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Revision 1.96 by root, Fri Dec 22 04:05:50 2006 UTC vs.
Revision 1.220 by root, Sun Apr 1 17:46:02 2012 UTC

4 4
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", IO::AIO::O_RDONLY, 0, sub {
10 my $fh = shift 10 my $fh = shift
11 or die "/etc/passwd: $!"; 11 or die "/etc/passwd: $!";
12 ... 12 ...
13 }; 13 };
14 14
26 $req->cancel; # cancel request if still in queue 26 $req->cancel; # cancel request if still in queue
27 27
28 my $grp = aio_group sub { print "all stats done\n" }; 28 my $grp = aio_group sub { print "all stats done\n" };
29 add $grp aio_stat "..." for ...; 29 add $grp aio_stat "..." for ...;
30 30
31 # AnyEvent integration
32 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
33 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
34
35 # Event integration
36 Event->io (fd => IO::AIO::poll_fileno,
37 poll => 'r',
38 cb => \&IO::AIO::poll_cb);
39
40 # Glib/Gtk2 integration
41 add_watch Glib::IO IO::AIO::poll_fileno,
42 in => sub { IO::AIO::poll_cb; 1 };
43
44 # Tk integration
45 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46 readable => \&IO::AIO::poll_cb);
47
48 # Danga::Socket integration
49 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50 \&IO::AIO::poll_cb);
51
52=head1 DESCRIPTION 31=head1 DESCRIPTION
53 32
54This module implements asynchronous I/O using whatever means your 33This module implements asynchronous I/O using whatever means your
55operating system supports. 34operating system supports. It is implemented as an interface to C<libeio>
35(L<http://software.schmorp.de/pkg/libeio.html>).
56 36
57Asynchronous means that operations that can normally block your program 37Asynchronous means that operations that can normally block your program
58(e.g. reading from disk) will be done asynchronously: the operation 38(e.g. reading from disk) will be done asynchronously: the operation
59will still block, but you can do something else in the meantime. This 39will still block, but you can do something else in the meantime. This
60is extremely useful for programs that need to stay interactive even 40is extremely useful for programs that need to stay interactive even
62etc.), but can also be used to easily do operations in parallel that are 42etc.), 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 43normally 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 44on a RAID volume or over NFS when you do a number of stat operations
65concurrently. 45concurrently.
66 46
67While most of this works on all types of file descriptors (for example 47While most of this works on all types of file descriptors (for
68sockets), using these functions on file descriptors that support 48example sockets), using these functions on file descriptors that
69nonblocking operation (again, sockets, pipes etc.) is very inefficient or 49support nonblocking operation (again, sockets, pipes etc.) is
70might not work (aio_read fails on sockets/pipes/fifos). Use an event loop 50very inefficient. Use an event loop for that (such as the L<EV>
71for that (such as the L<Event|Event> module): IO::AIO will naturally fit 51module): IO::AIO will naturally fit into such an event loop itself.
72into such an event loop itself.
73 52
74In this version, a number of threads are started that execute your 53In this version, a number of threads are started that execute your
75requests and signal their completion. You don't need thread support 54requests and signal their completion. You don't need thread support
76in perl, and the threads created by this module will not be visible 55in perl, and the threads created by this module will not be visible
77to perl. In the future, this module might make use of the native aio 56to perl. In the future, this module might make use of the native aio
79not well-supported or restricted (GNU/Linux doesn't allow them on normal 58not well-supported or restricted (GNU/Linux doesn't allow them on normal
80files currently, for example), and they would only support aio_read and 59files currently, for example), and they would only support aio_read and
81aio_write, so the remaining functionality would have to be implemented 60aio_write, so the remaining functionality would have to be implemented
82using threads anyway. 61using threads anyway.
83 62
84Although the module will work with in the presence of other (Perl-) 63Although the module will work in the presence of other (Perl-) threads,
85threads, it is currently not reentrant in any way, so use appropriate 64it is currently not reentrant in any way, so use appropriate locking
86locking yourself, always call C<poll_cb> from within the same thread, or 65yourself, always call C<poll_cb> from within the same thread, or never
87never call C<poll_cb> (or other C<aio_> functions) recursively. 66call C<poll_cb> (or other C<aio_> functions) recursively.
88 67
89=head2 EXAMPLE 68=head2 EXAMPLE
90 69
91This is a simple example that uses the Event module and loads 70This is a simple example that uses the EV module and loads
92F</etc/passwd> asynchronously: 71F</etc/passwd> asynchronously:
93 72
94 use Fcntl; 73 use Fcntl;
95 use Event; 74 use EV;
96 use IO::AIO; 75 use IO::AIO;
97 76
98 # register the IO::AIO callback with Event 77 # register the IO::AIO callback with EV
99 Event->io (fd => IO::AIO::poll_fileno, 78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
100 poll => 'r',
101 cb => \&IO::AIO::poll_cb);
102 79
103 # queue the request to open /etc/passwd 80 # queue the request to open /etc/passwd
104 aio_open "/etc/passwd", O_RDONLY, 0, sub { 81 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
105 my $fh = shift 82 my $fh = shift
106 or die "error while opening: $!"; 83 or die "error while opening: $!";
107 84
108 # stat'ing filehandles is generally non-blocking 85 # stat'ing filehandles is generally non-blocking
109 my $size = -s $fh; 86 my $size = -s $fh;
118 95
119 # file contents now in $contents 96 # file contents now in $contents
120 print $contents; 97 print $contents;
121 98
122 # exit event loop and program 99 # exit event loop and program
123 Event::unloop; 100 EV::unloop;
124 }; 101 };
125 }; 102 };
126 103
127 # possibly queue up other requests, or open GUI windows, 104 # possibly queue up other requests, or open GUI windows,
128 # check for sockets etc. etc. 105 # check for sockets etc. etc.
129 106
130 # process events as long as there are some: 107 # process events as long as there are some:
131 Event::loop; 108 EV::loop;
132 109
133=head1 REQUEST ANATOMY AND LIFETIME 110=head1 REQUEST ANATOMY AND LIFETIME
134 111
135Every C<aio_*> function creates a request. which is a C data structure not 112Every C<aio_*> function creates a request. which is a C data structure not
136directly visible to Perl. 113directly visible to Perl.
184 161
185=cut 162=cut
186 163
187package IO::AIO; 164package IO::AIO;
188 165
189no warnings; 166use Carp ();
190use strict 'vars'; 167
168use common::sense;
191 169
192use base 'Exporter'; 170use base 'Exporter';
193 171
194BEGIN { 172BEGIN {
195 our $VERSION = '2.21'; 173 our $VERSION = '4.13';
196 174
197 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 175 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
198 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 176 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
199 aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link 177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
200 aio_move aio_copy aio_group aio_nop aio_mknod); 178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
179 aio_pathsync aio_readahead
180 aio_rename aio_link aio_move aio_copy aio_group
181 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs
185 aio_wd);
186
201 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
202 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
203 min_parallel max_parallel max_idle 189 min_parallel max_parallel max_idle idle_timeout
204 nreqs nready npending nthreads 190 nreqs nready npending nthreads
205 max_poll_time max_poll_reqs); 191 max_poll_time max_poll_reqs
192 sendfile fadvise madvise
193 mmap munmap munlock munlockall);
194
195 push @AIO_REQ, qw(aio_busy); # not exported
206 196
207 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 197 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
208 198
209 require XSLoader; 199 require XSLoader;
210 XSLoader::load ("IO::AIO", $VERSION); 200 XSLoader::load ("IO::AIO", $VERSION);
211} 201}
212 202
213=head1 FUNCTIONS 203=head1 FUNCTIONS
214 204
215=head2 AIO REQUEST FUNCTIONS 205=head2 QUICK OVERVIEW
206
207This section simply lists the prototypes of the most important functions
208for quick reference. See the following sections for function-by-function
209documentation.
210
211 aio_wd $pathname, $callback->($wd)
212 aio_open $pathname, $flags, $mode, $callback->($fh)
213 aio_close $fh, $callback->($status)
214 aio_seek $fh,$offset,$whence, $callback->($offs)
215 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
217 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
218 aio_readahead $fh,$offset,$length, $callback->($retval)
219 aio_stat $fh_or_path, $callback->($status)
220 aio_lstat $fh, $callback->($status)
221 aio_statvfs $fh_or_path, $callback->($statvfs)
222 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
223 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status)
225 aio_truncate $fh_or_path, $offset, $callback->($status)
226 aio_unlink $pathname, $callback->($status)
227 aio_mknod $pathname, $mode, $dev, $callback->($status)
228 aio_link $srcpath, $dstpath, $callback->($status)
229 aio_symlink $srcpath, $dstpath, $callback->($status)
230 aio_readlink $pathname, $callback->($link)
231 aio_realpath $pathname, $callback->($link)
232 aio_rename $srcpath, $dstpath, $callback->($status)
233 aio_mkdir $pathname, $mode, $callback->($status)
234 aio_rmdir $pathname, $callback->($status)
235 aio_readdir $pathname, $callback->($entries)
236 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
237 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
238 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
239 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
240 aio_load $pathname, $data, $callback->($status)
241 aio_copy $srcpath, $dstpath, $callback->($status)
242 aio_move $srcpath, $dstpath, $callback->($status)
243 aio_rmtree $pathname, $callback->($status)
244 aio_sync $callback->($status)
245 aio_syncfs $fh, $callback->($status)
246 aio_fsync $fh, $callback->($status)
247 aio_fdatasync $fh, $callback->($status)
248 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
249 aio_pathsync $pathname, $callback->($status)
250 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
252 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
253 aio_mlockall $flags, $callback->($status)
254 aio_group $callback->(...)
255 aio_nop $callback->()
256
257 $prev_pri = aioreq_pri [$pri]
258 aioreq_nice $pri_adjust
259
260 IO::AIO::poll_wait
261 IO::AIO::poll_cb
262 IO::AIO::poll
263 IO::AIO::flush
264 IO::AIO::max_poll_reqs $nreqs
265 IO::AIO::max_poll_time $seconds
266 IO::AIO::min_parallel $nthreads
267 IO::AIO::max_parallel $nthreads
268 IO::AIO::max_idle $nthreads
269 IO::AIO::idle_timeout $seconds
270 IO::AIO::max_outstanding $maxreqs
271 IO::AIO::nreqs
272 IO::AIO::nready
273 IO::AIO::npending
274
275 IO::AIO::sendfile $ofh, $ifh, $offset, $count
276 IO::AIO::fadvise $fh, $offset, $len, $advice
277 IO::AIO::madvise $scalar, $offset, $length, $advice
278 IO::AIO::mprotect $scalar, $offset, $length, $protect
279 IO::AIO::munlock $scalar, $offset = 0, $length = undef
280 IO::AIO::munlockall
281
282=head2 API NOTES
216 283
217All the C<aio_*> calls are more or less thin wrappers around the syscall 284All the C<aio_*> calls are more or less thin wrappers around the syscall
218with the same name (sans C<aio_>). The arguments are similar or identical, 285with the same name (sans C<aio_>). The arguments are similar or identical,
219and they all accept an additional (and optional) C<$callback> argument 286and they all accept an additional (and optional) C<$callback> argument
220which must be a code reference. This code reference will get called with 287which must be a code reference. This code reference will be called after
221the syscall return code (e.g. most syscalls return C<-1> on error, unlike 288the syscall has been executed in an asynchronous fashion. The results
222perl, which usually delivers "false") as it's sole argument when the given 289of the request will be passed as arguments to the callback (and, if an
223syscall has been executed asynchronously. 290error occured, in C<$!>) - for most requests the syscall return code (e.g.
291most syscalls return C<-1> on error, unlike perl, which usually delivers
292"false").
293
294Some requests (such as C<aio_readdir>) pass the actual results and
295communicate failures by passing C<undef>.
224 296
225All functions expecting a filehandle keep a copy of the filehandle 297All functions expecting a filehandle keep a copy of the filehandle
226internally until the request has finished. 298internally until the request has finished.
227 299
228All functions return request objects of type L<IO::AIO::REQ> that allow 300All functions return request objects of type L<IO::AIO::REQ> that allow
229further manipulation of those requests while they are in-flight. 301further manipulation of those requests while they are in-flight.
230 302
231The pathnames you pass to these routines I<must> be absolute and 303The pathnames you pass to these routines I<should> be absolute. The
232encoded as octets. The reason for the former is that at the time the 304reason for this is that at the time the request is being executed, the
233request is being executed, the current working directory could have 305current working directory could have changed. Alternatively, you can
234changed. Alternatively, you can make sure that you never change the 306make sure that you never change the current working directory anywhere
235current working directory anywhere in the program and then use relative 307in the program and then use relative paths. You can also take advantage
236paths. 308of IO::AIOs working directory abstraction, that lets you specify paths
309relative to some previously-opened "working directory object" - see the
310description of the C<IO::AIO::WD> class later in this document.
237 311
238To encode pathnames as octets, either make sure you either: a) always pass 312To encode pathnames as octets, either make sure you either: a) always pass
239in filenames you got from outside (command line, readdir etc.) without 313in filenames you got from outside (command line, readdir etc.) without
240tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 314tinkering, b) are in your native filesystem encoding, c) use the Encode
241your pathnames to the locale (or other) encoding in effect in the user 315module and encode your pathnames to the locale (or other) encoding in
242environment, d) use Glib::filename_from_unicode on unicode filenames or e) 316effect in the user environment, d) use Glib::filename_from_unicode on
243use something else to ensure your scalar has the correct contents. 317unicode filenames or e) use something else to ensure your scalar has the
318correct contents.
244 319
245This works, btw. independent of the internal UTF-8 bit, which IO::AIO 320This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246handles correctly wether it is set or not. 321handles correctly whether it is set or not.
322
323=head2 AIO REQUEST FUNCTIONS
247 324
248=over 4 325=over 4
249 326
250=item $prev_pri = aioreq_pri [$pri] 327=item $prev_pri = aioreq_pri [$pri]
251 328
271 aio_read $_[0], ..., sub { 348 aio_read $_[0], ..., sub {
272 ... 349 ...
273 }; 350 };
274 }; 351 };
275 352
353
276=item aioreq_nice $pri_adjust 354=item aioreq_nice $pri_adjust
277 355
278Similar to C<aioreq_pri>, but subtracts the given value from the current 356Similar to C<aioreq_pri>, but subtracts the given value from the current
279priority, so the effect is cumulative. 357priority, so the effect is cumulative.
358
280 359
281=item aio_open $pathname, $flags, $mode, $callback->($fh) 360=item aio_open $pathname, $flags, $mode, $callback->($fh)
282 361
283Asynchronously open or create a file and call the callback with a newly 362Asynchronously open or create a file and call the callback with a newly
284created filehandle for the file. 363created filehandle for the file.
290list. They are the same as used by C<sysopen>. 369list. They are the same as used by C<sysopen>.
291 370
292Likewise, C<$mode> specifies the mode of the newly created file, if it 371Likewise, C<$mode> specifies the mode of the newly created file, if it
293didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, 372didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
294except that it is mandatory (i.e. use C<0> if you don't create new files, 373except that it is mandatory (i.e. use C<0> if you don't create new files,
295and C<0666> or C<0777> if you do). 374and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
375by the umask in effect then the request is being executed, so better never
376change the umask.
296 377
297Example: 378Example:
298 379
299 aio_open "/etc/passwd", O_RDONLY, 0, sub { 380 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
300 if ($_[0]) { 381 if ($_[0]) {
301 print "open successful, fh is $_[0]\n"; 382 print "open successful, fh is $_[0]\n";
302 ... 383 ...
303 } else { 384 } else {
304 die "open failed: $!\n"; 385 die "open failed: $!\n";
305 } 386 }
306 }; 387 };
307 388
389In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
390C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
391following POSIX and non-POSIX constants are available (missing ones on
392your system are, as usual, C<0>):
393
394C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
395C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
396C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
397
398
308=item aio_close $fh, $callback->($status) 399=item aio_close $fh, $callback->($status)
309 400
310Asynchronously close a file and call the callback with the result 401Asynchronously close a file and call the callback with the result
311code. I<WARNING:> although accepted, you should not pass in a perl 402code.
312filehandle here, as perl will likely close the file descriptor another
313time when the filehandle is destroyed. Normally, you can safely call perls
314C<close> or just let filehandles go out of scope.
315 403
316This is supposed to be a bug in the API, so that might change. It's 404Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
317therefore best to avoid this function. 405closing the file descriptor associated with the filehandle itself.
406
407Therefore, C<aio_close> will not close the filehandle - instead it will
408use dup2 to overwrite the file descriptor with the write-end of a pipe
409(the pipe fd will be created on demand and will be cached).
410
411Or in other words: the file descriptor will be closed, but it will not be
412free for reuse until the perl filehandle is closed.
413
414=cut
415
416=item aio_seek $fh, $offset, $whence, $callback->($offs)
417
418Seeks the filehandle to the new C<$offset>, similarly to perl'S
419C<sysseek>. The C<$whence> can use the traditional values (C<0> for
420C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
421C<IO::AIO::SEEK_END>).
422
423The resulting absolute offset will be passed to the callback, or C<-1> in
424case of an error.
425
426In theory, the C<$whence> constants could be different than the
427corresponding values from L<Fcntl>, but perl guarantees they are the same,
428so don't panic.
318 429
319=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 430=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
320 431
321=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 432=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322 433
323Reads or writes C<length> bytes from the specified C<fh> and C<offset> 434Reads or writes C<$length> bytes from or to the specified C<$fh> and
324into the scalar given by C<data> and offset C<dataoffset> and calls the 435C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
325callback without the actual number of bytes read (or -1 on error, just 436and calls the callback without the actual number of bytes read (or -1 on
326like the syscall). 437error, just like the syscall).
438
439C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
440offset plus the actual number of bytes read.
441
442If C<$offset> is undefined, then the current file descriptor offset will
443be used (and updated), otherwise the file descriptor offset will not be
444changed by these calls.
445
446If C<$length> is undefined in C<aio_write>, use the remaining length of
447C<$data>.
448
449If C<$dataoffset> is less than zero, it will be counted from the end of
450C<$data>.
327 451
328The C<$data> scalar I<MUST NOT> be modified in any way while the request 452The C<$data> scalar I<MUST NOT> be modified in any way while the request
329is outstanding. Modifying it can result in segfaults or WW3 (if the 453is outstanding. Modifying it can result in segfaults or World War III (if
330necessary/optional hardware is installed). 454the necessary/optional hardware is installed).
331 455
332Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at 456Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
333offset C<0> within the scalar: 457offset C<0> within the scalar:
334 458
335 aio_read $fh, 7, 15, $buffer, 0, sub { 459 aio_read $fh, 7, 15, $buffer, 0, sub {
336 $_[0] > 0 or die "read error: $!"; 460 $_[0] > 0 or die "read error: $!";
337 print "read $_[0] bytes: <$buffer>\n"; 461 print "read $_[0] bytes: <$buffer>\n";
338 }; 462 };
339 463
464
340=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 465=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
341 466
342Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 467Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
343reading at byte offset C<$in_offset>, and starts writing at the current 468reading at byte offset C<$in_offset>, and starts writing at the current
344file offset of C<$out_fh>. Because of that, it is not safe to issue more 469file offset of C<$out_fh>. Because of that, it is not safe to issue more
345than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 470than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
346other. 471other. The same C<$in_fh> works fine though, as this function does not
472move or use the file offset of C<$in_fh>.
347 473
474Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
475are written, and there is no way to find out how many more bytes have been
476read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
477number of bytes written to C<$out_fh>. Only if the result value equals
478C<$length> one can assume that C<$length> bytes have been read.
479
480Unlike with other C<aio_> functions, it makes a lot of sense to use
481C<aio_sendfile> on non-blocking sockets, as long as one end (typically
482the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
483the socket I/O will be non-blocking. Note, however, that you can run
484into a trap where C<aio_sendfile> reads some data with readahead, then
485fails to write all data, and when the socket is ready the next time, the
486data in the cache is already lost, forcing C<aio_sendfile> to again hit
487the disk. Explicit C<aio_read> + C<aio_write> let's you better control
488resource usage.
489
348This call tries to make use of a native C<sendfile> syscall to provide 490This call tries to make use of a native C<sendfile>-like syscall to
349zero-copy operation. For this to work, C<$out_fh> should refer to a 491provide zero-copy operation. For this to work, C<$out_fh> should refer to
350socket, and C<$in_fh> should refer to mmap'able file. 492a socket, and C<$in_fh> should refer to an mmap'able file.
351 493
352If the native sendfile call fails or is not implemented, it will be 494If a native sendfile cannot be found or it fails with C<ENOSYS>,
353emulated, so you can call C<aio_sendfile> on any type of filehandle 495C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
496C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
354regardless of the limitations of the operating system. 497type of filehandle regardless of the limitations of the operating system.
355 498
356Please note, however, that C<aio_sendfile> can read more bytes from 499As native sendfile syscalls (as practically any non-POSIX interface hacked
357C<$in_fh> than are written, and there is no way to find out how many 500together in a hurry to improve benchmark numbers) tend to be rather buggy
358bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 501on many systems, this implementation tries to work around some known bugs
359provides the number of bytes written to C<$out_fh>. Only if the result 502in Linux and FreeBSD kernels (probably others, too), but that might fail,
360value equals C<$length> one can assume that C<$length> bytes have been 503so you really really should check the return value of C<aio_sendfile> -
361read. 504fewre bytes than expected might have been transferred.
505
362 506
363=item aio_readahead $fh,$offset,$length, $callback->($retval) 507=item aio_readahead $fh,$offset,$length, $callback->($retval)
364 508
365C<aio_readahead> populates the page cache with data from a file so that 509C<aio_readahead> populates the page cache with data from a file so that
366subsequent reads from that file will not block on disk I/O. The C<$offset> 510subsequent reads from that file will not block on disk I/O. The C<$offset>
372file. The current file offset of the file is left unchanged. 516file. The current file offset of the file is left unchanged.
373 517
374If that syscall doesn't exist (likely if your OS isn't Linux) it will be 518If that syscall doesn't exist (likely if your OS isn't Linux) it will be
375emulated by simply reading the data, which would have a similar effect. 519emulated by simply reading the data, which would have a similar effect.
376 520
521
377=item aio_stat $fh_or_path, $callback->($status) 522=item aio_stat $fh_or_path, $callback->($status)
378 523
379=item aio_lstat $fh, $callback->($status) 524=item aio_lstat $fh, $callback->($status)
380 525
381Works like perl's C<stat> or C<lstat> in void context. The callback will 526Works like perl's C<stat> or C<lstat> in void context. The callback will
386for an explanation. 531for an explanation.
387 532
388Currently, the stats are always 64-bit-stats, i.e. instead of returning an 533Currently, the stats are always 64-bit-stats, i.e. instead of returning an
389error when stat'ing a large file, the results will be silently truncated 534error when stat'ing a large file, the results will be silently truncated
390unless perl itself is compiled with large file support. 535unless perl itself is compiled with large file support.
536
537To help interpret the mode and dev/rdev stat values, IO::AIO offers the
538following constants and functions (if not implemented, the constants will
539be C<0> and the functions will either C<croak> or fall back on traditional
540behaviour).
541
542C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
543C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
544C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
391 545
392Example: Print the length of F</etc/passwd>: 546Example: Print the length of F</etc/passwd>:
393 547
394 aio_stat "/etc/passwd", sub { 548 aio_stat "/etc/passwd", sub {
395 $_[0] and die "stat failed: $!"; 549 $_[0] and die "stat failed: $!";
396 print "size is ", -s _, "\n"; 550 print "size is ", -s _, "\n";
397 }; 551 };
398 552
553
554=item aio_statvfs $fh_or_path, $callback->($statvfs)
555
556Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
557whether a file handle or path was passed.
558
559On success, the callback is passed a hash reference with the following
560members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
561C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
562is passed.
563
564The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
565C<ST_NOSUID>.
566
567The following non-POSIX IO::AIO::ST_* flag masks are defined to
568their correct value when available, or to C<0> on systems that do
569not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
570C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
571C<ST_NODIRATIME> and C<ST_RELATIME>.
572
573Example: stat C</wd> and dump out the data if successful.
574
575 aio_statvfs "/wd", sub {
576 my $f = $_[0]
577 or die "statvfs: $!";
578
579 use Data::Dumper;
580 say Dumper $f;
581 };
582
583 # result:
584 {
585 bsize => 1024,
586 bfree => 4333064312,
587 blocks => 10253828096,
588 files => 2050765568,
589 flag => 4096,
590 favail => 2042092649,
591 bavail => 4333064312,
592 ffree => 2042092649,
593 namemax => 255,
594 frsize => 1024,
595 fsid => 1810
596 }
597
598
599=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
600
601Works like perl's C<utime> function (including the special case of $atime
602and $mtime being undef). Fractional times are supported if the underlying
603syscalls support them.
604
605When called with a pathname, uses utimes(2) if available, otherwise
606utime(2). If called on a file descriptor, uses futimes(2) if available,
607otherwise returns ENOSYS, so this is not portable.
608
609Examples:
610
611 # set atime and mtime to current time (basically touch(1)):
612 aio_utime "path", undef, undef;
613 # set atime to current time and mtime to beginning of the epoch:
614 aio_utime "path", time, undef; # undef==0
615
616
617=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
618
619Works like perl's C<chown> function, except that C<undef> for either $uid
620or $gid is being interpreted as "do not change" (but -1 can also be used).
621
622Examples:
623
624 # same as "chown root path" in the shell:
625 aio_chown "path", 0, -1;
626 # same as above:
627 aio_chown "path", 0, undef;
628
629
630=item aio_truncate $fh_or_path, $offset, $callback->($status)
631
632Works like truncate(2) or ftruncate(2).
633
634
635=item aio_chmod $fh_or_path, $mode, $callback->($status)
636
637Works like perl's C<chmod> function.
638
639
399=item aio_unlink $pathname, $callback->($status) 640=item aio_unlink $pathname, $callback->($status)
400 641
401Asynchronously unlink (delete) a file and call the callback with the 642Asynchronously unlink (delete) a file and call the callback with the
402result code. 643result code.
403 644
645
404=item aio_mknod $path, $mode, $dev, $callback->($status) 646=item aio_mknod $pathname, $mode, $dev, $callback->($status)
405 647
406[EXPERIMENTAL] 648[EXPERIMENTAL]
407 649
408Asynchronously create a device node (or fifo). See mknod(2). 650Asynchronously create a device node (or fifo). See mknod(2).
409 651
410The only (POSIX-) portable way of calling this function is: 652The only (POSIX-) portable way of calling this function is:
411 653
412 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 654 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
655
656See C<aio_stat> for info about some potentially helpful extra constants
657and functions.
413 658
414=item aio_link $srcpath, $dstpath, $callback->($status) 659=item aio_link $srcpath, $dstpath, $callback->($status)
415 660
416Asynchronously create a new link to the existing object at C<$srcpath> at 661Asynchronously create a new link to the existing object at C<$srcpath> at
417the path C<$dstpath> and call the callback with the result code. 662the path C<$dstpath> and call the callback with the result code.
418 663
664
419=item aio_symlink $srcpath, $dstpath, $callback->($status) 665=item aio_symlink $srcpath, $dstpath, $callback->($status)
420 666
421Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 667Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
422the path C<$dstpath> and call the callback with the result code. 668the path C<$dstpath> and call the callback with the result code.
423 669
670
424=item aio_readlink $path, $callback->($link) 671=item aio_readlink $pathname, $callback->($link)
425 672
426Asynchronously read the symlink specified by C<$path> and pass it to 673Asynchronously read the symlink specified by C<$path> and pass it to
427the callback. If an error occurs, nothing or undef gets passed to the 674the callback. If an error occurs, nothing or undef gets passed to the
428callback. 675callback.
429 676
677
678=item aio_realpath $pathname, $callback->($path)
679
680Asynchronously make the path absolute and resolve any symlinks in
681C<$path>. The resulting path only consists of directories (Same as
682L<Cwd::realpath>).
683
684This request can be used to get the absolute path of the current working
685directory by passing it a path of F<.> (a single dot).
686
687
430=item aio_rename $srcpath, $dstpath, $callback->($status) 688=item aio_rename $srcpath, $dstpath, $callback->($status)
431 689
432Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 690Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
433rename(2) and call the callback with the result code. 691rename(2) and call the callback with the result code.
434 692
693
694=item aio_mkdir $pathname, $mode, $callback->($status)
695
696Asynchronously mkdir (create) a directory and call the callback with
697the result code. C<$mode> will be modified by the umask at the time the
698request is executed, so do not change your umask.
699
700
435=item aio_rmdir $pathname, $callback->($status) 701=item aio_rmdir $pathname, $callback->($status)
436 702
437Asynchronously rmdir (delete) a directory and call the callback with the 703Asynchronously rmdir (delete) a directory and call the callback with the
438result code. 704result code.
705
439 706
440=item aio_readdir $pathname, $callback->($entries) 707=item aio_readdir $pathname, $callback->($entries)
441 708
442Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 709Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
443directory (i.e. opendir + readdir + closedir). The entries will not be 710directory (i.e. opendir + readdir + closedir). The entries will not be
444sorted, and will B<NOT> include the C<.> and C<..> entries. 711sorted, and will B<NOT> include the C<.> and C<..> entries.
445 712
446The callback a single argument which is either C<undef> or an array-ref 713The callback is passed a single argument which is either C<undef> or an
447with the filenames. 714array-ref with the filenames.
715
716
717=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
718
719Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
720tune behaviour and output format. In case of an error, C<$entries> will be
721C<undef>.
722
723The flags are a combination of the following constants, ORed together (the
724flags will also be passed to the callback, possibly modified):
725
726=over 4
727
728=item IO::AIO::READDIR_DENTS
729
730When this flag is off, then the callback gets an arrayref consisting of
731names only (as with C<aio_readdir>), otherwise it gets an arrayref with
732C<[$name, $type, $inode]> arrayrefs, each describing a single directory
733entry in more detail.
734
735C<$name> is the name of the entry.
736
737C<$type> is one of the C<IO::AIO::DT_xxx> constants:
738
739C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
740C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
741C<IO::AIO::DT_WHT>.
742
743C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
744know, you have to run stat yourself. Also, for speed reasons, the C<$type>
745scalars are read-only: you can not modify them.
746
747C<$inode> is the inode number (which might not be exact on systems with 64
748bit inode numbers and 32 bit perls). This field has unspecified content on
749systems that do not deliver the inode information.
750
751=item IO::AIO::READDIR_DIRS_FIRST
752
753When this flag is set, then the names will be returned in an order where
754likely directories come first, in optimal stat order. This is useful when
755you need to quickly find directories, or you want to find all directories
756while avoiding to stat() each entry.
757
758If the system returns type information in readdir, then this is used
759to find directories directly. Otherwise, likely directories are names
760beginning with ".", or otherwise names with no dots, of which names with
761short names are tried first.
762
763=item IO::AIO::READDIR_STAT_ORDER
764
765When this flag is set, then the names will be returned in an order
766suitable for stat()'ing each one. That is, when you plan to stat()
767all files in the given directory, then the returned order will likely
768be fastest.
769
770If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
771the likely dirs come first, resulting in a less optimal stat order.
772
773=item IO::AIO::READDIR_FOUND_UNKNOWN
774
775This flag should not be set when calling C<aio_readdirx>. Instead, it
776is being set by C<aio_readdirx>, when any of the C<$type>'s found were
777C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
778C<$type>'s are known, which can be used to speed up some algorithms.
779
780=back
781
782
783=item aio_load $pathname, $data, $callback->($status)
784
785This is a composite request that tries to fully load the given file into
786memory. Status is the same as with aio_read.
787
788=cut
789
790sub aio_load($$;$) {
791 my ($path, undef, $cb) = @_;
792 my $data = \$_[1];
793
794 my $pri = aioreq_pri;
795 my $grp = aio_group $cb;
796
797 aioreq_pri $pri;
798 add $grp aio_open $path, O_RDONLY, 0, sub {
799 my $fh = shift
800 or return $grp->result (-1);
801
802 aioreq_pri $pri;
803 add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
804 $grp->result ($_[0]);
805 };
806 };
807
808 $grp
809}
448 810
449=item aio_copy $srcpath, $dstpath, $callback->($status) 811=item aio_copy $srcpath, $dstpath, $callback->($status)
450 812
451Try to copy the I<file> (directories not supported as either source or 813Try to copy the I<file> (directories not supported as either source or
452destination) from C<$srcpath> to C<$dstpath> and call the callback with 814destination) from C<$srcpath> to C<$dstpath> and call the callback with
453the C<0> (error) or C<-1> ok. 815a status of C<0> (ok) or C<-1> (error, see C<$!>).
454 816
455This is a composite request that it creates the destination file with 817This is a composite request that creates the destination file with
456mode 0200 and copies the contents of the source file into it using 818mode 0200 and copies the contents of the source file into it using
457C<aio_sendfile>, followed by restoring atime, mtime, access mode and 819C<aio_sendfile>, followed by restoring atime, mtime, access mode and
458uid/gid, in that order. 820uid/gid, in that order.
459 821
460If an error occurs, the partial destination file will be unlinked, if 822If an error occurs, the partial destination file will be unlinked, if
462errors are being ignored. 824errors are being ignored.
463 825
464=cut 826=cut
465 827
466sub aio_copy($$;$) { 828sub aio_copy($$;$) {
467 aio_block {
468 my ($src, $dst, $cb) = @_; 829 my ($src, $dst, $cb) = @_;
469 830
470 my $pri = aioreq_pri; 831 my $pri = aioreq_pri;
471 my $grp = aio_group $cb; 832 my $grp = aio_group $cb;
472 833
473 aioreq_pri $pri; 834 aioreq_pri $pri;
474 add $grp aio_open $src, O_RDONLY, 0, sub { 835 add $grp aio_open $src, O_RDONLY, 0, sub {
475 if (my $src_fh = $_[0]) { 836 if (my $src_fh = $_[0]) {
476 my @stat = stat $src_fh; 837 my @stat = stat $src_fh; # hmm, might block over nfs?
477 838
478 aioreq_pri $pri; 839 aioreq_pri $pri;
479 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { 840 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
480 if (my $dst_fh = $_[0]) { 841 if (my $dst_fh = $_[0]) {
481 aioreq_pri $pri; 842 aioreq_pri $pri;
482 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { 843 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
483 if ($_[0] == $stat[7]) { 844 if ($_[0] == $stat[7]) {
484 $grp->result (0); 845 $grp->result (0);
485 close $src_fh; 846 close $src_fh;
486 847
487 # those should not normally block. should. should.
488 utime $stat[8], $stat[9], $dst;
489 chmod $stat[2] & 07777, $dst_fh;
490 chown $stat[4], $stat[5], $dst_fh;
491 close $dst_fh;
492 } else { 848 my $ch = sub {
493 $grp->result (-1);
494 close $src_fh;
495 close $dst_fh;
496
497 aioreq $pri; 849 aioreq_pri $pri;
850 add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
851 aioreq_pri $pri;
852 add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
853 aioreq_pri $pri;
498 add $grp aio_unlink $dst; 854 add $grp aio_close $dst_fh;
855 }
856 };
499 } 857 };
858
859 aioreq_pri $pri;
860 add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
861 if ($_[0] < 0 && $! == ENOSYS) {
862 aioreq_pri $pri;
863 add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
864 } else {
865 $ch->();
866 }
867 };
868 } else {
869 $grp->result (-1);
870 close $src_fh;
871 close $dst_fh;
872
873 aioreq $pri;
874 add $grp aio_unlink $dst;
500 }; 875 }
501 } else {
502 $grp->result (-1);
503 } 876 };
877 } else {
878 $grp->result (-1);
504 }, 879 }
505
506 } else {
507 $grp->result (-1);
508 } 880 },
881
882 } else {
883 $grp->result (-1);
509 }; 884 }
510
511 $grp
512 } 885 };
886
887 $grp
513} 888}
514 889
515=item aio_move $srcpath, $dstpath, $callback->($status) 890=item aio_move $srcpath, $dstpath, $callback->($status)
516 891
517Try to move the I<file> (directories not supported as either source or 892Try to move the I<file> (directories not supported as either source or
518destination) from C<$srcpath> to C<$dstpath> and call the callback with 893destination) from C<$srcpath> to C<$dstpath> and call the callback with
519the C<0> (error) or C<-1> ok. 894a status of C<0> (ok) or C<-1> (error, see C<$!>).
520 895
521This is a composite request that tries to rename(2) the file first. If 896This is a composite request that tries to rename(2) the file first; if
522rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if 897rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
523that is successful, unlinking the C<$srcpath>. 898that is successful, unlinks the C<$srcpath>.
524 899
525=cut 900=cut
526 901
527sub aio_move($$;$) { 902sub aio_move($$;$) {
528 aio_block {
529 my ($src, $dst, $cb) = @_; 903 my ($src, $dst, $cb) = @_;
530 904
531 my $pri = aioreq_pri; 905 my $pri = aioreq_pri;
532 my $grp = aio_group $cb; 906 my $grp = aio_group $cb;
533 907
534 aioreq_pri $pri; 908 aioreq_pri $pri;
535 add $grp aio_rename $src, $dst, sub { 909 add $grp aio_rename $src, $dst, sub {
536 if ($_[0] && $! == EXDEV) { 910 if ($_[0] && $! == EXDEV) {
537 aioreq_pri $pri; 911 aioreq_pri $pri;
538 add $grp aio_copy $src, $dst, sub { 912 add $grp aio_copy $src, $dst, sub {
539 $grp->result ($_[0]);
540
541 if (!$_[0]) {
542 aioreq_pri $pri;
543 add $grp aio_unlink $src;
544 }
545 };
546 } else {
547 $grp->result ($_[0]); 913 $grp->result ($_[0]);
914
915 unless ($_[0]) {
916 aioreq_pri $pri;
917 add $grp aio_unlink $src;
918 }
548 } 919 };
920 } else {
921 $grp->result ($_[0]);
549 }; 922 }
550
551 $grp
552 } 923 };
924
925 $grp
553} 926}
554 927
555=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 928=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
556 929
557Scans a directory (similar to C<aio_readdir>) but additionally tries to 930Scans a directory (similar to C<aio_readdir>) but additionally tries to
558efficiently separate the entries of directory C<$path> into two sets of 931efficiently separate the entries of directory C<$path> into two sets of
559names, directories you can recurse into (directories), and ones you cannot 932names, directories you can recurse into (directories), and ones you cannot
560recurse into (everything else, including symlinks to directories). 933recurse into (everything else, including symlinks to directories).
577 950
578Implementation notes. 951Implementation notes.
579 952
580The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. 953The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
581 954
955If readdir returns file type information, then this is used directly to
956find directories.
957
582After reading the directory, the modification time, size etc. of the 958Otherwise, after reading the directory, the modification time, size etc.
583directory before and after the readdir is checked, and if they match (and 959of the directory before and after the readdir is checked, and if they
584isn't the current time), the link count will be used to decide how many 960match (and isn't the current time), the link count will be used to decide
585entries are directories (if >= 2). Otherwise, no knowledge of the number 961how many entries are directories (if >= 2). Otherwise, no knowledge of the
586of subdirectories will be assumed. 962number of subdirectories will be assumed.
587 963
588Then entries will be sorted into likely directories (everything without 964Then entries will be sorted into likely directories a non-initial dot
589a non-initial dot currently) and likely non-directories (everything 965currently) and likely non-directories (see C<aio_readdirx>). Then every
590else). Then every entry plus an appended C</.> will be C<stat>'ed, 966entry plus an appended C</.> will be C<stat>'ed, likely directories first,
591likely directories first. If that succeeds, it assumes that the entry 967in order of their inode numbers. If that succeeds, it assumes that the
592is a directory or a symlink to directory (which will be checked 968entry is a directory or a symlink to directory (which will be checked
593seperately). This is often faster than stat'ing the entry itself because 969separately). This is often faster than stat'ing the entry itself because
594filesystems might detect the type of the entry without reading the inode 970filesystems might detect the type of the entry without reading the inode
595data (e.g. ext2fs filetype feature). 971data (e.g. ext2fs filetype feature), even on systems that cannot return
972the filetype information on readdir.
596 973
597If the known number of directories (link count - 2) has been reached, the 974If the known number of directories (link count - 2) has been reached, the
598rest of the entries is assumed to be non-directories. 975rest of the entries is assumed to be non-directories.
599 976
600This only works with certainty on POSIX (= UNIX) filesystems, which 977This only works with certainty on POSIX (= UNIX) filesystems, which
604as those tend to return 0 or 1 as link counts, which disables the 981as those tend to return 0 or 1 as link counts, which disables the
605directory counting heuristic. 982directory counting heuristic.
606 983
607=cut 984=cut
608 985
609sub aio_scandir($$$) { 986sub aio_scandir($$;$) {
610 aio_block {
611 my ($path, $maxreq, $cb) = @_; 987 my ($path, $maxreq, $cb) = @_;
612 988
613 my $pri = aioreq_pri; 989 my $pri = aioreq_pri;
614 990
615 my $grp = aio_group $cb; 991 my $grp = aio_group $cb;
616 992
617 $maxreq = 4 if $maxreq <= 0; 993 $maxreq = 4 if $maxreq <= 0;
994
995 # get a wd object
996 aioreq_pri $pri;
997 add $grp aio_wd $path, sub {
998 $_[0]
999 or return $grp->result ();
1000
1001 my $wd = [shift, "."];
618 1002
619 # stat once 1003 # stat once
620 aioreq_pri $pri; 1004 aioreq_pri $pri;
621 add $grp aio_stat $path, sub { 1005 add $grp aio_stat $wd, sub {
622 return $grp->result () if $_[0]; 1006 return $grp->result () if $_[0];
623 my $now = time; 1007 my $now = time;
624 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 1008 my $hash1 = join ":", (stat _)[0,1,3,7,9];
625 1009
626 # read the directory entries 1010 # read the directory entries
627 aioreq_pri $pri; 1011 aioreq_pri $pri;
628 add $grp aio_readdir $path, sub { 1012 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
629 my $entries = shift 1013 my $entries = shift
630 or return $grp->result (); 1014 or return $grp->result ();
631 1015
632 # stat the dir another time 1016 # stat the dir another time
633 aioreq_pri $pri; 1017 aioreq_pri $pri;
634 add $grp aio_stat $path, sub { 1018 add $grp aio_stat $wd, sub {
635 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1019 my $hash2 = join ":", (stat _)[0,1,3,7,9];
636 1020
637 my $ndirs; 1021 my $ndirs;
638 1022
639 # take the slow route if anything looks fishy 1023 # take the slow route if anything looks fishy
640 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1024 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
641 $ndirs = -1; 1025 $ndirs = -1;
642 } else { 1026 } else {
643 # if nlink == 2, we are finished 1027 # if nlink == 2, we are finished
644 # on non-posix-fs's, we rely on nlink < 2 1028 # for non-posix-fs's, we rely on nlink < 2
645 $ndirs = (stat _)[3] - 2 1029 $ndirs = (stat _)[3] - 2
646 or return $grp->result ([], $entries); 1030 or return $grp->result ([], $entries);
647 } 1031 }
648 1032
649 # sort into likely dirs and likely nondirs
650 # dirs == files without ".", short entries first
651 $entries = [map $_->[0],
652 sort { $b->[1] cmp $a->[1] }
653 map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
654 @$entries];
655
656 my (@dirs, @nondirs); 1033 my (@dirs, @nondirs);
657 1034
658 my $statgrp = add $grp aio_group sub { 1035 my $statgrp = add $grp aio_group sub {
659 $grp->result (\@dirs, \@nondirs); 1036 $grp->result (\@dirs, \@nondirs);
660 }; 1037 };
661 1038
662 limit $statgrp $maxreq; 1039 limit $statgrp $maxreq;
663 feed $statgrp sub { 1040 feed $statgrp sub {
664 return unless @$entries; 1041 return unless @$entries;
665 my $entry = pop @$entries; 1042 my $entry = shift @$entries;
666 1043
667 aioreq_pri $pri; 1044 aioreq_pri $pri;
1045 $wd->[1] = "$entry/.";
668 add $statgrp aio_stat "$path/$entry/.", sub { 1046 add $statgrp aio_stat $wd, sub {
669 if ($_[0] < 0) { 1047 if ($_[0] < 0) {
670 push @nondirs, $entry; 1048 push @nondirs, $entry;
671 } else { 1049 } else {
672 # need to check for real directory 1050 # need to check for real directory
673 aioreq_pri $pri; 1051 aioreq_pri $pri;
1052 $wd->[1] = $entry;
674 add $statgrp aio_lstat "$path/$entry", sub { 1053 add $statgrp aio_lstat $wd, sub {
675 if (-d _) { 1054 if (-d _) {
676 push @dirs, $entry; 1055 push @dirs, $entry;
677 1056
678 unless (--$ndirs) { 1057 unless (--$ndirs) {
679 push @nondirs, @$entries; 1058 push @nondirs, @$entries;
687 }; 1066 };
688 }; 1067 };
689 }; 1068 };
690 }; 1069 };
691 }; 1070 };
692
693 $grp
694 } 1071 };
1072
1073 $grp
695} 1074}
1075
1076=item aio_rmtree $pathname, $callback->($status)
1077
1078Delete a directory tree starting (and including) C<$path>, return the
1079status of the final C<rmdir> only. This is a composite request that
1080uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1081everything else.
1082
1083=cut
1084
1085sub aio_rmtree;
1086sub aio_rmtree($;$) {
1087 my ($path, $cb) = @_;
1088
1089 my $pri = aioreq_pri;
1090 my $grp = aio_group $cb;
1091
1092 aioreq_pri $pri;
1093 add $grp aio_scandir $path, 0, sub {
1094 my ($dirs, $nondirs) = @_;
1095
1096 my $dirgrp = aio_group sub {
1097 add $grp aio_rmdir $path, sub {
1098 $grp->result ($_[0]);
1099 };
1100 };
1101
1102 (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
1103 (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
1104
1105 add $grp $dirgrp;
1106 };
1107
1108 $grp
1109}
1110
1111=item aio_sync $callback->($status)
1112
1113Asynchronously call sync and call the callback when finished.
696 1114
697=item aio_fsync $fh, $callback->($status) 1115=item aio_fsync $fh, $callback->($status)
698 1116
699Asynchronously call fsync on the given filehandle and call the callback 1117Asynchronously call fsync on the given filehandle and call the callback
700with the fsync result code. 1118with the fsync result code.
704Asynchronously call fdatasync on the given filehandle and call the 1122Asynchronously call fdatasync on the given filehandle and call the
705callback with the fdatasync result code. 1123callback with the fdatasync result code.
706 1124
707If this call isn't available because your OS lacks it or it couldn't be 1125If this call isn't available because your OS lacks it or it couldn't be
708detected, it will be emulated by calling C<fsync> instead. 1126detected, it will be emulated by calling C<fsync> instead.
1127
1128=item aio_syncfs $fh, $callback->($status)
1129
1130Asynchronously call the syncfs syscall to sync the filesystem associated
1131to the given filehandle and call the callback with the syncfs result
1132code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1133errno to C<ENOSYS> nevertheless.
1134
1135=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1136
1137Sync the data portion of the file specified by C<$offset> and C<$length>
1138to disk (but NOT the metadata), by calling the Linux-specific
1139sync_file_range call. If sync_file_range is not available or it returns
1140ENOSYS, then fdatasync or fsync is being substituted.
1141
1142C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1143C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1144C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1145manpage for details.
1146
1147=item aio_pathsync $pathname, $callback->($status)
1148
1149This request tries to open, fsync and close the given path. This is a
1150composite request intended to sync directories after directory operations
1151(E.g. rename). This might not work on all operating systems or have any
1152specific effect, but usually it makes sure that directory changes get
1153written to disc. It works for anything that can be opened for read-only,
1154not just directories.
1155
1156Future versions of this function might fall back to other methods when
1157C<fsync> on the directory fails (such as calling C<sync>).
1158
1159Passes C<0> when everything went ok, and C<-1> on error.
1160
1161=cut
1162
1163sub aio_pathsync($;$) {
1164 my ($path, $cb) = @_;
1165
1166 my $pri = aioreq_pri;
1167 my $grp = aio_group $cb;
1168
1169 aioreq_pri $pri;
1170 add $grp aio_open $path, O_RDONLY, 0, sub {
1171 my ($fh) = @_;
1172 if ($fh) {
1173 aioreq_pri $pri;
1174 add $grp aio_fsync $fh, sub {
1175 $grp->result ($_[0]);
1176
1177 aioreq_pri $pri;
1178 add $grp aio_close $fh;
1179 };
1180 } else {
1181 $grp->result (-1);
1182 }
1183 };
1184
1185 $grp
1186}
1187
1188=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1189
1190This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1191scalars (see the C<IO::AIO::mmap> function, although it also works on data
1192scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1193scalar must only be modified in-place while an aio operation is pending on
1194it).
1195
1196It calls the C<msync> function of your OS, if available, with the memory
1197area starting at C<$offset> in the string and ending C<$length> bytes
1198later. If C<$length> is negative, counts from the end, and if C<$length>
1199is C<undef>, then it goes till the end of the string. The flags can be
1200a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
1201C<IO::AIO::MS_SYNC>.
1202
1203=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1204
1205This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1206scalars.
1207
1208It touches (reads or writes) all memory pages in the specified
1209range inside the scalar. All caveats and parameters are the same
1210as for C<aio_msync>, above, except for flags, which must be either
1211C<0> (which reads all pages and ensures they are instantiated) or
1212C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
1213writing an octet from it, which dirties the page).
1214
1215=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1216
1217This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1218scalars.
1219
1220It reads in all the pages of the underlying storage into memory (if any)
1221and locks them, so they are not getting swapped/paged out or removed.
1222
1223If C<$length> is undefined, then the scalar will be locked till the end.
1224
1225On systems that do not implement C<mlock>, this function returns C<-1>
1226and sets errno to C<ENOSYS>.
1227
1228Note that the corresponding C<munlock> is synchronous and is
1229documented under L<MISCELLANEOUS FUNCTIONS>.
1230
1231Example: open a file, mmap and mlock it - both will be undone when
1232C<$data> gets destroyed.
1233
1234 open my $fh, "<", $path or die "$path: $!";
1235 my $data;
1236 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1237 aio_mlock $data; # mlock in background
1238
1239=item aio_mlockall $flags, $callback->($status)
1240
1241Calls the C<mlockall> function with the given C<$flags> (a combination of
1242C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1243
1244On systems that do not implement C<mlockall>, this function returns C<-1>
1245and sets errno to C<ENOSYS>.
1246
1247Note that the corresponding C<munlockall> is synchronous and is
1248documented under L<MISCELLANEOUS FUNCTIONS>.
1249
1250Example: asynchronously lock all current and future pages into memory.
1251
1252 aio_mlockall IO::AIO::MCL_FUTURE;
709 1253
710=item aio_group $callback->(...) 1254=item aio_group $callback->(...)
711 1255
712This is a very special aio request: Instead of doing something, it is a 1256This is a very special aio request: Instead of doing something, it is a
713container for other aio requests, which is useful if you want to bundle 1257container for other aio requests, which is useful if you want to bundle
751immense (it blocks a thread for a long time) so do not use this function 1295immense (it blocks a thread for a long time) so do not use this function
752except to put your application under artificial I/O pressure. 1296except to put your application under artificial I/O pressure.
753 1297
754=back 1298=back
755 1299
1300
1301=head2 IO::AIO::WD - multiple working directories
1302
1303Your process only has one current working directory, which is used by all
1304threads. This makes it hard to use relative paths (some other component
1305could call C<chdir> at any time, and it is hard to control when the path
1306will be used by IO::AIO).
1307
1308One solution for this is to always use absolute paths. This usually works,
1309but can be quite slow (the kernel has to walk the whole path on every
1310access), and can also be a hassle to implement.
1311
1312Newer POSIX systems have a number of functions (openat, fdopendir,
1313futimensat and so on) that make it possible to specify working directories
1314per operation.
1315
1316For portability, and because the clowns who "designed", or shall I write,
1317perpetrated this new interface were obviously half-drunk, this abstraction
1318cannot be perfect, though.
1319
1320IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1321object. This object stores the canonicalised, absolute version of the
1322path, and on systems that allow it, also a directory file descriptor.
1323
1324Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1325or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1326object and a pathname instead (or the IO::AIO::WD object alone, which
1327gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1328IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1329to that IO::AIO::WD object.
1330
1331For example, to get a wd object for F</etc> and then stat F<passwd>
1332inside, you would write:
1333
1334 aio_wd "/etc", sub {
1335 my $etcdir = shift;
1336
1337 # although $etcdir can be undef on error, there is generally no reason
1338 # to check for errors here, as aio_stat will fail with ENOENT
1339 # when $etcdir is undef.
1340
1341 aio_stat [$etcdir, "passwd"], sub {
1342 # yay
1343 };
1344 };
1345
1346That C<aio_wd> is a request and not a normal function shows that creating
1347an IO::AIO::WD object is itself a potentially blocking operation, which is
1348why it is done asynchronously.
1349
1350To stat the directory obtained with C<aio_wd> above, one could write
1351either of the following three request calls:
1352
1353 aio_lstat "/etc" , sub { ... # pathname as normal string
1354 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1355 aio_lstat $wd , sub { ... # shorthand for the previous
1356
1357As with normal pathnames, IO::AIO keeps a copy of the working directory
1358object and the pathname string, so you could write the following without
1359causing any issues due to C<$path> getting reused:
1360
1361 my $path = [$wd, undef];
1362
1363 for my $name (qw(abc def ghi)) {
1364 $path->[1] = $name;
1365 aio_stat $path, sub {
1366 # ...
1367 };
1368 }
1369
1370There are some caveats: when directories get renamed (or deleted), the
1371pathname string doesn't change, so will point to the new directory (or
1372nowhere at all), while the directory fd, if available on the system,
1373will still point to the original directory. Most functions accepting a
1374pathname will use the directory fd on newer systems, and the string on
1375older systems. Some functions (such as realpath) will always rely on the
1376string form of the pathname.
1377
1378So this fucntionality is mainly useful to get some protection against
1379C<chdir>, to easily get an absolute path out of a relative path for future
1380reference, and to speed up doing many operations in the same directory
1381(e.g. when stat'ing all files in a directory).
1382
1383The following functions implement this working directory abstraction:
1384
1385=over 4
1386
1387=item aio_wd $pathname, $callback->($wd)
1388
1389Asynchonously canonicalise the given pathname and convert it to an
1390IO::AIO::WD object representing it. If possible and supported on the
1391system, also open a directory fd to speed up pathname resolution relative
1392to this working directory.
1393
1394If something goes wrong, then C<undef> is passwd to the callback instead
1395of a working directory object and C<$!> is set appropriately. Since
1396passing C<undef> as working directory component of a pathname fails the
1397request with C<ENOENT>, there is often no need for error checking in the
1398C<aio_wd> callback, as future requests using the value will fail in the
1399expected way.
1400
1401If this call isn't available because your OS lacks it or it couldn't be
1402detected, it will be emulated by calling C<fsync> instead.
1403
1404=item IO::AIO::CWD
1405
1406This is a compiletime constant (object) that represents the process
1407current working directory.
1408
1409Specifying this object as working directory object for a pathname is as
1410if the pathname would be specified directly, without a directory object,
1411e.g., these calls are functionally identical:
1412
1413 aio_stat "somefile", sub { ... };
1414 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1415
1416=back
1417
1418
756=head2 IO::AIO::REQ CLASS 1419=head2 IO::AIO::REQ CLASS
757 1420
758All non-aggregate C<aio_*> functions return an object of this class when 1421All non-aggregate C<aio_*> functions return an object of this class when
759called in non-void context. 1422called in non-void context.
760 1423
763=item cancel $req 1426=item cancel $req
764 1427
765Cancels the request, if possible. Has the effect of skipping execution 1428Cancels the request, if possible. Has the effect of skipping execution
766when entering the B<execute> state and skipping calling the callback when 1429when entering the B<execute> state and skipping calling the callback when
767entering the the B<result> state, but will leave the request otherwise 1430entering the the B<result> state, but will leave the request otherwise
768untouched. That means that requests that currently execute will not be 1431untouched (with the exception of readdir). That means that requests that
769stopped and resources held by the request will not be freed prematurely. 1432currently execute will not be stopped and resources held by the request
1433will not be freed prematurely.
770 1434
771=item cb $req $callback->(...) 1435=item cb $req $callback->(...)
772 1436
773Replace (or simply set) the callback registered to the request. 1437Replace (or simply set) the callback registered to the request.
774 1438
825Their lifetime, simplified, looks like this: when they are empty, they 1489Their lifetime, simplified, looks like this: when they are empty, they
826will finish very quickly. If they contain only requests that are in the 1490will finish very quickly. If they contain only requests that are in the
827C<done> state, they will also finish. Otherwise they will continue to 1491C<done> state, they will also finish. Otherwise they will continue to
828exist. 1492exist.
829 1493
830That means after creating a group you have some time to add requests. And 1494That means after creating a group you have some time to add requests
831in the callbacks of those requests, you can add further requests to the 1495(precisely before the callback has been invoked, which is only done within
832group. And only when all those requests have finished will the the group 1496the C<poll_cb>). And in the callbacks of those requests, you can add
833itself finish. 1497further requests to the group. And only when all those requests have
1498finished will the the group itself finish.
834 1499
835=over 4 1500=over 4
836 1501
837=item add $grp ... 1502=item add $grp ...
838 1503
847=item $grp->cancel_subs 1512=item $grp->cancel_subs
848 1513
849Cancel all subrequests and clears any feeder, but not the group request 1514Cancel all subrequests and clears any feeder, but not the group request
850itself. Useful when you queued a lot of events but got a result early. 1515itself. Useful when you queued a lot of events but got a result early.
851 1516
1517The group request will finish normally (you cannot add requests to the
1518group).
1519
852=item $grp->result (...) 1520=item $grp->result (...)
853 1521
854Set the result value(s) that will be passed to the group callback when all 1522Set the result value(s) that will be passed to the group callback when all
855subrequests have finished and set thre groups errno to the current value 1523subrequests have finished and set the groups errno to the current value
856of errno (just like calling C<errno> without an error number). By default, 1524of errno (just like calling C<errno> without an error number). By default,
857no argument will be passed and errno is zero. 1525no argument will be passed and errno is zero.
858 1526
859=item $grp->errno ([$errno]) 1527=item $grp->errno ([$errno])
860 1528
871=item feed $grp $callback->($grp) 1539=item feed $grp $callback->($grp)
872 1540
873Sets a feeder/generator on this group: every group can have an attached 1541Sets a feeder/generator on this group: every group can have an attached
874generator that generates requests if idle. The idea behind this is that, 1542generator that generates requests if idle. The idea behind this is that,
875although you could just queue as many requests as you want in a group, 1543although you could just queue as many requests as you want in a group,
876this might starve other requests for a potentially long time. For 1544this might starve other requests for a potentially long time. For example,
877example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> 1545C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
878requests, delaying any later requests for a long time. 1546requests, delaying any later requests for a long time.
879 1547
880To avoid this, and allow incremental generation of requests, you can 1548To avoid this, and allow incremental generation of requests, you can
881instead a group and set a feeder on it that generates those requests. The 1549instead a group and set a feeder on it that generates those requests. The
882feed callback will be called whenever there are few enough (see C<limit>, 1550feed callback will be called whenever there are few enough (see C<limit>,
887not impose any limits). 1555not impose any limits).
888 1556
889If the feed does not queue more requests when called, it will be 1557If the feed does not queue more requests when called, it will be
890automatically removed from the group. 1558automatically removed from the group.
891 1559
892If the feed limit is C<0>, it will be set to C<2> automatically. 1560If the feed limit is C<0> when this method is called, it will be set to
1561C<2> automatically.
893 1562
894Example: 1563Example:
895 1564
896 # stat all files in @files, but only ever use four aio requests concurrently: 1565 # stat all files in @files, but only ever use four aio requests concurrently:
897 1566
909Sets the feeder limit for the group: The feeder will be called whenever 1578Sets the feeder limit for the group: The feeder will be called whenever
910the group contains less than this many requests. 1579the group contains less than this many requests.
911 1580
912Setting the limit to C<0> will pause the feeding process. 1581Setting the limit to C<0> will pause the feeding process.
913 1582
1583The default value for the limit is C<0>, but note that setting a feeder
1584automatically bumps it up to C<2>.
1585
914=back 1586=back
915 1587
916=head2 SUPPORT FUNCTIONS 1588=head2 SUPPORT FUNCTIONS
917 1589
918=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 1590=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
920=over 4 1592=over 4
921 1593
922=item $fileno = IO::AIO::poll_fileno 1594=item $fileno = IO::AIO::poll_fileno
923 1595
924Return the I<request result pipe file descriptor>. This filehandle must be 1596Return the I<request result pipe file descriptor>. This filehandle must be
925polled for reading by some mechanism outside this module (e.g. Event or 1597polled for reading by some mechanism outside this module (e.g. EV, Glib,
926select, see below or the SYNOPSIS). If the pipe becomes readable you have 1598select and so on, see below or the SYNOPSIS). If the pipe becomes readable
927to call C<poll_cb> to check the results. 1599you have to call C<poll_cb> to check the results.
928 1600
929See C<poll_cb> for an example. 1601See C<poll_cb> for an example.
930 1602
931=item IO::AIO::poll_cb 1603=item IO::AIO::poll_cb
932 1604
933Process some outstanding events on the result pipe. You have to call this 1605Process some outstanding events on the result pipe. You have to call
934regularly. Returns the number of events processed. Returns immediately 1606this regularly. Returns C<0> if all events could be processed (or there
935when no events are outstanding. The amount of events processed depends on 1607were no events to process), or C<-1> if it returned earlier for whatever
936the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1608reason. Returns immediately when no events are outstanding. The amount of
1609events processed depends on the settings of C<IO::AIO::max_poll_req> and
1610C<IO::AIO::max_poll_time>.
937 1611
938If not all requests were processed for whatever reason, the filehandle 1612If not all requests were processed for whatever reason, the filehandle
939will still be ready when C<poll_cb> returns. 1613will still be ready when C<poll_cb> returns, so normally you don't have to
1614do anything special to have it called later.
1615
1616Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1617ready, it can be beneficial to call this function from loops which submit
1618a lot of requests, to make sure the results get processed when they become
1619available and not just when the loop is finished and the event loop takes
1620over again. This function returns very fast when there are no outstanding
1621requests.
940 1622
941Example: Install an Event watcher that automatically calls 1623Example: Install an Event watcher that automatically calls
942IO::AIO::poll_cb with high priority: 1624IO::AIO::poll_cb with high priority (more examples can be found in the
1625SYNOPSIS section, at the top of this document):
943 1626
944 Event->io (fd => IO::AIO::poll_fileno, 1627 Event->io (fd => IO::AIO::poll_fileno,
945 poll => 'r', async => 1, 1628 poll => 'r', async => 1,
946 cb => \&IO::AIO::poll_cb); 1629 cb => \&IO::AIO::poll_cb);
1630
1631=item IO::AIO::poll_wait
1632
1633If there are any outstanding requests and none of them in the result
1634phase, wait till the result filehandle becomes ready for reading (simply
1635does a C<select> on the filehandle. This is useful if you want to
1636synchronously wait for some requests to finish).
1637
1638See C<nreqs> for an example.
1639
1640=item IO::AIO::poll
1641
1642Waits until some requests have been handled.
1643
1644Returns the number of requests processed, but is otherwise strictly
1645equivalent to:
1646
1647 IO::AIO::poll_wait, IO::AIO::poll_cb
1648
1649=item IO::AIO::flush
1650
1651Wait till all outstanding AIO requests have been handled.
1652
1653Strictly equivalent to:
1654
1655 IO::AIO::poll_wait, IO::AIO::poll_cb
1656 while IO::AIO::nreqs;
947 1657
948=item IO::AIO::max_poll_reqs $nreqs 1658=item IO::AIO::max_poll_reqs $nreqs
949 1659
950=item IO::AIO::max_poll_time $seconds 1660=item IO::AIO::max_poll_time $seconds
951 1661
976 # use a low priority so other tasks have priority 1686 # use a low priority so other tasks have priority
977 Event->io (fd => IO::AIO::poll_fileno, 1687 Event->io (fd => IO::AIO::poll_fileno,
978 poll => 'r', nice => 1, 1688 poll => 'r', nice => 1,
979 cb => &IO::AIO::poll_cb); 1689 cb => &IO::AIO::poll_cb);
980 1690
981=item IO::AIO::poll_wait 1691=back
982
983If there are any outstanding requests and none of them in the result
984phase, wait till the result filehandle becomes ready for reading (simply
985does a C<select> on the filehandle. This is useful if you want to
986synchronously wait for some requests to finish).
987
988See C<nreqs> for an example.
989
990=item IO::AIO::poll
991
992Waits until some requests have been handled.
993
994Returns the number of requests processed, but is otherwise strictly
995equivalent to:
996
997 IO::AIO::poll_wait, IO::AIO::poll_cb
998
999=item IO::AIO::flush
1000
1001Wait till all outstanding AIO requests have been handled.
1002
1003Strictly equivalent to:
1004
1005 IO::AIO::poll_wait, IO::AIO::poll_cb
1006 while IO::AIO::nreqs;
1007 1692
1008=head3 CONTROLLING THE NUMBER OF THREADS 1693=head3 CONTROLLING THE NUMBER OF THREADS
1694
1695=over
1009 1696
1010=item IO::AIO::min_parallel $nthreads 1697=item IO::AIO::min_parallel $nthreads
1011 1698
1012Set the minimum number of AIO threads to C<$nthreads>. The current 1699Set the minimum number of AIO threads to C<$nthreads>. The current
1013default is C<8>, which means eight asynchronous operations can execute 1700default is C<8>, which means eight asynchronous operations can execute
1041 1728
1042Under normal circumstances you don't need to call this function. 1729Under normal circumstances you don't need to call this function.
1043 1730
1044=item IO::AIO::max_idle $nthreads 1731=item IO::AIO::max_idle $nthreads
1045 1732
1046Limit the number of threads (default: 4) that are allowed to idle (i.e., 1733Limit the number of threads (default: 4) that are allowed to idle
1047threads that did not get a request to process within 10 seconds). That 1734(i.e., threads that did not get a request to process within the idle
1048means if a thread becomes idle while C<$nthreads> other threads are also 1735timeout (default: 10 seconds). That means if a thread becomes idle while
1049idle, it will free its resources and exit. 1736C<$nthreads> other threads are also idle, it will free its resources and
1737exit.
1050 1738
1051This is useful when you allow a large number of threads (e.g. 100 or 1000) 1739This is useful when you allow a large number of threads (e.g. 100 or 1000)
1052to allow for extremely high load situations, but want to free resources 1740to allow for extremely high load situations, but want to free resources
1053under normal circumstances (1000 threads can easily consume 30MB of RAM). 1741under normal circumstances (1000 threads can easily consume 30MB of RAM).
1054 1742
1055The default is probably ok in most situations, especially if thread 1743The default is probably ok in most situations, especially if thread
1056creation is fast. If thread creation is very slow on your system you might 1744creation is fast. If thread creation is very slow on your system you might
1057want to use larger values. 1745want to use larger values.
1058 1746
1747=item IO::AIO::idle_timeout $seconds
1748
1749Sets the minimum idle timeout (default 10) after which worker threads are
1750allowed to exit. SEe C<IO::AIO::max_idle>.
1751
1059=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1752=item IO::AIO::max_outstanding $maxreqs
1753
1754Sets the maximum number of outstanding requests to C<$nreqs>. If
1755you do queue up more than this number of requests, the next call to
1756C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1757C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1758longer exceeded.
1759
1760In other words, this setting does not enforce a queue limit, but can be
1761used to make poll functions block if the limit is exceeded.
1060 1762
1061This is a very bad function to use in interactive programs because it 1763This is a very bad function to use in interactive programs because it
1062blocks, and a bad way to reduce concurrency because it is inexact: Better 1764blocks, and a bad way to reduce concurrency because it is inexact: Better
1063use an C<aio_group> together with a feed callback. 1765use an C<aio_group> together with a feed callback.
1064 1766
1065Sets the maximum number of outstanding requests to C<$nreqs>. If you 1767It's main use is in scripts without an event loop - when you want to stat
1066to queue up more than this number of requests, the next call to the 1768a lot of files, you can write somehting like this:
1067C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1068function will block until the limit is no longer exceeded.
1069 1769
1070The default value is very large, so there is no practical limit on the 1770 IO::AIO::max_outstanding 32;
1071number of outstanding requests.
1072 1771
1073You can still queue as many requests as you want. Therefore, 1772 for my $path (...) {
1074C<max_oustsanding> is mainly useful in simple scripts (with low values) or 1773 aio_stat $path , ...;
1075as a stop gap to shield against fatal memory overflow (with large values). 1774 IO::AIO::poll_cb;
1775 }
1776
1777 IO::AIO::flush;
1778
1779The call to C<poll_cb> inside the loop will normally return instantly, but
1780as soon as more thna C<32> reqeusts are in-flight, it will block until
1781some requests have been handled. This keeps the loop from pushing a large
1782number of C<aio_stat> requests onto the queue.
1783
1784The default value for C<max_outstanding> is very large, so there is no
1785practical limit on the number of outstanding requests.
1786
1787=back
1076 1788
1077=head3 STATISTICAL INFORMATION 1789=head3 STATISTICAL INFORMATION
1790
1791=over
1078 1792
1079=item IO::AIO::nreqs 1793=item IO::AIO::nreqs
1080 1794
1081Returns the number of requests currently in the ready, execute or pending 1795Returns the number of requests currently in the ready, execute or pending
1082states (i.e. for which their callback has not been invoked yet). 1796states (i.e. for which their callback has not been invoked yet).
1096Returns the number of requests currently in the pending state (executed, 1810Returns the number of requests currently in the pending state (executed,
1097but not yet processed by poll_cb). 1811but not yet processed by poll_cb).
1098 1812
1099=back 1813=back
1100 1814
1815=head3 MISCELLANEOUS FUNCTIONS
1816
1817IO::AIO implements some functions that might be useful, but are not
1818asynchronous.
1819
1820=over 4
1821
1822=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1823
1824Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1825but is blocking (this makes most sense if you know the input data is
1826likely cached already and the output filehandle is set to non-blocking
1827operations).
1828
1829Returns the number of bytes copied, or C<-1> on error.
1830
1831=item IO::AIO::fadvise $fh, $offset, $len, $advice
1832
1833Simply calls the C<posix_fadvise> function (see its
1834manpage for details). The following advice constants are
1835available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1836C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1837C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1838
1839On systems that do not implement C<posix_fadvise>, this function returns
1840ENOSYS, otherwise the return value of C<posix_fadvise>.
1841
1842=item IO::AIO::madvise $scalar, $offset, $len, $advice
1843
1844Simply calls the C<posix_madvise> function (see its
1845manpage for details). The following advice constants are
1846available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1847C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1848
1849On systems that do not implement C<posix_madvise>, this function returns
1850ENOSYS, otherwise the return value of C<posix_madvise>.
1851
1852=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1853
1854Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1855$scalar (see its manpage for details). The following protect
1856constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1857C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1858
1859On systems that do not implement C<mprotect>, this function returns
1860ENOSYS, otherwise the return value of C<mprotect>.
1861
1862=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1863
1864Memory-maps a file (or anonymous memory range) and attaches it to the
1865given C<$scalar>, which will act like a string scalar.
1866
1867The only operations allowed on the scalar are C<substr>/C<vec> that don't
1868change the string length, and most read-only operations such as copying it
1869or searching it with regexes and so on.
1870
1871Anything else is unsafe and will, at best, result in memory leaks.
1872
1873The memory map associated with the C<$scalar> is automatically removed
1874when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
1875C<IO::AIO::munmap> functions are called.
1876
1877This calls the C<mmap>(2) function internally. See your system's manual
1878page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1879
1880The C<$length> must be larger than zero and smaller than the actual
1881filesize.
1882
1883C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1884C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1885
1886C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
1887C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
1888not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
1889(which is set to C<MAP_ANON> if your system only provides this
1890constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
1891C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1892C<IO::AIO::MAP_NONBLOCK>
1893
1894If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1895
1896C<$offset> is the offset from the start of the file - it generally must be
1897a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1898
1899Example:
1900
1901 use Digest::MD5;
1902 use IO::AIO;
1903
1904 open my $fh, "<verybigfile"
1905 or die "$!";
1906
1907 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1908 or die "verybigfile: $!";
1909
1910 my $fast_md5 = md5 $data;
1911
1912=item IO::AIO::munmap $scalar
1913
1914Removes a previous mmap and undefines the C<$scalar>.
1915
1916=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1917
1918Calls the C<munlock> function, undoing the effects of a previous
1919C<aio_mlock> call (see its description for details).
1920
1921=item IO::AIO::munlockall
1922
1923Calls the C<munlockall> function.
1924
1925On systems that do not implement C<munlockall>, this function returns
1926ENOSYS, otherwise the return value of C<munlockall>.
1927
1928=back
1929
1101=cut 1930=cut
1102 1931
1103# support function to convert a fd into a perl filehandle
1104sub _fd2fh {
1105 return undef if $_[0] < 0;
1106
1107 # try to generate nice filehandles
1108 my $sym = "IO::AIO::fd#$_[0]";
1109 local *$sym;
1110
1111 open *$sym, "+<&=$_[0]" # usually works under any unix
1112 or open *$sym, "<&=$_[0]" # cygwin needs this
1113 or open *$sym, ">&=$_[0]" # or this
1114 or return undef;
1115
1116 *$sym
1117}
1118
1119min_parallel 8; 1932min_parallel 8;
1120 1933
1121END { flush } 1934END { flush }
1122 1935
11231; 19361;
1124 1937
1938=head1 EVENT LOOP INTEGRATION
1939
1940It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
1941automatically into many event loops:
1942
1943 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1944 use AnyEvent::AIO;
1945
1946You can also integrate IO::AIO manually into many event loops, here are
1947some examples of how to do this:
1948
1949 # EV integration
1950 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1951
1952 # Event integration
1953 Event->io (fd => IO::AIO::poll_fileno,
1954 poll => 'r',
1955 cb => \&IO::AIO::poll_cb);
1956
1957 # Glib/Gtk2 integration
1958 add_watch Glib::IO IO::AIO::poll_fileno,
1959 in => sub { IO::AIO::poll_cb; 1 };
1960
1961 # Tk integration
1962 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1963 readable => \&IO::AIO::poll_cb);
1964
1965 # Danga::Socket integration
1966 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1967 \&IO::AIO::poll_cb);
1968
1125=head2 FORK BEHAVIOUR 1969=head2 FORK BEHAVIOUR
1126 1970
1127This module should do "the right thing" when the process using it forks: 1971Usage of pthreads in a program changes the semantics of fork
1972considerably. Specifically, only async-safe functions can be called after
1973fork. Perl doesn't know about this, so in general, you cannot call fork
1974with defined behaviour in perl if pthreads are involved. IO::AIO uses
1975pthreads, so this applies, but many other extensions and (for inexplicable
1976reasons) perl itself often is linked against pthreads, so this limitation
1977applies to quite a lot of perls.
1128 1978
1129Before the fork, IO::AIO enters a quiescent state where no requests 1979This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1130can be added in other threads and no results will be processed. After 1980only works in the process that loaded it. Forking is fully supported, but
1131the fork the parent simply leaves the quiescent state and continues 1981using IO::AIO in the child is not.
1132request/result processing, while the child frees the request/result queue
1133(so that the requests started before the fork will only be handled in the
1134parent). Threads will be started on demand until the limit set in the
1135parent process has been reached again.
1136 1982
1137In short: the parent will, after a short pause, continue as if fork had 1983You might get around by not I<using> IO::AIO before (or after)
1138not been called, while the child will act as if IO::AIO has not been used 1984forking. You could also try to call the L<IO::AIO::reinit> function in the
1139yet. 1985child:
1986
1987=over 4
1988
1989=item IO::AIO::reinit
1990
1991Abandons all current requests and I/O threads and simply reinitialises all
1992data structures. This is not an operation supported by any standards, but
1993happens to work on GNU/Linux and some newer BSD systems.
1994
1995The only reasonable use for this function is to call it after forking, if
1996C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
1997the process will result in undefined behaviour. Calling it at any time
1998will also result in any undefined (by POSIX) behaviour.
1999
2000=back
1140 2001
1141=head2 MEMORY USAGE 2002=head2 MEMORY USAGE
1142 2003
1143Per-request usage: 2004Per-request usage:
1144 2005
1146bytes of memory. In addition, stat requests need a stat buffer (possibly 2007bytes of memory. In addition, stat requests need a stat buffer (possibly
1147a few hundred bytes), readdir requires a result buffer and so on. Perl 2008a few hundred bytes), readdir requires a result buffer and so on. Perl
1148scalars and other data passed into aio requests will also be locked and 2009scalars and other data passed into aio requests will also be locked and
1149will consume memory till the request has entered the done state. 2010will consume memory till the request has entered the done state.
1150 2011
1151This is now awfully much, so queuing lots of requests is not usually a 2012This is not awfully much, so queuing lots of requests is not usually a
1152problem. 2013problem.
1153 2014
1154Per-thread usage: 2015Per-thread usage:
1155 2016
1156In the execution phase, some aio requests require more memory for 2017In the execution phase, some aio requests require more memory for
1161 2022
1162Known bugs will be fixed in the next release. 2023Known bugs will be fixed in the next release.
1163 2024
1164=head1 SEE ALSO 2025=head1 SEE ALSO
1165 2026
1166L<Coro::AIO>. 2027L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
2028more natural syntax.
1167 2029
1168=head1 AUTHOR 2030=head1 AUTHOR
1169 2031
1170 Marc Lehmann <schmorp@schmorp.de> 2032 Marc Lehmann <schmorp@schmorp.de>
1171 http://home.schmorp.de/ 2033 http://home.schmorp.de/

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