mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-18 21:51:57 +00:00
139 lines
3.7 KiB
C++
139 lines
3.7 KiB
C++
#pragma once
|
||
|
||
#include <boost/noncopyable.hpp>
|
||
|
||
#include <DB/Common/ProfileEvents.h>
|
||
#include <DB/Common/Allocator.h>
|
||
|
||
#include <DB/Common/Exception.h>
|
||
#include <DB/Core/ErrorCodes.h>
|
||
#include <DB/Core/Defines.h>
|
||
|
||
|
||
namespace DB
|
||
{
|
||
|
||
|
||
/** Замена std::vector<char> для использования в буферах.
|
||
* Отличается тем, что не делает лишний memset. (И почти ничего не делает.)
|
||
* Также можно попросить выделять выровненный кусок памяти.
|
||
*/
|
||
struct Memory : boost::noncopyable, Allocator
|
||
{
|
||
size_t m_capacity = 0;
|
||
size_t m_size = 0;
|
||
char * m_data = nullptr;
|
||
size_t alignment = 0;
|
||
|
||
Memory() {}
|
||
|
||
/// Если alignment != 0, то будет выделяться память, выровненная на alignment.
|
||
Memory(size_t size_, size_t alignment_ = 0) : m_capacity(size_), m_size(m_capacity), alignment(alignment_)
|
||
{
|
||
alloc();
|
||
}
|
||
|
||
~Memory()
|
||
{
|
||
dealloc();
|
||
}
|
||
|
||
Memory(Memory && rhs)
|
||
{
|
||
*this = std::move(rhs);
|
||
}
|
||
|
||
Memory & operator=(Memory && rhs)
|
||
{
|
||
std::swap(m_capacity, rhs.m_capacity);
|
||
std::swap(m_size, rhs.m_size);
|
||
std::swap(m_data, rhs.m_data);
|
||
std::swap(alignment, rhs.alignment);
|
||
|
||
return *this;
|
||
}
|
||
|
||
size_t size() const { return m_size; }
|
||
const char & operator[](size_t i) const { return m_data[i]; }
|
||
char & operator[](size_t i) { return m_data[i]; }
|
||
|
||
void resize(size_t new_size)
|
||
{
|
||
if (0 == m_capacity)
|
||
{
|
||
m_size = m_capacity = new_size;
|
||
alloc();
|
||
}
|
||
else if (new_size < m_capacity)
|
||
{
|
||
m_size = new_size;
|
||
return;
|
||
}
|
||
else
|
||
{
|
||
new_size = align(new_size, alignment);
|
||
/// @todo pointer to void can be converted to pointer to any type with static_cast by ISO C++, reinterpret_cast has no advantages
|
||
m_data = reinterpret_cast<char *>(Allocator::realloc(m_data, m_capacity, new_size, alignment));
|
||
m_capacity = new_size;
|
||
m_size = m_capacity;
|
||
}
|
||
}
|
||
|
||
static size_t align(const size_t value, const size_t alignment)
|
||
{
|
||
if (!alignment)
|
||
return value;
|
||
|
||
return (value + alignment - 1) / alignment * alignment;
|
||
}
|
||
|
||
private:
|
||
void alloc()
|
||
{
|
||
if (!m_capacity)
|
||
{
|
||
m_data = nullptr;
|
||
return;
|
||
}
|
||
|
||
ProfileEvents::increment(ProfileEvents::IOBufferAllocs);
|
||
ProfileEvents::increment(ProfileEvents::IOBufferAllocBytes, m_capacity);
|
||
|
||
size_t new_capacity = align(m_capacity, alignment);
|
||
/// @todo pointer to void can be converted to pointer to any type with static_cast by ISO C++, reinterpret_cast has no advantages
|
||
m_data = reinterpret_cast<char *>(Allocator::alloc(new_capacity, alignment));
|
||
m_capacity = new_capacity;
|
||
m_size = m_capacity;
|
||
}
|
||
|
||
void dealloc()
|
||
{
|
||
if (!m_data)
|
||
return;
|
||
|
||
/// @todo pointer to any type can be implicitly converted to pointer to void, no cast required
|
||
Allocator::free(reinterpret_cast<void *>(m_data), m_capacity);
|
||
m_data = nullptr; /// Чтобы избежать double free, если последующий вызов alloc кинет исключение.
|
||
}
|
||
};
|
||
|
||
|
||
/** Буфер, который может сам владеть своим куском памяти для работы.
|
||
* Аргумент шаблона - ReadBuffer или WriteBuffer
|
||
*/
|
||
template <typename Base>
|
||
class BufferWithOwnMemory : public Base
|
||
{
|
||
protected:
|
||
Memory memory;
|
||
public:
|
||
/// Если передать не-NULL existing_memory, то буфер не будет создавать свой кусок памяти, а будет использовать существующий (и не будет им владеть).
|
||
BufferWithOwnMemory(size_t size = DBMS_DEFAULT_BUFFER_SIZE, char * existing_memory = nullptr, size_t alignment = 0) : Base(nullptr, 0), memory(existing_memory ? 0 : size, alignment)
|
||
{
|
||
Base::set(existing_memory ? existing_memory : &memory[0], size);
|
||
}
|
||
};
|
||
|
||
|
||
}
|