mirror of
https://github.com/neondatabase/neon.git
synced 2026-05-15 12:10:37 +00:00
c14cf15b52
I believe the explicit memory fence instructions are unnecessary. Performing a store with Release ordering makes all the previous non-atomic writes visible too. Per rust docs for Ordering::Release ( https://doc.rust-lang.org/std/sync/atomic/enum.Ordering.html#variant.Release): > When coupled with a store, all previous operations become ordered > before any load of this value with Acquire (or stronger) > ordering. In particular, all previous writes become visible to all > threads that perform an Acquire (or stronger) load of this value. > > ... > > Corresponds to memory_order_release in C++20. The "all previous writes" means non-atomic writes too. It's not very clear from that text, but the C++20 docs that it links to is more explicit about it: > All memory writes (including non-atomic and relaxed atomic) that > happened-before the atomic store from the point of view of thread A, > become visible side-effects in thread B. That is, once the atomic > load is completed, thread B is guaranteed to see everything thread A > wrote to memory. In addition to removing the fence instructions, fix the comments on each atomic Acquire operation to point to the correct Release counterpart. We had such comments but they had gone out-of-date as code has moved.