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 */
018
019package org.apache.hadoop.hbase.io;
020
021import java.io.IOException;
022
023import org.apache.hadoop.hbase.Cell;
024import org.apache.yetus.audience.InterfaceAudience;
025import org.apache.yetus.audience.InterfaceStability;
026
027/**
028 * Accepts a stream of Cells. This can be used to build a block of cells during compactions
029 * and flushes, or to build a byte[] to send to the client. This could be backed by a
030 * List<KeyValue>, but more efficient implementations will append results to a
031 * byte[] to eliminate overhead, and possibly encode the cells further.
032 * <p>To read Cells, use {@link org.apache.hadoop.hbase.CellScanner}
033 * @see org.apache.hadoop.hbase.CellScanner
034 */
035@InterfaceAudience.Private
036@InterfaceStability.Evolving
037public interface CellOutputStream {
038  /**
039   * Implementation must copy the entire state of the Cell. If the written Cell is modified
040   * immediately after the write method returns, the modifications must have absolutely no effect
041   * on the copy of the Cell that was added in the write.
042   * @param cell Cell to write out
043   * @throws IOException
044   */
045  void write(Cell cell) throws IOException;
046
047  /**
048   * Let the implementation decide what to do.  Usually means writing accumulated data into a
049   * byte[] that can then be read from the implementation to be sent to disk, put in the block
050   * cache, or sent over the network.
051   * @throws IOException
052   */
053  void flush() throws IOException;
054}