[Lldb-commits] [PATCH] D107079: [lldb] Change the log format to JSON instead of plain text

Thu Jul 29 08:01:23 PDT 2021

teemperor added a comment.

I hacked together a quick example log viewer in HTML here: https://teemperor.de/pub/logviewer.html (I already loaded in a log from my machine, so you can just hit "parse log"). Note that you can search the log messages and you can click each one of them to reveal their associated stack trace. You can also export the log in a different format (Excel, CSV, etc.).

Some general notes:

- Why JSON? In LLVM we have pretty much just JSON and YAML as formats available (well, and the bitcode format I guess). YAML is a much more complicated format and the main idea here is to let people write tools, so JSON seemed like an obvious pick.

- Will there be an upstream log viewer? I don't know, but we could easily put a simple one on the website that just formats a log as a simple HTML table. That is easily done in vanilla JavaScript. But that should be a follow up patch.

- Do we want to keep the old plain text format too? To be honest, I don't really see much

- What about logs that are printed to stdin and we want to parse? I think you can easily make a tool that filters out the non-JSON output. Logs are guaranteed to have every object on its own line, so you can just go line-by-line and filter them based on that.

Some planned follow ups:

- Enable more logging meta-information by default. Things such as pid/tid seems like obvious cheap choices.

- For people that really like the old format, it should be a simple patch to add a converter that just takes a JSON file and outputs the old plaintext.

- I want to remove the ability to turn off thread-safe logging. It seems like it could potentially crash LLDB but it would certainly break the JSON parser. It's usually (and luckily) enabled by default anyway.

- Some more meta information would be actually helpful sometimes and there isn't any reason to not add them. E.g., classifying messages as error/warning/info.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107079/new/

https://reviews.llvm.org/D107079