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
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   */
  package org.apache.beam.sdk.extensions.sql.impl.planner;
  
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.RelNode;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.metadata.JaninoRelMetadataProvider;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.metadata.RelMetadataQuery;
  
  public class BeamRelMetadataQuery extends RelMetadataQuery {
    private NodeStatsMetadata.Handler nodeStatsMetadataHandler;
  
    private BeamRelMetadataQuery() {
      nodeStatsMetadataHandler = initialHandler(NodeStatsMetadata.Handler.class);
    }
  
    public static BeamRelMetadataQuery instance() {
      return new BeamRelMetadataQuery();
    }
  
    public NodeStats getNodeStats(RelNode relNode) {
      // Note this infinite loop was duplicated from logic in Calcite's RelMetadataQuery.get* methods
      for (; ; ) {
        try {
          NodeStats result = nodeStatsMetadataHandler.getNodeStats(relNode, this);
          return result;
        } catch (JaninoRelMetadataProvider.NoHandler e) {
          nodeStatsMetadataHandler = revise(e.relClass, NodeStatsMetadata.DEF);
        }
      }
    }
  }
  