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Revision 1.5 by root, Sun Jul 10 21:04:24 2005 UTC vs.
Revision 1.29 by root, Wed Aug 17 04:47:02 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 = 1.2;
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 pathnames you pass to these routines I<must> be absolute and
60is that at the time the request is being executed, the current working 94encoded 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 95request is being executed, the current working directory could have
96changed. Alternatively, you can make sure that you never change the
62never change the current working directory. 97current working directory.
98
99To encode pathnames to byte form, either make sure you either: a)
100always pass in filenames you got from outside (command line, readdir
101etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
102your pathnames to the locale (or other) encoding in effect in the user
103environment, d) use Glib::filename_from_unicode on unicode filenames or e)
104use something else.
63 105
64=over 4 106=over 4
65 107
66=item aio_open $pathname, $flags, $mode, $callback 108=item aio_open $pathname, $flags, $mode, $callback
67 109
… …
69created filehandle for the file. 111created filehandle for the file.
70 112
71The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 113The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
72for an explanation. 114for an explanation.
73 115
74The C<$mode> argument is a bitmask. See the C<Fcntl> module for a 116The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
75list. They are the same as used in C<sysopen>. 117list. They are the same as used by C<sysopen>.
118
119Likewise, C<$mode> specifies the mode of the newly created file, if it
120didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
121except that it is mandatory (i.e. use C<0> if you don't create new files,
122and C<0666> or C<0777> if you do).
76 123
77Example: 124Example:
78 125
79 aio_open "/etc/passwd", O_RDONLY, 0, sub { 126 aio_open "/etc/passwd", O_RDONLY, 0, sub {
80 if ($_[0]) { 127 if ($_[0]) {
… …
87 134
88=item aio_close $fh, $callback 135=item aio_close $fh, $callback
89 136
90Asynchronously close a file and call the callback with the result 137Asynchronously close a file and call the callback with the result
91code. I<WARNING:> although accepted, you should not pass in a perl 138code. I<WARNING:> although accepted, you should not pass in a perl
92filehandle here, as perl will likely close the file descriptor itself when 139filehandle here, as perl will likely close the file descriptor another
93the filehandle is destroyed. Normally, you can safely call perls C<close> 140time when the filehandle is destroyed. Normally, you can safely call perls
94or just let filehandles go out of scope. 141C<close> or just let filehandles go out of scope.
142
143This is supposed to be a bug in the API, so that might change. It's
144therefore best to avoid this function.
95 145
96=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 146=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
97 147
98=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 148=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
99 149
100Reads or writes C<length> bytes from the specified C<fh> and C<offset> 150Reads or writes C<length> bytes from the specified C<fh> and C<offset>
101into the scalar given by C<data> and offset C<dataoffset> and calls the 151into the scalar given by C<data> and offset C<dataoffset> and calls the
102callback without the actual number of bytes read (or -1 on error, just 152callback without the actual number of bytes read (or -1 on error, just
103like the syscall). 153like the syscall).
104 154
105Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at 155Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
106offset C<0> within the scalar: 156offset C<0> within the scalar:
107 157
108 aio_read $fh, 7, 15, $buffer, 0, sub { 158 aio_read $fh, 7, 15, $buffer, 0, sub {
109 $_[0] >= 0 or die "read error: $!"; 159 $_[0] > 0 or die "read error: $!";
110 print "read <$buffer>\n"; 160 print "read $_[0] bytes: <$buffer>\n";
111 }; 161 };
112 162
113=item aio_readahead $fh,$offset,$length, $callback 163=item aio_readahead $fh,$offset,$length, $callback
114 164
115Asynchronously reads the specified byte range into the page cache, using
116the C<readahead> syscall. If that syscall doesn't exist the status will be
117C<-1> and C<$!> is set to ENOSYS.
118
119readahead() populates the page cache with data from a file so that 165C<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<$offset> 166subsequent reads from that file will not block on disk I/O. The C<$offset>
121argument specifies the starting point from which data is to be read and 167argument specifies the starting point from which data is to be read and
122C<$length> specifies the number of bytes to be read. I/O is performed in 168C<$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 169whole 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 170and 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 171(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. 172file. The current file offset of the file is left unchanged.
173
174If that syscall doesn't exist (likely if your OS isn't Linux) it will be
175emulated by simply reading the data, which would have a similar effect.
127 176
128=item aio_stat $fh_or_path, $callback 177=item aio_stat $fh_or_path, $callback
129 178
130=item aio_lstat $fh, $callback 179=item aio_lstat $fh, $callback
131 180
… …
150=item aio_unlink $pathname, $callback 199=item aio_unlink $pathname, $callback
151 200
152Asynchronously unlink (delete) a file and call the callback with the 201Asynchronously unlink (delete) a file and call the callback with the
153result code. 202result code.
154 203
204=item aio_rmdir $pathname, $callback
205
206Asynchronously rmdir (delete) a directory and call the callback with the
207result code.
208
155=item aio_fsync $fh, $callback 209=item aio_fsync $fh, $callback
156 210
157Asynchronously call fsync on the given filehandle and call the callback 211Asynchronously call fsync on the given filehandle and call the callback
158with the fsync result code. 212with the fsync result code.
159 213
160=item aio_fdatasync $fh, $callback 214=item aio_fdatasync $fh, $callback
161 215
162Asynchronously call fdatasync on the given filehandle and call the 216Asynchronously call fdatasync on the given filehandle and call the
163callback with the fdatasync result code. 217callback with the fdatasync result code.
164 218
219If this call isn't available because your OS lacks it or it couldn't be
220detected, it will be emulated by calling C<fsync> instead.
221
165=back 222=back
166 223
167=head2 SUPPORT FUNCTIONS 224=head2 SUPPORT FUNCTIONS
168 225
169=over 4 226=over 4
170 227
171=item $fileno = IO::AIO::poll_fileno 228=item $fileno = IO::AIO::poll_fileno
172 229
173Return the I<request result pipe filehandle>. This filehandle must be 230Return the I<request result pipe file descriptor>. This filehandle must be
174polled for reading by some mechanism outside this module (e.g. Event 231polled 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 232select, see below or the SYNOPSIS). If the pipe becomes readable you have
176C<poll_cb> to check the results. 233to call C<poll_cb> to check the results.
177 234
178See C<poll_cb> for an example. 235See C<poll_cb> for an example.
179 236
180=item IO::AIO::poll_cb 237=item IO::AIO::poll_cb
181 238
182Process all outstanding events on the result pipe. You have to call this 239Process all outstanding events on the result pipe. You have to call this
183regularly. Returns the number of events processed. Returns immediately 240regularly. Returns the number of events processed. Returns immediately
184when no events are outstanding. 241when no events are outstanding.
185 242
186You can use Event to multiplex, e.g.: 243Example: Install an Event watcher that automatically calls
244IO::AIO::poll_cb with high priority:
187 245
188 Event->io (fd => IO::AIO::poll_fileno, 246 Event->io (fd => IO::AIO::poll_fileno,
189 poll => 'r', async => 1, 247 poll => 'r', async => 1,
190 cb => \&IO::AIO::poll_cb); 248 cb => \&IO::AIO::poll_cb);
191 249
192=item IO::AIO::poll_wait 250=item IO::AIO::poll_wait
193 251
194Wait till the result filehandle becomes ready for reading (simply does a 252Wait till the result filehandle becomes ready for reading (simply does a
195select on the filehandle. This is useful if you want to synchronously wait 253C<select> on the filehandle. This is useful if you want to synchronously wait
196for some requests to finish). 254for some requests to finish).
197 255
198See C<nreqs> for an example. 256See C<nreqs> for an example.
199 257
200=item IO::AIO::nreqs 258=item IO::AIO::nreqs
201 259
202Returns the number of requests currently outstanding. 260Returns the number of requests currently outstanding (i.e. for which their
261callback has not been invoked yet).
203 262
204Example: wait till there are no outstanding requests anymore: 263Example: wait till there are no outstanding requests anymore:
205 264
206 IO::AIO::poll_wait, IO::AIO::poll_cb 265 IO::AIO::poll_wait, IO::AIO::poll_cb
207 while IO::AIO::nreqs; 266 while IO::AIO::nreqs;
267
268=item IO::AIO::flush
269
270Wait till all outstanding AIO requests have been handled.
271
272Strictly equivalent to:
273
274 IO::AIO::poll_wait, IO::AIO::poll_cb
275 while IO::AIO::nreqs;
276
277=item IO::AIO::poll
278
279Waits until some requests have been handled.
280
281Strictly equivalent to:
282
283 IO::AIO::poll_wait, IO::AIO::poll_cb
284 if IO::AIO::nreqs;
208 285
209=item IO::AIO::min_parallel $nthreads 286=item IO::AIO::min_parallel $nthreads
210 287
211Set the minimum number of AIO threads to C<$nthreads>. The default is 288Set 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 289C<1>, which means a single asynchronous operation can be done at one time
… …
250 327
251# support function to convert a fd into a perl filehandle 328# support function to convert a fd into a perl filehandle
252sub _fd2fh { 329sub _fd2fh {
253 return undef if $_[0] < 0; 330 return undef if $_[0] < 0;
254 331
255 # try to be perl5.6-compatible 332 # try to generate nice filehandles
256 local *AIO_FH; 333 my $sym = "IO::AIO::fd#$_[0]";
257 open AIO_FH, "+<&=$_[0]" 334 local *$sym;
335
336 open *$sym, "+<&=$_[0]" # usually works under any unix
337 or open *$sym, "<&=$_[0]" # cygwin needs this
338 or open *$sym, ">&=$_[0]" # or this
258 or return undef; 339 or return undef;
259 340
260 *AIO_FH 341 *$sym
261} 342}
262 343
263min_parallel 4; 344min_parallel 4;
264 345
265END { 346END {
266 max_parallel 0; 347 max_parallel 0;
267} 348}
268 349
2691; 3501;
270 351
352=head2 FORK BEHAVIOUR
353
354Before the fork IO::AIO first handles all outstanding requests - if other
355threads add requests during this period, this time is prolonged. It then
356enters a quiescent state where no requests can be added in other threads
357and no results will be processed. After the fork the parent simply leaves
358the quiescent state and continues request processing, while the child will
359free the request and result queue and start the same number of threads as
360were in use by the parent.
361
271=head1 SEE ALSO 362=head1 SEE ALSO
272 363
273L<Coro>, L<Linux::AIO>. 364L<Coro>, L<Linux::AIO>.
274 365
275=head1 AUTHOR 366=head1 AUTHOR

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