feat: Improve CometSortMergeJoin statistics

spark/src/main/scala/org/apache/spark/sql/comet/operators.scala

@@ -727,6 +727,16 @@ case class CometSortMergeJoinExec(
 
   override def hashCode(): Int =
     Objects.hashCode(leftKeys, rightKeys, condition, left, right)
+
+  override lazy val metrics: Map[String, SQLMetric] =
+    Map(
+      "input_batches" -> SQLMetrics.createMetric(sparkContext, "Number of batches consumed"),
+      "input_rows" -> SQLMetrics.createMetric(sparkContext, "Number of rows consumed"),
+      "output_batches" -> SQLMetrics.createMetric(sparkContext, "Number of batches produced"),
+      "output_rows" -> SQLMetrics.createMetric(sparkContext, "Number of rows produced"),
+      "peak_mem_used" ->
+        SQLMetrics.createSizeMetric(sparkContext, "Peak memory used for buffered data"),
+      "join_time" -> SQLMetrics.createNanoTimingMetric(sparkContext, "Total time for joining"))
 }
 
 case class CometScanWrapper(override val nativeOp: Operator, override val originalPlan: SparkPlan)

spark/src/test/scala/org/apache/comet/exec/CometExecSuite.scala

@@ -34,7 +34,7 @@ import org.apache.spark.sql.catalyst.TableIdentifier
 import org.apache.spark.sql.catalyst.catalog.{BucketSpec, CatalogStatistics, CatalogTable}
 import org.apache.spark.sql.catalyst.expressions.Hex
 import org.apache.spark.sql.catalyst.expressions.aggregate.AggregateMode
-import org.apache.spark.sql.comet.{CometBroadcastExchangeExec, CometCollectLimitExec, CometFilterExec, CometHashAggregateExec, CometProjectExec, CometRowToColumnarExec, CometScanExec, CometTakeOrderedAndProjectExec}
+import org.apache.spark.sql.comet.{CometBroadcastExchangeExec, CometCollectLimitExec, CometFilterExec, CometHashAggregateExec, CometProjectExec, CometRowToColumnarExec, CometScanExec, CometSortMergeJoinExec, CometTakeOrderedAndProjectExec}
 import org.apache.spark.sql.comet.execution.shuffle.{CometColumnarShuffle, CometShuffleExchangeExec}
 import org.apache.spark.sql.execution.{CollectLimitExec, ProjectExec, SQLExecution, UnionExec}
 import org.apache.spark.sql.execution.exchange.BroadcastExchangeExec
@@ -252,6 +252,39 @@ class CometExecSuite extends CometTestBase {
     }
   }
 
+  test("Comet native metrics: SortMergeJoin") {
+    withSQLConf(
+      CometConf.COMET_EXEC_ENABLED.key -> "true",
+      CometConf.COMET_EXEC_ALL_OPERATOR_ENABLED.key -> "true",
+      "spark.sql.autoBroadcastJoinThreshold" -> "0",
+      "spark.sql.join.preferSortMergeJoin" -> "true") {
+      withParquetTable((0 until 5).map(i => (i, i + 1)), "tbl1") {
+        withParquetTable((0 until 5).map(i => (i, i + 1)), "tbl2") {
+          val df = sql("SELECT * FROM tbl1 INNER JOIN tbl2 ON tbl1._1 = tbl2._1")
+          df.collect()
+
+          val metrics = find(df.queryExecution.executedPlan) {
+            case _: CometSortMergeJoinExec => true
+            case _ => false
+          }.map(_.metrics).get
+
+          assert(metrics.contains("input_batches"))
+          assert(metrics("input_batches").value == 2L)
+          assert(metrics.contains("input_rows"))
+          assert(metrics("input_rows").value == 10L)
+          assert(metrics.contains("output_batches"))
+          assert(metrics("output_batches").value == 1L)
+          assert(metrics.contains("output_rows"))
+          assert(metrics("output_rows").value == 5L)
+          assert(metrics.contains("peak_mem_used"))
+          assert(metrics("peak_mem_used").value > 1L)
+          assert(metrics.contains("join_time"))
+          assert(metrics("join_time").value > 1L)
+        }
+      }
+    }
+  }
+
   test(
     "fix: ReusedExchangeExec + CometShuffleExchangeExec under QueryStageExec " +
       "should be CometRoot") {