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History

core: add Subscriber::try_close (#153 )

## Motivation

As discussed in #136, a proposed `Layer` trait for composing subscribers
required should probably _not_ be responsible for managing ref-counts
and determining span closures. Instead, the root subscriber should be
responsible for this, and `Layer`s should be able to opt into a callback
that's notified _when_ a span is closed. 

Adding a callback that's called on closure to `Layer` requires modifying
the `Subscriber` trait to allow indicating when a span closes.

## Solution

This branch attempts to do this without a breaking change, by adding a
new `try_close` trait method to `Subscriber`. `try_close` is identical
to `drop_span` except that it returns a boolean value, set to `true` if
the span has closed. 

The `try_close` default implementation simply calls
`self.drop_span(...)` and returns `false`, so that if subscribers don't
care about tracking ref counts, close notifications will never be
triggered. 

The `drop_span` documentation now indicates that it is "soft deprecated"
similarly to `std::error::Error`'s `description` method. This encourages
subscribers to implement the new API, but isn't a breaking change.
Existing _callers_ of `drop_span` are still able to call it without
causing issues. A subsequent PR will mark `drop_span` as deprecated
in favour of `try_close`.

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

2019-07-09 12:39:47 -07:00

src

core: add Subscriber::try_close (#153 )

2019-07-09 12:39:47 -07:00

tests

Fix typos. (#128 )

2019-07-01 10:14:14 -07:00

Cargo.toml

core: prepare for 0.1.1 (#155 )

2019-07-06 11:18:03 -07:00

CHANGELOG.md

core: prepare for 0.1.1 (#155 )

2019-07-06 11:18:03 -07:00

LICENSE

meta: rename everything to tracing (#99 )

2019-06-26 11:31:07 -07:00

README.md

core: prepare for 0.1.1 (#155 )

2019-07-06 11:18:03 -07:00

README.md

tracing-core

Core primitives for application-level tracing.

Documentation | Chat

Overview

tracing is a framework for instrumenting Rust programs to collect structured, event-based diagnostic information. This crate defines the core primitives of tracing.

The crate provides:

Span identifies a span within the execution of a program.
Event represents a single event within a trace.
Subscriber, the trait implemented to collect trace data.
Metadata and Callsite provide information describing Spans.
Field, FieldSet, Value, and ValueSet represent the structured data attached to a Span.
Dispatch allows span events to be dispatched to Subscribers.

In addition, it defines the global callsite registry and per-thread current dispatcher which other components of the tracing system rely on.

Application authors will typically not use this crate directly. Instead, they will use the tracing crate, which provides a much more fully-featured API. However, this crate's API will change very infrequently, so it may be used when dependencies must be very stable.

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.