private async Task <MongoDbTransaction> GetLastTransactionInternal()
{
// look for potential last transaction
var res = await TransactionCollection.Find(x => true)
.SortByDescending(x => x.Timestamp)
.FirstOrDefaultAsync();
if (res == null)
{
return(null);
}
// look if a pending transaction
var resp = await PendingTransactionCollection.Find(x => true).SortByDescending(x => x.Timestamp).FirstOrDefaultAsync();
if (resp == null) // no pending transaction
{
// return last transaction
return(res);
}
else
{
// else return last transaction no younger than pending transaction
res = await TransactionCollection.Find(x => x.Timestamp < resp.Timestamp)
.SortByDescending(x => x.Timestamp)
.FirstOrDefaultAsync();
return(res);
}
}
public async Task RollbackAllPendingTransactions(DateTime limit)
{
var res = await PendingTransactionCollection.Find(x => x.LockTimestamp < limit).ToListAsync();
foreach (var t in res)
{
await RollbackTransaction(t.TransactionHash);
}
}
private async Task RollbackTransaction(byte[] hash)
{
// Rollback is idempotent && reentrant : may be call twice even at the same time
try
{
#if DEBUG
Logger.LogDebug($"Rollbacking transaction {new ByteString(hash)}");
#endif
// get affected records
var trn = await PendingTransactionCollection.Find(x => x.TransactionHash.Equals(hash)).SingleOrDefaultAsync();
if (trn != null)
{
// revert records values & version
foreach (var r in trn.InitialRecords)
{
await RecordCollection.FindOneAndUpdateAsync(
x => x.Key.Equals(r.Key) && x.TransactionLock.Equals(trn.LockToken),
Builders <MongoDbRecord> .Update.Set(x => x.Value, r.Value).Set(x => x.Version, r.Version).Unset(x => x.TransactionLock)
);
}
foreach (var r in trn.AddedRecords)
{
await RecordCollection.FindOneAndDeleteAsync(
x => x.Key.Equals(r) && x.TransactionLock.Equals(trn.LockToken)
);
}
// remove transaction
await TransactionCollection.DeleteOneAsync(x => x.TransactionHash.Equals(hash));
await RecordCollection.UpdateOneAsync(
x => x.TransactionLock == trn.LockToken,
Builders <MongoDbRecord> .Update
.Unset(x => x.TransactionLock)
);
// remove pending transaction
await PendingTransactionCollection.DeleteOneAsync(x => x.TransactionHash.Equals(hash));
Logger.LogInformation($"Transaction {new ByteString(hash)} rollbacked");
}
}
catch (Exception ex)
{
var msg = "Error rollbacking transaction : " + new ByteString(hash).ToString();
Logger.LogCritical(msg, ex);
throw new Exception(msg, ex);
}
}
