does not build on MIPS

[nazar554]

I can't build quanta 0.3.1 with mipsel-unknown-linux-musl target. Should it still build and fallback to OS facilities?
Is there any workaround to use it with metrics-runtime?

Found this in docs for std::sync::atomic:

PowerPC and MIPS platforms with 32-bit pointers do not have AtomicU64 or AtomicI64 types.

error[E0432]: unresolved import `std::sync::atomic::AtomicU64`
  --> /cargo/registry/src/github.com-1ecc6299db9ec823/quanta-0.3.1/src/lib.rs:51:14
   |
51 |     atomic::{AtomicU64, Ordering},
   |              ^^^^^^^^^
   |              |
   |              no `AtomicU64` in `sync::atomic`
   |              help: a similar name exists in the module: `AtomicU8`

error[E0432]: unresolved import `std::sync::atomic::AtomicU64`
 --> /cargo/registry/src/github.com-1ecc6299db9ec823/quanta-0.3.1/src/mock.rs:5:18
  |
5 |         atomic::{AtomicU64, Ordering},
  |                  ^^^^^^^^^
  |                  |
  |                  no `AtomicU64` in `sync::atomic`
  |                  help: a similar name exists in the module: `AtomicU8`

error: aborting due to 2 previous errors

[tobz]

I'll see if I can backport your PR to an 0.3 version of quanta and potentially do a patch release to help ya out.

[nazar554]

I have a feature/atomic-shim-0.3.1 branch in my fork, it seems to build already. I addeda #[ctor] hack for static initializtion of AtomicU64

[tobz]

Nice. I created a branch, 0.3-lts, based off of the 0.3.1 commit. If you want to submit that feature branch as a PR, based against the LTS branch, we can get that going as well, and hopefully released quickly.

[messense]

Compilation error when cross compile to MIPS (mipsel-unknown-linux-musl).

   Compiling quanta v0.9.2
error[E0599]: no method named `fetch_add` found for struct `Arc<AtomicCell<u64>>` in the current scope
  --> /root/.cargo/registry/src/github.com-1ecc6299db9ec823/quanta-0.9.2/src/mock.rs:48:21
   |
48 |         self.offset.fetch_add(amount.into_nanos());
   |                     ^^^^^^^^^ method not found in `Arc<AtomicCell<u64>>`

error[E0599]: no method named `fetch_sub` found for struct `Arc<AtomicCell<u64>>` in the current scope
  --> /root/.cargo/registry/src/github.com-1ecc6299db9ec823/quanta-0.9.2/src/mock.rs:53:21
   |
53 |         self.offset.fetch_sub(amount.into_nanos());
   |                     ^^^^^^^^^ method not found in `Arc<AtomicCell<u64>>`

error: aborting due to 2 previous errors

[nazar554]

@messense crossbeam disables 64-bit atomics on unsupported platforms (with crossbeam_no_atomic_64 feature)
See crossbeam-rs/crossbeam#731

Can be fixed by not using crossbeam on MIPS & PowerPC, or implementing support for atomic_shim there as well