1 files changed, 24 insertions, 5 deletions
diff --git a/otherlibs/threads/mutex.ml b/otherlibs/threads/mutex.ml
index c9eb0f820..551bc5706 100644
--- a/otherlibs/threads/mutex.ml
+++ b/otherlibs/threads/mutex.ml
@@ -11,8 +11,27 @@
 
 (* $Id$ *)
 
-type t
-external new: unit -> t = "csl_mutex_new"
-external lock: t -> unit = "csl_mutex_lock"
-external try_lock: t -> bool = "csl_mutex_try_lock"
-external unlock: t -> unit = "csl_mutex_unlock"
+type t = { mutable locked: bool; mutable waiting: Thread.t list }
+
+let new () = { locked = false; waiting = [] }
+
+let rec lock m =
+  if m.locked then begin                (* test and set atomic *)
+    Thread.critical_section := true;
+    m.waiting <- Thread.self() :: m.waiting;
+    Thread.sleep();
+    lock m
+  end else begin
+    m.locked <- true                    (* test and set atomic *)
+  end
+
+let try_lock m =                        (* test and set atomic *)
+  if m.locked then false else begin m.locked <- true; true end
+
+let unlock m =
+  (* Don't play with Thread.critical_section here because of Condition.wait *)
+  let w = m.waiting in                  (* atomic *)
+  m.waiting <- [];                      (* atomic *)
+  m.locked <- false;                    (* atomic *)
+  List.iter Thread.wakeup w
+