andygrove commented on code in PR #4267: URL: https://github.com/apache/datafusion-comet/pull/4267#discussion_r3227329812
########## common/src/main/java/org/apache/comet/udf/CometBatchKernel.java: ########## @@ -0,0 +1,68 @@ +/* + * 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.comet.udf; + +import org.apache.arrow.vector.FieldVector; +import org.apache.arrow.vector.ValueVector; + +/** + * Abstract base extended by the Janino-compiled batch kernel emitted by {@code + * CometBatchKernelCodegen}. The generated subclass extends {@code CometInternalRow} (so Spark's + * {@code BoundReference.genCode} can call {@code this.getUTF8String(ord)} directly) and carries + * typed input fields baked at codegen time, one per input column. Expression evaluation plus Arrow + * read/write fuse into one method per expression tree. + * + * <p>Input scope: any {@code ValueVector[]}; the generated subclass casts each slot to the concrete + * Arrow type the compile-time schema specified. Output is a generic {@code FieldVector}; the + * generated subclass casts to the concrete type matching the bound expression's {@code dataType}. + * Widen input support by adding vector classes to the getter switch in {@code + * CometBatchKernelCodegen.emitTypedGetters}; widen output support by adding cases in {@code + * CometBatchKernelCodegen.allocateOutput} and {@code emitOutputWriter}. + */ +public abstract class CometBatchKernel extends CometInternalRow { + + protected final Object[] references; + + protected CometBatchKernel(Object[] references) { + this.references = references; + } + + /** + * Process one batch. + * + * @param inputs Arrow input vectors; length and concrete classes must match the schema the kernel + * was compiled against + * @param output Arrow output vector; caller allocates to the expression's {@code dataType} + * @param numRows number of rows in this batch + */ + public abstract void process(ValueVector[] inputs, FieldVector output, int numRows); + + /** + * Run partition-dependent initialization. The generated subclass overrides this to execute + * statements collected via {@code CodegenContext.addPartitionInitializationStatement}, for + * example reseeding {@code Rand}'s {@code XORShiftRandom} from {@code seed + partitionIndex}. + * Deterministic expressions leave this as a no-op. + * + * <p>The caller must invoke this before the first {@code process} call of each partition. The + * generated subclass is not thread-safe across concurrent {@code process} calls, so kernels are + * allocated per dispatcher invocation and init is run once on the fresh instance. + */ + public void init(int partitionIndex) {} Review Comment: nit: I think moving `init` before `process` helps with reading this -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
