/**
 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.hadoop.ozone.om.ratis.metrics;

import org.apache.hadoop.metrics2.MetricsSystem;
import org.apache.hadoop.metrics2.annotation.Metric;
import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
import org.apache.hadoop.metrics2.lib.MutableCounterLong;

/**
 * Class which maintains metrics related to OzoneManager DoubleBuffer.
 */
public class OzoneManagerDoubleBufferMetrics {

  private static final String SOURCE_NAME =
      OzoneManagerDoubleBufferMetrics.class.getSimpleName();

  @Metric(about = "Total Number of flush operations happened in " +
      "OzoneManagerDoubleBuffer.")
  private MutableCounterLong totalNumOfFlushOperations;

  @Metric(about = "Total Number of flushed transactions happened in " +
      "OzoneManagerDoubleBuffer.")
  private MutableCounterLong totalNumOfFlushedTransactions;

  @Metric(about = "Max Number of transactions flushed in a iteration in " +
      "OzoneManagerDoubleBuffer. This will provide a value which is maximum " +
      "number of transactions flushed in a single flush iteration till now.")
  private MutableCounterLong maxNumberOfTransactionsFlushedInOneIteration;


  public static OzoneManagerDoubleBufferMetrics create() {
    MetricsSystem ms = DefaultMetricsSystem.instance();
    return ms.register(SOURCE_NAME,
        "OzoneManager DoubleBuffer Metrics",
        new OzoneManagerDoubleBufferMetrics());
  }

  public void incrTotalNumOfFlushOperations() {
    this.totalNumOfFlushOperations.incr();
  }

  public void incrTotalSizeOfFlushedTransactions(
      long flushedTransactions) {
    this.totalNumOfFlushedTransactions.incr(flushedTransactions);
  }

  public void setMaxNumberOfTransactionsFlushedInOneIteration(
      long maxTransactions) {
    // We should set the value with maxTransactions, so decrement old value
    // first and then add the new value.
    this.maxNumberOfTransactionsFlushedInOneIteration.incr(
        Math.negateExact(getMaxNumberOfTransactionsFlushedInOneIteration())
            + maxTransactions);
  }

  public long getTotalNumOfFlushOperations() {
    return totalNumOfFlushOperations.value();
  }

  public long getTotalNumOfFlushedTransactions() {
    return totalNumOfFlushedTransactions.value();
  }

  public long getMaxNumberOfTransactionsFlushedInOneIteration() {
    return maxNumberOfTransactionsFlushedInOneIteration.value();
  }

  public void unRegister() {
    MetricsSystem ms = DefaultMetricsSystem.instance();
    ms.unregisterSource(SOURCE_NAME);
  }
}