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root/jsr166/jsr166/src/test/loops/DynamicLeftSpineFib.java

Comparing jsr166/src/test/loops/DynamicLeftSpineFib.java (file contents):
Revision 1.8 by jsr166, Mon Nov 16 04:16:43 2009 UTC vs.
Revision 1.16 by jsr166, Thu Jan 15 18:34:19 2015 UTC

#	Line 1 | Line 1
1		/*
2		* Written by Doug Lea with assistance from members of JCP JSR-166
3		* Expert Group and released to the public domain, as explained at
4	<	* http://creativecommons.org/licenses/publicdomain
4	>	* http://creativecommons.org/publicdomain/zero/1.0/
5		*/
6
7		import java.util.*;
#	Line 9 | Line 9 | import java.util.concurrent.*;
9
10		public final class DynamicLeftSpineFib extends RecursiveAction {
11
12	–	// Performance-tuning constant:
12		static long lastStealCount;
13
14		public static void main(String[] args) throws Exception {
15		int procs = 0;
16	<	int num = 43;
16	>	int num = 45;
17		try {
18		if (args.length > 0)
19		procs = Integer.parseInt(args[0]);
#	Line 26 | Line 25 | public final class DynamicLeftSpineFib e
25		return;
26		}
27
29	–
28		for (int reps = 0; reps < 2; ++reps) {
29	<	ForkJoinPool g = procs == 0? new ForkJoinPool() :
29	>	ForkJoinPool g = (procs == 0) ? new ForkJoinPool() :
30		new ForkJoinPool(procs);
31		lastStealCount = g.getStealCount();
32	<	for (int i = 0; i < 10; ++i) {
32	>	for (int i = 0; i < 20; ++i) {
33		test(g, num);
34		}
35		System.out.println(g);
36		g.shutdown();
37	+	if (!g.awaitTermination(10, TimeUnit.SECONDS))
38	+	throw new Error();
39	+	Thread.sleep(1000);
40		}
41		}
42
#	Line 57 | Line 58 | public final class DynamicLeftSpineFib e
58		System.out.println();
59		}
60
60	–
61		// Initialized with argument; replaced with result
62		int number;
63		DynamicLeftSpineFib next;
#	Line 69 | Line 69 | public final class DynamicLeftSpineFib e
69		int getAnswer() {
70		return number;
71		}
72	+	public void compute() {
73	+	number = fib(number);
74	+	}
75
76	<	public final void compute() {
77	<	int n = number;
78	<	if (n > 1) {
79	<	int r = 0;
80	<	DynamicLeftSpineFib rt = null;
81	<	while (getSurplusQueuedTaskCount() <= 3) {
82	<	int m = n - 2;
83	<	n -= 1;
84	<	if (m <= 1) {
85	<	r += m;
86	<	if (n > 1) {
87	<	r += n - 2;
88	<	n -= 1;
86	<	}
87	<	break;
76	>	static final int fib(int n) {
77	>	if (n <= 1)
78	>	return n;
79	>	int r = 0;
80	>	DynamicLeftSpineFib rt = null;
81	>	while (getSurplusQueuedTaskCount() <= 3) {
82	>	int m = n - 2;
83	>	n -= 1;
84	>	if (m <= 1) {
85	>	r += m;
86	>	if (n > 1) {
87	>	r += n - 2;
88	>	n -= 1;
89		}
90	<	(rt = new DynamicLeftSpineFib(m, rt)).fork();
90	>	break;
91		}
92	<	r += seqFib(n);
93	<	while (rt != null) {
94	<	if (rt.tryUnfork()) rt.compute(); else rt.helpJoin();
92	>	(rt = new DynamicLeftSpineFib(m, rt)).fork();
93	>	}
94	>	if (n <= 1)
95	>	r += n;
96	>	else
97	>	r += seqFib(n - 2) + fib(n - 1);
98	>	if (rt != null)
99	>	r += collectRights(rt);
100	>	return r;
101	>	}
102	>
103	>	static final int collectRights(DynamicLeftSpineFib rt) {
104	>	int r = 0;
105	>	while (rt != null) {
106	>	DynamicLeftSpineFib rn = rt.next;
107	>	rt.next = null;
108	>	if (rt.tryUnfork())
109	>	r += fib(rt.number);
110	>	else {
111	>	rt.join();
112		r += rt.number;
95	–	rt = rt.next;
113		}
114	<	number = r;
114	>	rt = rn;
115		}
116	+	return r;
117		}
118
119		// Sequential version for arguments less than threshold
120	<	static int seqFib(int n) {
121	<	if (n <= 1)
122	<	return n;
123	<	else
124	<	return seqFib(n-1) + seqFib(n-2);
120	>	static final int seqFib(int n) { // unroll left only
121	>	int r = 1;
122	>	do {
123	>	int m = n - 2;
124	>	r += m <= 1 ? m : seqFib(m);
125	>	} while (--n > 1);
126	>	return r;
127		}
128
129		}
110	–

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