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 limitations
   * under the License.
   */
  
  package org.apache.asterix.external.library;
  
  import static org.apache.asterix.om.types.EnumDeserializer.ATYPETAGDESERIALIZER;
  
  import org.apache.asterix.common.exceptions.ErrorCode;
  import org.apache.asterix.common.exceptions.RuntimeDataException;
  import org.apache.asterix.common.metadata.Namespace;
  import org.apache.asterix.external.api.IExternalScalarFunction;
  import org.apache.asterix.external.api.IFunctionFactory;
  import org.apache.asterix.om.functions.IExternalFunctionInfo;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.IAType;
  import org.apache.asterix.runtime.evaluators.functions.PointableHelper;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
  import org.apache.hyracks.api.context.IEvaluatorContext;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.data.std.api.IPointable;
  import org.apache.hyracks.data.std.primitive.VoidPointable;
  import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
  import org.apache.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
  
  class ExternalScalarJavaFunctionEvaluator extends ExternalScalarFunctionEvaluator {
  
      private final IExternalScalarFunction externalFunctionInstance;
      private final IPointable inputVal = VoidPointable.FACTORY.createPointable();
      private final ArrayBackedValueStorage resultBuffer = new ArrayBackedValueStorage();
      protected final JavaFunctionHelper functionHelper;
  
      ExternalScalarJavaFunctionEvaluator(IExternalFunctionInfo finfo, IScalarEvaluatorFactory[] args, IAType[] argTypes,
              IEvaluatorContext context) throws HyracksDataException {
          super(finfo, args, argTypes, context);
  
          Namespace libraryNamespace = finfo.getLibraryNamespace();
          String libraryName = finfo.getLibraryName();
          JavaLibrary library = (JavaLibrary) libraryManager.getLibrary(libraryNamespace, libraryName);
  
          String classname = finfo.getExternalIdentifier().get(0);
          try {
              //first, check if this class is assignable to the correct interface before running static initializers that
              //may be dangerous
              Class<?> clazz = Class.forName(classname, false, library.getClassLoader());
              if (IFunctionFactory.class.isAssignableFrom(clazz)) {
                  //check if clazz implements IFunctionFactory
                  IFunctionFactory externalFunctionFactory = (IFunctionFactory) clazz.newInstance();
                  externalFunctionInstance = (IExternalScalarFunction) externalFunctionFactory.getExternalFunction();
              } else {
                  throw new ClassCastException("Specified class does not implement IFunctionFactory");
              }
          } catch (Exception e) {
              throw new RuntimeDataException(ErrorCode.LIBRARY_EXTERNAL_FUNCTION_UNABLE_TO_LOAD_CLASS, e, classname);
          }
  
          functionHelper = new JavaFunctionHelper(finfo, argTypes, resultBuffer);
          try {
              externalFunctionInstance.initialize(functionHelper);
          } catch (Exception e) {
              throw HyracksDataException.create(e);
          }
      }
  
      @Override
      public void evaluate(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
          try {
              boolean nullCall = finfo.getNullCall();
              boolean hasNullArg = false;
              for (int i = 0; i < argEvals.length; i++) {
                  argEvals[i].evaluate(tuple, inputVal);
                  if (!nullCall) {
                      byte[] inputValBytes = inputVal.getByteArray();
                      int inputValStartOffset = inputVal.getStartOffset();
                      ATypeTag typeTag = ATYPETAGDESERIALIZER.deserialize(inputValBytes[inputValStartOffset]);
                      if (typeTag == ATypeTag.MISSING) {
                          PointableHelper.setMissing(result);
                          return;
                      } else if (typeTag == ATypeTag.NULL) {
                          hasNullArg = true;
                      }
                  }
                  functionHelper.setArgument(i, inputVal);
              }
              if (!nullCall && hasNullArg) {
                  PointableHelper.setNull(result);
              } else {
                  resultBuffer.reset();
                  externalFunctionInstance.evaluate(functionHelper);
                  if (!functionHelper.isValidResult()) {
                      throw new RuntimeDataException(ErrorCode.EXTERNAL_UDF_RESULT_TYPE_ERROR);
                  }
                  result.set(resultBuffer.getByteArray(), resultBuffer.getStartOffset(), resultBuffer.getLength());
                  functionHelper.reset();
              }
          } catch (Exception e) {
              throw HyracksDataException.create(e);
          }
      }
  }
  