[sakai-core-team] [Building Sakai] Java 8

[Matthew Buckett]

On 24 March 2015 at 11:39, Matthew Buckett <matthew.buckett at it.ox.ac.uk> wrote:
> I couldn't see any references to ConcurrentOrderedMap in the current
> Sakai codebase. The bug with EntityBroker tests failing should be
> fixed by:
>
> https://github.com/azeckoski/reflectutils/commit/4b33c37e8e29f3a260817d9218a5d32e145377aa
>
> which was a problem with the assumption that the superclass would call
> put() when putAll() was called.
>
> I'd just drop ConcurrentOrderedMap from reflectutils so that people
> don't start using it in the future.

Looking a little ConcurrentOrderedMap has a few issues:
- It loses the performance characteristics of ConcurrentHashMap as it
has an internal Vector which limits it's concurrency.
- #putIfAbsent(K, V) isn't thread safe. It calls containsKey and then
put, but doesn't do it atomically so it's not deterministic.
- #remove(key, value) isn't thread safe. It removes the entry from the
ConcurrentHashMap and then removes it from the internal Vector without
any locking (another thread could be adding in between this).

So I'd be even more incline to remove it as it's not really a good
implementation of the API and seems like it was just created for
completeness.

-- 
  Matthew Buckett, VLE Developer, IT Services, University of Oxford