Merge branch '10.2-MDEV-10814-dont-dump-query-cache' of...

Merge branch '10.2-MDEV-10814-dont-dump-query-cache' of https://github.com/grooverdan/mariadb-server into grooverdan-10.2-MDEV-10814-dont-dump-query-cache

sql/sql_cache.cc

@@ -329,6 +329,9 @@ TODO list:
 */
 
 #include "mariadb.h"                          /* NO_EMBEDDED_ACCESS_CHECKS */
+#if defined(DBUG_OFF) && defined(HAVE_MADVISE)
+#include <sys/mman.h>
+#endif
 #include "sql_priv.h"
 #include "sql_basic_types.h"
 #include "sql_cache.h"
@@ -2591,7 +2594,7 @@ size_t Query_cache::init_cache()
 {
   size_t mem_bin_count, num, step;
   size_t mem_bin_size, prev_size, inc;
-  size_t additional_data_size, max_mem_bin_size, approx_additional_data_size;
+  size_t max_mem_bin_size, approx_additional_data_size;
   int align;
 
   DBUG_ENTER("Query_cache::init_cache");
@@ -2656,6 +2659,13 @@ size_t Query_cache::init_cache()
   if (!(cache= (uchar *)
         my_malloc_lock(query_cache_size+additional_data_size, MYF(0))))
     goto err;
+#if defined(DBUG_OFF) && defined(HAVE_MADVISE) &&  defined(MADV_DONTDUMP)
+  if (madvise(cache, query_cache_size+additional_data_size, MADV_DONTDUMP))
+  {
+    DBUG_PRINT("warning", ("coudn't mark query cache memory as MADV_DONTDUMP: %s",
+			 strerror(errno)));
+  }
+#endif
 
   DBUG_PRINT("qcache", ("cache length %zu, min unit %zu, %zu bins",
 		      query_cache_size, min_allocation_unit, mem_bin_num));
@@ -2818,6 +2828,13 @@ void Query_cache::free_cache()
     } while (block != queries_blocks);
   }
 
+#if defined(DBUG_OFF) && defined(HAVE_MADVISE) &&  defined(MADV_DODUMP)
+  if (madvise(cache, query_cache_size+additional_data_size, MADV_DODUMP))
+  {
+    DBUG_PRINT("warning", ("coudn't mark query cache memory as MADV_DODUMP: %s",
+			 strerror(errno)));
+  }
+#endif
   my_free(cache);
   make_disabled();
   my_hash_free(&queries);

sql/sql_cache.h

@@ -337,6 +337,7 @@ class Query_cache
     till the end of a flush operation.
   */
   mysql_mutex_t structure_guard_mutex;
+  size_t additional_data_size;
   uchar *cache;					// cache memory
   Query_cache_block *first_block;		// physical location block list
   Query_cache_block *queries_blocks;		// query list (LIFO)