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ConcurrentUUIDFactory.java
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ConcurrentUUIDFactory.java
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/*
*
* Copyright 2015 Netflix, Inc.
*
* 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.netflix.util.concurrent;
import com.netflix.util.UUIDFactory;
import javax.inject.Singleton;
import java.util.Random;
import java.util.UUID;
import java.util.concurrent.ThreadLocalRandom;
/**
* UUIDFactory implementation that will perform reasonably when used by multiple threads under load.
*/
@Singleton
public class ConcurrentUUIDFactory implements UUIDFactory {
@Override
public UUID generateRandomUuid() {
final Random rnd = ThreadLocalRandom.current();
long mostSig = rnd.nextLong();
long leastSig = rnd.nextLong();
// Identify this as a version 4 UUID, that is one based on a random value.
mostSig &= 0xffffffffffff0fffL;
mostSig |= 0x0000000000004000L;
// Set the variant identifier as specified for version 4 UUID values. The two
// high order bits of the lower word are required to be one and zero, respectively.
leastSig &= 0x3fffffffffffffffL;
leastSig |= 0x8000000000000000L;
return new UUID(mostSig, leastSig);
}
}