internal void LogWrite <T>(StmObject <T> stmObject, T newValue)
{
var newStmObject = new StmObject <T>(newValue);
var txEntry = _txLog.GetObject(stmObject);
if (txEntry == null)
{
txEntry = TransactionLogEntry <T> .LogWriteEntry(stmObject, newStmObject);
_txLog.Add(txEntry);
return;
}
txEntry.UpdateNewStmObject(newStmObject);
}
private bool IsValidVersion <T>(TransactionLogEntry <T> txEntry)
{
//// validate on each read only if
//// a.) serializability is asked for
//// b.) the object´s data working set
//// could have changed since the last read. that´s only the case if clonemode=cloneOnWrite.
//// (no validation for PassingReadOnly reads!)
//if (txEntry.ReadOption > StmReadOption.PassingReadOnly
// && _isolationLevel == StmTransactionIsolationLevel.Serializable
// && _cloneMode == StmTransactionCloneMode.CloneOnWrite)
//{
// // isolevel "serializable": the value must not have changed since it was last read
// return stmObject.Version == txEntry.Version;
//}
//// isolevel "readcommitted": the value is allowed to be changed by another tx
//return true;
var versionId = txEntry.OriginalObject.Element.Version;
//var loop = 0;
//while (versionId is int == false && loop < 3)
//{
// Thread.Sleep(300);
// loop++;
//}
bool waitMore;
do
{
if (versionId is int)
{
return((int)versionId == (int)txEntry.OriginalVersionId);
}
waitMore = txEntry.OriginalObject.ResetEvent.Wait(1000);
versionId = txEntry.OriginalObject.Element.Version;
} while (versionId is int == false && waitMore);
throw new StmObjectBusyException("StmObject busy could not read");
}
internal T LogRead <T>(StmObject <T> stmObject)
{
var txEntry = _txLog.GetObject(stmObject);
if (txEntry == null)
{
// first read on object: create txlog entry...
var newStmObject = stmObject.Clone();
txEntry = TransactionLogEntry <T> .LogReadEntry(stmObject, newStmObject);
_txLog.Add(txEntry);
// return new value
return(newStmObject.Value);
}
if (IsValidVersion(txEntry))
{
return(txEntry.NewObject.Value);
}
throw new StmObjectValueChangedException("StmObject value has been changed by another transaction since it was last read. (Use isolation level 'ReadCommitted' to allow such changes to happen.)");
}
