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84d5a7f5a0
## Motivation Currently, the primary way to use a span is to use `.enter` and pass a closure to be executed under the span. While that is convenient in many settings, it also comes with two decently inconvenient drawbacks: - It breaks control flow statements like `return`, `?`, `break`, and `continue` - It require re-indenting a potentially large chunk of code if you wish it to appear under a span ## Solution This branch changes the `Span::enter` function to return a scope guard that exits the span when dropped, as in: ```rust let guard = span.enter(); // code here is within the span drop(guard); // code here is no longer within the span ``` The method previously called `enter`, which takes a closure and executes it in the span's context, is now called `Span::in_scope`, and was reimplemented on top of the new `enter` method. This is a breaking change to `tokio-trace` that will be part of the upcoming 0.2 release. Closes #1075 Signed-off-by: Eliza Weisman <eliza@buoyant.io>
54 lines
2.0 KiB
Rust
54 lines
2.0 KiB
Rust
//! A simple example demonstrating how one might implement a custom
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//! subscriber.
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//!
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//! This subscriber implements a tree-structured logger similar to
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//! the "compact" formatter in [`slog-term`]. The demo mimicks the
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//! example output in the screenshot in the [`slog` README].
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//!
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//! Note that this logger isn't ready for actual production use.
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//! Several corners were cut to make the example simple.
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//!
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//! [`slog-term`]: https://docs.rs/slog-term/2.4.0/slog_term/
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//! [`slog` README]: https://github.com/slog-rs/slog#terminal-output-example
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#[macro_use]
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extern crate tokio_trace;
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use tokio_trace::{field, Level};
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mod sloggish_subscriber;
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use self::sloggish_subscriber::SloggishSubscriber;
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fn main() {
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let subscriber = SloggishSubscriber::new(2);
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tokio_trace::subscriber::with_default(subscriber, || {
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span!(Level::TRACE, "", version = &field::display(5.0)).in_scope(|| {
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span!(Level::TRACE, "server", host = "localhost", port = 8080).in_scope(|| {
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info!("starting");
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info!("listening");
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let peer1 = span!(Level::TRACE, "conn", peer_addr = "82.9.9.9", port = 42381);
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peer1.in_scope(|| {
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debug!("connected");
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debug!({ length = 2 }, "message received");
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});
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let peer2 = span!(Level::TRACE, "conn", peer_addr = "8.8.8.8", port = 18230);
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peer2.in_scope(|| {
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debug!("connected");
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});
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peer1.in_scope(|| {
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warn!({ algo = "xor" }, "weak encryption requested");
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debug!({ length = 8 }, "response sent");
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debug!("disconnected");
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});
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peer2.in_scope(|| {
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debug!({ length = 5 }, "message received");
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debug!({ length = 8 }, "response sent");
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debug!("disconnected");
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});
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warn!("internal error");
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info!("exit");
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})
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});
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});
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}
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