Added comments

src/it/scala/com/qubole/spark/hiveacid/ReadSuite.scala

@@ -26,7 +26,7 @@ import org.scalatest._
 
 import scala.util.control.NonFatal
 
-@Ignore
+//@Ignore
 class ReadSuite extends FunSuite with BeforeAndAfterEach with BeforeAndAfterAll {
 
   val log: Logger = LogManager.getLogger(this.getClass)

src/main/scala/com/qubole/spark/hiveacid/HiveAcidDataSourceV2Reader.scala

@@ -60,6 +60,7 @@ class HiveAcidDataSourceV2Reader
     if (dbName != null) {
       hiveAcidMetadata = HiveAcidMetadata.fromSparkSession(sparkSession, dbName + "." + tblName)
     } else {
+      // If db name is null, default db is chosen.
       hiveAcidMetadata = HiveAcidMetadata.fromSparkSession(sparkSession, tblName)
     }
 

src/main/scala/com/qubole/spark/hiveacid/reader/hive/HiveAcidReader.scala

@@ -118,19 +118,20 @@ extends CastSupport with Reader with Logging {
       hiveAcidMetadata.hTable.getParameters,
       colNames, colTypes) _
 
-    //TODO : Need to cahce it with some unique id.
+    //TODO : Need to cache it with some unique id.
     val jobConf = new JobConf(_broadcastedHadoopConf.value.value)
     initializeJobConfFunc(jobConf)
 
+    //TODO:Can this be done parallely in multiple threads?
     val partitionArray = new java.util.ArrayList[InputPartition[ColumnarBatch]]
     val inputSplits  = HiveAcidCommon.getInputSplits(jobConf, validWriteIds, 0,
       hiveAcidMetadata.isFullAcidTable, ifc)
-    val reqFileds = hiveAcidMetadata.tableSchema.fields.filter(field =>
+    val reqFields = hiveAcidMetadata.tableSchema.fields.filter(field =>
       readerOptions.requiredNonPartitionedColumns.contains(field.name))
-    for (i <- 0 until inputSplits.size) {
+    for (i <- inputSplits.indices) {
       partitionArray.add(new HiveAcidInputPartitionV2(inputSplits(i).asInstanceOf[HiveAcidPartition],
         sparkSession.sparkContext.broadcast(new SerializableConfiguration(jobConf)),
-        partitionValues, reqFileds, hiveAcidMetadata.partitionSchema, hiveAcidMetadata.isFullAcidTable))
+        partitionValues, reqFields, hiveAcidMetadata.partitionSchema, hiveAcidMetadata.isFullAcidTable))
       logInfo("getPartitions : Input split: " + inputSplits(i))
     }
     partitionArray
@@ -215,14 +216,12 @@ extends CastSupport with Reader with Logging {
 
       val mutableRow = new SpecificInternalRow(hiveAcidMetadata.partitionSchema)
 
-      // Splits all attributes into two groups, partition key attributes and those
-      // that are not. Attached indices indicate the position of each attribute in
-      // the output schema.
-      val (partitionKeyAttrs, nonPartitionKeyAttrs) =
-      readerOptions.requiredAttributes.zipWithIndex.partition { case (attr, _) =>
+      val partitionKeyAttrs =
+      readerOptions.requiredAttributes.zipWithIndex.filter { attr =>
         readerOptions.partitionAttributes.contains(attr)
       }
 
+      //TODO : The partition values can be filled directly using hive acid batch reader.
       def fillPartitionKeys(rawPartValues: Array[String], row: InternalRow): Unit = {
         var offset = 0
         partitionKeyAttrs.foreach { case (attr, ordinal) =>

src/main/scala/com/qubole/spark/hiveacid/reader/v2/OrcColumnVector.java → src/main/scala/com/qubole/spark/hiveacid/reader/v2/HiveAcidColumnVector.java

@@ -36,9 +36,9 @@
 /**
  * A column vector class wrapping Hive's ColumnVector. Because Spark ColumnarBatch only accepts
  * Spark's vectorized.ColumnVector, this column vector is used to adapt Hive ColumnVector with
- * Spark ColumnarVector.
+ * Spark ColumnarVector. This class is a copy of spark ColumnVector which is declared private.
  */
-public class OrcColumnVector extends org.apache.spark.sql.vectorized.ColumnVector {
+public class HiveAcidColumnVector extends org.apache.spark.sql.vectorized.ColumnVector {
   private ColumnVector baseData;
   private LongColumnVector longData;
   private DoubleColumnVector doubleData;
@@ -49,7 +49,7 @@ public class OrcColumnVector extends org.apache.spark.sql.vectorized.ColumnVecto
 
   private int batchSize;
 
-  OrcColumnVector(DataType type, ColumnVector vector) {
+  HiveAcidColumnVector(DataType type, ColumnVector vector) {
     super(type);
 
     if (type instanceof TimestampType) {

src/main/scala/com/qubole/spark/hiveacid/reader/v2/HiveAcidInputPartitionReaderV2.scala

@@ -35,9 +35,8 @@ private[v2] class HiveAcidInputPartitionReaderV2(split: HiveAcidPartition,
                                                  isFullAcidTable: Boolean)
         extends InputPartitionReader[ColumnarBatch] {
   //TODO : Need to get a unique id to cache the jobConf.
-  private val jobConf : JobConf = new JobConf(broadcastedConf.value.value)
-  private val sparkOrcColReader : OrcColumnarBatchReader =
-    new OrcColumnarBatchReader(1024)
+  private val jobConf = new JobConf(broadcastedConf.value.value)
+  private val orcColumnarBatchReader = new OrcColumnarBatchReader(1024)
 
   private def initReader() : Unit = {
     // Get the reader schema using the column names and types set in hive conf.
@@ -63,26 +62,27 @@ private[v2] class HiveAcidInputPartitionReaderV2(split: HiveAcidPartition,
     // Register the listener for closing the reader before init is done.
     val attemptId = new TaskAttemptID(new TaskID(new JobID(), TaskType.MAP, 0), 0)
     val taskAttemptContext = new org.apache.hadoop.mapred.TaskAttemptContextImpl(jobConf, attemptId)
-    val iter = new org.apache.spark.sql.execution.datasources.RecordReaderIterator(sparkOrcColReader)
+    val iter = new org.apache.spark.sql.execution.datasources.RecordReaderIterator(orcColumnarBatchReader)
     Option(TaskContext.get()).foreach(_.addTaskCompletionListener[Unit](_ => iter.close()))
 
-    sparkOrcColReader.initialize(fileSplit, taskAttemptContext)
-    sparkOrcColReader.initBatch(readerLocal.getSchema, requestedColIds,
+    //TODO: Need to generalize it for supporting other kind of file format.
+    orcColumnarBatchReader.initialize(fileSplit, taskAttemptContext)
+    orcColumnarBatchReader.initBatch(readerLocal.getSchema, requestedColIds,
       requiredFields, partitionSchema, partitionValues, isFullAcidTable && !fileSplit.isOriginal)
   }
   initReader()
 
   @throws(classOf[IOException])
   override def next() : Boolean = {
-    sparkOrcColReader.nextKeyValue()
+    orcColumnarBatchReader.nextKeyValue()
   }
 
   override def get () : ColumnarBatch = {
-    sparkOrcColReader.getCurrentValue
+    orcColumnarBatchReader.getCurrentValue
   }
 
   @throws(classOf[IOException])
   override def close() : Unit = {
-    sparkOrcColReader.close()
+    orcColumnarBatchReader.close()
   }
 }