Workaround flakey EditorApplication.isCompiling property.

Version Handler relies upon EditorApplication.isCompiling to
determine whether an asset database refresh caused any editor
assemblies (DLLs) to be reloaded into the app domain.  However,
deterministic behavior of EditorApplication.isCompiling varies
across Unity versions.

This change works around EditorApplication.isCompiling
non-determinism by storing the set of editor assemblies that should
be enabled when the asset database has been refreshed and then
polls for them be loaded into the application domain before sending
a notification that the Version Handler has updated the project.
This _could_ have the side-effect of never notifying that the
project is ready if an assembly fails to load but that's better
than sending a notification before the app domain has been reloaded.

Bug: 150471207
Change-Id: If481784a7eb1256cc345464a274ec9cf5637830b

Author: Stewart Miles

source/VersionHandlerImpl/src/VersionHandlerImpl.cs

@@ -920,6 +920,16 @@ public FileMetadata MostRecentVersion {
             }
         }
 
+        /// <summary>
+        /// Backing store for EnabledEditorDlls.
+        /// </summary>
+        private HashSet<string> enabledEditorDlls = new HashSet<string>();
+
+        /// <summary>
+        /// Full path of DLLs that should be loaded into the editor application domain.
+        /// </summary>
+        public ICollection<string> EnabledEditorDlls { get { return enabledEditorDlls; } }
+
         /// <summary>
         /// Determine whether the PluginImporter class is available in
         /// UnityEditor. Unity 4 does not have the PluginImporter class so
@@ -975,6 +985,7 @@ public bool EnableMostRecentPlugins(HashSet<string> disableFiles) {
             int numberOfVersions = metadataByVersion.Count;
             var disabledVersions = new List<string>();
             string enabledVersion = null;
+            enabledEditorDlls = new HashSet<string>();
 
             // If the canonical file is out of date, update it.
             if (numberOfVersions > 0) {
@@ -1071,6 +1082,9 @@ public bool EnableMostRecentPlugins(HashSet<string> disableFiles) {
                                       dotNetVersionMessage),
                         verbose: true);
                     pluginImporter.SetCompatibleWithEditor(editorEnabled);
+                    if (metadata.filename.ToLower().EndsWith(".dll")) {
+                        enabledEditorDlls.Add(Path.GetFullPath(metadata.filename));
+                    }
                     modifiedThisVersion = true;
                 }
                 bool compatibleWithAnyPlatform = pluginImporter.GetCompatibleWithAnyPlatform();
@@ -1200,6 +1214,16 @@ public Dictionary<string, FileMetadata> MetadataByFilename {
             get { return metadataByFilename; }
         }
 
+        /// <summary>
+        /// Backing store for EnabledEditorDlls.
+        /// </summary>
+        private HashSet<string> enabledEditorDlls = new HashSet<string>();
+
+        /// <summary>
+        /// Full path of DLLs that should be loaded into the editor application domain.
+        /// </summary>
+        public ICollection<string> EnabledEditorDlls { get { return enabledEditorDlls; } }
+
         /// <summary>
         /// Construct an instance.
         /// </summary>
@@ -1226,6 +1250,7 @@ public static FileMetadataSet FilterOutReadOnlyFiles(FileMetadataSet metadataSet
         public void Clear() {
             metadataByCanonicalFilename = new Dictionary<string, FileMetadataByVersion>();
             metadataByFilename = new Dictionary<string, FileMetadata>();
+            enabledEditorDlls = new HashSet<string>();
         }
 
         /// <summary>
@@ -1545,6 +1570,7 @@ public bool EnableMostRecentPlugins(bool forceUpdate,
 
             foreach (var metadataByVersion in Values) {
                 modified |= metadataByVersion.EnableMostRecentPlugins(disableFiles);
+                enabledEditorDlls.UnionWith(metadataByVersion.EnabledEditorDlls);
             }
             return modified;
         }
@@ -2162,6 +2188,23 @@ private static bool Refreshing {
         }
     }
 
+    /// <summary>
+    /// Whether all editor DLLs have been loaded into the app domain.
+    /// </summary>
+    private static bool EnabledEditorDllsLoaded {
+        get {
+            var loadedAssemblyPaths = new HashSet<string>();
+            foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies()) {
+                try {
+                    loadedAssemblyPaths.Add(Path.GetFullPath(assembly.Location));
+                } catch (NotSupportedException) {
+                    // Dynamic assemblies do not have a file location so ignore.
+                }
+            }
+            return loadedAssemblyPaths.IsSupersetOf(enabledEditorDlls);
+        }
+    }
+
     /// <summary>
     /// Polls on main thread until compilation is finished prior to calling
     /// NotifyUpdateCompleteMethods() if an asset database refresh was in progress or
@@ -2183,15 +2226,15 @@ private static bool Refreshing {
     /// refreshing.</param>
     private static void NotifyWhenCompliationComplete(bool forceNotification) {
         RunOnMainThread.PollOnUpdateUntilComplete(() => {
-                if (EditorApplication.isCompiling) {
+                if (EditorApplication.isCompiling || !EnabledEditorDllsLoaded) {
                     if (!compiling) {
                         Log("Compiling...", verbose: true);
                     }
                     compiling = true;
-                    // In batch mode this can get stuck forever as PollOnUpdateUntilComplete()
-                    // will block the main thread which prevents the EditorApplication.isCompiling
-                    // flag from being updated by the editor.
-                    return ExecutionEnvironment.InBatchMode;
+                    // When running a single method this can get stuck forever as
+                    // PollOnUpdateUntilComplete() will block the main thread which prevents the
+                    // EditorApplication.isCompiling flag from being updated by the editor.
+                    return ExecutionEnvironment.ExecuteMethodEnabled;
                 }
                 if (compiling) {
                     Log("Compilation complete.", verbose: true);
@@ -2391,9 +2434,7 @@ public static void ShowSettings() {
     [MenuItem("Assets/External Dependency Manager/Version Handler/Update")]
     public static void UpdateNow() {
         UpdateVersionedAssets(true, () => {
-                if (!ExecutionEnvironment.InBatchMode) {
-                    Dialog.Display(PLUGIN_NAME, "Update complete.", 0, "OK");
-                }
+                Dialog.Display(PLUGIN_NAME, "Update complete.", 0, "OK");
             });
     }
 
@@ -2535,6 +2576,10 @@ public static void UpdateVersionedAssets(bool forceUpdate) {
         UpdateVersionedAssets(forceUpdate, () => {});
     }
 
+    /// <summary>
+    /// All editor DLLs enabled by the last pass of UpdateVersionedAssets().
+    /// </summary>
+    private static HashSet<string> enabledEditorDlls = new HashSet<string>();
 
     /// <summary>
     /// Find all files in the asset database with multiple version numbers
@@ -2565,6 +2610,7 @@ public static void UpdateVersionedAssets(bool forceUpdate, Action complete) {
         var obsoleteFiles = new ObsoleteFiles(
             ManifestReferences.FindAndReadManifests(allMetadataSet), allMetadataSet);
         if (metadataSet.EnableMostRecentPlugins(forceUpdate, obsoleteFiles.All)) {
+            enabledEditorDlls.UnionWith(metadataSet.EnabledEditorDlls);
             analytics.Report("enablemostrecentplugins", "Enable Most Recent Plugins");
             AssetDatabase.Refresh();
             Refreshing = true;