分类: C/C++
2007-03-25 16:19:55
以上程序只要稍微修改,就可以实现共享内存的管理,可以方便的使用标准库提供的容器。加上信号量 的锁机制。 以上为了学习而改写的SGI的stl二级分配算法实现的。以上代码存在一定的局限性。我另外完整实现了共享内存管理的STL标准的alloctor程序, 使用posix信号量加锁。目前应用在aix的xlC编译环境下。因为源码涉及公司的商业秘密,所以不能公开。但基本上以上源码已经体现了自己管理内存的 完整思路,供这方面需求的朋友一起学习研究用。
根据sgi 的STL源码的二级分配算法改写的内存池分配程序, 只要稍微修改就可以实现共享内存方式管理,使用C++标准库容器中的map,set,multimap,multiset测试通过,vector测试通不 过,原因是在内存回收的时候考虑的比较简单,vector每次分配内存个数不固定,回收也不固定,这样的话,程序还需要继续完善。
内存池管理程序源码如下:
#ifndef MY_ALLOCATOR_H_
#define MY_ALLOCATOR_H_
#include "stdafx.h"
#include
#include
namespace happyever
{
enum { NODENUMS = 2 };
union _Obj
{
union _Obj* M_free_list_link;
char M_client_data[1];
} ;
typedef union _Obj Obj;
struct _Cookie
{
int iShmKey; /* 共享内存键值 */
int iShmID; /* iShmKey对应的shmid */
int iSemKey; /* 锁信号键值 */
int iSemID; /* 锁信号标识 */
int iTotalsize; /* 容器总容量 */
void* pStartall; /* 共享内存自身地址 */
char* pStartfree; /* 自由空间的开始地址*/
char* pEndfree; /* 自由空间的结束地址*/
int iUseNum[NODENUMS];
/*用来存放free_list中节点的size*/
short sFreelistIndex[NODENUMS];
/*存放分配内存节点的链表*/
Obj* uFreelist[NODENUMS];
};
typedef struct _Cookie Cookie;
//Obj;
//Cookie;
static Cookie *pHead = NULL;
template
class MyAlloc
{
private:
static const int ALIGN = sizeof(Obj);
int round_up(int bytes);
int freelist_index(int bytes);
int freelist_getindex(int bytes);
char* chunk_alloc(int size, int *nobjs);
void* refill(int num,int n);
public:
// type definitions
typedef T value_type;
typedef T* pointer;
typedef const T* const_pointer;
typedef T& reference;
typedef const T& const_reference;
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
template
struct rebind
{
typedef MyAlloc other;
};
pointer address (reference value) const
{
return &value;
}
const_pointer address (const_reference value) const
{
return &value;
}
MyAlloc() throw()
{
std::cout<<"MyAlloc"<
MyAlloc(const MyAlloc& x) throw()
{
std::cout<<"const MyAlloc"<
template
MyAlloc (const MyAlloc& x) throw()
{
std::cout<<"const MyAlloc"<
~MyAlloc() throw()
{
std::cout<<"~MyAlloc"<
size_type max_size () const throw()
{
return std::numeric_limits
}
//void PrintFreelistAndCookie();
pointer allocate (size_type num, const void* = 0)
{
pointer ret = 0;
Obj** my_free_list;
Obj* result;
int index;
// print message and allocate memory with global new
std::cerr << "allocate " << num << " element(s)"
<< " of size " << sizeof(T) << std::endl;
index = freelist_index(sizeof(T));
if(index >= NODENUMS)
{
return NULL;
}
my_free_list = pHead->uFreelist + index;
//Lock(semid,LOCK_NUM);
result = *my_free_list;
if (result == 0)
{
ret = (pointer)refill((int)num, round_up(sizeof(T)));
}
else
{
*my_free_list = result->M_free_list_link;
ret = (pointer)result;
}
//UnLock(semid,LOCK_NUM);
pHead->iUseNum[index] = pHead->iUseNum[index] + (int)num;
if(0 == ret)
{
std::cerr << "alloc memory fail!" << std::endl;
exit(1);
}
std::cerr << " allocated at: " << (void*)ret << std::endl;
PrintFreelistAndCookie();
return ret;
}
void construct (pointer p, const T& value)
{
// initialize memory with placement new
new((void*)p)T(value);
}
void destroy (pointer p)
{
// destroy objects by calling their destructor
p->~T();
}
void deallocate (pointer p, size_type num)
{
Obj** my_free_list;
Obj* q ;
int index;
index = freelist_getindex(sizeof(T));
if(index >= NODENUMS)
{
std::cerr << "deallocate memory fail!" << std::endl;
exit(1);
}
my_free_list = pHead->uFreelist + index;
q = (Obj*) p;
//Lock(semid,LOCK_NUM);
/*这个地方可能会有问题*/
//for(int i=0 ;i<(int)num ; i++)
{
q->M_free_list_link = *my_free_list;
*my_free_list = q;
}
//UnLock(semid,LOCK_NUM);
pHead->iUseNum[index] = pHead->iUseNum[index] - (int)num;
std::cerr << "deallocate " << num << " element(s)"
<< " of size " << sizeof(T)
<< " at: " << (void*)p << std::endl;
PrintFreelistAndCookie();
}
};
template
int MyAlloc
{
int i;
i = bytes;
if(bytes < ALIGN)
{
i = ALIGN;
}
std::cout<<"round_up:bytes="< if (bytes_left >= total_bytes) return(result); template chunk = chunk_alloc(n, nobjs); counts = *nobjs; my_free_list = pHead->uFreelist + freelist_index(n); result = (Obj*)chunk; /*这个函数可以改写成自己的共享内存分配函数*/ static void InitShm() pHead->iTotalsize = sizeof(Cookie)+size; pHead->pStartall = pHead; for(i=0 ; i static void PrintFreelistAndCookie() std::cout<<"Cookie info :"< std::cout<<"nFreelist info :"< while(my_free_list->M_client_data != 0) using namespace std; int _tmain(int argc, _TCHAR* argv[]) m.insert(make_pair(string("Harry"), 32)); for (Iter p = m.begin(); p != m.end(); p++) Iter p = m.find("Harry"); /*p = m.find("Harry"); return 0; 以上程序在vs2005,vc6上测试通过。使用MinGW编译的时候只需要去掉vc的预编译头文件 #include "stdafx.h" 即可。 以上程序只要稍微修改,就可以实现共享内存的管理,可以方便的使用标准库提供的容器。加上信号量的锁机制。 以上为了学习而改写的SGI的stl二级分配算法实现的。以上代码存在一定的局限性。我另外完整实现了共享内存管理的STL标准的alloctor
程序,使用posix信号量加锁。目前应用在aix的xlC编译环境下。因为源码涉及公司的商业秘密,所以不能公开。但基本上以上源码已经体现了自己管理
内存的完整思路,供这方面需求的朋友一起学习研究用。
{
result = pHead->pStartfree;
pHead->pStartfree += total_bytes;
std::cout<<"chunk_alloc:total_bytes = "<
else if (bytes_left >= size)
{
counts = bytes_left/size;
total_bytes = size * counts;
result = pHead->pStartfree;
pHead->pStartfree += total_bytes;
*nobjs = counts;
std::cout<<"chunk_alloc:total_bytes = "<
else
{
/*还需要处理回收其他空闲freelist里面的空间*/
result = NULL;
}
};
void* MyAlloc
{
int counts = num;
int *nobjs = &counts;
char* chunk;
Obj** my_free_list;
Obj* result;
Obj* current_obj;
Obj* next_obj;
int i;
if(chunk == NULL)
{
return(chunk);
}
if (1 == counts)
{
return(chunk);
}
*my_free_list = next_obj = (Obj*)(chunk + n*num);
for (i = 1; ; i++)
{
current_obj = next_obj;
next_obj = (Obj*)((char*)next_obj + n);
if (counts - 1 == i)
{
current_obj->M_free_list_link = 0;
break;
}
else
{
current_obj->M_free_list_link = next_obj;
}
}
return(result);
};
{
int i,size=1000;
pHead = (Cookie*)malloc(sizeof(Cookie)+size);
pHead->pStartfree = (char*)pHead + sizeof(Cookie);
pHead->pEndfree = (char*)pHead + pHead->iTotalsize;
pHead->sFreelistIndex[i]=0;
pHead->uFreelist[i]=0;
pHead->iUseNum[i]=0;
}
}
{
int i,j;
Obj* my_free_list;
j=0;
std::cout<<"iUseNum["<iUseNum[i]<
if(my_free_list->M_client_data != 0)
{
{
j++;
my_free_list = my_free_list->M_free_list_link;
}
std::cout<<"free_list["<#include
{
happyever ::InitShm();
multimap
m.insert(make_pair(string("Mary"), 59));
m.insert(make_pair(string("Roger"), 18));
m.insert(make_pair(string("Nancy"), 37));
m.insert(make_pair(string("Mary"), 23));
typedef multimap
{
cout << p->first << "," << p->second << endl;
}
m.erase(p);
cout << "Harry is: " << p->second << "." << endl;*/
for (Iter p = m.begin(); p != m.end(); p++)
{
cout << p->first << "," << p->second << endl;
}
}