bziobrowski commented on code in PR #15245: URL: https://github.com/apache/pinot/pull/15245#discussion_r1991802263
########## pinot-query-runtime/src/main/java/org/apache/pinot/query/runtime/blocks/MseBlock.java: ########## @@ -0,0 +1,178 @@ +/** + * 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.pinot.query.runtime.blocks; + +import org.apache.pinot.common.utils.DataSchema; +import org.apache.pinot.core.common.Block; + + +/// Blocks used by [MultiStageOperator][org.apache.pinot.query.runtime.operator.MultiStageOperator] to share +/// information. +/// +/// Blocks always go from upstream (the children of the operator) to downstream (the parent of the operator) and can be +/// classified in the following categories: +/// - [Data] blocks: contain data that can be processed by the operator. +/// - [Eos] blocks: signal the end of a stream. These blocks can be either [successful][SuccessMseBlock] or +/// [error][ErrorMseBlock]. +/// +/// ## The MseBlock API +/// A MseBlock itself is not very useful, as they have almost no methods. +/// Instead, they are used as a common sub-interface for [data][Data] and [end-of-stream][Eos] blocks, +/// which are then subclassed to provide the actual functionality. +/// This pattern follows the principles of Java 17 sealed interfaces and the intention is implement them as such once +/// Pinot source code is migrated to Java 17 or newer, specially in Java 21 where pattern matching can also be used, +/// removing the need for the [Visitor] pattern. +/// +/// Meanwhile, the API force callers to do some castings, but it is a trade-off to have a more robust and maintainable +/// codebase given that we can relay on Java typesystem to verify some important properties at compile time instead of +/// adding runtime checks. +/// Review Comment: `alternative of` -> `alternative to` -- 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: commits-unsubscr...@pinot.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
