Function cbm_scale_end

src/foundation/profile.c:133–186

}

void cbm_scale_end(cbm_scale_probe_t *probe) {
    if (!probe || probe->total < SCALE_MIN_ITEMS) {
        return;
    }
    int recorded = atomic_load_explicit(&probe->next_cp, memory_order_relaxed);
    if (recorded < 2) {
        return; /* need two points to speak about growth at all */
    }
    long first_us = probe->cp_us[0];
    long first_n = probe->cp_items[0];
    long last_us = probe->cp_us[recorded - 1];
    long last_n = probe->cp_items[recorded - 1];
    if (first_us < SCALE_MIN_FIRST_US || first_n <= 0 || last_n <= first_n || last_us <= 0) {
        return;
    }

    double k = cbm_scale_fit_k(first_n, first_us, last_n, last_us);
    if (k < 0.0) {
        return;
    }
    long us_per_item = last_us / last_n;

    char k_buf[PROF_BUF_LEN];
    char n_buf[PROF_BUF_LEN];
    char per_buf[PROF_BUF_LEN];
    char ms_buf[PROF_BUF_LEN];
    snprintf(k_buf, sizeof(k_buf), "%.2f", k);
    snprintf(n_buf, sizeof(n_buf), "%ld", last_n);
    snprintf(per_buf, sizeof(per_buf), "%ld", us_per_item);
    snprintf(ms_buf, sizeof(ms_buf), "%ld", last_us / PROF_US_PER_MS);

    if (k >= CBM_SCALE_WARN_K) {
        /* Unflagged on purpose: this is the alarm the next accidental O(n^2)
         * should trip in an ordinary user's log. */
        cbm_log_warn("scaling.superlinear", "phase", probe->phase, "k", k_buf, "items", n_buf,
                     "elapsed_ms", ms_buf, "us_per_item", per_buf);
    }
    if (!cbm_profile_active) {
        return;
    }
    char curve[PROF_BUF_LEN * CBM_SCALE_CHECKPOINTS];
    int used = 0;
    for (int i = 0; i < recorded && used < (int)sizeof(curve) - 1; i++) {
        int wrote =
            snprintf(curve + used, sizeof(curve) - (size_t)used, "%s%ld:%ld", i == 0 ? "" : ",",
                     probe->cp_items[i], probe->cp_us[i] / PROF_US_PER_MS);
        if (wrote < 0) {
            break;
        }
        used += wrote;
    }
    cbm_log_info("scaling", "phase", probe->phase, "k", k_buf, "items", n_buf, "elapsed_ms", ms_buf,
                 "us_per_item", per_buf, "curve_items_ms", curve);
}