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.cassandra.distributed.impl;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.function.Predicate;
  
  import com.codahale.metrics.Counting;
  import com.codahale.metrics.Gauge;
  import com.codahale.metrics.Histogram;
  import com.codahale.metrics.Meter;
  import com.codahale.metrics.Metric;
  import com.codahale.metrics.Snapshot;
  import com.codahale.metrics.Timer;
  import org.apache.cassandra.distributed.shared.Metrics;
  import org.apache.cassandra.metrics.CassandraMetricsRegistry;
  
  /**
   * Pulls metrics out of in-JVM dtest cluster instance.
   */
  class InstanceMetrics implements Metrics
  {
      private final CassandraMetricsRegistry metricsRegistry;
  
      InstanceMetrics(CassandraMetricsRegistry metricsRegistry)
      {
          this.metricsRegistry = metricsRegistry;
      }
  
      @Override
      public List<String> getNames()
      {
          return new ArrayList<>(metricsRegistry.getNames());
      }
  
      @Override
      public long getCounter(String name)
      {
          Metric metric = metricsRegistry.getMetrics().get(name);
          if (metric instanceof Counting)
              return ((Counting) metric).getCount();
          // If the metric is not found or does not expose a getCount method
          return 0;
      }
  
      @Override
      public Map<String, Long> getCounters(Predicate<String> filter)
      {
          Map<String, Long> values = new HashMap<>();
          for (Map.Entry<String, Metric> e : metricsRegistry.getMetrics().entrySet())
          {
              Metric metric = e.getValue();
              if (metric instanceof Counting && filter.test(e.getKey()))
                  values.put(e.getKey(), ((Counting) metric).getCount());
          }
          return values;
      }
  
      @Override
      public double getHistogram(String name, MetricValue value)
      {
          Histogram histogram = metricsRegistry.getHistograms().get(name);
          return getValue(histogram, value);
      }
  
      @Override
      public Map<String, Double> getHistograms(Predicate<String> filter, MetricValue value)
      {
          Map<String, Double> values = new HashMap<>();
          for (Map.Entry<String, Histogram> e : metricsRegistry.getHistograms().entrySet())
          {
              if (filter.test(e.getKey()))
                  values.put(e.getKey(), getValue(e.getValue(), value));
          }
          return values;
      }
  
      @Override
      public Object getGauge(String name)
      {
          return metricsRegistry.getGauges().get(name).getValue();
      }
  
      @Override
      public Map<String, Object> getGauges(Predicate<String> filter)
      {
          Map<String, Object> values = new HashMap<>();
          for (Map.Entry<String, Gauge> e : metricsRegistry.getGauges().entrySet())
          {
              if (filter.test(e.getKey()))
                  values.put(e.getKey(), e.getValue().getValue());
          }
          return values;
      }
  
      @Override
      public double getMeter(String name, Rate value)
      {
          return getRate(metricsRegistry.getMeters().get(name), value);
      }
  
      @Override
      public Map<String, Double> getMeters(Predicate<String> filter, Rate rate)
      {
          Map<String, Double> values = new HashMap<>();
          for (Map.Entry<String, Meter> e : metricsRegistry.getMeters().entrySet())
          {
              if (filter.test(e.getKey()))
                  values.put(e.getKey(), getRate(e.getValue(), rate));
          }
          return values;
      }
  
      @Override
      public double getTimer(String name, MetricValue value)
      {
          return getValue(metricsRegistry.getTimers().get(name).getSnapshot(), value);
      }
  
      @Override
      public Map<String, Double> getTimers(Predicate<String> filter, MetricValue value)
      {
          Map<String, Double> values = new HashMap<>();
          for (Map.Entry<String, Timer> e : metricsRegistry.getTimers().entrySet())
          {
              if (filter.test(e.getKey()))
                  values.put(e.getKey(), getValue(e.getValue().getSnapshot(), value));
          }
  
          return values;
      }
  
      static double getValue(Histogram histogram, MetricValue value)
      {
          if (value == MetricValue.COUNT)
              return histogram.getCount();
  
          return getValue(histogram.getSnapshot(), value);
      }
  
      static double getValue(Snapshot snapshot, MetricValue value)
      {
          switch (value)
          {
              case MEDIAN:
                  return snapshot.getMedian();
              case P75:
                  return snapshot.get75thPercentile();
              case P95:
                  return snapshot.get95thPercentile();
              case P98:
                  return snapshot.get98thPercentile();
              case P99:
                  return snapshot.get99thPercentile();
              case P999:
                  return snapshot.get999thPercentile();
              case MAX:
                  return snapshot.getMax();
              case MEAN:
                  return snapshot.getMean();
              case MIN:
                  return snapshot.getMin();
              case STDDEV:
                  return snapshot.getStdDev();
              default:
                  throw new RuntimeException("Shouldn't happen");
          }
      }
  
      static double getRate(Meter meter, Rate rate)
      {
          switch (rate)
          {
              case RATE15_MIN:
                  return meter.getFifteenMinuteRate();
              case RATE5_MIN:
                  return meter.getFiveMinuteRate();
              case RATE1_MIN:
                  return meter.getOneMinuteRate();
              case RATE_MEAN:
                  return meter.getMeanRate();
              default:
                  throw new RuntimeException("Shouldn't happen");
          }
      }
  }
  