private bool ShouldCheckpoint(TransactionMap txManager, out List <BeginTransactionOperationLogRecord> abortTxList)
{
abortTxList = null;
// There is a checkpoint in progres. So return false
if (this.logManager.LastInProgressCheckpointRecord != null)
{
return(false);
}
if (ShouldInitiatePeriodicCheckpoint())
{
return(true);
}
var bytesUsedFromLastCheckpoint = this.GetBytesUsed(this.logManager.LastCompletedBeginCheckpointRecord);
// If there is enough data to checkpoint, we should try to look for 'bad' transactions that are preventing
// enough data from being checkpointed
if (bytesUsedFromLastCheckpoint <= this.checkpointIntervalBytes)
{
return(false);
}
var earliestPendingTx = txManager.GetEarliestPendingTransaction();
// If there is no pending tx, we should checkpoint now
if (earliestPendingTx == null)
{
return(true);
}
// The earliest pending tx is very new and it has not yet been flushed. So it is fine to checkpoint
// This could ALSO imply that we have a really old Tx that has not been flushed and has been lying around in the buffers
// However, the latter case is taken care of by throttling the incoming operations based on "pending bytes" that are unflushed
if (earliestPendingTx.RecordPosition == LogRecord.InvalidRecordPosition)
{
return(true);
}
var oldTxOffset = this.GetCurrentTailPosition() - this.txnAbortThresholdInBytes - 1;
// The transaction is new enough. We can checkpoint
if (earliestPendingTx.RecordPosition > oldTxOffset)
{
return(true);
}
// Get all 'bad' transactions that are preventing us from checkpointing enough state
// We will return 'false' now and the next group commit should successfully checkpoint since the earliest pending should be newer
abortTxList = txManager.GetPendingTransactionsOlderThanPosition(oldTxOffset);
return(false);
}
public List <BeginTransactionOperationLogRecord> GetOldTransactions(TransactionMap txManager)
{
var tail = this.GetCurrentTailPosition();
// The tail is smaller than truncate interval
if (tail <= this.txnAbortThresholdInBytes)
{
return(null);
}
var oldTxOffset = this.GetCurrentTailPosition() - this.txnAbortThresholdInBytes - 1;
// Get all 'bad' transactions that are preventing us from checkpointing enough state
return(txManager.GetPendingTransactionsOlderThanPosition(oldTxOffset));
}