azkaban.viewer.hdfs.BsonFileViewer.java Source code

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Here is the source code for azkaban.viewer.hdfs.BsonFileViewer.java

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/*
 * Copyright 2012 LinkedIn Corp.
 *
 * Licensed 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 azkaban.viewer.hdfs;

import java.util.EnumSet;
import java.util.Set;
import java.io.IOException;
import java.io.OutputStream;

import org.apache.hadoop.fs.permission.AccessControlException;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import org.bson.BSONObject;
import org.bson.BasicBSONCallback;
import org.bson.BasicBSONDecoder;

import com.mongodb.util.JSON;

/**
 * File viewer for Mongo bson files.
 *
 * @author adilaijaz
 */
public final class BsonFileViewer extends HdfsFileViewer {

    /**
     * The maximum time spent, in milliseconds, while reading records from the
     * file.
     */
    private static long STOP_TIME = 2000l;

    private static final String VIEWER_NAME = "BSON";

    @Override
    public String getName() {
        return VIEWER_NAME;
    }

    @Override
    public Set<Capability> getCapabilities(FileSystem fs, Path path) throws AccessControlException {
        if (path.getName().endsWith(".bson")) {
            return EnumSet.of(Capability.READ);
        }
        return EnumSet.noneOf(Capability.class);
    }

    @Override
    public void displayFile(FileSystem fs, Path path, OutputStream outStream, int startLine, int endLine)
            throws IOException {

        FSDataInputStream in = null;
        try {
            in = fs.open(path, 16 * 1024 * 1024);

            long endTime = System.currentTimeMillis() + STOP_TIME;

            BasicBSONCallback callback = new BasicBSONCallback();
            BasicBSONDecoder decoder = new BasicBSONDecoder();

            /*
             * keep reading and rendering bsonObjects until one of these conditions is
             * met:
             *
             * a. we have rendered all bsonObjects desired. b. we have run out of
             * time.
             */
            for (int lineno = 1; lineno <= endLine && System.currentTimeMillis() <= endTime; lineno++) {
                if (lineno < startLine) {
                    continue;
                }

                callback.reset();
                decoder.decode(in, callback);

                BSONObject value = (BSONObject) callback.get();

                StringBuilder bldr = new StringBuilder();
                bldr.append("\n\n Record ");
                bldr.append(lineno);
                bldr.append('\n');
                JSON.serialize(value, bldr);
                outStream.write(bldr.toString().getBytes("UTF-8"));
            }
        } catch (IOException e) {
            outStream.write(("Error in display avro file: " + e.getLocalizedMessage()).getBytes("UTF-8"));
        } finally {
            if (in != null) {
                in.close();
            }
            outStream.flush();
        }
    }
}