记录锁

int base_class::getWriteLock(string& filename)
{
    int fd=open(filename.c_str(),O_RDWR|O_CREAT,S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
    if(fd<0)
    {
        cerr<<"open "<<filename<<"fail!"<<endl;
        return -1;
    }
    struct flock fl;

    fl.l_type=F_WRLCK;
    fl.l_start=0;
    fl.l_whence=SEEK_SET;
    fl.l_len=0;
    int retval=fcntl(fd,F_SETLK,&fl);
    if(retval==-1&& (errno==EACCES||errno==EAGAIN))
    {
        fcntl(fd,F_GETLK,&fl);
        cerr<<"进程已存在 pid:"<<fl.l_pid<<endl;
    }
    return retval;
}