Function computeDatasetDigest

app/redis-6.2.6/src/debug.c:273–313

Compute the dataset digest. Since keys, sets elements, hashes elements * are not ordered, we use a trick: every aggregate digest is the xor * of the digests of their elements. This way the order will not change * the result. For list instead we use a feedback entering the output digest * as input in order to ensure that a different ordered list will result in * a different digest. */

 * as input in order to ensure that a different ordered list will result in
 * a different digest. */
void computeDatasetDigest(unsigned char *final) {
    unsigned char digest[20];
    dictIterator *di = NULL;
    dictEntry *de;
    int j;
    uint32_t aux;

    memset(final,0,20); /* Start with a clean result */

    for (j = 0; j < server.dbnum; j++) {
        redisDb *db = server.db+j;

        if (dictSize(db->dict) == 0) continue;
        di = dictGetSafeIterator(db->dict);

        /* hash the DB id, so the same dataset moved in a different
         * DB will lead to a different digest */
        aux = htonl(j);
        mixDigest(final,&aux,sizeof(aux));

        /* Iterate this DB writing every entry */
        while((de = dictNext(di)) != NULL) {
            sds key;
            robj *keyobj, *o;

            memset(digest,0,20); /* This key-val digest */
            key = dictGetKey(de);
            keyobj = createStringObject(key,sdslen(key));

            mixDigest(digest,key,sdslen(key));

            o = dictGetVal(de);
            xorObjectDigest(db,keyobj,digest,o);

            /* We can finally xor the key-val digest to the final digest */
            xorDigest(final,digest,20);
            decrRefCount(keyobj);
        }
        dictReleaseIterator(di);
    }
}

#ifdef USE_JEMALLOC
void mallctl_int(client *c, robj **argv, int argc) {