Use BytesIO as read buffer

Gr1N · Gr1N · commit 2af36f84304c · 2018-09-24T15:26:20.000+03:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## 0.4.0 (2018-XX-XX)
 
+- Use `BytesIO` as read buffer
+
 ## 0.3.0 (2018-09-25)
 
 - Improved receive messages logic
diff --git a/pynats/client.py b/pynats/client.py
@@ -266,19 +266,19 @@ def _recv(self, *commands: Pattern[bytes]) -> Tuple[Pattern[bytes], Match[bytes]
         return command, result
 
     def _readline(self, *, size: int = None) -> bytes:
-        read = b""
+        read = io.BytesIO()
 
         while True:
             line = cast(bytes, self._socket_file.readline())
-            read += line
+            read.write(line)
 
             if size is not None:
-                if len(self._strip(read)) == size:
+                if read.tell() == size + len(_CRLF_):
                     break
             elif line.endswith(_CRLF_):
                 break
 
-        return read
+        return read.getvalue()
 
     def _strip(self, line: bytes) -> bytes:
         return line[: -len(_CRLF_)]
