1
0
mirror of https://github.com/MariaDB/server.git synced 2025-07-27 18:02:13 +03:00

Patch that changes metadata locking subsystem to use mutex per lock and

condition variable per context instead of one mutex and one conditional
variable for the whole subsystem.

This should increase concurrency in this subsystem.

It also opens the way for further changes which are necessary to solve
such bugs as bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock"
and bug #37346 "innodb does not detect deadlock between update and alter
table".

Two other notable changes done by this patch:

- MDL subsystem no longer implicitly acquires global intention exclusive
  metadata lock when per-object metadata lock is acquired. Now this has
  to be done by explicit calls outside of MDL subsystem.
- Instead of using separate MDL_context for opening system tables/tables
  for purposes of I_S we now create MDL savepoint in the main context
  before opening tables and rollback to this savepoint after closing
  them. This means that it is now possible to get ER_LOCK_DEADLOCK error
  even not inside a transaction. This might happen in unlikely case when
  one runs DDL on one of system tables while also running DDL on some
  other tables. Cases when this ER_LOCK_DEADLOCK error is not justified
  will be addressed by advanced deadlock detector for MDL subsystem which
  we plan to implement.
This commit is contained in:
Dmitry Lenev
2010-01-21 23:43:03 +03:00
parent c005126107
commit a63f8480db
24 changed files with 1595 additions and 848 deletions

View File

@ -18,7 +18,8 @@
#include <my_global.h>
template <typename T, typename B> class I_P_List_iterator;
template <typename T, typename B, typename C> class I_P_List_iterator;
class I_P_List_null_counter;
/**
@ -47,10 +48,14 @@ template <typename T, typename B> class I_P_List_iterator;
return &el->prev;
}
};
@param C Policy class specifying how counting of elements in the list
should be done. Instance of this class is also used as a place
where information about number of list elements is stored.
@sa I_P_List_null_counter, I_P_List_counter
*/
template <typename T, typename B>
class I_P_List
template <typename T, typename B, typename C = I_P_List_null_counter>
class I_P_List : public C
{
T *first;
@ -61,7 +66,7 @@ class I_P_List
*/
public:
I_P_List() : first(NULL) { };
inline void empty() { first= NULL; }
inline void empty() { first= NULL; C::reset(); }
inline bool is_empty() const { return (first == NULL); }
inline void push_front(T* a)
{
@ -70,6 +75,7 @@ public:
*B::prev_ptr(first)= B::next_ptr(a);
first= a;
*B::prev_ptr(a)= &first;
C::inc();
}
inline void push_back(T *a)
{
@ -107,21 +113,23 @@ public:
if (next)
*B::prev_ptr(next)= *B::prev_ptr(a);
**B::prev_ptr(a)= next;
C::dec();
}
inline T* front() { return first; }
inline const T *front() const { return first; }
void swap(I_P_List<T,B> &rhs)
void swap(I_P_List<T, B, C> &rhs)
{
swap_variables(T *, first, rhs.first);
if (first)
*B::prev_ptr(first)= &first;
if (rhs.first)
*B::prev_ptr(rhs.first)= &rhs.first;
C::swap(rhs);
}
#ifndef _lint
friend class I_P_List_iterator<T, B>;
friend class I_P_List_iterator<T, B, C>;
#endif
typedef I_P_List_iterator<T, B> Iterator;
typedef I_P_List_iterator<T, B, C> Iterator;
};
@ -129,15 +137,15 @@ public:
Iterator for I_P_List.
*/
template <typename T, typename B>
template <typename T, typename B, typename C = I_P_List_null_counter>
class I_P_List_iterator
{
const I_P_List<T, B> *list;
const I_P_List<T, B, C> *list;
T *current;
public:
I_P_List_iterator(const I_P_List<T, B> &a) : list(&a), current(a.first) {}
I_P_List_iterator(const I_P_List<T, B> &a, T* current_arg) : list(&a), current(current_arg) {}
inline void init(I_P_List<T, B> &a)
I_P_List_iterator(const I_P_List<T, B, C> &a) : list(&a), current(a.first) {}
I_P_List_iterator(const I_P_List<T, B, C> &a, T* current_arg) : list(&a), current(current_arg) {}
inline void init(const I_P_List<T, B, C> &a)
{
list= &a;
current= a.first;
@ -160,4 +168,39 @@ public:
}
};
/**
Element counting policy class for I_P_List to be used in
cases when no element counting should be done.
*/
class I_P_List_null_counter
{
protected:
void reset() {}
void inc() {}
void dec() {}
void swap(I_P_List_null_counter &rhs) {}
};
/**
Element counting policy class for I_P_List which provides
basic element counting.
*/
class I_P_List_counter
{
uint m_counter;
protected:
I_P_List_counter() : m_counter (0) {}
void reset() {m_counter= 0;}
void inc() {m_counter++;}
void dec() {m_counter--;}
void swap(I_P_List_counter &rhs)
{ swap_variables(uint, m_counter, rhs.m_counter); }
public:
uint elements() const { return m_counter; }
};
#endif