[TS-974] TS should have a mode to hold partial objects in cache

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.0.1
• Fix Version/s: 7.1.0
• Component/s: Cache
• Labels: A
• Assignee: Alan M. Carroll
• Reporter: William Bardwell
• Created: 04/Oct/11 21:00
• Updated: 22/Sep/16 05:38

Description

For ATS to do an excelent job caching large files like video it would need to be able to hold partial objects for a large file. This could be done in a plugin or in the core. This would need to be integrated with the Range handling code to serve requests out of the partial objects and to get more parts of a file to satisfy a Range request.

An intermediate step (also do-able in the core or in a plugin) would be to have some settings to let the Range handling code be able to trigger a full file download either asynchronously when a Range response indicates that the file isn't larger than some threshold, or synchronously when a Range request could reasonably be answered quickly from a full request. (Right now Range requests are tunneled if there is not full cached content as far as I can tell.)

Issue Links

• contains: TS-658 HTTP SM holds the cache write lock for too long
• incorporates: TS-1776 Range requests not working right
• is depended upon by: TS-2166 Response header to ua has two "Content-Range" field
• is depended upon by: TS-2918 collapsed_connection Plugin Errors
• is depended upon by: TS-2920 Stale_While_revalidate
• is depended upon by: TS-3086 Range requests for stale cache entries never use If-Modified-Since/If-None-Match
• is depended upon by: TS-3182 collapsed_connection plugin
• is depended upon by: TS-1809 Remove HTTP_CACHE build option
• is related to: TS-3395 Hit ratio drops with high concurrency
• is related to: TS-2554 New plugin: detect 206 responses from origin, and do a background fill on the entire object
• is related to: TS-3269 Remove remnants of CACHE_RTSP_TYPE and mixt/MIXT.
• relates to: TS-2761 Weird behavior of read-while-write
• relates to: TS-3768 Implement a tiered back-off in read-while-writer retries
• relates to: TS-3431 enable_read_while_writer delays requests for mis-matched HTTP methods
• relates to: TS-475 HTTP SM should support efficient byte range requests
• relates to: TS-3348 Read while write config and range issues
• relates to: TS-3587 Support stale-while-revalidate in the core
• relates to: TS-1996 Remove TSHttpTxnNewCacheLookupDo API
• relates to: TS-4781 Port HTTPRangeSpec to master.
• relates to: TS-683 range_offset_limit behaviour the same as squid
• supercedes: TS-3175 Follow up on review comments on TS-2314
• supercedes: TS-61 Multiple do_io_pread on a CacheVConnection