Caching Warning

rubyonrails-talk
1

This might be considered a bug... but I thought I'd at least warn folks.

I'm using fragment caching and the host name is in the key of the fragment. The problem is that this is the host name used in the URL. So, if you have two or more ways to get to the same host, you will have multiple versions of the same cached object.

For example, if your domain is foo.com and your host is bar, then some users might use http://bar/rest/of/path and others might use Foo.com

In one case, bar is the host and is used in the key for the fragments and in other cases bar.foo.com is. This creates a problem when you try to invalid a cached entity. If you are using a sweeper and the user comes in as bar and updates a database record, you flush the cache entry with bar in the name but not the cache entry with bar.foo.com in the name. You still have the old fragment cached up and some of your lusers will hit it.

I'm not sure quiet yet how to fix this. I want to somehow modify the host in the request to be the fully qualified hostname and not the short hand version.

2

This might be considered a bug... but I thought I'd at least warn folks.

I'm using fragment caching and the host name is in the key of the fragment. The problem is that this is the host name used in the URL. So, if you have two or more ways to get to the same host, you will have multiple versions of the same cached object.

For example, if your domain is foo.com and your host is bar, then some users might usehttp://bar/rest/of/pathand others might usehttp://bar.foo.com/rest/of/path

In one case, bar is the host and is used in the key for the fragments and in other cases bar.foo.com is. This creates a problem when you try to invalid a cached entity. If you are using a sweeper and the user comes in as bar and updates a database record, you flush the cache entry with bar in the name but not the cache entry with bar.foo.com in the name. You still have the old fragment cached up and some of your lusers will hit it.

Sort of makes sense - you could easily have different subdomains be different user accounts or something like that.

I'm not sure quiet yet how to fix this. I want to somehow modify the host in the request to be the fully qualified hostname and not the short hand version.

apache/nginx rewrite rules can do this

Fred

3

Frederick Cheung wrote:

apache/nginx rewrite rules can do this

I'm worried about redirects. The server is behind a firewall. The browser thinks that foo.outside.com is different from foo. If I am authenticated to foo.outside.com and then foo happens to ask for authentication, the browser will ask me again instead of just sending what it already has.

I might be worried about nothing.

4

Frederick Cheung wrote:

> apache/nginx rewrite rules can do this

I'm worried about redirects. The server is behind a firewall. The browser thinks that foo.outside.com is different from foo. If I am authenticated to foo.outside.com and then foo happens to ask for authentication, the browser will ask me again instead of just sending what it already has.

in that case it may be simpler to just fiddle the HTTP_HOST variable

Fred