private bool CheckDependenciesCompleted()
{
bool processed = false;
while (dependencyQueue.TryDequeue(out Transaction tx))
{
processed = true;
CommitRecord commitRecord = new CommitRecord
{
TransactionId = tx.TransactionId
};
foreach (var resource in tx.Info.WriteSet.Keys)
{
commitRecord.Resources.Add(resource);
}
groupCommitQueue.Enqueue(new Tuple <CommitRecord, Transaction>(commitRecord, tx));
this.SignalGroupCommitEnqueued();
// We don't need to hold the transaction lock any more to access
// the WaitingTransactions set, since nothing can be added to it
// after this point.
// If a transaction is waiting on us, decrement their waiting count;
// - if they are no longer waiting, mark as validated.
// TODO: Can't we clear WaitingTransactions here and no longer track it?
foreach (var waiting in tx.WaitingTransactions)
{
bool signal = false;
lock (waiting)
{
if (waiting.State != TransactionState.Aborted)
{
waiting.PendingCount--;
if (waiting.PendingCount == 0)
{
waiting.State = TransactionState.Validated;
dependencyQueue.Enqueue(waiting);
signal = true;
}
}
}
if (signal)
{
this.SignalDependencyEnqueued();
}
}
}
return(processed);
}
public async Task StartAsync()
{
await transactionLog.Initialize();
CommitRecord record = await transactionLog.GetFirstCommitRecord();
long prevLSN = 0;
while (record != null)
{
Transaction tx = new Transaction(record.TransactionId)
{
State = TransactionState.Committed,
LSN = record.LSN,
Info = new TransactionInfo(record.TransactionId)
};
if (prevLSN == 0)
{
checkpointedLSN = record.LSN - 1;
}
prevLSN = record.LSN;
foreach (var resource in record.Resources)
{
tx.Info.WriteSet.Add(resource, 1);
}
transactionsTable[record.TransactionId] = tx;
checkpointQueue.Enqueue(tx);
this.SignalCheckpointEnqueued();
record = await transactionLog.GetNextCommitRecord();
}
await transactionLog.EndRecovery();
var maxAllocatedTransactionId = await transactionLog.GetStartRecord();
activeTransactionsTracker.Start(maxAllocatedTransactionId);
this.BeginDependencyCompletionLoop();
this.BeginGroupCommitLoop();
this.BeginCheckpointLoop();
this.transactionLogMaintenanceTask = MaintainTransactionLog();
this.transactionLogMaintenanceTask.Ignore(); // protect agains unhandled exception in unexpected cases.
this.IsRunning = true;
}
