[squid-dev] [PATCH] Revalidate without Last-Modified

Eduard Bagdasaryan eduard.bagdasaryan at measurement-factory.com
Sat Aug 27 11:22:30 UTC 2016

2016-08-25 18:52 GMT+03:00 Alex Rousskov <rousskov at measurement-factory.com>:

 > 3. Sending an HTCP message to another service.
 > > -            hdr.putTime(Http::HdrType::LAST_MODIFIED, e->lastmod);
 > > +        if (e && e->lastModified() > -1)
 > > +            hdr.putTime(Http::HdrType::LAST_MODIFIED, 
 > Is this a conditional/revalidation request? If yes, then should we use
 > an effective modification time instead, like we do in use case #1?

I have not found what is the "conditional/revalidation" request from 
HTCP point
of view. The code snippet is taken from htcpTstReply(), serving replies 
for TST
requests (TST - test for the presence in the cache). If the entry is cached,
this method fills HTCP reply packet with some of cached entry's headers 
Expires, Last-Modified etc.). According to the documentation, these 
headers are
added in order to give client an ability to calculate object's freshness 
HTCP response does not provide such information explicitly. On the other 
hand, I
have not found any strict requirements of what HTTP headers HTCP reply 

Would the "effective" Last-Modified information help HTCP client to 
object's freshness? It looks that some more information in this case is 
that lack of it.


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