[SPARK-7658] [STREAMING] [WEBUI] Update the mouse behaviors for the timeline graphs

1. If the user click one point of a batch, scroll down to the corresponding batch row and highlight it. And recovery the batch row after 3 seconds if necessary.

2. Add "#batches" in the histogram graphs.

![screen shot 2015-05-14 at 7 36 19 pm](https://cloud.githubusercontent.com/assets/1000778/7646108/84f4a014-fa73-11e4-8c13-1903d267e60f.png)

![screen shot 2015-05-14 at 7 36 53 pm](https://cloud.githubusercontent.com/assets/1000778/7646109/8b11154a-fa73-11e4-820b-8ece9fa6ee3e.png)

![screen shot 2015-05-14 at 7 36 34 pm](https://cloud.githubusercontent.com/assets/1000778/7646111/93828272-fa73-11e4-89f8-580670144d3c.png)

Author: zsxwing <zsxwing@gmail.com>

Closes #6168 from zsxwing/SPARK-7658 and squashes the following commits:

c242b00 [zsxwing] Change 5 seconds to 3 seconds
31fd0aa [zsxwing] Remove the mouseover highlight feature
06c6f6f [zsxwing] Merge branch 'master' into SPARK-7658
2eaff06 [zsxwing] Merge branch 'master' into SPARK-7658
108d56c [zsxwing] Update the mouse behaviors for the timeline graphs

streaming/src/main/resources/org/apache/spark/streaming/ui/static/streaming-page.css

@@ -60,3 +60,7 @@
 span.expand-input-rate {
   cursor: pointer;
 }
+
+tr.batch-table-cell-highlight > td {
+  background-color: #D6FFE4 !important;
+}

streaming/src/main/resources/org/apache/spark/streaming/ui/static/streaming-page.js

@@ -146,6 +146,12 @@ function drawTimeline(id, data, minX, maxX, minY, maxY, unitY, batchInterval) {
         .attr("class", "line")
         .attr("d", line);
 
+    // If the user click one point in the graphs, jump to the batch row and highlight it. And
+    // recovery the batch row after 3 seconds if necessary.
+    // We need to remember the last clicked batch so that we can recovery it.
+    var lastClickedBatch = null;
+    var lastTimeout = null;
+
     // Add points to the line. However, we make it invisible at first. But when the user moves mouse
     // over a point, it will be displayed with its detail.
     svg.selectAll(".point")
@@ -154,6 +160,7 @@ function drawTimeline(id, data, minX, maxX, minY, maxY, unitY, batchInterval) {
             .attr("stroke", "white") // white and opacity = 0 make it invisible
             .attr("fill", "white")
             .attr("opacity", "0")
+            .style("cursor", "pointer")
             .attr("cx", function(d) { return x(d.x); })
             .attr("cy", function(d) { return y(d.y); })
             .attr("r", function(d) { return 3; })
@@ -175,7 +182,29 @@ function drawTimeline(id, data, minX, maxX, minY, maxY, unitY, batchInterval) {
                     .attr("opacity", "0");
             })
             .on("click", function(d) {
-                window.location.href = "batch/?id=" + d.x;
+                if (lastTimeout != null) {
+                    window.clearTimeout(lastTimeout);
+                }
+                if (lastClickedBatch != null) {
+                    clearBatchRow(lastClickedBatch);
+                    lastClickedBatch = null;
+                }
+                lastClickedBatch = d.x;
+                highlightBatchRow(lastClickedBatch)
+                lastTimeout = window.setTimeout(function () {
+                    lastTimeout = null;
+                    if (lastClickedBatch != null) {
+                        clearBatchRow(lastClickedBatch);
+                        lastClickedBatch = null;
+                    }
+                }, 3000); // Clean up after 3 seconds
+
+                var batchSelector = $("#batch-" + d.x);
+                var topOffset = batchSelector.offset().top - 15;
+                if (topOffset < 0) {
+                    topOffset = 0;
+                }
+                $('html,body').animate({scrollTop: topOffset}, 200);
             });
 }
 
@@ -218,6 +247,9 @@ function drawHistogram(id, values, minY, maxY, unitY, batchInterval) {
     svg.append("g")
         .attr("class", "x axis")
         .call(xAxis)
+        .append("text")
+            .attr("transform", "translate(" + (margin.left + width - 40) + ", 15)")
+            .text("#batches");
 
     svg.append("g")
         .attr("class", "y axis")
@@ -279,3 +311,11 @@ $(function() {
         $(this).find('.expand-input-rate-arrow').toggleClass('arrow-open').toggleClass('arrow-closed');
     }
 });
+
+function highlightBatchRow(batch) {
+    $("#batch-" + batch).parent().addClass("batch-table-cell-highlight");
+}
+
+function clearBatchRow(batch) {
+    $("#batch-" + batch).parent().removeClass("batch-table-cell-highlight");
+}

streaming/src/main/scala/org/apache/spark/streaming/ui/AllBatchesTable.scala

@@ -44,8 +44,9 @@ private[ui] abstract class BatchTableBase(tableId: String, batchInterval: Long)
     val formattedSchedulingDelay = schedulingDelay.map(SparkUIUtils.formatDuration).getOrElse("-")
     val processingTime = batch.processingDelay
     val formattedProcessingTime = processingTime.map(SparkUIUtils.formatDuration).getOrElse("-")
+    val batchTimeId = s"batch-$batchTime"
 
-    <td sorttable_customkey={batchTime.toString}>
+    <td id={batchTimeId} sorttable_customkey={batchTime.toString}>
       <a href={s"batch?id=$batchTime"}>
         {formattedBatchTime}
       </a>