001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.io;
019
020import java.nio.ByteBuffer;
021
022import org.apache.hadoop.classification.InterfaceAudience;
023import org.apache.hadoop.classification.InterfaceStability;
024
025@InterfaceAudience.Public
026@InterfaceStability.Stable
027public interface ByteBufferPool {
028  /**
029   * Get a new direct ByteBuffer.  The pool can provide this from
030   * removing a buffer from its internal cache, or by allocating a 
031   * new buffer.
032   *
033   * @param direct     Whether the buffer should be direct.
034   * @param length     The minimum length the buffer will have.
035   * @return           A new ByteBuffer.  This ByteBuffer must be direct.
036   *                   Its capacity can be less than what was requested, but
037   *                   must be at least 1 byte.
038   */
039  ByteBuffer getBuffer(boolean direct, int length);
040
041  /**
042   * Release a buffer back to the pool.
043   * The pool may choose to put this buffer into its cache.
044   *
045   * @param buffer    a direct bytebuffer
046   */
047  void putBuffer(ByteBuffer buffer);
048}