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https://issues.apache.org/jira/browse/HTTPCLIENT-1395?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Nikola Petrov updated HTTPCLIENT-1395:
--------------------------------------

    Description: 
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

  was:
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 implementation can 
control if the client should check for a more recent version in the cache

    
> 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
>         Attachments: 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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