Transaction table and userpoint table data inconsistent

Our userpoints and userpoints_txn tables are inconsistent. Some of the transactions are not resulting in matching updates in the "cache" -- the userpoints table.

This is a sign of a larger problem.

There are two tables being updated on every "userpoint transaction" and this is fundamentally wrong. If any of the queries or checks fails, there is going to be inconsistency. Example, from _userpoints_transaction function:

    db_query('UPDATE {userpoints_txn} SET '. implode(', ', $arr) .' 
              WHERE txn_id = %d',
              $params['txn_id']
            );
    _userpoints_update_cache($params);

If db_query fails for any of a million reasons, _userpoints_update_cache will be called anyway, resulting in inconsistency.

Another example, from #407356: Error in _userpoints_update_cache() prevents awarding or removing uncategorized points from users:

  if (!isset($params['tid'])) {
    $params['tid'] = NULL;
  }

Results in failed query in _userpoints_update_cache. So the original "transaction" wont be reflected in the "cache".

Proposed solution:

• Rewrite _userpoints_update_cache so it recalculates the cache from data in userpoints_txn table instead of the running sum based on the new transaction and existing data in userpoints table that it is doing now
• In addition, the _userpoints_update_cache should be called after each transaction, failed or not, the cost is minimal. This ensures that any future inconsistencies are automatically fixed after the next transaction.

I think these two changes will ensure that the two tables will stay consistent eradicating a whole family of existing bugs that we will chase forever. I am willing to provide a patch if there is interest from a maintainer.