feat(singleton): support async create function

lib/core/singleton.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const assert = require('assert');
+const is = require('is-type-of');
 
 class Singleton {
   constructor(options = {}) {
@@ -16,25 +17,28 @@ class Singleton {
     this.options = options.app.config[this.name] || {};
   }
 
-  init() {
+  async init() {
     const options = this.options;
     assert(!(options.client && options.clients),
       `egg:singleton ${this.name} can not set options.client and options.clients both`);
 
     // alias app[name] as client, but still support createInstance method
     if (options.client) {
-      const client = this.createInstance(options.client);
+      const client = await this.createInstanceAsync(options.client);
       this.app[this.name] = client;
       assert(!client.createInstance, 'singleton instance should not have createInstance method');
+      assert(!client.createInstanceAsync, 'singleton instance should not have createInstanceAsync method');
       client.createInstance = this.createInstance.bind(this);
+      client.createInstanceAsync = this.createInstanceAsync.bind(this);
       return;
     }
 
     // multi clent, use app[name].getInstance(id)
     if (options.clients) {
-      for (const id in options.clients) {
-        this.clients.set(id, this.createInstance(options.clients[id]));
-      }
+      await Promise.all(Object.keys(options.clients).map(id => {
+        return this.createInstanceAsync(options.clients[id])
+          .then(client => this.clients.set(id, client));
+      }));
       this.app[this.name] = this;
       return;
     }
@@ -48,10 +52,23 @@ class Singleton {
   }
 
   createInstance(config) {
+    // async creator only support createInstanceAsync
+    assert(!is.asyncFunction(this.create),
+      `egg:singleton ${this.name} only support create asynchronous, please use createInstanceAsync`);
     // options.default will be merge in to options.clients[id]
     config = Object.assign({}, this.options.default, config);
     return this.create(config, this.app);
   }
+
+  async createInstanceAsync(config) {
+    if (typeof config === 'function') {
+      // support config to be an async function or a normal function
+      config = await config();
+    }
+    // options.default will be merge in to options.clients[id]
+    config = Object.assign({}, this.options.default, config);
+    return await this.create(config, this.app);
+  }
 }
 
 module.exports = Singleton;

lib/egg.js

@@ -384,15 +384,16 @@ class EggApplication extends EggCore {
   /**
    * create a singleton instance
    * @param {String} name - unique name for singleton
-   * @param {Object} create - method will be invoked when singleton instance create
+   * @param {Function|AsyncFunction} create - method will be invoked when singleton instance create
    */
   addSingleton(name, create) {
     const options = {};
     options.name = name;
     options.create = create;
     options.app = this;
     const singleton = new Singleton(options);
-    singleton.init();
+    const done = this.readyCallback(`singleton:${name}`);
+    singleton.init().then(done);
   }
 
   _patchClusterClient(client) {

test/app/extend/agent.test.js

@@ -24,6 +24,25 @@ describe('test/app/extend/agent.test.js', () => {
       const ds = app.agent.dataService.createInstance({ foo: 'barrr' });
       config = await ds.getConfig();
       assert(config.foo === 'barrr');
+
+      const ds2 = await app.agent.dataService.createInstanceAsync({ foo: 'barrr' });
+      config = await ds2.getConfig();
+      assert(config.foo === 'barrr');
+
+      config = await app.agent.dataServiceAsync.get('second').getConfig();
+      assert(config.foo === 'bar');
+      assert(config.foo2 === 'bar2');
+
+      try {
+        app.agent.dataServiceAsync.createInstance({ foo: 'barrr' });
+        throw new Error('should not execute');
+      } catch (err) {
+        assert(err.message === 'egg:singleton dataServiceAsync only support create asynchronous, please use createInstanceAsync');
+      }
+
+      const ds4 = await app.agent.dataServiceAsync.createInstanceAsync({ foo: 'barrr' });
+      config = await ds4.getConfig();
+      assert(config.foo === 'barrr');
     });
   });
 });

test/app/extend/application.test.js

@@ -146,6 +146,25 @@ describe('test/app/extend/application.test.js', () => {
       const ds = app.dataService.createInstance({ foo: 'barrr' });
       config = await ds.getConfig();
       assert(config.foo === 'barrr');
+
+      const ds2 = await app.dataService.createInstanceAsync({ foo: 'barrr' });
+      config = await ds2.getConfig();
+      assert(config.foo === 'barrr');
+
+      config = await app.dataServiceAsync.get('first').getConfig();
+      assert(config.foo === 'bar');
+      assert(config.foo1 === 'bar1');
+
+      try {
+        app.dataServiceAsync.createInstance({ foo: 'barrr' });
+        throw new Error('should not execute');
+      } catch (err) {
+        assert(err.message === 'egg:singleton dataServiceAsync only support create asynchronous, please use createInstanceAsync');
+      }
+
+      const ds4 = await app.dataServiceAsync.createInstanceAsync({ foo: 'barrr' });
+      config = await ds4.getConfig();
+      assert(config.foo === 'barrr');
     });
   });
 

test/fixtures/apps/singleton-demo/agent.js

@@ -1,7 +1,9 @@
 'use strict';
 
-const createDataService = require('./create');
+const createDataService = require('./create').sync;
+const createDataServiceAsync = require('./create').async;
 
 module.exports = agent => {
   agent.addSingleton('dataService', createDataService);
+  agent.addSingleton('dataServiceAsync', createDataServiceAsync);
 };

test/fixtures/apps/singleton-demo/app.js

@@ -1,7 +1,9 @@
 'use strict';
 
-const createDataService = require('./create');
+const createDataService = require('./create').sync;
+const createDataServiceAsync = require('./create').async;
 
 module.exports = app => {
   app.addSingleton('dataService', createDataService);
+  app.addSingleton('dataServiceAsync', createDataServiceAsync);
 };

test/fixtures/apps/singleton-demo/config/config.default.js

@@ -3,7 +3,22 @@
 exports.dataService = {
   clients: {
     first: { foo1: 'bar1' },
-    second: { foo2: 'bar2' },
+    second: async () => {
+      return { foo2: 'bar2' };
+    },
+  },
+
+  default: {
+    foo: 'bar',
+  }
+};
+
+exports.dataServiceAsync = {
+  clients: {
+    first: { foo1: 'bar1' },
+    second: async () => {
+      return { foo2: 'bar2' };
+    },
   },
 
   default: {

test/fixtures/apps/singleton-demo/create.js

@@ -15,7 +15,15 @@ class DataService {
 }
 
 let count = 0;
-module.exports = function create(config, app) {
+
+exports.sync = (config, app) => {
+  const done = app.readyCallback(`DataService-${count++}`);
+  const dataService = new DataService(config);
+  dataService.ready(done);
+  return dataService;
+};
+
+exports.async = async (config, app) => {
   const done = app.readyCallback(`DataService-${count++}`);
   const dataService = new DataService(config);
   dataService.ready(done);