alluxio.underfs.hdfs.HdfsUnderFileSystemFactory.java Source code

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Here is the source code for alluxio.underfs.hdfs.HdfsUnderFileSystemFactory.java

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/*
 * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
 * (the "License"). You may not use this work except in compliance with the License, which is
 * available at www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied, as more fully set forth in the License.
 *
 * See the NOTICE file distributed with this work for information regarding copyright ownership.
 */

package alluxio.underfs.hdfs;

import alluxio.AlluxioURI;
import alluxio.Configuration;
import alluxio.underfs.UnderFileSystem;
import alluxio.underfs.UnderFileSystemFactory;

import com.google.common.base.Preconditions;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import java.util.HashMap;
import java.util.Map;

import javax.annotation.concurrent.ThreadSafe;

/**
 * Factory for creating {@link HdfsUnderFileSystem}.
 *
 * It caches created {@link HdfsUnderFileSystem}s, using the scheme and authority pair as the key.
 */
@ThreadSafe
public final class HdfsUnderFileSystemFactory implements UnderFileSystemFactory {
    /**
     * Cache mapping {@code Path}s to existing {@link UnderFileSystem} instances. The paths should be
     * normalized to root paths because only their schemes and authorities are needed to identify
     * which {@link FileSystem} they belong to.
     */
    private Map<Path, HdfsUnderFileSystem> mHdfsUfsCache = new HashMap<>();

    /**
     * Constructs a new {@link HdfsUnderFileSystemFactory}.
     */
    public HdfsUnderFileSystemFactory() {
    }

    @Override
    public UnderFileSystem create(String path, Configuration configuration, Object conf) {
        Preconditions.checkArgument(path != null, "path may not be null");

        // Normalize the path to just its root. This is all that's needed to identify which FileSystem
        // the Path belongs to.
        Path rootPath = getRoot(new Path(path));
        synchronized (mHdfsUfsCache) {
            if (!mHdfsUfsCache.containsKey(rootPath)) {
                mHdfsUfsCache.put(rootPath, new HdfsUnderFileSystem(new AlluxioURI(path), configuration, conf));
            }
            return mHdfsUfsCache.get(rootPath);
        }
    }

    private static Path getRoot(Path path) {
        Path currPath = path;
        while (currPath.getParent() != null) {
            currPath = currPath.getParent();
        }
        return currPath;
    }

    @Override
    public boolean supportsPath(String path, Configuration conf) {
        if (path == null) {
            return false;
        }

        return UnderFileSystem.isHadoopUnderFS(path, conf);
    }
}