JingsongLi commented on a change in pull request #8881: [FLINK-12660][hive] Integrate Flink with Hive UDAF URL: https://github.com/apache/flink/pull/8881#discussion_r298029105
########## File path: flink-connectors/flink-connector-hive/src/main/java/org/apache/flink/table/functions/hive/HiveGenericUDAF.java ########## @@ -0,0 +1,215 @@ +/* + * 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.functions.hive; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.api.common.typeinfo.TypeInformation; +import org.apache.flink.table.catalog.hive.util.HiveTypeUtil; +import org.apache.flink.table.functions.AggregateFunction; +import org.apache.flink.table.functions.FunctionContext; +import org.apache.flink.table.functions.hive.conversion.HiveInspectors; +import org.apache.flink.table.functions.hive.conversion.HiveObjectConversion; +import org.apache.flink.table.functions.hive.conversion.IdentityConversion; +import org.apache.flink.table.types.DataType; +import org.apache.flink.table.types.utils.LegacyTypeInfoDataTypeConverter; + +import org.apache.hadoop.hive.ql.exec.UDAF; +import org.apache.hadoop.hive.ql.metadata.HiveException; +import org.apache.hadoop.hive.ql.parse.SemanticException; +import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFBridge; +import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator; +import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFResolver2; +import org.apache.hadoop.hive.ql.udf.generic.SimpleGenericUDAFParameterInfo; +import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector; + +import java.util.Arrays; + +/** + * An {@link AggregateFunction} implementation that calls Hive's {@link UDAF} or {@link GenericUDAFEvaluator}. + */ +@Internal +public class HiveGenericUDAF + extends AggregateFunction<Object, GenericUDAFEvaluator.AggregationBuffer> implements HiveFunction { + + private final HiveFunctionWrapper hiveFunctionWrapper; + // Flag that indicates whether a bridge between GenericUDAF and UDAF is required. + // Old UDAF can be used with the GenericUDAF infrastructure through bridging. + private final boolean isUDAFBridgeRequired; + + private Object[] constantArguments; + private DataType[] argTypes; + + private transient GenericUDAFEvaluator partialEvaluator; + private transient GenericUDAFEvaluator finalEvaluator; + private transient ObjectInspector finalResult; + private transient HiveObjectConversion[] conversions; + private transient boolean allIdentityConverter; + private transient boolean initialized; + + public HiveGenericUDAF(HiveFunctionWrapper funcWrapper) { + this(funcWrapper, false); + } + + public HiveGenericUDAF(HiveFunctionWrapper funcWrapper, boolean isUDAFBridgeRequired) { + this.hiveFunctionWrapper = funcWrapper; + this.isUDAFBridgeRequired = isUDAFBridgeRequired; + } + + @Override + public void open(FunctionContext context) throws Exception { + super.open(context); + init(); + } + + private void init() throws HiveException { + ObjectInspector[] inputInspectors = HiveInspectors.toInspectors(constantArguments, argTypes); + + // Flink UDAF only supports Hive UDAF's PARTIAL_1 and FINAL mode + + // PARTIAL1: from original data to partial aggregation data: + // iterate() and terminatePartial() will be called. + this.partialEvaluator = createEvaluator(inputInspectors); + ObjectInspector partialResult = partialEvaluator.init(GenericUDAFEvaluator.Mode.PARTIAL1, inputInspectors); + + // FINAL: from partial aggregation to full aggregation: + // merge() and terminate() will be called. + this.finalEvaluator = createEvaluator(inputInspectors); + this.finalResult = finalEvaluator.init( + GenericUDAFEvaluator.Mode.FINAL, new ObjectInspector[]{ partialResult }); + + conversions = new HiveObjectConversion[inputInspectors.length]; + for (int i = 0; i < inputInspectors.length; i++) { + conversions[i] = HiveInspectors.getConversion(inputInspectors[i], argTypes[i].getLogicalType()); + } + allIdentityConverter = Arrays.stream(conversions) + .allMatch(conv -> conv instanceof IdentityConversion); + + initialized = true; + } + + private GenericUDAFEvaluator createEvaluator(ObjectInspector[] inputInspectors) throws SemanticException { + GenericUDAFResolver2 resolver; + + if (isUDAFBridgeRequired) { + resolver = new GenericUDAFBridge((UDAF) hiveFunctionWrapper.createFunction()); + } else { + resolver = (GenericUDAFResolver2) hiveFunctionWrapper.createFunction(); + } + + return resolver.getEvaluator( + new SimpleGenericUDAFParameterInfo( + inputInspectors, + // The flag to indicate if the UDAF invocation was from the windowing function call or not. 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