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Revision 1.5 by root, Sun Jul 10 21:04:24 2005 UTC vs.
Revision 1.27 by root, Tue Aug 16 22:22:18 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 = 1.1;
36 69
37 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink 70 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
38 aio_fsync aio_fdatasync aio_readahead); 71 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); 72 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
40 73
41 require XSLoader; 74 require XSLoader;
42 XSLoader::load IO::AIO, $VERSION; 75 XSLoader::load IO::AIO, $VERSION;
43} 76}
… …
46 79
47=head2 AIO FUNCTIONS 80=head2 AIO FUNCTIONS
48 81
49All the C<aio_*> calls are more or less thin wrappers around the syscall 82All the C<aio_*> calls are more or less thin wrappers around the syscall
50with the same name (sans C<aio_>). The arguments are similar or identical, 83with the same name (sans C<aio_>). The arguments are similar or identical,
51and they all accept an additional C<$callback> argument which must be 84and they all accept an additional (and optional) C<$callback> argument
52a code reference. This code reference will get called with the syscall 85which 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 86the 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 87perl, which usually delivers "false") as it's sole argument when the given
55been executed asynchronously. 88syscall has been executed asynchronously.
56 89
57All functions that expect a filehandle will also accept a file descriptor. 90All functions expecting a filehandle keep a copy of the filehandle
91internally until the request has finished.
58 92
59The filenames you pass to these routines I<must> be absolute. The reason 93The filenames you pass to these routines I<must> be absolute. The reason
60is that at the time the request is being executed, the current working 94for this is that at the time the request is being executed, the current
61directory could have changed. Alternatively, you can make sure that you 95working directory could have changed. Alternatively, you can make sure
62never change the current working directory. 96that you never change the current working directory.
63 97
64=over 4 98=over 4
65 99
66=item aio_open $pathname, $flags, $mode, $callback 100=item aio_open $pathname, $flags, $mode, $callback
67 101
… …
69created filehandle for the file. 103created filehandle for the file.
70 104
71The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 105The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
72for an explanation. 106for an explanation.
73 107
74The C<$mode> argument is a bitmask. See the C<Fcntl> module for a 108The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
75list. They are the same as used in C<sysopen>. 109list. They are the same as used by C<sysopen>.
110
111Likewise, C<$mode> specifies the mode of the newly created file, if it
112didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
113except that it is mandatory (i.e. use C<0> if you don't create new files,
114and C<0666> or C<0777> if you do).
76 115
77Example: 116Example:
78 117
79 aio_open "/etc/passwd", O_RDONLY, 0, sub { 118 aio_open "/etc/passwd", O_RDONLY, 0, sub {
80 if ($_[0]) { 119 if ($_[0]) {
… …
87 126
88=item aio_close $fh, $callback 127=item aio_close $fh, $callback
89 128
90Asynchronously close a file and call the callback with the result 129Asynchronously close a file and call the callback with the result
91code. I<WARNING:> although accepted, you should not pass in a perl 130code. I<WARNING:> although accepted, you should not pass in a perl
92filehandle here, as perl will likely close the file descriptor itself when 131filehandle here, as perl will likely close the file descriptor another
93the filehandle is destroyed. Normally, you can safely call perls C<close> 132time when the filehandle is destroyed. Normally, you can safely call perls
94or just let filehandles go out of scope. 133C<close> or just let filehandles go out of scope.
134
135This is supposed to be a bug in the API, so that might change. It's
136therefore best to avoid this function.
95 137
96=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 138=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
97 139
98=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 140=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
99 141
100Reads or writes C<length> bytes from the specified C<fh> and C<offset> 142Reads or writes C<length> bytes from the specified C<fh> and C<offset>
101into the scalar given by C<data> and offset C<dataoffset> and calls the 143into the scalar given by C<data> and offset C<dataoffset> and calls the
102callback without the actual number of bytes read (or -1 on error, just 144callback without the actual number of bytes read (or -1 on error, just
103like the syscall). 145like the syscall).
104 146
105Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at 147Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
106offset C<0> within the scalar: 148offset C<0> within the scalar:
107 149
108 aio_read $fh, 7, 15, $buffer, 0, sub { 150 aio_read $fh, 7, 15, $buffer, 0, sub {
109 $_[0] >= 0 or die "read error: $!"; 151 $_[0] > 0 or die "read error: $!";
110 print "read <$buffer>\n"; 152 print "read $_[0] bytes: <$buffer>\n";
111 }; 153 };
112 154
113=item aio_readahead $fh,$offset,$length, $callback 155=item aio_readahead $fh,$offset,$length, $callback
114 156
115Asynchronously reads the specified byte range into the page cache, using
116the C<readahead> syscall. If that syscall doesn't exist the status will be
117C<-1> and C<$!> is set to ENOSYS.
118
119readahead() populates the page cache with data from a file so that 157C<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<$offset> 158subsequent reads from that file will not block on disk I/O. The C<$offset>
121argument specifies the starting point from which data is to be read and 159argument specifies the starting point from which data is to be read and
122C<$length> specifies the number of bytes to be read. I/O is performed in 160C<$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 161whole 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 162and 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 163(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. 164file. The current file offset of the file is left unchanged.
165
166If that syscall doesn't exist (likely if your OS isn't Linux) it will be
167emulated by simply reading the data, which would have a similar effect.
127 168
128=item aio_stat $fh_or_path, $callback 169=item aio_stat $fh_or_path, $callback
129 170
130=item aio_lstat $fh, $callback 171=item aio_lstat $fh, $callback
131 172
… …
150=item aio_unlink $pathname, $callback 191=item aio_unlink $pathname, $callback
151 192
152Asynchronously unlink (delete) a file and call the callback with the 193Asynchronously unlink (delete) a file and call the callback with the
153result code. 194result code.
154 195
196=item aio_rmdir $pathname, $callback
197
198Asynchronously rmdir (delete) a directory and call the callback with the
199result code.
200
155=item aio_fsync $fh, $callback 201=item aio_fsync $fh, $callback
156 202
157Asynchronously call fsync on the given filehandle and call the callback 203Asynchronously call fsync on the given filehandle and call the callback
158with the fsync result code. 204with the fsync result code.
159 205
160=item aio_fdatasync $fh, $callback 206=item aio_fdatasync $fh, $callback
161 207
162Asynchronously call fdatasync on the given filehandle and call the 208Asynchronously call fdatasync on the given filehandle and call the
163callback with the fdatasync result code. 209callback with the fdatasync result code.
164 210
211If this call isn't available because your OS lacks it or it couldn't be
212detected, it will be emulated by calling C<fsync> instead.
213
165=back 214=back
166 215
167=head2 SUPPORT FUNCTIONS 216=head2 SUPPORT FUNCTIONS
168 217
169=over 4 218=over 4
170 219
171=item $fileno = IO::AIO::poll_fileno 220=item $fileno = IO::AIO::poll_fileno
172 221
173Return the I<request result pipe filehandle>. This filehandle must be 222Return the I<request result pipe file descriptor>. This filehandle must be
174polled for reading by some mechanism outside this module (e.g. Event 223polled 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 224select, see below or the SYNOPSIS). If the pipe becomes readable you have
176C<poll_cb> to check the results. 225to call C<poll_cb> to check the results.
177 226
178See C<poll_cb> for an example. 227See C<poll_cb> for an example.
179 228
180=item IO::AIO::poll_cb 229=item IO::AIO::poll_cb
181 230
182Process all outstanding events on the result pipe. You have to call this 231Process all outstanding events on the result pipe. You have to call this
183regularly. Returns the number of events processed. Returns immediately 232regularly. Returns the number of events processed. Returns immediately
184when no events are outstanding. 233when no events are outstanding.
185 234
186You can use Event to multiplex, e.g.: 235Example: Install an Event watcher that automatically calls
236IO::AIO::poll_cb with high priority:
187 237
188 Event->io (fd => IO::AIO::poll_fileno, 238 Event->io (fd => IO::AIO::poll_fileno,
189 poll => 'r', async => 1, 239 poll => 'r', async => 1,
190 cb => \&IO::AIO::poll_cb); 240 cb => \&IO::AIO::poll_cb);
191 241
192=item IO::AIO::poll_wait 242=item IO::AIO::poll_wait
193 243
194Wait till the result filehandle becomes ready for reading (simply does a 244Wait till the result filehandle becomes ready for reading (simply does a
195select on the filehandle. This is useful if you want to synchronously wait 245C<select> on the filehandle. This is useful if you want to synchronously wait
196for some requests to finish). 246for some requests to finish).
197 247
198See C<nreqs> for an example. 248See C<nreqs> for an example.
199 249
200=item IO::AIO::nreqs 250=item IO::AIO::nreqs
201 251
202Returns the number of requests currently outstanding. 252Returns the number of requests currently outstanding (i.e. for which their
253callback has not been invoked yet).
203 254
204Example: wait till there are no outstanding requests anymore: 255Example: wait till there are no outstanding requests anymore:
205 256
206 IO::AIO::poll_wait, IO::AIO::poll_cb 257 IO::AIO::poll_wait, IO::AIO::poll_cb
207 while IO::AIO::nreqs; 258 while IO::AIO::nreqs;
259
260=item IO::AIO::flush
261
262Wait till all outstanding AIO requests have been handled.
263
264Strictly equivalent to:
265
266 IO::AIO::poll_wait, IO::AIO::poll_cb
267 while IO::AIO::nreqs;
268
269=item IO::AIO::poll
270
271Waits until some requests have been handled.
272
273Strictly equivalent to:
274
275 IO::AIO::poll_wait, IO::AIO::poll_cb
276 if IO::AIO::nreqs;
208 277
209=item IO::AIO::min_parallel $nthreads 278=item IO::AIO::min_parallel $nthreads
210 279
211Set the minimum number of AIO threads to C<$nthreads>. The default is 280Set 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 281C<1>, which means a single asynchronous operation can be done at one time
… …
250 319
251# support function to convert a fd into a perl filehandle 320# support function to convert a fd into a perl filehandle
252sub _fd2fh { 321sub _fd2fh {
253 return undef if $_[0] < 0; 322 return undef if $_[0] < 0;
254 323
255 # try to be perl5.6-compatible 324 # try to generate nice filehandles
256 local *AIO_FH; 325 my $sym = "IO::AIO::fd#$_[0]";
257 open AIO_FH, "+<&=$_[0]" 326 local *$sym;
327
328 open *$sym, "+<&=$_[0]" # usually works under any unix
329 or open *$sym, "<&=$_[0]" # cygwin needs this
330 or open *$sym, ">&=$_[0]" # or this
258 or return undef; 331 or return undef;
259 332
260 *AIO_FH 333 *$sym
261} 334}
262 335
263min_parallel 4; 336min_parallel 4;
264 337
265END { 338END {
266 max_parallel 0; 339 max_parallel 0;
267} 340}
268 341
2691; 3421;
270 343
344=head2 FORK BEHAVIOUR
345
346IO::AIO handles all outstanding AIO requests before the fork, destroys all
347AIO threads, and recreates them in both the parent and the child after the
348fork.
349
350
271=head1 SEE ALSO 351=head1 SEE ALSO
272 352
273L<Coro>, L<Linux::AIO>. 353L<Coro>, L<Linux::AIO>.
274 354
275=head1 AUTHOR 355=head1 AUTHOR

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