org.apache.hadoop.hdfs.server.blockmanagement.ContiguousBlockStorageOp.java Source code

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Here is the source code for org.apache.hadoop.hdfs.server.blockmanagement.ContiguousBlockStorageOp.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hdfs.server.blockmanagement;

import com.google.common.base.Preconditions;

/**
 * Utility class with logic on managing storage locations shared between
 * complete and under-construction blocks under the contiguous format --
 * {@link BlockInfoContiguous} and
 * {@link BlockInfoUnderConstructionContiguous}.
 */
class ContiguousBlockStorageOp {
    /**
     * Ensure that there is enough  space to include num more triplets.
     * @return first free triplet index.
     */
    private static int ensureCapacity(BlockInfo b, int num) {
        Preconditions.checkArgument(b.triplets != null, "BlockInfo is not initialized");
        int last = b.numNodes();
        if (b.triplets.length >= (last + num) * 3) {
            return last;
        }
        /* Not enough space left. Create a new array. Should normally
         * happen only when replication is manually increased by the user. */
        Object[] old = b.triplets;
        b.triplets = new Object[(last + num) * 3];
        System.arraycopy(old, 0, b.triplets, 0, last * 3);
        return last;
    }

    static boolean addStorage(BlockInfo b, DatanodeStorageInfo storage) {
        // find the last null node
        int lastNode = ensureCapacity(b, 1);
        b.setStorageInfo(lastNode, storage);
        b.setNext(lastNode, null);
        b.setPrevious(lastNode, null);
        return true;
    }

    static boolean removeStorage(BlockInfo b, DatanodeStorageInfo storage) {
        int dnIndex = b.findStorageInfo(storage);
        if (dnIndex < 0) { // the node is not found
            return false;
        }
        Preconditions.checkArgument(b.getPrevious(dnIndex) == null && b.getNext(dnIndex) == null,
                "Block is still in the list and must be removed first.");
        // find the last not null node
        int lastNode = b.numNodes() - 1;
        // replace current node triplet by the lastNode one
        b.setStorageInfo(dnIndex, b.getStorageInfo(lastNode));
        b.setNext(dnIndex, b.getNext(lastNode));
        b.setPrevious(dnIndex, b.getPrevious(lastNode));
        // set the last triplet to null
        b.setStorageInfo(lastNode, null);
        b.setNext(lastNode, null);
        b.setPrevious(lastNode, null);
        return true;
    }

    static int numNodes(BlockInfo b) {
        Preconditions.checkArgument(b.triplets != null, "BlockInfo is not initialized");
        Preconditions.checkArgument(b.triplets.length % 3 == 0, "Malformed BlockInfo");

        for (int idx = b.getCapacity() - 1; idx >= 0; idx--) {
            if (b.getDatanode(idx) != null) {
                return idx + 1;
            }
        }
        return 0;
    }

    static void replaceBlock(BlockInfo b, BlockInfo newBlock) {
        for (int i = b.numNodes() - 1; i >= 0; i--) {
            final DatanodeStorageInfo storage = b.getStorageInfo(i);
            final boolean removed = storage.removeBlock(b);
            Preconditions.checkState(removed, "currentBlock not found.");

            final DatanodeStorageInfo.AddBlockResult result = storage.addBlock(newBlock);
            Preconditions.checkState(result == DatanodeStorageInfo.AddBlockResult.ADDED,
                    "newBlock already exists.");
        }
    }
}