Glue code for working with tokio's async I/O.
This is mostly smaller things that happen to recur in our particular
application.
| run_futures_with_runtime | Create a new tokio runtime and use it to run cmd_future (which carries
out whatever task we want to perform), and worker_future (which should
have been created by Context::create or Context::create_for_test).
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| BoxFuture | Standard future type for this library. Like Result, but used by async. We
mark it as Send to ensure it can be sent between threads safely (even when
blocked on .await!), and we Pin<Box<...>> it using .boxed() to make it
an abstract, heap-based type, for convenience. All we know is that it will
return a Result<T>.
|
| BoxStream | A stream of values of type T, using our standard error type, and imposing
enough restrictions to be able send streams between threads.
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