/// <summary>
///
/// </summary>
/// <param name="lockType"></param>
/// <param name="tables"></param>
/// <returns>false if thread grants access, false if thread is in a queue</returns>
public bool AddSession(eTransactionTablesLockTypes lockType, string[] tables)
{
lock (lock_disposed)
{
if (disposed)
{
return(true);
}
}
internSession iSession = null;
bool ret = true;
_sync.EnterWriteLock();
try
{
foreach (var ses in _acceptedSessions)
{
if (DbUserTables.TableNamesIntersect(ses.Value.tables.ToList(), tables.ToList()))
{
if (ses.Value.lockType == eTransactionTablesLockTypes.EXCLUSIVE || lockType == eTransactionTablesLockTypes.EXCLUSIVE)
{
//Lock
ret = false;
break;
}
}
}
if (!ret)
{
internSession xSes = null;
foreach (var ses in _waitingSessionSequence)
{
if (ses == Environment.CurrentManagedThreadId)
{
break;
}
_waitingSessions.TryGetValue(ses, out xSes);
if (DbUserTables.TableNamesIntersect(xSes.tables.ToList(), tables.ToList()))
{
if (xSes.lockType == eTransactionTablesLockTypes.EXCLUSIVE || lockType == eTransactionTablesLockTypes.EXCLUSIVE)
{
//Lock
ret = false;
break;
}
}
}
}
if (_waitingSessions.TryGetValue(Environment.CurrentManagedThreadId, out iSession))
{
//This session was in the waiting list once
if (ret)
{
//We have to take away session from waiting list
iSession.gator.Dispose();
iSession.gator = null;
_waitingSessions.Remove(Environment.CurrentManagedThreadId);
_waitingSessionSequence.Remove(Environment.CurrentManagedThreadId);
}
else
{
iSession.gator.CloseGate();
}
}
else
{
//Creating new session
iSession = new internSession()
{
lockType = lockType,
tables = tables
};
if (!ret)
{
iSession.gator = new DbThreadsGator(false);
_waitingSessions.Add(Environment.CurrentManagedThreadId, iSession);
_waitingSessionSequence.Add(Environment.CurrentManagedThreadId);
}
}
if (ret)
{
//Adding into accepted sessions
_acceptedSessions.Add(Environment.CurrentManagedThreadId, iSession);
}
}
finally
{
_sync.ExitWriteLock();
}
if (!ret)
{
//putting gate
iSession.gator.PutGateHere();
}
return(ret);
}
/// <summary>
/// Access synchronizer.
/// All calls of the WRITE LOCATOR come over this function.
/// </summary>
/// <param name="transactionThreadId"></param>
/// <param name="tablesNames"></param>
/// <param name="calledBySynchronizer"></param>
public void RegisterWriteTablesForTransaction(int transactionThreadId, List <string> tablesNames, bool calledBySynchronizer)
{
//in every transaction unit we got a list of reserved for WRITING tables
//if we have in tablesNames one of the tables which is in this list we have to stop the thread with mre
bool toWaitTillTransactionIsFinished = false;
bool breakOuterLoop = false;
TransactionUnit transactionUnit = null;
bool deadlock = false;
//When SyncTables is called
//Console.WriteLine(DateTime.UtcNow.ToString("dd.MM.yyyy HH:mm:ss") + "> SYNC IN Thread: " + transactionThreadId);
while (true) //loop till thread will get full access to write tables
{
toWaitTillTransactionIsFinished = false;
breakOuterLoop = false;
deadlock = false;
//Console.WriteLine(DateTime.UtcNow.ToString("dd.MM.yyyy HH:mm:ss") + "> " + "Thread: " + transactionThreadId + "WHILE ");
//only tables required for writing or read-commited will have to go over this fast bottleneck
lock (_sync_dl)
{
_sync_transactions.EnterReadLock();
try
{
this._transactions.TryGetValue(transactionThreadId, out transactionUnit);
if (transactionUnit == null)
{
return; //transaction doesn't exist anymore, gracefully goes out
}
if (!calledBySynchronizer)
{
//Here we are in case if Registrator is called by WriteTableCall, so we check intersections
//Between reserved Write tables and current table using patterns intersections technique.
//If they intersect we let the thread to proceed
if (DbUserTables.TableNamesIntersect(transactionUnit.GetTransactionWriteTablesNames(), tablesNames))
{
return;
}
}
//iterating over all open transactions except self, finding out if desired tables are locked by other threads.
foreach (var tu in this._transactions.Where(r => r.Value.TransactionThreadId != transactionThreadId))
{
foreach (string tableName in tu.Value.GetTransactionWriteTablesNames())
{
//if (tablesNames.Contains(tableName))
if (DbUserTables.TableNamesContains(tablesNames, tableName))
{
//
//++++++++++++++ here we can register all tables which are waiting for write lock release
transactionUnit.AddTransactionWriteTablesAwaitingReservation(tablesNames);
//++++++++++++++ if thread, who has locked this table has another table in a "waiting for reservation" blocked by this thread - it's a deadlock
//if (transactionUnit.GetTransactionWriteTablesNames().Intersect(tu.Value.GetTransactionWriteTablesAwaitingReservation()).Count() > 0)
if (DbUserTables.TableNamesIntersect(transactionUnit.GetTransactionWriteTablesNames(), tu.Value.GetTransactionWriteTablesAwaitingReservation()))
{
//we got deadlock, we will stop this transaction with an exception
deadlock = true;
}
//other thread has reserved table for the transaction we have to wait
toWaitTillTransactionIsFinished = true;
breakOuterLoop = true;
if (!deadlock)
{
//Console.WriteLine(DateTime.UtcNow.ToString("dd.MM.yyyy HH:mm:ss") + "> " + "Thread: " + transactionThreadId + " GATE IS CLOSED ");
ThreadsGator.CloseGate(); //closing gate only if no deadlock situation
//mreWriteTransactionLock.Reset(); //setting to signalled only in non-deadlock case
}
break;
}
}
if (breakOuterLoop)
{
break;
}
}
}
catch (System.Exception ex)
{
this.UnregisterTransaction(transactionThreadId);
throw DBreezeException.Throw(DBreezeException.eDBreezeExceptions.TRANSACTION_TABLE_WRITE_REGISTRATION_FAILED, ex);
}
finally
{
_sync_transactions.ExitReadLock();
}
//if(true) this thread owns all table for modification lock
if (!toWaitTillTransactionIsFinished)
{
//+++++++++++ Here we can clear all table names in the waiting reservation queue
transactionUnit.ClearTransactionWriteTablesAwaitingReservation(tablesNames);
//we have to reserve for our transaction all tables
foreach (var tbn in tablesNames)
{
transactionUnit.AddTransactionWriteTable(tbn, null);
}
//Console.WriteLine(DateTime.UtcNow.ToString("dd.MM.yyyy HH:mm:ss") + "> SYNC OUT Thread: " + transactionThreadId + " Sync stop: " + transactionUnit.udtSyncStop.ToString("dd.MM.yyyy HH:mm:ss"));
return;
}
}//end of lock
if (deadlock)
{
this.UnregisterTransaction(transactionThreadId);
throw DBreezeException.Throw(DBreezeException.eDBreezeExceptions.TRANSACTION_IN_DEADLOCK);
}
if (toWaitTillTransactionIsFinished)
{
//Console.WriteLine(DateTime.UtcNow.ToString("dd.MM.yyyy HH:mm:ss") + "> " + "Thread: " + transactionThreadId + " GATE IS PUT ");
//blocking thread which requires busy tables for writing, till they are released
//ThreadsGator.PutGateHere(20000); //every 20 second (or by Gate open we give a chance to re-try, for safety reasons of hanged threads, if programmer didn't dispose DBreeze process after the programm end)
//#if ASYNC
// await ThreadsGator.PutGateHere().ConfigureAwait(false);
//#else
// ThreadsGator.PutGateHere();
//#endif
ThreadsGator.PutGateHere();
//mreWriteTransactionLock.WaitOne();
}
}//eo while
}
/// <summary>
/// Access synchronizer.
/// All calls of the WRITE LOCATOR come over this function.
/// </summary>
/// <param name="transactionThreadId"></param>
/// <param name="tablesNames"></param>
public void RegisterWriteTablesForTransaction(int transactionThreadId, List <string> tablesNames, bool calledBySynchronizer)
{
//in every transaction unit we got a list of reserved for WRITING tables
//if we have in tablesNames one of the tables which is in this list we have to stop the thread with mre
bool toWaitTillTransactionIsFinished = false;
bool breakOuterLoop = false;
TransactionUnit transactionUnit = null;
bool deadlock = false;
Exception innerException = null;
while (true) //loop till thread will get full access to write tables
{
toWaitTillTransactionIsFinished = false;
breakOuterLoop = false;
deadlock = false;
//only tables required for writing or read-commited will have to go over this fast bottleneck
lock (_sync_dl)
{
_sync_transactions.EnterReadLock();
try
{
this._transactions.TryGetValue(transactionThreadId, out transactionUnit);
if (transactionUnit == null)
{
return; //transaction doesn't exist anymore, gracefully goes out
}
if (!calledBySynchronizer)
{
//Here we are in case if Registrator is called by WriteTableCall, so we check intersections
//Between reserved Write tables and current table using patterns intersections technique.
//If they intersect we let the thread to proceed
if (DbUserTables.TableNamesIntersect(transactionUnit.GetTransactionWriteTablesNames(), tablesNames))
{
return;
}
//Help for the programmer on the early stage to see problem with the possible deadlock
if (_engine.Configuration.NotifyAhead_WhenWriteTablePossibleDeadlock)
{
if (transactionUnit.TransactionWriteTablesCount > 0)
{
throw new Exception("Put table \"" + tablesNames.FirstOrDefault() + "\" into tran.SynchronizeTables statement, because it will be modified");
}
}
}
//iterating over all open transactions except self, finding out if desired tables are locked by other threads.
foreach (var tu in this._transactions.Where(r => r.Value.TransactionThreadId != transactionThreadId))
{
foreach (string tableName in tu.Value.GetTransactionWriteTablesNames())
{
//if (tablesNames.Contains(tableName))
if (DbUserTables.TableNamesContains(tablesNames, tableName))
{
//
//++++++++++++++ here we can register all tables which are waiting for write lock release
transactionUnit.AddTransactionWriteTablesAwaitingReservation(tablesNames);
//++++++++++++++ if thread, who has locked this table has another table in a "waiting for reservation" blocked by this thread - it's a deadlock
//if (transactionUnit.GetTransactionWriteTablesNames().Intersect(tu.Value.GetTransactionWriteTablesAwaitingReservation()).Count() > 0)
if (DbUserTables.TableNamesIntersect(transactionUnit.GetTransactionWriteTablesNames(), tu.Value.GetTransactionWriteTablesAwaitingReservation()))
{
//we got deadlock, we will stop this transaction with an exception
deadlock = true;
}
//other thread has reserved table for the transaction we have to wait
toWaitTillTransactionIsFinished = true;
breakOuterLoop = true;
if (!deadlock)
{
ThreadsGator.CloseGate(); //closing gate only if no deadlock situation
//mreWriteTransactionLock.Reset(); //setting to signalled only in non-deadlock case
}
break;
}
}
if (breakOuterLoop)
{
break;
}
}
}
catch (System.Exception ex)
{
innerException = ex;
//this.UnregisterTransaction(transactionThreadId);
//throw DBreezeException.Throw(DBreezeException.eDBreezeExceptions.TRANSACTION_TABLE_WRITE_REGISTRATION_FAILED,ex);
}
finally
{
_sync_transactions.ExitReadLock();
}
if (innerException != null)
{
this.UnregisterTransaction(transactionThreadId);
throw DBreezeException.Throw(DBreezeException.eDBreezeExceptions.TRANSACTION_TABLE_WRITE_REGISTRATION_FAILED, innerException);
}
//if(true) this thread owns all table for modification lock
if (!toWaitTillTransactionIsFinished)
{
//+++++++++++ Here we can clear all table names in the waiting reservation queue
transactionUnit.ClearTransactionWriteTablesAwaitingReservation(tablesNames);
//we have to reserve for our transaction all tables
foreach (var tbn in tablesNames)
{
transactionUnit.AddTransactionWriteTable(tbn, null);
}
return;
}
}//end of lock
if (deadlock)
{
this.UnregisterTransaction(transactionThreadId);
throw DBreezeException.Throw(DBreezeException.eDBreezeExceptions.TRANSACTION_IN_DEADLOCK);
}
if (toWaitTillTransactionIsFinished)
{
//blocking thread which requires busy tables for writing, till they are released
//ThreadsGator.PutGateHere(20000); //every 20 second (or by Gate open we give a chance to re-try, for safety reasons of hanged threads, if programmer didn't dispose DBreeze process after the programm end)
ThreadsGator.PutGateHere();
//mreWriteTransactionLock.WaitOne();
}
}
}
