From 70df5a6f63a89c6de4afbf64774a5ddb66557985 Mon Sep 17 00:00:00 2001 From: Trustin Lee Date: Sun, 7 Jul 2013 12:26:48 +0900 Subject: [PATCH] Add ThreadLocalRandom back because it's used by ForkJoinPool now. --- .../util/internal/ThreadLocalRandom.java | 214 ++++++++++++++++++ .../util/internal/chmv8/ForkJoinPool.java | 3 +- 2 files changed, 216 insertions(+), 1 deletion(-) create mode 100644 common/src/main/java/io/netty/util/internal/ThreadLocalRandom.java diff --git a/common/src/main/java/io/netty/util/internal/ThreadLocalRandom.java b/common/src/main/java/io/netty/util/internal/ThreadLocalRandom.java new file mode 100644 index 0000000000..815ec04b6d --- /dev/null +++ b/common/src/main/java/io/netty/util/internal/ThreadLocalRandom.java @@ -0,0 +1,214 @@ +/* + * Copyright 2013 The Netty Project + * + * The Netty Project licenses this file to you under the Apache License, + * version 2.0 (the "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations + * under the License. + */ + +/* + * 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/ + */ + +package io.netty.util.internal; + +import java.util.Random; + +/** + * A random number generator isolated to the current thread. Like the + * global {@link java.util.Random} generator used by the {@link + * java.lang.Math} class, a {@code ThreadLocalRandom} is initialized + * with an internally generated seed that may not otherwise be + * modified. When applicable, use of {@code ThreadLocalRandom} rather + * than shared {@code Random} objects in concurrent programs will + * typically encounter much less overhead and contention. Use of + * {@code ThreadLocalRandom} is particularly appropriate when multiple + * tasks (for example, each a {@link io.netty.util.internal.chmv8.ForkJoinTask}) use random numbers + * in parallel in thread pools. + * + *

Usages of this class should typically be of the form: + * {@code ThreadLocalRandom.current().nextX(...)} (where + * {@code X} is {@code Int}, {@code Long}, etc). + * When all usages are of this form, it is never possible to + * accidently share a {@code ThreadLocalRandom} across multiple threads. + * + *

This class also provides additional commonly used bounded random + * generation methods. + * + * @since 1.7 + * @author Doug Lea + */ +@SuppressWarnings("all") +public class ThreadLocalRandom extends Random { + // same constants as Random, but must be redeclared because private + private static final long multiplier = 0x5DEECE66DL; + private static final long addend = 0xBL; + private static final long mask = (1L << 48) - 1; + + /** + * The random seed. We can't use super.seed. + */ + private long rnd; + + /** + * Initialization flag to permit calls to setSeed to succeed only + * while executing the Random constructor. We can't allow others + * since it would cause setting seed in one part of a program to + * unintentionally impact other usages by the thread. + */ + boolean initialized; + + // Padding to help avoid memory contention among seed updates in + // different TLRs in the common case that they are located near + // each other. + private long pad0, pad1, pad2, pad3, pad4, pad5, pad6, pad7; + + /** + * The actual ThreadLocal + */ + private static final ThreadLocal localRandom = + new ThreadLocal() { + protected ThreadLocalRandom initialValue() { + return new ThreadLocalRandom(); + } + }; + + + /** + * Constructor called only by localRandom.initialValue. + */ + ThreadLocalRandom() { + super(); + initialized = true; + } + + /** + * Returns the current thread's {@code ThreadLocalRandom}. + * + * @return the current thread's {@code ThreadLocalRandom} + */ + public static ThreadLocalRandom current() { + return localRandom.get(); + } + + /** + * Throws {@code UnsupportedOperationException}. Setting seeds in + * this generator is not supported. + * + * @throws UnsupportedOperationException always + */ + public void setSeed(long seed) { + if (initialized) + throw new UnsupportedOperationException(); + rnd = (seed ^ multiplier) & mask; + } + + protected int next(int bits) { + rnd = (rnd * multiplier + addend) & mask; + return (int) (rnd >>> (48-bits)); + } + + /** + * Returns a pseudorandom, uniformly distributed value between the + * given least value (inclusive) and bound (exclusive). + * + * @param least the least value returned + * @param bound the upper bound (exclusive) + * @throws IllegalArgumentException if least greater than or equal + * to bound + * @return the next value + */ + public int nextInt(int least, int bound) { + if (least >= bound) + throw new IllegalArgumentException(); + return nextInt(bound - least) + least; + } + + /** + * Returns a pseudorandom, uniformly distributed value + * between 0 (inclusive) and the specified value (exclusive). + * + * @param n the bound on the random number to be returned. Must be + * positive. + * @return the next value + * @throws IllegalArgumentException if n is not positive + */ + public long nextLong(long n) { + if (n <= 0) + throw new IllegalArgumentException("n must be positive"); + // Divide n by two until small enough for nextInt. On each + // iteration (at most 31 of them but usually much less), + // randomly choose both whether to include high bit in result + // (offset) and whether to continue with the lower vs upper + // half (which makes a difference only if odd). + long offset = 0; + while (n >= Integer.MAX_VALUE) { + int bits = next(2); + long half = n >>> 1; + long nextn = ((bits & 2) == 0) ? half : n - half; + if ((bits & 1) == 0) + offset += n - nextn; + n = nextn; + } + return offset + nextInt((int) n); + } + + /** + * Returns a pseudorandom, uniformly distributed value between the + * given least value (inclusive) and bound (exclusive). + * + * @param least the least value returned + * @param bound the upper bound (exclusive) + * @return the next value + * @throws IllegalArgumentException if least greater than or equal + * to bound + */ + public long nextLong(long least, long bound) { + if (least >= bound) + throw new IllegalArgumentException(); + return nextLong(bound - least) + least; + } + + /** + * Returns a pseudorandom, uniformly distributed {@code double} value + * between 0 (inclusive) and the specified value (exclusive). + * + * @param n the bound on the random number to be returned. Must be + * positive. + * @return the next value + * @throws IllegalArgumentException if n is not positive + */ + public double nextDouble(double n) { + if (n <= 0) + throw new IllegalArgumentException("n must be positive"); + return nextDouble() * n; + } + + /** + * Returns a pseudorandom, uniformly distributed value between the + * given least value (inclusive) and bound (exclusive). + * + * @param least the least value returned + * @param bound the upper bound (exclusive) + * @return the next value + * @throws IllegalArgumentException if least greater than or equal + * to bound + */ + public double nextDouble(double least, double bound) { + if (least >= bound) + throw new IllegalArgumentException(); + return nextDouble() * (bound - least) + least; + } + + private static final long serialVersionUID = -5851777807851030925L; +} diff --git a/common/src/main/java/io/netty/util/internal/chmv8/ForkJoinPool.java b/common/src/main/java/io/netty/util/internal/chmv8/ForkJoinPool.java index 6a962ead87..bfe4e9d269 100644 --- a/common/src/main/java/io/netty/util/internal/chmv8/ForkJoinPool.java +++ b/common/src/main/java/io/netty/util/internal/chmv8/ForkJoinPool.java @@ -22,6 +22,8 @@ package io.netty.util.internal.chmv8; +import io.netty.util.internal.ThreadLocalRandom; + import java.lang.Thread.UncaughtExceptionHandler; import java.util.ArrayList; import java.util.Arrays; @@ -34,7 +36,6 @@ import java.util.concurrent.ExecutorService; import java.util.concurrent.Future; import java.util.concurrent.RejectedExecutionException; import java.util.concurrent.RunnableFuture; -import java.util.concurrent.ThreadLocalRandom; import java.util.concurrent.TimeUnit; /**