content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.master.service.jvmmonitor;
  
  import alluxio.conf.Configuration;
  import alluxio.conf.PropertyKey;
  import alluxio.master.service.NoopService;
  import alluxio.master.service.SimpleService;
  import alluxio.metrics.MetricKey;
  import alluxio.metrics.MetricsSystem;
  import alluxio.util.JvmPauseMonitor;
  
  import com.google.common.base.Preconditions;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.annotation.Nullable;
  import javax.annotation.concurrent.GuardedBy;
  
  /**
   * Created by {@link JvmMonitorService.Factory}.
   * This service creates and starts a {@link JvmPauseMonitor} upon being started and stops said
   * pause monitor upon being stopped.
   */
  public class JvmMonitorService implements SimpleService {
    protected static final Logger LOG = LoggerFactory.getLogger(JvmMonitorService.class);
  
    @Nullable @GuardedBy("this")
    private JvmPauseMonitor mJvmPauseMonitor = null;
  
    private JvmMonitorService() {}
  
    @Override
    public synchronized void start() {
      LOG.info("Starting {}", this.getClass().getSimpleName());
      Preconditions.checkState(mJvmPauseMonitor == null, "JVM pause monitor must not already exist");
      mJvmPauseMonitor = new JvmPauseMonitor(
          Configuration.getMs(PropertyKey.JVM_MONITOR_SLEEP_INTERVAL_MS),
          Configuration.getMs(PropertyKey.JVM_MONITOR_WARN_THRESHOLD_MS),
          Configuration.getMs(PropertyKey.JVM_MONITOR_INFO_THRESHOLD_MS));
      mJvmPauseMonitor.start();
      MetricsSystem.registerGaugeIfAbsent(
          MetricsSystem.getMetricName(MetricKey.TOTAL_EXTRA_TIME.getName()),
          mJvmPauseMonitor::getTotalExtraTime);
      MetricsSystem.registerGaugeIfAbsent(
          MetricsSystem.getMetricName(MetricKey.INFO_TIME_EXCEEDED.getName()),
          mJvmPauseMonitor::getInfoTimeExceeded);
      MetricsSystem.registerGaugeIfAbsent(
          MetricsSystem.getMetricName(MetricKey.WARN_TIME_EXCEEDED.getName()),
          mJvmPauseMonitor::getWarnTimeExceeded);
    }
  
    @Override
    public synchronized void promote() {}
  
    @Override
    public synchronized void demote() {}
  
    @Override
    public synchronized void stop() {
      LOG.info("Stopping {}", this.getClass().getSimpleName());
      if (mJvmPauseMonitor != null) {
        mJvmPauseMonitor.stop();
        mJvmPauseMonitor = null;
      }
    }
  
    /**
     * Factory that returns the appropriate {@link JvmMonitorService} based on configuration.
     */
    public static class Factory {
      /**
       * @return a simple service that manages the behavior of the {@link JvmPauseMonitor}
       */
      public static SimpleService create() {
        if (!Configuration.getBoolean(PropertyKey.MASTER_JVM_MONITOR_ENABLED)) {
          return new NoopService();
        }
        return new JvmMonitorService();
      }
    }
  }
  