bdbaf80073It is not uncommon that users who are new to tracing look at the examples in the `master` branch of the repository and find that they don't compile. This is because they are examples which compile with the code from the master branch, which is for the as yet unreleased tracing 0.2.0 ecosystem. Users should instead go to the `v0.1.x` branch to find examples compatible with the crates published on crates.io. This change adds a doc-comment to the beginning of every example file informing the user of this fact and suggesting that they check out the `v0.1.x` branch instead.
57 lines
2.1 KiB
Rust
57 lines
2.1 KiB
Rust
//! NOTE: This is pre-release documentation for the upcoming tracing 0.2.0 ecosystem. For the
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//! release examples, please see the `v0.1.x` branch instead.
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//!
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//! This example demonstrates that a custom panic hook can be used to log panic
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//! messages even when panics are captured (such as when a Tokio task panics).
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//!
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//! This is essentially the same as the `panic_hook.rs` example, but modified to
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//! spawn async tasks using the Tokio runtime rather than panicking in a
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//! synchronous function. See the `panic_hook.rs` example for details on using
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//! custom panic hooks.
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#[tokio::main]
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async fn main() {
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let collector = tracing_subscriber::fmt()
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.with_max_level(tracing::Level::TRACE)
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.finish();
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// NOTE: Using `tracing` in a panic hook requires the use of the *global*
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// trace dispatcher (`tracing::collect::set_global_default`), rather than
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// the per-thread scoped dispatcher
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// (`tracing::collect::with_default`/`set_default`). With the scoped trace
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// dispatcher, the collector's thread-local context may already have been
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// torn down by unwinding by the time the panic handler is reached.
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tracing::collect::set_global_default(collector).unwrap();
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std::panic::set_hook(Box::new(|panic| {
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if let Some(location) = panic.location() {
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tracing::error!(
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message = %panic,
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panic.file = location.file(),
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panic.line = location.line(),
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panic.column = location.column(),
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);
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} else {
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tracing::error!(message = %panic);
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}
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}));
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// Spawn tasks to check the numbers from 1-10.
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let tasks = (0..10)
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.map(|i| tokio::spawn(check_number(i)))
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.collect::<Vec<_>>();
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futures::future::join_all(tasks).await;
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tracing::trace!("all tasks done");
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}
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#[tracing::instrument]
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async fn check_number(x: i32) {
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tracing::trace!("checking number...");
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tokio::task::yield_now().await;
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if x % 2 == 0 {
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panic!("I don't work with even numbers!");
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}
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tracing::info!("number checks out!")
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}
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