Improve query cancellation and ResultCollection performance (#5370)

* Added cancellation token to downstream functions in query thread

* Remove initial lag in query

* Re add query delay

* Remove debug flag

src/modules/launcher/PowerLauncher/Helper/ResultCollection.cs

@@ -1,138 +1,45 @@
 using PowerLauncher.ViewModel;
-using System;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using System.Collections.Specialized;
-using System.Diagnostics;
-using System.Windows;
-using System.Windows.Threading;
 
 namespace PowerLauncher.Helper
 {
-    public class ResultCollection : ObservableCollection<ResultViewModel>
+    public class ResultCollection : List<ResultViewModel>, INotifyCollectionChanged
     {
-        /// <summary>
+        public event NotifyCollectionChangedEventHandler CollectionChanged;
-        /// This private variable holds the flag to
-        /// turn on and off the collection changed notification.
-        /// </summary>
-        private bool suspendCollectionChangeNotification;
 
-        /// <summary>
+        private int CompareResultViewModel(ResultViewModel c1, ResultViewModel c2)
-        /// Initializes a new instance of the FastObservableCollection class.
-        /// </summary>
-        public ResultCollection()
-            : base()
         {
-            this.suspendCollectionChangeNotification = false;
+            if (c1.Result.Score > c2.Result.Score)
-        }
-
-        /// <summary>
-        /// This event is overriden CollectionChanged event of the observable collection.
-        /// </summary>
-        //public override event NotifyCollectionChangedEventHandler CollectionChanged;
-
-        /// <summary>
-        /// Raises collection change event.
-        /// </summary>
-        public void NotifyChanges()
-        {
-            this.ResumeCollectionChangeNotification();
-            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
-        }
-
-        /// <summary>
-        /// Resumes collection changed notification.
-        /// </summary>
-        public void ResumeCollectionChangeNotification()
-        {
-            this.suspendCollectionChangeNotification = false;
-        }
-
-        /// <summary>
-        /// Suspends collection changed notification.
-        /// </summary>
-        public void SuspendCollectionChangeNotification()
-        {
-            this.suspendCollectionChangeNotification = true;
-        }
-
-        /// <summary>
-        /// This method removes all items that match a predicate
-        /// </summary>
-        /// <param name="predicate">predicate</param>
-        public void RemovePredicate(Predicate<ResultViewModel> predicate)
-        {
-            CheckReentrancy();
-
-            this.SuspendCollectionChangeNotification();
-            for (int i = Count - 1; i >= 0; i--)
             {
-                if (predicate(this[i]))
+                return -1;
-                {
-                    RemoveAt(i);
-                }
             }
-        }
+            else if (c1.Result.Score == c2.Result.Score)
-
-        /// <summary>
-        /// Update the results collection with new results, try to keep identical results
-        /// </summary>
-        /// <param name="newItems"></param>
-        public void Update(List<ResultViewModel> newItems)
-        {
-            if (newItems == null)
             {
-                throw new ArgumentNullException(nameof(newItems));
+                return 0;
-            }
-
-            int newCount = newItems.Count;
-            int oldCount = Items.Count;
-            int location = newCount > oldCount ? oldCount : newCount;
-
-            this.SuspendCollectionChangeNotification();
-            for (int i = 0; i < location; i++)
-            {
-                ResultViewModel oldResult = this[i];
-                ResultViewModel newResult = newItems[i];
-                if (!oldResult.Equals(newResult))
-                { // result is not the same update it in the current index
-                    this[i] = newResult;
-                }
-                else if (oldResult.Result.Score != newResult.Result.Score)
-                {
-                    this[i].Result.Score = newResult.Result.Score;
-                }
-            }
-
-            if (newCount >= oldCount)
-            {
-                for (int i = oldCount; i < newCount; i++)
-                {
-                    Add(newItems[i]);
-                }
             }
             else
             {
-                for (int i = oldCount - 1; i >= newCount; i--)
+                return 1;
-                {
-                    RemoveAt(i);
-                }
             }
         }
 
         /// <summary>
-        /// This collection changed event performs thread safe event raising.
+        /// sort the list in descending order of score
+        /// </summary>
+        public new void Sort()
+        {
+            base.Sort(CompareResultViewModel);
+        }
+
+        /// <summary>
+        /// Notify change in the List view items
         /// </summary>
         /// <param name="e">The event argument.</param>
-        protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
+        public void NotifyChanges()
         {
-            // Recommended is to avoid reentry 
+            CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
-            // in collection changed event while collection
-            // is getting changed on other thread.
-            if(!this.suspendCollectionChangeNotification)
-            {
-                base.OnCollectionChanged(e);
-            }
         }
+
     }
 }

src/modules/launcher/PowerLauncher/ViewModel/MainViewModel.cs

@@ -111,7 +111,7 @@ namespace PowerLauncher.ViewModel
                     Task.Run(() =>
                     {
                         PluginManager.UpdatePluginMetadata(e.Results, pair.Metadata, e.Query);
-                        UpdateResultView(e.Results, pair.Metadata, e.Query);
+                        UpdateResultView(e.Results, pair.Metadata, e.Query, _updateToken);
                     }, _updateToken);
                 };
             }
@@ -421,11 +421,11 @@ namespace PowerLauncher.ViewModel
                     r => StringMatcher.FuzzySearch(query, r.Title).IsSearchPrecisionScoreMet() ||
                          StringMatcher.FuzzySearch(query, r.SubTitle).IsSearchPrecisionScoreMet()
                 ).ToList();
-                History.AddResults(filtered, id);
+                History.AddResults(filtered, id, _updateToken);
             }
             else
             {
-                History.AddResults(results, id);
+                History.AddResults(results, id, _updateToken);
             }
         }
 
@@ -448,25 +448,36 @@ namespace PowerLauncher.ViewModel
                     Task.Run(() =>
                     {
                         Thread.Sleep(20);
-                        RemoveOldQueryResults(query);
                         var plugins = PluginManager.ValidPluginsForQuery(query);
 
                         try
                         {
                             currentCancellationToken.ThrowIfCancellationRequested();
-                            foreach(PluginPair plugin in plugins)
+
+                            var resultPluginPair = new List<(List<Result>, PluginMetadata)>();
+                            foreach (PluginPair plugin in plugins)
                             {
-                                if (!plugin.Metadata.Disabled && !currentCancellationToken.IsCancellationRequested)
+                                if (!plugin.Metadata.Disabled)
                                 {
                                     var results = PluginManager.QueryForPlugin(plugin, query);
+                                    resultPluginPair.Add((results, plugin.Metadata));
                                     currentCancellationToken.ThrowIfCancellationRequested();
-                                    lock (_addResultsLock)
-                                    {
-                                        UpdateResultView(results, plugin.Metadata, query);
-                                    }
                                 }
                             }
 
+                            lock (_addResultsLock)
+                            {
+                                RemoveOldQueryResults(query);
+                                foreach (var p in resultPluginPair)
+                                {
+                                    UpdateResultView(p.Item1, p.Item2, query, currentCancellationToken);
+                                    currentCancellationToken.ThrowIfCancellationRequested();
+                                }
+
+                                currentCancellationToken.ThrowIfCancellationRequested();
+                                Results.Results.Sort();
+                            }
+
                             currentCancellationToken.ThrowIfCancellationRequested();
                             Application.Current.Dispatcher.BeginInvoke(new Action(() =>
                             {
@@ -680,7 +691,7 @@ namespace PowerLauncher.ViewModel
         /// <summary>
         /// To avoid deadlock, this method should not called from main thread
         /// </summary>
-        public void UpdateResultView(List<Result> list, PluginMetadata metadata, Query originQuery)
+        public void UpdateResultView(List<Result> list, PluginMetadata metadata, Query originQuery, CancellationToken ct)
         {
             if (list == null)
             {
@@ -711,7 +722,8 @@ namespace PowerLauncher.ViewModel
 
             if (originQuery.RawQuery == _lastQuery.RawQuery)
             {
-                Results.AddResults(list, metadata.ID);
+                ct.ThrowIfCancellationRequested();
+                Results.AddResults(list, metadata.ID, ct);
             }
         }
 
@@ -724,7 +736,7 @@ namespace PowerLauncher.ViewModel
                 Title = "hello"
             };
             list.Add(r);
-            Results.AddResults(list, "0");
+            Results.AddResults(list, "0", _updateToken);
             Results.Clear();
             MainWindowVisibility = System.Windows.Visibility.Collapsed;
 

src/modules/launcher/PowerLauncher/ViewModel/ResultsViewModel.cs

@@ -1,7 +1,7 @@
 using PowerLauncher.Helper;
 using System;
 using System.Collections.Generic;
-using System.Linq;
+using System.Threading;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Data;
@@ -153,12 +153,12 @@ namespace PowerLauncher.ViewModel
 
         public void RemoveResultsExcept(PluginMetadata metadata)
         {
-            Results.RemovePredicate(r => r.Result.PluginID != metadata.ID);
+            Results.RemoveAll(r => r.Result.PluginID != metadata.ID);
         }
 
         public void RemoveResultsFor(PluginMetadata metadata)
         {
-            Results.RemovePredicate(r => r.Result.PluginID == metadata.ID);
+            Results.RemoveAll(r => r.Result.PluginID == metadata.ID);
         }
 
         public void SelectNextTabItem()
@@ -215,57 +215,22 @@ namespace PowerLauncher.ViewModel
         /// <summary>
         /// Add new results to ResultCollection
         /// </summary>
-        public void AddResults(List<Result> newRawResults, string resultId)
+        public void AddResults(List<Result> newRawResults, string resultId, CancellationToken ct)
         {
-            var newResults = NewResults(newRawResults, resultId);
+            if (newRawResults == null)
-            Results.Update(newResults);
+            {
-        }
+                throw new ArgumentNullException(nameof(newRawResults));
+            }
 
-        private List<ResultViewModel> NewResults(List<Result> newRawResults, string resultId)
+            List<ResultViewModel> newResults = new List<ResultViewModel>(newRawResults.Count);
-        {
+            foreach(Result r in newRawResults)
-            var results = Results.ToList();
+            {
-            var newResults = newRawResults.Select(r => new ResultViewModel(r)).ToList();
+                newResults.Add(new ResultViewModel(r));
-            var oldResults = results.Where(r => r.Result.PluginID == resultId).ToList();
+                ct.ThrowIfCancellationRequested();
-
+            }
-            // Find the same results in A (old results) and B (new newResults)          
+
-            var sameResults = oldResults
+            Results.RemoveAll(r => r.Result.PluginID == resultId);
-                                .Where(t1 => newResults.Any(x => x.Result.Equals(t1.Result)))
+            Results.AddRange(newResults);
-                                .ToList();
-
-            // remove result of relative complement of B in A
-            foreach (var result in oldResults.Except(sameResults))
-            {
-                results.Remove(result);
-            }
-
-            // update result with B's score and index position
-            foreach (var sameResult in sameResults)
-            {
-                int oldIndex = results.IndexOf(sameResult);
-                int oldScore = results[oldIndex].Result.Score;
-                var newResult = newResults[newResults.IndexOf(sameResult)];
-                int newScore = newResult.Result.Score;
-                if (newScore != oldScore)
-                {
-                    var oldResult = results[oldIndex];
-
-                    oldResult.Result.Score = newScore;
-                    oldResult.Result.OriginQuery = newResult.Result.OriginQuery;
-
-                    results.RemoveAt(oldIndex);
-                    int newIndex = InsertIndexOf(newScore, results);
-                    results.Insert(newIndex, oldResult);
-                }
-            }
-
-            // insert result in relative complement of A in B
-            foreach (var result in newResults.Except(sameResults))
-            {
-                int newIndex = InsertIndexOf(result.Result.Score, results);
-                results.Insert(newIndex, result);
-            }
-
-            return results;
         }
         #endregion