Core/Movie: Add ability to run code in Host context

EndPlayInput runs on the CPU thread so it can't directly call
UpdateWantDeterminism. PlayController also tries to ChangeDisc
from the CPU Thread which is also invalid. It now just pauses
execution and posts a request to the Host to fix it instead.

The Core itself also did dodgy things like PauseAndLock-ing
from the CPU Thread and SetState from EmuThread which have been
removed.

Source/Android/jni/MainAndroid.cpp

@@ -7,6 +7,7 @@
 #include <cstdlib>
 #include <jni.h>
 #include <memory>
+#include <mutex>
 #include <thread>
 #include <android/log.h>
 #include <android/native_window_jni.h>
@@ -65,13 +66,23 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved)
 void Host_NotifyMapLoaded() {}
 void Host_RefreshDSPDebuggerWindow() {}
 
+// The Core only supports using a single Host thread.
+// If multiple threads want to call host functions then they need to queue
+// sequentially for access.
+static std::mutex s_host_identity_lock;
 Common::Event updateMainFrameEvent;
 static bool s_have_wm_user_stop = false;
 void Host_Message(int Id)
 {
-	if (Id == WM_USER_STOP)
+	if (Id == WM_USER_JOB_DISPATCH)
+	{
+		updateMainFrameEvent.Set();
+	}
+	else if (Id == WM_USER_STOP)
 	{
 		s_have_wm_user_stop = true;
+		if (Core::IsRunning())
+			Core::QueueHostJob(&Core::Stop);
 	}
 }
 
@@ -393,15 +404,18 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SurfaceDestr
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_UnPauseEmulation(JNIEnv *env, jobject obj)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	Core::SetState(Core::CORE_RUN);
 }
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_PauseEmulation(JNIEnv *env, jobject obj)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	Core::SetState(Core::CORE_PAUSE);
 }
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_StopEmulation(JNIEnv *env, jobject obj)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	Core::SaveScreenShot("thumb");
 	Renderer::s_screenshotCompleted.WaitFor(std::chrono::seconds(2));
 	Core::Stop();
@@ -490,6 +504,7 @@ JNIEXPORT jboolean JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_Supports
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SaveScreenShot(JNIEnv *env, jobject obj)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	Core::SaveScreenShot();
 }
 
@@ -534,11 +549,13 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SetFilename(
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SaveState(JNIEnv *env, jobject obj, jint slot)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	State::Save(slot);
 }
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_LoadState(JNIEnv *env, jobject obj, jint slot)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	State::Load(slot);
 }
 
@@ -565,6 +582,7 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_CreateUserFo
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SetUserDirectory(JNIEnv *env, jobject obj, jstring jDirectory)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	std::string directory = GetJString(env, jDirectory);
 	g_set_userpath = directory;
 	UICommon::SetUserDirectory(directory);
@@ -577,6 +595,7 @@ JNIEXPORT jstring JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_GetUserDi
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SetProfiling(JNIEnv *env, jobject obj, jboolean enable)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	Core::SetState(Core::CORE_PAUSE);
 	JitInterface::ClearCache();
 	Profiler::g_ProfileBlocks = enable;
@@ -585,6 +604,7 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SetProfiling
 
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_WriteProfileResults(JNIEnv *env, jobject obj)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	std::string filename = File::GetUserPath(D_DUMP_IDX) + "Debug/profiler.txt";
 	File::CreateFullPath(filename);
 	JitInterface::WriteProfileResults(filename);
@@ -643,6 +663,7 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_SurfaceDestr
 }
 JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_RefreshWiimotes(JNIEnv *env, jobject obj)
 {
+	std::lock_guard<std::mutex> guard(s_host_identity_lock);
 	WiimoteReal::Refresh();
 }
 
@@ -656,6 +677,7 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_Run(JNIEnv *
 
 	RegisterMsgAlertHandler(&MsgAlert);
 
+	std::unique_lock<std::mutex> guard(s_host_identity_lock);
 	UICommon::SetUserDirectory(g_set_userpath);
 	UICommon::Init();
 
@@ -676,12 +698,16 @@ JNIEXPORT void JNICALL Java_org_dolphinemu_dolphinemu_NativeLibrary_Run(JNIEnv *
 		}
 		while (Core::IsRunning())
 		{
+			guard.unlock();
 			updateMainFrameEvent.Wait();
+			guard.lock();
+			Core::HostDispatchJobs();
 		}
 	}
 
 	Core::Shutdown();
 	UICommon::Shutdown();
+	guard.unlock();
 
 	if (surf)
 	{