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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.78 by root, Thu Oct 26 12:38:04 2006 UTC vs.
Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC

… …
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
9 aio_open "/etc/passwd", O_RDONLY, 0, sub { 9 aio_open "/etc/passwd", O_RDONLY, 0, sub {
10 my ($fh) = @_; 10 my $fh = shift
11 or die "/etc/passwd: $!";
11 ... 12 ...
12 }; 13 };
13 14
14 aio_unlink "/tmp/file", sub { }; 15 aio_unlink "/tmp/file", sub { };
15 16
… …
25 $req->cancel; # cancel request if still in queue 26 $req->cancel; # cancel request if still in queue
26 27
27 my $grp = aio_group sub { print "all stats done\n" }; 28 my $grp = aio_group sub { print "all stats done\n" };
28 add $grp aio_stat "..." for ...; 29 add $grp aio_stat "..." for ...;
29 30
31 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32 use AnyEvent::AIO;
33
30 # AnyEvent integration 34 # EV integration
31 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; 35 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
32 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33 36
34 # Event integration 37 # Event integration
35 Event->io (fd => IO::AIO::poll_fileno, 38 Event->io (fd => IO::AIO::poll_fileno,
36 poll => 'r', 39 poll => 'r',
37 cb => \&IO::AIO::poll_cb); 40 cb => \&IO::AIO::poll_cb);
… …
49 \&IO::AIO::poll_cb); 52 \&IO::AIO::poll_cb);
50 53
51=head1 DESCRIPTION 54=head1 DESCRIPTION
52 55
53This module implements asynchronous I/O using whatever means your 56This module implements asynchronous I/O using whatever means your
54operating system supports. 57operating system supports. It is implemented as an interface to C<libeio>
58(L<http://software.schmorp.de/pkg/libeio.html>).
59
60Asynchronous means that operations that can normally block your program
61(e.g. reading from disk) will be done asynchronously: the operation
62will still block, but you can do something else in the meantime. This
63is extremely useful for programs that need to stay interactive even
64when doing heavy I/O (GUI programs, high performance network servers
65etc.), but can also be used to easily do operations in parallel that are
66normally done sequentially, e.g. stat'ing many files, which is much faster
67on a RAID volume or over NFS when you do a number of stat operations
68concurrently.
69
70While most of this works on all types of file descriptors (for
71example sockets), using these functions on file descriptors that
72support nonblocking operation (again, sockets, pipes etc.) is
73very inefficient. Use an event loop for that (such as the L<EV>
74module): IO::AIO will naturally fit into such an event loop itself.
55 75
56In this version, a number of threads are started that execute your 76In this version, a number of threads are started that execute your
57requests and signal their completion. You don't need thread support 77requests and signal their completion. You don't need thread support
58in perl, and the threads created by this module will not be visible 78in perl, and the threads created by this module will not be visible
59to perl. In the future, this module might make use of the native aio 79to perl. In the future, this module might make use of the native aio
60functions available on many operating systems. However, they are often 80functions available on many operating systems. However, they are often
61not well-supported or restricted (Linux doesn't allow them on normal 81not well-supported or restricted (GNU/Linux doesn't allow them on normal
62files currently, for example), and they would only support aio_read and 82files currently, for example), and they would only support aio_read and
63aio_write, so the remaining functionality would have to be implemented 83aio_write, so the remaining functionality would have to be implemented
64using threads anyway. 84using threads anyway.
65 85
66Although the module will work with in the presence of other (Perl-) 86Although the module will work in the presence of other (Perl-) threads,
67threads, it is currently not reentrant in any way, so use appropriate 87it is currently not reentrant in any way, so use appropriate locking
68locking yourself, always call C<poll_cb> from within the same thread, or 88yourself, always call C<poll_cb> from within the same thread, or never
69never call C<poll_cb> (or other C<aio_> functions) recursively. 89call C<poll_cb> (or other C<aio_> functions) recursively.
90
91=head2 EXAMPLE
92
93This is a simple example that uses the EV module and loads
94F</etc/passwd> asynchronously:
95
96 use Fcntl;
97 use EV;
98 use IO::AIO;
99
100 # register the IO::AIO callback with EV
101 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
102
103 # queue the request to open /etc/passwd
104 aio_open "/etc/passwd", O_RDONLY, 0, sub {
105 my $fh = shift
106 or die "error while opening: $!";
107
108 # stat'ing filehandles is generally non-blocking
109 my $size = -s $fh;
110
111 # queue a request to read the file
112 my $contents;
113 aio_read $fh, 0, $size, $contents, 0, sub {
114 $_[0] == $size
115 or die "short read: $!";
116
117 close $fh;
118
119 # file contents now in $contents
120 print $contents;
121
122 # exit event loop and program
123 EV::unloop;
124 };
125 };
126
127 # possibly queue up other requests, or open GUI windows,
128 # check for sockets etc. etc.
129
130 # process events as long as there are some:
131 EV::loop;
70 132
71=head1 REQUEST ANATOMY AND LIFETIME 133=head1 REQUEST ANATOMY AND LIFETIME
72 134
73Every C<aio_*> function creates a request. which is a C data structure not 135Every C<aio_*> function creates a request. which is a C data structure not
74directly visible to Perl. 136directly visible to Perl.
… …
116Request has reached the end of its lifetime and holds no resources anymore 178Request 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 179(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 180aio request is severed and calling its methods will either do nothing or
119result in a runtime error). 181result in a runtime error).
120 182
183=back
184
121=cut 185=cut
122 186
123package IO::AIO; 187package IO::AIO;
188
189use Carp ();
124 190
125no warnings; 191no warnings;
126use strict 'vars'; 192use strict 'vars';
127 193
128use base 'Exporter'; 194use base 'Exporter';
129 195
130BEGIN { 196BEGIN {
131 our $VERSION = '2.0'; 197 our $VERSION = '3.23';
132 198
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 199 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
134 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 200 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
135 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move 201 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
136 aio_group aio_nop); 202 aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
203 aio_rename aio_link aio_move aio_copy aio_group
204 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
205 aio_chmod aio_utime aio_truncate);
206
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 207 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 208 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel nreqs); 209 min_parallel max_parallel max_idle
210 nreqs nready npending nthreads
211 max_poll_time max_poll_reqs);
212
213 push @AIO_REQ, qw(aio_busy); # not exported
140 214
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 215 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 216
143 require XSLoader; 217 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 218 XSLoader::load ("IO::AIO", $VERSION);
145} 219}
146 220
147=head1 FUNCTIONS 221=head1 FUNCTIONS
148 222
149=head2 AIO FUNCTIONS 223=head2 AIO REQUEST FUNCTIONS
150 224
151All the C<aio_*> calls are more or less thin wrappers around the syscall 225All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 226with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 227and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 228which must be a code reference. This code reference will get called with
155the syscall return code (e.g. most syscalls return C<-1> on error, unlike 229the syscall return code (e.g. most syscalls return C<-1> on error, unlike
156perl, which usually delivers "false") as it's sole argument when the given 230perl, which usually delivers "false") as its sole argument after the given
157syscall has been executed asynchronously. 231syscall has been executed asynchronously.
158 232
159All functions expecting a filehandle keep a copy of the filehandle 233All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 234internally until the request has finished.
161 235
162All requests return objects of type L<IO::AIO::REQ> that allow further 236All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 237further manipulation of those requests while they are in-flight.
164 238
165The pathnames you pass to these routines I<must> be absolute and 239The pathnames you pass to these routines I<must> be absolute and
166encoded in byte form. The reason for the former is that at the time the 240encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 241request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 242changed. Alternatively, you can make sure that you never change the
169current working directory. 243current working directory anywhere in the program and then use relative
244paths.
170 245
171To encode pathnames to byte form, either make sure you either: a) 246To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 247in filenames you got from outside (command line, readdir etc.) without
173etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode 248tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174your pathnames to the locale (or other) encoding in effect in the user 249your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 250environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 251use something else to ensure your scalar has the correct contents.
252
253This works, btw. independent of the internal UTF-8 bit, which IO::AIO
254handles correctly whether it is set or not.
177 255
178=over 4 256=over 4
179 257
180=item aioreq_pri $pri 258=item $prev_pri = aioreq_pri [$pri]
181 259
182Sets the priority for the next aio request. The default priority 260Returns the priority value that would be used for the next request and, if
261C<$pri> is given, sets the priority for the next aio request.
262
183is C<0>, the minimum and maximum priorities are C<-4> and C<4>, 263The default priority is C<0>, the minimum and maximum priorities are C<-4>
184respectively. Requests with higher priority will be serviced first. 264and C<4>, respectively. Requests with higher priority will be serviced
265first.
185 266
186The priority will be reset to C<0> after each call to one of the C<aio_> 267The priority will be reset to C<0> after each call to one of the C<aio_*>
187functions. 268functions.
188 269
189Example: open a file with low priority, then read something from it with 270Example: open a file with low priority, then read something from it with
190higher priority so the read request is serviced before other low priority 271higher priority so the read request is serviced before other low priority
191open requests (potentially spamming the cache): 272open requests (potentially spamming the cache):
… …
198 aio_read $_[0], ..., sub { 279 aio_read $_[0], ..., sub {
199 ... 280 ...
200 }; 281 };
201 }; 282 };
202 283
284
203=item aioreq_nice $pri_adjust 285=item aioreq_nice $pri_adjust
204 286
205Similar to C<aioreq_pri>, but subtracts the given value from the current 287Similar to C<aioreq_pri>, but subtracts the given value from the current
206priority, so effects are cumulative. 288priority, so the effect is cumulative.
289
207 290
208=item aio_open $pathname, $flags, $mode, $callback->($fh) 291=item aio_open $pathname, $flags, $mode, $callback->($fh)
209 292
210Asynchronously open or create a file and call the callback with a newly 293Asynchronously open or create a file and call the callback with a newly
211created filehandle for the file. 294created filehandle for the file.
… …
217list. They are the same as used by C<sysopen>. 300list. They are the same as used by C<sysopen>.
218 301
219Likewise, C<$mode> specifies the mode of the newly created file, if it 302Likewise, C<$mode> specifies the mode of the newly created file, if it
220didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, 303didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
221except that it is mandatory (i.e. use C<0> if you don't create new files, 304except that it is mandatory (i.e. use C<0> if you don't create new files,
222and C<0666> or C<0777> if you do). 305and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
306by the umask in effect then the request is being executed, so better never
307change the umask.
223 308
224Example: 309Example:
225 310
226 aio_open "/etc/passwd", O_RDONLY, 0, sub { 311 aio_open "/etc/passwd", O_RDONLY, 0, sub {
227 if ($_[0]) { 312 if ($_[0]) {
… …
230 } else { 315 } else {
231 die "open failed: $!\n"; 316 die "open failed: $!\n";
232 } 317 }
233 }; 318 };
234 319
320
235=item aio_close $fh, $callback->($status) 321=item aio_close $fh, $callback->($status)
236 322
237Asynchronously close a file and call the callback with the result 323Asynchronously close a file and call the callback with the result
238code. I<WARNING:> although accepted, you should not pass in a perl 324code.
239filehandle here, as perl will likely close the file descriptor another
240time when the filehandle is destroyed. Normally, you can safely call perls
241C<close> or just let filehandles go out of scope.
242 325
243This is supposed to be a bug in the API, so that might change. It's 326Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
244therefore best to avoid this function. 327closing the file descriptor associated with the filehandle itself.
328
329Therefore, C<aio_close> will not close the filehandle - instead it will
330use dup2 to overwrite the file descriptor with the write-end of a pipe
331(the pipe fd will be created on demand and will be cached).
332
333Or in other words: the file descriptor will be closed, but it will not be
334free for reuse until the perl filehandle is closed.
335
336=cut
245 337
246=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 338=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
247 339
248=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 340=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
249 341
250Reads or writes C<length> bytes from the specified C<fh> and C<offset> 342Reads or writes C<$length> bytes from or to the specified C<$fh> and
251into the scalar given by C<data> and offset C<dataoffset> and calls the 343C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
252callback without the actual number of bytes read (or -1 on error, just 344and calls the callback without the actual number of bytes read (or -1 on
253like the syscall). 345error, just like the syscall).
346
347C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
348offset plus the actual number of bytes read.
349
350If C<$offset> is undefined, then the current file descriptor offset will
351be used (and updated), otherwise the file descriptor offset will not be
352changed by these calls.
353
354If C<$length> is undefined in C<aio_write>, use the remaining length of
355C<$data>.
356
357If C<$dataoffset> is less than zero, it will be counted from the end of
358C<$data>.
254 359
255The C<$data> scalar I<MUST NOT> be modified in any way while the request 360The C<$data> scalar I<MUST NOT> be modified in any way while the request
256is outstanding. Modifying it can result in segfaults or WW3 (if the 361is outstanding. Modifying it can result in segfaults or World War III (if
257necessary/optional hardware is installed). 362the necessary/optional hardware is installed).
258 363
259Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 364Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
260offset C<0> within the scalar: 365offset C<0> within the scalar:
261 366
262 aio_read $fh, 7, 15, $buffer, 0, sub { 367 aio_read $fh, 7, 15, $buffer, 0, sub {
263 $_[0] > 0 or die "read error: $!"; 368 $_[0] > 0 or die "read error: $!";
264 print "read $_[0] bytes: <$buffer>\n"; 369 print "read $_[0] bytes: <$buffer>\n";
265 }; 370 };
266 371
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}
334 372
335=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 373=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
336 374
337Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 375Tries 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 376reading 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 390C<$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 391bytes 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 392provides 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 393value equals C<$length> one can assume that C<$length> bytes have been
356read. 394read.
395
357 396
358=item aio_readahead $fh,$offset,$length, $callback->($retval) 397=item aio_readahead $fh,$offset,$length, $callback->($retval)
359 398
360C<aio_readahead> populates the page cache with data from a file so that 399C<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> 400subsequent 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. 406file. The current file offset of the file is left unchanged.
368 407
369If that syscall doesn't exist (likely if your OS isn't Linux) it will be 408If 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. 409emulated by simply reading the data, which would have a similar effect.
371 410
411
372=item aio_stat $fh_or_path, $callback->($status) 412=item aio_stat $fh_or_path, $callback->($status)
373 413
374=item aio_lstat $fh, $callback->($status) 414=item aio_lstat $fh, $callback->($status)
375 415
376Works like perl's C<stat> or C<lstat> in void context. The callback will 416Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
389 aio_stat "/etc/passwd", sub { 429 aio_stat "/etc/passwd", sub {
390 $_[0] and die "stat failed: $!"; 430 $_[0] and die "stat failed: $!";
391 print "size is ", -s _, "\n"; 431 print "size is ", -s _, "\n";
392 }; 432 };
393 433
434
435=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
436
437Works like perl's C<utime> function (including the special case of $atime
438and $mtime being undef). Fractional times are supported if the underlying
439syscalls support them.
440
441When called with a pathname, uses utimes(2) if available, otherwise
442utime(2). If called on a file descriptor, uses futimes(2) if available,
443otherwise returns ENOSYS, so this is not portable.
444
445Examples:
446
447 # set atime and mtime to current time (basically touch(1)):
448 aio_utime "path", undef, undef;
449 # set atime to current time and mtime to beginning of the epoch:
450 aio_utime "path", time, undef; # undef==0
451
452
453=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
454
455Works like perl's C<chown> function, except that C<undef> for either $uid
456or $gid is being interpreted as "do not change" (but -1 can also be used).
457
458Examples:
459
460 # same as "chown root path" in the shell:
461 aio_chown "path", 0, -1;
462 # same as above:
463 aio_chown "path", 0, undef;
464
465
466=item aio_truncate $fh_or_path, $offset, $callback->($status)
467
468Works like truncate(2) or ftruncate(2).
469
470
471=item aio_chmod $fh_or_path, $mode, $callback->($status)
472
473Works like perl's C<chmod> function.
474
475
394=item aio_unlink $pathname, $callback->($status) 476=item aio_unlink $pathname, $callback->($status)
395 477
396Asynchronously unlink (delete) a file and call the callback with the 478Asynchronously unlink (delete) a file and call the callback with the
397result code. 479result code.
398 480
481
482=item aio_mknod $path, $mode, $dev, $callback->($status)
483
484[EXPERIMENTAL]
485
486Asynchronously create a device node (or fifo). See mknod(2).
487
488The only (POSIX-) portable way of calling this function is:
489
490 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
491
492
399=item aio_link $srcpath, $dstpath, $callback->($status) 493=item aio_link $srcpath, $dstpath, $callback->($status)
400 494
401Asynchronously create a new link to the existing object at C<$srcpath> at 495Asynchronously create a new link to the existing object at C<$srcpath> at
402the path C<$dstpath> and call the callback with the result code. 496the path C<$dstpath> and call the callback with the result code.
403 497
498
404=item aio_symlink $srcpath, $dstpath, $callback->($status) 499=item aio_symlink $srcpath, $dstpath, $callback->($status)
405 500
406Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 501Asynchronously 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. 502the path C<$dstpath> and call the callback with the result code.
408 503
504
505=item aio_readlink $path, $callback->($link)
506
507Asynchronously read the symlink specified by C<$path> and pass it to
508the callback. If an error occurs, nothing or undef gets passed to the
509callback.
510
511
409=item aio_rename $srcpath, $dstpath, $callback->($status) 512=item aio_rename $srcpath, $dstpath, $callback->($status)
410 513
411Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 514Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
412rename(2) and call the callback with the result code. 515rename(2) and call the callback with the result code.
413 516
517
518=item aio_mkdir $pathname, $mode, $callback->($status)
519
520Asynchronously mkdir (create) a directory and call the callback with
521the result code. C<$mode> will be modified by the umask at the time the
522request is executed, so do not change your umask.
523
524
414=item aio_rmdir $pathname, $callback->($status) 525=item aio_rmdir $pathname, $callback->($status)
415 526
416Asynchronously rmdir (delete) a directory and call the callback with the 527Asynchronously rmdir (delete) a directory and call the callback with the
417result code. 528result code.
529
418 530
419=item aio_readdir $pathname, $callback->($entries) 531=item aio_readdir $pathname, $callback->($entries)
420 532
421Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 533Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
422directory (i.e. opendir + readdir + closedir). The entries will not be 534directory (i.e. opendir + readdir + closedir). The entries will not be
423sorted, and will B<NOT> include the C<.> and C<..> entries. 535sorted, and will B<NOT> include the C<.> and C<..> entries.
424 536
425The callback a single argument which is either C<undef> or an array-ref 537The callback is passed a single argument which is either C<undef> or an
426with the filenames. 538array-ref with the filenames.
539
540
541=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
542
543Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
544behaviour and output format. In case of an error, C<$entries> will be
545C<undef>.
546
547The flags are a combination of the following constants, ORed together (the
548flags will also be passed to the callback, possibly modified):
549
550=over 4
551
552=item IO::AIO::READDIR_DENTS
553
554When this flag is off, then the callback gets an arrayref with of names
555only (as with C<aio_readdir>), otherwise it gets an arrayref with
556C<[$name, $type, $inode]> arrayrefs, each describing a single directory
557entry in more detail.
558
559C<$name> is the name of the entry.
560
561C<$type> is one of the C<IO::AIO::DT_xxx> constants:
562
563C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
564C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
565C<IO::AIO::DT_WHT>.
566
567C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
568know, you have to run stat yourself. Also, for speed reasons, the C<$type>
569scalars are read-only: you can not modify them.
570
571C<$inode> is the inode number (which might not be exact on systems with 64
572bit inode numbers and 32 bit perls). This field has unspecified content on
573systems that do not deliver the inode information.
574
575=item IO::AIO::READDIR_DIRS_FIRST
576
577When this flag is set, then the names will be returned in an order where
578likely directories come first. This is useful when you need to quickly
579find directories, or you want to find all directories while avoiding to
580stat() each entry.
581
582If the system returns type information in readdir, then this is used
583to find directories directly. Otherwise, likely directories are files
584beginning with ".", or otherwise files with no dots, of which files with
585short names are tried first.
586
587=item IO::AIO::READDIR_STAT_ORDER
588
589When this flag is set, then the names will be returned in an order
590suitable for stat()'ing each one. That is, when you plan to stat()
591all files in the given directory, then the returned order will likely
592be fastest.
593
594If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
595the likely dirs come first, resulting in a less optimal stat order.
596
597=item IO::AIO::READDIR_FOUND_UNKNOWN
598
599This flag should not be set when calling C<aio_readdirx>. Instead, it
600is being set by C<aio_readdirx>, when any of the C<$type>'s found were
601C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
602C<$type>'s are known, which can be used to speed up some algorithms.
603
604=back
605
606
607=item aio_load $path, $data, $callback->($status)
608
609This is a composite request that tries to fully load the given file into
610memory. Status is the same as with aio_read.
611
612=cut
613
614sub aio_load($$;$) {
615 my ($path, undef, $cb) = @_;
616 my $data = \$_[1];
617
618 my $pri = aioreq_pri;
619 my $grp = aio_group $cb;
620
621 aioreq_pri $pri;
622 add $grp aio_open $path, O_RDONLY, 0, sub {
623 my $fh = shift
624 or return $grp->result (-1);
625
626 aioreq_pri $pri;
627 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
628 $grp->result ($_[0]);
629 };
630 };
631
632 $grp
633}
634
635=item aio_copy $srcpath, $dstpath, $callback->($status)
636
637Try to copy the I<file> (directories not supported as either source or
638destination) from C<$srcpath> to C<$dstpath> and call the callback with
639the C<0> (error) or C<-1> ok.
640
641This is a composite request that creates the destination file with
642mode 0200 and copies the contents of the source file into it using
643C<aio_sendfile>, followed by restoring atime, mtime, access mode and
644uid/gid, in that order.
645
646If an error occurs, the partial destination file will be unlinked, if
647possible, except when setting atime, mtime, access mode and uid/gid, where
648errors are being ignored.
649
650=cut
651
652sub aio_copy($$;$) {
653 my ($src, $dst, $cb) = @_;
654
655 my $pri = aioreq_pri;
656 my $grp = aio_group $cb;
657
658 aioreq_pri $pri;
659 add $grp aio_open $src, O_RDONLY, 0, sub {
660 if (my $src_fh = $_[0]) {
661 my @stat = stat $src_fh; # hmm, might bock over nfs?
662
663 aioreq_pri $pri;
664 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
665 if (my $dst_fh = $_[0]) {
666 aioreq_pri $pri;
667 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
668 if ($_[0] == $stat[7]) {
669 $grp->result (0);
670 close $src_fh;
671
672 my $ch = sub {
673 aioreq_pri $pri;
674 add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
675 aioreq_pri $pri;
676 add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
677 aioreq_pri $pri;
678 add $grp aio_close $dst_fh;
679 }
680 };
681 };
682
683 aioreq_pri $pri;
684 add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
685 if ($_[0] < 0 && $! == ENOSYS) {
686 aioreq_pri $pri;
687 add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
688 } else {
689 $ch->();
690 }
691 };
692 } else {
693 $grp->result (-1);
694 close $src_fh;
695 close $dst_fh;
696
697 aioreq $pri;
698 add $grp aio_unlink $dst;
699 }
700 };
701 } else {
702 $grp->result (-1);
703 }
704 },
705
706 } else {
707 $grp->result (-1);
708 }
709 };
710
711 $grp
712}
713
714=item aio_move $srcpath, $dstpath, $callback->($status)
715
716Try to move the I<file> (directories not supported as either source or
717destination) from C<$srcpath> to C<$dstpath> and call the callback with
718the C<0> (error) or C<-1> ok.
719
720This is a composite request that tries to rename(2) the file first; if
721rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
722that is successful, unlinks the C<$srcpath>.
723
724=cut
725
726sub aio_move($$;$) {
727 my ($src, $dst, $cb) = @_;
728
729 my $pri = aioreq_pri;
730 my $grp = aio_group $cb;
731
732 aioreq_pri $pri;
733 add $grp aio_rename $src, $dst, sub {
734 if ($_[0] && $! == EXDEV) {
735 aioreq_pri $pri;
736 add $grp aio_copy $src, $dst, sub {
737 $grp->result ($_[0]);
738
739 if (!$_[0]) {
740 aioreq_pri $pri;
741 add $grp aio_unlink $src;
742 }
743 };
744 } else {
745 $grp->result ($_[0]);
746 }
747 };
748
749 $grp
750}
427 751
428=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 752=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429 753
430Scans a directory (similar to C<aio_readdir>) but additionally tries to 754Scans a directory (similar to C<aio_readdir>) but additionally tries to
431efficiently separate the entries of directory C<$path> into two sets of 755efficiently separate the entries of directory C<$path> into two sets of
… …
433recurse into (everything else, including symlinks to directories). 757recurse into (everything else, including symlinks to directories).
434 758
435C<aio_scandir> is a composite request that creates of many sub requests_ 759C<aio_scandir> is a composite request that creates of many sub requests_
436C<$maxreq> specifies the maximum number of outstanding aio requests that 760C<$maxreq> specifies the maximum number of outstanding aio requests that
437this function generates. If it is C<< <= 0 >>, then a suitable default 761this function generates. If it is C<< <= 0 >>, then a suitable default
438will be chosen (currently 6). 762will be chosen (currently 4).
439 763
440On error, the callback is called without arguments, otherwise it receives 764On error, the callback is called without arguments, otherwise it receives
441two array-refs with path-relative entry names. 765two array-refs with path-relative entry names.
442 766
443Example: 767Example:
… …
450 774
451Implementation notes. 775Implementation notes.
452 776
453The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. 777The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
454 778
779If readdir returns file type information, then this is used directly to
780find directories.
781
455After reading the directory, the modification time, size etc. of the 782Otherwise, after reading the directory, the modification time, size etc.
456directory before and after the readdir is checked, and if they match (and 783of the directory before and after the readdir is checked, and if they
457isn't the current time), the link count will be used to decide how many 784match (and isn't the current time), the link count will be used to decide
458entries are directories (if >= 2). Otherwise, no knowledge of the number 785how many entries are directories (if >= 2). Otherwise, no knowledge of the
459of subdirectories will be assumed. 786number of subdirectories will be assumed.
460 787
461Then entries will be sorted into likely directories (everything without 788Then entries will be sorted into likely directories a non-initial dot
462a non-initial dot currently) and likely non-directories (everything 789currently) and likely non-directories (see C<aio_readdirx>). Then every
463else). Then every entry plus an appended C</.> will be C<stat>'ed, 790entry plus an appended C</.> will be C<stat>'ed, likely directories first,
464likely directories first. If that succeeds, it assumes that the entry 791in order of their inode numbers. If that succeeds, it assumes that the
465is a directory or a symlink to directory (which will be checked 792entry is a directory or a symlink to directory (which will be checked
466seperately). This is often faster than stat'ing the entry itself because 793seperately). This is often faster than stat'ing the entry itself because
467filesystems might detect the type of the entry without reading the inode 794filesystems might detect the type of the entry without reading the inode
468data (e.g. ext2fs filetype feature). 795data (e.g. ext2fs filetype feature), even on systems that cannot return
796the filetype information on readdir.
469 797
470If the known number of directories (link count - 2) has been reached, the 798If the known number of directories (link count - 2) has been reached, the
471rest of the entries is assumed to be non-directories. 799rest of the entries is assumed to be non-directories.
472 800
473This only works with certainty on POSIX (= UNIX) filesystems, which 801This only works with certainty on POSIX (= UNIX) filesystems, which
… …
477as those tend to return 0 or 1 as link counts, which disables the 805as those tend to return 0 or 1 as link counts, which disables the
478directory counting heuristic. 806directory counting heuristic.
479 807
480=cut 808=cut
481 809
482sub aio_scandir($$$) { 810sub aio_scandir($$;$) {
483 my ($path, $maxreq, $cb) = @_; 811 my ($path, $maxreq, $cb) = @_;
484 812
813 my $pri = aioreq_pri;
814
485 my $grp = aio_group $cb; 815 my $grp = aio_group $cb;
486 816
487 $maxreq = 6 if $maxreq <= 0; 817 $maxreq = 4 if $maxreq <= 0;
488 818
489 # stat once 819 # stat once
820 aioreq_pri $pri;
490 add $grp aio_stat $path, sub { 821 add $grp aio_stat $path, sub {
491 return $grp->result () if $_[0]; 822 return $grp->result () if $_[0];
492 my $now = time; 823 my $now = time;
493 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 824 my $hash1 = join ":", (stat _)[0,1,3,7,9];
494 825
495 # read the directory entries 826 # read the directory entries
827 aioreq_pri $pri;
496 add $grp aio_readdir $path, sub { 828 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
497 my $entries = shift 829 my $entries = shift
498 or return $grp->result (); 830 or return $grp->result ();
499 831
500 # stat the dir another time 832 # stat the dir another time
833 aioreq_pri $pri;
501 add $grp aio_stat $path, sub { 834 add $grp aio_stat $path, sub {
502 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 835 my $hash2 = join ":", (stat _)[0,1,3,7,9];
503 836
504 my $ndirs; 837 my $ndirs;
505 838
506 # take the slow route if anything looks fishy 839 # take the slow route if anything looks fishy
507 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 840 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508 $ndirs = -1; 841 $ndirs = -1;
509 } else { 842 } else {
510 # if nlink == 2, we are finished 843 # if nlink == 2, we are finished
511 # on non-posix-fs's, we rely on nlink < 2 844 # for non-posix-fs's, we rely on nlink < 2
512 $ndirs = (stat _)[3] - 2 845 $ndirs = (stat _)[3] - 2
513 or return $grp->result ([], $entries); 846 or return $grp->result ([], $entries);
514 } 847 }
515 848
516 # sort into likely dirs and likely nondirs
517 # dirs == files without ".", short entries first
518 $entries = [map $_->[0],
519 sort { $b->[1] cmp $a->[1] }
520 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
521 @$entries];
522
523 my (@dirs, @nondirs); 849 my (@dirs, @nondirs);
524 850
525 my $statgrp = add $grp aio_group sub { 851 my $statgrp = add $grp aio_group sub {
526 $grp->result (\@dirs, \@nondirs); 852 $grp->result (\@dirs, \@nondirs);
527 }; 853 };
528 854
529 limit $statgrp $maxreq; 855 limit $statgrp $maxreq;
530 feed $statgrp sub { 856 feed $statgrp sub {
531 return unless @$entries; 857 return unless @$entries;
532 my $entry = pop @$entries; 858 my $entry = shift @$entries;
533 859
860 aioreq_pri $pri;
534 add $statgrp aio_stat "$path/$entry/.", sub { 861 add $statgrp aio_stat "$path/$entry/.", sub {
535 if ($_[0] < 0) { 862 if ($_[0] < 0) {
536 push @nondirs, $entry; 863 push @nondirs, $entry;
537 } else { 864 } else {
538 # need to check for real directory 865 # need to check for real directory
866 aioreq_pri $pri;
539 add $statgrp aio_lstat "$path/$entry", sub { 867 add $statgrp aio_lstat "$path/$entry", sub {
540 if (-d _) { 868 if (-d _) {
541 push @dirs, $entry; 869 push @dirs, $entry;
542 870
543 unless (--$ndirs) { 871 unless (--$ndirs) {
… …
556 }; 884 };
557 885
558 $grp 886 $grp
559} 887}
560 888
889=item aio_rmtree $path, $callback->($status)
890
891Delete a directory tree starting (and including) C<$path>, return the
892status of the final C<rmdir> only. This is a composite request that
893uses C<aio_scandir> to recurse into and rmdir directories, and unlink
894everything else.
895
896=cut
897
898sub aio_rmtree;
899sub aio_rmtree($;$) {
900 my ($path, $cb) = @_;
901
902 my $pri = aioreq_pri;
903 my $grp = aio_group $cb;
904
905 aioreq_pri $pri;
906 add $grp aio_scandir $path, 0, sub {
907 my ($dirs, $nondirs) = @_;
908
909 my $dirgrp = aio_group sub {
910 add $grp aio_rmdir $path, sub {
911 $grp->result ($_[0]);
912 };
913 };
914
915 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
916 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
917
918 add $grp $dirgrp;
919 };
920
921 $grp
922}
923
924=item aio_sync $callback->($status)
925
926Asynchronously call sync and call the callback when finished.
927
561=item aio_fsync $fh, $callback->($status) 928=item aio_fsync $fh, $callback->($status)
562 929
563Asynchronously call fsync on the given filehandle and call the callback 930Asynchronously call fsync on the given filehandle and call the callback
564with the fsync result code. 931with the fsync result code.
565 932
… …
568Asynchronously call fdatasync on the given filehandle and call the 935Asynchronously call fdatasync on the given filehandle and call the
569callback with the fdatasync result code. 936callback with the fdatasync result code.
570 937
571If this call isn't available because your OS lacks it or it couldn't be 938If this call isn't available because your OS lacks it or it couldn't be
572detected, it will be emulated by calling C<fsync> instead. 939detected, it will be emulated by calling C<fsync> instead.
940
941=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
942
943Sync the data portion of the file specified by C<$offset> and C<$length>
944to disk (but NOT the metadata), by calling the Linux-specific
945sync_file_range call. If sync_file_range is not available or it returns
946ENOSYS, then fdatasync or fsync is being substituted.
947
948C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
949C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
950C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
951manpage for details.
952
953=item aio_pathsync $path, $callback->($status)
954
955This request tries to open, fsync and close the given path. This is a
956composite request intended to sync directories after directory operations
957(E.g. rename). This might not work on all operating systems or have any
958specific effect, but usually it makes sure that directory changes get
959written to disc. It works for anything that can be opened for read-only,
960not just directories.
961
962Passes C<0> when everything went ok, and C<-1> on error.
963
964=cut
965
966sub aio_pathsync($;$) {
967 my ($path, $cb) = @_;
968
969 my $pri = aioreq_pri;
970 my $grp = aio_group $cb;
971
972 aioreq_pri $pri;
973 add $grp aio_open $path, O_RDONLY, 0, sub {
974 my ($fh) = @_;
975 if ($fh) {
976 aioreq_pri $pri;
977 add $grp aio_fsync $fh, sub {
978 $grp->result ($_[0]);
979
980 aioreq_pri $pri;
981 add $grp aio_close $fh;
982 };
983 } else {
984 $grp->result (-1);
985 }
986 };
987
988 $grp
989}
573 990
574=item aio_group $callback->(...) 991=item aio_group $callback->(...)
575 992
576This is a very special aio request: Instead of doing something, it is a 993This is a very special aio request: Instead of doing something, it is a
577container for other aio requests, which is useful if you want to bundle 994container for other aio requests, which is useful if you want to bundle
… …
627=item cancel $req 1044=item cancel $req
628 1045
629Cancels the request, if possible. Has the effect of skipping execution 1046Cancels the request, if possible. Has the effect of skipping execution
630when entering the B<execute> state and skipping calling the callback when 1047when entering the B<execute> state and skipping calling the callback when
631entering the the B<result> state, but will leave the request otherwise 1048entering the the B<result> state, but will leave the request otherwise
632untouched. That means that requests that currently execute will not be 1049untouched (with the exception of readdir). That means that requests that
633stopped and resources held by the request will not be freed prematurely. 1050currently execute will not be stopped and resources held by the request
1051will not be freed prematurely.
634 1052
635=item cb $req $callback->(...) 1053=item cb $req $callback->(...)
636 1054
637Replace (or simply set) the callback registered to the request. 1055Replace (or simply set) the callback registered to the request.
638 1056
… …
689Their lifetime, simplified, looks like this: when they are empty, they 1107Their lifetime, simplified, looks like this: when they are empty, they
690will finish very quickly. If they contain only requests that are in the 1108will finish very quickly. If they contain only requests that are in the
691C<done> state, they will also finish. Otherwise they will continue to 1109C<done> state, they will also finish. Otherwise they will continue to
692exist. 1110exist.
693 1111
694That means after creating a group you have some time to add requests. And 1112That means after creating a group you have some time to add requests
695in the callbacks of those requests, you can add further requests to the 1113(precisely before the callback has been invoked, which is only done within
696group. And only when all those requests have finished will the the group 1114the C<poll_cb>). And in the callbacks of those requests, you can add
697itself finish. 1115further requests to the group. And only when all those requests have
1116finished will the the group itself finish.
698 1117
699=over 4 1118=over 4
700 1119
701=item add $grp ... 1120=item add $grp ...
702 1121
… …
714itself. Useful when you queued a lot of events but got a result early. 1133itself. Useful when you queued a lot of events but got a result early.
715 1134
716=item $grp->result (...) 1135=item $grp->result (...)
717 1136
718Set the result value(s) that will be passed to the group callback when all 1137Set the result value(s) that will be passed to the group callback when all
719subrequests have finished. By default, no argument will be passed. 1138subrequests have finished and set the groups errno to the current value
1139of errno (just like calling C<errno> without an error number). By default,
1140no argument will be passed and errno is zero.
1141
1142=item $grp->errno ([$errno])
1143
1144Sets the group errno value to C<$errno>, or the current value of errno
1145when the argument is missing.
1146
1147Every aio request has an associated errno value that is restored when
1148the callback is invoked. This method lets you change this value from its
1149default (0).
1150
1151Calling C<result> will also set errno, so make sure you either set C<$!>
1152before the call to C<result>, or call c<errno> after it.
720 1153
721=item feed $grp $callback->($grp) 1154=item feed $grp $callback->($grp)
722 1155
723Sets a feeder/generator on this group: every group can have an attached 1156Sets a feeder/generator on this group: every group can have an attached
724generator that generates requests if idle. The idea behind this is that, 1157generator that generates requests if idle. The idea behind this is that,
725although you could just queue as many requests as you want in a group, 1158although you could just queue as many requests as you want in a group,
726this might starve other requests for a potentially long time. For 1159this might starve other requests for a potentially long time. For example,
727example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> 1160C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
728requests, delaying any later requests for a long time. 1161delaying any later requests for a long time.
729 1162
730To avoid this, and allow incremental generation of requests, you can 1163To avoid this, and allow incremental generation of requests, you can
731instead a group and set a feeder on it that generates those requests. The 1164instead a group and set a feeder on it that generates those requests. The
732feed callback will be called whenever there are few enough (see C<limit>, 1165feed callback will be called whenever there are few enough (see C<limit>,
733below) requests active in the group itself and is expected to queue more 1166below) requests active in the group itself and is expected to queue more
… …
737not impose any limits). 1170not impose any limits).
738 1171
739If the feed does not queue more requests when called, it will be 1172If the feed does not queue more requests when called, it will be
740automatically removed from the group. 1173automatically removed from the group.
741 1174
742If the feed limit is C<0>, it will be set to C<2> automatically. 1175If the feed limit is C<0> when this method is called, it will be set to
1176C<2> automatically.
743 1177
744Example: 1178Example:
745 1179
746 # stat all files in @files, but only ever use four aio requests concurrently: 1180 # stat all files in @files, but only ever use four aio requests concurrently:
747 1181
… …
759Sets the feeder limit for the group: The feeder will be called whenever 1193Sets the feeder limit for the group: The feeder will be called whenever
760the group contains less than this many requests. 1194the group contains less than this many requests.
761 1195
762Setting the limit to C<0> will pause the feeding process. 1196Setting the limit to C<0> will pause the feeding process.
763 1197
1198The default value for the limit is C<0>, but note that setting a feeder
1199automatically bumps it up to C<2>.
1200
764=back 1201=back
765 1202
766=head2 SUPPORT FUNCTIONS 1203=head2 SUPPORT FUNCTIONS
767 1204
1205=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1206
768=over 4 1207=over 4
769 1208
770=item $fileno = IO::AIO::poll_fileno 1209=item $fileno = IO::AIO::poll_fileno
771 1210
772Return the I<request result pipe file descriptor>. This filehandle must be 1211Return the I<request result pipe file descriptor>. This filehandle must be
773polled for reading by some mechanism outside this module (e.g. Event or 1212polled for reading by some mechanism outside this module (e.g. EV, Glib,
774select, see below or the SYNOPSIS). If the pipe becomes readable you have 1213select and so on, see below or the SYNOPSIS). If the pipe becomes readable
775to call C<poll_cb> to check the results. 1214you have to call C<poll_cb> to check the results.
776 1215
777See C<poll_cb> for an example. 1216See C<poll_cb> for an example.
778 1217
779=item IO::AIO::poll_cb 1218=item IO::AIO::poll_cb
780 1219
781Process all outstanding events on the result pipe. You have to call this 1220Process some outstanding events on the result pipe. You have to call this
782regularly. Returns the number of events processed. Returns immediately 1221regularly. Returns C<0> if all events could be processed, or C<-1> if it
783when no events are outstanding. 1222returned earlier for whatever reason. Returns immediately when no events
1223are outstanding. The amount of events processed depends on the settings of
1224C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
784 1225
785If not all requests were processed for whatever reason, the filehandle 1226If not all requests were processed for whatever reason, the filehandle
786will still be ready when C<poll_cb> returns. 1227will still be ready when C<poll_cb> returns, so normally you don't have to
1228do anything special to have it called later.
787 1229
788Example: Install an Event watcher that automatically calls 1230Example: Install an Event watcher that automatically calls
789IO::AIO::poll_cb with high priority: 1231IO::AIO::poll_cb with high priority (more examples can be found in the
1232SYNOPSIS section, at the top of this document):
790 1233
791 Event->io (fd => IO::AIO::poll_fileno, 1234 Event->io (fd => IO::AIO::poll_fileno,
792 poll => 'r', async => 1, 1235 poll => 'r', async => 1,
793 cb => \&IO::AIO::poll_cb); 1236 cb => \&IO::AIO::poll_cb);
794 1237
795=item IO::AIO::poll_some $max_requests 1238=item IO::AIO::max_poll_reqs $nreqs
796 1239
797Similar to C<poll_cb>, but only processes up to C<$max_requests> requests 1240=item IO::AIO::max_poll_time $seconds
798at a time.
799 1241
800Useful if you want to ensure some level of interactiveness when perl is 1242These set the maximum number of requests (default C<0>, meaning infinity)
801not fast enough to process all requests in time. 1243that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1244the maximum amount of time (default C<0>, meaning infinity) spent in
1245C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1246of time C<poll_cb> is allowed to use).
1247
1248Setting C<max_poll_time> to a non-zero value creates an overhead of one
1249syscall per request processed, which is not normally a problem unless your
1250callbacks are really really fast or your OS is really really slow (I am
1251not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1252
1253Setting these is useful if you want to ensure some level of
1254interactiveness when perl is not fast enough to process all requests in
1255time.
1256
1257For interactive programs, values such as C<0.01> to C<0.1> should be fine.
802 1258
803Example: Install an Event watcher that automatically calls 1259Example: Install an Event watcher that automatically calls
804IO::AIO::poll_some with low priority, to ensure that other parts of the 1260IO::AIO::poll_cb with low priority, to ensure that other parts of the
805program get the CPU sometimes even under high AIO load. 1261program get the CPU sometimes even under high AIO load.
806 1262
1263 # try not to spend much more than 0.1s in poll_cb
1264 IO::AIO::max_poll_time 0.1;
1265
1266 # use a low priority so other tasks have priority
807 Event->io (fd => IO::AIO::poll_fileno, 1267 Event->io (fd => IO::AIO::poll_fileno,
808 poll => 'r', nice => 1, 1268 poll => 'r', nice => 1,
809 cb => sub { IO::AIO::poll_some 256 }); 1269 cb => &IO::AIO::poll_cb);
810 1270
811=item IO::AIO::poll_wait 1271=item IO::AIO::poll_wait
812 1272
1273If there are any outstanding requests and none of them in the result
813Wait till the result filehandle becomes ready for reading (simply does a 1274phase, wait till the result filehandle becomes ready for reading (simply
814C<select> on the filehandle. This is useful if you want to synchronously wait 1275does a C<select> on the filehandle. This is useful if you want to
815for some requests to finish). 1276synchronously wait for some requests to finish).
816 1277
817See C<nreqs> for an example. 1278See C<nreqs> for an example.
818 1279
1280=item IO::AIO::poll
1281
1282Waits until some requests have been handled.
1283
1284Returns the number of requests processed, but is otherwise strictly
1285equivalent to:
1286
1287 IO::AIO::poll_wait, IO::AIO::poll_cb
1288
819=item IO::AIO::nreqs 1289=item IO::AIO::flush
820 1290
821Returns the number of requests currently outstanding (i.e. for which their 1291Wait till all outstanding AIO requests have been handled.
822callback has not been invoked yet).
823 1292
824Example: wait till there are no outstanding requests anymore: 1293Strictly equivalent to:
825 1294
826 IO::AIO::poll_wait, IO::AIO::poll_cb 1295 IO::AIO::poll_wait, IO::AIO::poll_cb
827 while IO::AIO::nreqs; 1296 while IO::AIO::nreqs;
828 1297
829=item IO::AIO::flush 1298=back
830 1299
831Wait till all outstanding AIO requests have been handled. 1300=head3 CONTROLLING THE NUMBER OF THREADS
832 1301
833Strictly equivalent to: 1302=over
834
835 IO::AIO::poll_wait, IO::AIO::poll_cb
836 while IO::AIO::nreqs;
837
838=item IO::AIO::poll
839
840Waits until some requests have been handled.
841
842Strictly equivalent to:
843
844 IO::AIO::poll_wait, IO::AIO::poll_cb
845 if IO::AIO::nreqs;
846 1303
847=item IO::AIO::min_parallel $nthreads 1304=item IO::AIO::min_parallel $nthreads
848 1305
849Set the minimum number of AIO threads to C<$nthreads>. The current 1306Set the minimum number of AIO threads to C<$nthreads>. The current
850default is C<8>, which means eight asynchronous operations can execute 1307default is C<8>, which means eight asynchronous operations can execute
851concurrently at any one time (the number of outstanding requests, 1308concurrently at any one time (the number of outstanding requests,
852however, is unlimited). 1309however, is unlimited).
853 1310
854IO::AIO starts threads only on demand, when an AIO request is queued and 1311IO::AIO starts threads only on demand, when an AIO request is queued and
855no free thread exists. 1312no free thread exists. Please note that queueing up a hundred requests can
1313create demand for a hundred threads, even if it turns out that everything
1314is in the cache and could have been processed faster by a single thread.
856 1315
857It is recommended to keep the number of threads relatively low, as some 1316It is recommended to keep the number of threads relatively low, as some
858Linux kernel versions will scale negatively with the number of threads 1317Linux kernel versions will scale negatively with the number of threads
859(higher parallelity => MUCH higher latency). With current Linux 2.6 1318(higher parallelity => MUCH higher latency). With current Linux 2.6
860versions, 4-32 threads should be fine. 1319versions, 4-32 threads should be fine.
… …
874This module automatically runs C<max_parallel 0> at program end, to ensure 1333This module automatically runs C<max_parallel 0> at program end, to ensure
875that all threads are killed and that there are no outstanding requests. 1334that all threads are killed and that there are no outstanding requests.
876 1335
877Under normal circumstances you don't need to call this function. 1336Under normal circumstances you don't need to call this function.
878 1337
1338=item IO::AIO::max_idle $nthreads
1339
1340Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1341threads that did not get a request to process within 10 seconds). That
1342means if a thread becomes idle while C<$nthreads> other threads are also
1343idle, it will free its resources and exit.
1344
1345This is useful when you allow a large number of threads (e.g. 100 or 1000)
1346to allow for extremely high load situations, but want to free resources
1347under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348
1349The default is probably ok in most situations, especially if thread
1350creation is fast. If thread creation is very slow on your system you might
1351want to use larger values.
1352
879=item $oldnreqs = IO::AIO::max_outstanding $nreqs 1353=item IO::AIO::max_outstanding $maxreqs
880 1354
881[REMOVED] 1355This is a very bad function to use in interactive programs because it
1356blocks, and a bad way to reduce concurrency because it is inexact: Better
1357use an C<aio_group> together with a feed callback.
882 1358
883Pre-2.x versions used max_outstanding for a crude request queue length limit.
884
885In 2.x+ you are advised to use a group and a feeder to limit
886concurrency. The max_outstanding feature ran very unstable (endless
887recursions causing segfaults, bad interaction with groups etc.) and was
888removed.
889
890I am deeply sorry, but I am still on the hunt for a good limiting interface.
891
892Original description was as follows:
893
894Sets the maximum number of outstanding requests to C<$nreqs>. If you try 1359Sets the maximum number of outstanding requests to C<$nreqs>. If you
895to queue up more than this number of requests, the caller will block until 1360do queue up more than this number of requests, the next call to the
896some requests have been handled. 1361C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1362function will block until the limit is no longer exceeded.
1363
1364The default value is very large, so there is no practical limit on the
1365number of outstanding requests.
1366
1367You can still queue as many requests as you want. Therefore,
1368C<max_outstanding> is mainly useful in simple scripts (with low values) or
1369as a stop gap to shield against fatal memory overflow (with large values).
897 1370
898=back 1371=back
899 1372
1373=head3 STATISTICAL INFORMATION
1374
1375=over
1376
1377=item IO::AIO::nreqs
1378
1379Returns the number of requests currently in the ready, execute or pending
1380states (i.e. for which their callback has not been invoked yet).
1381
1382Example: wait till there are no outstanding requests anymore:
1383
1384 IO::AIO::poll_wait, IO::AIO::poll_cb
1385 while IO::AIO::nreqs;
1386
1387=item IO::AIO::nready
1388
1389Returns the number of requests currently in the ready state (not yet
1390executed).
1391
1392=item IO::AIO::npending
1393
1394Returns the number of requests currently in the pending state (executed,
1395but not yet processed by poll_cb).
1396
1397=back
1398
900=cut 1399=cut
901 1400
902# support function to convert a fd into a perl filehandle
903sub _fd2fh {
904 return undef if $_[0] < 0;
905
906 # try to generate nice filehandles
907 my $sym = "IO::AIO::fd#$_[0]";
908 local *$sym;
909
910 open *$sym, "+<&=$_[0]" # usually works under any unix
911 or open *$sym, "<&=$_[0]" # cygwin needs this
912 or open *$sym, ">&=$_[0]" # or this
913 or return undef;
914
915 *$sym
916}
917
918min_parallel 8; 1401min_parallel 8;
919 1402
920END { 1403END { flush }
921 max_parallel 0;
922}
923 1404
9241; 14051;
925 1406
926=head2 FORK BEHAVIOUR 1407=head2 FORK BEHAVIOUR
927 1408
… …
947bytes of memory. In addition, stat requests need a stat buffer (possibly 1428bytes of memory. In addition, stat requests need a stat buffer (possibly
948a few hundred bytes), readdir requires a result buffer and so on. Perl 1429a few hundred bytes), readdir requires a result buffer and so on. Perl
949scalars and other data passed into aio requests will also be locked and 1430scalars and other data passed into aio requests will also be locked and
950will consume memory till the request has entered the done state. 1431will consume memory till the request has entered the done state.
951 1432
952This is now awfully much, so queuing lots of requests is not usually a 1433This is not awfully much, so queuing lots of requests is not usually a
953problem. 1434problem.
954 1435
955Per-thread usage: 1436Per-thread usage:
956 1437
957In the execution phase, some aio requests require more memory for 1438In the execution phase, some aio requests require more memory for
… …
962 1443
963Known bugs will be fixed in the next release. 1444Known bugs will be fixed in the next release.
964 1445
965=head1 SEE ALSO 1446=head1 SEE ALSO
966 1447
967L<Coro::AIO>. 1448L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1449more natural syntax.
968 1450
969=head1 AUTHOR 1451=head1 AUTHOR
970 1452
971 Marc Lehmann <schmorp@schmorp.de> 1453 Marc Lehmann <schmorp@schmorp.de>
972 http://home.schmorp.de/ 1454 http://home.schmorp.de/

Diff Legend

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