/// <summary>
// Parse a single chunk of bytes into a single data index.
/// </summary>
/// <returns>DataIndex object containing record info.</returns>
/// <param name="bytes">The array of Bytes to parse (Must be 32 Bytes).</param>
public static BlobIndex Parse(byte[] bytes)
{
if (bytes == null)
{
throw new ArgumentNullException("byte array is required.");
}
if (bytes.Length != 32)
{
throw new ArgumentException("byte array of length 32 is required.");
}
// If the system architecture is little-endian (that is, little end first),
// reverse the byte array.
if (BitConverter.IsLittleEndian)
{
Array.Reverse(bytes);
}
// create an empty index and then set properties from loaded bytes.
var dataIndex = new BlobIndex(0, 0, 0, 0);
dataIndex.DocumentKey = BitConverter.ToInt64(bytes, 0);
dataIndex.Pointer = BitConverter.ToInt64(bytes, 8);
dataIndex.RecordLength = BitConverter.ToInt32(bytes, 16);
dataIndex.PaddingLength = BitConverter.ToInt32(bytes, 20);
// return the data index.
return(dataIndex);
}
/// <summary>
/// Updates the data index located in the data index file.
/// </summary>
/// <param name="dataIndex">The changed data index to update.</param>
public void UpdateIndex(BlobIndex dataIndex)
{
// add the index to the dataindex file.
_binaryWriter.BaseStream.Position = dataIndex.Position;
_binaryWriter.Write(dataIndex.GetBytes());
_binaryWriter.Flush();
_cache.Clear();
}
/// <summary>
/// Adds the Data Index to the Data Index file and checks for duplicate.
/// Note: The Data Index is the pointer to the record in the entites data file.
/// </summary>
/// <param name="searchKey">The Search Key (Primary Key) of the entity being stored in the data file.</param>
/// <param name="pointer">The Pointer (data position) to where the entity is being stored in the data File.</param>
/// <param name="length">The Length (number of bytes) of the data being stored in the data file.</param>
/// <exception cref="ConcurrencyException">When a data index record is found having the same Search Key</exception>
public void AddIndexCheckForDuplicate(BlobIndex dataIndex)
{
// make sure the index does not already exist if duplicate checking is enabled.
if (DoesIndexExist(dataIndex.DocumentKey))
{
throw new Exception("A Data Index record with this Search Key already exists.");
}
AddIndex(dataIndex);
}
/// <summary>
/// Adds the Data Index to the Data Index file.
/// WARNING: This function does not check for duplicates and can cause problems with duplicate Data Index's.
/// Only use AddIndex if you have some other method of making sure the Data Index's being stored are unique.
/// e.g Using an Auto incrementing Search Key (Primary Key). Using AddIndexCheckForDuplicate is slower but makes sure there is no duplicates.
/// Note: The Data Index is the pointer to the record in the entites data file.
/// </summary>
public void AddIndex(BlobIndex dataIndex)
{
// add the index to the dataindex file.
_binaryWriter.BaseStream.Position = this.FileSize;
_binaryWriter.Write(dataIndex.GetBytes());
_binaryWriter.Flush();
// advance the file size on. its better that we do it than call the length all the time as its quicker.
this.FileSize += 32;
//_cache.Clear();
}
/// <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);
}
public T Create(T entity)
{
if (entity == null)
{
throw new ArgumentNullException("Entity argument can't be null");
}
// make sure the entity name matches the document store type.
string requiredEntityName = entity.GetType().Name;
if (_entityName != requiredEntityName)
{
throw new ArgumentException("Entity type is not valid for this data store.");
}
// make sure entity has key field
if (!InternalReflectionHelper.PropertyExists(entity, "Id"))
{
throw new Exception("Entity must have an Id property and be of type short, integer or long." +
"This is used as the primary key for the entity being stored.");
}
// load the document key from the entity as its needed for adding to the index.
var documentKey = InternalReflectionHelper.GetPropertyValueInt64(entity, "Id");
// get the data store header so we can generate keys and store record counts.
var header = GetDataHeader();
// boolean so we know to check for duplicate or not on insert.
// duplicates only need checked when the user has specified the document key.
bool checkForDuplicate = true;
if (documentKey == 0)
{
checkForDuplicate = false;
}
// get the next document key from the data file header record.
documentKey = header.GenerateNextRecord(documentKey);
// update the entity value so that the callers entity gets the saved document key.
InternalReflectionHelper.SetPropertyValue(entity, "Id", documentKey);
// parse the document into a binary json document for storing in the data file.
byte[] binaryJson = _serializer.Serialize <T>(entity);
using (var _deletedDataIndexFile = new BlobIndexFile(_deletedDataIndexFilePath, DiskBufferSizes.Larger, DiskBufferSizes.Default))
{
// create the data index with the data pointer at the end of the document.
// check to see if there is a deleted slot that can be used to store the data.
var dataIndex = _deletedDataIndexFile.GetBlobIndexWithEnoughSpace(binaryJson.Length);
if (dataIndex != null)
{
// assign this document key to the deleted index.
dataIndex.ChangeDocumentKey(documentKey);
dataIndex.UpdateRecordLength(binaryJson.Length);
}
else
{
// create a new data index.
dataIndex = new BlobIndex(documentKey, this.FileSize, binaryJson.Length, this.PaddingFactor);
// update the size of the datafile
this.FileSize = this.FileSize + dataIndex.RecordLength + dataIndex.PaddingLength;
}
using (var _dataIndexFile = new BlobIndexFile(_dataIndexFilePath, DiskBufferSizes.Larger, DiskBufferSizes.Default))
{
// create the data index (AddIndex throws ConcurrencyException so no data will save)
if (checkForDuplicate)
{
_dataIndexFile.AddIndexCheckForDuplicate(dataIndex);
}
else
{
_dataIndexFile.AddIndex(dataIndex);
}
}
// remove the index from the deleted index file if it exists
_deletedDataIndexFile.RemoveIndex(dataIndex.DocumentKey);
using (var _fileStreamWriter = new FileStream(_dataFilePath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.Read,
(int)DiskBufferSizes.Default, FileOptions.SequentialScan))
{
using (var _binaryWriter = new BinaryWriter(_fileStreamWriter))
{
// add the data record to the data file
_binaryWriter.BaseStream.Position = dataIndex.Pointer;
// write the record
_binaryWriter.Write(binaryJson);
// write the padding.
if (dataIndex.PaddingLength > 0)
{
_binaryWriter.Write(new Byte[dataIndex.PaddingLength]);
}
// save the data
_binaryWriter.Flush();
}
}
// update the header record
UpdateDataHeader(header);
}
return(entity);
}
