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.metrics.sink;
  
  import alluxio.metrics.MetricsSystem;
  
  import com.codahale.metrics.ConsoleReporter;
  import com.codahale.metrics.MetricRegistry;
  
  import java.util.Properties;
  import java.util.concurrent.TimeUnit;
  import javax.annotation.concurrent.ThreadSafe;
  
  /**
   * A sink which outputs metric values to the console.
   */
  @ThreadSafe
  public final class ConsoleSink implements Sink {
    private static final int CONSOLE_DEFAULT_PERIOD = 10;
    private static final String CONSOLE_DEFAULT_UNIT = "SECONDS";
  
    private static final String CONSOLE_KEY_PERIOD = "period";
    private static final String CONSOLE_KEY_UNIT = "unit";
  
    private ConsoleReporter mReporter;
    private Properties mProperties;
  
    /**
     * Creates a new {@link ConsoleSink} with a {@link Properties} and {@link MetricRegistry}.
     *
     * @param properties the properties which may contain polling period and unit properties
     * @param registry the metric registry to register
     */
    public ConsoleSink(Properties properties, MetricRegistry registry) {
      mProperties = properties;
      mReporter =
          ConsoleReporter.forRegistry(registry).convertDurationsTo(TimeUnit.MILLISECONDS)
              .convertRatesTo(TimeUnit.SECONDS).build();
      MetricsSystem.checkMinimalPollingPeriod(getPollUnit(), getPollPeriod());
    }
  
    @Override
    public void start() {
      mReporter.start(getPollPeriod(), getPollUnit());
    }
  
    @Override
    public void stop() {
      mReporter.stop();
    }
  
    @Override
    public void report() {
      mReporter.report();
    }
  
    /**
     * Gets the polling period.
     *
     * @return the polling period set by properties. If it is not set, a default value 10 is
     *         returned.
     */
    private int getPollPeriod() {
      String period = mProperties.getProperty(CONSOLE_KEY_PERIOD);
      return period != null ? Integer.parseInt(period) : CONSOLE_DEFAULT_PERIOD;
    }
  
    /**
     * Gets the polling time unit.
     *
     * @return the polling time unit set by properties, If it is not set, a default value SECONDS is
     *         returned.
     */
    private TimeUnit getPollUnit() {
      String unit = mProperties.getProperty(CONSOLE_KEY_UNIT);
      if (unit == null) {
        unit = CONSOLE_DEFAULT_UNIT;
      }
      return TimeUnit.valueOf(unit.toUpperCase());
    }
  }
  