public AppLeaseManager(
AzureStorageClient azureStorageClient,
IPartitionManager partitionManager,
string appLeaseContainerName,
string appLeaseInfoBlobName,
AppLeaseOptions options)
{
this.azureStorageClient = azureStorageClient;
this.partitionManager = partitionManager;
this.appLeaseContainerName = appLeaseContainerName;
this.appLeaseInfoBlobName = appLeaseInfoBlobName;
this.options = options;
this.storageAccountName = this.azureStorageClient.BlobAccountName;
this.settings = this.azureStorageClient.Settings;
this.taskHub = settings.TaskHubName;
this.workerName = settings.WorkerId;
this.appName = settings.AppName;
this.appLeaseIsEnabled = this.settings.UseAppLease;
this.appLeaseContainer = this.azureStorageClient.GetBlobContainerReference(this.appLeaseContainerName);
this.appLeaseInfoBlob = this.appLeaseContainer.GetBlobReference(this.appLeaseInfoBlobName);
var appNameHashInBytes = BitConverter.GetBytes(Fnv1aHashHelper.ComputeHash(this.appName));
Array.Resize(ref appNameHashInBytes, 16);
this.appLeaseId = new Guid(appNameHashInBytes).ToString();
this.isLeaseOwner = false;
this.shutdownCompletedEvent = new AsyncManualResetEvent();
}
public static string GetForwardFrontEnd(string runtimeSiteName, HttpScaleEnvironment environment)
{
if (environment.DynamicComputeHttpScaleMaxFrontEndsPerSite <= 0)
{
throw new ArgumentOutOfRangeException("DynamicComputeHttpScaleMaxFrontEndsPerSite must be greater than 0");
}
// each FE handles scale independently
if (environment.DynamicComputeHttpScaleMaxFrontEndsPerSite > 2)
{
return(environment.CurrentFrontEnd);
}
// this is degenerated case where no FE is alive, all FE should handle
var frontEnds = environment.FrontEnds;
if (frontEnds.Count == 0)
{
return(environment.CurrentFrontEnd);
}
// if only one FE is alive, it should handle
if (frontEnds.Count == 1)
{
return(frontEnds[0]);
}
var currentBucket = (int)(Fnv1aHashHelper.ComputeHash(runtimeSiteName) % frontEnds.Count);
// if only forward to 1 frontend
if (environment.DynamicComputeHttpScaleMaxFrontEndsPerSite == 1)
{
return(frontEnds[currentBucket]);
}
// forwarding to 2 frontends at most
var forwardFrontEnds = new List <string>(2);
forwardFrontEnds.Add(frontEnds[currentBucket]);
forwardFrontEnds.Add(frontEnds[(currentBucket + 1) % frontEnds.Count]);
if (forwardFrontEnds.Any(n => n == environment.CurrentFrontEnd))
{
return(environment.CurrentFrontEnd);
}
var random = new Random();
return(forwardFrontEnds[random.Next() % forwardFrontEnds.Count]);
}
