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Implementation of Monty's idea about clear_alloc_root() optimization and cleanup of work

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with memory roots in THD/Statement/Item_arena.
Added assertions preventing memory allocation on bzero'ed MEM_ROOT since it is worked by 
pure luck and was very ineffective.
This commit is contained in:
dlenev@brandersnatch.localdomain
2004-09-23 13:48:17 +04:00
parent c12c9af224
commit f5d1b711c6
5 changed files with 102 additions and 35 deletions
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73
sql/sql_class.cc
View File

@@ -221,7 +221,6 @@ THD::THD()
init();
/* Initialize sub structures */
clear_alloc_root(&transaction.mem_root);
init_alloc_root(&warn_root, WARN_ALLOC_BLOCK_SIZE, WARN_ALLOC_PREALLOC_SIZE);
user_connect=(USER_CONN *)0;
hash_init(&user_vars, &my_charset_bin, USER_VARS_HASH_SIZE, 0, 0,
@@ -258,6 +257,7 @@ THD::THD()
transaction.trans_log.end_of_file= max_binlog_cache_size;
}
#endif
init_alloc_root(&transaction.mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
{
ulong tmp=sql_rnd_with_mutex();
randominit(&rand, tmp + (ulong) &rand, tmp + (ulong) ::query_id);
@@ -303,12 +303,12 @@ void THD::init(void)
void THD::init_for_queries()
{
ha_enable_transaction(this,TRUE);
init_sql_alloc(&mem_root,
variables.query_alloc_block_size,
variables.query_prealloc_size);
init_sql_alloc(&transaction.mem_root,
variables.trans_alloc_block_size,
variables.trans_prealloc_size);
reset_root_defaults(&mem_root, variables.query_alloc_block_size,
variables.query_prealloc_size);
reset_root_defaults(&transaction.mem_root,
variables.trans_alloc_block_size,
variables.trans_prealloc_size);
}
@@ -1331,6 +1331,17 @@ void select_dumpvar::cleanup()
}
/*
Create arena for already constructed THD.
SYNOPSYS
Item_arena()
thd - thread for which arena is created
DESCRIPTION
Create arena for already existing THD using its variables as parameters
for memory root initialization.
*/
Item_arena::Item_arena(THD* thd)
:free_list(0),
state(INITIALIZED)
@@ -1341,24 +1352,31 @@ Item_arena::Item_arena(THD* thd)
}
/* This constructor is called when Item_arena is a subobject of THD */
/*
Create arena and optionally initialize memory root.
Item_arena::Item_arena()
SYNOPSYS
Item_arena()
init_mem_root - whenever we need to initialize memory root
DESCRIPTION
Create arena and optionally initialize memory root with minimal
possible parameters.
NOTE
We use this constructor when arena is part of THD, but reinitialize
its memory root in THD::init_for_queries() before execution of real
statements.
*/
Item_arena::Item_arena(bool init_mem_root)
:free_list(0),
state(CONVENTIONAL_EXECUTION)
{
clear_alloc_root(&mem_root);
}
Item_arena::Item_arena(bool init_mem_root)
:free_list(0),
state(INITIALIZED)
{
if (init_mem_root)
clear_alloc_root(&mem_root);
init_alloc_root(&mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
}
Item_arena::Type Item_arena::type() const
{
DBUG_ASSERT("Item_arena::type()" == "abstract");
@@ -1366,10 +1384,6 @@ Item_arena::Type Item_arena::type() const
}
Item_arena::~Item_arena()
{}
/*
Statement functions
*/
@@ -1393,7 +1407,8 @@ Statement::Statement(THD *thd)
*/
Statement::Statement()
:id(0),
:Item_arena((bool)TRUE),
id(0),
set_query_id(1),
allow_sum_func(0), /* initialized later */
lex(&main_lex),
@@ -1461,8 +1476,16 @@ void Item_arena::restore_backup_item_arena(Item_arena *set, Item_arena *backup)
{
set->set_item_arena(this);
set_item_arena(backup);
// reset backup mem_root to avoid its freeing
init_alloc_root(&backup->mem_root, 0, 0);
#ifdef NOT_NEEDED_NOW
/*
Reset backup mem_root to avoid its freeing.
Since Item_arena's mem_root is freed only when it is part of Statement
we need this only if we use some Statement's arena as backup storage.
But we do this only with THD::stmt_backup and this Statement is specially
handled in this respect. So this code is not really needed now.
*/
clear_alloc_root(&backup->mem_root);
#endif
}
void Item_arena::set_item_arena(Item_arena *set)