On Saturday, 01/14/2006 at 09:38 PST, "Harding, Mike" <[EMAIL PROTECTED]> wrote: > Sorry for jumping into this so late, but I wouldn't rule out shared segments > and would tend either to go that way or dataspaces. Bill Stephens was > incorrect - you can define a segment as shared writable, I've seen a couple of > apps built that way. If you have more than one writer you'll need a locking > mechanism (one I've seen used the first doubleword of the segment as a > compare&swap lock) as well as a mechanism for overriding the lock in case its > holder crashes. As for Bill's other concern it's your segment, you can define > it wherever you like and use diag64 services for finding/attaching it.
A robust implementation of a shared R/W DCSS access method makes the locking and lock override mechanism somewhat difficult. One of my early assignments at IBM was to work on the GCS recovery machine, whose primary purpose in life was to provide the needed lock release and data structure cleanup. Not fun. Alan Altmark z/VM Development IBM Endicott
