NullCache

NullCache is a cache backend that implements a standard caching interface but does not store any data. Reads always result in a cache miss, and writes are ignored. As a result, it provides a no-op cache layer that preserves API compatibility without affecting memory usage or performance characteristics.

In operation, get(key) returns None or a dedicated miss value; set(key, value, ttl) is a no-op; delete(key) and clear() perform no action. Some implementations may also treat contains/has(key) as always false. The interface remains usable by applications that rely on a consistent caching API, even though no data is actually cached.

Common use cases include disabling caching in development or test environments, providing a deterministic baseline for performance measurements, or serving as a default backend to simplify configuration when caching is optional. It also facilitates testing of cache-logic paths and error handling without introducing caching side effects.

Design notes: NullCache is an example of the Null Object design pattern. It is usually stateless or implemented as a singleton to avoid unnecessary allocations. While it avoids memory usage and reduces complexity in some deployments, it does not improve response times or reduce database load. Its use should be deliberate and clearly communicated to developers.

See also: Null Object Pattern; No-op cache; Dummy cache; Cache backends.