private async Task <LeaseResult> TryAcquireAsync(CloudBlockBlob blob, TimeSpan leaseTime, CancellationToken cancellationToken)
{
if (leaseTime < MinLeaseTime || leaseTime > MaxLeaseTime)
{
throw new ArgumentOutOfRangeException(
nameof(leaseTime),
"The lease time must be between 15 and 60 seconds, inclusive.");
}
try
{
var leaseId = await blob.AcquireLeaseAsync(
leaseTime : leaseTime,
proposedLeaseId : null,
accessCondition : null,
options : null,
operationContext : null,
cancellationToken : cancellationToken);
return(LeaseResult.Success(leaseId));
}
catch (StorageException ex) when(ex.RequestInformation?.HttpStatusCode == (int)HttpStatusCode.Conflict)
{
// The lease has already been acquired by someone else.
return(LeaseResult.Failure());
}
}
private async Task <LeaseResult> TryCreateAndAcquireAsync(CloudBlockBlob blob, TimeSpan leaseTime, CancellationToken cancellationToken)
{
try
{
// Use an empty blob for the lease blob. The contents are not important. Only the lease state (managed
// by Azure Blob Storage) is important.
await blob.UploadFromByteArrayAsync(
Array.Empty <byte>(),
index : 0,
count : 0,
cancellationToken : cancellationToken);
return(await TryAcquireAsync(blob, leaseTime, cancellationToken));
}
catch (StorageException ex) when(ex.RequestInformation?.HttpStatusCode == (int)HttpStatusCode.PreconditionFailed)
{
// The file has already created and leased by someone else.
return(LeaseResult.Failure());
}
}