/*
 * 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.metrics;

import org.apache.hadoop.metrics2.MetricsSystem;
import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Metrics {

  private static final Logger LOGGER = LoggerFactory.getLogger(Metrics.class);

  private static volatile MetricsSystem manager = DefaultMetricsSystem.instance();

  private static boolean initialized;

  /** This must match the prefix that we are using in the hadoop-metrics2 config on the client */
  public static final String METRICS_SYSTEM_NAME = "phoenix";

  public static MetricsSystem initialize() {
    // if the jars aren't on the classpath, then we don't start the metrics system
    if (manager == null) {
      LOGGER.warn("Phoenix metrics could not be initialized - no MetricsManager found!");
      return null;
    }
    // only initialize the metrics system once
    synchronized (Metrics.class) {
      if (!initialized) {
        LOGGER.info("Initializing metrics system: " + Metrics.METRICS_SYSTEM_NAME);
        manager.init(Metrics.METRICS_SYSTEM_NAME);
        initialized = true;
      }
    }
    return manager;
  }

  private static volatile boolean sinkInitialized = false;

  /**
   * Mark that the metrics/tracing sink has been initialized
   */
  public static void markSinkInitialized() {
    sinkInitialized = true;
  }

  public static void ensureConfigured() {
    if (!sinkInitialized) {
      LOGGER.warn("Phoenix metrics2/tracing sink was not started. Should be it be?");
    }
  }
}
