mirror of
https://github.com/tokio-rs/tracing.git
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b385da6b02
## Feature Request ### Crates - `tracing-subscriber` ### Motivation Currently, the `tracing-subscriber` `FmtSubscriber::default` implementation defaults to no filtering. This means that all instrumentation, including extremely verbose `trace`-level diagnostics from crates like `tokio` are enabled by default. This is because the subscriber itself does not implement filtering, in order to allow it to be composed with filters implemented by `Layer`s. However, defaulting to no filtering at all is definitely a surprising behavior. I didn't want to conditionally return a different type based on whether or not filtering was enabled by the `filter` feature flag, but this is probably not worth the confusion introduced by this behavior. We should make this more intuitive. ## Solution This branch changes `tracing-subscriber` to default to enabling the `INFO` level and above. If the `filter` feature flag is enabled, users may opt-in to `env_logger`-style filtering. Additionally, regardless of feature flags, a new `with_max_level` method is added to the `FmtSubscriber` builder, which takes a `Level` or `LevelFilter`. `LevelFilter` now implements `Layer` by enabling any spans and events that are less than or equal to that `Level`. Fixes: #331 Fixes: #332 Signed-off-by: Eliza Weisman <eliza@buoyant.io>
48 lines
1.1 KiB
Rust
48 lines
1.1 KiB
Rust
#![deny(rust_2018_idioms)]
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/// This is a example showing how information is scoped.
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///
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/// You can run this example by running the following command in a terminal
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///
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/// ```
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/// cargo +nightly run --example spawny_thing
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/// ```
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use tokio;
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use futures::future::join_all;
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use tracing::{debug, info};
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use tracing_attributes::instrument;
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#[instrument]
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async fn parent_task(subtasks: usize) {
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info!("spawning subtasks...");
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let subtasks = (1..=subtasks)
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.map(|number| {
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debug!(message = "creating subtask;", number);
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subtask(number)
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})
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.collect::<Vec<_>>();
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let result = join_all(subtasks).await;
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debug!("all subtasks completed");
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let sum: usize = result.into_iter().sum();
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info!(sum);
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}
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#[instrument]
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async fn subtask(number: usize) -> usize {
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info!("polling subtask...");
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number
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}
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#[tokio::main]
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async fn main() -> Result<(), Box<dyn std::error::Error>> {
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let subscriber = tracing_subscriber::fmt::Subscriber::builder()
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.with_max_level(tracing::Level::DEBUG)
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.finish();
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tracing::subscriber::set_global_default(subscriber)?;
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parent_task(10).await;
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Ok(())
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}
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