ref
https://linear.app/tryghost/issue/ENG-902/add-an-optional-timeout-in-the-redis-cache-adapter-in-case-redis
- Added an optional timeout parameter to AdapterCacheRedis, so that the
`get(key)` method will return `null` after the timeout if it hasn't
received a response from Redis
- When load testing the `LinkRedirectRepository` with the Redis cache
enabled on staging, we noticed that for some reason Redis stopped
responding to commands for ~30 seconds.
- The `LinkRedirectRepository` was waiting for the Redis cache to
respond and resulted in a drastic increase in response times for link
redirects
- This change will allow us to set a timeout on the `get(key)` method,
so that if Redis doesn't respond within the timeout, the method will
return `null` as if it were a cache miss.
- Then the `LinkRedirectRepository` will fall back to the database and
return the link redirect from the database instead of waiting
indefinitely for Redis to respond
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