public BlockDemand(BlockHeader header, BoundPeer peer, DateTimeOffset timestamp)
{
Header = header;
Peer = peer;
Timestamp = timestamp;
}
public PeerChainState(BoundPeer peer, long tipIndex, BigInteger totalDifficulty)
{
Peer = peer;
TipIndex = tipIndex;
TotalDifficulty = totalDifficulty;
}
#pragma warning disable MEN003
private async Task <BlockChain <T> > FillBlocksAsync(
BoundPeer peer,
BlockChain <T> blockChain,
BlockHash?stop,
IProgress <BlockDownloadState> progress,
long totalBlockCount,
long receivedBlockCount,
bool evaluateActions,
TimeSpan timeout,
int logSessionId,
CancellationToken cancellationToken
)
{
var sessionRandom = new Random();
const string fname = nameof(FillBlocksAsync);
BlockChain <T> workspace = blockChain;
var scope = new List <Guid>();
bool renderActions = evaluateActions;
bool renderBlocks = true;
try
{
while (!cancellationToken.IsCancellationRequested)
{
int subSessionId = sessionRandom.Next();
Block <T> tip = workspace?.Tip;
_logger.Debug(
"{SessionId}/{SubSessionId}: Trying to find branchpoint...",
logSessionId,
subSessionId
);
BlockLocator locator = workspace.GetBlockLocator();
_logger.Debug(
"{SessionId}/{SubSessionId}: Locator's length: {LocatorLength}",
logSessionId,
subSessionId,
locator.Count()
);
IAsyncEnumerable <Tuple <long, BlockHash> > hashesAsync = GetBlockHashes(
peer: peer,
locator: locator,
stop: stop,
timeout: timeout,
logSessionIds: (logSessionId, subSessionId),
cancellationToken: cancellationToken
);
IEnumerable <Tuple <long, BlockHash> > hashes = await hashesAsync.ToArrayAsync();
if (!hashes.Any())
{
_logger.Debug(
"{SessionId}/{SubSessionId}: Peer {0} returned no hashes; ignored.",
logSessionId,
subSessionId,
peer.Address.ToHex()
);
return(workspace);
}
hashes.First().Deconstruct(
out long branchIndex,
out BlockHash branchpoint
);
_logger.Debug(
"{SessionId}/{SubSessionId}: Branchpoint is #{BranchIndex} {BranchHash}.",
logSessionId,
subSessionId,
branchIndex,
branchpoint
);
if (tip is null || branchpoint.Equals(tip.Hash))
{
_logger.Debug(
"{SessionId}/{SubSessionId}: It doesn't need to fork.",
logSessionId,
subSessionId
);
}
else if (!workspace.ContainsBlock(branchpoint))
{
// FIXME: This behavior can unexpectedly terminate the swarm (and the game
// app) if it encounters a peer having a different blockchain, and therefore
// can be exploited to remotely shut down other nodes as well.
// Since the intention of this behavior is to prevent mistakes to try to
// connect incorrect seeds (by a user), this behavior should be limited for
// only seed peers.
var msg =
$"Since the genesis block is fixed to {BlockChain.Genesis} " +
"protocol-wise, the blockchain which does not share " +
"any mutual block is not acceptable.";
throw new InvalidGenesisBlockException(
branchpoint,
workspace.Genesis.Hash,
msg);
}
else
{
_logger.Debug(
"{SessionId}/{SubSessionId}: Needs to fork; trying to fork...",
logSessionId,
subSessionId
);
workspace = workspace.Fork(branchpoint);
Guid workChainId = workspace.Id;
scope.Add(workChainId);
renderActions = false;
renderBlocks = false;
_logger.Debug(
"{SessionId}/{SubSessionId}: Fork finished.",
logSessionId,
subSessionId
);
}
if (!(workspace.Tip is null))
{
hashes = hashes.Skip(1);
}
_logger.Debug(
"{SessionId}/{SubSessionId}: Trying to fill up previous blocks...",
logSessionId,
subSessionId
);
var hashesAsArray = hashes as Tuple <long, BlockHash>[] ?? hashes.ToArray();
if (!hashesAsArray.Any())
{
break;
}
int hashCount = hashesAsArray.Count();
_logger.Debug(
"{SessionId}/{SubSessionId}: Required {Hashes} hashes " +
"(tip: #{TipIndex} {TipHash}).",
logSessionId,
subSessionId,
hashCount,
workspace.Tip?.Index,
workspace.Tip?.Hash
);
totalBlockCount = Math.Max(totalBlockCount, receivedBlockCount + hashCount);
IAsyncEnumerable <Block <T> > blocks = GetBlocksAsync(
peer,
hashesAsArray.Select(pair => pair.Item2),
cancellationToken
);
var receivedBlockCountCurrentLoop = 0;
await foreach (Block <T> block in blocks)
{
const string startMsg =
"{SessionId}/{SubSessionId}: Try to append a block " +
"#{BlockIndex} {BlockHash}...";
_logger.Debug(
startMsg,
logSessionId,
subSessionId,
block.Index,
block.Hash
);
cancellationToken.ThrowIfCancellationRequested();
workspace.Append(
block,
DateTimeOffset.UtcNow,
evaluateActions: evaluateActions,
renderBlocks: renderBlocks,
renderActions: renderActions
);
receivedBlockCountCurrentLoop++;
progress?.Report(new BlockDownloadState
{
TotalBlockCount = totalBlockCount,
ReceivedBlockCount = receivedBlockCount + receivedBlockCountCurrentLoop,
ReceivedBlockHash = block.Hash,
SourcePeer = peer,
});
const string endMsg =
"{SessionId}/{SubSessionId}: Block #{BlockIndex} {BlockHash} " +
"was appended.";
_logger.Debug(endMsg, logSessionId, subSessionId, block.Index, block.Hash);
}
receivedBlockCount += receivedBlockCountCurrentLoop;
var isEndedFirstTime = receivedBlockCount == receivedBlockCountCurrentLoop &&
receivedBlockCount < FindNextHashesChunkSize - 1;
if (receivedBlockCountCurrentLoop < FindNextHashesChunkSize && isEndedFirstTime)
{
_logger.Debug(
"{SessionId}/{SubSessionId}: Got {Blocks} blocks from Peer {Peer} " +
"(tip: #{TipIndex} {TipHash})",
logSessionId,
subSessionId,
receivedBlockCountCurrentLoop,
peer.Address.ToHex(),
workspace.Tip?.Index,
workspace.Tip?.Hash
);
break;
}
}
private async Task ProcessFillBlocks(
TimeSpan timeout,
CancellationToken cancellationToken
)
{
var sessionRandom = new Random();
IComparer <BlockPerception> canonComparer = BlockChain.Policy.CanonicalChainComparer;
while (!cancellationToken.IsCancellationRequested)
{
int sessionId = sessionRandom.Next();
if (!(BlockDemand is { } blockDemand))
{
await Task.Delay(1, cancellationToken);
continue;
}
BoundPeer peer = blockDemand.Peer;
try
{
if (canonComparer.Compare(
BlockChain.PerceiveBlock(BlockDemand?.Header),
BlockChain.PerceiveBlock(BlockChain.Tip)
) <= 0)
{
using (await _blockSyncMutex.LockAsync(cancellationToken))
{
BlockDemand = null;
continue;
}
}
var hash = new BlockHash(blockDemand.Header.Hash);
const string startLogMsg =
"{SessionId}: Got a new " + nameof(BlockDemand) + " from {Peer}; started " +
"to fetch the block #{BlockIndex} {BlockHash}...";
_logger.Debug(startLogMsg, sessionId, peer, blockDemand.Header.Index, hash);
await SyncPreviousBlocksAsync(
blockChain : BlockChain,
peer : peer,
stop : hash,
progress : null,
timeout : timeout,
totalBlockCount : 0,
logSessionId : sessionId,
cancellationToken : cancellationToken
);
_logger.Debug(
"{SessionId}: Synced block(s) from {Peer}; broadcast them to neighbors...",
sessionId,
peer
);
// FIXME: Clean up events
BlockReceived.Set();
BlockAppended.Set();
BroadcastBlock(peer.Address, BlockChain.Tip);
ProcessFillBlocksFinished.Set();
}
catch (TimeoutException)
{
const string msg =
"{SessionId}: Timeout occurred during " + nameof(ProcessFillBlocks) +
"() from {Peer}.";
_logger.Debug(msg, sessionId, peer);
}
catch (InvalidBlockIndexException ibie)
{
const string msg =
"{SessionId}: " + nameof(InvalidBlockIndexException) + " occurred during " +
nameof(ProcessFillBlocks) + "() from {Peer}: {Exception}";
_logger.Warning(ibie, msg, sessionId, peer, ibie);
}
catch (Exception e)
{
const string msg =
"{SessionId}: Unexpected exception occurred during " +
nameof(ProcessFillBlocks) + "() from {Peer}: {Exception}";
_logger.Error(e, msg, sessionId, peer, e);
}
finally
{
using (await _blockSyncMutex.LockAsync(cancellationToken))
{
const string msg =
"{SessionId}: " + nameof(ProcessFillBlocks) + "() finished.";
_logger.Debug(msg, sessionId);
if (BlockDemand.Equals(blockDemand))
{
const string resetMsg =
"{SessionId}: Reset " + nameof(BlockDemand) + "...";
_logger.Debug(resetMsg, sessionId);
BlockDemand = null;
}
}
}
}
}
private async Task SyncPreviousBlocksAsync(
BlockChain <T> blockChain,
BoundPeer peer,
BlockHash?stop,
IProgress <BlockDownloadState> progress,
TimeSpan timeout,
long totalBlockCount,
int logSessionId,
CancellationToken cancellationToken
)
{
long previousTipIndex = blockChain.Tip?.Index ?? -1;
BlockChain <T> synced = null;
try
{
long currentTipIndex = blockChain.Tip?.Index ?? -1;
long receivedBlockCount = currentTipIndex - previousTipIndex;
const string startMsg = "{SessionId}: Starts " + nameof(FillBlocksAsync) + "()...";
_logger.Debug(startMsg, logSessionId);
FillBlocksAsyncStarted.Set();
synced = await FillBlocksAsync(
peer,
blockChain,
stop,
progress,
totalBlockCount,
receivedBlockCount,
true,
timeout,
logSessionId,
cancellationToken
);
const string finishMsg = "{SessionId}: Finished " + nameof(FillBlocksAsync) + "().";
_logger.Debug(finishMsg, logSessionId);
}
catch (Exception)
{
FillBlocksAsyncFailed.Set();
throw;
}
finally
{
var canonComparer = BlockChain.Policy.CanonicalChainComparer;
if (synced is { } syncedB &&
!syncedB.Id.Equals(blockChain?.Id) &&
(!(blockChain.Tip is { } tip&& syncedB.Tip is { } syncedTip) ||
canonComparer.Compare(
blockChain.PerceiveBlock(tip),
blockChain.PerceiveBlock(
syncedTip,
syncedB.PerceiveBlock(syncedTip).PerceivedTime
)
) < 0
)
)
{
_logger.Debug(
"{SessionId}: Swap the chain {ChainIdA} for the chain {ChainIdB}...",
logSessionId,
blockChain.Id,
synced.Id
);
blockChain.Swap(
synced,
render: true,
stateCompleters: null
);
_logger.Debug(
"{SessionId}: The chain {ChainIdB} replaced {ChainIdA}",
logSessionId,
synced.Id,
blockChain.Id
);
}
}
}