Log 0.4 support

[jacekchmiel]

No description provided.

[dpc]

Anyone interested in owning this crate? :D

[belltoy]

@dpc I can take this crate if you may

[dpc]

@belltoy Please submit PRs, so I can gain some confidence, and then it's yours.

[rohitjoshi]

When are we releasing this support? @tanriol mentioned in https://gitter.im/slog-rs/slog that this issue is due to lack of 0.4 support

Issue: slog logs as unknown for record.module() or record.filename() for other crates
e.g 2019-03-09T13:28:08.983|INFO|.43|Stats not enabled
it does print record.line() correctly which is 43 here

This is how I am initializing:

    let log_path = PathBuf::from(log_file);
    let drain = RuntimeFilter::new(drain, level, log_path, log_type, term_log_enabled).fuse();
    let drain = slog_envlogger::new(drain);

    let (drain, async_guard) = slog_async::Async::new(drain)
        .chan_size(2 * 1024 * 1024)
        .overflow_strategy(slog_async::OverflowStrategy::Drop)
        .build_with_guard();
    let drain = drain.fuse();
    let logger = slog::Logger::root(drain, o!());
    (logger, async_guard)

[dpc]

This change as it is right does not look proper (patch.crates-io] etc. is not something we that can be released). Someone has to finish it up.

[rohitjoshi]

@dpc Another issue was that it reduced performance to half when slog_envlogger is used as let _error_logger = slog_envlogger::init().unwrap();

[dpc]

envlogger's performance is quite bad anyway. :D