protected static Channel TryGetChannelFromLoadBalancer(Channel lbChannel,
ChannelCredentials credentials,
string serviceName,
int maxMesssageLength)
{
ServiceDiscoveryGrpc.ServiceDiscoveryGrpcClient lbClient =
new ServiceDiscoveryGrpc.ServiceDiscoveryGrpcClient(lbChannel);
DiscoverServicesResponse lbResponse = lbClient.DiscoverTopServices(
new DiscoverServicesRequest
{
ServiceName = serviceName,
MaxCount = 1
});
if (lbResponse.ServiceLocations.Count > 0)
{
ServiceLocationMsg serviceLocation = lbResponse.ServiceLocations[0];
Channel result = GrpcUtils.CreateChannel(serviceLocation.HostName,
serviceLocation.Port, credentials,
maxMesssageLength);
_msg.DebugFormat("The load balancer is suggesting {0}", result.ResolvedTarget);
return(result);
}
// Assumption: A load balancer is never also serving real requests -> lets not use it at all!
_msg.Debug("The load balancer has no service locations available.");
return(null);
}
private IEnumerable <ServiceLocationMsg> UseTopServices(
IEnumerable <QualifiedService> qualifiedServices,
int maxCount = -1)
{
int resultCount = 0;
foreach (QualifiedService qualifiedService in qualifiedServices)
{
if (maxCount > 0 && resultCount >= maxCount)
{
yield break;
}
ServiceLocationMsg serviceLocationMsg =
ToServiceLocationMsg(qualifiedService.ServiceLocation);
// And add it to the least-recently-used queue
qualifiedService.LastUsed = DateTime.Now;
_recentlyUsedServices.Enqueue(qualifiedService);
yield return(serviceLocationMsg);
resultCount++;
}
}
private static ServiceLocationMsg ToServiceLocationMsg(ServiceLocation serviceLocation)
{
ServiceLocationMsg serviceLocationMsg = new ServiceLocationMsg
{
Scope = serviceLocation.Scope,
ServiceName = serviceLocation.ServiceName,
HostName = serviceLocation.HostName,
Port = serviceLocation.Port
};
return(serviceLocationMsg);
}
private static IEnumerable <ServiceLocationMsg> ToServiceLocationMessages(
IEnumerable <ServiceLocation> serviceLocations,
int maxCount = -1)
{
int resultCount = 0;
foreach (ServiceLocation serviceLocation in serviceLocations)
{
if (maxCount > 0 && resultCount >= maxCount)
{
yield break;
}
ServiceLocationMsg serviceLocationMsg = ToServiceLocationMsg(serviceLocation);
yield return(serviceLocationMsg);
resultCount++;
}
}
public void CanDiscoverSingleService()
{
DeregisterServices(_host127001, _startPort127001);
ServiceDiscoveryGrpc.ServiceDiscoveryGrpcClient client = GetClient();
DiscoverServicesResponse response = client.DiscoverServices(
new DiscoverServicesRequest
{
ServiceName = _serviceName,
MaxCount = 1
});
Assert.AreEqual(1, response.ServiceLocations.Count);
ServiceLocationMsg serviceLocation = response.ServiceLocations[0];
Assert.AreEqual(_serviceName, serviceLocation.ServiceName);
Assert.AreEqual(_localHost, serviceLocation.HostName);
}
private static ServiceLocation ToServiceLocation(ServiceLocationMsg serviceLocationMsg)
{
return(new ServiceLocation(serviceLocationMsg.ServiceName, serviceLocationMsg.HostName,
serviceLocationMsg.Port, false));
}
