org.apache.accumulo.server.fs.ViewFSUtils.java Source code

Introduction

Here is the source code for org.apache.accumulo.server.fs.ViewFSUtils.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.accumulo.server.fs;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

/**
 *
 */
public class ViewFSUtils {

    public static final String VIEWFS_CLASSNAME = "org.apache.hadoop.fs.viewfs.ViewFileSystem";

    public static boolean isViewFSSupported() {
        try {
            Class.forName(VIEWFS_CLASSNAME);
            return true;
        } catch (ClassNotFoundException e) {
            return false;
        }
    }

    public static boolean isViewFS(Path source, Configuration conf) throws IOException {
        return isViewFS(source.getFileSystem(conf));
    }

    public static boolean isViewFS(FileSystem fs) {
        return fs.getClass().getName().equals(VIEWFS_CLASSNAME);
    }

    public static Path matchingFileSystem(Path source, String[] options, Configuration conf) throws IOException {

        if (!isViewFS(source, conf))
            throw new IllegalArgumentException("source " + source + " is not view fs");

        String sourceUriPath = source.toUri().getPath();

        Path match = null;
        int matchPrefixLen = 0;

        // find the option with the longest commmon path prefix
        for (String option : options) {
            Path optionPath = new Path(option);
            if (isViewFS(optionPath, conf)) {
                String optionUriPath = optionPath.toUri().getPath();

                int commonPrefixLen = 0;
                for (int i = 0; i < Math.min(sourceUriPath.length(), optionUriPath.length()); i++) {
                    if (sourceUriPath.charAt(i) == optionUriPath.charAt(i)) {
                        if (sourceUriPath.charAt(i) == '/')
                            commonPrefixLen++;
                    } else {
                        break;
                    }
                }

                if (commonPrefixLen > matchPrefixLen) {
                    matchPrefixLen = commonPrefixLen;
                    match = optionPath;
                } else if (match != null && commonPrefixLen == matchPrefixLen
                        && optionPath.depth() < match.depth()) {
                    // take path with less depth when match perfix length is the same
                    match = optionPath;
                }
            }
        }

        return match;
    }

}