Use .NET 9 System.Threading.Lock. (#331)

.github/workflows/build.yaml

@@ -12,7 +12,7 @@ jobs:
       - name: Install .NET
         uses: actions/setup-dotnet@v3
         with:
-          dotnet-version: "8.0.x"
+          dotnet-version: "9.0.x"
 
       - name: Install reportgenerator tool
         run: dotnet tool install --global dotnet-reportgenerator-globaltool

src/Tmds.DBus.Protocol/Connection.cs

@@ -21,7 +21,7 @@ enum ConnectionState
         Disconnected
     }
 
-    private readonly object _gate = new object();
+    private readonly Lock _gate = new();
     private readonly ClientConnectionOptions _connectionOptions;
     private DBusConnection? _connection;
     private CancellationTokenSource? _connectCts;
@@ -97,7 +97,7 @@ private ValueTask<DBusConnection> ConnectCoreAsync(bool explicitConnect = false)
 
     private async Task<DBusConnection> DoConnectAsync()
     {
-        Debug.Assert(Monitor.IsEntered(_gate));
+        Debug.Assert(_gate.IsHeldByCurrentThread);
 
         DBusConnection? connection = null;
         try

src/Tmds.DBus.Protocol/DBusConnection.cs

@@ -101,7 +101,7 @@ public void Invoke(Exception? exception, Message message)
         private readonly object? _state4;
     }
 
-    private readonly object _gate = new object();
+    private readonly Lock _gate = new();
     private readonly Connection _parentConnection;
     private readonly Dictionary<uint, MessageHandler> _pendingCalls;
     private readonly CancellationTokenSource _connectCts;
@@ -903,7 +903,7 @@ MessageBuffer CreateAddMatchMessage(string ruleString)
 
     sealed class Observer : IDisposable
     {
-        private readonly object _gate = new object();
+        private readonly Lock _gate = new();
         private readonly SynchronizationContext? _synchronizationContext;
         private readonly MatchMaker _matchMaker;
         private readonly MessageHandler4 _messageHandler;

src/Tmds.DBus.Protocol/MessageBufferPool.cs

@@ -7,6 +7,7 @@ class MessageBufferPool
     public static readonly MessageBufferPool Shared = new MessageBufferPool(Environment.ProcessorCount * 2);
 
     private readonly int _maxSize;
+    private readonly Lock _gate = new();
     private readonly Stack<MessageBuffer> _pool = new Stack<MessageBuffer>();
 
     internal MessageBufferPool(int maxSize)
@@ -16,7 +17,7 @@ internal MessageBufferPool(int maxSize)
 
     public MessageBuffer Rent()
     {
-        lock (_pool)
+        lock (_gate)
         {
             if (_pool.Count > 0)
             {
@@ -31,7 +32,7 @@ public MessageBuffer Rent()
 
     internal void Return(MessageBuffer value)
     {
-        lock (_pool)
+        lock (_gate)
         {
             if (_pool.Count < _maxSize)
             {

src/Tmds.DBus.Protocol/Polyfill/Lock.cs

@@ -0,0 +1,11 @@
+#if !NET9_0_OR_GREATER
+
+namespace Tmds.DBus.Protocol;
+
+// Polyfill for System.Threading.Lock for use with the `lock` keyword.
+sealed class Lock
+{
+    public bool IsHeldByCurrentThread => Monitor.IsEntered(this);
+}
+
+#endif

src/Tmds.DBus.Protocol/Tmds.DBus.Protocol.csproj

@@ -1,10 +1,10 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;netstandard2.1;net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netstandard2.1;net6.0;net8.0;net9.0</TargetFrameworks>
     <Nullable>enable</Nullable>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <LangVersion>12</LangVersion>
+    <LangVersion>13</LangVersion>
     <IsAotCompatible Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net7.0'))">true</IsAotCompatible>
   </PropertyGroup>
 

src/Tmds.DBus.Protocol/UnixFdCollection.cs

@@ -11,23 +11,22 @@ sealed class UnixFdCollection : IReadOnlyList<SafeHandle>, IDisposable
 
     // The gate guards someone removing handles while the UnixFdCollection gets disposed by the message.
     // We don't need to lock it while adding handles, or reading them to send them.
-    private readonly object _gate;
     private bool _disposed;
     private bool _handlesReffed;
 
-    internal object SyncObject => _gate;
+    internal object SyncObject { get; }
 
     internal bool IsRawHandleCollection => _rawHandles is not null;
 
     internal UnixFdCollection(bool isRawHandleCollection = true)
     {
         if (isRawHandleCollection)
         {
-            _gate = _rawHandles = new();
+            SyncObject = _rawHandles = new();
         }
         else
         {
-            _gate = _handles = new();
+            SyncObject = _handles = new();
         }
     }
 
@@ -55,7 +54,7 @@ internal void AddHandle(SafeHandle handle)
     // We remain responsible for disposing the handle.
     public IntPtr ReadHandleRaw(int index)
     {
-        lock (_gate)
+        lock (SyncObject)
         {
             if (_disposed)
             {
@@ -103,7 +102,7 @@ private void ThrowDisposed()
     // The caller of this method owns the handle and is responsible for Disposing it.
     internal T? ReadHandleGeneric<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)]T>(int index)
     {
-        lock (_gate)
+        lock (SyncObject)
         {
             if (_disposed)
             {
@@ -155,7 +154,7 @@ IEnumerator IEnumerable.GetEnumerator()
 
     public void Dispose()
     {
-        lock (_gate)
+        lock (SyncObject)
         {
             if (_disposed)
             {
@@ -171,7 +170,7 @@ public void Dispose()
 
     internal void RefHandles()
     {
-        lock (_gate)
+        lock (SyncObject)
         {
             if (_disposed)
             {
@@ -206,7 +205,7 @@ internal void RefHandles()
 
     internal int DangerousGetHandle(int i)
     {
-        Debug.Assert(Monitor.IsEntered(_gate));
+        Debug.Assert(Monitor.IsEntered(SyncObject));
         if (!_handlesReffed)
         {
             throw new InvalidOperationException("Trying to send an unreffed handle.");

test/Tmds.DBus.Protocol.Tests/Tmds.DBus.Protocol.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <Nullable>enable</Nullable>
 
     <IsPackable>false</IsPackable>

test/Tmds.DBus.Tests/Tmds.DBus.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>..\..\sign.snk</AssemblyOriginatorKeyFile>
     <PublicSign>true</PublicSign>