content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF 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.
   */
  package org.apache.beam.sdk.util;
  
  import java.io.Serializable;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.locks.Condition;
  import java.util.concurrent.locks.Lock;
  import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
  import org.checkerframework.checker.nullness.qual.NonNull;
  
  /**
   * A lock which can always be acquired. It should not be used when a proper lock is required, but it
   * is useful as a performance optimization when locking is not necessary but the code paths have to
   * be shared between the locking and the non-locking variant.
   */
  public class NoopLock implements Lock, Serializable {
  
    private static @MonotonicNonNull NoopLock instance;
  
    public static @NonNull NoopLock get() {
      if (instance == null) {
        instance = new NoopLock();
      }
      return instance;
    }
  
    private NoopLock() {}
  
    @Override
    public void lock() {}
  
    @Override
    public void lockInterruptibly() {}
  
    @Override
    public boolean tryLock() {
      return true;
    }
  
    @Override
    public boolean tryLock(long time, TimeUnit unit) {
      return true;
    }
  
    @Override
    public void unlock() {}
  
    @Override
    public Condition newCondition() {
      throw new UnsupportedOperationException("Not implemented");
    }
  }
  