private async Task <LedgerAnchor> ComputeNewAnchor(LedgerAnchor lastAnchor)
{
IReadOnlyList <ByteString> newTransactions;
byte[] currentHash;
if (lastAnchor != null)
{
newTransactions = await storageEngine.GetTransactions(lastAnchor.Position);
currentHash = lastAnchor.FullStoreHash.ToByteArray();
}
else
{
newTransactions = await storageEngine.GetTransactions(null);
currentHash = new byte[32];
}
if (newTransactions.Count == 0)
{
return(null);
}
byte[] position = currentHash;
byte[] buffer = new byte[64];
using (SHA256 sha = SHA256.Create())
{
foreach (ByteString rawTransaction in newTransactions)
{
currentHash.CopyTo(buffer, 0);
position = MessageSerializer.ComputeHash(rawTransaction.ToByteArray());
position.CopyTo(buffer, 32);
currentHash = sha.ComputeHash(sha.ComputeHash(buffer));
}
}
LedgerAnchor result = new LedgerAnchor(
new ByteString(position),
new ByteString(currentHash),
newTransactions.Count + (lastAnchor != null ? lastAnchor.TransactionCount : 0));
return(result);
}
/// <summary>
/// Determines whether a new anchor should be calculated and recorded,
/// and does it if it is the case.
/// </summary>
/// <returns>The task object representing the asynchronous operation.</returns>
public async Task <LedgerAnchor> RecordAnchor()
{
if (await anchorRecorder.CanRecordAnchor())
{
LedgerAnchor anchor = await anchorState.GetLastAnchor();
LedgerAnchor latestAnchor = await ComputeNewAnchor(anchor);
if (latestAnchor != null)
{
// Record the anchor
await anchorRecorder.RecordAnchor(latestAnchor);
// Commit the anchor if it has been recorded successfully
await anchorState.CommitAnchor(latestAnchor);
return(latestAnchor);
}
}
return(null);
}