From 1cc0ee7d9f6a2817918fafd24c18d8bb093a85d3 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Tue, 7 May 2019 16:53:19 -0400
Subject: bpo-36801: Fix waiting in StreamWriter.drain for closing SSL
 transport (GH-13098)

https://bugs.python.org/issue36801
---
 Lib/asyncio/streams.py | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

(limited to 'Lib/asyncio/streams.py')

diff --git a/Lib/asyncio/streams.py b/Lib/asyncio/streams.py
index c9b1f32813d..79adf028212 100644
--- a/Lib/asyncio/streams.py
+++ b/Lib/asyncio/streams.py
@@ -199,6 +199,9 @@ class FlowControlMixin(protocols.Protocol):
         self._drain_waiter = waiter
         await waiter
 
+    def _get_close_waiter(self, stream):
+        raise NotImplementedError
+
 
 class StreamReaderProtocol(FlowControlMixin, protocols.Protocol):
     """Helper class to adapt between Protocol and StreamReader.
@@ -315,6 +318,9 @@ class StreamReaderProtocol(FlowControlMixin, protocols.Protocol):
             return False
         return True
 
+    def _get_close_waiter(self, stream):
+        return self._closed
+
     def __del__(self):
         # Prevent reports about unhandled exceptions.
         # Better than self._closed._log_traceback = False hack
@@ -376,7 +382,7 @@ class StreamWriter:
         return self._transport.is_closing()
 
     async def wait_closed(self):
-        await self._protocol._closed
+        await self._protocol._get_close_waiter(self)
 
     def get_extra_info(self, name, default=None):
         return self._transport.get_extra_info(name, default)
@@ -394,13 +400,12 @@ class StreamWriter:
             if exc is not None:
                 raise exc
         if self._transport.is_closing():
-            # Yield to the event loop so connection_lost() may be
-            # called.  Without this, _drain_helper() would return
-            # immediately, and code that calls
-            #     write(...); await drain()
-            # in a loop would never call connection_lost(), so it
-            # would not see an error when the socket is closed.
-            await sleep(0, loop=self._loop)
+            # Wait for protocol.connection_lost() call
+            # Raise connection closing error if any,
+            # ConnectionResetError otherwise
+            fut = self._protocol._get_close_waiter(self)
+            await fut
+            raise ConnectionResetError('Connection lost')
         await self._protocol._drain_helper()
 
     async def aclose(self):
-- 
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