| 10 |
|
* Recursive result-bearing ForkJoinTasks. |
| 11 |
|
* <p> For a classic example, here is a task computing Fibonacci numbers: |
| 12 |
|
* |
| 13 |
< |
* <pre> |
| 14 |
< |
* class Fibonacci extends RecursiveTask<Integer> { |
| 13 |
> |
* <pre> {@code |
| 14 |
> |
* class Fibonacci extends RecursiveTask<Integer> { |
| 15 |
|
* final int n; |
| 16 |
< |
* Fibonnaci(int n) { this.n = n; } |
| 16 |
> |
* Fibonacci(int n) { this.n = n; } |
| 17 |
|
* Integer compute() { |
| 18 |
< |
* if (n <= 1) |
| 18 |
> |
* if (n <= 1) |
| 19 |
|
* return n; |
| 20 |
|
* Fibonacci f1 = new Fibonacci(n - 1); |
| 21 |
|
* f1.fork(); |
| 22 |
|
* Fibonacci f2 = new Fibonacci(n - 2); |
| 23 |
|
* return f2.compute() + f1.join(); |
| 24 |
|
* } |
| 25 |
< |
* } |
| 26 |
< |
* </pre> |
| 25 |
> |
* }}</pre> |
| 26 |
|
* |
| 27 |
|
* However, besides being a dumb way to compute Fibonacci functions |
| 28 |
|
* (there is a simple fast linear algorithm that you'd use in |
| 32 |
|
* minimum granularity size (for example 10 here) for which you always |
| 33 |
|
* sequentially solve rather than subdividing. |
| 34 |
|
* |
| 35 |
+ |
* @since 1.7 |
| 36 |
+ |
* @author Doug Lea |
| 37 |
|
*/ |
| 38 |
|
public abstract class RecursiveTask<V> extends ForkJoinTask<V> { |
| 39 |
|
|
| 40 |
|
/** |
| 41 |
< |
* Empty contructor for use by subclasses. |
| 41 |
< |
*/ |
| 42 |
< |
protected RecursiveTask() { |
| 43 |
< |
} |
| 44 |
< |
|
| 45 |
< |
/** |
| 46 |
< |
* The result returned by compute method. |
| 41 |
> |
* The result of the computation. |
| 42 |
|
*/ |
| 43 |
|
V result; |
| 44 |
|
|
| 56 |
|
} |
| 57 |
|
|
| 58 |
|
/** |
| 59 |
< |
* Implements execution conventions for RecursiveTask |
| 59 |
> |
* Implements execution conventions for RecursiveTask. |
| 60 |
|
*/ |
| 61 |
|
protected final boolean exec() { |
| 62 |
|
result = compute(); |
