X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/057bbea996c9669085dbc1bd5744cb8a1f91c1a6..635188886cb9b98f353a1c3869dee898f9b73b8b:/examples/msg/chord/chord.c

diff --git a/examples/msg/chord/chord.c b/examples/msg/chord/chord.c
index c3fe12cff4..a3b7830071 100644
--- a/examples/msg/chord/chord.c
+++ b/examples/msg/chord/chord.c
@@ -633,16 +633,19 @@ static int remote_find_successor(node_t node, int ask_to, int id)
         XBT_DEBUG("Received a task (%p)", task_received);
         task_data_t ans_data = MSG_task_get_data(task_received);
 
-        if (MC_is_active()) {
-          // the model-checker is expected to find a counter-example here. 
-	  // 
-	  // As you can see in the test right below, task_received is not always equal to task_sent 
-	  // (as messages from differing round can interleave). But the previous version of this code 
-	  // wrongly assumed that, leading to problems. But this only occured on large platforms,
-	  // leading to hardly usable traces. So we used the model-checker to track down the issue, 
-	  // and we came down to this test, that explained the bug in a snap.
-          MC_assert(task_received == task_sent);
-        }
+	// Once upon a time, our code assumed that here, task_received != task_sent all the time
+	// 
+	// This assumption is wrong (as messages from differing round can interleave), leading to a bug in our code.
+	// We failed to find this bug directly, as it only occured on large platforms, leading to hardly usable traces.
+	// Instead, we used the model-checker to track down the issue by adding the following test here in the code:
+	//   if (MC_is_active()) {
+	//      MC_assert(task_received == task_sent);
+        //   }
+	// That explained the bug in a snap, with a very cool example and everything.
+	// 
+	// This MC_assert is now desactivated as the case is now properly handled in our code and we don't want the
+	//   MC to fail any further under that condition, but this comment is here to as a memorial for this first 
+	//   brillant victory of the model-checking in the SimGrid community :)
 
         if (task_received != task_sent) {
           // this is not the expected answer