https://jasper-aa64.github.io/tags/spsc/Recent content in Spsc on JasperHugoen-usSun, 20 Sep 2026 00:00:00 +0000https://jasper-aa64.github.io/posts/lock-free-queue-logger-micro-batching/Sun, 20 Sep 2026 00:00:00 +0000https://jasper-aa64.github.io/posts/lock-free-queue-logger-micro-batching/A lock-free SPSC queue works because every shared variable has exactly one writer: each side updates only its own counter and merely reads the other’s. The rest is keeping that property from being quietly undone — a shared element count both cores fight over (subtract two counters instead), a full-check that reads the other core on every call (cache the other side’s cursor, which can only be wrong in the safe direction), a mirrored mapping that removes the wrap-around seam, and a logger that pushes one character per slot (thirty slots for one log line, five as text runs). It ends with the vocabulary that keeps lock-free claims honest: SPSC is wait-free only through a fail-fast interface, finite steps are not finite time, and a bounded queue must always choose between dropping and blocking.