Sort a list of servers by fastest ping time with Javascript

Question

In my Electron app I have a list of server addresses that I need to sort by shortest response time. I have a function that needs the sorted list:

function start() {
    // first step, get list of servers
    var servers_sorted = get_sorted_list_of_servers();

    // rest of function
}

Then I have a function that iterates through the list of servers:

function get_sorted_list_of_servers() {
    // access unsorted list from file

    unsorted_servers.forEach((server) => {
        // Get ping times for each server
        // Here is where I am stuck
    });

    // Sort based on ping times....

    return sorted_list_of_servers;
}

The problem is that I'm not sure how to get the ping time for each server. I've found a couple of libraries that wrap the ping utility ( net-ping and ping ). However, they use callbacks (which makes sense given that pinging a server can take a minute) and I need some way of getting a list of the server times.

// From ping example code
unsorted_servers.forEach(function (server) {
    ping.promise.probe(host).then(function (res) {
        console.log(res);
        // Update a global variable here??
    });
});

I've thought about letting the callbacks update a global list but then I need some way of signalling once all the servers have been tested.

Any guidance is appreciated. Thanks!

Answer 1

You can use Promise.all and map to loop over your server list and wait for all of the Promises to resolve. Here's a quick example using ping:

 const sortBy = require('lodash.sortby'); const ping = require('ping'); const servers = ['google.com', 'facebook.com', 'amazon.com', 'apple.com']; Promise.all(servers.map(server => ping.promise.probe(server))).then(response => { console.log(sortBy(response, 'time')) }); 

Here's an React demo using Promise.all and rendering the results:

https://server-ping-fuupenayzp.now.sh/

and the source

https://zeit.co/rusty-dev/server-ping/fuupenayzp/source?f=src/App.js