Using the library in stable rust

[tailhook]

Is there any chance this kind of library be available for stable rust? It's ugly to use nightly just for adding USDT.

I don't know how this works internally to figure out way on my own. But maybe we can use some attributes like link_section for markers (or is it unstable too?). Or just use a piece of C code for embedding asm instead of using feature(asm) ?

[cuviper]

First off, I'm pleased that someone is still interested in this! 😄

Unfortunately, I don't see a real path forward without feature(asm). There's more to it than just declaring a section, especially all the content of that note. Some of it could be generated in a static byte array, but the probe address currently references a asm label. I don't know how you'd do that without the assembler and linker's cooperation.

You could do a bit of external C code already, using the original sdt.h in a function that Rust can call as FFI, but that means having a function call for every probe even when disabled. Maybe LTO could inline that -- I'm not sure.

There's an alternate rust-usdt which is a compiler plugin instead, but that's a nightly feature too, and it still needs feature(asm). See also their post on internals:
https://internals.rust-lang.org/t/tracing-in-rust-with-uprobes/4756

[No9]

@tailhook FYI I put together a sample to show how you wrap a C based USDT probe into a rust stable build
https://github.com/No9/rust-usdt-helloworld
It works but the flow has a few edges.

[cuviper]

Per #15, this now works on beta without unstable features, so it will be stable in Rust 1.59!