ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/IO-AIO/AIO.pm
(Generate patch)

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.76 by root, Wed Oct 25 08:20:14 2006 UTC vs.
Revision 1.119 by root, Sun Dec 2 20:54:33 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.
… …
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 aio_stat
134 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 202 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
135 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move 203 aio_readlink aio_sync aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
136 aio_group aio_nop); 204 aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
205 aio_chown aio_chmod aio_utime aio_truncate);
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 206 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 207 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel max_outstanding nreqs); 208 min_parallel max_parallel max_idle
209 nreqs nready npending nthreads
210 max_poll_time max_poll_reqs);
140 211
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 212 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 213
143 require XSLoader; 214 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 215 XSLoader::load ("IO::AIO", $VERSION);
145} 216}
146 217
147=head1 FUNCTIONS 218=head1 FUNCTIONS
148 219
149=head2 AIO FUNCTIONS 220=head2 AIO REQUEST FUNCTIONS
150 221
151All the C<aio_*> calls are more or less thin wrappers around the syscall 222All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 223with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 224and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 225which must be a code reference. This code reference will get called with
… …
157syscall has been executed asynchronously. 228syscall has been executed asynchronously.
158 229
159All functions expecting a filehandle keep a copy of the filehandle 230All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 231internally until the request has finished.
161 232
162All requests return objects of type L<IO::AIO::REQ> that allow further 233All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 234further manipulation of those requests while they are in-flight.
164 235
165The pathnames you pass to these routines I<must> be absolute and 236The 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 237encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 238request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 239changed. Alternatively, you can make sure that you never change the
169current working directory. 240current working directory anywhere in the program and then use relative
241paths.
170 242
171To encode pathnames to byte form, either make sure you either: a) 243To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 244in 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 245tinkering, 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 246your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 247environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 248use something else to ensure your scalar has the correct contents.
249
250This works, btw. independent of the internal UTF-8 bit, which IO::AIO
251handles correctly wether it is set or not.
177 252
178=over 4 253=over 4
179 254
180=item aioreq_pri $pri 255=item $prev_pri = aioreq_pri [$pri]
181 256
182Sets the priority for the next aio request. The default priority 257Returns the priority value that would be used for the next request and, if
258C<$pri> is given, sets the priority for the next aio request.
259
183is C<0>, the minimum and maximum priorities are C<-4> and C<4>, 260The default priority is C<0>, the minimum and maximum priorities are C<-4>
184respectively. Requests with higher priority will be serviced first. 261and C<4>, respectively. Requests with higher priority will be serviced
262first.
185 263
186The priority will be reset to C<0> after each call to one of the C<aio_> 264The priority will be reset to C<0> after each call to one of the C<aio_*>
187functions. 265functions.
188 266
189Example: open a file with low priority, then read something from it with 267Example: open a file with low priority, then read something from it with
190higher priority so the read request is serviced before other low priority 268higher priority so the read request is serviced before other low priority
191open requests (potentially spamming the cache): 269open requests (potentially spamming the cache):
… …
198 aio_read $_[0], ..., sub { 276 aio_read $_[0], ..., sub {
199 ... 277 ...
200 }; 278 };
201 }; 279 };
202 280
281
203=item aioreq_nice $pri_adjust 282=item aioreq_nice $pri_adjust
204 283
205Similar to C<aioreq_pri>, but subtracts the given value from the current 284Similar to C<aioreq_pri>, but subtracts the given value from the current
206priority, so effects are cumulative. 285priority, so the effect is cumulative.
286
207 287
208=item aio_open $pathname, $flags, $mode, $callback->($fh) 288=item aio_open $pathname, $flags, $mode, $callback->($fh)
209 289
210Asynchronously open or create a file and call the callback with a newly 290Asynchronously open or create a file and call the callback with a newly
211created filehandle for the file. 291created filehandle for the file.
… …
217list. They are the same as used by C<sysopen>. 297list. They are the same as used by C<sysopen>.
218 298
219Likewise, C<$mode> specifies the mode of the newly created file, if it 299Likewise, C<$mode> specifies the mode of the newly created file, if it
220didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, 300didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
221except that it is mandatory (i.e. use C<0> if you don't create new files, 301except that it is mandatory (i.e. use C<0> if you don't create new files,
222and C<0666> or C<0777> if you do). 302and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
303by the umask in effect then the request is being executed, so better never
304change the umask.
223 305
224Example: 306Example:
225 307
226 aio_open "/etc/passwd", O_RDONLY, 0, sub { 308 aio_open "/etc/passwd", O_RDONLY, 0, sub {
227 if ($_[0]) { 309 if ($_[0]) {
… …
230 } else { 312 } else {
231 die "open failed: $!\n"; 313 die "open failed: $!\n";
232 } 314 }
233 }; 315 };
234 316
317
235=item aio_close $fh, $callback->($status) 318=item aio_close $fh, $callback->($status)
236 319
237Asynchronously close a file and call the callback with the result 320Asynchronously close a file and call the callback with the result
238code. I<WARNING:> although accepted, you should not pass in a perl 321code.
239filehandle here, as perl will likely close the file descriptor another
240time when the filehandle is destroyed. Normally, you can safely call perls
241C<close> or just let filehandles go out of scope.
242 322
243This is supposed to be a bug in the API, so that might change. It's 323Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
244therefore best to avoid this function. 324closing the file descriptor associated with the filehandle itself. Here is
325what aio_close will try:
326
327 1. dup()licate the fd
328 2. asynchronously close() the duplicated fd
329 3. dup()licate the fd once more
330 4. let perl close() the filehandle
331 5. asynchronously close the duplicated fd
332
333The idea is that the first close() flushes stuff to disk that closing an
334fd will flush, so when perl closes the fd, nothing much will need to be
335flushed. The second async. close() will then flush stuff to disk that
336closing the last fd to the file will flush.
337
338Just FYI, SuSv3 has this to say on close:
339
340 All outstanding record locks owned by the process on the file
341 associated with the file descriptor shall be removed.
342
343 If fildes refers to a socket, close() shall cause the socket to be
344 destroyed. ... close() shall block for up to the current linger
345 interval until all data is transmitted.
346 [this actually sounds like a specification bug, but who knows]
347
348And at least Linux additionally actually flushes stuff on every close,
349even when the file itself is still open.
350
351Sounds enourmously inefficient and complicated? Yes... please show me how
352to nuke perl's fd out of existence...
353
354=cut
355
356sub aio_close($;$) {
357 aio_block {
358 my ($fh, $cb) = @_;
359
360 my $pri = aioreq_pri;
361 my $grp = aio_group $cb;
362
363 my $fd = fileno $fh;
364
365 defined $fd or Carp::croak "aio_close called with fd-less filehandle";
366
367 # if the dups fail we will simply get EBADF
368 my $fd2 = _dup $fd;
369 aioreq_pri $pri;
370 add $grp _aio_close $fd2, sub {
371 my $fd2 = _dup $fd;
372 close $fh;
373 aioreq_pri $pri;
374 add $grp _aio_close $fd2, sub {
375 $grp->result ($_[0]);
376 };
377 };
378
379 $grp
380 }
381}
382
245 383
246=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 384=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
247 385
248=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 386=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
249 387
250Reads or writes C<length> bytes from the specified C<fh> and C<offset> 388Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
251into the scalar given by C<data> and offset C<dataoffset> and calls the 389into the scalar given by C<$data> and offset C<$dataoffset> and calls the
252callback without the actual number of bytes read (or -1 on error, just 390callback without the actual number of bytes read (or -1 on error, just
253like the syscall). 391like the syscall).
254 392
393If C<$offset> is undefined, then the current file descriptor offset will
394be used (and updated), otherwise the file descriptor offset will not be
395changed by these calls.
396
397If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
398
399If C<$dataoffset> is less than zero, it will be counted from the end of
400C<$data>.
401
255The C<$data> scalar I<MUST NOT> be modified in any way while the request 402The C<$data> scalar I<MUST NOT> be modified in any way while the request
256is outstanding. Modifying it can result in segfaults or WW3 (if the 403is outstanding. Modifying it can result in segfaults or World War III (if
257necessary/optional hardware is installed). 404the necessary/optional hardware is installed).
258 405
259Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 406Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
260offset C<0> within the scalar: 407offset C<0> within the scalar:
261 408
262 aio_read $fh, 7, 15, $buffer, 0, sub { 409 aio_read $fh, 7, 15, $buffer, 0, sub {
263 $_[0] > 0 or die "read error: $!"; 410 $_[0] > 0 or die "read error: $!";
264 print "read $_[0] bytes: <$buffer>\n"; 411 print "read $_[0] bytes: <$buffer>\n";
265 }; 412 };
266 413
267=item aio_move $srcpath, $dstpath, $callback->($status)
268
269Try to move the I<file> (directories not supported as either source or
270destination) from C<$srcpath> to C<$dstpath> and call the callback with
271the C<0> (error) or C<-1> ok.
272
273This is a composite request that tries to rename(2) the file first. If
274rename files with C<EXDEV>, it creates the destination file with mode 0200
275and copies the contents of the source file into it using C<aio_sendfile>,
276followed by restoring atime, mtime, access mode and uid/gid, in that
277order, and unlinking the C<$srcpath>.
278
279If an error occurs, the partial destination file will be unlinked, if
280possible, except when setting atime, mtime, access mode and uid/gid, where
281errors are being ignored.
282
283=cut
284
285sub aio_move($$$) {
286 my ($src, $dst, $cb) = @_;
287
288 my $grp = aio_group $cb;
289
290 add $grp aio_rename $src, $dst, sub {
291 if ($_[0] && $! == EXDEV) {
292 add $grp aio_open $src, O_RDONLY, 0, sub {
293 if (my $src_fh = $_[0]) {
294 my @stat = stat $src_fh;
295
296 add $grp aio_open $dst, O_WRONLY, 0200, sub {
297 if (my $dst_fh = $_[0]) {
298 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
299 close $src_fh;
300
301 if ($_[0] == $stat[7]) {
302 utime $stat[8], $stat[9], $dst;
303 chmod $stat[2] & 07777, $dst_fh;
304 chown $stat[4], $stat[5], $dst_fh;
305 close $dst_fh;
306
307 add $grp aio_unlink $src, sub {
308 $grp->result ($_[0]);
309 };
310 } else {
311 my $errno = $!;
312 add $grp aio_unlink $dst, sub {
313 $! = $errno;
314 $grp->result (-1);
315 };
316 }
317 };
318 } else {
319 $grp->result (-1);
320 }
321 },
322
323 } else {
324 $grp->result (-1);
325 }
326 };
327 } else {
328 $grp->result ($_[0]);
329 }
330 };
331
332 $grp
333}
334 414
335=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 415=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
336 416
337Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 417Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
338reading at byte offset C<$in_offset>, and starts writing at the current 418reading at byte offset C<$in_offset>, and starts writing at the current
… …
352C<$in_fh> than are written, and there is no way to find out how many 432C<$in_fh> than are written, and there is no way to find out how many
353bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 433bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
354provides the number of bytes written to C<$out_fh>. Only if the result 434provides the number of bytes written to C<$out_fh>. Only if the result
355value equals C<$length> one can assume that C<$length> bytes have been 435value equals C<$length> one can assume that C<$length> bytes have been
356read. 436read.
437
357 438
358=item aio_readahead $fh,$offset,$length, $callback->($retval) 439=item aio_readahead $fh,$offset,$length, $callback->($retval)
359 440
360C<aio_readahead> populates the page cache with data from a file so that 441C<aio_readahead> populates the page cache with data from a file so that
361subsequent reads from that file will not block on disk I/O. The C<$offset> 442subsequent reads from that file will not block on disk I/O. The C<$offset>
… …
367file. The current file offset of the file is left unchanged. 448file. The current file offset of the file is left unchanged.
368 449
369If that syscall doesn't exist (likely if your OS isn't Linux) it will be 450If that syscall doesn't exist (likely if your OS isn't Linux) it will be
370emulated by simply reading the data, which would have a similar effect. 451emulated by simply reading the data, which would have a similar effect.
371 452
453
372=item aio_stat $fh_or_path, $callback->($status) 454=item aio_stat $fh_or_path, $callback->($status)
373 455
374=item aio_lstat $fh, $callback->($status) 456=item aio_lstat $fh, $callback->($status)
375 457
376Works like perl's C<stat> or C<lstat> in void context. The callback will 458Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
389 aio_stat "/etc/passwd", sub { 471 aio_stat "/etc/passwd", sub {
390 $_[0] and die "stat failed: $!"; 472 $_[0] and die "stat failed: $!";
391 print "size is ", -s _, "\n"; 473 print "size is ", -s _, "\n";
392 }; 474 };
393 475
476
477=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
478
479Works like perl's C<utime> function (including the special case of $atime
480and $mtime being undef). Fractional times are supported if the underlying
481syscalls support them.
482
483When called with a pathname, uses utimes(2) if available, otherwise
484utime(2). If called on a file descriptor, uses futimes(2) if available,
485otherwise returns ENOSYS, so this is not portable.
486
487Examples:
488
489 # set atime and mtime to current time (basically touch(1)):
490 aio_utime "path", undef, undef;
491 # set atime to current time and mtime to beginning of the epoch:
492 aio_utime "path", time, undef; # undef==0
493
494
495=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
496
497Works like perl's C<chown> function, except that C<undef> for either $uid
498or $gid is being interpreted as "do not change" (but -1 can also be used).
499
500Examples:
501
502 # same as "chown root path" in the shell:
503 aio_chown "path", 0, -1;
504 # same as above:
505 aio_chown "path", 0, undef;
506
507
508=item aio_truncate $fh_or_path, $offset, $callback->($status)
509
510Works like truncate(2) or ftruncate(2).
511
512
513=item aio_chmod $fh_or_path, $mode, $callback->($status)
514
515Works like perl's C<chmod> function.
516
517
394=item aio_unlink $pathname, $callback->($status) 518=item aio_unlink $pathname, $callback->($status)
395 519
396Asynchronously unlink (delete) a file and call the callback with the 520Asynchronously unlink (delete) a file and call the callback with the
397result code. 521result code.
398 522
523
524=item aio_mknod $path, $mode, $dev, $callback->($status)
525
526[EXPERIMENTAL]
527
528Asynchronously create a device node (or fifo). See mknod(2).
529
530The only (POSIX-) portable way of calling this function is:
531
532 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
533
534
399=item aio_link $srcpath, $dstpath, $callback->($status) 535=item aio_link $srcpath, $dstpath, $callback->($status)
400 536
401Asynchronously create a new link to the existing object at C<$srcpath> at 537Asynchronously create a new link to the existing object at C<$srcpath> at
402the path C<$dstpath> and call the callback with the result code. 538the path C<$dstpath> and call the callback with the result code.
403 539
540
404=item aio_symlink $srcpath, $dstpath, $callback->($status) 541=item aio_symlink $srcpath, $dstpath, $callback->($status)
405 542
406Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 543Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
407the path C<$dstpath> and call the callback with the result code. 544the path C<$dstpath> and call the callback with the result code.
408 545
546
547=item aio_readlink $path, $callback->($link)
548
549Asynchronously read the symlink specified by C<$path> and pass it to
550the callback. If an error occurs, nothing or undef gets passed to the
551callback.
552
553
409=item aio_rename $srcpath, $dstpath, $callback->($status) 554=item aio_rename $srcpath, $dstpath, $callback->($status)
410 555
411Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 556Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
412rename(2) and call the callback with the result code. 557rename(2) and call the callback with the result code.
413 558
559
560=item aio_mkdir $pathname, $mode, $callback->($status)
561
562Asynchronously mkdir (create) a directory and call the callback with
563the result code. C<$mode> will be modified by the umask at the time the
564request is executed, so do not change your umask.
565
566
414=item aio_rmdir $pathname, $callback->($status) 567=item aio_rmdir $pathname, $callback->($status)
415 568
416Asynchronously rmdir (delete) a directory and call the callback with the 569Asynchronously rmdir (delete) a directory and call the callback with the
417result code. 570result code.
571
418 572
419=item aio_readdir $pathname, $callback->($entries) 573=item aio_readdir $pathname, $callback->($entries)
420 574
421Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 575Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
422directory (i.e. opendir + readdir + closedir). The entries will not be 576directory (i.e. opendir + readdir + closedir). The entries will not be
423sorted, and will B<NOT> include the C<.> and C<..> entries. 577sorted, and will B<NOT> include the C<.> and C<..> entries.
424 578
425The callback a single argument which is either C<undef> or an array-ref 579The callback a single argument which is either C<undef> or an array-ref
426with the filenames. 580with the filenames.
581
582
583=item aio_load $path, $data, $callback->($status)
584
585This is a composite request that tries to fully load the given file into
586memory. Status is the same as with aio_read.
587
588=cut
589
590sub aio_load($$;$) {
591 aio_block {
592 my ($path, undef, $cb) = @_;
593 my $data = \$_[1];
594
595 my $pri = aioreq_pri;
596 my $grp = aio_group $cb;
597
598 aioreq_pri $pri;
599 add $grp aio_open $path, O_RDONLY, 0, sub {
600 my $fh = shift
601 or return $grp->result (-1);
602
603 aioreq_pri $pri;
604 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
605 $grp->result ($_[0]);
606 };
607 };
608
609 $grp
610 }
611}
612
613=item aio_copy $srcpath, $dstpath, $callback->($status)
614
615Try to copy the I<file> (directories not supported as either source or
616destination) from C<$srcpath> to C<$dstpath> and call the callback with
617the C<0> (error) or C<-1> ok.
618
619This is a composite request that it creates the destination file with
620mode 0200 and copies the contents of the source file into it using
621C<aio_sendfile>, followed by restoring atime, mtime, access mode and
622uid/gid, in that order.
623
624If an error occurs, the partial destination file will be unlinked, if
625possible, except when setting atime, mtime, access mode and uid/gid, where
626errors are being ignored.
627
628=cut
629
630sub aio_copy($$;$) {
631 aio_block {
632 my ($src, $dst, $cb) = @_;
633
634 my $pri = aioreq_pri;
635 my $grp = aio_group $cb;
636
637 aioreq_pri $pri;
638 add $grp aio_open $src, O_RDONLY, 0, sub {
639 if (my $src_fh = $_[0]) {
640 my @stat = stat $src_fh;
641
642 aioreq_pri $pri;
643 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
644 if (my $dst_fh = $_[0]) {
645 aioreq_pri $pri;
646 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
647 if ($_[0] == $stat[7]) {
648 $grp->result (0);
649 close $src_fh;
650
651 # those should not normally block. should. should.
652 utime $stat[8], $stat[9], $dst;
653 chmod $stat[2] & 07777, $dst_fh;
654 chown $stat[4], $stat[5], $dst_fh;
655 close $dst_fh;
656 } else {
657 $grp->result (-1);
658 close $src_fh;
659 close $dst_fh;
660
661 aioreq $pri;
662 add $grp aio_unlink $dst;
663 }
664 };
665 } else {
666 $grp->result (-1);
667 }
668 },
669
670 } else {
671 $grp->result (-1);
672 }
673 };
674
675 $grp
676 }
677}
678
679=item aio_move $srcpath, $dstpath, $callback->($status)
680
681Try to move the I<file> (directories not supported as either source or
682destination) from C<$srcpath> to C<$dstpath> and call the callback with
683the C<0> (error) or C<-1> ok.
684
685This is a composite request that tries to rename(2) the file first. If
686rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
687that is successful, unlinking the C<$srcpath>.
688
689=cut
690
691sub aio_move($$;$) {
692 aio_block {
693 my ($src, $dst, $cb) = @_;
694
695 my $pri = aioreq_pri;
696 my $grp = aio_group $cb;
697
698 aioreq_pri $pri;
699 add $grp aio_rename $src, $dst, sub {
700 if ($_[0] && $! == EXDEV) {
701 aioreq_pri $pri;
702 add $grp aio_copy $src, $dst, sub {
703 $grp->result ($_[0]);
704
705 if (!$_[0]) {
706 aioreq_pri $pri;
707 add $grp aio_unlink $src;
708 }
709 };
710 } else {
711 $grp->result ($_[0]);
712 }
713 };
714
715 $grp
716 }
717}
427 718
428=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 719=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429 720
430Scans a directory (similar to C<aio_readdir>) but additionally tries to 721Scans a directory (similar to C<aio_readdir>) but additionally tries to
431efficiently separate the entries of directory C<$path> into two sets of 722efficiently separate the entries of directory C<$path> into two sets of
… …
433recurse into (everything else, including symlinks to directories). 724recurse into (everything else, including symlinks to directories).
434 725
435C<aio_scandir> is a composite request that creates of many sub requests_ 726C<aio_scandir> is a composite request that creates of many sub requests_
436C<$maxreq> specifies the maximum number of outstanding aio requests that 727C<$maxreq> specifies the maximum number of outstanding aio requests that
437this function generates. If it is C<< <= 0 >>, then a suitable default 728this function generates. If it is C<< <= 0 >>, then a suitable default
438will be chosen (currently 6). 729will be chosen (currently 4).
439 730
440On error, the callback is called without arguments, otherwise it receives 731On error, the callback is called without arguments, otherwise it receives
441two array-refs with path-relative entry names. 732two array-refs with path-relative entry names.
442 733
443Example: 734Example:
… …
477as those tend to return 0 or 1 as link counts, which disables the 768as those tend to return 0 or 1 as link counts, which disables the
478directory counting heuristic. 769directory counting heuristic.
479 770
480=cut 771=cut
481 772
482sub aio_scandir($$$) { 773sub aio_scandir($$;$) {
774 aio_block {
483 my ($path, $maxreq, $cb) = @_; 775 my ($path, $maxreq, $cb) = @_;
484 776
777 my $pri = aioreq_pri;
778
485 my $grp = aio_group $cb; 779 my $grp = aio_group $cb;
486 780
487 $maxreq = 6 if $maxreq <= 0; 781 $maxreq = 4 if $maxreq <= 0;
488 782
489 # stat once 783 # stat once
784 aioreq_pri $pri;
490 add $grp aio_stat $path, sub { 785 add $grp aio_stat $path, sub {
491 return $grp->result () if $_[0]; 786 return $grp->result () if $_[0];
492 my $now = time; 787 my $now = time;
493 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 788 my $hash1 = join ":", (stat _)[0,1,3,7,9];
494 789
495 # read the directory entries 790 # read the directory entries
791 aioreq_pri $pri;
496 add $grp aio_readdir $path, sub { 792 add $grp aio_readdir $path, sub {
497 my $entries = shift 793 my $entries = shift
498 or return $grp->result (); 794 or return $grp->result ();
499 795
500 # stat the dir another time 796 # stat the dir another time
797 aioreq_pri $pri;
501 add $grp aio_stat $path, sub { 798 add $grp aio_stat $path, sub {
502 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 799 my $hash2 = join ":", (stat _)[0,1,3,7,9];
503 800
504 my $ndirs; 801 my $ndirs;
505 802
506 # take the slow route if anything looks fishy 803 # take the slow route if anything looks fishy
507 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 804 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508 $ndirs = -1; 805 $ndirs = -1;
509 } else { 806 } else {
510 # if nlink == 2, we are finished 807 # if nlink == 2, we are finished
511 # on non-posix-fs's, we rely on nlink < 2 808 # on non-posix-fs's, we rely on nlink < 2
512 $ndirs = (stat _)[3] - 2 809 $ndirs = (stat _)[3] - 2
513 or return $grp->result ([], $entries); 810 or return $grp->result ([], $entries);
514 } 811 }
515 812
516 # sort into likely dirs and likely nondirs 813 # sort into likely dirs and likely nondirs
517 # dirs == files without ".", short entries first 814 # dirs == files without ".", short entries first
518 $entries = [map $_->[0], 815 $entries = [map $_->[0],
519 sort { $b->[1] cmp $a->[1] } 816 sort { $b->[1] cmp $a->[1] }
520 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 817 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
521 @$entries]; 818 @$entries];
522 819
523 my (@dirs, @nondirs); 820 my (@dirs, @nondirs);
524 821
525 my $statgrp = add $grp aio_group sub { 822 my $statgrp = add $grp aio_group sub {
526 $grp->result (\@dirs, \@nondirs); 823 $grp->result (\@dirs, \@nondirs);
527 }; 824 };
528 825
529 limit $statgrp $maxreq; 826 limit $statgrp $maxreq;
530 feed $statgrp sub { 827 feed $statgrp sub {
531 return unless @$entries; 828 return unless @$entries;
532 my $entry = pop @$entries; 829 my $entry = pop @$entries;
533 830
831 aioreq_pri $pri;
534 add $statgrp aio_stat "$path/$entry/.", sub { 832 add $statgrp aio_stat "$path/$entry/.", sub {
535 if ($_[0] < 0) { 833 if ($_[0] < 0) {
536 push @nondirs, $entry; 834 push @nondirs, $entry;
537 } else { 835 } else {
538 # need to check for real directory 836 # need to check for real directory
837 aioreq_pri $pri;
539 add $statgrp aio_lstat "$path/$entry", sub { 838 add $statgrp aio_lstat "$path/$entry", sub {
540 if (-d _) { 839 if (-d _) {
541 push @dirs, $entry; 840 push @dirs, $entry;
542 841
543 unless (--$ndirs) { 842 unless (--$ndirs) {
544 push @nondirs, @$entries; 843 push @nondirs, @$entries;
545 feed $statgrp; 844 feed $statgrp;
845 }
846 } else {
847 push @nondirs, $entry;
546 } 848 }
547 } else {
548 push @nondirs, $entry;
549 } 849 }
550 } 850 }
551 } 851 };
552 }; 852 };
553 }; 853 };
554 }; 854 };
555 }; 855 };
856
857 $grp
556 }; 858 }
557
558 $grp
559} 859}
860
861=item aio_rmtree $path, $callback->($status)
862
863Delete a directory tree starting (and including) C<$path>, return the
864status of the final C<rmdir> only. This is a composite request that
865uses C<aio_scandir> to recurse into and rmdir directories, and unlink
866everything else.
867
868=cut
869
870sub aio_rmtree;
871sub aio_rmtree($;$) {
872 aio_block {
873 my ($path, $cb) = @_;
874
875 my $pri = aioreq_pri;
876 my $grp = aio_group $cb;
877
878 aioreq_pri $pri;
879 add $grp aio_scandir $path, 0, sub {
880 my ($dirs, $nondirs) = @_;
881
882 my $dirgrp = aio_group sub {
883 add $grp aio_rmdir $path, sub {
884 $grp->result ($_[0]);
885 };
886 };
887
888 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
889 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
890
891 add $grp $dirgrp;
892 };
893
894 $grp
895 }
896}
897
898=item aio_sync $callback->($status)
899
900Asynchronously call sync and call the callback when finished.
560 901
561=item aio_fsync $fh, $callback->($status) 902=item aio_fsync $fh, $callback->($status)
562 903
563Asynchronously call fsync on the given filehandle and call the callback 904Asynchronously call fsync on the given filehandle and call the callback
564with the fsync result code. 905with the fsync result code.
… …
682=item * They can also can also be added to other IO::AIO::GRP objects. 1023=item * They can also can also be added to other IO::AIO::GRP objects.
683 1024
684=item * You must not add requests to a group from within the group callback (or 1025=item * You must not add requests to a group from within the group callback (or
685any later time). 1026any later time).
686 1027
687=item * This does not harmonise well with C<max_outstanding>, so best do
688not combine C<aio_group> with it. Groups and feeders are recommended for
689this kind of concurrency-limiting.
690
691=back 1028=back
692 1029
693Their lifetime, simplified, looks like this: when they are empty, they 1030Their lifetime, simplified, looks like this: when they are empty, they
694will finish very quickly. If they contain only requests that are in the 1031will finish very quickly. If they contain only requests that are in the
695C<done> state, they will also finish. Otherwise they will continue to 1032C<done> state, they will also finish. Otherwise they will continue to
… …
718itself. Useful when you queued a lot of events but got a result early. 1055itself. Useful when you queued a lot of events but got a result early.
719 1056
720=item $grp->result (...) 1057=item $grp->result (...)
721 1058
722Set the result value(s) that will be passed to the group callback when all 1059Set the result value(s) that will be passed to the group callback when all
723subrequests have finished. By default, no argument will be passed. 1060subrequests have finished and set thre groups errno to the current value
1061of errno (just like calling C<errno> without an error number). By default,
1062no argument will be passed and errno is zero.
1063
1064=item $grp->errno ([$errno])
1065
1066Sets the group errno value to C<$errno>, or the current value of errno
1067when the argument is missing.
1068
1069Every aio request has an associated errno value that is restored when
1070the callback is invoked. This method lets you change this value from its
1071default (0).
1072
1073Calling C<result> will also set errno, so make sure you either set C<$!>
1074before the call to C<result>, or call c<errno> after it.
724 1075
725=item feed $grp $callback->($grp) 1076=item feed $grp $callback->($grp)
726 1077
727Sets a feeder/generator on this group: every group can have an attached 1078Sets a feeder/generator on this group: every group can have an attached
728generator that generates requests if idle. The idea behind this is that, 1079generator that generates requests if idle. The idea behind this is that,
… …
767 1118
768=back 1119=back
769 1120
770=head2 SUPPORT FUNCTIONS 1121=head2 SUPPORT FUNCTIONS
771 1122
1123=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1124
772=over 4 1125=over 4
773 1126
774=item $fileno = IO::AIO::poll_fileno 1127=item $fileno = IO::AIO::poll_fileno
775 1128
776Return the I<request result pipe file descriptor>. This filehandle must be 1129Return the I<request result pipe file descriptor>. This filehandle must be
… …
780 1133
781See C<poll_cb> for an example. 1134See C<poll_cb> for an example.
782 1135
783=item IO::AIO::poll_cb 1136=item IO::AIO::poll_cb
784 1137
785Process all outstanding events on the result pipe. You have to call this 1138Process some outstanding events on the result pipe. You have to call this
786regularly. Returns the number of events processed. Returns immediately 1139regularly. Returns the number of events processed. Returns immediately
787when no events are outstanding. 1140when no events are outstanding. The amount of events processed depends on
1141the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1142
1143If not all requests were processed for whatever reason, the filehandle
1144will still be ready when C<poll_cb> returns.
788 1145
789Example: Install an Event watcher that automatically calls 1146Example: Install an Event watcher that automatically calls
790IO::AIO::poll_cb with high priority: 1147IO::AIO::poll_cb with high priority:
791 1148
792 Event->io (fd => IO::AIO::poll_fileno, 1149 Event->io (fd => IO::AIO::poll_fileno,
793 poll => 'r', async => 1, 1150 poll => 'r', async => 1,
794 cb => \&IO::AIO::poll_cb); 1151 cb => \&IO::AIO::poll_cb);
795 1152
1153=item IO::AIO::max_poll_reqs $nreqs
1154
1155=item IO::AIO::max_poll_time $seconds
1156
1157These set the maximum number of requests (default C<0>, meaning infinity)
1158that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1159the maximum amount of time (default C<0>, meaning infinity) spent in
1160C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1161of time C<poll_cb> is allowed to use).
1162
1163Setting C<max_poll_time> to a non-zero value creates an overhead of one
1164syscall per request processed, which is not normally a problem unless your
1165callbacks are really really fast or your OS is really really slow (I am
1166not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1167
1168Setting these is useful if you want to ensure some level of
1169interactiveness when perl is not fast enough to process all requests in
1170time.
1171
1172For interactive programs, values such as C<0.01> to C<0.1> should be fine.
1173
1174Example: Install an Event watcher that automatically calls
1175IO::AIO::poll_cb with low priority, to ensure that other parts of the
1176program get the CPU sometimes even under high AIO load.
1177
1178 # try not to spend much more than 0.1s in poll_cb
1179 IO::AIO::max_poll_time 0.1;
1180
1181 # use a low priority so other tasks have priority
1182 Event->io (fd => IO::AIO::poll_fileno,
1183 poll => 'r', nice => 1,
1184 cb => &IO::AIO::poll_cb);
1185
796=item IO::AIO::poll_wait 1186=item IO::AIO::poll_wait
797 1187
1188If there are any outstanding requests and none of them in the result
798Wait till the result filehandle becomes ready for reading (simply does a 1189phase, wait till the result filehandle becomes ready for reading (simply
799C<select> on the filehandle. This is useful if you want to synchronously wait 1190does a C<select> on the filehandle. This is useful if you want to
800for some requests to finish). 1191synchronously wait for some requests to finish).
801 1192
802See C<nreqs> for an example. 1193See C<nreqs> for an example.
803 1194
1195=item IO::AIO::poll
1196
1197Waits until some requests have been handled.
1198
1199Returns the number of requests processed, but is otherwise strictly
1200equivalent to:
1201
1202 IO::AIO::poll_wait, IO::AIO::poll_cb
1203
804=item IO::AIO::nreqs 1204=item IO::AIO::flush
805 1205
806Returns the number of requests currently outstanding (i.e. for which their 1206Wait till all outstanding AIO requests have been handled.
807callback has not been invoked yet).
808 1207
809Example: wait till there are no outstanding requests anymore: 1208Strictly equivalent to:
810 1209
811 IO::AIO::poll_wait, IO::AIO::poll_cb 1210 IO::AIO::poll_wait, IO::AIO::poll_cb
812 while IO::AIO::nreqs; 1211 while IO::AIO::nreqs;
813 1212
814=item IO::AIO::flush 1213=back
815 1214
816Wait till all outstanding AIO requests have been handled. 1215=head3 CONTROLLING THE NUMBER OF THREADS
817 1216
818Strictly equivalent to: 1217=over
819
820 IO::AIO::poll_wait, IO::AIO::poll_cb
821 while IO::AIO::nreqs;
822
823=item IO::AIO::poll
824
825Waits until some requests have been handled.
826
827Strictly equivalent to:
828
829 IO::AIO::poll_wait, IO::AIO::poll_cb
830 if IO::AIO::nreqs;
831 1218
832=item IO::AIO::min_parallel $nthreads 1219=item IO::AIO::min_parallel $nthreads
833 1220
834Set the minimum number of AIO threads to C<$nthreads>. The current 1221Set the minimum number of AIO threads to C<$nthreads>. The current
835default is C<8>, which means eight asynchronous operations can execute 1222default is C<8>, which means eight asynchronous operations can execute
836concurrently at any one time (the number of outstanding requests, 1223concurrently at any one time (the number of outstanding requests,
837however, is unlimited). 1224however, is unlimited).
838 1225
839IO::AIO starts threads only on demand, when an AIO request is queued and 1226IO::AIO starts threads only on demand, when an AIO request is queued and
840no free thread exists. 1227no free thread exists. Please note that queueing up a hundred requests can
1228create demand for a hundred threads, even if it turns out that everything
1229is in the cache and could have been processed faster by a single thread.
841 1230
842It is recommended to keep the number of threads relatively low, as some 1231It is recommended to keep the number of threads relatively low, as some
843Linux kernel versions will scale negatively with the number of threads 1232Linux kernel versions will scale negatively with the number of threads
844(higher parallelity => MUCH higher latency). With current Linux 2.6 1233(higher parallelity => MUCH higher latency). With current Linux 2.6
845versions, 4-32 threads should be fine. 1234versions, 4-32 threads should be fine.
… …
859This module automatically runs C<max_parallel 0> at program end, to ensure 1248This module automatically runs C<max_parallel 0> at program end, to ensure
860that all threads are killed and that there are no outstanding requests. 1249that all threads are killed and that there are no outstanding requests.
861 1250
862Under normal circumstances you don't need to call this function. 1251Under normal circumstances you don't need to call this function.
863 1252
1253=item IO::AIO::max_idle $nthreads
1254
1255Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1256threads that did not get a request to process within 10 seconds). That
1257means if a thread becomes idle while C<$nthreads> other threads are also
1258idle, it will free its resources and exit.
1259
1260This is useful when you allow a large number of threads (e.g. 100 or 1000)
1261to allow for extremely high load situations, but want to free resources
1262under normal circumstances (1000 threads can easily consume 30MB of RAM).
1263
1264The default is probably ok in most situations, especially if thread
1265creation is fast. If thread creation is very slow on your system you might
1266want to use larger values.
1267
864=item $oldnreqs = IO::AIO::max_outstanding $nreqs 1268=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
865 1269
866[DEPRECATED] 1270This is a very bad function to use in interactive programs because it
1271blocks, and a bad way to reduce concurrency because it is inexact: Better
1272use an C<aio_group> together with a feed callback.
867 1273
868Sets the maximum number of outstanding requests to C<$nreqs>. If you 1274Sets the maximum number of outstanding requests to C<$nreqs>. If you
869try to queue up more than this number of requests, the caller will block until 1275do queue up more than this number of requests, the next call to the
870some requests have been handled. 1276C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1277function will block until the limit is no longer exceeded.
871 1278
872The default is very large, so normally there is no practical limit. If you 1279The default value is very large, so there is no practical limit on the
873queue up many requests in a loop it often improves speed if you set 1280number of outstanding requests.
874this to a relatively low number, such as C<100>.
875 1281
876This function does not work well together with C<aio_group>'s, and their 1282You can still queue as many requests as you want. Therefore,
877feeder interface is better suited to limiting concurrency, so do not use 1283C<max_oustsanding> is mainly useful in simple scripts (with low values) or
878this function. 1284as a stop gap to shield against fatal memory overflow (with large values).
879
880Under normal circumstances you don't need to call this function.
881 1285
882=back 1286=back
883 1287
1288=head3 STATISTICAL INFORMATION
1289
1290=over
1291
1292=item IO::AIO::nreqs
1293
1294Returns the number of requests currently in the ready, execute or pending
1295states (i.e. for which their callback has not been invoked yet).
1296
1297Example: wait till there are no outstanding requests anymore:
1298
1299 IO::AIO::poll_wait, IO::AIO::poll_cb
1300 while IO::AIO::nreqs;
1301
1302=item IO::AIO::nready
1303
1304Returns the number of requests currently in the ready state (not yet
1305executed).
1306
1307=item IO::AIO::npending
1308
1309Returns the number of requests currently in the pending state (executed,
1310but not yet processed by poll_cb).
1311
1312=back
1313
884=cut 1314=cut
885 1315
886# support function to convert a fd into a perl filehandle
887sub _fd2fh {
888 return undef if $_[0] < 0;
889
890 # try to generate nice filehandles
891 my $sym = "IO::AIO::fd#$_[0]";
892 local *$sym;
893
894 open *$sym, "+<&=$_[0]" # usually works under any unix
895 or open *$sym, "<&=$_[0]" # cygwin needs this
896 or open *$sym, ">&=$_[0]" # or this
897 or return undef;
898
899 *$sym
900}
901
902min_parallel 8; 1316min_parallel 8;
903 1317
904END { 1318END { flush }
905 max_parallel 0;
906}
907 1319
9081; 13201;
909 1321
910=head2 FORK BEHAVIOUR 1322=head2 FORK BEHAVIOUR
911 1323
… …
931bytes of memory. In addition, stat requests need a stat buffer (possibly 1343bytes of memory. In addition, stat requests need a stat buffer (possibly
932a few hundred bytes), readdir requires a result buffer and so on. Perl 1344a few hundred bytes), readdir requires a result buffer and so on. Perl
933scalars and other data passed into aio requests will also be locked and 1345scalars and other data passed into aio requests will also be locked and
934will consume memory till the request has entered the done state. 1346will consume memory till the request has entered the done state.
935 1347
936This is now awfully much, so queuing lots of requests is not usually a 1348This is not awfully much, so queuing lots of requests is not usually a
937problem. 1349problem.
938 1350
939Per-thread usage: 1351Per-thread usage:
940 1352
941In the execution phase, some aio requests require more memory for 1353In the execution phase, some aio requests require more memory for

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines