/// <summary>
/// Gets the data index for record.
/// Returns null when at the end of the data index file.
/// </summary>
/// <returns>The index for record.</returns>
/// <param name="recdordNumber">Record number.</param>
public BlobIndex GetBlobIndex(long dataIndexNumber)
{
long positionOfIndex = (dataIndexNumber - 1) * 32;
_binaryReader.BaseStream.Position = positionOfIndex;
if (this.FileSize > positionOfIndex)
{
byte[] dataIndexBytes = _binaryReader.ReadBytes(32);
var dataIndex = BlobIndex.Parse(dataIndexBytes);
if (dataIndex.DocumentKey > 0)
{
dataIndex.Position = positionOfIndex;
return(dataIndex);
}
}
return(null);
}
/// <summary>
/// Gets the first available data index with space greater than the size specified in bytes.
/// The index returned is the size greater than the length with the combined record length and padding bytes.
/// </summary>
/// <returns>The data index with space greater than length specified.</returns>
/// <param name="dataLength">Data length in bytes.</param>
public BlobIndex GetBlobIndexWithEnoughSpace(long dataLength)
{
long positionOfIndex = 0;
_binaryReader.BaseStream.Position = positionOfIndex;
// search the index cache before going to disk.
foreach (var dataIndex in _cache)
{
if (dataIndex.RecordLength + dataIndex.PaddingLength > dataLength && dataIndex.DocumentKey != 0)
{
return(dataIndex);
}
}
// position of where to continue the search from on disk.
if (_cache.Count() > 0)
{
positionOfIndex = (_cache.Count() - 1) * 32;
}
// loop through the index until search key is found.
_binaryReader.BaseStream.Position = positionOfIndex;
while (_binaryReader.BaseStream.Position < this.FileSize)
{
// load the bytes, convert to index object and return
byte[] dataIndexBytes = _binaryReader.ReadBytes(32);
var dataIndex = BlobIndex.Parse(dataIndexBytes);
// add the index to the read cache so next search is quicker.
_cache.Add(dataIndex);
// return the index if there is more space than specified.
if (dataIndex.RecordLength + dataIndex.PaddingLength >= dataLength && dataIndex.DocumentKey != 0)
{
return(dataIndex);
}
}
return(null);
}
/// <summary>
/// Adds an index to the Data Index file.
/// Overwrites the first data index found with a 0 for its document key.
/// </summary>
public void AddIndexOverwriteDeleted(BlobIndex dataIndex)
{
// add the index to the dataindex file.
_binaryReader.BaseStream.Position = 0;
while (_binaryReader.BaseStream.Position < this.FileSize)
{
// load the bytes, convert to index object and return
byte[] dataIndexBytes = _binaryReader.ReadBytes(32);
var existingBlobIndex = BlobIndex.Parse(dataIndexBytes);
// check if null
if (existingBlobIndex.DocumentKey == 0)
{
_binaryWriter.BaseStream.Position = _binaryReader.BaseStream.Position;
_binaryWriter.Write(dataIndex.GetBytes());
_binaryWriter.Flush();
return;
}
}
// not found so add to end.
AddIndex(dataIndex);
}
/// <summary>
/// Finds the Data Index in the file with the given Search Key (Primary Key).
/// </summary>
/// <returns>The Data Index containing the data record info.</returns>
/// <param name="searchKey">The Document Key (Primary Key) of the entity to find.</param>
public BlobIndex FindIndex(long documentKey)
{
if (documentKey == 0)
{
return(null);
}
// attempt to find the key by calculation first (Only for Autoincremented document collections).
// if cant find then search the full index file.
long positionOfIndex = (documentKey - 1) * 32;
_binaryReader.BaseStream.Position = positionOfIndex;
// dont attempt to load bytes when the document key is at the end of the file
if (this.FileSize > positionOfIndex)
{
byte[] dataIndexBytes = _binaryReader.ReadBytes(32);
var dataIndexInitial = BlobIndex.Parse(dataIndexBytes);
if (dataIndexInitial.DocumentKey == documentKey)
{
dataIndexInitial.Position = positionOfIndex;
return(dataIndexInitial);
}
}
// search the index cache before going to disk.
var fromCache = _cache.SingleOrDefault(key => key.DocumentKey == documentKey && key.DocumentKey > 0);
if (fromCache != null)
{
return(fromCache);
}
// position of where to continue the search from on disk.
if (_cache.Count() > 0)
{
positionOfIndex = (_cache.Count() - 1) * 32;
}
else
{
positionOfIndex = 0;
}
// loop through the index until search key is found.
_binaryReader.BaseStream.Position = positionOfIndex;
while (_binaryReader.BaseStream.Position < this.FileSize)
{
// load the bytes, convert to index object and return
byte[] dataIndexBytes = _binaryReader.ReadBytes(32);
var dataIndex = BlobIndex.Parse(dataIndexBytes);
// add the index to the read cache so next search is quicker.
_cache.Add(dataIndex);
// if the document key matches return it.
if (dataIndex.DocumentKey == documentKey)
{
dataIndex.Position = positionOfIndex;
return(dataIndex);
}
}
// the data index was not found in the data index file.
return(null);
}
