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    package org.apache.hadoop.hdfs.server.blockmanagement;
019    
020    import java.io.IOException;
021    
022    /** 
023     * This interface is used by the block manager to expose a
024     * few characteristics of a collection of Block/BlockUnderConstruction.
025     */
026    public interface MutableBlockCollection extends BlockCollection {
027      /**
028       * Set the block at the given index.
029       */
030      public void setBlock(int index, BlockInfo blk);
031    
032      /**
033       * Convert the last block of the collection to an under-construction block
034       * and set the locations.
035       */
036      public BlockInfoUnderConstruction setLastBlock(BlockInfo lastBlock,
037          DatanodeStorageInfo[] storages) throws IOException;
038    }