merged

1 files changed, 48 insertions, 0 deletions

diff --git a/sql/sql_list.h b/sql/sql_list.h
index ac0f7f7012a..09c01931c38 100644
--- a/sql/sql_list.h
+++ b/sql/sql_list.h
@@ -192,6 +192,54 @@ public:
   friend class error_list;
   friend class error_list_iterator;
 
+#ifdef LIST_EXTRA_DEBUG
+  /*
+    Check list invariants and print results into trace. Invariants are:
+      - (*last) points to end_of_list
+      - There are no NULLs in the list.
+      - base_list::elements is the number of elements in the list.
+
+    SYNOPSIS
+      check_list()
+        name  Name to print to trace file
+
+    RETURN 
+      1  The list is Ok.
+      0  List invariants are not met.
+  */
+
+  bool check_list(const char *name)
+  {
+    base_list *list= this;
+    list_node *node= first;
+    uint cnt= 0;
+
+    while (node->next != &end_of_list)
+    {
+      if (!node->info)
+      {
+        DBUG_PRINT("list_invariants",("%s: error: NULL element in the list", 
+                                      name));
+        return FALSE;
+      }
+      node= node->next;
+      cnt++;
+    }
+    if (last != &(node->next))
+    {
+      DBUG_PRINT("list_invariants", ("%s: error: wrong last pointer", name));
+      return FALSE;
+    }
+    if (cnt+1 != elements)
+    {
+      DBUG_PRINT("list_invariants", ("%s: error: wrong element count", name));
+      return FALSE;
+    }
+    DBUG_PRINT("list_invariants", ("%s: list is ok", name));
+    return TRUE;
+  }
+#endif // LIST_EXTRA_DEBUG
+
 protected:
   void after(void *info,list_node *node)
   {