All Downloads are FREE. Search and download functionalities are using the official Maven repository.

io.edurt.datacap.pinot.org.jboss.netty.util.internal.ThreadLocalRandom Maven / Gradle / Ivy

There is a newer version: 2024.03.7
Show newest version
/*
 * Copyright 2012 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/licenses/publicdomain
 */

package io.edurt.datacap.pinot.org.jboss.netty.util.internal;

import java.util.Random;

/**
 * A random number generator isolated to the current thread.  Like the
 * global {@link Random} generator used by the {@link
 * 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 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 */ public final 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 the first and only allowed call * to setSeed (inside Random constructor) to succeed. 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. */ private 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. @SuppressWarnings("unused") private long pad0, pad1, pad2, pad3, pad4, pad5, pad6, pad7; /** * The actual ThreadLocal */ private static final ThreadLocal localRandom = new ThreadLocal() { @Override protected ThreadLocalRandom initialValue() { return new ThreadLocalRandom(); } }; /** * 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 */ @Override public void setSeed(long seed) { // We rely on the fact that the superclass no-arg constructor // invokes setSeed exactly once to initialize. if (initialized) { throw new UnsupportedOperationException(); } initialized = true; rnd = (seed ^ multiplier) & mask; } @Override protected int next(int bits) { rnd = rnd * multiplier + addend & mask; return (int) (rnd >>> 48 - bits); } private static final long serialVersionUID = -5851777807851030925L; }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy