Eliza Weisman d664e50b4d subscriber: remove ref-counting from Layer (#149) ...

## Motivation

As I mentioned in https://github.com/tokio-rs/tracing/pull/136#discussion_r300158248, the
`Layer` trait proposed in #136 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. 

## Solution

Adding a callback that's called on closure to `Layer` required modifying
the `Subscriber` trait to allow indicating when a span closes. 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. This function was added in #153. 

This branch updates `tracing-subscriber::Layer` to use `try_close`. 
Rather than having `clone_span`/`drop_span` callbacks on `Layer`, we
now have a `close` function, which is called when the inner subscriber's
`try_close` returns `true`.

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

2019-07-15 10:57:42 -07:00

..

examples

Update other examples to use set_global_default. (#184)

2019-07-12 15:13:09 -07:00

src

chore: update nursery crates to use path deps on tracing (#101)

2019-06-26 16:42:10 -07:00

Cargo.toml

subscriber: remove ref-counting from Layer (#149)

2019-07-15 10:57:42 -07:00