content: /*
   * 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.bookkeeper.stats.prometheus;
  
  import java.util.Map;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.LongAdder;
  import org.apache.bookkeeper.stats.Counter;
  
  /**
   * {@link Counter} implementation based on {@link LongAdder}.
   *
   * <p>LongAdder keeps a counter per-thread and then aggregates to get the result, in order to avoid contention between
   * multiple threads.
   */
  public class LongAdderCounter implements Counter {
      private final LongAdder counter = new LongAdder();
  
      private Map<String, String> labels;
  
      // used for lazy registration for thread scoped metric
      private boolean threadInitialized;
  
      public LongAdderCounter(Map<String, String> labels) {
          this.labels = labels;
      }
  
      @Override
      public void clear() {
          counter.reset();
      }
  
      @Override
      public void inc() {
          counter.increment();
      }
  
      @Override
      public void dec() {
          counter.decrement();
      }
  
      @Override
      public void addCount(long delta) {
          counter.add(delta);
      }
  
      /**
       * When counter is used to count time.
       * consistent with the {@link DataSketchesOpStatsLogger#registerSuccessfulEvent(long, TimeUnit)} 's logic
       * */
      @Override
      public void addLatency(long eventLatency, TimeUnit unit) {
          long valueMillis = unit.toMillis(eventLatency);
          counter.add(valueMillis);
      }
  
      @Override
      public Long get() {
          return counter.sum();
      }
  
      public Map<String, String> getLabels() {
          return labels;
      }
  
      public boolean isThreadInitialized() {
          return threadInitialized;
      }
  
      public void initializeThread(Map<String, String> labels) {
          this.labels = labels;
          this.threadInitialized = true;
      }
  }
  