/// <summary>
/// Read an already created configuration of a CapCloudBlobContainer from the Azure's configuration blob.
/// </summary>
/// <param name="capCloudBlobContainerName">Name of the CapCloudBlobContainer</param>
/// <param name="sessionState">session state of the SLAEngine. This state is used for registering, and unregistering newly added/removed replicas</param>
/// <param name="autoRefresh">if true, it will automatically refresh the configuration by reading it periodically from the cloud storage.</param>
/// <returns></returns>
public static ContainerConfiguration ReadConfiguration(string capCloudBlobContainerName, SessionState sessionState, bool autoRefresh)
{
ContainerConfiguration result = new ContainerConfiguration(capCloudBlobContainerName, sessionState);
//reads new configuration
result.ReadConfiguration();
if (autoRefresh)
{
refreshConfigurationTask = Task.Factory.StartNew(() => result.RefreshConfigurationPeriodically());
}
if (result.PrimaryServers != null && result.PrimaryServers.Count > 0)
{
return(result);
}
else
{
return(null);
}
}
public static void RemoveConfiguration(ContainerConfiguration configuration)
{
ContainerConfigurations.Remove(configuration.Name);
}
/// <summary>
/// Read the state of the container configuration from the Azure storage.
/// </summary>
internal void ReadConfiguration()
{
ICloudBlob blob;
try
{
try
{
blob = GetConfigurationContainer().GetBlockBlobReference(ConstPool.CURRENT_CONFIGURATION_BLOB_NAME);
blob.FetchAttributes();
}
catch (StorageException se)
{
//304 is azure's not modified exception.
//it means that the configuration is not modified since last read.
if (StorageExceptionCode.NotModified(se))
{
Console.WriteLine("ReadConfiguration returned without reading...");
return;
}
//404 is Azure's not-found exception
if (StorageExceptionCode.NotFound(se))
{
Console.WriteLine("ReadConfiguration did not find a configuration blob; it needs to be created...");
PrimaryServers = null;
return;
}
Console.WriteLine(se.ToString());
Console.WriteLine(se.StackTrace);
throw se;
}
using (MemoryStream stream = new MemoryStream())
{
blob.DownloadToStream(stream);
stream.Seek(0, 0);
BinaryFormatter formatter = new BinaryFormatter();
ContainerConfiguration tmp = (ContainerConfiguration)formatter.Deserialize(stream);
if (!blob.Metadata.ContainsKey(ConstPool.EPOCH_NUMBER))
{
Console.WriteLine("No Epoch in configuration metadata!"); // this should not happen
return; // stay with current configuration for now
}
int currentEpoch = Convert.ToInt32(blob.Metadata[ConstPool.EPOCH_NUMBER]);
if (currentEpoch > Epoch)
{
PrimaryServers = tmp.PrimaryServers;
PrimaryServers.Sort();
SecondaryServers = tmp.SecondaryServers ?? new List <string>();
MainPrimaryIndex = tmp.MainPrimaryIndex;
WriteOnlyPrimaryServers = tmp.WriteOnlyPrimaryServers ?? new List <string>();
SyncPeriod = tmp.SyncPeriod;
SyncPrimaryServersWithSessionState();
SyncSecondaryServersWithSessionState();
garbageCollectOldServersFromSessionState();
Epoch = currentEpoch;
if (blob.Metadata[ConstPool.EPOCH_MODIFIED_TIME] != null)
{
EpochModifiedTime = DateTimeOffset.Parse(blob.Metadata[ConstPool.EPOCH_MODIFIED_TIME]);
}
else
{
EpochModifiedTime = DateTimeOffset.MinValue;
}
}
}
}
catch (StorageException se)
{
Console.WriteLine(se.ToString());
Console.WriteLine(se.StackTrace);
throw se;
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
Console.WriteLine(ex.StackTrace);
//throw ex;
}
}
