Skip DECPS/MIDI output on Ctrl+C/Break (#14214)

Silent MIDI notes can be used to seemingly deny a user's input for long
durations (multiple minutes). This commit improves the situation by ignoring
all DECPS sequences for a second when Ctrl+C/Ctrl+Break is pressed.

Additionally it fixes a regression introduced in 666c446:
When we close a tab we need to unblock/shutdown `MidiAudio` early,
so that `ConptyConnection::Close()` can run down as fast as possible.

## Validation Steps Performed
* In pwsh in Windows Terminal 1.16 run ``while ($True) { echo "`e[3;8;3,~" }``
  * Ctrl+C doesn't do anything ❎
  * Closing the tab doesn't do anything ❎
* With these modifications in Windows Terminal:
  * Ctrl+C stops the output ✅
  * Closing the tab completes instantly ✅
* With these modifications in OpenConsole:
  * Ctrl+C stops the output ✅
  * Closing the window completes instantly ✅

src/audio/midi/MidiAudio.cpp

@@ -5,10 +5,6 @@
 #include "MidiAudio.hpp"
 #include "../terminal/parser/stateMachine.hpp"
 
-#include <dsound.h>
-
-#pragma comment(lib, "dxguid.lib")
-
 using Microsoft::WRL::ComPtr;
 using namespace std::chrono_literals;
 
@@ -17,12 +13,13 @@ using namespace std::chrono_literals;
 constexpr auto WAVE_SIZE = 16u;
 constexpr auto WAVE_DATA = std::array<byte, WAVE_SIZE>{ 128, 159, 191, 223, 255, 223, 191, 159, 128, 96, 64, 32, 0, 32, 64, 96 };
 
-MidiAudio::MidiAudio(HWND windowHandle)
+void MidiAudio::_initialize(HWND windowHandle) noexcept
 {
+    _hwnd = windowHandle;
     _directSoundModule.reset(LoadLibraryExW(L"dsound.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32));
     if (_directSoundModule)
     {
-        if (auto createFunction = GetProcAddressByFunctionDeclaration(_directSoundModule.get(), DirectSoundCreate8))
+        if (const auto createFunction = GetProcAddressByFunctionDeclaration(_directSoundModule.get(), DirectSoundCreate8))
         {
             if (SUCCEEDED(createFunction(nullptr, &_directSound, nullptr)))
             {
@@ -35,55 +32,29 @@ MidiAudio::MidiAudio(HWND windowHandle)
     }
 }
 
-MidiAudio::~MidiAudio() noexcept
+void MidiAudio::BeginSkip() noexcept
 {
-    try
-    {
-#pragma warning(suppress : 26447)
-        // We acquire the lock here so the class isn't destroyed while in use.
-        // If this throws, we'll catch it, so the C26447 warning is bogus.
-        const auto lock = std::unique_lock{ _inUseMutex };
-    }
-    catch (...)
-    {
-        // If the lock fails, we'll just have to live with the consequences.
-    }
+    _skip.SetEvent();
 }
 
-void MidiAudio::Initialize()
+void MidiAudio::EndSkip() noexcept
 {
-    _shutdownFuture = _shutdownPromise.get_future();
+    _skip.ResetEvent();
 }
 
-void MidiAudio::Shutdown()
-{
-    // Once the shutdown promise is set, any note that is playing will stop
-    // immediately, and the Unlock call will exit the thread ASAP.
-    _shutdownPromise.set_value();
-}
-
-void MidiAudio::Lock()
-{
-    _inUseMutex.lock();
-}
-
-void MidiAudio::Unlock()
-{
-    // We need to check the shutdown status before releasing the mutex,
-    // because after that the class could be destroyed.
-    const auto shutdownStatus = _shutdownFuture.wait_for(0s);
-    _inUseMutex.unlock();
-    // If the wait didn't timeout, that means the shutdown promise was set,
-    // so we need to exit the thread ASAP by throwing an exception.
-    if (shutdownStatus != std::future_status::timeout)
-    {
-        throw Microsoft::Console::VirtualTerminal::StateMachine::ShutdownException{};
-    }
-}
-
-void MidiAudio::PlayNote(const int noteNumber, const int velocity, const std::chrono::microseconds duration) noexcept
+void MidiAudio::PlayNote(HWND windowHandle, const int noteNumber, const int velocity, const std::chrono::milliseconds duration) noexcept
 try
 {
+    if (_skip.is_signaled())
+    {
+        return;
+    }
+
+    if (_hwnd != windowHandle)
+    {
+        _initialize(windowHandle);
+    }
+
     const auto& buffer = _buffers.at(_activeBufferIndex);
     if (velocity && buffer)
     {
@@ -106,10 +77,10 @@ try
         buffer->SetCurrentPosition((_lastBufferPosition + 12) % WAVE_SIZE);
     }
 
-    // By waiting on the shutdown future with the duration of the note, we'll
-    // either be paused for the appropriate amount of time, or we'll break out
-    // of the wait early if we've been shutdown.
-    _shutdownFuture.wait_for(duration);
+    // By waiting on the skip event with a maximum duration of the note, we'll
+    // either be paused for the appropriate amount of time, or we'll break out early
+    // because BeginSkip() was called. This happens for Ctrl+C or during shutdown.
+    _skip.wait(::base::saturated_cast<DWORD>(duration.count()));
 
     if (velocity && buffer)
     {

src/audio/midi/MidiAudio.hpp

@@ -12,8 +12,6 @@ Abstract:
 #pragma once
 
 #include <array>
-#include <future>
-#include <mutex>
 
 struct IDirectSound8;
 struct IDirectSoundBuffer;
@@ -21,27 +19,20 @@ struct IDirectSoundBuffer;
 class MidiAudio
 {
 public:
-    MidiAudio(HWND windowHandle);
-    MidiAudio(const MidiAudio&) = delete;
-    MidiAudio(MidiAudio&&) = delete;
-    MidiAudio& operator=(const MidiAudio&) = delete;
-    MidiAudio& operator=(MidiAudio&&) = delete;
-    ~MidiAudio() noexcept;
-    void Initialize();
-    void Shutdown();
-    void Lock();
-    void Unlock();
-    void PlayNote(const int noteNumber, const int velocity, const std::chrono::microseconds duration) noexcept;
+    void BeginSkip() noexcept;
+    void EndSkip() noexcept;
+    void PlayNote(HWND windowHandle, const int noteNumber, const int velocity, const std::chrono::milliseconds duration) noexcept;
 
 private:
+    void _initialize(HWND windowHandle) noexcept;
     void _createBuffers() noexcept;
 
+    wil::slim_event_manual_reset _skip;
+
+    HWND _hwnd = nullptr;
     wil::unique_hmodule _directSoundModule;
-    Microsoft::WRL::ComPtr<IDirectSound8> _directSound;
-    std::array<Microsoft::WRL::ComPtr<IDirectSoundBuffer>, 2> _buffers;
+    wil::com_ptr<IDirectSound8> _directSound;
+    std::array<wil::com_ptr<IDirectSoundBuffer>, 2> _buffers;
     size_t _activeBufferIndex = 0;
     DWORD _lastBufferPosition = 0;
-    std::promise<void> _shutdownPromise;
-    std::future<void> _shutdownFuture;
-    std::mutex _inUseMutex;
 };

src/audio/midi/precomp.h

@@ -25,7 +25,9 @@ Abstract:
 #endif
 
 // Windows Header Files:
-#include <windows.h>
+#include <Windows.h>
+
 #include <mmeapi.h>
+#include <dsound.h>
 
 // clang-format on

src/cascadia/TerminalControl/ControlCore.cpp

@@ -4,6 +4,10 @@
 #include "pch.h"
 #include "ControlCore.h"
 
+// MidiAudio
+#include <mmeapi.h>
+#include <dsound.h>
+
 #include <DefaultSettings.h>
 #include <unicode.hpp>
 #include <Utf16Parser.hpp>
@@ -241,8 +245,6 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         {
             _renderer->TriggerTeardown();
         }
-
-        _shutdownMidiAudio();
     }
 
     bool ControlCore::Initialize(const double actualWidth,
@@ -401,9 +403,33 @@ namespace winrt::Microsoft::Terminal::Control::implementation
                                     const WORD scanCode,
                                     const ::Microsoft::Terminal::Core::ControlKeyStates modifiers)
     {
+        if (ch == L'\x3') // Ctrl+C or Ctrl+Break
+        {
+            _handleControlC();
+        }
+
         return _terminal->SendCharEvent(ch, scanCode, modifiers);
     }
 
+    void ControlCore::_handleControlC()
+    {
+        if (!_midiAudioSkipTimer)
+        {
+            _midiAudioSkipTimer = _dispatcher.CreateTimer();
+            _midiAudioSkipTimer.Interval(std::chrono::seconds(1));
+            _midiAudioSkipTimer.IsRepeating(false);
+            _midiAudioSkipTimer.Tick([weakSelf = get_weak()](auto&&, auto&&) {
+                if (const auto self = weakSelf.get())
+                {
+                    self->_midiAudio.EndSkip();
+                }
+            });
+        }
+
+        _midiAudio.BeginSkip();
+        _midiAudioSkipTimer.Start();
+    }
+
     bool ControlCore::_shouldTryUpdateSelection(const WORD vkey)
     {
         // GH#6423 - don't update selection if the key that was pressed was a
@@ -1386,57 +1412,14 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     // - duration - How long the note should be sustained (in microseconds).
     void ControlCore::_terminalPlayMidiNote(const int noteNumber, const int velocity, const std::chrono::microseconds duration)
     {
-        // We create the audio instance on demand, and lock it for the duration
-        // of the note output so it can't be destroyed while in use.
-        auto& midiAudio = _getMidiAudio();
-        midiAudio.Lock();
-
-        // We then unlock the terminal, so the UI doesn't hang while we're busy.
+        // Unlock the terminal, so the UI doesn't hang while we're busy.
         auto& terminalLock = _terminal->GetReadWriteLock();
         terminalLock.unlock();
 
         // This call will block for the duration, unless shutdown early.
-        midiAudio.PlayNote(noteNumber, velocity, duration);
+        _midiAudio.PlayNote(reinterpret_cast<HWND>(_owningHwnd), noteNumber, velocity, std::chrono::duration_cast<std::chrono::milliseconds>(duration));
 
-        // Once complete, we reacquire the terminal lock and unlock the audio.
-        // If the terminal has shutdown in the meantime, the Unlock call
-        // will throw an exception, forcing the thread to exit ASAP.
         terminalLock.lock();
-        midiAudio.Unlock();
-    }
-
-    // Method Description:
-    // - Returns the MIDI audio instance, created on demand.
-    // Arguments:
-    // - <none>
-    // Return Value:
-    // - a reference to the MidiAudio instance.
-    MidiAudio& ControlCore::_getMidiAudio()
-    {
-        if (!_midiAudio)
-        {
-            const auto windowHandle = reinterpret_cast<HWND>(_owningHwnd);
-            _midiAudio = std::make_unique<MidiAudio>(windowHandle);
-            _midiAudio->Initialize();
-        }
-        return *_midiAudio;
-    }
-
-    // Method Description:
-    // - Shuts down the MIDI audio system if previously instantiated.
-    // Arguments:
-    // - <none>
-    // Return Value:
-    // - <none>
-    void ControlCore::_shutdownMidiAudio()
-    {
-        if (_midiAudio)
-        {
-            // We lock the terminal here to make sure the shutdown promise is
-            // set before the audio is unlocked in the thread that is playing.
-            auto lock = _terminal->LockForWriting();
-            _midiAudio->Shutdown();
-        }
     }
 
     bool ControlCore::HasSelection() const
@@ -1521,6 +1504,9 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         {
             _closing = true;
 
+            // Ensure Close() doesn't hang, waiting for MidiAudio to finish playing an hour long song.
+            _midiAudio.BeginSkip();
+
             // Stop accepting new output and state changes before we disconnect everything.
             _connection.TerminalOutput(_connectionOutputEventToken);
             _connectionStateChangedRevoker.revoke();

src/cascadia/TerminalControl/ControlCore.h

@@ -288,6 +288,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         void _updateSelectionUI();
         bool _shouldTryUpdateSelection(const WORD vkey);
 
+        void _handleControlC();
         void _sendInputToConnection(std::wstring_view wstr);
 
 #pragma region TerminalCoreCallbacks
@@ -305,10 +306,8 @@ namespace winrt::Microsoft::Terminal::Control::implementation
                                    const std::chrono::microseconds duration);
 #pragma endregion
 
-        std::unique_ptr<MidiAudio> _midiAudio;
-
-        MidiAudio& _getMidiAudio();
-        void _shutdownMidiAudio();
+        MidiAudio _midiAudio;
+        winrt::Windows::System::DispatcherQueueTimer _midiAudioSkipTimer{ nullptr };
 
 #pragma region RendererCallbacks
         void _rendererWarning(const HRESULT hr);

src/host/consoleInformation.cpp

@@ -4,6 +4,10 @@
 #include "precomp.h"
 #include <intsafe.h>
 
+// MidiAudio
+#include <mmeapi.h>
+#include <dsound.h>
+
 #include "misc.h"
 #include "output.h"
 #include "srvinit.h"
@@ -373,38 +377,14 @@ Microsoft::Console::CursorBlinker& CONSOLE_INFORMATION::GetCursorBlinker() noexc
 }
 
 // Method Description:
-// - Returns the MIDI audio instance, created on demand.
+// - Returns the MIDI audio instance.
 // Arguments:
 // - <none>
 // Return Value:
 // - a reference to the MidiAudio instance.
 MidiAudio& CONSOLE_INFORMATION::GetMidiAudio()
 {
-    if (!_midiAudio)
-    {
-        const auto windowHandle = ServiceLocator::LocateConsoleWindow()->GetWindowHandle();
-        _midiAudio = std::make_unique<MidiAudio>(windowHandle);
-        _midiAudio->Initialize();
-    }
-    return *_midiAudio;
-}
-
-// Method Description:
-// - Shuts down the MIDI audio system if previously instantiated.
-// Arguments:
-// - <none>
-// Return Value:
-// - <none>
-void CONSOLE_INFORMATION::ShutdownMidiAudio()
-{
-    if (_midiAudio)
-    {
-        // We lock the console here to make sure the shutdown promise is
-        // set before the audio is unlocked in the thread that is playing.
-        LockConsole();
-        _midiAudio->Shutdown();
-        UnlockConsole();
-    }
+    return _midiAudio;
 }
 
 // Method Description:

src/host/globals.cpp

@@ -5,6 +5,10 @@
 
 #include "globals.h"
 
+// MidiAudio
+#include <mmeapi.h>
+#include <dsound.h>
+
 #pragma hdrstop
 
 Globals::Globals()

src/host/input.cpp

@@ -242,6 +242,24 @@ void HandleCtrlEvent(const DWORD EventType)
     }
 }
 
+static void CALLBACK midiSkipTimerCallback(HWND, UINT, UINT_PTR idEvent, DWORD) noexcept
+{
+    auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
+    auto& midiAudio = gci.GetMidiAudio();
+
+    KillTimer(nullptr, idEvent);
+    midiAudio.EndSkip();
+}
+
+static void beginMidiSkip() noexcept
+{
+    auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
+    auto& midiAudio = gci.GetMidiAudio();
+
+    midiAudio.BeginSkip();
+    SetTimer(nullptr, 0, 1000, midiSkipTimerCallback);
+}
+
 void ProcessCtrlEvents()
 {
     auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
@@ -251,6 +269,8 @@ void ProcessCtrlEvents()
         return;
     }
 
+    beginMidiSkip();
+
     // Make our own copy of the console process handle list.
     const auto LimitingProcessId = gci.LimitingProcessId;
     gci.LimitingProcessId = 0;

src/host/output.cpp

@@ -512,8 +512,6 @@ void CloseConsoleProcessState()
 
     HandleCtrlEvent(CTRL_CLOSE_EVENT);
 
-    gci.ShutdownMidiAudio();
-
     // Jiggle the handle: (see MSFT:19419231)
     // When we call this function, we'll only actually close the console once
     //      we're totally unlocked. If our caller has the console locked, great,

src/host/outputStream.cpp

@@ -373,22 +373,15 @@ void ConhostInternalGetSet::SetWorkingDirectory(const std::wstring_view /*uri*/)
 // - true if successful. false otherwise.
 void ConhostInternalGetSet::PlayMidiNote(const int noteNumber, const int velocity, const std::chrono::microseconds duration)
 {
-    // We create the audio instance on demand, and lock it for the duration
-    // of the note output so it can't be destroyed while in use.
-    auto& midiAudio = ServiceLocator::LocateGlobals().getConsoleInformation().GetMidiAudio();
-    midiAudio.Lock();
-
-    // We then unlock the console, so the UI doesn't hang while we're busy.
+    // Unlock the console, so the UI doesn't hang while we're busy.
     UnlockConsole();
 
     // This call will block for the duration, unless shutdown early.
-    midiAudio.PlayNote(noteNumber, velocity, duration);
+    const auto windowHandle = ServiceLocator::LocateConsoleWindow()->GetWindowHandle();
+    auto& midiAudio = ServiceLocator::LocateGlobals().getConsoleInformation().GetMidiAudio();
+    midiAudio.PlayNote(windowHandle, noteNumber, velocity, std::chrono::duration_cast<std::chrono::milliseconds>(duration));
 
-    // Once complete, we reacquire the console lock and unlock the audio.
-    // If the console has shutdown in the meantime, the Unlock call
-    // will throw an exception, forcing the thread to exit ASAP.
     LockConsole();
-    midiAudio.Unlock();
 }
 
 // Routine Description:

src/host/server.h

@@ -140,7 +140,6 @@ public:
     Microsoft::Console::CursorBlinker& GetCursorBlinker() noexcept;
 
     MidiAudio& GetMidiAudio();
-    void ShutdownMidiAudio();
 
     CHAR_INFO AsCharInfo(const OutputCellView& cell) const noexcept;
 
@@ -157,7 +156,7 @@ private:
 
     Microsoft::Console::VirtualTerminal::VtIo _vtIo;
     Microsoft::Console::CursorBlinker _blinker;
-    std::unique_ptr<MidiAudio> _midiAudio;
+    MidiAudio _midiAudio;
 };
 
 #define ConsoleLocked() (ServiceLocator::LocateGlobals()->getConsoleInformation()->ConsoleLock.OwningThread == NtCurrentTeb()->ClientId.UniqueThread)

src/interactivity/base/ServiceLocator.cpp

@@ -3,6 +3,10 @@
 
 #include "precomp.h"
 
+// MidiAudio
+#include <mmeapi.h>
+#include <dsound.h>
+
 #include "../inc/ServiceLocator.hpp"
 
 #include "InteractivityFactory.hpp"