| … | |
… | |
| 49 | silly, but illustrates the use of events. |
49 | silly, but illustrates the use of events. |
| 50 | |
50 | |
| 51 | First the parent process: |
51 | First the parent process: |
| 52 | |
52 | |
| 53 | use AnyEvent; |
53 | use AnyEvent; |
| 54 | use AnyEvent::Fork; |
|
|
| 55 | use AnyEvent::Fork::RPC; |
54 | use AnyEvent::Fork::RPC; |
| 56 | |
55 | |
| 57 | my $done = AE::cv; |
56 | my $done = AE::cv; |
| 58 | |
57 | |
| 59 | my $rpc = AnyEvent::Fork |
58 | my $rpc = AnyEvent::Fork |
| … | |
… | |
| 174 | child process may exit at any time, so you should call C<$done> only when |
173 | child process may exit at any time, so you should call C<$done> only when |
| 175 | you really I<are> done. |
174 | you really I<are> done. |
| 176 | |
175 | |
| 177 | =head2 Example 2: Asynchronous Backend |
176 | =head2 Example 2: Asynchronous Backend |
| 178 | |
177 | |
| 179 | #TODO |
178 | This example implements multiple count-downs in the child, using |
|
|
179 | L<AnyEvent> timers. While this is a bit silly (one could use timers in te |
|
|
180 | parent just as well), it illustrates the ability to use AnyEvent in the |
|
|
181 | child and the fact that responses can arrive in a different order then the |
|
|
182 | requests. |
|
|
183 | |
|
|
184 | It also shows how to embed the actual child code into a C<__DATA__> |
|
|
185 | section, so it doesn't need any external files at all. |
|
|
186 | |
|
|
187 | And when your parent process is often busy, and you have stricter timing |
|
|
188 | requirements, then running timers in a child process suddenly doesn't look |
|
|
189 | so silly anymore. |
|
|
190 | |
|
|
191 | Without further ado, here is the code: |
|
|
192 | |
|
|
193 | use AnyEvent; |
|
|
194 | use AnyEvent::Fork::RPC; |
|
|
195 | |
|
|
196 | my $done = AE::cv; |
|
|
197 | |
|
|
198 | my $rpc = AnyEvent::Fork |
|
|
199 | ->new |
|
|
200 | ->require ("AnyEvent::Fork::RPC::Async") |
|
|
201 | ->eval (do { local $/; <DATA> }) |
|
|
202 | ->AnyEvent::Fork::RPC::run ("run", |
|
|
203 | async => 1, |
|
|
204 | on_error => sub { warn "FATAL: $_[0]"; exit 1 }, |
|
|
205 | on_event => sub { print $_[0] }, |
|
|
206 | on_destroy => $done, |
|
|
207 | ); |
|
|
208 | |
|
|
209 | for my $count (3, 2, 1) { |
|
|
210 | $rpc->($count, sub { |
|
|
211 | warn "job $count finished\n"; |
|
|
212 | }); |
|
|
213 | } |
|
|
214 | |
|
|
215 | undef $rpc; |
|
|
216 | |
|
|
217 | $done->recv; |
|
|
218 | |
|
|
219 | __DATA__ |
|
|
220 | |
|
|
221 | # this ends up in main, as we don't use a package declaration |
|
|
222 | |
|
|
223 | use AnyEvent; |
|
|
224 | |
|
|
225 | sub run { |
|
|
226 | my ($done, $count) = @_; |
|
|
227 | |
|
|
228 | my $n; |
|
|
229 | |
|
|
230 | AnyEvent::Fork::RPC::event "starting to count up to $count\n"; |
|
|
231 | |
|
|
232 | my $w; $w = AE::timer 1, 1, sub { |
|
|
233 | ++$n; |
|
|
234 | |
|
|
235 | AnyEvent::Fork::RPC::event "count $n of $count\n"; |
|
|
236 | |
|
|
237 | if ($n == $count) { |
|
|
238 | undef $w; |
|
|
239 | $done->(); |
|
|
240 | } |
|
|
241 | }; |
|
|
242 | } |
|
|
243 | |
|
|
244 | The parent part (the one before the C<__DATA__> section) isn't very |
|
|
245 | different from the earlier examples. It sets async mode, preloads |
|
|
246 | the backend module (so the C<AnyEvent::Fork::RPC::event> function is |
|
|
247 | declared), uses a slightly different C<on_event> handler (which we use |
|
|
248 | simply for logging purposes) and then, instead of loading a module with |
|
|
249 | the actual worker code, it C<eval>'s the code from the data section in the |
|
|
250 | child process. |
|
|
251 | |
|
|
252 | It then starts three countdowns, from 3 to 1 seconds downwards, destroys |
|
|
253 | the rpc object so the example finishes eventually, and then just waits for |
|
|
254 | the stuff to trickle in. |
|
|
255 | |
|
|
256 | The worker code uses the event function to log some progress messages, but |
|
|
257 | mostly just creates a recurring one-second timer. |
|
|
258 | |
|
|
259 | The timer callback increments a counter, logs a message, and eventually, |
|
|
260 | when the count has been reached, calls the finish callback. |
|
|
261 | |
|
|
262 | On my system, this results in the following output. Since all timers fire |
|
|
263 | at roughly the same time, the actual order isn't guaranteed, but the order |
|
|
264 | shown is very likely what you would get, too. |
|
|
265 | |
|
|
266 | starting to count up to 3 |
|
|
267 | starting to count up to 2 |
|
|
268 | starting to count up to 1 |
|
|
269 | count 1 of 3 |
|
|
270 | count 1 of 2 |
|
|
271 | count 1 of 1 |
|
|
272 | job 1 finished |
|
|
273 | count 2 of 2 |
|
|
274 | job 2 finished |
|
|
275 | count 2 of 3 |
|
|
276 | count 3 of 3 |
|
|
277 | job 3 finished |
|
|
278 | |
|
|
279 | While the overall ordering isn't guaranteed, the async backend still |
|
|
280 | guarantees that events and responses are delivered to the parent process |
|
|
281 | in the exact same ordering as they were generated in the child process. |
|
|
282 | |
|
|
283 | And unless your system is I<very> busy, it should clearly show that the |
|
|
284 | job started last will finish first, as it has the lowest count. |
|
|
285 | |
|
|
286 | This concludes the async example. Since L<AnyEvent::Fork> does not |
|
|
287 | actually fork, you are free to use about any module in the child, not just |
|
|
288 | L<AnyEvent>, but also L<IO::AIO>, or L<Tk> for example. |
| 180 | |
289 | |
| 181 | =head1 PARENT PROCESS USAGE |
290 | =head1 PARENT PROCESS USAGE |
| 182 | |
291 | |
| 183 | This module exports nothing, and only implements a single function: |
292 | This module exports nothing, and only implements a single function: |
| 184 | |
293 | |
