optimized memory allocation

golang · pavlov061356 · Sep 26, 2024 · Sep 30, 2024 · Oct 1, 2024 · Oct 1, 2024
commit ea1220a9d098c7c3d45b860f1f5c98541e7c0f0a
diff --git a/s2/chain_interpolation_query.go b/s2/chain_interpolation_query.go
@@ -202,7 +202,7 @@ func (s ChainInterpolationQuery) Slice(beginFraction, endFraction float64) []Poi
 // If the query is either uninitialized, or initialized with a shape
 // containing no edges, then an empty vector is returned.
 func (s ChainInterpolationQuery) SliceDivided(beginFraction, endFraction float64, divisions int) []Point {
-	var points []Point
+	points := make([]Point, 0, divisions)
 	s.AddDividedSlice(beginFraction, endFraction, &points, divisions)
 	return points
 }

diff --git a/s2/chain_interpolation_query_test.go b/s2/chain_interpolation_query_test.go
@@ -831,7 +831,7 @@ func TestSliceDivided(t *testing.T) {
 // cpu: AMD Ryzen 5 5600G with Radeon Graphics
 // === RUN   Benchmark_SliceDivided
 // Benchmark_SliceDivided
-// Benchmark_SliceDivided-12           8101            128452 ns/op           49104 B/op         20 allocs/op
+// Benchmark_SliceDivided-12           8101            128452 ns/op           24577 B/op         2 allocs/op
 
 func Benchmark_SliceDivided(b *testing.B) {
 	chainInterpolationQuery := InitChainInterpolationQuery(
@@ -928,3 +928,15 @@ func TestChainInterpolationQuery_EdgesBetween(t *testing.T) {
 		})
 	}
 }
+
+func Benchmark_InitChinInterpolationQuery(b *testing.B) {
+	points := make([]Point, 0, b.N)
+	for i := 0; i < b.N; i++ {
+		points = append(points, PointFromLatLng(LatLngFromDegrees(0, float64(i))))
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		InitChainInterpolationQuery(laxPolylineFromPoints(points), 0)
+	}
+}