express cache

Cache Middleware for Express. The default is LRU-based cache



how to use

$3

``ecmascript 6
// server.js
import { getCacheMiddleware } from 'express-cache'
//...
app.use(getCacheMiddleware())
`

$3

`ecmascript 6
// server.js
import { getCacheMiddleware } from 'express-cache'

// logging during cache operation
function logging(req, res, next, cached) {
debug(req info: ${req.url} ${req.method})
debug(cache info: ${key} ${value})
}

app.use(getCacheMiddleware({ hook: logging}))
`

$3


ref. https://github.com/isaacs/node-lru-cache
`ecmascript 6
// server.js
import { getCacheMiddleware } from 'express-cache'
//...
app.use(getCacheMiddleware({
configLRU : {
max: 1,
maxAge: 100,
length: function(value, key) {
//...
}
}
}))
//

`


config cachePolicy

routeList 존재하면, 정확히 routeList 명시된 것에만 적용, 없으면 전체 적용
exceptList 존재하면, exceptList 제외

routeList If present, applies exactly to the routeList specified;
exceptList Except, exceptList Except

`ecmascript 6
// server.js
import { getCacheMiddleware, strategy } from 'express-cache'
//...
app.use(getCacheMiddleware({
cachePolicy: {
routeList: [ {
id: 'someUrl',
check: (req) => {
return true // or false
},
}],
exceptList: [{
id: 'someUrl',
check: (req) => {
return true // or false
},
}],
}
}))
`

inject LRU


cluster 등 LRU 공유 필요 시 외부에서 주입
`ecmascript 6
// server.js
import { getCacheMiddleware } from 'express-cache'

//cluster, etc. If LRU sharing is required,
app.use(getCacheMiddleware({
LRU: myLRU
}))
`

export LRU Cache


`ecmascript 6
import { getLRU } from 'express-cache'

getLRU().resert()
`

default value


`typescript
const sec = 1000
const minute = 1000 * 60
const hour = minute * 60
const halfDay = hour * 12
const day = hour * 24

enum Time {
sec, minute, hour, halfDay, day,
}

const defaultLRUConfig = {
max: 1000,
maxAge: 5 * Time.minute,
// @ts-ignore
length: function (value = '') {
// @ts-ignore
const stringLength = value => value.length / 10
// @ts-ignore
const NumberLength = value => value.toString().length

const strOrNumberLength = (value: string | number) => {
if (is(String, value)) {
return stringLength(value)
}
if (is(Number, value)) {
return NumberLength(value)
}
return 1 // other
}
if (is(Object, value)) {
Object.values(value).map(strOrNumberLength).reduce((result, current) => {
return result + current
}, 0)
}
return strOrNumberLength(value)
},
}

const generateKey: generateKeyFunc = function (req: express.Request) {
return ${req.originalUrl}-${req.method}
}

const isErrorFunc: isError = (_, res) => {
return res.statusCode > 400
}

const resFunc: resFunc = (res: express.Response, cached) => {
const reqUrl = path(['req', 'url'], res)
log(cached send reqUrl : ${reqUrl})
const {body, statusCode = 200, headersSent, headers} = cached
if (headersSent && headers) {
res.set(headers)
}
res.status(statusCode).send(body)
}

const defaultConfigCache = {
configLRU: defaultLRUConfig,
generateKey,
resFunc,
isError: isErrorFunc,
}


``

ref

https://github.com/isaacs/node-lru-cache