/// <summary>
/// Removes redundant nodes (that contain only an 'End' entry).
/// </summary>
/// <param name="entryIndex">The index of the entry that may have a redundant child.</param>
/// <returns>An entry that needs to be promoted to the parent node (if any).</returns>
private IndexEntry LiftNode(int entryIndex)
{
if ((_entries[entryIndex].Flags & IndexEntryFlags.Node) != 0)
{
IndexNode childNode = _index.GetSubBlock(_entries[entryIndex]).Node;
if (childNode._entries.Count == 1)
{
long freeBlock = _entries[entryIndex].ChildrenVirtualCluster;
_entries[entryIndex].Flags = (_entries[entryIndex].Flags & ~IndexEntryFlags.Node) | (childNode._entries[0].Flags & IndexEntryFlags.Node);
_entries[entryIndex].ChildrenVirtualCluster = childNode._entries[0].ChildrenVirtualCluster;
_index.FreeBlock(freeBlock);
}
if ((_entries[entryIndex].Flags & (IndexEntryFlags.Node | IndexEntryFlags.End)) == 0)
{
IndexEntry entry = _entries[entryIndex];
_entries.RemoveAt(entryIndex);
IndexNode nextNode = _index.GetSubBlock(_entries[entryIndex]).Node;
return(nextNode.AddEntry(entry));
}
}
return(null);
}
public byte[] this[byte[] key]
{
get
{
byte[] value;
if (TryGetValue(key, out value))
{
return(value);
}
throw new KeyNotFoundException();
}
set
{
IndexEntry oldEntry;
IndexNode node;
_rootNode.TotalSpaceAvailable = _rootNode.CalcSize() +
_file.MftRecordFreeSpace(AttributeType.IndexRoot, _name);
if (_rootNode.TryFindEntry(key, out oldEntry, out node))
{
node.UpdateEntry(key, value);
}
else
{
_rootNode.AddEntry(key, value);
}
}
}
/// <summary>
/// Only valid on non-root nodes, this method divides the node in two,
/// adding the new node to the current parent.
/// </summary>
private void Divide()
{
int midEntryIdx = _entries.Count / 2;
IndexEntry midEntry = _entries[midEntryIdx];
// The terminating entry (aka end) for the new node
IndexEntry newTerm = new IndexEntry(_index.IsFileIndex);
newTerm.Flags |= IndexEntryFlags.End;
// The set of entries in the new node
List <IndexEntry> newEntries = new List <IndexEntry>(midEntryIdx + 1);
for (int i = 0; i < midEntryIdx; ++i)
{
newEntries.Add(_entries[i]);
}
newEntries.Add(newTerm);
// Copy the node pointer from the elected 'mid' entry to the new node
if ((midEntry.Flags & IndexEntryFlags.Node) != 0)
{
newTerm.ChildrenVirtualCluster = midEntry.ChildrenVirtualCluster;
newTerm.Flags |= IndexEntryFlags.Node;
}
// Set the new entries into the new node
IndexBlock newBlock = _index.AllocateBlock(_parent, midEntry);
newBlock.Node.SetEntries(newEntries, 0, newEntries.Count);
// All of the nodes that used to be referenced by an entry that's just gone
// into the new block, need to have their parent references updated to point
// to the new block.
foreach (var entry in newEntries)
{
if ((entry.Flags & IndexEntryFlags.Node) != 0)
{
IndexBlock block = _index.GetSubBlockIfCached(entry);
if (block != null)
{
block.Node._parent = newBlock.Node;
}
}
}
// Forget about the entries moved into the new node, and the entry about
// to be promoted as the new node's pointer
_entries.RemoveRange(0, midEntryIdx + 1);
// Promote the old mid entry
_parent.AddEntry(midEntry, true);
}