feat(cache): added CacheManager protocol

cache-manager.js

@@ -0,0 +1,38 @@
+'use strict'
+
+const duck = require('protoduck')
+
+// CacheManager
+//
+// This protocol defines the interface for a make-fetch-happen-compatible
+// cache implementation. Anything that implements this may be passed in as
+// make-fetch-happen's opts.cacheManager
+//
+// docs: https://developer.mozilla.org/en-US/docs/Web/API/Cache
+//
+// To implement this protocol, call it on a class and write the impls:
+//
+// const CacheManager = require('make-fetch-happen/cache-manager')
+// class MyCache {
+//   constructor (opts) { ... }
+// }
+//
+// CacheManager.impl(MyCache, {
+//   match (req) { ...get response... }, // -> fetch.Response
+//   put (req, res) { ...insert into cache... }, // -> fetch.Response
+//   delete (req) { ...remove from cache... } // -> Boolean
+// })
+//
+module.exports = duck.define(['req', 'res'], {
+  // Returns a Promise that resolves to the response associated with the first
+  // matching request in the Cache object.
+  match: ['req'],
+
+  // Takes both a request and its response and adds it to the given cache.
+  put: ['req', 'res'],
+
+  // Finds the Cache entry whose key is the request, and if found, deletes the
+  // Cache entry and returns a Promise that resolves to true. If no Cache entry
+  // is found, it returns false.
+  delete: ['req']
+})

cache.js

@@ -1,6 +1,7 @@
 'use strict'
 
 const cacache = require('cacache')
+const CacheManager = require('./cache-manager')
 const fetch = require('node-fetch')
 const fs = require('fs')
 const pipe = require('mississippi').pipe
@@ -11,33 +12,17 @@ const url = require('url')
 
 const MAX_MEM_SIZE = 5 * 1024 * 1024 // 5MB
 
-function cacheKey (req) {
-  const parsed = url.parse(req.url)
-  return `make-fetch-happen:request-cache:${
-    url.format({
-      protocol: parsed.protocol,
-      slashes: parsed.slashes,
-      host: parsed.host,
-      hostname: parsed.hostname,
-      pathname: parsed.pathname
-    })
-  }`
-}
-
-// This is a cacache-based implementation of the Cache standard,
-// using node-fetch.
-// docs: https://developer.mozilla.org/en-US/docs/Web/API/Cache
-//
-module.exports = class Cache {
+class Cacache {
   constructor (path, opts) {
     this._path = path
     this._uid = opts && opts.uid
     this._gid = opts && opts.gid
     this.Promise = (opts && opts.Promise) || Promise
   }
+}
+module.exports = Cacache
 
-  // Returns a Promise that resolves to the response associated with the first
-  // matching request in the Cache object.
+CacheManager.impl(Cacache, {
   match (req, opts) {
     const key = cacheKey(req)
     return cacache.get.info(this._path, key).then(info => {
@@ -110,9 +95,7 @@ module.exports = class Cache {
         })
       }
     })
-  }
-
-  // Takes both a request and its response and adds it to the given cache.
+  },
   put (req, response, opts) {
     const size = response.headers.get('content-length')
     const fitInMemory = !!size && size < MAX_MEM_SIZE
@@ -196,19 +179,15 @@ module.exports = class Cache {
       })
     }), err => err && newBody.emit('error', err))
     return response
-  }
-
-  // Finds the Cache entry whose key is the request, and if found, deletes the
-  // Cache entry and returns a Promise that resolves to true. If no Cache entry
-  // is found, it returns false.
+  },
   'delete' (req) {
     return cacache.rm.entry(
       this._path,
       cacheKey(req)
     // TODO - true/false
     ).then(() => false)
   }
-}
+})
 
 function matchDetails (req, cached) {
   const reqUrl = url.parse(req.url)
@@ -243,6 +222,19 @@ function matchDetails (req, cached) {
   return url.format(reqUrl) === url.format(cacheUrl)
 }
 
+function cacheKey (req) {
+  const parsed = url.parse(req.url)
+  return `make-fetch-happen:request-cache:${
+    url.format({
+      protocol: parsed.protocol,
+      slashes: parsed.slashes,
+      host: parsed.host,
+      hostname: parsed.hostname,
+      pathname: parsed.pathname
+    })
+  }`
+}
+
 function addCacheHeaders (resHeaders, path, key, hash, time) {
   resHeaders.set('X-Local-Cache', path)
   resHeaders.set('X-Local-Cache-Key', key)

package.json

@@ -38,13 +38,14 @@
   "dependencies": {
     "agentkeepalive": "^3.1.0",
     "cacache": "^7.0.3",
+    "http-cache-semantics": "^3.7.3",
     "http-proxy-agent": "^1.0.0",
     "https-proxy-agent": "^1.0.0",
-    "http-cache-semantics": "^3.7.3",
     "lru-cache": "^4.0.2",
     "mississippi": "^1.2.0",
     "node-fetch": "2.0.0-alpha.3",
     "promise-retry": "^1.1.1",
+    "protoduck": "^4.0.0",
     "socks-proxy-agent": "^2.0.0",
     "ssri": "^4.0.0"
   },