shared memory 小程式 @ hedgezzz的部落格

static datafeed *conf;
#define STATE_FILE "/datafeed.shared"

    int shm_fd;
    if((shm_fd = shm_open(STATE_FILE, (O_CREAT | O_EXCL | O_RDWR),
                       (S_IREAD | S_IWRITE))) > 0 ) {
        ; /* We are the first instance */
    }
    else if((shm_fd = shm_open(STATE_FILE, (O_CREAT | O_RDWR),
                        (S_IREAD | S_IWRITE))) < 0)
    {
        printf("Could not create shm object. %s\n", strerror(errno));
        exit( 0 ) ;
    }
    int iTotalByte = sizeof(datafeed)*ARRAYSIZE ;
    ftruncate(shm_fd, iTotalByte );
    conf = (datafeed*) mmap(0, iTotalByte , (PROT_READ | PROT_WRITE), MAP_SHARED, shm_fd, 0) ;
    if(conf == MAP_FAILED)
    {
        printf(" mmap error ....\n") ;
        exit( 0 ) ;
    }

static futuresdatafeed *conf;
#define STATE_FILE "/datafeed.shared" // IF

    int shm_fd;

    if((shm_fd = shm_open(STATE_FILE, (O_RDWR),
                    (S_IREAD | S_IWRITE))) < 0) {
        printf("Could not create shm object. %s\n", strerror(errno));
        exit(0) ;
    }
    int iTotalByte = sizeof(futuresdatafeed)*ARRAYSIZE ;
    ftruncate(shm_fd, iTotalByte );
    conf = (futuresdatafeed *)mmap(0, iTotalByte , (PROT_READ | PROT_WRITE), MAP_SHARED, shm_fd, 0) ;
    if(conf == MAP_FAILED)
    {
        printf("error in mmap \n") ;
        exit(0) ;
    }