public async Task <bool> Transact(GrainTransactionData <TDeltaState> transaction, int index)
{
// setting TransactionId locks record as pending, on silo failure OnActivateAsync recovers it
State.TransactionId = transaction.TransactionId;
State.TransactionDelta = transaction.Values[index].Item2;
TransferTimestamp = DateTime.Now.ToOADate();
if (!Commit(State.TransactionDelta))
{
return(false);
}
if (State.Reminder == null)
{
// the reminder ensures that recovery will occur on silo failure
// once a reminder is set, it can be reused for multiple transactions
string name = "TransactionGrain" + this.GetPrimaryKey();
// make sure the reminder occurs before the TransactionStatusPool purges status for this transaction
TimeSpan WAKEUP_PERIOD = TimeSpan.FromMinutes(TransactionStatusPoolHelper.PURGE_PERIOD_MINUTES / 2);
State.Reminder = await this.RegisterOrUpdateReminder(name, WAKEUP_PERIOD, WAKEUP_PERIOD);
}
await base.WriteStateAsync();
int nextindex = index + 1;
if (nextindex >= transaction.Values.Count)
{
// we have reached the end of the transaction, record that it's complete then unwind the stack
var transactionStatus = GrainFactory.GetGrain <ITransactionStatusPool>(TransactionStatusPoolHelper.GetHash(State.TransactionId));
await transactionStatus.SetComplete(State.TransactionId);
}
else
{
bool exceptionThrown = false;
try
{
if (!await transaction.Values[nextindex].Item1.Transact(transaction, nextindex))
{
// a member considers this transaction illegal, rollback
Rollback(State.TransactionDelta);
State.TransactionId = default(Guid);
return(false);
}
}
catch
{
exceptionThrown = true;
}
if (exceptionThrown)
{
// if an exception is thrown we are left in a state where it is unclear if the transaction completed
// use the TransactionStatus grain to ensure that all grains either commit or roll back atomically
await CheckForPendingTransaction();
}
}
// clear transaction delay persisting for performance till ReceiveReminder
// OnActivateAsync will check TransactionStatus on silo crash
IsTransactionPersistenceRequired = true;
State.TransactionId = default(Guid);
return(true);
}
private async Task CheckForPendingTransaction()
{
if (State.TransactionId != default(Guid))
{
var transactionStatus = GrainFactory.GetGrain <ITransactionStatusPool>(TransactionStatusPoolHelper.GetHash(State.TransactionId));
bool success = await transactionStatus.IsComplete(State.TransactionId);
if (success)
{
State.TransactionId = default(Guid);
}
else
{
Console.WriteLine("Rolling back the transaction because it never completed.");
Rollback(State.TransactionDelta);
State.TransactionId = default(Guid);
}
}
}
