/// <summary>
/// Only valid on the root node, this method moves all entries into a
/// single child node.
/// </summary>
/// <returns>Whether any changes were made</returns>
internal bool Depose()
{
if (!_isRoot)
{
throw new InvalidOperationException("Only valid on root node");
}
if (_entries.Count == 1)
{
return(false);
}
IndexEntry newRootEntry = new IndexEntry(_index.IsFileIndex);
newRootEntry.Flags = IndexEntryFlags.End;
IndexBlock newBlock = _index.AllocateBlock(newRootEntry);
// Set the deposed entries into the new node. Note we updated the parent
// pointers first, because it's possible SetEntries may need to further
// divide the entries to fit into nodes. We mustn't overwrite any changes.
newBlock.Node.SetEntries(_entries, 0, _entries.Count);
_entries.Clear();
_entries.Add(newRootEntry);
return(true);
}
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);
}
internal IndexBlock GetSubBlock(IndexEntry parentEntry)
{
IndexBlock block = _blockCache[parentEntry.ChildrenVirtualCluster];
if (block == null)
{
block = new IndexBlock(this, false, parentEntry, _bpb);
_blockCache[parentEntry.ChildrenVirtualCluster] = block;
}
return(block);
}
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);
}
}
}
/// <summary>
/// Only valid on non-root nodes, this method divides the node in two,
/// adding the new node to the current parent.
/// </summary>
/// <returns>An entry that needs to be promoted to the parent node (if any)</returns>
private IndexEntry 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(midEntry);
// Set the entries into the new node. Note we updated the parent
// pointers first, because it's possible SetEntries may need to further
// divide the entries to fit into nodes. We mustn't overwrite any changes.
newBlock.Node.SetEntries(newEntries, 0, newEntries.Count);
// 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
return(midEntry);
}
internal IndexBlock AllocateBlock(IndexEntry parentEntry)
{
if (_indexStream == null)
{
_file.CreateStream(AttributeType.IndexAllocation, _name);
_indexStream = _file.OpenStream(AttributeType.IndexAllocation, _name, FileAccess.ReadWrite);
}
if (_indexBitmap == null)
{
_file.CreateStream(AttributeType.Bitmap, _name);
_indexBitmap = new Bitmap(_file.OpenStream(AttributeType.Bitmap, _name, FileAccess.ReadWrite), long.MaxValue);
}
long idx = _indexBitmap.AllocateFirstAvailable(0);
parentEntry.ChildrenVirtualCluster = idx * Utilities.Ceil(_bpb.IndexBufferSize, _bpb.SectorsPerCluster * _bpb.BytesPerSector);
parentEntry.Flags |= IndexEntryFlags.Node;
IndexBlock block = IndexBlock.Initialize(this, false, parentEntry, _bpb);
_blockCache[parentEntry.ChildrenVirtualCluster] = block;
return(block);
}
internal IndexBlock GetSubBlock(IndexEntry parentEntry)
{
IndexBlock block = _blockCache[parentEntry.ChildrenVirtualCluster];
if (block == null)
{
block = new IndexBlock(this, false, parentEntry, _bpb);
_blockCache[parentEntry.ChildrenVirtualCluster] = block;
}
return block;
}
