azkaban.viewer.hdfs.JsonSequenceFileViewer.java Source code

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Here is the source code for azkaban.viewer.hdfs.JsonSequenceFileViewer.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.PrintWriter;

import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.fs.permission.AccessControlException;
import org.apache.log4j.Logger;

import azkaban.viewer.hdfs.AzkabanSequenceFileReader;

import voldemort.serialization.json.JsonTypeSerializer;

public class JsonSequenceFileViewer extends SequenceFileViewer {
    private static final String VIEWER_NAME = "JSON Sequence File";

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

    private static Logger logger = Logger.getLogger(JsonSequenceFileViewer.class);

    public Set<Capability> getCapabilities(AzkabanSequenceFileReader.Reader reader) {
        Text keySchema = reader.getMetadata().get(new Text("key.schema"));
        Text valueSchema = reader.getMetadata().get(new Text("value.schema"));
        if (keySchema != null && valueSchema != null) {
            return EnumSet.of(Capability.READ);
        }
        return EnumSet.noneOf(Capability.class);
    }

    public void displaySequenceFile(AzkabanSequenceFileReader.Reader reader, PrintWriter output, int startLine,
            int endLine) throws IOException {

        if (logger.isDebugEnabled()) {
            logger.debug("display json file");
        }

        BytesWritable keyWritable = new BytesWritable();
        BytesWritable valueWritable = new BytesWritable();
        Text keySchema = reader.getMetadata().get(new Text("key.schema"));
        Text valueSchema = reader.getMetadata().get(new Text("value.schema"));

        JsonTypeSerializer keySerializer = new JsonTypeSerializer(keySchema.toString());
        JsonTypeSerializer valueSerializer = new JsonTypeSerializer(valueSchema.toString());

        // skip lines before the start line
        for (int i = 1; i < startLine; i++) {
            reader.next(keyWritable, valueWritable);
        }

        // now actually output lines
        for (int i = startLine; i <= endLine; i++) {
            boolean readSomething = reader.next(keyWritable, valueWritable);
            if (!readSomething) {
                break;
            }
            output.write(safeToString(keySerializer.toObject(keyWritable.getBytes())));
            output.write("\t=>\t");
            output.write(safeToString(valueSerializer.toObject(valueWritable.getBytes())));
            output.write("\n");
            output.flush();
        }
    }

    private String safeToString(Object value) {
        if (value == null) {
            return "null";
        } else {
            return value.toString();
        }
    }
}