| /** |
| * 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.FilenameFilter; |
| import java.io.IOException; |
| import java.util.Arrays; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.hdfs.protocol.Block; |
| |
| /** Provide utility methods for Datanode. */ |
| @InterfaceAudience.Private |
| class DatanodeUtil { |
| static final String METADATA_EXTENSION = ".meta"; |
| |
| static final String UNLINK_BLOCK_SUFFIX = ".unlinked"; |
| |
| private final static String DISK_ERROR = "Possible disk error on file creation: "; |
| |
| /** Get the cause of an I/O exception if caused by a possible disk error |
| * @param ioe an I/O exception |
| * @return cause if the I/O exception is caused by a possible disk error; |
| * null otherwise. |
| */ |
| static IOException getCauseIfDiskError(IOException ioe) { |
| if (ioe.getMessage()!=null && ioe.getMessage().startsWith(DISK_ERROR)) { |
| return (IOException)ioe.getCause(); |
| } else { |
| return null; |
| } |
| } |
| |
| /** |
| * Create a new file. |
| * @throws IOException |
| * if the file already exists or if the file cannot be created. |
| */ |
| static File createTmpFile(Block b, File f) throws IOException { |
| if (f.exists()) { |
| throw new IOException("Unexpected problem in creating temporary file for " |
| + b + ". File " + f + " should not be present, but is."); |
| } |
| // Create the zero-length temp file |
| final boolean fileCreated; |
| try { |
| fileCreated = f.createNewFile(); |
| } catch (IOException ioe) { |
| throw (IOException)new IOException(DISK_ERROR + f).initCause(ioe); |
| } |
| if (!fileCreated) { |
| throw new IOException("Unexpected problem in creating temporary file for " |
| + b + ". File " + f + " should be creatable, but is already present."); |
| } |
| return f; |
| } |
| |
| static String getMetaFileName(String blockFileName, long genStamp) { |
| return blockFileName + "_" + genStamp + METADATA_EXTENSION; |
| } |
| |
| static File getMetaFile(File f, long genStamp) { |
| return new File(getMetaFileName(f.getAbsolutePath(), genStamp)); |
| } |
| |
| /** Find the corresponding meta data file from a given block file */ |
| static File findMetaFile(final File blockFile) throws IOException { |
| final String prefix = blockFile.getName() + "_"; |
| final File parent = blockFile.getParentFile(); |
| File[] matches = parent.listFiles(new FilenameFilter() { |
| public boolean accept(File dir, String name) { |
| return dir.equals(parent) |
| && name.startsWith(prefix) && name.endsWith(METADATA_EXTENSION); |
| } |
| }); |
| |
| if (matches == null || matches.length == 0) { |
| throw new IOException("Meta file not found, blockFile=" + blockFile); |
| } |
| else if (matches.length > 1) { |
| throw new IOException("Found more than one meta files: " |
| + Arrays.asList(matches)); |
| } |
| return matches[0]; |
| } |
| |
| static File getUnlinkTmpFile(File f) { |
| return new File(f.getParentFile(), f.getName()+UNLINK_BLOCK_SUFFIX); |
| } |
| } |