invalidating a set of entries

Venkatesh KS venkatesh.ks at
Fri Oct 5 06:34:31 UTC 2007

option 2 has a draw back that the invalid contents stay in the cache until
its time for ejection. And worst part is that
valid contents may keep getting ejected. For instance if the TTL values for
these invalid content is very high then the cache
does take a hit.

On 10/5/07, Dustin Sallings <dustin at> wrote:
> On Oct 4, 2007, at 2:36 , Venkatesh KS wrote:
> 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
> fail.
> 3. Write a regex engine (or a tag feature) which will go an invalidate all
> the entries matching a prefix or a tag.
> 2 is common, but the tag invalidation is closer to #3 than #1 (as I'm
> inferring from your description of #1).
> --
> Dustin Sallings
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