/// <summary>
/// Returns the implementation of the <see cref="ICloudBlobStorage"/> that corresponds to the Azure storage as defined in the specified location object.
/// </summary>
/// <param name="location">The specified location of a blob in the Azure storage infrastructure.</param>
/// <returns>The object that provides access to the Azure blob storage.</returns>
public ICloudBlobStorage GetBlobStorage(CloudBlobLocation location)
{
Guard.ArgumentNotNull(location, "location");
Guard.ArgumentNotNull(this.cloudStorageProvider, "cloudStorageProvider");
return(this.cloudStorageProvider.GetBlobStorage(location.StorageAccount));
}
private XslTransformState PersistInputDocument(Stream data)
{
CloudBlobLocation location = this.cloudStorageLoadBalancer.FindBlobLocation();
if (!CloudBlobLocation.IsUnknown(location))
{
using (ICloudBlobStorage blobStorage = this.cloudStorageLoadBalancer.GetBlobStorage(location))
{
string blobName = Guid.NewGuid().ToString("N");
if (blobStorage.Put <Stream>(location.ContainerName, blobName, data, true))
{
return(new XslTransformState(location.StorageAccount, location.ContainerName, blobName));
}
else
{
throw new InvalidOperationException(ExceptionMessages.PrepareTransformOperationFailureStreamPersistence);
}
}
}
else
{
// TODO: Auto-create missing blob container.
throw new InvalidOperationException(ExceptionMessages.FindBlobLocationFailed);
}
}
/// <summary>
/// Suggests the best location for a blob taking into account the load balancing criteria.
/// </summary>
/// <returns>The location of a blob in the Azure storage infrastructure.</returns>
public CloudBlobLocation FindBlobLocation()
{
var callToken = TraceManager.CloudStorageComponent.TraceIn();
var blobLocation = CloudBlobLocation.Unknown;
try
{
string storageAccountName = null, containerName = null;
int minBlobCount = Int32.MaxValue;
var availableAccounts = from storageAccount in this.storageAccounts.AsParallel <StorageAccountInfo>() select storageAccount;
// Enumerate through all storage accounts enabled to load balancing.
foreach (var storageAccount in availableAccounts)
{
// Access the target storage account.
using (ICloudBlobStorage blobStorage = this.cloudStorageProvider.GetBlobStorage(storageAccount.AccountName))
{
// Obtain a list of all containers in the current storage account.
var availableContainers = blobStorage.GetContainers(new ContainerRequestOptions()
{
NamePrefix = ContainerNamePrefix, ListingDetails = ContainerListingDetails.None
});
// Validate whether or not the current storage account is empty.
if (availableContainers != null)
{
// Enable parallelization when iterating through the collection of container names.
var targetContainers = from i in availableContainers.AsParallel <string>() select i;
// Enumerate through all containers enabled to load balancing.
foreach (var name in targetContainers)
{
// Obtain the minimum number of blobs in a given container.
int newMinValue = Math.Min(minBlobCount, blobStorage.GetCount(name));
// When a new minimum is found, capture its value and retain the names of the storage account and container for further reference.
if (newMinValue != minBlobCount)
{
Interlocked.Exchange <string>(ref storageAccountName, storageAccount.AccountName);
Interlocked.Exchange <string>(ref containerName, name);
Interlocked.Exchange(ref minBlobCount, newMinValue);
}
}
}
}
}
if (!String.IsNullOrEmpty(storageAccountName) && !String.IsNullOrEmpty(containerName))
{
blobLocation = new CloudBlobLocation(storageAccountName, containerName, null);
}
}
finally
{
TraceManager.CloudStorageComponent.TraceOut(callToken, blobLocation.StorageAccount, blobLocation.ContainerName);
}
return(blobLocation);
}
