| /** |
| * 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.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.hdfs.protocol.Block; |
| |
| /** Provide utility methods for Datanode. */ |
| @InterfaceAudience.Private |
| class DatanodeUtil { |
| 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; |
| } |
| } |