Function RM_StreamIteratorStart

app/redis-6.2.6/src/module.c:3472–3509

Sets up a stream iterator. * * - `key`: The stream key opened for reading using RedisModule_OpenKey(). * - `flags`: * - `REDISMODULE_STREAM_ITERATOR_EXCLUSIVE`: Don't include `start` and `end` * in the iterated range. * - `REDISMODULE_STREAM_ITERATOR_REVERSE`: Iterate in reverse order, starting * from the `end` of the range. * - `start`: The lower bound of the range. Use NULL f

 *     RedisModule_StreamIteratorStop(key);
 */
int RM_StreamIteratorStart(RedisModuleKey *key, int flags, RedisModuleStreamID *start, RedisModuleStreamID *end) {
    /* check args */
    if (!key ||
        (flags & ~(REDISMODULE_STREAM_ITERATOR_EXCLUSIVE |
                   REDISMODULE_STREAM_ITERATOR_REVERSE))) {
        errno = EINVAL; /* key missing or invalid flags */
        return REDISMODULE_ERR;
    } else if (!key->value || key->value->type != OBJ_STREAM) {
        errno = ENOTSUP;
        return REDISMODULE_ERR; /* not a stream */
    } else if (key->iter) {
        errno = EBADF; /* iterator already started */
        return REDISMODULE_ERR;
    }

    /* define range for streamIteratorStart() */
    streamID lower, upper;
    if (start) lower = (streamID){start->ms, start->seq};
    if (end)   upper = (streamID){end->ms,   end->seq};
    if (flags & REDISMODULE_STREAM_ITERATOR_EXCLUSIVE) {
        if ((start && streamIncrID(&lower) != C_OK) ||
            (end   && streamDecrID(&upper) != C_OK)) {
            errno = EDOM; /* end is 0-0 or start is MAX-MAX? */
            return REDISMODULE_ERR;
        }
    }

    /* create iterator */
    stream *s = key->value->ptr;
    int rev = flags & REDISMODULE_STREAM_ITERATOR_REVERSE;
    streamIterator *si = zmalloc(sizeof(*si));
    streamIteratorStart(si, s, start ? &lower : NULL, end ? &upper : NULL, rev);
    key->iter = si;
    key->u.stream.currentid.ms = 0; /* for RM_StreamIteratorDelete() */
    key->u.stream.currentid.seq = 0;
    key->u.stream.numfieldsleft = 0; /* for RM_StreamIteratorNextField() */
    return REDISMODULE_OK;
}

/* Stops a stream iterator created using RedisModule_StreamIteratorStart() and
 * reclaims its memory.