Function spopWithCountCommand

app/redis-6.2.6/src/t_set.c:457–598

#define SPOP_MOVE_STRATEGY_MUL 5

void spopWithCountCommand(client *c) {
    long l;
    unsigned long count, size;
    robj *set;

    /* Get the count argument */
    if (getPositiveLongFromObjectOrReply(c,c->argv[2],&l,NULL) != C_OK) return;
    count = (unsigned long) l;

    /* Make sure a key with the name inputted exists, and that it's type is
     * indeed a set. Otherwise, return nil */
    if ((set = lookupKeyWriteOrReply(c,c->argv[1],shared.emptyset[c->resp]))
        == NULL || checkType(c,set,OBJ_SET)) return;

    /* If count is zero, serve an empty set ASAP to avoid special
     * cases later. */
    if (count == 0) {
        addReply(c,shared.emptyset[c->resp]);
        return;
    }

    size = setTypeSize(set);

    /* Generate an SPOP keyspace notification */
    notifyKeyspaceEvent(NOTIFY_SET,"spop",c->argv[1],c->db->id);
    server.dirty += (count >= size) ? size : count;

    /* CASE 1:
     * The number of requested elements is greater than or equal to
     * the number of elements inside the set: simply return the whole set. */
    if (count >= size) {
        /* We just return the entire set */
        sunionDiffGenericCommand(c,c->argv+1,1,NULL,SET_OP_UNION);

        /* Delete the set as it is now empty */
        dbDelete(c->db,c->argv[1]);
        notifyKeyspaceEvent(NOTIFY_GENERIC,"del",c->argv[1],c->db->id);

        /* Propagate this command as a DEL operation */
        rewriteClientCommandVector(c,2,shared.del,c->argv[1]);
        signalModifiedKey(c,c->db,c->argv[1]);
        return;
    }

    /* Case 2 and 3 require to replicate SPOP as a set of SREM commands.
     * Prepare our replication argument vector. Also send the array length
     * which is common to both the code paths. */
    robj *propargv[3];
    propargv[0] = shared.srem;
    propargv[1] = c->argv[1];
    addReplySetLen(c,count);

    /* Common iteration vars. */
    sds sdsele;
    robj *objele;
    int encoding;
    int64_t llele;
    unsigned long remaining = size-count; /* Elements left after SPOP. */