WatermarkMetadataGenerationCommitStep.java

/*
 * 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 gobblin.data.management.copy.replication;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

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

import com.google.common.base.Charsets;
import com.google.common.base.Objects;

import gobblin.commit.CommitStep;
import gobblin.source.extractor.Watermark;

/**
 * A {@link CommitStep} to write watermark metadata to Hdfs
 * @author mitu
 *
 */
public class WatermarkMetadataGenerationCommitStep implements CommitStep {
  private final String fsUriString;
  private final Path targetDirPath;
  private final Watermark watermark;

  private boolean completed = false;

  public WatermarkMetadataGenerationCommitStep(String fsString, Path targetDirPath, Watermark wm) {
    this.fsUriString = fsString;
    this.targetDirPath = targetDirPath;
    this.watermark = wm;
  }

  @Override
  public boolean isCompleted() throws IOException {
    return this.completed;
  }

  @Override
  public String toString(){
    return Objects.toStringHelper(this.getClass())
        .add("metafile",new Path(this.targetDirPath, ReplicaHadoopFsEndPoint.WATERMARK_FILE))
        .add("file system uri", this.fsUriString)
        .add("watermark class", this.watermark.getClass().getCanonicalName())
        .add("watermark json", this.watermark.toJson().toString())
        .toString();
  }

  @Override
  public void execute() throws IOException {
    URI fsURI;
    try {
      fsURI = new URI(this.fsUriString);
    } catch (URISyntaxException e) {
      throw new IOException("can not build URI " + this.fsUriString, e);
    }
    FileSystem fs = FileSystem.get(fsURI, new Configuration());

    Path filenamePath = new Path(this.targetDirPath, ReplicaHadoopFsEndPoint.WATERMARK_FILE);
    if (fs.exists(filenamePath)) {
      fs.delete(filenamePath, false);
    }

    FSDataOutputStream fout = fs.create(filenamePath);
    fout.write(WatermarkMetadataUtil.serialize(this.watermark).getBytes(Charsets.UTF_8));
    fout.close();
    this.completed = true;
  }

}