FIX: implementation of WrappedResponse

src/caosdb/connection/connection.py

@@ -65,6 +65,9 @@ class _WrappedHTTPResponse(CaosDBHTTPResponse):
 
     def __init__(self, response):
         self.response = response
+        self._generator = None
+        self._buffer = b''
+        self._stream_consumed = False
 
     @property
     def reason(self):
@@ -75,12 +78,44 @@ class _WrappedHTTPResponse(CaosDBHTTPResponse):
         return self.response.status_code
 
     def read(self, size=None):
-        if size is None or size == 0:
-            result = b''
-            for chunk in self.response.iter_content(chunk_size=1024):
-                result = result + chunk
+        if self._stream_consumed is True:
+            raise RuntimeError("Stream is consumed")
+
+        if self._buffer is None:
+            # the buffer has been drained in the previous call.
+            self._stream_consumed = True
+            return b''
+
+        if self._generator is None and (size is None or size == 0):
+            # return full content at once
+            self._stream_consumed = True
+            return self.response.content
+
+        if len(self._buffer) >= size:
+            # still enough bytes in the buffer
+            result = chunk[:size]
+            self._buffer = chunk[size:]
+            return result
+
+        if self._generator is None:
+            # first call to this method
+            if size is None or size == 0:
+                size = 512
+            self._generator = self.response.iter_content(size)
+
+        try:
+            # read new data into the buffer
+            chunk = self._buffer + next(self._generator)
+            result = chunk[:size]
+            if len(result) == 0:
+                self._stream_consumed = True
+            self._buffer = chunk[size:]
+            return result
+        except StopIteration:
+            # drain buffer
+            result = self._buffer
+            self._buffer = None
             return result
-        return self.response.iter_content(size)
 
     def getheader(self, name, default=None):
         return self.response.headers[name] if name in self.response.headers else default