feat(cache): add support for expiration

lib/hydrate.js

@@ -39,11 +39,12 @@ function parseHeader (str) {
 }
 
 export default function hydrate (value) {
-  const xhr = value.body || {}
-  const headers = parseHeader(value.headers || {})
+  const data = value.data
+  const xhr = data.body || {}
+  const headers = parseHeader(data.headers || {})
 
   xhr.getAllResponseHeaders = function () {
-    return value.headers
+    return data.headers
   }
 
   xhr.getResponseHeader = function (header) {

lib/index.js

@@ -11,6 +11,7 @@ function cache (config = {}) {
   const store = config.store
   const key = config.key || cache.key
 
+  config.maxAge = config.maxAge || 0
   config.readCache = config.readCache || readCache
   config.serialize = config.serialize || serialize
 
@@ -43,7 +44,10 @@ function cache (config = {}) {
     const f = () => {
       return next()
         .then(res => {
-          return store.setItem(uuid, config.serialize(req, res))
+          return store.setItem(uuid, {
+            expires: config.maxAge === 0 ? 0 : Date.now() + config.maxAge,
+            data: config.serialize(req, res)
+          })
         })
     }
 

lib/read-cache.js

@@ -3,7 +3,7 @@ import hydrate from './hydrate'
 export default function (req, log) {
   return function (value) {
     return new Promise((resolve, reject) => {
-      if (!value) {
+      if (!value || !value.data) {
         log('cache-miss', req.url)
         const error = new Error()
 
@@ -12,6 +12,20 @@ export default function (req, log) {
         return reject(error)
       }
 
+      const { expires, data } = value
+
+      if (expires !== 0 && (expires < Date.now())) {
+        log('cache-stale', req.url)
+        const error = new Error()
+
+        error.reason = 'cache-stale'
+        error.message = 'Value is stale'
+        return reject(error)
+      }
+
+      // hydrate pseudo xhr from cached value
+      req.xhr = hydrate(data)
+
       // override request end callback
       req.callback = (err, res) => {
         log('cache-hit', req.url)
@@ -23,8 +37,6 @@ export default function (req, log) {
         resolve(res)
       }
 
-      // hydrate pseudo xhr from cached value
-      req.xhr = hydrate(value)
       req.emit('end')
     })
   }