private void LoadChildren()
{
//test if we already have everything in cache?
if (children != null)
{
return;
}
//create empty cache
children = new Dictionary <string, VirtualNode>();
//read this dir's data sector
DATA_SECTOR dataSector = DATA_SECTOR.CreateFromBytes(drive.Disk.ReadSector(DataSectorAt));
//create virtual nodes for each child and add to children dictionary
byte[] data = dataSector.DataBytes;
for (int i = 0; i < ChildCount; i++)
{
int childAt = BitConverter.ToInt32(data, i * 4);
NODE childNodeSector = NODE.CreateFromBytes(drive.Disk.ReadSector(childAt));
VirtualNode childNode = new VirtualNode(drive, childAt, childNodeSector, this);
children.Add(childNode.Name, childNode);
}
}
private List <VirtualBlock> blocks; // cache of file blocks
public VirtualNode(VirtualDrive drive, int nodeSector, NODE sector, VirtualNode parent)
{
this.drive = drive;
this.nodeSector = nodeSector;
this.sector = sector;
this.parent = parent;
this.children = null; // initially empty cache
this.blocks = null; // initially empty cache
}
private VirtualNode CreateNode(string name, SECTOR.SectorType type)
{
// Create a new file, both on disk and in memory
// type may be DIR_NODE or FILE_NODE
if (type != SECTOR.SectorType.DIR_NODE && type != SECTOR.SectorType.FILE_NODE)
{
throw new Exception("Illegal type, CreateNode only take DIR_NODE and FILE_NODE types!");
}
// Get 2 free sectors
// First Sector: NODE, containing metadata
// Second Sector: DATA_SECTOR, containing the new node's data
int[] freeSectors = drive.GetNextFreeSectors(2);
if (freeSectors == null || freeSectors.Length != 2)
{
throw new Exception("Can't find 2 free sectors for a new " +
(type == SECTOR.SectorType.DIR_NODE ? "directory" : "file") + "!");
}
int newNodeAt = freeSectors[0];
int newDataSectorAt = freeSectors[1];
// Create the node sector on disk, initially empty
int bps = drive.Disk.BytesPerSector;
NODE newNode = (type == SECTOR.SectorType.DIR_NODE
? new DIR_NODE(bps, newDataSectorAt, name, 0) as NODE
: new FILE_NODE(bps, newDataSectorAt, name, 0) as NODE);
//Create the DATA_SECTOR sector on disk for the new directory
// initially empty data sector for this new directory
DATA_SECTOR dataSector = new DATA_SECTOR(bps, 0, null);
// Write sectors to disk
drive.Disk.WriteSector(newNodeAt, newNode.RawBytes);
drive.Disk.WriteSector(newDataSectorAt, dataSector.RawBytes);
// Create a new VirtualNode instance
VirtualNode newVirtualNode = new VirtualNode(drive, newNodeAt, newNode, this);
// Add this to the in-memory cache of this directory's children
LoadChildren();
children.Add(name, newVirtualNode);
CommitChildren();
// Return the new VirtualNode instace
return(newVirtualNode);
}
private void LoadChildren()
{
if (children == null)
{
children = new Dictionary <string, VirtualNode>();
DATA_SECTOR data = DATA_SECTOR.CreateFromBytes(drive.Disk.ReadSector(sector.FirstDataAt));
for (int i = 0; i < ChildCount; i++)
{
int childAddress = BitConverter.ToInt32(data.DataBytes, i * 4);
NODE childSector = NODE.CreateFromBytes(drive.Disk.ReadSector(childAddress));
VirtualNode vn = new VirtualNode(drive, childAddress, childSector, this);
children.Add(childSector.Name, vn);
}
}
}