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);
}
}
public async Task AddTransactions(IEnumerable <ByteString> transactions)
{
List <byte[]> transactionHashes = new List <byte[]>();
List <Record> lockedRecords = new List <Record>();
byte[] lockToken = Guid.NewGuid().ToByteArray();
try {
foreach (ByteString rawTransaction in transactions)
{
byte[] rawTransactionBuffer = rawTransaction.ToByteArray();
Transaction transaction = MessageSerializer.DeserializeTransaction(rawTransaction);
byte[] transactionHash = MessageSerializer.ComputeHash(rawTransactionBuffer);
byte[] mutationHash = MessageSerializer.ComputeHash(transaction.Mutation.ToByteArray());
Mutation mutation = MessageSerializer.DeserializeMutation(transaction.Mutation);
List <byte[]> records = new List <byte[]>();
#if DEBUG
Logger.LogDebug($"Add transaction {new ByteString(transactionHash)} token {new ByteString(lockToken)}");
#endif
transactionHashes.Add(transactionHash);
// add pending transaction
var ptr = new MongoDbPendingTransaction
{
MutationHash = mutationHash,
TransactionHash = transactionHash,
RawData = rawTransactionBuffer,
LockTimestamp = DateTime.UtcNow,
InitialRecords = new List <MongoDbRecord>(),
AddedRecords = new List <byte[]>(),
LockToken = lockToken
};
await PendingTransactionCollection.InsertOneAsync(ptr);
// lock records
foreach (var r in mutation.Records)
{
var previous = await LockRecord(lockToken, r);
if (previous != null)
{
ptr.InitialRecords.Add(previous);
lockedRecords.Add(r);
}
else
if (r.Value != null)
{
ptr.AddedRecords.Add(r.Key.ToByteArray());
lockedRecords.Add(r);
}
}
// save original records
await PendingTransactionCollection.UpdateOneAsync(
x => x.TransactionHash.Equals(transactionHash),
Builders <MongoDbPendingTransaction> .Update
.Set(x => x.InitialRecords, ptr.InitialRecords)
.Set(x => x.AddedRecords, ptr.AddedRecords)
);
// update records
foreach (var rec in mutation.Records)
{
MongoDbRecord r = BuildMongoDbRecord(rec);
if (r.Value == null)
{
if (r.Version.Length == 0) // No record expected
{
var res = await RecordCollection.CountAsync(x => x.Key.Equals(r.Key));
if (res != 0) // a record exists
{
throw new ConcurrentMutationException(rec);
}
}
else
{ // specific version expected
var res = await RecordCollection.CountAsync(x => x.Key.Equals(r.Key) && x.Version.Equals(r.Version));
if (res != 1) // expected version not found
{
throw new ConcurrentMutationException(rec);
}
}
}
else
{
if (r.Version.Length == 0)
{
r.Version = mutationHash;
r.TransactionLock = lockToken;
try {
await RecordCollection.InsertOneAsync(r);
} catch (MongoWriteException ex) when(ex.WriteError.Category == ServerErrorCategory.DuplicateKey)
{
throw new ConcurrentMutationException(rec);
}
}
else
{
var res = await RecordCollection.UpdateOneAsync(
x => x.Key.Equals(r.Key) && x.Version.Equals(r.Version) && x.TransactionLock.Equals(lockToken),
Builders <MongoDbRecord> .Update
.Set(x => x.Value, r.Value)
.Set(x => x.Version, mutationHash)
);
if (res.MatchedCount != 1 || res.ModifiedCount != 1)
{
throw new ConcurrentMutationException(rec);
}
}
records.Add(r.Key);
}
}
// add transaction
var tr = new MongoDbTransaction {
MutationHash = mutationHash,
TransactionHash = transactionHash,
RawData = rawTransactionBuffer,
Records = records
};
await TransactionCollection.InsertOneAsync(tr);
}
// unlock records
List <ByteString> l = new List <ByteString>();
foreach (var r in lockedRecords)
{
if (!l.Contains(r.Key))
{
await UnlockRecord(lockToken, r);
l.Add(r.Key);
}
}
// remove pending transaction
foreach (var hash in transactionHashes)
{
await PendingTransactionCollection.DeleteOneAsync(x => x.TransactionHash.Equals(hash));
}
#if DEBUG
Logger.LogDebug($"Transaction committed token {new ByteString(lockToken)}");
#endif
}
catch (Exception ex1)
{
#if DEBUG
Logger.LogDebug($"Error committing transaction batch {ex1.Message} token {new ByteString(lockToken)}");
#endif
foreach (var hash in transactionHashes)
{
#if DEBUG
Logger.LogDebug($"Rollbacking transaction 0 {new ByteString(hash)}");
#endif
try
{
await RollbackTransaction(hash);
} catch (Exception ex2)
{
throw new AggregateException(ex2, ex1);
}
}
throw;
}
}