feat(gatsby): provide a mechanism for plugins to use a named cache instance

packages/gatsby/src/utils/__tests__/get-cache.js

@@ -0,0 +1,21 @@
+const getCache = require(`../get-cache`)
+
+const CACHE_KEY = `__test__`
+
+test(`it returns a new cache instance`, () => {
+  const cache = getCache(CACHE_KEY)
+
+  expect(cache.get).toEqual(expect.any(Function))
+  expect(cache.set).toEqual(expect.any(Function))
+})
+
+test(`it retrieves already created cache instance`, async () => {
+  const key = `some-value`
+  const value = [`a`, `b`, `c`]
+  const cache = getCache(CACHE_KEY)
+  await cache.set(key, value)
+
+  const other = getCache(CACHE_KEY)
+
+  expect(await other.get(key)).toEqual(value)
+})

packages/gatsby/src/utils/api-runner-node.js

@@ -4,13 +4,11 @@ const _ = require(`lodash`)
 
 const tracer = require(`opentracing`).globalTracer()
 const reporter = require(`gatsby-cli/lib/reporter`)
-const Cache = require(`./cache`)
+const getCache = require(`./get-cache`)
 const apiList = require(`./api-node-docs`)
 const createNodeId = require(`./create-node-id`)
 const createContentDigest = require(`./create-content-digest`)
 
-let caches = new Map()
-
 // Bind action creators per plugin so we can auto-add
 // metadata to actions they create.
 const boundPluginActionCreators = {}
@@ -94,11 +92,7 @@ const runAPI = (plugin, api, args) => {
 
     const tracing = initAPICallTracing(pluginSpan)
 
-    let cache = caches.get(plugin.name)
-    if (!cache) {
-      cache = new Cache({ name: plugin.name }).init()
-      caches.set(plugin.name, cache)
-    }
+    const cache = getCache(plugin.name)
 
     const apiCallArgs = [
       {
@@ -109,6 +103,7 @@ const runAPI = (plugin, api, args) => {
         loadNodeContent,
         store,
         emitter,
+        getCache,
         getNodes,
         getNode,
         getNodesByType,

packages/gatsby/src/utils/get-cache.js

@@ -0,0 +1,12 @@
+const Cache = require(`./cache`)
+
+let caches = new Map()
+
+module.exports = function getCache(name) {
+  let cache = caches.get(name)
+  if (!cache) {
+    cache = new Cache({ name }).init()
+    caches.set(name, cache)
+  }
+  return cache
+}