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12 }; 12 };
13 13
14 aio_unlink "/tmp/file", sub { }; 14 aio_unlink "/tmp/file", sub { };
15 15
16 aio_read $fh, 30000, 1024, $buffer, 0, sub { 16 aio_read $fh, 30000, 1024, $buffer, 0, sub {
17 $_[0] >= 0 or die "read error: $!"; 17 $_[0] > 0 or die "read error: $!";
18 }; 18 };
19 19
20 # Event 20 # Event
21 Event->io (fd => IO::AIO::poll_fileno, 21 Event->io (fd => IO::AIO::poll_fileno,
22 poll => 'r', async => 1, 22 poll => 'r',
23 cb => \&IO::AIO::poll_cb); 23 cb => \&IO::AIO::poll_cb);
24 24
25 # Glib/Gtk2 25 # Glib/Gtk2
26 add_watch Glib::IO IO::AIO::poll_fileno, 26 add_watch Glib::IO IO::AIO::poll_fileno,
27 \&IO::AIO::poll_cb; 27 in => sub { IO::AIO::poll_cb; 1 };
28 28
29 # Tk 29 # Tk
30 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", 30 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
31 readable => \&IO::AIO::poll_cb); 31 readable => \&IO::AIO::poll_cb);
32
33 # Danga::Socket
34 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
35 \&IO::AIO::poll_cb);
36
32 37
33=head1 DESCRIPTION 38=head1 DESCRIPTION
34 39
35This module implements asynchronous I/O using whatever means your 40This module implements asynchronous I/O using whatever means your
36operating system supports. 41operating system supports.
… …
43not well-supported (Linux doesn't allow them on normal files currently, 48not well-supported (Linux doesn't allow them on normal files currently,
44for 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
45remaining functionality would have to be implemented using threads anyway. 50remaining functionality would have to be implemented using threads anyway.
46 51
47Although 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
48currently 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.
49 56
50=cut 57=cut
51 58
52package IO::AIO; 59package IO::AIO;
53 60
61no warnings;
62
54use base 'Exporter'; 63use base 'Exporter';
55 64
56use Fcntl (); 65use Fcntl ();
57 66
58BEGIN { 67BEGIN {
59 $VERSION = 0.2; 68 $VERSION = 1.6;
60 69
61 @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
62 aio_fsync aio_fdatasync aio_readahead); 71 aio_rmdir aio_readdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
63 @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);
64 73
65 require XSLoader; 74 require XSLoader;
66 XSLoader::load IO::AIO, $VERSION; 75 XSLoader::load IO::AIO, $VERSION;
67} 76}
… …
70 79
71=head2 AIO FUNCTIONS 80=head2 AIO FUNCTIONS
72 81
73All the C<aio_*> calls are more or less thin wrappers around the syscall 82All the C<aio_*> calls are more or less thin wrappers around the syscall
74with the same name (sans C<aio_>). The arguments are similar or identical, 83with the same name (sans C<aio_>). The arguments are similar or identical,
75and they all accept an additional C<$callback> argument which must be 84and they all accept an additional (and optional) C<$callback> argument
76a code reference. This code reference will get called with the syscall 85which must be a code reference. This code reference will get called with
77return 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
78usually 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
79been executed asynchronously. 88syscall has been executed asynchronously.
80 89
81All 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.
82 92
83The filenames you pass to these routines I<must> be absolute. The reason 93The pathnames you pass to these routines I<must> be absolute and
84is 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
85directory 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
86never 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.
87 105
88=over 4 106=over 4
89 107
90=item aio_open $pathname, $flags, $mode, $callback 108=item aio_open $pathname, $flags, $mode, $callback
91 109
… …
93created filehandle for the file. 111created filehandle for the file.
94 112
95The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 113The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
96for an explanation. 114for an explanation.
97 115
98The C<$mode> argument is a bitmask. See the C<Fcntl> module for a 116The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
99list. They are the same as used in C<sysopen>. 117list. They are the same as used by C<sysopen>.
118
119Likewise, C<$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).
100 123
101Example: 124Example:
102 125
103 aio_open "/etc/passwd", O_RDONLY, 0, sub { 126 aio_open "/etc/passwd", O_RDONLY, 0, sub {
104 if ($_[0]) { 127 if ($_[0]) {
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111 134
112=item aio_close $fh, $callback 135=item aio_close $fh, $callback
113 136
114Asynchronously close a file and call the callback with the result 137Asynchronously close a file and call the callback with the result
115code. I<WARNING:> although accepted, you should not pass in a perl 138code. I<WARNING:> although accepted, you should not pass in a perl
116filehandle here, as perl will likely close the file descriptor itself when 139filehandle here, as perl will likely close the file descriptor another
117the filehandle is destroyed. Normally, you can safely call perls C<close> 140time when the filehandle is destroyed. Normally, you can safely call perls
118or 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.
119 145
120=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 146=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
121 147
122=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 148=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
123 149
124Reads or writes C<length> bytes from the specified C<fh> and C<offset> 150Reads or writes C<length> bytes from the specified C<fh> and C<offset>
125into the scalar given by C<data> and offset C<dataoffset> and calls the 151into the scalar given by C<data> and offset C<dataoffset> and calls the
126callback without the actual number of bytes read (or -1 on error, just 152callback without the actual number of bytes read (or -1 on error, just
127like the syscall). 153like the syscall).
128 154
155The C<$data> scalar I<MUST NOT> be modified in any way while the request
156is outstanding. Modifying it can result in segfaults or WW3 (if the
157necessary/optional hardware is installed).
158
129Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at 159Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
130offset C<0> within the scalar: 160offset C<0> within the scalar:
131 161
132 aio_read $fh, 7, 15, $buffer, 0, sub { 162 aio_read $fh, 7, 15, $buffer, 0, sub {
133 $_[0] >= 0 or die "read error: $!"; 163 $_[0] > 0 or die "read error: $!";
134 print "read <$buffer>\n"; 164 print "read $_[0] bytes: <$buffer>\n";
135 }; 165 };
136 166
167=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback
168
169Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
170reading at byte offset C<$in_offset>, and starts writing at the current
171file offset of C<$out_fh>. Because of that, it is not safe to issue more
172than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
173other.
174
175This call tries to make use of a native C<sendfile> syscall to provide
176zero-copy operation. For this to work, C<$out_fh> should refer to a
177socket, and C<$in_fh> should refer to mmap'able file.
178
179If the native sendfile call fails or is not implemented, it will be
180emulated, so you can call C<aio_sendfile> on any type of filehandle
181regardless of the limitations of the operating system.
182
183Please note, however, that C<aio_sendfile> can read more bytes from
184C<$in_fh> than are written, and there is no way to find out how many
185bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
186provides the number of bytes written to C<$out_fh>. Only if the result
187value equals C<$length> one can assume that C<$length> bytes have been
188read.
189
137=item aio_readahead $fh,$offset,$length, $callback 190=item aio_readahead $fh,$offset,$length, $callback
138 191
139Asynchronously reads the specified byte range into the page cache, using
140the C<readahead> syscall. If that syscall doesn't exist the status will be
141C<-1> and C<$!> is set to ENOSYS.
142
143readahead() populates the page cache with data from a file so that 192C<aio_readahead> populates the page cache with data from a file so that
144subsequent reads from that file will not block on disk I/O. The C<$offset> 193subsequent reads from that file will not block on disk I/O. The C<$offset>
145argument specifies the starting point from which data is to be read and 194argument specifies the starting point from which data is to be read and
146C<$length> specifies the number of bytes to be read. I/O is performed in 195C<$length> specifies the number of bytes to be read. I/O is performed in
147whole pages, so that offset is effectively rounded down to a page boundary 196whole pages, so that offset is effectively rounded down to a page boundary
148and bytes are read up to the next page boundary greater than or equal to 197and bytes are read up to the next page boundary greater than or equal to
149(off-set+length). aio_readahead() does not read beyond the end of the 198(off-set+length). C<aio_readahead> does not read beyond the end of the
150file. The current file offset of the file is left unchanged. 199file. The current file offset of the file is left unchanged.
200
201If that syscall doesn't exist (likely if your OS isn't Linux) it will be
202emulated by simply reading the data, which would have a similar effect.
151 203
152=item aio_stat $fh_or_path, $callback 204=item aio_stat $fh_or_path, $callback
153 205
154=item aio_lstat $fh, $callback 206=item aio_lstat $fh, $callback
155 207
… …
174=item aio_unlink $pathname, $callback 226=item aio_unlink $pathname, $callback
175 227
176Asynchronously unlink (delete) a file and call the callback with the 228Asynchronously unlink (delete) a file and call the callback with the
177result code. 229result code.
178 230
231=item aio_rmdir $pathname, $callback
232
233Asynchronously rmdir (delete) a directory and call the callback with the
234result code.
235
236=item aio_readdir $pathname $callback
237
238Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
239directory (i.e. opendir + readdir + closedir). The entries will not be
240sorted, and will B<NOT> include the C<.> and C<..> entries.
241
242The callback a single argument which is either C<undef> or an array-ref
243with the filenames.
244
179=item aio_fsync $fh, $callback 245=item aio_fsync $fh, $callback
180 246
181Asynchronously call fsync on the given filehandle and call the callback 247Asynchronously call fsync on the given filehandle and call the callback
182with the fsync result code. 248with the fsync result code.
183 249
184=item aio_fdatasync $fh, $callback 250=item aio_fdatasync $fh, $callback
185 251
186Asynchronously call fdatasync on the given filehandle and call the 252Asynchronously call fdatasync on the given filehandle and call the
187callback with the fdatasync result code. 253callback with the fdatasync result code.
188 254
255If this call isn't available because your OS lacks it or it couldn't be
256detected, it will be emulated by calling C<fsync> instead.
257
189=back 258=back
190 259
191=head2 SUPPORT FUNCTIONS 260=head2 SUPPORT FUNCTIONS
192 261
193=over 4 262=over 4
194 263
195=item $fileno = IO::AIO::poll_fileno 264=item $fileno = IO::AIO::poll_fileno
196 265
197Return the I<request result pipe filehandle>. This filehandle must be 266Return the I<request result pipe file descriptor>. This filehandle must be
198polled for reading by some mechanism outside this module (e.g. Event 267polled for reading by some mechanism outside this module (e.g. Event or
199or select, see below). If the pipe becomes readable you have to call 268select, see below or the SYNOPSIS). If the pipe becomes readable you have
200C<poll_cb> to check the results. 269to call C<poll_cb> to check the results.
201 270
202See C<poll_cb> for an example. 271See C<poll_cb> for an example.
203 272
204=item IO::AIO::poll_cb 273=item IO::AIO::poll_cb
205 274
206Process all outstanding events on the result pipe. You have to call this 275Process all outstanding events on the result pipe. You have to call this
207regularly. Returns the number of events processed. Returns immediately 276regularly. Returns the number of events processed. Returns immediately
208when no events are outstanding. 277when no events are outstanding.
209 278
210You can use Event to multiplex, e.g.: 279Example: Install an Event watcher that automatically calls
280IO::AIO::poll_cb with high priority:
211 281
212 Event->io (fd => IO::AIO::poll_fileno, 282 Event->io (fd => IO::AIO::poll_fileno,
213 poll => 'r', async => 1, 283 poll => 'r', async => 1,
214 cb => \&IO::AIO::poll_cb); 284 cb => \&IO::AIO::poll_cb);
215 285
216=item IO::AIO::poll_wait 286=item IO::AIO::poll_wait
217 287
218Wait till the result filehandle becomes ready for reading (simply does a 288Wait till the result filehandle becomes ready for reading (simply does a
219select on the filehandle. This is useful if you want to synchronously wait 289C<select> on the filehandle. This is useful if you want to synchronously wait
220for some requests to finish). 290for some requests to finish).
221 291
222See C<nreqs> for an example. 292See C<nreqs> for an example.
223 293
224=item IO::AIO::nreqs 294=item IO::AIO::nreqs
225 295
226Returns the number of requests currently outstanding. 296Returns the number of requests currently outstanding (i.e. for which their
297callback has not been invoked yet).
227 298
228Example: wait till there are no outstanding requests anymore: 299Example: wait till there are no outstanding requests anymore:
229 300
230 IO::AIO::poll_wait, IO::AIO::poll_cb 301 IO::AIO::poll_wait, IO::AIO::poll_cb
231 while IO::AIO::nreqs; 302 while IO::AIO::nreqs;
232 303
304=item IO::AIO::flush
305
306Wait till all outstanding AIO requests have been handled.
307
308Strictly equivalent to:
309
310 IO::AIO::poll_wait, IO::AIO::poll_cb
311 while IO::AIO::nreqs;
312
313=item IO::AIO::poll
314
315Waits until some requests have been handled.
316
317Strictly equivalent to:
318
319 IO::AIO::poll_wait, IO::AIO::poll_cb
320 if IO::AIO::nreqs;
321
233=item IO::AIO::min_parallel $nthreads 322=item IO::AIO::min_parallel $nthreads
234 323
235Set the minimum number of AIO threads to C<$nthreads>. The default is 324Set the minimum number of AIO threads to C<$nthreads>. The current default
236C<1>, which means a single asynchronous operation can be done at one time 325is C<4>, which means four asynchronous operations can be done at one time
237(the number of outstanding operations, however, is unlimited). 326(the number of outstanding operations, however, is unlimited).
327
328IO::AIO starts threads only on demand, when an AIO request is queued and
329no free thread exists.
238 330
239It is recommended to keep the number of threads low, as some Linux 331It is recommended to keep the number of threads low, as some Linux
240kernel versions will scale negatively with the number of threads (higher 332kernel versions will scale negatively with the number of threads (higher
241parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 333parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
242threads should be fine. 334threads should be fine.
243 335
244Under normal circumstances you don't need to call this function, as this 336Under most circumstances you don't need to call this function, as the
245module automatically starts some threads (the exact number might change, 337module selects a default that is suitable for low to moderate load.
246and is currently 4).
247 338
248=item IO::AIO::max_parallel $nthreads 339=item IO::AIO::max_parallel $nthreads
249 340
250Sets the maximum number of AIO threads to C<$nthreads>. If more than 341Sets the maximum number of AIO threads to C<$nthreads>. If more than the
251the specified number of threads are currently running, kill them. This 342specified number of threads are currently running, this function kills
252function blocks until the limit is reached. 343them. This function blocks until the limit is reached.
344
345While C<$nthreads> are zero, aio requests get queued but not executed
346until the number of threads has been increased again.
253 347
254This module automatically runs C<max_parallel 0> at program end, to ensure 348This module automatically runs C<max_parallel 0> at program end, to ensure
255that all threads are killed and that there are no outstanding requests. 349that all threads are killed and that there are no outstanding requests.
256 350
257Under normal circumstances you don't need to call this function. 351Under normal circumstances you don't need to call this function.
… …
261Sets the maximum number of outstanding requests to C<$nreqs>. If you 355Sets the maximum number of outstanding requests to C<$nreqs>. If you
262try to queue up more than this number of requests, the caller will block until 356try to queue up more than this number of requests, the caller will block until
263some requests have been handled. 357some requests have been handled.
264 358
265The default is very large, so normally there is no practical limit. If you 359The default is very large, so normally there is no practical limit. If you
266queue up many requests in a loop it it often improves speed if you set 360queue up many requests in a loop it often improves speed if you set
267this to a relatively low number, such as C<100>. 361this to a relatively low number, such as C<100>.
268 362
269Under normal circumstances you don't need to call this function. 363Under normal circumstances you don't need to call this function.
270 364
271=back 365=back
… …
274 368
275# support function to convert a fd into a perl filehandle 369# support function to convert a fd into a perl filehandle
276sub _fd2fh { 370sub _fd2fh {
277 return undef if $_[0] < 0; 371 return undef if $_[0] < 0;
278 372
279 # try to be perl5.6-compatible 373 # try to generate nice filehandles
280 local *AIO_FH; 374 my $sym = "IO::AIO::fd#$_[0]";
281 open AIO_FH, "+<&=$_[0]" 375 local *$sym;
376
377 open *$sym, "+<&=$_[0]" # usually works under any unix
378 or open *$sym, "<&=$_[0]" # cygwin needs this
379 or open *$sym, ">&=$_[0]" # or this
282 or return undef; 380 or return undef;
283 381
284 *AIO_FH 382 *$sym
285} 383}
286 384
287min_parallel 4; 385min_parallel 4;
288 386
289END { 387END {
290 max_parallel 0; 388 max_parallel 0;
291} 389}
292 390
2931; 3911;
294 392
393=head2 FORK BEHAVIOUR
394
395Before the fork, IO::AIO enters a quiescent state where no requests
396can be added in other threads and no results will be processed. After
397the fork the parent simply leaves the quiescent state and continues
398request/result processing, while the child clears the request/result
399queue (so the requests started before the fork will only be handled in
400the parent). Threats will be started on demand until the limit ste in the
401parent process has been reached again.
402
295=head1 SEE ALSO 403=head1 SEE ALSO
296 404
297L<Coro>, L<Linux::AIO>. 405L<Coro>, L<Linux::AIO>.
298 406
299=head1 AUTHOR 407=head1 AUTHOR

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