Acceleo query cache
Some of our users have been bit by the fact that Acceleo caches the result of Query invocations, returning the very same result each time a given query is called. These users often came with the same two questions : "why?" and "Can this cache be disabled in my case?".
The answer to the first has always been and will remain the same : Acceleo is an implementation of the OMG's MOFM2T 1.0 specification, and this specification tells us that
A query is required to produce the same result each time it is invoked with the same arguments.That is the reason we decided to cache the result : in order to return that same result each time the query is called, without re-evaluating it.
The answer to the second, however, changes with the 3.1.0 release of Acceleo : even though we strive to be as close as possible to the specification, there are times where this caching of the query return values is not desirable : it can be really costly memory-wise, it could be a call to a Java method that has random results, it could be a query which return value changes according to variable states that are not passed as parameters... That was possible through programmatic calls in 3.0.2, but we've decided to make that preference available through the UI in 3.1.0 :
The next step is to have the specification evolve in order to be able to disable the query cache "per-query" instead of globally but... that's another story :).
The answer to the first has always been and will remain the same : Acceleo is an implementation of the OMG's MOFM2T 1.0 specification, and this specification tells us that
A query is required to produce the same result each time it is invoked with the same arguments.That is the reason we decided to cache the result : in order to return that same result each time the query is called, without re-evaluating it.
The answer to the second, however, changes with the 3.1.0 release of Acceleo : even though we strive to be as close as possible to the specification, there are times where this caching of the query return values is not desirable : it can be really costly memory-wise, it could be a call to a Java method that has random results, it could be a query which return value changes according to variable states that are not passed as parameters... That was possible through programmatic calls in 3.0.2, but we've decided to make that preference available through the UI in 3.1.0 :
The next step is to have the specification evolve in order to be able to disable the query cache "per-query" instead of globally but... that's another story :).
Auteur d'origine: Laurent