Create factory for CacheClient #4558
Description
Problem
Currently, we pass the redisClient to our CacheService, which may be undefined. Based on this value the CacheService decides if it needs to initialize LRUCache or RedisCache, however passing redisClient as undefined breaks the Interface segregation principle.
class CacheService implements ICacheClient {
//.....
public constructor(
logger: Logger,
register: Registry = new Registry(),
reservedKeys: Set<string> = new Set(),
redisClient?: RedisClientType,
) {
this.logger = logger;
this.register = register;
this.internalCache = new LocalLRUCache(logger.child({ name: 'localLRUCache' }), register, reservedKeys);
this.sharedCache = this.internalCache;
this.isSharedCacheEnabled = !ConfigService.get('TEST') && redisClient !== undefined;
this.shouldMultiSet = ConfigService.get('MULTI_SET');
if (this.isSharedCacheEnabled) {
this.sharedCache = new RedisCache(logger.child({ name: 'redisCache' }), register, redisClient!);
}
//.......
}Solution
Create a factory class creating either LRUCache or RedisCache and pass them to CacheService
export class CacheFactory {
static create(redisClient?: RedisClientType): CacheClient {
return redisClient
? new RedisCache(redisClient)
: new LRUCache();
}
}
// In Relay
const cache = CacheFactory.create(this.redisClient);
new CacheService(cache, ...)Benefits
- Encapsulates cache selection logic
- Cache service does not deal with creating cache classes
- Easier to add new cache types
- Stick to the interface segregation principle