支持 Monoio 作为可选的 Runtime about volo

[PureWhiteWu]

@ThaddeusTreloar Hello, sorry for the late reply, I'm busy refactoring the Service trait these days.
I've finally refactored the Service trait in motore to use afit and rpitit, which can easily switch between Send and ?Send version by a feature flag.
And I've also migrated volo to use the new Service trait in motore in #239 .
You may try to overcome the Send problem now.

[ThaddeusTreloar]

Happy to be assigned this if you've not found anyone else.

I had a look through the source and the task doesn't look too bad. Even in the dependencies, it doesn't look like there are many calls to Tokio runtime specific code.

[PureWhiteWu]

Wow! Great you would like to help!
We are redesigning our motore::Service trait to use rpitit, after that it will be more easy to support monoio as an opt-in runtime.

[ThaddeusTreloar]

I've done most of the preliminary work so that you can enable a feature flag and the runtime will swap. It currently continues to use non runtime specific Tokio components where possible (eg. AsyncRead/AsyncWrite).

The feature is currently blocked as there are several instances where a tokio::time::Sleep is returned in a future bound with Send. Unfortunately the Monoio equivalent is not thread safe and therefore not Send. I'm currently working to refactor the Monoio implementation (which is largely derived from Tokio 's version) to be Send.

[iamazy]

I'm eager about this feature