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Diffstat (limited to 'vendor/tracing-subscriber-0.3.3/src/fmt/mod.rs')
| -rw-r--r-- | vendor/tracing-subscriber-0.3.3/src/fmt/mod.rs | 1275 |
1 files changed, 1275 insertions, 0 deletions
diff --git a/vendor/tracing-subscriber-0.3.3/src/fmt/mod.rs b/vendor/tracing-subscriber-0.3.3/src/fmt/mod.rs new file mode 100644 index 000000000..d5deb8f0c --- /dev/null +++ b/vendor/tracing-subscriber-0.3.3/src/fmt/mod.rs @@ -0,0 +1,1275 @@ +//! A `Subscriber` for formatting and logging `tracing` data. +//! +//! # Overview +//! +//! [`tracing`] is a framework for instrumenting Rust programs with context-aware, +//! structured, event-based diagnostic information. This crate provides an +//! implementation of the [`Subscriber`] trait that records `tracing`'s `Event`s +//! and `Span`s by formatting them as text and logging them to stdout. +//! +//! # Usage +//! +//! First, add this to your `Cargo.toml` file: +//! +//! ```toml +//! [dependencies] +//! tracing-subscriber = "0.2" +//! ``` +//! +//! *Compiler support: requires rustc 1.39+* +//! +//! Add the following to your executable to initialize the default subscriber: +//! ```rust +//! use tracing_subscriber; +//! +//! tracing_subscriber::fmt::init(); +//! ``` +//! +//! ## Filtering Events with Environment Variables +//! +//! The default subscriber installed by `init` enables you to filter events +//! at runtime using environment variables (using the [`EnvFilter`]). +//! +//! The filter syntax is a superset of the [`env_logger`] syntax. +//! +//! For example: +//! - Setting `RUST_LOG=debug` enables all `Span`s and `Event`s +//! set to the log level `DEBUG` or higher +//! - Setting `RUST_LOG=my_crate=trace` enables `Span`s and `Event`s +//! in `my_crate` at all log levels +//! +//! **Note**: This should **not** be called by libraries. Libraries should use +//! [`tracing`] to publish `tracing` `Event`s. +//! +//! # Configuration +//! +//! You can configure a subscriber instead of using the defaults with +//! the following functions: +//! +//! ### Subscriber +//! +//! The [`FmtSubscriber`] formats and records `tracing` events as line-oriented logs. +//! You can create one by calling: +//! +//! ```rust +//! let subscriber = tracing_subscriber::fmt() +//! // ... add configuration +//! .finish(); +//! ``` +//! +//! You can find the configuration methods for [`FmtSubscriber`] in +//! [`SubscriberBuilder`]. +//! +//! ## Formatters +//! +//! The output format used by the layer and subscriber in this module is +//! represented by implementing the [`FormatEvent`] trait, and can be +//! customized. This module provides a number of formatter implementations: +//! +//! * [`format::Full`]: The default formatter. This emits human-readable, +//! single-line logs for each event that occurs, with the current span context +//! displayed before the formatted representation of the event. +//! +//! For example: +//! <pre><font color="#4E9A06"><b> Finished</b></font> dev [unoptimized + debuginfo] target(s) in 1.59s +//! <font color="#4E9A06"><b> Running</b></font> `target/debug/examples/fmt` +//! <font color="#AAAAAA">Oct 24 12:55:47.814 </font><font color="#4E9A06"> INFO</font> fmt: preparing to shave yaks number_of_yaks=3 +//! <font color="#AAAAAA">Oct 24 12:55:47.814 </font><font color="#4E9A06"> INFO</font> <b>shaving_yaks{</b>yaks=3<b>}</b>: fmt::yak_shave: shaving yaks +//! <font color="#AAAAAA">Oct 24 12:55:47.814 </font><font color="#75507B">TRACE</font> <b>shaving_yaks{</b>yaks=3<b>}</b>:<b>shave{</b>yak=1<b>}</b>: fmt::yak_shave: hello! I'm gonna shave a yak excitement="yay!" +//! <font color="#AAAAAA">Oct 24 12:55:47.814 </font><font color="#75507B">TRACE</font> <b>shaving_yaks{</b>yaks=3<b>}</b>:<b>shave{</b>yak=1<b>}</b>: fmt::yak_shave: yak shaved successfully +//! <font color="#AAAAAA">Oct 24 12:55:47.814 </font><font color="#3465A4">DEBUG</font> <b>shaving_yaks{</b>yaks=3<b>}</b>: yak_events: yak=1 shaved=true +//! <font color="#AAAAAA">Oct 24 12:55:47.814 </font><font color="#75507B">TRACE</font> <b>shaving_yaks{</b>yaks=3<b>}</b>: fmt::yak_shave: yaks_shaved=1 +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#75507B">TRACE</font> <b>shaving_yaks{</b>yaks=3<b>}</b>:<b>shave{</b>yak=2<b>}</b>: fmt::yak_shave: hello! I'm gonna shave a yak excitement="yay!" +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#75507B">TRACE</font> <b>shaving_yaks{</b>yaks=3<b>}</b>:<b>shave{</b>yak=2<b>}</b>: fmt::yak_shave: yak shaved successfully +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#3465A4">DEBUG</font> <b>shaving_yaks{</b>yaks=3<b>}</b>: yak_events: yak=2 shaved=true +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#75507B">TRACE</font> <b>shaving_yaks{</b>yaks=3<b>}</b>: fmt::yak_shave: yaks_shaved=2 +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#75507B">TRACE</font> <b>shaving_yaks{</b>yaks=3<b>}</b>:<b>shave{</b>yak=3<b>}</b>: fmt::yak_shave: hello! I'm gonna shave a yak excitement="yay!" +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#C4A000"> WARN</font> <b>shaving_yaks{</b>yaks=3<b>}</b>:<b>shave{</b>yak=3<b>}</b>: fmt::yak_shave: could not locate yak +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#3465A4">DEBUG</font> <b>shaving_yaks{</b>yaks=3<b>}</b>: yak_events: yak=3 shaved=false +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#CC0000">ERROR</font> <b>shaving_yaks{</b>yaks=3<b>}</b>: fmt::yak_shave: failed to shave yak yak=3 error=missing yak +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#75507B">TRACE</font> <b>shaving_yaks{</b>yaks=3<b>}</b>: fmt::yak_shave: yaks_shaved=2 +//! <font color="#AAAAAA">Oct 24 12:55:47.815 </font><font color="#4E9A06"> INFO</font> fmt: yak shaving completed all_yaks_shaved=false +//! </pre> +//! +//! * [`format::Pretty`]: Emits excessively pretty, multi-line logs, optimized +//! for human readability. This is primarily intended to be used in local +//! development and debugging, or for command-line applications, where +//! automated analysis and compact storage of logs is less of a priority than +//! readability and visual appeal. +//! +//! For example: +//! <pre><font color="#4E9A06"><b> Finished</b></font> dev [unoptimized + debuginfo] target(s) in 1.61s +//! <font color="#4E9A06"><b> Running</b></font> `target/debug/examples/fmt-pretty` +//! Oct 24 12:57:29.386 <font color="#4E9A06"><b>fmt_pretty</b></font><font color="#4E9A06">: preparing to shave yaks, </font><font color="#4E9A06"><b>number_of_yaks</b></font><font color="#4E9A06">: 3</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt-pretty.rs:16<font color="#AAAAAA"><i> on</i></font> main +//! +//! Oct 24 12:57:29.386 <font color="#4E9A06"><b>fmt_pretty::yak_shave</b></font><font color="#4E9A06">: shaving yaks</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:38<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#75507B"><b>fmt_pretty::yak_shave</b></font><font color="#75507B">: hello! I'm gonna shave a yak, </font><font color="#75507B"><b>excitement</b></font><font color="#75507B">: "yay!"</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:14<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shave</b> <font color="#AAAAAA"><i>with</i></font> <b>yak</b>: 1 +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#75507B"><b>fmt_pretty::yak_shave</b></font><font color="#75507B">: yak shaved successfully</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:22<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shave</b> <font color="#AAAAAA"><i>with</i></font> <b>yak</b>: 1 +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#3465A4"><b>yak_events</b></font><font color="#3465A4">: </font><font color="#3465A4"><b>yak</b></font><font color="#3465A4">: 1, </font><font color="#3465A4"><b>shaved</b></font><font color="#3465A4">: true</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:43<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#75507B"><b>fmt_pretty::yak_shave</b></font><font color="#75507B">: </font><font color="#75507B"><b>yaks_shaved</b></font><font color="#75507B">: 1</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:52<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#75507B"><b>fmt_pretty::yak_shave</b></font><font color="#75507B">: hello! I'm gonna shave a yak, </font><font color="#75507B"><b>excitement</b></font><font color="#75507B">: "yay!"</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:14<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shave</b> <font color="#AAAAAA"><i>with</i></font> <b>yak</b>: 2 +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#75507B"><b>fmt_pretty::yak_shave</b></font><font color="#75507B">: yak shaved successfully</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:22<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shave</b> <font color="#AAAAAA"><i>with</i></font> <b>yak</b>: 2 +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#3465A4"><b>yak_events</b></font><font color="#3465A4">: </font><font color="#3465A4"><b>yak</b></font><font color="#3465A4">: 2, </font><font color="#3465A4"><b>shaved</b></font><font color="#3465A4">: true</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:43<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#75507B"><b>fmt_pretty::yak_shave</b></font><font color="#75507B">: </font><font color="#75507B"><b>yaks_shaved</b></font><font color="#75507B">: 2</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:52<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#75507B"><b>fmt_pretty::yak_shave</b></font><font color="#75507B">: hello! I'm gonna shave a yak, </font><font color="#75507B"><b>excitement</b></font><font color="#75507B">: "yay!"</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:14<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shave</b> <font color="#AAAAAA"><i>with</i></font> <b>yak</b>: 3 +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#C4A000"><b>fmt_pretty::yak_shave</b></font><font color="#C4A000">: could not locate yak</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:16<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shave</b> <font color="#AAAAAA"><i>with</i></font> <b>yak</b>: 3 +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#3465A4"><b>yak_events</b></font><font color="#3465A4">: </font><font color="#3465A4"><b>yak</b></font><font color="#3465A4">: 3, </font><font color="#3465A4"><b>shaved</b></font><font color="#3465A4">: false</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:43<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#CC0000"><b>fmt_pretty::yak_shave</b></font><font color="#CC0000">: failed to shave yak, </font><font color="#CC0000"><b>yak</b></font><font color="#CC0000">: 3, </font><font color="#CC0000"><b>error</b></font><font color="#CC0000">: missing yak</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:48<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#75507B"><b>fmt_pretty::yak_shave</b></font><font color="#75507B">: </font><font color="#75507B"><b>yaks_shaved</b></font><font color="#75507B">: 2</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt/yak_shave.rs:52<font color="#AAAAAA"><i> on</i></font> main +//! <font color="#AAAAAA"><i>in</i></font> fmt_pretty::yak_shave::<b>shaving_yaks</b> <font color="#AAAAAA"><i>with</i></font> <b>yaks</b>: 3 +//! +//! Oct 24 12:57:29.387 <font color="#4E9A06"><b>fmt_pretty</b></font><font color="#4E9A06">: yak shaving completed, </font><font color="#4E9A06"><b>all_yaks_shaved</b></font><font color="#4E9A06">: false</font> +//! <font color="#AAAAAA"><i>at</i></font> examples/examples/fmt-pretty.rs:19<font color="#AAAAAA"><i> on</i></font> main +//! </pre> +//! +//! * [`format::Json`]: Outputs newline-delimited JSON logs. This is intended +//! for production use with systems where structured logs are consumed as JSON +//! by analysis and viewing tools. The JSON output, as seen below, is *not* +//! optimized for human readability. +//! +//! For example: +//! <pre><font color="#4E9A06"><b> Finished</b></font> dev [unoptimized + debuginfo] target(s) in 1.58s +//! <font color="#4E9A06"><b> Running</b></font> `target/debug/examples/fmt-json` +//! {"timestamp":"Oct 24 13:00:00.873","level":"INFO","fields":{"message":"preparing to shave yaks","number_of_yaks":3},"target":"fmt_json"} +//! {"timestamp":"Oct 24 13:00:00.874","level":"INFO","fields":{"message":"shaving yaks"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"TRACE","fields":{"message":"hello! I'm gonna shave a yak","excitement":"yay!"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":"1","name":"shave"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"TRACE","fields":{"message":"yak shaved successfully"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":"1","name":"shave"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"DEBUG","fields":{"yak":1,"shaved":true},"target":"yak_events","spans":[{"yaks":3,"name":"shaving_yaks"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"TRACE","fields":{"yaks_shaved":1},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"TRACE","fields":{"message":"hello! I'm gonna shave a yak","excitement":"yay!"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":"2","name":"shave"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"TRACE","fields":{"message":"yak shaved successfully"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":"2","name":"shave"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"DEBUG","fields":{"yak":2,"shaved":true},"target":"yak_events","spans":[{"yaks":3,"name":"shaving_yaks"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"TRACE","fields":{"yaks_shaved":2},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]} +//! {"timestamp":"Oct 24 13:00:00.874","level":"TRACE","fields":{"message":"hello! I'm gonna shave a yak","excitement":"yay!"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":"3","name":"shave"}]} +//! {"timestamp":"Oct 24 13:00:00.875","level":"WARN","fields":{"message":"could not locate yak"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":"3","name":"shave"}]} +//! {"timestamp":"Oct 24 13:00:00.875","level":"DEBUG","fields":{"yak":3,"shaved":false},"target":"yak_events","spans":[{"yaks":3,"name":"shaving_yaks"}]} +//! {"timestamp":"Oct 24 13:00:00.875","level":"ERROR","fields":{"message":"failed to shave yak","yak":3,"error":"missing yak"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]} +//! {"timestamp":"Oct 24 13:00:00.875","level":"TRACE","fields":{"yaks_shaved":2},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]} +//! {"timestamp":"Oct 24 13:00:00.875","level":"INFO","fields":{"message":"yak shaving completed","all_yaks_shaved":false},"target":"fmt_json"} +//! </pre> +//! +//! ### Customizing Formatters +//! +//! The formatting of log lines for spans and events is controlled by two +//! traits, [`FormatEvent`] and [`FormatFields`]. The [`FormatEvent`] trait +//! determines the overall formatting of the log line, such as what information +//! from the event's metadata and span context is included and in what order. +//! The [`FormatFields`] trait determines how fields — both the event's +//! fields and fields on spans — are formatted. +//! +//! The [`fmt::format`] module provides several types which implement these traits, +//! many of which expose additional configuration options to customize their +//! output. The [`format::Format`] type implements common configuration used by +//! all the formatters provided in this crate, and can be used as a builder to +//! set specific formatting settings. For example: +//! +//! ``` +//! use tracing_subscriber::fmt; +//! +//! // Configure a custom event formatter +//! let format = fmt::format() +//! .with_level(false) // don't include levels in formatted output +//! .with_target(false) // don't include targets +//! .with_thread_ids(true) // include the thread ID of the current thread +//! .with_thread_names(true) // include the name of the current thread +//! .compact(); // use the `Compact` formatting style. +//! +//! // Create a `fmt` collector that uses our custom event format, and set it +//! // as the default. +//! tracing_subscriber::fmt() +//! .event_format(format) +//! .init(); +//! ``` +//! +//! However, if a specific output format is needed, other crates can +//! also implement [`FormatEvent`] and [`FormatFields`]. See those traits' +//! documentation for details on how to implement them. +//! +//! ## Filters +//! +//! If you want to filter the `tracing` `Events` based on environment +//! variables, you can use the [`EnvFilter`] as follows: +//! +//! ```rust +//! use tracing_subscriber::EnvFilter; +//! +//! let filter = EnvFilter::from_default_env(); +//! ``` +//! +//! As mentioned above, the [`EnvFilter`] allows `Span`s and `Event`s to +//! be filtered at runtime by setting the `RUST_LOG` environment variable. +//! +//! You can find the other available [`filter`]s in the documentation. +//! +//! ### Using Your Subscriber +//! +//! Finally, once you have configured your `Subscriber`, you need to +//! configure your executable to use it. +//! +//! A subscriber can be installed globally using: +//! ```rust +//! use tracing; +//! use tracing_subscriber::FmtSubscriber; +//! +//! let subscriber = FmtSubscriber::new(); +//! +//! tracing::subscriber::set_global_default(subscriber) +//! .map_err(|_err| eprintln!("Unable to set global default subscriber")); +//! // Note this will only fail if you try to set the global default +//! // subscriber multiple times +//! ``` +//! +//! ### Composing Layers +//! +//! Composing an [`EnvFilter`] `Layer` and a [format `Layer`](../fmt/struct.Layer.html): +//! +//! ```rust +//! use tracing_subscriber::{fmt, EnvFilter}; +//! use tracing_subscriber::prelude::*; +//! +//! let fmt_layer = fmt::layer() +//! .with_target(false); +//! let filter_layer = EnvFilter::try_from_default_env() +//! .or_else(|_| EnvFilter::try_new("info")) +//! .unwrap(); +//! +//! tracing_subscriber::registry() +//! .with(filter_layer) +//! .with(fmt_layer) +//! .init(); +//! ``` +//! +//! [`EnvFilter`]: ../filter/struct.EnvFilter.html +//! [`env_logger`]: https://docs.rs/env_logger/ +//! [`filter`]: ../filter/index.html +//! [`SubscriberBuilder`]: ./struct.SubscriberBuilder.html +//! [`FmtSubscriber`]: ./struct.Subscriber.html +//! [`Subscriber`]: +//! https://docs.rs/tracing/latest/tracing/trait.Subscriber.html +//! [`tracing`]: https://crates.io/crates/tracing +//! [`fmt::format`]: mod@crate::fmt::format +use std::{any::TypeId, error::Error, io}; +use tracing_core::{span, subscriber::Interest, Event, Metadata}; + +mod fmt_layer; +#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))] +pub mod format; +#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))] +pub mod time; +#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))] +pub mod writer; + +pub use fmt_layer::{FmtContext, FormattedFields, Layer}; + +use crate::layer::Layer as _; +use crate::{ + filter::LevelFilter, + layer, + registry::{LookupSpan, Registry}, +}; + +#[doc(inline)] +pub use self::{ + format::{format, FormatEvent, FormatFields}, + time::time, + writer::{MakeWriter, TestWriter}, +}; + +/// A `Subscriber` that logs formatted representations of `tracing` events. +/// +/// This consists of an inner `Formatter` wrapped in a layer that performs filtering. +#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))] +#[derive(Debug)] +pub struct Subscriber< + N = format::DefaultFields, + E = format::Format<format::Full>, + F = LevelFilter, + W = fn() -> io::Stdout, +> { + inner: layer::Layered<F, Formatter<N, E, W>>, +} + +/// A `Subscriber` that logs formatted representations of `tracing` events. +/// This type only logs formatted events; it does not perform any filtering. +#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))] +pub type Formatter< + N = format::DefaultFields, + E = format::Format<format::Full>, + W = fn() -> io::Stdout, +> = layer::Layered<fmt_layer::Layer<Registry, N, E, W>, Registry>; + +/// Configures and constructs `Subscriber`s. +#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))] +#[derive(Debug)] +pub struct SubscriberBuilder< + N = format::DefaultFields, + E = format::Format<format::Full>, + F = LevelFilter, + W = fn() -> io::Stdout, +> { + filter: F, + inner: Layer<Registry, N, E, W>, +} + +/// Returns a new [`SubscriberBuilder`] for configuring a [formatting subscriber]. +/// +/// This is essentially shorthand for [`SubscriberBuilder::default()]`. +/// +/// # Examples +/// +/// Using [`init`] to set the default subscriber: +/// +/// ```rust +/// tracing_subscriber::fmt().init(); +/// ``` +/// +/// Configuring the output format: +/// +/// ```rust +/// +/// tracing_subscriber::fmt() +/// // Configure formatting settings. +/// .with_target(false) +/// .with_timer(tracing_subscriber::fmt::time::uptime()) +/// .with_level(true) +/// // Set the subscriber as the default. +/// .init(); +/// ``` +/// +/// [`try_init`] returns an error if the default subscriber could not be set: +/// +/// ```rust +/// use std::error::Error; +/// +/// fn init_subscriber() -> Result<(), Box<dyn Error + Send + Sync + 'static>> { +/// tracing_subscriber::fmt() +/// // Configure the subscriber to emit logs in JSON format. +/// .json() +/// // Configure the subscriber to flatten event fields in the output JSON objects. +/// .flatten_event(true) +/// // Set the subscriber as the default, returning an error if this fails. +/// .try_init()?; +/// +/// Ok(()) +/// } +/// ``` +/// +/// Rather than setting the subscriber as the default, [`finish`] _returns_ the +/// constructed subscriber, which may then be passed to other functions: +/// +/// ```rust +/// let subscriber = tracing_subscriber::fmt() +/// .with_max_level(tracing::Level::DEBUG) +/// .compact() +/// .finish(); +/// +/// tracing::subscriber::with_default(subscriber, || { +/// // the subscriber will only be set as the default +/// // inside this closure... +/// }) +/// ``` +/// +/// [formatting subscriber]: Subscriber +/// [`SubscriberBuilder::default()`]: SubscriberBuilder::default() +/// [`init`]: SubscriberBuilder::init() +/// [`try_init`]: SubscriberBuilder::try_init() +/// [`finish`]: SubscriberBuilder::finish() +#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))] +pub fn fmt() -> SubscriberBuilder { + SubscriberBuilder::default() +} + +/// Returns a new [formatting layer] that can be [composed] with other layers to +/// construct a [`Subscriber`]. +/// +/// This is a shorthand for the equivalent [`Layer::default`] function. +/// +/// [formatting layer]: Layer +/// [composed]: crate::layer +#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))] +pub fn layer<S>() -> Layer<S> { + Layer::default() +} + +impl Subscriber { + /// The maximum [verbosity level] that is enabled by a `Subscriber` by + /// default. + /// + /// This can be overridden with the [`SubscriberBuilder::with_max_level`] method. + /// + /// [verbosity level]: https://docs.rs/tracing-core/0.1.5/tracing_core/struct.Level.html + /// [`SubscriberBuilder::with_max_level`]: struct.SubscriberBuilder.html#method.with_max_level + pub const DEFAULT_MAX_LEVEL: LevelFilter = LevelFilter::INFO; + + /// Returns a new `SubscriberBuilder` for configuring a format subscriber. + pub fn builder() -> SubscriberBuilder { + SubscriberBuilder::default() + } + + /// Returns a new format subscriber with the default configuration. + pub fn new() -> Self { + Default::default() + } +} + +impl Default for Subscriber { + fn default() -> Self { + SubscriberBuilder::default().finish() + } +} + +// === impl Subscriber === + +impl<N, E, F, W> tracing_core::Subscriber for Subscriber<N, E, F, W> +where + N: for<'writer> FormatFields<'writer> + 'static, + E: FormatEvent<Registry, N> + 'static, + F: layer::Layer<Formatter<N, E, W>> + 'static, + W: for<'writer> MakeWriter<'writer> + 'static, + layer::Layered<F, Formatter<N, E, W>>: tracing_core::Subscriber, + fmt_layer::Layer<Registry, N, E, W>: layer::Layer<Registry>, +{ + #[inline] + fn register_callsite(&self, meta: &'static Metadata<'static>) -> Interest { + self.inner.register_callsite(meta) + } + + #[inline] + fn enabled(&self, meta: &Metadata<'_>) -> bool { + self.inner.enabled(meta) + } + + #[inline] + fn new_span(&self, attrs: &span::Attributes<'_>) -> span::Id { + self.inner.new_span(attrs) + } + + #[inline] + fn record(&self, span: &span::Id, values: &span::Record<'_>) { + self.inner.record(span, values) + } + + #[inline] + fn record_follows_from(&self, span: &span::Id, follows: &span::Id) { + self.inner.record_follows_from(span, follows) + } + + #[inline] + fn event(&self, event: &Event<'_>) { + self.inner.event(event); + } + + #[inline] + fn enter(&self, id: &span::Id) { + // TODO: add on_enter hook + self.inner.enter(id); + } + + #[inline] + fn exit(&self, id: &span::Id) { + self.inner.exit(id); + } + + #[inline] + fn current_span(&self) -> span::Current { + self.inner.current_span() + } + + #[inline] + fn clone_span(&self, id: &span::Id) -> span::Id { + self.inner.clone_span(id) + } + + #[inline] + fn try_close(&self, id: span::Id) -> bool { + self.inner.try_close(id) + } + + #[inline] + fn max_level_hint(&self) -> Option<tracing_core::LevelFilter> { + self.inner.max_level_hint() + } + + unsafe fn downcast_raw(&self, id: TypeId) -> Option<*const ()> { + if id == TypeId::of::<Self>() { + Some(self as *const Self as *const ()) + } else { + self.inner.downcast_raw(id) + } + } +} + +impl<'a, N, E, F, W> LookupSpan<'a> for Subscriber<N, E, F, W> +where + layer::Layered<F, Formatter<N, E, W>>: LookupSpan<'a>, +{ + type Data = <layer::Layered<F, Formatter<N, E, W>> as LookupSpan<'a>>::Data; + + fn span_data(&'a self, id: &span::Id) -> Option<Self::Data> { + self.inner.span_data(id) + } +} + +// ===== impl SubscriberBuilder ===== + +impl Default for SubscriberBuilder { + fn default() -> Self { + SubscriberBuilder { + filter: Subscriber::DEFAULT_MAX_LEVEL, + inner: Default::default(), + } + } +} + +impl<N, E, F, W> SubscriberBuilder<N, E, F, W> +where + N: for<'writer> FormatFields<'writer> + 'static, + E: FormatEvent<Registry, N> + 'static, + W: for<'writer> MakeWriter<'writer> + 'static, + F: layer::Layer<Formatter<N, E, W>> + Send + Sync + 'static, + fmt_layer::Layer<Registry, N, E, W>: layer::Layer<Registry> + Send + Sync + 'static, +{ + /// Finish the builder, returning a new `FmtSubscriber`. + pub fn finish(self) -> Subscriber<N, E, F, W> { + let subscriber = self.inner.with_subscriber(Registry::default()); + Subscriber { + inner: self.filter.with_subscriber(subscriber), + } + } + + /// Install this Subscriber as the global default if one is + /// not already set. + /// + /// If the `tracing-log` feature is enabled, this will also install + /// the LogTracer to convert `Log` records into `tracing` `Event`s. + /// + /// # Errors + /// Returns an Error if the initialization was unsuccessful, likely + /// because a global subscriber was already installed by another + /// call to `try_init`. + pub fn try_init(self) -> Result<(), Box<dyn Error + Send + Sync + 'static>> { + use crate::util::SubscriberInitExt; + self.finish().try_init()?; + + Ok(()) + } + + /// Install this Subscriber as the global default. + /// + /// If the `tracing-log` feature is enabled, this will also install + /// the LogTracer to convert `Log` records into `tracing` `Event`s. + /// + /// # Panics + /// Panics if the initialization was unsuccessful, likely because a + /// global subscriber was already installed by another call to `try_init`. + pub fn init(self) { + self.try_init() + .expect("Unable to install global subscriber") + } +} + +impl<N, E, F, W> From<SubscriberBuilder<N, E, F, W>> for tracing_core::Dispatch +where + N: for<'writer> FormatFields<'writer> + 'static, + E: FormatEvent<Registry, N> + 'static, + W: for<'writer> MakeWriter<'writer> + 'static, + F: layer::Layer<Formatter<N, E, W>> + Send + Sync + 'static, + fmt_layer::Layer<Registry, N, E, W>: layer::Layer<Registry> + Send + Sync + 'static, +{ + fn from(builder: SubscriberBuilder<N, E, F, W>) -> tracing_core::Dispatch { + tracing_core::Dispatch::new(builder.finish()) + } +} + +impl<N, L, T, F, W> SubscriberBuilder<N, format::Format<L, T>, F, W> +where + N: for<'writer> FormatFields<'writer> + 'static, +{ + /// Use the given [`timer`] for log message timestamps. + /// + /// See the [`time` module] for the provided timer implementations. + /// + /// Note that using the `"time`"" feature flag enables the + /// additional time formatters [`UtcTime`] and [`LocalTime`], which use the + /// [`time` crate] to provide more sophisticated timestamp formatting + /// options. + /// + /// [`timer`]: time::FormatTime + /// [`time` module]: mod@time + /// [`UtcTime`]: time::UtcTime + /// [`LocalTime`]: time::LocalTime + /// [`time` crate]: https://docs.rs/time/0.3 + pub fn with_timer<T2>(self, timer: T2) -> SubscriberBuilder<N, format::Format<L, T2>, F, W> { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.with_timer(timer), + } + } + + /// Do not emit timestamps with log messages. + pub fn without_time(self) -> SubscriberBuilder<N, format::Format<L, ()>, F, W> { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.without_time(), + } + } + + /// Configures how synthesized events are emitted at points in the [span + /// lifecycle][lifecycle]. + /// + /// The following options are available: + /// + /// - `FmtSpan::NONE`: No events will be synthesized when spans are + /// created, entered, exited, or closed. Data from spans will still be + /// included as the context for formatted events. This is the default. + /// - `FmtSpan::NEW`: An event will be synthesized when spans are created. + /// - `FmtSpan::ENTER`: An event will be synthesized when spans are entered. + /// - `FmtSpan::EXIT`: An event will be synthesized when spans are exited. + /// - `FmtSpan::CLOSE`: An event will be synthesized when a span closes. If + /// [timestamps are enabled][time] for this formatter, the generated + /// event will contain fields with the span's _busy time_ (the total + /// time for which it was entered) and _idle time_ (the total time that + /// the span existed but was not entered). + /// - `FmtSpan::ACTIVE`: An event will be synthesized when spans are entered + /// or exited. + /// - `FmtSpan::FULL`: Events will be synthesized whenever a span is + /// created, entered, exited, or closed. If timestamps are enabled, the + /// close event will contain the span's busy and idle time, as + /// described above. + /// + /// The options can be enabled in any combination. For instance, the following + /// will synthesize events whenever spans are created and closed: + /// + /// ```rust + /// use tracing_subscriber::fmt::format::FmtSpan; + /// use tracing_subscriber::fmt; + /// + /// let subscriber = fmt() + /// .with_span_events(FmtSpan::NEW | FmtSpan::CLOSE) + /// .finish(); + /// ``` + /// + /// Note that the generated events will only be part of the log output by + /// this formatter; they will not be recorded by other `Subscriber`s or by + /// `Layer`s added to this subscriber. + /// + /// [lifecycle]: https://docs.rs/tracing/latest/tracing/span/index.html#the-span-lifecycle + /// [time]: #method.without_time + pub fn with_span_events(self, kind: format::FmtSpan) -> Self { + SubscriberBuilder { + inner: self.inner.with_span_events(kind), + ..self + } + } + + /// Enable ANSI encoding for formatted events. + #[cfg(feature = "ansi")] + #[cfg_attr(docsrs, doc(cfg(feature = "ansi")))] + pub fn with_ansi(self, ansi: bool) -> SubscriberBuilder<N, format::Format<L, T>, F, W> { + SubscriberBuilder { + inner: self.inner.with_ansi(ansi), + ..self + } + } + + /// Sets whether or not an event's target is displayed. + pub fn with_target( + self, + display_target: bool, + ) -> SubscriberBuilder<N, format::Format<L, T>, F, W> { + SubscriberBuilder { + inner: self.inner.with_target(display_target), + ..self + } + } + + /// Sets whether or not an event's level is displayed. + pub fn with_level( + self, + display_level: bool, + ) -> SubscriberBuilder<N, format::Format<L, T>, F, W> { + SubscriberBuilder { + inner: self.inner.with_level(display_level), + ..self + } + } + + /// Sets whether or not the [name] of the current thread is displayed + /// when formatting events + /// + /// [name]: https://doc.rust-lang.org/stable/std/thread/index.html#naming-threads + pub fn with_thread_names( + self, + display_thread_names: bool, + ) -> SubscriberBuilder<N, format::Format<L, T>, F, W> { + SubscriberBuilder { + inner: self.inner.with_thread_names(display_thread_names), + ..self + } + } + + /// Sets whether or not the [thread ID] of the current thread is displayed + /// when formatting events + /// + /// [thread ID]: https://doc.rust-lang.org/stable/std/thread/struct.ThreadId.html + pub fn with_thread_ids( + self, + display_thread_ids: bool, + ) -> SubscriberBuilder<N, format::Format<L, T>, F, W> { + SubscriberBuilder { + inner: self.inner.with_thread_ids(display_thread_ids), + ..self + } + } + + /// Sets the subscriber being built to use a less verbose formatter. + /// + /// See [`format::Compact`]. + pub fn compact(self) -> SubscriberBuilder<N, format::Format<format::Compact, T>, F, W> + where + N: for<'writer> FormatFields<'writer> + 'static, + { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.compact(), + } + } + + /// Sets the subscriber being built to use an [excessively pretty, human-readable formatter](crate::fmt::format::Pretty). + #[cfg(feature = "ansi")] + #[cfg_attr(docsrs, doc(cfg(feature = "ansi")))] + pub fn pretty( + self, + ) -> SubscriberBuilder<format::Pretty, format::Format<format::Pretty, T>, F, W> { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.pretty(), + } + } + + /// Sets the subscriber being built to use a JSON formatter. + /// + /// See [`format::Json`](../fmt/format/struct.Json.html) + #[cfg(feature = "json")] + #[cfg_attr(docsrs, doc(cfg(feature = "json")))] + pub fn json( + self, + ) -> SubscriberBuilder<format::JsonFields, format::Format<format::Json, T>, F, W> + where + N: for<'writer> FormatFields<'writer> + 'static, + { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.json(), + } + } +} + +#[cfg(feature = "json")] +#[cfg_attr(docsrs, doc(cfg(feature = "json")))] +impl<T, F, W> SubscriberBuilder<format::JsonFields, format::Format<format::Json, T>, F, W> { + /// Sets the json subscriber being built to flatten event metadata. + /// + /// See [`format::Json`](../fmt/format/struct.Json.html) + pub fn flatten_event( + self, + flatten_event: bool, + ) -> SubscriberBuilder<format::JsonFields, format::Format<format::Json, T>, F, W> { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.flatten_event(flatten_event), + } + } + + /// Sets whether or not the JSON subscriber being built will include the current span + /// in formatted events. + /// + /// See [`format::Json`](../fmt/format/struct.Json.html) + pub fn with_current_span( + self, + display_current_span: bool, + ) -> SubscriberBuilder<format::JsonFields, format::Format<format::Json, T>, F, W> { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.with_current_span(display_current_span), + } + } + + /// Sets whether or not the JSON subscriber being built will include a list (from + /// root to leaf) of all currently entered spans in formatted events. + /// + /// See [`format::Json`](../fmt/format/struct.Json.html) + pub fn with_span_list( + self, + display_span_list: bool, + ) -> SubscriberBuilder<format::JsonFields, format::Format<format::Json, T>, F, W> { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.with_span_list(display_span_list), + } + } +} + +#[cfg(feature = "env-filter")] +#[cfg_attr(docsrs, doc(cfg(feature = "env-filter")))] +impl<N, E, W> SubscriberBuilder<N, E, crate::EnvFilter, W> +where + Formatter<N, E, W>: tracing_core::Subscriber + 'static, +{ + /// Configures the subscriber being built to allow filter reloading at + /// runtime. + pub fn with_filter_reloading( + self, + ) -> SubscriberBuilder<N, E, crate::reload::Layer<crate::EnvFilter, Formatter<N, E, W>>, W> + { + let (filter, _) = crate::reload::Layer::new(self.filter); + SubscriberBuilder { + filter, + inner: self.inner, + } + } +} + +#[cfg(feature = "env-filter")] +#[cfg_attr(docsrs, doc(cfg(feature = "env-filter")))] +impl<N, E, W> SubscriberBuilder<N, E, crate::reload::Layer<crate::EnvFilter, Formatter<N, E, W>>, W> +where + Formatter<N, E, W>: tracing_core::Subscriber + 'static, +{ + /// Returns a `Handle` that may be used to reload the constructed subscriber's + /// filter. + pub fn reload_handle(&self) -> crate::reload::Handle<crate::EnvFilter, Formatter<N, E, W>> { + self.filter.handle() + } +} + +impl<N, E, F, W> SubscriberBuilder<N, E, F, W> { + /// Sets the Visitor that the subscriber being built will use to record + /// fields. + /// + /// For example: + /// ```rust + /// use tracing_subscriber::fmt::format; + /// use tracing_subscriber::prelude::*; + /// + /// let formatter = + /// // Construct a custom formatter for `Debug` fields + /// format::debug_fn(|writer, field, value| write!(writer, "{}: {:?}", field, value)) + /// // Use the `tracing_subscriber::MakeFmtExt` trait to wrap the + /// // formatter so that a delimiter is added between fields. + /// .delimited(", "); + /// + /// let subscriber = tracing_subscriber::fmt() + /// .fmt_fields(formatter) + /// .finish(); + /// # drop(subscriber) + /// ``` + pub fn fmt_fields<N2>(self, fmt_fields: N2) -> SubscriberBuilder<N2, E, F, W> + where + N2: for<'writer> FormatFields<'writer> + 'static, + { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.fmt_fields(fmt_fields), + } + } + + /// Sets the [`EnvFilter`] that the subscriber will use to determine if + /// a span or event is enabled. + /// + /// Note that this method requires the "env-filter" feature flag to be enabled. + /// + /// If a filter was previously set, or a maximum level was set by the + /// [`with_max_level`] method, that value is replaced by the new filter. + /// + /// # Examples + /// + /// Setting a filter based on the value of the `RUST_LOG` environment + /// variable: + /// ```rust + /// use tracing_subscriber::{fmt, EnvFilter}; + /// + /// fmt() + /// .with_env_filter(EnvFilter::from_default_env()) + /// .init(); + /// ``` + /// + /// Setting a filter based on a pre-set filter directive string: + /// ```rust + /// use tracing_subscriber::fmt; + /// + /// fmt() + /// .with_env_filter("my_crate=info,my_crate::my_mod=debug,[my_span]=trace") + /// .init(); + /// ``` + /// + /// Adding additional directives to a filter constructed from an env var: + /// ```rust + /// use tracing_subscriber::{fmt, filter::{EnvFilter, LevelFilter}}; + /// + /// # fn filter() -> Result<(), Box<dyn std::error::Error + Send + Sync + 'static>> { + /// let filter = EnvFilter::try_from_env("MY_CUSTOM_FILTER_ENV_VAR")? + /// // Set the base level when not matched by other directives to WARN. + /// .add_directive(LevelFilter::WARN.into()) + /// // Set the max level for `my_crate::my_mod` to DEBUG, overriding + /// // any directives parsed from the env variable. + /// .add_directive("my_crate::my_mod=debug".parse()?); + /// + /// fmt() + /// .with_env_filter(filter) + /// .try_init()?; + /// # Ok(())} + /// ``` + /// [`EnvFilter`]: ../filter/struct.EnvFilter.html + /// [`with_max_level`]: #method.with_max_level + #[cfg(feature = "env-filter")] + #[cfg_attr(docsrs, doc(cfg(feature = "env-filter")))] + pub fn with_env_filter( + self, + filter: impl Into<crate::EnvFilter>, + ) -> SubscriberBuilder<N, E, crate::EnvFilter, W> + where + Formatter<N, E, W>: tracing_core::Subscriber + 'static, + { + let filter = filter.into(); + SubscriberBuilder { + filter, + inner: self.inner, + } + } + + /// Sets the maximum [verbosity level] that will be enabled by the + /// subscriber. + /// + /// If the max level has already been set, or a [`EnvFilter`] was added by + /// [`with_filter`], this replaces that configuration with the new + /// maximum level. + /// + /// # Examples + /// + /// Enable up to the `DEBUG` verbosity level: + /// ```rust + /// use tracing_subscriber::fmt; + /// use tracing::Level; + /// + /// fmt() + /// .with_max_level(Level::DEBUG) + /// .init(); + /// ``` + /// This subscriber won't record any spans or events! + /// ```rust + /// use tracing_subscriber::{fmt, filter::LevelFilter}; + /// + /// let subscriber = fmt() + /// .with_max_level(LevelFilter::OFF) + /// .finish(); + /// ``` + /// [verbosity level]: https://docs.rs/tracing-core/0.1.5/tracing_core/struct.Level.html + /// [`EnvFilter`]: ../filter/struct.EnvFilter.html + /// [`with_filter`]: #method.with_filter + pub fn with_max_level( + self, + filter: impl Into<LevelFilter>, + ) -> SubscriberBuilder<N, E, LevelFilter, W> { + let filter = filter.into(); + SubscriberBuilder { + filter, + inner: self.inner, + } + } + + /// Sets the function that the subscriber being built should use to format + /// events that occur. + pub fn event_format<E2>(self, fmt_event: E2) -> SubscriberBuilder<N, E2, F, W> + where + E2: FormatEvent<Registry, N> + 'static, + N: for<'writer> FormatFields<'writer> + 'static, + W: for<'writer> MakeWriter<'writer> + 'static, + { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.event_format(fmt_event), + } + } + + /// Sets the [`MakeWriter`] that the subscriber being built will use to write events. + /// + /// # Examples + /// + /// Using `stderr` rather than `stdout`: + /// + /// ```rust + /// use tracing_subscriber::fmt; + /// use std::io; + /// + /// fmt() + /// .with_writer(io::stderr) + /// .init(); + /// ``` + /// + /// [`MakeWriter`]: trait.MakeWriter.html + pub fn with_writer<W2>(self, make_writer: W2) -> SubscriberBuilder<N, E, F, W2> + where + W2: for<'writer> MakeWriter<'writer> + 'static, + { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.with_writer(make_writer), + } + } + + /// Configures the subscriber to support [`libtest`'s output capturing][capturing] when used in + /// unit tests. + /// + /// See [`TestWriter`] for additional details. + /// + /// # Examples + /// + /// Using [`TestWriter`] to let `cargo test` capture test output. Note that we do not install it + /// globally as it may cause conflicts. + /// + /// ```rust + /// use tracing_subscriber::fmt; + /// use tracing::subscriber; + /// + /// subscriber::set_default( + /// fmt() + /// .with_test_writer() + /// .finish() + /// ); + /// ``` + /// + /// [capturing]: + /// https://doc.rust-lang.org/book/ch11-02-running-tests.html#showing-function-output + /// [`TestWriter`]: writer/struct.TestWriter.html + pub fn with_test_writer(self) -> SubscriberBuilder<N, E, F, TestWriter> { + SubscriberBuilder { + filter: self.filter, + inner: self.inner.with_writer(TestWriter::default()), + } + } +} + +/// Install a global tracing subscriber that listens for events and +/// filters based on the value of the [`RUST_LOG` environment variable], +/// if one is not already set. +/// +/// If the `tracing-log` feature is enabled, this will also install +/// the [`LogTracer`] to convert `log` records into `tracing` `Event`s. +/// +/// This is shorthand for +/// +/// ```rust +/// # fn doc() -> Result<(), Box<dyn std::error::Error + Send + Sync + 'static>> { +/// tracing_subscriber::fmt().try_init() +/// # } +/// ``` +/// +/// +/// # Errors +/// +/// Returns an Error if the initialization was unsuccessful, +/// likely because a global subscriber was already installed by another +/// call to `try_init`. +/// +/// [`LogTracer`]: +/// https://docs.rs/tracing-log/0.1.0/tracing_log/struct.LogTracer.html +/// [`RUST_LOG` environment variable]: +/// ../filter/struct.EnvFilter.html#associatedconstant.DEFAULT_ENV +pub fn try_init() -> Result<(), Box<dyn Error + Send + Sync + 'static>> { + let builder = Subscriber::builder(); + + #[cfg(feature = "env-filter")] + let builder = builder.with_env_filter(crate::EnvFilter::from_default_env()); + + builder.try_init() +} + +/// Install a global tracing subscriber that listens for events and +/// filters based on the value of the [`RUST_LOG` environment variable]. +/// +/// If the `tracing-log` feature is enabled, this will also install +/// the LogTracer to convert `Log` records into `tracing` `Event`s. +/// +/// This is shorthand for +/// +/// ```rust +/// tracing_subscriber::fmt().init() +/// ``` +/// +/// # Panics +/// Panics if the initialization was unsuccessful, likely because a +/// global subscriber was already installed by another call to `try_init`. +/// +/// [`RUST_LOG` environment variable]: +/// ../filter/struct.EnvFilter.html#associatedconstant.DEFAULT_ENV +pub fn init() { + try_init().expect("Unable to install global subscriber") +} + +#[cfg(test)] +mod test { + use crate::{ + filter::LevelFilter, + fmt::{ + format::{self, Format}, + time, + writer::MakeWriter, + Subscriber, + }, + }; + use std::{ + io, + sync::{Arc, Mutex, MutexGuard, TryLockError}, + }; + use tracing_core::dispatcher::Dispatch; + + pub(crate) struct MockWriter { + buf: Arc<Mutex<Vec<u8>>>, + } + + impl MockWriter { + pub(crate) fn new(buf: Arc<Mutex<Vec<u8>>>) -> Self { + Self { buf } + } + + pub(crate) fn map_error<Guard>(err: TryLockError<Guard>) -> io::Error { + match err { + TryLockError::WouldBlock => io::Error::from(io::ErrorKind::WouldBlock), + TryLockError::Poisoned(_) => io::Error::from(io::ErrorKind::Other), + } + } + + pub(crate) fn buf(&self) -> io::Result<MutexGuard<'_, Vec<u8>>> { + self.buf.try_lock().map_err(Self::map_error) + } + } + + impl io::Write for MockWriter { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.buf()?.write(buf) + } + + fn flush(&mut self) -> io::Result<()> { + self.buf()?.flush() + } + } + + #[derive(Clone, Default)] + pub(crate) struct MockMakeWriter { + buf: Arc<Mutex<Vec<u8>>>, + } + + impl MockMakeWriter { + pub(crate) fn new(buf: Arc<Mutex<Vec<u8>>>) -> Self { + Self { buf } + } + + #[cfg(feature = "json")] + pub(crate) fn buf(&self) -> MutexGuard<'_, Vec<u8>> { + self.buf.lock().unwrap() + } + + pub(crate) fn get_string(&self) -> String { + let mut buf = self.buf.lock().expect("lock shouldn't be poisoned"); + let string = std::str::from_utf8(&buf[..]) + .expect("formatter should not have produced invalid utf-8") + .to_owned(); + buf.clear(); + string + } + } + + impl<'a> MakeWriter<'a> for MockMakeWriter { + type Writer = MockWriter; + + fn make_writer(&'a self) -> Self::Writer { + MockWriter::new(self.buf.clone()) + } + } + + #[test] + fn impls() { + let f = Format::default().with_timer(time::Uptime::default()); + let subscriber = Subscriber::builder().event_format(f).finish(); + let _dispatch = Dispatch::new(subscriber); + + let f = format::Format::default(); + let subscriber = Subscriber::builder().event_format(f).finish(); + let _dispatch = Dispatch::new(subscriber); + + let f = format::Format::default().compact(); + let subscriber = Subscriber::builder().event_format(f).finish(); + let _dispatch = Dispatch::new(subscriber); + } + + #[test] + fn subscriber_downcasts() { + let subscriber = Subscriber::builder().finish(); + let dispatch = Dispatch::new(subscriber); + assert!(dispatch.downcast_ref::<Subscriber>().is_some()); + } + + #[test] + fn subscriber_downcasts_to_parts() { + let subscriber = Subscriber::new(); + let dispatch = Dispatch::new(subscriber); + assert!(dispatch.downcast_ref::<format::DefaultFields>().is_some()); + assert!(dispatch.downcast_ref::<LevelFilter>().is_some()); + assert!(dispatch.downcast_ref::<format::Format>().is_some()) + } + + #[test] + fn is_lookup_span() { + fn assert_lookup_span<T: for<'a> crate::registry::LookupSpan<'a>>(_: T) {} + let subscriber = Subscriber::new(); + assert_lookup_span(subscriber) + } +} |