $etcdir = shift; |
1523 |
|
1524 |
# although $etcdir can be undef on error, there is generally no reason |
1525 |
# to check for errors here, as aio_stat will fail with ENOENT |
1526 |
# when $etcdir is undef. |
1527 |
|
1528 |
aio_stat [$etcdir, "passwd"], sub { |
1529 |
# yay |
1530 |
}; |
1531 |
}; |
1532 |
|
1533 |
The fact that C<aio_wd> is a request and not a normal function shows that |
1534 |
creating an IO::AIO::WD object is itself a potentially blocking operation, |
1535 |
which is why it is done asynchronously. |
1536 |
|
1537 |
To stat the directory obtained with C<aio_wd> above, one could write |
1538 |
either of the following three request calls: |
1539 |
|
1540 |
aio_lstat "/etc" , sub { ... # pathname as normal string |
1541 |
aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself) |
1542 |
aio_lstat $wd , sub { ... # shorthand for the previous |
1543 |
|
1544 |
As with normal pathnames, IO::AIO keeps a copy of the working directory |
1545 |
object and the pathname string, so you could write the following without |
1546 |
causing any issues due to C<$path> getting reused: |
1547 |
|
1548 |
my $path = [$wd, undef]; |
1549 |
|
1550 |
for my $name (qw(abc def ghi)) { |
1551 |
$path->[1] = $name; |
1552 |
aio_stat $path, sub { |
1553 |
# ... |
1554 |
}; |
1555 |
} |
1556 |
|
1557 |
There are some caveats: when directories get renamed (or deleted), the |
1558 |
pathname string doesn't change, so will point to the new directory (or |
1559 |
nowhere at all), while the directory fd, if available on the system, |
1560 |
will still point to the original directory. Most functions accepting a |
1561 |
pathname will use the directory fd on newer systems, and the string on |
1562 |
older systems. Some functions (such as C<aio_realpath>) will always rely on |
1563 |
the string form of the pathname. |
1564 |
|
1565 |
So this functionality is mainly useful to get some protection against |
1566 |
C<chdir>, to easily get an absolute path out of a relative path for future |
1567 |
reference, and to speed up doing many operations in the same directory |
1568 |
(e.g. when stat'ing all files in a directory). |
1569 |
|
1570 |
The following functions implement this working directory abstraction: |
1571 |
|
1572 |
=over 4 |
1573 |
|
1574 |
=item aio_wd $pathname, $callback->($wd) |
1575 |
|
1576 |
Asynchonously canonicalise the given pathname and convert it to an |
1577 |
IO::AIO::WD object representing it. If possible and supported on the |
1578 |
system, also open a directory fd to speed up pathname resolution relative |
1579 |
to this working directory. |
1580 |
|
1581 |
If something goes wrong, then C<undef> is passwd to the callback instead |
1582 |
of a working directory object and C<$!> is set appropriately. Since |
1583 |
passing C<undef> as working directory component of a pathname fails the |
1584 |
request with C<ENOENT>, there is often no need for error checking in the |
1585 |
C<aio_wd> callback, as future requests using the value will fail in the |
1586 |
expected way. |
1587 |
|
1588 |
=item IO::AIO::CWD |
1589 |
|
1590 |
This is a compiletime constant (object) that represents the process |
1591 |
current working directory. |
1592 |
|
1593 |
Specifying this object as working directory object for a pathname is as if |
1594 |
the pathname would be specified directly, without a directory object. For |
1595 |
example, these calls are functionally identical: |
1596 |
|
1597 |
aio_stat "somefile", sub { ... }; |
1598 |
aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; |
1599 |
|
1600 |
=back |
1601 |
|
1602 |
To recover the path associated with an IO::AIO::WD object, you can use |
1603 |
C<aio_realpath>: |
1604 |
|
1605 |
aio_realpath $wd, sub { |
1606 |
warn "path is $_[0]\n"; |
1607 |
}; |
1608 |
|
1609 |
Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir> |
1610 |
sometimes, fall back to using an absolue path. |
1611 |
|
1612 |
=head2 IO::AIO::REQ CLASS |
1613 |
|
1614 |
All non-aggregate C<aio_*> functions return an object of this class when |
1615 |
called in non-void context. |
1616 |
|
1617 |
=over 4 |
1618 |
|
1619 |
=item cancel $req |
1620 |
|
1621 |
Cancels the request, if possible. Has the effect of skipping execution |
1622 |
when entering the B<execute> state and skipping calling the callback when |
1623 |
entering the the B<result> state, but will leave the request otherwise |
1624 |
untouched (with the exception of readdir). That means that requests that |
1625 |
currently execute will not be stopped and resources held by the request |
1626 |
will not be freed prematurely. |
1627 |
|
1628 |
=item cb $req $callback->(...) |
1629 |
|
1630 |
Replace (or simply set) the callback registered to the request. |
1631 |
|
1632 |
=back |
1633 |
|
1634 |
=head2 IO::AIO::GRP CLASS |
1635 |
|
1636 |
This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to |
1637 |
objects of this class, too. |
1638 |
|
1639 |
A IO::AIO::GRP object is a special request that can contain multiple other |
1640 |
aio requests. |
1641 |
|
1642 |
You create one by calling the C<aio_group> constructing function with a |
1643 |
callback that will be called when all contained requests have entered the |
1644 |
C<done> state: |
1645 |
|
1646 |
my $grp = aio_group sub { |
1647 |
print "all requests are done\n"; |
1648 |
}; |
1649 |
|
1650 |
You add requests by calling the C<add> method with one or more |
1651 |
C<IO::AIO::REQ> objects: |
1652 |
|
1653 |
$grp->add (aio_unlink "..."); |
1654 |
|
1655 |
add $grp aio_stat "...", sub { |
1656 |
$_[0] or return $grp->result ("error"); |
1657 |
|
1658 |
# add another request dynamically, if first succeeded |
1659 |
add $grp aio_open "...", sub { |
1660 |
$grp->result ("ok"); |
1661 |
}; |
1662 |
}; |
1663 |
|
1664 |
This makes it very easy to create composite requests (see the source of |
1665 |
C<aio_move> for an application) that work and feel like simple requests. |
1666 |
|
1667 |
=over 4 |
1668 |
|
1669 |
=item * The IO::AIO::GRP objects will be cleaned up during calls to |
1670 |
C<IO::AIO::poll_cb>, just like any other request. |
1671 |
|
1672 |
=item * They can be canceled like any other request. Canceling will cancel not |
1673 |
only the request itself, but also all requests it contains. |
1674 |
|
1675 |
=item * They can also can also be added to other IO::AIO::GRP objects. |
1676 |
|
1677 |
=item * You must not add requests to a group from within the group callback (or |
1678 |
any later time). |
1679 |
|
1680 |
=back |
1681 |
|
1682 |
Their lifetime, simplified, looks like this: when they are empty, they |
1683 |
will finish very quickly. If they contain only requests that are in the |
1684 |
C<done> state, they will also finish. Otherwise they will continue to |
1685 |
exist. |
1686 |
|
1687 |
That means after creating a group you have some time to add requests |
1688 |
(precisely before the callback has been invoked, which is only done within |
1689 |
the C<poll_cb>). And in the callbacks of those requests, you can add |
1690 |
further requests to the group. And only when all those requests have |
1691 |
finished will the the group itself finish. |
1692 |
|
1693 |
=over 4 |
1694 |
|
1695 |
=item add $grp ... |
1696 |
|
1697 |
=item $grp->add (...) |
1698 |
|
1699 |
Add one or more requests to the group. Any type of L<IO::AIO::REQ> can |
1700 |
be added, including other groups, as long as you do not create circular |
1701 |
dependencies. |
1702 |
|
1703 |
Returns all its arguments. |
1704 |
|
1705 |
=item $grp->cancel_subs |
1706 |
|
1707 |
Cancel all subrequests and clears any feeder, but not the group request |
1708 |
itself. Useful when you queued a lot of events but got a result early. |
1709 |
|
1710 |
The group request will finish normally (you cannot add requests to the |
1711 |
group). |
1712 |
|
1713 |
=item $grp->result (...) |
1714 |
|
1715 |
Set the result value(s) that will be passed to the group callback when all |
1716 |
subrequests have finished and set the groups errno to the current value |
1717 |
of errno (just like calling C<errno> without an error number). By default, |
1718 |
no argument will be passed and errno is zero. |
1719 |
|
1720 |
=item $grp->errno ([$errno]) |
1721 |
|
1722 |
Sets the group errno value to C<$errno>, or the current value of errno |
1723 |
when the argument is missing. |
1724 |
|
1725 |
Every aio request has an associated errno value that is restored when |
1726 |
the callback is invoked. This method lets you change this value from its |
1727 |
default (0). |
1728 |
|
1729 |
Calling C<result> will also set errno, so make sure you either set C<$!> |
1730 |
before the call to C<result>, or call c<errno> after it. |
1731 |
|
1732 |
=item feed $grp $callback->($grp) |
1733 |
|
1734 |
Sets a feeder/generator on this group: every group can have an attached |
1735 |
generator that generates requests if idle. The idea behind this is that, |
1736 |
although you could just queue as many requests as you want in a group, |
1737 |
this might starve other requests for a potentially long time. For example, |
1738 |
C<aio_scandir> might generate hundreds of thousands of C<aio_stat> |
1739 |
requests, delaying any later requests for a long time. |
1740 |
|
1741 |
To avoid this, and allow incremental generation of requests, you can |
1742 |
instead a group and set a feeder on it that generates those requests. The |
1743 |
feed callback will be called whenever there are few enough (see C<limit>, |
1744 |
below) requests active in the group itself and is expected to queue more |
1745 |
requests. |
1746 |
|
1747 |
The feed callback can queue as many requests as it likes (i.e. C<add> does |
1748 |
not impose any limits). |
1749 |
|
1750 |
If the feed does not queue more requests when called, it will be |
1751 |
automatically removed from the group. |
1752 |
|
1753 |
If the feed limit is C<0> when this method is called, it will be set to |
1754 |
C<2> automatically. |
1755 |
|
1756 |
Example: |
1757 |
|
1758 |
# stat all files in @files, but only ever use four aio requests concurrently: |
1759 |
|
1760 |
my $grp = aio_group sub { print "finished\n" }; |
1761 |
limit $grp 4; |
1762 |
feed $grp sub { |
1763 |
my $file = pop @files |
1764 |
or return; |
1765 |
|
1766 |
add $grp aio_stat $file, sub { ... }; |
1767 |
}; |
1768 |
|
1769 |
=item limit $grp $num |
1770 |
|
1771 |
Sets the feeder limit for the group: The feeder will be called whenever |
1772 |
the group contains less than this many requests. |
1773 |
|
1774 |
Setting the limit to C<0> will pause the feeding process. |
1775 |
|
1776 |
The default value for the limit is C<0>, but note that setting a feeder |
1777 |
automatically bumps it up to C<2>. |
1778 |
|
1779 |
=back |
1780 |
|
1781 |
=head2 SUPPORT FUNCTIONS |
1782 |
|
1783 |
=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
1784 |
|
1785 |
=over 4 |
1786 |
|
1787 |
=item $fileno = IO::AIO::poll_fileno |
1788 |
|
1789 |
Return the I<request result pipe file descriptor>. This filehandle must be |
1790 |
polled for reading by some mechanism outside this module (e.g. EV, Glib, |
1791 |
select and so on, see below or the SYNOPSIS). If the pipe becomes readable |
1792 |
you have to call C<poll_cb> to check the results. |
1793 |
|
1794 |
See C<poll_cb> for an example. |
1795 |
|
1796 |
=item IO::AIO::poll_cb |
1797 |
|
1798 |
Process some requests that have reached the result phase (i.e. they have |
1799 |
been executed but the results are not yet reported). You have to call |
1800 |
this "regularly" to finish outstanding requests. |
1801 |
|
1802 |
Returns C<0> if all events could be processed (or there were no |
1803 |
events to process), or C<-1> if it returned earlier for whatever |
1804 |
reason. Returns immediately when no events are outstanding. The amount |
1805 |
of events processed depends on the settings of C<IO::AIO::max_poll_req>, |
1806 |
C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>. |
1807 |
|
1808 |
If not all requests were processed for whatever reason, the poll file |
1809 |
descriptor will still be ready when C<poll_cb> returns, so normally you |
1810 |
don't have to do anything special to have it called later. |
1811 |
|
1812 |
Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes |
1813 |
ready, it can be beneficial to call this function from loops which submit |
1814 |
a lot of requests, to make sure the results get processed when they become |
1815 |
available and not just when the loop is finished and the event loop takes |
1816 |
over again. This function returns very fast when there are no outstanding |
1817 |
requests. |
1818 |
|
1819 |
Example: Install an Event watcher that automatically calls |
1820 |
IO::AIO::poll_cb with high priority (more examples can be found in the |
1821 |
SYNOPSIS section, at the top of this document): |
1822 |
|
1823 |
Event->io (fd => IO::AIO::poll_fileno, |
1824 |
poll => 'r', async => 1, |
1825 |
cb => \&IO::AIO::poll_cb); |
1826 |
|
1827 |
=item IO::AIO::poll_wait |
1828 |
|
1829 |
Wait until either at least one request is in the result phase or no |
1830 |
requests are outstanding anymore. |
1831 |
|
1832 |
This is useful if you want to synchronously wait for some requests to |
1833 |
become ready, without actually handling them. |
1834 |
|
1835 |
See C<nreqs> for an example. |
1836 |
|
1837 |
=item IO::AIO::poll |
1838 |
|
1839 |
Waits until some requests have been handled. |
1840 |
|
1841 |
Returns the number of requests processed, but is otherwise strictly |
1842 |
equivalent to: |
1843 |
|
1844 |
IO::AIO::poll_wait, IO::AIO::poll_cb |
1845 |
|
1846 |
=item IO::AIO::flush |
1847 |
|
1848 |
Wait till all outstanding AIO requests have been handled. |
1849 |
|
1850 |
Strictly equivalent to: |
1851 |
|
1852 |
IO::AIO::poll_wait, IO::AIO::poll_cb |
1853 |
while IO::AIO::nreqs; |
1854 |
|
1855 |
=item IO::AIO::max_poll_reqs $nreqs |
1856 |
|
1857 |
=item IO::AIO::max_poll_time $seconds |
1858 |
|
1859 |
These set the maximum number of requests (default C<0>, meaning infinity) |
1860 |
that are being processed by C<IO::AIO::poll_cb> in one call, respectively |
1861 |
the maximum amount of time (default C<0>, meaning infinity) spent in |
1862 |
C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount |
1863 |
of time C<poll_cb> is allowed to use). |
1864 |
|
1865 |
Setting C<max_poll_time> to a non-zero value creates an overhead of one |
1866 |
syscall per request processed, which is not normally a problem unless your |
1867 |
callbacks are really really fast or your OS is really really slow (I am |
1868 |
not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead. |
1869 |
|
1870 |
Setting these is useful if you want to ensure some level of |
1871 |
interactiveness when perl is not fast enough to process all requests in |
1872 |
time. |
1873 |
|
1874 |
For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
1875 |
|
1876 |
Example: Install an Event watcher that automatically calls |
1877 |
IO::AIO::poll_cb with low priority, to ensure that other parts of the |
1878 |
program get the CPU sometimes even under high AIO load. |
1879 |
|
1880 |
# try not to spend much more than 0.1s in poll_cb |
1881 |
IO::AIO::max_poll_time 0.1; |
1882 |
|
1883 |
# use a low priority so other tasks have priority |
1884 |
Event->io (fd => IO::AIO::poll_fileno, |
1885 |
poll => 'r', nice => 1, |
1886 |
cb => &IO::AIO::poll_cb); |
1887 |
|
1888 |
=back |
1889 |
|
1890 |
=head3 CONTROLLING THE NUMBER OF THREADS |
1891 |
|
1892 |
=over |
1893 |
|
1894 |
=item IO::AIO::min_parallel $nthreads |
1895 |
|
1896 |
Set the minimum number of AIO threads to C<$nthreads>. The current |
1897 |
default is C<8>, which means eight asynchronous operations can execute |
1898 |
concurrently at any one time (the number of outstanding requests, |
1899 |
however, is unlimited). |
1900 |
|
1901 |
IO::AIO starts threads only on demand, when an AIO request is queued and |
1902 |
no free thread exists. Please note that queueing up a hundred requests can |
1903 |
create demand for a hundred threads, even if it turns out that everything |
1904 |
is in the cache and could have been processed faster by a single thread. |
1905 |
|
1906 |
It is recommended to keep the number of threads relatively low, as some |
1907 |
Linux kernel versions will scale negatively with the number of threads |
1908 |
(higher parallelity => MUCH higher latency). With current Linux 2.6 |
1909 |
versions, 4-32 threads should be fine. |
1910 |
|
1911 |
Under most circumstances you don't need to call this function, as the |
1912 |
module selects a default that is suitable for low to moderate load. |
1913 |
|
1914 |
=item IO::AIO::max_parallel $nthreads |
1915 |
|
1916 |
Sets the maximum number of AIO threads to C<$nthreads>. If more than the |
1917 |
specified number of threads are currently running, this function kills |
1918 |
them. This function blocks until the limit is reached. |
1919 |
|
1920 |
While C<$nthreads> are zero, aio requests get queued but not executed |
1921 |
until the number of threads has been increased again. |
1922 |
|
1923 |
This module automatically runs C<max_parallel 0> at program end, to ensure |
1924 |
that all threads are killed and that there are no outstanding requests. |
1925 |
|
1926 |
Under normal circumstances you don't need to call this function. |
1927 |
|
1928 |
=item IO::AIO::max_idle $nthreads |
1929 |
|
1930 |
Limit the number of threads (default: 4) that are allowed to idle |
1931 |
(i.e., threads that did not get a request to process within the idle |
1932 |
timeout (default: 10 seconds). That means if a thread becomes idle while |
1933 |
C<$nthreads> other threads are also idle, it will free its resources and |
1934 |
exit. |
1935 |
|
1936 |
This is useful when you allow a large number of threads (e.g. 100 or 1000) |
1937 |
to allow for extremely high load situations, but want to free resources |
1938 |
under normal circumstances (1000 threads can easily consume 30MB of RAM). |
1939 |
|
1940 |
The default is probably ok in most situations, especially if thread |
1941 |
creation is fast. If thread creation is very slow on your system you might |
1942 |
want to use larger values. |
1943 |
|
1944 |
=item IO::AIO::idle_timeout $seconds |
1945 |
|
1946 |
Sets the minimum idle timeout (default 10) after which worker threads are |
1947 |
allowed to exit. SEe C<IO::AIO::max_idle>. |
1948 |
|
1949 |
=item IO::AIO::max_outstanding $maxreqs |
1950 |
|
1951 |
Sets the maximum number of outstanding requests to C<$nreqs>. If |
1952 |
you do queue up more than this number of requests, the next call to |
1953 |
C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as |
1954 |
C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no |
1955 |
longer exceeded. |
1956 |
|
1957 |
In other words, this setting does not enforce a queue limit, but can be |
1958 |
used to make poll functions block if the limit is exceeded. |
1959 |
|
1960 |
This is a very bad function to use in interactive programs because it |
1961 |
blocks, and a bad way to reduce concurrency because it is inexact: Better |
1962 |
use an C<aio_group> together with a feed callback. |
1963 |
|
1964 |
Its main use is in scripts without an event loop - when you want to stat |
1965 |
a lot of files, you can write something like this: |
1966 |
|
1967 |
IO::AIO::max_outstanding 32; |
1968 |
|
1969 |
for my $path (...) { |
1970 |
aio_stat $path , ...; |
1971 |
IO::AIO::poll_cb; |
1972 |
} |
1973 |
|
1974 |
IO::AIO::flush; |
1975 |
|
1976 |
The call to C<poll_cb> inside the loop will normally return instantly, but |
1977 |
as soon as more thna C<32> reqeusts are in-flight, it will block until |
1978 |
some requests have been handled. This keeps the loop from pushing a large |
1979 |
number of C<aio_stat> requests onto the queue. |
1980 |
|
1981 |
The default value for C<max_outstanding> is very large, so there is no |
1982 |
practical limit on the number of outstanding requests. |
1983 |
|
1984 |
=back |
1985 |
|
1986 |
=head3 STATISTICAL INFORMATION |
1987 |
|
1988 |
=over |
1989 |
|
1990 |
=item IO::AIO::nreqs |
1991 |
|
1992 |
Returns the number of requests currently in the ready, execute or pending |
1993 |
states (i.e. for which their callback has not been invoked yet). |
1994 |
|
1995 |
Example: wait till there are no outstanding requests anymore: |
1996 |
|
1997 |
IO::AIO::poll_wait, IO::AIO::poll_cb |
1998 |
while IO::AIO::nreqs; |
1999 |
|
2000 |
=item IO::AIO::nready |
2001 |
|
2002 |
Returns the number of requests currently in the ready state (not yet |
2003 |
executed). |
2004 |
|
2005 |
=item IO::AIO::npending |
2006 |
|
2007 |
Returns the number of requests currently in the pending state (executed, |
2008 |
but not yet processed by poll_cb). |
2009 |
|
2010 |
=back |
2011 |
|
2012 |
=head3 MISCELLANEOUS FUNCTIONS |
2013 |
|
2014 |
IO::AIO implements some functions that are useful when you want to use |
2015 |
some "Advanced I/O" function not available to in Perl, without going the |
2016 |
"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*> |
2017 |
counterpart. |
2018 |
|
2019 |
=over 4 |
2020 |
|
2021 |
=item $numfd = IO::AIO::get_fdlimit |
2022 |
|
2023 |
This function is I<EXPERIMENTAL> and subject to change. |
2024 |
|
2025 |
Tries to find the current file descriptor limit and returns it, or |
2026 |
C<undef> and sets C<$!> in case of an error. The limit is one larger than |
2027 |
the highest valid file descriptor number. |
2028 |
|
2029 |
=item IO::AIO::min_fdlimit [$numfd] |
2030 |
|
2031 |
This function is I<EXPERIMENTAL> and subject to change. |
2032 |
|
2033 |
Try to increase the current file descriptor limit(s) to at least C<$numfd> |
2034 |
by changing the soft or hard file descriptor resource limit. If C<$numfd> |
2035 |
is missing, it will try to set a very high limit, although this is not |
2036 |
recommended when you know the actual minimum that you require. |
2037 |
|
2038 |
If the limit cannot be raised enough, the function makes a best-effort |
2039 |
attempt to increase the limit as much as possible, using various |
2040 |
tricks, while still failing. You can query the resulting limit using |
2041 |
C<IO::AIO::get_fdlimit>. |
2042 |
|
2043 |
If an error occurs, returns C<undef> and sets C<$!>, otherwise returns |
2044 |
true. |
2045 |
|
2046 |
=item IO::AIO::sendfile $ofh, $ifh, $offset, $count |
2047 |
|
2048 |
Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>, |
2049 |
but is blocking (this makes most sense if you know the input data is |
2050 |
likely cached already and the output filehandle is set to non-blocking |
2051 |
operations). |
2052 |
|
2053 |
Returns the number of bytes copied, or C<-1> on error. |
2054 |
|
2055 |
=item IO::AIO::fadvise $fh, $offset, $len, $advice |
2056 |
|
2057 |
Simply calls the C<posix_fadvise> function (see its |
2058 |
manpage for details). The following advice constants are |
2059 |
available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>, |
2060 |
C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>, |
2061 |
C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>. |
2062 |
|
2063 |
On systems that do not implement C<posix_fadvise>, this function returns |
2064 |
ENOSYS, otherwise the return value of C<posix_fadvise>. |
2065 |
|
2066 |
=item IO::AIO::madvise $scalar, $offset, $len, $advice |
2067 |
|
2068 |
Simply calls the C<posix_madvise> function (see its |
2069 |
manpage for details). The following advice constants are |
2070 |
available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, |
2071 |
C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, |
2072 |
C<IO::AIO::MADV_DONTNEED>. |
2073 |
|
2074 |
If C<$offset> is negative, counts from the end. If C<$length> is negative, |
2075 |
the remaining length of the C<$scalar> is used. If possible, C<$length> |
2076 |
will be reduced to fit into the C<$scalar>. |
2077 |
|
2078 |
On systems that do not implement C<posix_madvise>, this function returns |
2079 |
ENOSYS, otherwise the return value of C<posix_madvise>. |
2080 |
|
2081 |
=item IO::AIO::mprotect $scalar, $offset, $len, $protect |
2082 |
|
2083 |
Simply calls the C<mprotect> function on the preferably AIO::mmap'ed |
2084 |
$scalar (see its manpage for details). The following protect |
2085 |
constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, |
2086 |
C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. |
2087 |
|
2088 |
If C<$offset> is negative, counts from the end. If C<$length> is negative, |
2089 |
the remaining length of the C<$scalar> is used. If possible, C<$length> |
2090 |
will be reduced to fit into the C<$scalar>. |
2091 |
|
2092 |
On systems that do not implement C<mprotect>, this function returns |
2093 |
ENOSYS, otherwise the return value of C<mprotect>. |
2094 |
|
2095 |
=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] |
2096 |
|
2097 |
Memory-maps a file (or anonymous memory range) and attaches it to the |
2098 |
given C<$scalar>, which will act like a string scalar. Returns true on |
2099 |
success, and false otherwise. |
2100 |
|
2101 |
The scalar must exist, but its contents do not matter - this means you |
2102 |
cannot use a nonexistant array or hash element. When in doubt, C<undef> |
2103 |
the scalar first. |
2104 |
|
2105 |
The only operations allowed on the mmapped scalar are C<substr>/C<vec>, |
2106 |
which don't change the string length, and most read-only operations such |
2107 |
as copying it or searching it with regexes and so on. |
2108 |
|
2109 |
Anything else is unsafe and will, at best, result in memory leaks. |
2110 |
|
2111 |
The memory map associated with the C<$scalar> is automatically removed |
2112 |
when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap> |
2113 |
or C<IO::AIO::munmap> functions are called on it. |
2114 |
|
2115 |
This calls the C<mmap>(2) function internally. See your system's manual |
2116 |
page for details on the C<$length>, C<$prot> and C<$flags> parameters. |
2117 |
|
2118 |
The C<$length> must be larger than zero and smaller than the actual |
2119 |
filesize. |
2120 |
|
2121 |
C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, |
2122 |
C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, |
2123 |
|
2124 |
C<$flags> can be a combination of |
2125 |
C<IO::AIO::MAP_SHARED> or |
2126 |
C<IO::AIO::MAP_PRIVATE>, |
2127 |
or a number of system-specific flags (when not available, the are C<0>): |
2128 |
C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant), |
2129 |
C<IO::AIO::MAP_LOCKED>, |
2130 |
C<IO::AIO::MAP_NORESERVE>, |
2131 |
C<IO::AIO::MAP_POPULATE>, |
2132 |
C<IO::AIO::MAP_NONBLOCK>, |
2133 |
C<IO::AIO::MAP_FIXED>, |
2134 |
C<IO::AIO::MAP_GROWSDOWN>, |
2135 |
C<IO::AIO::MAP_32BIT>, |
2136 |
C<IO::AIO::MAP_HUGETLB> or |
2137 |
C<IO::AIO::MAP_STACK>. |
2138 |
|
2139 |
If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. |
2140 |
|
2141 |
C<$offset> is the offset from the start of the file - it generally must be |
2142 |
a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. |
2143 |
|
2144 |
Example: |
2145 |
|
2146 |
use Digest::MD5; |
2147 |
use IO::AIO; |
2148 |
|
2149 |
open my $fh, "<verybigfile" |
2150 |
or die "$!"; |
2151 |
|
2152 |
IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh |
2153 |
or die "verybigfile: $!"; |
2154 |
|
2155 |
my $fast_md5 = md5 $data; |
2156 |
|
2157 |
=item IO::AIO::munmap $scalar |
2158 |
|
2159 |
Removes a previous mmap and undefines the C<$scalar>. |
2160 |
|
2161 |
=item IO::AIO::munlock $scalar, $offset = 0, $length = undef |
2162 |
|
2163 |
Calls the C<munlock> function, undoing the effects of a previous |
2164 |
C<aio_mlock> call (see its description for details). |
2165 |
|
2166 |
=item IO::AIO::munlockall |
2167 |
|
2168 |
Calls the C<munlockall> function. |
2169 |
|
2170 |
On systems that do not implement C<munlockall>, this function returns |
2171 |
ENOSYS, otherwise the return value of C<munlockall>. |
2172 |
|
2173 |
=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags |
2174 |
|
2175 |
Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or |
2176 |
C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they |
2177 |
should be the file offset. |
2178 |
|
2179 |
C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might |
2180 |
silently corrupt the data in this case. |
2181 |
|
2182 |
The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>, |
2183 |
C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and |
2184 |
C<IO::AIO::SPLICE_F_GIFT>. |
2185 |
|
2186 |
See the C<splice(2)> manpage for details. |
2187 |
|
2188 |
=item IO::AIO::tee $r_fh, $w_fh, $length, $flags |
2189 |
|
2190 |
Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the |
2191 |
description for C<IO::AIO::splice> above for details. |
2192 |
|
2193 |
=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size] |
2194 |
|
2195 |
Attempts to query or change the pipe buffer size. Obviously works only |
2196 |
on pipes, and currently works only on GNU/Linux systems, and fails with |
2197 |
C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer |
2198 |
size on other systems, drop me a note. |
2199 |
|
2200 |
=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags] |
2201 |
|
2202 |
This is a direct interface to the Linux L<pipe2(2)> system call. If |
2203 |
C<$flags> is missing or C<0>, then this should be the same as a call to |
2204 |
perl's built-in C<pipe> function and create a new pipe, and works on |
2205 |
systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe |
2206 |
(..., 4096, O_BINARY)>. |
2207 |
|
2208 |
If C<$flags> is non-zero, it tries to invoke the pipe2 system call with |
2209 |
the given flags (Linux 2.6.27, glibc 2.9). |
2210 |
|
2211 |
On success, the read and write file handles are returned. |
2212 |
|
2213 |
On error, nothing will be returned. If the pipe2 syscall is missing and |
2214 |
C<$flags> is non-zero, fails with C<ENOSYS>. |
2215 |
|
2216 |
Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the |
2217 |
time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and |
2218 |
C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported. |
2219 |
|
2220 |
Example: create a pipe race-free w.r.t. threads and fork: |
2221 |
|
2222 |
my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC |
2223 |
or die "pipe2: $!\n"; |
2224 |
|
2225 |
=item $fh = IO::AIO::eventfd [$initval, [$flags]] |
2226 |
|
2227 |
This is a direct interface to the Linux L<eventfd(2)> system call. The |
2228 |
(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both. |
2229 |
|
2230 |
On success, the new eventfd filehandle is returned, otherwise returns |
2231 |
C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>. |
2232 |
|
2233 |
Please refer to L<eventfd(2)> for more info on this call. |
2234 |
|
2235 |
The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>, |
2236 |
C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30). |
2237 |
|
2238 |
Example: create a new eventfd filehandle: |
2239 |
|
2240 |
$fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC |
2241 |
or die "eventfd: $!\n"; |
2242 |
|
2243 |
=item $fh = IO::AIO::timerfd_create $clockid[, $flags] |
2244 |
|
2245 |
This is a direct interface to the Linux L<timerfd_create(2)> system call. The |
2246 |
(unhelpful) default for C<$flags> is C<0>. |
2247 |
|
2248 |
On success, the new timerfd filehandle is returned, otherwise returns |
2249 |
C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>. |
2250 |
|
2251 |
Please refer to L<timerfd_create(2)> for more info on this call. |
2252 |
|
2253 |
The following C<$clockid> values are |
2254 |
available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC> |
2255 |
C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15) |
2256 |
C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and |
2257 |
C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11). |
2258 |
|
2259 |
The following C<$flags> values are available (Linux |
2260 |
2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>. |
2261 |
|
2262 |
Example: create a new timerfd and set it to one-second repeated alarms, |
2263 |
then wait for two alarms: |
2264 |
|
2265 |
my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC |
2266 |
or die "timerfd_create: $!\n"; |
2267 |
|
2268 |
defined IO::AIO::timerfd_settime $fh, 0, 1, 1 |
2269 |
or die "timerfd_settime: $!\n"; |
2270 |
|
2271 |
for (1..2) { |
2272 |
8 == sysread $fh, my $buf, 8 |
2273 |
or die "timerfd read failure\n"; |
2274 |
|
2275 |
printf "number of expirations (likely 1): %d\n", |
2276 |
unpack "Q", $buf; |
2277 |
} |
2278 |
|
2279 |
=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value |
2280 |
|
2281 |
This is a direct interface to the Linux L<timerfd_settime(2)> system |
2282 |
call. Please refer to its manpage for more info on this call. |
2283 |
|
2284 |
The new itimerspec is specified using two (possibly fractional) second |
2285 |
values, C<$new_interval> and C<$new_value>). |
2286 |
|
2287 |
On success, the current interval and value are returned (as per |
2288 |
C<timerfd_gettime>). On failure, the empty list is returned. |
2289 |
|
2290 |
The following C<$flags> values are |
2291 |
available: C<IO::AIO::TFD_TIMER_ABSTIME> and |
2292 |
C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>. |
2293 |
|
2294 |
See C<IO::AIO::timerfd_create> for a full example. |
2295 |
|
2296 |
=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh |
2297 |
|
2298 |
This is a direct interface to the Linux L<timerfd_gettime(2)> system |
2299 |
call. Please refer to its manpage for more info on this call. |
2300 |
|
2301 |
On success, returns the current values of interval and value for the given |
2302 |
timerfd (as potentially fractional second values). On failure, the empty |
2303 |
list is returned. |
2304 |
|
2305 |
=back |
2306 |
|
2307 |
=cut |
2308 |
|
2309 |
min_parallel 8; |
2310 |
|
2311 |
END { flush } |
2312 |
|
2313 |
1; |
2314 |
|
2315 |
=head1 EVENT LOOP INTEGRATION |
2316 |
|
2317 |
It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO |
2318 |
automatically into many event loops: |
2319 |
|
2320 |
# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
2321 |
use AnyEvent::AIO; |
2322 |
|
2323 |
You can also integrate IO::AIO manually into many event loops, here are |
2324 |
some examples of how to do this: |
2325 |
|
2326 |
# EV integration |
2327 |
my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
2328 |
|
2329 |
# Event integration |
2330 |
Event->io (fd => IO::AIO::poll_fileno, |
2331 |
poll => 'r', |
2332 |
cb => \&IO::AIO::poll_cb); |
2333 |
|
2334 |
# Glib/Gtk2 integration |
2335 |
add_watch Glib::IO IO::AIO::poll_fileno, |
2336 |
in => sub { IO::AIO::poll_cb; 1 }; |
2337 |
|
2338 |
# Tk integration |
2339 |
Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
2340 |
readable => \&IO::AIO::poll_cb); |
2341 |
|
2342 |
# Danga::Socket integration |
2343 |
Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
2344 |
\&IO::AIO::poll_cb); |
2345 |
|
2346 |
=head2 FORK BEHAVIOUR |
2347 |
|
2348 |
Usage of pthreads in a program changes the semantics of fork |
2349 |
considerably. Specifically, only async-safe functions can be called after |
2350 |
fork. Perl doesn't know about this, so in general, you cannot call fork |
2351 |
with defined behaviour in perl if pthreads are involved. IO::AIO uses |
2352 |
pthreads, so this applies, but many other extensions and (for inexplicable |
2353 |
reasons) perl itself often is linked against pthreads, so this limitation |
2354 |
applies to quite a lot of perls. |
2355 |
|
2356 |
This module no longer tries to fight your OS, or POSIX. That means IO::AIO |
2357 |
only works in the process that loaded it. Forking is fully supported, but |
2358 |
using IO::AIO in the child is not. |
2359 |
|
2360 |
You might get around by not I<using> IO::AIO before (or after) |
2361 |
forking. You could also try to call the L<IO::AIO::reinit> function in the |
2362 |
child: |
2363 |
|
2364 |
=over 4 |
2365 |
|
2366 |
=item IO::AIO::reinit |
2367 |
|
2368 |
Abandons all current requests and I/O threads and simply reinitialises all |
2369 |
data structures. This is not an operation supported by any standards, but |
2370 |
happens to work on GNU/Linux and some newer BSD systems. |
2371 |
|
2372 |
The only reasonable use for this function is to call it after forking, if |
2373 |
C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in |
2374 |
the process will result in undefined behaviour. Calling it at any time |
2375 |
will also result in any undefined (by POSIX) behaviour. |
2376 |
|
2377 |
=back |
2378 |
|
2379 |
=head2 LINUX-SPECIFIC CALLS |
2380 |
|
2381 |
When a call is documented as "linux-specific" then this means it |
2382 |
originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the |
2383 |
availability and compatibility of such calls regardless of the platform |
2384 |
it is compiled on, so platforms such as FreeBSD which often implement |
2385 |
these calls will work. When in doubt, call them and see if they fail wth |
2386 |
C<ENOSYS>. |
2387 |
|
2388 |
=head2 MEMORY USAGE |
2389 |
|
2390 |
Per-request usage: |
2391 |
|
2392 |
Each aio request uses - depending on your architecture - around 100-200 |
2393 |
bytes of memory. In addition, stat requests need a stat buffer (possibly |
2394 |
a few hundred bytes), readdir requires a result buffer and so on. Perl |
2395 |
scalars and other data passed into aio requests will also be locked and |
2396 |
will consume memory till the request has entered the done state. |
2397 |
|
2398 |
This is not awfully much, so queuing lots of requests is not usually a |
2399 |
problem. |
2400 |
|
2401 |
Per-thread usage: |
2402 |
|
2403 |
In the execution phase, some aio requests require more memory for |
2404 |
temporary buffers, and each thread requires a stack and other data |
2405 |
structures (usually around 16k-128k, depending on the OS). |
2406 |
|
2407 |
=head1 KNOWN BUGS |
2408 |
|
2409 |
Known bugs will be fixed in the next release :) |
2410 |
|
2411 |
=head1 KNOWN ISSUES |
2412 |
|
2413 |
Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap> |
2414 |
or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as |
2415 |
non-created hash slots or other scalars I didn't think of. It's best to |
2416 |
avoid such and either use scalar variables or making sure that the scalar |
2417 |
exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied). |
2418 |
|
2419 |
I am not sure anything can be done about this, so this is considered a |
2420 |
known issue, rather than a bug. |
2421 |
|
2422 |
=head1 SEE ALSO |
2423 |
|
2424 |
L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a |
2425 |
more natural syntax. |
2426 |
|
2427 |
=head1 AUTHOR |
2428 |
|
2429 |
Marc Lehmann <schmorp@schmorp.de> |
2430 |
http://home.schmorp.de/ |
2431 |
|
2432 |
=cut |
2433 |
|