comments

Author: max-hoffman

server/handler.go

@@ -936,7 +936,7 @@ func toSqlHelper(ctx *sql.Context, typ sql.Type, buf *sql.ByteBuffer, val interf
 		return typ.SQL(ctx, nil, val)
 	}
 	ret, err := typ.SQL(ctx, buf.Get(), val)
-	buf.Update(ret.Raw())
+	buf.Grow(ret.Len())
 	return ret, err
 }
 

sql/byte_buffer.go

@@ -22,24 +22,32 @@ func NewByteBuffer(initCap int) *ByteBuffer {
 	return &ByteBuffer{buf: buf}
 }
 
-func (b *ByteBuffer) Update(buf []byte) {
-	if b.i+len(buf) > len(b.buf) {
+// Grow records the latest used byte position. Callers
+// are responsible for accurately reporting which bytes
+// they expect to be protected.
+func (b *ByteBuffer) Grow(n int) {
+	if b.i+n > len(b.buf) {
 		// Runtime alloc'd into a separate backing array, but it chooses
 		// the doubling cap using the non-optimal |cap(b.buf)-b.i|*2.
 		// We do not need to increment |b.i| b/c the latest value is in
 		// the other array.
 		b.Double()
 	} else {
-		b.i += len(buf)
+		b.i += n
 	}
 }
 
+// Double expands the backing array by 2x. We do this
+// here because the runtime only doubles based on slice
+// length.
 func (b *ByteBuffer) Double() {
 	buf := make([]byte, len(b.buf)*2)
 	copy(buf, b.buf)
 	b.buf = buf
 }
 
+// Get returns a zero length slice beginning at a safe
+// write position.
 func (b *ByteBuffer) Get() []byte {
 	return b.buf[b.i:b.i]
 }

sql/types/sql_test.go

@@ -28,7 +28,7 @@ func BenchmarkVarchar10SQL(b *testing.B) {
 	ctx := sql.NewEmptyContext()
 	for i := 0; i < b.N; i++ {
 		res, _ = t.SQL(ctx, buf.Get(), "char")
-		buf.Update(res.Raw())
+		buf.Grow(res.Len())
 		buf.Reset()
 	}
 	result_ = res