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Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.29 by root, Sat Jul 9 22:45:05 2005 UTC vs.
Revision 1.30 by root, Sat Jul 9 23:30:00 2005 UTC

… …
24min_parallel from the same thread that loaded this module. 24min_parallel from the same thread that loaded this module.
25 25
26Although the module will work with in the presence of other threads, it is 26Although the module will work with in the presence of other threads, it is
27not reentrant, so use appropriate locking yourself. 27not reentrant, so use appropriate locking yourself.
28 28
29=head2 API NOTES
30
31All the C<aio_*> calls are more or less thin wrappers around the syscall
32with the same name (sans C<aio_>). The arguments are similar or identical,
33and they all accept an additional C<$callback> argument which must be
34a code reference. This code reference will get called with the syscall
35return code (e.g. most syscalls return C<-1> on error, unlike perl, which
36usually delivers "false") as it's sole argument when the given syscall has
37been executed asynchronously.
38
39All functions that expect a filehandle will also accept a file descriptor.
40
29=over 4 41=over 4
30 42
31=cut 43=cut
32 44
33package Linux::AIO; 45package Linux::AIO;
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53 65
54It is recommended to keep the number of threads low, as some linux 66It is recommended to keep the number of threads low, as some linux
55kernel versions will scale negatively with the number of threads (higher 67kernel versions will scale negatively with the number of threads (higher
56parallelity => MUCH higher latency). 68parallelity => MUCH higher latency).
57 69
70Under normal circumstances you don't need to call this function, as this
71module automatically starts a single async thread.
72
58=item Linux::AIO::max_parallel $nthreads 73=item Linux::AIO::max_parallel $nthreads
59 74
60Sets the maximum number of AIO threads to C<$nthreads>. If more than 75Sets the maximum number of AIO threads to C<$nthreads>. If more than
61the specified number of threads are currently running, kill them. This 76the specified number of threads are currently running, kill them. This
62function blocks until the limit is reached. 77function blocks until the limit is reached.
63 78
64This module automatically runs C<max_parallel 0> at program end, to ensure 79This module automatically runs C<max_parallel 0> at program end, to ensure
65that all threads are killed and that there are no outstanding requests. 80that all threads are killed and that there are no outstanding requests.
81
82Under normal circumstances you don't need to call this function.
66 83
67=item $fileno = Linux::AIO::poll_fileno 84=item $fileno = Linux::AIO::poll_fileno
68 85
69Return the I<request result pipe filehandle>. This filehandle must be 86Return the I<request result pipe filehandle>. This filehandle must be
70polled for reading by some mechanism outside this module (e.g. Event 87polled for reading by some mechanism outside this module (e.g. Event
71or select, see below). If the pipe becomes readable you have to call 88or select, see below). If the pipe becomes readable you have to call
72C<poll_cb> to check the results. 89C<poll_cb> to check the results.
73 90
91See C<poll_cb> for an example.
92
74=item Linux::AIO::poll_cb 93=item Linux::AIO::poll_cb
75 94
76Process all outstanding events on the result pipe. You have to call this 95Process all outstanding events on the result pipe. You have to call this
77regularly. Returns the number of events processed. Returns immediately 96regularly. Returns the number of events processed. Returns immediately
78when no events are outstanding. 97when no events are outstanding.
79 98
80You can use Event to multiplex, e.g.: 99You can use Event to multiplex, e.g.:
81 100
82 Event->io (fd => Linux::AIO::poll_fileno, 101 Event->io (fd => Linux::AIO::poll_fileno,
83 poll => 'r', async => 1, 102 poll => 'r', async => 1,
84 cb => \&Linux::AIO::poll_cb ); 103 cb => \&Linux::AIO::poll_cb);
85 104
86=item Linux::AIO::poll_wait 105=item Linux::AIO::poll_wait
87 106
88Wait till the result filehandle becomes ready for reading (simply does a 107Wait till the result filehandle becomes ready for reading (simply does a
89select on the filehandle. This is useful if you want to synchronously wait 108select on the filehandle. This is useful if you want to synchronously wait
90for some requests to finish). 109for some requests to finish).
91 110
111See C<nreqs> for an example.
112
92=item Linux::AIO::nreqs 113=item Linux::AIO::nreqs
93 114
94Returns the number of requests currently outstanding. 115Returns the number of requests currently outstanding.
95 116
117Example: wait till there are no outstanding requests anymore:
118
119 Linux::AIO::poll_wait while Linux::AIO::nreqs;
120
96=item aio_open $pathname, $flags, $mode, $callback 121=item aio_open $pathname, $flags, $mode, $callback
97 122
98Asynchronously open or create a file and call the callback with the 123Asynchronously open or create a file and call the callback with the
99filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this 124filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this
100might change in the future). 125might change in the future).
101 126
127The C<$mode> argument is a bitmask. See the C<Fcntl> module for a
128list. They are the same as used in C<sysopen>.
129
130Example:
131
132 aio_open "/etc/passwd", O_RDONLY, 0, sub {
133 if ($_[0] >= 0) {
134 open my $fh, "<&$_[0]"; # create a copy for perl
135 aio_close $_[0], sub { }; # close the aio handle
136 print "open successful, fh is $fh\n";
137 ...
138 } else {
139 die "open failed: $!\n";
140 }
141 };
142
102=item aio_close $fh, $callback 143=item aio_close $fh, $callback
103 144
104Asynchronously close a file and call the callback with the result code. 145Asynchronously close a file and call the callback with the result code.
105 146
106=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 147=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
107 148
108=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 149=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
109 150
110Reads or writes C<length> bytes from the specified C<fh> and C<offset> 151Reads or writes C<length> bytes from the specified C<fh> and C<offset>
111into the scalar given by C<data> and offset C<dataoffset> and calls the 152into the scalar given by C<data> and offset C<dataoffset> and calls the
112callback without the actual number of bytes read (or C<undef> on error). 153callback without the actual number of bytes read (or -1 on error, just
154like the syscall).
155
156Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at
157offset C<0> within the scalar:
158
159 aio_read $fh, 7, 15, $buffer, 0, sub {
160 $_[0] >= 0 or die "read error: $!";
161 print "read <$buffer>\n";
162 };
163
164=item aio_readahead $fh,$offset,$length, $callback
165
166Asynchronously reads the specified byte range into the page cache, using
167the C<readahead> syscall.
168
169readahead() populates the page cache with data from a file so that
170subsequent reads from that file will not block on disk I/O. The C<$offset>
171argument specifies the starting point from which data is to be read and
172C<$length> specifies the number of bytes to be read. I/O is performed in
173whole pages, so that offset is effectively rounded down to a page boundary
174and bytes are read up to the next page boundary greater than or equal to
175(off-set+length). aio_readahead() does not read beyond the end of the
176file. The current file offset of the file is left unchanged.
113 177
114=item aio_stat $fh_or_path, $callback 178=item aio_stat $fh_or_path, $callback
115 179
116=item aio_lstat $fh, $callback 180=item aio_lstat $fh, $callback
117 181
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121 185
122Currently, the stats are always 64-bit-stats, i.e. instead of returning an 186Currently, the stats are always 64-bit-stats, i.e. instead of returning an
123error when stat'ing a large file, the results will be silently truncated 187error when stat'ing a large file, the results will be silently truncated
124unless perl itself is compiled with large file support. 188unless perl itself is compiled with large file support.
125 189
190Example: Print the length of F</etc/passwd>:
191
192 aio_stat "/etc/passwd", sub {
193 $_[0] and die "stat failed: $!";
194 print "size is ", -s _, "\n";
195 };
196
126=item aio_unlink $pathname, $callback 197=item aio_unlink $pathname, $callback
127 198
128Asynchronously unlink a file. 199Asynchronously unlink (delete) a file and call the callback with the
200result code.
201
202=item aio_fsync $fh, $callback
203
204Asynchronously call fsync on the given filehandle and call the callback
205with the fsync result code.
206
207=item aio_fdatasync $fh, $callback
208
209Asynchronously call fdatasync on the given filehandle and call the
210callback with the fdatasync result code.
129 211
130=cut 212=cut
131 213
132min_parallel 1; 214min_parallel 1;
133 215

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