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MDEV-7728 - Improve xid cache scalability by using lock-free hash

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This is an addition to original patch. Some platforms are strict about atomic
op argument signedness.
This commit is contained in:
Sergey Vojtovich 2015-03-16 22:54:43 +04:00
parent e6f67c64cd
commit fec94a6b44
1 changed files with 6 additions and 5 deletions
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11
sql/sql_class.cc
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@ -5182,8 +5182,9 @@ void mark_transaction_to_rollback(THD *thd, bool all)
class XID_cache_element
{
/*
bits 1..31 are reference counter
bit 32 is UNINITIALIZED flag
bits 1..30 are reference counter
bit 31 is UNINITIALIZED flag
bit 32 is unused
Newly allocated and deleted elements have UNINITIALIZED flag set.
@ -5204,8 +5205,8 @@ class XID_cache_element
Currently m_state is only used to prevent elements from being deleted while
XA RECOVER iterates xid cache.
*/
uint32 m_state;
static const uint32 UNINITIALIZED= 1 << 31;
int32 m_state;
static const int32 UNINITIALIZED= 1 << 30;
public:
XID_STATE *m_xid_state;
bool lock()
@ -5224,7 +5225,7 @@ public:
}
void mark_uninitialized()
{
uint old= 0;
int32 old= 0;
while (!my_atomic_cas32_weak_explicit(&m_state, &old, UNINITIALIZED,
MY_MEMORY_ORDER_RELAXED,
MY_MEMORY_ORDER_RELAXED))