/*
 * 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;

/**
 * Version of {@link Metric} that can be used when the metric isn't getting concurrently
 * modified/accessed by multiple threads and the memory consistency effects of happen-before can be
 * established. For example - phoenix client side metrics are modified/accessed by only one thread
 * at a time. Further, the actions of threads in the phoenix client thread pool happen-before the
 * actions of the thread that performs the aggregation of metrics. This makes
 * {@link NonAtomicMetric} a good fit for storing Phoenix's client side request level metrics.
 */
class NonAtomicMetric implements Metric {

  private final MetricType type;
  private long value;

  public NonAtomicMetric(MetricType type) {
    this.type = type;
  }

  @Override
  public MetricType getMetricType() {
    return type;
  }

  @Override
  public long getValue() {
    return value;
  }

  @Override
  public void change(long delta) {
    value += delta;
  }

  @Override
  public void increment() {
    value++;
  }

  @Override
  public String getCurrentMetricState() {
    return type.shortName() + ": " + value;
  }

  @Override
  public void reset() {
    value = 0;
  }

  /**
   * Set the Metric value as current value
   */
  @Override
  public void set(long value) {
    this.value = value;
  }

  @Override
  public void decrement() {
    value--;
  }

}
