On 10 December 2015 at 20:20, Julian Foad <julianf...@apache.org> wrote: > Ivan Zhakov wrote: >> On 10 December 2015 at 19:14, Julian Foad <julianf...@apache.org> wrote: >>> APR devs, Subversion devs: >>> >>> On Subversion's Mac OS buildbots it appears that apr_hash_overlay() >>> sometimes returns a hash containing duplicate keys, which (as I >>> understand it) should be impossible. >>> >>> We had an issue where some 'svnmover' tests were failing only on Mac >>> OS buildbots. I added some debugging in Subversion commits r1719056, >>> r1719067, r1719072, r1719074. >>> >>> Buildbot result: >>> >>> https://ci.apache.org/builders/svn-x64-macosx-bdb/builds/485/steps/Test%20ra_svn%2Bbdb >>> --> debug output in 'faillog' shows duplicate keys in hash: >>> "union_children={A, iota, foo, boozle, boozle, iota}" >>> >>> I replaced apr_hash_overlay() with my own simple re-implementation: >>> >>> http://svn.apache.org/r1719089 -- re-implement hash overlay >>> >> Hi Julian, >> >> That could be possible if two hashes uses different hash functions. >> This could happen if you're using svn_hash__make() directly or >> indirectly: for example RA get_dirent for svn:// protocol returns hash >> with non-standard hash-function. > > Ugh. Yes, that is probably the cause. Thanks. > > I can see now that the doc string of apr_hash_overlay() does say "Both > hash tables must use the same hash function" but that was not obvious, > and I had totally forgotten that our Subversion code was using more > than one hash function. > > I will use my own hash overlay function from now on. > I don't think this is proper fix for this problem. I think returning hash with non-standard hash function from public API is a bug (and API regression). Other API users may get to the same situation. So proper fix would be revert these optimizations from public API imo.
-- Ivan Zhakov