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Evicting cache based on a particular element value being modified [message #1238706]

Sun, 02 February 2014 05:24

Anil Bhatia

Messages: 23
Registered: February 2011

Junior Member

I also noticed behavior similar to what is mentioned here http://www.eclipse.org/forums/index.php/mv/msg/639125/1233703/#msg_1233703

In my scenario, I have a higher level model element (close to the root, and this element is populated only once by the user, it does not occur again in the model).

Based upon the populated value, I have to do some expensive computation in scope provider, to customize the scope for some lower level elements.

I want to put the result of computation into cache, and redo the computation only when user comes back to this element, and changes its value.

Isn't there a way to tie eviction of a cache entry with a particular model element, saying - do not evict this cache entry, unless this model element value is modified, irrespective of whether the call is from inferrer, validator, or label provider...?

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Re: Evicting cache based on a particular element value being modified [message #1241766 is a reply to message #1238706]

Sat, 08 February 2014 13:31

Anil Bhatia

Messages: 23
Registered: February 2011

Junior Member

Since nobody responded, sorry if my question was absurd...
But going by the number of views this question has, I assume lot of people might be interested in the answer....

I tried solving this problem by using OnChangeEvictingCache#execWithoutCacheClear, by providing IUnitOfWork#exec, and returning instance of object I want to cache from exec.
That did not seem to help at all.

I am willing to try if there are any more options.
Alternatively, can someone point me to any documentation on how to implement custom caching.

Thanks
Anil

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Re: Evicting cache based on a particular element value being modified [message #1241786 is a reply to message #1241766]

Sat, 08 February 2014 14:17

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Why do you want to cache at all maybe you can achieve it on another
way.

I don't know any docs on how to implement the cache yourself

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Re: Evicting cache based on a particular element value being modified [message #1241860 is a reply to message #1241786]

Sat, 08 February 2014 17:02

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

btw did you try to simply overwrite org.eclipse.xtext.util.OnChangeEvictingCache.CacheAdapter.clearValues()

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: Evicting cache based on a particular element value being modified [message #1241896 is a reply to message #1241860]

Sat, 08 February 2014 18:23

Anil Bhatia

Messages: 23
Registered: February 2011

Junior Member

Overriding org.eclipse.xtext.util.OnChangeEvictingCache.CacheAdapter.clearValues() is surely a good idea.
So, for that do I need to override org.eclipse.xtext.util.OnChangeEvictingCache.getOrCreate(Resource)..? if yes (or no), how..?

Thanks
Anil

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Re: Evicting cache based on a particular element value being modified [message #1241906 is a reply to message #1241896]

Sat, 08 February 2014 18:43

Anil Bhatia

Messages: 23
Registered: February 2011

Junior Member

What I really mean to ask is - how do I bind my implementation so that it gets invoked..? I am using @Inject to get instance of cache as follows in my ScopeProvider:

@Inject
private OnChangeEvictingCache cache;

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Re: Evicting cache based on a particular element value being modified [message #1241921 is a reply to message #1241906]

Sat, 08 February 2014 19:15

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

what about directly using your class there?

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: Evicting cache based on a particular element value being modified [message #1241926 is a reply to message #1241921]

Sat, 08 February 2014 19:29

Anil Bhatia

Messages: 23
Registered: February 2011

Junior Member

Seems to work just the way I wanted. Thanks a lot for the simple hint Christian.

So now my overridden implementation of clearValues() is just empty. I guess, that means this cache is never evicted.
I hope that does not lead to memory leakage (or built up). Can you please clarify..?

Thanks
Anil

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