/// <summary>
/// Adds a request to lock a database resource to the ordered collection.
/// </summary>
/// <param name="lockRequest">A request to lock a database resource.</param>
public void AcquireLock(LockRequest lockRequest)
{
// Insert the item in the list if it doesn't exist already. Otherwise, there is a precedence to how
// locks are allocated: a request for a write operation always replaces a request to read.
int index = this.lockRequests.BinarySearch(lockRequest);
if (index < 0)
{
this.lockRequests.Insert(~index, lockRequest);
lockRequest.AcquireLock();
}
else
{
// This will resolve the situation where the same resource has been requested more than once. A request to write
// an object will always be honered instead of a request to read.
LockRequest other = this.lockRequests[index];
if (lockRequest is RowReaderRequest && other is RowWriterRequest)
{
return;
}
// If a request to read is already in he ordered list, it will be replaced with the request to write.
if (lockRequest is RowWriterRequest && other is RowReaderRequest)
{
throw new Exception("We need a method to promote a lock here.");
}
}
}
public void Add(LockRequest lockRequest)
{
this.lockRequests.Add(lockRequest);
}
