eric
bc2ee2d374
Each scpcap invocation now starts its log fresh. Appending meant a re-run after a failed attempt mixed new output in with (or could be mistaken for) stale output from the previous run -- confusing when diagnosing exactly this kind of issue in production.
34 lines
1.2 KiB
Rust
34 lines
1.2 KiB
Rust
use std::fs::{File, OpenOptions};
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use std::io::Write;
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use std::path::Path;
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use std::sync::Mutex;
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use std::time::{SystemTime, UNIX_EPOCH};
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/// Optional diagnostic trace, one timestamped line per event, for diagnosing
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/// where a transfer stalls (e.g. which side is still waiting, and on what).
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/// `Logger::none()` is a no-op so call sites don't need to branch on whether
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/// `--log` was given.
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pub struct Logger(Option<Mutex<File>>);
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impl Logger {
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pub fn none() -> Logger {
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Logger(None)
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}
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/// Truncates any existing file at `path` -- each run starts a fresh
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/// log, so a re-run never leaves stale lines from a previous attempt
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/// mixed in with (or mistaken for) the current one.
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pub fn open(path: &Path) -> std::io::Result<Logger> {
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let f = OpenOptions::new().create(true).write(true).truncate(true).open(path)?;
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Ok(Logger(Some(Mutex::new(f))))
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}
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pub fn log(&self, args: std::fmt::Arguments) {
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let Some(m) = &self.0 else { return };
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let now = SystemTime::now().duration_since(UNIX_EPOCH).unwrap_or_default();
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if let Ok(mut f) = m.lock() {
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let _ = writeln!(f, "[{:.6}] {}", now.as_secs_f64(), args);
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}
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}
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}
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