private static HeadCandidate SelectHead(Database db, BlocksTemp blocks, HeadSelector selector)
{
var heads = blocks.Blocks.Where(block => !block.HasChildren).ToList();
if (heads.Count == 0)
{
throw new Exception("Invalid blockchain. Circular topologies are invalid.");
}
if (heads.Count == 1)
{
return(heads[0]);
}
var hash = db.BlockchainHead;
if (hash == null)
{
if (selector == null)
{
throw new Exception("Can't read blockchain head from DB.");
}
hash = selector(heads).Hash;
}
HeadCandidate ret;
if (!blocks.BlockMap.TryGetValue(hash, out ret))
{
throw new Exception(
$"DB states that the blockchain head is {hash}, but no such block exists in the DB.");
}
return(ret);
}
private static BlocksTemp BuildBlocks(Database db)
{
var ret = new BlocksTemp();
foreach (var block in db.GetAllBlocks())
{
var candidate = new HeadCandidate
{
DbId = block.Id,
Hash = block.Hash,
PreviousHash = block.PreviousHash
};
ret.Blocks.Add(candidate);
ret.BlockMap[block.Hash] = candidate;
}
foreach (var block in ret.Blocks)
{
HeadCandidate previous;
if (!ret.BlockMap.TryGetValue(block.PreviousHash, out previous))
{
continue;
}
block.Previous = previous;
block.Previous.HasChildren = true;
}
return(ret);
}
