Fix #2698: set write buffer limit to zero on client and server

CHANGES/2698.feature

@@ -0,0 +1 @@
+Set write buffer limit to zero for both client and server.

aiohttp/client_proto.py

@@ -58,6 +58,7 @@ def is_connected(self):
 
     def connection_made(self, transport):
         self.transport = transport
+        transport.set_write_buffer_limits(0)
 
     def connection_lost(self, exc):
         if self._payload_parser is not None:

aiohttp/web_protocol.py

@@ -174,6 +174,7 @@ def connection_made(self, transport):
         super().connection_made(transport)
 
         self.transport = transport
+        transport.set_write_buffer_limits(0)
 
         if self._tcp_keepalive:
             tcp_keepalive(transport)

tests/test_client_proto.py

@@ -96,3 +96,10 @@ async def test_empty_data(loop):
     proto.data_received(b'')
 
     # do nothing
+
+
+async def test_disable_write_buffer(loop):
+    proto = ResponseHandler(loop=loop)
+    transport = mock.Mock()
+    proto.connection_made(transport)
+    transport.set_write_buffer_limits.assert_called_with(0)

tests/test_web_protocol.py

@@ -817,3 +817,7 @@ def test_two_data_received_without_waking_up_start_task(srv, loop):
 
     assert len(srv._messages) == 2
     assert srv._waiter.done()
+
+
+def test_disable_write_buffer(srv):
+    srv.transport.set_write_buffer_limits.assert_called_with(0)