// Begin starts and returns a new transaction
// Only one transaction is supported at a time for a connection
func (c *connection) Begin() (driver.Tx, error) {
// Do not allow a new transaction if one already exists
if c.isTransactionActive {
return nil, fmt.Errorf("Transaction already active for connection")
}
ret := odbc.SQLSetConnectAttr(c.handle, odbc.SQL_ATTR_AUTOCOMMIT, odbc.SQLPOINTER(odbc.SQL_AUTOCOMMIT_OFF), 0, nil)
if isError(ret) {
return nil, errorConnection(c.handle)
}
c.isTransactionActive = true
tx := &transaction{conn: c}
return tx, nil
}
// Commit or rollback transaction in consistent manner
func (tx *transaction) completeTransaction(completeType odbc.SQLSMALLINT) error {
//Complete transaction by either committing or rolling back
ret := odbc.SQLEndTran(odbc.SQL_HANDLE_DBC, tx.conn.handle, completeType)
if isError(ret) {
return errorConnection(tx.conn.handle)
}
//Make transaction as finished and turn auto commit back on
tx.conn.isTransactionActive = false
ret = odbc.SQLSetConnectAttr(tx.conn.handle, odbc.SQL_ATTR_AUTOCOMMIT, odbc.SQLPOINTER(odbc.SQL_AUTOCOMMIT_ON), 0, nil)
if isError(ret) {
return errorConnection(tx.conn.handle)
}
return nil
}
// Close invalidates and potentially stops any current
// prepared statements and transactions, marking this
// connection as no longer in use.
func (c *connection) Close() error {
// Verify that connHandle is valid
if c.handle == 0 {
return nil
}
// Verify that connection has not already been closed
if c.isClosed {
return nil
}
var err error
// Close all of the statements owned by the connection
for key, _ := range c.statements {
// Skip the statement if it is already nil
if isNil(key) {
continue
}
key.Close()
}
c.statements = nil
// If the transaction is active, roll it back
if c.isTransactionActive {
ret := odbc.SQLEndTran(odbc.SQL_HANDLE_DBC, c.handle, odbc.SQL_ROLLBACK)
if isError(ret) {
err = errorConnection(c.handle)
}
//Turn AutoCommit back on
ret = odbc.SQLSetConnectAttr(c.handle, odbc.SQL_ATTR_AUTOCOMMIT, odbc.SQLPOINTER(odbc.SQL_AUTOCOMMIT_ON), 0, nil)
if isError(ret) {
err = errorConnection(c.handle)
}
}
// Disconnect connection
ret := odbc.SQLDisconnect(c.handle)
if isError(ret) {
err = errorConnection(c.handle)
}
// Deallocate connection
ret = odbc.SQLFreeHandle(odbc.SQL_HANDLE_DBC, c.handle)
if isError(ret) {
err = errorConnection(c.handle)
}
// Clear the handle
c.handle = 0
// Set connection to closed
c.isClosed = true
//Clear the finalizer
runtime.SetFinalizer(c, nil)
// Return any error
if err != nil {
return err
}
return nil
}