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Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs.
Revision 1.153 by root, Sat Jun 13 13:33:00 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 $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);
… …
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.
58
59Asynchronous means that operations that can normally block your program
60(e.g. reading from disk) will be done asynchronously: the operation
61will still block, but you can do something else in the meantime. This
62is extremely useful for programs that need to stay interactive even
63when doing heavy I/O (GUI programs, high performance network servers
64etc.), but can also be used to easily do operations in parallel that are
65normally done sequentially, e.g. stat'ing many files, which is much faster
66on a RAID volume or over NFS when you do a number of stat operations
67concurrently.
68
69While most of this works on all types of file descriptors (for
70example sockets), using these functions on file descriptors that
71support nonblocking operation (again, sockets, pipes etc.) is very
72inefficient. Use an event loop for that (such as the L<Event|Event>
73module): IO::AIO will naturally fit into such an event loop itself.
55 74
56In this version, a number of threads are started that execute your 75In this version, a number of threads are started that execute your
57requests and signal their completion. You don't need thread support 76requests and signal their completion. You don't need thread support
58in perl, and the threads created by this module will not be visible 77in 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 78to perl. In the future, this module might make use of the native aio
60functions available on many operating systems. However, they are often 79functions available on many operating systems. However, they are often
61not well-supported or restricted (Linux doesn't allow them on normal 80not well-supported or restricted (GNU/Linux doesn't allow them on normal
62files currently, for example), and they would only support aio_read and 81files currently, for example), and they would only support aio_read and
63aio_write, so the remaining functionality would have to be implemented 82aio_write, so the remaining functionality would have to be implemented
64using threads anyway. 83using threads anyway.
65 84
66Although the module will work with in the presence of other (Perl-) 85Although the module will work in the presence of other (Perl-) threads,
67threads, it is currently not reentrant in any way, so use appropriate 86it is currently not reentrant in any way, so use appropriate locking
68locking yourself, always call C<poll_cb> from within the same thread, or 87yourself, always call C<poll_cb> from within the same thread, or never
69never call C<poll_cb> (or other C<aio_> functions) recursively. 88call C<poll_cb> (or other C<aio_> functions) recursively.
89
90=head2 EXAMPLE
91
92This is a simple example that uses the Event module and loads
93F</etc/passwd> asynchronously:
94
95 use Fcntl;
96 use Event;
97 use IO::AIO;
98
99 # register the IO::AIO callback with Event
100 Event->io (fd => IO::AIO::poll_fileno,
101 poll => 'r',
102 cb => \&IO::AIO::poll_cb);
103
104 # queue the request to open /etc/passwd
105 aio_open "/etc/passwd", O_RDONLY, 0, sub {
106 my $fh = shift
107 or die "error while opening: $!";
108
109 # stat'ing filehandles is generally non-blocking
110 my $size = -s $fh;
111
112 # queue a request to read the file
113 my $contents;
114 aio_read $fh, 0, $size, $contents, 0, sub {
115 $_[0] == $size
116 or die "short read: $!";
117
118 close $fh;
119
120 # file contents now in $contents
121 print $contents;
122
123 # exit event loop and program
124 Event::unloop;
125 };
126 };
127
128 # possibly queue up other requests, or open GUI windows,
129 # check for sockets etc. etc.
130
131 # process events as long as there are some:
132 Event::loop;
70 133
71=head1 REQUEST ANATOMY AND LIFETIME 134=head1 REQUEST ANATOMY AND LIFETIME
72 135
73Every C<aio_*> function creates a request. which is a C data structure not 136Every C<aio_*> function creates a request. which is a C data structure not
74directly visible to Perl. 137directly visible to Perl.
… …
116Request has reached the end of its lifetime and holds no resources anymore 179Request 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 180(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 181aio request is severed and calling its methods will either do nothing or
119result in a runtime error). 182result in a runtime error).
120 183
184=back
185
121=cut 186=cut
122 187
123package IO::AIO; 188package IO::AIO;
189
190use Carp ();
124 191
125no warnings; 192no warnings;
126use strict 'vars'; 193use strict 'vars';
127 194
128use base 'Exporter'; 195use base 'Exporter';
129 196
130BEGIN { 197BEGIN {
131 our $VERSION = '2.0'; 198 our $VERSION = '3.22';
132 199
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 200 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 201 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 202 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
136 aio_group aio_nop); 203 aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
204 aio_rename aio_link aio_move aio_copy aio_group
205 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206 aio_chmod aio_utime aio_truncate);
207
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 208 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 209 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel nreqs nready npending); 210 min_parallel max_parallel max_idle
211 nreqs nready npending nthreads
212 max_poll_time max_poll_reqs);
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 $prev_pri = aioreq_pri [$pri] 259=item $prev_pri = aioreq_pri [$pri]
181 260
… …
201 aio_read $_[0], ..., sub { 280 aio_read $_[0], ..., sub {
202 ... 281 ...
203 }; 282 };
204 }; 283 };
205 284
285
206=item aioreq_nice $pri_adjust 286=item aioreq_nice $pri_adjust
207 287
208Similar 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
209priority, so effects are cumulative. 289priority, so the effect is cumulative.
290
210 291
211=item aio_open $pathname, $flags, $mode, $callback->($fh) 292=item aio_open $pathname, $flags, $mode, $callback->($fh)
212 293
213Asynchronously 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
214created filehandle for the file. 295created filehandle for the file.
… …
220list. They are the same as used by C<sysopen>. 301list. They are the same as used by C<sysopen>.
221 302
222Likewise, 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
223didn'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>,
224except 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,
225and C<0666> or C<0777> if you do). 306and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
307by the umask in effect then the request is being executed, so better never
308change the umask.
226 309
227Example: 310Example:
228 311
229 aio_open "/etc/passwd", O_RDONLY, 0, sub { 312 aio_open "/etc/passwd", O_RDONLY, 0, sub {
230 if ($_[0]) { 313 if ($_[0]) {
… …
233 } else { 316 } else {
234 die "open failed: $!\n"; 317 die "open failed: $!\n";
235 } 318 }
236 }; 319 };
237 320
321
238=item aio_close $fh, $callback->($status) 322=item aio_close $fh, $callback->($status)
239 323
240Asynchronously close a file and call the callback with the result 324Asynchronously close a file and call the callback with the result
241code. I<WARNING:> although accepted, you should not pass in a perl 325code.
242filehandle here, as perl will likely close the file descriptor another
243time when the filehandle is destroyed. Normally, you can safely call perls
244C<close> or just let filehandles go out of scope.
245 326
246This 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
247therefore 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
248 338
249=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 339=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250 340
251=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 341=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252 342
253Reads 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
254into 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<$dataoffset>
255callback without the actual number of bytes read (or -1 on error, just 345and calls the callback without the actual number of bytes read (or -1 on
256like the syscall). 346error, just like the syscall).
347
348C<aio_read> will, like C<sysread>, shrink or grow the C<$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<$data>.
257 360
258The C<$data> scalar I<MUST NOT> be modified in any way while the request 361The C<$data> scalar I<MUST NOT> be modified in any way while the request
259is outstanding. Modifying it can result in segfaults or WW3 (if the 362is outstanding. Modifying it can result in segfaults or World War III (if
260necessary/optional hardware is installed). 363the necessary/optional hardware is installed).
261 364
262Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 365Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263offset C<0> within the scalar: 366offset C<0> within the scalar:
264 367
265 aio_read $fh, 7, 15, $buffer, 0, sub { 368 aio_read $fh, 7, 15, $buffer, 0, sub {
266 $_[0] > 0 or die "read error: $!"; 369 $_[0] > 0 or die "read error: $!";
267 print "read $_[0] bytes: <$buffer>\n"; 370 print "read $_[0] bytes: <$buffer>\n";
268 }; 371 };
269 372
270=item aio_move $srcpath, $dstpath, $callback->($status)
271
272Try to move the I<file> (directories not supported as either source or
273destination) from C<$srcpath> to C<$dstpath> and call the callback with
274the C<0> (error) or C<-1> ok.
275
276This is a composite request that tries to rename(2) the file first. If
277rename files with C<EXDEV>, it creates the destination file with mode 0200
278and copies the contents of the source file into it using C<aio_sendfile>,
279followed by restoring atime, mtime, access mode and uid/gid, in that
280order, and unlinking the C<$srcpath>.
281
282If an error occurs, the partial destination file will be unlinked, if
283possible, except when setting atime, mtime, access mode and uid/gid, where
284errors are being ignored.
285
286=cut
287
288sub aio_move($$$) {
289 my ($src, $dst, $cb) = @_;
290
291 my $pri = aioreq_pri;
292 my $grp = aio_group $cb;
293
294 aioreq_pri $pri;
295 add $grp aio_rename $src, $dst, sub {
296 if ($_[0] && $! == EXDEV) {
297 aioreq_pri $pri;
298 add $grp aio_open $src, O_RDONLY, 0, sub {
299 if (my $src_fh = $_[0]) {
300 my @stat = stat $src_fh;
301
302 aioreq_pri $pri;
303 add $grp aio_open $dst, O_WRONLY, 0200, sub {
304 if (my $dst_fh = $_[0]) {
305 aioreq_pri $pri;
306 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
307 close $src_fh;
308
309 if ($_[0] == $stat[7]) {
310 utime $stat[8], $stat[9], $dst;
311 chmod $stat[2] & 07777, $dst_fh;
312 chown $stat[4], $stat[5], $dst_fh;
313 close $dst_fh;
314
315 aioreq_pri $pri;
316 add $grp aio_unlink $src, sub {
317 $grp->result ($_[0]);
318 };
319 } else {
320 my $errno = $!;
321 aioreq_pri $pri;
322 add $grp aio_unlink $dst, sub {
323 $! = $errno;
324 $grp->result (-1);
325 };
326 }
327 };
328 } else {
329 $grp->result (-1);
330 }
331 },
332
333 } else {
334 $grp->result (-1);
335 }
336 };
337 } else {
338 $grp->result ($_[0]);
339 }
340 };
341
342 $grp
343}
344 373
345=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)
346 375
347Tries 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
348reading 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
… …
362C<$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
363bytes 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
364provides 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
365value 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
366read. 395read.
396
367 397
368=item aio_readahead $fh,$offset,$length, $callback->($retval) 398=item aio_readahead $fh,$offset,$length, $callback->($retval)
369 399
370C<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
371subsequent 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>
… …
377file. The current file offset of the file is left unchanged. 407file. The current file offset of the file is left unchanged.
378 408
379If 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
380emulated by simply reading the data, which would have a similar effect. 410emulated by simply reading the data, which would have a similar effect.
381 411
412
382=item aio_stat $fh_or_path, $callback->($status) 413=item aio_stat $fh_or_path, $callback->($status)
383 414
384=item aio_lstat $fh, $callback->($status) 415=item aio_lstat $fh, $callback->($status)
385 416
386Works 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
… …
399 aio_stat "/etc/passwd", sub { 430 aio_stat "/etc/passwd", sub {
400 $_[0] and die "stat failed: $!"; 431 $_[0] and die "stat failed: $!";
401 print "size is ", -s _, "\n"; 432 print "size is ", -s _, "\n";
402 }; 433 };
403 434
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
404=item aio_unlink $pathname, $callback->($status) 477=item aio_unlink $pathname, $callback->($status)
405 478
406Asynchronously unlink (delete) a file and call the callback with the 479Asynchronously unlink (delete) a file and call the callback with the
407result code. 480result code.
408 481
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
409=item aio_link $srcpath, $dstpath, $callback->($status) 494=item aio_link $srcpath, $dstpath, $callback->($status)
410 495
411Asynchronously 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
412the path C<$dstpath> and call the callback with the result code. 497the path C<$dstpath> and call the callback with the result code.
413 498
499
414=item aio_symlink $srcpath, $dstpath, $callback->($status) 500=item aio_symlink $srcpath, $dstpath, $callback->($status)
415 501
416Asynchronously 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
417the path C<$dstpath> and call the callback with the result code. 503the path C<$dstpath> and call the callback with the result code.
418 504
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
419=item aio_rename $srcpath, $dstpath, $callback->($status) 513=item aio_rename $srcpath, $dstpath, $callback->($status)
420 514
421Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 515Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422rename(2) and call the callback with the result code. 516rename(2) and call the callback with the result code.
423 517
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
424=item aio_rmdir $pathname, $callback->($status) 526=item aio_rmdir $pathname, $callback->($status)
425 527
426Asynchronously rmdir (delete) a directory and call the callback with the 528Asynchronously rmdir (delete) a directory and call the callback with the
427result code. 529result code.
530
428 531
429=item aio_readdir $pathname, $callback->($entries) 532=item aio_readdir $pathname, $callback->($entries)
430 533
431Unlike 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
432directory (i.e. opendir + readdir + closedir). The entries will not be 535directory (i.e. opendir + readdir + closedir). The entries will not be
433sorted, and will B<NOT> include the C<.> and C<..> entries. 536sorted, and will B<NOT> include the C<.> and C<..> entries.
434 537
435The 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
436with 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). On systems that do not deliver the
574inode information, this will always be zero.
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}
437 752
438=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 753=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439 754
440Scans a directory (similar to C<aio_readdir>) but additionally tries to 755Scans a directory (similar to C<aio_readdir>) but additionally tries to
441efficiently separate the entries of directory C<$path> into two sets of 756efficiently separate the entries of directory C<$path> into two sets of
… …
460 775
461Implementation notes. 776Implementation notes.
462 777
463The 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.
464 779
780If readdir returns file type information, then this is used directly to
781find directories.
782
465After reading the directory, the modification time, size etc. of the 783Otherwise, after reading the directory, the modification time, size etc.
466directory 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
467isn'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
468entries are directories (if >= 2). Otherwise, no knowledge of the number 786how many entries are directories (if >= 2). Otherwise, no knowledge of the
469of subdirectories will be assumed. 787number of subdirectories will be assumed.
470 788
471Then entries will be sorted into likely directories (everything without 789Then entries will be sorted into likely directories a non-initial dot
472a non-initial dot currently) and likely non-directories (everything 790currently) and likely non-directories (see C<aio_readdirx>). Then every
473else). 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,
474likely directories first. If that succeeds, it assumes that the entry 792in order of their inode numbers. If that succeeds, it assumes that the
475is a directory or a symlink to directory (which will be checked 793entry is a directory or a symlink to directory (which will be checked
476seperately). This is often faster than stat'ing the entry itself because 794seperately). This is often faster than stat'ing the entry itself because
477filesystems might detect the type of the entry without reading the inode 795filesystems might detect the type of the entry without reading the inode
478data (e.g. ext2fs filetype feature). 796data (e.g. ext2fs filetype feature), even on systems that cannot return
797the filetype information on readdir.
479 798
480If 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
481rest of the entries is assumed to be non-directories. 800rest of the entries is assumed to be non-directories.
482 801
483This only works with certainty on POSIX (= UNIX) filesystems, which 802This only works with certainty on POSIX (= UNIX) filesystems, which
… …
487as 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
488directory counting heuristic. 807directory counting heuristic.
489 808
490=cut 809=cut
491 810
492sub aio_scandir($$$) { 811sub aio_scandir($$;$) {
493 my ($path, $maxreq, $cb) = @_; 812 my ($path, $maxreq, $cb) = @_;
494 813
495 my $pri = aioreq_pri; 814 my $pri = aioreq_pri;
496 815
497 my $grp = aio_group $cb; 816 my $grp = aio_group $cb;
… …
505 my $now = time; 824 my $now = time;
506 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 825 my $hash1 = join ":", (stat _)[0,1,3,7,9];
507 826
508 # read the directory entries 827 # read the directory entries
509 aioreq_pri $pri; 828 aioreq_pri $pri;
510 add $grp aio_readdir $path, sub { 829 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
511 my $entries = shift 830 my $entries = shift
512 or return $grp->result (); 831 or return $grp->result ();
513 832
514 # stat the dir another time 833 # stat the dir another time
515 aioreq_pri $pri; 834 aioreq_pri $pri;
… …
521 # take the slow route if anything looks fishy 840 # take the slow route if anything looks fishy
522 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 841 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523 $ndirs = -1; 842 $ndirs = -1;
524 } else { 843 } else {
525 # if nlink == 2, we are finished 844 # if nlink == 2, we are finished
526 # on non-posix-fs's, we rely on nlink < 2 845 # for non-posix-fs's, we rely on nlink < 2
527 $ndirs = (stat _)[3] - 2 846 $ndirs = (stat _)[3] - 2
528 or return $grp->result ([], $entries); 847 or return $grp->result ([], $entries);
529 } 848 }
530 849
531 # sort into likely dirs and likely nondirs
532 # dirs == files without ".", short entries first
533 $entries = [map $_->[0],
534 sort { $b->[1] cmp $a->[1] }
535 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
536 @$entries];
537
538 my (@dirs, @nondirs); 850 my (@dirs, @nondirs);
539 851
540 my $statgrp = add $grp aio_group sub { 852 my $statgrp = add $grp aio_group sub {
541 $grp->result (\@dirs, \@nondirs); 853 $grp->result (\@dirs, \@nondirs);
542 }; 854 };
543 855
544 limit $statgrp $maxreq; 856 limit $statgrp $maxreq;
545 feed $statgrp sub { 857 feed $statgrp sub {
546 return unless @$entries; 858 return unless @$entries;
547 my $entry = pop @$entries; 859 my $entry = shift @$entries;
548 860
549 aioreq_pri $pri; 861 aioreq_pri $pri;
550 add $statgrp aio_stat "$path/$entry/.", sub { 862 add $statgrp aio_stat "$path/$entry/.", sub {
551 if ($_[0] < 0) { 863 if ($_[0] < 0) {
552 push @nondirs, $entry; 864 push @nondirs, $entry;
… …
573 }; 885 };
574 886
575 $grp 887 $grp
576} 888}
577 889
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
578=item aio_fsync $fh, $callback->($status) 929=item aio_fsync $fh, $callback->($status)
579 930
580Asynchronously call fsync on the given filehandle and call the callback 931Asynchronously call fsync on the given filehandle and call the callback
581with the fsync result code. 932with the fsync result code.
582 933
… …
585Asynchronously call fdatasync on the given filehandle and call the 936Asynchronously call fdatasync on the given filehandle and call the
586callback with the fdatasync result code. 937callback with the fdatasync result code.
587 938
588If 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
589detected, 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}
590 991
591=item aio_group $callback->(...) 992=item aio_group $callback->(...)
592 993
593This 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
594container 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
… …
644=item cancel $req 1045=item cancel $req
645 1046
646Cancels the request, if possible. Has the effect of skipping execution 1047Cancels the request, if possible. Has the effect of skipping execution
647when entering the B<execute> state and skipping calling the callback when 1048when entering the B<execute> state and skipping calling the callback when
648entering the the B<result> state, but will leave the request otherwise 1049entering the the B<result> state, but will leave the request otherwise
649untouched. That means that requests that currently execute will not be 1050untouched (with the exception of readdir). That means that requests that
650stopped 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.
651 1053
652=item cb $req $callback->(...) 1054=item cb $req $callback->(...)
653 1055
654Replace (or simply set) the callback registered to the request. 1056Replace (or simply set) the callback registered to the request.
655 1057
… …
706Their lifetime, simplified, looks like this: when they are empty, they 1108Their lifetime, simplified, looks like this: when they are empty, they
707will 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
708C<done> state, they will also finish. Otherwise they will continue to 1110C<done> state, they will also finish. Otherwise they will continue to
709exist. 1111exist.
710 1112
711That 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
712in 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
713group. 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
714itself finish. 1116further requests to the group. And only when all those requests have
1117finished will the the group itself finish.
715 1118
716=over 4 1119=over 4
717 1120
718=item add $grp ... 1121=item add $grp ...
719 1122
… …
731itself. 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.
732 1135
733=item $grp->result (...) 1136=item $grp->result (...)
734 1137
735Set 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
736subrequests have finished and set thre groups errno to the current value 1139subrequests have finished and set the groups errno to the current value
737of errno (just like calling C<errno> without an error number). By default, 1140of errno (just like calling C<errno> without an error number). By default,
738no argument will be passed and errno is zero. 1141no argument will be passed and errno is zero.
739 1142
740=item $grp->errno ([$errno]) 1143=item $grp->errno ([$errno])
741 1144
… …
752=item feed $grp $callback->($grp) 1155=item feed $grp $callback->($grp)
753 1156
754Sets 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
755generator that generates requests if idle. The idea behind this is that, 1158generator that generates requests if idle. The idea behind this is that,
756although 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,
757this might starve other requests for a potentially long time. For 1160this might starve other requests for a potentially long time. For example,
758example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> 1161C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
759requests, delaying any later requests for a long time. 1162delaying any later requests for a long time.
760 1163
761To avoid this, and allow incremental generation of requests, you can 1164To avoid this, and allow incremental generation of requests, you can
762instead 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
763feed 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>,
764below) 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
… …
768not impose any limits). 1171not impose any limits).
769 1172
770If 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
771automatically removed from the group. 1174automatically removed from the group.
772 1175
773If 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.
774 1178
775Example: 1179Example:
776 1180
777 # 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:
778 1182
… …
790Sets 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
791the group contains less than this many requests. 1195the group contains less than this many requests.
792 1196
793Setting the limit to C<0> will pause the feeding process. 1197Setting the limit to C<0> will pause the feeding process.
794 1198
1199The default value for the limit is C<0>, but note that setting a feeder
1200automatically bumps it up to C<2>.
1201
795=back 1202=back
796 1203
797=head2 SUPPORT FUNCTIONS 1204=head2 SUPPORT FUNCTIONS
1205
1206=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
798 1207
799=over 4 1208=over 4
800 1209
801=item $fileno = IO::AIO::poll_fileno 1210=item $fileno = IO::AIO::poll_fileno
802 1211
… …
807 1216
808See C<poll_cb> for an example. 1217See C<poll_cb> for an example.
809 1218
810=item IO::AIO::poll_cb 1219=item IO::AIO::poll_cb
811 1220
812Process 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
813regularly. Returns the number of events processed. Returns immediately 1222regularly. Returns C<0> if all events could be processed, or C<-1> if it
814when 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>.
815 1226
816If not all requests were processed for whatever reason, the filehandle 1227If not all requests were processed for whatever reason, the filehandle
817will still be ready when C<poll_cb> returns. 1228will still be ready when C<poll_cb> returns, so normally you don't have to
1229do anything special to have it called later.
818 1230
819Example: Install an Event watcher that automatically calls 1231Example: Install an Event watcher that automatically calls
820IO::AIO::poll_cb with high priority: 1232IO::AIO::poll_cb with high priority:
821 1233
822 Event->io (fd => IO::AIO::poll_fileno, 1234 Event->io (fd => IO::AIO::poll_fileno,
823 poll => 'r', async => 1, 1235 poll => 'r', async => 1,
824 cb => \&IO::AIO::poll_cb); 1236 cb => \&IO::AIO::poll_cb);
825 1237
826=item IO::AIO::poll_some $max_requests 1238=item IO::AIO::max_poll_reqs $nreqs
827 1239
828Similar to C<poll_cb>, but only processes up to C<$max_requests> requests 1240=item IO::AIO::max_poll_time $seconds
829at a time.
830 1241
831Useful if you want to ensure some level of interactiveness when perl is 1242These set the maximum number of requests (default C<0>, meaning infinity)
832not 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.
833 1258
834Example: Install an Event watcher that automatically calls 1259Example: Install an Event watcher that automatically calls
835IO::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
836program get the CPU sometimes even under high AIO load. 1261program get the CPU sometimes even under high AIO load.
837 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
838 Event->io (fd => IO::AIO::poll_fileno, 1267 Event->io (fd => IO::AIO::poll_fileno,
839 poll => 'r', nice => 1, 1268 poll => 'r', nice => 1,
840 cb => sub { IO::AIO::poll_some 256 }); 1269 cb => &IO::AIO::poll_cb);
841 1270
842=item IO::AIO::poll_wait 1271=item IO::AIO::poll_wait
843 1272
1273If there are any outstanding requests and none of them in the result
844Wait till the result filehandle becomes ready for reading (simply does a 1274phase, wait till the result filehandle becomes ready for reading (simply
845C<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
846for some requests to finish). 1276synchronously wait for some requests to finish).
847 1277
848See C<nreqs> for an example. 1278See C<nreqs> for an example.
849 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
850=item IO::AIO::nreqs 1289=item IO::AIO::flush
851 1290
852Returns the number of requests currently in the ready, execute or pending 1291Wait till all outstanding AIO requests have been handled.
853states (i.e. for which their callback has not been invoked yet).
854 1292
855Example: wait till there are no outstanding requests anymore: 1293Strictly equivalent to:
856 1294
857 IO::AIO::poll_wait, IO::AIO::poll_cb 1295 IO::AIO::poll_wait, IO::AIO::poll_cb
858 while IO::AIO::nreqs; 1296 while IO::AIO::nreqs;
859 1297
860=item IO::AIO::nready 1298=back
861 1299
862Returns the number of requests currently in the ready state (not yet 1300=head3 CONTROLLING THE NUMBER OF THREADS
863executed).
864 1301
865=item IO::AIO::npending 1302=over
866
867Returns the number of requests currently in the pending state (executed,
868but not yet processed by poll_cb).
869
870=item IO::AIO::flush
871
872Wait till all outstanding AIO requests have been handled.
873
874Strictly equivalent to:
875
876 IO::AIO::poll_wait, IO::AIO::poll_cb
877 while IO::AIO::nreqs;
878
879=item IO::AIO::poll
880
881Waits until some requests have been handled.
882
883Strictly equivalent to:
884
885 IO::AIO::poll_wait, IO::AIO::poll_cb
886 if IO::AIO::nreqs;
887 1303
888=item IO::AIO::min_parallel $nthreads 1304=item IO::AIO::min_parallel $nthreads
889 1305
890Set the minimum number of AIO threads to C<$nthreads>. The current 1306Set the minimum number of AIO threads to C<$nthreads>. The current
891default is C<8>, which means eight asynchronous operations can execute 1307default is C<8>, which means eight asynchronous operations can execute
892concurrently at any one time (the number of outstanding requests, 1308concurrently at any one time (the number of outstanding requests,
893however, is unlimited). 1309however, is unlimited).
894 1310
895IO::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
896no 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.
897 1315
898It 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
899Linux kernel versions will scale negatively with the number of threads 1317Linux kernel versions will scale negatively with the number of threads
900(higher parallelity => MUCH higher latency). With current Linux 2.6 1318(higher parallelity => MUCH higher latency). With current Linux 2.6
901versions, 4-32 threads should be fine. 1319versions, 4-32 threads should be fine.
… …
915This 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
916that all threads are killed and that there are no outstanding requests. 1334that all threads are killed and that there are no outstanding requests.
917 1335
918Under normal circumstances you don't need to call this function. 1336Under normal circumstances you don't need to call this function.
919 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
920=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1353=item IO::AIO::max_outstanding $maxreqs
921 1354
922This is a very bad function to use in interactive programs because it 1355This is a very bad function to use in interactive programs because it
923blocks, and a bad way to reduce concurrency because it is inexact: Better 1356blocks, and a bad way to reduce concurrency because it is inexact: Better
924use an C<aio_group> together with a feed callback. 1357use an C<aio_group> together with a feed callback.
925 1358
926Sets the maximum number of outstanding requests to C<$nreqs>. If you 1359Sets the maximum number of outstanding requests to C<$nreqs>. If you
927to queue up more than this number of requests, the next call to the 1360do queue up more than this number of requests, the next call to the
928C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>) 1361C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
929function will block until the limit is no longer exceeded. 1362function will block until the limit is no longer exceeded.
930 1363
931The default value is very large, so there is no practical limit on the 1364The default value is very large, so there is no practical limit on the
932number of outstanding requests. 1365number of outstanding requests.
933 1366
934You can still queue as many requests as you want. Therefore, 1367You can still queue as many requests as you want. Therefore,
935C<max_oustsanding> is mainly useful in simple scripts (with low values) or 1368C<max_outstanding> is mainly useful in simple scripts (with low values) or
936as a stop gap to shield against fatal memory overflow (with large values). 1369as a stop gap to shield against fatal memory overflow (with large values).
937 1370
938=back 1371=back
939 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
940=cut 1399=cut
941 1400
942# support function to convert a fd into a perl filehandle
943sub _fd2fh {
944 return undef if $_[0] < 0;
945
946 # try to generate nice filehandles
947 my $sym = "IO::AIO::fd#$_[0]";
948 local *$sym;
949
950 open *$sym, "+<&=$_[0]" # usually works under any unix
951 or open *$sym, "<&=$_[0]" # cygwin needs this
952 or open *$sym, ">&=$_[0]" # or this
953 or return undef;
954
955 *$sym
956}
957
958min_parallel 8; 1401min_parallel 8;
1402
1403END { flush }
959 1404
9601; 14051;
961 1406
962=head2 FORK BEHAVIOUR 1407=head2 FORK BEHAVIOUR
963 1408
… …
983bytes of memory. In addition, stat requests need a stat buffer (possibly 1428bytes of memory. In addition, stat requests need a stat buffer (possibly
984a 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
985scalars 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
986will consume memory till the request has entered the done state. 1431will consume memory till the request has entered the done state.
987 1432
988This 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
989problem. 1434problem.
990 1435
991Per-thread usage: 1436Per-thread usage:
992 1437
993In the execution phase, some aio requests require more memory for 1438In the execution phase, some aio requests require more memory for
… …
998 1443
999Known bugs will be fixed in the next release. 1444Known bugs will be fixed in the next release.
1000 1445
1001=head1 SEE ALSO 1446=head1 SEE ALSO
1002 1447
1003L<Coro::AIO>. 1448L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1449more natural syntax.
1004 1450
1005=head1 AUTHOR 1451=head1 AUTHOR
1006 1452
1007 Marc Lehmann <schmorp@schmorp.de> 1453 Marc Lehmann <schmorp@schmorp.de>
1008 http://home.schmorp.de/ 1454 http://home.schmorp.de/

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