wsgi: Fix handling partial writeswritelines-fix

Closes https://github.com/eventlet/eventlet/issues/295

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/wsgi_test.py b/tests/wsgi_test.py
index 50091eb..2c25553 100644
--- a/tests/wsgi_test.py
+++ b/tests/wsgi_test.py
@@ -10,6 +10,8 @@ import tempfile
 import traceback
 import unittest
 
+from nose.tools import eq_
+
 import eventlet
 from eventlet import debug
 from eventlet import event
@@ -444,6 +446,43 @@ class TestHttpd(_TestBase):
         # Require a CRLF to close the message body
         self.assertEqual(response, b'\r\n')
 
+    def test_partial_writes_are_handled(self):
+        # The bug was caused by the default writelines() implementaiton
+        # (used by the wsgi module) which doesn't check if write()
+        # successfully completed sending *all* data therefore data could be
+        # lost and the client could be left hanging forever.
+        #
+        # Eventlet issue: "Python 3: wsgi doesn't handle correctly partial
+        # write of socket send() when using writelines()",
+        # https://github.com/eventlet/eventlet/issues/295
+        #
+        # Related CPython issue: "Raw I/O writelines() broken",
+        # http://bugs.python.org/issue26292
+
+        # Piece of data large enough that we can reasonably expect it to not
+        # be sent in one piece. Is there a reliable way to determine this
+        # number without testing various sizes empirically?
+        data = b'a' * 10 ** 7
+
+        def application(env, start_response):
+            # Sending content-length is important here, otherwise chunked encoding
+            # is chosen
+            start_response('200 OK', [])
+            yield data
+
+        self.site.application = application
+
+        sock = eventlet.connect(('localhost', self.port))
+
+        # HTTP 1.0 is important here, this tells the server to close the socket
+        # after sending the data so that read_http() can safely read until EOF
+        # without hanging forever.
+        sock.sendall(b'GET / HTTP/1.0\r\nHost: localhost\r\n\r\n')
+        result = read_http(sock)
+
+        # This would previously fail because part of the data would be lost
+        eq_(len(result.body), len(data))
+
     @tests.skip_if_no_ssl
     def test_012_ssl_server(self):
         def wsgi_app(environ, start_response):