tmf.ui: Add early exit to Histogram

Speed up histogram by not redrawing when the data is unchanged.

Change-Id: Iea05f628da6e1baea4fd0be3b6071f363099c9bb
Signed-off-by: Matthew Khouzam <[email protected]>

Author: MatthewKhouzam

tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/Histogram.java

@@ -74,6 +74,8 @@
 import org.eclipse.tracecompass.traceeventlogger.LogUtils;
 import org.eclipse.tracecompass.traceeventlogger.LogUtils.ScopeLog;
 
+import com.google.common.base.Objects;
+
 /**
  * Re-usable histogram widget.
  *
@@ -679,7 +681,11 @@ public void modelUpdated() {
                     }
                     try (LogUtils.FlowScopeLog fs1 = new LogUtils.FlowScopeLogBuilder(LOGGER, Level.FINER, "Histogram:scaleData").setParentScope(fs).build()) { //$NON-NLS-1$
                         fDataModel.setSelection(fSelectionBegin, fSelectionEnd);
-                        fScaledData = fDataModel.scaleTo(canvasWidth, canvasHeight, 1);
+                        HistogramScaledData scaledData = fDataModel.scaleTo(canvasWidth, canvasHeight, 1);
+                        if (Objects.equal(scaledData, fScaledData)) {
+                            return;
+                        }
+                        fScaledData = scaledData;
                     }
                     try (LogUtils.FlowScopeLog fs1 = new LogUtils.FlowScopeLogBuilder(LOGGER, Level.FINER, "Histogram:redraw").setParentScope(fs).build()) { //$NON-NLS-1$
                         synchronized (fDataModel) {

tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/HistogramScaledData.java

@@ -20,6 +20,7 @@
 package org.eclipse.tracecompass.tmf.ui.views.histogram;
 
 import java.util.Arrays;
+import java.util.Objects;
 
 /**
  * Convenience class/struct for scaled histogram data.
@@ -232,4 +233,33 @@ private int getOffsetIndex(int index) {
     public long getBucketEndTime(int index) {
         return getBucketStartTime(index + 1);
     }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + Arrays.hashCode(fData);
+        result = prime * result + Arrays.hashCode(fLostEventsData);
+        result = prime * result
+                + Objects.hash(fBarWidth, fBucketDuration, fFirstBucketTime, fFirstEventTime, fHeight, fLastBucket, fMaxCombinedValue, fMaxValue, fScalingFactor, fScalingFactorCombined, fSelectionBeginBucket, fSelectionEndBucket, fWidth);
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        HistogramScaledData other = (HistogramScaledData) obj;
+        return fBarWidth == other.fBarWidth && Double.doubleToLongBits(fBucketDuration) == Double.doubleToLongBits(other.fBucketDuration) && Arrays.equals(fData, other.fData) && fFirstBucketTime == other.fFirstBucketTime
+                && fFirstEventTime == other.fFirstEventTime && fHeight == other.fHeight && fLastBucket == other.fLastBucket && Arrays.equals(fLostEventsData, other.fLostEventsData) && fMaxCombinedValue == other.fMaxCombinedValue
+                && fMaxValue == other.fMaxValue && Double.doubleToLongBits(fScalingFactor) == Double.doubleToLongBits(other.fScalingFactor) && Double.doubleToLongBits(fScalingFactorCombined) == Double.doubleToLongBits(other.fScalingFactorCombined)
+                && fSelectionBeginBucket == other.fSelectionBeginBucket && fSelectionEndBucket == other.fSelectionEndBucket && fWidth == other.fWidth;
+    }
 }