Android: Use Java thread for emulation thread

android/app/src/cpp/android_host_interface.cpp

@@ -265,39 +265,20 @@ bool AndroidHostInterface::IsEmulationThreadPaused() const
   return System::IsValid() && System::IsPaused();
 }
 
-bool AndroidHostInterface::StartEmulationThread(jobject emulation_activity, ANativeWindow* initial_surface,
-                                                SystemBootParameters boot_params, bool resume_state)
-{
-  Assert(!IsEmulationThreadRunning());
-
-  emulation_activity = AndroidHelpers::GetJNIEnv()->NewGlobalRef(emulation_activity);
-
-  Log_DevPrintf("Starting emulation thread...");
-  m_emulation_thread_stop_request.store(false);
-  m_emulation_thread = std::thread(&AndroidHostInterface::EmulationThreadEntryPoint, this, emulation_activity,
-                                   initial_surface, std::move(boot_params), resume_state);
-  return true;
-}
-
 void AndroidHostInterface::PauseEmulationThread(bool paused)
 {
   Assert(IsEmulationThreadRunning());
   RunOnEmulationThread([this, paused]() { PauseSystem(paused); });
 }
 
-void AndroidHostInterface::StopEmulationThread()
+void AndroidHostInterface::StopEmulationThreadLoop()
 {
   if (!IsEmulationThreadRunning())
     return;
 
-  Log_InfoPrint("Stopping emulation thread...");
-  {
-    std::unique_lock<std::mutex> lock(m_mutex);
-    m_emulation_thread_stop_request.store(true);
-    m_sleep_cv.notify_one();
-  }
-  m_emulation_thread.join();
-  Log_InfoPrint("Emulation thread stopped");
+  std::unique_lock<std::mutex> lock(m_mutex);
+  m_emulation_thread_stop_request.store(true);
+  m_sleep_cv.notify_one();
 }
 
 void AndroidHostInterface::RunOnEmulationThread(std::function<void()> function, bool blocking)
@@ -329,18 +310,19 @@ void AndroidHostInterface::RunOnEmulationThread(std::function<void()> function,
   m_mutex.unlock();
 }
 
-void AndroidHostInterface::EmulationThreadEntryPoint(jobject emulation_activity, ANativeWindow* initial_surface,
+void AndroidHostInterface::EmulationThreadEntryPoint(JNIEnv* env, jobject emulation_activity, jobject surface,
                                                      SystemBootParameters boot_params, bool resume_state)
 {
-  JNIEnv* thread_env;
-  if (s_jvm->AttachCurrentThread(&thread_env, nullptr) != JNI_OK)
+  ANativeWindow* native_surface = ANativeWindow_fromSurface(env, surface);
+  if (!native_surface)
   {
-    ReportError("Failed to attach JNI to thread");
+    Log_ErrorPrint("ANativeWindow_fromSurface() returned null");
+    env->CallVoidMethod(m_emulation_activity_object, s_EmulationActivity_method_onEmulationStopped);
     return;
   }
 
   CreateImGuiContext();
-  m_surface = initial_surface;
+  m_surface = native_surface;
   m_emulation_activity_object = emulation_activity;
   ApplySettings(true);
 
@@ -358,35 +340,36 @@ void AndroidHostInterface::EmulationThreadEntryPoint(jobject emulation_activity,
     boot_result = BootSystem(boot_params);
   }
 
-  if (!boot_result)
+  if (boot_result)
   {
-    ReportFormattedError("Failed to boot system on emulation thread (file:%s).", boot_params.filename.c_str());
-    DestroyImGuiContext();
-    thread_env->CallVoidMethod(m_emulation_activity_object, s_EmulationActivity_method_onEmulationStopped);
-    thread_env->DeleteGlobalRef(m_emulation_activity_object);
-    m_emulation_activity_object = {};
-    s_jvm->DetachCurrentThread();
-    return;
-  }
+    // System is ready to go.
+    EmulationThreadLoop(env);
 
-  // System is ready to go.
-  thread_env->CallVoidMethod(m_emulation_activity_object, s_EmulationActivity_method_onEmulationStarted);
-  EmulationThreadLoop();
+    if (g_settings.save_state_on_exit)
+      SaveResumeSaveState();
 
-  thread_env->CallVoidMethod(m_emulation_activity_object, s_EmulationActivity_method_onEmulationStopped);
+    PowerOffSystem();
+  }
+  else
+  {
+    ReportFormattedError("Failed to boot system on emulation thread (file:%s).", boot_params.filename.c_str());
+  }
 
-  if (g_settings.save_state_on_exit)
-    SaveResumeSaveState();
+  env->CallVoidMethod(m_emulation_activity_object, s_EmulationActivity_method_onEmulationStopped);
 
-  PowerOffSystem();
   DestroyImGuiContext();
-  thread_env->DeleteGlobalRef(m_emulation_activity_object);
   m_emulation_activity_object = {};
-  s_jvm->DetachCurrentThread();
 }
 
-void AndroidHostInterface::EmulationThreadLoop()
+void AndroidHostInterface::EmulationThreadLoop(JNIEnv* env)
 {
+  {
+    std::unique_lock<std::mutex> lock(m_mutex);
+    m_emulation_thread_running.store(true);
+  }
+
+  env->CallVoidMethod(m_emulation_activity_object, s_EmulationActivity_method_onEmulationStarted);
+
   for (;;)
   {
     // run any events
@@ -408,7 +391,11 @@ void AndroidHostInterface::EmulationThreadLoop()
         }
 
         if (m_emulation_thread_stop_request.load())
+        {
+          m_emulation_thread_running.store(false);
+          m_emulation_thread_stop_request.store(false);
           return;
+        }
 
         if (System::IsPaused())
         {
@@ -475,11 +462,12 @@ bool AndroidHostInterface::AcquireHostDisplay()
       !display->InitializeRenderDevice(GetShaderCacheBasePath(), g_settings.gpu_use_debug_device,
                                        g_settings.gpu_threaded_presentation))
   {
-    ReportError("Failed to acquire host display.");
     display->DestroyRenderDevice();
     return false;
   }
 
+  // The alignement was set prior to booting.
+  display->SetDisplayAlignment(m_display_alignment);
   m_display = std::move(display);
 
   if (!CreateHostDisplayResources())
@@ -591,6 +579,13 @@ void AndroidHostInterface::SurfaceChanged(ANativeWindow* surface, int format, in
   }
 }
 
+void AndroidHostInterface::SetDisplayAlignment(HostDisplay::Alignment alignment)
+{
+  m_display_alignment = alignment;
+  if (m_display)
+    m_display->SetDisplayAlignment(alignment);
+}
+
 void AndroidHostInterface::CreateImGuiContext()
 {
   ImGui::CreateContext();
@@ -956,28 +951,21 @@ DEFINE_JNI_ARGS_METHOD(jboolean, AndroidHostInterface_isEmulationThreadRunning,
   return AndroidHelpers::GetNativeClass(env, obj)->IsEmulationThreadRunning();
 }
 
-DEFINE_JNI_ARGS_METHOD(jboolean, AndroidHostInterface_startEmulationThread, jobject obj, jobject emulationActivity,
+DEFINE_JNI_ARGS_METHOD(void, AndroidHostInterface_runEmulationThread, jobject obj, jobject emulationActivity,
                        jobject surface, jstring filename, jboolean resume_state, jstring state_filename)
 {
-  ANativeWindow* native_surface = ANativeWindow_fromSurface(env, surface);
-  if (!native_surface)
-  {
-    Log_ErrorPrint("ANativeWindow_fromSurface() returned null");
-    return false;
-  }
-
   std::string state_filename_str = AndroidHelpers::JStringToString(env, state_filename);
 
   SystemBootParameters boot_params;
   boot_params.filename = AndroidHelpers::JStringToString(env, filename);
 
-  return AndroidHelpers::GetNativeClass(env, obj)->StartEmulationThread(emulationActivity, native_surface,
-                                                                        std::move(boot_params), resume_state);
+  AndroidHelpers::GetNativeClass(env, obj)->EmulationThreadEntryPoint(env, emulationActivity, surface,
+                                                                      std::move(boot_params), resume_state);
 }
 
-DEFINE_JNI_ARGS_METHOD(void, AndroidHostInterface_stopEmulationThread, jobject obj)
+DEFINE_JNI_ARGS_METHOD(void, AndroidHostInterface_stopEmulationThreadLoop, jobject obj)
 {
-  AndroidHelpers::GetNativeClass(env, obj)->StopEmulationThread();
+  AndroidHelpers::GetNativeClass(env, obj)->StopEmulationThreadLoop();
 }
 
 DEFINE_JNI_ARGS_METHOD(void, AndroidHostInterface_surfaceChanged, jobject obj, jobject surface, jint format, jint width,
@@ -1310,7 +1298,7 @@ DEFINE_JNI_ARGS_METHOD(void, AndroidHostInterface_setDisplayAlignment, jobject o
 {
   AndroidHostInterface* hi = AndroidHelpers::GetNativeClass(env, obj);
   hi->RunOnEmulationThread(
-    [hi, alignment]() { hi->GetDisplay()->SetDisplayAlignment(static_cast<HostDisplay::Alignment>(alignment)); });
+    [hi, alignment]() { hi->SetDisplayAlignment(static_cast<HostDisplay::Alignment>(alignment)); }, false);
 }
 
 DEFINE_JNI_ARGS_METHOD(bool, AndroidHostInterface_hasSurface, jobject obj)

android/app/src/cpp/android_host_interface.h

@@ -3,6 +3,7 @@
 #include "common/byte_stream.h"
 #include "common/event.h"
 #include "common/progress_callback.h"
+#include "core/host_display.h"
 #include "frontend-common/common_host_interface.h"
 #include <array>
 #include <atomic>
@@ -38,15 +39,17 @@ public:
   float GetFloatSettingValue(const char* section, const char* key, float default_value = 0.0f) override;
   std::unique_ptr<ByteStream> OpenPackageFile(const char* path, u32 flags) override;
 
-  bool IsEmulationThreadRunning() const { return m_emulation_thread.joinable(); }
+  bool IsEmulationThreadRunning() const { return m_emulation_thread_running.load(); }
   bool IsEmulationThreadPaused() const;
-  bool StartEmulationThread(jobject emulation_activity, ANativeWindow* initial_surface,
-                            SystemBootParameters boot_params, bool resume_state);
   void RunOnEmulationThread(std::function<void()> function, bool blocking = false);
   void PauseEmulationThread(bool paused);
-  void StopEmulationThread();
+  void StopEmulationThreadLoop();
+
+  void EmulationThreadEntryPoint(JNIEnv* env, jobject emulation_activity, jobject initial_surface,
+                                 SystemBootParameters boot_params, bool resume_state);
 
   void SurfaceChanged(ANativeWindow* surface, int format, int width, int height);
+  void SetDisplayAlignment(HostDisplay::Alignment alignment);
 
   void SetControllerType(u32 index, std::string_view type_name);
   void SetControllerButtonState(u32 index, s32 button_code, bool pressed);
@@ -79,9 +82,7 @@ protected:
   void OnRunningGameChanged() override;
 
 private:
-  void EmulationThreadEntryPoint(jobject emulation_activity, ANativeWindow* initial_surface,
-                                 SystemBootParameters boot_params, bool resume_state);
-  void EmulationThreadLoop();
+  void EmulationThreadLoop(JNIEnv* env);
 
   void CreateImGuiContext();
   void DestroyImGuiContext();
@@ -102,8 +103,10 @@ private:
   std::deque<std::function<void()>> m_callback_queue;
   std::atomic_bool m_callbacks_outstanding{false};
 
-  std::thread m_emulation_thread;
   std::atomic_bool m_emulation_thread_stop_request{false};
+  std::atomic_bool m_emulation_thread_running{false};
+
+  HostDisplay::Alignment m_display_alignment = HostDisplay::Alignment::Center;
 
   u64 m_last_vibration_update_time = 0;
   bool m_last_vibration_state = false;
@@ -111,11 +114,13 @@ private:
 };
 
 namespace AndroidHelpers {
+
 JNIEnv* GetJNIEnv();
 AndroidHostInterface* GetNativeClass(JNIEnv* env, jobject obj);
 std::string JStringToString(JNIEnv* env, jstring str);
 std::unique_ptr<GrowableMemoryByteStream> ReadInputStreamToMemory(JNIEnv* env, jobject obj, u32 chunk_size = 65536);
 jclass GetStringClass();
+
 } // namespace AndroidHelpers
 
 template<typename T>

android/app/src/main/java/com/github/stenzek/duckstation/AndroidHostInterface.java

@@ -4,6 +4,7 @@ import android.content.Context;
 import android.content.SharedPreferences;
 import android.content.res.AssetManager;
 import android.os.Environment;
+import android.os.Process;
 import android.util.Log;
 import android.view.Surface;
 import android.widget.Toast;
@@ -20,12 +21,6 @@ public class AndroidHostInterface {
     private long mNativePointer;
     private Context mContext;
 
-    static public native String getScmVersion();
-
-    static public native String getFullScmVersion();
-
-    static public native AndroidHostInterface create(Context context, String userDirectory);
-
     public AndroidHostInterface(Context context) {
         this.mContext = context;
     }
@@ -46,15 +41,21 @@ public class AndroidHostInterface {
         }
     }
 
+    static public native String getScmVersion();
+
+    static public native String getFullScmVersion();
+
+    static public native AndroidHostInterface create(Context context, String userDirectory);
+
     public native boolean isEmulationThreadRunning();
 
-    public native boolean startEmulationThread(EmulationActivity emulationActivity, Surface surface, String filename, boolean resumeState, String state_filename);
+    public native boolean runEmulationThread(EmulationActivity emulationActivity, Surface surface, String filename, boolean resumeState, String state_filename);
 
     public native boolean isEmulationThreadPaused();
 
     public native void pauseEmulationThread(boolean paused);
 
-    public native void stopEmulationThread();
+    public native void stopEmulationThreadLoop();
 
     public native boolean hasSurface();
 

android/app/src/main/java/com/github/stenzek/duckstation/EmulationActivity.java

@@ -108,12 +108,24 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
         });
     }
 
+    private EmulationThread mEmulationThread;
+
+    private void stopEmulationThread() {
+        if (mEmulationThread == null)
+            return;
+
+        mEmulationThread.stopAndJoin();
+        mEmulationThread = null;
+    }
+
     public void onEmulationStarted() {
+        runOnUiThread(() -> {
+            updateOrientation();
+        });
     }
 
     public void onEmulationStopped() {
         runOnUiThread(() -> {
-            AndroidHostInterface.getInstance().stopEmulationThread();
             if (!mWasDestroyed && !mStopRequested)
                 finish();
         });
@@ -159,7 +171,7 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
     @Override
     public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
         // Once we get a surface, we can boot.
-        if (AndroidHostInterface.getInstance().isEmulationThreadRunning()) {
+        if (mEmulationThread != null) {
             AndroidHostInterface.getInstance().surfaceChanged(holder.getSurface(), format, width, height);
             updateOrientation();
 
@@ -175,9 +187,7 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
         final boolean resumeState = getIntent().getBooleanExtra("resumeState", false);
         final String bootSaveStatePath = getIntent().getStringExtra("saveStatePath");
 
-        AndroidHostInterface.getInstance().startEmulationThread(this, holder.getSurface(), bootPath, resumeState, bootSaveStatePath);
-        updateRequestedOrientation();
-        updateOrientation();
+        mEmulationThread = EmulationThread.create(this, holder.getSurface(), bootPath, resumeState, bootSaveStatePath);
     }
 
     @Override
@@ -219,6 +229,10 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
         }
         mContentView.requestFocus();
 
+        // Sort out rotation.
+        updateRequestedOrientation();
+        updateOrientation();
+
         // Hook up controller input.
         updateControllers();
         registerInputDeviceListener();
@@ -240,9 +254,9 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
     protected void onDestroy() {
         super.onDestroy();
         Log.i("EmulationActivity", "OnStop");
-        if (AndroidHostInterface.getInstance().isEmulationThreadRunning()) {
+        if (mEmulationThread != null) {
             mWasDestroyed = true;
-            AndroidHostInterface.getInstance().stopEmulationThread();
+            stopEmulationThread();
         }
 
         unregisterInputDeviceListener();
@@ -317,9 +331,6 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
     }
 
     private void updateOrientation(int newOrientation) {
-        if (!AndroidHostInterface.getInstance().isEmulationThreadRunning())
-            return;
-
         if (newOrientation == Configuration.ORIENTATION_PORTRAIT)
             AndroidHostInterface.getInstance().setDisplayAlignment(AndroidHostInterface.DISPLAY_ALIGNMENT_TOP_OR_LEFT);
         else

android/app/src/main/java/com/github/stenzek/duckstation/EmulationThread.java

@@ -0,0 +1,53 @@
+package com.github.stenzek.duckstation;
+
+import android.os.Process;
+import android.util.Log;
+import android.view.Surface;
+
+import androidx.annotation.NonNull;
+
+public class EmulationThread extends Thread {
+    private EmulationActivity emulationActivity;
+    private Surface surface;
+    private String filename;
+    private boolean resumeState;
+    private String stateFilename;
+
+    private EmulationThread(EmulationActivity emulationActivity, Surface surface, String filename, boolean resumeState, String stateFilename) {
+        super("EmulationThread");
+        this.emulationActivity = emulationActivity;
+        this.surface = surface;
+        this.filename = filename;
+        this.resumeState = resumeState;
+        this.stateFilename = stateFilename;
+    }
+
+    public static EmulationThread create(EmulationActivity emulationActivity, Surface surface, String filename, boolean resumeState, String stateFilename) {
+        Log.i("EmulationThread", String.format("Starting emulation thread (%s)...", filename));
+
+        EmulationThread thread = new EmulationThread(emulationActivity, surface, filename, resumeState, stateFilename);
+        thread.start();
+        return thread;
+    }
+
+    @Override
+    public void run() {
+        try {
+            Process.setThreadPriority(Process.THREAD_PRIORITY_MORE_FAVORABLE);
+        } catch (Exception e) {
+            Log.i("EmulationThread", "Failed to set priority for emulation thread: " + e.getMessage());
+        }
+
+        AndroidHostInterface.getInstance().runEmulationThread(emulationActivity, surface, filename, resumeState, stateFilename);
+        Log.i("EmulationThread", "Emulation thread exiting.");
+    }
+
+    public void stopAndJoin() {
+        AndroidHostInterface.getInstance().stopEmulationThreadLoop();
+        try {
+            join();
+        } catch (InterruptedException e) {
+            Log.i("EmulationThread", "join() interrupted: " + e.getMessage());
+        }
+    }
+}