/// <summary>
/// Tries to get a given <see cref="TTransfer"/> from the internal
/// cache.
/// </summary>
/// <param name="transferId">The identifier of the transfer, according to the corresponding
/// <see cref="TransferToken.TransferId"/>.</param>
/// <param name="throwExceptionIfNotFound">If true, a <see cref="UnknownTransferException"/>
/// is thrown if no matching transfer was found in the cache.</param>
/// <param name="context">The file system operation that is being performed during the invocation of
/// this method. Used for internal auditing.</param>
/// <returns>Either the matching transfer, or null, if no match was found *and*
/// <paramref name="throwExceptionIfNotFound"/> is false.</returns>
protected virtual TTransfer GetCachedTransfer(string transferId, bool throwExceptionIfNotFound, FileSystemTask context)
{
TTransfer transfer = TransferStore.TryGetTransfer(transferId);
if (transfer == null && throwExceptionIfNotFound)
{
Auditor.AuditUnknownTransferRequest(context, transferId);
string msg = String.Format("Unknown transfer ID: {0}.", transferId);
throw new UnknownTransferException(msg)
{
IsAudited = true, EventId = (int)AuditEvent.UnknownTransferRequest
};
}
return(transfer);
}