feat(xen-api): coalesce connect calls

@xen-orchestra/babel-config/index.js

@@ -46,6 +46,12 @@ const getConfig = (key, ...args) => {
     : config
 }
 
+// some plugins must be used in a specific order
+const pluginsOrder = [
+  '@babel/plugin-proposal-decorators',
+  '@babel/plugin-proposal-class-properties',
+]
+
 module.exports = function(pkg, plugins, presets) {
   plugins === undefined && (plugins = {})
   presets === undefined && (presets = {})
@@ -61,7 +67,13 @@ module.exports = function(pkg, plugins, presets) {
   return {
     comments: !__PROD__,
     ignore: __TEST__ ? undefined : [/\.spec\.js$/],
-    plugins: Object.keys(plugins).map(plugin => [plugin, plugins[plugin]]),
+    plugins: Object.keys(plugins)
+      .map(plugin => [plugin, plugins[plugin]])
+      .sort(([a], [b]) => {
+        const oA = pluginsOrder.indexOf(a)
+        const oB = pluginsOrder.indexOf(b)
+        return oA !== -1 && oB !== -1 ? oA - oB : a < b ? -1 : 1
+      }),
     presets: Object.keys(presets).map(preset => [preset, presets[preset]]),
   }
 }

packages/xen-api/package.json

@@ -54,6 +54,7 @@
   "devDependencies": {
     "@babel/cli": "^7.0.0",
     "@babel/core": "^7.0.0",
+    "@babel/plugin-proposal-class-properties": "^7.3.4",
     "@babel/plugin-proposal-decorators": "^7.0.0",
     "@babel/plugin-proposal-nullish-coalescing-operator": "^7.2.0",
     "@babel/plugin-proposal-optional-chaining": "^7.2.0",

packages/xen-api/src/_coalesceCalls.js

@@ -0,0 +1,15 @@
+// decorates fn so that more than one concurrent calls will be coalesced
+export default function coalesceCalls(fn) {
+  let promise
+  const clean = () => {
+    promise = undefined
+  }
+  return function() {
+    if (promise !== undefined) {
+      return promise
+    }
+    promise = fn.apply(this, arguments)
+    promise.then(clean, clean)
+    return promise
+  }
+}

packages/xen-api/src/_coalesceCalls.spec.js

@@ -0,0 +1,26 @@
+/* eslint-env jest */
+
+import pDefer from 'promise-toolbox/defer'
+
+import coalesceCalls from './_coalesceCalls'
+
+describe('coalesceCalls', () => {
+  it('decorates an async function', async () => {
+    const fn = coalesceCalls(promise => promise)
+
+    const defer1 = pDefer()
+    const promise1 = fn(defer1.promise)
+    const defer2 = pDefer()
+    const promise2 = fn(defer2.promise)
+
+    defer1.resolve('foo')
+    expect(await promise1).toBe('foo')
+    expect(await promise2).toBe('foo')
+
+    const defer3 = pDefer()
+    const promise3 = fn(defer3.promise)
+
+    defer3.resolve('bar')
+    expect(await promise3).toBe('bar')
+  })
+})

packages/xen-api/src/index.js

@@ -26,6 +26,7 @@ import {
 } from 'promise-toolbox'
 
 import autoTransport from './transports/auto'
+import coalesceCalls from './_coalesceCalls'
 import debug from './_debug'
 import getTaskResult from './_getTaskResult'
 import isGetAllRecordsMethod from './_isGetAllRecordsMethod'
@@ -201,6 +202,7 @@ export class Xapi extends EventEmitter {
     return id ? (id === CONNECTING ? CONNECTING : CONNECTED) : DISCONNECTED
   }
 
+  connect = coalesceCalls(this.connect)
   async connect() {
     const { status } = this
 

yarn.lock

@@ -256,6 +256,14 @@
     "@babel/helper-remap-async-to-generator" "^7.1.0"
     "@babel/plugin-syntax-async-generators" "^7.2.0"
 
+"@babel/plugin-proposal-class-properties@^7.3.4":
+  version "7.4.0"
+  resolved "https://registry.yarnpkg.com/@babel/plugin-proposal-class-properties/-/plugin-proposal-class-properties-7.4.0.tgz#d70db61a2f1fd79de927eea91f6411c964e084b8"
+  integrity sha512-t2ECPNOXsIeK1JxJNKmgbzQtoG27KIlVE61vTqX0DKR9E9sZlVVxWUtEW9D5FlZ8b8j7SBNCHY47GgPKCKlpPg==
+  dependencies:
+    "@babel/helper-create-class-features-plugin" "^7.4.0"
+    "@babel/helper-plugin-utils" "^7.0.0"
+
 "@babel/plugin-proposal-decorators@^7.0.0", "@babel/plugin-proposal-decorators@^7.1.6":
   version "7.4.0"
   resolved "https://registry.yarnpkg.com/@babel/plugin-proposal-decorators/-/plugin-proposal-decorators-7.4.0.tgz#8e1bfd83efa54a5f662033afcc2b8e701f4bb3a9"