private bool HashCheck(Block block)
{
//изчисляване на хеш стойността на блока
var hash = hasher.ComputeHash(block.Data, 0, block.Info.Length);
//сверяване на получения хеш код със този, указан в метаданните
return hash.SequenceEqual(Metadata.Checksums[block.Info.Index]);
}
private void BlockRead(bool success, Block block, object state)
{
var peer = (PeerState)state;
try
{
if (success)
{
Monitor.Read(block.Info.Length);
SendMessage(peer, new PieceMessage(block.Info.Index, block.Info.Offset, block.Data));
}
}
catch (Exception e)
{
HandleException(e);
}
}
public void AddBlock(Block block, BlockWrittenDelegate callback, object state)
{
try
{
IEnumerable<BlockPartInfo> parts = GetParts(block.Info.Index, block.Info.Offset, block.Info.Length, true);
var totalLen = parts.Sum(p => p.Length);
BlockWriteState data = writeCache.Get().Init(callback, (int)totalLen, block, state);
Trace.Assert(parts.Any());
foreach(BlockPartInfo part in parts)
{
DiskIO.QueueWrite(part.FileStream, block.Data, part.FileOffset, part.DataOffset, part.Length,
EndAddBlock, data);
}
}
catch(Exception e)
{
OnRaisedException(new TorrentException(e.Message, e));
callback(false, state);
}
}
private void PieceRead(bool success, Block block, object state)
{
if (Stopping) return;
Interlocked.Decrement(ref remainingPieces);//безопасно декрементиране на брояча
int piece = (int)state;
if (success)
{ //заключване на прочетения блок
lock(block.Data)
if(HashCheck(block))
{ //ако хеш проверката мине, блока се маркира като наличен
MarkAvailable(piece);
}
}
//ако остават 0 парчета за проверяване, процесът е завършил
//спиране и съобщение за приключване
if(remainingPieces == 0)
{
Stop(true);
OnHashingComplete();
}
}
public void GetBlock(byte[] buffer, int pieceIndex, int offset, int length, BlockReadDelegate callback, object state)
{
try
{
IEnumerable<BlockPartInfo> parts = GetParts(pieceIndex, offset, length, false);
var block = new Block(buffer, pieceIndex, offset, length);
BlockReadState data = readCache.Get().Init(block, callback, length, state);
if(parts.Count() > 1)
Trace.WriteLine(pieceIndex + " is split between " + parts.Count() + " files.");
foreach(BlockPartInfo part in parts)
{
if (part.FileStream != null)
DiskIO.QueueRead(part.FileStream, buffer, part.DataOffset, part.FileOffset, part.Length, EndGetBlock, data);
else
{
OnRaisedException(new TorrentException("Stream is null."));
callback(false, null, state);
return;
}
}
}
catch(Exception e)
{
OnRaisedException(new TorrentException(e.Message, e));
callback(false, null, state);
}
}
public BlockWriteState Init(BlockWrittenDelegate callback, int remaining, Block block, object state)
{
Callback = callback;
State = state;
Remaining = remaining;
Block = block;
return this;
}
public BlockReadState Init(Block block, BlockReadDelegate callback, int remaining, object state)
{
Block = block;
Callback = callback;
State = state;
Remaining = remaining;
return this;
}
private void WriteBlock(PieceMessage piece)
{
try
{
var block = new Block(piece.Data, piece.Index, piece.Offset, piece.Data.Length);
BlockManager.AddBlock(block, BlockWritten, block);
Interlocked.Add(ref pendingWrites, piece.Data.Length);
}
catch(Exception e)
{
HandleException(e);
}
}