From 1f99bb842773e8852afded85d35586bbf13fa825 Mon Sep 17 00:00:00 2001
From: Matthew Khouzam <matthew.khouzam@ericsson.com>
Date: Tue, 19 Nov 2024 10:47:23 -0500
Subject: [PATCH] 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 <matthew.khouzam@ericsson.com>
---
 .../tmf/ui/views/histogram/Histogram.java     |  9 +++++-
 .../views/histogram/HistogramScaledData.java  | 30 +++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/Histogram.java b/tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/Histogram.java
index 6652409ffe..975a09cb2e 100644
--- a/tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/Histogram.java
+++ b/tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/Histogram.java
@@ -74,6 +74,8 @@
 import org.eclipse.tracecompass.tmf.ui.widgets.timegraph.widgets.TimeGraphColorScheme;
 import org.eclipse.tracecompass.tmf.ui.widgets.timegraph.widgets.TimeGraphScale;
 
+import com.google.common.base.Objects;
+
 /**
  * Re-usable histogram widget.
  *
@@ -678,7 +680,12 @@ public void modelUpdated() {
                         return;
                     }
                     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 (TraceCompassLogUtils.FlowScopeLog fs1 = new TraceCompassLogUtils.FlowScopeLogBuilder(LOGGER, Level.FINER, "Histogram:ui").setParentScope(fs).build()) { //$NON-NLS-1$
                         synchronized (fDataModel) {
                             if (fScaledData != null) {
diff --git a/tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/HistogramScaledData.java b/tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/HistogramScaledData.java
index 9b232de374..8908e55961 100644
--- a/tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/views/histogram/HistogramScaledData.java
+++ b/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;
+    }
 }