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;
  
  import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  /**
   * A {@code StatsLogger} that caches the stats objects created by other {@code StatsLogger}.
   */
  public class CachingStatsLogger implements StatsLogger {
  
      protected final StatsLogger underlying;
      protected final ConcurrentMap<String, Counter> counters;
      protected final ConcurrentMap<String, OpStatsLogger> opStatsLoggers;
      protected final ConcurrentMap<String, StatsLogger> scopeStatsLoggers;
  
      @SuppressFBWarnings("EI_EXPOSE_REP2")
      public CachingStatsLogger(StatsLogger statsLogger) {
          this.underlying = statsLogger;
          this.counters = new ConcurrentHashMap<String, Counter>();
          this.opStatsLoggers = new ConcurrentHashMap<String, OpStatsLogger>();
          this.scopeStatsLoggers = new ConcurrentHashMap<String, StatsLogger>();
      }
  
      @Override
      public int hashCode() {
          return underlying.hashCode();
      }
  
      @Override
      public boolean equals(Object obj) {
          if (!(obj instanceof CachingStatsLogger)) {
              return false;
          }
          CachingStatsLogger another = (CachingStatsLogger) obj;
          return underlying.equals(another.underlying);
      }
  
      @Override
      public String toString() {
          return underlying.toString();
      }
  
      @Override
      public OpStatsLogger getOpStatsLogger(String name) {
          OpStatsLogger opStatsLogger = opStatsLoggers.get(name);
          if (null == opStatsLogger) {
              OpStatsLogger newOpStatsLogger = underlying.getOpStatsLogger(name);
              OpStatsLogger oldOpStatsLogger = opStatsLoggers.putIfAbsent(name, newOpStatsLogger);
              opStatsLogger = (null == oldOpStatsLogger) ? newOpStatsLogger : oldOpStatsLogger;
          }
          return opStatsLogger;
      }
  
      @Override
      public Counter getCounter(String name) {
          Counter counter = counters.get(name);
          if (null == counter) {
              Counter newCounter = underlying.getCounter(name);
              Counter oldCounter = counters.putIfAbsent(name, newCounter);
              counter = (null == oldCounter) ? newCounter : oldCounter;
          }
          return counter;
      }
  
      @Override
      public <T extends Number> void registerGauge(String name, Gauge<T> gauge) {
          underlying.registerGauge(name, gauge);
      }
  
      @Override
      public <T extends Number> void unregisterGauge(String name, Gauge<T> gauge) {
          underlying.unregisterGauge(name, gauge);
      }
  
      @Override
      public StatsLogger scope(String name) {
          StatsLogger statsLogger = scopeStatsLoggers.get(name);
          if (null == statsLogger) {
              StatsLogger newStatsLogger = new CachingStatsLogger(underlying.scope(name));
              StatsLogger oldStatsLogger = scopeStatsLoggers.putIfAbsent(name, newStatsLogger);
              statsLogger = (null == oldStatsLogger) ? newStatsLogger : oldStatsLogger;
          }
          return statsLogger;
      }
  
      @Override
      public void removeScope(String name, StatsLogger statsLogger) {
          scopeStatsLoggers.remove(name, statsLogger);
      }
  
      /**
       Thread-scoped stats not currently supported.
       */
      @Override
      public OpStatsLogger getThreadScopedOpStatsLogger(String name) {
          return getOpStatsLogger(name);
      }
  
      /**
       Thread-scoped stats not currently supported.
       */
      @Override
      public Counter getThreadScopedCounter(String name) {
          return getCounter(name);
      }
  }
  