io.druid.storage.hdfs.HdfsFileTimestampVersionFinder.java Source code

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Here is the source code for io.druid.storage.hdfs.HdfsFileTimestampVersionFinder.java

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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  Metamarkets 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 io.druid.storage.hdfs;

import com.google.common.base.Throwables;
import com.google.inject.Inject;
import com.metamx.common.RetryUtils;
import io.druid.data.SearchableVersionedDataFinder;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PathFilter;

import java.io.IOException;
import java.net.URI;
import java.util.concurrent.Callable;
import java.util.regex.Pattern;

/**
 * This is implemented explicitly for URIExtractionNamespaceFunctionFactory
 * If you have a use case for this interface beyond URIExtractionNamespaceFunctionFactory please bring it up in the dev list.
 */
public class HdfsFileTimestampVersionFinder extends HdfsDataSegmentPuller
        implements SearchableVersionedDataFinder<URI> {
    @Inject
    public HdfsFileTimestampVersionFinder(Configuration config) {
        super(config);
    }

    private URI mostRecentInDir(final Path dir, final Pattern pattern) throws IOException {
        final PathFilter filter = new PathFilter() {
            @Override
            public boolean accept(Path path) {
                return pattern == null || pattern.matcher(path.getName()).matches();
            }
        };
        long modifiedTime = Long.MIN_VALUE;
        URI mostRecentURI = null;
        final FileSystem fs = dir.getFileSystem(config);
        for (FileStatus status : fs.listStatus(dir, filter)) {
            if (status.isFile()) {
                final long thisModifiedTime = status.getModificationTime();
                if (thisModifiedTime >= modifiedTime) {
                    modifiedTime = thisModifiedTime;
                    mostRecentURI = status.getPath().toUri();
                }
            }
        }

        return mostRecentURI;
    }

    /**
     * Returns the latest modified file at the uri of interest.
     *
     * @param uri     Either a directory or a file on HDFS. If it is a file, the parent directory will be searched.
     * @param pattern A pattern matcher for file names in the directory of interest. Passing `null` results in matching any file in the directory.
     *
     * @return The URI of the file with the most recent modified timestamp.
     */
    @Override
    public URI getLatestVersion(final URI uri, final Pattern pattern) {
        final Path path = new Path(uri);
        try {
            return RetryUtils.retry(new Callable<URI>() {
                @Override
                public URI call() throws Exception {
                    final FileSystem fs = path.getFileSystem(config);
                    if (!fs.exists(path)) {
                        return null;
                    }
                    return mostRecentInDir(fs.isDirectory(path) ? path : path.getParent(), pattern);
                }
            }, shouldRetryPredicate(), DEFAULT_RETRY_COUNT);
        } catch (Exception e) {
            throw Throwables.propagate(e);
        }
    }

    @Override
    public Class<URI> getDataDescriptorClass() {
        return URI.class;
    }
}