ANDROID: On pause, put all threads in a coma

Since not every engine respects pauseEngine(), or they're in a state
where it simply gets ignored, put all threads in a group coma. Without
this, code still kept looping and wasting cpu cycles, while the user
might want to do use her/his droid for something else.

3 files changed, 53 insertions, 5 deletions

diff --git a/backends/platform/android/android.cpp b/backends/platform/android/android.cpp
index 484f6886ec..d4a2253c30 100644
--- a/backends/platform/android/android.cpp
+++ b/backends/platform/android/android.cpp
@@ -151,6 +151,12 @@ void *OSystem_Android::timerThreadFunc(void *arg) {
 	tv.tv_nsec = 100 * 1000 * 1000;	// 100ms
 
 	while (!system->_timer_thread_exit) {
+		if (JNI::pause) {
+			LOGD("timer thread going to sleep");
+			sem_wait(&JNI::pause_sem);
+			LOGD("timer thread woke up");
+		}
+			
 		timer->handler();
 		nanosleep(&tv, 0);
 	}
@@ -192,6 +198,12 @@ void *OSystem_Android::audioThreadFunc(void *arg) {
 	uint silence_count = 33;
 
 	while (!system->_audio_thread_exit) {
+		if (JNI::pause) {
+			LOGD("audio thread going to sleep");
+			sem_wait(&JNI::pause_sem);
+			LOGD("audio thread woke up");
+		}
+			
 		buf = (byte *)env->GetPrimitiveArrayCritical(bufa, 0);
 		assert(buf);
 
@@ -401,6 +413,19 @@ bool OSystem_Android::pollEvent(Common::Event &event) {
 			_screen_changeid = JNI::surface_changeid;
 			JNI::deinitSurface();
 		}
+
+		if (JNI::pause) {
+			// release some resources
+			// TODO
+			// free textures? they're garbled anyway since no engine
+			// respects EVENT_SCREEN_CHANGED
+			LOGD("deinitialiting surface");
+			JNI::deinitSurface();
+
+			LOGD("main thread going to sleep");
+			sem_wait(&JNI::pause_sem);
+			LOGD("main thread woke up");
+		}
 	}
 
 	lockMutex(_event_queue_lock);
diff --git a/backends/platform/android/jni.cpp b/backends/platform/android/jni.cpp
index 1e28b065b4..9ecd9577e7 100644
--- a/backends/platform/android/jni.cpp
+++ b/backends/platform/android/jni.cpp
@@ -48,6 +48,9 @@ jobject JNI::_jobj_egl_surface = 0;
 Common::Archive *JNI::_asset_archive = 0;
 OSystem_Android *JNI::_system = 0;
 
+bool JNI::pause = false;
+sem_t JNI::pause_sem = { 0 };
+
 int JNI::surface_changeid = 0;
 int JNI::egl_surface_width = 0;
 int JNI::egl_surface_height = 0;
@@ -417,6 +420,10 @@ void JNI::create(JNIEnv *env, jobject self, jobject asset_manager,
 				jobject at, jint audio_sample_rate, jint audio_buffer_size) {
 	assert(!_system);
 
+	pause = false;
+	// initial value of zero!
+	sem_init(&pause_sem, 0, 0);
+
 	_asset_archive = new AndroidAssetArchive(asset_manager);
 	assert(_asset_archive);
 
@@ -477,6 +484,8 @@ void JNI::destroy(JNIEnv *env, jobject self) {
 	g_system = 0;
 	_system = 0;
 
+	sem_destroy(&pause_sem);
+
 	// see above
 	//JNI::getEnv()->DeleteWeakGlobalRef(_jobj);
 
@@ -616,13 +625,23 @@ void JNI::enableZoning(JNIEnv *env, jobject self, jboolean enable) {
 	_system->enableZoning(enable);
 }
 
-void JNI::pauseEngine(JNIEnv *env, jobject self, jboolean pause) {
-	if (!_system || !g_engine)
+void JNI::pauseEngine(JNIEnv *env, jobject self, jboolean value) {
+	if (!_system)
 		return;
 
-	if ((pause && !g_engine->isPaused()) || (!pause && g_engine->isPaused())) {
-		LOGD("pauseEngine: %d", pause);
-		g_engine->pauseEngine(pause);
+	if (g_engine)
+		if ((value && !g_engine->isPaused()) ||
+				(!value && g_engine->isPaused())) {
+			LOGD("pauseEngine: %d", value);
+			g_engine->pauseEngine(value);
+		}
+
+	pause = value;
+
+	if (!pause) {
+		// wake up all threads
+		for (uint i = 0; i < 3; ++i)
+			sem_post(&pause_sem);
 	}
 }
 
diff --git a/backends/platform/android/jni.h b/backends/platform/android/jni.h
index 7eb10791aa..569a3dd79b 100644
--- a/backends/platform/android/jni.h
+++ b/backends/platform/android/jni.h
@@ -29,6 +29,7 @@
 #if defined(__ANDROID__)
 
 #include <jni.h>
+#include <semaphore.h>
 
 #include "common/fs.h"
 #include "common/archive.h"
@@ -41,6 +42,9 @@ private:
 	virtual ~JNI();
 
 public:
+	static bool pause;
+	static sem_t pause_sem;
+
 	static int surface_changeid;
 	static int egl_surface_width;
 	static int egl_surface_height;