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.index.sai.metrics;
  
  import java.util.concurrent.TimeUnit;
  
  /**
   * Listener that gets notified during storage-attached index query execution.
   */
  public interface QueryEventListener
  {
      /**
       * Collector for balanced tree file related metrics.
       */
      interface BalancedTreeEventListener
      {
          /**
           * Per-segment balanced tree index intersection time in given units. Recorded when intersection completes.
           */
          void onIntersectionComplete(long intersectionTotalTime, TimeUnit unit);
  
          /**
           * When an intersection exits early due to the query shape being completely outside the min/max range.
           */
          void onIntersectionEarlyExit();
  
          /**
           * How many balanced tree posting list were matched during the intersection.
           */
          void postingListsHit(int count);
  
          /**
           * When query potentially matches value range within a segment, and we need to do a traversal.
           */
          void onSegmentHit();
  
          /**
           * Returns events listener for balanced tree postings.
           */
          PostingListEventListener postingListEventListener();
      }
  
      interface TrieIndexEventListener
      {
          /**
           * When query potentially matches value range within a segment, and we need to do a traversal.
           */
          void onSegmentHit();
  
          /**
           * Per-segment trie index traversal time in given units. Recorded when traversal completes.
           */
          void onTraversalComplete(long traversalTotalTime, TimeUnit unit);
  
          /**
           * Returns events listener for trie postings.
           */
          PostingListEventListener postingListEventListener();
      }
  
      /**
       * Collector for posting file related metrics.
       */
      interface PostingListEventListener
      {
          /**
           * When an individual posting lists is advanced.
           */
          void onAdvance();
  
          /**
           * When a posting is successfully read from disk and decoded.
           */
          void postingDecoded(long postingsDecoded);
  
          PostingListEventListener NO_OP = new PostingListEventListener()
          {
              @Override
              public void onAdvance()
              {
              }
  
              @Override
              public void postingDecoded(long postingsDecoded)
              {
              }
          };
      }
  }
  