[
https://issues.apache.org/jira/browse/HTTPCLIENT-427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12863495#action_12863495
]
David Mays commented on HTTPCLIENT-427:
---------------------------------------
The idea behind Variant URIs is that for a resource that has Vary response
headers, we store a "parent" cache entry, which has pointers (variant URIs) to
"child" entries. The child entries will contain the "variable" content for that
resource. So the parent entry becomes the map to find a given child entry,
where the URI (cache key) has had a string like {Content-Encoding:gzip}
prepended to it
So you might have a parent entry like this:
"http://www.example.com/foo";
With children like these:
"{Content-Encoding:gzip}http://www.example.com/foo"; (Caused by a request that
had Accept-Encoding:gzip header)
"{Content-Encoding:identity}http://www.example.com/foo"; (Caused by a request
that had Accept-Encoding:identity header)
The idea of keeping the list of variant children with the parent entry is so
that we can clean up all child entries when a parent is invalidated. It
prevents orphan cache entries.
Regarding the atomic updates, we had also started working on a patch for that,
where CacheEntry had a new constructor that took everything you need, instead
of the HttpResponse. Obviously all the other setters were to be removed also.
This way, every time a cache entry is "pulled" from the cache, it is
effectively a copy, rather than a reference.
The CacheEntryUpdater class would have to be changed slightly to work with
this, but would not be especially difficult to do.
Dave
> Implement a cache to perform real request only when needed
> ----------------------------------------------------------
>
> Key: HTTPCLIENT-427
> URL: https://issues.apache.org/jira/browse/HTTPCLIENT-427
> Project: HttpComponents HttpClient
> Issue Type: Improvement
> Components: HttpClient
> Environment: Operating System: Linux
> Platform: PC
> Reporter: Marc Guillemot
> Fix For: 4.1 Alpha2
>
> Attachments: caching_client.zip, httpclient-cache.zip
>
>
> Browsers may cache received content according to the values of different
> response headers. It would be great if HttpClient could do the same.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
