Does Varnish support Dependency Graph Cache Invalidation?

Question

Consider (the hypothetical ) case in which a page is cached which contains blogsposts which in turn contains comments. Now 1 comment changes. This means the cache for the blogpost has to be invalidated and (transitively) the cache for the page has to be invalidated.

In other words: items relate to eachother in a way that can be described as a Dependency Graph (which is a Directed Acyclic Graph )

Does Varnish support this type of Cache invalidation? If not, any other implementation, research, etc. that partially covers this?

Answer 1

There's no support for exactly what you are asking for but as a workaround you can put tags in your headers as to what comments they are dependent on. For example sending a:

x-depend-comments: 2578 2579 2580

And then at an update of a comment you can send a ban request as:

ban obj.http.x-depend-comments ~ “\D2578\D”