Method pop_request

src/media_reader/src/frame_request_queue.cpp:62–85

}

std::optional<FrameRequest>
FrameRequestQueue::pop_request(
    const std::map<utility::Uuid, int> &in_flight_frame_requests_per_playhead,
    const size_t max_num_inflight_requests) {
    std::optional<FrameRequest> rt = {};

    for (auto p = queue_.begin(); p != queue_.end(); p++) {
        auto q = in_flight_frame_requests_per_playhead.find((*p)->requesting_playhead_uuid_);
        // logic here is as follows: if there are no in-flight requests for this playhead, we can pop the request. 
        // If there are in-flight requests but the number of in-flight requests is less than the max allowed, 
        // then we can pop the request if it is NOT for a containerised encoding. If we have multiple frame requests
        // in-flight for containerised media (like mp4) the a-sync nature of the media reader workers and cache means
        // the frames will ultimately be read out-of-order. This can kill performance for readers like mp4 which have
        // motion encoding with I fra
        if (q == in_flight_frame_requests_per_playhead.end() || 
            ((*p)->requested_frame_ && !(*p)->requested_frame_->is_containerised_encoding() && size_t(q->second) < max_num_inflight_requests)
        ) {
            rt = *(*p);
            queue_.erase(p);
            break;
        }
    }
    return rt;
}

void FrameRequestQueue::prune_stale_frame_requests() {