# HG changeset patch
# User wenzelm
# Date 1418391117 -3600
# Node ID e557a9ddee5f4671475d6d0b69b5245f6eb71173
# Parent  853a8cb902aa7ac3648cbf82ca98e655172b45ce
Synchronized.value is actually synchronized (NB: underlying Unsynchronized.ref is not necessarily volatile);

diff -r 853a8cb902aa -r e557a9ddee5f NEWS
--- a/NEWS	Fri Dec 12 14:30:33 2014 +0100
+++ b/NEWS	Fri Dec 12 14:31:57 2014 +0100
@@ -235,6 +235,9 @@
 * Renamed "pairself" to "apply2", in accordance to @{apply 2}.
 INCOMPATIBILITY.
 
+* Synchronized.value (ML) is actually synchronized (as in Scala):
+subtle change of semantics with minimal potential for INCOMPATIBILITY.
+
 
 *** System ***
 
diff -r 853a8cb902aa -r e557a9ddee5f src/Pure/Concurrent/synchronized.ML
--- a/src/Pure/Concurrent/synchronized.ML	Fri Dec 12 14:30:33 2014 +0100
+++ b/src/Pure/Concurrent/synchronized.ML	Fri Dec 12 14:31:57 2014 +0100
@@ -33,7 +33,8 @@
   cond = ConditionVar.conditionVar (),
   var = Unsynchronized.ref x};
 
-fun value (Var {var, ...}) = ! var;
+fun value (Var {name, lock, var, ...}) =
+  Multithreading.synchronized name lock (fn () => ! var);
 
 
 (* synchronized access *)