fbshipit-source-id: d0f4b1833968aae403b114119f4e8cda184361c9

libs/fbjni/src/main/cpp/include/fb/Countable.h

@@ -0,0 +1,45 @@
+/*
+ *  Copyright (c) 2015-present, Facebook, Inc.
+ *
+ *  This source code is licensed under the MIT license found in the LICENSE
+ *  file in the root directory of this source tree.
+ *
+ */
+#pragma once
+#include <atomic>
+#include <fb/assert.h>
+#include <fb/noncopyable.h>
+#include <fb/nonmovable.h>
+#include <fb/RefPtr.h>
+
+namespace facebook {
+
+class Countable : public noncopyable, public nonmovable {
+public:
+  // RefPtr expects refcount to start at 0
+  Countable() : m_refcount(0) {}
+  virtual ~Countable()
+  {
+    FBASSERT(m_refcount == 0);
+  }
+
+private:
+  void ref() {
+    ++m_refcount;
+  }
+
+  void unref() {
+    if (0 == --m_refcount) {
+      delete this;
+    }
+  }
+
+  bool hasOnlyOneRef() const {
+    return m_refcount == 1;
+  }
+
+  template <typename T> friend class RefPtr;
+  std::atomic<int> m_refcount;
+};
+
+}