ipc/android: Avoid deadlock on Android

src/xrt/auxiliary/CMakeLists.txt

@@ -12,6 +12,8 @@ set(ANDROID_SOURCE_FILES
 	android/android_globals.h
 	android/android_load_class.cpp
 	android/android_load_class.hpp
+	android/android_looper.c
+	android/android_looper.h
 	android/org.freedesktop.monado.auxiliary.cpp
 	android/org.freedesktop.monado.auxiliary.hpp
 	android/org.freedesktop.monado.auxiliary.impl.hpp
@@ -320,10 +322,13 @@ endif()
 
 
 if(ANDROID)
+	add_library(android_app_glue STATIC
+		${ANDROID_NDK}/sources/android/native_app_glue/android_native_app_glue.c)
+	target_include_directories(android_app_glue PUBLIC ${ANDROID_NDK}/sources/android/native_app_glue)
 	add_library(aux_android STATIC ${ANDROID_SOURCE_FILES})
 	target_link_libraries(aux_android
 		PUBLIC aux_util
-		PRIVATE ${ANDROID_LIBRARY} ${ANDROID_LOG_LIBRARY} xrt-external-jni-wrap xrt-external-jnipp
+		PRIVATE ${ANDROID_LIBRARY} ${ANDROID_LOG_LIBRARY} xrt-external-jni-wrap xrt-external-jnipp android_app_glue
 		)
 	target_link_libraries(aux_vk PUBLIC aux_android)
 endif()

src/xrt/auxiliary/android/android_looper.c

@@ -0,0 +1,31 @@
+// Copyright 2021, Qualcomm Innovation Center, Inc.
+// SPDX-License-Identifier: BSL-1.0
+/*!
+ * @file
+ * @brief Implementation of android looper functions.
+ * @author Jarvis Huang
+ * @ingroup aux_android
+ */
+
+#include "android_looper.h"
+
+#include "util/u_logging.h"
+
+#include <android_native_app_glue.h>
+#include <android/looper.h>
+
+void
+android_looper_poll_until_activity_resumed()
+{
+	struct android_poll_source *source;
+	// Can we assume that activity already resumed if polling is failed?
+	while (ALooper_pollAll(-1, NULL, NULL, (void **)&source) == LOOPER_ID_MAIN) {
+		if (source) {
+			source->process(source->app, source);
+			if (source->app->activityState == APP_CMD_RESUME && source->app->window) {
+				U_LOG_I("Activity is in resume state and window is ready now");
+				break;
+			}
+		}
+	}
+}

src/xrt/auxiliary/android/android_looper.h

@@ -0,0 +1,30 @@
+// Copyright 2021, Qualcomm Innovation Center, Inc.
+// SPDX-License-Identifier: BSL-1.0
+/*!
+ * @file
+ * @brief Utility functions for android looper.
+ * @author Jarvis Huang
+ * @ingroup aux_android
+ */
+
+#pragma once
+
+#ifdef XRT_OS_ANDROID
+
+#include <cstdbool>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*!
+ * Poll the looper until activity is in resume state.
+ */
+void
+android_looper_poll_until_activity_resumed();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // XRT_OS_ANDROID

src/xrt/ipc/android/ipc_client_android.cpp

@@ -10,13 +10,17 @@
 #include "ipc_client_android.h"
 
 #include "org.freedesktop.monado.ipc.hpp"
-#include "wrap/android.app.h"
-
 
 #include "xrt/xrt_config_android.h"
-#include "android/android_load_class.hpp"
 #include "util/u_logging.h"
 
+#include "android/android_load_class.hpp"
+#include "android/android_looper.h"
+
+#include "wrap/android.app.h"
+
+#include <android/api-level.h>
+
 using wrap::android::app::Activity;
 using wrap::org::freedesktop::monado::ipc::Client;
 using xrt::auxiliary::android::getAppInfo;
@@ -83,6 +87,11 @@ ipc_client_android_create(struct _JavaVM *vm, void *activity)
 int
 ipc_client_android_blocking_connect(struct ipc_client_android *ica)
 {
+	// Before android Q, onServiceConnected always returns on main thread, which might cause deadlock.
+	if (android_get_device_api_level() < __ANDROID_API_Q__) {
+		android_looper_poll_until_activity_resumed();
+	}
+
 	try {
 		int fd = ica->client.blockingConnect(ica->activity, XRT_ANDROID_PACKAGE);
 		return fd;

src/xrt/ipc/android/src/main/java/org/freedesktop/monado/ipc/Client.java

@@ -16,6 +16,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.ServiceConnection;
 import android.content.pm.PackageManager;
+import android.os.Build;
 import android.os.IBinder;
 import android.os.ParcelFileDescriptor;
 import android.os.RemoteException;
@@ -32,6 +33,7 @@ import org.freedesktop.monado.auxiliary.NativeCounterpart;
 import org.freedesktop.monado.auxiliary.SystemUiController;
 
 import java.io.IOException;
+import java.util.concurrent.Executors;
 
 /**
  * Provides the client-side code to initiate connection to Monado IPC service.
@@ -257,19 +259,30 @@ public class Client implements ServiceConnection {
             Log.e(TAG, "startForegroundService: Service " + intent.toString() + " does not exist!");
             return false;
         }
-        if (!context.bindService(intent,
-                this,
-                Context.BIND_AUTO_CREATE
-                        | Context.BIND_IMPORTANT
-                        | Context.BIND_INCLUDE_CAPABILITIES
-                        | Context.BIND_ABOVE_CLIENT)) {
-            Log.e(TAG, "bindService: Service " + intent.toString() + " could not be found to bind!");
+
+        if (!bindService(context, intent)) {
+            Log.e(TAG,
+                    "bindService: Service " + intent.toString() + " could not be found to bind!");
             return false;
         }
+
         // does not bind right away! This takes some time.
         return true;
     }
 
+    private boolean bindService(Context context, Intent intent) {
+        boolean result;
+        int flags = Context.BIND_AUTO_CREATE | Context.BIND_IMPORTANT | Context.BIND_ABOVE_CLIENT;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            result = context.bindService(intent, flags | Context.BIND_INCLUDE_CAPABILITIES,
+                    Executors.newSingleThreadExecutor(), this);
+        } else {
+            result = context.bindService(intent, this, flags);
+        }
+
+        return result;
+    }
+
     /**
      * Some on-failure cleanup.
      */