One caching pattern I find myself doing a lot on Redis is where multiple clients try to access the same cached value, but if it doesn't exist only one is allowe

One caching pattern I find myself doing a lot on Redis is where multiple clients try to access the same cached value, but if it doesn't exist only one is allowed to revalidate it, all other clients wait until it's revalidated and get notified with the new value. Currently for the clients it involves: 1. subscribe for updates on the key you're trying to retrieve 2. retrieve cached value or set a lock 3. if lock acquired, unsubscribe, then fetch value 4. set the result in a key and publish event with the value I wish there was a command that does: retrieve value of a key, if it doesn't exist lock the key and notify me with an id, if it's locked subscribe for the next update on the key. With a second command that acknowledges the lock with a new value Now I know this can be implemented and I've done so multiple times. It's just that it's tricky to get right and consistent.