Strict mode checking - no way to forget detaching now.

And if we forget to attach, boom. Hopefully I caught all of them.

Common/File/PathBrowser.cpp

@@ -141,6 +141,8 @@ void PathBrowser::HandlePath() {
 	pendingThread_ = std::thread([&] {
 		SetCurrentThreadName("PathBrowser");
 
+		AndroidJNIThreadContext jniContext;  // destructor detaches
+
 		std::unique_lock<std::mutex> guard(pendingLock_);
 		std::vector<File::FileInfo> results;
 		Path lastPath("NONSENSE THAT WONT EQUAL A PATH");
@@ -177,8 +179,6 @@ void PathBrowser::HandlePath() {
 				ready_ = true;
 			}
 		}
-
-		DetachThreadFromJNI();
 	});
 }
 

Common/Net/HTTPClient.cpp

@@ -526,6 +526,9 @@ std::string Download::RedirectLocation(const std::string &baseUrl) {
 
 void Download::Do() {
 	SetCurrentThreadName("Downloader::Do");
+
+	AndroidJNIThreadContext jniContext;
+
 	resultCode_ = 0;
 
 	std::string downloadURL = url_;

Common/Thread/ThreadManager.cpp

@@ -133,6 +133,10 @@ static void WorkerThreadFunc(GlobalThreadContext *global, ThreadContext *thread)
 	}
 	SetCurrentThreadName(thread->name);
 
+	if (thread->type == TaskType::IO_BLOCKING) {
+		AttachThreadToJNI();
+	}
+
 	const bool isCompute = thread->type == TaskType::CPU_COMPUTE;
 	const auto global_queue_size = [isCompute, &global]() -> int {
 		return isCompute ? global->compute_queue_size.load() : global->io_queue_size.load();
@@ -187,7 +191,9 @@ static void WorkerThreadFunc(GlobalThreadContext *global, ThreadContext *thread)
 	}
 
 	// In case it got attached to JNI, detach it. Don't think this has any side effects if called redundantly.
-	DetachThreadFromJNI();
+	if (thread->type == TaskType::IO_BLOCKING) {
+		DetachThreadFromJNI();
+	}
 }
 
 void ThreadManager::Init(int numRealCores, int numLogicalCoresPerCpu) {

Common/Thread/ThreadUtil.cpp

@@ -67,6 +67,15 @@ static EXCEPTION_DISPOSITION NTAPI ignore_handler(EXCEPTION_RECORD *rec,
 }
 #endif
 
+void AttachThreadToJNI() {
+#if PPSSPP_PLATFORM(ANDROID)
+	Android_AttachThreadToJNI();
+#else
+	// Do nothing
+#endif
+}
+
+
 void DetachThreadFromJNI() {
 #if PPSSPP_PLATFORM(ANDROID)
 	Android_DetachThreadFromJNI();

Common/Thread/ThreadUtil.h

@@ -14,13 +14,20 @@ const char *GetCurrentThreadName();
 // exactly what it is is badly specified and not useful for anything.
 int GetCurrentThreadIdForDebug();
 
+// When you know that a thread potentially will make JNI calls, call this after setting its name.
+void AttachThreadToJNI();
+
 // Call when leaving threads. On Android, calls DetachCurrentThread.
 // Threads that use scoped storage I/O end up attached as JNI threads, and will thus
 // need this in order to follow the rules correctly. Some devices seem to enforce this.
 void DetachThreadFromJNI();
 
+// Utility to call the above two functions.
 class AndroidJNIThreadContext {
 public:
+	AndroidJNIThreadContext() {
+		AttachThreadToJNI();
+	}
 	~AndroidJNIThreadContext() {
 		DetachThreadFromJNI();
 	}

Core/Config.cpp

@@ -1736,6 +1736,9 @@ void Config::RemoveRecent(const std::string &file) {
 void Config::CleanRecent() {
 	private_->SetRecentIsosThread([this] {
 		SetCurrentThreadName("RecentISOs");
+
+		AndroidJNIThreadContext jniContext;  // destructor detaches
+
 		double startTime = time_now_d();
 
 		std::lock_guard<std::mutex> guard(private_->recentIsosLock);
@@ -1766,8 +1769,6 @@ void Config::CleanRecent() {
 
 		INFO_LOG(SYSTEM, "CleanRecent took %0.2f", time_now_d() - startTime);
 		recentIsos = cleanedRecent;
-
-		DetachThreadFromJNI();
 	});
 }
 

Core/FileLoaders/CachingFileLoader.cpp

@@ -269,6 +269,8 @@ void CachingFileLoader::StartReadAhead(s64 pos) {
 	aheadThread_ = std::thread([this, pos] {
 		SetCurrentThreadName("FileLoaderReadAhead");
 
+		AndroidJNIThreadContext jniContext;
+
 		std::unique_lock<std::recursive_mutex> guard(blocksMutex_);
 		s64 cacheStartPos = pos >> BLOCK_SHIFT;
 		s64 cacheEndPos = cacheStartPos + BLOCK_READAHEAD - 1;

Core/FileLoaders/RamCachingFileLoader.cpp

@@ -227,6 +227,8 @@ void RamCachingFileLoader::StartReadAhead(s64 pos) {
 	aheadThread_ = std::thread([this] {
 		SetCurrentThreadName("FileLoaderReadAhead");
 
+		AndroidJNIThreadContext jniContext;
+
 		while (aheadRemaining_ != 0 && !aheadCancel_) {
 			// Where should we look?
 			const u32 cacheStartPos = NextAheadBlock();

Core/HLE/sceIo.cpp

@@ -579,6 +579,7 @@ static void __IoAsyncEndCallback(SceUID threadID, SceUID prevCallbackId) {
 
 static void __IoManagerThread() {
 	SetCurrentThreadName("IO");
+	AndroidJNIThreadContext jniContext;
 	while (ioManagerThreadEnabled && coreState != CORE_BOOT_ERROR && coreState != CORE_RUNTIME_ERROR && coreState != CORE_POWERDOWN) {
 		ioManager.RunEventsUntil(CoreTiming::GetTicks() + msToCycles(1000));
 	}

Core/HW/MemoryStick.cpp

@@ -19,8 +19,10 @@
 #include <condition_variable>
 #include <mutex>
 #include <thread>
+
 #include "Common/Serialize/Serializer.h"
 #include "Common/Serialize/SerializeFuncs.h"
+#include "Common/Thread/ThreadUtil.h"
 #include "Core/Config.h"
 #include "Core/CoreTiming.h"
 #include "Core/Compatibility.h"
@@ -97,6 +99,10 @@ static void MemoryStick_CalcInitialFree() {
 	std::unique_lock<std::mutex> guard(freeCalcMutex);
 	freeCalcStatus = FreeCalcStatus::RUNNING;
 	freeCalcThread = std::thread([] {
+		SetCurrentThreadName("CalcInitialFree");
+
+		AndroidJNIThreadContext jniContext;
+
 		memstickInitialFree = pspFileSystem.FreeSpace("ms0:/") + pspFileSystem.ComputeRecursiveDirectorySize("ms0:/PSP/SAVEDATA/");
 
 		std::unique_lock<std::mutex> guard(freeCalcMutex);

Core/PSPLoaders.cpp

@@ -307,7 +307,7 @@ bool Load_PSP_ISO(FileLoader *fileLoader, std::string *error_string) {
 	//in case we didn't go through EmuScreen::boot
 	g_Config.loadGameConfig(id, g_paramSFO.GetValueString("TITLE"));
 	host->SendUIMessage("config_loaded", "");
-	INFO_LOG(LOADER,"Loading %s...", bootpath.c_str());
+	INFO_LOG(LOADER, "Loading %s...", bootpath.c_str());
 
 	PSPLoaders_Shutdown();
 	// Note: this thread reads the game binary, loads caches, and links HLE while UI spins.
@@ -319,6 +319,8 @@ bool Load_PSP_ISO(FileLoader *fileLoader, std::string *error_string) {
 		if (coreState != CORE_POWERUP)
 			return;
 
+		AndroidJNIThreadContext jniContext;
+
 		PSP_SetLoading("Loading executable...");
 		// TODO: We can't use the initial error_string pointer.
 		bool success = __KernelLoadExec(bootpath.c_str(), 0, &PSP_CoreParameter().errorString);
@@ -455,6 +457,8 @@ bool Load_PSP_ELF_PBP(FileLoader *fileLoader, std::string *error_string) {
 		if (coreState != CORE_POWERUP)
 			return;
 
+		AndroidJNIThreadContext jniContext;
+
 		bool success = __KernelLoadExec(finalName.c_str(), 0, &PSP_CoreParameter().errorString);
 		if (success && coreState == CORE_POWERUP) {
 			coreState = PSP_CoreParameter().startBreak ? CORE_STEPPING : CORE_RUNNING;
@@ -479,6 +483,8 @@ bool Load_PSP_GE_Dump(FileLoader *fileLoader, std::string *error_string) {
 		if (coreState != CORE_POWERUP)
 			return;
 
+		AndroidJNIThreadContext jniContext;
+
 		bool success = __KernelLoadGEDump("disc0:/data.ppdmp", &PSP_CoreParameter().errorString);
 		if (success && coreState == CORE_POWERUP) {
 			coreState = PSP_CoreParameter().startBreak ? CORE_STEPPING : CORE_RUNNING;

Core/Reporting.cpp

@@ -111,6 +111,8 @@ namespace Reporting
 	static int CalculateCRCThread() {
 		SetCurrentThreadName("ReportCRC");
 
+		AndroidJNIThreadContext jniContext;
+
 		FileLoader *fileLoader = ResolveFileLoaderTarget(ConstructFileLoader(crcFilename));
 		BlockDevice *blockDevice = constructBlockDevice(fileLoader);
 

Core/SaveState.cpp

@@ -164,6 +164,9 @@ namespace SaveState
 				compressThread_.join();
 			compressThread_ = std::thread([=]{
 				SetCurrentThreadName("SaveStateCompress");
+
+				AndroidJNIThreadContext jniContext;
+
 				Compress(*result, *state, *base);
 			});
 		}

Core/WebServer.cpp

@@ -314,6 +314,8 @@ static void ForwardDebuggerRequest(const http::Request &request) {
 static void ExecuteWebServer() {
 	SetCurrentThreadName("HTTPServer");
 
+	AndroidJNIThreadContext context;  // Destructor detaches.
+
 	auto http = new http::Server(new NewThreadExecutor());
 	http->RegisterHandler("/", &HandleListing);
 	// This lists all the (current) recent ISOs.

UI/RemoteISOScreen.cpp

@@ -30,6 +30,7 @@
 #include "Common/Net/HTTPClient.h"
 #include "Common/Net/Resolve.h"
 #include "Common/Net/URL.h"
+#include "Common/Thread/ThreadUtil.h"
 
 #include "Common/File/PathBrowser.h"
 #include "Common/Data/Format/JSONReader.h"
@@ -366,6 +367,7 @@ RemoteISOConnectScreen::RemoteISOConnectScreen() {
 	scanAborted = false;
 
 	scanThread_ = new std::thread([](RemoteISOConnectScreen *thiz) {
+		SetCurrentThreadName("RemoteISOScan");
 		thiz->ExecuteScan();
 	}, this);
 }

android/jni/app-android.cpp

@@ -236,17 +236,7 @@ void AndroidLogger::Log(const LogMessage &message) {
 JNIEnv* getEnv() {
 	JNIEnv *env;
 	int status = gJvm->GetEnv((void**)&env, JNI_VERSION_1_6);
-	if (status < 0) {
-		// TODO: We should have a version of getEnv that doesn't allow auto-attach.
-		INFO_LOG(SYSTEM, "Thread '%s' not attached to JVM, attaching.", GetCurrentThreadName());
-		JavaVMAttachArgs args{};
-		args.version = JNI_VERSION_1_6;
-		args.name = GetCurrentThreadName();
-		status = gJvm->AttachCurrentThread(&env, &args);
-		if (status < 0) {
-			return nullptr;
-		}
-	}
+	_assert_msg_(status >= 0, "'%s': Can only call getEnv if you've attached the thread already!", GetCurrentThreadName());
 	return env;
 }
 
@@ -270,9 +260,31 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *pjvm, void *reserved) {
 	return JNI_VERSION_1_6;
 }
 
+void Android_AttachThreadToJNI() {
+	JNIEnv *env;
+	int status = gJvm->GetEnv((void **)&env, JNI_VERSION_1_6);
+	if (status < 0) {
+		// TODO: We should have a version of getEnv that doesn't allow auto-attach.
+		INFO_LOG(SYSTEM, "Attaching thread '%s' (not already attached) to JNI.", GetCurrentThreadName());
+		JavaVMAttachArgs args{};
+		args.version = JNI_VERSION_1_6;
+		args.name = GetCurrentThreadName();
+		status = gJvm->AttachCurrentThread(&env, &args);
+
+		if (status < 0) {
+			// bad, but wh
+		}
+	} else {
+		WARN_LOG(SYSTEM, "Thread %s was already attached to JNI.", GetCurrentThreadName());
+	}
+}
+
 void Android_DetachThreadFromJNI() {
-	INFO_LOG(SYSTEM, "Detaching thread from JNI: '%s'", GetCurrentThreadName());
-	gJvm->DetachCurrentThread();
+	if (gJvm->DetachCurrentThread() == JNI_OK) {
+		INFO_LOG(SYSTEM, "Detached thread from JNI: '%s'", GetCurrentThreadName());
+	} else {
+		WARN_LOG(SYSTEM, "Failed to detach thread '%s' from JNI - never attached?", GetCurrentThreadName());
+	}
 }
 
 // Only used in OpenGL mode.

android/jni/app-android.h

@@ -27,6 +27,7 @@ public:
 };
 #endif
 
+void Android_AttachThreadToJNI();
 void Android_DetachThreadFromJNI();
 
 #endif