Address PR comments

Signed-off-by: Chen Dai <[email protected]>

flint-spark-integration/src/main/scala/org/opensearch/flint/spark/FlintSparkIndexMonitor.scala

@@ -126,7 +126,12 @@ class FlintSparkIndexMonitor(
     } else {
       logInfo(s"Index monitor for [$indexName] not found.")
 
-      // Streaming job may exit early. Try to find Flint index name in monitor list.
+      /*
+       * Streaming job exits early. Try to find Flint index name in monitor list.
+       * Assuming: 1) there are at most 1 entry in the list, otherwise index name
+       * must be given upon this method call; 2) this await API must be called for
+       * auto refresh index, otherwise index state will be updated mistakenly.
+       */
       val name = FlintSparkIndexMonitor.indexMonitorTracker.keys.headOption
       if (name.isDefined) {
         logInfo(s"Found index name in index monitor task list: ${name.get}")

spark-sql-application/src/main/scala/org/apache/spark/sql/JobOperator.scala

@@ -88,11 +88,11 @@ case class JobOperator(
     }
 
     try {
-      // Wait for streaming job complete if no error and there is streaming job running
+      // Wait for streaming job complete if no error
       if (!exceptionThrown && streaming) {
         // Clean Spark shuffle data after each microBatch.
         spark.streams.addListener(new ShuffleCleaner(spark))
-        // Await streaming job thread to finish before the main thread terminates
+        // Await index monitor before the main thread terminates
         new FlintSpark(spark).flintIndexMonitor.awaitMonitor()
       } else {
         logInfo(s"""