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.calcite.avatica.metrics.noop;
  
  import org.apache.calcite.avatica.metrics.Counter;
  import org.apache.calcite.avatica.metrics.Gauge;
  import org.apache.calcite.avatica.metrics.Histogram;
  import org.apache.calcite.avatica.metrics.Meter;
  import org.apache.calcite.avatica.metrics.Metric;
  import org.apache.calcite.avatica.metrics.MetricsSystem;
  import org.apache.calcite.avatica.metrics.Timer;
  
  /**
   * {@link MetricsSystem} implementation which does nothing. Returns {@link Metric} implementations
   * which also does nothing (avoiding null instances).
   */
  public class NoopMetricsSystem implements MetricsSystem {
  
    private static final NoopMetricsSystem NOOP_METRICS = new NoopMetricsSystem();
  
    private static final Timer TIMER = new NoopTimer();
    private static final Histogram HISTOGRAM = new NoopHistogram();
    private static final Meter METER = new NoopMeter();
    private static final Counter COUNTER = new NoopCounter();
  
    /**
     * @return A {@link NoopMetricsSystem} instance.
     */
    public static NoopMetricsSystem getInstance() {
      return NOOP_METRICS;
    }
  
    private NoopMetricsSystem() {}
  
    @Override public Timer getTimer(String name) {
      return TIMER;
    }
  
    @Override public Histogram getHistogram(String name) {
      return HISTOGRAM;
    }
  
    @Override public Meter getMeter(String name) {
      return METER;
    }
  
    @Override public Counter getCounter(String name) {
      return COUNTER;
    }
  
    @Override public <T> void register(String name, Gauge<T> gauge) {}
  
  }
  
  // End NoopMetricsSystem.java
  