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https://issues.apache.org/jira/browse/HTTPCLIENT-1099?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bart Robeyns updated HTTPCLIENT-1099:
-------------------------------------
Description:
It is not possible to alter the behaviour of the CachingHttpClient because the
policies defining the behaviour are private and tied directly to specific
implementations in the CachingHttpClients constructor. Furthermore, these
policies are package private, discouraging reuse and/or extensions.
Making this possible is easy enough (provide some policy-setters or
-constructor-args in CachingHttpClient and make the policy-classes public); the
attached patch allows custom Policies, extending the default ones to be set on
the CacheConfig class.
The specific case that led to this question:
A back-end application only sets its Content-Length header for responses below
8K. This response does get stored in the cache, but when retrieving it from the
cache, CacheValidityPolicy.contentLengthHeaderMatchesActualLength checks the
Content-Length header with the stored size (to verify whether the cached
content is complete). This check fails, causing the cache entry to be deemed
unusable. If we were able to provide our own subclassed CacheValidityPolicy, it
would be easy to skip the check if the header is missing and thus accomodate
this specific back-end quirk.
was:
It is not possible to alter the behaviour of the CachingHttpClient because the
policies defining the behaviour are private and tied directly to specific
implementations in the CachingHttpClients constructor. Furthermore, these
policies are package private, discouraging reuse and/or extensions.
Making this possible is easy enough (provide some policy-setters or
-constructor-args in CachingHttpClient and make the policy-classes public) -
which leads me to believe that the tight relationships between client and
policies is deliberate. Is this the case, or are you willing to accept a patch
that opens up these classes for extending the caching behaviour?
The specific case that lead to this question:
A back-end application only sets its Content-Length header for responses below
8K. This response does get stored in the cache, but when retrieving it from the
cache, CacheValidityPolicy.contentLengthHeaderMatchesActualLength checks the
Content-Length header with the stored size (to verify whether the cached
content is complete). This check fails, causing the cache entry to be deemed
unusable. If we were able to provide our own subclassed CacheValidityPolicy, it
would be easy to skip the check if the header is missing and thus accomodate
this specific back-end quirk.
> Overriding Caching Policies
> ---------------------------
>
> Key: HTTPCLIENT-1099
> URL: https://issues.apache.org/jira/browse/HTTPCLIENT-1099
> Project: HttpComponents HttpClient
> Issue Type: Improvement
> Components: Cache
> Affects Versions: 4.1.1
> Reporter: Bart Robeyns
> Priority: Minor
> Labels: cache, policy
> Attachments: OpenPolicies.patch
>
>
> It is not possible to alter the behaviour of the CachingHttpClient because
> the policies defining the behaviour are private and tied directly to specific
> implementations in the CachingHttpClients constructor. Furthermore, these
> policies are package private, discouraging reuse and/or extensions.
> Making this possible is easy enough (provide some policy-setters or
> -constructor-args in CachingHttpClient and make the policy-classes public);
> the attached patch allows custom Policies, extending the default ones to be
> set on the CacheConfig class.
> The specific case that led to this question:
> A back-end application only sets its Content-Length header for responses
> below 8K. This response does get stored in the cache, but when retrieving it
> from the cache, CacheValidityPolicy.contentLengthHeaderMatchesActualLength
> checks the Content-Length header with the stored size (to verify whether the
> cached content is complete). This check fails, causing the cache entry to be
> deemed unusable. If we were able to provide our own subclassed
> CacheValidityPolicy, it would be easy to skip the check if the header is
> missing and thus accomodate this specific back-end quirk.
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