ffi VS dd-trace-rb

If you're working with Ruby and need to invoke a function written in C language, there are some convenient gems available: Ruby-FFI and Fiddle.

Could this be related to spaces in the directory/this issue: https://github.com/ffi/ffi/issues/623? If so, there's no suggestion on the issue, but https://stackoverflow.com/a/64083281 (including the comment https://stackoverflow.com/questions/62368342/rails-bundle-cant-install-gem-ffi#comment123868330_64083281), might help.

Hey, Oso engineer here. Good question.

The rust core is indeed called from the ruby library (as it is with all of our 5 other host libraries). The core itself is pretty complex (there's a whole parser/interpreter in there), so maintaining it in a bunch of languages would be a bit hectic.

There are some files inside `lib/oso/polar/ffi` that define the C bindings used by the rest of the library. Here's an example: https://github.com/osohq/oso/blob/main/languages/ruby/lib/os...

We use the ffi gem to make that work: https://github.com/ffi/ffi

Ruby-FFI is a powerful tool to create bindings for C language libraries in Ruby.

Tried solution mentioned here https://github.com/ffi/ffi/issues/653 but no luck then I posted this question over StackOverflow :

Thing is, once you have 1) and 2), the added complexity of bringing in, integrating, and writing for a different tool to achieve 3) begins to make little sense, when you can just go along and do it just as well in rspec anyway... It's a matter of balance and heavily depends on the project.

> if you're still at Datadog

As a matter of fact I am. Feel free to shoot me an email.

    curl -s https://github.com/DataDog/dd-trace-rb/commit/176c642ca73679cabc5fa1a113bc9b600aa04dcd.patch | grep '^From:'

> For myself, I'm fine with the typing being in a separate .rbs file

We type[0] by having one separate .rbs file per .rb file. Works really well with an editor's vertical splits: type outline on one side, code on the other. That, or use something like vim-projectionist[1].

[0]: (WIP: there's a huge codebase to type, but we're progressively getting there) https://github.com/DataDog/dd-trace-rb/tree/master/sig

[1]: https://github.com/tpope/vim-projectionist

Thanks! I'll pass it on to the team :D

I've got to say, the folks at Intercom made it particularly fun. They were sending us traces and graphs from their internal systems when we trying to figure out some issues with them (e.g. we ran into this datadog context problem: https://github.com/DataDog/dd-trace-rb/issues/1389)