viirya commented on code in PR #55620: URL: https://github.com/apache/spark/pull/55620#discussion_r3255162698
########## common/network-common/src/main/java/org/apache/spark/network/shuffle/streaming/CreditControlMessage.java: ########## @@ -0,0 +1,73 @@ +/* + * 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.spark.network.shuffle.streaming; + +import io.netty.buffer.ByteBuf; +import io.netty.buffer.CompositeByteBuf; + +/** + * Sent from the client to the server to indicate that the client is ready to receive + * the specified amount of messages from the server. + */ +public final class CreditControlMessage extends StreamingShuffleMessage { + public int shuffleWriterId; + public int shuffleReaderId; + + public int numMessages; Review Comment: This field is going onto the wire and will be hard to change later, but its precise meaning isn't specified. From the PR description, this message is "reserved for finer-grained credit-based flow control in future revisions" — but numMessages = 5 could mean any of: - Credit grant (delta): writer may send 5 more DataMessages in addition to existing credit. - Credit window (absolute): writer's send budget is now 5, replacing the previous value. - Cumulative ack: reader has received 5 messages so far. - Initial buffer hint: handshake-only signal of receive-queue size. Since part 1 has no caller yet, none of these are disambiguated by code. Once a handler PR lands assuming one interpretation, switching is a wire-format break. Suggest committing to one interpretation in javadoc now, e.g.: ```java /** * Sent from reader to writer to grant additional send credit. After * receiving this message, the writer may send up to {@code numMessages} * additional DataMessages beyond any previously-granted credit. */ public int numMessages; ``` -- 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]
