public static ReplicatedTableQuorumWriteResult TryWriteBlobQuorum <T>(List <CloudBlockBlob> blobs, T configuration, Func <string, T> ParseBlobFunc, Func <T, T, bool> ConfigIdComparer, Func <T, T> GenerateConfigId)
where T : ReplicatedTableConfigurationBase, new()
{
// Fetch all blobs ...
List <T> valuesArray;
List <string> eTagsArray;
List <ReplicatedTableReadBlobResult> resultArray = TryReadAllBlobs(blobs, out valuesArray, out eTagsArray, ParseBlobFunc);
// Find majority ...
int quorumIndex;
ReplicatedTableQuorumReadResult majority = FindMajority(resultArray, valuesArray, out quorumIndex);
string readDetails = majority.ToString();
switch (majority.Code)
{
case ReplicatedTableQuorumReadCode.NotFound:
// Create blobs ...
break;
case ReplicatedTableQuorumReadCode.UpdateInProgress:
return(new ReplicatedTableQuorumWriteResult(ReplicatedTableQuorumWriteCode.ConflictDueToUpdateInProgress, readDetails));
case ReplicatedTableQuorumReadCode.Exception:
return(new ReplicatedTableQuorumWriteResult(ReplicatedTableQuorumWriteCode.ReadExceptions, readDetails));
case ReplicatedTableQuorumReadCode.NullOrLowSuccessRate:
return(new ReplicatedTableQuorumWriteResult(ReplicatedTableQuorumWriteCode.ReadNoQuorum, readDetails));
case ReplicatedTableQuorumReadCode.Success:
// Blob has changed since ...
if (ConfigIdComparer(valuesArray[quorumIndex], configuration) == false)
{
return(new ReplicatedTableQuorumWriteResult(ReplicatedTableQuorumWriteCode.ConflictDueToBlobChange, readDetails));
}
// Update blobs ...
break;
case ReplicatedTableQuorumReadCode.BlobsNotInSyncOrTransitioning:
return(new ReplicatedTableQuorumWriteResult(ReplicatedTableQuorumWriteCode.BlobsNotInSyncOrTransitioning, readDetails));
default:
{
var msg = string.Format("Unexpected value majority=\'{0}\' ", majority.Code);
throw new Exception(msg);
}
}
// Generate a new Id for the copy of the input configuration
T newConfiguration = GenerateConfigId(configuration);
string content = newConfiguration.ToString();
// Update blobs ...
int numberOfBlobs = blobs.Count;
ReplicatedTableWriteBlobResult[] writeResultArray = new ReplicatedTableWriteBlobResult[numberOfBlobs];
Parallel.For(0, numberOfBlobs, index =>
{
T currentValue = valuesArray[index];
string currentETag = eTagsArray[index];
if (currentValue == null)
{
currentETag = null;
}
else if (!ConfigIdComparer(currentValue, configuration))
{
currentETag = "*";
}
writeResultArray[index] = TryWriteBlob(blobs[index], content, currentETag);
});
int successRate = writeResultArray.Count(e => e.Success == true);
int quorum = (numberOfBlobs / 2) + 1;
if (successRate >= quorum)
{
// Return new config Id to the caller for record
string newConfId = newConfiguration.GetConfigId().ToString();
return(new ReplicatedTableQuorumWriteResult(ReplicatedTableQuorumWriteCode.Success, newConfId, writeResultArray.ToList()));
}
return(new ReplicatedTableQuorumWriteResult(ReplicatedTableQuorumWriteCode.QuorumWriteFailure, writeResultArray.ToList()));
}
public void TurnReplicaOn(string storageAccountName, List <string> tablesToRepair, out List <ReplicatedTableRepairResult> failures)
{
if (string.IsNullOrEmpty(storageAccountName))
{
throw new ArgumentNullException("storageAccountName");
}
if (tablesToRepair == null)
{
throw new ArgumentNullException("tablesToRepair");
}
ReplicatedTableConfiguration configuration = null;
failures = new List <ReplicatedTableRepairResult>();
// - Retrieve configuration ...
ReplicatedTableQuorumReadResult readResult = RetrieveConfiguration(out configuration);
if (readResult.Code != ReplicatedTableQuorumReadCode.Success)
{
var msg = string.Format("TurnReplicaOn={0}: failed to read configuration, \n{1}", storageAccountName, readResult.ToString());
ReplicatedTableLogger.LogError(msg);
throw new Exception(msg);
}
/* - Phase 1:
* Move the *replica* to the front and set it to None.
* Make the view ReadOnly.
**/
#region Phase 1
configuration.MoveReplicaToHeadAndSetViewToReadOnly(storageAccountName);
// - Write back configuration, refresh its Id with the new one,
// but don't validate it is loaded bcz if all views of the config are empty, the config won't be refreshed by RefreshReadAndWriteViewsFromBlobs() thread!
SaveConfigAndRefreshItsIdAndValidateIsLoaded(configuration, "Phase 1", false);
#endregion
/**
* Chain is such: [None] -> [RO] -> ... -> [RO]
* or: [None] -> [None] -> ... -> [None]
**/
// - Wait for L + CF to make sure no pending transaction working on old views
Thread.Sleep(TimeSpan.FromSeconds(Constants.LeaseDurationInSec + Constants.ClockFactorInSec));
/* - Phase 2:
* Set the *replica* (head) to WriteOnly and other active replicas to ReadWrite.
* Or, in case of one replic chain
* Set only the *replica* (head) to ReadWrite.
**/
#region Phase 2
configuration.EnableWriteOnReplicas(storageAccountName);
// - Write back configuration, refresh its Id with the new one,
// and then validate it is loaded now (it has to be working since next Phase is "Repair")
SaveConfigAndRefreshItsIdAndValidateIsLoaded(configuration, "Phase 2");
#endregion
/**
* Chain is such: [W] -> [RW] -> ... -> [RW]
* or: [RW] -> [None] -> ... -> [None]
**/
// To be safe:
// - Wait for L + CF to make sure no pending transaction working on old views
Thread.Sleep(TimeSpan.FromSeconds(Constants.LeaseDurationInSec + Constants.ClockFactorInSec));
/* - Phase 3:
* Repair all tables
**/
#region Phase 3
foreach (var tableName in tablesToRepair)
{
ReplicatedTableRepairResult result = RepairTable(tableName, storageAccountName, configuration);
if (result.Code != ReplicatedTableRepairCode.Error)
{
ReplicatedTableLogger.LogInformational(result.ToString());
continue;
}
ReplicatedTableLogger.LogError(result.ToString());
// List of tables (and corresponding views) failed to repair!
failures.Add(result);
}
#endregion
/* - Phase 4:
* Set the *replica* (head) to ReadWrite.
**/
#region Phase 4
// TODO: re-evaluate if we will support this API for partitioned tables ?
configuration.EnableReadWriteOnReplicas(storageAccountName, failures.Select(r => r.ViewName).ToList());
// - Write back configuration, refresh its Id with the new one,
// and then validate it is loaded now (i.e. it is a working config)
SaveConfigAndRefreshItsIdAndValidateIsLoaded(configuration, "Phase 4");
#endregion
/**
* Chain is such: [RW] -> [RW] -> ... -> [RW] if all configured table repaired
* or: [W] -> [RW] -> ... -> [RW] if at least one configured table failed repair !
**/
}