Module flexi_logger::trc

Available on crate feature trc only.

Use flexi_logger functionality with tracing.

tracing is an alternative to log. It has a similar base architecture, but is optimized for supporting async apps, which adds complexity due to the need to manage contexts. tracing-subscriber facilitates contributing “backends”, and is used in the example below to plug flexi_logger-functionality into tracing.

The content of this module is an attempt to support such an integration. Feedback is highly appreciated.

Example

The following code example uses two features of flexi_logger:

• a fully configurable FileLogWriter as trace writer
• and flexi_logger’s specfile handling to adapt tracing dynamically, while your program is running.

Precondition: add these entries to your Cargo.toml:

flexi_logger = {version = "0.23", features = ["trc"]}
tracing = "0.1"

In this example, the interaction with tracing components is completely hidden, for convenience. If you want to influence tracing further, what might often be the case, you need to copy the code of method setup_tracing into your program and modify it.

Unfortunately, especially due to the use of closures in tracing-subscriber’s API, it is not easy to provide a convenient and flexible API for plugging flexi_logger functionality into tracing.

use flexi_logger::{
    writers::FileLogWriter,
    Age, Cleanup, Criterion, FileSpec, LogSpecification, Naming, WriteMode,
};


// Drop the keep-alive-handles only in the shutdown of your program
let _keep_alive_handles = flexi_logger::trc::setup_tracing(
    LogSpecification::info(),
    Some(&PathBuf::from("trcspecfile.toml")),
    FileLogWriter::builder(FileSpec::default())
        .rotate(
            Criterion::Age(Age::Day),
            Naming::Timestamps,
            Cleanup::KeepLogFiles(7),
        )
        .write_mode(WriteMode::Async),
)?;

tracing::debug!("now we start doing what we really wanted to do...")

Structs

SpecFileNotifier

Rereads the specfile if it was updated and forwards the update to tracing’s filter.

Traits

LogSpecSubscriber

Trait that allows to register for changes to the log specification.

Functions

setup_tracing

Set up tracing to write into the specified FileLogWriter, and to use the (optionally) specified specfile.

subscribe_to_specfile

Allows registering a LogSpecSubscriber to a specfile.