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+//
+// Transaction.h
+//
+// Library: Data
+// Package: DataCore
+// Module:  Transaction
+//
+// Definition of the Transaction class.
+//
+// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+
+#ifndef Data_Transaction_INCLUDED
+#define Data_Transaction_INCLUDED
+
+
+#include "Poco/Data/Data.h"
+#include "Poco/Data/Session.h"
+#include "Poco/Logger.h"
+
+
+namespace Poco {
+namespace Data {
+
+
+class Data_API Transaction
+	/// Transaction helps with transactions in domain logic.
+	/// When an Transaction object is created, it first checks whether a
+	/// transaction is in progress. If not, a new transaction is created.
+	/// When the Transaction is destroyed, and commit() has been called,
+	/// nothing is done. Otherwise, the current transaction is rolled back.
+	/// See Transaction for more details and purpose of this template.
+{
+public:
+	Transaction(Poco::Data::Session& session, Poco::Logger* pLogger = 0);
+		/// Creates the Transaction and starts it, using the given database session and logger.
+
+	Transaction(Poco::Data::Session& session, bool start);
+		/// Creates the Transaction, using the given database session.
+		/// If start is true, transaction is started, otherwise begin() must be called
+		/// to start the transaction.
+		
+	template <typename T>
+	Transaction(Poco::Data::Session& rSession, T& t, Poco::Logger* pLogger = 0): 
+		_rSession(rSession),
+		_pLogger(pLogger)
+		/// Creates the Transaction, using the given database session, transactor and logger.
+		/// The transactor type must provide operator () overload taking non-const Session 
+		/// reference as an argument.
+		///
+		/// When transaction is created using this constructor, it is executed and
+		/// commited automatically. If no error occurs, rollback is disabled and does
+		/// not occur at destruction time. If an error occurs resulting in exception being
+		/// thrown, the transaction is rolled back and exception propagated to calling code.
+		/// 
+		/// Example usage:
+		/// 
+		/// struct Transactor
+		/// {
+		///		void operator () (Session& session) const
+		///		{
+		///			// do something ...
+		///		}
+		/// };
+		/// 
+		/// Transactor tr;
+		/// Transaction tn(session, tr); 
+	{
+		try { transact(t); }
+		catch (...)
+		{
+			if (_pLogger) _pLogger->error("Error executing transaction.");
+			rollback();
+			throw;
+		}
+	}
+
+	~Transaction();
+		/// Destroys the Transaction.
+		/// Rolls back the current database transaction if it has not been commited
+		/// (by calling commit()), or rolled back (by calling rollback()).
+		///
+		/// If an exception is thrown during rollback, the exception is logged
+		/// and no further action is taken. 
+
+	void setIsolation(Poco::UInt32 ti);
+		/// Sets the transaction isolation level.
+
+	Poco::UInt32 getIsolation();
+		/// Returns the transaction isolation level.
+
+	bool hasIsolation(Poco::UInt32 ti);
+		/// Returns true iff the transaction isolation level corresponding
+		/// to the supplied bitmask is supported.
+
+	bool isIsolation(Poco::UInt32 ti);
+		/// Returns true iff the transaction isolation level corresponds
+		/// to the supplied bitmask.
+
+	void execute(const std::string& sql, bool doCommit = true);
+		/// Executes and, if doCommit is true, commits the transaction.
+		/// Passing true value for commit disables rollback during destruction
+		/// of this Transaction object.
+
+	void execute(const std::vector<std::string>& sql);
+		/// Executes all the SQL statements supplied in the vector and, after the last
+		/// one is sucesfully executed, commits the transaction.
+		/// If an error occurs during execution, transaction is rolled back.
+		/// Passing true value for commit disables rollback during destruction
+		/// of this Transaction object.
+
+	template <typename T>
+	void transact(T& t)
+		/// Executes the transactor and, unless transactor throws an exception, 
+		/// commits the transaction.
+	{
+		if (!isActive()) begin();
+		t(_rSession);
+		commit();
+	}
+
+	void commit();
+		/// Commits the current transaction.
+		
+	void rollback();
+		/// Rolls back the current transaction.
+		
+	bool isActive();
+		/// Returns false after the transaction has been committed or rolled back,
+		/// true if the transaction is ongoing.
+
+	void setLogger(Poco::Logger* pLogger);
+		/// Sets the logger for this transaction.
+		/// Transaction does not take the ownership of the pointer.
+
+private:
+	Transaction();
+	Transaction(const Transaction&);
+	Transaction& operator = (const Transaction&);
+	
+	void begin();
+		/// Begins the transaction if the session is already not in transaction.
+		/// Otherwise does nothing.
+
+	Session _rSession;
+	Logger* _pLogger;
+};
+
+
+inline bool Transaction::isActive()
+{
+	return _rSession.isTransaction();
+}
+
+
+inline void Transaction::setIsolation(Poco::UInt32 ti)
+{
+	_rSession.setTransactionIsolation(ti);
+}
+
+
+inline Poco::UInt32 Transaction::getIsolation()
+{
+	return _rSession.getTransactionIsolation();
+}
+
+
+inline bool Transaction::hasIsolation(Poco::UInt32 ti)
+{
+	return _rSession.isTransactionIsolation(ti);
+}
+
+
+inline bool Transaction::isIsolation(Poco::UInt32 ti)
+{
+	return _rSession.isTransactionIsolation(ti);
+}
+
+
+inline void Transaction::setLogger(Poco::Logger* pLogger)
+{
+	_pLogger = pLogger;
+}
+
+
+} } // namespace Poco::Data
+
+
+#endif // Data_Transaction_INCLUDED