Integrate newest version which avoids the need for a seperate fun.

src/async_nif.hrl

@@ -21,9 +21,10 @@
 %%
 %% -------------------------------------------------------------------
 
--spec async_nif_enqueue(reference(), function(), [term()]) -> term() | {error, term()}.
-async_nif_enqueue(R, F, A) ->
-    case erlang:apply(F, [R|A]) of
+-define(ASYNC_NIF_CALL(Fun, Args),
+	F = fun(F, T) ->
+		    R = erlang:make_ref(),
+		    case erlang:apply(F, [R|Args]) of
 			{ok, enqueued} ->
 			    receive
 				{R, {error, shutdown}=Error} ->
@@ -36,12 +37,11 @@ async_nif_enqueue(R, F, A) ->
 				    Reply
 			    end;
 			{error, eagain} ->
-            %% Work unit was not queued, try again.
-            async_nif_enqueue(R, F, A);
-        %{error, enomem} ->
-        %{error, shutdown} ->
+			    SleepyTime = min(30, (T+1)*2),
+			    timer:sleep(SleepyTime),
+			    F(F, SleepyTime);
 			Other ->
 			    Other
-    end.
-
--define(ASYNC_NIF_CALL(Fun, Args), async_nif_enqueue(erlang:make_ref(), Fun, Args)).
+		    end
+	    end,
+	F(Fun, 0)).