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 java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.TimeUnit;
  import org.apache.bookkeeper.stats.Counter;
  import org.apache.bookkeeper.stats.ThreadRegistry;
  
  /**
   * {@link Counter} implementation that lazily registers LongAdderCounters per thread
   *  * with added labels for the threadpool/thread name and thread no.
   */
  public class ThreadScopedLongAdderCounter implements Counter {
      private ThreadLocal<LongAdderCounter> counters;
      private LongAdderCounter defaultCounter;
      private Map<String, String> originalLabels;
      private ScopeContext scopeContext;
      private PrometheusMetricsProvider provider;
  
      public ThreadScopedLongAdderCounter(PrometheusMetricsProvider provider,
                                          ScopeContext scopeContext,
                                          Map<String, String> labels) {
          this.provider = provider;
          this.scopeContext = scopeContext;
          this.originalLabels = new HashMap<>(labels);
          this.defaultCounter = new LongAdderCounter(labels);
          Map<String, String> defaultLabels = new HashMap<>(labels);
          defaultLabels.put("threadPool", "?");
          defaultLabels.put("thread", "?");
          this.defaultCounter.initializeThread(defaultLabels);
  
          this.counters = ThreadLocal.withInitial(() -> {
              return new LongAdderCounter(labels);
          });
      }
  
      @Override
      public void clear() {
          getCounter().clear();
      }
  
      @Override
      public void inc() {
          getCounter().inc();
      }
  
      @Override
      public void dec() {
          getCounter().dec();
      }
  
      @Override
      public void addCount(long delta) {
          getCounter().addCount(delta);
      }
  
      @Override
      public void addLatency(long eventLatency, TimeUnit unit) {
          getCounter().addLatency(eventLatency, unit);
      }
  
      @Override
      public Long get() {
          return getCounter().get();
      }
  
      private LongAdderCounter getCounter() {
          LongAdderCounter counter = counters.get();
  
          // Lazy registration
          // Update the counter with the thread labels then add to the provider
          // If for some reason this thread did not get registered,
          // then we fallback to a standard counter (defaultCounter)
          if (!counter.isThreadInitialized()) {
              ThreadRegistry.ThreadPoolThread tpt = ThreadRegistry.get();
  
              if (tpt == null) {
                  counters.set(defaultCounter);
                  provider.counters.put(new ScopeContext(scopeContext.getScope(), originalLabels), defaultCounter);
                  return defaultCounter;
              } else {
                  Map<String, String> threadScopedlabels = new HashMap<>(originalLabels);
                  threadScopedlabels.put("threadPool", tpt.getThreadPool());
                  threadScopedlabels.put("thread", String.valueOf(tpt.getOrdinal()));
  
                  counter.initializeThread(threadScopedlabels);
                  provider.counters.put(new ScopeContext(scopeContext.getScope(), threadScopedlabels), counter);
              }
          }
  
          return counter;
      }
  }
  