Small cleanup in code handling stored routines/table prelocking.

Use lazy initialization for Query_tables_list::sroutines hash.
This step should significantly decrease amount of memory consumed
by stored routines as we no longer will allocate chunk of memory
required for this HASH for each statement in routine.

include/hash.h

@@ -65,6 +65,8 @@ my_bool hash_check(HASH *hash);			/* Only in debug library */
 
 #define hash_clear(H) bzero((char*) (H),sizeof(*(H)))
 #define hash_inited(H) ((H)->array.buffer != 0)
+#define hash_init_opt(A,B,C,D,E,F,G,H) \
+          (!hash_inited(A) && _hash_init(A,B,C,D,E,F,G, H CALLER_INFO))
 
 #ifdef	__cplusplus
 }

sql/sp.cc

@@ -1369,6 +1369,10 @@ static bool add_used_routine(LEX *lex, Query_arena *arena,
                              const LEX_STRING *key,
                              TABLE_LIST *belong_to_view)
 {
+  hash_init_opt(&lex->sroutines, system_charset_info,
+                Query_tables_list::START_SROUTINES_HASH_SIZE,
+                0, 0, sp_sroutine_key, 0, 0);
+
   if (!hash_search(&lex->sroutines, (byte *)key->str, key->length))
   {
     Sroutine_hash_entry *rn=

sql/sql_lex.cc

@@ -1634,9 +1634,18 @@ void Query_tables_list::reset_query_tables_list(bool init)
   query_tables_last= &query_tables;
   query_tables_own_last= 0;
   if (init)
-    hash_init(&sroutines, system_charset_info, 0, 0, 0, sp_sroutine_key, 0, 0);
+  {
+    /*
+      We delay real initialization of hash (and therefore related
+      memory allocation) until first insertion into this hash.
+    */
+    hash_clear(&sroutines);
+  }
   else if (sroutines.records)
+  {
+    /* Non-zero sroutines.records means that hash was initialized. */
     my_hash_reset(&sroutines);
+  }
   sroutines_list.empty();
   sroutines_list_own_last= sroutines_list.next;
   sroutines_list_own_elements= 0;

sql/sql_lex.h

@@ -742,7 +742,11 @@ class Query_tables_list
     0 - indicates that this query does not need prelocking.
   */
   TABLE_LIST **query_tables_own_last;
-  /* Set of stored routines called by statement. */
+  /*
+    Set of stored routines called by statement.
+    (Note that we use lazy-initialization for this hash).
+  */
+  enum { START_SROUTINES_HASH_SIZE= 16 };
   HASH sroutines;
   /*
     List linking elements of 'sroutines' set. Allows you to add new elements