[TS-1439] Replace functionality of TSHttpTxnNewCacheLookupDo

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Component/s: TS API
• Assignee: Phil Sorber
• Reporter: Leif Hedstrom
• Created: 05/Sep/12 22:12
• Updated: 11/Jun/15 17:03
• Resolved: 11/Jun/15 17:03

Description

We have a set of APIs (in ts/experimtental.h) to do a "second" CacheSM / cache lookup from a plugin API. This includes the API TSHttpTxnNewCacheLookupDo(). We now also have a plugin that depends on this behavior, mostly as a side effect (it wants the second cache lookup, but with the same cache key).

I think the implementation of this is rather unfortunate, having a second CacheSM where you provide a second cache URL (to parse / MD5 etc.) to perform this second lookup. It would be noticeably cleaner to be able to reuse the CacheSM, and move the HttpSM back in the state chain, to retry a cache lookup again. This would allow a plugin to retry cache lookups any number of times for example, and also lets us unify on a single cache key API.

The latter is important for some of the changes I would like to do around the cacheURL. Right now, we store (and set) the cache URL, which means that a plugin who wishes to change the cache key has to create an artificial URL, which gets parsed, and then turned into an MD5. We should eliminate this, and provide Set/Get APIs to manipulate the (one and only) CacheSM's MD5 cache-key directly from the APIs. This could be via a URL, but could be done on whatever the plugin would prefer (e.g. an MD5 of a combination of the URL and the request headers).

Issue Links

• Is contained by: TS-1118 Modify how we manage the cache key / MD5 / lookup_url in the CacheSM / HttpSM.
• is duplicated by: TS-3165 Cache Toolkit API
• relates to: TS-2920 Stale_While_revalidate