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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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*/ |
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/** |
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* Misc utilities in JSR166 performance tests |
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*/ |
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|
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import java.util.concurrent.*; |
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import java.util.concurrent.atomic.*; |
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|
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class LoopHelpers { |
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|
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static final SimpleRandom staticRNG = new SimpleRandom(); |
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|
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// Some mindless computation to do between synchronizations... |
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|
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/** |
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* generates 32 bit pseudo-random numbers. |
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* Adapted from http://www.snippets.org |
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*/ |
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public static int compute1(int x) { |
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int lo = 16807 * (x & 0xFFFF); |
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int hi = 16807 * (x >>> 16); |
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lo += (hi & 0x7FFF) << 16; |
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if ((lo & 0x80000000) != 0) { |
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lo &= 0x7fffffff; |
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++lo; |
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} |
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lo += hi >>> 15; |
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if (lo == 0 || (lo & 0x80000000) != 0) { |
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lo &= 0x7fffffff; |
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++lo; |
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} |
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return lo; |
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} |
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|
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/** |
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* Computes a linear congruential random number a random number |
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* of times. |
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*/ |
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public static int compute2(int x) { |
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int loops = (x >>> 4) & 7; |
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while (loops-- > 0) { |
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x = (x * 2147483647) % 16807; |
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} |
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return x; |
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} |
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|
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/** |
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* Yet another random number generator |
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*/ |
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public static int compute3(int x) { |
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int t = (x % 127773) * 16807 - (x / 127773) * 2836; |
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return (t > 0)? t : t + 0x7fffffff; |
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} |
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|
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/** |
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* Yet another random number generator |
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*/ |
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public static int compute4(int x) { |
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return x * 134775813 + 1; |
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} |
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|
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|
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/** |
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* Yet another random number generator |
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*/ |
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public static int compute5(int x) { |
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return 36969 * (x & 65535) + (x >> 16); |
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} |
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|
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|
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/** |
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* An actually useful random number generator, but unsynchronized. |
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* Basically same as java.util.Random. |
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*/ |
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public static class SimpleRandom { |
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private final static long multiplier = 0x5DEECE66DL; |
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private final static long addend = 0xBL; |
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private final static long mask = (1L << 48) - 1; |
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static final AtomicLong seq = new AtomicLong(1); |
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private long seed = System.nanoTime() + seq.getAndIncrement(); |
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|
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public void setSeed(long s) { |
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seed = s; |
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} |
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|
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public int next() { |
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long nextseed = (seed * multiplier + addend) & mask; |
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seed = nextseed; |
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return ((int)(nextseed >>> 17)) & 0x7FFFFFFF; |
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} |
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} |
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|
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public static class BarrierTimer implements Runnable { |
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public volatile long startTime; |
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public volatile long endTime; |
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public void run() { |
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long t = System.nanoTime(); |
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if (startTime == 0) |
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startTime = t; |
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else |
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endTime = t; |
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} |
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public void clear() { |
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startTime = 0; |
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endTime = 0; |
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} |
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public long getTime() { |
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return endTime - startTime; |
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} |
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} |
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|
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public static String rightJustify(long n) { |
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// There's probably a better way to do this... |
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String field = " "; |
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String num = Long.toString(n); |
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if (num.length() >= field.length()) |
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return num; |
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StringBuffer b = new StringBuffer(field); |
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b.replace(b.length()-num.length(), b.length(), num); |
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return b.toString(); |
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} |
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|
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} |
