1 files changed, 42 insertions, 0 deletions
diff --git a/xpcom/base/JSObjectHolder.h b/xpcom/base/JSObjectHolder.h
new file mode 100644
index 0000000000..d64d41e479
--- /dev/null
+++ b/xpcom/base/JSObjectHolder.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_JSObjectHolder_h
+#define mozilla_JSObjectHolder_h
+
+#include "js/RootingAPI.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+
+// This class is useful when something on one thread needs to keep alive
+// a JS Object from another thread. If they are both on the same thread, the
+// owning class should instead be made a cycle collected SCRIPT_HOLDER class.
+// This object should only be AddRefed and Released on the same thread as
+// mJSObject.
+//
+// Note that this keeps alive the JS object until it goes away, so be sure not
+// to create cycles that keep alive the holder.
+//
+// JSObjectHolder is ISupports to make it usable with
+// NS_ReleaseOnMainThread.
+class JSObjectHolder final : public nsISupports {
+ public:
+  JSObjectHolder(JSContext* aCx, JSObject* aObject) : mJSObject(aCx, aObject) {}
+
+  NS_DECL_ISUPPORTS
+
+  JSObject* GetJSObject() { return mJSObject; }
+
+ private:
+  ~JSObjectHolder() = default;
+
+  JS::PersistentRooted<JSObject*> mJSObject;
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_JSObjectHolder_h