src/Pure/PIDE/exec.ML

--- a/src/Pure/PIDE/exec.ML	Thu Jul 11 22:53:56 2013 +0200
+++ b/src/Pure/PIDE/exec.ML	Thu Jul 11 23:24:40 2013 +0200
@@ -6,49 +6,95 @@
 
 signature EXEC =
 sig
-  val running: Document_ID.exec -> unit
+  type context
+  val no_context: context
+  val drop_context: context -> unit
+  val fresh_context: unit -> context
+  val is_running: context -> bool
+  val running: context -> Document_ID.exec -> bool
   val finished: Document_ID.exec -> bool -> unit
   val is_stable: Document_ID.exec -> bool
   val peek_running: Document_ID.exec -> Future.group option
-  val purge_unstable: unit -> unit
+  val purge_canceled: unit -> unit
+  val terminate_all: unit -> unit
 end;
 
 structure Exec: EXEC =
 struct
 
-type status = Future.group option;  (*SOME group: running, NONE: canceled/unstable*)
-val execs = Synchronized.var "Exec.execs" (Inttab.empty: status Inttab.table);
+(* global state *)
+
+datatype context = Context of Document_ID.generic;
+val no_context = Context Document_ID.none;
+
+type status = Future.group option;  (*SOME group: running, NONE: canceled*)
+val state = Synchronized.var "Exec.state" (no_context, Inttab.empty: status Inttab.table);
 
-fun running exec_id =
+
+(* unique execution context *)
+
+fun drop_context context =
+  Synchronized.change state
+    (apfst (fn context' => if context = context' then no_context else context'));
+
+fun fresh_context () =
   let
-    val group =
-      (case Future.worker_group () of
-        SOME group => group
-      | NONE => error ("Missing worker thread context for execution " ^ Document_ID.print exec_id));
-  in Synchronized.change execs (Inttab.update_new (exec_id, SOME group)) end;
+    val context = Context (Document_ID.make ());
+    val _ = Synchronized.change state (apfst (K context));
+  in context end;
+
+fun is_running context = context = fst (Synchronized.value state);
+
+
+(* registered execs *)
+
+fun running context exec_id =
+  Synchronized.guarded_access state
+    (fn (current_context, execs) =>
+      let
+        val cont = context = current_context;
+        val execs' =
+          if cont then
+            Inttab.update_new (exec_id, SOME (Future.the_worker_group ())) execs
+              handle Inttab.DUP dup => error ("Duplicate execution " ^ Document_ID.print dup)
+          else execs;
+      in SOME (cont, (current_context, execs')) end);
 
 fun finished exec_id stable =
-  Synchronized.change execs
-    (if stable then Inttab.delete exec_id else Inttab.update (exec_id, NONE));
+  Synchronized.change state
+    (apsnd (fn execs =>
+      if not (Inttab.defined execs exec_id) then
+        error ("Attempt to finish unknown execution: " ^ Document_ID.print exec_id)
+      else if stable then Inttab.delete exec_id execs
+      else Inttab.update (exec_id, NONE) execs));
 
 fun is_stable exec_id =
   not (Par_Exn.is_interrupted (Future.join_results (Goal.peek_futures exec_id))) andalso
-  (case Inttab.lookup (Synchronized.value execs) exec_id of
+  (case Inttab.lookup (snd (Synchronized.value state)) exec_id of
     NONE => true
   | SOME status => is_some status);
 
 fun peek_running exec_id =
-  (case Inttab.lookup (Synchronized.value execs) exec_id of
+  (case Inttab.lookup (snd (Synchronized.value state)) exec_id of
     SOME (SOME group) => SOME group
   | _ => NONE);
 
-fun purge_unstable () =
-  Synchronized.guarded_access execs
-    (fn tab =>
+fun purge_canceled () =
+  Synchronized.guarded_access state
+    (fn (context, execs) =>
       let
-        val unstable = Inttab.fold (fn (exec_id, NONE) => cons exec_id | _ => I) tab [];
-        val tab' = fold Inttab.delete unstable tab;
-      in SOME ((), tab') end);
+        val canceled = Inttab.fold (fn (exec_id, NONE) => cons exec_id | _ => I) execs [];
+        val execs' = fold Inttab.delete canceled execs;
+      in SOME ((), (context, execs')) end);
+
+fun terminate_all () =
+  let
+    val groups =
+      Inttab.fold (fn (_, SOME group) => cons group | _ => I)
+        (snd (Synchronized.value state)) [];
+    val _ = List.app Future.cancel_group groups;
+    val _ = List.app Future.terminate groups;
+  in () end;
 
 end;