From 34e5b381141a153972917ae675ffcd5568bd2c12 Mon Sep 17 00:00:00 2001
From: mfogliatto <2962955+mfogliatto@users.noreply.github.com>
Date: Sun, 7 Jun 2026 08:05:40 +0000
Subject: [PATCH] fix: share ProjectCollection instance and implement
 IDisposable

Refactor MSBuildProjectMetadataProvider to use a single ProjectCollection
instance across both GetProjectReferences() and GetPropertyValue(),
eliminating redundant project loads when both methods are called for the
same project file.

Changes:
- MSBuildProjectMetadataProvider now holds a shared ProjectCollection
  created once in the constructor
- Added LoadOrGetProject() helper that caches loaded projects via
  ProjectCollection.GetLoadedProjects(), avoiding double evaluation
- Implemented IDisposable with proper dispose pattern to clean up the
  ProjectCollection (UnloadAllProjects + Dispose)
- ReferenceCopTask.Execute() now disposes the provider in a finally
  block using safe cast (as IDisposable)?.Dispose()

Fixes mfogliatto/ReferenceCop#68
---
 .../MSBuildProjectMetadataProvider.cs         | 58 +++++++++++++++++--
 src/ReferenceCop.MSBuild/ReferenceCopTask.cs  |  4 ++
 2 files changed, 57 insertions(+), 5 deletions(-)

diff --git a/src/ReferenceCop.MSBuild/Providers/MSBuildProjectMetadataProvider.cs b/src/ReferenceCop.MSBuild/Providers/MSBuildProjectMetadataProvider.cs
index 6710d5c..3f8ddaa 100644
--- a/src/ReferenceCop.MSBuild/Providers/MSBuildProjectMetadataProvider.cs
+++ b/src/ReferenceCop.MSBuild/Providers/MSBuildProjectMetadataProvider.cs
@@ -1,5 +1,6 @@
 namespace ReferenceCop.MSBuild
 {
+    using System;
     using System.Collections.Generic;
     using System.Linq;
     using Microsoft.Build.Evaluation;
@@ -7,11 +8,22 @@ namespace ReferenceCop.MSBuild
     /// <summary>
     /// Provides project reference information using MSBuild project evaluation.
     /// </summary>
-    public class MSBuildProjectMetadataProvider : IProjectMetadataProvider
+    public class MSBuildProjectMetadataProvider : IProjectMetadataProvider, IDisposable
     {
         private const string ProjectReferenceNode = "ProjectReference";
         private const string NoWarnMetadata = "NoWarn";
 
+        private readonly ProjectCollection projectCollection;
+        private bool disposed;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="MSBuildProjectMetadataProvider"/> class.
+        /// </summary>
+        public MSBuildProjectMetadataProvider()
+        {
+            this.projectCollection = new ProjectCollection();
+        }
+
         /// <summary>
         /// Gets the project references from a project file.
         /// </summary>
@@ -19,8 +31,7 @@ public class MSBuildProjectMetadataProvider : IProjectMetadataProvider
         /// <returns>The collection of project references.</returns>
         public IEnumerable<ProjectReferenceInfo> GetProjectReferences(string projectFilePath)
         {
-            var projectCollection = new ProjectCollection();
-            var project = projectCollection.LoadProject(projectFilePath);
+            var project = this.LoadOrGetProject(projectFilePath);
 
             // Get all ProjectReference items. These are the direct project references.
             var projectReferences = project.GetItems(ProjectReferenceNode);
@@ -47,11 +58,48 @@ public IEnumerable<ProjectReferenceInfo> GetProjectReferences(string projectFile
         /// <returns>The resolved property value.</returns>
         public string GetPropertyValue(string projectFilePath, string propertyName)
         {
-            var projectCollection = new ProjectCollection();
-            var project = projectCollection.LoadProject(projectFilePath);
+            var project = this.LoadOrGetProject(projectFilePath);
             project.ReevaluateIfNecessary();
 
             return project.GetPropertyValue(propertyName);
         }
+
+        /// <inheritdoc />
+        public void Dispose()
+        {
+            this.Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        /// <summary>
+        /// Releases the resources used by the <see cref="MSBuildProjectMetadataProvider"/>.
+        /// </summary>
+        /// <param name="disposing">Whether managed resources should be disposed.</param>
+        protected virtual void Dispose(bool disposing)
+        {
+            if (!this.disposed)
+            {
+                if (disposing)
+                {
+                    this.projectCollection.UnloadAllProjects();
+                    this.projectCollection.Dispose();
+                }
+
+                this.disposed = true;
+            }
+        }
+
+        private Project LoadOrGetProject(string projectFilePath)
+        {
+            var fullPath = System.IO.Path.GetFullPath(projectFilePath);
+            var loaded = this.projectCollection.GetLoadedProjects(fullPath);
+
+            if (loaded.Count > 0)
+            {
+                return loaded.First();
+            }
+
+            return this.projectCollection.LoadProject(fullPath);
+        }
     }
 }
diff --git a/src/ReferenceCop.MSBuild/ReferenceCopTask.cs b/src/ReferenceCop.MSBuild/ReferenceCopTask.cs
index d370247..d94d9aa 100644
--- a/src/ReferenceCop.MSBuild/ReferenceCopTask.cs
+++ b/src/ReferenceCop.MSBuild/ReferenceCopTask.cs
@@ -120,6 +120,10 @@ public bool Execute()
                 success = false;
                 this.BuildEngine.LogErrorEvent(ex);
             }
+            finally
+            {
+                (this.projectReferencesProvider as IDisposable)?.Dispose();
+            }
 
             return success;
         }