Crash - assertion failed.

[centaur1]

This happens reasonably often.

assertion failed. Please file a bugreport at https://github.com/miguelfreitas/twister-core/issues
Please include the following information:

version: 1.0.0.0
$Rev: 7680 $
file: 'libtorrent/src/torrent.cpp'
line: 3066
function: void libtorrent::torrent::piece_finished(int, int, boost::uint32_t, int)
expression: !m_picker->have_piece(index)

stack:
1: assert_fail(char const*, int, char const*, char const*, char const*)
2: libtorrent::torrent::piece_finished(int, int, unsigned int, int)
3: boost::detail::function::void_function_obj_invoker2<boost::_bi::bind_t<void, boost::_mfi::mf4<void, libtorrent::torrent, int, int, unsigned int, int>, boost::_bi::list5<boost::_bi::value<boost::shared_ptrlibtorrent::torrent >, boost::_bi::value, boost::arg<1>, boost::arg<2>, boost::_bi::value > >, void, int, unsigned int>::invoke(boost::detail::function::function_buffer&, int, unsigned int)
4: libtorrent::torrent::on_piece_verified(int, libtorrent::disk_io_job const&, boost::function<void (int, unsigned int)>)
5: void boost::_mfi::mf3<void, libtorrent::torrent, int, libtorrent::disk_io_job const&, boost::function<void (int, unsigned int)> >::call<boost::shared_ptrlibtorrent::torrent, int, libtorrent::disk_io_job const, boost::function<void (int, unsigned int)> >(boost::shared_ptrlibtorrent::torrent&, void const*, int&, libtorrent::disk_io_job const&, boost::function<void (int, unsigned int)>&) const
6: void boost::_bi::list4<boost::_bi::value<boost::shared_ptrlibtorrent::torrent >, boost::arg<1>, boost::arg<2>, boost::_bi::value<boost::function<void (int, unsigned int)> > >::operator()<boost::_mfi::mf3<void, libtorrent::torrent, int, libtorrent::disk_io_job const&, boost::function<void (int, unsigned int)> >, boost::_bi::list2<int&, libtorrent::disk_io_job const&> >(boost::_bi::type, boost::_mfi::mf3<void, libtorrent::torrent, int, libtorrent::disk_io_job const&, boost::function<void (int, unsigned int)> >&, boost::_bi::list2<int&, libtorrent::disk_io_job const&>&, int)
7: boost::detail::function::void_function_obj_invoker2<boost::_bi::bind_t<void, boost::_mfi::mf3<void, libtorrent::torrent, int, libtorrent::disk_io_job const&, boost::function<void (int, unsigned int)> >, boost::_bi::list4<boost::_bi::value<boost::shared_ptrlibtorrent::torrent >, boost::arg<1>, boost::arg<2>, boost::_bi::value<boost::function<void (int, unsigned int)> > > >, void, int, libtorrent::disk_io_job const&>::invoke(boost::detail::function::function_buffer&, int, libtorrent::disk_io_job const&)
8: libtorrent::completion_queue_handler(std::__1::list<std::__1::pair<libtorrent::disk_io_job, int>, std::__1::allocator<std::__1::pair<libtorrent::disk_io_job, int> > >)
9: void boost::asio::asio_handler_invoke<boost::_bi::bind_t<void, void ()(std::__1::list<std::__1::pair<libtorrent::disk_io_job, int>, std::__1::allocator<std::__1::pair<libtorrent::disk_io_job, int> > >), boost::_bi::list1<boost::_bi::value<std::__1::list<std::__1::pair<libtorrent::disk_io_job, int>, std::__1::allocator<std::__1::pair<libtorrent::disk_io_job, int> > >> > > >(boost::_bi::bind_t<void, void ()(std::__1::list<std::__1::pair<libtorrent::disk_io_job, int>, std::__1::allocator<std::__1::pair<libtorrent::disk_io_job, int> > >), boost::_bi::list1<boost::_bi::value<std::__1::list<std::__1::pair<libtorrent::disk_io_job, int>, std::__1::allocator<std::__1::pair<libtorrent::disk_io_job, int> > >> > >&, ...)
10: boost::asio::detail::completion_handler<boost::_bi::bind_t<void, void ()(std::__1::list<std::__1::pair<libtorrent::disk_io_job, int>, std::__1::allocator<std::__1::pair<libtorrent::disk_io_job, int> > >), boost::_bi::list1<boost::_bi::value<std::__1::list<std::__1::pair<libtorrent::disk_io_job, int>, std::__1::allocator<std::__1::pair<libtorrent::disk_io_job, int> > >> > > >::do_complete(void*, boost::asio::detail::scheduler_operation*, boost::system::error_code const&, unsigned long)
11: boost::asio::detail::scheduler::do_run_one(boost::asio::detail::conditionally_enabled_mutex::scoped_lock&, boost::asio::detail::scheduler_thread_info&, boost::system::error_code const&)
12: boost::asio::detail::scheduler::run(boost::system::error_code&)
13: boost::asio::io_context::run(boost::system::error_code&)
14: libtorrent::aux::session_impl::main_thread()
15: boost::asio::detail::posix_thread::func<boost::_bi::bind_t<void, boost::_mfi::mf0<void, libtorrent::aux::session_impl>, boost::_bi::list1<boost::_bi::valuelibtorrent::aux::session_impl* > > >::run()
16: boost_asio_detail_posix_thread_function
17: _pthread_body
18: _pthread_body
19: thread_start

[centaur1]

The way to duplicate this is if you do this:
If twisterd has returned null from something like this:
/usr/name/twister-core/twisterd getposts 1 '[{"username":"whateveruser"}]'
[
]

and then you attempt to do a post like this:
/usr/name/twister-core/twisterd newpostmsg whateveruser 1 'something here https://google.com'

It will crash as above. I've duplicated it about a dozen times so far with tests. I presume it is because it is busy fetching information on that user, hence the
"!m_picker->have_piece(index)"

In short, if someone tries to post for a particular user while it is still fetching for that particular user, it crashes from my testing.

So one can mitigate it by checking to see if NULL is returned from a twisterd call checking a user prior to attempting to post their post. It shouldn't crash of course, but at least one can check for the condition prior to doing a post.

In case anyone else sees that, at least it can be mitigated.

[centaur1]

What I ended up doing besides just checking it is to programmatically do a
unfollow <username> '["<username>"]'
followed by a
follow ... as above

This seems to be the same error as is checked in the html interface with the message:
Internal error: lastPostId unknown (following yourself may fix!)": "Internal error: lastPostId unknown (following yourself may fix!)

[miguelfreitas]

Hi @centaur1. Thank you very much for your investigation!
It is great that you have found a way to reproduce it, as it makes fixing a much easier job :-)
I just can't promise when I'll be able to look into that issue because I'm quite busy at work these days...

[centaur1]

If I can dig more into the code, I'll post it here. It seems to be really two related issues:

1. The assertion issue.
2. The "Internal error: lastPostId unknown" that is found in twister-html.

I think they are related in that if the lastPostId is unknown (the torrent hasn't been fetched yet either) then one would be using an incorrect K value.

My "fix" was doing a dhtget, unfollow, and then follow.

I am not sure about all that though since I am still progressing on it.