diff --git a/infer/src/checkers/active.ml b/infer/src/checkers/active.ml
new file mode 100644
index 000000000..3b944d4f2
--- /dev/null
+++ b/infer/src/checkers/active.ml
@@ -0,0 +1,104 @@
+(*
+ * Copyright (c) 2016 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+(** I want to use various powersets instead of just variables like Var.Set
+    For example to track the analogues of attributes
+    I will do this running forwards later, but backwards for now.
+*)
+
+open! Utils
+
+module F = Format
+module L = Logging
+
+module PPstring = PrettyPrintable.MakePPSet(struct
+    type nonrec t = string
+    let compare = string_compare
+    let pp_element fmt s = F.fprintf fmt "%s" s
+  end)
+
+module PPrawpath = PrettyPrintable.MakePPSet(struct
+    type nonrec t = AccessPath.raw
+    let compare = AccessPath.raw_compare
+    let pp_element = AccessPath.pp_raw
+  end)
+
+module LocksDomain =  AbstractDomain.FiniteSet(PPstring)
+
+module PathDomain =  AbstractDomain.FiniteSet(PPrawpath)
+
+module ReadWriteDomain = AbstractDomain.Pair (PathDomain) (PathDomain)
+
+module CombinedDomain = AbstractDomain.Pair (LocksDomain) (ReadWriteDomain)
+(* a typical element is (){locked}, {vars and fields})  *)
+
+module TransferFunctions (CFG : ProcCfg.S) = struct
+  module CFG = CFG
+  module Domain = CombinedDomain
+  type extras = ProcData.no_extras
+
+  let is_lock_procedure pn = Procname.equal pn ModelBuiltins.__set_locked_attribute
+
+  let is_unlock_procedure pn = Procname.equal pn ModelBuiltins.__delete_locked_attribute
+
+  let add_path_to_state exp typ pathdomainstate =
+    match AccessPath.of_exp exp typ ~f_resolve_id:(fun _ -> None) with
+    | Some rawpath -> PathDomain.add rawpath pathdomainstate
+    | None -> pathdomainstate
+
+
+  let exec_instr ((lockstate,(readstate,writestate)) as astate) _ _ = function
+    | Sil.Call (_, Exp.Const (Const.Cfun pn), _, _, _) ->
+        if is_lock_procedure pn
+        then
+          ((LocksDomain.add "locked" lockstate), (readstate,writestate))
+        else if is_unlock_procedure pn
+        then
+          ((LocksDomain.remove "locked" lockstate) , (readstate,writestate))
+        else
+          astate
+
+    | Sil.Store ((Exp.Lfield ( _, _, typ) as lhsfield) , _, _, _) ->
+        if LocksDomain.is_empty lockstate then (* abstracts no lock being held*)
+          (lockstate, (readstate, add_path_to_state lhsfield typ writestate))
+        else astate
+
+    (* Note: it appears that the third arg of Store is never an Lfield in the targets of,
+       our translations, which is why we have not covered that case. *)
+    | Sil.Store (_, _, Exp.Lfield _, _) ->
+        failwith "Unexpected store instruction with rhs field"
+
+    | Sil.Load (_, (Exp.Lfield ( _, _, typ) as rhsfield) , _, _) ->
+        if LocksDomain.is_empty lockstate then (* abstracts no lock being held*)
+          (lockstate, (add_path_to_state rhsfield typ readstate, writestate))
+        else astate
+
+    |  _  ->
+        astate
+end
+
+module Analyzer =
+  AbstractInterpreter.Make
+    (ProcCfg.Normal)
+    (Scheduler.ReversePostorder)
+    (TransferFunctions)
+
+let checker { Callbacks.proc_desc; tenv; } =
+  match Analyzer.compute_post (ProcData.make_default proc_desc tenv) with
+  | Some post ->  (* I am printing to commandline and out to cater to javac and buck*)
+      ((L.stdout  "\n Procedure: %s@ "
+          (Procname.to_string (Cfg.Procdesc.get_proc_name proc_desc) )
+       );
+       L.stdout "\n POST: %a\n" CombinedDomain.pp post;
+       (L.out  "\n Procedure: %s@ "
+          (Procname.to_string (Cfg.Procdesc.get_proc_name proc_desc) )
+       );
+       L.out "\n POST: %a\n" CombinedDomain.pp post
+      )
+  | None -> ()
diff --git a/infer/src/checkers/registerCheckers.ml b/infer/src/checkers/registerCheckers.ml
index 1424fbeee..8984bd201 100644
--- a/infer/src/checkers/registerCheckers.ml
+++ b/infer/src/checkers/registerCheckers.ml
@@ -39,6 +39,7 @@ let active_procedure_checkers () =
         RepeatedCallsChecker.callback_check_repeated_calls, checkers_enabled;
         PrintfArgs.callback_printf_args, checkers_enabled;
         AnnotationReachability.Interprocedural.check_and_report, checkers_enabled;
+        Active.checker, false;
       ] in
     IList.map (fun (x, y) -> (x, y, Some Config.Java)) l in
   let c_cpp_checkers =