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Revision 1.116 by root, Wed Oct 3 21:27:51 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
… …
50 51
51=head1 DESCRIPTION 52=head1 DESCRIPTION
52 53
53This module implements asynchronous I/O using whatever means your 54This module implements asynchronous I/O using whatever means your
54operating system supports. 55operating system supports.
56
57Asynchronous means that operations that can normally block your program
58(e.g. reading from disk) will be done asynchronously: the operation
59will still block, but you can do something else in the meantime. This
60is extremely useful for programs that need to stay interactive even
61when doing heavy I/O (GUI programs, high performance network servers
62etc.), but can also be used to easily do operations in parallel that are
63normally done sequentially, e.g. stat'ing many files, which is much faster
64on a RAID volume or over NFS when you do a number of stat operations
65concurrently.
66
67While most of this works on all types of file descriptors (for
68example sockets), using these functions on file descriptors that
69support nonblocking operation (again, sockets, pipes etc.) is very
70inefficient. Use an event loop for that (such as the L<Event|Event>
71module): IO::AIO will naturally fit into such an event loop itself.
55 72
56In this version, a number of threads are started that execute your 73In this version, a number of threads are started that execute your
57requests and signal their completion. You don't need thread support 74requests and signal their completion. You don't need thread support
58in perl, and the threads created by this module will not be visible 75in 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 76to perl. In the future, this module might make use of the native aio
60functions available on many operating systems. However, they are often 77functions available on many operating systems. However, they are often
61not well-supported or restricted (Linux doesn't allow them on normal 78not well-supported or restricted (GNU/Linux doesn't allow them on normal
62files currently, for example), and they would only support aio_read and 79files currently, for example), and they would only support aio_read and
63aio_write, so the remaining functionality would have to be implemented 80aio_write, so the remaining functionality would have to be implemented
64using threads anyway. 81using threads anyway.
65 82
66Although the module will work with in the presence of other (Perl-) 83Although the module will work in the presence of other (Perl-) threads,
67threads, it is currently not reentrant in any way, so use appropriate 84it is currently not reentrant in any way, so use appropriate locking
68locking yourself, always call C<poll_cb> from within the same thread, or 85yourself, always call C<poll_cb> from within the same thread, or never
69never call C<poll_cb> (or other C<aio_> functions) recursively. 86call C<poll_cb> (or other C<aio_> functions) recursively.
87
88=head2 EXAMPLE
89
90This is a simple example that uses the Event module and loads
91F</etc/passwd> asynchronously:
92
93 use Fcntl;
94 use Event;
95 use IO::AIO;
96
97 # register the IO::AIO callback with Event
98 Event->io (fd => IO::AIO::poll_fileno,
99 poll => 'r',
100 cb => \&IO::AIO::poll_cb);
101
102 # queue the request to open /etc/passwd
103 aio_open "/etc/passwd", O_RDONLY, 0, sub {
104 my $fh = shift
105 or die "error while opening: $!";
106
107 # stat'ing filehandles is generally non-blocking
108 my $size = -s $fh;
109
110 # queue a request to read the file
111 my $contents;
112 aio_read $fh, 0, $size, $contents, 0, sub {
113 $_[0] == $size
114 or die "short read: $!";
115
116 close $fh;
117
118 # file contents now in $contents
119 print $contents;
120
121 # exit event loop and program
122 Event::unloop;
123 };
124 };
125
126 # possibly queue up other requests, or open GUI windows,
127 # check for sockets etc. etc.
128
129 # process events as long as there are some:
130 Event::loop;
70 131
71=head1 REQUEST ANATOMY AND LIFETIME 132=head1 REQUEST ANATOMY AND LIFETIME
72 133
73Every C<aio_*> function creates a request. which is a C data structure not 134Every C<aio_*> function creates a request. which is a C data structure not
74directly visible to Perl. 135directly visible to Perl.
… …
116Request has reached the end of its lifetime and holds no resources anymore 177Request 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 178(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 179aio request is severed and calling its methods will either do nothing or
119result in a runtime error). 180result in a runtime error).
120 181
182=back
183
121=cut 184=cut
122 185
123package IO::AIO; 186package IO::AIO;
124 187
125no warnings; 188no warnings;
126use strict 'vars'; 189use strict 'vars';
127 190
128use base 'Exporter'; 191use base 'Exporter';
129 192
130BEGIN { 193BEGIN {
131 our $VERSION = '2.0'; 194 our $VERSION = '2.5';
132 195
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 196 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 197 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 198 aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
136 aio_group aio_nop); 199 aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
200 aio_chown aio_chmod aio_utime aio_truncate);
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 201 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 202 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel nreqs nready npending); 203 min_parallel max_parallel max_idle
204 nreqs nready npending nthreads
205 max_poll_time max_poll_reqs);
140 206
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 207 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 208
143 require XSLoader; 209 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 210 XSLoader::load ("IO::AIO", $VERSION);
145} 211}
146 212
147=head1 FUNCTIONS 213=head1 FUNCTIONS
148 214
149=head2 AIO FUNCTIONS 215=head2 AIO REQUEST FUNCTIONS
150 216
151All the C<aio_*> calls are more or less thin wrappers around the syscall 217All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 218with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 219and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 220which must be a code reference. This code reference will get called with
… …
157syscall has been executed asynchronously. 223syscall has been executed asynchronously.
158 224
159All functions expecting a filehandle keep a copy of the filehandle 225All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 226internally until the request has finished.
161 227
162All requests return objects of type L<IO::AIO::REQ> that allow further 228All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 229further manipulation of those requests while they are in-flight.
164 230
165The pathnames you pass to these routines I<must> be absolute and 231The 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 232encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 233request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 234changed. Alternatively, you can make sure that you never change the
169current working directory. 235current working directory anywhere in the program and then use relative
236paths.
170 237
171To encode pathnames to byte form, either make sure you either: a) 238To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 239in 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 240tinkering, 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 241your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 242environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 243use something else to ensure your scalar has the correct contents.
244
245This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246handles correctly wether it is set or not.
177 247
178=over 4 248=over 4
179 249
180=item $prev_pri = aioreq_pri [$pri] 250=item $prev_pri = aioreq_pri [$pri]
181 251
… …
201 aio_read $_[0], ..., sub { 271 aio_read $_[0], ..., sub {
202 ... 272 ...
203 }; 273 };
204 }; 274 };
205 275
276
206=item aioreq_nice $pri_adjust 277=item aioreq_nice $pri_adjust
207 278
208Similar to C<aioreq_pri>, but subtracts the given value from the current 279Similar to C<aioreq_pri>, but subtracts the given value from the current
209priority, so effects are cumulative. 280priority, so the effect is cumulative.
281
210 282
211=item aio_open $pathname, $flags, $mode, $callback->($fh) 283=item aio_open $pathname, $flags, $mode, $callback->($fh)
212 284
213Asynchronously open or create a file and call the callback with a newly 285Asynchronously open or create a file and call the callback with a newly
214created filehandle for the file. 286created filehandle for the file.
… …
220list. They are the same as used by C<sysopen>. 292list. They are the same as used by C<sysopen>.
221 293
222Likewise, C<$mode> specifies the mode of the newly created file, if it 294Likewise, C<$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>, 295didn'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, 296except 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). 297and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
298by the umask in effect then the request is being executed, so better never
299change the umask.
226 300
227Example: 301Example:
228 302
229 aio_open "/etc/passwd", O_RDONLY, 0, sub { 303 aio_open "/etc/passwd", O_RDONLY, 0, sub {
230 if ($_[0]) { 304 if ($_[0]) {
… …
233 } else { 307 } else {
234 die "open failed: $!\n"; 308 die "open failed: $!\n";
235 } 309 }
236 }; 310 };
237 311
312
238=item aio_close $fh, $callback->($status) 313=item aio_close $fh, $callback->($status)
239 314
240Asynchronously close a file and call the callback with the result 315Asynchronously close a file and call the callback with the result
241code. I<WARNING:> although accepted, you should not pass in a perl 316code.
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.
245 317
246This is supposed to be a bug in the API, so that might change. It's 318Unlike the other functions operating on files, this function uses the
247therefore best to avoid this function. 319PerlIO layer to close the filehandle. The reason is that the PerlIO API
320insists on closing the underlying fd itself, no matter what, and doesn't
321allow modifications to the fd. Unfortunately, it is not clear that you can
322call PerlIO from different threads (actually, its quite clear that this
323won't work in some cases), so while it likely works perfectly with simple
324file handles (such as the ones created by C<aio_open>) it might fail in
325interesting ways for others.
326
327Having said that, aio_close tries to clean up the filehandle as much as
328possible before handing it to an io thread, and generally does work.
329
248 330
249=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 331=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250 332
251=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 333=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252 334
253Reads or writes C<length> bytes from the specified C<fh> and C<offset> 335Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
254into the scalar given by C<data> and offset C<dataoffset> and calls the 336into the scalar given by C<$data> and offset C<$dataoffset> and calls the
255callback without the actual number of bytes read (or -1 on error, just 337callback without the actual number of bytes read (or -1 on error, just
256like the syscall). 338like the syscall).
257 339
340If C<$offset> is undefined, then the current file descriptor offset will
341be used (and updated), otherwise the file descriptor offset will not be
342changed by these calls.
343
344If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
345
346If C<$dataoffset> is less than zero, it will be counted from the end of
347C<$data>.
348
258The C<$data> scalar I<MUST NOT> be modified in any way while the request 349The C<$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 350is outstanding. Modifying it can result in segfaults or World War III (if
260necessary/optional hardware is installed). 351the necessary/optional hardware is installed).
261 352
262Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 353Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263offset C<0> within the scalar: 354offset C<0> within the scalar:
264 355
265 aio_read $fh, 7, 15, $buffer, 0, sub { 356 aio_read $fh, 7, 15, $buffer, 0, sub {
266 $_[0] > 0 or die "read error: $!"; 357 $_[0] > 0 or die "read error: $!";
267 print "read $_[0] bytes: <$buffer>\n"; 358 print "read $_[0] bytes: <$buffer>\n";
268 }; 359 };
269 360
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}
344 361
345=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 362=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
346 363
347Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 364Tries 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 365reading 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 379C<$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 380bytes 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 381provides 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 382value equals C<$length> one can assume that C<$length> bytes have been
366read. 383read.
384
367 385
368=item aio_readahead $fh,$offset,$length, $callback->($retval) 386=item aio_readahead $fh,$offset,$length, $callback->($retval)
369 387
370C<aio_readahead> populates the page cache with data from a file so that 388C<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> 389subsequent 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. 395file. The current file offset of the file is left unchanged.
378 396
379If that syscall doesn't exist (likely if your OS isn't Linux) it will be 397If 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. 398emulated by simply reading the data, which would have a similar effect.
381 399
400
382=item aio_stat $fh_or_path, $callback->($status) 401=item aio_stat $fh_or_path, $callback->($status)
383 402
384=item aio_lstat $fh, $callback->($status) 403=item aio_lstat $fh, $callback->($status)
385 404
386Works like perl's C<stat> or C<lstat> in void context. The callback will 405Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
399 aio_stat "/etc/passwd", sub { 418 aio_stat "/etc/passwd", sub {
400 $_[0] and die "stat failed: $!"; 419 $_[0] and die "stat failed: $!";
401 print "size is ", -s _, "\n"; 420 print "size is ", -s _, "\n";
402 }; 421 };
403 422
423
424=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
425
426Works like perl's C<utime> function (including the special case of $atime
427and $mtime being undef). Fractional times are supported if the underlying
428syscalls support them.
429
430When called with a pathname, uses utimes(2) if available, otherwise
431utime(2). If called on a file descriptor, uses futimes(2) if available,
432otherwise returns ENOSYS, so this is not portable.
433
434Examples:
435
436 # set atime and mtime to current time (basically touch(1)):
437 aio_utime "path", undef, undef;
438 # set atime to current time and mtime to beginning of the epoch:
439 aio_utime "path", time, undef; # undef==0
440
441
442=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
443
444Works like perl's C<chown> function, except that C<undef> for either $uid
445or $gid is being interpreted as "do not change" (but -1 can also be used).
446
447Examples:
448
449 # same as "chown root path" in the shell:
450 aio_chown "path", 0, -1;
451 # same as above:
452 aio_chown "path", 0, undef;
453
454
455=item aio_truncate $fh_or_path, $offset, $callback->($status)
456
457Works like truncate(2) or ftruncate(2).
458
459
460=item aio_chmod $fh_or_path, $mode, $callback->($status)
461
462Works like perl's C<chmod> function.
463
464
404=item aio_unlink $pathname, $callback->($status) 465=item aio_unlink $pathname, $callback->($status)
405 466
406Asynchronously unlink (delete) a file and call the callback with the 467Asynchronously unlink (delete) a file and call the callback with the
407result code. 468result code.
408 469
470
471=item aio_mknod $path, $mode, $dev, $callback->($status)
472
473[EXPERIMENTAL]
474
475Asynchronously create a device node (or fifo). See mknod(2).
476
477The only (POSIX-) portable way of calling this function is:
478
479 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
480
481
409=item aio_link $srcpath, $dstpath, $callback->($status) 482=item aio_link $srcpath, $dstpath, $callback->($status)
410 483
411Asynchronously create a new link to the existing object at C<$srcpath> at 484Asynchronously create a new link to the existing object at C<$srcpath> at
412the path C<$dstpath> and call the callback with the result code. 485the path C<$dstpath> and call the callback with the result code.
413 486
487
414=item aio_symlink $srcpath, $dstpath, $callback->($status) 488=item aio_symlink $srcpath, $dstpath, $callback->($status)
415 489
416Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 490Asynchronously 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. 491the path C<$dstpath> and call the callback with the result code.
418 492
493
494=item aio_readlink $path, $callback->($link)
495
496Asynchronously read the symlink specified by C<$path> and pass it to
497the callback. If an error occurs, nothing or undef gets passed to the
498callback.
499
500
419=item aio_rename $srcpath, $dstpath, $callback->($status) 501=item aio_rename $srcpath, $dstpath, $callback->($status)
420 502
421Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 503Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422rename(2) and call the callback with the result code. 504rename(2) and call the callback with the result code.
423 505
506
507=item aio_mkdir $pathname, $mode, $callback->($status)
508
509Asynchronously mkdir (create) a directory and call the callback with
510the result code. C<$mode> will be modified by the umask at the time the
511request is executed, so do not change your umask.
512
513
424=item aio_rmdir $pathname, $callback->($status) 514=item aio_rmdir $pathname, $callback->($status)
425 515
426Asynchronously rmdir (delete) a directory and call the callback with the 516Asynchronously rmdir (delete) a directory and call the callback with the
427result code. 517result code.
518
428 519
429=item aio_readdir $pathname, $callback->($entries) 520=item aio_readdir $pathname, $callback->($entries)
430 521
431Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 522Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
432directory (i.e. opendir + readdir + closedir). The entries will not be 523directory (i.e. opendir + readdir + closedir). The entries will not be
433sorted, and will B<NOT> include the C<.> and C<..> entries. 524sorted, and will B<NOT> include the C<.> and C<..> entries.
434 525
435The callback a single argument which is either C<undef> or an array-ref 526The callback a single argument which is either C<undef> or an array-ref
436with the filenames. 527with the filenames.
528
529
530=item aio_load $path, $data, $callback->($status)
531
532This is a composite request that tries to fully load the given file into
533memory. Status is the same as with aio_read.
534
535=cut
536
537sub aio_load($$;$) {
538 aio_block {
539 my ($path, undef, $cb) = @_;
540 my $data = \$_[1];
541
542 my $pri = aioreq_pri;
543 my $grp = aio_group $cb;
544
545 aioreq_pri $pri;
546 add $grp aio_open $path, O_RDONLY, 0, sub {
547 my $fh = shift
548 or return $grp->result (-1);
549
550 aioreq_pri $pri;
551 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
552 $grp->result ($_[0]);
553 };
554 };
555
556 $grp
557 }
558}
559
560=item aio_copy $srcpath, $dstpath, $callback->($status)
561
562Try to copy the I<file> (directories not supported as either source or
563destination) from C<$srcpath> to C<$dstpath> and call the callback with
564the C<0> (error) or C<-1> ok.
565
566This is a composite request that it creates the destination file with
567mode 0200 and copies the contents of the source file into it using
568C<aio_sendfile>, followed by restoring atime, mtime, access mode and
569uid/gid, in that order.
570
571If an error occurs, the partial destination file will be unlinked, if
572possible, except when setting atime, mtime, access mode and uid/gid, where
573errors are being ignored.
574
575=cut
576
577sub aio_copy($$;$) {
578 aio_block {
579 my ($src, $dst, $cb) = @_;
580
581 my $pri = aioreq_pri;
582 my $grp = aio_group $cb;
583
584 aioreq_pri $pri;
585 add $grp aio_open $src, O_RDONLY, 0, sub {
586 if (my $src_fh = $_[0]) {
587 my @stat = stat $src_fh;
588
589 aioreq_pri $pri;
590 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
591 if (my $dst_fh = $_[0]) {
592 aioreq_pri $pri;
593 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
594 if ($_[0] == $stat[7]) {
595 $grp->result (0);
596 close $src_fh;
597
598 # those should not normally block. should. should.
599 utime $stat[8], $stat[9], $dst;
600 chmod $stat[2] & 07777, $dst_fh;
601 chown $stat[4], $stat[5], $dst_fh;
602 close $dst_fh;
603 } else {
604 $grp->result (-1);
605 close $src_fh;
606 close $dst_fh;
607
608 aioreq $pri;
609 add $grp aio_unlink $dst;
610 }
611 };
612 } else {
613 $grp->result (-1);
614 }
615 },
616
617 } else {
618 $grp->result (-1);
619 }
620 };
621
622 $grp
623 }
624}
625
626=item aio_move $srcpath, $dstpath, $callback->($status)
627
628Try to move the I<file> (directories not supported as either source or
629destination) from C<$srcpath> to C<$dstpath> and call the callback with
630the C<0> (error) or C<-1> ok.
631
632This is a composite request that tries to rename(2) the file first. If
633rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
634that is successful, unlinking the C<$srcpath>.
635
636=cut
637
638sub aio_move($$;$) {
639 aio_block {
640 my ($src, $dst, $cb) = @_;
641
642 my $pri = aioreq_pri;
643 my $grp = aio_group $cb;
644
645 aioreq_pri $pri;
646 add $grp aio_rename $src, $dst, sub {
647 if ($_[0] && $! == EXDEV) {
648 aioreq_pri $pri;
649 add $grp aio_copy $src, $dst, sub {
650 $grp->result ($_[0]);
651
652 if (!$_[0]) {
653 aioreq_pri $pri;
654 add $grp aio_unlink $src;
655 }
656 };
657 } else {
658 $grp->result ($_[0]);
659 }
660 };
661
662 $grp
663 }
664}
437 665
438=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 666=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439 667
440Scans a directory (similar to C<aio_readdir>) but additionally tries to 668Scans a directory (similar to C<aio_readdir>) but additionally tries to
441efficiently separate the entries of directory C<$path> into two sets of 669efficiently separate the entries of directory C<$path> into two sets of
… …
443recurse into (everything else, including symlinks to directories). 671recurse into (everything else, including symlinks to directories).
444 672
445C<aio_scandir> is a composite request that creates of many sub requests_ 673C<aio_scandir> is a composite request that creates of many sub requests_
446C<$maxreq> specifies the maximum number of outstanding aio requests that 674C<$maxreq> specifies the maximum number of outstanding aio requests that
447this function generates. If it is C<< <= 0 >>, then a suitable default 675this function generates. If it is C<< <= 0 >>, then a suitable default
448will be chosen (currently 6). 676will be chosen (currently 4).
449 677
450On error, the callback is called without arguments, otherwise it receives 678On error, the callback is called without arguments, otherwise it receives
451two array-refs with path-relative entry names. 679two array-refs with path-relative entry names.
452 680
453Example: 681Example:
… …
487as those tend to return 0 or 1 as link counts, which disables the 715as those tend to return 0 or 1 as link counts, which disables the
488directory counting heuristic. 716directory counting heuristic.
489 717
490=cut 718=cut
491 719
492sub aio_scandir($$$) { 720sub aio_scandir($$;$) {
721 aio_block {
493 my ($path, $maxreq, $cb) = @_; 722 my ($path, $maxreq, $cb) = @_;
494 723
495 my $pri = aioreq_pri; 724 my $pri = aioreq_pri;
496 725
497 my $grp = aio_group $cb; 726 my $grp = aio_group $cb;
498 727
499 $maxreq = 6 if $maxreq <= 0; 728 $maxreq = 4 if $maxreq <= 0;
500 729
501 # stat once 730 # 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; 731 aioreq_pri $pri;
510 add $grp aio_readdir $path, sub { 732 add $grp aio_stat $path, sub {
511 my $entries = shift
512 or return $grp->result (); 733 return $grp->result () if $_[0];
734 my $now = time;
735 my $hash1 = join ":", (stat _)[0,1,3,7,9];
513 736
514 # stat the dir another time 737 # read the directory entries
515 aioreq_pri $pri; 738 aioreq_pri $pri;
739 add $grp aio_readdir $path, sub {
740 my $entries = shift
741 or return $grp->result ();
742
743 # stat the dir another time
744 aioreq_pri $pri;
516 add $grp aio_stat $path, sub { 745 add $grp aio_stat $path, sub {
517 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 746 my $hash2 = join ":", (stat _)[0,1,3,7,9];
518 747
519 my $ndirs; 748 my $ndirs;
520 749
521 # take the slow route if anything looks fishy 750 # take the slow route if anything looks fishy
522 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 751 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523 $ndirs = -1; 752 $ndirs = -1;
524 } else { 753 } else {
525 # if nlink == 2, we are finished 754 # if nlink == 2, we are finished
526 # on non-posix-fs's, we rely on nlink < 2 755 # on non-posix-fs's, we rely on nlink < 2
527 $ndirs = (stat _)[3] - 2 756 $ndirs = (stat _)[3] - 2
528 or return $grp->result ([], $entries); 757 or return $grp->result ([], $entries);
529 } 758 }
530 759
531 # sort into likely dirs and likely nondirs 760 # sort into likely dirs and likely nondirs
532 # dirs == files without ".", short entries first 761 # dirs == files without ".", short entries first
533 $entries = [map $_->[0], 762 $entries = [map $_->[0],
534 sort { $b->[1] cmp $a->[1] } 763 sort { $b->[1] cmp $a->[1] }
535 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 764 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
536 @$entries]; 765 @$entries];
537 766
538 my (@dirs, @nondirs); 767 my (@dirs, @nondirs);
539 768
540 my $statgrp = add $grp aio_group sub { 769 my $statgrp = add $grp aio_group sub {
541 $grp->result (\@dirs, \@nondirs); 770 $grp->result (\@dirs, \@nondirs);
542 }; 771 };
543 772
544 limit $statgrp $maxreq; 773 limit $statgrp $maxreq;
545 feed $statgrp sub { 774 feed $statgrp sub {
546 return unless @$entries; 775 return unless @$entries;
547 my $entry = pop @$entries; 776 my $entry = pop @$entries;
548 777
549 aioreq_pri $pri; 778 aioreq_pri $pri;
550 add $statgrp aio_stat "$path/$entry/.", sub { 779 add $statgrp aio_stat "$path/$entry/.", sub {
551 if ($_[0] < 0) { 780 if ($_[0] < 0) {
552 push @nondirs, $entry; 781 push @nondirs, $entry;
553 } else { 782 } else {
554 # need to check for real directory 783 # need to check for real directory
555 aioreq_pri $pri; 784 aioreq_pri $pri;
556 add $statgrp aio_lstat "$path/$entry", sub { 785 add $statgrp aio_lstat "$path/$entry", sub {
557 if (-d _) { 786 if (-d _) {
558 push @dirs, $entry; 787 push @dirs, $entry;
559 788
560 unless (--$ndirs) { 789 unless (--$ndirs) {
561 push @nondirs, @$entries; 790 push @nondirs, @$entries;
562 feed $statgrp; 791 feed $statgrp;
792 }
793 } else {
794 push @nondirs, $entry;
563 } 795 }
564 } else {
565 push @nondirs, $entry;
566 } 796 }
567 } 797 }
568 } 798 };
569 }; 799 };
570 }; 800 };
571 }; 801 };
572 }; 802 };
803
804 $grp
573 }; 805 }
806}
574 807
808=item aio_rmtree $path, $callback->($status)
809
810Delete a directory tree starting (and including) C<$path>, return the
811status of the final C<rmdir> only. This is a composite request that
812uses C<aio_scandir> to recurse into and rmdir directories, and unlink
813everything else.
814
815=cut
816
817sub aio_rmtree;
818sub aio_rmtree($;$) {
819 aio_block {
820 my ($path, $cb) = @_;
821
822 my $pri = aioreq_pri;
823 my $grp = aio_group $cb;
824
825 aioreq_pri $pri;
826 add $grp aio_scandir $path, 0, sub {
827 my ($dirs, $nondirs) = @_;
828
829 my $dirgrp = aio_group sub {
830 add $grp aio_rmdir $path, sub {
831 $grp->result ($_[0]);
832 };
833 };
834
835 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
836 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
837
838 add $grp $dirgrp;
839 };
840
575 $grp 841 $grp
842 }
576} 843}
577 844
578=item aio_fsync $fh, $callback->($status) 845=item aio_fsync $fh, $callback->($status)
579 846
580Asynchronously call fsync on the given filehandle and call the callback 847Asynchronously call fsync on the given filehandle and call the callback
… …
794 1061
795=back 1062=back
796 1063
797=head2 SUPPORT FUNCTIONS 1064=head2 SUPPORT FUNCTIONS
798 1065
1066=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1067
799=over 4 1068=over 4
800 1069
801=item $fileno = IO::AIO::poll_fileno 1070=item $fileno = IO::AIO::poll_fileno
802 1071
803Return the I<request result pipe file descriptor>. This filehandle must be 1072Return the I<request result pipe file descriptor>. This filehandle must be
… …
807 1076
808See C<poll_cb> for an example. 1077See C<poll_cb> for an example.
809 1078
810=item IO::AIO::poll_cb 1079=item IO::AIO::poll_cb
811 1080
812Process all outstanding events on the result pipe. You have to call this 1081Process some outstanding events on the result pipe. You have to call this
813regularly. Returns the number of events processed. Returns immediately 1082regularly. Returns the number of events processed. Returns immediately
814when no events are outstanding. 1083when no events are outstanding. The amount of events processed depends on
1084the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
815 1085
816If not all requests were processed for whatever reason, the filehandle 1086If not all requests were processed for whatever reason, the filehandle
817will still be ready when C<poll_cb> returns. 1087will still be ready when C<poll_cb> returns.
818 1088
819Example: Install an Event watcher that automatically calls 1089Example: Install an Event watcher that automatically calls
… …
821 1091
822 Event->io (fd => IO::AIO::poll_fileno, 1092 Event->io (fd => IO::AIO::poll_fileno,
823 poll => 'r', async => 1, 1093 poll => 'r', async => 1,
824 cb => \&IO::AIO::poll_cb); 1094 cb => \&IO::AIO::poll_cb);
825 1095
826=item IO::AIO::poll_some $max_requests 1096=item IO::AIO::max_poll_reqs $nreqs
827 1097
828Similar to C<poll_cb>, but only processes up to C<$max_requests> requests 1098=item IO::AIO::max_poll_time $seconds
829at a time.
830 1099
831Useful if you want to ensure some level of interactiveness when perl is 1100These set the maximum number of requests (default C<0>, meaning infinity)
832not fast enough to process all requests in time. 1101that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1102the maximum amount of time (default C<0>, meaning infinity) spent in
1103C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1104of time C<poll_cb> is allowed to use).
1105
1106Setting C<max_poll_time> to a non-zero value creates an overhead of one
1107syscall per request processed, which is not normally a problem unless your
1108callbacks are really really fast or your OS is really really slow (I am
1109not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1110
1111Setting these is useful if you want to ensure some level of
1112interactiveness when perl is not fast enough to process all requests in
1113time.
1114
1115For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833 1116
834Example: Install an Event watcher that automatically calls 1117Example: Install an Event watcher that automatically calls
835IO::AIO::poll_some with low priority, to ensure that other parts of the 1118IO::AIO::poll_cb with low priority, to ensure that other parts of the
836program get the CPU sometimes even under high AIO load. 1119program get the CPU sometimes even under high AIO load.
837 1120
1121 # try not to spend much more than 0.1s in poll_cb
1122 IO::AIO::max_poll_time 0.1;
1123
1124 # use a low priority so other tasks have priority
838 Event->io (fd => IO::AIO::poll_fileno, 1125 Event->io (fd => IO::AIO::poll_fileno,
839 poll => 'r', nice => 1, 1126 poll => 'r', nice => 1,
840 cb => sub { IO::AIO::poll_some 256 }); 1127 cb => &IO::AIO::poll_cb);
841 1128
842=item IO::AIO::poll_wait 1129=item IO::AIO::poll_wait
843 1130
1131If there are any outstanding requests and none of them in the result
844Wait till the result filehandle becomes ready for reading (simply does a 1132phase, wait till the result filehandle becomes ready for reading (simply
845C<select> on the filehandle. This is useful if you want to synchronously wait 1133does a C<select> on the filehandle. This is useful if you want to
846for some requests to finish). 1134synchronously wait for some requests to finish).
847 1135
848See C<nreqs> for an example. 1136See C<nreqs> for an example.
849 1137
1138=item IO::AIO::poll
1139
1140Waits until some requests have been handled.
1141
1142Returns the number of requests processed, but is otherwise strictly
1143equivalent to:
1144
1145 IO::AIO::poll_wait, IO::AIO::poll_cb
1146
850=item IO::AIO::nreqs 1147=item IO::AIO::flush
851 1148
852Returns the number of requests currently in the ready, execute or pending 1149Wait till all outstanding AIO requests have been handled.
853states (i.e. for which their callback has not been invoked yet).
854 1150
855Example: wait till there are no outstanding requests anymore: 1151Strictly equivalent to:
856 1152
857 IO::AIO::poll_wait, IO::AIO::poll_cb 1153 IO::AIO::poll_wait, IO::AIO::poll_cb
858 while IO::AIO::nreqs; 1154 while IO::AIO::nreqs;
859 1155
860=item IO::AIO::nready 1156=back
861 1157
862Returns the number of requests currently in the ready state (not yet 1158=head3 CONTROLLING THE NUMBER OF THREADS
863executed).
864 1159
865=item IO::AIO::npending 1160=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 1161
888=item IO::AIO::min_parallel $nthreads 1162=item IO::AIO::min_parallel $nthreads
889 1163
890Set the minimum number of AIO threads to C<$nthreads>. The current 1164Set the minimum number of AIO threads to C<$nthreads>. The current
891default is C<8>, which means eight asynchronous operations can execute 1165default is C<8>, which means eight asynchronous operations can execute
892concurrently at any one time (the number of outstanding requests, 1166concurrently at any one time (the number of outstanding requests,
893however, is unlimited). 1167however, is unlimited).
894 1168
895IO::AIO starts threads only on demand, when an AIO request is queued and 1169IO::AIO starts threads only on demand, when an AIO request is queued and
896no free thread exists. 1170no free thread exists. Please note that queueing up a hundred requests can
1171create demand for a hundred threads, even if it turns out that everything
1172is in the cache and could have been processed faster by a single thread.
897 1173
898It is recommended to keep the number of threads relatively low, as some 1174It is recommended to keep the number of threads relatively low, as some
899Linux kernel versions will scale negatively with the number of threads 1175Linux kernel versions will scale negatively with the number of threads
900(higher parallelity => MUCH higher latency). With current Linux 2.6 1176(higher parallelity => MUCH higher latency). With current Linux 2.6
901versions, 4-32 threads should be fine. 1177versions, 4-32 threads should be fine.
… …
915This module automatically runs C<max_parallel 0> at program end, to ensure 1191This module automatically runs C<max_parallel 0> at program end, to ensure
916that all threads are killed and that there are no outstanding requests. 1192that all threads are killed and that there are no outstanding requests.
917 1193
918Under normal circumstances you don't need to call this function. 1194Under normal circumstances you don't need to call this function.
919 1195
1196=item IO::AIO::max_idle $nthreads
1197
1198Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1199threads that did not get a request to process within 10 seconds). That
1200means if a thread becomes idle while C<$nthreads> other threads are also
1201idle, it will free its resources and exit.
1202
1203This is useful when you allow a large number of threads (e.g. 100 or 1000)
1204to allow for extremely high load situations, but want to free resources
1205under normal circumstances (1000 threads can easily consume 30MB of RAM).
1206
1207The default is probably ok in most situations, especially if thread
1208creation is fast. If thread creation is very slow on your system you might
1209want to use larger values.
1210
920=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1211=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
921 1212
922This is a very bad function to use in interactive programs because it 1213This is a very bad function to use in interactive programs because it
923blocks, and a bad way to reduce concurrency because it is inexact: Better 1214blocks, and a bad way to reduce concurrency because it is inexact: Better
924use an C<aio_group> together with a feed callback. 1215use an C<aio_group> together with a feed callback.
925 1216
926Sets the maximum number of outstanding requests to C<$nreqs>. If you 1217Sets 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 1218do 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>) 1219C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
929function will block until the limit is no longer exceeded. 1220function will block until the limit is no longer exceeded.
930 1221
931The default value is very large, so there is no practical limit on the 1222The default value is very large, so there is no practical limit on the
932number of outstanding requests. 1223number of outstanding requests.
… …
935C<max_oustsanding> is mainly useful in simple scripts (with low values) or 1226C<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). 1227as a stop gap to shield against fatal memory overflow (with large values).
937 1228
938=back 1229=back
939 1230
1231=head3 STATISTICAL INFORMATION
1232
1233=over
1234
1235=item IO::AIO::nreqs
1236
1237Returns the number of requests currently in the ready, execute or pending
1238states (i.e. for which their callback has not been invoked yet).
1239
1240Example: wait till there are no outstanding requests anymore:
1241
1242 IO::AIO::poll_wait, IO::AIO::poll_cb
1243 while IO::AIO::nreqs;
1244
1245=item IO::AIO::nready
1246
1247Returns the number of requests currently in the ready state (not yet
1248executed).
1249
1250=item IO::AIO::npending
1251
1252Returns the number of requests currently in the pending state (executed,
1253but not yet processed by poll_cb).
1254
1255=back
1256
940=cut 1257=cut
941 1258
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; 1259min_parallel 8;
959 1260
960END { 1261END { flush }
961 max_parallel 0;
962}
963 1262
9641; 12631;
965 1264
966=head2 FORK BEHAVIOUR 1265=head2 FORK BEHAVIOUR
967 1266
… …
987bytes of memory. In addition, stat requests need a stat buffer (possibly 1286bytes of memory. In addition, stat requests need a stat buffer (possibly
988a few hundred bytes), readdir requires a result buffer and so on. Perl 1287a few hundred bytes), readdir requires a result buffer and so on. Perl
989scalars and other data passed into aio requests will also be locked and 1288scalars and other data passed into aio requests will also be locked and
990will consume memory till the request has entered the done state. 1289will consume memory till the request has entered the done state.
991 1290
992This is now awfully much, so queuing lots of requests is not usually a 1291This is not awfully much, so queuing lots of requests is not usually a
993problem. 1292problem.
994 1293
995Per-thread usage: 1294Per-thread usage:
996 1295
997In the execution phase, some aio requests require more memory for 1296In the execution phase, some aio requests require more memory for

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