[Python-checkins] cpython (3.4): Issue #25441: asyncio: Raise error from drain() when socket is closed.

Mon Oct 19 15:01:15 EDT 2015

https://hg.python.org/cpython/rev/17f76258d11d
changeset: 98791:17f76258d11d
branch: 3.4
parent: 98788:74b6b19e52b4
user: Guido van Rossum <guido at python.org>
date: Mon Oct 19 11:49:30 2015 -0700
summary:
 Issue #25441: asyncio: Raise error from drain() when socket is closed.
files:
 Lib/asyncio/streams.py | 9 +++
 Lib/test/test_asyncio/test_streams.py | 43 +++++++++++++++
 Misc/NEWS | 2 +
 3 files changed, 54 insertions(+), 0 deletions(-)

diff --git a/Lib/asyncio/streams.py b/Lib/asyncio/streams.py
--- a/Lib/asyncio/streams.py
+++ b/Lib/asyncio/streams.py
@@ -301,6 +301,15 @@
 exc = self._reader.exception()
 if exc is not None:
 raise exc
+ if self._transport is not None:
+ if self._transport._closing:
+ # Yield to the event loop so connection_lost() may be
+ # called. Without this, _drain_helper() would return
+ # immediately, and code that calls
+ # write(...); yield from drain()
+ # in a loop would never call connection_lost(), so it
+ # would not see an error when the socket is closed.
+ yield
 yield from self._protocol._drain_helper()
 
 
diff --git a/Lib/test/test_asyncio/test_streams.py b/Lib/test/test_asyncio/test_streams.py
--- a/Lib/test/test_asyncio/test_streams.py
+++ b/Lib/test/test_asyncio/test_streams.py
@@ -2,8 +2,10 @@
 
 import gc
 import os
+import queue
 import socket
 import sys
+import threading
 import unittest
 from unittest import mock
 try:
@@ -632,6 +634,47 @@
 protocol = asyncio.StreamReaderProtocol(reader)
 self.assertIs(protocol._loop, self.loop)
 
+ def test_drain_raises(self):
+ # See http://bugs.python.org/issue25441
+
+ # This test should not use asyncio for the mock server; the
+ # whole point of the test is to test for a bug in drain()
+ # where it never gives up the event loop but the socket is
+ # closed on the server side.
+
+ q = queue.Queue()
+
+ def server():
+ # Runs in a separate thread.
+ sock = socket.socket()
+ sock.bind(('localhost', 0))
+ sock.listen(1)
+ addr = sock.getsockname()
+ q.put(addr)
+ clt, _ = sock.accept()
+ clt.close()
+ 
+ @asyncio.coroutine
+ def client(host, port):
+ reader, writer = yield from asyncio.open_connection(host, port, loop=self.loop)
+ while True:
+ writer.write(b"foo\n")
+ yield from writer.drain()
+
+ # Start the server thread and wait for it to be listening.
+ thread = threading.Thread(target=server)
+ thread.setDaemon(True)
+ thread.start()
+ addr = q.get()
+
+ # Should not be stuck in an infinite loop.
+ with self.assertRaises((ConnectionResetError, BrokenPipeError)):
+ self.loop.run_until_complete(client(*addr))
+
+ # Clean up the thread. (Only on success; on failure, it may
+ # be stuck in accept().)
+ thread.join()
+
 def test___repr__(self):
 stream = asyncio.StreamReader(loop=self.loop)
 self.assertEqual("<StreamReader>", repr(stream))
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -96,6 +96,8 @@
 Library
 -------
 
+- Issue #25441: asyncio: Raise error from drain() when socket is closed.
+
 - Issue #25411: Improved Unicode support in SMTPHandler through better use of
 the email package. Thanks to user simon04 for the patch.
 
-- 
Repository URL: https://hg.python.org/cpython
