SGTM On Thu, Jul 5, 2018 at 6:13 PM, Tim Armstrong < [email protected]> wrote:
> Sounds like unique_ptr is preferred then going forward. I updated the wiki > page. > > > Fwiw, I was under the impression from talking with people in the past > that > > we were already trying to make this move, and the > > PartitionedAggregationNode refactor that just went in made the switch to > > unique_ptr, though no one commented on it in the review. > Yeah it sounds like there are two camps - people wanting to use unique_ptr > and people who don't mind scoped_ptr but are apathetic about it. > > > I suspect we could also make own own immobile_ptr with minimal effort, > > thereby both making the difference more visible and reducing boost > > dependence. > I'd thought about this too and I'm not sure that it's worth doing something > non-standard that new contributors will have to learn. > > > On Thu, Jul 5, 2018 at 5:27 PM, Todd Lipcon <[email protected]> > wrote: > > > Definitely in favor. > > > > Personally I never found the "this pointer isn't movable" to be a > > worthwhile distinction. With unique_ptr you need to pretty explicitly > move > > it using std::move, so you don't get "accidental" moves like you used to > > with std::auto_ptr. > > > > Looking briefly at Kudu we have 129 unique_ptr members and only 7 of them > > are marked const, so at least we haven't found that a particularly useful > > pattern. > > > > -Todd > > > > On Thu, Jul 5, 2018 at 5:23 PM, Jim Apple <[email protected]> > > wrote: > > > > > I suspect we could also make own own immobile_ptr with minimal effort, > > > thereby both making the difference more visible and reducing boost > > > dependence. > > > > > > On Thu, Jul 5, 2018 at 5:17 PM, Sailesh Mukil > > <[email protected] > > > > > > > wrote: > > > > > > > I'm in favor. > > > > > > > > Since the main distinction is that a unique_ptr is moveable, whereas > a > > > > scoped_ptr is not, we should just make sure that we do our due > > diligence > > > > during code reviews so that we catch those cases. > > > > > > > > Also, making a unique_ptr const disallows moving it, since the move > > > > constructor takes a non-const unique_ptr container. It probably won't > > > work > > > > in all places, but we could enforce that in certain parts of the > code. > > > > > > > > On Thu, Jul 5, 2018 at 4:49 PM, Thomas Tauber-Marshall < > > > > [email protected]> wrote: > > > > > > > > > I'm definitely in favor of using more standard c++ to reduce both > > > > confusion > > > > > and our reliance on boost, especially as I suspect a lot of people > > (eg. > > > > me) > > > > > don't know the subtle difference between scoped_ptr and unique_ptr > > off > > > > the > > > > > top of their head anyways. > > > > > > > > > > Fwiw, I was under the impression from talking with people in the > past > > > > that > > > > > we were already trying to make this move, and the > > > > > PartitionedAggregationNode refactor that just went in made the > switch > > > to > > > > > unique_ptr, though no one commented on it in the review. > > > > > > > > > > On Thu, Jul 5, 2018 at 4:39 PM Tim Armstrong > > > > > <[email protected]> wrote: > > > > > > > > > > > I was just talking with Michael Ho on a review about this > > > > > > https://gerrit.cloudera.org/#/c/10810/7/be/src/exec/scan- > > node.h@271 > > > > > > > > > > > > For a while we've continued using scoped_ptr in some places > because > > > it > > > > > > supports a smaller set of operators and implies that the pointer > > > isn't > > > > > > movable. See > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/IMPALA/ > > > > > Resource+Management+Best+Practices+in+Impala > > > > > > . > > > > > > > > > > > > I don't think we're consistently following this pattern and it > > seems > > > to > > > > > > cause some confusion about what the best practice is, > particularly > > > for > > > > > > people coming from other code bases. I personally like the > > > distinction, > > > > > but > > > > > > I don't feel that strongly about it. > > > > > > > > > > > > What do people think? Should we continue using scoped_ptr or move > > > away > > > > > from > > > > > > it. There is already a JIRA to make the change but we haven't > done > > it > > > > > > because of the above reasons: > > > > > > https://issues.apache.org/jira/browse/IMPALA-3444 > > > > > > > > > > > > - Tim > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > Todd Lipcon > > Software Engineer, Cloudera > > >
