Function sendChildInfoGeneric

src/childinfo.cpp:71–113

Send save data to parent. */

/* Send save data to parent. */
void sendChildInfoGeneric(childInfoType info_type, size_t keys, double progress, const char *pname) {
    if (g_pserver->child_info_pipe[1] == -1) return;
    if (g_pserver->rdbThreadVars.fRdbThreadActive && g_pserver->rdbThreadVars.fRdbThreadCancel) return;

    static monotime cow_updated = 0;
    static uint64_t cow_update_cost = 0;
    static size_t cow = 0;

    child_info_data data = {0}; /* zero everything, including padding to satisfy valgrind */

    /* When called to report current info, we need to throttle down CoW updates as they
     * can be very expensive. To do that, we measure the time it takes to get a reading
     * and schedule the next reading to happen not before time*CHILD_COW_COST_FACTOR
     * passes. */

    monotime now = getMonotonicUs();
    if (info_type != CHILD_INFO_TYPE_CURRENT_INFO ||
        !cow_updated ||
        now - cow_updated > cow_update_cost * CHILD_COW_DUTY_CYCLE)
    {
        cow = zmalloc_get_private_dirty(-1);
        cow_updated = getMonotonicUs();
        cow_update_cost = cow_updated - now;

        if (cow) {
            serverLog((info_type == CHILD_INFO_TYPE_CURRENT_INFO) ? LL_VERBOSE : LL_NOTICE,
                      "%s: %zu MB of memory used by copy-on-write",
                      pname, cow / (1024 * 1024));
        }
    }

    data.information_type = info_type;
    data.keys = keys;
    data.cow = cow;
    data.cow_updated = cow_updated;
    data.progress = progress;

    ssize_t wlen = sizeof(data);

    if (write(g_pserver->child_info_pipe[1], &data, wlen) != wlen) {
        /* Nothing to do on error, this will be detected by the other side. */
    }
}

/* Update Child info. */
void updateChildInfo(childInfoType information_type, size_t cow, monotime cow_updated, size_t keys, double progress) {