ensure lock is held while setting cache

[n1ywb]

lock_and_cache_js/index.js

Line 366 in 05258a8

let v = await this._cache.set(key, this._cacheSetTransform(value), {

If you needed a really strong guarantee that the lock was in fact held while setting a redis cache value and the lock and cache redis servers were one and the same then you could use Lua to query the lock and set the cache value atomically.

I suppose at that point you may as well just store the lock and cache values under the same key

[emk]

I believe that this is ruled out by the desire to support separate lock and cache servers in normal operation.

[n1ywb]

If that's the case then it should probably use distributed transactions to ensure consistency.