[GitHub] flink pull request #5116: [FLINK-8191] [Kafka Connector] Add a RoundRobinPar...

[tzulitai]

Github user tzulitai commented on a diff in the pull request:

    https://github.com/apache/flink/pull/5116#discussion_r156233850
  
    --- Diff: 
flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/partitioner/FlinkRoundRobinPartitioner.java
 ---
    @@ -0,0 +1,72 @@
    +/*
    + * 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.streaming.connectors.kafka.partitioner;
    +
    +import org.apache.flink.util.Preconditions;
    +
    +/**
    + * A partitioner ensuring that each internal Flink partition communicate 
with Kafka partition in round robin manner.
    + *
    + * <p>Note, one Kafka partition can contain multiple Flink partitions.
    + *
    + * <p>Cases:
    + *         # More Flink partitions than kafka partitions
    + * <pre>
    + *                 Flink Sinks:            Kafka Partitions
    + *                         1       ----------------&gt;    1
    + *                         2   --------------/
    + *                         3   -------------/
    + *                         4       ------------/
    + * </pre>
    + * Some (or all) kafka partitions contain the output of more than one 
flink partition
    + *
    + * <p>Fewer Flink partitions than Kafka
    + * <pre>
    + *                 Flink Sinks:            Kafka Partitions
    + *                         1       ----------------&gt;    1
    + *                         2       ----------------&gt;    2
    + *                                                                         
        3
    + *                                                                         
        4
    + *                                                                         
        5
    + * </pre>
    --- End diff --
    
    The above illustrations do not convey the fact that this is a 
`RoundRobinPartitioner`.
    For example, the exact same illustrations can also work for the 
`FlinkFixedPartitioner`.


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