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

[Eduard Bagdasaryan]

2016-08-21 15:58 GMT+03:00 Amos Jeffries <squid3 at treenet.co.nz>:

 > To change anything between those markers we have to do a full cache
 > versioning and up/down-grade compatibility dance.

Could you please clarify what versioning problems you are talking about?  It
seems that StoreEntry's STORE_META_STD fields are not used directly while
storing/restoring metainformation. I found only places where field-by-field
assignment is performed (e.g., InitStoreEntry::operator()), so making
StoreEntry::lastmod 'private' should not do any harm there.  So probably we
could mark with  "START OF ON-DISK STORE_META_STD TLV field" (or 
similar) the
StoreEntry::lastmod, which is now private.

 > lastModifiedDelta() returning -1 when the actual delta is any -N value
 > is wrong conceptually. A delta should be the actual difference value 
-N < 0 < +N.

Since we need and use only the positive outcome of this method inside
refreshStaleness(), probably rename it to ageWhenCached() (or similar)?
Returning '-1' would mean that it is impossible to calculate the age 
('lastmod'
is absent or greater than timestamp).


Eduard.