[Week 3/4] Evering Async Uring; Evering Driver with Lock; Evering Tokio

[lvyuemeng]

Caveat

本人第三周因为学习物理，以及其他的脚本项目并没有完全推进该项目，因此第三周与第四周合并记录保证连贯性。

Summary

• Evering Uring: A asynchronization of uring, thus we separate to sync/asynch compiled time choice.

• Evering Driver: Attempt to fully qualify the driver design, a quick read/write cache, currently we use Lock related api
  to allow multi-thread case. However, it will become the bottleneck compared to Uring channel; construct Bridge to separate
  the roles of submit and Complete, thus we can separate backend and frontend of driver; SQEHandle a polymorphism to adapt multiple strategies for CQ.

• Evering Tokio: A basic example based on tokio runtime, shown a easier use.

Problem

The basic problem stems from the lock, a another choice is to use a lock free, no-std, arena/slab-like data structure.
However, current selections can't satisfy above, like SkipList, which is not *slab-like`.

Current choice is ObjectPool, which is a data structure providing objects which lifetime carrys with the data structure itself.
We can provide a multi-ownership for such object to record and modify it, since each of them is independent.