⚡ Fix memory leak in PointArray.Remove

shared/point.go

@@ -33,6 +33,10 @@ func (pa PointArray) Remove(shape Shape) ([]*Point, int) {
 			pa[i] = pa[len(pa)-shrink]
 		}
 	}
+	// Avoid memory leak by niling out the pointers in the removed section of the underlying array
+	for i := len(pa) - shrink; i < len(pa); i++ {
+		pa[i] = nil
+	}
 	return pa[:len(pa)-shrink], shrink
 }
 

shared/point_test.go

@@ -0,0 +1,64 @@
+package shared
+
+import (
+	"testing"
+)
+
+func TestPointArray_Remove_MemoryLeak(t *testing.T) {
+	// Create some shapes
+	s1 := NewRectangle(0, 0, 10, 10, Name("s1"))
+	s2 := NewRectangle(10, 10, 20, 20, Name("s2"))
+	s3 := NewRectangle(20, 20, 30, 30, Name("s3"))
+
+	p1 := &Point{ZIndex: 1, Shape: s1}
+	p2 := &Point{ZIndex: 2, Shape: s2}
+	p3 := &Point{ZIndex: 3, Shape: s3}
+
+	// Initialize PointArray with enough capacity
+	pa := make(PointArray, 0, 10)
+	pa = append(pa, p1, p2, p3)
+
+	// Remove p2
+	res, shrink := pa.Remove(s2)
+
+	if shrink != 1 {
+		t.Errorf("Expected shrink to be 1, got %d", shrink)
+	}
+
+	if len(res) != 2 {
+		t.Errorf("Expected result length to be 2, got %d", len(res))
+	}
+
+	// Check underlying array
+	// We need to re-slice to capacity to see the "removed" elements
+	underlying := res[:cap(res)]
+
+	leakIndex := len(res)
+	// The element at leakIndex corresponds to what was at the end of the slice before removal/swap
+	// In the swap algorithm: pa[i] = pa[len-shrink].
+	// The element at len-shrink remains there unless cleared.
+
+	if underlying[leakIndex] != nil {
+		t.Logf("Memory leak detected! Item at index %d in underlying array is not nil: %v", leakIndex, underlying[leakIndex])
+        t.Fail()
+	}
+}
+
+func BenchmarkPointArray_Remove(b *testing.B) {
+	s := NewRectangle(0, 0, 10, 10)
+	p := &Point{ZIndex: 1, Shape: s}
+
+    // Create a large array to make the effect measurable if we were testing speed,
+    // but here we are testing overhead of clearing.
+    // However, allocating in the loop might dominate.
+
+	for i := 0; i < b.N; i++ {
+		b.StopTimer()
+		pa := make(PointArray, 100)
+		for j := 0; j < 100; j++ {
+			pa[j] = p
+		}
+		b.StartTimer()
+		pa.Remove(s)
+	}
+}