[boskid][2.0.20] Read full belt content on very long belt loop halts the game when the belt is cut

[yuu6883dev]

A very long belt for storing some rocks:

image (37).jpg (675.47 KiB) Viewed 817 times

Top left I'm reading belt content
Delete any section of the belt and the game halts (probably infinite loop)
No crash log / nothing abnormal in game log / no output after halt
100% reproducible on my side (tried at least 5 times)
Blueprint of entire ship is attached (belt.txt), don't think the save file has any use.
Issue is not seen when I'm not reading full belt content and cutting the belt

[boskid]

Its not infinite loop, it looks like it is O(N^2) where N is amount of belt belt pieces: when removing 1 belt piece there is code that tries to span transport line nicely, but before doing so it cuts the entire sequence into 1 tile long pieces (this is the first N) and when every piece is created, belt reader is propagated backward and forward (this is the second N). I may have some ideas how to improve this slightly, but this really feels like one of the "stop shooting yourself into your foot from the artillery cannot" case.

[yuu6883dev]

hmm, can the belt reader be propagated after the new lines are formed? It would still be O(N).
By any means, this is a really niche situation that I can work around.

[boskid]

Ok, it looks like by adding a strategic one line of code in one specifc place fixes this issue completly without even need to rewrite the remerge logic. So this issue should be now fixed for 2.0.22.

[yuu6883dev]

Thanks for the quick fix!

[boskid]

Ok, i did also another optimization on top of the previous one, a rewirite of the remerge logic and now my setup that consists of 250k of transport belts connected in sequence with belt reader active, when removing a belt takes about 8ms for the remerge operation which is hardly noticable. In 2.0.21 that same setup was taking way more than 5 minutes (i never saw it finish) so i am going to call it a success.

[afr33sl4ve]

Resolved this too: viewtopic.php?f=49&t=121997

Ty, boskid and yuu6883dev.