LCUP, persistent search

["Howard Chu" <hyc@highlandsun.com>]

The uidNumber thread got me thinking about implementing mutexes from
application level. Using modify to atomically toggle a lock attribute works,
and multiple clients can wait on a lock using a persistent search to notify
them when it's released. However, the waiting clients would then all be
notified at once, and thrash the server while they try to acquire the lock.
Is there a flag for the LCUP persistent search control to imply a round-robin
style of service, i.e. if multiple clients have the same search outstanding,
results will only be forwarded to one client at a time? Would it be worth
suggesting?

The other problem that this doesn't fix is, if the client currently holding
the lock goes away, nobody else can acquire it. If the lock attribute was
some kind of dynamic attribute instead, you could fix that too, automatically
resetting it when the setting client connection closed.

  -- Howard Chu
  Chief Architect, Symas Corp.       Director, Highland Sun
  http://www.symas.com               http://highlandsun.com/hyc
  Symas: Premier OpenSource Development and Support