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Revision 1.77 by root, Wed Oct 25 17:57:30 2006 UTC vs.
Revision 1.160 by root, Wed Jul 1 08:12:18 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 = '3.261';
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 sendfile fadvise);
213
214 push @AIO_REQ, qw(aio_busy); # not exported
140 215
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 216 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 217
143 require XSLoader; 218 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 219 XSLoader::load ("IO::AIO", $VERSION);
145} 220}
146 221
147=head1 FUNCTIONS 222=head1 FUNCTIONS
148 223
149=head2 AIO FUNCTIONS 224=head2 AIO REQUEST FUNCTIONS
150 225
151All the C<aio_*> calls are more or less thin wrappers around the syscall 226All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 227with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 228and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 229which 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 230the 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 231perl, which usually delivers "false") as its sole argument after the given
157syscall has been executed asynchronously. 232syscall has been executed asynchronously.
158 233
159All functions expecting a filehandle keep a copy of the filehandle 234All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 235internally until the request has finished.
161 236
162All requests return objects of type L<IO::AIO::REQ> that allow further 237All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 238further manipulation of those requests while they are in-flight.
164 239
165The pathnames you pass to these routines I<must> be absolute and 240The 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 241encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 242request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 243changed. Alternatively, you can make sure that you never change the
169current working directory. 244current working directory anywhere in the program and then use relative
245paths.
170 246
171To encode pathnames to byte form, either make sure you either: a) 247To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 248in 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 249tinkering, 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 250your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 251environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 252use something else to ensure your scalar has the correct contents.
253
254This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255handles correctly whether it is set or not.
177 256
178=over 4 257=over 4
179 258
180=item aioreq_pri $pri 259=item $prev_pri = aioreq_pri [$pri]
181 260
182Sets the priority for the next aio request. The default priority 261Returns the priority value that would be used for the next request and, if
262C<$pri> is given, sets the priority for the next aio request.
263
183is C<0>, the minimum and maximum priorities are C<-4> and C<4>, 264The default priority is C<0>, the minimum and maximum priorities are C<-4>
184respectively. Requests with higher priority will be serviced first. 265and C<4>, respectively. Requests with higher priority will be serviced
266first.
185 267
186The priority will be reset to C<0> after each call to one of the C<aio_> 268The priority will be reset to C<0> after each call to one of the C<aio_*>
187functions. 269functions.
188 270
189Example: open a file with low priority, then read something from it with 271Example: open a file with low priority, then read something from it with
190higher priority so the read request is serviced before other low priority 272higher priority so the read request is serviced before other low priority
191open requests (potentially spamming the cache): 273open requests (potentially spamming the cache):
… …
198 aio_read $_[0], ..., sub { 280 aio_read $_[0], ..., sub {
199 ... 281 ...
200 }; 282 };
201 }; 283 };
202 284
285
203=item aioreq_nice $pri_adjust 286=item aioreq_nice $pri_adjust
204 287
205Similar to C<aioreq_pri>, but subtracts the given value from the current 288Similar to C<aioreq_pri>, but subtracts the given value from the current
206priority, so effects are cumulative. 289priority, so the effect is cumulative.
290
207 291
208=item aio_open $pathname, $flags, $mode, $callback->($fh) 292=item aio_open $pathname, $flags, $mode, $callback->($fh)
209 293
210Asynchronously open or create a file and call the callback with a newly 294Asynchronously open or create a file and call the callback with a newly
211created filehandle for the file. 295created filehandle for the file.
… …
217list. They are the same as used by C<sysopen>. 301list. They are the same as used by C<sysopen>.
218 302
219Likewise, C<$mode> specifies the mode of the newly created file, if it 303Likewise, C<$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>, 304didn'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, 305except 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). 306and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
307by the umask in effect then the request is being executed, so better never
308change the umask.
223 309
224Example: 310Example:
225 311
226 aio_open "/etc/passwd", O_RDONLY, 0, sub { 312 aio_open "/etc/passwd", O_RDONLY, 0, sub {
227 if ($_[0]) { 313 if ($_[0]) {
… …
230 } else { 316 } else {
231 die "open failed: $!\n"; 317 die "open failed: $!\n";
232 } 318 }
233 }; 319 };
234 320
321
235=item aio_close $fh, $callback->($status) 322=item aio_close $fh, $callback->($status)
236 323
237Asynchronously close a file and call the callback with the result 324Asynchronously close a file and call the callback with the result
238code. I<WARNING:> although accepted, you should not pass in a perl 325code.
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.
242 326
243This is supposed to be a bug in the API, so that might change. It's 327Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
244therefore best to avoid this function. 328closing the file descriptor associated with the filehandle itself.
329
330Therefore, C<aio_close> will not close the filehandle - instead it will
331use dup2 to overwrite the file descriptor with the write-end of a pipe
332(the pipe fd will be created on demand and will be cached).
333
334Or in other words: the file descriptor will be closed, but it will not be
335free for reuse until the perl filehandle is closed.
336
337=cut
245 338
246=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 339=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
247 340
248=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 341=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
249 342
250Reads or writes C<length> bytes from the specified C<fh> and C<offset> 343Reads 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 344C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
252callback without the actual number of bytes read (or -1 on error, just 345and calls the callback without the actual number of bytes read (or -1 on
253like the syscall). 346error, just like the syscall).
347
348C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
349offset plus the actual number of bytes read.
350
351If C<$offset> is undefined, then the current file descriptor offset will
352be used (and updated), otherwise the file descriptor offset will not be
353changed by these calls.
354
355If C<$length> is undefined in C<aio_write>, use the remaining length of
356C<$data>.
357
358If C<$dataoffset> is less than zero, it will be counted from the end of
359C<$data>.
254 360
255The C<$data> scalar I<MUST NOT> be modified in any way while the request 361The C<$data> scalar I<MUST NOT> be modified in any way while the request
256is outstanding. Modifying it can result in segfaults or WW3 (if the 362is outstanding. Modifying it can result in segfaults or World War III (if
257necessary/optional hardware is installed). 363the necessary/optional hardware is installed).
258 364
259Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 365Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
260offset C<0> within the scalar: 366offset C<0> within the scalar:
261 367
262 aio_read $fh, 7, 15, $buffer, 0, sub { 368 aio_read $fh, 7, 15, $buffer, 0, sub {
263 $_[0] > 0 or die "read error: $!"; 369 $_[0] > 0 or die "read error: $!";
264 print "read $_[0] bytes: <$buffer>\n"; 370 print "read $_[0] bytes: <$buffer>\n";
265 }; 371 };
266 372
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}
334 373
335=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 374=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
336 375
337Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 376Tries 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 377reading 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 391C<$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 392bytes 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 393provides 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 394value equals C<$length> one can assume that C<$length> bytes have been
356read. 395read.
396
357 397
358=item aio_readahead $fh,$offset,$length, $callback->($retval) 398=item aio_readahead $fh,$offset,$length, $callback->($retval)
359 399
360C<aio_readahead> populates the page cache with data from a file so that 400C<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> 401subsequent 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. 407file. The current file offset of the file is left unchanged.
368 408
369If that syscall doesn't exist (likely if your OS isn't Linux) it will be 409If 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. 410emulated by simply reading the data, which would have a similar effect.
371 411
412
372=item aio_stat $fh_or_path, $callback->($status) 413=item aio_stat $fh_or_path, $callback->($status)
373 414
374=item aio_lstat $fh, $callback->($status) 415=item aio_lstat $fh, $callback->($status)
375 416
376Works like perl's C<stat> or C<lstat> in void context. The callback will 417Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
389 aio_stat "/etc/passwd", sub { 430 aio_stat "/etc/passwd", sub {
390 $_[0] and die "stat failed: $!"; 431 $_[0] and die "stat failed: $!";
391 print "size is ", -s _, "\n"; 432 print "size is ", -s _, "\n";
392 }; 433 };
393 434
435
436=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437
438Works like perl's C<utime> function (including the special case of $atime
439and $mtime being undef). Fractional times are supported if the underlying
440syscalls support them.
441
442When called with a pathname, uses utimes(2) if available, otherwise
443utime(2). If called on a file descriptor, uses futimes(2) if available,
444otherwise returns ENOSYS, so this is not portable.
445
446Examples:
447
448 # set atime and mtime to current time (basically touch(1)):
449 aio_utime "path", undef, undef;
450 # set atime to current time and mtime to beginning of the epoch:
451 aio_utime "path", time, undef; # undef==0
452
453
454=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
455
456Works like perl's C<chown> function, except that C<undef> for either $uid
457or $gid is being interpreted as "do not change" (but -1 can also be used).
458
459Examples:
460
461 # same as "chown root path" in the shell:
462 aio_chown "path", 0, -1;
463 # same as above:
464 aio_chown "path", 0, undef;
465
466
467=item aio_truncate $fh_or_path, $offset, $callback->($status)
468
469Works like truncate(2) or ftruncate(2).
470
471
472=item aio_chmod $fh_or_path, $mode, $callback->($status)
473
474Works like perl's C<chmod> function.
475
476
394=item aio_unlink $pathname, $callback->($status) 477=item aio_unlink $pathname, $callback->($status)
395 478
396Asynchronously unlink (delete) a file and call the callback with the 479Asynchronously unlink (delete) a file and call the callback with the
397result code. 480result code.
398 481
482
483=item aio_mknod $path, $mode, $dev, $callback->($status)
484
485[EXPERIMENTAL]
486
487Asynchronously create a device node (or fifo). See mknod(2).
488
489The only (POSIX-) portable way of calling this function is:
490
491 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492
493
399=item aio_link $srcpath, $dstpath, $callback->($status) 494=item aio_link $srcpath, $dstpath, $callback->($status)
400 495
401Asynchronously create a new link to the existing object at C<$srcpath> at 496Asynchronously create a new link to the existing object at C<$srcpath> at
402the path C<$dstpath> and call the callback with the result code. 497the path C<$dstpath> and call the callback with the result code.
403 498
499
404=item aio_symlink $srcpath, $dstpath, $callback->($status) 500=item aio_symlink $srcpath, $dstpath, $callback->($status)
405 501
406Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 502Asynchronously 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. 503the path C<$dstpath> and call the callback with the result code.
408 504
505
506=item aio_readlink $path, $callback->($link)
507
508Asynchronously read the symlink specified by C<$path> and pass it to
509the callback. If an error occurs, nothing or undef gets passed to the
510callback.
511
512
409=item aio_rename $srcpath, $dstpath, $callback->($status) 513=item aio_rename $srcpath, $dstpath, $callback->($status)
410 514
411Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 515Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
412rename(2) and call the callback with the result code. 516rename(2) and call the callback with the result code.
413 517
518
519=item aio_mkdir $pathname, $mode, $callback->($status)
520
521Asynchronously mkdir (create) a directory and call the callback with
522the result code. C<$mode> will be modified by the umask at the time the
523request is executed, so do not change your umask.
524
525
414=item aio_rmdir $pathname, $callback->($status) 526=item aio_rmdir $pathname, $callback->($status)
415 527
416Asynchronously rmdir (delete) a directory and call the callback with the 528Asynchronously rmdir (delete) a directory and call the callback with the
417result code. 529result code.
530
418 531
419=item aio_readdir $pathname, $callback->($entries) 532=item aio_readdir $pathname, $callback->($entries)
420 533
421Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 534Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
422directory (i.e. opendir + readdir + closedir). The entries will not be 535directory (i.e. opendir + readdir + closedir). The entries will not be
423sorted, and will B<NOT> include the C<.> and C<..> entries. 536sorted, and will B<NOT> include the C<.> and C<..> entries.
424 537
425The callback a single argument which is either C<undef> or an array-ref 538The callback is passed a single argument which is either C<undef> or an
426with the filenames. 539array-ref with the filenames.
540
541
542=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
543
544Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
545behaviour and output format. In case of an error, C<$entries> will be
546C<undef>.
547
548The flags are a combination of the following constants, ORed together (the
549flags will also be passed to the callback, possibly modified):
550
551=over 4
552
553=item IO::AIO::READDIR_DENTS
554
555When this flag is off, then the callback gets an arrayref with of names
556only (as with C<aio_readdir>), otherwise it gets an arrayref with
557C<[$name, $type, $inode]> arrayrefs, each describing a single directory
558entry in more detail.
559
560C<$name> is the name of the entry.
561
562C<$type> is one of the C<IO::AIO::DT_xxx> constants:
563
564C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
565C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
566C<IO::AIO::DT_WHT>.
567
568C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
569know, you have to run stat yourself. Also, for speed reasons, the C<$type>
570scalars are read-only: you can not modify them.
571
572C<$inode> is the inode number (which might not be exact on systems with 64
573bit inode numbers and 32 bit perls). This field has unspecified content on
574systems that do not deliver the inode information.
575
576=item IO::AIO::READDIR_DIRS_FIRST
577
578When this flag is set, then the names will be returned in an order where
579likely directories come first. This is useful when you need to quickly
580find directories, or you want to find all directories while avoiding to
581stat() each entry.
582
583If the system returns type information in readdir, then this is used
584to find directories directly. Otherwise, likely directories are files
585beginning with ".", or otherwise files with no dots, of which files with
586short names are tried first.
587
588=item IO::AIO::READDIR_STAT_ORDER
589
590When this flag is set, then the names will be returned in an order
591suitable for stat()'ing each one. That is, when you plan to stat()
592all files in the given directory, then the returned order will likely
593be fastest.
594
595If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
596the likely dirs come first, resulting in a less optimal stat order.
597
598=item IO::AIO::READDIR_FOUND_UNKNOWN
599
600This flag should not be set when calling C<aio_readdirx>. Instead, it
601is being set by C<aio_readdirx>, when any of the C<$type>'s found were
602C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
603C<$type>'s are known, which can be used to speed up some algorithms.
604
605=back
606
607
608=item aio_load $path, $data, $callback->($status)
609
610This is a composite request that tries to fully load the given file into
611memory. Status is the same as with aio_read.
612
613=cut
614
615sub aio_load($$;$) {
616 my ($path, undef, $cb) = @_;
617 my $data = \$_[1];
618
619 my $pri = aioreq_pri;
620 my $grp = aio_group $cb;
621
622 aioreq_pri $pri;
623 add $grp aio_open $path, O_RDONLY, 0, sub {
624 my $fh = shift
625 or return $grp->result (-1);
626
627 aioreq_pri $pri;
628 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
629 $grp->result ($_[0]);
630 };
631 };
632
633 $grp
634}
635
636=item aio_copy $srcpath, $dstpath, $callback->($status)
637
638Try to copy the I<file> (directories not supported as either source or
639destination) from C<$srcpath> to C<$dstpath> and call the callback with
640the C<0> (error) or C<-1> ok.
641
642This is a composite request that creates the destination file with
643mode 0200 and copies the contents of the source file into it using
644C<aio_sendfile>, followed by restoring atime, mtime, access mode and
645uid/gid, in that order.
646
647If an error occurs, the partial destination file will be unlinked, if
648possible, except when setting atime, mtime, access mode and uid/gid, where
649errors are being ignored.
650
651=cut
652
653sub aio_copy($$;$) {
654 my ($src, $dst, $cb) = @_;
655
656 my $pri = aioreq_pri;
657 my $grp = aio_group $cb;
658
659 aioreq_pri $pri;
660 add $grp aio_open $src, O_RDONLY, 0, sub {
661 if (my $src_fh = $_[0]) {
662 my @stat = stat $src_fh; # hmm, might bock over nfs?
663
664 aioreq_pri $pri;
665 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
666 if (my $dst_fh = $_[0]) {
667 aioreq_pri $pri;
668 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
669 if ($_[0] == $stat[7]) {
670 $grp->result (0);
671 close $src_fh;
672
673 my $ch = sub {
674 aioreq_pri $pri;
675 add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
676 aioreq_pri $pri;
677 add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
678 aioreq_pri $pri;
679 add $grp aio_close $dst_fh;
680 }
681 };
682 };
683
684 aioreq_pri $pri;
685 add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
686 if ($_[0] < 0 && $! == ENOSYS) {
687 aioreq_pri $pri;
688 add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
689 } else {
690 $ch->();
691 }
692 };
693 } else {
694 $grp->result (-1);
695 close $src_fh;
696 close $dst_fh;
697
698 aioreq $pri;
699 add $grp aio_unlink $dst;
700 }
701 };
702 } else {
703 $grp->result (-1);
704 }
705 },
706
707 } else {
708 $grp->result (-1);
709 }
710 };
711
712 $grp
713}
714
715=item aio_move $srcpath, $dstpath, $callback->($status)
716
717Try to move the I<file> (directories not supported as either source or
718destination) from C<$srcpath> to C<$dstpath> and call the callback with
719the C<0> (error) or C<-1> ok.
720
721This is a composite request that tries to rename(2) the file first; if
722rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
723that is successful, unlinks the C<$srcpath>.
724
725=cut
726
727sub aio_move($$;$) {
728 my ($src, $dst, $cb) = @_;
729
730 my $pri = aioreq_pri;
731 my $grp = aio_group $cb;
732
733 aioreq_pri $pri;
734 add $grp aio_rename $src, $dst, sub {
735 if ($_[0] && $! == EXDEV) {
736 aioreq_pri $pri;
737 add $grp aio_copy $src, $dst, sub {
738 $grp->result ($_[0]);
739
740 if (!$_[0]) {
741 aioreq_pri $pri;
742 add $grp aio_unlink $src;
743 }
744 };
745 } else {
746 $grp->result ($_[0]);
747 }
748 };
749
750 $grp
751}
427 752
428=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 753=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429 754
430Scans a directory (similar to C<aio_readdir>) but additionally tries to 755Scans a directory (similar to C<aio_readdir>) but additionally tries to
431efficiently separate the entries of directory C<$path> into two sets of 756efficiently separate the entries of directory C<$path> into two sets of
… …
433recurse into (everything else, including symlinks to directories). 758recurse into (everything else, including symlinks to directories).
434 759
435C<aio_scandir> is a composite request that creates of many sub requests_ 760C<aio_scandir> is a composite request that creates of many sub requests_
436C<$maxreq> specifies the maximum number of outstanding aio requests that 761C<$maxreq> specifies the maximum number of outstanding aio requests that
437this function generates. If it is C<< <= 0 >>, then a suitable default 762this function generates. If it is C<< <= 0 >>, then a suitable default
438will be chosen (currently 6). 763will be chosen (currently 4).
439 764
440On error, the callback is called without arguments, otherwise it receives 765On error, the callback is called without arguments, otherwise it receives
441two array-refs with path-relative entry names. 766two array-refs with path-relative entry names.
442 767
443Example: 768Example:
… …
450 775
451Implementation notes. 776Implementation notes.
452 777
453The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. 778The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
454 779
780If readdir returns file type information, then this is used directly to
781find directories.
782
455After reading the directory, the modification time, size etc. of the 783Otherwise, after reading the directory, the modification time, size etc.
456directory before and after the readdir is checked, and if they match (and 784of 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 785match (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 786how many entries are directories (if >= 2). Otherwise, no knowledge of the
459of subdirectories will be assumed. 787number of subdirectories will be assumed.
460 788
461Then entries will be sorted into likely directories (everything without 789Then entries will be sorted into likely directories a non-initial dot
462a non-initial dot currently) and likely non-directories (everything 790currently) and likely non-directories (see C<aio_readdirx>). Then every
463else). Then every entry plus an appended C</.> will be C<stat>'ed, 791entry plus an appended C</.> will be C<stat>'ed, likely directories first,
464likely directories first. If that succeeds, it assumes that the entry 792in order of their inode numbers. If that succeeds, it assumes that the
465is a directory or a symlink to directory (which will be checked 793entry is a directory or a symlink to directory (which will be checked
466seperately). This is often faster than stat'ing the entry itself because 794seperately). This is often faster than stat'ing the entry itself because
467filesystems might detect the type of the entry without reading the inode 795filesystems might detect the type of the entry without reading the inode
468data (e.g. ext2fs filetype feature). 796data (e.g. ext2fs filetype feature), even on systems that cannot return
797the filetype information on readdir.
469 798
470If the known number of directories (link count - 2) has been reached, the 799If the known number of directories (link count - 2) has been reached, the
471rest of the entries is assumed to be non-directories. 800rest of the entries is assumed to be non-directories.
472 801
473This only works with certainty on POSIX (= UNIX) filesystems, which 802This only works with certainty on POSIX (= UNIX) filesystems, which
… …
477as those tend to return 0 or 1 as link counts, which disables the 806as those tend to return 0 or 1 as link counts, which disables the
478directory counting heuristic. 807directory counting heuristic.
479 808
480=cut 809=cut
481 810
482sub aio_scandir($$$) { 811sub aio_scandir($$;$) {
483 my ($path, $maxreq, $cb) = @_; 812 my ($path, $maxreq, $cb) = @_;
484 813
814 my $pri = aioreq_pri;
815
485 my $grp = aio_group $cb; 816 my $grp = aio_group $cb;
486 817
487 $maxreq = 6 if $maxreq <= 0; 818 $maxreq = 4 if $maxreq <= 0;
488 819
489 # stat once 820 # stat once
821 aioreq_pri $pri;
490 add $grp aio_stat $path, sub { 822 add $grp aio_stat $path, sub {
491 return $grp->result () if $_[0]; 823 return $grp->result () if $_[0];
492 my $now = time; 824 my $now = time;
493 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 825 my $hash1 = join ":", (stat _)[0,1,3,7,9];
494 826
495 # read the directory entries 827 # read the directory entries
828 aioreq_pri $pri;
496 add $grp aio_readdir $path, sub { 829 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
497 my $entries = shift 830 my $entries = shift
498 or return $grp->result (); 831 or return $grp->result ();
499 832
500 # stat the dir another time 833 # stat the dir another time
834 aioreq_pri $pri;
501 add $grp aio_stat $path, sub { 835 add $grp aio_stat $path, sub {
502 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 836 my $hash2 = join ":", (stat _)[0,1,3,7,9];
503 837
504 my $ndirs; 838 my $ndirs;
505 839
506 # take the slow route if anything looks fishy 840 # take the slow route if anything looks fishy
507 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 841 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508 $ndirs = -1; 842 $ndirs = -1;
509 } else { 843 } else {
510 # if nlink == 2, we are finished 844 # if nlink == 2, we are finished
511 # on non-posix-fs's, we rely on nlink < 2 845 # for non-posix-fs's, we rely on nlink < 2
512 $ndirs = (stat _)[3] - 2 846 $ndirs = (stat _)[3] - 2
513 or return $grp->result ([], $entries); 847 or return $grp->result ([], $entries);
514 } 848 }
515 849
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); 850 my (@dirs, @nondirs);
524 851
525 my $statgrp = add $grp aio_group sub { 852 my $statgrp = add $grp aio_group sub {
526 $grp->result (\@dirs, \@nondirs); 853 $grp->result (\@dirs, \@nondirs);
527 }; 854 };
528 855
529 limit $statgrp $maxreq; 856 limit $statgrp $maxreq;
530 feed $statgrp sub { 857 feed $statgrp sub {
531 return unless @$entries; 858 return unless @$entries;
532 my $entry = pop @$entries; 859 my $entry = shift @$entries;
533 860
861 aioreq_pri $pri;
534 add $statgrp aio_stat "$path/$entry/.", sub { 862 add $statgrp aio_stat "$path/$entry/.", sub {
535 if ($_[0] < 0) { 863 if ($_[0] < 0) {
536 push @nondirs, $entry; 864 push @nondirs, $entry;
537 } else { 865 } else {
538 # need to check for real directory 866 # need to check for real directory
867 aioreq_pri $pri;
539 add $statgrp aio_lstat "$path/$entry", sub { 868 add $statgrp aio_lstat "$path/$entry", sub {
540 if (-d _) { 869 if (-d _) {
541 push @dirs, $entry; 870 push @dirs, $entry;
542 871
543 unless (--$ndirs) { 872 unless (--$ndirs) {
… …
556 }; 885 };
557 886
558 $grp 887 $grp
559} 888}
560 889
890=item aio_rmtree $path, $callback->($status)
891
892Delete a directory tree starting (and including) C<$path>, return the
893status of the final C<rmdir> only. This is a composite request that
894uses C<aio_scandir> to recurse into and rmdir directories, and unlink
895everything else.
896
897=cut
898
899sub aio_rmtree;
900sub aio_rmtree($;$) {
901 my ($path, $cb) = @_;
902
903 my $pri = aioreq_pri;
904 my $grp = aio_group $cb;
905
906 aioreq_pri $pri;
907 add $grp aio_scandir $path, 0, sub {
908 my ($dirs, $nondirs) = @_;
909
910 my $dirgrp = aio_group sub {
911 add $grp aio_rmdir $path, sub {
912 $grp->result ($_[0]);
913 };
914 };
915
916 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
917 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
918
919 add $grp $dirgrp;
920 };
921
922 $grp
923}
924
925=item aio_sync $callback->($status)
926
927Asynchronously call sync and call the callback when finished.
928
561=item aio_fsync $fh, $callback->($status) 929=item aio_fsync $fh, $callback->($status)
562 930
563Asynchronously call fsync on the given filehandle and call the callback 931Asynchronously call fsync on the given filehandle and call the callback
564with the fsync result code. 932with the fsync result code.
565 933
… …
568Asynchronously call fdatasync on the given filehandle and call the 936Asynchronously call fdatasync on the given filehandle and call the
569callback with the fdatasync result code. 937callback with the fdatasync result code.
570 938
571If this call isn't available because your OS lacks it or it couldn't be 939If 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. 940detected, it will be emulated by calling C<fsync> instead.
941
942=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
943
944Sync the data portion of the file specified by C<$offset> and C<$length>
945to disk (but NOT the metadata), by calling the Linux-specific
946sync_file_range call. If sync_file_range is not available or it returns
947ENOSYS, then fdatasync or fsync is being substituted.
948
949C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
950C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
951C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
952manpage for details.
953
954=item aio_pathsync $path, $callback->($status)
955
956This request tries to open, fsync and close the given path. This is a
957composite request intended to sync directories after directory operations
958(E.g. rename). This might not work on all operating systems or have any
959specific effect, but usually it makes sure that directory changes get
960written to disc. It works for anything that can be opened for read-only,
961not just directories.
962
963Passes C<0> when everything went ok, and C<-1> on error.
964
965=cut
966
967sub aio_pathsync($;$) {
968 my ($path, $cb) = @_;
969
970 my $pri = aioreq_pri;
971 my $grp = aio_group $cb;
972
973 aioreq_pri $pri;
974 add $grp aio_open $path, O_RDONLY, 0, sub {
975 my ($fh) = @_;
976 if ($fh) {
977 aioreq_pri $pri;
978 add $grp aio_fsync $fh, sub {
979 $grp->result ($_[0]);
980
981 aioreq_pri $pri;
982 add $grp aio_close $fh;
983 };
984 } else {
985 $grp->result (-1);
986 }
987 };
988
989 $grp
990}
573 991
574=item aio_group $callback->(...) 992=item aio_group $callback->(...)
575 993
576This is a very special aio request: Instead of doing something, it is a 994This 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 995container for other aio requests, which is useful if you want to bundle
… …
627=item cancel $req 1045=item cancel $req
628 1046
629Cancels the request, if possible. Has the effect of skipping execution 1047Cancels the request, if possible. Has the effect of skipping execution
630when entering the B<execute> state and skipping calling the callback when 1048when entering the B<execute> state and skipping calling the callback when
631entering the the B<result> state, but will leave the request otherwise 1049entering the the B<result> state, but will leave the request otherwise
632untouched. That means that requests that currently execute will not be 1050untouched (with the exception of readdir). That means that requests that
633stopped and resources held by the request will not be freed prematurely. 1051currently execute will not be stopped and resources held by the request
1052will not be freed prematurely.
634 1053
635=item cb $req $callback->(...) 1054=item cb $req $callback->(...)
636 1055
637Replace (or simply set) the callback registered to the request. 1056Replace (or simply set) the callback registered to the request.
638 1057
… …
689Their lifetime, simplified, looks like this: when they are empty, they 1108Their lifetime, simplified, looks like this: when they are empty, they
690will finish very quickly. If they contain only requests that are in the 1109will finish very quickly. If they contain only requests that are in the
691C<done> state, they will also finish. Otherwise they will continue to 1110C<done> state, they will also finish. Otherwise they will continue to
692exist. 1111exist.
693 1112
694That means after creating a group you have some time to add requests. And 1113That 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 1114(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 1115the C<poll_cb>). And in the callbacks of those requests, you can add
697itself finish. 1116further requests to the group. And only when all those requests have
1117finished will the the group itself finish.
698 1118
699=over 4 1119=over 4
700 1120
701=item add $grp ... 1121=item add $grp ...
702 1122
… …
714itself. Useful when you queued a lot of events but got a result early. 1134itself. Useful when you queued a lot of events but got a result early.
715 1135
716=item $grp->result (...) 1136=item $grp->result (...)
717 1137
718Set the result value(s) that will be passed to the group callback when all 1138Set the result value(s) that will be passed to the group callback when all
719subrequests have finished. By default, no argument will be passed. 1139subrequests have finished and set the groups errno to the current value
1140of errno (just like calling C<errno> without an error number). By default,
1141no argument will be passed and errno is zero.
1142
1143=item $grp->errno ([$errno])
1144
1145Sets the group errno value to C<$errno>, or the current value of errno
1146when the argument is missing.
1147
1148Every aio request has an associated errno value that is restored when
1149the callback is invoked. This method lets you change this value from its
1150default (0).
1151
1152Calling C<result> will also set errno, so make sure you either set C<$!>
1153before the call to C<result>, or call c<errno> after it.
720 1154
721=item feed $grp $callback->($grp) 1155=item feed $grp $callback->($grp)
722 1156
723Sets a feeder/generator on this group: every group can have an attached 1157Sets a feeder/generator on this group: every group can have an attached
724generator that generates requests if idle. The idea behind this is that, 1158generator 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, 1159although you could just queue as many requests as you want in a group,
726this might starve other requests for a potentially long time. For 1160this might starve other requests for a potentially long time. For example,
727example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> 1161C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
728requests, delaying any later requests for a long time. 1162delaying any later requests for a long time.
729 1163
730To avoid this, and allow incremental generation of requests, you can 1164To avoid this, and allow incremental generation of requests, you can
731instead a group and set a feeder on it that generates those requests. The 1165instead 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>, 1166feed 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 1167below) requests active in the group itself and is expected to queue more
… …
737not impose any limits). 1171not impose any limits).
738 1172
739If the feed does not queue more requests when called, it will be 1173If the feed does not queue more requests when called, it will be
740automatically removed from the group. 1174automatically removed from the group.
741 1175
742If the feed limit is C<0>, it will be set to C<2> automatically. 1176If the feed limit is C<0> when this method is called, it will be set to
1177C<2> automatically.
743 1178
744Example: 1179Example:
745 1180
746 # stat all files in @files, but only ever use four aio requests concurrently: 1181 # stat all files in @files, but only ever use four aio requests concurrently:
747 1182
… …
759Sets the feeder limit for the group: The feeder will be called whenever 1194Sets the feeder limit for the group: The feeder will be called whenever
760the group contains less than this many requests. 1195the group contains less than this many requests.
761 1196
762Setting the limit to C<0> will pause the feeding process. 1197Setting the limit to C<0> will pause the feeding process.
763 1198
1199The default value for the limit is C<0>, but note that setting a feeder
1200automatically bumps it up to C<2>.
1201
764=back 1202=back
765 1203
766=head2 SUPPORT FUNCTIONS 1204=head2 SUPPORT FUNCTIONS
767 1205
1206=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1207
768=over 4 1208=over 4
769 1209
770=item $fileno = IO::AIO::poll_fileno 1210=item $fileno = IO::AIO::poll_fileno
771 1211
772Return the I<request result pipe file descriptor>. This filehandle must be 1212Return the I<request result pipe file descriptor>. This filehandle must be
773polled for reading by some mechanism outside this module (e.g. Event or 1213polled 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 1214select and so on, see below or the SYNOPSIS). If the pipe becomes readable
775to call C<poll_cb> to check the results. 1215you have to call C<poll_cb> to check the results.
776 1216
777See C<poll_cb> for an example. 1217See C<poll_cb> for an example.
778 1218
779=item IO::AIO::poll_cb 1219=item IO::AIO::poll_cb
780 1220
781Process all outstanding events on the result pipe. You have to call this 1221Process some outstanding events on the result pipe. You have to call this
782regularly. Returns the number of events processed. Returns immediately 1222regularly. Returns C<0> if all events could be processed, or C<-1> if it
783when no events are outstanding. 1223returned earlier for whatever reason. Returns immediately when no events
1224are outstanding. The amount of events processed depends on the settings of
1225C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1226
1227If not all requests were processed for whatever reason, the filehandle
1228will still be ready when C<poll_cb> returns, so normally you don't have to
1229do anything special to have it called later.
784 1230
785Example: Install an Event watcher that automatically calls 1231Example: Install an Event watcher that automatically calls
786IO::AIO::poll_cb with high priority: 1232IO::AIO::poll_cb with high priority (more examples can be found in the
1233SYNOPSIS section, at the top of this document):
787 1234
788 Event->io (fd => IO::AIO::poll_fileno, 1235 Event->io (fd => IO::AIO::poll_fileno,
789 poll => 'r', async => 1, 1236 poll => 'r', async => 1,
790 cb => \&IO::AIO::poll_cb); 1237 cb => \&IO::AIO::poll_cb);
791 1238
1239=item IO::AIO::max_poll_reqs $nreqs
1240
1241=item IO::AIO::max_poll_time $seconds
1242
1243These set the maximum number of requests (default C<0>, meaning infinity)
1244that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1245the maximum amount of time (default C<0>, meaning infinity) spent in
1246C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1247of time C<poll_cb> is allowed to use).
1248
1249Setting C<max_poll_time> to a non-zero value creates an overhead of one
1250syscall per request processed, which is not normally a problem unless your
1251callbacks are really really fast or your OS is really really slow (I am
1252not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1253
1254Setting these is useful if you want to ensure some level of
1255interactiveness when perl is not fast enough to process all requests in
1256time.
1257
1258For interactive programs, values such as C<0.01> to C<0.1> should be fine.
1259
1260Example: Install an Event watcher that automatically calls
1261IO::AIO::poll_cb with low priority, to ensure that other parts of the
1262program get the CPU sometimes even under high AIO load.
1263
1264 # try not to spend much more than 0.1s in poll_cb
1265 IO::AIO::max_poll_time 0.1;
1266
1267 # use a low priority so other tasks have priority
1268 Event->io (fd => IO::AIO::poll_fileno,
1269 poll => 'r', nice => 1,
1270 cb => &IO::AIO::poll_cb);
1271
792=item IO::AIO::poll_wait 1272=item IO::AIO::poll_wait
793 1273
1274If there are any outstanding requests and none of them in the result
794Wait till the result filehandle becomes ready for reading (simply does a 1275phase, wait till the result filehandle becomes ready for reading (simply
795C<select> on the filehandle. This is useful if you want to synchronously wait 1276does a C<select> on the filehandle. This is useful if you want to
796for some requests to finish). 1277synchronously wait for some requests to finish).
797 1278
798See C<nreqs> for an example. 1279See C<nreqs> for an example.
799 1280
1281=item IO::AIO::poll
1282
1283Waits until some requests have been handled.
1284
1285Returns the number of requests processed, but is otherwise strictly
1286equivalent to:
1287
1288 IO::AIO::poll_wait, IO::AIO::poll_cb
1289
800=item IO::AIO::nreqs 1290=item IO::AIO::flush
801 1291
802Returns the number of requests currently outstanding (i.e. for which their 1292Wait till all outstanding AIO requests have been handled.
803callback has not been invoked yet).
804 1293
805Example: wait till there are no outstanding requests anymore: 1294Strictly equivalent to:
806 1295
807 IO::AIO::poll_wait, IO::AIO::poll_cb 1296 IO::AIO::poll_wait, IO::AIO::poll_cb
808 while IO::AIO::nreqs; 1297 while IO::AIO::nreqs;
809 1298
810=item IO::AIO::flush 1299=back
811 1300
812Wait till all outstanding AIO requests have been handled. 1301=head3 CONTROLLING THE NUMBER OF THREADS
813 1302
814Strictly equivalent to: 1303=over
815
816 IO::AIO::poll_wait, IO::AIO::poll_cb
817 while IO::AIO::nreqs;
818
819=item IO::AIO::poll
820
821Waits until some requests have been handled.
822
823Strictly equivalent to:
824
825 IO::AIO::poll_wait, IO::AIO::poll_cb
826 if IO::AIO::nreqs;
827 1304
828=item IO::AIO::min_parallel $nthreads 1305=item IO::AIO::min_parallel $nthreads
829 1306
830Set the minimum number of AIO threads to C<$nthreads>. The current 1307Set the minimum number of AIO threads to C<$nthreads>. The current
831default is C<8>, which means eight asynchronous operations can execute 1308default is C<8>, which means eight asynchronous operations can execute
832concurrently at any one time (the number of outstanding requests, 1309concurrently at any one time (the number of outstanding requests,
833however, is unlimited). 1310however, is unlimited).
834 1311
835IO::AIO starts threads only on demand, when an AIO request is queued and 1312IO::AIO starts threads only on demand, when an AIO request is queued and
836no free thread exists. 1313no free thread exists. Please note that queueing up a hundred requests can
1314create demand for a hundred threads, even if it turns out that everything
1315is in the cache and could have been processed faster by a single thread.
837 1316
838It is recommended to keep the number of threads relatively low, as some 1317It is recommended to keep the number of threads relatively low, as some
839Linux kernel versions will scale negatively with the number of threads 1318Linux kernel versions will scale negatively with the number of threads
840(higher parallelity => MUCH higher latency). With current Linux 2.6 1319(higher parallelity => MUCH higher latency). With current Linux 2.6
841versions, 4-32 threads should be fine. 1320versions, 4-32 threads should be fine.
… …
855This module automatically runs C<max_parallel 0> at program end, to ensure 1334This module automatically runs C<max_parallel 0> at program end, to ensure
856that all threads are killed and that there are no outstanding requests. 1335that all threads are killed and that there are no outstanding requests.
857 1336
858Under normal circumstances you don't need to call this function. 1337Under normal circumstances you don't need to call this function.
859 1338
1339=item IO::AIO::max_idle $nthreads
1340
1341Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1342threads that did not get a request to process within 10 seconds). That
1343means if a thread becomes idle while C<$nthreads> other threads are also
1344idle, it will free its resources and exit.
1345
1346This is useful when you allow a large number of threads (e.g. 100 or 1000)
1347to allow for extremely high load situations, but want to free resources
1348under normal circumstances (1000 threads can easily consume 30MB of RAM).
1349
1350The default is probably ok in most situations, especially if thread
1351creation is fast. If thread creation is very slow on your system you might
1352want to use larger values.
1353
860=item $oldnreqs = IO::AIO::max_outstanding $nreqs 1354=item IO::AIO::max_outstanding $maxreqs
861 1355
862[REMOVED] 1356This is a very bad function to use in interactive programs because it
1357blocks, and a bad way to reduce concurrency because it is inexact: Better
1358use an C<aio_group> together with a feed callback.
863 1359
864Pre-2.x versions used max_outstanding for a crude request queue length limit.
865
866In 2.x+ you are advised to use a group and a feeder to limit
867concurrency. The max_outstanding feature ran very unstable (endless
868recursions causing segfaults, bad interaction with groups etc.) and was
869removed.
870
871I am deeply sorry, but I am still on the hunt for a good limiting interface.
872
873Original description was as follows:
874
875Sets the maximum number of outstanding requests to C<$nreqs>. If you try 1360Sets the maximum number of outstanding requests to C<$nreqs>. If you
876to queue up more than this number of requests, the caller will block until 1361do queue up more than this number of requests, the next call to the
877some requests have been handled. 1362C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1363function will block until the limit is no longer exceeded.
1364
1365The default value is very large, so there is no practical limit on the
1366number of outstanding requests.
1367
1368You can still queue as many requests as you want. Therefore,
1369C<max_outstanding> is mainly useful in simple scripts (with low values) or
1370as a stop gap to shield against fatal memory overflow (with large values).
878 1371
879=back 1372=back
880 1373
1374=head3 STATISTICAL INFORMATION
1375
1376=over
1377
1378=item IO::AIO::nreqs
1379
1380Returns the number of requests currently in the ready, execute or pending
1381states (i.e. for which their callback has not been invoked yet).
1382
1383Example: wait till there are no outstanding requests anymore:
1384
1385 IO::AIO::poll_wait, IO::AIO::poll_cb
1386 while IO::AIO::nreqs;
1387
1388=item IO::AIO::nready
1389
1390Returns the number of requests currently in the ready state (not yet
1391executed).
1392
1393=item IO::AIO::npending
1394
1395Returns the number of requests currently in the pending state (executed,
1396but not yet processed by poll_cb).
1397
1398=back
1399
1400=head3 MISCELLANEOUS FUNCTIONS
1401
1402IO::AIO implements some functions that might be useful, but are not
1403asynchronous.
1404
1405=over 4
1406
1407=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1408
1409Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1410but is blocking (this makes most sense if you know the input data is
1411likely cached already and the output filehandle is set to non-blocking
1412operations).
1413
1414Returns the number of bytes copied, or C<-1> on error.
1415
1416=item IO::AIO::fadvise $fh, $offset, $len, $advice
1417
1418Simply calls the C<posix_fadvise> function (see it's
1419manpage for details). The following advice constants are
1420avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1421C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1422C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1423
1424On systems that do not implement C<posix_fadvise>, this function returns
1425ENOSYS, otherwise the return value of C<posix_fadvise>.
1426
1427=back
1428
881=cut 1429=cut
882 1430
883# support function to convert a fd into a perl filehandle
884sub _fd2fh {
885 return undef if $_[0] < 0;
886
887 # try to generate nice filehandles
888 my $sym = "IO::AIO::fd#$_[0]";
889 local *$sym;
890
891 open *$sym, "+<&=$_[0]" # usually works under any unix
892 or open *$sym, "<&=$_[0]" # cygwin needs this
893 or open *$sym, ">&=$_[0]" # or this
894 or return undef;
895
896 *$sym
897}
898
899min_parallel 8; 1431min_parallel 8;
900 1432
901END { 1433END { flush }
902 max_parallel 0;
903}
904 1434
9051; 14351;
906 1436
907=head2 FORK BEHAVIOUR 1437=head2 FORK BEHAVIOUR
908 1438
… …
928bytes of memory. In addition, stat requests need a stat buffer (possibly 1458bytes of memory. In addition, stat requests need a stat buffer (possibly
929a few hundred bytes), readdir requires a result buffer and so on. Perl 1459a few hundred bytes), readdir requires a result buffer and so on. Perl
930scalars and other data passed into aio requests will also be locked and 1460scalars and other data passed into aio requests will also be locked and
931will consume memory till the request has entered the done state. 1461will consume memory till the request has entered the done state.
932 1462
933This is now awfully much, so queuing lots of requests is not usually a 1463This is not awfully much, so queuing lots of requests is not usually a
934problem. 1464problem.
935 1465
936Per-thread usage: 1466Per-thread usage:
937 1467
938In the execution phase, some aio requests require more memory for 1468In the execution phase, some aio requests require more memory for
… …
943 1473
944Known bugs will be fixed in the next release. 1474Known bugs will be fixed in the next release.
945 1475
946=head1 SEE ALSO 1476=head1 SEE ALSO
947 1477
948L<Coro::AIO>. 1478L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1479more natural syntax.
949 1480
950=head1 AUTHOR 1481=head1 AUTHOR
951 1482
952 Marc Lehmann <schmorp@schmorp.de> 1483 Marc Lehmann <schmorp@schmorp.de>
953 http://home.schmorp.de/ 1484 http://home.schmorp.de/

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