flink-libraries/flink-table/src/main/scala/org/apache/flink/table/codegen/GeneratedClass.scala

/*
 * 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.flink.table.codegen

import org.codehaus.commons.compiler.CompileException

/**
  * A wrapper for generated class, defines a `newInstance` method so that get the instance by
  * reference objects.
  */
trait GeneratedClass[T] {

  def name: String

  /**
    * 'var' type makes sure we can set it as null after the code is compiled to be GC friendly.
    */
  var code: String

  def references: Array[AnyRef]

  @throws(classOf[CompileException])
  private def compile(cl: ClassLoader): Class[T] = {
    val ret: Class[T] = CodeGenUtils.compile(cl, name, code)
    // Set the code as null to be GC friendly
    code = null
    ret
  }

  @throws(classOf[CompileException])
  def newInstance(cl: ClassLoader): T = {
    compile(cl).getConstructor(classOf[Array[AnyRef]]).newInstance(references)
  }
}