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Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.24 by root, Wed Jun 29 15:28:14 2005 UTC vs.
Revision 1.33 by root, Sun Jul 10 16:33:04 2005 UTC

… …
6 6
7 use Linux::AIO; 7 use Linux::AIO;
8 8
9=head1 DESCRIPTION 9=head1 DESCRIPTION
10 10
11This module implements asynchronous i/o using the means available to linux 11This module implements asynchronous I/O using the means available to Linux
12- clone. It does not hook into the POSIX aio_* functions because linux 12- clone. It does not hook into the POSIX aio_* functions because Linux
13does not yet support these in the kernel (and even if, it would only allow 13does not yet support these in the kernel (even as of 2.6.12, only O_DIRECT
14aio_read and write, not open and stat). 14files are supported) and even if, it would only allow aio_read and write,
15not open, stat and so on.
15 16
16Instead, in this module a number of (non-posix) threads are started that 17Instead, in this module a number of (non-posix) threads are started that
17execute your read/writes and signal their completion. You don't need 18execute your read/writes and signal their completion. You don't need
18thread support in your libc or perl, and the threads created by this 19thread support in your libc or perl, and the threads created by this
19module will not be visible to the pthreads library. 20module will not be visible to the pthreads library.
20 21
21NOTICE: the threads created by this module will automatically be killed 22NOTICE: the threads created by this module will automatically be killed
22when the thread calling min_parallel exits. Make sure you only ever call 23when the thread calling min_parallel exits. Make sure you only ever call
23min_parallel from the same thread that loaded this module. 24min_parallel from the same thread that loaded this module.
24 25
25Although the module will work with threads, it is not reentrant, so use 26Although the module will work with in the presence of other threads, it is
26appropriate locking yourself. 27not reentrant, so use appropriate locking yourself.
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
41The filenames you pass to these routines I<must> be absolute. The reason
42is that at the time the request is being executed, the current working
43directory could have changed. Alternatively, you can make sure that you
44never change the current working directory.
27 45
28=over 4 46=over 4
29 47
30=cut 48=cut
31 49
32package Linux::AIO; 50package Linux::AIO;
33 51
34use base 'Exporter'; 52use base 'Exporter';
35 53
36BEGIN { 54BEGIN {
37 $VERSION = 1.5; 55 $VERSION = 1.71;
38 56
39 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink); 57 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
58 aio_fsync aio_fdatasync aio_readahead);
40 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs); 59 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);
41 60
42 require XSLoader; 61 require XSLoader;
43 XSLoader::load Linux::AIO, $VERSION; 62 XSLoader::load Linux::AIO, $VERSION;
44} 63}
… …
51 70
52It is recommended to keep the number of threads low, as some linux 71It is recommended to keep the number of threads low, as some linux
53kernel versions will scale negatively with the number of threads (higher 72kernel versions will scale negatively with the number of threads (higher
54parallelity => MUCH higher latency). 73parallelity => MUCH higher latency).
55 74
75Under normal circumstances you don't need to call this function, as this
76module automatically starts a single async thread.
77
56=item Linux::AIO::max_parallel $nthreads 78=item Linux::AIO::max_parallel $nthreads
57 79
58Sets the maximum number of AIO threads to C<$nthreads>. If more than 80Sets the maximum number of AIO threads to C<$nthreads>. If more than
59the specified number of threads are currently running, kill them. This 81the specified number of threads are currently running, kill them. This
60function blocks until the limit is reached. 82function blocks until the limit is reached.
61 83
62This module automatically runs C<max_parallel 0> at program end, to ensure 84This module automatically runs C<max_parallel 0> at program end, to ensure
63that all threads are killed and that there are no outstanding requests. 85that all threads are killed and that there are no outstanding requests.
86
87Under normal circumstances you don't need to call this function.
64 88
65=item $fileno = Linux::AIO::poll_fileno 89=item $fileno = Linux::AIO::poll_fileno
66 90
67Return the I<request result pipe filehandle>. This filehandle must be 91Return the I<request result pipe filehandle>. This filehandle must be
68polled for reading by some mechanism outside this module (e.g. Event 92polled for reading by some mechanism outside this module (e.g. Event
69or select, see below). If the pipe becomes readable you have to call 93or select, see below). If the pipe becomes readable you have to call
70C<poll_cb> to check the results. 94C<poll_cb> to check the results.
71 95
96See C<poll_cb> for an example.
97
72=item Linux::AIO::poll_cb 98=item Linux::AIO::poll_cb
73 99
74Process all outstanding events on the result pipe. You have to call this 100Process all outstanding events on the result pipe. You have to call this
75regularly. Returns the number of events processed. Returns immediately 101regularly. Returns the number of events processed. Returns immediately
76when no events are outstanding. 102when no events are outstanding.
77 103
78You can use Event to multiplex, e.g.: 104You can use Event to multiplex, e.g.:
79 105
80 Event->io (fd => Linux::AIO::poll_fileno, 106 Event->io (fd => Linux::AIO::poll_fileno,
81 poll => 'r', async => 1, 107 poll => 'r', async => 1,
82 cb => \&Linux::AIO::poll_cb ); 108 cb => \&Linux::AIO::poll_cb);
83 109
84=item Linux::AIO::poll_wait 110=item Linux::AIO::poll_wait
85 111
86Wait till the result filehandle becomes ready for reading (simply does a 112Wait till the result filehandle becomes ready for reading (simply does a
87select on the filehandle. This is useful if you want to synchronously wait 113select on the filehandle. This is useful if you want to synchronously wait
88for some requests to finish). 114for some requests to finish).
89 115
116See C<nreqs> for an example.
117
90=item Linux::AIO::nreqs 118=item Linux::AIO::nreqs
91 119
92Returns the number of requests currently outstanding. 120Returns the number of requests currently outstanding.
93 121
122Example: wait till there are no outstanding requests anymore:
123
124 Linux::AIO::poll_wait, Linux::AIO::poll_cb
125 while Linux::AIO::nreqs;
126
94=item aio_open $pathname, $flags, $mode, $callback 127=item aio_open $pathname, $flags, $mode, $callback
95 128
96Asynchronously open or create a file and call the callback with the 129Asynchronously open or create a file and call the callback with the
97filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this 130filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this
98might change in the future). 131might change in the future).
99 132
133The C<$mode> argument is a bitmask. See the C<Fcntl> module for a
134list. They are the same as used in C<sysopen>.
135
136Example:
137
138 aio_open "/etc/passwd", O_RDONLY, 0, sub {
139 if ($_[0] >= 0) {
140 open my $fh, "<&$_[0]"; # create a copy for perl
141 aio_close $_[0], sub { }; # close the aio handle
142 print "open successful, fh is $fh\n";
143 ...
144 } else {
145 die "open failed: $!\n";
146 }
147 };
148
100=item aio_close $fh, $callback 149=item aio_close $fh, $callback
101 150
102Asynchronously close a file and call the callback with the result code. 151Asynchronously close a file and call the callback with the result code.
103 152
104=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 153=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
105 154
106=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 155=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
107 156
108Reads or writes C<length> bytes from the specified C<fh> and C<offset> 157Reads or writes C<length> bytes from the specified C<fh> and C<offset>
109into the scalar given by C<data> and offset C<dataoffset> and calls the 158into the scalar given by C<data> and offset C<dataoffset> and calls the
110callback without the actual number of bytes read (or C<undef> on error). 159callback without the actual number of bytes read (or -1 on error, just
160like the syscall).
161
162Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at
163offset C<0> within the scalar:
164
165 aio_read $fh, 7, 15, $buffer, 0, sub {
166 $_[0] >= 0 or die "read error: $!";
167 print "read <$buffer>\n";
168 };
169
170=item aio_readahead $fh,$offset,$length, $callback
171
172Asynchronously reads the specified byte range into the page cache, using
173the C<readahead> syscall.
174
175readahead() populates the page cache with data from a file so that
176subsequent reads from that file will not block on disk I/O. The C<$offset>
177argument specifies the starting point from which data is to be read and
178C<$length> specifies the number of bytes to be read. I/O is performed in
179whole pages, so that offset is effectively rounded down to a page boundary
180and bytes are read up to the next page boundary greater than or equal to
181(off-set+length). aio_readahead() does not read beyond the end of the
182file. The current file offset of the file is left unchanged.
111 183
112=item aio_stat $fh_or_path, $callback 184=item aio_stat $fh_or_path, $callback
113 185
114=item aio_lstat $fh, $callback 186=item aio_lstat $fh, $callback
115 187
116Works like perl's C<stat> or C<lstat> in void context. The callback will 188Works like perl's C<stat> or C<lstat> in void context. The callback will
117be called after the stat and the results will be available using C<stat _> 189be called after the stat and the results will be available using C<stat _>
118or C<-s _> etc... 190or C<-s _> etc...
119 191
192The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
193for an explanation.
194
120Currently, the stats are always 64-bit-stats, i.e. instead of returning an 195Currently, the stats are always 64-bit-stats, i.e. instead of returning an
121error when stat'ing a large file, the results will be silently truncated 196error when stat'ing a large file, the results will be silently truncated
122unless perl itself is compiled with large file support. 197unless perl itself is compiled with large file support.
123 198
199Example: Print the length of F</etc/passwd>:
200
201 aio_stat "/etc/passwd", sub {
202 $_[0] and die "stat failed: $!";
203 print "size is ", -s _, "\n";
204 };
205
124=item aio_unlink $pathname, $callback 206=item aio_unlink $pathname, $callback
125 207
126Asynchronously unlink a file. 208Asynchronously unlink (delete) a file and call the callback with the
209result code.
210
211=item aio_fsync $fh, $callback
212
213Asynchronously call fsync on the given filehandle and call the callback
214with the fsync result code.
215
216=item aio_fdatasync $fh, $callback
217
218Asynchronously call fdatasync on the given filehandle and call the
219callback with the fdatasync result code.
127 220
128=cut 221=cut
129 222
130min_parallel 1; 223min_parallel 1;
131 224

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