response.write should be synchronous for performance reasons

docs/sanic/streaming.md

@@ -11,8 +11,8 @@ app = Sanic(__name__)
 @app.route("/")
 async def test(request):
     async def sample_streaming_fn(response):
-        await response.write('foo,')
-        await response.write('bar')
+        response.write('foo,')
+        response.write('bar')
 
     return stream(sample_streaming_fn, content_type='text/csv')
 ```
@@ -26,7 +26,7 @@ async def index(request):
         conn = await asyncpg.connect(database='test')
         async with conn.transaction():
             async for record in conn.cursor('SELECT generate_series(0, 10)'):
-                await response.write(record[0])
+                response.write(record[0])
 
     return stream(stream_from_db)
 ```

sanic/response.py

@@ -109,19 +109,21 @@ class StreamingHTTPResponse(BaseHTTPResponse):
         'status', 'content_type', 'headers', '_cookies')
 
     def __init__(self, streaming_fn, status=200, headers=None,
-                 content_type='text/plain', body_bytes=b''):
+                 content_type='text/plain'):
         self.content_type = content_type
         self.streaming_fn = streaming_fn
         self.status = status
         self.headers = headers or {}
         self._cookies = None
 
-    async def write(self, data):
+    def write(self, data):
         """Writes a chunk of data to the streaming response.
 
         :param data: bytes-ish data to be written.
         """
-        data = self._encode_body(data)
+        if type(data) != bytes:
+            data = self._encode_body(data)
+
         self.transport.write(
             b"%b\r\n%b\r\n" % (str(len(data)).encode(), data))
 

tests/test_response.py

@@ -22,9 +22,9 @@ def test_response_body_not_a_string():
 
 
 async def sample_streaming_fn(response):
-    await response.write('foo,')
+    response.write('foo,')
     await asyncio.sleep(.001)
-    await response.write('bar')
+    response.write('bar')
 
 
 @pytest.fixture