[SPARK-19853][SS] uppercase kafka topics fail when startingOffsets are SpecificOffsets

When using the KafkaSource with Structured Streaming, consumer assignments are not what the user expects if startingOffsets is set to an explicit set of topics/partitions in JSON where the topic(s) happen to have uppercase characters. When StartingOffsets is constructed, the original string value from options is transformed toLowerCase to make matching on "earliest" and "latest" case insensitive. However, the toLowerCase JSON is passed to SpecificOffsets for the terminal condition, so topic names may not be what the user intended by the time assignments are made with the underlying KafkaConsumer.

KafkaSourceProvider.scala:
```
val startingOffsets = caseInsensitiveParams.get(STARTING_OFFSETS_OPTION_KEY).map(_.trim.toLowerCase) match {
    case Some("latest") => LatestOffsets
    case Some("earliest") => EarliestOffsets
    case Some(json) => SpecificOffsets(JsonUtils.partitionOffsets(json))
    case None => LatestOffsets
  }
```

Thank cbowden for reporting.

Jenkins

Author: uncleGen <hustyugm@gmail.com>

Closes #17209 from uncleGen/SPARK-19853.

(cherry picked from commit 0a4d06a7)
Signed-off-by: Shixiong Zhu <shixiong@databricks.com>

external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/KafkaSourceProvider.scala

@@ -82,13 +82,8 @@ private[kafka010] class KafkaSourceProvider extends DataSourceRegister
         .map { k => k.drop(6).toString -> parameters(k) }
         .toMap
 
-    val startingStreamOffsets =
-      caseInsensitiveParams.get(STARTING_OFFSETS_OPTION_KEY).map(_.trim.toLowerCase) match {
-        case Some("latest") => LatestOffsetRangeLimit
-        case Some("earliest") => EarliestOffsetRangeLimit
-        case Some(json) => SpecificOffsetRangeLimit(JsonUtils.partitionOffsets(json))
-        case None => LatestOffsetRangeLimit
-      }
+    val startingStreamOffsets = KafkaSourceProvider.getKafkaOffsetRangeLimit(caseInsensitiveParams,
+      STARTING_OFFSETS_OPTION_KEY, LatestOffsetRangeLimit)
 
     val kafkaOffsetReader = new KafkaOffsetReader(
       strategy(caseInsensitiveParams),
@@ -128,19 +123,13 @@ private[kafka010] class KafkaSourceProvider extends DataSourceRegister
         .map { k => k.drop(6).toString -> parameters(k) }
         .toMap
 
-    val startingRelationOffsets =
-      caseInsensitiveParams.get(STARTING_OFFSETS_OPTION_KEY).map(_.trim.toLowerCase) match {
-        case Some("earliest") => EarliestOffsetRangeLimit
-        case Some(json) => SpecificOffsetRangeLimit(JsonUtils.partitionOffsets(json))
-        case None => EarliestOffsetRangeLimit
-      }
+    val startingRelationOffsets = KafkaSourceProvider.getKafkaOffsetRangeLimit(
+      caseInsensitiveParams, STARTING_OFFSETS_OPTION_KEY, EarliestOffsetRangeLimit)
+    assert(startingRelationOffsets != LatestOffsetRangeLimit)
 
-    val endingRelationOffsets =
-      caseInsensitiveParams.get(ENDING_OFFSETS_OPTION_KEY).map(_.trim.toLowerCase) match {
-        case Some("latest") => LatestOffsetRangeLimit
-        case Some(json) => SpecificOffsetRangeLimit(JsonUtils.partitionOffsets(json))
-        case None => LatestOffsetRangeLimit
-      }
+    val endingRelationOffsets = KafkaSourceProvider.getKafkaOffsetRangeLimit(caseInsensitiveParams,
+      ENDING_OFFSETS_OPTION_KEY, LatestOffsetRangeLimit)
+    assert(endingRelationOffsets != EarliestOffsetRangeLimit)
 
     val kafkaOffsetReader = new KafkaOffsetReader(
       strategy(caseInsensitiveParams),
@@ -388,34 +377,34 @@ private[kafka010] class KafkaSourceProvider extends DataSourceRegister
 
   private def validateBatchOptions(caseInsensitiveParams: Map[String, String]) = {
     // Batch specific options
-    caseInsensitiveParams.get(STARTING_OFFSETS_OPTION_KEY).map(_.trim.toLowerCase) match {
-      case Some("earliest") => // good to go
-      case Some("latest") =>
+    KafkaSourceProvider.getKafkaOffsetRangeLimit(
+      caseInsensitiveParams, STARTING_OFFSETS_OPTION_KEY, EarliestOffsetRangeLimit) match {
+      case EarliestOffsetRangeLimit => // good to go
+      case LatestOffsetRangeLimit =>
         throw new IllegalArgumentException("starting offset can't be latest " +
           "for batch queries on Kafka")
-      case Some(json) => (SpecificOffsetRangeLimit(JsonUtils.partitionOffsets(json)))
-        .partitionOffsets.foreach {
+      case SpecificOffsetRangeLimit(partitionOffsets) =>
+        partitionOffsets.foreach {
           case (tp, off) if off == KafkaOffsetRangeLimit.LATEST =>
             throw new IllegalArgumentException(s"startingOffsets for $tp can't " +
               "be latest for batch queries on Kafka")
           case _ => // ignore
         }
-      case _ => // default to earliest
     }
 
-    caseInsensitiveParams.get(ENDING_OFFSETS_OPTION_KEY).map(_.trim.toLowerCase) match {
-      case Some("earliest") =>
+    KafkaSourceProvider.getKafkaOffsetRangeLimit(
+      caseInsensitiveParams, ENDING_OFFSETS_OPTION_KEY, LatestOffsetRangeLimit) match {
+      case EarliestOffsetRangeLimit =>
         throw new IllegalArgumentException("ending offset can't be earliest " +
           "for batch queries on Kafka")
-      case Some("latest") => // good to go
-      case Some(json) => (SpecificOffsetRangeLimit(JsonUtils.partitionOffsets(json)))
-        .partitionOffsets.foreach {
+      case LatestOffsetRangeLimit => // good to go
+      case SpecificOffsetRangeLimit(partitionOffsets) =>
+        partitionOffsets.foreach {
           case (tp, off) if off == KafkaOffsetRangeLimit.EARLIEST =>
             throw new IllegalArgumentException(s"ending offset for $tp can't be " +
               "earliest for batch queries on Kafka")
           case _ => // ignore
         }
-      case _ => // default to latest
     }
 
     validateGeneralOptions(caseInsensitiveParams)
@@ -432,7 +421,7 @@ private[kafka010] class KafkaSourceProvider extends DataSourceRegister
 
     def set(key: String, value: Object): this.type = {
       map.put(key, value)
-      logInfo(s"$module: Set $key to $value, earlier value: ${kafkaParams.get(key).getOrElse("")}")
+      logInfo(s"$module: Set $key to $value, earlier value: ${kafkaParams.getOrElse(key, "")}")
       this
     }
 
@@ -450,10 +439,22 @@ private[kafka010] class KafkaSourceProvider extends DataSourceRegister
 
 private[kafka010] object KafkaSourceProvider {
   private val STRATEGY_OPTION_KEYS = Set("subscribe", "subscribepattern", "assign")
-  private val STARTING_OFFSETS_OPTION_KEY = "startingoffsets"
-  private val ENDING_OFFSETS_OPTION_KEY = "endingoffsets"
+  private[kafka010] val STARTING_OFFSETS_OPTION_KEY = "startingoffsets"
+  private[kafka010] val ENDING_OFFSETS_OPTION_KEY = "endingoffsets"
   private val FAIL_ON_DATA_LOSS_OPTION_KEY = "failondataloss"
   val TOPIC_OPTION_KEY = "topic"
 
   private val deserClassName = classOf[ByteArrayDeserializer].getName
+
+  def getKafkaOffsetRangeLimit(
+      params: Map[String, String],
+      offsetOptionKey: String,
+      defaultOffsets: KafkaOffsetRangeLimit): KafkaOffsetRangeLimit = {
+    params.get(offsetOptionKey).map(_.trim) match {
+      case Some(offset) if offset.toLowerCase == "latest" => LatestOffsetRangeLimit
+      case Some(offset) if offset.toLowerCase == "earliest" => EarliestOffsetRangeLimit
+      case Some(json) => SpecificOffsetRangeLimit(JsonUtils.partitionOffsets(json))
+      case None => defaultOffsets
+    }
+  }
 }

external/kafka-0-10-sql/src/test/scala/org/apache/spark/sql/kafka010/KafkaSourceSuite.scala

@@ -37,6 +37,7 @@ import org.apache.spark.SparkContext
 import org.apache.spark.sql.ForeachWriter
 import org.apache.spark.sql.execution.streaming._
 import org.apache.spark.sql.functions.{count, window}
+import org.apache.spark.sql.kafka010.KafkaSourceProvider._
 import org.apache.spark.sql.streaming.{ProcessingTime, StreamTest}
 import org.apache.spark.sql.test.{SharedSQLContext, TestSparkSession}
 
@@ -604,6 +605,24 @@ class KafkaSourceSuite extends KafkaSourceTest {
     assert(query.exception.isEmpty)
   }
 
+  test("get offsets from case insensitive parameters") {
+    for ((optionKey, optionValue, answer) <- Seq(
+      (STARTING_OFFSETS_OPTION_KEY, "earLiEst", EarliestOffsetRangeLimit),
+      (ENDING_OFFSETS_OPTION_KEY, "laTest", LatestOffsetRangeLimit),
+      (STARTING_OFFSETS_OPTION_KEY, """{"topic-A":{"0":23}}""",
+        SpecificOffsetRangeLimit(Map(new TopicPartition("topic-A", 0) -> 23))))) {
+      val offset = getKafkaOffsetRangeLimit(Map(optionKey -> optionValue), optionKey, answer)
+      assert(offset === answer)
+    }
+
+    for ((optionKey, answer) <- Seq(
+      (STARTING_OFFSETS_OPTION_KEY, EarliestOffsetRangeLimit),
+      (ENDING_OFFSETS_OPTION_KEY, LatestOffsetRangeLimit))) {
+      val offset = getKafkaOffsetRangeLimit(Map.empty, optionKey, answer)
+      assert(offset === answer)
+    }
+  }
+
   private def newTopic(): String = s"topic-${topicId.getAndIncrement()}"
 
   private def assignString(topic: String, partitions: Iterable[Int]): String = {