Fix allocations in bytes_len_cmp (#672)

pipeline/doif/do_if_test.go

@@ -1079,7 +1079,10 @@ const userInfoRawJSON = `
 {
 	"name": "jack",
 	"age": 120,
-	"hobbies": ["football", "diving"]
+	"hobbies": ["football", "diving"],
+	"obj": {
+		"a": "b"
+	}
 }`
 
 func dryJSON(rawJSON string) string {

pipeline/doif/len_cmp_op.go

@@ -129,6 +129,51 @@ func (n *lenCmpOpNode) Type() NodeType {
 	return NodeLengthCmpOp
 }
 
+func getNodeFieldsBytesSize(node *insaneJSON.Node) int {
+	size := 0
+	fields := node.AsFields()
+	for _, elemNode := range fields {
+		// field node is a field name and it is always a string enclosed with double quotes
+		// Note: there is one corner case for field names with escaping `\"`.
+		// In that case output bytes count will be less than actual because insaneJSON always escapes field names when using `AsFields`.
+		size += len(elemNode.AsString()) + 2 + 1 // quotes enclosing field name and colon between key and value
+
+		elemNodeVal := elemNode.AsFieldValue()
+		size += getNodeBytesSize(elemNodeVal)
+	}
+	size += len(fields) - 1 // commas between object fields
+	return size
+}
+
+func getNodeBytesSize(node *insaneJSON.Node) int {
+	if node == nil {
+		return 0
+	}
+	size := 0
+	switch {
+	case node.IsArray():
+		nodeArr := node.AsArray()
+		for _, elemNode := range nodeArr {
+			size += getNodeBytesSize(elemNode)
+		}
+		size += len(nodeArr) - 1 + 2 // commas between elements and square brackets enclosing array
+	case node.IsObject():
+		size += getNodeFieldsBytesSize(node) + 2 // curly brackets enclosing object
+	default:
+		if node.IsString() {
+			if node.TypeStr() == "hellBitString" {
+				// Note: in case of unescaped string computed bytes length can diverse from the actual
+				size += len(node.AsString()) + 2 // add quotes to unescaped string
+			} else {
+				size += len(node.AsEscapedString())
+			}
+		} else {
+			size += len(node.AsString())
+		}
+	}
+	return size
+}
+
 func (n *lenCmpOpNode) Check(eventRoot *insaneJSON.Root) bool {
 	value := 0
 
@@ -140,7 +185,7 @@ func (n *lenCmpOpNode) Check(eventRoot *insaneJSON.Root) bool {
 		}
 
 		if node.IsObject() || node.IsArray() {
-			value = len(node.EncodeToByte())
+			value = getNodeBytesSize(node)
 		} else {
 			value = len(node.AsString())
 		}