Add a "transport" field to links.Ticket

This will be used for communication of transport-specific values and
objects up to applications.

src/python/grpcio/grpc/_links/invocation.py

@@ -101,7 +101,7 @@ class _Kernel(object):
     else:
       ticket = links.Ticket(
           operation_id, rpc_state.sequence_number, None, None, None, None, 1,
-          None, None, None, None, None, None)
+          None, None, None, None, None, None, None)
       rpc_state.sequence_number += 1
       self._relay.add_value(ticket)
       rpc_state.low_write = _LowWrite.OPEN
@@ -118,7 +118,7 @@ class _Kernel(object):
       ticket = links.Ticket(
           operation_id, rpc_state.sequence_number, None, None, None, None, None,
           None, rpc_state.response_deserializer(event.bytes), None, None, None,
-          None)
+          None, None)
       rpc_state.sequence_number += 1
       self._relay.add_value(ticket)
 
@@ -129,7 +129,7 @@ class _Kernel(object):
     ticket = links.Ticket(
         operation_id, rpc_state.sequence_number, None, None,
         links.Ticket.Subscription.FULL, None, None, event.metadata, None, None,
-        None, None, None)
+        None, None, None, None)
     rpc_state.sequence_number += 1
     self._relay.add_value(ticket)
 
@@ -146,7 +146,7 @@ class _Kernel(object):
     ticket = links.Ticket(
         operation_id, rpc_state.sequence_number, None, None, None, None, None,
         None, None, event.metadata, event.status.code, event.status.details,
-        termination)
+        termination, None)
     rpc_state.sequence_number += 1
     self._relay.add_value(ticket)
 

src/python/grpcio/grpc/_links/service.py

@@ -131,7 +131,7 @@ class _Kernel(object):
     ticket = links.Ticket(
         call, 0, group, method, links.Ticket.Subscription.FULL,
         service_acceptance.deadline - time.time(), None, event.metadata, None,
-        None, None, None, None)
+        None, None, None, None, 'TODO: Service Context Object!')
     self._relay.add_value(ticket)
 
   def _on_read_event(self, event):
@@ -157,7 +157,7 @@ class _Kernel(object):
         # rpc_state.read = _Read.AWAITING_ALLOWANCE
     ticket = links.Ticket(
         call, rpc_state.sequence_number, None, None, None, None, None, None,
-        payload, None, None, None, termination)
+        payload, None, None, None, termination, None)
     rpc_state.sequence_number += 1
     self._relay.add_value(ticket)
 
@@ -176,7 +176,7 @@ class _Kernel(object):
     else:
       ticket = links.Ticket(
           call, rpc_state.sequence_number, None, None, None, None, 1, None,
-          None, None, None, None, None)
+          None, None, None, None, None, None)
       rpc_state.sequence_number += 1
       self._relay.add_value(ticket)
       rpc_state.low_write = _LowWrite.OPEN
@@ -198,7 +198,7 @@ class _Kernel(object):
       termination = links.Ticket.Termination.TRANSMISSION_FAILURE
     ticket = links.Ticket(
         call, rpc_state.sequence_number, None, None, None, None, None, None,
-        None, None, None, None, termination)
+        None, None, None, None, termination, None)
     rpc_state.sequence_number += 1
     self._relay.add_value(ticket)
 
@@ -259,7 +259,7 @@ class _Kernel(object):
             termination = links.Ticket.Termination.COMPLETION
           ticket = links.Ticket(
               call, rpc_state.sequence_number, None, None, None, None, None,
-              None, payload, None, None, None, termination)
+              None, payload, None, None, None, termination, None)
           rpc_state.sequence_number += 1
           self._relay.add_value(ticket)
 

src/python/grpcio/grpc/framework/core/_transmission.py

@@ -107,7 +107,7 @@ class TransmissionManager(_interfaces.TransmissionManager):
           return links.Ticket(
               self._operation_id, self._lowest_unused_sequence_number, None,
               None, None, None, None, None, None, None, None, None,
-              termination)
+              termination, None)
 
     action = False
     # TODO(nathaniel): Support other subscriptions.
@@ -144,7 +144,7 @@ class TransmissionManager(_interfaces.TransmissionManager):
       ticket = links.Ticket(
           self._operation_id, self._lowest_unused_sequence_number, None, None,
           local_subscription, timeout, allowance, initial_metadata, payload,
-          terminal_metadata, code, message, termination)
+          terminal_metadata, code, message, termination, None)
       self._lowest_unused_sequence_number += 1
       return ticket
     else:
@@ -191,7 +191,7 @@ class TransmissionManager(_interfaces.TransmissionManager):
     ticket = links.Ticket(
         self._operation_id, 0, group, method, subscription, timeout, allowance,
         initial_metadata, payload, terminal_metadata, code, message,
-        termination)
+        termination, None)
     self._lowest_unused_sequence_number = 1
     self._transmit(ticket)
 
@@ -236,7 +236,7 @@ class TransmissionManager(_interfaces.TransmissionManager):
         ticket = links.Ticket(
             self._operation_id, self._lowest_unused_sequence_number, None, None,
             None, None, allowance, effective_initial_metadata, ticket_payload,
-            terminal_metadata, code, message, termination)
+            terminal_metadata, code, message, termination, None)
         self._lowest_unused_sequence_number += 1
         self._transmit(ticket)
 
@@ -247,7 +247,7 @@ class TransmissionManager(_interfaces.TransmissionManager):
     else:
       ticket = links.Ticket(
           self._operation_id, self._lowest_unused_sequence_number, None, None,
-          None, timeout, None, None, None, None, None, None, None)
+          None, timeout, None, None, None, None, None, None, None, None)
       self._lowest_unused_sequence_number += 1
       self._transmit(ticket)
 
@@ -268,7 +268,7 @@ class TransmissionManager(_interfaces.TransmissionManager):
       ticket = links.Ticket(
           self._operation_id, self._lowest_unused_sequence_number, None, None,
           None, None, None, None, payload, terminal_metadata, code, message,
-          termination)
+          termination, None)
       self._lowest_unused_sequence_number += 1
       self._transmit(ticket)
 
@@ -290,5 +290,5 @@ class TransmissionManager(_interfaces.TransmissionManager):
           ticket = links.Ticket(
               self._operation_id, self._lowest_unused_sequence_number, None,
               None, None, None, None, None, None, None, None, None,
-              termination)
+              termination, None)
           self._transmit(ticket)

src/python/grpcio/grpc/framework/interfaces/links/links.py

@@ -34,12 +34,30 @@ import collections
 import enum
 
 
+class Transport(collections.namedtuple('Transport', ('kind', 'value',))):
+  """A sum type for handles to an underlying transport system.
+
+  Attributes:
+    kind: A Kind value identifying the kind of value being passed to or from
+      the underlying transport.
+    value: The value being passed through RPC Framework between the high-level
+      application and the underlying transport.
+  """
+
+  @enum.unique
+  class Kind(enum.Enum):
+    CALL_OPTION = 'call option'
+    SERVICER_CONTEXT = 'servicer context'
+    INVOCATION_CONTEXT = 'invocation context'
+
+
 class Ticket(
     collections.namedtuple(
         'Ticket',
-        ['operation_id', 'sequence_number', 'group', 'method', 'subscription',
+        ('operation_id', 'sequence_number', 'group', 'method', 'subscription',
          'timeout', 'allowance', 'initial_metadata', 'payload',
-         'terminal_metadata', 'code', 'message', 'termination'])):
+         'terminal_metadata', 'code', 'message', 'termination',
+         'transport',))):
   """A sum type for all values sent from a front to a back.
 
   Attributes:
@@ -81,6 +99,8 @@ class Ticket(
     termination: A Termination value describing the end of the operation, or
       None if the operation has not yet terminated. If set, no further tickets
       may be sent in the same direction.
+    transport: A Transport value or None, with further semantics being a matter
+      between high-level application and underlying transport.
   """
 
   @enum.unique

src/python/grpcio_test/grpc_test/_links/_lonely_invocation_link_test.py

@@ -66,7 +66,7 @@ class LonelyInvocationLinkTest(unittest.TestCase):
     ticket = links.Ticket(
         test_operation_id, 0, test_group, test_method,
         links.Ticket.Subscription.FULL, test_constants.SHORT_TIMEOUT, 1, None,
-        None, None, None, None, termination)
+        None, None, None, None, termination, None)
     invocation_link.accept_ticket(ticket)
     invocation_link_mate.block_until_tickets_satisfy(test_cases.terminated)
 

src/python/grpcio_test/grpc_test/_links/_transmission_test.py

@@ -128,14 +128,14 @@ class RoundTripTest(unittest.TestCase):
     invocation_ticket = links.Ticket(
         test_operation_id, 0, test_group, test_method,
         links.Ticket.Subscription.FULL, test_constants.LONG_TIMEOUT, None, None,
-        None, None, None, None, links.Ticket.Termination.COMPLETION)
+        None, None, None, None, links.Ticket.Termination.COMPLETION, None)
     invocation_link.accept_ticket(invocation_ticket)
     service_mate.block_until_tickets_satisfy(test_cases.terminated)
 
     service_ticket = links.Ticket(
         service_mate.tickets()[-1].operation_id, 0, None, None, None, None,
         None, None, None, None, test_code, test_message,
-        links.Ticket.Termination.COMPLETION)
+        links.Ticket.Termination.COMPLETION, None)
     service_link.accept_ticket(service_ticket)
     invocation_mate.block_until_tickets_satisfy(test_cases.terminated)
 
@@ -174,33 +174,34 @@ class RoundTripTest(unittest.TestCase):
     invocation_ticket = links.Ticket(
         test_operation_id, 0, test_group, test_method,
         links.Ticket.Subscription.FULL, test_constants.LONG_TIMEOUT, None, None,
-        None, None, None, None, None)
+        None, None, None, None, None, None)
     invocation_link.accept_ticket(invocation_ticket)
     requests = scenario.requests()
     for request_index, request in enumerate(requests):
       request_ticket = links.Ticket(
           test_operation_id, 1 + request_index, None, None, None, None, 1, None,
-          request, None, None, None, None)
+          request, None, None, None, None, None)
       invocation_link.accept_ticket(request_ticket)
       service_mate.block_until_tickets_satisfy(
           test_cases.at_least_n_payloads_received_predicate(1 + request_index))
       response_ticket = links.Ticket(
           service_mate.tickets()[0].operation_id, request_index, None, None,
           None, None, 1, None, scenario.response_for_request(request), None,
-          None, None, None)
+          None, None, None, None)
       service_link.accept_ticket(response_ticket)
       invocation_mate.block_until_tickets_satisfy(
           test_cases.at_least_n_payloads_received_predicate(1 + request_index))
     request_count = len(requests)
     invocation_completion_ticket = links.Ticket(
         test_operation_id, request_count + 1, None, None, None, None, None,
-        None, None, None, None, None, links.Ticket.Termination.COMPLETION)
+        None, None, None, None, None, links.Ticket.Termination.COMPLETION,
+        None)
     invocation_link.accept_ticket(invocation_completion_ticket)
     service_mate.block_until_tickets_satisfy(test_cases.terminated)
     service_completion_ticket = links.Ticket(
         service_mate.tickets()[0].operation_id, request_count, None, None, None,
         None, None, None, None, None, test_code, test_message,
-        links.Ticket.Termination.COMPLETION)
+        links.Ticket.Termination.COMPLETION, None)
     service_link.accept_ticket(service_completion_ticket)
     invocation_mate.block_until_tickets_satisfy(test_cases.terminated)
 

src/python/grpcio_test/grpc_test/framework/interfaces/links/test_cases.py

@@ -300,7 +300,7 @@ class TransmissionTest(object):
         invocation_operation_id, 0, _TRANSMISSION_GROUP, _TRANSMISSION_METHOD,
         links.Ticket.Subscription.FULL, timeout, 0, invocation_initial_metadata,
         invocation_payload, invocation_terminal_metadata, invocation_code,
-        invocation_message, links.Ticket.Termination.COMPLETION)
+        invocation_message, links.Ticket.Termination.COMPLETION, None)
     self._invocation_link.accept_ticket(original_invocation_ticket)
 
     self._service_mate.block_until_tickets_satisfy(
@@ -317,7 +317,7 @@ class TransmissionTest(object):
         service_operation_id, 0, None, None, links.Ticket.Subscription.FULL,
         timeout, 0, service_initial_metadata, service_payload,
         service_terminal_metadata, service_code, service_message,
-        links.Ticket.Termination.COMPLETION)
+        links.Ticket.Termination.COMPLETION, None)
     self._service_link.accept_ticket(original_service_ticket)
     self._invocation_mate.block_until_tickets_satisfy(terminated)
     self._assert_is_valid_service_sequence(

src/python/grpcio_test/grpc_test/framework/interfaces/links/test_utilities.py

@@ -64,7 +64,7 @@ def _safe_for_log_ticket(ticket):
         ticket.allowance, ticket.initial_metadata,
         '<payload of length {}>'.format(payload_length),
         ticket.terminal_metadata, ticket.code, ticket.message,
-        ticket.termination)
+        ticket.termination, None)
 
 
 class RecordingLink(links.Link):