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import * as express from 'express'
import * as AsyncLock from 'async-lock'
import { parseDurationToMs } from '../helpers/core-utils'
import { Redis } from '../lib/redis'
import { logger } from '../helpers/logger'
const lock = new AsyncLock({ timeout: 5000 })
function cacheRoute (lifetimeArg: string | number) {
const lifetime = parseDurationToMs(lifetimeArg)
return async function (req: express.Request, res: express.Response, next: express.NextFunction) {
const redisKey = Redis.Instance.generateCachedRouteKey(req)
try {
await lock.acquire(redisKey, async (done) => {
const cached = await Redis.Instance.getCachedRoute(req)
// Not cached
if (!cached) {
logger.debug('No cached results for route %s.', req.originalUrl)
const sendSave = res.send.bind(res)
const redirectSave = res.redirect.bind(res)
res.send = (body) => {
if (res.statusCode >= 200 && res.statusCode < 400) {
const contentType = res.get('content-type')
Redis.Instance.setCachedRoute(req, body, lifetime, contentType, res.statusCode)
.then(() => done())
.catch(err => {
logger.error('Cannot cache route.', { err })
return done(err)
})
} else {
done()
}
return sendSave(body)
}
res.redirect = url => {
done()
return redirectSave(url)
}
return next()
}
if (cached.contentType) res.set('content-type', cached.contentType)
if (cached.statusCode) {
const statusCode = parseInt(cached.statusCode, 10)
if (!isNaN(statusCode)) res.status(statusCode)
}
logger.debug('Use cached result for %s.', req.originalUrl)
res.send(cached.body).end()
return done()
})
} catch (err) {
logger.error('Cannot serve cached route.', { err })
return next()
}
}
}
// ---------------------------------------------------------------------------
export {
cacheRoute
}
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