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.codec; 20 21 import java.io.IOException; 22 23 import org.apache.hadoop.classification.InterfaceAudience; 24 import org.apache.hadoop.classification.InterfaceStability; 25 import org.apache.hadoop.hbase.KeyValue; 26 27 /** 28 * Accepts a stream of KeyValues. This can be used to anywhere KeyValues need to be written out, but 29 * currently it is only used for serializing WALEdits. This could be backed by a List<KeyValue>, but 30 * more efficient implementations will append results to a byte[] to eliminate overhead, and 31 * possibly encode the underlying data further. 32 * <p> 33 * To read the data back, use a corresponding {@link Decoder} 34 * @see Decoder 35 */ 36 @InterfaceAudience.Private 37 @InterfaceStability.Evolving 38 public interface Encoder { 39 /** 40 * Implementation must copy the entire state of the cell. If the written cell is modified 41 * immediately after the write method returns, the modifications must have absolutely no effect on 42 * the copy of the cell that was added in the write. 43 * @param cell cell to serialize 44 * @throws IOException 45 */ 46 void write(KeyValue cell) throws IOException; 47 48 /** 49 * Let the implementation decide what to do. Usually means writing accumulated data into a 50 * byte[] that can then be read from the implementation to be sent to disk, put in the block 51 * cache, or sent over the network. 52 * @throws IOException 53 */ 54 void flush() throws IOException; 55 }