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//! The logosaurus crate provides a logging implementation that works with the [`log`] crate. The //! crate and the logger are modeled after the Go standard library's log package. //! //! The primary type is [`Logger`], which represents a logging object. Use //! [`init`] to globally initialize a logger with the `log` crate. //! //! Every log message is output on a separate line: if the message being printed does not end in a //! newline, the logger will add one. //! //! The default logger writes logs to stderr using this format: //! ```txt //! WARN 2020/10/02 21:27:03 hello, world //! ``` //! //! # Examples //! //! ## Using the default logger //! //! ``` //! use log::{debug}; //! use logosaurus::{Logger}; //! //! fn main() { //! logosaurus::init(Logger::default()).unwrap(); //! debug!("hello, world"); // DEBUG 2020/10/02 21:27:03 hello, world //! } //! ``` //! //! ## Using a custom logger //! //! ``` //! use log::{self, debug}; //! use logosaurus::{Logger, L_STD, L_SHORT_FILE, L_MICROSECONDS}; //! use std::io; //! //! fn main() { //! let logger = Logger::builder(io::stdout()) //! .set_level(log::LevelFilter::Debug) //! .set_flags(L_STD | L_SHORT_FILE | L_MICROSECONDS) //! .set_prefix("myprogram: ") //! .build(); //! //! logosaurus::init(logger).unwrap(); //! debug!("hello, world"); // myprogram: DEBUG 2020/10/02 21:27:03.123123 main.rs:12: hello, world //! } //! ``` //! //! [`log`]: https://crates.io/crates/log //! [`Logger`]: struct.Logger.html //! [`init`]: fn.init.html use chrono::{self, Timelike}; use log; use std::fmt; use std::io::{self, Write}; use std::path; use std::sync::Mutex; /// Formatting flags for the header in log output. /// See the `L_*` constants. /// /// With the exception of the `L_MSG_PREFIX` flag, there is no control over the order that header /// text appears, or the format they present (described in the `L*` constants). /// /// For example, the `L_DATE | L_TIME` flags produce: /// ```txt /// 2009/01/23 17:05:23 message /// ``` /// while `L_DATE | L_TIME | L_MICROSECONDS | L_SHORT_FILE | L_LEVEL` produce: /// ```txt /// INFO 2009/01/23 17:05:23.123123 main.rs:3: message /// ``` pub type Flag = u8; /// No header. pub const L_NONE: Flag = 0; /// Date in local time zone: 2009/01/23. pub const L_DATE: Flag = 1; /// Time in local time zone: 17:05:23. pub const L_TIME: Flag = 2; /// Microsecond resolution: 17:05:23.023123; assumes `L_TIME`. pub const L_MICROSECONDS: Flag = 4; /// Module, file name, and line number: `foo src/file.rs:3`. pub const L_LONG_FILE: Flag = 8; /// Final file name element and line number: `file.rs:3`. pub const L_SHORT_FILE: Flag = 16; /// If `L_DATE` or `L_TIME` is set, use UTC rather than the local time. pub const L_UTC: Flag = 32; /// Move the "prefix" from the beginning of the header to the end of the header, just before the /// message. pub const L_MSG_PREFIX: Flag = 64; /// Log level printed in capitalized form: INFO, TRACE, etc. Padded to width 5. pub const L_LEVEL: Flag = 128; /// Initial values for the default logger constructed with `Logger::default()`. pub const L_STD: Flag = L_DATE | L_TIME | L_LEVEL; // TODO: https://doc.rust-lang.org/beta/unstable-book/language-features/trait-alias.html // Rewrite as trait alias when stable. // trait W = Write + Send /// Builder for [`Logger`]. /// /// Use `Logger:builder()` to obtain a `LoggerBuilder`. /// /// Unmodified or unset values in the builder will default to the values used by /// [`Logger::default()`]. /// /// # Example /// /// ``` /// use log; /// use logosaurus::{Logger, L_STD, L_SHORT_FILE}; /// use std::io; /// /// let mut builder = Logger::builder(io::stdout()); /// let logger = builder /// .set_level(log::LevelFilter::Debug) /// .set_flags(L_STD | L_SHORT_FILE) /// .set_prefix("myprogram: ") /// .build(); /// ``` /// /// [`Logger`]: struct.Logger.html /// [`Logger::default()`]: struct.Logger.html#impl-Default pub struct LoggerBuilder<W: Write + Send> { level: log::LevelFilter, out: Option<W>, flag: Flag, prefix: String, } impl<W: Write + Send> LoggerBuilder<W> { /// Set the allowed log level. pub fn set_level(mut self, level: log::LevelFilter) -> LoggerBuilder<W> { self.level = level; self } /// Set the formatting flags. pub fn set_flags(mut self, flag: Flag) -> LoggerBuilder<W> { self.flag = flag; self } /// Set the prefix. pub fn set_prefix(mut self, prefix: &str) -> LoggerBuilder<W> { self.prefix = String::from(prefix); self } /// Construct a `Logger` from this `LoggerBuilder`. Consumes the /// `LoggerBuilder`. pub fn build(mut self) -> Logger<W> { Logger { level: self.level, out: Mutex::new(self.out.take().unwrap()), flag: self.flag, prefix: self.prefix.clone(), } } } /// Represents a logging object that writes to a specified output. It can be used simultaneously /// from multiple threads; it guarantees to serialize writes. /// /// Use [`LoggerBuilder`] to construct a `Logger`, or use `Logger::default()`. /// /// [`LoggerBuilder`]: struct.LoggerBuilder.html pub struct Logger<W: Write + Send> { level: log::LevelFilter, out: Mutex<W>, flag: Flag, prefix: String, } /// Initialize the logger to use with the [`log`] crate. /// /// ``` /// use log::{debug}; /// /// fn main() { /// logosaurus::init(logosaurus::Logger::default()).unwrap(); /// debug!("hello, world"); /// } /// ``` // /// See [`LoggerBuilder`] to create a custom logger. /// /// [`log`]: https://crates.io/crates/log /// [`LoggerBuilder`]: struct.LoggerBuilder.html pub fn init<W: Write + Send + 'static>(l: Logger<W>) -> Result<(), log::SetLoggerError> { log::set_max_level(l.level); log::set_boxed_logger(Box::new(l)) } impl<W: Write + Send> Logger<W> { /// Returns a `LoggerBuilder` that can be used to build a `Logger`. pub fn builder(w: W) -> LoggerBuilder<W> { LoggerBuilder { level: log::LevelFilter::Trace, out: Some(w), flag: L_STD, prefix: String::from(""), } } /// Writes the given string `s` using the logger. Typically, you would not use this directly /// but instead use the macros provided by the `log` crate. pub fn write_output( &self, level: log::Level, target: &str, file: Option<&str>, line: Option<u32>, s: &str, ) { if !self.enabled(level) { return; } let now = chrono::offset::Local::now(); // get this early let file = match file { Some(f) => f, None => "???", }; let line = match line { Some(n) => n, None => 0, }; let h = self.header(target, file, line, level, now); let maybe_newline = if s.ends_with("\n") { "" } else { "\n" }; let mut out = self.out.lock().unwrap(); let _ = write!(out, "{}{}{}", h, s, maybe_newline); } fn write_record(&self, record: &log::Record) { self.write_output( record.level(), record.target(), record.file(), record.line(), &record.args().to_string(), ); } fn header<Tz: chrono::TimeZone>( &self, target: &str, file: &str, line: u32, level: log::Level, now: chrono::DateTime<Tz>, ) -> String where Tz::Offset: fmt::Display, { header_with_flags(target, file, line, level, now, self.flag, &self.prefix) } fn enabled(&self, incoming_level: log::Level) -> bool { incoming_level <= self.level } } fn format_datetime<Tz: chrono::TimeZone>(buf: &mut String, flag: Flag, now: chrono::DateTime<Tz>) where Tz::Offset: fmt::Display, { if flag & L_DATE != 0 { buf.push_str(&format!("{} ", now.format("%Y/%m/%d"))); } if flag & (L_TIME | L_MICROSECONDS) != 0 { buf.push_str(&format!("{}", now.format("%H:%M:%S"))); if flag & L_MICROSECONDS != 0 { let micro = now.nanosecond() / 1000; buf.push_str(&format!(".{:0>wid$}", micro, wid = 6)); } buf.push_str(&format!(" ")); } } fn header_with_flags<Tz: chrono::TimeZone>( target: &str, file: &str, line: u32, level: log::Level, now: chrono::DateTime<Tz>, flag: Flag, prefix: &str, ) -> String where Tz::Offset: fmt::Display, { let mut buf = String::new(); if flag & L_MSG_PREFIX == 0 { buf.push_str(&format!("{}", prefix)); } if flag & L_LEVEL != 0 { buf.push_str(&format!("{: <5} ", level)); } if flag & (L_DATE | L_TIME | L_MICROSECONDS) != 0 { if flag & L_UTC != 0 { let now = now.with_timezone(&chrono::Utc); format_datetime(&mut buf, flag, now); } else { format_datetime(&mut buf, flag, now); } } if flag & (L_LONG_FILE | L_SHORT_FILE) != 0 { if flag & L_LONG_FILE != 0 { buf.push_str(&format!("{} ", target)); } // TODO: reduce String::from calls let f = if flag & L_SHORT_FILE != 0 { match path::Path::new(file).file_name() { Some(base) => base.to_string_lossy().into_owned(), None => String::from("???"), } } else { String::from(file) }; buf.push_str(&format!("{}", f)); buf.push_str(&format!(":{}", line)); buf.push_str(&format!(": ")); } if flag & L_MSG_PREFIX != 0 { buf.push_str(&format!("{}", prefix)); } buf } impl Default for Logger<io::Stderr> { /// Returns a default `Logger`. /// /// A default `Logger` has /// * level: `log::LevelFilter::Trace`, /// * out: stderr, /// * flags: `L_STD`, and /// * prefix: `""` (empty string) /// fn default() -> Logger<io::Stderr> { Logger::builder(io::stderr()).build() } } impl<W: Write + Send> log::Log for Logger<W> { fn enabled(&self, metadata: &log::Metadata) -> bool { self.enabled(metadata.level()) } fn log(&self, record: &log::Record) { self.write_record(record); } fn flush(&self) { let _ = self.out.lock().unwrap().flush(); } } #[doc(hidden)] pub mod test_util; #[cfg(test)] mod tests { use super::*; use chrono::prelude::*; #[test] fn test_header() { let time = FixedOffset::east(3600 * 5 + 1800) .ymd(2020, 10, 3) .and_hms_micro(1, 2, 3, 9876); let flags = L_STD | L_MICROSECONDS | L_SHORT_FILE; let expect = "TRACE 2020/10/03 01:02:03.009876 file.rs:9: "; let got = header_with_flags( "foo", "src/dir/file.rs", 9, log::Level::Trace, time, flags, "", ); assert_eq!(expect, got); let flags = L_DATE | L_TIME | L_UTC | L_LONG_FILE; let expect = "2020/10/02 19:32:03 foo src/dir/file.rs:9: "; let got = header_with_flags( "foo", "src/dir/file.rs", 9, log::Level::Info, time, flags, "", ); assert_eq!(expect, got); let flags = L_TIME | L_LEVEL; let prefix = "myprog: "; let expect = "myprog: INFO 01:02:03 "; let got = header_with_flags( "foo", "src/dir/file.rs", 9, log::Level::Info, time, flags, prefix, ); assert_eq!(expect, got); let flags = L_MSG_PREFIX | L_TIME | L_LEVEL; let expect = "INFO 01:02:03 myprog: "; let got = header_with_flags( "foo", "src/dir/file.rs", 9, log::Level::Info, time, flags, prefix, ); assert_eq!(expect, got); } }