iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/transformation/dag/column/multi/MappableUDFColumnTransformer.java

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 * 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
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 *
 *     http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.iotdb.db.queryengine.transformation.dag.column.multi;

import org.apache.iotdb.db.queryengine.transformation.dag.column.ColumnTransformer;
import org.apache.iotdb.db.queryengine.transformation.dag.udf.UDTFExecutor;
import org.apache.iotdb.tsfile.read.common.block.column.Column;
import org.apache.iotdb.tsfile.read.common.block.column.ColumnBuilder;
import org.apache.iotdb.tsfile.read.common.type.Type;

public class MappableUDFColumnTransformer extends ColumnTransformer {

  private final ColumnTransformer[] inputColumnTransformers;

  private final UDTFExecutor executor;

  public MappableUDFColumnTransformer(
      Type returnType, ColumnTransformer[] inputColumnTransformers, UDTFExecutor executor) {
    super(returnType);
    this.inputColumnTransformers = inputColumnTransformers;
    this.executor = executor;
  }

  @Override
  public void evaluate() {
    // pull columns from previous transformers
    for (ColumnTransformer inputColumnTransformer : inputColumnTransformers) {
      inputColumnTransformer.tryEvaluate();
    }
    // construct input TsBlock with columns
    int size = inputColumnTransformers.length;
    Column[] columns = new Column[size];
    for (int i = 0; i < size; i++) {
      columns[i] = inputColumnTransformers[i].getColumn();
    }
    // construct TsBlockBuilder
    int count = inputColumnTransformers[0].getColumnCachePositionCount();
    ColumnBuilder builder = returnType.createColumnBuilder(count);
    // executor UDF and cache result
    executor.execute(columns, builder);
    initializeColumnCache(builder.build());
  }

  @Override
  protected void checkType() {
    // do nothing
  }

  public ColumnTransformer[] getInputColumnTransformers() {
    return inputColumnTransformers;
  }

  @Override
  public void close() {
    // finalize executor
    executor.beforeDestroy();
  }
}