| /** |
| * 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.fs; |
| |
| import java.io.FileNotFoundException; |
| import java.io.IOException; |
| import java.util.EnumSet; |
| |
| import org.apache.hadoop.HadoopIllegalArgumentException; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /**************************************************************** |
| * CreateFlag specifies the file create semantic. Users can combine flags like: <br> |
| * <code> |
| * EnumSet.of(CreateFlag.CREATE, CreateFlag.APPEND) |
| * <code> |
| * <p> |
| * |
| * Use the CreateFlag as follows: |
| * <ol> |
| * <li> CREATE - to create a file if it does not exist, |
| * else throw FileAlreadyExists.</li> |
| * <li> APPEND - to append to a file if it exists, |
| * else throw FileNotFoundException.</li> |
| * <li> OVERWRITE - to truncate a file if it exists, |
| * else throw FileNotFoundException.</li> |
| * <li> CREATE|APPEND - to create a file if it does not exist, |
| * else append to an existing file.</li> |
| * <li> CREATE|OVERWRITE - to create a file if it does not exist, |
| * else overwrite an existing file.</li> |
| * </ol> |
| * |
| * Following combination is not valid and will result in |
| * {@link HadoopIllegalArgumentException}: |
| * <ol> |
| * <li> APPEND|OVERWRITE</li> |
| * <li> CREATE|APPEND|OVERWRITE</li> |
| * </ol> |
| *****************************************************************/ |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public enum CreateFlag { |
| |
| /** |
| * Create a file. See javadoc for more description |
| * already exists |
| */ |
| CREATE((short) 0x01), |
| |
| /** |
| * Truncate/overwrite a file. Same as POSIX O_TRUNC. See javadoc for description. |
| */ |
| OVERWRITE((short) 0x02), |
| |
| /** |
| * Append to a file. See javadoc for more description. |
| */ |
| APPEND((short) 0x04); |
| |
| private final short mode; |
| |
| private CreateFlag(short mode) { |
| this.mode = mode; |
| } |
| |
| short getMode() { |
| return mode; |
| } |
| |
| /** |
| * Validate the CreateFlag and throw exception if it is invalid |
| * @param flag set of CreateFlag |
| * @throws HadoopIllegalArgumentException if the CreateFlag is invalid |
| */ |
| public static void validate(EnumSet<CreateFlag> flag) { |
| if (flag == null || flag.isEmpty()) { |
| throw new HadoopIllegalArgumentException(flag |
| + " does not specify any options"); |
| } |
| final boolean append = flag.contains(APPEND); |
| final boolean overwrite = flag.contains(OVERWRITE); |
| |
| // Both append and overwrite is an error |
| if (append && overwrite) { |
| throw new HadoopIllegalArgumentException( |
| flag + "Both append and overwrite options cannot be enabled."); |
| } |
| } |
| |
| /** |
| * Validate the CreateFlag for create operation |
| * @param path Object representing the path; usually String or {@link Path} |
| * @param pathExists pass true if the path exists in the file system |
| * @param flag set of CreateFlag |
| * @throws IOException on error |
| * @throws HadoopIllegalArgumentException if the CreateFlag is invalid |
| */ |
| public static void validate(Object path, boolean pathExists, |
| EnumSet<CreateFlag> flag) throws IOException { |
| validate(flag); |
| final boolean append = flag.contains(APPEND); |
| final boolean overwrite = flag.contains(OVERWRITE); |
| if (pathExists) { |
| if (!(append || overwrite)) { |
| throw new FileAlreadyExistsException("File already exists: " |
| + path.toString() |
| + ". Append or overwrite option must be specified in " + flag); |
| } |
| } else if (!flag.contains(CREATE)) { |
| throw new FileNotFoundException("Non existing file: " + path.toString() |
| + ". Create option is not specified in " + flag); |
| } |
| } |
| } |