| /** |
| * 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 java.util.Iterator; |
| |
| import org.apache.hadoop.hdfs.protocol.Block; |
| import org.apache.hadoop.hdfs.util.GSet; |
| import org.apache.hadoop.hdfs.util.LightWeightGSet; |
| |
| /** |
| * This class maintains the map from a block to its metadata. |
| * block's metadata currently includes blockCollection it belongs to and |
| * the datanodes that store the block. |
| */ |
| class BlocksMap { |
| private static class NodeIterator implements Iterator<DatanodeDescriptor> { |
| private BlockInfo blockInfo; |
| private int nextIdx = 0; |
| |
| NodeIterator(BlockInfo blkInfo) { |
| this.blockInfo = blkInfo; |
| } |
| |
| @Override |
| public boolean hasNext() { |
| return blockInfo != null && nextIdx < blockInfo.getCapacity() |
| && blockInfo.getDatanode(nextIdx) != null; |
| } |
| |
| @Override |
| public DatanodeDescriptor next() { |
| return blockInfo.getDatanode(nextIdx++); |
| } |
| |
| @Override |
| public void remove() { |
| throw new UnsupportedOperationException("Sorry. can't remove."); |
| } |
| } |
| |
| /** Constant {@link LightWeightGSet} capacity. */ |
| private final int capacity; |
| |
| private GSet<Block, BlockInfo> blocks; |
| |
| BlocksMap(final float loadFactor) { |
| this.capacity = computeCapacity(); |
| this.blocks = new LightWeightGSet<Block, BlockInfo>(capacity); |
| } |
| |
| /** |
| * Let t = 2% of max memory. |
| * Let e = round(log_2 t). |
| * Then, we choose capacity = 2^e/(size of reference), |
| * unless it is outside the close interval [1, 2^30]. |
| */ |
| private static int computeCapacity() { |
| //VM detection |
| //See http://java.sun.com/docs/hotspot/HotSpotFAQ.html#64bit_detection |
| final String vmBit = System.getProperty("sun.arch.data.model"); |
| |
| //2% of max memory |
| final double twoPC = Runtime.getRuntime().maxMemory()/50.0; |
| |
| //compute capacity |
| final int e1 = (int)(Math.log(twoPC)/Math.log(2.0) + 0.5); |
| final int e2 = e1 - ("32".equals(vmBit)? 2: 3); |
| final int exponent = e2 < 0? 0: e2 > 30? 30: e2; |
| final int c = 1 << exponent; |
| |
| if (LightWeightGSet.LOG.isDebugEnabled()) { |
| LightWeightGSet.LOG.debug("VM type = " + vmBit + "-bit"); |
| LightWeightGSet.LOG.debug("2% max memory = " + twoPC/(1 << 20) + " MB"); |
| LightWeightGSet.LOG.debug("capacity = 2^" + exponent |
| + " = " + c + " entries"); |
| } |
| return c; |
| } |
| |
| void close() { |
| // Empty blocks once GSet#clear is implemented (HDFS-3940) |
| } |
| |
| BlockCollection getBlockCollection(Block b) { |
| BlockInfo info = blocks.get(b); |
| return (info != null) ? info.getBlockCollection() : null; |
| } |
| |
| /** |
| * Add block b belonging to the specified block collection to the map. |
| */ |
| BlockInfo addBlockCollection(BlockInfo b, BlockCollection bc) { |
| BlockInfo info = blocks.get(b); |
| if (info != b) { |
| info = b; |
| blocks.put(info); |
| } |
| info.setBlockCollection(bc); |
| return info; |
| } |
| |
| /** |
| * Remove the block from the block map; |
| * remove it from all data-node lists it belongs to; |
| * and remove all data-node locations associated with the block. |
| */ |
| void removeBlock(Block block) { |
| BlockInfo blockInfo = blocks.remove(block); |
| if (blockInfo == null) |
| return; |
| |
| blockInfo.setBlockCollection(null); |
| for(int idx = blockInfo.numNodes()-1; idx >= 0; idx--) { |
| DatanodeDescriptor dn = blockInfo.getDatanode(idx); |
| dn.removeBlock(blockInfo); // remove from the list and wipe the location |
| } |
| } |
| |
| /** Returns the block object it it exists in the map. */ |
| BlockInfo getStoredBlock(Block b) { |
| return blocks.get(b); |
| } |
| |
| /** |
| * Searches for the block in the BlocksMap and |
| * returns Iterator that iterates through the nodes the block belongs to. |
| */ |
| Iterator<DatanodeDescriptor> nodeIterator(Block b) { |
| return nodeIterator(blocks.get(b)); |
| } |
| |
| /** |
| * For a block that has already been retrieved from the BlocksMap |
| * returns Iterator that iterates through the nodes the block belongs to. |
| */ |
| Iterator<DatanodeDescriptor> nodeIterator(BlockInfo storedBlock) { |
| return new NodeIterator(storedBlock); |
| } |
| |
| /** counts number of containing nodes. Better than using iterator. */ |
| int numNodes(Block b) { |
| BlockInfo info = blocks.get(b); |
| return info == null ? 0 : info.numNodes(); |
| } |
| |
| /** |
| * Remove data-node reference from the block. |
| * Remove the block from the block map |
| * only if it does not belong to any file and data-nodes. |
| */ |
| boolean removeNode(Block b, DatanodeDescriptor node) { |
| BlockInfo info = blocks.get(b); |
| if (info == null) |
| return false; |
| |
| // remove block from the data-node list and the node from the block info |
| boolean removed = node.removeBlock(info); |
| |
| if (info.getDatanode(0) == null // no datanodes left |
| && info.getBlockCollection() == null) { // does not belong to a file |
| blocks.remove(b); // remove block from the map |
| } |
| return removed; |
| } |
| |
| int size() { |
| return blocks.size(); |
| } |
| |
| Iterable<BlockInfo> getBlocks() { |
| return blocks; |
| } |
| |
| /** Get the capacity of the HashMap that stores blocks */ |
| int getCapacity() { |
| return capacity; |
| } |
| |
| /** |
| * Replace a block in the block map by a new block. |
| * The new block and the old one have the same key. |
| * @param newBlock - block for replacement |
| * @return new block |
| */ |
| BlockInfo replaceBlock(BlockInfo newBlock) { |
| BlockInfo currentBlock = blocks.get(newBlock); |
| assert currentBlock != null : "the block if not in blocksMap"; |
| // replace block in data-node lists |
| for(int idx = currentBlock.numNodes()-1; idx >= 0; idx--) { |
| DatanodeDescriptor dn = currentBlock.getDatanode(idx); |
| dn.replaceBlock(currentBlock, newBlock); |
| } |
| // replace block in the map itself |
| blocks.put(newBlock); |
| return newBlock; |
| } |
| } |