public static List <ReplicatedTableReadBlobResult> TryReadAllBlobs <T>(List <CloudBlockBlob> blobs, out List <T> values, out List <string> eTags, Func <string, T> ParseBlobFunc)
where T : class
{
int numberOfBlobs = blobs.Count;
T[] valuesArray = new T[numberOfBlobs];
string[] eTagsArray = new string[numberOfBlobs];
ReplicatedTableReadBlobResult[] resultArray = new ReplicatedTableReadBlobResult[numberOfBlobs];
// read from all the blobs in parallel
Parallel.For(0, numberOfBlobs, index =>
{
DateTime startTime = DateTime.UtcNow;
T currentValue;
string currentETag;
resultArray[index] = TryReadBlob(blobs[index], out currentValue, out currentETag, ParseBlobFunc);
valuesArray[index] = currentValue;
eTagsArray[index] = currentETag;
ReplicatedTableLogger.LogInformational("TryReadBlob #{0} took {1}", index, DateTime.UtcNow - startTime);
});
values = valuesArray.ToList();
eTags = eTagsArray.ToList();
return(resultArray.ToList());
}
public static ReplicatedTableQuorumReadResult TryReadBlobQuorumFast <T>(List <CloudBlockBlob> blobs, out T value, out List <string> eTags, Func <string, T> ParseBlobFunc)
where T : class
{
value = default(T);
eTags = null;
int numberOfBlobs = blobs.Count;
var valuesArray = new List <T>(new T[numberOfBlobs]);
var eTagsArray = new List <string>(new string[numberOfBlobs]);
var resultArray = new List <ReplicatedTableReadBlobResult>(new ReplicatedTableReadBlobResult[numberOfBlobs]);
var cancel = new CancellationTokenSource();
/*
* Read async all the blobs in parallel
*/
Parallel.For(0, numberOfBlobs, async(index) =>
{
valuesArray[index] = default(T);
eTagsArray[index] = null;
resultArray[index] = new ReplicatedTableReadBlobResult(ReadBlobCode.NullObject, "downloaded not started yet!");
DateTime startTime = DateTime.UtcNow;
resultArray[index] = await TryReadBlobAsync(
blobs[index],
(currentValue, currentETag) =>
{
valuesArray[index] = currentValue;
eTagsArray[index] = currentETag;
},
ParseBlobFunc,
cancel.Token);
if (resultArray[index].Code == ReadBlobCode.Success)
{
ReplicatedTableLogger.LogInformational("TryReadBlobAsync #{0} took {1}", index, DateTime.UtcNow - startTime);
}
});
/*
* Poll for "Quorum" progress ...
*/
ReplicatedTableQuorumReadResult majority;
int quorumIndex;
do
{
Thread.Sleep(Constants.QuorumPollingInMilliSeconds);
// "resultArray" may change OOB just after Evaluate Quorum step below.
// In such case, we may exit the loop because all blobs are retrieved, while "majority" has a stale value!
// Therefore, we have to determine, before Evaluate Quorum step, if we'll exit the loop or no.
// If Exist, then "majority" would be final.
// If No, then we'll loop to compute the latest, unless we break because we already have Quorum without all blobs.
bool allBlobsRetrieved = true;
// IMPORTANT: foreach()/LINQ throws when "resultArray" changes (race condition).
for (int result = 0; result < resultArray.Count; result++)
{
if (resultArray[result].Code == ReadBlobCode.NullObject)
{
allBlobsRetrieved = false;
break;
}
}
// Evaluate Quorum ...
majority = FindMajority(resultArray.AsReadOnly(), valuesArray.AsReadOnly(), out quorumIndex);
if (majority.Code == ReplicatedTableQuorumReadCode.NotFound ||
majority.Code == ReplicatedTableQuorumReadCode.UpdateInProgress ||
majority.Code == ReplicatedTableQuorumReadCode.Exception ||
majority.Code == ReplicatedTableQuorumReadCode.Success)
{
// Quorum => cancel tasks and exit
cancel.Cancel();
break;
}
//else
if (allBlobsRetrieved)
{
// All blobs 'were' retrieved => exit
break;
}
// keep polling ...
} while (true);
cancel = null;
if (majority.Code == ReplicatedTableQuorumReadCode.Success)
{
value = valuesArray[quorumIndex];
eTags = eTagsArray;
}
return(majority);
}
public void UpdateConfiguration(List <ReplicaInfo> replicaChain, int readViewHeadIndex, bool convertXStoreTableMode = false, long viewId = 0)
{
View currentView = GetWriteView();
if (viewId == 0)
{
if (!currentView.IsEmpty)
{
viewId = currentView.ViewId + 1;
}
else
{
viewId = 1;
}
}
ReplicatedTableConfigurationStore newConfig = new ReplicatedTableConfigurationStore
{
LeaseDuration = Constants.LeaseDurationInSec,
Timestamp = DateTime.UtcNow,
ReplicaChain = replicaChain,
ReadViewHeadIndex = readViewHeadIndex,
ConvertXStoreTableMode = convertXStoreTableMode,
ViewId = viewId
};
//If the read view head index is not 0, this means we are introducing 1 or more replicas at the head. For
//each such replica, update the view id in which it was added to the write view of the chain
if (readViewHeadIndex != 0)
{
for (int i = 0; i < readViewHeadIndex; i++)
{
replicaChain[i].ViewInWhichAddedToChain = viewId;
}
}
Parallel.ForEach(this.configManager.GetBlobs(), blob =>
{
ReplicatedTableConfigurationStore configurationStore = null;
string eTag;
/*
* TODO: (per Parveen Patel <*****@*****.**>)
* The below code is incomplete because we are supposed to use eTag to make the changes if the old blob exists.
* This is to support multiple clients updating the config, not a high priority scenario but something we should look at.
*/
ReplicatedTableReadBlobResult result = CloudBlobHelpers.TryReadBlob(
blob,
out configurationStore,
out eTag,
JsonStore <ReplicatedTableConfigurationStore> .Deserialize);
if (result.Code != ReadBlobCode.Success)
{
//This is the first time we are uploading the config
configurationStore = new ReplicatedTableConfigurationStore();
}
configurationStore = newConfig;
CloudBlobHelpers.TryWriteBlob(blob, configurationStore.ToJson());
});
this.configManager.Invalidate();
}
