ClickHouse/dbms/include/DB/Common/Allocator.h

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#pragma once
#include <malloc.h>
#include <string.h>
#include <sys/mman.h>
#include <DB/Common/MemoryTracker.h>
2015-10-05 01:35:28 +00:00
#include <DB/Common/Exception.h>
#include <DB/Core/ErrorCodes.h>
/** Отвечает за выделение/освобождение памяти. Используется, например, в PODArray, Arena.
* Интерфейс отличается от std::allocator
* - наличием метода realloc, который для больших кусков памяти использует mremap;
* - передачей размера в метод free;
* - наличием аргумента alignment;
*/
class Allocator
{
private:
/** См. комментарий в HashTableAllocator.h
*/
static constexpr size_t MMAP_THRESHOLD = 64 * (1 << 20);
static constexpr size_t HUGE_PAGE_SIZE = 2 * (1 << 20);
static constexpr size_t MMAP_MIN_ALIGNMENT = 4096;
static constexpr size_t MALLOC_MIN_ALIGNMENT = 8;
public:
/// Выделить кусок памяти.
void * alloc(size_t size, size_t alignment = 0)
{
if (current_memory_tracker)
current_memory_tracker->alloc(size);
void * buf;
if (size >= MMAP_THRESHOLD)
{
if (alignment > MMAP_MIN_ALIGNMENT)
throw DB::Exception("Too large alignment: more than page size.", DB::ErrorCodes::BAD_ARGUMENTS);
buf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (MAP_FAILED == buf)
DB::throwFromErrno("Allocator: Cannot mmap.", DB::ErrorCodes::CANNOT_ALLOCATE_MEMORY);
/// См. комментарий в HashTableAllocator.h
if (size >= HUGE_PAGE_SIZE && 0 != madvise(buf, size, MADV_HUGEPAGE))
DB::throwFromErrno("HashTableAllocator: Cannot madvise with MADV_HUGEPAGE.", DB::ErrorCodes::CANNOT_ALLOCATE_MEMORY);
}
else
{
if (alignment <= MALLOC_MIN_ALIGNMENT)
{
buf = ::malloc(size);
if (nullptr == buf)
DB::throwFromErrno("Allocator: Cannot malloc.", DB::ErrorCodes::CANNOT_ALLOCATE_MEMORY);
}
else
{
buf = nullptr;
int res = posix_memalign(&buf, alignment, size);
if (0 != res)
DB::throwFromErrno("Cannot allocate memory (posix_memalign)", DB::ErrorCodes::CANNOT_ALLOCATE_MEMORY, res);
}
}
return buf;
}
/// Освободить память.
void free(void * buf, size_t size)
{
if (size >= MMAP_THRESHOLD)
{
if (0 != munmap(buf, size))
DB::throwFromErrno("Allocator: Cannot munmap.", DB::ErrorCodes::CANNOT_MUNMAP);
}
else
{
::free(buf);
}
if (current_memory_tracker)
current_memory_tracker->free(size);
}
/** Увеличить размер куска памяти.
* Содержимое старого куска памяти переезжает в начало нового.
* Положение куска памяти может измениться.
*/
void * realloc(void * buf, size_t old_size, size_t new_size, size_t alignment = 0)
{
if (old_size < MMAP_THRESHOLD && new_size < MMAP_THRESHOLD && alignment <= MALLOC_MIN_ALIGNMENT)
{
if (current_memory_tracker)
current_memory_tracker->realloc(old_size, new_size);
buf = ::realloc(buf, new_size);
if (nullptr == buf)
DB::throwFromErrno("Allocator: Cannot realloc.", DB::ErrorCodes::CANNOT_ALLOCATE_MEMORY);
}
else if (old_size >= MMAP_THRESHOLD && new_size >= MMAP_THRESHOLD)
{
if (current_memory_tracker)
current_memory_tracker->realloc(old_size, new_size);
buf = mremap(buf, old_size, new_size, MREMAP_MAYMOVE);
if (MAP_FAILED == buf)
DB::throwFromErrno("Allocator: Cannot mremap.", DB::ErrorCodes::CANNOT_MREMAP);
}
else
{
void * new_buf = alloc(new_size, alignment);
memcpy(new_buf, buf, old_size);
free(buf, old_size);
buf = new_buf;
}
return buf;
}
};