On Sun, Aug 2, 2009 at 3:20 PM, Mark Volkmann<r.mark.volkm...@gmail.com> wrote: > > The doc for commute says "At the commit point of the transaction, sets > the value of ref to be: > (apply fun most-recently-committed-value-of-ref args)". > > Looking at the source code in LockingTransaction.java, that doesn't > seem to always be the case. I see this: > f.fn.applyTo(RT.cons(vals.get(ref), f.args)) > > vals is a HashMap of in-transaction values, not most recently committed > values. > > Inside a transaction, Refs get in-transaction values if you do a > ref-set or alter on them. > Within a transaction you can ref-set or alter a Ref and then do a > commute on the same Ref. > You can't reverse the order. Once you do a commute on a Ref, you can't > do a ref-set or alter on it in the same transaction. > > During transaction commit and immediately before the commute functions > for the Ref are called, it determines whether the Ref has an > in-transaction value, meaning that ref-set or alter was called on it. > If it does not then the most recently committed value for the Ref is > used for the in-transaction value. > > So I think it is only partially true to say that when commute > functions are rerun during a commit, they use the most recently > committed values of Refs. That only happens if ref-set and alter were > not used on the Ref before the call to commute. > > Am I understanding this correctly? >
Not really. If this transaction is succeeding, and it has written to a ref prior to its commute, then those writes *are* the most recently committed value, committed now as a prior part of the same transaction. Rich --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
