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3 | IO::AIO - Asynchronous Input/Output |
3 | IO::AIO - Asynchronous Input/Output |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use IO::AIO; |
7 | use IO::AIO; |
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8 | |
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9 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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10 | my ($fh) = @_; |
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11 | ... |
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12 | }; |
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13 | |
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14 | aio_unlink "/tmp/file", sub { }; |
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15 | |
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16 | aio_read $fh, 30000, 1024, $buffer, 0, sub { |
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17 | $_[0] > 0 or die "read error: $!"; |
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18 | }; |
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19 | |
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20 | # Event |
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21 | Event->io (fd => IO::AIO::poll_fileno, |
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22 | poll => 'r', |
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23 | cb => \&IO::AIO::poll_cb); |
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24 | |
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25 | # Glib/Gtk2 |
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26 | add_watch Glib::IO IO::AIO::poll_fileno, |
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27 | in => sub { IO::AIO::poll_cb, 1 }; |
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28 | |
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29 | # Tk |
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30 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
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31 | readable => \&IO::AIO::poll_cb); |
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32 | |
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33 | # Danga::Socket |
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34 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
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35 | \&IO::AIO::poll_cb); |
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36 | |
8 | |
37 | |
9 | =head1 DESCRIPTION |
38 | =head1 DESCRIPTION |
10 | |
39 | |
11 | This module implements asynchronous I/O using whatever means your |
40 | This module implements asynchronous I/O using whatever means your |
12 | operating system supports. |
41 | operating system supports. |
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30 | use base 'Exporter'; |
59 | use base 'Exporter'; |
31 | |
60 | |
32 | use Fcntl (); |
61 | use Fcntl (); |
33 | |
62 | |
34 | BEGIN { |
63 | BEGIN { |
35 | $VERSION = 0.2; |
64 | $VERSION = 0.5; |
36 | |
65 | |
37 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
66 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
38 | aio_fsync aio_fdatasync aio_readahead); |
67 | aio_fsync aio_fdatasync aio_readahead); |
39 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); |
68 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); |
40 | |
69 | |
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46 | |
75 | |
47 | =head2 AIO FUNCTIONS |
76 | =head2 AIO FUNCTIONS |
48 | |
77 | |
49 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
78 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
50 | with the same name (sans C<aio_>). The arguments are similar or identical, |
79 | with the same name (sans C<aio_>). The arguments are similar or identical, |
51 | and they all accept an additional C<$callback> argument which must be |
80 | and they all accept an additional (and optional) C<$callback> argument |
52 | a code reference. This code reference will get called with the syscall |
81 | which must be a code reference. This code reference will get called with |
53 | return code (e.g. most syscalls return C<-1> on error, unlike perl, which |
82 | the syscall return code (e.g. most syscalls return C<-1> on error, unlike |
54 | usually delivers "false") as it's sole argument when the given syscall has |
83 | perl, which usually delivers "false") as it's sole argument when the given |
55 | been executed asynchronously. |
84 | syscall has been executed asynchronously. |
56 | |
85 | |
57 | All functions that expect a filehandle will also accept a file descriptor. |
86 | All functions that expect a filehandle will also accept a file descriptor. |
58 | |
87 | |
59 | The filenames you pass to these routines I<must> be absolute. The reason |
88 | The filenames you pass to these routines I<must> be absolute. The reason |
60 | is that at the time the request is being executed, the current working |
89 | for this is that at the time the request is being executed, the current |
61 | directory could have changed. Alternatively, you can make sure that you |
90 | working directory could have changed. Alternatively, you can make sure |
62 | never change the current working directory. |
91 | that you never change the current working directory. |
63 | |
92 | |
64 | =over 4 |
93 | =over 4 |
65 | |
94 | |
66 | =item aio_open $pathname, $flags, $mode, $callback |
95 | =item aio_open $pathname, $flags, $mode, $callback |
67 | |
96 | |
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69 | created filehandle for the file. |
98 | created filehandle for the file. |
70 | |
99 | |
71 | The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
100 | The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
72 | for an explanation. |
101 | for an explanation. |
73 | |
102 | |
74 | The C<$mode> argument is a bitmask. See the C<Fcntl> module for a |
103 | The C<$flags> argument is a bitmask. See the C<Fcntl> module for a |
75 | list. They are the same as used in C<sysopen>. |
104 | list. They are the same as used by C<sysopen>. |
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105 | |
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106 | Likewise, C<$mode> specifies the mode of the newly created file, if it |
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107 | didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, |
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108 | except that it is mandatory (i.e. use C<0> if you don't create new files, |
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109 | and C<0666> or C<0777> if you do). |
76 | |
110 | |
77 | Example: |
111 | Example: |
78 | |
112 | |
79 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
113 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
80 | if ($_[0]) { |
114 | if ($_[0]) { |
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87 | |
121 | |
88 | =item aio_close $fh, $callback |
122 | =item aio_close $fh, $callback |
89 | |
123 | |
90 | Asynchronously close a file and call the callback with the result |
124 | Asynchronously close a file and call the callback with the result |
91 | code. I<WARNING:> although accepted, you should not pass in a perl |
125 | code. I<WARNING:> although accepted, you should not pass in a perl |
92 | filehandle here, as perl will likely close the file descriptor itself when |
126 | filehandle here, as perl will likely close the file descriptor another |
93 | the filehandle is destroyed. Normally, you can safely call perls C<close> |
127 | time when the filehandle is destroyed. Normally, you can safely call perls |
94 | or just let filehandles go out of scope. |
128 | C<close> or just let filehandles go out of scope. |
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129 | |
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130 | This is supposed to be a bug in the API, so that might change. It's |
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131 | therefore best to avoid this function. |
95 | |
132 | |
96 | =item aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
133 | =item aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
97 | |
134 | |
98 | =item aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
135 | =item aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
99 | |
136 | |
100 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
137 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
101 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
138 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
102 | callback without the actual number of bytes read (or -1 on error, just |
139 | callback without the actual number of bytes read (or -1 on error, just |
103 | like the syscall). |
140 | like the syscall). |
104 | |
141 | |
105 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at |
142 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
106 | offset C<0> within the scalar: |
143 | offset C<0> within the scalar: |
107 | |
144 | |
108 | aio_read $fh, 7, 15, $buffer, 0, sub { |
145 | aio_read $fh, 7, 15, $buffer, 0, sub { |
109 | $_[0] >= 0 or die "read error: $!"; |
146 | $_[0] > 0 or die "read error: $!"; |
110 | print "read <$buffer>\n"; |
147 | print "read $_[0] bytes: <$buffer>\n"; |
111 | }; |
148 | }; |
112 | |
149 | |
113 | =item aio_readahead $fh,$offset,$length, $callback |
150 | =item aio_readahead $fh,$offset,$length, $callback |
114 | |
151 | |
115 | Asynchronously reads the specified byte range into the page cache, using |
152 | Asynchronously reads the specified byte range into the page cache, using |
116 | the C<readahead> syscall. If that syscall doesn't exist the status will be |
153 | the C<readahead> syscall. If that syscall doesn't exist (likely if your OS |
117 | C<-1> and C<$!> is set to ENOSYS. |
154 | isn't Linux) the status will be C<-1> and C<$!> is set to C<ENOSYS>. |
118 | |
155 | |
119 | readahead() populates the page cache with data from a file so that |
156 | C<aio_readahead> populates the page cache with data from a file so that |
120 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
157 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
121 | argument specifies the starting point from which data is to be read and |
158 | argument specifies the starting point from which data is to be read and |
122 | C<$length> specifies the number of bytes to be read. I/O is performed in |
159 | C<$length> specifies the number of bytes to be read. I/O is performed in |
123 | whole pages, so that offset is effectively rounded down to a page boundary |
160 | whole pages, so that offset is effectively rounded down to a page boundary |
124 | and bytes are read up to the next page boundary greater than or equal to |
161 | and 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 |
162 | (off-set+length). C<aio_readahead> does not read beyond the end of the |
126 | file. The current file offset of the file is left unchanged. |
163 | file. The current file offset of the file is left unchanged. |
127 | |
164 | |
128 | =item aio_stat $fh_or_path, $callback |
165 | =item aio_stat $fh_or_path, $callback |
129 | |
166 | |
130 | =item aio_lstat $fh, $callback |
167 | =item aio_lstat $fh, $callback |
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158 | with the fsync result code. |
195 | with the fsync result code. |
159 | |
196 | |
160 | =item aio_fdatasync $fh, $callback |
197 | =item aio_fdatasync $fh, $callback |
161 | |
198 | |
162 | Asynchronously call fdatasync on the given filehandle and call the |
199 | Asynchronously call fdatasync on the given filehandle and call the |
163 | callback with the fdatasync result code. |
200 | callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if |
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201 | C<fdatasync> is not available. |
164 | |
202 | |
165 | =back |
203 | =back |
166 | |
204 | |
167 | =head2 SUPPORT FUNCTIONS |
205 | =head2 SUPPORT FUNCTIONS |
168 | |
206 | |
169 | =over 4 |
207 | =over 4 |
170 | |
208 | |
171 | =item $fileno = IO::AIO::poll_fileno |
209 | =item $fileno = IO::AIO::poll_fileno |
172 | |
210 | |
173 | Return the I<request result pipe filehandle>. This filehandle must be |
211 | Return the I<request result pipe file descriptor>. This filehandle must be |
174 | polled for reading by some mechanism outside this module (e.g. Event |
212 | polled for reading by some mechanism outside this module (e.g. Event or |
175 | or select, see below). If the pipe becomes readable you have to call |
213 | select, see below or the SYNOPSIS). If the pipe becomes readable you have |
176 | C<poll_cb> to check the results. |
214 | to call C<poll_cb> to check the results. |
177 | |
215 | |
178 | See C<poll_cb> for an example. |
216 | See C<poll_cb> for an example. |
179 | |
217 | |
180 | =item IO::AIO::poll_cb |
218 | =item IO::AIO::poll_cb |
181 | |
219 | |
182 | Process all outstanding events on the result pipe. You have to call this |
220 | Process all outstanding events on the result pipe. You have to call this |
183 | regularly. Returns the number of events processed. Returns immediately |
221 | regularly. Returns the number of events processed. Returns immediately |
184 | when no events are outstanding. |
222 | when no events are outstanding. |
185 | |
223 | |
186 | You can use Event to multiplex, e.g.: |
224 | Example: Install an Event watcher that automatically calls |
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225 | IO::AIO::poll_cb with high priority: |
187 | |
226 | |
188 | Event->io (fd => IO::AIO::poll_fileno, |
227 | Event->io (fd => IO::AIO::poll_fileno, |
189 | poll => 'r', async => 1, |
228 | poll => 'r', async => 1, |
190 | cb => \&IO::AIO::poll_cb); |
229 | cb => \&IO::AIO::poll_cb); |
191 | |
230 | |
192 | =item IO::AIO::poll_wait |
231 | =item IO::AIO::poll_wait |
193 | |
232 | |
194 | Wait till the result filehandle becomes ready for reading (simply does a |
233 | Wait till the result filehandle becomes ready for reading (simply does a |
195 | select on the filehandle. This is useful if you want to synchronously wait |
234 | C<select> on the filehandle. This is useful if you want to synchronously wait |
196 | for some requests to finish). |
235 | for some requests to finish). |
197 | |
236 | |
198 | See C<nreqs> for an example. |
237 | See C<nreqs> for an example. |
199 | |
238 | |
200 | =item IO::AIO::nreqs |
239 | =item IO::AIO::nreqs |
201 | |
240 | |
202 | Returns the number of requests currently outstanding. |
241 | Returns the number of requests currently outstanding (i.e. for which their |
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242 | callback has not been invoked yet). |
203 | |
243 | |
204 | Example: wait till there are no outstanding requests anymore: |
244 | Example: wait till there are no outstanding requests anymore: |
205 | |
245 | |
206 | IO::AIO::poll_wait, IO::AIO::poll_cb |
246 | IO::AIO::poll_wait, IO::AIO::poll_cb |
207 | while IO::AIO::nreqs; |
247 | while IO::AIO::nreqs; |
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248 | |
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249 | =item IO::AIO::flush |
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250 | |
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251 | Wait till all outstanding AIO requests have been handled. |
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252 | |
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253 | Strictly equivalent to: |
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254 | |
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255 | IO::AIO::poll_wait, IO::AIO::poll_cb |
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256 | while IO::AIO::nreqs; |
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257 | |
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258 | =item IO::AIO::poll |
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259 | |
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260 | Waits until some requests have been handled. |
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261 | |
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262 | Strictly equivalent to: |
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263 | |
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264 | IO::AIO::poll_wait, IO::AIO::poll_cb |
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265 | if IO::AIO::nreqs; |
208 | |
266 | |
209 | =item IO::AIO::min_parallel $nthreads |
267 | =item IO::AIO::min_parallel $nthreads |
210 | |
268 | |
211 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
269 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
212 | C<1>, which means a single asynchronous operation can be done at one time |
270 | C<1>, which means a single asynchronous operation can be done at one time |