/// <summary>
/// Pings all servers to obtain their round-trips times and their high timestamps.
/// </summary>
public void PingTimestampsNow()
{
Stopwatch watch = new Stopwatch();
foreach (string server in configuration.SecondaryServers)
{
// if the server is not reached yet, we perform a dummy operation for it.
if (!replicas[server].IsContacted())
{
try
{
//we perform a dummy operation to get the rtt latency!
DateTimeOffset?serverTime = null;
long rtt;
if (server.EndsWith("-secondary") && configuration.PrimaryServers.Contains(server.Replace("-secondary", "")))
{
// get the server's last sync time from Azure
// this call only works on Azure secondaries
CloudBlobClient blobClient = ClientRegistry.GetCloudBlobClient(server);
watch.Restart();
ServiceStats stats = blobClient.GetServiceStats();
rtt = watch.ElapsedMilliseconds;
replicas[server].AddRtt(rtt);
if (stats.GeoReplication.LastSyncTime.HasValue)
{
serverTime = stats.GeoReplication.LastSyncTime.Value;
}
}
else
{
// get the server's last sync time from the container's metadata
CloudBlobContainer blobContainer = ClientRegistry.GetCloudBlobContainer(server, configuration.Name);
watch.Restart();
blobContainer.FetchAttributes();
rtt = watch.ElapsedMilliseconds;
if (blobContainer.Metadata.ContainsKey("lastsync"))
{
//if no lastmodified time is provided in the constructor, we still try to be fast.
//So, we check to see if by any chance the container previously has synchronized.
serverTime = DateTimeOffset.Parse(blobContainer.Metadata["lastsync"]);
}
}
if (serverTime.HasValue && serverTime > replicas[server].HighTime)
{
replicas[server].HighTime = serverTime.Value;
}
}
catch (StorageException)
{
// do nothing
}
}
}
}