Transaction with binded thread connection in Spring - spring

Question

I want to bind a connection to a thread, and use that connection for any JdbcTemplate calls, to finally commit the changes or do a rollback.
I'm declaring all sentences from a Groovy script, so I can't control how many SQL query will be call, that's why I have to used this method and not a TransactionalTemplate or something like that. this script will call a helper class that will use that connection and JdbcTemplate, let's call that class SqlHelper.
Right now my non-working-as-needed solution is call from groovy script to that SqlHelper to initialize a transaction:
initTransaction(ecommerce)
which calls
public void initTransaction(DataSource dataSource) {
DefaultTransactionDefinition transactionDefinition = new DefaultTransactionDefinition();
transactionDefinition.setReadOnly(false);
transactionDefinition.setIsolationLevel(TransactionDefinition.ISOLATION_SERIALIZABLE);
// dataSourceTransactionManager.setDataSource(dataSource);
// dataSourceTransactionManager.setRollbackOnCommitFailure(true);
// dataSourceTransactionManager.setTransactionSynchronization(TransactionSynchronization.STATUS_COMMITTED);
// dataSourceTransactionManager.setDataSource(dataSource);
try {
Connection connection = DataSourceUtils.getConnection(dataSource);
connection.setAutoCommit(false);
DataSourceUtils.prepareConnectionForTransaction(connection, transactionDefinition);
} catch (CannotGetJdbcConnectionException e) {
throw new RuntimeException(e);
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
After that the script will call some SQL operations, like
sqlUpdate(ecommerce, insertSentence, insertParams)
which calls
public Integer update(DataSource dataSource, String sql, Map<String, Object> paramMap) {
return new NamedParameterJdbcTemplate(dataSource).update(sql, paramMap);
}
Finally I want to finish the transaction committing the changes using
commitTransaction(dataSource)
which calls
public void commitTransaction(DataSource dataSource) {
Connection connection = DataSourceUtils.getConnection(dataSource);
try {
connection.commit();
} catch (Exception e) {
rollbackTransaction(dataSource);
}
// DataSourceUtils.resetConnectionAfterTransaction(connection, TransactionDefinition.ISOLATION_DEFAULT);
// SimpleTransactionStatus transactionStatus = new SimpleTransactionStatus(false);
// try {
// dataSourceTransactionManager.commit(transactionStatus);
// jta.commit(transactionStatus);
// } catch (TransactionException e) {
// dataSourceTransactionManager.rollback(transactionStatus);
// throw new RuntimeException(e);
// }
}
private void rollbackTransaction(DataSource dataSource) {
Connection connection = DataSourceUtils.getConnection(dataSource);
try {
connection.rollback();
} catch (SQLException e) {
throw new RuntimeException(e);
}
DataSourceUtils.resetConnectionAfterTransaction(connection, TransactionDefinition.ISOLATION_DEFAULT);
}
I left commented blocks of some testing to show you what approaches I tried. I don't know very well how Spring transaction works, so I'm just trying different things and trying to learn how all this stuff works... I will provide you more information if you want ;)
Thank you in advance.
UPDATE
As M. Denium suggested, that's what I have for now:
I declared the variable, using the TransactionStatus as ThreadSafe and finally solved as:
private DataSourceTransactionManager dataSourceTransactionManager = null;
private DefaultTransactionDefinition transactionDefinition = null;
private static final ThreadLocal<TransactionStatus> transactionStatus = new ThreadLocal<TransactionStatus>() {
#Override
protected TransactionStatus initialValue() {
return null;
}
};
And then using the same call from Groovy script, using the helper methods:
public void initTransaction(DataSource dataSource) {
dataSourceTransactionManager = new DataSourceTransactionManager();
transactionDefinition = new DefaultTransactionDefinition();
transactionDefinition.setReadOnly(false);
transactionDefinition.setIsolationLevel(TransactionDefinition.ISOLATION_SERIALIZABLE);
dataSourceTransactionManager.setRollbackOnCommitFailure(true);
dataSourceTransactionManager.setTransactionSynchronization(TransactionSynchronization.STATUS_UNKNOWN);
dataSourceTransactionManager.setDataSource(dataSource);
transactionStatus.set(dataSourceTransactionManager.getTransaction(null));
}
public void commitTransaction() {
try {
LOG.info("Finishing transaction...");
dataSourceTransactionManager.commit(transactionStatus.get());
dataSourceTransactionManager.getDataSource().getConnection().close();
LOG.info("Done.");
} catch (Throwable e) {
dataSourceTransactionManager.rollback(transactionStatus.get());
throw new RuntimeException("An exception during transaction. Rolling back.");
}
}

Answer 1

You are trying to reimplement the things that are already implemented by the transaction abstraction of Spring. Simply use the proper PlatformTransactionManager (you can probably grab that from an ApplicationContext) keep a reference to the TransactionStatus instead of a DataSource and use that to commit/rollback.
public TransactionStatus initTransaction() {
return transactionManager.getTransaction(null);
}
public void commit(TransactionStatus status) {
transactionManager.commit(status);
}
Instead of passing the TransactionStatus around you could also store it in a ThreadLocal and retrieve it in the commit method. This would ease the pain.
Another tip you shouldn't be creating JdbcTemplates and NamedParameterJdbcTemplates those are heavy objects to create. Upon construction they consult a connection to determine which database and version this is needed for the exception conversion. So performance wise this isn't a smart thing to do. Create a single instance and reuse, the templates are thread safe so you would only be needing a single instance.
However I would strongly argue that you should actually be using Groovy and not to try to work around it. Groovy has the Sql class that can help you. You already have access to the DataSource so doing something like this would be all that is needed.
def sql = new Sql(dataSource);
sql.withTransaction {
sql.execute "INSERT INTO city (name, state, founded_year) VALUES ('Minneapolis', 'Minnesota', 1867)"
sql.execute "INSERT INTO city (name, state, founded_year) VALUES ('Orlando', 'Florida', 1875)"
sql.execute "INSERT INTO city (name, state, founded_year) VALUES ('Gulfport', 'Mississippi', 1887)"
}
This is plain Groovy, no need to develop additional classes or to write extensive documentation to get it working. Just Groovy...