'Write index marker i.'

def _MaybeWriteIndex(self, i, ts, mutation_pool):

    if ((i > self._max_indexed) and ((i % self.INDEX_SPACING) == 0)):
        if (ts[0] < (rdfvalue.RDFDatetime.Now() - self.INDEX_WRITE_DELAY).AsMicroSecondsFromEpoch()):
            try:
                mutation_pool.Set(self.collection_id, (self.INDEX_ATTRIBUTE_PREFIX + ('%08x' % i)), ('%06x' % ts[1]), timestamp=ts[0], replace=True)
                self._index[i] = ts
                self._max_indexed = max(i, self._max_indexed)
            except access_control.UnauthorizedAccess:
                pass
