package forkjoin;

import java.util.concurrent.*;

public class ForkJoinTest {

public static void main(String[] args) {

// TODO Auto-generated method stub

final int SIZE=10000000;

double[] numbers=new double[SIZE];

for(int i=0;i<SIZE;i++)

numbers[i]=Math.random();

Counter counter=new Counter(numbers,0,numbers.length,new Filter(){

public boolean accept(double x){

return x>0.5;

}

});

ForkJoinPool pool=new ForkJoinPool();

pool.invoke(counter);

System.out.println(counter.join());

}

}

interface Filter{

boolean accept(double t);

}

class Counter extends RecursiveTask<Integer>{

public static final int THRESHOLD=1000;

private double[] values;

private int from;

private int to;

private Filter filter;

public Counter(double[] values,int from,int to,Filter filter){

this.values=values;

this.from=from;

this.to=to;

this.filter=filter;

}

protected Integer compute(){

if(to-from<THRESHOLD){

int count=0;

for(int i=from;i<to;i++){

if(filter.accept(values[i]))

count++;

}

return count;

}

else

{

int mid=(from+to)/2;

Counter first=new Counter(values,from,mid,filter);

Counter second=new Counter(values,mid,to,filter);

invokeAll(first,second);

return first.join()+second.join();

}

}

}