io.grpc.LoadBalancer.SubchannelPicker Java Examples

@Test
public void subchannelPickerInterceptedWithLoadRecording() {
  List<EquivalentAddressGroup> backendAddrs = createResolvedBackendAddresses(2);
  deliverResolvedAddresses(backendAddrs, "round_robin");
  FakeLoadBalancer childBalancer = (FakeLoadBalancer) childBalancers.poll();
  NoopSubchannel subchannel = childBalancer.subchannels.values().iterator().next();
  deliverSubchannelState(subchannel, ConnectivityState.READY);
  assertThat(loadRecorder.recording).isTrue();
  ArgumentCaptor<SubchannelPicker> pickerCaptor = ArgumentCaptor.forClass(null);
  verify(helper).updateBalancingState(eq(ConnectivityState.READY), pickerCaptor.capture());
  SubchannelPicker picker = pickerCaptor.getValue();
  assertThat(picker).isInstanceOf(LoadRecordingSubchannelPicker.class);
  PickResult result = picker.pickSubchannel(mock(PickSubchannelArgs.class));
  ClientStreamTracer.Factory tracerFactory = result.getStreamTracerFactory();
  assertThat(((LoadRecordingStreamTracerFactory) tracerFactory).getCounter())
      .isSameInstanceAs(counter);
  loadBalancer.shutdown();
  assertThat(childBalancer.shutdown).isTrue();
  assertThat(loadRecorder.recording).isFalse();
}
 

@Test
public void newStream_racesWithReprocessIdleMode() throws Exception {
  SubchannelPicker picker = new SubchannelPicker() {
    @Override public PickResult pickSubchannel(PickSubchannelArgs args) {
      // Assume entering idle mode raced with the pick
      delayedTransport.reprocess(null);
      // Act like IDLE LB
      return PickResult.withNoResult();
    }
  };

  // Because there is no pending stream yet, it will do nothing but save the picker.
  delayedTransport.reprocess(picker);

  ClientStream stream = delayedTransport.newStream(method, headers, callOptions);
  stream.start(streamListener);
  assertTrue(delayedTransport.hasPendingStreams());
  verify(transportListener).transportInUse(true);
}
 

@VisibleForTesting
void panic(final Throwable t) {
  if (panicMode) {
    // Preserve the first panic information
    return;
  }
  panicMode = true;
  cancelIdleTimer(/* permanent= */ true);
  shutdownNameResolverAndLoadBalancer(false);
  final class PanicSubchannelPicker extends SubchannelPicker {
    private final PickResult panicPickResult =
        PickResult.withDrop(
            Status.INTERNAL.withDescription("Panic! This is a bug!").withCause(t));

    @Override
    public PickResult pickSubchannel(PickSubchannelArgs args) {
      return panicPickResult;
    }
  }

  updateSubchannelPicker(new PanicSubchannelPicker());
  channelLogger.log(ChannelLogLevel.ERROR, "PANIC! Entering TRANSIENT_FAILURE");
  channelStateManager.gotoState(TRANSIENT_FAILURE);
}
 

@Override
public void updateBalancingState(
    final ConnectivityState newState, final SubchannelPicker newPicker) {
  checkNotNull(newState, "newState");
  checkNotNull(newPicker, "newPicker");
  final class UpdateBalancingState implements Runnable {
    @Override
    public void run() {
      if (LbHelperImpl.this != lbHelper) {
        return;
      }
      updateSubchannelPicker(newPicker);
      // It's not appropriate to report SHUTDOWN state from lb.
      // Ignore the case of newState == SHUTDOWN for now.
      if (newState != SHUTDOWN) {
        channelLogger.log(ChannelLogLevel.INFO, "Entering {0} state", newState);
        channelStateManager.gotoState(newState);
      }
    }
  }

  syncContext.execute(new UpdateBalancingState());
}
 

@Test
public void newPolicyNameTheSameAsCurrentPolicy_shouldShutdownPendingLb() {
  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[0]));
  LoadBalancer lb0 = balancers.get(lbPolicies[0]);

  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[0]));
  assertThat(balancers.get(lbPolicies[0])).isSameInstanceAs(lb0);

  Helper helper0 = helpers.get(lb0);
  SubchannelPicker picker = mock(SubchannelPicker.class);
  helper0.updateBalancingState(READY, picker);

  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[1]));
  LoadBalancer lb1 = balancers.get(lbPolicies[1]);

  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[0]));
  verify(lb1).shutdown();
  assertThat(balancers.get(lbPolicies[0])).isSameInstanceAs(lb0);

  verifyNoMoreInteractions(lb0, lb1);
}
 

@Test
public void nameResolutionSuccessAfterError() throws Exception {
  InOrder inOrder = inOrder(mockHelper);

  loadBalancer.handleNameResolutionError(Status.NOT_FOUND.withDescription("nameResolutionError"));
  inOrder.verify(mockHelper)
      .updateBalancingState(any(ConnectivityState.class), any(SubchannelPicker.class));
  verify(mockSubchannel, never()).requestConnection();

  loadBalancer.handleResolvedAddresses(
      ResolvedAddresses.newBuilder().setAddresses(servers).setAttributes(affinity).build());
  inOrder.verify(mockHelper).createSubchannel(createArgsCaptor.capture());
  CreateSubchannelArgs args = createArgsCaptor.getValue();
  assertThat(args.getAddresses()).isEqualTo(servers);
  assertThat(args.getAttributes()).isEqualTo(Attributes.EMPTY);
  inOrder.verify(mockHelper).updateBalancingState(eq(CONNECTING), pickerCaptor.capture());
  verify(mockSubchannel).requestConnection();

  assertEquals(mockSubchannel, pickerCaptor.getValue().pickSubchannel(mockArgs)
      .getSubchannel());

  assertEquals(pickerCaptor.getValue().pickSubchannel(mockArgs),
      pickerCaptor.getValue().pickSubchannel(mockArgs));

  verifyNoMoreInteractions(mockHelper);
}
 

@Test
public void clusterWatcher_resourceNotExist() {
  ResolvedAddresses resolvedAddresses = ResolvedAddresses.newBuilder()
      .setAddresses(ImmutableList.<EquivalentAddressGroup>of())
      .setAttributes(Attributes.newBuilder()
          .set(XdsAttributes.XDS_CLIENT_POOL, xdsClientPool)
          .build())
      .setLoadBalancingPolicyConfig(new CdsConfig("foo.googleapis.com"))
      .build();
  cdsLoadBalancer.handleResolvedAddresses(resolvedAddresses);

  ArgumentCaptor<ClusterWatcher> clusterWatcherCaptor = ArgumentCaptor.forClass(null);
  verify(xdsClient).watchClusterData(eq("foo.googleapis.com"), clusterWatcherCaptor.capture());

  ClusterWatcher clusterWatcher = clusterWatcherCaptor.getValue();
  ArgumentCaptor<SubchannelPicker> pickerCaptor = ArgumentCaptor.forClass(null);
  clusterWatcher.onResourceDoesNotExist("foo.googleapis.com");
  assertThat(edsLoadBalancers).isEmpty();
  verify(helper).updateBalancingState(eq(TRANSIENT_FAILURE), pickerCaptor.capture());
  PickResult result = pickerCaptor.getValue().pickSubchannel(mock(PickSubchannelArgs.class));
  assertThat(result.getStatus().getCode()).isEqualTo(Code.UNAVAILABLE);
  assertThat(result.getStatus().getDescription())
      .isEqualTo("Resource foo.googleapis.com is unavailable");
}
 

@Test
public void reprocess_NoPendingStream() {
  SubchannelPicker picker = mock(SubchannelPicker.class);
  AbstractSubchannel subchannel = mock(AbstractSubchannel.class);
  when(subchannel.getInternalSubchannel()).thenReturn(mockInternalSubchannel);
  when(picker.pickSubchannel(any(PickSubchannelArgs.class))).thenReturn(
      PickResult.withSubchannel(subchannel));
  when(mockRealTransport.newStream(any(MethodDescriptor.class), any(Metadata.class),
          any(CallOptions.class))).thenReturn(mockRealStream);
  delayedTransport.reprocess(picker);
  verifyNoMoreInteractions(picker);
  verifyNoMoreInteractions(transportListener);

  // Though picker was not originally used, it will be saved and serve future streams.
  ClientStream stream = delayedTransport.newStream(method, headers, CallOptions.DEFAULT);
  verify(picker).pickSubchannel(new PickSubchannelArgsImpl(method, headers, CallOptions.DEFAULT));
  verify(mockInternalSubchannel).obtainActiveTransport();
  assertSame(mockRealStream, stream);
}
 

@Test
public void handleResolvedAddressGroups_keepOldBalancer() {
  final List<EquivalentAddressGroup> servers =
      Collections.singletonList(
          new EquivalentAddressGroup(new SocketAddress(){}, Attributes.EMPTY));
  Helper helper = new TestHelper() {
    @Override
    public Subchannel createSubchannel(List<EquivalentAddressGroup> addrs, Attributes attrs) {
      assertThat(addrs).isEqualTo(servers);
      return new TestSubchannel(addrs, attrs);
    }

    @Override
    public void updateBalancingState(ConnectivityState newState, SubchannelPicker newPicker) {
      // noop
    }
  };
  AutoConfiguredLoadBalancer lb =
      (AutoConfiguredLoadBalancer) lbf.newLoadBalancer(helper);
  LoadBalancer oldDelegate = lb.getDelegate();

  lb.handleResolvedAddressGroups(servers, Attributes.EMPTY);

  assertThat(lb.getDelegate()).isSameAs(oldDelegate);
}
 

@Override
public void updateBalancingState(
    final ConnectivityState newState, final SubchannelPicker newPicker) {
  checkNotNull(newState, "newState");
  checkNotNull(newPicker, "newPicker");
  logWarningIfNotInSyncContext("updateBalancingState()");
  final class UpdateBalancingState implements Runnable {
    @Override
    public void run() {
      if (LbHelperImpl.this != lbHelper) {
        return;
      }
      updateSubchannelPicker(newPicker);
      // It's not appropriate to report SHUTDOWN state from lb.
      // Ignore the case of newState == SHUTDOWN for now.
      if (newState != SHUTDOWN) {
        channelLogger.log(
            ChannelLogLevel.INFO, "Entering {0} state with picker: {1}", newState, newPicker);
        channelStateManager.gotoState(newState);
      }
    }
  }

  syncContext.execute(new UpdateBalancingState());
}
 

@Test
public void transientError_withPreviousEndpointUpdateReceived() {
  deliverResolvedAddresses(null, null, fakeEndpointPickingPolicy);
  // Endpoint update received.
  ClusterLoadAssignment clusterLoadAssignment =
      buildClusterLoadAssignment(CLUSTER_NAME,
          ImmutableList.of(
              buildLocalityLbEndpoints("region1", "zone1", "subzone1",
                  ImmutableList.of(
                      buildLbEndpoint("192.168.0.1", 8080, HEALTHY, 2)),
                  1, 0)),
          ImmutableList.of(buildDropOverload("throttle", 1000)));
  deliverClusterLoadAssignments(clusterLoadAssignment);

  verify(helper, never()).updateBalancingState(
      eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));

  // XdsClient stream receives an error.
  responseObserver.onError(new RuntimeException("fake error"));
  verify(helper, never()).updateBalancingState(
      eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
}
 

@Test
public void requestConnectionPicker() throws Exception {
  loadBalancer.handleResolvedAddresses(
      ResolvedAddresses.newBuilder().setAddresses(servers).setAttributes(affinity).build());

  InOrder inOrder = inOrder(mockHelper, mockSubchannel);
  inOrder.verify(mockSubchannel).start(stateListenerCaptor.capture());
  SubchannelStateListener stateListener = stateListenerCaptor.getValue();
  inOrder.verify(mockHelper).updateBalancingState(eq(CONNECTING), any(SubchannelPicker.class));
  inOrder.verify(mockSubchannel).requestConnection();

  stateListener.onSubchannelState(ConnectivityStateInfo.forNonError(IDLE));
  inOrder.verify(mockHelper).updateBalancingState(eq(IDLE), pickerCaptor.capture());

  SubchannelPicker picker = pickerCaptor.getValue();

  // Calling pickSubchannel() twice gave the same result
  assertEquals(picker.pickSubchannel(mockArgs), picker.pickSubchannel(mockArgs));

  // But the picker calls requestConnection() only once
  inOrder.verify(mockSubchannel).requestConnection();

  verify(mockSubchannel, times(2)).requestConnection();
}
 

private void updatePicker(
    @Nullable ConnectivityState state,  List<WeightedChildPicker> childPickers) {
  SubchannelPicker picker;
  if (childPickers.isEmpty()) {
    if (state == TRANSIENT_FAILURE) {
      picker = new ErrorPicker(Status.UNAVAILABLE); // TODO: more details in status
    } else {
      picker = XdsSubchannelPickers.BUFFER_PICKER;
    }
  } else {
    picker = new WeightedRandomPicker(childPickers);
  }

  if (!dropOverloads.isEmpty()) {
    picker = new DroppablePicker(dropOverloads, picker, random, loadStatsStore);
  }

  if (state != null) {
    helper.updateBalancingState(state, picker);
  }
}
 

ChildHelper() {
  final ClientLoadCounter counter = loadStatsStore.getLocalityCounter(locality);
  Helper delegate = new ForwardingLoadBalancerHelper() {
    @Override
    protected Helper delegate() {
      return helper;
    }

    @Override
    public void updateBalancingState(
        ConnectivityState newState, SubchannelPicker newPicker) {
      logger.log(
          XdsLogLevel.INFO,
          "Update load balancing state for locality {0} to {1}", locality, newState);
      currentChildState = newState;
      currentChildPicker =
          new LoadRecordingSubchannelPicker(
              counter,
              new MetricsObservingSubchannelPicker(new MetricsRecordingListener(counter),
                  newPicker, orcaPerRequestUtil));

      priorityManager.updatePriorityState(priorityManager.getPriority(locality));
    }

    @Override
    public String getAuthority() {
      //FIXME: This should be a new proposed field of Locality, locality_name
      return locality.getSubZone();
    }
  };

  orcaReportingHelperWrapper =
      orcaOobUtil.newOrcaReportingHelperWrapper(
          delegate, new MetricsRecordingListener(counter));
  if (metricsReportIntervalNano > 0) {
    updateMetricsReportInterval(metricsReportIntervalNano);
  }
}
 

@Test
public void requestConnection() {
  loadBalancer.handleResolvedAddressGroups(servers, affinity);
  loadBalancer.handleSubchannelState(mockSubchannel, ConnectivityStateInfo.forNonError(IDLE));
  verify(mockHelper).updateBalancingState(eq(IDLE), pickerCaptor.capture());
  SubchannelPicker picker = pickerCaptor.getValue();

  verify(mockSubchannel).requestConnection();
  picker.requestConnection();
  verify(mockSubchannel, times(2)).requestConnection();
}
 

@Test
public void stickinessEnabled_withoutStickyHeader() {
  Map<String, Object> serviceConfig = new HashMap<String, Object>();
  serviceConfig.put("stickinessMetadataKey", "my-sticky-key");
  Attributes attributes = Attributes.newBuilder()
      .set(GrpcAttributes.NAME_RESOLVER_SERVICE_CONFIG, serviceConfig).build();
  loadBalancer.handleResolvedAddressGroups(servers, attributes);
  for (Subchannel subchannel : subchannels.values()) {
    loadBalancer.handleSubchannelState(subchannel, ConnectivityStateInfo.forNonError(READY));
  }
  verify(mockHelper, times(4))
      .updateBalancingState(stateCaptor.capture(), pickerCaptor.capture());
  SubchannelPicker picker = pickerCaptor.getValue();

  doReturn(new Metadata()).when(mockArgs).getHeaders();

  List<Subchannel> allSubchannels = getList(picker);

  Subchannel sc1 = picker.pickSubchannel(mockArgs).getSubchannel();
  Subchannel sc2 = picker.pickSubchannel(mockArgs).getSubchannel();
  Subchannel sc3 = picker.pickSubchannel(mockArgs).getSubchannel();
  Subchannel sc4 = picker.pickSubchannel(mockArgs).getSubchannel();

  assertEquals(nextSubchannel(sc1, allSubchannels), sc2);
  assertEquals(nextSubchannel(sc2, allSubchannels), sc3);
  assertEquals(nextSubchannel(sc3, allSubchannels), sc1);
  assertEquals(sc4, sc1);
  verify(mockArgs, times(4)).getHeaders();
  assertNotNull(loadBalancer.getStickinessMapForTest());
  assertThat(loadBalancer.getStickinessMapForTest()).isEmpty();
}
 

@Test
public void stickinessEnabled_withStickyHeader() {
  Map<String, Object> serviceConfig = new HashMap<String, Object>();
  serviceConfig.put("stickinessMetadataKey", "my-sticky-key");
  Attributes attributes = Attributes.newBuilder()
      .set(GrpcAttributes.NAME_RESOLVER_SERVICE_CONFIG, serviceConfig).build();
  loadBalancer.handleResolvedAddressGroups(servers, attributes);
  for (Subchannel subchannel : subchannels.values()) {
    loadBalancer.handleSubchannelState(subchannel, ConnectivityStateInfo.forNonError(READY));
  }
  verify(mockHelper, times(4))
      .updateBalancingState(stateCaptor.capture(), pickerCaptor.capture());
  SubchannelPicker picker = pickerCaptor.getValue();

  Key<String> stickinessKey = Key.of("my-sticky-key", Metadata.ASCII_STRING_MARSHALLER);
  Metadata headerWithStickinessValue = new Metadata();
  headerWithStickinessValue.put(stickinessKey, "my-sticky-value");
  doReturn(headerWithStickinessValue).when(mockArgs).getHeaders();

  Subchannel sc1 = picker.pickSubchannel(mockArgs).getSubchannel();
  assertEquals(sc1, picker.pickSubchannel(mockArgs).getSubchannel());
  assertEquals(sc1, picker.pickSubchannel(mockArgs).getSubchannel());
  assertEquals(sc1, picker.pickSubchannel(mockArgs).getSubchannel());
  assertEquals(sc1, picker.pickSubchannel(mockArgs).getSubchannel());

  verify(mockArgs, atLeast(4)).getHeaders();
  assertNotNull(loadBalancer.getStickinessMapForTest());
  assertThat(loadBalancer.getStickinessMapForTest()).hasSize(1);
}
 

private static void updateBalancingStateSafely(
    final Helper helper, final ConnectivityState state, final SubchannelPicker picker) {
  helper.getSynchronizationContext().execute(
      new Runnable() {
        @Override
        public void run() {
          helper.updateBalancingState(state, picker);
        }
      });
}
 

/**
 * If a {@link SubchannelPicker} is being, or has been provided via {@link #reprocess}, the last
 * picker will be consulted.
 *
 * <p>Otherwise, if the delayed transport is not shutdown, then a {@link PendingStream} is
 * returned; if the transport is shutdown, then a {@link FailingClientStream} is returned.
 */
@Override
public final ClientStream newStream(
    MethodDescriptor<?, ?> method, Metadata headers, CallOptions callOptions) {
  try {
    PickSubchannelArgs args = new PickSubchannelArgsImpl(method, headers, callOptions);
    SubchannelPicker picker = null;
    long pickerVersion = -1;
    while (true) {
      synchronized (lock) {
        if (shutdownStatus != null) {
          return new FailingClientStream(shutdownStatus);
        }
        if (lastPicker == null) {
          return createPendingStream(args);
        }
        // Check for second time through the loop, and whether anything changed
        if (picker != null && pickerVersion == lastPickerVersion) {
          return createPendingStream(args);
        }
        picker = lastPicker;
        pickerVersion = lastPickerVersion;
      }
      PickResult pickResult = picker.pickSubchannel(args);
      ClientTransport transport = GrpcUtil.getTransportFromPickResult(pickResult,
          callOptions.isWaitForReady());
      if (transport != null) {
        return transport.newStream(
            args.getMethodDescriptor(), args.getHeaders(), args.getCallOptions());
      }
      // This picker's conclusion is "buffer".  If there hasn't been a newer picker set (possible
      // race with reprocess()), we will buffer it.  Otherwise, will try with the new picker.
    }
  } finally {
    syncContext.drain();
  }
}
 

@Test
public void pickerEmptyList() throws Exception {
  SubchannelPicker picker = new EmptyPicker(Status.UNKNOWN);

  assertEquals(null, picker.pickSubchannel(mockArgs).getSubchannel());
  assertEquals(Status.UNKNOWN,
      picker.pickSubchannel(mockArgs).getStatus());
}
 

@Test
public void updateLocalityStore_emptyEndpoints() {
  localityStore.updateLocalityStore(Collections.<Locality, LocalityLbEndpoints>emptyMap());
  assertThat(loadBalancers).hasSize(0);
  ArgumentCaptor<SubchannelPicker> pickerCaptor = ArgumentCaptor.forClass(null);
  verify(helper).updateBalancingState(eq(TRANSIENT_FAILURE), pickerCaptor.capture());
  PickResult result = pickerCaptor.getValue().pickSubchannel(mock(PickSubchannelArgs.class));
  assertThat(result.getStatus().getCode()).isEqualTo(Code.UNAVAILABLE);
}
 

/** Creates a {@link SubchannelPicker} that returns the given {@link Subchannel} on every pick. */
public static SubchannelPicker pickerOf(final Subchannel subchannel) {
  return new SubchannelPicker() {
    @Override
    public PickResult pickSubchannel(PickSubchannelArgs args) {
      return PickResult.withSubchannel(subchannel);
    }
  };
}
 

@Override
public void handleNameResolutionError(final Status error) {
  SubchannelPicker picker = new SubchannelPicker() {
    @Override
    public PickResult pickSubchannel(PickSubchannelArgs args) {
      return PickResult.withError(error.augmentDescription("handled by downstream balancer"));
    }
  };
  helper.updateBalancingState(ConnectivityState.TRANSIENT_FAILURE, picker);
}
 

@Test
public void transientFailureOnInitialResolutionError() {
  gracefulSwitchLb.handleNameResolutionError(Status.DATA_LOSS);
  ArgumentCaptor<SubchannelPicker> pickerCaptor = ArgumentCaptor.forClass(null);
  verify(mockHelper).updateBalancingState(eq(TRANSIENT_FAILURE), pickerCaptor.capture());
  SubchannelPicker picker = pickerCaptor.getValue();
  assertThat(picker.pickSubchannel(mock(PickSubchannelArgs.class)).getStatus().getCode())
      .isEqualTo(Status.Code.DATA_LOSS);
}
 

@Test
public void shutdownTriggeredWhenSwitchAndForwardedWhenSwitchLbShutdown() {
  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[0]));
  LoadBalancer lb0 = balancers.get(lbPolicies[0]);
  Helper helper0 = helpers.get(lb0);
  SubchannelPicker picker = mock(SubchannelPicker.class);
  helper0.updateBalancingState(READY, picker);

  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[1]));
  LoadBalancer lb1 = balancers.get(lbPolicies[1]);
  verify(lb1, never()).shutdown();

  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[2]));
  verify(lb1).shutdown();
  LoadBalancer lb2 = balancers.get(lbPolicies[2]);
  verify(lb0, never()).shutdown();
  helpers.get(lb2).updateBalancingState(READY, mock(SubchannelPicker.class));
  verify(lb0).shutdown();

  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[3]));
  LoadBalancer lb3 = balancers.get(lbPolicies[3]);
  verify(lb2, never()).shutdown();
  verify(lb3, never()).shutdown();

  gracefulSwitchLb.shutdown();
  verify(lb2).shutdown();
  verify(lb3).shutdown();

  verifyNoMoreInteractions(lb0, lb1, lb2, lb3);
}
 

@Test
public void updateBalancingState_triggersListener() {
  ChildPolicyWrapper childPolicyWrapper = factory.createOrGet("foo.google.com");
  ChildPolicyReportingHelper childPolicyReportingHelper = childPolicyWrapper.getHelper();
  SubchannelPicker childPicker = mock(SubchannelPicker.class);

  childPolicyReportingHelper.updateBalancingState(ConnectivityState.READY, childPicker);

  verify(childLbStatusListener).onStatusChanged(ConnectivityState.READY);
  assertThat(childPolicyWrapper.getPicker()).isEqualTo(childPicker);
  // picker governs childPickers will be reported to parent LB
  verify(helper).updateBalancingState(ConnectivityState.READY, picker);
}
 

@Test
public void transientError_noPreviousEndpointUpdateReceived() {
  deliverResolvedAddresses(null, null, fakeEndpointPickingPolicy);

  // Forwarding 20 seconds so that the xds client will deem EDS resource not available.
  fakeClock.forwardTime(20, TimeUnit.SECONDS);
  verify(helper).updateBalancingState(eq(TRANSIENT_FAILURE), any(SubchannelPicker.class));
}
 

/** Uses Subchannel connected to default target. */
private PickResult useFallback(PickSubchannelArgs args) {
  String defaultTarget = lbPolicyConfig.getRouteLookupConfig().getDefaultTarget();
  if (fallbackChildPolicyWrapper == null
      || !fallbackChildPolicyWrapper.getTarget().equals(defaultTarget)) {
    // TODO(creamsoup) wait until lb is ready
    startFallbackChildPolicy();
  }
  switch (fallbackChildPolicyWrapper.getConnectivityStateInfo().getState()) {
    case IDLE:
      // fall through
    case CONNECTING:
      return PickResult.withNoResult();
    case TRANSIENT_FAILURE:
      // fall through
    case SHUTDOWN:
      return
          PickResult
              .withError(fallbackChildPolicyWrapper.getConnectivityStateInfo().getStatus());
    case READY:
      SubchannelPicker picker = fallbackChildPolicyWrapper.getPicker();
      if (picker == null) {
        return PickResult.withNoResult();
      }
      return picker.pickSubchannel(args);
    default:
      throw new AssertionError();
  }
}
 

@Test
public void handleResolvedAddressesAndNameResolutionErrorForwardedToLatestPolicy() {
  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[0]));
  LoadBalancer lb0 = balancers.get(lbPolicies[0]);
  Helper helper0 = helpers.get(lb0);
  SubchannelPicker picker = mock(SubchannelPicker.class);
  helper0.updateBalancingState(READY, picker);

  ResolvedAddresses addresses = newFakeAddresses();
  gracefulSwitchLb.handleResolvedAddresses(addresses);
  verify(lb0).handleResolvedAddresses(addresses);
  gracefulSwitchLb.handleNameResolutionError(Status.DATA_LOSS);
  verify(lb0).handleNameResolutionError(Status.DATA_LOSS);

  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[1]));
  LoadBalancer lb1 = balancers.get(lbPolicies[1]);
  addresses = newFakeAddresses();
  gracefulSwitchLb.handleResolvedAddresses(addresses);
  verify(lb0, never()).handleResolvedAddresses(addresses);
  verify(lb1).handleResolvedAddresses(addresses);
  gracefulSwitchLb.handleNameResolutionError(Status.ALREADY_EXISTS);
  verify(lb0, never()).handleNameResolutionError(Status.ALREADY_EXISTS);
  verify(lb1).handleNameResolutionError(Status.ALREADY_EXISTS);

  gracefulSwitchLb.switchTo(lbProviders.get(lbPolicies[2]));
  verify(lb1).shutdown();
  LoadBalancer lb2 = balancers.get(lbPolicies[2]);
  addresses = newFakeAddresses();
  gracefulSwitchLb.handleResolvedAddresses(addresses);
  verify(lb0, never()).handleResolvedAddresses(addresses);
  verify(lb1, never()).handleResolvedAddresses(addresses);
  verify(lb2).handleResolvedAddresses(addresses);
  gracefulSwitchLb.handleNameResolutionError(Status.CANCELLED);
  verify(lb0, never()).handleNameResolutionError(Status.CANCELLED);
  verify(lb1, never()).handleNameResolutionError(Status.CANCELLED);
  verify(lb2).handleNameResolutionError(Status.CANCELLED);

  verifyNoMoreInteractions(lb0, lb1, lb2);
}
 

void deliverSubchannelState(final Subchannel subchannel, ConnectivityState state) {
  SubchannelPicker picker = new SubchannelPicker() {
    @Override
    public PickResult pickSubchannel(PickSubchannelArgs args) {
      return PickResult.withSubchannel(subchannel);
    }
  };
  helper.updateBalancingState(state, picker);
}