private void BuildIndexTable(IEnumerable <HashBlock> entries)
{
if (entries == null)
{
return;
}
foreach (HashBlock entry in entries)
{
ushort hash = RollingChecksum.HashChecksum(entry.Checksum);
if (_remoteBlocksIndexTable.ContainsKey(hash))
{
if (_remoteBlocksIndexTable[hash].Any(existingEntry => entry.Hash.SequenceEqual(existingEntry.Hash)))
{
continue;
}
_remoteBlocksIndexTable[hash].Add(entry);
}
else
{
_remoteBlocksIndexTable[hash] = new List <HashBlock>(new[] { entry });
}
}
}
public IEnumerable <IDelta> GetDeltas(Stream inputStream)
{
if (inputStream == null)
{
throw new ArgumentNullException("inputStream");
}
if (_initialized == false)
{
throw new InvalidOperationException("Initialize must be called");
}
ChecksumProvider.Reset();
var slidingBuffer = new SlidingStreamBuffer(inputStream, _blockSize);
slidingBuffer.Warmup();
bool startingNewBlock = true;
long offset = 0;
var deltas = new List <IDelta>();
var currentByteDelta = new ByteDelta();
#if DEBUG
Statistics.Matching = 0;
Statistics.PossibleMatches = 0;
Statistics.NonMatching = 0;
#endif
int currentBlockSize;
while ((currentBlockSize = (int)slidingBuffer.GetNumBytesAvailable()) > 0)
{
// Deal with signed integer limits
if (IsSignedIntLength(offset - currentByteDelta.Offset))
{
currentByteDelta.Length = (int)(offset - currentByteDelta.Offset);
deltas.Add(currentByteDelta);
startingNewBlock = true;
}
if (startingNewBlock)
{
currentByteDelta = new ByteDelta {
Offset = offset
};
ChecksumProvider.ProcessBlock(slidingBuffer.GetBuffer(), 0, currentBlockSize);
}
else if (currentBlockSize < _blockSize)
{
ChecksumProvider.TrimFront(); // remaining bytes < block_size, so read nothing new - just trim
}
else
{
ChecksumProvider.RollByte(slidingBuffer[(int)(currentBlockSize - 1)]);
}
// at this point, sigGen needs the last byte of the current block
uint currentBlockChecksum = ChecksumProvider.Value;
ushort currentBlockChecksumHash = RollingChecksum.HashChecksum(currentBlockChecksum);
if (_remoteBlocksIndexTable.ContainsKey(currentBlockChecksumHash))
{
List <HashBlock> possibleRemoteBlockMatches = _remoteBlocksIndexTable[currentBlockChecksumHash];
if (possibleRemoteBlockMatches.Any(entry => entry.Checksum == currentBlockChecksum))
{
#if DEBUG
++Statistics.PossibleMatches;
#endif
byte[] currentBlockHash = HashProvider.ComputeHash(slidingBuffer.GetBuffer(), 0,
(int)currentBlockSize);
HashBlock matchingTargetBlock;
if ((matchingTargetBlock =
possibleRemoteBlockMatches.FirstOrDefault(
entry => entry.Hash.SequenceEqual(currentBlockHash))) != null)
{
#if DEBUG
Statistics.Matching += 1;
#endif
if ((currentByteDelta.Length = (int)(offset - currentByteDelta.Offset)) > 0)
{
deltas.Add(currentByteDelta);
}
deltas.Add(new CopyDelta
{
Offset = matchingTargetBlock.Offset,
Length = matchingTargetBlock.Length
});
slidingBuffer.MoveForward((int)currentBlockSize);
offset += currentBlockSize;
startingNewBlock = true;
continue;
}
}
}
#if DEBUG
++Statistics.NonMatching;
#endif
slidingBuffer.MoveForward(1);
++offset;
startingNewBlock = false;
}
Statistics.FileLength = offset;
if (!startingNewBlock && (currentByteDelta.Length = (int)(offset - currentByteDelta.Offset)) > 0)
{
deltas.Add(currentByteDelta);
}
#if DEBUG
Statistics.FileLength = offset;
#endif
return(deltas);
}