org.apache.drill.exec.expr.fn.DrillFunctionRegistry Maven / Gradle / Ivy

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/**
 * 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.drill.exec.expr.fn;

import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;

import org.apache.calcite.sql.SqlOperator;
import org.apache.drill.common.scanner.persistence.AnnotatedClassDescriptor;
import org.apache.drill.common.scanner.persistence.ScanResult;
import org.apache.drill.exec.expr.DrillFunc;
import org.apache.drill.exec.planner.logical.DrillConstExecutor;
import org.apache.drill.exec.planner.sql.DrillOperatorTable;
import org.apache.drill.exec.planner.sql.DrillSqlAggOperator;
import org.apache.drill.exec.planner.sql.DrillSqlOperator;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Sets;

public class DrillFunctionRegistry {
  static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(DrillFunctionRegistry.class);

  private ArrayListMultimap methods = ArrayListMultimap.create();

  /* Hash map to prevent registering functions with exactly matching signatures
   * key: Function Name + Input's Major Type
   * Value: Class name where function is implemented
   */
  private HashMap functionSignatureMap = new HashMap<>();

  public DrillFunctionRegistry(ScanResult classpathScan) {
    FunctionConverter converter = new FunctionConverter();
    List providerClasses = classpathScan.getAnnotatedClasses();
    for (AnnotatedClassDescriptor func : providerClasses) {
      DrillFuncHolder holder = converter.getHolder(func);
      if (holder != null) {
        // register handle for each name the function can be referred to
        String[] names = holder.getRegisteredNames();

        // Create the string for input types
        String functionInput = "";
        for (DrillFuncHolder.ValueReference ref : holder.parameters) {
          functionInput += ref.getType().toString();
        }
        for (String name : names) {
          String functionName = name.toLowerCase();
          methods.put(functionName, holder);
          String functionSignature = functionName + functionInput;
          String existingImplementation;
          if ((existingImplementation = functionSignatureMap.get(functionSignature)) != null) {
            throw new AssertionError(
                String.format(
                    "Conflicting functions with similar signature found. Func Name: %s, Class name: %s " +
                " Class name: %s", functionName, func.getClassName(), existingImplementation));
          } else if (holder.isAggregating() && !holder.isDeterministic() ) {
            logger.warn("Aggregate functions must be deterministic, did not register function {}", func.getClassName());
          } else {
            functionSignatureMap.put(functionSignature, func.getClassName());
          }
        }
      } else {
        logger.warn("Unable to initialize function for class {}", func.getClassName());
      }
    }
    if (logger.isTraceEnabled()) {
      StringBuilder allFunctions = new StringBuilder();
      for (DrillFuncHolder method: methods.values()) {
        allFunctions.append(method.toString()).append("\n");
      }
      logger.trace("Registered functions: [\n{}]", allFunctions);
    }
  }

  public int size(){
    return methods.size();
  }

  /** Returns functions with given name. Function name is case insensitive. */
  public List getMethods(String name) {
    return this.methods.get(name.toLowerCase());
  }

  public void register(DrillOperatorTable operatorTable) {
    SqlOperator op;
    for (Entry> function : methods.asMap().entrySet()) {
      Set argCounts = Sets.newHashSet();
      String name = function.getKey().toUpperCase();
      for (DrillFuncHolder func : function.getValue()) {
        if (argCounts.add(func.getParamCount())) {
          if (func.isAggregating()) {
            op = new DrillSqlAggOperator(name, func.getParamCount());
          } else {
            boolean isDeterministic;
            // prevent Drill from folding constant functions with types that cannot be materialized
            // into literals
            if (DrillConstExecutor.NON_REDUCIBLE_TYPES.contains(func.getReturnType().getMinorType())) {
              isDeterministic = false;
            } else {
              isDeterministic = func.isDeterministic();
            }
            op = new DrillSqlOperator(name, func.getParamCount(), func.getReturnType(), isDeterministic);
          }
          operatorTable.add(function.getKey(), op);
        }
      }
    }
  }

}