[SPARK-25581][SQL] Rename method benchmark as runBenchmarkSuite in BenchmarkBase

## What changes were proposed in this pull request?

Rename method `benchmark` in `BenchmarkBase` as `runBenchmarkSuite `. Also add comments.
Currently the method name `benchmark` is a bit confusing. Also the name is the same as instances of `Benchmark`:

f246813afb/sql/hive/src/test/scala/org/apache/spark/sql/hive/orc/OrcReadBenchmark.scala (L330-L339)

## How was this patch tested?

Unit test.

Closes #22599 from gengliangwang/renameBenchmarkSuite.

Authored-by: Gengliang Wang <gengliang.wang@databricks.com>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>

core/src/test/scala/org/apache/spark/benchmark/BenchmarkBase.scala

@@ -25,7 +25,12 @@ import java.io.{File, FileOutputStream, OutputStream}
 abstract class BenchmarkBase {
   var output: Option[OutputStream] = None
 
-  def benchmark(): Unit
+  /**
+   * Main process of the whole benchmark.
+   * Implementations of this method are supposed to use the wrapper method `runBenchmark`
+   * for each benchmark scenario.
+   */
+  def runBenchmarkSuite(): Unit
 
   final def runBenchmark(benchmarkName: String)(func: => Any): Unit = {
     val separator = "=" * 96
@@ -46,7 +51,7 @@ abstract class BenchmarkBase {
       output = Some(new FileOutputStream(file))
     }
 
-    benchmark()
+    runBenchmarkSuite()
 
     output.foreach { o =>
       if (o != null) {

mllib/src/test/scala/org/apache/spark/mllib/linalg/UDTSerializationBenchmark.scala

@@ -32,7 +32,7 @@ import org.apache.spark.sql.catalyst.encoders.ExpressionEncoder
  */
 object UDTSerializationBenchmark extends BenchmarkBase {
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
 
     runBenchmark("VectorUDT de/serialization") {
       val iters = 1e2.toInt

sql/catalyst/src/test/scala/org/apache/spark/sql/UnsafeProjectionBenchmark.scala

@@ -41,7 +41,7 @@ object UnsafeProjectionBenchmark extends BenchmarkBase {
     (1 to numRows).map(_ => encoder.toRow(generator().asInstanceOf[Row]).copy()).toArray
   }
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
     runBenchmark("unsafe projection") {
       val iters = 1024 * 16
       val numRows = 1024 * 16

sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/AggregateBenchmark.scala

@@ -44,7 +44,7 @@ import org.apache.spark.unsafe.map.BytesToBytesMap
  */
 object AggregateBenchmark extends SqlBasedBenchmark {
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
     runBenchmark("aggregate without grouping") {
       val N = 500L << 22
       codegenBenchmark("agg w/o group", N) {

sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/FilterPushdownBenchmark.scala

@@ -198,7 +198,7 @@ object FilterPushdownBenchmark extends BenchmarkBase with SQLHelper {
     }
   }
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
     runBenchmark("Pushdown for many distinct value case") {
       withTempPath { dir =>
         withTempTable("orcTable", "parquetTable") {

sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/PrimitiveArrayBenchmark.scala

@@ -36,7 +36,7 @@ object PrimitiveArrayBenchmark extends BenchmarkBase {
     .config("spark.sql.autoBroadcastJoinThreshold", 1)
     .getOrCreate()
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
     runBenchmark("Write primitive arrays in dataset") {
       writeDatasetArray(4)
     }

sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/SortBenchmark.scala

@@ -119,7 +119,7 @@ object SortBenchmark extends BenchmarkBase {
     benchmark.run()
   }
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
     runBenchmark("radix sort") {
       sortBenchmark()
     }

sql/core/src/test/scala/org/apache/spark/sql/execution/columnar/compression/CompressionSchemeBenchmark.scala

@@ -233,7 +233,7 @@ object CompressionSchemeBenchmark extends BenchmarkBase with AllCompressionSchem
     runDecodeBenchmark("STRING Decode", iters, count, STRING, testData)
   }
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
     runBenchmark("Compression Scheme Benchmark") {
       bitEncodingBenchmark(1024)
       shortEncodingBenchmark(1024)

sql/core/src/test/scala/org/apache/spark/sql/execution/vectorized/ColumnarBatchBenchmark.scala

@@ -443,7 +443,7 @@ object ColumnarBatchBenchmark extends BenchmarkBase {
     benchmark.run
   }
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
     runBenchmark("Int Read/Write") {
       intAccess(1024 * 40)
     }

sql/hive/src/test/scala/org/apache/spark/sql/hive/orc/OrcReadBenchmark.scala

@@ -336,7 +336,7 @@ object OrcReadBenchmark extends BenchmarkBase with SQLHelper {
     }
   }
 
-  override def benchmark(): Unit = {
+  override def runBenchmarkSuite(): Unit = {
     runBenchmark("SQL Single Numeric Column Scan") {
       Seq(ByteType, ShortType, IntegerType, LongType, FloatType, DoubleType).foreach { dataType =>
         numericScanBenchmark(1024 * 1024 * 15, dataType)