From af8a4da6d9cbeb372999e8ff4710bb1944bdb561 Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Tue, 30 Nov 2021 22:30:44 +0300
Subject: [PATCH] stackitem: use type switch more effectively
MIME-Version: 1.0
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Reduce the number of allocations, save some time.

name               old time/op    new time/op    delta
EncodeBinary-8       51.2µs ± 8%    44.6µs ± 7%  -12.79%  (p=0.008 n=5+5)
SerializeSimple-8     523ns ± 5%     449ns ± 4%  -14.27%  (p=0.008 n=5+5)

name               old alloc/op   new alloc/op   delta
EncodeBinary-8        329kB ± 0%     329kB ± 0%   -0.12%  (p=0.008 n=5+5)
SerializeSimple-8      432B ± 0%      408B ± 0%   -5.56%  (p=0.008 n=5+5)

name               old allocs/op  new allocs/op  delta
EncodeBinary-8         36.0 ± 0%      20.0 ± 0%  -44.44%  (p=0.008 n=5+5)
SerializeSimple-8      7.00 ± 0%      6.00 ± 0%  -14.29%  (p=0.008 n=5+5)
---
 pkg/vm/stackitem/serialization.go | 36 +++++++++++++++++--------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/pkg/vm/stackitem/serialization.go b/pkg/vm/stackitem/serialization.go
index 9ee70889b..e11da49c1 100644
--- a/pkg/vm/stackitem/serialization.go
+++ b/pkg/vm/stackitem/serialization.go
@@ -85,6 +85,18 @@ func EncodeBinaryProtected(item Item, w *io.BinWriter) {
 	w.WriteBytes(sc.data)
 }
 
+func (w *serContext) writeArray(item Item, arr []Item, start int) error {
+	w.seen[item] = sliceNoPointer{}
+	w.appendVarUint(uint64(len(arr)))
+	for i := range arr {
+		if err := w.serialize(arr[i]); err != nil {
+			return err
+		}
+	}
+	w.seen[item] = sliceNoPointer{start, len(w.data)}
+	return nil
+}
+
 func (w *serContext) serialize(item Item) error {
 	if v, ok := w.seen[item]; ok {
 		if v.start == v.end {
@@ -127,24 +139,16 @@ func (w *serContext) serialize(item Item) error {
 		} else {
 			return fmt.Errorf("%w: Interop", ErrUnserializable)
 		}
-	case *Array, *Struct:
-		w.seen[item] = sliceNoPointer{}
-
-		_, isArray := t.(*Array)
-		if isArray {
-			w.data = append(w.data, byte(ArrayT))
-		} else {
-			w.data = append(w.data, byte(StructT))
+	case *Array:
+		w.data = append(w.data, byte(ArrayT))
+		if err := w.writeArray(item, t.value, start); err != nil {
+			return err
 		}
-
-		arr := t.Value().([]Item)
-		w.appendVarUint(uint64(len(arr)))
-		for i := range arr {
-			if err := w.serialize(arr[i]); err != nil {
-				return err
-			}
+	case *Struct:
+		w.data = append(w.data, byte(StructT))
+		if err := w.writeArray(item, t.value, start); err != nil {
+			return err
 		}
-		w.seen[item] = sliceNoPointer{start, len(w.data)}
 	case *Map:
 		w.seen[item] = sliceNoPointer{}