[android] MapRendererRunnable - avoid weak reference table overflow

Apparently on some devices the weak reference table is limited (numbers around 52000). Even though we don't use that many weak references, when GC is not called for a while they can stack up and a crash will occur before the GC has had the time to clear the references. The C++ peer now holds on to a global ref (strong) which can be obtained to queue the java peer and then release automatically so that the GC can take over after the runnable has been executed.

1 files changed, 3 insertions, 4 deletions

diff --git a/platform/android/src/map_renderer_runnable.hpp b/platform/android/src/map_renderer_runnable.hpp
index 75646a442d..46fb028d26 100644
--- a/platform/android/src/map_renderer_runnable.hpp
+++ b/platform/android/src/map_renderer_runnable.hpp
@@ -8,8 +8,6 @@
 
 #include <jni/jni.hpp>
 
-#include "jni/generic_global_ref_deleter.hpp"
-
 namespace mbgl {
 namespace android {
 
@@ -39,10 +37,11 @@ public:
 
     void run(jni::JNIEnv&);
 
-    jni::Object<MapRendererRunnable> getPeer();
+    // Transfers ownership of the Peer object to the caller
+    jni::UniqueObject<MapRendererRunnable> peer();
 
 private:
-    GenericUniqueWeakObject<MapRendererRunnable> javaPeer;
+    jni::UniqueObject<MapRendererRunnable> javaPeer;
     std::weak_ptr<Mailbox> mailbox;
 };