[SPARK-11253][SQL] reset all accumulators in physical operators before execute an action

sql/core/src/main/scala/org/apache/spark/sql/DataFrame.scala

@@ -1963,6 +1963,9 @@ class DataFrame private[sql](
    */
   private def withCallback[T](name: String, df: DataFrame)(action: DataFrame => T) = {
     try {
+      df.queryExecution.executedPlan.foreach { plan =>
+        plan.metrics.valuesIterator.foreach(_.reset())
+      }
       val start = System.nanoTime()
       val result = action(df)
       val end = System.nanoTime()

sql/core/src/main/scala/org/apache/spark/sql/execution/metric/SQLMetrics.scala

@@ -28,7 +28,12 @@ import org.apache.spark.{Accumulable, AccumulableParam, SparkContext}
  */
 private[sql] abstract class SQLMetric[R <: SQLMetricValue[T], T](
     name: String, val param: SQLMetricParam[R, T])
-  extends Accumulable[R, T](param.zero, param, Some(name), true)
+  extends Accumulable[R, T](param.zero, param, Some(name), true) {
+
+  def reset(): Unit = {
+    this.value = param.zero
+  }
+}
 
 /**
  * Create a layer for specialized metric. We cannot add `@specialized` to

sql/core/src/test/scala/org/apache/spark/sql/util/DataFrameCallbackSuite.scala

@@ -80,4 +80,24 @@ class DataFrameCallbackSuite extends QueryTest with SharedSQLContext {
     assert(metrics(0)._2.analyzed.isInstanceOf[Project])
     assert(metrics(0)._3.getMessage == e.getMessage)
   }
+
+  test("get metrics by callback") {
+    val metrics = ArrayBuffer.empty[Long]
+    val listener = new QueryExecutionListener {
+      // Only test successful case here, so no need to implement `onFailure`
+      override def onFailure(funcName: String, qe: QueryExecution, exception: Exception): Unit = {}
+
+      override def onSuccess(funcName: String, qe: QueryExecution, duration: Long): Unit = {
+        metrics += qe.executedPlan.longMetric("numInputRows").value.value
+      }
+    }
+    sqlContext.listenerManager.register(listener)
+
+    Seq(1 -> "a").toDF("i", "j").groupBy("i").count().collect()
+    Seq(1 -> "a", 2 -> "a").toDF("i", "j").groupBy("i").count().collect()
+
+    assert(metrics.length == 2)
+    assert(metrics(0) == 1)
+    assert(metrics(1) == 2)
+  }
 }