Some 32 bit platforms are not supported

[navaati]

I’m trying to use this library on a 32-bit platform (an ESP32-C3 chip, RISC-V based, has alloc and std).

However when building I get this error:

$ cargo check
    Checking prometheus-client v0.22.2
error[E0432]: unresolved import `std::sync::atomic::AtomicU64`
  --> /home/navaati/.cargo/registry/src/index.crates.io-6f17d22bba15001f/prometheus-client-0.22.2/src/metrics/counter.rs:10:5
   |
10 | use std::sync::atomic::AtomicU64;
   |     ^^^^^^^^^^^^^^^^^^^---------
   |     |                  |
   |     |                  help: a similar name exists in the module: `AtomicU32`
   |     no `AtomicU64` in `sync::atomic`

error[E0432]: unresolved import `std::sync::atomic::AtomicU64`
  --> /home/navaati/.cargo/registry/src/index.crates.io-6f17d22bba15001f/prometheus-client-0.22.2/src/metrics/exemplar.rs:17:5
   |
17 | use std::sync::atomic::AtomicU64;
   |     ^^^^^^^^^^^^^^^^^^^---------
   |     |                  |
   |     |                  help: a similar name exists in the module: `AtomicU32`
   |     no `AtomicU64` in `sync::atomic`

error[E0432]: unresolved imports `std::sync::atomic::AtomicI64`, `std::sync::atomic::AtomicU64`
  --> /home/navaati/.cargo/registry/src/index.crates.io-6f17d22bba15001f/prometheus-client-0.22.2/src/metrics/gauge.rs:11:25
   |
11 | use std::sync::atomic::{AtomicI64, AtomicU64};
   |                         ^^^^^^^^^  ^^^^^^^^^ no `AtomicU64` in `sync::atomic`
   |                         |
   |                         no `AtomicI64` in `sync::atomic`

My platform doesn’t support 64 bit atomics. Would there be a way to drop down to 32 bit atomics, perhaps with config detections, or a feature flag ?

[navaati]

Ah ! I realize it is actually supported, just for certain listed platforms:

client_rust/src/metrics/counter.rs

Lines 9 to 10 in bf196d7

	#[cfg(not(any(target_arch = "mips", target_arch = "powerpc")))]
	use std::sync::atomic::AtomicU64;

I’ll make a PR for ESPs.

[navaati]

Related previous PRs: #37 #42 .

[navaati]

#202 is a narrow fix, but I’d like a more general solution using target_has_atomic which is meant for this. Can still be merged in the meantime though.

[navaati]

#203 is the better fix but a bit of a bigger change (and I have not tested for regular PC class platforms, but I guess CI will).

[navaati]

Hi @mxinden, can you take a look at the PR for this ? It’s pretty simple. Even better if you can also look at related #206 :).

[zestysoft]

I just ran into this too -- in my case it's an armv5 system. https://github.com/rp-/tigo-exporter/issues/3