Make IPC port configurable via HostOptions

osu.Framework.Tests/Platform/HeadlessGameHostTest.cs

@@ -89,8 +89,8 @@ public void TestThreadSafetyResetOnEnteringThread()
         [Test]
         public void TestIpc()
         {
-            using (var server = new BackgroundGameHeadlessGameHost(@"server", new HostOptions { BindIPC = true }))
-            using (var client = new HeadlessGameHost(@"client", new HostOptions { BindIPC = true }))
+            using (var server = new BackgroundGameHeadlessGameHost(@"server", new HostOptions { IPCPort = 45356 }))
+            using (var client = new HeadlessGameHost(@"client", new HostOptions { IPCPort = 45356 }))
             {
                 Assert.IsTrue(server.IsPrimaryInstance, @"Server wasn't able to bind");
                 Assert.IsFalse(client.IsPrimaryInstance, @"Client was able to bind when it shouldn't have been able to");

osu.Framework.Tests/Platform/UserInputManagerTest.cs

@@ -13,7 +13,7 @@ public partial class UserInputManagerTest
         [Test]
         public void IsAliveTest()
         {
-            using (var client = new TestHeadlessGameHost(@"client", true))
+            using (var client = new TestHeadlessGameHost(@"client", 45356))
             {
                 var testGame = new TestTestGame();
                 client.Run(testGame);
@@ -25,8 +25,8 @@ private class TestHeadlessGameHost : TestRunHeadlessGameHost
         {
             public Drawable CurrentRoot => Root;
 
-            public TestHeadlessGameHost(string gameName, bool bindIPC)
-                : base(gameName, new HostOptions { BindIPC = bindIPC })
+            public TestHeadlessGameHost(string gameName, int? ipcPort)
+                : base(gameName, new HostOptions { IPCPort = ipcPort })
             {
             }
         }

osu.Framework/HostOptions.cs

@@ -11,9 +11,12 @@ namespace osu.Framework
     public class HostOptions
     {
         /// <summary>
-        /// Whether to bind the IPC port. See <see cref="IIpcHost"/> for more details on usage.
+        /// The IPC port to bind. This port should be between 1024 and 49151,
+        /// should be shared by all instances of a given osu!framework app,
+        /// but be distinct from IPC ports specified by other osu!framework apps.
+        /// See <see cref="IIpcHost"/> for more details on usage.
         /// </summary>
-        public bool BindIPC { get; set; }
+        public int? IPCPort { get; set; }
 
         /// <summary>
         /// Whether this is a portable installation. Will cause all game files to be placed alongside the executable, rather than in the standard data directory.

osu.Framework/Platform/DesktopGameHost.cs

@@ -15,15 +15,13 @@ namespace osu.Framework.Platform
 {
     public abstract class DesktopGameHost : SDL2GameHost
     {
-        public const int IPC_PORT = 45356;
-
         private TcpIpcProvider ipcProvider;
-        private readonly bool bindIPCPort;
+        private readonly int? ipcPort;
 
         protected DesktopGameHost(string gameName, HostOptions options = null)
             : base(gameName, options)
         {
-            bindIPCPort = Options.BindIPC;
+            ipcPort = Options.IPCPort;
             IsPortableInstallation = Options.PortableInstallation;
         }
 
@@ -57,13 +55,13 @@ protected override void SetupForRun()
 
         private void ensureIPCReady()
         {
-            if (!bindIPCPort)
+            if (ipcPort == null)
                 return;
 
             if (ipcProvider != null)
                 return;
 
-            ipcProvider = new TcpIpcProvider(IPC_PORT);
+            ipcProvider = new TcpIpcProvider(ipcPort.Value);
             ipcProvider.MessageReceived += OnMessageReceived;
 
             IsPrimaryInstance = ipcProvider.Bind();