make Looper, Handler, and MessageQueue work properly

this for example makes Unity apps not steal the main thread,
hanging Gtk.

src/api-impl-jni/android_os_MessageQueue.c

@@ -0,0 +1,62 @@
+#include "defines.h"
+#include "util.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/* TODO put these in a header */
+typedef void ALooper;
+ALooper * ALooper_prepare(void);
+void ALooper_wake(ALooper *looper);
+bool ALooper_isPolling(ALooper *looper);
+int ALooper_pollOnce(int timeoutMillis, int* outFd, int* outEvents, void** outData);
+
+struct native_message_queue {
+	ALooper *looper;
+	bool in_callback;
+};
+
+JNIEXPORT jlong JNICALL Java_android_os_MessageQueue_nativeInit(JNIEnv *env, jclass this)
+{
+	struct native_message_queue *message_queue = malloc(sizeof(struct native_message_queue));
+
+	message_queue->in_callback = false;
+	message_queue->looper = ALooper_prepare();
+
+	return _INTPTR(message_queue);
+}
+
+JNIEXPORT void JNICALL Java_android_os_MessageQueue_nativeDestroy(JNIEnv *env, jclass this, jlong ptr)
+{
+	struct native_message_queue *message_queue = _PTR(ptr);
+
+	free(message_queue);
+}
+
+JNIEXPORT void JNICALL Java_android_os_MessageQueue_nativePollOnce(JNIEnv *env, jclass this, jlong ptr, jint timeout_millis)
+{
+	struct native_message_queue *message_queue = _PTR(ptr);
+
+//	printf("Java_android_os_MessageQueue_nativePollOnce: entry (timeout: %d)\n", timeout_millis);
+	message_queue->in_callback = true;
+	ALooper_pollOnce(timeout_millis, NULL, NULL, NULL);
+	message_queue->in_callback = false;
+//	printf("Java_android_os_MessageQueue_nativePollOnce: exit\n");
+
+	/* TODO: what's with the exception stuff */
+}
+
+JNIEXPORT void JNICALL Java_android_os_MessageQueue_nativeWake(JNIEnv *env, jclass this, jlong ptr)
+{
+	struct native_message_queue *message_queue = _PTR(ptr);
+
+	ALooper_wake(message_queue->looper);
+}
+
+JNIEXPORT jboolean JNICALL Java_android_os_MessageQueue_nativeIsIdling(JNIEnv *env, jclass this, jlong ptr)
+{
+	struct native_message_queue *message_queue = _PTR(ptr);
+
+	return ALooper_isPolling(message_queue->looper);
+}

src/api-impl-jni/android_os_SystemClock.c

@@ -1,3 +1,6 @@
+#include <time.h>
+#include <math.h>
+
 #include "generated_headers/android_os_SystemClock.h"
 
 JNIEXPORT jlong JNICALL Java_android_os_SystemClock_elapsedRealtime(JNIEnv *env, jclass this)
@@ -5,3 +8,10 @@ JNIEXPORT jlong JNICALL Java_android_os_SystemClock_elapsedRealtime(JNIEnv *env,
 	printf("FIXME: Java_android_os_SystemClock_elapsedRealtime: returning 0\n");
 	return 0; // FIXME
 }
+
+JNIEXPORT jlong JNICALL Java_android_os_SystemClock_uptimeMillis(JNIEnv *env, jclass this)
+{
+    struct timespec t;
+    clock_gettime(CLOCK_REALTIME, &t);
+    return t.tv_sec * 1000 + lround(t.tv_nsec / 1e6);
+}

src/api-impl-jni/generated_headers/android_os_MessageQueue.h

@@ -10,42 +10,42 @@ extern "C" {
 /*
  * Class:     android_os_MessageQueue
  * Method:    nativeInit
- * Signature: ()I
+ * Signature: ()J
  */
-JNIEXPORT jint JNICALL Java_android_os_MessageQueue_nativeInit
+JNIEXPORT jlong JNICALL Java_android_os_MessageQueue_nativeInit
   (JNIEnv *, jclass);
 
 /*
  * Class:     android_os_MessageQueue
  * Method:    nativeDestroy
- * Signature: (I)V
+ * Signature: (J)V
  */
 JNIEXPORT void JNICALL Java_android_os_MessageQueue_nativeDestroy
-  (JNIEnv *, jclass, jint);
+  (JNIEnv *, jclass, jlong);
 
 /*
  * Class:     android_os_MessageQueue
  * Method:    nativePollOnce
- * Signature: (II)V
+ * Signature: (JI)V
  */
 JNIEXPORT void JNICALL Java_android_os_MessageQueue_nativePollOnce
-  (JNIEnv *, jclass, jint, jint);
+  (JNIEnv *, jclass, jlong, jint);
 
 /*
  * Class:     android_os_MessageQueue
  * Method:    nativeWake
- * Signature: (I)V
+ * Signature: (J)V
  */
 JNIEXPORT void JNICALL Java_android_os_MessageQueue_nativeWake
-  (JNIEnv *, jclass, jint);
+  (JNIEnv *, jclass, jlong);
 
 /*
  * Class:     android_os_MessageQueue
  * Method:    nativeIsIdling
- * Signature: (I)Z
+ * Signature: (J)Z
  */
 JNIEXPORT jboolean JNICALL Java_android_os_MessageQueue_nativeIsIdling
-  (JNIEnv *, jclass, jint);
+  (JNIEnv *, jclass, jlong);
 
 #ifdef __cplusplus
 }

src/api-impl-jni/generated_headers/android_os_SystemClock.h

@@ -15,6 +15,14 @@ extern "C" {
 JNIEXPORT jboolean JNICALL Java_android_os_SystemClock_setCurrentTimeMillis
   (JNIEnv *, jclass, jlong);
 
+/*
+ * Class:     android_os_SystemClock
+ * Method:    uptimeMillis
+ * Signature: ()J
+ */
+JNIEXPORT jlong JNICALL Java_android_os_SystemClock_uptimeMillis
+  (JNIEnv *, jclass);
+
 /*
  * Class:     android_os_SystemClock
  * Method:    elapsedRealtime