[GrowthBook provider] Auto refresh flags with a stale-while-revalidate strategy #148
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AAorris
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Jul 31, 2025
AAorris
reviewed
Jul 31, 2025
dferber90
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Aug 1, 2025
| if (!isStale) return; | ||
| _lastRefreshTimestamp = Date.now(); | ||
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| if (options.edgeConfig) { |
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As a next step: When Edge Config is active you should be able to always read Edge Config without any caching on your ned. The Edge Config client returns the same reference if the Edge Config has not changed, so you can skip any re-initialization then.
Our goal with Edge Config is to eliminate any need for TTL or time based caching. Doesn't need to happen in this pull request but would be nice as a north star for this adapter.
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Changes
Currently in the GrowthBook adapter, flags are fetched once at server startup, stored in-memory, and never refreshed.
This PR changes it so that every time a flag is evaluated, we check if the in-memory flag definitions are stale, and if so, refresh in the background from either Edge Config or the GrowthBook API (depending on which one the adapter is configured to use).
New adapter options / methods
There is a new adapter option
cacheTTLmsthat defaults to 1s in dev (for better DX) and 30s in prod, but can be overridden as needed.There is also a new adapater method
refresh()that can be called manually.Testing
I tested in a new Next.js app both with and without Edge Config and confirmed features refresh as expected.
Because of the stale-while-revalidate logic for both Edge Config and GrowthBook's built-in fetching, it takes at least 2 refreshes on dev to see any flag changes reflected.