[GitHub] [spark] dongjoon-hyun commented on a change in pull request #31876: [SPARK-34942][API][CORE] Abstract Location in MapStatus to enable support for custom storage

[GitBox <gi...@apache.org>]

dongjoon-hyun commented on a change in pull request #31876:
URL: https://github.com/apache/spark/pull/31876#discussion_r618065324



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File path: core/src/main/java/org/apache/spark/shuffle/api/Location.java
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@@ -0,0 +1,49 @@
+/*
+ * 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.shuffle.api;
+
+import org.apache.spark.annotation.Private;
+
+import java.io.Externalizable;
+import java.io.ObjectInput;
+import java.io.ObjectOutput;
+
+
+/**
+ * :: Private ::
+ * An interface for plugging in the location of shuffle files, in order to support store shuffle
+ * data in different storage, e.g., BlockManager, HDFS, S3. It would be generated by
+ * {@link ShuffleMapOutputWriter} after writing a shuffle data file and used by ShuffleMapOutputReader
+ * to read the shuffle data.
+ *
+ * Since the location is returned by {@link ShuffleMapOutputWriter#commitAllPartitions()} at executor
+ * and would be sent to driver, users must ensure the location is serializable by
+ *
+ *  - implement a 0-arg constructor
+ *  - implement {@link java.io.Externalizable#readExternal(ObjectInput)} for deserialization
+ *  - implement {@link java.io.Externalizable#writeExternal(ObjectOutput)} for serialization
+ *
+ * Since the location will be used as keys in maps or comparing with others, users must ensure that

Review comment:
       This is annotated with `Private`. `users` looks a little too broad in this context.




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