xds: Put channel in TRANSIENT_FAILURE when CDS resource is removed.

src/core/ext/filters/client_channel/lb_policy/xds/cds.cc

@@ -215,14 +215,10 @@ void CdsLb::ClusterWatcher::OnError(grpc_error* error) {
 }
 
 void CdsLb::ClusterWatcher::OnResourceDoesNotExist() {
-  gpr_log(GPR_ERROR, "[cdslb %p] CDS resource for %s does not exist",
+  gpr_log(GPR_ERROR,
+          "[cdslb %p] CDS resource for %s does not exist -- reporting "
+          "TRANSIENT_FAILURE",
           parent_.get(), parent_->config_->cluster().c_str());
-  // Go into TRANSIENT_FAILURE if we have not yet created the child
-  // policy (i.e., we have not yet received data from xds).  Otherwise,
-  // we keep running with the data we had previously.
-  // TODO(roth): Once traffic splitting is implemented, this should be
-  // fixed to report TRANSIENT_FAILURE unconditionally.
-  if (parent_->child_policy_ == nullptr) {
   parent_->channel_control_helper()->UpdateState(
       GRPC_CHANNEL_TRANSIENT_FAILURE,
       absl::make_unique<TransientFailurePicker>(
@@ -231,7 +227,6 @@ void CdsLb::ClusterWatcher::OnResourceDoesNotExist() {
                            "\" does not exist")
                   .c_str())));
 }
-}
 
 //
 // CdsLb::Helper

src/core/ext/filters/client_channel/lb_policy/xds/eds.cc

@@ -342,21 +342,16 @@ class EdsLb::EndpointWatcher : public XdsClient::EndpointWatcherInterface {
   }
 
   void OnResourceDoesNotExist() override {
-    gpr_log(GPR_ERROR, "[edslb %p] EDS resource does not exist",
+    gpr_log(
+        GPR_ERROR,
+        "[edslb %p] EDS resource does not exist -- reporting TRANSIENT_FAILURE",
         eds_policy_.get());
-    // Go into TRANSIENT_FAILURE if we have not yet created the child
-    // policy (i.e., we have not yet received data from xds).  Otherwise,
-    // we keep running with the data we had previously.
-    // TODO(roth): Once traffic splitting is implemented, this should be
-    // fixed to report TRANSIENT_FAILURE unconditionally.
-    if (eds_policy_->child_policy_ == nullptr) {
     eds_policy_->channel_control_helper()->UpdateState(
         GRPC_CHANNEL_TRANSIENT_FAILURE,
         absl::make_unique<TransientFailurePicker>(
             GRPC_ERROR_CREATE_FROM_STATIC_STRING(
                 "EDS resource does not exist")));
   }
-  }
 
  private:
   RefCountedPtr<EdsLb> eds_policy_;

test/cpp/end2end/xds_end2end_test.cc

@@ -1908,7 +1908,7 @@ TEST_P(XdsResolverOnlyTest, ListenerRemoved) {
       AdsServiceImpl::BuildEdsResource(args));
   // We need to wait for all backends to come online.
   WaitForAllBackends();
-  // Unset CDS resource.
+  // Unset LDS resource.
   balancers_[0]->ads_service()->UnsetResource(kLdsTypeUrl,
                                               kDefaultResourceName);
   // Wait for RPCs to start failing.
@@ -1921,7 +1921,7 @@ TEST_P(XdsResolverOnlyTest, ListenerRemoved) {
             AdsServiceImpl::ResponseState::ACKED);
 }
 
-// Tests that things keep workng if the cluster resource disappears.
+// Tests that we go into TRANSIENT_FAILURE if the Cluster disappears.
 TEST_P(XdsResolverOnlyTest, ClusterRemoved) {
   SetNextResolution({});
   SetNextResolutionForLbChannelAllBalancers();
@@ -1935,8 +1935,11 @@ TEST_P(XdsResolverOnlyTest, ClusterRemoved) {
   // Unset CDS resource.
   balancers_[0]->ads_service()->UnsetResource(kCdsTypeUrl,
                                               kDefaultResourceName);
-  // Make sure RPCs are still succeeding.
-  CheckRpcSendOk(100 * num_backends_);
+  // Wait for RPCs to start failing.
+  do {
+  } while (SendRpc(RpcOptions(), nullptr).ok());
+  // Make sure RPCs are still failing.
+  CheckRpcSendFailure(1000);
   // Make sure we ACK'ed the update.
   EXPECT_EQ(balancers_[0]->ads_service()->cds_response_state().state,
             AdsServiceImpl::ResponseState::ACKED);