log: add timestamp to stdout_logger

UTC timestamp to `stdout_logger`.
Show on default, parameter available.

Author: arkjedrz

Cargo.lock

@@ -24,6 +24,7 @@ rust_library(
     visibility = ["//visibility:public"],
     deps = [
         "//src/log/score_log",
+        "@score_crates//:time",
     ],
 )
 

src/log/stdout_logger/BUILD

@@ -10,6 +10,7 @@ path = "lib.rs"
 
 [dependencies]
 score_log.workspace = true
+time = { version = "0.3.44", features = ["macros", "formatting"] }
 
 [lints]
 workspace = true

src/log/stdout_logger/Cargo.toml

@@ -18,6 +18,13 @@ use core::cell::RefCell;
 use core::fmt::Write;
 use score_log::fmt::{score_write, Error, FormatSpec, Result, ScoreWrite};
 use score_log::{LevelFilter, Log, Metadata, Record};
+use time::format_description::FormatItem;
+use time::macros::format_description;
+use time::UtcDateTime;
+
+/// Timestamp format matches the `score::mw::log` format.
+const TIMESTAMP_FORMAT: &[FormatItem<'_>] =
+    format_description!("[year]/[month]/[day] [hour]:[minute]:[second].[subsecond digits:7]");
 
 /// Fixed size buffer for strings.
 struct FixedBuf<const N: usize> {
@@ -191,6 +198,15 @@ impl StdoutLoggerBuilder {
         self
     }
 
+    /// Show timestamp.
+    ///
+    /// UTC timestamp in following format:
+    /// "[year]/[month]/[day] [hour]:[minute]:[second].[subsecond digits:7]"
+    pub fn show_timestamp(mut self, show_timestamp: bool) -> Self {
+        self.0.show_timestamp = show_timestamp;
+        self
+    }
+
     /// Filter logs by level.
     pub fn log_level(mut self, log_level: LevelFilter) -> Self {
         self.0.log_level = log_level;
@@ -226,6 +242,7 @@ impl Default for StdoutLoggerBuilder {
             show_module: false,
             show_file: false,
             show_line: false,
+            show_timestamp: true,
             log_level: LevelFilter::Info,
         })
     }
@@ -241,6 +258,7 @@ pub struct StdoutLogger {
     show_module: bool,
     show_file: bool,
     show_line: bool,
+    show_timestamp: bool,
     log_level: LevelFilter,
 }
 
@@ -269,6 +287,14 @@ impl Log for StdoutLogger {
 
         // Operate in a scope of borrowed writer.
         WRITER.with_borrow_mut(|writer| {
+            // Write timestamp.
+            if self.show_timestamp {
+                let timestamp = UtcDateTime::now()
+                    .format(&TIMESTAMP_FORMAT)
+                    .expect("failed to format timestamp");
+                let _ = score_write!(writer, "[{}]", timestamp);
+            }
+
             // Write module, file and line.
             if self.show_module || self.show_file || self.show_line {
                 let _ = score_write!(writer, "[");