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## Motivation PR #934 fixed a bug in the CI configuration where MSRV checks were not being run correctly. After this was fixed, it was necessary to bump the MSRV to 1.40.0, as the tests were no longer actually passing on 1.39, because some dependencies no longer support it. While updating the documentation to indicate that the new MSRV is 1.40, I noticed that the note on the MSRV was located inconsistently in the READMEs and `lib.rs` documentation of various crates, and missing entirely in some cases. Additionally, there have been some questions on what our MSRV _policies_ are, and whether MSRV bumps are considered breaking changes (see e.g. #936). ## Solution I've updated all the MSRV notes in the documentation and READMEs to indicate that the MSRV is 1.40. I've also ensured that the MSRV note is in the same place for every crate (at the end of the "Overview" section in the docs), and that it's formatted consistently. Furthermore, I added a new section to the READMEs and `lib.rs` docs explaining the current MSRV policy in some detail. Hopefully, this should answer questions like #936 in the future. The MSRV note in the overview section includes a link to the section with further details. Finally, while doing this, I noticed a couple of crates (`tracing-journald` and `tracing-serde`) were missing top-level `lib.rs` docs. Rather than just adding an MSRV note and nothing else, I went ahead and fixed this using documentation from those crate's READMEs. Signed-off-by: Eliza Weisman <eliza@buoyant.io>
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tracing-serde
An adapter for serializing tracing types using serde.
Overview
tracing is a framework for instrumenting Rust programs to collect
scoped, structured, and async-aware diagnostics.tracing-serde enables
serializing tracing types using serde.
Traditional logging is based on human-readable text messages.
tracing gives us machine-readable structured diagnostic
information. This lets us interact with diagnostic data
programmatically. With tracing-serde, you can implement a
Subscriber to serialize your tracing types and make use of the
existing ecosystem of serde serializers to talk with distributed
tracing systems.
Serializing diagnostic information allows us to do more with our logged values. For instance, when working with logging data in JSON gives us pretty-print when we're debugging in development and you can emit JSON and tracing data to monitor your services in production.
The tracing crate provides the APIs necessary for instrumenting
libraries and applications to emit trace data.
Compiler support: requires rustc 1.40+
Usage
First, add this to your Cargo.toml:
[dependencies]
tracing = "0.1"
tracing-serde = "0.1"
Next, add this to your crate:
#[macro_use]
extern crate tracing;
extern crate tracing_serde;
use tracing_serde::AsSerde;
Please read the tracing documentation
for more information on how to create trace data.
This crate provides the as_serde function, via the AsSerde trait,
which enables serializing the Attributes, Event, Id, Metadata,
and Record tracing values.
For the full example, please see the examples folder.
Implement a Subscriber to format the serialization of tracing
types how you'd like.
pub struct JsonSubscriber {
next_id: AtomicUsize, // you need to assign span IDs, so you need a counter
}
impl Subscriber for JsonSubscriber {
fn new_span(&self, attrs: &Attributes) -> Id {
let id = self.next_id.fetch_add(1, Ordering::Relaxed);
let id = Id::from_u64(id as u64);
let json = json!({
"new_span": {
"attributes": attrs.as_serde(),
"id": id.as_serde(),
}});
println!("{}", json);
id
}
// ...
}
After you implement your Subscriber, you can use your tracing
subscriber (JsonSubscriber in the above example) to record serialized
trace data.
Supported Rust Versions
Tracing is built against the latest stable release. The minimum supported version is 1.40. The current Tracing version is not guaranteed to build on Rust versions earlier than the minimum supported version.
Tracing follows the same compiler support policies as the rest of the Tokio 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 1.45, the minimum supported version will not be increased past 1.42, 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.
License
This project is licensed under the MIT license.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tokio by you, shall be licensed as MIT, without any additional terms or conditions.