jsancio commented on a change in pull request #9553: URL: https://github.com/apache/kafka/pull/9553#discussion_r549053981
########## File path: clients/src/main/resources/common/message/FetchSnapshotResponse.json ########## @@ -0,0 +1,59 @@ +// 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. + +{ + "apiKey": 59, + "type": "response", + "name": "FetchSnapshotResponse", + "validVersions": "0", + "flexibleVersions": "0+", + "fields": [ + { "name": "ThrottleTimeMs", "type": "int32", "versions": "0+", "ignorable": true, + "about": "The duration in milliseconds for which the request was throttled due to a quota violation, or zero if the request did not violate any quota." }, + { "name": "ErrorCode", "type": "int16", "versions": "0+", "ignorable": false, + "about": "The top level response error code." }, + { "name": "Topics", "type": "[]TopicSnapshot", "versions": "0+", + "about": "The topics to fetch.", "fields": [ + { "name": "Name", "type": "string", "versions": "0+", "entityType": "topicName", + "about": "The name of the topic to fetch." }, + { "name": "Partitions", "type": "[]PartitionSnapshot", "versions": "0+", + "about": "The partitions to fetch.", "fields": [ + { "name": "Index", "type": "int32", "versions": "0+", + "about": "The partition index." }, + { "name": "ErrorCode", "type": "int16", "versions": "0+", + "about": "The error code, or 0 if there was no fetch error." }, + { "name": "SnapshotId", "type": "SnapshotId", "versions": "0+", + "about": "The snapshot endOffset and epoch fetched", + "fields": [ + { "name": "EndOffset", "type": "int64", "versions": "0+" }, + { "name": "Epoch", "type": "int32", "versions": "0+" } + ]}, + { "name": "CurrentLeader", "type": "LeaderIdAndEpoch", + "versions": "0+", "taggedVersions": "0+", "tag": 0, "fields": [ + { "name": "LeaderId", "type": "int32", "versions": "0+", + "about": "The ID of the current leader or -1 if the leader is unknown."}, + { "name": "LeaderEpoch", "type": "int32", "versions": "0+", + "about": "The latest known leader epoch"} + ]}, + { "name": "Size", "type": "int64", "versions": "0+", + "about": "The total size of the snapshot." }, + { "name": "Position", "type": "int64", "versions": "0+", + "about": "The starting byte position within the snapshot included in the Bytes field." }, + { "name": "Bytes", "type": "bytes", "versions": "0+", "zeroCopy": true, Review comment: @dengziming, Thanks for the comment. The `FetchSnapshotRequest` differs from `FetchRequest` in that `Position` is a byte offset. Because of this we don't need an `Offset` to `Byte` index. If we implement option 1 in my comment above, we can still use `Records` by making sure that: 1. The `leaders` send at least one entire `RecordBatch` in the `FetchSnapshotResponse`. 2. The `followers` only write complete `RecordBatch`es by not writing bytes sent by the leader that are not complete `RecordBatch`. This guarantees that the `Position` sent in `FetchSnapshotRequest` is `RecordBatch` aligned and it always makes progress because the leader sends at least one complete `RecordBatch`. Having said that, I think we should try and implement option 2. Unfortunately, the Jira https://issues.apache.org/jira/browse/KAFKA-10694 doesn't document option 2. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected]
