add support for nested transactions

while here:
- don't allow to copy/move DbConnector

src/dbconnector.cpp

@@ -51,16 +51,9 @@ DbConnector::DbConnector()
 	expression_allocated = false;
 	log = nullptr;
 	log_queries = false;
+	transaction_index = 0;
 }
 
-DbConnector::DbConnector(const DbConnector &)
-{
-	db_expression = nullptr;
-	expression_allocated = false;
-	log = nullptr;
-}
-
-
 DbConnector::~DbConnector()
 {
 	deallocate_expression();
@@ -173,6 +166,206 @@ bool DbConnector::query_remove(const pt::TextStream & stream, QueryResult & quer
 }
 
 
+bool DbConnector::begin()
+{
+	bool status = false;
+
+	if( transaction_index > 0 )
+	{
+		pt::TextStream str;
+		str << "SAVEPOINT savepoint_" << transaction_index;
+		status = DbConnector::query(str);
+	}
+	else
+	{
+		status = DbConnector::query("BEGIN");
+	}
+
+	if( status )
+	{
+		transaction_index += 1;
+	}
+	else
+	{
+		if( log )
+		{
+			(*log) << pt::Log::log1 << "Morm: I cannot start a transaction" << pt::Log::logend;
+		}
+	}
+
+	return status;
+}
+
+
+bool DbConnector::begin_if_needed()
+{
+	bool status = true;
+
+	if( transaction_index == 0 )
+	{
+		status = begin();
+	}
+
+	return status;
+}
+
+
+bool DbConnector::rollback()
+{
+	return rollback(transaction_index);
+}
+
+
+bool DbConnector::commit()
+{
+	return commit(transaction_index);
+}
+
+
+
+bool DbConnector::rollback_one_transaction(size_t index)
+{
+	bool status = false;
+
+	if( index > 1 )
+	{
+		pt::TextStream str;
+		str << "ROLLBACK TO SAVEPOINT savepoint_" << (index - 1);
+		status = DbConnector::query(str);
+		transaction_index = index - 1; // decrement it even if rollback failed
+	}
+	else
+	if( index == 1 )
+	{
+		status = DbConnector::query("ROLLBACK");
+		transaction_index = 0;
+	}
+
+	return status;
+}
+
+
+
+
+bool DbConnector::rollback(size_t index)
+{
+	bool status = false;
+
+	if( index == 0 )
+	{
+		if( log )
+		{
+			(*log) << pt::Log::log1 << "Morm: there is no a transaction with zero index - skipping rollback";
+		}
+	}
+	else
+	if( index > transaction_index )
+	{
+		if( log )
+		{
+			(*log) << pt::Log::log1 << "Morm: transaction";
+
+			if( index > 1 )
+				(*log) << " for savepoint_" << (index-1);
+
+			(*log) << " does not exist - skipping rollback" << pt::Log::logend;
+		}
+	}
+	else
+	{
+		status = true;
+
+		for(size_t i = transaction_index ; i >= index ; --i)
+		{
+			if( !rollback_one_transaction(i) )
+			{
+				/*
+				 * return false if at least one rollback failed
+				 */
+				status = false;
+			}
+		}
+	}
+
+	return status;
+}
+
+
+bool DbConnector::commit_one_transaction(size_t index)
+{
+	bool status = false;
+
+	if( index > 1 )
+	{
+		pt::TextStream str;
+		str << "RELEASE SAVEPOINT savepoint_" << (index - 1);
+		status = DbConnector::query(str);
+		transaction_index = index - 1;
+	}
+	else
+	if( index == 1 )
+	{
+		status = DbConnector::query("COMMIT");
+		transaction_index = 0;
+	}
+
+	return status;
+}
+
+
+bool DbConnector::commit(size_t index)
+{
+	bool status = false;
+
+	if( index == 0 )
+	{
+		if( log )
+		{
+			(*log) << pt::Log::log1 << "Morm: there is no a transaction with zero index - skipping commit";
+		}
+	}
+	else
+	if( index > transaction_index )
+	{
+		if( log )
+		{
+			(*log) << pt::Log::log1 << "Morm: transaction";
+
+			if( index > 1 )
+				(*log) << " for savepoint_" << (index-1);
+
+			(*log) << " does not exist - skipping commit" << pt::Log::logend;
+		}
+	}
+	else
+	{
+		status = true;
+
+		for(size_t i = transaction_index ; i >= index ; --i)
+		{
+			if( !commit_one_transaction(i) )
+			{
+				/*
+				 * return false if at least one commit failed
+				 */
+				status = false;
+			}
+		}
+	}
+
+	return status;
+}
+
+
+
+
+
+size_t DbConnector::get_transaction_index()
+{
+	return transaction_index;
+}
+
+
 
 DbExpression * DbConnector::get_expression()
 {

src/dbconnector.h

@@ -52,7 +52,8 @@ class DbConnector
 public:
 
 	DbConnector();
-	DbConnector(const DbConnector &);
+	DbConnector(const DbConnector &) = delete;
+	DbConnector(DbConnector &&) = delete;
 	virtual ~DbConnector();
 
 	virtual void set_logger(pt::Log * log);
@@ -91,6 +92,39 @@ public:
 	virtual bool query_insert(const pt::TextStream & stream, QueryResult & query_result);
 	virtual bool query_remove(const pt::TextStream & stream, QueryResult & query_result);
 
+	/*
+	 * create a new transaction
+	 * first transaction has index equal to one
+	 */
+	virtual bool begin();
+
+	/*
+	 * create a new transaction if there is no a transaction started yet
+	 */
+	virtual bool begin_if_needed();
+
+	/*
+	 * rollback or commit the last transaction
+	 */
+	virtual bool rollback();
+	virtual bool commit();
+
+	/*
+	 * rollback or commit all transactions from the last one to the index
+	 * (first transaction has index one, there is no a transaction with index zero)
+	 *
+	 */
+	virtual bool rollback(size_t index);
+	virtual bool commit(size_t index);
+
+	/*
+	 * return current transaction index
+	 * first transaction has index equal to one
+	 * returns zero if there are no any transactions
+	 */
+	virtual size_t get_transaction_index();
+
+
 	virtual void get_value(const char * value_str, char & field_value, 					const FT & field_type = FT::default_type);
 	virtual void get_value(const char * value_str, unsigned char & field_value, 		const FT & field_type = FT::default_type);
 	virtual void get_value(const char * value_str, wchar_t & field_value, 				const FT & field_type = FT::default_type);
@@ -141,6 +175,7 @@ protected:
 	bool expression_allocated;
 	pt::Log * log;
 	bool log_queries;
+	size_t transaction_index;
 
 
 	virtual void allocate_default_expression() = 0;
@@ -161,6 +196,9 @@ protected:
 	virtual void unescape_bin_string(const char * str, std::string & out);
 	virtual void unescape_bin_string(const char * str, std::wstring & out);
 
+	virtual bool rollback_one_transaction(size_t index);
+	virtual bool commit_one_transaction(size_t index);
+
 
 private:
 
@@ -169,8 +207,6 @@ private:
 
 
 
-
-
 };
 
 

src/postgresqlconnector.cpp

@@ -302,7 +302,6 @@ bool PostgreSQLConnector::query_remove(const pt::TextStream & stream, QueryResul
 
 
 
-
 //void PostgreSQLConnector::CreateIdList(const std::vector<long> & id_tab, std::wstring & list, bool add_parentheses)
 //{
 //wchar_t buffer[50];

src/transaction.cpp

@@ -44,6 +44,7 @@ Transaction::Transaction(ModelConnector * model_connector)
 	this->model_connector = model_connector;
 	is_transaction_started = false;
 	is_transaction_successful = true;
+	transaction_index = 0;
 	begin();
 }
 
@@ -53,6 +54,7 @@ Transaction::Transaction(ModelConnector * model_connector, bool auto_begin_trans
 	this->model_connector = model_connector;
 	is_transaction_started = false;
 	is_transaction_successful = true;
+	transaction_index = 0;
 
 	if( auto_begin_transaction )
 	{
@@ -106,6 +108,7 @@ void Transaction::set_successful(bool is_successful)
 
 bool Transaction::begin()
 {
+	bool status = false;
 	pt::Log * log = get_logger();
 
 	if( is_transaction_started )
@@ -118,7 +121,16 @@ bool Transaction::begin()
 		rollback(); // what if there is an error here? skip it at the moment
 	}
 
-	bool status = do_query("BEGIN");
+	if( model_connector )
+	{
+		DbConnector * db_connector = model_connector->get_db_connector();
+
+		if( db_connector )
+		{
+			status = db_connector->begin();
+			transaction_index = db_connector->get_transaction_index();
+		}
+	}
 
 	if( status )
 	{
@@ -129,11 +141,6 @@ bool Transaction::begin()
 	{
 		is_transaction_started = false;
 		is_transaction_successful = false;
-
-		if( log )
-		{
-			(*log) << pt::Log::log1 << "Morm: I cannot start a transaction" << pt::Log::logend;
-		}
 	}
 
 	return status;
@@ -159,12 +166,18 @@ bool Transaction::rollback()
 
 	if( is_transaction_started )
 	{
-		status = do_query("ROLLBACK");
-
-		if( status )
+		if( model_connector )
 		{
-			is_transaction_started = false;
+			DbConnector * db_connector = model_connector->get_db_connector();
+
+			if( db_connector )
+			{
+				status = db_connector->rollback(transaction_index);
+			}
 		}
+
+		// set it to false even if rollack failed
+		is_transaction_started = false;
 	}
 	else
 	{
@@ -186,12 +199,18 @@ bool Transaction::commit()
 
 	if( is_transaction_started )
 	{
-		status = do_query("COMMIT");
-
-		if( status )
+		if( model_connector )
 		{
-			is_transaction_started = false;
+			DbConnector * db_connector = model_connector->get_db_connector();
+
+			if( db_connector )
+			{
+				status = db_connector->commit(transaction_index);
+			}
 		}
+
+		// set it to false even if commit failed
+		is_transaction_started = false;
 	}
 	else
 	{
@@ -220,27 +239,6 @@ bool Transaction::finish()
 }
 
 
-
-
-bool Transaction::do_query(const char * query)
-{
-	bool status = false;
-
-	if( model_connector )
-	{
-		DbConnector * db_connector = model_connector->get_db_connector();
-
-		if( db_connector )
-		{
-			status = db_connector->query(query);
-		}
-	}
-
-	return status;
-}
-
-
-
 pt::Log * Transaction::get_logger()
 {
 	pt::Log * logger = nullptr;

src/transaction.h

@@ -68,9 +68,9 @@ protected:
 	ModelConnector * model_connector;
 	bool is_transaction_started;
 	bool is_transaction_successful;
+	size_t transaction_index;
 
-	bool do_query(const char * query);
-	pt::Log * get_logger();
+	virtual pt::Log * get_logger();
 
 
 private: