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https://issues.apache.org/jira/browse/KAFKA-3499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15243852#comment-15243852
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ASF GitHub Bot commented on KAFKA-3499:
---------------------------------------

GitHub user guozhangwang opened a pull request:

    https://github.com/apache/kafka/pull/1229

    KAFKA-3499: prevent array typed keys in KeyValueStore

    

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/guozhangwang/kafka K3499

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/kafka/pull/1229.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #1229
    
----
commit 718b8f1423d885c5bee32bacbcacf4fb78598372
Author: Guozhang Wang <wangg...@gmail.com>
Date:   2016-04-15T00:26:57Z

    wrap segments keys with ByteBuffer

commit 9302bc18c8fa400b1fb7d4b36f29c8f0c812785c
Author: Guozhang Wang <wangg...@gmail.com>
Date:   2016-04-15T23:35:36Z

    prevent array keys in key value store

----


> byte[] should not be used as Map key nor Set member
> ---------------------------------------------------
>
>                 Key: KAFKA-3499
>                 URL: https://issues.apache.org/jira/browse/KAFKA-3499
>             Project: Kafka
>          Issue Type: Sub-task
>          Components: streams
>            Reporter: josh gruenberg
>            Assignee: Guozhang Wang
>              Labels: user-experience
>             Fix For: 0.10.0.0
>
>
> On the JVM, Array.equals and Array.hashCode do not incorporate array 
> contents; they inherit Object.equals/hashCode. This implies that Collections 
> that rely upon equals/hashCode (eg, HashMap/HashSet and variants) treat two 
> arrays with equal contents as distinct elements.
> Many of the Kafka Streams internal classes currently use generic HashMaps and 
> Sets to manage caches and invalidation status. For example, 
> RocksDBStore.cacheDirtyKeys is a HashSet<K>. Then, in RocksDBWindowStore, the 
> Elements are constructed as RocksDBStore<byte[], byte[]>.
> Similarly, the MemoryLRUCache<K, RocksDBCacheEntry> internally holds a 
> LinkedHashMap<K,V> map, and a HashSet<K> keys, and these end up holding 
> byte[] keys. Finally, user-code may attempt to use any of these provided 
> types with byte[], with undesirable results.
> Keys that are byte-arrays should be wrapped in a type that incorporates the 
> content in their computation of equals/hashCode. java.nio.ByteBuffer is one 
> such type that could be used, but a purpose-built immutable class would 
> likely be a better solution.



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