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Revision 1.5 by root, Sun Jul 10 21:04:24 2005 UTC vs.
Revision 1.32 by root, Wed Aug 17 05:26:20 2005 UTC

… …
3IO::AIO - Asynchronous Input/Output 3IO::AIO - Asynchronous Input/Output
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8
9 aio_open "/etc/passwd", O_RDONLY, 0, sub {
10 my ($fh) = @_;
11 ...
12 };
13
14 aio_unlink "/tmp/file", sub { };
15
16 aio_read $fh, 30000, 1024, $buffer, 0, sub {
17 $_[0] > 0 or die "read error: $!";
18 };
19
20 # Event
21 Event->io (fd => IO::AIO::poll_fileno,
22 poll => 'r',
23 cb => \&IO::AIO::poll_cb);
24
25 # Glib/Gtk2
26 add_watch Glib::IO IO::AIO::poll_fileno,
27 in => sub { IO::AIO::poll_cb; 1 };
28
29 # Tk
30 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
31 readable => \&IO::AIO::poll_cb);
32
33 # Danga::Socket
34 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
35 \&IO::AIO::poll_cb);
36
8 37
9=head1 DESCRIPTION 38=head1 DESCRIPTION
10 39
11This module implements asynchronous I/O using whatever means your 40This module implements asynchronous I/O using whatever means your
12operating system supports. 41operating system supports.
… …
19not well-supported (Linux doesn't allow them on normal files currently, 48not well-supported (Linux doesn't allow them on normal files currently,
20for example), and they would only support aio_read and aio_write, so the 49for example), and they would only support aio_read and aio_write, so the
21remaining functionality would have to be implemented using threads anyway. 50remaining functionality would have to be implemented using threads anyway.
22 51
23Although the module will work with in the presence of other threads, it is 52Although the module will work with in the presence of other threads, it is
24currently not reentrant, so use appropriate locking yourself. 53currently not reentrant, so use appropriate locking yourself, always call
54C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
55C<aio_> functions) recursively.
25 56
26=cut 57=cut
27 58
28package IO::AIO; 59package IO::AIO;
29 60
61no warnings;
62
30use base 'Exporter'; 63use base 'Exporter';
31 64
32use Fcntl (); 65use Fcntl ();
33 66
34BEGIN { 67BEGIN {
35 $VERSION = 0.2; 68 $VERSION = 1.3;
69
36 70
37 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink 71 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
38 aio_fsync aio_fdatasync aio_readahead); 72 aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
39 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); 73 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
40 74
41 require XSLoader; 75 require XSLoader;
42 XSLoader::load IO::AIO, $VERSION; 76 XSLoader::load IO::AIO, $VERSION;
43} 77}
… …
46 80
47=head2 AIO FUNCTIONS 81=head2 AIO FUNCTIONS
48 82
49All the C<aio_*> calls are more or less thin wrappers around the syscall 83All the C<aio_*> calls are more or less thin wrappers around the syscall
50with the same name (sans C<aio_>). The arguments are similar or identical, 84with the same name (sans C<aio_>). The arguments are similar or identical,
51and they all accept an additional C<$callback> argument which must be 85and they all accept an additional (and optional) C<$callback> argument
52a code reference. This code reference will get called with the syscall 86which must be a code reference. This code reference will get called with
53return code (e.g. most syscalls return C<-1> on error, unlike perl, which 87the syscall return code (e.g. most syscalls return C<-1> on error, unlike
54usually delivers "false") as it's sole argument when the given syscall has 88perl, which usually delivers "false") as it's sole argument when the given
55been executed asynchronously. 89syscall has been executed asynchronously.
56 90
57All functions that expect a filehandle will also accept a file descriptor. 91All functions expecting a filehandle keep a copy of the filehandle
92internally until the request has finished.
58 93
59The filenames you pass to these routines I<must> be absolute. The reason 94The pathnames you pass to these routines I<must> be absolute and
60is that at the time the request is being executed, the current working 95encoded in byte form. The reason for the former is that at the time the
61directory could have changed. Alternatively, you can make sure that you 96request is being executed, the current working directory could have
97changed. Alternatively, you can make sure that you never change the
62never change the current working directory. 98current working directory.
99
100To encode pathnames to byte form, either make sure you either: a)
101always pass in filenames you got from outside (command line, readdir
102etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
103your pathnames to the locale (or other) encoding in effect in the user
104environment, d) use Glib::filename_from_unicode on unicode filenames or e)
105use something else.
63 106
64=over 4 107=over 4
65 108
66=item aio_open $pathname, $flags, $mode, $callback 109=item aio_open $pathname, $flags, $mode, $callback
67 110
… …
69created filehandle for the file. 112created filehandle for the file.
70 113
71The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 114The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
72for an explanation. 115for an explanation.
73 116
74The C<$mode> argument is a bitmask. See the C<Fcntl> module for a 117The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
75list. They are the same as used in C<sysopen>. 118list. They are the same as used by C<sysopen>.
119
120Likewise, C<$mode> specifies the mode of the newly created file, if it
121didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
122except that it is mandatory (i.e. use C<0> if you don't create new files,
123and C<0666> or C<0777> if you do).
76 124
77Example: 125Example:
78 126
79 aio_open "/etc/passwd", O_RDONLY, 0, sub { 127 aio_open "/etc/passwd", O_RDONLY, 0, sub {
80 if ($_[0]) { 128 if ($_[0]) {
… …
87 135
88=item aio_close $fh, $callback 136=item aio_close $fh, $callback
89 137
90Asynchronously close a file and call the callback with the result 138Asynchronously close a file and call the callback with the result
91code. I<WARNING:> although accepted, you should not pass in a perl 139code. I<WARNING:> although accepted, you should not pass in a perl
92filehandle here, as perl will likely close the file descriptor itself when 140filehandle here, as perl will likely close the file descriptor another
93the filehandle is destroyed. Normally, you can safely call perls C<close> 141time when the filehandle is destroyed. Normally, you can safely call perls
94or just let filehandles go out of scope. 142C<close> or just let filehandles go out of scope.
143
144This is supposed to be a bug in the API, so that might change. It's
145therefore best to avoid this function.
95 146
96=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 147=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
97 148
98=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 149=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
99 150
100Reads or writes C<length> bytes from the specified C<fh> and C<offset> 151Reads or writes C<length> bytes from the specified C<fh> and C<offset>
101into the scalar given by C<data> and offset C<dataoffset> and calls the 152into the scalar given by C<data> and offset C<dataoffset> and calls the
102callback without the actual number of bytes read (or -1 on error, just 153callback without the actual number of bytes read (or -1 on error, just
103like the syscall). 154like the syscall).
104 155
156The C<$data> scalar I<MUST NOT> be modified in any way while the request
157is outstanding. Modifying it can result in segfaults or WW3 (if the
158necessary/optional hardware is installed).
159
105Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at 160Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
106offset C<0> within the scalar: 161offset C<0> within the scalar:
107 162
108 aio_read $fh, 7, 15, $buffer, 0, sub { 163 aio_read $fh, 7, 15, $buffer, 0, sub {
109 $_[0] >= 0 or die "read error: $!"; 164 $_[0] > 0 or die "read error: $!";
110 print "read <$buffer>\n"; 165 print "read $_[0] bytes: <$buffer>\n";
111 }; 166 };
112 167
113=item aio_readahead $fh,$offset,$length, $callback 168=item aio_readahead $fh,$offset,$length, $callback
114 169
115Asynchronously reads the specified byte range into the page cache, using
116the C<readahead> syscall. If that syscall doesn't exist the status will be
117C<-1> and C<$!> is set to ENOSYS.
118
119readahead() populates the page cache with data from a file so that 170C<aio_readahead> populates the page cache with data from a file so that
120subsequent reads from that file will not block on disk I/O. The C<$offset> 171subsequent reads from that file will not block on disk I/O. The C<$offset>
121argument specifies the starting point from which data is to be read and 172argument specifies the starting point from which data is to be read and
122C<$length> specifies the number of bytes to be read. I/O is performed in 173C<$length> specifies the number of bytes to be read. I/O is performed in
123whole pages, so that offset is effectively rounded down to a page boundary 174whole pages, so that offset is effectively rounded down to a page boundary
124and bytes are read up to the next page boundary greater than or equal to 175and bytes are read up to the next page boundary greater than or equal to
125(off-set+length). aio_readahead() does not read beyond the end of the 176(off-set+length). C<aio_readahead> does not read beyond the end of the
126file. The current file offset of the file is left unchanged. 177file. The current file offset of the file is left unchanged.
178
179If that syscall doesn't exist (likely if your OS isn't Linux) it will be
180emulated by simply reading the data, which would have a similar effect.
127 181
128=item aio_stat $fh_or_path, $callback 182=item aio_stat $fh_or_path, $callback
129 183
130=item aio_lstat $fh, $callback 184=item aio_lstat $fh, $callback
131 185
… …
150=item aio_unlink $pathname, $callback 204=item aio_unlink $pathname, $callback
151 205
152Asynchronously unlink (delete) a file and call the callback with the 206Asynchronously unlink (delete) a file and call the callback with the
153result code. 207result code.
154 208
209=item aio_rmdir $pathname, $callback
210
211Asynchronously rmdir (delete) a directory and call the callback with the
212result code.
213
155=item aio_fsync $fh, $callback 214=item aio_fsync $fh, $callback
156 215
157Asynchronously call fsync on the given filehandle and call the callback 216Asynchronously call fsync on the given filehandle and call the callback
158with the fsync result code. 217with the fsync result code.
159 218
160=item aio_fdatasync $fh, $callback 219=item aio_fdatasync $fh, $callback
161 220
162Asynchronously call fdatasync on the given filehandle and call the 221Asynchronously call fdatasync on the given filehandle and call the
163callback with the fdatasync result code. 222callback with the fdatasync result code.
164 223
224If this call isn't available because your OS lacks it or it couldn't be
225detected, it will be emulated by calling C<fsync> instead.
226
165=back 227=back
166 228
167=head2 SUPPORT FUNCTIONS 229=head2 SUPPORT FUNCTIONS
168 230
169=over 4 231=over 4
170 232
171=item $fileno = IO::AIO::poll_fileno 233=item $fileno = IO::AIO::poll_fileno
172 234
173Return the I<request result pipe filehandle>. This filehandle must be 235Return the I<request result pipe file descriptor>. This filehandle must be
174polled for reading by some mechanism outside this module (e.g. Event 236polled for reading by some mechanism outside this module (e.g. Event or
175or select, see below). If the pipe becomes readable you have to call 237select, see below or the SYNOPSIS). If the pipe becomes readable you have
176C<poll_cb> to check the results. 238to call C<poll_cb> to check the results.
177 239
178See C<poll_cb> for an example. 240See C<poll_cb> for an example.
179 241
180=item IO::AIO::poll_cb 242=item IO::AIO::poll_cb
181 243
182Process all outstanding events on the result pipe. You have to call this 244Process all outstanding events on the result pipe. You have to call this
183regularly. Returns the number of events processed. Returns immediately 245regularly. Returns the number of events processed. Returns immediately
184when no events are outstanding. 246when no events are outstanding.
185 247
186You can use Event to multiplex, e.g.: 248Example: Install an Event watcher that automatically calls
249IO::AIO::poll_cb with high priority:
187 250
188 Event->io (fd => IO::AIO::poll_fileno, 251 Event->io (fd => IO::AIO::poll_fileno,
189 poll => 'r', async => 1, 252 poll => 'r', async => 1,
190 cb => \&IO::AIO::poll_cb); 253 cb => \&IO::AIO::poll_cb);
191 254
192=item IO::AIO::poll_wait 255=item IO::AIO::poll_wait
193 256
194Wait till the result filehandle becomes ready for reading (simply does a 257Wait till the result filehandle becomes ready for reading (simply does a
195select on the filehandle. This is useful if you want to synchronously wait 258C<select> on the filehandle. This is useful if you want to synchronously wait
196for some requests to finish). 259for some requests to finish).
197 260
198See C<nreqs> for an example. 261See C<nreqs> for an example.
199 262
200=item IO::AIO::nreqs 263=item IO::AIO::nreqs
201 264
202Returns the number of requests currently outstanding. 265Returns the number of requests currently outstanding (i.e. for which their
266callback has not been invoked yet).
203 267
204Example: wait till there are no outstanding requests anymore: 268Example: wait till there are no outstanding requests anymore:
205 269
206 IO::AIO::poll_wait, IO::AIO::poll_cb 270 IO::AIO::poll_wait, IO::AIO::poll_cb
207 while IO::AIO::nreqs; 271 while IO::AIO::nreqs;
272
273=item IO::AIO::flush
274
275Wait till all outstanding AIO requests have been handled.
276
277Strictly equivalent to:
278
279 IO::AIO::poll_wait, IO::AIO::poll_cb
280 while IO::AIO::nreqs;
281
282=item IO::AIO::poll
283
284Waits until some requests have been handled.
285
286Strictly equivalent to:
287
288 IO::AIO::poll_wait, IO::AIO::poll_cb
289 if IO::AIO::nreqs;
208 290
209=item IO::AIO::min_parallel $nthreads 291=item IO::AIO::min_parallel $nthreads
210 292
211Set the minimum number of AIO threads to C<$nthreads>. The default is 293Set the minimum number of AIO threads to C<$nthreads>. The default is
212C<1>, which means a single asynchronous operation can be done at one time 294C<1>, which means a single asynchronous operation can be done at one time
… …
250 332
251# support function to convert a fd into a perl filehandle 333# support function to convert a fd into a perl filehandle
252sub _fd2fh { 334sub _fd2fh {
253 return undef if $_[0] < 0; 335 return undef if $_[0] < 0;
254 336
255 # try to be perl5.6-compatible 337 # try to generate nice filehandles
256 local *AIO_FH; 338 my $sym = "IO::AIO::fd#$_[0]";
257 open AIO_FH, "+<&=$_[0]" 339 local *$sym;
340
341 open *$sym, "+<&=$_[0]" # usually works under any unix
342 or open *$sym, "<&=$_[0]" # cygwin needs this
343 or open *$sym, ">&=$_[0]" # or this
258 or return undef; 344 or return undef;
259 345
260 *AIO_FH 346 *$sym
261} 347}
262 348
263min_parallel 4; 349min_parallel 4;
264 350
265END { 351END {
266 max_parallel 0; 352 max_parallel 0;
267} 353}
268 354
2691; 3551;
270 356
357=head2 FORK BEHAVIOUR
358
359Before the fork IO::AIO enters a quiescent state where no requests can be
360added in other threads and no results will be processed. After the fork
361the parent simply leaves the quiescent state and continues request/result
362processing, while the child clears the request/result queue and starts the
363same number of threads as were in use by the parent.
364
271=head1 SEE ALSO 365=head1 SEE ALSO
272 366
273L<Coro>, L<Linux::AIO>. 367L<Coro>, L<Linux::AIO>.
274 368
275=head1 AUTHOR 369=head1 AUTHOR

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