Simplify access to Mumble context

Author: sliekens

GW2SDK.Tests/Features/Mumble/GameLinkTest.cs

@@ -50,13 +50,15 @@ public void The_link_provides_context()
     {
         using var sut = GameLink.Open();
 
-        var snapshot = sut.GetSnapshot();
-        Assert.True(snapshot.TryGetContext(out var actual));
-        Assert.True(actual.BuildId > 100_000, "Game build should be over 100,000");
+        var gameTick = sut.GetSnapshot();
+        Assert.True(gameTick.Context.BuildId > 100_000, "Game build should be over 100,000");
 
-        var server = actual.GetServerAddress();
+        var server = gameTick.Context.GetServerAddress();
         Assert.NotEmpty(server.ToString());
 
+        var address = gameTick.Context.GetServerAddress();
+        Assert.NotNull(address.Address);
+
         // Port is not specified
         Assert.Equal(0, server.Port);
     }

GW2SDK/Features/Mumble/Context.cs

@@ -63,9 +63,11 @@ public struct Context
 
     public bool IsMounted => MountIndex != 0;
 
+    [Pure]
     public IPEndPoint GetServerAddress() =>
         new(ServerAddress.sin_addr.s_un.s_addr, ServerAddress.sin_port);
 
+    [Pure]
     public MountName GetMount() =>
         MountIndex switch
         {

GW2SDK/Features/Mumble/GameTick.cs

@@ -34,38 +34,15 @@ public struct GameTick
     [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
     public readonly string Identity;
 
-    /// <summary>Despite the actual context containing more data, this value is always 48. This field tells Mumble to use the
-    /// first 48 bytes to uniquely identify people on the same server shards. The remaining 208 bytes are purely informational.</summary>
-    public readonly uint ContextLength;
+    /// <summary>This field tells Mumble to use the first 48 bytes of the Context to uniquely identify people on the same
+    /// server shards. It is internal because I don't expect anyone to find it useful.</summary>
+    internal readonly uint ContextLength;
 
-    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)]
-    internal readonly byte[] Context;
+    public readonly Context Context;
 
     [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 2048)]
     public readonly string Description;
 
-    public bool TryGetContext(out Context context)
-    {
-        context = default;
-        if (Name != "Guild Wars 2")
-        {
-            return false;
-        }
-
-        var handle = GCHandle.Alloc(Context, GCHandleType.Pinned);
-        try
-        {
-            var addr = handle.AddrOfPinnedObject();
-            context = Marshal.PtrToStructure<Context>(addr);
-        }
-        finally
-        {
-            handle.Free();
-        }
-
-        return true;
-    }
-
     public bool TryGetIdentity(
         [NotNullWhen(true)] out Identity? identity,
         MissingMemberBehavior missingMemberBehavior

samples/Mumble/GameReporter.cs

@@ -1,5 +1,4 @@
 using System;
-using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -48,15 +47,10 @@ protected override async Task ExecuteAsync(CancellationToken stoppingToken)
         // Subscribe to the GameLink observable
         // I recommend using Rx (System.Reactive) instead of implementing IObserver<T> yourself
         gameLink.Subscribe(
-            snapshot =>
+            tick =>
             {
                 // This callback is executed whenever the game client updates the shared memory
-                if (!snapshot.TryGetIdentity(out var identity, MissingMemberBehavior.Error))
-                {
-                    return;
-                }
-
-                if (!snapshot.TryGetContext(out var context))
+                if (!tick.TryGetIdentity(out var identity, MissingMemberBehavior.Error))
                 {
                     return;
                 }
@@ -70,41 +64,41 @@ protected override async Task ExecuteAsync(CancellationToken stoppingToken)
                 var map = mapsDictionary[identity.MapId];
 
                 var title = $"the {identity.Race} {identity.Profession}";
-                if (!context.UiState.HasFlag(UiState.GameHasFocus))
+                if (!tick.Context.UiState.HasFlag(UiState.GameHasFocus))
                 {
                     logger.LogInformation(
                         "[{UiTick}] {Name}, {Title} ({Specialization}) is afk",
-                        snapshot.UiTick,
+                        tick.UiTick,
                         identity.Name,
                         title,
                         specialization
                     );
                 }
-                else if (context.UiState.HasFlag(UiState.TextboxHasFocus))
+                else if (tick.Context.UiState.HasFlag(UiState.TextboxHasFocus))
                 {
                     logger.LogInformation(
                         "[{UiTick}] {Name}, {Title} ({Specialization}) is typing",
-                        snapshot.UiTick,
+                        tick.UiTick,
                         identity.Name,
                         title,
                         specialization
                     );
                 }
-                else if (context.UiState.HasFlag(UiState.IsMapOpen))
+                else if (tick.Context.UiState.HasFlag(UiState.IsMapOpen))
                 {
                     logger.LogInformation(
                         "[{UiTick}] {Name}, {Title} ({Specialization}) is looking at the map",
-                        snapshot.UiTick,
+                        tick.UiTick,
                         identity.Name,
                         title,
                         specialization
                     );
                 }
-                else if (context.UiState.HasFlag(UiState.IsInCombat))
+                else if (tick.Context.UiState.HasFlag(UiState.IsInCombat))
                 {
                     logger.LogInformation(
                         "[{UiTick}] {Name}, {Title} ({Specialization}) is in combat",
-                        snapshot.UiTick,
+                        tick.UiTick,
                         identity.Name,
                         title,
                         specialization
@@ -113,22 +107,22 @@ protected override async Task ExecuteAsync(CancellationToken stoppingToken)
                 else
                 {
                     var transport = "foot";
-                    if (context.IsMounted)
+                    if (tick.Context.IsMounted)
                     {
-                        transport = context.GetMount( ).ToString();
+                        transport = tick.Context.GetMount().ToString();
                     }
 
                     logger.LogInformation(
                         "[{UiTick}] {Name}, {Title} ({Specialization}) is on {Transport} in {Map}, Position: {{ Latitude = {X}, Longitude = {Z}, Elevation = {Y} }}",
-                        snapshot.UiTick,
+                        tick.UiTick,
                         identity.Name,
                         title,
                         specialization,
                         transport,
                         map.Name,
-                        snapshot.AvatarPosition.X,
-                        snapshot.AvatarPosition.Z,
-                        snapshot.AvatarPosition.Y
+                        tick.AvatarPosition.X,
+                        tick.AvatarPosition.Z,
+                        tick.AvatarPosition.Y
                     );
                 }
             },

samples/Mumble/Program.cs

@@ -27,7 +27,8 @@
         options.SingleLine = true;
         options.TimestampFormat = "HH:mm:ss.fff ";
         options.UseUtcTimestamp = true;
-    });
+    }
+);
 
 var app = builder.Build();