stats: track if the stats have been enabled and prevent requesting master id

Track the point in the initialization where statistics have been registered.
After this point registering new masterIds can no longer work as some
SimObjects may have sized stats vectors based on the previous value. If someone
tries to register a masterId after this point the simulator executes fatal().

1 files changed, 17 insertions, 0 deletions

diff --git a/src/base/statistics.cc b/src/base/statistics.cc
index e3f3ad78b..545d08cab 100644
--- a/src/base/statistics.cc
+++ b/src/base/statistics.cc
@@ -441,6 +441,23 @@ registerResetCallback(Callback *cb)
     resetQueue.add(cb);
 }
 
+bool _enabled = false;
+
+bool
+enabled()
+{
+    return _enabled;
+}
+
+void
+enable()
+{
+    if (_enabled)
+        fatal("Stats are already enabled");
+
+    _enabled = true;
+}
+
 } // namespace Stats
 
 void