Re: notification of connection closure to database backends.

["Kurt D. Zeilenga" <Kurt@OpenLDAP.org>]

At 06:07 PM 6/22/99 +0200, Bastiaan Bakker wrote:
>Hi,
>
>While working on the CORBA database backend I noticed that there's no
>way for a backend to receive a notification of the closing of a client
>connection. In most cases this is not a problem, but the CORBA backend
>needs to maintain state on a per connection basis. If it doesn't know
>when a connection closes, it cannot release its state nor notify the
>backend server to release any resources (both CPU and memory) in use for
>that connection.
>The way I would like to add notification support is to include a NULL
>terminated list notification callback functions in each connection
>structure. Each backend interested in the destruction of the connection
>can add its own callback function to this list. The
>'connection_destroy()' operation shall call each of the functions in the
>list with a pointer to the connection as argument.
>The overhead of this feature is small: addition of a void** member to
>the ldap_conn struct and an 'if !=NULL call all in the list' in the
>'connection_destroy()' method.
>If anyone has objections to this approach or knows a better way to do
>the same, please let me know or I'll start coding.

I think I'd rather extend the existing backend interface to support
this...

I suggest adding two additional functions that can be registered
by backend ends:
	(be->be_connection_init)(conn) and
	(be->be_connection_destroy)().

connection_init(fd), AFTER intializing the connection, would call
be_connection_init(conn) which in turn would call the provided
be->be_connection_init(conn) routines.

connection_destroy(), BEFORE destorying the connection, would call
be_connection_destory(conn) which in turn would call the provided
be->be_destory_init(conn) routines.

	Kurt