Github user jose-torres commented on a diff in the pull request:
https://github.com/apache/spark/pull/22009#discussion_r209019530
--- Diff:
sql/core/src/main/java/org/apache/spark/sql/sources/v2/reader/streaming/StreamingReadSupport.java
---
@@ -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.sql.sources.v2.reader.streaming;
+
+import org.apache.spark.sql.sources.v2.reader.ReadSupport;
+
+/**
+ * A base interface for streaming read support. This is package private
and is invisible to data
+ * sources. Data sources should implement concrete streaming read support
interfaces:
+ * {@link MicroBatchReadSupport} or {@link ContinuousReadSupport}.
+ */
+interface StreamingReadSupport extends ReadSupport {
+
+ /**
+ * Returns the initial offset for a streaming query to start reading
from. Note that the
+ * streaming data source should not assume that it will start reading
from its
+ * {@link #initialOffset()} value: if Spark is restarting an existing
query, it will restart from
+ * the check-pointed offset rather than the initial one.
+ */
+ Offset initialOffset();
+
+ /**
+ * Deserialize a JSON string into an Offset of the
implementation-defined offset type.
+ *
+ * @throws IllegalArgumentException if the JSON does not encode a valid
offset for this reader
+ */
+ Offset deserializeOffset(String json);
+
+ /**
+ * Informs the source that Spark has completed processing all data for
offsets less than or
+ * equal to `end` and will only request offsets greater than `end` in
the future.
+ */
+ void commit(Offset end);
--- End diff --
I'd +1 passing a ScanConfig. I agree that all the existing sources are just
going to pull out the offset, but "Spark is finished with this scan" is a
cleaner semantic than "Spark is finished with the scan such that it goes up to
this offset".
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