remove wrong rehash function

Yiling-J · Oct 27, 2024 · c4b1967 · c4b1967
1 parent 25d3ce5
commit c4b1967
Show file tree

Hide file tree

Showing 2 changed files with 15 additions and 7 deletions.
diff --git a/internal/sketch.go b/internal/sketch.go
@@ -154,16 +154,11 @@ func (s *CountMinSketch) EnsureCapacity(size uint) {
 }
 
 func spread(h uint64) uint64 {
-	h ^= h >> 17
-	h *= 0xed5ad4bb
-	h ^= h >> 11
-	h *= 0xac4c1b51
-	h ^= h >> 15
 	return h
 }
 
 func rehash(h uint64) uint64 {
-	h *= 0x31848bab
-	h ^= h >> 14
+	h *= 0x94d049bb133111eb
+	h ^= h >> 31
 	return h
 }
diff --git a/internal/sketch_test.go b/internal/sketch_test.go
@@ -71,6 +71,19 @@ func TestSketch_ResetFreq(t *testing.T) {
 
 }
 
+func TestSketch_Small(t *testing.T) {
+	sketch := NewCountMinSketch()
+	sketch.EnsureCapacity(512)
+	hasher := NewHasher[uint64](nil)
+	for i := 0; i < 605; i++ {
+		fmt.Printf("add %d:", i)
+		h := hasher.hash(uint64(i))
+		sketch.Add(h)
+		require.Equal(t, 1, int(sketch.Estimate(h)), i)
+
+	}
+}
+
 func TestSketch_ResetAddition(t *testing.T) {
 	sketch := NewCountMinSketch()
 	sketch.EnsureCapacity(100)