On Wed, Aug 30, 2017 at 06:59:22PM +0000, Jeff Hostetler wrote: > From: Jeff Hostetler <jeffh...@microsoft.com> > > This is to address concerns raised by ThreadSanitizer on the > mailing list about threaded unprotected R/W access to map.size with my > previous > "disallow rehash" change (0607e10009ee4e37cb49b4cec8d28a9dda1656a4). See: > https://public-inbox.org/git/adb37b70139fd1e2bac18bfd22c8b96683ae18eb.1502780344.git.martin.ag...@gmail.com/ > > Add API to hashmap to disable item counting and to disable automatic > rehashing. > Also include APIs to re-enable item counting and automatica rehashing.
It may be worth summarizing the discussion at that thread here. At first glance, it looks like this is woefully inadequate for allowing multi-threaded access. But after digging, the issue is that we're really trying to accommodate one specific callers which is doing its own per-bucket locking, and which needs the internals of the hashmap to be truly read-only. I suspect the code might be easier to follow if that pattern were pushed into its own threaded_hashmap that disabled the size and handled the mod-n locking, but I don't insist on that as a blocker to this fix. -Peff
