// used to wrap every access to the dataGrid in a transaction
private <T> T doWithinBackingTransactionIfNeeded(Callable<T> command) {
boolean inTopLevel = false;
boolean commandFinished = false;
try {
if (!dataGrid.inTransaction()) {
dataGrid.beginTransaction();
inTopLevel = true;
}
T result = command.call();
commandFinished = true;
return result;
} catch (Exception e) {
throw new PersistenceException(e);
} finally {
if (inTopLevel) {
try {
if (commandFinished) {
dataGrid.commitTransaction();
} else {
dataGrid.rollbackTransaction();
}
} catch (Exception e) {
throw new PersistenceException(e);
}
}
}
}
