NoLock.java example

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// Copyright 2017 JanusGraph Authors
//
// 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 org.janusgraph.diskstorage.util;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

/**
 * Implementation of a lock that has no effect, i.e. does not actually lock anything.
 *
 * @author Matthias Broecheler (me@matthiasb.com)
 */

public class NoLock implements Lock {

    public static final Lock INSTANCE = new NoLock();

    private NoLock() {}

    public static final Lock getLock() {
        return INSTANCE;
    }

    @Override
    public void lock() {
    }

    @Override
    public void lockInterruptibly() throws InterruptedException {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean tryLock() {
        return true;
    }

    @Override
    public boolean tryLock(long l, TimeUnit timeUnit) throws InterruptedException {
        return true;
    }

    @Override
    public void unlock() {

    }

    @Override
    public Condition newCondition() {
        throw new UnsupportedOperationException();
    }

}