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47 lines
1.5 KiB
Rust

//! Custom log formatter that includes source file and line for WARN/ERROR events.
use std::fmt;
use tracing::{Event, Level, Subscriber};
use tracing_subscriber::fmt::format::{self, FormatEvent, FormatFields};
use tracing_subscriber::fmt::FmtContext;
use tracing_subscriber::registry::LookupSpan;
/// Event formatter that appends `[file:line]` to WARN and ERROR log lines.
///
/// INFO, DEBUG, and TRACE events use the default format without source location.
pub struct ErrorLocationFormat;
impl<S, N> FormatEvent<S, N> for ErrorLocationFormat
where
S: Subscriber + for<'a> LookupSpan<'a>,
N: for<'a> FormatFields<'a> + 'static,
{
fn format_event(
&self,
ctx: &FmtContext<'_, S, N>,
mut writer: format::Writer<'_>,
event: &Event<'_>,
) -> fmt::Result {
let metadata = event.metadata();
let level = metadata.level();
let timestamp = chrono::Utc::now().format("%Y-%m-%dT%H:%M:%S%.6fZ");
// Write: timestamp + level + target
write!(writer, "{} {:>5} {}", timestamp, level, metadata.target())?;
// Append [file:line] for WARN and ERROR only
if *level <= Level::WARN {
if let (Some(file), Some(line)) = (metadata.file(), metadata.line()) {
write!(writer, " [{}:{}]", file, line)?;
}
}
write!(writer, ": ")?;
// Write the event fields (message, structured fields)
ctx.format_fields(writer.by_ref(), event)?;
writeln!(writer)
}
}