jdk/test/java/util/concurrent/FutureTask/LoopHelpers.java
author duke
Sat, 01 Dec 2007 00:00:00 +0000
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/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 * CA 95054 USA or visit www.sun.com if you need additional information or
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 * have any questions.
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 */
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/*
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 * This file is available under and governed by the GNU General Public
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 * License version 2 only, as published by the Free Software Foundation.
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 * However, the following notice accompanied the original version of this
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 * file:
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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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import java.util.concurrent.*;
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import java.util.concurrent.atomic.*;
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class LoopHelpers {
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    // Some mindless computation to do between synchronizations...
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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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     *  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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     * 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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        public void setSeed(long s) {
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            seed = s;
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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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    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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    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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}