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|
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public class Finals { |
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static int npairs = 2; |
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static int iters = 10000000; |
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static final int LEN = 4; |
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static final Long[] nums = new Long[LEN]; |
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static volatile boolean done; |
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static volatile long total; |
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|
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public static void main(String[] args) { |
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for (int i = 0; i < LEN; ++i) |
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nums[i] = new Long(i+1); |
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Thread[] ps = new Thread[npairs]; |
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Thread[] as = new Reader[npairs]; |
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for (int i = 0; i < npairs; ++i) { |
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ps[i] = new Writer(); |
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as[i] = new Reader(); |
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} |
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for (int i = 0; i < as.length; ++i) { |
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ps[i].start(); |
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as[i].start(); |
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} |
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} |
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|
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static long nextRandom(long seed) { |
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return (seed * 0x5DEECE66DL + 0xBL) & ((1L << 48) - 1); |
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} |
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|
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static long initialSeed(Object x) { |
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return (System.currentTimeMillis() + x.hashCode()) | 1; |
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} |
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|
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static class Writer extends Thread { |
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public void run() { |
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long s = initialSeed(this); |
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int n = iters; |
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while (!done && n-- > 0) { |
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int k = (int)(s & (LEN-1)); |
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int l = (k+1) & (LEN-1); |
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nums[k] = new Long(s); |
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nums[l] = new Long(s); |
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s = nextRandom(s); |
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if (s == 0) s = initialSeed(this); |
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} |
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done = true; |
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total += s; |
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} |
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} |
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|
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static class Reader extends Thread { |
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public void run() { |
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int n = iters; |
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long s = initialSeed(this); |
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while (s != 0 && n > 0) { |
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long nexts = nums[(int)(s & (LEN-1))].longValue(); |
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if (nexts != s) |
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--n; |
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else if (done) |
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break; |
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s = nexts; |
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} |
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done = true; |
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total += s; |
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if (s == 0) |
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throw new Error("Saw uninitialized value"); |
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} |
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} |
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} |
