(ITS#4546) [enhancement] discard cached connections when rebinding with different identity

[ando@sys-net.it]

Full_Name: Pierangelo Masarati
Version: HEAD
OS: irrelevant
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (87.28.220.33)
Submitted by: ando


When rebinding on an already bound client connection, back-ldap creates a new
cached connection with the same connection pointer but with a different
identity.  The existing cached connection with the same connection pointer and
the original identity is left in the connection tree until the client unbinds. 
This may be useful if a limited set of users repeatedly binds on the same
connection, but in general it wastes resources (and a new connection to the
target has to be generated anyway for each bind to avoid race conditions).

A statement "single-conn {TRUE|FALSE}" is added to back-ldap; it forces all
existing cached connections for that client connection to be flushed before
storing the new one during a rebind.

p.