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Diffstat (limited to 'third_party/rust/env_logger/src/lib.rs')
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diff --git a/third_party/rust/env_logger/src/lib.rs b/third_party/rust/env_logger/src/lib.rs new file mode 100644 index 0000000000..59fa2a3e1d --- /dev/null +++ b/third_party/rust/env_logger/src/lib.rs @@ -0,0 +1,1311 @@ +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! A simple logger that can be configured via environment variables, for use +//! with the logging facade exposed by the [`log` crate][log-crate-url]. +//! +//! Despite having "env" in its name, **`env_logger`** can also be configured by +//! other means besides environment variables. See [the examples][gh-repo-examples] +//! in the source repository for more approaches. +//! +//! By default, `env_logger` writes logs to `stderr`, but can be configured to +//! instead write them to `stdout`. +//! +//! ## Example +//! +//! ``` +//! use log::{debug, error, log_enabled, info, Level}; +//! +//! env_logger::init(); +//! +//! debug!("this is a debug {}", "message"); +//! error!("this is printed by default"); +//! +//! if log_enabled!(Level::Info) { +//! let x = 3 * 4; // expensive computation +//! info!("the answer was: {}", x); +//! } +//! ``` +//! +//! Assumes the binary is `main`: +//! +//! ```{.bash} +//! $ RUST_LOG=error ./main +//! [2017-11-09T02:12:24Z ERROR main] this is printed by default +//! ``` +//! +//! ```{.bash} +//! $ RUST_LOG=info ./main +//! [2017-11-09T02:12:24Z ERROR main] this is printed by default +//! [2017-11-09T02:12:24Z INFO main] the answer was: 12 +//! ``` +//! +//! ```{.bash} +//! $ RUST_LOG=debug ./main +//! [2017-11-09T02:12:24Z DEBUG main] this is a debug message +//! [2017-11-09T02:12:24Z ERROR main] this is printed by default +//! [2017-11-09T02:12:24Z INFO main] the answer was: 12 +//! ``` +//! +//! You can also set the log level on a per module basis: +//! +//! ```{.bash} +//! $ RUST_LOG=main=info ./main +//! [2017-11-09T02:12:24Z ERROR main] this is printed by default +//! [2017-11-09T02:12:24Z INFO main] the answer was: 12 +//! ``` +//! +//! And enable all logging: +//! +//! ```{.bash} +//! $ RUST_LOG=main ./main +//! [2017-11-09T02:12:24Z DEBUG main] this is a debug message +//! [2017-11-09T02:12:24Z ERROR main] this is printed by default +//! [2017-11-09T02:12:24Z INFO main] the answer was: 12 +//! ``` +//! +//! If the binary name contains hyphens, you will need to replace +//! them with underscores: +//! +//! ```{.bash} +//! $ RUST_LOG=my_app ./my-app +//! [2017-11-09T02:12:24Z DEBUG my_app] this is a debug message +//! [2017-11-09T02:12:24Z ERROR my_app] this is printed by default +//! [2017-11-09T02:12:24Z INFO my_app] the answer was: 12 +//! ``` +//! +//! This is because Rust modules and crates cannot contain hyphens +//! in their name, although `cargo` continues to accept them. +//! +//! See the documentation for the [`log` crate][log-crate-url] for more +//! information about its API. +//! +//! ## Enabling logging +//! +//! Log levels are controlled on a per-module basis, and **by default all +//! logging is disabled except for the `error` level**. +//! +//! Logging is controlled via the **`RUST_LOG`** environment variable. The +//! value of this environment variable is a comma-separated list of *logging +//! directives*. A logging directive is of the form: +//! +//! ```text +//! example::log::target=level +//! ``` +//! +//! The log target is typically equal to the path of the module the message +//! in question originated from, though it can be overridden. +//! +//! The path is rooted in the name of the crate it was compiled for, so if +//! your program is in a file called, for example, `hello.rs`, the path would +//! simply be be `hello`. +//! +//! Furthermore, the log can be filtered using prefix-search based on the +//! specified log target. A value of, for example, `RUST_LOG=example`, would +//! match all of the messages with targets: +//! +//! * `example` +//! * `example::test` +//! * `example::test::module::submodule` +//! * `examples::and_more_examples` +//! +//! When providing the crate name or a module path, explicitly specifying the +//! log level is optional. If omitted, all logging for the item will be +//! enabled. +//! +//! The names of the log levels that may be specified correspond to the +//! variations of the [`log::Level`][level-enum] enum from the `log` +//! crate. They are: +//! +//! * `error` +//! * `warn` +//! * `info` +//! * `debug` +//! * `trace` +//! +//! There is also a pseudo logging level, `off`, which may be specified to +//! disable all logging for a given module or for the entire application. As +//! with the logging levels, the letter case is not significant[^fn-off]. +//! +//! [^fn-off]: Similar to the universe of log level names, the `off` pseudo +//! log level feature is also provided by the underlying `log` crate. +//! +//! The letter case is not significant for the logging level names; e.g., +//! `debug`, `DEBUG`, and `dEbuG` all represent the same logging level. For +//! consistency, our convention is to use the lower case names. Where our docs +//! do use other forms, they do so in the context of specific examples, so you +//! won't be surprised if you see similar usage in the wild. +//! +//! As the log level for a module is optional, the module to enable logging for +//! is also optional. **If only a level is provided, then the global log +//! level for all modules is set to this value.** +//! +//! Some examples of valid values of `RUST_LOG` are: +//! +//! * `hello` turns on all logging for the 'hello' module +//! * `trace` turns on all logging for the application, regardless of its name +//! * `TRACE` turns on all logging for the application, regardless of its name (same as previous) +//! * `info` turns on all info logging +//! * `INFO` turns on all info logging (same as previous) +//! * `hello=debug` turns on debug logging for 'hello' +//! * `hello=DEBUG` turns on debug logging for 'hello' (same as previous) +//! * `hello,std::option` turns on hello, and std's option logging +//! * `error,hello=warn` turn on global error logging and also warn for hello +//! * `error,hello=off` turn on global error logging, but turn off logging for hello +//! * `off` turns off all logging for the application +//! * `OFF` turns off all logging for the application (same as previous) +//! +//! ## Filtering results +//! +//! A `RUST_LOG` directive may include a regex filter. The syntax is to append `/` +//! followed by a regex. Each message is checked against the regex, and is only +//! logged if it matches. Note that the matching is done after formatting the +//! log string but before adding any logging meta-data. There is a single filter +//! for all modules. +//! +//! Some examples: +//! +//! * `hello/foo` turns on all logging for the 'hello' module where the log +//! message includes 'foo'. +//! * `info/f.o` turns on all info logging where the log message includes 'foo', +//! 'f1o', 'fao', etc. +//! * `hello=debug/foo*foo` turns on debug logging for 'hello' where the log +//! message includes 'foofoo' or 'fofoo' or 'fooooooofoo', etc. +//! * `error,hello=warn/[0-9]scopes` turn on global error logging and also +//! warn for hello. In both cases the log message must include a single digit +//! number followed by 'scopes'. +//! +//! ## Capturing logs in tests +//! +//! Records logged during `cargo test` will not be captured by the test harness by default. +//! The [`Builder::is_test`] method can be used in unit tests to ensure logs will be captured: +//! +//! ``` +//! # #[macro_use] extern crate log; +//! #[cfg(test)] +//! mod tests { +//! fn init() { +//! let _ = env_logger::builder().is_test(true).try_init(); +//! } +//! +//! #[test] +//! fn it_works() { +//! init(); +//! +//! info!("This record will be captured by `cargo test`"); +//! +//! assert_eq!(2, 1 + 1); +//! } +//! } +//! ``` +//! +//! Enabling test capturing comes at the expense of color and other style support +//! and may have performance implications. +//! +//! ## Disabling colors +//! +//! Colors and other styles can be configured with the `RUST_LOG_STYLE` +//! environment variable. It accepts the following values: +//! +//! * `auto` (default) will attempt to print style characters, but don't force the issue. +//! If the console isn't available on Windows, or if TERM=dumb, for example, then don't print colors. +//! * `always` will always print style characters even if they aren't supported by the terminal. +//! This includes emitting ANSI colors on Windows if the console API is unavailable. +//! * `never` will never print style characters. +//! +//! ## Tweaking the default format +//! +//! Parts of the default format can be excluded from the log output using the [`Builder`]. +//! The following example excludes the timestamp from the log output: +//! +//! ``` +//! env_logger::builder() +//! .format_timestamp(None) +//! .init(); +//! ``` +//! +//! ### Stability of the default format +//! +//! The default format won't optimise for long-term stability, and explicitly makes no +//! guarantees about the stability of its output across major, minor or patch version +//! bumps during `0.x`. +//! +//! If you want to capture or interpret the output of `env_logger` programmatically +//! then you should use a custom format. +//! +//! ### Using a custom format +//! +//! Custom formats can be provided as closures to the [`Builder`]. +//! These closures take a [`Formatter`] and `log::Record` as arguments: +//! +//! ``` +//! use std::io::Write; +//! +//! env_logger::builder() +//! .format(|buf, record| { +//! writeln!(buf, "{}: {}", record.level(), record.args()) +//! }) +//! .init(); +//! ``` +//! +//! See the [`fmt`] module for more details about custom formats. +//! +//! ## Specifying defaults for environment variables +//! +//! `env_logger` can read configuration from environment variables. +//! If these variables aren't present, the default value to use can be tweaked with the [`Env`] type. +//! The following example defaults to log `warn` and above if the `RUST_LOG` environment variable +//! isn't set: +//! +//! ``` +//! use env_logger::Env; +//! +//! env_logger::Builder::from_env(Env::default().default_filter_or("warn")).init(); +//! ``` +//! +//! [gh-repo-examples]: https://github.com/env-logger-rs/env_logger/tree/main/examples +//! [level-enum]: https://docs.rs/log/latest/log/enum.Level.html +//! [log-crate-url]: https://docs.rs/log/ +//! [`Builder`]: struct.Builder.html +//! [`Builder::is_test`]: struct.Builder.html#method.is_test +//! [`Env`]: struct.Env.html +//! [`fmt`]: fmt/index.html + +#![doc( + html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png", + html_favicon_url = "https://www.rust-lang.org/static/images/favicon.ico" +)] +// When compiled for the rustc compiler itself we want to make sure that this is +// an unstable crate +#![cfg_attr(rustbuild, feature(staged_api, rustc_private))] +#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))] +#![deny(missing_debug_implementations, missing_docs)] + +use std::{borrow::Cow, cell::RefCell, env, io}; + +use log::{LevelFilter, Log, Metadata, Record, SetLoggerError}; + +pub mod filter; +pub mod fmt; + +pub use self::fmt::glob::*; + +use self::filter::Filter; +use self::fmt::writer::{self, Writer}; +use self::fmt::{FormatFn, Formatter}; + +/// The default name for the environment variable to read filters from. +pub const DEFAULT_FILTER_ENV: &str = "RUST_LOG"; + +/// The default name for the environment variable to read style preferences from. +pub const DEFAULT_WRITE_STYLE_ENV: &str = "RUST_LOG_STYLE"; + +/// Set of environment variables to configure from. +/// +/// # Default environment variables +/// +/// By default, the `Env` will read the following environment variables: +/// +/// - `RUST_LOG`: the level filter +/// - `RUST_LOG_STYLE`: whether or not to print styles with records. +/// +/// These sources can be configured using the builder methods on `Env`. +#[derive(Debug)] +pub struct Env<'a> { + filter: Var<'a>, + write_style: Var<'a>, +} + +#[derive(Debug)] +struct Var<'a> { + name: Cow<'a, str>, + default: Option<Cow<'a, str>>, +} + +/// The env logger. +/// +/// This struct implements the `Log` trait from the [`log` crate][log-crate-url], +/// which allows it to act as a logger. +/// +/// The [`init()`], [`try_init()`], [`Builder::init()`] and [`Builder::try_init()`] +/// methods will each construct a `Logger` and immediately initialize it as the +/// default global logger. +/// +/// If you'd instead need access to the constructed `Logger`, you can use +/// the associated [`Builder`] and install it with the +/// [`log` crate][log-crate-url] directly. +/// +/// [log-crate-url]: https://docs.rs/log/ +/// [`init()`]: fn.init.html +/// [`try_init()`]: fn.try_init.html +/// [`Builder::init()`]: struct.Builder.html#method.init +/// [`Builder::try_init()`]: struct.Builder.html#method.try_init +/// [`Builder`]: struct.Builder.html +pub struct Logger { + writer: Writer, + filter: Filter, + format: FormatFn, +} + +/// `Builder` acts as builder for initializing a `Logger`. +/// +/// It can be used to customize the log format, change the environment variable used +/// to provide the logging directives and also set the default log level filter. +/// +/// # Examples +/// +/// ``` +/// # #[macro_use] extern crate log; +/// # use std::io::Write; +/// use env_logger::Builder; +/// use log::LevelFilter; +/// +/// let mut builder = Builder::from_default_env(); +/// +/// builder +/// .format(|buf, record| writeln!(buf, "{} - {}", record.level(), record.args())) +/// .filter(None, LevelFilter::Info) +/// .init(); +/// +/// error!("error message"); +/// info!("info message"); +/// ``` +#[derive(Default)] +pub struct Builder { + filter: filter::Builder, + writer: writer::Builder, + format: fmt::Builder, + built: bool, +} + +impl Builder { + /// Initializes the log builder with defaults. + /// + /// **NOTE:** This method won't read from any environment variables. + /// Use the [`filter`] and [`write_style`] methods to configure the builder + /// or use [`from_env`] or [`from_default_env`] instead. + /// + /// # Examples + /// + /// Create a new builder and configure filters and style: + /// + /// ``` + /// use log::LevelFilter; + /// use env_logger::{Builder, WriteStyle}; + /// + /// let mut builder = Builder::new(); + /// + /// builder + /// .filter(None, LevelFilter::Info) + /// .write_style(WriteStyle::Always) + /// .init(); + /// ``` + /// + /// [`filter`]: #method.filter + /// [`write_style`]: #method.write_style + /// [`from_env`]: #method.from_env + /// [`from_default_env`]: #method.from_default_env + pub fn new() -> Builder { + Default::default() + } + + /// Initializes the log builder from the environment. + /// + /// The variables used to read configuration from can be tweaked before + /// passing in. + /// + /// # Examples + /// + /// Initialise a logger reading the log filter from an environment variable + /// called `MY_LOG`: + /// + /// ``` + /// use env_logger::Builder; + /// + /// let mut builder = Builder::from_env("MY_LOG"); + /// builder.init(); + /// ``` + /// + /// Initialise a logger using the `MY_LOG` variable for filtering and + /// `MY_LOG_STYLE` for whether or not to write styles: + /// + /// ``` + /// use env_logger::{Builder, Env}; + /// + /// let env = Env::new().filter("MY_LOG").write_style("MY_LOG_STYLE"); + /// + /// let mut builder = Builder::from_env(env); + /// builder.init(); + /// ``` + pub fn from_env<'a, E>(env: E) -> Self + where + E: Into<Env<'a>>, + { + let mut builder = Builder::new(); + builder.parse_env(env); + builder + } + + /// Applies the configuration from the environment. + /// + /// This function allows a builder to be configured with default parameters, + /// to be then overridden by the environment. + /// + /// # Examples + /// + /// Initialise a logger with filter level `Off`, then override the log + /// filter from an environment variable called `MY_LOG`: + /// + /// ``` + /// use log::LevelFilter; + /// use env_logger::Builder; + /// + /// let mut builder = Builder::new(); + /// + /// builder.filter_level(LevelFilter::Off); + /// builder.parse_env("MY_LOG"); + /// builder.init(); + /// ``` + /// + /// Initialise a logger with filter level `Off`, then use the `MY_LOG` + /// variable to override filtering and `MY_LOG_STYLE` to override whether + /// or not to write styles: + /// + /// ``` + /// use log::LevelFilter; + /// use env_logger::{Builder, Env}; + /// + /// let env = Env::new().filter("MY_LOG").write_style("MY_LOG_STYLE"); + /// + /// let mut builder = Builder::new(); + /// builder.filter_level(LevelFilter::Off); + /// builder.parse_env(env); + /// builder.init(); + /// ``` + pub fn parse_env<'a, E>(&mut self, env: E) -> &mut Self + where + E: Into<Env<'a>>, + { + let env = env.into(); + + if let Some(s) = env.get_filter() { + self.parse_filters(&s); + } + + if let Some(s) = env.get_write_style() { + self.parse_write_style(&s); + } + + self + } + + /// Initializes the log builder from the environment using default variable names. + /// + /// This method is a convenient way to call `from_env(Env::default())` without + /// having to use the `Env` type explicitly. The builder will use the + /// [default environment variables]. + /// + /// # Examples + /// + /// Initialise a logger using the default environment variables: + /// + /// ``` + /// use env_logger::Builder; + /// + /// let mut builder = Builder::from_default_env(); + /// builder.init(); + /// ``` + /// + /// [default environment variables]: struct.Env.html#default-environment-variables + pub fn from_default_env() -> Self { + Self::from_env(Env::default()) + } + + /// Applies the configuration from the environment using default variable names. + /// + /// This method is a convenient way to call `parse_env(Env::default())` without + /// having to use the `Env` type explicitly. The builder will use the + /// [default environment variables]. + /// + /// # Examples + /// + /// Initialise a logger with filter level `Off`, then configure it using the + /// default environment variables: + /// + /// ``` + /// use log::LevelFilter; + /// use env_logger::Builder; + /// + /// let mut builder = Builder::new(); + /// builder.filter_level(LevelFilter::Off); + /// builder.parse_default_env(); + /// builder.init(); + /// ``` + /// + /// [default environment variables]: struct.Env.html#default-environment-variables + pub fn parse_default_env(&mut self) -> &mut Self { + self.parse_env(Env::default()) + } + + /// Sets the format function for formatting the log output. + /// + /// This function is called on each record logged and should format the + /// log record and output it to the given [`Formatter`]. + /// + /// The format function is expected to output the string directly to the + /// `Formatter` so that implementations can use the [`std::fmt`] macros + /// to format and output without intermediate heap allocations. The default + /// `env_logger` formatter takes advantage of this. + /// + /// # Examples + /// + /// Use a custom format to write only the log message: + /// + /// ``` + /// use std::io::Write; + /// use env_logger::Builder; + /// + /// let mut builder = Builder::new(); + /// + /// builder.format(|buf, record| writeln!(buf, "{}", record.args())); + /// ``` + /// + /// [`Formatter`]: fmt/struct.Formatter.html + /// [`String`]: https://doc.rust-lang.org/stable/std/string/struct.String.html + /// [`std::fmt`]: https://doc.rust-lang.org/std/fmt/index.html + pub fn format<F: 'static>(&mut self, format: F) -> &mut Self + where + F: Fn(&mut Formatter, &Record) -> io::Result<()> + Sync + Send, + { + self.format.custom_format = Some(Box::new(format)); + self + } + + /// Use the default format. + /// + /// This method will clear any custom format set on the builder. + pub fn default_format(&mut self) -> &mut Self { + self.format = Default::default(); + self + } + + /// Whether or not to write the level in the default format. + pub fn format_level(&mut self, write: bool) -> &mut Self { + self.format.format_level = write; + self + } + + /// Whether or not to write the module path in the default format. + pub fn format_module_path(&mut self, write: bool) -> &mut Self { + self.format.format_module_path = write; + self + } + + /// Whether or not to write the target in the default format. + pub fn format_target(&mut self, write: bool) -> &mut Self { + self.format.format_target = write; + self + } + + /// Configures the amount of spaces to use to indent multiline log records. + /// A value of `None` disables any kind of indentation. + pub fn format_indent(&mut self, indent: Option<usize>) -> &mut Self { + self.format.format_indent = indent; + self + } + + /// Configures if timestamp should be included and in what precision. + pub fn format_timestamp(&mut self, timestamp: Option<fmt::TimestampPrecision>) -> &mut Self { + self.format.format_timestamp = timestamp; + self + } + + /// Configures the timestamp to use second precision. + pub fn format_timestamp_secs(&mut self) -> &mut Self { + self.format_timestamp(Some(fmt::TimestampPrecision::Seconds)) + } + + /// Configures the timestamp to use millisecond precision. + pub fn format_timestamp_millis(&mut self) -> &mut Self { + self.format_timestamp(Some(fmt::TimestampPrecision::Millis)) + } + + /// Configures the timestamp to use microsecond precision. + pub fn format_timestamp_micros(&mut self) -> &mut Self { + self.format_timestamp(Some(fmt::TimestampPrecision::Micros)) + } + + /// Configures the timestamp to use nanosecond precision. + pub fn format_timestamp_nanos(&mut self) -> &mut Self { + self.format_timestamp(Some(fmt::TimestampPrecision::Nanos)) + } + + /// Configures the end of line suffix. + pub fn format_suffix(&mut self, suffix: &'static str) -> &mut Self { + self.format.format_suffix = suffix; + self + } + + /// Adds a directive to the filter for a specific module. + /// + /// # Examples + /// + /// Only include messages for info and above for logs in `path::to::module`: + /// + /// ``` + /// use env_logger::Builder; + /// use log::LevelFilter; + /// + /// let mut builder = Builder::new(); + /// + /// builder.filter_module("path::to::module", LevelFilter::Info); + /// ``` + pub fn filter_module(&mut self, module: &str, level: LevelFilter) -> &mut Self { + self.filter.filter_module(module, level); + self + } + + /// Adds a directive to the filter for all modules. + /// + /// # Examples + /// + /// Only include messages for info and above for logs globally: + /// + /// ``` + /// use env_logger::Builder; + /// use log::LevelFilter; + /// + /// let mut builder = Builder::new(); + /// + /// builder.filter_level(LevelFilter::Info); + /// ``` + pub fn filter_level(&mut self, level: LevelFilter) -> &mut Self { + self.filter.filter_level(level); + self + } + + /// Adds filters to the logger. + /// + /// The given module (if any) will log at most the specified level provided. + /// If no module is provided then the filter will apply to all log messages. + /// + /// # Examples + /// + /// Only include messages for info and above for logs in `path::to::module`: + /// + /// ``` + /// use env_logger::Builder; + /// use log::LevelFilter; + /// + /// let mut builder = Builder::new(); + /// + /// builder.filter(Some("path::to::module"), LevelFilter::Info); + /// ``` + pub fn filter(&mut self, module: Option<&str>, level: LevelFilter) -> &mut Self { + self.filter.filter(module, level); + self + } + + /// Parses the directives string in the same form as the `RUST_LOG` + /// environment variable. + /// + /// See the module documentation for more details. + pub fn parse_filters(&mut self, filters: &str) -> &mut Self { + self.filter.parse(filters); + self + } + + /// Sets the target for the log output. + /// + /// Env logger can log to either stdout, stderr or a custom pipe. The default is stderr. + /// + /// The custom pipe can be used to send the log messages to a custom sink (for example a file). + /// Do note that direct writes to a file can become a bottleneck due to IO operation times. + /// + /// # Examples + /// + /// Write log message to `stdout`: + /// + /// ``` + /// use env_logger::{Builder, Target}; + /// + /// let mut builder = Builder::new(); + /// + /// builder.target(Target::Stdout); + /// ``` + pub fn target(&mut self, target: fmt::Target) -> &mut Self { + self.writer.target(target); + self + } + + /// Sets whether or not styles will be written. + /// + /// This can be useful in environments that don't support control characters + /// for setting colors. + /// + /// # Examples + /// + /// Never attempt to write styles: + /// + /// ``` + /// use env_logger::{Builder, WriteStyle}; + /// + /// let mut builder = Builder::new(); + /// + /// builder.write_style(WriteStyle::Never); + /// ``` + pub fn write_style(&mut self, write_style: fmt::WriteStyle) -> &mut Self { + self.writer.write_style(write_style); + self + } + + /// Parses whether or not to write styles in the same form as the `RUST_LOG_STYLE` + /// environment variable. + /// + /// See the module documentation for more details. + pub fn parse_write_style(&mut self, write_style: &str) -> &mut Self { + self.writer.parse_write_style(write_style); + self + } + + /// Sets whether or not the logger will be used in unit tests. + /// + /// If `is_test` is `true` then the logger will allow the testing framework to + /// capture log records rather than printing them to the terminal directly. + pub fn is_test(&mut self, is_test: bool) -> &mut Self { + self.writer.is_test(is_test); + self + } + + /// Initializes the global logger with the built env logger. + /// + /// This should be called early in the execution of a Rust program. Any log + /// events that occur before initialization will be ignored. + /// + /// # Errors + /// + /// This function will fail if it is called more than once, or if another + /// library has already initialized a global logger. + pub fn try_init(&mut self) -> Result<(), SetLoggerError> { + let logger = self.build(); + + let max_level = logger.filter(); + let r = log::set_boxed_logger(Box::new(logger)); + + if r.is_ok() { + log::set_max_level(max_level); + } + + r + } + + /// Initializes the global logger with the built env logger. + /// + /// This should be called early in the execution of a Rust program. Any log + /// events that occur before initialization will be ignored. + /// + /// # Panics + /// + /// This function will panic if it is called more than once, or if another + /// library has already initialized a global logger. + pub fn init(&mut self) { + self.try_init() + .expect("Builder::init should not be called after logger initialized"); + } + + /// Build an env logger. + /// + /// The returned logger implements the `Log` trait and can be installed manually + /// or nested within another logger. + pub fn build(&mut self) -> Logger { + assert!(!self.built, "attempt to re-use consumed builder"); + self.built = true; + + Logger { + writer: self.writer.build(), + filter: self.filter.build(), + format: self.format.build(), + } + } +} + +impl Logger { + /// Creates the logger from the environment. + /// + /// The variables used to read configuration from can be tweaked before + /// passing in. + /// + /// # Examples + /// + /// Create a logger reading the log filter from an environment variable + /// called `MY_LOG`: + /// + /// ``` + /// use env_logger::Logger; + /// + /// let logger = Logger::from_env("MY_LOG"); + /// ``` + /// + /// Create a logger using the `MY_LOG` variable for filtering and + /// `MY_LOG_STYLE` for whether or not to write styles: + /// + /// ``` + /// use env_logger::{Logger, Env}; + /// + /// let env = Env::new().filter_or("MY_LOG", "info").write_style_or("MY_LOG_STYLE", "always"); + /// + /// let logger = Logger::from_env(env); + /// ``` + pub fn from_env<'a, E>(env: E) -> Self + where + E: Into<Env<'a>>, + { + Builder::from_env(env).build() + } + + /// Creates the logger from the environment using default variable names. + /// + /// This method is a convenient way to call `from_env(Env::default())` without + /// having to use the `Env` type explicitly. The logger will use the + /// [default environment variables]. + /// + /// # Examples + /// + /// Creates a logger using the default environment variables: + /// + /// ``` + /// use env_logger::Logger; + /// + /// let logger = Logger::from_default_env(); + /// ``` + /// + /// [default environment variables]: struct.Env.html#default-environment-variables + pub fn from_default_env() -> Self { + Builder::from_default_env().build() + } + + /// Returns the maximum `LevelFilter` that this env logger instance is + /// configured to output. + pub fn filter(&self) -> LevelFilter { + self.filter.filter() + } + + /// Checks if this record matches the configured filter. + pub fn matches(&self, record: &Record) -> bool { + self.filter.matches(record) + } +} + +impl Log for Logger { + fn enabled(&self, metadata: &Metadata) -> bool { + self.filter.enabled(metadata) + } + + fn log(&self, record: &Record) { + if self.matches(record) { + // Log records are written to a thread-local buffer before being printed + // to the terminal. We clear these buffers afterwards, but they aren't shrunk + // so will always at least have capacity for the largest log record formatted + // on that thread. + // + // If multiple `Logger`s are used by the same threads then the thread-local + // formatter might have different color support. If this is the case the + // formatter and its buffer are discarded and recreated. + + thread_local! { + static FORMATTER: RefCell<Option<Formatter>> = RefCell::new(None); + } + + let print = |formatter: &mut Formatter, record: &Record| { + let _ = + (self.format)(formatter, record).and_then(|_| formatter.print(&self.writer)); + + // Always clear the buffer afterwards + formatter.clear(); + }; + + let printed = FORMATTER + .try_with(|tl_buf| { + match tl_buf.try_borrow_mut() { + // There are no active borrows of the buffer + Ok(mut tl_buf) => match *tl_buf { + // We have a previously set formatter + Some(ref mut formatter) => { + // Check the buffer style. If it's different from the logger's + // style then drop the buffer and recreate it. + if formatter.write_style() != self.writer.write_style() { + *formatter = Formatter::new(&self.writer); + } + + print(formatter, record); + } + // We don't have a previously set formatter + None => { + let mut formatter = Formatter::new(&self.writer); + print(&mut formatter, record); + + *tl_buf = Some(formatter); + } + }, + // There's already an active borrow of the buffer (due to re-entrancy) + Err(_) => { + print(&mut Formatter::new(&self.writer), record); + } + } + }) + .is_ok(); + + if !printed { + // The thread-local storage was not available (because its + // destructor has already run). Create a new single-use + // Formatter on the stack for this call. + print(&mut Formatter::new(&self.writer), record); + } + } + } + + fn flush(&self) {} +} + +impl<'a> Env<'a> { + /// Get a default set of environment variables. + pub fn new() -> Self { + Self::default() + } + + /// Specify an environment variable to read the filter from. + pub fn filter<E>(mut self, filter_env: E) -> Self + where + E: Into<Cow<'a, str>>, + { + self.filter = Var::new(filter_env); + + self + } + + /// Specify an environment variable to read the filter from. + /// + /// If the variable is not set, the default value will be used. + pub fn filter_or<E, V>(mut self, filter_env: E, default: V) -> Self + where + E: Into<Cow<'a, str>>, + V: Into<Cow<'a, str>>, + { + self.filter = Var::new_with_default(filter_env, default); + + self + } + + /// Use the default environment variable to read the filter from. + /// + /// If the variable is not set, the default value will be used. + pub fn default_filter_or<V>(mut self, default: V) -> Self + where + V: Into<Cow<'a, str>>, + { + self.filter = Var::new_with_default(DEFAULT_FILTER_ENV, default); + + self + } + + fn get_filter(&self) -> Option<String> { + self.filter.get() + } + + /// Specify an environment variable to read the style from. + pub fn write_style<E>(mut self, write_style_env: E) -> Self + where + E: Into<Cow<'a, str>>, + { + self.write_style = Var::new(write_style_env); + + self + } + + /// Specify an environment variable to read the style from. + /// + /// If the variable is not set, the default value will be used. + pub fn write_style_or<E, V>(mut self, write_style_env: E, default: V) -> Self + where + E: Into<Cow<'a, str>>, + V: Into<Cow<'a, str>>, + { + self.write_style = Var::new_with_default(write_style_env, default); + + self + } + + /// Use the default environment variable to read the style from. + /// + /// If the variable is not set, the default value will be used. + pub fn default_write_style_or<V>(mut self, default: V) -> Self + where + V: Into<Cow<'a, str>>, + { + self.write_style = Var::new_with_default(DEFAULT_WRITE_STYLE_ENV, default); + + self + } + + fn get_write_style(&self) -> Option<String> { + self.write_style.get() + } +} + +impl<'a> Var<'a> { + fn new<E>(name: E) -> Self + where + E: Into<Cow<'a, str>>, + { + Var { + name: name.into(), + default: None, + } + } + + fn new_with_default<E, V>(name: E, default: V) -> Self + where + E: Into<Cow<'a, str>>, + V: Into<Cow<'a, str>>, + { + Var { + name: name.into(), + default: Some(default.into()), + } + } + + fn get(&self) -> Option<String> { + env::var(&*self.name) + .ok() + .or_else(|| self.default.to_owned().map(|v| v.into_owned())) + } +} + +impl<'a, T> From<T> for Env<'a> +where + T: Into<Cow<'a, str>>, +{ + fn from(filter_env: T) -> Self { + Env::default().filter(filter_env.into()) + } +} + +impl<'a> Default for Env<'a> { + fn default() -> Self { + Env { + filter: Var::new(DEFAULT_FILTER_ENV), + write_style: Var::new(DEFAULT_WRITE_STYLE_ENV), + } + } +} + +mod std_fmt_impls { + use super::*; + use std::fmt; + + impl fmt::Debug for Logger { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_struct("Logger") + .field("filter", &self.filter) + .finish() + } + } + + impl fmt::Debug for Builder { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + if self.built { + f.debug_struct("Logger").field("built", &true).finish() + } else { + f.debug_struct("Logger") + .field("filter", &self.filter) + .field("writer", &self.writer) + .finish() + } + } + } +} + +/// Attempts to initialize the global logger with an env logger. +/// +/// This should be called early in the execution of a Rust program. Any log +/// events that occur before initialization will be ignored. +/// +/// # Errors +/// +/// This function will fail if it is called more than once, or if another +/// library has already initialized a global logger. +pub fn try_init() -> Result<(), SetLoggerError> { + try_init_from_env(Env::default()) +} + +/// Initializes the global logger with an env logger. +/// +/// This should be called early in the execution of a Rust program. Any log +/// events that occur before initialization will be ignored. +/// +/// # Panics +/// +/// This function will panic if it is called more than once, or if another +/// library has already initialized a global logger. +pub fn init() { + try_init().expect("env_logger::init should not be called after logger initialized"); +} + +/// Attempts to initialize the global logger with an env logger from the given +/// environment variables. +/// +/// This should be called early in the execution of a Rust program. Any log +/// events that occur before initialization will be ignored. +/// +/// # Examples +/// +/// Initialise a logger using the `MY_LOG` environment variable for filters +/// and `MY_LOG_STYLE` for writing colors: +/// +/// ``` +/// use env_logger::{Builder, Env}; +/// +/// # fn run() -> Result<(), Box<dyn ::std::error::Error>> { +/// let env = Env::new().filter("MY_LOG").write_style("MY_LOG_STYLE"); +/// +/// env_logger::try_init_from_env(env)?; +/// +/// Ok(()) +/// # } +/// # run().unwrap(); +/// ``` +/// +/// # Errors +/// +/// This function will fail if it is called more than once, or if another +/// library has already initialized a global logger. +pub fn try_init_from_env<'a, E>(env: E) -> Result<(), SetLoggerError> +where + E: Into<Env<'a>>, +{ + let mut builder = Builder::from_env(env); + + builder.try_init() +} + +/// Initializes the global logger with an env logger from the given environment +/// variables. +/// +/// This should be called early in the execution of a Rust program. Any log +/// events that occur before initialization will be ignored. +/// +/// # Examples +/// +/// Initialise a logger using the `MY_LOG` environment variable for filters +/// and `MY_LOG_STYLE` for writing colors: +/// +/// ``` +/// use env_logger::{Builder, Env}; +/// +/// let env = Env::new().filter("MY_LOG").write_style("MY_LOG_STYLE"); +/// +/// env_logger::init_from_env(env); +/// ``` +/// +/// # Panics +/// +/// This function will panic if it is called more than once, or if another +/// library has already initialized a global logger. +pub fn init_from_env<'a, E>(env: E) +where + E: Into<Env<'a>>, +{ + try_init_from_env(env) + .expect("env_logger::init_from_env should not be called after logger initialized"); +} + +/// Create a new builder with the default environment variables. +/// +/// The builder can be configured before being initialized. +/// This is a convenient way of calling [`Builder::from_default_env`]. +/// +/// [`Builder::from_default_env`]: struct.Builder.html#method.from_default_env +pub fn builder() -> Builder { + Builder::from_default_env() +} + +/// Create a builder from the given environment variables. +/// +/// The builder can be configured before being initialized. +#[deprecated( + since = "0.8.0", + note = "Prefer `env_logger::Builder::from_env()` instead." +)] +pub fn from_env<'a, E>(env: E) -> Builder +where + E: Into<Env<'a>>, +{ + Builder::from_env(env) +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn env_get_filter_reads_from_var_if_set() { + env::set_var("env_get_filter_reads_from_var_if_set", "from var"); + + let env = Env::new().filter_or("env_get_filter_reads_from_var_if_set", "from default"); + + assert_eq!(Some("from var".to_owned()), env.get_filter()); + } + + #[test] + fn env_get_filter_reads_from_default_if_var_not_set() { + env::remove_var("env_get_filter_reads_from_default_if_var_not_set"); + + let env = Env::new().filter_or( + "env_get_filter_reads_from_default_if_var_not_set", + "from default", + ); + + assert_eq!(Some("from default".to_owned()), env.get_filter()); + } + + #[test] + fn env_get_write_style_reads_from_var_if_set() { + env::set_var("env_get_write_style_reads_from_var_if_set", "from var"); + + let env = + Env::new().write_style_or("env_get_write_style_reads_from_var_if_set", "from default"); + + assert_eq!(Some("from var".to_owned()), env.get_write_style()); + } + + #[test] + fn env_get_write_style_reads_from_default_if_var_not_set() { + env::remove_var("env_get_write_style_reads_from_default_if_var_not_set"); + + let env = Env::new().write_style_or( + "env_get_write_style_reads_from_default_if_var_not_set", + "from default", + ); + + assert_eq!(Some("from default".to_owned()), env.get_write_style()); + } + + #[test] + fn builder_parse_env_overrides_existing_filters() { + env::set_var( + "builder_parse_default_env_overrides_existing_filters", + "debug", + ); + let env = Env::new().filter("builder_parse_default_env_overrides_existing_filters"); + + let mut builder = Builder::new(); + builder.filter_level(LevelFilter::Trace); + // Overrides global level to debug + builder.parse_env(env); + + assert_eq!(builder.filter.build().filter(), LevelFilter::Debug); + } +} |