CmdPal: Adding a lock around perf monitor updates (#46061)

Based on reported bug in Teams.

Added lock around OnLoadBasePage._loadCount and modified
PerformanceWidgetPage to use Interlocked.Increment/Decrement on
_loadCount.

---------

Co-authored-by: leileizhang <leilzh@microsoft.com>
Co-authored-by: Niels Laute <niels.laute@live.nl>
Co-authored-by: moooyo <42196638+moooyo@users.noreply.github.com>
Co-authored-by: Yu Leng <yuleng@microsoft.com>
Co-authored-by: Kai Tao <69313318+vanzue@users.noreply.github.com>
Co-authored-by: Jiří Polášek <me@jiripolasek.com>
Co-authored-by: Shawn Yuan <128874481+shuaiyuanxx@users.noreply.github.com>
Co-authored-by: Gordon Lam <73506701+yeelam-gordon@users.noreply.github.com>
Co-authored-by: Heiko <61519853+htcfreek@users.noreply.github.com>
Co-authored-by: Mike Hall <mikehall@microsoft.com>
Co-authored-by: vanzue <vanzue@outlook.com>
Co-authored-by: Jaylyn Barbee <51131738+Jaylyn-Barbee@users.noreply.github.com>
Co-authored-by: Thanh Nguyen <74597207+ThanhNguyxn@users.noreply.github.com>
Co-authored-by: Zach Teutsch <88554871+zateutsch@users.noreply.github.com>

src/modules/MouseUtils/CursorWrap/MonitorTopology.cpp

@@ -14,7 +14,6 @@ void MonitorTopology::Initialize(const std::vector<MonitorInfo>& monitors)
     Logger::info(L"======= TOPOLOGY INITIALIZATION START =======");
     Logger::info(L"Initializing edge-based topology for {} monitors", monitors.size());
 
-
     m_monitors = monitors;
     m_outerEdges.clear();
     m_edgeMap.clear();
@@ -692,7 +691,6 @@ int MonitorTopology::GetAbsolutePosition(const MonitorEdge& edge, double relativ
     return static_cast<int>(result);
 }
 
-
 std::vector<MonitorTopology::GapInfo> MonitorTopology::DetectMonitorGaps() const
 {
     std::vector<GapInfo> gaps;

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Apps/AppListItem.cs

@@ -19,7 +19,6 @@ public sealed partial class AppListItem : ListItem, IPrecomputedListItem
 {
     private readonly AppCommand _appCommand;
     private readonly AppItem _app;
-
     private readonly Lazy<Task<IconInfo?>> _iconLoadTask;
     private readonly Lazy<Task<Details>> _detailsLoadTask;
 

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.PerformanceMonitor/OnLoadStaticPage.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Threading;
 using Microsoft.CommandPalette.Extensions;
 using Microsoft.CommandPalette.Extensions.Toolkit;
 using Windows.Foundation;
@@ -70,6 +71,7 @@ internal abstract partial class OnLoadContentPage : OnLoadBasePage, IContentPage
 
 internal abstract partial class OnLoadBasePage : Page
 {
+    private readonly Lock _loadLock = new();
     private int _loadCount;
 
 #pragma warning disable CS0067 // The event is never used
@@ -82,22 +84,28 @@ internal abstract partial class OnLoadBasePage : Page
         add
         {
             InternalItemsChanged += value;
-            if (_loadCount == 0)
+            lock (_loadLock)
             {
-                Loaded();
-            }
+                if (_loadCount == 0)
+                {
+                    Loaded();
+                }
 
-            _loadCount++;
+                _loadCount++;
+            }
         }
 
         remove
         {
             InternalItemsChanged -= value;
-            _loadCount--;
-            _loadCount = Math.Max(0, _loadCount);
-            if (_loadCount == 0)
+            lock (_loadLock)
             {
-                Unloaded();
+                _loadCount--;
+                _loadCount = Math.Max(0, _loadCount);
+                if (_loadCount == 0)
+                {
+                    Unloaded();
+                }
             }
         }
     }

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.PerformanceMonitor/PerformanceWidgetsPage.cs

@@ -9,6 +9,7 @@ using System.Globalization;
 using System.IO;
 using System.Text;
 using System.Text.Json.Nodes;
+using System.Threading;
 using CoreWidgetProvider.Helpers;
 using CoreWidgetProvider.Widgets.Enums;
 using Microsoft.CmdPal.Common;
@@ -262,17 +263,17 @@ internal abstract partial class WidgetPage : OnLoadContentPage
     /// </summary>
     internal virtual void PushActivate()
     {
-        _loadCount++;
+        Interlocked.Increment(ref _loadCount);
     }
 
     internal virtual void PopActivate()
     {
-        _loadCount--;
+        Interlocked.Decrement(ref _loadCount);
     }
 
     private int _loadCount;
 
-    protected bool IsActive => _loadCount > 0;
+    protected bool IsActive => Volatile.Read(ref _loadCount) > 0;
 
     protected override void Loaded()
     {