/// <summary>
/// Reads and collects clusters in index
/// </summary>
private void ReconstructIndex()
{
byte[] buffer = new byte[HeaderCluster.HeaderBytes];
for (int i = 0; i < (fs.Length - ReservedHeaderLength) / clusterSize; i++)
{
PositionToCluster(i);
fs.Read(buffer, 0, buffer.Length);
ClusterFlags flags = (ClusterFlags)buffer[0];
if (flags != ClusterFlags.Empty)
{
if ((flags & ClusterFlags.StreamHeader) != 0)
{
Guid id = new Guid(new byte[] { buffer[5], buffer[6], buffer[7], buffer[8], buffer[9], buffer[10], buffer[11], buffer[12], buffer[13], buffer[14], buffer[15], buffer[16], buffer[17], buffer[18], buffer[19], buffer[20] });
if (!id.Equals(indexKey))
{
if ((flags & ClusterFlags.SafeCopy) != 0)
{
// Write not safe copy status
PositionToCluster(i);
fs.WriteByte((byte)ClusterFlags.StreamHeader);
// Key already in index ?
if (index.ContainsKey(id))
{
// Delete previous chain and free space
DeleteChain((int)index[id], true);
// Remove from index
index.Remove(id);
}
}
if (!index.ContainsKey(id))
{
index.Add(id, i);
}
else
{
// Delete duplicate chain and free space
DeleteChain(i, true);
}
}
else
{
// Index entry found at this point means it was corrupted
DeleteChain(i, false);
}
}
}
else
{
#if DEBUG
Debug.Assert(!emptyClusters.Contains(i));
#endif
emptyClusters.Enqueue(i);
}
}
}
/// <summary>
/// Reads the data from file
/// </summary>
/// <param name="clusterNumber">Cluster of data location.</param>
/// <returns>Data bytes</returns>
private byte[] Read(int clusterNumber)
{
byte[] result = null;
int dataOffset = 0;
int dataLength = 1;
byte[] buffer = new byte[clusterSize];
while (dataOffset < dataLength)
{
PositionToCluster(clusterNumber);
fs.Read(buffer, 0, clusterSize);
ClusterFlags flags = (ClusterFlags)buffer[0];
int headerBytes = 0;
if ((flags & ClusterFlags.StreamHeader) != 0)
{
clusterNumber = BitConverter.ToInt32(buffer, 1);
dataLength = BitConverter.ToInt32(buffer, 21);
headerBytes = HeaderCluster.HeaderBytes;
if (result == null)
{
result = new byte[dataLength];
}
else
{
throw new InvalidOperationException("Unexpected second header in chain");
}
}
else
{
if ((flags & ClusterFlags.StreamData) != 0)
{
clusterNumber = BitConverter.ToInt32(buffer, 1);
headerBytes = DataCluster.HeaderBytes;
}
else
{
throw new InvalidDataException();
}
}
if (result == null)
{
throw new InvalidOperationException("Header not found in chain");
}
int remainingBytes = clusterSize - headerBytes;
Array.Copy(buffer, headerBytes, result, dataOffset, Math.Min(remainingBytes, dataLength - dataOffset));
dataOffset += remainingBytes;
}
return(result);
}
/// <summary>
/// Reads the chain of clusters
/// </summary>
/// <param name="clusterNumber">Cluster number</param>
/// <returns>Cluster chain</returns>
private DataCluster ReadChain(int clusterNumber)
{
if (clusterNumber == -1)
{
return(null);
}
// Position to start of cluster
PositionToCluster(clusterNumber);
byte[] buffer = new byte[HeaderCluster.HeaderBytes];
fs.Read(buffer, 0, buffer.Length);
ClusterFlags flags = (ClusterFlags)buffer[0];
if ((flags & ClusterFlags.StreamHeader) != 0)
{
HeaderCluster cluster = new HeaderCluster(
flags,
new Guid(new byte[] { buffer[5], buffer[6], buffer[7], buffer[8], buffer[9], buffer[10], buffer[11], buffer[12], buffer[13], buffer[14], buffer[15], buffer[16], buffer[17], buffer[18], buffer[19], buffer[20] }),
clusterNumber,
BitConverter.ToInt32(buffer, 21),
ReadChain(BitConverter.ToInt32(buffer, 1))
);
return(cluster);
}
else
{
if ((flags & ClusterFlags.StreamData) != 0)
{
DataCluster cluster = new DataCluster(
flags,
clusterNumber,
ReadChain(BitConverter.ToInt32(buffer, 1)));
return(cluster);
}
else
{
return(null);
}
}
}
/// <summary>
/// Generates report about data fragmentation
/// </summary>
/// <returns>List of present bytestream lengths separated by newline</returns>
public string FragmentationReport()
{
StringBuilder sb = new StringBuilder();
byte[] buffer = new byte[clusterSize];
foreach (Guid item in index.Keys)
{
int clusterNumber = (int)index[item];
PositionToCluster(clusterNumber);
fs.Read(buffer, 0, clusterSize);
ClusterFlags flags = (ClusterFlags)buffer[0];
if ((flags & ClusterFlags.StreamHeader) != 0)
{
int dataLength = BitConverter.ToInt32(buffer, 21);
sb.AppendLine(dataLength.ToString());
}
}
return(sb.ToString());
}
/// <summary>
/// Creates new instance of HeaderCluster type
/// </summary>
/// <param name="flags">Initial flags</param>
/// <param name="clusterNumber">Assigned cluster number</param>
/// <param name="nextCluster">Next cluster</param>
/// <param name="key">Key which is stored</param>
/// <param name="dataLength">Total data length</param>
public HeaderCluster(ClusterFlags flags, Guid key, int clusterNumber, int dataLength, DataCluster nextCluster)
: base(flags, clusterNumber, nextCluster)
{
this.Key = key;
this.DataLength = dataLength;
}
/// <summary>
/// Creates new instance of DataCluster type
/// </summary>
/// <param name="flags">Initial flags</param>
/// <param name="clusterNumber">Assigned cluster number</param>
/// <param name="nextCluster">Next cluster</param>
public DataCluster(ClusterFlags flags, int clusterNumber, DataCluster nextCluster)
{
this.Flags = flags;
this.ClusterNumber = clusterNumber;
this.NextCluster = nextCluster;
}
/// <summary>
/// Creates new instance of DataCluster type
/// </summary>
/// <param name="flags">Initial flags</param>
/// <param name="clusterNumber">Assigned cluster number</param>
/// <param name="nextCluster">Next cluster</param>
public DataCluster(ClusterFlags flags, int clusterNumber, DataCluster nextCluster)
{
this.Flags = flags;
this.ClusterNumber = clusterNumber;
this.NextCluster = nextCluster;
}
/// <summary>
/// Creates new instance of HeaderCluster type
/// </summary>
/// <param name="flags">Initial flags</param>
/// <param name="clusterNumber">Assigned cluster number</param>
/// <param name="nextCluster">Next cluster</param>
/// <param name="key">Key which is stored</param>
/// <param name="dataLength">Total data length</param>
public HeaderCluster(ClusterFlags flags, Guid key, int clusterNumber, int dataLength, DataCluster nextCluster) :
base(flags, clusterNumber, nextCluster)
{
this.Key = key;
this.DataLength = dataLength;
}