reduce allocations when binding string/time args

sqlite3.go

@@ -382,6 +382,7 @@ type SQLiteStmt struct {
 	t      string
 	closed bool
 	cls    bool // True if the statement was created by SQLiteConn.Query
+	reset  bool // True if the statement needs to reset before reuse
 }
 
 // SQLiteResult implements sql.Result.
@@ -1921,26 +1922,97 @@ func (s *SQLiteStmt) NumInput() int {
 
 var placeHolder = []byte{0}
 
+func hasNamedArgs(args []driver.NamedValue) bool {
+	for _, v := range args {
+		if v.Name != "" {
+			return true
+		}
+	}
+	return false
+}
+
 func (s *SQLiteStmt) bind(args []driver.NamedValue) error {
-	rv := C.sqlite3_reset(s.s)
-	if rv != C.SQLITE_ROW && rv != C.SQLITE_OK && rv != C.SQLITE_DONE {
-		return s.c.lastError()
+	if s.reset {
+		// The statement was previously used so we need to reset it.
+		rv := C.sqlite3_reset(s.s)
+		if rv != C.SQLITE_ROW && rv != C.SQLITE_OK && rv != C.SQLITE_DONE {
+			return s.c.lastError()
+		}
+	} else {
+		// First call to bind, future calls will need to reset the statement.
+		s.reset = true
+	}
+
+	if hasNamedArgs(args) {
+		return s.bindIndices(args)
+	}
+
+	var rv C.int
+	for _, arg := range args {
+		n := C.int(arg.Ordinal)
+		switch v := arg.Value.(type) {
+		case nil:
+			rv = C.sqlite3_bind_null(s.s, n)
+		case string:
+			p := stringData(v)
+			rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(p)), C.int(len(v)))
+		case int64:
+			rv = C.sqlite3_bind_int64(s.s, n, C.sqlite3_int64(v))
+		case bool:
+			val := 0
+			if v {
+				val = 1
+			}
+			rv = C.sqlite3_bind_int(s.s, n, C.int(val))
+		case float64:
+			rv = C.sqlite3_bind_double(s.s, n, C.double(v))
+		case []byte:
+			if v == nil {
+				rv = C.sqlite3_bind_null(s.s, n)
+			} else {
+				ln := len(v)
+				if ln == 0 {
+					v = placeHolder
+				}
+				rv = C._sqlite3_bind_blob(s.s, n, unsafe.Pointer(&v[0]), C.int(ln))
+			}
+		case time.Time:
+			ts := v.Format(SQLiteTimestampFormats[0])
+			p := stringData(ts)
+			rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(p)), C.int(len(ts)))
+		}
+		if rv != C.SQLITE_OK {
+			return s.c.lastError()
+		}
 	}
+	return nil
+}
+
+func (s *SQLiteStmt) bindIndices(args []driver.NamedValue) error {
+	// Find the longest named parameter name.
+	n := 0
+	for _, v := range args {
+		if m := len(v.Name); m > n {
+			n = m
+		}
+	}
+	buf := make([]byte, 0, n+2) // +2 for placeholder and null terminator
 
 	bindIndices := make([][3]int, len(args))
-	prefixes := []string{":", "@", "$"}
 	for i, v := range args {
 		bindIndices[i][0] = args[i].Ordinal
 		if v.Name != "" {
-			for j := range prefixes {
-				cname := C.CString(prefixes[j] + v.Name)
-				bindIndices[i][j] = int(C.sqlite3_bind_parameter_index(s.s, cname))
-				C.free(unsafe.Pointer(cname))
+			for j, c := range []byte{':', '@', '$'} {
+				buf = append(buf[:0], c)
+				buf = append(buf, v.Name...)
+				buf = append(buf, 0)
+				bindIndices[i][j] = int(C.sqlite3_bind_parameter_index(s.s, (*C.char)(unsafe.Pointer(&buf[0]))))
 			}
 			args[i].Ordinal = bindIndices[i][0]
 		}
 	}
 
+	var rv C.int
 	for i, arg := range args {
 		for j := range bindIndices[i] {
 			if bindIndices[i][j] == 0 {
@@ -1951,20 +2023,16 @@ func (s *SQLiteStmt) bind(args []driver.NamedValue) error {
 			case nil:
 				rv = C.sqlite3_bind_null(s.s, n)
 			case string:
-				if len(v) == 0 {
-					rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(&placeHolder[0])), C.int(0))
-				} else {
-					b := []byte(v)
-					rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(&b[0])), C.int(len(b)))
-				}
+				p := stringData(v)
+				rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(p)), C.int(len(v)))
 			case int64:
 				rv = C.sqlite3_bind_int64(s.s, n, C.sqlite3_int64(v))
 			case bool:
+				val := 0
 				if v {
-					rv = C.sqlite3_bind_int(s.s, n, 1)
-				} else {
-					rv = C.sqlite3_bind_int(s.s, n, 0)
+					val = 1
 				}
+				rv = C.sqlite3_bind_int(s.s, n, C.int(val))
 			case float64:
 				rv = C.sqlite3_bind_double(s.s, n, C.double(v))
 			case []byte:
@@ -1978,8 +2046,9 @@ func (s *SQLiteStmt) bind(args []driver.NamedValue) error {
 					rv = C._sqlite3_bind_blob(s.s, n, unsafe.Pointer(&v[0]), C.int(ln))
 				}
 			case time.Time:
-				b := []byte(v.Format(SQLiteTimestampFormats[0]))
-				rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(&b[0])), C.int(len(b)))
+				ts := v.Format(SQLiteTimestampFormats[0])
+				p := stringData(ts)
+				rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(p)), C.int(len(ts)))
 			}
 			if rv != C.SQLITE_OK {
 				return s.c.lastError()

unsafe_go120.go

@@ -0,0 +1,17 @@
+//go:build !go1.21
+// +build !go1.21
+
+package sqlite3
+
+import "unsafe"
+
+// stringData is a safe version of unsafe.StringData that handles empty strings.
+func stringData(s string) *byte {
+	if len(s) != 0 {
+		b := *(*[]byte)(unsafe.Pointer(&s))
+		return &b[0]
+	}
+	// The return value of unsafe.StringData
+	// is unspecified if the string is empty.
+	return &placeHolder[0]
+}

unsafe_go121.go

@@ -0,0 +1,23 @@
+//go:build go1.21
+// +build go1.21
+
+// The unsafe.StringData function was made available in Go 1.20 but it
+// was not until Go 1.21 that Go was changed to interpret the Go version
+// in go.mod (1.19 as of writing this) as the minimum version required
+// instead of the exact version.
+//
+// See: https://github.com/golang/go/issues/59033
+
+package sqlite3
+
+import "unsafe"
+
+// stringData is a safe version of unsafe.StringData that handles empty strings.
+func stringData(s string) *byte {
+	if len(s) != 0 {
+		return unsafe.StringData(s)
+	}
+	// The return value of unsafe.StringData
+	// is unspecified if the string is empty.
+	return &placeHolder[0]
+}