ForkJoinTest

whatsmars-common/src/test/java/org/hongxi/java/util/concurrent/ForkJoinTest.java

 package org.hongxi.java.util.concurrent;
 
+import java.util.Arrays;
+import java.util.Random;
 import java.util.concurrent.ForkJoinPool;
 import java.util.concurrent.RecursiveTask;
 import java.util.concurrent.RecursiveAction;
@@ -17,6 +19,20 @@ public class ForkJoinTest {
         ForkJoinPool forkJoinPool = new ForkJoinPool(Runtime.getRuntime().availableProcessors() * 2);
         int sum = forkJoinPool.invoke(new AccumulationTask(1, 60000));
         System.out.println(sum);
+
+        long[] array = new long[10000];
+        Random r = new Random();
+        for (int i = 0; i < array.length; i++) {
+            array[i] = r.nextInt(10000);
+        }
+        for (int i = 0; i < 10; i++) {
+            System.out.print(array[i] + " ");
+        }
+        forkJoinPool.invoke(new SortTask(array));
+        System.out.println();
+        for (int i = 0; i < 10; i++) {
+            System.out.print(array[i] + " ");
+        }
     }
 
     static class AccumulationTask extends RecursiveTask<Integer> {
@@ -47,4 +63,44 @@ public class ForkJoinTest {
             return result;
         }
     }
+
+    static class SortTask extends RecursiveAction {
+        final long[] array;
+        final int lo, hi;
+
+        SortTask(long[] array, int lo, int hi) {
+            this.array = array;
+            this.lo = lo;
+            this.hi = hi;
+        }
+
+        SortTask(long[] array) {
+            this(array, 0, array.length);
+        }
+
+        protected void compute() {
+            if (hi - lo < THRESHOLD)
+                sortSequentially(lo, hi);
+            else {
+                int mid = (lo + hi) >>> 1;
+                invokeAll(new SortTask(array, lo, mid),
+                        new SortTask(array, mid, hi));
+                merge(lo, mid, hi);
+            }
+        }
+
+        // implementation details follow:
+        static final int THRESHOLD = 1000;
+
+        void sortSequentially(int lo, int hi) {
+            Arrays.sort(array, lo, hi);
+        }
+
+        void merge(int lo, int mid, int hi) {
+            long[] buf = Arrays.copyOfRange(array, lo, mid);
+            for (int i = 0, j = lo, k = mid; i < buf.length; j++)
+                array[j] = (k == hi || buf[i] < array[k]) ?
+                        buf[i++] : array[k++];
+        }
+    }
 }