linux 中msgque的使用demo

server端，默认为阻塞模式，msgsnd 超过队列的的缓冲后会报错误。直到队列可存放数据。

/*******************************************************************************
* function name : msgserver_handle 
* description   : heartbeat function ,if receive new data ,clear counter,or,
*                 call heatbeat main func
* param[in]     : task_table[4]
* param[out]    : none
* return        : none
*******************************************************************************/
int  *msgserver_handle (void *arg)
{

    int id = 0;

    static char pthread_flg = 0;

    if(pthread_flg ==1)
        return 0;
    pthread_flg = 1;
    key_t key = ftok("/tmp",66);
    id = msgget(key,IPC_CREAT | 0666);
    if(id == -1)
    {
        printf("create msg error \n");
        return 0;
    }

    while(videoIsRun==1)
    {

        ckxmsg.mtype = 1;

            if(running ==1){

            LOG1("send msg %s %d\n", ckxmsg.mtext,ckxmsg.time_difference);
            if(msgsnd(id,(void *)&ckxmsg,512,0) < 0)
            {
                printf("send msg error \n");
                return 0;
            }
            memset((void *)&ckxmsg,0,sizeof(ckxmsg));
            running =0;
        }
        usleep(10000);
        if(strncmp(msg,"QUIT",4) == 0)
            break;
    }
    if(msgctl(id,IPC_RMID,NULL) < 0)
    {
        printf("del msg error \n");
        return 0;
    }
    return 0;

}

客户端 使用非阻塞模式实时读取，没有数据时返回-1，receive  msg error，在qt中使用
void Mainframe::ReadsharedMemoryFromcamera()
{
  static char accessflg =0;
  static unsigned int readcnt =0;

  if(accessflg == 0){
      accessflg = 1 ;

      key_t key = ftok("/tmp",66);
      id = msgget(key,0666|IPC_CREAT);
        if(id == -1)
      {
          qDebug()<<"open msg error \n";

      }
        qDebug()<<"open msgget id  " <<id ;
        label_detec_value->setText("Detecting");
    }
  readcnt ++;
  if(readcnt >= 10){
    readcnt = 10;
       memset(ckxmsg.mtext,0,512);
      if(msgrcv(id,(void *)&ckxmsg,512,1,IPC_NOWAIT ) < 0)//no wait 
      {
           qDebug()<<"receive  msg error \n";

      }else {

            qDebug() << "receive data is "<< ckxmsg.mtext ;
            if(0 == memcmp(ckxmsg.mtext,"exsist",6)){
                QString str_e(ckxmsg.mtext);
                label_detec_value->setText(str_e);

                }
            else {
                label_detec_value->setText("Detecting"); 
                }

        }

    }

}