public void Add(string key, IndexData indexData)
{
if (Contains(key))
{
throw new DuplicateException(nameof(key));
}
NewNode(key, indexData);
}
//generates new node on the stream and adds this into rootNode.
private void NewNode(string key, IndexData indexData)
{
if (string.IsNullOrEmpty(key))
{
throw new ArgumentNullException(nameof(key));
}
if (indexData == null)
{
throw new ArgumentNullException(nameof(indexData));
}
CheckDisposed();
var keyBuffer = Encoding.UTF8.GetBytes(key);
var newNodeSize = DefaultSizes.DefaultNodeSize + keyBuffer.Length;
EnsureCapacity(_indexCursor, newNodeSize);
using (var writer = _indexFile.CreateViewStream(_indexCursor, newNodeSize, MemoryMappedFileAccess.Write))
{
var keyOffset = _indexCursor + DefaultSizes.DefaultNodeSize;
writer.WriteLong(keyOffset); // keyOffset
writer.WriteInt(keyBuffer.Length); //keySize
WriteIndexData(writer, indexData); //indexData
writer.Write(keyBuffer, 0, keyBuffer.Length); //key itself
_indexCursor += writer.Position;
var keyInfo = new KeyInfo
{
Key = key,
Offset = keyOffset,
Size = keyBuffer.Length
};
var node = new Node()
{
KeyInfo = keyInfo,
IndexData = indexData,
};
//since we have to check if key exist before add new node, this approach accelerate check speed
_rootNode.Nodes.Add(key, node);
}
Commit();
}
private IndexData ReadIndexData(KeyInfo keyInfo)
{
var offset = keyInfo.Offset - DefaultSizes.IndexDataSize; // Index data is stored before key
using (var reader = _indexFile.CreateViewStream(offset, DefaultSizes.IndexDataSize, MemoryMappedFileAccess.Read))
{
var indexData = new IndexData
{
Md5Hash = new byte[DefaultSizes.Md5HashSize],
Size = reader.ReadLong(),
Offset = reader.ReadLong()
};
reader.Read(indexData.Md5Hash, 0, DefaultSizes.Md5HashSize);
return(indexData);
}
}
public void Add(string key, IndexData indexData)
{
WriteLock(() => _index.Add(key, indexData), $"Timeout {_timeout} expired to add key {key} to index");
}
private static void WriteIndexData(Stream writer, IndexData data)
{
writer.WriteLong(data.Size);
writer.WriteLong(data.Offset);
writer.Write(data.Md5Hash, 0, DefaultSizes.Md5HashSize);
}
