Shouldn't Multi be Send?

[jedenastka]

According to https://curl.se/libcurl/c/threadsafe.html, it is safe to pass handles across threads (it's not safe to use handles in multiple threads at once, which in Rust terms would mean they are !Sync), so shouldn't Multi be Send? It being !Send complicates some multithreaded code I'm writing: it seems that what I'm trying to do should be thread safe, however, the compiler prevents me from doing that due to !Send being implemented on Multi.

[jedenastka]

I tried implementing this here and it seems to be working well. I'm not 100% sure it is sound (don't have a lot of experience working with unsafe), but I tried it in some multithreaded situations, and my tests pass.

[jedenastka]

I believe my implementation might be unsound, as not all methods on the handles that interact with libcurl require a mutable reference (for example, Multi::remove2): my code always uses Mutex<Multi> and Mutex<Easy2Handle>, but I could not do that. In other words, implementing this properly would require a breaking change to the API.

[h3xOo]

Making it Send would also allow using it in tokio.