[wip] persisting and reading dg spec for unloaded or out of current s…

…olution projects

src/NuGet.Core/NuGet.Commands/RestoreCommand/Utility/NoOpRestoreUtilities.cs

@@ -200,11 +200,12 @@ public static bool VerifyPackagesOnDisk(RestoreRequest request)
         /// </summary>
         public static string GetHash(RestoreRequest request)
         {
+            var dgSpec = request.DependencyGraphSpec;
+
             if (request.Project.RestoreMetadata.ProjectStyle == ProjectStyle.DotnetCliTool || request.Project.RestoreMetadata.ProjectStyle == ProjectStyle.PackageReference)
             {
-
                 var uniqueName = request.DependencyGraphSpec.Restore.First();
-                var dgSpec = request.DependencyGraphSpec.WithProjectClosure(uniqueName);
+                dgSpec = request.DependencyGraphSpec.WithProjectClosure(uniqueName);
 
                 foreach (var projectSpec in dgSpec.Projects){
                     // The project path where the tool is declared does not affect restore and is only used for logging and transparency.
@@ -222,15 +223,45 @@ public static string GetHash(RestoreRequest request)
                         projectSpec.RestoreSettings = null;
                     }
                 }
+            }
+
+            PersistHashedDGFileIfDebugging(dgSpec, request.Log);
+            PersistDGSpecFile(dgSpec, request, request.Log);
+            return dgSpec.GetHash();
+        }
+
+        private static void PersistDGSpecFile(DependencyGraphSpec spec, RestoreRequest request, ILogger log)
+        {
+            var dgPath = GetPersistedDGSpecFilePath(request);
+
+            if (dgPath == null)
+            {
+                return;
+            }
 
-                PersistHashedDGFileIfDebugging(dgSpec, request.Log);
-                return dgSpec.GetHash();
+            if (!Directory.Exists(dgPath))
+            {
+                DirectoryUtility.CreateSharedDirectory(dgPath);
             }
 
-            PersistHashedDGFileIfDebugging(request.DependencyGraphSpec, request.Log);
-            return request.DependencyGraphSpec.GetHash();
+            log.LogMinimal($"Persisting no-op dg to {dgPath}");
+            spec.Save(dgPath);
         }
 
+        private static string GetPersistedDGSpecFilePath(RestoreRequest request)
+        {
+            if (request.ProjectStyle == ProjectStyle.ProjectJson
+                || request.ProjectStyle == ProjectStyle.PackageReference
+                || request.ProjectStyle == ProjectStyle.Standalone)
+            {
+                var outputRoot = request.MSBuildProjectExtensionsPath ?? request.RestoreOutputPath;
+                var projFileName = Path.GetFileName(request.Project.RestoreMetadata.ProjectPath);
+                var dgFileName = string.Format(DependencyGraphSpec.DGSpecFileName, projFileName);
+                return Path.Combine(outputRoot, dgFileName);
+            }
+
+            return null;
+        }
 
         /// <summary>
         /// Write the dg file to a temp location if NUGET_PERSIST_NOOP_DG.
@@ -256,7 +287,7 @@ private static void PersistHashedDGFileIfDebugging(DependencyGraphSpec spec, ILo
                     DirectoryUtility.CreateSharedDirectory(Path.GetDirectoryName(path));
                 }
 
-                log.LogMinimal($"Persisting no-op dg to {path}");
+                log.LogMinimal($"Persisting no-op dg for debugging to {path}");
 
                 spec.Save(path);
             }

src/NuGet.Core/NuGet.PackageManagement/BuildIntegration/DependencyGraphRestoreUtility.cs

@@ -218,6 +218,8 @@ public static async Task<DependencyGraphSpec> GetSolutionRestoreSpec(
         {
             var dgSpec = new DependencyGraphSpec();
 
+            var uniqueProjectDependencies = new HashSet<string>(PathUtility.GetStringComparerBasedOnOS());
+
             var projects = (await solutionManager.GetNuGetProjectsAsync()).OfType<IDependencyGraphProject>();
 
             foreach (var project in projects)
@@ -235,6 +237,36 @@ public static async Task<DependencyGraphSpec> GetSolutionRestoreSpec(
                     {
                         dgSpec.AddRestore(packageSpec.RestoreMetadata.ProjectUniqueName);
                     }
+
+                    var projFileName = Path.GetFileName(packageSpec.RestoreMetadata.ProjectPath);
+                    var dgFileName = string.Format(DependencyGraphSpec.DGSpecFileName, projFileName);
+                    var persistedDGSpecPath = Path.Combine(packageSpec.RestoreMetadata.OutputPath, dgFileName);
+
+                    if (File.Exists(persistedDGSpecPath))
+                    {
+                        DependencyGraphSpec persistedDGSpec = null;
+
+                        var projectDependencies = packageSpec.RestoreMetadata.TargetFrameworks.SelectMany(target => target.ProjectReferences);
+
+                        foreach (var projectReference in projectDependencies)
+                        {
+                            if (!projects.Any(p => PathUtility.GetStringComparerBasedOnOS().Equals(p.MSBuildProjectPath, projectReference.ProjectPath)) &&
+                                uniqueProjectDependencies.Add(projectReference.ProjectUniqueName))
+                            {
+                                if (persistedDGSpec == null)
+                                {
+                                    persistedDGSpec = DependencyGraphSpec.Load(persistedDGSpecPath);
+                                }
+
+                                var dependentPackageSpec = persistedDGSpec.GetProjectSpec(projectReference.ProjectUniqueName);
+
+                                if (dependentPackageSpec != null)
+                                {
+                                    dgSpec.AddProject(dependentPackageSpec);
+                                }
+                            }
+                        }
+                    }
                 }
             }
             // Return dg file

src/NuGet.Core/NuGet.ProjectModel/DependencyGraphSpec.cs

@@ -14,6 +14,8 @@ namespace NuGet.ProjectModel
 {
     public class DependencyGraphSpec
     {
+        public static readonly string DGSpecFileName = "{0}.deps.json";
+
         private readonly SortedSet<string> _restore = new SortedSet<string>(PathUtility.GetStringComparerBasedOnOS());
         private readonly SortedDictionary<string, PackageSpec> _projects = new SortedDictionary<string, PackageSpec>(PathUtility.GetStringComparerBasedOnOS());