Merge pull request #473 from subyraman/explore-streams-v2

Add `stream` method for streaming content, add docs and examples

sanic/server.py

@@ -159,20 +159,63 @@ class HttpProtocol(asyncio.Protocol):
     def on_message_complete(self):
         if self.request.body:
             self.request.body = b''.join(self.request.body)
+
         self._request_handler_task = self.loop.create_task(
-            self.request_handler(self.request, self.write_response))
+            self.request_handler(
+                self.request,
+                self.write_response,
+                self.stream_response))
 
     # -------------------------------------------- #
     # Responding
     # -------------------------------------------- #
-
     def write_response(self, response):
-        keep_alive = (
-            self.parser.should_keep_alive() and not self.signal.stopped)
+        """
+        Writes response content synchronously to the transport.
+        """
         try:
+            keep_alive = (
+                self.parser.should_keep_alive() and not self.signal.stopped)
+
             self.transport.write(
                 response.output(
-                    self.request.version, keep_alive, self.request_timeout))
+                    self.request.version, keep_alive,
+                    self.request_timeout))
+        except AttributeError:
+            log.error(
+                ('Invalid response object for url {}, '
+                 'Expected Type: HTTPResponse, Actual Type: {}').format(
+                    self.url, type(response)))
+            self.write_error(ServerError('Invalid response type'))
+        except RuntimeError:
+            log.error(
+                'Connection lost before response written @ {}'.format(
+                    self.request.ip))
+        except Exception as e:
+            self.bail_out(
+                "Writing response failed, connection closed {}".format(
+                    repr(e)))
+        finally:
+            if not keep_alive:
+                self.transport.close()
+            else:
+                self._last_request_time = current_time
+                self.cleanup()
+
+    async def stream_response(self, response):
+        """
+        Streams a response to the client asynchronously. Attaches
+        the transport to the response so the response consumer can
+        write to the response as needed.
+        """
+
+        try:
+            keep_alive = (
+                self.parser.should_keep_alive() and not self.signal.stopped)
+
+            response.transport = self.transport
+            await response.stream(
+                self.request.version, keep_alive, self.request_timeout)
         except AttributeError:
             log.error(
                 ('Invalid response object for url {}, '
@@ -191,7 +234,6 @@ class HttpProtocol(asyncio.Protocol):
             if not keep_alive:
                 self.transport.close()
             else:
-                # Record that we received data
                 self._last_request_time = current_time
                 self.cleanup()