De-over-parallelize Versions tab

Core/Extensions/EnumerableExtensions.cs

@@ -68,6 +68,11 @@ public static Dictionary<K, V> ToDictionary<K, V>(this ParallelQuery<KeyValuePai
         public static ConcurrentDictionary<K, V> ToConcurrentDictionary<K, V>(this IEnumerable<KeyValuePair<K, V>> pairs)
             => new ConcurrentDictionary<K, V>(pairs);
 
+        public static IEnumerable<T> AsParallelIf<T>(this IEnumerable<T> source,
+                                                     bool                parallel)
+            => parallel ? source.AsParallel()
+                        : source;
+
         // https://stackoverflow.com/a/55591477/2422988
         public static ParallelQuery<T> WithProgress<T>(this ParallelQuery<T> source,
                                                        long                  totalCount,

Core/ModuleInstaller.cs

@@ -1399,7 +1399,7 @@ public bool CanInstall(List<CkanModule>            toInstall,
                                          .Where(m => m != null);
                 var resolver = new RelationshipResolver(toInstall, installed, opts, registry, crit);
 
-                var resolverModList = resolver.ModList().ToList();
+                var resolverModList = resolver.ModList(false).ToList();
                 if (resolverModList.Count >= toInstall.Count(m => !m.IsMetapackage))
                 {
                     // We can install with no further dependencies

Core/Relationships/RelationshipResolver.cs

@@ -519,10 +519,10 @@ private bool MightBeInstallable(CkanModule              module,
         /// Returns a list of all modules to install to satisfy the changes required.
         /// Each mod is after its dependencies and before its reverse dependencies.
         /// </summary>
-        public IEnumerable<CkanModule> ModList()
+        public IEnumerable<CkanModule> ModList(bool parallel = true)
             => modlist.Values
                       .Distinct()
-                      .AsParallel()
+                      .AsParallelIf(parallel)
                       // Put user choices at the bottom; .OrderBy(bool) -> false first
                       .OrderBy(m => ReasonsFor(m).Any(r => r is SelectionReason.UserRequested))
                       // Put dependencies before dependers
@@ -539,8 +539,8 @@ private static bool AnyRelationship(SelectionReason r)
                 || r is SelectionReason.Recommended
                 || r is SelectionReason.Suggested;
 
-        private IEnumerable<T> BreadthFirstSearch<T>(IEnumerable<T>                      startingGroup,
-                                                     Func<T, HashSet<T>, IEnumerable<T>> getNextGroup)
+        private static IEnumerable<T> BreadthFirstSearch<T>(IEnumerable<T>                      startingGroup,
+                                                            Func<T, HashSet<T>, IEnumerable<T>> getNextGroup)
         {
             var found    = startingGroup.ToHashSet();
             var toSearch = new Queue<T>(found);

Core/Types/CkanModule.cs

@@ -339,7 +339,7 @@ public CkanModule(
         /// <summary>
         /// Inflates a CKAN object from a JSON string.
         /// </summary>
-        public CkanModule(string json, IGameComparator comparator)
+        public CkanModule(string json, IGameComparator comparator = null)
         {
             try
             {
@@ -355,7 +355,7 @@ public CkanModule(string json, IGameComparator comparator)
                     string.Format(Properties.Resources.CkanModuleDeserialisationError, ex.Message),
                     ex);
             }
-            _comparator = comparator;
+            _comparator = comparator ?? ServiceLocator.Container.Resolve<IGameComparator>();
             CheckHealth();
             CalculateSearchables();
         }
@@ -510,18 +510,12 @@ public static string ToJson(CkanModule module)
         }
 
         /// <summary>
-        /// Generates a CKAN.META object from a string.
+        /// Generates a CkanModule object from a string.
         /// Also validates that all required fields are present.
         /// Throws a BadMetaDataKraken if any fields are missing.
         /// </summary>
         public static CkanModule FromJson(string json)
-        {
-            log.Debug("Inflating comparator object");
-            IGameComparator comparator = ServiceLocator.Container.Resolve<IGameComparator>();
-
-            log.Debug("Building CkanModule");
-            return new CkanModule(json, comparator);
-        }
+            => new CkanModule(json);
 
         #endregion
 

GUI/Controls/ModInfoTabs/Versions.cs

@@ -241,6 +241,7 @@ private void checkInstallable(ListViewItem[] items)
                        {
                            if (latestCompatible == null || item.Index < latestCompatible.Index)
                            {
+                               VersionsListView.BeginUpdate();
                                if (latestCompatible != null)
                                {
                                    // Revert color of previous best guess
@@ -250,6 +251,7 @@ private void checkInstallable(ListViewItem[] items)
                                latestCompatible = item;
                                item.BackColor = Color.Green;
                                item.ForeColor = Color.White;
+                               VersionsListView.EndUpdate();
                            }
                            else
                            {