public ArraySegment <byte> GetBlock(Hash hash)
{
// Cache
{
var result = _blocksManager.Get(hash);
if (result != null)
{
return(result.Value);
}
}
// Share
{
ArraySegment <byte>?result = null;
string path = null;
lock (_lockObject)
{
var shareInfo = _contentInfoManager.GetShareInfo(hash);
if (shareInfo != null)
{
var buffer = _bufferManager.TakeBuffer(shareInfo.BlockLength);
try
{
int length;
try
{
using (var stream = new UnbufferedFileStream(shareInfo.Path, FileMode.Open, FileAccess.Read, FileShare.Read, FileOptions.None, _bufferManager))
{
stream.Seek((long)shareInfo.GetIndex(hash) * shareInfo.BlockLength, SeekOrigin.Begin);
length = (int)Math.Min(stream.Length - stream.Position, shareInfo.BlockLength);
stream.Read(buffer, 0, length);
}
}
catch (ArgumentOutOfRangeException)
{
throw new BlockNotFoundException();
}
catch (IOException)
{
throw new BlockNotFoundException();
}
result = new ArraySegment <byte>(buffer, 0, length);
path = shareInfo.Path;
}
catch (Exception)
{
_bufferManager.ReturnBuffer(buffer);
throw;
}
}
}
if (result != null)
{
if (hash.Algorithm == HashAlgorithm.Sha256 &&
Unsafe.Equals(Sha256.Compute(result.Value), hash.Value))
{
return(result.Value);
}
else
{
_bufferManager.ReturnBuffer(result.Value.Array);
result = null;
this.RemoveContent(path);
}
}
}
throw new BlockNotFoundException();
}