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通过全局重载new
和delete
操作符,实现堆区空间的分配和释放的跟踪记录
// Memory.h
#if TRACK_MEMORY
#ifdef PLATFORM_WINDOWS_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new(size_t size);_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new[](size_t size);_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new(size_t size, const char* desc);_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new[](size_t size, const char* desc);_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new(size_t size, const char* file, int line);_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new[](size_t size, const char* file, int line);void __CRTDECL operator delete(void* memory);
void __CRTDECL operator delete(void* memory, const char* desc);
void __CRTDECL operator delete(void* memory, const char* file, int line);
void __CRTDECL operator delete[](void* memory);
void __CRTDECL operator delete[](void* memory, const char* desc);
void __CRTDECL operator delete[](void* memory, const char* file, int line);#define hnew new(__FILE__, __LINE__) // 源文件、行号,用于跟踪进行内存分配的位置
#define hdelete delete#else#warning "Memory tracking not available on non-Windows platform"
#define hnew new
#define hdelete delete#endif#else#define hnew new
#define hdelete delete#endif
// Memory.cpp
#if TRACK_MEMORY && PLATFORM_WINDOWS// windows平台的MSVC编译器的标注和属性
_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new(size_t size)
{return Allocator::Allocate(size); // 分配一块大小为 size 字节的内存。
}_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new[](size_t size)
{return Allocator::Allocate(size);
}_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new(size_t size, const char* desc)
{return Allocator::Allocate(size, desc); // 分配一块大小为 size 字节的内存,并附带一个描述字符串。
}_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new[](size_t size, const char* desc)
{return Allocator::Allocate(size, desc);
}_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new(size_t size, const char* file, int line)
{return Allocator::Allocate(size, file, line); // 分配一块大小为 size 字节的内存,并记录文件名和行号。
}_NODISCARD _Ret_notnull_ _Post_writable_byte_size_(size) _VCRT_ALLOCATOR
void* __CRTDECL operator new[](size_t size, const char* file, int line)
{return Allocator::Allocate(size, file, line);
}void __CRTDECL operator delete(void* memory)
{return Allocator::Free(memory);
}void __CRTDECL operator delete(void* memory, const char* desc)
{return Allocator::Free(memory);
}void __CRTDECL operator delete(void* memory, const char* file, int line)
{return Allocator::Free(memory);
}void __CRTDECL operator delete[](void* memory)
{return Allocator::Free(memory);
}void __CRTDECL operator delete[](void* memory, const char* desc)
{return Allocator::Free(memory);
}void __CRTDECL operator delete[](void* memory, const char* file, int line)
{return Allocator::Free(memory);
}#endif
自定义内存分配接口
// Memory.h
#pragma once#include <map>
#include <mutex>// 用于记录整个程序内存分配的情况
struct AllocationStats
{size_t TotalAllocated = 0;size_t TotalFreed = 0;
};// 用于记录单个内存分配的信息
struct Allocation
{void* Memory = 0;size_t Size = 0;const char* Category = 0; // 描述信息,比如记录申请内存分配的代码的位置,该内存的用处等等
};// 对外接口,用于获取记录分配情况的静态对象(仅Memory.cpp可见)
namespace Memory
{const AllocationStats& GetAllocationStats();
}// Map Allocator 自定义的内存分配器,用于管理std::map的键值对的内存分配,
template <class T>
struct Mallocator
{typedef T value_type;Mallocator() = default;template <class U> constexpr Mallocator(const Mallocator <U>&) noexcept {}T* allocate(std::size_t n){
#undef max// 64位操作系统最大寻址内存值为2^64,因此要保证传入的n是小于这个的if (n > std::numeric_limits<std::size_t>::max() / sizeof(T))throw std::bad_array_new_length();if (auto p = static_cast<T*>(std::malloc(n * sizeof(T)))) {return p;}throw std::bad_alloc();}void deallocate(T* p, std::size_t n) noexcept {std::free(p);}
};struct AllocatorData
{// 2个自定义分配器,分别用于管理std::map中的 这种键值对的内存分配: // key: value:// const void* const -- Allocation// const char* const -- AllocationStatsusing MapAlloc = Mallocator<std::pair<const void* const, Allocation>>;using StatsMapAlloc = Mallocator<std::pair<const char* const, AllocationStats>>;using AllocationStatsMap = std::map<const char*, AllocationStats, std::less<const char*>, StatsMapAlloc>;// 两个std::map容器// key:内存地址;value: Allocation结构体,记录了内存的指针、大小、描述信息std::map<const void*, Allocation, std::less<const void*>, MapAlloc> m_AllocationMap;// key:描述信息;value: 内存总共分配数量、释放数量AllocationStatsMap m_AllocationStatsMap;std::mutex m_Mutex, m_StatsMutex;
};// 内存分配器接口定义
class Allocator
{
public:static void Init();static void* AllocateRaw(size_t size);static void* Allocate(size_t size);static void* Allocate(size_t size, const char* desc);static void* Allocate(size_t size, const char* file, int line);static void Free(void* memory);static const AllocatorData::AllocationStatsMap& GetAllocationStats() { return s_Data->m_AllocationStatsMap; }
private:inline static AllocatorData* s_Data = nullptr;
};
#include "Memory.h"#include <memory>
#include <map>
#include <mutex>#include "Log.h"
// 用于记录全局内存分配、释放的信息
static Hazel::AllocationStats s_GlobalStats;// 分配器是否正在进行初始化操作(应付多线程)
static bool s_InInit = false;// 初始化阶段,主要是分配一个静态的AllocatorData对象(lazy 初始化)
void Allocator::Init()
{if (s_Data)return;s_InInit = true;AllocatorData* data = (AllocatorData*)Allocator::AllocateRaw(sizeof(AllocatorData));new(data) AllocatorData(); // 定位new(placement new)在指定地址构造目标对象,并调用构造函数初始化,释放需要调用operator deletes_Data = data;s_InInit = false;
}// 利用malloc进行原始内存分配(即不会调用构造和析构),记得手动调用Allocator::free
void* Allocator::AllocateRaw(size_t size)
{return malloc(size);
}void* Allocator::Allocate(size_t size)
{// 如果一个线程正在执行Init()函数,分配请求用原始内存分配来处理if (s_InInit)return AllocateRaw(size);if (!s_Data)Init();void* memory = malloc(size);{std::scoped_lock<std::mutex> lock(s_Data->m_Mutex);Allocation& alloc = s_Data->m_AllocationMap[memory]; // 没有该key就创建,有就返回alloc.Memory = memory;alloc.Size = size;s_GlobalStats.TotalAllocated += size;}return memory;
}// 分配带有描述信息的内存,这个内存不仅要记录到总分配内存计数器中,还要把这种类型的内存单独进行计数
void* Allocator::Allocate(size_t size, const char* desc)
{if (!s_Data)Init();void* memory = malloc(size);{std::scoped_lock<std::mutex> lock(s_Data->m_Mutex);Allocation& alloc = s_Data->m_AllocationMap[memory];alloc.Memory = memory;alloc.Size = size;alloc.Category = desc;s_GlobalStats.TotalAllocated += size;if (desc)s_Data->m_AllocationStatsMap[desc].TotalAllocated += size; // 单独计数}return memory;
}
// line没用到,目前只想逐源文件记录内存分配量
void* Allocator::Allocate(size_t size, const char* file, int line)
{if (!s_Data)Init();void* memory = malloc(size);{std::scoped_lock<std::mutex> lock(s_Data->m_Mutex);Allocation& alloc = s_Data->m_AllocationMap[memory];alloc.Memory = memory;alloc.Size = size;alloc.Category = file;s_GlobalStats.TotalAllocated += size;s_Data->m_AllocationStatsMap[file].TotalAllocated += size;}return memory;
}void Allocator::Free(void* memory)
{if (memory == nullptr)return;{// map中有,计数更新并移除bool found = false;{std::scoped_lock<std::mutex> lock(s_Data->m_Mutex);auto allocMapIt = s_Data->m_AllocationMap.find(memory);found = allocMapIt != s_Data->m_AllocationMap.end();if (found) {const Allocation& alloc = allocMapIt->second;s_GlobalStats.TotalFreed += alloc.Size;if (alloc.Category)s_Data->m_AllocationStatsMap[alloc.Category].TotalFreed += alloc.Size;s_Data->m_AllocationMap.erase(memory);}}if (!found)LOG("Memory", "Memory block {0} not present in alloc map", memory);}free(memory);
}namespace Memory {const AllocationStats& GetAllocationStats() { return s_GlobalStats; }
}
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