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Revision 1.108 by root, Fri Jun 1 13:25:50 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 = '2.4';
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);
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 max_outstanding nreqs); 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 aioreq_pri $pri 250=item $prev_pri = aioreq_pri [$pri]
181 251
182Sets the priority for the next aio request. The default priority 252Returns the priority value that would be used for the next request and, if
253C<$pri> is given, sets the priority for the next aio request.
254
183is C<0>, the minimum and maximum priorities are C<-4> and C<4>, 255The default priority is C<0>, the minimum and maximum priorities are C<-4>
184respectively. Requests with higher priority will be serviced first. 256and C<4>, respectively. Requests with higher priority will be serviced
257first.
185 258
186The priority will be reset to C<0> after each call to one of the C<aio_> 259The priority will be reset to C<0> after each call to one of the C<aio_*>
187functions. 260functions.
188 261
189Example: open a file with low priority, then read something from it with 262Example: open a file with low priority, then read something from it with
190higher priority so the read request is serviced before other low priority 263higher priority so the read request is serviced before other low priority
191open requests (potentially spamming the cache): 264open requests (potentially spamming the cache):
… …
198 aio_read $_[0], ..., sub { 271 aio_read $_[0], ..., sub {
199 ... 272 ...
200 }; 273 };
201 }; 274 };
202 275
276
203=item aioreq_nice $pri_adjust 277=item aioreq_nice $pri_adjust
204 278
205Similar 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
206priority, so effects are cumulative. 280priority, so the effect is cumulative.
281
207 282
208=item aio_open $pathname, $flags, $mode, $callback->($fh) 283=item aio_open $pathname, $flags, $mode, $callback->($fh)
209 284
210Asynchronously 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
211created filehandle for the file. 286created filehandle for the file.
… …
217list. They are the same as used by C<sysopen>. 292list. They are the same as used by C<sysopen>.
218 293
219Likewise, 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
220didn'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>,
221except 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,
222and C<0666> or C<0777> if you do). 297and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
298by the umask in effect then the request is being executed, so better never
299change the umask.
223 300
224Example: 301Example:
225 302
226 aio_open "/etc/passwd", O_RDONLY, 0, sub { 303 aio_open "/etc/passwd", O_RDONLY, 0, sub {
227 if ($_[0]) { 304 if ($_[0]) {
… …
230 } else { 307 } else {
231 die "open failed: $!\n"; 308 die "open failed: $!\n";
232 } 309 }
233 }; 310 };
234 311
312
235=item aio_close $fh, $callback->($status) 313=item aio_close $fh, $callback->($status)
236 314
237Asynchronously close a file and call the callback with the result 315Asynchronously close a file and call the callback with the result
238code. I<WARNING:> although accepted, you should not pass in a perl 316code. I<WARNING:> although accepted, you should not pass in a perl
239filehandle here, as perl will likely close the file descriptor another 317filehandle here, as perl will likely close the file descriptor another
… …
241C<close> or just let filehandles go out of scope. 319C<close> or just let filehandles go out of scope.
242 320
243This is supposed to be a bug in the API, so that might change. It's 321This is supposed to be a bug in the API, so that might change. It's
244therefore best to avoid this function. 322therefore best to avoid this function.
245 323
324
246=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 325=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
247 326
248=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 327=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
249 328
250Reads or writes C<length> bytes from the specified C<fh> and C<offset> 329Reads 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 330into 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 331callback without the actual number of bytes read (or -1 on error, just
253like the syscall). 332like the syscall). If C<offset> is undefined, then the current file offset
333will be used (and updated), otherwise the file offset will not be changed
334by these calls.
254 335
255The C<$data> scalar I<MUST NOT> be modified in any way while the request 336The C<$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 337is outstanding. Modifying it can result in segfaults or World War III (if
257necessary/optional hardware is installed). 338the necessary/optional hardware is installed).
258 339
259Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 340Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
260offset C<0> within the scalar: 341offset C<0> within the scalar:
261 342
262 aio_read $fh, 7, 15, $buffer, 0, sub { 343 aio_read $fh, 7, 15, $buffer, 0, sub {
263 $_[0] > 0 or die "read error: $!"; 344 $_[0] > 0 or die "read error: $!";
264 print "read $_[0] bytes: <$buffer>\n"; 345 print "read $_[0] bytes: <$buffer>\n";
265 }; 346 };
266 347
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}
334 348
335=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 349=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
336 350
337Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 351Tries 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 352reading 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 366C<$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 367bytes 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 368provides 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 369value equals C<$length> one can assume that C<$length> bytes have been
356read. 370read.
371
357 372
358=item aio_readahead $fh,$offset,$length, $callback->($retval) 373=item aio_readahead $fh,$offset,$length, $callback->($retval)
359 374
360C<aio_readahead> populates the page cache with data from a file so that 375C<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> 376subsequent 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. 382file. The current file offset of the file is left unchanged.
368 383
369If that syscall doesn't exist (likely if your OS isn't Linux) it will be 384If 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. 385emulated by simply reading the data, which would have a similar effect.
371 386
387
372=item aio_stat $fh_or_path, $callback->($status) 388=item aio_stat $fh_or_path, $callback->($status)
373 389
374=item aio_lstat $fh, $callback->($status) 390=item aio_lstat $fh, $callback->($status)
375 391
376Works like perl's C<stat> or C<lstat> in void context. The callback will 392Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
389 aio_stat "/etc/passwd", sub { 405 aio_stat "/etc/passwd", sub {
390 $_[0] and die "stat failed: $!"; 406 $_[0] and die "stat failed: $!";
391 print "size is ", -s _, "\n"; 407 print "size is ", -s _, "\n";
392 }; 408 };
393 409
410
411=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
412
413Works like perl's C<utime> function (including the special case of $atime
414and $mtime being undef). Fractional times are supported if the underlying
415syscalls support them.
416
417When called with a pathname, uses utimes(2) if available, otherwise
418utime(2). If called on a file descriptor, uses futimes(2) if available,
419otherwise returns ENOSYS, so this is not portable.
420
421Examples:
422
423 # set atime and mtime to current time (basically touch(1)):
424 aio_utime "path", undef, undef;
425 # set atime to current time and mtime to beginning of the epoch:
426 aio_utime "path", time, undef; # undef==0
427
428
429=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
430
431Works like perl's C<chown> function, except that C<undef> for either $uid
432or $gid is being interpreted as "do not change" (but -1 can also be used).
433
434Examples:
435
436 # same as "chown root path" in the shell:
437 aio_chown "path", 0, -1;
438 # same as above:
439 aio_chown "path", 0, undef;
440
441
442=item aio_chmod $fh_or_path, $mode, $callback->($status)
443
444Works like perl's C<chmod> function.
445
446
394=item aio_unlink $pathname, $callback->($status) 447=item aio_unlink $pathname, $callback->($status)
395 448
396Asynchronously unlink (delete) a file and call the callback with the 449Asynchronously unlink (delete) a file and call the callback with the
397result code. 450result code.
398 451
452
453=item aio_mknod $path, $mode, $dev, $callback->($status)
454
455[EXPERIMENTAL]
456
457Asynchronously create a device node (or fifo). See mknod(2).
458
459The only (POSIX-) portable way of calling this function is:
460
461 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
462
463
399=item aio_link $srcpath, $dstpath, $callback->($status) 464=item aio_link $srcpath, $dstpath, $callback->($status)
400 465
401Asynchronously create a new link to the existing object at C<$srcpath> at 466Asynchronously create a new link to the existing object at C<$srcpath> at
402the path C<$dstpath> and call the callback with the result code. 467the path C<$dstpath> and call the callback with the result code.
403 468
469
404=item aio_symlink $srcpath, $dstpath, $callback->($status) 470=item aio_symlink $srcpath, $dstpath, $callback->($status)
405 471
406Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 472Asynchronously 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. 473the path C<$dstpath> and call the callback with the result code.
408 474
475
476=item aio_readlink $path, $callback->($link)
477
478Asynchronously read the symlink specified by C<$path> and pass it to
479the callback. If an error occurs, nothing or undef gets passed to the
480callback.
481
482
409=item aio_rename $srcpath, $dstpath, $callback->($status) 483=item aio_rename $srcpath, $dstpath, $callback->($status)
410 484
411Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 485Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
412rename(2) and call the callback with the result code. 486rename(2) and call the callback with the result code.
413 487
488
489=item aio_mkdir $pathname, $mode, $callback->($status)
490
491Asynchronously mkdir (create) a directory and call the callback with
492the result code. C<$mode> will be modified by the umask at the time the
493request is executed, so do not change your umask.
494
495
414=item aio_rmdir $pathname, $callback->($status) 496=item aio_rmdir $pathname, $callback->($status)
415 497
416Asynchronously rmdir (delete) a directory and call the callback with the 498Asynchronously rmdir (delete) a directory and call the callback with the
417result code. 499result code.
500
418 501
419=item aio_readdir $pathname, $callback->($entries) 502=item aio_readdir $pathname, $callback->($entries)
420 503
421Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 504Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
422directory (i.e. opendir + readdir + closedir). The entries will not be 505directory (i.e. opendir + readdir + closedir). The entries will not be
423sorted, and will B<NOT> include the C<.> and C<..> entries. 506sorted, and will B<NOT> include the C<.> and C<..> entries.
424 507
425The callback a single argument which is either C<undef> or an array-ref 508The callback a single argument which is either C<undef> or an array-ref
426with the filenames. 509with the filenames.
427 510
511
512=item aio_load $path, $data, $callback->($status)
513
514This is a composite request that tries to fully load the given file into
515memory. Status is the same as with aio_read.
516
517=cut
518
519sub aio_load($$;$) {
520 aio_block {
521 my ($path, undef, $cb) = @_;
522 my $data = \$_[1];
523
524 my $pri = aioreq_pri;
525 my $grp = aio_group $cb;
526
527 aioreq_pri $pri;
528 add $grp aio_open $path, O_RDONLY, 0, sub {
529 my $fh = shift
530 or return $grp->result (-1);
531
532 aioreq_pri $pri;
533 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
534 $grp->result ($_[0]);
535 };
536 };
537
538 $grp
539 }
540}
541
542=item aio_copy $srcpath, $dstpath, $callback->($status)
543
544Try to copy the I<file> (directories not supported as either source or
545destination) from C<$srcpath> to C<$dstpath> and call the callback with
546the C<0> (error) or C<-1> ok.
547
548This is a composite request that it creates the destination file with
549mode 0200 and copies the contents of the source file into it using
550C<aio_sendfile>, followed by restoring atime, mtime, access mode and
551uid/gid, in that order.
552
553If an error occurs, the partial destination file will be unlinked, if
554possible, except when setting atime, mtime, access mode and uid/gid, where
555errors are being ignored.
556
557=cut
558
559sub aio_copy($$;$) {
560 aio_block {
561 my ($src, $dst, $cb) = @_;
562
563 my $pri = aioreq_pri;
564 my $grp = aio_group $cb;
565
566 aioreq_pri $pri;
567 add $grp aio_open $src, O_RDONLY, 0, sub {
568 if (my $src_fh = $_[0]) {
569 my @stat = stat $src_fh;
570
571 aioreq_pri $pri;
572 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
573 if (my $dst_fh = $_[0]) {
574 aioreq_pri $pri;
575 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
576 if ($_[0] == $stat[7]) {
577 $grp->result (0);
578 close $src_fh;
579
580 # those should not normally block. should. should.
581 utime $stat[8], $stat[9], $dst;
582 chmod $stat[2] & 07777, $dst_fh;
583 chown $stat[4], $stat[5], $dst_fh;
584 close $dst_fh;
585 } else {
586 $grp->result (-1);
587 close $src_fh;
588 close $dst_fh;
589
590 aioreq $pri;
591 add $grp aio_unlink $dst;
592 }
593 };
594 } else {
595 $grp->result (-1);
596 }
597 },
598
599 } else {
600 $grp->result (-1);
601 }
602 };
603
604 $grp
605 }
606}
607
608=item aio_move $srcpath, $dstpath, $callback->($status)
609
610Try to move the I<file> (directories not supported as either source or
611destination) from C<$srcpath> to C<$dstpath> and call the callback with
612the C<0> (error) or C<-1> ok.
613
614This is a composite request that tries to rename(2) the file first. If
615rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
616that is successful, unlinking the C<$srcpath>.
617
618=cut
619
620sub aio_move($$;$) {
621 aio_block {
622 my ($src, $dst, $cb) = @_;
623
624 my $pri = aioreq_pri;
625 my $grp = aio_group $cb;
626
627 aioreq_pri $pri;
628 add $grp aio_rename $src, $dst, sub {
629 if ($_[0] && $! == EXDEV) {
630 aioreq_pri $pri;
631 add $grp aio_copy $src, $dst, sub {
632 $grp->result ($_[0]);
633
634 if (!$_[0]) {
635 aioreq_pri $pri;
636 add $grp aio_unlink $src;
637 }
638 };
639 } else {
640 $grp->result ($_[0]);
641 }
642 };
643
644 $grp
645 }
646}
647
428=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 648=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429 649
430Scans a directory (similar to C<aio_readdir>) but additionally tries to 650Scans a directory (similar to C<aio_readdir>) but additionally tries to
431separate the entries of directory C<$path> into two sets of names, ones 651efficiently separate the entries of directory C<$path> into two sets of
432you can recurse into (directories or links to them), and ones you cannot 652names, directories you can recurse into (directories), and ones you cannot
433recurse into (everything else). 653recurse into (everything else, including symlinks to directories).
434 654
435C<aio_scandir> is a composite request that creates of many sub requests_ 655C<aio_scandir> is a composite request that creates of many sub requests_
436C<$maxreq> specifies the maximum number of outstanding aio requests that 656C<$maxreq> specifies the maximum number of outstanding aio requests that
437this function generates. If it is C<< <= 0 >>, then a suitable default 657this function generates. If it is C<< <= 0 >>, then a suitable default
438will be chosen (currently 6). 658will be chosen (currently 4).
439 659
440On error, the callback is called without arguments, otherwise it receives 660On error, the callback is called without arguments, otherwise it receives
441two array-refs with path-relative entry names. 661two array-refs with path-relative entry names.
442 662
443Example: 663Example:
… …
477as those tend to return 0 or 1 as link counts, which disables the 697as those tend to return 0 or 1 as link counts, which disables the
478directory counting heuristic. 698directory counting heuristic.
479 699
480=cut 700=cut
481 701
482sub aio_scandir($$$) { 702sub aio_scandir($$;$) {
703 aio_block {
483 my ($path, $maxreq, $cb) = @_; 704 my ($path, $maxreq, $cb) = @_;
484 705
706 my $pri = aioreq_pri;
707
485 my $grp = aio_group $cb; 708 my $grp = aio_group $cb;
486 709
487 $maxreq = 6 if $maxreq <= 0; 710 $maxreq = 4 if $maxreq <= 0;
488 711
489 # stat once 712 # stat once
713 aioreq_pri $pri;
490 add $grp aio_stat $path, sub { 714 add $grp aio_stat $path, sub {
491 return $grp->result () if $_[0]; 715 return $grp->result () if $_[0];
492 my $now = time; 716 my $now = time;
493 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 717 my $hash1 = join ":", (stat _)[0,1,3,7,9];
494 718
495 # read the directory entries 719 # read the directory entries
720 aioreq_pri $pri;
496 add $grp aio_readdir $path, sub { 721 add $grp aio_readdir $path, sub {
497 my $entries = shift 722 my $entries = shift
498 or return $grp->result (); 723 or return $grp->result ();
499 724
500 # stat the dir another time 725 # stat the dir another time
726 aioreq_pri $pri;
501 add $grp aio_stat $path, sub { 727 add $grp aio_stat $path, sub {
502 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 728 my $hash2 = join ":", (stat _)[0,1,3,7,9];
503 729
504 my $ndirs; 730 my $ndirs;
505 731
506 # take the slow route if anything looks fishy 732 # take the slow route if anything looks fishy
507 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 733 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508 $ndirs = -1; 734 $ndirs = -1;
509 } else { 735 } else {
510 # if nlink == 2, we are finished 736 # if nlink == 2, we are finished
511 # on non-posix-fs's, we rely on nlink < 2 737 # on non-posix-fs's, we rely on nlink < 2
512 $ndirs = (stat _)[3] - 2 738 $ndirs = (stat _)[3] - 2
513 or return $grp->result ([], $entries); 739 or return $grp->result ([], $entries);
514 } 740 }
515 741
516 # sort into likely dirs and likely nondirs 742 # sort into likely dirs and likely nondirs
517 # dirs == files without ".", short entries first 743 # dirs == files without ".", short entries first
518 $entries = [map $_->[0], 744 $entries = [map $_->[0],
519 sort { $b->[1] cmp $a->[1] } 745 sort { $b->[1] cmp $a->[1] }
520 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 746 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
521 @$entries]; 747 @$entries];
522 748
523 my (@dirs, @nondirs); 749 my (@dirs, @nondirs);
524 750
525 my $statgrp = add $grp aio_group sub { 751 my $statgrp = add $grp aio_group sub {
526 $grp->result (\@dirs, \@nondirs); 752 $grp->result (\@dirs, \@nondirs);
527 }; 753 };
528 754
529 limit $statgrp $maxreq; 755 limit $statgrp $maxreq;
530 feed $statgrp sub { 756 feed $statgrp sub {
531 return unless @$entries; 757 return unless @$entries;
532 my $entry = pop @$entries; 758 my $entry = pop @$entries;
533 759
760 aioreq_pri $pri;
534 add $statgrp aio_stat "$path/$entry/.", sub { 761 add $statgrp aio_stat "$path/$entry/.", sub {
535 if ($_[0] < 0) { 762 if ($_[0] < 0) {
536 push @nondirs, $entry; 763 push @nondirs, $entry;
537 } else { 764 } else {
538 # need to check for real directory 765 # need to check for real directory
766 aioreq_pri $pri;
539 add $statgrp aio_lstat "$path/$entry", sub { 767 add $statgrp aio_lstat "$path/$entry", sub {
540 if (-d _) { 768 if (-d _) {
541 push @dirs, $entry; 769 push @dirs, $entry;
542 770
543 if (!--$ndirs) { 771 unless (--$ndirs) {
544 push @nondirs, @$entries; 772 push @nondirs, @$entries;
545 $statgrp->cancel_subs; 773 feed $statgrp;
774 }
775 } else {
776 push @nondirs, $entry;
546 } 777 }
547 } else {
548 push @nondirs, $entry;
549 } 778 }
550 } 779 }
551 } 780 };
552 }; 781 };
553 }; 782 };
554 }; 783 };
555 }; 784 };
785
786 $grp
556 }; 787 }
788}
557 789
790=item aio_rmtree $path, $callback->($status)
791
792Delete a directory tree starting (and including) C<$path>, return the
793status of the final C<rmdir> only. This is a composite request that
794uses C<aio_scandir> to recurse into and rmdir directories, and unlink
795everything else.
796
797=cut
798
799sub aio_rmtree;
800sub aio_rmtree($;$) {
801 aio_block {
802 my ($path, $cb) = @_;
803
804 my $pri = aioreq_pri;
805 my $grp = aio_group $cb;
806
807 aioreq_pri $pri;
808 add $grp aio_scandir $path, 0, sub {
809 my ($dirs, $nondirs) = @_;
810
811 my $dirgrp = aio_group sub {
812 add $grp aio_rmdir $path, sub {
813 $grp->result ($_[0]);
814 };
815 };
816
817 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
818 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
819
820 add $grp $dirgrp;
821 };
822
558 $grp 823 $grp
824 }
559} 825}
560 826
561=item aio_fsync $fh, $callback->($status) 827=item aio_fsync $fh, $callback->($status)
562 828
563Asynchronously call fsync on the given filehandle and call the callback 829Asynchronously call fsync on the given filehandle and call the callback
… …
682=item * They can also can also be added to other IO::AIO::GRP objects. 948=item * They can also can also be added to other IO::AIO::GRP objects.
683 949
684=item * You must not add requests to a group from within the group callback (or 950=item * You must not add requests to a group from within the group callback (or
685any later time). 951any later time).
686 952
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 953=back
692 954
693Their lifetime, simplified, looks like this: when they are empty, they 955Their lifetime, simplified, looks like this: when they are empty, they
694will finish very quickly. If they contain only requests that are in the 956will finish very quickly. If they contain only requests that are in the
695C<done> state, they will also finish. Otherwise they will continue to 957C<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. 980itself. Useful when you queued a lot of events but got a result early.
719 981
720=item $grp->result (...) 982=item $grp->result (...)
721 983
722Set the result value(s) that will be passed to the group callback when all 984Set the result value(s) that will be passed to the group callback when all
723subrequests have finished. By default, no argument will be passed. 985subrequests have finished and set thre groups errno to the current value
986of errno (just like calling C<errno> without an error number). By default,
987no argument will be passed and errno is zero.
988
989=item $grp->errno ([$errno])
990
991Sets the group errno value to C<$errno>, or the current value of errno
992when the argument is missing.
993
994Every aio request has an associated errno value that is restored when
995the callback is invoked. This method lets you change this value from its
996default (0).
997
998Calling C<result> will also set errno, so make sure you either set C<$!>
999before the call to C<result>, or call c<errno> after it.
724 1000
725=item feed $grp $callback->($grp) 1001=item feed $grp $callback->($grp)
726 1002
727Sets a feeder/generator on this group: every group can have an attached 1003Sets a feeder/generator on this group: every group can have an attached
728generator that generates requests if idle. The idea behind this is that, 1004generator that generates requests if idle. The idea behind this is that,
… …
767 1043
768=back 1044=back
769 1045
770=head2 SUPPORT FUNCTIONS 1046=head2 SUPPORT FUNCTIONS
771 1047
1048=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1049
772=over 4 1050=over 4
773 1051
774=item $fileno = IO::AIO::poll_fileno 1052=item $fileno = IO::AIO::poll_fileno
775 1053
776Return the I<request result pipe file descriptor>. This filehandle must be 1054Return the I<request result pipe file descriptor>. This filehandle must be
… …
780 1058
781See C<poll_cb> for an example. 1059See C<poll_cb> for an example.
782 1060
783=item IO::AIO::poll_cb 1061=item IO::AIO::poll_cb
784 1062
785Process all outstanding events on the result pipe. You have to call this 1063Process some outstanding events on the result pipe. You have to call this
786regularly. Returns the number of events processed. Returns immediately 1064regularly. Returns the number of events processed. Returns immediately
787when no events are outstanding. 1065when no events are outstanding. The amount of events processed depends on
1066the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1067
1068If not all requests were processed for whatever reason, the filehandle
1069will still be ready when C<poll_cb> returns.
788 1070
789Example: Install an Event watcher that automatically calls 1071Example: Install an Event watcher that automatically calls
790IO::AIO::poll_cb with high priority: 1072IO::AIO::poll_cb with high priority:
791 1073
792 Event->io (fd => IO::AIO::poll_fileno, 1074 Event->io (fd => IO::AIO::poll_fileno,
793 poll => 'r', async => 1, 1075 poll => 'r', async => 1,
794 cb => \&IO::AIO::poll_cb); 1076 cb => \&IO::AIO::poll_cb);
795 1077
1078=item IO::AIO::max_poll_reqs $nreqs
1079
1080=item IO::AIO::max_poll_time $seconds
1081
1082These set the maximum number of requests (default C<0>, meaning infinity)
1083that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1084the maximum amount of time (default C<0>, meaning infinity) spent in
1085C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1086of time C<poll_cb> is allowed to use).
1087
1088Setting C<max_poll_time> to a non-zero value creates an overhead of one
1089syscall per request processed, which is not normally a problem unless your
1090callbacks are really really fast or your OS is really really slow (I am
1091not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1092
1093Setting these is useful if you want to ensure some level of
1094interactiveness when perl is not fast enough to process all requests in
1095time.
1096
1097For interactive programs, values such as C<0.01> to C<0.1> should be fine.
1098
1099Example: Install an Event watcher that automatically calls
1100IO::AIO::poll_cb with low priority, to ensure that other parts of the
1101program get the CPU sometimes even under high AIO load.
1102
1103 # try not to spend much more than 0.1s in poll_cb
1104 IO::AIO::max_poll_time 0.1;
1105
1106 # use a low priority so other tasks have priority
1107 Event->io (fd => IO::AIO::poll_fileno,
1108 poll => 'r', nice => 1,
1109 cb => &IO::AIO::poll_cb);
1110
796=item IO::AIO::poll_wait 1111=item IO::AIO::poll_wait
797 1112
1113If there are any outstanding requests and none of them in the result
798Wait till the result filehandle becomes ready for reading (simply does a 1114phase, wait till the result filehandle becomes ready for reading (simply
799C<select> on the filehandle. This is useful if you want to synchronously wait 1115does a C<select> on the filehandle. This is useful if you want to
800for some requests to finish). 1116synchronously wait for some requests to finish).
801 1117
802See C<nreqs> for an example. 1118See C<nreqs> for an example.
803 1119
1120=item IO::AIO::poll
1121
1122Waits until some requests have been handled.
1123
1124Returns the number of requests processed, but is otherwise strictly
1125equivalent to:
1126
1127 IO::AIO::poll_wait, IO::AIO::poll_cb
1128
804=item IO::AIO::nreqs 1129=item IO::AIO::flush
805 1130
806Returns the number of requests currently outstanding (i.e. for which their 1131Wait till all outstanding AIO requests have been handled.
807callback has not been invoked yet).
808 1132
809Example: wait till there are no outstanding requests anymore: 1133Strictly equivalent to:
810 1134
811 IO::AIO::poll_wait, IO::AIO::poll_cb 1135 IO::AIO::poll_wait, IO::AIO::poll_cb
812 while IO::AIO::nreqs; 1136 while IO::AIO::nreqs;
813 1137
814=item IO::AIO::flush 1138=back
815 1139
816Wait till all outstanding AIO requests have been handled. 1140=head3 CONTROLLING THE NUMBER OF THREADS
817 1141
818Strictly equivalent to: 1142=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 1143
832=item IO::AIO::min_parallel $nthreads 1144=item IO::AIO::min_parallel $nthreads
833 1145
834Set the minimum number of AIO threads to C<$nthreads>. The current 1146Set the minimum number of AIO threads to C<$nthreads>. The current
835default is C<8>, which means eight asynchronous operations can execute 1147default is C<8>, which means eight asynchronous operations can execute
836concurrently at any one time (the number of outstanding requests, 1148concurrently at any one time (the number of outstanding requests,
837however, is unlimited). 1149however, is unlimited).
838 1150
839IO::AIO starts threads only on demand, when an AIO request is queued and 1151IO::AIO starts threads only on demand, when an AIO request is queued and
840no free thread exists. 1152no free thread exists. Please note that queueing up a hundred requests can
1153create demand for a hundred threads, even if it turns out that everything
1154is in the cache and could have been processed faster by a single thread.
841 1155
842It is recommended to keep the number of threads relatively low, as some 1156It is recommended to keep the number of threads relatively low, as some
843Linux kernel versions will scale negatively with the number of threads 1157Linux kernel versions will scale negatively with the number of threads
844(higher parallelity => MUCH higher latency). With current Linux 2.6 1158(higher parallelity => MUCH higher latency). With current Linux 2.6
845versions, 4-32 threads should be fine. 1159versions, 4-32 threads should be fine.
… …
859This module automatically runs C<max_parallel 0> at program end, to ensure 1173This module automatically runs C<max_parallel 0> at program end, to ensure
860that all threads are killed and that there are no outstanding requests. 1174that all threads are killed and that there are no outstanding requests.
861 1175
862Under normal circumstances you don't need to call this function. 1176Under normal circumstances you don't need to call this function.
863 1177
1178=item IO::AIO::max_idle $nthreads
1179
1180Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1181threads that did not get a request to process within 10 seconds). That
1182means if a thread becomes idle while C<$nthreads> other threads are also
1183idle, it will free its resources and exit.
1184
1185This is useful when you allow a large number of threads (e.g. 100 or 1000)
1186to allow for extremely high load situations, but want to free resources
1187under normal circumstances (1000 threads can easily consume 30MB of RAM).
1188
1189The default is probably ok in most situations, especially if thread
1190creation is fast. If thread creation is very slow on your system you might
1191want to use larger values.
1192
864=item $oldnreqs = IO::AIO::max_outstanding $nreqs 1193=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
865 1194
866[DEPRECATED] 1195This is a very bad function to use in interactive programs because it
1196blocks, and a bad way to reduce concurrency because it is inexact: Better
1197use an C<aio_group> together with a feed callback.
867 1198
868Sets the maximum number of outstanding requests to C<$nreqs>. If you 1199Sets the maximum number of outstanding requests to C<$nreqs>. If you
869try to queue up more than this number of requests, the caller will block until 1200to queue up more than this number of requests, the next call to the
870some requests have been handled. 1201C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1202function will block until the limit is no longer exceeded.
871 1203
872The default is very large, so normally there is no practical limit. If you 1204The default value is very large, so there is no practical limit on the
873queue up many requests in a loop it often improves speed if you set 1205number of outstanding requests.
874this to a relatively low number, such as C<100>.
875 1206
876This function does not work well together with C<aio_group>'s, and their 1207You can still queue as many requests as you want. Therefore,
877feeder interface is better suited to limiting concurrency, so do not use 1208C<max_oustsanding> is mainly useful in simple scripts (with low values) or
878this function. 1209as a stop gap to shield against fatal memory overflow (with large values).
879 1210
880Under normal circumstances you don't need to call this function. 1211=back
1212
1213=head3 STATISTICAL INFORMATION
1214
1215=over
1216
1217=item IO::AIO::nreqs
1218
1219Returns the number of requests currently in the ready, execute or pending
1220states (i.e. for which their callback has not been invoked yet).
1221
1222Example: wait till there are no outstanding requests anymore:
1223
1224 IO::AIO::poll_wait, IO::AIO::poll_cb
1225 while IO::AIO::nreqs;
1226
1227=item IO::AIO::nready
1228
1229Returns the number of requests currently in the ready state (not yet
1230executed).
1231
1232=item IO::AIO::npending
1233
1234Returns the number of requests currently in the pending state (executed,
1235but not yet processed by poll_cb).
881 1236
882=back 1237=back
883 1238
884=cut 1239=cut
885 1240
… …
899 *$sym 1254 *$sym
900} 1255}
901 1256
902min_parallel 8; 1257min_parallel 8;
903 1258
904END { 1259END { flush }
905 max_parallel 0;
906}
907 1260
9081; 12611;
909 1262
910=head2 FORK BEHAVIOUR 1263=head2 FORK BEHAVIOUR
911 1264

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