download_store.cc save() FUNCTION IMPROVEMENT

[adambarta]

Wondering if there is a way to skip this function if long term seeding torrents haven't been accessed in a typical 1200s session

main.cc
358 "schedule2 = session_save,1200,1200,((session.save))\n"

download_store.cc
bool
DownloadStore::save(Download* d, int flags) {
if (!is_enabled())
return true;

something added to the branch with !is_enabled() || !has_stats_changed(d)

would defiantly decrease the lagg caused. also when this happens while active seeding or leeching there is a loss in data transfer performance since the thread is hogging to storage.

seems to become noticeable at 500+ active torrents.

[rakshasa]

There are more optimizations that could be done, e.g. do it in chunks, have a separate thread that does the I/O related work, etc.

[adambarta]

I agree on the separate thread. That would definitely alleviate the data transfer performance loss.
I have some idea of the thread implementation. Can you give some advice of which functions to look at, locking with pthread_mutex_t etc?. If i want to implement a d->has_stats_changed() or has_stats_changed(d) what advice can you give is there already a bit toggled in the flags once the data read from session start is updated? how can this be implemented? I am working on 0.15.1 source btw.
`
bool
DownloadStore::save(Download* d, int flags) {
if (!is_enabled() /*|| !d->has_stats_changed() */)
return true;

torrent::Object* resume_base = &d->download()->bencode()->get_key("libtorrent_resume");
torrent::Object* rtorrent_base = &d->download()->bencode()->get_key("rtorrent");

// Move this somewhere else?
rtorrent_base->insert_key("chunks_done", d->download()->file_list()->completed_chunks());
rtorrent_base->insert_key("chunks_wanted", d->download()->data()->wanted_chunks());
rtorrent_base->insert_key("total_uploaded", d->info()->up_rate()->total());
rtorrent_base->insert_key("total_downloaded", d->info()->down_rate()->total());

// Don't save for completed torrents when we've cleared the uncertain_pieces.
torrent::resume_save_progress(*d->download(), *resume_base);
torrent::resume_save_uncertain_pieces(*d->download(), *resume_base);

torrent::resume_save_addresses(*d->download(), *resume_base);
torrent::resume_save_file_priorities(*d->download(), *resume_base);
torrent::resume_save_tracker_settings(*d->download(), *resume_base);

// Temp fixing of all flags, move to a better place:
resume_base->set_flags(torrent::Object::flag_session_data);
rtorrent_base->set_flags(torrent::Object::flag_session_data);

//move this to a worker_thread(d, &write_data_call)
/*
std::string base_filename = create_filename(d);

if (!write_bencode(base_filename + ".libtorrent_resume.new", *resume_base, 0) ||
!write_bencode(base_filename + ".rtorrent.new", *rtorrent_base, 0))
return false; ::rename((base_filename + ".libtorrent_resume.new").c_str(), (base_filename + ".libtorrent_resume").c_str()); ::rename((base_filename + ".rtorrent.new").c_str(), (base_filename + ".rtorrent").c_str());

if (!(flags & flag_skip_static) &&
write_bencode(base_filename + ".new", *d->bencode(), torrent::Object::flag_session_data))
::rename((base_filename + ".new").c_str(), base_filename.c_str());
*/

return true; //have to collect the failure modes at the
}
`