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# 0.3.0 (Oct 22, 2021) This is a breaking release of `tracing-subscriber`. The primary breaking change in this release is the removal of the dependency on the [`chrono` crate], due to [RUSTSEC-2020-0159]. To replace `chrono`, support is added for formatting timestamps using the [`time` crate] instead. In addition, this release includes a number of other breaking API changes, such as adding (limited) support for `#![no_std]` targets, removing previously deprecated APIs, and more. ### Breaking Changes - Removed APIs deprecated in the v0.2.x release series. - Renamed `Layer::new_span` to `Layer::on_new_span` ([#1674]) - Removed `Layer` impl for `Arc<L: Layer<S>>` and `Arc<dyn Layer<S> + ...>` ([#1649]) - Replaced the [`chrono` crate] with the [`time` crate] for timestamp formatting, to resolve [RUSTSEC-2020-0159] ([#1646]) - Removed `json` and `env-filter` from default features. They must now be enabled explictly ([#1647]) - Changed `FormatEvent::format_event` and `FormatFields::format_fields` trait methods to take a `Writer` type, rather than a `&mut dyn fmt::Write` trait object ([#1661]) - Changed the signature of the `MakeWriter` trait by adding a lifetime parameter ([#781]) ### Changed - **layer**: Renamed `Layer::new_span` to `Layer::on_new_span` ([#1674]) - **fmt**: Changed `FormatEvent::format_event` and `FormatFields::format_fields` trait methods to take a `Writer` type, rather than a `&mut dyn fmt::Write` trait object ([#1661]) - **json**, **env-filter**: `json` and `env-filter` feature flags are no longer enabled by default ([#1647]) ### Removed - Removed deprecated `CurrentSpan` type ([#1320]) - **registry**: Removed deprecated `SpanRef::parents` iterator, replaced by `SpanRef::scope` in [#1431] ([#1648)]) - **layer**: Removed deprecated `Context::scope` iterator, replaced by `Context::span_scope` and `Context::event_scope` in [#1431] and [#1434] ([#1648)]) - **layer**: Removed `Layer` impl for `Arc<L: Layer<S>>` and `Arc<dyn Layer<S> + ...>`. These interfere with per-layer filtering. ([#1649]) - **fmt**: Removed deprecated `LayerBuilder` type ([#1673]) - **fmt**: Removed `fmt::Layer::on_event` (renamed to `fmt::Layer::fmt_event`) ([#1673]) - **fmt**, **chrono**: Removed the `chrono` feature flag and APIs for using the [`chrono` crate] for timestamp formatting ([#1646]) ### Added - **fmt**, **time**: `LocalTime` and `UtcTime` types for formatting timestamps using the [`time` crate] ([#1646]) - **fmt**: Added a lifetime parameter to the `MakeWriter` trait, allowing it to return a borrowed writer. This enables implementations of `MakeWriter` for types such as `Mutex<T: io::Write>` and `std::fs::File`. ([#781]) - **env-filter**: Documentation improvements ([#1637]) - Support for some APIs on `#![no_std]` targets, by disabling the `std` feature flag ([#1660]) Thanks to @Folyd and @nmathewson for contributing to this release! [#1320]: https://github.com/tokio-rs/tracing/pull/1320 [#1673]: https://github.com/tokio-rs/tracing/pull/1673 [#1674]: https://github.com/tokio-rs/tracing/pull/1674 [#1646]: https://github.com/tokio-rs/tracing/pull/1646 [#1647]: https://github.com/tokio-rs/tracing/pull/1647 [#1648]: https://github.com/tokio-rs/tracing/pull/1648 [#1649]: https://github.com/tokio-rs/tracing/pull/1649 [#1660]: https://github.com/tokio-rs/tracing/pull/1660 [#1661]: https://github.com/tokio-rs/tracing/pull/1661 [#1431]: https://github.com/tokio-rs/tracing/pull/1431 [#1434]: https://github.com/tokio-rs/tracing/pull/1434 [#781]: https://github.com/tokio-rs/tracing/pull/781 [`chrono` crate]: https://crates.io/crates/chrono [`time` crate]: https://crates.io/crates/time [RUSTSEC-2020-0159]: https://rustsec.org/advisories/RUSTSEC-2020-0159.html Signed-off-by: Eliza Weisman <eliza@buoyant.io>
Tracing Examples
This directory contains a collection of examples that demonstrate the use of the
tracing
ecosystem:
- tracing:
counters
: Implements a very simple metrics system to demonstrate how subscribers can consume field values as typed data.sloggish
: A demoSubscriber
implementation that mimics the output ofslog-term
'sCompact
formatter.
- tracing-attributes:
attrs-basic
: A simple example of the#[instrument]
attribute.attrs-literal-field-names
: Demonstrates using literal field names rather than rust tokens..attrs-args
: An example implementing a simple recursive calculation of Fibonacci numbers, to demonstrate how the#[instrument]
attribute can record function arguments.
- tracing-subscriber:
fmt
: Demonstrates the use of thefmt
module intracing-subscriber
, which provides a subscriber implementation that logs traces to the console.fmt-stderr
: Demonstrates overriding the output stream used by thefmt
subscriber.fmt-custom-field
: Demonstrates overriding how thefmt
subscriber formats fields on spans and events.fmt-custom-event
: Demonstrates overriding how thefmt
subscriber formats events.fmt-multiple-writers.rs
: demonstrates howfmt::Layer
can write to multiple destinations (in this instance, stdout and a file) simultaneously.subscriber-filter
: Demonstrates thetracing-subscriber::filter
module, which provides a layer which adds configurable filtering to a subscriber implementation.tower-load
: Demonstrates how dynamically reloadable filters can be used to debug a server under load in production.journald
: Demonstrates how to usefmt
andjournald
layers to output to both the terminal and the system journal.toggle-layers
: Demonstrates how Layers can be wrapped with anOption
allowing them to be dynamically toggled.
- tracing-futures:
spawny-thing
: Demonstrates the use of the#[instrument]
attribute macro asynchronous functions.tokio-spawny-thing.rs
: Similar tospawny-thingy
, but with the additional demonstration instrumenting concurrent tasks created withtokio::spawn
.futures-proxy-server
: Demonstrates the use oftracing-futures
by implementing a simple proxy server, based on this example fromtokio
.async_fn
: Demonstrates how asynchronous functions can be instrumented.echo
: Demonstrates atracing
-instrumented variant of Tokio'secho
example.
- tracing-flame:
infero-flame
: Demonstrates the use oftracing-flame
to generate a flamegraph from spans.
- tracing-tower:
tower-client
: Demonstrates the use oftracing-tower
to instrument a simpletower
HTTP/1.1 client.tower-server
: Demonstrates the use oftracing-tower
to instrument a simpletower
HTTP/1.1 server.
- tracing-serde:
serde-yak-shave
: Demonstrates the use oftracing-serde
by implementing a subscriber that emits trace output as JSON.
- tracing-log:
hyper-echo
: Demonstrates howtracing-log
can be used to record unstructured logs from dependencies astracing
events, by instrumenting this example fromhyper
, and usingtracing-log
to record logs emitted byhyper
.
- tracing-opentelemetry:
opentelemetry
: Demonstrates howtracing-opentelemetry
can be used to export and visualizetracing
span data.opentelemetry-remote-context
: Demonstrates howtracing-opentelemetry
can be used to extract and inject remote context when traces span multiple systems.