diff -r 000000000000 -r 212417b74b72 rt/emul/compact/src/main/java/java/util/concurrent/ThreadLocalRandom.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/rt/emul/compact/src/main/java/java/util/concurrent/ThreadLocalRandom.java Sat Mar 19 10:46:31 2016 +0100 @@ -0,0 +1,226 @@ +/* + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ + +/* + * This file is available under and governed by the GNU General Public + * License version 2 only, as published by the Free Software Foundation. + * However, the following notice accompanied the original version of this + * file: + * + * 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 java.util.concurrent; + +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 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
+ */
+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