Make Logging work better for Performance and Health Monitoring

[mollyling]

Currently, the logging system misses a few features that would help us make uProxy faster and more reliable.

First and foremost, many uProxy log messages don't show up in the text console log (e.g., --enable-logging). Instead, we get "%c RtcToNet", followed by source: chrome-extension://lots-of-unhelpful-text/fredom-for-chrome.js.

Life would be substantially better if we could capture logs to a file and grep for the messages that we care about.

Performance-wise, we could definitely use two other changes:

• Buffer log messages into bursts to write out, reducing the system overhead.
• Provide an api for us to test whether a log message is worth generating at all. Sometimes a log message, particularly one for performance tracing, can involve some work to generate. We may collect data, calculate averages, call chrome APIs, etc. It'd be nice if we could avoid that work altogether if the message isn't going to go anywhere

[mollyling]

Also, to support #1015, it'd be nice to easily let another component listen for certain kinds of log messages, so that a status-page component can monitor instrumentation data.

[trevj]

So, regarding your second point, I think this issue covers making src/logging/logging.ts skip (potentially expensive) logging if it's just gonna be discarded:
#1005

[trevj]

Oh! The logging provider in uproxy-lib already lets us query logs:
https://github.com/uProxy/uproxy-lib/blob/dev/src/loggingprovider/loggingprovider.ts

We don't use that feature today but I think it's what you're looking for?

[trevj]

It looks like @soycode is looking at the console issue here:
freedomjs/freedom#239

Right now, the logging provider will only store 1000 lines and this value is hard-coded:
https://github.com/uProxy/uproxy-lib/blob/dev/src/loggingprovider/loggingprovider.ts#L15

Its default is E so I guess it was intended only for capturing the worst errors, not profiling. @mollyling do you think it's worth adding a call to set that programmatically, e.g. setBufferedLogSize?

[iislucas]

I think that's a good idea. (adding setBufferedLogSize).

[trevj]

I don't see what this issue is doing for us, given this more specific issue:
#1005