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 com.google.common.base.Joiner;
  import io.prometheus.client.Collector;
  import java.util.Map;
  import java.util.TreeMap;
  import org.apache.bookkeeper.stats.Counter;
  import org.apache.bookkeeper.stats.Gauge;
  import org.apache.bookkeeper.stats.OpStatsLogger;
  import org.apache.bookkeeper.stats.StatsLogger;
  
  /**
   * A {@code Prometheus} based {@link StatsLogger} implementation.
   */
  public class PrometheusStatsLogger implements StatsLogger {
  
      private final PrometheusMetricsProvider provider;
      private final String scope;
      private final Map<String, String> labels;
  
      PrometheusStatsLogger(PrometheusMetricsProvider provider, String scope, Map<String, String> labels) {
          this.provider = provider;
          this.scope = scope;
          this.labels = labels;
      }
  
      @Override
      public OpStatsLogger getOpStatsLogger(String name) {
          return provider.opStats.computeIfAbsent(scopeContext(name), x -> new DataSketchesOpStatsLogger(labels));
      }
  
      @Override
      public OpStatsLogger getThreadScopedOpStatsLogger(String name) {
          return provider.threadScopedOpStats.computeIfAbsent(scopeContext(name),
                  x -> new ThreadScopedDataSketchesStatsLogger(provider, x, labels));
      }
  
      @Override
      public Counter getCounter(String name) {
          return provider.counters.computeIfAbsent(scopeContext(name), x -> new LongAdderCounter(labels));
      }
  
      public Counter getThreadScopedCounter(String name) {
          return provider.threadScopedCounters.computeIfAbsent(scopeContext(name),
                  x -> new ThreadScopedLongAdderCounter(provider, x, labels));
      }
  
      @Override
      public <T extends Number> void registerGauge(String name, Gauge<T> gauge) {
          provider.gauges.computeIfAbsent(scopeContext(name), x -> new SimpleGauge<T>(gauge, labels));
      }
  
      @Override
      public <T extends Number> void unregisterGauge(String name, Gauge<T> gauge) {
          // no-op
      }
  
      @Override
      public void removeScope(String name, StatsLogger statsLogger) {
          // no-op
      }
  
      @Override
      public StatsLogger scope(String name) {
          return new PrometheusStatsLogger(provider, completeName(name), labels);
      }
  
      @Override
      public StatsLogger scopeLabel(String labelName, String labelValue) {
          Map<String, String> newLabels = new TreeMap<>(labels);
          newLabels.put(labelName, labelValue);
          return new PrometheusStatsLogger(provider, scope, newLabels);
      }
  
      private ScopeContext scopeContext(String name) {
          return new ScopeContext(completeName(name), labels);
      }
  
      private String completeName(String name) {
          return Collector.sanitizeMetricName(scope.isEmpty() ? name : Joiner.on('_').join(scope, name));
      }
  }
  