[GitHub] spark pull request #21106: [SPARK-23711][SQL] Add fallback generator for Uns...

[cloud-fan <gi...@git.apache.org>]

Github user cloud-fan commented on a diff in the pull request:

    https://github.com/apache/spark/pull/21106#discussion_r187986602
  
    --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/CodeGeneratorWithInterpretedFallback.scala ---
    @@ -0,0 +1,80 @@
    +/*
    + * 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.spark.sql.catalyst.expressions
    +
    +import org.codehaus.commons.compiler.CompileException
    +import org.codehaus.janino.InternalCompilerException
    +
    +import org.apache.spark.TaskContext
    +import org.apache.spark.sql.internal.SQLConf
    +import org.apache.spark.util.Utils
    +
    +/**
    + * Catches compile error during code generation.
    + */
    +object CodegenError {
    +  def unapply(throwable: Throwable): Option[Exception] = throwable match {
    +    case e: InternalCompilerException => Some(e)
    +    case e: CompileException => Some(e)
    +    case _ => None
    +  }
    +}
    +
    +/**
    + * Defines values for `SQLConf` config of fallback mode. Use for test only.
    + */
    +object CodegenObjectFactoryMode extends Enumeration {
    +  val AUTO, CODEGEN_ONLY, NO_CODEGEN = Value
    +
    +  def currentMode: CodegenObjectFactoryMode.Value = {
    +    // If we weren't on task execution, accesses that config.
    +    if (TaskContext.get == null) {
    +      val config = SQLConf.get.getConf(SQLConf.CODEGEN_FACTORY_MODE)
    +      CodegenObjectFactoryMode.withName(config)
    +    } else {
    +      CodegenObjectFactoryMode.AUTO
    +    }
    +  }
    +}
    +
    +/**
    + * A codegen object generator which creates objects with codegen path first. Once any compile
    + * error happens, it can fallbacks to interpreted implementation. In tests, we can use a SQL config
    + * `SQLConf.CODEGEN_FACTORY_MODE` to control fallback behavior.
    + */
    +abstract class CodeGeneratorWithInterpretedFallback[IN, OUT] {
    +
    +  def createObject(in: IN): OUT = {
    +    // We are allowed to choose codegen-only or no-codegen modes if under tests.
    +    if (Utils.isTesting && CodegenObjectFactoryMode.currentMode != CodegenObjectFactoryMode.AUTO) {
    --- End diff --
    
    now it's better to call it fallback mode?


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