[WIP] switch usages of log to tokio_trace

[cosmicexplorer]

This PR is on top of #7342, and should be merged after that one, if we decide to adopt tokio-trace.

Problem

tokio-trace is a tracing framework for asynchronous rust programs (which does not depend on tokio!). The developer gave a talk describing what it is, how it works, and how it can be used: a recording is here. The ability to define spans and events is analogous to distributed tracing systems such as zipkin, which is the subject of #7342. It's possible that adopting tokio-trace will make this process easier and more automatic -- for example (shown in the talk), a .instrument() futures combinator is available via tokio-trace-futures which will very concisely create a span around the execution of the future!

Solution

One of tokio-trace's features (via tokio-trace-log) is being able to be dropped into rust programs using log without too many changes. A demo in the linked talk shows how logs can actually be converted into tokio-trace events by using a logger which emits these events.

This PR drops in tokio-trace_log::LogTracer to convert logs into trace events, which at this point are still just emitted as logs.

Result

Nothing changes at all, but this enables tracing via tokio-trace.

TODO

• Figure out where to put the tokio-trace subscriber.
• Demonstrate that tokio-trace can effectively integrate with the rest of our existing zipkin tracing (very exciting!).
• Demonstrate some usage of tokio-trace that provides value over log.

[Eric-Arellano]

Stale?

[Eric-Arellano]

Bump that I suspect this is also stale / can be closed? We've made lots of simplifications to the logging infrastructure recently, such as #10686.

[Eric-Arellano]

Closing as stale. Feel free to reopen if you plan to revive it.

[cosmicexplorer]

Yes! That’s appropriate! Thanks!