Added a conccurrent version of the sortable lazy list.

[ripdajacker]

We ran into some issues with very fast updates to a MGrid using a ListContainer with a SortableLazyList.

The issue occurred during a call to getItemIds in the list container.
This calls lazyList.subList() which, in our application, threw ArrayIndexOutOfBoundsException.
This was caused by the list being updated from our datasource (rest service) during an iteration.

[vonloxley]

Wouldn’t it be better to move tryLock() out of this try-block? Otherwise the finally might try to unlock a non-existing lock and throw (another) exception.

[ripdajacker]

Yes that would be a better solution.

[ripdajacker]

I added the proposed change to the latest commit.

[mstahv]

Hi,

Sorry it took bit long to answer, I have been too busy with V8 release lately.

Are you using the same container for multiple components/users?

Is this slightly related to #280 ?

Do you think we could also have a test for this?

cheers,
matti

[ripdajacker]

Hey,

The container in question is used by one user, but the view listens for changes in the underlying datastructure.
So you can request a page count and expect n elements, but between your count() call and your findEntitites() call something was deleted.

#280 has a somewhat related symptom, but is still subject to race conditions when the underlying data changes. My pull request will probably resolve said issue.