Fix memory leak in SplitArray.Remove

spacepartition/leak_test.go

@@ -0,0 +1,59 @@
+package spacepartition
+
+import (
+	"testing"
+	"github.com/arran4/spacemap/shared"
+)
+
+func TestSplitArrayRemoveLeak(t *testing.T) {
+	// Create a SplitArray with a few elements
+	s1 := &Split{Position: 10, Alignment: Vertical, BecauseOf: []shared.Shape{shared.NewRectangle(0,0,1,1)}}
+
+	shapeToRemove := shared.NewRectangle(0, 0, 100, 100)
+	s2 := &Split{Position: 20, Alignment: Vertical, BecauseOf: []shared.Shape{shapeToRemove}}
+
+	s3 := &Split{Position: 30, Alignment: Vertical, BecauseOf: []shared.Shape{shared.NewRectangle(0,0,1,1)}}
+
+	sa := SplitArray{s1, s2, s3}
+
+	// Perform remove
+	newSa, _ := sa.Remove(shapeToRemove)
+
+	// Check new length
+	if len(newSa) != 2 {
+		t.Fatalf("Expected length 2, got %d", len(newSa))
+	}
+
+	// Check for leak
+	// The backing array has capacity 3.
+	// After removing s2 (middle), the array becomes [s1, s3, s3].
+	// The element at index 2 (last one) should be nil if we want to fix the leak.
+
+	leakedSlice := newSa[:cap(newSa)]
+	if leakedSlice[2] != nil {
+		t.Logf("Memory leak detected: element at index 2 is %v", leakedSlice[2])
+		// We fail if we want to assert the leak is present (for baseline) or absent (for verification).
+		// Since this is a "reproduction test", failing means we successfully reproduced the issue.
+		// However, for the final state, we want this to PASS.
+		// So I will write this test to FAIL if the leak is present.
+		t.Fail()
+	}
+}
+
+func BenchmarkSplitArrayRemove(b *testing.B) {
+	s1 := &Split{Position: 10, Alignment: Vertical, BecauseOf: []shared.Shape{shared.NewRectangle(0,0,1,1)}}
+	shapeToRemove := shared.NewRectangle(0, 0, 100, 100)
+	s2 := &Split{Position: 20, Alignment: Vertical, BecauseOf: []shared.Shape{shapeToRemove}}
+	s3 := &Split{Position: 30, Alignment: Vertical, BecauseOf: []shared.Shape{shared.NewRectangle(0,0,1,1)}}
+
+	baseSa := SplitArray{s1, s2, s3}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		// Copy baseSa so we don't mutate the original in the loop
+		sa := make(SplitArray, len(baseSa))
+		copy(sa, baseSa)
+
+		sa.Remove(shapeToRemove)
+	}
+}

spacepartition/spacemap.go

@@ -295,6 +295,9 @@ func (sa SplitArray) Remove(shape shared.Shape) ([]*Split, []*Split) {
 			shrink++
 		}
 	}
+	for i := 0; i < shrink; i++ {
+		sa[len(sa)-1-i] = nil
+	}
 	return sa[:len(sa)-shrink], removedFrom
 }