--- jsr166/src/test/loops/DynamicLeftSpineFib.java	2009/10/29 23:14:43	1.3
+++ jsr166/src/test/loops/DynamicLeftSpineFib.java	2015/09/12 19:09:00	1.18
@@ -1,15 +1,19 @@
-//import jsr166y.*;
+/*
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
 import java.util.*;
 import java.util.concurrent.*;
 
 public final class DynamicLeftSpineFib extends RecursiveAction {
 
-    // Performance-tuning constant:
     static long lastStealCount;
 
     public static void main(String[] args) throws Exception {
         int procs = 0;
-        int num = 43;
+        int num = 45;
         try {
             if (args.length > 0)
                 procs = Integer.parseInt(args[0]);
@@ -17,20 +21,24 @@ public final class DynamicLeftSpineFib e
                 num = Integer.parseInt(args[1]);
         }
         catch (Exception e) {
-            System.out.println("Usage: java DynamicLeftSpineFib <threads> <number> [<sequentialThreshold>]");
+            System.out.println("Usage: java DynamicLeftSpineFib <threads> <number> [<sequntialThreshold>]");
             return;
         }
 
-
         for (int reps = 0; reps < 2; ++reps) {
-            ForkJoinPool g = procs == 0? new ForkJoinPool() :
+            ForkJoinPool g = (procs == 0) ? ForkJoinPool.commonPool() :
                 new ForkJoinPool(procs);
             lastStealCount = g.getStealCount();
-            for (int i = 0; i < 10; ++i) {
+            for (int i = 0; i < 20; ++i) {
                 test(g, num);
             }
             System.out.println(g);
-            g.shutdown();
+            if (g != ForkJoinPool.commonPool()) {
+                g.shutdown();
+                if (!g.awaitTermination(10, TimeUnit.SECONDS))
+                    throw new Error();
+            }
+            Thread.sleep(1000);
         }
     }
 
@@ -42,7 +50,7 @@ public final class DynamicLeftSpineFib e
         long time = System.currentTimeMillis() - start;
         double secs = ((double)time) / 1000.0;
         long result = f.getAnswer();
-        System.out.print("DynamicLeftSpineFib " + num + " = " + result);
+        System.out.print("DLSFib " + num + " = " + result);
         System.out.printf("\tTime: %7.3f", secs);
         long sc = g.getStealCount();
         long ns = sc - lastStealCount;
@@ -52,7 +60,6 @@ public final class DynamicLeftSpineFib e
         System.out.println();
     }
 
-
     // Initialized with argument; replaced with result
     int number;
     DynamicLeftSpineFib next;
@@ -65,30 +72,54 @@ public final class DynamicLeftSpineFib e
         return number;
     }
 
-    public final void compute() {
-        int n = number;
-        if (n > 1) {
-            DynamicLeftSpineFib rt = null;
-            while (n > 1 && getSurplusQueuedTaskCount() <= 3) {
-                (rt = new DynamicLeftSpineFib(n - 2, rt)).fork();
-                n -= 1;
-            }
-            int r = seqFib(n);
-            while (rt != null) {
-                if (rt.tryUnfork()) rt.compute(); else rt.helpJoin();
+    public void compute() {
+        number = fib(number);
+    }
+
+    static final int fib(int n) {
+        if (n <= 1)
+            return n;
+        int r = 0;
+        DynamicLeftSpineFib rt = null;
+        while (getSurplusQueuedTaskCount() <= 3) {
+            int m = n - 2;
+            if (m <= 1)
+                r += m;
+            else
+                (rt = new DynamicLeftSpineFib(m, rt)).fork();
+            if (--n <= 1)
+                break;
+        }
+        r += n <= 1 ? n : seqFib(n);
+        if (rt != null)
+            r += collectRights(rt);
+        return r;
+    }
+
+    static final int collectRights(DynamicLeftSpineFib rt) {
+        int r = 0;
+        while (rt != null) {
+            DynamicLeftSpineFib rn = rt.next;
+            rt.next = null;
+            if (rt.tryUnfork())
+                r += fib(rt.number);
+            else {
+                rt.join();
                 r += rt.number;
-                rt = rt.next;
             }
-            number = r;
+            rt = rn;
         }
+        return r;
     }
 
-    // Sequential version for arguments less than threshold
-    static int seqFib(int n) {
-        if (n <= 1)
-            return n;
-        else
-            return seqFib(n-1) + seqFib(n-2);
+    /** Sequential version for arguments less than threshold */
+    static final int seqFib(int n) { // unroll left only
+        int r = 1;
+        do {
+            int m = n - 2;
+            r += m <= 1 ? m : seqFib(m);
+        } while (--n > 1);
+        return r;
     }
 
 }