如何在 Node.js 中为 zmq 请求设置超时

Question

我编写了以下等待响应的代码。如果我在 5 秒后没有收到响应，如何注册超时回调？

var zmqRequest = zmq.socket('req');
zmqRequest.connect('tcp://localhost:8188');
zmqRequest.send(request.params.fileGuid);
console.log('request sent ' + request.params.fileGuid);
zmqRequest.on('message', function(msg){ // report back to the user... }); 

Answer 1

我写了一个函数，它使用setTimeout来检查超时的请求。这个例子使用Typescript，但应该很容易翻译成vanilla javascript。

import * as zmq from 'zmq';
function sendZMQRequest(params:any, doneCallback:(error:any, results:any) => void):void{
    // init zmq socket.
    var zmqreq = zmq.socket('req');
    var connectAddress = 'tcp://0.0.0.0:8200';
    zmqreq.connect(connectAddress);
    // uses setTimeout later.
    var timeout;
    // callback for zmq response.
    var requestCallback = (response:Buffer) => {
        // clear the timer when a response comes back.
        clearTimeout(timeout);
        // parse response and add any error checking you might need.
        if(response){
            var parsedResp = JSON.parse(response.toString('utf8'));
            doneCallback(null, parsedResp);
        } else {
            doneCallback(new Error('Bad Response'), null);
        }
    };
    zmqreq.send(params);
    timeout = setTimeout(() => {
        zmqreq.close();
        zmqreq.removeListener('message', requestCallback);
        doneCallback(new Error('Request Timed Out After 3 Seconds'), null);
    }, 3000);
    zmqreq.on('message', requestCallback);
}