ClickHouse/dbms/src/Storages/TableStructureLockHolder.h
Alexey Zatelepin f3ea9541fc add comments
2019-03-07 21:34:46 +03:00

38 lines
754 B
C++

#pragma once
#include <Common/RWLock.h>
namespace DB
{
/// Structs that hold table structure (columns, their types, default values etc.) locks when executing queries.
/// See IStorage::lock* methods for comments.
struct TableStructureWriteLockHolder
{
void release()
{
*this = TableStructureWriteLockHolder();
}
private:
friend class IStorage;
/// Order is important.
RWLockImpl::LockHolder alter_intention_lock;
RWLockImpl::LockHolder new_data_structure_lock;
RWLockImpl::LockHolder structure_lock;
};
struct TableStructureReadLockHolder
{
private:
friend class IStorage;
/// Order is important.
RWLockImpl::LockHolder new_data_structure_lock;
RWLockImpl::LockHolder structure_lock;
};
}