use cancellation tokens for connectivity check

Bloxstrap/RobloxDeployment.cs

@@ -18,24 +18,26 @@
             { "https://s3.amazonaws.com/setup.roblox.com", 4 }
         };
 
-        private static async Task<string?> TestConnection(string url, int priority)
+        private static async Task<string?> TestConnection(string url, int priority, CancellationToken token)
         {
             string LOG_IDENT = $"RobloxDeployment::TestConnection.{url}";
 
-            await Task.Delay(priority * 1000);
+            await Task.Delay(priority * 1000, token);
-
-            if (BaseUrl is not null)
-                return null;
 
             App.Logger.WriteLine(LOG_IDENT, "Connecting...");
 
             try
             {
-                var response = await App.HttpClient.GetAsync($"{url}/version");
+                var response = await App.HttpClient.GetAsync($"{url}/version", token);
                 
                 if (!response.IsSuccessStatusCode)
                     throw new HttpResponseException(response);
             }
+            catch (TaskCanceledException)
+            {
+                App.Logger.WriteLine(LOG_IDENT, "Connectivity test cancelled.");
+                throw;
+            }
             catch (Exception ex)
             {
                 App.Logger.WriteException(LOG_IDENT, ex);
@@ -59,8 +61,11 @@
             if (!String.IsNullOrEmpty(BaseUrl))
                 return null;
 
+            CancellationTokenSource tokenSource = new CancellationTokenSource();
+            CancellationToken token = tokenSource.Token;
+
             var exceptions = new List<Exception>();
-            var tasks = (from entry in BaseUrls select TestConnection(entry.Key, entry.Value)).ToList();
+            var tasks = (from entry in BaseUrls select TestConnection(entry.Key, entry.Value, token)).ToList();
 
             App.Logger.WriteLine(LOG_IDENT, "Testing connectivity...");
 
@@ -79,6 +84,9 @@
                 break;
             }
 
+            // stop other running connectivity tests
+            tokenSource.Cancel();
+
             if (String.IsNullOrEmpty(BaseUrl))
                 return exceptions[0];