From dfb62926008e85310bc05cbf6b132cfb98662173 Mon Sep 17 00:00:00 2001
From: Linas Medziunas <linas.medziunas@gmail.com>
Date: Thu, 28 Sep 2023 09:06:54 +0300
Subject: [PATCH] Compare FloatHistogram.[Zero]Count float values as binary

Signed-off-by: Linas Medziunas <linas.medziunas@gmail.com>
---
 model/histogram/float_histogram.go      |  3 ++-
 model/histogram/float_histogram_test.go | 36 +++++++++++++++++++++++++
 model/histogram/histogram_test.go       | 19 +++++++++----
 3 files changed, 52 insertions(+), 6 deletions(-)

diff --git a/model/histogram/float_histogram.go b/model/histogram/float_histogram.go
index 6272b66831..54ff5d4df0 100644
--- a/model/histogram/float_histogram.go
+++ b/model/histogram/float_histogram.go
@@ -313,7 +313,8 @@ func (h *FloatHistogram) Equals(h2 *FloatHistogram) bool {
 	}
 
 	if h.Schema != h2.Schema || h.ZeroThreshold != h2.ZeroThreshold ||
-		h.ZeroCount != h2.ZeroCount || h.Count != h2.Count ||
+		math.Float64bits(h.ZeroCount) != math.Float64bits(h2.ZeroCount) ||
+		math.Float64bits(h.Count) != math.Float64bits(h2.Count) ||
 		math.Float64bits(h.Sum) != math.Float64bits(h2.Sum) {
 		return false
 	}
diff --git a/model/histogram/float_histogram_test.go b/model/histogram/float_histogram_test.go
index 0b712be438..61e8fc515c 100644
--- a/model/histogram/float_histogram_test.go
+++ b/model/histogram/float_histogram_test.go
@@ -2291,3 +2291,39 @@ func TestFloatBucketIteratorTargetSchema(t *testing.T) {
 	}
 	require.False(t, it.Next(), "negative iterator not exhausted")
 }
+
+// TestFloatHistogramEquals tests FloatHistogram with float-specific cases that
+// cannot be covered by TestHistogramEquals.
+func TestFloatHistogramEquals(t *testing.T) {
+	h1 := FloatHistogram{
+		Schema:        3,
+		Count:         2.2,
+		Sum:           9.7,
+		ZeroThreshold: 0.1,
+		ZeroCount:     1.1,
+	}
+
+	equals := func(h1, h2 FloatHistogram) {
+		require.True(t, h1.Equals(&h2))
+		require.True(t, h2.Equals(&h1))
+	}
+	notEquals := func(h1, h2 FloatHistogram) {
+		require.False(t, h1.Equals(&h2))
+		require.False(t, h2.Equals(&h1))
+	}
+
+	h2 := h1.Copy()
+	equals(h1, *h2)
+
+	// Count is NaN (but not a StaleNaN).
+	hCountNaN := h1.Copy()
+	hCountNaN.Count = math.NaN()
+	notEquals(h1, *hCountNaN)
+	equals(*hCountNaN, *hCountNaN)
+
+	// ZeroCount is NaN (but not a StaleNaN).
+	hZeroCountNaN := h1.Copy()
+	hZeroCountNaN.ZeroCount = math.NaN()
+	notEquals(h1, *hZeroCountNaN)
+	equals(*hZeroCountNaN, *hZeroCountNaN)
+}
diff --git a/model/histogram/histogram_test.go b/model/histogram/histogram_test.go
index 2af90501e5..23fb1779ea 100644
--- a/model/histogram/histogram_test.go
+++ b/model/histogram/histogram_test.go
@@ -540,11 +540,20 @@ func TestHistogramEquals(t *testing.T) {
 	h2.NegativeBuckets = append(h2.NegativeBuckets, 1)
 	notEquals(h1, *h2)
 
-	// StaleNaN.
-	h2 = h1.Copy()
-	h2.Sum = math.Float64frombits(value.StaleNaN)
-	notEquals(h1, *h2)
-	equals(*h2, *h2)
+	// Sum is StaleNaN.
+	hStale := h1.Copy()
+	hStale.Sum = math.Float64frombits(value.StaleNaN)
+	notEquals(h1, *hStale)
+	equals(*hStale, *hStale)
+
+	// Sum is NaN (but not a StaleNaN).
+	hNaN := h1.Copy()
+	hNaN.Sum = math.NaN()
+	notEquals(h1, *hNaN)
+	equals(*hNaN, *hNaN)
+
+	// Sum StaleNaN vs regular NaN.
+	notEquals(*hStale, *hNaN)
 }
 
 func TestHistogramCompact(t *testing.T) {