C++ 封装私有堆（Private Heap）
Private Heap 是 Windows 提供的一种内存内存机制，对于那些需要频繁分配和释放动态内存的应用程序来说，Private Heap 是提高应用程序性能的一大法宝，使用它能降低 new / malloc 的调用排队竞争以及内存空洞。Private Heap 的原理及应用的资料很多，这里就不一一介绍了，常用的 Private Heap API 有以下几个，具体介绍请参考帮助文档：
HeapCreate();
HeapDestroy();
HeapAlloc();
HeapReAlloc();
HeapSize();
HeapFree();
HeapCompact();
由于是 C 风格的 API，使用起来比较繁琐，因此本座在闲暇之余用 C++ 对这些 API 进行了封装，主要包括两个类：
- CPrivateHeap：自动创建和销毁进程私有堆，每一个该类的对象都代表一个私有堆，所以该类对象的特点是: 一般生命周期都比较长，通常作为全局对象, 其他类的静态成员对象或者一些长生命周期类对象的成员。
- CPrivateHeapBuffer<T>：在私有堆中自动分配和释放指定大小的内存，一般用于在函数体内分配和释放局部作用域的堆内存，从而避免对 CPrivateHeap::Alloc() 和 CPrivateHeap::Free() 的调用。
#pragma once
class CPrivateHeap
{
public:
enum EnCreateOptions
{
CO_DEFAULT = 0,
CO_NO_SERIALIZE = HEAP_NO_SERIALIZE,
CO_GENERATE_EXCEPTIONS = HEAP_GENERATE_EXCEPTIONS,
CO_NOSERIALIZE_GENERATEEXCEPTIONS
= HEAP_NO_SERIALIZE |
HEAP_GENERATE_EXCEPTIONS
};
enum EnAllocOptions
{
AO_DEFAULT = 0,
AO_ZERO_MEMORY = HEAP_ZERO_MEMORY,
AO_NO_SERIALIZE = HEAP_NO_SERIALIZE,
AO_GENERATE_EXCEPTIONS = HEAP_GENERATE_EXCEPTIONS,
AO_ZEROMEMORY_NOSERIALIZE
= HEAP_ZERO_MEMORY |
HEAP_NO_SERIALIZE,
AO_ZEROMEMORY_GENERATEEXCEPTIONS
= HEAP_ZERO_MEMORY |
HEAP_GENERATE_EXCEPTIONS,
AO_NOSERIALIZE_GENERATESEXCEPTIONS
= HEAP_NO_SERIALIZE |
HEAP_GENERATE_EXCEPTIONS,
AO_ZEROMEMORY_NOSERIALIZE_GENERATESEXCEPTIONS
= HEAP_ZERO_MEMORY |
HEAP_NO_SERIALIZE |
HEAP_GENERATE_EXCEPTIONS
};
enum EnReAllocOptions
{
RAO_DEFAULT = 0,
RAO_ZERO_MEMORY = HEAP_ZERO_MEMORY,
RAO_NO_SERIALIZE = HEAP_NO_SERIALIZE,
RAO_GENERATE_EXCEPTIONS = HEAP_GENERATE_EXCEPTIONS,
RAO_REALLOC_IN_PLACE_ONLY = HEAP_REALLOC_IN_PLACE_ONLY,
RAO_ZEROMEMORY_NOSERIALIZE
= HEAP_ZERO_MEMORY |
HEAP_NO_SERIALIZE,
RAO_ZEROMEMORY_GENERATEEXCEPTIONS
= HEAP_ZERO_MEMORY |
HEAP_GENERATE_EXCEPTIONS,
RAO_ZEROMEMORY_REALLOCINPLACEONLY
= HEAP_ZERO_MEMORY |
HEAP_REALLOC_IN_PLACE_ONLY,
RAO_NOSERIALIZE_GENERATESEXCEPTIONS
= HEAP_NO_SERIALIZE |
HEAP_GENERATE_EXCEPTIONS,
RAO_NOSERIALIZE_REALLOCINPLACEONLY
= HEAP_NO_SERIALIZE |
HEAP_REALLOC_IN_PLACE_ONLY,
RAO_GENERATESEXCEPTIONS_REALLOCINPLACEONLY
= HEAP_GENERATE_EXCEPTIONS |
HEAP_REALLOC_IN_PLACE_ONLY,
RAO_ZEROMEMORY_NOSERIALIZE_GENERATESEXCEPTIONS
= HEAP_ZERO_MEMORY |
HEAP_NO_SERIALIZE |
HEAP_GENERATE_EXCEPTIONS,
RAO_ZEROMEMORY_NOSERIALIZE_REALLOCINPLACEONLY
= HEAP_ZERO_MEMORY |
HEAP_NO_SERIALIZE |
HEAP_REALLOC_IN_PLACE_ONLY,
RAO_ZEROMEMORY_GENERATESEXCEPTIONS_REALLOCINPLACEONLY
= HEAP_ZERO_MEMORY |
HEAP_GENERATE_EXCEPTIONS |
HEAP_REALLOC_IN_PLACE_ONLY,
RAO_NOSERIALIZE_GENERATESEXCEPTIONS_REALLOCINPLACEONLY
= HEAP_NO_SERIALIZE |
HEAP_GENERATE_EXCEPTIONS |
HEAP_REALLOC_IN_PLACE_ONLY,
RAO_ZEROMEMORY_NOSERIALIZE_GENERATESEXCEPTIONS_REALLOCINPLACEONLY
= HEAP_ZERO_MEMORY |
HEAP_NO_SERIALIZE |
HEAP_GENERATE_EXCEPTIONS |
HEAP_REALLOC_IN_PLACE_ONLY
};
enum EnSizeOptions
{
SO_DEFAULT = 0,
SO_NO_SERIALIZE = HEAP_NO_SERIALIZE
};
enum EnFreeOptions
{
FO_DEFAULT = 0,
FO_NO_SERIALIZE = HEAP_NO_SERIALIZE
};
enum EnCompactOptions
{
CPO_DEFAULT = 0,
CPO_NO_SERIALIZE = HEAP_NO_SERIALIZE
};
public:
PVOID Alloc(DWORD size, EnAllocOptions options = AO_DEFAULT)
{return ::HeapAlloc(m_heap, options, size);}
PVOID ReAlloc(PVOID pvmem, DWORD size, EnReAllocOptions options = RAO_DEFAULT)
{return ::HeapReAlloc(m_heap, options, pvmem, size);}
DWORD Size(PVOID pvmem, EnSizeOptions options = SO_DEFAULT)
{return (DWORD)::HeapSize(m_heap, options, pvmem);}
BOOL Free(PVOID pvmem, EnFreeOptions options = FO_DEFAULT)
{return ::HeapFree(m_heap, options, pvmem);}
DWORD Comapct(EnCompactOptions options = CPO_DEFAULT)
{return (DWORD)::HeapCompact(m_heap, options);}
BOOL IsValid() {return m_heap != NULL;}
public:
CPrivateHeap(EnCreateOptions options = CO_DEFAULT, DWORD initsize = 0, DWORD maxsize = 0)
{m_heap = ::HeapCreate(options, initsize, maxsize);}
~CPrivateHeap() {if(IsValid()) ::HeapDestroy(m_heap);}
private:
CPrivateHeap(const CPrivateHeap&);
CPrivateHeap operator = (const CPrivateHeap&);
private:
HANDLE m_heap;
};
template<class T>
class CPrivateHeapBuffer
{
public:
CPrivateHeapBuffer( CPrivateHeap& heap,
DWORD size = 0,
CPrivateHeap::EnAllocOptions allocoptions = CPrivateHeap::AO_DEFAULT,
CPrivateHeap::EnFreeOptions freeoptions = CPrivateHeap::FO_DEFAULT)
: m_hpPrivate(heap)
, m_opFree(freeoptions)
{
ASSERT(m_hpPrivate.IsValid());
m_pvMemory = (T*)m_hpPrivate.Alloc(size * sizeof(T), allocoptions);
}
~CPrivateHeapBuffer() {m_hpPrivate.Free(m_pvMemory, m_opFree);}
T* ReAlloc(DWORD size, CPrivateHeap::EnReAllocOptions options = CPrivateHeap::RAO_DEFAULT)
{return m_pvMemory = (T*)m_hpPrivate.ReAlloc(m_pvMemory, size * sizeof(T), options);}
DWORD Size(CPrivateHeap::EnSizeOptions options = CPrivateHeap::SO_DEFAULT)
{return m_hpPrivate.Size(m_pvMemory, options);}
operator T* () const {return m_pvMemory;}
private:
CPrivateHeapBuffer(const CPrivateHeapBuffer&);
CPrivateHeapBuffer operator = (const CPrivateHeapBuffer&);
private:
CPrivateHeap& m_hpPrivate;
T* m_pvMemory;
CPrivateHeap::EnFreeOptions m_opFree;
};
typedef CPrivateHeapBuffer<BYTE> CPrivateHeapByteBuffer;
typedef CPrivateHeapBuffer<TCHAR> CPrivateHeapStrBuffer;
上述代码看起来挺复杂，但使用起来却是异常简单的，请看下面的使用示例：
// 全局可见的 Heap
CPrivateHeap g_heap;
class MyClass
{
private:
// 与类实例生命周期一致的 Heap
CPrivateHeap m_heap;
// 仅类内部可见的 Heap
static CPrivateHeap sm_heap;
public:
void test_m_eap()
{
// 无需显式释放堆内存
CPrivateHeapStrBuffer buff(m_heap, 32);
lstrcpy(buff, _T("失败乃成功之母"));
DWORD size = buff.Size();
buff.ReAlloc(40 * sizeof(TCHAR));
size = buff.Size();
std::cout << (TCHAR*)buff << '\n';
}
static void test_sm_eap()
{
CPrivateHeapStrBuffer buff(sm_heap, 32);
lstrcpy(buff, _T("失败乃成功之母"));
DWORD size = buff.Size();
buff.ReAlloc(40 * sizeof(TCHAR));
size = buff.Size();
std::cout << (TCHAR*)buff << '\n';
}
};
void test_g_heap()
{
// 如果不使用 CPrivateHeapBuffer<T> 来封装堆内存
ASSERT(g_heap.IsValid());
TCHAR* pch = (TCHAR*)g_heap.Alloc(32 * sizeof(TCHAR));
lstrcpy(pch, _T("失败乃成功之母"));
DWORD size = g_heap.Size(pch);
g_heap.ReAlloc(pch, 40 * sizeof(TCHAR));
size = g_heap.Size(pch);
std::cout << pch << '\n';
// 需要显式释放堆内存
g_heap.Free(pch);
}
int _tmain(int argc, _TCHAR* argv[])
{
test_g_heap();
MyClass::test_sm_eap();
MyClass c;
c.test_m_eap();
return 0;
}
