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Revision 1.155 by root, Sun Jun 14 20:36:59 2009 UTC vs.
Revision 1.222 by root, Fri Apr 6 11:39:25 2012 UTC

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4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
9 aio_open "/etc/passwd", O_RDONLY, 0, sub { 9 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10 my $fh = shift 10 my $fh = shift
11 or die "/etc/passwd: $!"; 11 or die "/etc/passwd: $!";
12 ... 12 ...
13 }; 13 };
14 14
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26 $req->cancel; # cancel request if still in queue 26 $req->cancel; # cancel request if still in queue
27 27
28 my $grp = aio_group sub { print "all stats done\n" }; 28 my $grp = aio_group sub { print "all stats done\n" };
29 add $grp aio_stat "..." for ...; 29 add $grp aio_stat "..." for ...;
30 30
31 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32 use AnyEvent::AIO;
33
34 # EV integration
35 my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37 # Event integration
38 Event->io (fd => IO::AIO::poll_fileno,
39 poll => 'r',
40 cb => \&IO::AIO::poll_cb);
41
42 # Glib/Gtk2 integration
43 add_watch Glib::IO IO::AIO::poll_fileno,
44 in => sub { IO::AIO::poll_cb; 1 };
45
46 # Tk integration
47 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48 readable => \&IO::AIO::poll_cb);
49
50 # Danga::Socket integration
51 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52 \&IO::AIO::poll_cb);
53
54=head1 DESCRIPTION 31=head1 DESCRIPTION
55 32
56This module implements asynchronous I/O using whatever means your 33This module implements asynchronous I/O using whatever means your
57operating system supports. 34operating system supports. It is implemented as an interface to C<libeio>
35(L<http://software.schmorp.de/pkg/libeio.html>).
58 36
59Asynchronous means that operations that can normally block your program 37Asynchronous means that operations that can normally block your program
60(e.g. reading from disk) will be done asynchronously: the operation 38(e.g. reading from disk) will be done asynchronously: the operation
61will still block, but you can do something else in the meantime. This 39will still block, but you can do something else in the meantime. This
62is extremely useful for programs that need to stay interactive even 40is extremely useful for programs that need to stay interactive even
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66on a RAID volume or over NFS when you do a number of stat operations 44on a RAID volume or over NFS when you do a number of stat operations
67concurrently. 45concurrently.
68 46
69While most of this works on all types of file descriptors (for 47While most of this works on all types of file descriptors (for
70example sockets), using these functions on file descriptors that 48example sockets), using these functions on file descriptors that
71support nonblocking operation (again, sockets, pipes etc.) is very 49support nonblocking operation (again, sockets, pipes etc.) is
72inefficient. Use an event loop for that (such as the L<Event|Event> 50very inefficient. Use an event loop for that (such as the L<EV>
73module): IO::AIO will naturally fit into such an event loop itself. 51module): IO::AIO will naturally fit into such an event loop itself.
74 52
75In this version, a number of threads are started that execute your 53In this version, a number of threads are started that execute your
76requests and signal their completion. You don't need thread support 54requests and signal their completion. You don't need thread support
77in perl, and the threads created by this module will not be visible 55in perl, and the threads created by this module will not be visible
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87yourself, always call C<poll_cb> from within the same thread, or never 65yourself, always call C<poll_cb> from within the same thread, or never
88call C<poll_cb> (or other C<aio_> functions) recursively. 66call C<poll_cb> (or other C<aio_> functions) recursively.
89 67
90=head2 EXAMPLE 68=head2 EXAMPLE
91 69
92This is a simple example that uses the Event module and loads 70This is a simple example that uses the EV module and loads
93F</etc/passwd> asynchronously: 71F</etc/passwd> asynchronously:
94 72
95 use Fcntl; 73 use Fcntl;
96 use Event; 74 use EV;
97 use IO::AIO; 75 use IO::AIO;
98 76
99 # register the IO::AIO callback with Event 77 # register the IO::AIO callback with EV
100 Event->io (fd => IO::AIO::poll_fileno, 78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
101 poll => 'r',
102 cb => \&IO::AIO::poll_cb);
103 79
104 # queue the request to open /etc/passwd 80 # queue the request to open /etc/passwd
105 aio_open "/etc/passwd", O_RDONLY, 0, sub { 81 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106 my $fh = shift 82 my $fh = shift
107 or die "error while opening: $!"; 83 or die "error while opening: $!";
108 84
109 # stat'ing filehandles is generally non-blocking 85 # stat'ing filehandles is generally non-blocking
110 my $size = -s $fh; 86 my $size = -s $fh;
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119 95
120 # file contents now in $contents 96 # file contents now in $contents
121 print $contents; 97 print $contents;
122 98
123 # exit event loop and program 99 # exit event loop and program
124 Event::unloop; 100 EV::unloop;
125 }; 101 };
126 }; 102 };
127 103
128 # possibly queue up other requests, or open GUI windows, 104 # possibly queue up other requests, or open GUI windows,
129 # check for sockets etc. etc. 105 # check for sockets etc. etc.
130 106
131 # process events as long as there are some: 107 # process events as long as there are some:
132 Event::loop; 108 EV::loop;
133 109
134=head1 REQUEST ANATOMY AND LIFETIME 110=head1 REQUEST ANATOMY AND LIFETIME
135 111
136Every C<aio_*> function creates a request. which is a C data structure not 112Every C<aio_*> function creates a request. which is a C data structure not
137directly visible to Perl. 113directly visible to Perl.
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187 163
188package IO::AIO; 164package IO::AIO;
189 165
190use Carp (); 166use Carp ();
191 167
192no warnings; 168use common::sense;
193use strict 'vars';
194 169
195use base 'Exporter'; 170use base 'Exporter';
196 171
197BEGIN { 172BEGIN {
198 our $VERSION = '3.23'; 173 our $VERSION = '4.13';
199 174
200 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 175 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
201 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx 176 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync 177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
203 aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead 178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
179 aio_pathsync aio_readahead aio_fiemap
204 aio_rename aio_link aio_move aio_copy aio_group 180 aio_rename aio_link aio_move aio_copy aio_group
205 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 181 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206 aio_chmod aio_utime aio_truncate); 182 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs
185 aio_wd);
207 186
208 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210 min_parallel max_parallel max_idle 189 min_parallel max_parallel max_idle idle_timeout
211 nreqs nready npending nthreads 190 nreqs nready npending nthreads
212 max_poll_time max_poll_reqs); 191 max_poll_time max_poll_reqs
192 sendfile fadvise madvise
193 mmap munmap munlock munlockall);
213 194
214 push @AIO_REQ, qw(aio_busy); # not exported 195 push @AIO_REQ, qw(aio_busy); # not exported
215 196
216 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 197 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217 198
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219 XSLoader::load ("IO::AIO", $VERSION); 200 XSLoader::load ("IO::AIO", $VERSION);
220} 201}
221 202
222=head1 FUNCTIONS 203=head1 FUNCTIONS
223 204
224=head2 AIO REQUEST FUNCTIONS 205=head2 QUICK OVERVIEW
206
207This section simply lists the prototypes of the most important functions
208for quick reference. See the following sections for function-by-function
209documentation.
210
211 aio_wd $pathname, $callback->($wd)
212 aio_open $pathname, $flags, $mode, $callback->($fh)
213 aio_close $fh, $callback->($status)
214 aio_seek $fh,$offset,$whence, $callback->($offs)
215 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
217 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
218 aio_readahead $fh,$offset,$length, $callback->($retval)
219 aio_stat $fh_or_path, $callback->($status)
220 aio_lstat $fh, $callback->($status)
221 aio_statvfs $fh_or_path, $callback->($statvfs)
222 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
223 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status)
225 aio_truncate $fh_or_path, $offset, $callback->($status)
226 aio_unlink $pathname, $callback->($status)
227 aio_mknod $pathname, $mode, $dev, $callback->($status)
228 aio_link $srcpath, $dstpath, $callback->($status)
229 aio_symlink $srcpath, $dstpath, $callback->($status)
230 aio_readlink $pathname, $callback->($link)
231 aio_realpath $pathname, $callback->($link)
232 aio_rename $srcpath, $dstpath, $callback->($status)
233 aio_mkdir $pathname, $mode, $callback->($status)
234 aio_rmdir $pathname, $callback->($status)
235 aio_readdir $pathname, $callback->($entries)
236 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
237 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
238 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
239 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
240 aio_load $pathname, $data, $callback->($status)
241 aio_copy $srcpath, $dstpath, $callback->($status)
242 aio_move $srcpath, $dstpath, $callback->($status)
243 aio_rmtree $pathname, $callback->($status)
244 aio_sync $callback->($status)
245 aio_syncfs $fh, $callback->($status)
246 aio_fsync $fh, $callback->($status)
247 aio_fdatasync $fh, $callback->($status)
248 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
249 aio_pathsync $pathname, $callback->($status)
250 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
252 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
253 aio_mlockall $flags, $callback->($status)
254 aio_group $callback->(...)
255 aio_nop $callback->()
256
257 $prev_pri = aioreq_pri [$pri]
258 aioreq_nice $pri_adjust
259
260 IO::AIO::poll_wait
261 IO::AIO::poll_cb
262 IO::AIO::poll
263 IO::AIO::flush
264 IO::AIO::max_poll_reqs $nreqs
265 IO::AIO::max_poll_time $seconds
266 IO::AIO::min_parallel $nthreads
267 IO::AIO::max_parallel $nthreads
268 IO::AIO::max_idle $nthreads
269 IO::AIO::idle_timeout $seconds
270 IO::AIO::max_outstanding $maxreqs
271 IO::AIO::nreqs
272 IO::AIO::nready
273 IO::AIO::npending
274
275 IO::AIO::sendfile $ofh, $ifh, $offset, $count
276 IO::AIO::fadvise $fh, $offset, $len, $advice
277 IO::AIO::madvise $scalar, $offset, $length, $advice
278 IO::AIO::mprotect $scalar, $offset, $length, $protect
279 IO::AIO::munlock $scalar, $offset = 0, $length = undef
280 IO::AIO::munlockall
281
282=head2 API NOTES
225 283
226All the C<aio_*> calls are more or less thin wrappers around the syscall 284All the C<aio_*> calls are more or less thin wrappers around the syscall
227with the same name (sans C<aio_>). The arguments are similar or identical, 285with the same name (sans C<aio_>). The arguments are similar or identical,
228and they all accept an additional (and optional) C<$callback> argument 286and they all accept an additional (and optional) C<$callback> argument
229which must be a code reference. This code reference will get called with 287which must be a code reference. This code reference will be called after
230the syscall return code (e.g. most syscalls return C<-1> on error, unlike 288the syscall has been executed in an asynchronous fashion. The results
231perl, which usually delivers "false") as its sole argument after the given 289of the request will be passed as arguments to the callback (and, if an
232syscall has been executed asynchronously. 290error occured, in C<$!>) - for most requests the syscall return code (e.g.
291most syscalls return C<-1> on error, unlike perl, which usually delivers
292"false").
293
294Some requests (such as C<aio_readdir>) pass the actual results and
295communicate failures by passing C<undef>.
233 296
234All functions expecting a filehandle keep a copy of the filehandle 297All functions expecting a filehandle keep a copy of the filehandle
235internally until the request has finished. 298internally until the request has finished.
236 299
237All functions return request objects of type L<IO::AIO::REQ> that allow 300All functions return request objects of type L<IO::AIO::REQ> that allow
238further manipulation of those requests while they are in-flight. 301further manipulation of those requests while they are in-flight.
239 302
240The pathnames you pass to these routines I<must> be absolute and 303The pathnames you pass to these routines I<should> be absolute. The
241encoded as octets. The reason for the former is that at the time the 304reason for this is that at the time the request is being executed, the
242request is being executed, the current working directory could have 305current working directory could have changed. Alternatively, you can
243changed. Alternatively, you can make sure that you never change the 306make sure that you never change the current working directory anywhere
244current working directory anywhere in the program and then use relative 307in the program and then use relative paths. You can also take advantage
245paths. 308of IO::AIOs working directory abstraction, that lets you specify paths
309relative to some previously-opened "working directory object" - see the
310description of the C<IO::AIO::WD> class later in this document.
246 311
247To encode pathnames as octets, either make sure you either: a) always pass 312To encode pathnames as octets, either make sure you either: a) always pass
248in filenames you got from outside (command line, readdir etc.) without 313in filenames you got from outside (command line, readdir etc.) without
249tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 314tinkering, b) are in your native filesystem encoding, c) use the Encode
250your pathnames to the locale (or other) encoding in effect in the user 315module and encode your pathnames to the locale (or other) encoding in
251environment, d) use Glib::filename_from_unicode on unicode filenames or e) 316effect in the user environment, d) use Glib::filename_from_unicode on
252use something else to ensure your scalar has the correct contents. 317unicode filenames or e) use something else to ensure your scalar has the
318correct contents.
253 319
254This works, btw. independent of the internal UTF-8 bit, which IO::AIO 320This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255handles correctly whether it is set or not. 321handles correctly whether it is set or not.
322
323=head2 AIO REQUEST FUNCTIONS
256 324
257=over 4 325=over 4
258 326
259=item $prev_pri = aioreq_pri [$pri] 327=item $prev_pri = aioreq_pri [$pri]
260 328
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307by the umask in effect then the request is being executed, so better never 375by the umask in effect then the request is being executed, so better never
308change the umask. 376change the umask.
309 377
310Example: 378Example:
311 379
312 aio_open "/etc/passwd", O_RDONLY, 0, sub { 380 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313 if ($_[0]) { 381 if ($_[0]) {
314 print "open successful, fh is $_[0]\n"; 382 print "open successful, fh is $_[0]\n";
315 ... 383 ...
316 } else { 384 } else {
317 die "open failed: $!\n"; 385 die "open failed: $!\n";
318 } 386 }
319 }; 387 };
320 388
389In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
390C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
391following POSIX and non-POSIX constants are available (missing ones on
392your system are, as usual, C<0>):
393
394C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
395C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
396C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
397
321 398
322=item aio_close $fh, $callback->($status) 399=item aio_close $fh, $callback->($status)
323 400
324Asynchronously close a file and call the callback with the result 401Asynchronously close a file and call the callback with the result
325code. 402code.
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333 410
334Or in other words: the file descriptor will be closed, but it will not be 411Or in other words: the file descriptor will be closed, but it will not be
335free for reuse until the perl filehandle is closed. 412free for reuse until the perl filehandle is closed.
336 413
337=cut 414=cut
415
416=item aio_seek $fh, $offset, $whence, $callback->($offs)
417
418Seeks the filehandle to the new C<$offset>, similarly to perl's
419C<sysseek>. The C<$whence> can use the traditional values (C<0> for
420C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
421C<IO::AIO::SEEK_END>).
422
423The resulting absolute offset will be passed to the callback, or C<-1> in
424case of an error.
425
426In theory, the C<$whence> constants could be different than the
427corresponding values from L<Fcntl>, but perl guarantees they are the same,
428so don't panic.
338 429
339=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 430=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340 431
341=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 432=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342 433
… …
375 466
376Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 467Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377reading at byte offset C<$in_offset>, and starts writing at the current 468reading at byte offset C<$in_offset>, and starts writing at the current
378file offset of C<$out_fh>. Because of that, it is not safe to issue more 469file offset of C<$out_fh>. Because of that, it is not safe to issue more
379than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 470than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380other. 471other. The same C<$in_fh> works fine though, as this function does not
472move or use the file offset of C<$in_fh>.
381 473
474Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
475are written, and there is no way to find out how many more bytes have been
476read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
477number of bytes written to C<$out_fh>. Only if the result value equals
478C<$length> one can assume that C<$length> bytes have been read.
479
480Unlike with other C<aio_> functions, it makes a lot of sense to use
481C<aio_sendfile> on non-blocking sockets, as long as one end (typically
482the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
483the socket I/O will be non-blocking. Note, however, that you can run
484into a trap where C<aio_sendfile> reads some data with readahead, then
485fails to write all data, and when the socket is ready the next time, the
486data in the cache is already lost, forcing C<aio_sendfile> to again hit
487the disk. Explicit C<aio_read> + C<aio_write> let's you better control
488resource usage.
489
382This call tries to make use of a native C<sendfile> syscall to provide 490This call tries to make use of a native C<sendfile>-like syscall to
383zero-copy operation. For this to work, C<$out_fh> should refer to a 491provide zero-copy operation. For this to work, C<$out_fh> should refer to
384socket, and C<$in_fh> should refer to mmap'able file. 492a socket, and C<$in_fh> should refer to an mmap'able file.
385 493
386If the native sendfile call fails or is not implemented, it will be 494If a native sendfile cannot be found or it fails with C<ENOSYS>,
387emulated, so you can call C<aio_sendfile> on any type of filehandle 495C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
496C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
388regardless of the limitations of the operating system. 497type of filehandle regardless of the limitations of the operating system.
389 498
390Please note, however, that C<aio_sendfile> can read more bytes from 499As native sendfile syscalls (as practically any non-POSIX interface hacked
391C<$in_fh> than are written, and there is no way to find out how many 500together in a hurry to improve benchmark numbers) tend to be rather buggy
392bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 501on many systems, this implementation tries to work around some known bugs
393provides the number of bytes written to C<$out_fh>. Only if the result 502in Linux and FreeBSD kernels (probably others, too), but that might fail,
394value equals C<$length> one can assume that C<$length> bytes have been 503so you really really should check the return value of C<aio_sendfile> -
395read. 504fewre bytes than expected might have been transferred.
396 505
397 506
398=item aio_readahead $fh,$offset,$length, $callback->($retval) 507=item aio_readahead $fh,$offset,$length, $callback->($retval)
399 508
400C<aio_readahead> populates the page cache with data from a file so that 509C<aio_readahead> populates the page cache with data from a file so that
… …
423 532
424Currently, the stats are always 64-bit-stats, i.e. instead of returning an 533Currently, the stats are always 64-bit-stats, i.e. instead of returning an
425error when stat'ing a large file, the results will be silently truncated 534error when stat'ing a large file, the results will be silently truncated
426unless perl itself is compiled with large file support. 535unless perl itself is compiled with large file support.
427 536
537To help interpret the mode and dev/rdev stat values, IO::AIO offers the
538following constants and functions (if not implemented, the constants will
539be C<0> and the functions will either C<croak> or fall back on traditional
540behaviour).
541
542C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
543C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
544C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
545
428Example: Print the length of F</etc/passwd>: 546Example: Print the length of F</etc/passwd>:
429 547
430 aio_stat "/etc/passwd", sub { 548 aio_stat "/etc/passwd", sub {
431 $_[0] and die "stat failed: $!"; 549 $_[0] and die "stat failed: $!";
432 print "size is ", -s _, "\n"; 550 print "size is ", -s _, "\n";
433 }; 551 };
434 552
435 553
554=item aio_statvfs $fh_or_path, $callback->($statvfs)
555
556Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
557whether a file handle or path was passed.
558
559On success, the callback is passed a hash reference with the following
560members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
561C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
562is passed.
563
564The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
565C<ST_NOSUID>.
566
567The following non-POSIX IO::AIO::ST_* flag masks are defined to
568their correct value when available, or to C<0> on systems that do
569not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
570C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
571C<ST_NODIRATIME> and C<ST_RELATIME>.
572
573Example: stat C</wd> and dump out the data if successful.
574
575 aio_statvfs "/wd", sub {
576 my $f = $_[0]
577 or die "statvfs: $!";
578
579 use Data::Dumper;
580 say Dumper $f;
581 };
582
583 # result:
584 {
585 bsize => 1024,
586 bfree => 4333064312,
587 blocks => 10253828096,
588 files => 2050765568,
589 flag => 4096,
590 favail => 2042092649,
591 bavail => 4333064312,
592 ffree => 2042092649,
593 namemax => 255,
594 frsize => 1024,
595 fsid => 1810
596 }
597
598
436=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 599=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437 600
438Works like perl's C<utime> function (including the special case of $atime 601Works like perl's C<utime> function (including the special case of $atime
439and $mtime being undef). Fractional times are supported if the underlying 602and $mtime being undef). Fractional times are supported if the underlying
440syscalls support them. 603syscalls support them.
… …
478 641
479Asynchronously unlink (delete) a file and call the callback with the 642Asynchronously unlink (delete) a file and call the callback with the
480result code. 643result code.
481 644
482 645
483=item aio_mknod $path, $mode, $dev, $callback->($status) 646=item aio_mknod $pathname, $mode, $dev, $callback->($status)
484 647
485[EXPERIMENTAL] 648[EXPERIMENTAL]
486 649
487Asynchronously create a device node (or fifo). See mknod(2). 650Asynchronously create a device node (or fifo). See mknod(2).
488 651
489The only (POSIX-) portable way of calling this function is: 652The only (POSIX-) portable way of calling this function is:
490 653
491 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 654 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492 655
656See C<aio_stat> for info about some potentially helpful extra constants
657and functions.
493 658
494=item aio_link $srcpath, $dstpath, $callback->($status) 659=item aio_link $srcpath, $dstpath, $callback->($status)
495 660
496Asynchronously create a new link to the existing object at C<$srcpath> at 661Asynchronously create a new link to the existing object at C<$srcpath> at
497the path C<$dstpath> and call the callback with the result code. 662the path C<$dstpath> and call the callback with the result code.
… …
501 666
502Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 667Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
503the path C<$dstpath> and call the callback with the result code. 668the path C<$dstpath> and call the callback with the result code.
504 669
505 670
506=item aio_readlink $path, $callback->($link) 671=item aio_readlink $pathname, $callback->($link)
507 672
508Asynchronously read the symlink specified by C<$path> and pass it to 673Asynchronously read the symlink specified by C<$path> and pass it to
509the callback. If an error occurs, nothing or undef gets passed to the 674the callback. If an error occurs, nothing or undef gets passed to the
510callback. 675callback.
511 676
512 677
678=item aio_realpath $pathname, $callback->($path)
679
680Asynchronously make the path absolute and resolve any symlinks in
681C<$path>. The resulting path only consists of directories (Same as
682L<Cwd::realpath>).
683
684This request can be used to get the absolute path of the current working
685directory by passing it a path of F<.> (a single dot).
686
687
513=item aio_rename $srcpath, $dstpath, $callback->($status) 688=item aio_rename $srcpath, $dstpath, $callback->($status)
514 689
515Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 690Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
516rename(2) and call the callback with the result code. 691rename(2) and call the callback with the result code.
517 692
… …
539array-ref with the filenames. 714array-ref with the filenames.
540 715
541 716
542=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) 717=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
543 718
544Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune 719Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
545behaviour and output format. In case of an error, C<$entries> will be 720tune behaviour and output format. In case of an error, C<$entries> will be
546C<undef>. 721C<undef>.
547 722
548The flags are a combination of the following constants, ORed together (the 723The flags are a combination of the following constants, ORed together (the
549flags will also be passed to the callback, possibly modified): 724flags will also be passed to the callback, possibly modified):
550 725
551=over 4 726=over 4
552 727
553=item IO::AIO::READDIR_DENTS 728=item IO::AIO::READDIR_DENTS
554 729
555When this flag is off, then the callback gets an arrayref with of names 730When this flag is off, then the callback gets an arrayref consisting of
556only (as with C<aio_readdir>), otherwise it gets an arrayref with 731names only (as with C<aio_readdir>), otherwise it gets an arrayref with
557C<[$name, $type, $inode]> arrayrefs, each describing a single directory 732C<[$name, $type, $inode]> arrayrefs, each describing a single directory
558entry in more detail. 733entry in more detail.
559 734
560C<$name> is the name of the entry. 735C<$name> is the name of the entry.
561 736
… …
574systems that do not deliver the inode information. 749systems that do not deliver the inode information.
575 750
576=item IO::AIO::READDIR_DIRS_FIRST 751=item IO::AIO::READDIR_DIRS_FIRST
577 752
578When this flag is set, then the names will be returned in an order where 753When this flag is set, then the names will be returned in an order where
579likely directories come first. This is useful when you need to quickly 754likely directories come first, in optimal stat order. This is useful when
580find directories, or you want to find all directories while avoiding to 755you need to quickly find directories, or you want to find all directories
581stat() each entry. 756while avoiding to stat() each entry.
582 757
583If the system returns type information in readdir, then this is used 758If the system returns type information in readdir, then this is used
584to find directories directly. Otherwise, likely directories are files 759to find directories directly. Otherwise, likely directories are names
585beginning with ".", or otherwise files with no dots, of which files with 760beginning with ".", or otherwise names with no dots, of which names with
586short names are tried first. 761short names are tried first.
587 762
588=item IO::AIO::READDIR_STAT_ORDER 763=item IO::AIO::READDIR_STAT_ORDER
589 764
590When this flag is set, then the names will be returned in an order 765When this flag is set, then the names will be returned in an order
… …
597 772
598=item IO::AIO::READDIR_FOUND_UNKNOWN 773=item IO::AIO::READDIR_FOUND_UNKNOWN
599 774
600This flag should not be set when calling C<aio_readdirx>. Instead, it 775This flag should not be set when calling C<aio_readdirx>. Instead, it
601is being set by C<aio_readdirx>, when any of the C<$type>'s found were 776is being set by C<aio_readdirx>, when any of the C<$type>'s found were
602C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all 777C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
603C<$type>'s are known, which can be used to speed up some algorithms. 778C<$type>'s are known, which can be used to speed up some algorithms.
604 779
605=back 780=back
606 781
607 782
608=item aio_load $path, $data, $callback->($status) 783=item aio_load $pathname, $data, $callback->($status)
609 784
610This is a composite request that tries to fully load the given file into 785This is a composite request that tries to fully load the given file into
611memory. Status is the same as with aio_read. 786memory. Status is the same as with aio_read.
612 787
613=cut 788=cut
… …
635 810
636=item aio_copy $srcpath, $dstpath, $callback->($status) 811=item aio_copy $srcpath, $dstpath, $callback->($status)
637 812
638Try to copy the I<file> (directories not supported as either source or 813Try to copy the I<file> (directories not supported as either source or
639destination) from C<$srcpath> to C<$dstpath> and call the callback with 814destination) from C<$srcpath> to C<$dstpath> and call the callback with
640the C<0> (error) or C<-1> ok. 815a status of C<0> (ok) or C<-1> (error, see C<$!>).
641 816
642This is a composite request that creates the destination file with 817This is a composite request that creates the destination file with
643mode 0200 and copies the contents of the source file into it using 818mode 0200 and copies the contents of the source file into it using
644C<aio_sendfile>, followed by restoring atime, mtime, access mode and 819C<aio_sendfile>, followed by restoring atime, mtime, access mode and
645uid/gid, in that order. 820uid/gid, in that order.
… …
657 my $grp = aio_group $cb; 832 my $grp = aio_group $cb;
658 833
659 aioreq_pri $pri; 834 aioreq_pri $pri;
660 add $grp aio_open $src, O_RDONLY, 0, sub { 835 add $grp aio_open $src, O_RDONLY, 0, sub {
661 if (my $src_fh = $_[0]) { 836 if (my $src_fh = $_[0]) {
662 my @stat = stat $src_fh; # hmm, might bock over nfs? 837 my @stat = stat $src_fh; # hmm, might block over nfs?
663 838
664 aioreq_pri $pri; 839 aioreq_pri $pri;
665 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { 840 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
666 if (my $dst_fh = $_[0]) { 841 if (my $dst_fh = $_[0]) {
667 aioreq_pri $pri; 842 aioreq_pri $pri;
… …
714 889
715=item aio_move $srcpath, $dstpath, $callback->($status) 890=item aio_move $srcpath, $dstpath, $callback->($status)
716 891
717Try to move the I<file> (directories not supported as either source or 892Try to move the I<file> (directories not supported as either source or
718destination) from C<$srcpath> to C<$dstpath> and call the callback with 893destination) from C<$srcpath> to C<$dstpath> and call the callback with
719the C<0> (error) or C<-1> ok. 894a status of C<0> (ok) or C<-1> (error, see C<$!>).
720 895
721This is a composite request that tries to rename(2) the file first; if 896This is a composite request that tries to rename(2) the file first; if
722rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if 897rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
723that is successful, unlinks the C<$srcpath>. 898that is successful, unlinks the C<$srcpath>.
724 899
… …
735 if ($_[0] && $! == EXDEV) { 910 if ($_[0] && $! == EXDEV) {
736 aioreq_pri $pri; 911 aioreq_pri $pri;
737 add $grp aio_copy $src, $dst, sub { 912 add $grp aio_copy $src, $dst, sub {
738 $grp->result ($_[0]); 913 $grp->result ($_[0]);
739 914
740 if (!$_[0]) { 915 unless ($_[0]) {
741 aioreq_pri $pri; 916 aioreq_pri $pri;
742 add $grp aio_unlink $src; 917 add $grp aio_unlink $src;
743 } 918 }
744 }; 919 };
745 } else { 920 } else {
… …
748 }; 923 };
749 924
750 $grp 925 $grp
751} 926}
752 927
753=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 928=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
754 929
755Scans a directory (similar to C<aio_readdir>) but additionally tries to 930Scans a directory (similar to C<aio_readdir>) but additionally tries to
756efficiently separate the entries of directory C<$path> into two sets of 931efficiently separate the entries of directory C<$path> into two sets of
757names, directories you can recurse into (directories), and ones you cannot 932names, directories you can recurse into (directories), and ones you cannot
758recurse into (everything else, including symlinks to directories). 933recurse into (everything else, including symlinks to directories).
… …
789Then entries will be sorted into likely directories a non-initial dot 964Then entries will be sorted into likely directories a non-initial dot
790currently) and likely non-directories (see C<aio_readdirx>). Then every 965currently) and likely non-directories (see C<aio_readdirx>). Then every
791entry plus an appended C</.> will be C<stat>'ed, likely directories first, 966entry plus an appended C</.> will be C<stat>'ed, likely directories first,
792in order of their inode numbers. If that succeeds, it assumes that the 967in order of their inode numbers. If that succeeds, it assumes that the
793entry is a directory or a symlink to directory (which will be checked 968entry is a directory or a symlink to directory (which will be checked
794seperately). This is often faster than stat'ing the entry itself because 969separately). This is often faster than stat'ing the entry itself because
795filesystems might detect the type of the entry without reading the inode 970filesystems might detect the type of the entry without reading the inode
796data (e.g. ext2fs filetype feature), even on systems that cannot return 971data (e.g. ext2fs filetype feature), even on systems that cannot return
797the filetype information on readdir. 972the filetype information on readdir.
798 973
799If the known number of directories (link count - 2) has been reached, the 974If the known number of directories (link count - 2) has been reached, the
… …
815 990
816 my $grp = aio_group $cb; 991 my $grp = aio_group $cb;
817 992
818 $maxreq = 4 if $maxreq <= 0; 993 $maxreq = 4 if $maxreq <= 0;
819 994
820 # stat once 995 # get a wd object
821 aioreq_pri $pri; 996 aioreq_pri $pri;
822 add $grp aio_stat $path, sub { 997 add $grp aio_wd $path, sub {
998 $_[0]
823 return $grp->result () if $_[0]; 999 or return $grp->result ();
824 my $now = time;
825 my $hash1 = join ":", (stat _)[0,1,3,7,9];
826 1000
827 # read the directory entries 1001 my $wd = [shift, "."];
1002
1003 # stat once
828 aioreq_pri $pri; 1004 aioreq_pri $pri;
829 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { 1005 add $grp aio_stat $wd, sub {
830 my $entries = shift
831 or return $grp->result (); 1006 return $grp->result () if $_[0];
1007 my $now = time;
1008 my $hash1 = join ":", (stat _)[0,1,3,7,9];
832 1009
833 # stat the dir another time 1010 # read the directory entries
834 aioreq_pri $pri; 1011 aioreq_pri $pri;
1012 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
1013 my $entries = shift
1014 or return $grp->result ();
1015
1016 # stat the dir another time
1017 aioreq_pri $pri;
835 add $grp aio_stat $path, sub { 1018 add $grp aio_stat $wd, sub {
836 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1019 my $hash2 = join ":", (stat _)[0,1,3,7,9];
837 1020
838 my $ndirs; 1021 my $ndirs;
839 1022
840 # take the slow route if anything looks fishy 1023 # take the slow route if anything looks fishy
841 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1024 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
842 $ndirs = -1; 1025 $ndirs = -1;
843 } else { 1026 } else {
844 # if nlink == 2, we are finished 1027 # if nlink == 2, we are finished
845 # for non-posix-fs's, we rely on nlink < 2 1028 # for non-posix-fs's, we rely on nlink < 2
846 $ndirs = (stat _)[3] - 2 1029 $ndirs = (stat _)[3] - 2
847 or return $grp->result ([], $entries); 1030 or return $grp->result ([], $entries);
848 } 1031 }
849 1032
850 my (@dirs, @nondirs); 1033 my (@dirs, @nondirs);
851 1034
852 my $statgrp = add $grp aio_group sub { 1035 my $statgrp = add $grp aio_group sub {
853 $grp->result (\@dirs, \@nondirs); 1036 $grp->result (\@dirs, \@nondirs);
854 }; 1037 };
855 1038
856 limit $statgrp $maxreq; 1039 limit $statgrp $maxreq;
857 feed $statgrp sub { 1040 feed $statgrp sub {
858 return unless @$entries; 1041 return unless @$entries;
859 my $entry = shift @$entries; 1042 my $entry = shift @$entries;
860 1043
861 aioreq_pri $pri; 1044 aioreq_pri $pri;
1045 $wd->[1] = "$entry/.";
862 add $statgrp aio_stat "$path/$entry/.", sub { 1046 add $statgrp aio_stat $wd, sub {
863 if ($_[0] < 0) { 1047 if ($_[0] < 0) {
864 push @nondirs, $entry; 1048 push @nondirs, $entry;
865 } else { 1049 } else {
866 # need to check for real directory 1050 # need to check for real directory
867 aioreq_pri $pri; 1051 aioreq_pri $pri;
1052 $wd->[1] = $entry;
868 add $statgrp aio_lstat "$path/$entry", sub { 1053 add $statgrp aio_lstat $wd, sub {
869 if (-d _) { 1054 if (-d _) {
870 push @dirs, $entry; 1055 push @dirs, $entry;
871 1056
872 unless (--$ndirs) { 1057 unless (--$ndirs) {
873 push @nondirs, @$entries; 1058 push @nondirs, @$entries;
874 feed $statgrp; 1059 feed $statgrp;
1060 }
1061 } else {
1062 push @nondirs, $entry;
875 } 1063 }
876 } else {
877 push @nondirs, $entry;
878 } 1064 }
879 } 1065 }
880 } 1066 };
881 }; 1067 };
882 }; 1068 };
883 }; 1069 };
884 }; 1070 };
885 }; 1071 };
886 1072
887 $grp 1073 $grp
888} 1074}
889 1075
890=item aio_rmtree $path, $callback->($status) 1076=item aio_rmtree $pathname, $callback->($status)
891 1077
892Delete a directory tree starting (and including) C<$path>, return the 1078Delete a directory tree starting (and including) C<$path>, return the
893status of the final C<rmdir> only. This is a composite request that 1079status of the final C<rmdir> only. This is a composite request that
894uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1080uses C<aio_scandir> to recurse into and rmdir directories, and unlink
895everything else. 1081everything else.
… …
937callback with the fdatasync result code. 1123callback with the fdatasync result code.
938 1124
939If this call isn't available because your OS lacks it or it couldn't be 1125If this call isn't available because your OS lacks it or it couldn't be
940detected, it will be emulated by calling C<fsync> instead. 1126detected, it will be emulated by calling C<fsync> instead.
941 1127
1128=item aio_syncfs $fh, $callback->($status)
1129
1130Asynchronously call the syncfs syscall to sync the filesystem associated
1131to the given filehandle and call the callback with the syncfs result
1132code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1133errno to C<ENOSYS> nevertheless.
1134
942=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1135=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
943 1136
944Sync the data portion of the file specified by C<$offset> and C<$length> 1137Sync the data portion of the file specified by C<$offset> and C<$length>
945to disk (but NOT the metadata), by calling the Linux-specific 1138to disk (but NOT the metadata), by calling the Linux-specific
946sync_file_range call. If sync_file_range is not available or it returns 1139sync_file_range call. If sync_file_range is not available or it returns
… …
949C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, 1142C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
950C<IO::AIO::SYNC_FILE_RANGE_WRITE> and 1143C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
951C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range 1144C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
952manpage for details. 1145manpage for details.
953 1146
954=item aio_pathsync $path, $callback->($status) 1147=item aio_pathsync $pathname, $callback->($status)
955 1148
956This request tries to open, fsync and close the given path. This is a 1149This request tries to open, fsync and close the given path. This is a
957composite request intended to sync directories after directory operations 1150composite request intended to sync directories after directory operations
958(E.g. rename). This might not work on all operating systems or have any 1151(E.g. rename). This might not work on all operating systems or have any
959specific effect, but usually it makes sure that directory changes get 1152specific effect, but usually it makes sure that directory changes get
960written to disc. It works for anything that can be opened for read-only, 1153written to disc. It works for anything that can be opened for read-only,
961not just directories. 1154not just directories.
1155
1156Future versions of this function might fall back to other methods when
1157C<fsync> on the directory fails (such as calling C<sync>).
962 1158
963Passes C<0> when everything went ok, and C<-1> on error. 1159Passes C<0> when everything went ok, and C<-1> on error.
964 1160
965=cut 1161=cut
966 1162
… …
987 }; 1183 };
988 1184
989 $grp 1185 $grp
990} 1186}
991 1187
1188=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1189
1190This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1191scalars (see the C<IO::AIO::mmap> function, although it also works on data
1192scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1193scalar must only be modified in-place while an aio operation is pending on
1194it).
1195
1196It calls the C<msync> function of your OS, if available, with the memory
1197area starting at C<$offset> in the string and ending C<$length> bytes
1198later. If C<$length> is negative, counts from the end, and if C<$length>
1199is C<undef>, then it goes till the end of the string. The flags can be
1200a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
1201C<IO::AIO::MS_SYNC>.
1202
1203=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1204
1205This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1206scalars.
1207
1208It touches (reads or writes) all memory pages in the specified
1209range inside the scalar. All caveats and parameters are the same
1210as for C<aio_msync>, above, except for flags, which must be either
1211C<0> (which reads all pages and ensures they are instantiated) or
1212C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
1213writing an octet from it, which dirties the page).
1214
1215=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1216
1217This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1218scalars.
1219
1220It reads in all the pages of the underlying storage into memory (if any)
1221and locks them, so they are not getting swapped/paged out or removed.
1222
1223If C<$length> is undefined, then the scalar will be locked till the end.
1224
1225On systems that do not implement C<mlock>, this function returns C<-1>
1226and sets errno to C<ENOSYS>.
1227
1228Note that the corresponding C<munlock> is synchronous and is
1229documented under L<MISCELLANEOUS FUNCTIONS>.
1230
1231Example: open a file, mmap and mlock it - both will be undone when
1232C<$data> gets destroyed.
1233
1234 open my $fh, "<", $path or die "$path: $!";
1235 my $data;
1236 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1237 aio_mlock $data; # mlock in background
1238
1239=item aio_mlockall $flags, $callback->($status)
1240
1241Calls the C<mlockall> function with the given C<$flags> (a combination of
1242C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1243
1244On systems that do not implement C<mlockall>, this function returns C<-1>
1245and sets errno to C<ENOSYS>.
1246
1247Note that the corresponding C<munlockall> is synchronous and is
1248documented under L<MISCELLANEOUS FUNCTIONS>.
1249
1250Example: asynchronously lock all current and future pages into memory.
1251
1252 aio_mlockall IO::AIO::MCL_FUTURE;
1253
992=item aio_group $callback->(...) 1254=item aio_group $callback->(...)
993 1255
994This is a very special aio request: Instead of doing something, it is a 1256This is a very special aio request: Instead of doing something, it is a
995container for other aio requests, which is useful if you want to bundle 1257container for other aio requests, which is useful if you want to bundle
996many requests into a single, composite, request with a definite callback 1258many requests into a single, composite, request with a definite callback
… …
1032like sleep and file handle readable/writable, the overhead this creates is 1294like sleep and file handle readable/writable, the overhead this creates is
1033immense (it blocks a thread for a long time) so do not use this function 1295immense (it blocks a thread for a long time) so do not use this function
1034except to put your application under artificial I/O pressure. 1296except to put your application under artificial I/O pressure.
1035 1297
1036=back 1298=back
1299
1300
1301=head2 IO::AIO::WD - multiple working directories
1302
1303Your process only has one current working directory, which is used by all
1304threads. This makes it hard to use relative paths (some other component
1305could call C<chdir> at any time, and it is hard to control when the path
1306will be used by IO::AIO).
1307
1308One solution for this is to always use absolute paths. This usually works,
1309but can be quite slow (the kernel has to walk the whole path on every
1310access), and can also be a hassle to implement.
1311
1312Newer POSIX systems have a number of functions (openat, fdopendir,
1313futimensat and so on) that make it possible to specify working directories
1314per operation.
1315
1316For portability, and because the clowns who "designed", or shall I write,
1317perpetrated this new interface were obviously half-drunk, this abstraction
1318cannot be perfect, though.
1319
1320IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1321object. This object stores the canonicalised, absolute version of the
1322path, and on systems that allow it, also a directory file descriptor.
1323
1324Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1325or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1326object and a pathname instead (or the IO::AIO::WD object alone, which
1327gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1328IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1329to that IO::AIO::WD object.
1330
1331For example, to get a wd object for F</etc> and then stat F<passwd>
1332inside, you would write:
1333
1334 aio_wd "/etc", sub {
1335 my $etcdir = shift;
1336
1337 # although $etcdir can be undef on error, there is generally no reason
1338 # to check for errors here, as aio_stat will fail with ENOENT
1339 # when $etcdir is undef.
1340
1341 aio_stat [$etcdir, "passwd"], sub {
1342 # yay
1343 };
1344 };
1345
1346That C<aio_wd> is a request and not a normal function shows that creating
1347an IO::AIO::WD object is itself a potentially blocking operation, which is
1348why it is done asynchronously.
1349
1350To stat the directory obtained with C<aio_wd> above, one could write
1351either of the following three request calls:
1352
1353 aio_lstat "/etc" , sub { ... # pathname as normal string
1354 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1355 aio_lstat $wd , sub { ... # shorthand for the previous
1356
1357As with normal pathnames, IO::AIO keeps a copy of the working directory
1358object and the pathname string, so you could write the following without
1359causing any issues due to C<$path> getting reused:
1360
1361 my $path = [$wd, undef];
1362
1363 for my $name (qw(abc def ghi)) {
1364 $path->[1] = $name;
1365 aio_stat $path, sub {
1366 # ...
1367 };
1368 }
1369
1370There are some caveats: when directories get renamed (or deleted), the
1371pathname string doesn't change, so will point to the new directory (or
1372nowhere at all), while the directory fd, if available on the system,
1373will still point to the original directory. Most functions accepting a
1374pathname will use the directory fd on newer systems, and the string on
1375older systems. Some functions (such as realpath) will always rely on the
1376string form of the pathname.
1377
1378So this fucntionality is mainly useful to get some protection against
1379C<chdir>, to easily get an absolute path out of a relative path for future
1380reference, and to speed up doing many operations in the same directory
1381(e.g. when stat'ing all files in a directory).
1382
1383The following functions implement this working directory abstraction:
1384
1385=over 4
1386
1387=item aio_wd $pathname, $callback->($wd)
1388
1389Asynchonously canonicalise the given pathname and convert it to an
1390IO::AIO::WD object representing it. If possible and supported on the
1391system, also open a directory fd to speed up pathname resolution relative
1392to this working directory.
1393
1394If something goes wrong, then C<undef> is passwd to the callback instead
1395of a working directory object and C<$!> is set appropriately. Since
1396passing C<undef> as working directory component of a pathname fails the
1397request with C<ENOENT>, there is often no need for error checking in the
1398C<aio_wd> callback, as future requests using the value will fail in the
1399expected way.
1400
1401If this call isn't available because your OS lacks it or it couldn't be
1402detected, it will be emulated by calling C<fsync> instead.
1403
1404=item IO::AIO::CWD
1405
1406This is a compiletime constant (object) that represents the process
1407current working directory.
1408
1409Specifying this object as working directory object for a pathname is as
1410if the pathname would be specified directly, without a directory object,
1411e.g., these calls are functionally identical:
1412
1413 aio_stat "somefile", sub { ... };
1414 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1415
1416=back
1417
1037 1418
1038=head2 IO::AIO::REQ CLASS 1419=head2 IO::AIO::REQ CLASS
1039 1420
1040All non-aggregate C<aio_*> functions return an object of this class when 1421All non-aggregate C<aio_*> functions return an object of this class when
1041called in non-void context. 1422called in non-void context.
… …
1131=item $grp->cancel_subs 1512=item $grp->cancel_subs
1132 1513
1133Cancel all subrequests and clears any feeder, but not the group request 1514Cancel all subrequests and clears any feeder, but not the group request
1134itself. Useful when you queued a lot of events but got a result early. 1515itself. Useful when you queued a lot of events but got a result early.
1135 1516
1517The group request will finish normally (you cannot add requests to the
1518group).
1519
1136=item $grp->result (...) 1520=item $grp->result (...)
1137 1521
1138Set the result value(s) that will be passed to the group callback when all 1522Set the result value(s) that will be passed to the group callback when all
1139subrequests have finished and set the groups errno to the current value 1523subrequests have finished and set the groups errno to the current value
1140of errno (just like calling C<errno> without an error number). By default, 1524of errno (just like calling C<errno> without an error number). By default,
… …
1156 1540
1157Sets a feeder/generator on this group: every group can have an attached 1541Sets a feeder/generator on this group: every group can have an attached
1158generator that generates requests if idle. The idea behind this is that, 1542generator that generates requests if idle. The idea behind this is that,
1159although you could just queue as many requests as you want in a group, 1543although you could just queue as many requests as you want in a group,
1160this might starve other requests for a potentially long time. For example, 1544this might starve other requests for a potentially long time. For example,
1161C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, 1545C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1162delaying any later requests for a long time. 1546requests, delaying any later requests for a long time.
1163 1547
1164To avoid this, and allow incremental generation of requests, you can 1548To avoid this, and allow incremental generation of requests, you can
1165instead a group and set a feeder on it that generates those requests. The 1549instead a group and set a feeder on it that generates those requests. The
1166feed callback will be called whenever there are few enough (see C<limit>, 1550feed callback will be called whenever there are few enough (see C<limit>,
1167below) requests active in the group itself and is expected to queue more 1551below) requests active in the group itself and is expected to queue more
… …
1208=over 4 1592=over 4
1209 1593
1210=item $fileno = IO::AIO::poll_fileno 1594=item $fileno = IO::AIO::poll_fileno
1211 1595
1212Return the I<request result pipe file descriptor>. This filehandle must be 1596Return the I<request result pipe file descriptor>. This filehandle must be
1213polled for reading by some mechanism outside this module (e.g. Event or 1597polled for reading by some mechanism outside this module (e.g. EV, Glib,
1214select, see below or the SYNOPSIS). If the pipe becomes readable you have 1598select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1215to call C<poll_cb> to check the results. 1599you have to call C<poll_cb> to check the results.
1216 1600
1217See C<poll_cb> for an example. 1601See C<poll_cb> for an example.
1218 1602
1219=item IO::AIO::poll_cb 1603=item IO::AIO::poll_cb
1220 1604
1221Process some outstanding events on the result pipe. You have to call this 1605Process some outstanding events on the result pipe. You have to call
1222regularly. Returns C<0> if all events could be processed, or C<-1> if it 1606this regularly. Returns C<0> if all events could be processed (or there
1223returned earlier for whatever reason. Returns immediately when no events 1607were no events to process), or C<-1> if it returned earlier for whatever
1224are outstanding. The amount of events processed depends on the settings of 1608reason. Returns immediately when no events are outstanding. The amount of
1225C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1609events processed depends on the settings of C<IO::AIO::max_poll_req> and
1610C<IO::AIO::max_poll_time>.
1226 1611
1227If not all requests were processed for whatever reason, the filehandle 1612If not all requests were processed for whatever reason, the filehandle
1228will still be ready when C<poll_cb> returns, so normally you don't have to 1613will still be ready when C<poll_cb> returns, so normally you don't have to
1229do anything special to have it called later. 1614do anything special to have it called later.
1230 1615
1616Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1617ready, it can be beneficial to call this function from loops which submit
1618a lot of requests, to make sure the results get processed when they become
1619available and not just when the loop is finished and the event loop takes
1620over again. This function returns very fast when there are no outstanding
1621requests.
1622
1231Example: Install an Event watcher that automatically calls 1623Example: Install an Event watcher that automatically calls
1232IO::AIO::poll_cb with high priority: 1624IO::AIO::poll_cb with high priority (more examples can be found in the
1625SYNOPSIS section, at the top of this document):
1233 1626
1234 Event->io (fd => IO::AIO::poll_fileno, 1627 Event->io (fd => IO::AIO::poll_fileno,
1235 poll => 'r', async => 1, 1628 poll => 'r', async => 1,
1236 cb => \&IO::AIO::poll_cb); 1629 cb => \&IO::AIO::poll_cb);
1630
1631=item IO::AIO::poll_wait
1632
1633If there are any outstanding requests and none of them in the result
1634phase, wait till the result filehandle becomes ready for reading (simply
1635does a C<select> on the filehandle. This is useful if you want to
1636synchronously wait for some requests to finish).
1637
1638See C<nreqs> for an example.
1639
1640=item IO::AIO::poll
1641
1642Waits until some requests have been handled.
1643
1644Returns the number of requests processed, but is otherwise strictly
1645equivalent to:
1646
1647 IO::AIO::poll_wait, IO::AIO::poll_cb
1648
1649=item IO::AIO::flush
1650
1651Wait till all outstanding AIO requests have been handled.
1652
1653Strictly equivalent to:
1654
1655 IO::AIO::poll_wait, IO::AIO::poll_cb
1656 while IO::AIO::nreqs;
1237 1657
1238=item IO::AIO::max_poll_reqs $nreqs 1658=item IO::AIO::max_poll_reqs $nreqs
1239 1659
1240=item IO::AIO::max_poll_time $seconds 1660=item IO::AIO::max_poll_time $seconds
1241 1661
… …
1266 # use a low priority so other tasks have priority 1686 # use a low priority so other tasks have priority
1267 Event->io (fd => IO::AIO::poll_fileno, 1687 Event->io (fd => IO::AIO::poll_fileno,
1268 poll => 'r', nice => 1, 1688 poll => 'r', nice => 1,
1269 cb => &IO::AIO::poll_cb); 1689 cb => &IO::AIO::poll_cb);
1270 1690
1271=item IO::AIO::poll_wait
1272
1273If there are any outstanding requests and none of them in the result
1274phase, wait till the result filehandle becomes ready for reading (simply
1275does a C<select> on the filehandle. This is useful if you want to
1276synchronously wait for some requests to finish).
1277
1278See C<nreqs> for an example.
1279
1280=item IO::AIO::poll
1281
1282Waits until some requests have been handled.
1283
1284Returns the number of requests processed, but is otherwise strictly
1285equivalent to:
1286
1287 IO::AIO::poll_wait, IO::AIO::poll_cb
1288
1289=item IO::AIO::flush
1290
1291Wait till all outstanding AIO requests have been handled.
1292
1293Strictly equivalent to:
1294
1295 IO::AIO::poll_wait, IO::AIO::poll_cb
1296 while IO::AIO::nreqs;
1297
1298=back 1691=back
1299 1692
1300=head3 CONTROLLING THE NUMBER OF THREADS 1693=head3 CONTROLLING THE NUMBER OF THREADS
1301 1694
1302=over 1695=over
… …
1335 1728
1336Under normal circumstances you don't need to call this function. 1729Under normal circumstances you don't need to call this function.
1337 1730
1338=item IO::AIO::max_idle $nthreads 1731=item IO::AIO::max_idle $nthreads
1339 1732
1340Limit the number of threads (default: 4) that are allowed to idle (i.e., 1733Limit the number of threads (default: 4) that are allowed to idle
1341threads that did not get a request to process within 10 seconds). That 1734(i.e., threads that did not get a request to process within the idle
1342means if a thread becomes idle while C<$nthreads> other threads are also 1735timeout (default: 10 seconds). That means if a thread becomes idle while
1343idle, it will free its resources and exit. 1736C<$nthreads> other threads are also idle, it will free its resources and
1737exit.
1344 1738
1345This is useful when you allow a large number of threads (e.g. 100 or 1000) 1739This is useful when you allow a large number of threads (e.g. 100 or 1000)
1346to allow for extremely high load situations, but want to free resources 1740to allow for extremely high load situations, but want to free resources
1347under normal circumstances (1000 threads can easily consume 30MB of RAM). 1741under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348 1742
1349The default is probably ok in most situations, especially if thread 1743The default is probably ok in most situations, especially if thread
1350creation is fast. If thread creation is very slow on your system you might 1744creation is fast. If thread creation is very slow on your system you might
1351want to use larger values. 1745want to use larger values.
1352 1746
1747=item IO::AIO::idle_timeout $seconds
1748
1749Sets the minimum idle timeout (default 10) after which worker threads are
1750allowed to exit. SEe C<IO::AIO::max_idle>.
1751
1353=item IO::AIO::max_outstanding $maxreqs 1752=item IO::AIO::max_outstanding $maxreqs
1753
1754Sets the maximum number of outstanding requests to C<$nreqs>. If
1755you do queue up more than this number of requests, the next call to
1756C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1757C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1758longer exceeded.
1759
1760In other words, this setting does not enforce a queue limit, but can be
1761used to make poll functions block if the limit is exceeded.
1354 1762
1355This is a very bad function to use in interactive programs because it 1763This is a very bad function to use in interactive programs because it
1356blocks, and a bad way to reduce concurrency because it is inexact: Better 1764blocks, and a bad way to reduce concurrency because it is inexact: Better
1357use an C<aio_group> together with a feed callback. 1765use an C<aio_group> together with a feed callback.
1358 1766
1359Sets the maximum number of outstanding requests to C<$nreqs>. If you 1767It's main use is in scripts without an event loop - when you want to stat
1360do queue up more than this number of requests, the next call to the 1768a lot of files, you can write somehting like this:
1361C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1362function will block until the limit is no longer exceeded.
1363 1769
1364The default value is very large, so there is no practical limit on the 1770 IO::AIO::max_outstanding 32;
1365number of outstanding requests.
1366 1771
1367You can still queue as many requests as you want. Therefore, 1772 for my $path (...) {
1368C<max_outstanding> is mainly useful in simple scripts (with low values) or 1773 aio_stat $path , ...;
1369as a stop gap to shield against fatal memory overflow (with large values). 1774 IO::AIO::poll_cb;
1775 }
1776
1777 IO::AIO::flush;
1778
1779The call to C<poll_cb> inside the loop will normally return instantly, but
1780as soon as more thna C<32> reqeusts are in-flight, it will block until
1781some requests have been handled. This keeps the loop from pushing a large
1782number of C<aio_stat> requests onto the queue.
1783
1784The default value for C<max_outstanding> is very large, so there is no
1785practical limit on the number of outstanding requests.
1370 1786
1371=back 1787=back
1372 1788
1373=head3 STATISTICAL INFORMATION 1789=head3 STATISTICAL INFORMATION
1374 1790
… …
1394Returns the number of requests currently in the pending state (executed, 1810Returns the number of requests currently in the pending state (executed,
1395but not yet processed by poll_cb). 1811but not yet processed by poll_cb).
1396 1812
1397=back 1813=back
1398 1814
1815=head3 MISCELLANEOUS FUNCTIONS
1816
1817IO::AIO implements some functions that might be useful, but are not
1818asynchronous.
1819
1820=over 4
1821
1822=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1823
1824Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1825but is blocking (this makes most sense if you know the input data is
1826likely cached already and the output filehandle is set to non-blocking
1827operations).
1828
1829Returns the number of bytes copied, or C<-1> on error.
1830
1831=item IO::AIO::fadvise $fh, $offset, $len, $advice
1832
1833Simply calls the C<posix_fadvise> function (see its
1834manpage for details). The following advice constants are
1835available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1836C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1837C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1838
1839On systems that do not implement C<posix_fadvise>, this function returns
1840ENOSYS, otherwise the return value of C<posix_fadvise>.
1841
1842=item IO::AIO::madvise $scalar, $offset, $len, $advice
1843
1844Simply calls the C<posix_madvise> function (see its
1845manpage for details). The following advice constants are
1846available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1847C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1848
1849On systems that do not implement C<posix_madvise>, this function returns
1850ENOSYS, otherwise the return value of C<posix_madvise>.
1851
1852=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1853
1854Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1855$scalar (see its manpage for details). The following protect
1856constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1857C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1858
1859On systems that do not implement C<mprotect>, this function returns
1860ENOSYS, otherwise the return value of C<mprotect>.
1861
1862=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1863
1864Memory-maps a file (or anonymous memory range) and attaches it to the
1865given C<$scalar>, which will act like a string scalar.
1866
1867The only operations allowed on the scalar are C<substr>/C<vec> that don't
1868change the string length, and most read-only operations such as copying it
1869or searching it with regexes and so on.
1870
1871Anything else is unsafe and will, at best, result in memory leaks.
1872
1873The memory map associated with the C<$scalar> is automatically removed
1874when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
1875C<IO::AIO::munmap> functions are called.
1876
1877This calls the C<mmap>(2) function internally. See your system's manual
1878page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1879
1880The C<$length> must be larger than zero and smaller than the actual
1881filesize.
1882
1883C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1884C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1885
1886C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
1887C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
1888not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
1889(which is set to C<MAP_ANON> if your system only provides this
1890constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
1891C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1892C<IO::AIO::MAP_NONBLOCK>
1893
1894If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1895
1896C<$offset> is the offset from the start of the file - it generally must be
1897a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1898
1899Example:
1900
1901 use Digest::MD5;
1902 use IO::AIO;
1903
1904 open my $fh, "<verybigfile"
1905 or die "$!";
1906
1907 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1908 or die "verybigfile: $!";
1909
1910 my $fast_md5 = md5 $data;
1911
1912=item IO::AIO::munmap $scalar
1913
1914Removes a previous mmap and undefines the C<$scalar>.
1915
1916=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1917
1918Calls the C<munlock> function, undoing the effects of a previous
1919C<aio_mlock> call (see its description for details).
1920
1921=item IO::AIO::munlockall
1922
1923Calls the C<munlockall> function.
1924
1925On systems that do not implement C<munlockall>, this function returns
1926ENOSYS, otherwise the return value of C<munlockall>.
1927
1928=back
1929
1399=cut 1930=cut
1400 1931
1401min_parallel 8; 1932min_parallel 8;
1402 1933
1403END { flush } 1934END { flush }
1404 1935
14051; 19361;
1406 1937
1938=head1 EVENT LOOP INTEGRATION
1939
1940It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
1941automatically into many event loops:
1942
1943 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1944 use AnyEvent::AIO;
1945
1946You can also integrate IO::AIO manually into many event loops, here are
1947some examples of how to do this:
1948
1949 # EV integration
1950 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1951
1952 # Event integration
1953 Event->io (fd => IO::AIO::poll_fileno,
1954 poll => 'r',
1955 cb => \&IO::AIO::poll_cb);
1956
1957 # Glib/Gtk2 integration
1958 add_watch Glib::IO IO::AIO::poll_fileno,
1959 in => sub { IO::AIO::poll_cb; 1 };
1960
1961 # Tk integration
1962 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1963 readable => \&IO::AIO::poll_cb);
1964
1965 # Danga::Socket integration
1966 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1967 \&IO::AIO::poll_cb);
1968
1407=head2 FORK BEHAVIOUR 1969=head2 FORK BEHAVIOUR
1408 1970
1409This module should do "the right thing" when the process using it forks: 1971Usage of pthreads in a program changes the semantics of fork
1972considerably. Specifically, only async-safe functions can be called after
1973fork. Perl doesn't know about this, so in general, you cannot call fork
1974with defined behaviour in perl if pthreads are involved. IO::AIO uses
1975pthreads, so this applies, but many other extensions and (for inexplicable
1976reasons) perl itself often is linked against pthreads, so this limitation
1977applies to quite a lot of perls.
1410 1978
1411Before the fork, IO::AIO enters a quiescent state where no requests 1979This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1412can be added in other threads and no results will be processed. After 1980only works in the process that loaded it. Forking is fully supported, but
1413the fork the parent simply leaves the quiescent state and continues 1981using IO::AIO in the child is not.
1414request/result processing, while the child frees the request/result queue
1415(so that the requests started before the fork will only be handled in the
1416parent). Threads will be started on demand until the limit set in the
1417parent process has been reached again.
1418 1982
1419In short: the parent will, after a short pause, continue as if fork had 1983You might get around by not I<using> IO::AIO before (or after)
1420not been called, while the child will act as if IO::AIO has not been used 1984forking. You could also try to call the L<IO::AIO::reinit> function in the
1421yet. 1985child:
1986
1987=over 4
1988
1989=item IO::AIO::reinit
1990
1991Abandons all current requests and I/O threads and simply reinitialises all
1992data structures. This is not an operation supported by any standards, but
1993happens to work on GNU/Linux and some newer BSD systems.
1994
1995The only reasonable use for this function is to call it after forking, if
1996C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
1997the process will result in undefined behaviour. Calling it at any time
1998will also result in any undefined (by POSIX) behaviour.
1999
2000=back
1422 2001
1423=head2 MEMORY USAGE 2002=head2 MEMORY USAGE
1424 2003
1425Per-request usage: 2004Per-request usage:
1426 2005

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