grnet/synnefo — pull request #197 by gkorf (2014-08-25 11:46:17+00:00)
Title: astakos: Lock holders when updating holdings

It is not safe to delete and re-insert holdings that have been locked,
because a second thread that has been blocked while retrieving the
same holdings will ultimately not get the deleted ones. Instead of
locking the holdings, we introduce a table to keep the holders and
lock these.