Function processEventsWhileBlocked

src/networking.cpp:4060–4104

This function is called by Redis in order to process a few events from * time to time while blocked into some not interruptible operation. * This allows to reply to clients with the -LOADING error while loading the * data set at startup or after a full resynchronization with the master * and so forth. * * It calls the event loop in order to process a few events. Specifically we * try to cal

 *
 * The function returns the total number of events processed. */
void processEventsWhileBlocked(int iel) {

    int eventsCount = 0;
    executeWithoutGlobalLock([&](){
        int iterations = 4; /* See the function top-comment. */
        try
        {
            ProcessingEventsWhileBlocked = 1;
            while (iterations--) {
                long long startval = g_pserver->events_processed_while_blocked;
                long long ae_events = aeProcessEvents(g_pserver->rgthreadvar[iel].el,
                    AE_FILE_EVENTS|AE_DONT_WAIT|
                    AE_CALL_BEFORE_SLEEP|AE_CALL_AFTER_SLEEP);
                /* Note that g_pserver->events_processed_while_blocked will also get
                * incremeted by callbacks called by the event loop handlers. */
                eventsCount += ae_events;
                long long events = eventsCount - startval;
                if (!events) break;
            }
            ProcessingEventsWhileBlocked = 0;
        }
        catch (...)
        {
            ProcessingEventsWhileBlocked = 0;
            throw;
        }
    });

    // Try to complete any async rehashes (this would normally happen in dbCron, but that won't run here)
    for (int idb = 0; idb < cserver.dbnum; ++idb) {
        redisDb *db = g_pserver->db[idb];
        while (db->dictUnsafeKeyOnly()->asyncdata != nullptr) {
            if (!db->dictUnsafeKeyOnly()->asyncdata->done)
                break;
            dictCompleteRehashAsync(db->dictUnsafeKeyOnly()->asyncdata, false /*fFree*/);
        }
    }
    g_pserver->events_processed_while_blocked += eventsCount;

    whileBlockedCron();

    // If a different thread processed the shutdown we need to abort the lua command or we will hang
    if (serverTL->el->stop)
        throw ShutdownException();
}