public void pageRead(final int bytesRead,
                       final long readStartedAtNs) {
    assert bytesRead >= 0 : "bytesRead must be >=0, " + bytesRead;
    totalBytesRead.addAndGet(bytesRead);
    if (MEASURE_TIMESTAMPS) {
      totalPagesReadNs.addAndGet(System.nanoTime() - readStartedAtNs);
    }
  }
public void pageRead(final int bytesRead,
                       final long readStartedAtNs)