javascript - 在 Node.js 中创建 id 到套接字的映射，反之亦然

Question

我正在尝试管理一堆套接字连接。我的应用程序基本上是一个 http 服务器，它接收帖子并将其传递到套接字。当客户端打开套接字连接时，它们会发送带有 id 的连接消息:

{"m":"connect","id":"1"}

然后应用程序将此 ID 和套接字保存在 id2socket 和 socket2id 映射中。断开连接时，套接字/id 对将从映射中删除。

帖子还将包含一个 id，这表明帖子数据应发送到具有该 id 的套接字。

这太棒了，这对于单个打开的套接字来说效果很好。然而，当我打开多个套接字，然后关闭一个套接字时，断开连接会删除 map 上的所有内容。我认为我对 Node 中套接字的理解不完整 - 回调中是否仅使用一个套接字对象？有没有更好的方法来管理我的开放套接字连接和 ID？

启动服务器:

>>node server.js 
TCP server listening on 127.0.0.1:5280
HTTP server listening on 127.0.0.1:9002

远程登录:

>>telnet localhost 5280
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
{"m":"connect","id":"123"}
{"m":"connect","id":"123","success":"true"}

连接后的服务器:

>>Connection from 127.0.0.1:57572
received data: {"m":"connect","id":"123"}

id: 1
m: connect
associating uid 1 with socket [object Object]

发表帖子:

python post.py {"foo":"bar"}

因此，这对于多个打开的套接字来说效果很好(只要 1 个设备的 ID 为 123，服务器目前已将其硬连线)。但是，一旦关闭一个连接，所有套接字连接都会从映射中删除。

这是我的代码:

用于发布的 python 脚本:

import sys
import json
import httplib, urllib, urllib2

values = json.loads('{"foo":"bar"}')
headers = {"Content-type": "application/json"}

conn = httplib.HTTPConnection('127.0.0.1', 9002)
headers = {"Content-type": "application/json"}
conn.request("POST", "", json.dumps(values), headers)
response = conn.getresponse()

print "response.status: "+response.status
print "response.reason: "+response.reason
print "response.read: "+response.read()
conn.close()

Node 服务器(http 和 tcp)，通过硬连线将数据发送到 post 设备“123”:

var net = require('net'); // tcp-server
var http = require("http"); // http-server
var qs = require('querystring'); // http-post

// Map of sockets to devices
var id2socket = new Object;
var socket2id = new Object;

// Setup a tcp server
var server_plug = net.createServer(function(socket) {

    // Event handlers
    socket.addListener("connect", function(conn) {
        console.log("Connection from " + socket.remoteAddress + ":" + socket.remotePort );  
    });

    socket.addListener("data", function(data) {
        console.log("received data: " + data);
        try {
            request = JSON.parse(data);

            response = request;
            if(request.m !== undefined && request['id'] !== undefined){ // hack on 'id', id is js obj property
                console.log("id: "+request['id']);
                console.log("m: "+request.m);
                if(request.m == 'connect'){
                    console.log("associating uid " + request['id'] + " with socket " + socket);
                    id2socket[request['id']] = socket;
                    socket2id[socket] = request['id'];
                    response.success = 'true';
                } else {
                    response.success = 'true';
                }
            }
            socket.write(JSON.stringify(response));
        } catch (SyntaxError) {
            console.log('Invalid JSON:' + data);
            socket.write('{"success":"false","response":"invalid JSON"}');
        }
    });

    socket.on('end', function() {
        id = socket2id[socket]
        console.log("socket disconnect by id " + id);

        // wipe out the stored info
        console.log("removing from map socket:"+socket+" id:"+id);
        delete id2socket[id];
        delete socket2id[socket];
    });

    socket.on('timeout', function() {
        console.log('socket timeout');
    });

});

// Setup http server
var server_http = http.createServer(
    // Function to handle http:post requests, need two parts to it
    // http://jnjnjn.com/113/node-js-for-noobs-grabbing-post-content/
    function onRequest(request, response) {
        request.setEncoding("utf8");

        request.addListener("data", function(chunk) {
            request.content += chunk;
        });

        request.addListener("end", function() {
            console.log("post received!");
            //console.log("Request received: "+request.content);


            if (request.method == 'POST') {
                //var json = qs.parse(request.content);
                //console.log("Post: "+json);

                // HACK TO TEST STUFF:
                // send a message to one of the open sockets
                try {
                    var socket = id2socket['123']; //hardwired 
                    socket.write('{"m":"post"}');
                } catch (Error) {
                    console.log("Cannot find socket with id "+'123');
                }
            }
        });
    }
);


// Fire up the servers
var HOST = '127.0.0.1';
var PORT = 5280;
var PORT2 = 9002;

server_plug.listen(PORT, HOST);
console.log("TCP server listening on "+HOST+":"+PORT);

server_http.listen(PORT2);
console.log("HTTP server listening on "+HOST+":"+PORT2);

Answer 1

对象仅将字符串作为其属性的键。正如您的日志所示，套接字对象被转换为字符串 "[object Object]"。结果，套接字 #2 覆盖了对象中套接字 #1 的 id，因为所有套接字都被转换为相同的字符串键。因此，对象中始终只有一个属性，因为所有套接字都归结为同一个键。当您尝试删除套接字 #2 的 id 时，单个属性将被删除并且对象为空。

当用作键时，您似乎希望为每个单独的套接字提供一个自定义属性。您可以使用 WeakMap 来实现此目的。 WeakMap 确实允许对象作为键(而不是仅字符串键)，但由于它们相对较新，目前可能包含错误。

(请注意，id2socket 映射可以只是一个普通对象，因为数字可以很好地转换为字符串，并且每个数字都有自己不同的字符串表示形式^* .)

使用WeakMap如下:

var socket2id = new WeakMap; // as if you were doing: var socket2id = {};
socket2id.set(socket, id);   // as if you were doing: socket2id[socket] = id;
socket2id.get(socket);       // as if you were doing: socket2id[socket];
socket2id.delete(socket);    // as if you were doing: delete socket2id[socket];

确保使用 node --harmony (>= 0.7) 或 node --harmony_weakmaps (<= 0.6) 运行。

<小时/>

^* 0 和 -0 是异常(exception)，但无论如何您都不应该使用 -0 因为0 === -0，因此很难区分它们。