/// <summary>
/// Returns list of parents for given node witin a snapshot
/// </summary>
/// <param name="snapshotId">Snapshot within parents are requested</param>
/// <param name="nodeId">Node which parents are returned</param>
/// <returns>List of parent node identifiers for each node in dictionary format, or null if there are no parent edges</returns>
public IEnumerator <Edge <Guid, EdgeData> > ParentEdges(Guid snapshotId, Guid nodeId)
{
lock (dataSync)
{
// Generate parents if they dont exist
if (!createdNodes)
{
createdNodes = true;
AddParentsRecursive(snapshotId, new Hashtable(), nodes);
lastSnapshotId = snapshotId;
}
// Do we have the last snapshot in the memory
if (snapshotId != lastSnapshotId)
{
// Try going for fallback provider
if (fallbackParentMapProvider != null)
{
return(fallbackParentMapProvider.ParentEdges(snapshotId, nodeId));
}
else
{
// If not, generate asked snapshot
nodes.Clear();
AddParentsRecursive(snapshotId, new Hashtable(), nodes);
lastSnapshotId = snapshotId;
}
}
// Find edge leading to holder node for given ID
if (nodes.Contains(nodeId))
{
return(BPlusTreeOperations.GetEnumerator(nodes, nodeId, EdgeType.Contains));
}
else
{
return(null);
}
}
}
/// <summary>
/// Clears nodes from the parent provider and cache
/// </summary>
public void Clear()
{
rwLock.AcquireWriterLock(-1);
try
{
parentProvider.Clear();
cacheProvider.Clear();
}
finally
{
rwLock.ReleaseLock();
}
}
/// <summary>
/// Clears nodes from the parent provider and cache
/// </summary>
public void Clear()
{
parentProvider.Clear();
cacheProvider.Clear();
}
/// <summary>
/// Clears nodes from the provider
/// </summary>
public void Clear()
{
CheckThread();
isolatedProvider.Clear();
nodeStates.Clear();
}