Auto revalidate when X-Vercel-Cache is STALE

[hazae41]

Let's suppose my endpoint has changing data that takes time to (re)generate.
I use stale-while-revalidate in Cache-Control so the Vercel Edge Cache returns its stale data while refreshing.

According to this doc GET /api/data will either respond with

• some stale data with X-Vercel-Cache set to STALE
• some fresh data with X-Vercel-Cache set to either MISS, HIT, REVALIDATED, BYPASS
• some static data with X-Vercel-Cache set to PRERENDER

The proposal is that if the response is stale (STALE), the SWR library will force revalidate every X seconds until it gets the latest fresh data (HIT).

This way, the client always gets some data to deal with, and it gets the latest fresh data when it's ready.

Here is how I see the config:

useSWR(..., {
  refreshStaleInterval: 5 // seconds to wait before each request
})

Is some sense, it behaves like refreshInterval excepts it stops itself when it gets fresh data.