Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/19861#discussion_r157140363
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/DataSourceV2Utils.scala
---
@@ -0,0 +1,58 @@
+/*
+ * 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.execution.datasources.v2
+
+import java.util.regex.Pattern
+
+import org.apache.spark.internal.Logging
+import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.sql.sources.v2.{DataSourceV2, SessionConfigSupport}
+
+private[sql] object DataSourceV2Utils extends Logging {
+
+ /**
+ * Helper method that extracts and transforms session configs into k/v
pairs, the k/v pairs will
+ * be used to create data source options.
+ * Only extract when `ds` implements [[SessionConfigSupport]], in this
case we may fetch the
+ * specified key-prefix from `ds`, and extract session configs with
config keys that start with
+ * `spark.datasource.$keyPrefix`. A session config
`spark.datasource.$keyPrefix.xxx -> yyy` will
+ * be transformed into `xxx -> yyy`.
+ *
+ * @param ds a [[DataSourceV2]] object
+ * @param conf the session conf
+ * @return an immutable map that contains all the extracted and
transformed k/v pairs.
+ */
+ def extractSessionConfigs(ds: DataSourceV2, conf: SQLConf): Map[String,
String] = ds match {
+ case cs: SessionConfigSupport =>
+ val keyPrefix = cs.keyPrefix()
+ require(keyPrefix != null, "The data source config key prefix can't
be null.")
+
+ val pattern =
Pattern.compile(s"^spark\\.datasource\\.$keyPrefix\\.(.*)")
--- End diff --
nit: `(.*)` -> `(.+)`. Just to forbid some corner case like
`spark.datasource.$keyPrefix.`
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