feat: suppory async

.travis.yml

@@ -1,7 +1,7 @@
 sudo: false
 language: node_js
 node_js:
-  - '6'
+  - '8'
 install:
   - npm i npminstall && npminstall
 env:

example/producer.js

@@ -1,20 +1,23 @@
 'use strict';
 
-const co = require('co');
 const logger = require('./logger');
 const config = require('./config');
 const httpclient = require('urllib');
 const Producer = require('../').Producer;
 const Message = require('../').Message;
 
 const producer = new Producer(Object.assign({ httpclient, logger }, config));
-co(function*() {
-  yield producer.ready();
-  const msg = new Message(config.topic, // topic
-    'TagA', // tag
-    'Hello ONS !!! ' // body
-  );
+(async () => {
+  try {
+    await producer.ready();
+    const msg = new Message(config.topic, // topic
+      'TagA', // tag
+      'Hello ONS !!! ' // body
+    );
 
-  const sendResult = yield producer.send(msg);
-  console.log(sendResult);
-}).catch(err => console.error(err));
+    const sendResult = await producer.send(msg);
+    console.log(sendResult);
+  } catch (err) {
+    console.error(err)
+  }
+})();

lib/channel.js

@@ -98,9 +98,9 @@ class Channel extends Base {
    * @param {Number} timeout - response timeout
    * @return {Object} response
    */
-  * invoke(command, timeout) {
+  async invoke(command, timeout) {
     this.beforeRequest(command);
-    return yield this.sendThunk({
+    return await this.sendThunk({
       id: command.opaque,
       data: command.encode(),
       timeout,
@@ -112,9 +112,9 @@ class Channel extends Base {
    * @param {RemotingCommand} command - remoting command
    * @return {void}
    */
-  * invokeOneway(command) {
+  async invokeOneway(command) {
     this.beforeRequest(command);
-    yield this.sendThunk({
+    await this.sendThunk({
       id: command.opaque,
       data: command.encode(),
       oneway: true,