On 06.02.23 23:29, Klaus Schmidinger wrote:
It is supposed to be shared by *exactly* two threads. One only writing 'head', the other only writing 'tail'.
Two-ended buffers are pretty good when used correctly, but nowadays they have a small chance of triggering memory ordering issues, where it is possible that written data to the buffer is still stuck in a distant cache, while the updated head pointer is already known to other CPU cores. To be absolutely safe, the head pointer would need atomic read/write, forcing ordering with a memory barrier.
But in general the timing for such a bug is pretty narrow, and advanced CPUs (esp. intel/amd) make sure that things get stored in order anyway. Worst thing would also just be false data read, not a crash.
Cheers,
Udo