On Fri, Jun 19, 2009 at 9:35 AM, Eric Willigers<[email protected]> wrote: > > On Jun 18, 9:35 pm, Rich Hickey <[email protected]> wrote: >> http://clojure.org/refs >> >> point #8: >> >> "If a constraint on the validity of a value of a Ref that is being >> changed depends upon the simultaneous value of a Ref that is not being >> changed, that second Ref can be protected from modification by calling >> ensure. Refs 'ensured' this way will be protected (item #3), but don't >> change the world (item #2)." >> >> That describes your situation, and you can use 'ensure' to ensure the >> serializability of your reads. > > Thanks, that was all very helpful. With ensure, there's no write skew. > > >> This is better than the "dummy write" >> solution in that multiple ensures of the same refs don't conflict. > > I haven't been able to verify this part - are you refering to > Clojure's current implementation? In my experiment below using Clojure > 1.0.0, I'm seeing conflicts. >
They don't conflict, but you are correct that Clojure's STM currently doesn't leverage that fact. It is my intention that at some point it will, so please use ensure rather than dummy writes. Rich --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to [email protected] Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
