Merge pull request #716 from True-Velocity/fix/isolated-assemblies

Use assembly loading context to isolate loaded assemblies from AppDomain #714

.gitignore

@@ -181,3 +181,8 @@ project.lock.json
 /src/.vs
 /.vs
 src/.idea
+
+# VS Code settings
+.vscode/launch.json
+.vscode/settings.json
+.vscode/tasks.json

src/Mapster.Tool/DeferredDependencyAssemblyLoadContext.cs

@@ -0,0 +1,87 @@
+using System.Collections.Immutable;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.Loader;
+
+namespace Mapster.Tool
+{
+    //
+    // Summary:
+    //     Used for loading an assembly and its dependencies in an isolated assembly load context but deferring the resolution of
+    //     a subset of those assemblies to an already existing Assembly Load Context (likely the AssemblyLoadContext.Default
+    //     context that is used by the runtime by default at startup)
+    public class DeferredDependencyAssemblyLoadContext : AssemblyLoadContext
+    {
+        private readonly AssemblyDependencyResolver resolver;
+        private readonly ImmutableHashSet<string> deferredDependencyAssemblyNames;
+        private readonly AssemblyLoadContext deferToContext;
+
+        public DeferredDependencyAssemblyLoadContext(
+            string assemblyPath,
+            AssemblyLoadContext deferToContext,
+            params AssemblyName[] deferredDependencyAssemblyNames
+        )
+        {
+            // set up a resolver for the dependencies of this non-deferred assembly
+            resolver = new AssemblyDependencyResolver(assemblyPath);
+
+            // store all of the assembly simple names that should be deferred w/
+            // the sharing assembly context loader (and not resolved exclusively in this loader)
+            this.deferredDependencyAssemblyNames = deferredDependencyAssemblyNames
+                .Select(an => an.Name!)
+                .Where(n => n != null)
+                .ToImmutableHashSet();
+
+            // store a reference to the assembly load context that assembly resolution will be deferred
+            // to when on the deferredDependencyAssemblyNames list
+            this.deferToContext = deferToContext;
+
+            // load the non-deferred assembly in this context to start
+            Load(GetAssemblyName(assemblyPath));
+        }
+
+        protected override Assembly? Load(AssemblyName assemblyName)
+        {
+            if (assemblyName.Name == null)
+            {
+                return null;
+            }
+
+            // if the assembly to be loaded is also set to be deferrred (based on constructor)
+            // then first attempt to load it from the sharing assembly load context
+            if (deferredDependencyAssemblyNames.Contains(assemblyName.Name))
+            {
+                return deferToContext.LoadFromAssemblyName(assemblyName);
+            }
+
+            // all other loaded assemblies should be considered dependencies of the
+            // non-deferred dependency loaded in the constructor and should be loaded
+            // from its path (the AssemblyDepedencyResolver resolves dependency paths)
+            string? assemblyPath = resolver.ResolveAssemblyToPath(assemblyName);
+            if (assemblyPath == null)
+            {
+                return null;
+            }
+
+            return LoadFromAssemblyPath(assemblyPath);
+        }
+
+        public static Assembly LoadAssemblyFrom(
+            string assemblyPath,
+            AssemblyLoadContext deferToContext,
+            params AssemblyName[] deferredDependencyAssemblyNames
+        )
+        {
+            DeferredDependencyAssemblyLoadContext loadContext =
+                new DeferredDependencyAssemblyLoadContext(
+                    assemblyPath,
+                    deferToContext,
+                    deferredDependencyAssemblyNames
+                );
+            return loadContext.LoadFromAssemblyName(
+                new AssemblyName(Path.GetFileNameWithoutExtension(assemblyPath))
+            );
+        }
+    }
+}