/// <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 bool TryFindEntry(byte[] key, out IndexEntry entry, out IndexNode node)
{
foreach (var focus in _entries)
{
if ((focus.Flags & IndexEntryFlags.End) != 0)
{
if ((focus.Flags & IndexEntryFlags.Node) != 0)
{
IndexBlock subNode = _index.GetSubBlock(focus);
return(subNode.Node.TryFindEntry(key, out entry, out node));
}
break;
}
else
{
int compVal = _index.Compare(key, focus.KeyBuffer);
if (compVal == 0)
{
entry = focus;
node = this;
return(true);
}
else if (compVal < 0 && (focus.Flags & (IndexEntryFlags.End | IndexEntryFlags.Node)) != 0)
{
IndexBlock subNode = _index.GetSubBlock(focus);
return(subNode.Node.TryFindEntry(key, out entry, out node));
}
}
}
entry = null;
node = null;
return(false);
}
private IndexBlock(Index index, bool isRoot, long vcn, BiosParameterBlock bpb)
: base("INDX", bpb.BytesPerSector, bpb.IndexBufferSize)
{
_index = index;
_isRoot = isRoot;
_indexBlockVcn = (ulong)vcn;
_streamPosition = vcn * bpb.BytesPerSector * bpb.SectorsPerCluster;
_node = new IndexNode(WriteToDisk, UpdateSequenceSize, _index, isRoot, (uint)bpb.IndexBufferSize - FieldSize);
WriteToDisk();
}
private IEnumerable <IndexEntry> FindAllIn(IComparable <byte[]> query, IndexNode node)
{
foreach (var focus in node.Entries)
{
bool searchChildren = true;
bool matches = false;
bool keepIterating = true;
if ((focus.Flags & IndexEntryFlags.End) == 0)
{
int compVal = query.CompareTo(focus.KeyBuffer);
if (compVal == 0)
{
matches = true;
}
else if (compVal > 0)
{
searchChildren = false;
}
else if (compVal < 0)
{
keepIterating = false;
}
}
if (searchChildren && (focus.Flags & IndexEntryFlags.Node) != 0)
{
IndexBlock block = GetSubBlock(focus);
foreach (var entry in FindAllIn(query, block.Node))
{
yield return(entry);
}
}
if (matches)
{
yield return(focus);
}
if (!keepIterating)
{
yield break;
}
}
}
protected IEnumerable <IndexEntry> Enumerate(IndexNode node)
{
foreach (var focus in node.Entries)
{
if ((focus.Flags & IndexEntryFlags.Node) != 0)
{
IndexBlock block = GetSubBlock(focus);
foreach (var subEntry in Enumerate(block.Node))
{
yield return(subEntry);
}
}
if ((focus.Flags & IndexEntryFlags.End) == 0)
{
yield return(focus);
}
}
}
private void NodeAsString(TextWriter writer, string prefix, IndexNode node, string id)
{
writer.WriteLine(prefix + id + ":");
foreach (var entry in node.Entries)
{
if ((entry.Flags & IndexEntryFlags.End) != 0)
{
writer.WriteLine(prefix + " E");
}
else
{
writer.WriteLine(prefix + " " + EntryAsString(entry, _file.BestName, _name));
}
if ((entry.Flags & IndexEntryFlags.Node) != 0)
{
NodeAsString(writer, prefix + " ", GetSubBlock(entry).Node, ":i" + entry.ChildrenVirtualCluster);
}
}
}
private Index(AttributeType attrType, AttributeCollationRule collationRule, File file, string name, BiosParameterBlock bpb, UpperCase upCase)
{
_file = file;
_name = name;
_bpb = bpb;
_isFileIndex = name == "$I30";
_blockCache = new ObjectCache <long, IndexBlock>();
_file.CreateStream(AttributeType.IndexRoot, _name);
_root = new IndexRoot()
{
AttributeType = (uint)attrType,
CollationRule = collationRule,
IndexAllocationSize = (uint)bpb.IndexBufferSize,
RawClustersPerIndexRecord = bpb.RawIndexBufferSize
};
_comparer = _root.GetCollator(upCase);
_rootNode = new IndexNode(WriteRootNodeToDisk, 0, this, true, 32);
}
public bool RemoveEntry(byte[] key, out IndexEntry newParentEntry)
{
bool exactMatch;
int entryIndex = GetEntry(key, out exactMatch);
IndexEntry entry = _entries[entryIndex];
if (exactMatch)
{
if ((entry.Flags & IndexEntryFlags.Node) != 0)
{
IndexNode childNode = _index.GetSubBlock(entry).Node;
IndexEntry rLeaf = childNode.FindLargestLeaf();
byte[] newKey = rLeaf.KeyBuffer;
byte[] newData = rLeaf.DataBuffer;
IndexEntry newEntry;
childNode.RemoveEntry(newKey, out newEntry);
entry.KeyBuffer = newKey;
entry.DataBuffer = newData;
if (newEntry != null)
{
InsertEntryThisNode(newEntry);
}
newEntry = LiftNode(entryIndex);
if (newEntry != null)
{
InsertEntryThisNode(newEntry);
}
newEntry = PopulateEnd();
if (newEntry != null)
{
InsertEntryThisNode(newEntry);
}
// New entry could be larger than old, so may need
// to divide this node...
newParentEntry = EnsureNodeSize();
}
else
{
_entries.RemoveAt(entryIndex);
newParentEntry = null;
}
_store();
return(true);
}
else if ((entry.Flags & IndexEntryFlags.Node) != 0)
{
IndexNode childNode = _index.GetSubBlock(entry).Node;
IndexEntry newEntry;
if (childNode.RemoveEntry(key, out newEntry))
{
if (newEntry != null)
{
InsertEntryThisNode(newEntry);
}
newEntry = LiftNode(entryIndex);
if (newEntry != null)
{
InsertEntryThisNode(newEntry);
}
newEntry = PopulateEnd();
if (newEntry != null)
{
InsertEntryThisNode(newEntry);
}
// New entry could be larger than old, so may need
// to divide this node...
newParentEntry = EnsureNodeSize();
_store();
return(true);
}
}
newParentEntry = null;
return(false);
}