Fix lmm_shrink() to correctly free var->cnsts[i]

diff --git a/src/surf/maxmin.c b/src/surf/maxmin.c
index 2b65794..a8c1e0a 100644 (file)
--- a/src/surf/maxmin.c
+++ b/src/surf/maxmin.c
@@ -258,6 +258,33 @@ XBT_INLINE double lmm_variable_getbound(lmm_variable_t var)
   return (var->bound);
 }
 
+/* Replace the content of elem_a with elem_b. The content of elem_b is cleared. */
+static void renew_elem_entry(lmm_element_t elem_a, lmm_element_t elem_b)
+{
+    elem_a->constraint = elem_b->constraint;
+    elem_a->variable   = elem_b->variable;
+    elem_a->value      = elem_b->value;
+
+    /* If elem_b is in the element_set swag, register the new element to the swag. */
+    if (xbt_swag_remove(elem_b, &(elem_b->constraint->element_set))) {
+      if (elem_a->variable->weight)
+        xbt_swag_insert_at_head(elem_a, &(elem_a->constraint->element_set));
+      else
+        xbt_swag_insert_at_tail(elem_a, &(elem_a->constraint->element_set));
+    }
+
+    if (xbt_swag_remove(elem_b, &(elem_b->constraint->active_element_set))) {
+      if (elem_a->variable->weight)
+        xbt_swag_insert_at_head(elem_a, &(elem_a->constraint->active_element_set));
+      else
+        xbt_swag_insert_at_tail(elem_a, &(elem_a->constraint->active_element_set));
+    }
+
+    elem_b->constraint = NULL;
+    elem_b->variable   = NULL;
+    elem_b->value      = 0;
+}
+
 void lmm_shrink(lmm_system_t sys, lmm_constraint_t cnst,
                 lmm_variable_t var)
 {
@@ -274,7 +301,7 @@ void lmm_shrink(lmm_system_t sys, lmm_constraint_t cnst,
   }
 
   if (!found) {
-    XBT_WARN("cnst %p is not found in var %p", cnst, var);
+    // XBT_WARN("cnst %p is not found in var %p", cnst, var);
     return;
   }
 
@@ -283,34 +310,38 @@ void lmm_shrink(lmm_system_t sys, lmm_constraint_t cnst,
   XBT_INFO("remove elem(value %lf, cnst %p, var %p) in var %p",
       elem->value, elem->constraint, elem->variable, var);
 
+
+
+  /* We are going to change the constraint object and the variable object.
+   * Propagate this change to other objects. Calling here (not after
+   * modification) is correct? */
+  lmm_update_modified_set(sys, cnst);
+  lmm_update_modified_set(sys, var->cnsts[0].constraint); // will look up element_set of this constraint, and then each var in the element_set, and each var->cnsts[i].
+
+
+
+  /* now var->cnsts[i] is not necessary any more */
+
   xbt_swag_remove(elem, &(elem->constraint->element_set));
-  var->cnsts[i] = var->cnsts[var->cnsts_number - 1];
+  xbt_swag_remove(elem, &(elem->constraint->active_element_set));
+  elem->constraint = NULL;
+  elem->variable = NULL;
+  elem->value = 0;
+
+
+
+  /* We do not want to have an empty element entry before the last entry. So,
+   * plug up the hole with the last one. */
+  if (i < var->cnsts_number - 1)
+    renew_elem_entry(&var->cnsts[i], &var->cnsts[var->cnsts_number - 1]);
+
   var->cnsts_number -= 1;
 
 
   if (xbt_swag_size(&(cnst->element_set)) == 0)
     make_constraint_inactive(sys, cnst);
-  else {
-    /* This shrink operation effects the given constraint as well as all the constraints of the variable? */
-    lmm_update_modified_set(sys, cnst);
-    lmm_update_modified_set(sys, var->cnsts[0].constraint);
-  }
-
-
-#if 0
-  if (!sys->selective_update_active) {
-    make_constraint_active(sys, cnst);
 
-  } else if (elem->value > 0 || var->weight > 0) {
-    make_constraint_active(sys, cnst);
-    lmm_update_modified_set(sys, cnst);
 
-    /* FIXME: Why is only the cnsts[0] used here? Don't we do this other cnts[i]? */
-    /* if a variable object has changes, we might want to propagate changes to all constraints of it? */
-    if (var->cnsts_number > 1)
-      lmm_update_modified_set(sys, var->cnsts[0].constraint);
-  }
-#endif
 
 }