| /** |
| * 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.datanode; |
| |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.FileOutputStream; |
| import java.io.IOException; |
| |
| import org.apache.hadoop.hdfs.protocol.Block; |
| import org.apache.hadoop.hdfs.server.datanode.FSDataset.FSVolume; |
| import org.apache.hadoop.fs.FileUtil; |
| import org.apache.hadoop.fs.HardLink; |
| import org.apache.hadoop.io.IOUtils; |
| |
| /** |
| * This class is used by the datanode to maintain the map from a block |
| * to its metadata. |
| */ |
| class DatanodeBlockInfo { |
| |
| private FSVolume volume; // volume where the block belongs |
| private File file; // block file |
| private boolean detached; // copy-on-write done for block |
| |
| DatanodeBlockInfo(FSVolume vol, File file) { |
| this.volume = vol; |
| this.file = file; |
| detached = false; |
| } |
| |
| DatanodeBlockInfo(FSVolume vol) { |
| this.volume = vol; |
| this.file = null; |
| detached = false; |
| } |
| |
| FSVolume getVolume() { |
| return volume; |
| } |
| |
| File getFile() { |
| return file; |
| } |
| |
| /** |
| * Is this block already detached? |
| */ |
| boolean isDetached() { |
| return detached; |
| } |
| |
| /** |
| * Block has been successfully detached |
| */ |
| void setDetached() { |
| detached = true; |
| } |
| |
| /** |
| * Copy specified file into a temporary file. Then rename the |
| * temporary file to the original name. This will cause any |
| * hardlinks to the original file to be removed. The temporary |
| * files are created in the detachDir. The temporary files will |
| * be recovered (especially on Windows) on datanode restart. |
| */ |
| private void detachFile(File file, Block b) throws IOException { |
| File tmpFile = volume.createDetachFile(b, file.getName()); |
| try { |
| IOUtils.copyBytes(new FileInputStream(file), |
| new FileOutputStream(tmpFile), |
| 16*1024, true); |
| if (file.length() != tmpFile.length()) { |
| throw new IOException("Copy of file " + file + " size " + file.length()+ |
| " into file " + tmpFile + |
| " resulted in a size of " + tmpFile.length()); |
| } |
| FileUtil.replaceFile(tmpFile, file); |
| } catch (IOException e) { |
| boolean done = tmpFile.delete(); |
| if (!done) { |
| DataNode.LOG.info("detachFile failed to delete temporary file " + |
| tmpFile); |
| } |
| throw e; |
| } |
| } |
| |
| /** |
| * Returns true if this block was copied, otherwise returns false. |
| */ |
| boolean detachBlock(Block block, int numLinks) throws IOException { |
| if (isDetached()) { |
| return false; |
| } |
| if (file == null || volume == null) { |
| throw new IOException("detachBlock:Block not found. " + block); |
| } |
| File meta = FSDataset.getMetaFile(file, block); |
| if (meta == null) { |
| throw new IOException("Meta file not found for block " + block); |
| } |
| |
| if (HardLink.getLinkCount(file) > numLinks) { |
| DataNode.LOG.info("CopyOnWrite for block " + block); |
| detachFile(file, block); |
| } |
| if (HardLink.getLinkCount(meta) > numLinks) { |
| detachFile(meta, block); |
| } |
| setDetached(); |
| return true; |
| } |
| |
| public String toString() { |
| return getClass().getSimpleName() + "(volume=" + volume |
| + ", file=" + file + ", detached=" + detached + ")"; |
| } |
| } |