better-tracing = tracing-subscriber + smart defaults and features that just work
See the CHANGELOG for implemented features and fixes.
Utilities for implementing and composing tracing subscribers. This fork provides sensible defaults, accessible formatting, and resolves architectural limitations while maintaining drop-in compatibility.
Backward compatibility and compatibility with 3rd party crates that might use tracing_subscriber will be maintained on a best-effort basis.
| Feature | better-tracing | tracing-subscriber |
|---|---|---|
| Drop-in compatibility | ✅ | ✅ |
| Easier time formats | ✅ | ❌ |
| External formatters access exiting span on EXIT/CLOSE | ✅ | ❌ |
| Sane defaults with zero configuration | ⏳ | ❌ |
| Better builders you don't have to fight with | ⏳ | ❌ |
Compiler support: requires rustc 1.65+
Configure timestamps without extra crates and keep using .with_timer(...):
- RFC 3339 (UTC):
SystemTime::rfc3339_seconds()→YYYY-MM-DDTHH:MM:SSZSystemTime::rfc3339_millis()→YYYY-MM-DDTHH:MM:SS.mmmZSystemTime::rfc3339_nanos()→YYYY-MM-DDTHH:MM:SS.nnnnnnnnnZ
- Unix epoch (UTC):
SystemTime::unix_seconds()/unix_millis()/unix_micros()/unix_nanos()
- Time-only (no date, great for dev logs):
SystemTime::time_only_secs()→HH:MM:SSSystemTime::time_only_millis()→HH:MM:SS.mmmSystemTime::time_only_micros()→HH:MM:SS.uuuuuu
Examples:
use better_tracing::fmt::time::SystemTime;
let subscriber = better_tracing::fmt()
.with_timer(SystemTime::time_only_millis())
.finish();use better_tracing::fmt::time::SystemTime;
let subscriber = better_tracing::fmt()
.with_timer(SystemTime::rfc3339_millis())
.finish();With optional engines, pick the matching helpers: fmt::time::ChronoUtc::* (chrono), fmt::time::UtcTime::* (time), or fmt::time::SystemTime::* (default).
In tracing-subscriber, lookup_current() returned the parent span instead of the exiting span during FmtSpan::EXIT and FmtSpan::CLOSE events. better-tracing fixes this.
use better_tracing::fmt::format::FmtSpan;
// Custom formatter that can now access the exiting span
use better_tracing::{
fmt::{FmtContext, FormatEvent, FormatFields, format::Writer},
registry::LookupSpan,
};
use tracing::{Event, Subscriber};
use std::fmt;
struct MyFormatter;
impl<S, N> FormatEvent<S, N> for MyFormatter
where
S: Subscriber + for<'a> LookupSpan<'a>,
N: for<'a> FormatFields<'a> + 'static,
{
fn format_event(
&self,
ctx: &FmtContext<'_, S, N>,
mut writer: Writer<'_>,
event: &Event<'_>,
) -> fmt::Result {
// Now returns the correct exiting span during EXIT/CLOSE events
if let Some(span) = ctx.lookup_current() {
write!(writer, "{}:", span.name())?;
}
Ok(())
}
}
// Set up subscriber with the custom formatter and EXIT events
let subscriber = better_tracing::fmt()
.with_span_events(FmtSpan::EXIT)
.event_format(MyFormatter)
.finish();tracing is a framework for instrumenting Rust programs to collect
scoped, structured, and async-aware diagnostics. The Subscriber trait
represents the functionality necessary to collect this trace data. This
crate contains tools for composing subscribers out of smaller units of
behaviour, and batteries-included implementations of common subscriber
functionality.
better-tracing is intended for use by both Subscriber authors and
application authors using tracing to instrument their applications.
The most important component of the better-tracing API is the
Layer trait, which provides a composable abstraction for building
Subscribers. Like the Subscriber trait, a Layer defines a
particular behavior for collecting trace data. Unlike Subscribers,
which implement a complete strategy for how trace data is collected,
Layers provide modular implementations of specific behaviors.
Therefore, they can be composed together to form a Subscriber which is
capable of recording traces in a variety of ways. See the layer module's
documentation for details on using Layers.
In addition, the Filter trait defines an interface for filtering what
spans and events are recorded by a particular layer. This allows different
Layers to handle separate subsets of the trace data emitted by a
program. See the documentation on per-layer filtering for more
information on using Filters.
The following Subscribers are provided for application authors:
fmt- Formats and logs tracing data (requires thefmtfeature flag)
std: Enables APIs that depend on the Rust standard library (enabled by default).alloc: Depend onliballoc(enabled by "std").env-filter: Enables theEnvFiltertype, which implements filtering similar to theenv_loggercrate. Requires "std".fmt: Enables thefmtmodule, which provides a subscriber implementation for printing formatted representations of trace events. Enabled by default. Requires "registry" and "std".ansi: Enablesfmtsupport for ANSI terminal colors. Enabled by default.registry: enables theregistrymodule. Enabled by default. Requires "std".json: Enablesfmtsupport for JSON output. In JSON output, the ANSI feature does nothing. Requires "fmt" and "std".local-time: Enables local time formatting when using thetimecrate's timestamp formatters with thefmtsubscriber.
tracing-log: Enables better formatting for events emitted bylogmacros in thefmtsubscriber. Enabled by default.time: Enables support for using thetimecrate for timestamp formatting in thefmtsubscriber.smallvec: Causes theEnvFiltertype to use thesmallveccrate (rather thanVec) as a performance optimization. Enabled by default.parking_lot: Use theparking_lotcrate'sRwLockimplementation rather than the Rust standard library's implementation.
In embedded systems and other bare-metal applications, tracing can be
used without requiring the Rust standard library, although some features are
disabled. Although most of the APIs provided by better-tracing, such
as fmt and EnvFilter, require the standard library, some
functionality, such as the Layer trait, can still be used in
no_std environments.
The dependency on the standard library is controlled by two crate feature
flags, "std", which enables the dependency on libstd, and "alloc", which
enables the dependency on liballoc (and is enabled by the "std"
feature). These features are enabled by default, but no_std users can
disable them using:
# Cargo.toml
better-tracing = { version = "0.3", default-features = false }Additional APIs are available when liballoc is available. To enable
liballoc but not std, use:
# Cargo.toml
better-tracing = { version = "0.3", default-features = false, features = ["alloc"] }These feature flags enable unstable features. The public API may break in 0.1.x
releases. To enable these features, the --cfg tracing_unstable must be passed to
rustc when compiling.
The following unstable feature flags are currently available:
valuable: Enables support for serializing values recorded using thevaluablecrate as structured JSON in theformat::Jsonformatter.
The easiest way to set the tracing_unstable cfg is to use the RUSTFLAGS
env variable when running cargo commands:
RUSTFLAGS="--cfg tracing_unstable" cargo buildAlternatively, the following can be added to the .cargo/config file in a
project to automatically enable the cfg flag for that project:
[build]
rustflags = ["--cfg", "tracing_unstable"]This fork follows the same minimum supported Rust version as the upstream tracing-subscriber.
The minimum supported version is 1.65. The current version is not guaranteed to build on Rust
versions earlier than the minimum supported version.
better-tracing follows a similar compiler support policy to the upstream project. The current stable Rust compiler and the three most recent minor versions before it will always be supported. For example, if the current stable compiler version is 1.69, the minimum supported version will not be increased past 1.66, three minor versions prior. Increasing the minimum supported compiler version is not considered a semver breaking change as long as doing so complies with this policy.
This project is licensed under the MIT license.
This is an independent community fork of tracing-subscriber. This project is not affiliated with, endorsed by, sponsored by, or supported by the Tokio team, the Tokio project, or any of the original tracing-subscriber maintainers. All trademarks are the property of their respective owners.
The name "tracing" and related trademarks belong to their respective owners. This fork exists to provide enhanced functionality while maintaining compatibility with the upstream project.
Unless you explicitly state otherwise, any contributio 5748 n intentionally submitted for inclusion in better-tracing by you, shall be licensed as MIT, without any additional terms or conditions.
License: MIT