[ML-3775] Add "benchmarkId" to BenchmarkResult (#146)

Add "benchmarkId" to BenchmarkResult, which is based on the benchmark name and a hashed value of params.

src/main/scala/com/databricks/spark/sql/perf/mllib/MLPipelineStageBenchmarkable.scala

@@ -95,13 +95,16 @@ class MLPipelineStageBenchmarkable(
       }
 
       val mlMetrics = Array(metricTrainingTime, metricTraining, metricTestTime, metricTest)
+      val paramsMap = params.toMap
+      val benchmarkId = name.split('.').last + "_" + paramsMap.hashCode.abs
 
       BenchmarkResult(
         name = name,
         mode = executionMode.toString,
-        parameters = params.toMap,
+        parameters = paramsMap,
         executionTime = Some(trainingTime.toMillis),
-        mlResult = Some(mlMetrics))
+        mlResult = Some(mlMetrics),
+        benchmarkId = Some(benchmarkId))
     } catch {
       case e: Exception =>
         BenchmarkResult(

src/main/scala/com/databricks/spark/sql/perf/results.scala

@@ -67,6 +67,12 @@ case class BenchmarkConfiguration(
  *               For example, it can be the number of rows generated by this query or
  *               the sum of hash values of rows generated by this query.
  * @param breakDown The breakdown results of the query plan tree.
+ * @param queryExecution The query execution plan.
+ * @param failure The failure message.
+ * @param mlResult The result metrics specific to MLlib.
+ * @param benchmarkId An optional ID to identify a series of benchmark runs.
+ *                    In ML, this is generated based on the benchmark name and
+ *                    the hash value of params.
  */
 case class BenchmarkResult(
     name: String,
@@ -83,7 +89,8 @@ case class BenchmarkResult(
     breakDown: Seq[BreakdownResult] = Nil,
     queryExecution: Option[String] = None,
     failure: Option[Failure] = None,
-    mlResult: Option[Array[MLMetric]] = None)
+    mlResult: Option[Array[MLMetric]] = None,
+    benchmarkId: Option[String] = None)
 
 /**
  * The execution time of a subtree of the query plan tree of a specific query.
@@ -240,4 +247,4 @@ case class MLMetric(
 
 object MLMetric {
   val Invalid = MLMetric("Invalid", 0.0, false)
-}
+}