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https://issues.apache.org/jira/browse/SAMZA-505?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris Riccomini reassigned SAMZA-505:
-------------------------------------
Assignee: Chris Riccomini
> CachedStore doesn't support Array keys well
> -------------------------------------------
>
> Key: SAMZA-505
> URL: https://issues.apache.org/jira/browse/SAMZA-505
> Project: Samza
> Issue Type: Bug
> Components: kv
> Affects Versions: 0.8.0
> Reporter: Chris Riccomini
> Assignee: Chris Riccomini
> Fix For: 0.9.0
>
>
> Several people have hit an issue when using the Key/Value store with byte[]
> keys. Since CachedStore uses a HashMap, and Array.equals/Array.hashCode
> return object identity values, the HashMap behaves unexpectedly. This isn't
> really a bug, just a common misunderstanding in how things work. It's
> compounded by the fact that we default caches to "on". This yields the
> behavior:
> {code}
> store.put("a".getBytes, 1)
> store.get("a".getBytes) // returns null
> {code}
> See [this
> discussion|http://stackoverflow.com/questions/1058149/using-a-byte-array-as-hashmap-key-java]
> for details.
> Our TestKeyValueStore uses byte[] keys, but it keeps them in a list, and
> re-uses the same exact instance, so we don't hit this problem.
> I think we should wrap array keys in ByteBuffer, or use our own wrapper.
> We'll have to make sure to unwrap before calling the put/get/delete
> operations on the underlying store.
> Initially, I was thinking that the safest thing to do would be to have
> CachedStore check all keys, and throw an exception. This would allow
> individuals to choose the best course of action (ByteBuffer.wrap, use an
> alternative key, write a custom wrapper class, etc). But, I think this
> approach doesn't work in some cases. If there's a cache with a JSON serde,
> and the user is using a key of Array[Int], using the key of Array[Int] is
> valid. A JSON serde would just serialize it as [1,2,3], and everything should
> work in this case.
> Since this problem is basically an implementation detail introduced by
> CachedStore, I think it should be fixed internally by wrapping/unwrapping
> array keys.
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