Epoch Invalidation

Invalidating cached data is notoriously difficult. Most libraries struggle with performance when deleting many keys at once.

The O(1) Solution

@express-route-cache uses Epoch Versioning. Every route pattern (e.g., /users) has a version number (an "epoch") stored in the cache.

• Storage: When caching /users/123, we include the current epoch of /users in the key.
• Invalidation: To invalidate all /users/* routes, we simply increment the epoch of /users.
• Result: All existing cache keys for /users instantly become "ghosts"—they still exist in the database but will never be queried again because the application is now looking for a higher epoch version.

Usage

Manual Invalidation

// Increment epoch for /users
await cache.invalidateRoute('/users');

Middleware Invalidation

app.post('/users', cache.invalidate('/users'), createUser);

Auto Invalidation

Set autoInvalidate: true to automatically increment epochs for matching patterns when a successful POST, PUT, or DELETE request occurs on a route.

const cache = createCache({ autoInvalidate: true });