Function scanGenericCommand

src/db.cpp:1175–1347

 * of every element on the Hash. */
void scanFilterAndReply(client *c, list *keys, sds pat, sds type, int use_pattern, robj_roptr o, unsigned long cursor);
void scanGenericCommand(client *c, robj_roptr o, unsigned long cursor) {
    int i, j;
    list *keys = listCreate();
    long count = 10;
    sds pat = NULL;
    sds type = NULL;
    int patlen = 0, use_pattern = 0;
    dict *ht;

    /* Object must be NULL (to iterate keys names), or the type of the object
     * must be Set, Sorted Set, or Hash. */
    serverAssert(o == nullptr || o->type == OBJ_SET || o->type == OBJ_HASH ||
                o->type == OBJ_ZSET);

    /* Set i to the first option argument. The previous one is the cursor. */
    i = (o == nullptr) ? 2 : 3; /* Skip the key argument if needed. */

    /* Step 1: Parse options. */
    while (i < c->argc) {
        j = c->argc - i;
        if (!strcasecmp(szFromObj(c->argv[i]), "count") && j >= 2) {
            if (getLongFromObjectOrReply(c, c->argv[i+1], &count, NULL)
                != C_OK)
            {
                goto cleanup;
            }

            if (count < 1) {
                addReplyErrorObject(c,shared.syntaxerr);
                goto cleanup;
            }

            i += 2;
        } else if (!strcasecmp(szFromObj(c->argv[i]), "match") && j >= 2) {
            pat = szFromObj(c->argv[i+1]);
            patlen = sdslen(pat);

            /* The pattern always matches if it is exactly "*", so it is
             * equivalent to disabling it. */
            use_pattern = !(pat[0] == '*' && patlen == 1);

            i += 2;
        } else if (!strcasecmp(szFromObj(c->argv[i]), "type") && o == nullptr && j >= 2) {
            /* SCAN for a particular type only applies to the db dict */
            type = szFromObj(c->argv[i+1]);
            i+= 2;
        } else {
            addReplyErrorObject(c,shared.syntaxerr);
            goto cleanup;
        }
    }

    if (o == nullptr && count >= 100 && !(serverTL->in_eval || serverTL->in_exec))
    {
        // Do an async version
        if (c->asyncCommand(
            [c, keys, pat, type, cursor, count, use_pattern] (const redisDbPersistentDataSnapshot *snapshot, const std::vector<robj_sharedptr> &) {
                sds patCopy = pat ? sdsdup(pat) : nullptr;