/*
* Copyright 2000-2014 JetBrains s.r.o.
*
* Licensed 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.
*/
package com.intellij.util.containers;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
class ThreadLocalRandom {
public static int getProbe() {
return tlr.get().threadLocalRandomProbe;
}
public static void localInit() {
int p = probeGenerator.addAndGet(PROBE_INCREMENT);
int probe = (p == 0) ? 1 : p; // skip 0
long seed = mix64(seeder.getAndAdd(SEEDER_INCREMENT));
Tlr t = tlr.get();
t.threadLocalRandomProbe = probe;
t.threadLocalRandomSeed = seed;
}
/**
* Pseudo-randomly advances and records the given probe value for the
* given thread.
*/
static int advanceProbe(int probe) {
probe ^= probe << 13; // xorshift
probe ^= probe >>> 17;
probe ^= probe << 5;
tlr.get().threadLocalRandomProbe = probe;
return probe;
}
static class Tlr {
/**
* The current seed for a ThreadLocalRandom
*/
long threadLocalRandomSeed;
/**
* Probe hash value; nonzero if threadLocalRandomSeed initialized
*/
int threadLocalRandomProbe;
}
private static final ThreadLocal<Tlr> tlr = new ThreadLocal<Tlr>() {
@Override
protected Tlr initialValue() {
return new Tlr();
}
};
private static final AtomicInteger probeGenerator = new AtomicInteger();
/**
* The increment for generating probe values
*/
private static final int PROBE_INCREMENT = 0x9e3779b9;
/**
* The increment of seeder per new instance
*/
private static final long SEEDER_INCREMENT = 0xbb67ae8584caa73bL;
/**
* The next seed for default constructors.
*/
private static final AtomicLong seeder = new AtomicLong(/*initialSeed()*/);
private static long mix64(long z) {
z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
return z ^ (z >>> 33);
}
}