Simplify Treiber stack.

src/treiber_stack.ml

@@ -1,6 +1,6 @@
 (** Treiber's Lock Free stack *)
 
-type 'a node = Nil | Next of 'a * 'a node Atomic.t
+type 'a node = Nil | Next of 'a * 'a node
 type 'a t = { head : 'a node Atomic.t }
 
 let create () =
@@ -11,8 +11,7 @@ let is_empty q = match Atomic.get q.head with Nil -> true | Next _ -> false
 
 let push q v =
   let head = Atomic.get q.head in
-  let next_node = Atomic.make head in
-  let new_node = Next (v, next_node) in
+  let new_node = Next (v, head) in
   if Atomic.compare_and_set q.head head new_node then ()
   else
     let b = Backoff.create () in
@@ -21,7 +20,7 @@ let push q v =
     (* retry *)
     let rec loop b =
       let head = Atomic.get q.head in
-      Atomic.set next_node head;
+      let new_node = Next (v, head) in
       if Atomic.compare_and_set q.head head new_node then ()
       else (
         Backoff.once b;
@@ -35,7 +34,7 @@ let pop q =
     match s with
     | Nil -> None
     | Next (v, next) ->
-        if Atomic.compare_and_set q.head s (Atomic.get next) then Some v
+        if Atomic.compare_and_set q.head s next then Some v
         else (
           Backoff.once b;
           loop b)
@@ -45,7 +44,7 @@ let pop q =
   match s with
   | Nil -> None
   | Next (v, next) ->
-      if Atomic.compare_and_set q.head s (Atomic.get next) then Some v
+      if Atomic.compare_and_set q.head s next then Some v
       else
         let b = Backoff.create () in
         Backoff.once b;