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.hadoop.chukwa.datacollection;
  
  
  import java.util.List;
  import org.apache.hadoop.chukwa.Chunk;
  
  /**
   * A generic interface for queues of Chunks.
   * 
   * Differs from a normal queue interface primarily by having collect().
   */
  public interface ChunkQueue extends ChunkReceiver {
    /**
     * Add a chunk to the queue, blocking if queue is full.
     * 
     * @param chunk A binary blob
     * @throws InterruptedException if thread is interrupted while blocking
     */
    public void add(Chunk chunk) throws InterruptedException;
  
    /**
     * Return at least one, and no more than count, Chunks into chunks. Blocks if
     * queue is empty.
     * @param chunks List of binary blobs
     * @param count maximum number of chunk to return
     * @throws InterruptedException if thread is interrupted while collecting
     */
    public void collect(List<Chunk> chunks, int count)
        throws InterruptedException;
  
    /**
     * Return an approximation of the number of chunks in the queue currently. No
     * guarantees are made about the accuracy of this number.
     * @return number of chunks in the queue currently
     */
    public int size();
  }
  