Hi Stu, The point is that there's no reason for the READ transaction to restart, it has only made reads of refs and those reads should be consistent with each other from the snapshot of the the ref world as per...
In practice, this means: 1. All reads of Refs will see a consistent snapshot of the 'Ref world' as of the starting point of the transaction (its 'read point'). The transaction *will*see any changes it has made. This is called the * in-transaction-value* * * from: http://clojure.org/refs The fact that the behaviour changes in the presence of history is a problem in my opinion. Yes you can 'ensure' that the refs aren't modified, but that means writes are blocked by reads - is that desired? Neale {t: @sw1nn <https://twitter.com/#!/sw1nn>, w: sw1nn.com } On Tue, Apr 17, 2012 at 2:59 AM, Stuart Halloway <stuart.hallo...@gmail.com>wrote: > Hi, > > [disclojure]: I've asked about this on SO, but figured out what was > happening myself[1] and that led to this enquiry. > > > It seems that the consistency of refs within an STM transaction (dosync) > depends on whether the ref has history. > > So if you create 2 refs and then read them in a transaction they could be > inconsistent with each other. i.e they won't necessarily return the value > the ref had at the start of the transaction. > > > However, if you give the refs some history by updating them in a prior > transaction, then the two refs will be consistent with each other in > subsequent transactions. > > This seems rather dangerous to me. Is there a rational for not creating at > least 1 history entry for a ref at ref creation time. > > Neale > {t: @sw1nn <https://twitter.com/#!/sw1nn>, w: sw1nn.com } > > > [1] > http://stackoverflow.com/questions/10178639/are-refs-really-consistent-within-a-stm-transaction > > > Hi Neale, > > Your example does not appear to match your conclusion. It shows that a > transaction restarts, and that the reads are all consistent as of the > restarted transaction. > > Cheers, > Stu > > > Stuart Halloway > Clojure/core > http://clojure.com > > > -- > 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 -- 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
