feat: Improve CometHashJoin statistics

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

@@ -694,6 +694,26 @@ case class CometHashJoinExec(
 
   override def hashCode(): Int =
     Objects.hashCode(leftKeys, rightKeys, condition, buildSide, left, right)
+
+  override lazy val metrics: Map[String, SQLMetric] =
+    Map(
+      "build_time" ->
+        SQLMetrics.createNanoTimingMetric(
+          sparkContext,
+          "Total time for collecting build-side of join"),
+      "build_input_batches" ->
+        SQLMetrics.createMetric(sparkContext, "Number of batches consumed by build-side"),
+      "build_input_rows" ->
+        SQLMetrics.createMetric(sparkContext, "Number of rows consumed by build-side"),
+      "build_mem_used" ->
+        SQLMetrics.createSizeMetric(sparkContext, "Memory used by build-side"),
+      "input_batches" ->
+        SQLMetrics.createMetric(sparkContext, "Number of batches consumed by probe-side"),
+      "input_rows" ->
+        SQLMetrics.createMetric(sparkContext, "Number of rows consumed by probe-side"),
+      "output_batches" -> SQLMetrics.createMetric(sparkContext, "Number of batches produced"),
+      "output_rows" -> SQLMetrics.createMetric(sparkContext, "Number of rows produced"),
+      "join_time" -> SQLMetrics.createNanoTimingMetric(sparkContext, "Total time for joining"))
 }
 
 case class CometBroadcastHashJoinExec(

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

@@ -35,7 +35,7 @@ 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, CometSortExec, CometSortMergeJoinExec, CometTakeOrderedAndProjectExec}
+import org.apache.spark.sql.comet.{CometBroadcastExchangeExec, CometCollectLimitExec, CometFilterExec, CometHashAggregateExec, CometHashJoinExec, CometProjectExec, CometRowToColumnarExec, CometScanExec, CometSortExec, 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
@@ -331,6 +331,43 @@ class CometExecSuite extends CometTestBase {
     }
   }
 
+  test("Comet native metrics: HashMergeJoin") {
+    withSQLConf(
+      CometConf.COMET_EXEC_ENABLED.key -> "true",
+      CometConf.COMET_EXEC_ALL_OPERATOR_ENABLED.key -> "true") {
+      withParquetTable((0 until 5).map(i => (i, i + 1)), "t1") {
+        withParquetTable((0 until 5).map(i => (i, i + 1)), "t2") {
+          val df = sql("SELECT /*+ SHUFFLE_HASH(t1) */ * FROM t1 INNER JOIN t2 ON t1._1 = t2._1")
+          df.collect()
+
+          val metrics = find(df.queryExecution.executedPlan) {
+            case _: CometHashJoinExec => true
+            case _ => false
+          }.map(_.metrics).get
+
+          assert(metrics.contains("build_time"))
+          assert(metrics("build_time").value > 1L)
+          assert(metrics.contains("build_input_batches"))
+          assert(metrics("build_input_batches").value == 5L)
+          assert(metrics.contains("build_mem_used"))
+          assert(metrics("build_mem_used").value > 1L)
+          assert(metrics.contains("build_input_rows"))
+          assert(metrics("build_input_rows").value == 5L)
+          assert(metrics.contains("input_batches"))
+          assert(metrics("input_batches").value == 5L)
+          assert(metrics.contains("input_rows"))
+          assert(metrics("input_rows").value == 5L)
+          assert(metrics.contains("output_batches"))
+          assert(metrics("output_batches").value == 5L)
+          assert(metrics.contains("output_rows"))
+          assert(metrics("output_rows").value == 5L)
+          assert(metrics.contains("join_time"))
+          assert(metrics("join_time").value > 1L)
+        }
+      }
+    }
+  }
+
   test(
     "fix: ReusedExchangeExec + CometShuffleExchangeExec under QueryStageExec " +
       "should be CometRoot") {