Adapt _intermediary_low_test to no backup poller

Pull request #1577 removes the backup poller internal to completion
queues so this test needs to use extra threads to drive the work done
inside the completion queues by continuously calling each completion
queue's get method.

src/python/src/grpc/_adapter/_intermediary_low_test.py

@@ -29,6 +29,8 @@
 
 """Tests for the old '_low'."""
 
+import Queue
+import threading
 import time
 import unittest
 
@@ -43,6 +45,7 @@ _BYTE_SEQUENCE_SEQUENCE = tuple(
     bytes(bytearray((row + column) % 256 for column in range(row)))
     for row in range(_STREAM_LENGTH))
 
+
 class LonelyClientTest(unittest.TestCase):
 
   def testLonelyClient(self):
@@ -79,6 +82,14 @@ class LonelyClientTest(unittest.TestCase):
     del completion_queue
 
 
+def _drive_completion_queue(completion_queue, event_queue):
+  while True:
+    event = completion_queue.get(_FUTURE)
+    if event.kind is _low.Event.Kind.STOP:
+      break
+    event_queue.put(event)
+
+
 class EchoTest(unittest.TestCase):
 
   def setUp(self):
@@ -88,24 +99,26 @@ class EchoTest(unittest.TestCase):
     self.server = _low.Server(self.server_completion_queue)
     port = self.server.add_http2_addr('[::]:0')
     self.server.start()
+    self.server_events = Queue.Queue()
+    self.server_completion_queue_thread = threading.Thread(
+        target=_drive_completion_queue,
+        args=(self.server_completion_queue, self.server_events))
+    self.server_completion_queue_thread.start()
 
     self.client_completion_queue = _low.CompletionQueue()
     self.channel = _low.Channel('%s:%d' % (self.host, port), None)
+    self.client_events = Queue.Queue()
+    self.client_completion_queue_thread = threading.Thread(
+        target=_drive_completion_queue,
+        args=(self.client_completion_queue, self.client_events))
+    self.client_completion_queue_thread.start()
 
   def tearDown(self):
     self.server.stop()
     self.server_completion_queue.stop()
     self.client_completion_queue.stop()
-    while True:
+    self.server_completion_queue_thread.join()
-      event = self.server_completion_queue.get(_FUTURE)
+    self.client_completion_queue_thread.join()
-      if event is not None and event.kind is _low.Event.Kind.STOP:
-        break
-    while True:
-      event = self.client_completion_queue.get(_FUTURE)
-      if event is not None and event.kind is _low.Event.Kind.STOP:
-        break
-    self.server_completion_queue = None
-    self.client_completion_queue = None
     del self.server
 
   def _perform_echo_test(self, test_data):
@@ -144,7 +157,7 @@ class EchoTest(unittest.TestCase):
     client_call.invoke(self.client_completion_queue, metadata_tag, finish_tag)
 
     self.server.service(service_tag)
-    service_accepted = self.server_completion_queue.get(_FUTURE)
+    service_accepted = self.server_events.get()
     self.assertIsNotNone(service_accepted)
     self.assertIs(service_accepted.kind, _low.Event.Kind.SERVICE_ACCEPTED)
     self.assertIs(service_accepted.tag, service_tag)
@@ -165,7 +178,7 @@ class EchoTest(unittest.TestCase):
                              server_leading_binary_metadata_value)
     server_call.premetadata()
 
-    metadata_accepted = self.client_completion_queue.get(_FUTURE)
+    metadata_accepted = self.client_events.get()
     self.assertIsNotNone(metadata_accepted)
     self.assertEqual(_low.Event.Kind.METADATA_ACCEPTED, metadata_accepted.kind)
     self.assertEqual(metadata_tag, metadata_accepted.tag)
@@ -179,14 +192,14 @@ class EchoTest(unittest.TestCase):
 
     for datum in test_data:
       client_call.write(datum, write_tag)
-      write_accepted = self.client_completion_queue.get(_FUTURE)
+      write_accepted = self.client_events.get()
       self.assertIsNotNone(write_accepted)
       self.assertIs(write_accepted.kind, _low.Event.Kind.WRITE_ACCEPTED)
       self.assertIs(write_accepted.tag, write_tag)
       self.assertIs(write_accepted.write_accepted, True)
 
       server_call.read(read_tag)
-      read_accepted = self.server_completion_queue.get(_FUTURE)
+      read_accepted = self.server_events.get()
       self.assertIsNotNone(read_accepted)
       self.assertEqual(_low.Event.Kind.READ_ACCEPTED, read_accepted.kind)
       self.assertEqual(read_tag, read_accepted.tag)
@@ -194,14 +207,14 @@ class EchoTest(unittest.TestCase):
       server_data.append(read_accepted.bytes)
 
       server_call.write(read_accepted.bytes, write_tag)
-      write_accepted = self.server_completion_queue.get(_FUTURE)
+      write_accepted = self.server_events.get()
       self.assertIsNotNone(write_accepted)
       self.assertEqual(_low.Event.Kind.WRITE_ACCEPTED, write_accepted.kind)
       self.assertEqual(write_tag, write_accepted.tag)
       self.assertTrue(write_accepted.write_accepted)
 
       client_call.read(read_tag)
-      read_accepted = self.client_completion_queue.get(_FUTURE)
+      read_accepted = self.client_events.get()
       self.assertIsNotNone(read_accepted)
       self.assertEqual(_low.Event.Kind.READ_ACCEPTED, read_accepted.kind)
       self.assertEqual(read_tag, read_accepted.tag)
@@ -209,14 +222,14 @@ class EchoTest(unittest.TestCase):
       client_data.append(read_accepted.bytes)
 
     client_call.complete(complete_tag)
-    complete_accepted = self.client_completion_queue.get(_FUTURE)
+    complete_accepted = self.client_events.get()
     self.assertIsNotNone(complete_accepted)
     self.assertIs(complete_accepted.kind, _low.Event.Kind.COMPLETE_ACCEPTED)
     self.assertIs(complete_accepted.tag, complete_tag)
     self.assertIs(complete_accepted.complete_accepted, True)
 
     server_call.read(read_tag)
-    read_accepted = self.server_completion_queue.get(_FUTURE)
+    read_accepted = self.server_events.get()
     self.assertIsNotNone(read_accepted)
     self.assertEqual(_low.Event.Kind.READ_ACCEPTED, read_accepted.kind)
     self.assertEqual(read_tag, read_accepted.tag)
@@ -228,8 +241,8 @@ class EchoTest(unittest.TestCase):
                              server_trailing_binary_metadata_value)
 
     server_call.status(_low.Status(_low.Code.OK, details), status_tag)
-    server_terminal_event_one = self.server_completion_queue.get(_FUTURE)
+    server_terminal_event_one = self.server_events.get()
-    server_terminal_event_two = self.server_completion_queue.get(_FUTURE)
+    server_terminal_event_two = self.server_events.get()
     if server_terminal_event_one.kind == _low.Event.Kind.COMPLETE_ACCEPTED:
       status_accepted = server_terminal_event_one
       rpc_accepted = server_terminal_event_two
@@ -246,8 +259,8 @@ class EchoTest(unittest.TestCase):
     self.assertEqual(_low.Status(_low.Code.OK, ''), rpc_accepted.status)
 
     client_call.read(read_tag)
-    client_terminal_event_one = self.client_completion_queue.get(_FUTURE)
+    client_terminal_event_one = self.client_events.get()
-    client_terminal_event_two = self.client_completion_queue.get(_FUTURE)
+    client_terminal_event_two = self.client_events.get()
     if client_terminal_event_one.kind == _low.Event.Kind.READ_ACCEPTED:
       read_accepted = client_terminal_event_one
       finish_accepted = client_terminal_event_two
@@ -303,22 +316,26 @@ class CancellationTest(unittest.TestCase):
     self.server = _low.Server(self.server_completion_queue)
     port = self.server.add_http2_addr('[::]:0')
     self.server.start()
+    self.server_events = Queue.Queue()
+    self.server_completion_queue_thread = threading.Thread(
+        target=_drive_completion_queue,
+        args=(self.server_completion_queue, self.server_events))
+    self.server_completion_queue_thread.start()
 
     self.client_completion_queue = _low.CompletionQueue()
     self.channel = _low.Channel('%s:%d' % (self.host, port), None)
+    self.client_events = Queue.Queue()
+    self.client_completion_queue_thread = threading.Thread(
+        target=_drive_completion_queue,
+        args=(self.client_completion_queue, self.client_events))
+    self.client_completion_queue_thread.start()
 
   def tearDown(self):
     self.server.stop()
     self.server_completion_queue.stop()
     self.client_completion_queue.stop()
-    while True:
+    self.server_completion_queue_thread.join()
-      event = self.server_completion_queue.get(0)
+    self.client_completion_queue_thread.join()
-      if event is not None and event.kind is _low.Event.Kind.STOP:
-        break
-    while True:
-      event = self.client_completion_queue.get(0)
-      if event is not None and event.kind is _low.Event.Kind.STOP:
-        break
     del self.server
 
   def testCancellation(self):
@@ -340,29 +357,29 @@ class CancellationTest(unittest.TestCase):
     client_call.invoke(self.client_completion_queue, metadata_tag, finish_tag)
 
     self.server.service(service_tag)
-    service_accepted = self.server_completion_queue.get(_FUTURE)
+    service_accepted = self.server_events.get()
     server_call = service_accepted.service_acceptance.call
 
     server_call.accept(self.server_completion_queue, finish_tag)
     server_call.premetadata()
 
-    metadata_accepted = self.client_completion_queue.get(_FUTURE)
+    metadata_accepted = self.client_events.get()
     self.assertIsNotNone(metadata_accepted)
 
     for datum in test_data:
       client_call.write(datum, write_tag)
-      write_accepted = self.client_completion_queue.get(_FUTURE)
+      write_accepted = self.client_events.get()
 
       server_call.read(read_tag)
-      read_accepted = self.server_completion_queue.get(_FUTURE)
+      read_accepted = self.server_events.get()
       server_data.append(read_accepted.bytes)
 
       server_call.write(read_accepted.bytes, write_tag)
-      write_accepted = self.server_completion_queue.get(_FUTURE)
+      write_accepted = self.server_events.get()
       self.assertIsNotNone(write_accepted)
 
       client_call.read(read_tag)
-      read_accepted = self.client_completion_queue.get(_FUTURE)
+      read_accepted = self.client_events.get()
       client_data.append(read_accepted.bytes)
 
     client_call.cancel()
@@ -373,8 +390,8 @@ class CancellationTest(unittest.TestCase):
 
     server_call.read(read_tag)
 
-    server_terminal_event_one = self.server_completion_queue.get(_FUTURE)
+    server_terminal_event_one = self.server_events.get()
-    server_terminal_event_two = self.server_completion_queue.get(_FUTURE)
+    server_terminal_event_two = self.server_events.get()
     if server_terminal_event_one.kind == _low.Event.Kind.READ_ACCEPTED:
       read_accepted = server_terminal_event_one
       rpc_accepted = server_terminal_event_two
@@ -388,7 +405,7 @@ class CancellationTest(unittest.TestCase):
     self.assertEqual(_low.Event.Kind.FINISH, rpc_accepted.kind)
     self.assertEqual(_low.Status(_low.Code.CANCELLED, ''), rpc_accepted.status)
 
-    finish_event = self.client_completion_queue.get(_FUTURE)
+    finish_event = self.client_events.get()
     self.assertEqual(_low.Event.Kind.FINISH, finish_event.kind)
     self.assertEqual(_low.Status(_low.Code.CANCELLED, 'Cancelled'), 
                                  finish_event.status)