fix: don't create static variables containing a tokio::runtime::Handle #38
+29
−44
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There was a bug in the approach implemented in smol-rs#30. The issue could manifest as a panic with message: "A Tokio 1.x context was found, but it is being shutdown." This would occur in the following scenario: 1. `.compat()` was used within a tokio context other than the fallback runtime. 2. That runtime was shutdown. 3. `.compat()` was used again. The root cause being that we had a `Handle` stored in a `static` global. `Handle`s are weak by design, and cannot prevent the runtime from shutting down. I reverted most of the changes in smol-rs#30 and instead added a `get_runtime_handle` function. This function attempts to acquire an existing runtime handle with `try_current` before creating a fallback runtime. This should be safe because `try_current` will only succeed within the scope of a tokio runtime context, and it cannot outlive that scope.
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The Bug
There was a bug in the approach implemented in #30.
The issue could manifest as a panic with message:
"A Tokio 1.x context was found, but it is being shutdown."
This would occur in the following scenario:
.compat()was used within a tokio context other than the fallback runtime..compat()was used again.The root cause being that we had a
Handlestored in astaticglobal.Handles are weak by design, and cannot prevent the runtime from shutting down.The Fix
I reverted most of the changes in #30 and instead added a
get_runtime_handlefunction. This function attempts to acquire an existing runtime handle withtry_currentbefore creating a fallback runtime. This should be safe becausetry_currentwill only succeed within the scope of a tokio runtime context, and it cannot outlive that scope.