Update tests network helper to be reliable in multi-threaded tests

1 files changed, 27 insertions, 10 deletions

diff --git a/mcs/class/test-helpers/NetworkHelpers.cs b/mcs/class/test-helpers/NetworkHelpers.cs
index 9d5eb114081..262b8d33232 100644
--- a/mcs/class/test-helpers/NetworkHelpers.cs
+++ b/mcs/class/test-helpers/NetworkHelpers.cs
@@ -1,12 +1,14 @@
 using System;
 using System.Net;
 using System.Net.Sockets;
+using System.Collections.Generic;
 
 namespace MonoTests.Helpers {
 
 	public static class NetworkHelpers
 	{
 		static Random rndPort = new Random ();
+		static HashSet<int> portsTable = new HashSet<int> ();
 
 		public static int FindFreePort ()
 		{
@@ -15,17 +17,32 @@ namespace MonoTests.Helpers {
 
 		public static IPEndPoint LocalEphemeralEndPoint ()
 		{
-			while (true) {
-				var ep = new IPEndPoint (IPAddress.Loopback, rndPort.Next (10000, 60000));
-
-				try {
-					using (var socket = new Socket (ep.AddressFamily, SocketType.Stream, ProtocolType.Tcp)) {
-						socket.Bind (ep);
-						socket.Close ();
-					}
-					return ep;
-				} catch (SocketException) { }
+			int counter = 0;
+
+			while (counter < 1000) {
+				var testingPort = rndPort.Next (10000, 60000);
+
+				var ep = new IPEndPoint (IPAddress.Loopback, testingPort);
+
+				lock (portsTable) {
+					if (portsTable.Contains (testingPort))
+						continue;
+
+					++counter;
+
+					try {
+						using (var socket = new Socket (ep.AddressFamily, SocketType.Stream, ProtocolType.Tcp)) {
+							socket.Bind (ep);
+							socket.Close ();
+						}
+
+						portsTable.Add (testingPort);
+						return ep;
+					} catch (SocketException) { }
+				}
 			}
+
+			throw new ApplicationException ($"Could not find available local port after {counter} retries");
 		}
 	}
 }