UNIX下共亨内存

//*********************************************
//   Version:     1.0.0
//    Author:    
// Copyright:     copyleft,free
//   Purpose:     SharedMem
//      Date:     2004-9-3
//*********************************************

#ifndef CSHAREDMEM_H_
#define CSHAREDMEM_H_

#include
#include
#include
#include
#include
#include
#include

#include
#include
#include
#include

class CSharedMem
{
public:
 union  semun
 {
  int  val;
  struct  semid_ds   *buf;
  unsigned short int *array;
  struct   seminfo   *__buf;
 };

 CSharedMem();
 ~CSharedMem();

private: 
 //生成信号量 
 int Create_Sem(key_t key);
 
 //删除信号量 
 void Delete_sem();
 
 int p();
 int v();
 
 int    m_nSegSize;    //共享内容大小
 char*  m_pszContent;  //映射区指针
 int    m_nSemid;      //创建信号Key 
 pthread_mutex_t   m_hMutex; //线程锁
public:
 bool  InitSegSize( int nSegSize=1024 );
 bool  Read(char* pszContent, int nReadByteNum, bool bDeleteContent=true);
 bool  Writer(char* pszContent, int nWriterByteNum);
};

#endif //CSHAREDMEM_H_

 

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//*********************************************
//   Version:     1.0.0
//    Author:    
// Copyright:     copyleft,free
//   Purpose:     SharedMem
//      Date:     2004-9-3
//*********************************************

#include "SharedMem.h"

CSharedMem::CSharedMem()
{
 m_pszContent = NULL;
 /* 用默认属性初始化一个互斥锁对象*/
 pthread_mutex_init (&m_hMutex,NULL);
 printf("\nCSharedMem Start ...");
}

CSharedMem::~CSharedMem()
{
 munmap( m_pszContent, sizeof(char)*m_nSegSize);
 printf(" \n umap OK \n");
 Delete_sem(); 
 pthread_mutex_destroy(&m_hMutex);
 printf("\nCSharedMem End \n");
}

//生成信号量
int CSharedMem::Create_Sem(key_t kKey)
{
 union semun sem ; 
 sem.val=0; 
 m_nSemid = semget(IPC_PRIVATE, 1, IPC_CREAT|0666); 
 if (m_nSemid == -1)
 { 
  printf(" create semaphore error\n" ); 
  return -1; 
 } 
 //初始化信号量 
 semctl(m_nSemid, 0, SETVAL, sem); 
 return m_nSemid; 
}

//删除信号量 
void CSharedMem::Delete_sem()
{
 union semun sem ; 
 sem.val=0; 
 semctl(m_nSemid, 0, IPC_RMID, 0); 
}

int CSharedMem::p()
{
 //struct sembuf sops={0, +1,IPC_NOWAIT}; 
 //return(semop(m_nSemid, &sops, 1)); 
 printf("\n开始进入锁定...\n");
 pthread_mutex_lock(&m_hMutex);  
 printf("...已经锁定\n");
}

int CSharedMem::v()
{
 //struct sembuf sops={0, -1,IPC_NOWAIT}; 
 //return(semop(m_nSemid, &sops, 1));
 printf("\n开始进入解锁...\n");
 pthread_mutex_unlock(&m_hMutex);
 printf("...已经解锁\n");
}

bool CSharedMem::InitSegSize( int nSegSize )
{
 // 初始化信号量
 key_t  kKey;
 kKey = ftok("/", 0);
 int nRet = Create_Sem( kKey );
 if( nRet == -1 )
  return false;

 char* pFileName = "./SharedMem1111";
 m_nSegSize = nSegSize;

 // 移至文件尾,加上'\0'字符
 int fd = open(pFileName, O_CREAT|O_APPEND|O_RDWR, 0777);
 lseek(fd, sizeof(char)*m_nSegSize-1, SEEK_SET);
 write(fd, "", 1);
 
 void* pVoid = mmap( NULL, sizeof(char)*m_nSegSize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 close(fd);

 if( pVoid == MAP_FAILED )
 {
  printf(" Mmap ERROR 1\n");
  return false;
 }
 m_pszContent = (char*)pVoid;

 //strncpy(m_pszContent, "abcdef", 5); 
 printf(" \n initiallize over:%s \n",m_pszContent);
 return true;
}

bool CSharedMem::Read(char* pszContent, int nReadByteNum, bool bDeleteContent)
{
 p();
 memcpy(pszContent, m_pszContent, nReadByteNum);
 pszContent[nReadByteNum] = '\0';

 if( bDeleteContent )
  memset(m_pszContent, '\0', bDeleteContent);
 v();
 return  true;

}

bool CSharedMem::Writer(char* pszContent, int nWriterByteNum)
{
 p();
 strncat(m_pszContent, pszContent, nWriterByteNum);
 v();
 return true;
}

 

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