made change from PR 342 for scala 2.12 support and added logic for Spark 3.0.1 support

Author: Bryan Marsh

pom.xml

@@ -19,7 +19,7 @@ limitations under the License.
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.microsoft.azure</groupId>
-    <artifactId>azure-cosmosdb-spark_2.4.0_2.11</artifactId>
+    <artifactId>azure-cosmosdb-spark_3.0.1_2.12</artifactId>
     <packaging>jar</packaging>
     <version>3.3.1</version>
     <name>${project.groupId}:${project.artifactId}</name>
@@ -32,11 +32,11 @@ limitations under the License.
         </license>
     </licenses>
     <properties>
-        <scala.version>2.11.12</scala.version>
-        <scala.binary.version>2.11</scala.binary.version>
+        <scala.version>2.12.10</scala.version>
+        <scala.binary.version>2.12</scala.binary.version>
         <sonar.projectBaseDir>azure-cosmosdb-spark</sonar.projectBaseDir>
         <scala.test.version>3.1.1</scala.test.version>
-        <spark.version>2.4.4</spark.version>
+        <spark.version>3.0.1</spark.version>
         <slf4j.version>1.7.30</slf4j.version>
         <log4j.version>1.2.17</log4j.version>
         <tinkerpop.version>3.2.5</tinkerpop.version>

src/main/scala/com/microsoft/azure/cosmosdb/spark/rdd/CosmosDBRDD.scala

@@ -31,6 +31,7 @@ import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.sources.Filter
 import org.apache.spark.sql.types.StructType
 import org.apache.spark.sql.{DataFrame, Dataset, SparkSession}
+import org.apache.spark.util.TaskCompletionListener
 import org.apache.spark.{Partition, TaskContext}
 
 import scala.collection.mutable
@@ -114,9 +115,11 @@ class CosmosDBRDD(
       case cosmosDBPartition: CosmosDBPartition =>
         logInfo(s"CosmosDBRDD:compute: Start CosmosDBRDD compute task for partition key range id ${cosmosDBPartition.partitionKeyRangeId}")
 
-        context.addTaskCompletionListener((ctx: TaskContext) => {
-          logInfo(s"CosmosDBRDD:compute: CosmosDBRDD compute task completed for partition key range id ${cosmosDBPartition.partitionKeyRangeId}")
-        })
+        val completionListener: TaskCompletionListener = new TaskCompletionListener() {
+          override def onTaskCompletion(context: TaskContext): Unit =
+            logInfo(s"CosmosDBRDD:compute: CosmosDBRDD compute task completed for partition key range id ${cosmosDBPartition.partitionKeyRangeId}")
+        }
+        context.addTaskCompletionListener(completionListener)
 
         new CosmosDBRDDIterator(
           hadoopConfig,

src/main/scala/com/microsoft/azure/cosmosdb/spark/rdd/CosmosDBRDDIterator.scala

@@ -41,6 +41,7 @@ import com.microsoft.azure.documentdb.internal.HttpConstants.SubStatusCodes
 import org.apache.commons.lang3.StringUtils
 import org.apache.spark._
 import org.apache.spark.sql.sources.Filter
+import org.apache.spark.util.TaskCompletionListener
 
 import scala.collection.mutable
 import org.joda.time.DateTimeZone
@@ -437,9 +438,13 @@ class CosmosDBRDDIterator(hadoopConfig: mutable.Map[String, String],
     })
 
     // Register an on-task-completion callback to close the input stream.
-    taskContext.addTaskCompletionListener((_: TaskContext) => {
-      closeIfNeeded()
-    })
+    val taskCompletionListerner = new TaskCompletionListener() {
+      override def onTaskCompletion(context: TaskContext): Unit = {
+        closeIfNeeded()
+      }
+    }
+
+    taskContext.addTaskCompletionListener(taskCompletionListerner)
 
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