fix weak_ptr leak

src/util/WeakPtrsMap.hpp

@@ -0,0 +1,43 @@
+#include <mutex>
+#include <memory>
+#include <unordered_map>
+
+namespace util {
+    template <typename K, typename V>
+    class WeakPtrsMap {
+        std::unordered_map<K, std::weak_ptr<V>> map;
+        std::mutex mutex;
+    public:
+        std::weak_ptr<V>& operator[](const K& k) {
+            return map[k];
+        }
+
+        std::shared_ptr<V> fetch(const K& k) {
+            auto found = map.find(k);
+            if (found == map.end()) {
+                return nullptr;
+            }
+            auto ptr = found->second.lock();
+            if (ptr == nullptr) {
+                map.erase(found);
+            }
+            return ptr;
+        }
+
+        void erase(const K& k) {
+            map.erase(k);
+        }
+
+        size_t size() const {
+            return map.size();
+        }
+
+        void lock() {
+            mutex.lock();
+        }
+
+        void unlock() {
+            mutex.unlock();
+        }
+    };
+}