MDEV-17933 slow server status - dict_sys_get_size()

dict_sys_get_size(): Replace the time-consuming loop with
a crude estimate that can be computed without holding any mutex.

Even before dict_sys->size was removed in MDEV-13325,
not all memory allocations by the InnoDB data dictionary cache
were being accounted for. One example is foreign key constraints.
Another example is virtual column metadata, starting with 10.2.

storage/innobase/dict/dict0dict.cc

@@ -2,7 +2,7 @@
 
 Copyright (c) 1996, 2016, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2012, Facebook Inc.
-Copyright (c) 2013, 2018, MariaDB Corporation.
+Copyright (c) 2013, 2019, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -7250,30 +7250,14 @@ UNIV_INTERN
 ulint
 dict_sys_get_size()
 {
-	ulint size = 0;
-
-	ut_ad(dict_sys);
-
-	mutex_enter(&dict_sys->mutex);
-
-	for(ulint i = 0; i < hash_get_n_cells(dict_sys->table_hash); i++) {
-		dict_table_t* table;
-
-		for (table = static_cast<dict_table_t*>(HASH_GET_FIRST(dict_sys->table_hash,i));
-		     table != NULL;
-		     table = static_cast<dict_table_t*>(HASH_GET_NEXT(name_hash, table))) {
-			dict_index_t* index;
-			size += mem_heap_get_size(table->heap) + strlen(table->name) +1;
-
-			for(index = dict_table_get_first_index(table);
-			    index != NULL;
-			    index = dict_table_get_next_index(index)) {
-				size += mem_heap_get_size(index->heap);
-			}
-		}
-	}
-
-	mutex_exit(&dict_sys->mutex);
-
-	return (size);
+	/* No mutex; this is a very crude approximation anyway */
+	ulint size = UT_LIST_GET_LEN(dict_sys->table_LRU)
+		+ UT_LIST_GET_LEN(dict_sys->table_non_LRU);
+	size *= sizeof(dict_table_t)
+		+ sizeof(dict_index_t) * 2
+		+ (sizeof(dict_col_t) + sizeof(dict_field_t)) * 10
+		+ sizeof(dict_field_t) * 5 /* total number of key fields */
+		+ 200; /* arbitrary, covering names and overhead */
+
+	return size;
 }

storage/innobase/srv/srv0srv.cc

@@ -3,7 +3,7 @@
 Copyright (c) 1995, 2017, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2008, 2009 Google Inc.
 Copyright (c) 2009, Percona Inc.
-Copyright (c) 2013, 2017, MariaDB Corporation.
+Copyright (c) 2013, 2019, MariaDB Corporation.
 
 Portions of this file contain modifications contributed and copyrighted by
 Google, Inc. Those modifications are gratefully acknowledged and are described
@@ -1341,8 +1341,6 @@ srv_printf_innodb_monitor(
 		"; in additional pool allocated " ULINTPF "\n",
 		ut_total_allocated_memory,
 		mem_pool_get_reserved(mem_comm_pool));
-	fprintf(file, "Dictionary memory allocated " ULINTPF "\n",
-		dict_sys_get_size());
 
 	buf_print_io(file);
 

storage/xtradb/dict/dict0dict.cc

@@ -2,7 +2,7 @@
 
 Copyright (c) 1996, 2017, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2012, Facebook Inc.
-Copyright (c) 2013, 2018, MariaDB Corporation.
+Copyright (c) 2013, 2019, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -7252,30 +7252,14 @@ UNIV_INTERN
 ulint
 dict_sys_get_size()
 {
-	ulint size = 0;
-
-	ut_ad(dict_sys);
-
-	mutex_enter(&dict_sys->mutex);
-
-	for(ulint i = 0; i < hash_get_n_cells(dict_sys->table_hash); i++) {
-		dict_table_t* table;
-
-		for (table = static_cast<dict_table_t*>(HASH_GET_FIRST(dict_sys->table_hash,i));
-		     table != NULL;
-		     table = static_cast<dict_table_t*>(HASH_GET_NEXT(name_hash, table))) {
-			dict_index_t* index;
-			size += mem_heap_get_size(table->heap) + strlen(table->name) +1;
-
-			for(index = dict_table_get_first_index(table);
-			    index != NULL;
-			    index = dict_table_get_next_index(index)) {
-				size += mem_heap_get_size(index->heap);
-			}
-		}
-	}
-
-	mutex_exit(&dict_sys->mutex);
-
-	return (size);
+	/* No mutex; this is a very crude approximation anyway */
+	ulint size = UT_LIST_GET_LEN(dict_sys->table_LRU)
+		+ UT_LIST_GET_LEN(dict_sys->table_non_LRU);
+	size *= sizeof(dict_table_t)
+		+ sizeof(dict_index_t) * 2
+		+ (sizeof(dict_col_t) + sizeof(dict_field_t)) * 10
+		+ sizeof(dict_field_t) * 5 /* total number of key fields */
+		+ 200; /* arbitrary, covering names and overhead */
+
+	return size;
 }

storage/xtradb/srv/srv0srv.cc

@@ -3,7 +3,7 @@
 Copyright (c) 1995, 2017, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2008, 2009 Google Inc.
 Copyright (c) 2009, Percona Inc.
-Copyright (c) 2013, 2017, MariaDB Corporation.
+Copyright (c) 2013, 2019, MariaDB Corporation.
 
 Portions of this file contain modifications contributed and copyrighted by
 Google, Inc. Those modifications are gratefully acknowledged and are described
@@ -1642,9 +1642,7 @@ srv_printf_innodb_monitor(
 					? (recv_sys->addr_hash->n_cells * sizeof(hash_cell_t)) : 0),
 			recv_sys_subtotal);
 
-
-	fprintf(file, "Dictionary memory allocated " ULINTPF "\n",
-		dict_sys ? dict_sys_get_size() : 0);
+	fprintf(file, "Dictionary memory allocated " ULINTPF "\n", dict_size);
 
 	buf_print_io(file);