ioredis-cache

Compact redis cache using ioredis.

Features

- Store/retrieve/expire cache
- Compatible with redis incr, hincrby,...
- Cache multiple objects at once
- Delete caches by key pattern
- Take advantage of the redis hash map for memory efficiency

Installation

``
npm install ioredis-cache
`

`
yarn add ioredis-cache
`

Usage

`javascript
const Redis = require("ioredis")
const Cache = require("ioredis-cache")
const cache = new Cache(new Redis())

const value = await cache.cache("key", async () => ({ foo: "bar" }))
`

Notes

Depends on your case, you may want to disconnect redis after using:
`
cache.redis.quit()
`

APIs

#constructor

#cache

#getCache

#setCache

#manyCache

#getManyCache

#setManyCache

#deleteCache

#deletePattern

#acquire

#hashCache

#getHashCache

#setHashCache

#hashManyCache

#getHashManyCache

#setHashManyCache

#deleteHashCache

#hashAcquire




$3


constructor(args: Redis | CacheOptions)

You can initialize the cache from an ioredis object or with options.

`typescript
interface CacheOptions {
redis: object | Redis
parser: Parser
}

interface Parser { // Parse/unparse object when store in redis. Default is JSON
parse: (text: string) => any
stringify: (value: any) => string
}
`

$3


cache(key: string, callback: async (key: string) => any, ttl?: number): Promise

Get the cached value of the key from redis. If the key does not exist, get the value from the callback, store it in redis and return the value.

If the callback return undefined, it will not be cached. null is cached normally.

If ttl is set, the key will expire after ttl second(s).

`javascript
const getPost = (id) =>
cache(post-${id}, () => db.Post.getPostWithId(id), 60 * 60)
`

$3


getCache(key: string): Promise

Get the cached value of the key from redis. If the key does not exist, return undefined.

$3


setCache(key: string, value: any, ttl?: number)

Store the value to the cache key.

If ttl is set, the key will expire after ttl second(s).

$3


manyCache(keys: string[], callback: async (ids: string[]) => { [id: string]: any } | any[], prefix?: string, ttl?: number)

Get cached values for a list of keys from redis. The uncached keys will be passed to the callback to get the corresponding values. These values will be stored in redis. Returns combined array of both cached and uncached values.

If prefix is set, it will be preend to the key when get/set in redis. (The keys which are passed to the callback still don't have the prefix)

This is useful if some cached ids were invalidated, you can recache multiple values at once. For example:

`javascript
// invalidate cache of the changed post
db.Post.onChange(post => cache.deleteCache(post-${post.id}))
// this function queries all posts that are uncached at once
const getPosts = (ids) =>
manyCache(ids, async (uncachedIds) => {
const posts = await db.Post.queryAllPostsWithIds(uncachedIds)
return posts.reduce((map, post) => Object.assign(map, { [post.id]: post }), {})
}, prefix: 'post-', 60 * 60)
`

$3


getManyCache(keys: string[]): Promise

Return cached values for a list of keys from redis. If a key does not exist, the value will be undefined.

$3


setManyCache(keys: string[], ttl?: number)

Store the values with the corresponding keys in redis.

If ttl is set, the keys will expire after ttl second(s).

$3


deleteCache(...keys: string[]): Promise

Delete the cached keys from redis and return the deleted number

$3

deletePattern(pattern: string, batch: number = 100)

Scan all keys and delete the keys that matched the pattern:

`javascript
deletePattern('post:*')
`
Remove all cached keys start with "post:*".

$3


acquire(key: string, amount: number, fn: (current: number) => any, float: boolean = false)

Increase the value of key by amount and pass it to fn function. If fn raises any exception, decrease the value of the key by amount.

By default, amount is treate as an integer. Set float = true if amount is a float.

$3


hashCache(key: string, id: string, callback: () => any): Promise

Get the cached id of the key from redis. If the id or key does not exist, get the value from the callback, store it in redis and return the value.

This function is similar to #cache, but stores value in redis hash for better memory effeciency. You can remove the hash by simply deleting the cache key. This is better than using #deletePattern if there are a lot of keys to be deleted. The only downside is you can't set the ttl for each id but only for the hash.

$3


getHashCache(key: string, id: string): Promise

Return the cached id of the key from redis. If the id / key does not exist, return undefined.

$3


setHashCache(key: string, value: any)

Store the value to the id of key

$3

hashManyCache(key: string, ids: string[], callback: (ids: string[]) => { [id: string]: any } | any[]): Promise

Get cached values for the id array of the key from redis. The uncached ids will be passed to the callback to get the corresponding values. These values will be stored in redis. Returns a combined array of both cached and uncached values.

It is similar to #manyCache, but use redis hash to store data.

`javascript
// invalidate cache of the changed post
db.Post.onChange(post => cache.deleteHashCache('post', post.id))
// this function queries all posts that are uncached at once
const getPosts = (ids) =>
hashManyCache('post', ids, async (uncachedIds) => {
const posts = await db.Post.queryAllPostsWithIds(uncachedIds)
return posts.reduce((map, post) => Object.assign(map, { [post.id]: post }), {})
})
`

$3


getHashManyCache(key: string, ids: string[]): Promise

Return cached values for the id array of the key from redis. If the id / key does not exist, the value will be undefined.

$3


setHashManyCache(key: string, valueMap: { [id: string]: any })

Store the values with the corresponding ids of the key in redis

$3

deleteHashCache(key: string, ...ids: string[]): Promise

Delete the cached ids of the key from redis and return the deleted number

$3

hashAcquire(key: string, id: string, amount: number, fn: (current: number) => any, float: boolean = false)

Increase the value of id in key by amount and pass it to fn function. If fn raises any exception, decrease the value of id in key by amount.

By default, amount is treated as an integer. Set float = true if amount is a float.

Run tests

Make sure the redis is running at localhost:6379

Run the following command:

`
yarn test
``