error handling on quantile values

Author: squito

core/src/main/scala/org/apache/spark/status/api/v1/JsonRootResource.scala

@@ -140,3 +140,16 @@ private[v1] class NotFoundException(msg: String) extends WebApplicationException
       .entity(msg)
       .build()
 )
+
+private[v1] class BadParameterException(msg: String) extends WebApplicationException(
+  new IllegalArgumentException(msg),
+  Response
+    .status(Response.Status.BAD_REQUEST)
+    .entity(msg)
+    .build()
+) {
+  def this(param: String, exp: String, actual: String) = {
+    this("Bad value for parameter \"" + param + "\".  Expected a " + exp + ", got \"" +
+      actual + "\"")
+  }
+}

core/src/main/scala/org/apache/spark/status/api/v1/OneStageResource.scala

@@ -80,9 +80,14 @@ private[v1] class OneStageResource(uiRoot: UIRoot) {
           stageInfo.stageId + ":" + stageInfo.attemptId)
           )
       }
-      //TODO error handling
-      val quantiles = quantileString.split(",").map{_.toDouble}
-      println("quantiles = " + quantiles.mkString(","))
+      val quantiles = quantileString.split(",").map{s =>
+        try {
+          s.toDouble
+        } catch {
+          case nfe: NumberFormatException =>
+            throw new BadParameterException("quantiles", "double", s)
+        }
+      }
       AllStagesResource.taskMetricDistributions(stageUiData.taskData.values, quantiles)
     }
   }