[GitHub] incubator-hawq issue #1379: WIP: Cache UGI objects and clean them periodical...

[benchristel <gi...@git.apache.org>]

Github user benchristel commented on the issue:

    https://github.com/apache/incubator-hawq/pull/1379
  
    What's our approach to testing this going to be? Also, the cache should be a separate class IMO since its behavior and data don't really cohere with `SecurityServletFilter`. Something like:
    
    ```java
    class UserGroupInformationCache {
      public UserGroupInformation get(SegmentTransactionId session) { /* ... */ }
      public void removeStaleUGIs(long currentTimeMillis)  { /* ... */ }
    }
    ```
    
    This interface assumes we will have some other thread outside this class that periodically calls `removeStaleUGIs` with the current time. We could also have the cache start its own cleanup thread, but then we'd have to `sleep` in our tests to observe the UGIs getting cleaned up, which could make the tests slow and flaky.


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