fix: prevent crash when jweak points to null

test-app/runtime/src/main/cpp/JEnv.h

@@ -20,6 +20,10 @@ class JEnv {
 
         jsize GetArrayLength(jarray array);
 
+        inline bool isSameObject(jobject obj1, jobject obj2) {
+            return m_env->IsSameObject(obj1, obj2) == JNI_TRUE;
+        }
+
         jmethodID GetMethodID(jclass clazz, const std::string& name, const std::string& sig);
         jmethodID GetStaticMethodID(jclass clazz, const std::string& name, const std::string& sig);
         std::pair<jmethodID,jclass> GetInterfaceStaticMethodIDAndJClass(

test-app/runtime/src/main/cpp/LRUCache.h

@@ -19,7 +19,7 @@
 
 #include <cassert>
 #include <list>
-#include <unordered_map>
+#include "robin_hood.h"
 
 namespace tns {
 // Class providing fixed-size (by number of records)
@@ -41,12 +41,12 @@ class LRUCache {
         typedef std::list<key_type> key_tracker_type;
 
         // Key to value and key history iterator
-        typedef std::unordered_map< key_type, std::pair<value_type, typename key_tracker_type::iterator> > key_to_value_type;
+        typedef robin_hood::unordered_map< key_type, std::pair<value_type, typename key_tracker_type::iterator> > key_to_value_type;
 
         // Constuctor specifies the cached function and
         // the maximum number of records to be stored
-        LRUCache(value_type (*loadCallback)(const key_type&, void*), void (*evictCallback)(const value_type&, void*), size_t capacity, void* state)
-            : m_loadCallback(loadCallback), m_capacity(capacity), m_evictCallback(evictCallback), m_state(state) {
+        LRUCache(value_type (*loadCallback)(const key_type&, void*), void (*evictCallback)(const value_type&, void*), bool (*cacheValidCallback)(const key_type&, const value_type&, void*), size_t capacity, void* state)
+            : m_loadCallback(loadCallback), m_capacity(capacity), m_evictCallback(evictCallback), m_cacheValidCallback(cacheValidCallback), m_state(state) {
             assert(m_loadCallback != nullptr);
             assert((0 < m_capacity) && (m_capacity < 10000));
         }
@@ -57,6 +57,15 @@ class LRUCache {
             // Attempt to find existing record
             auto it = m_key_to_value.find(k);
 
+            if (m_cacheValidCallback != nullptr && it != m_key_to_value.end()) {
+                //check if cache is still valid
+                if (!m_cacheValidCallback(k, (*it).second.first, m_state)) {
+                    //cache is not valid anymore, evict the key
+                    evictKey(k);
+                    it = m_key_to_value.end();
+                }
+            }
+
             if (it == m_key_to_value.end()) {
 
                 // We don't have it:
@@ -98,6 +107,17 @@ class LRUCache {
 
     private:
 
+        void evictKey(const key_type& key) {
+            auto it = m_key_to_value.find(key);
+            if (it != m_key_to_value.end()) {
+                if (m_evictCallback != nullptr) {
+                    m_evictCallback((*it).second.first, m_state);
+                }
+                m_key_tracker.erase((*it).second.second);
+                m_key_to_value.erase(it);
+            }
+        }
+
         // Record a fresh key-value pair in the cache
         void insert(const key_type& k, const value_type& v) {
             // Method is only called on cache misses
@@ -113,7 +133,7 @@ class LRUCache {
 
             // Create the key-value entry,
             // linked to the usage record.
-            m_key_to_value.insert(std::make_pair(k, std::make_pair(v, it)));
+            m_key_to_value.emplace(k, std::make_pair(v, it));
             // No need to check return,
             // given previous assert.
         }
@@ -141,6 +161,8 @@ class LRUCache {
 
         void (*m_evictCallback)(const value_type&, void*);
 
+        bool (*m_cacheValidCallback)(const key_type&, const value_type&, void*);
+
         // Maximum number of key-value pairs to be retained
         const size_t m_capacity;
 

test-app/runtime/src/main/cpp/ObjectManager.cpp

@@ -20,7 +20,7 @@ ObjectManager::ObjectManager(jobject javaRuntimeObject) :
         m_javaRuntimeObject(javaRuntimeObject),
         m_numberOfGC(0),
         m_currentObjectId(0),
-        m_cache(NewWeakGlobalRefCallback, DeleteWeakGlobalRefCallback, 1000, this) {
+        m_cache(NewWeakGlobalRefCallback, DeleteWeakGlobalRefCallback, ValidateWeakGlobalRefCallback, 1000, this) {
 
     JEnv env;
     auto runtimeClass = env.FindClass("com/tns/Runtime");
@@ -507,12 +507,15 @@ jweak ObjectManager::NewWeakGlobalRefCallback(const int &javaObjectID, void *sta
 }
 
 void ObjectManager::DeleteWeakGlobalRefCallback(const jweak &object, void *state) {
-    auto objManager = reinterpret_cast<ObjectManager *>(state);
-
     JEnv env;
     env.DeleteWeakGlobalRef(object);
 }
 
+bool ObjectManager::ValidateWeakGlobalRefCallback(const int &javaObjectID, const jweak &object, void *state) {
+    JEnv env;
+    return !env.isSameObject(object, NULL);
+}
+
 Local<Object> ObjectManager::GetEmptyObject(Isolate *isolate) {
     auto emptyObjCtorFunc = Local<Function>::New(isolate, *m_poJsWrapperFunc);
     auto context = Runtime::GetRuntime(isolate)->GetContext();

test-app/runtime/src/main/cpp/ObjectManager.h

@@ -179,6 +179,8 @@ class ObjectManager {
 
         static void DeleteWeakGlobalRefCallback(const jweak& object, void* state);
 
+        static bool ValidateWeakGlobalRefCallback(const int &javaObjectID, const jweak &object, void *state);
+
         static void JSWrapperConstructorCallback(const v8::FunctionCallbackInfo<v8::Value>& info);
 
         jobject m_javaRuntimeObject;