job/dispatch: retain the supplied function if forwarded to us

job/dispatch.hpp

@@ -30,7 +30,9 @@ namespace util::job {
     //
     // threads will have work sizes dictated by a supplied extent.
     //
-    // returns a cookie, or container of cookies, to wait on.
+    // returns a cookie that will block at destruction until all jobs have
+    // completed. it will take ownership of an forwarding-reference function
+    // if one is supplied.
     //
     // TODO: extend to 1d and 3d
     template <
@@ -39,12 +41,12 @@ namespace util::job {
         typename ...Args,
         size_t DimensionV
     >
-    std::vector<queue::cookie>
+    auto
     dispatch (
         util::job::queue &q,
         ContainerT &data,
         util::extent<DimensionV,int> chunk,
-        FunctionT &func,
+        FunctionT &&func,
         Args ...args)
     {
         auto chunked_func = [&func] (ContainerT &inner_data,
@@ -74,7 +76,7 @@ namespace util::job {
             );
         }
 
-        return cookies;
+        return std::tuple (std::forward<FunctionT> (func), std::move (cookies));
     }
 }