Add StreamLineReader with unit tests

src/galaxy/reader.py

@@ -0,0 +1,28 @@
+from asyncio import StreamReader
+
+
+class StreamLineReader:
+    """Handles StreamReader readline without buffer limit"""
+    def __init__(self, reader: StreamReader):
+        self._reader = reader
+        self._buffer = bytes()
+        self._processed_buffer_it = 0
+
+    async def readline(self):
+        while True:
+            # check if there is no unprocessed data in the buffer
+            if not self._buffer or self._processed_buffer_it != 0:
+                chunk = await self._reader.read(1024)
+                if not chunk:
+                    return bytes() # EOF
+                self._buffer += chunk
+
+            it = self._buffer.find(b"\n", self._processed_buffer_it)
+            if it < 0:
+                self._processed_buffer_it = len(self._buffer)
+                continue
+
+            line = self._buffer[:it]
+            self._buffer = self._buffer[it+1:]
+            self._processed_buffer_it = 0
+            return line