Invalidate cached URL

[shaunchurch]

I'd like to be able invalidate an API route / method in the cache.

I have a cached response from /api/route. When I take some action in my app which updates the data on the server, I know that the previous response from /api/route is now invalid, and I need to ensure next time I call that route a network call is made to get the new data.

I'm currently working around this by calling the route with Cache-Control: no-cache set, which seems to work to force a network request and then caches the new response next time it's called without no-cache, but obviously this is not ideal, causing network activity which might never be required (or might then be again invalidated by taking action before /api/route is called again).

I'm using OKHttp as a client in retrofit. See: http://stackoverflow.com/questions/23782531/how-to-invalidate-force-update-of-cache-route-at-next-request-with-retrofit-and

[swankjesse]

Yup, we should offer this. Not sure what the API will look like yet.

[swankjesse]

We probably need a mechanism to enumerate the cache.

[andrejvanderzee]

Facing exactly the same issue here. I have to force the URL not to be cached at all with Cache-Control: no-store. Is this work in progress? :)

[andrejvanderzee]

Actually, it looks like Cache-Control: no-store in the request header is not implemented.

Quote from RFC: "If sent in a request, a cache MUST NOT store any part of either this request or any response to it."

Source: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.2

[swankjesse]

@andrejvanderzee we fixed that in 2.1.

[andrejvanderzee]

Yes thanks confirmed, it is working in 2.1 :)

The milestone for invalidating cached URLs changed to 2.2. Will this be in 2014?

[swankjesse]

@andrejvanderzee invaliding a specific URL is pretty easy, but what I think most developers will want is a mechanism to invalidate a full URL pattern, like /account/*. What's your preference?

[andrejvanderzee]

At this moment I need a specific URL path. For example, suppose I open a screen with text messages with my user ID with the following URL:

@get(/messages/user/{userId}")
Messages getMessages(@path("userId") int userId);

Then I post a message, leave the screen and come back before Cache-Control expires. In that case, I will be served the cache and my own message is not included.

One awkward point is indeed that I have to reconstruct the URL with the user id myself. It would be nice to have an easy way to re-construct the URL from the annotated getMessages(), providing just the userId. It is awkward to keep the syntax of the URL in two places.

At this moment I cannot see any use for regular expressions. But I am sure there will be occasions!

[JakeWharton]

It would be nice to have an easy way to re-construct the URL from the annotated getMessages(), providing just the userId

Note that this is not OkHttp's problem. It only knows URLs.

[andrejvanderzee]

Yes indeed, its Retrofit.

Nevertheless, invalidating exact URLs would be a good solution.

[niqo01]

what I think most developers will want is a mechanism to invalidate a full URL pattern, like /account/*

We are interested by URL pattern invalidation. I think pagination might be a good example where you want invalidate all page URLs at once.
For example if an user is searching and joining individual events (/events/1), it would be nice to invalidate its own events list (/users/1/events?page=1, /users/1/events?page=2). with an invalidation pattern like /users/1/events*

[alican]

Hello,

is invalidating a specific cached URL possible now?

[swankjesse]

@alican yep. Use the iterator to iterate the URLs in the cache, then call remove() when you see a URL you don’t want anymore.

[alican]

Thank you Jesse for your answer :)
Have you an example code how to do this with retrofit?
I looked in the javadocs and didint see how do get the URLs from inside an android activity.

[alenz316]

@swankjesse or @niqo01 Do either of you have a gist of how to do URL pattern invalidation for cache eviction? Like suggested in the previous comment.

[Sternbach-Software]

For a code example, see https://stackoverflow.com/a/68012702/12528345.