C++ Interface

[cinjon]

People have expressed interest in having a c++ interface so that the game could be simulated faster. This would be a larger endeavor and it would be great if we discussed what it would take and who would be keen to lead this here.

@tambetm @b-kartal @gorogm

[inoryy]

Hello,

I guess I can take the lead, I was planning to do this for my bot anyway . :)
I'm currently in discovery mode, deciding on how to specifically approach this. I will probably start actively developing towards the end of next week.

Any particular requirements/requests?

[dist1ll]

Hey I have already started with some basics.

I haven't updated the README because the source is quite raw.

https://github.com/m2q/nips2018-agent

• The state representation is in bboard.hpp
• The agents can be declared in agents.hpp

I supplied a make file and a run.sh shell script, running it should simulate a couple of steps
of the game with 4 random agents. The main.cpp has an exemplary Run() method.

The method bboard::Step(..) has some basic collision detection.

To really make this work I planned to integrate automatic unit testing, to really make sure
the behaviour exactly matches the pommerman source.

Edit: This was only tested on Ubuntu 18.04, uses g++ and c++11

[gorogm]

Hi @cinjon @inoryy @m2q,
It would be great! The 100 msec maximal response time seems thin for online search methods, so a C++ core would be really useful!

I know C++ doesn't have standard 2d drawing abilities, but I'm sure some basic visualization would also be helpful for any developers.

Later it would be nice if it had a prepared way to submit as a docker package with the needed interface.

I could give some time to develop one, let it be m2q's or an other one.

[b-kartal]

Hi all, I would be happy to give a hand as much as I can as well. I believe it will be very useful for particularly search based agents.

…

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On 10 Jun 2018, at 12:54, gorogm ***@***.***> wrote: Hi @cinjon @inoryy @m2q, It would be great! The 100 msec maximal response time seems thin for online search methods, so a C++ core would be really useful! I know C++ doesn't have standard 2d drawing abilities, but I'm sure some basic visualization would also be helpful for any developers. Later it would be nice if it had a prepared way to submit as a docker package with the needed interface. I could give some time to develop one, let it be m2q's or an other one. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or mute the thread.

[dist1ll]

I'm currently printing ascii to the console. Not ideal but you can see what's going on (at least for bricks and agents)

[suphoff]

@gorogm : Probably easier and more portable to just export the data in the existing json format using file/socket/tcp and just run the existing python rendering interface for visualization as needed for replay/debugging.

[suphoff]

FYI: There are still a few bugs in the agent/bomb movement code. @cinjon is reviewing a patch. I won't have time in the next 4 weeks to help - but I can explain the movement rules if needed. I wrote a small python script to set up bombs/agents to test the patch for the step function. Running a few scenarios on the script may help to understand desired behavior. (Too ugly and incomplete for github - ping me on discord if you want a copy )

[lucasb-eyer]

I think I'm missing something, why would a C++ interface make the game (which is still Python code) run faster? Or are you talking about a re-implementation in C++?

[cinjon]

You're right @lucasb-eyer. I should have been more clear. This isn't about creating a C++ coding interface, but about coding a C++ forward model so that the game can be simulated much more quickly. That would be a big help for a lot of model approaches.

[lucasb-eyer]

In that case (just to add my salt 😄 ) it might be better to do it in C, so that any language can easily interface to it.

[dist1ll]

I think C++ is fitting because there is a pytorch library for C++. Imo (and this is purely subjective) C makes lots of stuff unnecessarily complicated, especially string manipulation.

Also, I can't think of any language that would have trouble invoking C++ functions, afaik

[lucasb-eyer]

Also, I can't think of any language that would have trouble invoking C++ functions, afaik

No, all languages have trouble calling C++.

Because the C++ ABI is undefined, it is only possible to call into C++ safely from another language if that language (or language's FFI) has been compiled with the same major compiler version as the C++ code it should call. For instance, Python's ctypes can't call into C++. Actually, no language can call into C++ unless they somehow know how the C++ code was compiled. Hence why people need to create C interfaces (extern "C" {...}) to C++ libraries for calling them. Think about how another language would call a templated C++ function? It can't.

Edit to add that I don't disagree with you on C making things like strings more complicated, but being called from other languages is the one thing that C++ makes unnecessarily complicated.

[gorogm]

Let's remain practical, I smell we won't have enormous resources. @lucasb-eyer, are you planning to use the lib from any other programming language?