Add missing usings (#20481)

The example was incomplete; `System.Threading.Thread` was being referenced without the namespace being properly imported.

Author: perlun

samples/snippets/standard/assembly/unloading/complex_assemblyloadcontext.cs

@@ -1,20 +1,26 @@
-class TestAssemblyLoadContext : AssemblyLoadContext
-{
-    private AssemblyDependencyResolver _resolver;
+using System.Reflection;
+using System.Runtime.Loader;
 
-    public TestAssemblyLoadContext(string mainAssemblyToLoadPath) : base(isCollectible: true)
+namespace complex
+{
+    class TestAssemblyLoadContext : AssemblyLoadContext
     {
-        _resolver = new AssemblyDependencyResolver(mainAssemblyToLoadPath);
-    }
+        private AssemblyDependencyResolver _resolver;
 
-    protected override Assembly Load(AssemblyName name)
-    {
-        string assemblyPath = _resolver.ResolveAssemblyToPath(name);
-        if (assemblyPath != null)
+        public TestAssemblyLoadContext(string mainAssemblyToLoadPath) : base(isCollectible: true)
         {
-            return LoadFromAssemblyPath(assemblyPath);
+            _resolver = new AssemblyDependencyResolver(mainAssemblyToLoadPath);
         }
 
-        return null;
+        protected override Assembly Load(AssemblyName name)
+        {
+            string assemblyPath = _resolver.ResolveAssemblyToPath(name);
+            if (assemblyPath != null)
+            {
+                return LoadFromAssemblyPath(assemblyPath);
+            }
+
+            return null;
+        }
     }
 }

samples/snippets/standard/assembly/unloading/simple_example.cs

@@ -1,62 +1,66 @@
-using System.Reflection;
+using System;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Runtime.Loader;
 
-// <Snippet1>
-class TestAssemblyLoadContext : AssemblyLoadContext
+namespace simple
 {
-    public TestAssemblyLoadContext() : base(isCollectible: true)
+    // <Snippet1>
+    class TestAssemblyLoadContext : AssemblyLoadContext
     {
-    }
+        public TestAssemblyLoadContext() : base(isCollectible: true)
+        {
+        }
 
-    protected override Assembly Load(AssemblyName name)
-    {
-        return null;
+        protected override Assembly Load(AssemblyName name)
+        {
+            return null;
+        }
     }
-}
-// </Snippet1>
+    // </Snippet1>
 
-class Test
-{
-    // <Snippet2>
-    [MethodImpl(MethodImplOptions.NoInlining)]
-    static int ExecuteAndUnload(string assemblyPath, out WeakReference alcWeakRef)
+    class Test
     {
-        // <Snippet3>
-        var alc = new TestAssemblyLoadContext();
-        Assembly a = alc.LoadFromAssemblyPath(assemblyPath);
-        // </Snippet3>
-
-        alcWeakRef = new WeakReference(alc, trackResurrection: true);
+        // <Snippet2>
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static int ExecuteAndUnload(string assemblyPath, out WeakReference alcWeakRef)
+        {
+            // <Snippet3>
+            var alc = new TestAssemblyLoadContext();
+            Assembly a = alc.LoadFromAssemblyPath(assemblyPath);
+            // </Snippet3>
 
-        // <Snippet4>
-        var args = new object[1] { new string[] {"Hello"}};
-        int result = (int)a.EntryPoint.Invoke(null, args);
-        // </Snippet4>
+            alcWeakRef = new WeakReference(alc, trackResurrection: true);
 
-        // <Snippet5>
-        alc.Unload();
-        // </Snippet5>
+            // <Snippet4>
+            var args = new object[1] {new string[] {"Hello"}};
+            int result = (int) a.EntryPoint.Invoke(null, args);
+            // </Snippet4>
 
-        return result;
-    }
-    // </Snippet2>
+            // <Snippet5>
+            alc.Unload();
+            // </Snippet5>
 
-    static void ExecuteAssemblyInUnloadableContext()
-    {
-        // <Snippet6>
-        WeakReference testAlcWeakRef;
-        int result = ExecuteAndUnload("absolute/path/to/your/assembly", out testAlcWeakRef);
-        // </Snippet6>
+            return result;
+        }
+        // </Snippet2>
 
-        // <Snippet7>
-        for (int i = 0; testAlcWeakRef.IsAlive && (i < 10); i++)
+        static void ExecuteAssemblyInUnloadableContext()
         {
-            GC.Collect();
-            GC.WaitForPendingFinalizers();
-        }
-        // </Snippet7>
+            // <Snippet6>
+            WeakReference testAlcWeakRef;
+            int result = ExecuteAndUnload("absolute/path/to/your/assembly", out testAlcWeakRef);
+            // </Snippet6>
+
+            // <Snippet7>
+            for (int i = 0; testAlcWeakRef.IsAlive && (i < 10); i++)
+            {
+                GC.Collect();
+                GC.WaitForPendingFinalizers();
+            }
+            // </Snippet7>
 
-        bool success = testAlcWeakRef.IsAlive;
+            bool success = testAlcWeakRef.IsAlive;
+        }
     }
-}
+}

samples/snippets/standard/assembly/unloading/unloadability_issues_example_test.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Runtime.InteropServices;
+using System.Threading;
 
 namespace test
 {
@@ -12,7 +13,7 @@ class Program
     {
         public static void ThreadProc()
         {
-            // Issue preventing unlopading #4 - a thread running method inside of the TestAssemblyLoadContext at the unload time
+            // Issue preventing unloading #4 - a thread running method inside of the TestAssemblyLoadContext at the unload time
             Thread.Sleep(Timeout.Infinite);
         }
 

samples/snippets/standard/assembly/unloading/unloading.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+    <StartupObject>test.Program</StartupObject>
+  </PropertyGroup>
+
+</Project>