如何防止多个Socket.io事件监听器

时间：2017-07-04 01:42:10

标签： javascript node.js express socket.io

我需要能够从我的socket.io事件侦听器访问req。所以我这样做了：

服务器

var express = require('express'),
    app = express(),

app.set('view engine', 'pug');

app.use(express.static(__dirname + '/public'));

client = require('socket.io').listen(8080).sockets;

app.get('/', function (req, res) {
    client.on('connection', function (socket) {
        console.log("Connection")
    });
    res.render('chat');
});

app.listen(config.server.port, function() {
    console.log("Listening on port " + config.server.port);
});

客户端：

try {
        var socket = io.connect('http://127.0.0.1:8080');

    } catch(e) {
        //Set status to warn user
        console.log(e);
    }

问题是，如果在快速路由处理程序中添加socket.io事件侦听器，则会在套接字上创建多个侦听器。如果您要创建pug文件并测试此代码，您会注意到控制台记录＆＃34; connection＆＃34;一旦第一次刷新第二次，依此类推，因为每次处理路由时，都会添加另一个事件监听器。我可以通过将侦听器移动到路由处理程序之外来修复它，但是我需要能够访问＆＃34; req＆＃34;。有没有任何解决方案可以让我访问＆＃34; req＆＃34;并防止过多的听众被添加？

3 个答案:

答案 0 :(得分：2)

不幸的是，socket.io req事件监听器中访问的connection对象是声明事件监听器时的req，而不是事件监听器时的req被执行。因此，问题中提到的预期行为（如果我的理解是正确的）是不可能的。

这是一个简单的实验，对于有问题的代码：

app.get('/', function (req, res) {
  client.on('connection', function (socket) {
    console.log("req.url: " + req.url)
  });
  res.render('chat');
});

如果使用浏览器发送2个HTTP请求：首先是GET /?q=42，然后是GET /?q=88，则console.log结果将是：

//first request
req.url: /?q=42

//second request
req.url: /?q=42
req.url: /?q=88

对于第二个请求，当connection事件被侦听两次时，事件侦听器也将被执行两次。但是，执行结果不同 - 第一个HTTP请求中附加的事件侦听器在那时记住 req对象值。

如果只有一个客户端，并且没有并发请求（非常有限的情况），则有一种解决方法 - 将req保存为currentReq，并使事件监听器处理{{1} }：

currentReq

这里有一些想法为什么这是不可能的。

问题中的情景是：

  1. 浏览器向Node.js发送HTTP var currentReq; var isListened = false; // write logic in middleware, so it can be used in all routes. app.use(function(req, res, next) { currentReq = req; if (!isListened) { client.on('connection', function (socket) { console.log("req.url: " + currentReq.url) }); isListened = true; } next(); }); app.get('/', function (req, res) { res.render('chat'); }); 请求
  2. Node.js将HTML页面返回浏览器
  3. 浏览器解析并呈现HTML页面
  4. 浏览器向Node.js发送WebSocket连接请求
  5. Node.js建立WebSocket连接，并在控制台上打印日志。

    6. 很明显，当GET事件发生时（步骤5），HTTP connection（步骤1）早已消失。由于WebSocket和HTTP在不同端口上的连接不同，因此无法在步骤5中恢复初始HTTP请求信息。

答案 1 :(得分：0)

您可以通过控制台记录IsADirectoryError: [Errno 21] Is a directory: '/airflow/key/' [2019-09-10 04:56:59 +0000] [11] [INFO] Handling signal: ttou [2019-09-10 04:56:59 +0000] [5058] [INFO] Worker exiting (pid: 5058) [2019-09-10 04:57:29 +0000] [11] [INFO] Handling signal: ttin [2019-09-10 04:57:29 +0000] [5078] [INFO] Booting worker with pid: 5078 [2019-09-10 04:57:30,043] {__init__.py:51} INFO - Using executor KubernetesExecutor [2019-09-10 04:57:30,276] {dagbag.py:90} INFO - Filling up the DagBag from /airflow/dags/git [2019-09-10 04:57:30,810] {dagbag.py:205} ERROR - Failed to import: /airflow/dags/git/dag_test.py Traceback (most recent call last): File "/usr/local/lib/python3.7/site-packages/airflow/models/dagbag.py", line 202, in process_file m = imp.load_source(mod_name, filepath) File "/usr/local/lib/python3.7/imp.py", line 171, in load_source module = _load(spec) File "<frozen importlib._bootstrap>", line 696, in _load File "<frozen importlib._bootstrap>", line 677, in _load_unlocked File "<frozen importlib._bootstrap_external>", line 728, in exec_module File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed File "/airflow/dags/git/dag_test.py", line 50, in <module> a = get_data_from_bigquery(); File "/airflow/dags/git/dag_test.py", line 38, in get_data_from_bigquery bq = bigquery.Client() File "/usr/local/lib/python3.7/site-packages/google/cloud/bigquery/client.py", line 173, in __init__ project=project, credentials=credentials, _http=_http File "/usr/local/lib/python3.7/site-packages/google/cloud/client.py", line 226, in __init__ _ClientProjectMixin.__init__(self, project=project) File "/usr/local/lib/python3.7/site-packages/google/cloud/client.py", line 178, in __init__ project = self._determine_default(project) File "/usr/local/lib/python3.7/site-packages/google/cloud/client.py", line 193, in _determine_default return _determine_default_project(project) File "/usr/local/lib/python3.7/site-packages/google/cloud/_helpers.py", line 186, in _determine_default_project _, project = google.auth.default() File "/usr/local/lib/python3.7/site-packages/google/auth/_default.py", line 305, in default credentials, project_id = checker() File "/usr/local/lib/python3.7/site-packages/google/auth/_default.py", line 165, in _get_explicit_environ_credentials os.environ[environment_vars.CREDENTIALS]) File "/usr/local/lib/python3.7/site-packages/google/auth/_default.py", line 91, in _load_credentials_from_file with io.open(filename, 'r') as file_obj: IsADirectoryError: [Errno 21] Is a directory: '/airflow/key/' [2019-09-10 04:57:31 +0000] [11] [INFO] Handling signal: ttou [2019-09-10 04:57:31 +0000] [5062] [INFO] Worker exiting (pid: 5062) [2019-09-10 04:58:02 +0000] [11] [INFO] Handling signal: ttin [2019-09-10 04:58:02 +0000] [5082] [INFO] Booting worker with pid: 5082 [2019-09-10 04:58:02,692] {__init__.py:51} INFO - Using executor KubernetesExecutor [2019-09-10 04:58:02,932] {dagbag.py:90} INFO - Filling up the DagBag from /airflow/dags/git [2019-09-10 04:58:03,438] {dagbag.py:205} ERROR - Failed to import: /airflow/dags/git/dag_test.py Traceback (most recent call last): File "/usr/local/lib/python3.7/site-packages/airflow/models/dagbag.py", line 202, in process_file m = imp.load_source(mod_name, filepath) File "/usr/local/lib/python3.7/imp.py", line 171, in load_source module = _load(spec) File "<frozen importlib._bootstrap>", line 696, in _load File "<frozen importlib._bootstrap>", line 677, in _load_unlocked File "<frozen importlib._bootstrap_external>", line 728, in exec_module File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed File "/airflow/dags/git/dag_test.py", line 50, in <module> a = get_data_from_bigquery(); File "/airflow/dags/git/dag_test.py", line 38, in get_data_from_bigquery bq = bigquery.Client() File "/usr/local/lib/python3.7/site-packages/google/cloud/bigquery/client.py", line 173, in __init__ project=project, credentials=credentials, _http=_http File "/usr/local/lib/python3.7/site-packages/google/cloud/client.py", line 226, in __init__ _ClientProjectMixin.__init__(self, project=project) File "/usr/local/lib/python3.7/site-packages/google/cloud/client.py", line 178, in __init__ project = self._determine_default(project) File "/usr/local/lib/python3.7/site-packages/google/cloud/client.py", line 193, in _determine_default return _determine_default_project(project) File "/usr/local/lib/python3.7/site-packages/google/cloud/_helpers.py", line 186, in _determine_default_project _, project = google.auth.default() File "/usr/local/lib/python3.7/site-packages/google/auth/_default.py", line 305, in default credentials, project_id = checker() File "/usr/local/lib/python3.7/site-packages/google/auth/_default.py", line 165, in _get_explicit_environ_credentials os.environ[environment_vars.CREDENTIALS]) File "/usr/local/lib/python3.7/site-packages/google/auth/_default.py", line 91, in _load_credentials_from_file with io.open(filename, 'r') as file_obj: IsADirectoryError: [Errno 21] Is a directory: '/airflow/key/'

来查看记录的事件侦听器 
io.sockets

要解决您的问题，只需在初始化套接字连接之前放置此条件

Namespace {
  _events:
   { connection: [ [Function], [Function], [Function], [Function] ] },
  _eventsCount: 1 }

如果 if(io.sockets._events == undefined) { io.on('connection', socket => { ... }); } 之外还有其他事件侦听器

connection

答案 2 :(得分：0)

聚会有点晚了，但似乎 OP 想要访问 req 对象以验证登录。将我的 2 便士添加到组合中，这是我在类似情况下所做的：

我的应用程序使用基于 cookie 的登录令牌（仅通过 https！），我能够使用

访问登录 cookie 
function cookieParser(cookief) {
    let cookies = {}
    let _cookies = cookief.split("; ")
    for(cookiekv of cookief.split("; ")) {
        let kv = cookiekv.split("=")
        cookies[kv[0]] = kv[1]
    }
    return cookies
}
function verifyLogin(cookies) {
    //verify login cookies here. Change this example
    return cookies.loginToken
}
io.use(function(socket,next) {
    const cookies = cookieParser(socket.handshake.headers.cookie)
    if(verifyLogin(cookies)) {
        next()
    } else {
        next(new Error("invalid login token"))
    } 
})

这允许我只接受来自已登录并收到登录令牌的用户的套接字连接。这也应该解决您的多个侦听器方案，因为在 io 上仅注册了一个侦听器。

希望这会有所帮助！

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