Refactor all gRPC proxy code into a single class.

appengine/swarming/swarming_bot/bot_code/remote_client_grpc.py

Index: appengine/swarming/swarming_bot/bot_code/remote_client_grpc.py
diff --git a/appengine/swarming/swarming_bot/bot_code/remote_client_grpc.py b/appengine/swarming/swarming_bot/bot_code/remote_client_grpc.py
index 8990ef17e7af4532c3043e043b71938a57211804..d2639eb05f9c976cfd006ac459f50ee954887d1d 100644
--- a/appengine/swarming/swarming_bot/bot_code/remote_client_grpc.py
+++ b/appengine/swarming/swarming_bot/bot_code/remote_client_grpc.py
@@ -10,26 +10,13 @@ import json
 import logging
 import time
 
-import grpc
 import google.protobuf.json_format
 from proto_bot import swarming_bot_pb2
 from remote_client_errors import InternalError
 from remote_client_errors import MintOAuthTokenError
 from remote_client_errors import PollError
 from utils import net
-
-
-# How long to wait for a response from the server. Keeping the same as
-# the equivalent in remote_client.py for now.
-NET_CONNECTION_TIMEOUT_SEC = 5*60
-
-
-# How many times to retry a gRPC call
-MAX_GRPC_ATTEMPTS = 30
-
-
-# Longest time to sleep between gRPC calls
-MAX_GRPC_SLEEP = 10.
+from utils import grpc_proxy
 
 
 class RemoteClientGrpc(object):
@@ -42,9 +29,8 @@ class RemoteClientGrpc(object):
 
   def __init__(self, server):
     logging.info('Communicating with host %s via gRPC', server)
+    self._proxy = grpc_proxy.Proxy(server, swarming_bot_pb2.BotServiceStub)
     self._server = server
-    self._channel = grpc.insecure_channel(server)
-    self._stub = swarming_bot_pb2.BotServiceStub(self._channel)
     self._log_is_asleep = False
 
   def is_grpc(self):
@@ -84,7 +70,7 @@ class RemoteClientGrpc(object):
     google.protobuf.json_format.ParseDict(params, request)
 
     # Perform update
-    response = call_grpc(self._stub.TaskUpdate, request)
+    response = self._proxy.call_unary('TaskUpdate', request)
     logging.debug('post_task_update() = %s', request)
     if response.error:
       raise InternalError(response.error)
@@ -97,7 +83,7 @@ class RemoteClientGrpc(object):
     request.msg = message
     logging.error('post_task_error() = %s', request)
 
-    response = call_grpc(self._stub.TaskError, request)
+    response = self._proxy.call_unary('TaskError', request)
     return response.ok
 
   def _attributes_json_to_proto(self, json_attr, msg):
@@ -111,7 +97,7 @@ class RemoteClientGrpc(object):
   def do_handshake(self, attributes):
     request = swarming_bot_pb2.HandshakeRequest()
     self._attributes_json_to_proto(attributes, request.attributes)
-    response = call_grpc(self._stub.Handshake, request)
+    response = self._proxy.call_unary('Handshake', request)
     resp = {
         'server_version': response.server_version,
         'bot_version': response.bot_version,
@@ -129,7 +115,7 @@ class RemoteClientGrpc(object):
     request = swarming_bot_pb2.PollRequest()
     self._attributes_json_to_proto(attributes, request.attributes)
     # TODO(aludwin): gRPC-specific exception handling (raise PollError).
-    response = call_grpc(self._stub.Poll, request)
+    response = self._proxy.call_unary('Poll', request)
 
     if response.cmd == swarming_bot_pb2.PollResponse.UPDATE:
       return 'update', response.version
@@ -189,7 +175,7 @@ class RemoteClientGrpc(object):
     logging.info('Updating to version: %s', bot_version)
     request = swarming_bot_pb2.BotUpdateRequest()
     request.bot_version = bot_version
-    response = call_grpc(self._stub.BotUpdate, request)
+    response = self._proxy.call_unary('BotUpdate', request)
     with open(new_zip_fn, 'wb') as f:
       f.write(response.bot_code)
 
@@ -244,18 +230,3 @@ def insert_dict_as_submessage(message, keyname, value):
   google.protobuf.json_format.Parse(json.dumps(value), sub_msg)
 
 
-def call_grpc(method, request):
-  """Retries a command a set number of times"""
-  for attempt in range(1, MAX_GRPC_ATTEMPTS+1):
-    try:
-      return method(request, timeout=NET_CONNECTION_TIMEOUT_SEC)
-    except grpc.RpcError as g:
-      if g.code() is not grpc.StatusCode.UNAVAILABLE:
-        raise
-      logging.warning('call_grpc - proxy is unavailable (attempt %d/%d)',
-                      attempt, MAX_GRPC_ATTEMPTS)
-      grpc_error = g
-      time.sleep(net.calculate_sleep_before_retry(attempt, MAX_GRPC_SLEEP))
-  # If we get here, it must be because we got (and saved) an error
-  assert grpc_error is not None
-  raise grpc_error