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https://github.com/tokio-rs/tracing.git
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d9f7858185
## Motivation In order to re-export the `#[instrument]` attribute macro in `tracing`, it must be released to crates.io. There are some changes that needed to be made prior to releasing the procedural macro crate. ## Solution This branch makes the following changes: - Rename the attribute macro from `trace` to `instrument` (see #246) - Add support for setting a verbosity level (see #250) - Add support for setting a target - Rename the `tracing-proc-macros` crate to `tracing-attributes` - Add documentation + a README - Update Cargo.toml metadata The crate should now be ready to publish and re-export from `tracing`. Fixes: #246 Fixes: #250 Refs: #245 Signed-off-by: Eliza Weisman <eliza@buoyant.io>
59 lines
1.7 KiB
Rust
59 lines
1.7 KiB
Rust
//! Demonstrates using the `trace` attribute macro to instrument `async`
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//! functions.
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//!
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//! This is based on the [`hello_world`] example from `tokio`. and implements a
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//! simple client that opens a TCP stream, writes "hello world\n", and closes
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//! the connection.
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//!
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//! You can test this out by running:
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//!
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//! ncat -l 6142
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//!
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//! And then in another terminal run:
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//!
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//! cargo +nightly run --example async_fn
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//!
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//! [`hello_world`]: https://github.com/tokio-rs/tokio/blob/132e9f1da5965530b63554d7a1c59824c3de4e30/tokio/examples/hello_world.rs
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#![feature(async_await)]
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use tokio;
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use tokio::io::AsyncWriteExt;
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use tokio::net::TcpStream;
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use tracing::info;
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use tracing_attributes::instrument;
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use std::{io, error::Error, net::SocketAddr};
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#[instrument]
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async fn connect(addr: &SocketAddr) -> io::Result<TcpStream> {
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let stream = TcpStream::connect(&addr).await;
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tracing::info!("created stream");
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stream
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}
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#[instrument]
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async fn write(stream: &mut TcpStream) -> io::Result<usize> {
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let result = stream.write(b"hello world\n").await;
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info!("wrote to stream; success={:?}", result.is_ok());
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result
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}
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#[tokio::main]
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pub async fn main() -> Result<(), Box<dyn Error>> {
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let addr = "127.0.0.1:6142".parse()?;
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let subscriber = tracing_fmt::FmtSubscriber::builder()
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.with_filter(tracing_fmt::filter::EnvFilter::from("async_fn=trace"))
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.finish();
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tracing::subscriber::set_global_default(subscriber).unwrap();
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// Open a TCP stream to the socket address.
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//
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// Note that this is the Tokio TcpStream, which is fully async.
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let mut stream = connect(&addr).await?;
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write(&mut stream).await?;
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Ok(())
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}
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