protected override void Write(IFileWriter dataWriter, DataChunk chunk)
{
var prefixSize = StructSerializer.GetSize <GzipChunkPrefix>();
using (MemoryStream memoryStream = new MemoryStream(prefixSize + chunk.Data.Length))
{
using (GZipStream compressionStream = new GZipStream(memoryStream, CompressionMode.Compress, leaveOpen: true))
{
memoryStream.Position = prefixSize;
compressionStream.Write(chunk.Data, 0, chunk.Data.Length);
}
var prefix = new GzipChunkPrefix()
{
ChunkSize = chunk.Data.Length,
Offset = chunk.Offset,
GzipDataSize = (int)memoryStream.Length - prefixSize
};
memoryStream.Position = 0;
var prefixBytes = StructSerializer.Serialize(prefix);
memoryStream.Write(prefixBytes, 0, prefixBytes.Length);
memoryStream.Capacity = (int)memoryStream.Length;
var compressedData = memoryStream.GetBuffer();
var offset = Interlocked.Add(ref _writeOffset, compressedData.Length) - compressedData.Length;
dataWriter.WriteChunk(offset, compressedData);
}
}
protected override DataChunk Read(IFileReader dataReader)
{
long offset;
GzipChunkPrefix prefix;
DataChunk dataChunk = null;
lock (_locker)
{
if (_readOffset >= dataReader.Size)
{
return(null);
}
var prefixSize = StructSerializer.GetSize <GzipChunkPrefix>();
var prefixBytes = dataReader.ReadChunk(_readOffset, prefixSize);
prefix = StructSerializer.Deserialize <GzipChunkPrefix>(prefixBytes);
offset = _readOffset + prefixSize;
_readOffset = offset + prefix.GzipDataSize;
}
var decompressedData = new byte[prefix.ChunkSize];
var data = dataReader.ReadChunk(offset, prefix.GzipDataSize);
using (MemoryStream memoryStream = new MemoryStream(data))
{
using (GZipStream decompressionStream = new GZipStream(memoryStream, CompressionMode.Decompress, leaveOpen: true))
{
var decompressedDataSize = decompressionStream.Read(decompressedData, 0, prefix.ChunkSize);
if (decompressedDataSize != prefix.ChunkSize)
{
Console.WriteLine("The specified compressed file is malformed.");
}
}
dataChunk = new DataChunk(prefix.Offset, decompressedData);
}
return(dataChunk);
}
