/*
 * 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.phoenix.monitoring;

import org.apache.phoenix.util.PhoenixStopWatch;

/**
 * Stop watch that is cognizant of the fact whether or not metrics is enabled. If metrics isn't
 * enabled it doesn't do anything. Otherwise, it delegates calls to a {@code PhoenixStopWatch}.
 */
final class MetricsStopWatch {

  private final boolean isMetricsEnabled;
  private final PhoenixStopWatch stopwatch;

  MetricsStopWatch(boolean isMetricsEnabled) {
    this.isMetricsEnabled = isMetricsEnabled;
    this.stopwatch = new PhoenixStopWatch();
  }

  void start() {
    if (isMetricsEnabled) {
      stopwatch.start();
    }
  }

  void stop() {
    if (isMetricsEnabled) {
      if (stopwatch.isRunning()) {
        stopwatch.stop();
      }
    }
  }

  boolean isRunning() {
    return isMetricsEnabled && stopwatch.isRunning();
  }

  long getElapsedTimeInMs() {
    if (isMetricsEnabled) {
      return stopwatch.elapsedMillis();
    }
    return 0;
  }

  @org.apache.phoenix.thirdparty.com.google.common.annotations.VisibleForTesting
  final boolean getMetricsEnabled() {
    return isMetricsEnabled;
  }
}
