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.TimeUnit;
  
  /**
   * A <i>no-op</i> {@code StatsLogger}.
   *
   * <p>Metrics are not recorded, making this receiver useful in unit tests and as defaults in
   * situations where metrics are not strictly required.
   */
  @SuppressFBWarnings("EI_EXPOSE_REP2")
  public class NullStatsLogger implements StatsLogger {
  
      public static final NullStatsLogger INSTANCE = new NullStatsLogger();
  
      /**
       * A <i>no-op</i> {@code OpStatsLogger}.
       */
      static class NullOpStatsLogger implements OpStatsLogger {
          final OpStatsData nullOpStats = new OpStatsData(0, 0, 0, new long[6]);
  
          @Override
          public void registerFailedEvent(long eventLatency, TimeUnit unit) {
              // nop
          }
  
          @Override
          public void registerSuccessfulEvent(long eventLatency, TimeUnit unit) {
              // nop
          }
  
          @Override
          public void registerSuccessfulValue(long value) {
              // nop
          }
  
          @Override
          public void registerFailedValue(long value) {
              // nop
          }
  
          @Override
          public OpStatsData toOpStatsData() {
              return nullOpStats;
          }
  
          @Override
          public void clear() {
              // nop
          }
      }
      static NullOpStatsLogger nullOpStatsLogger = new NullOpStatsLogger();
  
      /**
       * A <i>no-op</i> {@code Counter}.
       */
      static class NullCounter implements Counter {
          @Override
          public void clear() {
              // nop
          }
  
          @Override
          public void inc() {
              // nop
          }
  
          @Override
          public void dec() {
              // nop
          }
  
          @Override
          public void addCount(long delta) {
              // nop
          }
  
          @Override
          public void addLatency(long eventLatency, TimeUnit unit) {
              // nop
          }
  
          @Override
          public Long get() {
              return 0L;
          }
      }
      static NullCounter nullCounter = new NullCounter();
  
      @Override
      public OpStatsLogger getOpStatsLogger(String name) {
          return nullOpStatsLogger;
      }
  
      @Override
      public Counter getCounter(String name) {
          return nullCounter;
      }
  
      @Override
      public <T extends Number> void registerGauge(String name, Gauge<T> gauge) {
          // nop
      }
  
      @Override
      public <T extends Number> void unregisterGauge(String name, Gauge<T> gauge) {
          // nop
      }
  
      @Override
      public StatsLogger scope(String name) {
          return this;
      }
  
      @Override
      public void removeScope(String name, StatsLogger statsLogger) {
          // nop
      }
  
      @Override
      public OpStatsLogger getThreadScopedOpStatsLogger(String name) {
          return getOpStatsLogger(name);
      }
  
      @Override
      public Counter getThreadScopedCounter(String name) {
          return getCounter(name);
      }
  }
  