Logger.Translator.child_info/2 fails on supervisor reports including `:name`

[arkgil]

Hi there! I have a problem with Logger.Translator failing on supervisor reports with Elixir 1.6.6.

Environment

• Elixir & Erlang/OTP versions (elixir --version): 1.6.6 & 20.3 (or 19.3)
• Operating system: macOS High Sierra 10.13.1

Current behavior

Logger.Translator.child_info/2 fails on supervisor progress reports which include a name of the process, e.g. the one reported by supervisor3 - https://github.com/klarna/supervisor3/blob/master/src/supervisor3.erl#L1656.

The error looks as follows:

15:35:56.711 [error] :gen_event handler Logger.ErrorHandler installed at :error_logger
** (exit) an exception was raised:
    ** (FunctionClauseError) no function clause matching in Logger.Translator.child_info/2
        (logger) lib/logger/translator.ex:320: Logger.Translator.child_info(:debug, [name: LoggerTranslatorRepro.Server, mfargs: {Agent, :start_link, [#Function<0.78284505/0 in LoggerTranslatorRepro.init/1>, [name: LoggerTranslatorRepro.Server]]}, restart_type: :permanent, shutdown: 5000, child_type: :worker])
        (logger) lib/logger/translator.ex:240: Logger.Translator.report_supervisor_progress/2
        (logger) lib/logger/erlang_handler.ex:104: Logger.ErlangHandler.translate/6
        (logger) lib/logger/erlang_handler.ex:97: Logger.ErlangHandler.translate/5
        (logger) lib/logger/error_handler.ex:93: Logger.ErrorHandler.log_event/6
        (logger) lib/logger/error_handler.ex:33: Logger.ErrorHandler.handle_event/2
        (stdlib) gen_event.erl:574: :gen_event.server_update/4
        (stdlib) gen_event.erl:556: :gen_event.server_notify/4

This happens on Elixir 1.6.6, I couldn't observe this error on 1.5.3. Most probably the issue was introduced in the PR bringing integration with Erlang 21 logger, this deletion removed the clause which handled the name of the child process.

If anyone's interested, here is the repo to reproduce the error.

Expected behavior

Logger.Translator properly handles and prints out progress reports with process names.

I'll be happy to prepare a PR for this, if it's not intentional. If the change was intentional, maybe a good idea would be to log a warning when translator receives the report it can't handle?

[josevalim]

@arkgil a PR will be very welcome. :)

[arkgil]

@josevalim on it :)

[arkgil]

@josevalim now that I think about it - Erlang's and Elixir's supervisors always report child info with id key. This means that we can't test if the name is really picked up, and that we'll be trying to conform to 3rd party lib. Maybe a better idea would be to log, or at least ignore the report? Unfortunately current behaviour makes the Logger application crash, ultimately bringing down the apps which use Logger 😢

[josevalim]

@arkgil yes it is important that we don't crash. :) We can probably just ignored malformed data. Although I believe those crashes will be unlikely when using OTP 21.