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Posted to dev@hc.apache.org by "Oleg Kalnichevski (JIRA)" <ji...@apache.org> on 2015/01/12 10:47:35 UTC
[jira] [Updated] (HTTPCLIENT-1395) Call the storage implementation
only once on a cache miss
[ https://issues.apache.org/jira/browse/HTTPCLIENT-1395?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Oleg Kalnichevski updated HTTPCLIENT-1395:
------------------------------------------
Fix Version/s: (was: 4.4 Final)
5.0
> Call the storage implementation only once on a cache miss
> ---------------------------------------------------------
>
> Key: HTTPCLIENT-1395
> URL: https://issues.apache.org/jira/browse/HTTPCLIENT-1395
> Project: HttpComponents HttpClient
> Issue Type: Improvement
> Components: HttpCache
> Affects Versions: 4.2.5
> Reporter: Nikola Petrov
> Priority: Minor
> Fix For: 5.0
>
> Attachments: call-storage-implementation-once-4.2-branch.patch, call-storage-implementation-once-trunk.patch, call-storage-implementation-once.patch
>
>
> I am trying to use the httpclient-cache component with a Cassandra backend. Everything seems good except that HttpCacheStorage#getEntry is getting called 3 times the first time resulting in a performance bottleneck. There might be a way to handle this in the Storage implementation by caching the recently queried values but I think that a better place is in the CachingHttpClient class. The current code expects zero latency to the storage backend(the current implementations are all memory based) but here is a patch that fixes the problem. Some notes:
> * I am using the code from the 4.2.5 release(but can port the code to the current trunk)
> * test is provided in org.apache.http.impl.client.cache.TestCachingHttpClient
> * BasicHttpCache is patched to expose methods that check if the key is found or if a proper variant is found - without this there is no way to say if there was a real cache miss or the specific variant is missing
> * CachingHttpClient is checking if the current HttpCache implementation is BasicHttpCache so it can use the new methods - I didn't want to change the interface because this will add breaking changes to the API
> * This exposes the alreadyHaveNewerCacheEntry method so implementations can control if the client should check for a more recent version in the cache
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