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Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs.
Revision 1.120 by root, Sun Dec 2 21:51:36 2007 UTC

… …
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", O_RDONLY, 0, sub {
10 my ($fh) = @_; 10 my $fh = shift
11 or die "/etc/passwd: $!";
11 ... 12 ...
12 }; 13 };
13 14
14 aio_unlink "/tmp/file", sub { }; 15 aio_unlink "/tmp/file", sub { };
15 16
… …
25 $req->cancel; # cancel request if still in queue 26 $req->cancel; # cancel request if still in queue
26 27
27 my $grp = aio_group sub { print "all stats done\n" }; 28 my $grp = aio_group sub { print "all stats done\n" };
28 add $grp aio_stat "..." for ...; 29 add $grp aio_stat "..." for ...;
29 30
30 # AnyEvent integration 31 # AnyEvent integration (EV, Event, Glib, Tk, urxvt, pureperl...)
31 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; 32 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
32 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); 33 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
34
35 # EV integration
36 my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
33 37
34 # Event integration 38 # Event integration
35 Event->io (fd => IO::AIO::poll_fileno, 39 Event->io (fd => IO::AIO::poll_fileno,
36 poll => 'r', 40 poll => 'r',
37 cb => \&IO::AIO::poll_cb); 41 cb => \&IO::AIO::poll_cb);
… …
50 54
51=head1 DESCRIPTION 55=head1 DESCRIPTION
52 56
53This module implements asynchronous I/O using whatever means your 57This module implements asynchronous I/O using whatever means your
54operating system supports. 58operating system supports.
59
60Asynchronous means that operations that can normally block your program
61(e.g. reading from disk) will be done asynchronously: the operation
62will still block, but you can do something else in the meantime. This
63is extremely useful for programs that need to stay interactive even
64when doing heavy I/O (GUI programs, high performance network servers
65etc.), but can also be used to easily do operations in parallel that are
66normally done sequentially, e.g. stat'ing many files, which is much faster
67on a RAID volume or over NFS when you do a number of stat operations
68concurrently.
69
70While most of this works on all types of file descriptors (for
71example sockets), using these functions on file descriptors that
72support nonblocking operation (again, sockets, pipes etc.) is very
73inefficient. Use an event loop for that (such as the L<Event|Event>
74module): IO::AIO will naturally fit into such an event loop itself.
55 75
56In this version, a number of threads are started that execute your 76In this version, a number of threads are started that execute your
57requests and signal their completion. You don't need thread support 77requests and signal their completion. You don't need thread support
58in perl, and the threads created by this module will not be visible 78in perl, and the threads created by this module will not be visible
59to perl. In the future, this module might make use of the native aio 79to perl. In the future, this module might make use of the native aio
60functions available on many operating systems. However, they are often 80functions available on many operating systems. However, they are often
61not well-supported or restricted (Linux doesn't allow them on normal 81not well-supported or restricted (GNU/Linux doesn't allow them on normal
62files currently, for example), and they would only support aio_read and 82files currently, for example), and they would only support aio_read and
63aio_write, so the remaining functionality would have to be implemented 83aio_write, so the remaining functionality would have to be implemented
64using threads anyway. 84using threads anyway.
65 85
66Although the module will work with in the presence of other (Perl-) 86Although the module will work in the presence of other (Perl-) threads,
67threads, it is currently not reentrant in any way, so use appropriate 87it is currently not reentrant in any way, so use appropriate locking
68locking yourself, always call C<poll_cb> from within the same thread, or 88yourself, always call C<poll_cb> from within the same thread, or never
69never call C<poll_cb> (or other C<aio_> functions) recursively. 89call C<poll_cb> (or other C<aio_> functions) recursively.
90
91=head2 EXAMPLE
92
93This is a simple example that uses the Event module and loads
94F</etc/passwd> asynchronously:
95
96 use Fcntl;
97 use Event;
98 use IO::AIO;
99
100 # register the IO::AIO callback with Event
101 Event->io (fd => IO::AIO::poll_fileno,
102 poll => 'r',
103 cb => \&IO::AIO::poll_cb);
104
105 # queue the request to open /etc/passwd
106 aio_open "/etc/passwd", O_RDONLY, 0, sub {
107 my $fh = shift
108 or die "error while opening: $!";
109
110 # stat'ing filehandles is generally non-blocking
111 my $size = -s $fh;
112
113 # queue a request to read the file
114 my $contents;
115 aio_read $fh, 0, $size, $contents, 0, sub {
116 $_[0] == $size
117 or die "short read: $!";
118
119 close $fh;
120
121 # file contents now in $contents
122 print $contents;
123
124 # exit event loop and program
125 Event::unloop;
126 };
127 };
128
129 # possibly queue up other requests, or open GUI windows,
130 # check for sockets etc. etc.
131
132 # process events as long as there are some:
133 Event::loop;
70 134
71=head1 REQUEST ANATOMY AND LIFETIME 135=head1 REQUEST ANATOMY AND LIFETIME
72 136
73Every C<aio_*> function creates a request. which is a C data structure not 137Every C<aio_*> function creates a request. which is a C data structure not
74directly visible to Perl. 138directly visible to Perl.
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116Request has reached the end of its lifetime and holds no resources anymore 180Request has reached the end of its lifetime and holds no resources anymore
117(except possibly for the Perl object, but its connection to the actual 181(except possibly for the Perl object, but its connection to the actual
118aio request is severed and calling its methods will either do nothing or 182aio request is severed and calling its methods will either do nothing or
119result in a runtime error). 183result in a runtime error).
120 184
185=back
186
121=cut 187=cut
122 188
123package IO::AIO; 189package IO::AIO;
190
191use Carp ();
124 192
125no warnings; 193no warnings;
126use strict 'vars'; 194use strict 'vars';
127 195
128use base 'Exporter'; 196use base 'Exporter';
129 197
130BEGIN { 198BEGIN {
131 our $VERSION = '2.0'; 199 our $VERSION = '2.6';
132 200
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 201 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
134 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 202 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir
135 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move 203 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
136 aio_group aio_nop); 204 aio_fdatasync aio_pathsync aio_readahead
205 aio_rename aio_link aio_move aio_copy aio_group
206 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
207 aio_chmod aio_utime aio_truncate);
208
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 209 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 210 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel nreqs nready npending); 211 min_parallel max_parallel max_idle
212 nreqs nready npending nthreads
213 max_poll_time max_poll_reqs);
140 214
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 215 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 216
143 require XSLoader; 217 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 218 XSLoader::load ("IO::AIO", $VERSION);
145} 219}
146 220
147=head1 FUNCTIONS 221=head1 FUNCTIONS
148 222
149=head2 AIO FUNCTIONS 223=head2 AIO REQUEST FUNCTIONS
150 224
151All the C<aio_*> calls are more or less thin wrappers around the syscall 225All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 226with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 227and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 228which must be a code reference. This code reference will get called with
… …
157syscall has been executed asynchronously. 231syscall has been executed asynchronously.
158 232
159All functions expecting a filehandle keep a copy of the filehandle 233All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 234internally until the request has finished.
161 235
162All requests return objects of type L<IO::AIO::REQ> that allow further 236All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 237further manipulation of those requests while they are in-flight.
164 238
165The pathnames you pass to these routines I<must> be absolute and 239The pathnames you pass to these routines I<must> be absolute and
166encoded in byte form. The reason for the former is that at the time the 240encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 241request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 242changed. Alternatively, you can make sure that you never change the
169current working directory. 243current working directory anywhere in the program and then use relative
244paths.
170 245
171To encode pathnames to byte form, either make sure you either: a) 246To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 247in filenames you got from outside (command line, readdir etc.) without
173etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode 248tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174your pathnames to the locale (or other) encoding in effect in the user 249your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 250environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 251use something else to ensure your scalar has the correct contents.
252
253This works, btw. independent of the internal UTF-8 bit, which IO::AIO
254handles correctly wether it is set or not.
177 255
178=over 4 256=over 4
179 257
180=item $prev_pri = aioreq_pri [$pri] 258=item $prev_pri = aioreq_pri [$pri]
181 259
… …
201 aio_read $_[0], ..., sub { 279 aio_read $_[0], ..., sub {
202 ... 280 ...
203 }; 281 };
204 }; 282 };
205 283
284
206=item aioreq_nice $pri_adjust 285=item aioreq_nice $pri_adjust
207 286
208Similar to C<aioreq_pri>, but subtracts the given value from the current 287Similar to C<aioreq_pri>, but subtracts the given value from the current
209priority, so effects are cumulative. 288priority, so the effect is cumulative.
289
210 290
211=item aio_open $pathname, $flags, $mode, $callback->($fh) 291=item aio_open $pathname, $flags, $mode, $callback->($fh)
212 292
213Asynchronously open or create a file and call the callback with a newly 293Asynchronously open or create a file and call the callback with a newly
214created filehandle for the file. 294created filehandle for the file.
… …
220list. They are the same as used by C<sysopen>. 300list. They are the same as used by C<sysopen>.
221 301
222Likewise, C<$mode> specifies the mode of the newly created file, if it 302Likewise, C<$mode> specifies the mode of the newly created file, if it
223didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, 303didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
224except that it is mandatory (i.e. use C<0> if you don't create new files, 304except that it is mandatory (i.e. use C<0> if you don't create new files,
225and C<0666> or C<0777> if you do). 305and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
306by the umask in effect then the request is being executed, so better never
307change the umask.
226 308
227Example: 309Example:
228 310
229 aio_open "/etc/passwd", O_RDONLY, 0, sub { 311 aio_open "/etc/passwd", O_RDONLY, 0, sub {
230 if ($_[0]) { 312 if ($_[0]) {
… …
233 } else { 315 } else {
234 die "open failed: $!\n"; 316 die "open failed: $!\n";
235 } 317 }
236 }; 318 };
237 319
320
238=item aio_close $fh, $callback->($status) 321=item aio_close $fh, $callback->($status)
239 322
240Asynchronously close a file and call the callback with the result 323Asynchronously close a file and call the callback with the result
241code. I<WARNING:> although accepted, you should not pass in a perl 324code.
242filehandle here, as perl will likely close the file descriptor another
243time when the filehandle is destroyed. Normally, you can safely call perls
244C<close> or just let filehandles go out of scope.
245 325
246This is supposed to be a bug in the API, so that might change. It's 326Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
247therefore best to avoid this function. 327closing the file descriptor associated with the filehandle itself. Here is
328what aio_close will try:
329
330 1. dup()licate the fd
331 2. asynchronously close() the duplicated fd
332 3. dup()licate the fd once more
333 4. let perl close() the filehandle
334 5. asynchronously close the duplicated fd
335
336The idea is that the first close() flushes stuff to disk that closing an
337fd will flush, so when perl closes the fd, nothing much will need to be
338flushed. The second async. close() will then flush stuff to disk that
339closing the last fd to the file will flush.
340
341Just FYI, SuSv3 has this to say on close:
342
343 All outstanding record locks owned by the process on the file
344 associated with the file descriptor shall be removed.
345
346 If fildes refers to a socket, close() shall cause the socket to be
347 destroyed. ... close() shall block for up to the current linger
348 interval until all data is transmitted.
349 [this actually sounds like a specification bug, but who knows]
350
351And at least Linux additionally actually flushes stuff on every close,
352even when the file itself is still open.
353
354Sounds enourmously inefficient and complicated? Yes... please show me how
355to nuke perl's fd out of existence...
356
357=cut
358
359sub aio_close($;$) {
360 aio_block {
361 my ($fh, $cb) = @_;
362
363 my $pri = aioreq_pri;
364 my $grp = aio_group $cb;
365
366 my $fd = fileno $fh;
367
368 defined $fd or Carp::croak "aio_close called with fd-less filehandle";
369
370 # if the dups fail we will simply get EBADF
371 my $fd2 = _dup $fd;
372 aioreq_pri $pri;
373 add $grp _aio_close $fd2, sub {
374 my $fd2 = _dup $fd;
375 close $fh;
376 aioreq_pri $pri;
377 add $grp _aio_close $fd2, sub {
378 $grp->result ($_[0]);
379 };
380 };
381
382 $grp
383 }
384}
385
248 386
249=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 387=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250 388
251=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 389=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252 390
253Reads or writes C<length> bytes from the specified C<fh> and C<offset> 391Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
254into the scalar given by C<data> and offset C<dataoffset> and calls the 392into the scalar given by C<$data> and offset C<$dataoffset> and calls the
255callback without the actual number of bytes read (or -1 on error, just 393callback without the actual number of bytes read (or -1 on error, just
256like the syscall). 394like the syscall).
257 395
396If C<$offset> is undefined, then the current file descriptor offset will
397be used (and updated), otherwise the file descriptor offset will not be
398changed by these calls.
399
400If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
401
402If C<$dataoffset> is less than zero, it will be counted from the end of
403C<$data>.
404
258The C<$data> scalar I<MUST NOT> be modified in any way while the request 405The C<$data> scalar I<MUST NOT> be modified in any way while the request
259is outstanding. Modifying it can result in segfaults or WW3 (if the 406is outstanding. Modifying it can result in segfaults or World War III (if
260necessary/optional hardware is installed). 407the necessary/optional hardware is installed).
261 408
262Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 409Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263offset C<0> within the scalar: 410offset C<0> within the scalar:
264 411
265 aio_read $fh, 7, 15, $buffer, 0, sub { 412 aio_read $fh, 7, 15, $buffer, 0, sub {
266 $_[0] > 0 or die "read error: $!"; 413 $_[0] > 0 or die "read error: $!";
267 print "read $_[0] bytes: <$buffer>\n"; 414 print "read $_[0] bytes: <$buffer>\n";
268 }; 415 };
269 416
270=item aio_move $srcpath, $dstpath, $callback->($status)
271
272Try to move the I<file> (directories not supported as either source or
273destination) from C<$srcpath> to C<$dstpath> and call the callback with
274the C<0> (error) or C<-1> ok.
275
276This is a composite request that tries to rename(2) the file first. If
277rename files with C<EXDEV>, it creates the destination file with mode 0200
278and copies the contents of the source file into it using C<aio_sendfile>,
279followed by restoring atime, mtime, access mode and uid/gid, in that
280order, and unlinking the C<$srcpath>.
281
282If an error occurs, the partial destination file will be unlinked, if
283possible, except when setting atime, mtime, access mode and uid/gid, where
284errors are being ignored.
285
286=cut
287
288sub aio_move($$$) {
289 my ($src, $dst, $cb) = @_;
290
291 my $pri = aioreq_pri;
292 my $grp = aio_group $cb;
293
294 aioreq_pri $pri;
295 add $grp aio_rename $src, $dst, sub {
296 if ($_[0] && $! == EXDEV) {
297 aioreq_pri $pri;
298 add $grp aio_open $src, O_RDONLY, 0, sub {
299 if (my $src_fh = $_[0]) {
300 my @stat = stat $src_fh;
301
302 aioreq_pri $pri;
303 add $grp aio_open $dst, O_WRONLY, 0200, sub {
304 if (my $dst_fh = $_[0]) {
305 aioreq_pri $pri;
306 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
307 close $src_fh;
308
309 if ($_[0] == $stat[7]) {
310 utime $stat[8], $stat[9], $dst;
311 chmod $stat[2] & 07777, $dst_fh;
312 chown $stat[4], $stat[5], $dst_fh;
313 close $dst_fh;
314
315 aioreq_pri $pri;
316 add $grp aio_unlink $src, sub {
317 $grp->result ($_[0]);
318 };
319 } else {
320 my $errno = $!;
321 aioreq_pri $pri;
322 add $grp aio_unlink $dst, sub {
323 $! = $errno;
324 $grp->result (-1);
325 };
326 }
327 };
328 } else {
329 $grp->result (-1);
330 }
331 },
332
333 } else {
334 $grp->result (-1);
335 }
336 };
337 } else {
338 $grp->result ($_[0]);
339 }
340 };
341
342 $grp
343}
344 417
345=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 418=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
346 419
347Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 420Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
348reading at byte offset C<$in_offset>, and starts writing at the current 421reading at byte offset C<$in_offset>, and starts writing at the current
… …
362C<$in_fh> than are written, and there is no way to find out how many 435C<$in_fh> than are written, and there is no way to find out how many
363bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 436bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
364provides the number of bytes written to C<$out_fh>. Only if the result 437provides the number of bytes written to C<$out_fh>. Only if the result
365value equals C<$length> one can assume that C<$length> bytes have been 438value equals C<$length> one can assume that C<$length> bytes have been
366read. 439read.
440
367 441
368=item aio_readahead $fh,$offset,$length, $callback->($retval) 442=item aio_readahead $fh,$offset,$length, $callback->($retval)
369 443
370C<aio_readahead> populates the page cache with data from a file so that 444C<aio_readahead> populates the page cache with data from a file so that
371subsequent reads from that file will not block on disk I/O. The C<$offset> 445subsequent reads from that file will not block on disk I/O. The C<$offset>
… …
377file. The current file offset of the file is left unchanged. 451file. The current file offset of the file is left unchanged.
378 452
379If that syscall doesn't exist (likely if your OS isn't Linux) it will be 453If that syscall doesn't exist (likely if your OS isn't Linux) it will be
380emulated by simply reading the data, which would have a similar effect. 454emulated by simply reading the data, which would have a similar effect.
381 455
456
382=item aio_stat $fh_or_path, $callback->($status) 457=item aio_stat $fh_or_path, $callback->($status)
383 458
384=item aio_lstat $fh, $callback->($status) 459=item aio_lstat $fh, $callback->($status)
385 460
386Works like perl's C<stat> or C<lstat> in void context. The callback will 461Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
399 aio_stat "/etc/passwd", sub { 474 aio_stat "/etc/passwd", sub {
400 $_[0] and die "stat failed: $!"; 475 $_[0] and die "stat failed: $!";
401 print "size is ", -s _, "\n"; 476 print "size is ", -s _, "\n";
402 }; 477 };
403 478
479
480=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
481
482Works like perl's C<utime> function (including the special case of $atime
483and $mtime being undef). Fractional times are supported if the underlying
484syscalls support them.
485
486When called with a pathname, uses utimes(2) if available, otherwise
487utime(2). If called on a file descriptor, uses futimes(2) if available,
488otherwise returns ENOSYS, so this is not portable.
489
490Examples:
491
492 # set atime and mtime to current time (basically touch(1)):
493 aio_utime "path", undef, undef;
494 # set atime to current time and mtime to beginning of the epoch:
495 aio_utime "path", time, undef; # undef==0
496
497
498=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
499
500Works like perl's C<chown> function, except that C<undef> for either $uid
501or $gid is being interpreted as "do not change" (but -1 can also be used).
502
503Examples:
504
505 # same as "chown root path" in the shell:
506 aio_chown "path", 0, -1;
507 # same as above:
508 aio_chown "path", 0, undef;
509
510
511=item aio_truncate $fh_or_path, $offset, $callback->($status)
512
513Works like truncate(2) or ftruncate(2).
514
515
516=item aio_chmod $fh_or_path, $mode, $callback->($status)
517
518Works like perl's C<chmod> function.
519
520
404=item aio_unlink $pathname, $callback->($status) 521=item aio_unlink $pathname, $callback->($status)
405 522
406Asynchronously unlink (delete) a file and call the callback with the 523Asynchronously unlink (delete) a file and call the callback with the
407result code. 524result code.
408 525
526
527=item aio_mknod $path, $mode, $dev, $callback->($status)
528
529[EXPERIMENTAL]
530
531Asynchronously create a device node (or fifo). See mknod(2).
532
533The only (POSIX-) portable way of calling this function is:
534
535 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
536
537
409=item aio_link $srcpath, $dstpath, $callback->($status) 538=item aio_link $srcpath, $dstpath, $callback->($status)
410 539
411Asynchronously create a new link to the existing object at C<$srcpath> at 540Asynchronously create a new link to the existing object at C<$srcpath> at
412the path C<$dstpath> and call the callback with the result code. 541the path C<$dstpath> and call the callback with the result code.
413 542
543
414=item aio_symlink $srcpath, $dstpath, $callback->($status) 544=item aio_symlink $srcpath, $dstpath, $callback->($status)
415 545
416Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 546Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
417the path C<$dstpath> and call the callback with the result code. 547the path C<$dstpath> and call the callback with the result code.
418 548
549
550=item aio_readlink $path, $callback->($link)
551
552Asynchronously read the symlink specified by C<$path> and pass it to
553the callback. If an error occurs, nothing or undef gets passed to the
554callback.
555
556
419=item aio_rename $srcpath, $dstpath, $callback->($status) 557=item aio_rename $srcpath, $dstpath, $callback->($status)
420 558
421Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 559Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422rename(2) and call the callback with the result code. 560rename(2) and call the callback with the result code.
423 561
562
563=item aio_mkdir $pathname, $mode, $callback->($status)
564
565Asynchronously mkdir (create) a directory and call the callback with
566the result code. C<$mode> will be modified by the umask at the time the
567request is executed, so do not change your umask.
568
569
424=item aio_rmdir $pathname, $callback->($status) 570=item aio_rmdir $pathname, $callback->($status)
425 571
426Asynchronously rmdir (delete) a directory and call the callback with the 572Asynchronously rmdir (delete) a directory and call the callback with the
427result code. 573result code.
574
428 575
429=item aio_readdir $pathname, $callback->($entries) 576=item aio_readdir $pathname, $callback->($entries)
430 577
431Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 578Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
432directory (i.e. opendir + readdir + closedir). The entries will not be 579directory (i.e. opendir + readdir + closedir). The entries will not be
433sorted, and will B<NOT> include the C<.> and C<..> entries. 580sorted, and will B<NOT> include the C<.> and C<..> entries.
434 581
435The callback a single argument which is either C<undef> or an array-ref 582The callback a single argument which is either C<undef> or an array-ref
436with the filenames. 583with the filenames.
584
585
586=item aio_load $path, $data, $callback->($status)
587
588This is a composite request that tries to fully load the given file into
589memory. Status is the same as with aio_read.
590
591=cut
592
593sub aio_load($$;$) {
594 aio_block {
595 my ($path, undef, $cb) = @_;
596 my $data = \$_[1];
597
598 my $pri = aioreq_pri;
599 my $grp = aio_group $cb;
600
601 aioreq_pri $pri;
602 add $grp aio_open $path, O_RDONLY, 0, sub {
603 my $fh = shift
604 or return $grp->result (-1);
605
606 aioreq_pri $pri;
607 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
608 $grp->result ($_[0]);
609 };
610 };
611
612 $grp
613 }
614}
615
616=item aio_copy $srcpath, $dstpath, $callback->($status)
617
618Try to copy the I<file> (directories not supported as either source or
619destination) from C<$srcpath> to C<$dstpath> and call the callback with
620the C<0> (error) or C<-1> ok.
621
622This is a composite request that it creates the destination file with
623mode 0200 and copies the contents of the source file into it using
624C<aio_sendfile>, followed by restoring atime, mtime, access mode and
625uid/gid, in that order.
626
627If an error occurs, the partial destination file will be unlinked, if
628possible, except when setting atime, mtime, access mode and uid/gid, where
629errors are being ignored.
630
631=cut
632
633sub aio_copy($$;$) {
634 aio_block {
635 my ($src, $dst, $cb) = @_;
636
637 my $pri = aioreq_pri;
638 my $grp = aio_group $cb;
639
640 aioreq_pri $pri;
641 add $grp aio_open $src, O_RDONLY, 0, sub {
642 if (my $src_fh = $_[0]) {
643 my @stat = stat $src_fh;
644
645 aioreq_pri $pri;
646 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
647 if (my $dst_fh = $_[0]) {
648 aioreq_pri $pri;
649 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
650 if ($_[0] == $stat[7]) {
651 $grp->result (0);
652 close $src_fh;
653
654 # those should not normally block. should. should.
655 utime $stat[8], $stat[9], $dst;
656 chmod $stat[2] & 07777, $dst_fh;
657 chown $stat[4], $stat[5], $dst_fh;
658
659 aioreq_pri $pri;
660 add $grp aio_close $dst_fh;
661 } else {
662 $grp->result (-1);
663 close $src_fh;
664 close $dst_fh;
665
666 aioreq $pri;
667 add $grp aio_unlink $dst;
668 }
669 };
670 } else {
671 $grp->result (-1);
672 }
673 },
674
675 } else {
676 $grp->result (-1);
677 }
678 };
679
680 $grp
681 }
682}
683
684=item aio_move $srcpath, $dstpath, $callback->($status)
685
686Try to move the I<file> (directories not supported as either source or
687destination) from C<$srcpath> to C<$dstpath> and call the callback with
688the C<0> (error) or C<-1> ok.
689
690This is a composite request that tries to rename(2) the file first. If
691rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
692that is successful, unlinking the C<$srcpath>.
693
694=cut
695
696sub aio_move($$;$) {
697 aio_block {
698 my ($src, $dst, $cb) = @_;
699
700 my $pri = aioreq_pri;
701 my $grp = aio_group $cb;
702
703 aioreq_pri $pri;
704 add $grp aio_rename $src, $dst, sub {
705 if ($_[0] && $! == EXDEV) {
706 aioreq_pri $pri;
707 add $grp aio_copy $src, $dst, sub {
708 $grp->result ($_[0]);
709
710 if (!$_[0]) {
711 aioreq_pri $pri;
712 add $grp aio_unlink $src;
713 }
714 };
715 } else {
716 $grp->result ($_[0]);
717 }
718 };
719
720 $grp
721 }
722}
437 723
438=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 724=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439 725
440Scans a directory (similar to C<aio_readdir>) but additionally tries to 726Scans a directory (similar to C<aio_readdir>) but additionally tries to
441efficiently separate the entries of directory C<$path> into two sets of 727efficiently separate the entries of directory C<$path> into two sets of
… …
487as those tend to return 0 or 1 as link counts, which disables the 773as those tend to return 0 or 1 as link counts, which disables the
488directory counting heuristic. 774directory counting heuristic.
489 775
490=cut 776=cut
491 777
492sub aio_scandir($$$) { 778sub aio_scandir($$;$) {
779 aio_block {
493 my ($path, $maxreq, $cb) = @_; 780 my ($path, $maxreq, $cb) = @_;
494 781
495 my $pri = aioreq_pri; 782 my $pri = aioreq_pri;
496 783
497 my $grp = aio_group $cb; 784 my $grp = aio_group $cb;
498 785
499 $maxreq = 4 if $maxreq <= 0; 786 $maxreq = 4 if $maxreq <= 0;
500 787
501 # stat once 788 # stat once
502 aioreq_pri $pri;
503 add $grp aio_stat $path, sub {
504 return $grp->result () if $_[0];
505 my $now = time;
506 my $hash1 = join ":", (stat _)[0,1,3,7,9];
507
508 # read the directory entries
509 aioreq_pri $pri; 789 aioreq_pri $pri;
510 add $grp aio_readdir $path, sub { 790 add $grp aio_stat $path, sub {
511 my $entries = shift
512 or return $grp->result (); 791 return $grp->result () if $_[0];
792 my $now = time;
793 my $hash1 = join ":", (stat _)[0,1,3,7,9];
513 794
514 # stat the dir another time 795 # read the directory entries
515 aioreq_pri $pri; 796 aioreq_pri $pri;
797 add $grp aio_readdir $path, sub {
798 my $entries = shift
799 or return $grp->result ();
800
801 # stat the dir another time
802 aioreq_pri $pri;
516 add $grp aio_stat $path, sub { 803 add $grp aio_stat $path, sub {
517 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 804 my $hash2 = join ":", (stat _)[0,1,3,7,9];
518 805
519 my $ndirs; 806 my $ndirs;
520 807
521 # take the slow route if anything looks fishy 808 # take the slow route if anything looks fishy
522 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 809 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523 $ndirs = -1; 810 $ndirs = -1;
524 } else { 811 } else {
525 # if nlink == 2, we are finished 812 # if nlink == 2, we are finished
526 # on non-posix-fs's, we rely on nlink < 2 813 # on non-posix-fs's, we rely on nlink < 2
527 $ndirs = (stat _)[3] - 2 814 $ndirs = (stat _)[3] - 2
528 or return $grp->result ([], $entries); 815 or return $grp->result ([], $entries);
529 } 816 }
530 817
531 # sort into likely dirs and likely nondirs 818 # sort into likely dirs and likely nondirs
532 # dirs == files without ".", short entries first 819 # dirs == files without ".", short entries first
533 $entries = [map $_->[0], 820 $entries = [map $_->[0],
534 sort { $b->[1] cmp $a->[1] } 821 sort { $b->[1] cmp $a->[1] }
535 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 822 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
536 @$entries]; 823 @$entries];
537 824
538 my (@dirs, @nondirs); 825 my (@dirs, @nondirs);
539 826
540 my $statgrp = add $grp aio_group sub { 827 my $statgrp = add $grp aio_group sub {
541 $grp->result (\@dirs, \@nondirs); 828 $grp->result (\@dirs, \@nondirs);
542 }; 829 };
543 830
544 limit $statgrp $maxreq; 831 limit $statgrp $maxreq;
545 feed $statgrp sub { 832 feed $statgrp sub {
546 return unless @$entries; 833 return unless @$entries;
547 my $entry = pop @$entries; 834 my $entry = pop @$entries;
548 835
549 aioreq_pri $pri; 836 aioreq_pri $pri;
550 add $statgrp aio_stat "$path/$entry/.", sub { 837 add $statgrp aio_stat "$path/$entry/.", sub {
551 if ($_[0] < 0) { 838 if ($_[0] < 0) {
552 push @nondirs, $entry; 839 push @nondirs, $entry;
553 } else { 840 } else {
554 # need to check for real directory 841 # need to check for real directory
555 aioreq_pri $pri; 842 aioreq_pri $pri;
556 add $statgrp aio_lstat "$path/$entry", sub { 843 add $statgrp aio_lstat "$path/$entry", sub {
557 if (-d _) { 844 if (-d _) {
558 push @dirs, $entry; 845 push @dirs, $entry;
559 846
560 unless (--$ndirs) { 847 unless (--$ndirs) {
561 push @nondirs, @$entries; 848 push @nondirs, @$entries;
562 feed $statgrp; 849 feed $statgrp;
850 }
851 } else {
852 push @nondirs, $entry;
563 } 853 }
564 } else {
565 push @nondirs, $entry;
566 } 854 }
567 } 855 }
568 } 856 };
569 }; 857 };
570 }; 858 };
571 }; 859 };
572 }; 860 };
861
862 $grp
573 }; 863 }
574
575 $grp
576} 864}
865
866=item aio_rmtree $path, $callback->($status)
867
868Delete a directory tree starting (and including) C<$path>, return the
869status of the final C<rmdir> only. This is a composite request that
870uses C<aio_scandir> to recurse into and rmdir directories, and unlink
871everything else.
872
873=cut
874
875sub aio_rmtree;
876sub aio_rmtree($;$) {
877 aio_block {
878 my ($path, $cb) = @_;
879
880 my $pri = aioreq_pri;
881 my $grp = aio_group $cb;
882
883 aioreq_pri $pri;
884 add $grp aio_scandir $path, 0, sub {
885 my ($dirs, $nondirs) = @_;
886
887 my $dirgrp = aio_group sub {
888 add $grp aio_rmdir $path, sub {
889 $grp->result ($_[0]);
890 };
891 };
892
893 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
894 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
895
896 add $grp $dirgrp;
897 };
898
899 $grp
900 }
901}
902
903=item aio_sync $callback->($status)
904
905Asynchronously call sync and call the callback when finished.
577 906
578=item aio_fsync $fh, $callback->($status) 907=item aio_fsync $fh, $callback->($status)
579 908
580Asynchronously call fsync on the given filehandle and call the callback 909Asynchronously call fsync on the given filehandle and call the callback
581with the fsync result code. 910with the fsync result code.
… …
585Asynchronously call fdatasync on the given filehandle and call the 914Asynchronously call fdatasync on the given filehandle and call the
586callback with the fdatasync result code. 915callback with the fdatasync result code.
587 916
588If this call isn't available because your OS lacks it or it couldn't be 917If this call isn't available because your OS lacks it or it couldn't be
589detected, it will be emulated by calling C<fsync> instead. 918detected, it will be emulated by calling C<fsync> instead.
919
920=item aio_pathsync $path, $callback->($status)
921
922This request tries to open, fsync and close the given path. This is a
923composite request intended tosync directories after directory operations
924(E.g. rename). This might not work on all operating systems or have any
925specific effect, but usually it makes sure that directory changes get
926written to disc. It works for anything that can be opened for read-only,
927not just directories.
928
929Passes C<0> when everything went ok, and C<-1> on error.
930
931=cut
932
933sub aio_pathsync($;$) {
934 aio_block {
935 my ($path, $cb) = @_;
936
937 my $pri = aioreq_pri;
938 my $grp = aio_group $cb;
939
940 aioreq_pri $pri;
941 add $grp aio_open $path, O_RDONLY, 0, sub {
942 my ($fh) = @_;
943 if ($fh) {
944 aioreq_pri $pri;
945 add $grp aio_fsync $fh, sub {
946 $grp->result ($_[0]);
947
948 aioreq_pri $pri;
949 add $grp aio_close $fh;
950 };
951 } else {
952 $grp->result (-1);
953 }
954 };
955
956 $grp
957 }
958}
590 959
591=item aio_group $callback->(...) 960=item aio_group $callback->(...)
592 961
593This is a very special aio request: Instead of doing something, it is a 962This is a very special aio request: Instead of doing something, it is a
594container for other aio requests, which is useful if you want to bundle 963container for other aio requests, which is useful if you want to bundle
… …
731itself. Useful when you queued a lot of events but got a result early. 1100itself. Useful when you queued a lot of events but got a result early.
732 1101
733=item $grp->result (...) 1102=item $grp->result (...)
734 1103
735Set the result value(s) that will be passed to the group callback when all 1104Set the result value(s) that will be passed to the group callback when all
736subrequests have finished and set thre groups errno to the current value 1105subrequests have finished and set the groups errno to the current value
737of errno (just like calling C<errno> without an error number). By default, 1106of errno (just like calling C<errno> without an error number). By default,
738no argument will be passed and errno is zero. 1107no argument will be passed and errno is zero.
739 1108
740=item $grp->errno ([$errno]) 1109=item $grp->errno ([$errno])
741 1110
… …
794 1163
795=back 1164=back
796 1165
797=head2 SUPPORT FUNCTIONS 1166=head2 SUPPORT FUNCTIONS
798 1167
1168=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1169
799=over 4 1170=over 4
800 1171
801=item $fileno = IO::AIO::poll_fileno 1172=item $fileno = IO::AIO::poll_fileno
802 1173
803Return the I<request result pipe file descriptor>. This filehandle must be 1174Return the I<request result pipe file descriptor>. This filehandle must be
… …
807 1178
808See C<poll_cb> for an example. 1179See C<poll_cb> for an example.
809 1180
810=item IO::AIO::poll_cb 1181=item IO::AIO::poll_cb
811 1182
812Process all outstanding events on the result pipe. You have to call this 1183Process some outstanding events on the result pipe. You have to call this
813regularly. Returns the number of events processed. Returns immediately 1184regularly. Returns the number of events processed. Returns immediately
814when no events are outstanding. 1185when no events are outstanding. The amount of events processed depends on
1186the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
815 1187
816If not all requests were processed for whatever reason, the filehandle 1188If not all requests were processed for whatever reason, the filehandle
817will still be ready when C<poll_cb> returns. 1189will still be ready when C<poll_cb> returns.
818 1190
819Example: Install an Event watcher that automatically calls 1191Example: Install an Event watcher that automatically calls
… …
821 1193
822 Event->io (fd => IO::AIO::poll_fileno, 1194 Event->io (fd => IO::AIO::poll_fileno,
823 poll => 'r', async => 1, 1195 poll => 'r', async => 1,
824 cb => \&IO::AIO::poll_cb); 1196 cb => \&IO::AIO::poll_cb);
825 1197
826=item IO::AIO::poll_some $max_requests 1198=item IO::AIO::max_poll_reqs $nreqs
827 1199
828Similar to C<poll_cb>, but only processes up to C<$max_requests> requests 1200=item IO::AIO::max_poll_time $seconds
829at a time.
830 1201
831Useful if you want to ensure some level of interactiveness when perl is 1202These set the maximum number of requests (default C<0>, meaning infinity)
832not fast enough to process all requests in time. 1203that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1204the maximum amount of time (default C<0>, meaning infinity) spent in
1205C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1206of time C<poll_cb> is allowed to use).
1207
1208Setting C<max_poll_time> to a non-zero value creates an overhead of one
1209syscall per request processed, which is not normally a problem unless your
1210callbacks are really really fast or your OS is really really slow (I am
1211not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1212
1213Setting these is useful if you want to ensure some level of
1214interactiveness when perl is not fast enough to process all requests in
1215time.
1216
1217For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833 1218
834Example: Install an Event watcher that automatically calls 1219Example: Install an Event watcher that automatically calls
835IO::AIO::poll_some with low priority, to ensure that other parts of the 1220IO::AIO::poll_cb with low priority, to ensure that other parts of the
836program get the CPU sometimes even under high AIO load. 1221program get the CPU sometimes even under high AIO load.
837 1222
1223 # try not to spend much more than 0.1s in poll_cb
1224 IO::AIO::max_poll_time 0.1;
1225
1226 # use a low priority so other tasks have priority
838 Event->io (fd => IO::AIO::poll_fileno, 1227 Event->io (fd => IO::AIO::poll_fileno,
839 poll => 'r', nice => 1, 1228 poll => 'r', nice => 1,
840 cb => sub { IO::AIO::poll_some 256 }); 1229 cb => &IO::AIO::poll_cb);
841 1230
842=item IO::AIO::poll_wait 1231=item IO::AIO::poll_wait
843 1232
1233If there are any outstanding requests and none of them in the result
844Wait till the result filehandle becomes ready for reading (simply does a 1234phase, wait till the result filehandle becomes ready for reading (simply
845C<select> on the filehandle. This is useful if you want to synchronously wait 1235does a C<select> on the filehandle. This is useful if you want to
846for some requests to finish). 1236synchronously wait for some requests to finish).
847 1237
848See C<nreqs> for an example. 1238See C<nreqs> for an example.
849 1239
1240=item IO::AIO::poll
1241
1242Waits until some requests have been handled.
1243
1244Returns the number of requests processed, but is otherwise strictly
1245equivalent to:
1246
1247 IO::AIO::poll_wait, IO::AIO::poll_cb
1248
850=item IO::AIO::nreqs 1249=item IO::AIO::flush
851 1250
852Returns the number of requests currently in the ready, execute or pending 1251Wait till all outstanding AIO requests have been handled.
853states (i.e. for which their callback has not been invoked yet).
854 1252
855Example: wait till there are no outstanding requests anymore: 1253Strictly equivalent to:
856 1254
857 IO::AIO::poll_wait, IO::AIO::poll_cb 1255 IO::AIO::poll_wait, IO::AIO::poll_cb
858 while IO::AIO::nreqs; 1256 while IO::AIO::nreqs;
859 1257
860=item IO::AIO::nready 1258=back
861 1259
862Returns the number of requests currently in the ready state (not yet 1260=head3 CONTROLLING THE NUMBER OF THREADS
863executed).
864 1261
865=item IO::AIO::npending 1262=over
866
867Returns the number of requests currently in the pending state (executed,
868but not yet processed by poll_cb).
869
870=item IO::AIO::flush
871
872Wait till all outstanding AIO requests have been handled.
873
874Strictly equivalent to:
875
876 IO::AIO::poll_wait, IO::AIO::poll_cb
877 while IO::AIO::nreqs;
878
879=item IO::AIO::poll
880
881Waits until some requests have been handled.
882
883Strictly equivalent to:
884
885 IO::AIO::poll_wait, IO::AIO::poll_cb
886 if IO::AIO::nreqs;
887 1263
888=item IO::AIO::min_parallel $nthreads 1264=item IO::AIO::min_parallel $nthreads
889 1265
890Set the minimum number of AIO threads to C<$nthreads>. The current 1266Set the minimum number of AIO threads to C<$nthreads>. The current
891default is C<8>, which means eight asynchronous operations can execute 1267default is C<8>, which means eight asynchronous operations can execute
892concurrently at any one time (the number of outstanding requests, 1268concurrently at any one time (the number of outstanding requests,
893however, is unlimited). 1269however, is unlimited).
894 1270
895IO::AIO starts threads only on demand, when an AIO request is queued and 1271IO::AIO starts threads only on demand, when an AIO request is queued and
896no free thread exists. 1272no free thread exists. Please note that queueing up a hundred requests can
1273create demand for a hundred threads, even if it turns out that everything
1274is in the cache and could have been processed faster by a single thread.
897 1275
898It is recommended to keep the number of threads relatively low, as some 1276It is recommended to keep the number of threads relatively low, as some
899Linux kernel versions will scale negatively with the number of threads 1277Linux kernel versions will scale negatively with the number of threads
900(higher parallelity => MUCH higher latency). With current Linux 2.6 1278(higher parallelity => MUCH higher latency). With current Linux 2.6
901versions, 4-32 threads should be fine. 1279versions, 4-32 threads should be fine.
… …
915This module automatically runs C<max_parallel 0> at program end, to ensure 1293This module automatically runs C<max_parallel 0> at program end, to ensure
916that all threads are killed and that there are no outstanding requests. 1294that all threads are killed and that there are no outstanding requests.
917 1295
918Under normal circumstances you don't need to call this function. 1296Under normal circumstances you don't need to call this function.
919 1297
1298=item IO::AIO::max_idle $nthreads
1299
1300Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1301threads that did not get a request to process within 10 seconds). That
1302means if a thread becomes idle while C<$nthreads> other threads are also
1303idle, it will free its resources and exit.
1304
1305This is useful when you allow a large number of threads (e.g. 100 or 1000)
1306to allow for extremely high load situations, but want to free resources
1307under normal circumstances (1000 threads can easily consume 30MB of RAM).
1308
1309The default is probably ok in most situations, especially if thread
1310creation is fast. If thread creation is very slow on your system you might
1311want to use larger values.
1312
920=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1313=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
921 1314
922This is a very bad function to use in interactive programs because it 1315This is a very bad function to use in interactive programs because it
923blocks, and a bad way to reduce concurrency because it is inexact: Better 1316blocks, and a bad way to reduce concurrency because it is inexact: Better
924use an C<aio_group> together with a feed callback. 1317use an C<aio_group> together with a feed callback.
925 1318
926Sets the maximum number of outstanding requests to C<$nreqs>. If you 1319Sets the maximum number of outstanding requests to C<$nreqs>. If you
927to queue up more than this number of requests, the next call to the 1320do queue up more than this number of requests, the next call to the
928C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>) 1321C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
929function will block until the limit is no longer exceeded. 1322function will block until the limit is no longer exceeded.
930 1323
931The default value is very large, so there is no practical limit on the 1324The default value is very large, so there is no practical limit on the
932number of outstanding requests. 1325number of outstanding requests.
… …
935C<max_oustsanding> is mainly useful in simple scripts (with low values) or 1328C<max_oustsanding> is mainly useful in simple scripts (with low values) or
936as a stop gap to shield against fatal memory overflow (with large values). 1329as a stop gap to shield against fatal memory overflow (with large values).
937 1330
938=back 1331=back
939 1332
1333=head3 STATISTICAL INFORMATION
1334
1335=over
1336
1337=item IO::AIO::nreqs
1338
1339Returns the number of requests currently in the ready, execute or pending
1340states (i.e. for which their callback has not been invoked yet).
1341
1342Example: wait till there are no outstanding requests anymore:
1343
1344 IO::AIO::poll_wait, IO::AIO::poll_cb
1345 while IO::AIO::nreqs;
1346
1347=item IO::AIO::nready
1348
1349Returns the number of requests currently in the ready state (not yet
1350executed).
1351
1352=item IO::AIO::npending
1353
1354Returns the number of requests currently in the pending state (executed,
1355but not yet processed by poll_cb).
1356
1357=back
1358
940=cut 1359=cut
941 1360
942# support function to convert a fd into a perl filehandle
943sub _fd2fh {
944 return undef if $_[0] < 0;
945
946 # try to generate nice filehandles
947 my $sym = "IO::AIO::fd#$_[0]";
948 local *$sym;
949
950 open *$sym, "+<&=$_[0]" # usually works under any unix
951 or open *$sym, "<&=$_[0]" # cygwin needs this
952 or open *$sym, ">&=$_[0]" # or this
953 or return undef;
954
955 *$sym
956}
957
958min_parallel 8; 1361min_parallel 8;
1362
1363END { flush }
959 1364
9601; 13651;
961 1366
962=head2 FORK BEHAVIOUR 1367=head2 FORK BEHAVIOUR
963 1368
… …
983bytes of memory. In addition, stat requests need a stat buffer (possibly 1388bytes of memory. In addition, stat requests need a stat buffer (possibly
984a few hundred bytes), readdir requires a result buffer and so on. Perl 1389a few hundred bytes), readdir requires a result buffer and so on. Perl
985scalars and other data passed into aio requests will also be locked and 1390scalars and other data passed into aio requests will also be locked and
986will consume memory till the request has entered the done state. 1391will consume memory till the request has entered the done state.
987 1392
988This is now awfully much, so queuing lots of requests is not usually a 1393This is not awfully much, so queuing lots of requests is not usually a
989problem. 1394problem.
990 1395
991Per-thread usage: 1396Per-thread usage:
992 1397
993In the execution phase, some aio requests require more memory for 1398In the execution phase, some aio requests require more memory for

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