ratis-common/src/main/java/org/apache/ratis/util/DataBlockingQueue.java

/*
 * 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.ratis.util;

import org.apache.ratis.util.function.CheckedFunctionWithTimeout;
import org.apache.ratis.util.function.TriConsumer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.List;
import java.util.Objects;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.ToIntFunction;

/**
 * A queue for data elements
 * such that the queue imposes limits on both number of elements and the data size in bytes.
 *
 * Null element is NOT supported.
 *
 * This class is threadsafe.
 */
public class DataBlockingQueue<E> extends DataQueue<E> {
  public static final Logger LOG = LoggerFactory.getLogger(DataBlockingQueue.class);

  private final Lock lock = new ReentrantLock();
  private final Condition notFull  = lock.newCondition();
  private final Condition notEmpty = lock.newCondition();

  public DataBlockingQueue(Object name, SizeInBytes byteLimit, int elementLimit, ToIntFunction<E> getNumBytes) {
    super(name, byteLimit, elementLimit, getNumBytes);
  }

  @Override
  public int getNumBytes() {
    try(AutoCloseableLock auto = AutoCloseableLock.acquire(lock)) {
      return super.getNumBytes();
    }
  }

  @Override
  public int getNumElements() {
    try(AutoCloseableLock auto = AutoCloseableLock.acquire(lock)) {
      return super.getNumElements();
    }
  }

  @Override
  public void clear() {
    try(AutoCloseableLock auto = AutoCloseableLock.acquire(lock)) {
      super.clear();
      notFull.signal();
    }
  }

  @Override
  public boolean offer(E element) {
    Objects.requireNonNull(element, "element == null");
    try(AutoCloseableLock auto = AutoCloseableLock.acquire(lock)) {
      if (super.offer(element)) {
        notEmpty.signal();
        return true;
      }
      return false;
    }
  }

  /**
   * Adds an element to this queue, waiting up to the given timeout.
   *
   * @return true if the element is added successfully;
   *         otherwise, the element is not added, return false.
   */
  public boolean offer(E element, TimeDuration timeout) throws InterruptedException {
    Objects.requireNonNull(element, "element == null");
    long nanos = timeout.toLong(TimeUnit.NANOSECONDS);
    try(AutoCloseableLock auto = AutoCloseableLock.acquire(lock)) {
      for(;;) {
        if (super.offer(element)) {
          notEmpty.signal();
          return true;
        }
        if (nanos <= 0) {
          return false;
        }
        nanos = notFull.awaitNanos(nanos);
      }

    }
  }

  @Override
  public E poll() {
    try(AutoCloseableLock auto = AutoCloseableLock.acquire(lock)) {
      final E polled = super.poll();
      if (polled != null) {
        notFull.signal();
      }
      return polled;
    }
  }

  /**
   * Poll out the head element from this queue, waiting up to the given timeout.
   */
  public E poll(TimeDuration timeout) throws InterruptedException {
    long nanos = timeout.toLong(TimeUnit.NANOSECONDS);
    try(AutoCloseableLock auto = AutoCloseableLock.acquire(lock)) {
      for(;;) {
        final E polled = super.poll();
        if (polled != null) {
          notFull.signal();
          return polled;
        }
        if (nanos <= 0) {
          return null;
        }
        nanos = notEmpty.awaitNanos(nanos);
      }
    }
  }

  @Override
  public <RESULT, THROWABLE extends Throwable> List<RESULT> pollList(long timeoutMs,
      CheckedFunctionWithTimeout<E, RESULT, THROWABLE> getResult,
      TriConsumer<E, TimeDuration, TimeoutException> timeoutHandler) throws THROWABLE {
    try(AutoCloseableLock auto = AutoCloseableLock.acquire(lock)) {
      final List<RESULT> results = super.pollList(timeoutMs, getResult, timeoutHandler);
      if (!results.isEmpty()) {
        notFull.signal();
      }
      return results;
    }
  }
}