cache-service-lib v5.2.2

Cache service lib

Presenting a reusable cache library to Node.Js. This library uses well defined cache solutions such as redis and node-cache to deliver scalable and reusable cache services.

An abstraction layer is provided through Adapter and Strategy design patterns, allowing also to simplify multilevel cache solutions.

Simple usage

import { createCacheService } from 'cache-service-lib';
import { RedisCacheStrategy } from 'cache-service-lib/lib/strategies/RedisCacheStrategy';

const cacheService = createCacheService();
cacheService.registerStrategy(
  'redis',
  new RedisCacheStrategy({
    host: 'localhost',
    port: 6379,
  })
);

cacheService.set('key', 'value', 30); // Will expire cache entry in 30s

Multilevel cache Usage with sync scenarios

import { createCacheService } from 'cache-service-lib';
import { RedisCacheStrategy } from 'cache-service-lib/lib/strategies/RedisCacheStrategy';
import { MemCacheStrategy } from 'cache-service-lib/lib/strategies/MemCacheStrategy';

const cacheService = createCacheService();
cacheService.registerStrategy('mem', new MemCacheStrategy());
cacheService.registerStrategy(
  'redis',
  new RedisCacheStrategy({
    host: 'localhost',
    port: 6379,
  })
);
cacheService.chooseStrategy('redis').set('key', 'value', 30); // Will expire cache entry in 30s

Multilevel cache Usage with async scenarios

In async scenarios, in order to ensure the correct strategy at each call is recommended to pass the parameter *strategyStorage:'async'* to createCacheService.

This parameter enables the usage of the async_hooks Node.Js api to store and retrieve the current strategy. Please make sure the client node version supports this feature.

import { createCacheService } from 'cache-service-lib';
import { RedisCacheStrategy } from 'cache-service-lib/lib/strategies/RedisCacheStrategy';
import { MemCacheStrategy } from 'cache-service-lib/lib/strategies/MemCacheStrategy';

const cacheService = createCacheService({ strategyStorage: 'async' });
cacheService.registerStrategy('mem', new MemCacheStrategy());
cacheService.registerStrategy(
  'redis',
  new RedisCacheStrategy({
    host: 'localhost',
    port: 6379,
  })
);
cacheService.chooseStrategy('redis').set('key', 'value', 30); // Will expire cache entry in 30s

Notes

The first strategy registered will be automatically marked as the currentStrategy.

Methods available

• registerStrategy(name: string, strategy: CacheStrategy): void
• chooseStrategy(name: string) : void
• listStrategies() : Array\<string>
• call\<T>(fn: () => Promise\<T>, key: string, expiresIn?: number) : Promise\<T>
• get\<T>(key: string): Promise<T | undefined>;
• set(key: string, value: unknown, expiresIn?: number): Promise\<void>;
• del(key: string): Promise\<void>;
• delByPrefix(prefix: string): Promise\<void>;
• flush(): Promise\<void>;

Plugins

There are some modifiers available to enable functionalities on top of the default CacheService. This plugins can be used as decorators of CacheServiceProtocols.

AutoRefreshCache plugin

Enable auto refresh functionality at call function.

• call\<T>(fn: () => Promise\<T>, key: string, refreshsIn?: number) : Promise\<T>

import { createCacheService, MemcacheStrategy, plugins } from 'cache-service-lib';
const cacheService = plugins.autoRefresh(createCacheService());
cacheService.registerStrategy('mem', new MemCacheStrategy());

const fn = async () => ['value'];
cacheService.call(fn, 'key', 30); // Will autorefresh cache entry every 30s

Conflicting set operations will cancel auto refresh schedules.

Developing notes

Commands to create test dynamodb table:

aws dynamodb --region us-east-1 --endpoint-url http://localhost:8000 create-table --table-name table-1 \
--attribute-definitions AttributeName=kind,AttributeType=S AttributeName=key,AttributeType=S --key-schema AttributeName=kind,KeyType=HASH AttributeName=key,KeyType=RANGE \
--provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5

aws dynamodb --region us-east-1 --endpoint-url http://localhost:8000 update-time-to-live --table-name table-1 --time-to-live-specification "Enabled=true, AttributeName=ttl"