invalidating a set of entries

Venkatesh KS venkatesh.ks at
Thu Oct 4 09:36:37 UTC 2007


We have a requirement to invalidate a set of cache entries based on a prefix
(or a tag)

I thought of the following approaches

1. Tag each entry (as discussed in the other thread) with a gen count and
once we want to invalidate
incr the global gen count. While looking up, if the gen count of the entry
is less than the global gen count
for a given prefix (or tag) then return null.

2. Each key also has a gen count as a part of the key (for a given prefix or
a tag). When we want to invalidate
then bump up the gen count in the client. So all subsequent lookups will

3. Write a regex engine (or a tag feature) which will go an invalidate all
the entries matching a prefix or a tag.

Options 1 and 2 are easy to implement but the drawback is that because of
the way ejections work (LRU)
we may let these invalid content hang around and eject out valid content.

Any other way of handling this?

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