| //! A procedural macro attribute for instrumenting functions with [`tracing`]. |
| //! |
| //! [`tracing`] is a framework for instrumenting Rust programs to collect |
| //! structured, event-based diagnostic information. This crate provides the |
| //! [`#[instrument]`][instrument] procedural macro attribute. |
| //! |
| //! Note that this macro is also re-exported by the main `tracing` crate. |
| //! |
| //! *Compiler support: [requires `rustc` 1.42+][msrv]* |
| //! |
| //! [msrv]: #supported-rust-versions |
| //! |
| //! ## Usage |
| //! |
| //! First, add this to your `Cargo.toml`: |
| //! |
| //! ```toml |
| //! [dependencies] |
| //! tracing-attributes = "0.1.13" |
| //! ``` |
| //! |
| //! The [`#[instrument]`][instrument] attribute can now be added to a function |
| //! to automatically create and enter `tracing` [span] when that function is |
| //! called. For example: |
| //! |
| //! ``` |
| //! use tracing_attributes::instrument; |
| //! |
| //! #[instrument] |
| //! pub fn my_function(my_arg: usize) { |
| //! // ... |
| //! } |
| //! |
| //! # fn main() {} |
| //! ``` |
| //! |
| //! [`tracing`]: https://crates.io/crates/tracing |
| //! [span]: https://docs.rs/tracing/latest/tracing/span/index.html |
| //! [instrument]: attr.instrument.html |
| //! |
| //! ## Supported Rust Versions |
| //! |
| //! Tracing is built against the latest stable release. The minimum supported |
| //! version is 1.42. The current Tracing version is not guaranteed to build on |
| //! Rust versions earlier than the minimum supported version. |
| //! |
| //! Tracing follows the same compiler support policies as the rest of the Tokio |
| //! project. The current stable Rust compiler and the three most recent minor |
| //! versions before it will always be supported. For example, if the current |
| //! stable compiler version is 1.45, the minimum supported version will not be |
| //! increased past 1.42, three minor versions prior. Increasing the minimum |
| //! supported compiler version is not considered a semver breaking change as |
| //! long as doing so complies with this policy. |
| //! |
| #![doc(html_root_url = "https://docs.rs/tracing-attributes/0.1.13")] |
| #![doc( |
| html_logo_url = "https://raw.githubusercontent.com/tokio-rs/tracing/master/assets/logo-type.png", |
| issue_tracker_base_url = "https://github.com/tokio-rs/tracing/issues/" |
| )] |
| #![cfg_attr(docsrs, deny(broken_intra_doc_links))] |
| #![warn( |
| missing_debug_implementations, |
| missing_docs, |
| rust_2018_idioms, |
| unreachable_pub, |
| bad_style, |
| const_err, |
| dead_code, |
| improper_ctypes, |
| non_shorthand_field_patterns, |
| no_mangle_generic_items, |
| overflowing_literals, |
| path_statements, |
| patterns_in_fns_without_body, |
| private_in_public, |
| unconditional_recursion, |
| unused, |
| unused_allocation, |
| unused_comparisons, |
| unused_parens, |
| while_true |
| )] |
| // TODO: once `tracing` bumps its MSRV to 1.42, remove this allow. |
| #![allow(unused)] |
| extern crate proc_macro; |
| |
| use std::collections::{HashMap, HashSet}; |
| use std::iter; |
| |
| use proc_macro2::TokenStream; |
| use quote::{quote, quote_spanned, ToTokens, TokenStreamExt as _}; |
| use syn::ext::IdentExt as _; |
| use syn::parse::{Parse, ParseStream}; |
| use syn::{ |
| punctuated::Punctuated, spanned::Spanned, AttributeArgs, Block, Expr, ExprCall, FieldPat, |
| FnArg, Ident, Item, ItemFn, Lit, LitInt, LitStr, Meta, MetaList, MetaNameValue, NestedMeta, |
| Pat, PatIdent, PatReference, PatStruct, PatTuple, PatTupleStruct, PatType, Path, Signature, |
| Stmt, Token, |
| }; |
| /// Instruments a function to create and enter a `tracing` [span] every time |
| /// the function is called. |
| /// |
| /// By default, the generated span's [name] will be the name of the function, |
| /// the span's [target] will be the current module path, and the span's [level] |
| /// will be [`INFO`], although these properties can be overridden. Any arguments |
| /// to that function will be recorded as fields using [`fmt::Debug`]. |
| /// |
| /// # Overriding Span Attributes |
| /// |
| /// To change the [name] of the generated span, add a `name` argument to the |
| /// `#[instrument]` macro, followed by an equals sign and a string literal. For |
| /// example: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// |
| /// // The generated span's name will be "my_span" rather than "my_function". |
| /// #[instrument(name = "my_span")] |
| /// pub fn my_function() { |
| /// // ... do something incredibly interesting and important ... |
| /// } |
| /// ``` |
| /// |
| /// To override the [target] of the generated span, add a `target` argument to |
| /// the `#[instrument]` macro, followed by an equals sign and a string literal |
| /// for the new target. The [module path] is still recorded separately. For |
| /// example: |
| /// |
| /// ``` |
| /// pub mod my_module { |
| /// # use tracing_attributes::instrument; |
| /// // The generated span's target will be "my_crate::some_special_target", |
| /// // rather than "my_crate::my_module". |
| /// #[instrument(target = "my_crate::some_special_target")] |
| /// pub fn my_function() { |
| /// // ... all kinds of neat code in here ... |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// Finally, to override the [level] of the generated span, add a `level` |
| /// argument, followed by an equals sign and a string literal with the name of |
| /// the desired level. Level names are not case sensitive. For example: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// // The span's level will be TRACE rather than INFO. |
| /// #[instrument(level = "trace")] |
| /// pub fn my_function() { |
| /// // ... I have written a truly marvelous implementation of this function, |
| /// // which this example is too narrow to contain ... |
| /// } |
| /// ``` |
| /// |
| /// # Skipping Fields |
| /// |
| /// To skip recording one or more arguments to a function or method, pass |
| /// the argument's name inside the `skip()` argument on the `#[instrument]` |
| /// macro. This can be used when an argument to an instrumented function does |
| /// not implement [`fmt::Debug`], or to exclude an argument with a verbose or |
| /// costly `Debug` implementation. Note that: |
| /// |
| /// - multiple argument names can be passed to `skip`. |
| /// - arguments passed to `skip` do _not_ need to implement `fmt::Debug`. |
| /// |
| /// ## Examples |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// // This type doesn't implement `fmt::Debug`! |
| /// struct NonDebug; |
| /// |
| /// // `arg` will be recorded, while `non_debug` will not. |
| /// #[instrument(skip(non_debug))] |
| /// fn my_function(arg: usize, non_debug: NonDebug) { |
| /// // ... |
| /// } |
| /// ``` |
| /// |
| /// Skipping the `self` parameter: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// #[derive(Debug)] |
| /// struct MyType { |
| /// data: Vec<u8>, // Suppose this buffer is often quite long... |
| /// } |
| /// |
| /// impl MyType { |
| /// // Suppose we don't want to print an entire kilobyte of `data` |
| /// // every time this is called... |
| /// #[instrument(skip(self))] |
| /// pub fn my_method(&mut self, an_interesting_argument: usize) { |
| /// // ... do something (hopefully, using all that `data`!) |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// # Adding Fields |
| /// |
| /// Additional fields (key-value pairs with arbitrary data) may be added to the |
| /// generated span using the `fields` argument on the `#[instrument]` macro. Any |
| /// Rust expression can be used as a field value in this manner. These |
| /// expressions will be evaluated at the beginning of the function's body, so |
| /// arguments to the function may be used in these expressions. Field names may |
| /// also be specified *without* values. Doing so will result in an [empty field] |
| /// whose value may be recorded later within the function body. |
| /// |
| /// This supports the same [field syntax] as the `span!` and `event!` macros. |
| /// |
| /// Note that overlap between the names of fields and (non-skipped) arguments |
| /// will result in a compile error. |
| /// |
| /// ## Examples |
| /// |
| /// Adding a new field based on the value of an argument: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// |
| /// // This will record a field named "i" with the value of `i` *and* a field |
| /// // named "next" with the value of `i` + 1. |
| /// #[instrument(fields(next = i + 1))] |
| /// pub fn my_function(i: usize) { |
| /// // ... |
| /// } |
| /// ``` |
| /// |
| /// Recording specific properties of a struct as their own fields: |
| /// |
| /// ``` |
| /// # mod http { |
| /// # pub struct Error; |
| /// # pub struct Response<B> { pub(super) _b: std::marker::PhantomData<B> } |
| /// # pub struct Request<B> { _b: B } |
| /// # impl<B> std::fmt::Debug for Request<B> { |
| /// # fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| /// # f.pad("request") |
| /// # } |
| /// # } |
| /// # impl<B> Request<B> { |
| /// # pub fn uri(&self) -> &str { "fake" } |
| /// # pub fn method(&self) -> &str { "GET" } |
| /// # } |
| /// # } |
| /// # use tracing_attributes::instrument; |
| /// |
| /// // This will record the request's URI and HTTP method as their own separate |
| /// // fields. |
| /// #[instrument(fields(http.uri = req.uri(), http.method = req.method()))] |
| /// pub fn handle_request<B>(req: http::Request<B>) -> http::Response<B> { |
| /// // ... handle the request ... |
| /// # http::Response { _b: std::marker::PhantomData } |
| /// } |
| /// ``` |
| /// |
| /// This can be used in conjunction with `skip` to record only some fields of a |
| /// struct: |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// // Remember the struct with the very large `data` field from the earlier |
| /// // example? Now it also has a `name`, which we might want to include in |
| /// // our span. |
| /// #[derive(Debug)] |
| /// struct MyType { |
| /// name: &'static str, |
| /// data: Vec<u8>, |
| /// } |
| /// |
| /// impl MyType { |
| /// // This will skip the `data` field, but will include `self.name`, |
| /// // formatted using `fmt::Display`. |
| /// #[instrument(skip(self), fields(self.name = %self.name))] |
| /// pub fn my_method(&mut self, an_interesting_argument: usize) { |
| /// // ... do something (hopefully, using all that `data`!) |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// Adding an empty field to be recorded later: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// |
| /// // This function does a very interesting and important mathematical calculation. |
| /// // Suppose we want to record both the inputs to the calculation *and* its result... |
| /// #[instrument(fields(result))] |
| /// pub fn do_calculation(input_1: usize, input_2: usize) -> usize { |
| /// // Rerform the calculation. |
| /// let result = input_1 + input_2; |
| /// |
| /// // Record the result as part of the current span. |
| /// tracing::Span::current().record("result", &result); |
| /// |
| /// // Now, the result will also be included on this event! |
| /// tracing::info!("calculation complete!"); |
| /// |
| /// // ... etc ... |
| /// # 0 |
| /// } |
| /// ``` |
| /// |
| /// # Examples |
| /// |
| /// Instrumenting a function: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// #[instrument] |
| /// pub fn my_function(my_arg: usize) { |
| /// // This event will be recorded inside a span named `my_function` with the |
| /// // field `my_arg`. |
| /// tracing::info!("inside my_function!"); |
| /// // ... |
| /// } |
| /// ``` |
| /// Setting the level for the generated span: |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// #[instrument(level = "debug")] |
| /// pub fn my_function() { |
| /// // ... |
| /// } |
| /// ``` |
| /// Overriding the generated span's name: |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// #[instrument(name = "my_name")] |
| /// pub fn my_function() { |
| /// // ... |
| /// } |
| /// ``` |
| /// Overriding the generated span's target: |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// #[instrument(target = "my_target")] |
| /// pub fn my_function() { |
| /// // ... |
| /// } |
| /// ``` |
| /// |
| /// To skip recording an argument, pass the argument's name to the `skip`: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// struct NonDebug; |
| /// |
| /// #[instrument(skip(non_debug))] |
| /// fn my_function(arg: usize, non_debug: NonDebug) { |
| /// // ... |
| /// } |
| /// ``` |
| /// |
| /// To add an additional context to the span, pass key-value pairs to `fields`: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// #[instrument(fields(foo="bar", id=1, show=true))] |
| /// fn my_function(arg: usize) { |
| /// // ... |
| /// } |
| /// ``` |
| /// |
| /// If the function returns a `Result<T, E>` and `E` implements `std::fmt::Display`, you can add |
| /// `err` to emit error events when the function returns `Err`: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// #[instrument(err)] |
| /// fn my_function(arg: usize) -> Result<(), std::io::Error> { |
| /// Ok(()) |
| /// } |
| /// ``` |
| /// |
| /// `async fn`s may also be instrumented: |
| /// |
| /// ``` |
| /// # use tracing_attributes::instrument; |
| /// #[instrument] |
| /// pub async fn my_function() -> Result<(), ()> { |
| /// // ... |
| /// # Ok(()) |
| /// } |
| /// ``` |
| /// |
| /// It also works with [async-trait](https://crates.io/crates/async-trait) |
| /// (a crate that allows defining async functions in traits, |
| /// something not currently possible in Rust), |
| /// and hopefully most libraries that exhibit similar behaviors: |
| /// |
| /// ``` |
| /// # use tracing::instrument; |
| /// use async_trait::async_trait; |
| /// |
| /// #[async_trait] |
| /// pub trait Foo { |
| /// async fn foo(&self, arg: usize); |
| /// } |
| /// |
| /// #[derive(Debug)] |
| /// struct FooImpl(usize); |
| /// |
| /// #[async_trait] |
| /// impl Foo for FooImpl { |
| /// #[instrument(fields(value = self.0, tmp = std::any::type_name::<Self>()))] |
| /// async fn foo(&self, arg: usize) {} |
| /// } |
| /// ``` |
| /// |
| /// An interesting note on this subject is that references to the `Self` |
| /// type inside the `fields` argument are only allowed when the instrumented |
| /// function is a method aka. the function receives `self` as an argument. |
| /// For example, this *will not work* because it doesn't receive `self`: |
| /// ```compile_fail |
| /// # use tracing::instrument; |
| /// use async_trait::async_trait; |
| /// |
| /// #[async_trait] |
| /// pub trait Bar { |
| /// async fn bar(); |
| /// } |
| /// |
| /// #[derive(Debug)] |
| /// struct BarImpl(usize); |
| /// |
| /// #[async_trait] |
| /// impl Bar for BarImpl { |
| /// #[instrument(fields(tmp = std::any::type_name::<Self>()))] |
| /// async fn bar() {} |
| /// } |
| /// ``` |
| /// Instead, you should manually rewrite any `Self` types as the type for |
| /// which you implement the trait: `#[instrument(fields(tmp = std::any::type_name::<Bar>()))]`. |
| /// |
| /// [span]: https://docs.rs/tracing/latest/tracing/span/index.html |
| /// [name]: https://docs.rs/tracing/latest/tracing/struct.Metadata.html#method.name |
| /// [target]: https://docs.rs/tracing/latest/tracing/struct.Metadata.html#method.target |
| /// [level]: https://docs.rs/tracing/latest/tracing/struct.Level.html |
| /// [module path]: https://docs.rs/tracing/latest/tracing/struct.Metadata.html#method.module_path |
| /// [`INFO`]: https://docs.rs/tracing/latest/tracing/struct.Level.html#associatedconstant.INFO |
| /// [empty field]: https://docs.rs/tracing/latest/tracing/field/struct.Empty.html |
| /// [field syntax]: https://docs.rs/tracing/latest/tracing/#recording-fields |
| /// [`fmt::Debug`]: https://doc.rust-lang.org/std/fmt/trait.Debug.html |
| #[proc_macro_attribute] |
| pub fn instrument( |
| args: proc_macro::TokenStream, |
| item: proc_macro::TokenStream, |
| ) -> proc_macro::TokenStream { |
| let input: ItemFn = syn::parse_macro_input!(item as ItemFn); |
| let args = syn::parse_macro_input!(args as InstrumentArgs); |
| |
| let instrumented_function_name = input.sig.ident.to_string(); |
| |
| // check for async_trait-like patterns in the block and wrap the |
| // internal function with Instrument instead of wrapping the |
| // async_trait generated wrapper |
| if let Some(internal_fun) = get_async_trait_info(&input.block, input.sig.asyncness.is_some()) { |
| // let's rewrite some statements! |
| let mut stmts: Vec<Stmt> = input.block.stmts.to_vec(); |
| for stmt in &mut stmts { |
| if let Stmt::Item(Item::Fn(fun)) = stmt { |
| // instrument the function if we considered it as the one we truly want to trace |
| if fun.sig.ident == internal_fun.name { |
| *stmt = syn::parse2(gen_body( |
| fun, |
| args, |
| instrumented_function_name, |
| Some(internal_fun), |
| )) |
| .unwrap(); |
| break; |
| } |
| } |
| } |
| |
| let vis = &input.vis; |
| let sig = &input.sig; |
| let attrs = &input.attrs; |
| quote!( |
| #(#attrs) * |
| #vis #sig { |
| #(#stmts) * |
| } |
| ) |
| .into() |
| } else { |
| gen_body(&input, args, instrumented_function_name, None).into() |
| } |
| } |
| |
| fn gen_body( |
| input: &ItemFn, |
| mut args: InstrumentArgs, |
| instrumented_function_name: String, |
| async_trait_fun: Option<AsyncTraitInfo>, |
| ) -> proc_macro2::TokenStream { |
| // these are needed ahead of time, as ItemFn contains the function body _and_ |
| // isn't representable inside a quote!/quote_spanned! macro |
| // (Syn's ToTokens isn't implemented for ItemFn) |
| let ItemFn { |
| attrs, |
| vis, |
| block, |
| sig, |
| .. |
| } = input; |
| |
| let Signature { |
| output: return_type, |
| inputs: params, |
| unsafety, |
| asyncness, |
| constness, |
| abi, |
| ident, |
| generics: |
| syn::Generics { |
| params: gen_params, |
| where_clause, |
| .. |
| }, |
| .. |
| } = sig; |
| |
| let err = args.err; |
| let warnings = args.warnings(); |
| |
| // generate the span's name |
| let span_name = args |
| // did the user override the span's name? |
| .name |
| .as_ref() |
| .map(|name| quote!(#name)) |
| .unwrap_or_else(|| quote!(#instrumented_function_name)); |
| |
| // generate this inside a closure, so we can return early on errors. |
| let span = (|| { |
| // Pull out the arguments-to-be-skipped first, so we can filter results |
| // below. |
| let param_names: Vec<(Ident, Ident)> = params |
| .clone() |
| .into_iter() |
| .flat_map(|param| match param { |
| FnArg::Typed(PatType { pat, .. }) => param_names(*pat), |
| FnArg::Receiver(_) => Box::new(iter::once(Ident::new("self", param.span()))), |
| }) |
| // Little dance with new (user-exposed) names and old (internal) |
| // names of identifiers. That way, you can do the following |
| // even though async_trait rewrite "self" as "_self": |
| // ``` |
| // #[async_trait] |
| // impl Foo for FooImpl { |
| // #[instrument(skip(self))] |
| // async fn foo(&self, v: usize) {} |
| // } |
| // ``` |
| .map(|x| { |
| // if we are inside a function generated by async-trait, we |
| // should take care to rewrite "_self" as "self" for |
| // 'user convenience' |
| if async_trait_fun.is_some() && x == "_self" { |
| (Ident::new("self", x.span()), x) |
| } else { |
| (x.clone(), x) |
| } |
| }) |
| .collect(); |
| |
| for skip in &args.skips { |
| if !param_names.iter().map(|(user, _)| user).any(|y| y == skip) { |
| return quote_spanned! {skip.span()=> |
| compile_error!("attempting to skip non-existent parameter") |
| }; |
| } |
| } |
| |
| let level = args.level(); |
| let target = args.target(); |
| |
| // filter out skipped fields |
| let mut quoted_fields: Vec<_> = param_names |
| .into_iter() |
| .filter(|(param, _)| { |
| if args.skips.contains(param) { |
| return false; |
| } |
| |
| // If any parameters have the same name as a custom field, skip |
| // and allow them to be formatted by the custom field. |
| if let Some(ref fields) = args.fields { |
| fields.0.iter().all(|Field { ref name, .. }| { |
| let first = name.first(); |
| first != name.last() || !first.iter().any(|name| name == ¶m) |
| }) |
| } else { |
| true |
| } |
| }) |
| .map(|(user_name, real_name)| quote!(#user_name = tracing::field::debug(&#real_name))) |
| .collect(); |
| |
| // when async-trait is in use, replace instances of "self" with "_self" inside the fields values |
| if let (Some(ref async_trait_fun), Some(Fields(ref mut fields))) = |
| (async_trait_fun, &mut args.fields) |
| { |
| let mut replacer = SelfReplacer { |
| ty: async_trait_fun.self_type.clone(), |
| }; |
| for e in fields.iter_mut().filter_map(|f| f.value.as_mut()) { |
| syn::visit_mut::visit_expr_mut(&mut replacer, e); |
| } |
| } |
| |
| let custom_fields = &args.fields; |
| |
| quote!(tracing::span!( |
| target: #target, |
| #level, |
| #span_name, |
| #(#quoted_fields,)* |
| #custom_fields |
| |
| )) |
| })(); |
| |
| // Generate the instrumented function body. |
| // If the function is an `async fn`, this will wrap it in an async block, |
| // which is `instrument`ed using `tracing-futures`. Otherwise, this will |
| // enter the span and then perform the rest of the body. |
| // If `err` is in args, instrument any resulting `Err`s. |
| let body = if asyncness.is_some() { |
| if err { |
| quote_spanned! {block.span()=> |
| let __tracing_attr_span = #span; |
| tracing::Instrument::instrument(async move { |
| match async move { #block }.await { |
| #[allow(clippy::unit_arg)] |
| Ok(x) => Ok(x), |
| Err(e) => { |
| tracing::error!(error = %e); |
| Err(e) |
| } |
| } |
| }, __tracing_attr_span).await |
| } |
| } else { |
| quote_spanned!(block.span()=> |
| let __tracing_attr_span = #span; |
| tracing::Instrument::instrument( |
| async move { #block }, |
| __tracing_attr_span |
| ) |
| .await |
| ) |
| } |
| } else if err { |
| quote_spanned!(block.span()=> |
| let __tracing_attr_span = #span; |
| let __tracing_attr_guard = __tracing_attr_span.enter(); |
| #[allow(clippy::redundant_closure_call)] |
| match (move || #block)() { |
| #[allow(clippy::unit_arg)] |
| Ok(x) => Ok(x), |
| Err(e) => { |
| tracing::error!(error = %e); |
| Err(e) |
| } |
| } |
| ) |
| } else { |
| quote_spanned!(block.span()=> |
| let __tracing_attr_span = #span; |
| let __tracing_attr_guard = __tracing_attr_span.enter(); |
| #block |
| ) |
| }; |
| |
| quote!( |
| #(#attrs) * |
| #vis #constness #unsafety #asyncness #abi fn #ident<#gen_params>(#params) #return_type |
| #where_clause |
| { |
| #warnings |
| #body |
| } |
| ) |
| } |
| |
| #[derive(Default, Debug)] |
| struct InstrumentArgs { |
| level: Option<Level>, |
| name: Option<LitStr>, |
| target: Option<LitStr>, |
| skips: HashSet<Ident>, |
| fields: Option<Fields>, |
| err: bool, |
| /// Errors describing any unrecognized parse inputs that we skipped. |
| parse_warnings: Vec<syn::Error>, |
| } |
| |
| impl InstrumentArgs { |
| fn level(&self) -> impl ToTokens { |
| fn is_level(lit: &LitInt, expected: u64) -> bool { |
| match lit.base10_parse::<u64>() { |
| Ok(value) => value == expected, |
| Err(_) => false, |
| } |
| } |
| |
| match &self.level { |
| Some(Level::Str(ref lit)) if lit.value().eq_ignore_ascii_case("trace") => { |
| quote!(tracing::Level::TRACE) |
| } |
| Some(Level::Str(ref lit)) if lit.value().eq_ignore_ascii_case("debug") => { |
| quote!(tracing::Level::DEBUG) |
| } |
| Some(Level::Str(ref lit)) if lit.value().eq_ignore_ascii_case("info") => { |
| quote!(tracing::Level::INFO) |
| } |
| Some(Level::Str(ref lit)) if lit.value().eq_ignore_ascii_case("warn") => { |
| quote!(tracing::Level::WARN) |
| } |
| Some(Level::Str(ref lit)) if lit.value().eq_ignore_ascii_case("error") => { |
| quote!(tracing::Level::ERROR) |
| } |
| Some(Level::Int(ref lit)) if is_level(lit, 1) => quote!(tracing::Level::TRACE), |
| Some(Level::Int(ref lit)) if is_level(lit, 2) => quote!(tracing::Level::DEBUG), |
| Some(Level::Int(ref lit)) if is_level(lit, 3) => quote!(tracing::Level::INFO), |
| Some(Level::Int(ref lit)) if is_level(lit, 4) => quote!(tracing::Level::WARN), |
| Some(Level::Int(ref lit)) if is_level(lit, 5) => quote!(tracing::Level::ERROR), |
| Some(Level::Path(ref pat)) => quote!(#pat), |
| Some(lit) => quote! { |
| compile_error!( |
| "unknown verbosity level, expected one of \"trace\", \ |
| \"debug\", \"info\", \"warn\", or \"error\", or a number 1-5" |
| ) |
| }, |
| None => quote!(tracing::Level::INFO), |
| } |
| } |
| |
| fn target(&self) -> impl ToTokens { |
| if let Some(ref target) = self.target { |
| quote!(#target) |
| } else { |
| quote!(module_path!()) |
| } |
| } |
| |
| /// Generate "deprecation" warnings for any unrecognized attribute inputs |
| /// that we skipped. |
| /// |
| /// For backwards compatibility, we need to emit compiler warnings rather |
| /// than errors for unrecognized inputs. Generating a fake deprecation is |
| /// the only way to do this on stable Rust right now. |
| fn warnings(&self) -> impl ToTokens { |
| let warnings = self.parse_warnings.iter().map(|err| { |
| let msg = format!("found unrecognized input, {}", err); |
| let msg = LitStr::new(&msg, err.span()); |
| // TODO(eliza): This is a bit of a hack, but it's just about the |
| // only way to emit warnings from a proc macro on stable Rust. |
| // Eventually, when the `proc_macro::Diagnostic` API stabilizes, we |
| // should definitely use that instead. |
| quote_spanned! {err.span()=> |
| #[warn(deprecated)] |
| { |
| #[deprecated(since = "not actually deprecated", note = #msg)] |
| const TRACING_INSTRUMENT_WARNING: () = (); |
| let _ = TRACING_INSTRUMENT_WARNING; |
| } |
| } |
| }); |
| quote! { |
| { #(#warnings)* } |
| } |
| } |
| } |
| |
| impl Parse for InstrumentArgs { |
| fn parse(input: ParseStream<'_>) -> syn::Result<Self> { |
| let mut args = Self::default(); |
| while !input.is_empty() { |
| let lookahead = input.lookahead1(); |
| if lookahead.peek(kw::name) { |
| if args.name.is_some() { |
| return Err(input.error("expected only a single `name` argument")); |
| } |
| let name = input.parse::<StrArg<kw::name>>()?.value; |
| args.name = Some(name); |
| } else if lookahead.peek(LitStr) { |
| // XXX: apparently we support names as either named args with an |
| // sign, _or_ as unnamed string literals. That's weird, but |
| // changing it is apparently breaking. |
| if args.name.is_some() { |
| return Err(input.error("expected only a single `name` argument")); |
| } |
| args.name = Some(input.parse()?); |
| } else if lookahead.peek(kw::target) { |
| if args.target.is_some() { |
| return Err(input.error("expected only a single `target` argument")); |
| } |
| let target = input.parse::<StrArg<kw::target>>()?.value; |
| args.target = Some(target); |
| } else if lookahead.peek(kw::level) { |
| if args.level.is_some() { |
| return Err(input.error("expected only a single `level` argument")); |
| } |
| args.level = Some(input.parse()?); |
| } else if lookahead.peek(kw::skip) { |
| if !args.skips.is_empty() { |
| return Err(input.error("expected only a single `skip` argument")); |
| } |
| let Skips(skips) = input.parse()?; |
| args.skips = skips; |
| } else if lookahead.peek(kw::fields) { |
| if args.fields.is_some() { |
| return Err(input.error("expected only a single `fields` argument")); |
| } |
| args.fields = Some(input.parse()?); |
| } else if lookahead.peek(kw::err) { |
| let _ = input.parse::<kw::err>()?; |
| args.err = true; |
| } else if lookahead.peek(Token![,]) { |
| let _ = input.parse::<Token![,]>()?; |
| } else { |
| // We found a token that we didn't expect! |
| // We want to emit warnings for these, rather than errors, so |
| // we'll add it to the list of unrecognized inputs we've seen so |
| // far and keep going. |
| args.parse_warnings.push(lookahead.error()); |
| // Parse the unrecognized token tree to advance the parse |
| // stream, and throw it away so we can keep parsing. |
| let _ = input.parse::<proc_macro2::TokenTree>(); |
| } |
| } |
| Ok(args) |
| } |
| } |
| |
| struct StrArg<T> { |
| value: LitStr, |
| _p: std::marker::PhantomData<T>, |
| } |
| |
| impl<T: Parse> Parse for StrArg<T> { |
| fn parse(input: ParseStream<'_>) -> syn::Result<Self> { |
| let _ = input.parse::<T>()?; |
| let _ = input.parse::<Token![=]>()?; |
| let value = input.parse()?; |
| Ok(Self { |
| value, |
| _p: std::marker::PhantomData, |
| }) |
| } |
| } |
| |
| struct Skips(HashSet<Ident>); |
| |
| impl Parse for Skips { |
| fn parse(input: ParseStream<'_>) -> syn::Result<Self> { |
| let _ = input.parse::<kw::skip>(); |
| let content; |
| let _ = syn::parenthesized!(content in input); |
| let names: Punctuated<Ident, Token![,]> = content.parse_terminated(Ident::parse_any)?; |
| let mut skips = HashSet::new(); |
| for name in names { |
| if skips.contains(&name) { |
| return Err(syn::Error::new( |
| name.span(), |
| "tried to skip the same field twice", |
| )); |
| } else { |
| skips.insert(name); |
| } |
| } |
| Ok(Self(skips)) |
| } |
| } |
| |
| #[derive(Debug)] |
| struct Fields(Punctuated<Field, Token![,]>); |
| |
| #[derive(Debug)] |
| struct Field { |
| name: Punctuated<Ident, Token![.]>, |
| value: Option<Expr>, |
| kind: FieldKind, |
| } |
| |
| #[derive(Debug, Eq, PartialEq)] |
| enum FieldKind { |
| Debug, |
| Display, |
| Value, |
| } |
| |
| impl Parse for Fields { |
| fn parse(input: ParseStream<'_>) -> syn::Result<Self> { |
| let _ = input.parse::<kw::fields>(); |
| let content; |
| let _ = syn::parenthesized!(content in input); |
| let fields: Punctuated<_, Token![,]> = content.parse_terminated(Field::parse)?; |
| Ok(Self(fields)) |
| } |
| } |
| |
| impl ToTokens for Fields { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| self.0.to_tokens(tokens) |
| } |
| } |
| |
| impl Parse for Field { |
| fn parse(input: ParseStream<'_>) -> syn::Result<Self> { |
| let mut kind = FieldKind::Value; |
| if input.peek(Token![%]) { |
| input.parse::<Token![%]>()?; |
| kind = FieldKind::Display; |
| } else if input.peek(Token![?]) { |
| input.parse::<Token![?]>()?; |
| kind = FieldKind::Debug; |
| }; |
| let name = Punctuated::parse_separated_nonempty_with(input, Ident::parse_any)?; |
| let value = if input.peek(Token![=]) { |
| input.parse::<Token![=]>()?; |
| if input.peek(Token![%]) { |
| input.parse::<Token![%]>()?; |
| kind = FieldKind::Display; |
| } else if input.peek(Token![?]) { |
| input.parse::<Token![?]>()?; |
| kind = FieldKind::Debug; |
| }; |
| Some(input.parse()?) |
| } else { |
| None |
| }; |
| Ok(Self { name, kind, value }) |
| } |
| } |
| |
| impl ToTokens for Field { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| if let Some(ref value) = self.value { |
| let name = &self.name; |
| let kind = &self.kind; |
| tokens.extend(quote! { |
| #name = #kind#value |
| }) |
| } else if self.kind == FieldKind::Value { |
| // XXX(eliza): I don't like that fields without values produce |
| // empty fields rather than local variable shorthand...but, |
| // we've released a version where field names without values in |
| // `instrument` produce empty field values, so changing it now |
| // is a breaking change. agh. |
| let name = &self.name; |
| tokens.extend(quote!(#name = tracing::field::Empty)) |
| } else { |
| self.kind.to_tokens(tokens); |
| self.name.to_tokens(tokens); |
| } |
| } |
| } |
| |
| impl ToTokens for FieldKind { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| match self { |
| FieldKind::Debug => tokens.extend(quote! { ? }), |
| FieldKind::Display => tokens.extend(quote! { % }), |
| _ => {} |
| } |
| } |
| } |
| |
| #[derive(Debug)] |
| enum Level { |
| Str(LitStr), |
| Int(LitInt), |
| Path(Path), |
| } |
| |
| impl Parse for Level { |
| fn parse(input: ParseStream<'_>) -> syn::Result<Self> { |
| let _ = input.parse::<kw::level>()?; |
| let _ = input.parse::<Token![=]>()?; |
| let lookahead = input.lookahead1(); |
| if lookahead.peek(LitStr) { |
| Ok(Self::Str(input.parse()?)) |
| } else if lookahead.peek(LitInt) { |
| Ok(Self::Int(input.parse()?)) |
| } else if lookahead.peek(Ident) { |
| Ok(Self::Path(input.parse()?)) |
| } else { |
| Err(lookahead.error()) |
| } |
| } |
| } |
| |
| fn param_names(pat: Pat) -> Box<dyn Iterator<Item = Ident>> { |
| match pat { |
| Pat::Ident(PatIdent { ident, .. }) => Box::new(iter::once(ident)), |
| Pat::Reference(PatReference { pat, .. }) => param_names(*pat), |
| Pat::Struct(PatStruct { fields, .. }) => Box::new( |
| fields |
| .into_iter() |
| .flat_map(|FieldPat { pat, .. }| param_names(*pat)), |
| ), |
| Pat::Tuple(PatTuple { elems, .. }) => Box::new(elems.into_iter().flat_map(param_names)), |
| Pat::TupleStruct(PatTupleStruct { |
| pat: PatTuple { elems, .. }, |
| .. |
| }) => Box::new(elems.into_iter().flat_map(param_names)), |
| |
| // The above *should* cover all cases of irrefutable patterns, |
| // but we purposefully don't do any funny business here |
| // (such as panicking) because that would obscure rustc's |
| // much more informative error message. |
| _ => Box::new(iter::empty()), |
| } |
| } |
| |
| mod kw { |
| syn::custom_keyword!(fields); |
| syn::custom_keyword!(skip); |
| syn::custom_keyword!(level); |
| syn::custom_keyword!(target); |
| syn::custom_keyword!(name); |
| syn::custom_keyword!(err); |
| } |
| |
| // Get the AST of the inner function we need to hook, if it was generated |
| // by async-trait. |
| // When we are given a function annotated by async-trait, that function |
| // is only a placeholder that returns a pinned future containing the |
| // user logic, and it is that pinned future that needs to be instrumented. |
| // Were we to instrument its parent, we would only collect information |
| // regarding the allocation of that future, and not its own span of execution. |
| // So we inspect the block of the function to find if it matches the pattern |
| // `async fn foo<...>(...) {...}; Box::pin(foo<...>(...))` and we return |
| // the name `foo` if that is the case. 'gen_body' will then be able |
| // to use that information to instrument the proper function. |
| // (this follows the approach suggested in |
| // https://github.com/dtolnay/async-trait/issues/45#issuecomment-571245673) |
| fn get_async_trait_function(block: &Block, block_is_async: bool) -> Option<&ItemFn> { |
| // are we in an async context? If yes, this isn't a async_trait-like pattern |
| if block_is_async { |
| return None; |
| } |
| |
| // list of async functions declared inside the block |
| let mut inside_funs = Vec::new(); |
| // last expression declared in the block (it determines the return |
| // value of the block, so that if we are working on a function |
| // whose `trait` or `impl` declaration is annotated by async_trait, |
| // this is quite likely the point where the future is pinned) |
| let mut last_expr = None; |
| |
| // obtain the list of direct internal functions and the last |
| // expression of the block |
| for stmt in &block.stmts { |
| if let Stmt::Item(Item::Fn(fun)) = &stmt { |
| // is the function declared as async? If so, this is a good |
| // candidate, let's keep it in hand |
| if fun.sig.asyncness.is_some() { |
| inside_funs.push(fun); |
| } |
| } else if let Stmt::Expr(e) = &stmt { |
| last_expr = Some(e); |
| } |
| } |
| |
| // let's play with (too much) pattern matching |
| // is the last expression a function call? |
| if let Some(Expr::Call(ExprCall { |
| func: outside_func, |
| args: outside_args, |
| .. |
| })) = last_expr |
| { |
| if let Expr::Path(path) = outside_func.as_ref() { |
| // is it a call to `Box::pin()`? |
| if "Box::pin" == path_to_string(&path.path) { |
| // does it takes at least an argument? (if it doesn't, |
| // it's not gonna compile anyway, but that's no reason |
| // to (try to) perform an out of bounds access) |
| if outside_args.is_empty() { |
| return None; |
| } |
| // is the argument to Box::pin a function call itself? |
| if let Expr::Call(ExprCall { func, args, .. }) = &outside_args[0] { |
| if let Expr::Path(inside_path) = func.as_ref() { |
| // "stringify" the path of the function called |
| let func_name = path_to_string(&inside_path.path); |
| // is this function directly defined insided the current block? |
| for fun in inside_funs { |
| if fun.sig.ident == func_name { |
| // we must hook this function now |
| return Some(fun); |
| } |
| } |
| } |
| } |
| } |
| } |
| } |
| None |
| } |
| |
| struct AsyncTraitInfo { |
| name: String, |
| self_type: Option<syn::TypePath>, |
| } |
| |
| // Return the informations necessary to process a function annotated with async-trait. |
| fn get_async_trait_info(block: &Block, block_is_async: bool) -> Option<AsyncTraitInfo> { |
| let fun = get_async_trait_function(block, block_is_async)?; |
| |
| // if "_self" is present as an argument, we store its type to be able to rewrite "Self" (the |
| // parameter type) with the type of "_self" |
| let self_type = fun |
| .sig |
| .inputs |
| .iter() |
| .map(|arg| { |
| if let FnArg::Typed(ty) = arg { |
| if let Pat::Ident(PatIdent { ident, .. }) = &*ty.pat { |
| if ident == "_self" { |
| let mut ty = &*ty.ty; |
| // extract the inner type if the argument is "&self" or "&mut self" |
| if let syn::Type::Reference(syn::TypeReference { elem, .. }) = ty { |
| ty = &*elem; |
| } |
| if let syn::Type::Path(tp) = ty { |
| return Some(tp.clone()); |
| } |
| } |
| } |
| } |
| |
| None |
| }) |
| .next(); |
| let self_type = match self_type { |
| Some(x) => x, |
| None => None, |
| }; |
| |
| Some(AsyncTraitInfo { |
| name: fun.sig.ident.to_string(), |
| self_type, |
| }) |
| } |
| |
| // Return a path as a String |
| fn path_to_string(path: &Path) -> String { |
| use std::fmt::Write; |
| // some heuristic to prevent too many allocations |
| let mut res = String::with_capacity(path.segments.len() * 5); |
| for i in 0..path.segments.len() { |
| write!(&mut res, "{}", path.segments[i].ident) |
| .expect("writing to a String should never fail"); |
| if i < path.segments.len() - 1 { |
| res.push_str("::"); |
| } |
| } |
| res |
| } |
| |
| // A visitor struct replacing the "self" and "Self" tokens in user-supplied fields expressions when |
| // the function is generated by async-trait. |
| struct SelfReplacer { |
| ty: Option<syn::TypePath>, |
| } |
| |
| impl syn::visit_mut::VisitMut for SelfReplacer { |
| fn visit_ident_mut(&mut self, id: &mut Ident) { |
| if id == "self" { |
| *id = Ident::new("_self", id.span()) |
| } |
| } |
| |
| fn visit_type_mut(&mut self, ty: &mut syn::Type) { |
| if let syn::Type::Path(syn::TypePath { ref mut path, .. }) = ty { |
| if path_to_string(path) == "Self" { |
| if let Some(ref true_type) = self.ty { |
| *path = true_type.path.clone(); |
| } |
| } |
| } |
| } |
| } |
