Clean Up Logging about processcache HOT 5 CLOSED

Sure! In PR #13 I have:

debug!("execve(\"{:?}\", {:?})", path_name, args);
trace!("envp={:?}", envp);

That is, when running on debug we print the path and args to execve, but only when running on trace do we print the environment variables (which might still be too verbose, even for trace).

In general I treat info as the default logging mode, which prints useful information for what is happening but not too verbose. debug is even more information but still relates to logical events hapenning, trace I like trace being verbose enough to understand what function is currently executing and sometimes even which code branch was taken. Lmk if that makes sense!

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The standard verbosity levels for Rust are as follow. Here is my recommended convention for logging output:

• Error: We usually panic on error as there isn't much need for us to recover from fatal errors so we probably won't use error.
• Warn: This is similar to error but it might be useful to warn in some situations. We should use warn for reporting issues to the user.
• Info: Info should be reserved for always relevant information. Some examples include: encountered an exec, new process spawned, ptrace event intercepted. Specific system call being handled.
• Debug: This is for low priority, but sometimes nice to have extra information.
  -Trace: Trace is extremely verbose and often tracks all function calls and events one might want to know about when debugging an issue.

It may seem that trace is like drinking from a fire hose, thankfully Rust and the Tracing crate allows us to filter events several ways, making it far easier to track only events we care about. This also needs to be considered when adding logging for the project. More on this to come...

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Thank you for listing these, I actually don't think I really knew about those! But I will definitely keep these in mind. I think the one I don't see the difference between is debug and trace. I think I usually them interchangeably, and I actually don't think I've really used trace. Could you give me an example of when to use one over the other?

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Yes that totally makes sense. Thank you for doing this!

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Done by @gatoWololo in #13

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