hbase-common/src/main/java/org/apache/hadoop/hbase/io/CellOutputStream.java

   1 /*
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18
  19 package org.apache.hadoop.hbase.io;
  20
  21 import java.io.IOException;
  22
  23 import org.apache.hadoop.hbase.Cell;
  24 import org.apache.yetus.audience.InterfaceAudience;
  25 import org.apache.yetus.audience.InterfaceStability;
  26
  27 /**
  28  * Accepts a stream of Cells. This can be used to build a block of cells during compactions
  29  * and flushes, or to build a byte[] to send to the client. This could be backed by a
  30  * List&lt;KeyValue&gt;, but more efficient implementations will append results to a
  31  * byte[] to eliminate overhead, and possibly encode the cells further.
  32  * <p>To read Cells, use {@link org.apache.hadoop.hbase.CellScanner}
  33  * @see org.apache.hadoop.hbase.CellScanner
  34  */
  35 @InterfaceAudience.Private
  36 @InterfaceStability.Evolving
  37 public interface CellOutputStream {
  38   /**
  39    * Implementation must copy the entire state of the Cell. If the written Cell is modified
  40    * immediately after the write method returns, the modifications must have absolutely no effect
  41    * on the copy of the Cell that was added in the write.
  42    * @param cell Cell to write out
  43    * @throws IOException
  44    */
  45   void write(Cell cell) throws IOException;
  46
  47   /**
  48    * Let the implementation decide what to do.  Usually means writing accumulated data into a
  49    * byte[] that can then be read from the implementation to be sent to disk, put in the block
  50    * cache, or sent over the network.
  51    * @throws IOException
  52    */
  53   void flush() throws IOException;
  54 }