Function srandmemberWithCountCommand

src/t_set.cpp:664–819

#define SRANDMEMBER_SUB_STRATEGY_MUL 3

void srandmemberWithCountCommand(client *c) {
    long l;
    unsigned long count, size;
    int uniq = 1;
    robj_roptr set;
    const char *ele;
    int64_t llele = 0;
    int encoding;

    dict *d;

    if (getRangeLongFromObjectOrReply(c,c->argv[2],-LONG_MAX,LONG_MAX,&l,NULL) != C_OK) return;
    if (l < -g_pserver->rand_total_threshold || l > g_pserver->rand_total_threshold) {
        addReplyError(c,"value is out of range");
        return;
    }
    if (l >= 0) {
        count = (unsigned long) l;
    } else {
        /* A negative count means: return the same elements multiple times
         * (i.e. don't remove the extracted element after every extraction). */
        count = -l;
        uniq = 0;
    }

    if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.emptyarray))
        == nullptr || checkType(c,set,OBJ_SET)) return;
    size = setTypeSize(set);

    /* If count is zero, serve it ASAP to avoid special cases later. */
    if (count == 0) {
        addReply(c,shared.emptyarray);
        return;
    }

    /* CASE 1: The count was negative, so the extraction method is just:
     * "return N random elements" sampling the whole set every time.
     * This case is trivial and can be served without auxiliary data
     * structures. This case is the only one that also needs to return the
     * elements in random order. */
    if (!uniq || count == 1) {
        addReplyArrayLen(c,count);
        while(count--) {
            encoding = setTypeRandomElement(set,&ele,&llele);
            if (encoding == OBJ_ENCODING_INTSET) {
                addReplyBulkLongLong(c,llele);
            } else {
                addReplyBulkCBuffer(c,ele,sdslen(ele));
            }
            if (c->flags & CLIENT_CLOSE_ASAP)
                break;
        }
        return;
    }

    /* CASE 2:
     * The number of requested elements is greater than the number of
     * elements inside the set: simply return the whole set. */