private void OnResolverResult(ResolverResult result)
{
if (_balancer == null)
{
throw new InvalidOperationException($"Load balancer not configured.");
}
var channelStatus = result.Status;
// https://github.com/grpc/proposal/blob/master/A21-service-config-error-handling.md
// Additionally, only use resolved service config if not disabled.
LoadBalancingConfig?loadBalancingConfig = null;
if (!DisableResolverServiceConfig)
{
ServiceConfig?workingServiceConfig = null;
if (result.ServiceConfig == null)
{
// Step 4 and 5
if (result.ServiceConfigStatus == null)
{
// Step 5: Use default service config if none is provided.
_previousServiceConfig = DefaultServiceConfig;
workingServiceConfig = DefaultServiceConfig;
}
else
{
// Step 4
if (_previousServiceConfig == null)
{
// Step 4.ii: If no config was provided or set previously, then treat resolution as a failure.
channelStatus = result.ServiceConfigStatus.GetValueOrDefault();
}
else
{
// Step 4.i: Continue using previous service config if it was set and a new one is not provided.
workingServiceConfig = _previousServiceConfig;
ConnectionManagerLog.ResolverServiceConfigFallback(Logger, result.ServiceConfigStatus.GetValueOrDefault());
}
}
}
else
{
// Step 3: Use provided service config if it is set.
workingServiceConfig = result.ServiceConfig;
_previousServiceConfig = result.ServiceConfig;
}
if (workingServiceConfig?.LoadBalancingConfigs.Count > 0)
{
if (!ChildHandlerLoadBalancer.TryGetValidServiceConfigFactory(workingServiceConfig.LoadBalancingConfigs, LoadBalancerFactories, out loadBalancingConfig, out var _))
{
ConnectionManagerLog.ResolverUnsupportedLoadBalancingConfig(Logger, workingServiceConfig.LoadBalancingConfigs);
}
}
}
else
{
if (result.ServiceConfig != null)
{
ConnectionManagerLog.ResolverServiceConfigNotUsed(Logger);
}
}
var state = new ChannelState(
channelStatus,
result.Addresses,
loadBalancingConfig,
BalancerAttributes.Empty);
lock (_lock)
{
_balancer.UpdateChannelState(state);
_resolverStartedTcs.TrySetResult(null);
}
}
