Android: Fix rotating EmulationActivity after boot fails

Time for yet another new iteration of working around the
"surface destruction during boot" problem...
This time, the strategy is to use a mutex in MainAndroid.cpp.

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/NativeLibrary.java

@@ -403,15 +403,13 @@ public final class NativeLibrary
    */
   public static native void StopEmulation();
 
-  public static native boolean IsBooting();
-
-  public static native void WaitUntilDoneBooting();
-
   /**
    * Returns true if emulation is running (or is paused).
    */
   public static native boolean IsRunning();
 
+  public static native boolean IsRunningAndStarted();
+
   /**
    * Enables or disables CPU block profiling
    *
@@ -487,7 +485,7 @@ public final class NativeLibrary
   private static native String GetCurrentTitleDescriptionUnchecked();
 
   public static boolean displayAlertMsg(final String caption, final String text,
-          final boolean yesNo, final boolean isWarning)
+          final boolean yesNo, final boolean isWarning, final boolean nonBlocking)
   {
     Log.error("[NativeLibrary] Alert: " + text);
     final EmulationActivity emulationActivity = sEmulationActivity.get();
@@ -498,10 +496,9 @@ public final class NativeLibrary
     }
     else
     {
-      // AlertMessages while the core is booting will deadlock if WaitUntilDoneBooting is called.
-      // We also can't use AlertMessages unless we have a non-null activity reference.
-      // As a fallback, we use toasts instead.
-      if (emulationActivity == null || IsBooting())
+      // We can't use AlertMessages unless we have a non-null activity reference
+      // and are allowed to block. As a fallback, we can use toasts.
+      if (emulationActivity == null || nonBlocking)
       {
         new Handler(Looper.getMainLooper()).post(
                 () -> Toast.makeText(DolphinApplication.getAppContext(), text, Toast.LENGTH_LONG)

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/fragments/EmulationFragment.java

@@ -330,16 +330,6 @@ public final class EmulationFragment extends Fragment implements SurfaceHolder.C
         mSurface = null;
         Log.debug("[EmulationFragment] Surface destroyed.");
 
-        if (state != State.STOPPED && !NativeLibrary.IsShowingAlertMessage())
-        {
-          // In order to avoid dereferencing nullptr, we must not destroy the surface while booting
-          // the core, so wait here if necessary. An easy (but not 100% consistent) way to reach
-          // this method while the core is booting is by having landscape orientation lock enabled
-          // and starting emulation while the phone is in portrait mode, leading to the activity
-          // being recreated very soon after NativeLibrary.Run has been called.
-          NativeLibrary.WaitUntilDoneBooting();
-        }
-
         NativeLibrary.SurfaceDestroyed();
       }
     }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/overlay/InputOverlay.java

@@ -148,7 +148,7 @@ public final class InputOverlay extends SurfaceView implements OnTouchListener
   public void initTouchPointer()
   {
     // Check if we have all the data we need yet
-    boolean aspectRatioAvailable = NativeLibrary.IsRunning() && !NativeLibrary.IsBooting();
+    boolean aspectRatioAvailable = NativeLibrary.IsRunningAndStarted();
     if (!aspectRatioAvailable || mSurfacePosition == null)
       return;
 

Source/Android/jni/AndroidCommon/IDCache.cpp

@@ -222,7 +222,7 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved)
   const jclass native_library_class = env->FindClass("org/dolphinemu/dolphinemu/NativeLibrary");
   s_native_library_class = reinterpret_cast<jclass>(env->NewGlobalRef(native_library_class));
   s_display_alert_msg = env->GetStaticMethodID(s_native_library_class, "displayAlertMsg",
-                                               "(Ljava/lang/String;Ljava/lang/String;ZZ)Z");
+                                               "(Ljava/lang/String;Ljava/lang/String;ZZZ)Z");
   s_do_rumble = env->GetStaticMethodID(s_native_library_class, "rumble", "(ID)V");
   s_update_touch_pointer =
       env->GetStaticMethodID(s_native_library_class, "updateTouchPointer", "()V");

Source/Android/jni/MainAndroid.cpp

@@ -77,6 +77,12 @@ ANativeWindow* s_surf;
 // sequentially for access.
 std::mutex s_host_identity_lock;
 Common::Event s_update_main_frame_event;
+
+// This exists to prevent surfaces from being destroyed during the boot process,
+// as that can lead to the boot process dereferencing nullptr.
+std::mutex s_surface_lock;
+bool s_need_nonblocking_alert_msg;
+
 bool s_have_wm_user_stop = false;
 bool s_game_metadata_is_valid = false;
 }  // Anonymous namespace
@@ -159,9 +165,10 @@ static bool MsgAlert(const char* caption, const char* text, bool yes_no, Common:
   JNIEnv* env = IDCache::GetEnvForThread();
 
   // Execute the Java method.
-  jboolean result = env->CallStaticBooleanMethod(
-      IDCache::GetNativeLibraryClass(), IDCache::GetDisplayAlertMsg(), ToJString(env, caption),
-      ToJString(env, text), yes_no ? JNI_TRUE : JNI_FALSE, style == Common::MsgType::Warning);
+  jboolean result =
+      env->CallStaticBooleanMethod(IDCache::GetNativeLibraryClass(), IDCache::GetDisplayAlertMsg(),
+                                   ToJString(env, caption), ToJString(env, text), yes_no,
+                                   style == Common::MsgType::Warning, s_need_nonblocking_alert_msg);
 
   return result != JNI_FALSE;
 }
@@ -216,20 +223,15 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_StopEmulatio
   s_update_main_frame_event.Set();
 }
 
-JNIEXPORT jboolean JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_IsBooting(JNIEnv*, jclass)
-{
-  return static_cast<jboolean>(Core::IsBooting());
-}
-
-JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_WaitUntilDoneBooting(JNIEnv*,
-                                                                                         jclass)
-{
-  Core::WaitUntilDoneBooting();
-}
-
 JNIEXPORT jboolean JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_IsRunning(JNIEnv*, jclass)
 {
-  return Core::IsRunning();
+  return static_cast<jboolean>(Core::IsRunning());
+}
+
+JNIEXPORT jboolean JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_IsRunningAndStarted(JNIEnv*,
+                                                                                            jclass)
+{
+  return static_cast<jboolean>(Core::IsRunningAndStarted());
 }
 
 JNIEXPORT jboolean JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_onGamePadEvent(
@@ -391,6 +393,8 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SurfaceChang
                                                                                    jclass,
                                                                                    jobject surf)
 {
+  std::lock_guard<std::mutex> guard(s_surface_lock);
+
   s_surf = ANativeWindow_fromSurface(env, surf);
   if (s_surf == nullptr)
     __android_log_print(ANDROID_LOG_ERROR, DOLPHIN_TAG, "Error: Surface is null.");
@@ -402,6 +406,8 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SurfaceChang
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SurfaceDestroyed(JNIEnv*,
                                                                                      jclass)
 {
+  std::lock_guard<std::mutex> guard(s_surface_lock);
+
   if (g_renderer)
     g_renderer->ChangeSurface(nullptr);
 
@@ -480,7 +486,7 @@ static void Run(JNIEnv* env, const std::vector<std::string>& paths,
   ASSERT(!paths.empty());
   __android_log_print(ANDROID_LOG_INFO, DOLPHIN_TAG, "Running : %s", paths[0].c_str());
 
-  std::unique_lock<std::mutex> guard(s_host_identity_lock);
+  std::unique_lock<std::mutex> host_identity_guard(s_host_identity_lock);
 
   WiimoteReal::InitAdapterClass();
 
@@ -493,24 +499,41 @@ static void Run(JNIEnv* env, const std::vector<std::string>& paths,
   WindowSystemInfo wsi(WindowSystemType::Android, nullptr, s_surf, s_surf);
   wsi.render_surface_scale = GetRenderSurfaceScale(env);
 
-  // No use running the loop when booting fails
-  if (BootManager::BootCore(std::move(boot), wsi))
+  s_need_nonblocking_alert_msg = true;
+  std::unique_lock<std::mutex> surface_guard(s_surface_lock);
+
+  bool successful_boot = BootManager::BootCore(std::move(boot), wsi);
+  if (successful_boot)
   {
     ButtonManager::Init(SConfig::GetInstance().GetGameID());
+
     static constexpr int TIMEOUT = 10000;
     static constexpr int WAIT_STEP = 25;
     int time_waited = 0;
     // A Core::CORE_ERROR state would be helpful here.
-    while (!Core::IsRunning() && time_waited < TIMEOUT && !s_have_wm_user_stop)
+    while (!Core::IsRunningAndStarted())
     {
+      if (time_waited >= TIMEOUT || s_have_wm_user_stop)
+      {
+        successful_boot = false;
+        break;
+      }
+
       std::this_thread::sleep_for(std::chrono::milliseconds(WAIT_STEP));
       time_waited += WAIT_STEP;
     }
-    while (Core::IsRunning())
+  }
+
+  s_need_nonblocking_alert_msg = false;
+  surface_guard.unlock();
+
+  if (successful_boot)
+  {
+    while (Core::IsRunningAndStarted())
     {
-      guard.unlock();
+      host_identity_guard.unlock();
       s_update_main_frame_event.Wait();
-      guard.lock();
+      host_identity_guard.lock();
       Core::HostDispatchJobs();
     }
   }
@@ -518,7 +541,7 @@ static void Run(JNIEnv* env, const std::vector<std::string>& paths,
   s_game_metadata_is_valid = false;
   Core::Shutdown();
   ButtonManager::Shutdown();
-  guard.unlock();
+  host_identity_guard.unlock();
 
   if (s_surf)
   {

Source/Core/Core/Core.cpp

@@ -102,7 +102,6 @@ static bool s_is_stopping = false;
 static bool s_hardware_initialized = false;
 static bool s_is_started = false;
 static Common::Flag s_is_booting;
-static Common::Event s_done_booting;
 static std::thread s_emu_thread;
 static StateChangedCallbackFunc s_on_state_changed_callback;
 
@@ -175,11 +174,6 @@ void DisplayMessage(std::string message, int time_in_ms)
   OSD::AddMessage(std::move(message), time_in_ms);
 }
 
-bool IsBooting()
-{
-  return s_is_booting.IsSet() || !s_hardware_initialized;
-}
-
 bool IsRunning()
 {
   return (GetState() != State::Uninitialized || s_hardware_initialized) && !s_is_stopping;
@@ -249,7 +243,6 @@ bool Init(std::unique_ptr<BootParameters> boot, const WindowSystemInfo& wsi)
   g_video_backend->PrepareWindow(prepared_wsi);
 
   // Start the emu thread
-  s_done_booting.Reset();
   s_is_booting.Set();
   s_emu_thread = std::thread(EmuThread, std::move(boot), prepared_wsi);
   return true;
@@ -435,7 +428,6 @@ static void EmuThread(std::unique_ptr<BootParameters> boot, WindowSystemInfo wsi
     s_on_state_changed_callback(State::Starting);
   Common::ScopeGuard flag_guard{[] {
     s_is_booting.Clear();
-    s_done_booting.Set();
     s_is_started = false;
     s_is_stopping = false;
     s_wants_determinism = false;
@@ -568,7 +560,6 @@ static void EmuThread(std::unique_ptr<BootParameters> boot, WindowSystemInfo wsi
   // The hardware is initialized.
   s_hardware_initialized = true;
   s_is_booting.Clear();
-  s_done_booting.Set();
 
   // Set execution state to known values (CPU/FIFO/Audio Paused)
   CPU::Break();
@@ -692,12 +683,6 @@ State GetState()
   return State::Uninitialized;
 }
 
-void WaitUntilDoneBooting()
-{
-  if (IsBooting())
-    s_done_booting.Wait();
-}
-
 static std::string GenerateScreenshotFolderPath()
 {
   const std::string& gameId = SConfig::GetInstance().GetGameID();

Source/Core/Core/Core.h

@@ -99,7 +99,6 @@ void UndeclareAsCPUThread();
 
 std::string StopMessage(bool main_thread, std::string_view message);
 
-bool IsBooting();
 bool IsRunning();
 bool IsRunningAndStarted();       // is running and the CPU loop has been entered
 bool IsRunningInCurrentThread();  // this tells us whether we are running in the CPU thread.
@@ -111,7 +110,6 @@ bool WantsDeterminism();
 // [NOT THREADSAFE] For use by Host only
 void SetState(State state);
 State GetState();
-void WaitUntilDoneBooting();
 
 void SaveScreenShot();
 void SaveScreenShot(std::string_view name);