windows下利用文件映射实现共享内存

windows下利用文件映射实现共享内存的办法比较简单，下面是实现代码，细节用注释说明．
调用类似linux下shm的操作．该类没有进行太多的测试，欢迎提出问题和bug～～：）

#include <windows.h>#include <string>#include <iostream>#include <assert.h>using std::string;using std::cout;using std::endl;#pragma warning(disable: 4311)class shareMemory{private: LPWSTR shm_name_u; bool  is_create_file; void * sh_base; HANDLE semaphore; HANDLE file_mapping; int  addr_len;public:/*create＿file用来说明是用磁盘文件映射还是页文件映射，如果用磁盘文件映射，共享内存不会出现存储器release后出现违规访问的问题，但是会在磁盘上建立一个文件，文件的名称由参数shm＿name给定．如果用页文件映射，则不会在磁盘上建立一个文件*/ shareMemory(const string& shm_name, bool create_file=false):is_create_file(create_file) {     const char * _c_shm_name = shm_name.c_str();  int _size =(int)shm_name.length()+1;  shm_name_u=(LPWSTR)malloc(_size*2);  MultiByteToWideChar(CP_ACP,0,_c_shm_name,_size,shm_name_u,_size);  semaphore =  CreateSemaphore(NULL,1,1,NULL);  sh_base = NULL;  file_mapping = INVALID_HANDLE_VALUE; } void * shm_open(void* addr,const int length, DWORD protect) {   addr_len = length;  HANDLE _file_handle = INVALID_HANDLE_VALUE;  if(is_create_file)  {  _file_handle=   CreateFile(shm_name_u,GENERIC_READ|GENERIC_WRITE,0,   NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,0);#ifdef _DEBUG  if(_file_handle==INVALID_HANDLE_VALUE)   cout<<"can not create file! we use page file instead!";#endif  //end _DEBUG  }/*打开指定名称的文件映射，如果不存在则创建一个*/  file_mapping = OpenFileMapping(PAGE_READWRITE,false,shm_name_u );  if(file_mapping!=NULL)    goto file_mapping_exist;   file_mapping =    CreateFileMapping(_file_handle,NULL,PAGE_READWRITE,   0,length,shm_name_u);#ifdef _DEBUG   assert(file_mapping);#endif    if(file_mapping==NULL)    return NULL;file_mapping_exist:  sh_base = MapViewOfFileEx(file_mapping,protect,0,0,length,addr);  CloseHandle(_file_handle);  return sh_base; }        /*往共享内存中写数据，返回写出数据的字节个数*/ int  shm_write(void *dest, void * src, int size) {     if(!check_adress(dest))   return -1;  int _write_count = (int)sh_base+addr_len - (int)dest;  if(_write_count>size)   _write_count = size;/*利用semaphore进行保护映射的区域（同一进程的不同线程调用时候才进行保护）*/  WaitForSingleObject(semaphore,INFINITE);  memcpy(dest,src,_write_count);   ReleaseSemaphore(semaphore,1,NULL);  FlushViewOfFile(sh_base,_write_count);  return _write_count; } /*从共享内存中读数据，返回读出的数据字节个数＊*/int  shm_read(void* src, void * dest, int size) {  if(!check_adress(src))   return -1;    int _read_count = (int)sh_base+addr_len -(int) src; if(_read_count>size)  _read_count = size; memcpy(dest,src,_read_count); return _read_count; } ~shareMemory() {    UnmapViewOfFile(sh_base);   free(shm_name_u);   CloseHandle(semaphore);   CloseHandle(file_mapping); }private :/*进行地址检测*/ bool check_adress(void* addr) { if( ( (int)addr <(int)sh_base) || ((int)addr > (int)sh_base+addr_len) )  {   SetLastError(ERROR_ACCESS_DENIED);#ifdef _DEBUG   printf("access denied,the destination address out of the map view!");#endif //_DEBUG   return  false;  } return true; }};

测试：
写进程的主函数：

int main(){ shareMemory sm("boost", false); void * bs = sm.shm_open(NULL,1000*4,FILE_MAP_WRITE); if(bs==NULL)  return -1; int a[10]; for(int i=0; i<10; ++i)  a[i] = i; sm.shm_write(bs,a,10*4); Sleep(100000);}

读进程的主函数：

int main(){ shareMemory sm("boost", false); void * bs = sm.shm_open(NULL,1000,FILE_MAP_READ); if(bs==NULL) {   cout<<"null";  return -1; }    int b[10]; sm.shm_read(bs,b,10*4); for(int i=0; i<10; ++i)  cout<<b[i]<<"  ";}

/////////////////////////////////////////////////////另一个例子//////////////////////////////////////////////////////

http://blog.csdn.net/zhao_fu_lu/article/details/41730699