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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_sendfile aio_read aio_write aio_open aio_close aio_stat
71 aio_lstat aio_unlink aio_rmdir aio_readdir aio_symlink
62 aio_fsync aio_fdatasync aio_readahead); 72 aio_fsync aio_fdatasync aio_readahead);
63 @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
74 max_outstanding nreqs);
64 75
65 require XSLoader; 76 require XSLoader;
66 XSLoader::load IO::AIO, $VERSION; 77 XSLoader::load IO::AIO, $VERSION;
67} 78}
68 79
… …
70 81
71=head2 AIO FUNCTIONS 82=head2 AIO FUNCTIONS
72 83
73All the C<aio_*> calls are more or less thin wrappers around the syscall 84All the C<aio_*> calls are more or less thin wrappers around the syscall
74with the same name (sans C<aio_>). The arguments are similar or identical, 85with the same name (sans C<aio_>). The arguments are similar or identical,
75and they all accept an additional C<$callback> argument which must be 86and they all accept an additional (and optional) C<$callback> argument
76a code reference. This code reference will get called with the syscall 87which 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 88the 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 89perl, which usually delivers "false") as it's sole argument when the given
79been executed asynchronously. 90syscall has been executed asynchronously.
80 91
81All functions that expect a filehandle will also accept a file descriptor. 92All functions expecting a filehandle keep a copy of the filehandle
93internally until the request has finished.
82 94
83The filenames you pass to these routines I<must> be absolute. The reason 95The pathnames you pass to these routines I<must> be absolute and
84is that at the time the request is being executed, the current working 96encoded 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 97request is being executed, the current working directory could have
98changed. Alternatively, you can make sure that you never change the
86never change the current working directory. 99current working directory.
100
101To encode pathnames to byte form, either make sure you either: a)
102always pass in filenames you got from outside (command line, readdir
103etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
104your pathnames to the locale (or other) encoding in effect in the user
105environment, d) use Glib::filename_from_unicode on unicode filenames or e)
106use something else.
87 107
88=over 4 108=over 4
89 109
90=item aio_open $pathname, $flags, $mode, $callback 110=item aio_open $pathname, $flags, $mode, $callback
91 111
… …
93created filehandle for the file. 113created filehandle for the file.
94 114
95The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 115The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
96for an explanation. 116for an explanation.
97 117
98The C<$mode> argument is a bitmask. See the C<Fcntl> module for a 118The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
99list. They are the same as used in C<sysopen>. 119list. They are the same as used by C<sysopen>.
120
121Likewise, C<$mode> specifies the mode of the newly created file, if it
122didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
123except that it is mandatory (i.e. use C<0> if you don't create new files,
124and C<0666> or C<0777> if you do).
100 125
101Example: 126Example:
102 127
103 aio_open "/etc/passwd", O_RDONLY, 0, sub { 128 aio_open "/etc/passwd", O_RDONLY, 0, sub {
104 if ($_[0]) { 129 if ($_[0]) {
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111 136
112=item aio_close $fh, $callback 137=item aio_close $fh, $callback
113 138
114Asynchronously close a file and call the callback with the result 139Asynchronously close a file and call the callback with the result
115code. I<WARNING:> although accepted, you should not pass in a perl 140code. I<WARNING:> although accepted, you should not pass in a perl
116filehandle here, as perl will likely close the file descriptor itself when 141filehandle here, as perl will likely close the file descriptor another
117the filehandle is destroyed. Normally, you can safely call perls C<close> 142time when the filehandle is destroyed. Normally, you can safely call perls
118or just let filehandles go out of scope. 143C<close> or just let filehandles go out of scope.
144
145This is supposed to be a bug in the API, so that might change. It's
146therefore best to avoid this function.
119 147
120=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 148=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
121 149
122=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 150=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
123 151
124Reads or writes C<length> bytes from the specified C<fh> and C<offset> 152Reads or writes C<length> bytes from the specified C<fh> and C<offset>
125into the scalar given by C<data> and offset C<dataoffset> and calls the 153into the scalar given by C<data> and offset C<dataoffset> and calls the
126callback without the actual number of bytes read (or -1 on error, just 154callback without the actual number of bytes read (or -1 on error, just
127like the syscall). 155like the syscall).
128 156
157The C<$data> scalar I<MUST NOT> be modified in any way while the request
158is outstanding. Modifying it can result in segfaults or WW3 (if the
159necessary/optional hardware is installed).
160
129Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at 161Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
130offset C<0> within the scalar: 162offset C<0> within the scalar:
131 163
132 aio_read $fh, 7, 15, $buffer, 0, sub { 164 aio_read $fh, 7, 15, $buffer, 0, sub {
133 $_[0] >= 0 or die "read error: $!"; 165 $_[0] > 0 or die "read error: $!";
134 print "read <$buffer>\n"; 166 print "read $_[0] bytes: <$buffer>\n";
135 }; 167 };
136 168
169=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback
170
171Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
172reading at byte offset C<$in_offset>, and starts writing at the current
173file offset of C<$out_fh>. Because of that, it is not safe to issue more
174than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
175other.
176
177This call tries to make use of a native C<sendfile> syscall to provide
178zero-copy operation. For this to work, C<$out_fh> should refer to a
179socket, and C<$in_fh> should refer to mmap'able file.
180
181If the native sendfile call fails or is not implemented, it will be
182emulated, so you can call C<aio_sendfile> on any type of filehandle
183regardless of the limitations of the operating system.
184
185Please note, however, that C<aio_sendfile> can read more bytes from
186C<$in_fh> than are written, and there is no way to find out how many
187bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
188provides the number of bytes written to C<$out_fh>. Only if the result
189value equals C<$length> one can assume that C<$length> bytes have been
190read.
191
137=item aio_readahead $fh,$offset,$length, $callback 192=item aio_readahead $fh,$offset,$length, $callback
138 193
139Asynchronously reads the specified byte range into the page cache, using
140the C<readahead> syscall. If that syscall doesn't exist the status will be
141C<-1> and C<$!> is set to ENOSYS.
142
143readahead() populates the page cache with data from a file so that 194C<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<$offset> 195subsequent reads from that file will not block on disk I/O. The C<$offset>
145argument specifies the starting point from which data is to be read and 196argument specifies the starting point from which data is to be read and
146C<$length> specifies the number of bytes to be read. I/O is performed in 197C<$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 198whole 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 199and 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 200(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. 201file. The current file offset of the file is left unchanged.
202
203If that syscall doesn't exist (likely if your OS isn't Linux) it will be
204emulated by simply reading the data, which would have a similar effect.
151 205
152=item aio_stat $fh_or_path, $callback 206=item aio_stat $fh_or_path, $callback
153 207
154=item aio_lstat $fh, $callback 208=item aio_lstat $fh, $callback
155 209
… …
174=item aio_unlink $pathname, $callback 228=item aio_unlink $pathname, $callback
175 229
176Asynchronously unlink (delete) a file and call the callback with the 230Asynchronously unlink (delete) a file and call the callback with the
177result code. 231result code.
178 232
233=item aio_rmdir $pathname, $callback
234
235Asynchronously rmdir (delete) a directory and call the callback with the
236result code.
237
238=item aio_readdir $pathname $callback
239
240Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
241directory (i.e. opendir + readdir + closedir). The entries will not be
242sorted, and will B<NOT> include the C<.> and C<..> entries.
243
244The callback a single argument which is either C<undef> or an array-ref
245with the filenames.
246
179=item aio_fsync $fh, $callback 247=item aio_fsync $fh, $callback
180 248
181Asynchronously call fsync on the given filehandle and call the callback 249Asynchronously call fsync on the given filehandle and call the callback
182with the fsync result code. 250with the fsync result code.
183 251
184=item aio_fdatasync $fh, $callback 252=item aio_fdatasync $fh, $callback
185 253
186Asynchronously call fdatasync on the given filehandle and call the 254Asynchronously call fdatasync on the given filehandle and call the
187callback with the fdatasync result code. 255callback with the fdatasync result code.
188 256
257If this call isn't available because your OS lacks it or it couldn't be
258detected, it will be emulated by calling C<fsync> instead.
259
189=back 260=back
190 261
191=head2 SUPPORT FUNCTIONS 262=head2 SUPPORT FUNCTIONS
192 263
193=over 4 264=over 4
194 265
195=item $fileno = IO::AIO::poll_fileno 266=item $fileno = IO::AIO::poll_fileno
196 267
197Return the I<request result pipe filehandle>. This filehandle must be 268Return the I<request result pipe file descriptor>. This filehandle must be
198polled for reading by some mechanism outside this module (e.g. Event 269polled 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 270select, see below or the SYNOPSIS). If the pipe becomes readable you have
200C<poll_cb> to check the results. 271to call C<poll_cb> to check the results.
201 272
202See C<poll_cb> for an example. 273See C<poll_cb> for an example.
203 274
204=item IO::AIO::poll_cb 275=item IO::AIO::poll_cb
205 276
206Process all outstanding events on the result pipe. You have to call this 277Process all outstanding events on the result pipe. You have to call this
207regularly. Returns the number of events processed. Returns immediately 278regularly. Returns the number of events processed. Returns immediately
208when no events are outstanding. 279when no events are outstanding.
209 280
210You can use Event to multiplex, e.g.: 281Example: Install an Event watcher that automatically calls
282IO::AIO::poll_cb with high priority:
211 283
212 Event->io (fd => IO::AIO::poll_fileno, 284 Event->io (fd => IO::AIO::poll_fileno,
213 poll => 'r', async => 1, 285 poll => 'r', async => 1,
214 cb => \&IO::AIO::poll_cb); 286 cb => \&IO::AIO::poll_cb);
215 287
216=item IO::AIO::poll_wait 288=item IO::AIO::poll_wait
217 289
218Wait till the result filehandle becomes ready for reading (simply does a 290Wait till the result filehandle becomes ready for reading (simply does a
219select on the filehandle. This is useful if you want to synchronously wait 291C<select> on the filehandle. This is useful if you want to synchronously wait
220for some requests to finish). 292for some requests to finish).
221 293
222See C<nreqs> for an example. 294See C<nreqs> for an example.
223 295
224=item IO::AIO::nreqs 296=item IO::AIO::nreqs
225 297
226Returns the number of requests currently outstanding. 298Returns the number of requests currently outstanding (i.e. for which their
299callback has not been invoked yet).
227 300
228Example: wait till there are no outstanding requests anymore: 301Example: wait till there are no outstanding requests anymore:
229 302
230 IO::AIO::poll_wait, IO::AIO::poll_cb 303 IO::AIO::poll_wait, IO::AIO::poll_cb
231 while IO::AIO::nreqs; 304 while IO::AIO::nreqs;
232 305
306=item IO::AIO::flush
307
308Wait till all outstanding AIO requests have been handled.
309
310Strictly equivalent to:
311
312 IO::AIO::poll_wait, IO::AIO::poll_cb
313 while IO::AIO::nreqs;
314
315=item IO::AIO::poll
316
317Waits until some requests have been handled.
318
319Strictly equivalent to:
320
321 IO::AIO::poll_wait, IO::AIO::poll_cb
322 if IO::AIO::nreqs;
323
233=item IO::AIO::min_parallel $nthreads 324=item IO::AIO::min_parallel $nthreads
234 325
235Set the minimum number of AIO threads to C<$nthreads>. The default is 326Set 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 327is C<4>, which means four asynchronous operations can be done at one time
237(the number of outstanding operations, however, is unlimited). 328(the number of outstanding operations, however, is unlimited).
329
330IO::AIO starts threads only on demand, when an AIO request is queued and
331no free thread exists.
238 332
239It is recommended to keep the number of threads low, as some Linux 333It is recommended to keep the number of threads low, as some Linux
240kernel versions will scale negatively with the number of threads (higher 334kernel versions will scale negatively with the number of threads (higher
241parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 335parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
242threads should be fine. 336threads should be fine.
243 337
244Under normal circumstances you don't need to call this function, as this 338Under most circumstances you don't need to call this function, as the
245module automatically starts some threads (the exact number might change, 339module selects a default that is suitable for low to moderate load.
246and is currently 4).
247 340
248=item IO::AIO::max_parallel $nthreads 341=item IO::AIO::max_parallel $nthreads
249 342
250Sets the maximum number of AIO threads to C<$nthreads>. If more than 343Sets the maximum number of AIO threads to C<$nthreads>. If more than the
251the specified number of threads are currently running, kill them. This 344specified number of threads are currently running, this function kills
252function blocks until the limit is reached. 345them. This function blocks until the limit is reached.
346
347While C<$nthreads> are zero, aio requests get queued but not executed
348until the number of threads has been increased again.
253 349
254This module automatically runs C<max_parallel 0> at program end, to ensure 350This module automatically runs C<max_parallel 0> at program end, to ensure
255that all threads are killed and that there are no outstanding requests. 351that all threads are killed and that there are no outstanding requests.
256 352
257Under normal circumstances you don't need to call this function. 353Under normal circumstances you don't need to call this function.
… …
261Sets the maximum number of outstanding requests to C<$nreqs>. If you 357Sets the maximum number of outstanding requests to C<$nreqs>. If you
262try to queue up more than this number of requests, the caller will block until 358try to queue up more than this number of requests, the caller will block until
263some requests have been handled. 359some requests have been handled.
264 360
265The default is very large, so normally there is no practical limit. If you 361The 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 362queue up many requests in a loop it often improves speed if you set
267this to a relatively low number, such as C<100>. 363this to a relatively low number, such as C<100>.
268 364
269Under normal circumstances you don't need to call this function. 365Under normal circumstances you don't need to call this function.
270 366
271=back 367=back
… …
274 370
275# support function to convert a fd into a perl filehandle 371# support function to convert a fd into a perl filehandle
276sub _fd2fh { 372sub _fd2fh {
277 return undef if $_[0] < 0; 373 return undef if $_[0] < 0;
278 374
279 # try to be perl5.6-compatible 375 # try to generate nice filehandles
280 local *AIO_FH; 376 my $sym = "IO::AIO::fd#$_[0]";
281 open AIO_FH, "+<&=$_[0]" 377 local *$sym;
378
379 open *$sym, "+<&=$_[0]" # usually works under any unix
380 or open *$sym, "<&=$_[0]" # cygwin needs this
381 or open *$sym, ">&=$_[0]" # or this
282 or return undef; 382 or return undef;
283 383
284 *AIO_FH 384 *$sym
285} 385}
286 386
287min_parallel 4; 387min_parallel 4;
288 388
289END { 389END {
290 max_parallel 0; 390 max_parallel 0;
291} 391}
292 392
2931; 3931;
294 394
395=head2 FORK BEHAVIOUR
396
397Before the fork, IO::AIO enters a quiescent state where no requests
398can be added in other threads and no results will be processed. After
399the fork the parent simply leaves the quiescent state and continues
400request/result processing, while the child clears the request/result
401queue (so the requests started before the fork will only be handled in
402the parent). Threats will be started on demand until the limit ste in the
403parent process has been reached again.
404
295=head1 SEE ALSO 405=head1 SEE ALSO
296 406
297L<Coro>, L<Linux::AIO>. 407L<Coro>, L<Linux::AIO>.
298 408
299=head1 AUTHOR 409=head1 AUTHOR

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