public Task <DedupeClaim> GetLease(string messageId)
{
var now = DateTime.UtcNow;
var entity = new DedupeClaimImp
{
MessageId = messageId,
LeaseExpiration = now.Add(LeaseDuration),
Revision = 1,
Timestamp = now
};
if (Items.TryAdd(messageId, entity))
{
return(Task.FromResult <DedupeClaim>(entity));
}
var previous = entity = Items[messageId];
if (entity.IsProcessed)
{
return(Task.FromResult <DedupeClaim>(entity));
}
var isLeaseExpired = entity.LeaseExpiration < now;
if (!isLeaseExpired)
{
throw new Exception($"Lease not expired for {messageId}.");
}
entity.LeaseExpiration = now + LeaseDuration;
if (!Items.TryUpdate(messageId, entity, previous))
{
throw new Exception($"Lease for {messageId} taken by other incoming message.");
}
return(Task.FromResult <DedupeClaim>(entity));
}
public bool Equals(DedupeClaimImp other)
{
return(string.Equals(MessageId, other.MessageId) && Revision == other.Revision);
}