From be31d4686549d6acaf82e1e8415c2b9a9e4c741f Mon Sep 17 00:00:00 2001
From: Nathaniel Manista <nathaniel@google.com>
Date: Wed, 20 Jan 2016 00:01:34 +0000
Subject: [PATCH] A test of the Cython Channel

This exposes a bug somewhere in how channel connectivity events get
published on completion queues. Investigation remains active.
---
 .../tests/unit/_cython/_channel_test.py       | 83 +++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 src/python/grpcio/tests/unit/_cython/_channel_test.py

diff --git a/src/python/grpcio/tests/unit/_cython/_channel_test.py b/src/python/grpcio/tests/unit/_cython/_channel_test.py
new file mode 100644
index 00000000000..b414f8e6f69
--- /dev/null
+++ b/src/python/grpcio/tests/unit/_cython/_channel_test.py
@@ -0,0 +1,83 @@
+# Copyright 2016, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import time
+import threading
+import unittest
+
+from grpc._cython import cygrpc
+
+# TODO(nathaniel): This should be at least one hundred. Why not one thousand?
+_PARALLELISM = 4
+
+
+def _channel_and_completion_queue():
+  channel = cygrpc.Channel('localhost:54321', cygrpc.ChannelArgs(()))
+  completion_queue = cygrpc.CompletionQueue()
+  return channel, completion_queue
+
+
+def _connectivity_loop(channel, completion_queue):
+  for _ in range(100):
+    connectivity = channel.check_connectivity_state(True)
+    channel.watch_connectivity_state(
+        connectivity, cygrpc.Timespec(time.time() + 0.2), completion_queue,
+        None)
+    completion_queue.poll(deadline=cygrpc.Timespec(float('+inf')))
+
+
+def _create_loop_destroy():
+  channel, completion_queue = _channel_and_completion_queue()
+  _connectivity_loop(channel, completion_queue)
+  completion_queue.shutdown()
+
+
+def _in_parallel(behavior, arguments):
+  threads = tuple(
+      threading.Thread(target=behavior, args=arguments)
+      for _ in range(_PARALLELISM))
+  for thread in threads:
+    thread.start()
+  for thread in threads:
+    thread.join()
+
+
+class ChannelTest(unittest.TestCase):
+
+  def test_single_channel_lonely_connectivity(self):
+    channel, completion_queue = _channel_and_completion_queue()
+    _in_parallel(_connectivity_loop, (channel, completion_queue,))
+    completion_queue.shutdown()
+
+  def test_multiple_channels_lonely_connectivity(self):
+    _in_parallel(_create_loop_destroy, ())
+
+
+if __name__ == '__main__':
+  unittest.main(verbosity=2)