void sinterGenericCommand(client *c, robj **setkeys,
                          unsigned long setnum, robj *dstkey) {
    robj **sets = zmalloc(sizeof(robj*)*setnum);
    setTypeIterator *si;
    robj *dstset = NULL;
    sds elesds;
    int64_t intobj;
    void *replylen = NULL;
    unsigned long j, cardinality = 0;
    int encoding, empty = 0;

    for (j = 0; j < setnum; j++) {
        robj *setobj = dstkey ?
            lookupKeyWrite(c->db,setkeys[j]) :
            lookupKeyRead(c->db,setkeys[j]);
        if (!setobj) {
            /* A NULL is considered an empty set */
            empty += 1;
            sets[j] = NULL;
            continue;
        }
        if (checkType(c,setobj,OBJ_SET)) {
            zfree(sets);
            return;
        }
        sets[j] = setobj;
    }

    /* Set intersection with an empty set always results in an empty set.
     * Return ASAP if there is an empty set. */
    if (empty > 0) {
        zfree(sets);
        if (dstkey) {
            if (dbDelete(c->db,dstkey)) {
                signalModifiedKey(c,c->db,dstkey);
                notifyKeyspaceEvent(NOTIFY_GENERIC,"del",dstkey,c->db->id);
                server.dirty++;
            }
            addReply(c,shared.czero);
        } else {
            addReply(c,shared.emptyset[c->resp]);
        }
        return;
    }

    /* Sort sets from the smallest to largest, this will improve our
     * algorithm's performance */
    qsort(sets,setnum,sizeof(robj*),qsortCompareSetsByCardinality);

    /* The first thing we should output is the total number of elements...
     * since this is a multi-bulk write, but at this stage we don't know
     * the intersection set size, so we use a trick, append an empty object
     * to the output list and save the pointer to later modify it with the
     * right length */
    if (!dstkey) {
        replylen = addReplyDeferredLen(c);
    } else {
        /* If we have a target key where to store the resulting set
         * create this key with an empty set inside */
        dstset = createIntsetObject();
    }

    /* Iterate all the elements of the first (smallest) set, and test
     * the element against all the other sets, if at least one set does
     * not include the element it is discarded */
    si = setTypeInitIterator(sets[0]);
    while((encoding = setTypeNext(si,&elesds,&intobj)) != -1) {
        for (j = 1; j < setnum; j++) {
            if (sets[j] == sets[0]) continue;
            if (encoding == OBJ_ENCODING_INTSET) {
                /* intset with intset is simple... and fast */
                if (sets[j]->encoding == OBJ_ENCODING_INTSET &&
                    !intsetFind((intset*)sets[j]->ptr,intobj))
                {
                    break;
                /* in order to compare an integer with an object we
                 * have to use the generic function, creating an object
                 * for this */
                } else if (sets[j]->encoding == OBJ_ENCODING_HT) {
                    elesds = sdsfromlonglong(intobj);
                    if (!setTypeIsMember(sets[j],elesds)) {
                        sdsfree(elesds);
                        break;
                    }
                    sdsfree(elesds);
                }
            } else if (encoding == OBJ_ENCODING_HT) {
                if (!setTypeIsMember(sets[j],elesds)) {
                    break;
                }
            }
        }

        /* Only take action when all sets contain the member */
        if (j == setnum) {
            if (!dstkey) {
                if (encoding == OBJ_ENCODING_HT)
                    addReplyBulkCBuffer(c,elesds,sdslen(elesds));
                else
                    addReplyBulkLongLong(c,intobj);
                cardinality++;
            } else {
                if (encoding == OBJ_ENCODING_INTSET) {
                    elesds = sdsfromlonglong(intobj);
                    setTypeAdd(dstset,elesds);
                    sdsfree(elesds);
                } else {
                    setTypeAdd(dstset,elesds);
                }
            }
        }
    }
    setTypeReleaseIterator(si);

    if (dstkey) {
        /* Store the resulting set into the target, if the intersection
         * is not an empty set. */
        int deleted = dbDelete(c->db,dstkey);
        if (setTypeSize(dstset) > 0) {
            dbAdd(c->db,dstkey,dstset);
            addReplyLongLong(c,setTypeSize(dstset));
            notifyKeyspaceEvent(NOTIFY_SET,"sinterstore",
                dstkey,c->db->id);
        } else {
            decrRefCount(dstset);
            addReply(c,shared.czero);
            if (deleted)
                notifyKeyspaceEvent(NOTIFY_GENERIC,"del",
                    dstkey,c->db->id);
        }
        signalModifiedKey(c,c->db,dstkey);
        server.dirty++;
    } else {
        setDeferredSetLen(c,replylen,cardinality);
    }
    zfree(sets);
}
void sinterGenericCommand(client *c, robj **setkeys,
                          unsigned long setnum, robj *dstkey) {
    robj **sets = zmalloc(sizeof(robj*)*setnum);
    setTypeIterator *si;
    robj *dstset = NULL;
    sds elesds;
    int64_t intobj;
    void *replylen = NULL;
    unsigned long j, cardinality = 0;
    int encoding, empty = 0;

    for (j = 0; j < setnum; j++) {
        robj *setobj = dstkey ?
            lookupKeyWrite(c->db,setkeys[j]) :
            lookupKeyRead(c->db,setkeys[j]);
        if (!setobj) {
             
            empty += 1;
            sets[j] = NULL;
            continue;
        }
        if (checkType(c,setobj,OBJ_SET)) {
            zfree(sets);
            return;
        }
        sets[j] = setobj;
    }

     
    if (empty > 0) {
        zfree(sets);
        if (dstkey) {
            if (dbDelete(c->db,dstkey)) {
                signalModifiedKey(c,c->db,dstkey);
                notifyKeyspaceEvent(NOTIFY_GENERIC,"del",dstkey,c->db->id);
                server.dirty++;
            }
            addReply(c,shared.czero);
        } else {
            addReply(c,shared.emptyset[c->resp]);
        }
        return;
    }

     
    qsort(sets,setnum,sizeof(robj*),qsortCompareSetsByCardinality);

     
    if (!dstkey) {
        replylen = addReplyDeferredLen(c);
    } else {
         
        dstset = createIntsetObject();
    }

     
    si = setTypeInitIterator(sets[0]);
    while((encoding = setTypeNext(si,&elesds,&intobj)) != -1) {
        for (j = 1; j < setnum; j++) {
            if (sets[j] == sets[0]) continue;
            if (encoding == OBJ_ENCODING_INTSET) {
                 
                if (sets[j]->encoding == OBJ_ENCODING_INTSET &&
                    !intsetFind((intset*)sets[j]->ptr,intobj))
                {
                    break;
                 
                } else if (sets[j]->encoding == OBJ_ENCODING_HT) {
                    elesds = sdsfromlonglong(intobj);
                    if (!setTypeIsMember(sets[j],elesds)) {
                        sdsfree(elesds);
                        break;
                    }
                    sdsfree(elesds);
                }
            } else if (encoding == OBJ_ENCODING_HT) {
                if (!setTypeIsMember(sets[j],elesds)) {
                    break;
                }
            }
        }

         
        if (j == setnum) {
            if (!dstkey) {
                if (encoding == OBJ_ENCODING_HT)
                    addReplyBulkCBuffer(c,elesds,sdslen(elesds));
                else
                    addReplyBulkLongLong(c,intobj);
                cardinality++;
            } else {
                if (encoding == OBJ_ENCODING_INTSET) {
                    elesds = sdsfromlonglong(intobj);
                    setTypeAdd(dstset,elesds);
                    sdsfree(elesds);
                } else {
                    setTypeAdd(dstset,elesds);
                }
            }
        }
    }
    setTypeReleaseIterator(si);

    if (dstkey) {
         
        int deleted = dbDelete(c->db,dstkey);
        if (setTypeSize(dstset) > 0) {
            dbAdd(c->db,dstkey,dstset);
            addReplyLongLong(c,setTypeSize(dstset));
            notifyKeyspaceEvent(NOTIFY_SET,"sinterstore",
                dstkey,c->db->id);
        } else {
            decrRefCount(dstset);
            addReply(c,shared.czero);
            if (deleted)
                notifyKeyspaceEvent(NOTIFY_GENERIC,"del",
                    dstkey,c->db->id);
        }
        signalModifiedKey(c,c->db,dstkey);
        server.dirty++;
    } else {
        setDeferredSetLen(c,replylen,cardinality);
    }
    zfree(sets);
}