Call UpdateJumplist only if the settings changed

src/cascadia/TerminalApp/AppLogic.cpp

@@ -886,8 +886,27 @@ namespace winrt::TerminalApp::implementation
 
         // Register for directory change notification.
         _RegisterSettingsChange();
+        _ProcessLazySettingsChanges();
+    }
+
+    // Call this function after loading your _settings.
+    // It handles any updates which should only occur if the settings file changed.
+    void AppLogic::_ProcessLazySettingsChanges()
+    {
+        const auto hash = _settings.Hash();
+        const auto applicationState = ApplicationState::SharedInstance();
+        const auto cachedHash = applicationState.SettingsHash();
+
+        // The hash might be empty if LoadAll() failed and we're dealing with the defaults settings object.
+        // In that case we can just wait until the user fixed their settings or CascadiaSettings fixed
+        // itself and either will soon trigger a settings reload.
+        if (hash.empty() || hash == cachedHash)
+        {
+            return;
+        }
 
         Jumplist::UpdateJumplist(_settings);
+        applicationState.SettingsHash(hash);
     }
 
     // Method Description:
@@ -1058,8 +1077,7 @@ namespace winrt::TerminalApp::implementation
         _ApplyLanguageSettingChange();
         _RefreshThemeRoutine();
         _ApplyStartupTaskStateChange();
-
-        Jumplist::UpdateJumplist(_settings);
+        _ProcessLazySettingsChanges();
 
         _SettingsChangedHandlers(*this, nullptr);
     }

src/cascadia/TerminalApp/AppLogic.h

@@ -192,6 +192,7 @@ namespace winrt::TerminalApp::implementation
         void _OnLoaded(const IInspectable& sender, const Windows::UI::Xaml::RoutedEventArgs& eventArgs);
 
         [[nodiscard]] HRESULT _TryLoadSettings() noexcept;
+        void _ProcessLazySettingsChanges();
         void _RegisterSettingsChange();
         fire_and_forget _DispatchReloadSettings();
         void _ReloadSettings();

src/cascadia/TerminalSettingsModel/ApplicationState.h

@@ -35,6 +35,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
 // It provides X with the following arguments:
 //   (source, type, function name, JSON key, ...variadic construction arguments)
 #define MTSM_APPLICATION_STATE_FIELDS(X)                                                                                                                                  \
+    X(FileSource::Shared, winrt::hstring, SettingsHash, "settingsHash")                                                                                                   \
     X(FileSource::Shared, std::unordered_set<winrt::guid>, GeneratedProfiles, "generatedProfiles")                                                                        \
     X(FileSource::Local, Windows::Foundation::Collections::IVector<Model::WindowLayout>, PersistedWindowLayouts, "persistedWindowLayouts")                                \
     X(FileSource::Shared, Windows::Foundation::Collections::IVector<hstring>, RecentCommands, "recentCommands")                                                           \

src/cascadia/TerminalSettingsModel/ApplicationState.idl

@@ -33,13 +33,10 @@ namespace Microsoft.Terminal.Settings.Model
 
         Boolean IsStatePath(String filename);
 
-        Windows.Foundation.Collections.IVector<WindowLayout> PersistedWindowLayouts { get; set; };
-
-        Windows.Foundation.Collections.IVector<String> RecentCommands { get; set; };
-
-        Windows.Foundation.Collections.IVector<InfoBarMessage> DismissedMessages { get; set; };
-
-        Windows.Foundation.Collections.IVector<String> AllowedCommandlines { get; set; };
-
+        String SettingsHash;
+        Windows.Foundation.Collections.IVector<WindowLayout> PersistedWindowLayouts;
+        Windows.Foundation.Collections.IVector<String> RecentCommands;
+        Windows.Foundation.Collections.IVector<InfoBarMessage> DismissedMessages;
+        Windows.Foundation.Collections.IVector<String> AllowedCommandlines;
     }
 }

src/cascadia/TerminalSettingsModel/CascadiaSettings.cpp

@@ -43,6 +43,11 @@ winrt::com_ptr<Profile> Model::implementation::CreateChild(const winrt::com_ptr<
     return profile;
 }
 
+winrt::hstring CascadiaSettings::Hash() const noexcept
+{
+    return _hash;
+}
+
 Model::CascadiaSettings CascadiaSettings::Copy() const
 {
     const auto settings{ winrt::make_self<CascadiaSettings>() };

src/cascadia/TerminalSettingsModel/CascadiaSettings.h

@@ -113,6 +113,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         explicit CascadiaSettings(SettingsLoader&& loader);
 
         // user settings
+        winrt::hstring Hash() const noexcept;
         Model::CascadiaSettings Copy() const;
         Model::GlobalAppSettings GlobalSettings() const;
         winrt::Windows::Foundation::Collections::IObservableVector<Model::Profile> AllProfiles() const noexcept;
@@ -162,6 +163,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         void _validateThemeExists();
 
         // user settings
+        winrt::hstring _hash;
         winrt::com_ptr<implementation::GlobalAppSettings> _globals = winrt::make_self<implementation::GlobalAppSettings>();
         winrt::com_ptr<implementation::Profile> _baseLayerProfile = winrt::make_self<implementation::Profile>();
         winrt::Windows::Foundation::Collections::IObservableVector<Model::Profile> _allProfiles = winrt::single_threaded_observable_vector<Model::Profile>();

src/cascadia/TerminalSettingsModel/CascadiaSettings.idl

@@ -20,12 +20,14 @@ namespace Microsoft.Terminal.Settings.Model
         static String ApplicationVersion { get; };
 
         static void ExportFile(String path, String content);
-        
+
         CascadiaSettings(String userJSON, String inboxJSON);
 
         CascadiaSettings Copy();
         void WriteSettingsToDisk();
 
+        String Hash { get; };
+
         GlobalAppSettings GlobalSettings { get; };
 
         Profile ProfileDefaults { get; };

src/cascadia/TerminalSettingsModel/CascadiaSettingsSerialization.cpp

@@ -793,7 +793,8 @@ void SettingsLoader::_executeGenerator(const IDynamicProfileGenerator& generator
 Model::CascadiaSettings CascadiaSettings::LoadAll()
 try
 {
-    auto settingsString = ReadUTF8FileIfExists(_settingsPath()).value_or(std::string{});
+    FILETIME lastWriteTime{};
+    auto settingsString = ReadUTF8FileIfExists(_settingsPath(), false, &lastWriteTime).value_or(std::string{});
     auto firstTimeSetup = settingsString.empty();
 
     // If it's the firstTimeSetup and a preview build, then try to
@@ -874,6 +875,16 @@ try
             settings->_warnings.Append(SettingsLoadWarnings::FailedToWriteToSettings);
         }
     }
+    else
+    {
+        // There's no need to calculate a hash if mustWriteToDisk is true, because that will update
+        // settings.json on disk, which will trigger a file write event and cause AppLogic to call
+        // LoadAll() again. We'll then reach this point, because mustWriteToDisk will be false.
+        const ULARGE_INTEGER fileTime{ lastWriteTime.dwLowDateTime, lastWriteTime.dwHighDateTime };
+        const auto fileHash = til::hash(settingsString);
+        const auto hash = fmt::format(L"{:016x}-{:016x}", fileHash, fileTime.QuadPart);
+        settings->_hash = winrt::hstring{ hash };
+    }
 
     return *settings;
 }

src/cascadia/TerminalSettingsModel/FileUtils.cpp

@@ -107,7 +107,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model
     }
     // Tries to read a file somewhat atomically without locking it.
     // Strips the UTF8 BOM if it exists.
-    std::string ReadUTF8File(const std::filesystem::path& path, const bool elevatedOnly)
+    std::string ReadUTF8File(const std::filesystem::path& path, const bool elevatedOnly, FILETIME* lastWriteTime)
     {
         // From some casual observations we can determine that:
         // * ReadFile() always returns the requested amount of data (unless the file is smaller)
@@ -179,18 +179,23 @@ namespace winrt::Microsoft::Terminal::Settings::Model
                 buffer.erase(0, Utf8Bom.size());
             }
 
+            if (lastWriteTime)
+            {
+                THROW_IF_WIN32_BOOL_FALSE(GetFileTime(file.get(), nullptr, nullptr, lastWriteTime));
+            }
+
             return buffer;
         }
 
         THROW_WIN32_MSG(ERROR_READ_FAULT, "file size changed while reading");
     }
 
     // Same as ReadUTF8File, but returns an empty optional, if the file couldn't be opened.
-    std::optional<std::string> ReadUTF8FileIfExists(const std::filesystem::path& path, const bool elevatedOnly)
+    std::optional<std::string> ReadUTF8FileIfExists(const std::filesystem::path& path, const bool elevatedOnly, FILETIME* lastWriteTime)
     {
         try
         {
-            return { ReadUTF8File(path, elevatedOnly) };
+            return { ReadUTF8File(path, elevatedOnly, lastWriteTime) };
         }
         catch (const wil::ResultException& exception)
         {

src/cascadia/TerminalSettingsModel/FileUtils.h

@@ -5,8 +5,8 @@ namespace winrt::Microsoft::Terminal::Settings::Model
 {
     std::filesystem::path GetBaseSettingsPath();
     std::filesystem::path GetReleaseSettingsPath();
-    std::string ReadUTF8File(const std::filesystem::path& path, const bool elevatedOnly = false);
-    std::optional<std::string> ReadUTF8FileIfExists(const std::filesystem::path& path, const bool elevatedOnly = false);
+    std::string ReadUTF8File(const std::filesystem::path& path, const bool elevatedOnly = false, FILETIME* lastWriteTime = nullptr);
+    std::optional<std::string> ReadUTF8FileIfExists(const std::filesystem::path& path, const bool elevatedOnly = false, FILETIME* lastWriteTime = nullptr);
     void WriteUTF8File(const std::filesystem::path& path, const std::string_view& content, const bool elevatedOnly = false);
     void WriteUTF8FileAtomic(const std::filesystem::path& path, const std::string_view& content);
 }