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

[Eduard Bagdasaryan]

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, 
e->lastModified());
 >
 > 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 
(Age,
Expires, Last-Modified etc.). According to the documentation, these 
headers are
added in order to give client an ability to calculate object's freshness 
itself:
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 
should
contain.

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


Eduard.