org.apache.hadoop.hdfs.protocol.LayoutFlags.java Source code

Introduction

Here is the source code for org.apache.hadoop.hdfs.protocol.LayoutFlags.java

Source

/**
 * 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.protocol;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import org.apache.hadoop.classification.InterfaceAudience;

import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;

/**
 * LayoutFlags represent features which the FSImage and edit logs can either
 * support or not, independently of layout version.
 * 
 * Note: all flags starting with 'test' are reserved for unit test purposes.
 */
@InterfaceAudience.Private
public class LayoutFlags {
    /**
     * Load a LayoutFlags object from a stream.
     *
     * @param in            The stream to read from.
     * @throws IOException
     */
    public static LayoutFlags read(DataInputStream in) throws IOException {
        int length = in.readInt();
        if (length < 0) {
            throw new IOException(
                    "The length of the feature flag section " + "was negative at " + length + " bytes.");
        } else if (length > 0) {
            throw new IOException("Found feature flags which we can't handle. " + "Please upgrade your software.");
        }
        return new LayoutFlags();
    }

    private LayoutFlags() {
    }

    public static void write(DataOutputStream out) throws IOException {
        out.writeInt(0);
    }
}