The active count is incremented for every add and delete. It is never decremented so any update would result in a change. In my actual algorithms, all my lists are in shared or common memory objects so all the pointers are 64 bit and I use +2 variations on the PLO. In this case, I use a counter with 2 full words on a double word boundary. The first full word is the change count and it's always incremented. The second full word is element count and it's is incremented for each add and decremented for each deleted. I load the counter with a LG and then use ALG and AL or SL to manipulate the high or low word.
Kenneth -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Shmuel Metz (Seymour J.) Sent: Wednesday, November 13, 2013 7:29 AM To: [email protected] Subject: Re: Serialization without Enque In <[email protected]>, on 11/12/2013 at 10:34 PM, Kenneth Wilkerson <[email protected]> said: >Actually, the algorithm performs well for read-often, write-rarely list >because the active chain count does not change and therefore there are >relatively infrequent re-drives. What happens if the is an intervening add and also an intervening remove, leaving no net change in the active chain count even though the chain itself has changed? -- Shmuel (Seymour J.) Metz, SysProg and JOAT ISO position; see <http://patriot.net/~shmuel/resume/brief.html> We don't care. We don't have to care, we're Congress. (S877: The Shut up and Eat Your spam act of 2003) ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
