internal Task Notify(CancellationToken token)
{
// Not syncing until the StartHash has been set.
if (this.StartHash == null)
{
return(Task.CompletedTask);
}
// Not syncing until the chain is downloaded at least up to this block.
ChainedHeader startBlock = this.Chain.GetBlock(this.StartHash);
if (startBlock == null)
{
return(Task.CompletedTask);
}
// Sets the location of the puller to the block preceding the one we want to receive.
ChainedHeader previousBlock = this.Chain.GetBlock(startBlock.Height > 0 ? startBlock.Height - 1 : 0);
this.Puller.SetLocation(previousBlock);
this.tip = previousBlock;
this.logger.LogTrace("Puller location set to block: {0}.", previousBlock);
// Send notifications for all the following blocks.
while (!this.ReSync)
{
token.ThrowIfCancellationRequested();
LookaheadResult lookaheadResult = this.Puller.NextBlock(token);
if (lookaheadResult.Block != null)
{
// Broadcast the block to the registered observers.
this.signals.SignalBlockConnected(lookaheadResult.Block);
this.tip = this.Chain.GetBlock(lookaheadResult.Block.GetHash());
continue;
}
// In reorg we reset the puller to the fork.
// When a reorg happens the puller is pushed back and continues from the current fork.
// Find the location of the fork.
while (this.Chain.GetBlock(this.tip.HashBlock) == null)
{
this.tip = this.tip.Previous;
}
// Set the puller to the fork location.
this.Puller.SetLocation(this.tip);
}
this.ReSync = false;
return(Task.CompletedTask);
}
/// <summary>
/// A puller method that will continuously loop and ask for the next block in the chain from peers.
/// The block will then be passed to the consensus validation.
/// </summary>
/// <remarks>
/// If the <see cref="Block"/> returned from the puller is <c>null</c> that means the puller is signaling a reorg was detected.
/// In this case a rewind of the <see cref="CoinView"/> db will be triggered to roll back consensus until a block is found that is in the best chain.
/// </remarks>
private async Task PullerLoopAsync()
{
this.logger.LogTrace("()");
while (!this.nodeLifetime.ApplicationStopping.IsCancellationRequested)
{
BlockValidationContext blockValidationContext = new BlockValidationContext();
using (new StopwatchDisposable(o => this.Validator.PerformanceCounter.AddBlockFetchingTime(o)))
{
// Save the current consensus tip to later check if it changed.
ChainedBlock consensusTip = this.Tip;
this.logger.LogTrace("Asking block puller to deliver next block.");
// This method will block until the next block is downloaded.
LookaheadResult lookaheadResult = this.Puller.NextBlock(this.nodeLifetime.ApplicationStopping);
if (lookaheadResult.Block == null)
{
using (await this.consensusLock.LockAsync(this.nodeLifetime.ApplicationStopping).ConfigureAwait(false))
{
this.logger.LogTrace("No block received from puller due to reorganization.");
if (!consensusTip.Equals(this.Tip))
{
this.logger.LogTrace("Consensus tip changed from '{0}' to '{1}', no rewinding.", consensusTip, this.Tip);
continue;
}
this.logger.LogTrace("Rewinding.");
await this.RewindCoinViewLockedAsync().ConfigureAwait(false);
continue;
}
}
blockValidationContext.Block = lookaheadResult.Block;
blockValidationContext.Peer = lookaheadResult.Peer;
}
this.logger.LogTrace("Block received from puller.");
await this.AcceptBlockAsync(blockValidationContext).ConfigureAwait(false);
}
this.logger.LogTrace("(-)");
}