How to write logs in one log file when functions are in different modules

[MrCoco5921]

in spdlog/examples/07_async_pool_sink.rs, firstly, we must construct a logger, that is Arc type. Then we use info!(logger: logger, "hello async_pool_sink"); to write this sentence "hello async_pool_sink" into the specific log file. However, I notice that there must be a logger param.

my code is like this:

fn foo(logger: Arc<Logger>) {
    info!(logger:logger,  "foo");
}

fn test(logger: Arc<Logger>) {
    error!(logger:logger, "test");
}

fn main() -> Result<(), spdlog::Error> {
    const LOG_FILE: &str = "tmp/async_file_sink.log";
    let path: PathBuf = env::current_exe().unwrap().parent().unwrap().join(LOG_FILE);
    let file_sink: Arc<FileSink> = Arc::new(FileSink::builder().path(path).truncate(true).build()?);
    let async_pool_sink: Arc<AsyncPoolSink> = Arc::new(AsyncPoolSink::builder().sink(file_sink).build().unwrap());
    let logger: Arc<Logger> = Arc::new(Logger::builder().sink(async_pool_sink).build()?);
    info!(logger:logger, "hello async_pool_sink");
    foo(logger.clone());
    test(logger.clone());
    Ok(())
}

there are two functions foo and test needing to output log, but I don't want to send logger parameter to these functions.
So I want to ask if there is any solution to realize this：

fn foo() { info!(logger:logger, "foo"); }

or

fn foo() { info!("foo"); }

and the logs output into the same log file.
Thanks.

[SpriteOvO]

You can call spdlog::set_default_logger() with the logger you constructed, then just a fn foo() { info!("foo"); } to use your custom logger.

[MrCoco5921]

I try this:

let logger: Arc<Logger> = Arc::new(Logger::builder().sink(async_pool_sink).build()?);
logger.set_flush_level_filter(LevelFilter::All);
set_default_logger(logger);
warn!("hello async_pool_sink");  // also try error!

but file is still empty.

[SpriteOvO]

I reproduced the problem, regarding what's happening here, my guess is that the main function returns and exits before the asynchronous thread receives the log in time after this log is sent to it.

I think this should be considered a bug, and I'll see if it's possible to fix it later. But for now, you can add these two lines to the end of the main function as a workaround.

std::thread::sleep(std::time::Duration::from_millis(100));
spdlog::default_logger().flush();

Thanks for your feedback.

[SpriteOvO]

I created a issue #64 to track the bug.

[MrCoco5921]

Thanks. It works after I add these two line into my code. However, in my work project, I think it is inconvenient that I must add these two lines to see the log, and at the same time, project may throw some exceptions before running these two lines. So I would appreciate it if you could fix this problem.

[SpriteOvO]

Yes, those two lines are definitely expected to be unnecessary, I'll try to fix the bug. On the other hand, if you use FileSink directly instead of wrapping it with AsyncPoolSink, you can avoid encountering this bug as well.

Let me know if you have any other questions :)