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stack.h  view on Meta::CPAN

 * rather than resurrecting a phantom FILLED slot. The pusher's value is
 * dropped — equivalent to a crashed pusher. In practice the gap between
 * claim_write and publish is sub-microsecond memcpy time, so the false-
 * positive threshold is many orders of magnitude away from normal latency. */
static inline uint32_t stk_drain(StkHandle *h) {
    StkHeader *hdr = h->hdr;
    uint32_t t = __atomic_exchange_n(&hdr->top, 0, __ATOMIC_ACQ_REL);
    if (t == 0) return 0;
    /* Wall-clock deadline for the per-slot wait. We hot-spin first, then
     * fall back to short sleeps to avoid burning a core for 2s on a stuck
     * slot. The deadline is checked periodically (every 64 iterations) to
     * keep the steady-state cost ~zero. */
    for (uint32_t i = 0; i < t; i++) {
        struct timespec dl;
        int dl_set = 0;
        uint32_t spins = 0;
        for (;;) {
            uint64_t c = __atomic_load_n(&h->ctl[i], __ATOMIC_ACQUIRE);
            uint32_t st = STK_SLOT_STATE(c);
            if (st == STK_SLOT_FILLED) {
                uint64_t nc = (STK_SLOT_GEN(c) << 2) | STK_SLOT_READING;