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.classification.InterfaceAudience;
24 import org.apache.hadoop.hbase.classification.InterfaceStability;
25 import org.apache.hadoop.hbase.Cell;
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<KeyValue>, 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 }