private void RefreshBlock(ChunkDictionary block)
{
block.IsDirty = false;
// try read next chunk recently added
Reader.BaseStream.Position = block.LastChunk.ActualOffset + block.LastChunk.ActualLength;
Reader.Read();
FillBlock(block);
}
ChunkDictionary ReadBlock(long blockIndex)
{
if (blocks.TryGetValue(blockIndex - 1, out var prevBlock))
{
var prevChunkEndOffset = prevBlock.LastChunk.ActualOffset + prevBlock.LastChunk.ActualLength;
if (prevChunkEndOffset / BlockSize >= blockIndex) // previous chunk overlaps with current block
{
Reader.BaseStream.Position = prevBlock.LastChunk.ActualOffset;
}
else
{
Reader.BaseStream.Position = prevChunkEndOffset; // move to the next chunk because previous is ended in previous block
}
Reader.Read();
}
else
{
Reader.Position = blockIndex * BlockSize; // Seek & Read first chunk in block
}
ChunkDictionary block = null;
if (Reader.CurrentChunk != null)
{
block = new ChunkDictionary()
{
FirstSequenceNumber = Reader.CurrentChunk.SequenceNumber, BlockIndex = blockIndex
};
blocks.Add(blockIndex, FillBlock(block));
}
if (block != null)
{
if (Reader.EndOfStream)
{
EndingBlockIndex = block.BlockIndex;
}
else if (blockIndex > EndingBlockIndex)
{
EndingBlockIndex = -1;
}
}
return(block);
}
private ChunkDictionary FillBlock(ChunkDictionary block)
{
while (Reader.CurrentChunk != null)
{
var chunk = Reader.CurrentChunk;
if (chunk.ActualOffset / BlockSize > block.BlockIndex)
{
break;
}
block.Add(chunk.SequenceNumber, chunk);
block.LastSequenceNumber = chunk.SequenceNumber;
Reader.Read();
}
return(block);
}
