Method read_random

src/client/SyntheticClient.cc:2407–2500

int SyntheticClient::read_random(string& fn, int size, int rdsize)   // size is in MB, wrsize in bytes
{
  UserPerm perms = client->pick_my_perms();
  uint64_t chunks = (uint64_t)size * (uint64_t)(1024*1024) / (uint64_t)rdsize;
  int fd = client->open(fn.c_str(), O_RDWR, perms);
  dout(5) << "reading from " << fn << " fd " << fd << dendl;

  if (fd < 0) return fd;
  int offset = 0;
  char * buf = NULL;

  for (unsigned i=0; i<2000; i++) {
    if (time_to_stop()) break;

    bool read=false;

    time_t seconds;
    time( &seconds);
    srand(seconds);

    // use rand instead ??
    double x = drand48();

    // cleanup before call 'new'
    if (buf != NULL) {
	delete[] buf;
	buf = NULL;
    }
    if (x < 0.5) {
        buf = new char[rdsize]; 
        memset(buf, 1, rdsize);
        read=true;
    } else {
        buf = new char[rdsize+100];   // 1 MB
        memset(buf, 7, rdsize);
    }
    
    if (read) {
        offset=(rand())%(chunks+1);
        dout(2) << "reading block " << offset << "/" << chunks << dendl;

        int r = client->read(fd, buf, rdsize, offset*rdsize);
        if (r < rdsize) {
	  dout(1) << "read_file got r = " << r << ", probably end of file" << dendl;
	}
    } else {
      dout(2) << "writing block " << offset << "/" << chunks << dendl;

      // fill buf with a 16 byte fingerprint
      // 64 bits : file offset
      // 64 bits : client id
      // = 128 bits (16 bytes)

      offset=(rand())%(chunks+1);
      uint64_t *p = (uint64_t*)buf;
      while ((char*)p < buf + rdsize) {
	*p = offset*rdsize + (char*)p - buf;      
	p++;