/*
    * 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 org.apache.omid.tso;
  
  import org.apache.phoenix.thirdparty.com.google.common.util.concurrent.ThreadFactoryBuilder;
  import com.google.inject.Inject;
  import org.apache.omid.committable.CommitTable;
  import org.apache.omid.metrics.MetricsRegistry;
  import org.apache.omid.metrics.Timer;
  
  import java.io.IOException;
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.Future;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.apache.omid.metrics.MetricsUtils.name;
  
  public class LowWatermarkWriterImpl implements LowWatermarkWriter {
  
      private static final Logger LOG = LoggerFactory.getLogger(LowWatermarkWriterImpl.class);
  
      private final Timer lwmWriteTimer;
      private final CommitTable.Writer lowWatermarkWriter;
      private final ExecutorService lowWatermarkWriterExecutor;
      private MetricsRegistry metrics;
  
      @Inject
      LowWatermarkWriterImpl(TSOServerConfig config,
                             CommitTable commitTable,
                             MetricsRegistry metrics)
              throws Exception {
          this.metrics = metrics;
          this.lowWatermarkWriter = commitTable.getWriter();
          // Low Watermark writer
          ThreadFactoryBuilder lwmThreadFactory = new ThreadFactoryBuilder().setNameFormat("lwm-writer-%d");
          this.lowWatermarkWriterExecutor = Executors.newSingleThreadExecutor(lwmThreadFactory.build());
  
          // Metrics config
          this.lwmWriteTimer = metrics.timer(name("tso", "lwmWriter", "latency"));
          LOG.info("PersistentProcessor initialized");
      }
  
      @Override
      public Future<Void> persistLowWatermark(final long lowWatermark) {
  
          return lowWatermarkWriterExecutor.submit(new Callable<Void>() {
              @Override
              public Void call() throws IOException {
                  try {
                      lwmWriteTimer.start();
                      lowWatermarkWriter.updateLowWatermark(lowWatermark);
                      lowWatermarkWriter.flush();
                  } finally {
                      lwmWriteTimer.stop();
                  }
                  return null;
              }
          });
      }
  }