Chapter 09 — SPSC Ring Buffer
A single-producer/single-consumer ring buffer is safe without a lock because each counter has exactly one writer.
The full source for this example lives in
examples/concurrency/09-lock-free-data-structures/— clone the repo,cdin, and./demo.sh.
Chapter reference: Doc 9 — Lock-Free Data Structures
What it shows
One producer pushes values into a bounded ring and one consumer pops them, with tail written only by the producer and head written only by the consumer — the single-writer-per-counter property that lets the ring run with no lock at all. Correctness is checked per logical position, not just by a summed total, across both padding settings and capacities down to one slot, the chapter’s maximum-contention case; a lost or duplicated item is caught immediately rather than possibly canceling out in an aggregate sum. A soft timing check reports that padding head and tail onto separate cache lines should raise throughput, since an unpadded layout has the consumer’s write to head invalidate the producer’s cached tail even though the producer never touches head.
Running it
cd examples/concurrency/09-lock-free-data-structures
./demo.sh # build + run spsc_ring (correctness sweep + timing) + verify.lua
./demo.sh --clean # remove the image