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Revision 1.109 by root, Sun Jun 3 09:44:17 2007 UTC

… …
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
9 aio_open "/etc/passwd", O_RDONLY, 0, sub { 9 aio_open "/etc/passwd", O_RDONLY, 0, sub {
10 my ($fh) = @_; 10 my $fh = shift
11 or die "/etc/passwd: $!";
11 ... 12 ...
12 }; 13 };
13 14
14 aio_unlink "/tmp/file", sub { }; 15 aio_unlink "/tmp/file", sub { };
15 16
… …
50 51
51=head1 DESCRIPTION 52=head1 DESCRIPTION
52 53
53This module implements asynchronous I/O using whatever means your 54This module implements asynchronous I/O using whatever means your
54operating system supports. 55operating system supports.
56
57Asynchronous means that operations that can normally block your program
58(e.g. reading from disk) will be done asynchronously: the operation
59will still block, but you can do something else in the meantime. This
60is extremely useful for programs that need to stay interactive even
61when doing heavy I/O (GUI programs, high performance network servers
62etc.), but can also be used to easily do operations in parallel that are
63normally done sequentially, e.g. stat'ing many files, which is much faster
64on a RAID volume or over NFS when you do a number of stat operations
65concurrently.
66
67While most of this works on all types of file descriptors (for
68example sockets), using these functions on file descriptors that
69support nonblocking operation (again, sockets, pipes etc.) is very
70inefficient. Use an event loop for that (such as the L<Event|Event>
71module): IO::AIO will naturally fit into such an event loop itself.
55 72
56In this version, a number of threads are started that execute your 73In this version, a number of threads are started that execute your
57requests and signal their completion. You don't need thread support 74requests and signal their completion. You don't need thread support
58in perl, and the threads created by this module will not be visible 75in perl, and the threads created by this module will not be visible
59to perl. In the future, this module might make use of the native aio 76to perl. In the future, this module might make use of the native aio
60functions available on many operating systems. However, they are often 77functions available on many operating systems. However, they are often
61not well-supported or restricted (Linux doesn't allow them on normal 78not well-supported or restricted (GNU/Linux doesn't allow them on normal
62files currently, for example), and they would only support aio_read and 79files currently, for example), and they would only support aio_read and
63aio_write, so the remaining functionality would have to be implemented 80aio_write, so the remaining functionality would have to be implemented
64using threads anyway. 81using threads anyway.
65 82
66Although the module will work with in the presence of other (Perl-) 83Although the module will work in the presence of other (Perl-) threads,
67threads, it is currently not reentrant in any way, so use appropriate 84it is currently not reentrant in any way, so use appropriate locking
68locking yourself, always call C<poll_cb> from within the same thread, or 85yourself, always call C<poll_cb> from within the same thread, or never
69never call C<poll_cb> (or other C<aio_> functions) recursively. 86call C<poll_cb> (or other C<aio_> functions) recursively.
87
88=head2 EXAMPLE
89
90This is a simple example that uses the Event module and loads
91F</etc/passwd> asynchronously:
92
93 use Fcntl;
94 use Event;
95 use IO::AIO;
96
97 # register the IO::AIO callback with Event
98 Event->io (fd => IO::AIO::poll_fileno,
99 poll => 'r',
100 cb => \&IO::AIO::poll_cb);
101
102 # queue the request to open /etc/passwd
103 aio_open "/etc/passwd", O_RDONLY, 0, sub {
104 my $fh = shift
105 or die "error while opening: $!";
106
107 # stat'ing filehandles is generally non-blocking
108 my $size = -s $fh;
109
110 # queue a request to read the file
111 my $contents;
112 aio_read $fh, 0, $size, $contents, 0, sub {
113 $_[0] == $size
114 or die "short read: $!";
115
116 close $fh;
117
118 # file contents now in $contents
119 print $contents;
120
121 # exit event loop and program
122 Event::unloop;
123 };
124 };
125
126 # possibly queue up other requests, or open GUI windows,
127 # check for sockets etc. etc.
128
129 # process events as long as there are some:
130 Event::loop;
70 131
71=head1 REQUEST ANATOMY AND LIFETIME 132=head1 REQUEST ANATOMY AND LIFETIME
72 133
73Every C<aio_*> function creates a request. which is a C data structure not 134Every C<aio_*> function creates a request. which is a C data structure not
74directly visible to Perl. 135directly visible to Perl.
… …
116Request has reached the end of its lifetime and holds no resources anymore 177Request has reached the end of its lifetime and holds no resources anymore
117(except possibly for the Perl object, but its connection to the actual 178(except possibly for the Perl object, but its connection to the actual
118aio request is severed and calling its methods will either do nothing or 179aio request is severed and calling its methods will either do nothing or
119result in a runtime error). 180result in a runtime error).
120 181
182=back
183
121=cut 184=cut
122 185
123package IO::AIO; 186package IO::AIO;
124 187
125no warnings; 188no warnings;
126use strict 'vars'; 189use strict 'vars';
127 190
128use base 'Exporter'; 191use base 'Exporter';
129 192
130BEGIN { 193BEGIN {
131 our $VERSION = '2.0'; 194 our $VERSION = '2.4';
132 195
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 196 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
134 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 197 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
135 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move 198 aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
136 aio_group aio_nop); 199 aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
200 aio_chown aio_chmod aio_utime);
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 201 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 202 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel max_outstanding nreqs); 203 min_parallel max_parallel max_idle
204 nreqs nready npending nthreads
205 max_poll_time max_poll_reqs);
140 206
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 207 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 208
143 require XSLoader; 209 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 210 XSLoader::load ("IO::AIO", $VERSION);
145} 211}
146 212
147=head1 FUNCTIONS 213=head1 FUNCTIONS
148 214
149=head2 AIO FUNCTIONS 215=head2 AIO REQUEST FUNCTIONS
150 216
151All the C<aio_*> calls are more or less thin wrappers around the syscall 217All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 218with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 219and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 220which must be a code reference. This code reference will get called with
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157syscall has been executed asynchronously. 223syscall has been executed asynchronously.
158 224
159All functions expecting a filehandle keep a copy of the filehandle 225All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 226internally until the request has finished.
161 227
162All requests return objects of type L<IO::AIO::REQ> that allow further 228All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 229further manipulation of those requests while they are in-flight.
164 230
165The pathnames you pass to these routines I<must> be absolute and 231The pathnames you pass to these routines I<must> be absolute and
166encoded in byte form. The reason for the former is that at the time the 232encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 233request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 234changed. Alternatively, you can make sure that you never change the
169current working directory. 235current working directory anywhere in the program and then use relative
236paths.
170 237
171To encode pathnames to byte form, either make sure you either: a) 238To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 239in filenames you got from outside (command line, readdir etc.) without
173etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode 240tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174your pathnames to the locale (or other) encoding in effect in the user 241your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 242environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 243use something else to ensure your scalar has the correct contents.
244
245This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246handles correctly wether it is set or not.
177 247
178=over 4 248=over 4
179 249
180=item aioreq_pri $pri 250=item $prev_pri = aioreq_pri [$pri]
181 251
182Sets the priority for the next aio request. The default priority 252Returns the priority value that would be used for the next request and, if
253C<$pri> is given, sets the priority for the next aio request.
254
183is C<0>, the minimum and maximum priorities are C<-4> and C<4>, 255The default priority is C<0>, the minimum and maximum priorities are C<-4>
184respectively. Requests with higher priority will be serviced first. 256and C<4>, respectively. Requests with higher priority will be serviced
257first.
185 258
186The priority will be reset to C<0> after each call to one of the C<aio_> 259The priority will be reset to C<0> after each call to one of the C<aio_*>
187functions. 260functions.
188 261
189Example: open a file with low priority, then read something from it with 262Example: open a file with low priority, then read something from it with
190higher priority so the read request is serviced before other low priority 263higher priority so the read request is serviced before other low priority
191open requests (potentially spamming the cache): 264open requests (potentially spamming the cache):
… …
198 aio_read $_[0], ..., sub { 271 aio_read $_[0], ..., sub {
199 ... 272 ...
200 }; 273 };
201 }; 274 };
202 275
276
203=item aioreq_nice $pri_adjust 277=item aioreq_nice $pri_adjust
204 278
205Similar to C<aioreq_pri>, but subtracts the given value from the current 279Similar to C<aioreq_pri>, but subtracts the given value from the current
206priority, so effects are cumulative. 280priority, so the effect is cumulative.
281
207 282
208=item aio_open $pathname, $flags, $mode, $callback->($fh) 283=item aio_open $pathname, $flags, $mode, $callback->($fh)
209 284
210Asynchronously open or create a file and call the callback with a newly 285Asynchronously open or create a file and call the callback with a newly
211created filehandle for the file. 286created filehandle for the file.
… …
217list. They are the same as used by C<sysopen>. 292list. They are the same as used by C<sysopen>.
218 293
219Likewise, C<$mode> specifies the mode of the newly created file, if it 294Likewise, C<$mode> specifies the mode of the newly created file, if it
220didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, 295didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
221except that it is mandatory (i.e. use C<0> if you don't create new files, 296except that it is mandatory (i.e. use C<0> if you don't create new files,
222and C<0666> or C<0777> if you do). 297and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
298by the umask in effect then the request is being executed, so better never
299change the umask.
223 300
224Example: 301Example:
225 302
226 aio_open "/etc/passwd", O_RDONLY, 0, sub { 303 aio_open "/etc/passwd", O_RDONLY, 0, sub {
227 if ($_[0]) { 304 if ($_[0]) {
… …
230 } else { 307 } else {
231 die "open failed: $!\n"; 308 die "open failed: $!\n";
232 } 309 }
233 }; 310 };
234 311
312
235=item aio_close $fh, $callback->($status) 313=item aio_close $fh, $callback->($status)
236 314
237Asynchronously close a file and call the callback with the result 315Asynchronously close a file and call the callback with the result
238code. I<WARNING:> although accepted, you should not pass in a perl 316code. I<WARNING:> although accepted, you should not pass in a perl
239filehandle here, as perl will likely close the file descriptor another 317filehandle here, as perl will likely close the file descriptor another
… …
241C<close> or just let filehandles go out of scope. 319C<close> or just let filehandles go out of scope.
242 320
243This is supposed to be a bug in the API, so that might change. It's 321This is supposed to be a bug in the API, so that might change. It's
244therefore best to avoid this function. 322therefore best to avoid this function.
245 323
324
246=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 325=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
247 326
248=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 327=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
249 328
250Reads or writes C<length> bytes from the specified C<fh> and C<offset> 329Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
251into the scalar given by C<data> and offset C<dataoffset> and calls the 330into the scalar given by C<$data> and offset C<$dataoffset> and calls the
252callback without the actual number of bytes read (or -1 on error, just 331callback without the actual number of bytes read (or -1 on error, just
253like the syscall). 332like the syscall).
254 333
334If C<$offset> is undefined, then the current file offset will be used (and
335updated), otherwise the file offset will not be changed by these calls.
336
337If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
338
339If C<$dataoffset> is less than zero, it will be counted from the end of
340C<$data>.
341
255The C<$data> scalar I<MUST NOT> be modified in any way while the request 342The C<$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 343is outstanding. Modifying it can result in segfaults or World War III (if
257necessary/optional hardware is installed). 344the necessary/optional hardware is installed).
258 345
259Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 346Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
260offset C<0> within the scalar: 347offset C<0> within the scalar:
261 348
262 aio_read $fh, 7, 15, $buffer, 0, sub { 349 aio_read $fh, 7, 15, $buffer, 0, sub {
263 $_[0] > 0 or die "read error: $!"; 350 $_[0] > 0 or die "read error: $!";
264 print "read $_[0] bytes: <$buffer>\n"; 351 print "read $_[0] bytes: <$buffer>\n";
265 }; 352 };
266 353
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}
334 354
335=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 355=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
336 356
337Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 357Tries 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 358reading 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 372C<$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 373bytes 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 374provides 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 375value equals C<$length> one can assume that C<$length> bytes have been
356read. 376read.
377
357 378
358=item aio_readahead $fh,$offset,$length, $callback->($retval) 379=item aio_readahead $fh,$offset,$length, $callback->($retval)
359 380
360C<aio_readahead> populates the page cache with data from a file so that 381C<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> 382subsequent 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. 388file. The current file offset of the file is left unchanged.
368 389
369If that syscall doesn't exist (likely if your OS isn't Linux) it will be 390If 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. 391emulated by simply reading the data, which would have a similar effect.
371 392
393
372=item aio_stat $fh_or_path, $callback->($status) 394=item aio_stat $fh_or_path, $callback->($status)
373 395
374=item aio_lstat $fh, $callback->($status) 396=item aio_lstat $fh, $callback->($status)
375 397
376Works like perl's C<stat> or C<lstat> in void context. The callback will 398Works like perl's C<stat> or C<lstat> in void context. The callback will
… …
389 aio_stat "/etc/passwd", sub { 411 aio_stat "/etc/passwd", sub {
390 $_[0] and die "stat failed: $!"; 412 $_[0] and die "stat failed: $!";
391 print "size is ", -s _, "\n"; 413 print "size is ", -s _, "\n";
392 }; 414 };
393 415
416
417=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
418
419Works like perl's C<utime> function (including the special case of $atime
420and $mtime being undef). Fractional times are supported if the underlying
421syscalls support them.
422
423When called with a pathname, uses utimes(2) if available, otherwise
424utime(2). If called on a file descriptor, uses futimes(2) if available,
425otherwise returns ENOSYS, so this is not portable.
426
427Examples:
428
429 # set atime and mtime to current time (basically touch(1)):
430 aio_utime "path", undef, undef;
431 # set atime to current time and mtime to beginning of the epoch:
432 aio_utime "path", time, undef; # undef==0
433
434
435=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
436
437Works like perl's C<chown> function, except that C<undef> for either $uid
438or $gid is being interpreted as "do not change" (but -1 can also be used).
439
440Examples:
441
442 # same as "chown root path" in the shell:
443 aio_chown "path", 0, -1;
444 # same as above:
445 aio_chown "path", 0, undef;
446
447
448=item aio_chmod $fh_or_path, $mode, $callback->($status)
449
450Works like perl's C<chmod> function.
451
452
394=item aio_unlink $pathname, $callback->($status) 453=item aio_unlink $pathname, $callback->($status)
395 454
396Asynchronously unlink (delete) a file and call the callback with the 455Asynchronously unlink (delete) a file and call the callback with the
397result code. 456result code.
398 457
458
459=item aio_mknod $path, $mode, $dev, $callback->($status)
460
461[EXPERIMENTAL]
462
463Asynchronously create a device node (or fifo). See mknod(2).
464
465The only (POSIX-) portable way of calling this function is:
466
467 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
468
469
399=item aio_link $srcpath, $dstpath, $callback->($status) 470=item aio_link $srcpath, $dstpath, $callback->($status)
400 471
401Asynchronously create a new link to the existing object at C<$srcpath> at 472Asynchronously create a new link to the existing object at C<$srcpath> at
402the path C<$dstpath> and call the callback with the result code. 473the path C<$dstpath> and call the callback with the result code.
403 474
475
404=item aio_symlink $srcpath, $dstpath, $callback->($status) 476=item aio_symlink $srcpath, $dstpath, $callback->($status)
405 477
406Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 478Asynchronously 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. 479the path C<$dstpath> and call the callback with the result code.
408 480
481
482=item aio_readlink $path, $callback->($link)
483
484Asynchronously read the symlink specified by C<$path> and pass it to
485the callback. If an error occurs, nothing or undef gets passed to the
486callback.
487
488
409=item aio_rename $srcpath, $dstpath, $callback->($status) 489=item aio_rename $srcpath, $dstpath, $callback->($status)
410 490
411Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 491Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
412rename(2) and call the callback with the result code. 492rename(2) and call the callback with the result code.
413 493
494
495=item aio_mkdir $pathname, $mode, $callback->($status)
496
497Asynchronously mkdir (create) a directory and call the callback with
498the result code. C<$mode> will be modified by the umask at the time the
499request is executed, so do not change your umask.
500
501
414=item aio_rmdir $pathname, $callback->($status) 502=item aio_rmdir $pathname, $callback->($status)
415 503
416Asynchronously rmdir (delete) a directory and call the callback with the 504Asynchronously rmdir (delete) a directory and call the callback with the
417result code. 505result code.
506
418 507
419=item aio_readdir $pathname, $callback->($entries) 508=item aio_readdir $pathname, $callback->($entries)
420 509
421Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 510Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
422directory (i.e. opendir + readdir + closedir). The entries will not be 511directory (i.e. opendir + readdir + closedir). The entries will not be
423sorted, and will B<NOT> include the C<.> and C<..> entries. 512sorted, and will B<NOT> include the C<.> and C<..> entries.
424 513
425The callback a single argument which is either C<undef> or an array-ref 514The callback a single argument which is either C<undef> or an array-ref
426with the filenames. 515with the filenames.
427 516
517
518=item aio_load $path, $data, $callback->($status)
519
520This is a composite request that tries to fully load the given file into
521memory. Status is the same as with aio_read.
522
523=cut
524
525sub aio_load($$;$) {
526 aio_block {
527 my ($path, undef, $cb) = @_;
528 my $data = \$_[1];
529
530 my $pri = aioreq_pri;
531 my $grp = aio_group $cb;
532
533 aioreq_pri $pri;
534 add $grp aio_open $path, O_RDONLY, 0, sub {
535 my $fh = shift
536 or return $grp->result (-1);
537
538 aioreq_pri $pri;
539 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
540 $grp->result ($_[0]);
541 };
542 };
543
544 $grp
545 }
546}
547
548=item aio_copy $srcpath, $dstpath, $callback->($status)
549
550Try to copy the I<file> (directories not supported as either source or
551destination) from C<$srcpath> to C<$dstpath> and call the callback with
552the C<0> (error) or C<-1> ok.
553
554This is a composite request that it creates the destination file with
555mode 0200 and copies the contents of the source file into it using
556C<aio_sendfile>, followed by restoring atime, mtime, access mode and
557uid/gid, in that order.
558
559If an error occurs, the partial destination file will be unlinked, if
560possible, except when setting atime, mtime, access mode and uid/gid, where
561errors are being ignored.
562
563=cut
564
565sub aio_copy($$;$) {
566 aio_block {
567 my ($src, $dst, $cb) = @_;
568
569 my $pri = aioreq_pri;
570 my $grp = aio_group $cb;
571
572 aioreq_pri $pri;
573 add $grp aio_open $src, O_RDONLY, 0, sub {
574 if (my $src_fh = $_[0]) {
575 my @stat = stat $src_fh;
576
577 aioreq_pri $pri;
578 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
579 if (my $dst_fh = $_[0]) {
580 aioreq_pri $pri;
581 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
582 if ($_[0] == $stat[7]) {
583 $grp->result (0);
584 close $src_fh;
585
586 # those should not normally block. should. should.
587 utime $stat[8], $stat[9], $dst;
588 chmod $stat[2] & 07777, $dst_fh;
589 chown $stat[4], $stat[5], $dst_fh;
590 close $dst_fh;
591 } else {
592 $grp->result (-1);
593 close $src_fh;
594 close $dst_fh;
595
596 aioreq $pri;
597 add $grp aio_unlink $dst;
598 }
599 };
600 } else {
601 $grp->result (-1);
602 }
603 },
604
605 } else {
606 $grp->result (-1);
607 }
608 };
609
610 $grp
611 }
612}
613
614=item aio_move $srcpath, $dstpath, $callback->($status)
615
616Try to move the I<file> (directories not supported as either source or
617destination) from C<$srcpath> to C<$dstpath> and call the callback with
618the C<0> (error) or C<-1> ok.
619
620This is a composite request that tries to rename(2) the file first. If
621rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
622that is successful, unlinking the C<$srcpath>.
623
624=cut
625
626sub aio_move($$;$) {
627 aio_block {
628 my ($src, $dst, $cb) = @_;
629
630 my $pri = aioreq_pri;
631 my $grp = aio_group $cb;
632
633 aioreq_pri $pri;
634 add $grp aio_rename $src, $dst, sub {
635 if ($_[0] && $! == EXDEV) {
636 aioreq_pri $pri;
637 add $grp aio_copy $src, $dst, sub {
638 $grp->result ($_[0]);
639
640 if (!$_[0]) {
641 aioreq_pri $pri;
642 add $grp aio_unlink $src;
643 }
644 };
645 } else {
646 $grp->result ($_[0]);
647 }
648 };
649
650 $grp
651 }
652}
653
428=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 654=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429 655
430Scans a directory (similar to C<aio_readdir>) but additionally tries to 656Scans a directory (similar to C<aio_readdir>) but additionally tries to
431separate the entries of directory C<$path> into two sets of names, ones 657efficiently separate the entries of directory C<$path> into two sets of
432you can recurse into (directories or links to them), and ones you cannot 658names, directories you can recurse into (directories), and ones you cannot
433recurse into (everything else). 659recurse into (everything else, including symlinks to directories).
434 660
435C<aio_scandir> is a composite request that creates of many sub requests_ 661C<aio_scandir> is a composite request that creates of many sub requests_
436C<$maxreq> specifies the maximum number of outstanding aio requests that 662C<$maxreq> specifies the maximum number of outstanding aio requests that
437this function generates. If it is C<< <= 0 >>, then a suitable default 663this function generates. If it is C<< <= 0 >>, then a suitable default
438will be chosen (currently 6). 664will be chosen (currently 4).
439 665
440On error, the callback is called without arguments, otherwise it receives 666On error, the callback is called without arguments, otherwise it receives
441two array-refs with path-relative entry names. 667two array-refs with path-relative entry names.
442 668
443Example: 669Example:
… …
477as those tend to return 0 or 1 as link counts, which disables the 703as those tend to return 0 or 1 as link counts, which disables the
478directory counting heuristic. 704directory counting heuristic.
479 705
480=cut 706=cut
481 707
482sub aio_scandir($$$) { 708sub aio_scandir($$;$) {
709 aio_block {
483 my ($path, $maxreq, $cb) = @_; 710 my ($path, $maxreq, $cb) = @_;
484 711
712 my $pri = aioreq_pri;
713
485 my $grp = aio_group $cb; 714 my $grp = aio_group $cb;
486 715
487 $maxreq = 6 if $maxreq <= 0; 716 $maxreq = 4 if $maxreq <= 0;
488 717
489 # stat once 718 # stat once
719 aioreq_pri $pri;
490 add $grp aio_stat $path, sub { 720 add $grp aio_stat $path, sub {
491 return $grp->result () if $_[0]; 721 return $grp->result () if $_[0];
492 my $now = time; 722 my $now = time;
493 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 723 my $hash1 = join ":", (stat _)[0,1,3,7,9];
494 724
495 # read the directory entries 725 # read the directory entries
726 aioreq_pri $pri;
496 add $grp aio_readdir $path, sub { 727 add $grp aio_readdir $path, sub {
497 my $entries = shift 728 my $entries = shift
498 or return $grp->result (); 729 or return $grp->result ();
499 730
500 # stat the dir another time 731 # stat the dir another time
732 aioreq_pri $pri;
501 add $grp aio_stat $path, sub { 733 add $grp aio_stat $path, sub {
502 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 734 my $hash2 = join ":", (stat _)[0,1,3,7,9];
503 735
504 my $ndirs; 736 my $ndirs;
505 737
506 # take the slow route if anything looks fishy 738 # take the slow route if anything looks fishy
507 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 739 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508 $ndirs = -1; 740 $ndirs = -1;
509 } else { 741 } else {
510 # if nlink == 2, we are finished 742 # if nlink == 2, we are finished
511 # on non-posix-fs's, we rely on nlink < 2 743 # on non-posix-fs's, we rely on nlink < 2
512 $ndirs = (stat _)[3] - 2 744 $ndirs = (stat _)[3] - 2
513 or return $grp->result ([], $entries); 745 or return $grp->result ([], $entries);
514 } 746 }
515 747
516 # sort into likely dirs and likely nondirs 748 # sort into likely dirs and likely nondirs
517 # dirs == files without ".", short entries first 749 # dirs == files without ".", short entries first
518 $entries = [map $_->[0], 750 $entries = [map $_->[0],
519 sort { $b->[1] cmp $a->[1] } 751 sort { $b->[1] cmp $a->[1] }
520 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], 752 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
521 @$entries]; 753 @$entries];
522 754
523 my (@dirs, @nondirs); 755 my (@dirs, @nondirs);
524 756
525 my ($statcb, $schedcb);
526 my $nreq = 0;
527
528 my $statgrp = add $grp aio_group; 757 my $statgrp = add $grp aio_group sub {
529
530 $schedcb = sub {
531 if (@$entries) {
532 if ($nreq < $maxreq) {
533 my $ent = pop @$entries;
534 $nreq++;
535 add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
536 }
537 } elsif (!$nreq) {
538 # finished
539 $statgrp->cancel;
540 undef $statcb;
541 undef $schedcb;
542 $grp->result (\@dirs, \@nondirs); 758 $grp->result (\@dirs, \@nondirs);
543 } 759 };
760
761 limit $statgrp $maxreq;
762 feed $statgrp sub {
763 return unless @$entries;
764 my $entry = pop @$entries;
765
766 aioreq_pri $pri;
767 add $statgrp aio_stat "$path/$entry/.", sub {
768 if ($_[0] < 0) {
769 push @nondirs, $entry;
770 } else {
771 # need to check for real directory
772 aioreq_pri $pri;
773 add $statgrp aio_lstat "$path/$entry", sub {
774 if (-d _) {
775 push @dirs, $entry;
776
777 unless (--$ndirs) {
778 push @nondirs, @$entries;
779 feed $statgrp;
780 }
781 } else {
782 push @nondirs, $entry;
783 }
784 }
785 }
786 };
787 };
544 }; 788 };
545 $statcb = sub {
546 my ($status, $entry) = @_;
547
548 if ($status < 0) {
549 $nreq--;
550 push @nondirs, $entry;
551 &$schedcb;
552 } else {
553 # need to check for real directory
554 add $grp aio_lstat "$path/$entry", sub {
555 $nreq--;
556
557 if (-d _) {
558 push @dirs, $entry;
559
560 if (!--$ndirs) {
561 push @nondirs, @$entries;
562 $entries = [];
563 }
564 } else {
565 push @nondirs, $entry;
566 }
567
568 &$schedcb;
569 }
570 }
571 };
572
573 &$schedcb while @$entries && $nreq < $maxreq;
574 }; 789 };
575 }; 790 };
791
792 $grp
576 }; 793 }
794}
577 795
796=item aio_rmtree $path, $callback->($status)
797
798Delete a directory tree starting (and including) C<$path>, return the
799status of the final C<rmdir> only. This is a composite request that
800uses C<aio_scandir> to recurse into and rmdir directories, and unlink
801everything else.
802
803=cut
804
805sub aio_rmtree;
806sub aio_rmtree($;$) {
807 aio_block {
808 my ($path, $cb) = @_;
809
810 my $pri = aioreq_pri;
811 my $grp = aio_group $cb;
812
813 aioreq_pri $pri;
814 add $grp aio_scandir $path, 0, sub {
815 my ($dirs, $nondirs) = @_;
816
817 my $dirgrp = aio_group sub {
818 add $grp aio_rmdir $path, sub {
819 $grp->result ($_[0]);
820 };
821 };
822
823 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
824 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
825
826 add $grp $dirgrp;
827 };
828
578 $grp 829 $grp
830 }
579} 831}
580 832
581=item aio_fsync $fh, $callback->($status) 833=item aio_fsync $fh, $callback->($status)
582 834
583Asynchronously call fsync on the given filehandle and call the callback 835Asynchronously call fsync on the given filehandle and call the callback
… …
590 842
591If this call isn't available because your OS lacks it or it couldn't be 843If this call isn't available because your OS lacks it or it couldn't be
592detected, it will be emulated by calling C<fsync> instead. 844detected, it will be emulated by calling C<fsync> instead.
593 845
594=item aio_group $callback->(...) 846=item aio_group $callback->(...)
595
596[EXPERIMENTAL]
597 847
598This is a very special aio request: Instead of doing something, it is a 848This is a very special aio request: Instead of doing something, it is a
599container for other aio requests, which is useful if you want to bundle 849container for other aio requests, which is useful if you want to bundle
600many requests into a single, composite, request with a definite callback 850many requests into a single, composite, request with a definite callback
601and the ability to cancel the whole request with its subrequests. 851and the ability to cancel the whole request with its subrequests.
… …
704=item * They can also can also be added to other IO::AIO::GRP objects. 954=item * They can also can also be added to other IO::AIO::GRP objects.
705 955
706=item * You must not add requests to a group from within the group callback (or 956=item * You must not add requests to a group from within the group callback (or
707any later time). 957any later time).
708 958
709=item * This does not harmonise well with C<max_outstanding>, so best do
710not combine C<aio_group> with it. Groups and feeders are recommended for
711this kind of concurrency-limiting.
712
713=back 959=back
714 960
715Their lifetime, simplified, looks like this: when they are empty, they 961Their lifetime, simplified, looks like this: when they are empty, they
716will finish very quickly. If they contain only requests that are in the 962will finish very quickly. If they contain only requests that are in the
717C<done> state, they will also finish. Otherwise they will continue to 963C<done> state, they will also finish. Otherwise they will continue to
… …
732be added, including other groups, as long as you do not create circular 978be added, including other groups, as long as you do not create circular
733dependencies. 979dependencies.
734 980
735Returns all its arguments. 981Returns all its arguments.
736 982
983=item $grp->cancel_subs
984
985Cancel all subrequests and clears any feeder, but not the group request
986itself. Useful when you queued a lot of events but got a result early.
987
737=item $grp->result (...) 988=item $grp->result (...)
738 989
739Set the result value(s) that will be passed to the group callback when all 990Set the result value(s) that will be passed to the group callback when all
740subrequests have finished. By default, no argument will be passed. 991subrequests have finished and set thre groups errno to the current value
992of errno (just like calling C<errno> without an error number). By default,
993no argument will be passed and errno is zero.
994
995=item $grp->errno ([$errno])
996
997Sets the group errno value to C<$errno>, or the current value of errno
998when the argument is missing.
999
1000Every aio request has an associated errno value that is restored when
1001the callback is invoked. This method lets you change this value from its
1002default (0).
1003
1004Calling C<result> will also set errno, so make sure you either set C<$!>
1005before the call to C<result>, or call c<errno> after it.
741 1006
742=item feed $grp $callback->($grp) 1007=item feed $grp $callback->($grp)
743
744[VERY EXPERIMENTAL]
745 1008
746Sets a feeder/generator on this group: every group can have an attached 1009Sets a feeder/generator on this group: every group can have an attached
747generator that generates requests if idle. The idea behind this is that, 1010generator that generates requests if idle. The idea behind this is that,
748although you could just queue as many requests as you want in a group, 1011although you could just queue as many requests as you want in a group,
749this might starve other requests for a potentially long time. For 1012this might starve other requests for a potentially long time. For
… …
786 1049
787=back 1050=back
788 1051
789=head2 SUPPORT FUNCTIONS 1052=head2 SUPPORT FUNCTIONS
790 1053
1054=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1055
791=over 4 1056=over 4
792 1057
793=item $fileno = IO::AIO::poll_fileno 1058=item $fileno = IO::AIO::poll_fileno
794 1059
795Return the I<request result pipe file descriptor>. This filehandle must be 1060Return the I<request result pipe file descriptor>. This filehandle must be
… …
799 1064
800See C<poll_cb> for an example. 1065See C<poll_cb> for an example.
801 1066
802=item IO::AIO::poll_cb 1067=item IO::AIO::poll_cb
803 1068
804Process all outstanding events on the result pipe. You have to call this 1069Process some outstanding events on the result pipe. You have to call this
805regularly. Returns the number of events processed. Returns immediately 1070regularly. Returns the number of events processed. Returns immediately
806when no events are outstanding. 1071when no events are outstanding. The amount of events processed depends on
1072the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1073
1074If not all requests were processed for whatever reason, the filehandle
1075will still be ready when C<poll_cb> returns.
807 1076
808Example: Install an Event watcher that automatically calls 1077Example: Install an Event watcher that automatically calls
809IO::AIO::poll_cb with high priority: 1078IO::AIO::poll_cb with high priority:
810 1079
811 Event->io (fd => IO::AIO::poll_fileno, 1080 Event->io (fd => IO::AIO::poll_fileno,
812 poll => 'r', async => 1, 1081 poll => 'r', async => 1,
813 cb => \&IO::AIO::poll_cb); 1082 cb => \&IO::AIO::poll_cb);
814 1083
1084=item IO::AIO::max_poll_reqs $nreqs
1085
1086=item IO::AIO::max_poll_time $seconds
1087
1088These set the maximum number of requests (default C<0>, meaning infinity)
1089that are being processed by C<IO::AIO::poll_cb> in one call, respectively
1090the maximum amount of time (default C<0>, meaning infinity) spent in
1091C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
1092of time C<poll_cb> is allowed to use).
1093
1094Setting C<max_poll_time> to a non-zero value creates an overhead of one
1095syscall per request processed, which is not normally a problem unless your
1096callbacks are really really fast or your OS is really really slow (I am
1097not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
1098
1099Setting these is useful if you want to ensure some level of
1100interactiveness when perl is not fast enough to process all requests in
1101time.
1102
1103For interactive programs, values such as C<0.01> to C<0.1> should be fine.
1104
1105Example: Install an Event watcher that automatically calls
1106IO::AIO::poll_cb with low priority, to ensure that other parts of the
1107program get the CPU sometimes even under high AIO load.
1108
1109 # try not to spend much more than 0.1s in poll_cb
1110 IO::AIO::max_poll_time 0.1;
1111
1112 # use a low priority so other tasks have priority
1113 Event->io (fd => IO::AIO::poll_fileno,
1114 poll => 'r', nice => 1,
1115 cb => &IO::AIO::poll_cb);
1116
815=item IO::AIO::poll_wait 1117=item IO::AIO::poll_wait
816 1118
1119If there are any outstanding requests and none of them in the result
817Wait till the result filehandle becomes ready for reading (simply does a 1120phase, wait till the result filehandle becomes ready for reading (simply
818C<select> on the filehandle. This is useful if you want to synchronously wait 1121does a C<select> on the filehandle. This is useful if you want to
819for some requests to finish). 1122synchronously wait for some requests to finish).
820 1123
821See C<nreqs> for an example. 1124See C<nreqs> for an example.
822 1125
1126=item IO::AIO::poll
1127
1128Waits until some requests have been handled.
1129
1130Returns the number of requests processed, but is otherwise strictly
1131equivalent to:
1132
1133 IO::AIO::poll_wait, IO::AIO::poll_cb
1134
823=item IO::AIO::nreqs 1135=item IO::AIO::flush
824 1136
825Returns the number of requests currently outstanding (i.e. for which their 1137Wait till all outstanding AIO requests have been handled.
826callback has not been invoked yet).
827 1138
828Example: wait till there are no outstanding requests anymore: 1139Strictly equivalent to:
829 1140
830 IO::AIO::poll_wait, IO::AIO::poll_cb 1141 IO::AIO::poll_wait, IO::AIO::poll_cb
831 while IO::AIO::nreqs; 1142 while IO::AIO::nreqs;
832 1143
833=item IO::AIO::flush 1144=back
834 1145
835Wait till all outstanding AIO requests have been handled. 1146=head3 CONTROLLING THE NUMBER OF THREADS
836 1147
837Strictly equivalent to: 1148=over
838
839 IO::AIO::poll_wait, IO::AIO::poll_cb
840 while IO::AIO::nreqs;
841
842=item IO::AIO::poll
843
844Waits until some requests have been handled.
845
846Strictly equivalent to:
847
848 IO::AIO::poll_wait, IO::AIO::poll_cb
849 if IO::AIO::nreqs;
850 1149
851=item IO::AIO::min_parallel $nthreads 1150=item IO::AIO::min_parallel $nthreads
852 1151
853Set the minimum number of AIO threads to C<$nthreads>. The current 1152Set the minimum number of AIO threads to C<$nthreads>. The current
854default is C<8>, which means eight asynchronous operations can execute 1153default is C<8>, which means eight asynchronous operations can execute
855concurrently at any one time (the number of outstanding requests, 1154concurrently at any one time (the number of outstanding requests,
856however, is unlimited). 1155however, is unlimited).
857 1156
858IO::AIO starts threads only on demand, when an AIO request is queued and 1157IO::AIO starts threads only on demand, when an AIO request is queued and
859no free thread exists. 1158no free thread exists. Please note that queueing up a hundred requests can
1159create demand for a hundred threads, even if it turns out that everything
1160is in the cache and could have been processed faster by a single thread.
860 1161
861It is recommended to keep the number of threads relatively low, as some 1162It is recommended to keep the number of threads relatively low, as some
862Linux kernel versions will scale negatively with the number of threads 1163Linux kernel versions will scale negatively with the number of threads
863(higher parallelity => MUCH higher latency). With current Linux 2.6 1164(higher parallelity => MUCH higher latency). With current Linux 2.6
864versions, 4-32 threads should be fine. 1165versions, 4-32 threads should be fine.
… …
878This module automatically runs C<max_parallel 0> at program end, to ensure 1179This module automatically runs C<max_parallel 0> at program end, to ensure
879that all threads are killed and that there are no outstanding requests. 1180that all threads are killed and that there are no outstanding requests.
880 1181
881Under normal circumstances you don't need to call this function. 1182Under normal circumstances you don't need to call this function.
882 1183
1184=item IO::AIO::max_idle $nthreads
1185
1186Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1187threads that did not get a request to process within 10 seconds). That
1188means if a thread becomes idle while C<$nthreads> other threads are also
1189idle, it will free its resources and exit.
1190
1191This is useful when you allow a large number of threads (e.g. 100 or 1000)
1192to allow for extremely high load situations, but want to free resources
1193under normal circumstances (1000 threads can easily consume 30MB of RAM).
1194
1195The default is probably ok in most situations, especially if thread
1196creation is fast. If thread creation is very slow on your system you might
1197want to use larger values.
1198
883=item $oldnreqs = IO::AIO::max_outstanding $nreqs 1199=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
884 1200
885[DEPRECATED] 1201This is a very bad function to use in interactive programs because it
1202blocks, and a bad way to reduce concurrency because it is inexact: Better
1203use an C<aio_group> together with a feed callback.
886 1204
887Sets the maximum number of outstanding requests to C<$nreqs>. If you 1205Sets the maximum number of outstanding requests to C<$nreqs>. If you
888try to queue up more than this number of requests, the caller will block until 1206to queue up more than this number of requests, the next call to the
889some requests have been handled. 1207C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1208function will block until the limit is no longer exceeded.
890 1209
891The default is very large, so normally there is no practical limit. If you 1210The default value is very large, so there is no practical limit on the
892queue up many requests in a loop it often improves speed if you set 1211number of outstanding requests.
893this to a relatively low number, such as C<100>.
894 1212
895This function does not work well together with C<aio_group>'s, and their 1213You can still queue as many requests as you want. Therefore,
896feeder interface is better suited to limiting concurrency, so do not use 1214C<max_oustsanding> is mainly useful in simple scripts (with low values) or
897this function. 1215as a stop gap to shield against fatal memory overflow (with large values).
898 1216
899Under normal circumstances you don't need to call this function. 1217=back
1218
1219=head3 STATISTICAL INFORMATION
1220
1221=over
1222
1223=item IO::AIO::nreqs
1224
1225Returns the number of requests currently in the ready, execute or pending
1226states (i.e. for which their callback has not been invoked yet).
1227
1228Example: wait till there are no outstanding requests anymore:
1229
1230 IO::AIO::poll_wait, IO::AIO::poll_cb
1231 while IO::AIO::nreqs;
1232
1233=item IO::AIO::nready
1234
1235Returns the number of requests currently in the ready state (not yet
1236executed).
1237
1238=item IO::AIO::npending
1239
1240Returns the number of requests currently in the pending state (executed,
1241but not yet processed by poll_cb).
900 1242
901=back 1243=back
902 1244
903=cut 1245=cut
904 1246
… …
918 *$sym 1260 *$sym
919} 1261}
920 1262
921min_parallel 8; 1263min_parallel 8;
922 1264
923END { 1265END { flush }
924 max_parallel 0;
925}
926 1266
9271; 12671;
928 1268
929=head2 FORK BEHAVIOUR 1269=head2 FORK BEHAVIOUR
930 1270
… …
936request/result processing, while the child frees the request/result queue 1276request/result processing, while the child frees the request/result queue
937(so that the requests started before the fork will only be handled in the 1277(so that the requests started before the fork will only be handled in the
938parent). Threads will be started on demand until the limit set in the 1278parent). Threads will be started on demand until the limit set in the
939parent process has been reached again. 1279parent process has been reached again.
940 1280
941Temporary memory that was allocated for request processing is not
942reclaimed in the child, however. While this is possible in some cases, it
943is almost impossible in others (threads are evil you know), so you will
944have to live with it. This is around 64k buffer (for sendfile, readahead
945emulation) + the size of the directory being scanned (readdir).
946
947In short: the parent will, after a short pause, continue as if fork had 1281In short: the parent will, after a short pause, continue as if fork had
948not been called, while the child will act as if IO::AIO has not been used 1282not been called, while the child will act as if IO::AIO has not been used
949yet. 1283yet.
950 1284
951=head2 MEMORY USAGE 1285=head2 MEMORY USAGE
… …
967temporary buffers, and each thread requires a stack and other data 1301temporary buffers, and each thread requires a stack and other data
968structures (usually around 16k-128k, depending on the OS). 1302structures (usually around 16k-128k, depending on the OS).
969 1303
970=head1 KNOWN BUGS 1304=head1 KNOWN BUGS
971 1305
972See FORK BEHAVIOUR, above. 1306Known bugs will be fixed in the next release.
973 1307
974=head1 SEE ALSO 1308=head1 SEE ALSO
975 1309
976L<Coro::AIO>. 1310L<Coro::AIO>.
977 1311

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