[xwiki-devs] Way of corrupting the Document Cache

Hi devs, We've identified yesterday one scenario when the doc cache can become corrupted. By corrupted I mean having a document in it which is empty and has isNew set to true. Here it is: * Imagine we're doing a hibernate query calling XHS.execute() (executeRead()/executeWrite()). We're thus in a hibernate session/transaction * Now imagine that in the doInHibernate callback we start another request. * Also imagine that the first query was executed in the "wiki1" wiki (setDatabase has been called and the DB is positionned in this wiki) * Now imagine that the second nested query is done on a different wiki (for example asking to get the user doc from the main wiki) * The result will be that the doc will not be found by hibernate and loadXWikiDoc will return a new doc with isNew set to true * The doc cache will save this new doc in the cache * Subsequent calls for this document will return the invalid document (with isNew = true) This is what was happening for http://jira.xwiki.org/browse/XWIKI-8160, the problem being that HqlQueryExecutor was doing 2 nested queries. JV is fixing this today. I'm reporting this here because it's important not to do nested queries like. We're going to generate an exception when we do to try to locate them if there are any more. Thanks -Vincent