Redis 中的 KEYS 命令

// https://github.com/redis/redis/blob/ae6a2aa95cd094b032e7a69b8b59f64dd1ed085f/src/db.c#L785
void keysCommand(client *c) {
    dictIterator *di;
    dictEntry *de;
    sds pattern = c->argv[1]->ptr;
    int plen = sdslen(pattern), allkeys;
    unsigned long numkeys = 0;
    void *replylen = addReplyDeferredLen(c);


    di = dictGetSafeIterator(c->db->dict);
    allkeys = (pattern[0] == '*' && plen == 1);
    robj keyobj;
    while((de = dictNext(di)) != NULL) {
        sds key = dictGetKey(de);


        if (allkeys || stringmatchlen(pattern,plen,key,sdslen(key),0)) {
            initStaticStringObject(keyobj, key);
            if (!keyIsExpired(c->db, &keyobj)) {
                addReplyBulkCBuffer(c, key, sdslen(key));
                numkeys++;
            }
        }
        if (c->flags & CLIENT_CLOSE_ASAP)
            break;
    }
    dictReleaseIterator(di);
    setDeferredArrayLen(c,replylen,numkeys);
}

dictIterator *dictGetSafeIterator(dict *d) {
    dictIterator *i = dictGetIterator(d);

    i->safe = 1;
    return i;
}

dictEntry *dictNext(dictIterator *iter)
{
    while (1) {
        if (iter->entry == NULL) {
            if (iter->index == -1 && iter->table == 0) {
                if (iter->safe)
                    dictPauseRehashing(iter->d);
                else
                    iter->fingerprint = dictFingerprint(iter->d);
            }
            iter->index++;
            if (iter->index >= (long) DICTHT_SIZE(iter->d->ht_size_exp[iter->table])) {
                if (dictIsRehashing(iter->d) && iter->table == 0) {
                    iter->table++;
                    iter->index = 0;
                } else {
                    break;
                }
            }
            iter->entry = iter->d->ht_table[iter->table][iter->index];
        } else {
            iter->entry = iter->nextEntry;
        }
        if (iter->entry) {
            /* We need to save the 'next' here, the iterator user
             * may delete the entry we are returning. */
            iter->nextEntry = dictGetNext(iter->entry);
            return iter->entry;
        }
    }
    return NULL;
}

dictEntry *dictFind(dict *d, const void *key)
{
    dictEntry *he;
    uint64_t h, idx, table;

    if (dictSize(d) == 0) return NULL; /* dict is empty */
    if (dictIsRehashing(d)) _dictRehashStep(d);
    h = dictHashKey(d, key);
    for (table = 0; table <= 1; table++) {
        idx = h & DICTHT_SIZE_MASK(d->ht_size_exp[table]);
        he = d->ht_table[table][idx];
        while(he) {
            void *he_key = dictGetKey(he);
            if (key == he_key || dictCompareKeys(d, key, he_key))
                return he;
            he = dictGetNext(he);
        }
        if (!dictIsRehashing(d)) return NULL;
    }
    return NULL;
}

/* This function performs just a step of rehashing, and only if hashing has
 * not been paused for our hash table. When we have iterators in the
 * middle of a rehashing we can't mess with the two hash tables otherwise
 * some elements can be missed or duplicated.
 *
 * This function is called by common lookup or update operations in the
 * dictionary so that the hash table automatically migrates from H1 to H2
 * while it is actively used. */
static void _dictRehashStep(dict *d) {
    if (d->pauserehash == 0) dictRehash(d,1);
}

long long getExpire(redisDb *db, robj *key) {
    dictEntry *de;

    /* No expire? return ASAP */
    if (dictSize(db->expires) == 0 ||
       (de = dictFind(db->expires,key->ptr)) == NULL) return -1;

    return dictGetSignedIntegerVal(de);
}

/* Check if the key is expired. */
int keyIsExpired(redisDb *db, robj *key) {
    /* Don't expire anything while loading. It will be done later. */
    if (server.loading) return 0;

    mstime_t when = getExpire(db,key);
    mstime_t now;

    if (when < 0) return 0; /* No expire for this key */

    now = commandTimeSnapshot();

    /* The key expired if the current (virtual or real) time is greater
     * than the expire time of the key. */
    return now > when;
}

void dictResetIterator(dictIterator *iter)
{
    if (!(iter->index == -1 && iter->table == 0)) {
        if (iter->safe)
            dictResumeRehashing(iter->d);
        else
            assert(iter->fingerprint == dictFingerprint(iter->d));
    }
}

void dictReleaseIterator(dictIterator *iter)
{
    dictResetIterator(iter);
    zfree(iter);
}

-- @Filename: insert_keys.lua
-- @Usage:
-- redis-cli --eval insert_keys.lua
for i = 1, 10000000 do
    redis.call("SET", "my_test_key:index:" .. i, "value_" .. math.random(1, 10000000000))
end
return "Done"